upstream commit

pass negotiated signing algorithm though to
sshkey_verify() and check that the negotiated algorithm matches the type in
the signature (only matters for RSA SHA1/SHA2 sigs). ok markus@

OpenBSD-Commit-ID: 735fb15bf4adc060d3bee9d047a4bcaaa81b1af9

19 files changed, 58 insertions, 58 deletions

diff --git a/auth2-hostbased.c b/auth2-hostbased.c
index 92758b38c..8112cfaa3 100644
--- a/auth2-hostbased.c
+++ b/auth2-hostbased.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-hostbased.c,v 1.31 2017/06/24 06:34:38 djm Exp $ */
+/* $OpenBSD: auth2-hostbased.c,v 1.32 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -144,7 +144,7 @@ userauth_hostbased(struct ssh *ssh)
         authenticated = 0;
         if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
             PRIVSEP(sshkey_verify(key, sig, slen,
-            sshbuf_ptr(b), sshbuf_len(b), ssh->compat)) == 0)
+            sshbuf_ptr(b), sshbuf_len(b), pkalg, ssh->compat)) == 0)
                 authenticated = 1;
 
         auth2_record_key(authctxt, authenticated, key);
diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index 169839b01..0707b8ab3 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.71 2017/09/07 23:48:09 djm Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.72 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -198,7 +198,7 @@ userauth_pubkey(struct ssh *ssh)
                 authenticated = 0;
                 if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
                     PRIVSEP(sshkey_verify(key, sig, slen, sshbuf_ptr(b),
-                    sshbuf_len(b), ssh->compat)) == 0) {
+                    sshbuf_len(b), pkalg, ssh->compat)) == 0) {
                         authenticated = 1;
                 }
                 sshbuf_free(b);
diff --git a/clientloop.c b/clientloop.c
index e3824ccd9..3ce5d930e 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.307 2017/11/25 05:58:47 dtucker Exp $ */
+/* $OpenBSD: clientloop.c,v 1.308 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1934,7 +1934,8 @@ client_global_hostkeys_private_confirm(struct ssh *ssh, int type,
                         goto out;
                 }
                 if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
-                    sshbuf_ptr(signdata), sshbuf_len(signdata), 0)) != 0) {
+                    sshbuf_ptr(signdata), sshbuf_len(signdata),
+                    ssh->kex->hostkey_alg, 0)) != 0) {
                         error("%s: server gave bad signature for %s key %zu",
                             __func__, sshkey_type(ctx->keys[i]), i);
                         goto out;
diff --git a/hash.c b/hash.c
index bc87808a3..21f464e67 100644
--- a/hash.c
+++ b/hash.c
@@ -1,5 +1,7 @@
 /* $OpenBSD: hash.c,v 1.4 2017/12/14 21:07:39 naddy Exp $ */
 
+#include "includes.h"
+
 #include "crypto_api.h"
 
 #include <stdarg.h>
diff --git a/kexc25519c.c b/kexc25519c.c
index e488013e9..a8d92149c 100644
--- a/kexc25519c.c
+++ b/kexc25519c.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexc25519c.c,v 1.8 2017/05/31 04:17:12 djm Exp $ */
+/* $OpenBSD: kexc25519c.c,v 1.9 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -141,7 +141,7 @@ input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh)
                 goto out;
 
         if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
-            ssh->compat)) != 0)
+            kex->hostkey_alg, ssh->compat)) != 0)
                 goto out;
 
         /* save session id */
diff --git a/kexdhc.c b/kexdhc.c
index 9864ee2ec..5e1a353a5 100644
--- a/kexdhc.c
+++ b/kexdhc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexdhc.c,v 1.20 2017/05/30 14:23:52 markus Exp $ */
+/* $OpenBSD: kexdhc.c,v 1.21 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  *
@@ -183,7 +183,7 @@ input_kex_dh(int type, u_int32_t seq, struct ssh *ssh)
                 goto out;
 
         if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
-            ssh->compat)) != 0)
+            kex->hostkey_alg, ssh->compat)) != 0)
                 goto out;
 
         /* save session id */
diff --git a/kexecdhc.c b/kexecdhc.c
index d8a8b660f..67669b3bf 100644
--- a/kexecdhc.c
+++ b/kexecdhc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexecdhc.c,v 1.11 2017/05/30 14:23:52 markus Exp $ */
+/* $OpenBSD: kexecdhc.c,v 1.12 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -188,7 +188,7 @@ input_kex_ecdh_reply(int type, u_int32_t seq, struct ssh *ssh)
                 goto out;
 
         if ((r = sshkey_verify(server_host_key, signature, slen, hash,
-            hashlen, ssh->compat)) != 0)
+            hashlen, kex->hostkey_alg, ssh->compat)) != 0)
                 goto out;
 
         /* save session id */
diff --git a/kexgexc.c b/kexgexc.c
index cd1128752..6f8cf48a6 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.25 2017/05/30 14:23:52 markus Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.26 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -230,7 +230,7 @@ input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
                 goto out;
 
         if ((r = sshkey_verify(server_host_key, signature, slen, hash,
-            hashlen, ssh->compat)) != 0)
+            hashlen, kex->hostkey_alg, ssh->compat)) != 0)
                 goto out;
 
         /* save session id */
diff --git a/key.c b/key.c
index 6e338c495..a05fdd3c0 100644
--- a/key.c
+++ b/key.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: key.c,v 1.131 2017/05/30 14:16:41 markus Exp $ */
+/* $OpenBSD: key.c,v 1.132 2017/12/18 02:25:15 djm Exp $ */
 /*
  * placed in the public domain
  */
@@ -95,21 +95,6 @@ key_sign(const Key *key, u_char **sigp, u_int *lenp,
         return 0;
 }
 
-int
-key_verify(const Key *key, const u_char *signature, u_int signaturelen,
-    const u_char *data, u_int datalen)
-{
-        int r;
-
-        if ((r = sshkey_verify(key, signature, signaturelen,
-            data, datalen, datafellows)) != 0) {
-                fatal_on_fatal_errors(r, __func__, 0);
-                error("%s: %s", __func__, ssh_err(r));
-                return r == SSH_ERR_SIGNATURE_INVALID ? 0 : -1;
-        }
-        return 1;
-}
-
 Key *
 key_demote(const Key *k)
 {
diff --git a/key.h b/key.h
index a14f37037..fd59cbf54 100644
--- a/key.h
+++ b/key.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: key.h,v 1.51 2017/05/30 14:16:41 markus Exp $ */
+/* $OpenBSD: key.h,v 1.52 2017/12/18 02:25:15 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -58,7 +58,6 @@ int	 key_to_blob(const Key *, u_char **, u_int *);
 
 int      key_sign(const Key *, u_char **, u_int *, const u_char *, u_int,
     const char *);
-int      key_verify(const Key *, const u_char *, u_int, const u_char *, u_int);
 
 /* authfile.c */
 Key     *key_load_cert(const char *);
diff --git a/krl.c b/krl.c
index 086fc20e5..379153247 100644
--- a/krl.c
+++ b/krl.c
@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $OpenBSD: krl.c,v 1.40 2017/05/31 09:15:42 deraadt Exp $ */
+/* $OpenBSD: krl.c,v 1.41 2017/12/18 02:25:15 djm Exp $ */
 
 #include "includes.h"
 
@@ -1014,7 +1014,7 @@ ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp,
                 }
                 /* Check signature over entire KRL up to this point */
                 if ((r = sshkey_verify(key, blob, blen,
-                    sshbuf_ptr(buf), sig_off, 0)) != 0)
+                    sshbuf_ptr(buf), sig_off, NULL, 0)) != 0)
                         goto out;
                 /* Check if this key has already signed this KRL */
                 for (i = 0; i < nca_used; i++) {
diff --git a/monitor.c b/monitor.c
index a0ad9857d..5b8f0ef65 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.175 2017/10/05 15:52:03 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.176 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -1339,12 +1339,14 @@ mm_answer_keyverify(int sock, struct sshbuf *m)
 {
         struct sshkey *key;
         u_char *signature, *data, *blob;
+        char *sigalg;
         size_t signaturelen, datalen, bloblen;
         int r, ret, valid_data = 0, encoded_ret;
 
         if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 ||
             (r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 ||
-            (r = sshbuf_get_string(m, &data, &datalen)) != 0)
+            (r = sshbuf_get_string(m, &data, &datalen)) != 0 ||
+            (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
         if (hostbased_cuser == NULL || hostbased_chost == NULL ||
@@ -1373,7 +1375,7 @@ mm_answer_keyverify(int sock, struct sshbuf *m)
                 fatal("%s: bad signature data blob", __func__);
 
         ret = sshkey_verify(key, signature, signaturelen, data, datalen,
-            active_state->compat);
+            sigalg, active_state->compat);
         debug3("%s: %s %p signature %s", __func__, auth_method, key,
             (ret == 0) ? "verified" : "unverified");
         auth2_record_key(authctxt, ret == 0, key);
diff --git a/monitor_wrap.c b/monitor_wrap.c
index a46628fb1..502d41687 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.95 2017/10/05 15:52:03 djm Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.96 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -441,7 +441,7 @@ mm_key_allowed(enum mm_keytype type, const char *user, const char *host,
 
 int
 mm_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
-    const u_char *data, size_t datalen, u_int compat)
+    const u_char *data, size_t datalen, const char *sigalg, u_int compat)
 {
         Buffer m;
         u_char *blob;
@@ -458,6 +458,7 @@ mm_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
         buffer_put_string(&m, blob, len);
         buffer_put_string(&m, sig, siglen);
         buffer_put_string(&m, data, datalen);
+        buffer_put_cstring(&m, sigalg);
         free(blob);
 
         mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, &m);
diff --git a/monitor_wrap.h b/monitor_wrap.h
index 9e032d204..f5af1e819 100644
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.h,v 1.35 2017/05/31 08:09:45 markus Exp $ */
+/* $OpenBSD: monitor_wrap.h,v 1.36 2017/12/18 02:25:15 djm Exp $ */
 
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@@ -51,7 +51,7 @@ int mm_user_key_allowed(struct passwd *, struct sshkey *, int);
 int mm_hostbased_key_allowed(struct passwd *, const char *,
     const char *, struct sshkey *);
 int mm_sshkey_verify(const struct sshkey *, const u_char *, size_t,
-    const u_char *, size_t, u_int);
+    const u_char *, size_t, const char *, u_int);
 
 #ifdef GSSAPI
 OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **, gss_OID);
diff --git a/serverloop.c b/serverloop.c
index 464c07d2f..fb2980568 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.200 2017/12/10 05:55:29 dtucker Exp $ */
+/* $OpenBSD: serverloop.c,v 1.201 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -715,7 +715,8 @@ server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
                     ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
                     (r = sshkey_puts(key, sigbuf)) != 0 ||
                     (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
-                    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 ||
+                    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
+                    ssh->kex->hostkey_alg, 0)) != 0 ||
                     (r = sshbuf_put_string(resp, sig, slen)) != 0) {
                         error("%s: couldn't prepare signature: %s",
                             __func__, ssh_err(r));
diff --git a/ssh-keygen.c b/ssh-keygen.c
index 02f9b3fb8..d2736eee2 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.308 2017/11/03 05:14:04 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.309 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -539,7 +539,7 @@ do_convert_private_ssh2_from_blob(u_char *blob, u_int blen)
 
         /* try the key */
         if (sshkey_sign(key, &sig, &slen, data, sizeof(data), NULL, 0) != 0 ||
-            sshkey_verify(key, sig, slen, data, sizeof(data), 0) != 0) {
+            sshkey_verify(key, sig, slen, data, sizeof(data), NULL, 0) != 0) {
                 sshkey_free(key);
                 free(sig);
                 return NULL;
diff --git a/ssh-rsa.c b/ssh-rsa.c
index f570ae6d4..9b4de8e8d 100644
--- a/ssh-rsa.c
+++ b/ssh-rsa.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-rsa.c,v 1.62 2017/07/01 13:50:45 djm Exp $ */
+/* $OpenBSD: ssh-rsa.c,v 1.63 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
  *
@@ -198,9 +198,10 @@ ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
 
 int
 ssh_rsa_verify(const struct sshkey *key,
-    const u_char *sig, size_t siglen, const u_char *data, size_t datalen)
+    const u_char *sig, size_t siglen, const u_char *data, size_t datalen,
+    const char *alg)
 {
-        char *ktype = NULL;
+        char *sigtype = NULL;
         int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
         size_t len, diff, modlen, dlen;
         struct sshbuf *b = NULL;
@@ -215,11 +216,17 @@ ssh_rsa_verify(const struct sshkey *key,
 
         if ((b = sshbuf_from(sig, siglen)) == NULL)
                 return SSH_ERR_ALLOC_FAIL;
-        if (sshbuf_get_cstring(b, &ktype, NULL) != 0) {
+        if (sshbuf_get_cstring(b, &sigtype, NULL) != 0) {
                 ret = SSH_ERR_INVALID_FORMAT;
                 goto out;
         }
-        if ((hash_alg = rsa_hash_alg_from_ident(ktype)) == -1) {
+        /* XXX djm: need cert types that reliably yield SHA-2 signatures */
+        if (alg != NULL && strcmp(alg, sigtype) != 0 &&
+            strcmp(alg, "ssh-rsa-cert-v01@openssh.com") != 0) {
+                ret = SSH_ERR_SIGNATURE_INVALID;
+                goto out;
+        }
+        if ((hash_alg = rsa_hash_alg_from_ident(sigtype)) == -1) {
                 ret = SSH_ERR_KEY_TYPE_MISMATCH;
                 goto out;
         }
@@ -263,7 +270,7 @@ ssh_rsa_verify(const struct sshkey *key,
                 explicit_bzero(sigblob, len);
                 free(sigblob);
         }
-        free(ktype);
+        free(sigtype);
         sshbuf_free(b);
         explicit_bzero(digest, sizeof(digest));
         return ret;
diff --git a/sshkey.c b/sshkey.c
index 19f26a117..91e0073ff 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.58 2017/12/18 02:22:29 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.59 2017/12/18 02:25:15 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -1814,7 +1814,7 @@ cert_parse(struct sshbuf *b, struct sshkey *key, struct sshbuf *certbuf)
                 goto out;
         }
         if ((ret = sshkey_verify(key->cert->signature_key, sig, slen,
-            sshbuf_ptr(key->cert->certblob), signed_len, 0)) != 0)
+            sshbuf_ptr(key->cert->certblob), signed_len, NULL, 0)) != 0)
                 goto out;
 
         /* Success */
@@ -2109,11 +2109,12 @@ sshkey_sign(const struct sshkey *key,
 
 /*
  * ssh_key_verify returns 0 for a correct signature  and < 0 on error.
+ * If "alg" specified, then the signature must use that algorithm.
  */
 int
 sshkey_verify(const struct sshkey *key,
     const u_char *sig, size_t siglen,
-    const u_char *data, size_t dlen, u_int compat)
+    const u_char *data, size_t dlen, const char *alg, u_int compat)
 {
         if (siglen == 0 || dlen > SSH_KEY_MAX_SIGN_DATA_SIZE)
                 return SSH_ERR_INVALID_ARGUMENT;
@@ -2129,7 +2130,7 @@ sshkey_verify(const struct sshkey *key,
 # endif /* OPENSSL_HAS_ECC */
         case KEY_RSA_CERT:
         case KEY_RSA:
-                return ssh_rsa_verify(key, sig, siglen, data, dlen);
+                return ssh_rsa_verify(key, sig, siglen, data, dlen, alg);
 #endif /* WITH_OPENSSL */
         case KEY_ED25519:
         case KEY_ED25519_CERT:
diff --git a/sshkey.h b/sshkey.h
index b5346a92d..7efa16ff9 100644
--- a/sshkey.h
+++ b/sshkey.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.h,v 1.22 2017/12/18 02:22:29 djm Exp $ */
+/* $OpenBSD: sshkey.h,v 1.23 2017/12/18 02:25:15 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -178,7 +178,7 @@ int	 sshkey_sigtype(const u_char *, size_t, char **);
 int      sshkey_sign(const struct sshkey *, u_char **, size_t *,
     const u_char *, size_t, const char *, u_int);
 int      sshkey_verify(const struct sshkey *, const u_char *, size_t,
-    const u_char *, size_t, u_int);
+    const u_char *, size_t, const char *, u_int);
 
 /* for debug */
 void    sshkey_dump_ec_point(const EC_GROUP *, const EC_POINT *);
@@ -205,7 +205,8 @@ int ssh_rsa_sign(const struct sshkey *key,
     u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
     const char *ident);
 int ssh_rsa_verify(const struct sshkey *key,
-    const u_char *sig, size_t siglen, const u_char *data, size_t datalen);
+    const u_char *sig, size_t siglen, const u_char *data, size_t datalen,
+    const char *alg);
 int ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat);
 int ssh_dss_verify(const struct sshkey *key,