1 /* $OpenBSD: clientloop.c,v 1.408 2024/07/01 04:31:17 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The main loop for the interactive session (client side). 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * 15 * Copyright (c) 1999 Theo de Raadt. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 * 37 * 38 * SSH2 support added by Markus Friedl. 39 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 50 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 51 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 52 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 53 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 54 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 55 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 56 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 57 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 58 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 59 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 60 */ 61 62 #include "includes.h" 63 64 #include <sys/types.h> 65 #include <sys/ioctl.h> 66 #ifdef HAVE_SYS_STAT_H 67 # include <sys/stat.h> 68 #endif 69 #ifdef HAVE_SYS_TIME_H 70 # include <sys/time.h> 71 #endif 72 #include <sys/socket.h> 73 74 #include <ctype.h> 75 #include <errno.h> 76 #ifdef HAVE_PATHS_H 77 #include <paths.h> 78 #endif 79 #ifdef HAVE_POLL_H 80 #include <poll.h> 81 #endif 82 #include <signal.h> 83 #include <stdio.h> 84 #include <stdlib.h> 85 #include <string.h> 86 #include <stdarg.h> 87 #include <termios.h> 88 #include <pwd.h> 89 #include <unistd.h> 90 #include <limits.h> 91 92 #include "openbsd-compat/sys-queue.h" 93 #include "xmalloc.h" 94 #include "ssh.h" 95 #include "ssh2.h" 96 #include "packet.h" 97 #include "sshbuf.h" 98 #include "compat.h" 99 #include "channels.h" 100 #include "dispatch.h" 101 #include "sshkey.h" 102 #include "cipher.h" 103 #include "kex.h" 104 #include "myproposal.h" 105 #include "log.h" 106 #include "misc.h" 107 #include "readconf.h" 108 #include "clientloop.h" 109 #include "sshconnect.h" 110 #include "authfd.h" 111 #include "atomicio.h" 112 #include "sshpty.h" 113 #include "match.h" 114 #include "msg.h" 115 #include "ssherr.h" 116 #include "hostfile.h" 117 118 /* Permitted RSA signature algorithms for UpdateHostkeys proofs */ 119 #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256" 120 121 /* Uncertainty (in percent) of keystroke timing intervals */ 122 #define SSH_KEYSTROKE_TIMING_FUZZ 10 123 124 /* import options */ 125 extern Options options; 126 127 /* Control socket */ 128 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */ 129 130 /* 131 * Name of the host we are connecting to. This is the name given on the 132 * command line, or the Hostname specified for the user-supplied name in a 133 * configuration file. 134 */ 135 extern char *host; 136 137 /* 138 * If this field is not NULL, the ForwardAgent socket is this path and different 139 * instead of SSH_AUTH_SOCK. 140 */ 141 extern char *forward_agent_sock_path; 142 143 /* 144 * Flag to indicate that we have received a window change signal which has 145 * not yet been processed. This will cause a message indicating the new 146 * window size to be sent to the server a little later. This is volatile 147 * because this is updated in a signal handler. 148 */ 149 static volatile sig_atomic_t received_window_change_signal = 0; 150 static volatile sig_atomic_t received_signal = 0; 151 152 /* Time when backgrounded control master using ControlPersist should exit */ 153 static time_t control_persist_exit_time = 0; 154 155 /* Common data for the client loop code. */ 156 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ 157 static int last_was_cr; /* Last character was a newline. */ 158 static int exit_status; /* Used to store the command exit status. */ 159 static int connection_in; /* Connection to server (input). */ 160 static int connection_out; /* Connection to server (output). */ 161 static int need_rekeying; /* Set to non-zero if rekeying is requested. */ 162 static int session_closed; /* In SSH2: login session closed. */ 163 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */ 164 static time_t server_alive_time; /* Time to do server_alive_check */ 165 static int hostkeys_update_complete; 166 static int session_setup_complete; 167 168 static void client_init_dispatch(struct ssh *ssh); 169 int session_ident = -1; 170 171 /* Track escape per proto2 channel */ 172 struct escape_filter_ctx { 173 int escape_pending; 174 int escape_char; 175 }; 176 177 /* Context for channel confirmation replies */ 178 struct channel_reply_ctx { 179 const char *request_type; 180 int id; 181 enum confirm_action action; 182 }; 183 184 /* Global request success/failure callbacks */ 185 /* XXX move to struct ssh? */ 186 struct global_confirm { 187 TAILQ_ENTRY(global_confirm) entry; 188 global_confirm_cb *cb; 189 void *ctx; 190 int ref_count; 191 }; 192 TAILQ_HEAD(global_confirms, global_confirm); 193 static struct global_confirms global_confirms = 194 TAILQ_HEAD_INITIALIZER(global_confirms); 195 196 static void quit_message(const char *fmt, ...) 197 __attribute__((__format__ (printf, 1, 2))); 198 199 static void 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 return 0; 665 666 /* Calculate number of intervals missed since the last check */ 667 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000; 668 n += now.tv_nsec - next_interval.tv_nsec; 669 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000; 670 n = (n < 0) ? 1 : n + 1; 671 672 /* Advance to the next interval */ 673 set_next_interval(&now, &next_interval, 674 options.obscure_keystroke_timing_interval * n, 0); 675 return 1; 676 } 677 678 /* 679 * Waits until the client can do something (some data becomes available on 680 * one of the file descriptors). 681 */ 682 static void 683 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp, 684 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue, 685 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp) 686 { 687 struct timespec timeout; 688 int ret, oready; 689 u_int p; 690 691 *conn_in_readyp = *conn_out_readyp = 0; 692 693 /* Prepare channel poll. First two pollfd entries are reserved */ 694 ptimeout_init(&timeout); 695 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 696 if (*npfd_activep < 2) 697 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 698 699 /* channel_prepare_poll could have closed the last channel */ 700 if (session_closed && !channel_still_open(ssh) && 701 !ssh_packet_have_data_to_write(ssh)) { 702 /* clear events since we did not call poll() */ 703 for (p = 0; p < *npfd_activep; p++) 704 (*pfdp)[p].revents = 0; 705 return; 706 } 707 708 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue); 709 710 /* Monitor server connection on reserved pollfd entries */ 711 (*pfdp)[0].fd = connection_in; 712 (*pfdp)[0].events = POLLIN; 713 (*pfdp)[1].fd = connection_out; 714 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ? 715 POLLOUT : 0; 716 717 /* 718 * Wait for something to happen. This will suspend the process until 719 * some polled descriptor can be read, written, or has some other 720 * event pending, or a timeout expires. 721 */ 722 set_control_persist_exit_time(ssh); 723 if (control_persist_exit_time > 0) 724 ptimeout_deadline_monotime(&timeout, control_persist_exit_time); 725 if (options.server_alive_interval > 0) 726 ptimeout_deadline_monotime(&timeout, server_alive_time); 727 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 728 ptimeout_deadline_sec(&timeout, 729 ssh_packet_get_rekey_timeout(ssh)); 730 } 731 732 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp); 733 734 if (ret == -1) { 735 /* 736 * We have to clear the events because we return. 737 * We have to return, because the mainloop checks for the flags 738 * set by the signal handlers. 739 */ 740 for (p = 0; p < *npfd_activep; p++) 741 (*pfdp)[p].revents = 0; 742 if (errno == EINTR) 743 return; 744 /* Note: we might still have data in the buffers. */ 745 quit_message("poll: %s", strerror(errno)); 746 return; 747 } 748 749 *conn_in_readyp = (*pfdp)[0].revents != 0; 750 *conn_out_readyp = (*pfdp)[1].revents != 0; 751 752 if (options.server_alive_interval > 0 && !*conn_in_readyp && 753 monotime() >= server_alive_time) { 754 /* 755 * ServerAlive check is needed. We can't rely on the poll 756 * timing out since traffic on the client side such as port 757 * forwards can keep waking it up. 758 */ 759 server_alive_check(ssh); 760 } 761 } 762 763 static void 764 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr) 765 { 766 /* Flush stdout and stderr buffers. */ 767 if (sshbuf_len(bout) > 0) 768 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout), 769 sshbuf_len(bout)); 770 if (sshbuf_len(berr) > 0) 771 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr), 772 sshbuf_len(berr)); 773 774 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 775 776 sshbuf_reset(bin); 777 sshbuf_reset(bout); 778 sshbuf_reset(berr); 779 780 /* Send the suspend signal to the program itself. */ 781 kill(getpid(), SIGTSTP); 782 783 /* Reset window sizes in case they have changed */ 784 received_window_change_signal = 1; 785 786 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 787 } 788 789 static void 790 client_process_net_input(struct ssh *ssh) 791 { 792 int r; 793 794 /* 795 * Read input from the server, and add any such data to the buffer of 796 * the packet subsystem. 797 */ 798 schedule_server_alive_check(); 799 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 800 return; /* success */ 801 if (r == SSH_ERR_SYSTEM_ERROR) { 802 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK) 803 return; 804 if (errno == EPIPE) { 805 quit_message("Connection to %s closed by remote host.", 806 host); 807 return; 808 } 809 } 810 quit_message("Read from remote host %s: %s", host, ssh_err(r)); 811 } 812 813 static void 814 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) 815 { 816 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; 817 char errmsg[256]; 818 int r, tochan; 819 820 /* 821 * If a TTY was explicitly requested, then a failure to allocate 822 * one is fatal. 823 */ 824 if (cr->action == CONFIRM_TTY && 825 (options.request_tty == REQUEST_TTY_FORCE || 826 options.request_tty == REQUEST_TTY_YES)) 827 cr->action = CONFIRM_CLOSE; 828 829 /* XXX suppress on mux _client_ quietmode */ 830 tochan = options.log_level >= SYSLOG_LEVEL_ERROR && 831 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; 832 833 if (type == SSH2_MSG_CHANNEL_SUCCESS) { 834 debug2("%s request accepted on channel %d", 835 cr->request_type, c->self); 836 } else if (type == SSH2_MSG_CHANNEL_FAILURE) { 837 if (tochan) { 838 snprintf(errmsg, sizeof(errmsg), 839 "%s request failed\r\n", cr->request_type); 840 } else { 841 snprintf(errmsg, sizeof(errmsg), 842 "%s request failed on channel %d", 843 cr->request_type, c->self); 844 } 845 /* If error occurred on primary session channel, then exit */ 846 if (cr->action == CONFIRM_CLOSE && c->self == session_ident) 847 fatal("%s", errmsg); 848 /* 849 * If error occurred on mux client, append to 850 * their stderr. 851 */ 852 if (tochan) { 853 debug3_f("channel %d: mux request: %s", c->self, 854 cr->request_type); 855 if ((r = sshbuf_put(c->extended, errmsg, 856 strlen(errmsg))) != 0) 857 fatal_fr(r, "sshbuf_put"); 858 } else 859 error("%s", errmsg); 860 if (cr->action == CONFIRM_TTY) { 861 /* 862 * If a TTY allocation error occurred, then arrange 863 * for the correct TTY to leave raw mode. 864 */ 865 if (c->self == session_ident) 866 leave_raw_mode(0); 867 else 868 mux_tty_alloc_failed(ssh, c); 869 } else if (cr->action == CONFIRM_CLOSE) { 870 chan_read_failed(ssh, c); 871 chan_write_failed(ssh, c); 872 } 873 } 874 free(cr); 875 } 876 877 static void 878 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) 879 { 880 free(ctx); 881 } 882 883 void 884 client_expect_confirm(struct ssh *ssh, int id, const char *request, 885 enum confirm_action action) 886 { 887 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); 888 889 cr->request_type = request; 890 cr->action = action; 891 892 channel_register_status_confirm(ssh, id, client_status_confirm, 893 client_abandon_status_confirm, cr); 894 } 895 896 void 897 client_register_global_confirm(global_confirm_cb *cb, void *ctx) 898 { 899 struct global_confirm *gc, *last_gc; 900 901 /* Coalesce identical callbacks */ 902 last_gc = TAILQ_LAST(&global_confirms, global_confirms); 903 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { 904 if (++last_gc->ref_count >= INT_MAX) 905 fatal_f("last_gc->ref_count = %d", 906 last_gc->ref_count); 907 return; 908 } 909 910 gc = xcalloc(1, sizeof(*gc)); 911 gc->cb = cb; 912 gc->ctx = ctx; 913 gc->ref_count = 1; 914 TAILQ_INSERT_TAIL(&global_confirms, gc, entry); 915 } 916 917 /* 918 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com 919 * hostkey update request. 920 */ 921 static int 922 can_update_hostkeys(void) 923 { 924 if (hostkeys_update_complete) 925 return 0; 926 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && 927 options.batch_mode) 928 return 0; /* won't ask in batchmode, so don't even try */ 929 if (!options.update_hostkeys || options.num_user_hostfiles <= 0) 930 return 0; 931 return 1; 932 } 933 934 static void 935 client_repledge(void) 936 { 937 debug3_f("enter"); 938 939 /* Might be able to tighten pledge now that session is established */ 940 if (options.control_master || options.control_path != NULL || 941 options.forward_x11 || options.fork_after_authentication || 942 can_update_hostkeys() || 943 (session_ident != -1 && !session_setup_complete)) { 944 /* Can't tighten */ 945 return; 946 } 947 /* 948 * LocalCommand and UpdateHostkeys have finished, so can get rid of 949 * filesystem. 950 * 951 * XXX protocol allows a server can to change hostkeys during the 952 * connection at rekey time that could trigger a hostkeys update 953 * but AFAIK no implementations support this. Could improve by 954 * forcing known_hosts to be read-only or via unveil(2). 955 */ 956 if (options.num_local_forwards != 0 || 957 options.num_remote_forwards != 0 || 958 options.num_permitted_remote_opens != 0 || 959 options.enable_escape_commandline != 0) { 960 /* rfwd needs inet */ 961 debug("pledge: network"); 962 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 963 fatal_f("pledge(): %s", strerror(errno)); 964 } else if (options.forward_agent != 0) { 965 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */ 966 debug("pledge: agent"); 967 if (pledge("stdio unix proc tty", NULL) == -1) 968 fatal_f("pledge(): %s", strerror(errno)); 969 } else { 970 debug("pledge: fork"); 971 if (pledge("stdio proc tty", NULL) == -1) 972 fatal_f("pledge(): %s", strerror(errno)); 973 } 974 /* XXX further things to do: 975 * 976 * - might be able to get rid of proc if we kill ~^Z 977 * - ssh -N (no session) 978 * - stdio forwarding 979 * - sessions without tty 980 */ 981 } 982 983 static void 984 process_cmdline(struct ssh *ssh) 985 { 986 void (*handler)(int); 987 char *s, *cmd; 988 int ok, delete = 0, local = 0, remote = 0, dynamic = 0; 989 struct Forward fwd; 990 991 memset(&fwd, 0, sizeof(fwd)); 992 993 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 994 handler = ssh_signal(SIGINT, SIG_IGN); 995 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); 996 if (s == NULL) 997 goto out; 998 while (isspace((u_char)*s)) 999 s++; 1000 if (*s == '-') 1001 s++; /* Skip cmdline '-', if any */ 1002 if (*s == '\0') 1003 goto out; 1004 1005 if (*s == 'h' || *s == 'H' || *s == '?') { 1006 logit("Commands:"); 1007 logit(" -L[bind_address:]port:host:hostport " 1008 "Request local forward"); 1009 logit(" -R[bind_address:]port:host:hostport " 1010 "Request remote forward"); 1011 logit(" -D[bind_address:]port " 1012 "Request dynamic forward"); 1013 logit(" -KL[bind_address:]port " 1014 "Cancel local forward"); 1015 logit(" -KR[bind_address:]port " 1016 "Cancel remote forward"); 1017 logit(" -KD[bind_address:]port " 1018 "Cancel dynamic forward"); 1019 if (!options.permit_local_command) 1020 goto out; 1021 logit(" !args " 1022 "Execute local command"); 1023 goto out; 1024 } 1025 1026 if (*s == '!' && options.permit_local_command) { 1027 s++; 1028 ssh_local_cmd(s); 1029 goto out; 1030 } 1031 1032 if (*s == 'K') { 1033 delete = 1; 1034 s++; 1035 } 1036 if (*s == 'L') 1037 local = 1; 1038 else if (*s == 'R') 1039 remote = 1; 1040 else if (*s == 'D') 1041 dynamic = 1; 1042 else { 1043 logit("Invalid command."); 1044 goto out; 1045 } 1046 1047 while (isspace((u_char)*++s)) 1048 ; 1049 1050 /* XXX update list of forwards in options */ 1051 if (delete) { 1052 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ 1053 if (!parse_forward(&fwd, s, 1, 0)) { 1054 logit("Bad forwarding close specification."); 1055 goto out; 1056 } 1057 if (remote) 1058 ok = channel_request_rforward_cancel(ssh, &fwd) == 0; 1059 else if (dynamic) 1060 ok = channel_cancel_lport_listener(ssh, &fwd, 1061 0, &options.fwd_opts) > 0; 1062 else 1063 ok = channel_cancel_lport_listener(ssh, &fwd, 1064 CHANNEL_CANCEL_PORT_STATIC, 1065 &options.fwd_opts) > 0; 1066 if (!ok) { 1067 logit("Unknown port forwarding."); 1068 goto out; 1069 } 1070 logit("Canceled forwarding."); 1071 } else { 1072 /* -R specs can be both dynamic or not, so check both. */ 1073 if (remote) { 1074 if (!parse_forward(&fwd, s, 0, remote) && 1075 !parse_forward(&fwd, s, 1, remote)) { 1076 logit("Bad remote forwarding specification."); 1077 goto out; 1078 } 1079 } else if (!parse_forward(&fwd, s, dynamic, remote)) { 1080 logit("Bad local forwarding specification."); 1081 goto out; 1082 } 1083 if (local || dynamic) { 1084 if (!channel_setup_local_fwd_listener(ssh, &fwd, 1085 &options.fwd_opts)) { 1086 logit("Port forwarding failed."); 1087 goto out; 1088 } 1089 } else { 1090 if (channel_request_remote_forwarding(ssh, &fwd) < 0) { 1091 logit("Port forwarding failed."); 1092 goto out; 1093 } 1094 } 1095 logit("Forwarding port."); 1096 } 1097 1098 out: 1099 ssh_signal(SIGINT, handler); 1100 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1101 free(cmd); 1102 free(fwd.listen_host); 1103 free(fwd.listen_path); 1104 free(fwd.connect_host); 1105 free(fwd.connect_path); 1106 } 1107 1108 /* reasons to suppress output of an escape command in help output */ 1109 #define SUPPRESS_NEVER 0 /* never suppress, always show */ 1110 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ 1111 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ 1112 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ 1113 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/ 1114 struct escape_help_text { 1115 const char *cmd; 1116 const char *text; 1117 unsigned int flags; 1118 }; 1119 static struct escape_help_text esc_txt[] = { 1120 {".", "terminate session", SUPPRESS_MUXMASTER}, 1121 {".", "terminate connection (and any multiplexed sessions)", 1122 SUPPRESS_MUXCLIENT}, 1123 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, 1124 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE}, 1125 {"R", "request rekey", SUPPRESS_NEVER}, 1126 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, 1127 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, 1128 {"#", "list forwarded connections", SUPPRESS_NEVER}, 1129 {"&", "background ssh (when waiting for connections to terminate)", 1130 SUPPRESS_MUXCLIENT}, 1131 {"?", "this message", SUPPRESS_NEVER}, 1132 }; 1133 1134 static void 1135 print_escape_help(struct sshbuf *b, int escape_char, int mux_client, 1136 int using_stderr) 1137 { 1138 unsigned int i, suppress_flags; 1139 int r; 1140 1141 if ((r = sshbuf_putf(b, 1142 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0) 1143 fatal_fr(r, "sshbuf_putf"); 1144 1145 suppress_flags = 1146 (mux_client ? SUPPRESS_MUXCLIENT : 0) | 1147 (mux_client ? 0 : SUPPRESS_MUXMASTER) | 1148 (using_stderr ? 0 : SUPPRESS_SYSLOG) | 1149 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0); 1150 1151 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { 1152 if (esc_txt[i].flags & suppress_flags) 1153 continue; 1154 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n", 1155 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0) 1156 fatal_fr(r, "sshbuf_putf"); 1157 } 1158 1159 if ((r = sshbuf_putf(b, 1160 " %c%c - send the escape character by typing it twice\r\n" 1161 "(Note that escapes are only recognized immediately after " 1162 "newline.)\r\n", escape_char, escape_char)) != 0) 1163 fatal_fr(r, "sshbuf_putf"); 1164 } 1165 1166 /* 1167 * Process the characters one by one. 1168 */ 1169 static int 1170 process_escapes(struct ssh *ssh, Channel *c, 1171 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr, 1172 char *buf, int len) 1173 { 1174 pid_t pid; 1175 int r, bytes = 0; 1176 u_int i; 1177 u_char ch; 1178 char *s; 1179 struct escape_filter_ctx *efc; 1180 1181 if (c == NULL || c->filter_ctx == NULL || len <= 0) 1182 return 0; 1183 1184 efc = (struct escape_filter_ctx *)c->filter_ctx; 1185 1186 for (i = 0; i < (u_int)len; i++) { 1187 /* Get one character at a time. */ 1188 ch = buf[i]; 1189 1190 if (efc->escape_pending) { 1191 /* We have previously seen an escape character. */ 1192 /* Clear the flag now. */ 1193 efc->escape_pending = 0; 1194 1195 /* Process the escaped character. */ 1196 switch (ch) { 1197 case '.': 1198 /* Terminate the connection. */ 1199 if ((r = sshbuf_putf(berr, "%c.\r\n", 1200 efc->escape_char)) != 0) 1201 fatal_fr(r, "sshbuf_putf"); 1202 if (c && c->ctl_chan != -1) { 1203 channel_force_close(ssh, c, 1); 1204 return 0; 1205 } else 1206 quit_pending = 1; 1207 return -1; 1208 1209 case 'Z' - 64: 1210 /* XXX support this for mux clients */ 1211 if (c && c->ctl_chan != -1) { 1212 char b[16]; 1213 noescape: 1214 if (ch == 'Z' - 64) 1215 snprintf(b, sizeof b, "^Z"); 1216 else 1217 snprintf(b, sizeof b, "%c", ch); 1218 if ((r = sshbuf_putf(berr, 1219 "%c%s escape not available to " 1220 "multiplexed sessions\r\n", 1221 efc->escape_char, b)) != 0) 1222 fatal_fr(r, "sshbuf_putf"); 1223 continue; 1224 } 1225 /* Suspend the program. Inform the user */ 1226 if ((r = sshbuf_putf(berr, 1227 "%c^Z [suspend ssh]\r\n", 1228 efc->escape_char)) != 0) 1229 fatal_fr(r, "sshbuf_putf"); 1230 1231 /* Restore terminal modes and suspend. */ 1232 client_suspend_self(bin, bout, berr); 1233 1234 /* We have been continued. */ 1235 continue; 1236 1237 case 'B': 1238 if ((r = sshbuf_putf(berr, 1239 "%cB\r\n", efc->escape_char)) != 0) 1240 fatal_fr(r, "sshbuf_putf"); 1241 channel_request_start(ssh, c->self, "break", 0); 1242 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 || 1243 (r = sshpkt_send(ssh)) != 0) 1244 fatal_fr(r, "send packet"); 1245 continue; 1246 1247 case 'R': 1248 if (ssh->compat & SSH_BUG_NOREKEY) 1249 logit("Server does not " 1250 "support re-keying"); 1251 else 1252 need_rekeying = 1; 1253 continue; 1254 1255 case 'V': 1256 /* FALLTHROUGH */ 1257 case 'v': 1258 if (c && c->ctl_chan != -1) 1259 goto noescape; 1260 if (!log_is_on_stderr()) { 1261 if ((r = sshbuf_putf(berr, 1262 "%c%c [Logging to syslog]\r\n", 1263 efc->escape_char, ch)) != 0) 1264 fatal_fr(r, "sshbuf_putf"); 1265 continue; 1266 } 1267 if (ch == 'V' && options.log_level > 1268 SYSLOG_LEVEL_QUIET) 1269 log_change_level(--options.log_level); 1270 if (ch == 'v' && options.log_level < 1271 SYSLOG_LEVEL_DEBUG3) 1272 log_change_level(++options.log_level); 1273 if ((r = sshbuf_putf(berr, 1274 "%c%c [LogLevel %s]\r\n", 1275 efc->escape_char, ch, 1276 log_level_name(options.log_level))) != 0) 1277 fatal_fr(r, "sshbuf_putf"); 1278 continue; 1279 1280 case '&': 1281 if (c->ctl_chan != -1) 1282 goto noescape; 1283 /* 1284 * Detach the program (continue to serve 1285 * connections, but put in background and no 1286 * more new connections). 1287 */ 1288 /* Restore tty modes. */ 1289 leave_raw_mode( 1290 options.request_tty == REQUEST_TTY_FORCE); 1291 1292 /* Stop listening for new connections. */ 1293 channel_stop_listening(ssh); 1294 1295 if ((r = sshbuf_putf(berr, "%c& " 1296 "[backgrounded]\n", efc->escape_char)) != 0) 1297 fatal_fr(r, "sshbuf_putf"); 1298 1299 /* Fork into background. */ 1300 pid = fork(); 1301 if (pid == -1) { 1302 error("fork: %.100s", strerror(errno)); 1303 continue; 1304 } 1305 if (pid != 0) { /* This is the parent. */ 1306 /* The parent just exits. */ 1307 exit(0); 1308 } 1309 /* The child continues serving connections. */ 1310 /* fake EOF on stdin */ 1311 if ((r = sshbuf_put_u8(bin, 4)) != 0) 1312 fatal_fr(r, "sshbuf_put_u8"); 1313 return -1; 1314 case '?': 1315 print_escape_help(berr, efc->escape_char, 1316 (c && c->ctl_chan != -1), 1317 log_is_on_stderr()); 1318 continue; 1319 1320 case '#': 1321 if ((r = sshbuf_putf(berr, "%c#\r\n", 1322 efc->escape_char)) != 0) 1323 fatal_fr(r, "sshbuf_putf"); 1324 s = channel_open_message(ssh); 1325 if ((r = sshbuf_put(berr, s, strlen(s))) != 0) 1326 fatal_fr(r, "sshbuf_put"); 1327 free(s); 1328 continue; 1329 1330 case 'C': 1331 if (c && c->ctl_chan != -1) 1332 goto noescape; 1333 if (options.enable_escape_commandline == 0) { 1334 if ((r = sshbuf_putf(berr, 1335 "commandline disabled\r\n")) != 0) 1336 fatal_fr(r, "sshbuf_putf"); 1337 continue; 1338 } 1339 process_cmdline(ssh); 1340 continue; 1341 1342 default: 1343 if (ch != efc->escape_char) { 1344 if ((r = sshbuf_put_u8(bin, 1345 efc->escape_char)) != 0) 1346 fatal_fr(r, "sshbuf_put_u8"); 1347 bytes++; 1348 } 1349 /* Escaped characters fall through here */ 1350 break; 1351 } 1352 } else { 1353 /* 1354 * The previous character was not an escape char. 1355 * Check if this is an escape. 1356 */ 1357 if (last_was_cr && ch == efc->escape_char) { 1358 /* 1359 * It is. Set the flag and continue to 1360 * next character. 1361 */ 1362 efc->escape_pending = 1; 1363 continue; 1364 } 1365 } 1366 1367 /* 1368 * Normal character. Record whether it was a newline, 1369 * and append it to the buffer. 1370 */ 1371 last_was_cr = (ch == '\r' || ch == '\n'); 1372 if ((r = sshbuf_put_u8(bin, ch)) != 0) 1373 fatal_fr(r, "sshbuf_put_u8"); 1374 bytes++; 1375 } 1376 return bytes; 1377 } 1378 1379 /* 1380 * Get packets from the connection input buffer, and process them as long as 1381 * there are packets available. 1382 * 1383 * Any unknown packets received during the actual 1384 * session cause the session to terminate. This is 1385 * intended to make debugging easier since no 1386 * confirmations are sent. Any compatible protocol 1387 * extensions must be negotiated during the 1388 * preparatory phase. 1389 */ 1390 1391 static void 1392 client_process_buffered_input_packets(struct ssh *ssh) 1393 { 1394 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending); 1395 } 1396 1397 /* scan buf[] for '~' before sending data to the peer */ 1398 1399 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ 1400 void * 1401 client_new_escape_filter_ctx(int escape_char) 1402 { 1403 struct escape_filter_ctx *ret; 1404 1405 ret = xcalloc(1, sizeof(*ret)); 1406 ret->escape_pending = 0; 1407 ret->escape_char = escape_char; 1408 return (void *)ret; 1409 } 1410 1411 /* Free the escape filter context on channel free */ 1412 void 1413 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) 1414 { 1415 free(ctx); 1416 } 1417 1418 int 1419 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len) 1420 { 1421 if (c->extended_usage != CHAN_EXTENDED_WRITE) 1422 return 0; 1423 1424 return process_escapes(ssh, c, c->input, c->output, c->extended, 1425 buf, len); 1426 } 1427 1428 static void 1429 client_channel_closed(struct ssh *ssh, int id, int force, void *arg) 1430 { 1431 channel_cancel_cleanup(ssh, id); 1432 session_closed = 1; 1433 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1434 } 1435 1436 /* 1437 * Implements the interactive session with the server. This is called after 1438 * the user has been authenticated, and a command has been started on the 1439 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character 1440 * used as an escape character for terminating or suspending the session. 1441 */ 1442 int 1443 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, 1444 int ssh2_chan_id) 1445 { 1446 struct pollfd *pfd = NULL; 1447 u_int npfd_alloc = 0, npfd_active = 0; 1448 double start_time, total_time; 1449 int channel_did_enqueue = 0, r; 1450 u_int64_t ibytes, obytes; 1451 int conn_in_ready, conn_out_ready; 1452 sigset_t bsigset, osigset; 1453 1454 debug("Entering interactive session."); 1455 session_ident = ssh2_chan_id; 1456 1457 if (options.control_master && 1458 !option_clear_or_none(options.control_path)) { 1459 debug("pledge: id"); 1460 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty", 1461 NULL) == -1) 1462 fatal_f("pledge(): %s", strerror(errno)); 1463 1464 } else if (options.forward_x11 || options.permit_local_command) { 1465 debug("pledge: exec"); 1466 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty", 1467 NULL) == -1) 1468 fatal_f("pledge(): %s", strerror(errno)); 1469 1470 } else if (options.update_hostkeys) { 1471 debug("pledge: filesystem"); 1472 if (pledge("stdio rpath wpath cpath unix inet dns proc tty", 1473 NULL) == -1) 1474 fatal_f("pledge(): %s", strerror(errno)); 1475 1476 } else if (!option_clear_or_none(options.proxy_command) || 1477 options.fork_after_authentication) { 1478 debug("pledge: proc"); 1479 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1) 1480 fatal_f("pledge(): %s", strerror(errno)); 1481 1482 } else { 1483 debug("pledge: network"); 1484 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 1485 fatal_f("pledge(): %s", strerror(errno)); 1486 } 1487 1488 /* might be able to tighten now */ 1489 client_repledge(); 1490 1491 start_time = monotime_double(); 1492 1493 /* Initialize variables. */ 1494 last_was_cr = 1; 1495 exit_status = -1; 1496 connection_in = ssh_packet_get_connection_in(ssh); 1497 connection_out = ssh_packet_get_connection_out(ssh); 1498 1499 quit_pending = 0; 1500 1501 client_init_dispatch(ssh); 1502 1503 /* 1504 * Set signal handlers, (e.g. to restore non-blocking mode) 1505 * but don't overwrite SIG_IGN, matches behaviour from rsh(1) 1506 */ 1507 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN) 1508 ssh_signal(SIGHUP, signal_handler); 1509 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN) 1510 ssh_signal(SIGINT, signal_handler); 1511 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN) 1512 ssh_signal(SIGQUIT, signal_handler); 1513 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN) 1514 ssh_signal(SIGTERM, signal_handler); 1515 ssh_signal(SIGWINCH, window_change_handler); 1516 1517 if (have_pty) 1518 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1519 1520 if (session_ident != -1) { 1521 if (escape_char_arg != SSH_ESCAPECHAR_NONE) { 1522 channel_register_filter(ssh, session_ident, 1523 client_simple_escape_filter, NULL, 1524 client_filter_cleanup, 1525 client_new_escape_filter_ctx( 1526 escape_char_arg)); 1527 } 1528 channel_register_cleanup(ssh, session_ident, 1529 client_channel_closed, 0); 1530 } 1531 1532 schedule_server_alive_check(); 1533 1534 if (sigemptyset(&bsigset) == -1 || 1535 sigaddset(&bsigset, SIGHUP) == -1 || 1536 sigaddset(&bsigset, SIGINT) == -1 || 1537 sigaddset(&bsigset, SIGQUIT) == -1 || 1538 sigaddset(&bsigset, SIGTERM) == -1) 1539 error_f("bsigset setup: %s", strerror(errno)); 1540 1541 /* Main loop of the client for the interactive session mode. */ 1542 while (!quit_pending) { 1543 channel_did_enqueue = 0; 1544 1545 /* Process buffered packets sent by the server. */ 1546 client_process_buffered_input_packets(ssh); 1547 1548 if (session_closed && !channel_still_open(ssh)) 1549 break; 1550 1551 if (ssh_packet_is_rekeying(ssh)) { 1552 debug("rekeying in progress"); 1553 } else if (need_rekeying) { 1554 /* manual rekey request */ 1555 debug("need rekeying"); 1556 if ((r = kex_start_rekex(ssh)) != 0) 1557 fatal_fr(r, "kex_start_rekex"); 1558 need_rekeying = 0; 1559 } else { 1560 /* 1561 * Make packets from buffered channel data, and 1562 * enqueue them for sending to the server. 1563 */ 1564 if (ssh_packet_not_very_much_data_to_write(ssh)) 1565 channel_did_enqueue = channel_output_poll(ssh); 1566 1567 /* 1568 * Check if the window size has changed, and buffer a 1569 * message about it to the server if so. 1570 */ 1571 client_check_window_change(ssh); 1572 } 1573 /* 1574 * Wait until we have something to do (something becomes 1575 * available on one of the descriptors). 1576 */ 1577 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1) 1578 error_f("bsigset sigprocmask: %s", strerror(errno)); 1579 if (quit_pending) 1580 break; 1581 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc, 1582 &npfd_active, channel_did_enqueue, &osigset, 1583 &conn_in_ready, &conn_out_ready); 1584 if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1) 1585 error_f("osigset sigprocmask: %s", strerror(errno)); 1586 1587 if (quit_pending) 1588 break; 1589 1590 /* Do channel operations. */ 1591 channel_after_poll(ssh, pfd, npfd_active); 1592 1593 /* Buffer input from the connection. */ 1594 if (conn_in_ready) 1595 client_process_net_input(ssh); 1596 1597 if (quit_pending) 1598 break; 1599 1600 /* A timeout may have triggered rekeying */ 1601 if ((r = ssh_packet_check_rekey(ssh)) != 0) 1602 fatal_fr(r, "cannot start rekeying"); 1603 1604 /* 1605 * Send as much buffered packet data as possible to the 1606 * sender. 1607 */ 1608 if (conn_out_ready) { 1609 if ((r = ssh_packet_write_poll(ssh)) != 0) { 1610 sshpkt_fatal(ssh, r, 1611 "%s: ssh_packet_write_poll", __func__); 1612 } 1613 } 1614 1615 /* 1616 * If we are a backgrounded control master, and the 1617 * timeout has expired without any active client 1618 * connections, then quit. 1619 */ 1620 if (control_persist_exit_time > 0) { 1621 if (monotime() >= control_persist_exit_time) { 1622 debug("ControlPersist timeout expired"); 1623 break; 1624 } 1625 } 1626 } 1627 free(pfd); 1628 1629 /* Terminate the session. */ 1630 1631 /* 1632 * In interactive mode (with pseudo tty) display a message indicating 1633 * that the connection has been closed. 1634 */ 1635 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO) 1636 quit_message("Connection to %s closed.", host); 1637 1638 1639 /* Stop watching for window change. */ 1640 ssh_signal(SIGWINCH, SIG_DFL); 1641 1642 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || 1643 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 || 1644 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 || 1645 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */ 1646 (r = sshpkt_send(ssh)) != 0 || 1647 (r = ssh_packet_write_wait(ssh)) != 0) 1648 fatal_fr(r, "send disconnect"); 1649 1650 channel_free_all(ssh); 1651 1652 if (have_pty) 1653 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1654 1655 /* 1656 * If there was no shell or command requested, there will be no remote 1657 * exit status to be returned. In that case, clear error code if the 1658 * connection was deliberately terminated at this end. 1659 */ 1660 if (options.session_type == SESSION_TYPE_NONE && 1661 received_signal == SIGTERM) { 1662 received_signal = 0; 1663 exit_status = 0; 1664 } 1665 1666 if (received_signal) { 1667 verbose("Killed by signal %d.", (int) received_signal); 1668 cleanup_exit(255); 1669 } 1670 1671 /* Report bytes transferred, and transfer rates. */ 1672 total_time = monotime_double() - start_time; 1673 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1674 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", 1675 (unsigned long long)obytes, (unsigned long long)ibytes, total_time); 1676 if (total_time > 0) 1677 verbose("Bytes per second: sent %.1f, received %.1f", 1678 obytes / total_time, ibytes / total_time); 1679 /* Return the exit status of the program. */ 1680 debug("Exit status %d", exit_status); 1681 return exit_status; 1682 } 1683 1684 /*********/ 1685 1686 static Channel * 1687 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, 1688 int rchan, u_int rwindow, u_int rmaxpack) 1689 { 1690 Channel *c = NULL; 1691 struct sshbuf *b = NULL; 1692 char *listen_address, *originator_address; 1693 u_int listen_port, originator_port; 1694 int r; 1695 1696 /* Get rest of the packet */ 1697 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 || 1698 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 || 1699 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 || 1700 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1701 (r = sshpkt_get_end(ssh)) != 0) 1702 fatal_fr(r, "parse packet"); 1703 1704 debug_f("listen %s port %d, originator %s port %d", 1705 listen_address, listen_port, originator_address, originator_port); 1706 1707 if (listen_port > 0xffff) 1708 error_f("invalid listen port"); 1709 else if (originator_port > 0xffff) 1710 error_f("invalid originator port"); 1711 else { 1712 c = channel_connect_by_listen_address(ssh, 1713 listen_address, listen_port, "forwarded-tcpip", 1714 originator_address); 1715 } 1716 1717 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1718 if ((b = sshbuf_new()) == NULL) { 1719 error_f("alloc reply"); 1720 goto out; 1721 } 1722 /* reconstruct and send to muxclient */ 1723 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ 1724 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1725 (r = sshbuf_put_cstring(b, request_type)) != 0 || 1726 (r = sshbuf_put_u32(b, rchan)) != 0 || 1727 (r = sshbuf_put_u32(b, rwindow)) != 0 || 1728 (r = sshbuf_put_u32(b, rmaxpack)) != 0 || 1729 (r = sshbuf_put_cstring(b, listen_address)) != 0 || 1730 (r = sshbuf_put_u32(b, listen_port)) != 0 || 1731 (r = sshbuf_put_cstring(b, originator_address)) != 0 || 1732 (r = sshbuf_put_u32(b, originator_port)) != 0 || 1733 (r = sshbuf_put_stringb(c->output, b)) != 0) { 1734 error_fr(r, "compose for muxclient"); 1735 goto out; 1736 } 1737 } 1738 1739 out: 1740 sshbuf_free(b); 1741 free(originator_address); 1742 free(listen_address); 1743 return c; 1744 } 1745 1746 static Channel * 1747 client_request_forwarded_streamlocal(struct ssh *ssh, 1748 const char *request_type, int rchan) 1749 { 1750 Channel *c = NULL; 1751 char *listen_path; 1752 int r; 1753 1754 /* Get the remote path. */ 1755 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 || 1756 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */ 1757 (r = sshpkt_get_end(ssh)) != 0) 1758 fatal_fr(r, "parse packet"); 1759 1760 debug_f("request: %s", listen_path); 1761 1762 c = channel_connect_by_listen_path(ssh, listen_path, 1763 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); 1764 free(listen_path); 1765 return c; 1766 } 1767 1768 static Channel * 1769 client_request_x11(struct ssh *ssh, const char *request_type, int rchan) 1770 { 1771 Channel *c = NULL; 1772 char *originator; 1773 u_int originator_port; 1774 int r, sock; 1775 1776 if (!options.forward_x11) { 1777 error("Warning: ssh server tried X11 forwarding."); 1778 error("Warning: this is probably a break-in attempt by a " 1779 "malicious server."); 1780 return NULL; 1781 } 1782 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) { 1783 verbose("Rejected X11 connection after ForwardX11Timeout " 1784 "expired"); 1785 return NULL; 1786 } 1787 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 1788 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1789 (r = sshpkt_get_end(ssh)) != 0) 1790 fatal_fr(r, "parse packet"); 1791 /* XXX check permission */ 1792 /* XXX range check originator port? */ 1793 debug("client_request_x11: request from %s %u", originator, 1794 originator_port); 1795 free(originator); 1796 sock = x11_connect_display(ssh); 1797 if (sock < 0) 1798 return NULL; 1799 c = channel_new(ssh, "x11-connection", 1800 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1801 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1802 c->force_drain = 1; 1803 return c; 1804 } 1805 1806 static Channel * 1807 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1808 { 1809 Channel *c = NULL; 1810 int r, sock; 1811 1812 if (!options.forward_agent) { 1813 error("Warning: ssh server tried agent forwarding."); 1814 error("Warning: this is probably a break-in attempt by a " 1815 "malicious server."); 1816 return NULL; 1817 } 1818 if (forward_agent_sock_path == NULL) { 1819 r = ssh_get_authentication_socket(&sock); 1820 } else { 1821 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1822 } 1823 if (r != 0) { 1824 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1825 debug_fr(r, "ssh_get_authentication_socket"); 1826 return NULL; 1827 } 1828 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1829 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1830 debug_f("bound agent to hostkey"); 1831 else 1832 debug2_fr(r, "ssh_agent_bind_hostkey"); 1833 1834 c = channel_new(ssh, "agent-connection", 1835 SSH_CHANNEL_OPEN, sock, sock, -1, 1836 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1837 "authentication agent connection", 1); 1838 c->force_drain = 1; 1839 return c; 1840 } 1841 1842 char * 1843 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1844 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1845 { 1846 Channel *c; 1847 int r, fd; 1848 char *ifname = NULL; 1849 1850 if (tun_mode == SSH_TUNMODE_NO) 1851 return 0; 1852 1853 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1854 1855 /* Open local tunnel device */ 1856 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1857 error("Tunnel device open failed."); 1858 return NULL; 1859 } 1860 debug("Tunnel forwarding using interface %s", ifname); 1861 1862 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1863 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1864 c->datagram = 1; 1865 1866 #if defined(SSH_TUN_FILTER) 1867 if (options.tun_open == SSH_TUNMODE_POINTOPOINT) 1868 channel_register_filter(ssh, c->self, sys_tun_infilter, 1869 sys_tun_outfilter, NULL, NULL); 1870 #endif 1871 1872 if (cb != NULL) 1873 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1874 1875 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1876 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1877 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1878 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1879 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1880 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1881 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1882 (r = sshpkt_send(ssh)) != 0) 1883 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1884 1885 return ifname; 1886 } 1887 1888 /* XXXX move to generic input handler */ 1889 static int 1890 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1891 { 1892 Channel *c = NULL; 1893 char *ctype = NULL; 1894 int r; 1895 u_int rchan; 1896 size_t len; 1897 u_int rmaxpack, rwindow; 1898 1899 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1900 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1901 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1902 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1903 goto out; 1904 1905 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1906 ctype, rchan, rwindow, rmaxpack); 1907 1908 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1909 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1910 rmaxpack); 1911 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1912 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1913 } else if (strcmp(ctype, "x11") == 0) { 1914 c = client_request_x11(ssh, ctype, rchan); 1915 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1916 c = client_request_agent(ssh, ctype, rchan); 1917 } 1918 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1919 debug3("proxied to downstream: %s", ctype); 1920 } else if (c != NULL) { 1921 debug("confirm %s", ctype); 1922 c->remote_id = rchan; 1923 c->have_remote_id = 1; 1924 c->remote_window = rwindow; 1925 c->remote_maxpacket = rmaxpack; 1926 if (c->type != SSH_CHANNEL_CONNECTING) { 1927 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1928 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1929 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1930 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1931 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1932 (r = sshpkt_send(ssh)) != 0) 1933 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1934 } 1935 } else { 1936 debug("failure %s", ctype); 1937 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1938 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1939 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1940 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1941 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1942 (r = sshpkt_send(ssh)) != 0) 1943 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1944 } 1945 r = 0; 1946 out: 1947 free(ctype); 1948 return r; 1949 } 1950 1951 static int 1952 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1953 { 1954 Channel *c = NULL; 1955 char *rtype = NULL; 1956 u_char reply; 1957 u_int id, exitval; 1958 int r, success = 0; 1959 1960 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1961 return r; 1962 if (id <= INT_MAX) 1963 c = channel_lookup(ssh, id); 1964 if (channel_proxy_upstream(c, type, seq, ssh)) 1965 return 0; 1966 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1967 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1968 goto out; 1969 1970 debug("client_input_channel_req: channel %u rtype %s reply %d", 1971 id, rtype, reply); 1972 1973 if (c == NULL) { 1974 error("client_input_channel_req: channel %d: " 1975 "unknown channel", id); 1976 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 1977 if ((r = sshpkt_get_end(ssh)) != 0) 1978 goto out; 1979 chan_rcvd_eow(ssh, c); 1980 } else if (strcmp(rtype, "exit-status") == 0) { 1981 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 1982 goto out; 1983 if (c->ctl_chan != -1) { 1984 mux_exit_message(ssh, c, exitval); 1985 success = 1; 1986 } else if ((int)id == session_ident) { 1987 /* Record exit value of local session */ 1988 success = 1; 1989 exit_status = exitval; 1990 } else { 1991 /* Probably for a mux channel that has already closed */ 1992 debug_f("no sink for exit-status on channel %d", 1993 id); 1994 } 1995 if ((r = sshpkt_get_end(ssh)) != 0) 1996 goto out; 1997 } 1998 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 1999 if (!c->have_remote_id) 2000 fatal_f("channel %d: no remote_id", c->self); 2001 if ((r = sshpkt_start(ssh, success ? 2002 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2003 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2004 (r = sshpkt_send(ssh)) != 0) 2005 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2006 } 2007 r = 0; 2008 out: 2009 free(rtype); 2010 return r; 2011 } 2012 2013 struct hostkeys_update_ctx { 2014 /* The hostname and (optionally) IP address string for the server */ 2015 char *host_str, *ip_str; 2016 2017 /* 2018 * Keys received from the server and a flag for each indicating 2019 * whether they already exist in known_hosts. 2020 * keys_match is filled in by hostkeys_find() and later (for new 2021 * keys) by client_global_hostkeys_prove_confirm(). 2022 */ 2023 struct sshkey **keys; 2024 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2025 int *keys_verified; /* flag for new keys verified by server */ 2026 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2027 2028 /* 2029 * Keys that are in known_hosts, but were not present in the update 2030 * from the server (i.e. scheduled to be deleted). 2031 * Filled in by hostkeys_find(). 2032 */ 2033 struct sshkey **old_keys; 2034 size_t nold; 2035 2036 /* Various special cases. */ 2037 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2038 int ca_available; /* saw CA key for this host */ 2039 int old_key_seen; /* saw old key with other name/addr */ 2040 int other_name_seen; /* saw key with other name/addr */ 2041 }; 2042 2043 static void 2044 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2045 { 2046 size_t i; 2047 2048 if (ctx == NULL) 2049 return; 2050 for (i = 0; i < ctx->nkeys; i++) 2051 sshkey_free(ctx->keys[i]); 2052 free(ctx->keys); 2053 free(ctx->keys_match); 2054 free(ctx->keys_verified); 2055 for (i = 0; i < ctx->nold; i++) 2056 sshkey_free(ctx->old_keys[i]); 2057 free(ctx->old_keys); 2058 free(ctx->host_str); 2059 free(ctx->ip_str); 2060 free(ctx); 2061 } 2062 2063 /* 2064 * Returns non-zero if a known_hosts hostname list is not of a form that 2065 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2066 * hostnames lists that do not follow the form host[,ip]. 2067 */ 2068 static int 2069 hostspec_is_complex(const char *hosts) 2070 { 2071 char *cp; 2072 2073 /* wildcard */ 2074 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2075 return 1; 2076 /* single host/ip = ok */ 2077 if ((cp = strchr(hosts, ',')) == NULL) 2078 return 0; 2079 /* more than two entries on the line */ 2080 if (strchr(cp + 1, ',') != NULL) 2081 return 1; 2082 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2083 return 0; 2084 } 2085 2086 /* callback to search for ctx->keys in known_hosts */ 2087 static int 2088 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2089 { 2090 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2091 size_t i; 2092 struct sshkey **tmp; 2093 2094 if (l->key == NULL) 2095 return 0; 2096 if (l->status != HKF_STATUS_MATCHED) { 2097 /* Record if one of the keys appears on a non-matching line */ 2098 for (i = 0; i < ctx->nkeys; i++) { 2099 if (sshkey_equal(l->key, ctx->keys[i])) { 2100 ctx->other_name_seen = 1; 2101 debug3_f("found %s key under different " 2102 "name/addr at %s:%ld", 2103 sshkey_ssh_name(ctx->keys[i]), 2104 l->path, l->linenum); 2105 return 0; 2106 } 2107 } 2108 return 0; 2109 } 2110 /* Don't proceed if revocation or CA markers are present */ 2111 /* XXX relax this */ 2112 if (l->marker != MRK_NONE) { 2113 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2114 l->path, l->linenum); 2115 ctx->complex_hostspec = 1; 2116 return 0; 2117 } 2118 2119 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2120 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2121 if ((l->match & HKF_MATCH_HOST) == 0) { 2122 /* Record if address matched a different hostname. */ 2123 ctx->other_name_seen = 1; 2124 debug3_f("found address %s against different hostname " 2125 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2126 return 0; 2127 } else if ((l->match & HKF_MATCH_IP) == 0) { 2128 /* Record if hostname matched a different address. */ 2129 ctx->other_name_seen = 1; 2130 debug3_f("found hostname %s against different address " 2131 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2132 } 2133 } 2134 2135 /* 2136 * UpdateHostkeys is skipped for wildcard host names and hostnames 2137 * that contain more than two entries (ssh never writes these). 2138 */ 2139 if (hostspec_is_complex(l->hosts)) { 2140 debug3_f("hostkeys file %s:%ld complex host specification", 2141 l->path, l->linenum); 2142 ctx->complex_hostspec = 1; 2143 return 0; 2144 } 2145 2146 /* Mark off keys we've already seen for this host */ 2147 for (i = 0; i < ctx->nkeys; i++) { 2148 if (!sshkey_equal(l->key, ctx->keys[i])) 2149 continue; 2150 debug3_f("found %s key at %s:%ld", 2151 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2152 ctx->keys_match[i] |= l->match; 2153 return 0; 2154 } 2155 /* This line contained a key that not offered by the server */ 2156 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2157 l->path, l->linenum); 2158 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2159 sizeof(*ctx->old_keys))) == NULL) 2160 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2161 ctx->old_keys = tmp; 2162 ctx->old_keys[ctx->nold++] = l->key; 2163 l->key = NULL; 2164 2165 return 0; 2166 } 2167 2168 /* callback to search for ctx->old_keys in known_hosts under other names */ 2169 static int 2170 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2171 { 2172 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2173 size_t i; 2174 int hashed; 2175 2176 /* only care about lines that *don't* match the active host spec */ 2177 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2178 return 0; 2179 2180 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2181 for (i = 0; i < ctx->nold; i++) { 2182 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2183 continue; 2184 debug3_f("found deprecated %s key at %s:%ld as %s", 2185 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2186 hashed ? "[HASHED]" : l->hosts); 2187 ctx->old_key_seen = 1; 2188 break; 2189 } 2190 return 0; 2191 } 2192 2193 /* 2194 * Check known_hosts files for deprecated keys under other names. Returns 0 2195 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2196 * exist under names other than the active hostname/IP. 2197 */ 2198 static int 2199 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2200 { 2201 size_t i; 2202 int r; 2203 2204 debug2_f("checking for %zu deprecated keys", ctx->nold); 2205 for (i = 0; i < options.num_user_hostfiles; i++) { 2206 debug3_f("searching %s for %s / %s", 2207 options.user_hostfiles[i], ctx->host_str, 2208 ctx->ip_str ? ctx->ip_str : "(none)"); 2209 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2210 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2211 HKF_WANT_PARSE_KEY, 0)) != 0) { 2212 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2213 debug_f("hostkeys file %s does not exist", 2214 options.user_hostfiles[i]); 2215 continue; 2216 } 2217 error_fr(r, "hostkeys_foreach failed for %s", 2218 options.user_hostfiles[i]); 2219 return -1; 2220 } 2221 } 2222 return 0; 2223 } 2224 2225 static void 2226 hostkey_change_preamble(LogLevel loglevel) 2227 { 2228 do_log2(loglevel, "The server has updated its host keys."); 2229 do_log2(loglevel, "These changes were verified by the server's " 2230 "existing trusted key."); 2231 } 2232 2233 static void 2234 update_known_hosts(struct hostkeys_update_ctx *ctx) 2235 { 2236 int r, was_raw = 0, first = 1; 2237 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2238 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2239 char *fp, *response; 2240 size_t i; 2241 struct stat sb; 2242 2243 for (i = 0; i < ctx->nkeys; i++) { 2244 if (!ctx->keys_verified[i]) 2245 continue; 2246 if ((fp = sshkey_fingerprint(ctx->keys[i], 2247 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2248 fatal_f("sshkey_fingerprint failed"); 2249 if (first && asking) 2250 hostkey_change_preamble(loglevel); 2251 do_log2(loglevel, "Learned new hostkey: %s %s", 2252 sshkey_type(ctx->keys[i]), fp); 2253 first = 0; 2254 free(fp); 2255 } 2256 for (i = 0; i < ctx->nold; i++) { 2257 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2258 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2259 fatal_f("sshkey_fingerprint failed"); 2260 if (first && asking) 2261 hostkey_change_preamble(loglevel); 2262 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2263 sshkey_type(ctx->old_keys[i]), fp); 2264 first = 0; 2265 free(fp); 2266 } 2267 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2268 if (get_saved_tio() != NULL) { 2269 leave_raw_mode(1); 2270 was_raw = 1; 2271 } 2272 response = NULL; 2273 for (i = 0; !quit_pending && i < 3; i++) { 2274 free(response); 2275 response = read_passphrase("Accept updated hostkeys? " 2276 "(yes/no): ", RP_ECHO); 2277 if (response != NULL && strcasecmp(response, "yes") == 0) 2278 break; 2279 else if (quit_pending || response == NULL || 2280 strcasecmp(response, "no") == 0) { 2281 options.update_hostkeys = 0; 2282 break; 2283 } else { 2284 do_log2(loglevel, "Please enter " 2285 "\"yes\" or \"no\""); 2286 } 2287 } 2288 if (quit_pending || i >= 3 || response == NULL) 2289 options.update_hostkeys = 0; 2290 free(response); 2291 if (was_raw) 2292 enter_raw_mode(1); 2293 } 2294 if (options.update_hostkeys == 0) 2295 return; 2296 /* 2297 * Now that all the keys are verified, we can go ahead and replace 2298 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2299 * cancel the operation). 2300 */ 2301 for (i = 0; i < options.num_user_hostfiles; i++) { 2302 /* 2303 * NB. keys are only added to hostfiles[0], for the rest we 2304 * just delete the hostname entries. 2305 */ 2306 if (stat(options.user_hostfiles[i], &sb) != 0) { 2307 if (errno == ENOENT) { 2308 debug_f("known hosts file %s does not " 2309 "exist", options.user_hostfiles[i]); 2310 } else { 2311 error_f("known hosts file %s " 2312 "inaccessible: %s", 2313 options.user_hostfiles[i], strerror(errno)); 2314 } 2315 continue; 2316 } 2317 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2318 ctx->host_str, ctx->ip_str, 2319 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2320 options.hash_known_hosts, 0, 2321 options.fingerprint_hash)) != 0) { 2322 error_fr(r, "hostfile_replace_entries failed for %s", 2323 options.user_hostfiles[i]); 2324 } 2325 } 2326 } 2327 2328 static void 2329 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2330 u_int32_t seq, void *_ctx) 2331 { 2332 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2333 size_t i, ndone; 2334 struct sshbuf *signdata; 2335 int r, plaintype; 2336 const u_char *sig; 2337 const char *rsa_kexalg = NULL; 2338 char *alg = NULL; 2339 size_t siglen; 2340 2341 if (ctx->nnew == 0) 2342 fatal_f("ctx->nnew == 0"); /* sanity */ 2343 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2344 error("Server failed to confirm ownership of " 2345 "private host keys"); 2346 hostkeys_update_ctx_free(ctx); 2347 return; 2348 } 2349 if (sshkey_type_plain(sshkey_type_from_name( 2350 ssh->kex->hostkey_alg)) == KEY_RSA) 2351 rsa_kexalg = ssh->kex->hostkey_alg; 2352 if ((signdata = sshbuf_new()) == NULL) 2353 fatal_f("sshbuf_new failed"); 2354 /* 2355 * Expect a signature for each of the ctx->nnew private keys we 2356 * haven't seen before. They will be in the same order as the 2357 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2358 */ 2359 for (ndone = i = 0; i < ctx->nkeys; i++) { 2360 if (ctx->keys_match[i]) 2361 continue; 2362 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2363 /* Prepare data to be signed: session ID, unique string, key */ 2364 sshbuf_reset(signdata); 2365 if ( (r = sshbuf_put_cstring(signdata, 2366 "hostkeys-prove-00@openssh.com")) != 0 || 2367 (r = sshbuf_put_stringb(signdata, 2368 ssh->kex->session_id)) != 0 || 2369 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2370 fatal_fr(r, "compose signdata"); 2371 /* Extract and verify signature */ 2372 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2373 error_fr(r, "parse sig"); 2374 goto out; 2375 } 2376 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2377 error_fr(r, "server gave unintelligible signature " 2378 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2379 goto out; 2380 } 2381 /* 2382 * Special case for RSA keys: if a RSA hostkey was negotiated, 2383 * then use its signature type for verification of RSA hostkey 2384 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2385 */ 2386 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2387 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2388 debug_f("server used untrusted RSA signature algorithm " 2389 "%s for key %zu, disregarding", alg, i); 2390 free(alg); 2391 /* zap the key from the list */ 2392 sshkey_free(ctx->keys[i]); 2393 ctx->keys[i] = NULL; 2394 ndone++; 2395 continue; 2396 } 2397 debug3_f("verify %s key %zu using sigalg %s", 2398 sshkey_type(ctx->keys[i]), i, alg); 2399 free(alg); 2400 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2401 sshbuf_ptr(signdata), sshbuf_len(signdata), 2402 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2403 error_fr(r, "server gave bad signature for %s key %zu", 2404 sshkey_type(ctx->keys[i]), i); 2405 goto out; 2406 } 2407 /* Key is good. Mark it as 'seen' */ 2408 ctx->keys_verified[i] = 1; 2409 ndone++; 2410 } 2411 /* Shouldn't happen */ 2412 if (ndone != ctx->nnew) 2413 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2414 if ((r = sshpkt_get_end(ssh)) != 0) { 2415 error_f("protocol error"); 2416 goto out; 2417 } 2418 2419 /* Make the edits to known_hosts */ 2420 update_known_hosts(ctx); 2421 out: 2422 hostkeys_update_ctx_free(ctx); 2423 hostkeys_update_complete = 1; 2424 client_repledge(); 2425 } 2426 2427 /* 2428 * Handle hostkeys-00@openssh.com global request to inform the client of all 2429 * the server's hostkeys. The keys are checked against the user's 2430 * HostkeyAlgorithms preference before they are accepted. 2431 */ 2432 static int 2433 client_input_hostkeys(struct ssh *ssh) 2434 { 2435 const u_char *blob = NULL; 2436 size_t i, len = 0; 2437 struct sshbuf *buf = NULL; 2438 struct sshkey *key = NULL, **tmp; 2439 int r, prove_sent = 0; 2440 char *fp; 2441 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2442 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2443 struct hostkeys_update_ctx *ctx = NULL; 2444 u_int want; 2445 2446 if (hostkeys_seen) 2447 fatal_f("server already sent hostkeys"); 2448 if (!can_update_hostkeys()) 2449 return 1; 2450 hostkeys_seen = 1; 2451 2452 ctx = xcalloc(1, sizeof(*ctx)); 2453 while (ssh_packet_remaining(ssh) > 0) { 2454 sshkey_free(key); 2455 key = NULL; 2456 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2457 error_fr(r, "parse key"); 2458 goto out; 2459 } 2460 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2461 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2462 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2463 "convert key"); 2464 continue; 2465 } 2466 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2467 SSH_FP_DEFAULT); 2468 debug3_f("received %s key %s", sshkey_type(key), fp); 2469 free(fp); 2470 2471 if (!hostkey_accepted_by_hostkeyalgs(key)) { 2472 debug3_f("%s key not permitted by " 2473 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2474 continue; 2475 } 2476 /* Skip certs */ 2477 if (sshkey_is_cert(key)) { 2478 debug3_f("%s key is a certificate; skipping", 2479 sshkey_ssh_name(key)); 2480 continue; 2481 } 2482 /* Ensure keys are unique */ 2483 for (i = 0; i < ctx->nkeys; i++) { 2484 if (sshkey_equal(key, ctx->keys[i])) { 2485 error_f("received duplicated %s host key", 2486 sshkey_ssh_name(key)); 2487 goto out; 2488 } 2489 } 2490 /* Key is good, record it */ 2491 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2492 sizeof(*ctx->keys))) == NULL) 2493 fatal_f("recallocarray failed nkeys = %zu", 2494 ctx->nkeys); 2495 ctx->keys = tmp; 2496 ctx->keys[ctx->nkeys++] = key; 2497 key = NULL; 2498 } 2499 2500 if (ctx->nkeys == 0) { 2501 debug_f("server sent no hostkeys"); 2502 goto out; 2503 } 2504 2505 if ((ctx->keys_match = calloc(ctx->nkeys, 2506 sizeof(*ctx->keys_match))) == NULL || 2507 (ctx->keys_verified = calloc(ctx->nkeys, 2508 sizeof(*ctx->keys_verified))) == NULL) 2509 fatal_f("calloc failed"); 2510 2511 get_hostfile_hostname_ipaddr(host, 2512 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2513 options.port, &ctx->host_str, 2514 options.check_host_ip ? &ctx->ip_str : NULL); 2515 2516 /* Find which keys we already know about. */ 2517 for (i = 0; i < options.num_user_hostfiles; i++) { 2518 debug_f("searching %s for %s / %s", 2519 options.user_hostfiles[i], ctx->host_str, 2520 ctx->ip_str ? ctx->ip_str : "(none)"); 2521 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2522 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2523 HKF_WANT_PARSE_KEY, 0)) != 0) { 2524 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2525 debug_f("hostkeys file %s does not exist", 2526 options.user_hostfiles[i]); 2527 continue; 2528 } 2529 error_fr(r, "hostkeys_foreach failed for %s", 2530 options.user_hostfiles[i]); 2531 goto out; 2532 } 2533 } 2534 2535 /* Figure out if we have any new keys to add */ 2536 ctx->nnew = ctx->nincomplete = 0; 2537 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2538 for (i = 0; i < ctx->nkeys; i++) { 2539 if (ctx->keys_match[i] == 0) 2540 ctx->nnew++; 2541 if ((ctx->keys_match[i] & want) != want) 2542 ctx->nincomplete++; 2543 } 2544 2545 debug3_f("%zu server keys: %zu new, %zu retained, " 2546 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2547 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2548 ctx->nincomplete, ctx->nold); 2549 2550 if (ctx->nnew == 0 && ctx->nold == 0) { 2551 debug_f("no new or deprecated keys from server"); 2552 goto out; 2553 } 2554 2555 /* Various reasons why we cannot proceed with the update */ 2556 if (ctx->complex_hostspec) { 2557 debug_f("CA/revocation marker, manual host list or wildcard " 2558 "host pattern found, skipping UserKnownHostsFile update"); 2559 goto out; 2560 } 2561 if (ctx->other_name_seen) { 2562 debug_f("host key found matching a different name/address, " 2563 "skipping UserKnownHostsFile update"); 2564 goto out; 2565 } 2566 /* 2567 * If removing keys, check whether they appear under different 2568 * names/addresses and refuse to proceed if they do. This avoids 2569 * cases such as hosts with multiple names becoming inconsistent 2570 * with regards to CheckHostIP entries. 2571 * XXX UpdateHostkeys=force to override this (and other) checks? 2572 */ 2573 if (ctx->nold != 0) { 2574 if (check_old_keys_othernames(ctx) != 0) 2575 goto out; /* error already logged */ 2576 if (ctx->old_key_seen) { 2577 debug_f("key(s) for %s%s%s exist under other names; " 2578 "skipping UserKnownHostsFile update", 2579 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2580 ctx->ip_str == NULL ? "" : ctx->ip_str); 2581 goto out; 2582 } 2583 } 2584 2585 if (ctx->nnew == 0) { 2586 /* 2587 * We have some keys to remove or fix matching for. 2588 * We can proceed to do this without requiring a fresh proof 2589 * from the server. 2590 */ 2591 update_known_hosts(ctx); 2592 goto out; 2593 } 2594 /* 2595 * We have received previously-unseen keys from the server. 2596 * Ask the server to confirm ownership of the private halves. 2597 */ 2598 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2599 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2600 (r = sshpkt_put_cstring(ssh, 2601 "hostkeys-prove-00@openssh.com")) != 0 || 2602 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2603 fatal_fr(r, "prepare hostkeys-prove"); 2604 if ((buf = sshbuf_new()) == NULL) 2605 fatal_f("sshbuf_new"); 2606 for (i = 0; i < ctx->nkeys; i++) { 2607 if (ctx->keys_match[i]) 2608 continue; 2609 sshbuf_reset(buf); 2610 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2611 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2612 fatal_fr(r, "assemble hostkeys-prove"); 2613 } 2614 if ((r = sshpkt_send(ssh)) != 0) 2615 fatal_fr(r, "send hostkeys-prove"); 2616 client_register_global_confirm( 2617 client_global_hostkeys_prove_confirm, ctx); 2618 ctx = NULL; /* will be freed in callback */ 2619 prove_sent = 1; 2620 2621 /* Success */ 2622 out: 2623 hostkeys_update_ctx_free(ctx); 2624 sshkey_free(key); 2625 sshbuf_free(buf); 2626 if (!prove_sent) { 2627 /* UpdateHostkeys handling completed */ 2628 hostkeys_update_complete = 1; 2629 client_repledge(); 2630 } 2631 /* 2632 * NB. Return success for all cases. The server doesn't need to know 2633 * what the client does with its hosts file. 2634 */ 2635 return 1; 2636 } 2637 2638 static int 2639 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2640 { 2641 char *rtype; 2642 u_char want_reply; 2643 int r, success = 0; 2644 2645 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2646 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2647 goto out; 2648 debug("client_input_global_request: rtype %s want_reply %d", 2649 rtype, want_reply); 2650 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2651 success = client_input_hostkeys(ssh); 2652 if (want_reply) { 2653 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2654 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2655 (r = sshpkt_send(ssh)) != 0 || 2656 (r = ssh_packet_write_wait(ssh)) != 0) 2657 goto out; 2658 } 2659 r = 0; 2660 out: 2661 free(rtype); 2662 return r; 2663 } 2664 2665 static void 2666 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2667 { 2668 int r; 2669 2670 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2671 channel_request_start(ssh, id, "env", 0); 2672 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2673 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2674 (r = sshpkt_send(ssh)) != 0) 2675 fatal_fr(r, "send setenv"); 2676 } 2677 2678 void 2679 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2680 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2681 char **env) 2682 { 2683 size_t i, j, len; 2684 int matched, r; 2685 char *name, *val; 2686 Channel *c = NULL; 2687 2688 debug2_f("id %d", id); 2689 2690 if ((c = channel_lookup(ssh, id)) == NULL) 2691 fatal_f("channel %d: unknown channel", id); 2692 2693 ssh_packet_set_interactive(ssh, want_tty, 2694 options.ip_qos_interactive, options.ip_qos_bulk); 2695 2696 if (want_tty) { 2697 struct winsize ws; 2698 2699 /* Store window size in the packet. */ 2700 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2701 memset(&ws, 0, sizeof(ws)); 2702 2703 channel_request_start(ssh, id, "pty-req", 1); 2704 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2705 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2706 != 0 || 2707 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2708 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2709 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2710 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2711 fatal_fr(r, "build pty-req"); 2712 if (tiop == NULL) 2713 tiop = get_saved_tio(); 2714 ssh_tty_make_modes(ssh, -1, tiop); 2715 if ((r = sshpkt_send(ssh)) != 0) 2716 fatal_fr(r, "send pty-req"); 2717 /* XXX wait for reply */ 2718 c->client_tty = 1; 2719 } 2720 2721 /* Transfer any environment variables from client to server */ 2722 if (options.num_send_env != 0 && env != NULL) { 2723 debug("Sending environment."); 2724 for (i = 0; env[i] != NULL; i++) { 2725 /* Split */ 2726 name = xstrdup(env[i]); 2727 if ((val = strchr(name, '=')) == NULL) { 2728 free(name); 2729 continue; 2730 } 2731 *val++ = '\0'; 2732 2733 matched = 0; 2734 for (j = 0; j < options.num_send_env; j++) { 2735 if (match_pattern(name, options.send_env[j])) { 2736 matched = 1; 2737 break; 2738 } 2739 } 2740 if (!matched) { 2741 debug3("Ignored env %s", name); 2742 free(name); 2743 continue; 2744 } 2745 client_send_env(ssh, id, name, val); 2746 free(name); 2747 } 2748 } 2749 for (i = 0; i < options.num_setenv; i++) { 2750 /* Split */ 2751 name = xstrdup(options.setenv[i]); 2752 if ((val = strchr(name, '=')) == NULL) { 2753 free(name); 2754 continue; 2755 } 2756 *val++ = '\0'; 2757 client_send_env(ssh, id, name, val); 2758 free(name); 2759 } 2760 2761 len = sshbuf_len(cmd); 2762 if (len > 0) { 2763 if (len > 900) 2764 len = 900; 2765 if (want_subsystem) { 2766 debug("Sending subsystem: %.*s", 2767 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2768 channel_request_start(ssh, id, "subsystem", 1); 2769 client_expect_confirm(ssh, id, "subsystem", 2770 CONFIRM_CLOSE); 2771 } else { 2772 debug("Sending command: %.*s", 2773 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2774 channel_request_start(ssh, id, "exec", 1); 2775 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2776 } 2777 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2778 (r = sshpkt_send(ssh)) != 0) 2779 fatal_fr(r, "send command"); 2780 } else { 2781 channel_request_start(ssh, id, "shell", 1); 2782 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2783 if ((r = sshpkt_send(ssh)) != 0) 2784 fatal_fr(r, "send shell"); 2785 } 2786 2787 session_setup_complete = 1; 2788 client_repledge(); 2789 } 2790 2791 static void 2792 client_init_dispatch(struct ssh *ssh) 2793 { 2794 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2795 2796 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2797 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2798 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2799 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2800 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2801 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2802 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2803 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2804 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2805 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2806 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2807 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2808 2809 /* rekeying */ 2810 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2811 2812 /* global request reply messages */ 2813 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2814 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2815 } 2816 2817 void 2818 client_stop_mux(void) 2819 { 2820 if (options.control_path != NULL && muxserver_sock != -1) 2821 unlink(options.control_path); 2822 /* 2823 * If we are in persist mode, or don't have a shell, signal that we 2824 * should close when all active channels are closed. 2825 */ 2826 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2827 session_closed = 1; 2828 setproctitle("[stopped mux]"); 2829 } 2830 } 2831 2832 /* client specific fatal cleanup */ 2833 void 2834 cleanup_exit(int i) 2835 { 2836 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2837 if (options.control_path != NULL && muxserver_sock != -1) 2838 unlink(options.control_path); 2839 ssh_kill_proxy_command(); 2840 _exit(i); 2841 } 2842