1 /* $OpenBSD: sshconnect.c,v 1.251 2014/07/15 15:54:14 millert 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 <sys/types.h> 17 #include <sys/wait.h> 18 #include <sys/stat.h> 19 #include <sys/socket.h> 20 #include <sys/time.h> 21 22 #include <netinet/in.h> 23 24 #include <ctype.h> 25 #include <errno.h> 26 #include <fcntl.h> 27 #include <netdb.h> 28 #include <paths.h> 29 #include <signal.h> 30 #include <pwd.h> 31 #include <stdio.h> 32 #include <stdlib.h> 33 #include <string.h> 34 #include <unistd.h> 35 36 #include "xmalloc.h" 37 #include "ssh.h" 38 #include "rsa.h" 39 #include "buffer.h" 40 #include "packet.h" 41 #include "uidswap.h" 42 #include "compat.h" 43 #include "key.h" 44 #include "sshconnect.h" 45 #include "hostfile.h" 46 #include "log.h" 47 #include "misc.h" 48 #include "readconf.h" 49 #include "atomicio.h" 50 #include "dns.h" 51 #include "roaming.h" 52 #include "monitor_fdpass.h" 53 #include "ssh2.h" 54 #include "version.h" 55 56 char *client_version_string = NULL; 57 char *server_version_string = NULL; 58 Key *previous_host_key = NULL; 59 60 static int matching_host_key_dns = 0; 61 62 static pid_t proxy_command_pid = 0; 63 64 /* import */ 65 extern Options options; 66 extern char *__progname; 67 extern uid_t original_real_uid; 68 extern uid_t original_effective_uid; 69 70 static int show_other_keys(struct hostkeys *, Key *); 71 static void warn_changed_key(Key *); 72 73 /* Expand a proxy command */ 74 static char * 75 expand_proxy_command(const char *proxy_command, const char *user, 76 const char *host, int port) 77 { 78 char *tmp, *ret, strport[NI_MAXSERV]; 79 80 snprintf(strport, sizeof strport, "%d", port); 81 xasprintf(&tmp, "exec %s", proxy_command); 82 ret = percent_expand(tmp, "h", host, "p", strport, 83 "r", options.user, (char *)NULL); 84 free(tmp); 85 return ret; 86 } 87 88 /* 89 * Connect to the given ssh server using a proxy command that passes a 90 * a connected fd back to us. 91 */ 92 static int 93 ssh_proxy_fdpass_connect(const char *host, u_short port, 94 const char *proxy_command) 95 { 96 char *command_string; 97 int sp[2], sock; 98 pid_t pid; 99 char *shell; 100 101 if ((shell = getenv("SHELL")) == NULL) 102 shell = _PATH_BSHELL; 103 104 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 105 fatal("Could not create socketpair to communicate with " 106 "proxy dialer: %.100s", strerror(errno)); 107 108 command_string = expand_proxy_command(proxy_command, options.user, 109 host, port); 110 debug("Executing proxy dialer command: %.500s", command_string); 111 112 /* Fork and execute the proxy command. */ 113 if ((pid = fork()) == 0) { 114 char *argv[10]; 115 116 /* Child. Permanently give up superuser privileges. */ 117 permanently_drop_suid(original_real_uid); 118 119 close(sp[1]); 120 /* Redirect stdin and stdout. */ 121 if (sp[0] != 0) { 122 if (dup2(sp[0], 0) < 0) 123 perror("dup2 stdin"); 124 } 125 if (sp[0] != 1) { 126 if (dup2(sp[0], 1) < 0) 127 perror("dup2 stdout"); 128 } 129 if (sp[0] >= 2) 130 close(sp[0]); 131 132 /* 133 * Stderr is left as it is so that error messages get 134 * printed on the user's terminal. 135 */ 136 argv[0] = shell; 137 argv[1] = "-c"; 138 argv[2] = command_string; 139 argv[3] = NULL; 140 141 /* 142 * Execute the proxy command. 143 * Note that we gave up any extra privileges above. 144 */ 145 execv(argv[0], argv); 146 perror(argv[0]); 147 exit(1); 148 } 149 /* Parent. */ 150 if (pid < 0) 151 fatal("fork failed: %.100s", strerror(errno)); 152 close(sp[0]); 153 free(command_string); 154 155 if ((sock = mm_receive_fd(sp[1])) == -1) 156 fatal("proxy dialer did not pass back a connection"); 157 158 while (waitpid(pid, NULL, 0) == -1) 159 if (errno != EINTR) 160 fatal("Couldn't wait for child: %s", strerror(errno)); 161 162 /* Set the connection file descriptors. */ 163 packet_set_connection(sock, sock); 164 165 return 0; 166 } 167 168 /* 169 * Connect to the given ssh server using a proxy command. 170 */ 171 static int 172 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 173 { 174 char *command_string; 175 int pin[2], pout[2]; 176 pid_t pid; 177 char *shell; 178 179 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 180 shell = _PATH_BSHELL; 181 182 /* Create pipes for communicating with the proxy. */ 183 if (pipe(pin) < 0 || pipe(pout) < 0) 184 fatal("Could not create pipes to communicate with the proxy: %.100s", 185 strerror(errno)); 186 187 command_string = expand_proxy_command(proxy_command, options.user, 188 host, port); 189 debug("Executing proxy command: %.500s", command_string); 190 191 /* Fork and execute the proxy command. */ 192 if ((pid = fork()) == 0) { 193 char *argv[10]; 194 195 /* Child. Permanently give up superuser privileges. */ 196 permanently_drop_suid(original_real_uid); 197 198 /* Redirect stdin and stdout. */ 199 close(pin[1]); 200 if (pin[0] != 0) { 201 if (dup2(pin[0], 0) < 0) 202 perror("dup2 stdin"); 203 close(pin[0]); 204 } 205 close(pout[0]); 206 if (dup2(pout[1], 1) < 0) 207 perror("dup2 stdout"); 208 /* Cannot be 1 because pin allocated two descriptors. */ 209 close(pout[1]); 210 211 /* Stderr is left as it is so that error messages get 212 printed on the user's terminal. */ 213 argv[0] = shell; 214 argv[1] = "-c"; 215 argv[2] = command_string; 216 argv[3] = NULL; 217 218 /* Execute the proxy command. Note that we gave up any 219 extra privileges above. */ 220 signal(SIGPIPE, SIG_DFL); 221 execv(argv[0], argv); 222 perror(argv[0]); 223 exit(1); 224 } 225 /* Parent. */ 226 if (pid < 0) 227 fatal("fork failed: %.100s", strerror(errno)); 228 else 229 proxy_command_pid = pid; /* save pid to clean up later */ 230 231 /* Close child side of the descriptors. */ 232 close(pin[0]); 233 close(pout[1]); 234 235 /* Free the command name. */ 236 free(command_string); 237 238 /* Set the connection file descriptors. */ 239 packet_set_connection(pout[0], pin[1]); 240 241 /* Indicate OK return */ 242 return 0; 243 } 244 245 void 246 ssh_kill_proxy_command(void) 247 { 248 /* 249 * Send SIGHUP to proxy command if used. We don't wait() in 250 * case it hangs and instead rely on init to reap the child 251 */ 252 if (proxy_command_pid > 1) 253 kill(proxy_command_pid, SIGHUP); 254 } 255 256 /* 257 * Creates a (possibly privileged) socket for use as the ssh connection. 258 */ 259 static int 260 ssh_create_socket(int privileged, struct addrinfo *ai) 261 { 262 int sock, r, gaierr; 263 struct addrinfo hints, *res = NULL; 264 265 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 266 if (sock < 0) { 267 error("socket: %s", strerror(errno)); 268 return -1; 269 } 270 fcntl(sock, F_SETFD, FD_CLOEXEC); 271 272 /* Bind the socket to an alternative local IP address */ 273 if (options.bind_address == NULL && !privileged) 274 return sock; 275 276 if (options.bind_address) { 277 memset(&hints, 0, sizeof(hints)); 278 hints.ai_family = ai->ai_family; 279 hints.ai_socktype = ai->ai_socktype; 280 hints.ai_protocol = ai->ai_protocol; 281 hints.ai_flags = AI_PASSIVE; 282 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 283 if (gaierr) { 284 error("getaddrinfo: %s: %s", options.bind_address, 285 ssh_gai_strerror(gaierr)); 286 close(sock); 287 return -1; 288 } 289 } 290 /* 291 * If we are running as root and want to connect to a privileged 292 * port, bind our own socket to a privileged port. 293 */ 294 if (privileged) { 295 PRIV_START; 296 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 297 PRIV_END; 298 if (r < 0) { 299 error("bindresvport_sa: af=%d %s", ai->ai_family, 300 strerror(errno)); 301 goto fail; 302 } 303 } else { 304 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 305 error("bind: %s: %s", options.bind_address, 306 strerror(errno)); 307 fail: 308 close(sock); 309 freeaddrinfo(res); 310 return -1; 311 } 312 } 313 if (res != NULL) 314 freeaddrinfo(res); 315 return sock; 316 } 317 318 static int 319 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 320 socklen_t addrlen, int *timeoutp) 321 { 322 fd_set *fdset; 323 struct timeval tv, t_start; 324 socklen_t optlen; 325 int optval, rc, result = -1; 326 327 gettimeofday(&t_start, NULL); 328 329 if (*timeoutp <= 0) { 330 result = connect(sockfd, serv_addr, addrlen); 331 goto done; 332 } 333 334 set_nonblock(sockfd); 335 rc = connect(sockfd, serv_addr, addrlen); 336 if (rc == 0) { 337 unset_nonblock(sockfd); 338 result = 0; 339 goto done; 340 } 341 if (errno != EINPROGRESS) { 342 result = -1; 343 goto done; 344 } 345 346 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), 347 sizeof(fd_mask)); 348 FD_SET(sockfd, fdset); 349 ms_to_timeval(&tv, *timeoutp); 350 351 for (;;) { 352 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 353 if (rc != -1 || errno != EINTR) 354 break; 355 } 356 357 switch (rc) { 358 case 0: 359 /* Timed out */ 360 errno = ETIMEDOUT; 361 break; 362 case -1: 363 /* Select error */ 364 debug("select: %s", strerror(errno)); 365 break; 366 case 1: 367 /* Completed or failed */ 368 optval = 0; 369 optlen = sizeof(optval); 370 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 371 &optlen) == -1) { 372 debug("getsockopt: %s", strerror(errno)); 373 break; 374 } 375 if (optval != 0) { 376 errno = optval; 377 break; 378 } 379 result = 0; 380 unset_nonblock(sockfd); 381 break; 382 default: 383 /* Should not occur */ 384 fatal("Bogus return (%d) from select()", rc); 385 } 386 387 free(fdset); 388 389 done: 390 if (result == 0 && *timeoutp > 0) { 391 ms_subtract_diff(&t_start, timeoutp); 392 if (*timeoutp <= 0) { 393 errno = ETIMEDOUT; 394 result = -1; 395 } 396 } 397 398 return (result); 399 } 400 401 /* 402 * Opens a TCP/IP connection to the remote server on the given host. 403 * The address of the remote host will be returned in hostaddr. 404 * If port is 0, the default port will be used. If needpriv is true, 405 * a privileged port will be allocated to make the connection. 406 * This requires super-user privileges if needpriv is true. 407 * Connection_attempts specifies the maximum number of tries (one per 408 * second). If proxy_command is non-NULL, it specifies the command (with %h 409 * and %p substituted for host and port, respectively) to use to contact 410 * the daemon. 411 */ 412 static int 413 ssh_connect_direct(const char *host, struct addrinfo *aitop, 414 struct sockaddr_storage *hostaddr, u_short port, int family, 415 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 416 { 417 int on = 1; 418 int sock = -1, attempt; 419 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 420 struct addrinfo *ai; 421 422 debug2("ssh_connect: needpriv %d", needpriv); 423 424 for (attempt = 0; attempt < connection_attempts; attempt++) { 425 if (attempt > 0) { 426 /* Sleep a moment before retrying. */ 427 sleep(1); 428 debug("Trying again..."); 429 } 430 /* 431 * Loop through addresses for this host, and try each one in 432 * sequence until the connection succeeds. 433 */ 434 for (ai = aitop; ai; ai = ai->ai_next) { 435 if (ai->ai_family != AF_INET && 436 ai->ai_family != AF_INET6) 437 continue; 438 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 439 ntop, sizeof(ntop), strport, sizeof(strport), 440 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 441 error("ssh_connect: getnameinfo failed"); 442 continue; 443 } 444 debug("Connecting to %.200s [%.100s] port %s.", 445 host, ntop, strport); 446 447 /* Create a socket for connecting. */ 448 sock = ssh_create_socket(needpriv, ai); 449 if (sock < 0) 450 /* Any error is already output */ 451 continue; 452 453 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 454 timeout_ms) >= 0) { 455 /* Successful connection. */ 456 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 457 break; 458 } else { 459 debug("connect to address %s port %s: %s", 460 ntop, strport, strerror(errno)); 461 close(sock); 462 sock = -1; 463 } 464 } 465 if (sock != -1) 466 break; /* Successful connection. */ 467 } 468 469 /* Return failure if we didn't get a successful connection. */ 470 if (sock == -1) { 471 error("ssh: connect to host %s port %s: %s", 472 host, strport, strerror(errno)); 473 return (-1); 474 } 475 476 debug("Connection established."); 477 478 /* Set SO_KEEPALIVE if requested. */ 479 if (want_keepalive && 480 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 481 sizeof(on)) < 0) 482 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 483 484 /* Set the connection. */ 485 packet_set_connection(sock, sock); 486 487 return 0; 488 } 489 490 int 491 ssh_connect(const char *host, struct addrinfo *addrs, 492 struct sockaddr_storage *hostaddr, u_short port, int family, 493 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 494 { 495 if (options.proxy_command == NULL) { 496 return ssh_connect_direct(host, addrs, hostaddr, port, family, 497 connection_attempts, timeout_ms, want_keepalive, needpriv); 498 } else if (strcmp(options.proxy_command, "-") == 0) { 499 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 500 return 0; /* Always succeeds */ 501 } else if (options.proxy_use_fdpass) { 502 return ssh_proxy_fdpass_connect(host, port, 503 options.proxy_command); 504 } 505 return ssh_proxy_connect(host, port, options.proxy_command); 506 } 507 508 static void 509 send_client_banner(int connection_out, int minor1) 510 { 511 /* Send our own protocol version identification. */ 512 if (compat20) { 513 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n", 514 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION); 515 } else { 516 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n", 517 PROTOCOL_MAJOR_1, minor1, SSH_VERSION); 518 } 519 if (roaming_atomicio(vwrite, connection_out, client_version_string, 520 strlen(client_version_string)) != strlen(client_version_string)) 521 fatal("write: %.100s", strerror(errno)); 522 chop(client_version_string); 523 debug("Local version string %.100s", client_version_string); 524 } 525 526 /* 527 * Waits for the server identification string, and sends our own 528 * identification string. 529 */ 530 void 531 ssh_exchange_identification(int timeout_ms) 532 { 533 char buf[256], remote_version[256]; /* must be same size! */ 534 int remote_major, remote_minor, mismatch; 535 int connection_in = packet_get_connection_in(); 536 int connection_out = packet_get_connection_out(); 537 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 538 u_int i, n; 539 size_t len; 540 int fdsetsz, remaining, rc; 541 struct timeval t_start, t_remaining; 542 fd_set *fdset; 543 544 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 545 fdset = xcalloc(1, fdsetsz); 546 547 /* 548 * If we are SSH2-only then we can send the banner immediately and 549 * save a round-trip. 550 */ 551 if (options.protocol == SSH_PROTO_2) { 552 enable_compat20(); 553 send_client_banner(connection_out, 0); 554 client_banner_sent = 1; 555 } 556 557 /* Read other side's version identification. */ 558 remaining = timeout_ms; 559 for (n = 0;;) { 560 for (i = 0; i < sizeof(buf) - 1; i++) { 561 if (timeout_ms > 0) { 562 gettimeofday(&t_start, NULL); 563 ms_to_timeval(&t_remaining, remaining); 564 FD_SET(connection_in, fdset); 565 rc = select(connection_in + 1, fdset, NULL, 566 fdset, &t_remaining); 567 ms_subtract_diff(&t_start, &remaining); 568 if (rc == 0 || remaining <= 0) 569 fatal("Connection timed out during " 570 "banner exchange"); 571 if (rc == -1) { 572 if (errno == EINTR) 573 continue; 574 fatal("ssh_exchange_identification: " 575 "select: %s", strerror(errno)); 576 } 577 } 578 579 len = roaming_atomicio(read, connection_in, &buf[i], 1); 580 581 if (len != 1 && errno == EPIPE) 582 fatal("ssh_exchange_identification: " 583 "Connection closed by remote host"); 584 else if (len != 1) 585 fatal("ssh_exchange_identification: " 586 "read: %.100s", strerror(errno)); 587 if (buf[i] == '\r') { 588 buf[i] = '\n'; 589 buf[i + 1] = 0; 590 continue; /**XXX wait for \n */ 591 } 592 if (buf[i] == '\n') { 593 buf[i + 1] = 0; 594 break; 595 } 596 if (++n > 65536) 597 fatal("ssh_exchange_identification: " 598 "No banner received"); 599 } 600 buf[sizeof(buf) - 1] = 0; 601 if (strncmp(buf, "SSH-", 4) == 0) 602 break; 603 debug("ssh_exchange_identification: %s", buf); 604 } 605 server_version_string = xstrdup(buf); 606 free(fdset); 607 608 /* 609 * Check that the versions match. In future this might accept 610 * several versions and set appropriate flags to handle them. 611 */ 612 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 613 &remote_major, &remote_minor, remote_version) != 3) 614 fatal("Bad remote protocol version identification: '%.100s'", buf); 615 debug("Remote protocol version %d.%d, remote software version %.100s", 616 remote_major, remote_minor, remote_version); 617 618 compat_datafellows(remote_version); 619 mismatch = 0; 620 621 switch (remote_major) { 622 case 1: 623 if (remote_minor == 99 && 624 (options.protocol & SSH_PROTO_2) && 625 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 626 enable_compat20(); 627 break; 628 } 629 if (!(options.protocol & SSH_PROTO_1)) { 630 mismatch = 1; 631 break; 632 } 633 if (remote_minor < 3) { 634 fatal("Remote machine has too old SSH software version."); 635 } else if (remote_minor == 3 || remote_minor == 4) { 636 /* We speak 1.3, too. */ 637 enable_compat13(); 638 minor1 = 3; 639 if (options.forward_agent) { 640 logit("Agent forwarding disabled for protocol 1.3"); 641 options.forward_agent = 0; 642 } 643 } 644 break; 645 case 2: 646 if (options.protocol & SSH_PROTO_2) { 647 enable_compat20(); 648 break; 649 } 650 /* FALLTHROUGH */ 651 default: 652 mismatch = 1; 653 break; 654 } 655 if (mismatch) 656 fatal("Protocol major versions differ: %d vs. %d", 657 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 658 remote_major); 659 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 660 fatal("Server version \"%.100s\" uses unsafe key agreement; " 661 "refusing connection", remote_version); 662 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 663 logit("Server version \"%.100s\" uses unsafe RSA signature " 664 "scheme; disabling use of RSA keys", remote_version); 665 if (!client_banner_sent) 666 send_client_banner(connection_out, minor1); 667 chop(server_version_string); 668 } 669 670 /* defaults to 'no' */ 671 static int 672 confirm(const char *prompt) 673 { 674 const char *msg, *again = "Please type 'yes' or 'no': "; 675 char *p; 676 int ret = -1; 677 678 if (options.batch_mode) 679 return 0; 680 for (msg = prompt;;msg = again) { 681 p = read_passphrase(msg, RP_ECHO); 682 if (p == NULL || 683 (p[0] == '\0') || (p[0] == '\n') || 684 strncasecmp(p, "no", 2) == 0) 685 ret = 0; 686 if (p && strncasecmp(p, "yes", 3) == 0) 687 ret = 1; 688 free(p); 689 if (ret != -1) 690 return ret; 691 } 692 } 693 694 static int 695 check_host_cert(const char *host, const Key *host_key) 696 { 697 const char *reason; 698 699 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 700 error("%s", reason); 701 return 0; 702 } 703 if (buffer_len(host_key->cert->critical) != 0) { 704 error("Certificate for %s contains unsupported " 705 "critical options(s)", host); 706 return 0; 707 } 708 return 1; 709 } 710 711 static int 712 sockaddr_is_local(struct sockaddr *hostaddr) 713 { 714 switch (hostaddr->sa_family) { 715 case AF_INET: 716 return (ntohl(((struct sockaddr_in *)hostaddr)-> 717 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 718 case AF_INET6: 719 return IN6_IS_ADDR_LOOPBACK( 720 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 721 default: 722 return 0; 723 } 724 } 725 726 /* 727 * Prepare the hostname and ip address strings that are used to lookup 728 * host keys in known_hosts files. These may have a port number appended. 729 */ 730 void 731 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 732 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 733 { 734 char ntop[NI_MAXHOST]; 735 736 /* 737 * We don't have the remote ip-address for connections 738 * using a proxy command 739 */ 740 if (hostfile_ipaddr != NULL) { 741 if (options.proxy_command == NULL) { 742 if (getnameinfo(hostaddr, hostaddr->sa_len, 743 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 744 fatal("check_host_key: getnameinfo failed"); 745 *hostfile_ipaddr = put_host_port(ntop, port); 746 } else { 747 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 748 "command>"); 749 } 750 } 751 752 /* 753 * Allow the user to record the key under a different name or 754 * differentiate a non-standard port. This is useful for ssh 755 * tunneling over forwarded connections or if you run multiple 756 * sshd's on different ports on the same machine. 757 */ 758 if (hostfile_hostname != NULL) { 759 if (options.host_key_alias != NULL) { 760 *hostfile_hostname = xstrdup(options.host_key_alias); 761 debug("using hostkeyalias: %s", *hostfile_hostname); 762 } else { 763 *hostfile_hostname = put_host_port(hostname, port); 764 } 765 } 766 } 767 768 /* 769 * check whether the supplied host key is valid, return -1 if the key 770 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 771 */ 772 #define RDRW 0 773 #define RDONLY 1 774 #define ROQUIET 2 775 static int 776 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 777 Key *host_key, int readonly, 778 char **user_hostfiles, u_int num_user_hostfiles, 779 char **system_hostfiles, u_int num_system_hostfiles) 780 { 781 HostStatus host_status; 782 HostStatus ip_status; 783 Key *raw_key = NULL; 784 char *ip = NULL, *host = NULL; 785 char hostline[1000], *hostp, *fp, *ra; 786 char msg[1024]; 787 const char *type; 788 const struct hostkey_entry *host_found, *ip_found; 789 int len, cancelled_forwarding = 0; 790 int local = sockaddr_is_local(hostaddr); 791 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 792 struct hostkeys *host_hostkeys, *ip_hostkeys; 793 u_int i; 794 795 /* 796 * Force accepting of the host key for loopback/localhost. The 797 * problem is that if the home directory is NFS-mounted to multiple 798 * machines, localhost will refer to a different machine in each of 799 * them, and the user will get bogus HOST_CHANGED warnings. This 800 * essentially disables host authentication for localhost; however, 801 * this is probably not a real problem. 802 */ 803 if (options.no_host_authentication_for_localhost == 1 && local && 804 options.host_key_alias == NULL) { 805 debug("Forcing accepting of host key for " 806 "loopback/localhost."); 807 return 0; 808 } 809 810 /* 811 * Prepare the hostname and address strings used for hostkey lookup. 812 * In some cases, these will have a port number appended. 813 */ 814 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 815 816 /* 817 * Turn off check_host_ip if the connection is to localhost, via proxy 818 * command or if we don't have a hostname to compare with 819 */ 820 if (options.check_host_ip && (local || 821 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 822 options.check_host_ip = 0; 823 824 host_hostkeys = init_hostkeys(); 825 for (i = 0; i < num_user_hostfiles; i++) 826 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 827 for (i = 0; i < num_system_hostfiles; i++) 828 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 829 830 ip_hostkeys = NULL; 831 if (!want_cert && options.check_host_ip) { 832 ip_hostkeys = init_hostkeys(); 833 for (i = 0; i < num_user_hostfiles; i++) 834 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 835 for (i = 0; i < num_system_hostfiles; i++) 836 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 837 } 838 839 retry: 840 /* Reload these as they may have changed on cert->key downgrade */ 841 want_cert = key_is_cert(host_key); 842 type = key_type(host_key); 843 844 /* 845 * Check if the host key is present in the user's list of known 846 * hosts or in the systemwide list. 847 */ 848 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 849 &host_found); 850 851 /* 852 * Also perform check for the ip address, skip the check if we are 853 * localhost, looking for a certificate, or the hostname was an ip 854 * address to begin with. 855 */ 856 if (!want_cert && ip_hostkeys != NULL) { 857 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 858 &ip_found); 859 if (host_status == HOST_CHANGED && 860 (ip_status != HOST_CHANGED || 861 (ip_found != NULL && 862 !key_equal(ip_found->key, host_found->key)))) 863 host_ip_differ = 1; 864 } else 865 ip_status = host_status; 866 867 switch (host_status) { 868 case HOST_OK: 869 /* The host is known and the key matches. */ 870 debug("Host '%.200s' is known and matches the %s host %s.", 871 host, type, want_cert ? "certificate" : "key"); 872 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 873 host_found->file, host_found->line); 874 if (want_cert && !check_host_cert(hostname, host_key)) 875 goto fail; 876 if (options.check_host_ip && ip_status == HOST_NEW) { 877 if (readonly || want_cert) 878 logit("%s host key for IP address " 879 "'%.128s' not in list of known hosts.", 880 type, ip); 881 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 882 host_key, options.hash_known_hosts)) 883 logit("Failed to add the %s host key for IP " 884 "address '%.128s' to the list of known " 885 "hosts (%.30s).", type, ip, 886 user_hostfiles[0]); 887 else 888 logit("Warning: Permanently added the %s host " 889 "key for IP address '%.128s' to the list " 890 "of known hosts.", type, ip); 891 } else if (options.visual_host_key) { 892 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 893 ra = key_fingerprint(host_key, SSH_FP_MD5, 894 SSH_FP_RANDOMART); 895 logit("Host key fingerprint is %s\n%s\n", fp, ra); 896 free(ra); 897 free(fp); 898 } 899 break; 900 case HOST_NEW: 901 if (options.host_key_alias == NULL && port != 0 && 902 port != SSH_DEFAULT_PORT) { 903 debug("checking without port identifier"); 904 if (check_host_key(hostname, hostaddr, 0, host_key, 905 ROQUIET, user_hostfiles, num_user_hostfiles, 906 system_hostfiles, num_system_hostfiles) == 0) { 907 debug("found matching key w/out port"); 908 break; 909 } 910 } 911 if (readonly || want_cert) 912 goto fail; 913 /* The host is new. */ 914 if (options.strict_host_key_checking == 1) { 915 /* 916 * User has requested strict host key checking. We 917 * will not add the host key automatically. The only 918 * alternative left is to abort. 919 */ 920 error("No %s host key is known for %.200s and you " 921 "have requested strict checking.", type, host); 922 goto fail; 923 } else if (options.strict_host_key_checking == 2) { 924 char msg1[1024], msg2[1024]; 925 926 if (show_other_keys(host_hostkeys, host_key)) 927 snprintf(msg1, sizeof(msg1), 928 "\nbut keys of different type are already" 929 " known for this host."); 930 else 931 snprintf(msg1, sizeof(msg1), "."); 932 /* The default */ 933 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 934 ra = key_fingerprint(host_key, SSH_FP_MD5, 935 SSH_FP_RANDOMART); 936 msg2[0] = '\0'; 937 if (options.verify_host_key_dns) { 938 if (matching_host_key_dns) 939 snprintf(msg2, sizeof(msg2), 940 "Matching host key fingerprint" 941 " found in DNS.\n"); 942 else 943 snprintf(msg2, sizeof(msg2), 944 "No matching host key fingerprint" 945 " found in DNS.\n"); 946 } 947 snprintf(msg, sizeof(msg), 948 "The authenticity of host '%.200s (%s)' can't be " 949 "established%s\n" 950 "%s key fingerprint is %s.%s%s\n%s" 951 "Are you sure you want to continue connecting " 952 "(yes/no)? ", 953 host, ip, msg1, type, fp, 954 options.visual_host_key ? "\n" : "", 955 options.visual_host_key ? ra : "", 956 msg2); 957 free(ra); 958 free(fp); 959 if (!confirm(msg)) 960 goto fail; 961 } 962 /* 963 * If not in strict mode, add the key automatically to the 964 * local known_hosts file. 965 */ 966 if (options.check_host_ip && ip_status == HOST_NEW) { 967 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 968 hostp = hostline; 969 if (options.hash_known_hosts) { 970 /* Add hash of host and IP separately */ 971 r = add_host_to_hostfile(user_hostfiles[0], 972 host, host_key, options.hash_known_hosts) && 973 add_host_to_hostfile(user_hostfiles[0], ip, 974 host_key, options.hash_known_hosts); 975 } else { 976 /* Add unhashed "host,ip" */ 977 r = add_host_to_hostfile(user_hostfiles[0], 978 hostline, host_key, 979 options.hash_known_hosts); 980 } 981 } else { 982 r = add_host_to_hostfile(user_hostfiles[0], host, 983 host_key, options.hash_known_hosts); 984 hostp = host; 985 } 986 987 if (!r) 988 logit("Failed to add the host to the list of known " 989 "hosts (%.500s).", user_hostfiles[0]); 990 else 991 logit("Warning: Permanently added '%.200s' (%s) to the " 992 "list of known hosts.", hostp, type); 993 break; 994 case HOST_REVOKED: 995 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 996 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 997 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 998 error("The %s host key for %s is marked as revoked.", type, host); 999 error("This could mean that a stolen key is being used to"); 1000 error("impersonate this host."); 1001 1002 /* 1003 * If strict host key checking is in use, the user will have 1004 * to edit the key manually and we can only abort. 1005 */ 1006 if (options.strict_host_key_checking) { 1007 error("%s host key for %.200s was revoked and you have " 1008 "requested strict checking.", type, host); 1009 goto fail; 1010 } 1011 goto continue_unsafe; 1012 1013 case HOST_CHANGED: 1014 if (want_cert) { 1015 /* 1016 * This is only a debug() since it is valid to have 1017 * CAs with wildcard DNS matches that don't match 1018 * all hosts that one might visit. 1019 */ 1020 debug("Host certificate authority does not " 1021 "match %s in %s:%lu", CA_MARKER, 1022 host_found->file, host_found->line); 1023 goto fail; 1024 } 1025 if (readonly == ROQUIET) 1026 goto fail; 1027 if (options.check_host_ip && host_ip_differ) { 1028 char *key_msg; 1029 if (ip_status == HOST_NEW) 1030 key_msg = "is unknown"; 1031 else if (ip_status == HOST_OK) 1032 key_msg = "is unchanged"; 1033 else 1034 key_msg = "has a different value"; 1035 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1036 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1037 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1038 error("The %s host key for %s has changed,", type, host); 1039 error("and the key for the corresponding IP address %s", ip); 1040 error("%s. This could either mean that", key_msg); 1041 error("DNS SPOOFING is happening or the IP address for the host"); 1042 error("and its host key have changed at the same time."); 1043 if (ip_status != HOST_NEW) 1044 error("Offending key for IP in %s:%lu", 1045 ip_found->file, ip_found->line); 1046 } 1047 /* The host key has changed. */ 1048 warn_changed_key(host_key); 1049 error("Add correct host key in %.100s to get rid of this message.", 1050 user_hostfiles[0]); 1051 error("Offending %s key in %s:%lu", key_type(host_found->key), 1052 host_found->file, host_found->line); 1053 1054 /* 1055 * If strict host key checking is in use, the user will have 1056 * to edit the key manually and we can only abort. 1057 */ 1058 if (options.strict_host_key_checking) { 1059 error("%s host key for %.200s has changed and you have " 1060 "requested strict checking.", type, host); 1061 goto fail; 1062 } 1063 1064 continue_unsafe: 1065 /* 1066 * If strict host key checking has not been requested, allow 1067 * the connection but without MITM-able authentication or 1068 * forwarding. 1069 */ 1070 if (options.password_authentication) { 1071 error("Password authentication is disabled to avoid " 1072 "man-in-the-middle attacks."); 1073 options.password_authentication = 0; 1074 cancelled_forwarding = 1; 1075 } 1076 if (options.kbd_interactive_authentication) { 1077 error("Keyboard-interactive authentication is disabled" 1078 " to avoid man-in-the-middle attacks."); 1079 options.kbd_interactive_authentication = 0; 1080 options.challenge_response_authentication = 0; 1081 cancelled_forwarding = 1; 1082 } 1083 if (options.challenge_response_authentication) { 1084 error("Challenge/response authentication is disabled" 1085 " to avoid man-in-the-middle attacks."); 1086 options.challenge_response_authentication = 0; 1087 cancelled_forwarding = 1; 1088 } 1089 if (options.forward_agent) { 1090 error("Agent forwarding is disabled to avoid " 1091 "man-in-the-middle attacks."); 1092 options.forward_agent = 0; 1093 cancelled_forwarding = 1; 1094 } 1095 if (options.forward_x11) { 1096 error("X11 forwarding is disabled to avoid " 1097 "man-in-the-middle attacks."); 1098 options.forward_x11 = 0; 1099 cancelled_forwarding = 1; 1100 } 1101 if (options.num_local_forwards > 0 || 1102 options.num_remote_forwards > 0) { 1103 error("Port forwarding is disabled to avoid " 1104 "man-in-the-middle attacks."); 1105 options.num_local_forwards = 1106 options.num_remote_forwards = 0; 1107 cancelled_forwarding = 1; 1108 } 1109 if (options.tun_open != SSH_TUNMODE_NO) { 1110 error("Tunnel forwarding is disabled to avoid " 1111 "man-in-the-middle attacks."); 1112 options.tun_open = SSH_TUNMODE_NO; 1113 cancelled_forwarding = 1; 1114 } 1115 if (options.exit_on_forward_failure && cancelled_forwarding) 1116 fatal("Error: forwarding disabled due to host key " 1117 "check failure"); 1118 1119 /* 1120 * XXX Should permit the user to change to use the new id. 1121 * This could be done by converting the host key to an 1122 * identifying sentence, tell that the host identifies itself 1123 * by that sentence, and ask the user if he/she wishes to 1124 * accept the authentication. 1125 */ 1126 break; 1127 case HOST_FOUND: 1128 fatal("internal error"); 1129 break; 1130 } 1131 1132 if (options.check_host_ip && host_status != HOST_CHANGED && 1133 ip_status == HOST_CHANGED) { 1134 snprintf(msg, sizeof(msg), 1135 "Warning: the %s host key for '%.200s' " 1136 "differs from the key for the IP address '%.128s'" 1137 "\nOffending key for IP in %s:%lu", 1138 type, host, ip, ip_found->file, ip_found->line); 1139 if (host_status == HOST_OK) { 1140 len = strlen(msg); 1141 snprintf(msg + len, sizeof(msg) - len, 1142 "\nMatching host key in %s:%lu", 1143 host_found->file, host_found->line); 1144 } 1145 if (options.strict_host_key_checking == 1) { 1146 logit("%s", msg); 1147 error("Exiting, you have requested strict checking."); 1148 goto fail; 1149 } else if (options.strict_host_key_checking == 2) { 1150 strlcat(msg, "\nAre you sure you want " 1151 "to continue connecting (yes/no)? ", sizeof(msg)); 1152 if (!confirm(msg)) 1153 goto fail; 1154 } else { 1155 logit("%s", msg); 1156 } 1157 } 1158 1159 free(ip); 1160 free(host); 1161 if (host_hostkeys != NULL) 1162 free_hostkeys(host_hostkeys); 1163 if (ip_hostkeys != NULL) 1164 free_hostkeys(ip_hostkeys); 1165 return 0; 1166 1167 fail: 1168 if (want_cert && host_status != HOST_REVOKED) { 1169 /* 1170 * No matching certificate. Downgrade cert to raw key and 1171 * search normally. 1172 */ 1173 debug("No matching CA found. Retry with plain key"); 1174 raw_key = key_from_private(host_key); 1175 if (key_drop_cert(raw_key) != 0) 1176 fatal("Couldn't drop certificate"); 1177 host_key = raw_key; 1178 goto retry; 1179 } 1180 if (raw_key != NULL) 1181 key_free(raw_key); 1182 free(ip); 1183 free(host); 1184 if (host_hostkeys != NULL) 1185 free_hostkeys(host_hostkeys); 1186 if (ip_hostkeys != NULL) 1187 free_hostkeys(ip_hostkeys); 1188 return -1; 1189 } 1190 1191 /* returns 0 if key verifies or -1 if key does NOT verify */ 1192 int 1193 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1194 { 1195 int r = -1, flags = 0; 1196 char *fp; 1197 Key *plain = NULL; 1198 1199 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 1200 debug("Server host key: %s %s", key_type(host_key), fp); 1201 free(fp); 1202 1203 if (key_equal(previous_host_key, host_key)) { 1204 debug("%s: server host key matches cached key", __func__); 1205 return 0; 1206 } 1207 1208 if (options.verify_host_key_dns) { 1209 /* 1210 * XXX certs are not yet supported for DNS, so downgrade 1211 * them and try the plain key. 1212 */ 1213 plain = key_from_private(host_key); 1214 if (key_is_cert(plain)) 1215 key_drop_cert(plain); 1216 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1217 if (flags & DNS_VERIFY_FOUND) { 1218 if (options.verify_host_key_dns == 1 && 1219 flags & DNS_VERIFY_MATCH && 1220 flags & DNS_VERIFY_SECURE) { 1221 key_free(plain); 1222 r = 0; 1223 goto done; 1224 } 1225 if (flags & DNS_VERIFY_MATCH) { 1226 matching_host_key_dns = 1; 1227 } else { 1228 warn_changed_key(plain); 1229 error("Update the SSHFP RR in DNS " 1230 "with the new host key to get rid " 1231 "of this message."); 1232 } 1233 } 1234 } 1235 key_free(plain); 1236 } 1237 1238 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1239 options.user_hostfiles, options.num_user_hostfiles, 1240 options.system_hostfiles, options.num_system_hostfiles); 1241 1242 done: 1243 if (r == 0 && host_key != NULL) { 1244 key_free(previous_host_key); 1245 previous_host_key = key_from_private(host_key); 1246 } 1247 1248 return r; 1249 } 1250 1251 /* 1252 * Starts a dialog with the server, and authenticates the current user on the 1253 * server. This does not need any extra privileges. The basic connection 1254 * to the server must already have been established before this is called. 1255 * If login fails, this function prints an error and never returns. 1256 * This function does not require super-user privileges. 1257 */ 1258 void 1259 ssh_login(Sensitive *sensitive, const char *orighost, 1260 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1261 { 1262 char *host; 1263 char *server_user, *local_user; 1264 1265 local_user = xstrdup(pw->pw_name); 1266 server_user = options.user ? options.user : local_user; 1267 1268 /* Convert the user-supplied hostname into all lowercase. */ 1269 host = xstrdup(orighost); 1270 lowercase(host); 1271 1272 /* Exchange protocol version identification strings with the server. */ 1273 ssh_exchange_identification(timeout_ms); 1274 1275 /* Put the connection into non-blocking mode. */ 1276 packet_set_nonblocking(); 1277 1278 /* key exchange */ 1279 /* authenticate user */ 1280 if (compat20) { 1281 ssh_kex2(host, hostaddr, port); 1282 ssh_userauth2(local_user, server_user, host, sensitive); 1283 } else { 1284 #ifdef WITH_SSH1 1285 ssh_kex(host, hostaddr); 1286 ssh_userauth1(local_user, server_user, host, sensitive); 1287 #else 1288 fatal("ssh1 is not unsupported"); 1289 #endif 1290 } 1291 free(local_user); 1292 } 1293 1294 void 1295 ssh_put_password(char *password) 1296 { 1297 int size; 1298 char *padded; 1299 1300 if (datafellows & SSH_BUG_PASSWORDPAD) { 1301 packet_put_cstring(password); 1302 return; 1303 } 1304 size = roundup(strlen(password) + 1, 32); 1305 padded = xcalloc(1, size); 1306 strlcpy(padded, password, size); 1307 packet_put_string(padded, size); 1308 explicit_bzero(padded, size); 1309 free(padded); 1310 } 1311 1312 /* print all known host keys for a given host, but skip keys of given type */ 1313 static int 1314 show_other_keys(struct hostkeys *hostkeys, Key *key) 1315 { 1316 int type[] = { 1317 KEY_RSA1, 1318 KEY_RSA, 1319 KEY_DSA, 1320 KEY_ECDSA, 1321 KEY_ED25519, 1322 -1 1323 }; 1324 int i, ret = 0; 1325 char *fp, *ra; 1326 const struct hostkey_entry *found; 1327 1328 for (i = 0; type[i] != -1; i++) { 1329 if (type[i] == key->type) 1330 continue; 1331 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1332 continue; 1333 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX); 1334 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART); 1335 logit("WARNING: %s key found for host %s\n" 1336 "in %s:%lu\n" 1337 "%s key fingerprint %s.", 1338 key_type(found->key), 1339 found->host, found->file, found->line, 1340 key_type(found->key), fp); 1341 if (options.visual_host_key) 1342 logit("%s", ra); 1343 free(ra); 1344 free(fp); 1345 ret = 1; 1346 } 1347 return ret; 1348 } 1349 1350 static void 1351 warn_changed_key(Key *host_key) 1352 { 1353 char *fp; 1354 1355 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 1356 1357 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1358 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1359 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1360 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1361 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1362 error("It is also possible that a host key has just been changed."); 1363 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1364 key_type(host_key), fp); 1365 error("Please contact your system administrator."); 1366 1367 free(fp); 1368 } 1369 1370 /* 1371 * Execute a local command 1372 */ 1373 int 1374 ssh_local_cmd(const char *args) 1375 { 1376 char *shell; 1377 pid_t pid; 1378 int status; 1379 void (*osighand)(int); 1380 1381 if (!options.permit_local_command || 1382 args == NULL || !*args) 1383 return (1); 1384 1385 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1386 shell = _PATH_BSHELL; 1387 1388 osighand = signal(SIGCHLD, SIG_DFL); 1389 pid = fork(); 1390 if (pid == 0) { 1391 signal(SIGPIPE, SIG_DFL); 1392 debug3("Executing %s -c \"%s\"", shell, args); 1393 execl(shell, shell, "-c", args, (char *)NULL); 1394 error("Couldn't execute %s -c \"%s\": %s", 1395 shell, args, strerror(errno)); 1396 _exit(1); 1397 } else if (pid == -1) 1398 fatal("fork failed: %.100s", strerror(errno)); 1399 while (waitpid(pid, &status, 0) == -1) 1400 if (errno != EINTR) 1401 fatal("Couldn't wait for child: %s", strerror(errno)); 1402 signal(SIGCHLD, osighand); 1403 1404 if (!WIFEXITED(status)) 1405 return (1); 1406 1407 return (WEXITSTATUS(status)); 1408 } 1409