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openssh-portable/mux.c

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/* $OpenBSD: mux.c,v 1.45 2014/04/28 03:09:18 djm Exp $ */
/*
* Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
*
* 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
#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 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_C_STOP_LISTENING 0x10000009
#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
#define MUX_S_TTY_ALLOC_FAIL 0x80000008
/* 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 int process_mux_stop_listening(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 },
{ MUX_C_STOP_LISTENING, process_mux_stop_listening },
{ 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 &&
sc->type != SSH_CHANNEL_OPENING) {
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) {
free(name);
free(value);
goto malf;
}
debug2("Unrecognised slave extension \"%s\"", name);
free(name);
free(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;
cctx->env = NULL;
env_len = 0;
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:
free(cmd);
free(reserved);
for (j = 0; j < env_len; j++)
free(cctx->env[j]);
free(cctx->env);
free(cctx->term);
free(cctx);
error("%s: malformed message", __func__);
return -1;
}
free(reserved);
reserved = NULL;
while (buffer_len(m) > 0) {
#define MUX_MAX_ENV_VARS 4096
if ((cp = buffer_get_string_ret(m, &len)) == NULL)
goto malf;
if (!env_permitted(cp)) {
free(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));
free(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++)
free(cctx->env[j]);
free(cctx->env);
free(cctx->term);
buffer_free(&cctx->cmd);
free(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]);
free(cctx->term);
if (env_len != 0) {
for (i = 0; i < env_len; i++)
free(cctx->env[i]);
free(cctx->env);
}
buffer_free(&cctx->cmd);
free(cctx);
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);
channel_update_permitted_opens(rfwd->handle,
rfwd->allocated_port);
} else {
buffer_put_int(&out, MUX_S_OK);
buffer_put_int(&out, fctx->rid);
}
goto out;
} else {
if (rfwd->listen_port == 0)
channel_update_permitted_opens(rfwd->handle, -1);
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);
free(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;
u_int lport, cport;
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(&lport, m) != 0 ||
(fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&cport, m) != 0 ||
lport > 65535 || cport > 65535) {
error("%s: malformed message", __func__);
ret = -1;
goto out;
}
fwd.listen_port = lport;
fwd.connect_port = cport;
if (*fwd.listen_host == '\0') {
free(fwd.listen_host);
fwd.listen_host = NULL;
}
if (*fwd.connect_host == '\0') {
free(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:
free(fwd.listen_host);
free(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)) {
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;
fwd.handle = channel_request_remote_forwarding(fwd.listen_host,
fwd.listen_port, fwd.connect_host, fwd.connect_port);
if (fwd.handle < 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:
free(fwd_desc);
if (freefwd) {
free(fwd.listen_host);
free(fwd.connect_host);
}
return ret;
}
static int
process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
Forward fwd, *found_fwd;
char *fwd_desc = NULL;
const char *error_reason = NULL;
u_int ftype;
int i, listen_port, ret = 0;
u_int lport, cport;
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(&lport, m) != 0 ||
(fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
buffer_get_int_ret(&cport, m) != 0 ||
lport > 65535 || cport > 65535) {
error("%s: malformed message", __func__);
ret = -1;
goto out;
}
fwd.listen_port = lport;
fwd.connect_port = cport;
if (*fwd.listen_host == '\0') {
free(fwd.listen_host);
fwd.listen_host = NULL;
}
if (*fwd.connect_host == '\0') {
free(fwd.connect_host);
fwd.connect_host = NULL;
}
debug2("%s: channel %d: request cancel %s", __func__, c->self,
(fwd_desc = format_forward(ftype, &fwd)));
/* make sure this has been requested */
found_fwd = NULL;
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)) {
found_fwd = options.local_forwards + i;
break;
}
}
break;
case MUX_FWD_REMOTE:
for (i = 0; i < options.num_remote_forwards; i++) {
if (compare_forward(&fwd,
options.remote_forwards + i)) {
found_fwd = options.remote_forwards + i;
break;
}
}
break;
}
if (found_fwd == NULL)
error_reason = "port not forwarded";
else if (ftype == MUX_FWD_REMOTE) {
/*
* This shouldn't fail unless we confused the host/port
* between options.remote_forwards and permitted_opens.
* However, for dynamic allocated listen ports we need
* to lookup the actual listen port.
*/
listen_port = (fwd.listen_port == 0) ?
found_fwd->allocated_port : fwd.listen_port;
if (channel_request_rforward_cancel(fwd.listen_host,
listen_port) == -1)
error_reason = "port not in permitted opens";
} else { /* local and dynamic forwards */
/* Ditto */
if (channel_cancel_lport_listener(fwd.listen_host,
fwd.listen_port, fwd.connect_port,
options.gateway_ports) == -1)
error_reason = "port not found";
}
if (error_reason == NULL) {
buffer_put_int(r, MUX_S_OK);
buffer_put_int(r, rid);
free(found_fwd->listen_host);
free(found_fwd->connect_host);
found_fwd->listen_host = found_fwd->connect_host = NULL;
found_fwd->listen_port = found_fwd->connect_port = 0;
} else {
buffer_put_int(r, MUX_S_FAILURE);
buffer_put_int(r, rid);
buffer_put_cstring(r, error_reason);
}
out:
free(fwd_desc);
free(fwd.listen_host);
free(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) {
free(reserved);
free(chost);
error("%s: malformed message", __func__);
return -1;
}
free(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]);
free(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]);
free(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;
}
static int
process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
{
debug("%s: channel %d: stop listening", __func__, c->self);
if (options.control_master == SSHCTL_MASTER_ASK ||
options.control_master == SSHCTL_MASTER_AUTO_ASK) {
if (!ask_permission("Disable further multiplexing on shared "
"connection to %s? ", host)) {
debug2("%s: stop listen 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;
}
}
if (mux_listener_channel != NULL) {
channel_free(mux_listener_channel);
client_stop_mux();
free(options.control_path);
options.control_path = NULL;
mux_listener_channel = NULL;
muxserver_sock = -1;
}
/* prepare reply */
buffer_put_int(r, MUX_S_OK);
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)
{
struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
Buffer in, out;
const u_char *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)
{
Buffer m;
Channel *mux_chan;
debug3("%s: channel %d: exit message, exitval %d", __func__, c->self,
exitval);
if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
fatal("%s: channel %d missing mux channel %d",
__func__, c->self, c->ctl_chan);
/* Append exit message packet to control socket output queue */
buffer_init(&m);
buffer_put_int(&m, MUX_S_EXIT_MESSAGE);
buffer_put_int(&m, c->self);
buffer_put_int(&m, exitval);
buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
buffer_free(&m);
}
void
mux_tty_alloc_failed(Channel *c)
{
Buffer m;
Channel *mux_chan;
debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
fatal("%s: channel %d missing mux channel %d",
__func__, c->self, c->ctl_chan);
/* Append exit message packet to control socket output queue */
buffer_init(&m);
buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL);
buffer_put_int(&m, c->self);
buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
buffer_free(&m);
}
/* Prepare a mux master to listen on a Unix domain socket. */
void
muxserver_listen(void)
{
struct sockaddr_un addr;
socklen_t sun_len;
mode_t old_umask;
char *orig_control_path = options.control_path;
char rbuf[16+1];
u_int i, r;
if (options.control_path == NULL ||
options.control_master == SSHCTL_MASTER_NO)
return;
debug("setting up multiplex master socket");
/*
* Use a temporary path before listen so we can pseudo-atomically
* establish the listening socket in its final location to avoid
* other processes racing in between bind() and listen() and hitting
* an unready socket.
*/
for (i = 0; i < sizeof(rbuf) - 1; i++) {
r = arc4random_uniform(26+26+10);
rbuf[i] = (r < 26) ? 'a' + r :
(r < 26*2) ? 'A' + r - 26 :
'0' + r - 26 - 26;
}
rbuf[sizeof(rbuf) - 1] = '\0';
options.control_path = NULL;
xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
debug3("%s: temporary control path %s", __func__, options.control_path);
memset(&addr, '\0', sizeof(addr));
addr.sun_family = AF_UNIX;
sun_len = offsetof(struct sockaddr_un, sun_path) +
strlen(options.control_path) + 1;
if (strlcpy(addr.sun_path, options.control_path,
sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) {
error("ControlPath \"%s\" too long for Unix domain socket",
options.control_path);
goto disable_mux_master;
}
if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
fatal("%s socket(): %s", __func__, strerror(errno));
old_umask = umask(0177);
if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) {
if (errno == EINVAL || errno == EADDRINUSE) {
error("ControlSocket %s already exists, "
"disabling multiplexing", options.control_path);
disable_mux_master:
if (muxserver_sock != -1) {
close(muxserver_sock);
muxserver_sock = -1;
}
free(orig_control_path);
free(options.control_path);
options.control_path = NULL;
options.control_master = SSHCTL_MASTER_NO;
return;
} else
fatal("%s bind(): %s", __func__, strerror(errno));
}
umask(old_umask);
if (listen(muxserver_sock, 64) == -1)
fatal("%s listen(): %s", __func__, strerror(errno));
/* Now atomically "move" the mux socket into position */
if (link(options.control_path, orig_control_path) != 0) {
if (errno != EEXIST) {
fatal("%s: link mux listener %s => %s: %s", __func__,
options.control_path, orig_control_path,
strerror(errno));
}
error("ControlSocket %s already exists, disabling multiplexing",
orig_control_path);
unlink(options.control_path);
goto disable_mux_master;
}
unlink(options.control_path);
free(options.control_path);
options.control_path = orig_control_path;
set_nonblock(muxserver_sock);
mux_listener_channel = channel_new("mux listener",
SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
0, options.control_path, 1);
mux_listener_channel->mux_rcb = mux_master_read_cb;
debug3("%s: mux listener channel %d fd %d", __func__,
mux_listener_channel->self, mux_listener_channel->sock);
}
/* Callback on open confirmation in mux master for a mux client session. */
static void
mux_session_confirm(int id, int success, void *arg)
{
struct mux_session_confirm_ctx *cctx = arg;
const char *display;
Channel *c, *cc;
int i;
Buffer reply;
if (cctx == NULL)
fatal("%s: cctx == NULL", __func__);
if ((c = channel_by_id(id)) == NULL)
fatal("%s: no channel for id %d", __func__, id);
if ((cc = channel_by_id(c->ctl_chan)) == NULL)
fatal("%s: channel %d lacks control channel %d", __func__,
id, c->ctl_chan);
if (!success) {
debug3("%s: sending failure reply", __func__);
/* prepare reply */
buffer_init(&reply);
buffer_put_int(&reply, MUX_S_FAILURE);
buffer_put_int(&reply, cctx->rid);
buffer_put_cstring(&reply, "Session open refused by peer");
goto done;
}
display = getenv("DISPLAY");
if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
char *proto, *data;
/* Get reasonable local authentication information. */
client_x11_get_proto(display, options.xauth_location,
options.forward_x11_trusted, options.forward_x11_timeout,
&proto, &data);
/* Request forwarding with authentication spoofing. */
debug("Requesting X11 forwarding with authentication "
"spoofing.");
x11_request_forwarding_with_spoofing(id, display, proto,
data, 1);
client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
/* XXX exit_on_forward_failure */
}
if (cctx->want_agent_fwd && options.forward_agent) {
debug("Requesting authentication agent forwarding.");
channel_request_start(id, "auth-agent-req@openssh.com", 0);
packet_send();
}
client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
debug3("%s: sending success reply", __func__);
/* prepare reply */
buffer_init(&reply);
buffer_put_int(&reply, MUX_S_SESSION_OPENED);
buffer_put_int(&reply, cctx->rid);
buffer_put_int(&reply, c->self);
done:
/* Send reply */
buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
buffer_free(&reply);
if (cc->mux_pause <= 0)
fatal("%s: mux_pause %d", __func__, cc->mux_pause);
cc->mux_pause = 0; /* start processing messages again */
c->open_confirm_ctx = NULL;
buffer_free(&cctx->cmd);
free(cctx->term);
if (cctx->env != NULL) {
for (i = 0; cctx->env[i] != NULL; i++)
free(cctx->env[i]);
free(cctx->env);
}
free(cctx);
}
/* ** Multiplexing client support */
/* Exit signal handler */
static void
control_client_sighandler(int signo)
{
muxclient_terminate = signo;
}
/*
* Relay signal handler - used to pass some signals from mux client to
* mux master.
*/
static void
control_client_sigrelay(int signo)
{
int save_errno = errno;
if (muxserver_pid > 1)
kill(muxserver_pid, signo);
errno = save_errno;
}
static int
mux_client_read(int fd, Buffer *b, u_int need)
{
u_int have;
ssize_t len;
u_char *p;
struct pollfd pfd;
pfd.fd = fd;
pfd.events = POLLIN;
p = buffer_append_space(b, need);
for (have = 0; have < need; ) {
if (muxclient_terminate) {
errno = EINTR;
return -1;
}
len = read(fd, p + have, need - have);
if (len < 0) {
switch (errno) {
#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
case EWOULDBLOCK:
#endif
case EAGAIN:
(void)poll(&pfd, 1, -1);
/* FALLTHROUGH */
case EINTR:
continue;
default:
return -1;
}
}
if (len == 0) {
errno = EPIPE;
return -1;
}
have += (u_int)len;
}
return 0;
}
static int
mux_client_write_packet(int fd, Buffer *m)
{
Buffer queue;
u_int have, need;
int oerrno, len;
u_char *ptr;
struct pollfd pfd;
pfd.fd = fd;
pfd.events = POLLOUT;
buffer_init(&queue);
buffer_put_string(&queue, buffer_ptr(m), buffer_len(m));
need = buffer_len(&queue);
ptr = buffer_ptr(&queue);
for (have = 0; have < need; ) {
if (muxclient_terminate) {
buffer_free(&queue);
errno = EINTR;
return -1;
}
len = write(fd, ptr + have, need - have);
if (len < 0) {
switch (errno) {
#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
case EWOULDBLOCK:
#endif
case EAGAIN:
(void)poll(&pfd, 1, -1);
/* FALLTHROUGH */
case EINTR:
continue;
default:
oerrno = errno;
buffer_free(&queue);
errno = oerrno;
return -1;
}
}
if (len == 0) {
buffer_free(&queue);
errno = EPIPE;
return -1;
}
have += (u_int)len;
}
buffer_free(&queue);
return 0;
}
static int
mux_client_read_packet(int fd, Buffer *m)
{
Buffer queue;
u_int need, have;
const u_char *ptr;
int oerrno;
buffer_init(&queue);
if (mux_client_read(fd, &queue, 4) != 0) {
if ((oerrno = errno) == EPIPE)
debug3("%s: read header failed: %s", __func__,
strerror(errno));
buffer_free(&queue);
errno = oerrno;
return -1;
}
need = get_u32(buffer_ptr(&queue));
if (mux_client_read(fd, &queue, need) != 0) {
oerrno = errno;
debug3("%s: read body failed: %s", __func__, strerror(errno));
buffer_free(&queue);
errno = oerrno;
return -1;
}
ptr = buffer_get_string_ptr(&queue, &have);
buffer_append(m, ptr, have);
buffer_free(&queue);
return 0;
}
static int
mux_client_hello_exchange(int fd)
{
Buffer m;
u_int type, ver;
buffer_init(&m);
buffer_put_int(&m, MUX_MSG_HELLO);
buffer_put_int(&m, SSHMUX_VER);
/* no extensions */
if (mux_client_write_packet(fd, &m) != 0)
fatal("%s: write packet: %s", __func__, strerror(errno));
buffer_clear(&m);
/* Read their HELLO */
if (mux_client_read_packet(fd, &m) != 0) {
buffer_free(&m);
return -1;
}
type = buffer_get_int(&m);
if (type != MUX_MSG_HELLO)
fatal("%s: expected HELLO (%u) received %u",
__func__, MUX_MSG_HELLO, type);
ver = buffer_get_int(&m);
if (ver != SSHMUX_VER)
fatal("Unsupported multiplexing protocol version %d "
"(expected %d)", ver, SSHMUX_VER);
debug2("%s: master version %u", __func__, ver);
/* No extensions are presently defined */
while (buffer_len(&m) > 0) {
char *name = buffer_get_string(&m, NULL);
char *value = buffer_get_string(&m, NULL);
debug2("Unrecognised master extension \"%s\"", name);
free(name);
free(value);
}
buffer_free(&m);
return 0;
}
static u_int
mux_client_request_alive(int fd)
{
Buffer m;
char *e;
u_int pid, type, rid;
debug3("%s: entering", __func__);
buffer_init(&m);
buffer_put_int(&m, MUX_C_ALIVE_CHECK);
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_ALIVE) {
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);
pid = buffer_get_int(&m);
buffer_free(&m);
debug3("%s: done pid = %u", __func__, pid);
muxclient_request_id++;
return pid;
}
static void
mux_client_request_terminate(int fd)
{
Buffer m;
char *e;
u_int type, rid;
debug3("%s: entering", __func__);
buffer_init(&m);
buffer_put_int(&m, MUX_C_TERMINATE);
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) {
/* Remote end exited already */
if (errno == EPIPE) {
buffer_free(&m);
return;
}
fatal("%s: read from master failed: %s",
__func__, strerror(errno));
}
type = buffer_get_int(&m);
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);
switch (type) {
case MUX_S_OK:
break;
case MUX_S_PERMISSION_DENIED:
e = buffer_get_string(&m, NULL);
fatal("Master refused termination request: %s", e);
case MUX_S_FAILURE:
e = buffer_get_string(&m, NULL);
fatal("%s: termination request failed: %s", __func__, e);
default:
fatal("%s: unexpected response from master 0x%08x",
__func__, type);
}
buffer_free(&m);
muxclient_request_id++;
}
static int
mux_client_forward(int fd, int cancel_flag, u_int ftype, Forward *fwd)
{
Buffer m;
char *e, *fwd_desc;
u_int type, rid;
fwd_desc = format_forward(ftype, fwd);
debug("Requesting %s %s",
cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
free(fwd_desc);
buffer_init(&m);
buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD);
buffer_put_int(&m, muxclient_request_id);
buffer_put_int(&m, ftype);
buffer_put_cstring(&m,
fwd->listen_host == NULL ? "" : fwd->listen_host);
buffer_put_int(&m, fwd->listen_port);
buffer_put_cstring(&m,
fwd->connect_host == NULL ? "" : fwd->connect_host);
buffer_put_int(&m, fwd->connect_port);
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 -1;
}
type = buffer_get_int(&m);
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);
switch (type) {
case MUX_S_OK:
break;
case MUX_S_REMOTE_PORT:
if (cancel_flag)
fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__);
fwd->allocated_port = buffer_get_int(&m);
logit("Allocated port %u for remote forward to %s:%d",
fwd->allocated_port,
fwd->connect_host ? fwd->connect_host : "",
fwd->connect_port);
if (muxclient_command == SSHMUX_COMMAND_FORWARD)
fprintf(stdout, "%u\n", fwd->allocated_port);
break;
case MUX_S_PERMISSION_DENIED:
e = buffer_get_string(&m, NULL);
buffer_free(&m);
error("Master refused forwarding request: %s", e);
return -1;
case MUX_S_FAILURE:
e = buffer_get_string(&m, NULL);
buffer_free(&m);
error("%s: forwarding request failed: %s", __func__, e);
return -1;
default:
fatal("%s: unexpected response from master 0x%08x",
__func__, type);
}
buffer_free(&m);
muxclient_request_id++;
return 0;
}
static int
mux_client_forwards(int fd, int cancel_flag)
{
int i, ret = 0;
debug3("%s: %s forwardings: %d local, %d remote", __func__,
cancel_flag ? "cancel" : "request",
options.num_local_forwards, options.num_remote_forwards);
/* XXX ExitOnForwardingFailure */
for (i = 0; i < options.num_local_forwards; i++) {
if (mux_client_forward(fd, cancel_flag,
options.local_forwards[i].connect_port == 0 ?
MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
options.local_forwards + i) != 0)
ret = -1;
}
for (i = 0; i < options.num_remote_forwards; i++) {
if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
options.remote_forwards + i) != 0)
ret = -1;
}
return ret;
}
static int
mux_client_request_session(int fd)
{
Buffer m;
char *e, *term;
u_int i, rid, sid, esid, exitval, type, exitval_seen;
extern char **environ;
int devnull, rawmode;
debug3("%s: entering", __func__);
if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
error("%s: master alive request failed", __func__);
return -1;
}
signal(SIGPIPE, SIG_IGN);
if (stdin_null_flag) {
if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
fatal("open(/dev/null): %s", strerror(errno));
if (dup2(devnull, STDIN_FILENO) == -1)
fatal("dup2: %s", strerror(errno));
if (devnull > STDERR_FILENO)
close(devnull);
}
term = getenv("TERM");
buffer_init(&m);
buffer_put_int(&m, MUX_C_NEW_SESSION);
buffer_put_int(&m, muxclient_request_id);
buffer_put_cstring(&m, ""); /* reserved */
buffer_put_int(&m, tty_flag);
buffer_put_int(&m, options.forward_x11);
buffer_put_int(&m, options.forward_agent);
buffer_put_int(&m, subsystem_flag);
buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ?
0xffffffff : (u_int)options.escape_char);
buffer_put_cstring(&m, term == NULL ? "" : term);
buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command));
if (options.num_send_env > 0 && environ != NULL) {
/* Pass environment */
for (i = 0; environ[i] != NULL; i++) {
if (env_permitted(environ[i])) {
buffer_put_cstring(&m, environ[i]);
}
}
}
if (mux_client_write_packet(fd, &m) != 0)
fatal("%s: write packet: %s", __func__, strerror(errno));
/* Send the stdio file descriptors */
if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
mm_send_fd(fd, STDOUT_FILENO) == -1 ||
mm_send_fd(fd, STDERR_FILENO) == -1)
fatal("%s: send fds failed", __func__);
debug3("%s: session request sent", __func__);
/* Read their reply */
buffer_clear(&m);
if (mux_client_read_packet(fd, &m) != 0) {
error("%s: read from master failed: %s",
__func__, strerror(errno));
buffer_free(&m);
return -1;
}
type = buffer_get_int(&m);
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);
switch (type) {
case MUX_S_SESSION_OPENED:
sid = buffer_get_int(&m);
debug("%s: master session id: %u", __func__, sid);
break;
case MUX_S_PERMISSION_DENIED:
e = buffer_get_string(&m, NULL);
buffer_free(&m);
error("Master refused session request: %s", e);
return -1;
case MUX_S_FAILURE:
e = buffer_get_string(&m, NULL);
buffer_free(&m);
error("%s: session request failed: %s", __func__, e);
return -1;
default:
buffer_free(&m);
error("%s: unexpected response from master 0x%08x",
__func__, type);
return -1;
}
muxclient_request_id++;
signal(SIGHUP, control_client_sighandler);
signal(SIGINT, control_client_sighandler);
signal(SIGTERM, control_client_sighandler);
signal(SIGWINCH, control_client_sigrelay);
rawmode = tty_flag;
if (tty_flag)
enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
/*
* Stick around until the controlee closes the client_fd.
* Before it does, it is expected to write an exit message.
* This process must read the value and wait for the closure of
* the client_fd; if this one closes early, the multiplex master will
* terminate early too (possibly losing data).
*/
for (exitval = 255, exitval_seen = 0;;) {
buffer_clear(&m);
if (mux_client_read_packet(fd, &m) != 0)
break;
type = buffer_get_int(&m);
switch (type) {
case MUX_S_TTY_ALLOC_FAIL:
if ((esid = buffer_get_int(&m)) != sid)
fatal("%s: tty alloc fail on unknown session: "
"my id %u theirs %u",
__func__, sid, esid);
leave_raw_mode(options.request_tty ==
REQUEST_TTY_FORCE);
rawmode = 0;
continue;
case MUX_S_EXIT_MESSAGE:
if ((esid = buffer_get_int(&m)) != sid)
fatal("%s: exit on unknown session: "
"my id %u theirs %u",
__func__, sid, esid);
if (exitval_seen)
fatal("%s: exitval sent twice", __func__);
exitval = buffer_get_int(&m);
exitval_seen = 1;
continue;
default:
e = buffer_get_string(&m, NULL);
fatal("%s: master returned error: %s", __func__, e);
}
}
close(fd);
if (rawmode)
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
if (muxclient_terminate) {
debug2("Exiting on signal %d", muxclient_terminate);
exitval = 255;
} else if (!exitval_seen) {
debug2("Control master terminated unexpectedly");
exitval = 255;
} else
debug2("Received exit status from master %d", exitval);
if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
fprintf(stderr, "Shared connection to %s closed.\r\n", host);
exit(exitval);
}
static int
mux_client_request_stdio_fwd(int fd)
{
Buffer m;
char *e;
u_int type, rid, sid;
int devnull;
debug3("%s: entering", __func__);
if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
error("%s: master alive request failed", __func__);
return -1;
}
signal(SIGPIPE, SIG_IGN);
if (stdin_null_flag) {
if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
fatal("open(/dev/null): %s", strerror(errno));
if (dup2(devnull, STDIN_FILENO) == -1)
fatal("dup2: %s", strerror(errno));
if (devnull > STDERR_FILENO)
close(devnull);
}
buffer_init(&m);
buffer_put_int(&m, MUX_C_NEW_STDIO_FWD);
buffer_put_int(&m, muxclient_request_id);
buffer_put_cstring(&m, ""); /* reserved */
buffer_put_cstring(&m, stdio_forward_host);
buffer_put_int(&m, stdio_forward_port);
if (mux_client_write_packet(fd, &m) != 0)
fatal("%s: write packet: %s", __func__, strerror(errno));
/* Send the stdio file descriptors */
if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
mm_send_fd(fd, STDOUT_FILENO) == -1)
fatal("%s: send fds failed", __func__);
debug3("%s: stdio forward request sent", __func__);
/* Read their reply */
buffer_clear(&m);
if (mux_client_read_packet(fd, &m) != 0) {
error("%s: read from master failed: %s",
__func__, strerror(errno));
buffer_free(&m);
return -1;
}
type = buffer_get_int(&m);
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);
switch (type) {
case MUX_S_SESSION_OPENED:
sid = buffer_get_int(&m);
debug("%s: master session id: %u", __func__, sid);
break;
case MUX_S_PERMISSION_DENIED:
e = buffer_get_string(&m, NULL);
buffer_free(&m);
fatal("Master refused stdio forwarding request: %s", e);
case MUX_S_FAILURE:
e = buffer_get_string(&m, NULL);
buffer_free(&m);
fatal("%s: stdio forwarding request failed: %s", __func__, e);
default:
buffer_free(&m);
error("%s: unexpected response from master 0x%08x",
__func__, type);
return -1;
}
muxclient_request_id++;
signal(SIGHUP, control_client_sighandler);
signal(SIGINT, control_client_sighandler);
signal(SIGTERM, control_client_sighandler);
signal(SIGWINCH, control_client_sigrelay);
/*
* Stick around until the controlee closes the client_fd.
*/
buffer_clear(&m);
if (mux_client_read_packet(fd, &m) != 0) {
if (errno == EPIPE ||
(errno == EINTR && muxclient_terminate != 0))
return 0;
fatal("%s: mux_client_read_packet: %s",
__func__, strerror(errno));
}
fatal("%s: master returned unexpected message %u", __func__, type);
}
static void
mux_client_request_stop_listening(int fd)
{
Buffer m;
char *e;
u_int type, rid;
debug3("%s: entering", __func__);
buffer_init(&m);
buffer_put_int(&m, MUX_C_STOP_LISTENING);
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)
fatal("%s: read from master failed: %s",
__func__, strerror(errno));
type = buffer_get_int(&m);
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);
switch (type) {
case MUX_S_OK:
break;
case MUX_S_PERMISSION_DENIED:
e = buffer_get_string(&m, NULL);
fatal("Master refused stop listening request: %s", e);
case MUX_S_FAILURE:
e = buffer_get_string(&m, NULL);
fatal("%s: stop listening request failed: %s", __func__, e);
default:
fatal("%s: unexpected response from master 0x%08x",
__func__, type);
}
buffer_free(&m);
muxclient_request_id++;
}
/* Multiplex client main loop. */
void
muxclient(const char *path)
{
struct sockaddr_un addr;
socklen_t sun_len;
int sock;
u_int pid;
if (muxclient_command == 0) {
if (stdio_forward_host != NULL)
muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
else
muxclient_command = SSHMUX_COMMAND_OPEN;
}
switch (options.control_master) {
case SSHCTL_MASTER_AUTO:
case SSHCTL_MASTER_AUTO_ASK:
debug("auto-mux: Trying existing master");
/* FALLTHROUGH */
case SSHCTL_MASTER_NO:
break;
default:
return;
}
memset(&addr, '\0', sizeof(addr));
addr.sun_family = AF_UNIX;
sun_len = offsetof(struct sockaddr_un, sun_path) +
strlen(path) + 1;
if (strlcpy(addr.sun_path, path,
sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
fatal("ControlPath too long");
if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
fatal("%s socket(): %s", __func__, strerror(errno));
if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) {
switch (muxclient_command) {
case SSHMUX_COMMAND_OPEN:
case SSHMUX_COMMAND_STDIO_FWD:
break;
default:
fatal("Control socket connect(%.100s): %s", path,
strerror(errno));
}
if (errno == ECONNREFUSED &&
options.control_master != SSHCTL_MASTER_NO) {
debug("Stale control socket %.100s, unlinking", path);
unlink(path);
} else if (errno == ENOENT) {
debug("Control socket \"%.100s\" does not exist", path);
} else {
error("Control socket connect(%.100s): %s", path,
strerror(errno));
}
close(sock);
return;
}
set_nonblock(sock);
if (mux_client_hello_exchange(sock) != 0) {
error("%s: master hello exchange failed", __func__);
close(sock);
return;
}
switch (muxclient_command) {
case SSHMUX_COMMAND_ALIVE_CHECK:
if ((pid = mux_client_request_alive(sock)) == 0)
fatal("%s: master alive check failed", __func__);
fprintf(stderr, "Master running (pid=%d)\r\n", pid);
exit(0);
case SSHMUX_COMMAND_TERMINATE:
mux_client_request_terminate(sock);
fprintf(stderr, "Exit request sent.\r\n");
exit(0);
case SSHMUX_COMMAND_FORWARD:
if (mux_client_forwards(sock, 0) != 0)
fatal("%s: master forward request failed", __func__);
exit(0);
case SSHMUX_COMMAND_OPEN:
if (mux_client_forwards(sock, 0) != 0) {
error("%s: master forward request failed", __func__);
return;
}
mux_client_request_session(sock);
return;
case SSHMUX_COMMAND_STDIO_FWD:
mux_client_request_stdio_fwd(sock);
exit(0);
case SSHMUX_COMMAND_STOP:
mux_client_request_stop_listening(sock);
fprintf(stderr, "Stop listening request sent.\r\n");
exit(0);
case SSHMUX_COMMAND_CANCEL_FWD:
if (mux_client_forwards(sock, 1) != 0)
error("%s: master cancel forward request failed",
__func__);
exit(0);
default:
fatal("unrecognised muxclient_command %d", muxclient_command);
}
}
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