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 "includes.h" 17 __RCSID("$FreeBSD$"); 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 "misc.h" 60 #include "readconf.h" 61 #include "atomicio.h" 62 #include "dns.h" 63 #include "roaming.h" 64 #include "monitor_fdpass.h" 65 #include "ssh2.h" 66 #include "version.h" 67 68 char *client_version_string = NULL; 69 char *server_version_string = NULL; 70 Key *previous_host_key = NULL; 71 72 static int matching_host_key_dns = 0; 73 74 static pid_t proxy_command_pid = 0; 75 76 /* import */ 77 extern Options options; 78 extern char *__progname; 79 extern uid_t original_real_uid; 80 extern uid_t original_effective_uid; 81 82 static int show_other_keys(struct hostkeys *, Key *); 83 static void warn_changed_key(Key *); 84 85 /* Expand a proxy command */ 86 static char * 87 expand_proxy_command(const char *proxy_command, const char *user, 88 const char *host, int port) 89 { 90 char *tmp, *ret, strport[NI_MAXSERV]; 91 92 snprintf(strport, sizeof strport, "%d", port); 93 xasprintf(&tmp, "exec %s", proxy_command); 94 ret = percent_expand(tmp, "h", host, "p", strport, 95 "r", options.user, (char *)NULL); 96 free(tmp); 97 return ret; 98 } 99 100 /* 101 * Connect to the given ssh server using a proxy command that passes a 102 * a connected fd back to us. 103 */ 104 static int 105 ssh_proxy_fdpass_connect(const char *host, u_short port, 106 const char *proxy_command) 107 { 108 char *command_string; 109 int sp[2], sock; 110 pid_t pid; 111 char *shell; 112 113 if ((shell = getenv("SHELL")) == NULL) 114 shell = _PATH_BSHELL; 115 116 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 117 fatal("Could not create socketpair to communicate with " 118 "proxy dialer: %.100s", strerror(errno)); 119 120 command_string = expand_proxy_command(proxy_command, options.user, 121 host, port); 122 debug("Executing proxy dialer command: %.500s", command_string); 123 124 /* Fork and execute the proxy command. */ 125 if ((pid = fork()) == 0) { 126 char *argv[10]; 127 128 /* Child. Permanently give up superuser privileges. */ 129 permanently_drop_suid(original_real_uid); 130 131 close(sp[1]); 132 /* Redirect stdin and stdout. */ 133 if (sp[0] != 0) { 134 if (dup2(sp[0], 0) < 0) 135 perror("dup2 stdin"); 136 } 137 if (sp[0] != 1) { 138 if (dup2(sp[0], 1) < 0) 139 perror("dup2 stdout"); 140 } 141 if (sp[0] >= 2) 142 close(sp[0]); 143 144 /* 145 * Stderr is left as it is so that error messages get 146 * printed on the user's terminal. 147 */ 148 argv[0] = shell; 149 argv[1] = "-c"; 150 argv[2] = command_string; 151 argv[3] = NULL; 152 153 /* 154 * Execute the proxy command. 155 * Note that we gave up any extra privileges above. 156 */ 157 execv(argv[0], argv); 158 perror(argv[0]); 159 exit(1); 160 } 161 /* Parent. */ 162 if (pid < 0) 163 fatal("fork failed: %.100s", strerror(errno)); 164 close(sp[0]); 165 free(command_string); 166 167 if ((sock = mm_receive_fd(sp[1])) == -1) 168 fatal("proxy dialer did not pass back a connection"); 169 170 while (waitpid(pid, NULL, 0) == -1) 171 if (errno != EINTR) 172 fatal("Couldn't wait for child: %s", strerror(errno)); 173 174 /* Set the connection file descriptors. */ 175 packet_set_connection(sock, sock); 176 177 return 0; 178 } 179 180 /* 181 * Connect to the given ssh server using a proxy command. 182 */ 183 static int 184 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 185 { 186 char *command_string; 187 int pin[2], pout[2]; 188 pid_t pid; 189 char *shell; 190 191 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 192 shell = _PATH_BSHELL; 193 194 /* Create pipes for communicating with the proxy. */ 195 if (pipe(pin) < 0 || pipe(pout) < 0) 196 fatal("Could not create pipes to communicate with the proxy: %.100s", 197 strerror(errno)); 198 199 command_string = expand_proxy_command(proxy_command, options.user, 200 host, port); 201 debug("Executing proxy command: %.500s", command_string); 202 203 /* Fork and execute the proxy command. */ 204 if ((pid = fork()) == 0) { 205 char *argv[10]; 206 207 /* Child. Permanently give up superuser privileges. */ 208 permanently_drop_suid(original_real_uid); 209 210 /* Redirect stdin and stdout. */ 211 close(pin[1]); 212 if (pin[0] != 0) { 213 if (dup2(pin[0], 0) < 0) 214 perror("dup2 stdin"); 215 close(pin[0]); 216 } 217 close(pout[0]); 218 if (dup2(pout[1], 1) < 0) 219 perror("dup2 stdout"); 220 /* Cannot be 1 because pin allocated two descriptors. */ 221 close(pout[1]); 222 223 /* Stderr is left as it is so that error messages get 224 printed on the user's terminal. */ 225 argv[0] = shell; 226 argv[1] = "-c"; 227 argv[2] = command_string; 228 argv[3] = NULL; 229 230 /* Execute the proxy command. Note that we gave up any 231 extra privileges above. */ 232 signal(SIGPIPE, SIG_DFL); 233 execv(argv[0], argv); 234 perror(argv[0]); 235 exit(1); 236 } 237 /* Parent. */ 238 if (pid < 0) 239 fatal("fork failed: %.100s", strerror(errno)); 240 else 241 proxy_command_pid = pid; /* save pid to clean up later */ 242 243 /* Close child side of the descriptors. */ 244 close(pin[0]); 245 close(pout[1]); 246 247 /* Free the command name. */ 248 free(command_string); 249 250 /* Set the connection file descriptors. */ 251 packet_set_connection(pout[0], pin[1]); 252 253 /* Indicate OK return */ 254 return 0; 255 } 256 257 void 258 ssh_kill_proxy_command(void) 259 { 260 /* 261 * Send SIGHUP to proxy command if used. We don't wait() in 262 * case it hangs and instead rely on init to reap the child 263 */ 264 if (proxy_command_pid > 1) 265 kill(proxy_command_pid, SIGHUP); 266 } 267 268 /* 269 * Creates a (possibly privileged) socket for use as the ssh connection. 270 */ 271 static int 272 ssh_create_socket(int privileged, struct addrinfo *ai) 273 { 274 int sock, r, gaierr; 275 struct addrinfo hints, *res = NULL; 276 277 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 278 if (sock < 0) { 279 error("socket: %s", strerror(errno)); 280 return -1; 281 } 282 fcntl(sock, F_SETFD, FD_CLOEXEC); 283 284 /* Bind the socket to an alternative local IP address */ 285 if (options.bind_address == NULL && !privileged) 286 return sock; 287 288 if (options.bind_address) { 289 memset(&hints, 0, sizeof(hints)); 290 hints.ai_family = ai->ai_family; 291 hints.ai_socktype = ai->ai_socktype; 292 hints.ai_protocol = ai->ai_protocol; 293 hints.ai_flags = AI_PASSIVE; 294 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 295 if (gaierr) { 296 error("getaddrinfo: %s: %s", options.bind_address, 297 ssh_gai_strerror(gaierr)); 298 close(sock); 299 return -1; 300 } 301 } 302 /* 303 * If we are running as root and want to connect to a privileged 304 * port, bind our own socket to a privileged port. 305 */ 306 if (privileged) { 307 PRIV_START; 308 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 309 PRIV_END; 310 if (r < 0) { 311 error("bindresvport_sa: af=%d %s", ai->ai_family, 312 strerror(errno)); 313 goto fail; 314 } 315 } else { 316 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 317 error("bind: %s: %s", options.bind_address, 318 strerror(errno)); 319 fail: 320 close(sock); 321 freeaddrinfo(res); 322 return -1; 323 } 324 } 325 if (res != NULL) 326 freeaddrinfo(res); 327 return sock; 328 } 329 330 static int 331 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 332 socklen_t addrlen, int *timeoutp) 333 { 334 fd_set *fdset; 335 struct timeval tv, t_start; 336 socklen_t optlen; 337 int optval, rc, result = -1; 338 339 gettimeofday(&t_start, NULL); 340 341 if (*timeoutp <= 0) { 342 result = connect(sockfd, serv_addr, addrlen); 343 goto done; 344 } 345 346 set_nonblock(sockfd); 347 rc = connect(sockfd, serv_addr, addrlen); 348 if (rc == 0) { 349 unset_nonblock(sockfd); 350 result = 0; 351 goto done; 352 } 353 if (errno != EINPROGRESS) { 354 result = -1; 355 goto done; 356 } 357 358 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), 359 sizeof(fd_mask)); 360 FD_SET(sockfd, fdset); 361 ms_to_timeval(&tv, *timeoutp); 362 363 for (;;) { 364 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 365 if (rc != -1 || errno != EINTR) 366 break; 367 } 368 369 switch (rc) { 370 case 0: 371 /* Timed out */ 372 errno = ETIMEDOUT; 373 break; 374 case -1: 375 /* Select error */ 376 debug("select: %s", strerror(errno)); 377 break; 378 case 1: 379 /* Completed or failed */ 380 optval = 0; 381 optlen = sizeof(optval); 382 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 383 &optlen) == -1) { 384 debug("getsockopt: %s", strerror(errno)); 385 break; 386 } 387 if (optval != 0) { 388 errno = optval; 389 break; 390 } 391 result = 0; 392 unset_nonblock(sockfd); 393 break; 394 default: 395 /* Should not occur */ 396 fatal("Bogus return (%d) from select()", rc); 397 } 398 399 free(fdset); 400 401 done: 402 if (result == 0 && *timeoutp > 0) { 403 ms_subtract_diff(&t_start, timeoutp); 404 if (*timeoutp <= 0) { 405 errno = ETIMEDOUT; 406 result = -1; 407 } 408 } 409 410 return (result); 411 } 412 413 /* 414 * Opens a TCP/IP connection to the remote server on the given host. 415 * The address of the remote host will be returned in hostaddr. 416 * If port is 0, the default port will be used. If needpriv is true, 417 * a privileged port will be allocated to make the connection. 418 * This requires super-user privileges if needpriv is true. 419 * Connection_attempts specifies the maximum number of tries (one per 420 * second). If proxy_command is non-NULL, it specifies the command (with %h 421 * and %p substituted for host and port, respectively) to use to contact 422 * the daemon. 423 */ 424 static int 425 ssh_connect_direct(const char *host, struct addrinfo *aitop, 426 struct sockaddr_storage *hostaddr, u_short port, int family, 427 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 428 { 429 int on = 1; 430 int sock = -1, attempt; 431 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 432 struct addrinfo *ai; 433 434 debug2("ssh_connect: needpriv %d", needpriv); 435 436 for (attempt = 0; attempt < connection_attempts; attempt++) { 437 if (attempt > 0) { 438 /* Sleep a moment before retrying. */ 439 sleep(1); 440 debug("Trying again..."); 441 } 442 /* 443 * Loop through addresses for this host, and try each one in 444 * sequence until the connection succeeds. 445 */ 446 for (ai = aitop; ai; ai = ai->ai_next) { 447 if (ai->ai_family != AF_INET && 448 ai->ai_family != AF_INET6) 449 continue; 450 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 451 ntop, sizeof(ntop), strport, sizeof(strport), 452 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 453 error("ssh_connect: getnameinfo failed"); 454 continue; 455 } 456 debug("Connecting to %.200s [%.100s] port %s.", 457 host, ntop, strport); 458 459 /* Create a socket for connecting. */ 460 sock = ssh_create_socket(needpriv, ai); 461 if (sock < 0) 462 /* Any error is already output */ 463 continue; 464 465 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 466 timeout_ms) >= 0) { 467 /* Successful connection. */ 468 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 469 break; 470 } else { 471 debug("connect to address %s port %s: %s", 472 ntop, strport, strerror(errno)); 473 close(sock); 474 sock = -1; 475 } 476 } 477 if (sock != -1) 478 break; /* Successful connection. */ 479 } 480 481 /* Return failure if we didn't get a successful connection. */ 482 if (sock == -1) { 483 error("ssh: connect to host %s port %s: %s", 484 host, strport, strerror(errno)); 485 return (-1); 486 } 487 488 debug("Connection established."); 489 490 /* Set SO_KEEPALIVE if requested. */ 491 if (want_keepalive && 492 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 493 sizeof(on)) < 0) 494 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 495 496 /* Set the connection. */ 497 packet_set_connection(sock, sock); 498 499 return 0; 500 } 501 502 int 503 ssh_connect(const char *host, struct addrinfo *addrs, 504 struct sockaddr_storage *hostaddr, u_short port, int family, 505 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 506 { 507 if (options.proxy_command == NULL) { 508 return ssh_connect_direct(host, addrs, hostaddr, port, family, 509 connection_attempts, timeout_ms, want_keepalive, needpriv); 510 } else if (strcmp(options.proxy_command, "-") == 0) { 511 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 512 return 0; /* Always succeeds */ 513 } else if (options.proxy_use_fdpass) { 514 return ssh_proxy_fdpass_connect(host, port, 515 options.proxy_command); 516 } 517 return ssh_proxy_connect(host, port, options.proxy_command); 518 } 519 520 static void 521 send_client_banner(int connection_out, int minor1) 522 { 523 /* Send our own protocol version identification. */ 524 xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s%s", 525 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 526 compat20 ? PROTOCOL_MINOR_2 : minor1, 527 SSH_VERSION, 528 *options.version_addendum == '\0' ? "" : " ", 529 options.version_addendum, compat20 ? "\r\n" : "\n"); 530 if (roaming_atomicio(vwrite, connection_out, client_version_string, 531 strlen(client_version_string)) != strlen(client_version_string)) 532 fatal("write: %.100s", strerror(errno)); 533 chop(client_version_string); 534 debug("Local version string %.100s", client_version_string); 535 } 536 537 /* 538 * Waits for the server identification string, and sends our own 539 * identification string. 540 */ 541 void 542 ssh_exchange_identification(int timeout_ms) 543 { 544 char buf[256], remote_version[256]; /* must be same size! */ 545 int remote_major, remote_minor, mismatch; 546 int connection_in = packet_get_connection_in(); 547 int connection_out = packet_get_connection_out(); 548 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 549 u_int i, n; 550 size_t len; 551 int fdsetsz, remaining, rc; 552 struct timeval t_start, t_remaining; 553 fd_set *fdset; 554 555 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 556 fdset = xcalloc(1, fdsetsz); 557 558 /* 559 * If we are SSH2-only then we can send the banner immediately and 560 * save a round-trip. 561 */ 562 if (options.protocol == SSH_PROTO_2) { 563 enable_compat20(); 564 send_client_banner(connection_out, 0); 565 client_banner_sent = 1; 566 } 567 568 /* Read other side's version identification. */ 569 remaining = timeout_ms; 570 for (n = 0;;) { 571 for (i = 0; i < sizeof(buf) - 1; i++) { 572 if (timeout_ms > 0) { 573 gettimeofday(&t_start, NULL); 574 ms_to_timeval(&t_remaining, remaining); 575 FD_SET(connection_in, fdset); 576 rc = select(connection_in + 1, fdset, NULL, 577 fdset, &t_remaining); 578 ms_subtract_diff(&t_start, &remaining); 579 if (rc == 0 || remaining <= 0) 580 fatal("Connection timed out during " 581 "banner exchange"); 582 if (rc == -1) { 583 if (errno == EINTR) 584 continue; 585 fatal("ssh_exchange_identification: " 586 "select: %s", strerror(errno)); 587 } 588 } 589 590 len = roaming_atomicio(read, connection_in, &buf[i], 1); 591 592 if (len != 1 && errno == EPIPE) 593 fatal("ssh_exchange_identification: " 594 "Connection closed by remote host"); 595 else if (len != 1) 596 fatal("ssh_exchange_identification: " 597 "read: %.100s", strerror(errno)); 598 if (buf[i] == '\r') { 599 buf[i] = '\n'; 600 buf[i + 1] = 0; 601 continue; /**XXX wait for \n */ 602 } 603 if (buf[i] == '\n') { 604 buf[i + 1] = 0; 605 break; 606 } 607 if (++n > 65536) 608 fatal("ssh_exchange_identification: " 609 "No banner received"); 610 } 611 buf[sizeof(buf) - 1] = 0; 612 if (strncmp(buf, "SSH-", 4) == 0) 613 break; 614 debug("ssh_exchange_identification: %s", buf); 615 } 616 server_version_string = xstrdup(buf); 617 free(fdset); 618 619 /* 620 * Check that the versions match. In future this might accept 621 * several versions and set appropriate flags to handle them. 622 */ 623 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 624 &remote_major, &remote_minor, remote_version) != 3) 625 fatal("Bad remote protocol version identification: '%.100s'", buf); 626 debug("Remote protocol version %d.%d, remote software version %.100s", 627 remote_major, remote_minor, remote_version); 628 629 compat_datafellows(remote_version); 630 mismatch = 0; 631 632 switch (remote_major) { 633 case 1: 634 if (remote_minor == 99 && 635 (options.protocol & SSH_PROTO_2) && 636 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 637 enable_compat20(); 638 break; 639 } 640 if (!(options.protocol & SSH_PROTO_1)) { 641 mismatch = 1; 642 break; 643 } 644 if (remote_minor < 3) { 645 fatal("Remote machine has too old SSH software version."); 646 } else if (remote_minor == 3 || remote_minor == 4) { 647 /* We speak 1.3, too. */ 648 enable_compat13(); 649 minor1 = 3; 650 if (options.forward_agent) { 651 logit("Agent forwarding disabled for protocol 1.3"); 652 options.forward_agent = 0; 653 } 654 } 655 break; 656 case 2: 657 if (options.protocol & SSH_PROTO_2) { 658 enable_compat20(); 659 break; 660 } 661 /* FALLTHROUGH */ 662 default: 663 mismatch = 1; 664 break; 665 } 666 if (mismatch) 667 fatal("Protocol major versions differ: %d vs. %d", 668 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 669 remote_major); 670 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 671 fatal("Server version \"%.100s\" uses unsafe key agreement; " 672 "refusing connection", remote_version); 673 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 674 logit("Server version \"%.100s\" uses unsafe RSA signature " 675 "scheme; disabling use of RSA keys", remote_version); 676 if (!client_banner_sent) 677 send_client_banner(connection_out, minor1); 678 chop(server_version_string); 679 } 680 681 /* defaults to 'no' */ 682 static int 683 confirm(const char *prompt) 684 { 685 const char *msg, *again = "Please type 'yes' or 'no': "; 686 char *p; 687 int ret = -1; 688 689 if (options.batch_mode) 690 return 0; 691 for (msg = prompt;;msg = again) { 692 p = read_passphrase(msg, RP_ECHO); 693 if (p == NULL || 694 (p[0] == '\0') || (p[0] == '\n') || 695 strncasecmp(p, "no", 2) == 0) 696 ret = 0; 697 if (p && strncasecmp(p, "yes", 3) == 0) 698 ret = 1; 699 free(p); 700 if (ret != -1) 701 return ret; 702 } 703 } 704 705 static int 706 check_host_cert(const char *host, const Key *host_key) 707 { 708 const char *reason; 709 710 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 711 error("%s", reason); 712 return 0; 713 } 714 if (buffer_len(host_key->cert->critical) != 0) { 715 error("Certificate for %s contains unsupported " 716 "critical options(s)", host); 717 return 0; 718 } 719 return 1; 720 } 721 722 static int 723 sockaddr_is_local(struct sockaddr *hostaddr) 724 { 725 switch (hostaddr->sa_family) { 726 case AF_INET: 727 return (ntohl(((struct sockaddr_in *)hostaddr)-> 728 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 729 case AF_INET6: 730 return IN6_IS_ADDR_LOOPBACK( 731 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 732 default: 733 return 0; 734 } 735 } 736 737 /* 738 * Prepare the hostname and ip address strings that are used to lookup 739 * host keys in known_hosts files. These may have a port number appended. 740 */ 741 void 742 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 743 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 744 { 745 char ntop[NI_MAXHOST]; 746 socklen_t addrlen; 747 748 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 749 case -1: 750 addrlen = 0; 751 break; 752 case AF_INET: 753 addrlen = sizeof(struct sockaddr_in); 754 break; 755 case AF_INET6: 756 addrlen = sizeof(struct sockaddr_in6); 757 break; 758 default: 759 addrlen = sizeof(struct sockaddr); 760 break; 761 } 762 763 /* 764 * We don't have the remote ip-address for connections 765 * using a proxy command 766 */ 767 if (hostfile_ipaddr != NULL) { 768 if (options.proxy_command == NULL) { 769 if (getnameinfo(hostaddr, addrlen, 770 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 771 fatal("check_host_key: getnameinfo failed"); 772 *hostfile_ipaddr = put_host_port(ntop, port); 773 } else { 774 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 775 "command>"); 776 } 777 } 778 779 /* 780 * Allow the user to record the key under a different name or 781 * differentiate a non-standard port. This is useful for ssh 782 * tunneling over forwarded connections or if you run multiple 783 * sshd's on different ports on the same machine. 784 */ 785 if (hostfile_hostname != NULL) { 786 if (options.host_key_alias != NULL) { 787 *hostfile_hostname = xstrdup(options.host_key_alias); 788 debug("using hostkeyalias: %s", *hostfile_hostname); 789 } else { 790 *hostfile_hostname = put_host_port(hostname, port); 791 } 792 } 793 } 794 795 /* 796 * check whether the supplied host key is valid, return -1 if the key 797 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 798 */ 799 #define RDRW 0 800 #define RDONLY 1 801 #define ROQUIET 2 802 static int 803 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 804 Key *host_key, int readonly, 805 char **user_hostfiles, u_int num_user_hostfiles, 806 char **system_hostfiles, u_int num_system_hostfiles) 807 { 808 HostStatus host_status; 809 HostStatus ip_status; 810 Key *raw_key = NULL; 811 char *ip = NULL, *host = NULL; 812 char hostline[1000], *hostp, *fp, *ra; 813 char msg[1024]; 814 const char *type; 815 const struct hostkey_entry *host_found, *ip_found; 816 int len, cancelled_forwarding = 0; 817 int local = sockaddr_is_local(hostaddr); 818 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 819 struct hostkeys *host_hostkeys, *ip_hostkeys; 820 u_int i; 821 822 /* 823 * Force accepting of the host key for loopback/localhost. The 824 * problem is that if the home directory is NFS-mounted to multiple 825 * machines, localhost will refer to a different machine in each of 826 * them, and the user will get bogus HOST_CHANGED warnings. This 827 * essentially disables host authentication for localhost; however, 828 * this is probably not a real problem. 829 */ 830 if (options.no_host_authentication_for_localhost == 1 && local && 831 options.host_key_alias == NULL) { 832 debug("Forcing accepting of host key for " 833 "loopback/localhost."); 834 return 0; 835 } 836 837 /* 838 * Prepare the hostname and address strings used for hostkey lookup. 839 * In some cases, these will have a port number appended. 840 */ 841 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 842 843 /* 844 * Turn off check_host_ip if the connection is to localhost, via proxy 845 * command or if we don't have a hostname to compare with 846 */ 847 if (options.check_host_ip && (local || 848 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 849 options.check_host_ip = 0; 850 851 host_hostkeys = init_hostkeys(); 852 for (i = 0; i < num_user_hostfiles; i++) 853 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 854 for (i = 0; i < num_system_hostfiles; i++) 855 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 856 857 ip_hostkeys = NULL; 858 if (!want_cert && options.check_host_ip) { 859 ip_hostkeys = init_hostkeys(); 860 for (i = 0; i < num_user_hostfiles; i++) 861 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 862 for (i = 0; i < num_system_hostfiles; i++) 863 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 864 } 865 866 retry: 867 /* Reload these as they may have changed on cert->key downgrade */ 868 want_cert = key_is_cert(host_key); 869 type = key_type(host_key); 870 871 /* 872 * Check if the host key is present in the user's list of known 873 * hosts or in the systemwide list. 874 */ 875 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 876 &host_found); 877 878 /* 879 * Also perform check for the ip address, skip the check if we are 880 * localhost, looking for a certificate, or the hostname was an ip 881 * address to begin with. 882 */ 883 if (!want_cert && ip_hostkeys != NULL) { 884 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 885 &ip_found); 886 if (host_status == HOST_CHANGED && 887 (ip_status != HOST_CHANGED || 888 (ip_found != NULL && 889 !key_equal(ip_found->key, host_found->key)))) 890 host_ip_differ = 1; 891 } else 892 ip_status = host_status; 893 894 switch (host_status) { 895 case HOST_OK: 896 /* The host is known and the key matches. */ 897 debug("Host '%.200s' is known and matches the %s host %s.", 898 host, type, want_cert ? "certificate" : "key"); 899 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 900 host_found->file, host_found->line); 901 if (want_cert && !check_host_cert(hostname, host_key)) 902 goto fail; 903 if (options.check_host_ip && ip_status == HOST_NEW) { 904 if (readonly || want_cert) 905 logit("%s host key for IP address " 906 "'%.128s' not in list of known hosts.", 907 type, ip); 908 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 909 host_key, options.hash_known_hosts)) 910 logit("Failed to add the %s host key for IP " 911 "address '%.128s' to the list of known " 912 "hosts (%.30s).", type, ip, 913 user_hostfiles[0]); 914 else 915 logit("Warning: Permanently added the %s host " 916 "key for IP address '%.128s' to the list " 917 "of known hosts.", type, ip); 918 } else if (options.visual_host_key) { 919 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 920 ra = key_fingerprint(host_key, SSH_FP_MD5, 921 SSH_FP_RANDOMART); 922 logit("Host key fingerprint is %s\n%s\n", fp, ra); 923 free(ra); 924 free(fp); 925 } 926 break; 927 case HOST_NEW: 928 if (options.host_key_alias == NULL && port != 0 && 929 port != SSH_DEFAULT_PORT) { 930 debug("checking without port identifier"); 931 if (check_host_key(hostname, hostaddr, 0, host_key, 932 ROQUIET, user_hostfiles, num_user_hostfiles, 933 system_hostfiles, num_system_hostfiles) == 0) { 934 debug("found matching key w/out port"); 935 break; 936 } 937 } 938 if (readonly || want_cert) 939 goto fail; 940 /* The host is new. */ 941 if (options.strict_host_key_checking == 1) { 942 /* 943 * User has requested strict host key checking. We 944 * will not add the host key automatically. The only 945 * alternative left is to abort. 946 */ 947 error("No %s host key is known for %.200s and you " 948 "have requested strict checking.", type, host); 949 goto fail; 950 } else if (options.strict_host_key_checking == 2) { 951 char msg1[1024], msg2[1024]; 952 953 if (show_other_keys(host_hostkeys, host_key)) 954 snprintf(msg1, sizeof(msg1), 955 "\nbut keys of different type are already" 956 " known for this host."); 957 else 958 snprintf(msg1, sizeof(msg1), "."); 959 /* The default */ 960 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 961 ra = key_fingerprint(host_key, SSH_FP_MD5, 962 SSH_FP_RANDOMART); 963 msg2[0] = '\0'; 964 if (options.verify_host_key_dns) { 965 if (matching_host_key_dns) 966 snprintf(msg2, sizeof(msg2), 967 "Matching host key fingerprint" 968 " found in DNS.\n"); 969 else 970 snprintf(msg2, sizeof(msg2), 971 "No matching host key fingerprint" 972 " found in DNS.\n"); 973 } 974 snprintf(msg, sizeof(msg), 975 "The authenticity of host '%.200s (%s)' can't be " 976 "established%s\n" 977 "%s key fingerprint is %s.%s%s\n%s" 978 "Are you sure you want to continue connecting " 979 "(yes/no)? ", 980 host, ip, msg1, type, fp, 981 options.visual_host_key ? "\n" : "", 982 options.visual_host_key ? ra : "", 983 msg2); 984 free(ra); 985 free(fp); 986 if (!confirm(msg)) 987 goto fail; 988 } 989 /* 990 * If not in strict mode, add the key automatically to the 991 * local known_hosts file. 992 */ 993 if (options.check_host_ip && ip_status == HOST_NEW) { 994 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 995 hostp = hostline; 996 if (options.hash_known_hosts) { 997 /* Add hash of host and IP separately */ 998 r = add_host_to_hostfile(user_hostfiles[0], 999 host, host_key, options.hash_known_hosts) && 1000 add_host_to_hostfile(user_hostfiles[0], ip, 1001 host_key, options.hash_known_hosts); 1002 } else { 1003 /* Add unhashed "host,ip" */ 1004 r = add_host_to_hostfile(user_hostfiles[0], 1005 hostline, host_key, 1006 options.hash_known_hosts); 1007 } 1008 } else { 1009 r = add_host_to_hostfile(user_hostfiles[0], host, 1010 host_key, options.hash_known_hosts); 1011 hostp = host; 1012 } 1013 1014 if (!r) 1015 logit("Failed to add the host to the list of known " 1016 "hosts (%.500s).", user_hostfiles[0]); 1017 else 1018 logit("Warning: Permanently added '%.200s' (%s) to the " 1019 "list of known hosts.", hostp, type); 1020 break; 1021 case HOST_REVOKED: 1022 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1023 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1024 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1025 error("The %s host key for %s is marked as revoked.", type, host); 1026 error("This could mean that a stolen key is being used to"); 1027 error("impersonate this host."); 1028 1029 /* 1030 * If strict host key checking is in use, the user will have 1031 * to edit the key manually and we can only abort. 1032 */ 1033 if (options.strict_host_key_checking) { 1034 error("%s host key for %.200s was revoked and you have " 1035 "requested strict checking.", type, host); 1036 goto fail; 1037 } 1038 goto continue_unsafe; 1039 1040 case HOST_CHANGED: 1041 if (want_cert) { 1042 /* 1043 * This is only a debug() since it is valid to have 1044 * CAs with wildcard DNS matches that don't match 1045 * all hosts that one might visit. 1046 */ 1047 debug("Host certificate authority does not " 1048 "match %s in %s:%lu", CA_MARKER, 1049 host_found->file, host_found->line); 1050 goto fail; 1051 } 1052 if (readonly == ROQUIET) 1053 goto fail; 1054 if (options.check_host_ip && host_ip_differ) { 1055 char *key_msg; 1056 if (ip_status == HOST_NEW) 1057 key_msg = "is unknown"; 1058 else if (ip_status == HOST_OK) 1059 key_msg = "is unchanged"; 1060 else 1061 key_msg = "has a different value"; 1062 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1063 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1064 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1065 error("The %s host key for %s has changed,", type, host); 1066 error("and the key for the corresponding IP address %s", ip); 1067 error("%s. This could either mean that", key_msg); 1068 error("DNS SPOOFING is happening or the IP address for the host"); 1069 error("and its host key have changed at the same time."); 1070 if (ip_status != HOST_NEW) 1071 error("Offending key for IP in %s:%lu", 1072 ip_found->file, ip_found->line); 1073 } 1074 /* The host key has changed. */ 1075 warn_changed_key(host_key); 1076 error("Add correct host key in %.100s to get rid of this message.", 1077 user_hostfiles[0]); 1078 error("Offending %s key in %s:%lu", key_type(host_found->key), 1079 host_found->file, host_found->line); 1080 1081 /* 1082 * If strict host key checking is in use, the user will have 1083 * to edit the key manually and we can only abort. 1084 */ 1085 if (options.strict_host_key_checking) { 1086 error("%s host key for %.200s has changed and you have " 1087 "requested strict checking.", type, host); 1088 goto fail; 1089 } 1090 1091 continue_unsafe: 1092 /* 1093 * If strict host key checking has not been requested, allow 1094 * the connection but without MITM-able authentication or 1095 * forwarding. 1096 */ 1097 if (options.password_authentication) { 1098 error("Password authentication is disabled to avoid " 1099 "man-in-the-middle attacks."); 1100 options.password_authentication = 0; 1101 cancelled_forwarding = 1; 1102 } 1103 if (options.kbd_interactive_authentication) { 1104 error("Keyboard-interactive authentication is disabled" 1105 " to avoid man-in-the-middle attacks."); 1106 options.kbd_interactive_authentication = 0; 1107 options.challenge_response_authentication = 0; 1108 cancelled_forwarding = 1; 1109 } 1110 if (options.challenge_response_authentication) { 1111 error("Challenge/response authentication is disabled" 1112 " to avoid man-in-the-middle attacks."); 1113 options.challenge_response_authentication = 0; 1114 cancelled_forwarding = 1; 1115 } 1116 if (options.forward_agent) { 1117 error("Agent forwarding is disabled to avoid " 1118 "man-in-the-middle attacks."); 1119 options.forward_agent = 0; 1120 cancelled_forwarding = 1; 1121 } 1122 if (options.forward_x11) { 1123 error("X11 forwarding is disabled to avoid " 1124 "man-in-the-middle attacks."); 1125 options.forward_x11 = 0; 1126 cancelled_forwarding = 1; 1127 } 1128 if (options.num_local_forwards > 0 || 1129 options.num_remote_forwards > 0) { 1130 error("Port forwarding is disabled to avoid " 1131 "man-in-the-middle attacks."); 1132 options.num_local_forwards = 1133 options.num_remote_forwards = 0; 1134 cancelled_forwarding = 1; 1135 } 1136 if (options.tun_open != SSH_TUNMODE_NO) { 1137 error("Tunnel forwarding is disabled to avoid " 1138 "man-in-the-middle attacks."); 1139 options.tun_open = SSH_TUNMODE_NO; 1140 cancelled_forwarding = 1; 1141 } 1142 if (options.exit_on_forward_failure && cancelled_forwarding) 1143 fatal("Error: forwarding disabled due to host key " 1144 "check failure"); 1145 1146 /* 1147 * XXX Should permit the user to change to use the new id. 1148 * This could be done by converting the host key to an 1149 * identifying sentence, tell that the host identifies itself 1150 * by that sentence, and ask the user if he/she wishes to 1151 * accept the authentication. 1152 */ 1153 break; 1154 case HOST_FOUND: 1155 fatal("internal error"); 1156 break; 1157 } 1158 1159 if (options.check_host_ip && host_status != HOST_CHANGED && 1160 ip_status == HOST_CHANGED) { 1161 snprintf(msg, sizeof(msg), 1162 "Warning: the %s host key for '%.200s' " 1163 "differs from the key for the IP address '%.128s'" 1164 "\nOffending key for IP in %s:%lu", 1165 type, host, ip, ip_found->file, ip_found->line); 1166 if (host_status == HOST_OK) { 1167 len = strlen(msg); 1168 snprintf(msg + len, sizeof(msg) - len, 1169 "\nMatching host key in %s:%lu", 1170 host_found->file, host_found->line); 1171 } 1172 if (options.strict_host_key_checking == 1) { 1173 logit("%s", msg); 1174 error("Exiting, you have requested strict checking."); 1175 goto fail; 1176 } else if (options.strict_host_key_checking == 2) { 1177 strlcat(msg, "\nAre you sure you want " 1178 "to continue connecting (yes/no)? ", sizeof(msg)); 1179 if (!confirm(msg)) 1180 goto fail; 1181 } else { 1182 logit("%s", msg); 1183 } 1184 } 1185 1186 free(ip); 1187 free(host); 1188 if (host_hostkeys != NULL) 1189 free_hostkeys(host_hostkeys); 1190 if (ip_hostkeys != NULL) 1191 free_hostkeys(ip_hostkeys); 1192 return 0; 1193 1194 fail: 1195 if (want_cert && host_status != HOST_REVOKED) { 1196 /* 1197 * No matching certificate. Downgrade cert to raw key and 1198 * search normally. 1199 */ 1200 debug("No matching CA found. Retry with plain key"); 1201 raw_key = key_from_private(host_key); 1202 if (key_drop_cert(raw_key) != 0) 1203 fatal("Couldn't drop certificate"); 1204 host_key = raw_key; 1205 goto retry; 1206 } 1207 if (raw_key != NULL) 1208 key_free(raw_key); 1209 free(ip); 1210 free(host); 1211 if (host_hostkeys != NULL) 1212 free_hostkeys(host_hostkeys); 1213 if (ip_hostkeys != NULL) 1214 free_hostkeys(ip_hostkeys); 1215 return -1; 1216 } 1217 1218 /* returns 0 if key verifies or -1 if key does NOT verify */ 1219 int 1220 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1221 { 1222 int r = -1, flags = 0; 1223 char *fp; 1224 Key *plain = NULL; 1225 1226 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 1227 debug("Server host key: %s %s", key_type(host_key), fp); 1228 free(fp); 1229 1230 if (key_equal(previous_host_key, host_key)) { 1231 debug("%s: server host key matches cached key", __func__); 1232 return 0; 1233 } 1234 1235 if (options.verify_host_key_dns) { 1236 /* 1237 * XXX certs are not yet supported for DNS, so downgrade 1238 * them and try the plain key. 1239 */ 1240 plain = key_from_private(host_key); 1241 if (key_is_cert(plain)) 1242 key_drop_cert(plain); 1243 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1244 if (flags & DNS_VERIFY_FOUND) { 1245 if (options.verify_host_key_dns == 1 && 1246 flags & DNS_VERIFY_MATCH && 1247 flags & DNS_VERIFY_SECURE) { 1248 key_free(plain); 1249 r = 0; 1250 goto done; 1251 } 1252 if (flags & DNS_VERIFY_MATCH) { 1253 matching_host_key_dns = 1; 1254 } else { 1255 warn_changed_key(plain); 1256 error("Update the SSHFP RR in DNS " 1257 "with the new host key to get rid " 1258 "of this message."); 1259 } 1260 } 1261 } 1262 key_free(plain); 1263 } 1264 1265 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1266 options.user_hostfiles, options.num_user_hostfiles, 1267 options.system_hostfiles, options.num_system_hostfiles); 1268 1269 done: 1270 if (r == 0 && host_key != NULL) { 1271 key_free(previous_host_key); 1272 previous_host_key = key_from_private(host_key); 1273 } 1274 1275 return r; 1276 } 1277 1278 /* 1279 * Starts a dialog with the server, and authenticates the current user on the 1280 * server. This does not need any extra privileges. The basic connection 1281 * to the server must already have been established before this is called. 1282 * If login fails, this function prints an error and never returns. 1283 * This function does not require super-user privileges. 1284 */ 1285 void 1286 ssh_login(Sensitive *sensitive, const char *orighost, 1287 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1288 { 1289 char *host; 1290 char *server_user, *local_user; 1291 1292 local_user = xstrdup(pw->pw_name); 1293 server_user = options.user ? options.user : local_user; 1294 1295 /* Convert the user-supplied hostname into all lowercase. */ 1296 host = xstrdup(orighost); 1297 lowercase(host); 1298 1299 /* Exchange protocol version identification strings with the server. */ 1300 ssh_exchange_identification(timeout_ms); 1301 1302 /* Put the connection into non-blocking mode. */ 1303 packet_set_nonblocking(); 1304 1305 /* key exchange */ 1306 /* authenticate user */ 1307 if (compat20) { 1308 ssh_kex2(host, hostaddr, port); 1309 ssh_userauth2(local_user, server_user, host, sensitive); 1310 } else { 1311 #ifdef WITH_SSH1 1312 ssh_kex(host, hostaddr); 1313 ssh_userauth1(local_user, server_user, host, sensitive); 1314 #else 1315 fatal("ssh1 is not unsupported"); 1316 #endif 1317 } 1318 free(local_user); 1319 } 1320 1321 void 1322 ssh_put_password(char *password) 1323 { 1324 int size; 1325 char *padded; 1326 1327 if (datafellows & SSH_BUG_PASSWORDPAD) { 1328 packet_put_cstring(password); 1329 return; 1330 } 1331 size = roundup(strlen(password) + 1, 32); 1332 padded = xcalloc(1, size); 1333 strlcpy(padded, password, size); 1334 packet_put_string(padded, size); 1335 explicit_bzero(padded, size); 1336 free(padded); 1337 } 1338 1339 /* print all known host keys for a given host, but skip keys of given type */ 1340 static int 1341 show_other_keys(struct hostkeys *hostkeys, Key *key) 1342 { 1343 int type[] = { 1344 KEY_RSA1, 1345 KEY_RSA, 1346 KEY_DSA, 1347 KEY_ECDSA, 1348 KEY_ED25519, 1349 -1 1350 }; 1351 int i, ret = 0; 1352 char *fp, *ra; 1353 const struct hostkey_entry *found; 1354 1355 for (i = 0; type[i] != -1; i++) { 1356 if (type[i] == key->type) 1357 continue; 1358 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1359 continue; 1360 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX); 1361 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART); 1362 logit("WARNING: %s key found for host %s\n" 1363 "in %s:%lu\n" 1364 "%s key fingerprint %s.", 1365 key_type(found->key), 1366 found->host, found->file, found->line, 1367 key_type(found->key), fp); 1368 if (options.visual_host_key) 1369 logit("%s", ra); 1370 free(ra); 1371 free(fp); 1372 ret = 1; 1373 } 1374 return ret; 1375 } 1376 1377 static void 1378 warn_changed_key(Key *host_key) 1379 { 1380 char *fp; 1381 1382 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); 1383 1384 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1385 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1386 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1387 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1388 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1389 error("It is also possible that a host key has just been changed."); 1390 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1391 key_type(host_key), fp); 1392 error("Please contact your system administrator."); 1393 1394 free(fp); 1395 } 1396 1397 /* 1398 * Execute a local command 1399 */ 1400 int 1401 ssh_local_cmd(const char *args) 1402 { 1403 char *shell; 1404 pid_t pid; 1405 int status; 1406 void (*osighand)(int); 1407 1408 if (!options.permit_local_command || 1409 args == NULL || !*args) 1410 return (1); 1411 1412 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1413 shell = _PATH_BSHELL; 1414 1415 osighand = signal(SIGCHLD, SIG_DFL); 1416 pid = fork(); 1417 if (pid == 0) { 1418 signal(SIGPIPE, SIG_DFL); 1419 debug3("Executing %s -c \"%s\"", shell, args); 1420 execl(shell, shell, "-c", args, (char *)NULL); 1421 error("Couldn't execute %s -c \"%s\": %s", 1422 shell, args, strerror(errno)); 1423 _exit(1); 1424 } else if (pid == -1) 1425 fatal("fork failed: %.100s", strerror(errno)); 1426 while (waitpid(pid, &status, 0) == -1) 1427 if (errno != EINTR) 1428 fatal("Couldn't wait for child: %s", strerror(errno)); 1429 signal(SIGCHLD, osighand); 1430 1431 if (!WIFEXITED(status)) 1432 return (1); 1433 1434 return (WEXITSTATUS(status)); 1435 } 1436