6 files changed, 45 insertions, 11 deletions

diff --git a/ChangeLog b/ChangeLog
index 9c9b3fd0c..a8312a5ef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -33,6 +33,10 @@
      [ssh-keyscan.1 ssh-keyscan.c]
      now that sshd defaults to offering ECDSA keys, ssh-keyscan should also
      look for them by default; bz#1971
+   - djm@cvs.openbsd.org 2012/04/12 02:42:32
+     [servconf.c servconf.h sshd.c sshd_config sshd_config.5]
+     VersionAddendum option to allow server operators to append some arbitrary
+     text to the SSH-... banner; ok deraadt@ "don't care" markus@
 
 20120420
  - (djm) [contrib/caldera/openssh.spec contrib/redhat/openssh.spec]
diff --git a/servconf.c b/servconf.c
index 6de77164e..a8a40f97e 100644
--- a/servconf.c
+++ b/servconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.c,v 1.224 2012/03/29 23:54:36 dtucker Exp $ */
+/* $OpenBSD: servconf.c,v 1.225 2012/04/12 02:42:32 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -138,6 +138,7 @@ initialize_server_options(ServerOptions *options)
         options->authorized_principals_file = NULL;
         options->ip_qos_interactive = -1;
         options->ip_qos_bulk = -1;
+        options->version_addendum = NULL;
 }
 
 void
@@ -277,7 +278,8 @@ fill_default_server_options(ServerOptions *options)
                 options->ip_qos_interactive = IPTOS_LOWDELAY;
         if (options->ip_qos_bulk == -1)
                 options->ip_qos_bulk = IPTOS_THROUGHPUT;
-
+        if (options->version_addendum == NULL)
+                options->version_addendum = xstrdup("");
         /* Turn privilege separation on by default */
         if (use_privsep == -1)
                 use_privsep = PRIVSEP_ON;
@@ -323,7 +325,7 @@ typedef enum {
         sUsePrivilegeSeparation, sAllowAgentForwarding,
         sZeroKnowledgePasswordAuthentication, sHostCertificate,
         sRevokedKeys, sTrustedUserCAKeys, sAuthorizedPrincipalsFile,
-        sKexAlgorithms, sIPQoS,
+        sKexAlgorithms, sIPQoS, sVersionAddendum,
         sDeprecated, sUnsupported
 } ServerOpCodes;
 
@@ -448,6 +450,7 @@ static struct {
         { "authorizedprincipalsfile", sAuthorizedPrincipalsFile, SSHCFG_ALL },
         { "kexalgorithms", sKexAlgorithms, SSHCFG_GLOBAL },
         { "ipqos", sIPQoS, SSHCFG_ALL },
+        { "versionaddendum", sVersionAddendum, SSHCFG_GLOBAL },
         { NULL, sBadOption, 0 }
 };
 
@@ -1403,6 +1406,22 @@ process_server_config_line(ServerOptions *options, char *line,
                 }
                 break;
 
+        case sVersionAddendum:
+                if (cp == NULL)
+                        fatal("%.200s line %d: Missing argument.", filename,
+                            linenum);
+                len = strspn(cp, WHITESPACE);
+                if (*activep && options->version_addendum == NULL) {
+                        if (strcasecmp(cp + len, "none") == 0)
+                                options->version_addendum = xstrdup("");
+                        else if (strchr(cp + len, '\r') != NULL)
+                                fatal("%.200s line %d: Invalid argument",
+                                    filename, linenum);
+                        else
+                                options->version_addendum = xstrdup(cp + len);
+                }
+                return 0;
+
         case sDeprecated:
                 logit("%s line %d: Deprecated option %s",
                     filename, linenum, arg);
@@ -1766,6 +1785,7 @@ dump_config(ServerOptions *o)
         dump_cfg_string(sRevokedKeys, o->revoked_keys_file);
         dump_cfg_string(sAuthorizedPrincipalsFile,
             o->authorized_principals_file);
+        dump_cfg_string(sVersionAddendum, o->version_addendum);
 
         /* string arguments requiring a lookup */
         dump_cfg_string(sLogLevel, log_level_name(o->log_level));
diff --git a/servconf.h b/servconf.h
index 89f38e20f..66ba387dd 100644
--- a/servconf.h
+++ b/servconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.h,v 1.99 2011/06/22 21:57:01 djm Exp $ */
+/* $OpenBSD: servconf.h,v 1.100 2012/04/12 02:42:32 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -166,6 +166,8 @@ typedef struct {
         char   *revoked_keys_file;
         char   *trusted_user_ca_keys;
         char   *authorized_principals_file;
+
+        char   *version_addendum;       /* Appended to SSH banner */
 }       ServerOptions;
 
 /*
diff --git a/sshd.c b/sshd.c
index fddbc9d37..b7066df5c 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.389 2012/04/11 13:26:40 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.390 2012/04/12 02:42:32 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -419,9 +419,11 @@ sshd_exchange_identification(int sock_in, int sock_out)
                 major = PROTOCOL_MAJOR_1;
                 minor = PROTOCOL_MINOR_1;
         }
-        snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
-            SSH_VERSION, newline);
-        server_version_string = xstrdup(buf);
+
+        xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s",
+            major, minor, SSH_VERSION,
+            *options.version_addendum == '\0' ? "" : " ",
+            options.version_addendum, newline);
 
         /* Send our protocol version identification. */
         if (roaming_atomicio(vwrite, sock_out, server_version_string,
diff --git a/sshd_config b/sshd_config
index 473e86654..99dbd8580 100644
--- a/sshd_config
+++ b/sshd_config
@@ -1,4 +1,4 @@
-#       $OpenBSD: sshd_config,v 1.84 2011/05/23 03:30:07 djm Exp $
+#       $OpenBSD: sshd_config,v 1.85 2012/04/12 02:42:32 djm Exp $
 
 # This is the sshd server system-wide configuration file.  See
 # sshd_config(5) for more information.
@@ -107,6 +107,7 @@ AuthorizedKeysFile	.ssh/authorized_keys
 #MaxStartups 10
 #PermitTunnel no
 #ChrootDirectory none
+#VersionAddendum none
 
 # no default banner path
 #Banner none
diff --git a/sshd_config.5 b/sshd_config.5
index 4ef8b9e6d..1522355a8 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 1.136 2011/09/09 00:43:00 djm Exp $
-.Dd $Mdocdate: September 9 2011 $
+.\" $OpenBSD: sshd_config.5,v 1.137 2012/04/12 02:42:32 djm Exp $
+.Dd $Mdocdate: April 12 2012 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -1079,6 +1079,11 @@ is set to
 .Dq sandbox
 then the pre-authentication unprivileged process is subject to additional
 restrictions.
+.It Cm VersionAddendum
+Optionally specifies additional text to append to the SSH protocol banner
+sent by the server upon connection.
+The default is
+.Dq none .
 .It Cm X11DisplayOffset
 Specifies the first display number available for
 .Xr sshd 8 Ns 's