1 /* $OpenBSD: sshconnect.c,v 1.259 2015/01/28 22:36:00 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 * Code to connect to a remote host, and to perform the client side of the 7 * login (authentication) dialog. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 */ 15 16 #include "includes.h" 17 __RCSID("$FreeBSD$"); 18 19 #include <sys/param.h> /* roundup */ 20 #include <sys/types.h> 21 #include <sys/wait.h> 22 #include <sys/stat.h> 23 #include <sys/socket.h> 24 #ifdef HAVE_SYS_TIME_H 25 # include <sys/time.h> 26 #endif 27 28 #include <netinet/in.h> 29 #include <arpa/inet.h> 30 #include <rpc/rpc.h> 31 32 #include <ctype.h> 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #ifdef HAVE_PATHS_H 37 #include <paths.h> 38 #endif 39 #include <pwd.h> 40 #include <signal.h> 41 #include <stdarg.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <unistd.h> 46 47 #include "xmalloc.h" 48 #include "key.h" 49 #include "hostfile.h" 50 #include "ssh.h" 51 #include "rsa.h" 52 #include "buffer.h" 53 #include "packet.h" 54 #include "uidswap.h" 55 #include "compat.h" 56 #include "key.h" 57 #include "sshconnect.h" 58 #include "hostfile.h" 59 #include "log.h" 60 #include "misc.h" 61 #include "readconf.h" 62 #include "atomicio.h" 63 #include "dns.h" 64 #include "roaming.h" 65 #include "monitor_fdpass.h" 66 #include "ssh2.h" 67 #include "version.h" 68 #include "authfile.h" 69 #include "ssherr.h" 70 71 char *client_version_string = NULL; 72 char *server_version_string = NULL; 73 Key *previous_host_key = NULL; 74 75 static int matching_host_key_dns = 0; 76 77 static pid_t proxy_command_pid = 0; 78 79 /* import */ 80 extern Options options; 81 extern char *__progname; 82 extern uid_t original_real_uid; 83 extern uid_t original_effective_uid; 84 85 static int show_other_keys(struct hostkeys *, Key *); 86 static void warn_changed_key(Key *); 87 88 /* Expand a proxy command */ 89 static char * 90 expand_proxy_command(const char *proxy_command, const char *user, 91 const char *host, int port) 92 { 93 char *tmp, *ret, strport[NI_MAXSERV]; 94 95 snprintf(strport, sizeof strport, "%d", port); 96 xasprintf(&tmp, "exec %s", proxy_command); 97 ret = percent_expand(tmp, "h", host, "p", strport, 98 "r", options.user, (char *)NULL); 99 free(tmp); 100 return ret; 101 } 102 103 /* 104 * Connect to the given ssh server using a proxy command that passes a 105 * a connected fd back to us. 106 */ 107 static int 108 ssh_proxy_fdpass_connect(const char *host, u_short port, 109 const char *proxy_command) 110 { 111 char *command_string; 112 int sp[2], sock; 113 pid_t pid; 114 char *shell; 115 116 if ((shell = getenv("SHELL")) == NULL) 117 shell = _PATH_BSHELL; 118 119 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 120 fatal("Could not create socketpair to communicate with " 121 "proxy dialer: %.100s", strerror(errno)); 122 123 command_string = expand_proxy_command(proxy_command, options.user, 124 host, port); 125 debug("Executing proxy dialer command: %.500s", command_string); 126 127 /* Fork and execute the proxy command. */ 128 if ((pid = fork()) == 0) { 129 char *argv[10]; 130 131 /* Child. Permanently give up superuser privileges. */ 132 permanently_drop_suid(original_real_uid); 133 134 close(sp[1]); 135 /* Redirect stdin and stdout. */ 136 if (sp[0] != 0) { 137 if (dup2(sp[0], 0) < 0) 138 perror("dup2 stdin"); 139 } 140 if (sp[0] != 1) { 141 if (dup2(sp[0], 1) < 0) 142 perror("dup2 stdout"); 143 } 144 if (sp[0] >= 2) 145 close(sp[0]); 146 147 /* 148 * Stderr is left as it is so that error messages get 149 * printed on the user's terminal. 150 */ 151 argv[0] = shell; 152 argv[1] = "-c"; 153 argv[2] = command_string; 154 argv[3] = NULL; 155 156 /* 157 * Execute the proxy command. 158 * Note that we gave up any extra privileges above. 159 */ 160 execv(argv[0], argv); 161 perror(argv[0]); 162 exit(1); 163 } 164 /* Parent. */ 165 if (pid < 0) 166 fatal("fork failed: %.100s", strerror(errno)); 167 close(sp[0]); 168 free(command_string); 169 170 if ((sock = mm_receive_fd(sp[1])) == -1) 171 fatal("proxy dialer did not pass back a connection"); 172 173 while (waitpid(pid, NULL, 0) == -1) 174 if (errno != EINTR) 175 fatal("Couldn't wait for child: %s", strerror(errno)); 176 177 /* Set the connection file descriptors. */ 178 packet_set_connection(sock, sock); 179 180 return 0; 181 } 182 183 /* 184 * Connect to the given ssh server using a proxy command. 185 */ 186 static int 187 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 188 { 189 char *command_string; 190 int pin[2], pout[2]; 191 pid_t pid; 192 char *shell; 193 194 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 195 shell = _PATH_BSHELL; 196 197 /* Create pipes for communicating with the proxy. */ 198 if (pipe(pin) < 0 || pipe(pout) < 0) 199 fatal("Could not create pipes to communicate with the proxy: %.100s", 200 strerror(errno)); 201 202 command_string = expand_proxy_command(proxy_command, options.user, 203 host, port); 204 debug("Executing proxy command: %.500s", command_string); 205 206 /* Fork and execute the proxy command. */ 207 if ((pid = fork()) == 0) { 208 char *argv[10]; 209 210 /* Child. Permanently give up superuser privileges. */ 211 permanently_drop_suid(original_real_uid); 212 213 /* Redirect stdin and stdout. */ 214 close(pin[1]); 215 if (pin[0] != 0) { 216 if (dup2(pin[0], 0) < 0) 217 perror("dup2 stdin"); 218 close(pin[0]); 219 } 220 close(pout[0]); 221 if (dup2(pout[1], 1) < 0) 222 perror("dup2 stdout"); 223 /* Cannot be 1 because pin allocated two descriptors. */ 224 close(pout[1]); 225 226 /* Stderr is left as it is so that error messages get 227 printed on the user's terminal. */ 228 argv[0] = shell; 229 argv[1] = "-c"; 230 argv[2] = command_string; 231 argv[3] = NULL; 232 233 /* Execute the proxy command. Note that we gave up any 234 extra privileges above. */ 235 signal(SIGPIPE, SIG_DFL); 236 execv(argv[0], argv); 237 perror(argv[0]); 238 exit(1); 239 } 240 /* Parent. */ 241 if (pid < 0) 242 fatal("fork failed: %.100s", strerror(errno)); 243 else 244 proxy_command_pid = pid; /* save pid to clean up later */ 245 246 /* Close child side of the descriptors. */ 247 close(pin[0]); 248 close(pout[1]); 249 250 /* Free the command name. */ 251 free(command_string); 252 253 /* Set the connection file descriptors. */ 254 packet_set_connection(pout[0], pin[1]); 255 256 /* Indicate OK return */ 257 return 0; 258 } 259 260 void 261 ssh_kill_proxy_command(void) 262 { 263 /* 264 * Send SIGHUP to proxy command if used. We don't wait() in 265 * case it hangs and instead rely on init to reap the child 266 */ 267 if (proxy_command_pid > 1) 268 kill(proxy_command_pid, SIGHUP); 269 } 270 271 /* 272 * Creates a (possibly privileged) socket for use as the ssh connection. 273 */ 274 static int 275 ssh_create_socket(int privileged, struct addrinfo *ai) 276 { 277 int sock, r, gaierr; 278 struct addrinfo hints, *res = NULL; 279 280 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 281 if (sock < 0) { 282 error("socket: %s", strerror(errno)); 283 return -1; 284 } 285 fcntl(sock, F_SETFD, FD_CLOEXEC); 286 287 /* Bind the socket to an alternative local IP address */ 288 if (options.bind_address == NULL && !privileged) 289 return sock; 290 291 if (options.bind_address) { 292 memset(&hints, 0, sizeof(hints)); 293 hints.ai_family = ai->ai_family; 294 hints.ai_socktype = ai->ai_socktype; 295 hints.ai_protocol = ai->ai_protocol; 296 hints.ai_flags = AI_PASSIVE; 297 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 298 if (gaierr) { 299 error("getaddrinfo: %s: %s", options.bind_address, 300 ssh_gai_strerror(gaierr)); 301 close(sock); 302 return -1; 303 } 304 } 305 /* 306 * If we are running as root and want to connect to a privileged 307 * port, bind our own socket to a privileged port. 308 */ 309 if (privileged) { 310 PRIV_START; 311 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 312 PRIV_END; 313 if (r < 0) { 314 error("bindresvport_sa: af=%d %s", ai->ai_family, 315 strerror(errno)); 316 goto fail; 317 } 318 } else { 319 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 320 error("bind: %s: %s", options.bind_address, 321 strerror(errno)); 322 fail: 323 close(sock); 324 freeaddrinfo(res); 325 return -1; 326 } 327 } 328 if (res != NULL) 329 freeaddrinfo(res); 330 return sock; 331 } 332 333 static int 334 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 335 socklen_t addrlen, int *timeoutp) 336 { 337 fd_set *fdset; 338 struct timeval tv, t_start; 339 socklen_t optlen; 340 int optval, rc, result = -1; 341 342 gettimeofday(&t_start, NULL); 343 344 if (*timeoutp <= 0) { 345 result = connect(sockfd, serv_addr, addrlen); 346 goto done; 347 } 348 349 set_nonblock(sockfd); 350 rc = connect(sockfd, serv_addr, addrlen); 351 if (rc == 0) { 352 unset_nonblock(sockfd); 353 result = 0; 354 goto done; 355 } 356 if (errno != EINPROGRESS) { 357 result = -1; 358 goto done; 359 } 360 361 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), 362 sizeof(fd_mask)); 363 FD_SET(sockfd, fdset); 364 ms_to_timeval(&tv, *timeoutp); 365 366 for (;;) { 367 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 368 if (rc != -1 || errno != EINTR) 369 break; 370 } 371 372 switch (rc) { 373 case 0: 374 /* Timed out */ 375 errno = ETIMEDOUT; 376 break; 377 case -1: 378 /* Select error */ 379 debug("select: %s", strerror(errno)); 380 break; 381 case 1: 382 /* Completed or failed */ 383 optval = 0; 384 optlen = sizeof(optval); 385 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 386 &optlen) == -1) { 387 debug("getsockopt: %s", strerror(errno)); 388 break; 389 } 390 if (optval != 0) { 391 errno = optval; 392 break; 393 } 394 result = 0; 395 unset_nonblock(sockfd); 396 break; 397 default: 398 /* Should not occur */ 399 fatal("Bogus return (%d) from select()", rc); 400 } 401 402 free(fdset); 403 404 done: 405 if (result == 0 && *timeoutp > 0) { 406 ms_subtract_diff(&t_start, timeoutp); 407 if (*timeoutp <= 0) { 408 errno = ETIMEDOUT; 409 result = -1; 410 } 411 } 412 413 return (result); 414 } 415 416 /* 417 * Opens a TCP/IP connection to the remote server on the given host. 418 * The address of the remote host will be returned in hostaddr. 419 * If port is 0, the default port will be used. If needpriv is true, 420 * a privileged port will be allocated to make the connection. 421 * This requires super-user privileges if needpriv is true. 422 * Connection_attempts specifies the maximum number of tries (one per 423 * second). If proxy_command is non-NULL, it specifies the command (with %h 424 * and %p substituted for host and port, respectively) to use to contact 425 * the daemon. 426 */ 427 static int 428 ssh_connect_direct(const char *host, struct addrinfo *aitop, 429 struct sockaddr_storage *hostaddr, u_short port, int family, 430 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 431 { 432 int on = 1; 433 int sock = -1, attempt; 434 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 435 struct addrinfo *ai; 436 437 debug2("ssh_connect: needpriv %d", needpriv); 438 439 for (attempt = 0; attempt < connection_attempts; attempt++) { 440 if (attempt > 0) { 441 /* Sleep a moment before retrying. */ 442 sleep(1); 443 debug("Trying again..."); 444 } 445 /* 446 * Loop through addresses for this host, and try each one in 447 * sequence until the connection succeeds. 448 */ 449 for (ai = aitop; ai; ai = ai->ai_next) { 450 if (ai->ai_family != AF_INET && 451 ai->ai_family != AF_INET6) 452 continue; 453 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 454 ntop, sizeof(ntop), strport, sizeof(strport), 455 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 456 error("ssh_connect: getnameinfo failed"); 457 continue; 458 } 459 debug("Connecting to %.200s [%.100s] port %s.", 460 host, ntop, strport); 461 462 /* Create a socket for connecting. */ 463 sock = ssh_create_socket(needpriv, ai); 464 if (sock < 0) 465 /* Any error is already output */ 466 continue; 467 468 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 469 timeout_ms) >= 0) { 470 /* Successful connection. */ 471 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 472 break; 473 } else { 474 debug("connect to address %s port %s: %s", 475 ntop, strport, strerror(errno)); 476 close(sock); 477 sock = -1; 478 } 479 } 480 if (sock != -1) 481 break; /* Successful connection. */ 482 } 483 484 /* Return failure if we didn't get a successful connection. */ 485 if (sock == -1) { 486 error("ssh: connect to host %s port %s: %s", 487 host, strport, strerror(errno)); 488 return (-1); 489 } 490 491 debug("Connection established."); 492 493 /* Set SO_KEEPALIVE if requested. */ 494 if (want_keepalive && 495 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 496 sizeof(on)) < 0) 497 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 498 499 /* Set the connection. */ 500 packet_set_connection(sock, sock); 501 502 return 0; 503 } 504 505 int 506 ssh_connect(const char *host, struct addrinfo *addrs, 507 struct sockaddr_storage *hostaddr, u_short port, int family, 508 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 509 { 510 if (options.proxy_command == NULL) { 511 return ssh_connect_direct(host, addrs, hostaddr, port, family, 512 connection_attempts, timeout_ms, want_keepalive, needpriv); 513 } else if (strcmp(options.proxy_command, "-") == 0) { 514 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 515 return 0; /* Always succeeds */ 516 } else if (options.proxy_use_fdpass) { 517 return ssh_proxy_fdpass_connect(host, port, 518 options.proxy_command); 519 } 520 return ssh_proxy_connect(host, port, options.proxy_command); 521 } 522 523 static void 524 send_client_banner(int connection_out, int minor1) 525 { 526 /* Send our own protocol version identification. */ 527 xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s%s", 528 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 529 compat20 ? PROTOCOL_MINOR_2 : minor1, 530 SSH_VERSION, 531 *options.version_addendum == '\0' ? "" : " ", 532 options.version_addendum, compat20 ? "\r\n" : "\n"); 533 if (roaming_atomicio(vwrite, connection_out, client_version_string, 534 strlen(client_version_string)) != strlen(client_version_string)) 535 fatal("write: %.100s", strerror(errno)); 536 chop(client_version_string); 537 debug("Local version string %.100s", client_version_string); 538 } 539 540 /* 541 * Waits for the server identification string, and sends our own 542 * identification string. 543 */ 544 void 545 ssh_exchange_identification(int timeout_ms) 546 { 547 char buf[256], remote_version[256]; /* must be same size! */ 548 int remote_major, remote_minor, mismatch; 549 int connection_in = packet_get_connection_in(); 550 int connection_out = packet_get_connection_out(); 551 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 552 u_int i, n; 553 size_t len; 554 int fdsetsz, remaining, rc; 555 struct timeval t_start, t_remaining; 556 fd_set *fdset; 557 558 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 559 fdset = xcalloc(1, fdsetsz); 560 561 /* 562 * If we are SSH2-only then we can send the banner immediately and 563 * save a round-trip. 564 */ 565 if (options.protocol == SSH_PROTO_2) { 566 enable_compat20(); 567 send_client_banner(connection_out, 0); 568 client_banner_sent = 1; 569 } 570 571 /* Read other side's version identification. */ 572 remaining = timeout_ms; 573 for (n = 0;;) { 574 for (i = 0; i < sizeof(buf) - 1; i++) { 575 if (timeout_ms > 0) { 576 gettimeofday(&t_start, NULL); 577 ms_to_timeval(&t_remaining, remaining); 578 FD_SET(connection_in, fdset); 579 rc = select(connection_in + 1, fdset, NULL, 580 fdset, &t_remaining); 581 ms_subtract_diff(&t_start, &remaining); 582 if (rc == 0 || remaining <= 0) 583 fatal("Connection timed out during " 584 "banner exchange"); 585 if (rc == -1) { 586 if (errno == EINTR) 587 continue; 588 fatal("ssh_exchange_identification: " 589 "select: %s", strerror(errno)); 590 } 591 } 592 593 len = roaming_atomicio(read, connection_in, &buf[i], 1); 594 595 if (len != 1 && errno == EPIPE) 596 fatal("ssh_exchange_identification: " 597 "Connection closed by remote host"); 598 else if (len != 1) 599 fatal("ssh_exchange_identification: " 600 "read: %.100s", strerror(errno)); 601 if (buf[i] == '\r') { 602 buf[i] = '\n'; 603 buf[i + 1] = 0; 604 continue; /**XXX wait for \n */ 605 } 606 if (buf[i] == '\n') { 607 buf[i + 1] = 0; 608 break; 609 } 610 if (++n > 65536) 611 fatal("ssh_exchange_identification: " 612 "No banner received"); 613 } 614 buf[sizeof(buf) - 1] = 0; 615 if (strncmp(buf, "SSH-", 4) == 0) 616 break; 617 debug("ssh_exchange_identification: %s", buf); 618 } 619 server_version_string = xstrdup(buf); 620 free(fdset); 621 622 /* 623 * Check that the versions match. In future this might accept 624 * several versions and set appropriate flags to handle them. 625 */ 626 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 627 &remote_major, &remote_minor, remote_version) != 3) 628 fatal("Bad remote protocol version identification: '%.100s'", buf); 629 debug("Remote protocol version %d.%d, remote software version %.100s", 630 remote_major, remote_minor, remote_version); 631 632 active_state->compat = compat_datafellows(remote_version); 633 mismatch = 0; 634 635 switch (remote_major) { 636 case 1: 637 if (remote_minor == 99 && 638 (options.protocol & SSH_PROTO_2) && 639 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 640 enable_compat20(); 641 break; 642 } 643 if (!(options.protocol & SSH_PROTO_1)) { 644 mismatch = 1; 645 break; 646 } 647 if (remote_minor < 3) { 648 fatal("Remote machine has too old SSH software version."); 649 } else if (remote_minor == 3 || remote_minor == 4) { 650 /* We speak 1.3, too. */ 651 enable_compat13(); 652 minor1 = 3; 653 if (options.forward_agent) { 654 logit("Agent forwarding disabled for protocol 1.3"); 655 options.forward_agent = 0; 656 } 657 } 658 break; 659 case 2: 660 if (options.protocol & SSH_PROTO_2) { 661 enable_compat20(); 662 break; 663 } 664 /* FALLTHROUGH */ 665 default: 666 mismatch = 1; 667 break; 668 } 669 if (mismatch) 670 fatal("Protocol major versions differ: %d vs. %d", 671 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 672 remote_major); 673 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 674 fatal("Server version \"%.100s\" uses unsafe key agreement; " 675 "refusing connection", remote_version); 676 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 677 logit("Server version \"%.100s\" uses unsafe RSA signature " 678 "scheme; disabling use of RSA keys", remote_version); 679 if (!client_banner_sent) 680 send_client_banner(connection_out, minor1); 681 chop(server_version_string); 682 } 683 684 /* defaults to 'no' */ 685 static int 686 confirm(const char *prompt) 687 { 688 const char *msg, *again = "Please type 'yes' or 'no': "; 689 char *p; 690 int ret = -1; 691 692 if (options.batch_mode) 693 return 0; 694 for (msg = prompt;;msg = again) { 695 p = read_passphrase(msg, RP_ECHO); 696 if (p == NULL || 697 (p[0] == '\0') || (p[0] == '\n') || 698 strncasecmp(p, "no", 2) == 0) 699 ret = 0; 700 if (p && strncasecmp(p, "yes", 3) == 0) 701 ret = 1; 702 free(p); 703 if (ret != -1) 704 return ret; 705 } 706 } 707 708 static int 709 check_host_cert(const char *host, const Key *host_key) 710 { 711 const char *reason; 712 713 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 714 error("%s", reason); 715 return 0; 716 } 717 if (buffer_len(host_key->cert->critical) != 0) { 718 error("Certificate for %s contains unsupported " 719 "critical options(s)", host); 720 return 0; 721 } 722 return 1; 723 } 724 725 static int 726 sockaddr_is_local(struct sockaddr *hostaddr) 727 { 728 switch (hostaddr->sa_family) { 729 case AF_INET: 730 return (ntohl(((struct sockaddr_in *)hostaddr)-> 731 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 732 case AF_INET6: 733 return IN6_IS_ADDR_LOOPBACK( 734 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 735 default: 736 return 0; 737 } 738 } 739 740 /* 741 * Prepare the hostname and ip address strings that are used to lookup 742 * host keys in known_hosts files. These may have a port number appended. 743 */ 744 void 745 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 746 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 747 { 748 char ntop[NI_MAXHOST]; 749 socklen_t addrlen; 750 751 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 752 case -1: 753 addrlen = 0; 754 break; 755 case AF_INET: 756 addrlen = sizeof(struct sockaddr_in); 757 break; 758 case AF_INET6: 759 addrlen = sizeof(struct sockaddr_in6); 760 break; 761 default: 762 addrlen = sizeof(struct sockaddr); 763 break; 764 } 765 766 /* 767 * We don't have the remote ip-address for connections 768 * using a proxy command 769 */ 770 if (hostfile_ipaddr != NULL) { 771 if (options.proxy_command == NULL) { 772 if (getnameinfo(hostaddr, addrlen, 773 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 774 fatal("%s: getnameinfo failed", __func__); 775 *hostfile_ipaddr = put_host_port(ntop, port); 776 } else { 777 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 778 "command>"); 779 } 780 } 781 782 /* 783 * Allow the user to record the key under a different name or 784 * differentiate a non-standard port. This is useful for ssh 785 * tunneling over forwarded connections or if you run multiple 786 * sshd's on different ports on the same machine. 787 */ 788 if (hostfile_hostname != NULL) { 789 if (options.host_key_alias != NULL) { 790 *hostfile_hostname = xstrdup(options.host_key_alias); 791 debug("using hostkeyalias: %s", *hostfile_hostname); 792 } else { 793 *hostfile_hostname = put_host_port(hostname, port); 794 } 795 } 796 } 797 798 /* 799 * check whether the supplied host key is valid, return -1 if the key 800 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 801 */ 802 #define RDRW 0 803 #define RDONLY 1 804 #define ROQUIET 2 805 static int 806 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 807 Key *host_key, int readonly, 808 char **user_hostfiles, u_int num_user_hostfiles, 809 char **system_hostfiles, u_int num_system_hostfiles) 810 { 811 HostStatus host_status; 812 HostStatus ip_status; 813 Key *raw_key = NULL; 814 char *ip = NULL, *host = NULL; 815 char hostline[1000], *hostp, *fp, *ra; 816 char msg[1024]; 817 const char *type; 818 const struct hostkey_entry *host_found, *ip_found; 819 int len, cancelled_forwarding = 0; 820 int local = sockaddr_is_local(hostaddr); 821 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 822 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 823 struct hostkeys *host_hostkeys, *ip_hostkeys; 824 u_int i; 825 826 /* 827 * Force accepting of the host key for loopback/localhost. The 828 * problem is that if the home directory is NFS-mounted to multiple 829 * machines, localhost will refer to a different machine in each of 830 * them, and the user will get bogus HOST_CHANGED warnings. This 831 * essentially disables host authentication for localhost; however, 832 * this is probably not a real problem. 833 */ 834 if (options.no_host_authentication_for_localhost == 1 && local && 835 options.host_key_alias == NULL) { 836 debug("Forcing accepting of host key for " 837 "loopback/localhost."); 838 return 0; 839 } 840 841 /* 842 * Prepare the hostname and address strings used for hostkey lookup. 843 * In some cases, these will have a port number appended. 844 */ 845 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 846 847 /* 848 * Turn off check_host_ip if the connection is to localhost, via proxy 849 * command or if we don't have a hostname to compare with 850 */ 851 if (options.check_host_ip && (local || 852 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 853 options.check_host_ip = 0; 854 855 host_hostkeys = init_hostkeys(); 856 for (i = 0; i < num_user_hostfiles; i++) 857 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 858 for (i = 0; i < num_system_hostfiles; i++) 859 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 860 861 ip_hostkeys = NULL; 862 if (!want_cert && options.check_host_ip) { 863 ip_hostkeys = init_hostkeys(); 864 for (i = 0; i < num_user_hostfiles; i++) 865 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 866 for (i = 0; i < num_system_hostfiles; i++) 867 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 868 } 869 870 retry: 871 /* Reload these as they may have changed on cert->key downgrade */ 872 want_cert = key_is_cert(host_key); 873 type = key_type(host_key); 874 875 /* 876 * Check if the host key is present in the user's list of known 877 * hosts or in the systemwide list. 878 */ 879 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 880 &host_found); 881 882 /* 883 * Also perform check for the ip address, skip the check if we are 884 * localhost, looking for a certificate, or the hostname was an ip 885 * address to begin with. 886 */ 887 if (!want_cert && ip_hostkeys != NULL) { 888 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 889 &ip_found); 890 if (host_status == HOST_CHANGED && 891 (ip_status != HOST_CHANGED || 892 (ip_found != NULL && 893 !key_equal(ip_found->key, host_found->key)))) 894 host_ip_differ = 1; 895 } else 896 ip_status = host_status; 897 898 switch (host_status) { 899 case HOST_OK: 900 /* The host is known and the key matches. */ 901 debug("Host '%.200s' is known and matches the %s host %s.", 902 host, type, want_cert ? "certificate" : "key"); 903 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 904 host_found->file, host_found->line); 905 if (want_cert && !check_host_cert(hostname, host_key)) 906 goto fail; 907 if (options.check_host_ip && ip_status == HOST_NEW) { 908 if (readonly || want_cert) 909 logit("%s host key for IP address " 910 "'%.128s' not in list of known hosts.", 911 type, ip); 912 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 913 host_key, options.hash_known_hosts)) 914 logit("Failed to add the %s host key for IP " 915 "address '%.128s' to the list of known " 916 "hosts (%.30s).", type, ip, 917 user_hostfiles[0]); 918 else 919 logit("Warning: Permanently added the %s host " 920 "key for IP address '%.128s' to the list " 921 "of known hosts.", type, ip); 922 } else if (options.visual_host_key) { 923 fp = sshkey_fingerprint(host_key, 924 options.fingerprint_hash, SSH_FP_DEFAULT); 925 ra = sshkey_fingerprint(host_key, 926 options.fingerprint_hash, SSH_FP_RANDOMART); 927 if (fp == NULL || ra == NULL) 928 fatal("%s: sshkey_fingerprint fail", __func__); 929 logit("Host key fingerprint is %s\n%s\n", fp, ra); 930 free(ra); 931 free(fp); 932 } 933 hostkey_trusted = 1; 934 break; 935 case HOST_NEW: 936 if (options.host_key_alias == NULL && port != 0 && 937 port != SSH_DEFAULT_PORT) { 938 debug("checking without port identifier"); 939 if (check_host_key(hostname, hostaddr, 0, host_key, 940 ROQUIET, user_hostfiles, num_user_hostfiles, 941 system_hostfiles, num_system_hostfiles) == 0) { 942 debug("found matching key w/out port"); 943 break; 944 } 945 } 946 if (readonly || want_cert) 947 goto fail; 948 /* The host is new. */ 949 if (options.strict_host_key_checking == 1) { 950 /* 951 * User has requested strict host key checking. We 952 * will not add the host key automatically. The only 953 * alternative left is to abort. 954 */ 955 error("No %s host key is known for %.200s and you " 956 "have requested strict checking.", type, host); 957 goto fail; 958 } else if (options.strict_host_key_checking == 2) { 959 char msg1[1024], msg2[1024]; 960 961 if (show_other_keys(host_hostkeys, host_key)) 962 snprintf(msg1, sizeof(msg1), 963 "\nbut keys of different type are already" 964 " known for this host."); 965 else 966 snprintf(msg1, sizeof(msg1), "."); 967 /* The default */ 968 fp = sshkey_fingerprint(host_key, 969 options.fingerprint_hash, SSH_FP_DEFAULT); 970 ra = sshkey_fingerprint(host_key, 971 options.fingerprint_hash, SSH_FP_RANDOMART); 972 if (fp == NULL || ra == NULL) 973 fatal("%s: sshkey_fingerprint fail", __func__); 974 msg2[0] = '\0'; 975 if (options.verify_host_key_dns) { 976 if (matching_host_key_dns) 977 snprintf(msg2, sizeof(msg2), 978 "Matching host key fingerprint" 979 " found in DNS.\n"); 980 else 981 snprintf(msg2, sizeof(msg2), 982 "No matching host key fingerprint" 983 " found in DNS.\n"); 984 } 985 snprintf(msg, sizeof(msg), 986 "The authenticity of host '%.200s (%s)' can't be " 987 "established%s\n" 988 "%s key fingerprint is %s.%s%s\n%s" 989 "Are you sure you want to continue connecting " 990 "(yes/no)? ", 991 host, ip, msg1, type, fp, 992 options.visual_host_key ? "\n" : "", 993 options.visual_host_key ? ra : "", 994 msg2); 995 free(ra); 996 free(fp); 997 if (!confirm(msg)) 998 goto fail; 999 hostkey_trusted = 1; /* user explicitly confirmed */ 1000 } 1001 /* 1002 * If not in strict mode, add the key automatically to the 1003 * local known_hosts file. 1004 */ 1005 if (options.check_host_ip && ip_status == HOST_NEW) { 1006 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 1007 hostp = hostline; 1008 if (options.hash_known_hosts) { 1009 /* Add hash of host and IP separately */ 1010 r = add_host_to_hostfile(user_hostfiles[0], 1011 host, host_key, options.hash_known_hosts) && 1012 add_host_to_hostfile(user_hostfiles[0], ip, 1013 host_key, options.hash_known_hosts); 1014 } else { 1015 /* Add unhashed "host,ip" */ 1016 r = add_host_to_hostfile(user_hostfiles[0], 1017 hostline, host_key, 1018 options.hash_known_hosts); 1019 } 1020 } else { 1021 r = add_host_to_hostfile(user_hostfiles[0], host, 1022 host_key, options.hash_known_hosts); 1023 hostp = host; 1024 } 1025 1026 if (!r) 1027 logit("Failed to add the host to the list of known " 1028 "hosts (%.500s).", user_hostfiles[0]); 1029 else 1030 logit("Warning: Permanently added '%.200s' (%s) to the " 1031 "list of known hosts.", hostp, type); 1032 break; 1033 case HOST_REVOKED: 1034 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1035 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1036 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1037 error("The %s host key for %s is marked as revoked.", type, host); 1038 error("This could mean that a stolen key is being used to"); 1039 error("impersonate this host."); 1040 1041 /* 1042 * If strict host key checking is in use, the user will have 1043 * to edit the key manually and we can only abort. 1044 */ 1045 if (options.strict_host_key_checking) { 1046 error("%s host key for %.200s was revoked and you have " 1047 "requested strict checking.", type, host); 1048 goto fail; 1049 } 1050 goto continue_unsafe; 1051 1052 case HOST_CHANGED: 1053 if (want_cert) { 1054 /* 1055 * This is only a debug() since it is valid to have 1056 * CAs with wildcard DNS matches that don't match 1057 * all hosts that one might visit. 1058 */ 1059 debug("Host certificate authority does not " 1060 "match %s in %s:%lu", CA_MARKER, 1061 host_found->file, host_found->line); 1062 goto fail; 1063 } 1064 if (readonly == ROQUIET) 1065 goto fail; 1066 if (options.check_host_ip && host_ip_differ) { 1067 char *key_msg; 1068 if (ip_status == HOST_NEW) 1069 key_msg = "is unknown"; 1070 else if (ip_status == HOST_OK) 1071 key_msg = "is unchanged"; 1072 else 1073 key_msg = "has a different value"; 1074 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1075 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1076 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1077 error("The %s host key for %s has changed,", type, host); 1078 error("and the key for the corresponding IP address %s", ip); 1079 error("%s. This could either mean that", key_msg); 1080 error("DNS SPOOFING is happening or the IP address for the host"); 1081 error("and its host key have changed at the same time."); 1082 if (ip_status != HOST_NEW) 1083 error("Offending key for IP in %s:%lu", 1084 ip_found->file, ip_found->line); 1085 } 1086 /* The host key has changed. */ 1087 warn_changed_key(host_key); 1088 error("Add correct host key in %.100s to get rid of this message.", 1089 user_hostfiles[0]); 1090 error("Offending %s key in %s:%lu", key_type(host_found->key), 1091 host_found->file, host_found->line); 1092 1093 /* 1094 * If strict host key checking is in use, the user will have 1095 * to edit the key manually and we can only abort. 1096 */ 1097 if (options.strict_host_key_checking) { 1098 error("%s host key for %.200s has changed and you have " 1099 "requested strict checking.", type, host); 1100 goto fail; 1101 } 1102 1103 continue_unsafe: 1104 /* 1105 * If strict host key checking has not been requested, allow 1106 * the connection but without MITM-able authentication or 1107 * forwarding. 1108 */ 1109 if (options.password_authentication) { 1110 error("Password authentication is disabled to avoid " 1111 "man-in-the-middle attacks."); 1112 options.password_authentication = 0; 1113 cancelled_forwarding = 1; 1114 } 1115 if (options.kbd_interactive_authentication) { 1116 error("Keyboard-interactive authentication is disabled" 1117 " to avoid man-in-the-middle attacks."); 1118 options.kbd_interactive_authentication = 0; 1119 options.challenge_response_authentication = 0; 1120 cancelled_forwarding = 1; 1121 } 1122 if (options.challenge_response_authentication) { 1123 error("Challenge/response authentication is disabled" 1124 " to avoid man-in-the-middle attacks."); 1125 options.challenge_response_authentication = 0; 1126 cancelled_forwarding = 1; 1127 } 1128 if (options.forward_agent) { 1129 error("Agent forwarding is disabled to avoid " 1130 "man-in-the-middle attacks."); 1131 options.forward_agent = 0; 1132 cancelled_forwarding = 1; 1133 } 1134 if (options.forward_x11) { 1135 error("X11 forwarding is disabled to avoid " 1136 "man-in-the-middle attacks."); 1137 options.forward_x11 = 0; 1138 cancelled_forwarding = 1; 1139 } 1140 if (options.num_local_forwards > 0 || 1141 options.num_remote_forwards > 0) { 1142 error("Port forwarding is disabled to avoid " 1143 "man-in-the-middle attacks."); 1144 options.num_local_forwards = 1145 options.num_remote_forwards = 0; 1146 cancelled_forwarding = 1; 1147 } 1148 if (options.tun_open != SSH_TUNMODE_NO) { 1149 error("Tunnel forwarding is disabled to avoid " 1150 "man-in-the-middle attacks."); 1151 options.tun_open = SSH_TUNMODE_NO; 1152 cancelled_forwarding = 1; 1153 } 1154 if (options.exit_on_forward_failure && cancelled_forwarding) 1155 fatal("Error: forwarding disabled due to host key " 1156 "check failure"); 1157 1158 /* 1159 * XXX Should permit the user to change to use the new id. 1160 * This could be done by converting the host key to an 1161 * identifying sentence, tell that the host identifies itself 1162 * by that sentence, and ask the user if he/she wishes to 1163 * accept the authentication. 1164 */ 1165 break; 1166 case HOST_FOUND: 1167 fatal("internal error"); 1168 break; 1169 } 1170 1171 if (options.check_host_ip && host_status != HOST_CHANGED && 1172 ip_status == HOST_CHANGED) { 1173 snprintf(msg, sizeof(msg), 1174 "Warning: the %s host key for '%.200s' " 1175 "differs from the key for the IP address '%.128s'" 1176 "\nOffending key for IP in %s:%lu", 1177 type, host, ip, ip_found->file, ip_found->line); 1178 if (host_status == HOST_OK) { 1179 len = strlen(msg); 1180 snprintf(msg + len, sizeof(msg) - len, 1181 "\nMatching host key in %s:%lu", 1182 host_found->file, host_found->line); 1183 } 1184 if (options.strict_host_key_checking == 1) { 1185 logit("%s", msg); 1186 error("Exiting, you have requested strict checking."); 1187 goto fail; 1188 } else if (options.strict_host_key_checking == 2) { 1189 strlcat(msg, "\nAre you sure you want " 1190 "to continue connecting (yes/no)? ", sizeof(msg)); 1191 if (!confirm(msg)) 1192 goto fail; 1193 } else { 1194 logit("%s", msg); 1195 } 1196 } 1197 1198 if (!hostkey_trusted && options.update_hostkeys) { 1199 debug("%s: hostkey not known or explicitly trusted: " 1200 "disabling UpdateHostkeys", __func__); 1201 options.update_hostkeys = 0; 1202 } 1203 1204 free(ip); 1205 free(host); 1206 if (host_hostkeys != NULL) 1207 free_hostkeys(host_hostkeys); 1208 if (ip_hostkeys != NULL) 1209 free_hostkeys(ip_hostkeys); 1210 return 0; 1211 1212 fail: 1213 if (want_cert && host_status != HOST_REVOKED) { 1214 /* 1215 * No matching certificate. Downgrade cert to raw key and 1216 * search normally. 1217 */ 1218 debug("No matching CA found. Retry with plain key"); 1219 raw_key = key_from_private(host_key); 1220 if (key_drop_cert(raw_key) != 0) 1221 fatal("Couldn't drop certificate"); 1222 host_key = raw_key; 1223 goto retry; 1224 } 1225 if (raw_key != NULL) 1226 key_free(raw_key); 1227 free(ip); 1228 free(host); 1229 if (host_hostkeys != NULL) 1230 free_hostkeys(host_hostkeys); 1231 if (ip_hostkeys != NULL) 1232 free_hostkeys(ip_hostkeys); 1233 return -1; 1234 } 1235 1236 /* returns 0 if key verifies or -1 if key does NOT verify */ 1237 int 1238 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1239 { 1240 int r = -1, flags = 0; 1241 char *fp = NULL; 1242 struct sshkey *plain = NULL; 1243 1244 if ((fp = sshkey_fingerprint(host_key, 1245 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1246 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1247 r = -1; 1248 goto out; 1249 } 1250 1251 debug("Server host key: %s %s", 1252 compat20 ? sshkey_ssh_name(host_key) : sshkey_type(host_key), fp); 1253 1254 if (sshkey_equal(previous_host_key, host_key)) { 1255 debug2("%s: server host key %s %s matches cached key", 1256 __func__, sshkey_type(host_key), fp); 1257 r = 0; 1258 goto out; 1259 } 1260 1261 /* Check in RevokedHostKeys file if specified */ 1262 if (options.revoked_host_keys != NULL) { 1263 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1264 switch (r) { 1265 case 0: 1266 break; /* not revoked */ 1267 case SSH_ERR_KEY_REVOKED: 1268 error("Host key %s %s revoked by file %s", 1269 sshkey_type(host_key), fp, 1270 options.revoked_host_keys); 1271 r = -1; 1272 goto out; 1273 default: 1274 error("Error checking host key %s %s in " 1275 "revoked keys file %s: %s", sshkey_type(host_key), 1276 fp, options.revoked_host_keys, ssh_err(r)); 1277 r = -1; 1278 goto out; 1279 } 1280 } 1281 1282 if (options.verify_host_key_dns) { 1283 /* 1284 * XXX certs are not yet supported for DNS, so downgrade 1285 * them and try the plain key. 1286 */ 1287 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1288 goto out; 1289 if (sshkey_is_cert(plain)) 1290 sshkey_drop_cert(plain); 1291 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1292 if (flags & DNS_VERIFY_FOUND) { 1293 if (options.verify_host_key_dns == 1 && 1294 flags & DNS_VERIFY_MATCH && 1295 flags & DNS_VERIFY_SECURE) { 1296 r = 0; 1297 goto out; 1298 } 1299 if (flags & DNS_VERIFY_MATCH) { 1300 matching_host_key_dns = 1; 1301 } else { 1302 warn_changed_key(plain); 1303 error("Update the SSHFP RR in DNS " 1304 "with the new host key to get rid " 1305 "of this message."); 1306 } 1307 } 1308 } 1309 } 1310 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1311 options.user_hostfiles, options.num_user_hostfiles, 1312 options.system_hostfiles, options.num_system_hostfiles); 1313 1314 out: 1315 sshkey_free(plain); 1316 free(fp); 1317 if (r == 0 && host_key != NULL) { 1318 key_free(previous_host_key); 1319 previous_host_key = key_from_private(host_key); 1320 } 1321 1322 return r; 1323 } 1324 1325 /* 1326 * Starts a dialog with the server, and authenticates the current user on the 1327 * server. This does not need any extra privileges. The basic connection 1328 * to the server must already have been established before this is called. 1329 * If login fails, this function prints an error and never returns. 1330 * This function does not require super-user privileges. 1331 */ 1332 void 1333 ssh_login(Sensitive *sensitive, const char *orighost, 1334 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1335 { 1336 char *host; 1337 char *server_user, *local_user; 1338 1339 local_user = xstrdup(pw->pw_name); 1340 server_user = options.user ? options.user : local_user; 1341 1342 /* Convert the user-supplied hostname into all lowercase. */ 1343 host = xstrdup(orighost); 1344 lowercase(host); 1345 1346 /* Exchange protocol version identification strings with the server. */ 1347 ssh_exchange_identification(timeout_ms); 1348 1349 /* Put the connection into non-blocking mode. */ 1350 packet_set_nonblocking(); 1351 1352 /* key exchange */ 1353 /* authenticate user */ 1354 if (compat20) { 1355 ssh_kex2(host, hostaddr, port); 1356 ssh_userauth2(local_user, server_user, host, sensitive); 1357 } else { 1358 #ifdef WITH_SSH1 1359 ssh_kex(host, hostaddr); 1360 ssh_userauth1(local_user, server_user, host, sensitive); 1361 #else 1362 fatal("ssh1 is not unsupported"); 1363 #endif 1364 } 1365 free(local_user); 1366 } 1367 1368 void 1369 ssh_put_password(char *password) 1370 { 1371 int size; 1372 char *padded; 1373 1374 if (datafellows & SSH_BUG_PASSWORDPAD) { 1375 packet_put_cstring(password); 1376 return; 1377 } 1378 size = roundup(strlen(password) + 1, 32); 1379 padded = xcalloc(1, size); 1380 strlcpy(padded, password, size); 1381 packet_put_string(padded, size); 1382 explicit_bzero(padded, size); 1383 free(padded); 1384 } 1385 1386 /* print all known host keys for a given host, but skip keys of given type */ 1387 static int 1388 show_other_keys(struct hostkeys *hostkeys, Key *key) 1389 { 1390 int type[] = { 1391 KEY_RSA1, 1392 KEY_RSA, 1393 KEY_DSA, 1394 KEY_ECDSA, 1395 KEY_ED25519, 1396 -1 1397 }; 1398 int i, ret = 0; 1399 char *fp, *ra; 1400 const struct hostkey_entry *found; 1401 1402 for (i = 0; type[i] != -1; i++) { 1403 if (type[i] == key->type) 1404 continue; 1405 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1406 continue; 1407 fp = sshkey_fingerprint(found->key, 1408 options.fingerprint_hash, SSH_FP_DEFAULT); 1409 ra = sshkey_fingerprint(found->key, 1410 options.fingerprint_hash, SSH_FP_RANDOMART); 1411 if (fp == NULL || ra == NULL) 1412 fatal("%s: sshkey_fingerprint fail", __func__); 1413 logit("WARNING: %s key found for host %s\n" 1414 "in %s:%lu\n" 1415 "%s key fingerprint %s.", 1416 key_type(found->key), 1417 found->host, found->file, found->line, 1418 key_type(found->key), fp); 1419 if (options.visual_host_key) 1420 logit("%s", ra); 1421 free(ra); 1422 free(fp); 1423 ret = 1; 1424 } 1425 return ret; 1426 } 1427 1428 static void 1429 warn_changed_key(Key *host_key) 1430 { 1431 char *fp; 1432 1433 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1434 SSH_FP_DEFAULT); 1435 if (fp == NULL) 1436 fatal("%s: sshkey_fingerprint fail", __func__); 1437 1438 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1439 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1440 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1441 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1442 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1443 error("It is also possible that a host key has just been changed."); 1444 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1445 key_type(host_key), fp); 1446 error("Please contact your system administrator."); 1447 1448 free(fp); 1449 } 1450 1451 /* 1452 * Execute a local command 1453 */ 1454 int 1455 ssh_local_cmd(const char *args) 1456 { 1457 char *shell; 1458 pid_t pid; 1459 int status; 1460 void (*osighand)(int); 1461 1462 if (!options.permit_local_command || 1463 args == NULL || !*args) 1464 return (1); 1465 1466 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1467 shell = _PATH_BSHELL; 1468 1469 osighand = signal(SIGCHLD, SIG_DFL); 1470 pid = fork(); 1471 if (pid == 0) { 1472 signal(SIGPIPE, SIG_DFL); 1473 debug3("Executing %s -c \"%s\"", shell, args); 1474 execl(shell, shell, "-c", args, (char *)NULL); 1475 error("Couldn't execute %s -c \"%s\": %s", 1476 shell, args, strerror(errno)); 1477 _exit(1); 1478 } else if (pid == -1) 1479 fatal("fork failed: %.100s", strerror(errno)); 1480 while (waitpid(pid, &status, 0) == -1) 1481 if (errno != EINTR) 1482 fatal("Couldn't wait for child: %s", strerror(errno)); 1483 signal(SIGCHLD, osighand); 1484 1485 if (!WIFEXITED(status)) 1486 return (1); 1487 1488 return (WEXITSTATUS(status)); 1489 } 1490