upstream commit

Expose devices allocated for tun/tap forwarding.

At the client, the device may be obtained from a new %T expansion
for LocalCommand.

At the server, the allocated devices will be listed in a
SSH_TUNNEL variable exposed to the environment of any user sessions
started after the tunnel forwarding was established.

ok markus

Upstream-ID: e61e53f8ae80566e9ddc0d67a5df5bdf2f3c9f9e

1 files changed, 20 insertions, 2 deletions

diff --git a/serverloop.c b/serverloop.c
index 24bbae322..a3cb8e782 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.198 2017/09/12 06:35:32 djm Exp $ */
+/* $OpenBSD: serverloop.c,v 1.199 2017/10/23 05:08:00 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -99,6 +99,9 @@ static volatile sig_atomic_t received_sigterm = 0;
 /* prototypes */
 static void server_init_dispatch(void);
 
+/* requested tunnel forwarding interface(s), shared with session.c */
+char *tun_fwd_ifnames = NULL;
+
 /*
  * we write to this pipe if a SIGCHLD is caught in order to avoid
  * the race between select() and child_terminated
@@ -519,6 +522,7 @@ server_request_tun(struct ssh *ssh)
         Channel *c = NULL;
         int mode, tun;
         int sock;
+        char *tmp, *ifname = NULL;
 
         mode = packet_get_int();
         switch (mode) {
@@ -541,9 +545,10 @@ server_request_tun(struct ssh *ssh)
                         goto done;
                 tun = forced_tun_device;
         }
-        sock = tun_open(tun, mode);
+        sock = tun_open(tun, mode, &ifname);
         if (sock < 0)
                 goto done;
+        debug("Tunnel forwarding using interface %s", ifname);
         c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1,
             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
         c->datagram = 1;
@@ -553,6 +558,19 @@ server_request_tun(struct ssh *ssh)
                     sys_tun_outfilter, NULL, NULL);
 #endif
 
+        /*
+         * Update the list of names exposed to the session
+         * XXX remove these if the tunnels are closed (won't matter
+         * much if they are already in the environment though)
+         */
+        tmp = tun_fwd_ifnames;
+        xasprintf(&tun_fwd_ifnames, "%s%s%s",
+            tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames,
+            tun_fwd_ifnames == NULL ? "" : ",",
+            ifname);
+        free(tmp);
+        free(ifname);
+
  done:
         if (c == NULL)
                 packet_send_debug("Failed to open the tunnel device.");