1 /* $OpenBSD: serverloop.c,v 1.191 2017/02/01 02:59:09 dtucker Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Server main loop for handling the interactive session.
7 *
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".
13 *
14 * SSH2 support by Markus Friedl.
15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
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.
25 *
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.
36 */
37
38 #include "includes.h"
39
40 #include <sys/types.h>
41 #include <sys/wait.h>
42 #include <sys/socket.h>
43 #ifdef HAVE_SYS_TIME_H
44 # include <sys/time.h>
45 #endif
46
47 #include <netinet/in.h>
48
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <pwd.h>
52 #include <signal.h>
53 #include <string.h>
54 #include <termios.h>
55 #include <unistd.h>
56 #include <stdarg.h>
57
58 #include "openbsd-compat/sys-queue.h"
59 #include "xmalloc.h"
60 #include "packet.h"
61 #include "buffer.h"
62 #include "log.h"
63 #include "misc.h"
64 #include "servconf.h"
65 #include "canohost.h"
66 #include "sshpty.h"
67 #include "channels.h"
68 #include "compat.h"
69 #include "ssh2.h"
70 #include "key.h"
71 #include "cipher.h"
72 #include "kex.h"
73 #include "hostfile.h"
74 #include "auth.h"
75 #include "session.h"
76 #include "dispatch.h"
77 #include "auth-options.h"
78 #include "serverloop.h"
79 #include "ssherr.h"
80
81 extern ServerOptions options;
82
83 /* XXX */
84 extern Authctxt *the_authctxt;
85 extern int use_privsep;
86
87 static int no_more_sessions = 0; /* Disallow further sessions. */
88
89 /*
90 * This SIGCHLD kludge is used to detect when the child exits. The server
91 * will exit after that, as soon as forwarded connections have terminated.
92 */
93
94 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */
95
96 /* Cleanup on signals (!use_privsep case only) */
97 static volatile sig_atomic_t received_sigterm = 0;
98
99 /* prototypes */
100 static void server_init_dispatch(void);
101
102 /*
103 * we write to this pipe if a SIGCHLD is caught in order to avoid
104 * the race between select() and child_terminated
105 */
106 static int notify_pipe[2];
107 static void
notify_setup(void)108 notify_setup(void)
109 {
110 if (pipe(notify_pipe) < 0) {
111 error("pipe(notify_pipe) failed %s", strerror(errno));
112 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
113 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
114 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
115 close(notify_pipe[0]);
116 close(notify_pipe[1]);
117 } else {
118 set_nonblock(notify_pipe[0]);
119 set_nonblock(notify_pipe[1]);
120 return;
121 }
122 notify_pipe[0] = -1; /* read end */
123 notify_pipe[1] = -1; /* write end */
124 }
125 static void
notify_parent(void)126 notify_parent(void)
127 {
128 if (notify_pipe[1] != -1)
129 (void)write(notify_pipe[1], "", 1);
130 }
131 static void
notify_prepare(fd_set * readset)132 notify_prepare(fd_set *readset)
133 {
134 if (notify_pipe[0] != -1)
135 FD_SET(notify_pipe[0], readset);
136 }
137 static void
notify_done(fd_set * readset)138 notify_done(fd_set *readset)
139 {
140 char c;
141
142 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
143 while (read(notify_pipe[0], &c, 1) != -1)
144 debug2("notify_done: reading");
145 }
146
147 /*ARGSUSED*/
148 static void
sigchld_handler(int sig)149 sigchld_handler(int sig)
150 {
151 int save_errno = errno;
152 child_terminated = 1;
153 #ifndef _UNICOS
154 mysignal(SIGCHLD, sigchld_handler);
155 #endif
156 notify_parent();
157 errno = save_errno;
158 }
159
160 /*ARGSUSED*/
161 static void
sigterm_handler(int sig)162 sigterm_handler(int sig)
163 {
164 received_sigterm = sig;
165 }
166
167 static void
client_alive_check(void)168 client_alive_check(void)
169 {
170 int channel_id;
171
172 /* timeout, check to see how many we have had */
173 if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
174 logit("Timeout, client not responding.");
175 cleanup_exit(255);
176 }
177
178 /*
179 * send a bogus global/channel request with "wantreply",
180 * we should get back a failure
181 */
182 if ((channel_id = channel_find_open()) == -1) {
183 packet_start(SSH2_MSG_GLOBAL_REQUEST);
184 packet_put_cstring("keepalive@openssh.com");
185 packet_put_char(1); /* boolean: want reply */
186 } else {
187 channel_request_start(channel_id, "keepalive@openssh.com", 1);
188 }
189 packet_send();
190 }
191
192 /*
193 * Sleep in select() until we can do something. This will initialize the
194 * select masks. Upon return, the masks will indicate which descriptors
195 * have data or can accept data. Optionally, a maximum time can be specified
196 * for the duration of the wait (0 = infinite).
197 */
198 static void
wait_until_can_do_something(int connection_in,int connection_out,fd_set ** readsetp,fd_set ** writesetp,int * maxfdp,u_int * nallocp,u_int64_t max_time_ms)199 wait_until_can_do_something(int connection_in, int connection_out,
200 fd_set **readsetp, fd_set **writesetp, int *maxfdp,
201 u_int *nallocp, u_int64_t max_time_ms)
202 {
203 struct timeval tv, *tvp;
204 int ret;
205 time_t minwait_secs = 0;
206 int client_alive_scheduled = 0;
207
208 /* Allocate and update select() masks for channel descriptors. */
209 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
210 &minwait_secs, 0);
211
212 /* XXX need proper deadline system for rekey/client alive */
213 if (minwait_secs != 0)
214 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000);
215
216 /*
217 * if using client_alive, set the max timeout accordingly,
218 * and indicate that this particular timeout was for client
219 * alive by setting the client_alive_scheduled flag.
220 *
221 * this could be randomized somewhat to make traffic
222 * analysis more difficult, but we're not doing it yet.
223 */
224 if (options.client_alive_interval) {
225 uint64_t keepalive_ms =
226 (uint64_t)options.client_alive_interval * 1000;
227
228 client_alive_scheduled = 1;
229 if (max_time_ms == 0 || max_time_ms > keepalive_ms)
230 max_time_ms = keepalive_ms;
231 }
232
233 #if 0
234 /* wrong: bad condition XXX */
235 if (channel_not_very_much_buffered_data())
236 #endif
237 FD_SET(connection_in, *readsetp);
238 notify_prepare(*readsetp);
239
240 /*
241 * If we have buffered packet data going to the client, mark that
242 * descriptor.
243 */
244 if (packet_have_data_to_write())
245 FD_SET(connection_out, *writesetp);
246
247 /*
248 * If child has terminated and there is enough buffer space to read
249 * from it, then read as much as is available and exit.
250 */
251 if (child_terminated && packet_not_very_much_data_to_write())
252 if (max_time_ms == 0 || client_alive_scheduled)
253 max_time_ms = 100;
254
255 if (max_time_ms == 0)
256 tvp = NULL;
257 else {
258 tv.tv_sec = max_time_ms / 1000;
259 tv.tv_usec = 1000 * (max_time_ms % 1000);
260 tvp = &tv;
261 }
262
263 /* Wait for something to happen, or the timeout to expire. */
264 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
265
266 if (ret == -1) {
267 memset(*readsetp, 0, *nallocp);
268 memset(*writesetp, 0, *nallocp);
269 if (errno != EINTR)
270 error("select: %.100s", strerror(errno));
271 } else if (ret == 0 && client_alive_scheduled)
272 client_alive_check();
273
274 notify_done(*readsetp);
275 }
276
277 /*
278 * Processes input from the client and the program. Input data is stored
279 * in buffers and processed later.
280 */
281 static int
process_input(fd_set * readset,int connection_in)282 process_input(fd_set *readset, int connection_in)
283 {
284 struct ssh *ssh = active_state; /* XXX */
285 int len;
286 char buf[16384];
287
288 /* Read and buffer any input data from the client. */
289 if (FD_ISSET(connection_in, readset)) {
290 len = read(connection_in, buf, sizeof(buf));
291 if (len == 0) {
292 verbose("Connection closed by %.100s port %d",
293 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
294 return -1;
295 } else if (len < 0) {
296 if (errno != EINTR && errno != EAGAIN &&
297 errno != EWOULDBLOCK) {
298 verbose("Read error from remote host "
299 "%.100s port %d: %.100s",
300 ssh_remote_ipaddr(ssh),
301 ssh_remote_port(ssh), strerror(errno));
302 cleanup_exit(255);
303 }
304 } else {
305 /* Buffer any received data. */
306 packet_process_incoming(buf, len);
307 }
308 }
309 return 0;
310 }
311
312 /*
313 * Sends data from internal buffers to client program stdin.
314 */
315 static void
process_output(fd_set * writeset,int connection_out)316 process_output(fd_set *writeset, int connection_out)
317 {
318 /* Send any buffered packet data to the client. */
319 if (FD_ISSET(connection_out, writeset))
320 packet_write_poll();
321 }
322
323 static void
process_buffered_input_packets(void)324 process_buffered_input_packets(void)
325 {
326 dispatch_run(DISPATCH_NONBLOCK, NULL, active_state);
327 }
328
329 static void
collect_children(void)330 collect_children(void)
331 {
332 pid_t pid;
333 sigset_t oset, nset;
334 int status;
335
336 /* block SIGCHLD while we check for dead children */
337 sigemptyset(&nset);
338 sigaddset(&nset, SIGCHLD);
339 sigprocmask(SIG_BLOCK, &nset, &oset);
340 if (child_terminated) {
341 debug("Received SIGCHLD.");
342 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
343 (pid < 0 && errno == EINTR))
344 if (pid > 0)
345 session_close_by_pid(pid, status);
346 child_terminated = 0;
347 }
348 sigprocmask(SIG_SETMASK, &oset, NULL);
349 }
350
351 void
server_loop2(Authctxt * authctxt)352 server_loop2(Authctxt *authctxt)
353 {
354 fd_set *readset = NULL, *writeset = NULL;
355 int max_fd;
356 u_int nalloc = 0, connection_in, connection_out;
357 u_int64_t rekey_timeout_ms = 0;
358
359 debug("Entering interactive session for SSH2.");
360
361 mysignal(SIGCHLD, sigchld_handler);
362 child_terminated = 0;
363 connection_in = packet_get_connection_in();
364 connection_out = packet_get_connection_out();
365
366 if (!use_privsep) {
367 signal(SIGTERM, sigterm_handler);
368 signal(SIGINT, sigterm_handler);
369 signal(SIGQUIT, sigterm_handler);
370 }
371
372 notify_setup();
373
374 max_fd = MAXIMUM(connection_in, connection_out);
375 max_fd = MAXIMUM(max_fd, notify_pipe[0]);
376
377 server_init_dispatch();
378
379 for (;;) {
380 process_buffered_input_packets();
381
382 if (!ssh_packet_is_rekeying(active_state) &&
383 packet_not_very_much_data_to_write())
384 channel_output_poll();
385 if (options.rekey_interval > 0 &&
386 !ssh_packet_is_rekeying(active_state))
387 rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
388 else
389 rekey_timeout_ms = 0;
390
391 wait_until_can_do_something(connection_in, connection_out,
392 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms);
393
394 if (received_sigterm) {
395 logit("Exiting on signal %d", (int)received_sigterm);
396 /* Clean up sessions, utmp, etc. */
397 cleanup_exit(255);
398 }
399
400 collect_children();
401 if (!ssh_packet_is_rekeying(active_state))
402 channel_after_select(readset, writeset);
403 if (process_input(readset, connection_in) < 0)
404 break;
405 process_output(writeset, connection_out);
406 }
407 collect_children();
408
409 free(readset);
410 free(writeset);
411
412 /* free all channels, no more reads and writes */
413 channel_free_all();
414
415 /* free remaining sessions, e.g. remove wtmp entries */
416 session_destroy_all(NULL);
417 }
418
419 static int
server_input_keep_alive(int type,u_int32_t seq,void * ctxt)420 server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
421 {
422 debug("Got %d/%u for keepalive", type, seq);
423 /*
424 * reset timeout, since we got a sane answer from the client.
425 * even if this was generated by something other than
426 * the bogus CHANNEL_REQUEST we send for keepalives.
427 */
428 packet_set_alive_timeouts(0);
429 return 0;
430 }
431
432 static Channel *
server_request_direct_tcpip(int * reason,const char ** errmsg)433 server_request_direct_tcpip(int *reason, const char **errmsg)
434 {
435 Channel *c = NULL;
436 char *target, *originator;
437 u_short target_port, originator_port;
438
439 target = packet_get_string(NULL);
440 target_port = packet_get_int();
441 originator = packet_get_string(NULL);
442 originator_port = packet_get_int();
443 packet_check_eom();
444
445 debug("server_request_direct_tcpip: originator %s port %d, target %s "
446 "port %d", originator, originator_port, target, target_port);
447
448 /* XXX fine grained permissions */
449 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
450 !no_port_forwarding_flag && !options.disable_forwarding) {
451 c = channel_connect_to_port(target, target_port,
452 "direct-tcpip", "direct-tcpip", reason, errmsg);
453 } else {
454 logit("refused local port forward: "
455 "originator %s port %d, target %s port %d",
456 originator, originator_port, target, target_port);
457 if (reason != NULL)
458 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
459 }
460
461 free(originator);
462 free(target);
463
464 return c;
465 }
466
467 static Channel *
server_request_direct_streamlocal(void)468 server_request_direct_streamlocal(void)
469 {
470 Channel *c = NULL;
471 char *target, *originator;
472 u_short originator_port;
473 struct passwd *pw = the_authctxt->pw;
474
475 if (pw == NULL || !the_authctxt->valid)
476 fatal("server_input_global_request: no/invalid user");
477
478 target = packet_get_string(NULL);
479 originator = packet_get_string(NULL);
480 originator_port = packet_get_int();
481 packet_check_eom();
482
483 debug("server_request_direct_streamlocal: originator %s port %d, target %s",
484 originator, originator_port, target);
485
486 /* XXX fine grained permissions */
487 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
488 !no_port_forwarding_flag && !options.disable_forwarding &&
489 (pw->pw_uid == 0 || use_privsep)) {
490 c = channel_connect_to_path(target,
491 "direct-streamlocal@openssh.com", "direct-streamlocal");
492 } else {
493 logit("refused streamlocal port forward: "
494 "originator %s port %d, target %s",
495 originator, originator_port, target);
496 }
497
498 free(originator);
499 free(target);
500
501 return c;
502 }
503
504 static Channel *
server_request_tun(void)505 server_request_tun(void)
506 {
507 Channel *c = NULL;
508 int mode, tun;
509 int sock;
510
511 mode = packet_get_int();
512 switch (mode) {
513 case SSH_TUNMODE_POINTOPOINT:
514 case SSH_TUNMODE_ETHERNET:
515 break;
516 default:
517 packet_send_debug("Unsupported tunnel device mode.");
518 return NULL;
519 }
520 if ((options.permit_tun & mode) == 0) {
521 packet_send_debug("Server has rejected tunnel device "
522 "forwarding");
523 return NULL;
524 }
525
526 tun = packet_get_int();
527 if (forced_tun_device != -1) {
528 if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
529 goto done;
530 tun = forced_tun_device;
531 }
532 sock = tun_open(tun, mode);
533 if (sock < 0)
534 goto done;
535 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
536 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
537 c->datagram = 1;
538 #if defined(SSH_TUN_FILTER)
539 if (mode == SSH_TUNMODE_POINTOPOINT)
540 channel_register_filter(c->self, sys_tun_infilter,
541 sys_tun_outfilter, NULL, NULL);
542 #endif
543
544 done:
545 if (c == NULL)
546 packet_send_debug("Failed to open the tunnel device.");
547 return c;
548 }
549
550 static Channel *
server_request_session(void)551 server_request_session(void)
552 {
553 Channel *c;
554
555 debug("input_session_request");
556 packet_check_eom();
557
558 if (no_more_sessions) {
559 packet_disconnect("Possible attack: attempt to open a session "
560 "after additional sessions disabled");
561 }
562
563 /*
564 * A server session has no fd to read or write until a
565 * CHANNEL_REQUEST for a shell is made, so we set the type to
566 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all
567 * CHANNEL_REQUEST messages is registered.
568 */
569 c = channel_new("session", SSH_CHANNEL_LARVAL,
570 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
571 0, "server-session", 1);
572 if (session_open(the_authctxt, c->self) != 1) {
573 debug("session open failed, free channel %d", c->self);
574 channel_free(c);
575 return NULL;
576 }
577 channel_register_cleanup(c->self, session_close_by_channel, 0);
578 return c;
579 }
580
581 static int
server_input_channel_open(int type,u_int32_t seq,void * ctxt)582 server_input_channel_open(int type, u_int32_t seq, void *ctxt)
583 {
584 Channel *c = NULL;
585 char *ctype;
586 const char *errmsg = NULL;
587 int rchan, reason = SSH2_OPEN_CONNECT_FAILED;
588 u_int rmaxpack, rwindow, len;
589
590 ctype = packet_get_string(&len);
591 rchan = packet_get_int();
592 rwindow = packet_get_int();
593 rmaxpack = packet_get_int();
594
595 debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
596 ctype, rchan, rwindow, rmaxpack);
597
598 if (strcmp(ctype, "session") == 0) {
599 c = server_request_session();
600 } else if (strcmp(ctype, "direct-tcpip") == 0) {
601 c = server_request_direct_tcpip(&reason, &errmsg);
602 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
603 c = server_request_direct_streamlocal();
604 } else if (strcmp(ctype, "tun@openssh.com") == 0) {
605 c = server_request_tun();
606 }
607 if (c != NULL) {
608 debug("server_input_channel_open: confirm %s", ctype);
609 c->remote_id = rchan;
610 c->remote_window = rwindow;
611 c->remote_maxpacket = rmaxpack;
612 if (c->type != SSH_CHANNEL_CONNECTING) {
613 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
614 packet_put_int(c->remote_id);
615 packet_put_int(c->self);
616 packet_put_int(c->local_window);
617 packet_put_int(c->local_maxpacket);
618 packet_send();
619 }
620 } else {
621 debug("server_input_channel_open: failure %s", ctype);
622 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
623 packet_put_int(rchan);
624 packet_put_int(reason);
625 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
626 packet_put_cstring(errmsg ? errmsg : "open failed");
627 packet_put_cstring("");
628 }
629 packet_send();
630 }
631 free(ctype);
632 return 0;
633 }
634
635 static int
server_input_hostkeys_prove(struct sshbuf ** respp)636 server_input_hostkeys_prove(struct sshbuf **respp)
637 {
638 struct ssh *ssh = active_state; /* XXX */
639 struct sshbuf *resp = NULL;
640 struct sshbuf *sigbuf = NULL;
641 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
642 int r, ndx, success = 0;
643 const u_char *blob;
644 u_char *sig = 0;
645 size_t blen, slen;
646
647 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
648 fatal("%s: sshbuf_new", __func__);
649
650 while (ssh_packet_remaining(ssh) > 0) {
651 sshkey_free(key);
652 key = NULL;
653 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
654 (r = sshkey_from_blob(blob, blen, &key)) != 0) {
655 error("%s: couldn't parse key: %s",
656 __func__, ssh_err(r));
657 goto out;
658 }
659 /*
660 * Better check that this is actually one of our hostkeys
661 * before attempting to sign anything with it.
662 */
663 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
664 error("%s: unknown host %s key",
665 __func__, sshkey_type(key));
666 goto out;
667 }
668 /*
669 * XXX refactor: make kex->sign just use an index rather
670 * than passing in public and private keys
671 */
672 if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
673 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
674 error("%s: can't retrieve hostkey %d", __func__, ndx);
675 goto out;
676 }
677 sshbuf_reset(sigbuf);
678 free(sig);
679 sig = NULL;
680 if ((r = sshbuf_put_cstring(sigbuf,
681 "hostkeys-prove-00@openssh.com")) != 0 ||
682 (r = sshbuf_put_string(sigbuf,
683 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
684 (r = sshkey_puts(key, sigbuf)) != 0 ||
685 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
686 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 ||
687 (r = sshbuf_put_string(resp, sig, slen)) != 0) {
688 error("%s: couldn't prepare signature: %s",
689 __func__, ssh_err(r));
690 goto out;
691 }
692 }
693 /* Success */
694 *respp = resp;
695 resp = NULL; /* don't free it */
696 success = 1;
697 out:
698 free(sig);
699 sshbuf_free(resp);
700 sshbuf_free(sigbuf);
701 sshkey_free(key);
702 return success;
703 }
704
705 static int
server_input_global_request(int type,u_int32_t seq,void * ctxt)706 server_input_global_request(int type, u_int32_t seq, void *ctxt)
707 {
708 char *rtype;
709 int want_reply;
710 int r, success = 0, allocated_listen_port = 0;
711 struct sshbuf *resp = NULL;
712 struct passwd *pw = the_authctxt->pw;
713
714 if (pw == NULL || !the_authctxt->valid)
715 fatal("server_input_global_request: no/invalid user");
716
717 rtype = packet_get_string(NULL);
718 want_reply = packet_get_char();
719 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
720
721 /* -R style forwarding */
722 if (strcmp(rtype, "tcpip-forward") == 0) {
723 struct Forward fwd;
724
725 memset(&fwd, 0, sizeof(fwd));
726 fwd.listen_host = packet_get_string(NULL);
727 fwd.listen_port = (u_short)packet_get_int();
728 debug("server_input_global_request: tcpip-forward listen %s port %d",
729 fwd.listen_host, fwd.listen_port);
730
731 /* check permissions */
732 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
733 no_port_forwarding_flag || options.disable_forwarding ||
734 (!want_reply && fwd.listen_port == 0) ||
735 (fwd.listen_port != 0 &&
736 !bind_permitted(fwd.listen_port, pw->pw_uid))) {
737 success = 0;
738 packet_send_debug("Server has disabled port forwarding.");
739 } else {
740 /* Start listening on the port */
741 success = channel_setup_remote_fwd_listener(&fwd,
742 &allocated_listen_port, &options.fwd_opts);
743 }
744 free(fwd.listen_host);
745 if ((resp = sshbuf_new()) == NULL)
746 fatal("%s: sshbuf_new", __func__);
747 if (allocated_listen_port != 0 &&
748 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
749 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
750 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
751 struct Forward fwd;
752
753 memset(&fwd, 0, sizeof(fwd));
754 fwd.listen_host = packet_get_string(NULL);
755 fwd.listen_port = (u_short)packet_get_int();
756 debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
757 fwd.listen_host, fwd.listen_port);
758
759 success = channel_cancel_rport_listener(&fwd);
760 free(fwd.listen_host);
761 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
762 struct Forward fwd;
763
764 memset(&fwd, 0, sizeof(fwd));
765 fwd.listen_path = packet_get_string(NULL);
766 debug("server_input_global_request: streamlocal-forward listen path %s",
767 fwd.listen_path);
768
769 /* check permissions */
770 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
771 || no_port_forwarding_flag || options.disable_forwarding ||
772 (pw->pw_uid != 0 && !use_privsep)) {
773 success = 0;
774 packet_send_debug("Server has disabled "
775 "streamlocal forwarding.");
776 } else {
777 /* Start listening on the socket */
778 success = channel_setup_remote_fwd_listener(
779 &fwd, NULL, &options.fwd_opts);
780 }
781 free(fwd.listen_path);
782 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
783 struct Forward fwd;
784
785 memset(&fwd, 0, sizeof(fwd));
786 fwd.listen_path = packet_get_string(NULL);
787 debug("%s: cancel-streamlocal-forward path %s", __func__,
788 fwd.listen_path);
789
790 success = channel_cancel_rport_listener(&fwd);
791 free(fwd.listen_path);
792 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
793 no_more_sessions = 1;
794 success = 1;
795 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
796 success = server_input_hostkeys_prove(&resp);
797 }
798 if (want_reply) {
799 packet_start(success ?
800 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
801 if (success && resp != NULL)
802 ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
803 sshbuf_len(resp));
804 packet_send();
805 packet_write_wait();
806 }
807 free(rtype);
808 sshbuf_free(resp);
809 return 0;
810 }
811
812 static int
server_input_channel_req(int type,u_int32_t seq,void * ctxt)813 server_input_channel_req(int type, u_int32_t seq, void *ctxt)
814 {
815 Channel *c;
816 int id, reply, success = 0;
817 char *rtype;
818
819 id = packet_get_int();
820 rtype = packet_get_string(NULL);
821 reply = packet_get_char();
822
823 debug("server_input_channel_req: channel %d request %s reply %d",
824 id, rtype, reply);
825
826 if ((c = channel_lookup(id)) == NULL)
827 packet_disconnect("server_input_channel_req: "
828 "unknown channel %d", id);
829 if (!strcmp(rtype, "eow@openssh.com")) {
830 packet_check_eom();
831 chan_rcvd_eow(c);
832 } else if ((c->type == SSH_CHANNEL_LARVAL ||
833 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
834 success = session_input_channel_req(c, rtype);
835 if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
836 packet_start(success ?
837 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
838 packet_put_int(c->remote_id);
839 packet_send();
840 }
841 free(rtype);
842 return 0;
843 }
844
845 static void
server_init_dispatch(void)846 server_init_dispatch(void)
847 {
848 debug("server_init_dispatch");
849 dispatch_init(&dispatch_protocol_error);
850 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
851 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
852 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
853 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
854 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
855 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
856 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
857 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
858 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
859 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
860 /* client_alive */
861 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
862 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
863 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
864 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
865 /* rekeying */
866 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
867 }
868