1 files changed, 162 insertions, 0 deletions

diff --git a/debian/patches/debian-banner.patch b/debian/patches/debian-banner.patch
new file mode 100644
index 000000000..82cc37c1b
--- /dev/null
+++ b/debian/patches/debian-banner.patch
@@ -0,0 +1,162 @@
+From 6353ee79cc71ef33a0a34d2d769a5fe327f6260d Mon Sep 17 00:00:00 2001
+From: Kees Cook <kees@debian.org>
+Date: Sun, 9 Feb 2014 16:10:06 +0000
+Subject: Add DebianBanner server configuration option
+
+Setting this to "no" causes sshd to omit the Debian revision from its
+initial protocol handshake, for those scared by package-versioning.patch.
+
+Bug-Debian: http://bugs.debian.org/562048
+Forwarded: not-needed
+Last-Update: 2020-06-07
+
+Patch-Name: debian-banner.patch
+---
+ kex.c         | 5 +++--
+ kex.h         | 2 +-
+ servconf.c    | 9 +++++++++
+ servconf.h    | 2 ++
+ sshconnect.c  | 2 +-
+ sshd.c        | 2 +-
+ sshd_config.5 | 5 +++++
+ 7 files changed, 22 insertions(+), 5 deletions(-)
+
+diff --git a/kex.c b/kex.c
+index ce7bb5b3b..763c45536 100644
+--- a/kex.c
++++ b/kex.c
+@@ -1225,7 +1225,7 @@ send_error(struct ssh *ssh, char *msg)
+  */
+ int
+ kex_exchange_identification(struct ssh *ssh, int timeout_ms,
+-    const char *version_addendum)
++    int debian_banner, const char *version_addendum)
+ {
+        int remote_major, remote_minor, mismatch, oerrno = 0;
+        size_t len, i, n;
+@@ -1243,7 +1243,8 @@ kex_exchange_identification(struct ssh *ssh, int timeout_ms,
+        if (version_addendum != NULL && *version_addendum == '\0')
+                version_addendum = NULL;
+        if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%.100s%s%s\r\n",
+-          PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_RELEASE,
++          PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
++           debian_banner ? SSH_RELEASE : SSH_RELEASE_MINIMUM,
+            version_addendum == NULL ? "" : " ",
+            version_addendum == NULL ? "" : version_addendum)) != 0) {
+                oerrno = errno;
+diff --git a/kex.h b/kex.h
+index fe7141414..938dca03b 100644
+--- a/kex.h
++++ b/kex.h
+@@ -194,7 +194,7 @@ 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 *);
++int     kex_exchange_identification(struct ssh *, int, int, const char *);
+ 
+ struct kex *kex_new(void);
+ int     kex_ready(struct ssh *, char *[PROPOSAL_MAX]);
+diff --git a/servconf.c b/servconf.c
+index 21abe41ac..f9eb778d6 100644
+--- a/servconf.c
++++ b/servconf.c
+@@ -195,6 +195,7 @@ initialize_server_options(ServerOptions *options)
+        options->fingerprint_hash = -1;
+        options->disable_forwarding = -1;
+        options->expose_userauth_info = -1;
++       options->debian_banner = -1;
+ }
+ 
+ /* Returns 1 if a string option is unset or set to "none" or 0 otherwise. */
+@@ -469,6 +470,8 @@ fill_default_server_options(ServerOptions *options)
+                options->expose_userauth_info = 0;
+        if (options->sk_provider == NULL)
+                options->sk_provider = xstrdup("internal");
++       if (options->debian_banner == -1)
++               options->debian_banner = 1;
+ 
+        assemble_algorithms(options);
+ 
+@@ -548,6 +551,7 @@ typedef enum {
+        sStreamLocalBindMask, sStreamLocalBindUnlink,
+        sAllowStreamLocalForwarding, sFingerprintHash, sDisableForwarding,
+        sExposeAuthInfo, sRDomain, sPubkeyAuthOptions, sSecurityKeyProvider,
++       sDebianBanner,
+        sDeprecated, sIgnore, sUnsupported
+ } ServerOpCodes;
+ 
+@@ -712,6 +716,7 @@ static struct {
+        { "rdomain", sRDomain, SSHCFG_ALL },
+        { "casignaturealgorithms", sCASignatureAlgorithms, SSHCFG_ALL },
+        { "securitykeyprovider", sSecurityKeyProvider, SSHCFG_GLOBAL },
++       { "debianbanner", sDebianBanner, SSHCFG_GLOBAL },
+        { NULL, sBadOption, 0 }
+ };
+ 
+@@ -2402,6 +2407,10 @@ process_server_config_line_depth(ServerOptions *options, char *line,
+                        *charptr = xstrdup(arg);
+                break;
+ 
++       case sDebianBanner:
++               intptr = &options->debian_banner;
++               goto parse_flag;
++
+        case sDeprecated:
+        case sIgnore:
+        case sUnsupported:
+diff --git a/servconf.h b/servconf.h
+index f10908e5b..4afdf24d0 100644
+--- a/servconf.h
++++ b/servconf.h
+@@ -227,6 +227,8 @@ typedef struct {
+        int     expose_userauth_info;
+        u_int64_t timing_secret;
+        char   *sk_provider;
++
++       int     debian_banner;
+ }       ServerOptions;
+ 
+ /* Information about the incoming connection as used by Match */
+diff --git a/sshconnect.c b/sshconnect.c
+index 3ae20b74e..bab3916d8 100644
+--- a/sshconnect.c
++++ b/sshconnect.c
+@@ -1296,7 +1296,7 @@ ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
+        lowercase(host);
+ 
+        /* Exchange protocol version identification strings with the server. */
+-       if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
++       if ((r = kex_exchange_identification(ssh, timeout_ms, 1, NULL)) != 0)
+                sshpkt_fatal(ssh, r, "banner exchange");
+ 
+        /* Put the connection into non-blocking mode. */
+diff --git a/sshd.c b/sshd.c
+index 38d281ab4..50f2726bf 100644
+--- a/sshd.c
++++ b/sshd.c
+@@ -2232,7 +2232,7 @@ main(int ac, char **av)
+        if (!debug_flag)
+                alarm(options.login_grace_time);
+ 
+-       if ((r = kex_exchange_identification(ssh, -1,
++       if ((r = kex_exchange_identification(ssh, -1, options.debian_banner,
+            options.version_addendum)) != 0)
+                sshpkt_fatal(ssh, r, "banner exchange");
+ 
+diff --git a/sshd_config.5 b/sshd_config.5
+index 6457620bb..33dc0c675 100644
+--- a/sshd_config.5
++++ b/sshd_config.5
+@@ -540,6 +540,11 @@ or
+ .Cm no .
+ The default is
+ .Cm yes .
++.It Cm DebianBanner
++Specifies whether the distribution-specified extra version suffix is
++included during initial protocol handshake.
++The default is
++.Cm yes .
+ .It Cm DenyGroups
+ This keyword can be followed by a list of group name patterns, separated
+ by spaces.