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mux.c
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/* $OpenBSD: mux.c,v 1.103 2024/10/12 10:50:37 jsg 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 */
#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.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 "sshbuf.h"
#include "channels.h"
#include "msg.h"
#include "packet.h"
#include "monitor_fdpass.h"
#include "sshpty.h"
#include "sshkey.h"
#include "readconf.h"
#include "clientloop.h"
#include "ssherr.h"
/* from ssh.c */
extern int tty_flag;
extern Options options;
extern char *host;
extern struct sshbuf *command;
extern volatile sig_atomic_t quit_pending;
/* 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;
struct sshbuf *cmd;
char *term;
struct termios tio;
char **env;
u_int rid;
};
/* Context for stdio fwd open confirmation callback */
struct mux_stdio_confirm_ctx {
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_C_PROXY 0x1000000f
#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
#define MUX_S_PROXY 0x8000000f
/* 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(struct ssh *, int, int, void *);
static void mux_stdio_confirm(struct ssh *, int, int, void *);
static int mux_master_process_hello(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_new_session(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_alive_check(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_terminate(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_open_fwd(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_close_fwd(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_stdio_fwd(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_stop_listening(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static int mux_master_process_proxy(struct ssh *, u_int,
Channel *, struct sshbuf *, struct sshbuf *);
static const struct {
u_int type;
int (*handler)(struct ssh *, u_int, Channel *,
struct sshbuf *, struct sshbuf *);
} mux_master_handlers[] = {
{ MUX_MSG_HELLO, mux_master_process_hello },
{ MUX_C_NEW_SESSION, mux_master_process_new_session },
{ MUX_C_ALIVE_CHECK, mux_master_process_alive_check },
{ MUX_C_TERMINATE, mux_master_process_terminate },
{ MUX_C_OPEN_FWD, mux_master_process_open_fwd },
{ MUX_C_CLOSE_FWD, mux_master_process_close_fwd },
{ MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd },
{ MUX_C_STOP_LISTENING, mux_master_process_stop_listening },
{ MUX_C_PROXY, mux_master_process_proxy },
{ 0, NULL }
};
/* Cleanup callback fired on closure of mux client _session_ channel */
static void
mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused)
{
Channel *cc, *c = channel_by_id(ssh, cid);
debug3_f("entering for channel %d", cid);
if (c == NULL)
fatal_f("channel_by_id(%i) == NULL", cid);
if (c->ctl_chan != -1) {
if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
fatal_f("channel %d missing control channel %d",
c->self, c->ctl_chan);
c->ctl_chan = -1;
cc->ctl_child_id = 0;
cc->have_ctl_child_id = 0;
chan_rcvd_oclose(ssh, cc);
}
channel_cancel_cleanup(ssh, c->self);
}
/* Cleanup callback fired on closure of mux client _control_ channel */
static void
mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused)
{
Channel *sc, *c = channel_by_id(ssh, cid);
debug3_f("entering for channel %d", cid);
if (c == NULL)
fatal_f("channel_by_id(%i) == NULL", cid);
if (c->have_ctl_child_id) {
if ((sc = channel_by_id(ssh, c->ctl_child_id)) == NULL)
fatal_f("channel %d missing session channel %u",
c->self, c->ctl_child_id);
c->ctl_child_id = 0;
c->have_ctl_child_id = 0;
sc->ctl_chan = -1;
if (sc->type != SSH_CHANNEL_OPEN &&
sc->type != SSH_CHANNEL_OPENING) {
debug2_f("channel %d: not open", sc->self);
chan_mark_dead(ssh, sc);
} else {
if (sc->istate == CHAN_INPUT_OPEN)
chan_read_failed(ssh, sc);
if (sc->ostate == CHAN_OUTPUT_OPEN)
chan_write_failed(ssh, sc);
}
}
channel_cancel_cleanup(ssh, c->self);
}
/* Check mux client environment variables before passing them to mux master. */
static int
env_permitted(const char *env)
{
u_int i;
int 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_f("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
mux_master_process_hello(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
u_int ver;
struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
int r;
if (state == NULL)
fatal_f("channel %d: c->mux_ctx == NULL", c->self);
if (state->hello_rcvd) {
error_f("HELLO received twice");
return -1;
}
if ((r = sshbuf_get_u32(m, &ver)) != 0) {
error_fr(r, "parse");
return -1;
}
if (ver != SSHMUX_VER) {
error_f("unsupported multiplexing protocol version %u "
"(expected %u)", ver, SSHMUX_VER);
return -1;
}
debug2_f("channel %d client version %u", c->self, ver);
/* No extensions are presently defined */
while (sshbuf_len(m) > 0) {
char *name = NULL;
size_t value_len = 0;
if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
(r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) {
error_fr(r, "parse extension");
return -1;
}
debug2_f("Unrecognised extension \"%s\" length %zu",
name, value_len);
free(name);
}
state->hello_rcvd = 1;
return 0;
}
/* Enqueue a "ok" response to the reply buffer */
static void
reply_ok(struct sshbuf *reply, u_int rid)
{
int r;
if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 ||
(r = sshbuf_put_u32(reply, rid)) != 0)
fatal_fr(r, "reply");
}
/* Enqueue an error response to the reply buffer */
static void
reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg)
{
int r;
if ((r = sshbuf_put_u32(reply, type)) != 0 ||
(r = sshbuf_put_u32(reply, rid)) != 0 ||
(r = sshbuf_put_cstring(reply, msg)) != 0)
fatal_fr(r, "reply");
}
static int
mux_master_process_new_session(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
Channel *nc;
struct mux_session_confirm_ctx *cctx;
char *cmd, *cp;
u_int i, j, env_len, escape_char, window, packetmax;
int r, new_fd[3];
/* Reply for SSHMUX_COMMAND_OPEN */
cctx = xcalloc(1, sizeof(*cctx));
cctx->term = NULL;
cctx->rid = rid;
cmd = NULL;
cctx->env = NULL;
env_len = 0;
if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
(r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 ||
(r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 ||
(r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 ||
(r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 ||
(r = sshbuf_get_u32(m, &escape_char)) != 0 ||
(r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 ||
(r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) {
malf:
free(cmd);
for (j = 0; j < env_len; j++)
free(cctx->env[j]);
free(cctx->env);
free(cctx->term);
free(cctx);
error_f("malformed message");
return -1;
}
#define MUX_MAX_ENV_VARS 4096
while (sshbuf_len(m) > 0) {
if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0)
goto malf;
if (!env_permitted(cp)) {
free(cp);
continue;
}
cctx->env = xreallocarray(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_f(">%d environment variables received, "
"ignoring additional", MUX_MAX_ENV_VARS);
break;
}
}
debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, "
"term \"%s\", cmd \"%s\", env %u", c->self,
cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
cctx->want_subsys, cctx->term, cmd, env_len);
if ((cctx->cmd = sshbuf_new()) == NULL)
fatal_f("sshbuf_new");
if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0)
fatal_fr(r, "sshbuf_put");
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_f("failed to receive fd %d from client", 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);
sshbuf_free(cctx->cmd);
free(cctx);
reply_error(reply, MUX_S_FAILURE, rid,
"did not receive file descriptors");
return -1;
}
}
debug3_f("got fds stdin %d, stdout %d, stderr %d",
new_fd[0], new_fd[1], new_fd[2]);
/* XXX support multiple child sessions in future */
if (c->have_ctl_child_id) {
debug2_f("session already open");
reply_error(reply, MUX_S_FAILURE, rid,
"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);
}
sshbuf_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_f("session refused by user");
reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
"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_f("tcgetattr: %s", strerror(errno));
window = CHAN_SES_WINDOW_DEFAULT;
packetmax = CHAN_SES_PACKET_DEFAULT;
if (cctx->want_tty) {
window >>= 1;
packetmax >>= 1;
}
nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
new_fd[0], new_fd[1], new_fd[2], window, packetmax,
CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO);
nc->ctl_chan = c->self; /* link session -> control channel */
c->ctl_child_id = nc->self; /* link control -> session channel */
c->have_ctl_child_id = 1;
if (cctx->want_tty && escape_char != 0xffffffff) {
channel_register_filter(ssh, nc->self,
client_simple_escape_filter, NULL,
client_filter_cleanup,
client_new_escape_filter_ctx((int)escape_char));
}
debug2_f("channel_new: %d linked to control channel %d",
nc->self, nc->ctl_chan);
channel_send_open(ssh, nc->self);
channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx);
c->mux_pause = 1; /* stop handling messages until open_confirm done */
channel_register_cleanup(ssh, nc->self,
mux_master_session_cleanup_cb, 1);
/* reply is deferred, sent by mux_session_confirm */
return 0;
}
static int
mux_master_process_alive_check(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
int r;
debug2_f("channel %d: alive check", c->self);
/* prepare reply */
if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 ||
(r = sshbuf_put_u32(reply, rid)) != 0 ||
(r = sshbuf_put_u32(reply, (u_int)getpid())) != 0)
fatal_fr(r, "reply");
return 0;
}
static int
mux_master_process_terminate(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
debug2_f("channel %d: terminate request", 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_f("termination refused by user");
reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
"Permission denied");
return 0;
}
}
quit_pending = 1;
reply_ok(reply, rid);
/* XXX exit happens too soon - message never makes it to client */
return 0;
}
static char *
format_forward(u_int ftype, struct Forward *fwd)
{
char *ret;
switch (ftype) {
case MUX_FWD_LOCAL:
xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
(fwd->listen_path != NULL) ? fwd->listen_path :
(fwd->listen_host == NULL) ?
(options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
fwd->listen_host, fwd->listen_port,
(fwd->connect_path != NULL) ? fwd->connect_path :
fwd->connect_host, fwd->connect_port);
break;
case MUX_FWD_DYNAMIC:
xasprintf(&ret, "dynamic forward %.200s:%d -> *",
(fwd->listen_host == NULL) ?
(options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
fwd->listen_host, fwd->listen_port);
break;
case MUX_FWD_REMOTE:
xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
(fwd->listen_path != NULL) ? fwd->listen_path :
(fwd->listen_host == NULL) ?
"LOCALHOST" : fwd->listen_host,
fwd->listen_port,
(fwd->connect_path != NULL) ? fwd->connect_path :
fwd->connect_host, fwd->connect_port);
break;
default:
fatal_f("unknown forward type %u", 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(struct Forward *a, struct Forward *b)
{
if (!compare_host(a->listen_host, b->listen_host))
return 0;
if (!compare_host(a->listen_path, b->listen_path))
return 0;
if (a->listen_port != b->listen_port)
return 0;
if (!compare_host(a->connect_host, b->connect_host))
return 0;
if (!compare_host(a->connect_path, b->connect_path))
return 0;
if (a->connect_port != b->connect_port)
return 0;
return 1;
}
static void
mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
{
struct mux_channel_confirm_ctx *fctx = ctxt;
char *failmsg = NULL;
struct Forward *rfwd;
Channel *c;
struct sshbuf *out;
u_int port;
int r;
if ((c = channel_by_id(ssh, fctx->cid)) == NULL) {
/* no channel for reply */
error_f("unknown channel");
return;
}
if ((out = sshbuf_new()) == NULL)
fatal_f("sshbuf_new");
if (fctx->fid >= options.num_remote_forwards ||
(options.remote_forwards[fctx->fid].connect_path == NULL &&
options.remote_forwards[fctx->fid].connect_host == NULL)) {
xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
goto fail;
}
rfwd = &options.remote_forwards[fctx->fid];
debug_f("%s for: listen %d, connect %s:%d",
type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
rfwd->connect_host, rfwd->connect_port);
if (type == SSH2_MSG_REQUEST_SUCCESS) {
if (rfwd->listen_port == 0) {
if ((r = sshpkt_get_u32(ssh, &port)) != 0)
fatal_fr(r, "parse port");
if (port > 65535) {
fatal("Invalid allocated port %u for "
"mux remote forward to %s:%d", port,
rfwd->connect_host, rfwd->connect_port);
}
rfwd->allocated_port = (int)port;
debug("Allocated port %u for mux remote forward"
" to %s:%d", rfwd->allocated_port,
rfwd->connect_host, rfwd->connect_port);
if ((r = sshbuf_put_u32(out,
MUX_S_REMOTE_PORT)) != 0 ||
(r = sshbuf_put_u32(out, fctx->rid)) != 0 ||
(r = sshbuf_put_u32(out,
rfwd->allocated_port)) != 0)
fatal_fr(r, "reply");
channel_update_permission(ssh, rfwd->handle,
rfwd->allocated_port);
} else {
reply_ok(out, fctx->rid);
}
goto out;
} else {
if (rfwd->listen_port == 0)
channel_update_permission(ssh, rfwd->handle, -1);
if (rfwd->listen_path != NULL)
xasprintf(&failmsg, "remote port forwarding failed for "
"listen path %s", rfwd->listen_path);
else
xasprintf(&failmsg, "remote port forwarding failed for "
"listen port %d", rfwd->listen_port);
debug2_f("clearing registered forwarding for listen %d, "
"connect %s:%d", rfwd->listen_port,
rfwd->connect_path ? rfwd->connect_path :
rfwd->connect_host, rfwd->connect_port);
free(rfwd->listen_host);
free(rfwd->listen_path);
free(rfwd->connect_host);
free(rfwd->connect_path);
memset(rfwd, 0, sizeof(*rfwd));
}
fail:
error_f("%s", failmsg);
reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg);
free(failmsg);
out:
if ((r = sshbuf_put_stringb(c->output, out)) != 0)
fatal_fr(r, "enqueue");
sshbuf_free(out);
if (c->mux_pause <= 0)
fatal_f("mux_pause %d", c->mux_pause);
c->mux_pause = 0; /* start processing messages again */
}
static int
mux_master_process_open_fwd(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
struct Forward fwd;
char *fwd_desc = NULL;
char *listen_addr, *connect_addr;
u_int ftype;
u_int lport, cport;
int r, i, ret = 0, freefwd = 1;
memset(&fwd, 0, sizeof(fwd));
/* XXX - lport/cport check redundant */
if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
(r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
(r = sshbuf_get_u32(m, &lport)) != 0 ||
(r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
(r = sshbuf_get_u32(m, &cport)) != 0 ||
(lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
(cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
error_f("malformed message");
ret = -1;
goto out;
}
if (*listen_addr == '\0') {
free(listen_addr);
listen_addr = NULL;
}
if (*connect_addr == '\0') {
free(connect_addr);
connect_addr = NULL;
}
memset(&fwd, 0, sizeof(fwd));
fwd.listen_port = lport;
if (fwd.listen_port == PORT_STREAMLOCAL)
fwd.listen_path = listen_addr;
else
fwd.listen_host = listen_addr;
fwd.connect_port = cport;
if (fwd.connect_port == PORT_STREAMLOCAL)
fwd.connect_path = connect_addr;
else
fwd.connect_host = connect_addr;
debug2_f("channel %d: request %s", c->self,
(fwd_desc = format_forward(ftype, &fwd)));
if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
ftype != MUX_FWD_DYNAMIC) {
logit_f("invalid forwarding type %u", ftype);
invalid:
free(listen_addr);
free(connect_addr);
reply_error(reply, MUX_S_FAILURE, rid,
"Invalid forwarding request");
return 0;
}
if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
logit_f("streamlocal and dynamic forwards "
"are mutually exclusive");
goto invalid;
}
if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
logit_f("invalid listen port %u", fwd.listen_port);
goto invalid;
}
if ((fwd.connect_port != PORT_STREAMLOCAL &&
fwd.connect_port >= 65536) ||
(ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE &&
fwd.connect_port == 0)) {
logit_f("invalid connect port %u",
fwd.connect_port);
goto invalid;
}
if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL &&
fwd.connect_path == NULL) {
logit_f("missing connect host");
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_f("found existing forwarding");
reply_ok(reply, 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))
continue;
if (fwd.listen_port != 0)
goto exists;
debug2_f("found allocated port");
if ((r = sshbuf_put_u32(reply,
MUX_S_REMOTE_PORT)) != 0 ||
(r = sshbuf_put_u32(reply, rid)) != 0 ||
(r = sshbuf_put_u32(reply,
options.remote_forwards[i].allocated_port)) != 0)
fatal_fr(r, "reply FWD_REMOTE");
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_f("forwarding refused by user");
reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
"Permission denied");
goto out;
}
}
if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
if (!channel_setup_local_fwd_listener(ssh, &fwd,
&options.fwd_opts)) {
fail:
logit_f("requested %s failed", fwd_desc);
reply_error(reply, MUX_S_FAILURE, rid,
"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(ssh, &fwd);
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;
}
reply_ok(reply, rid);
out:
free(fwd_desc);
if (freefwd) {
free(fwd.listen_host);
free(fwd.listen_path);
free(fwd.connect_host);
free(fwd.connect_path);
}
return ret;
}
static int
mux_master_process_close_fwd(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
struct Forward fwd, *found_fwd;
char *fwd_desc = NULL;
const char *error_reason = NULL;
char *listen_addr = NULL, *connect_addr = NULL;
u_int ftype;
int r, i, ret = 0;
u_int lport, cport;
memset(&fwd, 0, sizeof(fwd));
if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
(r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
(r = sshbuf_get_u32(m, &lport)) != 0 ||
(r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
(r = sshbuf_get_u32(m, &cport)) != 0 ||
(lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
(cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
error_f("malformed message");
ret = -1;
goto out;
}
if (*listen_addr == '\0') {
free(listen_addr);
listen_addr = NULL;
}
if (*connect_addr == '\0') {
free(connect_addr);
connect_addr = NULL;
}
memset(&fwd, 0, sizeof(fwd));
fwd.listen_port = lport;
if (fwd.listen_port == PORT_STREAMLOCAL)
fwd.listen_path = listen_addr;
else
fwd.listen_host = listen_addr;
fwd.connect_port = cport;
if (fwd.connect_port == PORT_STREAMLOCAL)
fwd.connect_path = connect_addr;
else
fwd.connect_host = connect_addr;
debug2_f("channel %d: request cancel %s", 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 use the actual listen port.
*/
if (channel_request_rforward_cancel(ssh, found_fwd) == -1)
error_reason = "port not in permitted opens";
} else { /* local and dynamic forwards */
/* Ditto */
if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
&options.fwd_opts) == -1)
error_reason = "port not found";
}
if (error_reason != NULL)
reply_error(reply, MUX_S_FAILURE, rid, error_reason);
else {
reply_ok(reply, rid);
free(found_fwd->listen_host);
free(found_fwd->listen_path);
free(found_fwd->connect_host);
free(found_fwd->connect_path);
found_fwd->listen_host = found_fwd->connect_host = NULL;
found_fwd->listen_path = found_fwd->connect_path = NULL;
found_fwd->listen_port = found_fwd->connect_port = 0;
}
out:
free(fwd_desc);
free(listen_addr);
free(connect_addr);
return ret;
}
static int
mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid,
Channel *c, struct sshbuf *m, struct sshbuf *reply)
{
Channel *nc;
char *chost = NULL;
u_int _cport, i, j;
int ok = 0, cport, r, new_fd[2];
struct mux_stdio_confirm_ctx *cctx;
if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
(r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
(r = sshbuf_get_u32(m, &_cport)) != 0) {
free(chost);
error_f("malformed message");
return -1;
}
if (_cport == (u_int)PORT_STREAMLOCAL)
cport = PORT_STREAMLOCAL;
else if (_cport <= INT_MAX)
cport = (int)_cport;
else {
free(chost);
error_f("invalid port 0x%x", _cport);
return -1;
}
debug2_f("channel %d: stdio fwd to %s:%d", 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_f("failed to receive fd %d from client", i);
for (j = 0; j < i; j++)
close(new_fd[j]);
free(chost);
/* prepare reply */
reply_error(reply, MUX_S_FAILURE, rid,
"did not receive file descriptors");
return -1;
}
}