Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame^] | 1 | /* $OpenBSD: sshconnect.c,v 1.234 2011/05/24 07:15:47 djm Exp $ */ |
| 2 | /* |
| 3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 5 | * All rights reserved |
| 6 | * Code to connect to a remote host, and to perform the client side of the |
| 7 | * login (authentication) dialog. |
| 8 | * |
| 9 | * As far as I am concerned, the code I have written for this software |
| 10 | * can be used freely for any purpose. Any derived versions of this |
| 11 | * software must be clearly marked as such, and if the derived work is |
| 12 | * incompatible with the protocol description in the RFC file, it must be |
| 13 | * called by a name other than "ssh" or "Secure Shell". |
| 14 | */ |
| 15 | |
| 16 | #include "includes.h" |
| 17 | |
| 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 "readconf.h" |
| 58 | #include "atomicio.h" |
| 59 | #include "misc.h" |
| 60 | #include "dns.h" |
| 61 | #include "roaming.h" |
| 62 | #include "ssh2.h" |
| 63 | #include "version.h" |
| 64 | |
| 65 | char *client_version_string = NULL; |
| 66 | char *server_version_string = NULL; |
| 67 | |
| 68 | static int matching_host_key_dns = 0; |
| 69 | |
| 70 | static pid_t proxy_command_pid = 0; |
| 71 | |
| 72 | /* import */ |
| 73 | extern Options options; |
| 74 | extern char *__progname; |
| 75 | extern uid_t original_real_uid; |
| 76 | extern uid_t original_effective_uid; |
| 77 | |
| 78 | static int show_other_keys(struct hostkeys *, Key *); |
| 79 | static void warn_changed_key(Key *); |
| 80 | |
| 81 | /* |
| 82 | * Connect to the given ssh server using a proxy command. |
| 83 | */ |
| 84 | static int |
| 85 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
| 86 | { |
| 87 | char *command_string, *tmp; |
| 88 | int pin[2], pout[2]; |
| 89 | pid_t pid; |
| 90 | char *shell, strport[NI_MAXSERV]; |
| 91 | |
| 92 | if ((shell = getenv("SHELL")) == NULL || *shell == '\0') |
| 93 | shell = _PATH_BSHELL; |
| 94 | |
| 95 | /* Convert the port number into a string. */ |
| 96 | snprintf(strport, sizeof strport, "%hu", port); |
| 97 | |
| 98 | /* |
| 99 | * Build the final command string in the buffer by making the |
| 100 | * appropriate substitutions to the given proxy command. |
| 101 | * |
| 102 | * Use "exec" to avoid "sh -c" processes on some platforms |
| 103 | * (e.g. Solaris) |
| 104 | */ |
| 105 | xasprintf(&tmp, "exec %s", proxy_command); |
| 106 | command_string = percent_expand(tmp, "h", host, "p", strport, |
| 107 | "r", options.user, (char *)NULL); |
| 108 | xfree(tmp); |
| 109 | |
| 110 | /* Create pipes for communicating with the proxy. */ |
| 111 | if (pipe(pin) < 0 || pipe(pout) < 0) |
| 112 | fatal("Could not create pipes to communicate with the proxy: %.100s", |
| 113 | strerror(errno)); |
| 114 | |
| 115 | debug("Executing proxy command: %.500s", command_string); |
| 116 | |
| 117 | /* Fork and execute the proxy command. */ |
| 118 | if ((pid = fork()) == 0) { |
| 119 | char *argv[10]; |
| 120 | |
| 121 | /* Child. Permanently give up superuser privileges. */ |
| 122 | permanently_drop_suid(original_real_uid); |
| 123 | |
| 124 | /* Redirect stdin and stdout. */ |
| 125 | close(pin[1]); |
| 126 | if (pin[0] != 0) { |
| 127 | if (dup2(pin[0], 0) < 0) |
| 128 | perror("dup2 stdin"); |
| 129 | close(pin[0]); |
| 130 | } |
| 131 | close(pout[0]); |
| 132 | if (dup2(pout[1], 1) < 0) |
| 133 | perror("dup2 stdout"); |
| 134 | /* Cannot be 1 because pin allocated two descriptors. */ |
| 135 | close(pout[1]); |
| 136 | |
| 137 | /* Stderr is left as it is so that error messages get |
| 138 | printed on the user's terminal. */ |
| 139 | argv[0] = shell; |
| 140 | argv[1] = "-c"; |
| 141 | argv[2] = command_string; |
| 142 | argv[3] = NULL; |
| 143 | |
| 144 | /* Execute the proxy command. Note that we gave up any |
| 145 | extra privileges above. */ |
| 146 | signal(SIGPIPE, SIG_DFL); |
| 147 | execv(argv[0], argv); |
| 148 | perror(argv[0]); |
| 149 | exit(1); |
| 150 | } |
| 151 | /* Parent. */ |
| 152 | if (pid < 0) |
| 153 | fatal("fork failed: %.100s", strerror(errno)); |
| 154 | else |
| 155 | proxy_command_pid = pid; /* save pid to clean up later */ |
| 156 | |
| 157 | /* Close child side of the descriptors. */ |
| 158 | close(pin[0]); |
| 159 | close(pout[1]); |
| 160 | |
| 161 | /* Free the command name. */ |
| 162 | xfree(command_string); |
| 163 | |
| 164 | /* Set the connection file descriptors. */ |
| 165 | packet_set_connection(pout[0], pin[1]); |
| 166 | packet_set_timeout(options.server_alive_interval, |
| 167 | options.server_alive_count_max); |
| 168 | |
| 169 | /* Indicate OK return */ |
| 170 | return 0; |
| 171 | } |
| 172 | |
| 173 | void |
| 174 | ssh_kill_proxy_command(void) |
| 175 | { |
| 176 | /* |
| 177 | * Send SIGHUP to proxy command if used. We don't wait() in |
| 178 | * case it hangs and instead rely on init to reap the child |
| 179 | */ |
| 180 | if (proxy_command_pid > 1) |
| 181 | kill(proxy_command_pid, SIGHUP); |
| 182 | } |
| 183 | |
| 184 | /* |
| 185 | * Creates a (possibly privileged) socket for use as the ssh connection. |
| 186 | */ |
| 187 | static int |
| 188 | ssh_create_socket(int privileged, struct addrinfo *ai) |
| 189 | { |
| 190 | int sock, gaierr; |
| 191 | struct addrinfo hints, *res; |
| 192 | |
| 193 | /* |
| 194 | * If we are running as root and want to connect to a privileged |
| 195 | * port, bind our own socket to a privileged port. |
| 196 | */ |
| 197 | if (privileged) { |
| 198 | int p = IPPORT_RESERVED - 1; |
| 199 | PRIV_START; |
| 200 | sock = rresvport_af(&p, ai->ai_family); |
| 201 | PRIV_END; |
| 202 | if (sock < 0) |
| 203 | error("rresvport: af=%d %.100s", ai->ai_family, |
| 204 | strerror(errno)); |
| 205 | else |
| 206 | debug("Allocated local port %d.", p); |
| 207 | return sock; |
| 208 | } |
| 209 | sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
| 210 | if (sock < 0) { |
| 211 | error("socket: %.100s", strerror(errno)); |
| 212 | return -1; |
| 213 | } |
| 214 | fcntl(sock, F_SETFD, FD_CLOEXEC); |
| 215 | |
| 216 | /* Bind the socket to an alternative local IP address */ |
| 217 | if (options.bind_address == NULL) |
| 218 | return sock; |
| 219 | |
| 220 | memset(&hints, 0, sizeof(hints)); |
| 221 | hints.ai_family = ai->ai_family; |
| 222 | hints.ai_socktype = ai->ai_socktype; |
| 223 | hints.ai_protocol = ai->ai_protocol; |
| 224 | hints.ai_flags = AI_PASSIVE; |
| 225 | gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); |
| 226 | if (gaierr) { |
| 227 | error("getaddrinfo: %s: %s", options.bind_address, |
| 228 | ssh_gai_strerror(gaierr)); |
| 229 | close(sock); |
| 230 | return -1; |
| 231 | } |
| 232 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { |
| 233 | error("bind: %s: %s", options.bind_address, strerror(errno)); |
| 234 | close(sock); |
| 235 | freeaddrinfo(res); |
| 236 | return -1; |
| 237 | } |
| 238 | freeaddrinfo(res); |
| 239 | return sock; |
| 240 | } |
| 241 | |
| 242 | static int |
| 243 | timeout_connect(int sockfd, const struct sockaddr *serv_addr, |
| 244 | socklen_t addrlen, int *timeoutp) |
| 245 | { |
| 246 | fd_set *fdset; |
| 247 | struct timeval tv, t_start; |
| 248 | socklen_t optlen; |
| 249 | int optval, rc, result = -1; |
| 250 | |
| 251 | gettimeofday(&t_start, NULL); |
| 252 | |
| 253 | if (*timeoutp <= 0) { |
| 254 | result = connect(sockfd, serv_addr, addrlen); |
| 255 | goto done; |
| 256 | } |
| 257 | |
| 258 | set_nonblock(sockfd); |
| 259 | rc = connect(sockfd, serv_addr, addrlen); |
| 260 | if (rc == 0) { |
| 261 | unset_nonblock(sockfd); |
| 262 | result = 0; |
| 263 | goto done; |
| 264 | } |
| 265 | if (errno != EINPROGRESS) { |
| 266 | result = -1; |
| 267 | goto done; |
| 268 | } |
| 269 | |
| 270 | fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), |
| 271 | sizeof(fd_mask)); |
| 272 | FD_SET(sockfd, fdset); |
| 273 | ms_to_timeval(&tv, *timeoutp); |
| 274 | |
| 275 | for (;;) { |
| 276 | rc = select(sockfd + 1, NULL, fdset, NULL, &tv); |
| 277 | if (rc != -1 || errno != EINTR) |
| 278 | break; |
| 279 | } |
| 280 | |
| 281 | switch (rc) { |
| 282 | case 0: |
| 283 | /* Timed out */ |
| 284 | errno = ETIMEDOUT; |
| 285 | break; |
| 286 | case -1: |
| 287 | /* Select error */ |
| 288 | debug("select: %s", strerror(errno)); |
| 289 | break; |
| 290 | case 1: |
| 291 | /* Completed or failed */ |
| 292 | optval = 0; |
| 293 | optlen = sizeof(optval); |
| 294 | if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, |
| 295 | &optlen) == -1) { |
| 296 | debug("getsockopt: %s", strerror(errno)); |
| 297 | break; |
| 298 | } |
| 299 | if (optval != 0) { |
| 300 | errno = optval; |
| 301 | break; |
| 302 | } |
| 303 | result = 0; |
| 304 | unset_nonblock(sockfd); |
| 305 | break; |
| 306 | default: |
| 307 | /* Should not occur */ |
| 308 | fatal("Bogus return (%d) from select()", rc); |
| 309 | } |
| 310 | |
| 311 | xfree(fdset); |
| 312 | |
| 313 | done: |
| 314 | if (result == 0 && *timeoutp > 0) { |
| 315 | ms_subtract_diff(&t_start, timeoutp); |
| 316 | if (*timeoutp <= 0) { |
| 317 | errno = ETIMEDOUT; |
| 318 | result = -1; |
| 319 | } |
| 320 | } |
| 321 | |
| 322 | return (result); |
| 323 | } |
| 324 | |
| 325 | /* |
| 326 | * Opens a TCP/IP connection to the remote server on the given host. |
| 327 | * The address of the remote host will be returned in hostaddr. |
| 328 | * If port is 0, the default port will be used. If needpriv is true, |
| 329 | * a privileged port will be allocated to make the connection. |
| 330 | * This requires super-user privileges if needpriv is true. |
| 331 | * Connection_attempts specifies the maximum number of tries (one per |
| 332 | * second). If proxy_command is non-NULL, it specifies the command (with %h |
| 333 | * and %p substituted for host and port, respectively) to use to contact |
| 334 | * the daemon. |
| 335 | */ |
| 336 | int |
| 337 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
| 338 | u_short port, int family, int connection_attempts, int *timeout_ms, |
| 339 | int want_keepalive, int needpriv, const char *proxy_command) |
| 340 | { |
| 341 | int gaierr; |
| 342 | int on = 1; |
| 343 | int sock = -1, attempt; |
| 344 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
| 345 | struct addrinfo hints, *ai, *aitop; |
| 346 | |
| 347 | debug2("ssh_connect: needpriv %d", needpriv); |
| 348 | |
| 349 | /* If a proxy command is given, connect using it. */ |
| 350 | if (proxy_command != NULL) |
| 351 | return ssh_proxy_connect(host, port, proxy_command); |
| 352 | |
| 353 | /* No proxy command. */ |
| 354 | |
| 355 | memset(&hints, 0, sizeof(hints)); |
| 356 | hints.ai_family = family; |
| 357 | hints.ai_socktype = SOCK_STREAM; |
| 358 | snprintf(strport, sizeof strport, "%u", port); |
| 359 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
| 360 | fatal("%s: Could not resolve hostname %.100s: %s", __progname, |
| 361 | host, ssh_gai_strerror(gaierr)); |
| 362 | |
| 363 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
| 364 | if (attempt > 0) { |
| 365 | /* Sleep a moment before retrying. */ |
| 366 | sleep(1); |
| 367 | debug("Trying again..."); |
| 368 | } |
| 369 | /* |
| 370 | * Loop through addresses for this host, and try each one in |
| 371 | * sequence until the connection succeeds. |
| 372 | */ |
| 373 | for (ai = aitop; ai; ai = ai->ai_next) { |
| 374 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) |
| 375 | continue; |
| 376 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, |
| 377 | ntop, sizeof(ntop), strport, sizeof(strport), |
| 378 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { |
| 379 | error("ssh_connect: getnameinfo failed"); |
| 380 | continue; |
| 381 | } |
| 382 | debug("Connecting to %.200s [%.100s] port %s.", |
| 383 | host, ntop, strport); |
| 384 | |
| 385 | /* Create a socket for connecting. */ |
| 386 | sock = ssh_create_socket(needpriv, ai); |
| 387 | if (sock < 0) |
| 388 | /* Any error is already output */ |
| 389 | continue; |
| 390 | |
| 391 | if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, |
| 392 | timeout_ms) >= 0) { |
| 393 | /* Successful connection. */ |
| 394 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
| 395 | break; |
| 396 | } else { |
| 397 | debug("connect to address %s port %s: %s", |
| 398 | ntop, strport, strerror(errno)); |
| 399 | close(sock); |
| 400 | sock = -1; |
| 401 | } |
| 402 | } |
| 403 | if (sock != -1) |
| 404 | break; /* Successful connection. */ |
| 405 | } |
| 406 | |
| 407 | freeaddrinfo(aitop); |
| 408 | |
| 409 | /* Return failure if we didn't get a successful connection. */ |
| 410 | if (sock == -1) { |
| 411 | error("ssh: connect to host %s port %s: %s", |
| 412 | host, strport, strerror(errno)); |
| 413 | return (-1); |
| 414 | } |
| 415 | |
| 416 | debug("Connection established."); |
| 417 | |
| 418 | /* Set SO_KEEPALIVE if requested. */ |
| 419 | if (want_keepalive && |
| 420 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, |
| 421 | sizeof(on)) < 0) |
| 422 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); |
| 423 | |
| 424 | /* Set the connection. */ |
| 425 | packet_set_connection(sock, sock); |
| 426 | packet_set_timeout(options.server_alive_interval, |
| 427 | options.server_alive_count_max); |
| 428 | |
| 429 | return 0; |
| 430 | } |
| 431 | |
| 432 | /* |
| 433 | * Waits for the server identification string, and sends our own |
| 434 | * identification string. |
| 435 | */ |
| 436 | void |
| 437 | ssh_exchange_identification(int timeout_ms) |
| 438 | { |
| 439 | char buf[256], remote_version[256]; /* must be same size! */ |
| 440 | int remote_major, remote_minor, mismatch; |
| 441 | int connection_in = packet_get_connection_in(); |
| 442 | int connection_out = packet_get_connection_out(); |
| 443 | int minor1 = PROTOCOL_MINOR_1; |
| 444 | u_int i, n; |
| 445 | size_t len; |
| 446 | int fdsetsz, remaining, rc; |
| 447 | struct timeval t_start, t_remaining; |
| 448 | fd_set *fdset; |
| 449 | |
| 450 | fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); |
| 451 | fdset = xcalloc(1, fdsetsz); |
| 452 | |
| 453 | /* Read other side's version identification. */ |
| 454 | remaining = timeout_ms; |
| 455 | for (n = 0;;) { |
| 456 | for (i = 0; i < sizeof(buf) - 1; i++) { |
| 457 | if (timeout_ms > 0) { |
| 458 | gettimeofday(&t_start, NULL); |
| 459 | ms_to_timeval(&t_remaining, remaining); |
| 460 | FD_SET(connection_in, fdset); |
| 461 | rc = select(connection_in + 1, fdset, NULL, |
| 462 | fdset, &t_remaining); |
| 463 | ms_subtract_diff(&t_start, &remaining); |
| 464 | if (rc == 0 || remaining <= 0) |
| 465 | fatal("Connection timed out during " |
| 466 | "banner exchange"); |
| 467 | if (rc == -1) { |
| 468 | if (errno == EINTR) |
| 469 | continue; |
| 470 | fatal("ssh_exchange_identification: " |
| 471 | "select: %s", strerror(errno)); |
| 472 | } |
| 473 | } |
| 474 | |
| 475 | len = roaming_atomicio(read, connection_in, &buf[i], 1); |
| 476 | |
| 477 | if (len != 1 && errno == EPIPE) |
| 478 | fatal("ssh_exchange_identification: " |
| 479 | "Connection closed by remote host"); |
| 480 | else if (len != 1) |
| 481 | fatal("ssh_exchange_identification: " |
| 482 | "read: %.100s", strerror(errno)); |
| 483 | if (buf[i] == '\r') { |
| 484 | buf[i] = '\n'; |
| 485 | buf[i + 1] = 0; |
| 486 | continue; /**XXX wait for \n */ |
| 487 | } |
| 488 | if (buf[i] == '\n') { |
| 489 | buf[i + 1] = 0; |
| 490 | break; |
| 491 | } |
| 492 | if (++n > 65536) |
| 493 | fatal("ssh_exchange_identification: " |
| 494 | "No banner received"); |
| 495 | } |
| 496 | buf[sizeof(buf) - 1] = 0; |
| 497 | if (strncmp(buf, "SSH-", 4) == 0) |
| 498 | break; |
| 499 | debug("ssh_exchange_identification: %s", buf); |
| 500 | } |
| 501 | server_version_string = xstrdup(buf); |
| 502 | xfree(fdset); |
| 503 | |
| 504 | /* |
| 505 | * Check that the versions match. In future this might accept |
| 506 | * several versions and set appropriate flags to handle them. |
| 507 | */ |
| 508 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
| 509 | &remote_major, &remote_minor, remote_version) != 3) |
| 510 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
| 511 | debug("Remote protocol version %d.%d, remote software version %.100s", |
| 512 | remote_major, remote_minor, remote_version); |
| 513 | |
| 514 | compat_datafellows(remote_version); |
| 515 | mismatch = 0; |
| 516 | |
| 517 | switch (remote_major) { |
| 518 | case 1: |
| 519 | if (remote_minor == 99 && |
| 520 | (options.protocol & SSH_PROTO_2) && |
| 521 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { |
| 522 | enable_compat20(); |
| 523 | break; |
| 524 | } |
| 525 | if (!(options.protocol & SSH_PROTO_1)) { |
| 526 | mismatch = 1; |
| 527 | break; |
| 528 | } |
| 529 | if (remote_minor < 3) { |
| 530 | fatal("Remote machine has too old SSH software version."); |
| 531 | } else if (remote_minor == 3 || remote_minor == 4) { |
| 532 | /* We speak 1.3, too. */ |
| 533 | enable_compat13(); |
| 534 | minor1 = 3; |
| 535 | if (options.forward_agent) { |
| 536 | logit("Agent forwarding disabled for protocol 1.3"); |
| 537 | options.forward_agent = 0; |
| 538 | } |
| 539 | } |
| 540 | break; |
| 541 | case 2: |
| 542 | if (options.protocol & SSH_PROTO_2) { |
| 543 | enable_compat20(); |
| 544 | break; |
| 545 | } |
| 546 | /* FALLTHROUGH */ |
| 547 | default: |
| 548 | mismatch = 1; |
| 549 | break; |
| 550 | } |
| 551 | if (mismatch) |
| 552 | fatal("Protocol major versions differ: %d vs. %d", |
| 553 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
| 554 | remote_major); |
| 555 | /* Send our own protocol version identification. */ |
| 556 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", |
| 557 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
| 558 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
| 559 | SSH_VERSION, compat20 ? "\r\n" : "\n"); |
| 560 | if (roaming_atomicio(vwrite, connection_out, buf, strlen(buf)) |
| 561 | != strlen(buf)) |
| 562 | fatal("write: %.100s", strerror(errno)); |
| 563 | client_version_string = xstrdup(buf); |
| 564 | chop(client_version_string); |
| 565 | chop(server_version_string); |
| 566 | debug("Local version string %.100s", client_version_string); |
| 567 | } |
| 568 | |
| 569 | /* defaults to 'no' */ |
| 570 | static int |
| 571 | confirm(const char *prompt) |
| 572 | { |
| 573 | const char *msg, *again = "Please type 'yes' or 'no': "; |
| 574 | char *p; |
| 575 | int ret = -1; |
| 576 | |
| 577 | if (options.batch_mode) |
| 578 | return 0; |
| 579 | for (msg = prompt;;msg = again) { |
| 580 | p = read_passphrase(msg, RP_ECHO); |
| 581 | if (p == NULL || |
| 582 | (p[0] == '\0') || (p[0] == '\n') || |
| 583 | strncasecmp(p, "no", 2) == 0) |
| 584 | ret = 0; |
| 585 | if (p && strncasecmp(p, "yes", 3) == 0) |
| 586 | ret = 1; |
| 587 | if (p) |
| 588 | xfree(p); |
| 589 | if (ret != -1) |
| 590 | return ret; |
| 591 | } |
| 592 | } |
| 593 | |
| 594 | static int |
| 595 | check_host_cert(const char *host, const Key *host_key) |
| 596 | { |
| 597 | const char *reason; |
| 598 | |
| 599 | if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) { |
| 600 | error("%s", reason); |
| 601 | return 0; |
| 602 | } |
| 603 | if (buffer_len(&host_key->cert->critical) != 0) { |
| 604 | error("Certificate for %s contains unsupported " |
| 605 | "critical options(s)", host); |
| 606 | return 0; |
| 607 | } |
| 608 | return 1; |
| 609 | } |
| 610 | |
| 611 | static int |
| 612 | sockaddr_is_local(struct sockaddr *hostaddr) |
| 613 | { |
| 614 | switch (hostaddr->sa_family) { |
| 615 | case AF_INET: |
| 616 | return (ntohl(((struct sockaddr_in *)hostaddr)-> |
| 617 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
| 618 | case AF_INET6: |
| 619 | return IN6_IS_ADDR_LOOPBACK( |
| 620 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); |
| 621 | default: |
| 622 | return 0; |
| 623 | } |
| 624 | } |
| 625 | |
| 626 | /* |
| 627 | * Prepare the hostname and ip address strings that are used to lookup |
| 628 | * host keys in known_hosts files. These may have a port number appended. |
| 629 | */ |
| 630 | void |
| 631 | get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, |
| 632 | u_short port, char **hostfile_hostname, char **hostfile_ipaddr) |
| 633 | { |
| 634 | char ntop[NI_MAXHOST]; |
| 635 | socklen_t addrlen; |
| 636 | |
| 637 | switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { |
| 638 | case -1: |
| 639 | addrlen = 0; |
| 640 | break; |
| 641 | case AF_INET: |
| 642 | addrlen = sizeof(struct sockaddr_in); |
| 643 | break; |
| 644 | case AF_INET6: |
| 645 | addrlen = sizeof(struct sockaddr_in6); |
| 646 | break; |
| 647 | default: |
| 648 | addrlen = sizeof(struct sockaddr); |
| 649 | break; |
| 650 | } |
| 651 | |
| 652 | /* |
| 653 | * We don't have the remote ip-address for connections |
| 654 | * using a proxy command |
| 655 | */ |
| 656 | if (hostfile_ipaddr != NULL) { |
| 657 | if (options.proxy_command == NULL) { |
| 658 | if (getnameinfo(hostaddr, addrlen, |
| 659 | ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) |
| 660 | fatal("check_host_key: getnameinfo failed"); |
| 661 | *hostfile_ipaddr = put_host_port(ntop, port); |
| 662 | } else { |
| 663 | *hostfile_ipaddr = xstrdup("<no hostip for proxy " |
| 664 | "command>"); |
| 665 | } |
| 666 | } |
| 667 | |
| 668 | /* |
| 669 | * Allow the user to record the key under a different name or |
| 670 | * differentiate a non-standard port. This is useful for ssh |
| 671 | * tunneling over forwarded connections or if you run multiple |
| 672 | * sshd's on different ports on the same machine. |
| 673 | */ |
| 674 | if (hostfile_hostname != NULL) { |
| 675 | if (options.host_key_alias != NULL) { |
| 676 | *hostfile_hostname = xstrdup(options.host_key_alias); |
| 677 | debug("using hostkeyalias: %s", *hostfile_hostname); |
| 678 | } else { |
| 679 | *hostfile_hostname = put_host_port(hostname, port); |
| 680 | } |
| 681 | } |
| 682 | } |
| 683 | |
| 684 | /* |
| 685 | * check whether the supplied host key is valid, return -1 if the key |
| 686 | * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. |
| 687 | */ |
| 688 | #define RDRW 0 |
| 689 | #define RDONLY 1 |
| 690 | #define ROQUIET 2 |
| 691 | static int |
| 692 | check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, |
| 693 | Key *host_key, int readonly, |
| 694 | char **user_hostfiles, u_int num_user_hostfiles, |
| 695 | char **system_hostfiles, u_int num_system_hostfiles) |
| 696 | { |
| 697 | HostStatus host_status; |
| 698 | HostStatus ip_status; |
| 699 | Key *raw_key = NULL; |
| 700 | char *ip = NULL, *host = NULL; |
| 701 | char hostline[1000], *hostp, *fp, *ra; |
| 702 | char msg[1024]; |
| 703 | const char *type; |
| 704 | const struct hostkey_entry *host_found, *ip_found; |
| 705 | int len, cancelled_forwarding = 0; |
| 706 | int local = sockaddr_is_local(hostaddr); |
| 707 | int r, want_cert = key_is_cert(host_key), host_ip_differ = 0; |
| 708 | struct hostkeys *host_hostkeys, *ip_hostkeys; |
| 709 | u_int i; |
| 710 | |
| 711 | /* |
| 712 | * Force accepting of the host key for loopback/localhost. The |
| 713 | * problem is that if the home directory is NFS-mounted to multiple |
| 714 | * machines, localhost will refer to a different machine in each of |
| 715 | * them, and the user will get bogus HOST_CHANGED warnings. This |
| 716 | * essentially disables host authentication for localhost; however, |
| 717 | * this is probably not a real problem. |
| 718 | */ |
| 719 | if (options.no_host_authentication_for_localhost == 1 && local && |
| 720 | options.host_key_alias == NULL) { |
| 721 | debug("Forcing accepting of host key for " |
| 722 | "loopback/localhost."); |
| 723 | return 0; |
| 724 | } |
| 725 | |
| 726 | /* |
| 727 | * Prepare the hostname and address strings used for hostkey lookup. |
| 728 | * In some cases, these will have a port number appended. |
| 729 | */ |
| 730 | get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); |
| 731 | |
| 732 | /* |
| 733 | * Turn off check_host_ip if the connection is to localhost, via proxy |
| 734 | * command or if we don't have a hostname to compare with |
| 735 | */ |
| 736 | if (options.check_host_ip && (local || |
| 737 | strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) |
| 738 | options.check_host_ip = 0; |
| 739 | |
| 740 | host_hostkeys = init_hostkeys(); |
| 741 | for (i = 0; i < num_user_hostfiles; i++) |
| 742 | load_hostkeys(host_hostkeys, host, user_hostfiles[i]); |
| 743 | for (i = 0; i < num_system_hostfiles; i++) |
| 744 | load_hostkeys(host_hostkeys, host, system_hostfiles[i]); |
| 745 | |
| 746 | ip_hostkeys = NULL; |
| 747 | if (!want_cert && options.check_host_ip) { |
| 748 | ip_hostkeys = init_hostkeys(); |
| 749 | for (i = 0; i < num_user_hostfiles; i++) |
| 750 | load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); |
| 751 | for (i = 0; i < num_system_hostfiles; i++) |
| 752 | load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); |
| 753 | } |
| 754 | |
| 755 | retry: |
| 756 | /* Reload these as they may have changed on cert->key downgrade */ |
| 757 | want_cert = key_is_cert(host_key); |
| 758 | type = key_type(host_key); |
| 759 | |
| 760 | /* |
| 761 | * Check if the host key is present in the user's list of known |
| 762 | * hosts or in the systemwide list. |
| 763 | */ |
| 764 | host_status = check_key_in_hostkeys(host_hostkeys, host_key, |
| 765 | &host_found); |
| 766 | |
| 767 | /* |
| 768 | * Also perform check for the ip address, skip the check if we are |
| 769 | * localhost, looking for a certificate, or the hostname was an ip |
| 770 | * address to begin with. |
| 771 | */ |
| 772 | if (!want_cert && ip_hostkeys != NULL) { |
| 773 | ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, |
| 774 | &ip_found); |
| 775 | if (host_status == HOST_CHANGED && |
| 776 | (ip_status != HOST_CHANGED || |
| 777 | (ip_found != NULL && |
| 778 | !key_equal(ip_found->key, host_found->key)))) |
| 779 | host_ip_differ = 1; |
| 780 | } else |
| 781 | ip_status = host_status; |
| 782 | |
| 783 | switch (host_status) { |
| 784 | case HOST_OK: |
| 785 | /* The host is known and the key matches. */ |
| 786 | debug("Host '%.200s' is known and matches the %s host %s.", |
| 787 | host, type, want_cert ? "certificate" : "key"); |
| 788 | debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", |
| 789 | host_found->file, host_found->line); |
| 790 | if (want_cert && !check_host_cert(hostname, host_key)) |
| 791 | goto fail; |
| 792 | if (options.check_host_ip && ip_status == HOST_NEW) { |
| 793 | if (readonly || want_cert) |
| 794 | logit("%s host key for IP address " |
| 795 | "'%.128s' not in list of known hosts.", |
| 796 | type, ip); |
| 797 | else if (!add_host_to_hostfile(user_hostfiles[0], ip, |
| 798 | host_key, options.hash_known_hosts)) |
| 799 | logit("Failed to add the %s host key for IP " |
| 800 | "address '%.128s' to the list of known " |
| 801 | "hosts (%.30s).", type, ip, |
| 802 | user_hostfiles[0]); |
| 803 | else |
| 804 | logit("Warning: Permanently added the %s host " |
| 805 | "key for IP address '%.128s' to the list " |
| 806 | "of known hosts.", type, ip); |
| 807 | } else if (options.visual_host_key) { |
| 808 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
| 809 | ra = key_fingerprint(host_key, SSH_FP_MD5, |
| 810 | SSH_FP_RANDOMART); |
| 811 | logit("Host key fingerprint is %s\n%s\n", fp, ra); |
| 812 | xfree(ra); |
| 813 | xfree(fp); |
| 814 | } |
| 815 | break; |
| 816 | case HOST_NEW: |
| 817 | if (options.host_key_alias == NULL && port != 0 && |
| 818 | port != SSH_DEFAULT_PORT) { |
| 819 | debug("checking without port identifier"); |
| 820 | if (check_host_key(hostname, hostaddr, 0, host_key, |
| 821 | ROQUIET, user_hostfiles, num_user_hostfiles, |
| 822 | system_hostfiles, num_system_hostfiles) == 0) { |
| 823 | debug("found matching key w/out port"); |
| 824 | break; |
| 825 | } |
| 826 | } |
| 827 | if (readonly || want_cert) |
| 828 | goto fail; |
| 829 | /* The host is new. */ |
| 830 | if (options.strict_host_key_checking == 1) { |
| 831 | /* |
| 832 | * User has requested strict host key checking. We |
| 833 | * will not add the host key automatically. The only |
| 834 | * alternative left is to abort. |
| 835 | */ |
| 836 | error("No %s host key is known for %.200s and you " |
| 837 | "have requested strict checking.", type, host); |
| 838 | goto fail; |
| 839 | } else if (options.strict_host_key_checking == 2) { |
| 840 | char msg1[1024], msg2[1024]; |
| 841 | |
| 842 | if (show_other_keys(host_hostkeys, host_key)) |
| 843 | snprintf(msg1, sizeof(msg1), |
| 844 | "\nbut keys of different type are already" |
| 845 | " known for this host."); |
| 846 | else |
| 847 | snprintf(msg1, sizeof(msg1), "."); |
| 848 | /* The default */ |
| 849 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
| 850 | ra = key_fingerprint(host_key, SSH_FP_MD5, |
| 851 | SSH_FP_RANDOMART); |
| 852 | msg2[0] = '\0'; |
| 853 | if (options.verify_host_key_dns) { |
| 854 | if (matching_host_key_dns) |
| 855 | snprintf(msg2, sizeof(msg2), |
| 856 | "Matching host key fingerprint" |
| 857 | " found in DNS.\n"); |
| 858 | else |
| 859 | snprintf(msg2, sizeof(msg2), |
| 860 | "No matching host key fingerprint" |
| 861 | " found in DNS.\n"); |
| 862 | } |
| 863 | snprintf(msg, sizeof(msg), |
| 864 | "The authenticity of host '%.200s (%s)' can't be " |
| 865 | "established%s\n" |
| 866 | "%s key fingerprint is %s.%s%s\n%s" |
| 867 | "Are you sure you want to continue connecting " |
| 868 | "(yes/no)? ", |
| 869 | host, ip, msg1, type, fp, |
| 870 | options.visual_host_key ? "\n" : "", |
| 871 | options.visual_host_key ? ra : "", |
| 872 | msg2); |
| 873 | xfree(ra); |
| 874 | xfree(fp); |
| 875 | if (!confirm(msg)) |
| 876 | goto fail; |
| 877 | } |
| 878 | /* |
| 879 | * If not in strict mode, add the key automatically to the |
| 880 | * local known_hosts file. |
| 881 | */ |
| 882 | if (options.check_host_ip && ip_status == HOST_NEW) { |
| 883 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
| 884 | hostp = hostline; |
| 885 | if (options.hash_known_hosts) { |
| 886 | /* Add hash of host and IP separately */ |
| 887 | r = add_host_to_hostfile(user_hostfiles[0], |
| 888 | host, host_key, options.hash_known_hosts) && |
| 889 | add_host_to_hostfile(user_hostfiles[0], ip, |
| 890 | host_key, options.hash_known_hosts); |
| 891 | } else { |
| 892 | /* Add unhashed "host,ip" */ |
| 893 | r = add_host_to_hostfile(user_hostfiles[0], |
| 894 | hostline, host_key, |
| 895 | options.hash_known_hosts); |
| 896 | } |
| 897 | } else { |
| 898 | r = add_host_to_hostfile(user_hostfiles[0], host, |
| 899 | host_key, options.hash_known_hosts); |
| 900 | hostp = host; |
| 901 | } |
| 902 | |
| 903 | if (!r) |
| 904 | logit("Failed to add the host to the list of known " |
| 905 | "hosts (%.500s).", user_hostfiles[0]); |
| 906 | else |
| 907 | logit("Warning: Permanently added '%.200s' (%s) to the " |
| 908 | "list of known hosts.", hostp, type); |
| 909 | break; |
| 910 | case HOST_REVOKED: |
| 911 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 912 | error("@ WARNING: REVOKED HOST KEY DETECTED! @"); |
| 913 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 914 | error("The %s host key for %s is marked as revoked.", type, host); |
| 915 | error("This could mean that a stolen key is being used to"); |
| 916 | error("impersonate this host."); |
| 917 | |
| 918 | /* |
| 919 | * If strict host key checking is in use, the user will have |
| 920 | * to edit the key manually and we can only abort. |
| 921 | */ |
| 922 | if (options.strict_host_key_checking) { |
| 923 | error("%s host key for %.200s was revoked and you have " |
| 924 | "requested strict checking.", type, host); |
| 925 | goto fail; |
| 926 | } |
| 927 | goto continue_unsafe; |
| 928 | |
| 929 | case HOST_CHANGED: |
| 930 | if (want_cert) { |
| 931 | /* |
| 932 | * This is only a debug() since it is valid to have |
| 933 | * CAs with wildcard DNS matches that don't match |
| 934 | * all hosts that one might visit. |
| 935 | */ |
| 936 | debug("Host certificate authority does not " |
| 937 | "match %s in %s:%lu", CA_MARKER, |
| 938 | host_found->file, host_found->line); |
| 939 | goto fail; |
| 940 | } |
| 941 | if (readonly == ROQUIET) |
| 942 | goto fail; |
| 943 | if (options.check_host_ip && host_ip_differ) { |
| 944 | char *key_msg; |
| 945 | if (ip_status == HOST_NEW) |
| 946 | key_msg = "is unknown"; |
| 947 | else if (ip_status == HOST_OK) |
| 948 | key_msg = "is unchanged"; |
| 949 | else |
| 950 | key_msg = "has a different value"; |
| 951 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 952 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); |
| 953 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 954 | error("The %s host key for %s has changed,", type, host); |
| 955 | error("and the key for the corresponding IP address %s", ip); |
| 956 | error("%s. This could either mean that", key_msg); |
| 957 | error("DNS SPOOFING is happening or the IP address for the host"); |
| 958 | error("and its host key have changed at the same time."); |
| 959 | if (ip_status != HOST_NEW) |
| 960 | error("Offending key for IP in %s:%lu", |
| 961 | ip_found->file, ip_found->line); |
| 962 | } |
| 963 | /* The host key has changed. */ |
| 964 | warn_changed_key(host_key); |
| 965 | error("Add correct host key in %.100s to get rid of this message.", |
| 966 | user_hostfiles[0]); |
| 967 | error("Offending %s key in %s:%lu", key_type(host_found->key), |
| 968 | host_found->file, host_found->line); |
| 969 | |
| 970 | /* |
| 971 | * If strict host key checking is in use, the user will have |
| 972 | * to edit the key manually and we can only abort. |
| 973 | */ |
| 974 | if (options.strict_host_key_checking) { |
| 975 | error("%s host key for %.200s has changed and you have " |
| 976 | "requested strict checking.", type, host); |
| 977 | goto fail; |
| 978 | } |
| 979 | |
| 980 | continue_unsafe: |
| 981 | /* |
| 982 | * If strict host key checking has not been requested, allow |
| 983 | * the connection but without MITM-able authentication or |
| 984 | * forwarding. |
| 985 | */ |
| 986 | if (options.password_authentication) { |
| 987 | error("Password authentication is disabled to avoid " |
| 988 | "man-in-the-middle attacks."); |
| 989 | options.password_authentication = 0; |
| 990 | cancelled_forwarding = 1; |
| 991 | } |
| 992 | if (options.kbd_interactive_authentication) { |
| 993 | error("Keyboard-interactive authentication is disabled" |
| 994 | " to avoid man-in-the-middle attacks."); |
| 995 | options.kbd_interactive_authentication = 0; |
| 996 | options.challenge_response_authentication = 0; |
| 997 | cancelled_forwarding = 1; |
| 998 | } |
| 999 | if (options.challenge_response_authentication) { |
| 1000 | error("Challenge/response authentication is disabled" |
| 1001 | " to avoid man-in-the-middle attacks."); |
| 1002 | options.challenge_response_authentication = 0; |
| 1003 | cancelled_forwarding = 1; |
| 1004 | } |
| 1005 | if (options.forward_agent) { |
| 1006 | error("Agent forwarding is disabled to avoid " |
| 1007 | "man-in-the-middle attacks."); |
| 1008 | options.forward_agent = 0; |
| 1009 | cancelled_forwarding = 1; |
| 1010 | } |
| 1011 | if (options.forward_x11) { |
| 1012 | error("X11 forwarding is disabled to avoid " |
| 1013 | "man-in-the-middle attacks."); |
| 1014 | options.forward_x11 = 0; |
| 1015 | cancelled_forwarding = 1; |
| 1016 | } |
| 1017 | if (options.num_local_forwards > 0 || |
| 1018 | options.num_remote_forwards > 0) { |
| 1019 | error("Port forwarding is disabled to avoid " |
| 1020 | "man-in-the-middle attacks."); |
| 1021 | options.num_local_forwards = |
| 1022 | options.num_remote_forwards = 0; |
| 1023 | cancelled_forwarding = 1; |
| 1024 | } |
| 1025 | if (options.tun_open != SSH_TUNMODE_NO) { |
| 1026 | error("Tunnel forwarding is disabled to avoid " |
| 1027 | "man-in-the-middle attacks."); |
| 1028 | options.tun_open = SSH_TUNMODE_NO; |
| 1029 | cancelled_forwarding = 1; |
| 1030 | } |
| 1031 | if (options.exit_on_forward_failure && cancelled_forwarding) |
| 1032 | fatal("Error: forwarding disabled due to host key " |
| 1033 | "check failure"); |
| 1034 | |
| 1035 | /* |
| 1036 | * XXX Should permit the user to change to use the new id. |
| 1037 | * This could be done by converting the host key to an |
| 1038 | * identifying sentence, tell that the host identifies itself |
| 1039 | * by that sentence, and ask the user if he/she wishes to |
| 1040 | * accept the authentication. |
| 1041 | */ |
| 1042 | break; |
| 1043 | case HOST_FOUND: |
| 1044 | fatal("internal error"); |
| 1045 | break; |
| 1046 | } |
| 1047 | |
| 1048 | if (options.check_host_ip && host_status != HOST_CHANGED && |
| 1049 | ip_status == HOST_CHANGED) { |
| 1050 | snprintf(msg, sizeof(msg), |
| 1051 | "Warning: the %s host key for '%.200s' " |
| 1052 | "differs from the key for the IP address '%.128s'" |
| 1053 | "\nOffending key for IP in %s:%lu", |
| 1054 | type, host, ip, ip_found->file, ip_found->line); |
| 1055 | if (host_status == HOST_OK) { |
| 1056 | len = strlen(msg); |
| 1057 | snprintf(msg + len, sizeof(msg) - len, |
| 1058 | "\nMatching host key in %s:%lu", |
| 1059 | host_found->file, host_found->line); |
| 1060 | } |
| 1061 | if (options.strict_host_key_checking == 1) { |
| 1062 | logit("%s", msg); |
| 1063 | error("Exiting, you have requested strict checking."); |
| 1064 | goto fail; |
| 1065 | } else if (options.strict_host_key_checking == 2) { |
| 1066 | strlcat(msg, "\nAre you sure you want " |
| 1067 | "to continue connecting (yes/no)? ", sizeof(msg)); |
| 1068 | if (!confirm(msg)) |
| 1069 | goto fail; |
| 1070 | } else { |
| 1071 | logit("%s", msg); |
| 1072 | } |
| 1073 | } |
| 1074 | |
| 1075 | xfree(ip); |
| 1076 | xfree(host); |
| 1077 | if (host_hostkeys != NULL) |
| 1078 | free_hostkeys(host_hostkeys); |
| 1079 | if (ip_hostkeys != NULL) |
| 1080 | free_hostkeys(ip_hostkeys); |
| 1081 | return 0; |
| 1082 | |
| 1083 | fail: |
| 1084 | if (want_cert && host_status != HOST_REVOKED) { |
| 1085 | /* |
| 1086 | * No matching certificate. Downgrade cert to raw key and |
| 1087 | * search normally. |
| 1088 | */ |
| 1089 | debug("No matching CA found. Retry with plain key"); |
| 1090 | raw_key = key_from_private(host_key); |
| 1091 | if (key_drop_cert(raw_key) != 0) |
| 1092 | fatal("Couldn't drop certificate"); |
| 1093 | host_key = raw_key; |
| 1094 | goto retry; |
| 1095 | } |
| 1096 | if (raw_key != NULL) |
| 1097 | key_free(raw_key); |
| 1098 | xfree(ip); |
| 1099 | xfree(host); |
| 1100 | if (host_hostkeys != NULL) |
| 1101 | free_hostkeys(host_hostkeys); |
| 1102 | if (ip_hostkeys != NULL) |
| 1103 | free_hostkeys(ip_hostkeys); |
| 1104 | return -1; |
| 1105 | } |
| 1106 | |
| 1107 | /* returns 0 if key verifies or -1 if key does NOT verify */ |
| 1108 | int |
| 1109 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) |
| 1110 | { |
| 1111 | int flags = 0; |
| 1112 | char *fp; |
| 1113 | |
| 1114 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
| 1115 | debug("Server host key: %s %s", key_type(host_key), fp); |
| 1116 | xfree(fp); |
| 1117 | |
| 1118 | /* XXX certs are not yet supported for DNS */ |
| 1119 | if (!key_is_cert(host_key) && options.verify_host_key_dns && |
| 1120 | verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) { |
| 1121 | if (flags & DNS_VERIFY_FOUND) { |
| 1122 | |
| 1123 | if (options.verify_host_key_dns == 1 && |
| 1124 | flags & DNS_VERIFY_MATCH && |
| 1125 | flags & DNS_VERIFY_SECURE) |
| 1126 | return 0; |
| 1127 | |
| 1128 | if (flags & DNS_VERIFY_MATCH) { |
| 1129 | matching_host_key_dns = 1; |
| 1130 | } else { |
| 1131 | warn_changed_key(host_key); |
| 1132 | error("Update the SSHFP RR in DNS with the new " |
| 1133 | "host key to get rid of this message."); |
| 1134 | } |
| 1135 | } |
| 1136 | } |
| 1137 | |
| 1138 | return check_host_key(host, hostaddr, options.port, host_key, RDRW, |
| 1139 | options.user_hostfiles, options.num_user_hostfiles, |
| 1140 | options.system_hostfiles, options.num_system_hostfiles); |
| 1141 | } |
| 1142 | |
| 1143 | /* |
| 1144 | * Starts a dialog with the server, and authenticates the current user on the |
| 1145 | * server. This does not need any extra privileges. The basic connection |
| 1146 | * to the server must already have been established before this is called. |
| 1147 | * If login fails, this function prints an error and never returns. |
| 1148 | * This function does not require super-user privileges. |
| 1149 | */ |
| 1150 | void |
| 1151 | ssh_login(Sensitive *sensitive, const char *orighost, |
| 1152 | struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) |
| 1153 | { |
| 1154 | char *host, *cp; |
| 1155 | char *server_user, *local_user; |
| 1156 | |
| 1157 | local_user = xstrdup(pw->pw_name); |
| 1158 | server_user = options.user ? options.user : local_user; |
| 1159 | |
| 1160 | /* Convert the user-supplied hostname into all lowercase. */ |
| 1161 | host = xstrdup(orighost); |
| 1162 | for (cp = host; *cp; cp++) |
| 1163 | if (isupper(*cp)) |
| 1164 | *cp = (char)tolower(*cp); |
| 1165 | |
| 1166 | /* Exchange protocol version identification strings with the server. */ |
| 1167 | ssh_exchange_identification(timeout_ms); |
| 1168 | |
| 1169 | /* Put the connection into non-blocking mode. */ |
| 1170 | packet_set_nonblocking(); |
| 1171 | |
| 1172 | /* key exchange */ |
| 1173 | /* authenticate user */ |
| 1174 | if (compat20) { |
| 1175 | ssh_kex2(host, hostaddr, port); |
| 1176 | ssh_userauth2(local_user, server_user, host, sensitive); |
| 1177 | } else { |
| 1178 | ssh_kex(host, hostaddr); |
| 1179 | ssh_userauth1(local_user, server_user, host, sensitive); |
| 1180 | } |
| 1181 | xfree(local_user); |
| 1182 | } |
| 1183 | |
| 1184 | void |
| 1185 | ssh_put_password(char *password) |
| 1186 | { |
| 1187 | int size; |
| 1188 | char *padded; |
| 1189 | |
| 1190 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
| 1191 | packet_put_cstring(password); |
| 1192 | return; |
| 1193 | } |
| 1194 | size = roundup(strlen(password) + 1, 32); |
| 1195 | padded = xcalloc(1, size); |
| 1196 | strlcpy(padded, password, size); |
| 1197 | packet_put_string(padded, size); |
| 1198 | memset(padded, 0, size); |
| 1199 | xfree(padded); |
| 1200 | } |
| 1201 | |
| 1202 | /* print all known host keys for a given host, but skip keys of given type */ |
| 1203 | static int |
| 1204 | show_other_keys(struct hostkeys *hostkeys, Key *key) |
| 1205 | { |
| 1206 | int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, KEY_ECDSA, -1}; |
| 1207 | int i, ret = 0; |
| 1208 | char *fp, *ra; |
| 1209 | const struct hostkey_entry *found; |
| 1210 | |
| 1211 | for (i = 0; type[i] != -1; i++) { |
| 1212 | if (type[i] == key->type) |
| 1213 | continue; |
| 1214 | if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) |
| 1215 | continue; |
| 1216 | fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX); |
| 1217 | ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART); |
| 1218 | logit("WARNING: %s key found for host %s\n" |
| 1219 | "in %s:%lu\n" |
| 1220 | "%s key fingerprint %s.", |
| 1221 | key_type(found->key), |
| 1222 | found->host, found->file, found->line, |
| 1223 | key_type(found->key), fp); |
| 1224 | if (options.visual_host_key) |
| 1225 | logit("%s", ra); |
| 1226 | xfree(ra); |
| 1227 | xfree(fp); |
| 1228 | ret = 1; |
| 1229 | } |
| 1230 | return ret; |
| 1231 | } |
| 1232 | |
| 1233 | static void |
| 1234 | warn_changed_key(Key *host_key) |
| 1235 | { |
| 1236 | char *fp; |
| 1237 | |
| 1238 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
| 1239 | |
| 1240 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 1241 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
| 1242 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 1243 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); |
| 1244 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); |
| 1245 | error("It is also possible that a host key has just been changed."); |
| 1246 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
| 1247 | key_type(host_key), fp); |
| 1248 | error("Please contact your system administrator."); |
| 1249 | |
| 1250 | xfree(fp); |
| 1251 | } |
| 1252 | |
| 1253 | /* |
| 1254 | * Execute a local command |
| 1255 | */ |
| 1256 | int |
| 1257 | ssh_local_cmd(const char *args) |
| 1258 | { |
| 1259 | char *shell; |
| 1260 | pid_t pid; |
| 1261 | int status; |
| 1262 | void (*osighand)(int); |
| 1263 | |
| 1264 | if (!options.permit_local_command || |
| 1265 | args == NULL || !*args) |
| 1266 | return (1); |
| 1267 | |
| 1268 | if ((shell = getenv("SHELL")) == NULL || *shell == '\0') |
| 1269 | shell = _PATH_BSHELL; |
| 1270 | |
| 1271 | osighand = signal(SIGCHLD, SIG_DFL); |
| 1272 | pid = fork(); |
| 1273 | if (pid == 0) { |
| 1274 | signal(SIGPIPE, SIG_DFL); |
| 1275 | debug3("Executing %s -c \"%s\"", shell, args); |
| 1276 | execl(shell, shell, "-c", args, (char *)NULL); |
| 1277 | error("Couldn't execute %s -c \"%s\": %s", |
| 1278 | shell, args, strerror(errno)); |
| 1279 | _exit(1); |
| 1280 | } else if (pid == -1) |
| 1281 | fatal("fork failed: %.100s", strerror(errno)); |
| 1282 | while (waitpid(pid, &status, 0) == -1) |
| 1283 | if (errno != EINTR) |
| 1284 | fatal("Couldn't wait for child: %s", strerror(errno)); |
| 1285 | signal(SIGCHLD, osighand); |
| 1286 | |
| 1287 | if (!WIFEXITED(status)) |
| 1288 | return (1); |
| 1289 | |
| 1290 | return (WEXITSTATUS(status)); |
| 1291 | } |