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 #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 "monitor_fdpass.h" 64 #include "ssh2.h" 65 #include "version.h" 66 #include "authfile.h" 67 #include "ssherr.h" 68 #include "authfd.h" 69 70 char *client_version_string = NULL; 71 char *server_version_string = NULL; 72 Key *previous_host_key = NULL; 73 74 static int matching_host_key_dns = 0; 75 76 static pid_t proxy_command_pid = 0; 77 78 /* import */ 79 extern Options options; 80 extern char *__progname; 81 extern uid_t original_real_uid; 82 extern uid_t original_effective_uid; 83 84 static int show_other_keys(struct hostkeys *, Key *); 85 static void warn_changed_key(Key *); 86 87 /* Expand a proxy command */ 88 static char * 89 expand_proxy_command(const char *proxy_command, const char *user, 90 const char *host, int port) 91 { 92 char *tmp, *ret, strport[NI_MAXSERV]; 93 94 snprintf(strport, sizeof strport, "%d", port); 95 xasprintf(&tmp, "exec %s", proxy_command); 96 ret = percent_expand(tmp, "h", host, "p", strport, 97 "r", options.user, (char *)NULL); 98 free(tmp); 99 return ret; 100 } 101 102 /* 103 * Connect to the given ssh server using a proxy command that passes a 104 * a connected fd back to us. 105 */ 106 static int 107 ssh_proxy_fdpass_connect(const char *host, u_short port, 108 const char *proxy_command) 109 { 110 char *command_string; 111 int sp[2], sock; 112 pid_t pid; 113 char *shell; 114 115 if ((shell = getenv("SHELL")) == NULL) 116 shell = _PATH_BSHELL; 117 118 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 119 fatal("Could not create socketpair to communicate with " 120 "proxy dialer: %.100s", strerror(errno)); 121 122 command_string = expand_proxy_command(proxy_command, options.user, 123 host, port); 124 debug("Executing proxy dialer command: %.500s", command_string); 125 126 /* Fork and execute the proxy command. */ 127 if ((pid = fork()) == 0) { 128 char *argv[10]; 129 130 /* Child. Permanently give up superuser privileges. */ 131 permanently_drop_suid(original_real_uid); 132 133 close(sp[1]); 134 /* Redirect stdin and stdout. */ 135 if (sp[0] != 0) { 136 if (dup2(sp[0], 0) < 0) 137 perror("dup2 stdin"); 138 } 139 if (sp[0] != 1) { 140 if (dup2(sp[0], 1) < 0) 141 perror("dup2 stdout"); 142 } 143 if (sp[0] >= 2) 144 close(sp[0]); 145 146 /* 147 * Stderr is left as it is so that error messages get 148 * printed on the user's terminal. 149 */ 150 argv[0] = shell; 151 argv[1] = "-c"; 152 argv[2] = command_string; 153 argv[3] = NULL; 154 155 /* 156 * Execute the proxy command. 157 * Note that we gave up any extra privileges above. 158 */ 159 execv(argv[0], argv); 160 perror(argv[0]); 161 exit(1); 162 } 163 /* Parent. */ 164 if (pid < 0) 165 fatal("fork failed: %.100s", strerror(errno)); 166 close(sp[0]); 167 free(command_string); 168 169 if ((sock = mm_receive_fd(sp[1])) == -1) 170 fatal("proxy dialer did not pass back a connection"); 171 close(sp[1]); 172 173 while (waitpid(pid, NULL, 0) == -1) 174 if (errno != EINTR) 175 fatal("Couldn't wait for child: %s", strerror(errno)); 176 177 /* Set the connection file descriptors. */ 178 packet_set_connection(sock, sock); 179 180 return 0; 181 } 182 183 /* 184 * Connect to the given ssh server using a proxy command. 185 */ 186 static int 187 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 188 { 189 char *command_string; 190 int pin[2], pout[2]; 191 pid_t pid; 192 char *shell; 193 194 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 195 shell = _PATH_BSHELL; 196 197 /* Create pipes for communicating with the proxy. */ 198 if (pipe(pin) < 0 || pipe(pout) < 0) 199 fatal("Could not create pipes to communicate with the proxy: %.100s", 200 strerror(errno)); 201 202 command_string = expand_proxy_command(proxy_command, options.user, 203 host, port); 204 debug("Executing proxy command: %.500s", command_string); 205 206 /* Fork and execute the proxy command. */ 207 if ((pid = fork()) == 0) { 208 char *argv[10]; 209 210 /* Child. Permanently give up superuser privileges. */ 211 permanently_drop_suid(original_real_uid); 212 213 /* Redirect stdin and stdout. */ 214 close(pin[1]); 215 if (pin[0] != 0) { 216 if (dup2(pin[0], 0) < 0) 217 perror("dup2 stdin"); 218 close(pin[0]); 219 } 220 close(pout[0]); 221 if (dup2(pout[1], 1) < 0) 222 perror("dup2 stdout"); 223 /* Cannot be 1 because pin allocated two descriptors. */ 224 close(pout[1]); 225 226 /* Stderr is left as it is so that error messages get 227 printed on the user's terminal. */ 228 argv[0] = shell; 229 argv[1] = "-c"; 230 argv[2] = command_string; 231 argv[3] = NULL; 232 233 /* Execute the proxy command. Note that we gave up any 234 extra privileges above. */ 235 signal(SIGPIPE, SIG_DFL); 236 execv(argv[0], argv); 237 perror(argv[0]); 238 exit(1); 239 } 240 /* Parent. */ 241 if (pid < 0) 242 fatal("fork failed: %.100s", strerror(errno)); 243 else 244 proxy_command_pid = pid; /* save pid to clean up later */ 245 246 /* Close child side of the descriptors. */ 247 close(pin[0]); 248 close(pout[1]); 249 250 /* Free the command name. */ 251 free(command_string); 252 253 /* Set the connection file descriptors. */ 254 packet_set_connection(pout[0], pin[1]); 255 256 /* Indicate OK return */ 257 return 0; 258 } 259 260 void 261 ssh_kill_proxy_command(void) 262 { 263 /* 264 * Send SIGHUP to proxy command if used. We don't wait() in 265 * case it hangs and instead rely on init to reap the child 266 */ 267 if (proxy_command_pid > 1) 268 kill(proxy_command_pid, SIGHUP); 269 } 270 271 /* 272 * Creates a (possibly privileged) socket for use as the ssh connection. 273 */ 274 static int 275 ssh_create_socket(int privileged, struct addrinfo *ai) 276 { 277 int sock, r, gaierr; 278 struct addrinfo hints, *res = NULL; 279 280 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 281 if (sock < 0) { 282 error("socket: %s", strerror(errno)); 283 return -1; 284 } 285 fcntl(sock, F_SETFD, FD_CLOEXEC); 286 287 /* Bind the socket to an alternative local IP address */ 288 if (options.bind_address == NULL && !privileged) 289 return sock; 290 291 if (options.bind_address) { 292 memset(&hints, 0, sizeof(hints)); 293 hints.ai_family = ai->ai_family; 294 hints.ai_socktype = ai->ai_socktype; 295 hints.ai_protocol = ai->ai_protocol; 296 hints.ai_flags = AI_PASSIVE; 297 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 298 if (gaierr) { 299 error("getaddrinfo: %s: %s", options.bind_address, 300 ssh_gai_strerror(gaierr)); 301 close(sock); 302 return -1; 303 } 304 } 305 /* 306 * If we are running as root and want to connect to a privileged 307 * port, bind our own socket to a privileged port. 308 */ 309 if (privileged) { 310 PRIV_START; 311 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 312 PRIV_END; 313 if (r < 0) { 314 error("bindresvport_sa: af=%d %s", ai->ai_family, 315 strerror(errno)); 316 goto fail; 317 } 318 } else { 319 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 320 error("bind: %s: %s", options.bind_address, 321 strerror(errno)); 322 fail: 323 close(sock); 324 freeaddrinfo(res); 325 return -1; 326 } 327 } 328 if (res != NULL) 329 freeaddrinfo(res); 330 return sock; 331 } 332 333 static int 334 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 335 socklen_t addrlen, int *timeoutp) 336 { 337 fd_set *fdset; 338 struct timeval tv, t_start; 339 socklen_t optlen; 340 int optval, rc, result = -1; 341 342 gettimeofday(&t_start, NULL); 343 344 if (*timeoutp <= 0) { 345 result = connect(sockfd, serv_addr, addrlen); 346 goto done; 347 } 348 349 set_nonblock(sockfd); 350 rc = connect(sockfd, serv_addr, addrlen); 351 if (rc == 0) { 352 unset_nonblock(sockfd); 353 result = 0; 354 goto done; 355 } 356 if (errno != EINPROGRESS) { 357 result = -1; 358 goto done; 359 } 360 361 fdset = xcalloc(howmany(sockfd + 1, NFDBITS), 362 sizeof(fd_mask)); 363 FD_SET(sockfd, fdset); 364 ms_to_timeval(&tv, *timeoutp); 365 366 for (;;) { 367 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 368 if (rc != -1 || errno != EINTR) 369 break; 370 } 371 372 switch (rc) { 373 case 0: 374 /* Timed out */ 375 errno = ETIMEDOUT; 376 break; 377 case -1: 378 /* Select error */ 379 debug("select: %s", strerror(errno)); 380 break; 381 case 1: 382 /* Completed or failed */ 383 optval = 0; 384 optlen = sizeof(optval); 385 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 386 &optlen) == -1) { 387 debug("getsockopt: %s", strerror(errno)); 388 break; 389 } 390 if (optval != 0) { 391 errno = optval; 392 break; 393 } 394 result = 0; 395 unset_nonblock(sockfd); 396 break; 397 default: 398 /* Should not occur */ 399 fatal("Bogus return (%d) from select()", rc); 400 } 401 402 free(fdset); 403 404 done: 405 if (result == 0 && *timeoutp > 0) { 406 ms_subtract_diff(&t_start, timeoutp); 407 if (*timeoutp <= 0) { 408 errno = ETIMEDOUT; 409 result = -1; 410 } 411 } 412 413 return (result); 414 } 415 416 /* 417 * Opens a TCP/IP connection to the remote server on the given host. 418 * The address of the remote host will be returned in hostaddr. 419 * If port is 0, the default port will be used. If needpriv is true, 420 * a privileged port will be allocated to make the connection. 421 * This requires super-user privileges if needpriv is true. 422 * Connection_attempts specifies the maximum number of tries (one per 423 * second). If proxy_command is non-NULL, it specifies the command (with %h 424 * and %p substituted for host and port, respectively) to use to contact 425 * the daemon. 426 */ 427 static int 428 ssh_connect_direct(const char *host, struct addrinfo *aitop, 429 struct sockaddr_storage *hostaddr, u_short port, int family, 430 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 431 { 432 int on = 1; 433 int sock = -1, attempt; 434 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 435 struct addrinfo *ai; 436 437 debug2("%s: needpriv %d", __func__, needpriv); 438 memset(ntop, 0, sizeof(ntop)); 439 memset(strport, 0, sizeof(strport)); 440 441 for (attempt = 0; attempt < connection_attempts; attempt++) { 442 if (attempt > 0) { 443 /* Sleep a moment before retrying. */ 444 sleep(1); 445 debug("Trying again..."); 446 } 447 /* 448 * Loop through addresses for this host, and try each one in 449 * sequence until the connection succeeds. 450 */ 451 for (ai = aitop; ai; ai = ai->ai_next) { 452 if (ai->ai_family != AF_INET && 453 ai->ai_family != AF_INET6) 454 continue; 455 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 456 ntop, sizeof(ntop), strport, sizeof(strport), 457 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 458 error("%s: getnameinfo failed", __func__); 459 continue; 460 } 461 debug("Connecting to %.200s [%.100s] port %s.", 462 host, ntop, strport); 463 464 /* Create a socket for connecting. */ 465 sock = ssh_create_socket(needpriv, ai); 466 if (sock < 0) 467 /* Any error is already output */ 468 continue; 469 470 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 471 timeout_ms) >= 0) { 472 /* Successful connection. */ 473 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 474 break; 475 } else { 476 debug("connect to address %s port %s: %s", 477 ntop, strport, strerror(errno)); 478 close(sock); 479 sock = -1; 480 } 481 } 482 if (sock != -1) 483 break; /* Successful connection. */ 484 } 485 486 /* Return failure if we didn't get a successful connection. */ 487 if (sock == -1) { 488 error("ssh: connect to host %s port %s: %s", 489 host, strport, strerror(errno)); 490 return (-1); 491 } 492 493 debug("Connection established."); 494 495 /* Set SO_KEEPALIVE if requested. */ 496 if (want_keepalive && 497 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 498 sizeof(on)) < 0) 499 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 500 501 /* Set the connection. */ 502 packet_set_connection(sock, sock); 503 504 return 0; 505 } 506 507 int 508 ssh_connect(const char *host, struct addrinfo *addrs, 509 struct sockaddr_storage *hostaddr, u_short port, int family, 510 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 511 { 512 if (options.proxy_command == NULL) { 513 return ssh_connect_direct(host, addrs, hostaddr, port, family, 514 connection_attempts, timeout_ms, want_keepalive, needpriv); 515 } else if (strcmp(options.proxy_command, "-") == 0) { 516 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 517 return 0; /* Always succeeds */ 518 } else if (options.proxy_use_fdpass) { 519 return ssh_proxy_fdpass_connect(host, port, 520 options.proxy_command); 521 } 522 return ssh_proxy_connect(host, port, options.proxy_command); 523 } 524 525 static void 526 send_client_banner(int connection_out, int minor1) 527 { 528 /* Send our own protocol version identification. */ 529 if (compat20) { 530 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n", 531 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION); 532 } else { 533 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n", 534 PROTOCOL_MAJOR_1, minor1, SSH_VERSION); 535 } 536 if (atomicio(vwrite, connection_out, client_version_string, 537 strlen(client_version_string)) != strlen(client_version_string)) 538 fatal("write: %.100s", strerror(errno)); 539 chop(client_version_string); 540 debug("Local version string %.100s", client_version_string); 541 } 542 543 /* 544 * Waits for the server identification string, and sends our own 545 * identification string. 546 */ 547 void 548 ssh_exchange_identification(int timeout_ms) 549 { 550 char buf[256], remote_version[256]; /* must be same size! */ 551 int remote_major, remote_minor, mismatch; 552 int connection_in = packet_get_connection_in(); 553 int connection_out = packet_get_connection_out(); 554 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 555 u_int i, n; 556 size_t len; 557 int fdsetsz, remaining, rc; 558 struct timeval t_start, t_remaining; 559 fd_set *fdset; 560 561 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 562 fdset = xcalloc(1, fdsetsz); 563 564 /* 565 * If we are SSH2-only then we can send the banner immediately and 566 * save a round-trip. 567 */ 568 if (options.protocol == SSH_PROTO_2) { 569 enable_compat20(); 570 send_client_banner(connection_out, 0); 571 client_banner_sent = 1; 572 } 573 574 /* Read other side's version identification. */ 575 remaining = timeout_ms; 576 for (n = 0;;) { 577 for (i = 0; i < sizeof(buf) - 1; i++) { 578 if (timeout_ms > 0) { 579 gettimeofday(&t_start, NULL); 580 ms_to_timeval(&t_remaining, remaining); 581 FD_SET(connection_in, fdset); 582 rc = select(connection_in + 1, fdset, NULL, 583 fdset, &t_remaining); 584 ms_subtract_diff(&t_start, &remaining); 585 if (rc == 0 || remaining <= 0) 586 fatal("Connection timed out during " 587 "banner exchange"); 588 if (rc == -1) { 589 if (errno == EINTR) 590 continue; 591 fatal("ssh_exchange_identification: " 592 "select: %s", strerror(errno)); 593 } 594 } 595 596 len = atomicio(read, connection_in, &buf[i], 1); 597 598 if (len != 1 && errno == EPIPE) 599 fatal("ssh_exchange_identification: " 600 "Connection closed by remote host"); 601 else if (len != 1) 602 fatal("ssh_exchange_identification: " 603 "read: %.100s", strerror(errno)); 604 if (buf[i] == '\r') { 605 buf[i] = '\n'; 606 buf[i + 1] = 0; 607 continue; /**XXX wait for \n */ 608 } 609 if (buf[i] == '\n') { 610 buf[i + 1] = 0; 611 break; 612 } 613 if (++n > 65536) 614 fatal("ssh_exchange_identification: " 615 "No banner received"); 616 } 617 buf[sizeof(buf) - 1] = 0; 618 if (strncmp(buf, "SSH-", 4) == 0) 619 break; 620 debug("ssh_exchange_identification: %s", buf); 621 } 622 server_version_string = xstrdup(buf); 623 free(fdset); 624 625 /* 626 * Check that the versions match. In future this might accept 627 * several versions and set appropriate flags to handle them. 628 * 629 * NOTE: unbounded string to remote_version, but limited size of 630 * buf prevents overflow. 631 */ 632 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 633 &remote_major, &remote_minor, remote_version) != 3) 634 fatal("Bad remote protocol version identification: '%.100s'", buf); 635 debug("Remote protocol version %d.%d, remote software version %.100s", 636 remote_major, remote_minor, remote_version); 637 638 active_state->compat = compat_datafellows(remote_version); 639 mismatch = 0; 640 641 switch (remote_major) { 642 case 1: 643 if (remote_minor == 99 && 644 (options.protocol & SSH_PROTO_2) && 645 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 646 enable_compat20(); 647 break; 648 } 649 if (!(options.protocol & SSH_PROTO_1)) { 650 mismatch = 1; 651 break; 652 } 653 if (remote_minor < 3) { 654 fatal("Remote machine has too old SSH software version."); 655 } else if (remote_minor == 3 || remote_minor == 4) { 656 /* We speak 1.3, too. */ 657 enable_compat13(); 658 minor1 = 3; 659 if (options.forward_agent) { 660 logit("Agent forwarding disabled for protocol 1.3"); 661 options.forward_agent = 0; 662 } 663 } 664 break; 665 case 2: 666 if (options.protocol & SSH_PROTO_2) { 667 enable_compat20(); 668 break; 669 } 670 /* FALLTHROUGH */ 671 default: 672 mismatch = 1; 673 break; 674 } 675 if (mismatch) 676 fatal("Protocol major versions differ: %d vs. %d", 677 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 678 remote_major); 679 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 680 fatal("Server version \"%.100s\" uses unsafe key agreement; " 681 "refusing connection", remote_version); 682 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 683 logit("Server version \"%.100s\" uses unsafe RSA signature " 684 "scheme; disabling use of RSA keys", remote_version); 685 if (!client_banner_sent) 686 send_client_banner(connection_out, minor1); 687 chop(server_version_string); 688 } 689 690 /* defaults to 'no' */ 691 static int 692 confirm(const char *prompt) 693 { 694 const char *msg, *again = "Please type 'yes' or 'no': "; 695 char *p; 696 int ret = -1; 697 698 if (options.batch_mode) 699 return 0; 700 for (msg = prompt;;msg = again) { 701 p = read_passphrase(msg, RP_ECHO); 702 if (p == NULL || 703 (p[0] == '\0') || (p[0] == '\n') || 704 strncasecmp(p, "no", 2) == 0) 705 ret = 0; 706 if (p && strncasecmp(p, "yes", 3) == 0) 707 ret = 1; 708 free(p); 709 if (ret != -1) 710 return ret; 711 } 712 } 713 714 static int 715 check_host_cert(const char *host, const Key *host_key) 716 { 717 const char *reason; 718 719 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 720 error("%s", reason); 721 return 0; 722 } 723 if (buffer_len(host_key->cert->critical) != 0) { 724 error("Certificate for %s contains unsupported " 725 "critical options(s)", host); 726 return 0; 727 } 728 return 1; 729 } 730 731 static int 732 sockaddr_is_local(struct sockaddr *hostaddr) 733 { 734 switch (hostaddr->sa_family) { 735 case AF_INET: 736 return (ntohl(((struct sockaddr_in *)hostaddr)-> 737 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 738 case AF_INET6: 739 return IN6_IS_ADDR_LOOPBACK( 740 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 741 default: 742 return 0; 743 } 744 } 745 746 /* 747 * Prepare the hostname and ip address strings that are used to lookup 748 * host keys in known_hosts files. These may have a port number appended. 749 */ 750 void 751 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 752 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 753 { 754 char ntop[NI_MAXHOST]; 755 socklen_t addrlen; 756 757 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 758 case -1: 759 addrlen = 0; 760 break; 761 case AF_INET: 762 addrlen = sizeof(struct sockaddr_in); 763 break; 764 case AF_INET6: 765 addrlen = sizeof(struct sockaddr_in6); 766 break; 767 default: 768 addrlen = sizeof(struct sockaddr); 769 break; 770 } 771 772 /* 773 * We don't have the remote ip-address for connections 774 * using a proxy command 775 */ 776 if (hostfile_ipaddr != NULL) { 777 if (options.proxy_command == NULL) { 778 if (getnameinfo(hostaddr, addrlen, 779 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 780 fatal("%s: getnameinfo failed", __func__); 781 *hostfile_ipaddr = put_host_port(ntop, port); 782 } else { 783 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 784 "command>"); 785 } 786 } 787 788 /* 789 * Allow the user to record the key under a different name or 790 * differentiate a non-standard port. This is useful for ssh 791 * tunneling over forwarded connections or if you run multiple 792 * sshd's on different ports on the same machine. 793 */ 794 if (hostfile_hostname != NULL) { 795 if (options.host_key_alias != NULL) { 796 *hostfile_hostname = xstrdup(options.host_key_alias); 797 debug("using hostkeyalias: %s", *hostfile_hostname); 798 } else { 799 *hostfile_hostname = put_host_port(hostname, port); 800 } 801 } 802 } 803 804 /* 805 * check whether the supplied host key is valid, return -1 if the key 806 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 807 */ 808 #define RDRW 0 809 #define RDONLY 1 810 #define ROQUIET 2 811 static int 812 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 813 Key *host_key, int readonly, 814 char **user_hostfiles, u_int num_user_hostfiles, 815 char **system_hostfiles, u_int num_system_hostfiles) 816 { 817 HostStatus host_status; 818 HostStatus ip_status; 819 Key *raw_key = NULL; 820 char *ip = NULL, *host = NULL; 821 char hostline[1000], *hostp, *fp, *ra; 822 char msg[1024]; 823 const char *type; 824 const struct hostkey_entry *host_found, *ip_found; 825 int len, cancelled_forwarding = 0; 826 int local = sockaddr_is_local(hostaddr); 827 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 828 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 829 struct hostkeys *host_hostkeys, *ip_hostkeys; 830 u_int i; 831 832 /* 833 * Force accepting of the host key for loopback/localhost. The 834 * problem is that if the home directory is NFS-mounted to multiple 835 * machines, localhost will refer to a different machine in each of 836 * them, and the user will get bogus HOST_CHANGED warnings. This 837 * essentially disables host authentication for localhost; however, 838 * this is probably not a real problem. 839 */ 840 if (options.no_host_authentication_for_localhost == 1 && local && 841 options.host_key_alias == NULL) { 842 debug("Forcing accepting of host key for " 843 "loopback/localhost."); 844 return 0; 845 } 846 847 /* 848 * Prepare the hostname and address strings used for hostkey lookup. 849 * In some cases, these will have a port number appended. 850 */ 851 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 852 853 /* 854 * Turn off check_host_ip if the connection is to localhost, via proxy 855 * command or if we don't have a hostname to compare with 856 */ 857 if (options.check_host_ip && (local || 858 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 859 options.check_host_ip = 0; 860 861 host_hostkeys = init_hostkeys(); 862 for (i = 0; i < num_user_hostfiles; i++) 863 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 864 for (i = 0; i < num_system_hostfiles; i++) 865 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 866 867 ip_hostkeys = NULL; 868 if (!want_cert && options.check_host_ip) { 869 ip_hostkeys = init_hostkeys(); 870 for (i = 0; i < num_user_hostfiles; i++) 871 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 872 for (i = 0; i < num_system_hostfiles; i++) 873 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 874 } 875 876 retry: 877 /* Reload these as they may have changed on cert->key downgrade */ 878 want_cert = key_is_cert(host_key); 879 type = key_type(host_key); 880 881 /* 882 * Check if the host key is present in the user's list of known 883 * hosts or in the systemwide list. 884 */ 885 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 886 &host_found); 887 888 /* 889 * Also perform check for the ip address, skip the check if we are 890 * localhost, looking for a certificate, or the hostname was an ip 891 * address to begin with. 892 */ 893 if (!want_cert && ip_hostkeys != NULL) { 894 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 895 &ip_found); 896 if (host_status == HOST_CHANGED && 897 (ip_status != HOST_CHANGED || 898 (ip_found != NULL && 899 !key_equal(ip_found->key, host_found->key)))) 900 host_ip_differ = 1; 901 } else 902 ip_status = host_status; 903 904 switch (host_status) { 905 case HOST_OK: 906 /* The host is known and the key matches. */ 907 debug("Host '%.200s' is known and matches the %s host %s.", 908 host, type, want_cert ? "certificate" : "key"); 909 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 910 host_found->file, host_found->line); 911 if (want_cert && !check_host_cert(hostname, host_key)) 912 goto fail; 913 if (options.check_host_ip && ip_status == HOST_NEW) { 914 if (readonly || want_cert) 915 logit("%s host key for IP address " 916 "'%.128s' not in list of known hosts.", 917 type, ip); 918 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 919 host_key, options.hash_known_hosts)) 920 logit("Failed to add the %s host key for IP " 921 "address '%.128s' to the list of known " 922 "hosts (%.500s).", type, ip, 923 user_hostfiles[0]); 924 else 925 logit("Warning: Permanently added the %s host " 926 "key for IP address '%.128s' to the list " 927 "of known hosts.", type, ip); 928 } else if (options.visual_host_key) { 929 fp = sshkey_fingerprint(host_key, 930 options.fingerprint_hash, SSH_FP_DEFAULT); 931 ra = sshkey_fingerprint(host_key, 932 options.fingerprint_hash, SSH_FP_RANDOMART); 933 if (fp == NULL || ra == NULL) 934 fatal("%s: sshkey_fingerprint fail", __func__); 935 logit("Host key fingerprint is %s\n%s", fp, ra); 936 free(ra); 937 free(fp); 938 } 939 hostkey_trusted = 1; 940 break; 941 case HOST_NEW: 942 if (options.host_key_alias == NULL && port != 0 && 943 port != SSH_DEFAULT_PORT) { 944 debug("checking without port identifier"); 945 if (check_host_key(hostname, hostaddr, 0, host_key, 946 ROQUIET, user_hostfiles, num_user_hostfiles, 947 system_hostfiles, num_system_hostfiles) == 0) { 948 debug("found matching key w/out port"); 949 break; 950 } 951 } 952 if (readonly || want_cert) 953 goto fail; 954 /* The host is new. */ 955 if (options.strict_host_key_checking == 1) { 956 /* 957 * User has requested strict host key checking. We 958 * will not add the host key automatically. The only 959 * alternative left is to abort. 960 */ 961 error("No %s host key is known for %.200s and you " 962 "have requested strict checking.", type, host); 963 goto fail; 964 } else if (options.strict_host_key_checking == 2) { 965 char msg1[1024], msg2[1024]; 966 967 if (show_other_keys(host_hostkeys, host_key)) 968 snprintf(msg1, sizeof(msg1), 969 "\nbut keys of different type are already" 970 " known for this host."); 971 else 972 snprintf(msg1, sizeof(msg1), "."); 973 /* The default */ 974 fp = sshkey_fingerprint(host_key, 975 options.fingerprint_hash, SSH_FP_DEFAULT); 976 ra = sshkey_fingerprint(host_key, 977 options.fingerprint_hash, SSH_FP_RANDOMART); 978 if (fp == NULL || ra == NULL) 979 fatal("%s: sshkey_fingerprint fail", __func__); 980 msg2[0] = '\0'; 981 if (options.verify_host_key_dns) { 982 if (matching_host_key_dns) 983 snprintf(msg2, sizeof(msg2), 984 "Matching host key fingerprint" 985 " found in DNS.\n"); 986 else 987 snprintf(msg2, sizeof(msg2), 988 "No matching host key fingerprint" 989 " found in DNS.\n"); 990 } 991 snprintf(msg, sizeof(msg), 992 "The authenticity of host '%.200s (%s)' can't be " 993 "established%s\n" 994 "%s key fingerprint is %s.%s%s\n%s" 995 "Are you sure you want to continue connecting " 996 "(yes/no)? ", 997 host, ip, msg1, type, fp, 998 options.visual_host_key ? "\n" : "", 999 options.visual_host_key ? ra : "", 1000 msg2); 1001 free(ra); 1002 free(fp); 1003 if (!confirm(msg)) 1004 goto fail; 1005 hostkey_trusted = 1; /* user explicitly confirmed */ 1006 } 1007 /* 1008 * If not in strict mode, add the key automatically to the 1009 * local known_hosts file. 1010 */ 1011 if (options.check_host_ip && ip_status == HOST_NEW) { 1012 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 1013 hostp = hostline; 1014 if (options.hash_known_hosts) { 1015 /* Add hash of host and IP separately */ 1016 r = add_host_to_hostfile(user_hostfiles[0], 1017 host, host_key, options.hash_known_hosts) && 1018 add_host_to_hostfile(user_hostfiles[0], ip, 1019 host_key, options.hash_known_hosts); 1020 } else { 1021 /* Add unhashed "host,ip" */ 1022 r = add_host_to_hostfile(user_hostfiles[0], 1023 hostline, host_key, 1024 options.hash_known_hosts); 1025 } 1026 } else { 1027 r = add_host_to_hostfile(user_hostfiles[0], host, 1028 host_key, options.hash_known_hosts); 1029 hostp = host; 1030 } 1031 1032 if (!r) 1033 logit("Failed to add the host to the list of known " 1034 "hosts (%.500s).", user_hostfiles[0]); 1035 else 1036 logit("Warning: Permanently added '%.200s' (%s) to the " 1037 "list of known hosts.", hostp, type); 1038 break; 1039 case HOST_REVOKED: 1040 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1041 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1042 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1043 error("The %s host key for %s is marked as revoked.", type, host); 1044 error("This could mean that a stolen key is being used to"); 1045 error("impersonate this host."); 1046 1047 /* 1048 * If strict host key checking is in use, the user will have 1049 * to edit the key manually and we can only abort. 1050 */ 1051 if (options.strict_host_key_checking) { 1052 error("%s host key for %.200s was revoked and you have " 1053 "requested strict checking.", type, host); 1054 goto fail; 1055 } 1056 goto continue_unsafe; 1057 1058 case HOST_CHANGED: 1059 if (want_cert) { 1060 /* 1061 * This is only a debug() since it is valid to have 1062 * CAs with wildcard DNS matches that don't match 1063 * all hosts that one might visit. 1064 */ 1065 debug("Host certificate authority does not " 1066 "match %s in %s:%lu", CA_MARKER, 1067 host_found->file, host_found->line); 1068 goto fail; 1069 } 1070 if (readonly == ROQUIET) 1071 goto fail; 1072 if (options.check_host_ip && host_ip_differ) { 1073 char *key_msg; 1074 if (ip_status == HOST_NEW) 1075 key_msg = "is unknown"; 1076 else if (ip_status == HOST_OK) 1077 key_msg = "is unchanged"; 1078 else 1079 key_msg = "has a different value"; 1080 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1081 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1082 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1083 error("The %s host key for %s has changed,", type, host); 1084 error("and the key for the corresponding IP address %s", ip); 1085 error("%s. This could either mean that", key_msg); 1086 error("DNS SPOOFING is happening or the IP address for the host"); 1087 error("and its host key have changed at the same time."); 1088 if (ip_status != HOST_NEW) 1089 error("Offending key for IP in %s:%lu", 1090 ip_found->file, ip_found->line); 1091 } 1092 /* The host key has changed. */ 1093 warn_changed_key(host_key); 1094 error("Add correct host key in %.100s to get rid of this message.", 1095 user_hostfiles[0]); 1096 error("Offending %s key in %s:%lu", key_type(host_found->key), 1097 host_found->file, host_found->line); 1098 1099 /* 1100 * If strict host key checking is in use, the user will have 1101 * to edit the key manually and we can only abort. 1102 */ 1103 if (options.strict_host_key_checking) { 1104 error("%s host key for %.200s has changed and you have " 1105 "requested strict checking.", type, host); 1106 goto fail; 1107 } 1108 1109 continue_unsafe: 1110 /* 1111 * If strict host key checking has not been requested, allow 1112 * the connection but without MITM-able authentication or 1113 * forwarding. 1114 */ 1115 if (options.password_authentication) { 1116 error("Password authentication is disabled to avoid " 1117 "man-in-the-middle attacks."); 1118 options.password_authentication = 0; 1119 cancelled_forwarding = 1; 1120 } 1121 if (options.kbd_interactive_authentication) { 1122 error("Keyboard-interactive authentication is disabled" 1123 " to avoid man-in-the-middle attacks."); 1124 options.kbd_interactive_authentication = 0; 1125 options.challenge_response_authentication = 0; 1126 cancelled_forwarding = 1; 1127 } 1128 if (options.challenge_response_authentication) { 1129 error("Challenge/response authentication is disabled" 1130 " to avoid man-in-the-middle attacks."); 1131 options.challenge_response_authentication = 0; 1132 cancelled_forwarding = 1; 1133 } 1134 if (options.forward_agent) { 1135 error("Agent forwarding is disabled to avoid " 1136 "man-in-the-middle attacks."); 1137 options.forward_agent = 0; 1138 cancelled_forwarding = 1; 1139 } 1140 if (options.forward_x11) { 1141 error("X11 forwarding is disabled to avoid " 1142 "man-in-the-middle attacks."); 1143 options.forward_x11 = 0; 1144 cancelled_forwarding = 1; 1145 } 1146 if (options.num_local_forwards > 0 || 1147 options.num_remote_forwards > 0) { 1148 error("Port forwarding is disabled to avoid " 1149 "man-in-the-middle attacks."); 1150 options.num_local_forwards = 1151 options.num_remote_forwards = 0; 1152 cancelled_forwarding = 1; 1153 } 1154 if (options.tun_open != SSH_TUNMODE_NO) { 1155 error("Tunnel forwarding is disabled to avoid " 1156 "man-in-the-middle attacks."); 1157 options.tun_open = SSH_TUNMODE_NO; 1158 cancelled_forwarding = 1; 1159 } 1160 if (options.exit_on_forward_failure && cancelled_forwarding) 1161 fatal("Error: forwarding disabled due to host key " 1162 "check failure"); 1163 1164 /* 1165 * XXX Should permit the user to change to use the new id. 1166 * This could be done by converting the host key to an 1167 * identifying sentence, tell that the host identifies itself 1168 * by that sentence, and ask the user if he/she wishes to 1169 * accept the authentication. 1170 */ 1171 break; 1172 case HOST_FOUND: 1173 fatal("internal error"); 1174 break; 1175 } 1176 1177 if (options.check_host_ip && host_status != HOST_CHANGED && 1178 ip_status == HOST_CHANGED) { 1179 snprintf(msg, sizeof(msg), 1180 "Warning: the %s host key for '%.200s' " 1181 "differs from the key for the IP address '%.128s'" 1182 "\nOffending key for IP in %s:%lu", 1183 type, host, ip, ip_found->file, ip_found->line); 1184 if (host_status == HOST_OK) { 1185 len = strlen(msg); 1186 snprintf(msg + len, sizeof(msg) - len, 1187 "\nMatching host key in %s:%lu", 1188 host_found->file, host_found->line); 1189 } 1190 if (options.strict_host_key_checking == 1) { 1191 logit("%s", msg); 1192 error("Exiting, you have requested strict checking."); 1193 goto fail; 1194 } else if (options.strict_host_key_checking == 2) { 1195 strlcat(msg, "\nAre you sure you want " 1196 "to continue connecting (yes/no)? ", sizeof(msg)); 1197 if (!confirm(msg)) 1198 goto fail; 1199 } else { 1200 logit("%s", msg); 1201 } 1202 } 1203 1204 if (!hostkey_trusted && options.update_hostkeys) { 1205 debug("%s: hostkey not known or explicitly trusted: " 1206 "disabling UpdateHostkeys", __func__); 1207 options.update_hostkeys = 0; 1208 } 1209 1210 free(ip); 1211 free(host); 1212 if (host_hostkeys != NULL) 1213 free_hostkeys(host_hostkeys); 1214 if (ip_hostkeys != NULL) 1215 free_hostkeys(ip_hostkeys); 1216 return 0; 1217 1218 fail: 1219 if (want_cert && host_status != HOST_REVOKED) { 1220 /* 1221 * No matching certificate. Downgrade cert to raw key and 1222 * search normally. 1223 */ 1224 debug("No matching CA found. Retry with plain key"); 1225 raw_key = key_from_private(host_key); 1226 if (key_drop_cert(raw_key) != 0) 1227 fatal("Couldn't drop certificate"); 1228 host_key = raw_key; 1229 goto retry; 1230 } 1231 if (raw_key != NULL) 1232 key_free(raw_key); 1233 free(ip); 1234 free(host); 1235 if (host_hostkeys != NULL) 1236 free_hostkeys(host_hostkeys); 1237 if (ip_hostkeys != NULL) 1238 free_hostkeys(ip_hostkeys); 1239 return -1; 1240 } 1241 1242 /* returns 0 if key verifies or -1 if key does NOT verify */ 1243 int 1244 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1245 { 1246 u_int i; 1247 int r = -1, flags = 0; 1248 char valid[64], *fp = NULL, *cafp = NULL; 1249 struct sshkey *plain = NULL; 1250 1251 if ((fp = sshkey_fingerprint(host_key, 1252 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1253 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1254 r = -1; 1255 goto out; 1256 } 1257 1258 if (sshkey_is_cert(host_key)) { 1259 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1260 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1261 error("%s: fingerprint CA key: %s", 1262 __func__, ssh_err(r)); 1263 r = -1; 1264 goto out; 1265 } 1266 sshkey_format_cert_validity(host_key->cert, 1267 valid, sizeof(valid)); 1268 debug("Server host certificate: %s %s, serial %llu " 1269 "ID \"%s\" CA %s %s valid %s", 1270 sshkey_ssh_name(host_key), fp, 1271 (unsigned long long)host_key->cert->serial, 1272 host_key->cert->key_id, 1273 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1274 valid); 1275 for (i = 0; i < host_key->cert->nprincipals; i++) { 1276 debug2("Server host certificate hostname: %s", 1277 host_key->cert->principals[i]); 1278 } 1279 } else { 1280 debug("Server host key: %s %s", compat20 ? 1281 sshkey_ssh_name(host_key) : sshkey_type(host_key), fp); 1282 } 1283 1284 if (sshkey_equal(previous_host_key, host_key)) { 1285 debug2("%s: server host key %s %s matches cached key", 1286 __func__, sshkey_type(host_key), fp); 1287 r = 0; 1288 goto out; 1289 } 1290 1291 /* Check in RevokedHostKeys file if specified */ 1292 if (options.revoked_host_keys != NULL) { 1293 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1294 switch (r) { 1295 case 0: 1296 break; /* not revoked */ 1297 case SSH_ERR_KEY_REVOKED: 1298 error("Host key %s %s revoked by file %s", 1299 sshkey_type(host_key), fp, 1300 options.revoked_host_keys); 1301 r = -1; 1302 goto out; 1303 default: 1304 error("Error checking host key %s %s in " 1305 "revoked keys file %s: %s", sshkey_type(host_key), 1306 fp, options.revoked_host_keys, ssh_err(r)); 1307 r = -1; 1308 goto out; 1309 } 1310 } 1311 1312 if (options.verify_host_key_dns) { 1313 /* 1314 * XXX certs are not yet supported for DNS, so downgrade 1315 * them and try the plain key. 1316 */ 1317 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1318 goto out; 1319 if (sshkey_is_cert(plain)) 1320 sshkey_drop_cert(plain); 1321 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1322 if (flags & DNS_VERIFY_FOUND) { 1323 if (options.verify_host_key_dns == 1 && 1324 flags & DNS_VERIFY_MATCH && 1325 flags & DNS_VERIFY_SECURE) { 1326 r = 0; 1327 goto out; 1328 } 1329 if (flags & DNS_VERIFY_MATCH) { 1330 matching_host_key_dns = 1; 1331 } else { 1332 warn_changed_key(plain); 1333 error("Update the SSHFP RR in DNS " 1334 "with the new host key to get rid " 1335 "of this message."); 1336 } 1337 } 1338 } 1339 } 1340 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1341 options.user_hostfiles, options.num_user_hostfiles, 1342 options.system_hostfiles, options.num_system_hostfiles); 1343 1344 out: 1345 sshkey_free(plain); 1346 free(fp); 1347 free(cafp); 1348 if (r == 0 && host_key != NULL) { 1349 key_free(previous_host_key); 1350 previous_host_key = key_from_private(host_key); 1351 } 1352 1353 return r; 1354 } 1355 1356 /* 1357 * Starts a dialog with the server, and authenticates the current user on the 1358 * server. This does not need any extra privileges. The basic connection 1359 * to the server must already have been established before this is called. 1360 * If login fails, this function prints an error and never returns. 1361 * This function does not require super-user privileges. 1362 */ 1363 void 1364 ssh_login(Sensitive *sensitive, const char *orighost, 1365 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1366 { 1367 char *host; 1368 char *server_user, *local_user; 1369 1370 local_user = xstrdup(pw->pw_name); 1371 server_user = options.user ? options.user : local_user; 1372 1373 /* Convert the user-supplied hostname into all lowercase. */ 1374 host = xstrdup(orighost); 1375 lowercase(host); 1376 1377 /* Exchange protocol version identification strings with the server. */ 1378 ssh_exchange_identification(timeout_ms); 1379 1380 /* Put the connection into non-blocking mode. */ 1381 packet_set_nonblocking(); 1382 1383 /* key exchange */ 1384 /* authenticate user */ 1385 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1386 if (compat20) { 1387 ssh_kex2(host, hostaddr, port); 1388 ssh_userauth2(local_user, server_user, host, sensitive); 1389 } else { 1390 #ifdef WITH_SSH1 1391 ssh_kex(host, hostaddr); 1392 ssh_userauth1(local_user, server_user, host, sensitive); 1393 #else 1394 fatal("ssh1 is not supported"); 1395 #endif 1396 } 1397 free(local_user); 1398 } 1399 1400 void 1401 ssh_put_password(char *password) 1402 { 1403 int size; 1404 char *padded; 1405 1406 if (datafellows & SSH_BUG_PASSWORDPAD) { 1407 packet_put_cstring(password); 1408 return; 1409 } 1410 size = roundup(strlen(password) + 1, 32); 1411 padded = xcalloc(1, size); 1412 strlcpy(padded, password, size); 1413 packet_put_string(padded, size); 1414 explicit_bzero(padded, size); 1415 free(padded); 1416 } 1417 1418 /* print all known host keys for a given host, but skip keys of given type */ 1419 static int 1420 show_other_keys(struct hostkeys *hostkeys, Key *key) 1421 { 1422 int type[] = { 1423 KEY_RSA1, 1424 KEY_RSA, 1425 KEY_DSA, 1426 KEY_ECDSA, 1427 KEY_ED25519, 1428 -1 1429 }; 1430 int i, ret = 0; 1431 char *fp, *ra; 1432 const struct hostkey_entry *found; 1433 1434 for (i = 0; type[i] != -1; i++) { 1435 if (type[i] == key->type) 1436 continue; 1437 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1438 continue; 1439 fp = sshkey_fingerprint(found->key, 1440 options.fingerprint_hash, SSH_FP_DEFAULT); 1441 ra = sshkey_fingerprint(found->key, 1442 options.fingerprint_hash, SSH_FP_RANDOMART); 1443 if (fp == NULL || ra == NULL) 1444 fatal("%s: sshkey_fingerprint fail", __func__); 1445 logit("WARNING: %s key found for host %s\n" 1446 "in %s:%lu\n" 1447 "%s key fingerprint %s.", 1448 key_type(found->key), 1449 found->host, found->file, found->line, 1450 key_type(found->key), fp); 1451 if (options.visual_host_key) 1452 logit("%s", ra); 1453 free(ra); 1454 free(fp); 1455 ret = 1; 1456 } 1457 return ret; 1458 } 1459 1460 static void 1461 warn_changed_key(Key *host_key) 1462 { 1463 char *fp; 1464 1465 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1466 SSH_FP_DEFAULT); 1467 if (fp == NULL) 1468 fatal("%s: sshkey_fingerprint fail", __func__); 1469 1470 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1471 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1472 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1473 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1474 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1475 error("It is also possible that a host key has just been changed."); 1476 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1477 key_type(host_key), fp); 1478 error("Please contact your system administrator."); 1479 1480 free(fp); 1481 } 1482 1483 /* 1484 * Execute a local command 1485 */ 1486 int 1487 ssh_local_cmd(const char *args) 1488 { 1489 char *shell; 1490 pid_t pid; 1491 int status; 1492 void (*osighand)(int); 1493 1494 if (!options.permit_local_command || 1495 args == NULL || !*args) 1496 return (1); 1497 1498 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1499 shell = _PATH_BSHELL; 1500 1501 osighand = signal(SIGCHLD, SIG_DFL); 1502 pid = fork(); 1503 if (pid == 0) { 1504 signal(SIGPIPE, SIG_DFL); 1505 debug3("Executing %s -c \"%s\"", shell, args); 1506 execl(shell, shell, "-c", args, (char *)NULL); 1507 error("Couldn't execute %s -c \"%s\": %s", 1508 shell, args, strerror(errno)); 1509 _exit(1); 1510 } else if (pid == -1) 1511 fatal("fork failed: %.100s", strerror(errno)); 1512 while (waitpid(pid, &status, 0) == -1) 1513 if (errno != EINTR) 1514 fatal("Couldn't wait for child: %s", strerror(errno)); 1515 signal(SIGCHLD, osighand); 1516 1517 if (!WIFEXITED(status)) 1518 return (1); 1519 1520 return (WEXITSTATUS(status)); 1521 } 1522 1523 void 1524 maybe_add_key_to_agent(char *authfile, Key *private, char *comment, 1525 char *passphrase) 1526 { 1527 int auth_sock = -1, r; 1528 1529 if (options.add_keys_to_agent == 0) 1530 return; 1531 1532 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1533 debug3("no authentication agent, not adding key"); 1534 return; 1535 } 1536 1537 if (options.add_keys_to_agent == 2 && 1538 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1539 debug3("user denied adding this key"); 1540 return; 1541 } 1542 1543 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0, 1544 (options.add_keys_to_agent == 3))) == 0) 1545 debug("identity added to agent: %s", authfile); 1546 else 1547 debug("could not add identity to agent: %s (%d)", authfile, r); 1548 } 1549