1 /* $OpenBSD: clientloop.c,v 1.403 2024/02/21 05:57:34 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 struct sshbuf *stderr_buffer; /* Used for final exit message. */ 160 static int connection_in; /* Connection to server (input). */ 161 static int connection_out; /* Connection to server (output). */ 162 static int need_rekeying; /* Set to non-zero if rekeying is requested. */ 163 static int session_closed; /* In SSH2: login session closed. */ 164 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */ 165 static time_t server_alive_time; /* Time to do server_alive_check */ 166 static int hostkeys_update_complete; 167 static int session_setup_complete; 168 169 static void client_init_dispatch(struct ssh *ssh); 170 int session_ident = -1; 171 172 /* Track escape per proto2 channel */ 173 struct escape_filter_ctx { 174 int escape_pending; 175 int escape_char; 176 }; 177 178 /* Context for channel confirmation replies */ 179 struct channel_reply_ctx { 180 const char *request_type; 181 int id; 182 enum confirm_action action; 183 }; 184 185 /* Global request success/failure callbacks */ 186 /* XXX move to struct ssh? */ 187 struct global_confirm { 188 TAILQ_ENTRY(global_confirm) entry; 189 global_confirm_cb *cb; 190 void *ctx; 191 int ref_count; 192 }; 193 TAILQ_HEAD(global_confirms, global_confirm); 194 static struct global_confirms global_confirms = 195 TAILQ_HEAD_INITIALIZER(global_confirms); 196 197 void ssh_process_session2_setup(int, int, int, struct sshbuf *); 198 static void quit_message(const char *fmt, ...) 199 __attribute__((__format__ (printf, 1, 2))); 200 201 static void 202 quit_message(const char *fmt, ...) 203 { 204 char *msg; 205 va_list args; 206 int r; 207 208 va_start(args, fmt); 209 xvasprintf(&msg, fmt, args); 210 va_end(args); 211 212 if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0) 213 fatal_fr(r, "sshbuf_putf"); 214 free(msg); 215 quit_pending = 1; 216 } 217 218 /* 219 * Signal handler for the window change signal (SIGWINCH). This just sets a 220 * flag indicating that the window has changed. 221 */ 222 static void 223 window_change_handler(int sig) 224 { 225 received_window_change_signal = 1; 226 } 227 228 /* 229 * Signal handler for signals that cause the program to terminate. These 230 * signals must be trapped to restore terminal modes. 231 */ 232 static void 233 signal_handler(int sig) 234 { 235 received_signal = sig; 236 quit_pending = 1; 237 } 238 239 /* 240 * Sets control_persist_exit_time to the absolute time when the 241 * backgrounded control master should exit due to expiry of the 242 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded 243 * control master process, or if there is no ControlPersist timeout. 244 */ 245 static void 246 set_control_persist_exit_time(struct ssh *ssh) 247 { 248 if (muxserver_sock == -1 || !options.control_persist 249 || options.control_persist_timeout == 0) { 250 /* not using a ControlPersist timeout */ 251 control_persist_exit_time = 0; 252 } else if (channel_still_open(ssh)) { 253 /* some client connections are still open */ 254 if (control_persist_exit_time > 0) 255 debug2_f("cancel scheduled exit"); 256 control_persist_exit_time = 0; 257 } else if (control_persist_exit_time <= 0) { 258 /* a client connection has recently closed */ 259 control_persist_exit_time = monotime() + 260 (time_t)options.control_persist_timeout; 261 debug2_f("schedule exit in %d seconds", 262 options.control_persist_timeout); 263 } 264 /* else we are already counting down to the timeout */ 265 } 266 267 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_" 268 static int 269 client_x11_display_valid(const char *display) 270 { 271 size_t i, dlen; 272 273 if (display == NULL) 274 return 0; 275 276 dlen = strlen(display); 277 for (i = 0; i < dlen; i++) { 278 if (!isalnum((u_char)display[i]) && 279 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) { 280 debug("Invalid character '%c' in DISPLAY", display[i]); 281 return 0; 282 } 283 } 284 return 1; 285 } 286 287 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1" 288 #define X11_TIMEOUT_SLACK 60 289 int 290 client_x11_get_proto(struct ssh *ssh, const char *display, 291 const char *xauth_path, u_int trusted, u_int timeout, 292 char **_proto, char **_data) 293 { 294 char *cmd, line[512], xdisplay[512]; 295 char xauthfile[PATH_MAX], xauthdir[PATH_MAX]; 296 static char proto[512], data[512]; 297 FILE *f; 298 int got_data = 0, generated = 0, do_unlink = 0, r; 299 struct stat st; 300 u_int now, x11_timeout_real; 301 302 *_proto = proto; 303 *_data = data; 304 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0'; 305 306 if (!client_x11_display_valid(display)) { 307 if (display != NULL) 308 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding", 309 display); 310 return -1; 311 } 312 if (xauth_path != NULL && stat(xauth_path, &st) == -1) { 313 debug("No xauth program."); 314 xauth_path = NULL; 315 } 316 317 if (xauth_path != NULL) { 318 /* 319 * Handle FamilyLocal case where $DISPLAY does 320 * not match an authorization entry. For this we 321 * just try "xauth list unix:displaynum.screennum". 322 * XXX: "localhost" match to determine FamilyLocal 323 * is not perfect. 324 */ 325 if (strncmp(display, "localhost:", 10) == 0) { 326 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s", 327 display + 10)) < 0 || 328 (size_t)r >= sizeof(xdisplay)) { 329 error_f("display name too long"); 330 return -1; 331 } 332 display = xdisplay; 333 } 334 if (trusted == 0) { 335 /* 336 * Generate an untrusted X11 auth cookie. 337 * 338 * The authentication cookie should briefly outlive 339 * ssh's willingness to forward X11 connections to 340 * avoid nasty fail-open behaviour in the X server. 341 */ 342 mktemp_proto(xauthdir, sizeof(xauthdir)); 343 if (mkdtemp(xauthdir) == NULL) { 344 error_f("mkdtemp: %s", strerror(errno)); 345 return -1; 346 } 347 do_unlink = 1; 348 if ((r = snprintf(xauthfile, sizeof(xauthfile), 349 "%s/xauthfile", xauthdir)) < 0 || 350 (size_t)r >= sizeof(xauthfile)) { 351 error_f("xauthfile path too long"); 352 rmdir(xauthdir); 353 return -1; 354 } 355 356 if (timeout == 0) { 357 /* auth doesn't time out */ 358 xasprintf(&cmd, "%s -f %s generate %s %s " 359 "untrusted 2>%s", 360 xauth_path, xauthfile, display, 361 SSH_X11_PROTO, _PATH_DEVNULL); 362 } else { 363 /* Add some slack to requested expiry */ 364 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK) 365 x11_timeout_real = timeout + 366 X11_TIMEOUT_SLACK; 367 else { 368 /* Don't overflow on long timeouts */ 369 x11_timeout_real = UINT_MAX; 370 } 371 xasprintf(&cmd, "%s -f %s generate %s %s " 372 "untrusted timeout %u 2>%s", 373 xauth_path, xauthfile, display, 374 SSH_X11_PROTO, x11_timeout_real, 375 _PATH_DEVNULL); 376 } 377 debug2_f("xauth command: %s", cmd); 378 379 if (timeout != 0 && x11_refuse_time == 0) { 380 now = monotime() + 1; 381 if (SSH_TIME_T_MAX - timeout < now) 382 x11_refuse_time = SSH_TIME_T_MAX; 383 else 384 x11_refuse_time = now + timeout; 385 channel_set_x11_refuse_time(ssh, 386 x11_refuse_time); 387 } 388 if (system(cmd) == 0) 389 generated = 1; 390 free(cmd); 391 } 392 393 /* 394 * When in untrusted mode, we read the cookie only if it was 395 * successfully generated as an untrusted one in the step 396 * above. 397 */ 398 if (trusted || generated) { 399 xasprintf(&cmd, 400 "%s %s%s list %s 2>" _PATH_DEVNULL, 401 xauth_path, 402 generated ? "-f " : "" , 403 generated ? xauthfile : "", 404 display); 405 debug2("x11_get_proto: %s", cmd); 406 f = popen(cmd, "r"); 407 if (f && fgets(line, sizeof(line), f) && 408 sscanf(line, "%*s %511s %511s", proto, data) == 2) 409 got_data = 1; 410 if (f) 411 pclose(f); 412 free(cmd); 413 } 414 } 415 416 if (do_unlink) { 417 unlink(xauthfile); 418 rmdir(xauthdir); 419 } 420 421 /* Don't fall back to fake X11 data for untrusted forwarding */ 422 if (!trusted && !got_data) { 423 error("Warning: untrusted X11 forwarding setup failed: " 424 "xauth key data not generated"); 425 return -1; 426 } 427 428 /* 429 * If we didn't get authentication data, just make up some 430 * data. The forwarding code will check the validity of the 431 * response anyway, and substitute this data. The X11 432 * server, however, will ignore this fake data and use 433 * whatever authentication mechanisms it was using otherwise 434 * for the local connection. 435 */ 436 if (!got_data) { 437 u_int8_t rnd[16]; 438 u_int i; 439 440 logit("Warning: No xauth data; " 441 "using fake authentication data for X11 forwarding."); 442 strlcpy(proto, SSH_X11_PROTO, sizeof proto); 443 arc4random_buf(rnd, sizeof(rnd)); 444 for (i = 0; i < sizeof(rnd); i++) { 445 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", 446 rnd[i]); 447 } 448 } 449 450 return 0; 451 } 452 453 /* 454 * Checks if the client window has changed, and sends a packet about it to 455 * the server if so. The actual change is detected elsewhere (by a software 456 * interrupt on Unix); this just checks the flag and sends a message if 457 * appropriate. 458 */ 459 460 static void 461 client_check_window_change(struct ssh *ssh) 462 { 463 if (!received_window_change_signal) 464 return; 465 received_window_change_signal = 0; 466 debug2_f("changed"); 467 channel_send_window_changes(ssh); 468 } 469 470 static int 471 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh) 472 { 473 struct global_confirm *gc; 474 475 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL) 476 return 0; 477 if (gc->cb != NULL) 478 gc->cb(ssh, type, seq, gc->ctx); 479 if (--gc->ref_count <= 0) { 480 TAILQ_REMOVE(&global_confirms, gc, entry); 481 freezero(gc, sizeof(*gc)); 482 } 483 484 ssh_packet_set_alive_timeouts(ssh, 0); 485 return 0; 486 } 487 488 static void 489 schedule_server_alive_check(void) 490 { 491 if (options.server_alive_interval > 0) 492 server_alive_time = monotime() + options.server_alive_interval; 493 } 494 495 static void 496 server_alive_check(struct ssh *ssh) 497 { 498 int r; 499 500 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) { 501 logit("Timeout, server %s not responding.", host); 502 cleanup_exit(255); 503 } 504 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 505 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 || 506 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */ 507 (r = sshpkt_send(ssh)) != 0) 508 fatal_fr(r, "send packet"); 509 /* Insert an empty placeholder to maintain ordering */ 510 client_register_global_confirm(NULL, NULL); 511 schedule_server_alive_check(); 512 } 513 514 /* Try to send a dummy keystroke */ 515 static int 516 send_chaff(struct ssh *ssh) 517 { 518 int r; 519 520 if (ssh->kex == NULL || (ssh->kex->flags & KEX_HAS_PING) == 0) 521 return 0; 522 /* XXX probabilistically send chaff? */ 523 /* 524 * a SSH2_MSG_CHANNEL_DATA payload is 9 bytes: 525 * 4 bytes channel ID + 4 bytes string length + 1 byte string data 526 * simulate that here. 527 */ 528 if ((r = sshpkt_start(ssh, SSH2_MSG_PING)) != 0 || 529 (r = sshpkt_put_cstring(ssh, "PING!")) != 0 || 530 (r = sshpkt_send(ssh)) != 0) 531 fatal_fr(r, "send packet"); 532 return 1; 533 } 534 535 /* Sets the next interval to send a keystroke or chaff packet */ 536 static void 537 set_next_interval(const struct timespec *now, struct timespec *next_interval, 538 u_int interval_ms, int starting) 539 { 540 struct timespec tmp; 541 long long interval_ns, fuzz_ns; 542 static long long rate_fuzz; 543 544 interval_ns = interval_ms * (1000LL * 1000); 545 fuzz_ns = (interval_ns * SSH_KEYSTROKE_TIMING_FUZZ) / 100; 546 /* Center fuzz around requested interval */ 547 if (fuzz_ns > INT_MAX) 548 fuzz_ns = INT_MAX; 549 if (fuzz_ns > interval_ns) { 550 /* Shouldn't happen */ 551 fatal_f("internal error: fuzz %u%% %lldns > interval %lldns", 552 SSH_KEYSTROKE_TIMING_FUZZ, fuzz_ns, interval_ns); 553 } 554 /* 555 * Randomise the keystroke/chaff intervals in two ways: 556 * 1. Each interval has some random jitter applied to make the 557 * interval-to-interval time unpredictable. 558 * 2. The overall interval rate is also randomly perturbed for each 559 * chaffing session to make the average rate unpredictable. 560 */ 561 if (starting) 562 rate_fuzz = arc4random_uniform(fuzz_ns); 563 interval_ns -= fuzz_ns; 564 interval_ns += arc4random_uniform(fuzz_ns) + rate_fuzz; 565 566 tmp.tv_sec = interval_ns / (1000 * 1000 * 1000); 567 tmp.tv_nsec = interval_ns % (1000 * 1000 * 1000); 568 569 timespecadd(now, &tmp, next_interval); 570 } 571 572 /* 573 * Performs keystroke timing obfuscation. Returns non-zero if the 574 * output fd should be polled. 575 */ 576 static int 577 obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout, 578 int channel_did_enqueue) 579 { 580 static int active; 581 static struct timespec next_interval, chaff_until; 582 struct timespec now, tmp; 583 int just_started = 0, had_keystroke = 0; 584 static unsigned long long nchaff; 585 char *stop_reason = NULL; 586 long long n; 587 588 monotime_ts(&now); 589 590 if (options.obscure_keystroke_timing_interval <= 0) 591 return 1; /* disabled in config */ 592 593 if (!channel_tty_open(ssh) || quit_pending) { 594 /* Stop if no channels left of we're waiting for one to close */ 595 stop_reason = "no active channels"; 596 } else if (ssh_packet_is_rekeying(ssh)) { 597 /* Stop if we're rekeying */ 598 stop_reason = "rekeying started"; 599 } else if (!ssh_packet_interactive_data_to_write(ssh) && 600 ssh_packet_have_data_to_write(ssh)) { 601 /* Stop if the output buffer has more than a few keystrokes */ 602 stop_reason = "output buffer filling"; 603 } else if (active && channel_did_enqueue && 604 ssh_packet_have_data_to_write(ssh)) { 605 /* Still in active mode and have a keystroke queued. */ 606 had_keystroke = 1; 607 } else if (active) { 608 if (timespeccmp(&now, &chaff_until, >=)) { 609 /* Stop if there have been no keystrokes for a while */ 610 stop_reason = "chaff time expired"; 611 } else if (timespeccmp(&now, &next_interval, >=) && 612 !ssh_packet_have_data_to_write(ssh)) { 613 /* If due to send but have no data, then send chaff */ 614 if (send_chaff(ssh)) 615 nchaff++; 616 } 617 } 618 619 if (stop_reason != NULL) { 620 if (active) { 621 debug3_f("stopping: %s (%llu chaff packets sent)", 622 stop_reason, nchaff); 623 active = 0; 624 } 625 return 1; 626 } 627 628 /* 629 * If we're in interactive mode, and only have a small amount 630 * of outbound data, then we assume that the user is typing 631 * interactively. In this case, start quantising outbound packets to 632 * fixed time intervals to hide inter-keystroke timing. 633 */ 634 if (!active && ssh_packet_interactive_data_to_write(ssh) && 635 channel_did_enqueue && ssh_packet_have_data_to_write(ssh)) { 636 debug3_f("starting: interval ~%dms", 637 options.obscure_keystroke_timing_interval); 638 just_started = had_keystroke = active = 1; 639 nchaff = 0; 640 set_next_interval(&now, &next_interval, 641 options.obscure_keystroke_timing_interval, 1); 642 } 643 644 /* Don't hold off if obfuscation inactive */ 645 if (!active) 646 return 1; 647 648 if (had_keystroke) { 649 /* 650 * Arrange to send chaff packets for a random interval after 651 * the last keystroke was sent. 652 */ 653 ms_to_timespec(&tmp, SSH_KEYSTROKE_CHAFF_MIN_MS + 654 arc4random_uniform(SSH_KEYSTROKE_CHAFF_RNG_MS)); 655 timespecadd(&now, &tmp, &chaff_until); 656 } 657 658 ptimeout_deadline_monotime_tsp(timeout, &next_interval); 659 660 if (just_started) 661 return 1; 662 663 /* Don't arm output fd for poll until the timing interval has elapsed */ 664 if (timespeccmp(&now, &next_interval, <)) 665 return 0; 666 667 /* Calculate number of intervals missed since the last check */ 668 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000; 669 n += now.tv_nsec - next_interval.tv_nsec; 670 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000; 671 n = (n < 0) ? 1 : n + 1; 672 673 /* Advance to the next interval */ 674 set_next_interval(&now, &next_interval, 675 options.obscure_keystroke_timing_interval * n, 0); 676 return 1; 677 } 678 679 /* 680 * Waits until the client can do something (some data becomes available on 681 * one of the file descriptors). 682 */ 683 static void 684 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp, 685 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue, 686 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp) 687 { 688 struct timespec timeout; 689 int ret, oready; 690 u_int p; 691 692 *conn_in_readyp = *conn_out_readyp = 0; 693 694 /* Prepare channel poll. First two pollfd entries are reserved */ 695 ptimeout_init(&timeout); 696 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 697 if (*npfd_activep < 2) 698 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 699 700 /* channel_prepare_poll could have closed the last channel */ 701 if (session_closed && !channel_still_open(ssh) && 702 !ssh_packet_have_data_to_write(ssh)) { 703 /* clear events since we did not call poll() */ 704 for (p = 0; p < *npfd_activep; p++) 705 (*pfdp)[p].revents = 0; 706 return; 707 } 708 709 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue); 710 711 /* Monitor server connection on reserved pollfd entries */ 712 (*pfdp)[0].fd = connection_in; 713 (*pfdp)[0].events = POLLIN; 714 (*pfdp)[1].fd = connection_out; 715 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ? 716 POLLOUT : 0; 717 718 /* 719 * Wait for something to happen. This will suspend the process until 720 * some polled descriptor can be read, written, or has some other 721 * event pending, or a timeout expires. 722 */ 723 set_control_persist_exit_time(ssh); 724 if (control_persist_exit_time > 0) 725 ptimeout_deadline_monotime(&timeout, control_persist_exit_time); 726 if (options.server_alive_interval > 0) 727 ptimeout_deadline_monotime(&timeout, server_alive_time); 728 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 729 ptimeout_deadline_sec(&timeout, 730 ssh_packet_get_rekey_timeout(ssh)); 731 } 732 733 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp); 734 735 if (ret == -1) { 736 /* 737 * We have to clear the events because we return. 738 * We have to return, because the mainloop checks for the flags 739 * set by the signal handlers. 740 */ 741 for (p = 0; p < *npfd_activep; p++) 742 (*pfdp)[p].revents = 0; 743 if (errno == EINTR) 744 return; 745 /* Note: we might still have data in the buffers. */ 746 quit_message("poll: %s", strerror(errno)); 747 return; 748 } 749 750 *conn_in_readyp = (*pfdp)[0].revents != 0; 751 *conn_out_readyp = (*pfdp)[1].revents != 0; 752 753 if (options.server_alive_interval > 0 && !*conn_in_readyp && 754 monotime() >= server_alive_time) { 755 /* 756 * ServerAlive check is needed. We can't rely on the poll 757 * timing out since traffic on the client side such as port 758 * forwards can keep waking it up. 759 */ 760 server_alive_check(ssh); 761 } 762 } 763 764 static void 765 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr) 766 { 767 /* Flush stdout and stderr buffers. */ 768 if (sshbuf_len(bout) > 0) 769 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout), 770 sshbuf_len(bout)); 771 if (sshbuf_len(berr) > 0) 772 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr), 773 sshbuf_len(berr)); 774 775 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 776 777 sshbuf_reset(bin); 778 sshbuf_reset(bout); 779 sshbuf_reset(berr); 780 781 /* Send the suspend signal to the program itself. */ 782 kill(getpid(), SIGTSTP); 783 784 /* Reset window sizes in case they have changed */ 785 received_window_change_signal = 1; 786 787 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 788 } 789 790 static void 791 client_process_net_input(struct ssh *ssh) 792 { 793 int r; 794 795 /* 796 * Read input from the server, and add any such data to the buffer of 797 * the packet subsystem. 798 */ 799 schedule_server_alive_check(); 800 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 801 return; /* success */ 802 if (r == SSH_ERR_SYSTEM_ERROR) { 803 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK) 804 return; 805 if (errno == EPIPE) { 806 quit_message("Connection to %s closed by remote host.", 807 host); 808 return; 809 } 810 } 811 quit_message("Read from remote host %s: %s", host, ssh_err(r)); 812 } 813 814 static void 815 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) 816 { 817 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; 818 char errmsg[256]; 819 int r, tochan; 820 821 /* 822 * If a TTY was explicitly requested, then a failure to allocate 823 * one is fatal. 824 */ 825 if (cr->action == CONFIRM_TTY && 826 (options.request_tty == REQUEST_TTY_FORCE || 827 options.request_tty == REQUEST_TTY_YES)) 828 cr->action = CONFIRM_CLOSE; 829 830 /* XXX suppress on mux _client_ quietmode */ 831 tochan = options.log_level >= SYSLOG_LEVEL_ERROR && 832 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; 833 834 if (type == SSH2_MSG_CHANNEL_SUCCESS) { 835 debug2("%s request accepted on channel %d", 836 cr->request_type, c->self); 837 } else if (type == SSH2_MSG_CHANNEL_FAILURE) { 838 if (tochan) { 839 snprintf(errmsg, sizeof(errmsg), 840 "%s request failed\r\n", cr->request_type); 841 } else { 842 snprintf(errmsg, sizeof(errmsg), 843 "%s request failed on channel %d", 844 cr->request_type, c->self); 845 } 846 /* If error occurred on primary session channel, then exit */ 847 if (cr->action == CONFIRM_CLOSE && c->self == session_ident) 848 fatal("%s", errmsg); 849 /* 850 * If error occurred on mux client, append to 851 * their stderr. 852 */ 853 if (tochan) { 854 debug3_f("channel %d: mux request: %s", c->self, 855 cr->request_type); 856 if ((r = sshbuf_put(c->extended, errmsg, 857 strlen(errmsg))) != 0) 858 fatal_fr(r, "sshbuf_put"); 859 } else 860 error("%s", errmsg); 861 if (cr->action == CONFIRM_TTY) { 862 /* 863 * If a TTY allocation error occurred, then arrange 864 * for the correct TTY to leave raw mode. 865 */ 866 if (c->self == session_ident) 867 leave_raw_mode(0); 868 else 869 mux_tty_alloc_failed(ssh, c); 870 } else if (cr->action == CONFIRM_CLOSE) { 871 chan_read_failed(ssh, c); 872 chan_write_failed(ssh, c); 873 } 874 } 875 free(cr); 876 } 877 878 static void 879 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) 880 { 881 free(ctx); 882 } 883 884 void 885 client_expect_confirm(struct ssh *ssh, int id, const char *request, 886 enum confirm_action action) 887 { 888 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); 889 890 cr->request_type = request; 891 cr->action = action; 892 893 channel_register_status_confirm(ssh, id, client_status_confirm, 894 client_abandon_status_confirm, cr); 895 } 896 897 void 898 client_register_global_confirm(global_confirm_cb *cb, void *ctx) 899 { 900 struct global_confirm *gc, *last_gc; 901 902 /* Coalesce identical callbacks */ 903 last_gc = TAILQ_LAST(&global_confirms, global_confirms); 904 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { 905 if (++last_gc->ref_count >= INT_MAX) 906 fatal_f("last_gc->ref_count = %d", 907 last_gc->ref_count); 908 return; 909 } 910 911 gc = xcalloc(1, sizeof(*gc)); 912 gc->cb = cb; 913 gc->ctx = ctx; 914 gc->ref_count = 1; 915 TAILQ_INSERT_TAIL(&global_confirms, gc, entry); 916 } 917 918 /* 919 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com 920 * hostkey update request. 921 */ 922 static int 923 can_update_hostkeys(void) 924 { 925 if (hostkeys_update_complete) 926 return 0; 927 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && 928 options.batch_mode) 929 return 0; /* won't ask in batchmode, so don't even try */ 930 if (!options.update_hostkeys || options.num_user_hostfiles <= 0) 931 return 0; 932 return 1; 933 } 934 935 static void 936 client_repledge(void) 937 { 938 debug3_f("enter"); 939 940 /* Might be able to tighten pledge now that session is established */ 941 if (options.control_master || options.control_path != NULL || 942 options.forward_x11 || options.fork_after_authentication || 943 can_update_hostkeys() || 944 (session_ident != -1 && !session_setup_complete)) { 945 /* Can't tighten */ 946 return; 947 } 948 /* 949 * LocalCommand and UpdateHostkeys have finished, so can get rid of 950 * filesystem. 951 * 952 * XXX protocol allows a server can to change hostkeys during the 953 * connection at rekey time that could trigger a hostkeys update 954 * but AFAIK no implementations support this. Could improve by 955 * forcing known_hosts to be read-only or via unveil(2). 956 */ 957 if (options.num_local_forwards != 0 || 958 options.num_remote_forwards != 0 || 959 options.num_permitted_remote_opens != 0 || 960 options.enable_escape_commandline != 0) { 961 /* rfwd needs inet */ 962 debug("pledge: network"); 963 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 964 fatal_f("pledge(): %s", strerror(errno)); 965 } else if (options.forward_agent != 0) { 966 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */ 967 debug("pledge: agent"); 968 if (pledge("stdio unix proc tty", NULL) == -1) 969 fatal_f("pledge(): %s", strerror(errno)); 970 } else { 971 debug("pledge: fork"); 972 if (pledge("stdio proc tty", NULL) == -1) 973 fatal_f("pledge(): %s", strerror(errno)); 974 } 975 /* XXX further things to do: 976 * 977 * - might be able to get rid of proc if we kill ~^Z 978 * - ssh -N (no session) 979 * - stdio forwarding 980 * - sessions without tty 981 */ 982 } 983 984 static void 985 process_cmdline(struct ssh *ssh) 986 { 987 void (*handler)(int); 988 char *s, *cmd; 989 int ok, delete = 0, local = 0, remote = 0, dynamic = 0; 990 struct Forward fwd; 991 992 memset(&fwd, 0, sizeof(fwd)); 993 994 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 995 handler = ssh_signal(SIGINT, SIG_IGN); 996 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); 997 if (s == NULL) 998 goto out; 999 while (isspace((u_char)*s)) 1000 s++; 1001 if (*s == '-') 1002 s++; /* Skip cmdline '-', if any */ 1003 if (*s == '\0') 1004 goto out; 1005 1006 if (*s == 'h' || *s == 'H' || *s == '?') { 1007 logit("Commands:"); 1008 logit(" -L[bind_address:]port:host:hostport " 1009 "Request local forward"); 1010 logit(" -R[bind_address:]port:host:hostport " 1011 "Request remote forward"); 1012 logit(" -D[bind_address:]port " 1013 "Request dynamic forward"); 1014 logit(" -KL[bind_address:]port " 1015 "Cancel local forward"); 1016 logit(" -KR[bind_address:]port " 1017 "Cancel remote forward"); 1018 logit(" -KD[bind_address:]port " 1019 "Cancel dynamic forward"); 1020 if (!options.permit_local_command) 1021 goto out; 1022 logit(" !args " 1023 "Execute local command"); 1024 goto out; 1025 } 1026 1027 if (*s == '!' && options.permit_local_command) { 1028 s++; 1029 ssh_local_cmd(s); 1030 goto out; 1031 } 1032 1033 if (*s == 'K') { 1034 delete = 1; 1035 s++; 1036 } 1037 if (*s == 'L') 1038 local = 1; 1039 else if (*s == 'R') 1040 remote = 1; 1041 else if (*s == 'D') 1042 dynamic = 1; 1043 else { 1044 logit("Invalid command."); 1045 goto out; 1046 } 1047 1048 while (isspace((u_char)*++s)) 1049 ; 1050 1051 /* XXX update list of forwards in options */ 1052 if (delete) { 1053 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ 1054 if (!parse_forward(&fwd, s, 1, 0)) { 1055 logit("Bad forwarding close specification."); 1056 goto out; 1057 } 1058 if (remote) 1059 ok = channel_request_rforward_cancel(ssh, &fwd) == 0; 1060 else if (dynamic) 1061 ok = channel_cancel_lport_listener(ssh, &fwd, 1062 0, &options.fwd_opts) > 0; 1063 else 1064 ok = channel_cancel_lport_listener(ssh, &fwd, 1065 CHANNEL_CANCEL_PORT_STATIC, 1066 &options.fwd_opts) > 0; 1067 if (!ok) { 1068 logit("Unknown port forwarding."); 1069 goto out; 1070 } 1071 logit("Canceled forwarding."); 1072 } else { 1073 /* -R specs can be both dynamic or not, so check both. */ 1074 if (remote) { 1075 if (!parse_forward(&fwd, s, 0, remote) && 1076 !parse_forward(&fwd, s, 1, remote)) { 1077 logit("Bad remote forwarding specification."); 1078 goto out; 1079 } 1080 } else if (!parse_forward(&fwd, s, dynamic, remote)) { 1081 logit("Bad local forwarding specification."); 1082 goto out; 1083 } 1084 if (local || dynamic) { 1085 if (!channel_setup_local_fwd_listener(ssh, &fwd, 1086 &options.fwd_opts)) { 1087 logit("Port forwarding failed."); 1088 goto out; 1089 } 1090 } else { 1091 if (channel_request_remote_forwarding(ssh, &fwd) < 0) { 1092 logit("Port forwarding failed."); 1093 goto out; 1094 } 1095 } 1096 logit("Forwarding port."); 1097 } 1098 1099 out: 1100 ssh_signal(SIGINT, handler); 1101 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1102 free(cmd); 1103 free(fwd.listen_host); 1104 free(fwd.listen_path); 1105 free(fwd.connect_host); 1106 free(fwd.connect_path); 1107 } 1108 1109 /* reasons to suppress output of an escape command in help output */ 1110 #define SUPPRESS_NEVER 0 /* never suppress, always show */ 1111 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ 1112 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ 1113 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ 1114 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/ 1115 struct escape_help_text { 1116 const char *cmd; 1117 const char *text; 1118 unsigned int flags; 1119 }; 1120 static struct escape_help_text esc_txt[] = { 1121 {".", "terminate session", SUPPRESS_MUXMASTER}, 1122 {".", "terminate connection (and any multiplexed sessions)", 1123 SUPPRESS_MUXCLIENT}, 1124 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, 1125 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE}, 1126 {"R", "request rekey", SUPPRESS_NEVER}, 1127 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, 1128 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, 1129 {"#", "list forwarded connections", SUPPRESS_NEVER}, 1130 {"&", "background ssh (when waiting for connections to terminate)", 1131 SUPPRESS_MUXCLIENT}, 1132 {"?", "this message", SUPPRESS_NEVER}, 1133 }; 1134 1135 static void 1136 print_escape_help(struct sshbuf *b, int escape_char, int mux_client, 1137 int using_stderr) 1138 { 1139 unsigned int i, suppress_flags; 1140 int r; 1141 1142 if ((r = sshbuf_putf(b, 1143 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0) 1144 fatal_fr(r, "sshbuf_putf"); 1145 1146 suppress_flags = 1147 (mux_client ? SUPPRESS_MUXCLIENT : 0) | 1148 (mux_client ? 0 : SUPPRESS_MUXMASTER) | 1149 (using_stderr ? 0 : SUPPRESS_SYSLOG) | 1150 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0); 1151 1152 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { 1153 if (esc_txt[i].flags & suppress_flags) 1154 continue; 1155 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n", 1156 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0) 1157 fatal_fr(r, "sshbuf_putf"); 1158 } 1159 1160 if ((r = sshbuf_putf(b, 1161 " %c%c - send the escape character by typing it twice\r\n" 1162 "(Note that escapes are only recognized immediately after " 1163 "newline.)\r\n", escape_char, escape_char)) != 0) 1164 fatal_fr(r, "sshbuf_putf"); 1165 } 1166 1167 /* 1168 * Process the characters one by one. 1169 */ 1170 static int 1171 process_escapes(struct ssh *ssh, Channel *c, 1172 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr, 1173 char *buf, int len) 1174 { 1175 pid_t pid; 1176 int r, bytes = 0; 1177 u_int i; 1178 u_char ch; 1179 char *s; 1180 struct escape_filter_ctx *efc; 1181 1182 if (c == NULL || c->filter_ctx == NULL || len <= 0) 1183 return 0; 1184 1185 efc = (struct escape_filter_ctx *)c->filter_ctx; 1186 1187 for (i = 0; i < (u_int)len; i++) { 1188 /* Get one character at a time. */ 1189 ch = buf[i]; 1190 1191 if (efc->escape_pending) { 1192 /* We have previously seen an escape character. */ 1193 /* Clear the flag now. */ 1194 efc->escape_pending = 0; 1195 1196 /* Process the escaped character. */ 1197 switch (ch) { 1198 case '.': 1199 /* Terminate the connection. */ 1200 if ((r = sshbuf_putf(berr, "%c.\r\n", 1201 efc->escape_char)) != 0) 1202 fatal_fr(r, "sshbuf_putf"); 1203 if (c && c->ctl_chan != -1) { 1204 channel_force_close(ssh, c, 1); 1205 return 0; 1206 } else 1207 quit_pending = 1; 1208 return -1; 1209 1210 case 'Z' - 64: 1211 /* XXX support this for mux clients */ 1212 if (c && c->ctl_chan != -1) { 1213 char b[16]; 1214 noescape: 1215 if (ch == 'Z' - 64) 1216 snprintf(b, sizeof b, "^Z"); 1217 else 1218 snprintf(b, sizeof b, "%c", ch); 1219 if ((r = sshbuf_putf(berr, 1220 "%c%s escape not available to " 1221 "multiplexed sessions\r\n", 1222 efc->escape_char, b)) != 0) 1223 fatal_fr(r, "sshbuf_putf"); 1224 continue; 1225 } 1226 /* Suspend the program. Inform the user */ 1227 if ((r = sshbuf_putf(berr, 1228 "%c^Z [suspend ssh]\r\n", 1229 efc->escape_char)) != 0) 1230 fatal_fr(r, "sshbuf_putf"); 1231 1232 /* Restore terminal modes and suspend. */ 1233 client_suspend_self(bin, bout, berr); 1234 1235 /* We have been continued. */ 1236 continue; 1237 1238 case 'B': 1239 if ((r = sshbuf_putf(berr, 1240 "%cB\r\n", efc->escape_char)) != 0) 1241 fatal_fr(r, "sshbuf_putf"); 1242 channel_request_start(ssh, c->self, "break", 0); 1243 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 || 1244 (r = sshpkt_send(ssh)) != 0) 1245 fatal_fr(r, "send packet"); 1246 continue; 1247 1248 case 'R': 1249 if (ssh->compat & SSH_BUG_NOREKEY) 1250 logit("Server does not " 1251 "support re-keying"); 1252 else 1253 need_rekeying = 1; 1254 continue; 1255 1256 case 'V': 1257 /* FALLTHROUGH */ 1258 case 'v': 1259 if (c && c->ctl_chan != -1) 1260 goto noescape; 1261 if (!log_is_on_stderr()) { 1262 if ((r = sshbuf_putf(berr, 1263 "%c%c [Logging to syslog]\r\n", 1264 efc->escape_char, ch)) != 0) 1265 fatal_fr(r, "sshbuf_putf"); 1266 continue; 1267 } 1268 if (ch == 'V' && options.log_level > 1269 SYSLOG_LEVEL_QUIET) 1270 log_change_level(--options.log_level); 1271 if (ch == 'v' && options.log_level < 1272 SYSLOG_LEVEL_DEBUG3) 1273 log_change_level(++options.log_level); 1274 if ((r = sshbuf_putf(berr, 1275 "%c%c [LogLevel %s]\r\n", 1276 efc->escape_char, ch, 1277 log_level_name(options.log_level))) != 0) 1278 fatal_fr(r, "sshbuf_putf"); 1279 continue; 1280 1281 case '&': 1282 if (c->ctl_chan != -1) 1283 goto noescape; 1284 /* 1285 * Detach the program (continue to serve 1286 * connections, but put in background and no 1287 * more new connections). 1288 */ 1289 /* Restore tty modes. */ 1290 leave_raw_mode( 1291 options.request_tty == REQUEST_TTY_FORCE); 1292 1293 /* Stop listening for new connections. */ 1294 channel_stop_listening(ssh); 1295 1296 if ((r = sshbuf_putf(berr, "%c& " 1297 "[backgrounded]\n", efc->escape_char)) != 0) 1298 fatal_fr(r, "sshbuf_putf"); 1299 1300 /* Fork into background. */ 1301 pid = fork(); 1302 if (pid == -1) { 1303 error("fork: %.100s", strerror(errno)); 1304 continue; 1305 } 1306 if (pid != 0) { /* This is the parent. */ 1307 /* The parent just exits. */ 1308 exit(0); 1309 } 1310 /* The child continues serving connections. */ 1311 /* fake EOF on stdin */ 1312 if ((r = sshbuf_put_u8(bin, 4)) != 0) 1313 fatal_fr(r, "sshbuf_put_u8"); 1314 return -1; 1315 case '?': 1316 print_escape_help(berr, efc->escape_char, 1317 (c && c->ctl_chan != -1), 1318 log_is_on_stderr()); 1319 continue; 1320 1321 case '#': 1322 if ((r = sshbuf_putf(berr, "%c#\r\n", 1323 efc->escape_char)) != 0) 1324 fatal_fr(r, "sshbuf_putf"); 1325 s = channel_open_message(ssh); 1326 if ((r = sshbuf_put(berr, s, strlen(s))) != 0) 1327 fatal_fr(r, "sshbuf_put"); 1328 free(s); 1329 continue; 1330 1331 case 'C': 1332 if (c && c->ctl_chan != -1) 1333 goto noescape; 1334 if (options.enable_escape_commandline == 0) { 1335 if ((r = sshbuf_putf(berr, 1336 "commandline disabled\r\n")) != 0) 1337 fatal_fr(r, "sshbuf_putf"); 1338 continue; 1339 } 1340 process_cmdline(ssh); 1341 continue; 1342 1343 default: 1344 if (ch != efc->escape_char) { 1345 if ((r = sshbuf_put_u8(bin, 1346 efc->escape_char)) != 0) 1347 fatal_fr(r, "sshbuf_put_u8"); 1348 bytes++; 1349 } 1350 /* Escaped characters fall through here */ 1351 break; 1352 } 1353 } else { 1354 /* 1355 * The previous character was not an escape char. 1356 * Check if this is an escape. 1357 */ 1358 if (last_was_cr && ch == efc->escape_char) { 1359 /* 1360 * It is. Set the flag and continue to 1361 * next character. 1362 */ 1363 efc->escape_pending = 1; 1364 continue; 1365 } 1366 } 1367 1368 /* 1369 * Normal character. Record whether it was a newline, 1370 * and append it to the buffer. 1371 */ 1372 last_was_cr = (ch == '\r' || ch == '\n'); 1373 if ((r = sshbuf_put_u8(bin, ch)) != 0) 1374 fatal_fr(r, "sshbuf_put_u8"); 1375 bytes++; 1376 } 1377 return bytes; 1378 } 1379 1380 /* 1381 * Get packets from the connection input buffer, and process them as long as 1382 * there are packets available. 1383 * 1384 * Any unknown packets received during the actual 1385 * session cause the session to terminate. This is 1386 * intended to make debugging easier since no 1387 * confirmations are sent. Any compatible protocol 1388 * extensions must be negotiated during the 1389 * preparatory phase. 1390 */ 1391 1392 static void 1393 client_process_buffered_input_packets(struct ssh *ssh) 1394 { 1395 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending); 1396 } 1397 1398 /* scan buf[] for '~' before sending data to the peer */ 1399 1400 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ 1401 void * 1402 client_new_escape_filter_ctx(int escape_char) 1403 { 1404 struct escape_filter_ctx *ret; 1405 1406 ret = xcalloc(1, sizeof(*ret)); 1407 ret->escape_pending = 0; 1408 ret->escape_char = escape_char; 1409 return (void *)ret; 1410 } 1411 1412 /* Free the escape filter context on channel free */ 1413 void 1414 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) 1415 { 1416 free(ctx); 1417 } 1418 1419 int 1420 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len) 1421 { 1422 if (c->extended_usage != CHAN_EXTENDED_WRITE) 1423 return 0; 1424 1425 return process_escapes(ssh, c, c->input, c->output, c->extended, 1426 buf, len); 1427 } 1428 1429 static void 1430 client_channel_closed(struct ssh *ssh, int id, int force, void *arg) 1431 { 1432 channel_cancel_cleanup(ssh, id); 1433 session_closed = 1; 1434 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1435 } 1436 1437 /* 1438 * Implements the interactive session with the server. This is called after 1439 * the user has been authenticated, and a command has been started on the 1440 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character 1441 * used as an escape character for terminating or suspending the session. 1442 */ 1443 int 1444 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, 1445 int ssh2_chan_id) 1446 { 1447 struct pollfd *pfd = NULL; 1448 u_int npfd_alloc = 0, npfd_active = 0; 1449 double start_time, total_time; 1450 int channel_did_enqueue = 0, r, len; 1451 u_int64_t ibytes, obytes; 1452 int conn_in_ready, conn_out_ready; 1453 sigset_t bsigset, osigset; 1454 1455 debug("Entering interactive session."); 1456 session_ident = ssh2_chan_id; 1457 1458 if (options.control_master && 1459 !option_clear_or_none(options.control_path)) { 1460 debug("pledge: id"); 1461 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty", 1462 NULL) == -1) 1463 fatal_f("pledge(): %s", strerror(errno)); 1464 1465 } else if (options.forward_x11 || options.permit_local_command) { 1466 debug("pledge: exec"); 1467 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty", 1468 NULL) == -1) 1469 fatal_f("pledge(): %s", strerror(errno)); 1470 1471 } else if (options.update_hostkeys) { 1472 debug("pledge: filesystem"); 1473 if (pledge("stdio rpath wpath cpath unix inet dns proc tty", 1474 NULL) == -1) 1475 fatal_f("pledge(): %s", strerror(errno)); 1476 1477 } else if (!option_clear_or_none(options.proxy_command) || 1478 options.fork_after_authentication) { 1479 debug("pledge: proc"); 1480 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1) 1481 fatal_f("pledge(): %s", strerror(errno)); 1482 1483 } else { 1484 debug("pledge: network"); 1485 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 1486 fatal_f("pledge(): %s", strerror(errno)); 1487 } 1488 1489 /* might be able to tighten now */ 1490 client_repledge(); 1491 1492 start_time = monotime_double(); 1493 1494 /* Initialize variables. */ 1495 last_was_cr = 1; 1496 exit_status = -1; 1497 connection_in = ssh_packet_get_connection_in(ssh); 1498 connection_out = ssh_packet_get_connection_out(ssh); 1499 1500 quit_pending = 0; 1501 1502 /* Initialize buffer. */ 1503 if ((stderr_buffer = sshbuf_new()) == NULL) 1504 fatal_f("sshbuf_new failed"); 1505 1506 client_init_dispatch(ssh); 1507 1508 /* 1509 * Set signal handlers, (e.g. to restore non-blocking mode) 1510 * but don't overwrite SIG_IGN, matches behaviour from rsh(1) 1511 */ 1512 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN) 1513 ssh_signal(SIGHUP, signal_handler); 1514 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN) 1515 ssh_signal(SIGINT, signal_handler); 1516 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN) 1517 ssh_signal(SIGQUIT, signal_handler); 1518 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN) 1519 ssh_signal(SIGTERM, signal_handler); 1520 ssh_signal(SIGWINCH, window_change_handler); 1521 1522 if (have_pty) 1523 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1524 1525 if (session_ident != -1) { 1526 if (escape_char_arg != SSH_ESCAPECHAR_NONE) { 1527 channel_register_filter(ssh, session_ident, 1528 client_simple_escape_filter, NULL, 1529 client_filter_cleanup, 1530 client_new_escape_filter_ctx( 1531 escape_char_arg)); 1532 } 1533 channel_register_cleanup(ssh, session_ident, 1534 client_channel_closed, 0); 1535 } 1536 1537 schedule_server_alive_check(); 1538 1539 if (sigemptyset(&bsigset) == -1 || 1540 sigaddset(&bsigset, SIGHUP) == -1 || 1541 sigaddset(&bsigset, SIGINT) == -1 || 1542 sigaddset(&bsigset, SIGQUIT) == -1 || 1543 sigaddset(&bsigset, SIGTERM) == -1) 1544 error_f("bsigset setup: %s", strerror(errno)); 1545 1546 /* Main loop of the client for the interactive session mode. */ 1547 while (!quit_pending) { 1548 channel_did_enqueue = 0; 1549 1550 /* Process buffered packets sent by the server. */ 1551 client_process_buffered_input_packets(ssh); 1552 1553 if (session_closed && !channel_still_open(ssh)) 1554 break; 1555 1556 if (ssh_packet_is_rekeying(ssh)) { 1557 debug("rekeying in progress"); 1558 } else if (need_rekeying) { 1559 /* manual rekey request */ 1560 debug("need rekeying"); 1561 if ((r = kex_start_rekex(ssh)) != 0) 1562 fatal_fr(r, "kex_start_rekex"); 1563 need_rekeying = 0; 1564 } else { 1565 /* 1566 * Make packets from buffered channel data, and 1567 * enqueue them for sending to the server. 1568 */ 1569 if (ssh_packet_not_very_much_data_to_write(ssh)) 1570 channel_did_enqueue = channel_output_poll(ssh); 1571 1572 /* 1573 * Check if the window size has changed, and buffer a 1574 * message about it to the server if so. 1575 */ 1576 client_check_window_change(ssh); 1577 } 1578 /* 1579 * Wait until we have something to do (something becomes 1580 * available on one of the descriptors). 1581 */ 1582 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1) 1583 error_f("bsigset sigprocmask: %s", strerror(errno)); 1584 if (quit_pending) 1585 break; 1586 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc, 1587 &npfd_active, channel_did_enqueue, &osigset, 1588 &conn_in_ready, &conn_out_ready); 1589 if (sigprocmask(SIG_UNBLOCK, &bsigset, &osigset) == -1) 1590 error_f("osigset sigprocmask: %s", strerror(errno)); 1591 1592 if (quit_pending) 1593 break; 1594 1595 /* Do channel operations. */ 1596 channel_after_poll(ssh, pfd, npfd_active); 1597 1598 /* Buffer input from the connection. */ 1599 if (conn_in_ready) 1600 client_process_net_input(ssh); 1601 1602 if (quit_pending) 1603 break; 1604 1605 /* A timeout may have triggered rekeying */ 1606 if ((r = ssh_packet_check_rekey(ssh)) != 0) 1607 fatal_fr(r, "cannot start rekeying"); 1608 1609 /* 1610 * Send as much buffered packet data as possible to the 1611 * sender. 1612 */ 1613 if (conn_out_ready) { 1614 if ((r = ssh_packet_write_poll(ssh)) != 0) { 1615 sshpkt_fatal(ssh, r, 1616 "%s: ssh_packet_write_poll", __func__); 1617 } 1618 } 1619 1620 /* 1621 * If we are a backgrounded control master, and the 1622 * timeout has expired without any active client 1623 * connections, then quit. 1624 */ 1625 if (control_persist_exit_time > 0) { 1626 if (monotime() >= control_persist_exit_time) { 1627 debug("ControlPersist timeout expired"); 1628 break; 1629 } 1630 } 1631 } 1632 free(pfd); 1633 1634 /* Terminate the session. */ 1635 1636 /* Stop watching for window change. */ 1637 ssh_signal(SIGWINCH, SIG_DFL); 1638 1639 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || 1640 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 || 1641 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 || 1642 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */ 1643 (r = sshpkt_send(ssh)) != 0 || 1644 (r = ssh_packet_write_wait(ssh)) != 0) 1645 fatal_fr(r, "send disconnect"); 1646 1647 channel_free_all(ssh); 1648 1649 if (have_pty) 1650 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1651 1652 /* 1653 * If there was no shell or command requested, there will be no remote 1654 * exit status to be returned. In that case, clear error code if the 1655 * connection was deliberately terminated at this end. 1656 */ 1657 if (options.session_type == SESSION_TYPE_NONE && 1658 received_signal == SIGTERM) { 1659 received_signal = 0; 1660 exit_status = 0; 1661 } 1662 1663 if (received_signal) { 1664 verbose("Killed by signal %d.", (int) received_signal); 1665 cleanup_exit(255); 1666 } 1667 1668 /* 1669 * In interactive mode (with pseudo tty) display a message indicating 1670 * that the connection has been closed. 1671 */ 1672 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO) 1673 quit_message("Connection to %s closed.", host); 1674 1675 /* Output any buffered data for stderr. */ 1676 if (sshbuf_len(stderr_buffer) > 0) { 1677 len = atomicio(vwrite, fileno(stderr), 1678 (u_char *)sshbuf_ptr(stderr_buffer), 1679 sshbuf_len(stderr_buffer)); 1680 if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer)) 1681 error("Write failed flushing stderr buffer."); 1682 else if ((r = sshbuf_consume(stderr_buffer, len)) != 0) 1683 fatal_fr(r, "sshbuf_consume"); 1684 } 1685 1686 /* Clear and free any buffers. */ 1687 sshbuf_free(stderr_buffer); 1688 1689 /* Report bytes transferred, and transfer rates. */ 1690 total_time = monotime_double() - start_time; 1691 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1692 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", 1693 (unsigned long long)obytes, (unsigned long long)ibytes, total_time); 1694 if (total_time > 0) 1695 verbose("Bytes per second: sent %.1f, received %.1f", 1696 obytes / total_time, ibytes / total_time); 1697 /* Return the exit status of the program. */ 1698 debug("Exit status %d", exit_status); 1699 return exit_status; 1700 } 1701 1702 /*********/ 1703 1704 static Channel * 1705 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, 1706 int rchan, u_int rwindow, u_int rmaxpack) 1707 { 1708 Channel *c = NULL; 1709 struct sshbuf *b = NULL; 1710 char *listen_address, *originator_address; 1711 u_int listen_port, originator_port; 1712 int r; 1713 1714 /* Get rest of the packet */ 1715 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 || 1716 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 || 1717 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 || 1718 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1719 (r = sshpkt_get_end(ssh)) != 0) 1720 fatal_fr(r, "parse packet"); 1721 1722 debug_f("listen %s port %d, originator %s port %d", 1723 listen_address, listen_port, originator_address, originator_port); 1724 1725 if (listen_port > 0xffff) 1726 error_f("invalid listen port"); 1727 else if (originator_port > 0xffff) 1728 error_f("invalid originator port"); 1729 else { 1730 c = channel_connect_by_listen_address(ssh, 1731 listen_address, listen_port, "forwarded-tcpip", 1732 originator_address); 1733 } 1734 1735 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1736 if ((b = sshbuf_new()) == NULL) { 1737 error_f("alloc reply"); 1738 goto out; 1739 } 1740 /* reconstruct and send to muxclient */ 1741 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ 1742 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1743 (r = sshbuf_put_cstring(b, request_type)) != 0 || 1744 (r = sshbuf_put_u32(b, rchan)) != 0 || 1745 (r = sshbuf_put_u32(b, rwindow)) != 0 || 1746 (r = sshbuf_put_u32(b, rmaxpack)) != 0 || 1747 (r = sshbuf_put_cstring(b, listen_address)) != 0 || 1748 (r = sshbuf_put_u32(b, listen_port)) != 0 || 1749 (r = sshbuf_put_cstring(b, originator_address)) != 0 || 1750 (r = sshbuf_put_u32(b, originator_port)) != 0 || 1751 (r = sshbuf_put_stringb(c->output, b)) != 0) { 1752 error_fr(r, "compose for muxclient"); 1753 goto out; 1754 } 1755 } 1756 1757 out: 1758 sshbuf_free(b); 1759 free(originator_address); 1760 free(listen_address); 1761 return c; 1762 } 1763 1764 static Channel * 1765 client_request_forwarded_streamlocal(struct ssh *ssh, 1766 const char *request_type, int rchan) 1767 { 1768 Channel *c = NULL; 1769 char *listen_path; 1770 int r; 1771 1772 /* Get the remote path. */ 1773 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 || 1774 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */ 1775 (r = sshpkt_get_end(ssh)) != 0) 1776 fatal_fr(r, "parse packet"); 1777 1778 debug_f("request: %s", listen_path); 1779 1780 c = channel_connect_by_listen_path(ssh, listen_path, 1781 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); 1782 free(listen_path); 1783 return c; 1784 } 1785 1786 static Channel * 1787 client_request_x11(struct ssh *ssh, const char *request_type, int rchan) 1788 { 1789 Channel *c = NULL; 1790 char *originator; 1791 u_int originator_port; 1792 int r, sock; 1793 1794 if (!options.forward_x11) { 1795 error("Warning: ssh server tried X11 forwarding."); 1796 error("Warning: this is probably a break-in attempt by a " 1797 "malicious server."); 1798 return NULL; 1799 } 1800 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) { 1801 verbose("Rejected X11 connection after ForwardX11Timeout " 1802 "expired"); 1803 return NULL; 1804 } 1805 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 1806 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1807 (r = sshpkt_get_end(ssh)) != 0) 1808 fatal_fr(r, "parse packet"); 1809 /* XXX check permission */ 1810 /* XXX range check originator port? */ 1811 debug("client_request_x11: request from %s %u", originator, 1812 originator_port); 1813 free(originator); 1814 sock = x11_connect_display(ssh); 1815 if (sock < 0) 1816 return NULL; 1817 c = channel_new(ssh, "x11-connection", 1818 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1819 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1820 c->force_drain = 1; 1821 return c; 1822 } 1823 1824 static Channel * 1825 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1826 { 1827 Channel *c = NULL; 1828 int r, sock; 1829 1830 if (!options.forward_agent) { 1831 error("Warning: ssh server tried agent forwarding."); 1832 error("Warning: this is probably a break-in attempt by a " 1833 "malicious server."); 1834 return NULL; 1835 } 1836 if (forward_agent_sock_path == NULL) { 1837 r = ssh_get_authentication_socket(&sock); 1838 } else { 1839 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1840 } 1841 if (r != 0) { 1842 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1843 debug_fr(r, "ssh_get_authentication_socket"); 1844 return NULL; 1845 } 1846 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1847 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1848 debug_f("bound agent to hostkey"); 1849 else 1850 debug2_fr(r, "ssh_agent_bind_hostkey"); 1851 1852 c = channel_new(ssh, "agent-connection", 1853 SSH_CHANNEL_OPEN, sock, sock, -1, 1854 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1855 "authentication agent connection", 1); 1856 c->force_drain = 1; 1857 return c; 1858 } 1859 1860 char * 1861 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1862 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1863 { 1864 Channel *c; 1865 int r, fd; 1866 char *ifname = NULL; 1867 1868 if (tun_mode == SSH_TUNMODE_NO) 1869 return 0; 1870 1871 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1872 1873 /* Open local tunnel device */ 1874 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1875 error("Tunnel device open failed."); 1876 return NULL; 1877 } 1878 debug("Tunnel forwarding using interface %s", ifname); 1879 1880 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1881 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1882 c->datagram = 1; 1883 1884 #if defined(SSH_TUN_FILTER) 1885 if (options.tun_open == SSH_TUNMODE_POINTOPOINT) 1886 channel_register_filter(ssh, c->self, sys_tun_infilter, 1887 sys_tun_outfilter, NULL, NULL); 1888 #endif 1889 1890 if (cb != NULL) 1891 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1892 1893 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1894 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1895 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1896 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1897 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1898 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1899 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1900 (r = sshpkt_send(ssh)) != 0) 1901 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1902 1903 return ifname; 1904 } 1905 1906 /* XXXX move to generic input handler */ 1907 static int 1908 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1909 { 1910 Channel *c = NULL; 1911 char *ctype = NULL; 1912 int r; 1913 u_int rchan; 1914 size_t len; 1915 u_int rmaxpack, rwindow; 1916 1917 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1918 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1919 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1920 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1921 goto out; 1922 1923 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1924 ctype, rchan, rwindow, rmaxpack); 1925 1926 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1927 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1928 rmaxpack); 1929 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1930 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1931 } else if (strcmp(ctype, "x11") == 0) { 1932 c = client_request_x11(ssh, ctype, rchan); 1933 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1934 c = client_request_agent(ssh, ctype, rchan); 1935 } 1936 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1937 debug3("proxied to downstream: %s", ctype); 1938 } else if (c != NULL) { 1939 debug("confirm %s", ctype); 1940 c->remote_id = rchan; 1941 c->have_remote_id = 1; 1942 c->remote_window = rwindow; 1943 c->remote_maxpacket = rmaxpack; 1944 if (c->type != SSH_CHANNEL_CONNECTING) { 1945 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1946 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1947 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1948 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1949 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1950 (r = sshpkt_send(ssh)) != 0) 1951 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1952 } 1953 } else { 1954 debug("failure %s", ctype); 1955 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1956 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1957 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1958 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1959 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1960 (r = sshpkt_send(ssh)) != 0) 1961 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1962 } 1963 r = 0; 1964 out: 1965 free(ctype); 1966 return r; 1967 } 1968 1969 static int 1970 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1971 { 1972 Channel *c = NULL; 1973 char *rtype = NULL; 1974 u_char reply; 1975 u_int id, exitval; 1976 int r, success = 0; 1977 1978 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1979 return r; 1980 if (id <= INT_MAX) 1981 c = channel_lookup(ssh, id); 1982 if (channel_proxy_upstream(c, type, seq, ssh)) 1983 return 0; 1984 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1985 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1986 goto out; 1987 1988 debug("client_input_channel_req: channel %u rtype %s reply %d", 1989 id, rtype, reply); 1990 1991 if (c == NULL) { 1992 error("client_input_channel_req: channel %d: " 1993 "unknown channel", id); 1994 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 1995 if ((r = sshpkt_get_end(ssh)) != 0) 1996 goto out; 1997 chan_rcvd_eow(ssh, c); 1998 } else if (strcmp(rtype, "exit-status") == 0) { 1999 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 2000 goto out; 2001 if (c->ctl_chan != -1) { 2002 mux_exit_message(ssh, c, exitval); 2003 success = 1; 2004 } else if ((int)id == session_ident) { 2005 /* Record exit value of local session */ 2006 success = 1; 2007 exit_status = exitval; 2008 } else { 2009 /* Probably for a mux channel that has already closed */ 2010 debug_f("no sink for exit-status on channel %d", 2011 id); 2012 } 2013 if ((r = sshpkt_get_end(ssh)) != 0) 2014 goto out; 2015 } 2016 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 2017 if (!c->have_remote_id) 2018 fatal_f("channel %d: no remote_id", c->self); 2019 if ((r = sshpkt_start(ssh, success ? 2020 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2021 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2022 (r = sshpkt_send(ssh)) != 0) 2023 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2024 } 2025 r = 0; 2026 out: 2027 free(rtype); 2028 return r; 2029 } 2030 2031 struct hostkeys_update_ctx { 2032 /* The hostname and (optionally) IP address string for the server */ 2033 char *host_str, *ip_str; 2034 2035 /* 2036 * Keys received from the server and a flag for each indicating 2037 * whether they already exist in known_hosts. 2038 * keys_match is filled in by hostkeys_find() and later (for new 2039 * keys) by client_global_hostkeys_prove_confirm(). 2040 */ 2041 struct sshkey **keys; 2042 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2043 int *keys_verified; /* flag for new keys verified by server */ 2044 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2045 2046 /* 2047 * Keys that are in known_hosts, but were not present in the update 2048 * from the server (i.e. scheduled to be deleted). 2049 * Filled in by hostkeys_find(). 2050 */ 2051 struct sshkey **old_keys; 2052 size_t nold; 2053 2054 /* Various special cases. */ 2055 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2056 int ca_available; /* saw CA key for this host */ 2057 int old_key_seen; /* saw old key with other name/addr */ 2058 int other_name_seen; /* saw key with other name/addr */ 2059 }; 2060 2061 static void 2062 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2063 { 2064 size_t i; 2065 2066 if (ctx == NULL) 2067 return; 2068 for (i = 0; i < ctx->nkeys; i++) 2069 sshkey_free(ctx->keys[i]); 2070 free(ctx->keys); 2071 free(ctx->keys_match); 2072 free(ctx->keys_verified); 2073 for (i = 0; i < ctx->nold; i++) 2074 sshkey_free(ctx->old_keys[i]); 2075 free(ctx->old_keys); 2076 free(ctx->host_str); 2077 free(ctx->ip_str); 2078 free(ctx); 2079 } 2080 2081 /* 2082 * Returns non-zero if a known_hosts hostname list is not of a form that 2083 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2084 * hostnames lists that do not follow the form host[,ip]. 2085 */ 2086 static int 2087 hostspec_is_complex(const char *hosts) 2088 { 2089 char *cp; 2090 2091 /* wildcard */ 2092 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2093 return 1; 2094 /* single host/ip = ok */ 2095 if ((cp = strchr(hosts, ',')) == NULL) 2096 return 0; 2097 /* more than two entries on the line */ 2098 if (strchr(cp + 1, ',') != NULL) 2099 return 1; 2100 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2101 return 0; 2102 } 2103 2104 /* callback to search for ctx->keys in known_hosts */ 2105 static int 2106 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2107 { 2108 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2109 size_t i; 2110 struct sshkey **tmp; 2111 2112 if (l->key == NULL) 2113 return 0; 2114 if (l->status != HKF_STATUS_MATCHED) { 2115 /* Record if one of the keys appears on a non-matching line */ 2116 for (i = 0; i < ctx->nkeys; i++) { 2117 if (sshkey_equal(l->key, ctx->keys[i])) { 2118 ctx->other_name_seen = 1; 2119 debug3_f("found %s key under different " 2120 "name/addr at %s:%ld", 2121 sshkey_ssh_name(ctx->keys[i]), 2122 l->path, l->linenum); 2123 return 0; 2124 } 2125 } 2126 return 0; 2127 } 2128 /* Don't proceed if revocation or CA markers are present */ 2129 /* XXX relax this */ 2130 if (l->marker != MRK_NONE) { 2131 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2132 l->path, l->linenum); 2133 ctx->complex_hostspec = 1; 2134 return 0; 2135 } 2136 2137 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2138 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2139 if ((l->match & HKF_MATCH_HOST) == 0) { 2140 /* Record if address matched a different hostname. */ 2141 ctx->other_name_seen = 1; 2142 debug3_f("found address %s against different hostname " 2143 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2144 return 0; 2145 } else if ((l->match & HKF_MATCH_IP) == 0) { 2146 /* Record if hostname matched a different address. */ 2147 ctx->other_name_seen = 1; 2148 debug3_f("found hostname %s against different address " 2149 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2150 } 2151 } 2152 2153 /* 2154 * UpdateHostkeys is skipped for wildcard host names and hostnames 2155 * that contain more than two entries (ssh never writes these). 2156 */ 2157 if (hostspec_is_complex(l->hosts)) { 2158 debug3_f("hostkeys file %s:%ld complex host specification", 2159 l->path, l->linenum); 2160 ctx->complex_hostspec = 1; 2161 return 0; 2162 } 2163 2164 /* Mark off keys we've already seen for this host */ 2165 for (i = 0; i < ctx->nkeys; i++) { 2166 if (!sshkey_equal(l->key, ctx->keys[i])) 2167 continue; 2168 debug3_f("found %s key at %s:%ld", 2169 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2170 ctx->keys_match[i] |= l->match; 2171 return 0; 2172 } 2173 /* This line contained a key that not offered by the server */ 2174 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2175 l->path, l->linenum); 2176 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2177 sizeof(*ctx->old_keys))) == NULL) 2178 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2179 ctx->old_keys = tmp; 2180 ctx->old_keys[ctx->nold++] = l->key; 2181 l->key = NULL; 2182 2183 return 0; 2184 } 2185 2186 /* callback to search for ctx->old_keys in known_hosts under other names */ 2187 static int 2188 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2189 { 2190 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2191 size_t i; 2192 int hashed; 2193 2194 /* only care about lines that *don't* match the active host spec */ 2195 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2196 return 0; 2197 2198 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2199 for (i = 0; i < ctx->nold; i++) { 2200 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2201 continue; 2202 debug3_f("found deprecated %s key at %s:%ld as %s", 2203 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2204 hashed ? "[HASHED]" : l->hosts); 2205 ctx->old_key_seen = 1; 2206 break; 2207 } 2208 return 0; 2209 } 2210 2211 /* 2212 * Check known_hosts files for deprecated keys under other names. Returns 0 2213 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2214 * exist under names other than the active hostname/IP. 2215 */ 2216 static int 2217 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2218 { 2219 size_t i; 2220 int r; 2221 2222 debug2_f("checking for %zu deprecated keys", ctx->nold); 2223 for (i = 0; i < options.num_user_hostfiles; i++) { 2224 debug3_f("searching %s for %s / %s", 2225 options.user_hostfiles[i], ctx->host_str, 2226 ctx->ip_str ? ctx->ip_str : "(none)"); 2227 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2228 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2229 HKF_WANT_PARSE_KEY, 0)) != 0) { 2230 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2231 debug_f("hostkeys file %s does not exist", 2232 options.user_hostfiles[i]); 2233 continue; 2234 } 2235 error_fr(r, "hostkeys_foreach failed for %s", 2236 options.user_hostfiles[i]); 2237 return -1; 2238 } 2239 } 2240 return 0; 2241 } 2242 2243 static void 2244 hostkey_change_preamble(LogLevel loglevel) 2245 { 2246 do_log2(loglevel, "The server has updated its host keys."); 2247 do_log2(loglevel, "These changes were verified by the server's " 2248 "existing trusted key."); 2249 } 2250 2251 static void 2252 update_known_hosts(struct hostkeys_update_ctx *ctx) 2253 { 2254 int r, was_raw = 0, first = 1; 2255 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2256 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2257 char *fp, *response; 2258 size_t i; 2259 struct stat sb; 2260 2261 for (i = 0; i < ctx->nkeys; i++) { 2262 if (!ctx->keys_verified[i]) 2263 continue; 2264 if ((fp = sshkey_fingerprint(ctx->keys[i], 2265 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2266 fatal_f("sshkey_fingerprint failed"); 2267 if (first && asking) 2268 hostkey_change_preamble(loglevel); 2269 do_log2(loglevel, "Learned new hostkey: %s %s", 2270 sshkey_type(ctx->keys[i]), fp); 2271 first = 0; 2272 free(fp); 2273 } 2274 for (i = 0; i < ctx->nold; i++) { 2275 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2276 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2277 fatal_f("sshkey_fingerprint failed"); 2278 if (first && asking) 2279 hostkey_change_preamble(loglevel); 2280 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2281 sshkey_type(ctx->old_keys[i]), fp); 2282 first = 0; 2283 free(fp); 2284 } 2285 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2286 if (get_saved_tio() != NULL) { 2287 leave_raw_mode(1); 2288 was_raw = 1; 2289 } 2290 response = NULL; 2291 for (i = 0; !quit_pending && i < 3; i++) { 2292 free(response); 2293 response = read_passphrase("Accept updated hostkeys? " 2294 "(yes/no): ", RP_ECHO); 2295 if (response != NULL && strcasecmp(response, "yes") == 0) 2296 break; 2297 else if (quit_pending || response == NULL || 2298 strcasecmp(response, "no") == 0) { 2299 options.update_hostkeys = 0; 2300 break; 2301 } else { 2302 do_log2(loglevel, "Please enter " 2303 "\"yes\" or \"no\""); 2304 } 2305 } 2306 if (quit_pending || i >= 3 || response == NULL) 2307 options.update_hostkeys = 0; 2308 free(response); 2309 if (was_raw) 2310 enter_raw_mode(1); 2311 } 2312 if (options.update_hostkeys == 0) 2313 return; 2314 /* 2315 * Now that all the keys are verified, we can go ahead and replace 2316 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2317 * cancel the operation). 2318 */ 2319 for (i = 0; i < options.num_user_hostfiles; i++) { 2320 /* 2321 * NB. keys are only added to hostfiles[0], for the rest we 2322 * just delete the hostname entries. 2323 */ 2324 if (stat(options.user_hostfiles[i], &sb) != 0) { 2325 if (errno == ENOENT) { 2326 debug_f("known hosts file %s does not " 2327 "exist", options.user_hostfiles[i]); 2328 } else { 2329 error_f("known hosts file %s " 2330 "inaccessible: %s", 2331 options.user_hostfiles[i], strerror(errno)); 2332 } 2333 continue; 2334 } 2335 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2336 ctx->host_str, ctx->ip_str, 2337 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2338 options.hash_known_hosts, 0, 2339 options.fingerprint_hash)) != 0) { 2340 error_fr(r, "hostfile_replace_entries failed for %s", 2341 options.user_hostfiles[i]); 2342 } 2343 } 2344 } 2345 2346 static void 2347 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2348 u_int32_t seq, void *_ctx) 2349 { 2350 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2351 size_t i, ndone; 2352 struct sshbuf *signdata; 2353 int r, plaintype; 2354 const u_char *sig; 2355 const char *rsa_kexalg = NULL; 2356 char *alg = NULL; 2357 size_t siglen; 2358 2359 if (ctx->nnew == 0) 2360 fatal_f("ctx->nnew == 0"); /* sanity */ 2361 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2362 error("Server failed to confirm ownership of " 2363 "private host keys"); 2364 hostkeys_update_ctx_free(ctx); 2365 return; 2366 } 2367 if (sshkey_type_plain(sshkey_type_from_name( 2368 ssh->kex->hostkey_alg)) == KEY_RSA) 2369 rsa_kexalg = ssh->kex->hostkey_alg; 2370 if ((signdata = sshbuf_new()) == NULL) 2371 fatal_f("sshbuf_new failed"); 2372 /* 2373 * Expect a signature for each of the ctx->nnew private keys we 2374 * haven't seen before. They will be in the same order as the 2375 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2376 */ 2377 for (ndone = i = 0; i < ctx->nkeys; i++) { 2378 if (ctx->keys_match[i]) 2379 continue; 2380 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2381 /* Prepare data to be signed: session ID, unique string, key */ 2382 sshbuf_reset(signdata); 2383 if ( (r = sshbuf_put_cstring(signdata, 2384 "hostkeys-prove-00@openssh.com")) != 0 || 2385 (r = sshbuf_put_stringb(signdata, 2386 ssh->kex->session_id)) != 0 || 2387 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2388 fatal_fr(r, "compose signdata"); 2389 /* Extract and verify signature */ 2390 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2391 error_fr(r, "parse sig"); 2392 goto out; 2393 } 2394 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2395 error_fr(r, "server gave unintelligible signature " 2396 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2397 goto out; 2398 } 2399 /* 2400 * Special case for RSA keys: if a RSA hostkey was negotiated, 2401 * then use its signature type for verification of RSA hostkey 2402 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2403 */ 2404 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2405 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2406 debug_f("server used untrusted RSA signature algorithm " 2407 "%s for key %zu, disregarding", alg, i); 2408 free(alg); 2409 /* zap the key from the list */ 2410 sshkey_free(ctx->keys[i]); 2411 ctx->keys[i] = NULL; 2412 ndone++; 2413 continue; 2414 } 2415 debug3_f("verify %s key %zu using sigalg %s", 2416 sshkey_type(ctx->keys[i]), i, alg); 2417 free(alg); 2418 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2419 sshbuf_ptr(signdata), sshbuf_len(signdata), 2420 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2421 error_fr(r, "server gave bad signature for %s key %zu", 2422 sshkey_type(ctx->keys[i]), i); 2423 goto out; 2424 } 2425 /* Key is good. Mark it as 'seen' */ 2426 ctx->keys_verified[i] = 1; 2427 ndone++; 2428 } 2429 /* Shouldn't happen */ 2430 if (ndone != ctx->nnew) 2431 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2432 if ((r = sshpkt_get_end(ssh)) != 0) { 2433 error_f("protocol error"); 2434 goto out; 2435 } 2436 2437 /* Make the edits to known_hosts */ 2438 update_known_hosts(ctx); 2439 out: 2440 hostkeys_update_ctx_free(ctx); 2441 hostkeys_update_complete = 1; 2442 client_repledge(); 2443 } 2444 2445 /* 2446 * Returns non-zero if the key is accepted by HostkeyAlgorithms. 2447 * Made slightly less trivial by the multiple RSA signature algorithm names. 2448 */ 2449 static int 2450 key_accepted_by_hostkeyalgs(const struct sshkey *key) 2451 { 2452 const char *ktype = sshkey_ssh_name(key); 2453 const char *hostkeyalgs = options.hostkeyalgorithms; 2454 2455 if (key->type == KEY_UNSPEC) 2456 return 0; 2457 if (key->type == KEY_RSA && 2458 (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 || 2459 match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1)) 2460 return 1; 2461 return match_pattern_list(ktype, hostkeyalgs, 0) == 1; 2462 } 2463 2464 /* 2465 * Handle hostkeys-00@openssh.com global request to inform the client of all 2466 * the server's hostkeys. The keys are checked against the user's 2467 * HostkeyAlgorithms preference before they are accepted. 2468 */ 2469 static int 2470 client_input_hostkeys(struct ssh *ssh) 2471 { 2472 const u_char *blob = NULL; 2473 size_t i, len = 0; 2474 struct sshbuf *buf = NULL; 2475 struct sshkey *key = NULL, **tmp; 2476 int r, prove_sent = 0; 2477 char *fp; 2478 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2479 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2480 struct hostkeys_update_ctx *ctx = NULL; 2481 u_int want; 2482 2483 if (hostkeys_seen) 2484 fatal_f("server already sent hostkeys"); 2485 if (!can_update_hostkeys()) 2486 return 1; 2487 hostkeys_seen = 1; 2488 2489 ctx = xcalloc(1, sizeof(*ctx)); 2490 while (ssh_packet_remaining(ssh) > 0) { 2491 sshkey_free(key); 2492 key = NULL; 2493 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2494 error_fr(r, "parse key"); 2495 goto out; 2496 } 2497 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2498 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2499 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2500 "convert key"); 2501 continue; 2502 } 2503 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2504 SSH_FP_DEFAULT); 2505 debug3_f("received %s key %s", sshkey_type(key), fp); 2506 free(fp); 2507 2508 if (!key_accepted_by_hostkeyalgs(key)) { 2509 debug3_f("%s key not permitted by " 2510 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2511 continue; 2512 } 2513 /* Skip certs */ 2514 if (sshkey_is_cert(key)) { 2515 debug3_f("%s key is a certificate; skipping", 2516 sshkey_ssh_name(key)); 2517 continue; 2518 } 2519 /* Ensure keys are unique */ 2520 for (i = 0; i < ctx->nkeys; i++) { 2521 if (sshkey_equal(key, ctx->keys[i])) { 2522 error_f("received duplicated %s host key", 2523 sshkey_ssh_name(key)); 2524 goto out; 2525 } 2526 } 2527 /* Key is good, record it */ 2528 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2529 sizeof(*ctx->keys))) == NULL) 2530 fatal_f("recallocarray failed nkeys = %zu", 2531 ctx->nkeys); 2532 ctx->keys = tmp; 2533 ctx->keys[ctx->nkeys++] = key; 2534 key = NULL; 2535 } 2536 2537 if (ctx->nkeys == 0) { 2538 debug_f("server sent no hostkeys"); 2539 goto out; 2540 } 2541 2542 if ((ctx->keys_match = calloc(ctx->nkeys, 2543 sizeof(*ctx->keys_match))) == NULL || 2544 (ctx->keys_verified = calloc(ctx->nkeys, 2545 sizeof(*ctx->keys_verified))) == NULL) 2546 fatal_f("calloc failed"); 2547 2548 get_hostfile_hostname_ipaddr(host, 2549 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2550 options.port, &ctx->host_str, 2551 options.check_host_ip ? &ctx->ip_str : NULL); 2552 2553 /* Find which keys we already know about. */ 2554 for (i = 0; i < options.num_user_hostfiles; i++) { 2555 debug_f("searching %s for %s / %s", 2556 options.user_hostfiles[i], ctx->host_str, 2557 ctx->ip_str ? ctx->ip_str : "(none)"); 2558 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2559 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2560 HKF_WANT_PARSE_KEY, 0)) != 0) { 2561 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2562 debug_f("hostkeys file %s does not exist", 2563 options.user_hostfiles[i]); 2564 continue; 2565 } 2566 error_fr(r, "hostkeys_foreach failed for %s", 2567 options.user_hostfiles[i]); 2568 goto out; 2569 } 2570 } 2571 2572 /* Figure out if we have any new keys to add */ 2573 ctx->nnew = ctx->nincomplete = 0; 2574 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2575 for (i = 0; i < ctx->nkeys; i++) { 2576 if (ctx->keys_match[i] == 0) 2577 ctx->nnew++; 2578 if ((ctx->keys_match[i] & want) != want) 2579 ctx->nincomplete++; 2580 } 2581 2582 debug3_f("%zu server keys: %zu new, %zu retained, " 2583 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2584 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2585 ctx->nincomplete, ctx->nold); 2586 2587 if (ctx->nnew == 0 && ctx->nold == 0) { 2588 debug_f("no new or deprecated keys from server"); 2589 goto out; 2590 } 2591 2592 /* Various reasons why we cannot proceed with the update */ 2593 if (ctx->complex_hostspec) { 2594 debug_f("CA/revocation marker, manual host list or wildcard " 2595 "host pattern found, skipping UserKnownHostsFile update"); 2596 goto out; 2597 } 2598 if (ctx->other_name_seen) { 2599 debug_f("host key found matching a different name/address, " 2600 "skipping UserKnownHostsFile update"); 2601 goto out; 2602 } 2603 /* 2604 * If removing keys, check whether they appear under different 2605 * names/addresses and refuse to proceed if they do. This avoids 2606 * cases such as hosts with multiple names becoming inconsistent 2607 * with regards to CheckHostIP entries. 2608 * XXX UpdateHostkeys=force to override this (and other) checks? 2609 */ 2610 if (ctx->nold != 0) { 2611 if (check_old_keys_othernames(ctx) != 0) 2612 goto out; /* error already logged */ 2613 if (ctx->old_key_seen) { 2614 debug_f("key(s) for %s%s%s exist under other names; " 2615 "skipping UserKnownHostsFile update", 2616 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2617 ctx->ip_str == NULL ? "" : ctx->ip_str); 2618 goto out; 2619 } 2620 } 2621 2622 if (ctx->nnew == 0) { 2623 /* 2624 * We have some keys to remove or fix matching for. 2625 * We can proceed to do this without requiring a fresh proof 2626 * from the server. 2627 */ 2628 update_known_hosts(ctx); 2629 goto out; 2630 } 2631 /* 2632 * We have received previously-unseen keys from the server. 2633 * Ask the server to confirm ownership of the private halves. 2634 */ 2635 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2636 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2637 (r = sshpkt_put_cstring(ssh, 2638 "hostkeys-prove-00@openssh.com")) != 0 || 2639 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2640 fatal_fr(r, "prepare hostkeys-prove"); 2641 if ((buf = sshbuf_new()) == NULL) 2642 fatal_f("sshbuf_new"); 2643 for (i = 0; i < ctx->nkeys; i++) { 2644 if (ctx->keys_match[i]) 2645 continue; 2646 sshbuf_reset(buf); 2647 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2648 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2649 fatal_fr(r, "assemble hostkeys-prove"); 2650 } 2651 if ((r = sshpkt_send(ssh)) != 0) 2652 fatal_fr(r, "send hostkeys-prove"); 2653 client_register_global_confirm( 2654 client_global_hostkeys_prove_confirm, ctx); 2655 ctx = NULL; /* will be freed in callback */ 2656 prove_sent = 1; 2657 2658 /* Success */ 2659 out: 2660 hostkeys_update_ctx_free(ctx); 2661 sshkey_free(key); 2662 sshbuf_free(buf); 2663 if (!prove_sent) { 2664 /* UpdateHostkeys handling completed */ 2665 hostkeys_update_complete = 1; 2666 client_repledge(); 2667 } 2668 /* 2669 * NB. Return success for all cases. The server doesn't need to know 2670 * what the client does with its hosts file. 2671 */ 2672 return 1; 2673 } 2674 2675 static int 2676 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2677 { 2678 char *rtype; 2679 u_char want_reply; 2680 int r, success = 0; 2681 2682 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2683 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2684 goto out; 2685 debug("client_input_global_request: rtype %s want_reply %d", 2686 rtype, want_reply); 2687 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2688 success = client_input_hostkeys(ssh); 2689 if (want_reply) { 2690 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2691 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2692 (r = sshpkt_send(ssh)) != 0 || 2693 (r = ssh_packet_write_wait(ssh)) != 0) 2694 goto out; 2695 } 2696 r = 0; 2697 out: 2698 free(rtype); 2699 return r; 2700 } 2701 2702 static void 2703 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2704 { 2705 int r; 2706 2707 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2708 channel_request_start(ssh, id, "env", 0); 2709 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2710 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2711 (r = sshpkt_send(ssh)) != 0) 2712 fatal_fr(r, "send setenv"); 2713 } 2714 2715 void 2716 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2717 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2718 char **env) 2719 { 2720 size_t i, j, len; 2721 int matched, r; 2722 char *name, *val; 2723 Channel *c = NULL; 2724 2725 debug2_f("id %d", id); 2726 2727 if ((c = channel_lookup(ssh, id)) == NULL) 2728 fatal_f("channel %d: unknown channel", id); 2729 2730 ssh_packet_set_interactive(ssh, want_tty, 2731 options.ip_qos_interactive, options.ip_qos_bulk); 2732 2733 if (want_tty) { 2734 struct winsize ws; 2735 2736 /* Store window size in the packet. */ 2737 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2738 memset(&ws, 0, sizeof(ws)); 2739 2740 channel_request_start(ssh, id, "pty-req", 1); 2741 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2742 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2743 != 0 || 2744 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2745 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2746 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2747 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2748 fatal_fr(r, "build pty-req"); 2749 if (tiop == NULL) 2750 tiop = get_saved_tio(); 2751 ssh_tty_make_modes(ssh, -1, tiop); 2752 if ((r = sshpkt_send(ssh)) != 0) 2753 fatal_fr(r, "send pty-req"); 2754 /* XXX wait for reply */ 2755 c->client_tty = 1; 2756 } 2757 2758 /* Transfer any environment variables from client to server */ 2759 if (options.num_send_env != 0 && env != NULL) { 2760 debug("Sending environment."); 2761 for (i = 0; env[i] != NULL; i++) { 2762 /* Split */ 2763 name = xstrdup(env[i]); 2764 if ((val = strchr(name, '=')) == NULL) { 2765 free(name); 2766 continue; 2767 } 2768 *val++ = '\0'; 2769 2770 matched = 0; 2771 for (j = 0; j < options.num_send_env; j++) { 2772 if (match_pattern(name, options.send_env[j])) { 2773 matched = 1; 2774 break; 2775 } 2776 } 2777 if (!matched) { 2778 debug3("Ignored env %s", name); 2779 free(name); 2780 continue; 2781 } 2782 client_send_env(ssh, id, name, val); 2783 free(name); 2784 } 2785 } 2786 for (i = 0; i < options.num_setenv; i++) { 2787 /* Split */ 2788 name = xstrdup(options.setenv[i]); 2789 if ((val = strchr(name, '=')) == NULL) { 2790 free(name); 2791 continue; 2792 } 2793 *val++ = '\0'; 2794 client_send_env(ssh, id, name, val); 2795 free(name); 2796 } 2797 2798 len = sshbuf_len(cmd); 2799 if (len > 0) { 2800 if (len > 900) 2801 len = 900; 2802 if (want_subsystem) { 2803 debug("Sending subsystem: %.*s", 2804 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2805 channel_request_start(ssh, id, "subsystem", 1); 2806 client_expect_confirm(ssh, id, "subsystem", 2807 CONFIRM_CLOSE); 2808 } else { 2809 debug("Sending command: %.*s", 2810 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2811 channel_request_start(ssh, id, "exec", 1); 2812 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2813 } 2814 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2815 (r = sshpkt_send(ssh)) != 0) 2816 fatal_fr(r, "send command"); 2817 } else { 2818 channel_request_start(ssh, id, "shell", 1); 2819 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2820 if ((r = sshpkt_send(ssh)) != 0) 2821 fatal_fr(r, "send shell"); 2822 } 2823 2824 session_setup_complete = 1; 2825 client_repledge(); 2826 } 2827 2828 static void 2829 client_init_dispatch(struct ssh *ssh) 2830 { 2831 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2832 2833 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2834 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2835 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2836 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2837 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2838 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2839 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2840 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2841 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2842 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2843 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2844 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2845 2846 /* rekeying */ 2847 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2848 2849 /* global request reply messages */ 2850 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2851 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2852 } 2853 2854 void 2855 client_stop_mux(void) 2856 { 2857 if (options.control_path != NULL && muxserver_sock != -1) 2858 unlink(options.control_path); 2859 /* 2860 * If we are in persist mode, or don't have a shell, signal that we 2861 * should close when all active channels are closed. 2862 */ 2863 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2864 session_closed = 1; 2865 setproctitle("[stopped mux]"); 2866 } 2867 } 2868 2869 /* client specific fatal cleanup */ 2870 void 2871 cleanup_exit(int i) 2872 { 2873 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2874 if (options.control_path != NULL && muxserver_sock != -1) 2875 unlink(options.control_path); 2876 ssh_kill_proxy_command(); 2877 _exit(i); 2878 } 2879