1 /* $OpenBSD: clientloop.c,v 1.408 2024/07/01 04:31:17 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 int connection_in; /* Connection to server (input). */
160 static int connection_out; /* Connection to server (output). */
161 static int need_rekeying; /* Set to non-zero if rekeying is requested. */
162 static int session_closed; /* In SSH2: login session closed. */
163 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */
164 static time_t server_alive_time; /* Time to do server_alive_check */
165 static int hostkeys_update_complete;
166 static int session_setup_complete;
167
168 static void client_init_dispatch(struct ssh *ssh);
169 int session_ident = -1;
170
171 /* Track escape per proto2 channel */
172 struct escape_filter_ctx {
173 int escape_pending;
174 int escape_char;
175 };
176
177 /* Context for channel confirmation replies */
178 struct channel_reply_ctx {
179 const char *request_type;
180 int id;
181 enum confirm_action action;
182 };
183
184 /* Global request success/failure callbacks */
185 /* XXX move to struct ssh? */
186 struct global_confirm {
187 TAILQ_ENTRY(global_confirm) entry;
188 global_confirm_cb *cb;
189 void *ctx;
190 int ref_count;
191 };
192 TAILQ_HEAD(global_confirms, global_confirm);
193 static struct global_confirms global_confirms =
194 TAILQ_HEAD_INITIALIZER(global_confirms);
195
196 static void quit_message(const char *fmt, ...)
197 __attribute__((__format__ (printf, 1, 2)));
198
199 static void
quit_message(const char * fmt,...)200 quit_message(const char *fmt, ...)
201 {
202 char *msg, *fmt2;
203 va_list args;
204 xasprintf(&fmt2, "%s\r\n", fmt);
205
206 va_start(args, fmt);
207 xvasprintf(&msg, fmt2, args);
208 va_end(args);
209
210 (void)atomicio(vwrite, STDERR_FILENO, msg, strlen(msg));
211 free(msg);
212 free(fmt2);
213
214 quit_pending = 1;
215 }
216
217 /*
218 * Signal handler for the window change signal (SIGWINCH). This just sets a
219 * flag indicating that the window has changed.
220 */
221 static void
window_change_handler(int sig)222 window_change_handler(int sig)
223 {
224 received_window_change_signal = 1;
225 }
226
227 /*
228 * Signal handler for signals that cause the program to terminate. These
229 * signals must be trapped to restore terminal modes.
230 */
231 static void
signal_handler(int sig)232 signal_handler(int sig)
233 {
234 received_signal = sig;
235 quit_pending = 1;
236 }
237
238 /*
239 * Sets control_persist_exit_time to the absolute time when the
240 * backgrounded control master should exit due to expiry of the
241 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded
242 * control master process, or if there is no ControlPersist timeout.
243 */
244 static void
set_control_persist_exit_time(struct ssh * ssh)245 set_control_persist_exit_time(struct ssh *ssh)
246 {
247 if (muxserver_sock == -1 || !options.control_persist
248 || options.control_persist_timeout == 0) {
249 /* not using a ControlPersist timeout */
250 control_persist_exit_time = 0;
251 } else if (channel_still_open(ssh)) {
252 /* some client connections are still open */
253 if (control_persist_exit_time > 0)
254 debug2_f("cancel scheduled exit");
255 control_persist_exit_time = 0;
256 } else if (control_persist_exit_time <= 0) {
257 /* a client connection has recently closed */
258 control_persist_exit_time = monotime() +
259 (time_t)options.control_persist_timeout;
260 debug2_f("schedule exit in %d seconds",
261 options.control_persist_timeout);
262 }
263 /* else we are already counting down to the timeout */
264 }
265
266 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
267 static int
client_x11_display_valid(const char * display)268 client_x11_display_valid(const char *display)
269 {
270 size_t i, dlen;
271
272 if (display == NULL)
273 return 0;
274
275 dlen = strlen(display);
276 for (i = 0; i < dlen; i++) {
277 if (!isalnum((u_char)display[i]) &&
278 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
279 debug("Invalid character '%c' in DISPLAY", display[i]);
280 return 0;
281 }
282 }
283 return 1;
284 }
285
286 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
287 #define X11_TIMEOUT_SLACK 60
288 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)289 client_x11_get_proto(struct ssh *ssh, const char *display,
290 const char *xauth_path, u_int trusted, u_int timeout,
291 char **_proto, char **_data)
292 {
293 char *cmd, line[512], xdisplay[512];
294 char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
295 static char proto[512], data[512];
296 FILE *f;
297 int got_data = 0, generated = 0, do_unlink = 0, r;
298 struct stat st;
299 u_int now, x11_timeout_real;
300
301 *_proto = proto;
302 *_data = data;
303 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';
304
305 if (!client_x11_display_valid(display)) {
306 if (display != NULL)
307 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
308 display);
309 return -1;
310 }
311 if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
312 debug("No xauth program.");
313 xauth_path = NULL;
314 }
315
316 if (xauth_path != NULL) {
317 /*
318 * Handle FamilyLocal case where $DISPLAY does
319 * not match an authorization entry. For this we
320 * just try "xauth list unix:displaynum.screennum".
321 * XXX: "localhost" match to determine FamilyLocal
322 * is not perfect.
323 */
324 if (strncmp(display, "localhost:", 10) == 0) {
325 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
326 display + 10)) < 0 ||
327 (size_t)r >= sizeof(xdisplay)) {
328 error_f("display name too long");
329 return -1;
330 }
331 display = xdisplay;
332 }
333 if (trusted == 0) {
334 /*
335 * Generate an untrusted X11 auth cookie.
336 *
337 * The authentication cookie should briefly outlive
338 * ssh's willingness to forward X11 connections to
339 * avoid nasty fail-open behaviour in the X server.
340 */
341 mktemp_proto(xauthdir, sizeof(xauthdir));
342 if (mkdtemp(xauthdir) == NULL) {
343 error_f("mkdtemp: %s", strerror(errno));
344 return -1;
345 }
346 do_unlink = 1;
347 if ((r = snprintf(xauthfile, sizeof(xauthfile),
348 "%s/xauthfile", xauthdir)) < 0 ||
349 (size_t)r >= sizeof(xauthfile)) {
350 error_f("xauthfile path too long");
351 rmdir(xauthdir);
352 return -1;
353 }
354
355 if (timeout == 0) {
356 /* auth doesn't time out */
357 xasprintf(&cmd, "%s -f %s generate %s %s "
358 "untrusted 2>%s",
359 xauth_path, xauthfile, display,
360 SSH_X11_PROTO, _PATH_DEVNULL);
361 } else {
362 /* Add some slack to requested expiry */
363 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK)
364 x11_timeout_real = timeout +
365 X11_TIMEOUT_SLACK;
366 else {
367 /* Don't overflow on long timeouts */
368 x11_timeout_real = UINT_MAX;
369 }
370 xasprintf(&cmd, "%s -f %s generate %s %s "
371 "untrusted timeout %u 2>%s",
372 xauth_path, xauthfile, display,
373 SSH_X11_PROTO, x11_timeout_real,
374 _PATH_DEVNULL);
375 }
376 debug2_f("xauth command: %s", cmd);
377
378 if (timeout != 0 && x11_refuse_time == 0) {
379 now = monotime() + 1;
380 if (SSH_TIME_T_MAX - timeout < now)
381 x11_refuse_time = SSH_TIME_T_MAX;
382 else
383 x11_refuse_time = now + timeout;
384 channel_set_x11_refuse_time(ssh,
385 x11_refuse_time);
386 }
387 if (system(cmd) == 0)
388 generated = 1;
389 free(cmd);
390 }
391
392 /*
393 * When in untrusted mode, we read the cookie only if it was
394 * successfully generated as an untrusted one in the step
395 * above.
396 */
397 if (trusted || generated) {
398 xasprintf(&cmd,
399 "%s %s%s list %s 2>" _PATH_DEVNULL,
400 xauth_path,
401 generated ? "-f " : "" ,
402 generated ? xauthfile : "",
403 display);
404 debug2("x11_get_proto: %s", cmd);
405 f = popen(cmd, "r");
406 if (f && fgets(line, sizeof(line), f) &&
407 sscanf(line, "%*s %511s %511s", proto, data) == 2)
408 got_data = 1;
409 if (f)
410 pclose(f);
411 free(cmd);
412 }
413 }
414
415 if (do_unlink) {
416 unlink(xauthfile);
417 rmdir(xauthdir);
418 }
419
420 /* Don't fall back to fake X11 data for untrusted forwarding */
421 if (!trusted && !got_data) {
422 error("Warning: untrusted X11 forwarding setup failed: "
423 "xauth key data not generated");
424 return -1;
425 }
426
427 /*
428 * If we didn't get authentication data, just make up some
429 * data. The forwarding code will check the validity of the
430 * response anyway, and substitute this data. The X11
431 * server, however, will ignore this fake data and use
432 * whatever authentication mechanisms it was using otherwise
433 * for the local connection.
434 */
435 if (!got_data) {
436 u_int8_t rnd[16];
437 u_int i;
438
439 logit("Warning: No xauth data; "
440 "using fake authentication data for X11 forwarding.");
441 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
442 arc4random_buf(rnd, sizeof(rnd));
443 for (i = 0; i < sizeof(rnd); i++) {
444 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
445 rnd[i]);
446 }
447 }
448
449 return 0;
450 }
451
452 /*
453 * Checks if the client window has changed, and sends a packet about it to
454 * the server if so. The actual change is detected elsewhere (by a software
455 * interrupt on Unix); this just checks the flag and sends a message if
456 * appropriate.
457 */
458
459 static void
client_check_window_change(struct ssh * ssh)460 client_check_window_change(struct ssh *ssh)
461 {
462 if (!received_window_change_signal)
463 return;
464 received_window_change_signal = 0;
465 debug2_f("changed");
466 channel_send_window_changes(ssh);
467 }
468
469 static int
client_global_request_reply(int type,u_int32_t seq,struct ssh * ssh)470 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
471 {
472 struct global_confirm *gc;
473
474 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
475 return 0;
476 if (gc->cb != NULL)
477 gc->cb(ssh, type, seq, gc->ctx);
478 if (--gc->ref_count <= 0) {
479 TAILQ_REMOVE(&global_confirms, gc, entry);
480 freezero(gc, sizeof(*gc));
481 }
482
483 ssh_packet_set_alive_timeouts(ssh, 0);
484 return 0;
485 }
486
487 static void
schedule_server_alive_check(void)488 schedule_server_alive_check(void)
489 {
490 if (options.server_alive_interval > 0)
491 server_alive_time = monotime() + options.server_alive_interval;
492 }
493
494 static void
server_alive_check(struct ssh * ssh)495 server_alive_check(struct ssh *ssh)
496 {
497 int r;
498
499 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) {
500 logit("Timeout, server %s not responding.", host);
501 cleanup_exit(255);
502 }
503 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
504 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 ||
505 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */
506 (r = sshpkt_send(ssh)) != 0)
507 fatal_fr(r, "send packet");
508 /* Insert an empty placeholder to maintain ordering */
509 client_register_global_confirm(NULL, NULL);
510 schedule_server_alive_check();
511 }
512
513 /* Try to send a dummy keystroke */
514 static int
send_chaff(struct ssh * ssh)515 send_chaff(struct ssh *ssh)
516 {
517 int r;
518
519 if (ssh->kex == NULL || (ssh->kex->flags & KEX_HAS_PING) == 0)
520 return 0;
521 /* XXX probabilistically send chaff? */
522 /*
523 * a SSH2_MSG_CHANNEL_DATA payload is 9 bytes:
524 * 4 bytes channel ID + 4 bytes string length + 1 byte string data
525 * simulate that here.
526 */
527 if ((r = sshpkt_start(ssh, SSH2_MSG_PING)) != 0 ||
528 (r = sshpkt_put_cstring(ssh, "PING!")) != 0 ||
529 (r = sshpkt_send(ssh)) != 0)
530 fatal_fr(r, "send packet");
531 return 1;
532 }
533
534 /* Sets the next interval to send a keystroke or chaff packet */
535 static void
set_next_interval(const struct timespec * now,struct timespec * next_interval,u_int interval_ms,int starting)536 set_next_interval(const struct timespec *now, struct timespec *next_interval,
537 u_int interval_ms, int starting)
538 {
539 struct timespec tmp;
540 long long interval_ns, fuzz_ns;
541 static long long rate_fuzz;
542
543 interval_ns = interval_ms * (1000LL * 1000);
544 fuzz_ns = (interval_ns * SSH_KEYSTROKE_TIMING_FUZZ) / 100;
545 /* Center fuzz around requested interval */
546 if (fuzz_ns > INT_MAX)
547 fuzz_ns = INT_MAX;
548 if (fuzz_ns > interval_ns) {
549 /* Shouldn't happen */
550 fatal_f("internal error: fuzz %u%% %lldns > interval %lldns",
551 SSH_KEYSTROKE_TIMING_FUZZ, fuzz_ns, interval_ns);
552 }
553 /*
554 * Randomise the keystroke/chaff intervals in two ways:
555 * 1. Each interval has some random jitter applied to make the
556 * interval-to-interval time unpredictable.
557 * 2. The overall interval rate is also randomly perturbed for each
558 * chaffing session to make the average rate unpredictable.
559 */
560 if (starting)
561 rate_fuzz = arc4random_uniform(fuzz_ns);
562 interval_ns -= fuzz_ns;
563 interval_ns += arc4random_uniform(fuzz_ns) + rate_fuzz;
564
565 tmp.tv_sec = interval_ns / (1000 * 1000 * 1000);
566 tmp.tv_nsec = interval_ns % (1000 * 1000 * 1000);
567
568 timespecadd(now, &tmp, next_interval);
569 }
570
571 /*
572 * Performs keystroke timing obfuscation. Returns non-zero if the
573 * output fd should be polled.
574 */
575 static int
obfuscate_keystroke_timing(struct ssh * ssh,struct timespec * timeout,int channel_did_enqueue)576 obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout,
577 int channel_did_enqueue)
578 {
579 static int active;
580 static struct timespec next_interval, chaff_until;
581 struct timespec now, tmp;
582 int just_started = 0, had_keystroke = 0;
583 static unsigned long long nchaff;
584 char *stop_reason = NULL;
585 long long n;
586
587 monotime_ts(&now);
588
589 if (options.obscure_keystroke_timing_interval <= 0)
590 return 1; /* disabled in config */
591
592 if (!channel_tty_open(ssh) || quit_pending) {
593 /* Stop if no channels left of we're waiting for one to close */
594 stop_reason = "no active channels";
595 } else if (ssh_packet_is_rekeying(ssh)) {
596 /* Stop if we're rekeying */
597 stop_reason = "rekeying started";
598 } else if (!ssh_packet_interactive_data_to_write(ssh) &&
599 ssh_packet_have_data_to_write(ssh)) {
600 /* Stop if the output buffer has more than a few keystrokes */
601 stop_reason = "output buffer filling";
602 } else if (active && channel_did_enqueue &&
603 ssh_packet_have_data_to_write(ssh)) {
604 /* Still in active mode and have a keystroke queued. */
605 had_keystroke = 1;
606 } else if (active) {
607 if (timespeccmp(&now, &chaff_until, >=)) {
608 /* Stop if there have been no keystrokes for a while */
609 stop_reason = "chaff time expired";
610 } else if (timespeccmp(&now, &next_interval, >=) &&
611 !ssh_packet_have_data_to_write(ssh)) {
612 /* If due to send but have no data, 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;
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 client_init_dispatch(ssh);
1502
1503 /*
1504 * Set signal handlers, (e.g. to restore non-blocking mode)
1505 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
1506 */
1507 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN)
1508 ssh_signal(SIGHUP, signal_handler);
1509 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN)
1510 ssh_signal(SIGINT, signal_handler);
1511 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN)
1512 ssh_signal(SIGQUIT, signal_handler);
1513 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN)
1514 ssh_signal(SIGTERM, signal_handler);
1515 ssh_signal(SIGWINCH, window_change_handler);
1516
1517 if (have_pty)
1518 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1519
1520 if (session_ident != -1) {
1521 if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
1522 channel_register_filter(ssh, session_ident,
1523 client_simple_escape_filter, NULL,
1524 client_filter_cleanup,
1525 client_new_escape_filter_ctx(
1526 escape_char_arg));
1527 }
1528 channel_register_cleanup(ssh, session_ident,
1529 client_channel_closed, 0);
1530 }
1531
1532 schedule_server_alive_check();
1533
1534 if (sigemptyset(&bsigset) == -1 ||
1535 sigaddset(&bsigset, SIGHUP) == -1 ||
1536 sigaddset(&bsigset, SIGINT) == -1 ||
1537 sigaddset(&bsigset, SIGQUIT) == -1 ||
1538 sigaddset(&bsigset, SIGTERM) == -1)
1539 error_f("bsigset setup: %s", strerror(errno));
1540
1541 /* Main loop of the client for the interactive session mode. */
1542 while (!quit_pending) {
1543 channel_did_enqueue = 0;
1544
1545 /* Process buffered packets sent by the server. */
1546 client_process_buffered_input_packets(ssh);
1547
1548 if (session_closed && !channel_still_open(ssh))
1549 break;
1550
1551 if (ssh_packet_is_rekeying(ssh)) {
1552 debug("rekeying in progress");
1553 } else if (need_rekeying) {
1554 /* manual rekey request */
1555 debug("need rekeying");
1556 if ((r = kex_start_rekex(ssh)) != 0)
1557 fatal_fr(r, "kex_start_rekex");
1558 need_rekeying = 0;
1559 } else {
1560 /*
1561 * Make packets from buffered channel data, and
1562 * enqueue them for sending to the server.
1563 */
1564 if (ssh_packet_not_very_much_data_to_write(ssh))
1565 channel_did_enqueue = channel_output_poll(ssh);
1566
1567 /*
1568 * Check if the window size has changed, and buffer a
1569 * message about it to the server if so.
1570 */
1571 client_check_window_change(ssh);
1572 }
1573 /*
1574 * Wait until we have something to do (something becomes
1575 * available on one of the descriptors).
1576 */
1577 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1)
1578 error_f("bsigset sigprocmask: %s", strerror(errno));
1579 if (quit_pending)
1580 break;
1581 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc,
1582 &npfd_active, channel_did_enqueue, &osigset,
1583 &conn_in_ready, &conn_out_ready);
1584 if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1)
1585 error_f("osigset sigprocmask: %s", strerror(errno));
1586
1587 if (quit_pending)
1588 break;
1589
1590 /* Do channel operations. */
1591 channel_after_poll(ssh, pfd, npfd_active);
1592
1593 /* Buffer input from the connection. */
1594 if (conn_in_ready)
1595 client_process_net_input(ssh);
1596
1597 if (quit_pending)
1598 break;
1599
1600 /* A timeout may have triggered rekeying */
1601 if ((r = ssh_packet_check_rekey(ssh)) != 0)
1602 fatal_fr(r, "cannot start rekeying");
1603
1604 /*
1605 * Send as much buffered packet data as possible to the
1606 * sender.
1607 */
1608 if (conn_out_ready) {
1609 if ((r = ssh_packet_write_poll(ssh)) != 0) {
1610 sshpkt_fatal(ssh, r,
1611 "%s: ssh_packet_write_poll", __func__);
1612 }
1613 }
1614
1615 /*
1616 * If we are a backgrounded control master, and the
1617 * timeout has expired without any active client
1618 * connections, then quit.
1619 */
1620 if (control_persist_exit_time > 0) {
1621 if (monotime() >= control_persist_exit_time) {
1622 debug("ControlPersist timeout expired");
1623 break;
1624 }
1625 }
1626 }
1627 free(pfd);
1628
1629 /* Terminate the session. */
1630
1631 /*
1632 * In interactive mode (with pseudo tty) display a message indicating
1633 * that the connection has been closed.
1634 */
1635 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO)
1636 quit_message("Connection to %s closed.", host);
1637
1638
1639 /* Stop watching for window change. */
1640 ssh_signal(SIGWINCH, SIG_DFL);
1641
1642 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
1643 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 ||
1644 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 ||
1645 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */
1646 (r = sshpkt_send(ssh)) != 0 ||
1647 (r = ssh_packet_write_wait(ssh)) != 0)
1648 fatal_fr(r, "send disconnect");
1649
1650 channel_free_all(ssh);
1651
1652 if (have_pty)
1653 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1654
1655 /*
1656 * If there was no shell or command requested, there will be no remote
1657 * exit status to be returned. In that case, clear error code if the
1658 * connection was deliberately terminated at this end.
1659 */
1660 if (options.session_type == SESSION_TYPE_NONE &&
1661 received_signal == SIGTERM) {
1662 received_signal = 0;
1663 exit_status = 0;
1664 }
1665
1666 if (received_signal) {
1667 verbose("Killed by signal %d.", (int) received_signal);
1668 cleanup_exit(255);
1669 }
1670
1671 /* Report bytes transferred, and transfer rates. */
1672 total_time = monotime_double() - start_time;
1673 ssh_packet_get_bytes(ssh, &ibytes, &obytes);
1674 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
1675 (unsigned long long)obytes, (unsigned long long)ibytes, total_time);
1676 if (total_time > 0)
1677 verbose("Bytes per second: sent %.1f, received %.1f",
1678 obytes / total_time, ibytes / total_time);
1679 /* Return the exit status of the program. */
1680 debug("Exit status %d", exit_status);
1681 return exit_status;
1682 }
1683
1684 /*********/
1685
1686 static Channel *
client_request_forwarded_tcpip(struct ssh * ssh,const char * request_type,int rchan,u_int rwindow,u_int rmaxpack)1687 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
1688 int rchan, u_int rwindow, u_int rmaxpack)
1689 {
1690 Channel *c = NULL;
1691 struct sshbuf *b = NULL;
1692 char *listen_address, *originator_address;
1693 u_int listen_port, originator_port;
1694 int r;
1695
1696 /* Get rest of the packet */
1697 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 ||
1698 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 ||
1699 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 ||
1700 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
1701 (r = sshpkt_get_end(ssh)) != 0)
1702 fatal_fr(r, "parse packet");
1703
1704 debug_f("listen %s port %d, originator %s port %d",
1705 listen_address, listen_port, originator_address, originator_port);
1706
1707 if (listen_port > 0xffff)
1708 error_f("invalid listen port");
1709 else if (originator_port > 0xffff)
1710 error_f("invalid originator port");
1711 else {
1712 c = channel_connect_by_listen_address(ssh,
1713 listen_address, listen_port, "forwarded-tcpip",
1714 originator_address);
1715 }
1716
1717 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1718 if ((b = sshbuf_new()) == NULL) {
1719 error_f("alloc reply");
1720 goto out;
1721 }
1722 /* reconstruct and send to muxclient */
1723 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
1724 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1725 (r = sshbuf_put_cstring(b, request_type)) != 0 ||
1726 (r = sshbuf_put_u32(b, rchan)) != 0 ||
1727 (r = sshbuf_put_u32(b, rwindow)) != 0 ||
1728 (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
1729 (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
1730 (r = sshbuf_put_u32(b, listen_port)) != 0 ||
1731 (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
1732 (r = sshbuf_put_u32(b, originator_port)) != 0 ||
1733 (r = sshbuf_put_stringb(c->output, b)) != 0) {
1734 error_fr(r, "compose for muxclient");
1735 goto out;
1736 }
1737 }
1738
1739 out:
1740 sshbuf_free(b);
1741 free(originator_address);
1742 free(listen_address);
1743 return c;
1744 }
1745
1746 static Channel *
client_request_forwarded_streamlocal(struct ssh * ssh,const char * request_type,int rchan)1747 client_request_forwarded_streamlocal(struct ssh *ssh,
1748 const char *request_type, int rchan)
1749 {
1750 Channel *c = NULL;
1751 char *listen_path;
1752 int r;
1753
1754 /* Get the remote path. */
1755 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 ||
1756 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */
1757 (r = sshpkt_get_end(ssh)) != 0)
1758 fatal_fr(r, "parse packet");
1759
1760 debug_f("request: %s", listen_path);
1761
1762 c = channel_connect_by_listen_path(ssh, listen_path,
1763 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
1764 free(listen_path);
1765 return c;
1766 }
1767
1768 static Channel *
client_request_x11(struct ssh * ssh,const char * request_type,int rchan)1769 client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
1770 {
1771 Channel *c = NULL;
1772 char *originator;
1773 u_int originator_port;
1774 int r, sock;
1775
1776 if (!options.forward_x11) {
1777 error("Warning: ssh server tried X11 forwarding.");
1778 error("Warning: this is probably a break-in attempt by a "
1779 "malicious server.");
1780 return NULL;
1781 }
1782 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) {
1783 verbose("Rejected X11 connection after ForwardX11Timeout "
1784 "expired");
1785 return NULL;
1786 }
1787 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
1788 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
1789 (r = sshpkt_get_end(ssh)) != 0)
1790 fatal_fr(r, "parse packet");
1791 /* XXX check permission */
1792 /* XXX range check originator port? */
1793 debug("client_request_x11: request from %s %u", originator,
1794 originator_port);
1795 free(originator);
1796 sock = x11_connect_display(ssh);
1797 if (sock < 0)
1798 return NULL;
1799 c = channel_new(ssh, "x11-connection",
1800 SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1801 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1802 c->force_drain = 1;
1803 return c;
1804 }
1805
1806 static Channel *
client_request_agent(struct ssh * ssh,const char * request_type,int rchan)1807 client_request_agent(struct ssh *ssh, const char *request_type, int rchan)
1808 {
1809 Channel *c = NULL;
1810 int r, sock;
1811
1812 if (!options.forward_agent) {
1813 error("Warning: ssh server tried agent forwarding.");
1814 error("Warning: this is probably a break-in attempt by a "
1815 "malicious server.");
1816 return NULL;
1817 }
1818 if (forward_agent_sock_path == NULL) {
1819 r = ssh_get_authentication_socket(&sock);
1820 } else {
1821 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock);
1822 }
1823 if (r != 0) {
1824 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1825 debug_fr(r, "ssh_get_authentication_socket");
1826 return NULL;
1827 }
1828 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey,
1829 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0)
1830 debug_f("bound agent to hostkey");
1831 else
1832 debug2_fr(r, "ssh_agent_bind_hostkey");
1833
1834 c = channel_new(ssh, "agent-connection",
1835 SSH_CHANNEL_OPEN, sock, sock, -1,
1836 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
1837 "authentication agent connection", 1);
1838 c->force_drain = 1;
1839 return c;
1840 }
1841
1842 char *
client_request_tun_fwd(struct ssh * ssh,int tun_mode,int local_tun,int remote_tun,channel_open_fn * cb,void * cbctx)1843 client_request_tun_fwd(struct ssh *ssh, int tun_mode,
1844 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx)
1845 {
1846 Channel *c;
1847 int r, fd;
1848 char *ifname = NULL;
1849
1850 if (tun_mode == SSH_TUNMODE_NO)
1851 return 0;
1852
1853 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);
1854
1855 /* Open local tunnel device */
1856 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) {
1857 error("Tunnel device open failed.");
1858 return NULL;
1859 }
1860 debug("Tunnel forwarding using interface %s", ifname);
1861
1862 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1,
1863 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1864 c->datagram = 1;
1865
1866 #if defined(SSH_TUN_FILTER)
1867 if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1868 channel_register_filter(ssh, c->self, sys_tun_infilter,
1869 sys_tun_outfilter, NULL, NULL);
1870 #endif
1871
1872 if (cb != NULL)
1873 channel_register_open_confirm(ssh, c->self, cb, cbctx);
1874
1875 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1876 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 ||
1877 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
1878 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 ||
1879 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
1880 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 ||
1881 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 ||
1882 (r = sshpkt_send(ssh)) != 0)
1883 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
1884
1885 return ifname;
1886 }
1887
1888 /* XXXX move to generic input handler */
1889 static int
client_input_channel_open(int type,u_int32_t seq,struct ssh * ssh)1890 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
1891 {
1892 Channel *c = NULL;
1893 char *ctype = NULL;
1894 int r;
1895 u_int rchan;
1896 size_t len;
1897 u_int rmaxpack, rwindow;
1898
1899 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 ||
1900 (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
1901 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
1902 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
1903 goto out;
1904
1905 debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
1906 ctype, rchan, rwindow, rmaxpack);
1907
1908 if (strcmp(ctype, "forwarded-tcpip") == 0) {
1909 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow,
1910 rmaxpack);
1911 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
1912 c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
1913 } else if (strcmp(ctype, "x11") == 0) {
1914 c = client_request_x11(ssh, ctype, rchan);
1915 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
1916 c = client_request_agent(ssh, ctype, rchan);
1917 }
1918 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1919 debug3("proxied to downstream: %s", ctype);
1920 } else if (c != NULL) {
1921 debug("confirm %s", ctype);
1922 c->remote_id = rchan;
1923 c->have_remote_id = 1;
1924 c->remote_window = rwindow;
1925 c->remote_maxpacket = rmaxpack;
1926 if (c->type != SSH_CHANNEL_CONNECTING) {
1927 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
1928 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
1929 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
1930 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
1931 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
1932 (r = sshpkt_send(ssh)) != 0)
1933 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
1934 }
1935 } else {
1936 debug("failure %s", ctype);
1937 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
1938 (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
1939 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 ||
1940 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 ||
1941 (r = sshpkt_put_cstring(ssh, "")) != 0 ||
1942 (r = sshpkt_send(ssh)) != 0)
1943 sshpkt_fatal(ssh, r, "%s: send failure", __func__);
1944 }
1945 r = 0;
1946 out:
1947 free(ctype);
1948 return r;
1949 }
1950
1951 static int
client_input_channel_req(int type,u_int32_t seq,struct ssh * ssh)1952 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
1953 {
1954 Channel *c = NULL;
1955 char *rtype = NULL;
1956 u_char reply;
1957 u_int id, exitval;
1958 int r, success = 0;
1959
1960 if ((r = sshpkt_get_u32(ssh, &id)) != 0)
1961 return r;
1962 if (id <= INT_MAX)
1963 c = channel_lookup(ssh, id);
1964 if (channel_proxy_upstream(c, type, seq, ssh))
1965 return 0;
1966 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
1967 (r = sshpkt_get_u8(ssh, &reply)) != 0)
1968 goto out;
1969
1970 debug("client_input_channel_req: channel %u rtype %s reply %d",
1971 id, rtype, reply);
1972
1973 if (c == NULL) {
1974 error("client_input_channel_req: channel %d: "
1975 "unknown channel", id);
1976 } else if (strcmp(rtype, "eow@openssh.com") == 0) {
1977 if ((r = sshpkt_get_end(ssh)) != 0)
1978 goto out;
1979 chan_rcvd_eow(ssh, c);
1980 } else if (strcmp(rtype, "exit-status") == 0) {
1981 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0)
1982 goto out;
1983 if (c->ctl_chan != -1) {
1984 mux_exit_message(ssh, c, exitval);
1985 success = 1;
1986 } else if ((int)id == session_ident) {
1987 /* Record exit value of local session */
1988 success = 1;
1989 exit_status = exitval;
1990 } else {
1991 /* Probably for a mux channel that has already closed */
1992 debug_f("no sink for exit-status on channel %d",
1993 id);
1994 }
1995 if ((r = sshpkt_get_end(ssh)) != 0)
1996 goto out;
1997 }
1998 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
1999 if (!c->have_remote_id)
2000 fatal_f("channel %d: no remote_id", c->self);
2001 if ((r = sshpkt_start(ssh, success ?
2002 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
2003 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
2004 (r = sshpkt_send(ssh)) != 0)
2005 sshpkt_fatal(ssh, r, "%s: send failure", __func__);
2006 }
2007 r = 0;
2008 out:
2009 free(rtype);
2010 return r;
2011 }
2012
2013 struct hostkeys_update_ctx {
2014 /* The hostname and (optionally) IP address string for the server */
2015 char *host_str, *ip_str;
2016
2017 /*
2018 * Keys received from the server and a flag for each indicating
2019 * whether they already exist in known_hosts.
2020 * keys_match is filled in by hostkeys_find() and later (for new
2021 * keys) by client_global_hostkeys_prove_confirm().
2022 */
2023 struct sshkey **keys;
2024 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */
2025 int *keys_verified; /* flag for new keys verified by server */
2026 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */
2027
2028 /*
2029 * Keys that are in known_hosts, but were not present in the update
2030 * from the server (i.e. scheduled to be deleted).
2031 * Filled in by hostkeys_find().
2032 */
2033 struct sshkey **old_keys;
2034 size_t nold;
2035
2036 /* Various special cases. */
2037 int complex_hostspec; /* wildcard or manual pattern-list host name */
2038 int ca_available; /* saw CA key for this host */
2039 int old_key_seen; /* saw old key with other name/addr */
2040 int other_name_seen; /* saw key with other name/addr */
2041 };
2042
2043 static void
hostkeys_update_ctx_free(struct hostkeys_update_ctx * ctx)2044 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
2045 {
2046 size_t i;
2047
2048 if (ctx == NULL)
2049 return;
2050 for (i = 0; i < ctx->nkeys; i++)
2051 sshkey_free(ctx->keys[i]);
2052 free(ctx->keys);
2053 free(ctx->keys_match);
2054 free(ctx->keys_verified);
2055 for (i = 0; i < ctx->nold; i++)
2056 sshkey_free(ctx->old_keys[i]);
2057 free(ctx->old_keys);
2058 free(ctx->host_str);
2059 free(ctx->ip_str);
2060 free(ctx);
2061 }
2062
2063 /*
2064 * Returns non-zero if a known_hosts hostname list is not of a form that
2065 * can be handled by UpdateHostkeys. These include wildcard hostnames and
2066 * hostnames lists that do not follow the form host[,ip].
2067 */
2068 static int
hostspec_is_complex(const char * hosts)2069 hostspec_is_complex(const char *hosts)
2070 {
2071 char *cp;
2072
2073 /* wildcard */
2074 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL)
2075 return 1;
2076 /* single host/ip = ok */
2077 if ((cp = strchr(hosts, ',')) == NULL)
2078 return 0;
2079 /* more than two entries on the line */
2080 if (strchr(cp + 1, ',') != NULL)
2081 return 1;
2082 /* XXX maybe parse cp+1 and ensure it is an IP? */
2083 return 0;
2084 }
2085
2086 /* callback to search for ctx->keys in known_hosts */
2087 static int
hostkeys_find(struct hostkey_foreach_line * l,void * _ctx)2088 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
2089 {
2090 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2091 size_t i;
2092 struct sshkey **tmp;
2093
2094 if (l->key == NULL)
2095 return 0;
2096 if (l->status != HKF_STATUS_MATCHED) {
2097 /* Record if one of the keys appears on a non-matching line */
2098 for (i = 0; i < ctx->nkeys; i++) {
2099 if (sshkey_equal(l->key, ctx->keys[i])) {
2100 ctx->other_name_seen = 1;
2101 debug3_f("found %s key under different "
2102 "name/addr at %s:%ld",
2103 sshkey_ssh_name(ctx->keys[i]),
2104 l->path, l->linenum);
2105 return 0;
2106 }
2107 }
2108 return 0;
2109 }
2110 /* Don't proceed if revocation or CA markers are present */
2111 /* XXX relax this */
2112 if (l->marker != MRK_NONE) {
2113 debug3_f("hostkeys file %s:%ld has CA/revocation marker",
2114 l->path, l->linenum);
2115 ctx->complex_hostspec = 1;
2116 return 0;
2117 }
2118
2119 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */
2120 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) {
2121 if ((l->match & HKF_MATCH_HOST) == 0) {
2122 /* Record if address matched a different hostname. */
2123 ctx->other_name_seen = 1;
2124 debug3_f("found address %s against different hostname "
2125 "at %s:%ld", ctx->ip_str, l->path, l->linenum);
2126 return 0;
2127 } else if ((l->match & HKF_MATCH_IP) == 0) {
2128 /* Record if hostname matched a different address. */
2129 ctx->other_name_seen = 1;
2130 debug3_f("found hostname %s against different address "
2131 "at %s:%ld", ctx->host_str, l->path, l->linenum);
2132 }
2133 }
2134
2135 /*
2136 * UpdateHostkeys is skipped for wildcard host names and hostnames
2137 * that contain more than two entries (ssh never writes these).
2138 */
2139 if (hostspec_is_complex(l->hosts)) {
2140 debug3_f("hostkeys file %s:%ld complex host specification",
2141 l->path, l->linenum);
2142 ctx->complex_hostspec = 1;
2143 return 0;
2144 }
2145
2146 /* Mark off keys we've already seen for this host */
2147 for (i = 0; i < ctx->nkeys; i++) {
2148 if (!sshkey_equal(l->key, ctx->keys[i]))
2149 continue;
2150 debug3_f("found %s key at %s:%ld",
2151 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
2152 ctx->keys_match[i] |= l->match;
2153 return 0;
2154 }
2155 /* This line contained a key that not offered by the server */
2156 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key),
2157 l->path, l->linenum);
2158 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1,
2159 sizeof(*ctx->old_keys))) == NULL)
2160 fatal_f("recallocarray failed nold = %zu", ctx->nold);
2161 ctx->old_keys = tmp;
2162 ctx->old_keys[ctx->nold++] = l->key;
2163 l->key = NULL;
2164
2165 return 0;
2166 }
2167
2168 /* callback to search for ctx->old_keys in known_hosts under other names */
2169 static int
hostkeys_check_old(struct hostkey_foreach_line * l,void * _ctx)2170 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx)
2171 {
2172 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2173 size_t i;
2174 int hashed;
2175
2176 /* only care about lines that *don't* match the active host spec */
2177 if (l->status == HKF_STATUS_MATCHED || l->key == NULL)
2178 return 0;
2179
2180 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED);
2181 for (i = 0; i < ctx->nold; i++) {
2182 if (!sshkey_equal(l->key, ctx->old_keys[i]))
2183 continue;
2184 debug3_f("found deprecated %s key at %s:%ld as %s",
2185 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum,
2186 hashed ? "[HASHED]" : l->hosts);
2187 ctx->old_key_seen = 1;
2188 break;
2189 }
2190 return 0;
2191 }
2192
2193 /*
2194 * Check known_hosts files for deprecated keys under other names. Returns 0
2195 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys
2196 * exist under names other than the active hostname/IP.
2197 */
2198 static int
check_old_keys_othernames(struct hostkeys_update_ctx * ctx)2199 check_old_keys_othernames(struct hostkeys_update_ctx *ctx)
2200 {
2201 size_t i;
2202 int r;
2203
2204 debug2_f("checking for %zu deprecated keys", ctx->nold);
2205 for (i = 0; i < options.num_user_hostfiles; i++) {
2206 debug3_f("searching %s for %s / %s",
2207 options.user_hostfiles[i], ctx->host_str,
2208 ctx->ip_str ? ctx->ip_str : "(none)");
2209 if ((r = hostkeys_foreach(options.user_hostfiles[i],
2210 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str,
2211 HKF_WANT_PARSE_KEY, 0)) != 0) {
2212 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
2213 debug_f("hostkeys file %s does not exist",
2214 options.user_hostfiles[i]);
2215 continue;
2216 }
2217 error_fr(r, "hostkeys_foreach failed for %s",
2218 options.user_hostfiles[i]);
2219 return -1;
2220 }
2221 }
2222 return 0;
2223 }
2224
2225 static void
hostkey_change_preamble(LogLevel loglevel)2226 hostkey_change_preamble(LogLevel loglevel)
2227 {
2228 do_log2(loglevel, "The server has updated its host keys.");
2229 do_log2(loglevel, "These changes were verified by the server's "
2230 "existing trusted key.");
2231 }
2232
2233 static void
update_known_hosts(struct hostkeys_update_ctx * ctx)2234 update_known_hosts(struct hostkeys_update_ctx *ctx)
2235 {
2236 int r, was_raw = 0, first = 1;
2237 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK;
2238 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
2239 char *fp, *response;
2240 size_t i;
2241 struct stat sb;
2242
2243 for (i = 0; i < ctx->nkeys; i++) {
2244 if (!ctx->keys_verified[i])
2245 continue;
2246 if ((fp = sshkey_fingerprint(ctx->keys[i],
2247 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2248 fatal_f("sshkey_fingerprint failed");
2249 if (first && asking)
2250 hostkey_change_preamble(loglevel);
2251 do_log2(loglevel, "Learned new hostkey: %s %s",
2252 sshkey_type(ctx->keys[i]), fp);
2253 first = 0;
2254 free(fp);
2255 }
2256 for (i = 0; i < ctx->nold; i++) {
2257 if ((fp = sshkey_fingerprint(ctx->old_keys[i],
2258 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2259 fatal_f("sshkey_fingerprint failed");
2260 if (first && asking)
2261 hostkey_change_preamble(loglevel);
2262 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
2263 sshkey_type(ctx->old_keys[i]), fp);
2264 first = 0;
2265 free(fp);
2266 }
2267 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
2268 if (get_saved_tio() != NULL) {
2269 leave_raw_mode(1);
2270 was_raw = 1;
2271 }
2272 response = NULL;
2273 for (i = 0; !quit_pending && i < 3; i++) {
2274 free(response);
2275 response = read_passphrase("Accept updated hostkeys? "
2276 "(yes/no): ", RP_ECHO);
2277 if (response != NULL && strcasecmp(response, "yes") == 0)
2278 break;
2279 else if (quit_pending || response == NULL ||
2280 strcasecmp(response, "no") == 0) {
2281 options.update_hostkeys = 0;
2282 break;
2283 } else {
2284 do_log2(loglevel, "Please enter "
2285 "\"yes\" or \"no\"");
2286 }
2287 }
2288 if (quit_pending || i >= 3 || response == NULL)
2289 options.update_hostkeys = 0;
2290 free(response);
2291 if (was_raw)
2292 enter_raw_mode(1);
2293 }
2294 if (options.update_hostkeys == 0)
2295 return;
2296 /*
2297 * Now that all the keys are verified, we can go ahead and replace
2298 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
2299 * cancel the operation).
2300 */
2301 for (i = 0; i < options.num_user_hostfiles; i++) {
2302 /*
2303 * NB. keys are only added to hostfiles[0], for the rest we
2304 * just delete the hostname entries.
2305 */
2306 if (stat(options.user_hostfiles[i], &sb) != 0) {
2307 if (errno == ENOENT) {
2308 debug_f("known hosts file %s does not "
2309 "exist", options.user_hostfiles[i]);
2310 } else {
2311 error_f("known hosts file %s "
2312 "inaccessible: %s",
2313 options.user_hostfiles[i], strerror(errno));
2314 }
2315 continue;
2316 }
2317 if ((r = hostfile_replace_entries(options.user_hostfiles[i],
2318 ctx->host_str, ctx->ip_str,
2319 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0,
2320 options.hash_known_hosts, 0,
2321 options.fingerprint_hash)) != 0) {
2322 error_fr(r, "hostfile_replace_entries failed for %s",
2323 options.user_hostfiles[i]);
2324 }
2325 }
2326 }
2327
2328 static void
client_global_hostkeys_prove_confirm(struct ssh * ssh,int type,u_int32_t seq,void * _ctx)2329 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type,
2330 u_int32_t seq, void *_ctx)
2331 {
2332 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2333 size_t i, ndone;
2334 struct sshbuf *signdata;
2335 int r, plaintype;
2336 const u_char *sig;
2337 const char *rsa_kexalg = NULL;
2338 char *alg = NULL;
2339 size_t siglen;
2340
2341 if (ctx->nnew == 0)
2342 fatal_f("ctx->nnew == 0"); /* sanity */
2343 if (type != SSH2_MSG_REQUEST_SUCCESS) {
2344 error("Server failed to confirm ownership of "
2345 "private host keys");
2346 hostkeys_update_ctx_free(ctx);
2347 return;
2348 }
2349 if (sshkey_type_plain(sshkey_type_from_name(
2350 ssh->kex->hostkey_alg)) == KEY_RSA)
2351 rsa_kexalg = ssh->kex->hostkey_alg;
2352 if ((signdata = sshbuf_new()) == NULL)
2353 fatal_f("sshbuf_new failed");
2354 /*
2355 * Expect a signature for each of the ctx->nnew private keys we
2356 * haven't seen before. They will be in the same order as the
2357 * ctx->keys where the corresponding ctx->keys_match[i] == 0.
2358 */
2359 for (ndone = i = 0; i < ctx->nkeys; i++) {
2360 if (ctx->keys_match[i])
2361 continue;
2362 plaintype = sshkey_type_plain(ctx->keys[i]->type);
2363 /* Prepare data to be signed: session ID, unique string, key */
2364 sshbuf_reset(signdata);
2365 if ( (r = sshbuf_put_cstring(signdata,
2366 "hostkeys-prove-00@openssh.com")) != 0 ||
2367 (r = sshbuf_put_stringb(signdata,
2368 ssh->kex->session_id)) != 0 ||
2369 (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
2370 fatal_fr(r, "compose signdata");
2371 /* Extract and verify signature */
2372 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
2373 error_fr(r, "parse sig");
2374 goto out;
2375 }
2376 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) {
2377 error_fr(r, "server gave unintelligible signature "
2378 "for %s key %zu", sshkey_type(ctx->keys[i]), i);
2379 goto out;
2380 }
2381 /*
2382 * Special case for RSA keys: if a RSA hostkey was negotiated,
2383 * then use its signature type for verification of RSA hostkey
2384 * proofs. Otherwise, accept only RSA-SHA256/512 signatures.
2385 */
2386 if (plaintype == KEY_RSA && rsa_kexalg == NULL &&
2387 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) {
2388 debug_f("server used untrusted RSA signature algorithm "
2389 "%s for key %zu, disregarding", alg, i);
2390 free(alg);
2391 /* zap the key from the list */
2392 sshkey_free(ctx->keys[i]);
2393 ctx->keys[i] = NULL;
2394 ndone++;
2395 continue;
2396 }
2397 debug3_f("verify %s key %zu using sigalg %s",
2398 sshkey_type(ctx->keys[i]), i, alg);
2399 free(alg);
2400 if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
2401 sshbuf_ptr(signdata), sshbuf_len(signdata),
2402 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) {
2403 error_fr(r, "server gave bad signature for %s key %zu",
2404 sshkey_type(ctx->keys[i]), i);
2405 goto out;
2406 }
2407 /* Key is good. Mark it as 'seen' */
2408 ctx->keys_verified[i] = 1;
2409 ndone++;
2410 }
2411 /* Shouldn't happen */
2412 if (ndone != ctx->nnew)
2413 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew);
2414 if ((r = sshpkt_get_end(ssh)) != 0) {
2415 error_f("protocol error");
2416 goto out;
2417 }
2418
2419 /* Make the edits to known_hosts */
2420 update_known_hosts(ctx);
2421 out:
2422 hostkeys_update_ctx_free(ctx);
2423 hostkeys_update_complete = 1;
2424 client_repledge();
2425 }
2426
2427 /*
2428 * Handle hostkeys-00@openssh.com global request to inform the client of all
2429 * the server's hostkeys. The keys are checked against the user's
2430 * HostkeyAlgorithms preference before they are accepted.
2431 */
2432 static int
client_input_hostkeys(struct ssh * ssh)2433 client_input_hostkeys(struct ssh *ssh)
2434 {
2435 const u_char *blob = NULL;
2436 size_t i, len = 0;
2437 struct sshbuf *buf = NULL;
2438 struct sshkey *key = NULL, **tmp;
2439 int r, prove_sent = 0;
2440 char *fp;
2441 static int hostkeys_seen = 0; /* XXX use struct ssh */
2442 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
2443 struct hostkeys_update_ctx *ctx = NULL;
2444 u_int want;
2445
2446 if (hostkeys_seen)
2447 fatal_f("server already sent hostkeys");
2448 if (!can_update_hostkeys())
2449 return 1;
2450 hostkeys_seen = 1;
2451
2452 ctx = xcalloc(1, sizeof(*ctx));
2453 while (ssh_packet_remaining(ssh) > 0) {
2454 sshkey_free(key);
2455 key = NULL;
2456 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
2457 error_fr(r, "parse key");
2458 goto out;
2459 }
2460 if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
2461 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ?
2462 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR,
2463 "convert key");
2464 continue;
2465 }
2466 fp = sshkey_fingerprint(key, options.fingerprint_hash,
2467 SSH_FP_DEFAULT);
2468 debug3_f("received %s key %s", sshkey_type(key), fp);
2469 free(fp);
2470
2471 if (!hostkey_accepted_by_hostkeyalgs(key)) {
2472 debug3_f("%s key not permitted by "
2473 "HostkeyAlgorithms", sshkey_ssh_name(key));
2474 continue;
2475 }
2476 /* Skip certs */
2477 if (sshkey_is_cert(key)) {
2478 debug3_f("%s key is a certificate; skipping",
2479 sshkey_ssh_name(key));
2480 continue;
2481 }
2482 /* Ensure keys are unique */
2483 for (i = 0; i < ctx->nkeys; i++) {
2484 if (sshkey_equal(key, ctx->keys[i])) {
2485 error_f("received duplicated %s host key",
2486 sshkey_ssh_name(key));
2487 goto out;
2488 }
2489 }
2490 /* Key is good, record it */
2491 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1,
2492 sizeof(*ctx->keys))) == NULL)
2493 fatal_f("recallocarray failed nkeys = %zu",
2494 ctx->nkeys);
2495 ctx->keys = tmp;
2496 ctx->keys[ctx->nkeys++] = key;
2497 key = NULL;
2498 }
2499
2500 if (ctx->nkeys == 0) {
2501 debug_f("server sent no hostkeys");
2502 goto out;
2503 }
2504
2505 if ((ctx->keys_match = calloc(ctx->nkeys,
2506 sizeof(*ctx->keys_match))) == NULL ||
2507 (ctx->keys_verified = calloc(ctx->nkeys,
2508 sizeof(*ctx->keys_verified))) == NULL)
2509 fatal_f("calloc failed");
2510
2511 get_hostfile_hostname_ipaddr(host,
2512 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
2513 options.port, &ctx->host_str,
2514 options.check_host_ip ? &ctx->ip_str : NULL);
2515
2516 /* Find which keys we already know about. */
2517 for (i = 0; i < options.num_user_hostfiles; i++) {
2518 debug_f("searching %s for %s / %s",
2519 options.user_hostfiles[i], ctx->host_str,
2520 ctx->ip_str ? ctx->ip_str : "(none)");
2521 if ((r = hostkeys_foreach(options.user_hostfiles[i],
2522 hostkeys_find, ctx, ctx->host_str, ctx->ip_str,
2523 HKF_WANT_PARSE_KEY, 0)) != 0) {
2524 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
2525 debug_f("hostkeys file %s does not exist",
2526 options.user_hostfiles[i]);
2527 continue;
2528 }
2529 error_fr(r, "hostkeys_foreach failed for %s",
2530 options.user_hostfiles[i]);
2531 goto out;
2532 }
2533 }
2534
2535 /* Figure out if we have any new keys to add */
2536 ctx->nnew = ctx->nincomplete = 0;
2537 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0);
2538 for (i = 0; i < ctx->nkeys; i++) {
2539 if (ctx->keys_match[i] == 0)
2540 ctx->nnew++;
2541 if ((ctx->keys_match[i] & want) != want)
2542 ctx->nincomplete++;
2543 }
2544
2545 debug3_f("%zu server keys: %zu new, %zu retained, "
2546 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew,
2547 ctx->nkeys - ctx->nnew - ctx->nincomplete,
2548 ctx->nincomplete, ctx->nold);
2549
2550 if (ctx->nnew == 0 && ctx->nold == 0) {
2551 debug_f("no new or deprecated keys from server");
2552 goto out;
2553 }
2554
2555 /* Various reasons why we cannot proceed with the update */
2556 if (ctx->complex_hostspec) {
2557 debug_f("CA/revocation marker, manual host list or wildcard "
2558 "host pattern found, skipping UserKnownHostsFile update");
2559 goto out;
2560 }
2561 if (ctx->other_name_seen) {
2562 debug_f("host key found matching a different name/address, "
2563 "skipping UserKnownHostsFile update");
2564 goto out;
2565 }
2566 /*
2567 * If removing keys, check whether they appear under different
2568 * names/addresses and refuse to proceed if they do. This avoids
2569 * cases such as hosts with multiple names becoming inconsistent
2570 * with regards to CheckHostIP entries.
2571 * XXX UpdateHostkeys=force to override this (and other) checks?
2572 */
2573 if (ctx->nold != 0) {
2574 if (check_old_keys_othernames(ctx) != 0)
2575 goto out; /* error already logged */
2576 if (ctx->old_key_seen) {
2577 debug_f("key(s) for %s%s%s exist under other names; "
2578 "skipping UserKnownHostsFile update",
2579 ctx->host_str, ctx->ip_str == NULL ? "" : ",",
2580 ctx->ip_str == NULL ? "" : ctx->ip_str);
2581 goto out;
2582 }
2583 }
2584
2585 if (ctx->nnew == 0) {
2586 /*
2587 * We have some keys to remove or fix matching for.
2588 * We can proceed to do this without requiring a fresh proof
2589 * from the server.
2590 */
2591 update_known_hosts(ctx);
2592 goto out;
2593 }
2594 /*
2595 * We have received previously-unseen keys from the server.
2596 * Ask the server to confirm ownership of the private halves.
2597 */
2598 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew);
2599 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2600 (r = sshpkt_put_cstring(ssh,
2601 "hostkeys-prove-00@openssh.com")) != 0 ||
2602 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
2603 fatal_fr(r, "prepare hostkeys-prove");
2604 if ((buf = sshbuf_new()) == NULL)
2605 fatal_f("sshbuf_new");
2606 for (i = 0; i < ctx->nkeys; i++) {
2607 if (ctx->keys_match[i])
2608 continue;
2609 sshbuf_reset(buf);
2610 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 ||
2611 (r = sshpkt_put_stringb(ssh, buf)) != 0)
2612 fatal_fr(r, "assemble hostkeys-prove");
2613 }
2614 if ((r = sshpkt_send(ssh)) != 0)
2615 fatal_fr(r, "send hostkeys-prove");
2616 client_register_global_confirm(
2617 client_global_hostkeys_prove_confirm, ctx);
2618 ctx = NULL; /* will be freed in callback */
2619 prove_sent = 1;
2620
2621 /* Success */
2622 out:
2623 hostkeys_update_ctx_free(ctx);
2624 sshkey_free(key);
2625 sshbuf_free(buf);
2626 if (!prove_sent) {
2627 /* UpdateHostkeys handling completed */
2628 hostkeys_update_complete = 1;
2629 client_repledge();
2630 }
2631 /*
2632 * NB. Return success for all cases. The server doesn't need to know
2633 * what the client does with its hosts file.
2634 */
2635 return 1;
2636 }
2637
2638 static int
client_input_global_request(int type,u_int32_t seq,struct ssh * ssh)2639 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
2640 {
2641 char *rtype;
2642 u_char want_reply;
2643 int r, success = 0;
2644
2645 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
2646 (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
2647 goto out;
2648 debug("client_input_global_request: rtype %s want_reply %d",
2649 rtype, want_reply);
2650 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
2651 success = client_input_hostkeys(ssh);
2652 if (want_reply) {
2653 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS :
2654 SSH2_MSG_REQUEST_FAILURE)) != 0 ||
2655 (r = sshpkt_send(ssh)) != 0 ||
2656 (r = ssh_packet_write_wait(ssh)) != 0)
2657 goto out;
2658 }
2659 r = 0;
2660 out:
2661 free(rtype);
2662 return r;
2663 }
2664
2665 static void
client_send_env(struct ssh * ssh,int id,const char * name,const char * val)2666 client_send_env(struct ssh *ssh, int id, const char *name, const char *val)
2667 {
2668 int r;
2669
2670 debug("channel %d: setting env %s = \"%s\"", id, name, val);
2671 channel_request_start(ssh, id, "env", 0);
2672 if ((r = sshpkt_put_cstring(ssh, name)) != 0 ||
2673 (r = sshpkt_put_cstring(ssh, val)) != 0 ||
2674 (r = sshpkt_send(ssh)) != 0)
2675 fatal_fr(r, "send setenv");
2676 }
2677
2678 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)2679 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
2680 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd,
2681 char **env)
2682 {
2683 size_t i, j, len;
2684 int matched, r;
2685 char *name, *val;
2686 Channel *c = NULL;
2687
2688 debug2_f("id %d", id);
2689
2690 if ((c = channel_lookup(ssh, id)) == NULL)
2691 fatal_f("channel %d: unknown channel", id);
2692
2693 ssh_packet_set_interactive(ssh, want_tty,
2694 options.ip_qos_interactive, options.ip_qos_bulk);
2695
2696 if (want_tty) {
2697 struct winsize ws;
2698
2699 /* Store window size in the packet. */
2700 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1)
2701 memset(&ws, 0, sizeof(ws));
2702
2703 channel_request_start(ssh, id, "pty-req", 1);
2704 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
2705 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : ""))
2706 != 0 ||
2707 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
2708 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
2709 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
2710 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0)
2711 fatal_fr(r, "build pty-req");
2712 if (tiop == NULL)
2713 tiop = get_saved_tio();
2714 ssh_tty_make_modes(ssh, -1, tiop);
2715 if ((r = sshpkt_send(ssh)) != 0)
2716 fatal_fr(r, "send pty-req");
2717 /* XXX wait for reply */
2718 c->client_tty = 1;
2719 }
2720
2721 /* Transfer any environment variables from client to server */
2722 if (options.num_send_env != 0 && env != NULL) {
2723 debug("Sending environment.");
2724 for (i = 0; env[i] != NULL; i++) {
2725 /* Split */
2726 name = xstrdup(env[i]);
2727 if ((val = strchr(name, '=')) == NULL) {
2728 free(name);
2729 continue;
2730 }
2731 *val++ = '\0';
2732
2733 matched = 0;
2734 for (j = 0; j < options.num_send_env; j++) {
2735 if (match_pattern(name, options.send_env[j])) {
2736 matched = 1;
2737 break;
2738 }
2739 }
2740 if (!matched) {
2741 debug3("Ignored env %s", name);
2742 free(name);
2743 continue;
2744 }
2745 client_send_env(ssh, id, name, val);
2746 free(name);
2747 }
2748 }
2749 for (i = 0; i < options.num_setenv; i++) {
2750 /* Split */
2751 name = xstrdup(options.setenv[i]);
2752 if ((val = strchr(name, '=')) == NULL) {
2753 free(name);
2754 continue;
2755 }
2756 *val++ = '\0';
2757 client_send_env(ssh, id, name, val);
2758 free(name);
2759 }
2760
2761 len = sshbuf_len(cmd);
2762 if (len > 0) {
2763 if (len > 900)
2764 len = 900;
2765 if (want_subsystem) {
2766 debug("Sending subsystem: %.*s",
2767 (int)len, (const u_char*)sshbuf_ptr(cmd));
2768 channel_request_start(ssh, id, "subsystem", 1);
2769 client_expect_confirm(ssh, id, "subsystem",
2770 CONFIRM_CLOSE);
2771 } else {
2772 debug("Sending command: %.*s",
2773 (int)len, (const u_char*)sshbuf_ptr(cmd));
2774 channel_request_start(ssh, id, "exec", 1);
2775 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
2776 }
2777 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 ||
2778 (r = sshpkt_send(ssh)) != 0)
2779 fatal_fr(r, "send command");
2780 } else {
2781 channel_request_start(ssh, id, "shell", 1);
2782 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
2783 if ((r = sshpkt_send(ssh)) != 0)
2784 fatal_fr(r, "send shell");
2785 }
2786
2787 session_setup_complete = 1;
2788 client_repledge();
2789 }
2790
2791 static void
client_init_dispatch(struct ssh * ssh)2792 client_init_dispatch(struct ssh *ssh)
2793 {
2794 ssh_dispatch_init(ssh, &dispatch_protocol_error);
2795
2796 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
2797 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
2798 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
2799 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
2800 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
2801 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
2802 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
2803 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
2804 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
2805 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
2806 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
2807 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
2808
2809 /* rekeying */
2810 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
2811
2812 /* global request reply messages */
2813 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
2814 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
2815 }
2816
2817 void
client_stop_mux(void)2818 client_stop_mux(void)
2819 {
2820 if (options.control_path != NULL && muxserver_sock != -1)
2821 unlink(options.control_path);
2822 /*
2823 * If we are in persist mode, or don't have a shell, signal that we
2824 * should close when all active channels are closed.
2825 */
2826 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) {
2827 session_closed = 1;
2828 setproctitle("[stopped mux]");
2829 }
2830 }
2831
2832 /* client specific fatal cleanup */
2833 void
cleanup_exit(int i)2834 cleanup_exit(int i)
2835 {
2836 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2837 if (options.control_path != NULL && muxserver_sock != -1)
2838 unlink(options.control_path);
2839 ssh_kill_proxy_command();
2840 _exit(i);
2841 }
2842