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mux.c
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/* $OpenBSD: mux.c,v 1.24 2011/01/13 21:54:53 djm Exp $ */
/*
* Copyright (c) 2002-2008 Damien Miller <[email protected]>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* ssh session multiplexing support */
/*
* TODO:
* - Better signalling from master to slave, especially passing of
* error messages
* - Better fall-back from mux slave error to new connection.
* - ExitOnForwardingFailure
* - Maybe extension mechanisms for multi-X11/multi-agent forwarding
* - Support ~^Z in mux slaves.
* - Inspect or control sessions in master.
* - If we ever support the "signal" channel request, send signals on
* sessions in master.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#ifdef HAVE_POLL_H
#include <poll.h>
#else
# ifdef HAVE_SYS_POLL_H
# include <sys/poll.h>
# endif
#endif
#ifdef HAVE_UTIL_H
# include <util.h>
#endif
#ifdef HAVE_LIBUTIL_H
# include <libutil.h>
#endif
#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "log.h"
#include "ssh.h"
#include "ssh2.h"
#include "pathnames.h"
#include "misc.h"
#include "match.h"
#include "buffer.h"
#include "channels.h"
#include "msg.h"
#include "packet.h"
#include "monitor_fdpass.h"
#include "sshpty.h"
#include "key.h"
#include "readconf.h"
#include "clientloop.h"
/* from ssh.c */
extern int tty_flag;
extern int force_tty_flag;
extern Options options;
extern int stdin_null_flag;
extern char *host;
extern int subsystem_flag;
extern Buffer command;
extern volatile sig_atomic_t quit_pending;
extern char *stdio_forward_host;
extern int stdio_forward_port;
/* Context for session open confirmation callback */
struct mux_session_confirm_ctx {
u_int want_tty;
u_int want_subsys;
u_int want_x_fwd;
u_int want_agent_fwd;
Buffer cmd;
char *term;
struct termios tio;
char **env;
u_int rid;
};
/* Context for global channel callback */
struct mux_channel_confirm_ctx {
u_int cid; /* channel id */
u_int rid; /* request id */
int fid; /* forward id */
};
/* fd to control socket */
int muxserver_sock = -1;
/* client request id */
u_int muxclient_request_id = 0;
/* Multiplexing control command */
u_int muxclient_command = 0;
/* Set when signalled. */
static volatile sig_atomic_t muxclient_terminate = 0;
/* PID of multiplex server */
static u_int muxserver_pid = 0;
static Channel *mux_listener_channel = NULL;
struct mux_master_state {
int hello_rcvd;
};
/* mux protocol messages */
#define MUX_MSG_HELLO 0x00000001
#define MUX_C_NEW_SESSION 0x10000002
#define MUX_C_ALIVE_CHECK 0x10000004
#define MUX_C_TERMINATE 0x10000005
#define MUX_C_OPEN_FWD 0x10000006
#define MUX_C_CLOSE_FWD 0x10000007
#define MUX_C_NEW_STDIO_FWD 0x10000008
#define MUX_S_OK 0x80000001
#define MUX_S_PERMISSION_DENIED 0x80000002
#define MUX_S_FAILURE 0x80000003
#define MUX_S_EXIT_MESSAGE 0x80000004
#define MUX_S_ALIVE 0x80000005
#define MUX_S_SESSION_OPENED 0x80000006
#define MUX_S_REMOTE_PORT 0x80000007
/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
#define MUX_FWD_LOCAL 1
#define MUX_FWD_REMOTE 2
#define MUX_FWD_DYNAMIC 3
static void mux_session_confirm(int, int, void *);
static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *);
static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *);
static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *);
static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *);
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 const struct {
u_int type;
int (*handler)(u_int, Channel *, Buffer *, Buffer *);
} mux_master_handlers[] = {
{ MUX_MSG_HELLO, process_mux_master_hello },
{ MUX_C_NEW_SESSION, process_mux_new_session },
{ MUX_C_ALIVE_CHECK, process_mux_alive_check },
{ MUX_C_TERMINATE, process_mux_terminate },
{ MUX_C_OPEN_FWD, process_mux_open_fwd },
{ MUX_C_CLOSE_FWD, process_mux_close_fwd },
{ MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
{ 0, NULL }
};
/* Cleanup callback fired on closure of mux slave _session_ channel */
/* ARGSUSED */
static void
mux_master_session_cleanup_cb(int cid, void *unused)
{
Channel *cc, *c = channel_by_id(cid);
debug3("%s: entering for channel %d", __func__, cid);
if (c == NULL)
fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
if (c->ctl_chan != -1) {
if ((cc = channel_by_id(c->ctl_chan)) == NULL)
fatal("%s: channel %d missing control channel %d",
__func__, c->self, c->ctl_chan);
c->ctl_chan = -1;
cc->remote_id = -1;
chan_rcvd_oclose(cc);
}
channel_cancel_cleanup(c->self);
}
/* Cleanup callback fired on closure of mux slave _control_ channel */
/* ARGSUSED */
static void
mux_master_control_cleanup_cb(int cid, void *unused)
{
Channel *sc, *c = channel_by_id(cid);
debug3("%s: entering for channel %d", __func__, cid);
if (c == NULL)
fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
if (c->remote_id != -1) {
if ((sc = channel_by_id(c->remote_id)) == NULL)
fatal("%s: channel %d missing session channel %d",
__func__, c->self, c->remote_id);
c->remote_id = -1;
sc->ctl_chan = -1;
if (sc->type != SSH_CHANNEL_OPEN) {
debug2("%s: channel %d: not open", __func__, sc->self);
chan_mark_dead(sc);
} else {
if (sc->istate == CHAN_INPUT_OPEN)
chan_read_failed(sc);
if (sc->ostate == CHAN_OUTPUT_OPEN)
chan_write_failed(sc);
}
}
channel_cancel_cleanup(c->self);
}
/* Check mux client environment variables before passing them to mux master. */
static int
env_permitted(char *env)
{
int i, ret;
char name[1024], *cp;
if ((cp = strchr(env, '=')) == NULL || cp == env)
return 0;
ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
if (ret <= 0 || (size_t)ret >= sizeof(name)) {
error("env_permitted: name '%.100s...' too long", env);
return 0;
}
for (i = 0; i < options.num_send_env; i++)
if (match_pattern(name, options.send_env[i]))
return 1;
return 0;
}
/* Mux master protocol message handlers */
static int
process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
u_int ver;
struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
if (state == NULL)
fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
if (state->hello_rcvd) {
error("%s: HELLO received twice", __func__);
return -1;
}
if (buffer_get_int_ret(&ver, m) != 0) {
malf:
error("%s: malformed message", __func__);
return -1;
}
if (ver != SSHMUX_VER) {
error("Unsupported multiplexing protocol version %d "
"(expected %d)", ver, SSHMUX_VER);
return -1;
}
debug2("%s: channel %d slave version %u", __func__, c->self, ver);
/* No extensions are presently defined */
while (buffer_len(m) > 0) {
char *name = buffer_get_string_ret(m, NULL);
char *value = buffer_get_string_ret(m, NULL);
if (name == NULL || value == NULL) {
if (name != NULL)
xfree(name);
goto malf;
}
debug2("Unrecognised slave extension \"%s\"", name);
xfree(name);
xfree(value);
}
state->hello_rcvd = 1;
return 0;
}
static int
process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
Channel *nc;
struct mux_session_confirm_ctx *cctx;
char *reserved, *cmd, *cp;
u_int i, j, len, env_len, escape_char, window, packetmax;
int new_fd[3];
/* Reply for SSHMUX_COMMAND_OPEN */
cctx = xcalloc(1, sizeof(*cctx));
cctx->term = NULL;
cctx->rid = rid;
cmd = reserved = NULL;
if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&cctx->want_tty, m) != 0 ||
buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 ||
buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 ||
buffer_get_int_ret(&cctx->want_subsys, m) != 0 ||
buffer_get_int_ret(&escape_char, m) != 0 ||
(cctx->term = buffer_get_string_ret(m, &len)) == NULL ||
(cmd = buffer_get_string_ret(m, &len)) == NULL) {
malf:
if (cmd != NULL)
xfree(cmd);
if (reserved != NULL)
xfree(reserved);
if (cctx->term != NULL)
xfree(cctx->term);
error("%s: malformed message", __func__);
return -1;
}
xfree(reserved);
reserved = NULL;
cctx->env = NULL;
env_len = 0;
while (buffer_len(m) > 0) {
#define MUX_MAX_ENV_VARS 4096
if ((cp = buffer_get_string_ret(m, &len)) == NULL) {
xfree(cmd);
goto malf;
}
if (!env_permitted(cp)) {
xfree(cp);
continue;
}
cctx->env = xrealloc(cctx->env, env_len + 2,
sizeof(*cctx->env));
cctx->env[env_len++] = cp;
cctx->env[env_len] = NULL;
if (env_len > MUX_MAX_ENV_VARS) {
error(">%d environment variables received, ignoring "
"additional", MUX_MAX_ENV_VARS);
break;
}
}
debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
"term \"%s\", cmd \"%s\", env %u", __func__, c->self,
cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
cctx->want_subsys, cctx->term, cmd, env_len);
buffer_init(&cctx->cmd);
buffer_append(&cctx->cmd, cmd, strlen(cmd));
xfree(cmd);
cmd = NULL;
/* Gather fds from client */
for(i = 0; i < 3; i++) {
if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
error("%s: failed to receive fd %d from slave",
__func__, i);
for (j = 0; j < i; j++)
close(new_fd[j]);
for (j = 0; j < env_len; j++)
xfree(cctx->env[j]);
if (env_len > 0)
xfree(cctx->env);
xfree(cctx->term);
buffer_free(&cctx->cmd);
xfree(cctx);
/* prepare reply */
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r,
"did not receive file descriptors");
return -1;
}
}
debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
new_fd[0], new_fd[1], new_fd[2]);
/* XXX support multiple child sessions in future */
if (c->remote_id != -1) {
debug2("%s: session already open", __func__);
/* prepare reply */
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Multiple sessions not supported");
cleanup:
close(new_fd[0]);
close(new_fd[1]);
close(new_fd[2]);
xfree(cctx->term);
if (env_len != 0) {
for (i = 0; i < env_len; i++)
xfree(cctx->env[i]);
xfree(cctx->env);
}
buffer_free(&cctx->cmd);
return 0;
}
if (options.control_master == SSHCTL_MASTER_ASK ||
options.control_master == SSHCTL_MASTER_AUTO_ASK) {
if (!ask_permission("Allow shared connection to %s? ", host)) {
debug2("%s: session refused by user", __func__);
/* prepare reply */
buffer_put_int(r, MUX_S_PERMISSION_DENIED);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Permission denied");
goto cleanup;
}
}
/* Try to pick up ttymodes from client before it goes raw */
if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
error("%s: tcgetattr: %s", __func__, strerror(errno));
/* enable nonblocking unless tty */
if (!isatty(new_fd[0]))
set_nonblock(new_fd[0]);
if (!isatty(new_fd[1]))
set_nonblock(new_fd[1]);
if (!isatty(new_fd[2]))
set_nonblock(new_fd[2]);
window = CHAN_SES_WINDOW_DEFAULT;
packetmax = CHAN_SES_PACKET_DEFAULT;
if (cctx->want_tty) {
window >>= 1;
packetmax >>= 1;
}
nc = channel_new("session", SSH_CHANNEL_OPENING,
new_fd[0], new_fd[1], new_fd[2], window, packetmax,
CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
nc->ctl_chan = c->self; /* link session -> control channel */
c->remote_id = nc->self; /* link control -> session channel */
if (cctx->want_tty && escape_char != 0xffffffff) {
channel_register_filter(nc->self,
client_simple_escape_filter, NULL,
client_filter_cleanup,
client_new_escape_filter_ctx((int)escape_char));
}
debug2("%s: channel_new: %d linked to control channel %d",
__func__, nc->self, nc->ctl_chan);
channel_send_open(nc->self);
channel_register_open_confirm(nc->self, mux_session_confirm, cctx);
c->mux_pause = 1; /* stop handling messages until open_confirm done */
channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
/* reply is deferred, sent by mux_session_confirm */
return 0;
}
static int
process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
debug2("%s: channel %d: alive check", __func__, c->self);
/* prepare reply */
buffer_put_int(r, MUX_S_ALIVE);
buffer_put_int(r, rid);
buffer_put_int(r, (u_int)getpid());
return 0;
}
static int
process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
debug2("%s: channel %d: terminate request", __func__, c->self);
if (options.control_master == SSHCTL_MASTER_ASK ||
options.control_master == SSHCTL_MASTER_AUTO_ASK) {
if (!ask_permission("Terminate shared connection to %s? ",
host)) {
debug2("%s: termination refused by user", __func__);
buffer_put_int(r, MUX_S_PERMISSION_DENIED);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Permission denied");
return 0;
}
}
quit_pending = 1;
buffer_put_int(r, MUX_S_OK);
buffer_put_int(r, rid);
/* XXX exit happens too soon - message never makes it to client */
return 0;
}
static char *
format_forward(u_int ftype, Forward *fwd)
{
char *ret;
switch (ftype) {
case MUX_FWD_LOCAL:
xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
(fwd->listen_host == NULL) ?
(options.gateway_ports ? "*" : "LOCALHOST") :
fwd->listen_host, fwd->listen_port,
fwd->connect_host, fwd->connect_port);
break;
case MUX_FWD_DYNAMIC:
xasprintf(&ret, "dynamic forward %.200s:%d -> *",
(fwd->listen_host == NULL) ?
(options.gateway_ports ? "*" : "LOCALHOST") :
fwd->listen_host, fwd->listen_port);
break;
case MUX_FWD_REMOTE:
xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
(fwd->listen_host == NULL) ?
"LOCALHOST" : fwd->listen_host,
fwd->listen_port,
fwd->connect_host, fwd->connect_port);
break;
default:
fatal("%s: unknown forward type %u", __func__, ftype);
}
return ret;
}
static int
compare_host(const char *a, const char *b)
{
if (a == NULL && b == NULL)
return 1;
if (a == NULL || b == NULL)
return 0;
return strcmp(a, b) == 0;
}
static int
compare_forward(Forward *a, Forward *b)
{
if (!compare_host(a->listen_host, b->listen_host))
return 0;
if (a->listen_port != b->listen_port)
return 0;
if (!compare_host(a->connect_host, b->connect_host))
return 0;
if (a->connect_port != b->connect_port)
return 0;
return 1;
}
static void
mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
{
struct mux_channel_confirm_ctx *fctx = ctxt;
char *failmsg = NULL;
Forward *rfwd;
Channel *c;
Buffer out;
if ((c = channel_by_id(fctx->cid)) == NULL) {
/* no channel for reply */
error("%s: unknown channel", __func__);
return;
}
buffer_init(&out);
if (fctx->fid >= options.num_remote_forwards) {
xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
goto fail;
}
rfwd = &options.remote_forwards[fctx->fid];
debug("%s: %s for: listen %d, connect %s:%d", __func__,
type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
if (type == SSH2_MSG_REQUEST_SUCCESS) {
if (rfwd->listen_port == 0) {
rfwd->allocated_port = packet_get_int();
logit("Allocated port %u for mux remote forward"
" to %s:%d", rfwd->allocated_port,
rfwd->connect_host, rfwd->connect_port);
buffer_put_int(&out, MUX_S_REMOTE_PORT);
buffer_put_int(&out, fctx->rid);
buffer_put_int(&out, rfwd->allocated_port);
} else {
buffer_put_int(&out, MUX_S_OK);
buffer_put_int(&out, fctx->rid);
}
goto out;
} else {
xasprintf(&failmsg, "remote port forwarding failed for "
"listen port %d", rfwd->listen_port);
}
fail:
error("%s: %s", __func__, failmsg);
buffer_put_int(&out, MUX_S_FAILURE);
buffer_put_int(&out, fctx->rid);
buffer_put_cstring(&out, failmsg);
xfree(failmsg);
out:
buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out));
buffer_free(&out);
if (c->mux_pause <= 0)
fatal("%s: mux_pause %d", __func__, c->mux_pause);
c->mux_pause = 0; /* start processing messages again */
}
static int
process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
Forward fwd;
char *fwd_desc = NULL;
u_int ftype;
int i, ret = 0, freefwd = 1;
fwd.listen_host = fwd.connect_host = NULL;
if (buffer_get_int_ret(&ftype, m) != 0 ||
(fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&fwd.listen_port, m) != 0 ||
(fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&fwd.connect_port, m) != 0) {
error("%s: malformed message", __func__);
ret = -1;
goto out;
}
if (*fwd.listen_host == '\0') {
xfree(fwd.listen_host);
fwd.listen_host = NULL;
}
if (*fwd.connect_host == '\0') {
xfree(fwd.connect_host);
fwd.connect_host = NULL;
}
debug2("%s: channel %d: request %s", __func__, c->self,
(fwd_desc = format_forward(ftype, &fwd)));
if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
ftype != MUX_FWD_DYNAMIC) {
logit("%s: invalid forwarding type %u", __func__, ftype);
invalid:
if (fwd.listen_host)
xfree(fwd.listen_host);
if (fwd.connect_host)
xfree(fwd.connect_host);
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Invalid forwarding request");
return 0;
}
if (fwd.listen_port >= 65536) {
logit("%s: invalid listen port %u", __func__,
fwd.listen_port);
goto invalid;
}
if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC &&
ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) {
logit("%s: invalid connect port %u", __func__,
fwd.connect_port);
goto invalid;
}
if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) {
logit("%s: missing connect host", __func__);
goto invalid;
}
/* Skip forwards that have already been requested */
switch (ftype) {
case MUX_FWD_LOCAL:
case MUX_FWD_DYNAMIC:
for (i = 0; i < options.num_local_forwards; i++) {
if (compare_forward(&fwd,
options.local_forwards + i)) {
exists:
debug2("%s: found existing forwarding",
__func__);
buffer_put_int(r, MUX_S_OK);
buffer_put_int(r, rid);
goto out;
}
}
break;
case MUX_FWD_REMOTE:
for (i = 0; i < options.num_remote_forwards; i++) {
if (compare_forward(&fwd,
options.remote_forwards + i)) {
if (fwd.listen_port != 0)
goto exists;
debug2("%s: found allocated port",
__func__);
buffer_put_int(r, MUX_S_REMOTE_PORT);
buffer_put_int(r, rid);
buffer_put_int(r,
options.remote_forwards[i].allocated_port);
goto out;
}
}
break;
}
if (options.control_master == SSHCTL_MASTER_ASK ||
options.control_master == SSHCTL_MASTER_AUTO_ASK) {
if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
debug2("%s: forwarding refused by user", __func__);
buffer_put_int(r, MUX_S_PERMISSION_DENIED);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Permission denied");
goto out;
}
}
if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
if (channel_setup_local_fwd_listener(fwd.listen_host,
fwd.listen_port, fwd.connect_host, fwd.connect_port,
options.gateway_ports) < 0) {
fail:
logit("slave-requested %s failed", fwd_desc);
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Port forwarding failed");
goto out;
}
add_local_forward(&options, &fwd);
freefwd = 0;
} else {
struct mux_channel_confirm_ctx *fctx;
if (channel_request_remote_forwarding(fwd.listen_host,
fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0)
goto fail;
add_remote_forward(&options, &fwd);
fctx = xcalloc(1, sizeof(*fctx));
fctx->cid = c->self;
fctx->rid = rid;
fctx->fid = options.num_remote_forwards - 1;
client_register_global_confirm(mux_confirm_remote_forward,
fctx);
freefwd = 0;
c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
/* delayed reply in mux_confirm_remote_forward */
goto out;
}
buffer_put_int(r, MUX_S_OK);
buffer_put_int(r, rid);
out:
if (fwd_desc != NULL)
xfree(fwd_desc);
if (freefwd) {
if (fwd.listen_host != NULL)
xfree(fwd.listen_host);
if (fwd.connect_host != NULL)
xfree(fwd.connect_host);
}
return ret;
}
static int
process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
Forward fwd;
char *fwd_desc = NULL;
u_int ftype;
int ret = 0;
fwd.listen_host = fwd.connect_host = NULL;
if (buffer_get_int_ret(&ftype, m) != 0 ||
(fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&fwd.listen_port, m) != 0 ||
(fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&fwd.connect_port, m) != 0) {
error("%s: malformed message", __func__);
ret = -1;
goto out;
}
if (*fwd.listen_host == '\0') {
xfree(fwd.listen_host);
fwd.listen_host = NULL;
}
if (*fwd.connect_host == '\0') {
xfree(fwd.connect_host);
fwd.connect_host = NULL;
}
debug2("%s: channel %d: request %s", __func__, c->self,
(fwd_desc = format_forward(ftype, &fwd)));
/* XXX implement this */
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r, "unimplemented");
out:
if (fwd_desc != NULL)
xfree(fwd_desc);
if (fwd.listen_host != NULL)
xfree(fwd.listen_host);
if (fwd.connect_host != NULL)
xfree(fwd.connect_host);
return ret;
}
static int
process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
Channel *nc;
char *reserved, *chost;
u_int cport, i, j;
int new_fd[2];
chost = reserved = NULL;
if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
(chost = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&cport, m) != 0) {
if (reserved != NULL)
xfree(reserved);
if (chost != NULL)
xfree(chost);
error("%s: malformed message", __func__);
return -1;
}
xfree(reserved);
debug2("%s: channel %d: request stdio fwd to %s:%u",
__func__, c->self, chost, cport);
/* Gather fds from client */
for(i = 0; i < 2; i++) {
if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
error("%s: failed to receive fd %d from slave",
__func__, i);
for (j = 0; j < i; j++)
close(new_fd[j]);
xfree(chost);
/* prepare reply */
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r,
"did not receive file descriptors");
return -1;
}
}
debug3("%s: got fds stdin %d, stdout %d", __func__,
new_fd[0], new_fd[1]);
/* XXX support multiple child sessions in future */
if (c->remote_id != -1) {
debug2("%s: session already open", __func__);
/* prepare reply */
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Multiple sessions not supported");
cleanup:
close(new_fd[0]);
close(new_fd[1]);
xfree(chost);
return 0;
}
if (options.control_master == SSHCTL_MASTER_ASK ||
options.control_master == SSHCTL_MASTER_AUTO_ASK) {
if (!ask_permission("Allow forward to %s:%u? ",
chost, cport)) {
debug2("%s: stdio fwd refused by user", __func__);
/* prepare reply */
buffer_put_int(r, MUX_S_PERMISSION_DENIED);
buffer_put_int(r, rid);
buffer_put_cstring(r, "Permission denied");
goto cleanup;
}
}
/* enable nonblocking unless tty */
if (!isatty(new_fd[0]))
set_nonblock(new_fd[0]);
if (!isatty(new_fd[1]))
set_nonblock(new_fd[1]);
nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]);
nc->ctl_chan = c->self; /* link session -> control channel */
c->remote_id = nc->self; /* link control -> session channel */
debug2("%s: channel_new: %d linked to control channel %d",
__func__, nc->self, nc->ctl_chan);
channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
/* prepare reply */
/* XXX defer until channel confirmed */
buffer_put_int(r, MUX_S_SESSION_OPENED);
buffer_put_int(r, rid);
buffer_put_int(r, nc->self);
return 0;
}
/* Channel callbacks fired on read/write from mux slave fd */
static int
mux_master_read_cb(Channel *c)
{
struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
Buffer in, out;
void *ptr;
u_int type, rid, have, i;
int ret = -1;
/* Setup ctx and */
if (c->mux_ctx == NULL) {
state = xcalloc(1, sizeof(*state));
c->mux_ctx = state;
channel_register_cleanup(c->self,
mux_master_control_cleanup_cb, 0);
/* Send hello */
buffer_init(&out);
buffer_put_int(&out, MUX_MSG_HELLO);
buffer_put_int(&out, SSHMUX_VER);
/* no extensions */
buffer_put_string(&c->output, buffer_ptr(&out),
buffer_len(&out));
buffer_free(&out);
debug3("%s: channel %d: hello sent", __func__, c->self);
return 0;
}
buffer_init(&in);
buffer_init(&out);
/* Channel code ensures that we receive whole packets */
if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) {
malf:
error("%s: malformed message", __func__);
goto out;
}
buffer_append(&in, ptr, have);
if (buffer_get_int_ret(&type, &in) != 0)
goto malf;
debug3("%s: channel %d packet type 0x%08x len %u",
__func__, c->self, type, buffer_len(&in));
if (type == MUX_MSG_HELLO)
rid = 0;
else {
if (!state->hello_rcvd) {
error("%s: expected MUX_MSG_HELLO(0x%08x), "
"received 0x%08x", __func__, MUX_MSG_HELLO, type);
goto out;
}
if (buffer_get_int_ret(&rid, &in) != 0)
goto malf;
}
for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
if (type == mux_master_handlers[i].type) {
ret = mux_master_handlers[i].handler(rid, c, &in, &out);
break;
}
}
if (mux_master_handlers[i].handler == NULL) {
error("%s: unsupported mux message 0x%08x", __func__, type);
buffer_put_int(&out, MUX_S_FAILURE);
buffer_put_int(&out, rid);
buffer_put_cstring(&out, "unsupported request");
ret = 0;
}
/* Enqueue reply packet */
if (buffer_len(&out) != 0) {
buffer_put_string(&c->output, buffer_ptr(&out),
buffer_len(&out));
}
out:
buffer_free(&in);
buffer_free(&out);
return ret;
}
void
mux_exit_message(Channel *c, int exitval)