- djm@cvs.openbsd.org 2004/05/21 11:33:11

     [channels.c channels.h clientloop.c serverloop.c ssh.1]
     bz #756: add support for the cancel-tcpip-forward request for the server and
     the client (through the ~C commandline). reported by z3p AT twistedmatrix.com;
     ok markus@

diff --git a/ChangeLog b/ChangeLog
index c52c60333393b673fa317282cbb2cac40c841cbd..e5e01cdc60cae0d3e509b78daaaaae53f8d9c3c9 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,11 @@
    - markus@cvs.openbsd.org 2004/05/21 08:43:03
      [kex.h moduli.c tildexpand.c]
      add prototypes for -Wall; ok djm
+   - djm@cvs.openbsd.org 2004/05/21 11:33:11
+     [channels.c channels.h clientloop.c serverloop.c ssh.1]
+     bz #756: add support for the cancel-tcpip-forward request for the server and
+     the client (through the ~C commandline). reported by z3p AT twistedmatrix.com;
+     ok markus@
 
 20040523
  - (djm) [sshd_config] Explain consequences of UsePAM=yes a little better in 

diff --git a/channels.c b/channels.c
index 55dc6734220f30aea495848c40dddc72504fb6c1..2b1ce0e5c361f3c5f613b5aae12159df00579b71 100644 (file)
--- a/channels.c
+++ b/channels.c
@@ -39,7 +39,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: channels.c,v 1.201 2004/05/11 19:01:43 deraadt Exp $");
+RCSID("$OpenBSD: channels.c,v 1.202 2004/05/21 11:33:11 djm Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -2228,6 +2228,26 @@ channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_por
        return success;
 }
 
+int
+channel_cancel_rport_listener(const char *host, u_short port)
+{
+       int i, found = 0;
+
+       for(i = 0; i < channels_alloc; i++) {
+               Channel *c = channels[i];
+
+               if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
+                   strncmp(c->path, host, sizeof(c->path)) == 0 &&
+                   c->listening_port == port) {
+                       debug2("%s: close clannel %d", __func__, i);
+                       channel_free(c);
+                       found = 1;
+               }
+       }
+
+       return (found);
+}
+
 /* protocol local port fwd, used by ssh (and sshd in v1) */
 int
 channel_setup_local_fwd_listener(u_short listen_port,
@@ -2304,6 +2324,42 @@ channel_request_remote_forwarding(u_short listen_port,
        }
 }
 
+/*
+ * Request cancellation of remote forwarding of connection host:port from 
+ * local side.
+ */
+
+void
+channel_request_rforward_cancel(u_short port)
+{
+       int i;
+       const char *address_to_bind = "0.0.0.0";
+
+       if (!compat20)
+               return;
+
+       for (i = 0; i < num_permitted_opens; i++) {
+               if (permitted_opens[i].host_to_connect != NULL && 
+                   permitted_opens[i].listen_port == port)
+                       break;
+       }
+       if (i >= num_permitted_opens) {
+               debug("%s: requested forward not found", __func__);
+               return;
+       }
+       packet_start(SSH2_MSG_GLOBAL_REQUEST);
+       packet_put_cstring("cancel-tcpip-forward");
+       packet_put_char(0);
+       packet_put_cstring(address_to_bind);
+       packet_put_int(port);
+       packet_send();
+
+       permitted_opens[i].listen_port = 0;
+       permitted_opens[i].port_to_connect = 0;
+       free(permitted_opens[i].host_to_connect);
+       permitted_opens[i].host_to_connect = NULL;
+}
+
 /*
  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
  * listening for the port, and sends back a success reply (or disconnect
@@ -2373,7 +2429,8 @@ channel_clear_permitted_opens(void)
        int i;
 
        for (i = 0; i < num_permitted_opens; i++)
-               xfree(permitted_opens[i].host_to_connect);
+               if (permitted_opens[i].host_to_connect != NULL)
+                       xfree(permitted_opens[i].host_to_connect);
        num_permitted_opens = 0;
 
 }
@@ -2441,7 +2498,8 @@ channel_connect_by_listen_address(u_short listen_port)
        int i;
 
        for (i = 0; i < num_permitted_opens; i++)
-               if (permitted_opens[i].listen_port == listen_port)
+               if (permitted_opens[i].host_to_connect != NULL &&
+                   permitted_opens[i].listen_port == listen_port)
                        return connect_to(
                            permitted_opens[i].host_to_connect,
                            permitted_opens[i].port_to_connect);
@@ -2459,7 +2517,8 @@ channel_connect_to(const char *host, u_short port)
        permit = all_opens_permitted;
        if (!permit) {
                for (i = 0; i < num_permitted_opens; i++)
-                       if (permitted_opens[i].port_to_connect == port &&
+                       if (permitted_opens[i].host_to_connect != NULL &&
+                           permitted_opens[i].port_to_connect == port &&
                            strcmp(permitted_opens[i].host_to_connect, host) == 0)
                                permit = 1;
 

diff --git a/channels.h b/channels.h
index 7d981479b1c826d38254d2aaeebee30bb9f98b53..0a49c55ea6b5f1f779b7c76007fd4e75faf00599 100644 (file)
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: channels.h,v 1.71 2003/09/23 20:41:11 markus Exp $    */
+/*     $OpenBSD: channels.h,v 1.72 2004/05/21 11:33:11 djm Exp $       */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -200,8 +200,10 @@ void     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(u_short, const char *, u_short);
+void    channel_request_rforward_cancel(u_short port);
 int     channel_setup_local_fwd_listener(u_short, const char *, u_short, int);
 int     channel_setup_remote_fwd_listener(const char *, u_short, int);
+int     channel_cancel_rport_listener(const char *, u_short);
 
 /* x11 forwarding */
 

diff --git a/clientloop.c b/clientloop.c
index 9cbc1b0ce473656d2a1a72e0ac2df42b07e29806..ce627e8b82418208bd4029053b751b47f09a2401 100644 (file)
--- a/clientloop.c
+++ b/clientloop.c
@@ -59,7 +59,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: clientloop.c,v 1.120 2004/05/20 10:58:05 dtucker Exp $");
+RCSID("$OpenBSD: clientloop.c,v 1.121 2004/05/21 11:33:11 djm Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -506,6 +506,7 @@ process_cmdline(void)
        char *s, *cmd;
        u_short fwd_port, fwd_host_port;
        char buf[1024], sfwd_port[6], sfwd_host_port[6];
+       int delete = 0;
        int local = 0;
 
        leave_raw_mode();
@@ -515,44 +516,77 @@ process_cmdline(void)
                goto out;
        while (*s && isspace(*s))
                s++;
+       if (*s == '-')
+               s++;    /* Skip cmdline '-', if any */
        if (*s == '\0')
                goto out;
-       if (strlen(s) < 2 || s[0] != '-' || !(s[1] == 'L' || s[1] == 'R')) {
+
+       if (*s == '?') {
+               logit("Commands:");
+               logit("      -Lport:host:hostport    Request local forward");
+               logit("      -Rport:host:hostport    Request remote forward");
+               logit("      -KRhostport             Cancel remote forward");
+               goto out;
+       }
+
+       if (*s == 'K') {
+               delete = 1;
+               s++;
+       }
+       if (*s != 'L' && *s != 'R') {
                logit("Invalid command.");
                goto out;
        }
-       if (s[1] == 'L')
+       if (*s == 'L')
                local = 1;
-       if (!local && !compat20) {
+       if (local && delete) {
+               logit("Not supported.");
+               goto out;
+       }
+       if ((!local || delete) && !compat20) {
                logit("Not supported for SSH protocol version 1.");
                goto out;
        }
-       s += 2;
+
+       s++;
        while (*s && isspace(*s))
                s++;
 
-       if (sscanf(s, "%5[0-9]:%255[^:]:%5[0-9]",
-           sfwd_port, buf, sfwd_host_port) != 3 &&
-           sscanf(s, "%5[0-9]/%255[^/]/%5[0-9]",
-           sfwd_port, buf, sfwd_host_port) != 3) {
-               logit("Bad forwarding specification.");
-               goto out;
-       }
-       if ((fwd_port = a2port(sfwd_port)) == 0 ||
-           (fwd_host_port = a2port(sfwd_host_port)) == 0) {
-               logit("Bad forwarding port(s).");
-               goto out;
-       }
-       if (local) {
-               if (channel_setup_local_fwd_listener(fwd_port, buf,
-                   fwd_host_port, options.gateway_ports) < 0) {
-                       logit("Port forwarding failed.");
+       if (delete) {
+               if (sscanf(s, "%5[0-9]", sfwd_host_port) != 1) {
+                       logit("Bad forwarding specification.");
+                       goto out;
+               }
+               if ((fwd_host_port = a2port(sfwd_host_port)) == 0) {
+                       logit("Bad forwarding port(s).");
+                       goto out;
+               }
+               channel_request_rforward_cancel(fwd_host_port);
+       } else {
+               if (sscanf(s, "%5[0-9]:%255[^:]:%5[0-9]",
+                   sfwd_port, buf, sfwd_host_port) != 3 &&
+                   sscanf(s, "%5[0-9]/%255[^/]/%5[0-9]",
+                   sfwd_port, buf, sfwd_host_port) != 3) {
+                       logit("Bad forwarding specification.");
                        goto out;
                }
-       } else
-               channel_request_remote_forwarding(fwd_port, buf,
-                   fwd_host_port);
-       logit("Forwarding port.");
+               if ((fwd_port = a2port(sfwd_port)) == 0 ||
+                   (fwd_host_port = a2port(sfwd_host_port)) == 0) {
+                       logit("Bad forwarding port(s).");
+                       goto out;
+               }
+               if (local) {
+                       if (channel_setup_local_fwd_listener(fwd_port, buf,
+                           fwd_host_port, options.gateway_ports) < 0) {
+                               logit("Port forwarding failed.");
+                               goto out;
+                       }
+               } else
+                       channel_request_remote_forwarding(fwd_port, buf,
+                           fwd_host_port);
+               logit("Forwarding port.");
+       }
+
 out:
        signal(SIGINT, handler);
        enter_raw_mode();

diff --git a/serverloop.c b/serverloop.c
index a777a048d79ead3654aa55733d3bcd6ab09f973d..8d2642d5b7fa048bd6939b9e1d8f5b308c68941a 100644 (file)
--- a/serverloop.c
+++ b/serverloop.c
@@ -35,7 +35,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: serverloop.c,v 1.115 2004/01/19 21:25:15 markus Exp $");
+RCSID("$OpenBSD: serverloop.c,v 1.116 2004/05/21 11:33:11 djm Exp $");
 
 #include "xmalloc.h"
 #include "packet.h"
@@ -991,6 +991,17 @@ server_input_global_request(int type, u_int32_t seq, void *ctxt)
                            listen_address, listen_port, options.gateway_ports);
                }
                xfree(listen_address);
+       } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
+               char *cancel_address;
+               u_short cancel_port;
+
+               cancel_address = packet_get_string(NULL);
+               cancel_port = (u_short)packet_get_int();
+               debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
+                   cancel_address, cancel_port);
+
+               success = channel_cancel_rport_listener(cancel_address,
+                   cancel_port);
        }
        if (want_reply) {
                packet_start(success ?

diff --git a/ssh.1 b/ssh.1
index b7b126440cc80ff4e21a2d71bd2eb7e07697961d..7da143b198d1ad2567c171da374c603096de4d0a 100644 (file)
--- 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 1.185 2004/05/02 11:57:52 dtucker Exp $
+.\" $OpenBSD: ssh.1,v 1.186 2004/05/21 11:33:11 djm Exp $
 .Dd September 25, 1999
 .Dt SSH 1
 .Os
@@ -302,11 +302,18 @@ Display a list of escape characters.
 Send a BREAK to the remote system
 (only useful for SSH protocol version 2 and if the peer supports it).
 .It Cm ~C
-Open command line (only useful for adding port forwardings using the
+Open command line.
+Currently this allows the addition of port forwardings using the
 .Fl L
 and
 .Fl R
-options).
+options (see below).
+It also allows the cancellation of existing remote port-forwardings 
+using
+.Fl KR Ar hostport .
+Basic help is available, using the 
+.Fl ?
+option.
 .It Cm ~R
 Request rekeying of the connection
 (only useful for SSH protocol version 2 and if the peer supports it).