1 /* $OpenBSD: sshconnect.c,v 1.271 2016/01/14 22:56:56 markus 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 18 #include <sys/param.h> /* roundup */ 19 #include <sys/types.h> 20 #include <sys/wait.h> 21 #include <sys/stat.h> 22 #include <sys/socket.h> 23 #ifdef HAVE_SYS_TIME_H 24 # include <sys/time.h> 25 #endif 26 27 #include <netinet/in.h> 28 #include <arpa/inet.h> 29 30 #include <ctype.h> 31 #include <errno.h> 32 #include <fcntl.h> 33 #include <netdb.h> 34 #ifdef HAVE_PATHS_H 35 #include <paths.h> 36 #endif 37 #include <pwd.h> 38 #include <signal.h> 39 #include <stdarg.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include "xmalloc.h" 46 #include "key.h" 47 #include "hostfile.h" 48 #include "ssh.h" 49 #include "rsa.h" 50 #include "buffer.h" 51 #include "packet.h" 52 #include "uidswap.h" 53 #include "compat.h" 54 #include "key.h" 55 #include "sshconnect.h" 56 #include "hostfile.h" 57 #include "log.h" 58 #include "misc.h" 59 #include "readconf.h" 60 #include "atomicio.h" 61 #include "dns.h" 62 #include "monitor_fdpass.h" 63 #include "ssh2.h" 64 #include "version.h" 65 #include "authfile.h" 66 #include "ssherr.h" 67 #include "authfd.h" 68 69 char *client_version_string = NULL; 70 char *server_version_string = NULL; 71 Key *previous_host_key = NULL; 72 73 static int matching_host_key_dns = 0; 74 75 static pid_t proxy_command_pid = 0; 76 77 /* import */ 78 extern Options options; 79 extern char *__progname; 80 extern uid_t original_real_uid; 81 extern uid_t original_effective_uid; 82 83 static int show_other_keys(struct hostkeys *, Key *); 84 static void warn_changed_key(Key *); 85 86 /* Expand a proxy command */ 87 static char * 88 expand_proxy_command(const char *proxy_command, const char *user, 89 const char *host, int port) 90 { 91 char *tmp, *ret, strport[NI_MAXSERV]; 92 93 snprintf(strport, sizeof strport, "%d", port); 94 xasprintf(&tmp, "exec %s", proxy_command); 95 ret = percent_expand(tmp, "h", host, "p", strport, 96 "r", options.user, (char *)NULL); 97 free(tmp); 98 return ret; 99 } 100 101 /* 102 * Connect to the given ssh server using a proxy command that passes a 103 * a connected fd back to us. 104 */ 105 static int 106 ssh_proxy_fdpass_connect(const char *host, u_short port, 107 const char *proxy_command) 108 { 109 char *command_string; 110 int sp[2], sock; 111 pid_t pid; 112 char *shell; 113 114 if ((shell = getenv("SHELL")) == NULL) 115 shell = _PATH_BSHELL; 116 117 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 118 fatal("Could not create socketpair to communicate with " 119 "proxy dialer: %.100s", strerror(errno)); 120 121 command_string = expand_proxy_command(proxy_command, options.user, 122 host, port); 123 debug("Executing proxy dialer command: %.500s", command_string); 124 125 /* Fork and execute the proxy command. */ 126 if ((pid = fork()) == 0) { 127 char *argv[10]; 128 129 /* Child. Permanently give up superuser privileges. */ 130 permanently_drop_suid(original_real_uid); 131 132 close(sp[1]); 133 /* Redirect stdin and stdout. */ 134 if (sp[0] != 0) { 135 if (dup2(sp[0], 0) < 0) 136 perror("dup2 stdin"); 137 } 138 if (sp[0] != 1) { 139 if (dup2(sp[0], 1) < 0) 140 perror("dup2 stdout"); 141 } 142 if (sp[0] >= 2) 143 close(sp[0]); 144 145 /* 146 * Stderr is left as it is so that error messages get 147 * printed on the user's terminal. 148 */ 149 argv[0] = shell; 150 argv[1] = "-c"; 151 argv[2] = command_string; 152 argv[3] = NULL; 153 154 /* 155 * Execute the proxy command. 156 * Note that we gave up any extra privileges above. 157 */ 158 execv(argv[0], argv); 159 perror(argv[0]); 160 exit(1); 161 } 162 /* Parent. */ 163 if (pid < 0) 164 fatal("fork failed: %.100s", strerror(errno)); 165 close(sp[0]); 166 free(command_string); 167 168 if ((sock = mm_receive_fd(sp[1])) == -1) 169 fatal("proxy dialer did not pass back a connection"); 170 close(sp[1]); 171 172 while (waitpid(pid, NULL, 0) == -1) 173 if (errno != EINTR) 174 fatal("Couldn't wait for child: %s", strerror(errno)); 175 176 /* Set the connection file descriptors. */ 177 packet_set_connection(sock, sock); 178 179 return 0; 180 } 181 182 /* 183 * Connect to the given ssh server using a proxy command. 184 */ 185 static int 186 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 187 { 188 char *command_string; 189 int pin[2], pout[2]; 190 pid_t pid; 191 char *shell; 192 193 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 194 shell = _PATH_BSHELL; 195 196 /* Create pipes for communicating with the proxy. */ 197 if (pipe(pin) < 0 || pipe(pout) < 0) 198 fatal("Could not create pipes to communicate with the proxy: %.100s", 199 strerror(errno)); 200 201 command_string = expand_proxy_command(proxy_command, options.user, 202 host, port); 203 debug("Executing proxy command: %.500s", command_string); 204 205 /* Fork and execute the proxy command. */ 206 if ((pid = fork()) == 0) { 207 char *argv[10]; 208 209 /* Child. Permanently give up superuser privileges. */ 210 permanently_drop_suid(original_real_uid); 211 212 /* Redirect stdin and stdout. */ 213 close(pin[1]); 214 if (pin[0] != 0) { 215 if (dup2(pin[0], 0) < 0) 216 perror("dup2 stdin"); 217 close(pin[0]); 218 } 219 close(pout[0]); 220 if (dup2(pout[1], 1) < 0) 221 perror("dup2 stdout"); 222 /* Cannot be 1 because pin allocated two descriptors. */ 223 close(pout[1]); 224 225 /* Stderr is left as it is so that error messages get 226 printed on the user's terminal. */ 227 argv[0] = shell; 228 argv[1] = "-c"; 229 argv[2] = command_string; 230 argv[3] = NULL; 231 232 /* Execute the proxy command. Note that we gave up any 233 extra privileges above. */ 234 signal(SIGPIPE, SIG_DFL); 235 execv(argv[0], argv); 236 perror(argv[0]); 237 exit(1); 238 } 239 /* Parent. */ 240 if (pid < 0) 241 fatal("fork failed: %.100s", strerror(errno)); 242 else 243 proxy_command_pid = pid; /* save pid to clean up later */ 244 245 /* Close child side of the descriptors. */ 246 close(pin[0]); 247 close(pout[1]); 248 249 /* Free the command name. */ 250 free(command_string); 251 252 /* Set the connection file descriptors. */ 253 packet_set_connection(pout[0], pin[1]); 254 255 /* Indicate OK return */ 256 return 0; 257 } 258 259 void 260 ssh_kill_proxy_command(void) 261 { 262 /* 263 * Send SIGHUP to proxy command if used. We don't wait() in 264 * case it hangs and instead rely on init to reap the child 265 */ 266 if (proxy_command_pid > 1) 267 kill(proxy_command_pid, SIGHUP); 268 } 269 270 /* 271 * Creates a (possibly privileged) socket for use as the ssh connection. 272 */ 273 static int 274 ssh_create_socket(int privileged, struct addrinfo *ai) 275 { 276 int sock, r, gaierr; 277 struct addrinfo hints, *res = NULL; 278 279 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 280 if (sock < 0) { 281 error("socket: %s", strerror(errno)); 282 return -1; 283 } 284 fcntl(sock, F_SETFD, FD_CLOEXEC); 285 286 /* Bind the socket to an alternative local IP address */ 287 if (options.bind_address == NULL && !privileged) 288 return sock; 289 290 if (options.bind_address) { 291 memset(&hints, 0, sizeof(hints)); 292 hints.ai_family = ai->ai_family; 293 hints.ai_socktype = ai->ai_socktype; 294 hints.ai_protocol = ai->ai_protocol; 295 hints.ai_flags = AI_PASSIVE; 296 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 297 if (gaierr) { 298 error("getaddrinfo: %s: %s", options.bind_address, 299 ssh_gai_strerror(gaierr)); 300 close(sock); 301 return -1; 302 } 303 } 304 /* 305 * If we are running as root and want to connect to a privileged 306 * port, bind our own socket to a privileged port. 307 */ 308 if (privileged) { 309 PRIV_START; 310 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 311 PRIV_END; 312 if (r < 0) { 313 error("bindresvport_sa: af=%d %s", ai->ai_family, 314 strerror(errno)); 315 goto fail; 316 } 317 } else { 318 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 319 error("bind: %s: %s", options.bind_address, 320 strerror(errno)); 321 fail: 322 close(sock); 323 freeaddrinfo(res); 324 return -1; 325 } 326 } 327 if (res != NULL) 328 freeaddrinfo(res); 329 return sock; 330 } 331 332 static int 333 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 334 socklen_t addrlen, int *timeoutp) 335 { 336 fd_set *fdset; 337 struct timeval tv, t_start; 338 socklen_t optlen; 339 int optval, rc, result = -1; 340 341 gettimeofday(&t_start, NULL); 342 343 if (*timeoutp <= 0) { 344 result = connect(sockfd, serv_addr, addrlen); 345 goto done; 346 } 347 348 set_nonblock(sockfd); 349 rc = connect(sockfd, serv_addr, addrlen); 350 if (rc == 0) { 351 unset_nonblock(sockfd); 352 result = 0; 353 goto done; 354 } 355 if (errno != EINPROGRESS) { 356 result = -1; 357 goto done; 358 } 359 360 fdset = xcalloc(howmany(sockfd + 1, NFDBITS), 361 sizeof(fd_mask)); 362 FD_SET(sockfd, fdset); 363 ms_to_timeval(&tv, *timeoutp); 364 365 for (;;) { 366 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 367 if (rc != -1 || errno != EINTR) 368 break; 369 } 370 371 switch (rc) { 372 case 0: 373 /* Timed out */ 374 errno = ETIMEDOUT; 375 break; 376 case -1: 377 /* Select error */ 378 debug("select: %s", strerror(errno)); 379 break; 380 case 1: 381 /* Completed or failed */ 382 optval = 0; 383 optlen = sizeof(optval); 384 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 385 &optlen) == -1) { 386 debug("getsockopt: %s", strerror(errno)); 387 break; 388 } 389 if (optval != 0) { 390 errno = optval; 391 break; 392 } 393 result = 0; 394 unset_nonblock(sockfd); 395 break; 396 default: 397 /* Should not occur */ 398 fatal("Bogus return (%d) from select()", rc); 399 } 400 401 free(fdset); 402 403 done: 404 if (result == 0 && *timeoutp > 0) { 405 ms_subtract_diff(&t_start, timeoutp); 406 if (*timeoutp <= 0) { 407 errno = ETIMEDOUT; 408 result = -1; 409 } 410 } 411 412 return (result); 413 } 414 415 /* 416 * Opens a TCP/IP connection to the remote server on the given host. 417 * The address of the remote host will be returned in hostaddr. 418 * If port is 0, the default port will be used. If needpriv is true, 419 * a privileged port will be allocated to make the connection. 420 * This requires super-user privileges if needpriv is true. 421 * Connection_attempts specifies the maximum number of tries (one per 422 * second). If proxy_command is non-NULL, it specifies the command (with %h 423 * and %p substituted for host and port, respectively) to use to contact 424 * the daemon. 425 */ 426 static int 427 ssh_connect_direct(const char *host, struct addrinfo *aitop, 428 struct sockaddr_storage *hostaddr, u_short port, int family, 429 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 430 { 431 int on = 1; 432 int sock = -1, attempt; 433 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 434 struct addrinfo *ai; 435 436 debug2("%s: needpriv %d", __func__, needpriv); 437 memset(ntop, 0, sizeof(ntop)); 438 memset(strport, 0, sizeof(strport)); 439 440 for (attempt = 0; attempt < connection_attempts; attempt++) { 441 if (attempt > 0) { 442 /* Sleep a moment before retrying. */ 443 sleep(1); 444 debug("Trying again..."); 445 } 446 /* 447 * Loop through addresses for this host, and try each one in 448 * sequence until the connection succeeds. 449 */ 450 for (ai = aitop; ai; ai = ai->ai_next) { 451 if (ai->ai_family != AF_INET && 452 ai->ai_family != AF_INET6) 453 continue; 454 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 455 ntop, sizeof(ntop), strport, sizeof(strport), 456 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 457 error("%s: getnameinfo failed", __func__); 458 continue; 459 } 460 debug("Connecting to %.200s [%.100s] port %s.", 461 host, ntop, strport); 462 463 /* Create a socket for connecting. */ 464 sock = ssh_create_socket(needpriv, ai); 465 if (sock < 0) 466 /* Any error is already output */ 467 continue; 468 469 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 470 timeout_ms) >= 0) { 471 /* Successful connection. */ 472 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 473 break; 474 } else { 475 debug("connect to address %s port %s: %s", 476 ntop, strport, strerror(errno)); 477 close(sock); 478 sock = -1; 479 } 480 } 481 if (sock != -1) 482 break; /* Successful connection. */ 483 } 484 485 /* Return failure if we didn't get a successful connection. */ 486 if (sock == -1) { 487 error("ssh: connect to host %s port %s: %s", 488 host, strport, strerror(errno)); 489 return (-1); 490 } 491 492 debug("Connection established."); 493 494 /* Set SO_KEEPALIVE if requested. */ 495 if (want_keepalive && 496 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 497 sizeof(on)) < 0) 498 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 499 500 /* Set the connection. */ 501 packet_set_connection(sock, sock); 502 503 return 0; 504 } 505 506 int 507 ssh_connect(const char *host, struct addrinfo *addrs, 508 struct sockaddr_storage *hostaddr, u_short port, int family, 509 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 510 { 511 if (options.proxy_command == NULL) { 512 return ssh_connect_direct(host, addrs, hostaddr, port, family, 513 connection_attempts, timeout_ms, want_keepalive, needpriv); 514 } else if (strcmp(options.proxy_command, "-") == 0) { 515 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 516 return 0; /* Always succeeds */ 517 } else if (options.proxy_use_fdpass) { 518 return ssh_proxy_fdpass_connect(host, port, 519 options.proxy_command); 520 } 521 return ssh_proxy_connect(host, port, options.proxy_command); 522 } 523 524 static void 525 send_client_banner(int connection_out, int minor1) 526 { 527 /* Send our own protocol version identification. */ 528 if (compat20) { 529 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n", 530 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION); 531 } else { 532 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n", 533 PROTOCOL_MAJOR_1, minor1, SSH_VERSION); 534 } 535 if (atomicio(vwrite, connection_out, client_version_string, 536 strlen(client_version_string)) != strlen(client_version_string)) 537 fatal("write: %.100s", strerror(errno)); 538 chop(client_version_string); 539 debug("Local version string %.100s", client_version_string); 540 } 541 542 /* 543 * Waits for the server identification string, and sends our own 544 * identification string. 545 */ 546 void 547 ssh_exchange_identification(int timeout_ms) 548 { 549 char buf[256], remote_version[256]; /* must be same size! */ 550 int remote_major, remote_minor, mismatch; 551 int connection_in = packet_get_connection_in(); 552 int connection_out = packet_get_connection_out(); 553 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 554 u_int i, n; 555 size_t len; 556 int fdsetsz, remaining, rc; 557 struct timeval t_start, t_remaining; 558 fd_set *fdset; 559 560 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 561 fdset = xcalloc(1, fdsetsz); 562 563 /* 564 * If we are SSH2-only then we can send the banner immediately and 565 * save a round-trip. 566 */ 567 if (options.protocol == SSH_PROTO_2) { 568 enable_compat20(); 569 send_client_banner(connection_out, 0); 570 client_banner_sent = 1; 571 } 572 573 /* Read other side's version identification. */ 574 remaining = timeout_ms; 575 for (n = 0;;) { 576 for (i = 0; i < sizeof(buf) - 1; i++) { 577 if (timeout_ms > 0) { 578 gettimeofday(&t_start, NULL); 579 ms_to_timeval(&t_remaining, remaining); 580 FD_SET(connection_in, fdset); 581 rc = select(connection_in + 1, fdset, NULL, 582 fdset, &t_remaining); 583 ms_subtract_diff(&t_start, &remaining); 584 if (rc == 0 || remaining <= 0) 585 fatal("Connection timed out during " 586 "banner exchange"); 587 if (rc == -1) { 588 if (errno == EINTR) 589 continue; 590 fatal("ssh_exchange_identification: " 591 "select: %s", strerror(errno)); 592 } 593 } 594 595 len = atomicio(read, connection_in, &buf[i], 1); 596 597 if (len != 1 && errno == EPIPE) 598 fatal("ssh_exchange_identification: " 599 "Connection closed by remote host"); 600 else if (len != 1) 601 fatal("ssh_exchange_identification: " 602 "read: %.100s", strerror(errno)); 603 if (buf[i] == '\r') { 604 buf[i] = '\n'; 605 buf[i + 1] = 0; 606 continue; /**XXX wait for \n */ 607 } 608 if (buf[i] == '\n') { 609 buf[i + 1] = 0; 610 break; 611 } 612 if (++n > 65536) 613 fatal("ssh_exchange_identification: " 614 "No banner received"); 615 } 616 buf[sizeof(buf) - 1] = 0; 617 if (strncmp(buf, "SSH-", 4) == 0) 618 break; 619 debug("ssh_exchange_identification: %s", buf); 620 } 621 server_version_string = xstrdup(buf); 622 free(fdset); 623 624 /* 625 * Check that the versions match. In future this might accept 626 * several versions and set appropriate flags to handle them. 627 */ 628 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 629 &remote_major, &remote_minor, remote_version) != 3) 630 fatal("Bad remote protocol version identification: '%.100s'", buf); 631 debug("Remote protocol version %d.%d, remote software version %.100s", 632 remote_major, remote_minor, remote_version); 633 634 active_state->compat = compat_datafellows(remote_version); 635 mismatch = 0; 636 637 switch (remote_major) { 638 case 1: 639 if (remote_minor == 99 && 640 (options.protocol & SSH_PROTO_2) && 641 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 642 enable_compat20(); 643 break; 644 } 645 if (!(options.protocol & SSH_PROTO_1)) { 646 mismatch = 1; 647 break; 648 } 649 if (remote_minor < 3) { 650 fatal("Remote machine has too old SSH software version."); 651 } else if (remote_minor == 3 || remote_minor == 4) { 652 /* We speak 1.3, too. */ 653 enable_compat13(); 654 minor1 = 3; 655 if (options.forward_agent) { 656 logit("Agent forwarding disabled for protocol 1.3"); 657 options.forward_agent = 0; 658 } 659 } 660 break; 661 case 2: 662 if (options.protocol & SSH_PROTO_2) { 663 enable_compat20(); 664 break; 665 } 666 /* FALLTHROUGH */ 667 default: 668 mismatch = 1; 669 break; 670 } 671 if (mismatch) 672 fatal("Protocol major versions differ: %d vs. %d", 673 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 674 remote_major); 675 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 676 fatal("Server version \"%.100s\" uses unsafe key agreement; " 677 "refusing connection", remote_version); 678 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 679 logit("Server version \"%.100s\" uses unsafe RSA signature " 680 "scheme; disabling use of RSA keys", remote_version); 681 if (!client_banner_sent) 682 send_client_banner(connection_out, minor1); 683 chop(server_version_string); 684 } 685 686 /* defaults to 'no' */ 687 static int 688 confirm(const char *prompt) 689 { 690 const char *msg, *again = "Please type 'yes' or 'no': "; 691 char *p; 692 int ret = -1; 693 694 if (options.batch_mode) 695 return 0; 696 for (msg = prompt;;msg = again) { 697 p = read_passphrase(msg, RP_ECHO); 698 if (p == NULL || 699 (p[0] == '\0') || (p[0] == '\n') || 700 strncasecmp(p, "no", 2) == 0) 701 ret = 0; 702 if (p && strncasecmp(p, "yes", 3) == 0) 703 ret = 1; 704 free(p); 705 if (ret != -1) 706 return ret; 707 } 708 } 709 710 static int 711 check_host_cert(const char *host, const Key *host_key) 712 { 713 const char *reason; 714 715 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 716 error("%s", reason); 717 return 0; 718 } 719 if (buffer_len(host_key->cert->critical) != 0) { 720 error("Certificate for %s contains unsupported " 721 "critical options(s)", host); 722 return 0; 723 } 724 return 1; 725 } 726 727 static int 728 sockaddr_is_local(struct sockaddr *hostaddr) 729 { 730 switch (hostaddr->sa_family) { 731 case AF_INET: 732 return (ntohl(((struct sockaddr_in *)hostaddr)-> 733 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 734 case AF_INET6: 735 return IN6_IS_ADDR_LOOPBACK( 736 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 737 default: 738 return 0; 739 } 740 } 741 742 /* 743 * Prepare the hostname and ip address strings that are used to lookup 744 * host keys in known_hosts files. These may have a port number appended. 745 */ 746 void 747 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 748 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 749 { 750 char ntop[NI_MAXHOST]; 751 socklen_t addrlen; 752 753 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 754 case -1: 755 addrlen = 0; 756 break; 757 case AF_INET: 758 addrlen = sizeof(struct sockaddr_in); 759 break; 760 case AF_INET6: 761 addrlen = sizeof(struct sockaddr_in6); 762 break; 763 default: 764 addrlen = sizeof(struct sockaddr); 765 break; 766 } 767 768 /* 769 * We don't have the remote ip-address for connections 770 * using a proxy command 771 */ 772 if (hostfile_ipaddr != NULL) { 773 if (options.proxy_command == NULL) { 774 if (getnameinfo(hostaddr, addrlen, 775 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 776 fatal("%s: getnameinfo failed", __func__); 777 *hostfile_ipaddr = put_host_port(ntop, port); 778 } else { 779 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 780 "command>"); 781 } 782 } 783 784 /* 785 * Allow the user to record the key under a different name or 786 * differentiate a non-standard port. This is useful for ssh 787 * tunneling over forwarded connections or if you run multiple 788 * sshd's on different ports on the same machine. 789 */ 790 if (hostfile_hostname != NULL) { 791 if (options.host_key_alias != NULL) { 792 *hostfile_hostname = xstrdup(options.host_key_alias); 793 debug("using hostkeyalias: %s", *hostfile_hostname); 794 } else { 795 *hostfile_hostname = put_host_port(hostname, port); 796 } 797 } 798 } 799 800 /* 801 * check whether the supplied host key is valid, return -1 if the key 802 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 803 */ 804 #define RDRW 0 805 #define RDONLY 1 806 #define ROQUIET 2 807 static int 808 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 809 Key *host_key, int readonly, 810 char **user_hostfiles, u_int num_user_hostfiles, 811 char **system_hostfiles, u_int num_system_hostfiles) 812 { 813 HostStatus host_status; 814 HostStatus ip_status; 815 Key *raw_key = NULL; 816 char *ip = NULL, *host = NULL; 817 char hostline[1000], *hostp, *fp, *ra; 818 char msg[1024]; 819 const char *type; 820 const struct hostkey_entry *host_found, *ip_found; 821 int len, cancelled_forwarding = 0; 822 int local = sockaddr_is_local(hostaddr); 823 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 824 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 825 struct hostkeys *host_hostkeys, *ip_hostkeys; 826 u_int i; 827 828 /* 829 * Force accepting of the host key for loopback/localhost. The 830 * problem is that if the home directory is NFS-mounted to multiple 831 * machines, localhost will refer to a different machine in each of 832 * them, and the user will get bogus HOST_CHANGED warnings. This 833 * essentially disables host authentication for localhost; however, 834 * this is probably not a real problem. 835 */ 836 if (options.no_host_authentication_for_localhost == 1 && local && 837 options.host_key_alias == NULL) { 838 debug("Forcing accepting of host key for " 839 "loopback/localhost."); 840 return 0; 841 } 842 843 /* 844 * Prepare the hostname and address strings used for hostkey lookup. 845 * In some cases, these will have a port number appended. 846 */ 847 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 848 849 /* 850 * Turn off check_host_ip if the connection is to localhost, via proxy 851 * command or if we don't have a hostname to compare with 852 */ 853 if (options.check_host_ip && (local || 854 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 855 options.check_host_ip = 0; 856 857 host_hostkeys = init_hostkeys(); 858 for (i = 0; i < num_user_hostfiles; i++) 859 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 860 for (i = 0; i < num_system_hostfiles; i++) 861 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 862 863 ip_hostkeys = NULL; 864 if (!want_cert && options.check_host_ip) { 865 ip_hostkeys = init_hostkeys(); 866 for (i = 0; i < num_user_hostfiles; i++) 867 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 868 for (i = 0; i < num_system_hostfiles; i++) 869 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 870 } 871 872 retry: 873 /* Reload these as they may have changed on cert->key downgrade */ 874 want_cert = key_is_cert(host_key); 875 type = key_type(host_key); 876 877 /* 878 * Check if the host key is present in the user's list of known 879 * hosts or in the systemwide list. 880 */ 881 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 882 &host_found); 883 884 /* 885 * Also perform check for the ip address, skip the check if we are 886 * localhost, looking for a certificate, or the hostname was an ip 887 * address to begin with. 888 */ 889 if (!want_cert && ip_hostkeys != NULL) { 890 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 891 &ip_found); 892 if (host_status == HOST_CHANGED && 893 (ip_status != HOST_CHANGED || 894 (ip_found != NULL && 895 !key_equal(ip_found->key, host_found->key)))) 896 host_ip_differ = 1; 897 } else 898 ip_status = host_status; 899 900 switch (host_status) { 901 case HOST_OK: 902 /* The host is known and the key matches. */ 903 debug("Host '%.200s' is known and matches the %s host %s.", 904 host, type, want_cert ? "certificate" : "key"); 905 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 906 host_found->file, host_found->line); 907 if (want_cert && !check_host_cert(hostname, host_key)) 908 goto fail; 909 if (options.check_host_ip && ip_status == HOST_NEW) { 910 if (readonly || want_cert) 911 logit("%s host key for IP address " 912 "'%.128s' not in list of known hosts.", 913 type, ip); 914 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 915 host_key, options.hash_known_hosts)) 916 logit("Failed to add the %s host key for IP " 917 "address '%.128s' to the list of known " 918 "hosts (%.500s).", type, ip, 919 user_hostfiles[0]); 920 else 921 logit("Warning: Permanently added the %s host " 922 "key for IP address '%.128s' to the list " 923 "of known hosts.", type, ip); 924 } else if (options.visual_host_key) { 925 fp = sshkey_fingerprint(host_key, 926 options.fingerprint_hash, SSH_FP_DEFAULT); 927 ra = sshkey_fingerprint(host_key, 928 options.fingerprint_hash, SSH_FP_RANDOMART); 929 if (fp == NULL || ra == NULL) 930 fatal("%s: sshkey_fingerprint fail", __func__); 931 logit("Host key fingerprint is %s\n%s", fp, ra); 932 free(ra); 933 free(fp); 934 } 935 hostkey_trusted = 1; 936 break; 937 case HOST_NEW: 938 if (options.host_key_alias == NULL && port != 0 && 939 port != SSH_DEFAULT_PORT) { 940 debug("checking without port identifier"); 941 if (check_host_key(hostname, hostaddr, 0, host_key, 942 ROQUIET, user_hostfiles, num_user_hostfiles, 943 system_hostfiles, num_system_hostfiles) == 0) { 944 debug("found matching key w/out port"); 945 break; 946 } 947 } 948 if (readonly || want_cert) 949 goto fail; 950 /* The host is new. */ 951 if (options.strict_host_key_checking == 1) { 952 /* 953 * User has requested strict host key checking. We 954 * will not add the host key automatically. The only 955 * alternative left is to abort. 956 */ 957 error("No %s host key is known for %.200s and you " 958 "have requested strict checking.", type, host); 959 goto fail; 960 } else if (options.strict_host_key_checking == 2) { 961 char msg1[1024], msg2[1024]; 962 963 if (show_other_keys(host_hostkeys, host_key)) 964 snprintf(msg1, sizeof(msg1), 965 "\nbut keys of different type are already" 966 " known for this host."); 967 else 968 snprintf(msg1, sizeof(msg1), "."); 969 /* The default */ 970 fp = sshkey_fingerprint(host_key, 971 options.fingerprint_hash, SSH_FP_DEFAULT); 972 ra = sshkey_fingerprint(host_key, 973 options.fingerprint_hash, SSH_FP_RANDOMART); 974 if (fp == NULL || ra == NULL) 975 fatal("%s: sshkey_fingerprint fail", __func__); 976 msg2[0] = '\0'; 977 if (options.verify_host_key_dns) { 978 if (matching_host_key_dns) 979 snprintf(msg2, sizeof(msg2), 980 "Matching host key fingerprint" 981 " found in DNS.\n"); 982 else 983 snprintf(msg2, sizeof(msg2), 984 "No matching host key fingerprint" 985 " found in DNS.\n"); 986 } 987 snprintf(msg, sizeof(msg), 988 "The authenticity of host '%.200s (%s)' can't be " 989 "established%s\n" 990 "%s key fingerprint is %s.%s%s\n%s" 991 "Are you sure you want to continue connecting " 992 "(yes/no)? ", 993 host, ip, msg1, type, fp, 994 options.visual_host_key ? "\n" : "", 995 options.visual_host_key ? ra : "", 996 msg2); 997 free(ra); 998 free(fp); 999 if (!confirm(msg)) 1000 goto fail; 1001 hostkey_trusted = 1; /* user explicitly confirmed */ 1002 } 1003 /* 1004 * If not in strict mode, add the key automatically to the 1005 * local known_hosts file. 1006 */ 1007 if (options.check_host_ip && ip_status == HOST_NEW) { 1008 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 1009 hostp = hostline; 1010 if (options.hash_known_hosts) { 1011 /* Add hash of host and IP separately */ 1012 r = add_host_to_hostfile(user_hostfiles[0], 1013 host, host_key, options.hash_known_hosts) && 1014 add_host_to_hostfile(user_hostfiles[0], ip, 1015 host_key, options.hash_known_hosts); 1016 } else { 1017 /* Add unhashed "host,ip" */ 1018 r = add_host_to_hostfile(user_hostfiles[0], 1019 hostline, host_key, 1020 options.hash_known_hosts); 1021 } 1022 } else { 1023 r = add_host_to_hostfile(user_hostfiles[0], host, 1024 host_key, options.hash_known_hosts); 1025 hostp = host; 1026 } 1027 1028 if (!r) 1029 logit("Failed to add the host to the list of known " 1030 "hosts (%.500s).", user_hostfiles[0]); 1031 else 1032 logit("Warning: Permanently added '%.200s' (%s) to the " 1033 "list of known hosts.", hostp, type); 1034 break; 1035 case HOST_REVOKED: 1036 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1037 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1038 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1039 error("The %s host key for %s is marked as revoked.", type, host); 1040 error("This could mean that a stolen key is being used to"); 1041 error("impersonate this host."); 1042 1043 /* 1044 * If strict host key checking is in use, the user will have 1045 * to edit the key manually and we can only abort. 1046 */ 1047 if (options.strict_host_key_checking) { 1048 error("%s host key for %.200s was revoked and you have " 1049 "requested strict checking.", type, host); 1050 goto fail; 1051 } 1052 goto continue_unsafe; 1053 1054 case HOST_CHANGED: 1055 if (want_cert) { 1056 /* 1057 * This is only a debug() since it is valid to have 1058 * CAs with wildcard DNS matches that don't match 1059 * all hosts that one might visit. 1060 */ 1061 debug("Host certificate authority does not " 1062 "match %s in %s:%lu", CA_MARKER, 1063 host_found->file, host_found->line); 1064 goto fail; 1065 } 1066 if (readonly == ROQUIET) 1067 goto fail; 1068 if (options.check_host_ip && host_ip_differ) { 1069 char *key_msg; 1070 if (ip_status == HOST_NEW) 1071 key_msg = "is unknown"; 1072 else if (ip_status == HOST_OK) 1073 key_msg = "is unchanged"; 1074 else 1075 key_msg = "has a different value"; 1076 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1077 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1078 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1079 error("The %s host key for %s has changed,", type, host); 1080 error("and the key for the corresponding IP address %s", ip); 1081 error("%s. This could either mean that", key_msg); 1082 error("DNS SPOOFING is happening or the IP address for the host"); 1083 error("and its host key have changed at the same time."); 1084 if (ip_status != HOST_NEW) 1085 error("Offending key for IP in %s:%lu", 1086 ip_found->file, ip_found->line); 1087 } 1088 /* The host key has changed. */ 1089 warn_changed_key(host_key); 1090 error("Add correct host key in %.100s to get rid of this message.", 1091 user_hostfiles[0]); 1092 error("Offending %s key in %s:%lu", key_type(host_found->key), 1093 host_found->file, host_found->line); 1094 1095 /* 1096 * If strict host key checking is in use, the user will have 1097 * to edit the key manually and we can only abort. 1098 */ 1099 if (options.strict_host_key_checking) { 1100 error("%s host key for %.200s has changed and you have " 1101 "requested strict checking.", type, host); 1102 goto fail; 1103 } 1104 1105 continue_unsafe: 1106 /* 1107 * If strict host key checking has not been requested, allow 1108 * the connection but without MITM-able authentication or 1109 * forwarding. 1110 */ 1111 if (options.password_authentication) { 1112 error("Password authentication is disabled to avoid " 1113 "man-in-the-middle attacks."); 1114 options.password_authentication = 0; 1115 cancelled_forwarding = 1; 1116 } 1117 if (options.kbd_interactive_authentication) { 1118 error("Keyboard-interactive authentication is disabled" 1119 " to avoid man-in-the-middle attacks."); 1120 options.kbd_interactive_authentication = 0; 1121 options.challenge_response_authentication = 0; 1122 cancelled_forwarding = 1; 1123 } 1124 if (options.challenge_response_authentication) { 1125 error("Challenge/response authentication is disabled" 1126 " to avoid man-in-the-middle attacks."); 1127 options.challenge_response_authentication = 0; 1128 cancelled_forwarding = 1; 1129 } 1130 if (options.forward_agent) { 1131 error("Agent forwarding is disabled to avoid " 1132 "man-in-the-middle attacks."); 1133 options.forward_agent = 0; 1134 cancelled_forwarding = 1; 1135 } 1136 if (options.forward_x11) { 1137 error("X11 forwarding is disabled to avoid " 1138 "man-in-the-middle attacks."); 1139 options.forward_x11 = 0; 1140 cancelled_forwarding = 1; 1141 } 1142 if (options.num_local_forwards > 0 || 1143 options.num_remote_forwards > 0) { 1144 error("Port forwarding is disabled to avoid " 1145 "man-in-the-middle attacks."); 1146 options.num_local_forwards = 1147 options.num_remote_forwards = 0; 1148 cancelled_forwarding = 1; 1149 } 1150 if (options.tun_open != SSH_TUNMODE_NO) { 1151 error("Tunnel forwarding is disabled to avoid " 1152 "man-in-the-middle attacks."); 1153 options.tun_open = SSH_TUNMODE_NO; 1154 cancelled_forwarding = 1; 1155 } 1156 if (options.exit_on_forward_failure && cancelled_forwarding) 1157 fatal("Error: forwarding disabled due to host key " 1158 "check failure"); 1159 1160 /* 1161 * XXX Should permit the user to change to use the new id. 1162 * This could be done by converting the host key to an 1163 * identifying sentence, tell that the host identifies itself 1164 * by that sentence, and ask the user if he/she wishes to 1165 * accept the authentication. 1166 */ 1167 break; 1168 case HOST_FOUND: 1169 fatal("internal error"); 1170 break; 1171 } 1172 1173 if (options.check_host_ip && host_status != HOST_CHANGED && 1174 ip_status == HOST_CHANGED) { 1175 snprintf(msg, sizeof(msg), 1176 "Warning: the %s host key for '%.200s' " 1177 "differs from the key for the IP address '%.128s'" 1178 "\nOffending key for IP in %s:%lu", 1179 type, host, ip, ip_found->file, ip_found->line); 1180 if (host_status == HOST_OK) { 1181 len = strlen(msg); 1182 snprintf(msg + len, sizeof(msg) - len, 1183 "\nMatching host key in %s:%lu", 1184 host_found->file, host_found->line); 1185 } 1186 if (options.strict_host_key_checking == 1) { 1187 logit("%s", msg); 1188 error("Exiting, you have requested strict checking."); 1189 goto fail; 1190 } else if (options.strict_host_key_checking == 2) { 1191 strlcat(msg, "\nAre you sure you want " 1192 "to continue connecting (yes/no)? ", sizeof(msg)); 1193 if (!confirm(msg)) 1194 goto fail; 1195 } else { 1196 logit("%s", msg); 1197 } 1198 } 1199 1200 if (!hostkey_trusted && options.update_hostkeys) { 1201 debug("%s: hostkey not known or explicitly trusted: " 1202 "disabling UpdateHostkeys", __func__); 1203 options.update_hostkeys = 0; 1204 } 1205 1206 free(ip); 1207 free(host); 1208 if (host_hostkeys != NULL) 1209 free_hostkeys(host_hostkeys); 1210 if (ip_hostkeys != NULL) 1211 free_hostkeys(ip_hostkeys); 1212 return 0; 1213 1214 fail: 1215 if (want_cert && host_status != HOST_REVOKED) { 1216 /* 1217 * No matching certificate. Downgrade cert to raw key and 1218 * search normally. 1219 */ 1220 debug("No matching CA found. Retry with plain key"); 1221 raw_key = key_from_private(host_key); 1222 if (key_drop_cert(raw_key) != 0) 1223 fatal("Couldn't drop certificate"); 1224 host_key = raw_key; 1225 goto retry; 1226 } 1227 if (raw_key != NULL) 1228 key_free(raw_key); 1229 free(ip); 1230 free(host); 1231 if (host_hostkeys != NULL) 1232 free_hostkeys(host_hostkeys); 1233 if (ip_hostkeys != NULL) 1234 free_hostkeys(ip_hostkeys); 1235 return -1; 1236 } 1237 1238 /* returns 0 if key verifies or -1 if key does NOT verify */ 1239 int 1240 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1241 { 1242 u_int i; 1243 int r = -1, flags = 0; 1244 char valid[64], *fp = NULL, *cafp = NULL; 1245 struct sshkey *plain = NULL; 1246 1247 if ((fp = sshkey_fingerprint(host_key, 1248 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1249 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1250 r = -1; 1251 goto out; 1252 } 1253 1254 if (sshkey_is_cert(host_key)) { 1255 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1256 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1257 error("%s: fingerprint CA key: %s", 1258 __func__, ssh_err(r)); 1259 r = -1; 1260 goto out; 1261 } 1262 sshkey_format_cert_validity(host_key->cert, 1263 valid, sizeof(valid)); 1264 debug("Server host certificate: %s %s, serial %llu " 1265 "ID \"%s\" CA %s %s valid %s", 1266 sshkey_ssh_name(host_key), fp, 1267 (unsigned long long)host_key->cert->serial, 1268 host_key->cert->key_id, 1269 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1270 valid); 1271 for (i = 0; i < host_key->cert->nprincipals; i++) { 1272 debug2("Server host certificate hostname: %s", 1273 host_key->cert->principals[i]); 1274 } 1275 } else { 1276 debug("Server host key: %s %s", compat20 ? 1277 sshkey_ssh_name(host_key) : sshkey_type(host_key), fp); 1278 } 1279 1280 if (sshkey_equal(previous_host_key, host_key)) { 1281 debug2("%s: server host key %s %s matches cached key", 1282 __func__, sshkey_type(host_key), fp); 1283 r = 0; 1284 goto out; 1285 } 1286 1287 /* Check in RevokedHostKeys file if specified */ 1288 if (options.revoked_host_keys != NULL) { 1289 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1290 switch (r) { 1291 case 0: 1292 break; /* not revoked */ 1293 case SSH_ERR_KEY_REVOKED: 1294 error("Host key %s %s revoked by file %s", 1295 sshkey_type(host_key), fp, 1296 options.revoked_host_keys); 1297 r = -1; 1298 goto out; 1299 default: 1300 error("Error checking host key %s %s in " 1301 "revoked keys file %s: %s", sshkey_type(host_key), 1302 fp, options.revoked_host_keys, ssh_err(r)); 1303 r = -1; 1304 goto out; 1305 } 1306 } 1307 1308 if (options.verify_host_key_dns) { 1309 /* 1310 * XXX certs are not yet supported for DNS, so downgrade 1311 * them and try the plain key. 1312 */ 1313 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1314 goto out; 1315 if (sshkey_is_cert(plain)) 1316 sshkey_drop_cert(plain); 1317 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1318 if (flags & DNS_VERIFY_FOUND) { 1319 if (options.verify_host_key_dns == 1 && 1320 flags & DNS_VERIFY_MATCH && 1321 flags & DNS_VERIFY_SECURE) { 1322 r = 0; 1323 goto out; 1324 } 1325 if (flags & DNS_VERIFY_MATCH) { 1326 matching_host_key_dns = 1; 1327 } else { 1328 warn_changed_key(plain); 1329 error("Update the SSHFP RR in DNS " 1330 "with the new host key to get rid " 1331 "of this message."); 1332 } 1333 } 1334 } 1335 } 1336 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1337 options.user_hostfiles, options.num_user_hostfiles, 1338 options.system_hostfiles, options.num_system_hostfiles); 1339 1340 out: 1341 sshkey_free(plain); 1342 free(fp); 1343 free(cafp); 1344 if (r == 0 && host_key != NULL) { 1345 key_free(previous_host_key); 1346 previous_host_key = key_from_private(host_key); 1347 } 1348 1349 return r; 1350 } 1351 1352 /* 1353 * Starts a dialog with the server, and authenticates the current user on the 1354 * server. This does not need any extra privileges. The basic connection 1355 * to the server must already have been established before this is called. 1356 * If login fails, this function prints an error and never returns. 1357 * This function does not require super-user privileges. 1358 */ 1359 void 1360 ssh_login(Sensitive *sensitive, const char *orighost, 1361 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1362 { 1363 char *host; 1364 char *server_user, *local_user; 1365 1366 local_user = xstrdup(pw->pw_name); 1367 server_user = options.user ? options.user : local_user; 1368 1369 /* Convert the user-supplied hostname into all lowercase. */ 1370 host = xstrdup(orighost); 1371 lowercase(host); 1372 1373 /* Exchange protocol version identification strings with the server. */ 1374 ssh_exchange_identification(timeout_ms); 1375 1376 /* Put the connection into non-blocking mode. */ 1377 packet_set_nonblocking(); 1378 1379 /* key exchange */ 1380 /* authenticate user */ 1381 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1382 if (compat20) { 1383 ssh_kex2(host, hostaddr, port); 1384 ssh_userauth2(local_user, server_user, host, sensitive); 1385 } else { 1386 #ifdef WITH_SSH1 1387 ssh_kex(host, hostaddr); 1388 ssh_userauth1(local_user, server_user, host, sensitive); 1389 #else 1390 fatal("ssh1 is not supported"); 1391 #endif 1392 } 1393 free(local_user); 1394 } 1395 1396 void 1397 ssh_put_password(char *password) 1398 { 1399 int size; 1400 char *padded; 1401 1402 if (datafellows & SSH_BUG_PASSWORDPAD) { 1403 packet_put_cstring(password); 1404 return; 1405 } 1406 size = roundup(strlen(password) + 1, 32); 1407 padded = xcalloc(1, size); 1408 strlcpy(padded, password, size); 1409 packet_put_string(padded, size); 1410 explicit_bzero(padded, size); 1411 free(padded); 1412 } 1413 1414 /* print all known host keys for a given host, but skip keys of given type */ 1415 static int 1416 show_other_keys(struct hostkeys *hostkeys, Key *key) 1417 { 1418 int type[] = { 1419 KEY_RSA1, 1420 KEY_RSA, 1421 KEY_DSA, 1422 KEY_ECDSA, 1423 KEY_ED25519, 1424 -1 1425 }; 1426 int i, ret = 0; 1427 char *fp, *ra; 1428 const struct hostkey_entry *found; 1429 1430 for (i = 0; type[i] != -1; i++) { 1431 if (type[i] == key->type) 1432 continue; 1433 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1434 continue; 1435 fp = sshkey_fingerprint(found->key, 1436 options.fingerprint_hash, SSH_FP_DEFAULT); 1437 ra = sshkey_fingerprint(found->key, 1438 options.fingerprint_hash, SSH_FP_RANDOMART); 1439 if (fp == NULL || ra == NULL) 1440 fatal("%s: sshkey_fingerprint fail", __func__); 1441 logit("WARNING: %s key found for host %s\n" 1442 "in %s:%lu\n" 1443 "%s key fingerprint %s.", 1444 key_type(found->key), 1445 found->host, found->file, found->line, 1446 key_type(found->key), fp); 1447 if (options.visual_host_key) 1448 logit("%s", ra); 1449 free(ra); 1450 free(fp); 1451 ret = 1; 1452 } 1453 return ret; 1454 } 1455 1456 static void 1457 warn_changed_key(Key *host_key) 1458 { 1459 char *fp; 1460 1461 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1462 SSH_FP_DEFAULT); 1463 if (fp == NULL) 1464 fatal("%s: sshkey_fingerprint fail", __func__); 1465 1466 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1467 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1468 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1469 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1470 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1471 error("It is also possible that a host key has just been changed."); 1472 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1473 key_type(host_key), fp); 1474 error("Please contact your system administrator."); 1475 1476 free(fp); 1477 } 1478 1479 /* 1480 * Execute a local command 1481 */ 1482 int 1483 ssh_local_cmd(const char *args) 1484 { 1485 char *shell; 1486 pid_t pid; 1487 int status; 1488 void (*osighand)(int); 1489 1490 if (!options.permit_local_command || 1491 args == NULL || !*args) 1492 return (1); 1493 1494 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1495 shell = _PATH_BSHELL; 1496 1497 osighand = signal(SIGCHLD, SIG_DFL); 1498 pid = fork(); 1499 if (pid == 0) { 1500 signal(SIGPIPE, SIG_DFL); 1501 debug3("Executing %s -c \"%s\"", shell, args); 1502 execl(shell, shell, "-c", args, (char *)NULL); 1503 error("Couldn't execute %s -c \"%s\": %s", 1504 shell, args, strerror(errno)); 1505 _exit(1); 1506 } else if (pid == -1) 1507 fatal("fork failed: %.100s", strerror(errno)); 1508 while (waitpid(pid, &status, 0) == -1) 1509 if (errno != EINTR) 1510 fatal("Couldn't wait for child: %s", strerror(errno)); 1511 signal(SIGCHLD, osighand); 1512 1513 if (!WIFEXITED(status)) 1514 return (1); 1515 1516 return (WEXITSTATUS(status)); 1517 } 1518 1519 void 1520 maybe_add_key_to_agent(char *authfile, Key *private, char *comment, 1521 char *passphrase) 1522 { 1523 int auth_sock = -1, r; 1524 1525 if (options.add_keys_to_agent == 0) 1526 return; 1527 1528 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1529 debug3("no authentication agent, not adding key"); 1530 return; 1531 } 1532 1533 if (options.add_keys_to_agent == 2 && 1534 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1535 debug3("user denied adding this key"); 1536 return; 1537 } 1538 1539 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0, 1540 (options.add_keys_to_agent == 3))) == 0) 1541 debug("identity added to agent: %s", authfile); 1542 else 1543 debug("could not add identity to agent: %s (%d)", authfile, r); 1544 } 1545