1 /* $OpenBSD: serverloop.c,v 1.231 2022/01/22 00:49:34 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Server main loop for handling the interactive session.
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
14 * SSH2 support by Markus Friedl.
15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 #include <sys/types.h>
42 #include <sys/socket.h>
43 #ifdef HAVE_SYS_TIME_H
44 # include <sys/time.h>
47 #include <netinet/in.h>
62 #include "openbsd-compat/sys-queue.h"
81 #include "auth-options.h"
82 #include "serverloop.h"
85 extern ServerOptions options;
88 extern Authctxt *the_authctxt;
89 extern struct sshauthopt *auth_opts;
90 extern int use_privsep;
92 static int no_more_sessions = 0; /* Disallow further sessions. */
94 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */
96 /* Cleanup on signals (!use_privsep case only) */
97 static volatile sig_atomic_t received_sigterm = 0;
100 static void server_init_dispatch(struct ssh *);
102 /* requested tunnel forwarding interface(s), shared with session.c */
103 char *tun_fwd_ifnames = NULL;
105 /* returns 1 if bind to specified port by specified user is permitted */
107 bind_permitted(int port, uid_t uid)
110 return 1; /* allow system to decide */
111 if (port < IPPORT_RESERVED && uid != 0)
118 sigchld_handler(int sig)
120 child_terminated = 1;
125 sigterm_handler(int sig)
127 received_sigterm = sig;
131 client_alive_check(struct ssh *ssh)
136 /* timeout, check to see how many we have had */
137 if (options.client_alive_count_max > 0 &&
138 ssh_packet_inc_alive_timeouts(ssh) >
139 options.client_alive_count_max) {
140 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
141 logit("Timeout, client not responding from %s", remote_id);
146 * send a bogus global/channel request with "wantreply",
147 * we should get back a failure
149 if ((channel_id = channel_find_open(ssh)) == -1) {
150 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
151 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com"))
153 (r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */
154 fatal_fr(r, "compose");
156 channel_request_start(ssh, channel_id,
157 "keepalive@openssh.com", 1);
159 if ((r = sshpkt_send(ssh)) != 0)
164 * Sleep in ppoll() until we can do something.
165 * Optionally, a maximum time can be specified for the duration of
166 * the wait (0 = infinite).
169 wait_until_can_do_something(struct ssh *ssh,
170 int connection_in, int connection_out, struct pollfd **pfdp,
171 u_int *npfd_allocp, u_int *npfd_activep, u_int64_t max_time_ms,
172 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp)
174 struct timespec ts, *tsp;
176 time_t minwait_secs = 0;
177 int client_alive_scheduled = 0;
179 /* time we last heard from the client OR sent a keepalive */
180 static time_t last_client_time;
182 *conn_in_readyp = *conn_out_readyp = 0;
184 /* Prepare channel poll. First two pollfd entries are reserved */
185 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep,
187 if (*npfd_activep < 2)
188 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
190 /* XXX need proper deadline system for rekey/client alive */
191 if (minwait_secs != 0)
192 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000);
195 * if using client_alive, set the max timeout accordingly,
196 * and indicate that this particular timeout was for client
197 * alive by setting the client_alive_scheduled flag.
199 * this could be randomized somewhat to make traffic
200 * analysis more difficult, but we're not doing it yet.
202 if (options.client_alive_interval) {
203 uint64_t keepalive_ms =
204 (uint64_t)options.client_alive_interval * 1000;
206 if (max_time_ms == 0 || max_time_ms > keepalive_ms) {
207 max_time_ms = keepalive_ms;
208 client_alive_scheduled = 1;
210 if (last_client_time == 0)
211 last_client_time = monotime();
215 /* wrong: bad condition XXX */
216 if (channel_not_very_much_buffered_data())
218 /* Monitor client connection on reserved pollfd entries */
219 (*pfdp)[0].fd = connection_in;
220 (*pfdp)[0].events = POLLIN;
221 (*pfdp)[1].fd = connection_out;
222 (*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;
225 * If child has terminated and there is enough buffer space to read
226 * from it, then read as much as is available and exit.
228 if (child_terminated && ssh_packet_not_very_much_data_to_write(ssh))
229 if (max_time_ms == 0 || client_alive_scheduled)
232 if (max_time_ms == 0)
235 ts.tv_sec = max_time_ms / 1000;
236 ts.tv_nsec = 1000000 * (max_time_ms % 1000);
240 /* Wait for something to happen, or the timeout to expire. */
241 ret = ppoll(*pfdp, *npfd_activep, tsp, sigsetp);
244 for (p = 0; p < *npfd_activep; p++)
245 (*pfdp)[p].revents = 0;
247 fatal_f("ppoll: %.100s", strerror(errno));
251 *conn_in_readyp = (*pfdp)[0].revents != 0;
252 *conn_out_readyp = (*pfdp)[1].revents != 0;
254 if (client_alive_scheduled) {
255 time_t now = monotime();
258 * If the ppoll timed out, or returned for some other reason
259 * but we haven't heard from the client in time, send keepalive.
261 if (ret == 0 || (last_client_time != 0 && last_client_time +
262 options.client_alive_interval <= now)) {
263 client_alive_check(ssh);
264 last_client_time = now;
265 } else if (*conn_in_readyp)
266 last_client_time = now;
271 * Processes input from the client and the program. Input data is stored
272 * in buffers and processed later.
275 process_input(struct ssh *ssh, int connection_in)
279 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
280 return 0; /* success */
281 if (r == SSH_ERR_SYSTEM_ERROR) {
282 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
284 if (errno == EPIPE) {
285 verbose("Connection closed by %.100s port %d",
286 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
289 verbose("Read error from remote host %s port %d: %s",
290 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
298 * Sends data from internal buffers to client program stdin.
301 process_output(struct ssh *ssh, int connection_out)
305 /* Send any buffered packet data to the client. */
306 if ((r = ssh_packet_write_poll(ssh)) != 0) {
307 sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll",
313 process_buffered_input_packets(struct ssh *ssh)
315 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL);
319 collect_children(struct ssh *ssh)
324 if (child_terminated) {
325 debug("Received SIGCHLD.");
326 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
327 (pid == -1 && errno == EINTR))
329 session_close_by_pid(ssh, pid, status);
330 child_terminated = 0;
335 server_loop2(struct ssh *ssh, Authctxt *authctxt)
337 struct pollfd *pfd = NULL;
338 u_int npfd_alloc = 0, npfd_active = 0;
339 int r, conn_in_ready, conn_out_ready;
340 u_int connection_in, connection_out;
341 u_int64_t rekey_timeout_ms = 0;
342 sigset_t bsigset, osigset;
344 debug("Entering interactive session for SSH2.");
346 if (sigemptyset(&bsigset) == -1 || sigaddset(&bsigset, SIGCHLD) == -1)
347 error_f("bsigset setup: %s", strerror(errno));
348 ssh_signal(SIGCHLD, sigchld_handler);
349 child_terminated = 0;
350 connection_in = ssh_packet_get_connection_in(ssh);
351 connection_out = ssh_packet_get_connection_out(ssh);
354 ssh_signal(SIGTERM, sigterm_handler);
355 ssh_signal(SIGINT, sigterm_handler);
356 ssh_signal(SIGQUIT, sigterm_handler);
359 server_init_dispatch(ssh);
362 process_buffered_input_packets(ssh);
364 if (!ssh_packet_is_rekeying(ssh) &&
365 ssh_packet_not_very_much_data_to_write(ssh))
366 channel_output_poll(ssh);
367 if (options.rekey_interval > 0 &&
368 !ssh_packet_is_rekeying(ssh)) {
369 rekey_timeout_ms = ssh_packet_get_rekey_timeout(ssh) *
372 rekey_timeout_ms = 0;
376 * Block SIGCHLD while we check for dead children, then pass
377 * the old signal mask through to ppoll() so that it'll wake
378 * up immediately if a child exits after we've called waitpid().
380 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1)
381 error_f("bsigset sigprocmask: %s", strerror(errno));
382 collect_children(ssh);
383 wait_until_can_do_something(ssh, connection_in, connection_out,
384 &pfd, &npfd_alloc, &npfd_active, rekey_timeout_ms, &osigset,
385 &conn_in_ready, &conn_out_ready);
386 if (sigprocmask(SIG_UNBLOCK, &bsigset, &osigset) == -1)
387 error_f("osigset sigprocmask: %s", strerror(errno));
389 if (received_sigterm) {
390 logit("Exiting on signal %d", (int)received_sigterm);
391 /* Clean up sessions, utmp, etc. */
395 if (!ssh_packet_is_rekeying(ssh))
396 channel_after_poll(ssh, pfd, npfd_active);
398 process_input(ssh, connection_in) < 0)
400 /* A timeout may have triggered rekeying */
401 if ((r = ssh_packet_check_rekey(ssh)) != 0)
402 fatal_fr(r, "cannot start rekeying");
404 process_output(ssh, connection_out);
406 collect_children(ssh);
409 /* free all channels, no more reads and writes */
410 channel_free_all(ssh);
412 /* free remaining sessions, e.g. remove wtmp entries */
413 session_destroy_all(ssh, NULL);
417 server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh)
419 debug("Got %d/%u for keepalive", type, seq);
421 * reset timeout, since we got a sane answer from the client.
422 * even if this was generated by something other than
423 * the bogus CHANNEL_REQUEST we send for keepalives.
425 ssh_packet_set_alive_timeouts(ssh, 0);
430 server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
433 char *target = NULL, *originator = NULL;
434 u_int target_port = 0, originator_port = 0;
437 if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
438 (r = sshpkt_get_u32(ssh, &target_port)) != 0 ||
439 (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
440 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
441 (r = sshpkt_get_end(ssh)) != 0)
442 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
443 if (target_port > 0xFFFF) {
444 error_f("invalid target port");
445 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
448 if (originator_port > 0xFFFF) {
449 error_f("invalid originator port");
450 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
454 debug_f("originator %s port %u, target %s port %u",
455 originator, originator_port, target, target_port);
457 /* XXX fine grained permissions */
458 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
459 auth_opts->permit_port_forwarding_flag &&
460 !options.disable_forwarding) {
461 c = channel_connect_to_port(ssh, target, target_port,
462 "direct-tcpip", "direct-tcpip", reason, errmsg);
464 logit("refused local port forward: "
465 "originator %s port %d, target %s port %d",
466 originator, originator_port, target, target_port);
468 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
478 server_request_direct_streamlocal(struct ssh *ssh)
481 char *target = NULL, *originator = NULL;
482 u_int originator_port = 0;
483 struct passwd *pw = the_authctxt->pw;
486 if (pw == NULL || !the_authctxt->valid)
487 fatal_f("no/invalid user");
489 if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
490 (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
491 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
492 (r = sshpkt_get_end(ssh)) != 0)
493 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
494 if (originator_port > 0xFFFF) {
495 error_f("invalid originator port");
499 debug_f("originator %s port %d, target %s",
500 originator, originator_port, target);
502 /* XXX fine grained permissions */
503 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
504 auth_opts->permit_port_forwarding_flag &&
505 !options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) {
506 c = channel_connect_to_path(ssh, target,
507 "direct-streamlocal@openssh.com", "direct-streamlocal");
509 logit("refused streamlocal port forward: "
510 "originator %s port %d, target %s",
511 originator, originator_port, target);
521 server_request_tun(struct ssh *ssh)
526 char *tmp, *ifname = NULL;
528 if ((r = sshpkt_get_u32(ssh, &mode)) != 0)
529 sshpkt_fatal(ssh, r, "%s: parse mode", __func__);
531 case SSH_TUNMODE_POINTOPOINT:
532 case SSH_TUNMODE_ETHERNET:
535 ssh_packet_send_debug(ssh, "Unsupported tunnel device mode.");
538 if ((options.permit_tun & mode) == 0) {
539 ssh_packet_send_debug(ssh, "Server has rejected tunnel device "
544 if ((r = sshpkt_get_u32(ssh, &tun)) != 0)
545 sshpkt_fatal(ssh, r, "%s: parse device", __func__);
547 debug_f("invalid tun");
550 if (auth_opts->force_tun_device != -1) {
551 if (tun != SSH_TUNID_ANY &&
552 auth_opts->force_tun_device != (int)tun)
554 tun = auth_opts->force_tun_device;
556 sock = tun_open(tun, mode, &ifname);
559 debug("Tunnel forwarding using interface %s", ifname);
561 c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1,
562 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
564 #if defined(SSH_TUN_FILTER)
565 if (mode == SSH_TUNMODE_POINTOPOINT)
566 channel_register_filter(ssh, c->self, sys_tun_infilter,
567 sys_tun_outfilter, NULL, NULL);
571 * Update the list of names exposed to the session
572 * XXX remove these if the tunnels are closed (won't matter
573 * much if they are already in the environment though)
575 tmp = tun_fwd_ifnames;
576 xasprintf(&tun_fwd_ifnames, "%s%s%s",
577 tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames,
578 tun_fwd_ifnames == NULL ? "" : ",",
585 ssh_packet_send_debug(ssh, "Failed to open the tunnel device.");
590 server_request_session(struct ssh *ssh)
595 debug("input_session_request");
596 if ((r = sshpkt_get_end(ssh)) != 0)
597 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
599 if (no_more_sessions) {
600 ssh_packet_disconnect(ssh, "Possible attack: attempt to open a "
601 "session after additional sessions disabled");
605 * A server session has no fd to read or write until a
606 * CHANNEL_REQUEST for a shell is made, so we set the type to
607 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all
608 * CHANNEL_REQUEST messages is registered.
610 c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL,
611 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
612 0, "server-session", 1);
613 if (session_open(the_authctxt, c->self) != 1) {
614 debug("session open failed, free channel %d", c->self);
615 channel_free(ssh, c);
618 channel_register_cleanup(ssh, c->self, session_close_by_channel, 0);
623 server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
627 const char *errmsg = NULL;
628 int r, reason = SSH2_OPEN_CONNECT_FAILED;
629 u_int rchan = 0, rmaxpack = 0, rwindow = 0;
631 if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 ||
632 (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
633 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
634 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
635 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
636 debug_f("ctype %s rchan %u win %u max %u",
637 ctype, rchan, rwindow, rmaxpack);
639 if (strcmp(ctype, "session") == 0) {
640 c = server_request_session(ssh);
641 } else if (strcmp(ctype, "direct-tcpip") == 0) {
642 c = server_request_direct_tcpip(ssh, &reason, &errmsg);
643 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
644 c = server_request_direct_streamlocal(ssh);
645 } else if (strcmp(ctype, "tun@openssh.com") == 0) {
646 c = server_request_tun(ssh);
649 debug_f("confirm %s", ctype);
650 c->remote_id = rchan;
651 c->have_remote_id = 1;
652 c->remote_window = rwindow;
653 c->remote_maxpacket = rmaxpack;
654 if (c->type != SSH_CHANNEL_CONNECTING) {
655 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
656 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
657 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
658 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
659 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
660 (r = sshpkt_send(ssh)) != 0) {
662 "%s: send open confirm", __func__);
666 debug_f("failure %s", ctype);
667 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
668 (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
669 (r = sshpkt_put_u32(ssh, reason)) != 0 ||
670 (r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 ||
671 (r = sshpkt_put_cstring(ssh, "")) != 0 ||
672 (r = sshpkt_send(ssh)) != 0) {
674 "%s: send open failure", __func__);
682 server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
684 struct sshbuf *resp = NULL;
685 struct sshbuf *sigbuf = NULL;
686 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
687 int r, ndx, success = 0;
689 const char *sigalg, *kex_rsa_sigalg = NULL;
693 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
694 fatal_f("sshbuf_new");
695 if (sshkey_type_plain(sshkey_type_from_name(
696 ssh->kex->hostkey_alg)) == KEY_RSA)
697 kex_rsa_sigalg = ssh->kex->hostkey_alg;
698 while (ssh_packet_remaining(ssh) > 0) {
701 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
702 (r = sshkey_from_blob(blob, blen, &key)) != 0) {
703 error_fr(r, "parse key");
707 * Better check that this is actually one of our hostkeys
708 * before attempting to sign anything with it.
710 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
711 error_f("unknown host %s key", sshkey_type(key));
715 * XXX refactor: make kex->sign just use an index rather
716 * than passing in public and private keys
718 if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
719 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
720 error_f("can't retrieve hostkey %d", ndx);
723 sshbuf_reset(sigbuf);
727 * For RSA keys, prefer to use the signature type negotiated
728 * during KEX to the default (SHA1).
731 if (sshkey_type_plain(key->type) == KEY_RSA) {
732 if (kex_rsa_sigalg != NULL)
733 sigalg = kex_rsa_sigalg;
734 else if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
735 sigalg = "rsa-sha2-512";
736 else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
737 sigalg = "rsa-sha2-256";
739 debug3_f("sign %s key (index %d) using sigalg %s",
740 sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg);
741 if ((r = sshbuf_put_cstring(sigbuf,
742 "hostkeys-prove-00@openssh.com")) != 0 ||
743 (r = sshbuf_put_stringb(sigbuf,
744 ssh->kex->session_id)) != 0 ||
745 (r = sshkey_puts(key, sigbuf)) != 0 ||
746 (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
747 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), sigalg)) != 0 ||
748 (r = sshbuf_put_string(resp, sig, slen)) != 0) {
749 error_fr(r, "assemble signature");
755 resp = NULL; /* don't free it */
766 server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
769 u_char want_reply = 0;
770 int r, success = 0, allocated_listen_port = 0;
772 struct sshbuf *resp = NULL;
773 struct passwd *pw = the_authctxt->pw;
776 memset(&fwd, 0, sizeof(fwd));
777 if (pw == NULL || !the_authctxt->valid)
778 fatal_f("no/invalid user");
780 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
781 (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
782 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
783 debug_f("rtype %s want_reply %d", rtype, want_reply);
785 /* -R style forwarding */
786 if (strcmp(rtype, "tcpip-forward") == 0) {
787 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
788 (r = sshpkt_get_u32(ssh, &port)) != 0)
789 sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__);
790 debug_f("tcpip-forward listen %s port %u",
791 fwd.listen_host, port);
793 fwd.listen_port = (int)port;
794 /* check permissions */
795 if (port > INT_MAX ||
796 (options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
797 !auth_opts->permit_port_forwarding_flag ||
798 options.disable_forwarding ||
799 (!want_reply && fwd.listen_port == 0) ||
800 (fwd.listen_port != 0 &&
801 !bind_permitted(fwd.listen_port, pw->pw_uid))) {
803 ssh_packet_send_debug(ssh, "Server has disabled port forwarding.");
805 /* Start listening on the port */
806 success = channel_setup_remote_fwd_listener(ssh, &fwd,
807 &allocated_listen_port, &options.fwd_opts);
809 if ((resp = sshbuf_new()) == NULL)
810 fatal_f("sshbuf_new");
811 if (allocated_listen_port != 0 &&
812 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
813 fatal_fr(r, "sshbuf_put_u32");
814 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
815 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
816 (r = sshpkt_get_u32(ssh, &port)) != 0)
817 sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__);
819 debug_f("cancel-tcpip-forward addr %s port %d",
820 fwd.listen_host, port);
821 if (port <= INT_MAX) {
822 fwd.listen_port = (int)port;
823 success = channel_cancel_rport_listener(ssh, &fwd);
825 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
826 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
827 sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__);
828 debug_f("streamlocal-forward listen path %s",
831 /* check permissions */
832 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
833 || !auth_opts->permit_port_forwarding_flag ||
834 options.disable_forwarding ||
835 (pw->pw_uid != 0 && !use_privsep)) {
837 ssh_packet_send_debug(ssh, "Server has disabled "
838 "streamlocal forwarding.");
840 /* Start listening on the socket */
841 success = channel_setup_remote_fwd_listener(ssh,
842 &fwd, NULL, &options.fwd_opts);
844 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
845 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
846 sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__);
847 debug_f("cancel-streamlocal-forward path %s",
850 success = channel_cancel_rport_listener(ssh, &fwd);
851 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
852 no_more_sessions = 1;
854 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
855 success = server_input_hostkeys_prove(ssh, &resp);
857 /* XXX sshpkt_get_end() */
859 if ((r = sshpkt_start(ssh, success ?
860 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 ||
861 (success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) ||
862 (r = sshpkt_send(ssh)) != 0 ||
863 (r = ssh_packet_write_wait(ssh)) != 0)
864 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
866 free(fwd.listen_host);
867 free(fwd.listen_path);
874 server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
879 u_char want_reply = 0;
882 if ((r = sshpkt_get_u32(ssh, &id)) != 0 ||
883 (r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
884 (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
885 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
887 debug("server_input_channel_req: channel %u request %s reply %d",
888 id, rtype, want_reply);
890 if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) {
891 ssh_packet_disconnect(ssh, "%s: unknown channel %d",
894 if (!strcmp(rtype, "eow@openssh.com")) {
895 if ((r = sshpkt_get_end(ssh)) != 0)
896 sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
897 chan_rcvd_eow(ssh, c);
898 } else if ((c->type == SSH_CHANNEL_LARVAL ||
899 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
900 success = session_input_channel_req(ssh, c, rtype);
901 if (want_reply && !(c->flags & CHAN_CLOSE_SENT)) {
902 if (!c->have_remote_id)
903 fatal_f("channel %d: no remote_id", c->self);
904 if ((r = sshpkt_start(ssh, success ?
905 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
906 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
907 (r = sshpkt_send(ssh)) != 0)
908 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
915 server_init_dispatch(struct ssh *ssh)
917 debug("server_init_dispatch");
918 ssh_dispatch_init(ssh, &dispatch_protocol_error);
919 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
920 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
921 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
922 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
923 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
924 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
925 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
926 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
927 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
928 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
930 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
931 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
932 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
933 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
935 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);