1 /* $OpenBSD: sshconnect.c,v 1.323 2019/11/13 04:47:52 deraadt 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 <sys/types.h> 17 #include <sys/wait.h> 18 #include <sys/stat.h> 19 #include <sys/socket.h> 20 #include <sys/time.h> 21 22 #include <net/if.h> 23 #include <netinet/in.h> 24 25 #include <ctype.h> 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <netdb.h> 29 #include <paths.h> 30 #include <signal.h> 31 #include <pwd.h> 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <stdarg.h> 35 #include <string.h> 36 #include <unistd.h> 37 #include <ifaddrs.h> 38 39 #include "xmalloc.h" 40 #include "ssh.h" 41 #include "sshbuf.h" 42 #include "packet.h" 43 #include "compat.h" 44 #include "sshkey.h" 45 #include "sshconnect.h" 46 #include "hostfile.h" 47 #include "log.h" 48 #include "misc.h" 49 #include "readconf.h" 50 #include "atomicio.h" 51 #include "dns.h" 52 #include "monitor_fdpass.h" 53 #include "ssh2.h" 54 #include "version.h" 55 #include "authfile.h" 56 #include "ssherr.h" 57 #include "authfd.h" 58 #include "kex.h" 59 60 struct sshkey *previous_host_key = NULL; 61 62 static int matching_host_key_dns = 0; 63 64 static pid_t proxy_command_pid = 0; 65 66 /* import */ 67 extern int debug_flag; 68 extern Options options; 69 extern char *__progname; 70 71 static int show_other_keys(struct hostkeys *, struct sshkey *); 72 static void warn_changed_key(struct sshkey *); 73 74 /* Expand a proxy command */ 75 static char * 76 expand_proxy_command(const char *proxy_command, const char *user, 77 const char *host, const char *host_arg, int port) 78 { 79 char *tmp, *ret, strport[NI_MAXSERV]; 80 81 snprintf(strport, sizeof strport, "%d", port); 82 xasprintf(&tmp, "exec %s", proxy_command); 83 ret = percent_expand(tmp, 84 "h", host, 85 "n", host_arg, 86 "p", strport, 87 "r", options.user, 88 (char *)NULL); 89 free(tmp); 90 return ret; 91 } 92 93 static void 94 stderr_null(void) 95 { 96 int devnull; 97 98 if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) { 99 error("Can't open %s for stderr redirection: %s", 100 _PATH_DEVNULL, strerror(errno)); 101 return; 102 } 103 if (devnull == STDERR_FILENO) 104 return; 105 if (dup2(devnull, STDERR_FILENO) == -1) 106 error("Cannot redirect stderr to %s", _PATH_DEVNULL); 107 if (devnull > STDERR_FILENO) 108 close(devnull); 109 } 110 111 /* 112 * Connect to the given ssh server using a proxy command that passes a 113 * a connected fd back to us. 114 */ 115 static int 116 ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, 117 const char *host_arg, u_short port, const char *proxy_command) 118 { 119 char *command_string; 120 int sp[2], sock; 121 pid_t pid; 122 char *shell; 123 124 if ((shell = getenv("SHELL")) == NULL) 125 shell = _PATH_BSHELL; 126 127 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1) 128 fatal("Could not create socketpair to communicate with " 129 "proxy dialer: %.100s", strerror(errno)); 130 131 command_string = expand_proxy_command(proxy_command, options.user, 132 host_arg, host, port); 133 debug("Executing proxy dialer command: %.500s", command_string); 134 135 /* Fork and execute the proxy command. */ 136 if ((pid = fork()) == 0) { 137 char *argv[10]; 138 139 close(sp[1]); 140 /* Redirect stdin and stdout. */ 141 if (sp[0] != 0) { 142 if (dup2(sp[0], 0) == -1) 143 perror("dup2 stdin"); 144 } 145 if (sp[0] != 1) { 146 if (dup2(sp[0], 1) == -1) 147 perror("dup2 stdout"); 148 } 149 if (sp[0] >= 2) 150 close(sp[0]); 151 152 /* 153 * Stderr is left for non-ControlPersist connections is so 154 * error messages may be printed on the user's terminal. 155 */ 156 if (!debug_flag && options.control_path != NULL && 157 options.control_persist) 158 stderr_null(); 159 160 argv[0] = shell; 161 argv[1] = "-c"; 162 argv[2] = command_string; 163 argv[3] = NULL; 164 165 /* 166 * Execute the proxy command. 167 * Note that we gave up any extra privileges above. 168 */ 169 execv(argv[0], argv); 170 perror(argv[0]); 171 exit(1); 172 } 173 /* Parent. */ 174 if (pid == -1) 175 fatal("fork failed: %.100s", strerror(errno)); 176 close(sp[0]); 177 free(command_string); 178 179 if ((sock = mm_receive_fd(sp[1])) == -1) 180 fatal("proxy dialer did not pass back a connection"); 181 close(sp[1]); 182 183 while (waitpid(pid, NULL, 0) == -1) 184 if (errno != EINTR) 185 fatal("Couldn't wait for child: %s", strerror(errno)); 186 187 /* Set the connection file descriptors. */ 188 if (ssh_packet_set_connection(ssh, sock, sock) == NULL) 189 return -1; /* ssh_packet_set_connection logs error */ 190 191 return 0; 192 } 193 194 /* 195 * Connect to the given ssh server using a proxy command. 196 */ 197 static int 198 ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg, 199 u_short port, const char *proxy_command) 200 { 201 char *command_string; 202 int pin[2], pout[2]; 203 pid_t pid; 204 char *shell; 205 206 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 207 shell = _PATH_BSHELL; 208 209 /* Create pipes for communicating with the proxy. */ 210 if (pipe(pin) == -1 || pipe(pout) == -1) 211 fatal("Could not create pipes to communicate with the proxy: %.100s", 212 strerror(errno)); 213 214 command_string = expand_proxy_command(proxy_command, options.user, 215 host_arg, host, port); 216 debug("Executing proxy command: %.500s", command_string); 217 218 /* Fork and execute the proxy command. */ 219 if ((pid = fork()) == 0) { 220 char *argv[10]; 221 222 /* Redirect stdin and stdout. */ 223 close(pin[1]); 224 if (pin[0] != 0) { 225 if (dup2(pin[0], 0) == -1) 226 perror("dup2 stdin"); 227 close(pin[0]); 228 } 229 close(pout[0]); 230 if (dup2(pout[1], 1) == -1) 231 perror("dup2 stdout"); 232 /* Cannot be 1 because pin allocated two descriptors. */ 233 close(pout[1]); 234 235 /* 236 * Stderr is left for non-ControlPersist connections is so 237 * error messages may be printed on the user's terminal. 238 */ 239 if (!debug_flag && options.control_path != NULL && 240 options.control_persist) 241 stderr_null(); 242 243 argv[0] = shell; 244 argv[1] = "-c"; 245 argv[2] = command_string; 246 argv[3] = NULL; 247 248 /* Execute the proxy command. Note that we gave up any 249 extra privileges above. */ 250 signal(SIGPIPE, SIG_DFL); 251 execv(argv[0], argv); 252 perror(argv[0]); 253 exit(1); 254 } 255 /* Parent. */ 256 if (pid == -1) 257 fatal("fork failed: %.100s", strerror(errno)); 258 else 259 proxy_command_pid = pid; /* save pid to clean up later */ 260 261 /* Close child side of the descriptors. */ 262 close(pin[0]); 263 close(pout[1]); 264 265 /* Free the command name. */ 266 free(command_string); 267 268 /* Set the connection file descriptors. */ 269 if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL) 270 return -1; /* ssh_packet_set_connection logs error */ 271 272 return 0; 273 } 274 275 void 276 ssh_kill_proxy_command(void) 277 { 278 /* 279 * Send SIGHUP to proxy command if used. We don't wait() in 280 * case it hangs and instead rely on init to reap the child 281 */ 282 if (proxy_command_pid > 1) 283 kill(proxy_command_pid, SIGHUP); 284 } 285 286 /* 287 * Search a interface address list (returned from getifaddrs(3)) for an 288 * address that matches the desired address family on the specified interface. 289 * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure. 290 */ 291 static int 292 check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs, 293 struct sockaddr_storage *resultp, socklen_t *rlenp) 294 { 295 struct sockaddr_in6 *sa6; 296 struct sockaddr_in *sa; 297 struct in6_addr *v6addr; 298 const struct ifaddrs *ifa; 299 int allow_local; 300 301 /* 302 * Prefer addresses that are not loopback or linklocal, but use them 303 * if nothing else matches. 304 */ 305 for (allow_local = 0; allow_local < 2; allow_local++) { 306 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 307 if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL || 308 (ifa->ifa_flags & IFF_UP) == 0 || 309 ifa->ifa_addr->sa_family != af || 310 strcmp(ifa->ifa_name, options.bind_interface) != 0) 311 continue; 312 switch (ifa->ifa_addr->sa_family) { 313 case AF_INET: 314 sa = (struct sockaddr_in *)ifa->ifa_addr; 315 if (!allow_local && sa->sin_addr.s_addr == 316 htonl(INADDR_LOOPBACK)) 317 continue; 318 if (*rlenp < sizeof(struct sockaddr_in)) { 319 error("%s: v4 addr doesn't fit", 320 __func__); 321 return -1; 322 } 323 *rlenp = sizeof(struct sockaddr_in); 324 memcpy(resultp, sa, *rlenp); 325 return 0; 326 case AF_INET6: 327 sa6 = (struct sockaddr_in6 *)ifa->ifa_addr; 328 v6addr = &sa6->sin6_addr; 329 if (!allow_local && 330 (IN6_IS_ADDR_LINKLOCAL(v6addr) || 331 IN6_IS_ADDR_LOOPBACK(v6addr))) 332 continue; 333 if (*rlenp < sizeof(struct sockaddr_in6)) { 334 error("%s: v6 addr doesn't fit", 335 __func__); 336 return -1; 337 } 338 *rlenp = sizeof(struct sockaddr_in6); 339 memcpy(resultp, sa6, *rlenp); 340 return 0; 341 } 342 } 343 } 344 return -1; 345 } 346 347 /* 348 * Creates a socket for use as the ssh connection. 349 */ 350 static int 351 ssh_create_socket(struct addrinfo *ai) 352 { 353 int sock, r; 354 struct sockaddr_storage bindaddr; 355 socklen_t bindaddrlen = 0; 356 struct addrinfo hints, *res = NULL; 357 struct ifaddrs *ifaddrs = NULL; 358 char ntop[NI_MAXHOST]; 359 360 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 361 if (sock == -1) { 362 error("socket: %s", strerror(errno)); 363 return -1; 364 } 365 fcntl(sock, F_SETFD, FD_CLOEXEC); 366 367 /* Bind the socket to an alternative local IP address */ 368 if (options.bind_address == NULL && options.bind_interface == NULL) 369 return sock; 370 371 if (options.bind_address != NULL) { 372 memset(&hints, 0, sizeof(hints)); 373 hints.ai_family = ai->ai_family; 374 hints.ai_socktype = ai->ai_socktype; 375 hints.ai_protocol = ai->ai_protocol; 376 hints.ai_flags = AI_PASSIVE; 377 if ((r = getaddrinfo(options.bind_address, NULL, 378 &hints, &res)) != 0) { 379 error("getaddrinfo: %s: %s", options.bind_address, 380 ssh_gai_strerror(r)); 381 goto fail; 382 } 383 if (res == NULL) { 384 error("getaddrinfo: no addrs"); 385 goto fail; 386 } 387 memcpy(&bindaddr, res->ai_addr, res->ai_addrlen); 388 bindaddrlen = res->ai_addrlen; 389 } else if (options.bind_interface != NULL) { 390 if ((r = getifaddrs(&ifaddrs)) != 0) { 391 error("getifaddrs: %s: %s", options.bind_interface, 392 strerror(errno)); 393 goto fail; 394 } 395 bindaddrlen = sizeof(bindaddr); 396 if (check_ifaddrs(options.bind_interface, ai->ai_family, 397 ifaddrs, &bindaddr, &bindaddrlen) != 0) { 398 logit("getifaddrs: %s: no suitable addresses", 399 options.bind_interface); 400 goto fail; 401 } 402 } 403 if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen, 404 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) { 405 error("%s: getnameinfo failed: %s", __func__, 406 ssh_gai_strerror(r)); 407 goto fail; 408 } 409 if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) { 410 error("bind %s: %s", ntop, strerror(errno)); 411 goto fail; 412 } 413 debug("%s: bound to %s", __func__, ntop); 414 /* success */ 415 goto out; 416 fail: 417 close(sock); 418 sock = -1; 419 out: 420 if (res != NULL) 421 freeaddrinfo(res); 422 if (ifaddrs != NULL) 423 freeifaddrs(ifaddrs); 424 return sock; 425 } 426 427 /* 428 * Opens a TCP/IP connection to the remote server on the given host. 429 * The address of the remote host will be returned in hostaddr. 430 * If port is 0, the default port will be used. 431 * Connection_attempts specifies the maximum number of tries (one per 432 * second). If proxy_command is non-NULL, it specifies the command (with %h 433 * and %p substituted for host and port, respectively) to use to contact 434 * the daemon. 435 */ 436 static int 437 ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop, 438 struct sockaddr_storage *hostaddr, u_short port, int family, 439 int connection_attempts, int *timeout_ms, int want_keepalive) 440 { 441 int on = 1, saved_timeout_ms = *timeout_ms; 442 int oerrno, sock = -1, attempt; 443 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 444 struct addrinfo *ai; 445 446 debug2("%s", __func__); 447 memset(ntop, 0, sizeof(ntop)); 448 memset(strport, 0, sizeof(strport)); 449 450 for (attempt = 0; attempt < connection_attempts; attempt++) { 451 if (attempt > 0) { 452 /* Sleep a moment before retrying. */ 453 sleep(1); 454 debug("Trying again..."); 455 } 456 /* 457 * Loop through addresses for this host, and try each one in 458 * sequence until the connection succeeds. 459 */ 460 for (ai = aitop; ai; ai = ai->ai_next) { 461 if (ai->ai_family != AF_INET && 462 ai->ai_family != AF_INET6) { 463 errno = EAFNOSUPPORT; 464 continue; 465 } 466 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 467 ntop, sizeof(ntop), strport, sizeof(strport), 468 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 469 oerrno = errno; 470 error("%s: getnameinfo failed", __func__); 471 errno = oerrno; 472 continue; 473 } 474 debug("Connecting to %.200s [%.100s] port %s.", 475 host, ntop, strport); 476 477 /* Create a socket for connecting. */ 478 sock = ssh_create_socket(ai); 479 if (sock < 0) { 480 /* Any error is already output */ 481 errno = 0; 482 continue; 483 } 484 485 *timeout_ms = saved_timeout_ms; 486 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 487 timeout_ms) >= 0) { 488 /* Successful connection. */ 489 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 490 break; 491 } else { 492 oerrno = errno; 493 debug("connect to address %s port %s: %s", 494 ntop, strport, strerror(errno)); 495 close(sock); 496 sock = -1; 497 errno = oerrno; 498 } 499 } 500 if (sock != -1) 501 break; /* Successful connection. */ 502 } 503 504 /* Return failure if we didn't get a successful connection. */ 505 if (sock == -1) { 506 error("ssh: connect to host %s port %s: %s", 507 host, strport, errno == 0 ? "failure" : strerror(errno)); 508 return -1; 509 } 510 511 debug("Connection established."); 512 513 /* Set SO_KEEPALIVE if requested. */ 514 if (want_keepalive && 515 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 516 sizeof(on)) == -1) 517 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 518 519 /* Set the connection. */ 520 if (ssh_packet_set_connection(ssh, sock, sock) == NULL) 521 return -1; /* ssh_packet_set_connection logs error */ 522 523 return 0; 524 } 525 526 int 527 ssh_connect(struct ssh *ssh, const char *host, const char *host_arg, 528 struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port, 529 int family, int connection_attempts, int *timeout_ms, int want_keepalive) 530 { 531 int in, out; 532 533 if (options.proxy_command == NULL) { 534 return ssh_connect_direct(ssh, host, addrs, hostaddr, port, 535 family, connection_attempts, timeout_ms, want_keepalive); 536 } else if (strcmp(options.proxy_command, "-") == 0) { 537 if ((in = dup(STDIN_FILENO)) == -1 || 538 (out = dup(STDOUT_FILENO)) == -1) { 539 if (in >= 0) 540 close(in); 541 error("%s: dup() in/out failed", __func__); 542 return -1; /* ssh_packet_set_connection logs error */ 543 } 544 if ((ssh_packet_set_connection(ssh, in, out)) == NULL) 545 return -1; /* ssh_packet_set_connection logs error */ 546 return 0; 547 } else if (options.proxy_use_fdpass) { 548 return ssh_proxy_fdpass_connect(ssh, host, host_arg, port, 549 options.proxy_command); 550 } 551 return ssh_proxy_connect(ssh, host, host_arg, port, 552 options.proxy_command); 553 } 554 555 /* defaults to 'no' */ 556 static int 557 confirm(const char *prompt, const char *fingerprint) 558 { 559 const char *msg, *again = "Please type 'yes' or 'no': "; 560 const char *again_fp = "Please type 'yes', 'no' or the fingerprint: "; 561 char *p; 562 int ret = -1; 563 564 if (options.batch_mode) 565 return 0; 566 for (msg = prompt;;msg = fingerprint ? again_fp : again) { 567 p = read_passphrase(msg, RP_ECHO); 568 if (p == NULL) 569 return 0; 570 p[strcspn(p, "\n")] = '\0'; 571 if (p[0] == '\0' || strcasecmp(p, "no") == 0) 572 ret = 0; 573 else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL && 574 strcasecmp(p, fingerprint) == 0)) 575 ret = 1; 576 free(p); 577 if (ret != -1) 578 return ret; 579 } 580 } 581 582 static int 583 check_host_cert(const char *host, const struct sshkey *key) 584 { 585 const char *reason; 586 int r; 587 588 if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) { 589 error("%s", reason); 590 return 0; 591 } 592 if (sshbuf_len(key->cert->critical) != 0) { 593 error("Certificate for %s contains unsupported " 594 "critical options(s)", host); 595 return 0; 596 } 597 if ((r = sshkey_check_cert_sigtype(key, 598 options.ca_sign_algorithms)) != 0) { 599 logit("%s: certificate signature algorithm %s: %s", __func__, 600 (key->cert == NULL || key->cert->signature_type == NULL) ? 601 "(null)" : key->cert->signature_type, ssh_err(r)); 602 return 0; 603 } 604 605 return 1; 606 } 607 608 static int 609 sockaddr_is_local(struct sockaddr *hostaddr) 610 { 611 switch (hostaddr->sa_family) { 612 case AF_INET: 613 return (ntohl(((struct sockaddr_in *)hostaddr)-> 614 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 615 case AF_INET6: 616 return IN6_IS_ADDR_LOOPBACK( 617 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 618 default: 619 return 0; 620 } 621 } 622 623 /* 624 * Prepare the hostname and ip address strings that are used to lookup 625 * host keys in known_hosts files. These may have a port number appended. 626 */ 627 void 628 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 629 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 630 { 631 char ntop[NI_MAXHOST]; 632 633 /* 634 * We don't have the remote ip-address for connections 635 * using a proxy command 636 */ 637 if (hostfile_ipaddr != NULL) { 638 if (options.proxy_command == NULL) { 639 if (getnameinfo(hostaddr, hostaddr->sa_len, 640 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 641 fatal("%s: getnameinfo failed", __func__); 642 *hostfile_ipaddr = put_host_port(ntop, port); 643 } else { 644 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 645 "command>"); 646 } 647 } 648 649 /* 650 * Allow the user to record the key under a different name or 651 * differentiate a non-standard port. This is useful for ssh 652 * tunneling over forwarded connections or if you run multiple 653 * sshd's on different ports on the same machine. 654 */ 655 if (hostfile_hostname != NULL) { 656 if (options.host_key_alias != NULL) { 657 *hostfile_hostname = xstrdup(options.host_key_alias); 658 debug("using hostkeyalias: %s", *hostfile_hostname); 659 } else { 660 *hostfile_hostname = put_host_port(hostname, port); 661 } 662 } 663 } 664 665 /* 666 * check whether the supplied host key is valid, return -1 if the key 667 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 668 */ 669 #define RDRW 0 670 #define RDONLY 1 671 #define ROQUIET 2 672 static int 673 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 674 struct sshkey *host_key, int readonly, 675 char **user_hostfiles, u_int num_user_hostfiles, 676 char **system_hostfiles, u_int num_system_hostfiles) 677 { 678 HostStatus host_status; 679 HostStatus ip_status; 680 struct sshkey *raw_key = NULL; 681 char *ip = NULL, *host = NULL; 682 char hostline[1000], *hostp, *fp, *ra; 683 char msg[1024]; 684 const char *type; 685 const struct hostkey_entry *host_found, *ip_found; 686 int len, cancelled_forwarding = 0, confirmed; 687 int local = sockaddr_is_local(hostaddr); 688 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0; 689 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 690 struct hostkeys *host_hostkeys, *ip_hostkeys; 691 u_int i; 692 693 /* 694 * Force accepting of the host key for loopback/localhost. The 695 * problem is that if the home directory is NFS-mounted to multiple 696 * machines, localhost will refer to a different machine in each of 697 * them, and the user will get bogus HOST_CHANGED warnings. This 698 * essentially disables host authentication for localhost; however, 699 * this is probably not a real problem. 700 */ 701 if (options.no_host_authentication_for_localhost == 1 && local && 702 options.host_key_alias == NULL) { 703 debug("Forcing accepting of host key for " 704 "loopback/localhost."); 705 return 0; 706 } 707 708 /* 709 * Prepare the hostname and address strings used for hostkey lookup. 710 * In some cases, these will have a port number appended. 711 */ 712 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 713 714 /* 715 * Turn off check_host_ip if the connection is to localhost, via proxy 716 * command or if we don't have a hostname to compare with 717 */ 718 if (options.check_host_ip && (local || 719 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 720 options.check_host_ip = 0; 721 722 host_hostkeys = init_hostkeys(); 723 for (i = 0; i < num_user_hostfiles; i++) 724 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 725 for (i = 0; i < num_system_hostfiles; i++) 726 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 727 728 ip_hostkeys = NULL; 729 if (!want_cert && options.check_host_ip) { 730 ip_hostkeys = init_hostkeys(); 731 for (i = 0; i < num_user_hostfiles; i++) 732 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 733 for (i = 0; i < num_system_hostfiles; i++) 734 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 735 } 736 737 retry: 738 /* Reload these as they may have changed on cert->key downgrade */ 739 want_cert = sshkey_is_cert(host_key); 740 type = sshkey_type(host_key); 741 742 /* 743 * Check if the host key is present in the user's list of known 744 * hosts or in the systemwide list. 745 */ 746 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 747 &host_found); 748 749 /* 750 * Also perform check for the ip address, skip the check if we are 751 * localhost, looking for a certificate, or the hostname was an ip 752 * address to begin with. 753 */ 754 if (!want_cert && ip_hostkeys != NULL) { 755 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 756 &ip_found); 757 if (host_status == HOST_CHANGED && 758 (ip_status != HOST_CHANGED || 759 (ip_found != NULL && 760 !sshkey_equal(ip_found->key, host_found->key)))) 761 host_ip_differ = 1; 762 } else 763 ip_status = host_status; 764 765 switch (host_status) { 766 case HOST_OK: 767 /* The host is known and the key matches. */ 768 debug("Host '%.200s' is known and matches the %s host %s.", 769 host, type, want_cert ? "certificate" : "key"); 770 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 771 host_found->file, host_found->line); 772 if (want_cert && 773 !check_host_cert(options.host_key_alias == NULL ? 774 hostname : options.host_key_alias, host_key)) 775 goto fail; 776 if (options.check_host_ip && ip_status == HOST_NEW) { 777 if (readonly || want_cert) 778 logit("%s host key for IP address " 779 "'%.128s' not in list of known hosts.", 780 type, ip); 781 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 782 host_key, options.hash_known_hosts)) 783 logit("Failed to add the %s host key for IP " 784 "address '%.128s' to the list of known " 785 "hosts (%.500s).", type, ip, 786 user_hostfiles[0]); 787 else 788 logit("Warning: Permanently added the %s host " 789 "key for IP address '%.128s' to the list " 790 "of known hosts.", type, ip); 791 } else if (options.visual_host_key) { 792 fp = sshkey_fingerprint(host_key, 793 options.fingerprint_hash, SSH_FP_DEFAULT); 794 ra = sshkey_fingerprint(host_key, 795 options.fingerprint_hash, SSH_FP_RANDOMART); 796 if (fp == NULL || ra == NULL) 797 fatal("%s: sshkey_fingerprint fail", __func__); 798 logit("Host key fingerprint is %s\n%s", fp, ra); 799 free(ra); 800 free(fp); 801 } 802 hostkey_trusted = 1; 803 break; 804 case HOST_NEW: 805 if (options.host_key_alias == NULL && port != 0 && 806 port != SSH_DEFAULT_PORT) { 807 debug("checking without port identifier"); 808 if (check_host_key(hostname, hostaddr, 0, host_key, 809 ROQUIET, user_hostfiles, num_user_hostfiles, 810 system_hostfiles, num_system_hostfiles) == 0) { 811 debug("found matching key w/out port"); 812 break; 813 } 814 } 815 if (readonly || want_cert) 816 goto fail; 817 /* The host is new. */ 818 if (options.strict_host_key_checking == 819 SSH_STRICT_HOSTKEY_YES) { 820 /* 821 * User has requested strict host key checking. We 822 * will not add the host key automatically. The only 823 * alternative left is to abort. 824 */ 825 error("No %s host key is known for %.200s and you " 826 "have requested strict checking.", type, host); 827 goto fail; 828 } else if (options.strict_host_key_checking == 829 SSH_STRICT_HOSTKEY_ASK) { 830 char msg1[1024], msg2[1024]; 831 832 if (show_other_keys(host_hostkeys, host_key)) 833 snprintf(msg1, sizeof(msg1), 834 "\nbut keys of different type are already" 835 " known for this host."); 836 else 837 snprintf(msg1, sizeof(msg1), "."); 838 /* The default */ 839 fp = sshkey_fingerprint(host_key, 840 options.fingerprint_hash, SSH_FP_DEFAULT); 841 ra = sshkey_fingerprint(host_key, 842 options.fingerprint_hash, SSH_FP_RANDOMART); 843 if (fp == NULL || ra == NULL) 844 fatal("%s: sshkey_fingerprint fail", __func__); 845 msg2[0] = '\0'; 846 if (options.verify_host_key_dns) { 847 if (matching_host_key_dns) 848 snprintf(msg2, sizeof(msg2), 849 "Matching host key fingerprint" 850 " found in DNS.\n"); 851 else 852 snprintf(msg2, sizeof(msg2), 853 "No matching host key fingerprint" 854 " found in DNS.\n"); 855 } 856 snprintf(msg, sizeof(msg), 857 "The authenticity of host '%.200s (%s)' can't be " 858 "established%s\n" 859 "%s key fingerprint is %s.%s%s\n%s" 860 "Are you sure you want to continue connecting " 861 "(yes/no/[fingerprint])? ", 862 host, ip, msg1, type, fp, 863 options.visual_host_key ? "\n" : "", 864 options.visual_host_key ? ra : "", 865 msg2); 866 free(ra); 867 confirmed = confirm(msg, fp); 868 free(fp); 869 if (!confirmed) 870 goto fail; 871 hostkey_trusted = 1; /* user explicitly confirmed */ 872 } 873 /* 874 * If in "new" or "off" strict mode, add the key automatically 875 * to the local known_hosts file. 876 */ 877 if (options.check_host_ip && ip_status == HOST_NEW) { 878 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 879 hostp = hostline; 880 if (options.hash_known_hosts) { 881 /* Add hash of host and IP separately */ 882 r = add_host_to_hostfile(user_hostfiles[0], 883 host, host_key, options.hash_known_hosts) && 884 add_host_to_hostfile(user_hostfiles[0], ip, 885 host_key, options.hash_known_hosts); 886 } else { 887 /* Add unhashed "host,ip" */ 888 r = add_host_to_hostfile(user_hostfiles[0], 889 hostline, host_key, 890 options.hash_known_hosts); 891 } 892 } else { 893 r = add_host_to_hostfile(user_hostfiles[0], host, 894 host_key, options.hash_known_hosts); 895 hostp = host; 896 } 897 898 if (!r) 899 logit("Failed to add the host to the list of known " 900 "hosts (%.500s).", user_hostfiles[0]); 901 else 902 logit("Warning: Permanently added '%.200s' (%s) to the " 903 "list of known hosts.", hostp, type); 904 break; 905 case HOST_REVOKED: 906 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 907 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 908 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 909 error("The %s host key for %s is marked as revoked.", type, host); 910 error("This could mean that a stolen key is being used to"); 911 error("impersonate this host."); 912 913 /* 914 * If strict host key checking is in use, the user will have 915 * to edit the key manually and we can only abort. 916 */ 917 if (options.strict_host_key_checking != 918 SSH_STRICT_HOSTKEY_OFF) { 919 error("%s host key for %.200s was revoked and you have " 920 "requested strict checking.", type, host); 921 goto fail; 922 } 923 goto continue_unsafe; 924 925 case HOST_CHANGED: 926 if (want_cert) { 927 /* 928 * This is only a debug() since it is valid to have 929 * CAs with wildcard DNS matches that don't match 930 * all hosts that one might visit. 931 */ 932 debug("Host certificate authority does not " 933 "match %s in %s:%lu", CA_MARKER, 934 host_found->file, host_found->line); 935 goto fail; 936 } 937 if (readonly == ROQUIET) 938 goto fail; 939 if (options.check_host_ip && host_ip_differ) { 940 char *key_msg; 941 if (ip_status == HOST_NEW) 942 key_msg = "is unknown"; 943 else if (ip_status == HOST_OK) 944 key_msg = "is unchanged"; 945 else 946 key_msg = "has a different value"; 947 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 948 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 949 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 950 error("The %s host key for %s has changed,", type, host); 951 error("and the key for the corresponding IP address %s", ip); 952 error("%s. This could either mean that", key_msg); 953 error("DNS SPOOFING is happening or the IP address for the host"); 954 error("and its host key have changed at the same time."); 955 if (ip_status != HOST_NEW) 956 error("Offending key for IP in %s:%lu", 957 ip_found->file, ip_found->line); 958 } 959 /* The host key has changed. */ 960 warn_changed_key(host_key); 961 error("Add correct host key in %.100s to get rid of this message.", 962 user_hostfiles[0]); 963 error("Offending %s key in %s:%lu", 964 sshkey_type(host_found->key), 965 host_found->file, host_found->line); 966 967 /* 968 * If strict host key checking is in use, the user will have 969 * to edit the key manually and we can only abort. 970 */ 971 if (options.strict_host_key_checking != 972 SSH_STRICT_HOSTKEY_OFF) { 973 error("%s host key for %.200s has changed and you have " 974 "requested strict checking.", type, host); 975 goto fail; 976 } 977 978 continue_unsafe: 979 /* 980 * If strict host key checking has not been requested, allow 981 * the connection but without MITM-able authentication or 982 * forwarding. 983 */ 984 if (options.password_authentication) { 985 error("Password authentication is disabled to avoid " 986 "man-in-the-middle attacks."); 987 options.password_authentication = 0; 988 cancelled_forwarding = 1; 989 } 990 if (options.kbd_interactive_authentication) { 991 error("Keyboard-interactive authentication is disabled" 992 " to avoid man-in-the-middle attacks."); 993 options.kbd_interactive_authentication = 0; 994 options.challenge_response_authentication = 0; 995 cancelled_forwarding = 1; 996 } 997 if (options.challenge_response_authentication) { 998 error("Challenge/response authentication is disabled" 999 " to avoid man-in-the-middle attacks."); 1000 options.challenge_response_authentication = 0; 1001 cancelled_forwarding = 1; 1002 } 1003 if (options.forward_agent) { 1004 error("Agent forwarding is disabled to avoid " 1005 "man-in-the-middle attacks."); 1006 options.forward_agent = 0; 1007 cancelled_forwarding = 1; 1008 } 1009 if (options.forward_x11) { 1010 error("X11 forwarding is disabled to avoid " 1011 "man-in-the-middle attacks."); 1012 options.forward_x11 = 0; 1013 cancelled_forwarding = 1; 1014 } 1015 if (options.num_local_forwards > 0 || 1016 options.num_remote_forwards > 0) { 1017 error("Port forwarding is disabled to avoid " 1018 "man-in-the-middle attacks."); 1019 options.num_local_forwards = 1020 options.num_remote_forwards = 0; 1021 cancelled_forwarding = 1; 1022 } 1023 if (options.tun_open != SSH_TUNMODE_NO) { 1024 error("Tunnel forwarding is disabled to avoid " 1025 "man-in-the-middle attacks."); 1026 options.tun_open = SSH_TUNMODE_NO; 1027 cancelled_forwarding = 1; 1028 } 1029 if (options.exit_on_forward_failure && cancelled_forwarding) 1030 fatal("Error: forwarding disabled due to host key " 1031 "check failure"); 1032 1033 /* 1034 * XXX Should permit the user to change to use the new id. 1035 * This could be done by converting the host key to an 1036 * identifying sentence, tell that the host identifies itself 1037 * by that sentence, and ask the user if he/she wishes to 1038 * accept the authentication. 1039 */ 1040 break; 1041 case HOST_FOUND: 1042 fatal("internal error"); 1043 break; 1044 } 1045 1046 if (options.check_host_ip && host_status != HOST_CHANGED && 1047 ip_status == HOST_CHANGED) { 1048 snprintf(msg, sizeof(msg), 1049 "Warning: the %s host key for '%.200s' " 1050 "differs from the key for the IP address '%.128s'" 1051 "\nOffending key for IP in %s:%lu", 1052 type, host, ip, ip_found->file, ip_found->line); 1053 if (host_status == HOST_OK) { 1054 len = strlen(msg); 1055 snprintf(msg + len, sizeof(msg) - len, 1056 "\nMatching host key in %s:%lu", 1057 host_found->file, host_found->line); 1058 } 1059 if (options.strict_host_key_checking == 1060 SSH_STRICT_HOSTKEY_ASK) { 1061 strlcat(msg, "\nAre you sure you want " 1062 "to continue connecting (yes/no)? ", sizeof(msg)); 1063 if (!confirm(msg, NULL)) 1064 goto fail; 1065 } else if (options.strict_host_key_checking != 1066 SSH_STRICT_HOSTKEY_OFF) { 1067 logit("%s", msg); 1068 error("Exiting, you have requested strict checking."); 1069 goto fail; 1070 } else { 1071 logit("%s", msg); 1072 } 1073 } 1074 1075 if (!hostkey_trusted && options.update_hostkeys) { 1076 debug("%s: hostkey not known or explicitly trusted: " 1077 "disabling UpdateHostkeys", __func__); 1078 options.update_hostkeys = 0; 1079 } 1080 1081 free(ip); 1082 free(host); 1083 if (host_hostkeys != NULL) 1084 free_hostkeys(host_hostkeys); 1085 if (ip_hostkeys != NULL) 1086 free_hostkeys(ip_hostkeys); 1087 return 0; 1088 1089 fail: 1090 if (want_cert && host_status != HOST_REVOKED) { 1091 /* 1092 * No matching certificate. Downgrade cert to raw key and 1093 * search normally. 1094 */ 1095 debug("No matching CA found. Retry with plain key"); 1096 if ((r = sshkey_from_private(host_key, &raw_key)) != 0) 1097 fatal("%s: sshkey_from_private: %s", 1098 __func__, ssh_err(r)); 1099 if ((r = sshkey_drop_cert(raw_key)) != 0) 1100 fatal("Couldn't drop certificate: %s", ssh_err(r)); 1101 host_key = raw_key; 1102 goto retry; 1103 } 1104 sshkey_free(raw_key); 1105 free(ip); 1106 free(host); 1107 if (host_hostkeys != NULL) 1108 free_hostkeys(host_hostkeys); 1109 if (ip_hostkeys != NULL) 1110 free_hostkeys(ip_hostkeys); 1111 return -1; 1112 } 1113 1114 /* returns 0 if key verifies or -1 if key does NOT verify */ 1115 int 1116 verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key) 1117 { 1118 u_int i; 1119 int r = -1, flags = 0; 1120 char valid[64], *fp = NULL, *cafp = NULL; 1121 struct sshkey *plain = NULL; 1122 1123 if ((fp = sshkey_fingerprint(host_key, 1124 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1125 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1126 r = -1; 1127 goto out; 1128 } 1129 1130 if (sshkey_is_cert(host_key)) { 1131 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1132 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1133 error("%s: fingerprint CA key: %s", 1134 __func__, ssh_err(r)); 1135 r = -1; 1136 goto out; 1137 } 1138 sshkey_format_cert_validity(host_key->cert, 1139 valid, sizeof(valid)); 1140 debug("Server host certificate: %s %s, serial %llu " 1141 "ID \"%s\" CA %s %s valid %s", 1142 sshkey_ssh_name(host_key), fp, 1143 (unsigned long long)host_key->cert->serial, 1144 host_key->cert->key_id, 1145 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1146 valid); 1147 for (i = 0; i < host_key->cert->nprincipals; i++) { 1148 debug2("Server host certificate hostname: %s", 1149 host_key->cert->principals[i]); 1150 } 1151 } else { 1152 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp); 1153 } 1154 1155 if (sshkey_equal(previous_host_key, host_key)) { 1156 debug2("%s: server host key %s %s matches cached key", 1157 __func__, sshkey_type(host_key), fp); 1158 r = 0; 1159 goto out; 1160 } 1161 1162 /* Check in RevokedHostKeys file if specified */ 1163 if (options.revoked_host_keys != NULL) { 1164 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1165 switch (r) { 1166 case 0: 1167 break; /* not revoked */ 1168 case SSH_ERR_KEY_REVOKED: 1169 error("Host key %s %s revoked by file %s", 1170 sshkey_type(host_key), fp, 1171 options.revoked_host_keys); 1172 r = -1; 1173 goto out; 1174 default: 1175 error("Error checking host key %s %s in " 1176 "revoked keys file %s: %s", sshkey_type(host_key), 1177 fp, options.revoked_host_keys, ssh_err(r)); 1178 r = -1; 1179 goto out; 1180 } 1181 } 1182 1183 if (options.verify_host_key_dns) { 1184 /* 1185 * XXX certs are not yet supported for DNS, so downgrade 1186 * them and try the plain key. 1187 */ 1188 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1189 goto out; 1190 if (sshkey_is_cert(plain)) 1191 sshkey_drop_cert(plain); 1192 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1193 if (flags & DNS_VERIFY_FOUND) { 1194 if (options.verify_host_key_dns == 1 && 1195 flags & DNS_VERIFY_MATCH && 1196 flags & DNS_VERIFY_SECURE) { 1197 r = 0; 1198 goto out; 1199 } 1200 if (flags & DNS_VERIFY_MATCH) { 1201 matching_host_key_dns = 1; 1202 } else { 1203 warn_changed_key(plain); 1204 error("Update the SSHFP RR in DNS " 1205 "with the new host key to get rid " 1206 "of this message."); 1207 } 1208 } 1209 } 1210 } 1211 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1212 options.user_hostfiles, options.num_user_hostfiles, 1213 options.system_hostfiles, options.num_system_hostfiles); 1214 1215 out: 1216 sshkey_free(plain); 1217 free(fp); 1218 free(cafp); 1219 if (r == 0 && host_key != NULL) { 1220 sshkey_free(previous_host_key); 1221 r = sshkey_from_private(host_key, &previous_host_key); 1222 } 1223 1224 return r; 1225 } 1226 1227 /* 1228 * Starts a dialog with the server, and authenticates the current user on the 1229 * server. This does not need any extra privileges. The basic connection 1230 * to the server must already have been established before this is called. 1231 * If login fails, this function prints an error and never returns. 1232 * This function does not require super-user privileges. 1233 */ 1234 void 1235 ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost, 1236 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1237 { 1238 char *host; 1239 char *server_user, *local_user; 1240 1241 local_user = xstrdup(pw->pw_name); 1242 server_user = options.user ? options.user : local_user; 1243 1244 /* Convert the user-supplied hostname into all lowercase. */ 1245 host = xstrdup(orighost); 1246 lowercase(host); 1247 1248 /* Exchange protocol version identification strings with the server. */ 1249 if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0) 1250 cleanup_exit(255); /* error already logged */ 1251 1252 /* Put the connection into non-blocking mode. */ 1253 ssh_packet_set_nonblocking(ssh); 1254 1255 /* key exchange */ 1256 /* authenticate user */ 1257 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1258 ssh_kex2(ssh, host, hostaddr, port); 1259 ssh_userauth2(ssh, local_user, server_user, host, sensitive); 1260 free(local_user); 1261 free(host); 1262 } 1263 1264 /* print all known host keys for a given host, but skip keys of given type */ 1265 static int 1266 show_other_keys(struct hostkeys *hostkeys, struct sshkey *key) 1267 { 1268 int type[] = { 1269 KEY_RSA, 1270 KEY_DSA, 1271 KEY_ECDSA, 1272 KEY_ED25519, 1273 KEY_XMSS, 1274 -1 1275 }; 1276 int i, ret = 0; 1277 char *fp, *ra; 1278 const struct hostkey_entry *found; 1279 1280 for (i = 0; type[i] != -1; i++) { 1281 if (type[i] == key->type) 1282 continue; 1283 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1284 continue; 1285 fp = sshkey_fingerprint(found->key, 1286 options.fingerprint_hash, SSH_FP_DEFAULT); 1287 ra = sshkey_fingerprint(found->key, 1288 options.fingerprint_hash, SSH_FP_RANDOMART); 1289 if (fp == NULL || ra == NULL) 1290 fatal("%s: sshkey_fingerprint fail", __func__); 1291 logit("WARNING: %s key found for host %s\n" 1292 "in %s:%lu\n" 1293 "%s key fingerprint %s.", 1294 sshkey_type(found->key), 1295 found->host, found->file, found->line, 1296 sshkey_type(found->key), fp); 1297 if (options.visual_host_key) 1298 logit("%s", ra); 1299 free(ra); 1300 free(fp); 1301 ret = 1; 1302 } 1303 return ret; 1304 } 1305 1306 static void 1307 warn_changed_key(struct sshkey *host_key) 1308 { 1309 char *fp; 1310 1311 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1312 SSH_FP_DEFAULT); 1313 if (fp == NULL) 1314 fatal("%s: sshkey_fingerprint fail", __func__); 1315 1316 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1317 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1318 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1319 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1320 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1321 error("It is also possible that a host key has just been changed."); 1322 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1323 sshkey_type(host_key), fp); 1324 error("Please contact your system administrator."); 1325 1326 free(fp); 1327 } 1328 1329 /* 1330 * Execute a local command 1331 */ 1332 int 1333 ssh_local_cmd(const char *args) 1334 { 1335 char *shell; 1336 pid_t pid; 1337 int status; 1338 void (*osighand)(int); 1339 1340 if (!options.permit_local_command || 1341 args == NULL || !*args) 1342 return (1); 1343 1344 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1345 shell = _PATH_BSHELL; 1346 1347 osighand = signal(SIGCHLD, SIG_DFL); 1348 pid = fork(); 1349 if (pid == 0) { 1350 signal(SIGPIPE, SIG_DFL); 1351 debug3("Executing %s -c \"%s\"", shell, args); 1352 execl(shell, shell, "-c", args, (char *)NULL); 1353 error("Couldn't execute %s -c \"%s\": %s", 1354 shell, args, strerror(errno)); 1355 _exit(1); 1356 } else if (pid == -1) 1357 fatal("fork failed: %.100s", strerror(errno)); 1358 while (waitpid(pid, &status, 0) == -1) 1359 if (errno != EINTR) 1360 fatal("Couldn't wait for child: %s", strerror(errno)); 1361 signal(SIGCHLD, osighand); 1362 1363 if (!WIFEXITED(status)) 1364 return (1); 1365 1366 return (WEXITSTATUS(status)); 1367 } 1368 1369 void 1370 maybe_add_key_to_agent(char *authfile, struct sshkey *private, 1371 char *comment, char *passphrase) 1372 { 1373 int auth_sock = -1, r; 1374 const char *skprovider = NULL; 1375 1376 if (options.add_keys_to_agent == 0) 1377 return; 1378 1379 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1380 debug3("no authentication agent, not adding key"); 1381 return; 1382 } 1383 1384 if (options.add_keys_to_agent == 2 && 1385 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1386 debug3("user denied adding this key"); 1387 close(auth_sock); 1388 return; 1389 } 1390 if (sshkey_is_sk(private)) 1391 skprovider = options.sk_provider; 1392 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0, 1393 (options.add_keys_to_agent == 3), 0, skprovider)) == 0) 1394 debug("identity added to agent: %s", authfile); 1395 else 1396 debug("could not add identity to agent: %s (%d)", authfile, r); 1397 close(auth_sock); 1398 } 1399