1 /* $NetBSD: clientloop.c,v 1.40 2024/06/25 16:36:54 christos Exp $ */ 2 /* $OpenBSD: clientloop.c,v 1.403 2024/02/21 05:57:34 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * The main loop for the interactive session (client side). 9 * 10 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 * 16 * 17 * Copyright (c) 1999 Theo de Raadt. All rights reserved. 18 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 1. Redistributions of source code must retain the above copyright 23 * notice, this list of conditions and the following disclaimer. 24 * 2. Redistributions in binary form must reproduce the above copyright 25 * notice, this list of conditions and the following disclaimer in the 26 * documentation and/or other materials provided with the distribution. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 38 * 39 * 40 * SSH2 support added by Markus Friedl. 41 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 52 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 53 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 54 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 55 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 56 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 57 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 58 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 59 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 60 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 61 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 62 */ 63 64 #include "includes.h" 65 __RCSID("$NetBSD: clientloop.c,v 1.40 2024/06/25 16:36:54 christos Exp $"); 66 67 #include <sys/types.h> 68 #include <sys/ioctl.h> 69 #include <sys/stat.h> 70 #include <sys/socket.h> 71 #include <sys/time.h> 72 #include <sys/queue.h> 73 74 #include <ctype.h> 75 #include <errno.h> 76 #include <paths.h> 77 #include <poll.h> 78 #include <signal.h> 79 #include <stdio.h> 80 #include <stdlib.h> 81 #include <string.h> 82 #include <stdarg.h> 83 #include <termios.h> 84 #include <pwd.h> 85 #include <unistd.h> 86 #include <limits.h> 87 88 #include "xmalloc.h" 89 #include "ssh.h" 90 #include "ssh2.h" 91 #include "packet.h" 92 #include "sshbuf.h" 93 #include "compat.h" 94 #include "channels.h" 95 #include "dispatch.h" 96 #include "sshkey.h" 97 #include "cipher.h" 98 #include "kex.h" 99 #include "myproposal.h" 100 #include "log.h" 101 #include "misc.h" 102 #include "readconf.h" 103 #include "clientloop.h" 104 #include "sshconnect.h" 105 #include "authfd.h" 106 #include "atomicio.h" 107 #include "sshpty.h" 108 #include "match.h" 109 #include "msg.h" 110 #include "getpeereid.h" 111 #include "ssherr.h" 112 #include "hostfile.h" 113 114 /* Permitted RSA signature algorithms for UpdateHostkeys proofs */ 115 #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256" 116 117 /* Uncertainty (in percent) of keystroke timing intervals */ 118 #define SSH_KEYSTROKE_TIMING_FUZZ 10 119 120 /* import options */ 121 extern Options options; 122 123 /* Control socket */ 124 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */ 125 126 /* 127 * Name of the host we are connecting to. This is the name given on the 128 * command line, or the Hostname specified for the user-supplied name in a 129 * configuration file. 130 */ 131 extern char *host; 132 133 /* 134 * If this field is not NULL, the ForwardAgent socket is this path and different 135 * instead of SSH_AUTH_SOCK. 136 */ 137 extern char *forward_agent_sock_path; 138 139 /* 140 * Flag to indicate that we have received a window change signal which has 141 * not yet been processed. This will cause a message indicating the new 142 * window size to be sent to the server a little later. This is volatile 143 * because this is updated in a signal handler. 144 */ 145 static volatile sig_atomic_t received_window_change_signal = 0; 146 static volatile sig_atomic_t received_signal = 0; 147 148 /* Time when backgrounded control master using ControlPersist should exit */ 149 static time_t control_persist_exit_time = 0; 150 151 /* Common data for the client loop code. */ 152 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ 153 static int last_was_cr; /* Last character was a newline. */ 154 static int exit_status; /* Used to store the command exit status. */ 155 static struct sshbuf *stderr_buffer; /* Used for final exit message. */ 156 static int connection_in; /* Connection to server (input). */ 157 static int connection_out; /* Connection to server (output). */ 158 static int need_rekeying; /* Set to non-zero if rekeying is requested. */ 159 static int session_closed; /* In SSH2: login session closed. */ 160 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */ 161 static time_t server_alive_time; /* Time to do server_alive_check */ 162 static int hostkeys_update_complete; 163 static int session_setup_complete; 164 165 static void client_init_dispatch(struct ssh *ssh); 166 int session_ident = -1; 167 168 /* Track escape per proto2 channel */ 169 struct escape_filter_ctx { 170 int escape_pending; 171 int escape_char; 172 }; 173 174 /* Context for channel confirmation replies */ 175 struct channel_reply_ctx { 176 const char *request_type; 177 int id; 178 enum confirm_action action; 179 }; 180 181 /* Global request success/failure callbacks */ 182 /* XXX move to struct ssh? */ 183 struct global_confirm { 184 TAILQ_ENTRY(global_confirm) entry; 185 global_confirm_cb *cb; 186 void *ctx; 187 int ref_count; 188 }; 189 TAILQ_HEAD(global_confirms, global_confirm); 190 static struct global_confirms global_confirms = 191 TAILQ_HEAD_INITIALIZER(global_confirms); 192 193 void ssh_process_session2_setup(int, int, int, struct sshbuf *); 194 static void quit_message(const char *fmt, ...) 195 __attribute__((__format__ (printf, 1, 2))); 196 197 static void 198 quit_message(const char *fmt, ...) 199 { 200 char *msg; 201 va_list args; 202 int r; 203 204 va_start(args, fmt); 205 xvasprintf(&msg, fmt, args); 206 va_end(args); 207 208 if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0) 209 fatal_fr(r, "sshbuf_putf"); 210 free(msg); 211 quit_pending = 1; 212 } 213 214 /* 215 * Signal handler for the window change signal (SIGWINCH). This just sets a 216 * flag indicating that the window has changed. 217 */ 218 static void 219 window_change_handler(int sig) 220 { 221 received_window_change_signal = 1; 222 } 223 224 /* 225 * Signal handler for signals that cause the program to terminate. These 226 * signals must be trapped to restore terminal modes. 227 */ 228 static void 229 signal_handler(int sig) 230 { 231 received_signal = sig; 232 quit_pending = 1; 233 } 234 235 /* 236 * Sets control_persist_exit_time to the absolute time when the 237 * backgrounded control master should exit due to expiry of the 238 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded 239 * control master process, or if there is no ControlPersist timeout. 240 */ 241 static void 242 set_control_persist_exit_time(struct ssh *ssh) 243 { 244 if (muxserver_sock == -1 || !options.control_persist 245 || options.control_persist_timeout == 0) { 246 /* not using a ControlPersist timeout */ 247 control_persist_exit_time = 0; 248 } else if (channel_still_open(ssh)) { 249 /* some client connections are still open */ 250 if (control_persist_exit_time > 0) 251 debug2_f("cancel scheduled exit"); 252 control_persist_exit_time = 0; 253 } else if (control_persist_exit_time <= 0) { 254 /* a client connection has recently closed */ 255 control_persist_exit_time = monotime() + 256 (time_t)options.control_persist_timeout; 257 debug2_f("schedule exit in %d seconds", 258 options.control_persist_timeout); 259 } 260 /* else we are already counting down to the timeout */ 261 } 262 263 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_" 264 static int 265 client_x11_display_valid(const char *display) 266 { 267 size_t i, dlen; 268 269 if (display == NULL) 270 return 0; 271 272 dlen = strlen(display); 273 for (i = 0; i < dlen; i++) { 274 if (!isalnum((u_char)display[i]) && 275 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) { 276 debug("Invalid character '%c' in DISPLAY", display[i]); 277 return 0; 278 } 279 } 280 return 1; 281 } 282 283 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1" 284 #define X11_TIMEOUT_SLACK 60 285 int 286 client_x11_get_proto(struct ssh *ssh, const char *display, 287 const char *xauth_path, u_int trusted, u_int timeout, 288 char **_proto, char **_data) 289 { 290 char *cmd, line[512], xdisplay[512]; 291 char xauthfile[PATH_MAX], xauthdir[PATH_MAX]; 292 static char proto[512], data[512]; 293 FILE *f; 294 int got_data = 0, generated = 0, do_unlink = 0, r; 295 struct stat st; 296 u_int now, x11_timeout_real; 297 298 *_proto = proto; 299 *_data = data; 300 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0'; 301 302 if (!client_x11_display_valid(display)) { 303 if (display != NULL) 304 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding", 305 display); 306 return -1; 307 } 308 if (xauth_path != NULL && stat(xauth_path, &st) == -1) { 309 debug("No xauth program."); 310 xauth_path = NULL; 311 } 312 313 if (xauth_path != NULL) { 314 /* 315 * Handle FamilyLocal case where $DISPLAY does 316 * not match an authorization entry. For this we 317 * just try "xauth list unix:displaynum.screennum". 318 * XXX: "localhost" match to determine FamilyLocal 319 * is not perfect. 320 */ 321 if (strncmp(display, "localhost:", 10) == 0) { 322 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s", 323 display + 10)) < 0 || 324 (size_t)r >= sizeof(xdisplay)) { 325 error_f("display name too long"); 326 return -1; 327 } 328 display = xdisplay; 329 } 330 if (trusted == 0) { 331 /* 332 * Generate an untrusted X11 auth cookie. 333 * 334 * The authentication cookie should briefly outlive 335 * ssh's willingness to forward X11 connections to 336 * avoid nasty fail-open behaviour in the X server. 337 */ 338 mktemp_proto(xauthdir, sizeof(xauthdir)); 339 if (mkdtemp(xauthdir) == NULL) { 340 error_f("mkdtemp: %s", strerror(errno)); 341 return -1; 342 } 343 do_unlink = 1; 344 if ((r = snprintf(xauthfile, sizeof(xauthfile), 345 "%s/xauthfile", xauthdir)) < 0 || 346 (size_t)r >= sizeof(xauthfile)) { 347 error_f("xauthfile path too long"); 348 rmdir(xauthdir); 349 return -1; 350 } 351 352 if (timeout == 0) { 353 /* auth doesn't time out */ 354 xasprintf(&cmd, "%s -f %s generate %s %s " 355 "untrusted 2>%s", 356 xauth_path, xauthfile, display, 357 SSH_X11_PROTO, _PATH_DEVNULL); 358 } else { 359 /* Add some slack to requested expiry */ 360 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK) 361 x11_timeout_real = timeout + 362 X11_TIMEOUT_SLACK; 363 else { 364 /* Don't overflow on long timeouts */ 365 x11_timeout_real = UINT_MAX; 366 } 367 xasprintf(&cmd, "%s -f %s generate %s %s " 368 "untrusted timeout %u 2>%s", 369 xauth_path, xauthfile, display, 370 SSH_X11_PROTO, x11_timeout_real, 371 _PATH_DEVNULL); 372 } 373 debug2_f("xauth command: %s", cmd); 374 375 if (timeout != 0 && x11_refuse_time == 0) { 376 now = monotime() + 1; 377 if (SSH_TIME_T_MAX - timeout < now) 378 x11_refuse_time = SSH_TIME_T_MAX; 379 else 380 x11_refuse_time = now + timeout; 381 channel_set_x11_refuse_time(ssh, 382 x11_refuse_time); 383 } 384 if (system(cmd) == 0) 385 generated = 1; 386 free(cmd); 387 } 388 389 /* 390 * When in untrusted mode, we read the cookie only if it was 391 * successfully generated as an untrusted one in the step 392 * above. 393 */ 394 if (trusted || generated) { 395 xasprintf(&cmd, 396 "%s %s%s list %s 2>" _PATH_DEVNULL, 397 xauth_path, 398 generated ? "-f " : "" , 399 generated ? xauthfile : "", 400 display); 401 debug2("x11_get_proto: %s", cmd); 402 f = popen(cmd, "r"); 403 if (f && fgets(line, sizeof(line), f) && 404 sscanf(line, "%*s %511s %511s", proto, data) == 2) 405 got_data = 1; 406 if (f) 407 pclose(f); 408 free(cmd); 409 } 410 } 411 412 if (do_unlink) { 413 unlink(xauthfile); 414 rmdir(xauthdir); 415 } 416 417 /* Don't fall back to fake X11 data for untrusted forwarding */ 418 if (!trusted && !got_data) { 419 error("Warning: untrusted X11 forwarding setup failed: " 420 "xauth key data not generated"); 421 return -1; 422 } 423 424 /* 425 * If we didn't get authentication data, just make up some 426 * data. The forwarding code will check the validity of the 427 * response anyway, and substitute this data. The X11 428 * server, however, will ignore this fake data and use 429 * whatever authentication mechanisms it was using otherwise 430 * for the local connection. 431 */ 432 if (!got_data) { 433 u_int8_t rnd[16]; 434 u_int i; 435 436 logit("Warning: No xauth data; " 437 "using fake authentication data for X11 forwarding."); 438 strlcpy(proto, SSH_X11_PROTO, sizeof proto); 439 arc4random_buf(rnd, sizeof(rnd)); 440 for (i = 0; i < sizeof(rnd); i++) { 441 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", 442 rnd[i]); 443 } 444 } 445 446 return 0; 447 } 448 449 /* 450 * Checks if the client window has changed, and sends a packet about it to 451 * the server if so. The actual change is detected elsewhere (by a software 452 * interrupt on Unix); this just checks the flag and sends a message if 453 * appropriate. 454 */ 455 456 static void 457 client_check_window_change(struct ssh *ssh) 458 { 459 if (!received_window_change_signal) 460 return; 461 received_window_change_signal = 0; 462 debug2_f("changed"); 463 channel_send_window_changes(ssh); 464 } 465 466 static int 467 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh) 468 { 469 struct global_confirm *gc; 470 471 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL) 472 return 0; 473 if (gc->cb != NULL) 474 gc->cb(ssh, type, seq, gc->ctx); 475 if (--gc->ref_count <= 0) { 476 TAILQ_REMOVE(&global_confirms, gc, entry); 477 freezero(gc, sizeof(*gc)); 478 } 479 480 ssh_packet_set_alive_timeouts(ssh, 0); 481 return 0; 482 } 483 484 static void 485 schedule_server_alive_check(void) 486 { 487 if (options.server_alive_interval > 0) 488 server_alive_time = monotime() + options.server_alive_interval; 489 } 490 491 static void 492 server_alive_check(struct ssh *ssh) 493 { 494 int r; 495 496 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) { 497 logit("Timeout, server %s not responding.", host); 498 cleanup_exit(255); 499 } 500 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 501 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 || 502 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */ 503 (r = sshpkt_send(ssh)) != 0) 504 fatal_fr(r, "send packet"); 505 /* Insert an empty placeholder to maintain ordering */ 506 client_register_global_confirm(NULL, NULL); 507 schedule_server_alive_check(); 508 } 509 510 /* Try to send a dummy keystroke */ 511 static int 512 send_chaff(struct ssh *ssh) 513 { 514 int r; 515 516 if (ssh->kex == NULL || (ssh->kex->flags & KEX_HAS_PING) == 0) 517 return 0; 518 /* XXX probabilistically send chaff? */ 519 /* 520 * a SSH2_MSG_CHANNEL_DATA payload is 9 bytes: 521 * 4 bytes channel ID + 4 bytes string length + 1 byte string data 522 * simulate that here. 523 */ 524 if ((r = sshpkt_start(ssh, SSH2_MSG_PING)) != 0 || 525 (r = sshpkt_put_cstring(ssh, "PING!")) != 0 || 526 (r = sshpkt_send(ssh)) != 0) 527 fatal_fr(r, "send packet"); 528 return 1; 529 } 530 531 /* Sets the next interval to send a keystroke or chaff packet */ 532 static void 533 set_next_interval(const struct timespec *now, struct timespec *next_interval, 534 u_int interval_ms, int starting) 535 { 536 struct timespec tmp; 537 long long interval_ns, fuzz_ns; 538 static long long rate_fuzz; 539 540 interval_ns = interval_ms * (1000LL * 1000); 541 fuzz_ns = (interval_ns * SSH_KEYSTROKE_TIMING_FUZZ) / 100; 542 /* Center fuzz around requested interval */ 543 if (fuzz_ns > INT_MAX) 544 fuzz_ns = INT_MAX; 545 if (fuzz_ns > interval_ns) { 546 /* Shouldn't happen */ 547 fatal_f("internal error: fuzz %u%% %lldns > interval %lldns", 548 SSH_KEYSTROKE_TIMING_FUZZ, fuzz_ns, interval_ns); 549 } 550 /* 551 * Randomise the keystroke/chaff intervals in two ways: 552 * 1. Each interval has some random jitter applied to make the 553 * interval-to-interval time unpredictable. 554 * 2. The overall interval rate is also randomly perturbed for each 555 * chaffing session to make the average rate unpredictable. 556 */ 557 if (starting) 558 rate_fuzz = arc4random_uniform(fuzz_ns); 559 interval_ns -= fuzz_ns; 560 interval_ns += arc4random_uniform(fuzz_ns) + rate_fuzz; 561 562 tmp.tv_sec = interval_ns / (1000 * 1000 * 1000); 563 tmp.tv_nsec = interval_ns % (1000 * 1000 * 1000); 564 565 timespecadd(now, &tmp, next_interval); 566 } 567 568 /* 569 * Performs keystroke timing obfuscation. Returns non-zero if the 570 * output fd should be polled. 571 */ 572 static int 573 obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout, 574 int channel_did_enqueue) 575 { 576 static int active; 577 static struct timespec next_interval, chaff_until; 578 struct timespec now, tmp; 579 int just_started = 0, had_keystroke = 0; 580 static unsigned long long nchaff; 581 const char *stop_reason = NULL; 582 long long n; 583 584 monotime_ts(&now); 585 586 if (options.obscure_keystroke_timing_interval <= 0) 587 return 1; /* disabled in config */ 588 589 if (!channel_tty_open(ssh) || quit_pending) { 590 /* Stop if no channels left of we're waiting for one to close */ 591 stop_reason = "no active channels"; 592 } else if (ssh_packet_is_rekeying(ssh)) { 593 /* Stop if we're rekeying */ 594 stop_reason = "rekeying started"; 595 } else if (!ssh_packet_interactive_data_to_write(ssh) && 596 ssh_packet_have_data_to_write(ssh)) { 597 /* Stop if the output buffer has more than a few keystrokes */ 598 stop_reason = "output buffer filling"; 599 } else if (active && channel_did_enqueue && 600 ssh_packet_have_data_to_write(ssh)) { 601 /* Still in active mode and have a keystroke queued. */ 602 had_keystroke = 1; 603 } else if (active) { 604 if (timespeccmp(&now, &chaff_until, >=)) { 605 /* Stop if there have been no keystrokes for a while */ 606 stop_reason = "chaff time expired"; 607 } else if (timespeccmp(&now, &next_interval, >=)) { 608 /* Otherwise if we were due to send, then send chaff */ 609 if (send_chaff(ssh)) 610 nchaff++; 611 } 612 } 613 614 if (stop_reason != NULL) { 615 if (active) { 616 debug3_f("stopping: %s (%llu chaff packets sent)", 617 stop_reason, nchaff); 618 active = 0; 619 } 620 return 1; 621 } 622 623 /* 624 * If we're in interactive mode, and only have a small amount 625 * of outbound data, then we assume that the user is typing 626 * interactively. In this case, start quantising outbound packets to 627 * fixed time intervals to hide inter-keystroke timing. 628 */ 629 if (!active && ssh_packet_interactive_data_to_write(ssh) && 630 channel_did_enqueue && ssh_packet_have_data_to_write(ssh)) { 631 debug3_f("starting: interval ~%dms", 632 options.obscure_keystroke_timing_interval); 633 just_started = had_keystroke = active = 1; 634 nchaff = 0; 635 set_next_interval(&now, &next_interval, 636 options.obscure_keystroke_timing_interval, 1); 637 } 638 639 /* Don't hold off if obfuscation inactive */ 640 if (!active) 641 return 1; 642 643 if (had_keystroke) { 644 /* 645 * Arrange to send chaff packets for a random interval after 646 * the last keystroke was sent. 647 */ 648 ms_to_timespec(&tmp, SSH_KEYSTROKE_CHAFF_MIN_MS + 649 arc4random_uniform(SSH_KEYSTROKE_CHAFF_RNG_MS)); 650 timespecadd(&now, &tmp, &chaff_until); 651 } 652 653 ptimeout_deadline_monotime_tsp(timeout, &next_interval); 654 655 if (just_started) 656 return 1; 657 658 /* Don't arm output fd for poll until the timing interval has elapsed */ 659 if (timespeccmp(&now, &next_interval, <)) 660 return 0; 661 662 /* Calculate number of intervals missed since the last check */ 663 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000; 664 n += now.tv_nsec - next_interval.tv_nsec; 665 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000; 666 n = (n < 0) ? 1 : n + 1; 667 668 /* Advance to the next interval */ 669 set_next_interval(&now, &next_interval, 670 options.obscure_keystroke_timing_interval * n, 0); 671 return 1; 672 } 673 674 /* 675 * Waits until the client can do something (some data becomes available on 676 * one of the file descriptors). 677 */ 678 static void 679 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp, 680 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue, 681 sigset_t *sigsetp, int *conn_in_readyp, int *conn_out_readyp) 682 { 683 struct timespec timeout; 684 int ret, oready; 685 u_int p; 686 687 *conn_in_readyp = *conn_out_readyp = 0; 688 689 /* Prepare channel poll. First two pollfd entries are reserved */ 690 ptimeout_init(&timeout); 691 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 692 if (*npfd_activep < 2) 693 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 694 695 /* channel_prepare_poll could have closed the last channel */ 696 if (session_closed && !channel_still_open(ssh) && 697 !ssh_packet_have_data_to_write(ssh)) { 698 /* clear events since we did not call poll() */ 699 for (p = 0; p < *npfd_activep; p++) 700 (*pfdp)[p].revents = 0; 701 return; 702 } 703 704 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue); 705 706 /* Monitor server connection on reserved pollfd entries */ 707 (*pfdp)[0].fd = connection_in; 708 (*pfdp)[0].events = POLLIN; 709 (*pfdp)[1].fd = connection_out; 710 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ? 711 POLLOUT : 0; 712 713 /* 714 * Wait for something to happen. This will suspend the process until 715 * some polled descriptor can be read, written, or has some other 716 * event pending, or a timeout expires. 717 */ 718 set_control_persist_exit_time(ssh); 719 if (control_persist_exit_time > 0) 720 ptimeout_deadline_monotime(&timeout, control_persist_exit_time); 721 if (options.server_alive_interval > 0) 722 ptimeout_deadline_monotime(&timeout, server_alive_time); 723 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 724 ptimeout_deadline_sec(&timeout, 725 ssh_packet_get_rekey_timeout(ssh)); 726 } 727 728 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp); 729 730 if (ret == -1) { 731 /* 732 * We have to clear the events because we return. 733 * We have to return, because the mainloop checks for the flags 734 * set by the signal handlers. 735 */ 736 for (p = 0; p < *npfd_activep; p++) 737 (*pfdp)[p].revents = 0; 738 if (errno == EINTR) 739 return; 740 /* Note: we might still have data in the buffers. */ 741 quit_message("poll: %s", strerror(errno)); 742 return; 743 } 744 745 *conn_in_readyp = (*pfdp)[0].revents != 0; 746 *conn_out_readyp = (*pfdp)[1].revents != 0; 747 748 if (options.server_alive_interval > 0 && !*conn_in_readyp && 749 monotime() >= server_alive_time) { 750 /* 751 * ServerAlive check is needed. We can't rely on the poll 752 * timing out since traffic on the client side such as port 753 * forwards can keep waking it up. 754 */ 755 server_alive_check(ssh); 756 } 757 } 758 759 static void 760 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr) 761 { 762 /* Flush stdout and stderr buffers. */ 763 if (sshbuf_len(bout) > 0) 764 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout), 765 sshbuf_len(bout)); 766 if (sshbuf_len(berr) > 0) 767 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr), 768 sshbuf_len(berr)); 769 770 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 771 772 sshbuf_reset(bin); 773 sshbuf_reset(bout); 774 sshbuf_reset(berr); 775 776 /* Send the suspend signal to the program itself. */ 777 kill(getpid(), SIGTSTP); 778 779 /* Reset window sizes in case they have changed */ 780 received_window_change_signal = 1; 781 782 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 783 } 784 785 static void 786 client_process_net_input(struct ssh *ssh) 787 { 788 int r; 789 790 /* 791 * Read input from the server, and add any such data to the buffer of 792 * the packet subsystem. 793 */ 794 schedule_server_alive_check(); 795 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 796 return; /* success */ 797 if (r == SSH_ERR_SYSTEM_ERROR) { 798 if (errno == EAGAIN || errno == EINTR) 799 return; 800 if (errno == EPIPE) { 801 quit_message("Connection to %s closed by remote host.", 802 host); 803 return; 804 } 805 } 806 quit_message("Read from remote host %s: %s", host, ssh_err(r)); 807 } 808 809 static void 810 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) 811 { 812 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; 813 char errmsg[256]; 814 int r, tochan; 815 816 /* 817 * If a TTY was explicitly requested, then a failure to allocate 818 * one is fatal. 819 */ 820 if (cr->action == CONFIRM_TTY && 821 (options.request_tty == REQUEST_TTY_FORCE || 822 options.request_tty == REQUEST_TTY_YES)) 823 cr->action = CONFIRM_CLOSE; 824 825 /* XXX suppress on mux _client_ quietmode */ 826 tochan = options.log_level >= SYSLOG_LEVEL_ERROR && 827 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; 828 829 if (type == SSH2_MSG_CHANNEL_SUCCESS) { 830 debug2("%s request accepted on channel %d", 831 cr->request_type, c->self); 832 } else if (type == SSH2_MSG_CHANNEL_FAILURE) { 833 if (tochan) { 834 snprintf(errmsg, sizeof(errmsg), 835 "%s request failed\r\n", cr->request_type); 836 } else { 837 snprintf(errmsg, sizeof(errmsg), 838 "%s request failed on channel %d", 839 cr->request_type, c->self); 840 } 841 /* If error occurred on primary session channel, then exit */ 842 if (cr->action == CONFIRM_CLOSE && c->self == session_ident) 843 fatal("%s", errmsg); 844 /* 845 * If error occurred on mux client, append to 846 * their stderr. 847 */ 848 if (tochan) { 849 debug3_f("channel %d: mux request: %s", c->self, 850 cr->request_type); 851 if ((r = sshbuf_put(c->extended, errmsg, 852 strlen(errmsg))) != 0) 853 fatal_fr(r, "sshbuf_put"); 854 } else 855 error("%s", errmsg); 856 if (cr->action == CONFIRM_TTY) { 857 /* 858 * If a TTY allocation error occurred, then arrange 859 * for the correct TTY to leave raw mode. 860 */ 861 if (c->self == session_ident) 862 leave_raw_mode(0); 863 else 864 mux_tty_alloc_failed(ssh, c); 865 } else if (cr->action == CONFIRM_CLOSE) { 866 chan_read_failed(ssh, c); 867 chan_write_failed(ssh, c); 868 } 869 } 870 free(cr); 871 } 872 873 static void 874 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) 875 { 876 free(ctx); 877 } 878 879 void 880 client_expect_confirm(struct ssh *ssh, int id, const char *request, 881 enum confirm_action action) 882 { 883 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); 884 885 cr->request_type = request; 886 cr->action = action; 887 888 channel_register_status_confirm(ssh, id, client_status_confirm, 889 client_abandon_status_confirm, cr); 890 } 891 892 void 893 client_register_global_confirm(global_confirm_cb *cb, void *ctx) 894 { 895 struct global_confirm *gc, *last_gc; 896 897 /* Coalesce identical callbacks */ 898 last_gc = TAILQ_LAST(&global_confirms, global_confirms); 899 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { 900 if (++last_gc->ref_count >= INT_MAX) 901 fatal_f("last_gc->ref_count = %d", 902 last_gc->ref_count); 903 return; 904 } 905 906 gc = xcalloc(1, sizeof(*gc)); 907 gc->cb = cb; 908 gc->ctx = ctx; 909 gc->ref_count = 1; 910 TAILQ_INSERT_TAIL(&global_confirms, gc, entry); 911 } 912 913 /* 914 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com 915 * hostkey update request. 916 */ 917 static int 918 can_update_hostkeys(void) 919 { 920 if (hostkeys_update_complete) 921 return 0; 922 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && 923 options.batch_mode) 924 return 0; /* won't ask in batchmode, so don't even try */ 925 if (!options.update_hostkeys || options.num_user_hostfiles <= 0) 926 return 0; 927 return 1; 928 } 929 930 static void 931 client_repledge(void) 932 { 933 debug3_f("enter"); 934 935 /* Might be able to tighten pledge now that session is established */ 936 if (options.control_master || options.control_path != NULL || 937 options.forward_x11 || options.fork_after_authentication || 938 can_update_hostkeys() || 939 (session_ident != -1 && !session_setup_complete)) { 940 /* Can't tighten */ 941 return; 942 } 943 #ifdef __OpenBSD__ 944 /* 945 * LocalCommand and UpdateHostkeys have finished, so can get rid of 946 * filesystem. 947 * 948 * XXX protocol allows a server can to change hostkeys during the 949 * connection at rekey time that could trigger a hostkeys update 950 * but AFAIK no implementations support this. Could improve by 951 * forcing known_hosts to be read-only or via unveil(2). 952 */ 953 if (options.num_local_forwards != 0 || 954 options.num_remote_forwards != 0 || 955 options.num_permitted_remote_opens != 0 || 956 options.enable_escape_commandline != 0) { 957 /* rfwd needs inet */ 958 debug("pledge: network"); 959 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 960 fatal_f("pledge(): %s", strerror(errno)); 961 } else if (options.forward_agent != 0) { 962 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */ 963 debug("pledge: agent"); 964 if (pledge("stdio unix proc tty", NULL) == -1) 965 fatal_f("pledge(): %s", strerror(errno)); 966 } else { 967 debug("pledge: fork"); 968 if (pledge("stdio proc tty", NULL) == -1) 969 fatal_f("pledge(): %s", strerror(errno)); 970 } 971 #endif 972 /* XXX further things to do: 973 * 974 * - might be able to get rid of proc if we kill ~^Z 975 * - ssh -N (no session) 976 * - stdio forwarding 977 * - sessions without tty 978 */ 979 } 980 981 static void 982 process_cmdline(struct ssh *ssh) 983 { 984 void (*handler)(int); 985 char *s, *cmd; 986 int ok, delete = 0, local = 0, remote = 0, dynamic = 0; 987 struct Forward fwd; 988 989 memset(&fwd, 0, sizeof(fwd)); 990 991 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 992 handler = ssh_signal(SIGINT, SIG_IGN); 993 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); 994 if (s == NULL) 995 goto out; 996 while (isspace((u_char)*s)) 997 s++; 998 if (*s == '-') 999 s++; /* Skip cmdline '-', if any */ 1000 if (*s == '\0') 1001 goto out; 1002 1003 if (*s == 'h' || *s == 'H' || *s == '?') { 1004 logit("Commands:"); 1005 logit(" -L[bind_address:]port:host:hostport " 1006 "Request local forward"); 1007 logit(" -R[bind_address:]port:host:hostport " 1008 "Request remote forward"); 1009 logit(" -D[bind_address:]port " 1010 "Request dynamic forward"); 1011 logit(" -KL[bind_address:]port " 1012 "Cancel local forward"); 1013 logit(" -KR[bind_address:]port " 1014 "Cancel remote forward"); 1015 logit(" -KD[bind_address:]port " 1016 "Cancel dynamic forward"); 1017 if (!options.permit_local_command) 1018 goto out; 1019 logit(" !args " 1020 "Execute local command"); 1021 goto out; 1022 } 1023 1024 if (*s == '!' && options.permit_local_command) { 1025 s++; 1026 ssh_local_cmd(s); 1027 goto out; 1028 } 1029 1030 if (*s == 'K') { 1031 delete = 1; 1032 s++; 1033 } 1034 if (*s == 'L') 1035 local = 1; 1036 else if (*s == 'R') 1037 remote = 1; 1038 else if (*s == 'D') 1039 dynamic = 1; 1040 else { 1041 logit("Invalid command."); 1042 goto out; 1043 } 1044 1045 while (isspace((u_char)*++s)) 1046 ; 1047 1048 /* XXX update list of forwards in options */ 1049 if (delete) { 1050 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ 1051 if (!parse_forward(&fwd, s, 1, 0)) { 1052 logit("Bad forwarding close specification."); 1053 goto out; 1054 } 1055 if (remote) 1056 ok = channel_request_rforward_cancel(ssh, &fwd) == 0; 1057 else if (dynamic) 1058 ok = channel_cancel_lport_listener(ssh, &fwd, 1059 0, &options.fwd_opts) > 0; 1060 else 1061 ok = channel_cancel_lport_listener(ssh, &fwd, 1062 CHANNEL_CANCEL_PORT_STATIC, 1063 &options.fwd_opts) > 0; 1064 if (!ok) { 1065 logit("Unknown port forwarding."); 1066 goto out; 1067 } 1068 logit("Canceled forwarding."); 1069 } else { 1070 /* -R specs can be both dynamic or not, so check both. */ 1071 if (remote) { 1072 if (!parse_forward(&fwd, s, 0, remote) && 1073 !parse_forward(&fwd, s, 1, remote)) { 1074 logit("Bad remote forwarding specification."); 1075 goto out; 1076 } 1077 } else if (!parse_forward(&fwd, s, dynamic, remote)) { 1078 logit("Bad local forwarding specification."); 1079 goto out; 1080 } 1081 if (local || dynamic) { 1082 if (!channel_setup_local_fwd_listener(ssh, &fwd, 1083 &options.fwd_opts)) { 1084 logit("Port forwarding failed."); 1085 goto out; 1086 } 1087 } else { 1088 if (channel_request_remote_forwarding(ssh, &fwd) < 0) { 1089 logit("Port forwarding failed."); 1090 goto out; 1091 } 1092 } 1093 logit("Forwarding port."); 1094 } 1095 1096 out: 1097 ssh_signal(SIGINT, handler); 1098 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1099 free(cmd); 1100 free(fwd.listen_host); 1101 free(fwd.listen_path); 1102 free(fwd.connect_host); 1103 free(fwd.connect_path); 1104 } 1105 1106 /* reasons to suppress output of an escape command in help output */ 1107 #define SUPPRESS_NEVER 0 /* never suppress, always show */ 1108 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ 1109 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ 1110 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ 1111 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/ 1112 struct escape_help_text { 1113 const char *cmd; 1114 const char *text; 1115 unsigned int flags; 1116 }; 1117 static struct escape_help_text esc_txt[] = { 1118 {".", "terminate session", SUPPRESS_MUXMASTER}, 1119 {".", "terminate connection (and any multiplexed sessions)", 1120 SUPPRESS_MUXCLIENT}, 1121 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, 1122 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE}, 1123 {"R", "request rekey", SUPPRESS_NEVER}, 1124 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, 1125 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, 1126 {"#", "list forwarded connections", SUPPRESS_NEVER}, 1127 {"&", "background ssh (when waiting for connections to terminate)", 1128 SUPPRESS_MUXCLIENT}, 1129 {"?", "this message", SUPPRESS_NEVER}, 1130 }; 1131 1132 static void 1133 print_escape_help(struct sshbuf *b, int escape_char, int mux_client, 1134 int using_stderr) 1135 { 1136 unsigned int i, suppress_flags; 1137 int r; 1138 1139 if ((r = sshbuf_putf(b, 1140 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0) 1141 fatal_fr(r, "sshbuf_putf"); 1142 1143 suppress_flags = 1144 (mux_client ? SUPPRESS_MUXCLIENT : 0) | 1145 (mux_client ? 0 : SUPPRESS_MUXMASTER) | 1146 (using_stderr ? 0 : SUPPRESS_SYSLOG) | 1147 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0); 1148 1149 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { 1150 if (esc_txt[i].flags & suppress_flags) 1151 continue; 1152 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n", 1153 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0) 1154 fatal_fr(r, "sshbuf_putf"); 1155 } 1156 1157 if ((r = sshbuf_putf(b, 1158 " %c%c - send the escape character by typing it twice\r\n" 1159 "(Note that escapes are only recognized immediately after " 1160 "newline.)\r\n", escape_char, escape_char)) != 0) 1161 fatal_fr(r, "sshbuf_putf"); 1162 } 1163 1164 /* 1165 * Process the characters one by one. 1166 */ 1167 static int 1168 process_escapes(struct ssh *ssh, Channel *c, 1169 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr, 1170 const char *buf, int len) 1171 { 1172 pid_t pid; 1173 int r, bytes = 0; 1174 u_int i; 1175 u_char ch; 1176 char *s; 1177 struct escape_filter_ctx *efc; 1178 1179 if (c == NULL || c->filter_ctx == NULL || len <= 0) 1180 return 0; 1181 1182 efc = (struct escape_filter_ctx *)c->filter_ctx; 1183 1184 for (i = 0; i < (u_int)len; i++) { 1185 /* Get one character at a time. */ 1186 ch = buf[i]; 1187 1188 if (efc->escape_pending) { 1189 /* We have previously seen an escape character. */ 1190 /* Clear the flag now. */ 1191 efc->escape_pending = 0; 1192 1193 /* Process the escaped character. */ 1194 switch (ch) { 1195 case '.': 1196 /* Terminate the connection. */ 1197 if ((r = sshbuf_putf(berr, "%c.\r\n", 1198 efc->escape_char)) != 0) 1199 fatal_fr(r, "sshbuf_putf"); 1200 if (c && c->ctl_chan != -1) { 1201 channel_force_close(ssh, c, 1); 1202 return 0; 1203 } else 1204 quit_pending = 1; 1205 return -1; 1206 1207 case 'Z' - 64: 1208 /* XXX support this for mux clients */ 1209 if (c && c->ctl_chan != -1) { 1210 char b[16]; 1211 noescape: 1212 if (ch == 'Z' - 64) 1213 snprintf(b, sizeof b, "^Z"); 1214 else 1215 snprintf(b, sizeof b, "%c", ch); 1216 if ((r = sshbuf_putf(berr, 1217 "%c%s escape not available to " 1218 "multiplexed sessions\r\n", 1219 efc->escape_char, b)) != 0) 1220 fatal_fr(r, "sshbuf_putf"); 1221 continue; 1222 } 1223 /* Suspend the program. Inform the user */ 1224 if ((r = sshbuf_putf(berr, 1225 "%c^Z [suspend ssh]\r\n", 1226 efc->escape_char)) != 0) 1227 fatal_fr(r, "sshbuf_putf"); 1228 1229 /* Restore terminal modes and suspend. */ 1230 client_suspend_self(bin, bout, berr); 1231 1232 /* We have been continued. */ 1233 continue; 1234 1235 case 'B': 1236 if ((r = sshbuf_putf(berr, 1237 "%cB\r\n", efc->escape_char)) != 0) 1238 fatal_fr(r, "sshbuf_putf"); 1239 channel_request_start(ssh, c->self, "break", 0); 1240 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 || 1241 (r = sshpkt_send(ssh)) != 0) 1242 fatal_fr(r, "send packet"); 1243 continue; 1244 1245 case 'R': 1246 if (ssh->compat & SSH_BUG_NOREKEY) 1247 logit("Server does not " 1248 "support re-keying"); 1249 else 1250 need_rekeying = 1; 1251 continue; 1252 1253 case 'V': 1254 /* FALLTHROUGH */ 1255 case 'v': 1256 if (c && c->ctl_chan != -1) 1257 goto noescape; 1258 if (!log_is_on_stderr()) { 1259 if ((r = sshbuf_putf(berr, 1260 "%c%c [Logging to syslog]\r\n", 1261 efc->escape_char, ch)) != 0) 1262 fatal_fr(r, "sshbuf_putf"); 1263 continue; 1264 } 1265 if (ch == 'V' && options.log_level > 1266 SYSLOG_LEVEL_QUIET) 1267 log_change_level(--options.log_level); 1268 if (ch == 'v' && options.log_level < 1269 SYSLOG_LEVEL_DEBUG3) 1270 log_change_level(++options.log_level); 1271 if ((r = sshbuf_putf(berr, 1272 "%c%c [LogLevel %s]\r\n", 1273 efc->escape_char, ch, 1274 log_level_name(options.log_level))) != 0) 1275 fatal_fr(r, "sshbuf_putf"); 1276 continue; 1277 1278 case '&': 1279 if (c->ctl_chan != -1) 1280 goto noescape; 1281 /* 1282 * Detach the program (continue to serve 1283 * connections, but put in background and no 1284 * more new connections). 1285 */ 1286 /* Restore tty modes. */ 1287 leave_raw_mode( 1288 options.request_tty == REQUEST_TTY_FORCE); 1289 1290 /* Stop listening for new connections. */ 1291 channel_stop_listening(ssh); 1292 1293 if ((r = sshbuf_putf(berr, "%c& " 1294 "[backgrounded]\n", efc->escape_char)) != 0) 1295 fatal_fr(r, "sshbuf_putf"); 1296 1297 /* Fork into background. */ 1298 pid = fork(); 1299 if (pid == -1) { 1300 error("fork: %.100s", strerror(errno)); 1301 continue; 1302 } 1303 if (pid != 0) { /* This is the parent. */ 1304 /* The parent just exits. */ 1305 exit(0); 1306 } 1307 /* The child continues serving connections. */ 1308 /* fake EOF on stdin */ 1309 if ((r = sshbuf_put_u8(bin, 4)) != 0) 1310 fatal_fr(r, "sshbuf_put_u8"); 1311 return -1; 1312 case '?': 1313 print_escape_help(berr, efc->escape_char, 1314 (c && c->ctl_chan != -1), 1315 log_is_on_stderr()); 1316 continue; 1317 1318 case '#': 1319 if ((r = sshbuf_putf(berr, "%c#\r\n", 1320 efc->escape_char)) != 0) 1321 fatal_fr(r, "sshbuf_putf"); 1322 s = channel_open_message(ssh); 1323 if ((r = sshbuf_put(berr, s, strlen(s))) != 0) 1324 fatal_fr(r, "sshbuf_put"); 1325 free(s); 1326 continue; 1327 1328 case 'C': 1329 if (c && c->ctl_chan != -1) 1330 goto noescape; 1331 if (options.enable_escape_commandline == 0) { 1332 if ((r = sshbuf_putf(berr, 1333 "commandline disabled\r\n")) != 0) 1334 fatal_fr(r, "sshbuf_putf"); 1335 continue; 1336 } 1337 process_cmdline(ssh); 1338 continue; 1339 1340 default: 1341 if (ch != efc->escape_char) { 1342 if ((r = sshbuf_put_u8(bin, 1343 efc->escape_char)) != 0) 1344 fatal_fr(r, "sshbuf_put_u8"); 1345 bytes++; 1346 } 1347 /* Escaped characters fall through here */ 1348 break; 1349 } 1350 } else { 1351 /* 1352 * The previous character was not an escape char. 1353 * Check if this is an escape. 1354 */ 1355 if (last_was_cr && ch == efc->escape_char) { 1356 /* 1357 * It is. Set the flag and continue to 1358 * next character. 1359 */ 1360 efc->escape_pending = 1; 1361 continue; 1362 } 1363 } 1364 1365 /* 1366 * Normal character. Record whether it was a newline, 1367 * and append it to the buffer. 1368 */ 1369 last_was_cr = (ch == '\r' || ch == '\n'); 1370 if ((r = sshbuf_put_u8(bin, ch)) != 0) 1371 fatal_fr(r, "sshbuf_put_u8"); 1372 bytes++; 1373 } 1374 return bytes; 1375 } 1376 1377 /* 1378 * Get packets from the connection input buffer, and process them as long as 1379 * there are packets available. 1380 * 1381 * Any unknown packets received during the actual 1382 * session cause the session to terminate. This is 1383 * intended to make debugging easier since no 1384 * confirmations are sent. Any compatible protocol 1385 * extensions must be negotiated during the 1386 * preparatory phase. 1387 */ 1388 1389 static void 1390 client_process_buffered_input_packets(struct ssh *ssh) 1391 { 1392 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending); 1393 } 1394 1395 /* scan buf[] for '~' before sending data to the peer */ 1396 1397 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ 1398 void * 1399 client_new_escape_filter_ctx(int escape_char) 1400 { 1401 struct escape_filter_ctx *ret; 1402 1403 ret = xcalloc(1, sizeof(*ret)); 1404 ret->escape_pending = 0; 1405 ret->escape_char = escape_char; 1406 return (void *)ret; 1407 } 1408 1409 /* Free the escape filter context on channel free */ 1410 void 1411 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) 1412 { 1413 free(ctx); 1414 } 1415 1416 int 1417 client_simple_escape_filter(struct ssh *ssh, Channel *c, const char *buf, 1418 int len) 1419 { 1420 if (c->extended_usage != CHAN_EXTENDED_WRITE) 1421 return 0; 1422 1423 return process_escapes(ssh, c, c->input, c->output, c->extended, 1424 buf, len); 1425 } 1426 1427 static void 1428 client_channel_closed(struct ssh *ssh, int id, int force, void *arg) 1429 { 1430 channel_cancel_cleanup(ssh, id); 1431 session_closed = 1; 1432 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1433 } 1434 1435 /* 1436 * Implements the interactive session with the server. This is called after 1437 * the user has been authenticated, and a command has been started on the 1438 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character 1439 * used as an escape character for terminating or suspending the session. 1440 */ 1441 int 1442 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, 1443 int ssh2_chan_id) 1444 { 1445 struct pollfd *pfd = NULL; 1446 u_int npfd_alloc = 0, npfd_active = 0; 1447 double start_time, total_time; 1448 int channel_did_enqueue = 0, r, len; 1449 u_int64_t ibytes, obytes; 1450 int conn_in_ready, conn_out_ready; 1451 sigset_t bsigset, osigset; 1452 1453 debug("Entering interactive session."); 1454 session_ident = ssh2_chan_id; 1455 1456 #ifdef __OpenBSD__ 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 #endif 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 sshbuf_mutable_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 /* again is this really necessary for X11? */ 1818 if (options.hpn_disabled) 1819 c = channel_new(ssh, "x11-connection", 1820 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1821 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1822 else 1823 c = channel_new(ssh, "x11-connection", 1824 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1825 options.hpn_buffer_size, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1826 c->force_drain = 1; 1827 return c; 1828 } 1829 1830 static Channel * 1831 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1832 { 1833 Channel *c = NULL; 1834 int r, sock; 1835 1836 if (!options.forward_agent) { 1837 error("Warning: ssh server tried agent forwarding."); 1838 error("Warning: this is probably a break-in attempt by a " 1839 "malicious server."); 1840 return NULL; 1841 } 1842 if (forward_agent_sock_path == NULL) { 1843 r = ssh_get_authentication_socket(&sock); 1844 } else { 1845 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1846 } 1847 if (r != 0) { 1848 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1849 debug_fr(r, "ssh_get_authentication_socket"); 1850 return NULL; 1851 } 1852 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1853 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1854 debug_f("bound agent to hostkey"); 1855 else 1856 debug2_fr(r, "ssh_agent_bind_hostkey"); 1857 1858 if (options.hpn_disabled) 1859 c = channel_new(ssh, "agent-connection", 1860 SSH_CHANNEL_OPEN, sock, sock, -1, 1861 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1862 "authentication agent connection", 1); 1863 else 1864 c = channel_new(ssh, "agent connection", 1865 SSH_CHANNEL_OPEN, sock, sock, -1, 1866 options.hpn_buffer_size, options.hpn_buffer_size, 0, 1867 "authentication agent connection", 1); 1868 c->force_drain = 1; 1869 return c; 1870 } 1871 1872 char * 1873 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1874 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1875 { 1876 Channel *c; 1877 int r, fd; 1878 char *ifname = NULL; 1879 1880 if (tun_mode == SSH_TUNMODE_NO) 1881 return 0; 1882 1883 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1884 1885 /* Open local tunnel device */ 1886 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1887 error("Tunnel device open failed."); 1888 return NULL; 1889 } 1890 debug("Tunnel forwarding using interface %s", ifname); 1891 1892 if(options.hpn_disabled) 1893 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1894 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1895 else 1896 c = channel_new(ssh, "tun-connection", SSH_CHANNEL_OPENING, fd, fd, -1, 1897 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1898 c->datagram = 1; 1899 1900 if (cb != NULL) 1901 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1902 1903 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1904 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1905 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1906 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1907 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1908 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1909 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1910 (r = sshpkt_send(ssh)) != 0) 1911 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1912 1913 return ifname; 1914 } 1915 1916 /* XXXX move to generic input handler */ 1917 static int 1918 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1919 { 1920 Channel *c = NULL; 1921 char *ctype = NULL; 1922 int r; 1923 u_int rchan; 1924 size_t len; 1925 u_int rmaxpack, rwindow; 1926 1927 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1928 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1929 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1930 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1931 goto out; 1932 1933 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1934 ctype, rchan, rwindow, rmaxpack); 1935 1936 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1937 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1938 rmaxpack); 1939 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1940 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1941 } else if (strcmp(ctype, "x11") == 0) { 1942 c = client_request_x11(ssh, ctype, rchan); 1943 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1944 c = client_request_agent(ssh, ctype, rchan); 1945 } 1946 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1947 debug3("proxied to downstream: %s", ctype); 1948 } else if (c != NULL) { 1949 debug("confirm %s", ctype); 1950 c->remote_id = rchan; 1951 c->have_remote_id = 1; 1952 c->remote_window = rwindow; 1953 c->remote_maxpacket = rmaxpack; 1954 if (c->type != SSH_CHANNEL_CONNECTING) { 1955 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1956 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1957 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1958 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1959 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1960 (r = sshpkt_send(ssh)) != 0) 1961 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1962 } 1963 } else { 1964 debug("failure %s", ctype); 1965 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1966 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1967 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1968 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1969 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1970 (r = sshpkt_send(ssh)) != 0) 1971 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1972 } 1973 r = 0; 1974 out: 1975 free(ctype); 1976 return r; 1977 } 1978 1979 static int 1980 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1981 { 1982 Channel *c = NULL; 1983 char *rtype = NULL; 1984 u_char reply; 1985 u_int id, exitval; 1986 int r, success = 0; 1987 1988 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1989 return r; 1990 if (id <= INT_MAX) 1991 c = channel_lookup(ssh, id); 1992 if (channel_proxy_upstream(c, type, seq, ssh)) 1993 return 0; 1994 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1995 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1996 goto out; 1997 1998 debug("client_input_channel_req: channel %u rtype %s reply %d", 1999 id, rtype, reply); 2000 2001 if (c == NULL) { 2002 error("client_input_channel_req: channel %d: " 2003 "unknown channel", id); 2004 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 2005 if ((r = sshpkt_get_end(ssh)) != 0) 2006 goto out; 2007 chan_rcvd_eow(ssh, c); 2008 } else if (strcmp(rtype, "exit-status") == 0) { 2009 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 2010 goto out; 2011 if (c->ctl_chan != -1) { 2012 mux_exit_message(ssh, c, exitval); 2013 success = 1; 2014 } else if ((int)id == session_ident) { 2015 /* Record exit value of local session */ 2016 success = 1; 2017 exit_status = exitval; 2018 } else { 2019 /* Probably for a mux channel that has already closed */ 2020 debug_f("no sink for exit-status on channel %d", 2021 id); 2022 } 2023 if ((r = sshpkt_get_end(ssh)) != 0) 2024 goto out; 2025 } 2026 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 2027 if (!c->have_remote_id) 2028 fatal_f("channel %d: no remote_id", c->self); 2029 if ((r = sshpkt_start(ssh, success ? 2030 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2031 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2032 (r = sshpkt_send(ssh)) != 0) 2033 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2034 } 2035 r = 0; 2036 out: 2037 free(rtype); 2038 return r; 2039 } 2040 2041 struct hostkeys_update_ctx { 2042 /* The hostname and (optionally) IP address string for the server */ 2043 char *host_str, *ip_str; 2044 2045 /* 2046 * Keys received from the server and a flag for each indicating 2047 * whether they already exist in known_hosts. 2048 * keys_match is filled in by hostkeys_find() and later (for new 2049 * keys) by client_global_hostkeys_prove_confirm(). 2050 */ 2051 struct sshkey **keys; 2052 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2053 int *keys_verified; /* flag for new keys verified by server */ 2054 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2055 2056 /* 2057 * Keys that are in known_hosts, but were not present in the update 2058 * from the server (i.e. scheduled to be deleted). 2059 * Filled in by hostkeys_find(). 2060 */ 2061 struct sshkey **old_keys; 2062 size_t nold; 2063 2064 /* Various special cases. */ 2065 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2066 int ca_available; /* saw CA key for this host */ 2067 int old_key_seen; /* saw old key with other name/addr */ 2068 int other_name_seen; /* saw key with other name/addr */ 2069 }; 2070 2071 static void 2072 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2073 { 2074 size_t i; 2075 2076 if (ctx == NULL) 2077 return; 2078 for (i = 0; i < ctx->nkeys; i++) 2079 sshkey_free(ctx->keys[i]); 2080 free(ctx->keys); 2081 free(ctx->keys_match); 2082 free(ctx->keys_verified); 2083 for (i = 0; i < ctx->nold; i++) 2084 sshkey_free(ctx->old_keys[i]); 2085 free(ctx->old_keys); 2086 free(ctx->host_str); 2087 free(ctx->ip_str); 2088 free(ctx); 2089 } 2090 2091 /* 2092 * Returns non-zero if a known_hosts hostname list is not of a form that 2093 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2094 * hostnames lists that do not follow the form host[,ip]. 2095 */ 2096 static int 2097 hostspec_is_complex(const char *hosts) 2098 { 2099 char *cp; 2100 2101 /* wildcard */ 2102 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2103 return 1; 2104 /* single host/ip = ok */ 2105 if ((cp = strchr(hosts, ',')) == NULL) 2106 return 0; 2107 /* more than two entries on the line */ 2108 if (strchr(cp + 1, ',') != NULL) 2109 return 1; 2110 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2111 return 0; 2112 } 2113 2114 /* callback to search for ctx->keys in known_hosts */ 2115 static int 2116 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2117 { 2118 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2119 size_t i; 2120 struct sshkey **tmp; 2121 2122 if (l->key == NULL) 2123 return 0; 2124 if (l->status != HKF_STATUS_MATCHED) { 2125 /* Record if one of the keys appears on a non-matching line */ 2126 for (i = 0; i < ctx->nkeys; i++) { 2127 if (sshkey_equal(l->key, ctx->keys[i])) { 2128 ctx->other_name_seen = 1; 2129 debug3_f("found %s key under different " 2130 "name/addr at %s:%ld", 2131 sshkey_ssh_name(ctx->keys[i]), 2132 l->path, l->linenum); 2133 return 0; 2134 } 2135 } 2136 return 0; 2137 } 2138 /* Don't proceed if revocation or CA markers are present */ 2139 /* XXX relax this */ 2140 if (l->marker != MRK_NONE) { 2141 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2142 l->path, l->linenum); 2143 ctx->complex_hostspec = 1; 2144 return 0; 2145 } 2146 2147 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2148 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2149 if ((l->match & HKF_MATCH_HOST) == 0) { 2150 /* Record if address matched a different hostname. */ 2151 ctx->other_name_seen = 1; 2152 debug3_f("found address %s against different hostname " 2153 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2154 return 0; 2155 } else if ((l->match & HKF_MATCH_IP) == 0) { 2156 /* Record if hostname matched a different address. */ 2157 ctx->other_name_seen = 1; 2158 debug3_f("found hostname %s against different address " 2159 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2160 } 2161 } 2162 2163 /* 2164 * UpdateHostkeys is skipped for wildcard host names and hostnames 2165 * that contain more than two entries (ssh never writes these). 2166 */ 2167 if (hostspec_is_complex(l->hosts)) { 2168 debug3_f("hostkeys file %s:%ld complex host specification", 2169 l->path, l->linenum); 2170 ctx->complex_hostspec = 1; 2171 return 0; 2172 } 2173 2174 /* Mark off keys we've already seen for this host */ 2175 for (i = 0; i < ctx->nkeys; i++) { 2176 if (!sshkey_equal(l->key, ctx->keys[i])) 2177 continue; 2178 debug3_f("found %s key at %s:%ld", 2179 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2180 ctx->keys_match[i] |= l->match; 2181 return 0; 2182 } 2183 /* This line contained a key that not offered by the server */ 2184 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2185 l->path, l->linenum); 2186 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2187 sizeof(*ctx->old_keys))) == NULL) 2188 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2189 ctx->old_keys = tmp; 2190 ctx->old_keys[ctx->nold++] = l->key; 2191 l->key = NULL; 2192 2193 return 0; 2194 } 2195 2196 /* callback to search for ctx->old_keys in known_hosts under other names */ 2197 static int 2198 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2199 { 2200 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2201 size_t i; 2202 int hashed; 2203 2204 /* only care about lines that *don't* match the active host spec */ 2205 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2206 return 0; 2207 2208 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2209 for (i = 0; i < ctx->nold; i++) { 2210 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2211 continue; 2212 debug3_f("found deprecated %s key at %s:%ld as %s", 2213 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2214 hashed ? "[HASHED]" : l->hosts); 2215 ctx->old_key_seen = 1; 2216 break; 2217 } 2218 return 0; 2219 } 2220 2221 /* 2222 * Check known_hosts files for deprecated keys under other names. Returns 0 2223 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2224 * exist under names other than the active hostname/IP. 2225 */ 2226 static int 2227 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2228 { 2229 size_t i; 2230 int r; 2231 2232 debug2_f("checking for %zu deprecated keys", ctx->nold); 2233 for (i = 0; i < options.num_user_hostfiles; i++) { 2234 debug3_f("searching %s for %s / %s", 2235 options.user_hostfiles[i], ctx->host_str, 2236 ctx->ip_str ? ctx->ip_str : "(none)"); 2237 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2238 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2239 HKF_WANT_PARSE_KEY, 0)) != 0) { 2240 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2241 debug_f("hostkeys file %s does not exist", 2242 options.user_hostfiles[i]); 2243 continue; 2244 } 2245 error_fr(r, "hostkeys_foreach failed for %s", 2246 options.user_hostfiles[i]); 2247 return -1; 2248 } 2249 } 2250 return 0; 2251 } 2252 2253 static void 2254 hostkey_change_preamble(LogLevel loglevel) 2255 { 2256 do_log2(loglevel, "The server has updated its host keys."); 2257 do_log2(loglevel, "These changes were verified by the server's " 2258 "existing trusted key."); 2259 } 2260 2261 static void 2262 update_known_hosts(struct hostkeys_update_ctx *ctx) 2263 { 2264 int r, was_raw = 0, first = 1; 2265 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2266 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2267 char *fp, *response; 2268 size_t i; 2269 struct stat sb; 2270 2271 for (i = 0; i < ctx->nkeys; i++) { 2272 if (!ctx->keys_verified[i]) 2273 continue; 2274 if ((fp = sshkey_fingerprint(ctx->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, "Learned new hostkey: %s %s", 2280 sshkey_type(ctx->keys[i]), fp); 2281 first = 0; 2282 free(fp); 2283 } 2284 for (i = 0; i < ctx->nold; i++) { 2285 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2286 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2287 fatal_f("sshkey_fingerprint failed"); 2288 if (first && asking) 2289 hostkey_change_preamble(loglevel); 2290 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2291 sshkey_type(ctx->old_keys[i]), fp); 2292 first = 0; 2293 free(fp); 2294 } 2295 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2296 if (get_saved_tio() != NULL) { 2297 leave_raw_mode(1); 2298 was_raw = 1; 2299 } 2300 response = NULL; 2301 for (i = 0; !quit_pending && i < 3; i++) { 2302 free(response); 2303 response = read_passphrase("Accept updated hostkeys? " 2304 "(yes/no): ", RP_ECHO); 2305 if (response != NULL && strcasecmp(response, "yes") == 0) 2306 break; 2307 else if (quit_pending || response == NULL || 2308 strcasecmp(response, "no") == 0) { 2309 options.update_hostkeys = 0; 2310 break; 2311 } else { 2312 do_log2(loglevel, "Please enter " 2313 "\"yes\" or \"no\""); 2314 } 2315 } 2316 if (quit_pending || i >= 3 || response == NULL) 2317 options.update_hostkeys = 0; 2318 free(response); 2319 if (was_raw) 2320 enter_raw_mode(1); 2321 } 2322 if (options.update_hostkeys == 0) 2323 return; 2324 /* 2325 * Now that all the keys are verified, we can go ahead and replace 2326 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2327 * cancel the operation). 2328 */ 2329 for (i = 0; i < options.num_user_hostfiles; i++) { 2330 /* 2331 * NB. keys are only added to hostfiles[0], for the rest we 2332 * just delete the hostname entries. 2333 */ 2334 if (stat(options.user_hostfiles[i], &sb) != 0) { 2335 if (errno == ENOENT) { 2336 debug_f("known hosts file %s does not " 2337 "exist", options.user_hostfiles[i]); 2338 } else { 2339 error_f("known hosts file %s " 2340 "inaccessible: %s", 2341 options.user_hostfiles[i], strerror(errno)); 2342 } 2343 continue; 2344 } 2345 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2346 ctx->host_str, ctx->ip_str, 2347 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2348 options.hash_known_hosts, 0, 2349 options.fingerprint_hash)) != 0) { 2350 error_fr(r, "hostfile_replace_entries failed for %s", 2351 options.user_hostfiles[i]); 2352 } 2353 } 2354 } 2355 2356 static void 2357 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2358 u_int32_t seq, void *_ctx) 2359 { 2360 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2361 size_t i, ndone; 2362 struct sshbuf *signdata; 2363 int r, plaintype; 2364 const u_char *sig; 2365 const char *rsa_kexalg = NULL; 2366 char *alg = NULL; 2367 size_t siglen; 2368 2369 if (ctx->nnew == 0) 2370 fatal_f("ctx->nnew == 0"); /* sanity */ 2371 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2372 error("Server failed to confirm ownership of " 2373 "private host keys"); 2374 hostkeys_update_ctx_free(ctx); 2375 return; 2376 } 2377 if (sshkey_type_plain(sshkey_type_from_name( 2378 ssh->kex->hostkey_alg)) == KEY_RSA) 2379 rsa_kexalg = ssh->kex->hostkey_alg; 2380 if ((signdata = sshbuf_new()) == NULL) 2381 fatal_f("sshbuf_new failed"); 2382 /* 2383 * Expect a signature for each of the ctx->nnew private keys we 2384 * haven't seen before. They will be in the same order as the 2385 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2386 */ 2387 for (ndone = i = 0; i < ctx->nkeys; i++) { 2388 if (ctx->keys_match[i]) 2389 continue; 2390 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2391 /* Prepare data to be signed: session ID, unique string, key */ 2392 sshbuf_reset(signdata); 2393 if ( (r = sshbuf_put_cstring(signdata, 2394 "hostkeys-prove-00@openssh.com")) != 0 || 2395 (r = sshbuf_put_stringb(signdata, 2396 ssh->kex->session_id)) != 0 || 2397 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2398 fatal_fr(r, "compose signdata"); 2399 /* Extract and verify signature */ 2400 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2401 error_fr(r, "parse sig"); 2402 goto out; 2403 } 2404 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2405 error_fr(r, "server gave unintelligible signature " 2406 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2407 goto out; 2408 } 2409 /* 2410 * Special case for RSA keys: if a RSA hostkey was negotiated, 2411 * then use its signature type for verification of RSA hostkey 2412 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2413 */ 2414 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2415 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2416 debug_f("server used untrusted RSA signature algorithm " 2417 "%s for key %zu, disregarding", alg, i); 2418 free(alg); 2419 /* zap the key from the list */ 2420 sshkey_free(ctx->keys[i]); 2421 ctx->keys[i] = NULL; 2422 ndone++; 2423 continue; 2424 } 2425 debug3_f("verify %s key %zu using sigalg %s", 2426 sshkey_type(ctx->keys[i]), i, alg); 2427 free(alg); 2428 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2429 sshbuf_ptr(signdata), sshbuf_len(signdata), 2430 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2431 error_fr(r, "server gave bad signature for %s key %zu", 2432 sshkey_type(ctx->keys[i]), i); 2433 goto out; 2434 } 2435 /* Key is good. Mark it as 'seen' */ 2436 ctx->keys_verified[i] = 1; 2437 ndone++; 2438 } 2439 /* Shouldn't happen */ 2440 if (ndone != ctx->nnew) 2441 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2442 if ((r = sshpkt_get_end(ssh)) != 0) { 2443 error_f("protocol error"); 2444 goto out; 2445 } 2446 2447 /* Make the edits to known_hosts */ 2448 update_known_hosts(ctx); 2449 out: 2450 hostkeys_update_ctx_free(ctx); 2451 hostkeys_update_complete = 1; 2452 client_repledge(); 2453 } 2454 2455 /* 2456 * Returns non-zero if the key is accepted by HostkeyAlgorithms. 2457 * Made slightly less trivial by the multiple RSA signature algorithm names. 2458 */ 2459 static int 2460 key_accepted_by_hostkeyalgs(const struct sshkey *key) 2461 { 2462 const char *ktype = sshkey_ssh_name(key); 2463 const char *hostkeyalgs = options.hostkeyalgorithms; 2464 2465 if (key->type == KEY_UNSPEC) 2466 return 0; 2467 if (key->type == KEY_RSA && 2468 (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 || 2469 match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1)) 2470 return 1; 2471 return match_pattern_list(ktype, hostkeyalgs, 0) == 1; 2472 } 2473 2474 /* 2475 * Handle hostkeys-00@openssh.com global request to inform the client of all 2476 * the server's hostkeys. The keys are checked against the user's 2477 * HostkeyAlgorithms preference before they are accepted. 2478 */ 2479 static int 2480 client_input_hostkeys(struct ssh *ssh) 2481 { 2482 const u_char *blob = NULL; 2483 size_t i, len = 0; 2484 struct sshbuf *buf = NULL; 2485 struct sshkey *key = NULL, **tmp; 2486 int r, prove_sent = 0; 2487 char *fp; 2488 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2489 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2490 struct hostkeys_update_ctx *ctx = NULL; 2491 u_int want; 2492 2493 if (hostkeys_seen) 2494 fatal_f("server already sent hostkeys"); 2495 if (!can_update_hostkeys()) 2496 return 1; 2497 hostkeys_seen = 1; 2498 2499 ctx = xcalloc(1, sizeof(*ctx)); 2500 while (ssh_packet_remaining(ssh) > 0) { 2501 sshkey_free(key); 2502 key = NULL; 2503 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2504 error_fr(r, "parse key"); 2505 goto out; 2506 } 2507 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2508 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2509 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2510 "convert key"); 2511 continue; 2512 } 2513 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2514 SSH_FP_DEFAULT); 2515 debug3_f("received %s key %s", sshkey_type(key), fp); 2516 free(fp); 2517 2518 if (!key_accepted_by_hostkeyalgs(key)) { 2519 debug3_f("%s key not permitted by " 2520 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2521 continue; 2522 } 2523 /* Skip certs */ 2524 if (sshkey_is_cert(key)) { 2525 debug3_f("%s key is a certificate; skipping", 2526 sshkey_ssh_name(key)); 2527 continue; 2528 } 2529 /* Ensure keys are unique */ 2530 for (i = 0; i < ctx->nkeys; i++) { 2531 if (sshkey_equal(key, ctx->keys[i])) { 2532 error_f("received duplicated %s host key", 2533 sshkey_ssh_name(key)); 2534 goto out; 2535 } 2536 } 2537 /* Key is good, record it */ 2538 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2539 sizeof(*ctx->keys))) == NULL) 2540 fatal_f("recallocarray failed nkeys = %zu", 2541 ctx->nkeys); 2542 ctx->keys = tmp; 2543 ctx->keys[ctx->nkeys++] = key; 2544 key = NULL; 2545 } 2546 2547 if (ctx->nkeys == 0) { 2548 debug_f("server sent no hostkeys"); 2549 goto out; 2550 } 2551 2552 if ((ctx->keys_match = calloc(ctx->nkeys, 2553 sizeof(*ctx->keys_match))) == NULL || 2554 (ctx->keys_verified = calloc(ctx->nkeys, 2555 sizeof(*ctx->keys_verified))) == NULL) 2556 fatal_f("calloc failed"); 2557 2558 get_hostfile_hostname_ipaddr(host, 2559 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2560 options.port, &ctx->host_str, 2561 options.check_host_ip ? &ctx->ip_str : NULL); 2562 2563 /* Find which keys we already know about. */ 2564 for (i = 0; i < options.num_user_hostfiles; i++) { 2565 debug_f("searching %s for %s / %s", 2566 options.user_hostfiles[i], ctx->host_str, 2567 ctx->ip_str ? ctx->ip_str : "(none)"); 2568 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2569 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2570 HKF_WANT_PARSE_KEY, 0)) != 0) { 2571 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2572 debug_f("hostkeys file %s does not exist", 2573 options.user_hostfiles[i]); 2574 continue; 2575 } 2576 error_fr(r, "hostkeys_foreach failed for %s", 2577 options.user_hostfiles[i]); 2578 goto out; 2579 } 2580 } 2581 2582 /* Figure out if we have any new keys to add */ 2583 ctx->nnew = ctx->nincomplete = 0; 2584 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2585 for (i = 0; i < ctx->nkeys; i++) { 2586 if (ctx->keys_match[i] == 0) 2587 ctx->nnew++; 2588 if ((ctx->keys_match[i] & want) != want) 2589 ctx->nincomplete++; 2590 } 2591 2592 debug3_f("%zu server keys: %zu new, %zu retained, " 2593 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2594 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2595 ctx->nincomplete, ctx->nold); 2596 2597 if (ctx->nnew == 0 && ctx->nold == 0) { 2598 debug_f("no new or deprecated keys from server"); 2599 goto out; 2600 } 2601 2602 /* Various reasons why we cannot proceed with the update */ 2603 if (ctx->complex_hostspec) { 2604 debug_f("CA/revocation marker, manual host list or wildcard " 2605 "host pattern found, skipping UserKnownHostsFile update"); 2606 goto out; 2607 } 2608 if (ctx->other_name_seen) { 2609 debug_f("host key found matching a different name/address, " 2610 "skipping UserKnownHostsFile update"); 2611 goto out; 2612 } 2613 /* 2614 * If removing keys, check whether they appear under different 2615 * names/addresses and refuse to proceed if they do. This avoids 2616 * cases such as hosts with multiple names becoming inconsistent 2617 * with regards to CheckHostIP entries. 2618 * XXX UpdateHostkeys=force to override this (and other) checks? 2619 */ 2620 if (ctx->nold != 0) { 2621 if (check_old_keys_othernames(ctx) != 0) 2622 goto out; /* error already logged */ 2623 if (ctx->old_key_seen) { 2624 debug_f("key(s) for %s%s%s exist under other names; " 2625 "skipping UserKnownHostsFile update", 2626 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2627 ctx->ip_str == NULL ? "" : ctx->ip_str); 2628 goto out; 2629 } 2630 } 2631 2632 if (ctx->nnew == 0) { 2633 /* 2634 * We have some keys to remove or fix matching for. 2635 * We can proceed to do this without requiring a fresh proof 2636 * from the server. 2637 */ 2638 update_known_hosts(ctx); 2639 goto out; 2640 } 2641 /* 2642 * We have received previously-unseen keys from the server. 2643 * Ask the server to confirm ownership of the private halves. 2644 */ 2645 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2646 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2647 (r = sshpkt_put_cstring(ssh, 2648 "hostkeys-prove-00@openssh.com")) != 0 || 2649 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2650 fatal_fr(r, "prepare hostkeys-prove"); 2651 if ((buf = sshbuf_new()) == NULL) 2652 fatal_f("sshbuf_new"); 2653 for (i = 0; i < ctx->nkeys; i++) { 2654 if (ctx->keys_match[i]) 2655 continue; 2656 sshbuf_reset(buf); 2657 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2658 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2659 fatal_fr(r, "assemble hostkeys-prove"); 2660 } 2661 if ((r = sshpkt_send(ssh)) != 0) 2662 fatal_fr(r, "send hostkeys-prove"); 2663 client_register_global_confirm( 2664 client_global_hostkeys_prove_confirm, ctx); 2665 ctx = NULL; /* will be freed in callback */ 2666 prove_sent = 1; 2667 2668 /* Success */ 2669 out: 2670 hostkeys_update_ctx_free(ctx); 2671 sshkey_free(key); 2672 sshbuf_free(buf); 2673 if (!prove_sent) { 2674 /* UpdateHostkeys handling completed */ 2675 hostkeys_update_complete = 1; 2676 client_repledge(); 2677 } 2678 /* 2679 * NB. Return success for all cases. The server doesn't need to know 2680 * what the client does with its hosts file. 2681 */ 2682 return 1; 2683 } 2684 2685 static int 2686 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2687 { 2688 char *rtype; 2689 u_char want_reply; 2690 int r, success = 0; 2691 2692 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2693 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2694 goto out; 2695 debug("client_input_global_request: rtype %s want_reply %d", 2696 rtype, want_reply); 2697 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2698 success = client_input_hostkeys(ssh); 2699 if (want_reply) { 2700 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2701 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2702 (r = sshpkt_send(ssh)) != 0 || 2703 (r = ssh_packet_write_wait(ssh)) != 0) 2704 goto out; 2705 } 2706 r = 0; 2707 out: 2708 free(rtype); 2709 return r; 2710 } 2711 2712 static void 2713 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2714 { 2715 int r; 2716 2717 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2718 channel_request_start(ssh, id, "env", 0); 2719 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2720 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2721 (r = sshpkt_send(ssh)) != 0) 2722 fatal_fr(r, "send setenv"); 2723 } 2724 2725 void 2726 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2727 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2728 char **env) 2729 { 2730 size_t i, j, len; 2731 int matched, r; 2732 char *name, *val; 2733 Channel *c = NULL; 2734 2735 debug2_f("id %d", id); 2736 2737 if ((c = channel_lookup(ssh, id)) == NULL) 2738 fatal_f("channel %d: unknown channel", id); 2739 2740 ssh_packet_set_interactive(ssh, want_tty, 2741 options.ip_qos_interactive, options.ip_qos_bulk); 2742 2743 if (want_tty) { 2744 struct winsize ws; 2745 2746 /* Store window size in the packet. */ 2747 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2748 memset(&ws, 0, sizeof(ws)); 2749 2750 channel_request_start(ssh, id, "pty-req", 1); 2751 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2752 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2753 != 0 || 2754 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2755 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2756 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2757 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2758 fatal_fr(r, "build pty-req"); 2759 if (tiop == NULL) 2760 tiop = get_saved_tio(); 2761 ssh_tty_make_modes(ssh, -1, tiop); 2762 if ((r = sshpkt_send(ssh)) != 0) 2763 fatal_fr(r, "send pty-req"); 2764 /* XXX wait for reply */ 2765 c->client_tty = 1; 2766 } 2767 2768 /* Transfer any environment variables from client to server */ 2769 if (options.num_send_env != 0 && env != NULL) { 2770 debug("Sending environment."); 2771 for (i = 0; env[i] != NULL; i++) { 2772 /* Split */ 2773 name = xstrdup(env[i]); 2774 if ((val = strchr(name, '=')) == NULL) { 2775 free(name); 2776 continue; 2777 } 2778 *val++ = '\0'; 2779 2780 matched = 0; 2781 for (j = 0; j < options.num_send_env; j++) { 2782 if (match_pattern(name, options.send_env[j])) { 2783 matched = 1; 2784 break; 2785 } 2786 } 2787 if (!matched) { 2788 debug3("Ignored env %s", name); 2789 free(name); 2790 continue; 2791 } 2792 client_send_env(ssh, id, name, val); 2793 free(name); 2794 } 2795 } 2796 for (i = 0; i < options.num_setenv; i++) { 2797 /* Split */ 2798 name = xstrdup(options.setenv[i]); 2799 if ((val = strchr(name, '=')) == NULL) { 2800 free(name); 2801 continue; 2802 } 2803 *val++ = '\0'; 2804 client_send_env(ssh, id, name, val); 2805 free(name); 2806 } 2807 2808 len = sshbuf_len(cmd); 2809 if (len > 0) { 2810 if (len > 900) 2811 len = 900; 2812 if (want_subsystem) { 2813 debug("Sending subsystem: %.*s", 2814 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2815 channel_request_start(ssh, id, "subsystem", 1); 2816 client_expect_confirm(ssh, id, "subsystem", 2817 CONFIRM_CLOSE); 2818 } else { 2819 debug("Sending command: %.*s", 2820 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2821 channel_request_start(ssh, id, "exec", 1); 2822 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2823 } 2824 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2825 (r = sshpkt_send(ssh)) != 0) 2826 fatal_fr(r, "send command"); 2827 } else { 2828 channel_request_start(ssh, id, "shell", 1); 2829 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2830 if ((r = sshpkt_send(ssh)) != 0) 2831 fatal_fr(r, "send shell"); 2832 } 2833 2834 session_setup_complete = 1; 2835 client_repledge(); 2836 } 2837 2838 static void 2839 client_init_dispatch(struct ssh *ssh) 2840 { 2841 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2842 2843 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2844 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2845 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2846 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2847 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2848 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2849 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2850 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2851 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2852 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2853 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2854 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2855 2856 /* rekeying */ 2857 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2858 2859 /* global request reply messages */ 2860 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2861 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2862 } 2863 2864 void 2865 client_stop_mux(void) 2866 { 2867 if (options.control_path != NULL && muxserver_sock != -1) 2868 unlink(options.control_path); 2869 /* 2870 * If we are in persist mode, or don't have a shell, signal that we 2871 * should close when all active channels are closed. 2872 */ 2873 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2874 session_closed = 1; 2875 setproctitle("[stopped mux]"); 2876 } 2877 } 2878 2879 /* client specific fatal cleanup */ 2880 void 2881 cleanup_exit(int i) 2882 { 2883 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2884 if (options.control_path != NULL && muxserver_sock != -1) 2885 unlink(options.control_path); 2886 ssh_kill_proxy_command(); 2887 _exit(i); 2888 } 2889