1 /* $OpenBSD: clientloop.c,v 1.415 2025/09/25 06:23:19 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 #include <sys/stat.h> 67 #include <sys/socket.h> 68 #include <sys/time.h> 69 70 #include <ctype.h> 71 #include <errno.h> 72 #include <paths.h> 73 #include <poll.h> 74 #include <signal.h> 75 #include <stdio.h> 76 #include <stdlib.h> 77 #include <string.h> 78 #include <stdarg.h> 79 #include <termios.h> 80 #include <pwd.h> 81 #include <unistd.h> 82 #include <limits.h> 83 84 #include "openbsd-compat/sys-queue.h" 85 #include "xmalloc.h" 86 #include "ssh.h" 87 #include "ssh2.h" 88 #include "packet.h" 89 #include "sshbuf.h" 90 #include "compat.h" 91 #include "channels.h" 92 #include "dispatch.h" 93 #include "sshkey.h" 94 #include "cipher.h" 95 #include "kex.h" 96 #include "myproposal.h" 97 #include "log.h" 98 #include "misc.h" 99 #include "readconf.h" 100 #include "clientloop.h" 101 #include "sshconnect.h" 102 #include "authfd.h" 103 #include "atomicio.h" 104 #include "sshpty.h" 105 #include "match.h" 106 #include "msg.h" 107 #include "ssherr.h" 108 #include "hostfile.h" 109 110 /* Permitted RSA signature algorithms for UpdateHostkeys proofs */ 111 #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256" 112 113 /* Uncertainty (in percent) of keystroke timing intervals */ 114 #define SSH_KEYSTROKE_TIMING_FUZZ 10 115 116 /* 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 siginfo_received = 0; 143 static volatile sig_atomic_t received_signal = 0; /* exit signals */ 144 145 /* Time when backgrounded control master using ControlPersist should exit */ 146 static time_t control_persist_exit_time = 0; 147 148 /* Common data for the client loop code. */ 149 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ 150 static int last_was_cr; /* Last character was a newline. */ 151 static int exit_status; /* Used to store the command exit status. */ 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 static void quit_message(const char *fmt, ...) 190 __attribute__((__format__ (printf, 1, 2))); 191 192 static void 193 quit_message(const char *fmt, ...) 194 { 195 char *msg, *fmt2; 196 va_list args; 197 xasprintf(&fmt2, "%s\r\n", fmt); 198 199 va_start(args, fmt); 200 xvasprintf(&msg, fmt2, args); 201 va_end(args); 202 203 (void)atomicio(vwrite, STDERR_FILENO, msg, strlen(msg)); 204 free(msg); 205 free(fmt2); 206 207 quit_pending = 1; 208 } 209 210 /* 211 * Signal handler for the window change signal (SIGWINCH). This just sets a 212 * flag indicating that the window has changed. 213 */ 214 static void 215 window_change_handler(int sig) 216 { 217 received_window_change_signal = 1; 218 } 219 220 #ifdef SIGINFO 221 /* Signal handler for SIGINFO */ 222 static void 223 siginfo_handler(int sig) 224 { 225 siginfo_received = 1; 226 } 227 #endif 228 229 /* 230 * Signal handler for signals that cause the program to terminate. These 231 * signals must be trapped to restore terminal modes. 232 */ 233 static void 234 signal_handler(int sig) 235 { 236 received_signal = sig; 237 quit_pending = 1; 238 } 239 240 /* 241 * Sets control_persist_exit_time to the absolute time when the 242 * backgrounded control master should exit due to expiry of the 243 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded 244 * control master process, or if there is no ControlPersist timeout. 245 */ 246 static void 247 set_control_persist_exit_time(struct ssh *ssh) 248 { 249 if (muxserver_sock == -1 || !options.control_persist 250 || options.control_persist_timeout == 0) { 251 /* not using a ControlPersist timeout */ 252 control_persist_exit_time = 0; 253 } else if (channel_still_open(ssh)) { 254 /* some client connections are still open */ 255 if (control_persist_exit_time > 0) 256 debug2_f("cancel scheduled exit"); 257 control_persist_exit_time = 0; 258 } else if (control_persist_exit_time <= 0) { 259 /* a client connection has recently closed */ 260 control_persist_exit_time = monotime() + 261 (time_t)options.control_persist_timeout; 262 debug2_f("schedule exit in %d seconds", 263 options.control_persist_timeout); 264 } 265 /* else we are already counting down to the timeout */ 266 } 267 268 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_" 269 static int 270 client_x11_display_valid(const char *display) 271 { 272 size_t i, dlen; 273 274 if (display == NULL) 275 return 0; 276 277 dlen = strlen(display); 278 for (i = 0; i < dlen; i++) { 279 if (!isalnum((u_char)display[i]) && 280 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) { 281 debug("Invalid character '%c' in DISPLAY", display[i]); 282 return 0; 283 } 284 } 285 return 1; 286 } 287 288 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1" 289 #define X11_TIMEOUT_SLACK 60 290 int 291 client_x11_get_proto(struct ssh *ssh, const char *display, 292 const char *xauth_path, u_int trusted, u_int timeout, 293 char **_proto, char **_data) 294 { 295 char *cmd, line[512], xdisplay[512]; 296 char xauthfile[PATH_MAX], xauthdir[PATH_MAX]; 297 static char proto[512], data[512]; 298 FILE *f; 299 int got_data = 0, generated = 0, do_unlink = 0, r; 300 struct stat st; 301 u_int now, x11_timeout_real; 302 303 *_proto = proto; 304 *_data = data; 305 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0'; 306 307 if (!client_x11_display_valid(display)) { 308 if (display != NULL) 309 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding", 310 display); 311 return -1; 312 } 313 if (xauth_path != NULL && stat(xauth_path, &st) == -1) { 314 debug("No xauth program."); 315 xauth_path = NULL; 316 } 317 318 if (xauth_path != NULL) { 319 /* 320 * Handle FamilyLocal case where $DISPLAY does 321 * not match an authorization entry. For this we 322 * just try "xauth list unix:displaynum.screennum". 323 * XXX: "localhost" match to determine FamilyLocal 324 * is not perfect. 325 */ 326 if (strncmp(display, "localhost:", 10) == 0) { 327 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s", 328 display + 10)) < 0 || 329 (size_t)r >= sizeof(xdisplay)) { 330 error_f("display name too long"); 331 return -1; 332 } 333 display = xdisplay; 334 } 335 if (trusted == 0) { 336 /* 337 * Generate an untrusted X11 auth cookie. 338 * 339 * The authentication cookie should briefly outlive 340 * ssh's willingness to forward X11 connections to 341 * avoid nasty fail-open behaviour in the X server. 342 */ 343 mktemp_proto(xauthdir, sizeof(xauthdir)); 344 if (mkdtemp(xauthdir) == NULL) { 345 error_f("mkdtemp: %s", strerror(errno)); 346 return -1; 347 } 348 do_unlink = 1; 349 if ((r = snprintf(xauthfile, sizeof(xauthfile), 350 "%s/xauthfile", xauthdir)) < 0 || 351 (size_t)r >= sizeof(xauthfile)) { 352 error_f("xauthfile path too long"); 353 rmdir(xauthdir); 354 return -1; 355 } 356 357 if (timeout == 0) { 358 /* auth doesn't time out */ 359 xasprintf(&cmd, "%s -f %s generate %s %s " 360 "untrusted 2>%s", 361 xauth_path, xauthfile, display, 362 SSH_X11_PROTO, _PATH_DEVNULL); 363 } else { 364 /* Add some slack to requested expiry */ 365 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK) 366 x11_timeout_real = timeout + 367 X11_TIMEOUT_SLACK; 368 else { 369 /* Don't overflow on long timeouts */ 370 x11_timeout_real = UINT_MAX; 371 } 372 xasprintf(&cmd, "%s -f %s generate %s %s " 373 "untrusted timeout %u 2>%s", 374 xauth_path, xauthfile, display, 375 SSH_X11_PROTO, x11_timeout_real, 376 _PATH_DEVNULL); 377 } 378 debug2_f("xauth command: %s", cmd); 379 380 if (timeout != 0 && x11_refuse_time == 0) { 381 now = monotime() + 1; 382 if (SSH_TIME_T_MAX - timeout < now) 383 x11_refuse_time = SSH_TIME_T_MAX; 384 else 385 x11_refuse_time = now + timeout; 386 channel_set_x11_refuse_time(ssh, 387 x11_refuse_time); 388 } 389 if (system(cmd) == 0) 390 generated = 1; 391 free(cmd); 392 } 393 394 /* 395 * When in untrusted mode, we read the cookie only if it was 396 * successfully generated as an untrusted one in the step 397 * above. 398 */ 399 if (trusted || generated) { 400 xasprintf(&cmd, 401 "%s %s%s list %s 2>" _PATH_DEVNULL, 402 xauth_path, 403 generated ? "-f " : "" , 404 generated ? xauthfile : "", 405 display); 406 debug2("x11_get_proto: %s", cmd); 407 f = popen(cmd, "r"); 408 if (f && fgets(line, sizeof(line), f) && 409 sscanf(line, "%*s %511s %511s", proto, data) == 2) 410 got_data = 1; 411 if (f) 412 pclose(f); 413 free(cmd); 414 } 415 } 416 417 if (do_unlink) { 418 unlink(xauthfile); 419 rmdir(xauthdir); 420 } 421 422 /* Don't fall back to fake X11 data for untrusted forwarding */ 423 if (!trusted && !got_data) { 424 error("Warning: untrusted X11 forwarding setup failed: " 425 "xauth key data not generated"); 426 return -1; 427 } 428 429 /* 430 * If we didn't get authentication data, just make up some 431 * data. The forwarding code will check the validity of the 432 * response anyway, and substitute this data. The X11 433 * server, however, will ignore this fake data and use 434 * whatever authentication mechanisms it was using otherwise 435 * for the local connection. 436 */ 437 if (!got_data) { 438 u_int8_t rnd[16]; 439 u_int i; 440 441 logit("Warning: No xauth data; " 442 "using fake authentication data for X11 forwarding."); 443 strlcpy(proto, SSH_X11_PROTO, sizeof proto); 444 arc4random_buf(rnd, sizeof(rnd)); 445 for (i = 0; i < sizeof(rnd); i++) { 446 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", 447 rnd[i]); 448 } 449 } 450 451 return 0; 452 } 453 454 /* 455 * Checks if the client window has changed, and sends a packet about it to 456 * the server if so. The actual change is detected elsewhere (by a software 457 * interrupt on Unix); this just checks the flag and sends a message if 458 * appropriate. 459 */ 460 461 static void 462 client_check_window_change(struct ssh *ssh) 463 { 464 if (!received_window_change_signal) 465 return; 466 received_window_change_signal = 0; 467 debug2_f("changed"); 468 channel_send_window_changes(ssh); 469 } 470 471 static int 472 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh) 473 { 474 struct global_confirm *gc; 475 476 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL) 477 return 0; 478 if (gc->cb != NULL) 479 gc->cb(ssh, type, seq, gc->ctx); 480 if (--gc->ref_count <= 0) { 481 TAILQ_REMOVE(&global_confirms, gc, entry); 482 freezero(gc, sizeof(*gc)); 483 } 484 485 ssh_packet_set_alive_timeouts(ssh, 0); 486 return 0; 487 } 488 489 static void 490 schedule_server_alive_check(void) 491 { 492 if (options.server_alive_interval > 0) 493 server_alive_time = monotime() + options.server_alive_interval; 494 } 495 496 static void 497 server_alive_check(struct ssh *ssh) 498 { 499 int r; 500 501 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) { 502 logit("Timeout, server %s not responding.", host); 503 cleanup_exit(255); 504 } 505 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 506 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 || 507 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */ 508 (r = sshpkt_send(ssh)) != 0) 509 fatal_fr(r, "send packet"); 510 /* Insert an empty placeholder to maintain ordering */ 511 client_register_global_confirm(NULL, NULL); 512 schedule_server_alive_check(); 513 } 514 515 /* Try to send a dummy keystroke */ 516 static int 517 send_chaff(struct ssh *ssh) 518 { 519 int r; 520 521 if (ssh->kex == NULL || (ssh->kex->flags & KEX_HAS_PING) == 0) 522 return 0; 523 /* XXX probabilistically send chaff? */ 524 /* 525 * a SSH2_MSG_CHANNEL_DATA payload is 9 bytes: 526 * 4 bytes channel ID + 4 bytes string length + 1 byte string data 527 * simulate that here. 528 */ 529 if ((r = sshpkt_start(ssh, SSH2_MSG_PING)) != 0 || 530 (r = sshpkt_put_cstring(ssh, "PING!")) != 0 || 531 (r = sshpkt_send(ssh)) != 0) 532 fatal_fr(r, "send packet"); 533 return 1; 534 } 535 536 /* Sets the next interval to send a keystroke or chaff packet */ 537 static void 538 set_next_interval(const struct timespec *now, struct timespec *next_interval, 539 u_int interval_ms, int starting) 540 { 541 struct timespec tmp; 542 long long interval_ns, fuzz_ns; 543 static long long rate_fuzz; 544 545 interval_ns = interval_ms * (1000LL * 1000); 546 fuzz_ns = (interval_ns * SSH_KEYSTROKE_TIMING_FUZZ) / 100; 547 /* Center fuzz around requested interval */ 548 if (fuzz_ns > INT_MAX) 549 fuzz_ns = INT_MAX; 550 if (fuzz_ns > interval_ns) { 551 /* Shouldn't happen */ 552 fatal_f("internal error: fuzz %u%% %lldns > interval %lldns", 553 SSH_KEYSTROKE_TIMING_FUZZ, fuzz_ns, interval_ns); 554 } 555 /* 556 * Randomise the keystroke/chaff intervals in two ways: 557 * 1. Each interval has some random jitter applied to make the 558 * interval-to-interval time unpredictable. 559 * 2. The overall interval rate is also randomly perturbed for each 560 * chaffing session to make the average rate unpredictable. 561 */ 562 if (starting) 563 rate_fuzz = arc4random_uniform(fuzz_ns); 564 interval_ns -= fuzz_ns; 565 interval_ns += arc4random_uniform(fuzz_ns) + rate_fuzz; 566 567 tmp.tv_sec = interval_ns / (1000 * 1000 * 1000); 568 tmp.tv_nsec = interval_ns % (1000 * 1000 * 1000); 569 570 timespecadd(now, &tmp, next_interval); 571 } 572 573 /* 574 * Performs keystroke timing obfuscation. Returns non-zero if the 575 * output fd should be polled. 576 */ 577 static int 578 obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout, 579 int channel_did_enqueue) 580 { 581 static int active; 582 static struct timespec next_interval, chaff_until; 583 struct timespec now, tmp; 584 int just_started = 0, had_keystroke = 0; 585 static unsigned long long nchaff; 586 char *stop_reason = NULL; 587 long long n; 588 589 monotime_ts(&now); 590 591 if (options.obscure_keystroke_timing_interval <= 0) 592 return 1; /* disabled in config */ 593 594 if (!channel_tty_open(ssh) || quit_pending) { 595 /* Stop if no channels left of we're waiting for one to close */ 596 stop_reason = "no active channels"; 597 } else if (ssh_packet_is_rekeying(ssh)) { 598 /* Stop if we're rekeying */ 599 stop_reason = "rekeying started"; 600 } else if (!ssh_packet_interactive_data_to_write(ssh) && 601 ssh_packet_have_data_to_write(ssh)) { 602 /* Stop if the output buffer has more than a few keystrokes */ 603 stop_reason = "output buffer filling"; 604 } else if (active && channel_did_enqueue && 605 ssh_packet_have_data_to_write(ssh)) { 606 /* Still in active mode and have a keystroke queued. */ 607 had_keystroke = 1; 608 } else if (active) { 609 if (timespeccmp(&now, &chaff_until, >=)) { 610 /* Stop if there have been no keystrokes for a while */ 611 stop_reason = "chaff time expired"; 612 } else if (timespeccmp(&now, &next_interval, >=) && 613 !ssh_packet_have_data_to_write(ssh)) { 614 /* If due to send but have no data, then send chaff */ 615 if (send_chaff(ssh)) 616 nchaff++; 617 } 618 } 619 620 if (stop_reason != NULL) { 621 if (active) { 622 debug3_f("stopping: %s (%llu chaff packets sent)", 623 stop_reason, nchaff); 624 active = 0; 625 } 626 return 1; 627 } 628 629 /* 630 * If we're in interactive mode, and only have a small amount 631 * of outbound data, then we assume that the user is typing 632 * interactively. In this case, start quantising outbound packets to 633 * fixed time intervals to hide inter-keystroke timing. 634 */ 635 if (!active && ssh_packet_interactive_data_to_write(ssh) && 636 channel_did_enqueue && ssh_packet_have_data_to_write(ssh)) { 637 debug3_f("starting: interval ~%dms", 638 options.obscure_keystroke_timing_interval); 639 just_started = had_keystroke = active = 1; 640 nchaff = 0; 641 set_next_interval(&now, &next_interval, 642 options.obscure_keystroke_timing_interval, 1); 643 } 644 645 /* Don't hold off if obfuscation inactive */ 646 if (!active) 647 return 1; 648 649 if (had_keystroke) { 650 /* 651 * Arrange to send chaff packets for a random interval after 652 * the last keystroke was sent. 653 */ 654 ms_to_timespec(&tmp, SSH_KEYSTROKE_CHAFF_MIN_MS + 655 arc4random_uniform(SSH_KEYSTROKE_CHAFF_RNG_MS)); 656 timespecadd(&now, &tmp, &chaff_until); 657 } 658 659 ptimeout_deadline_monotime_tsp(timeout, &next_interval); 660 661 if (just_started) 662 return 1; 663 664 /* Don't arm output fd for poll until the timing interval has elapsed... */ 665 if (timespeccmp(&now, &next_interval, <)) 666 /* ...unless there's x11 communication happening */ 667 return x11_channel_used_recently(ssh); 668 669 /* Calculate number of intervals missed since the last check */ 670 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000; 671 n += now.tv_nsec - next_interval.tv_nsec; 672 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000; 673 n = (n < 0) ? 1 : n + 1; 674 675 /* Advance to the next interval */ 676 set_next_interval(&now, &next_interval, 677 options.obscure_keystroke_timing_interval * n, 0); 678 return 1; 679 } 680 681 /* 682 * Waits until the client can do something (some data becomes available on 683 * one of the file descriptors). 684 */ 685 static void 686 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp, 687 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue, 688 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp) 689 { 690 struct timespec timeout; 691 int ret, oready; 692 u_int p; 693 694 *conn_in_readyp = *conn_out_readyp = 0; 695 696 /* Prepare channel poll. First two pollfd entries are reserved */ 697 ptimeout_init(&timeout); 698 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 699 if (*npfd_activep < 2) 700 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 701 702 /* channel_prepare_poll could have closed the last channel */ 703 if (session_closed && !channel_still_open(ssh) && 704 !ssh_packet_have_data_to_write(ssh)) { 705 /* clear events since we did not call poll() */ 706 for (p = 0; p < *npfd_activep; p++) 707 (*pfdp)[p].revents = 0; 708 return; 709 } 710 711 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue); 712 713 /* Monitor server connection on reserved pollfd entries */ 714 (*pfdp)[0].fd = connection_in; 715 (*pfdp)[0].events = POLLIN; 716 (*pfdp)[1].fd = connection_out; 717 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ? 718 POLLOUT : 0; 719 720 /* 721 * Wait for something to happen. This will suspend the process until 722 * some polled descriptor can be read, written, or has some other 723 * event pending, or a timeout expires. 724 */ 725 set_control_persist_exit_time(ssh); 726 if (control_persist_exit_time > 0) 727 ptimeout_deadline_monotime(&timeout, control_persist_exit_time); 728 if (options.server_alive_interval > 0) 729 ptimeout_deadline_monotime(&timeout, server_alive_time); 730 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 731 ptimeout_deadline_sec(&timeout, 732 ssh_packet_get_rekey_timeout(ssh)); 733 } 734 735 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp); 736 737 if (ret == -1) { 738 /* 739 * We have to clear the events because we return. 740 * We have to return, because the mainloop checks for the flags 741 * set by the signal handlers. 742 */ 743 for (p = 0; p < *npfd_activep; p++) 744 (*pfdp)[p].revents = 0; 745 if (errno == EINTR) 746 return; 747 /* Note: we might still have data in the buffers. */ 748 quit_message("poll: %s", strerror(errno)); 749 return; 750 } 751 752 *conn_in_readyp = (*pfdp)[0].revents != 0; 753 *conn_out_readyp = (*pfdp)[1].revents != 0; 754 755 if (options.server_alive_interval > 0 && !*conn_in_readyp && 756 monotime() >= server_alive_time) { 757 /* 758 * ServerAlive check is needed. We can't rely on the poll 759 * timing out since traffic on the client side such as port 760 * forwards can keep waking it up. 761 */ 762 server_alive_check(ssh); 763 } 764 } 765 766 static void 767 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr) 768 { 769 /* Flush stdout and stderr buffers. */ 770 if (sshbuf_len(bout) > 0) 771 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout), 772 sshbuf_len(bout)); 773 if (sshbuf_len(berr) > 0) 774 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr), 775 sshbuf_len(berr)); 776 777 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 778 779 sshbuf_reset(bin); 780 sshbuf_reset(bout); 781 sshbuf_reset(berr); 782 783 /* Send the suspend signal to the program itself. */ 784 kill(getpid(), SIGTSTP); 785 786 /* Reset window sizes in case they have changed */ 787 received_window_change_signal = 1; 788 789 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 790 } 791 792 static void 793 client_process_net_input(struct ssh *ssh) 794 { 795 int r; 796 797 /* 798 * Read input from the server, and add any such data to the buffer of 799 * the packet subsystem. 800 */ 801 schedule_server_alive_check(); 802 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 803 return; /* success */ 804 if (r == SSH_ERR_SYSTEM_ERROR) { 805 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK) 806 return; 807 if (errno == EPIPE) { 808 quit_message("Connection to %s closed by remote host.", 809 host); 810 return; 811 } 812 } 813 quit_message("Read from remote host %s: %s", host, ssh_err(r)); 814 } 815 816 static void 817 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) 818 { 819 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; 820 char errmsg[256]; 821 int r, tochan; 822 823 /* 824 * If a TTY was explicitly requested, then a failure to allocate 825 * one is fatal. 826 */ 827 if (cr->action == CONFIRM_TTY && 828 (options.request_tty == REQUEST_TTY_FORCE || 829 options.request_tty == REQUEST_TTY_YES)) 830 cr->action = CONFIRM_CLOSE; 831 832 /* XXX suppress on mux _client_ quietmode */ 833 tochan = options.log_level >= SYSLOG_LEVEL_ERROR && 834 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; 835 836 if (type == SSH2_MSG_CHANNEL_SUCCESS) { 837 debug2("%s request accepted on channel %d", 838 cr->request_type, c->self); 839 } else if (type == SSH2_MSG_CHANNEL_FAILURE) { 840 if (tochan) { 841 snprintf(errmsg, sizeof(errmsg), 842 "%s request failed\r\n", cr->request_type); 843 } else { 844 snprintf(errmsg, sizeof(errmsg), 845 "%s request failed on channel %d", 846 cr->request_type, c->self); 847 } 848 /* If error occurred on primary session channel, then exit */ 849 if (cr->action == CONFIRM_CLOSE && c->self == session_ident) 850 fatal("%s", errmsg); 851 /* 852 * If error occurred on mux client, append to 853 * their stderr. 854 */ 855 if (tochan) { 856 debug3_f("channel %d: mux request: %s", c->self, 857 cr->request_type); 858 if ((r = sshbuf_put(c->extended, errmsg, 859 strlen(errmsg))) != 0) 860 fatal_fr(r, "sshbuf_put"); 861 } else 862 error("%s", errmsg); 863 if (cr->action == CONFIRM_TTY) { 864 /* 865 * If a TTY allocation error occurred, then arrange 866 * for the correct TTY to leave raw mode. 867 */ 868 if (c->self == session_ident) 869 leave_raw_mode(0); 870 else 871 mux_tty_alloc_failed(ssh, c); 872 } else if (cr->action == CONFIRM_CLOSE) { 873 chan_read_failed(ssh, c); 874 chan_write_failed(ssh, c); 875 } 876 } 877 free(cr); 878 } 879 880 static void 881 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) 882 { 883 free(ctx); 884 } 885 886 void 887 client_expect_confirm(struct ssh *ssh, int id, const char *request, 888 enum confirm_action action) 889 { 890 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); 891 892 cr->request_type = request; 893 cr->action = action; 894 895 channel_register_status_confirm(ssh, id, client_status_confirm, 896 client_abandon_status_confirm, cr); 897 } 898 899 void 900 client_register_global_confirm(global_confirm_cb *cb, void *ctx) 901 { 902 struct global_confirm *gc, *last_gc; 903 904 /* Coalesce identical callbacks */ 905 last_gc = TAILQ_LAST(&global_confirms, global_confirms); 906 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { 907 if (++last_gc->ref_count >= INT_MAX) 908 fatal_f("last_gc->ref_count = %d", 909 last_gc->ref_count); 910 return; 911 } 912 913 gc = xcalloc(1, sizeof(*gc)); 914 gc->cb = cb; 915 gc->ctx = ctx; 916 gc->ref_count = 1; 917 TAILQ_INSERT_TAIL(&global_confirms, gc, entry); 918 } 919 920 /* 921 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com 922 * hostkey update request. 923 */ 924 static int 925 can_update_hostkeys(void) 926 { 927 if (hostkeys_update_complete) 928 return 0; 929 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && 930 options.batch_mode) 931 return 0; /* won't ask in batchmode, so don't even try */ 932 if (!options.update_hostkeys || options.num_user_hostfiles <= 0) 933 return 0; 934 return 1; 935 } 936 937 static void 938 client_repledge(void) 939 { 940 debug3_f("enter"); 941 942 /* Might be able to tighten pledge now that session is established */ 943 if (options.control_master || options.control_path != NULL || 944 options.forward_x11 || options.fork_after_authentication || 945 can_update_hostkeys() || 946 (session_ident != -1 && !session_setup_complete)) { 947 /* Can't tighten */ 948 return; 949 } 950 /* 951 * LocalCommand and UpdateHostkeys have finished, so can get rid of 952 * filesystem. 953 * 954 * XXX protocol allows a server can to change hostkeys during the 955 * connection at rekey time that could trigger a hostkeys update 956 * but AFAIK no implementations support this. Could improve by 957 * forcing known_hosts to be read-only or via unveil(2). 958 */ 959 if (options.num_local_forwards != 0 || 960 options.num_remote_forwards != 0 || 961 options.num_permitted_remote_opens != 0 || 962 options.enable_escape_commandline != 0) { 963 /* rfwd needs inet */ 964 debug("pledge: network"); 965 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 966 fatal_f("pledge(): %s", strerror(errno)); 967 } else if (options.forward_agent != 0) { 968 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */ 969 debug("pledge: agent"); 970 if (pledge(PLEDGE_EXTRA_INET "stdio unix proc tty", NULL) == -1) 971 fatal_f("pledge(): %s", strerror(errno)); 972 } else { 973 debug("pledge: fork"); 974 if (pledge(PLEDGE_EXTRA_INET "stdio proc tty", NULL) == -1) 975 fatal_f("pledge(): %s", strerror(errno)); 976 } 977 /* XXX further things to do: 978 * 979 * - might be able to get rid of proc if we kill ~^Z 980 * - ssh -N (no session) 981 * - stdio forwarding 982 * - sessions without tty 983 */ 984 } 985 986 static void 987 process_cmdline(struct ssh *ssh) 988 { 989 void (*handler)(int); 990 char *s, *cmd; 991 int ok, delete = 0, local = 0, remote = 0, dynamic = 0; 992 struct Forward fwd; 993 994 memset(&fwd, 0, sizeof(fwd)); 995 996 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 997 handler = ssh_signal(SIGINT, SIG_IGN); 998 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); 999 if (s == NULL) 1000 goto out; 1001 while (isspace((u_char)*s)) 1002 s++; 1003 if (*s == '-') 1004 s++; /* Skip cmdline '-', if any */ 1005 if (*s == '\0') 1006 goto out; 1007 1008 if (*s == 'h' || *s == 'H' || *s == '?') { 1009 logit("Commands:"); 1010 logit(" -L[bind_address:]port:host:hostport " 1011 "Request local forward"); 1012 logit(" -R[bind_address:]port:host:hostport " 1013 "Request remote forward"); 1014 logit(" -D[bind_address:]port " 1015 "Request dynamic forward"); 1016 logit(" -KL[bind_address:]port " 1017 "Cancel local forward"); 1018 logit(" -KR[bind_address:]port " 1019 "Cancel remote forward"); 1020 logit(" -KD[bind_address:]port " 1021 "Cancel dynamic forward"); 1022 if (!options.permit_local_command) 1023 goto out; 1024 logit(" !args " 1025 "Execute local command"); 1026 goto out; 1027 } 1028 1029 if (*s == '!' && options.permit_local_command) { 1030 s++; 1031 ssh_local_cmd(s); 1032 goto out; 1033 } 1034 1035 if (*s == 'K') { 1036 delete = 1; 1037 s++; 1038 } 1039 if (*s == 'L') 1040 local = 1; 1041 else if (*s == 'R') 1042 remote = 1; 1043 else if (*s == 'D') 1044 dynamic = 1; 1045 else { 1046 logit("Invalid command."); 1047 goto out; 1048 } 1049 1050 while (isspace((u_char)*++s)) 1051 ; 1052 1053 /* XXX update list of forwards in options */ 1054 if (delete) { 1055 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ 1056 if (!parse_forward(&fwd, s, 1, 0)) { 1057 logit("Bad forwarding close specification."); 1058 goto out; 1059 } 1060 if (remote) 1061 ok = channel_request_rforward_cancel(ssh, &fwd) == 0; 1062 else if (dynamic) 1063 ok = channel_cancel_lport_listener(ssh, &fwd, 1064 0, &options.fwd_opts) > 0; 1065 else 1066 ok = channel_cancel_lport_listener(ssh, &fwd, 1067 CHANNEL_CANCEL_PORT_STATIC, 1068 &options.fwd_opts) > 0; 1069 if (!ok) { 1070 logit("Unknown port forwarding."); 1071 goto out; 1072 } 1073 logit("Canceled forwarding."); 1074 } else { 1075 /* -R specs can be both dynamic or not, so check both. */ 1076 if (remote) { 1077 if (!parse_forward(&fwd, s, 0, remote) && 1078 !parse_forward(&fwd, s, 1, remote)) { 1079 logit("Bad remote forwarding specification."); 1080 goto out; 1081 } 1082 } else if (!parse_forward(&fwd, s, dynamic, remote)) { 1083 logit("Bad local forwarding specification."); 1084 goto out; 1085 } 1086 if (local || dynamic) { 1087 if (!channel_setup_local_fwd_listener(ssh, &fwd, 1088 &options.fwd_opts)) { 1089 logit("Port forwarding failed."); 1090 goto out; 1091 } 1092 } else { 1093 if (channel_request_remote_forwarding(ssh, &fwd) < 0) { 1094 logit("Port forwarding failed."); 1095 goto out; 1096 } 1097 } 1098 logit("Forwarding port."); 1099 } 1100 1101 out: 1102 ssh_signal(SIGINT, handler); 1103 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1104 free(cmd); 1105 free(fwd.listen_host); 1106 free(fwd.listen_path); 1107 free(fwd.connect_host); 1108 free(fwd.connect_path); 1109 } 1110 1111 /* reasons to suppress output of an escape command in help output */ 1112 #define SUPPRESS_NEVER 0 /* never suppress, always show */ 1113 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ 1114 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ 1115 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ 1116 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/ 1117 struct escape_help_text { 1118 const char *cmd; 1119 const char *text; 1120 unsigned int flags; 1121 }; 1122 static struct escape_help_text esc_txt[] = { 1123 {".", "terminate session", SUPPRESS_MUXMASTER}, 1124 {".", "terminate connection (and any multiplexed sessions)", 1125 SUPPRESS_MUXCLIENT}, 1126 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, 1127 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE}, 1128 {"R", "request rekey", SUPPRESS_NEVER}, 1129 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, 1130 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, 1131 {"#", "list forwarded connections", SUPPRESS_NEVER}, 1132 {"&", "background ssh (when waiting for connections to terminate)", 1133 SUPPRESS_MUXCLIENT}, 1134 {"?", "this message", SUPPRESS_NEVER}, 1135 }; 1136 1137 static void 1138 print_escape_help(struct sshbuf *b, int escape_char, int mux_client, 1139 int using_stderr) 1140 { 1141 unsigned int i, suppress_flags; 1142 int r; 1143 1144 if ((r = sshbuf_putf(b, 1145 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0) 1146 fatal_fr(r, "sshbuf_putf"); 1147 1148 suppress_flags = 1149 (mux_client ? SUPPRESS_MUXCLIENT : 0) | 1150 (mux_client ? 0 : SUPPRESS_MUXMASTER) | 1151 (using_stderr ? 0 : SUPPRESS_SYSLOG) | 1152 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0); 1153 1154 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { 1155 if (esc_txt[i].flags & suppress_flags) 1156 continue; 1157 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n", 1158 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0) 1159 fatal_fr(r, "sshbuf_putf"); 1160 } 1161 1162 if ((r = sshbuf_putf(b, 1163 " %c%c - send the escape character by typing it twice\r\n" 1164 "(Note that escapes are only recognized immediately after " 1165 "newline.)\r\n", escape_char, escape_char)) != 0) 1166 fatal_fr(r, "sshbuf_putf"); 1167 } 1168 1169 /* 1170 * Process the characters one by one. 1171 */ 1172 static int 1173 process_escapes(struct ssh *ssh, Channel *c, 1174 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr, 1175 char *buf, int len) 1176 { 1177 pid_t pid; 1178 int r, bytes = 0; 1179 u_int i; 1180 u_char ch; 1181 char *s; 1182 struct escape_filter_ctx *efc; 1183 1184 if (c == NULL || c->filter_ctx == NULL || len <= 0) 1185 return 0; 1186 1187 efc = (struct escape_filter_ctx *)c->filter_ctx; 1188 1189 for (i = 0; i < (u_int)len; i++) { 1190 /* Get one character at a time. */ 1191 ch = buf[i]; 1192 1193 if (efc->escape_pending) { 1194 /* We have previously seen an escape character. */ 1195 /* Clear the flag now. */ 1196 efc->escape_pending = 0; 1197 1198 /* Process the escaped character. */ 1199 switch (ch) { 1200 case '.': 1201 /* Terminate the connection. */ 1202 if ((r = sshbuf_putf(berr, "%c.\r\n", 1203 efc->escape_char)) != 0) 1204 fatal_fr(r, "sshbuf_putf"); 1205 if (c && c->ctl_chan != -1) { 1206 channel_force_close(ssh, c, 1); 1207 return 0; 1208 } else 1209 quit_pending = 1; 1210 return -1; 1211 1212 case 'Z' - 64: 1213 /* XXX support this for mux clients */ 1214 if (c && c->ctl_chan != -1) { 1215 char b[16]; 1216 noescape: 1217 if (ch == 'Z' - 64) 1218 snprintf(b, sizeof b, "^Z"); 1219 else 1220 snprintf(b, sizeof b, "%c", ch); 1221 if ((r = sshbuf_putf(berr, 1222 "%c%s escape not available to " 1223 "multiplexed sessions\r\n", 1224 efc->escape_char, b)) != 0) 1225 fatal_fr(r, "sshbuf_putf"); 1226 continue; 1227 } 1228 /* Suspend the program. Inform the user */ 1229 if ((r = sshbuf_putf(berr, 1230 "%c^Z [suspend ssh]\r\n", 1231 efc->escape_char)) != 0) 1232 fatal_fr(r, "sshbuf_putf"); 1233 1234 /* Restore terminal modes and suspend. */ 1235 client_suspend_self(bin, bout, berr); 1236 1237 /* We have been continued. */ 1238 continue; 1239 1240 case 'B': 1241 if ((r = sshbuf_putf(berr, 1242 "%cB\r\n", efc->escape_char)) != 0) 1243 fatal_fr(r, "sshbuf_putf"); 1244 channel_request_start(ssh, c->self, "break", 0); 1245 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 || 1246 (r = sshpkt_send(ssh)) != 0) 1247 fatal_fr(r, "send packet"); 1248 continue; 1249 1250 case 'R': 1251 if (ssh->compat & SSH_BUG_NOREKEY) 1252 logit("Server does not " 1253 "support re-keying"); 1254 else 1255 need_rekeying = 1; 1256 continue; 1257 1258 case 'V': 1259 /* FALLTHROUGH */ 1260 case 'v': 1261 if (c && c->ctl_chan != -1) 1262 goto noescape; 1263 if (!log_is_on_stderr()) { 1264 if ((r = sshbuf_putf(berr, 1265 "%c%c [Logging to syslog]\r\n", 1266 efc->escape_char, ch)) != 0) 1267 fatal_fr(r, "sshbuf_putf"); 1268 continue; 1269 } 1270 if (ch == 'V' && options.log_level > 1271 SYSLOG_LEVEL_QUIET) 1272 log_change_level(--options.log_level); 1273 if (ch == 'v' && options.log_level < 1274 SYSLOG_LEVEL_DEBUG3) 1275 log_change_level(++options.log_level); 1276 if ((r = sshbuf_putf(berr, 1277 "%c%c [LogLevel %s]\r\n", 1278 efc->escape_char, ch, 1279 log_level_name(options.log_level))) != 0) 1280 fatal_fr(r, "sshbuf_putf"); 1281 continue; 1282 1283 case '&': 1284 if (c->ctl_chan != -1) 1285 goto noescape; 1286 /* 1287 * Detach the program (continue to serve 1288 * connections, but put in background and no 1289 * more new connections). 1290 */ 1291 /* Restore tty modes. */ 1292 leave_raw_mode( 1293 options.request_tty == REQUEST_TTY_FORCE); 1294 1295 /* Stop listening for new connections. */ 1296 channel_stop_listening(ssh); 1297 1298 if ((r = sshbuf_putf(berr, "%c& " 1299 "[backgrounded]\n", efc->escape_char)) != 0) 1300 fatal_fr(r, "sshbuf_putf"); 1301 1302 /* Fork into background. */ 1303 pid = fork(); 1304 if (pid == -1) { 1305 error("fork: %.100s", strerror(errno)); 1306 continue; 1307 } 1308 if (pid != 0) { /* This is the parent. */ 1309 /* The parent just exits. */ 1310 exit(0); 1311 } 1312 /* The child continues serving connections. */ 1313 /* fake EOF on stdin */ 1314 if ((r = sshbuf_put_u8(bin, 4)) != 0) 1315 fatal_fr(r, "sshbuf_put_u8"); 1316 return -1; 1317 case '?': 1318 print_escape_help(berr, efc->escape_char, 1319 (c && c->ctl_chan != -1), 1320 log_is_on_stderr()); 1321 continue; 1322 1323 case '#': 1324 if ((r = sshbuf_putf(berr, "%c#\r\n", 1325 efc->escape_char)) != 0) 1326 fatal_fr(r, "sshbuf_putf"); 1327 s = channel_open_message(ssh); 1328 if ((r = sshbuf_put(berr, s, strlen(s))) != 0) 1329 fatal_fr(r, "sshbuf_put"); 1330 free(s); 1331 continue; 1332 1333 case 'C': 1334 if (c && c->ctl_chan != -1) 1335 goto noescape; 1336 if (options.enable_escape_commandline == 0) { 1337 if ((r = sshbuf_putf(berr, 1338 "commandline disabled\r\n")) != 0) 1339 fatal_fr(r, "sshbuf_putf"); 1340 continue; 1341 } 1342 process_cmdline(ssh); 1343 continue; 1344 1345 default: 1346 if (ch != efc->escape_char) { 1347 if ((r = sshbuf_put_u8(bin, 1348 efc->escape_char)) != 0) 1349 fatal_fr(r, "sshbuf_put_u8"); 1350 bytes++; 1351 } 1352 /* Escaped characters fall through here */ 1353 break; 1354 } 1355 } else { 1356 /* 1357 * The previous character was not an escape char. 1358 * Check if this is an escape. 1359 */ 1360 if (last_was_cr && ch == efc->escape_char) { 1361 /* 1362 * It is. Set the flag and continue to 1363 * next character. 1364 */ 1365 efc->escape_pending = 1; 1366 continue; 1367 } 1368 } 1369 1370 /* 1371 * Normal character. Record whether it was a newline, 1372 * and append it to the buffer. 1373 */ 1374 last_was_cr = (ch == '\r' || ch == '\n'); 1375 if ((r = sshbuf_put_u8(bin, ch)) != 0) 1376 fatal_fr(r, "sshbuf_put_u8"); 1377 bytes++; 1378 } 1379 return bytes; 1380 } 1381 1382 /* 1383 * Get packets from the connection input buffer, and process them as long as 1384 * there are packets available. 1385 * 1386 * Any unknown packets received during the actual 1387 * session cause the session to terminate. This is 1388 * intended to make debugging easier since no 1389 * confirmations are sent. Any compatible protocol 1390 * extensions must be negotiated during the 1391 * preparatory phase. 1392 */ 1393 1394 static void 1395 client_process_buffered_input_packets(struct ssh *ssh) 1396 { 1397 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending); 1398 } 1399 1400 /* scan buf[] for '~' before sending data to the peer */ 1401 1402 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ 1403 void * 1404 client_new_escape_filter_ctx(int escape_char) 1405 { 1406 struct escape_filter_ctx *ret; 1407 1408 ret = xcalloc(1, sizeof(*ret)); 1409 ret->escape_pending = 0; 1410 ret->escape_char = escape_char; 1411 return (void *)ret; 1412 } 1413 1414 /* Free the escape filter context on channel free */ 1415 void 1416 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) 1417 { 1418 free(ctx); 1419 } 1420 1421 int 1422 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len) 1423 { 1424 if (c->extended_usage != CHAN_EXTENDED_WRITE) 1425 return 0; 1426 1427 return process_escapes(ssh, c, c->input, c->output, c->extended, 1428 buf, len); 1429 } 1430 1431 static void 1432 client_channel_closed(struct ssh *ssh, int id, int force, void *arg) 1433 { 1434 channel_cancel_cleanup(ssh, id); 1435 session_closed = 1; 1436 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1437 } 1438 1439 /* 1440 * Implements the interactive session with the server. This is called after 1441 * the user has been authenticated, and a command has been started on the 1442 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character 1443 * used as an escape character for terminating or suspending the session. 1444 */ 1445 int 1446 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, 1447 int ssh2_chan_id) 1448 { 1449 struct pollfd *pfd = NULL; 1450 u_int npfd_alloc = 0, npfd_active = 0; 1451 double start_time, total_time; 1452 int interactive = -1, channel_did_enqueue = 0, r; 1453 u_int64_t ibytes, obytes; 1454 int conn_in_ready, conn_out_ready; 1455 sigset_t bsigset, osigset; 1456 1457 debug("Entering interactive session."); 1458 session_ident = ssh2_chan_id; 1459 1460 if (options.control_master && 1461 !option_clear_or_none(options.control_path)) { 1462 debug("pledge: id"); 1463 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty", 1464 NULL) == -1) 1465 fatal_f("pledge(): %s", strerror(errno)); 1466 1467 } else if (options.forward_x11 || options.permit_local_command) { 1468 debug("pledge: exec"); 1469 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty", 1470 NULL) == -1) 1471 fatal_f("pledge(): %s", strerror(errno)); 1472 1473 } else if (options.update_hostkeys) { 1474 debug("pledge: filesystem"); 1475 if (pledge("stdio rpath wpath cpath unix inet dns proc tty", 1476 NULL) == -1) 1477 fatal_f("pledge(): %s", strerror(errno)); 1478 1479 } else if (!option_clear_or_none(options.proxy_command) || 1480 options.fork_after_authentication) { 1481 debug("pledge: proc"); 1482 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1) 1483 fatal_f("pledge(): %s", strerror(errno)); 1484 1485 } else { 1486 debug("pledge: network"); 1487 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 1488 fatal_f("pledge(): %s", strerror(errno)); 1489 } 1490 1491 /* might be able to tighten now */ 1492 client_repledge(); 1493 1494 start_time = monotime_double(); 1495 1496 /* Initialize variables. */ 1497 last_was_cr = 1; 1498 exit_status = -1; 1499 connection_in = ssh_packet_get_connection_in(ssh); 1500 connection_out = ssh_packet_get_connection_out(ssh); 1501 1502 quit_pending = 0; 1503 1504 client_init_dispatch(ssh); 1505 1506 /* 1507 * Set signal handlers, (e.g. to restore non-blocking mode) 1508 * but don't overwrite SIG_IGN, matches behaviour from rsh(1) 1509 */ 1510 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN) 1511 ssh_signal(SIGHUP, signal_handler); 1512 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN) 1513 ssh_signal(SIGINT, signal_handler); 1514 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN) 1515 ssh_signal(SIGQUIT, signal_handler); 1516 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN) 1517 ssh_signal(SIGTERM, signal_handler); 1518 ssh_signal(SIGWINCH, window_change_handler); 1519 #ifdef SIGINFO 1520 ssh_signal(SIGINFO, siginfo_handler); 1521 #endif 1522 1523 if (have_pty) 1524 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1525 1526 if (session_ident != -1) { 1527 if (escape_char_arg != SSH_ESCAPECHAR_NONE) { 1528 channel_register_filter(ssh, session_ident, 1529 client_simple_escape_filter, NULL, 1530 client_filter_cleanup, 1531 client_new_escape_filter_ctx( 1532 escape_char_arg)); 1533 } 1534 channel_register_cleanup(ssh, session_ident, 1535 client_channel_closed, 0); 1536 } 1537 1538 schedule_server_alive_check(); 1539 1540 if (sigemptyset(&bsigset) == -1 || 1541 sigaddset(&bsigset, SIGHUP) == -1 || 1542 sigaddset(&bsigset, SIGINT) == -1 || 1543 sigaddset(&bsigset, SIGQUIT) == -1 || 1544 sigaddset(&bsigset, SIGTERM) == -1) 1545 error_f("bsigset setup: %s", strerror(errno)); 1546 #ifdef SIGINFO 1547 if (sigaddset(&bsigset, SIGINFO) == -1) 1548 error_f("bsigset setup: %s", strerror(errno)); 1549 #endif 1550 1551 /* Main loop of the client for the interactive session mode. */ 1552 while (!quit_pending) { 1553 channel_did_enqueue = 0; 1554 1555 /* Process buffered packets sent by the server. */ 1556 client_process_buffered_input_packets(ssh); 1557 1558 if (session_closed && !channel_still_open(ssh)) 1559 break; 1560 1561 if (ssh_packet_is_rekeying(ssh)) { 1562 debug("rekeying in progress"); 1563 } else if (need_rekeying) { 1564 /* manual rekey request */ 1565 debug("need rekeying"); 1566 if ((r = kex_start_rekex(ssh)) != 0) 1567 fatal_fr(r, "kex_start_rekex"); 1568 need_rekeying = 0; 1569 } else { 1570 /* 1571 * Make packets from buffered channel data, and 1572 * enqueue them for sending to the server. 1573 */ 1574 if (ssh_packet_not_very_much_data_to_write(ssh)) 1575 channel_did_enqueue = channel_output_poll(ssh); 1576 1577 /* 1578 * Check if the window size has changed, and buffer a 1579 * message about it to the server if so. 1580 */ 1581 client_check_window_change(ssh); 1582 } 1583 /* 1584 * Wait until we have something to do (something becomes 1585 * available on one of the descriptors). 1586 */ 1587 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1) 1588 error_f("bsigset sigprocmask: %s", strerror(errno)); 1589 if (siginfo_received) { 1590 siginfo_received = 0; 1591 channel_report_open(ssh, SYSLOG_LEVEL_INFO); 1592 } 1593 if (quit_pending) 1594 break; 1595 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc, 1596 &npfd_active, channel_did_enqueue, &osigset, 1597 &conn_in_ready, &conn_out_ready); 1598 if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1) 1599 error_f("osigset sigprocmask: %s", strerror(errno)); 1600 1601 if (quit_pending) 1602 break; 1603 1604 /* Do channel operations. */ 1605 channel_after_poll(ssh, pfd, npfd_active); 1606 1607 /* Buffer input from the connection. */ 1608 if (conn_in_ready) 1609 client_process_net_input(ssh); 1610 1611 if (quit_pending) 1612 break; 1613 1614 /* A timeout may have triggered rekeying */ 1615 if ((r = ssh_packet_check_rekey(ssh)) != 0) 1616 fatal_fr(r, "cannot start rekeying"); 1617 1618 /* 1619 * Send as much buffered packet data as possible to the 1620 * sender. 1621 */ 1622 if (conn_out_ready) { 1623 if (interactive != !channel_has_bulk(ssh)) { 1624 interactive = !channel_has_bulk(ssh); 1625 debug2_f("session QoS is now %s", interactive ? 1626 "interactive" : "non-interactive"); 1627 ssh_packet_set_interactive(ssh, interactive); 1628 } 1629 if ((r = ssh_packet_write_poll(ssh)) != 0) { 1630 sshpkt_fatal(ssh, r, 1631 "%s: ssh_packet_write_poll", __func__); 1632 } 1633 } 1634 1635 /* 1636 * If we are a backgrounded control master, and the 1637 * timeout has expired without any active client 1638 * connections, then quit. 1639 */ 1640 if (control_persist_exit_time > 0) { 1641 if (monotime() >= control_persist_exit_time) { 1642 debug("ControlPersist timeout expired"); 1643 break; 1644 } 1645 } 1646 } 1647 free(pfd); 1648 1649 /* Terminate the session. */ 1650 1651 /* 1652 * In interactive mode (with pseudo tty) display a message indicating 1653 * that the connection has been closed. 1654 */ 1655 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO) 1656 quit_message("Connection to %s closed.", host); 1657 1658 1659 /* Stop watching for window change. */ 1660 ssh_signal(SIGWINCH, SIG_DFL); 1661 1662 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || 1663 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 || 1664 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 || 1665 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */ 1666 (r = sshpkt_send(ssh)) != 0 || 1667 (r = ssh_packet_write_wait(ssh)) != 0) 1668 fatal_fr(r, "send disconnect"); 1669 1670 channel_free_all(ssh); 1671 1672 if (have_pty) 1673 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1674 1675 /* 1676 * If there was no shell or command requested, there will be no remote 1677 * exit status to be returned. In that case, clear error code if the 1678 * connection was deliberately terminated at this end. 1679 */ 1680 if (options.session_type == SESSION_TYPE_NONE && 1681 received_signal == SIGTERM) { 1682 received_signal = 0; 1683 exit_status = 0; 1684 } 1685 1686 if (received_signal) { 1687 verbose("Killed by signal %d.", (int) received_signal); 1688 cleanup_exit(255); 1689 } 1690 1691 /* Report bytes transferred, and transfer rates. */ 1692 total_time = monotime_double() - start_time; 1693 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1694 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", 1695 (unsigned long long)obytes, (unsigned long long)ibytes, total_time); 1696 if (total_time > 0) 1697 verbose("Bytes per second: sent %.1f, received %.1f", 1698 obytes / total_time, ibytes / total_time); 1699 /* Return the exit status of the program. */ 1700 debug("Exit status %d", exit_status); 1701 return exit_status; 1702 } 1703 1704 /*********/ 1705 1706 static Channel * 1707 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, 1708 int rchan, u_int rwindow, u_int rmaxpack) 1709 { 1710 Channel *c = NULL; 1711 struct sshbuf *b = NULL; 1712 char *listen_address, *originator_address; 1713 u_int listen_port, originator_port; 1714 int r; 1715 1716 /* Get rest of the packet */ 1717 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 || 1718 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 || 1719 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 || 1720 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1721 (r = sshpkt_get_end(ssh)) != 0) 1722 fatal_fr(r, "parse packet"); 1723 1724 debug_f("listen %s port %d, originator %s port %d", 1725 listen_address, listen_port, originator_address, originator_port); 1726 1727 if (listen_port > 0xffff) 1728 error_f("invalid listen port"); 1729 else if (originator_port > 0xffff) 1730 error_f("invalid originator port"); 1731 else { 1732 c = channel_connect_by_listen_address(ssh, 1733 listen_address, listen_port, "forwarded-tcpip", 1734 originator_address); 1735 } 1736 1737 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1738 if ((b = sshbuf_new()) == NULL) { 1739 error_f("alloc reply"); 1740 goto out; 1741 } 1742 /* reconstruct and send to muxclient */ 1743 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ 1744 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1745 (r = sshbuf_put_cstring(b, request_type)) != 0 || 1746 (r = sshbuf_put_u32(b, rchan)) != 0 || 1747 (r = sshbuf_put_u32(b, rwindow)) != 0 || 1748 (r = sshbuf_put_u32(b, rmaxpack)) != 0 || 1749 (r = sshbuf_put_cstring(b, listen_address)) != 0 || 1750 (r = sshbuf_put_u32(b, listen_port)) != 0 || 1751 (r = sshbuf_put_cstring(b, originator_address)) != 0 || 1752 (r = sshbuf_put_u32(b, originator_port)) != 0 || 1753 (r = sshbuf_put_stringb(c->output, b)) != 0) { 1754 error_fr(r, "compose for muxclient"); 1755 goto out; 1756 } 1757 } 1758 1759 out: 1760 sshbuf_free(b); 1761 free(originator_address); 1762 free(listen_address); 1763 return c; 1764 } 1765 1766 static Channel * 1767 client_request_forwarded_streamlocal(struct ssh *ssh, 1768 const char *request_type, int rchan) 1769 { 1770 Channel *c = NULL; 1771 char *listen_path; 1772 int r; 1773 1774 /* Get the remote path. */ 1775 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 || 1776 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */ 1777 (r = sshpkt_get_end(ssh)) != 0) 1778 fatal_fr(r, "parse packet"); 1779 1780 debug_f("request: %s", listen_path); 1781 1782 c = channel_connect_by_listen_path(ssh, listen_path, 1783 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); 1784 free(listen_path); 1785 return c; 1786 } 1787 1788 static Channel * 1789 client_request_x11(struct ssh *ssh, const char *request_type, int rchan) 1790 { 1791 Channel *c = NULL; 1792 char *originator; 1793 u_int originator_port; 1794 int r, sock; 1795 1796 if (!options.forward_x11) { 1797 error("Warning: ssh server tried X11 forwarding."); 1798 error("Warning: this is probably a break-in attempt by a " 1799 "malicious server."); 1800 return NULL; 1801 } 1802 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) { 1803 verbose("Rejected X11 connection after ForwardX11Timeout " 1804 "expired"); 1805 return NULL; 1806 } 1807 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 1808 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1809 (r = sshpkt_get_end(ssh)) != 0) 1810 fatal_fr(r, "parse packet"); 1811 /* XXX check permission */ 1812 /* XXX range check originator port? */ 1813 debug("client_request_x11: request from %s %u", originator, 1814 originator_port); 1815 free(originator); 1816 sock = x11_connect_display(ssh); 1817 if (sock < 0) 1818 return NULL; 1819 c = channel_new(ssh, "x11-connection", 1820 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1821 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1822 c->force_drain = 1; 1823 return c; 1824 } 1825 1826 static Channel * 1827 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1828 { 1829 Channel *c = NULL; 1830 int r, sock; 1831 1832 if (!options.forward_agent) { 1833 error("Warning: ssh server tried agent forwarding."); 1834 error("Warning: this is probably a break-in attempt by a " 1835 "malicious server."); 1836 return NULL; 1837 } 1838 if (forward_agent_sock_path == NULL) { 1839 r = ssh_get_authentication_socket(&sock); 1840 } else { 1841 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1842 } 1843 if (r != 0) { 1844 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1845 debug_fr(r, "ssh_get_authentication_socket"); 1846 return NULL; 1847 } 1848 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1849 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1850 debug_f("bound agent to hostkey"); 1851 else 1852 debug2_fr(r, "ssh_agent_bind_hostkey"); 1853 1854 c = channel_new(ssh, "agent-connection", 1855 SSH_CHANNEL_OPEN, sock, sock, -1, 1856 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1857 "authentication agent connection", 1); 1858 c->force_drain = 1; 1859 return c; 1860 } 1861 1862 char * 1863 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1864 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1865 { 1866 Channel *c; 1867 int r, fd; 1868 char *ifname = NULL; 1869 1870 if (tun_mode == SSH_TUNMODE_NO) 1871 return NULL; 1872 1873 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1874 1875 /* Open local tunnel device */ 1876 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1877 error("Tunnel device open failed."); 1878 return NULL; 1879 } 1880 debug("Tunnel forwarding using interface %s", ifname); 1881 1882 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1883 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1884 c->datagram = 1; 1885 1886 #if defined(SSH_TUN_FILTER) 1887 if (options.tun_open == SSH_TUNMODE_POINTOPOINT) 1888 channel_register_filter(ssh, c->self, sys_tun_infilter, 1889 sys_tun_outfilter, NULL, NULL); 1890 #endif 1891 1892 if (cb != NULL) 1893 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1894 1895 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1896 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1897 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1898 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1899 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1900 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1901 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1902 (r = sshpkt_send(ssh)) != 0) 1903 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1904 1905 return ifname; 1906 } 1907 1908 /* XXXX move to generic input handler */ 1909 static int 1910 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1911 { 1912 Channel *c = NULL; 1913 char *ctype = NULL; 1914 int r; 1915 u_int rchan; 1916 size_t len; 1917 u_int rmaxpack, rwindow; 1918 1919 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1920 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1921 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1922 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1923 goto out; 1924 1925 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1926 ctype, rchan, rwindow, rmaxpack); 1927 1928 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1929 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1930 rmaxpack); 1931 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1932 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1933 } else if (strcmp(ctype, "x11") == 0) { 1934 c = client_request_x11(ssh, ctype, rchan); 1935 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1936 c = client_request_agent(ssh, ctype, rchan); 1937 } 1938 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1939 debug3("proxied to downstream: %s", ctype); 1940 } else if (c != NULL) { 1941 debug("confirm %s", ctype); 1942 c->remote_id = rchan; 1943 c->have_remote_id = 1; 1944 c->remote_window = rwindow; 1945 c->remote_maxpacket = rmaxpack; 1946 if (c->type != SSH_CHANNEL_CONNECTING) { 1947 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1948 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1949 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1950 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1951 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1952 (r = sshpkt_send(ssh)) != 0) 1953 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1954 } 1955 } else { 1956 debug("failure %s", ctype); 1957 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1958 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1959 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1960 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1961 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1962 (r = sshpkt_send(ssh)) != 0) 1963 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1964 } 1965 r = 0; 1966 out: 1967 free(ctype); 1968 return r; 1969 } 1970 1971 static int 1972 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1973 { 1974 Channel *c = NULL; 1975 char *rtype = NULL; 1976 u_char reply; 1977 u_int id, exitval; 1978 int r, success = 0; 1979 1980 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1981 return r; 1982 if (id <= INT_MAX) 1983 c = channel_lookup(ssh, id); 1984 if (channel_proxy_upstream(c, type, seq, ssh)) 1985 return 0; 1986 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1987 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1988 goto out; 1989 1990 debug("client_input_channel_req: channel %u rtype %s reply %d", 1991 id, rtype, reply); 1992 1993 if (c == NULL) { 1994 error("client_input_channel_req: channel %d: " 1995 "unknown channel", id); 1996 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 1997 if ((r = sshpkt_get_end(ssh)) != 0) 1998 goto out; 1999 chan_rcvd_eow(ssh, c); 2000 } else if (strcmp(rtype, "exit-status") == 0) { 2001 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 2002 goto out; 2003 if (c->ctl_chan != -1) { 2004 mux_exit_message(ssh, c, exitval); 2005 success = 1; 2006 } else if ((int)id == session_ident) { 2007 /* Record exit value of local session */ 2008 success = 1; 2009 exit_status = exitval; 2010 } else { 2011 /* Probably for a mux channel that has already closed */ 2012 debug_f("no sink for exit-status on channel %d", 2013 id); 2014 } 2015 if ((r = sshpkt_get_end(ssh)) != 0) 2016 goto out; 2017 } 2018 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 2019 if (!c->have_remote_id) 2020 fatal_f("channel %d: no remote_id", c->self); 2021 if ((r = sshpkt_start(ssh, success ? 2022 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2023 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2024 (r = sshpkt_send(ssh)) != 0) 2025 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2026 } 2027 r = 0; 2028 out: 2029 free(rtype); 2030 return r; 2031 } 2032 2033 struct hostkeys_update_ctx { 2034 /* The hostname and (optionally) IP address string for the server */ 2035 char *host_str, *ip_str; 2036 2037 /* 2038 * Keys received from the server and a flag for each indicating 2039 * whether they already exist in known_hosts. 2040 * keys_match is filled in by hostkeys_find() and later (for new 2041 * keys) by client_global_hostkeys_prove_confirm(). 2042 */ 2043 struct sshkey **keys; 2044 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2045 int *keys_verified; /* flag for new keys verified by server */ 2046 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2047 2048 /* 2049 * Keys that are in known_hosts, but were not present in the update 2050 * from the server (i.e. scheduled to be deleted). 2051 * Filled in by hostkeys_find(). 2052 */ 2053 struct sshkey **old_keys; 2054 size_t nold; 2055 2056 /* Various special cases. */ 2057 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2058 int ca_available; /* saw CA key for this host */ 2059 int old_key_seen; /* saw old key with other name/addr */ 2060 int other_name_seen; /* saw key with other name/addr */ 2061 }; 2062 2063 static void 2064 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2065 { 2066 size_t i; 2067 2068 if (ctx == NULL) 2069 return; 2070 for (i = 0; i < ctx->nkeys; i++) 2071 sshkey_free(ctx->keys[i]); 2072 free(ctx->keys); 2073 free(ctx->keys_match); 2074 free(ctx->keys_verified); 2075 for (i = 0; i < ctx->nold; i++) 2076 sshkey_free(ctx->old_keys[i]); 2077 free(ctx->old_keys); 2078 free(ctx->host_str); 2079 free(ctx->ip_str); 2080 free(ctx); 2081 } 2082 2083 /* 2084 * Returns non-zero if a known_hosts hostname list is not of a form that 2085 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2086 * hostnames lists that do not follow the form host[,ip]. 2087 */ 2088 static int 2089 hostspec_is_complex(const char *hosts) 2090 { 2091 char *cp; 2092 2093 /* wildcard */ 2094 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2095 return 1; 2096 /* single host/ip = ok */ 2097 if ((cp = strchr(hosts, ',')) == NULL) 2098 return 0; 2099 /* more than two entries on the line */ 2100 if (strchr(cp + 1, ',') != NULL) 2101 return 1; 2102 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2103 return 0; 2104 } 2105 2106 /* callback to search for ctx->keys in known_hosts */ 2107 static int 2108 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2109 { 2110 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2111 size_t i; 2112 struct sshkey **tmp; 2113 2114 if (l->key == NULL) 2115 return 0; 2116 if (l->status != HKF_STATUS_MATCHED) { 2117 /* Record if one of the keys appears on a non-matching line */ 2118 for (i = 0; i < ctx->nkeys; i++) { 2119 if (sshkey_equal(l->key, ctx->keys[i])) { 2120 ctx->other_name_seen = 1; 2121 debug3_f("found %s key under different " 2122 "name/addr at %s:%ld", 2123 sshkey_ssh_name(ctx->keys[i]), 2124 l->path, l->linenum); 2125 return 0; 2126 } 2127 } 2128 return 0; 2129 } 2130 /* Don't proceed if revocation or CA markers are present */ 2131 /* XXX relax this */ 2132 if (l->marker != MRK_NONE) { 2133 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2134 l->path, l->linenum); 2135 ctx->complex_hostspec = 1; 2136 return 0; 2137 } 2138 2139 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2140 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2141 if ((l->match & HKF_MATCH_HOST) == 0) { 2142 /* Record if address matched a different hostname. */ 2143 ctx->other_name_seen = 1; 2144 debug3_f("found address %s against different hostname " 2145 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2146 return 0; 2147 } else if ((l->match & HKF_MATCH_IP) == 0) { 2148 /* Record if hostname matched a different address. */ 2149 ctx->other_name_seen = 1; 2150 debug3_f("found hostname %s against different address " 2151 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2152 } 2153 } 2154 2155 /* 2156 * UpdateHostkeys is skipped for wildcard host names and hostnames 2157 * that contain more than two entries (ssh never writes these). 2158 */ 2159 if (hostspec_is_complex(l->hosts)) { 2160 debug3_f("hostkeys file %s:%ld complex host specification", 2161 l->path, l->linenum); 2162 ctx->complex_hostspec = 1; 2163 return 0; 2164 } 2165 2166 /* Mark off keys we've already seen for this host */ 2167 for (i = 0; i < ctx->nkeys; i++) { 2168 if (!sshkey_equal(l->key, ctx->keys[i])) 2169 continue; 2170 debug3_f("found %s key at %s:%ld", 2171 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2172 ctx->keys_match[i] |= l->match; 2173 return 0; 2174 } 2175 /* This line contained a key that not offered by the server */ 2176 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2177 l->path, l->linenum); 2178 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2179 sizeof(*ctx->old_keys))) == NULL) 2180 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2181 ctx->old_keys = tmp; 2182 ctx->old_keys[ctx->nold++] = l->key; 2183 l->key = NULL; 2184 2185 return 0; 2186 } 2187 2188 /* callback to search for ctx->old_keys in known_hosts under other names */ 2189 static int 2190 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2191 { 2192 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2193 size_t i; 2194 int hashed; 2195 2196 /* only care about lines that *don't* match the active host spec */ 2197 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2198 return 0; 2199 2200 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2201 for (i = 0; i < ctx->nold; i++) { 2202 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2203 continue; 2204 debug3_f("found deprecated %s key at %s:%ld as %s", 2205 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2206 hashed ? "[HASHED]" : l->hosts); 2207 ctx->old_key_seen = 1; 2208 break; 2209 } 2210 return 0; 2211 } 2212 2213 /* 2214 * Check known_hosts files for deprecated keys under other names. Returns 0 2215 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2216 * exist under names other than the active hostname/IP. 2217 */ 2218 static int 2219 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2220 { 2221 size_t i; 2222 int r; 2223 2224 debug2_f("checking for %zu deprecated keys", ctx->nold); 2225 for (i = 0; i < options.num_user_hostfiles; i++) { 2226 debug3_f("searching %s for %s / %s", 2227 options.user_hostfiles[i], ctx->host_str, 2228 ctx->ip_str ? ctx->ip_str : "(none)"); 2229 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2230 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2231 HKF_WANT_PARSE_KEY, 0)) != 0) { 2232 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2233 debug_f("hostkeys file %s does not exist", 2234 options.user_hostfiles[i]); 2235 continue; 2236 } 2237 error_fr(r, "hostkeys_foreach failed for %s", 2238 options.user_hostfiles[i]); 2239 return -1; 2240 } 2241 } 2242 return 0; 2243 } 2244 2245 static void 2246 hostkey_change_preamble(LogLevel loglevel) 2247 { 2248 do_log2(loglevel, "The server has updated its host keys."); 2249 do_log2(loglevel, "These changes were verified by the server's " 2250 "existing trusted key."); 2251 } 2252 2253 static void 2254 update_known_hosts(struct hostkeys_update_ctx *ctx) 2255 { 2256 int r, was_raw = 0, first = 1; 2257 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2258 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2259 char *fp, *response; 2260 size_t i; 2261 struct stat sb; 2262 2263 for (i = 0; i < ctx->nkeys; i++) { 2264 if (!ctx->keys_verified[i]) 2265 continue; 2266 if ((fp = sshkey_fingerprint(ctx->keys[i], 2267 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2268 fatal_f("sshkey_fingerprint failed"); 2269 if (first && asking) 2270 hostkey_change_preamble(loglevel); 2271 do_log2(loglevel, "Learned new hostkey: %s %s", 2272 sshkey_type(ctx->keys[i]), fp); 2273 first = 0; 2274 free(fp); 2275 } 2276 for (i = 0; i < ctx->nold; i++) { 2277 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2278 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2279 fatal_f("sshkey_fingerprint failed"); 2280 if (first && asking) 2281 hostkey_change_preamble(loglevel); 2282 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2283 sshkey_type(ctx->old_keys[i]), fp); 2284 first = 0; 2285 free(fp); 2286 } 2287 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2288 if (get_saved_tio() != NULL) { 2289 leave_raw_mode(1); 2290 was_raw = 1; 2291 } 2292 response = NULL; 2293 for (i = 0; !quit_pending && i < 3; i++) { 2294 free(response); 2295 response = read_passphrase("Accept updated hostkeys? " 2296 "(yes/no): ", RP_ECHO); 2297 if (response != NULL && strcasecmp(response, "yes") == 0) 2298 break; 2299 else if (quit_pending || response == NULL || 2300 strcasecmp(response, "no") == 0) { 2301 options.update_hostkeys = 0; 2302 break; 2303 } else { 2304 do_log2(loglevel, "Please enter " 2305 "\"yes\" or \"no\""); 2306 } 2307 } 2308 if (quit_pending || i >= 3 || response == NULL) 2309 options.update_hostkeys = 0; 2310 free(response); 2311 if (was_raw) 2312 enter_raw_mode(1); 2313 } 2314 if (options.update_hostkeys == 0) 2315 return; 2316 /* 2317 * Now that all the keys are verified, we can go ahead and replace 2318 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2319 * cancel the operation). 2320 */ 2321 for (i = 0; i < options.num_user_hostfiles; i++) { 2322 /* 2323 * NB. keys are only added to hostfiles[0], for the rest we 2324 * just delete the hostname entries. 2325 */ 2326 if (stat(options.user_hostfiles[i], &sb) != 0) { 2327 if (errno == ENOENT) { 2328 debug_f("known hosts file %s does not " 2329 "exist", options.user_hostfiles[i]); 2330 } else { 2331 error_f("known hosts file %s " 2332 "inaccessible: %s", 2333 options.user_hostfiles[i], strerror(errno)); 2334 } 2335 continue; 2336 } 2337 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2338 ctx->host_str, ctx->ip_str, 2339 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2340 options.hash_known_hosts, 0, 2341 options.fingerprint_hash)) != 0) { 2342 error_fr(r, "hostfile_replace_entries failed for %s", 2343 options.user_hostfiles[i]); 2344 } 2345 } 2346 } 2347 2348 static void 2349 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2350 u_int32_t seq, void *_ctx) 2351 { 2352 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2353 size_t i, ndone; 2354 struct sshbuf *signdata; 2355 int r, plaintype; 2356 const u_char *sig; 2357 const char *rsa_kexalg = NULL; 2358 char *alg = NULL; 2359 size_t siglen; 2360 2361 if (ctx->nnew == 0) 2362 fatal_f("ctx->nnew == 0"); /* sanity */ 2363 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2364 error("Server failed to confirm ownership of " 2365 "private host keys"); 2366 hostkeys_update_ctx_free(ctx); 2367 return; 2368 } 2369 if (sshkey_type_plain(sshkey_type_from_name( 2370 ssh->kex->hostkey_alg)) == KEY_RSA) 2371 rsa_kexalg = ssh->kex->hostkey_alg; 2372 if ((signdata = sshbuf_new()) == NULL) 2373 fatal_f("sshbuf_new failed"); 2374 /* 2375 * Expect a signature for each of the ctx->nnew private keys we 2376 * haven't seen before. They will be in the same order as the 2377 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2378 */ 2379 for (ndone = i = 0; i < ctx->nkeys; i++) { 2380 if (ctx->keys_match[i]) 2381 continue; 2382 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2383 /* Prepare data to be signed: session ID, unique string, key */ 2384 sshbuf_reset(signdata); 2385 if ( (r = sshbuf_put_cstring(signdata, 2386 "hostkeys-prove-00@openssh.com")) != 0 || 2387 (r = sshbuf_put_stringb(signdata, 2388 ssh->kex->session_id)) != 0 || 2389 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2390 fatal_fr(r, "compose signdata"); 2391 /* Extract and verify signature */ 2392 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2393 error_fr(r, "parse sig"); 2394 goto out; 2395 } 2396 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2397 error_fr(r, "server gave unintelligible signature " 2398 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2399 goto out; 2400 } 2401 /* 2402 * Special case for RSA keys: if a RSA hostkey was negotiated, 2403 * then use its signature type for verification of RSA hostkey 2404 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2405 */ 2406 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2407 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2408 debug_f("server used untrusted RSA signature algorithm " 2409 "%s for key %zu, disregarding", alg, i); 2410 free(alg); 2411 /* zap the key from the list */ 2412 sshkey_free(ctx->keys[i]); 2413 ctx->keys[i] = NULL; 2414 ndone++; 2415 continue; 2416 } 2417 debug3_f("verify %s key %zu using sigalg %s", 2418 sshkey_type(ctx->keys[i]), i, alg); 2419 free(alg); 2420 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2421 sshbuf_ptr(signdata), sshbuf_len(signdata), 2422 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2423 error_fr(r, "server gave bad signature for %s key %zu", 2424 sshkey_type(ctx->keys[i]), i); 2425 goto out; 2426 } 2427 /* Key is good. Mark it as 'seen' */ 2428 ctx->keys_verified[i] = 1; 2429 ndone++; 2430 } 2431 /* Shouldn't happen */ 2432 if (ndone != ctx->nnew) 2433 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2434 if ((r = sshpkt_get_end(ssh)) != 0) { 2435 error_f("protocol error"); 2436 goto out; 2437 } 2438 2439 /* Make the edits to known_hosts */ 2440 update_known_hosts(ctx); 2441 out: 2442 sshbuf_free(signdata); 2443 hostkeys_update_ctx_free(ctx); 2444 hostkeys_update_complete = 1; 2445 client_repledge(); 2446 } 2447 2448 /* 2449 * Handle hostkeys-00@openssh.com global request to inform the client of all 2450 * the server's hostkeys. The keys are checked against the user's 2451 * HostkeyAlgorithms preference before they are accepted. 2452 */ 2453 static int 2454 client_input_hostkeys(struct ssh *ssh) 2455 { 2456 const u_char *blob = NULL; 2457 size_t i, len = 0; 2458 struct sshbuf *buf = NULL; 2459 struct sshkey *key = NULL, **tmp; 2460 int r, prove_sent = 0; 2461 char *fp; 2462 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2463 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2464 struct hostkeys_update_ctx *ctx = NULL; 2465 u_int want; 2466 2467 if (hostkeys_seen) 2468 fatal_f("server already sent hostkeys"); 2469 if (!can_update_hostkeys()) 2470 return 1; 2471 hostkeys_seen = 1; 2472 2473 ctx = xcalloc(1, sizeof(*ctx)); 2474 while (ssh_packet_remaining(ssh) > 0) { 2475 sshkey_free(key); 2476 key = NULL; 2477 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2478 error_fr(r, "parse key"); 2479 goto out; 2480 } 2481 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2482 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2483 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2484 "convert key"); 2485 continue; 2486 } 2487 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2488 SSH_FP_DEFAULT); 2489 debug3_f("received %s key %s", sshkey_type(key), fp); 2490 free(fp); 2491 2492 if (!hostkey_accepted_by_hostkeyalgs(key)) { 2493 debug3_f("%s key not permitted by " 2494 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2495 continue; 2496 } 2497 /* Skip certs */ 2498 if (sshkey_is_cert(key)) { 2499 debug3_f("%s key is a certificate; skipping", 2500 sshkey_ssh_name(key)); 2501 continue; 2502 } 2503 /* Ensure keys are unique */ 2504 for (i = 0; i < ctx->nkeys; i++) { 2505 if (sshkey_equal(key, ctx->keys[i])) { 2506 error_f("received duplicated %s host key", 2507 sshkey_ssh_name(key)); 2508 goto out; 2509 } 2510 } 2511 /* Key is good, record it */ 2512 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2513 sizeof(*ctx->keys))) == NULL) 2514 fatal_f("recallocarray failed nkeys = %zu", 2515 ctx->nkeys); 2516 ctx->keys = tmp; 2517 ctx->keys[ctx->nkeys++] = key; 2518 key = NULL; 2519 } 2520 2521 if (ctx->nkeys == 0) { 2522 debug_f("server sent no hostkeys"); 2523 goto out; 2524 } 2525 2526 if ((ctx->keys_match = calloc(ctx->nkeys, 2527 sizeof(*ctx->keys_match))) == NULL || 2528 (ctx->keys_verified = calloc(ctx->nkeys, 2529 sizeof(*ctx->keys_verified))) == NULL) 2530 fatal_f("calloc failed"); 2531 2532 get_hostfile_hostname_ipaddr(host, 2533 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2534 options.port, &ctx->host_str, 2535 options.check_host_ip ? &ctx->ip_str : NULL); 2536 2537 /* Find which keys we already know about. */ 2538 for (i = 0; i < options.num_user_hostfiles; i++) { 2539 debug_f("searching %s for %s / %s", 2540 options.user_hostfiles[i], ctx->host_str, 2541 ctx->ip_str ? ctx->ip_str : "(none)"); 2542 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2543 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2544 HKF_WANT_PARSE_KEY, 0)) != 0) { 2545 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2546 debug_f("hostkeys file %s does not exist", 2547 options.user_hostfiles[i]); 2548 continue; 2549 } 2550 error_fr(r, "hostkeys_foreach failed for %s", 2551 options.user_hostfiles[i]); 2552 goto out; 2553 } 2554 } 2555 2556 /* Figure out if we have any new keys to add */ 2557 ctx->nnew = ctx->nincomplete = 0; 2558 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2559 for (i = 0; i < ctx->nkeys; i++) { 2560 if (ctx->keys_match[i] == 0) 2561 ctx->nnew++; 2562 if ((ctx->keys_match[i] & want) != want) 2563 ctx->nincomplete++; 2564 } 2565 2566 debug3_f("%zu server keys: %zu new, %zu retained, " 2567 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2568 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2569 ctx->nincomplete, ctx->nold); 2570 2571 if (ctx->nnew == 0 && ctx->nold == 0) { 2572 debug_f("no new or deprecated keys from server"); 2573 goto out; 2574 } 2575 2576 /* Various reasons why we cannot proceed with the update */ 2577 if (ctx->complex_hostspec) { 2578 debug_f("CA/revocation marker, manual host list or wildcard " 2579 "host pattern found, skipping UserKnownHostsFile update"); 2580 goto out; 2581 } 2582 if (ctx->other_name_seen) { 2583 debug_f("host key found matching a different name/address, " 2584 "skipping UserKnownHostsFile update"); 2585 goto out; 2586 } 2587 /* 2588 * If removing keys, check whether they appear under different 2589 * names/addresses and refuse to proceed if they do. This avoids 2590 * cases such as hosts with multiple names becoming inconsistent 2591 * with regards to CheckHostIP entries. 2592 * XXX UpdateHostkeys=force to override this (and other) checks? 2593 */ 2594 if (ctx->nold != 0) { 2595 if (check_old_keys_othernames(ctx) != 0) 2596 goto out; /* error already logged */ 2597 if (ctx->old_key_seen) { 2598 debug_f("key(s) for %s%s%s exist under other names; " 2599 "skipping UserKnownHostsFile update", 2600 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2601 ctx->ip_str == NULL ? "" : ctx->ip_str); 2602 goto out; 2603 } 2604 } 2605 2606 if (ctx->nnew == 0) { 2607 /* 2608 * We have some keys to remove or fix matching for. 2609 * We can proceed to do this without requiring a fresh proof 2610 * from the server. 2611 */ 2612 update_known_hosts(ctx); 2613 goto out; 2614 } 2615 /* 2616 * We have received previously-unseen keys from the server. 2617 * Ask the server to confirm ownership of the private halves. 2618 */ 2619 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2620 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2621 (r = sshpkt_put_cstring(ssh, 2622 "hostkeys-prove-00@openssh.com")) != 0 || 2623 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2624 fatal_fr(r, "prepare hostkeys-prove"); 2625 if ((buf = sshbuf_new()) == NULL) 2626 fatal_f("sshbuf_new"); 2627 for (i = 0; i < ctx->nkeys; i++) { 2628 if (ctx->keys_match[i]) 2629 continue; 2630 sshbuf_reset(buf); 2631 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2632 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2633 fatal_fr(r, "assemble hostkeys-prove"); 2634 } 2635 if ((r = sshpkt_send(ssh)) != 0) 2636 fatal_fr(r, "send hostkeys-prove"); 2637 client_register_global_confirm( 2638 client_global_hostkeys_prove_confirm, ctx); 2639 ctx = NULL; /* will be freed in callback */ 2640 prove_sent = 1; 2641 2642 /* Success */ 2643 out: 2644 hostkeys_update_ctx_free(ctx); 2645 sshkey_free(key); 2646 sshbuf_free(buf); 2647 if (!prove_sent) { 2648 /* UpdateHostkeys handling completed */ 2649 hostkeys_update_complete = 1; 2650 client_repledge(); 2651 } 2652 /* 2653 * NB. Return success for all cases. The server doesn't need to know 2654 * what the client does with its hosts file. 2655 */ 2656 return 1; 2657 } 2658 2659 static int 2660 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2661 { 2662 char *rtype; 2663 u_char want_reply; 2664 int r, success = 0; 2665 2666 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2667 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2668 goto out; 2669 debug("client_input_global_request: rtype %s want_reply %d", 2670 rtype, want_reply); 2671 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2672 success = client_input_hostkeys(ssh); 2673 if (want_reply) { 2674 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2675 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2676 (r = sshpkt_send(ssh)) != 0 || 2677 (r = ssh_packet_write_wait(ssh)) != 0) 2678 goto out; 2679 } 2680 r = 0; 2681 out: 2682 free(rtype); 2683 return r; 2684 } 2685 2686 static void 2687 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2688 { 2689 int r; 2690 2691 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2692 channel_request_start(ssh, id, "env", 0); 2693 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2694 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2695 (r = sshpkt_send(ssh)) != 0) 2696 fatal_fr(r, "send setenv"); 2697 } 2698 2699 void 2700 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2701 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2702 char **env) 2703 { 2704 size_t i, j, len; 2705 int matched, r; 2706 char *name, *val; 2707 Channel *c = NULL; 2708 2709 debug2_f("id %d", id); 2710 2711 if ((c = channel_lookup(ssh, id)) == NULL) 2712 fatal_f("channel %d: unknown channel", id); 2713 2714 if (want_tty) { 2715 struct winsize ws; 2716 2717 /* Store window size in the packet. */ 2718 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2719 memset(&ws, 0, sizeof(ws)); 2720 2721 channel_request_start(ssh, id, "pty-req", 1); 2722 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2723 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2724 != 0 || 2725 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2726 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2727 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2728 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2729 fatal_fr(r, "build pty-req"); 2730 if (tiop == NULL) 2731 tiop = get_saved_tio(); 2732 ssh_tty_make_modes(ssh, -1, tiop); 2733 if ((r = sshpkt_send(ssh)) != 0) 2734 fatal_fr(r, "send pty-req"); 2735 /* XXX wait for reply */ 2736 c->client_tty = 1; 2737 } 2738 2739 /* Transfer any environment variables from client to server */ 2740 if (options.num_send_env != 0 && env != NULL) { 2741 debug("Sending environment."); 2742 for (i = 0; env[i] != NULL; i++) { 2743 /* Split */ 2744 name = xstrdup(env[i]); 2745 if ((val = strchr(name, '=')) == NULL) { 2746 free(name); 2747 continue; 2748 } 2749 *val++ = '\0'; 2750 2751 matched = 0; 2752 for (j = 0; j < options.num_send_env; j++) { 2753 if (match_pattern(name, options.send_env[j])) { 2754 matched = 1; 2755 break; 2756 } 2757 } 2758 if (!matched) { 2759 debug3("Ignored env %s", name); 2760 free(name); 2761 continue; 2762 } 2763 client_send_env(ssh, id, name, val); 2764 free(name); 2765 } 2766 } 2767 for (i = 0; i < options.num_setenv; i++) { 2768 /* Split */ 2769 name = xstrdup(options.setenv[i]); 2770 if ((val = strchr(name, '=')) == NULL) { 2771 free(name); 2772 continue; 2773 } 2774 *val++ = '\0'; 2775 client_send_env(ssh, id, name, val); 2776 free(name); 2777 } 2778 2779 len = sshbuf_len(cmd); 2780 if (len > 0) { 2781 if (len > 900) 2782 len = 900; 2783 if (want_subsystem) { 2784 debug("Sending subsystem: %.*s", 2785 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2786 channel_request_start(ssh, id, "subsystem", 1); 2787 client_expect_confirm(ssh, id, "subsystem", 2788 CONFIRM_CLOSE); 2789 } else { 2790 debug("Sending command: %.*s", 2791 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2792 channel_request_start(ssh, id, "exec", 1); 2793 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2794 } 2795 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2796 (r = sshpkt_send(ssh)) != 0) 2797 fatal_fr(r, "send command"); 2798 } else { 2799 channel_request_start(ssh, id, "shell", 1); 2800 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2801 if ((r = sshpkt_send(ssh)) != 0) 2802 fatal_fr(r, "send shell"); 2803 } 2804 2805 session_setup_complete = 1; 2806 client_repledge(); 2807 } 2808 2809 static void 2810 client_init_dispatch(struct ssh *ssh) 2811 { 2812 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2813 2814 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2815 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2816 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2817 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2818 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2819 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2820 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2821 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2822 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2823 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2824 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2825 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2826 2827 /* rekeying */ 2828 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2829 2830 /* global request reply messages */ 2831 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2832 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2833 } 2834 2835 void 2836 client_stop_mux(void) 2837 { 2838 if (options.control_path != NULL && muxserver_sock != -1) 2839 unlink(options.control_path); 2840 /* 2841 * If we are in persist mode, or don't have a shell, signal that we 2842 * should close when all active channels are closed. 2843 */ 2844 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2845 session_closed = 1; 2846 setproctitle("[stopped mux]"); 2847 } 2848 } 2849 2850 /* client specific fatal cleanup */ 2851 void 2852 cleanup_exit(int i) 2853 { 2854 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2855 if (options.control_path != NULL && muxserver_sock != -1) 2856 unlink(options.control_path); 2857 ssh_kill_proxy_command(); 2858 _exit(i); 2859 } 2860