sshconnect.c revision 294693
1/* $OpenBSD: sshconnect.c,v 1.246 2014/02/06 22:21:01 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: stable/10/crypto/openssh/sshconnect.c 294693 2016-01-24 22:28:18Z des $"); 18 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#include <rpc/rpc.h> 30 31#include <ctype.h> 32#include <errno.h> 33#include <fcntl.h> 34#include <netdb.h> 35#ifdef HAVE_PATHS_H 36#include <paths.h> 37#endif 38#include <pwd.h> 39#include <signal.h> 40#include <stdarg.h> 41#include <stdio.h> 42#include <stdlib.h> 43#include <string.h> 44#include <unistd.h> 45 46#include "xmalloc.h" 47#include "key.h" 48#include "hostfile.h" 49#include "ssh.h" 50#include "rsa.h" 51#include "buffer.h" 52#include "packet.h" 53#include "uidswap.h" 54#include "compat.h" 55#include "key.h" 56#include "sshconnect.h" 57#include "hostfile.h" 58#include "log.h" 59#include "readconf.h" 60#include "atomicio.h" 61#include "misc.h" 62#include "dns.h" 63#include "roaming.h" 64#include "monitor_fdpass.h" 65#include "ssh2.h" 66#include "version.h" 67 68char *client_version_string = NULL; 69char *server_version_string = NULL; 70 71static int matching_host_key_dns = 0; 72 73static pid_t proxy_command_pid = 0; 74 75/* import */ 76extern Options options; 77extern char *__progname; 78extern uid_t original_real_uid; 79extern uid_t original_effective_uid; 80 81static int show_other_keys(struct hostkeys *, Key *); 82static void warn_changed_key(Key *); 83 84/* Expand a proxy command */ 85static char * 86expand_proxy_command(const char *proxy_command, const char *user, 87 const char *host, int port) 88{ 89 char *tmp, *ret, strport[NI_MAXSERV]; 90 91 snprintf(strport, sizeof strport, "%d", port); 92 xasprintf(&tmp, "exec %s", proxy_command); 93 ret = percent_expand(tmp, "h", host, "p", strport, 94 "r", options.user, (char *)NULL); 95 free(tmp); 96 return ret; 97} 98 99/* 100 * Connect to the given ssh server using a proxy command that passes a 101 * a connected fd back to us. 102 */ 103static int 104ssh_proxy_fdpass_connect(const char *host, u_short port, 105 const char *proxy_command) 106{ 107 char *command_string; 108 int sp[2], sock; 109 pid_t pid; 110 char *shell; 111 112 if ((shell = getenv("SHELL")) == NULL) 113 shell = _PATH_BSHELL; 114 115 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 116 fatal("Could not create socketpair to communicate with " 117 "proxy dialer: %.100s", strerror(errno)); 118 119 command_string = expand_proxy_command(proxy_command, options.user, 120 host, port); 121 debug("Executing proxy dialer command: %.500s", command_string); 122 123 /* Fork and execute the proxy command. */ 124 if ((pid = fork()) == 0) { 125 char *argv[10]; 126 127 /* Child. Permanently give up superuser privileges. */ 128 permanently_drop_suid(original_real_uid); 129 130 close(sp[1]); 131 /* Redirect stdin and stdout. */ 132 if (sp[0] != 0) { 133 if (dup2(sp[0], 0) < 0) 134 perror("dup2 stdin"); 135 } 136 if (sp[0] != 1) { 137 if (dup2(sp[0], 1) < 0) 138 perror("dup2 stdout"); 139 } 140 if (sp[0] >= 2) 141 close(sp[0]); 142 143 /* 144 * Stderr is left as it is so that error messages get 145 * printed on the user's terminal. 146 */ 147 argv[0] = shell; 148 argv[1] = "-c"; 149 argv[2] = command_string; 150 argv[3] = NULL; 151 152 /* 153 * Execute the proxy command. 154 * Note that we gave up any extra privileges above. 155 */ 156 execv(argv[0], argv); 157 perror(argv[0]); 158 exit(1); 159 } 160 /* Parent. */ 161 if (pid < 0) 162 fatal("fork failed: %.100s", strerror(errno)); 163 close(sp[0]); 164 free(command_string); 165 166 if ((sock = mm_receive_fd(sp[1])) == -1) 167 fatal("proxy dialer did not pass back a connection"); 168 169 while (waitpid(pid, NULL, 0) == -1) 170 if (errno != EINTR) 171 fatal("Couldn't wait for child: %s", strerror(errno)); 172 173 /* Set the connection file descriptors. */ 174 packet_set_connection(sock, sock); 175 176 return 0; 177} 178 179/* 180 * Connect to the given ssh server using a proxy command. 181 */ 182static int 183ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 184{ 185 char *command_string; 186 int pin[2], pout[2]; 187 pid_t pid; 188 char *shell; 189 190 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 191 shell = _PATH_BSHELL; 192 193 /* Create pipes for communicating with the proxy. */ 194 if (pipe(pin) < 0 || pipe(pout) < 0) 195 fatal("Could not create pipes to communicate with the proxy: %.100s", 196 strerror(errno)); 197 198 command_string = expand_proxy_command(proxy_command, options.user, 199 host, port); 200 debug("Executing proxy command: %.500s", command_string); 201 202 /* Fork and execute the proxy command. */ 203 if ((pid = fork()) == 0) { 204 char *argv[10]; 205 206 /* Child. Permanently give up superuser privileges. */ 207 permanently_drop_suid(original_real_uid); 208 209 /* Redirect stdin and stdout. */ 210 close(pin[1]); 211 if (pin[0] != 0) { 212 if (dup2(pin[0], 0) < 0) 213 perror("dup2 stdin"); 214 close(pin[0]); 215 } 216 close(pout[0]); 217 if (dup2(pout[1], 1) < 0) 218 perror("dup2 stdout"); 219 /* Cannot be 1 because pin allocated two descriptors. */ 220 close(pout[1]); 221 222 /* Stderr is left as it is so that error messages get 223 printed on the user's terminal. */ 224 argv[0] = shell; 225 argv[1] = "-c"; 226 argv[2] = command_string; 227 argv[3] = NULL; 228 229 /* Execute the proxy command. Note that we gave up any 230 extra privileges above. */ 231 signal(SIGPIPE, SIG_DFL); 232 execv(argv[0], argv); 233 perror(argv[0]); 234 exit(1); 235 } 236 /* Parent. */ 237 if (pid < 0) 238 fatal("fork failed: %.100s", strerror(errno)); 239 else 240 proxy_command_pid = pid; /* save pid to clean up later */ 241 242 /* Close child side of the descriptors. */ 243 close(pin[0]); 244 close(pout[1]); 245 246 /* Free the command name. */ 247 free(command_string); 248 249 /* Set the connection file descriptors. */ 250 packet_set_connection(pout[0], pin[1]); 251 252 /* Indicate OK return */ 253 return 0; 254} 255 256void 257ssh_kill_proxy_command(void) 258{ 259 /* 260 * Send SIGHUP to proxy command if used. We don't wait() in 261 * case it hangs and instead rely on init to reap the child 262 */ 263 if (proxy_command_pid > 1) 264 kill(proxy_command_pid, SIGHUP); 265} 266 267/* 268 * Creates a (possibly privileged) socket for use as the ssh connection. 269 */ 270static int 271ssh_create_socket(int privileged, struct addrinfo *ai) 272{ 273 int sock, r, gaierr; 274 struct addrinfo hints, *res = NULL; 275 276 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 277 if (sock < 0) { 278 error("socket: %s", strerror(errno)); 279 return -1; 280 } 281 fcntl(sock, F_SETFD, FD_CLOEXEC); 282 283 /* Bind the socket to an alternative local IP address */ 284 if (options.bind_address == NULL && !privileged) 285 return sock; 286 287 if (options.bind_address) { 288 memset(&hints, 0, sizeof(hints)); 289 hints.ai_family = ai->ai_family; 290 hints.ai_socktype = ai->ai_socktype; 291 hints.ai_protocol = ai->ai_protocol; 292 hints.ai_flags = AI_PASSIVE; 293 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 294 if (gaierr) { 295 error("getaddrinfo: %s: %s", options.bind_address, 296 ssh_gai_strerror(gaierr)); 297 close(sock); 298 return -1; 299 } 300 } 301 /* 302 * If we are running as root and want to connect to a privileged 303 * port, bind our own socket to a privileged port. 304 */ 305 if (privileged) { 306 PRIV_START; 307 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 308 PRIV_END; 309 if (r < 0) { 310 error("bindresvport_sa: af=%d %s", ai->ai_family, 311 strerror(errno)); 312 goto fail; 313 } 314 } else { 315 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 316 error("bind: %s: %s", options.bind_address, 317 strerror(errno)); 318 fail: 319 close(sock); 320 freeaddrinfo(res); 321 return -1; 322 } 323 } 324 if (res != NULL) 325 freeaddrinfo(res); 326 return sock; 327} 328 329static int 330timeout_connect(int sockfd, const struct sockaddr *serv_addr, 331 socklen_t addrlen, int *timeoutp) 332{ 333 fd_set *fdset; 334 struct timeval tv, t_start; 335 socklen_t optlen; 336 int optval, rc, result = -1; 337 338 gettimeofday(&t_start, NULL); 339 340 if (*timeoutp <= 0) { 341 result = connect(sockfd, serv_addr, addrlen); 342 goto done; 343 } 344 345 set_nonblock(sockfd); 346 rc = connect(sockfd, serv_addr, addrlen); 347 if (rc == 0) { 348 unset_nonblock(sockfd); 349 result = 0; 350 goto done; 351 } 352 if (errno != EINPROGRESS) { 353 result = -1; 354 goto done; 355 } 356 357 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), 358 sizeof(fd_mask)); 359 FD_SET(sockfd, fdset); 360 ms_to_timeval(&tv, *timeoutp); 361 362 for (;;) { 363 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 364 if (rc != -1 || errno != EINTR) 365 break; 366 } 367 368 switch (rc) { 369 case 0: 370 /* Timed out */ 371 errno = ETIMEDOUT; 372 break; 373 case -1: 374 /* Select error */ 375 debug("select: %s", strerror(errno)); 376 break; 377 case 1: 378 /* Completed or failed */ 379 optval = 0; 380 optlen = sizeof(optval); 381 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 382 &optlen) == -1) { 383 debug("getsockopt: %s", strerror(errno)); 384 break; 385 } 386 if (optval != 0) { 387 errno = optval; 388 break; 389 } 390 result = 0; 391 unset_nonblock(sockfd); 392 break; 393 default: 394 /* Should not occur */ 395 fatal("Bogus return (%d) from select()", rc); 396 } 397 398 free(fdset); 399 400 done: 401 if (result == 0 && *timeoutp > 0) { 402 ms_subtract_diff(&t_start, timeoutp); 403 if (*timeoutp <= 0) { 404 errno = ETIMEDOUT; 405 result = -1; 406 } 407 } 408 409 return (result); 410} 411 412/* 413 * Opens a TCP/IP connection to the remote server on the given host. 414 * The address of the remote host will be returned in hostaddr. 415 * If port is 0, the default port will be used. If needpriv is true, 416 * a privileged port will be allocated to make the connection. 417 * This requires super-user privileges if needpriv is true. 418 * Connection_attempts specifies the maximum number of tries (one per 419 * second). If proxy_command is non-NULL, it specifies the command (with %h 420 * and %p substituted for host and port, respectively) to use to contact 421 * the daemon. 422 */ 423static int 424ssh_connect_direct(const char *host, struct addrinfo *aitop, 425 struct sockaddr_storage *hostaddr, u_short port, int family, 426 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 427{ 428 int on = 1; 429 int sock = -1, attempt; 430 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 431 struct addrinfo *ai; 432 433 debug2("ssh_connect: needpriv %d", needpriv); 434 435 for (attempt = 0; attempt < connection_attempts; attempt++) { 436 if (attempt > 0) { 437 /* Sleep a moment before retrying. */ 438 sleep(1); 439 debug("Trying again..."); 440 } 441 /* 442 * Loop through addresses for this host, and try each one in 443 * sequence until the connection succeeds. 444 */ 445 for (ai = aitop; ai; ai = ai->ai_next) { 446 if (ai->ai_family != AF_INET && 447 ai->ai_family != AF_INET6) 448 continue; 449 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 450 ntop, sizeof(ntop), strport, sizeof(strport), 451 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 452 error("ssh_connect: getnameinfo failed"); 453 continue; 454 } 455 debug("Connecting to %.200s [%.100s] port %s.", 456 host, ntop, strport); 457 458 /* Create a socket for connecting. */ 459 sock = ssh_create_socket(needpriv, ai); 460 if (sock < 0) 461 /* Any error is already output */ 462 continue; 463 464 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 465 timeout_ms) >= 0) { 466 /* Successful connection. */ 467 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 468 break; 469 } else { 470 debug("connect to address %s port %s: %s", 471 ntop, strport, strerror(errno)); 472 close(sock); 473 sock = -1; 474 } 475 } 476 if (sock != -1) 477 break; /* Successful connection. */ 478 } 479 480 /* Return failure if we didn't get a successful connection. */ 481 if (sock == -1) { 482 error("ssh: connect to host %s port %s: %s", 483 host, strport, strerror(errno)); 484 return (-1); 485 } 486 487 debug("Connection established."); 488 489 /* Set SO_KEEPALIVE if requested. */ 490 if (want_keepalive && 491 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 492 sizeof(on)) < 0) 493 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 494 495 /* Set the connection. */ 496 packet_set_connection(sock, sock); 497 498 return 0; 499} 500 501int 502ssh_connect(const char *host, struct addrinfo *addrs, 503 struct sockaddr_storage *hostaddr, u_short port, int family, 504 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 505{ 506 if (options.proxy_command == NULL) { 507 return ssh_connect_direct(host, addrs, hostaddr, port, family, 508 connection_attempts, timeout_ms, want_keepalive, needpriv); 509 } else if (strcmp(options.proxy_command, "-") == 0) { 510 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 511 return 0; /* Always succeeds */ 512 } else if (options.proxy_use_fdpass) { 513 return ssh_proxy_fdpass_connect(host, port, 514 options.proxy_command); 515 } 516 return ssh_proxy_connect(host, port, options.proxy_command); 517} 518 519static void 520send_client_banner(int connection_out, int minor1) 521{ 522 /* Send our own protocol version identification. */ 523 xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s%s", 524 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 525 compat20 ? PROTOCOL_MINOR_2 : minor1, 526 SSH_VERSION, 527 *options.version_addendum == '\0' ? "" : " ", 528 options.version_addendum, compat20 ? "\r\n" : "\n"); 529 if (roaming_atomicio(vwrite, connection_out, client_version_string, 530 strlen(client_version_string)) != strlen(client_version_string)) 531 fatal("write: %.100s", strerror(errno)); 532 chop(client_version_string); 533 debug("Local version string %.100s", client_version_string); 534} 535 536/* 537 * Waits for the server identification string, and sends our own 538 * identification string. 539 */ 540void 541ssh_exchange_identification(int timeout_ms) 542{ 543 char buf[256], remote_version[256]; /* must be same size! */ 544 int remote_major, remote_minor, mismatch; 545 int connection_in = packet_get_connection_in(); 546 int connection_out = packet_get_connection_out(); 547 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 548 u_int i, n; 549 size_t len; 550 int fdsetsz, remaining, rc; 551 struct timeval t_start, t_remaining; 552 fd_set *fdset; 553 554 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 555 fdset = xcalloc(1, fdsetsz); 556 557 /* 558 * If we are SSH2-only then we can send the banner immediately and 559 * save a round-trip. 560 */ 561 if (options.protocol == SSH_PROTO_2) { 562 enable_compat20(); 563 send_client_banner(connection_out, 0); 564 client_banner_sent = 1; 565 } 566 567 /* Read other side's version identification. */ 568 remaining = timeout_ms; 569 for (n = 0;;) { 570 for (i = 0; i < sizeof(buf) - 1; i++) { 571 if (timeout_ms > 0) { 572 gettimeofday(&t_start, NULL); 573 ms_to_timeval(&t_remaining, remaining); 574 FD_SET(connection_in, fdset); 575 rc = select(connection_in + 1, fdset, NULL, 576 fdset, &t_remaining); 577 ms_subtract_diff(&t_start, &remaining); 578 if (rc == 0 || remaining <= 0) 579 fatal("Connection timed out during " 580 "banner exchange"); 581 if (rc == -1) { 582 if (errno == EINTR) 583 continue; 584 fatal("ssh_exchange_identification: " 585 "select: %s", strerror(errno)); 586 } 587 } 588 589 len = roaming_atomicio(read, connection_in, &buf[i], 1); 590 591 if (len != 1 && errno == EPIPE) 592 fatal("ssh_exchange_identification: " 593 "Connection closed by remote host"); 594 else if (len != 1) 595 fatal("ssh_exchange_identification: " 596 "read: %.100s", strerror(errno)); 597 if (buf[i] == '\r') { 598 buf[i] = '\n'; 599 buf[i + 1] = 0; 600 continue; /**XXX wait for \n */ 601 } 602 if (buf[i] == '\n') { 603 buf[i + 1] = 0; 604 break; 605 } 606 if (++n > 65536) 607 fatal("ssh_exchange_identification: " 608 "No banner received"); 609 } 610 buf[sizeof(buf) - 1] = 0; 611 if (strncmp(buf, "SSH-", 4) == 0) 612 break; 613 debug("ssh_exchange_identification: %s", buf); 614 } 615 server_version_string = xstrdup(buf); 616 free(fdset); 617 618 /* 619 * Check that the versions match. In future this might accept 620 * several versions and set appropriate flags to handle them. 621 */ 622 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 623 &remote_major, &remote_minor, remote_version) != 3) 624 fatal("Bad remote protocol version identification: '%.100s'", buf); 625 debug("Remote protocol version %d.%d, remote software version %.100s", 626 remote_major, remote_minor, remote_version); 627 628 compat_datafellows(remote_version); 629 mismatch = 0; 630 631 switch (remote_major) { 632 case 1: 633 if (remote_minor == 99 && 634 (options.protocol & SSH_PROTO_2) && 635 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 636 enable_compat20(); 637 break; 638 } 639 if (!(options.protocol & SSH_PROTO_1)) { 640 mismatch = 1; 641 break; 642 } 643 if (remote_minor < 3) { 644 fatal("Remote machine has too old SSH software version."); 645 } else if (remote_minor == 3 || remote_minor == 4) { 646 /* We speak 1.3, too. */ 647 enable_compat13(); 648 minor1 = 3; 649 if (options.forward_agent) { 650 logit("Agent forwarding disabled for protocol 1.3"); 651 options.forward_agent = 0; 652 } 653 } 654 break; 655 case 2: 656 if (options.protocol & SSH_PROTO_2) { 657 enable_compat20(); 658 break; 659 } 660 /* FALLTHROUGH */ 661 default: 662 mismatch = 1; 663 break; 664 } 665 if (mismatch) 666 fatal("Protocol major versions differ: %d vs. %d", 667 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 668 remote_major); 669 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 670 fatal("Server version \"%.100s\" uses unsafe key agreement; " 671 "refusing connection", remote_version); 672 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 673 logit("Server version \"%.100s\" uses unsafe RSA signature " 674 "scheme; disabling use of RSA keys", remote_version); 675 if (!client_banner_sent) 676 send_client_banner(connection_out, minor1); 677 chop(server_version_string); 678} 679 680/* defaults to 'no' */ 681static int 682confirm(const char *prompt) 683{ 684 const char *msg, *again = "Please type 'yes' or 'no': "; 685 char *p; 686 int ret = -1; 687 688 if (options.batch_mode) 689 return 0; 690 for (msg = prompt;;msg = again) { 691 p = read_passphrase(msg, RP_ECHO); 692 if (p == NULL || 693 (p[0] == '\0') || (p[0] == '\n') || 694 strncasecmp(p, "no", 2) == 0) 695 ret = 0; 696 if (p && strncasecmp(p, "yes", 3) == 0) 697 ret = 1; 698 free(p); 699 if (ret != -1) 700 return ret; 701 } 702} 703 704static int 705check_host_cert(const char *host, const Key *host_key) 706{ 707 const char *reason; 708 709 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 710 error("%s", reason); 711 return 0; 712 } 713 if (buffer_len(&host_key->cert->critical) != 0) { 714 error("Certificate for %s contains unsupported " 715 "critical options(s)", host); 716 return 0; 717 } 718 return 1; 719} 720 721static int 722sockaddr_is_local(struct sockaddr *hostaddr) 723{ 724 switch (hostaddr->sa_family) { 725 case AF_INET: 726 return (ntohl(((struct sockaddr_in *)hostaddr)-> 727 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 728 case AF_INET6: 729 return IN6_IS_ADDR_LOOPBACK( 730 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 731 default: 732 return 0; 733 } 734} 735 736/* 737 * Prepare the hostname and ip address strings that are used to lookup 738 * host keys in known_hosts files. These may have a port number appended. 739 */ 740void 741get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 742 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 743{ 744 char ntop[NI_MAXHOST]; 745 socklen_t addrlen; 746 747 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 748 case -1: 749 addrlen = 0; 750 break; 751 case AF_INET: 752 addrlen = sizeof(struct sockaddr_in); 753 break; 754 case AF_INET6: 755 addrlen = sizeof(struct sockaddr_in6); 756 break; 757 default: 758 addrlen = sizeof(struct sockaddr); 759 break; 760 } 761 762 /* 763 * We don't have the remote ip-address for connections 764 * using a proxy command 765 */ 766 if (hostfile_ipaddr != NULL) { 767 if (options.proxy_command == NULL) { 768 if (getnameinfo(hostaddr, addrlen, 769 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 770 fatal("check_host_key: getnameinfo failed"); 771 *hostfile_ipaddr = put_host_port(ntop, port); 772 } else { 773 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 774 "command>"); 775 } 776 } 777 778 /* 779 * Allow the user to record the key under a different name or 780 * differentiate a non-standard port. This is useful for ssh 781 * tunneling over forwarded connections or if you run multiple 782 * sshd's on different ports on the same machine. 783 */ 784 if (hostfile_hostname != NULL) { 785 if (options.host_key_alias != NULL) { 786 *hostfile_hostname = xstrdup(options.host_key_alias); 787 debug("using hostkeyalias: %s", *hostfile_hostname); 788 } else { 789 *hostfile_hostname = put_host_port(hostname, port); 790 } 791 } 792} 793 794/* 795 * check whether the supplied host key is valid, return -1 if the key 796 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 797 */ 798#define RDRW 0 799#define RDONLY 1 800#define ROQUIET 2 801static int 802check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 803 Key *host_key, int readonly, 804 char **user_hostfiles, u_int num_user_hostfiles, 805 char **system_hostfiles, u_int num_system_hostfiles) 806{ 807 HostStatus host_status; 808 HostStatus ip_status; 809 Key *raw_key = NULL; 810 char *ip = NULL, *host = NULL; 811 char hostline[1000], *hostp, *fp, *ra; 812 char msg[1024]; 813 const char *type; 814 const struct hostkey_entry *host_found, *ip_found; 815 int len, cancelled_forwarding = 0; 816 int local = sockaddr_is_local(hostaddr); 817 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 818 struct hostkeys *host_hostkeys, *ip_hostkeys; 819 u_int i; 820 821 /* 822 * Force accepting of the host key for loopback/localhost. The 823 * problem is that if the home directory is NFS-mounted to multiple 824 * machines, localhost will refer to a different machine in each of 825 * them, and the user will get bogus HOST_CHANGED warnings. This 826 * essentially disables host authentication for localhost; however, 827 * this is probably not a real problem. 828 */ 829 if (options.no_host_authentication_for_localhost == 1 && local && 830 options.host_key_alias == NULL) { 831 debug("Forcing accepting of host key for " 832 "loopback/localhost."); 833 return 0; 834 } 835 836 /* 837 * Prepare the hostname and address strings used for hostkey lookup. 838 * In some cases, these will have a port number appended. 839 */ 840 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 841 842 /* 843 * Turn off check_host_ip if the connection is to localhost, via proxy 844 * command or if we don't have a hostname to compare with 845 */ 846 if (options.check_host_ip && (local || 847 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 848 options.check_host_ip = 0; 849 850 host_hostkeys = init_hostkeys(); 851 for (i = 0; i < num_user_hostfiles; i++) 852 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 853 for (i = 0; i < num_system_hostfiles; i++) 854 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 855 856 ip_hostkeys = NULL; 857 if (!want_cert && options.check_host_ip) { 858 ip_hostkeys = init_hostkeys(); 859 for (i = 0; i < num_user_hostfiles; i++) 860 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 861 for (i = 0; i < num_system_hostfiles; i++) 862 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 863 } 864 865 retry: 866 /* Reload these as they may have changed on cert->key downgrade */ 867 want_cert = key_is_cert(host_key); 868 type = key_type(host_key); 869 870 /* 871 * Check if the host key is present in the user's list of known 872 * hosts or in the systemwide list. 873 */ 874 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 875 &host_found); 876 877 /* 878 * Also perform check for the ip address, skip the check if we are 879 * localhost, looking for a certificate, or the hostname was an ip 880 * address to begin with. 881 */ 882 if (!want_cert && ip_hostkeys != NULL) { 883 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 884 &ip_found); 885 if (host_status == HOST_CHANGED && 886 (ip_status != HOST_CHANGED || 887 (ip_found != NULL && 888 !key_equal(ip_found->key, host_found->key)))) 889 host_ip_differ = 1; 890 } else 891 ip_status = host_status; 892 893 switch (host_status) { 894 case HOST_OK: 895 /* The host is known and the key matches. */ 896 debug("Host '%.200s' is known and matches the %s host %s.", 897 host, type, want_cert ? "certificate" : "key"); 898 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 899 host_found->file, host_found->line); 900 if (want_cert && !check_host_cert(hostname, host_key)) 901 goto fail; 902 if (options.check_host_ip && ip_status == HOST_NEW) { 903 if (readonly || want_cert) 904 logit("%s host key for IP address " 905 "'%.128s' not in list of known hosts.", 906 type, ip); 907 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 908 host_key, options.hash_known_hosts)) 909 logit("Failed to add the %s host key for IP " 910 "address '%.128s' to the list of known " 911 "hosts (%.30s).", type, ip, 912 user_hostfiles[0]); 913 else 914 logit("Warning: Permanently added the %s host " 915 "key for IP address '%.128s' to the list " 916 "of known hosts.", type, ip); 917 } else if (options.visual_host_key) { 918 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 919 ra = key_fingerprint(host_key, SSH_FP_MD5, 920 SSH_FP_RANDOMART); 921 logit("Host key fingerprint is %s\n%s\n", fp, ra); 922 free(ra); 923 free(fp); 924 } 925 break; 926 case HOST_NEW: 927 if (options.host_key_alias == NULL && port != 0 && 928 port != SSH_DEFAULT_PORT) { 929 debug("checking without port identifier"); 930 if (check_host_key(hostname, hostaddr, 0, host_key, 931 ROQUIET, user_hostfiles, num_user_hostfiles, 932 system_hostfiles, num_system_hostfiles) == 0) { 933 debug("found matching key w/out port"); 934 break; 935 } 936 } 937 if (readonly || want_cert) 938 goto fail; 939 /* The host is new. */ 940 if (options.strict_host_key_checking == 1) { 941 /* 942 * User has requested strict host key checking. We 943 * will not add the host key automatically. The only 944 * alternative left is to abort. 945 */ 946 error("No %s host key is known for %.200s and you " 947 "have requested strict checking.", type, host); 948 goto fail; 949 } else if (options.strict_host_key_checking == 2) { 950 char msg1[1024], msg2[1024]; 951 952 if (show_other_keys(host_hostkeys, host_key)) 953 snprintf(msg1, sizeof(msg1), 954 "\nbut keys of different type are already" 955 " known for this host."); 956 else 957 snprintf(msg1, sizeof(msg1), "."); 958 /* The default */ 959 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 960 ra = key_fingerprint(host_key, SSH_FP_MD5, 961 SSH_FP_RANDOMART); 962 msg2[0] = '\0'; 963 if (options.verify_host_key_dns) { 964 if (matching_host_key_dns) 965 snprintf(msg2, sizeof(msg2), 966 "Matching host key fingerprint" 967 " found in DNS.\n"); 968 else 969 snprintf(msg2, sizeof(msg2), 970 "No matching host key fingerprint" 971 " found in DNS.\n"); 972 } 973 snprintf(msg, sizeof(msg), 974 "The authenticity of host '%.200s (%s)' can't be " 975 "established%s\n" 976 "%s key fingerprint is %s.%s%s\n%s" 977 "Are you sure you want to continue connecting " 978 "(yes/no)? ", 979 host, ip, msg1, type, fp, 980 options.visual_host_key ? "\n" : "", 981 options.visual_host_key ? ra : "", 982 msg2); 983 free(ra); 984 free(fp); 985 if (!confirm(msg)) 986 goto fail; 987 } 988 /* 989 * If not in strict mode, add the key automatically to the 990 * local known_hosts file. 991 */ 992 if (options.check_host_ip && ip_status == HOST_NEW) { 993 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 994 hostp = hostline; 995 if (options.hash_known_hosts) { 996 /* Add hash of host and IP separately */ 997 r = add_host_to_hostfile(user_hostfiles[0], 998 host, host_key, options.hash_known_hosts) && 999 add_host_to_hostfile(user_hostfiles[0], ip, 1000 host_key, options.hash_known_hosts); 1001 } else { 1002 /* Add unhashed "host,ip" */ 1003 r = add_host_to_hostfile(user_hostfiles[0], 1004 hostline, host_key, 1005 options.hash_known_hosts); 1006 } 1007 } else { 1008 r = add_host_to_hostfile(user_hostfiles[0], host, 1009 host_key, options.hash_known_hosts); 1010 hostp = host; 1011 } 1012 1013 if (!r) 1014 logit("Failed to add the host to the list of known " 1015 "hosts (%.500s).", user_hostfiles[0]); 1016 else 1017 logit("Warning: Permanently added '%.200s' (%s) to the " 1018 "list of known hosts.", hostp, type); 1019 break; 1020 case HOST_REVOKED: 1021 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1022 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1023 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1024 error("The %s host key for %s is marked as revoked.", type, host); 1025 error("This could mean that a stolen key is being used to"); 1026 error("impersonate this host."); 1027 1028 /* 1029 * If strict host key checking is in use, the user will have 1030 * to edit the key manually and we can only abort. 1031 */ 1032 if (options.strict_host_key_checking) { 1033 error("%s host key for %.200s was revoked and you have " 1034 "requested strict checking.", type, host); 1035 goto fail; 1036 } 1037 goto continue_unsafe; 1038 1039 case HOST_CHANGED: 1040 if (want_cert) { 1041 /* 1042 * This is only a debug() since it is valid to have 1043 * CAs with wildcard DNS matches that don't match 1044 * all hosts that one might visit. 1045 */ 1046 debug("Host certificate authority does not " 1047 "match %s in %s:%lu", CA_MARKER, 1048 host_found->file, host_found->line); 1049 goto fail; 1050 } 1051 if (readonly == ROQUIET) 1052 goto fail; 1053 if (options.check_host_ip && host_ip_differ) { 1054 char *key_msg; 1055 if (ip_status == HOST_NEW) 1056 key_msg = "is unknown"; 1057 else if (ip_status == HOST_OK) 1058 key_msg = "is unchanged"; 1059 else 1060 key_msg = "has a different value"; 1061 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1062 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1063 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1064 error("The %s host key for %s has changed,", type, host); 1065 error("and the key for the corresponding IP address %s", ip); 1066 error("%s. This could either mean that", key_msg); 1067 error("DNS SPOOFING is happening or the IP address for the host"); 1068 error("and its host key have changed at the same time."); 1069 if (ip_status != HOST_NEW) 1070 error("Offending key for IP in %s:%lu", 1071 ip_found->file, ip_found->line); 1072 } 1073 /* The host key has changed. */ 1074 warn_changed_key(host_key); 1075 error("Add correct host key in %.100s to get rid of this message.", 1076 user_hostfiles[0]); 1077 error("Offending %s key in %s:%lu", key_type(host_found->key), 1078 host_found->file, host_found->line); 1079 1080 /* 1081 * If strict host key checking is in use, the user will have 1082 * to edit the key manually and we can only abort. 1083 */ 1084 if (options.strict_host_key_checking) { 1085 error("%s host key for %.200s has changed and you have " 1086 "requested strict checking.", type, host); 1087 goto fail; 1088 } 1089 1090 continue_unsafe: 1091 /* 1092 * If strict host key checking has not been requested, allow 1093 * the connection but without MITM-able authentication or 1094 * forwarding. 1095 */ 1096 if (options.password_authentication) { 1097 error("Password authentication is disabled to avoid " 1098 "man-in-the-middle attacks."); 1099 options.password_authentication = 0; 1100 cancelled_forwarding = 1; 1101 } 1102 if (options.kbd_interactive_authentication) { 1103 error("Keyboard-interactive authentication is disabled" 1104 " to avoid man-in-the-middle attacks."); 1105 options.kbd_interactive_authentication = 0; 1106 options.challenge_response_authentication = 0; 1107 cancelled_forwarding = 1; 1108 } 1109 if (options.challenge_response_authentication) { 1110 error("Challenge/response authentication is disabled" 1111 " to avoid man-in-the-middle attacks."); 1112 options.challenge_response_authentication = 0; 1113 cancelled_forwarding = 1; 1114 } 1115 if (options.forward_agent) { 1116 error("Agent forwarding is disabled to avoid " 1117 "man-in-the-middle attacks."); 1118 options.forward_agent = 0; 1119 cancelled_forwarding = 1; 1120 } 1121 if (options.forward_x11) { 1122 error("X11 forwarding is disabled to avoid " 1123 "man-in-the-middle attacks."); 1124 options.forward_x11 = 0; 1125 cancelled_forwarding = 1; 1126 } 1127 if (options.num_local_forwards > 0 || 1128 options.num_remote_forwards > 0) { 1129 error("Port forwarding is disabled to avoid " 1130 "man-in-the-middle attacks."); 1131 options.num_local_forwards = 1132 options.num_remote_forwards = 0; 1133 cancelled_forwarding = 1; 1134 } 1135 if (options.tun_open != SSH_TUNMODE_NO) { 1136 error("Tunnel forwarding is disabled to avoid " 1137 "man-in-the-middle attacks."); 1138 options.tun_open = SSH_TUNMODE_NO; 1139 cancelled_forwarding = 1; 1140 } 1141 if (options.exit_on_forward_failure && cancelled_forwarding) 1142 fatal("Error: forwarding disabled due to host key " 1143 "check failure"); 1144 1145 /* 1146 * XXX Should permit the user to change to use the new id. 1147 * This could be done by converting the host key to an 1148 * identifying sentence, tell that the host identifies itself 1149 * by that sentence, and ask the user if he/she wishes to 1150 * accept the authentication. 1151 */ 1152 break; 1153 case HOST_FOUND: 1154 fatal("internal error"); 1155 break; 1156 } 1157 1158 if (options.check_host_ip && host_status != HOST_CHANGED && 1159 ip_status == HOST_CHANGED) { 1160 snprintf(msg, sizeof(msg), 1161 "Warning: the %s host key for '%.200s' " 1162 "differs from the key for the IP address '%.128s'" 1163 "\nOffending key for IP in %s:%lu", 1164 type, host, ip, ip_found->file, ip_found->line); 1165 if (host_status == HOST_OK) { 1166 len = strlen(msg); 1167 snprintf(msg + len, sizeof(msg) - len, 1168 "\nMatching host key in %s:%lu", 1169 host_found->file, host_found->line); 1170 } 1171 if (options.strict_host_key_checking == 1) { 1172 logit("%s", msg); 1173 error("Exiting, you have requested strict checking."); 1174 goto fail; 1175 } else if (options.strict_host_key_checking == 2) { 1176 strlcat(msg, "\nAre you sure you want " 1177 "to continue connecting (yes/no)? ", sizeof(msg)); 1178 if (!confirm(msg)) 1179 goto fail; 1180 } else { 1181 logit("%s", msg); 1182 } 1183 } 1184 1185 free(ip); 1186 free(host); 1187 if (host_hostkeys != NULL) 1188 free_hostkeys(host_hostkeys); 1189 if (ip_hostkeys != NULL) 1190 free_hostkeys(ip_hostkeys); 1191 return 0; 1192 1193fail: 1194 if (want_cert && host_status != HOST_REVOKED) { 1195 /* 1196 * No matching certificate. Downgrade cert to raw key and 1197 * search normally. 1198 */ 1199 debug("No matching CA found. Retry with plain key"); 1200 raw_key = key_from_private(host_key); 1201 if (key_drop_cert(raw_key) != 0) 1202 fatal("Couldn't drop certificate"); 1203 host_key = raw_key; 1204 goto retry; 1205 } 1206 if (raw_key != NULL) 1207 key_free(raw_key); 1208 free(ip); 1209 free(host); 1210 if (host_hostkeys != NULL) 1211 free_hostkeys(host_hostkeys); 1212 if (ip_hostkeys != NULL) 1213 free_hostkeys(ip_hostkeys); 1214 return -1; 1215} 1216 1217/* returns 0 if key verifies or -1 if key does NOT verify */ 1218int 1219verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1220{ 1221 int flags = 0; 1222 char *fp; 1223 Key *plain = NULL; 1224 1225 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 1226 debug("Server host key: %s %s", key_type(host_key), fp); 1227 free(fp); 1228 1229 if (options.verify_host_key_dns) { 1230 /* 1231 * XXX certs are not yet supported for DNS, so downgrade 1232 * them and try the plain key. 1233 */ 1234 plain = key_from_private(host_key); 1235 if (key_is_cert(plain)) 1236 key_drop_cert(plain); 1237 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1238 if (flags & DNS_VERIFY_FOUND) { 1239 if (options.verify_host_key_dns == 1 && 1240 flags & DNS_VERIFY_MATCH && 1241 flags & DNS_VERIFY_SECURE) { 1242 key_free(plain); 1243 return 0; 1244 } 1245 if (flags & DNS_VERIFY_MATCH) { 1246 matching_host_key_dns = 1; 1247 } else { 1248 warn_changed_key(plain); 1249 error("Update the SSHFP RR in DNS " 1250 "with the new host key to get rid " 1251 "of this message."); 1252 } 1253 } 1254 } 1255 key_free(plain); 1256 } 1257 1258 return check_host_key(host, hostaddr, options.port, host_key, RDRW, 1259 options.user_hostfiles, options.num_user_hostfiles, 1260 options.system_hostfiles, options.num_system_hostfiles); 1261} 1262 1263/* 1264 * Starts a dialog with the server, and authenticates the current user on the 1265 * server. This does not need any extra privileges. The basic connection 1266 * to the server must already have been established before this is called. 1267 * If login fails, this function prints an error and never returns. 1268 * This function does not require super-user privileges. 1269 */ 1270void 1271ssh_login(Sensitive *sensitive, const char *orighost, 1272 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1273{ 1274 char *host; 1275 char *server_user, *local_user; 1276 1277 local_user = xstrdup(pw->pw_name); 1278 server_user = options.user ? options.user : local_user; 1279 1280 /* Convert the user-supplied hostname into all lowercase. */ 1281 host = xstrdup(orighost); 1282 lowercase(host); 1283 1284 /* Exchange protocol version identification strings with the server. */ 1285 ssh_exchange_identification(timeout_ms); 1286 1287 /* Put the connection into non-blocking mode. */ 1288 packet_set_nonblocking(); 1289 1290 /* key exchange */ 1291 /* authenticate user */ 1292 if (compat20) { 1293 ssh_kex2(host, hostaddr, port); 1294 ssh_userauth2(local_user, server_user, host, sensitive); 1295 } else { 1296 ssh_kex(host, hostaddr); 1297 ssh_userauth1(local_user, server_user, host, sensitive); 1298 } 1299 free(local_user); 1300} 1301 1302void 1303ssh_put_password(char *password) 1304{ 1305 int size; 1306 char *padded; 1307 1308 if (datafellows & SSH_BUG_PASSWORDPAD) { 1309 packet_put_cstring(password); 1310 return; 1311 } 1312 size = roundup(strlen(password) + 1, 32); 1313 padded = xcalloc(1, size); 1314 strlcpy(padded, password, size); 1315 packet_put_string(padded, size); 1316 explicit_bzero(padded, size); 1317 free(padded); 1318} 1319 1320/* print all known host keys for a given host, but skip keys of given type */ 1321static int 1322show_other_keys(struct hostkeys *hostkeys, Key *key) 1323{ 1324 int type[] = { 1325 KEY_RSA1, 1326 KEY_RSA, 1327 KEY_DSA, 1328 KEY_ECDSA, 1329 KEY_ED25519, 1330 -1 1331 }; 1332 int i, ret = 0; 1333 char *fp, *ra; 1334 const struct hostkey_entry *found; 1335 1336 for (i = 0; type[i] != -1; i++) { 1337 if (type[i] == key->type) 1338 continue; 1339 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1340 continue; 1341 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX); 1342 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART); 1343 logit("WARNING: %s key found for host %s\n" 1344 "in %s:%lu\n" 1345 "%s key fingerprint %s.", 1346 key_type(found->key), 1347 found->host, found->file, found->line, 1348 key_type(found->key), fp); 1349 if (options.visual_host_key) 1350 logit("%s", ra); 1351 free(ra); 1352 free(fp); 1353 ret = 1; 1354 } 1355 return ret; 1356} 1357 1358static void 1359warn_changed_key(Key *host_key) 1360{ 1361 char *fp; 1362 1363 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 1364 1365 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1366 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1367 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1368 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1369 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1370 error("It is also possible that a host key has just been changed."); 1371 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1372 key_type(host_key), fp); 1373 error("Please contact your system administrator."); 1374 1375 free(fp); 1376} 1377 1378/* 1379 * Execute a local command 1380 */ 1381int 1382ssh_local_cmd(const char *args) 1383{ 1384 char *shell; 1385 pid_t pid; 1386 int status; 1387 void (*osighand)(int); 1388 1389 if (!options.permit_local_command || 1390 args == NULL || !*args) 1391 return (1); 1392 1393 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1394 shell = _PATH_BSHELL; 1395 1396 osighand = signal(SIGCHLD, SIG_DFL); 1397 pid = fork(); 1398 if (pid == 0) { 1399 signal(SIGPIPE, SIG_DFL); 1400 debug3("Executing %s -c \"%s\"", shell, args); 1401 execl(shell, shell, "-c", args, (char *)NULL); 1402 error("Couldn't execute %s -c \"%s\": %s", 1403 shell, args, strerror(errno)); 1404 _exit(1); 1405 } else if (pid == -1) 1406 fatal("fork failed: %.100s", strerror(errno)); 1407 while (waitpid(pid, &status, 0) == -1) 1408 if (errno != EINTR) 1409 fatal("Couldn't wait for child: %s", strerror(errno)); 1410 signal(SIGCHLD, osighand); 1411 1412 if (!WIFEXITED(status)) 1413 return (1); 1414 1415 return (WEXITSTATUS(status)); 1416} 1417