1 /* $OpenBSD: clientloop.c,v 1.398 2023/09/10 03:51:55 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The main loop for the interactive session (client side). 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * 15 * Copyright (c) 1999 Theo de Raadt. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 * 37 * 38 * SSH2 support added by Markus Friedl. 39 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 50 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 51 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 52 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 53 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 54 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 55 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 56 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 57 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 58 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 59 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 60 */ 61 62 #include "includes.h" 63 64 #include <sys/types.h> 65 #include <sys/ioctl.h> 66 #ifdef HAVE_SYS_STAT_H 67 # include <sys/stat.h> 68 #endif 69 #ifdef HAVE_SYS_TIME_H 70 # include <sys/time.h> 71 #endif 72 #include <sys/socket.h> 73 74 #include <ctype.h> 75 #include <errno.h> 76 #ifdef HAVE_PATHS_H 77 #include <paths.h> 78 #endif 79 #ifdef HAVE_POLL_H 80 #include <poll.h> 81 #endif 82 #include <signal.h> 83 #include <stdio.h> 84 #include <stdlib.h> 85 #include <string.h> 86 #include <stdarg.h> 87 #include <termios.h> 88 #include <pwd.h> 89 #include <unistd.h> 90 #include <limits.h> 91 92 #include "openbsd-compat/sys-queue.h" 93 #include "xmalloc.h" 94 #include "ssh.h" 95 #include "ssh2.h" 96 #include "packet.h" 97 #include "sshbuf.h" 98 #include "compat.h" 99 #include "channels.h" 100 #include "dispatch.h" 101 #include "sshkey.h" 102 #include "cipher.h" 103 #include "kex.h" 104 #include "myproposal.h" 105 #include "log.h" 106 #include "misc.h" 107 #include "readconf.h" 108 #include "clientloop.h" 109 #include "sshconnect.h" 110 #include "authfd.h" 111 #include "atomicio.h" 112 #include "sshpty.h" 113 #include "match.h" 114 #include "msg.h" 115 #include "ssherr.h" 116 #include "hostfile.h" 117 118 /* Permitted RSA signature algorithms for UpdateHostkeys proofs */ 119 #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256" 120 121 /* Uncertainty (in percent) of keystroke timing intervals */ 122 #define SSH_KEYSTROKE_TIMING_FUZZ 10 123 124 /* import options */ 125 extern Options options; 126 127 /* Control socket */ 128 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */ 129 130 /* 131 * Name of the host we are connecting to. This is the name given on the 132 * command line, or the Hostname specified for the user-supplied name in a 133 * configuration file. 134 */ 135 extern char *host; 136 137 /* 138 * If this field is not NULL, the ForwardAgent socket is this path and different 139 * instead of SSH_AUTH_SOCK. 140 */ 141 extern char *forward_agent_sock_path; 142 143 /* 144 * Flag to indicate that we have received a window change signal which has 145 * not yet been processed. This will cause a message indicating the new 146 * window size to be sent to the server a little later. This is volatile 147 * because this is updated in a signal handler. 148 */ 149 static volatile sig_atomic_t received_window_change_signal = 0; 150 static volatile sig_atomic_t received_signal = 0; 151 152 /* Time when backgrounded control master using ControlPersist should exit */ 153 static time_t control_persist_exit_time = 0; 154 155 /* Common data for the client loop code. */ 156 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ 157 static int last_was_cr; /* Last character was a newline. */ 158 static int exit_status; /* Used to store the command exit status. */ 159 static struct sshbuf *stderr_buffer; /* Used for final exit message. */ 160 static int connection_in; /* Connection to server (input). */ 161 static int connection_out; /* Connection to server (output). */ 162 static int need_rekeying; /* Set to non-zero if rekeying is requested. */ 163 static int session_closed; /* In SSH2: login session closed. */ 164 static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */ 165 static time_t server_alive_time; /* Time to do server_alive_check */ 166 static int hostkeys_update_complete; 167 static int session_setup_complete; 168 169 static void client_init_dispatch(struct ssh *ssh); 170 int session_ident = -1; 171 172 /* Track escape per proto2 channel */ 173 struct escape_filter_ctx { 174 int escape_pending; 175 int escape_char; 176 }; 177 178 /* Context for channel confirmation replies */ 179 struct channel_reply_ctx { 180 const char *request_type; 181 int id; 182 enum confirm_action action; 183 }; 184 185 /* Global request success/failure callbacks */ 186 /* XXX move to struct ssh? */ 187 struct global_confirm { 188 TAILQ_ENTRY(global_confirm) entry; 189 global_confirm_cb *cb; 190 void *ctx; 191 int ref_count; 192 }; 193 TAILQ_HEAD(global_confirms, global_confirm); 194 static struct global_confirms global_confirms = 195 TAILQ_HEAD_INITIALIZER(global_confirms); 196 197 void ssh_process_session2_setup(int, int, int, struct sshbuf *); 198 static void quit_message(const char *fmt, ...) 199 __attribute__((__format__ (printf, 1, 2))); 200 201 static void 202 quit_message(const char *fmt, ...) 203 { 204 char *msg; 205 va_list args; 206 int r; 207 208 va_start(args, fmt); 209 xvasprintf(&msg, fmt, args); 210 va_end(args); 211 212 if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0) 213 fatal_fr(r, "sshbuf_putf"); 214 quit_pending = 1; 215 } 216 217 /* 218 * Signal handler for the window change signal (SIGWINCH). This just sets a 219 * flag indicating that the window has changed. 220 */ 221 static void 222 window_change_handler(int sig) 223 { 224 received_window_change_signal = 1; 225 } 226 227 /* 228 * Signal handler for signals that cause the program to terminate. These 229 * signals must be trapped to restore terminal modes. 230 */ 231 static void 232 signal_handler(int sig) 233 { 234 received_signal = sig; 235 quit_pending = 1; 236 } 237 238 /* 239 * Sets control_persist_exit_time to the absolute time when the 240 * backgrounded control master should exit due to expiry of the 241 * ControlPersist timeout. Sets it to 0 if we are not a backgrounded 242 * control master process, or if there is no ControlPersist timeout. 243 */ 244 static void 245 set_control_persist_exit_time(struct ssh *ssh) 246 { 247 if (muxserver_sock == -1 || !options.control_persist 248 || options.control_persist_timeout == 0) { 249 /* not using a ControlPersist timeout */ 250 control_persist_exit_time = 0; 251 } else if (channel_still_open(ssh)) { 252 /* some client connections are still open */ 253 if (control_persist_exit_time > 0) 254 debug2_f("cancel scheduled exit"); 255 control_persist_exit_time = 0; 256 } else if (control_persist_exit_time <= 0) { 257 /* a client connection has recently closed */ 258 control_persist_exit_time = monotime() + 259 (time_t)options.control_persist_timeout; 260 debug2_f("schedule exit in %d seconds", 261 options.control_persist_timeout); 262 } 263 /* else we are already counting down to the timeout */ 264 } 265 266 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_" 267 static int 268 client_x11_display_valid(const char *display) 269 { 270 size_t i, dlen; 271 272 if (display == NULL) 273 return 0; 274 275 dlen = strlen(display); 276 for (i = 0; i < dlen; i++) { 277 if (!isalnum((u_char)display[i]) && 278 strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) { 279 debug("Invalid character '%c' in DISPLAY", display[i]); 280 return 0; 281 } 282 } 283 return 1; 284 } 285 286 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1" 287 #define X11_TIMEOUT_SLACK 60 288 int 289 client_x11_get_proto(struct ssh *ssh, const char *display, 290 const char *xauth_path, u_int trusted, u_int timeout, 291 char **_proto, char **_data) 292 { 293 char *cmd, line[512], xdisplay[512]; 294 char xauthfile[PATH_MAX], xauthdir[PATH_MAX]; 295 static char proto[512], data[512]; 296 FILE *f; 297 int got_data = 0, generated = 0, do_unlink = 0, r; 298 struct stat st; 299 u_int now, x11_timeout_real; 300 301 *_proto = proto; 302 *_data = data; 303 proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0'; 304 305 if (!client_x11_display_valid(display)) { 306 if (display != NULL) 307 logit("DISPLAY \"%s\" invalid; disabling X11 forwarding", 308 display); 309 return -1; 310 } 311 if (xauth_path != NULL && stat(xauth_path, &st) == -1) { 312 debug("No xauth program."); 313 xauth_path = NULL; 314 } 315 316 if (xauth_path != NULL) { 317 /* 318 * Handle FamilyLocal case where $DISPLAY does 319 * not match an authorization entry. For this we 320 * just try "xauth list unix:displaynum.screennum". 321 * XXX: "localhost" match to determine FamilyLocal 322 * is not perfect. 323 */ 324 if (strncmp(display, "localhost:", 10) == 0) { 325 if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s", 326 display + 10)) < 0 || 327 (size_t)r >= sizeof(xdisplay)) { 328 error_f("display name too long"); 329 return -1; 330 } 331 display = xdisplay; 332 } 333 if (trusted == 0) { 334 /* 335 * Generate an untrusted X11 auth cookie. 336 * 337 * The authentication cookie should briefly outlive 338 * ssh's willingness to forward X11 connections to 339 * avoid nasty fail-open behaviour in the X server. 340 */ 341 mktemp_proto(xauthdir, sizeof(xauthdir)); 342 if (mkdtemp(xauthdir) == NULL) { 343 error_f("mkdtemp: %s", strerror(errno)); 344 return -1; 345 } 346 do_unlink = 1; 347 if ((r = snprintf(xauthfile, sizeof(xauthfile), 348 "%s/xauthfile", xauthdir)) < 0 || 349 (size_t)r >= sizeof(xauthfile)) { 350 error_f("xauthfile path too long"); 351 rmdir(xauthdir); 352 return -1; 353 } 354 355 if (timeout == 0) { 356 /* auth doesn't time out */ 357 xasprintf(&cmd, "%s -f %s generate %s %s " 358 "untrusted 2>%s", 359 xauth_path, xauthfile, display, 360 SSH_X11_PROTO, _PATH_DEVNULL); 361 } else { 362 /* Add some slack to requested expiry */ 363 if (timeout < UINT_MAX - X11_TIMEOUT_SLACK) 364 x11_timeout_real = timeout + 365 X11_TIMEOUT_SLACK; 366 else { 367 /* Don't overflow on long timeouts */ 368 x11_timeout_real = UINT_MAX; 369 } 370 xasprintf(&cmd, "%s -f %s generate %s %s " 371 "untrusted timeout %u 2>%s", 372 xauth_path, xauthfile, display, 373 SSH_X11_PROTO, x11_timeout_real, 374 _PATH_DEVNULL); 375 } 376 debug2_f("xauth command: %s", cmd); 377 378 if (timeout != 0 && x11_refuse_time == 0) { 379 now = monotime() + 1; 380 if (SSH_TIME_T_MAX - timeout < now) 381 x11_refuse_time = SSH_TIME_T_MAX; 382 else 383 x11_refuse_time = now + timeout; 384 channel_set_x11_refuse_time(ssh, 385 x11_refuse_time); 386 } 387 if (system(cmd) == 0) 388 generated = 1; 389 free(cmd); 390 } 391 392 /* 393 * When in untrusted mode, we read the cookie only if it was 394 * successfully generated as an untrusted one in the step 395 * above. 396 */ 397 if (trusted || generated) { 398 xasprintf(&cmd, 399 "%s %s%s list %s 2>" _PATH_DEVNULL, 400 xauth_path, 401 generated ? "-f " : "" , 402 generated ? xauthfile : "", 403 display); 404 debug2("x11_get_proto: %s", cmd); 405 f = popen(cmd, "r"); 406 if (f && fgets(line, sizeof(line), f) && 407 sscanf(line, "%*s %511s %511s", proto, data) == 2) 408 got_data = 1; 409 if (f) 410 pclose(f); 411 free(cmd); 412 } 413 } 414 415 if (do_unlink) { 416 unlink(xauthfile); 417 rmdir(xauthdir); 418 } 419 420 /* Don't fall back to fake X11 data for untrusted forwarding */ 421 if (!trusted && !got_data) { 422 error("Warning: untrusted X11 forwarding setup failed: " 423 "xauth key data not generated"); 424 return -1; 425 } 426 427 /* 428 * If we didn't get authentication data, just make up some 429 * data. The forwarding code will check the validity of the 430 * response anyway, and substitute this data. The X11 431 * server, however, will ignore this fake data and use 432 * whatever authentication mechanisms it was using otherwise 433 * for the local connection. 434 */ 435 if (!got_data) { 436 u_int8_t rnd[16]; 437 u_int i; 438 439 logit("Warning: No xauth data; " 440 "using fake authentication data for X11 forwarding."); 441 strlcpy(proto, SSH_X11_PROTO, sizeof proto); 442 arc4random_buf(rnd, sizeof(rnd)); 443 for (i = 0; i < sizeof(rnd); i++) { 444 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", 445 rnd[i]); 446 } 447 } 448 449 return 0; 450 } 451 452 /* 453 * Checks if the client window has changed, and sends a packet about it to 454 * the server if so. The actual change is detected elsewhere (by a software 455 * interrupt on Unix); this just checks the flag and sends a message if 456 * appropriate. 457 */ 458 459 static void 460 client_check_window_change(struct ssh *ssh) 461 { 462 if (!received_window_change_signal) 463 return; 464 received_window_change_signal = 0; 465 debug2_f("changed"); 466 channel_send_window_changes(ssh); 467 } 468 469 static int 470 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh) 471 { 472 struct global_confirm *gc; 473 474 if ((gc = TAILQ_FIRST(&global_confirms)) == NULL) 475 return 0; 476 if (gc->cb != NULL) 477 gc->cb(ssh, type, seq, gc->ctx); 478 if (--gc->ref_count <= 0) { 479 TAILQ_REMOVE(&global_confirms, gc, entry); 480 freezero(gc, sizeof(*gc)); 481 } 482 483 ssh_packet_set_alive_timeouts(ssh, 0); 484 return 0; 485 } 486 487 static void 488 schedule_server_alive_check(void) 489 { 490 if (options.server_alive_interval > 0) 491 server_alive_time = monotime() + options.server_alive_interval; 492 } 493 494 static void 495 server_alive_check(struct ssh *ssh) 496 { 497 int r; 498 499 if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) { 500 logit("Timeout, server %s not responding.", host); 501 cleanup_exit(255); 502 } 503 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 504 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 || 505 (r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */ 506 (r = sshpkt_send(ssh)) != 0) 507 fatal_fr(r, "send packet"); 508 /* Insert an empty placeholder to maintain ordering */ 509 client_register_global_confirm(NULL, NULL); 510 schedule_server_alive_check(); 511 } 512 513 /* Try to send a dummy keystroke */ 514 static int 515 send_chaff(struct ssh *ssh) 516 { 517 int r; 518 519 if ((ssh->kex->flags & KEX_HAS_PING) == 0) 520 return 0; 521 /* XXX probabilistically send chaff? */ 522 /* 523 * a SSH2_MSG_CHANNEL_DATA payload is 9 bytes: 524 * 4 bytes channel ID + 4 bytes string length + 1 byte string data 525 * simulate that here. 526 */ 527 if ((r = sshpkt_start(ssh, SSH2_MSG_PING)) != 0 || 528 (r = sshpkt_put_cstring(ssh, "PING!")) != 0 || 529 (r = sshpkt_send(ssh)) != 0) 530 fatal_fr(r, "send packet"); 531 return 1; 532 } 533 534 /* Sets the next interval to send a keystroke or chaff packet */ 535 static void 536 set_next_interval(const struct timespec *now, struct timespec *next_interval, 537 u_int interval_ms, int starting) 538 { 539 struct timespec tmp; 540 long long interval_ns, fuzz_ns; 541 static long long rate_fuzz; 542 543 interval_ns = interval_ms * (1000LL * 1000); 544 fuzz_ns = (interval_ns * SSH_KEYSTROKE_TIMING_FUZZ) / 100; 545 /* Center fuzz around requested interval */ 546 if (fuzz_ns > INT_MAX) 547 fuzz_ns = INT_MAX; 548 if (fuzz_ns > interval_ns) { 549 /* Shouldn't happen */ 550 fatal_f("internal error: fuzz %u%% %lldns > interval %lldns", 551 SSH_KEYSTROKE_TIMING_FUZZ, fuzz_ns, interval_ns); 552 } 553 /* 554 * Randomise the keystroke/chaff intervals in two ways: 555 * 1. Each interval has some random jitter applied to make the 556 * interval-to-interval time unpredictable. 557 * 2. The overall interval rate is also randomly perturbed for each 558 * chaffing session to make the average rate unpredictable. 559 */ 560 if (starting) 561 rate_fuzz = arc4random_uniform(fuzz_ns); 562 interval_ns -= fuzz_ns; 563 interval_ns += arc4random_uniform(fuzz_ns) + rate_fuzz; 564 565 tmp.tv_sec = interval_ns / (1000 * 1000 * 1000); 566 tmp.tv_nsec = interval_ns % (1000 * 1000 * 1000); 567 568 timespecadd(now, &tmp, next_interval); 569 } 570 571 /* 572 * Performs keystroke timing obfuscation. Returns non-zero if the 573 * output fd should be polled. 574 */ 575 static int 576 obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout, 577 int channel_did_enqueue) 578 { 579 static int active; 580 static struct timespec next_interval, chaff_until; 581 struct timespec now, tmp; 582 int just_started = 0, had_keystroke = 0; 583 static unsigned long long nchaff; 584 char *stop_reason = NULL; 585 long long n; 586 587 monotime_ts(&now); 588 589 if (options.obscure_keystroke_timing_interval <= 0) 590 return 1; /* disabled in config */ 591 592 if (!channel_still_open(ssh) || quit_pending) { 593 /* Stop if no channels left of we're waiting for one to close */ 594 stop_reason = "no active channels"; 595 } else if (ssh_packet_is_rekeying(ssh)) { 596 /* Stop if we're rekeying */ 597 stop_reason = "rekeying started"; 598 } else if (!ssh_packet_interactive_data_to_write(ssh) && 599 ssh_packet_have_data_to_write(ssh)) { 600 /* Stop if the output buffer has more than a few keystrokes */ 601 stop_reason = "output buffer filling"; 602 } else if (active && channel_did_enqueue && 603 ssh_packet_have_data_to_write(ssh)) { 604 /* Still in active mode and have a keystroke queued. */ 605 had_keystroke = 1; 606 } else if (active) { 607 if (timespeccmp(&now, &chaff_until, >=)) { 608 /* Stop if there have been no keystrokes for a while */ 609 stop_reason = "chaff time expired"; 610 } else if (timespeccmp(&now, &next_interval, >=)) { 611 /* Otherwise if we were due to send, then send chaff */ 612 if (send_chaff(ssh)) 613 nchaff++; 614 } 615 } 616 617 if (stop_reason != NULL) { 618 if (active) { 619 debug3_f("stopping: %s (%llu chaff packets sent)", 620 stop_reason, nchaff); 621 active = 0; 622 } 623 return 1; 624 } 625 626 /* 627 * If we're in interactive mode, and only have a small amount 628 * of outbound data, then we assume that the user is typing 629 * interactively. In this case, start quantising outbound packets to 630 * fixed time intervals to hide inter-keystroke timing. 631 */ 632 if (!active && ssh_packet_interactive_data_to_write(ssh) && 633 channel_did_enqueue && ssh_packet_have_data_to_write(ssh)) { 634 debug3_f("starting: interval ~%dms", 635 options.obscure_keystroke_timing_interval); 636 just_started = had_keystroke = active = 1; 637 nchaff = 0; 638 set_next_interval(&now, &next_interval, 639 options.obscure_keystroke_timing_interval, 1); 640 } 641 642 /* Don't hold off if obfuscation inactive */ 643 if (!active) 644 return 1; 645 646 if (had_keystroke) { 647 /* 648 * Arrange to send chaff packets for a random interval after 649 * the last keystroke was sent. 650 */ 651 ms_to_timespec(&tmp, SSH_KEYSTROKE_CHAFF_MIN_MS + 652 arc4random_uniform(SSH_KEYSTROKE_CHAFF_RNG_MS)); 653 timespecadd(&now, &tmp, &chaff_until); 654 } 655 656 ptimeout_deadline_monotime_tsp(timeout, &next_interval); 657 658 if (just_started) 659 return 1; 660 661 /* Don't arm output fd for poll until the timing interval has elapsed */ 662 if (timespeccmp(&now, &next_interval, <)) 663 return 0; 664 665 /* Calculate number of intervals missed since the last check */ 666 n = (now.tv_sec - next_interval.tv_sec) * 1000LL * 1000 * 1000; 667 n += now.tv_nsec - next_interval.tv_nsec; 668 n /= options.obscure_keystroke_timing_interval * 1000LL * 1000; 669 n = (n < 0) ? 1 : n + 1; 670 671 /* Advance to the next interval */ 672 set_next_interval(&now, &next_interval, 673 options.obscure_keystroke_timing_interval * n, 0); 674 return 1; 675 } 676 677 /* 678 * Waits until the client can do something (some data becomes available on 679 * one of the file descriptors). 680 */ 681 static void 682 client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp, 683 u_int *npfd_allocp, u_int *npfd_activep, int channel_did_enqueue, 684 int *conn_in_readyp, int *conn_out_readyp) 685 { 686 struct timespec timeout; 687 int ret, oready; 688 u_int p; 689 690 *conn_in_readyp = *conn_out_readyp = 0; 691 692 /* Prepare channel poll. First two pollfd entries are reserved */ 693 ptimeout_init(&timeout); 694 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 695 if (*npfd_activep < 2) 696 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 697 698 /* channel_prepare_poll could have closed the last channel */ 699 if (session_closed && !channel_still_open(ssh) && 700 !ssh_packet_have_data_to_write(ssh)) { 701 /* clear events since we did not call poll() */ 702 for (p = 0; p < *npfd_activep; p++) 703 (*pfdp)[p].revents = 0; 704 return; 705 } 706 707 oready = obfuscate_keystroke_timing(ssh, &timeout, channel_did_enqueue); 708 709 /* Monitor server connection on reserved pollfd entries */ 710 (*pfdp)[0].fd = connection_in; 711 (*pfdp)[0].events = POLLIN; 712 (*pfdp)[1].fd = connection_out; 713 (*pfdp)[1].events = (oready && ssh_packet_have_data_to_write(ssh)) ? 714 POLLOUT : 0; 715 716 /* 717 * Wait for something to happen. This will suspend the process until 718 * some polled descriptor can be read, written, or has some other 719 * event pending, or a timeout expires. 720 */ 721 set_control_persist_exit_time(ssh); 722 if (control_persist_exit_time > 0) 723 ptimeout_deadline_monotime(&timeout, control_persist_exit_time); 724 if (options.server_alive_interval > 0) 725 ptimeout_deadline_monotime(&timeout, server_alive_time); 726 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 727 ptimeout_deadline_sec(&timeout, 728 ssh_packet_get_rekey_timeout(ssh)); 729 } 730 731 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), NULL); 732 733 if (ret == -1) { 734 /* 735 * We have to clear the events because we return. 736 * We have to return, because the mainloop checks for the flags 737 * set by the signal handlers. 738 */ 739 for (p = 0; p < *npfd_activep; p++) 740 (*pfdp)[p].revents = 0; 741 if (errno == EINTR) 742 return; 743 /* Note: we might still have data in the buffers. */ 744 quit_message("poll: %s", strerror(errno)); 745 return; 746 } 747 748 *conn_in_readyp = (*pfdp)[0].revents != 0; 749 *conn_out_readyp = (*pfdp)[1].revents != 0; 750 751 if (options.server_alive_interval > 0 && !*conn_in_readyp && 752 monotime() >= server_alive_time) { 753 /* 754 * ServerAlive check is needed. We can't rely on the poll 755 * timing out since traffic on the client side such as port 756 * forwards can keep waking it up. 757 */ 758 server_alive_check(ssh); 759 } 760 } 761 762 static void 763 client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr) 764 { 765 /* Flush stdout and stderr buffers. */ 766 if (sshbuf_len(bout) > 0) 767 atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout), 768 sshbuf_len(bout)); 769 if (sshbuf_len(berr) > 0) 770 atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr), 771 sshbuf_len(berr)); 772 773 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 774 775 sshbuf_reset(bin); 776 sshbuf_reset(bout); 777 sshbuf_reset(berr); 778 779 /* Send the suspend signal to the program itself. */ 780 kill(getpid(), SIGTSTP); 781 782 /* Reset window sizes in case they have changed */ 783 received_window_change_signal = 1; 784 785 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 786 } 787 788 static void 789 client_process_net_input(struct ssh *ssh) 790 { 791 int r; 792 793 /* 794 * Read input from the server, and add any such data to the buffer of 795 * the packet subsystem. 796 */ 797 schedule_server_alive_check(); 798 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 799 return; /* success */ 800 if (r == SSH_ERR_SYSTEM_ERROR) { 801 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK) 802 return; 803 if (errno == EPIPE) { 804 quit_message("Connection to %s closed by remote host.", 805 host); 806 return; 807 } 808 } 809 quit_message("Read from remote host %s: %s", host, ssh_err(r)); 810 } 811 812 static void 813 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) 814 { 815 struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; 816 char errmsg[256]; 817 int r, tochan; 818 819 /* 820 * If a TTY was explicitly requested, then a failure to allocate 821 * one is fatal. 822 */ 823 if (cr->action == CONFIRM_TTY && 824 (options.request_tty == REQUEST_TTY_FORCE || 825 options.request_tty == REQUEST_TTY_YES)) 826 cr->action = CONFIRM_CLOSE; 827 828 /* XXX suppress on mux _client_ quietmode */ 829 tochan = options.log_level >= SYSLOG_LEVEL_ERROR && 830 c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; 831 832 if (type == SSH2_MSG_CHANNEL_SUCCESS) { 833 debug2("%s request accepted on channel %d", 834 cr->request_type, c->self); 835 } else if (type == SSH2_MSG_CHANNEL_FAILURE) { 836 if (tochan) { 837 snprintf(errmsg, sizeof(errmsg), 838 "%s request failed\r\n", cr->request_type); 839 } else { 840 snprintf(errmsg, sizeof(errmsg), 841 "%s request failed on channel %d", 842 cr->request_type, c->self); 843 } 844 /* If error occurred on primary session channel, then exit */ 845 if (cr->action == CONFIRM_CLOSE && c->self == session_ident) 846 fatal("%s", errmsg); 847 /* 848 * If error occurred on mux client, append to 849 * their stderr. 850 */ 851 if (tochan) { 852 debug3_f("channel %d: mux request: %s", c->self, 853 cr->request_type); 854 if ((r = sshbuf_put(c->extended, errmsg, 855 strlen(errmsg))) != 0) 856 fatal_fr(r, "sshbuf_put"); 857 } else 858 error("%s", errmsg); 859 if (cr->action == CONFIRM_TTY) { 860 /* 861 * If a TTY allocation error occurred, then arrange 862 * for the correct TTY to leave raw mode. 863 */ 864 if (c->self == session_ident) 865 leave_raw_mode(0); 866 else 867 mux_tty_alloc_failed(ssh, c); 868 } else if (cr->action == CONFIRM_CLOSE) { 869 chan_read_failed(ssh, c); 870 chan_write_failed(ssh, c); 871 } 872 } 873 free(cr); 874 } 875 876 static void 877 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) 878 { 879 free(ctx); 880 } 881 882 void 883 client_expect_confirm(struct ssh *ssh, int id, const char *request, 884 enum confirm_action action) 885 { 886 struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); 887 888 cr->request_type = request; 889 cr->action = action; 890 891 channel_register_status_confirm(ssh, id, client_status_confirm, 892 client_abandon_status_confirm, cr); 893 } 894 895 void 896 client_register_global_confirm(global_confirm_cb *cb, void *ctx) 897 { 898 struct global_confirm *gc, *last_gc; 899 900 /* Coalesce identical callbacks */ 901 last_gc = TAILQ_LAST(&global_confirms, global_confirms); 902 if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { 903 if (++last_gc->ref_count >= INT_MAX) 904 fatal_f("last_gc->ref_count = %d", 905 last_gc->ref_count); 906 return; 907 } 908 909 gc = xcalloc(1, sizeof(*gc)); 910 gc->cb = cb; 911 gc->ctx = ctx; 912 gc->ref_count = 1; 913 TAILQ_INSERT_TAIL(&global_confirms, gc, entry); 914 } 915 916 /* 917 * Returns non-zero if the client is able to handle a hostkeys-00@openssh.com 918 * hostkey update request. 919 */ 920 static int 921 can_update_hostkeys(void) 922 { 923 if (hostkeys_update_complete) 924 return 0; 925 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && 926 options.batch_mode) 927 return 0; /* won't ask in batchmode, so don't even try */ 928 if (!options.update_hostkeys || options.num_user_hostfiles <= 0) 929 return 0; 930 return 1; 931 } 932 933 static void 934 client_repledge(void) 935 { 936 debug3_f("enter"); 937 938 /* Might be able to tighten pledge now that session is established */ 939 if (options.control_master || options.control_path != NULL || 940 options.forward_x11 || options.fork_after_authentication || 941 can_update_hostkeys() || 942 (session_ident != -1 && !session_setup_complete)) { 943 /* Can't tighten */ 944 return; 945 } 946 /* 947 * LocalCommand and UpdateHostkeys have finished, so can get rid of 948 * filesystem. 949 * 950 * XXX protocol allows a server can to change hostkeys during the 951 * connection at rekey time that could trigger a hostkeys update 952 * but AFAIK no implementations support this. Could improve by 953 * forcing known_hosts to be read-only or via unveil(2). 954 */ 955 if (options.num_local_forwards != 0 || 956 options.num_remote_forwards != 0 || 957 options.num_permitted_remote_opens != 0 || 958 options.enable_escape_commandline != 0) { 959 /* rfwd needs inet */ 960 debug("pledge: network"); 961 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 962 fatal_f("pledge(): %s", strerror(errno)); 963 } else if (options.forward_agent != 0) { 964 /* agent forwarding needs to open $SSH_AUTH_SOCK at will */ 965 debug("pledge: agent"); 966 if (pledge("stdio unix proc tty", NULL) == -1) 967 fatal_f("pledge(): %s", strerror(errno)); 968 } else { 969 debug("pledge: fork"); 970 if (pledge("stdio proc tty", NULL) == -1) 971 fatal_f("pledge(): %s", strerror(errno)); 972 } 973 /* XXX further things to do: 974 * 975 * - might be able to get rid of proc if we kill ~^Z 976 * - ssh -N (no session) 977 * - stdio forwarding 978 * - sessions without tty 979 */ 980 } 981 982 static void 983 process_cmdline(struct ssh *ssh) 984 { 985 void (*handler)(int); 986 char *s, *cmd; 987 int ok, delete = 0, local = 0, remote = 0, dynamic = 0; 988 struct Forward fwd; 989 990 memset(&fwd, 0, sizeof(fwd)); 991 992 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 993 handler = ssh_signal(SIGINT, SIG_IGN); 994 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); 995 if (s == NULL) 996 goto out; 997 while (isspace((u_char)*s)) 998 s++; 999 if (*s == '-') 1000 s++; /* Skip cmdline '-', if any */ 1001 if (*s == '\0') 1002 goto out; 1003 1004 if (*s == 'h' || *s == 'H' || *s == '?') { 1005 logit("Commands:"); 1006 logit(" -L[bind_address:]port:host:hostport " 1007 "Request local forward"); 1008 logit(" -R[bind_address:]port:host:hostport " 1009 "Request remote forward"); 1010 logit(" -D[bind_address:]port " 1011 "Request dynamic forward"); 1012 logit(" -KL[bind_address:]port " 1013 "Cancel local forward"); 1014 logit(" -KR[bind_address:]port " 1015 "Cancel remote forward"); 1016 logit(" -KD[bind_address:]port " 1017 "Cancel dynamic forward"); 1018 if (!options.permit_local_command) 1019 goto out; 1020 logit(" !args " 1021 "Execute local command"); 1022 goto out; 1023 } 1024 1025 if (*s == '!' && options.permit_local_command) { 1026 s++; 1027 ssh_local_cmd(s); 1028 goto out; 1029 } 1030 1031 if (*s == 'K') { 1032 delete = 1; 1033 s++; 1034 } 1035 if (*s == 'L') 1036 local = 1; 1037 else if (*s == 'R') 1038 remote = 1; 1039 else if (*s == 'D') 1040 dynamic = 1; 1041 else { 1042 logit("Invalid command."); 1043 goto out; 1044 } 1045 1046 while (isspace((u_char)*++s)) 1047 ; 1048 1049 /* XXX update list of forwards in options */ 1050 if (delete) { 1051 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ 1052 if (!parse_forward(&fwd, s, 1, 0)) { 1053 logit("Bad forwarding close specification."); 1054 goto out; 1055 } 1056 if (remote) 1057 ok = channel_request_rforward_cancel(ssh, &fwd) == 0; 1058 else if (dynamic) 1059 ok = channel_cancel_lport_listener(ssh, &fwd, 1060 0, &options.fwd_opts) > 0; 1061 else 1062 ok = channel_cancel_lport_listener(ssh, &fwd, 1063 CHANNEL_CANCEL_PORT_STATIC, 1064 &options.fwd_opts) > 0; 1065 if (!ok) { 1066 logit("Unknown port forwarding."); 1067 goto out; 1068 } 1069 logit("Canceled forwarding."); 1070 } else { 1071 /* -R specs can be both dynamic or not, so check both. */ 1072 if (remote) { 1073 if (!parse_forward(&fwd, s, 0, remote) && 1074 !parse_forward(&fwd, s, 1, remote)) { 1075 logit("Bad remote forwarding specification."); 1076 goto out; 1077 } 1078 } else if (!parse_forward(&fwd, s, dynamic, remote)) { 1079 logit("Bad local forwarding specification."); 1080 goto out; 1081 } 1082 if (local || dynamic) { 1083 if (!channel_setup_local_fwd_listener(ssh, &fwd, 1084 &options.fwd_opts)) { 1085 logit("Port forwarding failed."); 1086 goto out; 1087 } 1088 } else { 1089 if (channel_request_remote_forwarding(ssh, &fwd) < 0) { 1090 logit("Port forwarding failed."); 1091 goto out; 1092 } 1093 } 1094 logit("Forwarding port."); 1095 } 1096 1097 out: 1098 ssh_signal(SIGINT, handler); 1099 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1100 free(cmd); 1101 free(fwd.listen_host); 1102 free(fwd.listen_path); 1103 free(fwd.connect_host); 1104 free(fwd.connect_path); 1105 } 1106 1107 /* reasons to suppress output of an escape command in help output */ 1108 #define SUPPRESS_NEVER 0 /* never suppress, always show */ 1109 #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ 1110 #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ 1111 #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ 1112 #define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/ 1113 struct escape_help_text { 1114 const char *cmd; 1115 const char *text; 1116 unsigned int flags; 1117 }; 1118 static struct escape_help_text esc_txt[] = { 1119 {".", "terminate session", SUPPRESS_MUXMASTER}, 1120 {".", "terminate connection (and any multiplexed sessions)", 1121 SUPPRESS_MUXCLIENT}, 1122 {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, 1123 {"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE}, 1124 {"R", "request rekey", SUPPRESS_NEVER}, 1125 {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, 1126 {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, 1127 {"#", "list forwarded connections", SUPPRESS_NEVER}, 1128 {"&", "background ssh (when waiting for connections to terminate)", 1129 SUPPRESS_MUXCLIENT}, 1130 {"?", "this message", SUPPRESS_NEVER}, 1131 }; 1132 1133 static void 1134 print_escape_help(struct sshbuf *b, int escape_char, int mux_client, 1135 int using_stderr) 1136 { 1137 unsigned int i, suppress_flags; 1138 int r; 1139 1140 if ((r = sshbuf_putf(b, 1141 "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0) 1142 fatal_fr(r, "sshbuf_putf"); 1143 1144 suppress_flags = 1145 (mux_client ? SUPPRESS_MUXCLIENT : 0) | 1146 (mux_client ? 0 : SUPPRESS_MUXMASTER) | 1147 (using_stderr ? 0 : SUPPRESS_SYSLOG) | 1148 (options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0); 1149 1150 for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { 1151 if (esc_txt[i].flags & suppress_flags) 1152 continue; 1153 if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n", 1154 escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0) 1155 fatal_fr(r, "sshbuf_putf"); 1156 } 1157 1158 if ((r = sshbuf_putf(b, 1159 " %c%c - send the escape character by typing it twice\r\n" 1160 "(Note that escapes are only recognized immediately after " 1161 "newline.)\r\n", escape_char, escape_char)) != 0) 1162 fatal_fr(r, "sshbuf_putf"); 1163 } 1164 1165 /* 1166 * Process the characters one by one. 1167 */ 1168 static int 1169 process_escapes(struct ssh *ssh, Channel *c, 1170 struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr, 1171 char *buf, int len) 1172 { 1173 pid_t pid; 1174 int r, bytes = 0; 1175 u_int i; 1176 u_char ch; 1177 char *s; 1178 struct escape_filter_ctx *efc; 1179 1180 if (c == NULL || c->filter_ctx == NULL || len <= 0) 1181 return 0; 1182 1183 efc = (struct escape_filter_ctx *)c->filter_ctx; 1184 1185 for (i = 0; i < (u_int)len; i++) { 1186 /* Get one character at a time. */ 1187 ch = buf[i]; 1188 1189 if (efc->escape_pending) { 1190 /* We have previously seen an escape character. */ 1191 /* Clear the flag now. */ 1192 efc->escape_pending = 0; 1193 1194 /* Process the escaped character. */ 1195 switch (ch) { 1196 case '.': 1197 /* Terminate the connection. */ 1198 if ((r = sshbuf_putf(berr, "%c.\r\n", 1199 efc->escape_char)) != 0) 1200 fatal_fr(r, "sshbuf_putf"); 1201 if (c && c->ctl_chan != -1) { 1202 channel_force_close(ssh, c, 1); 1203 return 0; 1204 } else 1205 quit_pending = 1; 1206 return -1; 1207 1208 case 'Z' - 64: 1209 /* XXX support this for mux clients */ 1210 if (c && c->ctl_chan != -1) { 1211 char b[16]; 1212 noescape: 1213 if (ch == 'Z' - 64) 1214 snprintf(b, sizeof b, "^Z"); 1215 else 1216 snprintf(b, sizeof b, "%c", ch); 1217 if ((r = sshbuf_putf(berr, 1218 "%c%s escape not available to " 1219 "multiplexed sessions\r\n", 1220 efc->escape_char, b)) != 0) 1221 fatal_fr(r, "sshbuf_putf"); 1222 continue; 1223 } 1224 /* Suspend the program. Inform the user */ 1225 if ((r = sshbuf_putf(berr, 1226 "%c^Z [suspend ssh]\r\n", 1227 efc->escape_char)) != 0) 1228 fatal_fr(r, "sshbuf_putf"); 1229 1230 /* Restore terminal modes and suspend. */ 1231 client_suspend_self(bin, bout, berr); 1232 1233 /* We have been continued. */ 1234 continue; 1235 1236 case 'B': 1237 if ((r = sshbuf_putf(berr, 1238 "%cB\r\n", efc->escape_char)) != 0) 1239 fatal_fr(r, "sshbuf_putf"); 1240 channel_request_start(ssh, c->self, "break", 0); 1241 if ((r = sshpkt_put_u32(ssh, 1000)) != 0 || 1242 (r = sshpkt_send(ssh)) != 0) 1243 fatal_fr(r, "send packet"); 1244 continue; 1245 1246 case 'R': 1247 if (ssh->compat & SSH_BUG_NOREKEY) 1248 logit("Server does not " 1249 "support re-keying"); 1250 else 1251 need_rekeying = 1; 1252 continue; 1253 1254 case 'V': 1255 /* FALLTHROUGH */ 1256 case 'v': 1257 if (c && c->ctl_chan != -1) 1258 goto noescape; 1259 if (!log_is_on_stderr()) { 1260 if ((r = sshbuf_putf(berr, 1261 "%c%c [Logging to syslog]\r\n", 1262 efc->escape_char, ch)) != 0) 1263 fatal_fr(r, "sshbuf_putf"); 1264 continue; 1265 } 1266 if (ch == 'V' && options.log_level > 1267 SYSLOG_LEVEL_QUIET) 1268 log_change_level(--options.log_level); 1269 if (ch == 'v' && options.log_level < 1270 SYSLOG_LEVEL_DEBUG3) 1271 log_change_level(++options.log_level); 1272 if ((r = sshbuf_putf(berr, 1273 "%c%c [LogLevel %s]\r\n", 1274 efc->escape_char, ch, 1275 log_level_name(options.log_level))) != 0) 1276 fatal_fr(r, "sshbuf_putf"); 1277 continue; 1278 1279 case '&': 1280 if (c->ctl_chan != -1) 1281 goto noescape; 1282 /* 1283 * Detach the program (continue to serve 1284 * connections, but put in background and no 1285 * more new connections). 1286 */ 1287 /* Restore tty modes. */ 1288 leave_raw_mode( 1289 options.request_tty == REQUEST_TTY_FORCE); 1290 1291 /* Stop listening for new connections. */ 1292 channel_stop_listening(ssh); 1293 1294 if ((r = sshbuf_putf(berr, "%c& " 1295 "[backgrounded]\n", efc->escape_char)) != 0) 1296 fatal_fr(r, "sshbuf_putf"); 1297 1298 /* Fork into background. */ 1299 pid = fork(); 1300 if (pid == -1) { 1301 error("fork: %.100s", strerror(errno)); 1302 continue; 1303 } 1304 if (pid != 0) { /* This is the parent. */ 1305 /* The parent just exits. */ 1306 exit(0); 1307 } 1308 /* The child continues serving connections. */ 1309 /* fake EOF on stdin */ 1310 if ((r = sshbuf_put_u8(bin, 4)) != 0) 1311 fatal_fr(r, "sshbuf_put_u8"); 1312 return -1; 1313 case '?': 1314 print_escape_help(berr, efc->escape_char, 1315 (c && c->ctl_chan != -1), 1316 log_is_on_stderr()); 1317 continue; 1318 1319 case '#': 1320 if ((r = sshbuf_putf(berr, "%c#\r\n", 1321 efc->escape_char)) != 0) 1322 fatal_fr(r, "sshbuf_putf"); 1323 s = channel_open_message(ssh); 1324 if ((r = sshbuf_put(berr, s, strlen(s))) != 0) 1325 fatal_fr(r, "sshbuf_put"); 1326 free(s); 1327 continue; 1328 1329 case 'C': 1330 if (c && c->ctl_chan != -1) 1331 goto noescape; 1332 if (options.enable_escape_commandline == 0) { 1333 if ((r = sshbuf_putf(berr, 1334 "commandline disabled\r\n")) != 0) 1335 fatal_fr(r, "sshbuf_putf"); 1336 continue; 1337 } 1338 process_cmdline(ssh); 1339 continue; 1340 1341 default: 1342 if (ch != efc->escape_char) { 1343 if ((r = sshbuf_put_u8(bin, 1344 efc->escape_char)) != 0) 1345 fatal_fr(r, "sshbuf_put_u8"); 1346 bytes++; 1347 } 1348 /* Escaped characters fall through here */ 1349 break; 1350 } 1351 } else { 1352 /* 1353 * The previous character was not an escape char. 1354 * Check if this is an escape. 1355 */ 1356 if (last_was_cr && ch == efc->escape_char) { 1357 /* 1358 * It is. Set the flag and continue to 1359 * next character. 1360 */ 1361 efc->escape_pending = 1; 1362 continue; 1363 } 1364 } 1365 1366 /* 1367 * Normal character. Record whether it was a newline, 1368 * and append it to the buffer. 1369 */ 1370 last_was_cr = (ch == '\r' || ch == '\n'); 1371 if ((r = sshbuf_put_u8(bin, ch)) != 0) 1372 fatal_fr(r, "sshbuf_put_u8"); 1373 bytes++; 1374 } 1375 return bytes; 1376 } 1377 1378 /* 1379 * Get packets from the connection input buffer, and process them as long as 1380 * there are packets available. 1381 * 1382 * Any unknown packets received during the actual 1383 * session cause the session to terminate. This is 1384 * intended to make debugging easier since no 1385 * confirmations are sent. Any compatible protocol 1386 * extensions must be negotiated during the 1387 * preparatory phase. 1388 */ 1389 1390 static void 1391 client_process_buffered_input_packets(struct ssh *ssh) 1392 { 1393 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending); 1394 } 1395 1396 /* scan buf[] for '~' before sending data to the peer */ 1397 1398 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ 1399 void * 1400 client_new_escape_filter_ctx(int escape_char) 1401 { 1402 struct escape_filter_ctx *ret; 1403 1404 ret = xcalloc(1, sizeof(*ret)); 1405 ret->escape_pending = 0; 1406 ret->escape_char = escape_char; 1407 return (void *)ret; 1408 } 1409 1410 /* Free the escape filter context on channel free */ 1411 void 1412 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) 1413 { 1414 free(ctx); 1415 } 1416 1417 int 1418 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, 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 1452 debug("Entering interactive session."); 1453 session_ident = ssh2_chan_id; 1454 1455 if (options.control_master && 1456 !option_clear_or_none(options.control_path)) { 1457 debug("pledge: id"); 1458 if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty", 1459 NULL) == -1) 1460 fatal_f("pledge(): %s", strerror(errno)); 1461 1462 } else if (options.forward_x11 || options.permit_local_command) { 1463 debug("pledge: exec"); 1464 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty", 1465 NULL) == -1) 1466 fatal_f("pledge(): %s", strerror(errno)); 1467 1468 } else if (options.update_hostkeys) { 1469 debug("pledge: filesystem"); 1470 if (pledge("stdio rpath wpath cpath unix inet dns proc tty", 1471 NULL) == -1) 1472 fatal_f("pledge(): %s", strerror(errno)); 1473 1474 } else if (!option_clear_or_none(options.proxy_command) || 1475 options.fork_after_authentication) { 1476 debug("pledge: proc"); 1477 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1) 1478 fatal_f("pledge(): %s", strerror(errno)); 1479 1480 } else { 1481 debug("pledge: network"); 1482 if (pledge("stdio unix inet dns proc tty", NULL) == -1) 1483 fatal_f("pledge(): %s", strerror(errno)); 1484 } 1485 1486 /* might be able to tighten now */ 1487 client_repledge(); 1488 1489 start_time = monotime_double(); 1490 1491 /* Initialize variables. */ 1492 last_was_cr = 1; 1493 exit_status = -1; 1494 connection_in = ssh_packet_get_connection_in(ssh); 1495 connection_out = ssh_packet_get_connection_out(ssh); 1496 1497 quit_pending = 0; 1498 1499 /* Initialize buffer. */ 1500 if ((stderr_buffer = sshbuf_new()) == NULL) 1501 fatal_f("sshbuf_new failed"); 1502 1503 client_init_dispatch(ssh); 1504 1505 /* 1506 * Set signal handlers, (e.g. to restore non-blocking mode) 1507 * but don't overwrite SIG_IGN, matches behaviour from rsh(1) 1508 */ 1509 if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN) 1510 ssh_signal(SIGHUP, signal_handler); 1511 if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN) 1512 ssh_signal(SIGINT, signal_handler); 1513 if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN) 1514 ssh_signal(SIGQUIT, signal_handler); 1515 if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN) 1516 ssh_signal(SIGTERM, signal_handler); 1517 ssh_signal(SIGWINCH, window_change_handler); 1518 1519 if (have_pty) 1520 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1521 1522 if (session_ident != -1) { 1523 if (escape_char_arg != SSH_ESCAPECHAR_NONE) { 1524 channel_register_filter(ssh, session_ident, 1525 client_simple_escape_filter, NULL, 1526 client_filter_cleanup, 1527 client_new_escape_filter_ctx( 1528 escape_char_arg)); 1529 } 1530 channel_register_cleanup(ssh, session_ident, 1531 client_channel_closed, 0); 1532 } 1533 1534 schedule_server_alive_check(); 1535 1536 /* Main loop of the client for the interactive session mode. */ 1537 while (!quit_pending) { 1538 channel_did_enqueue = 0; 1539 1540 /* Process buffered packets sent by the server. */ 1541 client_process_buffered_input_packets(ssh); 1542 1543 if (session_closed && !channel_still_open(ssh)) 1544 break; 1545 1546 if (ssh_packet_is_rekeying(ssh)) { 1547 debug("rekeying in progress"); 1548 } else if (need_rekeying) { 1549 /* manual rekey request */ 1550 debug("need rekeying"); 1551 if ((r = kex_start_rekex(ssh)) != 0) 1552 fatal_fr(r, "kex_start_rekex"); 1553 need_rekeying = 0; 1554 } else { 1555 /* 1556 * Make packets from buffered channel data, and 1557 * enqueue them for sending to the server. 1558 */ 1559 if (ssh_packet_not_very_much_data_to_write(ssh)) 1560 channel_did_enqueue = channel_output_poll(ssh); 1561 1562 /* 1563 * Check if the window size has changed, and buffer a 1564 * message about it to the server if so. 1565 */ 1566 client_check_window_change(ssh); 1567 1568 if (quit_pending) 1569 break; 1570 } 1571 /* 1572 * Wait until we have something to do (something becomes 1573 * available on one of the descriptors). 1574 */ 1575 client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc, 1576 &npfd_active, channel_did_enqueue, 1577 &conn_in_ready, &conn_out_ready); 1578 1579 if (quit_pending) 1580 break; 1581 1582 /* Do channel operations. */ 1583 channel_after_poll(ssh, pfd, npfd_active); 1584 1585 /* Buffer input from the connection. */ 1586 if (conn_in_ready) 1587 client_process_net_input(ssh); 1588 1589 if (quit_pending) 1590 break; 1591 1592 /* A timeout may have triggered rekeying */ 1593 if ((r = ssh_packet_check_rekey(ssh)) != 0) 1594 fatal_fr(r, "cannot start rekeying"); 1595 1596 /* 1597 * Send as much buffered packet data as possible to the 1598 * sender. 1599 */ 1600 if (conn_out_ready) { 1601 if ((r = ssh_packet_write_poll(ssh)) != 0) { 1602 sshpkt_fatal(ssh, r, 1603 "%s: ssh_packet_write_poll", __func__); 1604 } 1605 } 1606 1607 /* 1608 * If we are a backgrounded control master, and the 1609 * timeout has expired without any active client 1610 * connections, then quit. 1611 */ 1612 if (control_persist_exit_time > 0) { 1613 if (monotime() >= control_persist_exit_time) { 1614 debug("ControlPersist timeout expired"); 1615 break; 1616 } 1617 } 1618 } 1619 free(pfd); 1620 1621 /* Terminate the session. */ 1622 1623 /* Stop watching for window change. */ 1624 ssh_signal(SIGWINCH, SIG_DFL); 1625 1626 if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || 1627 (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 || 1628 (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 || 1629 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */ 1630 (r = sshpkt_send(ssh)) != 0 || 1631 (r = ssh_packet_write_wait(ssh)) != 0) 1632 fatal_fr(r, "send disconnect"); 1633 1634 channel_free_all(ssh); 1635 1636 if (have_pty) 1637 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1638 1639 /* 1640 * If there was no shell or command requested, there will be no remote 1641 * exit status to be returned. In that case, clear error code if the 1642 * connection was deliberately terminated at this end. 1643 */ 1644 if (options.session_type == SESSION_TYPE_NONE && 1645 received_signal == SIGTERM) { 1646 received_signal = 0; 1647 exit_status = 0; 1648 } 1649 1650 if (received_signal) { 1651 verbose("Killed by signal %d.", (int) received_signal); 1652 cleanup_exit(255); 1653 } 1654 1655 /* 1656 * In interactive mode (with pseudo tty) display a message indicating 1657 * that the connection has been closed. 1658 */ 1659 if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO) 1660 quit_message("Connection to %s closed.", host); 1661 1662 /* Output any buffered data for stderr. */ 1663 if (sshbuf_len(stderr_buffer) > 0) { 1664 len = atomicio(vwrite, fileno(stderr), 1665 (u_char *)sshbuf_ptr(stderr_buffer), 1666 sshbuf_len(stderr_buffer)); 1667 if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer)) 1668 error("Write failed flushing stderr buffer."); 1669 else if ((r = sshbuf_consume(stderr_buffer, len)) != 0) 1670 fatal_fr(r, "sshbuf_consume"); 1671 } 1672 1673 /* Clear and free any buffers. */ 1674 sshbuf_free(stderr_buffer); 1675 1676 /* Report bytes transferred, and transfer rates. */ 1677 total_time = monotime_double() - start_time; 1678 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1679 verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", 1680 (unsigned long long)obytes, (unsigned long long)ibytes, total_time); 1681 if (total_time > 0) 1682 verbose("Bytes per second: sent %.1f, received %.1f", 1683 obytes / total_time, ibytes / total_time); 1684 /* Return the exit status of the program. */ 1685 debug("Exit status %d", exit_status); 1686 return exit_status; 1687 } 1688 1689 /*********/ 1690 1691 static Channel * 1692 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, 1693 int rchan, u_int rwindow, u_int rmaxpack) 1694 { 1695 Channel *c = NULL; 1696 struct sshbuf *b = NULL; 1697 char *listen_address, *originator_address; 1698 u_int listen_port, originator_port; 1699 int r; 1700 1701 /* Get rest of the packet */ 1702 if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 || 1703 (r = sshpkt_get_u32(ssh, &listen_port)) != 0 || 1704 (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 || 1705 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1706 (r = sshpkt_get_end(ssh)) != 0) 1707 fatal_fr(r, "parse packet"); 1708 1709 debug_f("listen %s port %d, originator %s port %d", 1710 listen_address, listen_port, originator_address, originator_port); 1711 1712 if (listen_port > 0xffff) 1713 error_f("invalid listen port"); 1714 else if (originator_port > 0xffff) 1715 error_f("invalid originator port"); 1716 else { 1717 c = channel_connect_by_listen_address(ssh, 1718 listen_address, listen_port, "forwarded-tcpip", 1719 originator_address); 1720 } 1721 1722 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1723 if ((b = sshbuf_new()) == NULL) { 1724 error_f("alloc reply"); 1725 goto out; 1726 } 1727 /* reconstruct and send to muxclient */ 1728 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ 1729 (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1730 (r = sshbuf_put_cstring(b, request_type)) != 0 || 1731 (r = sshbuf_put_u32(b, rchan)) != 0 || 1732 (r = sshbuf_put_u32(b, rwindow)) != 0 || 1733 (r = sshbuf_put_u32(b, rmaxpack)) != 0 || 1734 (r = sshbuf_put_cstring(b, listen_address)) != 0 || 1735 (r = sshbuf_put_u32(b, listen_port)) != 0 || 1736 (r = sshbuf_put_cstring(b, originator_address)) != 0 || 1737 (r = sshbuf_put_u32(b, originator_port)) != 0 || 1738 (r = sshbuf_put_stringb(c->output, b)) != 0) { 1739 error_fr(r, "compose for muxclient"); 1740 goto out; 1741 } 1742 } 1743 1744 out: 1745 sshbuf_free(b); 1746 free(originator_address); 1747 free(listen_address); 1748 return c; 1749 } 1750 1751 static Channel * 1752 client_request_forwarded_streamlocal(struct ssh *ssh, 1753 const char *request_type, int rchan) 1754 { 1755 Channel *c = NULL; 1756 char *listen_path; 1757 int r; 1758 1759 /* Get the remote path. */ 1760 if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 || 1761 (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */ 1762 (r = sshpkt_get_end(ssh)) != 0) 1763 fatal_fr(r, "parse packet"); 1764 1765 debug_f("request: %s", listen_path); 1766 1767 c = channel_connect_by_listen_path(ssh, listen_path, 1768 "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); 1769 free(listen_path); 1770 return c; 1771 } 1772 1773 static Channel * 1774 client_request_x11(struct ssh *ssh, const char *request_type, int rchan) 1775 { 1776 Channel *c = NULL; 1777 char *originator; 1778 u_int originator_port; 1779 int r, sock; 1780 1781 if (!options.forward_x11) { 1782 error("Warning: ssh server tried X11 forwarding."); 1783 error("Warning: this is probably a break-in attempt by a " 1784 "malicious server."); 1785 return NULL; 1786 } 1787 if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) { 1788 verbose("Rejected X11 connection after ForwardX11Timeout " 1789 "expired"); 1790 return NULL; 1791 } 1792 if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 1793 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 1794 (r = sshpkt_get_end(ssh)) != 0) 1795 fatal_fr(r, "parse packet"); 1796 /* XXX check permission */ 1797 /* XXX range check originator port? */ 1798 debug("client_request_x11: request from %s %u", originator, 1799 originator_port); 1800 free(originator); 1801 sock = x11_connect_display(ssh); 1802 if (sock < 0) 1803 return NULL; 1804 c = channel_new(ssh, "x11", 1805 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 1806 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); 1807 c->force_drain = 1; 1808 return c; 1809 } 1810 1811 static Channel * 1812 client_request_agent(struct ssh *ssh, const char *request_type, int rchan) 1813 { 1814 Channel *c = NULL; 1815 int r, sock; 1816 1817 if (!options.forward_agent) { 1818 error("Warning: ssh server tried agent forwarding."); 1819 error("Warning: this is probably a break-in attempt by a " 1820 "malicious server."); 1821 return NULL; 1822 } 1823 if (forward_agent_sock_path == NULL) { 1824 r = ssh_get_authentication_socket(&sock); 1825 } else { 1826 r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock); 1827 } 1828 if (r != 0) { 1829 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1830 debug_fr(r, "ssh_get_authentication_socket"); 1831 return NULL; 1832 } 1833 if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey, 1834 ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0) 1835 debug_f("bound agent to hostkey"); 1836 else 1837 debug2_fr(r, "ssh_agent_bind_hostkey"); 1838 1839 c = channel_new(ssh, "authentication agent connection", 1840 SSH_CHANNEL_OPEN, sock, sock, -1, 1841 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1842 "authentication agent connection", 1); 1843 c->force_drain = 1; 1844 return c; 1845 } 1846 1847 char * 1848 client_request_tun_fwd(struct ssh *ssh, int tun_mode, 1849 int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx) 1850 { 1851 Channel *c; 1852 int r, fd; 1853 char *ifname = NULL; 1854 1855 if (tun_mode == SSH_TUNMODE_NO) 1856 return 0; 1857 1858 debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); 1859 1860 /* Open local tunnel device */ 1861 if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) { 1862 error("Tunnel device open failed."); 1863 return NULL; 1864 } 1865 debug("Tunnel forwarding using interface %s", ifname); 1866 1867 c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1, 1868 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1869 c->datagram = 1; 1870 1871 #if defined(SSH_TUN_FILTER) 1872 if (options.tun_open == SSH_TUNMODE_POINTOPOINT) 1873 channel_register_filter(ssh, c->self, sys_tun_infilter, 1874 sys_tun_outfilter, NULL, NULL); 1875 #endif 1876 1877 if (cb != NULL) 1878 channel_register_open_confirm(ssh, c->self, cb, cbctx); 1879 1880 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || 1881 (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 || 1882 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1883 (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 || 1884 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1885 (r = sshpkt_put_u32(ssh, tun_mode)) != 0 || 1886 (r = sshpkt_put_u32(ssh, remote_tun)) != 0 || 1887 (r = sshpkt_send(ssh)) != 0) 1888 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1889 1890 return ifname; 1891 } 1892 1893 /* XXXX move to generic input handler */ 1894 static int 1895 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 1896 { 1897 Channel *c = NULL; 1898 char *ctype = NULL; 1899 int r; 1900 u_int rchan; 1901 size_t len; 1902 u_int rmaxpack, rwindow; 1903 1904 if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 || 1905 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 1906 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 1907 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 1908 goto out; 1909 1910 debug("client_input_channel_open: ctype %s rchan %d win %d max %d", 1911 ctype, rchan, rwindow, rmaxpack); 1912 1913 if (strcmp(ctype, "forwarded-tcpip") == 0) { 1914 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, 1915 rmaxpack); 1916 } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { 1917 c = client_request_forwarded_streamlocal(ssh, ctype, rchan); 1918 } else if (strcmp(ctype, "x11") == 0) { 1919 c = client_request_x11(ssh, ctype, rchan); 1920 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { 1921 c = client_request_agent(ssh, ctype, rchan); 1922 } 1923 if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { 1924 debug3("proxied to downstream: %s", ctype); 1925 } else if (c != NULL) { 1926 debug("confirm %s", ctype); 1927 c->remote_id = rchan; 1928 c->have_remote_id = 1; 1929 c->remote_window = rwindow; 1930 c->remote_maxpacket = rmaxpack; 1931 if (c->type != SSH_CHANNEL_CONNECTING) { 1932 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 1933 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 1934 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 1935 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 1936 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 1937 (r = sshpkt_send(ssh)) != 0) 1938 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 1939 } 1940 } else { 1941 debug("failure %s", ctype); 1942 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 1943 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 1944 (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 || 1945 (r = sshpkt_put_cstring(ssh, "open failed")) != 0 || 1946 (r = sshpkt_put_cstring(ssh, "")) != 0 || 1947 (r = sshpkt_send(ssh)) != 0) 1948 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 1949 } 1950 r = 0; 1951 out: 1952 free(ctype); 1953 return r; 1954 } 1955 1956 static int 1957 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 1958 { 1959 Channel *c = NULL; 1960 char *rtype = NULL; 1961 u_char reply; 1962 u_int id, exitval; 1963 int r, success = 0; 1964 1965 if ((r = sshpkt_get_u32(ssh, &id)) != 0) 1966 return r; 1967 if (id <= INT_MAX) 1968 c = channel_lookup(ssh, id); 1969 if (channel_proxy_upstream(c, type, seq, ssh)) 1970 return 0; 1971 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 1972 (r = sshpkt_get_u8(ssh, &reply)) != 0) 1973 goto out; 1974 1975 debug("client_input_channel_req: channel %u rtype %s reply %d", 1976 id, rtype, reply); 1977 1978 if (c == NULL) { 1979 error("client_input_channel_req: channel %d: " 1980 "unknown channel", id); 1981 } else if (strcmp(rtype, "eow@openssh.com") == 0) { 1982 if ((r = sshpkt_get_end(ssh)) != 0) 1983 goto out; 1984 chan_rcvd_eow(ssh, c); 1985 } else if (strcmp(rtype, "exit-status") == 0) { 1986 if ((r = sshpkt_get_u32(ssh, &exitval)) != 0) 1987 goto out; 1988 if (c->ctl_chan != -1) { 1989 mux_exit_message(ssh, c, exitval); 1990 success = 1; 1991 } else if ((int)id == session_ident) { 1992 /* Record exit value of local session */ 1993 success = 1; 1994 exit_status = exitval; 1995 } else { 1996 /* Probably for a mux channel that has already closed */ 1997 debug_f("no sink for exit-status on channel %d", 1998 id); 1999 } 2000 if ((r = sshpkt_get_end(ssh)) != 0) 2001 goto out; 2002 } 2003 if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) { 2004 if (!c->have_remote_id) 2005 fatal_f("channel %d: no remote_id", c->self); 2006 if ((r = sshpkt_start(ssh, success ? 2007 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 2008 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 2009 (r = sshpkt_send(ssh)) != 0) 2010 sshpkt_fatal(ssh, r, "%s: send failure", __func__); 2011 } 2012 r = 0; 2013 out: 2014 free(rtype); 2015 return r; 2016 } 2017 2018 struct hostkeys_update_ctx { 2019 /* The hostname and (optionally) IP address string for the server */ 2020 char *host_str, *ip_str; 2021 2022 /* 2023 * Keys received from the server and a flag for each indicating 2024 * whether they already exist in known_hosts. 2025 * keys_match is filled in by hostkeys_find() and later (for new 2026 * keys) by client_global_hostkeys_prove_confirm(). 2027 */ 2028 struct sshkey **keys; 2029 u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */ 2030 int *keys_verified; /* flag for new keys verified by server */ 2031 size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */ 2032 2033 /* 2034 * Keys that are in known_hosts, but were not present in the update 2035 * from the server (i.e. scheduled to be deleted). 2036 * Filled in by hostkeys_find(). 2037 */ 2038 struct sshkey **old_keys; 2039 size_t nold; 2040 2041 /* Various special cases. */ 2042 int complex_hostspec; /* wildcard or manual pattern-list host name */ 2043 int ca_available; /* saw CA key for this host */ 2044 int old_key_seen; /* saw old key with other name/addr */ 2045 int other_name_seen; /* saw key with other name/addr */ 2046 }; 2047 2048 static void 2049 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) 2050 { 2051 size_t i; 2052 2053 if (ctx == NULL) 2054 return; 2055 for (i = 0; i < ctx->nkeys; i++) 2056 sshkey_free(ctx->keys[i]); 2057 free(ctx->keys); 2058 free(ctx->keys_match); 2059 free(ctx->keys_verified); 2060 for (i = 0; i < ctx->nold; i++) 2061 sshkey_free(ctx->old_keys[i]); 2062 free(ctx->old_keys); 2063 free(ctx->host_str); 2064 free(ctx->ip_str); 2065 free(ctx); 2066 } 2067 2068 /* 2069 * Returns non-zero if a known_hosts hostname list is not of a form that 2070 * can be handled by UpdateHostkeys. These include wildcard hostnames and 2071 * hostnames lists that do not follow the form host[,ip]. 2072 */ 2073 static int 2074 hostspec_is_complex(const char *hosts) 2075 { 2076 char *cp; 2077 2078 /* wildcard */ 2079 if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL) 2080 return 1; 2081 /* single host/ip = ok */ 2082 if ((cp = strchr(hosts, ',')) == NULL) 2083 return 0; 2084 /* more than two entries on the line */ 2085 if (strchr(cp + 1, ',') != NULL) 2086 return 1; 2087 /* XXX maybe parse cp+1 and ensure it is an IP? */ 2088 return 0; 2089 } 2090 2091 /* callback to search for ctx->keys in known_hosts */ 2092 static int 2093 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) 2094 { 2095 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2096 size_t i; 2097 struct sshkey **tmp; 2098 2099 if (l->key == NULL) 2100 return 0; 2101 if (l->status != HKF_STATUS_MATCHED) { 2102 /* Record if one of the keys appears on a non-matching line */ 2103 for (i = 0; i < ctx->nkeys; i++) { 2104 if (sshkey_equal(l->key, ctx->keys[i])) { 2105 ctx->other_name_seen = 1; 2106 debug3_f("found %s key under different " 2107 "name/addr at %s:%ld", 2108 sshkey_ssh_name(ctx->keys[i]), 2109 l->path, l->linenum); 2110 return 0; 2111 } 2112 } 2113 return 0; 2114 } 2115 /* Don't proceed if revocation or CA markers are present */ 2116 /* XXX relax this */ 2117 if (l->marker != MRK_NONE) { 2118 debug3_f("hostkeys file %s:%ld has CA/revocation marker", 2119 l->path, l->linenum); 2120 ctx->complex_hostspec = 1; 2121 return 0; 2122 } 2123 2124 /* If CheckHostIP is enabled, then check for mismatched hostname/addr */ 2125 if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) { 2126 if ((l->match & HKF_MATCH_HOST) == 0) { 2127 /* Record if address matched a different hostname. */ 2128 ctx->other_name_seen = 1; 2129 debug3_f("found address %s against different hostname " 2130 "at %s:%ld", ctx->ip_str, l->path, l->linenum); 2131 return 0; 2132 } else if ((l->match & HKF_MATCH_IP) == 0) { 2133 /* Record if hostname matched a different address. */ 2134 ctx->other_name_seen = 1; 2135 debug3_f("found hostname %s against different address " 2136 "at %s:%ld", ctx->host_str, l->path, l->linenum); 2137 } 2138 } 2139 2140 /* 2141 * UpdateHostkeys is skipped for wildcard host names and hostnames 2142 * that contain more than two entries (ssh never writes these). 2143 */ 2144 if (hostspec_is_complex(l->hosts)) { 2145 debug3_f("hostkeys file %s:%ld complex host specification", 2146 l->path, l->linenum); 2147 ctx->complex_hostspec = 1; 2148 return 0; 2149 } 2150 2151 /* Mark off keys we've already seen for this host */ 2152 for (i = 0; i < ctx->nkeys; i++) { 2153 if (!sshkey_equal(l->key, ctx->keys[i])) 2154 continue; 2155 debug3_f("found %s key at %s:%ld", 2156 sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); 2157 ctx->keys_match[i] |= l->match; 2158 return 0; 2159 } 2160 /* This line contained a key that not offered by the server */ 2161 debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key), 2162 l->path, l->linenum); 2163 if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, 2164 sizeof(*ctx->old_keys))) == NULL) 2165 fatal_f("recallocarray failed nold = %zu", ctx->nold); 2166 ctx->old_keys = tmp; 2167 ctx->old_keys[ctx->nold++] = l->key; 2168 l->key = NULL; 2169 2170 return 0; 2171 } 2172 2173 /* callback to search for ctx->old_keys in known_hosts under other names */ 2174 static int 2175 hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx) 2176 { 2177 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2178 size_t i; 2179 int hashed; 2180 2181 /* only care about lines that *don't* match the active host spec */ 2182 if (l->status == HKF_STATUS_MATCHED || l->key == NULL) 2183 return 0; 2184 2185 hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED); 2186 for (i = 0; i < ctx->nold; i++) { 2187 if (!sshkey_equal(l->key, ctx->old_keys[i])) 2188 continue; 2189 debug3_f("found deprecated %s key at %s:%ld as %s", 2190 sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum, 2191 hashed ? "[HASHED]" : l->hosts); 2192 ctx->old_key_seen = 1; 2193 break; 2194 } 2195 return 0; 2196 } 2197 2198 /* 2199 * Check known_hosts files for deprecated keys under other names. Returns 0 2200 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys 2201 * exist under names other than the active hostname/IP. 2202 */ 2203 static int 2204 check_old_keys_othernames(struct hostkeys_update_ctx *ctx) 2205 { 2206 size_t i; 2207 int r; 2208 2209 debug2_f("checking for %zu deprecated keys", ctx->nold); 2210 for (i = 0; i < options.num_user_hostfiles; i++) { 2211 debug3_f("searching %s for %s / %s", 2212 options.user_hostfiles[i], ctx->host_str, 2213 ctx->ip_str ? ctx->ip_str : "(none)"); 2214 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2215 hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str, 2216 HKF_WANT_PARSE_KEY, 0)) != 0) { 2217 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2218 debug_f("hostkeys file %s does not exist", 2219 options.user_hostfiles[i]); 2220 continue; 2221 } 2222 error_fr(r, "hostkeys_foreach failed for %s", 2223 options.user_hostfiles[i]); 2224 return -1; 2225 } 2226 } 2227 return 0; 2228 } 2229 2230 static void 2231 hostkey_change_preamble(LogLevel loglevel) 2232 { 2233 do_log2(loglevel, "The server has updated its host keys."); 2234 do_log2(loglevel, "These changes were verified by the server's " 2235 "existing trusted key."); 2236 } 2237 2238 static void 2239 update_known_hosts(struct hostkeys_update_ctx *ctx) 2240 { 2241 int r, was_raw = 0, first = 1; 2242 int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK; 2243 LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; 2244 char *fp, *response; 2245 size_t i; 2246 struct stat sb; 2247 2248 for (i = 0; i < ctx->nkeys; i++) { 2249 if (!ctx->keys_verified[i]) 2250 continue; 2251 if ((fp = sshkey_fingerprint(ctx->keys[i], 2252 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2253 fatal_f("sshkey_fingerprint failed"); 2254 if (first && asking) 2255 hostkey_change_preamble(loglevel); 2256 do_log2(loglevel, "Learned new hostkey: %s %s", 2257 sshkey_type(ctx->keys[i]), fp); 2258 first = 0; 2259 free(fp); 2260 } 2261 for (i = 0; i < ctx->nold; i++) { 2262 if ((fp = sshkey_fingerprint(ctx->old_keys[i], 2263 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 2264 fatal_f("sshkey_fingerprint failed"); 2265 if (first && asking) 2266 hostkey_change_preamble(loglevel); 2267 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", 2268 sshkey_type(ctx->old_keys[i]), fp); 2269 first = 0; 2270 free(fp); 2271 } 2272 if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { 2273 if (get_saved_tio() != NULL) { 2274 leave_raw_mode(1); 2275 was_raw = 1; 2276 } 2277 response = NULL; 2278 for (i = 0; !quit_pending && i < 3; i++) { 2279 free(response); 2280 response = read_passphrase("Accept updated hostkeys? " 2281 "(yes/no): ", RP_ECHO); 2282 if (response != NULL && strcasecmp(response, "yes") == 0) 2283 break; 2284 else if (quit_pending || response == NULL || 2285 strcasecmp(response, "no") == 0) { 2286 options.update_hostkeys = 0; 2287 break; 2288 } else { 2289 do_log2(loglevel, "Please enter " 2290 "\"yes\" or \"no\""); 2291 } 2292 } 2293 if (quit_pending || i >= 3 || response == NULL) 2294 options.update_hostkeys = 0; 2295 free(response); 2296 if (was_raw) 2297 enter_raw_mode(1); 2298 } 2299 if (options.update_hostkeys == 0) 2300 return; 2301 /* 2302 * Now that all the keys are verified, we can go ahead and replace 2303 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't 2304 * cancel the operation). 2305 */ 2306 for (i = 0; i < options.num_user_hostfiles; i++) { 2307 /* 2308 * NB. keys are only added to hostfiles[0], for the rest we 2309 * just delete the hostname entries. 2310 */ 2311 if (stat(options.user_hostfiles[i], &sb) != 0) { 2312 if (errno == ENOENT) { 2313 debug_f("known hosts file %s does not " 2314 "exist", options.user_hostfiles[i]); 2315 } else { 2316 error_f("known hosts file %s " 2317 "inaccessible: %s", 2318 options.user_hostfiles[i], strerror(errno)); 2319 } 2320 continue; 2321 } 2322 if ((r = hostfile_replace_entries(options.user_hostfiles[i], 2323 ctx->host_str, ctx->ip_str, 2324 i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0, 2325 options.hash_known_hosts, 0, 2326 options.fingerprint_hash)) != 0) { 2327 error_fr(r, "hostfile_replace_entries failed for %s", 2328 options.user_hostfiles[i]); 2329 } 2330 } 2331 } 2332 2333 static void 2334 client_global_hostkeys_prove_confirm(struct ssh *ssh, int type, 2335 u_int32_t seq, void *_ctx) 2336 { 2337 struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; 2338 size_t i, ndone; 2339 struct sshbuf *signdata; 2340 int r, plaintype; 2341 const u_char *sig; 2342 const char *rsa_kexalg = NULL; 2343 char *alg = NULL; 2344 size_t siglen; 2345 2346 if (ctx->nnew == 0) 2347 fatal_f("ctx->nnew == 0"); /* sanity */ 2348 if (type != SSH2_MSG_REQUEST_SUCCESS) { 2349 error("Server failed to confirm ownership of " 2350 "private host keys"); 2351 hostkeys_update_ctx_free(ctx); 2352 return; 2353 } 2354 if (sshkey_type_plain(sshkey_type_from_name( 2355 ssh->kex->hostkey_alg)) == KEY_RSA) 2356 rsa_kexalg = ssh->kex->hostkey_alg; 2357 if ((signdata = sshbuf_new()) == NULL) 2358 fatal_f("sshbuf_new failed"); 2359 /* 2360 * Expect a signature for each of the ctx->nnew private keys we 2361 * haven't seen before. They will be in the same order as the 2362 * ctx->keys where the corresponding ctx->keys_match[i] == 0. 2363 */ 2364 for (ndone = i = 0; i < ctx->nkeys; i++) { 2365 if (ctx->keys_match[i]) 2366 continue; 2367 plaintype = sshkey_type_plain(ctx->keys[i]->type); 2368 /* Prepare data to be signed: session ID, unique string, key */ 2369 sshbuf_reset(signdata); 2370 if ( (r = sshbuf_put_cstring(signdata, 2371 "hostkeys-prove-00@openssh.com")) != 0 || 2372 (r = sshbuf_put_stringb(signdata, 2373 ssh->kex->session_id)) != 0 || 2374 (r = sshkey_puts(ctx->keys[i], signdata)) != 0) 2375 fatal_fr(r, "compose signdata"); 2376 /* Extract and verify signature */ 2377 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { 2378 error_fr(r, "parse sig"); 2379 goto out; 2380 } 2381 if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) { 2382 error_fr(r, "server gave unintelligible signature " 2383 "for %s key %zu", sshkey_type(ctx->keys[i]), i); 2384 goto out; 2385 } 2386 /* 2387 * Special case for RSA keys: if a RSA hostkey was negotiated, 2388 * then use its signature type for verification of RSA hostkey 2389 * proofs. Otherwise, accept only RSA-SHA256/512 signatures. 2390 */ 2391 if (plaintype == KEY_RSA && rsa_kexalg == NULL && 2392 match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) { 2393 debug_f("server used untrusted RSA signature algorithm " 2394 "%s for key %zu, disregarding", alg, i); 2395 free(alg); 2396 /* zap the key from the list */ 2397 sshkey_free(ctx->keys[i]); 2398 ctx->keys[i] = NULL; 2399 ndone++; 2400 continue; 2401 } 2402 debug3_f("verify %s key %zu using sigalg %s", 2403 sshkey_type(ctx->keys[i]), i, alg); 2404 free(alg); 2405 if ((r = sshkey_verify(ctx->keys[i], sig, siglen, 2406 sshbuf_ptr(signdata), sshbuf_len(signdata), 2407 plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) { 2408 error_fr(r, "server gave bad signature for %s key %zu", 2409 sshkey_type(ctx->keys[i]), i); 2410 goto out; 2411 } 2412 /* Key is good. Mark it as 'seen' */ 2413 ctx->keys_verified[i] = 1; 2414 ndone++; 2415 } 2416 /* Shouldn't happen */ 2417 if (ndone != ctx->nnew) 2418 fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew); 2419 if ((r = sshpkt_get_end(ssh)) != 0) { 2420 error_f("protocol error"); 2421 goto out; 2422 } 2423 2424 /* Make the edits to known_hosts */ 2425 update_known_hosts(ctx); 2426 out: 2427 hostkeys_update_ctx_free(ctx); 2428 hostkeys_update_complete = 1; 2429 client_repledge(); 2430 } 2431 2432 /* 2433 * Returns non-zero if the key is accepted by HostkeyAlgorithms. 2434 * Made slightly less trivial by the multiple RSA signature algorithm names. 2435 */ 2436 static int 2437 key_accepted_by_hostkeyalgs(const struct sshkey *key) 2438 { 2439 const char *ktype = sshkey_ssh_name(key); 2440 const char *hostkeyalgs = options.hostkeyalgorithms; 2441 2442 if (key->type == KEY_UNSPEC) 2443 return 0; 2444 if (key->type == KEY_RSA && 2445 (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 || 2446 match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1)) 2447 return 1; 2448 return match_pattern_list(ktype, hostkeyalgs, 0) == 1; 2449 } 2450 2451 /* 2452 * Handle hostkeys-00@openssh.com global request to inform the client of all 2453 * the server's hostkeys. The keys are checked against the user's 2454 * HostkeyAlgorithms preference before they are accepted. 2455 */ 2456 static int 2457 client_input_hostkeys(struct ssh *ssh) 2458 { 2459 const u_char *blob = NULL; 2460 size_t i, len = 0; 2461 struct sshbuf *buf = NULL; 2462 struct sshkey *key = NULL, **tmp; 2463 int r, prove_sent = 0; 2464 char *fp; 2465 static int hostkeys_seen = 0; /* XXX use struct ssh */ 2466 extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ 2467 struct hostkeys_update_ctx *ctx = NULL; 2468 u_int want; 2469 2470 if (hostkeys_seen) 2471 fatal_f("server already sent hostkeys"); 2472 if (!can_update_hostkeys()) 2473 return 1; 2474 hostkeys_seen = 1; 2475 2476 ctx = xcalloc(1, sizeof(*ctx)); 2477 while (ssh_packet_remaining(ssh) > 0) { 2478 sshkey_free(key); 2479 key = NULL; 2480 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { 2481 error_fr(r, "parse key"); 2482 goto out; 2483 } 2484 if ((r = sshkey_from_blob(blob, len, &key)) != 0) { 2485 do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ? 2486 SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR, 2487 "convert key"); 2488 continue; 2489 } 2490 fp = sshkey_fingerprint(key, options.fingerprint_hash, 2491 SSH_FP_DEFAULT); 2492 debug3_f("received %s key %s", sshkey_type(key), fp); 2493 free(fp); 2494 2495 if (!key_accepted_by_hostkeyalgs(key)) { 2496 debug3_f("%s key not permitted by " 2497 "HostkeyAlgorithms", sshkey_ssh_name(key)); 2498 continue; 2499 } 2500 /* Skip certs */ 2501 if (sshkey_is_cert(key)) { 2502 debug3_f("%s key is a certificate; skipping", 2503 sshkey_ssh_name(key)); 2504 continue; 2505 } 2506 /* Ensure keys are unique */ 2507 for (i = 0; i < ctx->nkeys; i++) { 2508 if (sshkey_equal(key, ctx->keys[i])) { 2509 error_f("received duplicated %s host key", 2510 sshkey_ssh_name(key)); 2511 goto out; 2512 } 2513 } 2514 /* Key is good, record it */ 2515 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, 2516 sizeof(*ctx->keys))) == NULL) 2517 fatal_f("recallocarray failed nkeys = %zu", 2518 ctx->nkeys); 2519 ctx->keys = tmp; 2520 ctx->keys[ctx->nkeys++] = key; 2521 key = NULL; 2522 } 2523 2524 if (ctx->nkeys == 0) { 2525 debug_f("server sent no hostkeys"); 2526 goto out; 2527 } 2528 2529 if ((ctx->keys_match = calloc(ctx->nkeys, 2530 sizeof(*ctx->keys_match))) == NULL || 2531 (ctx->keys_verified = calloc(ctx->nkeys, 2532 sizeof(*ctx->keys_verified))) == NULL) 2533 fatal_f("calloc failed"); 2534 2535 get_hostfile_hostname_ipaddr(host, 2536 options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, 2537 options.port, &ctx->host_str, 2538 options.check_host_ip ? &ctx->ip_str : NULL); 2539 2540 /* Find which keys we already know about. */ 2541 for (i = 0; i < options.num_user_hostfiles; i++) { 2542 debug_f("searching %s for %s / %s", 2543 options.user_hostfiles[i], ctx->host_str, 2544 ctx->ip_str ? ctx->ip_str : "(none)"); 2545 if ((r = hostkeys_foreach(options.user_hostfiles[i], 2546 hostkeys_find, ctx, ctx->host_str, ctx->ip_str, 2547 HKF_WANT_PARSE_KEY, 0)) != 0) { 2548 if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { 2549 debug_f("hostkeys file %s does not exist", 2550 options.user_hostfiles[i]); 2551 continue; 2552 } 2553 error_fr(r, "hostkeys_foreach failed for %s", 2554 options.user_hostfiles[i]); 2555 goto out; 2556 } 2557 } 2558 2559 /* Figure out if we have any new keys to add */ 2560 ctx->nnew = ctx->nincomplete = 0; 2561 want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0); 2562 for (i = 0; i < ctx->nkeys; i++) { 2563 if (ctx->keys_match[i] == 0) 2564 ctx->nnew++; 2565 if ((ctx->keys_match[i] & want) != want) 2566 ctx->nincomplete++; 2567 } 2568 2569 debug3_f("%zu server keys: %zu new, %zu retained, " 2570 "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew, 2571 ctx->nkeys - ctx->nnew - ctx->nincomplete, 2572 ctx->nincomplete, ctx->nold); 2573 2574 if (ctx->nnew == 0 && ctx->nold == 0) { 2575 debug_f("no new or deprecated keys from server"); 2576 goto out; 2577 } 2578 2579 /* Various reasons why we cannot proceed with the update */ 2580 if (ctx->complex_hostspec) { 2581 debug_f("CA/revocation marker, manual host list or wildcard " 2582 "host pattern found, skipping UserKnownHostsFile update"); 2583 goto out; 2584 } 2585 if (ctx->other_name_seen) { 2586 debug_f("host key found matching a different name/address, " 2587 "skipping UserKnownHostsFile update"); 2588 goto out; 2589 } 2590 /* 2591 * If removing keys, check whether they appear under different 2592 * names/addresses and refuse to proceed if they do. This avoids 2593 * cases such as hosts with multiple names becoming inconsistent 2594 * with regards to CheckHostIP entries. 2595 * XXX UpdateHostkeys=force to override this (and other) checks? 2596 */ 2597 if (ctx->nold != 0) { 2598 if (check_old_keys_othernames(ctx) != 0) 2599 goto out; /* error already logged */ 2600 if (ctx->old_key_seen) { 2601 debug_f("key(s) for %s%s%s exist under other names; " 2602 "skipping UserKnownHostsFile update", 2603 ctx->host_str, ctx->ip_str == NULL ? "" : ",", 2604 ctx->ip_str == NULL ? "" : ctx->ip_str); 2605 goto out; 2606 } 2607 } 2608 2609 if (ctx->nnew == 0) { 2610 /* 2611 * We have some keys to remove or fix matching for. 2612 * We can proceed to do this without requiring a fresh proof 2613 * from the server. 2614 */ 2615 update_known_hosts(ctx); 2616 goto out; 2617 } 2618 /* 2619 * We have received previously-unseen keys from the server. 2620 * Ask the server to confirm ownership of the private halves. 2621 */ 2622 debug3_f("asking server to prove ownership for %zu keys", ctx->nnew); 2623 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 2624 (r = sshpkt_put_cstring(ssh, 2625 "hostkeys-prove-00@openssh.com")) != 0 || 2626 (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ 2627 fatal_fr(r, "prepare hostkeys-prove"); 2628 if ((buf = sshbuf_new()) == NULL) 2629 fatal_f("sshbuf_new"); 2630 for (i = 0; i < ctx->nkeys; i++) { 2631 if (ctx->keys_match[i]) 2632 continue; 2633 sshbuf_reset(buf); 2634 if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 || 2635 (r = sshpkt_put_stringb(ssh, buf)) != 0) 2636 fatal_fr(r, "assemble hostkeys-prove"); 2637 } 2638 if ((r = sshpkt_send(ssh)) != 0) 2639 fatal_fr(r, "send hostkeys-prove"); 2640 client_register_global_confirm( 2641 client_global_hostkeys_prove_confirm, ctx); 2642 ctx = NULL; /* will be freed in callback */ 2643 prove_sent = 1; 2644 2645 /* Success */ 2646 out: 2647 hostkeys_update_ctx_free(ctx); 2648 sshkey_free(key); 2649 sshbuf_free(buf); 2650 if (!prove_sent) { 2651 /* UpdateHostkeys handling completed */ 2652 hostkeys_update_complete = 1; 2653 client_repledge(); 2654 } 2655 /* 2656 * NB. Return success for all cases. The server doesn't need to know 2657 * what the client does with its hosts file. 2658 */ 2659 return 1; 2660 } 2661 2662 static int 2663 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 2664 { 2665 char *rtype; 2666 u_char want_reply; 2667 int r, success = 0; 2668 2669 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 2670 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 2671 goto out; 2672 debug("client_input_global_request: rtype %s want_reply %d", 2673 rtype, want_reply); 2674 if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) 2675 success = client_input_hostkeys(ssh); 2676 if (want_reply) { 2677 if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : 2678 SSH2_MSG_REQUEST_FAILURE)) != 0 || 2679 (r = sshpkt_send(ssh)) != 0 || 2680 (r = ssh_packet_write_wait(ssh)) != 0) 2681 goto out; 2682 } 2683 r = 0; 2684 out: 2685 free(rtype); 2686 return r; 2687 } 2688 2689 static void 2690 client_send_env(struct ssh *ssh, int id, const char *name, const char *val) 2691 { 2692 int r; 2693 2694 debug("channel %d: setting env %s = \"%s\"", id, name, val); 2695 channel_request_start(ssh, id, "env", 0); 2696 if ((r = sshpkt_put_cstring(ssh, name)) != 0 || 2697 (r = sshpkt_put_cstring(ssh, val)) != 0 || 2698 (r = sshpkt_send(ssh)) != 0) 2699 fatal_fr(r, "send setenv"); 2700 } 2701 2702 void 2703 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, 2704 const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd, 2705 char **env) 2706 { 2707 size_t i, j, len; 2708 int matched, r; 2709 char *name, *val; 2710 Channel *c = NULL; 2711 2712 debug2_f("id %d", id); 2713 2714 if ((c = channel_lookup(ssh, id)) == NULL) 2715 fatal_f("channel %d: unknown channel", id); 2716 2717 ssh_packet_set_interactive(ssh, want_tty, 2718 options.ip_qos_interactive, options.ip_qos_bulk); 2719 2720 if (want_tty) { 2721 struct winsize ws; 2722 2723 /* Store window size in the packet. */ 2724 if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1) 2725 memset(&ws, 0, sizeof(ws)); 2726 2727 channel_request_start(ssh, id, "pty-req", 1); 2728 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); 2729 if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : "")) 2730 != 0 || 2731 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || 2732 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || 2733 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || 2734 (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0) 2735 fatal_fr(r, "build pty-req"); 2736 if (tiop == NULL) 2737 tiop = get_saved_tio(); 2738 ssh_tty_make_modes(ssh, -1, tiop); 2739 if ((r = sshpkt_send(ssh)) != 0) 2740 fatal_fr(r, "send pty-req"); 2741 /* XXX wait for reply */ 2742 c->client_tty = 1; 2743 } 2744 2745 /* Transfer any environment variables from client to server */ 2746 if (options.num_send_env != 0 && env != NULL) { 2747 debug("Sending environment."); 2748 for (i = 0; env[i] != NULL; i++) { 2749 /* Split */ 2750 name = xstrdup(env[i]); 2751 if ((val = strchr(name, '=')) == NULL) { 2752 free(name); 2753 continue; 2754 } 2755 *val++ = '\0'; 2756 2757 matched = 0; 2758 for (j = 0; j < options.num_send_env; j++) { 2759 if (match_pattern(name, options.send_env[j])) { 2760 matched = 1; 2761 break; 2762 } 2763 } 2764 if (!matched) { 2765 debug3("Ignored env %s", name); 2766 free(name); 2767 continue; 2768 } 2769 client_send_env(ssh, id, name, val); 2770 free(name); 2771 } 2772 } 2773 for (i = 0; i < options.num_setenv; i++) { 2774 /* Split */ 2775 name = xstrdup(options.setenv[i]); 2776 if ((val = strchr(name, '=')) == NULL) { 2777 free(name); 2778 continue; 2779 } 2780 *val++ = '\0'; 2781 client_send_env(ssh, id, name, val); 2782 free(name); 2783 } 2784 2785 len = sshbuf_len(cmd); 2786 if (len > 0) { 2787 if (len > 900) 2788 len = 900; 2789 if (want_subsystem) { 2790 debug("Sending subsystem: %.*s", 2791 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2792 channel_request_start(ssh, id, "subsystem", 1); 2793 client_expect_confirm(ssh, id, "subsystem", 2794 CONFIRM_CLOSE); 2795 } else { 2796 debug("Sending command: %.*s", 2797 (int)len, (const u_char*)sshbuf_ptr(cmd)); 2798 channel_request_start(ssh, id, "exec", 1); 2799 client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); 2800 } 2801 if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 || 2802 (r = sshpkt_send(ssh)) != 0) 2803 fatal_fr(r, "send command"); 2804 } else { 2805 channel_request_start(ssh, id, "shell", 1); 2806 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); 2807 if ((r = sshpkt_send(ssh)) != 0) 2808 fatal_fr(r, "send shell"); 2809 } 2810 2811 session_setup_complete = 1; 2812 client_repledge(); 2813 } 2814 2815 static void 2816 client_init_dispatch(struct ssh *ssh) 2817 { 2818 ssh_dispatch_init(ssh, &dispatch_protocol_error); 2819 2820 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 2821 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 2822 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 2823 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 2824 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open); 2825 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 2826 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 2827 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req); 2828 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 2829 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); 2830 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); 2831 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); 2832 2833 /* rekeying */ 2834 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 2835 2836 /* global request reply messages */ 2837 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); 2838 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); 2839 } 2840 2841 void 2842 client_stop_mux(void) 2843 { 2844 if (options.control_path != NULL && muxserver_sock != -1) 2845 unlink(options.control_path); 2846 /* 2847 * If we are in persist mode, or don't have a shell, signal that we 2848 * should close when all active channels are closed. 2849 */ 2850 if (options.control_persist || options.session_type == SESSION_TYPE_NONE) { 2851 session_closed = 1; 2852 setproctitle("[stopped mux]"); 2853 } 2854 } 2855 2856 /* client specific fatal cleanup */ 2857 void 2858 cleanup_exit(int i) 2859 { 2860 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2861 if (options.control_path != NULL && muxserver_sock != -1) 2862 unlink(options.control_path); 2863 ssh_kill_proxy_command(); 2864 _exit(i); 2865 } 2866