[openssh-commits] [openssh] 01/01: upstream commit
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Sat Oct 1 03:30:23 AEST 2016
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djm pushed a commit to branch master
in repository openssh.
commit 8d0578478586e283e751ca51e7b0690631da139a
Author: markus at openbsd.org <markus at openbsd.org>
Date: Fri Sep 30 09:19:13 2016 +0000
upstream commit
ssh proxy mux mode (-O proxy; idea from Simon Tatham): - mux
client speaks the ssh-packet protocol directly over unix-domain socket. - mux
server acts as a proxy, translates channel IDs and relays to the server. - no
filedescriptor passing necessary. - combined with unix-domain forwarding it's
even possible to run mux client and server on different machines. feedback
& ok djm@
Upstream-ID: 666a2fb79f58e5c50e246265fb2b9251e505c25b
---
channels.c | 392 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
channels.h | 12 +-
clientloop.c | 45 ++++++-
clientloop.h | 5 +-
mux.c | 69 +++++++++--
opacket.h | 4 +
packet.c | 93 +++++++++++++-
packet.h | 6 +-
ssh.c | 27 ++--
9 files changed, 612 insertions(+), 41 deletions(-)
diff --git a/channels.c b/channels.c
index 5d8c2a0..ae24841 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.353 2016/09/19 07:52:42 natano Exp $ */
+/* $OpenBSD: channels.c,v 1.354 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -71,6 +71,7 @@
#include "ssh.h"
#include "ssh1.h"
#include "ssh2.h"
+#include "ssherr.h"
#include "packet.h"
#include "log.h"
#include "misc.h"
@@ -120,6 +121,7 @@ typedef struct {
char *listen_host; /* Remote side should listen address. */
char *listen_path; /* Remote side should listen path. */
int listen_port; /* Remote side should listen port. */
+ Channel *downstream; /* Downstream mux*/
} ForwardPermission;
/* List of all permitted host/port pairs to connect by the user. */
@@ -183,6 +185,7 @@ static int IPv4or6 = AF_UNSPEC;
/* helper */
static void port_open_helper(Channel *c, char *rtype);
+static const char *channel_rfwd_bind_host(const char *listen_host);
/* non-blocking connect helpers */
static int connect_next(struct channel_connect *);
@@ -207,6 +210,20 @@ channel_by_id(int id)
return c;
}
+Channel *
+channel_by_remote_id(int remote_id)
+{
+ Channel *c;
+ u_int i;
+
+ for (i = 0; i < channels_alloc; i++) {
+ c = channels[i];
+ if (c != NULL && c->remote_id == remote_id)
+ return c;
+ }
+ return NULL;
+}
+
/*
* Returns the channel if it is allowed to receive protocol messages.
* Private channels, like listening sockets, may not receive messages.
@@ -229,6 +246,7 @@ channel_lookup(int id)
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
case SSH_CHANNEL_ABANDONED:
+ case SSH_CHANNEL_MUX_PROXY:
return (c);
}
logit("Non-public channel %d, type %d.", id, c->type);
@@ -410,14 +428,56 @@ channel_free(Channel *c)
{
char *s;
u_int i, n;
+ Channel *other;
struct channel_confirm *cc;
- for (n = 0, i = 0; i < channels_alloc; i++)
- if (channels[i])
+ for (n = 0, i = 0; i < channels_alloc; i++) {
+ if ((other = channels[i]) != NULL) {
n++;
+
+ /* detach from mux client and prepare for closing */
+ if (c->type == SSH_CHANNEL_MUX_CLIENT &&
+ other->type == SSH_CHANNEL_MUX_PROXY &&
+ other->mux_ctx == c) {
+ other->mux_ctx = NULL;
+ other->type = SSH_CHANNEL_OPEN;
+ other->istate = CHAN_INPUT_CLOSED;
+ other->ostate = CHAN_OUTPUT_CLOSED;
+ }
+ }
+ }
debug("channel %d: free: %s, nchannels %u", c->self,
c->remote_name ? c->remote_name : "???", n);
+ /* XXX more MUX cleanup: remove remote forwardings */
+ if (c->type == SSH_CHANNEL_MUX_CLIENT) {
+ for (i = 0; i < (u_int)num_permitted_opens; i++) {
+ if (permitted_opens[i].downstream != c)
+ continue;
+ /* cancel on the server, since mux client is gone */
+ debug("channel %d: cleanup remote forward for %s:%u",
+ c->self,
+ permitted_opens[i].listen_host,
+ permitted_opens[i].listen_port);
+ packet_start(SSH2_MSG_GLOBAL_REQUEST);
+ packet_put_cstring("cancel-tcpip-forward");
+ packet_put_char(0);
+ packet_put_cstring(channel_rfwd_bind_host(
+ permitted_opens[i].listen_host));
+ packet_put_int(permitted_opens[i].listen_port);
+ packet_send();
+ /* unregister */
+ 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;
+ free(permitted_opens[i].listen_host);
+ permitted_opens[i].listen_host = NULL;
+ permitted_opens[i].listen_path = NULL;
+ permitted_opens[i].downstream = NULL;
+ }
+ }
+
s = channel_open_message();
debug3("channel %d: status: %s", c->self, s);
free(s);
@@ -563,6 +623,7 @@ channel_still_open(void)
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_MUX_CLIENT:
+ case SSH_CHANNEL_MUX_PROXY:
return 1;
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
@@ -596,6 +657,7 @@ channel_find_open(void)
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_MUX_LISTENER:
case SSH_CHANNEL_MUX_CLIENT:
+ case SSH_CHANNEL_MUX_PROXY:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
@@ -621,7 +683,6 @@ channel_find_open(void)
return -1;
}
-
/*
* Returns a message describing the currently open forwarded connections,
* suitable for sending to the client. The message contains crlf pairs for
@@ -650,7 +711,6 @@ channel_open_message(void)
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_ZOMBIE:
case SSH_CHANNEL_ABANDONED:
- case SSH_CHANNEL_MUX_CLIENT:
case SSH_CHANNEL_MUX_LISTENER:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
@@ -663,6 +723,8 @@ channel_open_message(void)
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
+ case SSH_CHANNEL_MUX_PROXY:
+ case SSH_CHANNEL_MUX_CLIENT:
snprintf(buf, sizeof buf,
" #%d %.300s (t%d r%d i%u/%d o%u/%d fd %d/%d cc %d)\r\n",
c->self, c->remote_name,
@@ -2360,6 +2422,278 @@ channel_output_poll(void)
}
}
+/* -- mux proxy support */
+
+/*
+ * When multiplexing channel messages for mux clients we have to deal
+ * with downstream messages from the mux client and upstream messages
+ * from the ssh server:
+ * 1) Handling downstream messages is straightforward and happens
+ * in channel_proxy_downstream():
+ * - We forward all messages (mostly) unmodified to the server.
+ * - However, in order to route messages from upstream to the correct
+ * downstream client, we have to replace the channel IDs used by the
+ * mux clients with a unique channel ID because the mux clients might
+ * use conflicting channel IDs.
+ * - so we inspect and change both SSH2_MSG_CHANNEL_OPEN and
+ * SSH2_MSG_CHANNEL_OPEN_CONFIRMATION messages, create a local
+ * SSH_CHANNEL_MUX_PROXY channel and replace the mux clients ID
+ * with the newly allocated channel ID.
+ * 2) Upstream messages are received by matching SSH_CHANNEL_MUX_PROXY
+ * channels and procesed by channel_proxy_upstream(). The local channel ID
+ * is then translated back to the original mux client ID.
+ * 3) In both cases we need to keep track of matching SSH2_MSG_CHANNEL_CLOSE
+ * messages so we can clean up SSH_CHANNEL_MUX_PROXY channels.
+ * 4) The SSH_CHANNEL_MUX_PROXY channels also need to closed when the
+ * downstream mux client are removed.
+ * 5) Handling SSH2_MSG_CHANNEL_OPEN messages from the upstream server
+ * requires more work, because they are not addressed to a specific
+ * channel. E.g. client_request_forwarded_tcpip() needs to figure
+ * out whether the request is addressed to the local client or a
+ * specific downstream client based on the listen-address/port.
+ * 6) Agent and X11-Forwarding have a similar problem and are currenly
+ * not supported as the matching session/channel cannot be identified
+ * easily.
+ */
+
+/*
+ * receive packets from downstream mux clients:
+ * channel callback fired on read from mux client, creates
+ * SSH_CHANNEL_MUX_PROXY channels and translates channel IDs
+ * on channel creation.
+ */
+int
+channel_proxy_downstream(Channel *downstream)
+{
+ Channel *c = NULL;
+ struct ssh *ssh = active_state;
+ struct sshbuf *original = NULL, *modified = NULL;
+ const u_char *cp;
+ char *ctype = NULL, *listen_host = NULL;
+ u_char type;
+ size_t have;
+ int ret = -1, r, id, remote_id, listen_port, idx;
+
+ /* sshbuf_dump(&downstream->input, stderr); */
+ if ((r = sshbuf_get_string_direct(&downstream->input, &cp, &have))
+ != 0) {
+ error("%s: malformed message: %s", __func__, ssh_err(r));
+ return -1;
+ }
+ if (have < 2) {
+ error("%s: short message", __func__);
+ return -1;
+ }
+ type = cp[1];
+ /* skip padlen + type */
+ cp += 2;
+ have -= 2;
+ if (ssh_packet_log_type(type))
+ debug3("%s: channel %u: down->up: type %u", __func__,
+ downstream->self, type);
+
+ switch (type) {
+ case SSH2_MSG_CHANNEL_OPEN:
+ if ((original = sshbuf_from(cp, have)) == NULL ||
+ (modified = sshbuf_new()) == NULL) {
+ error("%s: alloc", __func__);
+ goto out;
+ }
+ if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 ||
+ (r = sshbuf_get_u32(original, &id)) != 0) {
+ error("%s: parse error %s", __func__, ssh_err(r));
+ goto out;
+ }
+ c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
+ -1, -1, -1, 0, 0, 0, ctype, 1);
+ c->mux_ctx = downstream; /* point to mux client */
+ c->mux_downstream_id = id; /* original downstream id */
+ if ((r = sshbuf_put_cstring(modified, ctype)) != 0 ||
+ (r = sshbuf_put_u32(modified, c->self)) != 0 ||
+ (r = sshbuf_putb(modified, original)) != 0) {
+ error("%s: compose error %s", __func__, ssh_err(r));
+ channel_free(c);
+ goto out;
+ }
+ break;
+ case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
+ /*
+ * Almost the same as SSH2_MSG_CHANNEL_OPEN, except then we
+ * need to parse 'remote_id' instead of 'ctype'.
+ */
+ if ((original = sshbuf_from(cp, have)) == NULL ||
+ (modified = sshbuf_new()) == NULL) {
+ error("%s: alloc", __func__);
+ goto out;
+ }
+ if ((r = sshbuf_get_u32(original, &remote_id)) != 0 ||
+ (r = sshbuf_get_u32(original, &id)) != 0) {
+ error("%s: parse error %s", __func__, ssh_err(r));
+ goto out;
+ }
+ c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
+ -1, -1, -1, 0, 0, 0, "mux-down-connect", 1);
+ c->mux_ctx = downstream; /* point to mux client */
+ c->mux_downstream_id = id;
+ c->remote_id = remote_id;
+ if ((r = sshbuf_put_u32(modified, remote_id)) != 0 ||
+ (r = sshbuf_put_u32(modified, c->self)) != 0 ||
+ (r = sshbuf_putb(modified, original)) != 0) {
+ error("%s: compose error %s", __func__, ssh_err(r));
+ channel_free(c);
+ goto out;
+ }
+ break;
+ case SSH2_MSG_GLOBAL_REQUEST:
+ if ((original = sshbuf_from(cp, have)) == NULL) {
+ error("%s: alloc", __func__);
+ goto out;
+ }
+ if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) {
+ error("%s: parse error %s", __func__, ssh_err(r));
+ goto out;
+ }
+ if (strcmp(ctype, "tcpip-forward") != 0) {
+ error("%s: unsupported request %s", __func__, ctype);
+ goto out;
+ }
+ if ((r = sshbuf_get_u8(original, NULL)) != 0 ||
+ (r = sshbuf_get_cstring(original, &listen_host, NULL)) != 0 ||
+ (r = sshbuf_get_u32(original, &listen_port)) != 0) {
+ error("%s: parse error %s", __func__, ssh_err(r));
+ goto out;
+ }
+ /* Record that connection to this host/port is permitted. */
+ permitted_opens = xreallocarray(permitted_opens,
+ num_permitted_opens + 1, sizeof(*permitted_opens));
+ idx = num_permitted_opens++;
+ permitted_opens[idx].host_to_connect = xstrdup("<mux>");
+ permitted_opens[idx].port_to_connect = -1;
+ permitted_opens[idx].listen_host = listen_host;
+ permitted_opens[idx].listen_port = listen_port;
+ permitted_opens[idx].downstream = downstream;
+ listen_host = NULL;
+ break;
+ case SSH2_MSG_CHANNEL_CLOSE:
+ if (have < 4)
+ break;
+ remote_id = PEEK_U32(cp);
+ if ((c = channel_by_remote_id(remote_id)) != NULL) {
+ if (c->flags & CHAN_CLOSE_RCVD)
+ channel_free(c);
+ else
+ c->flags |= CHAN_CLOSE_SENT;
+ }
+ break;
+ }
+ if (modified) {
+ if ((r = sshpkt_start(ssh, type)) != 0 ||
+ (r = sshpkt_putb(ssh, modified)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0) {
+ error("%s: send %s", __func__, ssh_err(r));
+ goto out;
+ }
+ } else {
+ if ((r = sshpkt_start(ssh, type)) != 0 ||
+ (r = sshpkt_put(ssh, cp, have)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0) {
+ error("%s: send %s", __func__, ssh_err(r));
+ goto out;
+ }
+ }
+ ret = 0;
+ out:
+ free(ctype);
+ free(listen_host);
+ sshbuf_free(original);
+ sshbuf_free(modified);
+ return ret;
+}
+
+/*
+ * receive packets from upstream server and de-multiplex packets
+ * to correct downstream:
+ * implemented as a helper for channel input handlers,
+ * replaces local (proxy) channel ID with downstream channel ID.
+ */
+int
+channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
+{
+ struct ssh *ssh = active_state;
+ struct sshbuf *b = NULL;
+ Channel *downstream;
+ const u_char *cp = NULL;
+ size_t len;
+ int r;
+
+ /*
+ * When receiving packets from the peer we need to check whether we
+ * need to forward the packets to the mux client. In this case we
+ * restore the orignal channel id and keep track of CLOSE messages,
+ * so we can cleanup the channel.
+ */
+ if (c == NULL || c->type != SSH_CHANNEL_MUX_PROXY)
+ return 0;
+ if ((downstream = c->mux_ctx) == NULL)
+ return 0;
+ switch (type) {
+ case SSH2_MSG_CHANNEL_CLOSE:
+ case SSH2_MSG_CHANNEL_DATA:
+ case SSH2_MSG_CHANNEL_EOF:
+ case SSH2_MSG_CHANNEL_EXTENDED_DATA:
+ case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
+ case SSH2_MSG_CHANNEL_OPEN_FAILURE:
+ case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
+ case SSH2_MSG_CHANNEL_SUCCESS:
+ case SSH2_MSG_CHANNEL_FAILURE:
+ case SSH2_MSG_CHANNEL_REQUEST:
+ break;
+ default:
+ debug2("%s: channel %u: unsupported type %u", __func__,
+ c->self, type);
+ return 0;
+ }
+ if ((b = sshbuf_new()) == NULL) {
+ error("%s: alloc reply", __func__);
+ goto out;
+ }
+ /* get remaining payload (after id) */
+ cp = sshpkt_ptr(ssh, &len);
+ if (cp == NULL) {
+ error("%s: no packet", __func__);
+ goto out;
+ }
+ /* translate id and send to muxclient */
+ if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
+ (r = sshbuf_put_u8(b, type)) != 0 ||
+ (r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 ||
+ (r = sshbuf_put(b, cp, len)) != 0 ||
+ (r = sshbuf_put_stringb(&downstream->output, b)) != 0) {
+ error("%s: compose for muxclient %s", __func__, ssh_err(r));
+ goto out;
+ }
+ /* sshbuf_dump(b, stderr); */
+ if (ssh_packet_log_type(type))
+ debug3("%s: channel %u: up->down: type %u", __func__, c->self,
+ type);
+ out:
+ /* update state */
+ switch (type) {
+ case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
+ /* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
+ if (cp && len > 4)
+ c->remote_id = PEEK_U32(cp);
+ break;
+ case SSH2_MSG_CHANNEL_CLOSE:
+ if (c->flags & CHAN_CLOSE_SENT)
+ channel_free(c);
+ else
+ c->flags |= CHAN_CLOSE_RCVD;
+ break;
+ }
+ sshbuf_free(b);
+ return 1;
+}
/* -- protocol input */
@@ -2377,6 +2711,8 @@ channel_input_data(int type, u_int32_t seq, void *ctxt)
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received data for nonexistent channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
/* Ignore any data for non-open channels (might happen on close) */
if (c->type != SSH_CHANNEL_OPEN &&
@@ -2439,6 +2775,8 @@ channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
if (c == NULL)
packet_disconnect("Received extended_data for bad channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
if (c->type != SSH_CHANNEL_OPEN) {
logit("channel %d: ext data for non open", id);
return 0;
@@ -2484,6 +2822,8 @@ channel_input_ieof(int type, u_int32_t seq, void *ctxt)
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received ieof for nonexistent channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
chan_rcvd_ieof(c);
/* XXX force input close */
@@ -2508,7 +2848,8 @@ channel_input_close(int type, u_int32_t seq, void *ctxt)
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received close for nonexistent channel %d.", id);
-
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
/*
* Send a confirmation that we have closed the channel and no more
* data is coming for it.
@@ -2543,9 +2884,11 @@ channel_input_oclose(int type, u_int32_t seq, void *ctxt)
int id = packet_get_int();
Channel *c = channel_lookup(id);
- packet_check_eom();
if (c == NULL)
packet_disconnect("Received oclose for nonexistent channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
+ packet_check_eom();
chan_rcvd_oclose(c);
return 0;
}
@@ -2557,10 +2900,12 @@ channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
int id = packet_get_int();
Channel *c = channel_lookup(id);
- packet_check_eom();
if (c == NULL)
packet_disconnect("Received close confirmation for "
"out-of-range channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
+ packet_check_eom();
if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
packet_disconnect("Received close confirmation for "
"non-closed channel %d (type %d).", id, c->type);
@@ -2578,7 +2923,12 @@ channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
id = packet_get_int();
c = channel_lookup(id);
- if (c==NULL || c->type != SSH_CHANNEL_OPENING)
+ if (c==NULL)
+ packet_disconnect("Received open confirmation for "
+ "unknown channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
+ if (c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open confirmation for "
"non-opening channel %d.", id);
remote_id = packet_get_int();
@@ -2628,7 +2978,12 @@ channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
id = packet_get_int();
c = channel_lookup(id);
- if (c==NULL || c->type != SSH_CHANNEL_OPENING)
+ if (c==NULL)
+ packet_disconnect("Received open failure for "
+ "unknown channel %d.", id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
+ if (c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open failure for "
"non-opening channel %d.", id);
if (compat20) {
@@ -2672,6 +3027,8 @@ channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
logit("Received window adjust for non-open channel %d.", id);
return 0;
}
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
adjust = packet_get_int();
packet_check_eom();
debug2("channel %d: rcvd adjust %u", id, adjust);
@@ -2726,14 +3083,15 @@ channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
packet_set_alive_timeouts(0);
id = packet_get_int();
- packet_check_eom();
-
debug2("channel_input_status_confirm: type %d id %d", type, id);
if ((c = channel_lookup(id)) == NULL) {
logit("channel_input_status_confirm: %d: unknown", id);
return 0;
}
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
+ packet_check_eom();
if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
return 0;
cc->cb(type, c, cc->ctx);
@@ -3287,6 +3645,7 @@ channel_request_remote_forwarding(struct Forward *fwd)
permitted_opens[idx].listen_path = NULL;
permitted_opens[idx].listen_port = fwd->listen_port;
}
+ permitted_opens[idx].downstream = NULL;
}
return (idx);
}
@@ -3382,6 +3741,7 @@ channel_request_rforward_cancel_tcpip(const char *host, u_short port)
free(permitted_opens[i].listen_host);
permitted_opens[i].listen_host = NULL;
permitted_opens[i].listen_path = NULL;
+ permitted_opens[i].downstream = NULL;
return 0;
}
@@ -3419,6 +3779,7 @@ channel_request_rforward_cancel_streamlocal(const char *path)
permitted_opens[i].listen_host = NULL;
free(permitted_opens[i].listen_path);
permitted_opens[i].listen_path = NULL;
+ permitted_opens[i].downstream = NULL;
return 0;
}
@@ -3501,6 +3862,7 @@ channel_add_permitted_opens(char *host, int port)
permitted_opens[num_permitted_opens].listen_host = NULL;
permitted_opens[num_permitted_opens].listen_path = NULL;
permitted_opens[num_permitted_opens].listen_port = 0;
+ permitted_opens[num_permitted_opens].downstream = NULL;
num_permitted_opens++;
all_opens_permitted = 0;
@@ -3763,6 +4125,10 @@ connect_to(const char *name, int port, char *ctype, char *rname)
return c;
}
+/*
+ * returns either the newly connected channel or the downstream channel
+ * that needs to deal with this connection.
+ */
Channel *
channel_connect_by_listen_address(const char *listen_host,
u_short listen_port, char *ctype, char *rname)
@@ -3772,6 +4138,8 @@ channel_connect_by_listen_address(const char *listen_host,
for (i = 0; i < num_permitted_opens; i++) {
if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
listen_port, 1)) {
+ if (permitted_opens[i].downstream)
+ return permitted_opens[i].downstream;
return connect_to(
permitted_opens[i].host_to_connect,
permitted_opens[i].port_to_connect, ctype, rname);
diff --git a/channels.h b/channels.h
index 9d76c9d..95363e9 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.h,v 1.118 2015/07/01 02:26:31 djm Exp $ */
+/* $OpenBSD: channels.h,v 1.119 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -58,7 +58,8 @@
#define SSH_CHANNEL_ABANDONED 17 /* Abandoned session, eg mux */
#define SSH_CHANNEL_UNIX_LISTENER 18 /* Listening on a domain socket. */
#define SSH_CHANNEL_RUNIX_LISTENER 19 /* Listening to a R-style domain socket. */
-#define SSH_CHANNEL_MAX_TYPE 20
+#define SSH_CHANNEL_MUX_PROXY 20 /* proxy channel for mux-slave */
+#define SSH_CHANNEL_MAX_TYPE 21
#define CHANNEL_CANCEL_PORT_STATIC -1
@@ -162,6 +163,7 @@ struct Channel {
mux_callback_fn *mux_rcb;
void *mux_ctx;
int mux_pause;
+ int mux_downstream_id;
};
#define CHAN_EXTENDED_IGNORE 0
@@ -209,6 +211,7 @@ struct Channel {
/* channel management */
Channel *channel_by_id(int);
+Channel *channel_by_remote_id(int);
Channel *channel_lookup(int);
Channel *channel_new(char *, int, int, int, int, u_int, u_int, int, char *, int);
void channel_set_fds(int, int, int, int, int, int, int, u_int);
@@ -228,6 +231,11 @@ void channel_cancel_cleanup(int);
int channel_close_fd(int *);
void channel_send_window_changes(void);
+/* mux proxy support */
+
+int channel_proxy_downstream(Channel *mc);
+int channel_proxy_upstream(Channel *, int, u_int32_t, void *);
+
/* protocol handler */
int channel_input_close(int, u_int32_t, void *);
diff --git a/clientloop.c b/clientloop.c
index 58e7122..4289a40 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.288 2016/09/17 18:00:27 tedu Exp $ */
+/* $OpenBSD: clientloop.c,v 1.289 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -1883,11 +1883,14 @@ client_input_agent_open(int type, u_int32_t seq, void *ctxt)
}
static Channel *
-client_request_forwarded_tcpip(const char *request_type, int rchan)
+client_request_forwarded_tcpip(const char *request_type, int rchan,
+ u_int rwindow, u_int rmaxpack)
{
Channel *c = NULL;
+ struct sshbuf *b = NULL;
char *listen_address, *originator_address;
u_short listen_port, originator_port;
+ int r;
/* Get rest of the packet */
listen_address = packet_get_string(NULL);
@@ -1902,6 +1905,31 @@ client_request_forwarded_tcpip(const char *request_type, int rchan)
c = channel_connect_by_listen_address(listen_address, listen_port,
"forwarded-tcpip", originator_address);
+ if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
+ if ((b = sshbuf_new()) == NULL) {
+ error("%s: alloc reply", __func__);
+ goto out;
+ }
+ /* reconstruct and send to muxclient */
+ if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
+ (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
+ (r = sshbuf_put_cstring(b, request_type)) != 0 ||
+ (r = sshbuf_put_u32(b, rchan)) != 0 ||
+ (r = sshbuf_put_u32(b, rwindow)) != 0 ||
+ (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
+ (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
+ (r = sshbuf_put_u32(b, listen_port)) != 0 ||
+ (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
+ (r = sshbuf_put_u32(b, originator_port)) != 0 ||
+ (r = sshbuf_put_stringb(&c->output, b)) != 0) {
+ error("%s: compose for muxclient %s", __func__,
+ ssh_err(r));
+ goto out;
+ }
+ }
+
+ out:
+ sshbuf_free(b);
free(originator_address);
free(listen_address);
return c;
@@ -2057,7 +2085,8 @@ client_input_channel_open(int type, u_int32_t seq, void *ctxt)
ctype, rchan, rwindow, rmaxpack);
if (strcmp(ctype, "forwarded-tcpip") == 0) {
- c = client_request_forwarded_tcpip(ctype, rchan);
+ c = client_request_forwarded_tcpip(ctype, rchan, rwindow,
+ rmaxpack);
} else if (strcmp(ctype, "forwarded-streamlocal at openssh.com") == 0) {
c = client_request_forwarded_streamlocal(ctype, rchan);
} else if (strcmp(ctype, "x11") == 0) {
@@ -2065,8 +2094,9 @@ client_input_channel_open(int type, u_int32_t seq, void *ctxt)
} else if (strcmp(ctype, "auth-agent at openssh.com") == 0) {
c = client_request_agent(ctype, rchan);
}
-/* XXX duplicate : */
- if (c != NULL) {
+ if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
+ debug3("proxied to downstream: %s", ctype);
+ } else if (c != NULL) {
debug("confirm %s", ctype);
c->remote_id = rchan;
c->remote_window = rwindow;
@@ -2102,6 +2132,9 @@ client_input_channel_req(int type, u_int32_t seq, void *ctxt)
char *rtype;
id = packet_get_int();
+ c = channel_lookup(id);
+ if (channel_proxy_upstream(c, type, seq, ctxt))
+ return 0;
rtype = packet_get_string(NULL);
reply = packet_get_char();
@@ -2110,7 +2143,7 @@ client_input_channel_req(int type, u_int32_t seq, void *ctxt)
if (id == -1) {
error("client_input_channel_req: request for channel -1");
- } else if ((c = channel_lookup(id)) == NULL) {
+ } else if (c == NULL) {
error("client_input_channel_req: channel %d: "
"unknown channel", id);
} else if (strcmp(rtype, "eow at openssh.com") == 0) {
diff --git a/clientloop.h b/clientloop.h
index f4d4c69..ae83aa8 100644
--- a/clientloop.h
+++ b/clientloop.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.h,v 1.32 2016/01/13 23:04:47 djm Exp $ */
+/* $OpenBSD: clientloop.h,v 1.33 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -71,9 +71,10 @@ void client_expect_confirm(int, const char *, enum confirm_action);
#define SSHMUX_COMMAND_FORWARD 5 /* Forward only, no command */
#define SSHMUX_COMMAND_STOP 6 /* Disable mux but not conn */
#define SSHMUX_COMMAND_CANCEL_FWD 7 /* Cancel forwarding(s) */
+#define SSHMUX_COMMAND_PROXY 8 /* Open new connection */
void muxserver_listen(void);
-void muxclient(const char *);
+int muxclient(const char *);
void mux_exit_message(Channel *, int);
void mux_tty_alloc_failed(Channel *);
diff --git a/mux.c b/mux.c
index a8a753b..ec42bf5 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.61 2016/08/08 22:40:57 dtucker Exp $ */
+/* $OpenBSD: mux.c,v 1.62 2016/09/30 09:19:13 markus Exp $ */
/*
* Copyright (c) 2002-2008 Damien Miller <djm at openbsd.org>
*
@@ -79,6 +79,7 @@
#include "key.h"
#include "readconf.h"
#include "clientloop.h"
+#include "ssherr.h"
/* from ssh.c */
extern int tty_flag;
@@ -144,6 +145,7 @@ struct mux_master_state {
#define MUX_C_CLOSE_FWD 0x10000007
#define MUX_C_NEW_STDIO_FWD 0x10000008
#define MUX_C_STOP_LISTENING 0x10000009
+#define MUX_C_PROXY 0x1000000f
#define MUX_S_OK 0x80000001
#define MUX_S_PERMISSION_DENIED 0x80000002
#define MUX_S_FAILURE 0x80000003
@@ -152,6 +154,7 @@ struct mux_master_state {
#define MUX_S_SESSION_OPENED 0x80000006
#define MUX_S_REMOTE_PORT 0x80000007
#define MUX_S_TTY_ALLOC_FAIL 0x80000008
+#define MUX_S_PROXY 0x8000000f
/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
#define MUX_FWD_LOCAL 1
@@ -169,6 +172,7 @@ static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *);
static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *);
static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *);
static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *);
+static int process_mux_proxy(u_int, Channel *, Buffer *, Buffer *);
static const struct {
u_int type;
@@ -182,6 +186,7 @@ static const struct {
{ MUX_C_CLOSE_FWD, process_mux_close_fwd },
{ MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
{ MUX_C_STOP_LISTENING, process_mux_stop_listening },
+ { MUX_C_PROXY, process_mux_proxy },
{ 0, NULL }
};
@@ -1110,6 +1115,18 @@ process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
return 0;
}
+static int
+process_mux_proxy(u_int rid, Channel *c, Buffer *m, Buffer *r)
+{
+ debug("%s: channel %d: proxy request", __func__, c->self);
+
+ c->mux_rcb = channel_proxy_downstream;
+ buffer_put_int(r, MUX_S_PROXY);
+ buffer_put_int(r, rid);
+
+ return 0;
+}
+
/* Channel callbacks fired on read/write from mux slave fd */
static int
mux_master_read_cb(Channel *c)
@@ -1960,6 +1977,41 @@ mux_client_request_session(int fd)
}
static int
+mux_client_proxy(int fd)
+{
+ Buffer m;
+ char *e;
+ u_int type, rid;
+
+ buffer_init(&m);
+ buffer_put_int(&m, MUX_C_PROXY);
+ buffer_put_int(&m, muxclient_request_id);
+ if (mux_client_write_packet(fd, &m) != 0)
+ fatal("%s: write packet: %s", __func__, strerror(errno));
+
+ buffer_clear(&m);
+
+ /* Read their reply */
+ if (mux_client_read_packet(fd, &m) != 0) {
+ buffer_free(&m);
+ return 0;
+ }
+ type = buffer_get_int(&m);
+ if (type != MUX_S_PROXY) {
+ e = buffer_get_string(&m, NULL);
+ fatal("%s: master returned error: %s", __func__, e);
+ }
+ if ((rid = buffer_get_int(&m)) != muxclient_request_id)
+ fatal("%s: out of sequence reply: my id %u theirs %u",
+ __func__, muxclient_request_id, rid);
+ buffer_free(&m);
+
+ debug3("%s: done", __func__);
+ muxclient_request_id++;
+ return 0;
+}
+
+static int
mux_client_request_stdio_fwd(int fd)
{
Buffer m;
@@ -2105,7 +2157,7 @@ mux_client_request_stop_listening(int fd)
}
/* Multiplex client main loop. */
-void
+int
muxclient(const char *path)
{
struct sockaddr_un addr;
@@ -2128,7 +2180,7 @@ muxclient(const char *path)
case SSHCTL_MASTER_NO:
break;
default:
- return;
+ return -1;
}
memset(&addr, '\0', sizeof(addr));
@@ -2164,14 +2216,14 @@ muxclient(const char *path)
strerror(errno));
}
close(sock);
- return;
+ return -1;
}
set_nonblock(sock);
if (mux_client_hello_exchange(sock) != 0) {
error("%s: master hello exchange failed", __func__);
close(sock);
- return;
+ return -1;
}
switch (muxclient_command) {
@@ -2191,10 +2243,10 @@ muxclient(const char *path)
case SSHMUX_COMMAND_OPEN:
if (mux_client_forwards(sock, 0) != 0) {
error("%s: master forward request failed", __func__);
- return;
+ return -1;
}
mux_client_request_session(sock);
- return;
+ return -1;
case SSHMUX_COMMAND_STDIO_FWD:
mux_client_request_stdio_fwd(sock);
exit(0);
@@ -2207,6 +2259,9 @@ muxclient(const char *path)
error("%s: master cancel forward request failed",
__func__);
exit(0);
+ case SSHMUX_COMMAND_PROXY:
+ mux_client_proxy(sock);
+ return (sock);
default:
fatal("unrecognised muxclient_command %d", muxclient_command);
}
diff --git a/opacket.h b/opacket.h
index d2a63a3..c487f4f 100644
--- a/opacket.h
+++ b/opacket.h
@@ -153,5 +153,9 @@ void packet_disconnect(const char *, ...)
ssh_packet_set_rekey_limits(active_state, x, y)
#define packet_get_bytes(x,y) \
ssh_packet_get_bytes(active_state, x, y)
+#define packet_set_mux() \
+ ssh_packet_set_mux(active_state)
+#define packet_get_mux() \
+ ssh_packet_get_mux(active_state)
#endif /* _OPACKET_H */
diff --git a/packet.c b/packet.c
index 50de026..783ae5b 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.241 2016/09/28 21:44:52 djm Exp $ */
+/* $OpenBSD: packet.c,v 1.242 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -204,6 +204,9 @@ struct session_state {
/* Used in packet_send2 */
int rekeying;
+ /* Used in ssh_packet_send_mux() */
+ int mux;
+
/* Used in packet_set_interactive */
int set_interactive_called;
@@ -325,6 +328,19 @@ ssh_packet_set_timeout(struct ssh *ssh, int timeout, int count)
state->packet_timeout_ms = timeout * count * 1000;
}
+void
+ssh_packet_set_mux(struct ssh *ssh)
+{
+ ssh->state->mux = 1;
+ ssh->state->rekeying = 0;
+}
+
+int
+ssh_packet_get_mux(struct ssh *ssh)
+{
+ return ssh->state->mux;
+}
+
int
ssh_packet_stop_discard(struct ssh *ssh)
{
@@ -1078,7 +1094,7 @@ ssh_packet_enable_delayed_compress(struct ssh *ssh)
}
/* Used to mute debug logging for noisy packet types */
-static int
+int
ssh_packet_log_type(u_char type)
{
switch (type) {
@@ -1623,6 +1639,44 @@ ssh_packet_read_poll1(struct ssh *ssh, u_char *typep)
return r;
}
+static int
+ssh_packet_read_poll2_mux(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
+{
+ struct session_state *state = ssh->state;
+ const u_char *cp;
+ size_t need;
+ int r;
+
+ if (ssh->kex)
+ return SSH_ERR_INTERNAL_ERROR;
+ *typep = SSH_MSG_NONE;
+ cp = sshbuf_ptr(state->input);
+ if (state->packlen == 0) {
+ if (sshbuf_len(state->input) < 4 + 1)
+ return 0; /* packet is incomplete */
+ state->packlen = PEEK_U32(cp);
+ if (state->packlen < 4 + 1 ||
+ state->packlen > PACKET_MAX_SIZE)
+ return SSH_ERR_MESSAGE_INCOMPLETE;
+ }
+ need = state->packlen + 4;
+ if (sshbuf_len(state->input) < need)
+ return 0; /* packet is incomplete */
+ sshbuf_reset(state->incoming_packet);
+ if ((r = sshbuf_put(state->incoming_packet, cp + 4,
+ state->packlen)) != 0 ||
+ (r = sshbuf_consume(state->input, need)) != 0 ||
+ (r = sshbuf_get_u8(state->incoming_packet, NULL)) != 0 ||
+ (r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
+ return r;
+ if (ssh_packet_log_type(*typep))
+ debug3("%s: type %u", __func__, *typep);
+ /* sshbuf_dump(state->incoming_packet, stderr); */
+ /* reset for next packet */
+ state->packlen = 0;
+ return r;
+}
+
int
ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
{
@@ -1635,6 +1689,9 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
struct sshcomp *comp = NULL;
int r;
+ if (state->mux)
+ return ssh_packet_read_poll2_mux(ssh, typep, seqnr_p);
+
*typep = SSH_MSG_NONE;
if (state->packet_discard)
@@ -2875,11 +2932,43 @@ sshpkt_start(struct ssh *ssh, u_char type)
return sshbuf_put(ssh->state->outgoing_packet, buf, len);
}
+static int
+ssh_packet_send_mux(struct ssh *ssh)
+{
+ struct session_state *state = ssh->state;
+ u_char type, *cp;
+ size_t len;
+ int r;
+
+ if (ssh->kex)
+ return SSH_ERR_INTERNAL_ERROR;
+ len = sshbuf_len(state->outgoing_packet);
+ if (len < 6)
+ return SSH_ERR_INTERNAL_ERROR;
+ cp = sshbuf_mutable_ptr(state->outgoing_packet);
+ type = cp[5];
+ if (ssh_packet_log_type(type))
+ debug3("%s: type %u", __func__, type);
+ /* drop everything, but the connection protocol */
+ if (type >= SSH2_MSG_CONNECTION_MIN &&
+ type <= SSH2_MSG_CONNECTION_MAX) {
+ POKE_U32(cp, len - 4);
+ if ((r = sshbuf_putb(state->output,
+ state->outgoing_packet)) != 0)
+ return r;
+ /* sshbuf_dump(state->output, stderr); */
+ }
+ sshbuf_reset(state->outgoing_packet);
+ return 0;
+}
+
/* send it */
int
sshpkt_send(struct ssh *ssh)
{
+ if (ssh->state && ssh->state->mux)
+ return ssh_packet_send_mux(ssh);
if (compat20)
return ssh_packet_send2(ssh);
else
diff --git a/packet.h b/packet.h
index 690f2ec..0a64eb2 100644
--- a/packet.h
+++ b/packet.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.h,v 1.72 2016/09/28 16:33:07 djm Exp $ */
+/* $OpenBSD: packet.h,v 1.73 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -97,6 +97,10 @@ void ssh_packet_set_interactive(struct ssh *, int, int, int);
int ssh_packet_is_interactive(struct ssh *);
void ssh_packet_set_server(struct ssh *);
void ssh_packet_set_authenticated(struct ssh *);
+void ssh_packet_set_mux(struct ssh *);
+int ssh_packet_get_mux(struct ssh *);
+
+int ssh_packet_log_type(u_char);
int ssh_packet_send1(struct ssh *);
int ssh_packet_send2_wrapped(struct ssh *);
diff --git a/ssh.c b/ssh.c
index 5095baf..5e50fa0 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.446 2016/09/12 23:31:27 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.447 2016/09/30 09:19:13 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -213,10 +213,6 @@ static int ssh_session2(void);
static void load_public_identity_files(void);
static void main_sigchld_handler(int);
-/* from muxclient.c */
-void muxclient(const char *);
-void muxserver_listen(void);
-
/* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
static void
tilde_expand_paths(char **paths, u_int num_paths)
@@ -668,6 +664,8 @@ main(int ac, char **av)
muxclient_command = SSHMUX_COMMAND_STOP;
else if (strcmp(optarg, "cancel") == 0)
muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
+ else if (strcmp(optarg, "proxy") == 0)
+ muxclient_command = SSHMUX_COMMAND_PROXY;
else
fatal("Invalid multiplex command.");
break;
@@ -1162,7 +1160,8 @@ main(int ac, char **av)
tty_flag = options.request_tty != REQUEST_TTY_NO;
/* Force no tty */
- if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
+ if (options.request_tty == REQUEST_TTY_NO ||
+ (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY))
tty_flag = 0;
/* Do not allocate a tty if stdin is not a tty. */
if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
@@ -1239,8 +1238,16 @@ main(int ac, char **av)
if (muxclient_command != 0 && options.control_path == NULL)
fatal("No ControlPath specified for \"-O\" command");
- if (options.control_path != NULL)
- muxclient(options.control_path);
+ if (options.control_path != NULL) {
+ int sock;
+ if ((sock = muxclient(options.control_path)) >= 0) {
+ packet_set_connection(sock, sock);
+ ssh = active_state; /* XXX */
+ enable_compat20(); /* XXX */
+ packet_set_mux();
+ goto skip_connect;
+ }
+ }
/*
* If hostname canonicalisation was not enabled, then we may not
@@ -1443,6 +1450,7 @@ main(int ac, char **av)
options.certificate_files[i] = NULL;
}
+ skip_connect:
exit_status = compat20 ? ssh_session2() : ssh_session();
packet_close();
@@ -1953,7 +1961,8 @@ ssh_session2(void)
ssh_init_forwarding();
/* Start listening for multiplex clients */
- muxserver_listen();
+ if (!packet_get_mux())
+ muxserver_listen();
/*
* If we are in control persist mode and have a working mux listen
--
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