1 /* $OpenBSD: sshconnect.c,v 1.314 2019/02/27 19:37:01 markus Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * Code to connect to a remote host, and to perform the client side of the 7 * login (authentication) dialog. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 */ 15 16 #include "includes.h" 17 18 #include <sys/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 <net/if.h> 27 #include <netinet/in.h> 28 #include <arpa/inet.h> 29 30 #include <ctype.h> 31 #include <errno.h> 32 #include <fcntl.h> 33 #include <netdb.h> 34 #ifdef HAVE_PATHS_H 35 #include <paths.h> 36 #endif 37 #include <pwd.h> 38 #ifdef HAVE_POLL_H 39 #include <poll.h> 40 #endif 41 #include <signal.h> 42 #include <stdarg.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 #ifdef HAVE_IFADDRS_H 48 # include <ifaddrs.h> 49 #endif 50 51 #include "xmalloc.h" 52 #include "hostfile.h" 53 #include "ssh.h" 54 #include "sshbuf.h" 55 #include "packet.h" 56 #include "compat.h" 57 #include "sshkey.h" 58 #include "sshconnect.h" 59 #include "hostfile.h" 60 #include "log.h" 61 #include "misc.h" 62 #include "readconf.h" 63 #include "atomicio.h" 64 #include "dns.h" 65 #include "monitor_fdpass.h" 66 #include "ssh2.h" 67 #include "version.h" 68 #include "authfile.h" 69 #include "ssherr.h" 70 #include "authfd.h" 71 #include "kex.h" 72 73 struct sshkey *previous_host_key = NULL; 74 75 static int matching_host_key_dns = 0; 76 77 static pid_t proxy_command_pid = 0; 78 79 /* import */ 80 extern int debug_flag; 81 extern Options options; 82 extern char *__progname; 83 84 static int show_other_keys(struct hostkeys *, struct sshkey *); 85 static void warn_changed_key(struct sshkey *); 86 87 /* Expand a proxy command */ 88 static char * 89 expand_proxy_command(const char *proxy_command, const char *user, 90 const char *host, int port) 91 { 92 char *tmp, *ret, strport[NI_MAXSERV]; 93 94 snprintf(strport, sizeof strport, "%d", port); 95 xasprintf(&tmp, "exec %s", proxy_command); 96 ret = percent_expand(tmp, "h", host, "p", strport, 97 "r", options.user, (char *)NULL); 98 free(tmp); 99 return ret; 100 } 101 102 static void 103 stderr_null(void) 104 { 105 int devnull; 106 107 if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) { 108 error("Can't open %s for stderr redirection: %s", 109 _PATH_DEVNULL, strerror(errno)); 110 return; 111 } 112 if (devnull == STDERR_FILENO) 113 return; 114 if (dup2(devnull, STDERR_FILENO) == -1) 115 error("Cannot redirect stderr to %s", _PATH_DEVNULL); 116 if (devnull > STDERR_FILENO) 117 close(devnull); 118 } 119 120 /* 121 * Connect to the given ssh server using a proxy command that passes a 122 * a connected fd back to us. 123 */ 124 static int 125 ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port, 126 const char *proxy_command) 127 { 128 char *command_string; 129 int sp[2], sock; 130 pid_t pid; 131 char *shell; 132 133 if ((shell = getenv("SHELL")) == NULL) 134 shell = _PATH_BSHELL; 135 136 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 137 fatal("Could not create socketpair to communicate with " 138 "proxy dialer: %.100s", strerror(errno)); 139 140 command_string = expand_proxy_command(proxy_command, options.user, 141 host, port); 142 debug("Executing proxy dialer command: %.500s", command_string); 143 144 /* Fork and execute the proxy command. */ 145 if ((pid = fork()) == 0) { 146 char *argv[10]; 147 148 close(sp[1]); 149 /* Redirect stdin and stdout. */ 150 if (sp[0] != 0) { 151 if (dup2(sp[0], 0) < 0) 152 perror("dup2 stdin"); 153 } 154 if (sp[0] != 1) { 155 if (dup2(sp[0], 1) < 0) 156 perror("dup2 stdout"); 157 } 158 if (sp[0] >= 2) 159 close(sp[0]); 160 161 /* 162 * Stderr is left for non-ControlPersist connections is so 163 * error messages may be printed on the user's terminal. 164 */ 165 if (!debug_flag && options.control_path != NULL && 166 options.control_persist) 167 stderr_null(); 168 169 argv[0] = shell; 170 argv[1] = "-c"; 171 argv[2] = command_string; 172 argv[3] = NULL; 173 174 /* 175 * Execute the proxy command. 176 * Note that we gave up any extra privileges above. 177 */ 178 execv(argv[0], argv); 179 perror(argv[0]); 180 exit(1); 181 } 182 /* Parent. */ 183 if (pid < 0) 184 fatal("fork failed: %.100s", strerror(errno)); 185 close(sp[0]); 186 free(command_string); 187 188 if ((sock = mm_receive_fd(sp[1])) == -1) 189 fatal("proxy dialer did not pass back a connection"); 190 close(sp[1]); 191 192 while (waitpid(pid, NULL, 0) == -1) 193 if (errno != EINTR) 194 fatal("Couldn't wait for child: %s", strerror(errno)); 195 196 /* Set the connection file descriptors. */ 197 if (ssh_packet_set_connection(ssh, sock, sock) == NULL) 198 return -1; /* ssh_packet_set_connection logs error */ 199 200 return 0; 201 } 202 203 /* 204 * Connect to the given ssh server using a proxy command. 205 */ 206 static int 207 ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port, 208 const char *proxy_command) 209 { 210 char *command_string; 211 int pin[2], pout[2]; 212 pid_t pid; 213 char *shell; 214 215 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 216 shell = _PATH_BSHELL; 217 218 /* Create pipes for communicating with the proxy. */ 219 if (pipe(pin) < 0 || pipe(pout) < 0) 220 fatal("Could not create pipes to communicate with the proxy: %.100s", 221 strerror(errno)); 222 223 command_string = expand_proxy_command(proxy_command, options.user, 224 host, port); 225 debug("Executing proxy command: %.500s", command_string); 226 227 /* Fork and execute the proxy command. */ 228 if ((pid = fork()) == 0) { 229 char *argv[10]; 230 231 /* Redirect stdin and stdout. */ 232 close(pin[1]); 233 if (pin[0] != 0) { 234 if (dup2(pin[0], 0) < 0) 235 perror("dup2 stdin"); 236 close(pin[0]); 237 } 238 close(pout[0]); 239 if (dup2(pout[1], 1) < 0) 240 perror("dup2 stdout"); 241 /* Cannot be 1 because pin allocated two descriptors. */ 242 close(pout[1]); 243 244 /* 245 * Stderr is left for non-ControlPersist connections is so 246 * error messages may be printed on the user's terminal. 247 */ 248 if (!debug_flag && options.control_path != NULL && 249 options.control_persist) 250 stderr_null(); 251 252 argv[0] = shell; 253 argv[1] = "-c"; 254 argv[2] = command_string; 255 argv[3] = NULL; 256 257 /* Execute the proxy command. Note that we gave up any 258 extra privileges above. */ 259 signal(SIGPIPE, SIG_DFL); 260 execv(argv[0], argv); 261 perror(argv[0]); 262 exit(1); 263 } 264 /* Parent. */ 265 if (pid < 0) 266 fatal("fork failed: %.100s", strerror(errno)); 267 else 268 proxy_command_pid = pid; /* save pid to clean up later */ 269 270 /* Close child side of the descriptors. */ 271 close(pin[0]); 272 close(pout[1]); 273 274 /* Free the command name. */ 275 free(command_string); 276 277 /* Set the connection file descriptors. */ 278 if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL) 279 return -1; /* ssh_packet_set_connection logs error */ 280 281 return 0; 282 } 283 284 void 285 ssh_kill_proxy_command(void) 286 { 287 /* 288 * Send SIGHUP to proxy command if used. We don't wait() in 289 * case it hangs and instead rely on init to reap the child 290 */ 291 if (proxy_command_pid > 1) 292 kill(proxy_command_pid, SIGHUP); 293 } 294 295 #ifdef HAVE_IFADDRS_H 296 /* 297 * Search a interface address list (returned from getifaddrs(3)) for an 298 * address that matches the desired address family on the specified interface. 299 * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure. 300 */ 301 static int 302 check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs, 303 struct sockaddr_storage *resultp, socklen_t *rlenp) 304 { 305 struct sockaddr_in6 *sa6; 306 struct sockaddr_in *sa; 307 struct in6_addr *v6addr; 308 const struct ifaddrs *ifa; 309 int allow_local; 310 311 /* 312 * Prefer addresses that are not loopback or linklocal, but use them 313 * if nothing else matches. 314 */ 315 for (allow_local = 0; allow_local < 2; allow_local++) { 316 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 317 if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL || 318 (ifa->ifa_flags & IFF_UP) == 0 || 319 ifa->ifa_addr->sa_family != af || 320 strcmp(ifa->ifa_name, options.bind_interface) != 0) 321 continue; 322 switch (ifa->ifa_addr->sa_family) { 323 case AF_INET: 324 sa = (struct sockaddr_in *)ifa->ifa_addr; 325 if (!allow_local && sa->sin_addr.s_addr == 326 htonl(INADDR_LOOPBACK)) 327 continue; 328 if (*rlenp < sizeof(struct sockaddr_in)) { 329 error("%s: v4 addr doesn't fit", 330 __func__); 331 return -1; 332 } 333 *rlenp = sizeof(struct sockaddr_in); 334 memcpy(resultp, sa, *rlenp); 335 return 0; 336 case AF_INET6: 337 sa6 = (struct sockaddr_in6 *)ifa->ifa_addr; 338 v6addr = &sa6->sin6_addr; 339 if (!allow_local && 340 (IN6_IS_ADDR_LINKLOCAL(v6addr) || 341 IN6_IS_ADDR_LOOPBACK(v6addr))) 342 continue; 343 if (*rlenp < sizeof(struct sockaddr_in6)) { 344 error("%s: v6 addr doesn't fit", 345 __func__); 346 return -1; 347 } 348 *rlenp = sizeof(struct sockaddr_in6); 349 memcpy(resultp, sa6, *rlenp); 350 return 0; 351 } 352 } 353 } 354 return -1; 355 } 356 #endif 357 358 /* 359 * Creates a socket for use as the ssh connection. 360 */ 361 static int 362 ssh_create_socket(struct addrinfo *ai) 363 { 364 int sock, r; 365 struct sockaddr_storage bindaddr; 366 socklen_t bindaddrlen = 0; 367 struct addrinfo hints, *res = NULL; 368 #ifdef HAVE_IFADDRS_H 369 struct ifaddrs *ifaddrs = NULL; 370 #endif 371 char ntop[NI_MAXHOST]; 372 373 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 374 if (sock < 0) { 375 error("socket: %s", strerror(errno)); 376 return -1; 377 } 378 fcntl(sock, F_SETFD, FD_CLOEXEC); 379 380 /* Bind the socket to an alternative local IP address */ 381 if (options.bind_address == NULL && options.bind_interface == NULL) 382 return sock; 383 384 if (options.bind_address != NULL) { 385 memset(&hints, 0, sizeof(hints)); 386 hints.ai_family = ai->ai_family; 387 hints.ai_socktype = ai->ai_socktype; 388 hints.ai_protocol = ai->ai_protocol; 389 hints.ai_flags = AI_PASSIVE; 390 if ((r = getaddrinfo(options.bind_address, NULL, 391 &hints, &res)) != 0) { 392 error("getaddrinfo: %s: %s", options.bind_address, 393 ssh_gai_strerror(r)); 394 goto fail; 395 } 396 if (res == NULL) { 397 error("getaddrinfo: no addrs"); 398 goto fail; 399 } 400 memcpy(&bindaddr, res->ai_addr, res->ai_addrlen); 401 bindaddrlen = res->ai_addrlen; 402 } else if (options.bind_interface != NULL) { 403 #ifdef HAVE_IFADDRS_H 404 if ((r = getifaddrs(&ifaddrs)) != 0) { 405 error("getifaddrs: %s: %s", options.bind_interface, 406 strerror(errno)); 407 goto fail; 408 } 409 bindaddrlen = sizeof(bindaddr); 410 if (check_ifaddrs(options.bind_interface, ai->ai_family, 411 ifaddrs, &bindaddr, &bindaddrlen) != 0) { 412 logit("getifaddrs: %s: no suitable addresses", 413 options.bind_interface); 414 goto fail; 415 } 416 #else 417 error("BindInterface not supported on this platform."); 418 #endif 419 } 420 if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen, 421 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) { 422 error("%s: getnameinfo failed: %s", __func__, 423 ssh_gai_strerror(r)); 424 goto fail; 425 } 426 if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) { 427 error("bind %s: %s", ntop, strerror(errno)); 428 goto fail; 429 } 430 debug("%s: bound to %s", __func__, ntop); 431 /* success */ 432 goto out; 433 fail: 434 close(sock); 435 sock = -1; 436 out: 437 if (res != NULL) 438 freeaddrinfo(res); 439 #ifdef HAVE_IFADDRS_H 440 if (ifaddrs != NULL) 441 freeifaddrs(ifaddrs); 442 #endif 443 return sock; 444 } 445 446 /* 447 * Opens a TCP/IP connection to the remote server on the given host. 448 * The address of the remote host will be returned in hostaddr. 449 * If port is 0, the default port will be used. 450 * Connection_attempts specifies the maximum number of tries (one per 451 * second). If proxy_command is non-NULL, it specifies the command (with %h 452 * and %p substituted for host and port, respectively) to use to contact 453 * the daemon. 454 */ 455 static int 456 ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop, 457 struct sockaddr_storage *hostaddr, u_short port, int family, 458 int connection_attempts, int *timeout_ms, int want_keepalive) 459 { 460 int on = 1, saved_timeout_ms = *timeout_ms; 461 int oerrno, sock = -1, attempt; 462 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 463 struct addrinfo *ai; 464 465 debug2("%s", __func__); 466 memset(ntop, 0, sizeof(ntop)); 467 memset(strport, 0, sizeof(strport)); 468 469 for (attempt = 0; attempt < connection_attempts; attempt++) { 470 if (attempt > 0) { 471 /* Sleep a moment before retrying. */ 472 sleep(1); 473 debug("Trying again..."); 474 } 475 /* 476 * Loop through addresses for this host, and try each one in 477 * sequence until the connection succeeds. 478 */ 479 for (ai = aitop; ai; ai = ai->ai_next) { 480 if (ai->ai_family != AF_INET && 481 ai->ai_family != AF_INET6) { 482 errno = EAFNOSUPPORT; 483 continue; 484 } 485 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 486 ntop, sizeof(ntop), strport, sizeof(strport), 487 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 488 oerrno = errno; 489 error("%s: getnameinfo failed", __func__); 490 errno = oerrno; 491 continue; 492 } 493 debug("Connecting to %.200s [%.100s] port %s.", 494 host, ntop, strport); 495 496 /* Create a socket for connecting. */ 497 sock = ssh_create_socket(ai); 498 if (sock < 0) { 499 /* Any error is already output */ 500 errno = 0; 501 continue; 502 } 503 504 *timeout_ms = saved_timeout_ms; 505 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 506 timeout_ms) >= 0) { 507 /* Successful connection. */ 508 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 509 break; 510 } else { 511 oerrno = errno; 512 debug("connect to address %s port %s: %s", 513 ntop, strport, strerror(errno)); 514 close(sock); 515 sock = -1; 516 errno = oerrno; 517 } 518 } 519 if (sock != -1) 520 break; /* Successful connection. */ 521 } 522 523 /* Return failure if we didn't get a successful connection. */ 524 if (sock == -1) { 525 error("ssh: connect to host %s port %s: %s", 526 host, strport, errno == 0 ? "failure" : strerror(errno)); 527 return -1; 528 } 529 530 debug("Connection established."); 531 532 /* Set SO_KEEPALIVE if requested. */ 533 if (want_keepalive && 534 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 535 sizeof(on)) < 0) 536 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 537 538 /* Set the connection. */ 539 if (ssh_packet_set_connection(ssh, sock, sock) == NULL) 540 return -1; /* ssh_packet_set_connection logs error */ 541 542 return 0; 543 } 544 545 int 546 ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs, 547 struct sockaddr_storage *hostaddr, u_short port, int family, 548 int connection_attempts, int *timeout_ms, int want_keepalive) 549 { 550 int in, out; 551 552 if (options.proxy_command == NULL) { 553 return ssh_connect_direct(ssh, host, addrs, hostaddr, port, 554 family, connection_attempts, timeout_ms, want_keepalive); 555 } else if (strcmp(options.proxy_command, "-") == 0) { 556 if ((in = dup(STDIN_FILENO)) < 0 || 557 (out = dup(STDOUT_FILENO)) < 0) { 558 if (in >= 0) 559 close(in); 560 error("%s: dup() in/out failed", __func__); 561 return -1; /* ssh_packet_set_connection logs error */ 562 } 563 if ((ssh_packet_set_connection(ssh, in, out)) == NULL) 564 return -1; /* ssh_packet_set_connection logs error */ 565 return 0; 566 } else if (options.proxy_use_fdpass) { 567 return ssh_proxy_fdpass_connect(ssh, host, port, 568 options.proxy_command); 569 } 570 return ssh_proxy_connect(ssh, host, port, options.proxy_command); 571 } 572 573 /* defaults to 'no' */ 574 static int 575 confirm(const char *prompt, const char *fingerprint) 576 { 577 const char *msg, *again = "Please type 'yes' or 'no': "; 578 const char *again_fp = "Please type 'yes', 'no' or the fingerprint: "; 579 char *p; 580 int ret = -1; 581 582 if (options.batch_mode) 583 return 0; 584 for (msg = prompt;;msg = fingerprint ? again_fp : again) { 585 p = read_passphrase(msg, RP_ECHO); 586 if (p == NULL) 587 return 0; 588 p[strcspn(p, "\n")] = '\0'; 589 if (p[0] == '\0' || strcasecmp(p, "no") == 0) 590 ret = 0; 591 else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL && 592 strcasecmp(p, fingerprint) == 0)) 593 ret = 1; 594 free(p); 595 if (ret != -1) 596 return ret; 597 } 598 } 599 600 static int 601 check_host_cert(const char *host, const struct sshkey *key) 602 { 603 const char *reason; 604 int r; 605 606 if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) { 607 error("%s", reason); 608 return 0; 609 } 610 if (sshbuf_len(key->cert->critical) != 0) { 611 error("Certificate for %s contains unsupported " 612 "critical options(s)", host); 613 return 0; 614 } 615 if ((r = sshkey_check_cert_sigtype(key, 616 options.ca_sign_algorithms)) != 0) { 617 logit("%s: certificate signature algorithm %s: %s", __func__, 618 (key->cert == NULL || key->cert->signature_type == NULL) ? 619 "(null)" : key->cert->signature_type, ssh_err(r)); 620 return 0; 621 } 622 623 return 1; 624 } 625 626 static int 627 sockaddr_is_local(struct sockaddr *hostaddr) 628 { 629 switch (hostaddr->sa_family) { 630 case AF_INET: 631 return (ntohl(((struct sockaddr_in *)hostaddr)-> 632 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 633 case AF_INET6: 634 return IN6_IS_ADDR_LOOPBACK( 635 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 636 default: 637 return 0; 638 } 639 } 640 641 /* 642 * Prepare the hostname and ip address strings that are used to lookup 643 * host keys in known_hosts files. These may have a port number appended. 644 */ 645 void 646 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 647 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 648 { 649 char ntop[NI_MAXHOST]; 650 socklen_t addrlen; 651 652 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) { 653 case -1: 654 addrlen = 0; 655 break; 656 case AF_INET: 657 addrlen = sizeof(struct sockaddr_in); 658 break; 659 case AF_INET6: 660 addrlen = sizeof(struct sockaddr_in6); 661 break; 662 default: 663 addrlen = sizeof(struct sockaddr); 664 break; 665 } 666 667 /* 668 * We don't have the remote ip-address for connections 669 * using a proxy command 670 */ 671 if (hostfile_ipaddr != NULL) { 672 if (options.proxy_command == NULL) { 673 if (getnameinfo(hostaddr, addrlen, 674 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 675 fatal("%s: getnameinfo failed", __func__); 676 *hostfile_ipaddr = put_host_port(ntop, port); 677 } else { 678 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 679 "command>"); 680 } 681 } 682 683 /* 684 * Allow the user to record the key under a different name or 685 * differentiate a non-standard port. This is useful for ssh 686 * tunneling over forwarded connections or if you run multiple 687 * sshd's on different ports on the same machine. 688 */ 689 if (hostfile_hostname != NULL) { 690 if (options.host_key_alias != NULL) { 691 *hostfile_hostname = xstrdup(options.host_key_alias); 692 debug("using hostkeyalias: %s", *hostfile_hostname); 693 } else { 694 *hostfile_hostname = put_host_port(hostname, port); 695 } 696 } 697 } 698 699 /* 700 * check whether the supplied host key is valid, return -1 if the key 701 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 702 */ 703 #define RDRW 0 704 #define RDONLY 1 705 #define ROQUIET 2 706 static int 707 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 708 struct sshkey *host_key, int readonly, 709 char **user_hostfiles, u_int num_user_hostfiles, 710 char **system_hostfiles, u_int num_system_hostfiles) 711 { 712 HostStatus host_status; 713 HostStatus ip_status; 714 struct sshkey *raw_key = NULL; 715 char *ip = NULL, *host = NULL; 716 char hostline[1000], *hostp, *fp, *ra; 717 char msg[1024]; 718 const char *type; 719 const struct hostkey_entry *host_found, *ip_found; 720 int len, cancelled_forwarding = 0, confirmed; 721 int local = sockaddr_is_local(hostaddr); 722 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0; 723 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 724 struct hostkeys *host_hostkeys, *ip_hostkeys; 725 u_int i; 726 727 /* 728 * Force accepting of the host key for loopback/localhost. The 729 * problem is that if the home directory is NFS-mounted to multiple 730 * machines, localhost will refer to a different machine in each of 731 * them, and the user will get bogus HOST_CHANGED warnings. This 732 * essentially disables host authentication for localhost; however, 733 * this is probably not a real problem. 734 */ 735 if (options.no_host_authentication_for_localhost == 1 && local && 736 options.host_key_alias == NULL) { 737 debug("Forcing accepting of host key for " 738 "loopback/localhost."); 739 return 0; 740 } 741 742 /* 743 * Prepare the hostname and address strings used for hostkey lookup. 744 * In some cases, these will have a port number appended. 745 */ 746 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 747 748 /* 749 * Turn off check_host_ip if the connection is to localhost, via proxy 750 * command or if we don't have a hostname to compare with 751 */ 752 if (options.check_host_ip && (local || 753 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 754 options.check_host_ip = 0; 755 756 host_hostkeys = init_hostkeys(); 757 for (i = 0; i < num_user_hostfiles; i++) 758 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 759 for (i = 0; i < num_system_hostfiles; i++) 760 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 761 762 ip_hostkeys = NULL; 763 if (!want_cert && options.check_host_ip) { 764 ip_hostkeys = init_hostkeys(); 765 for (i = 0; i < num_user_hostfiles; i++) 766 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 767 for (i = 0; i < num_system_hostfiles; i++) 768 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 769 } 770 771 retry: 772 /* Reload these as they may have changed on cert->key downgrade */ 773 want_cert = sshkey_is_cert(host_key); 774 type = sshkey_type(host_key); 775 776 /* 777 * Check if the host key is present in the user's list of known 778 * hosts or in the systemwide list. 779 */ 780 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 781 &host_found); 782 783 /* 784 * Also perform check for the ip address, skip the check if we are 785 * localhost, looking for a certificate, or the hostname was an ip 786 * address to begin with. 787 */ 788 if (!want_cert && ip_hostkeys != NULL) { 789 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 790 &ip_found); 791 if (host_status == HOST_CHANGED && 792 (ip_status != HOST_CHANGED || 793 (ip_found != NULL && 794 !sshkey_equal(ip_found->key, host_found->key)))) 795 host_ip_differ = 1; 796 } else 797 ip_status = host_status; 798 799 switch (host_status) { 800 case HOST_OK: 801 /* The host is known and the key matches. */ 802 debug("Host '%.200s' is known and matches the %s host %s.", 803 host, type, want_cert ? "certificate" : "key"); 804 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 805 host_found->file, host_found->line); 806 if (want_cert && 807 !check_host_cert(options.host_key_alias == NULL ? 808 hostname : options.host_key_alias, host_key)) 809 goto fail; 810 if (options.check_host_ip && ip_status == HOST_NEW) { 811 if (readonly || want_cert) 812 logit("%s host key for IP address " 813 "'%.128s' not in list of known hosts.", 814 type, ip); 815 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 816 host_key, options.hash_known_hosts)) 817 logit("Failed to add the %s host key for IP " 818 "address '%.128s' to the list of known " 819 "hosts (%.500s).", type, ip, 820 user_hostfiles[0]); 821 else 822 logit("Warning: Permanently added the %s host " 823 "key for IP address '%.128s' to the list " 824 "of known hosts.", type, ip); 825 } else if (options.visual_host_key) { 826 fp = sshkey_fingerprint(host_key, 827 options.fingerprint_hash, SSH_FP_DEFAULT); 828 ra = sshkey_fingerprint(host_key, 829 options.fingerprint_hash, SSH_FP_RANDOMART); 830 if (fp == NULL || ra == NULL) 831 fatal("%s: sshkey_fingerprint fail", __func__); 832 logit("Host key fingerprint is %s\n%s", fp, ra); 833 free(ra); 834 free(fp); 835 } 836 hostkey_trusted = 1; 837 break; 838 case HOST_NEW: 839 if (options.host_key_alias == NULL && port != 0 && 840 port != SSH_DEFAULT_PORT) { 841 debug("checking without port identifier"); 842 if (check_host_key(hostname, hostaddr, 0, host_key, 843 ROQUIET, user_hostfiles, num_user_hostfiles, 844 system_hostfiles, num_system_hostfiles) == 0) { 845 debug("found matching key w/out port"); 846 break; 847 } 848 } 849 if (readonly || want_cert) 850 goto fail; 851 /* The host is new. */ 852 if (options.strict_host_key_checking == 853 SSH_STRICT_HOSTKEY_YES) { 854 /* 855 * User has requested strict host key checking. We 856 * will not add the host key automatically. The only 857 * alternative left is to abort. 858 */ 859 error("No %s host key is known for %.200s and you " 860 "have requested strict checking.", type, host); 861 goto fail; 862 } else if (options.strict_host_key_checking == 863 SSH_STRICT_HOSTKEY_ASK) { 864 char msg1[1024], msg2[1024]; 865 866 if (show_other_keys(host_hostkeys, host_key)) 867 snprintf(msg1, sizeof(msg1), 868 "\nbut keys of different type are already" 869 " known for this host."); 870 else 871 snprintf(msg1, sizeof(msg1), "."); 872 /* The default */ 873 fp = sshkey_fingerprint(host_key, 874 options.fingerprint_hash, SSH_FP_DEFAULT); 875 ra = sshkey_fingerprint(host_key, 876 options.fingerprint_hash, SSH_FP_RANDOMART); 877 if (fp == NULL || ra == NULL) 878 fatal("%s: sshkey_fingerprint fail", __func__); 879 msg2[0] = '\0'; 880 if (options.verify_host_key_dns) { 881 if (matching_host_key_dns) 882 snprintf(msg2, sizeof(msg2), 883 "Matching host key fingerprint" 884 " found in DNS.\n"); 885 else 886 snprintf(msg2, sizeof(msg2), 887 "No matching host key fingerprint" 888 " found in DNS.\n"); 889 } 890 snprintf(msg, sizeof(msg), 891 "The authenticity of host '%.200s (%s)' can't be " 892 "established%s\n" 893 "%s key fingerprint is %s.%s%s\n%s" 894 "Are you sure you want to continue connecting " 895 "(yes/no/[fingerprint])? ", 896 host, ip, msg1, type, fp, 897 options.visual_host_key ? "\n" : "", 898 options.visual_host_key ? ra : "", 899 msg2); 900 free(ra); 901 confirmed = confirm(msg, fp); 902 free(fp); 903 if (!confirmed) 904 goto fail; 905 hostkey_trusted = 1; /* user explicitly confirmed */ 906 } 907 /* 908 * If in "new" or "off" strict mode, add the key automatically 909 * to the local known_hosts file. 910 */ 911 if (options.check_host_ip && ip_status == HOST_NEW) { 912 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 913 hostp = hostline; 914 if (options.hash_known_hosts) { 915 /* Add hash of host and IP separately */ 916 r = add_host_to_hostfile(user_hostfiles[0], 917 host, host_key, options.hash_known_hosts) && 918 add_host_to_hostfile(user_hostfiles[0], ip, 919 host_key, options.hash_known_hosts); 920 } else { 921 /* Add unhashed "host,ip" */ 922 r = add_host_to_hostfile(user_hostfiles[0], 923 hostline, host_key, 924 options.hash_known_hosts); 925 } 926 } else { 927 r = add_host_to_hostfile(user_hostfiles[0], host, 928 host_key, options.hash_known_hosts); 929 hostp = host; 930 } 931 932 if (!r) 933 logit("Failed to add the host to the list of known " 934 "hosts (%.500s).", user_hostfiles[0]); 935 else 936 logit("Warning: Permanently added '%.200s' (%s) to the " 937 "list of known hosts.", hostp, type); 938 break; 939 case HOST_REVOKED: 940 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 941 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 942 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 943 error("The %s host key for %s is marked as revoked.", type, host); 944 error("This could mean that a stolen key is being used to"); 945 error("impersonate this host."); 946 947 /* 948 * If strict host key checking is in use, the user will have 949 * to edit the key manually and we can only abort. 950 */ 951 if (options.strict_host_key_checking != 952 SSH_STRICT_HOSTKEY_OFF) { 953 error("%s host key for %.200s was revoked and you have " 954 "requested strict checking.", type, host); 955 goto fail; 956 } 957 goto continue_unsafe; 958 959 case HOST_CHANGED: 960 if (want_cert) { 961 /* 962 * This is only a debug() since it is valid to have 963 * CAs with wildcard DNS matches that don't match 964 * all hosts that one might visit. 965 */ 966 debug("Host certificate authority does not " 967 "match %s in %s:%lu", CA_MARKER, 968 host_found->file, host_found->line); 969 goto fail; 970 } 971 if (readonly == ROQUIET) 972 goto fail; 973 if (options.check_host_ip && host_ip_differ) { 974 char *key_msg; 975 if (ip_status == HOST_NEW) 976 key_msg = "is unknown"; 977 else if (ip_status == HOST_OK) 978 key_msg = "is unchanged"; 979 else 980 key_msg = "has a different value"; 981 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 982 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 983 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 984 error("The %s host key for %s has changed,", type, host); 985 error("and the key for the corresponding IP address %s", ip); 986 error("%s. This could either mean that", key_msg); 987 error("DNS SPOOFING is happening or the IP address for the host"); 988 error("and its host key have changed at the same time."); 989 if (ip_status != HOST_NEW) 990 error("Offending key for IP in %s:%lu", 991 ip_found->file, ip_found->line); 992 } 993 /* The host key has changed. */ 994 warn_changed_key(host_key); 995 error("Add correct host key in %.100s to get rid of this message.", 996 user_hostfiles[0]); 997 error("Offending %s key in %s:%lu", 998 sshkey_type(host_found->key), 999 host_found->file, host_found->line); 1000 1001 /* 1002 * If strict host key checking is in use, the user will have 1003 * to edit the key manually and we can only abort. 1004 */ 1005 if (options.strict_host_key_checking != 1006 SSH_STRICT_HOSTKEY_OFF) { 1007 error("%s host key for %.200s has changed and you have " 1008 "requested strict checking.", type, host); 1009 goto fail; 1010 } 1011 1012 continue_unsafe: 1013 /* 1014 * If strict host key checking has not been requested, allow 1015 * the connection but without MITM-able authentication or 1016 * forwarding. 1017 */ 1018 if (options.password_authentication) { 1019 error("Password authentication is disabled to avoid " 1020 "man-in-the-middle attacks."); 1021 options.password_authentication = 0; 1022 cancelled_forwarding = 1; 1023 } 1024 if (options.kbd_interactive_authentication) { 1025 error("Keyboard-interactive authentication is disabled" 1026 " to avoid man-in-the-middle attacks."); 1027 options.kbd_interactive_authentication = 0; 1028 options.challenge_response_authentication = 0; 1029 cancelled_forwarding = 1; 1030 } 1031 if (options.challenge_response_authentication) { 1032 error("Challenge/response authentication is disabled" 1033 " to avoid man-in-the-middle attacks."); 1034 options.challenge_response_authentication = 0; 1035 cancelled_forwarding = 1; 1036 } 1037 if (options.forward_agent) { 1038 error("Agent forwarding is disabled to avoid " 1039 "man-in-the-middle attacks."); 1040 options.forward_agent = 0; 1041 cancelled_forwarding = 1; 1042 } 1043 if (options.forward_x11) { 1044 error("X11 forwarding is disabled to avoid " 1045 "man-in-the-middle attacks."); 1046 options.forward_x11 = 0; 1047 cancelled_forwarding = 1; 1048 } 1049 if (options.num_local_forwards > 0 || 1050 options.num_remote_forwards > 0) { 1051 error("Port forwarding is disabled to avoid " 1052 "man-in-the-middle attacks."); 1053 options.num_local_forwards = 1054 options.num_remote_forwards = 0; 1055 cancelled_forwarding = 1; 1056 } 1057 if (options.tun_open != SSH_TUNMODE_NO) { 1058 error("Tunnel forwarding is disabled to avoid " 1059 "man-in-the-middle attacks."); 1060 options.tun_open = SSH_TUNMODE_NO; 1061 cancelled_forwarding = 1; 1062 } 1063 if (options.exit_on_forward_failure && cancelled_forwarding) 1064 fatal("Error: forwarding disabled due to host key " 1065 "check failure"); 1066 1067 /* 1068 * XXX Should permit the user to change to use the new id. 1069 * This could be done by converting the host key to an 1070 * identifying sentence, tell that the host identifies itself 1071 * by that sentence, and ask the user if he/she wishes to 1072 * accept the authentication. 1073 */ 1074 break; 1075 case HOST_FOUND: 1076 fatal("internal error"); 1077 break; 1078 } 1079 1080 if (options.check_host_ip && host_status != HOST_CHANGED && 1081 ip_status == HOST_CHANGED) { 1082 snprintf(msg, sizeof(msg), 1083 "Warning: the %s host key for '%.200s' " 1084 "differs from the key for the IP address '%.128s'" 1085 "\nOffending key for IP in %s:%lu", 1086 type, host, ip, ip_found->file, ip_found->line); 1087 if (host_status == HOST_OK) { 1088 len = strlen(msg); 1089 snprintf(msg + len, sizeof(msg) - len, 1090 "\nMatching host key in %s:%lu", 1091 host_found->file, host_found->line); 1092 } 1093 if (options.strict_host_key_checking == 1094 SSH_STRICT_HOSTKEY_ASK) { 1095 strlcat(msg, "\nAre you sure you want " 1096 "to continue connecting (yes/no)? ", sizeof(msg)); 1097 if (!confirm(msg, NULL)) 1098 goto fail; 1099 } else if (options.strict_host_key_checking != 1100 SSH_STRICT_HOSTKEY_OFF) { 1101 logit("%s", msg); 1102 error("Exiting, you have requested strict checking."); 1103 goto fail; 1104 } else { 1105 logit("%s", msg); 1106 } 1107 } 1108 1109 if (!hostkey_trusted && options.update_hostkeys) { 1110 debug("%s: hostkey not known or explicitly trusted: " 1111 "disabling UpdateHostkeys", __func__); 1112 options.update_hostkeys = 0; 1113 } 1114 1115 free(ip); 1116 free(host); 1117 if (host_hostkeys != NULL) 1118 free_hostkeys(host_hostkeys); 1119 if (ip_hostkeys != NULL) 1120 free_hostkeys(ip_hostkeys); 1121 return 0; 1122 1123 fail: 1124 if (want_cert && host_status != HOST_REVOKED) { 1125 /* 1126 * No matching certificate. Downgrade cert to raw key and 1127 * search normally. 1128 */ 1129 debug("No matching CA found. Retry with plain key"); 1130 if ((r = sshkey_from_private(host_key, &raw_key)) != 0) 1131 fatal("%s: sshkey_from_private: %s", 1132 __func__, ssh_err(r)); 1133 if ((r = sshkey_drop_cert(raw_key)) != 0) 1134 fatal("Couldn't drop certificate: %s", ssh_err(r)); 1135 host_key = raw_key; 1136 goto retry; 1137 } 1138 sshkey_free(raw_key); 1139 free(ip); 1140 free(host); 1141 if (host_hostkeys != NULL) 1142 free_hostkeys(host_hostkeys); 1143 if (ip_hostkeys != NULL) 1144 free_hostkeys(ip_hostkeys); 1145 return -1; 1146 } 1147 1148 /* returns 0 if key verifies or -1 if key does NOT verify */ 1149 int 1150 verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key) 1151 { 1152 u_int i; 1153 int r = -1, flags = 0; 1154 char valid[64], *fp = NULL, *cafp = NULL; 1155 struct sshkey *plain = NULL; 1156 1157 if ((fp = sshkey_fingerprint(host_key, 1158 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1159 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1160 r = -1; 1161 goto out; 1162 } 1163 1164 if (sshkey_is_cert(host_key)) { 1165 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1166 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1167 error("%s: fingerprint CA key: %s", 1168 __func__, ssh_err(r)); 1169 r = -1; 1170 goto out; 1171 } 1172 sshkey_format_cert_validity(host_key->cert, 1173 valid, sizeof(valid)); 1174 debug("Server host certificate: %s %s, serial %llu " 1175 "ID \"%s\" CA %s %s valid %s", 1176 sshkey_ssh_name(host_key), fp, 1177 (unsigned long long)host_key->cert->serial, 1178 host_key->cert->key_id, 1179 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1180 valid); 1181 for (i = 0; i < host_key->cert->nprincipals; i++) { 1182 debug2("Server host certificate hostname: %s", 1183 host_key->cert->principals[i]); 1184 } 1185 } else { 1186 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp); 1187 } 1188 1189 if (sshkey_equal(previous_host_key, host_key)) { 1190 debug2("%s: server host key %s %s matches cached key", 1191 __func__, sshkey_type(host_key), fp); 1192 r = 0; 1193 goto out; 1194 } 1195 1196 /* Check in RevokedHostKeys file if specified */ 1197 if (options.revoked_host_keys != NULL) { 1198 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1199 switch (r) { 1200 case 0: 1201 break; /* not revoked */ 1202 case SSH_ERR_KEY_REVOKED: 1203 error("Host key %s %s revoked by file %s", 1204 sshkey_type(host_key), fp, 1205 options.revoked_host_keys); 1206 r = -1; 1207 goto out; 1208 default: 1209 error("Error checking host key %s %s in " 1210 "revoked keys file %s: %s", sshkey_type(host_key), 1211 fp, options.revoked_host_keys, ssh_err(r)); 1212 r = -1; 1213 goto out; 1214 } 1215 } 1216 1217 if (options.verify_host_key_dns) { 1218 /* 1219 * XXX certs are not yet supported for DNS, so downgrade 1220 * them and try the plain key. 1221 */ 1222 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1223 goto out; 1224 if (sshkey_is_cert(plain)) 1225 sshkey_drop_cert(plain); 1226 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1227 if (flags & DNS_VERIFY_FOUND) { 1228 if (options.verify_host_key_dns == 1 && 1229 flags & DNS_VERIFY_MATCH && 1230 flags & DNS_VERIFY_SECURE) { 1231 r = 0; 1232 goto out; 1233 } 1234 if (flags & DNS_VERIFY_MATCH) { 1235 matching_host_key_dns = 1; 1236 } else { 1237 warn_changed_key(plain); 1238 error("Update the SSHFP RR in DNS " 1239 "with the new host key to get rid " 1240 "of this message."); 1241 } 1242 } 1243 } 1244 } 1245 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1246 options.user_hostfiles, options.num_user_hostfiles, 1247 options.system_hostfiles, options.num_system_hostfiles); 1248 1249 out: 1250 sshkey_free(plain); 1251 free(fp); 1252 free(cafp); 1253 if (r == 0 && host_key != NULL) { 1254 sshkey_free(previous_host_key); 1255 r = sshkey_from_private(host_key, &previous_host_key); 1256 } 1257 1258 return r; 1259 } 1260 1261 /* 1262 * Starts a dialog with the server, and authenticates the current user on the 1263 * server. This does not need any extra privileges. The basic connection 1264 * to the server must already have been established before this is called. 1265 * If login fails, this function prints an error and never returns. 1266 * This function does not require super-user privileges. 1267 */ 1268 void 1269 ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost, 1270 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1271 { 1272 char *host; 1273 char *server_user, *local_user; 1274 1275 local_user = xstrdup(pw->pw_name); 1276 server_user = options.user ? options.user : local_user; 1277 1278 /* Convert the user-supplied hostname into all lowercase. */ 1279 host = xstrdup(orighost); 1280 lowercase(host); 1281 1282 /* Exchange protocol version identification strings with the server. */ 1283 if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0) 1284 cleanup_exit(255); /* error already logged */ 1285 1286 /* Put the connection into non-blocking mode. */ 1287 ssh_packet_set_nonblocking(ssh); 1288 1289 /* key exchange */ 1290 /* authenticate user */ 1291 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1292 ssh_kex2(ssh, host, hostaddr, port); 1293 ssh_userauth2(ssh, local_user, server_user, host, sensitive); 1294 free(local_user); 1295 } 1296 1297 /* print all known host keys for a given host, but skip keys of given type */ 1298 static int 1299 show_other_keys(struct hostkeys *hostkeys, struct sshkey *key) 1300 { 1301 int type[] = { 1302 KEY_RSA, 1303 KEY_DSA, 1304 KEY_ECDSA, 1305 KEY_ED25519, 1306 KEY_XMSS, 1307 -1 1308 }; 1309 int i, ret = 0; 1310 char *fp, *ra; 1311 const struct hostkey_entry *found; 1312 1313 for (i = 0; type[i] != -1; i++) { 1314 if (type[i] == key->type) 1315 continue; 1316 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1317 continue; 1318 fp = sshkey_fingerprint(found->key, 1319 options.fingerprint_hash, SSH_FP_DEFAULT); 1320 ra = sshkey_fingerprint(found->key, 1321 options.fingerprint_hash, SSH_FP_RANDOMART); 1322 if (fp == NULL || ra == NULL) 1323 fatal("%s: sshkey_fingerprint fail", __func__); 1324 logit("WARNING: %s key found for host %s\n" 1325 "in %s:%lu\n" 1326 "%s key fingerprint %s.", 1327 sshkey_type(found->key), 1328 found->host, found->file, found->line, 1329 sshkey_type(found->key), fp); 1330 if (options.visual_host_key) 1331 logit("%s", ra); 1332 free(ra); 1333 free(fp); 1334 ret = 1; 1335 } 1336 return ret; 1337 } 1338 1339 static void 1340 warn_changed_key(struct sshkey *host_key) 1341 { 1342 char *fp; 1343 1344 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1345 SSH_FP_DEFAULT); 1346 if (fp == NULL) 1347 fatal("%s: sshkey_fingerprint fail", __func__); 1348 1349 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1350 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1351 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1352 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1353 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1354 error("It is also possible that a host key has just been changed."); 1355 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1356 sshkey_type(host_key), fp); 1357 error("Please contact your system administrator."); 1358 1359 free(fp); 1360 } 1361 1362 /* 1363 * Execute a local command 1364 */ 1365 int 1366 ssh_local_cmd(const char *args) 1367 { 1368 char *shell; 1369 pid_t pid; 1370 int status; 1371 void (*osighand)(int); 1372 1373 if (!options.permit_local_command || 1374 args == NULL || !*args) 1375 return (1); 1376 1377 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1378 shell = _PATH_BSHELL; 1379 1380 osighand = signal(SIGCHLD, SIG_DFL); 1381 pid = fork(); 1382 if (pid == 0) { 1383 signal(SIGPIPE, SIG_DFL); 1384 debug3("Executing %s -c \"%s\"", shell, args); 1385 execl(shell, shell, "-c", args, (char *)NULL); 1386 error("Couldn't execute %s -c \"%s\": %s", 1387 shell, args, strerror(errno)); 1388 _exit(1); 1389 } else if (pid == -1) 1390 fatal("fork failed: %.100s", strerror(errno)); 1391 while (waitpid(pid, &status, 0) == -1) 1392 if (errno != EINTR) 1393 fatal("Couldn't wait for child: %s", strerror(errno)); 1394 signal(SIGCHLD, osighand); 1395 1396 if (!WIFEXITED(status)) 1397 return (1); 1398 1399 return (WEXITSTATUS(status)); 1400 } 1401 1402 void 1403 maybe_add_key_to_agent(char *authfile, const struct sshkey *private, 1404 char *comment, char *passphrase) 1405 { 1406 int auth_sock = -1, r; 1407 1408 if (options.add_keys_to_agent == 0) 1409 return; 1410 1411 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1412 debug3("no authentication agent, not adding key"); 1413 return; 1414 } 1415 1416 if (options.add_keys_to_agent == 2 && 1417 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1418 debug3("user denied adding this key"); 1419 close(auth_sock); 1420 return; 1421 } 1422 1423 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0, 1424 (options.add_keys_to_agent == 3), 0)) == 0) 1425 debug("identity added to agent: %s", authfile); 1426 else 1427 debug("could not add identity to agent: %s (%d)", authfile, r); 1428 close(auth_sock); 1429 } 1430