1 /* $OpenBSD: sshconnect.c,v 1.263 2015/08/20 22:32:42 deraadt Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) 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 18 #include <sys/param.h> /* roundup */ 19 #include <sys/types.h> 20 #include <sys/wait.h> 21 #include <sys/stat.h> 22 #include <sys/socket.h> 23 #ifdef HAVE_SYS_TIME_H 24 # include <sys/time.h> 25 #endif 26 27 #include <netinet/in.h> 28 #include <arpa/inet.h> 29 30 #include <ctype.h> 31 #include <errno.h> 32 #include <fcntl.h> 33 #include <netdb.h> 34 #ifdef HAVE_PATHS_H 35 #include <paths.h> 36 #endif 37 #include <pwd.h> 38 #include <signal.h> 39 #include <stdarg.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include "xmalloc.h" 46 #include "key.h" 47 #include "hostfile.h" 48 #include "ssh.h" 49 #include "rsa.h" 50 #include "buffer.h" 51 #include "packet.h" 52 #include "uidswap.h" 53 #include "compat.h" 54 #include "key.h" 55 #include "sshconnect.h" 56 #include "hostfile.h" 57 #include "log.h" 58 #include "misc.h" 59 #include "readconf.h" 60 #include "atomicio.h" 61 #include "dns.h" 62 #include "roaming.h" 63 #include "monitor_fdpass.h" 64 #include "ssh2.h" 65 #include "version.h" 66 #include "authfile.h" 67 #include "ssherr.h" 68 69 char *client_version_string = NULL; 70 char *server_version_string = NULL; 71 Key *previous_host_key = NULL; 72 73 static int matching_host_key_dns = 0; 74 75 static pid_t proxy_command_pid = 0; 76 77 /* import */ 78 extern Options options; 79 extern char *__progname; 80 extern uid_t original_real_uid; 81 extern uid_t original_effective_uid; 82 83 static int show_other_keys(struct hostkeys *, Key *); 84 static void warn_changed_key(Key *); 85 86 /* Expand a proxy command */ 87 static char * 88 expand_proxy_command(const char *proxy_command, const char *user, 89 const char *host, int port) 90 { 91 char *tmp, *ret, strport[NI_MAXSERV]; 92 93 snprintf(strport, sizeof strport, "%d", port); 94 xasprintf(&tmp, "exec %s", proxy_command); 95 ret = percent_expand(tmp, "h", host, "p", strport, 96 "r", options.user, (char *)NULL); 97 free(tmp); 98 return ret; 99 } 100 101 /* 102 * Connect to the given ssh server using a proxy command that passes a 103 * a connected fd back to us. 104 */ 105 static int 106 ssh_proxy_fdpass_connect(const char *host, u_short port, 107 const char *proxy_command) 108 { 109 char *command_string; 110 int sp[2], sock; 111 pid_t pid; 112 char *shell; 113 114 if ((shell = getenv("SHELL")) == NULL) 115 shell = _PATH_BSHELL; 116 117 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 118 fatal("Could not create socketpair to communicate with " 119 "proxy dialer: %.100s", strerror(errno)); 120 121 command_string = expand_proxy_command(proxy_command, options.user, 122 host, port); 123 debug("Executing proxy dialer command: %.500s", command_string); 124 125 /* Fork and execute the proxy command. */ 126 if ((pid = fork()) == 0) { 127 char *argv[10]; 128 129 /* Child. Permanently give up superuser privileges. */ 130 permanently_drop_suid(original_real_uid); 131 132 close(sp[1]); 133 /* Redirect stdin and stdout. */ 134 if (sp[0] != 0) { 135 if (dup2(sp[0], 0) < 0) 136 perror("dup2 stdin"); 137 } 138 if (sp[0] != 1) { 139 if (dup2(sp[0], 1) < 0) 140 perror("dup2 stdout"); 141 } 142 if (sp[0] >= 2) 143 close(sp[0]); 144 145 /* 146 * Stderr is left as it is so that error messages get 147 * printed on the user's terminal. 148 */ 149 argv[0] = shell; 150 argv[1] = "-c"; 151 argv[2] = command_string; 152 argv[3] = NULL; 153 154 /* 155 * Execute the proxy command. 156 * Note that we gave up any extra privileges above. 157 */ 158 execv(argv[0], argv); 159 perror(argv[0]); 160 exit(1); 161 } 162 /* Parent. */ 163 if (pid < 0) 164 fatal("fork failed: %.100s", strerror(errno)); 165 close(sp[0]); 166 free(command_string); 167 168 if ((sock = mm_receive_fd(sp[1])) == -1) 169 fatal("proxy dialer did not pass back a connection"); 170 171 while (waitpid(pid, NULL, 0) == -1) 172 if (errno != EINTR) 173 fatal("Couldn't wait for child: %s", strerror(errno)); 174 175 /* Set the connection file descriptors. */ 176 packet_set_connection(sock, sock); 177 178 return 0; 179 } 180 181 /* 182 * Connect to the given ssh server using a proxy command. 183 */ 184 static int 185 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 186 { 187 char *command_string; 188 int pin[2], pout[2]; 189 pid_t pid; 190 char *shell; 191 192 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 193 shell = _PATH_BSHELL; 194 195 /* Create pipes for communicating with the proxy. */ 196 if (pipe(pin) < 0 || pipe(pout) < 0) 197 fatal("Could not create pipes to communicate with the proxy: %.100s", 198 strerror(errno)); 199 200 command_string = expand_proxy_command(proxy_command, options.user, 201 host, port); 202 debug("Executing proxy command: %.500s", command_string); 203 204 /* Fork and execute the proxy command. */ 205 if ((pid = fork()) == 0) { 206 char *argv[10]; 207 208 /* Child. Permanently give up superuser privileges. */ 209 permanently_drop_suid(original_real_uid); 210 211 /* Redirect stdin and stdout. */ 212 close(pin[1]); 213 if (pin[0] != 0) { 214 if (dup2(pin[0], 0) < 0) 215 perror("dup2 stdin"); 216 close(pin[0]); 217 } 218 close(pout[0]); 219 if (dup2(pout[1], 1) < 0) 220 perror("dup2 stdout"); 221 /* Cannot be 1 because pin allocated two descriptors. */ 222 close(pout[1]); 223 224 /* Stderr is left as it is so that error messages get 225 printed on the user's terminal. */ 226 argv[0] = shell; 227 argv[1] = "-c"; 228 argv[2] = command_string; 229 argv[3] = NULL; 230 231 /* Execute the proxy command. Note that we gave up any 232 extra privileges above. */ 233 signal(SIGPIPE, SIG_DFL); 234 execv(argv[0], argv); 235 perror(argv[0]); 236 exit(1); 237 } 238 /* Parent. */ 239 if (pid < 0) 240 fatal("fork failed: %.100s", strerror(errno)); 241 else 242 proxy_command_pid = pid; /* save pid to clean up later */ 243 244 /* Close child side of the descriptors. */ 245 close(pin[0]); 246 close(pout[1]); 247 248 /* Free the command name. */ 249 free(command_string); 250 251 /* Set the connection file descriptors. */ 252 packet_set_connection(pout[0], pin[1]); 253 254 /* Indicate OK return */ 255 return 0; 256 } 257 258 void 259 ssh_kill_proxy_command(void) 260 { 261 /* 262 * Send SIGHUP to proxy command if used. We don't wait() in 263 * case it hangs and instead rely on init to reap the child 264 */ 265 if (proxy_command_pid > 1) 266 kill(proxy_command_pid, SIGHUP); 267 } 268 269 /* 270 * Creates a (possibly privileged) socket for use as the ssh connection. 271 */ 272 static int 273 ssh_create_socket(int privileged, struct addrinfo *ai) 274 { 275 int sock, r, gaierr; 276 struct addrinfo hints, *res = NULL; 277 278 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 279 if (sock < 0) { 280 error("socket: %s", strerror(errno)); 281 return -1; 282 } 283 fcntl(sock, F_SETFD, FD_CLOEXEC); 284 285 /* Bind the socket to an alternative local IP address */ 286 if (options.bind_address == NULL && !privileged) 287 return sock; 288 289 if (options.bind_address) { 290 memset(&hints, 0, sizeof(hints)); 291 hints.ai_family = ai->ai_family; 292 hints.ai_socktype = ai->ai_socktype; 293 hints.ai_protocol = ai->ai_protocol; 294 hints.ai_flags = AI_PASSIVE; 295 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 296 if (gaierr) { 297 error("getaddrinfo: %s: %s", options.bind_address, 298 ssh_gai_strerror(gaierr)); 299 close(sock); 300 return -1; 301 } 302 } 303 /* 304 * If we are running as root and want to connect to a privileged 305 * port, bind our own socket to a privileged port. 306 */ 307 if (privileged) { 308 PRIV_START; 309 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 310 PRIV_END; 311 if (r < 0) { 312 error("bindresvport_sa: af=%d %s", ai->ai_family, 313 strerror(errno)); 314 goto fail; 315 } 316 } else { 317 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 318 error("bind: %s: %s", options.bind_address, 319 strerror(errno)); 320 fail: 321 close(sock); 322 freeaddrinfo(res); 323 return -1; 324 } 325 } 326 if (res != NULL) 327 freeaddrinfo(res); 328 return sock; 329 } 330 331 static int 332 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 333 socklen_t addrlen, int *timeoutp) 334 { 335 fd_set *fdset; 336 struct timeval tv, t_start; 337 socklen_t optlen; 338 int optval, rc, result = -1; 339 340 gettimeofday(&t_start, NULL); 341 342 if (*timeoutp <= 0) { 343 result = connect(sockfd, serv_addr, addrlen); 344 goto done; 345 } 346 347 set_nonblock(sockfd); 348 rc = connect(sockfd, serv_addr, addrlen); 349 if (rc == 0) { 350 unset_nonblock(sockfd); 351 result = 0; 352 goto done; 353 } 354 if (errno != EINPROGRESS) { 355 result = -1; 356 goto done; 357 } 358 359 fdset = xcalloc(howmany(sockfd + 1, NFDBITS), 360 sizeof(fd_mask)); 361 FD_SET(sockfd, fdset); 362 ms_to_timeval(&tv, *timeoutp); 363 364 for (;;) { 365 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 366 if (rc != -1 || errno != EINTR) 367 break; 368 } 369 370 switch (rc) { 371 case 0: 372 /* Timed out */ 373 errno = ETIMEDOUT; 374 break; 375 case -1: 376 /* Select error */ 377 debug("select: %s", strerror(errno)); 378 break; 379 case 1: 380 /* Completed or failed */ 381 optval = 0; 382 optlen = sizeof(optval); 383 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 384 &optlen) == -1) { 385 debug("getsockopt: %s", strerror(errno)); 386 break; 387 } 388 if (optval != 0) { 389 errno = optval; 390 break; 391 } 392 result = 0; 393 unset_nonblock(sockfd); 394 break; 395 default: 396 /* Should not occur */ 397 fatal("Bogus return (%d) from select()", rc); 398 } 399 400 free(fdset); 401 402 done: 403 if (result == 0 && *timeoutp > 0) { 404 ms_subtract_diff(&t_start, timeoutp); 405 if (*timeoutp <= 0) { 406 errno = ETIMEDOUT; 407 result = -1; 408 } 409 } 410 411 return (result); 412 } 413 414 /* 415 * Opens a TCP/IP connection to the remote server on the given host. 416 * The address of the remote host will be returned in hostaddr. 417 * If port is 0, the default port will be used. If needpriv is true, 418 * a privileged port will be allocated to make the connection. 419 * This requires super-user privileges if needpriv is true. 420 * Connection_attempts specifies the maximum number of tries (one per 421 * second). If proxy_command is non-NULL, it specifies the command (with %h 422 * and %p substituted for host and port, respectively) to use to contact 423 * the daemon. 424 */ 425 static int 426 ssh_connect_direct(const char *host, struct addrinfo *aitop, 427 struct sockaddr_storage *hostaddr, u_short port, int family, 428 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 429 { 430 int on = 1; 431 int sock = -1, attempt; 432 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 433 struct addrinfo *ai; 434 435 debug2("ssh_connect: needpriv %d", needpriv); 436 437 for (attempt = 0; attempt < connection_attempts; attempt++) { 438 if (attempt > 0) { 439 /* Sleep a moment before retrying. */ 440 sleep(1); 441 debug("Trying again..."); 442 } 443 /* 444 * Loop through addresses for this host, and try each one in 445 * sequence until the connection succeeds. 446 */ 447 for (ai = aitop; ai; ai = ai->ai_next) { 448 if (ai->ai_family != AF_INET && 449 ai->ai_family != AF_INET6) 450 continue; 451 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 452 ntop, sizeof(ntop), strport, sizeof(strport), 453 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 454 error("ssh_connect: getnameinfo failed"); 455 continue; 456 } 457 debug("Connecting to %.200s [%.100s] port %s.", 458 host, ntop, strport); 459 460 /* Create a socket for connecting. */ 461 sock = ssh_create_socket(needpriv, ai); 462 if (sock < 0) 463 /* Any error is already output */ 464 continue; 465 466 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 467 timeout_ms) >= 0) { 468 /* Successful connection. */ 469 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 470 break; 471 } else { 472 debug("connect to address %s port %s: %s", 473 ntop, strport, strerror(errno)); 474 close(sock); 475 sock = -1; 476 } 477 } 478 if (sock != -1) 479 break; /* Successful connection. */ 480 } 481 482 /* Return failure if we didn't get a successful connection. */ 483 if (sock == -1) { 484 error("ssh: connect to host %s port %s: %s", 485 host, strport, strerror(errno)); 486 return (-1); 487 } 488 489 debug("Connection established."); 490 491 /* Set SO_KEEPALIVE if requested. */ 492 if (want_keepalive && 493 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 494 sizeof(on)) < 0) 495 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 496 497 /* Set the connection. */ 498 packet_set_connection(sock, sock); 499 500 return 0; 501 } 502 503 int 504 ssh_connect(const char *host, struct addrinfo *addrs, 505 struct sockaddr_storage *hostaddr, u_short port, int family, 506 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 507 { 508 if (options.proxy_command == NULL) { 509 return ssh_connect_direct(host, addrs, hostaddr, port, family, 510 connection_attempts, timeout_ms, want_keepalive, needpriv); 511 } else if (strcmp(options.proxy_command, "-") == 0) { 512 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 513 return 0; /* Always succeeds */ 514 } else if (options.proxy_use_fdpass) { 515 return ssh_proxy_fdpass_connect(host, port, 516 options.proxy_command); 517 } 518 return ssh_proxy_connect(host, port, options.proxy_command); 519 } 520 521 static void 522 send_client_banner(int connection_out, int minor1) 523 { 524 /* Send our own protocol version identification. */ 525 if (compat20) { 526 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n", 527 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION); 528 } else { 529 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n", 530 PROTOCOL_MAJOR_1, minor1, SSH_VERSION); 531 } 532 if (roaming_atomicio(vwrite, connection_out, client_version_string, 533 strlen(client_version_string)) != strlen(client_version_string)) 534 fatal("write: %.100s", strerror(errno)); 535 chop(client_version_string); 536 debug("Local version string %.100s", client_version_string); 537 } 538 539 /* 540 * Waits for the server identification string, and sends our own 541 * identification string. 542 */ 543 void 544 ssh_exchange_identification(int timeout_ms) 545 { 546 char buf[256], remote_version[256]; /* must be same size! */ 547 int remote_major, remote_minor, mismatch; 548 int connection_in = packet_get_connection_in(); 549 int connection_out = packet_get_connection_out(); 550 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 551 u_int i, n; 552 size_t len; 553 int fdsetsz, remaining, rc; 554 struct timeval t_start, t_remaining; 555 fd_set *fdset; 556 557 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 558 fdset = xcalloc(1, fdsetsz); 559 560 /* 561 * If we are SSH2-only then we can send the banner immediately and 562 * save a round-trip. 563 */ 564 if (options.protocol == SSH_PROTO_2) { 565 enable_compat20(); 566 send_client_banner(connection_out, 0); 567 client_banner_sent = 1; 568 } 569 570 /* Read other side's version identification. */ 571 remaining = timeout_ms; 572 for (n = 0;;) { 573 for (i = 0; i < sizeof(buf) - 1; i++) { 574 if (timeout_ms > 0) { 575 gettimeofday(&t_start, NULL); 576 ms_to_timeval(&t_remaining, remaining); 577 FD_SET(connection_in, fdset); 578 rc = select(connection_in + 1, fdset, NULL, 579 fdset, &t_remaining); 580 ms_subtract_diff(&t_start, &remaining); 581 if (rc == 0 || remaining <= 0) 582 fatal("Connection timed out during " 583 "banner exchange"); 584 if (rc == -1) { 585 if (errno == EINTR) 586 continue; 587 fatal("ssh_exchange_identification: " 588 "select: %s", strerror(errno)); 589 } 590 } 591 592 len = roaming_atomicio(read, connection_in, &buf[i], 1); 593 594 if (len != 1 && errno == EPIPE) 595 fatal("ssh_exchange_identification: " 596 "Connection closed by remote host"); 597 else if (len != 1) 598 fatal("ssh_exchange_identification: " 599 "read: %.100s", strerror(errno)); 600 if (buf[i] == '\r') { 601 buf[i] = '\n'; 602 buf[i + 1] = 0; 603 continue; /**XXX wait for \n */ 604 } 605 if (buf[i] == '\n') { 606 buf[i + 1] = 0; 607 break; 608 } 609 if (++n > 65536) 610 fatal("ssh_exchange_identification: " 611 "No banner received"); 612 } 613 buf[sizeof(buf) - 1] = 0; 614 if (strncmp(buf, "SSH-", 4) == 0) 615 break; 616 debug("ssh_exchange_identification: %s", buf); 617 } 618 server_version_string = xstrdup(buf); 619 free(fdset); 620 621 /* 622 * Check that the versions match. In future this might accept 623 * several versions and set appropriate flags to handle them. 624 */ 625 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 626 &remote_major, &remote_minor, remote_version) != 3) 627 fatal("Bad remote protocol version identification: '%.100s'", buf); 628 debug("Remote protocol version %d.%d, remote software version %.100s", 629 remote_major, remote_minor, remote_version); 630 631 active_state->compat = compat_datafellows(remote_version); 632 mismatch = 0; 633 634 switch (remote_major) { 635 case 1: 636 if (remote_minor == 99 && 637 (options.protocol & SSH_PROTO_2) && 638 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 639 enable_compat20(); 640 break; 641 } 642 if (!(options.protocol & SSH_PROTO_1)) { 643 mismatch = 1; 644 break; 645 } 646 if (remote_minor < 3) { 647 fatal("Remote machine has too old SSH software version."); 648 } else if (remote_minor == 3 || remote_minor == 4) { 649 /* We speak 1.3, too. */ 650 enable_compat13(); 651 minor1 = 3; 652 if (options.forward_agent) { 653 logit("Agent forwarding disabled for protocol 1.3"); 654 options.forward_agent = 0; 655 } 656 } 657 break; 658 case 2: 659 if (options.protocol & SSH_PROTO_2) { 660 enable_compat20(); 661 break; 662 } 663 /* FALLTHROUGH */ 664 default: 665 mismatch = 1; 666 break; 667 } 668 if (mismatch) 669 fatal("Protocol major versions differ: %d vs. %d", 670 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 671 remote_major); 672 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 673 fatal("Server version \"%.100s\" uses unsafe key agreement; " 674 "refusing connection", remote_version); 675 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 676 logit("Server version \"%.100s\" uses unsafe RSA signature " 677 "scheme; disabling use of RSA keys", remote_version); 678 if (!client_banner_sent) 679 send_client_banner(connection_out, minor1); 680 chop(server_version_string); 681 } 682 683 /* defaults to 'no' */ 684 static int 685 confirm(const char *prompt) 686 { 687 const char *msg, *again = "Please type 'yes' or 'no': "; 688 char *p; 689 int ret = -1; 690 691 if (options.batch_mode) 692 return 0; 693 for (msg = prompt;;msg = again) { 694 p = read_passphrase(msg, RP_ECHO); 695 if (p == NULL || 696 (p[0] == '\0') || (p[0] == '\n') || 697 strncasecmp(p, "no", 2) == 0) 698 ret = 0; 699 if (p && strncasecmp(p, "yes", 3) == 0) 700 ret = 1; 701 free(p); 702 if (ret != -1) 703 return ret; 704 } 705 } 706 707 static int 708 check_host_cert(const char *host, const Key *host_key) 709 { 710 const char *reason; 711 712 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 713 error("%s", reason); 714 return 0; 715 } 716 if (buffer_len(host_key->cert->critical) != 0) { 717 error("Certificate for %s contains unsupported " 718 "critical options(s)", host); 719 return 0; 720 } 721 return 1; 722 } 723 724 static int 725 sockaddr_is_local(struct sockaddr *hostaddr) 726 { 727 switch (hostaddr->sa_family) { 728 case AF_INET: 729 return (ntohl(((struct sockaddr_in *)hostaddr)-> 730 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 731 case AF_INET6: 732 return IN6_IS_ADDR_LOOPBACK( 733 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 734 default: 735 return 0; 736 } 737 } 738 739 /* 740 * Prepare the hostname and ip address strings that are used to lookup 741 * host keys in known_hosts files. These may have a port number appended. 742 */ 743 void 744 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 745 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 746 { 747 char ntop[NI_MAXHOST]; 748 socklen_t addrlen; 749 750 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 751 case -1: 752 addrlen = 0; 753 break; 754 case AF_INET: 755 addrlen = sizeof(struct sockaddr_in); 756 break; 757 case AF_INET6: 758 addrlen = sizeof(struct sockaddr_in6); 759 break; 760 default: 761 addrlen = sizeof(struct sockaddr); 762 break; 763 } 764 765 /* 766 * We don't have the remote ip-address for connections 767 * using a proxy command 768 */ 769 if (hostfile_ipaddr != NULL) { 770 if (options.proxy_command == NULL) { 771 if (getnameinfo(hostaddr, addrlen, 772 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 773 fatal("%s: getnameinfo failed", __func__); 774 *hostfile_ipaddr = put_host_port(ntop, port); 775 } else { 776 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 777 "command>"); 778 } 779 } 780 781 /* 782 * Allow the user to record the key under a different name or 783 * differentiate a non-standard port. This is useful for ssh 784 * tunneling over forwarded connections or if you run multiple 785 * sshd's on different ports on the same machine. 786 */ 787 if (hostfile_hostname != NULL) { 788 if (options.host_key_alias != NULL) { 789 *hostfile_hostname = xstrdup(options.host_key_alias); 790 debug("using hostkeyalias: %s", *hostfile_hostname); 791 } else { 792 *hostfile_hostname = put_host_port(hostname, port); 793 } 794 } 795 } 796 797 /* 798 * check whether the supplied host key is valid, return -1 if the key 799 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 800 */ 801 #define RDRW 0 802 #define RDONLY 1 803 #define ROQUIET 2 804 static int 805 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 806 Key *host_key, int readonly, 807 char **user_hostfiles, u_int num_user_hostfiles, 808 char **system_hostfiles, u_int num_system_hostfiles) 809 { 810 HostStatus host_status; 811 HostStatus ip_status; 812 Key *raw_key = NULL; 813 char *ip = NULL, *host = NULL; 814 char hostline[1000], *hostp, *fp, *ra; 815 char msg[1024]; 816 const char *type; 817 const struct hostkey_entry *host_found, *ip_found; 818 int len, cancelled_forwarding = 0; 819 int local = sockaddr_is_local(hostaddr); 820 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 821 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 822 struct hostkeys *host_hostkeys, *ip_hostkeys; 823 u_int i; 824 825 /* 826 * Force accepting of the host key for loopback/localhost. The 827 * problem is that if the home directory is NFS-mounted to multiple 828 * machines, localhost will refer to a different machine in each of 829 * them, and the user will get bogus HOST_CHANGED warnings. This 830 * essentially disables host authentication for localhost; however, 831 * this is probably not a real problem. 832 */ 833 if (options.no_host_authentication_for_localhost == 1 && local && 834 options.host_key_alias == NULL) { 835 debug("Forcing accepting of host key for " 836 "loopback/localhost."); 837 return 0; 838 } 839 840 /* 841 * Prepare the hostname and address strings used for hostkey lookup. 842 * In some cases, these will have a port number appended. 843 */ 844 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 845 846 /* 847 * Turn off check_host_ip if the connection is to localhost, via proxy 848 * command or if we don't have a hostname to compare with 849 */ 850 if (options.check_host_ip && (local || 851 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 852 options.check_host_ip = 0; 853 854 host_hostkeys = init_hostkeys(); 855 for (i = 0; i < num_user_hostfiles; i++) 856 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 857 for (i = 0; i < num_system_hostfiles; i++) 858 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 859 860 ip_hostkeys = NULL; 861 if (!want_cert && options.check_host_ip) { 862 ip_hostkeys = init_hostkeys(); 863 for (i = 0; i < num_user_hostfiles; i++) 864 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 865 for (i = 0; i < num_system_hostfiles; i++) 866 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 867 } 868 869 retry: 870 /* Reload these as they may have changed on cert->key downgrade */ 871 want_cert = key_is_cert(host_key); 872 type = key_type(host_key); 873 874 /* 875 * Check if the host key is present in the user's list of known 876 * hosts or in the systemwide list. 877 */ 878 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 879 &host_found); 880 881 /* 882 * Also perform check for the ip address, skip the check if we are 883 * localhost, looking for a certificate, or the hostname was an ip 884 * address to begin with. 885 */ 886 if (!want_cert && ip_hostkeys != NULL) { 887 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 888 &ip_found); 889 if (host_status == HOST_CHANGED && 890 (ip_status != HOST_CHANGED || 891 (ip_found != NULL && 892 !key_equal(ip_found->key, host_found->key)))) 893 host_ip_differ = 1; 894 } else 895 ip_status = host_status; 896 897 switch (host_status) { 898 case HOST_OK: 899 /* The host is known and the key matches. */ 900 debug("Host '%.200s' is known and matches the %s host %s.", 901 host, type, want_cert ? "certificate" : "key"); 902 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 903 host_found->file, host_found->line); 904 if (want_cert && !check_host_cert(hostname, host_key)) 905 goto fail; 906 if (options.check_host_ip && ip_status == HOST_NEW) { 907 if (readonly || want_cert) 908 logit("%s host key for IP address " 909 "'%.128s' not in list of known hosts.", 910 type, ip); 911 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 912 host_key, options.hash_known_hosts)) 913 logit("Failed to add the %s host key for IP " 914 "address '%.128s' to the list of known " 915 "hosts (%.500s).", type, ip, 916 user_hostfiles[0]); 917 else 918 logit("Warning: Permanently added the %s host " 919 "key for IP address '%.128s' to the list " 920 "of known hosts.", type, ip); 921 } else if (options.visual_host_key) { 922 fp = sshkey_fingerprint(host_key, 923 options.fingerprint_hash, SSH_FP_DEFAULT); 924 ra = sshkey_fingerprint(host_key, 925 options.fingerprint_hash, SSH_FP_RANDOMART); 926 if (fp == NULL || ra == NULL) 927 fatal("%s: sshkey_fingerprint fail", __func__); 928 logit("Host key fingerprint is %s\n%s\n", fp, ra); 929 free(ra); 930 free(fp); 931 } 932 hostkey_trusted = 1; 933 break; 934 case HOST_NEW: 935 if (options.host_key_alias == NULL && port != 0 && 936 port != SSH_DEFAULT_PORT) { 937 debug("checking without port identifier"); 938 if (check_host_key(hostname, hostaddr, 0, host_key, 939 ROQUIET, user_hostfiles, num_user_hostfiles, 940 system_hostfiles, num_system_hostfiles) == 0) { 941 debug("found matching key w/out port"); 942 break; 943 } 944 } 945 if (readonly || want_cert) 946 goto fail; 947 /* The host is new. */ 948 if (options.strict_host_key_checking == 1) { 949 /* 950 * User has requested strict host key checking. We 951 * will not add the host key automatically. The only 952 * alternative left is to abort. 953 */ 954 error("No %s host key is known for %.200s and you " 955 "have requested strict checking.", type, host); 956 goto fail; 957 } else if (options.strict_host_key_checking == 2) { 958 char msg1[1024], msg2[1024]; 959 960 if (show_other_keys(host_hostkeys, host_key)) 961 snprintf(msg1, sizeof(msg1), 962 "\nbut keys of different type are already" 963 " known for this host."); 964 else 965 snprintf(msg1, sizeof(msg1), "."); 966 /* The default */ 967 fp = sshkey_fingerprint(host_key, 968 options.fingerprint_hash, SSH_FP_DEFAULT); 969 ra = sshkey_fingerprint(host_key, 970 options.fingerprint_hash, SSH_FP_RANDOMART); 971 if (fp == NULL || ra == NULL) 972 fatal("%s: sshkey_fingerprint fail", __func__); 973 msg2[0] = '\0'; 974 if (options.verify_host_key_dns) { 975 if (matching_host_key_dns) 976 snprintf(msg2, sizeof(msg2), 977 "Matching host key fingerprint" 978 " found in DNS.\n"); 979 else 980 snprintf(msg2, sizeof(msg2), 981 "No matching host key fingerprint" 982 " found in DNS.\n"); 983 } 984 snprintf(msg, sizeof(msg), 985 "The authenticity of host '%.200s (%s)' can't be " 986 "established%s\n" 987 "%s key fingerprint is %s.%s%s\n%s" 988 "Are you sure you want to continue connecting " 989 "(yes/no)? ", 990 host, ip, msg1, type, fp, 991 options.visual_host_key ? "\n" : "", 992 options.visual_host_key ? ra : "", 993 msg2); 994 free(ra); 995 free(fp); 996 if (!confirm(msg)) 997 goto fail; 998 hostkey_trusted = 1; /* user explicitly confirmed */ 999 } 1000 /* 1001 * If not in strict mode, add the key automatically to the 1002 * local known_hosts file. 1003 */ 1004 if (options.check_host_ip && ip_status == HOST_NEW) { 1005 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 1006 hostp = hostline; 1007 if (options.hash_known_hosts) { 1008 /* Add hash of host and IP separately */ 1009 r = add_host_to_hostfile(user_hostfiles[0], 1010 host, host_key, options.hash_known_hosts) && 1011 add_host_to_hostfile(user_hostfiles[0], ip, 1012 host_key, options.hash_known_hosts); 1013 } else { 1014 /* Add unhashed "host,ip" */ 1015 r = add_host_to_hostfile(user_hostfiles[0], 1016 hostline, host_key, 1017 options.hash_known_hosts); 1018 } 1019 } else { 1020 r = add_host_to_hostfile(user_hostfiles[0], host, 1021 host_key, options.hash_known_hosts); 1022 hostp = host; 1023 } 1024 1025 if (!r) 1026 logit("Failed to add the host to the list of known " 1027 "hosts (%.500s).", user_hostfiles[0]); 1028 else 1029 logit("Warning: Permanently added '%.200s' (%s) to the " 1030 "list of known hosts.", hostp, type); 1031 break; 1032 case HOST_REVOKED: 1033 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1034 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1035 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1036 error("The %s host key for %s is marked as revoked.", type, host); 1037 error("This could mean that a stolen key is being used to"); 1038 error("impersonate this host."); 1039 1040 /* 1041 * If strict host key checking is in use, the user will have 1042 * to edit the key manually and we can only abort. 1043 */ 1044 if (options.strict_host_key_checking) { 1045 error("%s host key for %.200s was revoked and you have " 1046 "requested strict checking.", type, host); 1047 goto fail; 1048 } 1049 goto continue_unsafe; 1050 1051 case HOST_CHANGED: 1052 if (want_cert) { 1053 /* 1054 * This is only a debug() since it is valid to have 1055 * CAs with wildcard DNS matches that don't match 1056 * all hosts that one might visit. 1057 */ 1058 debug("Host certificate authority does not " 1059 "match %s in %s:%lu", CA_MARKER, 1060 host_found->file, host_found->line); 1061 goto fail; 1062 } 1063 if (readonly == ROQUIET) 1064 goto fail; 1065 if (options.check_host_ip && host_ip_differ) { 1066 char *key_msg; 1067 if (ip_status == HOST_NEW) 1068 key_msg = "is unknown"; 1069 else if (ip_status == HOST_OK) 1070 key_msg = "is unchanged"; 1071 else 1072 key_msg = "has a different value"; 1073 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1074 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1075 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1076 error("The %s host key for %s has changed,", type, host); 1077 error("and the key for the corresponding IP address %s", ip); 1078 error("%s. This could either mean that", key_msg); 1079 error("DNS SPOOFING is happening or the IP address for the host"); 1080 error("and its host key have changed at the same time."); 1081 if (ip_status != HOST_NEW) 1082 error("Offending key for IP in %s:%lu", 1083 ip_found->file, ip_found->line); 1084 } 1085 /* The host key has changed. */ 1086 warn_changed_key(host_key); 1087 error("Add correct host key in %.100s to get rid of this message.", 1088 user_hostfiles[0]); 1089 error("Offending %s key in %s:%lu", key_type(host_found->key), 1090 host_found->file, host_found->line); 1091 1092 /* 1093 * If strict host key checking is in use, the user will have 1094 * to edit the key manually and we can only abort. 1095 */ 1096 if (options.strict_host_key_checking) { 1097 error("%s host key for %.200s has changed and you have " 1098 "requested strict checking.", type, host); 1099 goto fail; 1100 } 1101 1102 continue_unsafe: 1103 /* 1104 * If strict host key checking has not been requested, allow 1105 * the connection but without MITM-able authentication or 1106 * forwarding. 1107 */ 1108 if (options.password_authentication) { 1109 error("Password authentication is disabled to avoid " 1110 "man-in-the-middle attacks."); 1111 options.password_authentication = 0; 1112 cancelled_forwarding = 1; 1113 } 1114 if (options.kbd_interactive_authentication) { 1115 error("Keyboard-interactive authentication is disabled" 1116 " to avoid man-in-the-middle attacks."); 1117 options.kbd_interactive_authentication = 0; 1118 options.challenge_response_authentication = 0; 1119 cancelled_forwarding = 1; 1120 } 1121 if (options.challenge_response_authentication) { 1122 error("Challenge/response authentication is disabled" 1123 " to avoid man-in-the-middle attacks."); 1124 options.challenge_response_authentication = 0; 1125 cancelled_forwarding = 1; 1126 } 1127 if (options.forward_agent) { 1128 error("Agent forwarding is disabled to avoid " 1129 "man-in-the-middle attacks."); 1130 options.forward_agent = 0; 1131 cancelled_forwarding = 1; 1132 } 1133 if (options.forward_x11) { 1134 error("X11 forwarding is disabled to avoid " 1135 "man-in-the-middle attacks."); 1136 options.forward_x11 = 0; 1137 cancelled_forwarding = 1; 1138 } 1139 if (options.num_local_forwards > 0 || 1140 options.num_remote_forwards > 0) { 1141 error("Port forwarding is disabled to avoid " 1142 "man-in-the-middle attacks."); 1143 options.num_local_forwards = 1144 options.num_remote_forwards = 0; 1145 cancelled_forwarding = 1; 1146 } 1147 if (options.tun_open != SSH_TUNMODE_NO) { 1148 error("Tunnel forwarding is disabled to avoid " 1149 "man-in-the-middle attacks."); 1150 options.tun_open = SSH_TUNMODE_NO; 1151 cancelled_forwarding = 1; 1152 } 1153 if (options.exit_on_forward_failure && cancelled_forwarding) 1154 fatal("Error: forwarding disabled due to host key " 1155 "check failure"); 1156 1157 /* 1158 * XXX Should permit the user to change to use the new id. 1159 * This could be done by converting the host key to an 1160 * identifying sentence, tell that the host identifies itself 1161 * by that sentence, and ask the user if he/she wishes to 1162 * accept the authentication. 1163 */ 1164 break; 1165 case HOST_FOUND: 1166 fatal("internal error"); 1167 break; 1168 } 1169 1170 if (options.check_host_ip && host_status != HOST_CHANGED && 1171 ip_status == HOST_CHANGED) { 1172 snprintf(msg, sizeof(msg), 1173 "Warning: the %s host key for '%.200s' " 1174 "differs from the key for the IP address '%.128s'" 1175 "\nOffending key for IP in %s:%lu", 1176 type, host, ip, ip_found->file, ip_found->line); 1177 if (host_status == HOST_OK) { 1178 len = strlen(msg); 1179 snprintf(msg + len, sizeof(msg) - len, 1180 "\nMatching host key in %s:%lu", 1181 host_found->file, host_found->line); 1182 } 1183 if (options.strict_host_key_checking == 1) { 1184 logit("%s", msg); 1185 error("Exiting, you have requested strict checking."); 1186 goto fail; 1187 } else if (options.strict_host_key_checking == 2) { 1188 strlcat(msg, "\nAre you sure you want " 1189 "to continue connecting (yes/no)? ", sizeof(msg)); 1190 if (!confirm(msg)) 1191 goto fail; 1192 } else { 1193 logit("%s", msg); 1194 } 1195 } 1196 1197 if (!hostkey_trusted && options.update_hostkeys) { 1198 debug("%s: hostkey not known or explicitly trusted: " 1199 "disabling UpdateHostkeys", __func__); 1200 options.update_hostkeys = 0; 1201 } 1202 1203 free(ip); 1204 free(host); 1205 if (host_hostkeys != NULL) 1206 free_hostkeys(host_hostkeys); 1207 if (ip_hostkeys != NULL) 1208 free_hostkeys(ip_hostkeys); 1209 return 0; 1210 1211 fail: 1212 if (want_cert && host_status != HOST_REVOKED) { 1213 /* 1214 * No matching certificate. Downgrade cert to raw key and 1215 * search normally. 1216 */ 1217 debug("No matching CA found. Retry with plain key"); 1218 raw_key = key_from_private(host_key); 1219 if (key_drop_cert(raw_key) != 0) 1220 fatal("Couldn't drop certificate"); 1221 host_key = raw_key; 1222 goto retry; 1223 } 1224 if (raw_key != NULL) 1225 key_free(raw_key); 1226 free(ip); 1227 free(host); 1228 if (host_hostkeys != NULL) 1229 free_hostkeys(host_hostkeys); 1230 if (ip_hostkeys != NULL) 1231 free_hostkeys(ip_hostkeys); 1232 return -1; 1233 } 1234 1235 /* returns 0 if key verifies or -1 if key does NOT verify */ 1236 int 1237 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1238 { 1239 int r = -1, flags = 0; 1240 char *fp = NULL; 1241 struct sshkey *plain = NULL; 1242 1243 if ((fp = sshkey_fingerprint(host_key, 1244 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1245 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1246 r = -1; 1247 goto out; 1248 } 1249 1250 debug("Server host key: %s %s", 1251 compat20 ? sshkey_ssh_name(host_key) : sshkey_type(host_key), fp); 1252 1253 if (sshkey_equal(previous_host_key, host_key)) { 1254 debug2("%s: server host key %s %s matches cached key", 1255 __func__, sshkey_type(host_key), fp); 1256 r = 0; 1257 goto out; 1258 } 1259 1260 /* Check in RevokedHostKeys file if specified */ 1261 if (options.revoked_host_keys != NULL) { 1262 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1263 switch (r) { 1264 case 0: 1265 break; /* not revoked */ 1266 case SSH_ERR_KEY_REVOKED: 1267 error("Host key %s %s revoked by file %s", 1268 sshkey_type(host_key), fp, 1269 options.revoked_host_keys); 1270 r = -1; 1271 goto out; 1272 default: 1273 error("Error checking host key %s %s in " 1274 "revoked keys file %s: %s", sshkey_type(host_key), 1275 fp, options.revoked_host_keys, ssh_err(r)); 1276 r = -1; 1277 goto out; 1278 } 1279 } 1280 1281 if (options.verify_host_key_dns) { 1282 /* 1283 * XXX certs are not yet supported for DNS, so downgrade 1284 * them and try the plain key. 1285 */ 1286 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1287 goto out; 1288 if (sshkey_is_cert(plain)) 1289 sshkey_drop_cert(plain); 1290 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1291 if (flags & DNS_VERIFY_FOUND) { 1292 if (options.verify_host_key_dns == 1 && 1293 flags & DNS_VERIFY_MATCH && 1294 flags & DNS_VERIFY_SECURE) { 1295 r = 0; 1296 goto out; 1297 } 1298 if (flags & DNS_VERIFY_MATCH) { 1299 matching_host_key_dns = 1; 1300 } else { 1301 warn_changed_key(plain); 1302 error("Update the SSHFP RR in DNS " 1303 "with the new host key to get rid " 1304 "of this message."); 1305 } 1306 } 1307 } 1308 } 1309 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1310 options.user_hostfiles, options.num_user_hostfiles, 1311 options.system_hostfiles, options.num_system_hostfiles); 1312 1313 out: 1314 sshkey_free(plain); 1315 free(fp); 1316 if (r == 0 && host_key != NULL) { 1317 key_free(previous_host_key); 1318 previous_host_key = key_from_private(host_key); 1319 } 1320 1321 return r; 1322 } 1323 1324 /* 1325 * Starts a dialog with the server, and authenticates the current user on the 1326 * server. This does not need any extra privileges. The basic connection 1327 * to the server must already have been established before this is called. 1328 * If login fails, this function prints an error and never returns. 1329 * This function does not require super-user privileges. 1330 */ 1331 void 1332 ssh_login(Sensitive *sensitive, const char *orighost, 1333 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1334 { 1335 char *host; 1336 char *server_user, *local_user; 1337 1338 local_user = xstrdup(pw->pw_name); 1339 server_user = options.user ? options.user : local_user; 1340 1341 /* Convert the user-supplied hostname into all lowercase. */ 1342 host = xstrdup(orighost); 1343 lowercase(host); 1344 1345 /* Exchange protocol version identification strings with the server. */ 1346 ssh_exchange_identification(timeout_ms); 1347 1348 /* Put the connection into non-blocking mode. */ 1349 packet_set_nonblocking(); 1350 1351 /* key exchange */ 1352 /* authenticate user */ 1353 debug("Authenticating to %s:%d as '%s'", host, port, server_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 supported"); 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
