1 /* $OpenBSD: sshconnect.c,v 1.309 2018/12/27 03:25:25 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 <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 <string.h> 35 #include <unistd.h> 36 #include <ifaddrs.h> 37 38 #include "xmalloc.h" 39 #include "ssh.h" 40 #include "sshbuf.h" 41 #include "packet.h" 42 #include "compat.h" 43 #include "sshkey.h" 44 #include "sshconnect.h" 45 #include "hostfile.h" 46 #include "log.h" 47 #include "misc.h" 48 #include "readconf.h" 49 #include "atomicio.h" 50 #include "dns.h" 51 #include "monitor_fdpass.h" 52 #include "ssh2.h" 53 #include "version.h" 54 #include "authfile.h" 55 #include "ssherr.h" 56 #include "authfd.h" 57 #include "kex.h" 58 59 struct sshkey *previous_host_key = NULL; 60 61 static int matching_host_key_dns = 0; 62 63 static pid_t proxy_command_pid = 0; 64 65 /* import */ 66 extern int debug_flag; 67 extern Options options; 68 extern char *__progname; 69 70 static int show_other_keys(struct hostkeys *, struct sshkey *); 71 static void warn_changed_key(struct sshkey *); 72 73 /* Expand a proxy command */ 74 static char * 75 expand_proxy_command(const char *proxy_command, const char *user, 76 const char *host, int port) 77 { 78 char *tmp, *ret, strport[NI_MAXSERV]; 79 80 snprintf(strport, sizeof strport, "%d", port); 81 xasprintf(&tmp, "exec %s", proxy_command); 82 ret = percent_expand(tmp, "h", host, "p", strport, 83 "r", options.user, (char *)NULL); 84 free(tmp); 85 return ret; 86 } 87 88 static void 89 stderr_null(void) 90 { 91 int devnull; 92 93 if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) { 94 error("Can't open %s for stderr redirection: %s", 95 _PATH_DEVNULL, strerror(errno)); 96 return; 97 } 98 if (devnull == STDERR_FILENO) 99 return; 100 if (dup2(devnull, STDERR_FILENO) == -1) 101 error("Cannot redirect stderr to %s", _PATH_DEVNULL); 102 if (devnull > STDERR_FILENO) 103 close(devnull); 104 } 105 106 /* 107 * Connect to the given ssh server using a proxy command that passes a 108 * a connected fd back to us. 109 */ 110 static int 111 ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port, 112 const char *proxy_command) 113 { 114 char *command_string; 115 int sp[2], sock; 116 pid_t pid; 117 char *shell; 118 119 if ((shell = getenv("SHELL")) == NULL) 120 shell = _PATH_BSHELL; 121 122 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) 123 fatal("Could not create socketpair to communicate with " 124 "proxy dialer: %.100s", strerror(errno)); 125 126 command_string = expand_proxy_command(proxy_command, options.user, 127 host, port); 128 debug("Executing proxy dialer command: %.500s", command_string); 129 130 /* Fork and execute the proxy command. */ 131 if ((pid = fork()) == 0) { 132 char *argv[10]; 133 134 close(sp[1]); 135 /* Redirect stdin and stdout. */ 136 if (sp[0] != 0) { 137 if (dup2(sp[0], 0) < 0) 138 perror("dup2 stdin"); 139 } 140 if (sp[0] != 1) { 141 if (dup2(sp[0], 1) < 0) 142 perror("dup2 stdout"); 143 } 144 if (sp[0] >= 2) 145 close(sp[0]); 146 147 /* 148 * Stderr is left for non-ControlPersist connections is so 149 * error messages may be printed on the user's terminal. 150 */ 151 if (!debug_flag && options.control_path != NULL && 152 options.control_persist) 153 stderr_null(); 154 155 argv[0] = shell; 156 argv[1] = "-c"; 157 argv[2] = command_string; 158 argv[3] = NULL; 159 160 /* 161 * Execute the proxy command. 162 * Note that we gave up any extra privileges above. 163 */ 164 execv(argv[0], argv); 165 perror(argv[0]); 166 exit(1); 167 } 168 /* Parent. */ 169 if (pid < 0) 170 fatal("fork failed: %.100s", strerror(errno)); 171 close(sp[0]); 172 free(command_string); 173 174 if ((sock = mm_receive_fd(sp[1])) == -1) 175 fatal("proxy dialer did not pass back a connection"); 176 close(sp[1]); 177 178 while (waitpid(pid, NULL, 0) == -1) 179 if (errno != EINTR) 180 fatal("Couldn't wait for child: %s", strerror(errno)); 181 182 /* Set the connection file descriptors. */ 183 if (ssh_packet_set_connection(ssh, sock, sock) == NULL) 184 return -1; /* ssh_packet_set_connection logs error */ 185 186 return 0; 187 } 188 189 /* 190 * Connect to the given ssh server using a proxy command. 191 */ 192 static int 193 ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port, 194 const char *proxy_command) 195 { 196 char *command_string; 197 int pin[2], pout[2]; 198 pid_t pid; 199 char *shell; 200 201 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 202 shell = _PATH_BSHELL; 203 204 /* Create pipes for communicating with the proxy. */ 205 if (pipe(pin) < 0 || pipe(pout) < 0) 206 fatal("Could not create pipes to communicate with the proxy: %.100s", 207 strerror(errno)); 208 209 command_string = expand_proxy_command(proxy_command, options.user, 210 host, port); 211 debug("Executing proxy command: %.500s", command_string); 212 213 /* Fork and execute the proxy command. */ 214 if ((pid = fork()) == 0) { 215 char *argv[10]; 216 217 /* Redirect stdin and stdout. */ 218 close(pin[1]); 219 if (pin[0] != 0) { 220 if (dup2(pin[0], 0) < 0) 221 perror("dup2 stdin"); 222 close(pin[0]); 223 } 224 close(pout[0]); 225 if (dup2(pout[1], 1) < 0) 226 perror("dup2 stdout"); 227 /* Cannot be 1 because pin allocated two descriptors. */ 228 close(pout[1]); 229 230 /* 231 * Stderr is left for non-ControlPersist connections is so 232 * error messages may be printed on the user's terminal. 233 */ 234 if (!debug_flag && options.control_path != NULL && 235 options.control_persist) 236 stderr_null(); 237 238 argv[0] = shell; 239 argv[1] = "-c"; 240 argv[2] = command_string; 241 argv[3] = NULL; 242 243 /* Execute the proxy command. Note that we gave up any 244 extra privileges above. */ 245 signal(SIGPIPE, SIG_DFL); 246 execv(argv[0], argv); 247 perror(argv[0]); 248 exit(1); 249 } 250 /* Parent. */ 251 if (pid < 0) 252 fatal("fork failed: %.100s", strerror(errno)); 253 else 254 proxy_command_pid = pid; /* save pid to clean up later */ 255 256 /* Close child side of the descriptors. */ 257 close(pin[0]); 258 close(pout[1]); 259 260 /* Free the command name. */ 261 free(command_string); 262 263 /* Set the connection file descriptors. */ 264 if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL) 265 return -1; /* ssh_packet_set_connection logs error */ 266 267 return 0; 268 } 269 270 void 271 ssh_kill_proxy_command(void) 272 { 273 /* 274 * Send SIGHUP to proxy command if used. We don't wait() in 275 * case it hangs and instead rely on init to reap the child 276 */ 277 if (proxy_command_pid > 1) 278 kill(proxy_command_pid, SIGHUP); 279 } 280 281 /* 282 * Search a interface address list (returned from getifaddrs(3)) for an 283 * address that matches the desired address family on the specified interface. 284 * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure. 285 */ 286 static int 287 check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs, 288 struct sockaddr_storage *resultp, socklen_t *rlenp) 289 { 290 struct sockaddr_in6 *sa6; 291 struct sockaddr_in *sa; 292 struct in6_addr *v6addr; 293 const struct ifaddrs *ifa; 294 int allow_local; 295 296 /* 297 * Prefer addresses that are not loopback or linklocal, but use them 298 * if nothing else matches. 299 */ 300 for (allow_local = 0; allow_local < 2; allow_local++) { 301 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 302 if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL || 303 (ifa->ifa_flags & IFF_UP) == 0 || 304 ifa->ifa_addr->sa_family != af || 305 strcmp(ifa->ifa_name, options.bind_interface) != 0) 306 continue; 307 switch (ifa->ifa_addr->sa_family) { 308 case AF_INET: 309 sa = (struct sockaddr_in *)ifa->ifa_addr; 310 if (!allow_local && sa->sin_addr.s_addr == 311 htonl(INADDR_LOOPBACK)) 312 continue; 313 if (*rlenp < sizeof(struct sockaddr_in)) { 314 error("%s: v4 addr doesn't fit", 315 __func__); 316 return -1; 317 } 318 *rlenp = sizeof(struct sockaddr_in); 319 memcpy(resultp, sa, *rlenp); 320 return 0; 321 case AF_INET6: 322 sa6 = (struct sockaddr_in6 *)ifa->ifa_addr; 323 v6addr = &sa6->sin6_addr; 324 if (!allow_local && 325 (IN6_IS_ADDR_LINKLOCAL(v6addr) || 326 IN6_IS_ADDR_LOOPBACK(v6addr))) 327 continue; 328 if (*rlenp < sizeof(struct sockaddr_in6)) { 329 error("%s: v6 addr doesn't fit", 330 __func__); 331 return -1; 332 } 333 *rlenp = sizeof(struct sockaddr_in6); 334 memcpy(resultp, sa6, *rlenp); 335 return 0; 336 } 337 } 338 } 339 return -1; 340 } 341 342 /* 343 * Creates a socket for use as the ssh connection. 344 */ 345 static int 346 ssh_create_socket(struct addrinfo *ai) 347 { 348 int sock, r; 349 struct sockaddr_storage bindaddr; 350 socklen_t bindaddrlen = 0; 351 struct addrinfo hints, *res = NULL; 352 struct ifaddrs *ifaddrs = NULL; 353 char ntop[NI_MAXHOST]; 354 355 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 356 if (sock < 0) { 357 error("socket: %s", strerror(errno)); 358 return -1; 359 } 360 fcntl(sock, F_SETFD, FD_CLOEXEC); 361 362 /* Bind the socket to an alternative local IP address */ 363 if (options.bind_address == NULL && options.bind_interface == NULL) 364 return sock; 365 366 if (options.bind_address != NULL) { 367 memset(&hints, 0, sizeof(hints)); 368 hints.ai_family = ai->ai_family; 369 hints.ai_socktype = ai->ai_socktype; 370 hints.ai_protocol = ai->ai_protocol; 371 hints.ai_flags = AI_PASSIVE; 372 if ((r = getaddrinfo(options.bind_address, NULL, 373 &hints, &res)) != 0) { 374 error("getaddrinfo: %s: %s", options.bind_address, 375 ssh_gai_strerror(r)); 376 goto fail; 377 } 378 if (res == NULL) { 379 error("getaddrinfo: no addrs"); 380 goto fail; 381 } 382 memcpy(&bindaddr, res->ai_addr, res->ai_addrlen); 383 bindaddrlen = res->ai_addrlen; 384 } else if (options.bind_interface != NULL) { 385 if ((r = getifaddrs(&ifaddrs)) != 0) { 386 error("getifaddrs: %s: %s", options.bind_interface, 387 strerror(errno)); 388 goto fail; 389 } 390 bindaddrlen = sizeof(bindaddr); 391 if (check_ifaddrs(options.bind_interface, ai->ai_family, 392 ifaddrs, &bindaddr, &bindaddrlen) != 0) { 393 logit("getifaddrs: %s: no suitable addresses", 394 options.bind_interface); 395 goto fail; 396 } 397 } 398 if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen, 399 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) { 400 error("%s: getnameinfo failed: %s", __func__, 401 ssh_gai_strerror(r)); 402 goto fail; 403 } 404 if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) { 405 error("bind %s: %s", ntop, strerror(errno)); 406 goto fail; 407 } 408 debug("%s: bound to %s", __func__, ntop); 409 /* success */ 410 goto out; 411 fail: 412 close(sock); 413 sock = -1; 414 out: 415 if (res != NULL) 416 freeaddrinfo(res); 417 if (ifaddrs != NULL) 418 freeifaddrs(ifaddrs); 419 return sock; 420 } 421 422 /* 423 * Opens a TCP/IP connection to the remote server on the given host. 424 * The address of the remote host will be returned in hostaddr. 425 * If port is 0, the default port will be used. 426 * Connection_attempts specifies the maximum number of tries (one per 427 * second). If proxy_command is non-NULL, it specifies the command (with %h 428 * and %p substituted for host and port, respectively) to use to contact 429 * the daemon. 430 */ 431 static int 432 ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop, 433 struct sockaddr_storage *hostaddr, u_short port, int family, 434 int connection_attempts, int *timeout_ms, int want_keepalive) 435 { 436 int on = 1; 437 int oerrno, sock = -1, attempt; 438 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 439 struct addrinfo *ai; 440 441 debug2("%s", __func__); 442 memset(ntop, 0, sizeof(ntop)); 443 memset(strport, 0, sizeof(strport)); 444 445 for (attempt = 0; attempt < connection_attempts; attempt++) { 446 if (attempt > 0) { 447 /* Sleep a moment before retrying. */ 448 sleep(1); 449 debug("Trying again..."); 450 } 451 /* 452 * Loop through addresses for this host, and try each one in 453 * sequence until the connection succeeds. 454 */ 455 for (ai = aitop; ai; ai = ai->ai_next) { 456 if (ai->ai_family != AF_INET && 457 ai->ai_family != AF_INET6) { 458 errno = EAFNOSUPPORT; 459 continue; 460 } 461 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, 462 ntop, sizeof(ntop), strport, sizeof(strport), 463 NI_NUMERICHOST|NI_NUMERICSERV) != 0) { 464 oerrno = errno; 465 error("%s: getnameinfo failed", __func__); 466 errno = oerrno; 467 continue; 468 } 469 debug("Connecting to %.200s [%.100s] port %s.", 470 host, ntop, strport); 471 472 /* Create a socket for connecting. */ 473 sock = ssh_create_socket(ai); 474 if (sock < 0) { 475 /* Any error is already output */ 476 errno = 0; 477 continue; 478 } 479 480 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, 481 timeout_ms) >= 0) { 482 /* Successful connection. */ 483 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); 484 break; 485 } else { 486 oerrno = errno; 487 debug("connect to address %s port %s: %s", 488 ntop, strport, strerror(errno)); 489 close(sock); 490 sock = -1; 491 errno = oerrno; 492 } 493 } 494 if (sock != -1) 495 break; /* Successful connection. */ 496 } 497 498 /* Return failure if we didn't get a successful connection. */ 499 if (sock == -1) { 500 error("ssh: connect to host %s port %s: %s", 501 host, strport, errno == 0 ? "failure" : strerror(errno)); 502 return -1; 503 } 504 505 debug("Connection established."); 506 507 /* Set SO_KEEPALIVE if requested. */ 508 if (want_keepalive && 509 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, 510 sizeof(on)) < 0) 511 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 512 513 /* Set the connection. */ 514 if (ssh_packet_set_connection(ssh, sock, sock) == NULL) 515 return -1; /* ssh_packet_set_connection logs error */ 516 517 return 0; 518 } 519 520 int 521 ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs, 522 struct sockaddr_storage *hostaddr, u_short port, int family, 523 int connection_attempts, int *timeout_ms, int want_keepalive) 524 { 525 if (options.proxy_command == NULL) { 526 return ssh_connect_direct(ssh, host, addrs, hostaddr, port, 527 family, connection_attempts, timeout_ms, want_keepalive); 528 } else if (strcmp(options.proxy_command, "-") == 0) { 529 if ((ssh_packet_set_connection(ssh, 530 STDIN_FILENO, STDOUT_FILENO)) == NULL) 531 return -1; /* ssh_packet_set_connection logs error */ 532 return 0; 533 } else if (options.proxy_use_fdpass) { 534 return ssh_proxy_fdpass_connect(ssh, host, port, 535 options.proxy_command); 536 } 537 return ssh_proxy_connect(ssh, host, port, options.proxy_command); 538 } 539 540 /* defaults to 'no' */ 541 static int 542 confirm(const char *prompt) 543 { 544 const char *msg, *again = "Please type 'yes' or 'no': "; 545 char *p; 546 int ret = -1; 547 548 if (options.batch_mode) 549 return 0; 550 for (msg = prompt;;msg = again) { 551 p = read_passphrase(msg, RP_ECHO); 552 if (p == NULL) 553 return 0; 554 p[strcspn(p, "\n")] = '\0'; 555 if (p[0] == '\0' || strcasecmp(p, "no") == 0) 556 ret = 0; 557 else if (strcasecmp(p, "yes") == 0) 558 ret = 1; 559 free(p); 560 if (ret != -1) 561 return ret; 562 } 563 } 564 565 static int 566 check_host_cert(const char *host, const struct sshkey *key) 567 { 568 const char *reason; 569 int r; 570 571 if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) { 572 error("%s", reason); 573 return 0; 574 } 575 if (sshbuf_len(key->cert->critical) != 0) { 576 error("Certificate for %s contains unsupported " 577 "critical options(s)", host); 578 return 0; 579 } 580 if ((r = sshkey_check_cert_sigtype(key, 581 options.ca_sign_algorithms)) != 0) { 582 logit("%s: certificate signature algorithm %s: %s", __func__, 583 (key->cert == NULL || key->cert->signature_type == NULL) ? 584 "(null)" : key->cert->signature_type, ssh_err(r)); 585 return 0; 586 } 587 588 return 1; 589 } 590 591 static int 592 sockaddr_is_local(struct sockaddr *hostaddr) 593 { 594 switch (hostaddr->sa_family) { 595 case AF_INET: 596 return (ntohl(((struct sockaddr_in *)hostaddr)-> 597 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 598 case AF_INET6: 599 return IN6_IS_ADDR_LOOPBACK( 600 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 601 default: 602 return 0; 603 } 604 } 605 606 /* 607 * Prepare the hostname and ip address strings that are used to lookup 608 * host keys in known_hosts files. These may have a port number appended. 609 */ 610 void 611 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 612 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 613 { 614 char ntop[NI_MAXHOST]; 615 616 /* 617 * We don't have the remote ip-address for connections 618 * using a proxy command 619 */ 620 if (hostfile_ipaddr != NULL) { 621 if (options.proxy_command == NULL) { 622 if (getnameinfo(hostaddr, hostaddr->sa_len, 623 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 624 fatal("%s: getnameinfo failed", __func__); 625 *hostfile_ipaddr = put_host_port(ntop, port); 626 } else { 627 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 628 "command>"); 629 } 630 } 631 632 /* 633 * Allow the user to record the key under a different name or 634 * differentiate a non-standard port. This is useful for ssh 635 * tunneling over forwarded connections or if you run multiple 636 * sshd's on different ports on the same machine. 637 */ 638 if (hostfile_hostname != NULL) { 639 if (options.host_key_alias != NULL) { 640 *hostfile_hostname = xstrdup(options.host_key_alias); 641 debug("using hostkeyalias: %s", *hostfile_hostname); 642 } else { 643 *hostfile_hostname = put_host_port(hostname, port); 644 } 645 } 646 } 647 648 /* 649 * check whether the supplied host key is valid, return -1 if the key 650 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 651 */ 652 #define RDRW 0 653 #define RDONLY 1 654 #define ROQUIET 2 655 static int 656 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 657 struct sshkey *host_key, int readonly, 658 char **user_hostfiles, u_int num_user_hostfiles, 659 char **system_hostfiles, u_int num_system_hostfiles) 660 { 661 HostStatus host_status; 662 HostStatus ip_status; 663 struct sshkey *raw_key = NULL; 664 char *ip = NULL, *host = NULL; 665 char hostline[1000], *hostp, *fp, *ra; 666 char msg[1024]; 667 const char *type; 668 const struct hostkey_entry *host_found, *ip_found; 669 int len, cancelled_forwarding = 0; 670 int local = sockaddr_is_local(hostaddr); 671 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0; 672 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 673 struct hostkeys *host_hostkeys, *ip_hostkeys; 674 u_int i; 675 676 /* 677 * Force accepting of the host key for loopback/localhost. The 678 * problem is that if the home directory is NFS-mounted to multiple 679 * machines, localhost will refer to a different machine in each of 680 * them, and the user will get bogus HOST_CHANGED warnings. This 681 * essentially disables host authentication for localhost; however, 682 * this is probably not a real problem. 683 */ 684 if (options.no_host_authentication_for_localhost == 1 && local && 685 options.host_key_alias == NULL) { 686 debug("Forcing accepting of host key for " 687 "loopback/localhost."); 688 return 0; 689 } 690 691 /* 692 * Prepare the hostname and address strings used for hostkey lookup. 693 * In some cases, these will have a port number appended. 694 */ 695 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 696 697 /* 698 * Turn off check_host_ip if the connection is to localhost, via proxy 699 * command or if we don't have a hostname to compare with 700 */ 701 if (options.check_host_ip && (local || 702 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 703 options.check_host_ip = 0; 704 705 host_hostkeys = init_hostkeys(); 706 for (i = 0; i < num_user_hostfiles; i++) 707 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 708 for (i = 0; i < num_system_hostfiles; i++) 709 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 710 711 ip_hostkeys = NULL; 712 if (!want_cert && options.check_host_ip) { 713 ip_hostkeys = init_hostkeys(); 714 for (i = 0; i < num_user_hostfiles; i++) 715 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 716 for (i = 0; i < num_system_hostfiles; i++) 717 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 718 } 719 720 retry: 721 /* Reload these as they may have changed on cert->key downgrade */ 722 want_cert = sshkey_is_cert(host_key); 723 type = sshkey_type(host_key); 724 725 /* 726 * Check if the host key is present in the user's list of known 727 * hosts or in the systemwide list. 728 */ 729 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 730 &host_found); 731 732 /* 733 * Also perform check for the ip address, skip the check if we are 734 * localhost, looking for a certificate, or the hostname was an ip 735 * address to begin with. 736 */ 737 if (!want_cert && ip_hostkeys != NULL) { 738 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 739 &ip_found); 740 if (host_status == HOST_CHANGED && 741 (ip_status != HOST_CHANGED || 742 (ip_found != NULL && 743 !sshkey_equal(ip_found->key, host_found->key)))) 744 host_ip_differ = 1; 745 } else 746 ip_status = host_status; 747 748 switch (host_status) { 749 case HOST_OK: 750 /* The host is known and the key matches. */ 751 debug("Host '%.200s' is known and matches the %s host %s.", 752 host, type, want_cert ? "certificate" : "key"); 753 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 754 host_found->file, host_found->line); 755 if (want_cert && 756 !check_host_cert(options.host_key_alias == NULL ? 757 hostname : options.host_key_alias, host_key)) 758 goto fail; 759 if (options.check_host_ip && ip_status == HOST_NEW) { 760 if (readonly || want_cert) 761 logit("%s host key for IP address " 762 "'%.128s' not in list of known hosts.", 763 type, ip); 764 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 765 host_key, options.hash_known_hosts)) 766 logit("Failed to add the %s host key for IP " 767 "address '%.128s' to the list of known " 768 "hosts (%.500s).", type, ip, 769 user_hostfiles[0]); 770 else 771 logit("Warning: Permanently added the %s host " 772 "key for IP address '%.128s' to the list " 773 "of known hosts.", type, ip); 774 } else if (options.visual_host_key) { 775 fp = sshkey_fingerprint(host_key, 776 options.fingerprint_hash, SSH_FP_DEFAULT); 777 ra = sshkey_fingerprint(host_key, 778 options.fingerprint_hash, SSH_FP_RANDOMART); 779 if (fp == NULL || ra == NULL) 780 fatal("%s: sshkey_fingerprint fail", __func__); 781 logit("Host key fingerprint is %s\n%s", fp, ra); 782 free(ra); 783 free(fp); 784 } 785 hostkey_trusted = 1; 786 break; 787 case HOST_NEW: 788 if (options.host_key_alias == NULL && port != 0 && 789 port != SSH_DEFAULT_PORT) { 790 debug("checking without port identifier"); 791 if (check_host_key(hostname, hostaddr, 0, host_key, 792 ROQUIET, user_hostfiles, num_user_hostfiles, 793 system_hostfiles, num_system_hostfiles) == 0) { 794 debug("found matching key w/out port"); 795 break; 796 } 797 } 798 if (readonly || want_cert) 799 goto fail; 800 /* The host is new. */ 801 if (options.strict_host_key_checking == 802 SSH_STRICT_HOSTKEY_YES) { 803 /* 804 * User has requested strict host key checking. We 805 * will not add the host key automatically. The only 806 * alternative left is to abort. 807 */ 808 error("No %s host key is known for %.200s and you " 809 "have requested strict checking.", type, host); 810 goto fail; 811 } else if (options.strict_host_key_checking == 812 SSH_STRICT_HOSTKEY_ASK) { 813 char msg1[1024], msg2[1024]; 814 815 if (show_other_keys(host_hostkeys, host_key)) 816 snprintf(msg1, sizeof(msg1), 817 "\nbut keys of different type are already" 818 " known for this host."); 819 else 820 snprintf(msg1, sizeof(msg1), "."); 821 /* The default */ 822 fp = sshkey_fingerprint(host_key, 823 options.fingerprint_hash, SSH_FP_DEFAULT); 824 ra = sshkey_fingerprint(host_key, 825 options.fingerprint_hash, SSH_FP_RANDOMART); 826 if (fp == NULL || ra == NULL) 827 fatal("%s: sshkey_fingerprint fail", __func__); 828 msg2[0] = '\0'; 829 if (options.verify_host_key_dns) { 830 if (matching_host_key_dns) 831 snprintf(msg2, sizeof(msg2), 832 "Matching host key fingerprint" 833 " found in DNS.\n"); 834 else 835 snprintf(msg2, sizeof(msg2), 836 "No matching host key fingerprint" 837 " found in DNS.\n"); 838 } 839 snprintf(msg, sizeof(msg), 840 "The authenticity of host '%.200s (%s)' can't be " 841 "established%s\n" 842 "%s key fingerprint is %s.%s%s\n%s" 843 "Are you sure you want to continue connecting " 844 "(yes/no)? ", 845 host, ip, msg1, type, fp, 846 options.visual_host_key ? "\n" : "", 847 options.visual_host_key ? ra : "", 848 msg2); 849 free(ra); 850 free(fp); 851 if (!confirm(msg)) 852 goto fail; 853 hostkey_trusted = 1; /* user explicitly confirmed */ 854 } 855 /* 856 * If in "new" or "off" strict mode, add the key automatically 857 * to the local known_hosts file. 858 */ 859 if (options.check_host_ip && ip_status == HOST_NEW) { 860 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 861 hostp = hostline; 862 if (options.hash_known_hosts) { 863 /* Add hash of host and IP separately */ 864 r = add_host_to_hostfile(user_hostfiles[0], 865 host, host_key, options.hash_known_hosts) && 866 add_host_to_hostfile(user_hostfiles[0], ip, 867 host_key, options.hash_known_hosts); 868 } else { 869 /* Add unhashed "host,ip" */ 870 r = add_host_to_hostfile(user_hostfiles[0], 871 hostline, host_key, 872 options.hash_known_hosts); 873 } 874 } else { 875 r = add_host_to_hostfile(user_hostfiles[0], host, 876 host_key, options.hash_known_hosts); 877 hostp = host; 878 } 879 880 if (!r) 881 logit("Failed to add the host to the list of known " 882 "hosts (%.500s).", user_hostfiles[0]); 883 else 884 logit("Warning: Permanently added '%.200s' (%s) to the " 885 "list of known hosts.", hostp, type); 886 break; 887 case HOST_REVOKED: 888 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 889 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 890 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 891 error("The %s host key for %s is marked as revoked.", type, host); 892 error("This could mean that a stolen key is being used to"); 893 error("impersonate this host."); 894 895 /* 896 * If strict host key checking is in use, the user will have 897 * to edit the key manually and we can only abort. 898 */ 899 if (options.strict_host_key_checking != 900 SSH_STRICT_HOSTKEY_OFF) { 901 error("%s host key for %.200s was revoked and you have " 902 "requested strict checking.", type, host); 903 goto fail; 904 } 905 goto continue_unsafe; 906 907 case HOST_CHANGED: 908 if (want_cert) { 909 /* 910 * This is only a debug() since it is valid to have 911 * CAs with wildcard DNS matches that don't match 912 * all hosts that one might visit. 913 */ 914 debug("Host certificate authority does not " 915 "match %s in %s:%lu", CA_MARKER, 916 host_found->file, host_found->line); 917 goto fail; 918 } 919 if (readonly == ROQUIET) 920 goto fail; 921 if (options.check_host_ip && host_ip_differ) { 922 char *key_msg; 923 if (ip_status == HOST_NEW) 924 key_msg = "is unknown"; 925 else if (ip_status == HOST_OK) 926 key_msg = "is unchanged"; 927 else 928 key_msg = "has a different value"; 929 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 930 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 931 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 932 error("The %s host key for %s has changed,", type, host); 933 error("and the key for the corresponding IP address %s", ip); 934 error("%s. This could either mean that", key_msg); 935 error("DNS SPOOFING is happening or the IP address for the host"); 936 error("and its host key have changed at the same time."); 937 if (ip_status != HOST_NEW) 938 error("Offending key for IP in %s:%lu", 939 ip_found->file, ip_found->line); 940 } 941 /* The host key has changed. */ 942 warn_changed_key(host_key); 943 error("Add correct host key in %.100s to get rid of this message.", 944 user_hostfiles[0]); 945 error("Offending %s key in %s:%lu", 946 sshkey_type(host_found->key), 947 host_found->file, host_found->line); 948 949 /* 950 * If strict host key checking is in use, the user will have 951 * to edit the key manually and we can only abort. 952 */ 953 if (options.strict_host_key_checking != 954 SSH_STRICT_HOSTKEY_OFF) { 955 error("%s host key for %.200s has changed and you have " 956 "requested strict checking.", type, host); 957 goto fail; 958 } 959 960 continue_unsafe: 961 /* 962 * If strict host key checking has not been requested, allow 963 * the connection but without MITM-able authentication or 964 * forwarding. 965 */ 966 if (options.password_authentication) { 967 error("Password authentication is disabled to avoid " 968 "man-in-the-middle attacks."); 969 options.password_authentication = 0; 970 cancelled_forwarding = 1; 971 } 972 if (options.kbd_interactive_authentication) { 973 error("Keyboard-interactive authentication is disabled" 974 " to avoid man-in-the-middle attacks."); 975 options.kbd_interactive_authentication = 0; 976 options.challenge_response_authentication = 0; 977 cancelled_forwarding = 1; 978 } 979 if (options.challenge_response_authentication) { 980 error("Challenge/response authentication is disabled" 981 " to avoid man-in-the-middle attacks."); 982 options.challenge_response_authentication = 0; 983 cancelled_forwarding = 1; 984 } 985 if (options.forward_agent) { 986 error("Agent forwarding is disabled to avoid " 987 "man-in-the-middle attacks."); 988 options.forward_agent = 0; 989 cancelled_forwarding = 1; 990 } 991 if (options.forward_x11) { 992 error("X11 forwarding is disabled to avoid " 993 "man-in-the-middle attacks."); 994 options.forward_x11 = 0; 995 cancelled_forwarding = 1; 996 } 997 if (options.num_local_forwards > 0 || 998 options.num_remote_forwards > 0) { 999 error("Port forwarding is disabled to avoid " 1000 "man-in-the-middle attacks."); 1001 options.num_local_forwards = 1002 options.num_remote_forwards = 0; 1003 cancelled_forwarding = 1; 1004 } 1005 if (options.tun_open != SSH_TUNMODE_NO) { 1006 error("Tunnel forwarding is disabled to avoid " 1007 "man-in-the-middle attacks."); 1008 options.tun_open = SSH_TUNMODE_NO; 1009 cancelled_forwarding = 1; 1010 } 1011 if (options.exit_on_forward_failure && cancelled_forwarding) 1012 fatal("Error: forwarding disabled due to host key " 1013 "check failure"); 1014 1015 /* 1016 * XXX Should permit the user to change to use the new id. 1017 * This could be done by converting the host key to an 1018 * identifying sentence, tell that the host identifies itself 1019 * by that sentence, and ask the user if he/she wishes to 1020 * accept the authentication. 1021 */ 1022 break; 1023 case HOST_FOUND: 1024 fatal("internal error"); 1025 break; 1026 } 1027 1028 if (options.check_host_ip && host_status != HOST_CHANGED && 1029 ip_status == HOST_CHANGED) { 1030 snprintf(msg, sizeof(msg), 1031 "Warning: the %s host key for '%.200s' " 1032 "differs from the key for the IP address '%.128s'" 1033 "\nOffending key for IP in %s:%lu", 1034 type, host, ip, ip_found->file, ip_found->line); 1035 if (host_status == HOST_OK) { 1036 len = strlen(msg); 1037 snprintf(msg + len, sizeof(msg) - len, 1038 "\nMatching host key in %s:%lu", 1039 host_found->file, host_found->line); 1040 } 1041 if (options.strict_host_key_checking == 1042 SSH_STRICT_HOSTKEY_ASK) { 1043 strlcat(msg, "\nAre you sure you want " 1044 "to continue connecting (yes/no)? ", sizeof(msg)); 1045 if (!confirm(msg)) 1046 goto fail; 1047 } else if (options.strict_host_key_checking != 1048 SSH_STRICT_HOSTKEY_OFF) { 1049 logit("%s", msg); 1050 error("Exiting, you have requested strict checking."); 1051 goto fail; 1052 } else { 1053 logit("%s", msg); 1054 } 1055 } 1056 1057 if (!hostkey_trusted && options.update_hostkeys) { 1058 debug("%s: hostkey not known or explicitly trusted: " 1059 "disabling UpdateHostkeys", __func__); 1060 options.update_hostkeys = 0; 1061 } 1062 1063 free(ip); 1064 free(host); 1065 if (host_hostkeys != NULL) 1066 free_hostkeys(host_hostkeys); 1067 if (ip_hostkeys != NULL) 1068 free_hostkeys(ip_hostkeys); 1069 return 0; 1070 1071 fail: 1072 if (want_cert && host_status != HOST_REVOKED) { 1073 /* 1074 * No matching certificate. Downgrade cert to raw key and 1075 * search normally. 1076 */ 1077 debug("No matching CA found. Retry with plain key"); 1078 if ((r = sshkey_from_private(host_key, &raw_key)) != 0) 1079 fatal("%s: sshkey_from_private: %s", 1080 __func__, ssh_err(r)); 1081 if ((r = sshkey_drop_cert(raw_key)) != 0) 1082 fatal("Couldn't drop certificate: %s", ssh_err(r)); 1083 host_key = raw_key; 1084 goto retry; 1085 } 1086 sshkey_free(raw_key); 1087 free(ip); 1088 free(host); 1089 if (host_hostkeys != NULL) 1090 free_hostkeys(host_hostkeys); 1091 if (ip_hostkeys != NULL) 1092 free_hostkeys(ip_hostkeys); 1093 return -1; 1094 } 1095 1096 /* returns 0 if key verifies or -1 if key does NOT verify */ 1097 int 1098 verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key) 1099 { 1100 u_int i; 1101 int r = -1, flags = 0; 1102 char valid[64], *fp = NULL, *cafp = NULL; 1103 struct sshkey *plain = NULL; 1104 1105 if ((fp = sshkey_fingerprint(host_key, 1106 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1107 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1108 r = -1; 1109 goto out; 1110 } 1111 1112 if (sshkey_is_cert(host_key)) { 1113 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1114 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1115 error("%s: fingerprint CA key: %s", 1116 __func__, ssh_err(r)); 1117 r = -1; 1118 goto out; 1119 } 1120 sshkey_format_cert_validity(host_key->cert, 1121 valid, sizeof(valid)); 1122 debug("Server host certificate: %s %s, serial %llu " 1123 "ID \"%s\" CA %s %s valid %s", 1124 sshkey_ssh_name(host_key), fp, 1125 (unsigned long long)host_key->cert->serial, 1126 host_key->cert->key_id, 1127 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1128 valid); 1129 for (i = 0; i < host_key->cert->nprincipals; i++) { 1130 debug2("Server host certificate hostname: %s", 1131 host_key->cert->principals[i]); 1132 } 1133 } else { 1134 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp); 1135 } 1136 1137 if (sshkey_equal(previous_host_key, host_key)) { 1138 debug2("%s: server host key %s %s matches cached key", 1139 __func__, sshkey_type(host_key), fp); 1140 r = 0; 1141 goto out; 1142 } 1143 1144 /* Check in RevokedHostKeys file if specified */ 1145 if (options.revoked_host_keys != NULL) { 1146 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1147 switch (r) { 1148 case 0: 1149 break; /* not revoked */ 1150 case SSH_ERR_KEY_REVOKED: 1151 error("Host key %s %s revoked by file %s", 1152 sshkey_type(host_key), fp, 1153 options.revoked_host_keys); 1154 r = -1; 1155 goto out; 1156 default: 1157 error("Error checking host key %s %s in " 1158 "revoked keys file %s: %s", sshkey_type(host_key), 1159 fp, options.revoked_host_keys, ssh_err(r)); 1160 r = -1; 1161 goto out; 1162 } 1163 } 1164 1165 if (options.verify_host_key_dns) { 1166 /* 1167 * XXX certs are not yet supported for DNS, so downgrade 1168 * them and try the plain key. 1169 */ 1170 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1171 goto out; 1172 if (sshkey_is_cert(plain)) 1173 sshkey_drop_cert(plain); 1174 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1175 if (flags & DNS_VERIFY_FOUND) { 1176 if (options.verify_host_key_dns == 1 && 1177 flags & DNS_VERIFY_MATCH && 1178 flags & DNS_VERIFY_SECURE) { 1179 r = 0; 1180 goto out; 1181 } 1182 if (flags & DNS_VERIFY_MATCH) { 1183 matching_host_key_dns = 1; 1184 } else { 1185 warn_changed_key(plain); 1186 error("Update the SSHFP RR in DNS " 1187 "with the new host key to get rid " 1188 "of this message."); 1189 } 1190 } 1191 } 1192 } 1193 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1194 options.user_hostfiles, options.num_user_hostfiles, 1195 options.system_hostfiles, options.num_system_hostfiles); 1196 1197 out: 1198 sshkey_free(plain); 1199 free(fp); 1200 free(cafp); 1201 if (r == 0 && host_key != NULL) { 1202 sshkey_free(previous_host_key); 1203 r = sshkey_from_private(host_key, &previous_host_key); 1204 } 1205 1206 return r; 1207 } 1208 1209 /* 1210 * Starts a dialog with the server, and authenticates the current user on the 1211 * server. This does not need any extra privileges. The basic connection 1212 * to the server must already have been established before this is called. 1213 * If login fails, this function prints an error and never returns. 1214 * This function does not require super-user privileges. 1215 */ 1216 void 1217 ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost, 1218 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1219 { 1220 char *host; 1221 char *server_user, *local_user; 1222 1223 local_user = xstrdup(pw->pw_name); 1224 server_user = options.user ? options.user : local_user; 1225 1226 /* Convert the user-supplied hostname into all lowercase. */ 1227 host = xstrdup(orighost); 1228 lowercase(host); 1229 1230 /* Exchange protocol version identification strings with the server. */ 1231 if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0) 1232 cleanup_exit(255); /* error already logged */ 1233 1234 /* Put the connection into non-blocking mode. */ 1235 ssh_packet_set_nonblocking(ssh); 1236 1237 /* key exchange */ 1238 /* authenticate user */ 1239 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1240 ssh_kex2(ssh, host, hostaddr, port); 1241 ssh_userauth2(ssh, local_user, server_user, host, sensitive); 1242 free(local_user); 1243 } 1244 1245 void 1246 ssh_put_password(char *password) 1247 { 1248 int size; 1249 char *padded; 1250 1251 if (datafellows & SSH_BUG_PASSWORDPAD) { 1252 packet_put_cstring(password); 1253 return; 1254 } 1255 size = ROUNDUP(strlen(password) + 1, 32); 1256 padded = xcalloc(1, size); 1257 strlcpy(padded, password, size); 1258 packet_put_string(padded, size); 1259 explicit_bzero(padded, size); 1260 free(padded); 1261 } 1262 1263 /* print all known host keys for a given host, but skip keys of given type */ 1264 static int 1265 show_other_keys(struct hostkeys *hostkeys, struct sshkey *key) 1266 { 1267 int type[] = { 1268 KEY_RSA, 1269 KEY_DSA, 1270 KEY_ECDSA, 1271 KEY_ED25519, 1272 KEY_XMSS, 1273 -1 1274 }; 1275 int i, ret = 0; 1276 char *fp, *ra; 1277 const struct hostkey_entry *found; 1278 1279 for (i = 0; type[i] != -1; i++) { 1280 if (type[i] == key->type) 1281 continue; 1282 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1283 continue; 1284 fp = sshkey_fingerprint(found->key, 1285 options.fingerprint_hash, SSH_FP_DEFAULT); 1286 ra = sshkey_fingerprint(found->key, 1287 options.fingerprint_hash, SSH_FP_RANDOMART); 1288 if (fp == NULL || ra == NULL) 1289 fatal("%s: sshkey_fingerprint fail", __func__); 1290 logit("WARNING: %s key found for host %s\n" 1291 "in %s:%lu\n" 1292 "%s key fingerprint %s.", 1293 sshkey_type(found->key), 1294 found->host, found->file, found->line, 1295 sshkey_type(found->key), fp); 1296 if (options.visual_host_key) 1297 logit("%s", ra); 1298 free(ra); 1299 free(fp); 1300 ret = 1; 1301 } 1302 return ret; 1303 } 1304 1305 static void 1306 warn_changed_key(struct sshkey *host_key) 1307 { 1308 char *fp; 1309 1310 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1311 SSH_FP_DEFAULT); 1312 if (fp == NULL) 1313 fatal("%s: sshkey_fingerprint fail", __func__); 1314 1315 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1316 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1317 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1318 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1319 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1320 error("It is also possible that a host key has just been changed."); 1321 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1322 sshkey_type(host_key), fp); 1323 error("Please contact your system administrator."); 1324 1325 free(fp); 1326 } 1327 1328 /* 1329 * Execute a local command 1330 */ 1331 int 1332 ssh_local_cmd(const char *args) 1333 { 1334 char *shell; 1335 pid_t pid; 1336 int status; 1337 void (*osighand)(int); 1338 1339 if (!options.permit_local_command || 1340 args == NULL || !*args) 1341 return (1); 1342 1343 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1344 shell = _PATH_BSHELL; 1345 1346 osighand = signal(SIGCHLD, SIG_DFL); 1347 pid = fork(); 1348 if (pid == 0) { 1349 signal(SIGPIPE, SIG_DFL); 1350 debug3("Executing %s -c \"%s\"", shell, args); 1351 execl(shell, shell, "-c", args, (char *)NULL); 1352 error("Couldn't execute %s -c \"%s\": %s", 1353 shell, args, strerror(errno)); 1354 _exit(1); 1355 } else if (pid == -1) 1356 fatal("fork failed: %.100s", strerror(errno)); 1357 while (waitpid(pid, &status, 0) == -1) 1358 if (errno != EINTR) 1359 fatal("Couldn't wait for child: %s", strerror(errno)); 1360 signal(SIGCHLD, osighand); 1361 1362 if (!WIFEXITED(status)) 1363 return (1); 1364 1365 return (WEXITSTATUS(status)); 1366 } 1367 1368 void 1369 maybe_add_key_to_agent(char *authfile, const struct sshkey *private, 1370 char *comment, char *passphrase) 1371 { 1372 int auth_sock = -1, r; 1373 1374 if (options.add_keys_to_agent == 0) 1375 return; 1376 1377 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1378 debug3("no authentication agent, not adding key"); 1379 return; 1380 } 1381 1382 if (options.add_keys_to_agent == 2 && 1383 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1384 debug3("user denied adding this key"); 1385 close(auth_sock); 1386 return; 1387 } 1388 1389 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0, 1390 (options.add_keys_to_agent == 3), 0)) == 0) 1391 debug("identity added to agent: %s", authfile); 1392 else 1393 debug("could not add identity to agent: %s (%d)", authfile, r); 1394 close(auth_sock); 1395 } 1396