- markus@cvs.openbsd.org 2006/07/11 18:50:48

     [clientloop.c ssh.1 ssh.c channels.c ssh_config.5 readconf.h session.c
     channels.h readconf.c]
     add ExitOnForwardFailure: terminate the connection if ssh(1)
     cannot set up all requested dynamic, local, and remote port
     forwardings. ok djm, dtucker, stevesk, jmc

10 files changed, 79 insertions, 26 deletions

diff --git a/ChangeLog b/ChangeLog
index b5c849806..74bfb0d3b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -23,6 +23,12 @@
      Only copy the part of environment variable that we actually use.  Prevents
      ssh bailing when SendEnv is used and an environment variable with a really
      long value exists.  ok djm@
+   - markus@cvs.openbsd.org 2006/07/11 18:50:48
+     [clientloop.c ssh.1 ssh.c channels.c ssh_config.5 readconf.h session.c
+     channels.h readconf.c]
+     add ExitOnForwardFailure: terminate the connection if ssh(1)
+     cannot set up all requested dynamic, local, and remote port
+     forwardings. ok djm, dtucker, stevesk, jmc
 
 20060711
  - (dtucker) [configure.ac ssh-keygen.c openbsd-compat/bsd-openpty.c
@@ -4872,4 +4878,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.4395 2006/07/12 12:16:23 dtucker Exp $
+$Id: ChangeLog,v 1.4396 2006/07/12 12:17:10 dtucker Exp $
diff --git a/channels.c b/channels.c
index cd68efded..51718578b 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.252 2006/07/10 12:08:08 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.253 2006/07/11 18:50:47 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2481,7 +2481,7 @@ channel_setup_remote_fwd_listener(const char *listen_address,
  * the secure channel to host:port from local side.
  */
 
-void
+int
 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
     const char *host_to_connect, u_short port_to_connect)
 {
@@ -2525,7 +2525,6 @@ channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
                         success = 1;
                         break;
                 case SSH_SMSG_FAILURE:
-                        logit("Warning: Server denied remote port forwarding.");
                         break;
                 default:
                         /* Unknown packet */
@@ -2539,6 +2538,7 @@ channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
                 permitted_opens[num_permitted_opens].listen_port = listen_port;
                 num_permitted_opens++;
         }
+        return (success ? 0 : -1);
 }
 
 /*
@@ -2578,12 +2578,13 @@ channel_request_rforward_cancel(const char *host, u_short port)
 /*
  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
  * listening for the port, and sends back a success reply (or disconnect
- * message if there was an error).  This never returns if there was an error.
+ * message if there was an error).
  */
-void
+int
 channel_input_port_forward_request(int is_root, int gateway_ports)
 {
         u_short port, host_port;
+        int success = 0;
         char *hostname;
 
         /* Get arguments from the packet. */
@@ -2605,11 +2606,13 @@ channel_input_port_forward_request(int is_root, int gateway_ports)
 #endif
 
         /* Initiate forwarding */
-        channel_setup_local_fwd_listener(NULL, port, hostname,
+        success = channel_setup_local_fwd_listener(NULL, port, hostname,
             host_port, gateway_ports);
 
         /* Free the argument string. */
         xfree(hostname);
+
+        return (success ? 0 : -1);
 }
 
 /*
@@ -2628,7 +2631,7 @@ void
 channel_add_permitted_opens(char *host, int port)
 {
         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
-                fatal("channel_request_remote_forwarding: too many forwards");
+                fatal("channel_add_permitted_opens: too many forwards");
         debug("allow port forwarding to host %s port %d", host, port);
 
         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
diff --git a/channels.h b/channels.h
index ee1d260fd..d21319a2b 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.h,v 1.84 2006/03/25 22:22:42 djm Exp $ */
+/* $OpenBSD: channels.h,v 1.85 2006/07/11 18:50:47 markus Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -208,10 +208,10 @@ void	 channel_set_af(int af);
 void     channel_permit_all_opens(void);
 void     channel_add_permitted_opens(char *, int);
 void     channel_clear_permitted_opens(void);
-void     channel_input_port_forward_request(int, int);
+int      channel_input_port_forward_request(int, int);
 int      channel_connect_to(const char *, u_short);
 int      channel_connect_by_listen_address(u_short);
-void     channel_request_remote_forwarding(const char *, u_short,
+int      channel_request_remote_forwarding(const char *, u_short,
              const char *, u_short);
 int      channel_setup_local_fwd_listener(const char *, u_short,
              const char *, u_short, int);
diff --git a/clientloop.c b/clientloop.c
index c59d573c5..6cb2a7ac7 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.166 2006/07/08 21:47:12 stevesk Exp $ */
+/* $OpenBSD: clientloop.c,v 1.167 2006/07/11 18:50:47 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -996,9 +996,12 @@ process_cmdline(void)
                                 goto out;
                         }
                 } else {
-                        channel_request_remote_forwarding(fwd.listen_host,
+                        if (channel_request_remote_forwarding(fwd.listen_host,
                             fwd.listen_port, fwd.connect_host,
-                            fwd.connect_port);
+                            fwd.connect_port) < 0) {
+                                logit("Port forwarding failed.");
+                                goto out;
+                        }
                 }
 
                 logit("Forwarding port.");
diff --git a/readconf.c b/readconf.c
index df5e566a5..d25f93012 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.152 2006/07/05 02:42:09 stevesk Exp $ */
+/* $OpenBSD: readconf.c,v 1.153 2006/07/11 18:50:48 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -102,6 +102,7 @@
 typedef enum {
         oBadOption,
         oForwardAgent, oForwardX11, oForwardX11Trusted, oGatewayPorts,
+        oExitOnForwardFailure,
         oPasswordAuthentication, oRSAAuthentication,
         oChallengeResponseAuthentication, oXAuthLocation,
         oIdentityFile, oHostName, oPort, oCipher, oRemoteForward, oLocalForward,
@@ -132,6 +133,7 @@ static struct {
         { "forwardagent", oForwardAgent },
         { "forwardx11", oForwardX11 },
         { "forwardx11trusted", oForwardX11Trusted },
+        { "exitonforwardfailure", oExitOnForwardFailure },
         { "xauthlocation", oXAuthLocation },
         { "gatewayports", oGatewayPorts },
         { "useprivilegedport", oUsePrivilegedPort },
@@ -386,6 +388,10 @@ parse_flag:
                 intptr = &options->gateway_ports;
                 goto parse_flag;
 
+        case oExitOnForwardFailure:
+                intptr = &options->exit_on_forward_failure;
+                goto parse_flag;
+
         case oUsePrivilegedPort:
                 intptr = &options->use_privileged_port;
                 goto parse_flag;
@@ -987,6 +993,7 @@ initialize_options(Options * options)
         options->forward_agent = -1;
         options->forward_x11 = -1;
         options->forward_x11_trusted = -1;
+        options->exit_on_forward_failure = -1;
         options->xauth_location = NULL;
         options->gateway_ports = -1;
         options->use_privileged_port = -1;
@@ -1067,6 +1074,8 @@ fill_default_options(Options * options)
                 options->forward_x11 = 0;
         if (options->forward_x11_trusted == -1)
                 options->forward_x11_trusted = 0;
+        if (options->exit_on_forward_failure == -1)
+                options->exit_on_forward_failure = 0;
         if (options->xauth_location == NULL)
                 options->xauth_location = _PATH_XAUTH;
         if (options->gateway_ports == -1)
diff --git a/readconf.h b/readconf.h
index 7fc2ea47c..e99b1ff25 100644
--- a/readconf.h
+++ b/readconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.h,v 1.69 2006/03/25 22:22:43 djm Exp $ */
+/* $OpenBSD: readconf.h,v 1.70 2006/07/11 18:50:48 markus Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -34,6 +34,7 @@ typedef struct {
         int     forward_agent;  /* Forward authentication agent. */
         int     forward_x11;    /* Forward X11 display. */
         int     forward_x11_trusted;    /* Trust Forward X11 display. */
+        int     exit_on_forward_failure;        /* Exit if bind(2) fails for -L/-R */
         char   *xauth_location; /* Location for xauth program */
         int     gateway_ports;  /* Allow remote connects to forwarded ports. */
         int     use_privileged_port;    /* Don't use privileged port if false. */
diff --git a/session.c b/session.c
index 0a321be30..33be91545 100644
--- a/session.c
+++ b/session.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.207 2006/07/08 21:48:53 stevesk Exp $ */
+/* $OpenBSD: session.c,v 1.208 2006/07/11 18:50:48 markus Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -338,7 +338,11 @@ do_authenticated1(Authctxt *authctxt)
                                 break;
                         }
                         debug("Received TCP/IP port forwarding request.");
-                        channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports);
+                        if (channel_input_port_forward_request(s->pw->pw_uid == 0,
+                            options.gateway_ports) < 0) {
+                                debug("Port forwarding failed.");
+                                break;
+                        }
                         success = 1;
                         break;
 
diff --git a/ssh.1 b/ssh.1
index f44b6f29a..6e41bcd8b 100644
--- a/ssh.1
+++ b/ssh.1
@@ -34,7 +34,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh.1,v 1.262 2006/07/02 23:01:55 stevesk Exp $
+.\" $OpenBSD: ssh.1,v 1.263 2006/07/11 18:50:48 markus Exp $
 .Dd September 25, 1999
 .Dt SSH 1
 .Os
@@ -449,6 +449,7 @@ For full details of the options listed below, and their possible values, see
 .It ControlPath
 .It DynamicForward
 .It EscapeChar
+.It ExitOnForwardFailure
 .It ForwardAgent
 .It ForwardX11
 .It ForwardX11Trusted
diff --git a/ssh.c b/ssh.c
index bd92206d4..2e0ef2f9f 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.282 2006/07/11 10:12:07 dtucker Exp $ */
+/* $OpenBSD: ssh.c,v 1.283 2006/07/11 18:50:48 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -817,6 +817,8 @@ ssh_init_forwarding(void)
                     options.local_forwards[i].connect_port,
                     options.gateway_ports);
         }
+        if (i > 0 && success != i && options.exit_on_forward_failure)
+                fatal("Could not request local forwarding.");
         if (i > 0 && success == 0)
                 error("Could not request local forwarding.");
 
@@ -829,11 +831,17 @@ ssh_init_forwarding(void)
                     options.remote_forwards[i].listen_port,
                     options.remote_forwards[i].connect_host,
                     options.remote_forwards[i].connect_port);
-                channel_request_remote_forwarding(
+                if (channel_request_remote_forwarding(
                     options.remote_forwards[i].listen_host,
                     options.remote_forwards[i].listen_port,
                     options.remote_forwards[i].connect_host,
-                    options.remote_forwards[i].connect_port);
+                    options.remote_forwards[i].connect_port) < 0) {
+                        if (options.exit_on_forward_failure)
+                                fatal("Could not request remote forwarding.");
+                        else
+                                logit("Warning: Could not request remote "
+                                    "forwarding.");
+                }
         }
 }
 
@@ -1015,9 +1023,16 @@ client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
             options.remote_forwards[i].listen_port,
             options.remote_forwards[i].connect_host,
             options.remote_forwards[i].connect_port);
-        if (type == SSH2_MSG_REQUEST_FAILURE)
-                logit("Warning: remote port forwarding failed for listen "
-                    "port %d", options.remote_forwards[i].listen_port);
+        if (type == SSH2_MSG_REQUEST_FAILURE) {
+                if (options.exit_on_forward_failure)
+                        fatal("Error: remote port forwarding failed for "
+                            "listen port %d",
+                            options.remote_forwards[i].listen_port);
+                else
+                        logit("Warning: remote port forwarding failed for "
+                            "listen port %d",
+                            options.remote_forwards[i].listen_port);
+        }
 }
 
 static void
diff --git a/ssh_config.5 b/ssh_config.5
index 68ec311b2..55ca55303 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -34,7 +34,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh_config.5,v 1.95 2006/07/02 17:12:58 stevesk Exp $
+.\" $OpenBSD: ssh_config.5,v 1.96 2006/07/11 18:50:48 markus Exp $
 .Dd September 25, 1999
 .Dt SSH_CONFIG 5
 .Os
@@ -385,6 +385,17 @@ followed by a letter, or
 to disable the escape
 character entirely (making the connection transparent for binary
 data).
+.It Cm ExitOnForwardFailure
+Specifies whether
+.Xr ssh 1
+should terminate the connection if it cannot set up all requested
+dynamic, local, and remote port forwardings.
+The argument must be
+.Dq yes
+or
+.Dq no .
+The default is
+.Dq no .
 .It Cm ForwardAgent
 Specifies whether the connection to the authentication agent (if any)
 will be forwarded to the remote machine.