1 /* $OpenBSD: clientloop.c,v 1.403 2024/02/21 05:57:34 djm 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 * The main loop for the interactive session (client side).
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 *
15 * Copyright (c) 1999 Theo de Raadt. 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 * SSH2 support added by Markus Friedl.
39 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved.
40 *
41 * Redistribution and use in source and binary forms, with or without
42 * modification, are permitted provided that the following conditions
43 * are met:
44 * 1. Redistributions of source code must retain the above copyright
45 * notice, this list of conditions and the following disclaimer.
46 * 2. Redistributions in binary form must reproduce the above copyright
47 * notice, this list of conditions and the following disclaimer in the
48 * documentation and/or other materials provided with the distribution.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
51 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
52 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
53 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
54 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
55 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
56 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
57 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
58 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
59 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
60 */
61
62 #include "includes.h"
63
64 #include <sys/types.h>
65 #include <sys/ioctl.h>
66 #ifdef HAVE_SYS_STAT_H
67 # include <sys/stat.h>
68 #endif
69 #ifdef HAVE_SYS_TIME_H
70 # include <sys/time.h>
71 #endif
72 #include <sys/socket.h>
73
74 #include <ctype.h>
75 #include <errno.h>
76 #ifdef HAVE_PATHS_H
77 #include <paths.h>
78 #endif
79 #ifdef HAVE_POLL_H
80 #include <poll.h>
81 #endif
82 #include <signal.h>
83 #include <stdio.h>
84 #include <stdlib.h>
85 #include <string.h>
86 #include <stdarg.h>
87 #include <termios.h>
88 #include <pwd.h>
89 #include <unistd.h>
90 #include <limits.h>
91
92 #include "openbsd-compat/sys-queue.h"
93 #include "xmalloc.h"
94 #include "ssh.h"
95 #include "ssh2.h"
96 #include "packet.h"
97 #include "sshbuf.h"
98 #include "compat.h"
99 #include "channels.h"
100 #include "dispatch.h"
101 #include "sshkey.h"
102 #include "cipher.h"
103 #include "kex.h"
104 #include "myproposal.h"
105 #include "log.h"
106 #include "misc.h"
107 #include "readconf.h"
108 #include "clientloop.h"
109 #include "sshconnect.h"
110 #include "authfd.h"
111 #include "atomicio.h"
112 #include "sshpty.h"
113 #include "match.h"
114 #include "msg.h"
115 #include "ssherr.h"
116 #include "hostfile.h"
117
118 /* Permitted RSA signature algorithms for UpdateHostkeys proofs */
119 #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256"
120
121 /* Uncertainty (in percent) of keystroke timing intervals */
122 #define SSH_KEYSTROKE_TIMING_FUZZ 10
123
124 /* import options */
125 extern Options options;
126
127 /* Control socket */
128 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */
129
130 /*
131 * Name of the host we are connecting to. This is the name given on the
132 * command line, or the Hostname specified for the user-supplied name in a
133 * configuration file.
134 */
135 extern char *host;
136
137 /*
138 * If this field is not NULL, the ForwardAgent socket is this path and different
139 * instead of SSH_AUTH_SOCK.
140 */
141 extern char *forward_agent_sock_path;
142
143 /*
144 * Flag to indicate that we have received a window change signal which has
145 * not yet been processed. This will cause a message indicating the new
146 * window size to be sent to the server a little later. This is volatile
147 * because this is updated in a signal handler.
148 */
149 static volatile sig_atomic_t received_window_change_signal = 0;
150 static volatile sig_atomic_t received_signal = 0;
151
152 /* Time when backgrounded control master using ControlPersist should exit */
153 static time_t control_persist_exit_time = 0;
154
155 /* Common data for the client loop code. */
156 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
157 static int last_was_cr; /* Last character was a newline. */
158 static int exit_status; /* Used to store the command exit status. */
159 static struct sshbuf *stderr_buffer; /* Used for final exit message. */
160 static int connection_in; /* Connection to server (input). */
161 static int connection_out; /* Connection to server (output). */
162 static int need_rekeying; /* Set to non-zero if rekeying is requested. */
163 static int session_closed; /* In SSH2: login session closed. */
164 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */
165 static time_t server_alive_time; /* Time to do server_alive_check */
166 static int hostkeys_update_complete;
167 static int session_setup_complete;
168
169 static void client_init_dispatch(struct ssh *ssh);
170 int session_ident = -1;
171
172 /* Track escape per proto2 channel */
173 struct escape_filter_ctx {
174 int escape_pending;
175 int escape_char;
176 };
177
178 /* Context for channel confirmation replies */
179 struct channel_reply_ctx {
180 const char *request_type;
181 int id;
182 enum confirm_action action;
183 };
184
185 /* Global request success/failure callbacks */
186 /* XXX move to struct ssh? */
187 struct global_confirm {
188 TAILQ_ENTRY(global_confirm) entry;
189 global_confirm_cb *cb;
190 void *ctx;
191 int ref_count;
192 };
193 TAILQ_HEAD(global_confirms, global_confirm);
194 static struct global_confirms global_confirms =
195 TAILQ_HEAD_INITIALIZER(global_confirms);
196
197 void ssh_process_session2_setup(int, int, int, struct sshbuf *);
198 static void quit_message(const char *fmt, ...)
199 __attribute__((__format__ (printf, 1, 2)));
200
201 static void
quit_message(const char * fmt,...)202 quit_message(const char *fmt, ...)
203 {
204 char *msg;
205 va_list args;
206 int r;
207
208 va_start(args, fmt);
209 xvasprintf(&msg, fmt, args);
210 va_end(args);
211
212 if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0)
213 fatal_fr(r, "sshbuf_putf");
214 free(msg);
215 quit_pending = 1;
216 }
217
218 /*
219 * Signal handler for the window change signal (SIGWINCH). This just sets a
220 * flag indicating that the window has changed.
221 */
222 static void
window_change_handler(int sig)223 window_change_handler(int sig)
224 {
225 received_window_change_signal = 1;
226 }
227
228 /*
229 * Signal handler for signals that cause the program to terminate. These
230 * signals must be trapped to restore terminal modes.
231 */
232 static void
signal_handler(int sig)233 signal_handler(int sig)
234 {
235 received_signal = sig;
236 quit_pending = 1;
237 }
238
239 /*
240 * Sets control_persist_exit_time to the absolute time when the
241 * backgrounded control master should exit due to expiry of the
242 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded
243 * control master process, or if there is no ControlPersist timeout.
244 */
245 static void
set_control_persist_exit_time(struct ssh * ssh)246 set_control_persist_exit_time(struct ssh *ssh)
247 {
248 if (muxserver_sock == -1 || !options.control_persist
249 || options.control_persist_timeout == 0) {
250 /* not using a ControlPersist timeout */
251 control_persist_exit_time = 0;
252 } else if (channel_still_open(ssh)) {
253 /* some client connections are still open */
254 if (control_persist_exit_time > 0)
255 debug2_f("cancel scheduled exit");
256 control_persist_exit_time = 0;
257 } else if (control_persist_exit_time <= 0) {
258 /* a client connection has recently closed */
259 control_persist_exit_time = monotime() +
260 (time_t)options.control_persist_timeout;
261 debug2_f("schedule exit in %d seconds",
262 options.control_persist_timeout);
263 }
264 /* else we are already counting down to the timeout */
265 }
266
267 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
268 static int
client_x11_display_valid(const char * display)269 client_x11_display_valid(const char *display)
270 {
271 size_t i, dlen;
272
273 if (display == NULL)
274 return 0;
275
276 dlen = strlen(display);
277 for (i = 0; i < dlen; i++) {
278 if (!isalnum((u_char)display[i]) &&
279 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
280 debug("Invalid character '%c' in DISPLAY", display[i]);
281 return 0;
282 }
283 }
284 return 1;
285 }
286
287 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
288 #define X11_TIMEOUT_SLACK 60
289 int
client_x11_get_proto(struct ssh * ssh,const char * display,const char * xauth_path,u_int trusted,u_int timeout,char ** _proto,char ** _data)290 client_x11_get_proto(struct ssh *ssh, const char *display,
291 const char *xauth_path, u_int trusted, u_int timeout,
292 char **_proto, char **_data)
293 {
294 char *cmd, line[512], xdisplay[512];
295 char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
296 static char proto[512], data[512];
297 FILE *f;
298 int got_data = 0, generated = 0, do_unlink = 0, r;
299 struct stat st;
300 u_int now, x11_timeout_real;
301
302 *_proto = proto;
303 *_data = data;
304 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';
305
306 if (!client_x11_display_valid(display)) {
307 if (display != NULL)
308 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
309 display);
310 return -1;
311 }
312 if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
313 debug("No xauth program.");
314 xauth_path = NULL;
315 }
316
317 if (xauth_path != NULL) {
318 /*
319 * Handle FamilyLocal case where $DISPLAY does
320 * not match an authorization entry. For this we
321 * just try "xauth list unix:displaynum.screennum".
322 * XXX: "localhost" match to determine FamilyLocal
323 * is not perfect.
324 */
325 if (strncmp(display, "localhost:", 10) == 0) {
326 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
327 display + 10)) < 0 ||
328 (size_t)r >= sizeof(xdisplay)) {
329 error_f("display name too long");
330 return -1;
331 }
332 display = xdisplay;
333 }
334 if (trusted == 0) {
335 /*
336 * Generate an untrusted X11 auth cookie.
337 *
338 * The authentication cookie should briefly outlive
339 * ssh's willingness to forward X11 connections to
340 * avoid nasty fail-open behaviour in the X server.
341 */
342 mktemp_proto(xauthdir, sizeof(xauthdir));
343 if (mkdtemp(xauthdir) == NULL) {
344 error_f("mkdtemp: %s", strerror(errno));
345 return -1;
346 }
347 do_unlink = 1;
348 if ((r = snprintf(xauthfile, sizeof(xauthfile),
349 "%s/xauthfile", xauthdir)) < 0 ||
350 (size_t)r >= sizeof(xauthfile)) {
351 error_f("xauthfile path too long");
352 rmdir(xauthdir);
353 return -1;
354 }
355
356 if (timeout == 0) {
357 /* auth doesn't time out */
358 xasprintf(&cmd, "%s -f %s generate %s %s "
359 "untrusted 2>%s",
360 xauth_path, xauthfile, display,
361 SSH_X11_PROTO, _PATH_DEVNULL);
362 } else {
363 /* Add some slack to requested expiry */
364 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK)
365 x11_timeout_real = timeout +
366 X11_TIMEOUT_SLACK;
367 else {
368 /* Don't overflow on long timeouts */
369 x11_timeout_real = UINT_MAX;
370 }
371 xasprintf(&cmd, "%s -f %s generate %s %s "
372 "untrusted timeout %u 2>%s",
373 xauth_path, xauthfile, display,
374 SSH_X11_PROTO, x11_timeout_real,
375 _PATH_DEVNULL);
376 }
377 debug2_f("xauth command: %s", cmd);
378
379 if (timeout != 0 && x11_refuse_time == 0) {
380 now = monotime() + 1;
381 if (SSH_TIME_T_MAX - timeout < now)
382 x11_refuse_time = SSH_TIME_T_MAX;
383 else
384 x11_refuse_time = now + timeout;
385 channel_set_x11_refuse_time(ssh,
386 x11_refuse_time);
387 }
388 if (system(cmd) == 0)
389 generated = 1;
390 free(cmd);
391 }
392
393 /*
394 * When in untrusted mode, we read the cookie only if it was
395 * successfully generated as an untrusted one in the step
396 * above.
397 */
398 if (trusted || generated) {
399 xasprintf(&cmd,
400 "%s %s%s list %s 2>" _PATH_DEVNULL,
401 xauth_path,
402 generated ? "-f " : "" ,
403 generated ? xauthfile : "",
404 display);
405 debug2("x11_get_proto: %s", cmd);
406 f = popen(cmd, "r");
407 if (f && fgets(line, sizeof(line), f) &&
408 sscanf(line, "%*s %511s %511s", proto, data) == 2)
409 got_data = 1;
410 if (f)
411 pclose(f);
412 free(cmd);
413 }
414 }
415
416 if (do_unlink) {
417 unlink(xauthfile);
418 rmdir(xauthdir);
419 }
420
421 /* Don't fall back to fake X11 data for untrusted forwarding */
422 if (!trusted && !got_data) {
423 error("Warning: untrusted X11 forwarding setup failed: "
424 "xauth key data not generated");
425 return -1;
426 }
427
428 /*
429 * If we didn't get authentication data, just make up some
430 * data. The forwarding code will check the validity of the
431 * response anyway, and substitute this data. The X11
432 * server, however, will ignore this fake data and use
433 * whatever authentication mechanisms it was using otherwise
434 * for the local connection.
435 */
436 if (!got_data) {
437 u_int8_t rnd[16];
438 u_int i;
439
440 logit("Warning: No xauth data; "
441 "using fake authentication data for X11 forwarding.");
442 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
443 arc4random_buf(rnd, sizeof(rnd));
444 for (i = 0; i < sizeof(rnd); i++) {
445 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
446 rnd[i]);
447 }
448 }
449
450 return 0;
451 }
452
453 /*
454 * Checks if the client window has changed, and sends a packet about it to
455 * the server if so. The actual change is detected elsewhere (by a software
456 * interrupt on Unix); this just checks the flag and sends a message if
457 * appropriate.
458 */
459
460 static void
client_check_window_change(struct ssh * ssh)461 client_check_window_change(struct ssh *ssh)
462 {
463 if (!received_window_change_signal)
464 return;
465 received_window_change_signal = 0;
466 debug2_f("changed");
467 channel_send_window_changes(ssh);
468 }
469
470 static int
client_global_request_reply(int type,u_int32_t seq,struct ssh * ssh)471 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
472 {
473 struct global_confirm *gc;
474
475 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
476 return 0;
477 if (gc->cb != NULL)
478 gc->cb(ssh, type, seq, gc->ctx);
479 if (--gc->ref_count <= 0) {
480 TAILQ_REMOVE(&global_confirms, gc, entry);
481 freezero(gc, sizeof(*gc));
482 }
483
484 ssh_packet_set_alive_timeouts(ssh, 0);
485 return 0;
486 }
487
488 static void
schedule_server_alive_check(void)489 schedule_server_alive_check(void)
490 {
491 if (options.server_alive_interval > 0)
492 server_alive_time = monotime() + options.server_alive_interval;
493 }
494
495 static void
server_alive_check(struct ssh * ssh)496 server_alive_check(struct ssh *ssh)
497 {
498 int r;
499
500 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) {
501 logit("Timeout, server %s not responding.", host);
502 cleanup_exit(255);
503 }
504 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
505 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 ||
506 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */
507 (r = sshpkt_send(ssh)) != 0)
508 fatal_fr(r, "send packet");
509 /* Insert an empty placeholder to maintain ordering */
510 client_register_global_confirm(NULL, NULL);
511 schedule_server_alive_check();
512 }
513
514 /* Try to send a dummy keystroke */
515 static int
send_chaff(struct ssh * ssh)516 send_chaff(struct ssh *ssh)
517 {
518 int r;
519
520 if (ssh->kex == NULL || (ssh->kex->flags & KEX_HAS_PING) == 0)
521 return 0;
522 /* XXX probabilistically send chaff? */
523 /*
524 * a SSH2_MSG_CHANNEL_DATA payload is 9 bytes:
525 * 4 bytes channel ID + 4 bytes string length + 1 byte string data
526 * simulate that here.
527 */
528 if ((r = sshpkt_start(ssh, SSH2_MSG_PING)) != 0 ||
529 (r = sshpkt_put_cstring(ssh, "PING!")) != 0 ||
530 (r = sshpkt_send(ssh)) != 0)
531 fatal_fr(r, "send packet");
532 return 1;
533 }
534
535 /* Sets the next interval to send a keystroke or chaff packet */
536 static void
set_next_interval(const struct timespec * now,struct timespec * next_interval,u_int interval_ms,int starting)537 set_next_interval(const struct timespec *now, struct timespec *next_interval,
538 u_int interval_ms, int starting)
539 {
540 struct timespec tmp;
541 long long interval_ns, fuzz_ns;
542 static long long rate_fuzz;
543
544 interval_ns = interval_ms * (1000LL * 1000);
545 fuzz_ns = (interval_ns * SSH_KEYSTROKE_TIMING_FUZZ) / 100;
546 /* Center fuzz around requested interval */
547 if (fuzz_ns > INT_MAX)
548 fuzz_ns = INT_MAX;
549 if (fuzz_ns > interval_ns) {
550 /* Shouldn't happen */
551 fatal_f("internal error: fuzz %u%% %lldns > interval %lldns",
552 SSH_KEYSTROKE_TIMING_FUZZ, fuzz_ns, interval_ns);
553 }
554 /*
555 * Randomise the keystroke/chaff intervals in two ways:
556 * 1. Each interval has some random jitter applied to make the
557 * interval-to-interval time unpredictable.
558 * 2. The overall interval rate is also randomly perturbed for each
559 * chaffing session to make the average rate unpredictable.
560 */
561 if (starting)
562 rate_fuzz = arc4random_uniform(fuzz_ns);
563 interval_ns -= fuzz_ns;
564 interval_ns += arc4random_uniform(fuzz_ns) + rate_fuzz;
565
566 tmp.tv_sec = interval_ns / (1000 * 1000 * 1000);
567 tmp.tv_nsec = interval_ns % (1000 * 1000 * 1000);
568
569 timespecadd(now, &tmp, next_interval);
570 }
571
572 /*
573 * Performs keystroke timing obfuscation. Returns non-zero if the
574 * output fd should be polled.
575 */
576 static int
obfuscate_keystroke_timing(struct ssh * ssh,struct timespec * timeout,int channel_did_enqueue)577 obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout,
578 int channel_did_enqueue)
579 {
580 static int active;
581 static struct timespec next_interval, chaff_until;
582 struct timespec now, tmp;
583 int just_started = 0, had_keystroke = 0;
584 static unsigned long long nchaff;
585 char *stop_reason = NULL;
586 long long n;
587
588 monotime_ts(&now);
589
590 if (options.obscure_keystroke_timing_interval <= 0)
591 return 1; /* disabled in config */
592
593 if (!channel_tty_open(ssh) || quit_pending) {
594 /* Stop if no channels left of we're waiting for one to close */
595 stop_reason = "no active channels";
596 } else if (ssh_packet_is_rekeying(ssh)) {
597 /* Stop if we're rekeying */
598 stop_reason = "rekeying started";
599 } else if (!ssh_packet_interactive_data_to_write(ssh) &&
600 ssh_packet_have_data_to_write(ssh)) {
601 /* Stop if the output buffer has more than a few keystrokes */
602 stop_reason = "output buffer filling";
603 } else if (active && channel_did_enqueue &&
604 ssh_packet_have_data_to_write(ssh)) {
605 /* Still in active mode and have a keystroke queued. */
606 had_keystroke = 1;
607 } else if (active) {
608 if (timespeccmp(&now, &chaff_until, >=)) {
609 /* Stop if there have been no keystrokes for a while */
610 stop_reason = "chaff time expired";
611 } else if (timespeccmp(&now, &next_interval, >=)) {
612 /* Otherwise if we were due to send, then send chaff */
613 if (send_chaff(ssh))
614 nchaff++;
615 }
616 }
617
618 if (stop_reason != NULL) {
619 if (active) {
620 debug3_f("stopping: %s (%llu chaff packets sent)",
621 stop_reason, nchaff);
622 active = 0;
623 }
624 return 1;
625 }
626
627 /*
628 * If we're in interactive mode, and only have a small amount
629 * of outbound data, then we assume that the user is typing
630 * interactively. In this case, start quantising outbound packets to
631 * fixed time intervals to hide inter-keystroke timing.
632 */
633 if (!active && ssh_packet_interactive_data_to_write(ssh) &&
634 channel_did_enqueue && ssh_packet_have_data_to_write(ssh)) {
635 debug3_f("starting: interval ~%dms",
636 options.obscure_keystroke_timing_interval);
637 just_started = had_keystroke = active = 1;
638 nchaff = 0;
639 set_next_interval(&now, &next_interval,
640 options.obscure_keystroke_timing_interval, 1);
641 }
642
643 /* Don't hold off if obfuscation inactive */
644 if (!active)
645 return 1;
646
647 if (had_keystroke) {
648 /*
649 * Arrange to send chaff packets for a random interval after
650 * the last keystroke was sent.
651 */
652 ms_to_timespec(&tmp, SSH_KEYSTROKE_CHAFF_MIN_MS +
653 arc4random_uniform(SSH_KEYSTROKE_CHAFF_RNG_MS));
654 timespecadd(&now, &tmp, &chaff_until);
655 }
656
657 ptimeout_deadline_monotime_tsp(timeout, &next_interval);
658
659 if (just_started)
660 return 1;
661
662 /* Don't arm output fd for poll until the timing interval has elapsed */
663 if (timespeccmp(&now, &next_interval, <))
664 return 0;
665
666 /* Calculate number of intervals missed since the last check */
667 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000;
668 n += now.tv_nsec - next_interval.tv_nsec;
669 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000;
670 n = (n < 0) ? 1 : n + 1;
671
672 /* Advance to the next interval */
673 set_next_interval(&now, &next_interval,
674 options.obscure_keystroke_timing_interval * n, 0);
675 return 1;
676 }
677
678 /*
679 * Waits until the client can do something (some data becomes available on
680 * one of the file descriptors).
681 */
682 static void
client_wait_until_can_do_something(struct ssh * ssh,struct pollfd ** pfdp,u_int * npfd_allocp,u_int * npfd_activep,int channel_did_enqueue,sigset_t * sigsetp,int * conn_in_readyp,int * conn_out_readyp)683 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp,
684 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue,
685 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp)
686 {
687 struct timespec timeout;
688 int ret, oready;
689 u_int p;
690
691 *conn_in_readyp = *conn_out_readyp = 0;
692
693 /* Prepare channel poll. First two pollfd entries are reserved */
694 ptimeout_init(&timeout);
695 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout);
696 if (*npfd_activep < 2)
697 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
698
699 /* channel_prepare_poll could have closed the last channel */
700 if (session_closed && !channel_still_open(ssh) &&
701 !ssh_packet_have_data_to_write(ssh)) {
702 /* clear events since we did not call poll() */
703 for (p = 0; p < *npfd_activep; p++)
704 (*pfdp)[p].revents = 0;
705 return;
706 }
707
708 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue);
709
710 /* Monitor server connection on reserved pollfd entries */
711 (*pfdp)[0].fd = connection_in;
712 (*pfdp)[0].events = POLLIN;
713 (*pfdp)[1].fd = connection_out;
714 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ?
715 POLLOUT : 0;
716
717 /*
718 * Wait for something to happen. This will suspend the process until
719 * some polled descriptor can be read, written, or has some other
720 * event pending, or a timeout expires.
721 */
722 set_control_persist_exit_time(ssh);
723 if (control_persist_exit_time > 0)
724 ptimeout_deadline_monotime(&timeout, control_persist_exit_time);
725 if (options.server_alive_interval > 0)
726 ptimeout_deadline_monotime(&timeout, server_alive_time);
727 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) {
728 ptimeout_deadline_sec(&timeout,
729 ssh_packet_get_rekey_timeout(ssh));
730 }
731
732 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp);
733
734 if (ret == -1) {
735 /*
736 * We have to clear the events because we return.
737 * We have to return, because the mainloop checks for the flags
738 * set by the signal handlers.
739 */
740 for (p = 0; p < *npfd_activep; p++)
741 (*pfdp)[p].revents = 0;
742 if (errno == EINTR)
743 return;
744 /* Note: we might still have data in the buffers. */
745 quit_message("poll: %s", strerror(errno));
746 return;
747 }
748
749 *conn_in_readyp = (*pfdp)[0].revents != 0;
750 *conn_out_readyp = (*pfdp)[1].revents != 0;
751
752 if (options.server_alive_interval > 0 && !*conn_in_readyp &&
753 monotime() >= server_alive_time) {
754 /*
755 * ServerAlive check is needed. We can't rely on the poll
756 * timing out since traffic on the client side such as port
757 * forwards can keep waking it up.
758 */
759 server_alive_check(ssh);
760 }
761 }
762
763 static void
client_suspend_self(struct sshbuf * bin,struct sshbuf * bout,struct sshbuf * berr)764 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr)
765 {
766 /* Flush stdout and stderr buffers. */
767 if (sshbuf_len(bout) > 0)
768 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout),
769 sshbuf_len(bout));
770 if (sshbuf_len(berr) > 0)
771 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr),
772 sshbuf_len(berr));
773
774 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
775
776 sshbuf_reset(bin);
777 sshbuf_reset(bout);
778 sshbuf_reset(berr);
779
780 /* Send the suspend signal to the program itself. */
781 kill(getpid(), SIGTSTP);
782
783 /* Reset window sizes in case they have changed */
784 received_window_change_signal = 1;
785
786 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
787 }
788
789 static void
client_process_net_input(struct ssh * ssh)790 client_process_net_input(struct ssh *ssh)
791 {
792 int r;
793
794 /*
795 * Read input from the server, and add any such data to the buffer of
796 * the packet subsystem.
797 */
798 schedule_server_alive_check();
799 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
800 return; /* success */
801 if (r == SSH_ERR_SYSTEM_ERROR) {
802 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
803 return;
804 if (errno == EPIPE) {
805 quit_message("Connection to %s closed by remote host.",
806 host);
807 return;
808 }
809 }
810 quit_message("Read from remote host %s: %s", host, ssh_err(r));
811 }
812
813 static void
client_status_confirm(struct ssh * ssh,int type,Channel * c,void * ctx)814 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx)
815 {
816 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
817 char errmsg[256];
818 int r, tochan;
819
820 /*
821 * If a TTY was explicitly requested, then a failure to allocate
822 * one is fatal.
823 */
824 if (cr->action == CONFIRM_TTY &&
825 (options.request_tty == REQUEST_TTY_FORCE ||
826 options.request_tty == REQUEST_TTY_YES))
827 cr->action = CONFIRM_CLOSE;
828
829 /* XXX suppress on mux _client_ quietmode */
830 tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
831 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
832
833 if (type == SSH2_MSG_CHANNEL_SUCCESS) {
834 debug2("%s request accepted on channel %d",
835 cr->request_type, c->self);
836 } else if (type == SSH2_MSG_CHANNEL_FAILURE) {
837 if (tochan) {
838 snprintf(errmsg, sizeof(errmsg),
839 "%s request failed\r\n", cr->request_type);
840 } else {
841 snprintf(errmsg, sizeof(errmsg),
842 "%s request failed on channel %d",
843 cr->request_type, c->self);
844 }
845 /* If error occurred on primary session channel, then exit */
846 if (cr->action == CONFIRM_CLOSE && c->self == session_ident)
847 fatal("%s", errmsg);
848 /*
849 * If error occurred on mux client, append to
850 * their stderr.
851 */
852 if (tochan) {
853 debug3_f("channel %d: mux request: %s", c->self,
854 cr->request_type);
855 if ((r = sshbuf_put(c->extended, errmsg,
856 strlen(errmsg))) != 0)
857 fatal_fr(r, "sshbuf_put");
858 } else
859 error("%s", errmsg);
860 if (cr->action == CONFIRM_TTY) {
861 /*
862 * If a TTY allocation error occurred, then arrange
863 * for the correct TTY to leave raw mode.
864 */
865 if (c->self == session_ident)
866 leave_raw_mode(0);
867 else
868 mux_tty_alloc_failed(ssh, c);
869 } else if (cr->action == CONFIRM_CLOSE) {
870 chan_read_failed(ssh, c);
871 chan_write_failed(ssh, c);
872 }
873 }
874 free(cr);
875 }
876
877 static void
client_abandon_status_confirm(struct ssh * ssh,Channel * c,void * ctx)878 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx)
879 {
880 free(ctx);
881 }
882
883 void
client_expect_confirm(struct ssh * ssh,int id,const char * request,enum confirm_action action)884 client_expect_confirm(struct ssh *ssh, int id, const char *request,
885 enum confirm_action action)
886 {
887 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));
888
889 cr->request_type = request;
890 cr->action = action;
891
892 channel_register_status_confirm(ssh, id, client_status_confirm,
893 client_abandon_status_confirm, cr);
894 }
895
896 void
client_register_global_confirm(global_confirm_cb * cb,void * ctx)897 client_register_global_confirm(global_confirm_cb *cb, void *ctx)
898 {
899 struct global_confirm *gc, *last_gc;
900
901 /* Coalesce identical callbacks */
902 last_gc = TAILQ_LAST(&global_confirms, global_confirms);
903 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) {
904 if (++last_gc->ref_count >= INT_MAX)
905 fatal_f("last_gc->ref_count = %d",
906 last_gc->ref_count);
907 return;
908 }
909
910 gc = xcalloc(1, sizeof(*gc));
911 gc->cb = cb;
912 gc->ctx = ctx;
913 gc->ref_count = 1;
914 TAILQ_INSERT_TAIL(&global_confirms, gc, entry);
915 }
916
917 /*
918 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com
919 * hostkey update request.
920 */
921 static int
can_update_hostkeys(void)922 can_update_hostkeys(void)
923 {
924 if (hostkeys_update_complete)
925 return 0;
926 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
927 options.batch_mode)
928 return 0; /* won't ask in batchmode, so don't even try */
929 if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
930 return 0;
931 return 1;
932 }
933
934 static void
client_repledge(void)935 client_repledge(void)
936 {
937 debug3_f("enter");
938
939 /* Might be able to tighten pledge now that session is established */
940 if (options.control_master || options.control_path != NULL ||
941 options.forward_x11 || options.fork_after_authentication ||
942 can_update_hostkeys() ||
943 (session_ident != -1 && !session_setup_complete)) {
944 /* Can't tighten */
945 return;
946 }
947 /*
948 * LocalCommand and UpdateHostkeys have finished, so can get rid of
949 * filesystem.
950 *
951 * XXX protocol allows a server can to change hostkeys during the
952 * connection at rekey time that could trigger a hostkeys update
953 * but AFAIK no implementations support this. Could improve by
954 * forcing known_hosts to be read-only or via unveil(2).
955 */
956 if (options.num_local_forwards != 0 ||
957 options.num_remote_forwards != 0 ||
958 options.num_permitted_remote_opens != 0 ||
959 options.enable_escape_commandline != 0) {
960 /* rfwd needs inet */
961 debug("pledge: network");
962 if (pledge("stdio unix inet dns proc tty", NULL) == -1)
963 fatal_f("pledge(): %s", strerror(errno));
964 } else if (options.forward_agent != 0) {
965 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */
966 debug("pledge: agent");
967 if (pledge("stdio unix proc tty", NULL) == -1)
968 fatal_f("pledge(): %s", strerror(errno));
969 } else {
970 debug("pledge: fork");
971 if (pledge("stdio proc tty", NULL) == -1)
972 fatal_f("pledge(): %s", strerror(errno));
973 }
974 /* XXX further things to do:
975 *
976 * - might be able to get rid of proc if we kill ~^Z
977 * - ssh -N (no session)
978 * - stdio forwarding
979 * - sessions without tty
980 */
981 }
982
983 static void
process_cmdline(struct ssh * ssh)984 process_cmdline(struct ssh *ssh)
985 {
986 void (*handler)(int);
987 char *s, *cmd;
988 int ok, delete = 0, local = 0, remote = 0, dynamic = 0;
989 struct Forward fwd;
990
991 memset(&fwd, 0, sizeof(fwd));
992
993 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
994 handler = ssh_signal(SIGINT, SIG_IGN);
995 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
996 if (s == NULL)
997 goto out;
998 while (isspace((u_char)*s))
999 s++;
1000 if (*s == '-')
1001 s++; /* Skip cmdline '-', if any */
1002 if (*s == '\0')
1003 goto out;
1004
1005 if (*s == 'h' || *s == 'H' || *s == '?') {
1006 logit("Commands:");
1007 logit(" -L[bind_address:]port:host:hostport "
1008 "Request local forward");
1009 logit(" -R[bind_address:]port:host:hostport "
1010 "Request remote forward");
1011 logit(" -D[bind_address:]port "
1012 "Request dynamic forward");
1013 logit(" -KL[bind_address:]port "
1014 "Cancel local forward");
1015 logit(" -KR[bind_address:]port "
1016 "Cancel remote forward");
1017 logit(" -KD[bind_address:]port "
1018 "Cancel dynamic forward");
1019 if (!options.permit_local_command)
1020 goto out;
1021 logit(" !args "
1022 "Execute local command");
1023 goto out;
1024 }
1025
1026 if (*s == '!' && options.permit_local_command) {
1027 s++;
1028 ssh_local_cmd(s);
1029 goto out;
1030 }
1031
1032 if (*s == 'K') {
1033 delete = 1;
1034 s++;
1035 }
1036 if (*s == 'L')
1037 local = 1;
1038 else if (*s == 'R')
1039 remote = 1;
1040 else if (*s == 'D')
1041 dynamic = 1;
1042 else {
1043 logit("Invalid command.");
1044 goto out;
1045 }
1046
1047 while (isspace((u_char)*++s))
1048 ;
1049
1050 /* XXX update list of forwards in options */
1051 if (delete) {
1052 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */
1053 if (!parse_forward(&fwd, s, 1, 0)) {
1054 logit("Bad forwarding close specification.");
1055 goto out;
1056 }
1057 if (remote)
1058 ok = channel_request_rforward_cancel(ssh, &fwd) == 0;
1059 else if (dynamic)
1060 ok = channel_cancel_lport_listener(ssh, &fwd,
1061 0, &options.fwd_opts) > 0;
1062 else
1063 ok = channel_cancel_lport_listener(ssh, &fwd,
1064 CHANNEL_CANCEL_PORT_STATIC,
1065 &options.fwd_opts) > 0;
1066 if (!ok) {
1067 logit("Unknown port forwarding.");
1068 goto out;
1069 }
1070 logit("Canceled forwarding.");
1071 } else {
1072 /* -R specs can be both dynamic or not, so check both. */
1073 if (remote) {
1074 if (!parse_forward(&fwd, s, 0, remote) &&
1075 !parse_forward(&fwd, s, 1, remote)) {
1076 logit("Bad remote forwarding specification.");
1077 goto out;
1078 }
1079 } else if (!parse_forward(&fwd, s, dynamic, remote)) {
1080 logit("Bad local forwarding specification.");
1081 goto out;
1082 }
1083 if (local || dynamic) {
1084 if (!channel_setup_local_fwd_listener(ssh, &fwd,
1085 &options.fwd_opts)) {
1086 logit("Port forwarding failed.");
1087 goto out;
1088 }
1089 } else {
1090 if (channel_request_remote_forwarding(ssh, &fwd) < 0) {
1091 logit("Port forwarding failed.");
1092 goto out;
1093 }
1094 }
1095 logit("Forwarding port.");
1096 }
1097
1098 out:
1099 ssh_signal(SIGINT, handler);
1100 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1101 free(cmd);
1102 free(fwd.listen_host);
1103 free(fwd.listen_path);
1104 free(fwd.connect_host);
1105 free(fwd.connect_path);
1106 }
1107
1108 /* reasons to suppress output of an escape command in help output */
1109 #define SUPPRESS_NEVER 0 /* never suppress, always show */
1110 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */
1111 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */
1112 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */
1113 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/
1114 struct escape_help_text {
1115 const char *cmd;
1116 const char *text;
1117 unsigned int flags;
1118 };
1119 static struct escape_help_text esc_txt[] = {
1120 {".", "terminate session", SUPPRESS_MUXMASTER},
1121 {".", "terminate connection (and any multiplexed sessions)",
1122 SUPPRESS_MUXCLIENT},
1123 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER},
1124 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE},
1125 {"R", "request rekey", SUPPRESS_NEVER},
1126 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT},
1127 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT},
1128 {"#", "list forwarded connections", SUPPRESS_NEVER},
1129 {"&", "background ssh (when waiting for connections to terminate)",
1130 SUPPRESS_MUXCLIENT},
1131 {"?", "this message", SUPPRESS_NEVER},
1132 };
1133
1134 static void
print_escape_help(struct sshbuf * b,int escape_char,int mux_client,int using_stderr)1135 print_escape_help(struct sshbuf *b, int escape_char, int mux_client,
1136 int using_stderr)
1137 {
1138 unsigned int i, suppress_flags;
1139 int r;
1140
1141 if ((r = sshbuf_putf(b,
1142 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0)
1143 fatal_fr(r, "sshbuf_putf");
1144
1145 suppress_flags =
1146 (mux_client ? SUPPRESS_MUXCLIENT : 0) |
1147 (mux_client ? 0 : SUPPRESS_MUXMASTER) |
1148 (using_stderr ? 0 : SUPPRESS_SYSLOG) |
1149 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0);
1150
1151 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
1152 if (esc_txt[i].flags & suppress_flags)
1153 continue;
1154 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n",
1155 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0)
1156 fatal_fr(r, "sshbuf_putf");
1157 }
1158
1159 if ((r = sshbuf_putf(b,
1160 " %c%c - send the escape character by typing it twice\r\n"
1161 "(Note that escapes are only recognized immediately after "
1162 "newline.)\r\n", escape_char, escape_char)) != 0)
1163 fatal_fr(r, "sshbuf_putf");
1164 }
1165
1166 /*
1167 * Process the characters one by one.
1168 */
1169 static int
process_escapes(struct ssh * ssh,Channel * c,struct sshbuf * bin,struct sshbuf * bout,struct sshbuf * berr,char * buf,int len)1170 process_escapes(struct ssh *ssh, Channel *c,
1171 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr,
1172 char *buf, int len)
1173 {
1174 pid_t pid;
1175 int r, bytes = 0;
1176 u_int i;
1177 u_char ch;
1178 char *s;
1179 struct escape_filter_ctx *efc;
1180
1181 if (c == NULL || c->filter_ctx == NULL || len <= 0)
1182 return 0;
1183
1184 efc = (struct escape_filter_ctx *)c->filter_ctx;
1185
1186 for (i = 0; i < (u_int)len; i++) {
1187 /* Get one character at a time. */
1188 ch = buf[i];
1189
1190 if (efc->escape_pending) {
1191 /* We have previously seen an escape character. */
1192 /* Clear the flag now. */
1193 efc->escape_pending = 0;
1194
1195 /* Process the escaped character. */
1196 switch (ch) {
1197 case '.':
1198 /* Terminate the connection. */
1199 if ((r = sshbuf_putf(berr, "%c.\r\n",
1200 efc->escape_char)) != 0)
1201 fatal_fr(r, "sshbuf_putf");
1202 if (c && c->ctl_chan != -1) {
1203 channel_force_close(ssh, c, 1);
1204 return 0;
1205 } else
1206 quit_pending = 1;
1207 return -1;
1208
1209 case 'Z' - 64:
1210 /* XXX support this for mux clients */
1211 if (c && c->ctl_chan != -1) {
1212 char b[16];
1213 noescape:
1214 if (ch == 'Z' - 64)
1215 snprintf(b, sizeof b, "^Z");
1216 else
1217 snprintf(b, sizeof b, "%c", ch);
1218 if ((r = sshbuf_putf(berr,
1219 "%c%s escape not available to "
1220 "multiplexed sessions\r\n",
1221 efc->escape_char, b)) != 0)
1222 fatal_fr(r, "sshbuf_putf");
1223 continue;
1224 }
1225 /* Suspend the program. Inform the user */
1226 if ((r = sshbuf_putf(berr,
1227 "%c^Z [suspend ssh]\r\n",
1228 efc->escape_char)) != 0)
1229 fatal_fr(r, "sshbuf_putf");
1230
1231 /* Restore terminal modes and suspend. */
1232 client_suspend_self(bin, bout, berr);
1233
1234 /* We have been continued. */
1235 continue;
1236
1237 case 'B':
1238 if ((r = sshbuf_putf(berr,
1239 "%cB\r\n", efc->escape_char)) != 0)
1240 fatal_fr(r, "sshbuf_putf");
1241 channel_request_start(ssh, c->self, "break", 0);
1242 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 ||
1243 (r = sshpkt_send(ssh)) != 0)
1244 fatal_fr(r, "send packet");
1245 continue;
1246
1247 case 'R':
1248 if (ssh->compat & SSH_BUG_NOREKEY)
1249 logit("Server does not "
1250 "support re-keying");
1251 else
1252 need_rekeying = 1;
1253 continue;
1254
1255 case 'V':
1256 /* FALLTHROUGH */
1257 case 'v':
1258 if (c && c->ctl_chan != -1)
1259 goto noescape;
1260 if (!log_is_on_stderr()) {
1261 if ((r = sshbuf_putf(berr,
1262 "%c%c [Logging to syslog]\r\n",
1263 efc->escape_char, ch)) != 0)
1264 fatal_fr(r, "sshbuf_putf");
1265 continue;
1266 }
1267 if (ch == 'V' && options.log_level >
1268 SYSLOG_LEVEL_QUIET)
1269 log_change_level(--options.log_level);
1270 if (ch == 'v' && options.log_level <
1271 SYSLOG_LEVEL_DEBUG3)
1272 log_change_level(++options.log_level);
1273 if ((r = sshbuf_putf(berr,
1274 "%c%c [LogLevel %s]\r\n",
1275 efc->escape_char, ch,
1276 log_level_name(options.log_level))) != 0)
1277 fatal_fr(r, "sshbuf_putf");
1278 continue;
1279
1280 case '&':
1281 if (c->ctl_chan != -1)
1282 goto noescape;
1283 /*
1284 * Detach the program (continue to serve
1285 * connections, but put in background and no
1286 * more new connections).
1287 */
1288 /* Restore tty modes. */
1289 leave_raw_mode(
1290 options.request_tty == REQUEST_TTY_FORCE);
1291
1292 /* Stop listening for new connections. */
1293 channel_stop_listening(ssh);
1294
1295 if ((r = sshbuf_putf(berr, "%c& "
1296 "[backgrounded]\n", efc->escape_char)) != 0)
1297 fatal_fr(r, "sshbuf_putf");
1298
1299 /* Fork into background. */
1300 pid = fork();
1301 if (pid == -1) {
1302 error("fork: %.100s", strerror(errno));
1303 continue;
1304 }
1305 if (pid != 0) { /* This is the parent. */
1306 /* The parent just exits. */
1307 exit(0);
1308 }
1309 /* The child continues serving connections. */
1310 /* fake EOF on stdin */
1311 if ((r = sshbuf_put_u8(bin, 4)) != 0)
1312 fatal_fr(r, "sshbuf_put_u8");
1313 return -1;
1314 case '?':
1315 print_escape_help(berr, efc->escape_char,
1316 (c && c->ctl_chan != -1),
1317 log_is_on_stderr());
1318 continue;
1319
1320 case '#':
1321 if ((r = sshbuf_putf(berr, "%c#\r\n",
1322 efc->escape_char)) != 0)
1323 fatal_fr(r, "sshbuf_putf");
1324 s = channel_open_message(ssh);
1325 if ((r = sshbuf_put(berr, s, strlen(s))) != 0)
1326 fatal_fr(r, "sshbuf_put");
1327 free(s);
1328 continue;
1329
1330 case 'C':
1331 if (c && c->ctl_chan != -1)
1332 goto noescape;
1333 if (options.enable_escape_commandline == 0) {
1334 if ((r = sshbuf_putf(berr,
1335 "commandline disabled\r\n")) != 0)
1336 fatal_fr(r, "sshbuf_putf");
1337 continue;
1338 }
1339 process_cmdline(ssh);
1340 continue;
1341
1342 default:
1343 if (ch != efc->escape_char) {
1344 if ((r = sshbuf_put_u8(bin,
1345 efc->escape_char)) != 0)
1346 fatal_fr(r, "sshbuf_put_u8");
1347 bytes++;
1348 }
1349 /* Escaped characters fall through here */
1350 break;
1351 }
1352 } else {
1353 /*
1354 * The previous character was not an escape char.
1355 * Check if this is an escape.
1356 */
1357 if (last_was_cr && ch == efc->escape_char) {
1358 /*
1359 * It is. Set the flag and continue to
1360 * next character.
1361 */
1362 efc->escape_pending = 1;
1363 continue;
1364 }
1365 }
1366
1367 /*
1368 * Normal character. Record whether it was a newline,
1369 * and append it to the buffer.
1370 */
1371 last_was_cr = (ch == '\r' || ch == '\n');
1372 if ((r = sshbuf_put_u8(bin, ch)) != 0)
1373 fatal_fr(r, "sshbuf_put_u8");
1374 bytes++;
1375 }
1376 return bytes;
1377 }
1378
1379 /*
1380 * Get packets from the connection input buffer, and process them as long as
1381 * there are packets available.
1382 *
1383 * Any unknown packets received during the actual
1384 * session cause the session to terminate. This is
1385 * intended to make debugging easier since no
1386 * confirmations are sent. Any compatible protocol
1387 * extensions must be negotiated during the
1388 * preparatory phase.
1389 */
1390
1391 static void
client_process_buffered_input_packets(struct ssh * ssh)1392 client_process_buffered_input_packets(struct ssh *ssh)
1393 {
1394 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending);
1395 }
1396
1397 /* scan buf[] for '~' before sending data to the peer */
1398
1399 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */
1400 void *
client_new_escape_filter_ctx(int escape_char)1401 client_new_escape_filter_ctx(int escape_char)
1402 {
1403 struct escape_filter_ctx *ret;
1404
1405 ret = xcalloc(1, sizeof(*ret));
1406 ret->escape_pending = 0;
1407 ret->escape_char = escape_char;
1408 return (void *)ret;
1409 }
1410
1411 /* Free the escape filter context on channel free */
1412 void
client_filter_cleanup(struct ssh * ssh,int cid,void * ctx)1413 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx)
1414 {
1415 free(ctx);
1416 }
1417
1418 int
client_simple_escape_filter(struct ssh * ssh,Channel * c,char * buf,int len)1419 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len)
1420 {
1421 if (c->extended_usage != CHAN_EXTENDED_WRITE)
1422 return 0;
1423
1424 return process_escapes(ssh, c, c->input, c->output, c->extended,
1425 buf, len);
1426 }
1427
1428 static void
client_channel_closed(struct ssh * ssh,int id,int force,void * arg)1429 client_channel_closed(struct ssh *ssh, int id, int force, void *arg)
1430 {
1431 channel_cancel_cleanup(ssh, id);
1432 session_closed = 1;
1433 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1434 }
1435
1436 /*
1437 * Implements the interactive session with the server. This is called after
1438 * the user has been authenticated, and a command has been started on the
1439 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character
1440 * used as an escape character for terminating or suspending the session.
1441 */
1442 int
client_loop(struct ssh * ssh,int have_pty,int escape_char_arg,int ssh2_chan_id)1443 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
1444 int ssh2_chan_id)
1445 {
1446 struct pollfd *pfd = NULL;
1447 u_int npfd_alloc = 0, npfd_active = 0;
1448 double start_time, total_time;
1449 int channel_did_enqueue = 0, r, len;
1450 u_int64_t ibytes, obytes;
1451 int conn_in_ready, conn_out_ready;
1452 sigset_t bsigset, osigset;
1453
1454 debug("Entering interactive session.");
1455 session_ident = ssh2_chan_id;
1456
1457 if (options.control_master &&
1458 !option_clear_or_none(options.control_path)) {
1459 debug("pledge: id");
1460 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty",
1461 NULL) == -1)
1462 fatal_f("pledge(): %s", strerror(errno));
1463
1464 } else if (options.forward_x11 || options.permit_local_command) {
1465 debug("pledge: exec");
1466 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty",
1467 NULL) == -1)
1468 fatal_f("pledge(): %s", strerror(errno));
1469
1470 } else if (options.update_hostkeys) {
1471 debug("pledge: filesystem");
1472 if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
1473 NULL) == -1)
1474 fatal_f("pledge(): %s", strerror(errno));
1475
1476 } else if (!option_clear_or_none(options.proxy_command) ||
1477 options.fork_after_authentication) {
1478 debug("pledge: proc");
1479 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
1480 fatal_f("pledge(): %s", strerror(errno));
1481
1482 } else {
1483 debug("pledge: network");
1484 if (pledge("stdio unix inet dns proc tty", NULL) == -1)
1485 fatal_f("pledge(): %s", strerror(errno));
1486 }
1487
1488 /* might be able to tighten now */
1489 client_repledge();
1490
1491 start_time = monotime_double();
1492
1493 /* Initialize variables. */
1494 last_was_cr = 1;
1495 exit_status = -1;
1496 connection_in = ssh_packet_get_connection_in(ssh);
1497 connection_out = ssh_packet_get_connection_out(ssh);
1498
1499 quit_pending = 0;
1500
1501 /* Initialize buffer. */
1502 if ((stderr_buffer = sshbuf_new()) == NULL)
1503 fatal_f("sshbuf_new failed");
1504
1505 client_init_dispatch(ssh);
1506
1507 /*
1508 * Set signal handlers, (e.g. to restore non-blocking mode)
1509 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
1510 */
1511 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN)
1512 ssh_signal(SIGHUP, signal_handler);
1513 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN)
1514 ssh_signal(SIGINT, signal_handler);
1515 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN)
1516 ssh_signal(SIGQUIT, signal_handler);
1517 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN)
1518 ssh_signal(SIGTERM, signal_handler);
1519 ssh_signal(SIGWINCH, window_change_handler);
1520
1521 if (have_pty)
1522 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1523
1524 if (session_ident != -1) {
1525 if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
1526 channel_register_filter(ssh, session_ident,
1527 client_simple_escape_filter, NULL,
1528 client_filter_cleanup,
1529 client_new_escape_filter_ctx(
1530 escape_char_arg));
1531 }
1532 channel_register_cleanup(ssh, session_ident,
1533 client_channel_closed, 0);
1534 }
1535
1536 schedule_server_alive_check();
1537
1538 if (sigemptyset(&bsigset) == -1 ||
1539 sigaddset(&bsigset, SIGHUP) == -1 ||
1540 sigaddset(&bsigset, SIGINT) == -1 ||
1541 sigaddset(&bsigset, SIGQUIT) == -1 ||
1542 sigaddset(&bsigset, SIGTERM) == -1)
1543 error_f("bsigset setup: %s", strerror(errno));
1544
1545 /* Main loop of the client for the interactive session mode. */
1546 while (!quit_pending) {
1547 channel_did_enqueue = 0;
1548
1549 /* Process buffered packets sent by the server. */
1550 client_process_buffered_input_packets(ssh);
1551
1552 if (session_closed && !channel_still_open(ssh))
1553 break;
1554
1555 if (ssh_packet_is_rekeying(ssh)) {
1556 debug("rekeying in progress");
1557 } else if (need_rekeying) {
1558 /* manual rekey request */
1559 debug("need rekeying");
1560 if ((r = kex_start_rekex(ssh)) != 0)
1561 fatal_fr(r, "kex_start_rekex");
1562 need_rekeying = 0;
1563 } else {
1564 /*
1565 * Make packets from buffered channel data, and
1566 * enqueue them for sending to the server.
1567 */
1568 if (ssh_packet_not_very_much_data_to_write(ssh))
1569 channel_did_enqueue = channel_output_poll(ssh);
1570
1571 /*
1572 * Check if the window size has changed, and buffer a
1573 * message about it to the server if so.
1574 */
1575 client_check_window_change(ssh);
1576 }
1577 /*
1578 * Wait until we have something to do (something becomes
1579 * available on one of the descriptors).
1580 */
1581 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1)
1582 error_f("bsigset sigprocmask: %s", strerror(errno));
1583 if (quit_pending)
1584 break;
1585 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc,
1586 &npfd_active, channel_did_enqueue, &osigset,
1587 &conn_in_ready, &conn_out_ready);
1588 if (sigprocmask(SIG_UNBLOCK, &bsigset, &osigset) == -1)
1589 error_f("osigset sigprocmask: %s", strerror(errno));
1590
1591 if (quit_pending)
1592 break;
1593
1594 /* Do channel operations. */
1595 channel_after_poll(ssh, pfd, npfd_active);
1596
1597 /* Buffer input from the connection. */
1598 if (conn_in_ready)
1599 client_process_net_input(ssh);
1600
1601 if (quit_pending)
1602 break;
1603
1604 /* A timeout may have triggered rekeying */
1605 if ((r = ssh_packet_check_rekey(ssh)) != 0)
1606 fatal_fr(r, "cannot start rekeying");
1607
1608 /*
1609 * Send as much buffered packet data as possible to the
1610 * sender.
1611 */
1612 if (conn_out_ready) {
1613 if ((r = ssh_packet_write_poll(ssh)) != 0) {
1614 sshpkt_fatal(ssh, r,
1615 "%s: ssh_packet_write_poll", __func__);
1616 }
1617 }
1618
1619 /*
1620 * If we are a backgrounded control master, and the
1621 * timeout has expired without any active client
1622 * connections, then quit.
1623 */
1624 if (control_persist_exit_time > 0) {
1625 if (monotime() >= control_persist_exit_time) {
1626 debug("ControlPersist timeout expired");
1627 break;
1628 }
1629 }
1630 }
1631 free(pfd);
1632
1633 /* Terminate the session. */
1634
1635 /* Stop watching for window change. */
1636 ssh_signal(SIGWINCH, SIG_DFL);
1637
1638 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
1639 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 ||
1640 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 ||
1641 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */
1642 (r = sshpkt_send(ssh)) != 0 ||
1643 (r = ssh_packet_write_wait(ssh)) != 0)
1644 fatal_fr(r, "send disconnect");
1645
1646 channel_free_all(ssh);
1647
1648 if (have_pty)
1649 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1650
1651 /*
1652 * If there was no shell or command requested, there will be no remote
1653 * exit status to be returned. In that case, clear error code if the
1654 * connection was deliberately terminated at this end.
1655 */
1656 if (options.session_type == SESSION_TYPE_NONE &&
1657 received_signal == SIGTERM) {
1658 received_signal = 0;
1659 exit_status = 0;
1660 }
1661
1662 if (received_signal) {
1663 verbose("Killed by signal %d.", (int) received_signal);
1664 cleanup_exit(255);
1665 }
1666
1667 /*
1668 * In interactive mode (with pseudo tty) display a message indicating
1669 * that the connection has been closed.
1670 */
1671 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO)
1672 quit_message("Connection to %s closed.", host);
1673
1674 /* Output any buffered data for stderr. */
1675 if (sshbuf_len(stderr_buffer) > 0) {
1676 len = atomicio(vwrite, fileno(stderr),
1677 (u_char *)sshbuf_ptr(stderr_buffer),
1678 sshbuf_len(stderr_buffer));
1679 if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer))
1680 error("Write failed flushing stderr buffer.");
1681 else if ((r = sshbuf_consume(stderr_buffer, len)) != 0)
1682 fatal_fr(r, "sshbuf_consume");
1683 }
1684
1685 /* Clear and free any buffers. */
1686 sshbuf_free(stderr_buffer);
1687
1688 /* Report bytes transferred, and transfer rates. */
1689 total_time = monotime_double() - start_time;
1690 ssh_packet_get_bytes(ssh, &ibytes, &obytes);
1691 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
1692 (unsigned long long)obytes, (unsigned long long)ibytes, total_time);
1693 if (total_time > 0)
1694 verbose("Bytes per second: sent %.1f, received %.1f",
1695 obytes / total_time, ibytes / total_time);
1696 /* Return the exit status of the program. */
1697 debug("Exit status %d", exit_status);
1698 return exit_status;
1699 }
1700
1701 /*********/
1702
1703 static Channel *
client_request_forwarded_tcpip(struct ssh * ssh,const char * request_type,int rchan,u_int rwindow,u_int rmaxpack)1704 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
1705 int rchan, u_int rwindow, u_int rmaxpack)
1706 {
1707 Channel *c = NULL;
1708 struct sshbuf *b = NULL;
1709 char *listen_address, *originator_address;
1710 u_int listen_port, originator_port;
1711 int r;
1712
1713 /* Get rest of the packet */
1714 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 ||
1715 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 ||
1716 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 ||
1717 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
1718 (r = sshpkt_get_end(ssh)) != 0)
1719 fatal_fr(r, "parse packet");
1720
1721 debug_f("listen %s port %d, originator %s port %d",
1722 listen_address, listen_port, originator_address, originator_port);
1723
1724 if (listen_port > 0xffff)
1725 error_f("invalid listen port");
1726 else if (originator_port > 0xffff)
1727 error_f("invalid originator port");
1728 else {
1729 c = channel_connect_by_listen_address(ssh,
1730 listen_address, listen_port, "forwarded-tcpip",
1731 originator_address);
1732 }
1733
1734 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1735 if ((b = sshbuf_new()) == NULL) {
1736 error_f("alloc reply");
1737 goto out;
1738 }
1739 /* reconstruct and send to muxclient */
1740 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
1741 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1742 (r = sshbuf_put_cstring(b, request_type)) != 0 ||
1743 (r = sshbuf_put_u32(b, rchan)) != 0 ||
1744 (r = sshbuf_put_u32(b, rwindow)) != 0 ||
1745 (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
1746 (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
1747 (r = sshbuf_put_u32(b, listen_port)) != 0 ||
1748 (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
1749 (r = sshbuf_put_u32(b, originator_port)) != 0 ||
1750 (r = sshbuf_put_stringb(c->output, b)) != 0) {
1751 error_fr(r, "compose for muxclient");
1752 goto out;
1753 }
1754 }
1755
1756 out:
1757 sshbuf_free(b);
1758 free(originator_address);
1759 free(listen_address);
1760 return c;
1761 }
1762
1763 static Channel *
client_request_forwarded_streamlocal(struct ssh * ssh,const char * request_type,int rchan)1764 client_request_forwarded_streamlocal(struct ssh *ssh,
1765 const char *request_type, int rchan)
1766 {
1767 Channel *c = NULL;
1768 char *listen_path;
1769 int r;
1770
1771 /* Get the remote path. */
1772 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 ||
1773 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */
1774 (r = sshpkt_get_end(ssh)) != 0)
1775 fatal_fr(r, "parse packet");
1776
1777 debug_f("request: %s", listen_path);
1778
1779 c = channel_connect_by_listen_path(ssh, listen_path,
1780 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
1781 free(listen_path);
1782 return c;
1783 }
1784
1785 static Channel *
client_request_x11(struct ssh * ssh,const char * request_type,int rchan)1786 client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
1787 {
1788 Channel *c = NULL;
1789 char *originator;
1790 u_int originator_port;
1791 int r, sock;
1792
1793 if (!options.forward_x11) {
1794 error("Warning: ssh server tried X11 forwarding.");
1795 error("Warning: this is probably a break-in attempt by a "
1796 "malicious server.");
1797 return NULL;
1798 }
1799 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) {
1800 verbose("Rejected X11 connection after ForwardX11Timeout "
1801 "expired");
1802 return NULL;
1803 }
1804 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
1805 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
1806 (r = sshpkt_get_end(ssh)) != 0)
1807 fatal_fr(r, "parse packet");
1808 /* XXX check permission */
1809 /* XXX range check originator port? */
1810 debug("client_request_x11: request from %s %u", originator,
1811 originator_port);
1812 free(originator);
1813 sock = x11_connect_display(ssh);
1814 if (sock < 0)
1815 return NULL;
1816 c = channel_new(ssh, "x11-connection",
1817 SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1818 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1819 c->force_drain = 1;
1820 return c;
1821 }
1822
1823 static Channel *
client_request_agent(struct ssh * ssh,const char * request_type,int rchan)1824 client_request_agent(struct ssh *ssh, const char *request_type, int rchan)
1825 {
1826 Channel *c = NULL;
1827 int r, sock;
1828
1829 if (!options.forward_agent) {
1830 error("Warning: ssh server tried agent forwarding.");
1831 error("Warning: this is probably a break-in attempt by a "
1832 "malicious server.");
1833 return NULL;
1834 }
1835 if (forward_agent_sock_path == NULL) {
1836 r = ssh_get_authentication_socket(&sock);
1837 } else {
1838 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock);
1839 }
1840 if (r != 0) {
1841 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1842 debug_fr(r, "ssh_get_authentication_socket");
1843 return NULL;
1844 }
1845 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey,
1846 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0)
1847 debug_f("bound agent to hostkey");
1848 else
1849 debug2_fr(r, "ssh_agent_bind_hostkey");
1850
1851 c = channel_new(ssh, "agent-connection",
1852 SSH_CHANNEL_OPEN, sock, sock, -1,
1853 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
1854 "authentication agent connection", 1);
1855 c->force_drain = 1;
1856 return c;
1857 }
1858
1859 char *
client_request_tun_fwd(struct ssh * ssh,int tun_mode,int local_tun,int remote_tun,channel_open_fn * cb,void * cbctx)1860 client_request_tun_fwd(struct ssh *ssh, int tun_mode,
1861 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx)
1862 {
1863 Channel *c;
1864 int r, fd;
1865 char *ifname = NULL;
1866
1867 if (tun_mode == SSH_TUNMODE_NO)
1868 return 0;
1869
1870 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);
1871
1872 /* Open local tunnel device */
1873 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) {
1874 error("Tunnel device open failed.");
1875 return NULL;
1876 }
1877 debug("Tunnel forwarding using interface %s", ifname);
1878
1879 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1,
1880 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1881 c->datagram = 1;
1882
1883 #if defined(SSH_TUN_FILTER)
1884 if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1885 channel_register_filter(ssh, c->self, sys_tun_infilter,
1886 sys_tun_outfilter, NULL, NULL);
1887 #endif
1888
1889 if (cb != NULL)
1890 channel_register_open_confirm(ssh, c->self, cb, cbctx);
1891
1892 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1893 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 ||
1894 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
1895 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 ||
1896 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
1897 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 ||
1898 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 ||
1899 (r = sshpkt_send(ssh)) != 0)
1900 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
1901
1902 return ifname;
1903 }
1904
1905 /* XXXX move to generic input handler */
1906 static int
client_input_channel_open(int type,u_int32_t seq,struct ssh * ssh)1907 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
1908 {
1909 Channel *c = NULL;
1910 char *ctype = NULL;
1911 int r;
1912 u_int rchan;
1913 size_t len;
1914 u_int rmaxpack, rwindow;
1915
1916 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 ||
1917 (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
1918 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
1919 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
1920 goto out;
1921
1922 debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
1923 ctype, rchan, rwindow, rmaxpack);
1924
1925 if (strcmp(ctype, "forwarded-tcpip") == 0) {
1926 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow,
1927 rmaxpack);
1928 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
1929 c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
1930 } else if (strcmp(ctype, "x11") == 0) {
1931 c = client_request_x11(ssh, ctype, rchan);
1932 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
1933 c = client_request_agent(ssh, ctype, rchan);
1934 }
1935 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1936 debug3("proxied to downstream: %s", ctype);
1937 } else if (c != NULL) {
1938 debug("confirm %s", ctype);
1939 c->remote_id = rchan;
1940 c->have_remote_id = 1;
1941 c->remote_window = rwindow;
1942 c->remote_maxpacket = rmaxpack;
1943 if (c->type != SSH_CHANNEL_CONNECTING) {
1944 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
1945 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
1946 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
1947 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
1948 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
1949 (r = sshpkt_send(ssh)) != 0)
1950 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
1951 }
1952 } else {
1953 debug("failure %s", ctype);
1954 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
1955 (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
1956 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 ||
1957 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 ||
1958 (r = sshpkt_put_cstring(ssh, "")) != 0 ||
1959 (r = sshpkt_send(ssh)) != 0)
1960 sshpkt_fatal(ssh, r, "%s: send failure", __func__);
1961 }
1962 r = 0;
1963 out:
1964 free(ctype);
1965 return r;
1966 }
1967
1968 static int
client_input_channel_req(int type,u_int32_t seq,struct ssh * ssh)1969 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
1970 {
1971 Channel *c = NULL;
1972 char *rtype = NULL;
1973 u_char reply;
1974 u_int id, exitval;
1975 int r, success = 0;
1976
1977 if ((r = sshpkt_get_u32(ssh, &id)) != 0)
1978 return r;
1979 if (id <= INT_MAX)
1980 c = channel_lookup(ssh, id);
1981 if (channel_proxy_upstream(c, type, seq, ssh))
1982 return 0;
1983 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
1984 (r = sshpkt_get_u8(ssh, &reply)) != 0)
1985 goto out;
1986
1987 debug("client_input_channel_req: channel %u rtype %s reply %d",
1988 id, rtype, reply);
1989
1990 if (c == NULL) {
1991 error("client_input_channel_req: channel %d: "
1992 "unknown channel", id);
1993 } else if (strcmp(rtype, "eow@openssh.com") == 0) {
1994 if ((r = sshpkt_get_end(ssh)) != 0)
1995 goto out;
1996 chan_rcvd_eow(ssh, c);
1997 } else if (strcmp(rtype, "exit-status") == 0) {
1998 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0)
1999 goto out;
2000 if (c->ctl_chan != -1) {
2001 mux_exit_message(ssh, c, exitval);
2002 success = 1;
2003 } else if ((int)id == session_ident) {
2004 /* Record exit value of local session */
2005 success = 1;
2006 exit_status = exitval;
2007 } else {
2008 /* Probably for a mux channel that has already closed */
2009 debug_f("no sink for exit-status on channel %d",
2010 id);
2011 }
2012 if ((r = sshpkt_get_end(ssh)) != 0)
2013 goto out;
2014 }
2015 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
2016 if (!c->have_remote_id)
2017 fatal_f("channel %d: no remote_id", c->self);
2018 if ((r = sshpkt_start(ssh, success ?
2019 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
2020 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
2021 (r = sshpkt_send(ssh)) != 0)
2022 sshpkt_fatal(ssh, r, "%s: send failure", __func__);
2023 }
2024 r = 0;
2025 out:
2026 free(rtype);
2027 return r;
2028 }
2029
2030 struct hostkeys_update_ctx {
2031 /* The hostname and (optionally) IP address string for the server */
2032 char *host_str, *ip_str;
2033
2034 /*
2035 * Keys received from the server and a flag for each indicating
2036 * whether they already exist in known_hosts.
2037 * keys_match is filled in by hostkeys_find() and later (for new
2038 * keys) by client_global_hostkeys_prove_confirm().
2039 */
2040 struct sshkey **keys;
2041 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */
2042 int *keys_verified; /* flag for new keys verified by server */
2043 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */
2044
2045 /*
2046 * Keys that are in known_hosts, but were not present in the update
2047 * from the server (i.e. scheduled to be deleted).
2048 * Filled in by hostkeys_find().
2049 */
2050 struct sshkey **old_keys;
2051 size_t nold;
2052
2053 /* Various special cases. */
2054 int complex_hostspec; /* wildcard or manual pattern-list host name */
2055 int ca_available; /* saw CA key for this host */
2056 int old_key_seen; /* saw old key with other name/addr */
2057 int other_name_seen; /* saw key with other name/addr */
2058 };
2059
2060 static void
hostkeys_update_ctx_free(struct hostkeys_update_ctx * ctx)2061 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
2062 {
2063 size_t i;
2064
2065 if (ctx == NULL)
2066 return;
2067 for (i = 0; i < ctx->nkeys; i++)
2068 sshkey_free(ctx->keys[i]);
2069 free(ctx->keys);
2070 free(ctx->keys_match);
2071 free(ctx->keys_verified);
2072 for (i = 0; i < ctx->nold; i++)
2073 sshkey_free(ctx->old_keys[i]);
2074 free(ctx->old_keys);
2075 free(ctx->host_str);
2076 free(ctx->ip_str);
2077 free(ctx);
2078 }
2079
2080 /*
2081 * Returns non-zero if a known_hosts hostname list is not of a form that
2082 * can be handled by UpdateHostkeys. These include wildcard hostnames and
2083 * hostnames lists that do not follow the form host[,ip].
2084 */
2085 static int
hostspec_is_complex(const char * hosts)2086 hostspec_is_complex(const char *hosts)
2087 {
2088 char *cp;
2089
2090 /* wildcard */
2091 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL)
2092 return 1;
2093 /* single host/ip = ok */
2094 if ((cp = strchr(hosts, ',')) == NULL)
2095 return 0;
2096 /* more than two entries on the line */
2097 if (strchr(cp + 1, ',') != NULL)
2098 return 1;
2099 /* XXX maybe parse cp+1 and ensure it is an IP? */
2100 return 0;
2101 }
2102
2103 /* callback to search for ctx->keys in known_hosts */
2104 static int
hostkeys_find(struct hostkey_foreach_line * l,void * _ctx)2105 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
2106 {
2107 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2108 size_t i;
2109 struct sshkey **tmp;
2110
2111 if (l->key == NULL)
2112 return 0;
2113 if (l->status != HKF_STATUS_MATCHED) {
2114 /* Record if one of the keys appears on a non-matching line */
2115 for (i = 0; i < ctx->nkeys; i++) {
2116 if (sshkey_equal(l->key, ctx->keys[i])) {
2117 ctx->other_name_seen = 1;
2118 debug3_f("found %s key under different "
2119 "name/addr at %s:%ld",
2120 sshkey_ssh_name(ctx->keys[i]),
2121 l->path, l->linenum);
2122 return 0;
2123 }
2124 }
2125 return 0;
2126 }
2127 /* Don't proceed if revocation or CA markers are present */
2128 /* XXX relax this */
2129 if (l->marker != MRK_NONE) {
2130 debug3_f("hostkeys file %s:%ld has CA/revocation marker",
2131 l->path, l->linenum);
2132 ctx->complex_hostspec = 1;
2133 return 0;
2134 }
2135
2136 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */
2137 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) {
2138 if ((l->match & HKF_MATCH_HOST) == 0) {
2139 /* Record if address matched a different hostname. */
2140 ctx->other_name_seen = 1;
2141 debug3_f("found address %s against different hostname "
2142 "at %s:%ld", ctx->ip_str, l->path, l->linenum);
2143 return 0;
2144 } else if ((l->match & HKF_MATCH_IP) == 0) {
2145 /* Record if hostname matched a different address. */
2146 ctx->other_name_seen = 1;
2147 debug3_f("found hostname %s against different address "
2148 "at %s:%ld", ctx->host_str, l->path, l->linenum);
2149 }
2150 }
2151
2152 /*
2153 * UpdateHostkeys is skipped for wildcard host names and hostnames
2154 * that contain more than two entries (ssh never writes these).
2155 */
2156 if (hostspec_is_complex(l->hosts)) {
2157 debug3_f("hostkeys file %s:%ld complex host specification",
2158 l->path, l->linenum);
2159 ctx->complex_hostspec = 1;
2160 return 0;
2161 }
2162
2163 /* Mark off keys we've already seen for this host */
2164 for (i = 0; i < ctx->nkeys; i++) {
2165 if (!sshkey_equal(l->key, ctx->keys[i]))
2166 continue;
2167 debug3_f("found %s key at %s:%ld",
2168 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
2169 ctx->keys_match[i] |= l->match;
2170 return 0;
2171 }
2172 /* This line contained a key that not offered by the server */
2173 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key),
2174 l->path, l->linenum);
2175 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1,
2176 sizeof(*ctx->old_keys))) == NULL)
2177 fatal_f("recallocarray failed nold = %zu", ctx->nold);
2178 ctx->old_keys = tmp;
2179 ctx->old_keys[ctx->nold++] = l->key;
2180 l->key = NULL;
2181
2182 return 0;
2183 }
2184
2185 /* callback to search for ctx->old_keys in known_hosts under other names */
2186 static int
hostkeys_check_old(struct hostkey_foreach_line * l,void * _ctx)2187 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx)
2188 {
2189 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2190 size_t i;
2191 int hashed;
2192
2193 /* only care about lines that *don't* match the active host spec */
2194 if (l->status == HKF_STATUS_MATCHED || l->key == NULL)
2195 return 0;
2196
2197 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED);
2198 for (i = 0; i < ctx->nold; i++) {
2199 if (!sshkey_equal(l->key, ctx->old_keys[i]))
2200 continue;
2201 debug3_f("found deprecated %s key at %s:%ld as %s",
2202 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum,
2203 hashed ? "[HASHED]" : l->hosts);
2204 ctx->old_key_seen = 1;
2205 break;
2206 }
2207 return 0;
2208 }
2209
2210 /*
2211 * Check known_hosts files for deprecated keys under other names. Returns 0
2212 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys
2213 * exist under names other than the active hostname/IP.
2214 */
2215 static int
check_old_keys_othernames(struct hostkeys_update_ctx * ctx)2216 check_old_keys_othernames(struct hostkeys_update_ctx *ctx)
2217 {
2218 size_t i;
2219 int r;
2220
2221 debug2_f("checking for %zu deprecated keys", ctx->nold);
2222 for (i = 0; i < options.num_user_hostfiles; i++) {
2223 debug3_f("searching %s for %s / %s",
2224 options.user_hostfiles[i], ctx->host_str,
2225 ctx->ip_str ? ctx->ip_str : "(none)");
2226 if ((r = hostkeys_foreach(options.user_hostfiles[i],
2227 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str,
2228 HKF_WANT_PARSE_KEY, 0)) != 0) {
2229 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
2230 debug_f("hostkeys file %s does not exist",
2231 options.user_hostfiles[i]);
2232 continue;
2233 }
2234 error_fr(r, "hostkeys_foreach failed for %s",
2235 options.user_hostfiles[i]);
2236 return -1;
2237 }
2238 }
2239 return 0;
2240 }
2241
2242 static void
hostkey_change_preamble(LogLevel loglevel)2243 hostkey_change_preamble(LogLevel loglevel)
2244 {
2245 do_log2(loglevel, "The server has updated its host keys.");
2246 do_log2(loglevel, "These changes were verified by the server's "
2247 "existing trusted key.");
2248 }
2249
2250 static void
update_known_hosts(struct hostkeys_update_ctx * ctx)2251 update_known_hosts(struct hostkeys_update_ctx *ctx)
2252 {
2253 int r, was_raw = 0, first = 1;
2254 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK;
2255 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
2256 char *fp, *response;
2257 size_t i;
2258 struct stat sb;
2259
2260 for (i = 0; i < ctx->nkeys; i++) {
2261 if (!ctx->keys_verified[i])
2262 continue;
2263 if ((fp = sshkey_fingerprint(ctx->keys[i],
2264 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2265 fatal_f("sshkey_fingerprint failed");
2266 if (first && asking)
2267 hostkey_change_preamble(loglevel);
2268 do_log2(loglevel, "Learned new hostkey: %s %s",
2269 sshkey_type(ctx->keys[i]), fp);
2270 first = 0;
2271 free(fp);
2272 }
2273 for (i = 0; i < ctx->nold; i++) {
2274 if ((fp = sshkey_fingerprint(ctx->old_keys[i],
2275 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2276 fatal_f("sshkey_fingerprint failed");
2277 if (first && asking)
2278 hostkey_change_preamble(loglevel);
2279 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
2280 sshkey_type(ctx->old_keys[i]), fp);
2281 first = 0;
2282 free(fp);
2283 }
2284 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
2285 if (get_saved_tio() != NULL) {
2286 leave_raw_mode(1);
2287 was_raw = 1;
2288 }
2289 response = NULL;
2290 for (i = 0; !quit_pending && i < 3; i++) {
2291 free(response);
2292 response = read_passphrase("Accept updated hostkeys? "
2293 "(yes/no): ", RP_ECHO);
2294 if (response != NULL && strcasecmp(response, "yes") == 0)
2295 break;
2296 else if (quit_pending || response == NULL ||
2297 strcasecmp(response, "no") == 0) {
2298 options.update_hostkeys = 0;
2299 break;
2300 } else {
2301 do_log2(loglevel, "Please enter "
2302 "\"yes\" or \"no\"");
2303 }
2304 }
2305 if (quit_pending || i >= 3 || response == NULL)
2306 options.update_hostkeys = 0;
2307 free(response);
2308 if (was_raw)
2309 enter_raw_mode(1);
2310 }
2311 if (options.update_hostkeys == 0)
2312 return;
2313 /*
2314 * Now that all the keys are verified, we can go ahead and replace
2315 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
2316 * cancel the operation).
2317 */
2318 for (i = 0; i < options.num_user_hostfiles; i++) {
2319 /*
2320 * NB. keys are only added to hostfiles[0], for the rest we
2321 * just delete the hostname entries.
2322 */
2323 if (stat(options.user_hostfiles[i], &sb) != 0) {
2324 if (errno == ENOENT) {
2325 debug_f("known hosts file %s does not "
2326 "exist", options.user_hostfiles[i]);
2327 } else {
2328 error_f("known hosts file %s "
2329 "inaccessible: %s",
2330 options.user_hostfiles[i], strerror(errno));
2331 }
2332 continue;
2333 }
2334 if ((r = hostfile_replace_entries(options.user_hostfiles[i],
2335 ctx->host_str, ctx->ip_str,
2336 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0,
2337 options.hash_known_hosts, 0,
2338 options.fingerprint_hash)) != 0) {
2339 error_fr(r, "hostfile_replace_entries failed for %s",
2340 options.user_hostfiles[i]);
2341 }
2342 }
2343 }
2344
2345 static void
client_global_hostkeys_prove_confirm(struct ssh * ssh,int type,u_int32_t seq,void * _ctx)2346 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type,
2347 u_int32_t seq, void *_ctx)
2348 {
2349 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2350 size_t i, ndone;
2351 struct sshbuf *signdata;
2352 int r, plaintype;
2353 const u_char *sig;
2354 const char *rsa_kexalg = NULL;
2355 char *alg = NULL;
2356 size_t siglen;
2357
2358 if (ctx->nnew == 0)
2359 fatal_f("ctx->nnew == 0"); /* sanity */
2360 if (type != SSH2_MSG_REQUEST_SUCCESS) {
2361 error("Server failed to confirm ownership of "
2362 "private host keys");
2363 hostkeys_update_ctx_free(ctx);
2364 return;
2365 }
2366 if (sshkey_type_plain(sshkey_type_from_name(
2367 ssh->kex->hostkey_alg)) == KEY_RSA)
2368 rsa_kexalg = ssh->kex->hostkey_alg;
2369 if ((signdata = sshbuf_new()) == NULL)
2370 fatal_f("sshbuf_new failed");
2371 /*
2372 * Expect a signature for each of the ctx->nnew private keys we
2373 * haven't seen before. They will be in the same order as the
2374 * ctx->keys where the corresponding ctx->keys_match[i] == 0.
2375 */
2376 for (ndone = i = 0; i < ctx->nkeys; i++) {
2377 if (ctx->keys_match[i])
2378 continue;
2379 plaintype = sshkey_type_plain(ctx->keys[i]->type);
2380 /* Prepare data to be signed: session ID, unique string, key */
2381 sshbuf_reset(signdata);
2382 if ( (r = sshbuf_put_cstring(signdata,
2383 "hostkeys-prove-00@openssh.com")) != 0 ||
2384 (r = sshbuf_put_stringb(signdata,
2385 ssh->kex->session_id)) != 0 ||
2386 (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
2387 fatal_fr(r, "compose signdata");
2388 /* Extract and verify signature */
2389 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
2390 error_fr(r, "parse sig");
2391 goto out;
2392 }
2393 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) {
2394 error_fr(r, "server gave unintelligible signature "
2395 "for %s key %zu", sshkey_type(ctx->keys[i]), i);
2396 goto out;
2397 }
2398 /*
2399 * Special case for RSA keys: if a RSA hostkey was negotiated,
2400 * then use its signature type for verification of RSA hostkey
2401 * proofs. Otherwise, accept only RSA-SHA256/512 signatures.
2402 */
2403 if (plaintype == KEY_RSA && rsa_kexalg == NULL &&
2404 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) {
2405 debug_f("server used untrusted RSA signature algorithm "
2406 "%s for key %zu, disregarding", alg, i);
2407 free(alg);
2408 /* zap the key from the list */
2409 sshkey_free(ctx->keys[i]);
2410 ctx->keys[i] = NULL;
2411 ndone++;
2412 continue;
2413 }
2414 debug3_f("verify %s key %zu using sigalg %s",
2415 sshkey_type(ctx->keys[i]), i, alg);
2416 free(alg);
2417 if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
2418 sshbuf_ptr(signdata), sshbuf_len(signdata),
2419 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) {
2420 error_fr(r, "server gave bad signature for %s key %zu",
2421 sshkey_type(ctx->keys[i]), i);
2422 goto out;
2423 }
2424 /* Key is good. Mark it as 'seen' */
2425 ctx->keys_verified[i] = 1;
2426 ndone++;
2427 }
2428 /* Shouldn't happen */
2429 if (ndone != ctx->nnew)
2430 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew);
2431 if ((r = sshpkt_get_end(ssh)) != 0) {
2432 error_f("protocol error");
2433 goto out;
2434 }
2435
2436 /* Make the edits to known_hosts */
2437 update_known_hosts(ctx);
2438 out:
2439 hostkeys_update_ctx_free(ctx);
2440 hostkeys_update_complete = 1;
2441 client_repledge();
2442 }
2443
2444 /*
2445 * Returns non-zero if the key is accepted by HostkeyAlgorithms.
2446 * Made slightly less trivial by the multiple RSA signature algorithm names.
2447 */
2448 static int
key_accepted_by_hostkeyalgs(const struct sshkey * key)2449 key_accepted_by_hostkeyalgs(const struct sshkey *key)
2450 {
2451 const char *ktype = sshkey_ssh_name(key);
2452 const char *hostkeyalgs = options.hostkeyalgorithms;
2453
2454 if (key->type == KEY_UNSPEC)
2455 return 0;
2456 if (key->type == KEY_RSA &&
2457 (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 ||
2458 match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1))
2459 return 1;
2460 return match_pattern_list(ktype, hostkeyalgs, 0) == 1;
2461 }
2462
2463 /*
2464 * Handle hostkeys-00@openssh.com global request to inform the client of all
2465 * the server's hostkeys. The keys are checked against the user's
2466 * HostkeyAlgorithms preference before they are accepted.
2467 */
2468 static int
client_input_hostkeys(struct ssh * ssh)2469 client_input_hostkeys(struct ssh *ssh)
2470 {
2471 const u_char *blob = NULL;
2472 size_t i, len = 0;
2473 struct sshbuf *buf = NULL;
2474 struct sshkey *key = NULL, **tmp;
2475 int r, prove_sent = 0;
2476 char *fp;
2477 static int hostkeys_seen = 0; /* XXX use struct ssh */
2478 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
2479 struct hostkeys_update_ctx *ctx = NULL;
2480 u_int want;
2481
2482 if (hostkeys_seen)
2483 fatal_f("server already sent hostkeys");
2484 if (!can_update_hostkeys())
2485 return 1;
2486 hostkeys_seen = 1;
2487
2488 ctx = xcalloc(1, sizeof(*ctx));
2489 while (ssh_packet_remaining(ssh) > 0) {
2490 sshkey_free(key);
2491 key = NULL;
2492 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
2493 error_fr(r, "parse key");
2494 goto out;
2495 }
2496 if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
2497 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ?
2498 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR,
2499 "convert key");
2500 continue;
2501 }
2502 fp = sshkey_fingerprint(key, options.fingerprint_hash,
2503 SSH_FP_DEFAULT);
2504 debug3_f("received %s key %s", sshkey_type(key), fp);
2505 free(fp);
2506
2507 if (!key_accepted_by_hostkeyalgs(key)) {
2508 debug3_f("%s key not permitted by "
2509 "HostkeyAlgorithms", sshkey_ssh_name(key));
2510 continue;
2511 }
2512 /* Skip certs */
2513 if (sshkey_is_cert(key)) {
2514 debug3_f("%s key is a certificate; skipping",
2515 sshkey_ssh_name(key));
2516 continue;
2517 }
2518 /* Ensure keys are unique */
2519 for (i = 0; i < ctx->nkeys; i++) {
2520 if (sshkey_equal(key, ctx->keys[i])) {
2521 error_f("received duplicated %s host key",
2522 sshkey_ssh_name(key));
2523 goto out;
2524 }
2525 }
2526 /* Key is good, record it */
2527 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1,
2528 sizeof(*ctx->keys))) == NULL)
2529 fatal_f("recallocarray failed nkeys = %zu",
2530 ctx->nkeys);
2531 ctx->keys = tmp;
2532 ctx->keys[ctx->nkeys++] = key;
2533 key = NULL;
2534 }
2535
2536 if (ctx->nkeys == 0) {
2537 debug_f("server sent no hostkeys");
2538 goto out;
2539 }
2540
2541 if ((ctx->keys_match = calloc(ctx->nkeys,
2542 sizeof(*ctx->keys_match))) == NULL ||
2543 (ctx->keys_verified = calloc(ctx->nkeys,
2544 sizeof(*ctx->keys_verified))) == NULL)
2545 fatal_f("calloc failed");
2546
2547 get_hostfile_hostname_ipaddr(host,
2548 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
2549 options.port, &ctx->host_str,
2550 options.check_host_ip ? &ctx->ip_str : NULL);
2551
2552 /* Find which keys we already know about. */
2553 for (i = 0; i < options.num_user_hostfiles; i++) {
2554 debug_f("searching %s for %s / %s",
2555 options.user_hostfiles[i], ctx->host_str,
2556 ctx->ip_str ? ctx->ip_str : "(none)");
2557 if ((r = hostkeys_foreach(options.user_hostfiles[i],
2558 hostkeys_find, ctx, ctx->host_str, ctx->ip_str,
2559 HKF_WANT_PARSE_KEY, 0)) != 0) {
2560 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
2561 debug_f("hostkeys file %s does not exist",
2562 options.user_hostfiles[i]);
2563 continue;
2564 }
2565 error_fr(r, "hostkeys_foreach failed for %s",
2566 options.user_hostfiles[i]);
2567 goto out;
2568 }
2569 }
2570
2571 /* Figure out if we have any new keys to add */
2572 ctx->nnew = ctx->nincomplete = 0;
2573 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0);
2574 for (i = 0; i < ctx->nkeys; i++) {
2575 if (ctx->keys_match[i] == 0)
2576 ctx->nnew++;
2577 if ((ctx->keys_match[i] & want) != want)
2578 ctx->nincomplete++;
2579 }
2580
2581 debug3_f("%zu server keys: %zu new, %zu retained, "
2582 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew,
2583 ctx->nkeys - ctx->nnew - ctx->nincomplete,
2584 ctx->nincomplete, ctx->nold);
2585
2586 if (ctx->nnew == 0 && ctx->nold == 0) {
2587 debug_f("no new or deprecated keys from server");
2588 goto out;
2589 }
2590
2591 /* Various reasons why we cannot proceed with the update */
2592 if (ctx->complex_hostspec) {
2593 debug_f("CA/revocation marker, manual host list or wildcard "
2594 "host pattern found, skipping UserKnownHostsFile update");
2595 goto out;
2596 }
2597 if (ctx->other_name_seen) {
2598 debug_f("host key found matching a different name/address, "
2599 "skipping UserKnownHostsFile update");
2600 goto out;
2601 }
2602 /*
2603 * If removing keys, check whether they appear under different
2604 * names/addresses and refuse to proceed if they do. This avoids
2605 * cases such as hosts with multiple names becoming inconsistent
2606 * with regards to CheckHostIP entries.
2607 * XXX UpdateHostkeys=force to override this (and other) checks?
2608 */
2609 if (ctx->nold != 0) {
2610 if (check_old_keys_othernames(ctx) != 0)
2611 goto out; /* error already logged */
2612 if (ctx->old_key_seen) {
2613 debug_f("key(s) for %s%s%s exist under other names; "
2614 "skipping UserKnownHostsFile update",
2615 ctx->host_str, ctx->ip_str == NULL ? "" : ",",
2616 ctx->ip_str == NULL ? "" : ctx->ip_str);
2617 goto out;
2618 }
2619 }
2620
2621 if (ctx->nnew == 0) {
2622 /*
2623 * We have some keys to remove or fix matching for.
2624 * We can proceed to do this without requiring a fresh proof
2625 * from the server.
2626 */
2627 update_known_hosts(ctx);
2628 goto out;
2629 }
2630 /*
2631 * We have received previously-unseen keys from the server.
2632 * Ask the server to confirm ownership of the private halves.
2633 */
2634 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew);
2635 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2636 (r = sshpkt_put_cstring(ssh,
2637 "hostkeys-prove-00@openssh.com")) != 0 ||
2638 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
2639 fatal_fr(r, "prepare hostkeys-prove");
2640 if ((buf = sshbuf_new()) == NULL)
2641 fatal_f("sshbuf_new");
2642 for (i = 0; i < ctx->nkeys; i++) {
2643 if (ctx->keys_match[i])
2644 continue;
2645 sshbuf_reset(buf);
2646 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 ||
2647 (r = sshpkt_put_stringb(ssh, buf)) != 0)
2648 fatal_fr(r, "assemble hostkeys-prove");
2649 }
2650 if ((r = sshpkt_send(ssh)) != 0)
2651 fatal_fr(r, "send hostkeys-prove");
2652 client_register_global_confirm(
2653 client_global_hostkeys_prove_confirm, ctx);
2654 ctx = NULL; /* will be freed in callback */
2655 prove_sent = 1;
2656
2657 /* Success */
2658 out:
2659 hostkeys_update_ctx_free(ctx);
2660 sshkey_free(key);
2661 sshbuf_free(buf);
2662 if (!prove_sent) {
2663 /* UpdateHostkeys handling completed */
2664 hostkeys_update_complete = 1;
2665 client_repledge();
2666 }
2667 /*
2668 * NB. Return success for all cases. The server doesn't need to know
2669 * what the client does with its hosts file.
2670 */
2671 return 1;
2672 }
2673
2674 static int
client_input_global_request(int type,u_int32_t seq,struct ssh * ssh)2675 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
2676 {
2677 char *rtype;
2678 u_char want_reply;
2679 int r, success = 0;
2680
2681 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
2682 (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
2683 goto out;
2684 debug("client_input_global_request: rtype %s want_reply %d",
2685 rtype, want_reply);
2686 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
2687 success = client_input_hostkeys(ssh);
2688 if (want_reply) {
2689 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS :
2690 SSH2_MSG_REQUEST_FAILURE)) != 0 ||
2691 (r = sshpkt_send(ssh)) != 0 ||
2692 (r = ssh_packet_write_wait(ssh)) != 0)
2693 goto out;
2694 }
2695 r = 0;
2696 out:
2697 free(rtype);
2698 return r;
2699 }
2700
2701 static void
client_send_env(struct ssh * ssh,int id,const char * name,const char * val)2702 client_send_env(struct ssh *ssh, int id, const char *name, const char *val)
2703 {
2704 int r;
2705
2706 debug("channel %d: setting env %s = \"%s\"", id, name, val);
2707 channel_request_start(ssh, id, "env", 0);
2708 if ((r = sshpkt_put_cstring(ssh, name)) != 0 ||
2709 (r = sshpkt_put_cstring(ssh, val)) != 0 ||
2710 (r = sshpkt_send(ssh)) != 0)
2711 fatal_fr(r, "send setenv");
2712 }
2713
2714 void
client_session2_setup(struct ssh * ssh,int id,int want_tty,int want_subsystem,const char * term,struct termios * tiop,int in_fd,struct sshbuf * cmd,char ** env)2715 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
2716 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd,
2717 char **env)
2718 {
2719 size_t i, j, len;
2720 int matched, r;
2721 char *name, *val;
2722 Channel *c = NULL;
2723
2724 debug2_f("id %d", id);
2725
2726 if ((c = channel_lookup(ssh, id)) == NULL)
2727 fatal_f("channel %d: unknown channel", id);
2728
2729 ssh_packet_set_interactive(ssh, want_tty,
2730 options.ip_qos_interactive, options.ip_qos_bulk);
2731
2732 if (want_tty) {
2733 struct winsize ws;
2734
2735 /* Store window size in the packet. */
2736 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1)
2737 memset(&ws, 0, sizeof(ws));
2738
2739 channel_request_start(ssh, id, "pty-req", 1);
2740 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
2741 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : ""))
2742 != 0 ||
2743 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
2744 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
2745 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
2746 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0)
2747 fatal_fr(r, "build pty-req");
2748 if (tiop == NULL)
2749 tiop = get_saved_tio();
2750 ssh_tty_make_modes(ssh, -1, tiop);
2751 if ((r = sshpkt_send(ssh)) != 0)
2752 fatal_fr(r, "send pty-req");
2753 /* XXX wait for reply */
2754 c->client_tty = 1;
2755 }
2756
2757 /* Transfer any environment variables from client to server */
2758 if (options.num_send_env != 0 && env != NULL) {
2759 debug("Sending environment.");
2760 for (i = 0; env[i] != NULL; i++) {
2761 /* Split */
2762 name = xstrdup(env[i]);
2763 if ((val = strchr(name, '=')) == NULL) {
2764 free(name);
2765 continue;
2766 }
2767 *val++ = '\0';
2768
2769 matched = 0;
2770 for (j = 0; j < options.num_send_env; j++) {
2771 if (match_pattern(name, options.send_env[j])) {
2772 matched = 1;
2773 break;
2774 }
2775 }
2776 if (!matched) {
2777 debug3("Ignored env %s", name);
2778 free(name);
2779 continue;
2780 }
2781 client_send_env(ssh, id, name, val);
2782 free(name);
2783 }
2784 }
2785 for (i = 0; i < options.num_setenv; i++) {
2786 /* Split */
2787 name = xstrdup(options.setenv[i]);
2788 if ((val = strchr(name, '=')) == NULL) {
2789 free(name);
2790 continue;
2791 }
2792 *val++ = '\0';
2793 client_send_env(ssh, id, name, val);
2794 free(name);
2795 }
2796
2797 len = sshbuf_len(cmd);
2798 if (len > 0) {
2799 if (len > 900)
2800 len = 900;
2801 if (want_subsystem) {
2802 debug("Sending subsystem: %.*s",
2803 (int)len, (const u_char*)sshbuf_ptr(cmd));
2804 channel_request_start(ssh, id, "subsystem", 1);
2805 client_expect_confirm(ssh, id, "subsystem",
2806 CONFIRM_CLOSE);
2807 } else {
2808 debug("Sending command: %.*s",
2809 (int)len, (const u_char*)sshbuf_ptr(cmd));
2810 channel_request_start(ssh, id, "exec", 1);
2811 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
2812 }
2813 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 ||
2814 (r = sshpkt_send(ssh)) != 0)
2815 fatal_fr(r, "send command");
2816 } else {
2817 channel_request_start(ssh, id, "shell", 1);
2818 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
2819 if ((r = sshpkt_send(ssh)) != 0)
2820 fatal_fr(r, "send shell");
2821 }
2822
2823 session_setup_complete = 1;
2824 client_repledge();
2825 }
2826
2827 static void
client_init_dispatch(struct ssh * ssh)2828 client_init_dispatch(struct ssh *ssh)
2829 {
2830 ssh_dispatch_init(ssh, &dispatch_protocol_error);
2831
2832 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
2833 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
2834 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
2835 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
2836 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
2837 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
2838 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
2839 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
2840 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
2841 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
2842 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
2843 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
2844
2845 /* rekeying */
2846 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
2847
2848 /* global request reply messages */
2849 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
2850 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
2851 }
2852
2853 void
client_stop_mux(void)2854 client_stop_mux(void)
2855 {
2856 if (options.control_path != NULL && muxserver_sock != -1)
2857 unlink(options.control_path);
2858 /*
2859 * If we are in persist mode, or don't have a shell, signal that we
2860 * should close when all active channels are closed.
2861 */
2862 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) {
2863 session_closed = 1;
2864 setproctitle("[stopped mux]");
2865 }
2866 }
2867
2868 /* client specific fatal cleanup */
2869 void
cleanup_exit(int i)2870 cleanup_exit(int i)
2871 {
2872 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2873 if (options.control_path != NULL && muxserver_sock != -1)
2874 unlink(options.control_path);
2875 ssh_kill_proxy_command();
2876 _exit(i);
2877 }
2878