From 76ed2199491397e0f9902ade80d5271e4a9b2630 Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Wed, 16 Oct 2019 06:05:39 +0000
Subject: upstream: potential NULL dereference for revoked hostkeys; reported

by krishnaiah bommu

OpenBSD-Commit-ID: 35ff685e7cc9dd2e3fe2e3dfcdcb9bc5c79f6506
---
 auth.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'auth.c')

diff --git a/auth.c b/auth.c
index ca450f4e4..b092f212c 100644
--- a/auth.c
+++ b/auth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.141 2019/10/02 00:42:30 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.142 2019/10/16 06:05:39 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -489,7 +489,7 @@ check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
 	host_status = check_key_in_hostkeys(hostkeys, key, &found);
 	if (host_status == HOST_REVOKED)
 		error("WARNING: revoked key for %s attempted authentication",
-		    found->host);
+		    host);
 	else if (host_status == HOST_OK)
 		debug("%s: key for %s found at %s:%ld", __func__,
 		    found->host, found->file, found->line);
-- 
cgit v1.2.3


From 2e71263b80fec7ad977e098004fef7d122169d40 Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Mon, 25 Nov 2019 00:54:23 +0000
Subject: upstream: add a "no-touch-required" option for authorized_keys and

a similar extension for certificates. This option disables the default
requirement that security key signatures attest that the user touched their
key to authorize them.

feedback deraadt, ok markus

OpenBSD-Commit-ID: f1fb56151ba68d55d554d0f6d3d4dba0cf1a452e
---
 auth-options.c | 38 ++++++++++++++++++++++++++------------
 auth-options.h |  5 ++++-
 auth.c         |  7 ++++---
 auth2-pubkey.c |  5 +++--
 monitor.c      |  5 +++--
 ssh-keygen.1   | 12 ++++++++++--
 ssh-keygen.c   | 25 +++++++++++++++++--------
 sshd.8         | 13 +++++++++++--
 8 files changed, 78 insertions(+), 32 deletions(-)

(limited to 'auth.c')

diff --git a/auth-options.c b/auth-options.c
index 90b0d7f25..2d200944c 100644
--- a/auth-options.c
+++ b/auth-options.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.c,v 1.89 2019/09/13 04:36:43 dtucker Exp $ */
+/* $OpenBSD: auth-options.c,v 1.90 2019/11/25 00:54:23 djm Exp $ */
 /*
  * Copyright (c) 2018 Damien Miller <djm@mindrot.org>
  *
@@ -96,7 +96,10 @@ cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob,
 		    name, sshbuf_len(data));
 		found = 0;
 		if ((which & OPTIONS_EXTENSIONS) != 0) {
-			if (strcmp(name, "permit-X11-forwarding") == 0) {
+			if (strcmp(name, "no-touch-required") == 0) {
+				opts->no_require_user_presence = 1;
+				found = 1;
+			} else if (strcmp(name, "permit-X11-forwarding") == 0) {
 				opts->permit_x11_forwarding_flag = 1;
 				found = 1;
 			} else if (strcmp(name,
@@ -347,6 +350,8 @@ sshauthopt_parse(const char *opts, const char **errstrp)
 			ret->permit_agent_forwarding_flag = r == 1;
 		} else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
 			ret->permit_x11_forwarding_flag = r == 1;
+		} else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
+			ret->no_require_user_presence = r != 1; /* NB. flip */
 		} else if ((r = opt_flag("pty", 1, &opts)) != -1) {
 			ret->permit_pty_flag = r == 1;
 		} else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
@@ -567,14 +572,15 @@ sshauthopt_merge(const struct sshauthopt *primary,
 			goto alloc_fail;
 	}
 
-	/* Flags are logical-AND (i.e. must be set in both for permission) */
-#define OPTFLAG(x) ret->x = (primary->x == 1) && (additional->x == 1)
-	OPTFLAG(permit_port_forwarding_flag);
-	OPTFLAG(permit_agent_forwarding_flag);
-	OPTFLAG(permit_x11_forwarding_flag);
-	OPTFLAG(permit_pty_flag);
-	OPTFLAG(permit_user_rc);
-#undef OPTFLAG
+#define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
+	/* Permissive flags are logical-AND (i.e. must be set in both) */
+	OPTFLAG_AND(permit_port_forwarding_flag);
+	OPTFLAG_AND(permit_agent_forwarding_flag);
+	OPTFLAG_AND(permit_x11_forwarding_flag);
+	OPTFLAG_AND(permit_pty_flag);
+	OPTFLAG_AND(permit_user_rc);
+	OPTFLAG_AND(no_require_user_presence);
+#undef OPTFLAG_AND
 
 	/* Earliest expiry time should win */
 	if (primary->valid_before != 0)
@@ -643,6 +649,7 @@ sshauthopt_copy(const struct sshauthopt *orig)
 	OPTSCALAR(cert_authority);
 	OPTSCALAR(force_tun_device);
 	OPTSCALAR(valid_before);
+	OPTSCALAR(no_require_user_presence);
 #undef OPTSCALAR
 #define OPTSTRING(x) \
 	do { \
@@ -765,7 +772,7 @@ sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
 {
 	int r = SSH_ERR_INTERNAL_ERROR;
 
-	/* Flag and simple integer options */
+	/* Flag options */
 	if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
 	    (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
 	    (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
@@ -773,7 +780,11 @@ sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
 	    (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
 	    (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
 	    (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
-	    (r = sshbuf_put_u64(m, opts->valid_before)) != 0)
+	    (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0)
+		return r;
+
+	/* Simple integer options */
+	if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
 		return r;
 
 	/* tunnel number can be negative to indicate "unset" */
@@ -817,6 +828,7 @@ sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
 	if ((opts = calloc(1, sizeof(*opts))) == NULL)
 		return SSH_ERR_ALLOC_FAIL;
 
+	/* Flag options */
 #define OPT_FLAG(x) \
 	do { \
 		if ((r = sshbuf_get_u8(m, &f)) != 0) \
@@ -830,8 +842,10 @@ sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
 	OPT_FLAG(permit_user_rc);
 	OPT_FLAG(restricted);
 	OPT_FLAG(cert_authority);
+	OPT_FLAG(no_require_user_presence);
 #undef OPT_FLAG
 
+	/* Simple integer options */
 	if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
 		goto out;
 
diff --git a/auth-options.h b/auth-options.h
index 14cbfa49d..d96ffedee 100644
--- a/auth-options.h
+++ b/auth-options.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.h,v 1.28 2019/07/09 04:15:00 djm Exp $ */
+/* $OpenBSD: auth-options.h,v 1.29 2019/11/25 00:54:23 djm Exp $ */
 
 /*
  * Copyright (c) 2018 Damien Miller <djm@mindrot.org>
@@ -68,6 +68,9 @@ struct sshauthopt {
 	 */
 	char *required_from_host_cert;
 	char *required_from_host_keys;
+
+	/* Key requires user presence asserted */
+	int no_require_user_presence;
 };
 
 struct sshauthopt *sshauthopt_new(void);
diff --git a/auth.c b/auth.c
index b092f212c..0a46e1d8a 100644
--- a/auth.c
+++ b/auth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.142 2019/10/16 06:05:39 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.143 2019/11/25 00:54:23 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -1005,7 +1005,7 @@ auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
 
 	snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
 	/* Try to keep this alphabetically sorted */
-	snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s",
+	snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
 	    opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
 	    opts->force_command == NULL ? "" : " command",
 	    do_env ?  " environment" : "",
@@ -1018,7 +1018,8 @@ auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
 	    opts->force_tun_device == -1 ? "" : " tun=",
 	    opts->force_tun_device == -1 ? "" : buf,
 	    opts->permit_user_rc ? " user-rc" : "",
-	    opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
+	    opts->permit_x11_forwarding_flag ? " x11-forwarding" : "",
+	    opts->no_require_user_presence ? " no-touch-required" : "");
 
 	debug("%s: %s", loc, msg);
 	if (do_remote)
diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index 0ef982a48..b656b1f8c 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.96 2019/11/25 00:52:46 djm Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.97 2019/11/25 00:54:23 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -225,7 +225,8 @@ userauth_pubkey(struct ssh *ssh)
 			    __func__, sig_details->sk_counter,
 			    sig_details->sk_flags);
 			req_presence = (options.pubkey_auth_options &
-			    PUBKEYAUTH_TOUCH_REQUIRED);
+			    PUBKEYAUTH_TOUCH_REQUIRED) ||
+			    !authopts->no_require_user_presence;
 			if (req_presence && (sig_details->sk_flags &
 			    SSH_SK_USER_PRESENCE_REQD) == 0) {
 				error("public key %s signature for %s%s from "
diff --git a/monitor.c b/monitor.c
index 9b171c447..d4be7409e 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.203 2019/11/25 00:52:46 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.204 2019/11/25 00:54:23 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -1440,7 +1440,8 @@ mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m)
 
 	if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) {
 		req_presence = (options.pubkey_auth_options &
-		    PUBKEYAUTH_TOUCH_REQUIRED);
+		    PUBKEYAUTH_TOUCH_REQUIRED) ||
+		    !key_opts->no_require_user_presence;
 		if (req_presence &&
 		    (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) {
 			error("public key %s %s signature for %s%s from %.128s "
diff --git a/ssh-keygen.1 b/ssh-keygen.1
index feaa69efe..06aead348 100644
--- a/ssh-keygen.1
+++ b/ssh-keygen.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ssh-keygen.1,v 1.176 2019/11/18 23:16:49 naddy Exp $
+.\"	$OpenBSD: ssh-keygen.1,v 1.177 2019/11/25 00:54:23 djm Exp $
 .\"
 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -35,7 +35,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: November 18 2019 $
+.Dd $Mdocdate: November 25 2019 $
 .Dt SSH-KEYGEN 1
 .Os
 .Sh NAME
@@ -534,6 +534,14 @@ by
 .It Ic permit-X11-forwarding
 Allows X11 forwarding.
 .Pp
+.It Ic no-touch-required
+Do not require signatures made using this key require demonstration
+of user presence (e.g. by having the user touch the key).
+This option only makes sense for the Security Key algorithms
+.Cm ecdsa-sk
+and
+.Cm ed25519-sk .
+.Pp
 .It Ic source-address Ns = Ns Ar address_list
 Restrict the source addresses from which the certificate is considered valid.
 The
diff --git a/ssh-keygen.c b/ssh-keygen.c
index 08dd7cb8a..16d196fc8 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.370 2019/11/25 00:51:37 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.371 2019/11/25 00:54:23 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -120,11 +120,12 @@ static u_int64_t cert_valid_from = 0;
 static u_int64_t cert_valid_to = ~0ULL;
 
 /* Certificate options */
-#define CERTOPT_X_FWD	(1)
-#define CERTOPT_AGENT_FWD	(1<<1)
-#define CERTOPT_PORT_FWD	(1<<2)
-#define CERTOPT_PTY		(1<<3)
-#define CERTOPT_USER_RC	(1<<4)
+#define CERTOPT_X_FWD				(1)
+#define CERTOPT_AGENT_FWD			(1<<1)
+#define CERTOPT_PORT_FWD			(1<<2)
+#define CERTOPT_PTY				(1<<3)
+#define CERTOPT_USER_RC				(1<<4)
+#define CERTOPT_NO_REQUIRE_USER_PRESENCE	(1<<5)
 #define CERTOPT_DEFAULT	(CERTOPT_X_FWD|CERTOPT_AGENT_FWD| \
 			 CERTOPT_PORT_FWD|CERTOPT_PTY|CERTOPT_USER_RC)
 static u_int32_t certflags_flags = CERTOPT_DEFAULT;
@@ -1665,6 +1666,9 @@ prepare_options_buf(struct sshbuf *c, int which)
 	if ((which & OPTIONS_EXTENSIONS) != 0 &&
 	    (certflags_flags & CERTOPT_USER_RC) != 0)
 		add_flag_option(c, "permit-user-rc");
+	if ((which & OPTIONS_CRITICAL) != 0 &&
+	    (certflags_flags & CERTOPT_NO_REQUIRE_USER_PRESENCE) != 0)
+		add_flag_option(c, "no-touch-required");
 	if ((which & OPTIONS_CRITICAL) != 0 &&
 	    certflags_src_addr != NULL)
 		add_string_option(c, "source-address", certflags_src_addr);
@@ -1967,6 +1971,10 @@ add_cert_option(char *opt)
 		certflags_flags &= ~CERTOPT_USER_RC;
 	else if (strcasecmp(opt, "permit-user-rc") == 0)
 		certflags_flags |= CERTOPT_USER_RC;
+	else if (strcasecmp(opt, "touch-required") == 0)
+		certflags_flags &= ~CERTOPT_NO_REQUIRE_USER_PRESENCE;
+	else if (strcasecmp(opt, "no-touch-required") == 0)
+		certflags_flags |= CERTOPT_NO_REQUIRE_USER_PRESENCE;
 	else if (strncasecmp(opt, "force-command=", 14) == 0) {
 		val = opt + 14;
 		if (*val == '\0')
@@ -2020,9 +2028,10 @@ show_options(struct sshbuf *optbuf, int in_critical)
 		    strcmp(name, "permit-agent-forwarding") == 0 ||
 		    strcmp(name, "permit-port-forwarding") == 0 ||
 		    strcmp(name, "permit-pty") == 0 ||
-		    strcmp(name, "permit-user-rc") == 0))
+		    strcmp(name, "permit-user-rc") == 0 ||
+		    strcmp(name, "no-touch-required") == 0)) {
 			printf("\n");
-		else if (in_critical &&
+		} else if (in_critical &&
 		    (strcmp(name, "force-command") == 0 ||
 		    strcmp(name, "source-address") == 0)) {
 			if ((r = sshbuf_get_cstring(option, &arg, NULL)) != 0)
diff --git a/sshd.8 b/sshd.8
index 042610a03..b32da282f 100644
--- a/sshd.8
+++ b/sshd.8
@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd.8,v 1.306 2019/11/18 04:55:02 djm Exp $
-.Dd $Mdocdate: November 18 2019 $
+.\" $OpenBSD: sshd.8,v 1.307 2019/11/25 00:54:23 djm Exp $
+.Dd $Mdocdate: November 25 2019 $
 .Dt SSHD 8
 .Os
 .Sh NAME
@@ -627,6 +627,13 @@ option.
 Permits tty allocation previously disabled by the
 .Cm restrict
 option.
+.It Cm no-touch-required
+Do not require demonstration of user presence
+for signatures made using this key.
+This option only makes sense for the Security Key algorithms
+.Cm ecdsa-sk
+and
+.Cm ed25519-sk .
 .It Cm restrict
 Enable all restrictions, i.e. disable port, agent and X11 forwarding,
 as well as disabling PTY allocation
@@ -670,6 +677,8 @@ restrict,command="uptime" ssh-rsa AAAA1C8...32Tv==
 user@example.net
 restrict,pty,command="nethack" ssh-rsa AAAA1f8...IrrC5==
 user@example.net
+no-touch-required sk-ecdsa-sha2-nistp256@openssh.com AAAAInN...Ko==
+user@example.net
 .Ed
 .Sh SSH_KNOWN_HOSTS FILE FORMAT
 The
-- 
cgit v1.2.3


From f65cf1163ff01531ae02f3f9210391d0d692f699 Mon Sep 17 00:00:00 2001
From: "tobhe@openbsd.org" <tobhe@openbsd.org>
Date: Mon, 16 Dec 2019 13:58:53 +0000
Subject: upstream: strdup may return NULL if memory allocation fails. Use

the safer xstrdup which fatals on allocation failures.

ok markus@

OpenBSD-Commit-ID: 8b608d387120630753cbcb8110e0b019c0c9a0d0
---
 auth.c   | 14 +++++++-------
 packet.c |  6 +++---
 2 files changed, 10 insertions(+), 10 deletions(-)

(limited to 'auth.c')

diff --git a/auth.c b/auth.c
index 0a46e1d8a..48838508e 100644
--- a/auth.c
+++ b/auth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.143 2019/11/25 00:54:23 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.144 2019/12/16 13:58:53 tobhe Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -748,7 +748,7 @@ remote_hostname(struct ssh *ssh)
 	if (getpeername(ssh_packet_get_connection_in(ssh),
 	    (struct sockaddr *)&from, &fromlen) == -1) {
 		debug("getpeername failed: %.100s", strerror(errno));
-		return strdup(ntop);
+		return xstrdup(ntop);
 	}
 
 	ipv64_normalise_mapped(&from, &fromlen);
@@ -760,7 +760,7 @@ remote_hostname(struct ssh *ssh)
 	if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
 	    NULL, 0, NI_NAMEREQD) != 0) {
 		/* Host name not found.  Use ip address. */
-		return strdup(ntop);
+		return xstrdup(ntop);
 	}
 
 	/*
@@ -775,7 +775,7 @@ remote_hostname(struct ssh *ssh)
 		logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
 		    name, ntop);
 		freeaddrinfo(ai);
-		return strdup(ntop);
+		return xstrdup(ntop);
 	}
 
 	/* Names are stored in lowercase. */
@@ -796,7 +796,7 @@ remote_hostname(struct ssh *ssh)
 	if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
 		logit("reverse mapping checking getaddrinfo for %.700s "
 		    "[%s] failed.", name, ntop);
-		return strdup(ntop);
+		return xstrdup(ntop);
 	}
 	/* Look for the address from the list of addresses. */
 	for (ai = aitop; ai; ai = ai->ai_next) {
@@ -811,9 +811,9 @@ remote_hostname(struct ssh *ssh)
 		/* Address not found for the host name. */
 		logit("Address %.100s maps to %.600s, but this does not "
 		    "map back to the address.", ntop, name);
-		return strdup(ntop);
+		return xstrdup(ntop);
 	}
-	return strdup(name);
+	return xstrdup(name);
 }
 
 /*
diff --git a/packet.c b/packet.c
index 7a703d695..2b50ef415 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.286 2019/06/28 13:35:04 deraadt Exp $ */
+/* $OpenBSD: packet.c,v 1.287 2019/12/16 13:58:53 tobhe Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -530,9 +530,9 @@ ssh_remote_ipaddr(struct ssh *ssh)
 			ssh->local_ipaddr = get_local_ipaddr(sock);
 			ssh->local_port = get_local_port(sock);
 		} else {
-			ssh->remote_ipaddr = strdup("UNKNOWN");
+			ssh->remote_ipaddr = xstrdup("UNKNOWN");
 			ssh->remote_port = 65535;
-			ssh->local_ipaddr = strdup("UNKNOWN");
+			ssh->local_ipaddr = xstrdup("UNKNOWN");
 			ssh->local_port = 65535;
 		}
 	}
-- 
cgit v1.2.3


From 3bf2a6ac791d64046a537335a0f1d5e43579c5ad Mon Sep 17 00:00:00 2001
From: "dtucker@openbsd.org" <dtucker@openbsd.org>
Date: Thu, 23 Jan 2020 07:10:22 +0000
Subject: upstream: Replace all calls to signal(2) with a wrapper around

sigaction(2). This wrapper blocks all other signals during the handler
preventing races between handlers, and sets SA_RESTART which should reduce
the potential for short read/write operations.

OpenBSD-Commit-ID: 5e047663fd77a40d7b07bdabe68529df51fd2519
---
 auth-pam.c                   |  8 ++++----
 auth.c                       |  4 ++--
 auth2-pubkey.c               | 10 +++++-----
 clientloop.c                 | 26 +++++++++++++-------------
 entropy.c                    |  4 ++--
 misc.c                       | 19 ++++++++++++++++++-
 misc.h                       |  4 +++-
 monitor.c                    | 10 +++++-----
 mux.c                        | 22 +++++++++++-----------
 openbsd-compat/bsd-openpty.c |  4 ++--
 progressmeter.c              |  6 +++---
 readconf.c                   |  4 ++--
 readpass.c                   | 14 +++++++-------
 sandbox-systrace.c           |  6 +++---
 scp.c                        | 22 +++++++++++-----------
 serverloop.c                 | 10 +++++-----
 session.c                    |  4 ++--
 sftp.c                       | 26 +++++++++++++-------------
 ssh-agent.c                  | 10 +++++-----
 ssh-sk-client.c              |  9 +++++----
 ssh.c                        |  6 +++---
 sshbuf.c                     |  4 ++--
 sshconnect.c                 | 10 +++++-----
 sshconnect2.c                |  8 ++++----
 sshd.c                       | 34 ++++++++++++++++++----------------
 25 files changed, 153 insertions(+), 131 deletions(-)

(limited to 'auth.c')

diff --git a/auth-pam.c b/auth-pam.c
index 856fdd40f..0cd2b0019 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -156,7 +156,7 @@ static mysig_t sshpam_oldsig;
 static void
 sshpam_sigchld_handler(int sig)
 {
-	signal(SIGCHLD, SIG_DFL);
+	ssh_signal(SIGCHLD, SIG_DFL);
 	if (cleanup_ctxt == NULL)
 		return;	/* handler called after PAM cleanup, shouldn't happen */
 	if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
@@ -208,7 +208,7 @@ pthread_create(sp_pthread_t *thread, const void *attr,
 		*thread = pid;
 		close(ctx->pam_csock);
 		ctx->pam_csock = -1;
-		sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
+		sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler);
 		return (0);
 	}
 }
@@ -216,7 +216,7 @@ pthread_create(sp_pthread_t *thread, const void *attr,
 static int
 pthread_cancel(sp_pthread_t thread)
 {
-	signal(SIGCHLD, sshpam_oldsig);
+	ssh_signal(SIGCHLD, sshpam_oldsig);
 	return (kill(thread, SIGTERM));
 }
 
@@ -228,7 +228,7 @@ pthread_join(sp_pthread_t thread, void **value)
 
 	if (sshpam_thread_status != -1)
 		return (sshpam_thread_status);
-	signal(SIGCHLD, sshpam_oldsig);
+	ssh_signal(SIGCHLD, sshpam_oldsig);
 	while (waitpid(thread, &status, 0) == -1) {
 		if (errno == EINTR)
 			continue;
diff --git a/auth.c b/auth.c
index 48838508e..b42d7e76c 100644
--- a/auth.c
+++ b/auth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.144 2019/12/16 13:58:53 tobhe Exp $ */
+/* $OpenBSD: auth.c,v 1.145 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -921,7 +921,7 @@ subprocess(const char *tag, struct passwd *pw, const char *command,
 			child_set_env(&child_env, &envsize, "LANG", cp);
 
 		for (i = 0; i < NSIG; i++)
-			signal(i, SIG_DFL);
+			ssh_signal(i, SIG_DFL);
 
 		if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 			error("%s: open %s: %s", tag, _PATH_DEVNULL,
diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index b656b1f8c..5b4a2cc02 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.97 2019/11/25 00:54:23 djm Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.98 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -460,7 +460,7 @@ match_principals_command(struct ssh *ssh, struct passwd *user_pw,
 	 * NB. all returns later this function should go via "out" to
 	 * ensure the original SIGCHLD handler is restored properly.
 	 */
-	osigchld = signal(SIGCHLD, SIG_DFL);
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
 
 	/* Prepare and verify the user for the command */
 	username = percent_expand(options.authorized_principals_command_user,
@@ -548,7 +548,7 @@ match_principals_command(struct ssh *ssh, struct passwd *user_pw,
  out:
 	if (f != NULL)
 		fclose(f);
-	signal(SIGCHLD, osigchld);
+	ssh_signal(SIGCHLD, osigchld);
 	for (i = 0; i < ac; i++)
 		free(av[i]);
 	free(av);
@@ -898,7 +898,7 @@ user_key_command_allowed2(struct ssh *ssh, struct passwd *user_pw,
 	 * NB. all returns later this function should go via "out" to
 	 * ensure the original SIGCHLD handler is restored properly.
 	 */
-	osigchld = signal(SIGCHLD, SIG_DFL);
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
 
 	/* Prepare and verify the user for the command */
 	username = percent_expand(options.authorized_keys_command_user,
@@ -987,7 +987,7 @@ user_key_command_allowed2(struct ssh *ssh, struct passwd *user_pw,
  out:
 	if (f != NULL)
 		fclose(f);
-	signal(SIGCHLD, osigchld);
+	ssh_signal(SIGCHLD, osigchld);
 	for (i = 0; i < ac; i++)
 		free(av[i]);
 	free(av);
diff --git a/clientloop.c b/clientloop.c
index 4acf2806d..d4c23d554 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.331 2020/01/23 02:46:49 dtucker Exp $ */
+/* $OpenBSD: clientloop.c,v 1.332 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -785,7 +785,7 @@ process_cmdline(struct ssh *ssh)
 	memset(&fwd, 0, sizeof(fwd));
 
 	leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
-	handler = signal(SIGINT, SIG_IGN);
+	handler = ssh_signal(SIGINT, SIG_IGN);
 	cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
 	if (s == NULL)
 		goto out;
@@ -883,7 +883,7 @@ process_cmdline(struct ssh *ssh)
 	}
 
 out:
-	signal(SIGINT, handler);
+	ssh_signal(SIGINT, handler);
 	enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
 	free(cmd);
 	free(fwd.listen_host);
@@ -1306,15 +1306,15 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
 	 * Set signal handlers, (e.g. to restore non-blocking mode)
 	 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
 	 */
-	if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
-		signal(SIGHUP, signal_handler);
-	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
-		signal(SIGINT, signal_handler);
-	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
-		signal(SIGQUIT, signal_handler);
-	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
-		signal(SIGTERM, signal_handler);
-	signal(SIGWINCH, window_change_handler);
+	if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN)
+		ssh_signal(SIGHUP, signal_handler);
+	if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN)
+		ssh_signal(SIGINT, signal_handler);
+	if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN)
+		ssh_signal(SIGQUIT, signal_handler);
+	if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN)
+		ssh_signal(SIGTERM, signal_handler);
+	ssh_signal(SIGWINCH, window_change_handler);
 
 	if (have_pty)
 		enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
@@ -1413,7 +1413,7 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
 	/* Terminate the session. */
 
 	/* Stop watching for window change. */
-	signal(SIGWINCH, SIG_DFL);
+	ssh_signal(SIGWINCH, SIG_DFL);
 
 	if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
 	    (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 ||
diff --git a/entropy.c b/entropy.c
index 5de68016b..2eebadf4a 100644
--- a/entropy.c
+++ b/entropy.c
@@ -110,7 +110,7 @@ get_random_bytes_prngd(unsigned char *buf, int len,
 		    strlen(socket_path) + 1;
 	}
 
-	old_sigpipe = signal(SIGPIPE, SIG_IGN);
+	old_sigpipe = ssh_signal(SIGPIPE, SIG_IGN);
 
 	errors = 0;
 	rval = -1;
@@ -160,7 +160,7 @@ reopen:
 
 	rval = 0;
 done:
-	signal(SIGPIPE, old_sigpipe);
+	ssh_signal(SIGPIPE, old_sigpipe);
 	if (fd != -1)
 		close(fd);
 	return rval;
diff --git a/misc.c b/misc.c
index 5204c1e9f..f25b8cf5c 100644
--- a/misc.c
+++ b/misc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.c,v 1.143 2019/11/22 06:50:30 dtucker Exp $ */
+/* $OpenBSD: misc.c,v 1.144 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
@@ -2221,3 +2221,20 @@ opt_match(const char **opts, const char *term)
 	return 0;
 }
 
+sshsig_t
+ssh_signal(int signum, sshsig_t handler)
+{
+	struct sigaction sa, osa;
+
+	/* mask all other signals while in handler */
+	bzero(&sa, sizeof(sa));
+	sa.sa_handler = handler;
+	sigfillset(&sa.sa_mask);
+	if (signum != SIGALRM)
+		sa.sa_flags = SA_RESTART;
+	if (sigaction(signum, &sa, &osa) == -1) {
+		debug3("sigaction(%s): %s", strsignal(signum), strerror(errno));
+		return SIG_ERR;
+	}
+	return osa.sa_handler;
+}
diff --git a/misc.h b/misc.h
index 7421fbdf9..2221a54c8 100644
--- a/misc.h
+++ b/misc.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.h,v 1.82 2019/11/12 22:34:20 djm Exp $ */
+/* $OpenBSD: misc.h,v 1.83 2020/01/23 07:10:22 dtucker Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -190,4 +190,6 @@ void	notify_complete(struct notifier_ctx *);
 #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
 #define ROUNDUP(x, y)   ((((x)+((y)-1))/(y))*(y))
 
+typedef void (*sshsig_t)(int);
+sshsig_t ssh_signal(int, sshsig_t);
 #endif /* _MISC_H */
diff --git a/monitor.c b/monitor.c
index 6ee44204c..dc6d78d3c 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.206 2019/12/15 18:57:30 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.207 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -393,11 +393,11 @@ monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
 	pmonitor->m_recvfd = -1;
 
 	monitor_set_child_handler(pmonitor->m_pid);
-	signal(SIGHUP, &monitor_child_handler);
-	signal(SIGTERM, &monitor_child_handler);
-	signal(SIGINT, &monitor_child_handler);
+	ssh_signal(SIGHUP, &monitor_child_handler);
+	ssh_signal(SIGTERM, &monitor_child_handler);
+	ssh_signal(SIGINT, &monitor_child_handler);
 #ifdef SIGXFSZ
-	signal(SIGXFSZ, SIG_IGN);
+	ssh_signal(SIGXFSZ, SIG_IGN);
 #endif
 
 	mon_dispatch = mon_dispatch_postauth20;
diff --git a/mux.c b/mux.c
index f3ea11cdc..5efc849c4 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.80 2019/06/28 13:35:04 deraadt Exp $ */
+/* $OpenBSD: mux.c,v 1.81 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
@@ -1911,7 +1911,7 @@ mux_client_request_session(int fd)
 		return -1;
 	}
 
-	signal(SIGPIPE, SIG_IGN);
+	ssh_signal(SIGPIPE, SIG_IGN);
 
 	if (stdin_null_flag) {
 		if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
@@ -2012,10 +2012,10 @@ mux_client_request_session(int fd)
 		fatal("%s pledge(): %s", __func__, strerror(errno));
 	platform_pledge_mux();
 
-	signal(SIGHUP, control_client_sighandler);
-	signal(SIGINT, control_client_sighandler);
-	signal(SIGTERM, control_client_sighandler);
-	signal(SIGWINCH, control_client_sigrelay);
+	ssh_signal(SIGHUP, control_client_sighandler);
+	ssh_signal(SIGINT, control_client_sighandler);
+	ssh_signal(SIGTERM, control_client_sighandler);
+	ssh_signal(SIGWINCH, control_client_sigrelay);
 
 	rawmode = tty_flag;
 	if (tty_flag)
@@ -2145,7 +2145,7 @@ mux_client_request_stdio_fwd(int fd)
 		return -1;
 	}
 
-	signal(SIGPIPE, SIG_IGN);
+	ssh_signal(SIGPIPE, SIG_IGN);
 
 	if (stdin_null_flag) {
 		if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
@@ -2219,10 +2219,10 @@ mux_client_request_stdio_fwd(int fd)
 	}
 	muxclient_request_id++;
 
-	signal(SIGHUP, control_client_sighandler);
-	signal(SIGINT, control_client_sighandler);
-	signal(SIGTERM, control_client_sighandler);
-	signal(SIGWINCH, control_client_sigrelay);
+	ssh_signal(SIGHUP, control_client_sighandler);
+	ssh_signal(SIGINT, control_client_sighandler);
+	ssh_signal(SIGTERM, control_client_sighandler);
+	ssh_signal(SIGWINCH, control_client_sigrelay);
 
 	/*
 	 * Stick around until the controlee closes the client_fd.
diff --git a/openbsd-compat/bsd-openpty.c b/openbsd-compat/bsd-openpty.c
index 123a9be56..b6b5ab49b 100644
--- a/openbsd-compat/bsd-openpty.c
+++ b/openbsd-compat/bsd-openpty.c
@@ -103,10 +103,10 @@ openpty(int *amaster, int *aslave, char *name, struct termios *termp,
 		return (-1);
 
 	/* XXX: need to close ptm on error? */
-	old_signal = signal(SIGCHLD, SIG_DFL);
+	old_signal = ssh_signal(SIGCHLD, SIG_DFL);
 	if (grantpt(ptm) < 0)
 		return (-1);
-	signal(SIGCHLD, old_signal);
+	ssh_signal(SIGCHLD, old_signal);
 
 	if (unlockpt(ptm) < 0)
 		return (-1);
diff --git a/progressmeter.c b/progressmeter.c
index 72f40f8f9..8baf798f1 100644
--- a/progressmeter.c
+++ b/progressmeter.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: progressmeter.c,v 1.49 2019/10/29 07:47:27 dtucker Exp $ */
+/* $OpenBSD: progressmeter.c,v 1.50 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2003 Nils Nordman.  All rights reserved.
  *
@@ -252,8 +252,8 @@ start_progress_meter(const char *f, off_t filesize, off_t *ctr)
 	setscreensize();
 	refresh_progress_meter(1);
 
-	signal(SIGALRM, sig_alarm);
-	signal(SIGWINCH, sig_winch);
+	ssh_signal(SIGALRM, sig_alarm);
+	ssh_signal(SIGWINCH, sig_winch);
 	alarm(UPDATE_INTERVAL);
 }
 
diff --git a/readconf.c b/readconf.c
index ff551c856..59443bfdb 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.320 2020/01/23 02:46:49 dtucker Exp $ */
+/* $OpenBSD: readconf.c,v 1.321 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -528,7 +528,7 @@ execute_in_shell(const char *cmd)
 		execv(argv[0], argv);
 		error("Unable to execute '%.100s': %s", cmd, strerror(errno));
 		/* Die with signal to make this error apparent to parent. */
-		signal(SIGTERM, SIG_DFL);
+		ssh_signal(SIGTERM, SIG_DFL);
 		kill(getpid(), SIGTERM);
 		_exit(1);
 	}
diff --git a/readpass.c b/readpass.c
index 4172bbc56..974d67f0b 100644
--- a/readpass.c
+++ b/readpass.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readpass.c,v 1.60 2019/12/06 03:06:08 djm Exp $ */
+/* $OpenBSD: readpass.c,v 1.61 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  *
@@ -65,10 +65,10 @@ ssh_askpass(char *askpass, const char *msg, const char *env_hint)
 		error("%s: pipe: %s", __func__, strerror(errno));
 		return NULL;
 	}
-	osigchld = signal(SIGCHLD, SIG_DFL);
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
 	if ((pid = fork()) == -1) {
 		error("%s: fork: %s", __func__, strerror(errno));
-		signal(SIGCHLD, osigchld);
+		ssh_signal(SIGCHLD, osigchld);
 		return NULL;
 	}
 	if (pid == 0) {
@@ -98,7 +98,7 @@ ssh_askpass(char *askpass, const char *msg, const char *env_hint)
 	while ((ret = waitpid(pid, &status, 0)) == -1)
 		if (errno != EINTR)
 			break;
-	signal(SIGCHLD, osigchld);
+	ssh_signal(SIGCHLD, osigchld);
 	if (ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 		explicit_bzero(buf, sizeof(buf));
 		return NULL;
@@ -243,10 +243,10 @@ notify_start(int force_askpass, const char *fmt, ...)
 		free(prompt);
 		return NULL;
 	}
-	osigchld = signal(SIGCHLD, SIG_DFL);
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
 	if ((pid = fork()) == -1) {
 		error("%s: fork: %s", __func__, strerror(errno));
-		signal(SIGCHLD, osigchld);
+		ssh_signal(SIGCHLD, osigchld);
 		free(prompt);
 		return NULL;
 	}
@@ -289,6 +289,6 @@ notify_complete(struct notifier_ctx *ctx)
 	}
 	if (ret == -1)
 		fatal("%s: waitpid: %s", __func__, strerror(errno));
-	signal(SIGCHLD, ctx->osigchld);
+	ssh_signal(SIGCHLD, ctx->osigchld);
 	free(ctx);
 }
diff --git a/sandbox-systrace.c b/sandbox-systrace.c
index 93e63b8e0..e61d581ae 100644
--- a/sandbox-systrace.c
+++ b/sandbox-systrace.c
@@ -105,7 +105,7 @@ ssh_sandbox_init(struct monitor *monitor)
 	box = xcalloc(1, sizeof(*box));
 	box->systrace_fd = -1;
 	box->child_pid = 0;
-	box->osigchld = signal(SIGCHLD, SIG_IGN);
+	box->osigchld = ssh_signal(SIGCHLD, SIG_IGN);
 
 	return box;
 }
@@ -114,7 +114,7 @@ void
 ssh_sandbox_child(struct ssh_sandbox *box)
 {
 	debug3("%s: ready", __func__);
-	signal(SIGCHLD, box->osigchld);
+	ssh_signal(SIGCHLD, box->osigchld);
 	if (kill(getpid(), SIGSTOP) != 0)
 		fatal("%s: kill(%d, SIGSTOP)", __func__, getpid());
 	debug3("%s: started", __func__);
@@ -133,7 +133,7 @@ ssh_sandbox_parent(struct ssh_sandbox *box, pid_t child_pid,
 	do {
 		pid = waitpid(child_pid, &status, WUNTRACED);
 	} while (pid == -1 && errno == EINTR);
-	signal(SIGCHLD, box->osigchld);
+	ssh_signal(SIGCHLD, box->osigchld);
 	if (!WIFSTOPPED(status)) {
 		if (WIFSIGNALED(status))
 			fatal("%s: child terminated with signal %d",
diff --git a/scp.c b/scp.c
index 762286c73..6901e0c94 100644
--- a/scp.c
+++ b/scp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: scp.c,v 1.206 2019/09/09 02:31:19 dtucker Exp $ */
+/* $OpenBSD: scp.c,v 1.207 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * scp - secure remote copy.  This is basically patched BSD rcp which
  * uses ssh to do the data transfer (instead of using rcmd).
@@ -215,9 +215,9 @@ do_local_cmd(arglist *a)
 	}
 
 	do_cmd_pid = pid;
-	signal(SIGTERM, killchild);
-	signal(SIGINT, killchild);
-	signal(SIGHUP, killchild);
+	ssh_signal(SIGTERM, killchild);
+	ssh_signal(SIGINT, killchild);
+	ssh_signal(SIGHUP, killchild);
 
 	while (waitpid(pid, &status, 0) == -1)
 		if (errno != EINTR)
@@ -268,9 +268,9 @@ do_cmd(char *host, char *remuser, int port, char *cmd, int *fdin, int *fdout)
 	close(reserved[0]);
 	close(reserved[1]);
 
-	signal(SIGTSTP, suspchild);
-	signal(SIGTTIN, suspchild);
-	signal(SIGTTOU, suspchild);
+	ssh_signal(SIGTSTP, suspchild);
+	ssh_signal(SIGTTIN, suspchild);
+	ssh_signal(SIGTTOU, suspchild);
 
 	/* Fork a child to execute the command on the remote host using ssh. */
 	do_cmd_pid = fork();
@@ -307,9 +307,9 @@ do_cmd(char *host, char *remuser, int port, char *cmd, int *fdin, int *fdout)
 	*fdout = pin[1];
 	close(pout[1]);
 	*fdin = pout[0];
-	signal(SIGTERM, killchild);
-	signal(SIGINT, killchild);
-	signal(SIGHUP, killchild);
+	ssh_signal(SIGTERM, killchild);
+	ssh_signal(SIGINT, killchild);
+	ssh_signal(SIGHUP, killchild);
 	return 0;
 }
 
@@ -561,7 +561,7 @@ main(int argc, char **argv)
 	    iamrecursive ? " -r" : "", pflag ? " -p" : "",
 	    targetshouldbedirectory ? " -d" : "");
 
-	(void) signal(SIGPIPE, lostconn);
+	(void) ssh_signal(SIGPIPE, lostconn);
 
 	if (colon(argv[argc - 1]))	/* Dest is remote host. */
 		toremote(argc, argv);
diff --git a/serverloop.c b/serverloop.c
index 99d259201..1babc7a51 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.218 2019/11/27 05:38:43 dtucker Exp $ */
+/* $OpenBSD: serverloop.c,v 1.219 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -402,15 +402,15 @@ server_loop2(struct ssh *ssh, Authctxt *authctxt)
 
 	debug("Entering interactive session for SSH2.");
 
-	signal(SIGCHLD, sigchld_handler);
+	ssh_signal(SIGCHLD, sigchld_handler);
 	child_terminated = 0;
 	connection_in = ssh_packet_get_connection_in(ssh);
 	connection_out = ssh_packet_get_connection_out(ssh);
 
 	if (!use_privsep) {
-		signal(SIGTERM, sigterm_handler);
-		signal(SIGINT, sigterm_handler);
-		signal(SIGQUIT, sigterm_handler);
+		ssh_signal(SIGTERM, sigterm_handler);
+		ssh_signal(SIGINT, sigterm_handler);
+		ssh_signal(SIGQUIT, sigterm_handler);
 	}
 
 	notify_setup();
diff --git a/session.c b/session.c
index e16f876c5..8c0e54f79 100644
--- a/session.c
+++ b/session.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.317 2019/11/13 04:47:52 deraadt Exp $ */
+/* $OpenBSD: session.c,v 1.318 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -1642,7 +1642,7 @@ do_child(struct ssh *ssh, Session *s, const char *command)
 	do_rc_files(ssh, s, shell);
 
 	/* restore SIGPIPE for child */
-	signal(SIGPIPE, SIG_DFL);
+	ssh_signal(SIGPIPE, SIG_DFL);
 
 	if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) {
 		error("Connection from %s: refusing non-sftp session",
diff --git a/sftp.c b/sftp.c
index 54538ff96..ff14d3c29 100644
--- a/sftp.c
+++ b/sftp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sftp.c,v 1.196 2019/11/01 03:54:33 djm Exp $ */
+/* $OpenBSD: sftp.c,v 1.197 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2001-2004 Damien Miller <djm@openbsd.org>
  *
@@ -2243,7 +2243,7 @@ interactive_loop(struct sftp_conn *conn, char *file1, char *file2)
 	interactive = !batchmode && isatty(STDIN_FILENO);
 	err = 0;
 	for (;;) {
-		signal(SIGINT, SIG_IGN);
+		ssh_signal(SIGINT, SIG_IGN);
 
 		if (el == NULL) {
 			if (interactive)
@@ -2275,14 +2275,14 @@ interactive_loop(struct sftp_conn *conn, char *file1, char *file2)
 
 		/* Handle user interrupts gracefully during commands */
 		interrupted = 0;
-		signal(SIGINT, cmd_interrupt);
+		ssh_signal(SIGINT, cmd_interrupt);
 
 		err = parse_dispatch_command(conn, cmd, &remote_path,
 		    startdir, batchmode, !interactive && el == NULL);
 		if (err != 0)
 			break;
 	}
-	signal(SIGCHLD, SIG_DFL);
+	ssh_signal(SIGCHLD, SIG_DFL);
 	free(remote_path);
 	free(startdir);
 	free(conn);
@@ -2339,20 +2339,20 @@ connect_to_server(char *path, char **args, int *in, int *out)
 		 * kill it too.  Contrawise, since sftp sends SIGTERMs to the
 		 * underlying ssh, it must *not* ignore that signal.
 		 */
-		signal(SIGINT, SIG_IGN);
-		signal(SIGTERM, SIG_DFL);
+		ssh_signal(SIGINT, SIG_IGN);
+		ssh_signal(SIGTERM, SIG_DFL);
 		execvp(path, args);
 		fprintf(stderr, "exec: %s: %s\n", path, strerror(errno));
 		_exit(1);
 	}
 
-	signal(SIGTERM, killchild);
-	signal(SIGINT, killchild);
-	signal(SIGHUP, killchild);
-	signal(SIGTSTP, suspchild);
-	signal(SIGTTIN, suspchild);
-	signal(SIGTTOU, suspchild);
-	signal(SIGCHLD, sigchld_handler);
+	ssh_signal(SIGTERM, killchild);
+	ssh_signal(SIGINT, killchild);
+	ssh_signal(SIGHUP, killchild);
+	ssh_signal(SIGTSTP, suspchild);
+	ssh_signal(SIGTTIN, suspchild);
+	ssh_signal(SIGTTOU, suspchild);
+	ssh_signal(SIGCHLD, sigchld_handler);
 	close(c_in);
 	close(c_out);
 }
diff --git a/ssh-agent.c b/ssh-agent.c
index 09d12dc3f..dd5d21d5a 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-agent.c,v 1.251 2019/12/13 19:09:10 djm Exp $ */
+/* $OpenBSD: ssh-agent.c,v 1.252 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1404,10 +1404,10 @@ skip:
 	if (ac > 0)
 		parent_alive_interval = 10;
 	idtab_init();
-	signal(SIGPIPE, SIG_IGN);
-	signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
-	signal(SIGHUP, cleanup_handler);
-	signal(SIGTERM, cleanup_handler);
+	ssh_signal(SIGPIPE, SIG_IGN);
+	ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
+	ssh_signal(SIGHUP, cleanup_handler);
+	ssh_signal(SIGTERM, cleanup_handler);
 
 	if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1)
 		fatal("%s: pledge: %s", __progname, strerror(errno));
diff --git a/ssh-sk-client.c b/ssh-sk-client.c
index 359327b68..8d7e6c305 100644
--- a/ssh-sk-client.c
+++ b/ssh-sk-client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-sk-client.c,v 1.6 2020/01/21 07:07:31 djm Exp $ */
+/* $OpenBSD: ssh-sk-client.c,v 1.7 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -39,6 +39,7 @@
 #include "digest.h"
 #include "pathnames.h"
 #include "ssh-sk.h"
+#include "misc.h"
 
 /* #define DEBUG_SK 1 */
 
@@ -73,13 +74,13 @@ start_helper(int *fdp, pid_t *pidp, void (**osigchldp)(int))
 		error("socketpair: %s", strerror(errno));
 		return SSH_ERR_SYSTEM_ERROR;
 	}
-	osigchld = signal(SIGCHLD, SIG_DFL);
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
 	if ((pid = fork()) == -1) {
 		oerrno = errno;
 		error("fork: %s", strerror(errno));
 		close(pair[0]);
 		close(pair[1]);
-		signal(SIGCHLD, osigchld);
+		ssh_signal(SIGCHLD, osigchld);
 		errno = oerrno;
 		return SSH_ERR_SYSTEM_ERROR;
 	}
@@ -220,7 +221,7 @@ client_converse(struct sshbuf *msg, struct sshbuf **respp, u_int type)
 	}
 	sshbuf_free(req);
 	sshbuf_free(resp);
-	signal(SIGCHLD, osigchld);
+	ssh_signal(SIGCHLD, osigchld);
 	errno = oerrno;
 	return r;
 
diff --git a/ssh.c b/ssh.c
index 947558d1c..c0511f2a0 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.511 2020/01/05 16:28:22 beck Exp $ */
+/* $OpenBSD: ssh.c,v 1.512 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1535,8 +1535,8 @@ main(int ac, char **av)
 	    options.num_system_hostfiles);
 	tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 
-	signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
-	signal(SIGCHLD, main_sigchld_handler);
+	ssh_signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
+	ssh_signal(SIGCHLD, main_sigchld_handler);
 
 	/* Log into the remote system.  Never returns if the login fails. */
 	ssh_login(ssh, &sensitive_data, host, (struct sockaddr *)&hostaddr,
diff --git a/sshbuf.c b/sshbuf.c
index adfddf775..f4f7a220f 100644
--- a/sshbuf.c
+++ b/sshbuf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sshbuf.c,v 1.13 2018/11/16 06:10:29 djm Exp $	*/
+/*	$OpenBSD: sshbuf.c,v 1.14 2020/01/23 07:10:22 dtucker Exp $	*/
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -42,7 +42,7 @@ sshbuf_check_sanity(const struct sshbuf *buf)
 	    buf->off > buf->size)) {
 		/* Do not try to recover from corrupted buffer internals */
 		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
-		signal(SIGSEGV, SIG_DFL);
+		ssh_signal(SIGSEGV, SIG_DFL);
 		raise(SIGSEGV);
 		return SSH_ERR_INTERNAL_ERROR;
 	}
diff --git a/sshconnect.c b/sshconnect.c
index a2d759819..690240716 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.326 2020/01/22 07:38:30 dtucker Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.327 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -259,7 +259,7 @@ ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
 
 		/* Execute the proxy command.  Note that we gave up any
 		   extra privileges above. */
-		signal(SIGPIPE, SIG_DFL);
+		ssh_signal(SIGPIPE, SIG_DFL);
 		execv(argv[0], argv);
 		perror(argv[0]);
 		exit(1);
@@ -1383,10 +1383,10 @@ ssh_local_cmd(const char *args)
 	if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
 		shell = _PATH_BSHELL;
 
-	osighand = signal(SIGCHLD, SIG_DFL);
+	osighand = ssh_signal(SIGCHLD, SIG_DFL);
 	pid = fork();
 	if (pid == 0) {
-		signal(SIGPIPE, SIG_DFL);
+		ssh_signal(SIGPIPE, SIG_DFL);
 		debug3("Executing %s -c \"%s\"", shell, args);
 		execl(shell, shell, "-c", args, (char *)NULL);
 		error("Couldn't execute %s -c \"%s\": %s",
@@ -1397,7 +1397,7 @@ ssh_local_cmd(const char *args)
 	while (waitpid(pid, &status, 0) == -1)
 		if (errno != EINTR)
 			fatal("Couldn't wait for child: %s", strerror(errno));
-	signal(SIGCHLD, osighand);
+	ssh_signal(SIGCHLD, osighand);
 
 	if (!WIFEXITED(status))
 		return (1);
diff --git a/sshconnect2.c b/sshconnect2.c
index 7f52cc55e..8d13310f2 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.316 2020/01/23 02:46:49 dtucker Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.317 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -1924,7 +1924,7 @@ ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
 		error("%s: fork: %s", __func__, strerror(errno));
 		return -1;
 	}
-	osigchld = signal(SIGCHLD, SIG_DFL);
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
 	if (pid == 0) {
 		close(from[0]);
 		if (dup2(from[1], STDOUT_FILENO) == -1)
@@ -1996,11 +1996,11 @@ ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
 	if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
 		error("%s: buffer error: %s", __func__, ssh_err(r));
  fail:
-		signal(SIGCHLD, osigchld);
+		ssh_signal(SIGCHLD, osigchld);
 		sshbuf_free(b);
 		return -1;
 	}
-	signal(SIGCHLD, osigchld);
+	ssh_signal(SIGCHLD, osigchld);
 	sshbuf_free(b);
 
 	return 0;
diff --git a/sshd.c b/sshd.c
index 46f693a8e..c447edfe1 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.543 2020/01/21 22:39:57 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.544 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -313,7 +313,7 @@ sighup_restart(void)
 	close_listen_socks();
 	close_startup_pipes();
 	alarm(0);  /* alarm timer persists across exec */
-	signal(SIGHUP, SIG_IGN); /* will be restored after exec */
+	ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */
 	execv(saved_argv[0], saved_argv);
 	logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
 	    strerror(errno));
@@ -342,6 +342,8 @@ main_sigchld_handler(int sig)
 	pid_t pid;
 	int status;
 
+	debug("main_sigchld_handler: %s", strsignal(sig));
+
 	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
 	    (pid == -1 && errno == EINTR))
 		;
@@ -363,7 +365,7 @@ grace_alarm_handler(int sig)
 	 * keys command helpers.
 	 */
 	if (getpgid(0) == getpid()) {
-		signal(SIGTERM, SIG_IGN);
+		ssh_signal(SIGTERM, SIG_IGN);
 		kill(0, SIGTERM);
 	}
 
@@ -1941,7 +1943,7 @@ main(int ac, char **av)
 		error("chdir(\"/\"): %s", strerror(errno));
 
 	/* ignore SIGPIPE */
-	signal(SIGPIPE, SIG_IGN);
+	ssh_signal(SIGPIPE, SIG_IGN);
 
 	/* Get a connection, either from inetd or a listening TCP socket */
 	if (inetd_flag) {
@@ -1950,10 +1952,10 @@ main(int ac, char **av)
 		platform_pre_listen();
 		server_listen();
 
-		signal(SIGHUP, sighup_handler);
-		signal(SIGCHLD, main_sigchld_handler);
-		signal(SIGTERM, sigterm_handler);
-		signal(SIGQUIT, sigterm_handler);
+		ssh_signal(SIGHUP, sighup_handler);
+		ssh_signal(SIGCHLD, main_sigchld_handler);
+		ssh_signal(SIGTERM, sigterm_handler);
+		ssh_signal(SIGQUIT, sigterm_handler);
 
 		/*
 		 * Write out the pid file after the sigterm handler
@@ -2043,12 +2045,12 @@ main(int ac, char **av)
 	 * will not restart on SIGHUP since it no longer makes sense.
 	 */
 	alarm(0);
-	signal(SIGALRM, SIG_DFL);
-	signal(SIGHUP, SIG_DFL);
-	signal(SIGTERM, SIG_DFL);
-	signal(SIGQUIT, SIG_DFL);
-	signal(SIGCHLD, SIG_DFL);
-	signal(SIGINT, SIG_DFL);
+	ssh_signal(SIGALRM, SIG_DFL);
+	ssh_signal(SIGHUP, SIG_DFL);
+	ssh_signal(SIGTERM, SIG_DFL);
+	ssh_signal(SIGQUIT, SIG_DFL);
+	ssh_signal(SIGCHLD, SIG_DFL);
+	ssh_signal(SIGINT, SIG_DFL);
 
 	/*
 	 * Register our connection.  This turns encryption off because we do
@@ -2109,7 +2111,7 @@ main(int ac, char **av)
 	 * mode; it is just annoying to have the server exit just when you
 	 * are about to discover the bug.
 	 */
-	signal(SIGALRM, grace_alarm_handler);
+	ssh_signal(SIGALRM, grace_alarm_handler);
 	if (!debug_flag)
 		alarm(options.login_grace_time);
 
@@ -2167,7 +2169,7 @@ main(int ac, char **av)
 	 * authentication.
 	 */
 	alarm(0);
-	signal(SIGALRM, SIG_DFL);
+	ssh_signal(SIGALRM, SIG_DFL);
 	authctxt->authenticated = 1;
 	if (startup_pipe != -1) {
 		close(startup_pipe);
-- 
cgit v1.2.3


From c2bd7f74b0e0f3a3ee9d19ac549e6ba89013abaf Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Fri, 31 Jan 2020 22:42:45 +0000
Subject: upstream: Add a sshd_config "Include" directive to allow inclusion

of files. This has sensible semantics wrt Match blocks and accepts glob(3)
patterns to specify the included files. Based on patch by Jakub Jelen in
bz2468; feedback and ok markus@

OpenBSD-Commit-ID: 36ed0e845b872e33f03355b936a4fff02d5794ff
---
 auth.c        |   5 +-
 servconf.c    | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++-------
 servconf.h    |  20 +++++--
 sshd.c        |  65 +++++++++++++++++------
 sshd_config.5 |  19 +++++--
 5 files changed, 232 insertions(+), 44 deletions(-)

(limited to 'auth.c')

diff --git a/auth.c b/auth.c
index b42d7e76c..086b8ebb1 100644
--- a/auth.c
+++ b/auth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.145 2020/01/23 07:10:22 dtucker Exp $ */
+/* $OpenBSD: auth.c,v 1.146 2020/01/31 22:42:45 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -79,6 +79,7 @@
 
 /* import */
 extern ServerOptions options;
+extern struct include_list includes;
 extern int use_privsep;
 extern struct sshbuf *loginmsg;
 extern struct passwd *privsep_pw;
@@ -571,7 +572,7 @@ getpwnamallow(struct ssh *ssh, const char *user)
 
 	ci = get_connection_info(ssh, 1, options.use_dns);
 	ci->user = user;
-	parse_server_match_config(&options, ci);
+	parse_server_match_config(&options, &includes, ci);
 	log_change_level(options.log_level);
 	process_permitopen(ssh, &options);
 
diff --git a/servconf.c b/servconf.c
index 1e0718139..70f5f73f0 100644
--- a/servconf.c
+++ b/servconf.c
@@ -1,5 +1,5 @@
 
-/* $OpenBSD: servconf.c,v 1.359 2020/01/23 10:24:29 dtucker Exp $ */
+/* $OpenBSD: servconf.c,v 1.360 2020/01/31 22:42:45 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -40,6 +40,11 @@
 #ifdef HAVE_UTIL_H
 #include <util.h>
 #endif
+#ifdef USE_SYSTEM_GLOB
+# include <glob.h>
+#else
+# include "openbsd-compat/glob.h"
+#endif
 
 #include "openbsd-compat/sys-queue.h"
 #include "xmalloc.h"
@@ -69,6 +74,9 @@ static void add_listen_addr(ServerOptions *, const char *,
     const char *, int);
 static void add_one_listen_addr(ServerOptions *, const char *,
     const char *, int);
+void parse_server_config_depth(ServerOptions *options, const char *filename,
+    struct sshbuf *conf, struct include_list *includes,
+    struct connection_info *connectinfo, int flags, int *activep, int depth);
 
 /* Use of privilege separation or not */
 extern int use_privsep;
@@ -526,7 +534,7 @@ typedef enum {
 	sAcceptEnv, sSetEnv, sPermitTunnel,
 	sMatch, sPermitOpen, sPermitListen, sForceCommand, sChrootDirectory,
 	sUsePrivilegeSeparation, sAllowAgentForwarding,
-	sHostCertificate,
+	sHostCertificate, sInclude,
 	sRevokedKeys, sTrustedUserCAKeys, sAuthorizedPrincipalsFile,
 	sAuthorizedPrincipalsCommand, sAuthorizedPrincipalsCommandUser,
 	sKexAlgorithms, sCASignatureAlgorithms, sIPQoS, sVersionAddendum,
@@ -538,9 +546,10 @@ typedef enum {
 	sDeprecated, sIgnore, sUnsupported
 } ServerOpCodes;
 
-#define SSHCFG_GLOBAL	0x01	/* allowed in main section of sshd_config */
-#define SSHCFG_MATCH	0x02	/* allowed inside a Match section */
-#define SSHCFG_ALL	(SSHCFG_GLOBAL|SSHCFG_MATCH)
+#define SSHCFG_GLOBAL		0x01	/* allowed in main section of config */
+#define SSHCFG_MATCH		0x02	/* allowed inside a Match section */
+#define SSHCFG_ALL		(SSHCFG_GLOBAL|SSHCFG_MATCH)
+#define SSHCFG_NEVERMATCH	0x04  /* Match never matches; internal only */
 
 /* Textual representation of the tokens. */
 static struct {
@@ -669,6 +678,7 @@ static struct {
 	{ "trustedusercakeys", sTrustedUserCAKeys, SSHCFG_ALL },
 	{ "authorizedprincipalsfile", sAuthorizedPrincipalsFile, SSHCFG_ALL },
 	{ "kexalgorithms", sKexAlgorithms, SSHCFG_GLOBAL },
+	{ "include", sInclude, SSHCFG_ALL },
 	{ "ipqos", sIPQoS, SSHCFG_ALL },
 	{ "authorizedkeyscommand", sAuthorizedKeysCommand, SSHCFG_ALL },
 	{ "authorizedkeyscommanduser", sAuthorizedKeysCommandUser, SSHCFG_ALL },
@@ -1240,13 +1250,14 @@ static const struct multistate multistate_tcpfwd[] = {
 	{ NULL, -1 }
 };
 
-int
-process_server_config_line(ServerOptions *options, char *line,
+static int
+process_server_config_line_depth(ServerOptions *options, char *line,
     const char *filename, int linenum, int *activep,
-    struct connection_info *connectinfo)
+    struct connection_info *connectinfo, int inc_flags, int depth,
+    struct include_list *includes)
 {
 	char ch, *cp, ***chararrayptr, **charptr, *arg, *arg2, *p;
-	int cmdline = 0, *intptr, value, value2, n, port;
+	int cmdline = 0, *intptr, value, value2, n, port, oactive, r, found;
 	SyslogFacility *log_facility_ptr;
 	LogLevel *log_level_ptr;
 	ServerOpCodes opcode;
@@ -1255,6 +1266,8 @@ process_server_config_line(ServerOptions *options, char *line,
 	long long val64;
 	const struct multistate *multistate_ptr;
 	const char *errstr;
+	struct include_item *item;
+	glob_t gbuf;
 
 	/* Strip trailing whitespace. Allow \f (form feed) at EOL only */
 	if ((len = strlen(line)) == 0)
@@ -1281,7 +1294,7 @@ process_server_config_line(ServerOptions *options, char *line,
 		cmdline = 1;
 		activep = &cmdline;
 	}
-	if (*activep && opcode != sMatch)
+	if (*activep && opcode != sMatch && opcode != sInclude)
 		debug3("%s:%d setting %s %s", filename, linenum, arg, cp);
 	if (*activep == 0 && !(flags & SSHCFG_MATCH)) {
 		if (connectinfo == NULL) {
@@ -1954,6 +1967,96 @@ process_server_config_line(ServerOptions *options, char *line,
 			*intptr = value;
 		break;
 
+	case sInclude:
+		if (cmdline) {
+			fatal("Include directive not supported as a "
+			    "command-line option");
+		}
+		value = 0;
+		while ((arg2 = strdelim(&cp)) != NULL && *arg2 != '\0') {
+			value++;
+			found = 0;
+			if (*arg2 != '/' && *arg2 != '~') {
+				xasprintf(&arg, "%s/%s", SSHDIR, arg);
+			} else
+				arg = xstrdup(arg2);
+
+			/*
+			 * Don't let included files clobber the containing
+			 * file's Match state.
+			 */
+			oactive = *activep;
+
+			/* consult cache of include files */
+			TAILQ_FOREACH(item, includes, entry) {
+				if (strcmp(item->selector, arg) != 0)
+					continue;
+				if (item->filename != NULL) {
+					parse_server_config_depth(options,
+					    item->filename, item->contents,
+					    includes, connectinfo,
+					    (oactive ? 0 : SSHCFG_NEVERMATCH),
+					    activep, depth + 1);
+				}
+				found = 1;
+				*activep = oactive;
+			}
+			if (found != 0) {
+				free(arg);
+				continue;
+			}
+
+			/* requested glob was not in cache */
+			debug2("%s line %d: new include %s",
+			    filename, linenum, arg);
+			if ((r = glob(arg, 0, NULL, &gbuf)) != 0) {
+				if (r != GLOB_NOMATCH) {
+					fatal("%s line %d: include \"%s\" "
+					    "glob failed", filename,
+					    linenum, arg);
+				}
+				/*
+				 * If no entry matched then record a
+				 * placeholder to skip later glob calls.
+				 */
+				debug2("%s line %d: no match for %s",
+				    filename, linenum, arg);
+				item = xcalloc(1, sizeof(*item));
+				item->selector = strdup(arg);
+				TAILQ_INSERT_TAIL(includes,
+				    item, entry);
+			}
+			if (gbuf.gl_pathc > INT_MAX)
+				fatal("%s: too many glob results", __func__);
+			for (n = 0; n < (int)gbuf.gl_pathc; n++) {
+				debug2("%s line %d: including %s",
+				    filename, linenum, gbuf.gl_pathv[n]);
+				item = xcalloc(1, sizeof(*item));
+				item->selector = strdup(arg);
+				item->filename = strdup(gbuf.gl_pathv[n]);
+				if ((item->contents = sshbuf_new()) == NULL) {
+					fatal("%s: sshbuf_new failed",
+					    __func__);
+				}
+				load_server_config(item->filename,
+				    item->contents);
+				parse_server_config_depth(options,
+				    item->filename, item->contents,
+				    includes, connectinfo,
+				    (oactive ? 0 : SSHCFG_NEVERMATCH),
+				    activep, depth + 1);
+				*activep = oactive;
+				TAILQ_INSERT_TAIL(includes, item, entry);
+			}
+			globfree(&gbuf);
+			free(arg);
+		}
+		if (value == 0) {
+			fatal("%s line %d: Include missing filename argument",
+			    filename, linenum);
+		}
+		break;
+
 	case sMatch:
 		if (cmdline)
 			fatal("Match directive not supported as a command-line "
@@ -1962,7 +2065,7 @@ process_server_config_line(ServerOptions *options, char *line,
 		if (value < 0)
 			fatal("%s line %d: Bad Match condition", filename,
 			    linenum);
-		*activep = value;
+		*activep = (inc_flags & SSHCFG_NEVERMATCH) ? 0 : value;
 		break;
 
 	case sPermitListen:
@@ -2256,6 +2359,16 @@ process_server_config_line(ServerOptions *options, char *line,
 	return 0;
 }
 
+int
+process_server_config_line(ServerOptions *options, char *line,
+    const char *filename, int linenum, int *activep,
+    struct connection_info *connectinfo, struct include_list *includes)
+{
+	return process_server_config_line_depth(options, line, filename,
+	    linenum, activep, connectinfo, 0, 0, includes);
+}
+
+
 /* Reads the server configuration file. */
 
 void
@@ -2294,12 +2407,13 @@ load_server_config(const char *filename, struct sshbuf *conf)
 
 void
 parse_server_match_config(ServerOptions *options,
-   struct connection_info *connectinfo)
+   struct include_list *includes, struct connection_info *connectinfo)
 {
 	ServerOptions mo;
 
 	initialize_server_options(&mo);
-	parse_server_config(&mo, "reprocess config", cfg, connectinfo);
+	parse_server_config(&mo, "reprocess config", cfg, includes,
+	    connectinfo);
 	copy_set_server_options(options, &mo, 0);
 }
 
@@ -2443,22 +2557,27 @@ copy_set_server_options(ServerOptions *dst, ServerOptions *src, int preauth)
 #undef M_CP_STROPT
 #undef M_CP_STRARRAYOPT
 
+#define SERVCONF_MAX_DEPTH	16
 void
-parse_server_config(ServerOptions *options, const char *filename,
-    struct sshbuf *conf, struct connection_info *connectinfo)
+parse_server_config_depth(ServerOptions *options, const char *filename,
+    struct sshbuf *conf, struct include_list *includes,
+    struct connection_info *connectinfo, int flags, int *activep, int depth)
 {
-	int active, linenum, bad_options = 0;
+	int linenum, bad_options = 0;
 	char *cp, *obuf, *cbuf;
 
+	if (depth < 0 || depth > SERVCONF_MAX_DEPTH)
+		fatal("Too many recursive configuration includes");
+
 	debug2("%s: config %s len %zu", __func__, filename, sshbuf_len(conf));
 
 	if ((obuf = cbuf = sshbuf_dup_string(conf)) == NULL)
 		fatal("%s: sshbuf_dup_string failed", __func__);
-	active = connectinfo ? 0 : 1;
 	linenum = 1;
 	while ((cp = strsep(&cbuf, "\n")) != NULL) {
-		if (process_server_config_line(options, cp, filename,
-		    linenum++, &active, connectinfo) != 0)
+		if (process_server_config_line_depth(options, cp,
+		    filename, linenum++, activep, connectinfo, flags,
+		    depth, includes) != 0)
 			bad_options++;
 	}
 	free(obuf);
@@ -2468,6 +2587,16 @@ parse_server_config(ServerOptions *options, const char *filename,
 	process_queued_listen_addrs(options);
 }
 
+void
+parse_server_config(ServerOptions *options, const char *filename,
+    struct sshbuf *conf, struct include_list *includes,
+    struct connection_info *connectinfo)
+{
+	int active = connectinfo ? 0 : 1;
+	parse_server_config_depth(options, filename, conf, includes,
+	    connectinfo, 0, &active, 0);
+}
+
 static const char *
 fmt_multistate_int(int val, const struct multistate *m)
 {
diff --git a/servconf.h b/servconf.h
index 6fc1efb2c..deda09d93 100644
--- a/servconf.h
+++ b/servconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.h,v 1.142 2019/12/15 18:57:30 djm Exp $ */
+/* $OpenBSD: servconf.h,v 1.143 2020/01/31 22:42:45 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -16,6 +16,8 @@
 #ifndef SERVCONF_H
 #define SERVCONF_H
 
+#include <sys/queue.h>
+
 #define MAX_PORTS		256	/* Max # ports. */
 
 #define MAX_SUBSYSTEMS		256	/* Max # subsystems. */
@@ -230,6 +232,15 @@ struct connection_info {
 				 * unspecified */
 };
 
+/* List of included files for re-exec from the parsed configuration */
+struct include_item {
+	char *selector;
+	char *filename;
+	struct sshbuf *contents;
+	TAILQ_ENTRY(include_item) entry;
+};
+TAILQ_HEAD(include_list, include_item);
+
 
 /*
  * These are string config options that must be copied between the
@@ -269,12 +280,13 @@ struct connection_info *get_connection_info(struct ssh *, int, int);
 void	 initialize_server_options(ServerOptions *);
 void	 fill_default_server_options(ServerOptions *);
 int	 process_server_config_line(ServerOptions *, char *, const char *, int,
-	     int *, struct connection_info *);
+	     int *, struct connection_info *, struct include_list *includes);
 void	 process_permitopen(struct ssh *ssh, ServerOptions *options);
 void	 load_server_config(const char *, struct sshbuf *);
 void	 parse_server_config(ServerOptions *, const char *, struct sshbuf *,
-	     struct connection_info *);
-void	 parse_server_match_config(ServerOptions *, struct connection_info *);
+	     struct include_list *includes, struct connection_info *);
+void	 parse_server_match_config(ServerOptions *,
+	     struct include_list *includes, struct connection_info *);
 int	 parse_server_match_testspec(struct connection_info *, char *);
 int	 server_match_spec_complete(struct connection_info *);
 void	 copy_set_server_options(ServerOptions *, ServerOptions *, int);
diff --git a/sshd.c b/sshd.c
index 46fdf7ee3..57fab0425 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.545 2020/01/24 23:56:01 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.546 2020/01/31 22:42:45 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -251,6 +251,9 @@ struct sshauthopt *auth_opts = NULL;
 /* sshd_config buffer */
 struct sshbuf *cfg;
 
+/* Included files from the configuration file */
+struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
+
 /* message to be displayed after login */
 struct sshbuf *loginmsg;
 
@@ -870,30 +873,45 @@ usage(void)
 static void
 send_rexec_state(int fd, struct sshbuf *conf)
 {
-	struct sshbuf *m;
+	struct sshbuf *m = NULL, *inc = NULL;
+	struct include_item *item = NULL;
 	int r;
 
 	debug3("%s: entering fd = %d config len %zu", __func__, fd,
 	    sshbuf_len(conf));
 
+	if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+
+	/* pack includes into a string */
+	TAILQ_FOREACH(item, &includes, entry) {
+		if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
+		    (r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
+		    (r = sshbuf_put_stringb(inc, item->contents)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	}
+
 	/*
 	 * Protocol from reexec master to child:
 	 *	string	configuration
-	 *	string rngseed		(only if OpenSSL is not self-seeded)
+	 *	string	included_files[] {
+	 *		string	selector
+	 *		string	filename
+	 *		string	contents
+	 *	}
+	 *	string	rng_seed (if required)
 	 */
-	if ((m = sshbuf_new()) == NULL)
-		fatal("%s: sshbuf_new failed", __func__);
-	if ((r = sshbuf_put_stringb(m, conf)) != 0)
+	if ((r = sshbuf_put_stringb(m, conf)) != 0 ||
+	    (r = sshbuf_put_stringb(m, inc)) != 0)
 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
-
 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
 	rexec_send_rng_seed(m);
 #endif
-
 	if (ssh_msg_send(fd, 0, m) == -1)
 		fatal("%s: ssh_msg_send failed", __func__);
 
 	sshbuf_free(m);
+	sshbuf_free(inc);
 
 	debug3("%s: done", __func__);
 }
@@ -901,14 +919,15 @@ send_rexec_state(int fd, struct sshbuf *conf)
 static void
 recv_rexec_state(int fd, struct sshbuf *conf)
 {
-	struct sshbuf *m;
+	struct sshbuf *m, *inc;
 	u_char *cp, ver;
 	size_t len;
 	int r;
+	struct include_item *item;
 
 	debug3("%s: entering fd = %d", __func__, fd);
 
-	if ((m = sshbuf_new()) == NULL)
+	if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
 		fatal("%s: sshbuf_new failed", __func__);
 	if (ssh_msg_recv(fd, m) == -1)
 		fatal("%s: ssh_msg_recv failed", __func__);
@@ -916,14 +935,28 @@ recv_rexec_state(int fd, struct sshbuf *conf)
 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
 	if (ver != 0)
 		fatal("%s: rexec version mismatch", __func__);
-	if ((r = sshbuf_get_string(m, &cp, &len)) != 0)
-		fatal("%s: buffer error: %s", __func__, ssh_err(r));
-	if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
+	if ((r = sshbuf_get_string(m, &cp, &len)) != 0 ||
+	    (r = sshbuf_get_stringb(m, inc)) != 0)
 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
 	rexec_recv_rng_seed(m);
 #endif
 
+	if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	while (sshbuf_len(inc) != 0) {
+		item = xcalloc(1, sizeof(*item));
+		if ((item->contents = sshbuf_new()) == NULL)
+			fatal("%s: sshbuf_new failed", __func__);
+		if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
+		    (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
+		    (r = sshbuf_get_stringb(inc, item->contents)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+		TAILQ_INSERT_TAIL(&includes, item, entry);
+	}
+
 	free(cp);
 	sshbuf_free(m);
 
@@ -1600,7 +1633,7 @@ main(int ac, char **av)
 		case 'o':
 			line = xstrdup(optarg);
 			if (process_server_config_line(&options, line,
-			    "command-line", 0, NULL, NULL) != 0)
+			    "command-line", 0, NULL, NULL, &includes) != 0)
 				exit(1);
 			free(line);
 			break;
@@ -1669,7 +1702,7 @@ main(int ac, char **av)
 		load_server_config(config_file_name, cfg);
 
 	parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
-	    cfg, NULL);
+	    cfg, &includes, NULL);
 
 	/* Fill in default values for those options not explicitly set. */
 	fill_default_server_options(&options);
@@ -1895,7 +1928,7 @@ main(int ac, char **av)
 		if (connection_info == NULL)
 			connection_info = get_connection_info(ssh, 0, 0);
 		connection_info->test = 1;
-		parse_server_match_config(&options, connection_info);
+		parse_server_match_config(&options, &includes, connection_info);
 		dump_config(&options);
 	}
 
diff --git a/sshd_config.5 b/sshd_config.5
index 1395a5e6d..6c3b5e5e0 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.303 2020/01/28 01:49:36 djm Exp $
-.Dd $Mdocdate: January 28 2020 $
+.\" $OpenBSD: sshd_config.5,v 1.304 2020/01/31 22:42:45 djm Exp $
+.Dd $Mdocdate: January 31 2020 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -801,7 +801,20 @@ during
 and use only the system-wide known hosts file
 .Pa /etc/ssh/known_hosts .
 The default is
-.Cm no .
+.Dq no .
+.It Cm Include
+Include the specified configuration file(s).
+Multiple path names may be specified and each pathname may contain
+.Xr glob 7
+wildcards.
+Files without absolute paths are assumed to be in
+.Pa /etc/ssh .
+A
+.Cm Include
+directive may appear inside a
+.Cm Match
+block
+to perform conditional inclusion.
 .It Cm IPQoS
 Specifies the IPv4 type-of-service or DSCP class for the connection.
 Accepted values are
-- 
cgit v1.2.3


From 34aff3aa136e5a65f441b25811dd466488fda087 Mon Sep 17 00:00:00 2001
From: Simon Wilkinson <simon@sxw.org.uk>
Date: Sun, 9 Feb 2014 16:09:48 +0000
Subject: GSSAPI key exchange support

This patch has been rejected upstream: "None of the OpenSSH developers are
in favour of adding this, and this situation has not changed for several
years.  This is not a slight on Simon's patch, which is of fine quality, but
just that a) we don't trust GSSAPI implementations that much and b) we don't
like adding new KEX since they are pre-auth attack surface.  This one is
particularly scary, since it requires hooks out to typically root-owned
system resources."

However, quite a lot of people rely on this in Debian, and it's better to
have it merged into the main openssh package rather than having separate
-krb5 packages (as we used to have).  It seems to have a generally good
security history.

Origin: other, https://github.com/openssh-gsskex/openssh-gsskex/commits/debian/master
Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1242
Last-Updated: 2020-02-21

Patch-Name: gssapi.patch
---
 Makefile.in     |   3 +-
 README.md       |  33 +++
 auth.c          |  96 +--------
 auth2-gss.c     |  56 +++++-
 auth2.c         |   2 +
 canohost.c      |  93 +++++++++
 canohost.h      |   3 +
 clientloop.c    |  15 +-
 configure.ac    |  24 +++
 gss-genr.c      | 300 +++++++++++++++++++++++++++-
 gss-serv-krb5.c |  85 +++++++-
 gss-serv.c      | 186 +++++++++++++++--
 kex.c           |  66 +++++-
 kex.h           |  29 +++
 kexdh.c         |  10 +
 kexgen.c        |   2 +-
 kexgssc.c       | 606 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 kexgsss.c       | 474 ++++++++++++++++++++++++++++++++++++++++++++
 monitor.c       | 139 ++++++++++++-
 monitor.h       |   2 +
 monitor_wrap.c  |  57 +++++-
 monitor_wrap.h  |   4 +-
 readconf.c      |  70 +++++++
 readconf.h      |   6 +
 servconf.c      |  47 +++++
 servconf.h      |   3 +
 session.c       |  10 +-
 ssh-gss.h       |  50 ++++-
 ssh.1           |   8 +
 ssh.c           |   6 +-
 ssh_config      |   2 +
 ssh_config.5    |  57 ++++++
 sshconnect2.c   | 142 ++++++++++++-
 sshd.c          |  62 +++++-
 sshd_config     |   2 +
 sshd_config.5   |  30 +++
 sshkey.c        |   3 +-
 sshkey.h        |   1 +
 38 files changed, 2624 insertions(+), 160 deletions(-)
 create mode 100644 kexgssc.c
 create mode 100644 kexgsss.c

(limited to 'auth.c')

diff --git a/Makefile.in b/Makefile.in
index e7549470c..b68c1710f 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -109,6 +109,7 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \
 	kex.o kexdh.o kexgex.o kexecdh.o kexc25519.o \
 	kexgexc.o kexgexs.o \
 	sntrup4591761.o kexsntrup4591761x25519.o kexgen.o \
+	kexgssc.o \
 	sftp-realpath.o platform-pledge.o platform-tracing.o platform-misc.o \
 	sshbuf-io.o
 
@@ -125,7 +126,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o \
 	auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \
 	auth2-none.o auth2-passwd.o auth2-pubkey.o \
 	monitor.o monitor_wrap.o auth-krb5.o \
-	auth2-gss.o gss-serv.o gss-serv-krb5.o \
+	auth2-gss.o gss-serv.o gss-serv-krb5.o kexgsss.o \
 	loginrec.o auth-pam.o auth-shadow.o auth-sia.o md5crypt.o \
 	sftp-server.o sftp-common.o \
 	sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \
diff --git a/README.md b/README.md
index 28fb43d2a..5b73d24c0 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,36 @@
+Portable OpenSSH with GSSAPI Key Exchange patches
+=================================================
+
+Currently, there are two branches with gssapi key exchange related
+patches:
+
+ * fedora/master: Changes that are shipped in Fedora
+ * debian/master: Changes that are shipped in Debian
+
+The target is to converge to a shared repository with single master
+branch from where we could build releases for both OSes.
+
+
+What is in:
+
+ * The original patch implementing missing parts of RFC4462 by Simon Wilkinson
+   adapted to the current OpenSSH versions and with several fixes
+ * New methods for GSSAPI Kex from IETF draft [1] from Jakub Jelen
+
+
+Missing kerberos-related parts:
+
+ * .k5login and .kusers support available in Fedora [2] [3].
+ * Improved handling of kerberos ccache location [4]
+
+
+[1] https://tools.ietf.org/html/draft-ietf-curdle-gss-keyex-sha2-08
+[2] https://src.fedoraproject.org/rpms/openssh/blob/master/f/openssh-6.6p1-kuserok.patch
+[3] https://src.fedoraproject.org/rpms/openssh/blob/master/f/openssh-6.6p1-GSSAPIEnablek5users.patch
+[4] https://bugzilla.mindrot.org/show_bug.cgi?id=2775
+
+-------------------------------------------------------------------------------
+
 # Portable OpenSSH
 
 [![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/openssh.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:openssh)
diff --git a/auth.c b/auth.c
index 086b8ebb1..687c57b42 100644
--- a/auth.c
+++ b/auth.c
@@ -400,7 +400,8 @@ auth_root_allowed(struct ssh *ssh, const char *method)
 	case PERMIT_NO_PASSWD:
 		if (strcmp(method, "publickey") == 0 ||
 		    strcmp(method, "hostbased") == 0 ||
-		    strcmp(method, "gssapi-with-mic") == 0)
+		    strcmp(method, "gssapi-with-mic") == 0 ||
+		    strcmp(method, "gssapi-keyex") == 0)
 			return 1;
 		break;
 	case PERMIT_FORCED_ONLY:
@@ -724,99 +725,6 @@ fakepw(void)
 	return (&fake);
 }
 
-/*
- * Returns the remote DNS hostname as a string. The returned string must not
- * be freed. NB. this will usually trigger a DNS query the first time it is
- * called.
- * This function does additional checks on the hostname to mitigate some
- * attacks on legacy rhosts-style authentication.
- * XXX is RhostsRSAAuthentication vulnerable to these?
- * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
- */
-
-static char *
-remote_hostname(struct ssh *ssh)
-{
-	struct sockaddr_storage from;
-	socklen_t fromlen;
-	struct addrinfo hints, *ai, *aitop;
-	char name[NI_MAXHOST], ntop2[NI_MAXHOST];
-	const char *ntop = ssh_remote_ipaddr(ssh);
-
-	/* Get IP address of client. */
-	fromlen = sizeof(from);
-	memset(&from, 0, sizeof(from));
-	if (getpeername(ssh_packet_get_connection_in(ssh),
-	    (struct sockaddr *)&from, &fromlen) == -1) {
-		debug("getpeername failed: %.100s", strerror(errno));
-		return xstrdup(ntop);
-	}
-
-	ipv64_normalise_mapped(&from, &fromlen);
-	if (from.ss_family == AF_INET6)
-		fromlen = sizeof(struct sockaddr_in6);
-
-	debug3("Trying to reverse map address %.100s.", ntop);
-	/* Map the IP address to a host name. */
-	if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
-	    NULL, 0, NI_NAMEREQD) != 0) {
-		/* Host name not found.  Use ip address. */
-		return xstrdup(ntop);
-	}
-
-	/*
-	 * if reverse lookup result looks like a numeric hostname,
-	 * someone is trying to trick us by PTR record like following:
-	 *	1.1.1.10.in-addr.arpa.	IN PTR	2.3.4.5
-	 */
-	memset(&hints, 0, sizeof(hints));
-	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
-	hints.ai_flags = AI_NUMERICHOST;
-	if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
-		logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
-		    name, ntop);
-		freeaddrinfo(ai);
-		return xstrdup(ntop);
-	}
-
-	/* Names are stored in lowercase. */
-	lowercase(name);
-
-	/*
-	 * Map it back to an IP address and check that the given
-	 * address actually is an address of this host.  This is
-	 * necessary because anyone with access to a name server can
-	 * define arbitrary names for an IP address. Mapping from
-	 * name to IP address can be trusted better (but can still be
-	 * fooled if the intruder has access to the name server of
-	 * the domain).
-	 */
-	memset(&hints, 0, sizeof(hints));
-	hints.ai_family = from.ss_family;
-	hints.ai_socktype = SOCK_STREAM;
-	if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
-		logit("reverse mapping checking getaddrinfo for %.700s "
-		    "[%s] failed.", name, ntop);
-		return xstrdup(ntop);
-	}
-	/* Look for the address from the list of addresses. */
-	for (ai = aitop; ai; ai = ai->ai_next) {
-		if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
-		    sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
-		    (strcmp(ntop, ntop2) == 0))
-				break;
-	}
-	freeaddrinfo(aitop);
-	/* If we reached the end of the list, the address was not there. */
-	if (ai == NULL) {
-		/* Address not found for the host name. */
-		logit("Address %.100s maps to %.600s, but this does not "
-		    "map back to the address.", ntop, name);
-		return xstrdup(ntop);
-	}
-	return xstrdup(name);
-}
-
 /*
  * Return the canonical name of the host in the other side of the current
  * connection.  The host name is cached, so it is efficient to call this
diff --git a/auth2-gss.c b/auth2-gss.c
index 9351e0428..d6446c0cf 100644
--- a/auth2-gss.c
+++ b/auth2-gss.c
@@ -1,7 +1,7 @@
 /* $OpenBSD: auth2-gss.c,v 1.29 2018/07/31 03:10:27 djm Exp $ */
 
 /*
- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -54,6 +54,48 @@ static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh);
 static int input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh);
 static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
 
+/*
+ * The 'gssapi_keyex' userauth mechanism.
+ */
+static int
+userauth_gsskeyex(struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	int r, authenticated = 0;
+	struct sshbuf *b = NULL;
+	gss_buffer_desc mic, gssbuf;
+	u_char *p;
+	size_t len;
+
+	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+
+	mic.value = p;
+	mic.length = len;
+
+	ssh_gssapi_buildmic(b, authctxt->user, authctxt->service,
+	    "gssapi-keyex");
+
+	if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
+		fatal("%s: sshbuf_mutable_ptr failed", __func__);
+	gssbuf.length = sshbuf_len(b);
+
+	/* gss_kex_context is NULL with privsep, so we can't check it here */
+	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
+	    &gssbuf, &mic))))
+		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
+		    authctxt->pw, 1));
+
+	sshbuf_free(b);
+	free(mic.value);
+
+	return (authenticated);
+}
+
 /*
  * We only support those mechanisms that we know about (ie ones that we know
  * how to check local user kuserok and the like)
@@ -260,7 +302,8 @@ input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh)
 	if ((r = sshpkt_get_end(ssh)) != 0)
 		fatal("%s: %s", __func__, ssh_err(r));
 
-	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
+	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
+	    authctxt->pw, 1));
 
 	if ((!use_privsep || mm_is_monitor()) &&
 	    (displayname = ssh_gssapi_displayname()) != NULL)
@@ -306,7 +349,8 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh)
 	gssbuf.length = sshbuf_len(b);
 
 	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
-		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
+		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
+		    authctxt->pw, 0));
 	else
 		logit("GSSAPI MIC check failed");
 
@@ -326,6 +370,12 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh)
 	return 0;
 }
 
+Authmethod method_gsskeyex = {
+	"gssapi-keyex",
+	userauth_gsskeyex,
+	&options.gss_authentication
+};
+
 Authmethod method_gssapi = {
 	"gssapi-with-mic",
 	userauth_gssapi,
diff --git a/auth2.c b/auth2.c
index 0e7762242..1c217268c 100644
--- a/auth2.c
+++ b/auth2.c
@@ -73,6 +73,7 @@ extern Authmethod method_passwd;
 extern Authmethod method_kbdint;
 extern Authmethod method_hostbased;
 #ifdef GSSAPI
+extern Authmethod method_gsskeyex;
 extern Authmethod method_gssapi;
 #endif
 
@@ -80,6 +81,7 @@ Authmethod *authmethods[] = {
 	&method_none,
 	&method_pubkey,
 #ifdef GSSAPI
+	&method_gsskeyex,
 	&method_gssapi,
 #endif
 	&method_passwd,
diff --git a/canohost.c b/canohost.c
index abea9c6e6..8e81b5193 100644
--- a/canohost.c
+++ b/canohost.c
@@ -35,6 +35,99 @@
 #include "canohost.h"
 #include "misc.h"
 
+/*
+ * Returns the remote DNS hostname as a string. The returned string must not
+ * be freed. NB. this will usually trigger a DNS query the first time it is
+ * called.
+ * This function does additional checks on the hostname to mitigate some
+ * attacks on legacy rhosts-style authentication.
+ * XXX is RhostsRSAAuthentication vulnerable to these?
+ * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
+ */
+
+char *
+remote_hostname(struct ssh *ssh)
+{
+	struct sockaddr_storage from;
+	socklen_t fromlen;
+	struct addrinfo hints, *ai, *aitop;
+	char name[NI_MAXHOST], ntop2[NI_MAXHOST];
+	const char *ntop = ssh_remote_ipaddr(ssh);
+
+	/* Get IP address of client. */
+	fromlen = sizeof(from);
+	memset(&from, 0, sizeof(from));
+	if (getpeername(ssh_packet_get_connection_in(ssh),
+	    (struct sockaddr *)&from, &fromlen) == -1) {
+		debug("getpeername failed: %.100s", strerror(errno));
+		return xstrdup(ntop);
+	}
+
+	ipv64_normalise_mapped(&from, &fromlen);
+	if (from.ss_family == AF_INET6)
+		fromlen = sizeof(struct sockaddr_in6);
+
+	debug3("Trying to reverse map address %.100s.", ntop);
+	/* Map the IP address to a host name. */
+	if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
+	    NULL, 0, NI_NAMEREQD) != 0) {
+		/* Host name not found.  Use ip address. */
+		return xstrdup(ntop);
+	}
+
+	/*
+	 * if reverse lookup result looks like a numeric hostname,
+	 * someone is trying to trick us by PTR record like following:
+	 *	1.1.1.10.in-addr.arpa.	IN PTR	2.3.4.5
+	 */
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
+	hints.ai_flags = AI_NUMERICHOST;
+	if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
+		logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
+		    name, ntop);
+		freeaddrinfo(ai);
+		return xstrdup(ntop);
+	}
+
+	/* Names are stored in lowercase. */
+	lowercase(name);
+
+	/*
+	 * Map it back to an IP address and check that the given
+	 * address actually is an address of this host.  This is
+	 * necessary because anyone with access to a name server can
+	 * define arbitrary names for an IP address. Mapping from
+	 * name to IP address can be trusted better (but can still be
+	 * fooled if the intruder has access to the name server of
+	 * the domain).
+	 */
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = from.ss_family;
+	hints.ai_socktype = SOCK_STREAM;
+	if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
+		logit("reverse mapping checking getaddrinfo for %.700s "
+		    "[%s] failed.", name, ntop);
+		return xstrdup(ntop);
+	}
+	/* Look for the address from the list of addresses. */
+	for (ai = aitop; ai; ai = ai->ai_next) {
+		if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
+		    sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
+		    (strcmp(ntop, ntop2) == 0))
+				break;
+	}
+	freeaddrinfo(aitop);
+	/* If we reached the end of the list, the address was not there. */
+	if (ai == NULL) {
+		/* Address not found for the host name. */
+		logit("Address %.100s maps to %.600s, but this does not "
+		    "map back to the address.", ntop, name);
+		return xstrdup(ntop);
+	}
+	return xstrdup(name);
+}
+
 void
 ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
 {
diff --git a/canohost.h b/canohost.h
index 26d62855a..0cadc9f18 100644
--- a/canohost.h
+++ b/canohost.h
@@ -15,6 +15,9 @@
 #ifndef _CANOHOST_H
 #define _CANOHOST_H
 
+struct ssh;
+
+char		*remote_hostname(struct ssh *);
 char		*get_peer_ipaddr(int);
 int		 get_peer_port(int);
 char		*get_local_ipaddr(int);
diff --git a/clientloop.c b/clientloop.c
index ebd0dbca1..1bdac6a46 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -112,6 +112,10 @@
 #include "ssherr.h"
 #include "hostfile.h"
 
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+
 /* import options */
 extern Options options;
 
@@ -1379,9 +1383,18 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
 			break;
 
 		/* Do channel operations unless rekeying in progress. */
-		if (!ssh_packet_is_rekeying(ssh))
+		if (!ssh_packet_is_rekeying(ssh)) {
 			channel_after_select(ssh, readset, writeset);
 
+#ifdef GSSAPI
+			if (options.gss_renewal_rekey &&
+			    ssh_gssapi_credentials_updated(NULL)) {
+				debug("credentials updated - forcing rekey");
+				need_rekeying = 1;
+			}
+#endif
+		}
+
 		/* Buffer input from the connection.  */
 		client_process_net_input(ssh, readset);
 
diff --git a/configure.ac b/configure.ac
index b689db4b5..efafb6bd8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -674,6 +674,30 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16))
 	    [Use tunnel device compatibility to OpenBSD])
 	AC_DEFINE([SSH_TUN_PREPEND_AF], [1],
 	    [Prepend the address family to IP tunnel traffic])
+	AC_MSG_CHECKING([if we have the Security Authorization Session API])
+	AC_TRY_COMPILE([#include <Security/AuthSession.h>],
+		[SessionCreate(0, 0);],
+		[ac_cv_use_security_session_api="yes"
+		 AC_DEFINE([USE_SECURITY_SESSION_API], [1],
+			[platform has the Security Authorization Session API])
+		 LIBS="$LIBS -framework Security"
+		 AC_MSG_RESULT([yes])],
+		[ac_cv_use_security_session_api="no"
+		 AC_MSG_RESULT([no])])
+	AC_MSG_CHECKING([if we have an in-memory credentials cache])
+	AC_TRY_COMPILE(
+		[#include <Kerberos/Kerberos.h>],
+		[cc_context_t c;
+		 (void) cc_initialize (&c, 0, NULL, NULL);],
+		[AC_DEFINE([USE_CCAPI], [1],
+			[platform uses an in-memory credentials cache])
+		 LIBS="$LIBS -framework Security"
+		 AC_MSG_RESULT([yes])
+		 if test "x$ac_cv_use_security_session_api" = "xno"; then
+			AC_MSG_ERROR([*** Need a security framework to use the credentials cache API ***])
+		fi],
+		[AC_MSG_RESULT([no])]
+	)
 	m4_pattern_allow([AU_IPv])
 	AC_CHECK_DECL([AU_IPv4], [],
 	    AC_DEFINE([AU_IPv4], [0], [System only supports IPv4 audit records])
diff --git a/gss-genr.c b/gss-genr.c
index d56257b4a..763a63ffa 100644
--- a/gss-genr.c
+++ b/gss-genr.c
@@ -1,7 +1,7 @@
 /* $OpenBSD: gss-genr.c,v 1.26 2018/07/10 09:13:30 djm Exp $ */
 
 /*
- * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -41,12 +41,36 @@
 #include "sshbuf.h"
 #include "log.h"
 #include "ssh2.h"
+#include "cipher.h"
+#include "sshkey.h"
+#include "kex.h"
+#include "digest.h"
+#include "packet.h"
 
 #include "ssh-gss.h"
 
 extern u_char *session_id2;
 extern u_int session_id2_len;
 
+typedef struct {
+	char *encoded;
+	gss_OID oid;
+} ssh_gss_kex_mapping;
+
+/*
+ * XXX - It would be nice to find a more elegant way of handling the
+ * XXX   passing of the key exchange context to the userauth routines
+ */
+
+Gssctxt *gss_kex_context = NULL;
+
+static ssh_gss_kex_mapping *gss_enc2oid = NULL;
+
+int
+ssh_gssapi_oid_table_ok(void) {
+	return (gss_enc2oid != NULL);
+}
+
 /* sshbuf_get for gss_buffer_desc */
 int
 ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
@@ -62,6 +86,162 @@ ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
 	return 0;
 }
 
+/* sshpkt_get of gss_buffer_desc */
+int
+ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *ssh, gss_buffer_desc *g)
+{
+	int r;
+	u_char *p;
+	size_t len;
+
+	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0)
+		return r;
+	g->value = p;
+	g->length = len;
+	return 0;
+}
+
+/*
+ * Return a list of the gss-group1-sha1 mechanisms supported by this program
+ *
+ * We test mechanisms to ensure that we can use them, to avoid starting
+ * a key exchange with a bad mechanism
+ */
+
+char *
+ssh_gssapi_client_mechanisms(const char *host, const char *client,
+    const char *kex) {
+	gss_OID_set gss_supported = NULL;
+	OM_uint32 min_status;
+
+	if (GSS_ERROR(gss_indicate_mechs(&min_status, &gss_supported)))
+		return NULL;
+
+	return ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism,
+	    host, client, kex);
+}
+
+char *
+ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check,
+    const char *host, const char *client, const char *kex) {
+	struct sshbuf *buf = NULL;
+	size_t i;
+	int r = SSH_ERR_ALLOC_FAIL;
+	int oidpos, enclen;
+	char *mechs, *encoded;
+	u_char digest[SSH_DIGEST_MAX_LENGTH];
+	char deroid[2];
+	struct ssh_digest_ctx *md = NULL;
+	char *s, *cp, *p;
+
+	if (gss_enc2oid != NULL) {
+		for (i = 0; gss_enc2oid[i].encoded != NULL; i++)
+			free(gss_enc2oid[i].encoded);
+		free(gss_enc2oid);
+	}
+
+	gss_enc2oid = xmalloc(sizeof(ssh_gss_kex_mapping) *
+	    (gss_supported->count + 1));
+
+	if ((buf = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+
+	oidpos = 0;
+	s = cp = xstrdup(kex);
+	for (i = 0; i < gss_supported->count; i++) {
+		if (gss_supported->elements[i].length < 128 &&
+		    (*check)(NULL, &(gss_supported->elements[i]), host, client)) {
+
+			deroid[0] = SSH_GSS_OIDTYPE;
+			deroid[1] = gss_supported->elements[i].length;
+
+			if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
+			    (r = ssh_digest_update(md, deroid, 2)) != 0 ||
+			    (r = ssh_digest_update(md,
+			        gss_supported->elements[i].elements,
+			        gss_supported->elements[i].length)) != 0 ||
+			    (r = ssh_digest_final(md, digest, sizeof(digest))) != 0)
+				fatal("%s: digest failed: %s", __func__,
+				    ssh_err(r));
+			ssh_digest_free(md);
+			md = NULL;
+
+			encoded = xmalloc(ssh_digest_bytes(SSH_DIGEST_MD5)
+			    * 2);
+			enclen = __b64_ntop(digest,
+			    ssh_digest_bytes(SSH_DIGEST_MD5), encoded,
+			    ssh_digest_bytes(SSH_DIGEST_MD5) * 2);
+
+			cp = strncpy(s, kex, strlen(kex));
+			for ((p = strsep(&cp, ",")); p && *p != '\0';
+				(p = strsep(&cp, ","))) {
+				if (sshbuf_len(buf) != 0 &&
+				    (r = sshbuf_put_u8(buf, ',')) != 0)
+					fatal("%s: sshbuf_put_u8 error: %s",
+					    __func__, ssh_err(r));
+				if ((r = sshbuf_put(buf, p, strlen(p))) != 0 ||
+				    (r = sshbuf_put(buf, encoded, enclen)) != 0)
+					fatal("%s: sshbuf_put error: %s",
+					    __func__, ssh_err(r));
+			}
+
+			gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]);
+			gss_enc2oid[oidpos].encoded = encoded;
+			oidpos++;
+		}
+	}
+	free(s);
+	gss_enc2oid[oidpos].oid = NULL;
+	gss_enc2oid[oidpos].encoded = NULL;
+
+	if ((mechs = sshbuf_dup_string(buf)) == NULL)
+		fatal("%s: sshbuf_dup_string failed", __func__);
+
+	sshbuf_free(buf);
+
+	if (strlen(mechs) == 0) {
+		free(mechs);
+		mechs = NULL;
+	}
+
+	return (mechs);
+}
+
+gss_OID
+ssh_gssapi_id_kex(Gssctxt *ctx, char *name, int kex_type) {
+	int i = 0;
+
+#define SKIP_KEX_NAME(type) \
+	case type: \
+		if (strlen(name) < sizeof(type##_ID)) \
+			return GSS_C_NO_OID; \
+		name += sizeof(type##_ID) - 1; \
+		break;
+
+	switch (kex_type) {
+	SKIP_KEX_NAME(KEX_GSS_GRP1_SHA1)
+	SKIP_KEX_NAME(KEX_GSS_GRP14_SHA1)
+	SKIP_KEX_NAME(KEX_GSS_GRP14_SHA256)
+	SKIP_KEX_NAME(KEX_GSS_GRP16_SHA512)
+	SKIP_KEX_NAME(KEX_GSS_GEX_SHA1)
+	SKIP_KEX_NAME(KEX_GSS_NISTP256_SHA256)
+	SKIP_KEX_NAME(KEX_GSS_C25519_SHA256)
+	default:
+		return GSS_C_NO_OID;
+	}
+
+#undef SKIP_KEX_NAME
+
+	while (gss_enc2oid[i].encoded != NULL &&
+	    strcmp(name, gss_enc2oid[i].encoded) != 0)
+		i++;
+
+	if (gss_enc2oid[i].oid != NULL && ctx != NULL)
+		ssh_gssapi_set_oid(ctx, gss_enc2oid[i].oid);
+
+	return gss_enc2oid[i].oid;
+}
+
 /* Check that the OID in a data stream matches that in the context */
 int
 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
@@ -218,7 +398,7 @@ ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
 	}
 
 	ctx->major = gss_init_sec_context(&ctx->minor,
-	    GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
+	    ctx->client_creds, &ctx->context, ctx->name, ctx->oid,
 	    GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
 	    0, NULL, recv_tok, NULL, send_tok, flags, NULL);
 
@@ -247,9 +427,43 @@ ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
 	return (ctx->major);
 }
 
+OM_uint32
+ssh_gssapi_client_identity(Gssctxt *ctx, const char *name)
+{
+	gss_buffer_desc gssbuf;
+	gss_name_t gssname;
+	OM_uint32 status;
+	gss_OID_set oidset;
+
+	gssbuf.value = (void *) name;
+	gssbuf.length = strlen(gssbuf.value);
+
+	gss_create_empty_oid_set(&status, &oidset);
+	gss_add_oid_set_member(&status, ctx->oid, &oidset);
+
+	ctx->major = gss_import_name(&ctx->minor, &gssbuf,
+	    GSS_C_NT_USER_NAME, &gssname);
+
+	if (!ctx->major)
+		ctx->major = gss_acquire_cred(&ctx->minor,
+		    gssname, 0, oidset, GSS_C_INITIATE,
+		    &ctx->client_creds, NULL, NULL);
+
+	gss_release_name(&status, &gssname);
+	gss_release_oid_set(&status, &oidset);
+
+	if (ctx->major)
+		ssh_gssapi_error(ctx);
+
+	return(ctx->major);
+}
+
 OM_uint32
 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
 {
+	if (ctx == NULL)
+		return -1;
+
 	if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
 	    GSS_C_QOP_DEFAULT, buffer, hash)))
 		ssh_gssapi_error(ctx);
@@ -257,6 +471,19 @@ ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
 	return (ctx->major);
 }
 
+/* Priviledged when used by server */
+OM_uint32
+ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
+{
+	if (ctx == NULL)
+		return -1;
+
+	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
+	    gssbuf, gssmic, NULL);
+
+	return (ctx->major);
+}
+
 void
 ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
     const char *context)
@@ -273,11 +500,16 @@ ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
 }
 
 int
-ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
+ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host,
+    const char *client)
 {
 	gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
 	OM_uint32 major, minor;
 	gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
+	Gssctxt *intctx = NULL;
+
+	if (ctx == NULL)
+		ctx = &intctx;
 
 	/* RFC 4462 says we MUST NOT do SPNEGO */
 	if (oid->length == spnego_oid.length && 
@@ -287,6 +519,10 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
 	ssh_gssapi_build_ctx(ctx);
 	ssh_gssapi_set_oid(*ctx, oid);
 	major = ssh_gssapi_import_name(*ctx, host);
+
+	if (!GSS_ERROR(major) && client)
+		major = ssh_gssapi_client_identity(*ctx, client);
+
 	if (!GSS_ERROR(major)) {
 		major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, 
 		    NULL);
@@ -296,10 +532,66 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
 			    GSS_C_NO_BUFFER);
 	}
 
-	if (GSS_ERROR(major)) 
+	if (GSS_ERROR(major) || intctx != NULL)
 		ssh_gssapi_delete_ctx(ctx);
 
 	return (!GSS_ERROR(major));
 }
 
+int
+ssh_gssapi_credentials_updated(Gssctxt *ctxt) {
+	static gss_name_t saved_name = GSS_C_NO_NAME;
+	static OM_uint32 saved_lifetime = 0;
+	static gss_OID saved_mech = GSS_C_NO_OID;
+	static gss_name_t name;
+	static OM_uint32 last_call = 0;
+	OM_uint32 lifetime, now, major, minor;
+	int equal;
+
+	now = time(NULL);
+
+	if (ctxt) {
+		debug("Rekey has happened - updating saved versions");
+
+		if (saved_name != GSS_C_NO_NAME)
+			gss_release_name(&minor, &saved_name);
+
+		major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL,
+		    &saved_name, &saved_lifetime, NULL, NULL);
+
+		if (!GSS_ERROR(major)) {
+			saved_mech = ctxt->oid;
+		        saved_lifetime+= now;
+		} else {
+			/* Handle the error */
+		}
+		return 0;
+	}
+
+	if (now - last_call < 10)
+		return 0;
+
+	last_call = now;
+
+	if (saved_mech == GSS_C_NO_OID)
+		return 0;
+
+	major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL,
+	    &name, &lifetime, NULL, NULL);
+	if (major == GSS_S_CREDENTIALS_EXPIRED)
+		return 0;
+	else if (GSS_ERROR(major))
+		return 0;
+
+	major = gss_compare_name(&minor, saved_name, name, &equal);
+	gss_release_name(&minor, &name);
+	if (GSS_ERROR(major))
+		return 0;
+
+	if (equal && (saved_lifetime < lifetime + now - 10))
+		return 1;
+
+	return 0;
+}
+
 #endif /* GSSAPI */
diff --git a/gss-serv-krb5.c b/gss-serv-krb5.c
index a151bc1e4..ef9beb67c 100644
--- a/gss-serv-krb5.c
+++ b/gss-serv-krb5.c
@@ -1,7 +1,7 @@
 /* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus Exp $ */
 
 /*
- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -120,8 +120,8 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 	krb5_error_code problem;
 	krb5_principal princ;
 	OM_uint32 maj_status, min_status;
-	int len;
 	const char *errmsg;
+	const char *new_ccname;
 
 	if (client->creds == NULL) {
 		debug("No credentials stored");
@@ -180,11 +180,16 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 		return;
 	}
 
-	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
+	new_ccname = krb5_cc_get_name(krb_context, ccache);
+
 	client->store.envvar = "KRB5CCNAME";
-	len = strlen(client->store.filename) + 6;
-	client->store.envval = xmalloc(len);
-	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
+#ifdef USE_CCAPI
+	xasprintf(&client->store.envval, "API:%s", new_ccname);
+	client->store.filename = NULL;
+#else
+	xasprintf(&client->store.envval, "FILE:%s", new_ccname);
+	client->store.filename = xstrdup(new_ccname);
+#endif
 
 #ifdef USE_PAM
 	if (options.use_pam)
@@ -196,6 +201,71 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 	return;
 }
 
+int
+ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store,
+    ssh_gssapi_client *client)
+{
+	krb5_ccache ccache = NULL;
+	krb5_principal principal = NULL;
+	char *name = NULL;
+	krb5_error_code problem;
+	OM_uint32 maj_status, min_status;
+
+	if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) {
+                logit("krb5_cc_resolve(): %.100s",
+                    krb5_get_err_text(krb_context, problem));
+                return 0;
+	}
+
+	/* Find out who the principal in this cache is */
+	if ((problem = krb5_cc_get_principal(krb_context, ccache,
+	    &principal))) {
+		logit("krb5_cc_get_principal(): %.100s",
+		    krb5_get_err_text(krb_context, problem));
+		krb5_cc_close(krb_context, ccache);
+		return 0;
+	}
+
+	if ((problem = krb5_unparse_name(krb_context, principal, &name))) {
+		logit("krb5_unparse_name(): %.100s",
+		    krb5_get_err_text(krb_context, problem));
+		krb5_free_principal(krb_context, principal);
+		krb5_cc_close(krb_context, ccache);
+		return 0;
+	}
+
+
+	if (strcmp(name,client->exportedname.value)!=0) {
+		debug("Name in local credentials cache differs. Not storing");
+		krb5_free_principal(krb_context, principal);
+		krb5_cc_close(krb_context, ccache);
+		krb5_free_unparsed_name(krb_context, name);
+		return 0;
+	}
+	krb5_free_unparsed_name(krb_context, name);
+
+	/* Name matches, so lets get on with it! */
+
+	if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) {
+		logit("krb5_cc_initialize(): %.100s",
+		    krb5_get_err_text(krb_context, problem));
+		krb5_free_principal(krb_context, principal);
+		krb5_cc_close(krb_context, ccache);
+		return 0;
+	}
+
+	krb5_free_principal(krb_context, principal);
+
+	if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds,
+	    ccache))) {
+		logit("gss_krb5_copy_ccache() failed. Sorry!");
+		krb5_cc_close(krb_context, ccache);
+		return 0;
+	}
+
+	return 1;
+}
+
 ssh_gssapi_mech gssapi_kerberos_mech = {
 	"toWM5Slw5Ew8Mqkay+al2g==",
 	"Kerberos",
@@ -203,7 +273,8 @@ ssh_gssapi_mech gssapi_kerberos_mech = {
 	NULL,
 	&ssh_gssapi_krb5_userok,
 	NULL,
-	&ssh_gssapi_krb5_storecreds
+	&ssh_gssapi_krb5_storecreds,
+	&ssh_gssapi_krb5_updatecreds
 };
 
 #endif /* KRB5 */
diff --git a/gss-serv.c b/gss-serv.c
index ab3a15f0f..1d47870e7 100644
--- a/gss-serv.c
+++ b/gss-serv.c
@@ -1,7 +1,7 @@
 /* $OpenBSD: gss-serv.c,v 1.31 2018/07/09 21:37:55 markus Exp $ */
 
 /*
- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -44,17 +44,19 @@
 #include "session.h"
 #include "misc.h"
 #include "servconf.h"
+#include "uidswap.h"
 
 #include "ssh-gss.h"
+#include "monitor_wrap.h"
 
 extern ServerOptions options;
 
 static ssh_gssapi_client gssapi_client =
-    { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
-    GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}};
+    { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, GSS_C_NO_CREDENTIAL,
+    GSS_C_NO_NAME, NULL, {NULL, NULL, NULL, NULL, NULL}, 0, 0};
 
 ssh_gssapi_mech gssapi_null_mech =
-    { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
+    { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL};
 
 #ifdef KRB5
 extern ssh_gssapi_mech gssapi_kerberos_mech;
@@ -140,6 +142,29 @@ ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
 	return (ssh_gssapi_acquire_cred(*ctx));
 }
 
+/* Unprivileged */
+char *
+ssh_gssapi_server_mechanisms(void) {
+	if (supported_oids == NULL)
+		ssh_gssapi_prepare_supported_oids();
+	return (ssh_gssapi_kex_mechs(supported_oids,
+	    &ssh_gssapi_server_check_mech, NULL, NULL,
+	    options.gss_kex_algorithms));
+}
+
+/* Unprivileged */
+int
+ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data,
+    const char *dummy) {
+	Gssctxt *ctx = NULL;
+	int res;
+
+	res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
+	ssh_gssapi_delete_ctx(&ctx);
+
+	return (res);
+}
+
 /* Unprivileged */
 void
 ssh_gssapi_supported_oids(gss_OID_set *oidset)
@@ -150,7 +175,9 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset)
 	gss_OID_set supported;
 
 	gss_create_empty_oid_set(&min_status, oidset);
-	gss_indicate_mechs(&min_status, &supported);
+
+	if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported)))
+		return;
 
 	while (supported_mechs[i]->name != NULL) {
 		if (GSS_ERROR(gss_test_oid_set_member(&min_status,
@@ -276,8 +303,48 @@ OM_uint32
 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
 {
 	int i = 0;
+	int equal = 0;
+	gss_name_t new_name = GSS_C_NO_NAME;
+	gss_buffer_desc ename = GSS_C_EMPTY_BUFFER;
+
+	if (options.gss_store_rekey && client->used && ctx->client_creds) {
+		if (client->mech->oid.length != ctx->oid->length ||
+		    (memcmp(client->mech->oid.elements,
+		     ctx->oid->elements, ctx->oid->length) !=0)) {
+			debug("Rekeyed credentials have different mechanism");
+			return GSS_S_COMPLETE;
+		}
+
+		if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
+		    ctx->client_creds, ctx->oid, &new_name,
+		    NULL, NULL, NULL))) {
+			ssh_gssapi_error(ctx);
+			return (ctx->major);
+		}
+
+		ctx->major = gss_compare_name(&ctx->minor, client->name,
+		    new_name, &equal);
+
+		if (GSS_ERROR(ctx->major)) {
+			ssh_gssapi_error(ctx);
+			return (ctx->major);
+		}
+
+		if (!equal) {
+			debug("Rekeyed credentials have different name");
+			return GSS_S_COMPLETE;
+		}
 
-	gss_buffer_desc ename;
+		debug("Marking rekeyed credentials for export");
+
+		gss_release_name(&ctx->minor, &client->name);
+		gss_release_cred(&ctx->minor, &client->creds);
+		client->name = new_name;
+		client->creds = ctx->client_creds;
+		ctx->client_creds = GSS_C_NO_CREDENTIAL;
+		client->updated = 1;
+		return GSS_S_COMPLETE;
+	}
 
 	client->mech = NULL;
 
@@ -292,6 +359,13 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
 	if (client->mech == NULL)
 		return GSS_S_FAILURE;
 
+	if (ctx->client_creds &&
+	    (ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
+	     ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) {
+		ssh_gssapi_error(ctx);
+		return (ctx->major);
+	}
+
 	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
 	    &client->displayname, NULL))) {
 		ssh_gssapi_error(ctx);
@@ -309,6 +383,8 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
 		return (ctx->major);
 	}
 
+	gss_release_buffer(&ctx->minor, &ename);
+
 	/* We can't copy this structure, so we just move the pointer to it */
 	client->creds = ctx->client_creds;
 	ctx->client_creds = GSS_C_NO_CREDENTIAL;
@@ -356,19 +432,23 @@ ssh_gssapi_do_child(char ***envp, u_int *envsizep)
 
 /* Privileged */
 int
-ssh_gssapi_userok(char *user)
+ssh_gssapi_userok(char *user, struct passwd *pw, int kex)
 {
 	OM_uint32 lmin;
 
+	(void) kex; /* used in privilege separation */
+
 	if (gssapi_client.exportedname.length == 0 ||
 	    gssapi_client.exportedname.value == NULL) {
 		debug("No suitable client data");
 		return 0;
 	}
 	if (gssapi_client.mech && gssapi_client.mech->userok)
-		if ((*gssapi_client.mech->userok)(&gssapi_client, user))
+		if ((*gssapi_client.mech->userok)(&gssapi_client, user)) {
+			gssapi_client.used = 1;
+			gssapi_client.store.owner = pw;
 			return 1;
-		else {
+		} else {
 			/* Destroy delegated credentials if userok fails */
 			gss_release_buffer(&lmin, &gssapi_client.displayname);
 			gss_release_buffer(&lmin, &gssapi_client.exportedname);
@@ -382,14 +462,90 @@ ssh_gssapi_userok(char *user)
 	return (0);
 }
 
-/* Privileged */
-OM_uint32
-ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
+/* These bits are only used for rekeying. The unpriviledged child is running
+ * as the user, the monitor is root.
+ *
+ * In the child, we want to :
+ *    *) Ask the monitor to store our credentials into the store we specify
+ *    *) If it succeeds, maybe do a PAM update
+ */
+
+/* Stuff for PAM */
+
+#ifdef USE_PAM
+static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg,
+    struct pam_response **resp, void *data)
 {
-	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
-	    gssbuf, gssmic, NULL);
+	return (PAM_CONV_ERR);
+}
+#endif
 
-	return (ctx->major);
+void
+ssh_gssapi_rekey_creds(void) {
+	int ok;
+#ifdef USE_PAM
+	int ret;
+	pam_handle_t *pamh = NULL;
+	struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL};
+	char *envstr;
+#endif
+
+	if (gssapi_client.store.filename == NULL &&
+	    gssapi_client.store.envval == NULL &&
+	    gssapi_client.store.envvar == NULL)
+		return;
+
+	ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store));
+
+	if (!ok)
+		return;
+
+	debug("Rekeyed credentials stored successfully");
+
+	/* Actually managing to play with the ssh pam stack from here will
+	 * be next to impossible. In any case, we may want different options
+	 * for rekeying. So, use our own :)
+	 */
+#ifdef USE_PAM	
+	if (!use_privsep) {
+		debug("Not even going to try and do PAM with privsep disabled");
+		return;
+	}
+
+	ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name,
+ 	    &pamconv, &pamh);
+	if (ret)
+		return;
+
+	xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar,
+	    gssapi_client.store.envval);
+
+	ret = pam_putenv(pamh, envstr);
+	if (!ret)
+		pam_setcred(pamh, PAM_REINITIALIZE_CRED);
+	pam_end(pamh, PAM_SUCCESS);
+#endif
+}
+
+int
+ssh_gssapi_update_creds(ssh_gssapi_ccache *store) {
+	int ok = 0;
+
+	/* Check we've got credentials to store */
+	if (!gssapi_client.updated)
+		return 0;
+
+	gssapi_client.updated = 0;
+
+	temporarily_use_uid(gssapi_client.store.owner);
+	if (gssapi_client.mech && gssapi_client.mech->updatecreds)
+		ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client);
+	else
+		debug("No update function for this mechanism");
+
+	restore_uid();
+
+	return ok;
 }
 
 /* Privileged */
diff --git a/kex.c b/kex.c
index ce85f0439..574c76093 100644
--- a/kex.c
+++ b/kex.c
@@ -57,11 +57,16 @@
 #include "misc.h"
 #include "dispatch.h"
 #include "monitor.h"
+#include "xmalloc.h"
 
 #include "ssherr.h"
 #include "sshbuf.h"
 #include "digest.h"
 
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+
 /* prototype */
 static int kex_choose_conf(struct ssh *);
 static int kex_input_newkeys(int, u_int32_t, struct ssh *);
@@ -115,15 +120,28 @@ static const struct kexalg kexalgs[] = {
 #endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
 	{ NULL, 0, -1, -1},
 };
+static const struct kexalg gss_kexalgs[] = {
+#ifdef GSSAPI
+	{ KEX_GSS_GEX_SHA1_ID, KEX_GSS_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
+	{ KEX_GSS_GRP1_SHA1_ID, KEX_GSS_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
+	{ KEX_GSS_GRP14_SHA1_ID, KEX_GSS_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
+	{ KEX_GSS_GRP14_SHA256_ID, KEX_GSS_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
+	{ KEX_GSS_GRP16_SHA512_ID, KEX_GSS_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
+	{ KEX_GSS_NISTP256_SHA256_ID, KEX_GSS_NISTP256_SHA256,
+	    NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
+	{ KEX_GSS_C25519_SHA256_ID, KEX_GSS_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
+#endif
+	{ NULL, 0, -1, -1},
+};
 
-char *
-kex_alg_list(char sep)
+static char *
+kex_alg_list_internal(char sep, const struct kexalg *algs)
 {
 	char *ret = NULL, *tmp;
 	size_t nlen, rlen = 0;
 	const struct kexalg *k;
 
-	for (k = kexalgs; k->name != NULL; k++) {
+	for (k = algs; k->name != NULL; k++) {
 		if (ret != NULL)
 			ret[rlen++] = sep;
 		nlen = strlen(k->name);
@@ -138,6 +156,18 @@ kex_alg_list(char sep)
 	return ret;
 }
 
+char *
+kex_alg_list(char sep)
+{
+	return kex_alg_list_internal(sep, kexalgs);
+}
+
+char *
+kex_gss_alg_list(char sep)
+{
+	return kex_alg_list_internal(sep, gss_kexalgs);
+}
+
 static const struct kexalg *
 kex_alg_by_name(const char *name)
 {
@@ -147,6 +177,10 @@ kex_alg_by_name(const char *name)
 		if (strcmp(k->name, name) == 0)
 			return k;
 	}
+	for (k = gss_kexalgs; k->name != NULL; k++) {
+		if (strncmp(k->name, name, strlen(k->name)) == 0)
+			return k;
+	}
 	return NULL;
 }
 
@@ -315,6 +349,29 @@ kex_assemble_names(char **listp, const char *def, const char *all)
 	return r;
 }
 
+/* Validate GSS KEX method name list */
+int
+kex_gss_names_valid(const char *names)
+{
+	char *s, *cp, *p;
+
+	if (names == NULL || *names == '\0')
+		return 0;
+	s = cp = xstrdup(names);
+	for ((p = strsep(&cp, ",")); p && *p != '\0';
+	    (p = strsep(&cp, ","))) {
+		if (strncmp(p, "gss-", 4) != 0
+		  || kex_alg_by_name(p) == NULL) {
+			error("Unsupported KEX algorithm \"%.100s\"", p);
+			free(s);
+			return 0;
+		}
+	}
+	debug3("gss kex names ok: [%s]", names);
+	free(s);
+	return 1;
+}
+
 /* put algorithm proposal into buffer */
 int
 kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
@@ -698,6 +755,9 @@ kex_free(struct kex *kex)
 	sshbuf_free(kex->server_version);
 	sshbuf_free(kex->client_pub);
 	free(kex->session_id);
+#ifdef GSSAPI
+	free(kex->gss_host);
+#endif /* GSSAPI */
 	free(kex->failed_choice);
 	free(kex->hostkey_alg);
 	free(kex->name);
diff --git a/kex.h b/kex.h
index a5ae6ac05..fe7141414 100644
--- a/kex.h
+++ b/kex.h
@@ -102,6 +102,15 @@ enum kex_exchange {
 	KEX_ECDH_SHA2,
 	KEX_C25519_SHA256,
 	KEX_KEM_SNTRUP4591761X25519_SHA512,
+#ifdef GSSAPI
+	KEX_GSS_GRP1_SHA1,
+	KEX_GSS_GRP14_SHA1,
+	KEX_GSS_GRP14_SHA256,
+	KEX_GSS_GRP16_SHA512,
+	KEX_GSS_GEX_SHA1,
+	KEX_GSS_NISTP256_SHA256,
+	KEX_GSS_C25519_SHA256,
+#endif
 	KEX_MAX
 };
 
@@ -153,6 +162,12 @@ struct kex {
 	u_int	flags;
 	int	hash_alg;
 	int	ec_nid;
+#ifdef GSSAPI
+	int	gss_deleg_creds;
+	int	gss_trust_dns;
+	char    *gss_host;
+	char	*gss_client;
+#endif
 	char	*failed_choice;
 	int	(*verify_host_key)(struct sshkey *, struct ssh *);
 	struct sshkey *(*load_host_public_key)(int, int, struct ssh *);
@@ -174,8 +189,10 @@ struct kex {
 
 int	 kex_names_valid(const char *);
 char	*kex_alg_list(char);
+char	*kex_gss_alg_list(char);
 char	*kex_names_cat(const char *, const char *);
 int	 kex_assemble_names(char **, const char *, const char *);
+int	 kex_gss_names_valid(const char *);
 
 int	 kex_exchange_identification(struct ssh *, int, const char *);
 
@@ -202,6 +219,12 @@ int	 kexgex_client(struct ssh *);
 int	 kexgex_server(struct ssh *);
 int	 kex_gen_client(struct ssh *);
 int	 kex_gen_server(struct ssh *);
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+int	 kexgssgex_client(struct ssh *);
+int	 kexgssgex_server(struct ssh *);
+int	 kexgss_client(struct ssh *);
+int	 kexgss_server(struct ssh *);
+#endif
 
 int	 kex_dh_keypair(struct kex *);
 int	 kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
@@ -234,6 +257,12 @@ int	 kexgex_hash(int, const struct sshbuf *, const struct sshbuf *,
     const BIGNUM *, const u_char *, size_t,
     u_char *, size_t *);
 
+int	 kex_gen_hash(int hash_alg, const struct sshbuf *client_version,
+    const struct sshbuf *server_version, const struct sshbuf *client_kexinit,
+    const struct sshbuf *server_kexinit, const struct sshbuf *server_host_key_blob,
+    const struct sshbuf *client_pub, const struct sshbuf *server_pub,
+    const struct sshbuf *shared_secret, u_char *hash, size_t *hashlen);
+
 void	kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
 	__attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
 	__attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));
diff --git a/kexdh.c b/kexdh.c
index 67133e339..edaa46762 100644
--- a/kexdh.c
+++ b/kexdh.c
@@ -48,13 +48,23 @@ kex_dh_keygen(struct kex *kex)
 {
 	switch (kex->kex_type) {
 	case KEX_DH_GRP1_SHA1:
+#ifdef GSSAPI
+	case KEX_GSS_GRP1_SHA1:
+#endif
 		kex->dh = dh_new_group1();
 		break;
 	case KEX_DH_GRP14_SHA1:
 	case KEX_DH_GRP14_SHA256:
+#ifdef GSSAPI
+	case KEX_GSS_GRP14_SHA1:
+	case KEX_GSS_GRP14_SHA256:
+#endif
 		kex->dh = dh_new_group14();
 		break;
 	case KEX_DH_GRP16_SHA512:
+#ifdef GSSAPI
+	case KEX_GSS_GRP16_SHA512:
+#endif
 		kex->dh = dh_new_group16();
 		break;
 	case KEX_DH_GRP18_SHA512:
diff --git a/kexgen.c b/kexgen.c
index 69348b964..c0e8c2f44 100644
--- a/kexgen.c
+++ b/kexgen.c
@@ -44,7 +44,7 @@
 static int input_kex_gen_init(int, u_int32_t, struct ssh *);
 static int input_kex_gen_reply(int type, u_int32_t seq, struct ssh *ssh);
 
-static int
+int
 kex_gen_hash(
     int hash_alg,
     const struct sshbuf *client_version,
diff --git a/kexgssc.c b/kexgssc.c
new file mode 100644
index 000000000..f6e1405eb
--- /dev/null
+++ b/kexgssc.c
@@ -0,0 +1,606 @@
+/*
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+
+#include "includes.h"
+
+#include <openssl/crypto.h>
+#include <openssl/bn.h>
+
+#include <string.h>
+
+#include "xmalloc.h"
+#include "sshbuf.h"
+#include "ssh2.h"
+#include "sshkey.h"
+#include "cipher.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "dh.h"
+#include "digest.h"
+#include "ssherr.h"
+
+#include "ssh-gss.h"
+
+int
+kexgss_client(struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER,
+	    recv_tok = GSS_C_EMPTY_BUFFER,
+	    gssbuf, msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr;
+	Gssctxt *ctxt;
+	OM_uint32 maj_status, min_status, ret_flags;
+	struct sshbuf *server_blob = NULL;
+	struct sshbuf *shared_secret = NULL;
+	struct sshbuf *server_host_key_blob = NULL;
+	struct sshbuf *empty = NULL;
+	u_char *msg;
+	int type = 0;
+	int first = 1;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t hashlen;
+	u_char c;
+	int r;
+
+	/* Initialise our GSSAPI world */
+	ssh_gssapi_build_ctx(&ctxt);
+	if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type)
+	    == GSS_C_NO_OID)
+		fatal("Couldn't identify host exchange");
+
+	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
+		fatal("Couldn't import hostname");
+
+	if (kex->gss_client &&
+	    ssh_gssapi_client_identity(ctxt, kex->gss_client))
+		fatal("Couldn't acquire client credentials");
+
+	/* Step 1 */
+	switch (kex->kex_type) {
+	case KEX_GSS_GRP1_SHA1:
+	case KEX_GSS_GRP14_SHA1:
+	case KEX_GSS_GRP14_SHA256:
+	case KEX_GSS_GRP16_SHA512:
+		r = kex_dh_keypair(kex);
+		break;
+	case KEX_GSS_NISTP256_SHA256:
+		r = kex_ecdh_keypair(kex);
+		break;
+	case KEX_GSS_C25519_SHA256:
+		r = kex_c25519_keypair(kex);
+		break;
+	default:
+		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
+	}
+	if (r != 0)
+		return r;
+
+	token_ptr = GSS_C_NO_BUFFER;
+
+	do {
+		debug("Calling gss_init_sec_context");
+
+		maj_status = ssh_gssapi_init_ctx(ctxt,
+		    kex->gss_deleg_creds, token_ptr, &send_tok,
+		    &ret_flags);
+
+		if (GSS_ERROR(maj_status)) {
+			/* XXX Useles code: Missing send? */
+			if (send_tok.length != 0) {
+				if ((r = sshpkt_start(ssh,
+				        SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+				    (r = sshpkt_put_string(ssh, send_tok.value,
+				        send_tok.length)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+			}
+			fatal("gss_init_context failed");
+		}
+
+		/* If we've got an old receive buffer get rid of it */
+		if (token_ptr != GSS_C_NO_BUFFER)
+			gss_release_buffer(&min_status, &recv_tok);
+
+		if (maj_status == GSS_S_COMPLETE) {
+			/* If mutual state flag is not true, kex fails */
+			if (!(ret_flags & GSS_C_MUTUAL_FLAG))
+				fatal("Mutual authentication failed");
+
+			/* If integ avail flag is not true kex fails */
+			if (!(ret_flags & GSS_C_INTEG_FLAG))
+				fatal("Integrity check failed");
+		}
+
+		/*
+		 * If we have data to send, then the last message that we
+		 * received cannot have been a 'complete'.
+		 */
+		if (send_tok.length != 0) {
+			if (first) {
+				if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 ||
+				    (r = sshpkt_put_string(ssh, send_tok.value,
+				        send_tok.length)) != 0 ||
+				    (r = sshpkt_put_stringb(ssh, kex->client_pub)) != 0)
+					fatal("failed to construct packet: %s", ssh_err(r));
+				first = 0;
+			} else {
+				if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+				    (r = sshpkt_put_string(ssh, send_tok.value,
+				        send_tok.length)) != 0)
+					fatal("failed to construct packet: %s", ssh_err(r));
+			}
+			if ((r = sshpkt_send(ssh)) != 0)
+				fatal("failed to send packet: %s", ssh_err(r));
+			gss_release_buffer(&min_status, &send_tok);
+
+			/* If we've sent them data, they should reply */
+			do {
+				type = ssh_packet_read(ssh);
+				if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
+					debug("Received KEXGSS_HOSTKEY");
+					if (server_host_key_blob)
+						fatal("Server host key received more than once");
+					if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
+						fatal("Failed to read server host key: %s", ssh_err(r));
+				}
+			} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
+
+			switch (type) {
+			case SSH2_MSG_KEXGSS_CONTINUE:
+				debug("Received GSSAPI_CONTINUE");
+				if (maj_status == GSS_S_COMPLETE)
+					fatal("GSSAPI Continue received from server when complete");
+				if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+				        &recv_tok)) != 0 ||
+				    (r = sshpkt_get_end(ssh)) != 0)
+					fatal("Failed to read token: %s", ssh_err(r));
+				break;
+			case SSH2_MSG_KEXGSS_COMPLETE:
+				debug("Received GSSAPI_COMPLETE");
+				if (msg_tok.value != NULL)
+				        fatal("Received GSSAPI_COMPLETE twice?");
+				if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 ||
+				    (r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+				        &msg_tok)) != 0)
+					fatal("Failed to read message: %s", ssh_err(r));
+
+				/* Is there a token included? */
+				if ((r = sshpkt_get_u8(ssh, &c)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+				if (c) {
+					if ((r = ssh_gssapi_sshpkt_get_buffer_desc(
+					    ssh, &recv_tok)) != 0)
+						fatal("Failed to read token: %s", ssh_err(r));
+					/* If we're already complete - protocol error */
+					if (maj_status == GSS_S_COMPLETE)
+						sshpkt_disconnect(ssh, "Protocol error: received token when complete");
+				} else {
+					/* No token included */
+					if (maj_status != GSS_S_COMPLETE)
+						sshpkt_disconnect(ssh, "Protocol error: did not receive final token");
+				}
+				if ((r = sshpkt_get_end(ssh)) != 0) {
+					fatal("Expecting end of packet.");
+				}
+				break;
+			case SSH2_MSG_KEXGSS_ERROR:
+				debug("Received Error");
+				if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 ||
+				    (r = sshpkt_get_u32(ssh, &min_status)) != 0 ||
+				    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
+				    (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */
+				    (r = sshpkt_get_end(ssh)) != 0)
+					fatal("sshpkt_get failed: %s", ssh_err(r));
+				fatal("GSSAPI Error: \n%.400s", msg);
+			default:
+				sshpkt_disconnect(ssh, "Protocol error: didn't expect packet type %d",
+				    type);
+			}
+			token_ptr = &recv_tok;
+		} else {
+			/* No data, and not complete */
+			if (maj_status != GSS_S_COMPLETE)
+				fatal("Not complete, and no token output");
+		}
+	} while (maj_status & GSS_S_CONTINUE_NEEDED);
+
+	/*
+	 * We _must_ have received a COMPLETE message in reply from the
+	 * server, which will have set server_blob and msg_tok
+	 */
+
+	if (type != SSH2_MSG_KEXGSS_COMPLETE)
+		fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
+
+	/* compute shared secret */
+	switch (kex->kex_type) {
+	case KEX_GSS_GRP1_SHA1:
+	case KEX_GSS_GRP14_SHA1:
+	case KEX_GSS_GRP14_SHA256:
+	case KEX_GSS_GRP16_SHA512:
+		r = kex_dh_dec(kex, server_blob, &shared_secret);
+		break;
+	case KEX_GSS_C25519_SHA256:
+		if (sshbuf_ptr(server_blob)[sshbuf_len(server_blob)] & 0x80)
+			fatal("The received key has MSB of last octet set!");
+		r = kex_c25519_dec(kex, server_blob, &shared_secret);
+		break;
+	case KEX_GSS_NISTP256_SHA256:
+		if (sshbuf_len(server_blob) != 65)
+			fatal("The received NIST-P256 key did not match"
+			    "expected length (expected 65, got %zu)", sshbuf_len(server_blob));
+
+		if (sshbuf_ptr(server_blob)[0] != POINT_CONVERSION_UNCOMPRESSED)
+			fatal("The received NIST-P256 key does not have first octet 0x04");
+
+		r = kex_ecdh_dec(kex, server_blob, &shared_secret);
+		break;
+	default:
+		r = SSH_ERR_INVALID_ARGUMENT;
+		break;
+	}
+	if (r != 0)
+		goto out;
+
+	if ((empty = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+
+	hashlen = sizeof(hash);
+	if ((r = kex_gen_hash(
+	    kex->hash_alg,
+	    kex->client_version,
+	    kex->server_version,
+	    kex->my,
+	    kex->peer,
+	    (server_host_key_blob ? server_host_key_blob : empty),
+	    kex->client_pub,
+	    server_blob,
+	    shared_secret,
+	    hash, &hashlen)) != 0)
+		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
+
+	gssbuf.value = hash;
+	gssbuf.length = hashlen;
+
+	/* Verify that the hash matches the MIC we just got. */
+	if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
+		sshpkt_disconnect(ssh, "Hash's MIC didn't verify");
+
+	gss_release_buffer(&min_status, &msg_tok);
+
+	if (kex->gss_deleg_creds)
+		ssh_gssapi_credentials_updated(ctxt);
+
+	if (gss_kex_context == NULL)
+		gss_kex_context = ctxt;
+	else
+		ssh_gssapi_delete_ctx(&ctxt);
+
+	if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+
+out:
+	explicit_bzero(hash, sizeof(hash));
+	explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
+	sshbuf_free(empty);
+	sshbuf_free(server_host_key_blob);
+	sshbuf_free(server_blob);
+	sshbuf_free(shared_secret);
+	sshbuf_free(kex->client_pub);
+	kex->client_pub = NULL;
+	return r;
+}
+
+int
+kexgssgex_client(struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER,
+	    recv_tok = GSS_C_EMPTY_BUFFER, gssbuf,
+            msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr;
+	Gssctxt *ctxt;
+	OM_uint32 maj_status, min_status, ret_flags;
+	struct sshbuf *shared_secret = NULL;
+	BIGNUM *p = NULL;
+	BIGNUM *g = NULL;
+	struct sshbuf *buf = NULL;
+	struct sshbuf *server_host_key_blob = NULL;
+	struct sshbuf *server_blob = NULL;
+	BIGNUM *dh_server_pub = NULL;
+	u_char *msg;
+	int type = 0;
+	int first = 1;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t hashlen;
+	const BIGNUM *pub_key, *dh_p, *dh_g;
+	int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
+	struct sshbuf *empty = NULL;
+	u_char c;
+	int r;
+
+	/* Initialise our GSSAPI world */
+	ssh_gssapi_build_ctx(&ctxt);
+	if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type)
+	    == GSS_C_NO_OID)
+		fatal("Couldn't identify host exchange");
+
+	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
+		fatal("Couldn't import hostname");
+
+	if (kex->gss_client &&
+	    ssh_gssapi_client_identity(ctxt, kex->gss_client))
+		fatal("Couldn't acquire client credentials");
+
+	debug("Doing group exchange");
+	nbits = dh_estimate(kex->dh_need * 8);
+
+	kex->min = DH_GRP_MIN;
+	kex->max = DH_GRP_MAX;
+	kex->nbits = nbits;
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUPREQ)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, min)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, nbits)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, max)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("Failed to construct a packet: %s", ssh_err(r));
+
+	if ((r = ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0)
+		fatal("Error: %s", ssh_err(r));
+
+	if ((r = sshpkt_get_bignum2(ssh, &p)) != 0 ||
+	    (r = sshpkt_get_bignum2(ssh, &g)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		fatal("shpkt_get_bignum2 failed: %s", ssh_err(r));
+
+	if (BN_num_bits(p) < min || BN_num_bits(p) > max)
+		fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
+		    min, BN_num_bits(p), max);
+
+	if ((kex->dh = dh_new_group(g, p)) == NULL)
+		fatal("dn_new_group() failed");
+	p = g = NULL; /* belong to kex->dh now */
+
+	if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
+		goto out;
+	DH_get0_key(kex->dh, &pub_key, NULL);
+
+	token_ptr = GSS_C_NO_BUFFER;
+
+	do {
+		/* Step 2 - call GSS_Init_sec_context() */
+		debug("Calling gss_init_sec_context");
+
+		maj_status = ssh_gssapi_init_ctx(ctxt,
+		    kex->gss_deleg_creds, token_ptr, &send_tok,
+		    &ret_flags);
+
+		if (GSS_ERROR(maj_status)) {
+			/* XXX Useles code: Missing send? */
+			if (send_tok.length != 0) {
+				if ((r = sshpkt_start(ssh,
+				        SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+				    (r = sshpkt_put_string(ssh, send_tok.value,
+				        send_tok.length)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+			}
+			fatal("gss_init_context failed");
+		}
+
+		/* If we've got an old receive buffer get rid of it */
+		if (token_ptr != GSS_C_NO_BUFFER)
+			gss_release_buffer(&min_status, &recv_tok);
+
+		if (maj_status == GSS_S_COMPLETE) {
+			/* If mutual state flag is not true, kex fails */
+			if (!(ret_flags & GSS_C_MUTUAL_FLAG))
+				fatal("Mutual authentication failed");
+
+			/* If integ avail flag is not true kex fails */
+			if (!(ret_flags & GSS_C_INTEG_FLAG))
+				fatal("Integrity check failed");
+		}
+
+		/*
+		 * If we have data to send, then the last message that we
+		 * received cannot have been a 'complete'.
+		 */
+		if (send_tok.length != 0) {
+			if (first) {
+				if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 ||
+				    (r = sshpkt_put_string(ssh, send_tok.value,
+				        send_tok.length)) != 0 ||
+				    (r = sshpkt_put_bignum2(ssh, pub_key)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+				first = 0;
+			} else {
+				if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+				    (r = sshpkt_put_string(ssh,send_tok.value,
+				        send_tok.length)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+			}
+			if ((r = sshpkt_send(ssh)) != 0)
+				fatal("sshpkt_send failed: %s", ssh_err(r));
+			gss_release_buffer(&min_status, &send_tok);
+
+			/* If we've sent them data, they should reply */
+			do {
+				type = ssh_packet_read(ssh);
+				if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
+					debug("Received KEXGSS_HOSTKEY");
+					if (server_host_key_blob)
+						fatal("Server host key received more than once");
+					if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
+						fatal("sshpkt failed: %s", ssh_err(r));
+				}
+			} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
+
+			switch (type) {
+			case SSH2_MSG_KEXGSS_CONTINUE:
+				debug("Received GSSAPI_CONTINUE");
+				if (maj_status == GSS_S_COMPLETE)
+					fatal("GSSAPI Continue received from server when complete");
+				if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+				        &recv_tok)) != 0 ||
+				    (r = sshpkt_get_end(ssh)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+				break;
+			case SSH2_MSG_KEXGSS_COMPLETE:
+				debug("Received GSSAPI_COMPLETE");
+				if (msg_tok.value != NULL)
+				        fatal("Received GSSAPI_COMPLETE twice?");
+				if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 ||
+				    (r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+				        &msg_tok)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+
+				/* Is there a token included? */
+				if ((r = sshpkt_get_u8(ssh, &c)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+				if (c) {
+					if ((r = ssh_gssapi_sshpkt_get_buffer_desc(
+					        ssh, &recv_tok)) != 0 ||
+					    (r = sshpkt_get_end(ssh)) != 0)
+						fatal("sshpkt failed: %s", ssh_err(r));
+					/* If we're already complete - protocol error */
+					if (maj_status == GSS_S_COMPLETE)
+						sshpkt_disconnect(ssh, "Protocol error: received token when complete");
+				} else {
+					/* No token included */
+					if (maj_status != GSS_S_COMPLETE)
+						sshpkt_disconnect(ssh, "Protocol error: did not receive final token");
+				}
+				break;
+			case SSH2_MSG_KEXGSS_ERROR:
+				debug("Received Error");
+				if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 ||
+				    (r = sshpkt_get_u32(ssh, &min_status)) != 0 ||
+				    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
+				    (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */
+				    (r = sshpkt_get_end(ssh)) != 0)
+					fatal("sshpkt failed: %s", ssh_err(r));
+				fatal("GSSAPI Error: \n%.400s", msg);
+			default:
+				sshpkt_disconnect(ssh, "Protocol error: didn't expect packet type %d",
+				    type);
+			}
+			token_ptr = &recv_tok;
+		} else {
+			/* No data, and not complete */
+			if (maj_status != GSS_S_COMPLETE)
+				fatal("Not complete, and no token output");
+		}
+	} while (maj_status & GSS_S_CONTINUE_NEEDED);
+
+	/*
+	 * We _must_ have received a COMPLETE message in reply from the
+	 * server, which will have set dh_server_pub and msg_tok
+	 */
+
+	if (type != SSH2_MSG_KEXGSS_COMPLETE)
+		fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
+
+	/* 7. C verifies that the key Q_S is valid */
+	/* 8. C computes shared secret */
+	if ((buf = sshbuf_new()) == NULL ||
+	    (r = sshbuf_put_stringb(buf, server_blob)) != 0 ||
+	    (r = sshbuf_get_bignum2(buf, &dh_server_pub)) != 0)
+		goto out;
+	sshbuf_free(buf);
+	buf = NULL;
+
+	if ((shared_secret = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+
+	if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0)
+		goto out;
+	if ((empty = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+
+	DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
+	hashlen = sizeof(hash);
+	if ((r = kexgex_hash(
+	    kex->hash_alg,
+	    kex->client_version,
+	    kex->server_version,
+	    kex->my,
+	    kex->peer,
+	    (server_host_key_blob ? server_host_key_blob : empty),
+ 	    kex->min, kex->nbits, kex->max,
+	    dh_p, dh_g,
+	    pub_key,
+	    dh_server_pub,
+	    sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
+	    hash, &hashlen)) != 0)
+		fatal("Failed to calculate hash: %s", ssh_err(r));
+
+	gssbuf.value = hash;
+	gssbuf.length = hashlen;
+
+	/* Verify that the hash matches the MIC we just got. */
+	if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
+		sshpkt_disconnect(ssh, "Hash's MIC didn't verify");
+
+	gss_release_buffer(&min_status, &msg_tok);
+
+	/* save session id */
+	if (kex->session_id == NULL) {
+		kex->session_id_len = hashlen;
+		kex->session_id = xmalloc(kex->session_id_len);
+		memcpy(kex->session_id, hash, kex->session_id_len);
+	}
+
+	if (kex->gss_deleg_creds)
+		ssh_gssapi_credentials_updated(ctxt);
+
+	if (gss_kex_context == NULL)
+		gss_kex_context = ctxt;
+	else
+		ssh_gssapi_delete_ctx(&ctxt);
+
+	/* Finally derive the keys and send them */
+	if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+out:
+	sshbuf_free(buf);
+	sshbuf_free(server_blob);
+	sshbuf_free(empty);
+	explicit_bzero(hash, sizeof(hash));
+	DH_free(kex->dh);
+	kex->dh = NULL;
+	BN_clear_free(dh_server_pub);
+	sshbuf_free(shared_secret);
+	sshbuf_free(server_host_key_blob);
+	return r;
+}
+#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */
diff --git a/kexgsss.c b/kexgsss.c
new file mode 100644
index 000000000..60bc02deb
--- /dev/null
+++ b/kexgsss.c
@@ -0,0 +1,474 @@
+/*
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+
+#include <string.h>
+
+#include <openssl/crypto.h>
+#include <openssl/bn.h>
+
+#include "xmalloc.h"
+#include "sshbuf.h"
+#include "ssh2.h"
+#include "sshkey.h"
+#include "cipher.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "dh.h"
+#include "ssh-gss.h"
+#include "monitor_wrap.h"
+#include "misc.h"      /* servconf.h needs misc.h for struct ForwardOptions */
+#include "servconf.h"
+#include "ssh-gss.h"
+#include "digest.h"
+#include "ssherr.h"
+
+extern ServerOptions options;
+
+int
+kexgss_server(struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	OM_uint32 maj_status, min_status;
+
+	/*
+	 * Some GSSAPI implementations use the input value of ret_flags (an
+	 * output variable) as a means of triggering mechanism specific
+	 * features. Initializing it to zero avoids inadvertently
+	 * activating this non-standard behaviour.
+	 */
+
+	OM_uint32 ret_flags = 0;
+	gss_buffer_desc gssbuf, recv_tok, msg_tok;
+	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+	Gssctxt *ctxt = NULL;
+	struct sshbuf *shared_secret = NULL;
+	struct sshbuf *client_pubkey = NULL;
+	struct sshbuf *server_pubkey = NULL;
+	struct sshbuf *empty = sshbuf_new();
+	int type = 0;
+	gss_OID oid;
+	char *mechs;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t hashlen;
+	int r;
+
+	/* Initialise GSSAPI */
+
+	/* If we're rekeying, privsep means that some of the private structures
+	 * in the GSSAPI code are no longer available. This kludges them back
+	 * into life
+	 */
+	if (!ssh_gssapi_oid_table_ok()) {
+		mechs = ssh_gssapi_server_mechanisms();
+		free(mechs);
+	}
+
+	debug2("%s: Identifying %s", __func__, kex->name);
+	oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
+	if (oid == GSS_C_NO_OID)
+	   fatal("Unknown gssapi mechanism");
+
+	debug2("%s: Acquiring credentials", __func__);
+
+	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
+		fatal("Unable to acquire credentials for the server");
+
+	do {
+		debug("Wait SSH2_MSG_KEXGSS_INIT");
+		type = ssh_packet_read(ssh);
+		switch(type) {
+		case SSH2_MSG_KEXGSS_INIT:
+			if (client_pubkey != NULL)
+				fatal("Received KEXGSS_INIT after initialising");
+			if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+			        &recv_tok)) != 0 ||
+			    (r = sshpkt_getb_froms(ssh, &client_pubkey)) != 0 ||
+			    (r = sshpkt_get_end(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+
+			switch (kex->kex_type) {
+			case KEX_GSS_GRP1_SHA1:
+			case KEX_GSS_GRP14_SHA1:
+			case KEX_GSS_GRP14_SHA256:
+			case KEX_GSS_GRP16_SHA512:
+				r = kex_dh_enc(kex, client_pubkey, &server_pubkey,
+				    &shared_secret);
+				break;
+			case KEX_GSS_NISTP256_SHA256:
+				r = kex_ecdh_enc(kex, client_pubkey, &server_pubkey,
+				    &shared_secret);
+				break;
+			case KEX_GSS_C25519_SHA256:
+				r = kex_c25519_enc(kex, client_pubkey, &server_pubkey,
+				    &shared_secret);
+				break;
+			default:
+				fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
+			}
+			if (r != 0)
+				goto out;
+
+			/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
+			break;
+		case SSH2_MSG_KEXGSS_CONTINUE:
+			if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+			        &recv_tok)) != 0 ||
+			    (r = sshpkt_get_end(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+			break;
+		default:
+			sshpkt_disconnect(ssh,
+			    "Protocol error: didn't expect packet type %d",
+			    type);
+		}
+
+		maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
+		    &send_tok, &ret_flags));
+
+		gss_release_buffer(&min_status, &recv_tok);
+
+		if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
+			fatal("Zero length token output when incomplete");
+
+		if (client_pubkey == NULL)
+			fatal("No client public key");
+
+		if (maj_status & GSS_S_CONTINUE_NEEDED) {
+			debug("Sending GSSAPI_CONTINUE");
+			if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+			    (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+			gss_release_buffer(&min_status, &send_tok);
+		}
+	} while (maj_status & GSS_S_CONTINUE_NEEDED);
+
+	if (GSS_ERROR(maj_status)) {
+		if (send_tok.length > 0) {
+			if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+			    (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+		}
+		fatal("accept_ctx died");
+	}
+
+	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
+		fatal("Mutual Authentication flag wasn't set");
+
+	if (!(ret_flags & GSS_C_INTEG_FLAG))
+		fatal("Integrity flag wasn't set");
+
+	hashlen = sizeof(hash);
+	if ((r = kex_gen_hash(
+	    kex->hash_alg,
+	    kex->client_version,
+	    kex->server_version,
+	    kex->peer,
+	    kex->my,
+	    empty,
+	    client_pubkey,
+	    server_pubkey,
+	    shared_secret,
+	    hash, &hashlen)) != 0)
+		goto out;
+
+	gssbuf.value = hash;
+	gssbuf.length = hashlen;
+
+	if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))))
+		fatal("Couldn't get MIC");
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 ||
+	    (r = sshpkt_put_stringb(ssh, server_pubkey)) != 0 ||
+	    (r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0)
+		fatal("sshpkt failed: %s", ssh_err(r));
+
+	if (send_tok.length != 0) {
+		if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */
+		    (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0)
+			fatal("sshpkt failed: %s", ssh_err(r));
+	} else {
+		if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */
+			fatal("sshpkt failed: %s", ssh_err(r));
+	}
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("sshpkt_send failed: %s", ssh_err(r));
+
+	gss_release_buffer(&min_status, &send_tok);
+	gss_release_buffer(&min_status, &msg_tok);
+
+	if (gss_kex_context == NULL)
+		gss_kex_context = ctxt;
+	else
+		ssh_gssapi_delete_ctx(&ctxt);
+
+	if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+
+	/* If this was a rekey, then save out any delegated credentials we
+	 * just exchanged.  */
+	if (options.gss_store_rekey)
+		ssh_gssapi_rekey_creds();
+out:
+	sshbuf_free(empty);
+	explicit_bzero(hash, sizeof(hash));
+	sshbuf_free(shared_secret);
+	sshbuf_free(client_pubkey);
+	sshbuf_free(server_pubkey);
+	return r;
+}
+
+int
+kexgssgex_server(struct ssh *ssh)
+{
+	struct kex *kex = ssh->kex;
+	OM_uint32 maj_status, min_status;
+
+	/*
+	 * Some GSSAPI implementations use the input value of ret_flags (an
+	 * output variable) as a means of triggering mechanism specific
+	 * features. Initializing it to zero avoids inadvertently
+	 * activating this non-standard behaviour.
+	 */
+
+	OM_uint32 ret_flags = 0;
+	gss_buffer_desc gssbuf, recv_tok, msg_tok;
+	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+	Gssctxt *ctxt = NULL;
+	struct sshbuf *shared_secret = NULL;
+	int type = 0;
+	gss_OID oid;
+	char *mechs;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t hashlen;
+	BIGNUM *dh_client_pub = NULL;
+	const BIGNUM *pub_key, *dh_p, *dh_g;
+	int min = -1, max = -1, nbits = -1;
+	int cmin = -1, cmax = -1; /* client proposal */
+	struct sshbuf *empty = sshbuf_new();
+	int r;
+
+	/* Initialise GSSAPI */
+
+	/* If we're rekeying, privsep means that some of the private structures
+	 * in the GSSAPI code are no longer available. This kludges them back
+	 * into life
+	 */
+	if (!ssh_gssapi_oid_table_ok())
+		if ((mechs = ssh_gssapi_server_mechanisms()))
+			free(mechs);
+
+	debug2("%s: Identifying %s", __func__, kex->name);
+	oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
+	if (oid == GSS_C_NO_OID)
+	   fatal("Unknown gssapi mechanism");
+
+	debug2("%s: Acquiring credentials", __func__);
+
+	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
+		fatal("Unable to acquire credentials for the server");
+
+	/* 5. S generates an ephemeral key pair (do the allocations early) */
+	debug("Doing group exchange");
+	ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUPREQ);
+	/* store client proposal to provide valid signature */
+	if ((r = sshpkt_get_u32(ssh, &cmin)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &cmax)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		fatal("sshpkt failed: %s", ssh_err(r));
+	kex->nbits = nbits;
+	kex->min = cmin;
+	kex->max = cmax;
+	min = MAX(DH_GRP_MIN, cmin);
+	max = MIN(DH_GRP_MAX, cmax);
+	nbits = MAXIMUM(DH_GRP_MIN, nbits);
+	nbits = MINIMUM(DH_GRP_MAX, nbits);
+	if (max < min || nbits < min || max < nbits)
+		fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
+		    min, nbits, max);
+	kex->dh = PRIVSEP(choose_dh(min, nbits, max));
+	if (kex->dh == NULL) {
+		sshpkt_disconnect(ssh, "Protocol error: no matching group found");
+		fatal("Protocol error: no matching group found");
+	}
+
+	DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0 ||
+	    (r = sshpkt_put_bignum2(ssh, dh_p)) != 0 ||
+	    (r = sshpkt_put_bignum2(ssh, dh_g)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("sshpkt failed: %s", ssh_err(r));
+
+	if ((r = ssh_packet_write_wait(ssh)) != 0)
+		fatal("ssh_packet_write_wait: %s", ssh_err(r));
+
+	/* Compute our exchange value in parallel with the client */
+	if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
+		goto out;
+
+	do {
+		debug("Wait SSH2_MSG_GSSAPI_INIT");
+		type = ssh_packet_read(ssh);
+		switch(type) {
+		case SSH2_MSG_KEXGSS_INIT:
+			if (dh_client_pub != NULL)
+				fatal("Received KEXGSS_INIT after initialising");
+			if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+			        &recv_tok)) != 0 ||
+			    (r = sshpkt_get_bignum2(ssh, &dh_client_pub)) != 0 ||
+			    (r = sshpkt_get_end(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+
+			/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
+			break;
+		case SSH2_MSG_KEXGSS_CONTINUE:
+			if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+			        &recv_tok)) != 0 ||
+			    (r = sshpkt_get_end(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+			break;
+		default:
+			sshpkt_disconnect(ssh,
+			    "Protocol error: didn't expect packet type %d",
+			    type);
+		}
+
+		maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
+		    &send_tok, &ret_flags));
+
+		gss_release_buffer(&min_status, &recv_tok);
+
+		if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
+			fatal("Zero length token output when incomplete");
+
+		if (dh_client_pub == NULL)
+			fatal("No client public key");
+
+		if (maj_status & GSS_S_CONTINUE_NEEDED) {
+			debug("Sending GSSAPI_CONTINUE");
+			if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+			    (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+			gss_release_buffer(&min_status, &send_tok);
+		}
+	} while (maj_status & GSS_S_CONTINUE_NEEDED);
+
+	if (GSS_ERROR(maj_status)) {
+		if (send_tok.length > 0) {
+			if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
+			    (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0)
+				fatal("sshpkt failed: %s", ssh_err(r));
+		}
+		fatal("accept_ctx died");
+	}
+
+	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
+		fatal("Mutual Authentication flag wasn't set");
+
+	if (!(ret_flags & GSS_C_INTEG_FLAG))
+		fatal("Integrity flag wasn't set");
+
+	/* calculate shared secret */
+	if ((shared_secret = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if ((r = kex_dh_compute_key(kex, dh_client_pub, shared_secret)) != 0)
+		goto out;
+
+	DH_get0_key(kex->dh, &pub_key, NULL);
+	DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
+	hashlen = sizeof(hash);
+	if ((r = kexgex_hash(
+	    kex->hash_alg,
+	    kex->client_version,
+	    kex->server_version,
+	    kex->peer,
+	    kex->my,
+	    empty,
+	    cmin, nbits, cmax,
+	    dh_p, dh_g,
+	    dh_client_pub,
+	    pub_key,
+	    sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
+	    hash, &hashlen)) != 0)
+		fatal("kexgex_hash failed: %s", ssh_err(r));
+
+	gssbuf.value = hash;
+	gssbuf.length = hashlen;
+
+	if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))))
+		fatal("Couldn't get MIC");
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 ||
+	    (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 ||
+	    (r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0)
+		fatal("sshpkt failed: %s", ssh_err(r));
+
+	if (send_tok.length != 0) {
+		if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */
+		    (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0)
+			fatal("sshpkt failed: %s", ssh_err(r));
+	} else {
+		if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */
+			fatal("sshpkt failed: %s", ssh_err(r));
+	}
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("sshpkt failed: %s", ssh_err(r));
+
+	gss_release_buffer(&min_status, &send_tok);
+	gss_release_buffer(&min_status, &msg_tok);
+
+	if (gss_kex_context == NULL)
+		gss_kex_context = ctxt;
+	else
+		ssh_gssapi_delete_ctx(&ctxt);
+
+	/* Finally derive the keys and send them */
+	if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
+		r = kex_send_newkeys(ssh);
+
+	/* If this was a rekey, then save out any delegated credentials we
+	 * just exchanged.  */
+	if (options.gss_store_rekey)
+		ssh_gssapi_rekey_creds();
+out:
+	sshbuf_free(empty);
+	explicit_bzero(hash, sizeof(hash));
+	DH_free(kex->dh);
+	kex->dh = NULL;
+	BN_clear_free(dh_client_pub);
+	sshbuf_free(shared_secret);
+	return r;
+}
+#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */
diff --git a/monitor.c b/monitor.c
index 2ce89fe90..ebf76c7f9 100644
--- a/monitor.c
+++ b/monitor.c
@@ -148,6 +148,8 @@ int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *);
 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *);
 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *);
 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *);
+int mm_answer_gss_sign(struct ssh *, int, struct sshbuf *);
+int mm_answer_gss_updatecreds(struct ssh *, int, struct sshbuf *);
 #endif
 
 #ifdef SSH_AUDIT_EVENTS
@@ -220,11 +222,18 @@ struct mon_table mon_dispatch_proto20[] = {
     {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
     {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
     {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
+    {MONITOR_REQ_GSSSIGN, MON_ONCE, mm_answer_gss_sign},
 #endif
     {0, 0, NULL}
 };
 
 struct mon_table mon_dispatch_postauth20[] = {
+#ifdef GSSAPI
+    {MONITOR_REQ_GSSSETUP, 0, mm_answer_gss_setup_ctx},
+    {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
+    {MONITOR_REQ_GSSSIGN, 0, mm_answer_gss_sign},
+    {MONITOR_REQ_GSSUPCREDS, 0, mm_answer_gss_updatecreds},
+#endif
 #ifdef WITH_OPENSSL
     {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
 #endif
@@ -293,6 +302,10 @@ monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
 	/* Permit requests for moduli and signatures */
 	monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
 	monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
+#ifdef GSSAPI
+	/* and for the GSSAPI key exchange */
+	monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1);
+#endif
 
 	/* The first few requests do not require asynchronous access */
 	while (!authenticated) {
@@ -406,6 +419,10 @@ monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
 	monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
 	monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
 	monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
+#ifdef GSSAPI
+	/* and for the GSSAPI key exchange */
+	monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1);
+#endif
 
 	if (auth_opts->permit_pty_flag) {
 		monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
@@ -1713,6 +1730,17 @@ monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
 # ifdef OPENSSL_HAS_ECC
 		kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
 # endif
+# ifdef GSSAPI
+		if (options.gss_keyex) {
+			kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
+			kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
+			kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server;
+			kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server;
+			kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server;
+			kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server;
+			kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server;
+		}
+# endif
 #endif /* WITH_OPENSSL */
 		kex->kex[KEX_C25519_SHA256] = kex_gen_server;
 		kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server;
@@ -1806,8 +1834,8 @@ mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
 	u_char *p;
 	int r;
 
-	if (!options.gss_authentication)
-		fatal("%s: GSSAPI authentication not enabled", __func__);
+	if (!options.gss_authentication && !options.gss_keyex)
+		fatal("%s: GSSAPI not enabled", __func__);
 
 	if ((r = sshbuf_get_string(m, &p, &len)) != 0)
 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
@@ -1839,8 +1867,8 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
 	OM_uint32 flags = 0; /* GSI needs this */
 	int r;
 
-	if (!options.gss_authentication)
-		fatal("%s: GSSAPI authentication not enabled", __func__);
+	if (!options.gss_authentication && !options.gss_keyex)
+		fatal("%s: GSSAPI not enabled", __func__);
 
 	if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
@@ -1860,6 +1888,7 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_GSSSIGN, 1);
 	}
 	return (0);
 }
@@ -1871,8 +1900,8 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
 	OM_uint32 ret;
 	int r;
 
-	if (!options.gss_authentication)
-		fatal("%s: GSSAPI authentication not enabled", __func__);
+	if (!options.gss_authentication && !options.gss_keyex)
+		fatal("%s: GSSAPI not enabled", __func__);
 
 	if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
 	    (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
@@ -1898,13 +1927,17 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
 int
 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
 {
-	int r, authenticated;
+	int r, authenticated, kex;
 	const char *displayname;
 
-	if (!options.gss_authentication)
-		fatal("%s: GSSAPI authentication not enabled", __func__);
+	if (!options.gss_authentication && !options.gss_keyex)
+		fatal("%s: GSSAPI not enabled", __func__);
 
-	authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
+	if ((r = sshbuf_get_u32(m, &kex)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	authenticated = authctxt->valid &&
+	    ssh_gssapi_userok(authctxt->user, authctxt->pw, kex);
 
 	sshbuf_reset(m);
 	if ((r = sshbuf_put_u32(m, authenticated)) != 0)
@@ -1913,7 +1946,11 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
 	debug3("%s: sending result %d", __func__, authenticated);
 	mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
 
-	auth_method = "gssapi-with-mic";
+	if (kex) {
+		auth_method = "gssapi-keyex";
+	} else {
+		auth_method = "gssapi-with-mic";
+	}
 
 	if ((displayname = ssh_gssapi_displayname()) != NULL)
 		auth2_record_info(authctxt, "%s", displayname);
@@ -1921,5 +1958,85 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
 	/* Monitor loop will terminate if authenticated */
 	return (authenticated);
 }
+
+int
+mm_answer_gss_sign(struct ssh *ssh, int socket, struct sshbuf *m)
+{
+	gss_buffer_desc data;
+	gss_buffer_desc hash = GSS_C_EMPTY_BUFFER;
+	OM_uint32 major, minor;
+	size_t len;
+	u_char *p = NULL;
+	int r;
+
+	if (!options.gss_authentication && !options.gss_keyex)
+		fatal("%s: GSSAPI not enabled", __func__);
+
+	if ((r = sshbuf_get_string(m, &p, &len)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	data.value = p;
+	data.length = len;
+	/* Lengths of SHA-1, SHA-256 and SHA-512 hashes that are used */
+	if (data.length != 20 && data.length != 32 && data.length != 64)
+		fatal("%s: data length incorrect: %d", __func__,
+		    (int) data.length);
+
+	/* Save the session ID on the first time around */
+	if (session_id2_len == 0) {
+		session_id2_len = data.length;
+		session_id2 = xmalloc(session_id2_len);
+		memcpy(session_id2, data.value, session_id2_len);
+	}
+	major = ssh_gssapi_sign(gsscontext, &data, &hash);
+
+	free(data.value);
+
+	sshbuf_reset(m);
+
+	if ((r = sshbuf_put_u32(m, major)) != 0 ||
+	    (r = sshbuf_put_string(m, hash.value, hash.length)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	mm_request_send(socket, MONITOR_ANS_GSSSIGN, m);
+
+	gss_release_buffer(&minor, &hash);
+
+	/* Turn on getpwnam permissions */
+	monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
+
+	/* And credential updating, for when rekeying */
+	monitor_permit(mon_dispatch, MONITOR_REQ_GSSUPCREDS, 1);
+
+	return (0);
+}
+
+int
+mm_answer_gss_updatecreds(struct ssh *ssh, int socket, struct sshbuf *m) {
+	ssh_gssapi_ccache store;
+	int r, ok;
+
+	if (!options.gss_authentication && !options.gss_keyex)
+		fatal("%s: GSSAPI not enabled", __func__);
+
+	if ((r = sshbuf_get_string(m, (u_char **)&store.filename, NULL)) != 0 ||
+	    (r = sshbuf_get_string(m, (u_char **)&store.envvar, NULL)) != 0 ||
+	    (r = sshbuf_get_string(m, (u_char **)&store.envval, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	ok = ssh_gssapi_update_creds(&store);
+
+	free(store.filename);
+	free(store.envvar);
+	free(store.envval);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, ok)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	mm_request_send(socket, MONITOR_ANS_GSSUPCREDS, m);
+
+	return(0);
+}
+
 #endif /* GSSAPI */
 
diff --git a/monitor.h b/monitor.h
index 683e5e071..2b1a2d590 100644
--- a/monitor.h
+++ b/monitor.h
@@ -63,6 +63,8 @@ enum monitor_reqtype {
 	MONITOR_REQ_PAM_FREE_CTX = 110, MONITOR_ANS_PAM_FREE_CTX = 111,
 	MONITOR_REQ_AUDIT_EVENT = 112, MONITOR_REQ_AUDIT_COMMAND = 113,
 
+	MONITOR_REQ_GSSSIGN = 150, MONITOR_ANS_GSSSIGN = 151,
+	MONITOR_REQ_GSSUPCREDS = 152, MONITOR_ANS_GSSUPCREDS = 153,
 };
 
 struct ssh;
diff --git a/monitor_wrap.c b/monitor_wrap.c
index 001a8fa1c..6edb509a3 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -993,13 +993,15 @@ mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
 }
 
 int
-mm_ssh_gssapi_userok(char *user)
+mm_ssh_gssapi_userok(char *user, struct passwd *pw, int kex)
 {
 	struct sshbuf *m;
 	int r, authenticated = 0;
 
 	if ((m = sshbuf_new()) == NULL)
 		fatal("%s: sshbuf_new failed", __func__);
+	if ((r = sshbuf_put_u32(m, kex)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
 	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m);
 	mm_request_receive_expect(pmonitor->m_recvfd,
@@ -1012,4 +1014,57 @@ mm_ssh_gssapi_userok(char *user)
 	debug3("%s: user %sauthenticated",__func__, authenticated ? "" : "not ");
 	return (authenticated);
 }
+
+OM_uint32
+mm_ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_desc *data, gss_buffer_desc *hash)
+{
+	struct sshbuf *m;
+	OM_uint32 major;
+	int r;
+
+	if ((m = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	if ((r = sshbuf_put_string(m, data->value, data->length)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSIGN, m);
+	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSIGN, m);
+
+	if ((r = sshbuf_get_u32(m, &major)) != 0 ||
+	    (r = ssh_gssapi_get_buffer_desc(m, hash)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	sshbuf_free(m);
+
+	return (major);
+}
+
+int
+mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *store)
+{
+	struct sshbuf *m;
+	int r, ok;
+
+	if ((m = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+
+	if ((r = sshbuf_put_cstring(m,
+	    store->filename ? store->filename : "")) != 0 ||
+	    (r = sshbuf_put_cstring(m,
+	    store->envvar ? store->envvar : "")) != 0 ||
+	    (r = sshbuf_put_cstring(m,
+	    store->envval ? store->envval : "")) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUPCREDS, m);
+	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSUPCREDS, m);
+
+	if ((r = sshbuf_get_u32(m, &ok)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	sshbuf_free(m);
+
+	return (ok);
+}
+
 #endif /* GSSAPI */
diff --git a/monitor_wrap.h b/monitor_wrap.h
index 23ab096aa..485590c18 100644
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@@ -64,8 +64,10 @@ int mm_sshkey_verify(const struct sshkey *, const u_char *, size_t,
 OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **, gss_OID);
 OM_uint32 mm_ssh_gssapi_accept_ctx(Gssctxt *,
    gss_buffer_desc *, gss_buffer_desc *, OM_uint32 *);
-int mm_ssh_gssapi_userok(char *user);
+int mm_ssh_gssapi_userok(char *user, struct passwd *, int kex);
 OM_uint32 mm_ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
+OM_uint32 mm_ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t);
+int mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *);
 #endif
 
 #ifdef USE_PAM
diff --git a/readconf.c b/readconf.c
index f3cac6b3a..da8022dd0 100644
--- a/readconf.c
+++ b/readconf.c
@@ -67,6 +67,7 @@
 #include "uidswap.h"
 #include "myproposal.h"
 #include "digest.h"
+#include "ssh-gss.h"
 
 /* Format of the configuration file:
 
@@ -160,6 +161,8 @@ typedef enum {
 	oClearAllForwardings, oNoHostAuthenticationForLocalhost,
 	oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout,
 	oAddressFamily, oGssAuthentication, oGssDelegateCreds,
+	oGssTrustDns, oGssKeyEx, oGssClientIdentity, oGssRenewalRekey,
+	oGssServerIdentity, oGssKexAlgorithms,
 	oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly,
 	oSendEnv, oSetEnv, oControlPath, oControlMaster, oControlPersist,
 	oHashKnownHosts,
@@ -204,10 +207,22 @@ static struct {
 	/* Sometimes-unsupported options */
 #if defined(GSSAPI)
 	{ "gssapiauthentication", oGssAuthentication },
+	{ "gssapikeyexchange", oGssKeyEx },
 	{ "gssapidelegatecredentials", oGssDelegateCreds },
+	{ "gssapitrustdns", oGssTrustDns },
+	{ "gssapiclientidentity", oGssClientIdentity },
+	{ "gssapiserveridentity", oGssServerIdentity },
+	{ "gssapirenewalforcesrekey", oGssRenewalRekey },
+	{ "gssapikexalgorithms", oGssKexAlgorithms },
 # else
 	{ "gssapiauthentication", oUnsupported },
+	{ "gssapikeyexchange", oUnsupported },
 	{ "gssapidelegatecredentials", oUnsupported },
+	{ "gssapitrustdns", oUnsupported },
+	{ "gssapiclientidentity", oUnsupported },
+	{ "gssapiserveridentity", oUnsupported },
+	{ "gssapirenewalforcesrekey", oUnsupported },
+	{ "gssapikexalgorithms", oUnsupported },
 #endif
 #ifdef ENABLE_PKCS11
 	{ "pkcs11provider", oPKCS11Provider },
@@ -1029,10 +1044,42 @@ parse_time:
 		intptr = &options->gss_authentication;
 		goto parse_flag;
 
+	case oGssKeyEx:
+		intptr = &options->gss_keyex;
+		goto parse_flag;
+
 	case oGssDelegateCreds:
 		intptr = &options->gss_deleg_creds;
 		goto parse_flag;
 
+	case oGssTrustDns:
+		intptr = &options->gss_trust_dns;
+		goto parse_flag;
+
+	case oGssClientIdentity:
+		charptr = &options->gss_client_identity;
+		goto parse_string;
+
+	case oGssServerIdentity:
+		charptr = &options->gss_server_identity;
+		goto parse_string;
+
+	case oGssRenewalRekey:
+		intptr = &options->gss_renewal_rekey;
+		goto parse_flag;
+
+	case oGssKexAlgorithms:
+		arg = strdelim(&s);
+		if (!arg || *arg == '\0')
+			fatal("%.200s line %d: Missing argument.",
+			    filename, linenum);
+		if (!kex_gss_names_valid(arg))
+			fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.",
+			    filename, linenum, arg ? arg : "<NONE>");
+		if (*activep && options->gss_kex_algorithms == NULL)
+			options->gss_kex_algorithms = xstrdup(arg);
+		break;
+
 	case oBatchMode:
 		intptr = &options->batch_mode;
 		goto parse_flag;
@@ -1911,7 +1958,13 @@ initialize_options(Options * options)
 	options->pubkey_authentication = -1;
 	options->challenge_response_authentication = -1;
 	options->gss_authentication = -1;
+	options->gss_keyex = -1;
 	options->gss_deleg_creds = -1;
+	options->gss_trust_dns = -1;
+	options->gss_renewal_rekey = -1;
+	options->gss_client_identity = NULL;
+	options->gss_server_identity = NULL;
+	options->gss_kex_algorithms = NULL;
 	options->password_authentication = -1;
 	options->kbd_interactive_authentication = -1;
 	options->kbd_interactive_devices = NULL;
@@ -2059,8 +2112,18 @@ fill_default_options(Options * options)
 		options->challenge_response_authentication = 1;
 	if (options->gss_authentication == -1)
 		options->gss_authentication = 0;
+	if (options->gss_keyex == -1)
+		options->gss_keyex = 0;
 	if (options->gss_deleg_creds == -1)
 		options->gss_deleg_creds = 0;
+	if (options->gss_trust_dns == -1)
+		options->gss_trust_dns = 0;
+	if (options->gss_renewal_rekey == -1)
+		options->gss_renewal_rekey = 0;
+#ifdef GSSAPI
+	if (options->gss_kex_algorithms == NULL)
+		options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX);
+#endif
 	if (options->password_authentication == -1)
 		options->password_authentication = 1;
 	if (options->kbd_interactive_authentication == -1)
@@ -2702,7 +2765,14 @@ dump_client_config(Options *o, const char *host)
 	dump_cfg_fmtint(oGatewayPorts, o->fwd_opts.gateway_ports);
 #ifdef GSSAPI
 	dump_cfg_fmtint(oGssAuthentication, o->gss_authentication);
+	dump_cfg_fmtint(oGssKeyEx, o->gss_keyex);
 	dump_cfg_fmtint(oGssDelegateCreds, o->gss_deleg_creds);
+	dump_cfg_fmtint(oGssTrustDns, o->gss_trust_dns);
+	dump_cfg_fmtint(oGssRenewalRekey, o->gss_renewal_rekey);
+	dump_cfg_string(oGssClientIdentity, o->gss_client_identity);
+	dump_cfg_string(oGssServerIdentity, o->gss_server_identity);
+	dump_cfg_string(oGssKexAlgorithms, o->gss_kex_algorithms ?
+	    o->gss_kex_algorithms : GSS_KEX_DEFAULT_KEX);
 #endif /* GSSAPI */
 	dump_cfg_fmtint(oHashKnownHosts, o->hash_known_hosts);
 	dump_cfg_fmtint(oHostbasedAuthentication, o->hostbased_authentication);
diff --git a/readconf.h b/readconf.h
index feedb3d20..a8a8870d7 100644
--- a/readconf.h
+++ b/readconf.h
@@ -41,7 +41,13 @@ typedef struct {
 	int     challenge_response_authentication;
 					/* Try S/Key or TIS, authentication. */
 	int     gss_authentication;	/* Try GSS authentication */
+	int     gss_keyex;		/* Try GSS key exchange */
 	int     gss_deleg_creds;	/* Delegate GSS credentials */
+	int	gss_trust_dns;		/* Trust DNS for GSS canonicalization */
+	int	gss_renewal_rekey;	/* Credential renewal forces rekey */
+	char    *gss_client_identity;   /* Principal to initiate GSSAPI with */
+	char    *gss_server_identity;   /* GSSAPI target principal */
+	char    *gss_kex_algorithms;	/* GSSAPI kex methods to be offered by client. */
 	int     password_authentication;	/* Try password
 						 * authentication. */
 	int     kbd_interactive_authentication; /* Try keyboard-interactive auth. */
diff --git a/servconf.c b/servconf.c
index 70f5f73f0..191575a16 100644
--- a/servconf.c
+++ b/servconf.c
@@ -69,6 +69,7 @@
 #include "auth.h"
 #include "myproposal.h"
 #include "digest.h"
+#include "ssh-gss.h"
 
 static void add_listen_addr(ServerOptions *, const char *,
     const char *, int);
@@ -133,8 +134,11 @@ initialize_server_options(ServerOptions *options)
 	options->kerberos_ticket_cleanup = -1;
 	options->kerberos_get_afs_token = -1;
 	options->gss_authentication=-1;
+	options->gss_keyex = -1;
 	options->gss_cleanup_creds = -1;
 	options->gss_strict_acceptor = -1;
+	options->gss_store_rekey = -1;
+	options->gss_kex_algorithms = NULL;
 	options->password_authentication = -1;
 	options->kbd_interactive_authentication = -1;
 	options->challenge_response_authentication = -1;
@@ -375,10 +379,18 @@ fill_default_server_options(ServerOptions *options)
 		options->kerberos_get_afs_token = 0;
 	if (options->gss_authentication == -1)
 		options->gss_authentication = 0;
+	if (options->gss_keyex == -1)
+		options->gss_keyex = 0;
 	if (options->gss_cleanup_creds == -1)
 		options->gss_cleanup_creds = 1;
 	if (options->gss_strict_acceptor == -1)
 		options->gss_strict_acceptor = 1;
+	if (options->gss_store_rekey == -1)
+		options->gss_store_rekey = 0;
+#ifdef GSSAPI
+	if (options->gss_kex_algorithms == NULL)
+		options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX);
+#endif
 	if (options->password_authentication == -1)
 		options->password_authentication = 1;
 	if (options->kbd_interactive_authentication == -1)
@@ -531,6 +543,7 @@ typedef enum {
 	sHostKeyAlgorithms,
 	sClientAliveInterval, sClientAliveCountMax, sAuthorizedKeysFile,
 	sGssAuthentication, sGssCleanupCreds, sGssStrictAcceptor,
+	sGssKeyEx, sGssKexAlgorithms, sGssStoreRekey,
 	sAcceptEnv, sSetEnv, sPermitTunnel,
 	sMatch, sPermitOpen, sPermitListen, sForceCommand, sChrootDirectory,
 	sUsePrivilegeSeparation, sAllowAgentForwarding,
@@ -607,12 +620,22 @@ static struct {
 #ifdef GSSAPI
 	{ "gssapiauthentication", sGssAuthentication, SSHCFG_ALL },
 	{ "gssapicleanupcredentials", sGssCleanupCreds, SSHCFG_GLOBAL },
+	{ "gssapicleanupcreds", sGssCleanupCreds, SSHCFG_GLOBAL },
 	{ "gssapistrictacceptorcheck", sGssStrictAcceptor, SSHCFG_GLOBAL },
+	{ "gssapikeyexchange", sGssKeyEx, SSHCFG_GLOBAL },
+	{ "gssapistorecredentialsonrekey", sGssStoreRekey, SSHCFG_GLOBAL },
+	{ "gssapikexalgorithms", sGssKexAlgorithms, SSHCFG_GLOBAL },
 #else
 	{ "gssapiauthentication", sUnsupported, SSHCFG_ALL },
 	{ "gssapicleanupcredentials", sUnsupported, SSHCFG_GLOBAL },
+	{ "gssapicleanupcreds", sUnsupported, SSHCFG_GLOBAL },
 	{ "gssapistrictacceptorcheck", sUnsupported, SSHCFG_GLOBAL },
+	{ "gssapikeyexchange", sUnsupported, SSHCFG_GLOBAL },
+	{ "gssapistorecredentialsonrekey", sUnsupported, SSHCFG_GLOBAL },
+	{ "gssapikexalgorithms", sUnsupported, SSHCFG_GLOBAL },
 #endif
+	{ "gssusesessionccache", sUnsupported, SSHCFG_GLOBAL },
+	{ "gssapiusesessioncredcache", sUnsupported, SSHCFG_GLOBAL },
 	{ "passwordauthentication", sPasswordAuthentication, SSHCFG_ALL },
 	{ "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL },
 	{ "challengeresponseauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL },
@@ -1548,6 +1571,10 @@ process_server_config_line_depth(ServerOptions *options, char *line,
 		intptr = &options->gss_authentication;
 		goto parse_flag;
 
+	case sGssKeyEx:
+		intptr = &options->gss_keyex;
+		goto parse_flag;
+
 	case sGssCleanupCreds:
 		intptr = &options->gss_cleanup_creds;
 		goto parse_flag;
@@ -1556,6 +1583,22 @@ process_server_config_line_depth(ServerOptions *options, char *line,
 		intptr = &options->gss_strict_acceptor;
 		goto parse_flag;
 
+	case sGssStoreRekey:
+		intptr = &options->gss_store_rekey;
+		goto parse_flag;
+
+	case sGssKexAlgorithms:
+		arg = strdelim(&cp);
+		if (!arg || *arg == '\0')
+			fatal("%.200s line %d: Missing argument.",
+			    filename, linenum);
+		if (!kex_gss_names_valid(arg))
+			fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.",
+			    filename, linenum, arg ? arg : "<NONE>");
+		if (*activep && options->gss_kex_algorithms == NULL)
+			options->gss_kex_algorithms = xstrdup(arg);
+		break;
+
 	case sPasswordAuthentication:
 		intptr = &options->password_authentication;
 		goto parse_flag;
@@ -2777,6 +2820,10 @@ dump_config(ServerOptions *o)
 #ifdef GSSAPI
 	dump_cfg_fmtint(sGssAuthentication, o->gss_authentication);
 	dump_cfg_fmtint(sGssCleanupCreds, o->gss_cleanup_creds);
+	dump_cfg_fmtint(sGssKeyEx, o->gss_keyex);
+	dump_cfg_fmtint(sGssStrictAcceptor, o->gss_strict_acceptor);
+	dump_cfg_fmtint(sGssStoreRekey, o->gss_store_rekey);
+	dump_cfg_string(sGssKexAlgorithms, o->gss_kex_algorithms);
 #endif
 	dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication);
 	dump_cfg_fmtint(sKbdInteractiveAuthentication,
diff --git a/servconf.h b/servconf.h
index 4202a2d02..3f47ea25e 100644
--- a/servconf.h
+++ b/servconf.h
@@ -132,8 +132,11 @@ typedef struct {
 	int     kerberos_get_afs_token;		/* If true, try to get AFS token if
 						 * authenticated with Kerberos. */
 	int     gss_authentication;	/* If true, permit GSSAPI authentication */
+	int     gss_keyex;		/* If true, permit GSSAPI key exchange */
 	int     gss_cleanup_creds;	/* If true, destroy cred cache on logout */
 	int     gss_strict_acceptor;	/* If true, restrict the GSSAPI acceptor name */
+	int 	gss_store_rekey;
+	char   *gss_kex_algorithms;	/* GSSAPI kex methods to be offered by client. */
 	int     password_authentication;	/* If true, permit password
 						 * authentication. */
 	int     kbd_interactive_authentication;	/* If true, permit */
diff --git a/session.c b/session.c
index 8c0e54f79..06a33442a 100644
--- a/session.c
+++ b/session.c
@@ -2678,13 +2678,19 @@ do_cleanup(struct ssh *ssh, Authctxt *authctxt)
 
 #ifdef KRB5
 	if (options.kerberos_ticket_cleanup &&
-	    authctxt->krb5_ctx)
+	    authctxt->krb5_ctx) {
+		temporarily_use_uid(authctxt->pw);
 		krb5_cleanup_proc(authctxt);
+		restore_uid();
+	}
 #endif
 
 #ifdef GSSAPI
-	if (options.gss_cleanup_creds)
+	if (options.gss_cleanup_creds) {
+		temporarily_use_uid(authctxt->pw);
 		ssh_gssapi_cleanup_creds();
+		restore_uid();
+	}
 #endif
 
 	/* remove agent socket */
diff --git a/ssh-gss.h b/ssh-gss.h
index 36180d07a..70dd36658 100644
--- a/ssh-gss.h
+++ b/ssh-gss.h
@@ -1,6 +1,6 @@
 /* $OpenBSD: ssh-gss.h,v 1.14 2018/07/10 09:13:30 djm Exp $ */
 /*
- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -61,10 +61,30 @@
 
 #define SSH_GSS_OIDTYPE 0x06
 
+#define SSH2_MSG_KEXGSS_INIT                            30
+#define SSH2_MSG_KEXGSS_CONTINUE                        31
+#define SSH2_MSG_KEXGSS_COMPLETE                        32
+#define SSH2_MSG_KEXGSS_HOSTKEY                         33
+#define SSH2_MSG_KEXGSS_ERROR                           34
+#define SSH2_MSG_KEXGSS_GROUPREQ			40
+#define SSH2_MSG_KEXGSS_GROUP				41
+#define KEX_GSS_GRP1_SHA1_ID				"gss-group1-sha1-"
+#define KEX_GSS_GRP14_SHA1_ID				"gss-group14-sha1-"
+#define KEX_GSS_GRP14_SHA256_ID			"gss-group14-sha256-"
+#define KEX_GSS_GRP16_SHA512_ID			"gss-group16-sha512-"
+#define KEX_GSS_GEX_SHA1_ID				"gss-gex-sha1-"
+#define KEX_GSS_NISTP256_SHA256_ID			"gss-nistp256-sha256-"
+#define KEX_GSS_C25519_SHA256_ID			"gss-curve25519-sha256-"
+
+#define        GSS_KEX_DEFAULT_KEX \
+	KEX_GSS_GEX_SHA1_ID "," \
+	KEX_GSS_GRP14_SHA1_ID
+
 typedef struct {
 	char *filename;
 	char *envvar;
 	char *envval;
+	struct passwd *owner;
 	void *data;
 } ssh_gssapi_ccache;
 
@@ -72,8 +92,11 @@ typedef struct {
 	gss_buffer_desc displayname;
 	gss_buffer_desc exportedname;
 	gss_cred_id_t creds;
+	gss_name_t name;
 	struct ssh_gssapi_mech_struct *mech;
 	ssh_gssapi_ccache store;
+	int used;
+	int updated;
 } ssh_gssapi_client;
 
 typedef struct ssh_gssapi_mech_struct {
@@ -84,6 +107,7 @@ typedef struct ssh_gssapi_mech_struct {
 	int (*userok) (ssh_gssapi_client *, char *);
 	int (*localname) (ssh_gssapi_client *, char **);
 	void (*storecreds) (ssh_gssapi_client *);
+	int (*updatecreds) (ssh_gssapi_ccache *, ssh_gssapi_client *);
 } ssh_gssapi_mech;
 
 typedef struct {
@@ -94,10 +118,11 @@ typedef struct {
 	gss_OID		oid; /* client */
 	gss_cred_id_t	creds; /* server */
 	gss_name_t	client; /* server */
-	gss_cred_id_t	client_creds; /* server */
+	gss_cred_id_t	client_creds; /* both */
 } Gssctxt;
 
 extern ssh_gssapi_mech *supported_mechs[];
+extern Gssctxt *gss_kex_context;
 
 int  ssh_gssapi_check_oid(Gssctxt *, void *, size_t);
 void ssh_gssapi_set_oid_data(Gssctxt *, void *, size_t);
@@ -109,6 +134,7 @@ OM_uint32 ssh_gssapi_test_oid_supported(OM_uint32 *, gss_OID, int *);
 
 struct sshbuf;
 int ssh_gssapi_get_buffer_desc(struct sshbuf *, gss_buffer_desc *);
+int ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *, gss_buffer_desc *);
 
 OM_uint32 ssh_gssapi_import_name(Gssctxt *, const char *);
 OM_uint32 ssh_gssapi_init_ctx(Gssctxt *, int,
@@ -123,17 +149,33 @@ void ssh_gssapi_delete_ctx(Gssctxt **);
 OM_uint32 ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t);
 void ssh_gssapi_buildmic(struct sshbuf *, const char *,
     const char *, const char *);
-int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *);
+int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *, const char *);
+OM_uint32 ssh_gssapi_client_identity(Gssctxt *, const char *);
+int ssh_gssapi_credentials_updated(Gssctxt *);
 
 /* In the server */
+typedef int ssh_gssapi_check_fn(Gssctxt **, gss_OID, const char *,
+    const char *);
+char *ssh_gssapi_client_mechanisms(const char *, const char *, const char *);
+char *ssh_gssapi_kex_mechs(gss_OID_set, ssh_gssapi_check_fn *, const char *,
+    const char *, const char *);
+gss_OID ssh_gssapi_id_kex(Gssctxt *, char *, int);
+int ssh_gssapi_server_check_mech(Gssctxt **,gss_OID, const char *,
+    const char *);
 OM_uint32 ssh_gssapi_server_ctx(Gssctxt **, gss_OID);
-int ssh_gssapi_userok(char *name);
+int ssh_gssapi_userok(char *name, struct passwd *, int kex);
 OM_uint32 ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
 void ssh_gssapi_do_child(char ***, u_int *);
 void ssh_gssapi_cleanup_creds(void);
 void ssh_gssapi_storecreds(void);
 const char *ssh_gssapi_displayname(void);
 
+char *ssh_gssapi_server_mechanisms(void);
+int ssh_gssapi_oid_table_ok(void);
+
+int ssh_gssapi_update_creds(ssh_gssapi_ccache *store);
+void ssh_gssapi_rekey_creds(void);
+
 #endif /* GSSAPI */
 
 #endif /* _SSH_GSS_H */
diff --git a/ssh.1 b/ssh.1
index 60de6087a..db5c65bc7 100644
--- a/ssh.1
+++ b/ssh.1
@@ -503,7 +503,13 @@ For full details of the options listed below, and their possible values, see
 .It GatewayPorts
 .It GlobalKnownHostsFile
 .It GSSAPIAuthentication
+.It GSSAPIKeyExchange
+.It GSSAPIClientIdentity
 .It GSSAPIDelegateCredentials
+.It GSSAPIKexAlgorithms
+.It GSSAPIRenewalForcesRekey
+.It GSSAPIServerIdentity
+.It GSSAPITrustDns
 .It HashKnownHosts
 .It Host
 .It HostbasedAuthentication
@@ -579,6 +585,8 @@ flag),
 (supported message integrity codes),
 .Ar kex
 (key exchange algorithms),
+.Ar kex-gss
+(GSSAPI key exchange algorithms),
 .Ar key
 (key types),
 .Ar key-cert
diff --git a/ssh.c b/ssh.c
index 15aee569e..110cf9c19 100644
--- a/ssh.c
+++ b/ssh.c
@@ -747,6 +747,8 @@ main(int ac, char **av)
 			else if (strcmp(optarg, "kex") == 0 ||
 			    strcasecmp(optarg, "KexAlgorithms") == 0)
 				cp = kex_alg_list('\n');
+			else if (strcmp(optarg, "kex-gss") == 0)
+				cp = kex_gss_alg_list('\n');
 			else if (strcmp(optarg, "key") == 0)
 				cp = sshkey_alg_list(0, 0, 0, '\n');
 			else if (strcmp(optarg, "key-cert") == 0)
@@ -772,8 +774,8 @@ main(int ac, char **av)
 			} else if (strcmp(optarg, "help") == 0) {
 				cp = xstrdup(
 				    "cipher\ncipher-auth\ncompression\nkex\n"
-				    "key\nkey-cert\nkey-plain\nkey-sig\nmac\n"
-				    "protocol-version\nsig");
+				    "kex-gss\nkey\nkey-cert\nkey-plain\n"
+				    "key-sig\nmac\nprotocol-version\nsig");
 			}
 			if (cp == NULL)
 				fatal("Unsupported query \"%s\"", optarg);
diff --git a/ssh_config b/ssh_config
index 5e8ef548b..1ff999b68 100644
--- a/ssh_config
+++ b/ssh_config
@@ -24,6 +24,8 @@
 #   HostbasedAuthentication no
 #   GSSAPIAuthentication no
 #   GSSAPIDelegateCredentials no
+#   GSSAPIKeyExchange no
+#   GSSAPITrustDNS no
 #   BatchMode no
 #   CheckHostIP yes
 #   AddressFamily any
diff --git a/ssh_config.5 b/ssh_config.5
index 06a32d314..3f4906972 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -766,10 +766,67 @@ The default is
 Specifies whether user authentication based on GSSAPI is allowed.
 The default is
 .Cm no .
+.It Cm GSSAPIClientIdentity
+If set, specifies the GSSAPI client identity that ssh should use when
+connecting to the server. The default is unset, which means that the default
+identity will be used.
 .It Cm GSSAPIDelegateCredentials
 Forward (delegate) credentials to the server.
 The default is
 .Cm no .
+.It Cm GSSAPIKeyExchange
+Specifies whether key exchange based on GSSAPI may be used. When using
+GSSAPI key exchange the server need not have a host key.
+The default is
+.Dq no .
+.It Cm GSSAPIRenewalForcesRekey
+If set to
+.Dq yes
+then renewal of the client's GSSAPI credentials will force the rekeying of the
+ssh connection. With a compatible server, this will delegate the renewed
+credentials to a session on the server.
+.Pp
+Checks are made to ensure that credentials are only propagated when the new
+credentials match the old ones on the originating client and where the
+receiving server still has the old set in its cache.
+.Pp
+The default is
+.Dq no .
+.Pp
+For this to work
+.Cm GSSAPIKeyExchange
+needs to be enabled in the server and also used by the client.
+.It Cm GSSAPIServerIdentity
+If set, specifies the GSSAPI server identity that ssh should expect when
+connecting to the server. The default is unset, which means that the
+expected GSSAPI server identity will be determined from the target
+hostname.
+.It Cm GSSAPITrustDns
+Set to
+.Dq yes
+to indicate that the DNS is trusted to securely canonicalize
+the name of the host being connected to. If
+.Dq no ,
+the hostname entered on the
+command line will be passed untouched to the GSSAPI library.
+The default is
+.Dq no .
+.It Cm GSSAPIKexAlgorithms
+The list of key exchange algorithms that are offered for GSSAPI
+key exchange. Possible values are
+.Bd -literal -offset 3n
+gss-gex-sha1-,
+gss-group1-sha1-,
+gss-group14-sha1-,
+gss-group14-sha256-,
+gss-group16-sha512-,
+gss-nistp256-sha256-,
+gss-curve25519-sha256-
+.Ed
+.Pp
+The default is
+.Dq gss-gex-sha1-,gss-group14-sha1- .
+This option only applies to protocol version 2 connections using GSSAPI.
 .It Cm HashKnownHosts
 Indicates that
 .Xr ssh 1
diff --git a/sshconnect2.c b/sshconnect2.c
index af00fb30c..03bc87eb4 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -80,8 +80,6 @@
 #endif
 
 /* import */
-extern char *client_version_string;
-extern char *server_version_string;
 extern Options options;
 
 /*
@@ -163,6 +161,11 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
 	char *s, *all_key;
 	int r, use_known_hosts_order = 0;
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+	char *orig = NULL, *gss = NULL;
+	char *gss_host = NULL;
+#endif
+
 	xxx_host = host;
 	xxx_hostaddr = hostaddr;
 
@@ -206,6 +209,35 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
 		    compat_pkalg_proposal(options.hostkeyalgorithms);
 	}
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+	if (options.gss_keyex) {
+		/* Add the GSSAPI mechanisms currently supported on this
+		 * client to the key exchange algorithm proposal */
+		orig = myproposal[PROPOSAL_KEX_ALGS];
+
+		if (options.gss_server_identity)
+			gss_host = xstrdup(options.gss_server_identity);
+		else if (options.gss_trust_dns)
+			gss_host = remote_hostname(ssh);
+		else
+			gss_host = xstrdup(host);
+
+		gss = ssh_gssapi_client_mechanisms(gss_host,
+		    options.gss_client_identity, options.gss_kex_algorithms);
+		if (gss) {
+			debug("Offering GSSAPI proposal: %s", gss);
+			xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
+			    "%s,%s", gss, orig);
+
+			/* If we've got GSSAPI algorithms, then we also support the
+			 * 'null' hostkey, as a last resort */
+			orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
+			xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
+			    "%s,null", orig);
+		}
+	}
+#endif
+
 	if (options.rekey_limit || options.rekey_interval)
 		ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
 		    options.rekey_interval);
@@ -224,16 +256,46 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
 # ifdef OPENSSL_HAS_ECC
 	ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
 # endif
-#endif
+# ifdef GSSAPI
+	if (options.gss_keyex) {
+		ssh->kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
+		ssh->kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
+		ssh->kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_client;
+		ssh->kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_client;
+		ssh->kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_client;
+		ssh->kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_client;
+		ssh->kex->kex[KEX_GSS_C25519_SHA256] = kexgss_client;
+	}
+# endif
+#endif /* WITH_OPENSSL */
 	ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
 	ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client;
 	ssh->kex->verify_host_key=&verify_host_key_callback;
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+	if (options.gss_keyex) {
+		ssh->kex->gss_deleg_creds = options.gss_deleg_creds;
+		ssh->kex->gss_trust_dns = options.gss_trust_dns;
+		ssh->kex->gss_client = options.gss_client_identity;
+		ssh->kex->gss_host = gss_host;
+	}
+#endif
+
 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
 
 	/* remove ext-info from the KEX proposals for rekeying */
 	myproposal[PROPOSAL_KEX_ALGS] =
 	    compat_kex_proposal(options.kex_algorithms);
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+	/* repair myproposal after it was crumpled by the */
+	/* ext-info removal above */
+	if (gss) {
+		orig = myproposal[PROPOSAL_KEX_ALGS];
+		xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
+		    "%s,%s", gss, orig);
+		free(gss);
+	}
+#endif
 	if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0)
 		fatal("kex_prop2buf: %s", ssh_err(r));
 
@@ -330,6 +392,7 @@ static int input_gssapi_response(int type, u_int32_t, struct ssh *);
 static int input_gssapi_token(int type, u_int32_t, struct ssh *);
 static int input_gssapi_error(int, u_int32_t, struct ssh *);
 static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
+static int userauth_gsskeyex(struct ssh *);
 #endif
 
 void	userauth(struct ssh *, char *);
@@ -346,6 +409,11 @@ static char *authmethods_get(void);
 
 Authmethod authmethods[] = {
 #ifdef GSSAPI
+	{"gssapi-keyex",
+		userauth_gsskeyex,
+		NULL,
+		&options.gss_keyex,
+		NULL},
 	{"gssapi-with-mic",
 		userauth_gssapi,
 		userauth_gssapi_cleanup,
@@ -716,12 +784,25 @@ userauth_gssapi(struct ssh *ssh)
 	OM_uint32 min;
 	int r, ok = 0;
 	gss_OID mech = NULL;
+	char *gss_host;
+
+	if (options.gss_server_identity)
+		gss_host = xstrdup(options.gss_server_identity);
+	else if (options.gss_trust_dns)
+		gss_host = remote_hostname(ssh);
+	else
+		gss_host = xstrdup(authctxt->host);
 
 	/* Try one GSSAPI method at a time, rather than sending them all at
 	 * once. */
 
 	if (authctxt->gss_supported_mechs == NULL)
-		gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
+		if (GSS_ERROR(gss_indicate_mechs(&min,
+		    &authctxt->gss_supported_mechs))) {
+			authctxt->gss_supported_mechs = NULL;
+			free(gss_host);
+			return 0;
+		}
 
 	/* Check to see whether the mechanism is usable before we offer it */
 	while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
@@ -730,13 +811,15 @@ userauth_gssapi(struct ssh *ssh)
 		    elements[authctxt->mech_tried];
 		/* My DER encoding requires length<128 */
 		if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
-		    mech, authctxt->host)) {
+		    mech, gss_host, options.gss_client_identity)) {
 			ok = 1; /* Mechanism works */
 		} else {
 			authctxt->mech_tried++;
 		}
 	}
 
+	free(gss_host);
+
 	if (!ok || mech == NULL)
 		return 0;
 
@@ -976,6 +1059,55 @@ input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
 	free(lang);
 	return r;
 }
+
+int
+userauth_gsskeyex(struct ssh *ssh)
+{
+	struct sshbuf *b = NULL;
+	Authctxt *authctxt = ssh->authctxt;
+	gss_buffer_desc gssbuf;
+	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
+	OM_uint32 ms;
+	int r;
+
+	static int attempt = 0;
+	if (attempt++ >= 1)
+		return (0);
+
+	if (gss_kex_context == NULL) {
+		debug("No valid Key exchange context");
+		return (0);
+	}
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+
+	ssh_gssapi_buildmic(b, authctxt->server_user, authctxt->service,
+	    "gssapi-keyex");
+
+	if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
+		fatal("%s: sshbuf_mutable_ptr failed", __func__);
+	gssbuf.length = sshbuf_len(b);
+
+	if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
+		sshbuf_free(b);
+		return (0);
+	}
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_string(ssh, mic.value, mic.length)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+
+	sshbuf_free(b);
+	gss_release_buffer(&ms, &mic);
+
+	return (1);
+}
+
 #endif /* GSSAPI */
 
 static int
diff --git a/sshd.c b/sshd.c
index 60b2aaf73..d92f03aaf 100644
--- a/sshd.c
+++ b/sshd.c
@@ -817,8 +817,8 @@ notify_hostkeys(struct ssh *ssh)
 	}
 	debug3("%s: sent %u hostkeys", __func__, nkeys);
 	if (nkeys == 0)
-		fatal("%s: no hostkeys", __func__);
-	if ((r = sshpkt_send(ssh)) != 0)
+		debug3("%s: no hostkeys", __func__);
+	else if ((r = sshpkt_send(ssh)) != 0)
 		sshpkt_fatal(ssh, r, "%s: send", __func__);
 	sshbuf_free(buf);
 }
@@ -1852,7 +1852,8 @@ main(int ac, char **av)
 		free(fp);
 	}
 	accumulate_host_timing_secret(cfg, NULL);
-	if (!sensitive_data.have_ssh2_key) {
+	/* The GSSAPI key exchange can run without a host key */
+	if (!sensitive_data.have_ssh2_key && !options.gss_keyex) {
 		logit("sshd: no hostkeys available -- exiting.");
 		exit(1);
 	}
@@ -2347,6 +2348,48 @@ do_ssh2_kex(struct ssh *ssh)
 	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
 	    list_hostkey_types());
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+	{
+	char *orig;
+	char *gss = NULL;
+	char *newstr = NULL;
+	orig = myproposal[PROPOSAL_KEX_ALGS];
+
+	/*
+	 * If we don't have a host key, then there's no point advertising
+	 * the other key exchange algorithms
+	 */
+
+	if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
+		orig = NULL;
+
+	if (options.gss_keyex)
+		gss = ssh_gssapi_server_mechanisms();
+	else
+		gss = NULL;
+
+	if (gss && orig)
+		xasprintf(&newstr, "%s,%s", gss, orig);
+	else if (gss)
+		newstr = gss;
+	else if (orig)
+		newstr = orig;
+
+	/*
+	 * If we've got GSSAPI mechanisms, then we've got the 'null' host
+	 * key alg, but we can't tell people about it unless its the only
+	 * host key algorithm we support
+	 */
+	if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
+		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
+
+	if (newstr)
+		myproposal[PROPOSAL_KEX_ALGS] = newstr;
+	else
+		fatal("No supported key exchange algorithms");
+	}
+#endif
+
 	/* start key exchange */
 	if ((r = kex_setup(ssh, myproposal)) != 0)
 		fatal("kex_setup: %s", ssh_err(r));
@@ -2362,7 +2405,18 @@ do_ssh2_kex(struct ssh *ssh)
 # ifdef OPENSSL_HAS_ECC
 	kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
 # endif
-#endif
+# ifdef GSSAPI
+	if (options.gss_keyex) {
+		kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
+		kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
+		kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server;
+		kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server;
+		kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server;
+		kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server;
+		kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server;
+	}
+# endif
+#endif /* WITH_OPENSSL */
 	kex->kex[KEX_C25519_SHA256] = kex_gen_server;
 	kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server;
 	kex->load_host_public_key=&get_hostkey_public_by_type;
diff --git a/sshd_config b/sshd_config
index 19b7c91a1..2c48105f8 100644
--- a/sshd_config
+++ b/sshd_config
@@ -69,6 +69,8 @@ AuthorizedKeysFile	.ssh/authorized_keys
 # GSSAPI options
 #GSSAPIAuthentication no
 #GSSAPICleanupCredentials yes
+#GSSAPIStrictAcceptorCheck yes
+#GSSAPIKeyExchange no
 
 # Set this to 'yes' to enable PAM authentication, account processing,
 # and session processing. If this is enabled, PAM authentication will
diff --git a/sshd_config.5 b/sshd_config.5
index 70ccea449..f6b41a2f8 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -646,6 +646,11 @@ Specifies whether to automatically destroy the user's credentials cache
 on logout.
 The default is
 .Cm yes .
+.It Cm GSSAPIKeyExchange
+Specifies whether key exchange based on GSSAPI is allowed. GSSAPI key exchange
+doesn't rely on ssh keys to verify host identity.
+The default is
+.Cm no .
 .It Cm GSSAPIStrictAcceptorCheck
 Determines whether to be strict about the identity of the GSSAPI acceptor
 a client authenticates against.
@@ -660,6 +665,31 @@ machine's default store.
 This facility is provided to assist with operation on multi homed machines.
 The default is
 .Cm yes .
+.It Cm GSSAPIStoreCredentialsOnRekey
+Controls whether the user's GSSAPI credentials should be updated following a
+successful connection rekeying. This option can be used to accepted renewed
+or updated credentials from a compatible client. The default is
+.Dq no .
+.Pp
+For this to work
+.Cm GSSAPIKeyExchange
+needs to be enabled in the server and also used by the client.
+.It Cm GSSAPIKexAlgorithms
+The list of key exchange algorithms that are accepted by GSSAPI
+key exchange. Possible values are
+.Bd -literal -offset 3n
+gss-gex-sha1-,
+gss-group1-sha1-,
+gss-group14-sha1-,
+gss-group14-sha256-,
+gss-group16-sha512-,
+gss-nistp256-sha256-,
+gss-curve25519-sha256-
+.Ed
+.Pp
+The default is
+.Dq gss-gex-sha1-,gss-group14-sha1- .
+This option only applies to protocol version 2 connections using GSSAPI.
 .It Cm HostbasedAcceptedKeyTypes
 Specifies the key types that will be accepted for hostbased authentication
 as a list of comma-separated patterns.
diff --git a/sshkey.c b/sshkey.c
index 57995ee68..fd5b77246 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -154,6 +154,7 @@ static const struct keytype keytypes[] = {
 	    KEY_ECDSA_SK_CERT, NID_X9_62_prime256v1, 1, 0 },
 # endif /* OPENSSL_HAS_ECC */
 #endif /* WITH_OPENSSL */
+	{ "null", "null", NULL, KEY_NULL, 0, 0, 0 },
 	{ NULL, NULL, NULL, -1, -1, 0, 0 }
 };
 
@@ -255,7 +256,7 @@ sshkey_alg_list(int certs_only, int plain_only, int include_sigonly, char sep)
 	const struct keytype *kt;
 
 	for (kt = keytypes; kt->type != -1; kt++) {
-		if (kt->name == NULL)
+		if (kt->name == NULL || kt->type == KEY_NULL)
 			continue;
 		if (!include_sigonly && kt->sigonly)
 			continue;
diff --git a/sshkey.h b/sshkey.h
index 71a3fddcb..37a43a67a 100644
--- a/sshkey.h
+++ b/sshkey.h
@@ -69,6 +69,7 @@ enum sshkey_types {
 	KEY_ECDSA_SK_CERT,
 	KEY_ED25519_SK,
 	KEY_ED25519_SK_CERT,
+	KEY_NULL,
 	KEY_UNSPEC
 };
 
-- 
cgit v1.2.3


From 3309e464e5ae6c940ddd584eed4d2d403f4c168c Mon Sep 17 00:00:00 2001
From: Colin Watson <cjwatson@debian.org>
Date: Sun, 9 Feb 2014 16:09:58 +0000
Subject: Allow harmless group-writability

Allow secure files (~/.ssh/config, ~/.ssh/authorized_keys, etc.) to be
group-writable, provided that the group in question contains only the file's
owner.  Rejected upstream for IMO incorrect reasons (e.g. a misunderstanding
about the contents of gr->gr_mem).  Given that per-user groups and umask 002
are the default setup in Debian (for good reasons - this makes operating in
setgid directories with other groups much easier), we need to permit this by
default.

Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1060
Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314347
Last-Update: 2019-10-09

Patch-Name: user-group-modes.patch
---
 auth-rhosts.c |  6 ++----
 auth.c        |  3 +--
 misc.c        | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 misc.h        |  2 ++
 readconf.c    |  3 +--
 ssh.1         |  2 ++
 ssh_config.5  |  2 ++
 7 files changed, 63 insertions(+), 13 deletions(-)

(limited to 'auth.c')

diff --git a/auth-rhosts.c b/auth-rhosts.c
index 7a10210b6..587f53721 100644
--- a/auth-rhosts.c
+++ b/auth-rhosts.c
@@ -260,8 +260,7 @@ auth_rhosts2(struct passwd *pw, const char *client_user, const char *hostname,
 		return 0;
 	}
 	if (options.strict_modes &&
-	    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-	    (st.st_mode & 022) != 0)) {
+	    !secure_permissions(&st, pw->pw_uid)) {
 		logit("Rhosts authentication refused for %.100s: "
 		    "bad ownership or modes for home directory.", pw->pw_name);
 		auth_debug_add("Rhosts authentication refused for %.100s: "
@@ -287,8 +286,7 @@ auth_rhosts2(struct passwd *pw, const char *client_user, const char *hostname,
 		 * allowing access to their account by anyone.
 		 */
 		if (options.strict_modes &&
-		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-		    (st.st_mode & 022) != 0)) {
+		    !secure_permissions(&st, pw->pw_uid)) {
 			logit("Rhosts authentication refused for %.100s: bad modes for %.200s",
 			    pw->pw_name, buf);
 			auth_debug_add("Bad file modes for %.200s", buf);
diff --git a/auth.c b/auth.c
index 687c57b42..aed3c13ac 100644
--- a/auth.c
+++ b/auth.c
@@ -474,8 +474,7 @@ check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
 		user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
 		if (options.strict_modes &&
 		    (stat(user_hostfile, &st) == 0) &&
-		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-		    (st.st_mode & 022) != 0)) {
+		    !secure_permissions(&st, pw->pw_uid)) {
 			logit("Authentication refused for %.100s: "
 			    "bad owner or modes for %.200s",
 			    pw->pw_name, user_hostfile);
diff --git a/misc.c b/misc.c
index 3a31d5c18..073d3be19 100644
--- a/misc.c
+++ b/misc.c
@@ -61,8 +61,9 @@
 #include <netdb.h>
 #ifdef HAVE_PATHS_H
 # include <paths.h>
-#include <pwd.h>
 #endif
+#include <pwd.h>
+#include <grp.h>
 #ifdef SSH_TUN_OPENBSD
 #include <net/if.h>
 #endif
@@ -1124,6 +1125,55 @@ percent_expand(const char *string, ...)
 #undef EXPAND_MAX_KEYS
 }
 
+int
+secure_permissions(struct stat *st, uid_t uid)
+{
+	if (!platform_sys_dir_uid(st->st_uid) && st->st_uid != uid)
+		return 0;
+	if ((st->st_mode & 002) != 0)
+		return 0;
+	if ((st->st_mode & 020) != 0) {
+		/* If the file is group-writable, the group in question must
+		 * have exactly one member, namely the file's owner.
+		 * (Zero-member groups are typically used by setgid
+		 * binaries, and are unlikely to be suitable.)
+		 */
+		struct passwd *pw;
+		struct group *gr;
+		int members = 0;
+
+		gr = getgrgid(st->st_gid);
+		if (!gr)
+			return 0;
+
+		/* Check primary group memberships. */
+		while ((pw = getpwent()) != NULL) {
+			if (pw->pw_gid == gr->gr_gid) {
+				++members;
+				if (pw->pw_uid != uid)
+					return 0;
+			}
+		}
+		endpwent();
+
+		pw = getpwuid(st->st_uid);
+		if (!pw)
+			return 0;
+
+		/* Check supplementary group memberships. */
+		if (gr->gr_mem[0]) {
+			++members;
+			if (strcmp(pw->pw_name, gr->gr_mem[0]) ||
+			    gr->gr_mem[1])
+				return 0;
+		}
+
+		if (!members)
+			return 0;
+	}
+	return 1;
+}
+
 int
 tun_open(int tun, int mode, char **ifname)
 {
@@ -1909,8 +1959,7 @@ safe_path(const char *name, struct stat *stp, const char *pw_dir,
 		snprintf(err, errlen, "%s is not a regular file", buf);
 		return -1;
 	}
-	if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
-	    (stp->st_mode & 022) != 0) {
+	if (!secure_permissions(stp, uid)) {
 		snprintf(err, errlen, "bad ownership or modes for file %s",
 		    buf);
 		return -1;
@@ -1925,8 +1974,7 @@ safe_path(const char *name, struct stat *stp, const char *pw_dir,
 		strlcpy(buf, cp, sizeof(buf));
 
 		if (stat(buf, &st) == -1 ||
-		    (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
-		    (st.st_mode & 022) != 0) {
+		    !secure_permissions(&st, uid)) {
 			snprintf(err, errlen,
 			    "bad ownership or modes for directory %s", buf);
 			return -1;
diff --git a/misc.h b/misc.h
index 4a05db2da..5db594b91 100644
--- a/misc.h
+++ b/misc.h
@@ -188,6 +188,8 @@ struct notifier_ctx *notify_start(int, const char *, ...)
 	__attribute__((format(printf, 2, 3)));
 void	notify_complete(struct notifier_ctx *);
 
+int	 secure_permissions(struct stat *st, uid_t uid);
+
 #define MINIMUM(a, b)	(((a) < (b)) ? (a) : (b))
 #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
 #define ROUNDUP(x, y)   ((((x)+((y)-1))/(y))*(y))
diff --git a/readconf.c b/readconf.c
index 2399208f8..7f251dd4a 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1902,8 +1902,7 @@ read_config_file_depth(const char *filename, struct passwd *pw,
 
 		if (fstat(fileno(f), &sb) == -1)
 			fatal("fstat %s: %s", filename, strerror(errno));
-		if (((sb.st_uid != 0 && sb.st_uid != getuid()) ||
-		    (sb.st_mode & 022) != 0))
+		if (!secure_permissions(&sb, getuid()))
 			fatal("Bad owner or permissions on %s", filename);
 	}
 
diff --git a/ssh.1 b/ssh.1
index db5c65bc7..cf991e4ee 100644
--- a/ssh.1
+++ b/ssh.1
@@ -1506,6 +1506,8 @@ The file format and configuration options are described in
 .Xr ssh_config 5 .
 Because of the potential for abuse, this file must have strict permissions:
 read/write for the user, and not writable by others.
+It may be group-writable provided that the group in question contains only
+the user.
 .Pp
 .It Pa ~/.ssh/environment
 Contains additional definitions for environment variables; see
diff --git a/ssh_config.5 b/ssh_config.5
index 3079db19b..e61a0fd43 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -1952,6 +1952,8 @@ The format of this file is described above.
 This file is used by the SSH client.
 Because of the potential for abuse, this file must have strict permissions:
 read/write for the user, and not writable by others.
+It may be group-writable provided that the group in question contains only
+the user.
 .It Pa /etc/ssh/ssh_config
 Systemwide configuration file.
 This file provides defaults for those
-- 
cgit v1.2.3