1 /* $NetBSD: clientloop.c,v 1.37 2023/07/26 17:58:15 christos Exp $ */
2 /* $OpenBSD: clientloop.c,v 1.390 2023/03/08 04:43:12 guenther Exp $ */
3 /*
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * All rights reserved
7 * The main loop for the interactive session (client side).
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 *
16 * Copyright (c) 1999 Theo de Raadt. All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 *
39 * SSH2 support added by Markus Friedl.
40 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved.
41 *
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions
44 * are met:
45 * 1. Redistributions of source code must retain the above copyright
46 * notice, this list of conditions and the following disclaimer.
47 * 2. Redistributions in binary form must reproduce the above copyright
48 * notice, this list of conditions and the following disclaimer in the
49 * documentation and/or other materials provided with the distribution.
50 *
51 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
52 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
53 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
54 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
55 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
56 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
57 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
58 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
59 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
60 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
61 */
62
63 #include "includes.h"
64 __RCSID("$NetBSD: clientloop.c,v 1.37 2023/07/26 17:58:15 christos Exp $");
65
66 #include <sys/types.h>
67 #include <sys/ioctl.h>
68 #include <sys/stat.h>
69 #include <sys/socket.h>
70 #include <sys/time.h>
71 #include <sys/queue.h>
72
73 #include <ctype.h>
74 #include <errno.h>
75 #include <paths.h>
76 #include <poll.h>
77 #include <signal.h>
78 #include <stdio.h>
79 #include <stdlib.h>
80 #include <string.h>
81 #include <stdarg.h>
82 #include <termios.h>
83 #include <pwd.h>
84 #include <unistd.h>
85 #include <limits.h>
86
87 #include "xmalloc.h"
88 #include "ssh.h"
89 #include "ssh2.h"
90 #include "packet.h"
91 #include "sshbuf.h"
92 #include "compat.h"
93 #include "channels.h"
94 #include "dispatch.h"
95 #include "sshkey.h"
96 #include "cipher.h"
97 #include "kex.h"
98 #include "myproposal.h"
99 #include "log.h"
100 #include "misc.h"
101 #include "readconf.h"
102 #include "clientloop.h"
103 #include "sshconnect.h"
104 #include "authfd.h"
105 #include "atomicio.h"
106 #include "sshpty.h"
107 #include "match.h"
108 #include "msg.h"
109 #include "getpeereid.h"
110 #include "ssherr.h"
111 #include "hostfile.h"
112
113 /* Permitted RSA signature algorithms for UpdateHostkeys proofs */
114 #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256"
115
116 /* import options */
117 extern Options options;
118
119 /* Control socket */
120 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */
121
122 /*
123 * Name of the host we are connecting to. This is the name given on the
124 * command line, or the Hostname specified for the user-supplied name in a
125 * configuration file.
126 */
127 extern char *host;
128
129 /*
130 * If this field is not NULL, the ForwardAgent socket is this path and different
131 * instead of SSH_AUTH_SOCK.
132 */
133 extern char *forward_agent_sock_path;
134
135 /*
136 * Flag to indicate that we have received a window change signal which has
137 * not yet been processed. This will cause a message indicating the new
138 * window size to be sent to the server a little later. This is volatile
139 * because this is updated in a signal handler.
140 */
141 static volatile sig_atomic_t received_window_change_signal = 0;
142 static volatile sig_atomic_t received_signal = 0;
143
144 /* Time when backgrounded control master using ControlPersist should exit */
145 static time_t control_persist_exit_time = 0;
146
147 /* Common data for the client loop code. */
148 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
149 static int last_was_cr; /* Last character was a newline. */
150 static int exit_status; /* Used to store the command exit status. */
151 static struct sshbuf *stderr_buffer; /* Used for final exit message. */
152 static int connection_in; /* Connection to server (input). */
153 static int connection_out; /* Connection to server (output). */
154 static int need_rekeying; /* Set to non-zero if rekeying is requested. */
155 static int session_closed; /* In SSH2: login session closed. */
156 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */
157 static time_t server_alive_time; /* Time to do server_alive_check */
158 static int hostkeys_update_complete;
159 static int session_setup_complete;
160
161 static void client_init_dispatch(struct ssh *ssh);
162 int session_ident = -1;
163
164 /* Track escape per proto2 channel */
165 struct escape_filter_ctx {
166 int escape_pending;
167 int escape_char;
168 };
169
170 /* Context for channel confirmation replies */
171 struct channel_reply_ctx {
172 const char *request_type;
173 int id;
174 enum confirm_action action;
175 };
176
177 /* Global request success/failure callbacks */
178 /* XXX move to struct ssh? */
179 struct global_confirm {
180 TAILQ_ENTRY(global_confirm) entry;
181 global_confirm_cb *cb;
182 void *ctx;
183 int ref_count;
184 };
185 TAILQ_HEAD(global_confirms, global_confirm);
186 static struct global_confirms global_confirms =
187 TAILQ_HEAD_INITIALIZER(global_confirms);
188
189 void ssh_process_session2_setup(int, int, int, struct sshbuf *);
190 static void quit_message(const char *fmt, ...)
191 __attribute__((__format__ (printf, 1, 2)));
192
193 static void
quit_message(const char * fmt,...)194 quit_message(const char *fmt, ...)
195 {
196 char *msg;
197 va_list args;
198 int r;
199
200 va_start(args, fmt);
201 xvasprintf(&msg, fmt, args);
202 va_end(args);
203
204 if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0)
205 fatal_fr(r, "sshbuf_putf");
206 quit_pending = 1;
207 }
208
209 /*
210 * Signal handler for the window change signal (SIGWINCH). This just sets a
211 * flag indicating that the window has changed.
212 */
213 static void
window_change_handler(int sig)214 window_change_handler(int sig)
215 {
216 received_window_change_signal = 1;
217 }
218
219 /*
220 * Signal handler for signals that cause the program to terminate. These
221 * signals must be trapped to restore terminal modes.
222 */
223 static void
signal_handler(int sig)224 signal_handler(int sig)
225 {
226 received_signal = sig;
227 quit_pending = 1;
228 }
229
230 /*
231 * Sets control_persist_exit_time to the absolute time when the
232 * backgrounded control master should exit due to expiry of the
233 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded
234 * control master process, or if there is no ControlPersist timeout.
235 */
236 static void
set_control_persist_exit_time(struct ssh * ssh)237 set_control_persist_exit_time(struct ssh *ssh)
238 {
239 if (muxserver_sock == -1 || !options.control_persist
240 || options.control_persist_timeout == 0) {
241 /* not using a ControlPersist timeout */
242 control_persist_exit_time = 0;
243 } else if (channel_still_open(ssh)) {
244 /* some client connections are still open */
245 if (control_persist_exit_time > 0)
246 debug2_f("cancel scheduled exit");
247 control_persist_exit_time = 0;
248 } else if (control_persist_exit_time <= 0) {
249 /* a client connection has recently closed */
250 control_persist_exit_time = monotime() +
251 (time_t)options.control_persist_timeout;
252 debug2_f("schedule exit in %d seconds",
253 options.control_persist_timeout);
254 }
255 /* else we are already counting down to the timeout */
256 }
257
258 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
259 static int
client_x11_display_valid(const char * display)260 client_x11_display_valid(const char *display)
261 {
262 size_t i, dlen;
263
264 if (display == NULL)
265 return 0;
266
267 dlen = strlen(display);
268 for (i = 0; i < dlen; i++) {
269 if (!isalnum((u_char)display[i]) &&
270 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
271 debug("Invalid character '%c' in DISPLAY", display[i]);
272 return 0;
273 }
274 }
275 return 1;
276 }
277
278 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
279 #define X11_TIMEOUT_SLACK 60
280 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)281 client_x11_get_proto(struct ssh *ssh, const char *display,
282 const char *xauth_path, u_int trusted, u_int timeout,
283 char **_proto, char **_data)
284 {
285 char *cmd, line[512], xdisplay[512];
286 char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
287 static char proto[512], data[512];
288 FILE *f;
289 int got_data = 0, generated = 0, do_unlink = 0, r;
290 struct stat st;
291 u_int now, x11_timeout_real;
292
293 *_proto = proto;
294 *_data = data;
295 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';
296
297 if (!client_x11_display_valid(display)) {
298 if (display != NULL)
299 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
300 display);
301 return -1;
302 }
303 if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
304 debug("No xauth program.");
305 xauth_path = NULL;
306 }
307
308 if (xauth_path != NULL) {
309 /*
310 * Handle FamilyLocal case where $DISPLAY does
311 * not match an authorization entry. For this we
312 * just try "xauth list unix:displaynum.screennum".
313 * XXX: "localhost" match to determine FamilyLocal
314 * is not perfect.
315 */
316 if (strncmp(display, "localhost:", 10) == 0) {
317 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
318 display + 10)) < 0 ||
319 (size_t)r >= sizeof(xdisplay)) {
320 error_f("display name too long");
321 return -1;
322 }
323 display = xdisplay;
324 }
325 if (trusted == 0) {
326 /*
327 * Generate an untrusted X11 auth cookie.
328 *
329 * The authentication cookie should briefly outlive
330 * ssh's willingness to forward X11 connections to
331 * avoid nasty fail-open behaviour in the X server.
332 */
333 mktemp_proto(xauthdir, sizeof(xauthdir));
334 if (mkdtemp(xauthdir) == NULL) {
335 error_f("mkdtemp: %s", strerror(errno));
336 return -1;
337 }
338 do_unlink = 1;
339 if ((r = snprintf(xauthfile, sizeof(xauthfile),
340 "%s/xauthfile", xauthdir)) < 0 ||
341 (size_t)r >= sizeof(xauthfile)) {
342 error_f("xauthfile path too long");
343 rmdir(xauthdir);
344 return -1;
345 }
346
347 if (timeout == 0) {
348 /* auth doesn't time out */
349 xasprintf(&cmd, "%s -f %s generate %s %s "
350 "untrusted 2>%s",
351 xauth_path, xauthfile, display,
352 SSH_X11_PROTO, _PATH_DEVNULL);
353 } else {
354 /* Add some slack to requested expiry */
355 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK)
356 x11_timeout_real = timeout +
357 X11_TIMEOUT_SLACK;
358 else {
359 /* Don't overflow on long timeouts */
360 x11_timeout_real = UINT_MAX;
361 }
362 xasprintf(&cmd, "%s -f %s generate %s %s "
363 "untrusted timeout %u 2>%s",
364 xauth_path, xauthfile, display,
365 SSH_X11_PROTO, x11_timeout_real,
366 _PATH_DEVNULL);
367 }
368 debug2_f("xauth command: %s", cmd);
369
370 if (timeout != 0 && x11_refuse_time == 0) {
371 now = monotime() + 1;
372 if (SSH_TIME_T_MAX - timeout < now)
373 x11_refuse_time = SSH_TIME_T_MAX;
374 else
375 x11_refuse_time = now + timeout;
376 channel_set_x11_refuse_time(ssh,
377 x11_refuse_time);
378 }
379 if (system(cmd) == 0)
380 generated = 1;
381 free(cmd);
382 }
383
384 /*
385 * When in untrusted mode, we read the cookie only if it was
386 * successfully generated as an untrusted one in the step
387 * above.
388 */
389 if (trusted || generated) {
390 xasprintf(&cmd,
391 "%s %s%s list %s 2>" _PATH_DEVNULL,
392 xauth_path,
393 generated ? "-f " : "" ,
394 generated ? xauthfile : "",
395 display);
396 debug2("x11_get_proto: %s", cmd);
397 f = popen(cmd, "r");
398 if (f && fgets(line, sizeof(line), f) &&
399 sscanf(line, "%*s %511s %511s", proto, data) == 2)
400 got_data = 1;
401 if (f)
402 pclose(f);
403 free(cmd);
404 }
405 }
406
407 if (do_unlink) {
408 unlink(xauthfile);
409 rmdir(xauthdir);
410 }
411
412 /* Don't fall back to fake X11 data for untrusted forwarding */
413 if (!trusted && !got_data) {
414 error("Warning: untrusted X11 forwarding setup failed: "
415 "xauth key data not generated");
416 return -1;
417 }
418
419 /*
420 * If we didn't get authentication data, just make up some
421 * data. The forwarding code will check the validity of the
422 * response anyway, and substitute this data. The X11
423 * server, however, will ignore this fake data and use
424 * whatever authentication mechanisms it was using otherwise
425 * for the local connection.
426 */
427 if (!got_data) {
428 u_int8_t rnd[16];
429 u_int i;
430
431 logit("Warning: No xauth data; "
432 "using fake authentication data for X11 forwarding.");
433 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
434 arc4random_buf(rnd, sizeof(rnd));
435 for (i = 0; i < sizeof(rnd); i++) {
436 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
437 rnd[i]);
438 }
439 }
440
441 return 0;
442 }
443
444 /*
445 * Checks if the client window has changed, and sends a packet about it to
446 * the server if so. The actual change is detected elsewhere (by a software
447 * interrupt on Unix); this just checks the flag and sends a message if
448 * appropriate.
449 */
450
451 static void
client_check_window_change(struct ssh * ssh)452 client_check_window_change(struct ssh *ssh)
453 {
454 if (!received_window_change_signal)
455 return;
456 received_window_change_signal = 0;
457 debug2_f("changed");
458 channel_send_window_changes(ssh);
459 }
460
461 static int
client_global_request_reply(int type,u_int32_t seq,struct ssh * ssh)462 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
463 {
464 struct global_confirm *gc;
465
466 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
467 return 0;
468 if (gc->cb != NULL)
469 gc->cb(ssh, type, seq, gc->ctx);
470 if (--gc->ref_count <= 0) {
471 TAILQ_REMOVE(&global_confirms, gc, entry);
472 freezero(gc, sizeof(*gc));
473 }
474
475 ssh_packet_set_alive_timeouts(ssh, 0);
476 return 0;
477 }
478
479 static void
schedule_server_alive_check(void)480 schedule_server_alive_check(void)
481 {
482 if (options.server_alive_interval > 0)
483 server_alive_time = monotime() + options.server_alive_interval;
484 }
485
486 static void
server_alive_check(struct ssh * ssh)487 server_alive_check(struct ssh *ssh)
488 {
489 int r;
490
491 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) {
492 logit("Timeout, server %s not responding.", host);
493 cleanup_exit(255);
494 }
495 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
496 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 ||
497 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */
498 (r = sshpkt_send(ssh)) != 0)
499 fatal_fr(r, "send packet");
500 /* Insert an empty placeholder to maintain ordering */
501 client_register_global_confirm(NULL, NULL);
502 schedule_server_alive_check();
503 }
504
505 /*
506 * Waits until the client can do something (some data becomes available on
507 * one of the file descriptors).
508 */
509 static void
client_wait_until_can_do_something(struct ssh * ssh,struct pollfd ** pfdp,u_int * npfd_allocp,u_int * npfd_activep,int rekeying,int * conn_in_readyp,int * conn_out_readyp)510 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp,
511 u_int *npfd_allocp, u_int *npfd_activep, int rekeying,
512 int *conn_in_readyp, int *conn_out_readyp)
513 {
514 struct timespec timeout;
515 int ret;
516 u_int p;
517
518 *conn_in_readyp = *conn_out_readyp = 0;
519
520 /* Prepare channel poll. First two pollfd entries are reserved */
521 ptimeout_init(&timeout);
522 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout);
523 if (*npfd_activep < 2)
524 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
525
526 /* channel_prepare_poll could have closed the last channel */
527 if (session_closed && !channel_still_open(ssh) &&
528 !ssh_packet_have_data_to_write(ssh)) {
529 /* clear events since we did not call poll() */
530 for (p = 0; p < *npfd_activep; p++)
531 (*pfdp)[p].revents = 0;
532 return;
533 }
534
535 /* Monitor server connection on reserved pollfd entries */
536 (*pfdp)[0].fd = connection_in;
537 (*pfdp)[0].events = POLLIN;
538 (*pfdp)[1].fd = connection_out;
539 (*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;
540
541 /*
542 * Wait for something to happen. This will suspend the process until
543 * some polled descriptor can be read, written, or has some other
544 * event pending, or a timeout expires.
545 */
546 set_control_persist_exit_time(ssh);
547 if (control_persist_exit_time > 0)
548 ptimeout_deadline_monotime(&timeout, control_persist_exit_time);
549 if (options.server_alive_interval > 0)
550 ptimeout_deadline_monotime(&timeout, server_alive_time);
551 if (options.rekey_interval > 0 && !rekeying) {
552 ptimeout_deadline_sec(&timeout,
553 ssh_packet_get_rekey_timeout(ssh));
554 }
555
556 ret = poll(*pfdp, *npfd_activep, ptimeout_get_ms(&timeout));
557
558 if (ret == -1) {
559 /*
560 * We have to clear the events because we return.
561 * We have to return, because the mainloop checks for the flags
562 * set by the signal handlers.
563 */
564 for (p = 0; p < *npfd_activep; p++)
565 (*pfdp)[p].revents = 0;
566 if (errno == EINTR)
567 return;
568 /* Note: we might still have data in the buffers. */
569 quit_message("poll: %s", strerror(errno));
570 return;
571 }
572
573 *conn_in_readyp = (*pfdp)[0].revents != 0;
574 *conn_out_readyp = (*pfdp)[1].revents != 0;
575
576 if (options.server_alive_interval > 0 && !*conn_in_readyp &&
577 monotime() >= server_alive_time) {
578 /*
579 * ServerAlive check is needed. We can't rely on the poll
580 * timing out since traffic on the client side such as port
581 * forwards can keep waking it up.
582 */
583 server_alive_check(ssh);
584 }
585 }
586
587 static void
client_suspend_self(struct sshbuf * bin,struct sshbuf * bout,struct sshbuf * berr)588 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr)
589 {
590 /* Flush stdout and stderr buffers. */
591 if (sshbuf_len(bout) > 0)
592 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout),
593 sshbuf_len(bout));
594 if (sshbuf_len(berr) > 0)
595 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr),
596 sshbuf_len(berr));
597
598 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
599
600 sshbuf_reset(bin);
601 sshbuf_reset(bout);
602 sshbuf_reset(berr);
603
604 /* Send the suspend signal to the program itself. */
605 kill(getpid(), SIGTSTP);
606
607 /* Reset window sizes in case they have changed */
608 received_window_change_signal = 1;
609
610 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
611 }
612
613 static void
client_process_net_input(struct ssh * ssh)614 client_process_net_input(struct ssh *ssh)
615 {
616 int r;
617
618 /*
619 * Read input from the server, and add any such data to the buffer of
620 * the packet subsystem.
621 */
622 schedule_server_alive_check();
623 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
624 return; /* success */
625 if (r == SSH_ERR_SYSTEM_ERROR) {
626 if (errno == EAGAIN || errno == EINTR)
627 return;
628 if (errno == EPIPE) {
629 quit_message("Connection to %s closed by remote host.",
630 host);
631 return;
632 }
633 }
634 quit_message("Read from remote host %s: %s", host, ssh_err(r));
635 }
636
637 static void
client_status_confirm(struct ssh * ssh,int type,Channel * c,void * ctx)638 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx)
639 {
640 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
641 char errmsg[256];
642 int r, tochan;
643
644 /*
645 * If a TTY was explicitly requested, then a failure to allocate
646 * one is fatal.
647 */
648 if (cr->action == CONFIRM_TTY &&
649 (options.request_tty == REQUEST_TTY_FORCE ||
650 options.request_tty == REQUEST_TTY_YES))
651 cr->action = CONFIRM_CLOSE;
652
653 /* XXX suppress on mux _client_ quietmode */
654 tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
655 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
656
657 if (type == SSH2_MSG_CHANNEL_SUCCESS) {
658 debug2("%s request accepted on channel %d",
659 cr->request_type, c->self);
660 } else if (type == SSH2_MSG_CHANNEL_FAILURE) {
661 if (tochan) {
662 snprintf(errmsg, sizeof(errmsg),
663 "%s request failed\r\n", cr->request_type);
664 } else {
665 snprintf(errmsg, sizeof(errmsg),
666 "%s request failed on channel %d",
667 cr->request_type, c->self);
668 }
669 /* If error occurred on primary session channel, then exit */
670 if (cr->action == CONFIRM_CLOSE && c->self == session_ident)
671 fatal("%s", errmsg);
672 /*
673 * If error occurred on mux client, append to
674 * their stderr.
675 */
676 if (tochan) {
677 debug3_f("channel %d: mux request: %s", c->self,
678 cr->request_type);
679 if ((r = sshbuf_put(c->extended, errmsg,
680 strlen(errmsg))) != 0)
681 fatal_fr(r, "sshbuf_put");
682 } else
683 error("%s", errmsg);
684 if (cr->action == CONFIRM_TTY) {
685 /*
686 * If a TTY allocation error occurred, then arrange
687 * for the correct TTY to leave raw mode.
688 */
689 if (c->self == session_ident)
690 leave_raw_mode(0);
691 else
692 mux_tty_alloc_failed(ssh, c);
693 } else if (cr->action == CONFIRM_CLOSE) {
694 chan_read_failed(ssh, c);
695 chan_write_failed(ssh, c);
696 }
697 }
698 free(cr);
699 }
700
701 static void
client_abandon_status_confirm(struct ssh * ssh,Channel * c,void * ctx)702 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx)
703 {
704 free(ctx);
705 }
706
707 void
client_expect_confirm(struct ssh * ssh,int id,const char * request,enum confirm_action action)708 client_expect_confirm(struct ssh *ssh, int id, const char *request,
709 enum confirm_action action)
710 {
711 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));
712
713 cr->request_type = request;
714 cr->action = action;
715
716 channel_register_status_confirm(ssh, id, client_status_confirm,
717 client_abandon_status_confirm, cr);
718 }
719
720 void
client_register_global_confirm(global_confirm_cb * cb,void * ctx)721 client_register_global_confirm(global_confirm_cb *cb, void *ctx)
722 {
723 struct global_confirm *gc, *last_gc;
724
725 /* Coalesce identical callbacks */
726 last_gc = TAILQ_LAST(&global_confirms, global_confirms);
727 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) {
728 if (++last_gc->ref_count >= INT_MAX)
729 fatal_f("last_gc->ref_count = %d",
730 last_gc->ref_count);
731 return;
732 }
733
734 gc = xcalloc(1, sizeof(*gc));
735 gc->cb = cb;
736 gc->ctx = ctx;
737 gc->ref_count = 1;
738 TAILQ_INSERT_TAIL(&global_confirms, gc, entry);
739 }
740
741 /*
742 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com
743 * hostkey update request.
744 */
745 static int
can_update_hostkeys(void)746 can_update_hostkeys(void)
747 {
748 if (hostkeys_update_complete)
749 return 0;
750 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
751 options.batch_mode)
752 return 0; /* won't ask in batchmode, so don't even try */
753 if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
754 return 0;
755 return 1;
756 }
757
758 static void
client_repledge(void)759 client_repledge(void)
760 {
761 debug3_f("enter");
762
763 /* Might be able to tighten pledge now that session is established */
764 if (options.control_master || options.control_path != NULL ||
765 options.forward_x11 || options.fork_after_authentication ||
766 can_update_hostkeys() ||
767 (session_ident != -1 && !session_setup_complete)) {
768 /* Can't tighten */
769 return;
770 }
771 #ifdef __OpenBSD__
772 /*
773 * LocalCommand and UpdateHostkeys have finished, so can get rid of
774 * filesystem.
775 *
776 * XXX protocol allows a server can to change hostkeys during the
777 * connection at rekey time that could trigger a hostkeys update
778 * but AFAIK no implementations support this. Could improve by
779 * forcing known_hosts to be read-only or via unveil(2).
780 */
781 if (options.num_local_forwards != 0 ||
782 options.num_remote_forwards != 0 ||
783 options.num_permitted_remote_opens != 0 ||
784 options.enable_escape_commandline != 0) {
785 /* rfwd needs inet */
786 debug("pledge: network");
787 if (pledge("stdio unix inet dns proc tty", NULL) == -1)
788 fatal_f("pledge(): %s", strerror(errno));
789 } else if (options.forward_agent != 0) {
790 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */
791 debug("pledge: agent");
792 if (pledge("stdio unix proc tty", NULL) == -1)
793 fatal_f("pledge(): %s", strerror(errno));
794 } else {
795 debug("pledge: fork");
796 if (pledge("stdio proc tty", NULL) == -1)
797 fatal_f("pledge(): %s", strerror(errno));
798 }
799 #endif
800 /* XXX further things to do:
801 *
802 * - might be able to get rid of proc if we kill ~^Z
803 * - ssh -N (no session)
804 * - stdio forwarding
805 * - sessions without tty
806 */
807 }
808
809 static void
process_cmdline(struct ssh * ssh)810 process_cmdline(struct ssh *ssh)
811 {
812 void (*handler)(int);
813 char *s, *cmd;
814 int ok, delete = 0, local = 0, remote = 0, dynamic = 0;
815 struct Forward fwd;
816
817 memset(&fwd, 0, sizeof(fwd));
818
819 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
820 handler = ssh_signal(SIGINT, SIG_IGN);
821 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
822 if (s == NULL)
823 goto out;
824 while (isspace((u_char)*s))
825 s++;
826 if (*s == '-')
827 s++; /* Skip cmdline '-', if any */
828 if (*s == '\0')
829 goto out;
830
831 if (*s == 'h' || *s == 'H' || *s == '?') {
832 logit("Commands:");
833 logit(" -L[bind_address:]port:host:hostport "
834 "Request local forward");
835 logit(" -R[bind_address:]port:host:hostport "
836 "Request remote forward");
837 logit(" -D[bind_address:]port "
838 "Request dynamic forward");
839 logit(" -KL[bind_address:]port "
840 "Cancel local forward");
841 logit(" -KR[bind_address:]port "
842 "Cancel remote forward");
843 logit(" -KD[bind_address:]port "
844 "Cancel dynamic forward");
845 if (!options.permit_local_command)
846 goto out;
847 logit(" !args "
848 "Execute local command");
849 goto out;
850 }
851
852 if (*s == '!' && options.permit_local_command) {
853 s++;
854 ssh_local_cmd(s);
855 goto out;
856 }
857
858 if (*s == 'K') {
859 delete = 1;
860 s++;
861 }
862 if (*s == 'L')
863 local = 1;
864 else if (*s == 'R')
865 remote = 1;
866 else if (*s == 'D')
867 dynamic = 1;
868 else {
869 logit("Invalid command.");
870 goto out;
871 }
872
873 while (isspace((u_char)*++s))
874 ;
875
876 /* XXX update list of forwards in options */
877 if (delete) {
878 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */
879 if (!parse_forward(&fwd, s, 1, 0)) {
880 logit("Bad forwarding close specification.");
881 goto out;
882 }
883 if (remote)
884 ok = channel_request_rforward_cancel(ssh, &fwd) == 0;
885 else if (dynamic)
886 ok = channel_cancel_lport_listener(ssh, &fwd,
887 0, &options.fwd_opts) > 0;
888 else
889 ok = channel_cancel_lport_listener(ssh, &fwd,
890 CHANNEL_CANCEL_PORT_STATIC,
891 &options.fwd_opts) > 0;
892 if (!ok) {
893 logit("Unknown port forwarding.");
894 goto out;
895 }
896 logit("Canceled forwarding.");
897 } else {
898 /* -R specs can be both dynamic or not, so check both. */
899 if (remote) {
900 if (!parse_forward(&fwd, s, 0, remote) &&
901 !parse_forward(&fwd, s, 1, remote)) {
902 logit("Bad remote forwarding specification.");
903 goto out;
904 }
905 } else if (!parse_forward(&fwd, s, dynamic, remote)) {
906 logit("Bad local forwarding specification.");
907 goto out;
908 }
909 if (local || dynamic) {
910 if (!channel_setup_local_fwd_listener(ssh, &fwd,
911 &options.fwd_opts)) {
912 logit("Port forwarding failed.");
913 goto out;
914 }
915 } else {
916 if (channel_request_remote_forwarding(ssh, &fwd) < 0) {
917 logit("Port forwarding failed.");
918 goto out;
919 }
920 }
921 logit("Forwarding port.");
922 }
923
924 out:
925 ssh_signal(SIGINT, handler);
926 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
927 free(cmd);
928 free(fwd.listen_host);
929 free(fwd.listen_path);
930 free(fwd.connect_host);
931 free(fwd.connect_path);
932 }
933
934 /* reasons to suppress output of an escape command in help output */
935 #define SUPPRESS_NEVER 0 /* never suppress, always show */
936 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */
937 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */
938 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */
939 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/
940 struct escape_help_text {
941 const char *cmd;
942 const char *text;
943 unsigned int flags;
944 };
945 static struct escape_help_text esc_txt[] = {
946 {".", "terminate session", SUPPRESS_MUXMASTER},
947 {".", "terminate connection (and any multiplexed sessions)",
948 SUPPRESS_MUXCLIENT},
949 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER},
950 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE},
951 {"R", "request rekey", SUPPRESS_NEVER},
952 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT},
953 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT},
954 {"#", "list forwarded connections", SUPPRESS_NEVER},
955 {"&", "background ssh (when waiting for connections to terminate)",
956 SUPPRESS_MUXCLIENT},
957 {"?", "this message", SUPPRESS_NEVER},
958 };
959
960 static void
print_escape_help(struct sshbuf * b,int escape_char,int mux_client,int using_stderr)961 print_escape_help(struct sshbuf *b, int escape_char, int mux_client,
962 int using_stderr)
963 {
964 unsigned int i, suppress_flags;
965 int r;
966
967 if ((r = sshbuf_putf(b,
968 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0)
969 fatal_fr(r, "sshbuf_putf");
970
971 suppress_flags =
972 (mux_client ? SUPPRESS_MUXCLIENT : 0) |
973 (mux_client ? 0 : SUPPRESS_MUXMASTER) |
974 (using_stderr ? 0 : SUPPRESS_SYSLOG) |
975 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0);
976
977 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
978 if (esc_txt[i].flags & suppress_flags)
979 continue;
980 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n",
981 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0)
982 fatal_fr(r, "sshbuf_putf");
983 }
984
985 if ((r = sshbuf_putf(b,
986 " %c%c - send the escape character by typing it twice\r\n"
987 "(Note that escapes are only recognized immediately after "
988 "newline.)\r\n", escape_char, escape_char)) != 0)
989 fatal_fr(r, "sshbuf_putf");
990 }
991
992 /*
993 * Process the characters one by one.
994 */
995 static int
process_escapes(struct ssh * ssh,Channel * c,struct sshbuf * bin,struct sshbuf * bout,struct sshbuf * berr,const char * buf,int len)996 process_escapes(struct ssh *ssh, Channel *c,
997 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr,
998 const char *buf, int len)
999 {
1000 pid_t pid;
1001 int r, bytes = 0;
1002 u_int i;
1003 u_char ch;
1004 char *s;
1005 struct escape_filter_ctx *efc = c->filter_ctx == NULL ?
1006 NULL : (struct escape_filter_ctx *)c->filter_ctx;
1007
1008 if (c->filter_ctx == NULL)
1009 return 0;
1010
1011 if (len <= 0)
1012 return (0);
1013
1014 for (i = 0; i < (u_int)len; i++) {
1015 /* Get one character at a time. */
1016 ch = buf[i];
1017
1018 if (efc->escape_pending) {
1019 /* We have previously seen an escape character. */
1020 /* Clear the flag now. */
1021 efc->escape_pending = 0;
1022
1023 /* Process the escaped character. */
1024 switch (ch) {
1025 case '.':
1026 /* Terminate the connection. */
1027 if ((r = sshbuf_putf(berr, "%c.\r\n",
1028 efc->escape_char)) != 0)
1029 fatal_fr(r, "sshbuf_putf");
1030 if (c && c->ctl_chan != -1) {
1031 channel_force_close(ssh, c, 1);
1032 return 0;
1033 } else
1034 quit_pending = 1;
1035 return -1;
1036
1037 case 'Z' - 64:
1038 /* XXX support this for mux clients */
1039 if (c && c->ctl_chan != -1) {
1040 char b[16];
1041 noescape:
1042 if (ch == 'Z' - 64)
1043 snprintf(b, sizeof b, "^Z");
1044 else
1045 snprintf(b, sizeof b, "%c", ch);
1046 if ((r = sshbuf_putf(berr,
1047 "%c%s escape not available to "
1048 "multiplexed sessions\r\n",
1049 efc->escape_char, b)) != 0)
1050 fatal_fr(r, "sshbuf_putf");
1051 continue;
1052 }
1053 /* Suspend the program. Inform the user */
1054 if ((r = sshbuf_putf(berr,
1055 "%c^Z [suspend ssh]\r\n",
1056 efc->escape_char)) != 0)
1057 fatal_fr(r, "sshbuf_putf");
1058
1059 /* Restore terminal modes and suspend. */
1060 client_suspend_self(bin, bout, berr);
1061
1062 /* We have been continued. */
1063 continue;
1064
1065 case 'B':
1066 if ((r = sshbuf_putf(berr,
1067 "%cB\r\n", efc->escape_char)) != 0)
1068 fatal_fr(r, "sshbuf_putf");
1069 channel_request_start(ssh, c->self, "break", 0);
1070 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 ||
1071 (r = sshpkt_send(ssh)) != 0)
1072 fatal_fr(r, "send packet");
1073 continue;
1074
1075 case 'R':
1076 if (ssh->compat & SSH_BUG_NOREKEY)
1077 logit("Server does not "
1078 "support re-keying");
1079 else
1080 need_rekeying = 1;
1081 continue;
1082
1083 case 'V':
1084 /* FALLTHROUGH */
1085 case 'v':
1086 if (c && c->ctl_chan != -1)
1087 goto noescape;
1088 if (!log_is_on_stderr()) {
1089 if ((r = sshbuf_putf(berr,
1090 "%c%c [Logging to syslog]\r\n",
1091 efc->escape_char, ch)) != 0)
1092 fatal_fr(r, "sshbuf_putf");
1093 continue;
1094 }
1095 if (ch == 'V' && options.log_level >
1096 SYSLOG_LEVEL_QUIET)
1097 log_change_level(--options.log_level);
1098 if (ch == 'v' && options.log_level <
1099 SYSLOG_LEVEL_DEBUG3)
1100 log_change_level(++options.log_level);
1101 if ((r = sshbuf_putf(berr,
1102 "%c%c [LogLevel %s]\r\n",
1103 efc->escape_char, ch,
1104 log_level_name(options.log_level))) != 0)
1105 fatal_fr(r, "sshbuf_putf");
1106 continue;
1107
1108 case '&':
1109 if (c && c->ctl_chan != -1)
1110 goto noescape;
1111 /*
1112 * Detach the program (continue to serve
1113 * connections, but put in background and no
1114 * more new connections).
1115 */
1116 /* Restore tty modes. */
1117 leave_raw_mode(
1118 options.request_tty == REQUEST_TTY_FORCE);
1119
1120 /* Stop listening for new connections. */
1121 channel_stop_listening(ssh);
1122
1123 if ((r = sshbuf_putf(berr, "%c& "
1124 "[backgrounded]\n", efc->escape_char)) != 0)
1125 fatal_fr(r, "sshbuf_putf");
1126
1127 /* Fork into background. */
1128 pid = fork();
1129 if (pid == -1) {
1130 error("fork: %.100s", strerror(errno));
1131 continue;
1132 }
1133 if (pid != 0) { /* This is the parent. */
1134 /* The parent just exits. */
1135 exit(0);
1136 }
1137 /* The child continues serving connections. */
1138 /* fake EOF on stdin */
1139 if ((r = sshbuf_put_u8(bin, 4)) != 0)
1140 fatal_fr(r, "sshbuf_put_u8");
1141 return -1;
1142 case '?':
1143 print_escape_help(berr, efc->escape_char,
1144 (c && c->ctl_chan != -1),
1145 log_is_on_stderr());
1146 continue;
1147
1148 case '#':
1149 if ((r = sshbuf_putf(berr, "%c#\r\n",
1150 efc->escape_char)) != 0)
1151 fatal_fr(r, "sshbuf_putf");
1152 s = channel_open_message(ssh);
1153 if ((r = sshbuf_put(berr, s, strlen(s))) != 0)
1154 fatal_fr(r, "sshbuf_put");
1155 free(s);
1156 continue;
1157
1158 case 'C':
1159 if (c && c->ctl_chan != -1)
1160 goto noescape;
1161 if (options.enable_escape_commandline == 0) {
1162 if ((r = sshbuf_putf(berr,
1163 "commandline disabled\r\n")) != 0)
1164 fatal_fr(r, "sshbuf_putf");
1165 continue;
1166 }
1167 process_cmdline(ssh);
1168 continue;
1169
1170 default:
1171 if (ch != efc->escape_char) {
1172 if ((r = sshbuf_put_u8(bin,
1173 efc->escape_char)) != 0)
1174 fatal_fr(r, "sshbuf_put_u8");
1175 bytes++;
1176 }
1177 /* Escaped characters fall through here */
1178 break;
1179 }
1180 } else {
1181 /*
1182 * The previous character was not an escape char.
1183 * Check if this is an escape.
1184 */
1185 if (last_was_cr && ch == efc->escape_char) {
1186 /*
1187 * It is. Set the flag and continue to
1188 * next character.
1189 */
1190 efc->escape_pending = 1;
1191 continue;
1192 }
1193 }
1194
1195 /*
1196 * Normal character. Record whether it was a newline,
1197 * and append it to the buffer.
1198 */
1199 last_was_cr = (ch == '\r' || ch == '\n');
1200 if ((r = sshbuf_put_u8(bin, ch)) != 0)
1201 fatal_fr(r, "sshbuf_put_u8");
1202 bytes++;
1203 }
1204 return bytes;
1205 }
1206
1207 /*
1208 * Get packets from the connection input buffer, and process them as long as
1209 * there are packets available.
1210 *
1211 * Any unknown packets received during the actual
1212 * session cause the session to terminate. This is
1213 * intended to make debugging easier since no
1214 * confirmations are sent. Any compatible protocol
1215 * extensions must be negotiated during the
1216 * preparatory phase.
1217 */
1218
1219 static void
client_process_buffered_input_packets(struct ssh * ssh)1220 client_process_buffered_input_packets(struct ssh *ssh)
1221 {
1222 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending);
1223 }
1224
1225 /* scan buf[] for '~' before sending data to the peer */
1226
1227 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */
1228 void *
client_new_escape_filter_ctx(int escape_char)1229 client_new_escape_filter_ctx(int escape_char)
1230 {
1231 struct escape_filter_ctx *ret;
1232
1233 ret = xcalloc(1, sizeof(*ret));
1234 ret->escape_pending = 0;
1235 ret->escape_char = escape_char;
1236 return (void *)ret;
1237 }
1238
1239 /* Free the escape filter context on channel free */
1240 void
client_filter_cleanup(struct ssh * ssh,int cid,void * ctx)1241 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx)
1242 {
1243 free(ctx);
1244 }
1245
1246 int
client_simple_escape_filter(struct ssh * ssh,Channel * c,const char * buf,int len)1247 client_simple_escape_filter(struct ssh *ssh, Channel *c, const char *buf,
1248 int len)
1249 {
1250 if (c->extended_usage != CHAN_EXTENDED_WRITE)
1251 return 0;
1252
1253 return process_escapes(ssh, c, c->input, c->output, c->extended,
1254 buf, len);
1255 }
1256
1257 static void
client_channel_closed(struct ssh * ssh,int id,int force,void * arg)1258 client_channel_closed(struct ssh *ssh, int id, int force, void *arg)
1259 {
1260 channel_cancel_cleanup(ssh, id);
1261 session_closed = 1;
1262 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1263 }
1264
1265 /*
1266 * Implements the interactive session with the server. This is called after
1267 * the user has been authenticated, and a command has been started on the
1268 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character
1269 * used as an escape character for terminating or suspending the session.
1270 */
1271 int
client_loop(struct ssh * ssh,int have_pty,int escape_char_arg,int ssh2_chan_id)1272 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
1273 int ssh2_chan_id)
1274 {
1275 struct pollfd *pfd = NULL;
1276 u_int npfd_alloc = 0, npfd_active = 0;
1277 double start_time, total_time;
1278 int r, len;
1279 u_int64_t ibytes, obytes;
1280 int conn_in_ready, conn_out_ready;
1281
1282 debug("Entering interactive session.");
1283 session_ident = ssh2_chan_id;
1284
1285 #ifdef __OpenBSD__
1286 if (options.control_master &&
1287 !option_clear_or_none(options.control_path)) {
1288 debug("pledge: id");
1289 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty",
1290 NULL) == -1)
1291 fatal_f("pledge(): %s", strerror(errno));
1292
1293 } else if (options.forward_x11 || options.permit_local_command) {
1294 debug("pledge: exec");
1295 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty",
1296 NULL) == -1)
1297 fatal_f("pledge(): %s", strerror(errno));
1298
1299 } else if (options.update_hostkeys) {
1300 debug("pledge: filesystem");
1301 if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
1302 NULL) == -1)
1303 fatal_f("pledge(): %s", strerror(errno));
1304
1305 } else if (!option_clear_or_none(options.proxy_command) ||
1306 options.fork_after_authentication) {
1307 debug("pledge: proc");
1308 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
1309 fatal_f("pledge(): %s", strerror(errno));
1310
1311 } else {
1312 debug("pledge: network");
1313 if (pledge("stdio unix inet dns proc tty", NULL) == -1)
1314 fatal_f("pledge(): %s", strerror(errno));
1315 }
1316 #endif
1317
1318 /* might be able to tighten now */
1319 client_repledge();
1320
1321 start_time = monotime_double();
1322
1323 /* Initialize variables. */
1324 last_was_cr = 1;
1325 exit_status = -1;
1326 connection_in = ssh_packet_get_connection_in(ssh);
1327 connection_out = ssh_packet_get_connection_out(ssh);
1328
1329 quit_pending = 0;
1330
1331 /* Initialize buffer. */
1332 if ((stderr_buffer = sshbuf_new()) == NULL)
1333 fatal_f("sshbuf_new failed");
1334
1335 client_init_dispatch(ssh);
1336
1337 /*
1338 * Set signal handlers, (e.g. to restore non-blocking mode)
1339 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
1340 */
1341 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN)
1342 ssh_signal(SIGHUP, signal_handler);
1343 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN)
1344 ssh_signal(SIGINT, signal_handler);
1345 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN)
1346 ssh_signal(SIGQUIT, signal_handler);
1347 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN)
1348 ssh_signal(SIGTERM, signal_handler);
1349 ssh_signal(SIGWINCH, window_change_handler);
1350
1351 if (have_pty)
1352 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1353
1354 if (session_ident != -1) {
1355 if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
1356 channel_register_filter(ssh, session_ident,
1357 client_simple_escape_filter, NULL,
1358 client_filter_cleanup,
1359 client_new_escape_filter_ctx(
1360 escape_char_arg));
1361 }
1362 channel_register_cleanup(ssh, session_ident,
1363 client_channel_closed, 0);
1364 }
1365
1366 schedule_server_alive_check();
1367
1368 /* Main loop of the client for the interactive session mode. */
1369 while (!quit_pending) {
1370
1371 /* Process buffered packets sent by the server. */
1372 client_process_buffered_input_packets(ssh);
1373
1374 if (session_closed && !channel_still_open(ssh))
1375 break;
1376
1377 if (ssh_packet_is_rekeying(ssh)) {
1378 debug("rekeying in progress");
1379 } else if (need_rekeying) {
1380 /* manual rekey request */
1381 debug("need rekeying");
1382 if ((r = kex_start_rekex(ssh)) != 0)
1383 fatal_fr(r, "kex_start_rekex");
1384 need_rekeying = 0;
1385 } else {
1386 /*
1387 * Make packets from buffered channel data, and
1388 * enqueue them for sending to the server.
1389 */
1390 if (ssh_packet_not_very_much_data_to_write(ssh))
1391 channel_output_poll(ssh);
1392
1393 /*
1394 * Check if the window size has changed, and buffer a
1395 * message about it to the server if so.
1396 */
1397 client_check_window_change(ssh);
1398
1399 if (quit_pending)
1400 break;
1401 }
1402 /*
1403 * Wait until we have something to do (something becomes
1404 * available on one of the descriptors).
1405 */
1406 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc,
1407 &npfd_active, ssh_packet_is_rekeying(ssh),
1408 &conn_in_ready, &conn_out_ready);
1409
1410 if (quit_pending)
1411 break;
1412
1413 /* Do channel operations. */
1414 channel_after_poll(ssh, pfd, npfd_active);
1415
1416 /* Buffer input from the connection. */
1417 if (conn_in_ready)
1418 client_process_net_input(ssh);
1419
1420 if (quit_pending)
1421 break;
1422
1423 /* A timeout may have triggered rekeying */
1424 if ((r = ssh_packet_check_rekey(ssh)) != 0)
1425 fatal_fr(r, "cannot start rekeying");
1426
1427 /*
1428 * Send as much buffered packet data as possible to the
1429 * sender.
1430 */
1431 if (conn_out_ready) {
1432 if ((r = ssh_packet_write_poll(ssh)) < 0) {
1433 sshpkt_fatal(ssh, r,
1434 "%s: ssh_packet_write_poll", __func__);
1435 }
1436 }
1437
1438 /*
1439 * If we are a backgrounded control master, and the
1440 * timeout has expired without any active client
1441 * connections, then quit.
1442 */
1443 if (control_persist_exit_time > 0) {
1444 if (monotime() >= control_persist_exit_time) {
1445 debug("ControlPersist timeout expired");
1446 break;
1447 }
1448 }
1449 }
1450 free(pfd);
1451
1452 /* Terminate the session. */
1453
1454 /* Stop watching for window change. */
1455 ssh_signal(SIGWINCH, SIG_DFL);
1456
1457 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
1458 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 ||
1459 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 ||
1460 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */
1461 (r = sshpkt_send(ssh)) != 0 ||
1462 (r = ssh_packet_write_wait(ssh)) < 0)
1463 fatal_fr(r, "send disconnect");
1464
1465 channel_free_all(ssh);
1466
1467 if (have_pty)
1468 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1469
1470 /*
1471 * If there was no shell or command requested, there will be no remote
1472 * exit status to be returned. In that case, clear error code if the
1473 * connection was deliberately terminated at this end.
1474 */
1475 if (options.session_type == SESSION_TYPE_NONE &&
1476 received_signal == SIGTERM) {
1477 received_signal = 0;
1478 exit_status = 0;
1479 }
1480
1481 if (received_signal) {
1482 verbose("Killed by signal %d.", (int) received_signal);
1483 cleanup_exit(255);
1484 }
1485
1486 /*
1487 * In interactive mode (with pseudo tty) display a message indicating
1488 * that the connection has been closed.
1489 */
1490 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO)
1491 quit_message("Connection to %s closed.", host);
1492
1493 /* Output any buffered data for stderr. */
1494 if (sshbuf_len(stderr_buffer) > 0) {
1495 len = atomicio(vwrite, fileno(stderr),
1496 sshbuf_mutable_ptr(stderr_buffer),
1497 sshbuf_len(stderr_buffer));
1498 if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer))
1499 error("Write failed flushing stderr buffer.");
1500 else if ((r = sshbuf_consume(stderr_buffer, len)) != 0)
1501 fatal_fr(r, "sshbuf_consume");
1502 }
1503
1504 /* Clear and free any buffers. */
1505 sshbuf_free(stderr_buffer);
1506
1507 /* Report bytes transferred, and transfer rates. */
1508 total_time = monotime_double() - start_time;
1509 ssh_packet_get_bytes(ssh, &ibytes, &obytes);
1510 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
1511 (unsigned long long)obytes, (unsigned long long)ibytes, total_time);
1512 if (total_time > 0)
1513 verbose("Bytes per second: sent %.1f, received %.1f",
1514 obytes / total_time, ibytes / total_time);
1515 /* Return the exit status of the program. */
1516 debug("Exit status %d", exit_status);
1517 return exit_status;
1518 }
1519
1520 /*********/
1521
1522 static Channel *
client_request_forwarded_tcpip(struct ssh * ssh,const char * request_type,int rchan,u_int rwindow,u_int rmaxpack)1523 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
1524 int rchan, u_int rwindow, u_int rmaxpack)
1525 {
1526 Channel *c = NULL;
1527 struct sshbuf *b = NULL;
1528 char *listen_address, *originator_address;
1529 u_int listen_port, originator_port;
1530 int r;
1531
1532 /* Get rest of the packet */
1533 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 ||
1534 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 ||
1535 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 ||
1536 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
1537 (r = sshpkt_get_end(ssh)) != 0)
1538 fatal_fr(r, "parse packet");
1539
1540 debug_f("listen %s port %d, originator %s port %d",
1541 listen_address, listen_port, originator_address, originator_port);
1542
1543 if (listen_port > 0xffff)
1544 error_f("invalid listen port");
1545 else if (originator_port > 0xffff)
1546 error_f("invalid originator port");
1547 else {
1548 c = channel_connect_by_listen_address(ssh,
1549 listen_address, listen_port, "forwarded-tcpip",
1550 originator_address);
1551 }
1552
1553 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1554 if ((b = sshbuf_new()) == NULL) {
1555 error_f("alloc reply");
1556 goto out;
1557 }
1558 /* reconstruct and send to muxclient */
1559 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
1560 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1561 (r = sshbuf_put_cstring(b, request_type)) != 0 ||
1562 (r = sshbuf_put_u32(b, rchan)) != 0 ||
1563 (r = sshbuf_put_u32(b, rwindow)) != 0 ||
1564 (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
1565 (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
1566 (r = sshbuf_put_u32(b, listen_port)) != 0 ||
1567 (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
1568 (r = sshbuf_put_u32(b, originator_port)) != 0 ||
1569 (r = sshbuf_put_stringb(c->output, b)) != 0) {
1570 error_fr(r, "compose for muxclient");
1571 goto out;
1572 }
1573 }
1574
1575 out:
1576 sshbuf_free(b);
1577 free(originator_address);
1578 free(listen_address);
1579 return c;
1580 }
1581
1582 static Channel *
client_request_forwarded_streamlocal(struct ssh * ssh,const char * request_type,int rchan)1583 client_request_forwarded_streamlocal(struct ssh *ssh,
1584 const char *request_type, int rchan)
1585 {
1586 Channel *c = NULL;
1587 char *listen_path;
1588 int r;
1589
1590 /* Get the remote path. */
1591 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 ||
1592 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */
1593 (r = sshpkt_get_end(ssh)) != 0)
1594 fatal_fr(r, "parse packet");
1595
1596 debug_f("request: %s", listen_path);
1597
1598 c = channel_connect_by_listen_path(ssh, listen_path,
1599 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
1600 free(listen_path);
1601 return c;
1602 }
1603
1604 static Channel *
client_request_x11(struct ssh * ssh,const char * request_type,int rchan)1605 client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
1606 {
1607 Channel *c = NULL;
1608 char *originator;
1609 u_int originator_port;
1610 int r, sock;
1611
1612 if (!options.forward_x11) {
1613 error("Warning: ssh server tried X11 forwarding.");
1614 error("Warning: this is probably a break-in attempt by a "
1615 "malicious server.");
1616 return NULL;
1617 }
1618 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) {
1619 verbose("Rejected X11 connection after ForwardX11Timeout "
1620 "expired");
1621 return NULL;
1622 }
1623 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
1624 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
1625 (r = sshpkt_get_end(ssh)) != 0)
1626 fatal_fr(r, "parse packet");
1627 /* XXX check permission */
1628 /* XXX range check originator port? */
1629 debug("client_request_x11: request from %s %u", originator,
1630 originator_port);
1631 free(originator);
1632 sock = x11_connect_display(ssh);
1633 if (sock < 0)
1634 return NULL;
1635 /* again is this really necessary for X11? */
1636 if (options.hpn_disabled)
1637 c = channel_new(ssh, "x11",
1638 SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1639 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1640 else
1641 c = channel_new(ssh, "x11",
1642 SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1643 options.hpn_buffer_size, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1644 c->force_drain = 1;
1645 return c;
1646 }
1647
1648 static Channel *
client_request_agent(struct ssh * ssh,const char * request_type,int rchan)1649 client_request_agent(struct ssh *ssh, const char *request_type, int rchan)
1650 {
1651 Channel *c = NULL;
1652 int r, sock;
1653
1654 if (!options.forward_agent) {
1655 error("Warning: ssh server tried agent forwarding.");
1656 error("Warning: this is probably a break-in attempt by a "
1657 "malicious server.");
1658 return NULL;
1659 }
1660 if (forward_agent_sock_path == NULL) {
1661 r = ssh_get_authentication_socket(&sock);
1662 } else {
1663 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock);
1664 }
1665 if (r != 0) {
1666 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1667 debug_fr(r, "ssh_get_authentication_socket");
1668 return NULL;
1669 }
1670 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey,
1671 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0)
1672 debug_f("bound agent to hostkey");
1673 else
1674 debug2_fr(r, "ssh_agent_bind_hostkey");
1675
1676 if (options.hpn_disabled)
1677 c = channel_new(ssh, "authentication agent connection",
1678 SSH_CHANNEL_OPEN, sock, sock, -1,
1679 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
1680 "authentication agent connection", 1);
1681 else
1682 c = channel_new(ssh, "authentication agent connection",
1683 SSH_CHANNEL_OPEN, sock, sock, -1,
1684 options.hpn_buffer_size, options.hpn_buffer_size, 0,
1685 "authentication agent connection", 1);
1686 c->force_drain = 1;
1687 return c;
1688 }
1689
1690 char *
client_request_tun_fwd(struct ssh * ssh,int tun_mode,int local_tun,int remote_tun,channel_open_fn * cb,void * cbctx)1691 client_request_tun_fwd(struct ssh *ssh, int tun_mode,
1692 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx)
1693 {
1694 Channel *c;
1695 int r, fd;
1696 char *ifname = NULL;
1697
1698 if (tun_mode == SSH_TUNMODE_NO)
1699 return 0;
1700
1701 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);
1702
1703 /* Open local tunnel device */
1704 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) {
1705 error("Tunnel device open failed.");
1706 return NULL;
1707 }
1708 debug("Tunnel forwarding using interface %s", ifname);
1709
1710 if(options.hpn_disabled)
1711 c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1712 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1713 else
1714 c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1715 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1716 c->datagram = 1;
1717
1718 if (cb != NULL)
1719 channel_register_open_confirm(ssh, c->self, cb, cbctx);
1720
1721 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1722 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 ||
1723 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
1724 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 ||
1725 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
1726 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 ||
1727 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 ||
1728 (r = sshpkt_send(ssh)) != 0)
1729 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
1730
1731 return ifname;
1732 }
1733
1734 /* XXXX move to generic input handler */
1735 static int
client_input_channel_open(int type,u_int32_t seq,struct ssh * ssh)1736 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
1737 {
1738 Channel *c = NULL;
1739 char *ctype = NULL;
1740 int r;
1741 u_int rchan;
1742 size_t len;
1743 u_int rmaxpack, rwindow;
1744
1745 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 ||
1746 (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
1747 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
1748 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
1749 goto out;
1750
1751 debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
1752 ctype, rchan, rwindow, rmaxpack);
1753
1754 if (strcmp(ctype, "forwarded-tcpip") == 0) {
1755 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow,
1756 rmaxpack);
1757 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
1758 c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
1759 } else if (strcmp(ctype, "x11") == 0) {
1760 c = client_request_x11(ssh, ctype, rchan);
1761 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
1762 c = client_request_agent(ssh, ctype, rchan);
1763 }
1764 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1765 debug3("proxied to downstream: %s", ctype);
1766 } else if (c != NULL) {
1767 debug("confirm %s", ctype);
1768 c->remote_id = rchan;
1769 c->have_remote_id = 1;
1770 c->remote_window = rwindow;
1771 c->remote_maxpacket = rmaxpack;
1772 if (c->type != SSH_CHANNEL_CONNECTING) {
1773 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
1774 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
1775 (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
1776 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
1777 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
1778 (r = sshpkt_send(ssh)) != 0)
1779 sshpkt_fatal(ssh, r, "%s: send reply", __func__);
1780 }
1781 } else {
1782 debug("failure %s", ctype);
1783 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
1784 (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
1785 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 ||
1786 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 ||
1787 (r = sshpkt_put_cstring(ssh, "")) != 0 ||
1788 (r = sshpkt_send(ssh)) != 0)
1789 sshpkt_fatal(ssh, r, "%s: send failure", __func__);
1790 }
1791 r = 0;
1792 out:
1793 free(ctype);
1794 return r;
1795 }
1796
1797 static int
client_input_channel_req(int type,u_int32_t seq,struct ssh * ssh)1798 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
1799 {
1800 Channel *c = NULL;
1801 char *rtype = NULL;
1802 u_char reply;
1803 u_int id, exitval;
1804 int r, success = 0;
1805
1806 if ((r = sshpkt_get_u32(ssh, &id)) != 0)
1807 return r;
1808 if (id <= INT_MAX)
1809 c = channel_lookup(ssh, id);
1810 if (channel_proxy_upstream(c, type, seq, ssh))
1811 return 0;
1812 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
1813 (r = sshpkt_get_u8(ssh, &reply)) != 0)
1814 goto out;
1815
1816 debug("client_input_channel_req: channel %u rtype %s reply %d",
1817 id, rtype, reply);
1818
1819 if (c == NULL) {
1820 error("client_input_channel_req: channel %d: "
1821 "unknown channel", id);
1822 } else if (strcmp(rtype, "eow@openssh.com") == 0) {
1823 if ((r = sshpkt_get_end(ssh)) != 0)
1824 goto out;
1825 chan_rcvd_eow(ssh, c);
1826 } else if (strcmp(rtype, "exit-status") == 0) {
1827 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0)
1828 goto out;
1829 if (c->ctl_chan != -1) {
1830 mux_exit_message(ssh, c, exitval);
1831 success = 1;
1832 } else if ((int)id == session_ident) {
1833 /* Record exit value of local session */
1834 success = 1;
1835 exit_status = exitval;
1836 } else {
1837 /* Probably for a mux channel that has already closed */
1838 debug_f("no sink for exit-status on channel %d",
1839 id);
1840 }
1841 if ((r = sshpkt_get_end(ssh)) != 0)
1842 goto out;
1843 }
1844 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
1845 if (!c->have_remote_id)
1846 fatal_f("channel %d: no remote_id", c->self);
1847 if ((r = sshpkt_start(ssh, success ?
1848 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
1849 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
1850 (r = sshpkt_send(ssh)) != 0)
1851 sshpkt_fatal(ssh, r, "%s: send failure", __func__);
1852 }
1853 r = 0;
1854 out:
1855 free(rtype);
1856 return r;
1857 }
1858
1859 struct hostkeys_update_ctx {
1860 /* The hostname and (optionally) IP address string for the server */
1861 char *host_str, *ip_str;
1862
1863 /*
1864 * Keys received from the server and a flag for each indicating
1865 * whether they already exist in known_hosts.
1866 * keys_match is filled in by hostkeys_find() and later (for new
1867 * keys) by client_global_hostkeys_prove_confirm().
1868 */
1869 struct sshkey **keys;
1870 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */
1871 int *keys_verified; /* flag for new keys verified by server */
1872 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */
1873
1874 /*
1875 * Keys that are in known_hosts, but were not present in the update
1876 * from the server (i.e. scheduled to be deleted).
1877 * Filled in by hostkeys_find().
1878 */
1879 struct sshkey **old_keys;
1880 size_t nold;
1881
1882 /* Various special cases. */
1883 int complex_hostspec; /* wildcard or manual pattern-list host name */
1884 int ca_available; /* saw CA key for this host */
1885 int old_key_seen; /* saw old key with other name/addr */
1886 int other_name_seen; /* saw key with other name/addr */
1887 };
1888
1889 static void
hostkeys_update_ctx_free(struct hostkeys_update_ctx * ctx)1890 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
1891 {
1892 size_t i;
1893
1894 if (ctx == NULL)
1895 return;
1896 for (i = 0; i < ctx->nkeys; i++)
1897 sshkey_free(ctx->keys[i]);
1898 free(ctx->keys);
1899 free(ctx->keys_match);
1900 free(ctx->keys_verified);
1901 for (i = 0; i < ctx->nold; i++)
1902 sshkey_free(ctx->old_keys[i]);
1903 free(ctx->old_keys);
1904 free(ctx->host_str);
1905 free(ctx->ip_str);
1906 free(ctx);
1907 }
1908
1909 /*
1910 * Returns non-zero if a known_hosts hostname list is not of a form that
1911 * can be handled by UpdateHostkeys. These include wildcard hostnames and
1912 * hostnames lists that do not follow the form host[,ip].
1913 */
1914 static int
hostspec_is_complex(const char * hosts)1915 hostspec_is_complex(const char *hosts)
1916 {
1917 char *cp;
1918
1919 /* wildcard */
1920 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL)
1921 return 1;
1922 /* single host/ip = ok */
1923 if ((cp = strchr(hosts, ',')) == NULL)
1924 return 0;
1925 /* more than two entries on the line */
1926 if (strchr(cp + 1, ',') != NULL)
1927 return 1;
1928 /* XXX maybe parse cp+1 and ensure it is an IP? */
1929 return 0;
1930 }
1931
1932 /* callback to search for ctx->keys in known_hosts */
1933 static int
hostkeys_find(struct hostkey_foreach_line * l,void * _ctx)1934 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
1935 {
1936 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
1937 size_t i;
1938 struct sshkey **tmp;
1939
1940 if (l->key == NULL)
1941 return 0;
1942 if (l->status != HKF_STATUS_MATCHED) {
1943 /* Record if one of the keys appears on a non-matching line */
1944 for (i = 0; i < ctx->nkeys; i++) {
1945 if (sshkey_equal(l->key, ctx->keys[i])) {
1946 ctx->other_name_seen = 1;
1947 debug3_f("found %s key under different "
1948 "name/addr at %s:%ld",
1949 sshkey_ssh_name(ctx->keys[i]),
1950 l->path, l->linenum);
1951 return 0;
1952 }
1953 }
1954 return 0;
1955 }
1956 /* Don't proceed if revocation or CA markers are present */
1957 /* XXX relax this */
1958 if (l->marker != MRK_NONE) {
1959 debug3_f("hostkeys file %s:%ld has CA/revocation marker",
1960 l->path, l->linenum);
1961 ctx->complex_hostspec = 1;
1962 return 0;
1963 }
1964
1965 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */
1966 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) {
1967 if ((l->match & HKF_MATCH_HOST) == 0) {
1968 /* Record if address matched a different hostname. */
1969 ctx->other_name_seen = 1;
1970 debug3_f("found address %s against different hostname "
1971 "at %s:%ld", ctx->ip_str, l->path, l->linenum);
1972 return 0;
1973 } else if ((l->match & HKF_MATCH_IP) == 0) {
1974 /* Record if hostname matched a different address. */
1975 ctx->other_name_seen = 1;
1976 debug3_f("found hostname %s against different address "
1977 "at %s:%ld", ctx->host_str, l->path, l->linenum);
1978 }
1979 }
1980
1981 /*
1982 * UpdateHostkeys is skipped for wildcard host names and hostnames
1983 * that contain more than two entries (ssh never writes these).
1984 */
1985 if (hostspec_is_complex(l->hosts)) {
1986 debug3_f("hostkeys file %s:%ld complex host specification",
1987 l->path, l->linenum);
1988 ctx->complex_hostspec = 1;
1989 return 0;
1990 }
1991
1992 /* Mark off keys we've already seen for this host */
1993 for (i = 0; i < ctx->nkeys; i++) {
1994 if (!sshkey_equal(l->key, ctx->keys[i]))
1995 continue;
1996 debug3_f("found %s key at %s:%ld",
1997 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
1998 ctx->keys_match[i] |= l->match;
1999 return 0;
2000 }
2001 /* This line contained a key that not offered by the server */
2002 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key),
2003 l->path, l->linenum);
2004 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1,
2005 sizeof(*ctx->old_keys))) == NULL)
2006 fatal_f("recallocarray failed nold = %zu", ctx->nold);
2007 ctx->old_keys = tmp;
2008 ctx->old_keys[ctx->nold++] = l->key;
2009 l->key = NULL;
2010
2011 return 0;
2012 }
2013
2014 /* callback to search for ctx->old_keys in known_hosts under other names */
2015 static int
hostkeys_check_old(struct hostkey_foreach_line * l,void * _ctx)2016 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx)
2017 {
2018 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2019 size_t i;
2020 int hashed;
2021
2022 /* only care about lines that *don't* match the active host spec */
2023 if (l->status == HKF_STATUS_MATCHED || l->key == NULL)
2024 return 0;
2025
2026 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED);
2027 for (i = 0; i < ctx->nold; i++) {
2028 if (!sshkey_equal(l->key, ctx->old_keys[i]))
2029 continue;
2030 debug3_f("found deprecated %s key at %s:%ld as %s",
2031 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum,
2032 hashed ? "[HASHED]" : l->hosts);
2033 ctx->old_key_seen = 1;
2034 break;
2035 }
2036 return 0;
2037 }
2038
2039 /*
2040 * Check known_hosts files for deprecated keys under other names. Returns 0
2041 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys
2042 * exist under names other than the active hostname/IP.
2043 */
2044 static int
check_old_keys_othernames(struct hostkeys_update_ctx * ctx)2045 check_old_keys_othernames(struct hostkeys_update_ctx *ctx)
2046 {
2047 size_t i;
2048 int r;
2049
2050 debug2_f("checking for %zu deprecated keys", ctx->nold);
2051 for (i = 0; i < options.num_user_hostfiles; i++) {
2052 debug3_f("searching %s for %s / %s",
2053 options.user_hostfiles[i], ctx->host_str,
2054 ctx->ip_str ? ctx->ip_str : "(none)");
2055 if ((r = hostkeys_foreach(options.user_hostfiles[i],
2056 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str,
2057 HKF_WANT_PARSE_KEY, 0)) != 0) {
2058 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
2059 debug_f("hostkeys file %s does not exist",
2060 options.user_hostfiles[i]);
2061 continue;
2062 }
2063 error_fr(r, "hostkeys_foreach failed for %s",
2064 options.user_hostfiles[i]);
2065 return -1;
2066 }
2067 }
2068 return 0;
2069 }
2070
2071 static void
hostkey_change_preamble(LogLevel loglevel)2072 hostkey_change_preamble(LogLevel loglevel)
2073 {
2074 do_log2(loglevel, "The server has updated its host keys.");
2075 do_log2(loglevel, "These changes were verified by the server's "
2076 "existing trusted key.");
2077 }
2078
2079 static void
update_known_hosts(struct hostkeys_update_ctx * ctx)2080 update_known_hosts(struct hostkeys_update_ctx *ctx)
2081 {
2082 int r, was_raw = 0, first = 1;
2083 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK;
2084 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
2085 char *fp, *response;
2086 size_t i;
2087 struct stat sb;
2088
2089 for (i = 0; i < ctx->nkeys; i++) {
2090 if (!ctx->keys_verified[i])
2091 continue;
2092 if ((fp = sshkey_fingerprint(ctx->keys[i],
2093 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2094 fatal_f("sshkey_fingerprint failed");
2095 if (first && asking)
2096 hostkey_change_preamble(loglevel);
2097 do_log2(loglevel, "Learned new hostkey: %s %s",
2098 sshkey_type(ctx->keys[i]), fp);
2099 first = 0;
2100 free(fp);
2101 }
2102 for (i = 0; i < ctx->nold; i++) {
2103 if ((fp = sshkey_fingerprint(ctx->old_keys[i],
2104 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2105 fatal_f("sshkey_fingerprint failed");
2106 if (first && asking)
2107 hostkey_change_preamble(loglevel);
2108 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
2109 sshkey_type(ctx->old_keys[i]), fp);
2110 first = 0;
2111 free(fp);
2112 }
2113 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
2114 if (get_saved_tio() != NULL) {
2115 leave_raw_mode(1);
2116 was_raw = 1;
2117 }
2118 response = NULL;
2119 for (i = 0; !quit_pending && i < 3; i++) {
2120 free(response);
2121 response = read_passphrase("Accept updated hostkeys? "
2122 "(yes/no): ", RP_ECHO);
2123 if (response != NULL && strcasecmp(response, "yes") == 0)
2124 break;
2125 else if (quit_pending || response == NULL ||
2126 strcasecmp(response, "no") == 0) {
2127 options.update_hostkeys = 0;
2128 break;
2129 } else {
2130 do_log2(loglevel, "Please enter "
2131 "\"yes\" or \"no\"");
2132 }
2133 }
2134 if (quit_pending || i >= 3 || response == NULL)
2135 options.update_hostkeys = 0;
2136 free(response);
2137 if (was_raw)
2138 enter_raw_mode(1);
2139 }
2140 if (options.update_hostkeys == 0)
2141 return;
2142 /*
2143 * Now that all the keys are verified, we can go ahead and replace
2144 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
2145 * cancel the operation).
2146 */
2147 for (i = 0; i < options.num_user_hostfiles; i++) {
2148 /*
2149 * NB. keys are only added to hostfiles[0], for the rest we
2150 * just delete the hostname entries.
2151 */
2152 if (stat(options.user_hostfiles[i], &sb) != 0) {
2153 if (errno == ENOENT) {
2154 debug_f("known hosts file %s does not "
2155 "exist", options.user_hostfiles[i]);
2156 } else {
2157 error_f("known hosts file %s "
2158 "inaccessible: %s",
2159 options.user_hostfiles[i], strerror(errno));
2160 }
2161 continue;
2162 }
2163 if ((r = hostfile_replace_entries(options.user_hostfiles[i],
2164 ctx->host_str, ctx->ip_str,
2165 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0,
2166 options.hash_known_hosts, 0,
2167 options.fingerprint_hash)) != 0) {
2168 error_fr(r, "hostfile_replace_entries failed for %s",
2169 options.user_hostfiles[i]);
2170 }
2171 }
2172 }
2173
2174 static void
client_global_hostkeys_prove_confirm(struct ssh * ssh,int type,u_int32_t seq,void * _ctx)2175 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type,
2176 u_int32_t seq, void *_ctx)
2177 {
2178 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2179 size_t i, ndone;
2180 struct sshbuf *signdata;
2181 int r, plaintype;
2182 const u_char *sig;
2183 const char *rsa_kexalg = NULL;
2184 char *alg = NULL;
2185 size_t siglen;
2186
2187 if (ctx->nnew == 0)
2188 fatal_f("ctx->nnew == 0"); /* sanity */
2189 if (type != SSH2_MSG_REQUEST_SUCCESS) {
2190 error("Server failed to confirm ownership of "
2191 "private host keys");
2192 hostkeys_update_ctx_free(ctx);
2193 return;
2194 }
2195 if (sshkey_type_plain(sshkey_type_from_name(
2196 ssh->kex->hostkey_alg)) == KEY_RSA)
2197 rsa_kexalg = ssh->kex->hostkey_alg;
2198 if ((signdata = sshbuf_new()) == NULL)
2199 fatal_f("sshbuf_new failed");
2200 /*
2201 * Expect a signature for each of the ctx->nnew private keys we
2202 * haven't seen before. They will be in the same order as the
2203 * ctx->keys where the corresponding ctx->keys_match[i] == 0.
2204 */
2205 for (ndone = i = 0; i < ctx->nkeys; i++) {
2206 if (ctx->keys_match[i])
2207 continue;
2208 plaintype = sshkey_type_plain(ctx->keys[i]->type);
2209 /* Prepare data to be signed: session ID, unique string, key */
2210 sshbuf_reset(signdata);
2211 if ( (r = sshbuf_put_cstring(signdata,
2212 "hostkeys-prove-00@openssh.com")) != 0 ||
2213 (r = sshbuf_put_stringb(signdata,
2214 ssh->kex->session_id)) != 0 ||
2215 (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
2216 fatal_fr(r, "compose signdata");
2217 /* Extract and verify signature */
2218 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
2219 error_fr(r, "parse sig");
2220 goto out;
2221 }
2222 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) {
2223 error_fr(r, "server gave unintelligible signature "
2224 "for %s key %zu", sshkey_type(ctx->keys[i]), i);
2225 goto out;
2226 }
2227 /*
2228 * Special case for RSA keys: if a RSA hostkey was negotiated,
2229 * then use its signature type for verification of RSA hostkey
2230 * proofs. Otherwise, accept only RSA-SHA256/512 signatures.
2231 */
2232 if (plaintype == KEY_RSA && rsa_kexalg == NULL &&
2233 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) {
2234 debug_f("server used untrusted RSA signature algorithm "
2235 "%s for key %zu, disregarding", alg, i);
2236 free(alg);
2237 /* zap the key from the list */
2238 sshkey_free(ctx->keys[i]);
2239 ctx->keys[i] = NULL;
2240 ndone++;
2241 continue;
2242 }
2243 debug3_f("verify %s key %zu using sigalg %s",
2244 sshkey_type(ctx->keys[i]), i, alg);
2245 free(alg);
2246 if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
2247 sshbuf_ptr(signdata), sshbuf_len(signdata),
2248 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) {
2249 error_fr(r, "server gave bad signature for %s key %zu",
2250 sshkey_type(ctx->keys[i]), i);
2251 goto out;
2252 }
2253 /* Key is good. Mark it as 'seen' */
2254 ctx->keys_verified[i] = 1;
2255 ndone++;
2256 }
2257 /* Shouldn't happen */
2258 if (ndone != ctx->nnew)
2259 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew);
2260 if ((r = sshpkt_get_end(ssh)) != 0) {
2261 error_f("protocol error");
2262 goto out;
2263 }
2264
2265 /* Make the edits to known_hosts */
2266 update_known_hosts(ctx);
2267 out:
2268 hostkeys_update_ctx_free(ctx);
2269 hostkeys_update_complete = 1;
2270 client_repledge();
2271 }
2272
2273 /*
2274 * Returns non-zero if the key is accepted by HostkeyAlgorithms.
2275 * Made slightly less trivial by the multiple RSA signature algorithm names.
2276 */
2277 static int
key_accepted_by_hostkeyalgs(const struct sshkey * key)2278 key_accepted_by_hostkeyalgs(const struct sshkey *key)
2279 {
2280 const char *ktype = sshkey_ssh_name(key);
2281 const char *hostkeyalgs = options.hostkeyalgorithms;
2282
2283 if (key == NULL || key->type == KEY_UNSPEC)
2284 return 0;
2285 if (key->type == KEY_RSA &&
2286 (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 ||
2287 match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1))
2288 return 1;
2289 return match_pattern_list(ktype, hostkeyalgs, 0) == 1;
2290 }
2291
2292 /*
2293 * Handle hostkeys-00@openssh.com global request to inform the client of all
2294 * the server's hostkeys. The keys are checked against the user's
2295 * HostkeyAlgorithms preference before they are accepted.
2296 */
2297 static int
client_input_hostkeys(struct ssh * ssh)2298 client_input_hostkeys(struct ssh *ssh)
2299 {
2300 const u_char *blob = NULL;
2301 size_t i, len = 0;
2302 struct sshbuf *buf = NULL;
2303 struct sshkey *key = NULL, **tmp;
2304 int r, prove_sent = 0;
2305 char *fp;
2306 static int hostkeys_seen = 0; /* XXX use struct ssh */
2307 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
2308 struct hostkeys_update_ctx *ctx = NULL;
2309 u_int want;
2310
2311 if (hostkeys_seen)
2312 fatal_f("server already sent hostkeys");
2313 if (!can_update_hostkeys())
2314 return 1;
2315 hostkeys_seen = 1;
2316
2317 ctx = xcalloc(1, sizeof(*ctx));
2318 while (ssh_packet_remaining(ssh) > 0) {
2319 sshkey_free(key);
2320 key = NULL;
2321 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
2322 error_fr(r, "parse key");
2323 goto out;
2324 }
2325 if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
2326 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ?
2327 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR,
2328 "convert key");
2329 continue;
2330 }
2331 fp = sshkey_fingerprint(key, options.fingerprint_hash,
2332 SSH_FP_DEFAULT);
2333 debug3_f("received %s key %s", sshkey_type(key), fp);
2334 free(fp);
2335
2336 if (!key_accepted_by_hostkeyalgs(key)) {
2337 debug3_f("%s key not permitted by "
2338 "HostkeyAlgorithms", sshkey_ssh_name(key));
2339 continue;
2340 }
2341 /* Skip certs */
2342 if (sshkey_is_cert(key)) {
2343 debug3_f("%s key is a certificate; skipping",
2344 sshkey_ssh_name(key));
2345 continue;
2346 }
2347 /* Ensure keys are unique */
2348 for (i = 0; i < ctx->nkeys; i++) {
2349 if (sshkey_equal(key, ctx->keys[i])) {
2350 error_f("received duplicated %s host key",
2351 sshkey_ssh_name(key));
2352 goto out;
2353 }
2354 }
2355 /* Key is good, record it */
2356 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1,
2357 sizeof(*ctx->keys))) == NULL)
2358 fatal_f("recallocarray failed nkeys = %zu",
2359 ctx->nkeys);
2360 ctx->keys = tmp;
2361 ctx->keys[ctx->nkeys++] = key;
2362 key = NULL;
2363 }
2364
2365 if (ctx->nkeys == 0) {
2366 debug_f("server sent no hostkeys");
2367 goto out;
2368 }
2369
2370 if ((ctx->keys_match = calloc(ctx->nkeys,
2371 sizeof(*ctx->keys_match))) == NULL ||
2372 (ctx->keys_verified = calloc(ctx->nkeys,
2373 sizeof(*ctx->keys_verified))) == NULL)
2374 fatal_f("calloc failed");
2375
2376 get_hostfile_hostname_ipaddr(host,
2377 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
2378 options.port, &ctx->host_str,
2379 options.check_host_ip ? &ctx->ip_str : NULL);
2380
2381 /* Find which keys we already know about. */
2382 for (i = 0; i < options.num_user_hostfiles; i++) {
2383 debug_f("searching %s for %s / %s",
2384 options.user_hostfiles[i], ctx->host_str,
2385 ctx->ip_str ? ctx->ip_str : "(none)");
2386 if ((r = hostkeys_foreach(options.user_hostfiles[i],
2387 hostkeys_find, ctx, ctx->host_str, ctx->ip_str,
2388 HKF_WANT_PARSE_KEY, 0)) != 0) {
2389 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
2390 debug_f("hostkeys file %s does not exist",
2391 options.user_hostfiles[i]);
2392 continue;
2393 }
2394 error_fr(r, "hostkeys_foreach failed for %s",
2395 options.user_hostfiles[i]);
2396 goto out;
2397 }
2398 }
2399
2400 /* Figure out if we have any new keys to add */
2401 ctx->nnew = ctx->nincomplete = 0;
2402 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0);
2403 for (i = 0; i < ctx->nkeys; i++) {
2404 if (ctx->keys_match[i] == 0)
2405 ctx->nnew++;
2406 if ((ctx->keys_match[i] & want) != want)
2407 ctx->nincomplete++;
2408 }
2409
2410 debug3_f("%zu server keys: %zu new, %zu retained, "
2411 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew,
2412 ctx->nkeys - ctx->nnew - ctx->nincomplete,
2413 ctx->nincomplete, ctx->nold);
2414
2415 if (ctx->nnew == 0 && ctx->nold == 0) {
2416 debug_f("no new or deprecated keys from server");
2417 goto out;
2418 }
2419
2420 /* Various reasons why we cannot proceed with the update */
2421 if (ctx->complex_hostspec) {
2422 debug_f("CA/revocation marker, manual host list or wildcard "
2423 "host pattern found, skipping UserKnownHostsFile update");
2424 goto out;
2425 }
2426 if (ctx->other_name_seen) {
2427 debug_f("host key found matching a different name/address, "
2428 "skipping UserKnownHostsFile update");
2429 goto out;
2430 }
2431 /*
2432 * If removing keys, check whether they appear under different
2433 * names/addresses and refuse to proceed if they do. This avoids
2434 * cases such as hosts with multiple names becoming inconsistent
2435 * with regards to CheckHostIP entries.
2436 * XXX UpdateHostkeys=force to override this (and other) checks?
2437 */
2438 if (ctx->nold != 0) {
2439 if (check_old_keys_othernames(ctx) != 0)
2440 goto out; /* error already logged */
2441 if (ctx->old_key_seen) {
2442 debug_f("key(s) for %s%s%s exist under other names; "
2443 "skipping UserKnownHostsFile update",
2444 ctx->host_str, ctx->ip_str == NULL ? "" : ",",
2445 ctx->ip_str == NULL ? "" : ctx->ip_str);
2446 goto out;
2447 }
2448 }
2449
2450 if (ctx->nnew == 0) {
2451 /*
2452 * We have some keys to remove or fix matching for.
2453 * We can proceed to do this without requiring a fresh proof
2454 * from the server.
2455 */
2456 update_known_hosts(ctx);
2457 goto out;
2458 }
2459 /*
2460 * We have received previously-unseen keys from the server.
2461 * Ask the server to confirm ownership of the private halves.
2462 */
2463 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew);
2464 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2465 (r = sshpkt_put_cstring(ssh,
2466 "hostkeys-prove-00@openssh.com")) != 0 ||
2467 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
2468 fatal_fr(r, "prepare hostkeys-prove");
2469 if ((buf = sshbuf_new()) == NULL)
2470 fatal_f("sshbuf_new");
2471 for (i = 0; i < ctx->nkeys; i++) {
2472 if (ctx->keys_match[i])
2473 continue;
2474 sshbuf_reset(buf);
2475 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 ||
2476 (r = sshpkt_put_stringb(ssh, buf)) != 0)
2477 fatal_fr(r, "assemble hostkeys-prove");
2478 }
2479 if ((r = sshpkt_send(ssh)) != 0)
2480 fatal_fr(r, "send hostkeys-prove");
2481 client_register_global_confirm(
2482 client_global_hostkeys_prove_confirm, ctx);
2483 ctx = NULL; /* will be freed in callback */
2484 prove_sent = 1;
2485
2486 /* Success */
2487 out:
2488 hostkeys_update_ctx_free(ctx);
2489 sshkey_free(key);
2490 sshbuf_free(buf);
2491 if (!prove_sent) {
2492 /* UpdateHostkeys handling completed */
2493 hostkeys_update_complete = 1;
2494 client_repledge();
2495 }
2496 /*
2497 * NB. Return success for all cases. The server doesn't need to know
2498 * what the client does with its hosts file.
2499 */
2500 return 1;
2501 }
2502
2503 static int
client_input_global_request(int type,u_int32_t seq,struct ssh * ssh)2504 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
2505 {
2506 char *rtype;
2507 u_char want_reply;
2508 int r, success = 0;
2509
2510 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
2511 (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
2512 goto out;
2513 debug("client_input_global_request: rtype %s want_reply %d",
2514 rtype, want_reply);
2515 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
2516 success = client_input_hostkeys(ssh);
2517 if (want_reply) {
2518 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS :
2519 SSH2_MSG_REQUEST_FAILURE)) != 0 ||
2520 (r = sshpkt_send(ssh)) != 0 ||
2521 (r = ssh_packet_write_wait(ssh)) != 0)
2522 goto out;
2523 }
2524 r = 0;
2525 out:
2526 free(rtype);
2527 return r;
2528 }
2529
2530 static void
client_send_env(struct ssh * ssh,int id,const char * name,const char * val)2531 client_send_env(struct ssh *ssh, int id, const char *name, const char *val)
2532 {
2533 int r;
2534
2535 debug("channel %d: setting env %s = \"%s\"", id, name, val);
2536 channel_request_start(ssh, id, "env", 0);
2537 if ((r = sshpkt_put_cstring(ssh, name)) != 0 ||
2538 (r = sshpkt_put_cstring(ssh, val)) != 0 ||
2539 (r = sshpkt_send(ssh)) != 0)
2540 fatal_fr(r, "send setenv");
2541 }
2542
2543 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)2544 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
2545 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd,
2546 char **env)
2547 {
2548 size_t i, j, len;
2549 int matched, r;
2550 char *name, *val;
2551 Channel *c = NULL;
2552
2553 debug2_f("id %d", id);
2554
2555 if ((c = channel_lookup(ssh, id)) == NULL)
2556 fatal_f("channel %d: unknown channel", id);
2557
2558 ssh_packet_set_interactive(ssh, want_tty,
2559 options.ip_qos_interactive, options.ip_qos_bulk);
2560
2561 if (want_tty) {
2562 struct winsize ws;
2563
2564 /* Store window size in the packet. */
2565 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1)
2566 memset(&ws, 0, sizeof(ws));
2567
2568 channel_request_start(ssh, id, "pty-req", 1);
2569 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
2570 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : ""))
2571 != 0 ||
2572 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
2573 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
2574 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
2575 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0)
2576 fatal_fr(r, "build pty-req");
2577 if (tiop == NULL)
2578 tiop = get_saved_tio();
2579 ssh_tty_make_modes(ssh, -1, tiop);
2580 if ((r = sshpkt_send(ssh)) != 0)
2581 fatal_fr(r, "send pty-req");
2582 /* XXX wait for reply */
2583 c->client_tty = 1;
2584 }
2585
2586 /* Transfer any environment variables from client to server */
2587 if (options.num_send_env != 0 && env != NULL) {
2588 debug("Sending environment.");
2589 for (i = 0; env[i] != NULL; i++) {
2590 /* Split */
2591 name = xstrdup(env[i]);
2592 if ((val = strchr(name, '=')) == NULL) {
2593 free(name);
2594 continue;
2595 }
2596 *val++ = '\0';
2597
2598 matched = 0;
2599 for (j = 0; j < options.num_send_env; j++) {
2600 if (match_pattern(name, options.send_env[j])) {
2601 matched = 1;
2602 break;
2603 }
2604 }
2605 if (!matched) {
2606 debug3("Ignored env %s", name);
2607 free(name);
2608 continue;
2609 }
2610 client_send_env(ssh, id, name, val);
2611 free(name);
2612 }
2613 }
2614 for (i = 0; i < options.num_setenv; i++) {
2615 /* Split */
2616 name = xstrdup(options.setenv[i]);
2617 if ((val = strchr(name, '=')) == NULL) {
2618 free(name);
2619 continue;
2620 }
2621 *val++ = '\0';
2622 client_send_env(ssh, id, name, val);
2623 free(name);
2624 }
2625
2626 len = sshbuf_len(cmd);
2627 if (len > 0) {
2628 if (len > 900)
2629 len = 900;
2630 if (want_subsystem) {
2631 debug("Sending subsystem: %.*s",
2632 (int)len, (const u_char*)sshbuf_ptr(cmd));
2633 channel_request_start(ssh, id, "subsystem", 1);
2634 client_expect_confirm(ssh, id, "subsystem",
2635 CONFIRM_CLOSE);
2636 } else {
2637 debug("Sending command: %.*s",
2638 (int)len, (const u_char*)sshbuf_ptr(cmd));
2639 channel_request_start(ssh, id, "exec", 1);
2640 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
2641 }
2642 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 ||
2643 (r = sshpkt_send(ssh)) != 0)
2644 fatal_fr(r, "send command");
2645 } else {
2646 channel_request_start(ssh, id, "shell", 1);
2647 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
2648 if ((r = sshpkt_send(ssh)) != 0)
2649 fatal_fr(r, "send shell");
2650 }
2651
2652 session_setup_complete = 1;
2653 client_repledge();
2654 }
2655
2656 static void
client_init_dispatch(struct ssh * ssh)2657 client_init_dispatch(struct ssh *ssh)
2658 {
2659 ssh_dispatch_init(ssh, &dispatch_protocol_error);
2660
2661 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
2662 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
2663 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
2664 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
2665 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
2666 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
2667 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
2668 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
2669 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
2670 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
2671 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
2672 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
2673
2674 /* rekeying */
2675 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
2676
2677 /* global request reply messages */
2678 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
2679 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
2680 }
2681
2682 void
client_stop_mux(void)2683 client_stop_mux(void)
2684 {
2685 if (options.control_path != NULL && muxserver_sock != -1)
2686 unlink(options.control_path);
2687 /*
2688 * If we are in persist mode, or don't have a shell, signal that we
2689 * should close when all active channels are closed.
2690 */
2691 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) {
2692 session_closed = 1;
2693 setproctitle("[stopped mux]");
2694 }
2695 }
2696
2697 /* client specific fatal cleanup */
2698 void
cleanup_exit(int i)2699 cleanup_exit(int i)
2700 {
2701 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2702 if (options.control_path != NULL && muxserver_sock != -1)
2703 unlink(options.control_path);
2704 ssh_kill_proxy_command();
2705 _exit(i);
2706 }
2707