1 /* $OpenBSD: sshconnect.c,v 1.273 2017/03/10 03:22:40 dtucker Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) 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/types.h> 19 #include <sys/wait.h> 20 #include <sys/stat.h> 21 #include <sys/socket.h> 22 #ifdef HAVE_SYS_TIME_H 23 # include <sys/time.h> 24 #endif 25 26 #include <netinet/in.h> 27 #include <arpa/inet.h> 28 29 #include <ctype.h> 30 #include <errno.h> 31 #include <fcntl.h> 32 #include <netdb.h> 33 #ifdef HAVE_PATHS_H 34 #include <paths.h> 35 #endif 36 #include <pwd.h> 37 #include <signal.h> 38 #include <stdarg.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include <unistd.h> 43 44 #include "xmalloc.h" 45 #include "key.h" 46 #include "hostfile.h" 47 #include "ssh.h" 48 #include "rsa.h" 49 #include "buffer.h" 50 #include "packet.h" 51 #include "uidswap.h" 52 #include "compat.h" 53 #include "key.h" 54 #include "sshconnect.h" 55 #include "hostfile.h" 56 #include "log.h" 57 #include "misc.h" 58 #include "readconf.h" 59 #include "atomicio.h" 60 #include "dns.h" 61 #include "monitor_fdpass.h" 62 #include "ssh2.h" 63 #include "version.h" 64 #include "authfile.h" 65 #include "ssherr.h" 66 #include "authfd.h" 67 68 char *client_version_string = NULL; 69 char *server_version_string = NULL; 70 Key *previous_host_key = NULL; 71 72 static int matching_host_key_dns = 0; 73 74 static pid_t proxy_command_pid = 0; 75 76 /* import */ 77 extern Options options; 78 extern char *__progname; 79 extern uid_t original_real_uid; 80 extern uid_t original_effective_uid; 81 82 static int show_other_keys(struct hostkeys *, Key *); 83 static void warn_changed_key(Key *); 84 85 /* Expand a proxy command */ 86 static char * 87 expand_proxy_command(const char *proxy_command, const char *user, 88 const char *host, int port) 89 { 90 char *tmp, *ret, strport[NI_MAXSERV]; 91 92 snprintf(strport, sizeof strport, "%d", port); 93 xasprintf(&tmp, "exec %s", proxy_command); 94 ret = percent_expand(tmp, "h", host, "p", strport, 95 "r", options.user, (char *)NULL); 96 free(tmp); 97 return ret; 98 } 99 100 /* 101 * Connect to the given ssh server using a proxy command that passes a 102 * a connected fd back to us. 103 */ 104 static int 105 ssh_proxy_fdpass_connect(const char *host, u_short port, 106 const char *proxy_command) 107 { 108 char *command_string; 109 int sp[2], sock; 110 pid_t pid; 111 char *shell; 112 113 if ((shell = getenv("SHELL")) == NULL) 114 shell = _PATH_BSHELL; 115 116 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 117 fatal("Could not create socketpair to communicate with " 118 "proxy dialer: %.100s", strerror(errno)); 119 120 command_string = expand_proxy_command(proxy_command, options.user, 121 host, port); 122 debug("Executing proxy dialer command: %.500s", command_string); 123 124 /* Fork and execute the proxy command. */ 125 if ((pid = fork()) == 0) { 126 char *argv[10]; 127 128 /* Child. Permanently give up superuser privileges. */ 129 permanently_drop_suid(original_real_uid); 130 131 close(sp[1]); 132 /* Redirect stdin and stdout. */ 133 if (sp[0] != 0) { 134 if (dup2(sp[0], 0) < 0) 135 perror("dup2 stdin"); 136 } 137 if (sp[0] != 1) { 138 if (dup2(sp[0], 1) < 0) 139 perror("dup2 stdout"); 140 } 141 if (sp[0] >= 2) 142 close(sp[0]); 143 144 /* 145 * Stderr is left as it is so that error messages get 146 * printed on the user's terminal. 147 */ 148 argv[0] = shell; 149 argv[1] = "-c"; 150 argv[2] = command_string; 151 argv[3] = NULL; 152 153 /* 154 * Execute the proxy command. 155 * Note that we gave up any extra privileges above. 156 */ 157 execv(argv[0], argv); 158 perror(argv[0]); 159 exit(1); 160 } 161 /* Parent. */ 162 if (pid < 0) 163 fatal("fork failed: %.100s", strerror(errno)); 164 close(sp[0]); 165 free(command_string); 166 167 if ((sock = mm_receive_fd(sp[1])) == -1) 168 fatal("proxy dialer did not pass back a connection"); 169 close(sp[1]); 170 171 while (waitpid(pid, NULL, 0) == -1) 172 if (errno != EINTR) 173 fatal("Couldn't wait for child: %s", strerror(errno)); 174 175 /* Set the connection file descriptors. */ 176 packet_set_connection(sock, sock); 177 178 return 0; 179 } 180 181 /* 182 * Connect to the given ssh server using a proxy command. 183 */ 184 static int 185 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) 186 { 187 char *command_string; 188 int pin[2], pout[2]; 189 pid_t pid; 190 char *shell; 191 192 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 193 shell = _PATH_BSHELL; 194 195 /* Create pipes for communicating with the proxy. */ 196 if (pipe(pin) < 0 || pipe(pout) < 0) 197 fatal("Could not create pipes to communicate with the proxy: %.100s", 198 strerror(errno)); 199 200 command_string = expand_proxy_command(proxy_command, options.user, 201 host, port); 202 debug("Executing proxy command: %.500s", command_string); 203 204 /* Fork and execute the proxy command. */ 205 if ((pid = fork()) == 0) { 206 char *argv[10]; 207 208 /* Child. Permanently give up superuser privileges. */ 209 permanently_drop_suid(original_real_uid); 210 211 /* Redirect stdin and stdout. */ 212 close(pin[1]); 213 if (pin[0] != 0) { 214 if (dup2(pin[0], 0) < 0) 215 perror("dup2 stdin"); 216 close(pin[0]); 217 } 218 close(pout[0]); 219 if (dup2(pout[1], 1) < 0) 220 perror("dup2 stdout"); 221 /* Cannot be 1 because pin allocated two descriptors. */ 222 close(pout[1]); 223 224 /* Stderr is left as it is so that error messages get 225 printed on the user's terminal. */ 226 argv[0] = shell; 227 argv[1] = "-c"; 228 argv[2] = command_string; 229 argv[3] = NULL; 230 231 /* Execute the proxy command. Note that we gave up any 232 extra privileges above. */ 233 signal(SIGPIPE, SIG_DFL); 234 execv(argv[0], argv); 235 perror(argv[0]); 236 exit(1); 237 } 238 /* Parent. */ 239 if (pid < 0) 240 fatal("fork failed: %.100s", strerror(errno)); 241 else 242 proxy_command_pid = pid; /* save pid to clean up later */ 243 244 /* Close child side of the descriptors. */ 245 close(pin[0]); 246 close(pout[1]); 247 248 /* Free the command name. */ 249 free(command_string); 250 251 /* Set the connection file descriptors. */ 252 packet_set_connection(pout[0], pin[1]); 253 254 /* Indicate OK return */ 255 return 0; 256 } 257 258 void 259 ssh_kill_proxy_command(void) 260 { 261 /* 262 * Send SIGHUP to proxy command if used. We don't wait() in 263 * case it hangs and instead rely on init to reap the child 264 */ 265 if (proxy_command_pid > 1) 266 kill(proxy_command_pid, SIGHUP); 267 } 268 269 /* 270 * Creates a (possibly privileged) socket for use as the ssh connection. 271 */ 272 static int 273 ssh_create_socket(int privileged, struct addrinfo *ai) 274 { 275 int sock, r, gaierr; 276 struct addrinfo hints, *res = NULL; 277 278 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 279 if (sock < 0) { 280 error("socket: %s", strerror(errno)); 281 return -1; 282 } 283 fcntl(sock, F_SETFD, FD_CLOEXEC); 284 285 /* Bind the socket to an alternative local IP address */ 286 if (options.bind_address == NULL && !privileged) 287 return sock; 288 289 if (options.bind_address) { 290 memset(&hints, 0, sizeof(hints)); 291 hints.ai_family = ai->ai_family; 292 hints.ai_socktype = ai->ai_socktype; 293 hints.ai_protocol = ai->ai_protocol; 294 hints.ai_flags = AI_PASSIVE; 295 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); 296 if (gaierr) { 297 error("getaddrinfo: %s: %s", options.bind_address, 298 ssh_gai_strerror(gaierr)); 299 close(sock); 300 return -1; 301 } 302 } 303 /* 304 * If we are running as root and want to connect to a privileged 305 * port, bind our own socket to a privileged port. 306 */ 307 if (privileged) { 308 PRIV_START; 309 r = bindresvport_sa(sock, res ? res->ai_addr : NULL); 310 PRIV_END; 311 if (r < 0) { 312 error("bindresvport_sa: af=%d %s", ai->ai_family, 313 strerror(errno)); 314 goto fail; 315 } 316 } else { 317 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { 318 error("bind: %s: %s", options.bind_address, 319 strerror(errno)); 320 fail: 321 close(sock); 322 freeaddrinfo(res); 323 return -1; 324 } 325 } 326 if (res != NULL) 327 freeaddrinfo(res); 328 return sock; 329 } 330 331 static int 332 timeout_connect(int sockfd, const struct sockaddr *serv_addr, 333 socklen_t addrlen, int *timeoutp) 334 { 335 fd_set *fdset; 336 struct timeval tv, t_start; 337 socklen_t optlen; 338 int optval, rc, result = -1; 339 340 gettimeofday(&t_start, NULL); 341 342 if (*timeoutp <= 0) { 343 result = connect(sockfd, serv_addr, addrlen); 344 goto done; 345 } 346 347 set_nonblock(sockfd); 348 rc = connect(sockfd, serv_addr, addrlen); 349 if (rc == 0) { 350 unset_nonblock(sockfd); 351 result = 0; 352 goto done; 353 } 354 if (errno != EINPROGRESS) { 355 result = -1; 356 goto done; 357 } 358 359 fdset = xcalloc(howmany(sockfd + 1, NFDBITS), 360 sizeof(fd_mask)); 361 FD_SET(sockfd, fdset); 362 ms_to_timeval(&tv, *timeoutp); 363 364 for (;;) { 365 rc = select(sockfd + 1, NULL, fdset, NULL, &tv); 366 if (rc != -1 || errno != EINTR) 367 break; 368 } 369 370 switch (rc) { 371 case 0: 372 /* Timed out */ 373 errno = ETIMEDOUT; 374 break; 375 case -1: 376 /* Select error */ 377 debug("select: %s", strerror(errno)); 378 break; 379 case 1: 380 /* Completed or failed */ 381 optval = 0; 382 optlen = sizeof(optval); 383 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 384 &optlen) == -1) { 385 debug("getsockopt: %s", strerror(errno)); 386 break; 387 } 388 if (optval != 0) { 389 errno = optval; 390 break; 391 } 392 result = 0; 393 unset_nonblock(sockfd); 394 break; 395 default: 396 /* Should not occur */ 397 fatal("Bogus return (%d) from select()", rc); 398 } 399 400 free(fdset); 401 402 done: 403 if (result == 0 && *timeoutp > 0) { 404 ms_subtract_diff(&t_start, timeoutp); 405 if (*timeoutp <= 0) { 406 errno = ETIMEDOUT; 407 result = -1; 408 } 409 } 410 411 return (result); 412 } 413 414 /* 415 * Opens a TCP/IP connection to the remote server on the given host. 416 * The address of the remote host will be returned in hostaddr. 417 * If port is 0, the default port will be used. If needpriv is true, 418 * a privileged port will be allocated to make the connection. 419 * This requires super-user privileges if needpriv is true. 420 * Connection_attempts specifies the maximum number of tries (one per 421 * second). If proxy_command is non-NULL, it specifies the command (with %h 422 * and %p substituted for host and port, respectively) to use to contact 423 * the daemon. 424 */ 425 static int 426 ssh_connect_direct(const char *host, struct addrinfo *aitop, 427 struct sockaddr_storage *hostaddr, u_short port, int family, 428 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 429 { 430 int on = 1; 431 int sock = -1, attempt; 432 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 433 struct addrinfo *ai; 434 435 debug2("%s: needpriv %d", __func__, needpriv); 436 memset(ntop, 0, sizeof(ntop)); 437 memset(strport, 0, sizeof(strport)); 438 439 for (attempt = 0; attempt < connection_attempts; attempt++) { 440 if (attempt > 0) { 441 /* Sleep a moment before retrying. */ 442 sleep(1); 443 debug("Trying again..."); 444 } 445 /* 446 * Loop through addresses for this host, and try each one in 447 * sequence until the connection succeeds. 448 */ 449 for (ai = aitop; ai; ai = ai->ai_next) { 450 if (ai->ai_family != AF_INET && 451 ai->ai_family != AF_INET6) 452 continue; 453 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 454 ntop, sizeof(ntop), strport, sizeof(strport), 455 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 456 error("%s: getnameinfo failed", __func__); 457 continue; 458 } 459 debug("Connecting to %.200s [%.100s] port %s.", 460 host, ntop, strport); 461 462 /* Create a socket for connecting. */ 463 sock = ssh_create_socket(needpriv, ai); 464 if (sock < 0) 465 /* Any error is already output */ 466 continue; 467 468 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 469 timeout_ms) >= 0) { 470 /* Successful connection. */ 471 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 472 break; 473 } else { 474 debug("connect to address %s port %s: %s", 475 ntop, strport, strerror(errno)); 476 close(sock); 477 sock = -1; 478 } 479 } 480 if (sock != -1) 481 break; /* Successful connection. */ 482 } 483 484 /* Return failure if we didn't get a successful connection. */ 485 if (sock == -1) { 486 error("ssh: connect to host %s port %s: %s", 487 host, strport, strerror(errno)); 488 return (-1); 489 } 490 491 debug("Connection established."); 492 493 /* Set SO_KEEPALIVE if requested. */ 494 if (want_keepalive && 495 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 496 sizeof(on)) < 0) 497 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 498 499 /* Set the connection. */ 500 packet_set_connection(sock, sock); 501 502 return 0; 503 } 504 505 int 506 ssh_connect(const char *host, struct addrinfo *addrs, 507 struct sockaddr_storage *hostaddr, u_short port, int family, 508 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv) 509 { 510 if (options.proxy_command == NULL) { 511 return ssh_connect_direct(host, addrs, hostaddr, port, family, 512 connection_attempts, timeout_ms, want_keepalive, needpriv); 513 } else if (strcmp(options.proxy_command, "-") == 0) { 514 packet_set_connection(STDIN_FILENO, STDOUT_FILENO); 515 return 0; /* Always succeeds */ 516 } else if (options.proxy_use_fdpass) { 517 return ssh_proxy_fdpass_connect(host, port, 518 options.proxy_command); 519 } 520 return ssh_proxy_connect(host, port, options.proxy_command); 521 } 522 523 static void 524 send_client_banner(int connection_out, int minor1) 525 { 526 /* Send our own protocol version identification. */ 527 if (compat20) { 528 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n", 529 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION); 530 } else { 531 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n", 532 PROTOCOL_MAJOR_1, minor1, SSH_VERSION); 533 } 534 if (atomicio(vwrite, connection_out, client_version_string, 535 strlen(client_version_string)) != strlen(client_version_string)) 536 fatal("write: %.100s", strerror(errno)); 537 chop(client_version_string); 538 debug("Local version string %.100s", client_version_string); 539 } 540 541 /* 542 * Waits for the server identification string, and sends our own 543 * identification string. 544 */ 545 void 546 ssh_exchange_identification(int timeout_ms) 547 { 548 char buf[256], remote_version[256]; /* must be same size! */ 549 int remote_major, remote_minor, mismatch; 550 int connection_in = packet_get_connection_in(); 551 int connection_out = packet_get_connection_out(); 552 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0; 553 u_int i, n; 554 size_t len; 555 int fdsetsz, remaining, rc; 556 struct timeval t_start, t_remaining; 557 fd_set *fdset; 558 559 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); 560 fdset = xcalloc(1, fdsetsz); 561 562 /* 563 * If we are SSH2-only then we can send the banner immediately and 564 * save a round-trip. 565 */ 566 if (options.protocol == SSH_PROTO_2) { 567 enable_compat20(); 568 send_client_banner(connection_out, 0); 569 client_banner_sent = 1; 570 } 571 572 /* Read other side's version identification. */ 573 remaining = timeout_ms; 574 for (n = 0;;) { 575 for (i = 0; i < sizeof(buf) - 1; i++) { 576 if (timeout_ms > 0) { 577 gettimeofday(&t_start, NULL); 578 ms_to_timeval(&t_remaining, remaining); 579 FD_SET(connection_in, fdset); 580 rc = select(connection_in + 1, fdset, NULL, 581 fdset, &t_remaining); 582 ms_subtract_diff(&t_start, &remaining); 583 if (rc == 0 || remaining <= 0) 584 fatal("Connection timed out during " 585 "banner exchange"); 586 if (rc == -1) { 587 if (errno == EINTR) 588 continue; 589 fatal("ssh_exchange_identification: " 590 "select: %s", strerror(errno)); 591 } 592 } 593 594 len = atomicio(read, connection_in, &buf[i], 1); 595 596 if (len != 1 && errno == EPIPE) 597 fatal("ssh_exchange_identification: " 598 "Connection closed by remote host"); 599 else if (len != 1) 600 fatal("ssh_exchange_identification: " 601 "read: %.100s", strerror(errno)); 602 if (buf[i] == '\r') { 603 buf[i] = '\n'; 604 buf[i + 1] = 0; 605 continue; /**XXX wait for \n */ 606 } 607 if (buf[i] == '\n') { 608 buf[i + 1] = 0; 609 break; 610 } 611 if (++n > 65536) 612 fatal("ssh_exchange_identification: " 613 "No banner received"); 614 } 615 buf[sizeof(buf) - 1] = 0; 616 if (strncmp(buf, "SSH-", 4) == 0) 617 break; 618 debug("ssh_exchange_identification: %s", buf); 619 } 620 server_version_string = xstrdup(buf); 621 free(fdset); 622 623 /* 624 * Check that the versions match. In future this might accept 625 * several versions and set appropriate flags to handle them. 626 */ 627 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", 628 &remote_major, &remote_minor, remote_version) != 3) 629 fatal("Bad remote protocol version identification: '%.100s'", buf); 630 debug("Remote protocol version %d.%d, remote software version %.100s", 631 remote_major, remote_minor, remote_version); 632 633 active_state->compat = compat_datafellows(remote_version); 634 mismatch = 0; 635 636 switch (remote_major) { 637 case 1: 638 if (remote_minor == 99 && 639 (options.protocol & SSH_PROTO_2) && 640 !(options.protocol & SSH_PROTO_1_PREFERRED)) { 641 enable_compat20(); 642 break; 643 } 644 if (!(options.protocol & SSH_PROTO_1)) { 645 mismatch = 1; 646 break; 647 } 648 if (remote_minor < 3) { 649 fatal("Remote machine has too old SSH software version."); 650 } else if (remote_minor == 3 || remote_minor == 4) { 651 /* We speak 1.3, too. */ 652 enable_compat13(); 653 minor1 = 3; 654 if (options.forward_agent) { 655 logit("Agent forwarding disabled for protocol 1.3"); 656 options.forward_agent = 0; 657 } 658 } 659 break; 660 case 2: 661 if (options.protocol & SSH_PROTO_2) { 662 enable_compat20(); 663 break; 664 } 665 /* FALLTHROUGH */ 666 default: 667 mismatch = 1; 668 break; 669 } 670 if (mismatch) 671 fatal("Protocol major versions differ: %d vs. %d", 672 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, 673 remote_major); 674 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) 675 fatal("Server version \"%.100s\" uses unsafe key agreement; " 676 "refusing connection", remote_version); 677 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) 678 logit("Server version \"%.100s\" uses unsafe RSA signature " 679 "scheme; disabling use of RSA keys", remote_version); 680 if (!client_banner_sent) 681 send_client_banner(connection_out, minor1); 682 chop(server_version_string); 683 } 684 685 /* defaults to 'no' */ 686 static int 687 confirm(const char *prompt) 688 { 689 const char *msg, *again = "Please type 'yes' or 'no': "; 690 char *p; 691 int ret = -1; 692 693 if (options.batch_mode) 694 return 0; 695 for (msg = prompt;;msg = again) { 696 p = read_passphrase(msg, RP_ECHO); 697 if (p == NULL || 698 (p[0] == '\0') || (p[0] == '\n') || 699 strncasecmp(p, "no", 2) == 0) 700 ret = 0; 701 if (p && strncasecmp(p, "yes", 3) == 0) 702 ret = 1; 703 free(p); 704 if (ret != -1) 705 return ret; 706 } 707 } 708 709 static int 710 check_host_cert(const char *host, const Key *host_key) 711 { 712 const char *reason; 713 714 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { 715 error("%s", reason); 716 return 0; 717 } 718 if (buffer_len(host_key->cert->critical) != 0) { 719 error("Certificate for %s contains unsupported " 720 "critical options(s)", host); 721 return 0; 722 } 723 return 1; 724 } 725 726 static int 727 sockaddr_is_local(struct sockaddr *hostaddr) 728 { 729 switch (hostaddr->sa_family) { 730 case AF_INET: 731 return (ntohl(((struct sockaddr_in *)hostaddr)-> 732 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 733 case AF_INET6: 734 return IN6_IS_ADDR_LOOPBACK( 735 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 736 default: 737 return 0; 738 } 739 } 740 741 /* 742 * Prepare the hostname and ip address strings that are used to lookup 743 * host keys in known_hosts files. These may have a port number appended. 744 */ 745 void 746 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 747 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 748 { 749 char ntop[NI_MAXHOST]; 750 socklen_t addrlen; 751 752 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 753 case -1: 754 addrlen = 0; 755 break; 756 case AF_INET: 757 addrlen = sizeof(struct sockaddr_in); 758 break; 759 case AF_INET6: 760 addrlen = sizeof(struct sockaddr_in6); 761 break; 762 default: 763 addrlen = sizeof(struct sockaddr); 764 break; 765 } 766 767 /* 768 * We don't have the remote ip-address for connections 769 * using a proxy command 770 */ 771 if (hostfile_ipaddr != NULL) { 772 if (options.proxy_command == NULL) { 773 if (getnameinfo(hostaddr, addrlen, 774 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 775 fatal("%s: getnameinfo failed", __func__); 776 *hostfile_ipaddr = put_host_port(ntop, port); 777 } else { 778 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 779 "command>"); 780 } 781 } 782 783 /* 784 * Allow the user to record the key under a different name or 785 * differentiate a non-standard port. This is useful for ssh 786 * tunneling over forwarded connections or if you run multiple 787 * sshd's on different ports on the same machine. 788 */ 789 if (hostfile_hostname != NULL) { 790 if (options.host_key_alias != NULL) { 791 *hostfile_hostname = xstrdup(options.host_key_alias); 792 debug("using hostkeyalias: %s", *hostfile_hostname); 793 } else { 794 *hostfile_hostname = put_host_port(hostname, port); 795 } 796 } 797 } 798 799 /* 800 * check whether the supplied host key is valid, return -1 if the key 801 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 802 */ 803 #define RDRW 0 804 #define RDONLY 1 805 #define ROQUIET 2 806 static int 807 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 808 Key *host_key, int readonly, 809 char **user_hostfiles, u_int num_user_hostfiles, 810 char **system_hostfiles, u_int num_system_hostfiles) 811 { 812 HostStatus host_status; 813 HostStatus ip_status; 814 Key *raw_key = NULL; 815 char *ip = NULL, *host = NULL; 816 char hostline[1000], *hostp, *fp, *ra; 817 char msg[1024]; 818 const char *type; 819 const struct hostkey_entry *host_found, *ip_found; 820 int len, cancelled_forwarding = 0; 821 int local = sockaddr_is_local(hostaddr); 822 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; 823 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 824 struct hostkeys *host_hostkeys, *ip_hostkeys; 825 u_int i; 826 827 /* 828 * Force accepting of the host key for loopback/localhost. The 829 * problem is that if the home directory is NFS-mounted to multiple 830 * machines, localhost will refer to a different machine in each of 831 * them, and the user will get bogus HOST_CHANGED warnings. This 832 * essentially disables host authentication for localhost; however, 833 * this is probably not a real problem. 834 */ 835 if (options.no_host_authentication_for_localhost == 1 && local && 836 options.host_key_alias == NULL) { 837 debug("Forcing accepting of host key for " 838 "loopback/localhost."); 839 return 0; 840 } 841 842 /* 843 * Prepare the hostname and address strings used for hostkey lookup. 844 * In some cases, these will have a port number appended. 845 */ 846 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 847 848 /* 849 * Turn off check_host_ip if the connection is to localhost, via proxy 850 * command or if we don't have a hostname to compare with 851 */ 852 if (options.check_host_ip && (local || 853 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 854 options.check_host_ip = 0; 855 856 host_hostkeys = init_hostkeys(); 857 for (i = 0; i < num_user_hostfiles; i++) 858 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 859 for (i = 0; i < num_system_hostfiles; i++) 860 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 861 862 ip_hostkeys = NULL; 863 if (!want_cert && options.check_host_ip) { 864 ip_hostkeys = init_hostkeys(); 865 for (i = 0; i < num_user_hostfiles; i++) 866 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 867 for (i = 0; i < num_system_hostfiles; i++) 868 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 869 } 870 871 retry: 872 /* Reload these as they may have changed on cert->key downgrade */ 873 want_cert = key_is_cert(host_key); 874 type = key_type(host_key); 875 876 /* 877 * Check if the host key is present in the user's list of known 878 * hosts or in the systemwide list. 879 */ 880 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 881 &host_found); 882 883 /* 884 * Also perform check for the ip address, skip the check if we are 885 * localhost, looking for a certificate, or the hostname was an ip 886 * address to begin with. 887 */ 888 if (!want_cert && ip_hostkeys != NULL) { 889 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 890 &ip_found); 891 if (host_status == HOST_CHANGED && 892 (ip_status != HOST_CHANGED || 893 (ip_found != NULL && 894 !key_equal(ip_found->key, host_found->key)))) 895 host_ip_differ = 1; 896 } else 897 ip_status = host_status; 898 899 switch (host_status) { 900 case HOST_OK: 901 /* The host is known and the key matches. */ 902 debug("Host '%.200s' is known and matches the %s host %s.", 903 host, type, want_cert ? "certificate" : "key"); 904 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 905 host_found->file, host_found->line); 906 if (want_cert && !check_host_cert(hostname, host_key)) 907 goto fail; 908 if (options.check_host_ip && ip_status == HOST_NEW) { 909 if (readonly || want_cert) 910 logit("%s host key for IP address " 911 "'%.128s' not in list of known hosts.", 912 type, ip); 913 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 914 host_key, options.hash_known_hosts)) 915 logit("Failed to add the %s host key for IP " 916 "address '%.128s' to the list of known " 917 "hosts (%.500s).", type, ip, 918 user_hostfiles[0]); 919 else 920 logit("Warning: Permanently added the %s host " 921 "key for IP address '%.128s' to the list " 922 "of known hosts.", type, ip); 923 } else if (options.visual_host_key) { 924 fp = sshkey_fingerprint(host_key, 925 options.fingerprint_hash, SSH_FP_DEFAULT); 926 ra = sshkey_fingerprint(host_key, 927 options.fingerprint_hash, SSH_FP_RANDOMART); 928 if (fp == NULL || ra == NULL) 929 fatal("%s: sshkey_fingerprint fail", __func__); 930 logit("Host key fingerprint is %s\n%s", fp, ra); 931 free(ra); 932 free(fp); 933 } 934 hostkey_trusted = 1; 935 break; 936 case HOST_NEW: 937 if (options.host_key_alias == NULL && port != 0 && 938 port != SSH_DEFAULT_PORT) { 939 debug("checking without port identifier"); 940 if (check_host_key(hostname, hostaddr, 0, host_key, 941 ROQUIET, user_hostfiles, num_user_hostfiles, 942 system_hostfiles, num_system_hostfiles) == 0) { 943 debug("found matching key w/out port"); 944 break; 945 } 946 } 947 if (readonly || want_cert) 948 goto fail; 949 /* The host is new. */ 950 if (options.strict_host_key_checking == 1) { 951 /* 952 * User has requested strict host key checking. We 953 * will not add the host key automatically. The only 954 * alternative left is to abort. 955 */ 956 error("No %s host key is known for %.200s and you " 957 "have requested strict checking.", type, host); 958 goto fail; 959 } else if (options.strict_host_key_checking == 2) { 960 char msg1[1024], msg2[1024]; 961 962 if (show_other_keys(host_hostkeys, host_key)) 963 snprintf(msg1, sizeof(msg1), 964 "\nbut keys of different type are already" 965 " known for this host."); 966 else 967 snprintf(msg1, sizeof(msg1), "."); 968 /* The default */ 969 fp = sshkey_fingerprint(host_key, 970 options.fingerprint_hash, SSH_FP_DEFAULT); 971 ra = sshkey_fingerprint(host_key, 972 options.fingerprint_hash, SSH_FP_RANDOMART); 973 if (fp == NULL || ra == NULL) 974 fatal("%s: sshkey_fingerprint fail", __func__); 975 msg2[0] = '\0'; 976 if (options.verify_host_key_dns) { 977 if (matching_host_key_dns) 978 snprintf(msg2, sizeof(msg2), 979 "Matching host key fingerprint" 980 " found in DNS.\n"); 981 else 982 snprintf(msg2, sizeof(msg2), 983 "No matching host key fingerprint" 984 " found in DNS.\n"); 985 } 986 snprintf(msg, sizeof(msg), 987 "The authenticity of host '%.200s (%s)' can't be " 988 "established%s\n" 989 "%s key fingerprint is %s.%s%s\n%s" 990 "Are you sure you want to continue connecting " 991 "(yes/no)? ", 992 host, ip, msg1, type, fp, 993 options.visual_host_key ? "\n" : "", 994 options.visual_host_key ? ra : "", 995 msg2); 996 free(ra); 997 free(fp); 998 if (!confirm(msg)) 999 goto fail; 1000 hostkey_trusted = 1; /* user explicitly confirmed */ 1001 } 1002 /* 1003 * If not in strict mode, add the key automatically to the 1004 * local known_hosts file. 1005 */ 1006 if (options.check_host_ip && ip_status == HOST_NEW) { 1007 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 1008 hostp = hostline; 1009 if (options.hash_known_hosts) { 1010 /* Add hash of host and IP separately */ 1011 r = add_host_to_hostfile(user_hostfiles[0], 1012 host, host_key, options.hash_known_hosts) && 1013 add_host_to_hostfile(user_hostfiles[0], ip, 1014 host_key, options.hash_known_hosts); 1015 } else { 1016 /* Add unhashed "host,ip" */ 1017 r = add_host_to_hostfile(user_hostfiles[0], 1018 hostline, host_key, 1019 options.hash_known_hosts); 1020 } 1021 } else { 1022 r = add_host_to_hostfile(user_hostfiles[0], host, 1023 host_key, options.hash_known_hosts); 1024 hostp = host; 1025 } 1026 1027 if (!r) 1028 logit("Failed to add the host to the list of known " 1029 "hosts (%.500s).", user_hostfiles[0]); 1030 else 1031 logit("Warning: Permanently added '%.200s' (%s) to the " 1032 "list of known hosts.", hostp, type); 1033 break; 1034 case HOST_REVOKED: 1035 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1036 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 1037 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1038 error("The %s host key for %s is marked as revoked.", type, host); 1039 error("This could mean that a stolen key is being used to"); 1040 error("impersonate this host."); 1041 1042 /* 1043 * If strict host key checking is in use, the user will have 1044 * to edit the key manually and we can only abort. 1045 */ 1046 if (options.strict_host_key_checking) { 1047 error("%s host key for %.200s was revoked and you have " 1048 "requested strict checking.", type, host); 1049 goto fail; 1050 } 1051 goto continue_unsafe; 1052 1053 case HOST_CHANGED: 1054 if (want_cert) { 1055 /* 1056 * This is only a debug() since it is valid to have 1057 * CAs with wildcard DNS matches that don't match 1058 * all hosts that one might visit. 1059 */ 1060 debug("Host certificate authority does not " 1061 "match %s in %s:%lu", CA_MARKER, 1062 host_found->file, host_found->line); 1063 goto fail; 1064 } 1065 if (readonly == ROQUIET) 1066 goto fail; 1067 if (options.check_host_ip && host_ip_differ) { 1068 char *key_msg; 1069 if (ip_status == HOST_NEW) 1070 key_msg = "is unknown"; 1071 else if (ip_status == HOST_OK) 1072 key_msg = "is unchanged"; 1073 else 1074 key_msg = "has a different value"; 1075 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1076 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 1077 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1078 error("The %s host key for %s has changed,", type, host); 1079 error("and the key for the corresponding IP address %s", ip); 1080 error("%s. This could either mean that", key_msg); 1081 error("DNS SPOOFING is happening or the IP address for the host"); 1082 error("and its host key have changed at the same time."); 1083 if (ip_status != HOST_NEW) 1084 error("Offending key for IP in %s:%lu", 1085 ip_found->file, ip_found->line); 1086 } 1087 /* The host key has changed. */ 1088 warn_changed_key(host_key); 1089 error("Add correct host key in %.100s to get rid of this message.", 1090 user_hostfiles[0]); 1091 error("Offending %s key in %s:%lu", key_type(host_found->key), 1092 host_found->file, host_found->line); 1093 1094 /* 1095 * If strict host key checking is in use, the user will have 1096 * to edit the key manually and we can only abort. 1097 */ 1098 if (options.strict_host_key_checking) { 1099 error("%s host key for %.200s has changed and you have " 1100 "requested strict checking.", type, host); 1101 goto fail; 1102 } 1103 1104 continue_unsafe: 1105 /* 1106 * If strict host key checking has not been requested, allow 1107 * the connection but without MITM-able authentication or 1108 * forwarding. 1109 */ 1110 if (options.password_authentication) { 1111 error("Password authentication is disabled to avoid " 1112 "man-in-the-middle attacks."); 1113 options.password_authentication = 0; 1114 cancelled_forwarding = 1; 1115 } 1116 if (options.kbd_interactive_authentication) { 1117 error("Keyboard-interactive authentication is disabled" 1118 " to avoid man-in-the-middle attacks."); 1119 options.kbd_interactive_authentication = 0; 1120 options.challenge_response_authentication = 0; 1121 cancelled_forwarding = 1; 1122 } 1123 if (options.challenge_response_authentication) { 1124 error("Challenge/response authentication is disabled" 1125 " to avoid man-in-the-middle attacks."); 1126 options.challenge_response_authentication = 0; 1127 cancelled_forwarding = 1; 1128 } 1129 if (options.forward_agent) { 1130 error("Agent forwarding is disabled to avoid " 1131 "man-in-the-middle attacks."); 1132 options.forward_agent = 0; 1133 cancelled_forwarding = 1; 1134 } 1135 if (options.forward_x11) { 1136 error("X11 forwarding is disabled to avoid " 1137 "man-in-the-middle attacks."); 1138 options.forward_x11 = 0; 1139 cancelled_forwarding = 1; 1140 } 1141 if (options.num_local_forwards > 0 || 1142 options.num_remote_forwards > 0) { 1143 error("Port forwarding is disabled to avoid " 1144 "man-in-the-middle attacks."); 1145 options.num_local_forwards = 1146 options.num_remote_forwards = 0; 1147 cancelled_forwarding = 1; 1148 } 1149 if (options.tun_open != SSH_TUNMODE_NO) { 1150 error("Tunnel forwarding is disabled to avoid " 1151 "man-in-the-middle attacks."); 1152 options.tun_open = SSH_TUNMODE_NO; 1153 cancelled_forwarding = 1; 1154 } 1155 if (options.exit_on_forward_failure && cancelled_forwarding) 1156 fatal("Error: forwarding disabled due to host key " 1157 "check failure"); 1158 1159 /* 1160 * XXX Should permit the user to change to use the new id. 1161 * This could be done by converting the host key to an 1162 * identifying sentence, tell that the host identifies itself 1163 * by that sentence, and ask the user if he/she wishes to 1164 * accept the authentication. 1165 */ 1166 break; 1167 case HOST_FOUND: 1168 fatal("internal error"); 1169 break; 1170 } 1171 1172 if (options.check_host_ip && host_status != HOST_CHANGED && 1173 ip_status == HOST_CHANGED) { 1174 snprintf(msg, sizeof(msg), 1175 "Warning: the %s host key for '%.200s' " 1176 "differs from the key for the IP address '%.128s'" 1177 "\nOffending key for IP in %s:%lu", 1178 type, host, ip, ip_found->file, ip_found->line); 1179 if (host_status == HOST_OK) { 1180 len = strlen(msg); 1181 snprintf(msg + len, sizeof(msg) - len, 1182 "\nMatching host key in %s:%lu", 1183 host_found->file, host_found->line); 1184 } 1185 if (options.strict_host_key_checking == 1) { 1186 logit("%s", msg); 1187 error("Exiting, you have requested strict checking."); 1188 goto fail; 1189 } else if (options.strict_host_key_checking == 2) { 1190 strlcat(msg, "\nAre you sure you want " 1191 "to continue connecting (yes/no)? ", sizeof(msg)); 1192 if (!confirm(msg)) 1193 goto fail; 1194 } else { 1195 logit("%s", msg); 1196 } 1197 } 1198 1199 if (!hostkey_trusted && options.update_hostkeys) { 1200 debug("%s: hostkey not known or explicitly trusted: " 1201 "disabling UpdateHostkeys", __func__); 1202 options.update_hostkeys = 0; 1203 } 1204 1205 free(ip); 1206 free(host); 1207 if (host_hostkeys != NULL) 1208 free_hostkeys(host_hostkeys); 1209 if (ip_hostkeys != NULL) 1210 free_hostkeys(ip_hostkeys); 1211 return 0; 1212 1213 fail: 1214 if (want_cert && host_status != HOST_REVOKED) { 1215 /* 1216 * No matching certificate. Downgrade cert to raw key and 1217 * search normally. 1218 */ 1219 debug("No matching CA found. Retry with plain key"); 1220 raw_key = key_from_private(host_key); 1221 if (key_drop_cert(raw_key) != 0) 1222 fatal("Couldn't drop certificate"); 1223 host_key = raw_key; 1224 goto retry; 1225 } 1226 if (raw_key != NULL) 1227 key_free(raw_key); 1228 free(ip); 1229 free(host); 1230 if (host_hostkeys != NULL) 1231 free_hostkeys(host_hostkeys); 1232 if (ip_hostkeys != NULL) 1233 free_hostkeys(ip_hostkeys); 1234 return -1; 1235 } 1236 1237 /* returns 0 if key verifies or -1 if key does NOT verify */ 1238 int 1239 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) 1240 { 1241 u_int i; 1242 int r = -1, flags = 0; 1243 char valid[64], *fp = NULL, *cafp = NULL; 1244 struct sshkey *plain = NULL; 1245 1246 if ((fp = sshkey_fingerprint(host_key, 1247 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1248 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1249 r = -1; 1250 goto out; 1251 } 1252 1253 if (sshkey_is_cert(host_key)) { 1254 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1255 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1256 error("%s: fingerprint CA key: %s", 1257 __func__, ssh_err(r)); 1258 r = -1; 1259 goto out; 1260 } 1261 sshkey_format_cert_validity(host_key->cert, 1262 valid, sizeof(valid)); 1263 debug("Server host certificate: %s %s, serial %llu " 1264 "ID \"%s\" CA %s %s valid %s", 1265 sshkey_ssh_name(host_key), fp, 1266 (unsigned long long)host_key->cert->serial, 1267 host_key->cert->key_id, 1268 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1269 valid); 1270 for (i = 0; i < host_key->cert->nprincipals; i++) { 1271 debug2("Server host certificate hostname: %s", 1272 host_key->cert->principals[i]); 1273 } 1274 } else { 1275 debug("Server host key: %s %s", compat20 ? 1276 sshkey_ssh_name(host_key) : sshkey_type(host_key), fp); 1277 } 1278 1279 if (sshkey_equal(previous_host_key, host_key)) { 1280 debug2("%s: server host key %s %s matches cached key", 1281 __func__, sshkey_type(host_key), fp); 1282 r = 0; 1283 goto out; 1284 } 1285 1286 /* Check in RevokedHostKeys file if specified */ 1287 if (options.revoked_host_keys != NULL) { 1288 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1289 switch (r) { 1290 case 0: 1291 break; /* not revoked */ 1292 case SSH_ERR_KEY_REVOKED: 1293 error("Host key %s %s revoked by file %s", 1294 sshkey_type(host_key), fp, 1295 options.revoked_host_keys); 1296 r = -1; 1297 goto out; 1298 default: 1299 error("Error checking host key %s %s in " 1300 "revoked keys file %s: %s", sshkey_type(host_key), 1301 fp, options.revoked_host_keys, ssh_err(r)); 1302 r = -1; 1303 goto out; 1304 } 1305 } 1306 1307 if (options.verify_host_key_dns) { 1308 /* 1309 * XXX certs are not yet supported for DNS, so downgrade 1310 * them and try the plain key. 1311 */ 1312 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1313 goto out; 1314 if (sshkey_is_cert(plain)) 1315 sshkey_drop_cert(plain); 1316 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1317 if (flags & DNS_VERIFY_FOUND) { 1318 if (options.verify_host_key_dns == 1 && 1319 flags & DNS_VERIFY_MATCH && 1320 flags & DNS_VERIFY_SECURE) { 1321 r = 0; 1322 goto out; 1323 } 1324 if (flags & DNS_VERIFY_MATCH) { 1325 matching_host_key_dns = 1; 1326 } else { 1327 warn_changed_key(plain); 1328 error("Update the SSHFP RR in DNS " 1329 "with the new host key to get rid " 1330 "of this message."); 1331 } 1332 } 1333 } 1334 } 1335 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1336 options.user_hostfiles, options.num_user_hostfiles, 1337 options.system_hostfiles, options.num_system_hostfiles); 1338 1339 out: 1340 sshkey_free(plain); 1341 free(fp); 1342 free(cafp); 1343 if (r == 0 && host_key != NULL) { 1344 key_free(previous_host_key); 1345 previous_host_key = key_from_private(host_key); 1346 } 1347 1348 return r; 1349 } 1350 1351 /* 1352 * Starts a dialog with the server, and authenticates the current user on the 1353 * server. This does not need any extra privileges. The basic connection 1354 * to the server must already have been established before this is called. 1355 * If login fails, this function prints an error and never returns. 1356 * This function does not require super-user privileges. 1357 */ 1358 void 1359 ssh_login(Sensitive *sensitive, const char *orighost, 1360 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1361 { 1362 char *host; 1363 char *server_user, *local_user; 1364 1365 local_user = xstrdup(pw->pw_name); 1366 server_user = options.user ? options.user : local_user; 1367 1368 /* Convert the user-supplied hostname into all lowercase. */ 1369 host = xstrdup(orighost); 1370 lowercase(host); 1371 1372 /* Exchange protocol version identification strings with the server. */ 1373 ssh_exchange_identification(timeout_ms); 1374 1375 /* Put the connection into non-blocking mode. */ 1376 packet_set_nonblocking(); 1377 1378 /* key exchange */ 1379 /* authenticate user */ 1380 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1381 if (compat20) { 1382 ssh_kex2(host, hostaddr, port); 1383 ssh_userauth2(local_user, server_user, host, sensitive); 1384 } else { 1385 #ifdef WITH_SSH1 1386 ssh_kex(host, hostaddr); 1387 ssh_userauth1(local_user, server_user, host, sensitive); 1388 #else 1389 fatal("ssh1 is not supported"); 1390 #endif 1391 } 1392 free(local_user); 1393 } 1394 1395 void 1396 ssh_put_password(char *password) 1397 { 1398 int size; 1399 char *padded; 1400 1401 if (datafellows & SSH_BUG_PASSWORDPAD) { 1402 packet_put_cstring(password); 1403 return; 1404 } 1405 size = ROUNDUP(strlen(password) + 1, 32); 1406 padded = xcalloc(1, size); 1407 strlcpy(padded, password, size); 1408 packet_put_string(padded, size); 1409 explicit_bzero(padded, size); 1410 free(padded); 1411 } 1412 1413 /* print all known host keys for a given host, but skip keys of given type */ 1414 static int 1415 show_other_keys(struct hostkeys *hostkeys, Key *key) 1416 { 1417 int type[] = { 1418 KEY_RSA1, 1419 KEY_RSA, 1420 KEY_DSA, 1421 KEY_ECDSA, 1422 KEY_ED25519, 1423 -1 1424 }; 1425 int i, ret = 0; 1426 char *fp, *ra; 1427 const struct hostkey_entry *found; 1428 1429 for (i = 0; type[i] != -1; i++) { 1430 if (type[i] == key->type) 1431 continue; 1432 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1433 continue; 1434 fp = sshkey_fingerprint(found->key, 1435 options.fingerprint_hash, SSH_FP_DEFAULT); 1436 ra = sshkey_fingerprint(found->key, 1437 options.fingerprint_hash, SSH_FP_RANDOMART); 1438 if (fp == NULL || ra == NULL) 1439 fatal("%s: sshkey_fingerprint fail", __func__); 1440 logit("WARNING: %s key found for host %s\n" 1441 "in %s:%lu\n" 1442 "%s key fingerprint %s.", 1443 key_type(found->key), 1444 found->host, found->file, found->line, 1445 key_type(found->key), fp); 1446 if (options.visual_host_key) 1447 logit("%s", ra); 1448 free(ra); 1449 free(fp); 1450 ret = 1; 1451 } 1452 return ret; 1453 } 1454 1455 static void 1456 warn_changed_key(Key *host_key) 1457 { 1458 char *fp; 1459 1460 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1461 SSH_FP_DEFAULT); 1462 if (fp == NULL) 1463 fatal("%s: sshkey_fingerprint fail", __func__); 1464 1465 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1466 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1467 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1468 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1469 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1470 error("It is also possible that a host key has just been changed."); 1471 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1472 key_type(host_key), fp); 1473 error("Please contact your system administrator."); 1474 1475 free(fp); 1476 } 1477 1478 /* 1479 * Execute a local command 1480 */ 1481 int 1482 ssh_local_cmd(const char *args) 1483 { 1484 char *shell; 1485 pid_t pid; 1486 int status; 1487 void (*osighand)(int); 1488 1489 if (!options.permit_local_command || 1490 args == NULL || !*args) 1491 return (1); 1492 1493 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1494 shell = _PATH_BSHELL; 1495 1496 osighand = signal(SIGCHLD, SIG_DFL); 1497 pid = fork(); 1498 if (pid == 0) { 1499 signal(SIGPIPE, SIG_DFL); 1500 debug3("Executing %s -c \"%s\"", shell, args); 1501 execl(shell, shell, "-c", args, (char *)NULL); 1502 error("Couldn't execute %s -c \"%s\": %s", 1503 shell, args, strerror(errno)); 1504 _exit(1); 1505 } else if (pid == -1) 1506 fatal("fork failed: %.100s", strerror(errno)); 1507 while (waitpid(pid, &status, 0) == -1) 1508 if (errno != EINTR) 1509 fatal("Couldn't wait for child: %s", strerror(errno)); 1510 signal(SIGCHLD, osighand); 1511 1512 if (!WIFEXITED(status)) 1513 return (1); 1514 1515 return (WEXITSTATUS(status)); 1516 } 1517 1518 void 1519 maybe_add_key_to_agent(char *authfile, Key *private, char *comment, 1520 char *passphrase) 1521 { 1522 int auth_sock = -1, r; 1523 1524 if (options.add_keys_to_agent == 0) 1525 return; 1526 1527 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1528 debug3("no authentication agent, not adding key"); 1529 return; 1530 } 1531 1532 if (options.add_keys_to_agent == 2 && 1533 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1534 debug3("user denied adding this key"); 1535 close(auth_sock); 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 close(auth_sock); 1545 } 1546
