1 /* $OpenBSD: clientloop.c,v 1.402 2023/11/24 00:31:30 dtucker 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->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 /* Otherwise if we were due to send, 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, len; 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 /* Initialize buffer. */ 1502 if ((stderr_buffer = sshbuf_new()) == NULL) 1503 fatal_f("sshbuf_new failed"); 1504 1505 client_init_dispatch(ssh); 1506 1507 /* 1508 * Set signal handlers, (e.g. to restore non-blocking mode) 1509 * but don't overwrite SIG_IGN, matches behaviour from rsh(1) 1510 */ 1511 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN) 1512 ssh_signal(SIGHUP, signal_handler); 1513 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN) 1514 ssh_signal(SIGINT, signal_handler); 1515 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN) 1516 ssh_signal(SIGQUIT, signal_handler); 1517 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN) 1518 ssh_signal(SIGTERM, signal_handler); 1519 ssh_signal(SIGWINCH, window_change_handler); 1520 1521 if (have_pty) 1522 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1523 1524 if (session_ident != -1) { 1525 if (escape_char_arg != SSH_ESCAPECHAR_NONE) { 1526 channel_register_filter(ssh, session_ident, 1527 client_simple_escape_filter, NULL, 1528 client_filter_cleanup, 1529 client_new_escape_filter_ctx( 1530 escape_char_arg)); 1531 } 1532 channel_register_cleanup(ssh, session_ident, 1533 client_channel_closed, 0); 1534 } 1535 1536 schedule_server_alive_check(); 1537 1538 if (sigemptyset(&bsigset) == -1 || 1539 sigaddset(&bsigset, SIGHUP) == -1 || 1540 sigaddset(&bsigset, SIGINT) == -1 || 1541 sigaddset(&bsigset, SIGQUIT) == -1 || 1542 sigaddset(&bsigset, SIGTERM) == -1) 1543 error_f("bsigset setup: %s", strerror(errno)); 1544 1545 /* Main loop of the client for the interactive session mode. */ 1546 while (!quit_pending) { 1547 channel_did_enqueue = 0; 1548 1549 /* Process buffered packets sent by the server. */ 1550 client_process_buffered_input_packets(ssh); 1551 1552 if (session_closed && !channel_still_open(ssh)) 1553 break; 1554 1555 if (ssh_packet_is_rekeying(ssh)) { 1556 debug("rekeying in progress"); 1557 } else if (need_rekeying) { 1558 /* manual rekey request */ 1559 debug("need rekeying"); 1560 if ((r = kex_start_rekex(ssh)) != 0) 1561 fatal_fr(r, "kex_start_rekex"); 1562 need_rekeying = 0; 1563 } else { 1564 /* 1565 * Make packets from buffered channel data, and 1566 * enqueue them for sending to the server. 1567 */ 1568 if (ssh_packet_not_very_much_data_to_write(ssh)) 1569 channel_did_enqueue = channel_output_poll(ssh); 1570 1571 /* 1572 * Check if the window size has changed, and buffer a 1573 * message about it to the server if so. 1574 */ 1575 client_check_window_change(ssh); 1576 } 1577 /* 1578 * Wait until we have something to do (something becomes 1579 * available on one of the descriptors). 1580 */ 1581 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1) 1582 error_f("bsigset sigprocmask: %s", strerror(errno)); 1583 if (quit_pending) 1584 break; 1585 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc, 1586 &npfd_active, channel_did_enqueue, &osigset, 1587 &conn_in_ready, &conn_out_ready); 1588 if (sigprocmask(SIG_UNBLOCK, &bsigset, &osigset) == -1) 1589 error_f("osigset sigprocmask: %s", strerror(errno)); 1590 1591 if (quit_pending) 1592 break; 1593 1594 /* Do channel operations. */ 1595 channel_after_poll(ssh, pfd, npfd_active); 1596 1597 /* Buffer input from the connection. */ 1598 if (conn_in_ready) 1599 client_process_net_input(ssh); 1600 1601 if (quit_pending) 1602 break; 1603 1604 /* A timeout may have triggered rekeying */ 1605 if ((r = ssh_packet_check_rekey(ssh)) != 0) 1606 fatal_fr(r, "cannot start rekeying"); 1607 1608 /* 1609 * Send as much buffered packet data as possible to the 1610 * sender. 1611 */ 1612 if (conn_out_ready) { 1613 if ((r = ssh_packet_write_poll(ssh)) != 0) { 1614 sshpkt_fatal(ssh, r, 1615 "%s: ssh_packet_write_poll", __func__); 1616 } 1617 } 1618 1619 /* 1620 * If we are a backgrounded control master, and the 1621 * timeout has expired without any active client 1622 * connections, then quit. 1623 */ 1624 if (control_persist_exit_time > 0) { 1625 if (monotime() >= control_persist_exit_time) { 1626 debug("ControlPersist timeout expired"); 1627 break; 1628 } 1629 } 1630 } 1631 free(pfd); 1632 1633 /* Terminate the session. */ 1634 1635 /* Stop watching for window change. */ 1636 ssh_signal(SIGWINCH, SIG_DFL); 1637 1638 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || 1639 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 || 1640 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 || 1641 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */ 1642 (r = sshpkt_send(ssh)) != 0 || 1643 (r = ssh_packet_write_wait(ssh)) != 0) 1644 fatal_fr(r, "send disconnect"); 1645 1646 channel_free_all(ssh); 1647 1648 if (have_pty) 1649 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1650 1651 /* 1652 * If there was no shell or command requested, there will be no remote 1653 * exit status to be returned. In that case, clear error code if the 1654 * connection was deliberately terminated at this end. 1655 */ 1656 if (options.session_type == SESSION_TYPE_NONE && 1657 received_signal == SIGTERM) { 1658 received_signal = 0; 1659 exit_status = 0; 1660 } 1661 1662 if (received_signal) { 1663 verbose("Killed by signal %d.", (int) received_signal); 1664 cleanup_exit(255); 1665 } 1666 1667 /* 1668 * In interactive mode (with pseudo tty) display a message indicating 1669 * that the connection has been closed. 1670 */ 1671 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO) 1672 quit_message("Connection to %s closed.", host); 1673 1674 /* Output any buffered data for stderr. */ 1675 if (sshbuf_len(stderr_buffer) > 0) { 1676 len = atomicio(vwrite, fileno(stderr), 1677 (u_char *)sshbuf_ptr(stderr_buffer), 1678 sshbuf_len(stderr_buffer)); 1679 if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer)) 1680 error("Write failed flushing stderr buffer."); 1681 else if ((r = sshbuf_consume(stderr_buffer, len)) != 0) 1682 fatal_fr(r, "sshbuf_consume"); 1683 } 1684 1685 /* Clear and free any buffers. */ 1686 sshbuf_free(stderr_buffer); 1687 1688 /* Report bytes transferred, and transfer rates. */ 1689 total_time = monotime_double() - start_time; 1690 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1691 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", 1692 (unsigned long long)obytes, (unsigned long long)ibytes, total_time); 1693 if (total_time > 0) 1694 verbose("Bytes per second: sent %.1f, received %.1f", 1695 obytes / total_time, ibytes / total_time); 1696 /* Return the exit status of the program. */ 1697 debug("Exit status %d", exit_status); 1698 return exit_status; 1699 } 1700 1701 /*********/ 1702 1703 static Channel * 1704 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, 1705 int rchan, u_int rwindow, u_int rmaxpack) 1706 { 1707 Channel *c = NULL; 1708 struct sshbuf *b = NULL; 1709 char *listen_address, *originator_address; 1710 u_int listen_port, originator_port; 1711 int r; 1712 1713 /* Get rest of the packet */ 1714 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 || 1715 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 || 1716 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 || 1717 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1718 (r = sshpkt_get_end(ssh)) != 0) 1719 fatal_fr(r, "parse packet"); 1720 1721 debug_f("listen %s port %d, originator %s port %d", 1722 listen_address, listen_port, originator_address, originator_port); 1723 1724 if (listen_port > 0xffff) 1725 error_f("invalid listen port"); 1726 else if (originator_port > 0xffff) 1727 error_f("invalid originator port"); 1728 else { 1729 c = channel_connect_by_listen_address(ssh, 1730 listen_address, listen_port, "forwarded-tcpip", 1731 originator_address); 1732 } 1733 1734 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1735 if ((b = sshbuf_new()) == NULL) { 1736 error_f("alloc reply"); 1737 goto out; 1738 } 1739 /* reconstruct and send to muxclient */ 1740 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ 1741 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1742 (r = sshbuf_put_cstring(b, request_type)) != 0 || 1743 (r = sshbuf_put_u32(b, rchan)) != 0 || 1744 (r = sshbuf_put_u32(b, rwindow)) != 0 || 1745 (r = sshbuf_put_u32(b, rmaxpack)) != 0 || 1746 (r = sshbuf_put_cstring(b, listen_address)) != 0 || 1747 (r = sshbuf_put_u32(b, listen_port)) != 0 || 1748 (r = sshbuf_put_cstring(b, originator_address)) != 0 || 1749 (r = sshbuf_put_u32(b, originator_port)) != 0 || 1750 (r = sshbuf_put_stringb(c->output, b)) != 0) { 1751 error_fr(r, "compose for muxclient"); 1752 goto out; 1753 } 1754 } 1755 1756 out: 1757 sshbuf_free(b); 1758 free(originator_address); 1759 free(listen_address); 1760 return c; 1761 } 1762 1763 static Channel * 1764 client_request_forwarded_streamlocal(struct ssh *ssh, 1765 const char *request_type, int rchan) 1766 { 1767 Channel *c = NULL; 1768 char *listen_path; 1769 int r; 1770 1771 /* Get the remote path. */ 1772 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 || 1773 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */ 1774 (r = sshpkt_get_end(ssh)) != 0) 1775 fatal_fr(r, "parse packet"); 1776 1777 debug_f("request: %s", listen_path); 1778 1779 c = channel_connect_by_listen_path(ssh, listen_path, 1780 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); 1781 free(listen_path); 1782 return c; 1783 } 1784 1785 static Channel * 1786 client_request_x11(struct ssh *ssh, const char *request_type, int rchan) 1787 { 1788 Channel *c = NULL; 1789 char *originator; 1790 u_int originator_port; 1791 int r, sock; 1792 1793 if (!options.forward_x11) { 1794 error("Warning: ssh server tried X11 forwarding."); 1795 error("Warning: this is probably a break-in attempt by a " 1796 "malicious server."); 1797 return NULL; 1798 } 1799 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) { 1800 verbose("Rejected X11 connection after ForwardX11Timeout " 1801 "expired"); 1802 return NULL; 1803 } 1804 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 1805 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1806 (r = sshpkt_get_end(ssh)) != 0) 1807 fatal_fr(r, "parse packet"); 1808 /* XXX check permission */ 1809 /* XXX range check originator port? */ 1810 debug("client_request_x11: request from %s %u", originator, 1811 originator_port); 1812 free(originator); 1813 sock = x11_connect_display(ssh); 1814 if (sock < 0) 1815 return NULL; 1816 c = channel_new(ssh, "x11-connection", 1817 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1818 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1819 c->force_drain = 1; 1820 return c; 1821 } 1822 1823 static Channel * 1824 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1825 { 1826 Channel *c = NULL; 1827 int r, sock; 1828 1829 if (!options.forward_agent) { 1830 error("Warning: ssh server tried agent forwarding."); 1831 error("Warning: this is probably a break-in attempt by a " 1832 "malicious server."); 1833 return NULL; 1834 } 1835 if (forward_agent_sock_path == NULL) { 1836 r = ssh_get_authentication_socket(&sock); 1837 } else { 1838 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1839 } 1840 if (r != 0) { 1841 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1842 debug_fr(r, "ssh_get_authentication_socket"); 1843 return NULL; 1844 } 1845 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1846 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1847 debug_f("bound agent to hostkey"); 1848 else 1849 debug2_fr(r, "ssh_agent_bind_hostkey"); 1850 1851 c = channel_new(ssh, "agent-connection", 1852 SSH_CHANNEL_OPEN, sock, sock, -1, 1853 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1854 "authentication agent connection", 1); 1855 c->force_drain = 1; 1856 return c; 1857 } 1858 1859 char * 1860 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1861 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1862 { 1863 Channel *c; 1864 int r, fd; 1865 char *ifname = NULL; 1866 1867 if (tun_mode == SSH_TUNMODE_NO) 1868 return 0; 1869 1870 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1871 1872 /* Open local tunnel device */ 1873 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1874 error("Tunnel device open failed."); 1875 return NULL; 1876 } 1877 debug("Tunnel forwarding using interface %s", ifname); 1878 1879 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1880 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1881 c->datagram = 1; 1882 1883 #if defined(SSH_TUN_FILTER) 1884 if (options.tun_open == SSH_TUNMODE_POINTOPOINT) 1885 channel_register_filter(ssh, c->self, sys_tun_infilter, 1886 sys_tun_outfilter, NULL, NULL); 1887 #endif 1888 1889 if (cb != NULL) 1890 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1891 1892 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1893 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1894 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1895 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1896 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1897 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1898 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1899 (r = sshpkt_send(ssh)) != 0) 1900 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1901 1902 return ifname; 1903 } 1904 1905 /* XXXX move to generic input handler */ 1906 static int 1907 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1908 { 1909 Channel *c = NULL; 1910 char *ctype = NULL; 1911 int r; 1912 u_int rchan; 1913 size_t len; 1914 u_int rmaxpack, rwindow; 1915 1916 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1917 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1918 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1919 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1920 goto out; 1921 1922 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1923 ctype, rchan, rwindow, rmaxpack); 1924 1925 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1926 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1927 rmaxpack); 1928 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1929 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1930 } else if (strcmp(ctype, "x11") == 0) { 1931 c = client_request_x11(ssh, ctype, rchan); 1932 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1933 c = client_request_agent(ssh, ctype, rchan); 1934 } 1935 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1936 debug3("proxied to downstream: %s", ctype); 1937 } else if (c != NULL) { 1938 debug("confirm %s", ctype); 1939 c->remote_id = rchan; 1940 c->have_remote_id = 1; 1941 c->remote_window = rwindow; 1942 c->remote_maxpacket = rmaxpack; 1943 if (c->type != SSH_CHANNEL_CONNECTING) { 1944 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1945 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1946 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1947 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1948 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1949 (r = sshpkt_send(ssh)) != 0) 1950 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1951 } 1952 } else { 1953 debug("failure %s", ctype); 1954 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1955 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1956 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1957 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1958 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1959 (r = sshpkt_send(ssh)) != 0) 1960 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1961 } 1962 r = 0; 1963 out: 1964 free(ctype); 1965 return r; 1966 } 1967 1968 static int 1969 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1970 { 1971 Channel *c = NULL; 1972 char *rtype = NULL; 1973 u_char reply; 1974 u_int id, exitval; 1975 int r, success = 0; 1976 1977 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1978 return r; 1979 if (id <= INT_MAX) 1980 c = channel_lookup(ssh, id); 1981 if (channel_proxy_upstream(c, type, seq, ssh)) 1982 return 0; 1983 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1984 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1985 goto out; 1986 1987 debug("client_input_channel_req: channel %u rtype %s reply %d", 1988 id, rtype, reply); 1989 1990 if (c == NULL) { 1991 error("client_input_channel_req: channel %d: " 1992 "unknown channel", id); 1993 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 1994 if ((r = sshpkt_get_end(ssh)) != 0) 1995 goto out; 1996 chan_rcvd_eow(ssh, c); 1997 } else if (strcmp(rtype, "exit-status") == 0) { 1998 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 1999 goto out; 2000 if (c->ctl_chan != -1) { 2001 mux_exit_message(ssh, c, exitval); 2002 success = 1; 2003 } else if ((int)id == session_ident) { 2004 /* Record exit value of local session */ 2005 success = 1; 2006 exit_status = exitval; 2007 } else { 2008 /* Probably for a mux channel that has already closed */ 2009 debug_f("no sink for exit-status on channel %d", 2010 id); 2011 } 2012 if ((r = sshpkt_get_end(ssh)) != 0) 2013 goto out; 2014 } 2015 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 2016 if (!c->have_remote_id) 2017 fatal_f("channel %d: no remote_id", c->self); 2018 if ((r = sshpkt_start(ssh, success ? 2019 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2020 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2021 (r = sshpkt_send(ssh)) != 0) 2022 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2023 } 2024 r = 0; 2025 out: 2026 free(rtype); 2027 return r; 2028 } 2029 2030 struct hostkeys_update_ctx { 2031 /* The hostname and (optionally) IP address string for the server */ 2032 char *host_str, *ip_str; 2033 2034 /* 2035 * Keys received from the server and a flag for each indicating 2036 * whether they already exist in known_hosts. 2037 * keys_match is filled in by hostkeys_find() and later (for new 2038 * keys) by client_global_hostkeys_prove_confirm(). 2039 */ 2040 struct sshkey **keys; 2041 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2042 int *keys_verified; /* flag for new keys verified by server */ 2043 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2044 2045 /* 2046 * Keys that are in known_hosts, but were not present in the update 2047 * from the server (i.e. scheduled to be deleted). 2048 * Filled in by hostkeys_find(). 2049 */ 2050 struct sshkey **old_keys; 2051 size_t nold; 2052 2053 /* Various special cases. */ 2054 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2055 int ca_available; /* saw CA key for this host */ 2056 int old_key_seen; /* saw old key with other name/addr */ 2057 int other_name_seen; /* saw key with other name/addr */ 2058 }; 2059 2060 static void 2061 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2062 { 2063 size_t i; 2064 2065 if (ctx == NULL) 2066 return; 2067 for (i = 0; i < ctx->nkeys; i++) 2068 sshkey_free(ctx->keys[i]); 2069 free(ctx->keys); 2070 free(ctx->keys_match); 2071 free(ctx->keys_verified); 2072 for (i = 0; i < ctx->nold; i++) 2073 sshkey_free(ctx->old_keys[i]); 2074 free(ctx->old_keys); 2075 free(ctx->host_str); 2076 free(ctx->ip_str); 2077 free(ctx); 2078 } 2079 2080 /* 2081 * Returns non-zero if a known_hosts hostname list is not of a form that 2082 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2083 * hostnames lists that do not follow the form host[,ip]. 2084 */ 2085 static int 2086 hostspec_is_complex(const char *hosts) 2087 { 2088 char *cp; 2089 2090 /* wildcard */ 2091 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2092 return 1; 2093 /* single host/ip = ok */ 2094 if ((cp = strchr(hosts, ',')) == NULL) 2095 return 0; 2096 /* more than two entries on the line */ 2097 if (strchr(cp + 1, ',') != NULL) 2098 return 1; 2099 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2100 return 0; 2101 } 2102 2103 /* callback to search for ctx->keys in known_hosts */ 2104 static int 2105 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2106 { 2107 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2108 size_t i; 2109 struct sshkey **tmp; 2110 2111 if (l->key == NULL) 2112 return 0; 2113 if (l->status != HKF_STATUS_MATCHED) { 2114 /* Record if one of the keys appears on a non-matching line */ 2115 for (i = 0; i < ctx->nkeys; i++) { 2116 if (sshkey_equal(l->key, ctx->keys[i])) { 2117 ctx->other_name_seen = 1; 2118 debug3_f("found %s key under different " 2119 "name/addr at %s:%ld", 2120 sshkey_ssh_name(ctx->keys[i]), 2121 l->path, l->linenum); 2122 return 0; 2123 } 2124 } 2125 return 0; 2126 } 2127 /* Don't proceed if revocation or CA markers are present */ 2128 /* XXX relax this */ 2129 if (l->marker != MRK_NONE) { 2130 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2131 l->path, l->linenum); 2132 ctx->complex_hostspec = 1; 2133 return 0; 2134 } 2135 2136 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2137 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2138 if ((l->match & HKF_MATCH_HOST) == 0) { 2139 /* Record if address matched a different hostname. */ 2140 ctx->other_name_seen = 1; 2141 debug3_f("found address %s against different hostname " 2142 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2143 return 0; 2144 } else if ((l->match & HKF_MATCH_IP) == 0) { 2145 /* Record if hostname matched a different address. */ 2146 ctx->other_name_seen = 1; 2147 debug3_f("found hostname %s against different address " 2148 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2149 } 2150 } 2151 2152 /* 2153 * UpdateHostkeys is skipped for wildcard host names and hostnames 2154 * that contain more than two entries (ssh never writes these). 2155 */ 2156 if (hostspec_is_complex(l->hosts)) { 2157 debug3_f("hostkeys file %s:%ld complex host specification", 2158 l->path, l->linenum); 2159 ctx->complex_hostspec = 1; 2160 return 0; 2161 } 2162 2163 /* Mark off keys we've already seen for this host */ 2164 for (i = 0; i < ctx->nkeys; i++) { 2165 if (!sshkey_equal(l->key, ctx->keys[i])) 2166 continue; 2167 debug3_f("found %s key at %s:%ld", 2168 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2169 ctx->keys_match[i] |= l->match; 2170 return 0; 2171 } 2172 /* This line contained a key that not offered by the server */ 2173 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2174 l->path, l->linenum); 2175 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2176 sizeof(*ctx->old_keys))) == NULL) 2177 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2178 ctx->old_keys = tmp; 2179 ctx->old_keys[ctx->nold++] = l->key; 2180 l->key = NULL; 2181 2182 return 0; 2183 } 2184 2185 /* callback to search for ctx->old_keys in known_hosts under other names */ 2186 static int 2187 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2188 { 2189 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2190 size_t i; 2191 int hashed; 2192 2193 /* only care about lines that *don't* match the active host spec */ 2194 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2195 return 0; 2196 2197 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2198 for (i = 0; i < ctx->nold; i++) { 2199 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2200 continue; 2201 debug3_f("found deprecated %s key at %s:%ld as %s", 2202 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2203 hashed ? "[HASHED]" : l->hosts); 2204 ctx->old_key_seen = 1; 2205 break; 2206 } 2207 return 0; 2208 } 2209 2210 /* 2211 * Check known_hosts files for deprecated keys under other names. Returns 0 2212 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2213 * exist under names other than the active hostname/IP. 2214 */ 2215 static int 2216 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2217 { 2218 size_t i; 2219 int r; 2220 2221 debug2_f("checking for %zu deprecated keys", ctx->nold); 2222 for (i = 0; i < options.num_user_hostfiles; i++) { 2223 debug3_f("searching %s for %s / %s", 2224 options.user_hostfiles[i], ctx->host_str, 2225 ctx->ip_str ? ctx->ip_str : "(none)"); 2226 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2227 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2228 HKF_WANT_PARSE_KEY, 0)) != 0) { 2229 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2230 debug_f("hostkeys file %s does not exist", 2231 options.user_hostfiles[i]); 2232 continue; 2233 } 2234 error_fr(r, "hostkeys_foreach failed for %s", 2235 options.user_hostfiles[i]); 2236 return -1; 2237 } 2238 } 2239 return 0; 2240 } 2241 2242 static void 2243 hostkey_change_preamble(LogLevel loglevel) 2244 { 2245 do_log2(loglevel, "The server has updated its host keys."); 2246 do_log2(loglevel, "These changes were verified by the server's " 2247 "existing trusted key."); 2248 } 2249 2250 static void 2251 update_known_hosts(struct hostkeys_update_ctx *ctx) 2252 { 2253 int r, was_raw = 0, first = 1; 2254 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2255 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2256 char *fp, *response; 2257 size_t i; 2258 struct stat sb; 2259 2260 for (i = 0; i < ctx->nkeys; i++) { 2261 if (!ctx->keys_verified[i]) 2262 continue; 2263 if ((fp = sshkey_fingerprint(ctx->keys[i], 2264 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2265 fatal_f("sshkey_fingerprint failed"); 2266 if (first && asking) 2267 hostkey_change_preamble(loglevel); 2268 do_log2(loglevel, "Learned new hostkey: %s %s", 2269 sshkey_type(ctx->keys[i]), fp); 2270 first = 0; 2271 free(fp); 2272 } 2273 for (i = 0; i < ctx->nold; i++) { 2274 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2275 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2276 fatal_f("sshkey_fingerprint failed"); 2277 if (first && asking) 2278 hostkey_change_preamble(loglevel); 2279 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2280 sshkey_type(ctx->old_keys[i]), fp); 2281 first = 0; 2282 free(fp); 2283 } 2284 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2285 if (get_saved_tio() != NULL) { 2286 leave_raw_mode(1); 2287 was_raw = 1; 2288 } 2289 response = NULL; 2290 for (i = 0; !quit_pending && i < 3; i++) { 2291 free(response); 2292 response = read_passphrase("Accept updated hostkeys? " 2293 "(yes/no): ", RP_ECHO); 2294 if (response != NULL && strcasecmp(response, "yes") == 0) 2295 break; 2296 else if (quit_pending || response == NULL || 2297 strcasecmp(response, "no") == 0) { 2298 options.update_hostkeys = 0; 2299 break; 2300 } else { 2301 do_log2(loglevel, "Please enter " 2302 "\"yes\" or \"no\""); 2303 } 2304 } 2305 if (quit_pending || i >= 3 || response == NULL) 2306 options.update_hostkeys = 0; 2307 free(response); 2308 if (was_raw) 2309 enter_raw_mode(1); 2310 } 2311 if (options.update_hostkeys == 0) 2312 return; 2313 /* 2314 * Now that all the keys are verified, we can go ahead and replace 2315 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2316 * cancel the operation). 2317 */ 2318 for (i = 0; i < options.num_user_hostfiles; i++) { 2319 /* 2320 * NB. keys are only added to hostfiles[0], for the rest we 2321 * just delete the hostname entries. 2322 */ 2323 if (stat(options.user_hostfiles[i], &sb) != 0) { 2324 if (errno == ENOENT) { 2325 debug_f("known hosts file %s does not " 2326 "exist", options.user_hostfiles[i]); 2327 } else { 2328 error_f("known hosts file %s " 2329 "inaccessible: %s", 2330 options.user_hostfiles[i], strerror(errno)); 2331 } 2332 continue; 2333 } 2334 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2335 ctx->host_str, ctx->ip_str, 2336 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2337 options.hash_known_hosts, 0, 2338 options.fingerprint_hash)) != 0) { 2339 error_fr(r, "hostfile_replace_entries failed for %s", 2340 options.user_hostfiles[i]); 2341 } 2342 } 2343 } 2344 2345 static void 2346 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2347 u_int32_t seq, void *_ctx) 2348 { 2349 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2350 size_t i, ndone; 2351 struct sshbuf *signdata; 2352 int r, plaintype; 2353 const u_char *sig; 2354 const char *rsa_kexalg = NULL; 2355 char *alg = NULL; 2356 size_t siglen; 2357 2358 if (ctx->nnew == 0) 2359 fatal_f("ctx->nnew == 0"); /* sanity */ 2360 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2361 error("Server failed to confirm ownership of " 2362 "private host keys"); 2363 hostkeys_update_ctx_free(ctx); 2364 return; 2365 } 2366 if (sshkey_type_plain(sshkey_type_from_name( 2367 ssh->kex->hostkey_alg)) == KEY_RSA) 2368 rsa_kexalg = ssh->kex->hostkey_alg; 2369 if ((signdata = sshbuf_new()) == NULL) 2370 fatal_f("sshbuf_new failed"); 2371 /* 2372 * Expect a signature for each of the ctx->nnew private keys we 2373 * haven't seen before. They will be in the same order as the 2374 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2375 */ 2376 for (ndone = i = 0; i < ctx->nkeys; i++) { 2377 if (ctx->keys_match[i]) 2378 continue; 2379 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2380 /* Prepare data to be signed: session ID, unique string, key */ 2381 sshbuf_reset(signdata); 2382 if ( (r = sshbuf_put_cstring(signdata, 2383 "hostkeys-prove-00@openssh.com")) != 0 || 2384 (r = sshbuf_put_stringb(signdata, 2385 ssh->kex->session_id)) != 0 || 2386 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2387 fatal_fr(r, "compose signdata"); 2388 /* Extract and verify signature */ 2389 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2390 error_fr(r, "parse sig"); 2391 goto out; 2392 } 2393 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2394 error_fr(r, "server gave unintelligible signature " 2395 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2396 goto out; 2397 } 2398 /* 2399 * Special case for RSA keys: if a RSA hostkey was negotiated, 2400 * then use its signature type for verification of RSA hostkey 2401 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2402 */ 2403 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2404 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2405 debug_f("server used untrusted RSA signature algorithm " 2406 "%s for key %zu, disregarding", alg, i); 2407 free(alg); 2408 /* zap the key from the list */ 2409 sshkey_free(ctx->keys[i]); 2410 ctx->keys[i] = NULL; 2411 ndone++; 2412 continue; 2413 } 2414 debug3_f("verify %s key %zu using sigalg %s", 2415 sshkey_type(ctx->keys[i]), i, alg); 2416 free(alg); 2417 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2418 sshbuf_ptr(signdata), sshbuf_len(signdata), 2419 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2420 error_fr(r, "server gave bad signature for %s key %zu", 2421 sshkey_type(ctx->keys[i]), i); 2422 goto out; 2423 } 2424 /* Key is good. Mark it as 'seen' */ 2425 ctx->keys_verified[i] = 1; 2426 ndone++; 2427 } 2428 /* Shouldn't happen */ 2429 if (ndone != ctx->nnew) 2430 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2431 if ((r = sshpkt_get_end(ssh)) != 0) { 2432 error_f("protocol error"); 2433 goto out; 2434 } 2435 2436 /* Make the edits to known_hosts */ 2437 update_known_hosts(ctx); 2438 out: 2439 hostkeys_update_ctx_free(ctx); 2440 hostkeys_update_complete = 1; 2441 client_repledge(); 2442 } 2443 2444 /* 2445 * Returns non-zero if the key is accepted by HostkeyAlgorithms. 2446 * Made slightly less trivial by the multiple RSA signature algorithm names. 2447 */ 2448 static int 2449 key_accepted_by_hostkeyalgs(const struct sshkey *key) 2450 { 2451 const char *ktype = sshkey_ssh_name(key); 2452 const char *hostkeyalgs = options.hostkeyalgorithms; 2453 2454 if (key->type == KEY_UNSPEC) 2455 return 0; 2456 if (key->type == KEY_RSA && 2457 (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 || 2458 match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1)) 2459 return 1; 2460 return match_pattern_list(ktype, hostkeyalgs, 0) == 1; 2461 } 2462 2463 /* 2464 * Handle hostkeys-00@openssh.com global request to inform the client of all 2465 * the server's hostkeys. The keys are checked against the user's 2466 * HostkeyAlgorithms preference before they are accepted. 2467 */ 2468 static int 2469 client_input_hostkeys(struct ssh *ssh) 2470 { 2471 const u_char *blob = NULL; 2472 size_t i, len = 0; 2473 struct sshbuf *buf = NULL; 2474 struct sshkey *key = NULL, **tmp; 2475 int r, prove_sent = 0; 2476 char *fp; 2477 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2478 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2479 struct hostkeys_update_ctx *ctx = NULL; 2480 u_int want; 2481 2482 if (hostkeys_seen) 2483 fatal_f("server already sent hostkeys"); 2484 if (!can_update_hostkeys()) 2485 return 1; 2486 hostkeys_seen = 1; 2487 2488 ctx = xcalloc(1, sizeof(*ctx)); 2489 while (ssh_packet_remaining(ssh) > 0) { 2490 sshkey_free(key); 2491 key = NULL; 2492 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2493 error_fr(r, "parse key"); 2494 goto out; 2495 } 2496 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2497 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2498 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2499 "convert key"); 2500 continue; 2501 } 2502 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2503 SSH_FP_DEFAULT); 2504 debug3_f("received %s key %s", sshkey_type(key), fp); 2505 free(fp); 2506 2507 if (!key_accepted_by_hostkeyalgs(key)) { 2508 debug3_f("%s key not permitted by " 2509 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2510 continue; 2511 } 2512 /* Skip certs */ 2513 if (sshkey_is_cert(key)) { 2514 debug3_f("%s key is a certificate; skipping", 2515 sshkey_ssh_name(key)); 2516 continue; 2517 } 2518 /* Ensure keys are unique */ 2519 for (i = 0; i < ctx->nkeys; i++) { 2520 if (sshkey_equal(key, ctx->keys[i])) { 2521 error_f("received duplicated %s host key", 2522 sshkey_ssh_name(key)); 2523 goto out; 2524 } 2525 } 2526 /* Key is good, record it */ 2527 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2528 sizeof(*ctx->keys))) == NULL) 2529 fatal_f("recallocarray failed nkeys = %zu", 2530 ctx->nkeys); 2531 ctx->keys = tmp; 2532 ctx->keys[ctx->nkeys++] = key; 2533 key = NULL; 2534 } 2535 2536 if (ctx->nkeys == 0) { 2537 debug_f("server sent no hostkeys"); 2538 goto out; 2539 } 2540 2541 if ((ctx->keys_match = calloc(ctx->nkeys, 2542 sizeof(*ctx->keys_match))) == NULL || 2543 (ctx->keys_verified = calloc(ctx->nkeys, 2544 sizeof(*ctx->keys_verified))) == NULL) 2545 fatal_f("calloc failed"); 2546 2547 get_hostfile_hostname_ipaddr(host, 2548 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2549 options.port, &ctx->host_str, 2550 options.check_host_ip ? &ctx->ip_str : NULL); 2551 2552 /* Find which keys we already know about. */ 2553 for (i = 0; i < options.num_user_hostfiles; i++) { 2554 debug_f("searching %s for %s / %s", 2555 options.user_hostfiles[i], ctx->host_str, 2556 ctx->ip_str ? ctx->ip_str : "(none)"); 2557 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2558 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2559 HKF_WANT_PARSE_KEY, 0)) != 0) { 2560 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2561 debug_f("hostkeys file %s does not exist", 2562 options.user_hostfiles[i]); 2563 continue; 2564 } 2565 error_fr(r, "hostkeys_foreach failed for %s", 2566 options.user_hostfiles[i]); 2567 goto out; 2568 } 2569 } 2570 2571 /* Figure out if we have any new keys to add */ 2572 ctx->nnew = ctx->nincomplete = 0; 2573 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2574 for (i = 0; i < ctx->nkeys; i++) { 2575 if (ctx->keys_match[i] == 0) 2576 ctx->nnew++; 2577 if ((ctx->keys_match[i] & want) != want) 2578 ctx->nincomplete++; 2579 } 2580 2581 debug3_f("%zu server keys: %zu new, %zu retained, " 2582 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2583 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2584 ctx->nincomplete, ctx->nold); 2585 2586 if (ctx->nnew == 0 && ctx->nold == 0) { 2587 debug_f("no new or deprecated keys from server"); 2588 goto out; 2589 } 2590 2591 /* Various reasons why we cannot proceed with the update */ 2592 if (ctx->complex_hostspec) { 2593 debug_f("CA/revocation marker, manual host list or wildcard " 2594 "host pattern found, skipping UserKnownHostsFile update"); 2595 goto out; 2596 } 2597 if (ctx->other_name_seen) { 2598 debug_f("host key found matching a different name/address, " 2599 "skipping UserKnownHostsFile update"); 2600 goto out; 2601 } 2602 /* 2603 * If removing keys, check whether they appear under different 2604 * names/addresses and refuse to proceed if they do. This avoids 2605 * cases such as hosts with multiple names becoming inconsistent 2606 * with regards to CheckHostIP entries. 2607 * XXX UpdateHostkeys=force to override this (and other) checks? 2608 */ 2609 if (ctx->nold != 0) { 2610 if (check_old_keys_othernames(ctx) != 0) 2611 goto out; /* error already logged */ 2612 if (ctx->old_key_seen) { 2613 debug_f("key(s) for %s%s%s exist under other names; " 2614 "skipping UserKnownHostsFile update", 2615 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2616 ctx->ip_str == NULL ? "" : ctx->ip_str); 2617 goto out; 2618 } 2619 } 2620 2621 if (ctx->nnew == 0) { 2622 /* 2623 * We have some keys to remove or fix matching for. 2624 * We can proceed to do this without requiring a fresh proof 2625 * from the server. 2626 */ 2627 update_known_hosts(ctx); 2628 goto out; 2629 } 2630 /* 2631 * We have received previously-unseen keys from the server. 2632 * Ask the server to confirm ownership of the private halves. 2633 */ 2634 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2635 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2636 (r = sshpkt_put_cstring(ssh, 2637 "hostkeys-prove-00@openssh.com")) != 0 || 2638 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2639 fatal_fr(r, "prepare hostkeys-prove"); 2640 if ((buf = sshbuf_new()) == NULL) 2641 fatal_f("sshbuf_new"); 2642 for (i = 0; i < ctx->nkeys; i++) { 2643 if (ctx->keys_match[i]) 2644 continue; 2645 sshbuf_reset(buf); 2646 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2647 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2648 fatal_fr(r, "assemble hostkeys-prove"); 2649 } 2650 if ((r = sshpkt_send(ssh)) != 0) 2651 fatal_fr(r, "send hostkeys-prove"); 2652 client_register_global_confirm( 2653 client_global_hostkeys_prove_confirm, ctx); 2654 ctx = NULL; /* will be freed in callback */ 2655 prove_sent = 1; 2656 2657 /* Success */ 2658 out: 2659 hostkeys_update_ctx_free(ctx); 2660 sshkey_free(key); 2661 sshbuf_free(buf); 2662 if (!prove_sent) { 2663 /* UpdateHostkeys handling completed */ 2664 hostkeys_update_complete = 1; 2665 client_repledge(); 2666 } 2667 /* 2668 * NB. Return success for all cases. The server doesn't need to know 2669 * what the client does with its hosts file. 2670 */ 2671 return 1; 2672 } 2673 2674 static int 2675 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2676 { 2677 char *rtype; 2678 u_char want_reply; 2679 int r, success = 0; 2680 2681 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2682 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2683 goto out; 2684 debug("client_input_global_request: rtype %s want_reply %d", 2685 rtype, want_reply); 2686 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2687 success = client_input_hostkeys(ssh); 2688 if (want_reply) { 2689 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2690 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2691 (r = sshpkt_send(ssh)) != 0 || 2692 (r = ssh_packet_write_wait(ssh)) != 0) 2693 goto out; 2694 } 2695 r = 0; 2696 out: 2697 free(rtype); 2698 return r; 2699 } 2700 2701 static void 2702 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2703 { 2704 int r; 2705 2706 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2707 channel_request_start(ssh, id, "env", 0); 2708 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2709 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2710 (r = sshpkt_send(ssh)) != 0) 2711 fatal_fr(r, "send setenv"); 2712 } 2713 2714 void 2715 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2716 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2717 char **env) 2718 { 2719 size_t i, j, len; 2720 int matched, r; 2721 char *name, *val; 2722 Channel *c = NULL; 2723 2724 debug2_f("id %d", id); 2725 2726 if ((c = channel_lookup(ssh, id)) == NULL) 2727 fatal_f("channel %d: unknown channel", id); 2728 2729 ssh_packet_set_interactive(ssh, want_tty, 2730 options.ip_qos_interactive, options.ip_qos_bulk); 2731 2732 if (want_tty) { 2733 struct winsize ws; 2734 2735 /* Store window size in the packet. */ 2736 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2737 memset(&ws, 0, sizeof(ws)); 2738 2739 channel_request_start(ssh, id, "pty-req", 1); 2740 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2741 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2742 != 0 || 2743 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2744 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2745 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2746 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2747 fatal_fr(r, "build pty-req"); 2748 if (tiop == NULL) 2749 tiop = get_saved_tio(); 2750 ssh_tty_make_modes(ssh, -1, tiop); 2751 if ((r = sshpkt_send(ssh)) != 0) 2752 fatal_fr(r, "send pty-req"); 2753 /* XXX wait for reply */ 2754 c->client_tty = 1; 2755 } 2756 2757 /* Transfer any environment variables from client to server */ 2758 if (options.num_send_env != 0 && env != NULL) { 2759 debug("Sending environment."); 2760 for (i = 0; env[i] != NULL; i++) { 2761 /* Split */ 2762 name = xstrdup(env[i]); 2763 if ((val = strchr(name, '=')) == NULL) { 2764 free(name); 2765 continue; 2766 } 2767 *val++ = '\0'; 2768 2769 matched = 0; 2770 for (j = 0; j < options.num_send_env; j++) { 2771 if (match_pattern(name, options.send_env[j])) { 2772 matched = 1; 2773 break; 2774 } 2775 } 2776 if (!matched) { 2777 debug3("Ignored env %s", name); 2778 free(name); 2779 continue; 2780 } 2781 client_send_env(ssh, id, name, val); 2782 free(name); 2783 } 2784 } 2785 for (i = 0; i < options.num_setenv; i++) { 2786 /* Split */ 2787 name = xstrdup(options.setenv[i]); 2788 if ((val = strchr(name, '=')) == NULL) { 2789 free(name); 2790 continue; 2791 } 2792 *val++ = '\0'; 2793 client_send_env(ssh, id, name, val); 2794 free(name); 2795 } 2796 2797 len = sshbuf_len(cmd); 2798 if (len > 0) { 2799 if (len > 900) 2800 len = 900; 2801 if (want_subsystem) { 2802 debug("Sending subsystem: %.*s", 2803 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2804 channel_request_start(ssh, id, "subsystem", 1); 2805 client_expect_confirm(ssh, id, "subsystem", 2806 CONFIRM_CLOSE); 2807 } else { 2808 debug("Sending command: %.*s", 2809 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2810 channel_request_start(ssh, id, "exec", 1); 2811 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2812 } 2813 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2814 (r = sshpkt_send(ssh)) != 0) 2815 fatal_fr(r, "send command"); 2816 } else { 2817 channel_request_start(ssh, id, "shell", 1); 2818 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2819 if ((r = sshpkt_send(ssh)) != 0) 2820 fatal_fr(r, "send shell"); 2821 } 2822 2823 session_setup_complete = 1; 2824 client_repledge(); 2825 } 2826 2827 static void 2828 client_init_dispatch(struct ssh *ssh) 2829 { 2830 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2831 2832 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2833 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2834 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2835 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2836 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2837 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2838 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2839 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2840 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2841 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2842 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2843 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2844 2845 /* rekeying */ 2846 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2847 2848 /* global request reply messages */ 2849 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2850 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2851 } 2852 2853 void 2854 client_stop_mux(void) 2855 { 2856 if (options.control_path != NULL && muxserver_sock != -1) 2857 unlink(options.control_path); 2858 /* 2859 * If we are in persist mode, or don't have a shell, signal that we 2860 * should close when all active channels are closed. 2861 */ 2862 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2863 session_closed = 1; 2864 setproctitle("[stopped mux]"); 2865 } 2866 } 2867 2868 /* client specific fatal cleanup */ 2869 void 2870 cleanup_exit(int i) 2871 { 2872 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2873 if (options.control_path != NULL && muxserver_sock != -1) 2874 unlink(options.control_path); 2875 ssh_kill_proxy_command(); 2876 _exit(i); 2877 } 2878