1 /* $OpenBSD: clientloop.c,v 1.410 2024/12/03 22:30:03 jsg 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 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 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 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 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 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 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 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 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 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 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 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 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 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 /* ...unless there's x11 communication happening */ 665 return x11_channel_used_recently(ssh); 666 667 /* Calculate number of intervals missed since the last check */ 668 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000; 669 n += now.tv_nsec - next_interval.tv_nsec; 670 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000; 671 n = (n < 0) ? 1 : n + 1; 672 673 /* Advance to the next interval */ 674 set_next_interval(&now, &next_interval, 675 options.obscure_keystroke_timing_interval * n, 0); 676 return 1; 677 } 678 679 /* 680 * Waits until the client can do something (some data becomes available on 681 * one of the file descriptors). 682 */ 683 static void 684 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp, 685 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue, 686 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp) 687 { 688 struct timespec timeout; 689 int ret, oready; 690 u_int p; 691 692 *conn_in_readyp = *conn_out_readyp = 0; 693 694 /* Prepare channel poll. First two pollfd entries are reserved */ 695 ptimeout_init(&timeout); 696 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 697 if (*npfd_activep < 2) 698 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 699 700 /* channel_prepare_poll could have closed the last channel */ 701 if (session_closed && !channel_still_open(ssh) && 702 !ssh_packet_have_data_to_write(ssh)) { 703 /* clear events since we did not call poll() */ 704 for (p = 0; p < *npfd_activep; p++) 705 (*pfdp)[p].revents = 0; 706 return; 707 } 708 709 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue); 710 711 /* Monitor server connection on reserved pollfd entries */ 712 (*pfdp)[0].fd = connection_in; 713 (*pfdp)[0].events = POLLIN; 714 (*pfdp)[1].fd = connection_out; 715 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ? 716 POLLOUT : 0; 717 718 /* 719 * Wait for something to happen. This will suspend the process until 720 * some polled descriptor can be read, written, or has some other 721 * event pending, or a timeout expires. 722 */ 723 set_control_persist_exit_time(ssh); 724 if (control_persist_exit_time > 0) 725 ptimeout_deadline_monotime(&timeout, control_persist_exit_time); 726 if (options.server_alive_interval > 0) 727 ptimeout_deadline_monotime(&timeout, server_alive_time); 728 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 729 ptimeout_deadline_sec(&timeout, 730 ssh_packet_get_rekey_timeout(ssh)); 731 } 732 733 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp); 734 735 if (ret == -1) { 736 /* 737 * We have to clear the events because we return. 738 * We have to return, because the mainloop checks for the flags 739 * set by the signal handlers. 740 */ 741 for (p = 0; p < *npfd_activep; p++) 742 (*pfdp)[p].revents = 0; 743 if (errno == EINTR) 744 return; 745 /* Note: we might still have data in the buffers. */ 746 quit_message("poll: %s", strerror(errno)); 747 return; 748 } 749 750 *conn_in_readyp = (*pfdp)[0].revents != 0; 751 *conn_out_readyp = (*pfdp)[1].revents != 0; 752 753 if (options.server_alive_interval > 0 && !*conn_in_readyp && 754 monotime() >= server_alive_time) { 755 /* 756 * ServerAlive check is needed. We can't rely on the poll 757 * timing out since traffic on the client side such as port 758 * forwards can keep waking it up. 759 */ 760 server_alive_check(ssh); 761 } 762 } 763 764 static void 765 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr) 766 { 767 /* Flush stdout and stderr buffers. */ 768 if (sshbuf_len(bout) > 0) 769 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout), 770 sshbuf_len(bout)); 771 if (sshbuf_len(berr) > 0) 772 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr), 773 sshbuf_len(berr)); 774 775 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 776 777 sshbuf_reset(bin); 778 sshbuf_reset(bout); 779 sshbuf_reset(berr); 780 781 /* Send the suspend signal to the program itself. */ 782 kill(getpid(), SIGTSTP); 783 784 /* Reset window sizes in case they have changed */ 785 received_window_change_signal = 1; 786 787 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 788 } 789 790 static void 791 client_process_net_input(struct ssh *ssh) 792 { 793 int r; 794 795 /* 796 * Read input from the server, and add any such data to the buffer of 797 * the packet subsystem. 798 */ 799 schedule_server_alive_check(); 800 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 801 return; /* success */ 802 if (r == SSH_ERR_SYSTEM_ERROR) { 803 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK) 804 return; 805 if (errno == EPIPE) { 806 quit_message("Connection to %s closed by remote host.", 807 host); 808 return; 809 } 810 } 811 quit_message("Read from remote host %s: %s", host, ssh_err(r)); 812 } 813 814 static void 815 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) 816 { 817 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; 818 char errmsg[256]; 819 int r, tochan; 820 821 /* 822 * If a TTY was explicitly requested, then a failure to allocate 823 * one is fatal. 824 */ 825 if (cr->action == CONFIRM_TTY && 826 (options.request_tty == REQUEST_TTY_FORCE || 827 options.request_tty == REQUEST_TTY_YES)) 828 cr->action = CONFIRM_CLOSE; 829 830 /* XXX suppress on mux _client_ quietmode */ 831 tochan = options.log_level >= SYSLOG_LEVEL_ERROR && 832 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; 833 834 if (type == SSH2_MSG_CHANNEL_SUCCESS) { 835 debug2("%s request accepted on channel %d", 836 cr->request_type, c->self); 837 } else if (type == SSH2_MSG_CHANNEL_FAILURE) { 838 if (tochan) { 839 snprintf(errmsg, sizeof(errmsg), 840 "%s request failed\r\n", cr->request_type); 841 } else { 842 snprintf(errmsg, sizeof(errmsg), 843 "%s request failed on channel %d", 844 cr->request_type, c->self); 845 } 846 /* If error occurred on primary session channel, then exit */ 847 if (cr->action == CONFIRM_CLOSE && c->self == session_ident) 848 fatal("%s", errmsg); 849 /* 850 * If error occurred on mux client, append to 851 * their stderr. 852 */ 853 if (tochan) { 854 debug3_f("channel %d: mux request: %s", c->self, 855 cr->request_type); 856 if ((r = sshbuf_put(c->extended, errmsg, 857 strlen(errmsg))) != 0) 858 fatal_fr(r, "sshbuf_put"); 859 } else 860 error("%s", errmsg); 861 if (cr->action == CONFIRM_TTY) { 862 /* 863 * If a TTY allocation error occurred, then arrange 864 * for the correct TTY to leave raw mode. 865 */ 866 if (c->self == session_ident) 867 leave_raw_mode(0); 868 else 869 mux_tty_alloc_failed(ssh, c); 870 } else if (cr->action == CONFIRM_CLOSE) { 871 chan_read_failed(ssh, c); 872 chan_write_failed(ssh, c); 873 } 874 } 875 free(cr); 876 } 877 878 static void 879 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) 880 { 881 free(ctx); 882 } 883 884 void 885 client_expect_confirm(struct ssh *ssh, int id, const char *request, 886 enum confirm_action action) 887 { 888 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); 889 890 cr->request_type = request; 891 cr->action = action; 892 893 channel_register_status_confirm(ssh, id, client_status_confirm, 894 client_abandon_status_confirm, cr); 895 } 896 897 void 898 client_register_global_confirm(global_confirm_cb *cb, void *ctx) 899 { 900 struct global_confirm *gc, *last_gc; 901 902 /* Coalesce identical callbacks */ 903 last_gc = TAILQ_LAST(&global_confirms, global_confirms); 904 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { 905 if (++last_gc->ref_count >= INT_MAX) 906 fatal_f("last_gc->ref_count = %d", 907 last_gc->ref_count); 908 return; 909 } 910 911 gc = xcalloc(1, sizeof(*gc)); 912 gc->cb = cb; 913 gc->ctx = ctx; 914 gc->ref_count = 1; 915 TAILQ_INSERT_TAIL(&global_confirms, gc, entry); 916 } 917 918 /* 919 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com 920 * hostkey update request. 921 */ 922 static int 923 can_update_hostkeys(void) 924 { 925 if (hostkeys_update_complete) 926 return 0; 927 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && 928 options.batch_mode) 929 return 0; /* won't ask in batchmode, so don't even try */ 930 if (!options.update_hostkeys || options.num_user_hostfiles <= 0) 931 return 0; 932 return 1; 933 } 934 935 static void 936 client_repledge(void) 937 { 938 debug3_f("enter"); 939 940 /* Might be able to tighten pledge now that session is established */ 941 if (options.control_master || options.control_path != NULL || 942 options.forward_x11 || options.fork_after_authentication || 943 can_update_hostkeys() || 944 (session_ident != -1 && !session_setup_complete)) { 945 /* Can't tighten */ 946 return; 947 } 948 /* 949 * LocalCommand and UpdateHostkeys have finished, so can get rid of 950 * filesystem. 951 * 952 * XXX protocol allows a server can to change hostkeys during the 953 * connection at rekey time that could trigger a hostkeys update 954 * but AFAIK no implementations support this. Could improve by 955 * forcing known_hosts to be read-only or via unveil(2). 956 */ 957 if (options.num_local_forwards != 0 || 958 options.num_remote_forwards != 0 || 959 options.num_permitted_remote_opens != 0 || 960 options.enable_escape_commandline != 0) { 961 /* rfwd needs inet */ 962 debug("pledge: network"); 963 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 964 fatal_f("pledge(): %s", strerror(errno)); 965 } else if (options.forward_agent != 0) { 966 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */ 967 debug("pledge: agent"); 968 if (pledge("stdio unix proc tty", NULL) == -1) 969 fatal_f("pledge(): %s", strerror(errno)); 970 } else { 971 debug("pledge: fork"); 972 if (pledge("stdio proc tty", NULL) == -1) 973 fatal_f("pledge(): %s", strerror(errno)); 974 } 975 /* XXX further things to do: 976 * 977 * - might be able to get rid of proc if we kill ~^Z 978 * - ssh -N (no session) 979 * - stdio forwarding 980 * - sessions without tty 981 */ 982 } 983 984 static void 985 process_cmdline(struct ssh *ssh) 986 { 987 void (*handler)(int); 988 char *s, *cmd; 989 int ok, delete = 0, local = 0, remote = 0, dynamic = 0; 990 struct Forward fwd; 991 992 memset(&fwd, 0, sizeof(fwd)); 993 994 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 995 handler = ssh_signal(SIGINT, SIG_IGN); 996 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); 997 if (s == NULL) 998 goto out; 999 while (isspace((u_char)*s)) 1000 s++; 1001 if (*s == '-') 1002 s++; /* Skip cmdline '-', if any */ 1003 if (*s == '\0') 1004 goto out; 1005 1006 if (*s == 'h' || *s == 'H' || *s == '?') { 1007 logit("Commands:"); 1008 logit(" -L[bind_address:]port:host:hostport " 1009 "Request local forward"); 1010 logit(" -R[bind_address:]port:host:hostport " 1011 "Request remote forward"); 1012 logit(" -D[bind_address:]port " 1013 "Request dynamic forward"); 1014 logit(" -KL[bind_address:]port " 1015 "Cancel local forward"); 1016 logit(" -KR[bind_address:]port " 1017 "Cancel remote forward"); 1018 logit(" -KD[bind_address:]port " 1019 "Cancel dynamic forward"); 1020 if (!options.permit_local_command) 1021 goto out; 1022 logit(" !args " 1023 "Execute local command"); 1024 goto out; 1025 } 1026 1027 if (*s == '!' && options.permit_local_command) { 1028 s++; 1029 ssh_local_cmd(s); 1030 goto out; 1031 } 1032 1033 if (*s == 'K') { 1034 delete = 1; 1035 s++; 1036 } 1037 if (*s == 'L') 1038 local = 1; 1039 else if (*s == 'R') 1040 remote = 1; 1041 else if (*s == 'D') 1042 dynamic = 1; 1043 else { 1044 logit("Invalid command."); 1045 goto out; 1046 } 1047 1048 while (isspace((u_char)*++s)) 1049 ; 1050 1051 /* XXX update list of forwards in options */ 1052 if (delete) { 1053 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ 1054 if (!parse_forward(&fwd, s, 1, 0)) { 1055 logit("Bad forwarding close specification."); 1056 goto out; 1057 } 1058 if (remote) 1059 ok = channel_request_rforward_cancel(ssh, &fwd) == 0; 1060 else if (dynamic) 1061 ok = channel_cancel_lport_listener(ssh, &fwd, 1062 0, &options.fwd_opts) > 0; 1063 else 1064 ok = channel_cancel_lport_listener(ssh, &fwd, 1065 CHANNEL_CANCEL_PORT_STATIC, 1066 &options.fwd_opts) > 0; 1067 if (!ok) { 1068 logit("Unknown port forwarding."); 1069 goto out; 1070 } 1071 logit("Canceled forwarding."); 1072 } else { 1073 /* -R specs can be both dynamic or not, so check both. */ 1074 if (remote) { 1075 if (!parse_forward(&fwd, s, 0, remote) && 1076 !parse_forward(&fwd, s, 1, remote)) { 1077 logit("Bad remote forwarding specification."); 1078 goto out; 1079 } 1080 } else if (!parse_forward(&fwd, s, dynamic, remote)) { 1081 logit("Bad local forwarding specification."); 1082 goto out; 1083 } 1084 if (local || dynamic) { 1085 if (!channel_setup_local_fwd_listener(ssh, &fwd, 1086 &options.fwd_opts)) { 1087 logit("Port forwarding failed."); 1088 goto out; 1089 } 1090 } else { 1091 if (channel_request_remote_forwarding(ssh, &fwd) < 0) { 1092 logit("Port forwarding failed."); 1093 goto out; 1094 } 1095 } 1096 logit("Forwarding port."); 1097 } 1098 1099 out: 1100 ssh_signal(SIGINT, handler); 1101 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1102 free(cmd); 1103 free(fwd.listen_host); 1104 free(fwd.listen_path); 1105 free(fwd.connect_host); 1106 free(fwd.connect_path); 1107 } 1108 1109 /* reasons to suppress output of an escape command in help output */ 1110 #define SUPPRESS_NEVER 0 /* never suppress, always show */ 1111 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ 1112 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ 1113 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ 1114 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/ 1115 struct escape_help_text { 1116 const char *cmd; 1117 const char *text; 1118 unsigned int flags; 1119 }; 1120 static struct escape_help_text esc_txt[] = { 1121 {".", "terminate session", SUPPRESS_MUXMASTER}, 1122 {".", "terminate connection (and any multiplexed sessions)", 1123 SUPPRESS_MUXCLIENT}, 1124 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, 1125 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE}, 1126 {"R", "request rekey", SUPPRESS_NEVER}, 1127 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, 1128 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, 1129 {"#", "list forwarded connections", SUPPRESS_NEVER}, 1130 {"&", "background ssh (when waiting for connections to terminate)", 1131 SUPPRESS_MUXCLIENT}, 1132 {"?", "this message", SUPPRESS_NEVER}, 1133 }; 1134 1135 static void 1136 print_escape_help(struct sshbuf *b, int escape_char, int mux_client, 1137 int using_stderr) 1138 { 1139 unsigned int i, suppress_flags; 1140 int r; 1141 1142 if ((r = sshbuf_putf(b, 1143 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0) 1144 fatal_fr(r, "sshbuf_putf"); 1145 1146 suppress_flags = 1147 (mux_client ? SUPPRESS_MUXCLIENT : 0) | 1148 (mux_client ? 0 : SUPPRESS_MUXMASTER) | 1149 (using_stderr ? 0 : SUPPRESS_SYSLOG) | 1150 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0); 1151 1152 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { 1153 if (esc_txt[i].flags & suppress_flags) 1154 continue; 1155 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n", 1156 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0) 1157 fatal_fr(r, "sshbuf_putf"); 1158 } 1159 1160 if ((r = sshbuf_putf(b, 1161 " %c%c - send the escape character by typing it twice\r\n" 1162 "(Note that escapes are only recognized immediately after " 1163 "newline.)\r\n", escape_char, escape_char)) != 0) 1164 fatal_fr(r, "sshbuf_putf"); 1165 } 1166 1167 /* 1168 * Process the characters one by one. 1169 */ 1170 static int 1171 process_escapes(struct ssh *ssh, Channel *c, 1172 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr, 1173 char *buf, int len) 1174 { 1175 pid_t pid; 1176 int r, bytes = 0; 1177 u_int i; 1178 u_char ch; 1179 char *s; 1180 struct escape_filter_ctx *efc; 1181 1182 if (c == NULL || c->filter_ctx == NULL || len <= 0) 1183 return 0; 1184 1185 efc = (struct escape_filter_ctx *)c->filter_ctx; 1186 1187 for (i = 0; i < (u_int)len; i++) { 1188 /* Get one character at a time. */ 1189 ch = buf[i]; 1190 1191 if (efc->escape_pending) { 1192 /* We have previously seen an escape character. */ 1193 /* Clear the flag now. */ 1194 efc->escape_pending = 0; 1195 1196 /* Process the escaped character. */ 1197 switch (ch) { 1198 case '.': 1199 /* Terminate the connection. */ 1200 if ((r = sshbuf_putf(berr, "%c.\r\n", 1201 efc->escape_char)) != 0) 1202 fatal_fr(r, "sshbuf_putf"); 1203 if (c && c->ctl_chan != -1) { 1204 channel_force_close(ssh, c, 1); 1205 return 0; 1206 } else 1207 quit_pending = 1; 1208 return -1; 1209 1210 case 'Z' - 64: 1211 /* XXX support this for mux clients */ 1212 if (c && c->ctl_chan != -1) { 1213 char b[16]; 1214 noescape: 1215 if (ch == 'Z' - 64) 1216 snprintf(b, sizeof b, "^Z"); 1217 else 1218 snprintf(b, sizeof b, "%c", ch); 1219 if ((r = sshbuf_putf(berr, 1220 "%c%s escape not available to " 1221 "multiplexed sessions\r\n", 1222 efc->escape_char, b)) != 0) 1223 fatal_fr(r, "sshbuf_putf"); 1224 continue; 1225 } 1226 /* Suspend the program. Inform the user */ 1227 if ((r = sshbuf_putf(berr, 1228 "%c^Z [suspend ssh]\r\n", 1229 efc->escape_char)) != 0) 1230 fatal_fr(r, "sshbuf_putf"); 1231 1232 /* Restore terminal modes and suspend. */ 1233 client_suspend_self(bin, bout, berr); 1234 1235 /* We have been continued. */ 1236 continue; 1237 1238 case 'B': 1239 if ((r = sshbuf_putf(berr, 1240 "%cB\r\n", efc->escape_char)) != 0) 1241 fatal_fr(r, "sshbuf_putf"); 1242 channel_request_start(ssh, c->self, "break", 0); 1243 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 || 1244 (r = sshpkt_send(ssh)) != 0) 1245 fatal_fr(r, "send packet"); 1246 continue; 1247 1248 case 'R': 1249 if (ssh->compat & SSH_BUG_NOREKEY) 1250 logit("Server does not " 1251 "support re-keying"); 1252 else 1253 need_rekeying = 1; 1254 continue; 1255 1256 case 'V': 1257 /* FALLTHROUGH */ 1258 case 'v': 1259 if (c && c->ctl_chan != -1) 1260 goto noescape; 1261 if (!log_is_on_stderr()) { 1262 if ((r = sshbuf_putf(berr, 1263 "%c%c [Logging to syslog]\r\n", 1264 efc->escape_char, ch)) != 0) 1265 fatal_fr(r, "sshbuf_putf"); 1266 continue; 1267 } 1268 if (ch == 'V' && options.log_level > 1269 SYSLOG_LEVEL_QUIET) 1270 log_change_level(--options.log_level); 1271 if (ch == 'v' && options.log_level < 1272 SYSLOG_LEVEL_DEBUG3) 1273 log_change_level(++options.log_level); 1274 if ((r = sshbuf_putf(berr, 1275 "%c%c [LogLevel %s]\r\n", 1276 efc->escape_char, ch, 1277 log_level_name(options.log_level))) != 0) 1278 fatal_fr(r, "sshbuf_putf"); 1279 continue; 1280 1281 case '&': 1282 if (c->ctl_chan != -1) 1283 goto noescape; 1284 /* 1285 * Detach the program (continue to serve 1286 * connections, but put in background and no 1287 * more new connections). 1288 */ 1289 /* Restore tty modes. */ 1290 leave_raw_mode( 1291 options.request_tty == REQUEST_TTY_FORCE); 1292 1293 /* Stop listening for new connections. */ 1294 channel_stop_listening(ssh); 1295 1296 if ((r = sshbuf_putf(berr, "%c& " 1297 "[backgrounded]\n", efc->escape_char)) != 0) 1298 fatal_fr(r, "sshbuf_putf"); 1299 1300 /* Fork into background. */ 1301 pid = fork(); 1302 if (pid == -1) { 1303 error("fork: %.100s", strerror(errno)); 1304 continue; 1305 } 1306 if (pid != 0) { /* This is the parent. */ 1307 /* The parent just exits. */ 1308 exit(0); 1309 } 1310 /* The child continues serving connections. */ 1311 /* fake EOF on stdin */ 1312 if ((r = sshbuf_put_u8(bin, 4)) != 0) 1313 fatal_fr(r, "sshbuf_put_u8"); 1314 return -1; 1315 case '?': 1316 print_escape_help(berr, efc->escape_char, 1317 (c && c->ctl_chan != -1), 1318 log_is_on_stderr()); 1319 continue; 1320 1321 case '#': 1322 if ((r = sshbuf_putf(berr, "%c#\r\n", 1323 efc->escape_char)) != 0) 1324 fatal_fr(r, "sshbuf_putf"); 1325 s = channel_open_message(ssh); 1326 if ((r = sshbuf_put(berr, s, strlen(s))) != 0) 1327 fatal_fr(r, "sshbuf_put"); 1328 free(s); 1329 continue; 1330 1331 case 'C': 1332 if (c && c->ctl_chan != -1) 1333 goto noescape; 1334 if (options.enable_escape_commandline == 0) { 1335 if ((r = sshbuf_putf(berr, 1336 "commandline disabled\r\n")) != 0) 1337 fatal_fr(r, "sshbuf_putf"); 1338 continue; 1339 } 1340 process_cmdline(ssh); 1341 continue; 1342 1343 default: 1344 if (ch != efc->escape_char) { 1345 if ((r = sshbuf_put_u8(bin, 1346 efc->escape_char)) != 0) 1347 fatal_fr(r, "sshbuf_put_u8"); 1348 bytes++; 1349 } 1350 /* Escaped characters fall through here */ 1351 break; 1352 } 1353 } else { 1354 /* 1355 * The previous character was not an escape char. 1356 * Check if this is an escape. 1357 */ 1358 if (last_was_cr && ch == efc->escape_char) { 1359 /* 1360 * It is. Set the flag and continue to 1361 * next character. 1362 */ 1363 efc->escape_pending = 1; 1364 continue; 1365 } 1366 } 1367 1368 /* 1369 * Normal character. Record whether it was a newline, 1370 * and append it to the buffer. 1371 */ 1372 last_was_cr = (ch == '\r' || ch == '\n'); 1373 if ((r = sshbuf_put_u8(bin, ch)) != 0) 1374 fatal_fr(r, "sshbuf_put_u8"); 1375 bytes++; 1376 } 1377 return bytes; 1378 } 1379 1380 /* 1381 * Get packets from the connection input buffer, and process them as long as 1382 * there are packets available. 1383 * 1384 * Any unknown packets received during the actual 1385 * session cause the session to terminate. This is 1386 * intended to make debugging easier since no 1387 * confirmations are sent. Any compatible protocol 1388 * extensions must be negotiated during the 1389 * preparatory phase. 1390 */ 1391 1392 static void 1393 client_process_buffered_input_packets(struct ssh *ssh) 1394 { 1395 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending); 1396 } 1397 1398 /* scan buf[] for '~' before sending data to the peer */ 1399 1400 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ 1401 void * 1402 client_new_escape_filter_ctx(int escape_char) 1403 { 1404 struct escape_filter_ctx *ret; 1405 1406 ret = xcalloc(1, sizeof(*ret)); 1407 ret->escape_pending = 0; 1408 ret->escape_char = escape_char; 1409 return (void *)ret; 1410 } 1411 1412 /* Free the escape filter context on channel free */ 1413 void 1414 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) 1415 { 1416 free(ctx); 1417 } 1418 1419 int 1420 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len) 1421 { 1422 if (c->extended_usage != CHAN_EXTENDED_WRITE) 1423 return 0; 1424 1425 return process_escapes(ssh, c, c->input, c->output, c->extended, 1426 buf, len); 1427 } 1428 1429 static void 1430 client_channel_closed(struct ssh *ssh, int id, int force, void *arg) 1431 { 1432 channel_cancel_cleanup(ssh, id); 1433 session_closed = 1; 1434 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1435 } 1436 1437 /* 1438 * Implements the interactive session with the server. This is called after 1439 * the user has been authenticated, and a command has been started on the 1440 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character 1441 * used as an escape character for terminating or suspending the session. 1442 */ 1443 int 1444 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, 1445 int ssh2_chan_id) 1446 { 1447 struct pollfd *pfd = NULL; 1448 u_int npfd_alloc = 0, npfd_active = 0; 1449 double start_time, total_time; 1450 int channel_did_enqueue = 0, r; 1451 u_int64_t ibytes, obytes; 1452 int conn_in_ready, conn_out_ready; 1453 sigset_t bsigset, osigset; 1454 1455 debug("Entering interactive session."); 1456 session_ident = ssh2_chan_id; 1457 1458 if (options.control_master && 1459 !option_clear_or_none(options.control_path)) { 1460 debug("pledge: id"); 1461 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty", 1462 NULL) == -1) 1463 fatal_f("pledge(): %s", strerror(errno)); 1464 1465 } else if (options.forward_x11 || options.permit_local_command) { 1466 debug("pledge: exec"); 1467 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty", 1468 NULL) == -1) 1469 fatal_f("pledge(): %s", strerror(errno)); 1470 1471 } else if (options.update_hostkeys) { 1472 debug("pledge: filesystem"); 1473 if (pledge("stdio rpath wpath cpath unix inet dns proc tty", 1474 NULL) == -1) 1475 fatal_f("pledge(): %s", strerror(errno)); 1476 1477 } else if (!option_clear_or_none(options.proxy_command) || 1478 options.fork_after_authentication) { 1479 debug("pledge: proc"); 1480 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1) 1481 fatal_f("pledge(): %s", strerror(errno)); 1482 1483 } else { 1484 debug("pledge: network"); 1485 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 1486 fatal_f("pledge(): %s", strerror(errno)); 1487 } 1488 1489 /* might be able to tighten now */ 1490 client_repledge(); 1491 1492 start_time = monotime_double(); 1493 1494 /* Initialize variables. */ 1495 last_was_cr = 1; 1496 exit_status = -1; 1497 connection_in = ssh_packet_get_connection_in(ssh); 1498 connection_out = ssh_packet_get_connection_out(ssh); 1499 1500 quit_pending = 0; 1501 1502 client_init_dispatch(ssh); 1503 1504 /* 1505 * Set signal handlers, (e.g. to restore non-blocking mode) 1506 * but don't overwrite SIG_IGN, matches behaviour from rsh(1) 1507 */ 1508 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN) 1509 ssh_signal(SIGHUP, signal_handler); 1510 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN) 1511 ssh_signal(SIGINT, signal_handler); 1512 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN) 1513 ssh_signal(SIGQUIT, signal_handler); 1514 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN) 1515 ssh_signal(SIGTERM, signal_handler); 1516 ssh_signal(SIGWINCH, window_change_handler); 1517 1518 if (have_pty) 1519 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1520 1521 if (session_ident != -1) { 1522 if (escape_char_arg != SSH_ESCAPECHAR_NONE) { 1523 channel_register_filter(ssh, session_ident, 1524 client_simple_escape_filter, NULL, 1525 client_filter_cleanup, 1526 client_new_escape_filter_ctx( 1527 escape_char_arg)); 1528 } 1529 channel_register_cleanup(ssh, session_ident, 1530 client_channel_closed, 0); 1531 } 1532 1533 schedule_server_alive_check(); 1534 1535 if (sigemptyset(&bsigset) == -1 || 1536 sigaddset(&bsigset, SIGHUP) == -1 || 1537 sigaddset(&bsigset, SIGINT) == -1 || 1538 sigaddset(&bsigset, SIGQUIT) == -1 || 1539 sigaddset(&bsigset, SIGTERM) == -1) 1540 error_f("bsigset setup: %s", strerror(errno)); 1541 1542 /* Main loop of the client for the interactive session mode. */ 1543 while (!quit_pending) { 1544 channel_did_enqueue = 0; 1545 1546 /* Process buffered packets sent by the server. */ 1547 client_process_buffered_input_packets(ssh); 1548 1549 if (session_closed && !channel_still_open(ssh)) 1550 break; 1551 1552 if (ssh_packet_is_rekeying(ssh)) { 1553 debug("rekeying in progress"); 1554 } else if (need_rekeying) { 1555 /* manual rekey request */ 1556 debug("need rekeying"); 1557 if ((r = kex_start_rekex(ssh)) != 0) 1558 fatal_fr(r, "kex_start_rekex"); 1559 need_rekeying = 0; 1560 } else { 1561 /* 1562 * Make packets from buffered channel data, and 1563 * enqueue them for sending to the server. 1564 */ 1565 if (ssh_packet_not_very_much_data_to_write(ssh)) 1566 channel_did_enqueue = channel_output_poll(ssh); 1567 1568 /* 1569 * Check if the window size has changed, and buffer a 1570 * message about it to the server if so. 1571 */ 1572 client_check_window_change(ssh); 1573 } 1574 /* 1575 * Wait until we have something to do (something becomes 1576 * available on one of the descriptors). 1577 */ 1578 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1) 1579 error_f("bsigset sigprocmask: %s", strerror(errno)); 1580 if (quit_pending) 1581 break; 1582 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc, 1583 &npfd_active, channel_did_enqueue, &osigset, 1584 &conn_in_ready, &conn_out_ready); 1585 if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1) 1586 error_f("osigset sigprocmask: %s", strerror(errno)); 1587 1588 if (quit_pending) 1589 break; 1590 1591 /* Do channel operations. */ 1592 channel_after_poll(ssh, pfd, npfd_active); 1593 1594 /* Buffer input from the connection. */ 1595 if (conn_in_ready) 1596 client_process_net_input(ssh); 1597 1598 if (quit_pending) 1599 break; 1600 1601 /* A timeout may have triggered rekeying */ 1602 if ((r = ssh_packet_check_rekey(ssh)) != 0) 1603 fatal_fr(r, "cannot start rekeying"); 1604 1605 /* 1606 * Send as much buffered packet data as possible to the 1607 * sender. 1608 */ 1609 if (conn_out_ready) { 1610 if ((r = ssh_packet_write_poll(ssh)) != 0) { 1611 sshpkt_fatal(ssh, r, 1612 "%s: ssh_packet_write_poll", __func__); 1613 } 1614 } 1615 1616 /* 1617 * If we are a backgrounded control master, and the 1618 * timeout has expired without any active client 1619 * connections, then quit. 1620 */ 1621 if (control_persist_exit_time > 0) { 1622 if (monotime() >= control_persist_exit_time) { 1623 debug("ControlPersist timeout expired"); 1624 break; 1625 } 1626 } 1627 } 1628 free(pfd); 1629 1630 /* Terminate the session. */ 1631 1632 /* 1633 * In interactive mode (with pseudo tty) display a message indicating 1634 * that the connection has been closed. 1635 */ 1636 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO) 1637 quit_message("Connection to %s closed.", host); 1638 1639 1640 /* Stop watching for window change. */ 1641 ssh_signal(SIGWINCH, SIG_DFL); 1642 1643 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || 1644 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 || 1645 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 || 1646 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */ 1647 (r = sshpkt_send(ssh)) != 0 || 1648 (r = ssh_packet_write_wait(ssh)) != 0) 1649 fatal_fr(r, "send disconnect"); 1650 1651 channel_free_all(ssh); 1652 1653 if (have_pty) 1654 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1655 1656 /* 1657 * If there was no shell or command requested, there will be no remote 1658 * exit status to be returned. In that case, clear error code if the 1659 * connection was deliberately terminated at this end. 1660 */ 1661 if (options.session_type == SESSION_TYPE_NONE && 1662 received_signal == SIGTERM) { 1663 received_signal = 0; 1664 exit_status = 0; 1665 } 1666 1667 if (received_signal) { 1668 verbose("Killed by signal %d.", (int) received_signal); 1669 cleanup_exit(255); 1670 } 1671 1672 /* Report bytes transferred, and transfer rates. */ 1673 total_time = monotime_double() - start_time; 1674 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1675 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", 1676 (unsigned long long)obytes, (unsigned long long)ibytes, total_time); 1677 if (total_time > 0) 1678 verbose("Bytes per second: sent %.1f, received %.1f", 1679 obytes / total_time, ibytes / total_time); 1680 /* Return the exit status of the program. */ 1681 debug("Exit status %d", exit_status); 1682 return exit_status; 1683 } 1684 1685 /*********/ 1686 1687 static Channel * 1688 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, 1689 int rchan, u_int rwindow, u_int rmaxpack) 1690 { 1691 Channel *c = NULL; 1692 struct sshbuf *b = NULL; 1693 char *listen_address, *originator_address; 1694 u_int listen_port, originator_port; 1695 int r; 1696 1697 /* Get rest of the packet */ 1698 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 || 1699 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 || 1700 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 || 1701 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1702 (r = sshpkt_get_end(ssh)) != 0) 1703 fatal_fr(r, "parse packet"); 1704 1705 debug_f("listen %s port %d, originator %s port %d", 1706 listen_address, listen_port, originator_address, originator_port); 1707 1708 if (listen_port > 0xffff) 1709 error_f("invalid listen port"); 1710 else if (originator_port > 0xffff) 1711 error_f("invalid originator port"); 1712 else { 1713 c = channel_connect_by_listen_address(ssh, 1714 listen_address, listen_port, "forwarded-tcpip", 1715 originator_address); 1716 } 1717 1718 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1719 if ((b = sshbuf_new()) == NULL) { 1720 error_f("alloc reply"); 1721 goto out; 1722 } 1723 /* reconstruct and send to muxclient */ 1724 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ 1725 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1726 (r = sshbuf_put_cstring(b, request_type)) != 0 || 1727 (r = sshbuf_put_u32(b, rchan)) != 0 || 1728 (r = sshbuf_put_u32(b, rwindow)) != 0 || 1729 (r = sshbuf_put_u32(b, rmaxpack)) != 0 || 1730 (r = sshbuf_put_cstring(b, listen_address)) != 0 || 1731 (r = sshbuf_put_u32(b, listen_port)) != 0 || 1732 (r = sshbuf_put_cstring(b, originator_address)) != 0 || 1733 (r = sshbuf_put_u32(b, originator_port)) != 0 || 1734 (r = sshbuf_put_stringb(c->output, b)) != 0) { 1735 error_fr(r, "compose for muxclient"); 1736 goto out; 1737 } 1738 } 1739 1740 out: 1741 sshbuf_free(b); 1742 free(originator_address); 1743 free(listen_address); 1744 return c; 1745 } 1746 1747 static Channel * 1748 client_request_forwarded_streamlocal(struct ssh *ssh, 1749 const char *request_type, int rchan) 1750 { 1751 Channel *c = NULL; 1752 char *listen_path; 1753 int r; 1754 1755 /* Get the remote path. */ 1756 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 || 1757 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */ 1758 (r = sshpkt_get_end(ssh)) != 0) 1759 fatal_fr(r, "parse packet"); 1760 1761 debug_f("request: %s", listen_path); 1762 1763 c = channel_connect_by_listen_path(ssh, listen_path, 1764 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); 1765 free(listen_path); 1766 return c; 1767 } 1768 1769 static Channel * 1770 client_request_x11(struct ssh *ssh, const char *request_type, int rchan) 1771 { 1772 Channel *c = NULL; 1773 char *originator; 1774 u_int originator_port; 1775 int r, sock; 1776 1777 if (!options.forward_x11) { 1778 error("Warning: ssh server tried X11 forwarding."); 1779 error("Warning: this is probably a break-in attempt by a " 1780 "malicious server."); 1781 return NULL; 1782 } 1783 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) { 1784 verbose("Rejected X11 connection after ForwardX11Timeout " 1785 "expired"); 1786 return NULL; 1787 } 1788 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 1789 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1790 (r = sshpkt_get_end(ssh)) != 0) 1791 fatal_fr(r, "parse packet"); 1792 /* XXX check permission */ 1793 /* XXX range check originator port? */ 1794 debug("client_request_x11: request from %s %u", originator, 1795 originator_port); 1796 free(originator); 1797 sock = x11_connect_display(ssh); 1798 if (sock < 0) 1799 return NULL; 1800 c = channel_new(ssh, "x11-connection", 1801 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1802 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1803 c->force_drain = 1; 1804 return c; 1805 } 1806 1807 static Channel * 1808 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1809 { 1810 Channel *c = NULL; 1811 int r, sock; 1812 1813 if (!options.forward_agent) { 1814 error("Warning: ssh server tried agent forwarding."); 1815 error("Warning: this is probably a break-in attempt by a " 1816 "malicious server."); 1817 return NULL; 1818 } 1819 if (forward_agent_sock_path == NULL) { 1820 r = ssh_get_authentication_socket(&sock); 1821 } else { 1822 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1823 } 1824 if (r != 0) { 1825 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1826 debug_fr(r, "ssh_get_authentication_socket"); 1827 return NULL; 1828 } 1829 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1830 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1831 debug_f("bound agent to hostkey"); 1832 else 1833 debug2_fr(r, "ssh_agent_bind_hostkey"); 1834 1835 c = channel_new(ssh, "agent-connection", 1836 SSH_CHANNEL_OPEN, sock, sock, -1, 1837 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1838 "authentication agent connection", 1); 1839 c->force_drain = 1; 1840 return c; 1841 } 1842 1843 char * 1844 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1845 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1846 { 1847 Channel *c; 1848 int r, fd; 1849 char *ifname = NULL; 1850 1851 if (tun_mode == SSH_TUNMODE_NO) 1852 return 0; 1853 1854 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1855 1856 /* Open local tunnel device */ 1857 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1858 error("Tunnel device open failed."); 1859 return NULL; 1860 } 1861 debug("Tunnel forwarding using interface %s", ifname); 1862 1863 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1864 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1865 c->datagram = 1; 1866 1867 #if defined(SSH_TUN_FILTER) 1868 if (options.tun_open == SSH_TUNMODE_POINTOPOINT) 1869 channel_register_filter(ssh, c->self, sys_tun_infilter, 1870 sys_tun_outfilter, NULL, NULL); 1871 #endif 1872 1873 if (cb != NULL) 1874 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1875 1876 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1877 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1878 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1879 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1880 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1881 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1882 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1883 (r = sshpkt_send(ssh)) != 0) 1884 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1885 1886 return ifname; 1887 } 1888 1889 /* XXXX move to generic input handler */ 1890 static int 1891 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1892 { 1893 Channel *c = NULL; 1894 char *ctype = NULL; 1895 int r; 1896 u_int rchan; 1897 size_t len; 1898 u_int rmaxpack, rwindow; 1899 1900 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1901 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1902 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1903 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1904 goto out; 1905 1906 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1907 ctype, rchan, rwindow, rmaxpack); 1908 1909 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1910 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1911 rmaxpack); 1912 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1913 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1914 } else if (strcmp(ctype, "x11") == 0) { 1915 c = client_request_x11(ssh, ctype, rchan); 1916 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1917 c = client_request_agent(ssh, ctype, rchan); 1918 } 1919 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1920 debug3("proxied to downstream: %s", ctype); 1921 } else if (c != NULL) { 1922 debug("confirm %s", ctype); 1923 c->remote_id = rchan; 1924 c->have_remote_id = 1; 1925 c->remote_window = rwindow; 1926 c->remote_maxpacket = rmaxpack; 1927 if (c->type != SSH_CHANNEL_CONNECTING) { 1928 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1929 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1930 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1931 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1932 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1933 (r = sshpkt_send(ssh)) != 0) 1934 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1935 } 1936 } else { 1937 debug("failure %s", ctype); 1938 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1939 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1940 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1941 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1942 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1943 (r = sshpkt_send(ssh)) != 0) 1944 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1945 } 1946 r = 0; 1947 out: 1948 free(ctype); 1949 return r; 1950 } 1951 1952 static int 1953 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1954 { 1955 Channel *c = NULL; 1956 char *rtype = NULL; 1957 u_char reply; 1958 u_int id, exitval; 1959 int r, success = 0; 1960 1961 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1962 return r; 1963 if (id <= INT_MAX) 1964 c = channel_lookup(ssh, id); 1965 if (channel_proxy_upstream(c, type, seq, ssh)) 1966 return 0; 1967 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1968 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1969 goto out; 1970 1971 debug("client_input_channel_req: channel %u rtype %s reply %d", 1972 id, rtype, reply); 1973 1974 if (c == NULL) { 1975 error("client_input_channel_req: channel %d: " 1976 "unknown channel", id); 1977 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 1978 if ((r = sshpkt_get_end(ssh)) != 0) 1979 goto out; 1980 chan_rcvd_eow(ssh, c); 1981 } else if (strcmp(rtype, "exit-status") == 0) { 1982 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 1983 goto out; 1984 if (c->ctl_chan != -1) { 1985 mux_exit_message(ssh, c, exitval); 1986 success = 1; 1987 } else if ((int)id == session_ident) { 1988 /* Record exit value of local session */ 1989 success = 1; 1990 exit_status = exitval; 1991 } else { 1992 /* Probably for a mux channel that has already closed */ 1993 debug_f("no sink for exit-status on channel %d", 1994 id); 1995 } 1996 if ((r = sshpkt_get_end(ssh)) != 0) 1997 goto out; 1998 } 1999 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 2000 if (!c->have_remote_id) 2001 fatal_f("channel %d: no remote_id", c->self); 2002 if ((r = sshpkt_start(ssh, success ? 2003 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2004 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2005 (r = sshpkt_send(ssh)) != 0) 2006 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2007 } 2008 r = 0; 2009 out: 2010 free(rtype); 2011 return r; 2012 } 2013 2014 struct hostkeys_update_ctx { 2015 /* The hostname and (optionally) IP address string for the server */ 2016 char *host_str, *ip_str; 2017 2018 /* 2019 * Keys received from the server and a flag for each indicating 2020 * whether they already exist in known_hosts. 2021 * keys_match is filled in by hostkeys_find() and later (for new 2022 * keys) by client_global_hostkeys_prove_confirm(). 2023 */ 2024 struct sshkey **keys; 2025 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2026 int *keys_verified; /* flag for new keys verified by server */ 2027 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2028 2029 /* 2030 * Keys that are in known_hosts, but were not present in the update 2031 * from the server (i.e. scheduled to be deleted). 2032 * Filled in by hostkeys_find(). 2033 */ 2034 struct sshkey **old_keys; 2035 size_t nold; 2036 2037 /* Various special cases. */ 2038 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2039 int ca_available; /* saw CA key for this host */ 2040 int old_key_seen; /* saw old key with other name/addr */ 2041 int other_name_seen; /* saw key with other name/addr */ 2042 }; 2043 2044 static void 2045 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2046 { 2047 size_t i; 2048 2049 if (ctx == NULL) 2050 return; 2051 for (i = 0; i < ctx->nkeys; i++) 2052 sshkey_free(ctx->keys[i]); 2053 free(ctx->keys); 2054 free(ctx->keys_match); 2055 free(ctx->keys_verified); 2056 for (i = 0; i < ctx->nold; i++) 2057 sshkey_free(ctx->old_keys[i]); 2058 free(ctx->old_keys); 2059 free(ctx->host_str); 2060 free(ctx->ip_str); 2061 free(ctx); 2062 } 2063 2064 /* 2065 * Returns non-zero if a known_hosts hostname list is not of a form that 2066 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2067 * hostnames lists that do not follow the form host[,ip]. 2068 */ 2069 static int 2070 hostspec_is_complex(const char *hosts) 2071 { 2072 char *cp; 2073 2074 /* wildcard */ 2075 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2076 return 1; 2077 /* single host/ip = ok */ 2078 if ((cp = strchr(hosts, ',')) == NULL) 2079 return 0; 2080 /* more than two entries on the line */ 2081 if (strchr(cp + 1, ',') != NULL) 2082 return 1; 2083 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2084 return 0; 2085 } 2086 2087 /* callback to search for ctx->keys in known_hosts */ 2088 static int 2089 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2090 { 2091 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2092 size_t i; 2093 struct sshkey **tmp; 2094 2095 if (l->key == NULL) 2096 return 0; 2097 if (l->status != HKF_STATUS_MATCHED) { 2098 /* Record if one of the keys appears on a non-matching line */ 2099 for (i = 0; i < ctx->nkeys; i++) { 2100 if (sshkey_equal(l->key, ctx->keys[i])) { 2101 ctx->other_name_seen = 1; 2102 debug3_f("found %s key under different " 2103 "name/addr at %s:%ld", 2104 sshkey_ssh_name(ctx->keys[i]), 2105 l->path, l->linenum); 2106 return 0; 2107 } 2108 } 2109 return 0; 2110 } 2111 /* Don't proceed if revocation or CA markers are present */ 2112 /* XXX relax this */ 2113 if (l->marker != MRK_NONE) { 2114 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2115 l->path, l->linenum); 2116 ctx->complex_hostspec = 1; 2117 return 0; 2118 } 2119 2120 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2121 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2122 if ((l->match & HKF_MATCH_HOST) == 0) { 2123 /* Record if address matched a different hostname. */ 2124 ctx->other_name_seen = 1; 2125 debug3_f("found address %s against different hostname " 2126 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2127 return 0; 2128 } else if ((l->match & HKF_MATCH_IP) == 0) { 2129 /* Record if hostname matched a different address. */ 2130 ctx->other_name_seen = 1; 2131 debug3_f("found hostname %s against different address " 2132 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2133 } 2134 } 2135 2136 /* 2137 * UpdateHostkeys is skipped for wildcard host names and hostnames 2138 * that contain more than two entries (ssh never writes these). 2139 */ 2140 if (hostspec_is_complex(l->hosts)) { 2141 debug3_f("hostkeys file %s:%ld complex host specification", 2142 l->path, l->linenum); 2143 ctx->complex_hostspec = 1; 2144 return 0; 2145 } 2146 2147 /* Mark off keys we've already seen for this host */ 2148 for (i = 0; i < ctx->nkeys; i++) { 2149 if (!sshkey_equal(l->key, ctx->keys[i])) 2150 continue; 2151 debug3_f("found %s key at %s:%ld", 2152 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2153 ctx->keys_match[i] |= l->match; 2154 return 0; 2155 } 2156 /* This line contained a key that not offered by the server */ 2157 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2158 l->path, l->linenum); 2159 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2160 sizeof(*ctx->old_keys))) == NULL) 2161 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2162 ctx->old_keys = tmp; 2163 ctx->old_keys[ctx->nold++] = l->key; 2164 l->key = NULL; 2165 2166 return 0; 2167 } 2168 2169 /* callback to search for ctx->old_keys in known_hosts under other names */ 2170 static int 2171 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2172 { 2173 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2174 size_t i; 2175 int hashed; 2176 2177 /* only care about lines that *don't* match the active host spec */ 2178 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2179 return 0; 2180 2181 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2182 for (i = 0; i < ctx->nold; i++) { 2183 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2184 continue; 2185 debug3_f("found deprecated %s key at %s:%ld as %s", 2186 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2187 hashed ? "[HASHED]" : l->hosts); 2188 ctx->old_key_seen = 1; 2189 break; 2190 } 2191 return 0; 2192 } 2193 2194 /* 2195 * Check known_hosts files for deprecated keys under other names. Returns 0 2196 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2197 * exist under names other than the active hostname/IP. 2198 */ 2199 static int 2200 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2201 { 2202 size_t i; 2203 int r; 2204 2205 debug2_f("checking for %zu deprecated keys", ctx->nold); 2206 for (i = 0; i < options.num_user_hostfiles; i++) { 2207 debug3_f("searching %s for %s / %s", 2208 options.user_hostfiles[i], ctx->host_str, 2209 ctx->ip_str ? ctx->ip_str : "(none)"); 2210 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2211 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2212 HKF_WANT_PARSE_KEY, 0)) != 0) { 2213 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2214 debug_f("hostkeys file %s does not exist", 2215 options.user_hostfiles[i]); 2216 continue; 2217 } 2218 error_fr(r, "hostkeys_foreach failed for %s", 2219 options.user_hostfiles[i]); 2220 return -1; 2221 } 2222 } 2223 return 0; 2224 } 2225 2226 static void 2227 hostkey_change_preamble(LogLevel loglevel) 2228 { 2229 do_log2(loglevel, "The server has updated its host keys."); 2230 do_log2(loglevel, "These changes were verified by the server's " 2231 "existing trusted key."); 2232 } 2233 2234 static void 2235 update_known_hosts(struct hostkeys_update_ctx *ctx) 2236 { 2237 int r, was_raw = 0, first = 1; 2238 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2239 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2240 char *fp, *response; 2241 size_t i; 2242 struct stat sb; 2243 2244 for (i = 0; i < ctx->nkeys; i++) { 2245 if (!ctx->keys_verified[i]) 2246 continue; 2247 if ((fp = sshkey_fingerprint(ctx->keys[i], 2248 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2249 fatal_f("sshkey_fingerprint failed"); 2250 if (first && asking) 2251 hostkey_change_preamble(loglevel); 2252 do_log2(loglevel, "Learned new hostkey: %s %s", 2253 sshkey_type(ctx->keys[i]), fp); 2254 first = 0; 2255 free(fp); 2256 } 2257 for (i = 0; i < ctx->nold; i++) { 2258 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2259 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2260 fatal_f("sshkey_fingerprint failed"); 2261 if (first && asking) 2262 hostkey_change_preamble(loglevel); 2263 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2264 sshkey_type(ctx->old_keys[i]), fp); 2265 first = 0; 2266 free(fp); 2267 } 2268 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2269 if (get_saved_tio() != NULL) { 2270 leave_raw_mode(1); 2271 was_raw = 1; 2272 } 2273 response = NULL; 2274 for (i = 0; !quit_pending && i < 3; i++) { 2275 free(response); 2276 response = read_passphrase("Accept updated hostkeys? " 2277 "(yes/no): ", RP_ECHO); 2278 if (response != NULL && strcasecmp(response, "yes") == 0) 2279 break; 2280 else if (quit_pending || response == NULL || 2281 strcasecmp(response, "no") == 0) { 2282 options.update_hostkeys = 0; 2283 break; 2284 } else { 2285 do_log2(loglevel, "Please enter " 2286 "\"yes\" or \"no\""); 2287 } 2288 } 2289 if (quit_pending || i >= 3 || response == NULL) 2290 options.update_hostkeys = 0; 2291 free(response); 2292 if (was_raw) 2293 enter_raw_mode(1); 2294 } 2295 if (options.update_hostkeys == 0) 2296 return; 2297 /* 2298 * Now that all the keys are verified, we can go ahead and replace 2299 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2300 * cancel the operation). 2301 */ 2302 for (i = 0; i < options.num_user_hostfiles; i++) { 2303 /* 2304 * NB. keys are only added to hostfiles[0], for the rest we 2305 * just delete the hostname entries. 2306 */ 2307 if (stat(options.user_hostfiles[i], &sb) != 0) { 2308 if (errno == ENOENT) { 2309 debug_f("known hosts file %s does not " 2310 "exist", options.user_hostfiles[i]); 2311 } else { 2312 error_f("known hosts file %s " 2313 "inaccessible: %s", 2314 options.user_hostfiles[i], strerror(errno)); 2315 } 2316 continue; 2317 } 2318 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2319 ctx->host_str, ctx->ip_str, 2320 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2321 options.hash_known_hosts, 0, 2322 options.fingerprint_hash)) != 0) { 2323 error_fr(r, "hostfile_replace_entries failed for %s", 2324 options.user_hostfiles[i]); 2325 } 2326 } 2327 } 2328 2329 static void 2330 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2331 u_int32_t seq, void *_ctx) 2332 { 2333 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2334 size_t i, ndone; 2335 struct sshbuf *signdata; 2336 int r, plaintype; 2337 const u_char *sig; 2338 const char *rsa_kexalg = NULL; 2339 char *alg = NULL; 2340 size_t siglen; 2341 2342 if (ctx->nnew == 0) 2343 fatal_f("ctx->nnew == 0"); /* sanity */ 2344 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2345 error("Server failed to confirm ownership of " 2346 "private host keys"); 2347 hostkeys_update_ctx_free(ctx); 2348 return; 2349 } 2350 if (sshkey_type_plain(sshkey_type_from_name( 2351 ssh->kex->hostkey_alg)) == KEY_RSA) 2352 rsa_kexalg = ssh->kex->hostkey_alg; 2353 if ((signdata = sshbuf_new()) == NULL) 2354 fatal_f("sshbuf_new failed"); 2355 /* 2356 * Expect a signature for each of the ctx->nnew private keys we 2357 * haven't seen before. They will be in the same order as the 2358 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2359 */ 2360 for (ndone = i = 0; i < ctx->nkeys; i++) { 2361 if (ctx->keys_match[i]) 2362 continue; 2363 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2364 /* Prepare data to be signed: session ID, unique string, key */ 2365 sshbuf_reset(signdata); 2366 if ( (r = sshbuf_put_cstring(signdata, 2367 "hostkeys-prove-00@openssh.com")) != 0 || 2368 (r = sshbuf_put_stringb(signdata, 2369 ssh->kex->session_id)) != 0 || 2370 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2371 fatal_fr(r, "compose signdata"); 2372 /* Extract and verify signature */ 2373 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2374 error_fr(r, "parse sig"); 2375 goto out; 2376 } 2377 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2378 error_fr(r, "server gave unintelligible signature " 2379 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2380 goto out; 2381 } 2382 /* 2383 * Special case for RSA keys: if a RSA hostkey was negotiated, 2384 * then use its signature type for verification of RSA hostkey 2385 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2386 */ 2387 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2388 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2389 debug_f("server used untrusted RSA signature algorithm " 2390 "%s for key %zu, disregarding", alg, i); 2391 free(alg); 2392 /* zap the key from the list */ 2393 sshkey_free(ctx->keys[i]); 2394 ctx->keys[i] = NULL; 2395 ndone++; 2396 continue; 2397 } 2398 debug3_f("verify %s key %zu using sigalg %s", 2399 sshkey_type(ctx->keys[i]), i, alg); 2400 free(alg); 2401 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2402 sshbuf_ptr(signdata), sshbuf_len(signdata), 2403 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2404 error_fr(r, "server gave bad signature for %s key %zu", 2405 sshkey_type(ctx->keys[i]), i); 2406 goto out; 2407 } 2408 /* Key is good. Mark it as 'seen' */ 2409 ctx->keys_verified[i] = 1; 2410 ndone++; 2411 } 2412 /* Shouldn't happen */ 2413 if (ndone != ctx->nnew) 2414 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2415 if ((r = sshpkt_get_end(ssh)) != 0) { 2416 error_f("protocol error"); 2417 goto out; 2418 } 2419 2420 /* Make the edits to known_hosts */ 2421 update_known_hosts(ctx); 2422 out: 2423 hostkeys_update_ctx_free(ctx); 2424 hostkeys_update_complete = 1; 2425 client_repledge(); 2426 } 2427 2428 /* 2429 * Handle hostkeys-00@openssh.com global request to inform the client of all 2430 * the server's hostkeys. The keys are checked against the user's 2431 * HostkeyAlgorithms preference before they are accepted. 2432 */ 2433 static int 2434 client_input_hostkeys(struct ssh *ssh) 2435 { 2436 const u_char *blob = NULL; 2437 size_t i, len = 0; 2438 struct sshbuf *buf = NULL; 2439 struct sshkey *key = NULL, **tmp; 2440 int r, prove_sent = 0; 2441 char *fp; 2442 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2443 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2444 struct hostkeys_update_ctx *ctx = NULL; 2445 u_int want; 2446 2447 if (hostkeys_seen) 2448 fatal_f("server already sent hostkeys"); 2449 if (!can_update_hostkeys()) 2450 return 1; 2451 hostkeys_seen = 1; 2452 2453 ctx = xcalloc(1, sizeof(*ctx)); 2454 while (ssh_packet_remaining(ssh) > 0) { 2455 sshkey_free(key); 2456 key = NULL; 2457 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2458 error_fr(r, "parse key"); 2459 goto out; 2460 } 2461 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2462 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2463 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2464 "convert key"); 2465 continue; 2466 } 2467 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2468 SSH_FP_DEFAULT); 2469 debug3_f("received %s key %s", sshkey_type(key), fp); 2470 free(fp); 2471 2472 if (!hostkey_accepted_by_hostkeyalgs(key)) { 2473 debug3_f("%s key not permitted by " 2474 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2475 continue; 2476 } 2477 /* Skip certs */ 2478 if (sshkey_is_cert(key)) { 2479 debug3_f("%s key is a certificate; skipping", 2480 sshkey_ssh_name(key)); 2481 continue; 2482 } 2483 /* Ensure keys are unique */ 2484 for (i = 0; i < ctx->nkeys; i++) { 2485 if (sshkey_equal(key, ctx->keys[i])) { 2486 error_f("received duplicated %s host key", 2487 sshkey_ssh_name(key)); 2488 goto out; 2489 } 2490 } 2491 /* Key is good, record it */ 2492 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2493 sizeof(*ctx->keys))) == NULL) 2494 fatal_f("recallocarray failed nkeys = %zu", 2495 ctx->nkeys); 2496 ctx->keys = tmp; 2497 ctx->keys[ctx->nkeys++] = key; 2498 key = NULL; 2499 } 2500 2501 if (ctx->nkeys == 0) { 2502 debug_f("server sent no hostkeys"); 2503 goto out; 2504 } 2505 2506 if ((ctx->keys_match = calloc(ctx->nkeys, 2507 sizeof(*ctx->keys_match))) == NULL || 2508 (ctx->keys_verified = calloc(ctx->nkeys, 2509 sizeof(*ctx->keys_verified))) == NULL) 2510 fatal_f("calloc failed"); 2511 2512 get_hostfile_hostname_ipaddr(host, 2513 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2514 options.port, &ctx->host_str, 2515 options.check_host_ip ? &ctx->ip_str : NULL); 2516 2517 /* Find which keys we already know about. */ 2518 for (i = 0; i < options.num_user_hostfiles; i++) { 2519 debug_f("searching %s for %s / %s", 2520 options.user_hostfiles[i], ctx->host_str, 2521 ctx->ip_str ? ctx->ip_str : "(none)"); 2522 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2523 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2524 HKF_WANT_PARSE_KEY, 0)) != 0) { 2525 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2526 debug_f("hostkeys file %s does not exist", 2527 options.user_hostfiles[i]); 2528 continue; 2529 } 2530 error_fr(r, "hostkeys_foreach failed for %s", 2531 options.user_hostfiles[i]); 2532 goto out; 2533 } 2534 } 2535 2536 /* Figure out if we have any new keys to add */ 2537 ctx->nnew = ctx->nincomplete = 0; 2538 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2539 for (i = 0; i < ctx->nkeys; i++) { 2540 if (ctx->keys_match[i] == 0) 2541 ctx->nnew++; 2542 if ((ctx->keys_match[i] & want) != want) 2543 ctx->nincomplete++; 2544 } 2545 2546 debug3_f("%zu server keys: %zu new, %zu retained, " 2547 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2548 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2549 ctx->nincomplete, ctx->nold); 2550 2551 if (ctx->nnew == 0 && ctx->nold == 0) { 2552 debug_f("no new or deprecated keys from server"); 2553 goto out; 2554 } 2555 2556 /* Various reasons why we cannot proceed with the update */ 2557 if (ctx->complex_hostspec) { 2558 debug_f("CA/revocation marker, manual host list or wildcard " 2559 "host pattern found, skipping UserKnownHostsFile update"); 2560 goto out; 2561 } 2562 if (ctx->other_name_seen) { 2563 debug_f("host key found matching a different name/address, " 2564 "skipping UserKnownHostsFile update"); 2565 goto out; 2566 } 2567 /* 2568 * If removing keys, check whether they appear under different 2569 * names/addresses and refuse to proceed if they do. This avoids 2570 * cases such as hosts with multiple names becoming inconsistent 2571 * with regards to CheckHostIP entries. 2572 * XXX UpdateHostkeys=force to override this (and other) checks? 2573 */ 2574 if (ctx->nold != 0) { 2575 if (check_old_keys_othernames(ctx) != 0) 2576 goto out; /* error already logged */ 2577 if (ctx->old_key_seen) { 2578 debug_f("key(s) for %s%s%s exist under other names; " 2579 "skipping UserKnownHostsFile update", 2580 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2581 ctx->ip_str == NULL ? "" : ctx->ip_str); 2582 goto out; 2583 } 2584 } 2585 2586 if (ctx->nnew == 0) { 2587 /* 2588 * We have some keys to remove or fix matching for. 2589 * We can proceed to do this without requiring a fresh proof 2590 * from the server. 2591 */ 2592 update_known_hosts(ctx); 2593 goto out; 2594 } 2595 /* 2596 * We have received previously-unseen keys from the server. 2597 * Ask the server to confirm ownership of the private halves. 2598 */ 2599 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2600 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2601 (r = sshpkt_put_cstring(ssh, 2602 "hostkeys-prove-00@openssh.com")) != 0 || 2603 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2604 fatal_fr(r, "prepare hostkeys-prove"); 2605 if ((buf = sshbuf_new()) == NULL) 2606 fatal_f("sshbuf_new"); 2607 for (i = 0; i < ctx->nkeys; i++) { 2608 if (ctx->keys_match[i]) 2609 continue; 2610 sshbuf_reset(buf); 2611 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2612 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2613 fatal_fr(r, "assemble hostkeys-prove"); 2614 } 2615 if ((r = sshpkt_send(ssh)) != 0) 2616 fatal_fr(r, "send hostkeys-prove"); 2617 client_register_global_confirm( 2618 client_global_hostkeys_prove_confirm, ctx); 2619 ctx = NULL; /* will be freed in callback */ 2620 prove_sent = 1; 2621 2622 /* Success */ 2623 out: 2624 hostkeys_update_ctx_free(ctx); 2625 sshkey_free(key); 2626 sshbuf_free(buf); 2627 if (!prove_sent) { 2628 /* UpdateHostkeys handling completed */ 2629 hostkeys_update_complete = 1; 2630 client_repledge(); 2631 } 2632 /* 2633 * NB. Return success for all cases. The server doesn't need to know 2634 * what the client does with its hosts file. 2635 */ 2636 return 1; 2637 } 2638 2639 static int 2640 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2641 { 2642 char *rtype; 2643 u_char want_reply; 2644 int r, success = 0; 2645 2646 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2647 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2648 goto out; 2649 debug("client_input_global_request: rtype %s want_reply %d", 2650 rtype, want_reply); 2651 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2652 success = client_input_hostkeys(ssh); 2653 if (want_reply) { 2654 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2655 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2656 (r = sshpkt_send(ssh)) != 0 || 2657 (r = ssh_packet_write_wait(ssh)) != 0) 2658 goto out; 2659 } 2660 r = 0; 2661 out: 2662 free(rtype); 2663 return r; 2664 } 2665 2666 static void 2667 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2668 { 2669 int r; 2670 2671 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2672 channel_request_start(ssh, id, "env", 0); 2673 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2674 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2675 (r = sshpkt_send(ssh)) != 0) 2676 fatal_fr(r, "send setenv"); 2677 } 2678 2679 void 2680 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2681 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2682 char **env) 2683 { 2684 size_t i, j, len; 2685 int matched, r; 2686 char *name, *val; 2687 Channel *c = NULL; 2688 2689 debug2_f("id %d", id); 2690 2691 if ((c = channel_lookup(ssh, id)) == NULL) 2692 fatal_f("channel %d: unknown channel", id); 2693 2694 ssh_packet_set_interactive(ssh, want_tty, 2695 options.ip_qos_interactive, options.ip_qos_bulk); 2696 2697 if (want_tty) { 2698 struct winsize ws; 2699 2700 /* Store window size in the packet. */ 2701 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2702 memset(&ws, 0, sizeof(ws)); 2703 2704 channel_request_start(ssh, id, "pty-req", 1); 2705 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2706 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2707 != 0 || 2708 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2709 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2710 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2711 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2712 fatal_fr(r, "build pty-req"); 2713 if (tiop == NULL) 2714 tiop = get_saved_tio(); 2715 ssh_tty_make_modes(ssh, -1, tiop); 2716 if ((r = sshpkt_send(ssh)) != 0) 2717 fatal_fr(r, "send pty-req"); 2718 /* XXX wait for reply */ 2719 c->client_tty = 1; 2720 } 2721 2722 /* Transfer any environment variables from client to server */ 2723 if (options.num_send_env != 0 && env != NULL) { 2724 debug("Sending environment."); 2725 for (i = 0; env[i] != NULL; i++) { 2726 /* Split */ 2727 name = xstrdup(env[i]); 2728 if ((val = strchr(name, '=')) == NULL) { 2729 free(name); 2730 continue; 2731 } 2732 *val++ = '\0'; 2733 2734 matched = 0; 2735 for (j = 0; j < options.num_send_env; j++) { 2736 if (match_pattern(name, options.send_env[j])) { 2737 matched = 1; 2738 break; 2739 } 2740 } 2741 if (!matched) { 2742 debug3("Ignored env %s", name); 2743 free(name); 2744 continue; 2745 } 2746 client_send_env(ssh, id, name, val); 2747 free(name); 2748 } 2749 } 2750 for (i = 0; i < options.num_setenv; i++) { 2751 /* Split */ 2752 name = xstrdup(options.setenv[i]); 2753 if ((val = strchr(name, '=')) == NULL) { 2754 free(name); 2755 continue; 2756 } 2757 *val++ = '\0'; 2758 client_send_env(ssh, id, name, val); 2759 free(name); 2760 } 2761 2762 len = sshbuf_len(cmd); 2763 if (len > 0) { 2764 if (len > 900) 2765 len = 900; 2766 if (want_subsystem) { 2767 debug("Sending subsystem: %.*s", 2768 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2769 channel_request_start(ssh, id, "subsystem", 1); 2770 client_expect_confirm(ssh, id, "subsystem", 2771 CONFIRM_CLOSE); 2772 } else { 2773 debug("Sending command: %.*s", 2774 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2775 channel_request_start(ssh, id, "exec", 1); 2776 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2777 } 2778 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2779 (r = sshpkt_send(ssh)) != 0) 2780 fatal_fr(r, "send command"); 2781 } else { 2782 channel_request_start(ssh, id, "shell", 1); 2783 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2784 if ((r = sshpkt_send(ssh)) != 0) 2785 fatal_fr(r, "send shell"); 2786 } 2787 2788 session_setup_complete = 1; 2789 client_repledge(); 2790 } 2791 2792 static void 2793 client_init_dispatch(struct ssh *ssh) 2794 { 2795 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2796 2797 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2798 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2799 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2800 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2801 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2802 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2803 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2804 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2805 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2806 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2807 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2808 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2809 2810 /* rekeying */ 2811 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2812 2813 /* global request reply messages */ 2814 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2815 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2816 } 2817 2818 void 2819 client_stop_mux(void) 2820 { 2821 if (options.control_path != NULL && muxserver_sock != -1) 2822 unlink(options.control_path); 2823 /* 2824 * If we are in persist mode, or don't have a shell, signal that we 2825 * should close when all active channels are closed. 2826 */ 2827 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2828 session_closed = 1; 2829 setproctitle("[stopped mux]"); 2830 } 2831 } 2832 2833 /* client specific fatal cleanup */ 2834 void 2835 cleanup_exit(int i) 2836 { 2837 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2838 if (options.control_path != NULL && muxserver_sock != -1) 2839 unlink(options.control_path); 2840 ssh_kill_proxy_command(); 2841 _exit(i); 2842 } 2843