1 /* $OpenBSD: sshconnect.c,v 1.328 2020/01/25 07:17:18 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 <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, host_arg, 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, host_arg, 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 ssh_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, *cp; 562 int ret = -1; 563 564 if (options.batch_mode) 565 return 0; 566 for (msg = prompt;;msg = fingerprint ? again_fp : again) { 567 cp = p = read_passphrase(msg, RP_ECHO); 568 if (p == NULL) 569 return 0; 570 p += strspn(p, " \t"); /* skip leading whitespace */ 571 p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */ 572 if (p[0] == '\0' || strcasecmp(p, "no") == 0) 573 ret = 0; 574 else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL && 575 strcasecmp(p, fingerprint) == 0)) 576 ret = 1; 577 free(cp); 578 if (ret != -1) 579 return ret; 580 } 581 } 582 583 static int 584 check_host_cert(const char *host, const struct sshkey *key) 585 { 586 const char *reason; 587 int r; 588 589 if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) { 590 error("%s", reason); 591 return 0; 592 } 593 if (sshbuf_len(key->cert->critical) != 0) { 594 error("Certificate for %s contains unsupported " 595 "critical options(s)", host); 596 return 0; 597 } 598 if ((r = sshkey_check_cert_sigtype(key, 599 options.ca_sign_algorithms)) != 0) { 600 logit("%s: certificate signature algorithm %s: %s", __func__, 601 (key->cert == NULL || key->cert->signature_type == NULL) ? 602 "(null)" : key->cert->signature_type, ssh_err(r)); 603 return 0; 604 } 605 606 return 1; 607 } 608 609 static int 610 sockaddr_is_local(struct sockaddr *hostaddr) 611 { 612 switch (hostaddr->sa_family) { 613 case AF_INET: 614 return (ntohl(((struct sockaddr_in *)hostaddr)-> 615 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; 616 case AF_INET6: 617 return IN6_IS_ADDR_LOOPBACK( 618 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); 619 default: 620 return 0; 621 } 622 } 623 624 /* 625 * Prepare the hostname and ip address strings that are used to lookup 626 * host keys in known_hosts files. These may have a port number appended. 627 */ 628 void 629 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, 630 u_short port, char **hostfile_hostname, char **hostfile_ipaddr) 631 { 632 char ntop[NI_MAXHOST]; 633 634 /* 635 * We don't have the remote ip-address for connections 636 * using a proxy command 637 */ 638 if (hostfile_ipaddr != NULL) { 639 if (options.proxy_command == NULL) { 640 if (getnameinfo(hostaddr, hostaddr->sa_len, 641 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) 642 fatal("%s: getnameinfo failed", __func__); 643 *hostfile_ipaddr = put_host_port(ntop, port); 644 } else { 645 *hostfile_ipaddr = xstrdup("<no hostip for proxy " 646 "command>"); 647 } 648 } 649 650 /* 651 * Allow the user to record the key under a different name or 652 * differentiate a non-standard port. This is useful for ssh 653 * tunneling over forwarded connections or if you run multiple 654 * sshd's on different ports on the same machine. 655 */ 656 if (hostfile_hostname != NULL) { 657 if (options.host_key_alias != NULL) { 658 *hostfile_hostname = xstrdup(options.host_key_alias); 659 debug("using hostkeyalias: %s", *hostfile_hostname); 660 } else { 661 *hostfile_hostname = put_host_port(hostname, port); 662 } 663 } 664 } 665 666 /* 667 * check whether the supplied host key is valid, return -1 if the key 668 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. 669 */ 670 #define RDRW 0 671 #define RDONLY 1 672 #define ROQUIET 2 673 static int 674 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, 675 struct sshkey *host_key, int readonly, 676 char **user_hostfiles, u_int num_user_hostfiles, 677 char **system_hostfiles, u_int num_system_hostfiles) 678 { 679 HostStatus host_status; 680 HostStatus ip_status; 681 struct sshkey *raw_key = NULL; 682 char *ip = NULL, *host = NULL; 683 char hostline[1000], *hostp, *fp, *ra; 684 char msg[1024]; 685 const char *type; 686 const struct hostkey_entry *host_found, *ip_found; 687 int len, cancelled_forwarding = 0, confirmed; 688 int local = sockaddr_is_local(hostaddr); 689 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0; 690 int hostkey_trusted = 0; /* Known or explicitly accepted by user */ 691 struct hostkeys *host_hostkeys, *ip_hostkeys; 692 u_int i; 693 694 /* 695 * Force accepting of the host key for loopback/localhost. The 696 * problem is that if the home directory is NFS-mounted to multiple 697 * machines, localhost will refer to a different machine in each of 698 * them, and the user will get bogus HOST_CHANGED warnings. This 699 * essentially disables host authentication for localhost; however, 700 * this is probably not a real problem. 701 */ 702 if (options.no_host_authentication_for_localhost == 1 && local && 703 options.host_key_alias == NULL) { 704 debug("Forcing accepting of host key for " 705 "loopback/localhost."); 706 return 0; 707 } 708 709 /* 710 * Prepare the hostname and address strings used for hostkey lookup. 711 * In some cases, these will have a port number appended. 712 */ 713 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip); 714 715 /* 716 * Turn off check_host_ip if the connection is to localhost, via proxy 717 * command or if we don't have a hostname to compare with 718 */ 719 if (options.check_host_ip && (local || 720 strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) 721 options.check_host_ip = 0; 722 723 host_hostkeys = init_hostkeys(); 724 for (i = 0; i < num_user_hostfiles; i++) 725 load_hostkeys(host_hostkeys, host, user_hostfiles[i]); 726 for (i = 0; i < num_system_hostfiles; i++) 727 load_hostkeys(host_hostkeys, host, system_hostfiles[i]); 728 729 ip_hostkeys = NULL; 730 if (!want_cert && options.check_host_ip) { 731 ip_hostkeys = init_hostkeys(); 732 for (i = 0; i < num_user_hostfiles; i++) 733 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]); 734 for (i = 0; i < num_system_hostfiles; i++) 735 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]); 736 } 737 738 retry: 739 /* Reload these as they may have changed on cert->key downgrade */ 740 want_cert = sshkey_is_cert(host_key); 741 type = sshkey_type(host_key); 742 743 /* 744 * Check if the host key is present in the user's list of known 745 * hosts or in the systemwide list. 746 */ 747 host_status = check_key_in_hostkeys(host_hostkeys, host_key, 748 &host_found); 749 750 /* 751 * Also perform check for the ip address, skip the check if we are 752 * localhost, looking for a certificate, or the hostname was an ip 753 * address to begin with. 754 */ 755 if (!want_cert && ip_hostkeys != NULL) { 756 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, 757 &ip_found); 758 if (host_status == HOST_CHANGED && 759 (ip_status != HOST_CHANGED || 760 (ip_found != NULL && 761 !sshkey_equal(ip_found->key, host_found->key)))) 762 host_ip_differ = 1; 763 } else 764 ip_status = host_status; 765 766 switch (host_status) { 767 case HOST_OK: 768 /* The host is known and the key matches. */ 769 debug("Host '%.200s' is known and matches the %s host %s.", 770 host, type, want_cert ? "certificate" : "key"); 771 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", 772 host_found->file, host_found->line); 773 if (want_cert && 774 !check_host_cert(options.host_key_alias == NULL ? 775 hostname : options.host_key_alias, host_key)) 776 goto fail; 777 if (options.check_host_ip && ip_status == HOST_NEW) { 778 if (readonly || want_cert) 779 logit("%s host key for IP address " 780 "'%.128s' not in list of known hosts.", 781 type, ip); 782 else if (!add_host_to_hostfile(user_hostfiles[0], ip, 783 host_key, options.hash_known_hosts)) 784 logit("Failed to add the %s host key for IP " 785 "address '%.128s' to the list of known " 786 "hosts (%.500s).", type, ip, 787 user_hostfiles[0]); 788 else 789 logit("Warning: Permanently added the %s host " 790 "key for IP address '%.128s' to the list " 791 "of known hosts.", type, ip); 792 } else if (options.visual_host_key) { 793 fp = sshkey_fingerprint(host_key, 794 options.fingerprint_hash, SSH_FP_DEFAULT); 795 ra = sshkey_fingerprint(host_key, 796 options.fingerprint_hash, SSH_FP_RANDOMART); 797 if (fp == NULL || ra == NULL) 798 fatal("%s: sshkey_fingerprint fail", __func__); 799 logit("Host key fingerprint is %s\n%s", fp, ra); 800 free(ra); 801 free(fp); 802 } 803 hostkey_trusted = 1; 804 break; 805 case HOST_NEW: 806 if (options.host_key_alias == NULL && port != 0 && 807 port != SSH_DEFAULT_PORT) { 808 debug("checking without port identifier"); 809 if (check_host_key(hostname, hostaddr, 0, host_key, 810 ROQUIET, user_hostfiles, num_user_hostfiles, 811 system_hostfiles, num_system_hostfiles) == 0) { 812 debug("found matching key w/out port"); 813 break; 814 } 815 } 816 if (readonly || want_cert) 817 goto fail; 818 /* The host is new. */ 819 if (options.strict_host_key_checking == 820 SSH_STRICT_HOSTKEY_YES) { 821 /* 822 * User has requested strict host key checking. We 823 * will not add the host key automatically. The only 824 * alternative left is to abort. 825 */ 826 error("No %s host key is known for %.200s and you " 827 "have requested strict checking.", type, host); 828 goto fail; 829 } else if (options.strict_host_key_checking == 830 SSH_STRICT_HOSTKEY_ASK) { 831 char msg1[1024], msg2[1024]; 832 833 if (show_other_keys(host_hostkeys, host_key)) 834 snprintf(msg1, sizeof(msg1), 835 "\nbut keys of different type are already" 836 " known for this host."); 837 else 838 snprintf(msg1, sizeof(msg1), "."); 839 /* The default */ 840 fp = sshkey_fingerprint(host_key, 841 options.fingerprint_hash, SSH_FP_DEFAULT); 842 ra = sshkey_fingerprint(host_key, 843 options.fingerprint_hash, SSH_FP_RANDOMART); 844 if (fp == NULL || ra == NULL) 845 fatal("%s: sshkey_fingerprint fail", __func__); 846 msg2[0] = '\0'; 847 if (options.verify_host_key_dns) { 848 if (matching_host_key_dns) 849 snprintf(msg2, sizeof(msg2), 850 "Matching host key fingerprint" 851 " found in DNS.\n"); 852 else 853 snprintf(msg2, sizeof(msg2), 854 "No matching host key fingerprint" 855 " found in DNS.\n"); 856 } 857 snprintf(msg, sizeof(msg), 858 "The authenticity of host '%.200s (%s)' can't be " 859 "established%s\n" 860 "%s key fingerprint is %s.%s%s\n%s" 861 "Are you sure you want to continue connecting " 862 "(yes/no/[fingerprint])? ", 863 host, ip, msg1, type, fp, 864 options.visual_host_key ? "\n" : "", 865 options.visual_host_key ? ra : "", 866 msg2); 867 free(ra); 868 confirmed = confirm(msg, fp); 869 free(fp); 870 if (!confirmed) 871 goto fail; 872 hostkey_trusted = 1; /* user explicitly confirmed */ 873 } 874 /* 875 * If in "new" or "off" strict mode, add the key automatically 876 * to the local known_hosts file. 877 */ 878 if (options.check_host_ip && ip_status == HOST_NEW) { 879 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); 880 hostp = hostline; 881 if (options.hash_known_hosts) { 882 /* Add hash of host and IP separately */ 883 r = add_host_to_hostfile(user_hostfiles[0], 884 host, host_key, options.hash_known_hosts) && 885 add_host_to_hostfile(user_hostfiles[0], ip, 886 host_key, options.hash_known_hosts); 887 } else { 888 /* Add unhashed "host,ip" */ 889 r = add_host_to_hostfile(user_hostfiles[0], 890 hostline, host_key, 891 options.hash_known_hosts); 892 } 893 } else { 894 r = add_host_to_hostfile(user_hostfiles[0], host, 895 host_key, options.hash_known_hosts); 896 hostp = host; 897 } 898 899 if (!r) 900 logit("Failed to add the host to the list of known " 901 "hosts (%.500s).", user_hostfiles[0]); 902 else 903 logit("Warning: Permanently added '%.200s' (%s) to the " 904 "list of known hosts.", hostp, type); 905 break; 906 case HOST_REVOKED: 907 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 908 error("@ WARNING: REVOKED HOST KEY DETECTED! @"); 909 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 910 error("The %s host key for %s is marked as revoked.", type, host); 911 error("This could mean that a stolen key is being used to"); 912 error("impersonate this host."); 913 914 /* 915 * If strict host key checking is in use, the user will have 916 * to edit the key manually and we can only abort. 917 */ 918 if (options.strict_host_key_checking != 919 SSH_STRICT_HOSTKEY_OFF) { 920 error("%s host key for %.200s was revoked and you have " 921 "requested strict checking.", type, host); 922 goto fail; 923 } 924 goto continue_unsafe; 925 926 case HOST_CHANGED: 927 if (want_cert) { 928 /* 929 * This is only a debug() since it is valid to have 930 * CAs with wildcard DNS matches that don't match 931 * all hosts that one might visit. 932 */ 933 debug("Host certificate authority does not " 934 "match %s in %s:%lu", CA_MARKER, 935 host_found->file, host_found->line); 936 goto fail; 937 } 938 if (readonly == ROQUIET) 939 goto fail; 940 if (options.check_host_ip && host_ip_differ) { 941 char *key_msg; 942 if (ip_status == HOST_NEW) 943 key_msg = "is unknown"; 944 else if (ip_status == HOST_OK) 945 key_msg = "is unchanged"; 946 else 947 key_msg = "has a different value"; 948 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 949 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); 950 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 951 error("The %s host key for %s has changed,", type, host); 952 error("and the key for the corresponding IP address %s", ip); 953 error("%s. This could either mean that", key_msg); 954 error("DNS SPOOFING is happening or the IP address for the host"); 955 error("and its host key have changed at the same time."); 956 if (ip_status != HOST_NEW) 957 error("Offending key for IP in %s:%lu", 958 ip_found->file, ip_found->line); 959 } 960 /* The host key has changed. */ 961 warn_changed_key(host_key); 962 error("Add correct host key in %.100s to get rid of this message.", 963 user_hostfiles[0]); 964 error("Offending %s key in %s:%lu", 965 sshkey_type(host_found->key), 966 host_found->file, host_found->line); 967 968 /* 969 * If strict host key checking is in use, the user will have 970 * to edit the key manually and we can only abort. 971 */ 972 if (options.strict_host_key_checking != 973 SSH_STRICT_HOSTKEY_OFF) { 974 error("%s host key for %.200s has changed and you have " 975 "requested strict checking.", type, host); 976 goto fail; 977 } 978 979 continue_unsafe: 980 /* 981 * If strict host key checking has not been requested, allow 982 * the connection but without MITM-able authentication or 983 * forwarding. 984 */ 985 if (options.password_authentication) { 986 error("Password authentication is disabled to avoid " 987 "man-in-the-middle attacks."); 988 options.password_authentication = 0; 989 cancelled_forwarding = 1; 990 } 991 if (options.kbd_interactive_authentication) { 992 error("Keyboard-interactive authentication is disabled" 993 " to avoid man-in-the-middle attacks."); 994 options.kbd_interactive_authentication = 0; 995 options.challenge_response_authentication = 0; 996 cancelled_forwarding = 1; 997 } 998 if (options.challenge_response_authentication) { 999 error("Challenge/response authentication is disabled" 1000 " to avoid man-in-the-middle attacks."); 1001 options.challenge_response_authentication = 0; 1002 cancelled_forwarding = 1; 1003 } 1004 if (options.forward_agent) { 1005 error("Agent forwarding is disabled to avoid " 1006 "man-in-the-middle attacks."); 1007 options.forward_agent = 0; 1008 cancelled_forwarding = 1; 1009 } 1010 if (options.forward_x11) { 1011 error("X11 forwarding is disabled to avoid " 1012 "man-in-the-middle attacks."); 1013 options.forward_x11 = 0; 1014 cancelled_forwarding = 1; 1015 } 1016 if (options.num_local_forwards > 0 || 1017 options.num_remote_forwards > 0) { 1018 error("Port forwarding is disabled to avoid " 1019 "man-in-the-middle attacks."); 1020 options.num_local_forwards = 1021 options.num_remote_forwards = 0; 1022 cancelled_forwarding = 1; 1023 } 1024 if (options.tun_open != SSH_TUNMODE_NO) { 1025 error("Tunnel forwarding is disabled to avoid " 1026 "man-in-the-middle attacks."); 1027 options.tun_open = SSH_TUNMODE_NO; 1028 cancelled_forwarding = 1; 1029 } 1030 if (options.exit_on_forward_failure && cancelled_forwarding) 1031 fatal("Error: forwarding disabled due to host key " 1032 "check failure"); 1033 1034 /* 1035 * XXX Should permit the user to change to use the new id. 1036 * This could be done by converting the host key to an 1037 * identifying sentence, tell that the host identifies itself 1038 * by that sentence, and ask the user if he/she wishes to 1039 * accept the authentication. 1040 */ 1041 break; 1042 case HOST_FOUND: 1043 fatal("internal error"); 1044 break; 1045 } 1046 1047 if (options.check_host_ip && host_status != HOST_CHANGED && 1048 ip_status == HOST_CHANGED) { 1049 snprintf(msg, sizeof(msg), 1050 "Warning: the %s host key for '%.200s' " 1051 "differs from the key for the IP address '%.128s'" 1052 "\nOffending key for IP in %s:%lu", 1053 type, host, ip, ip_found->file, ip_found->line); 1054 if (host_status == HOST_OK) { 1055 len = strlen(msg); 1056 snprintf(msg + len, sizeof(msg) - len, 1057 "\nMatching host key in %s:%lu", 1058 host_found->file, host_found->line); 1059 } 1060 if (options.strict_host_key_checking == 1061 SSH_STRICT_HOSTKEY_ASK) { 1062 strlcat(msg, "\nAre you sure you want " 1063 "to continue connecting (yes/no)? ", sizeof(msg)); 1064 if (!confirm(msg, NULL)) 1065 goto fail; 1066 } else if (options.strict_host_key_checking != 1067 SSH_STRICT_HOSTKEY_OFF) { 1068 logit("%s", msg); 1069 error("Exiting, you have requested strict checking."); 1070 goto fail; 1071 } else { 1072 logit("%s", msg); 1073 } 1074 } 1075 1076 if (!hostkey_trusted && options.update_hostkeys) { 1077 debug("%s: hostkey not known or explicitly trusted: " 1078 "disabling UpdateHostkeys", __func__); 1079 options.update_hostkeys = 0; 1080 } 1081 1082 free(ip); 1083 free(host); 1084 if (host_hostkeys != NULL) 1085 free_hostkeys(host_hostkeys); 1086 if (ip_hostkeys != NULL) 1087 free_hostkeys(ip_hostkeys); 1088 return 0; 1089 1090 fail: 1091 if (want_cert && host_status != HOST_REVOKED) { 1092 /* 1093 * No matching certificate. Downgrade cert to raw key and 1094 * search normally. 1095 */ 1096 debug("No matching CA found. Retry with plain key"); 1097 if ((r = sshkey_from_private(host_key, &raw_key)) != 0) 1098 fatal("%s: sshkey_from_private: %s", 1099 __func__, ssh_err(r)); 1100 if ((r = sshkey_drop_cert(raw_key)) != 0) 1101 fatal("Couldn't drop certificate: %s", ssh_err(r)); 1102 host_key = raw_key; 1103 goto retry; 1104 } 1105 sshkey_free(raw_key); 1106 free(ip); 1107 free(host); 1108 if (host_hostkeys != NULL) 1109 free_hostkeys(host_hostkeys); 1110 if (ip_hostkeys != NULL) 1111 free_hostkeys(ip_hostkeys); 1112 return -1; 1113 } 1114 1115 /* returns 0 if key verifies or -1 if key does NOT verify */ 1116 int 1117 verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key) 1118 { 1119 u_int i; 1120 int r = -1, flags = 0; 1121 char valid[64], *fp = NULL, *cafp = NULL; 1122 struct sshkey *plain = NULL; 1123 1124 if ((fp = sshkey_fingerprint(host_key, 1125 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1126 error("%s: fingerprint host key: %s", __func__, ssh_err(r)); 1127 r = -1; 1128 goto out; 1129 } 1130 1131 if (sshkey_is_cert(host_key)) { 1132 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, 1133 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { 1134 error("%s: fingerprint CA key: %s", 1135 __func__, ssh_err(r)); 1136 r = -1; 1137 goto out; 1138 } 1139 sshkey_format_cert_validity(host_key->cert, 1140 valid, sizeof(valid)); 1141 debug("Server host certificate: %s %s, serial %llu " 1142 "ID \"%s\" CA %s %s valid %s", 1143 sshkey_ssh_name(host_key), fp, 1144 (unsigned long long)host_key->cert->serial, 1145 host_key->cert->key_id, 1146 sshkey_ssh_name(host_key->cert->signature_key), cafp, 1147 valid); 1148 for (i = 0; i < host_key->cert->nprincipals; i++) { 1149 debug2("Server host certificate hostname: %s", 1150 host_key->cert->principals[i]); 1151 } 1152 } else { 1153 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp); 1154 } 1155 1156 if (sshkey_equal(previous_host_key, host_key)) { 1157 debug2("%s: server host key %s %s matches cached key", 1158 __func__, sshkey_type(host_key), fp); 1159 r = 0; 1160 goto out; 1161 } 1162 1163 /* Check in RevokedHostKeys file if specified */ 1164 if (options.revoked_host_keys != NULL) { 1165 r = sshkey_check_revoked(host_key, options.revoked_host_keys); 1166 switch (r) { 1167 case 0: 1168 break; /* not revoked */ 1169 case SSH_ERR_KEY_REVOKED: 1170 error("Host key %s %s revoked by file %s", 1171 sshkey_type(host_key), fp, 1172 options.revoked_host_keys); 1173 r = -1; 1174 goto out; 1175 default: 1176 error("Error checking host key %s %s in " 1177 "revoked keys file %s: %s", sshkey_type(host_key), 1178 fp, options.revoked_host_keys, ssh_err(r)); 1179 r = -1; 1180 goto out; 1181 } 1182 } 1183 1184 if (options.verify_host_key_dns) { 1185 /* 1186 * XXX certs are not yet supported for DNS, so downgrade 1187 * them and try the plain key. 1188 */ 1189 if ((r = sshkey_from_private(host_key, &plain)) != 0) 1190 goto out; 1191 if (sshkey_is_cert(plain)) 1192 sshkey_drop_cert(plain); 1193 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { 1194 if (flags & DNS_VERIFY_FOUND) { 1195 if (options.verify_host_key_dns == 1 && 1196 flags & DNS_VERIFY_MATCH && 1197 flags & DNS_VERIFY_SECURE) { 1198 r = 0; 1199 goto out; 1200 } 1201 if (flags & DNS_VERIFY_MATCH) { 1202 matching_host_key_dns = 1; 1203 } else { 1204 warn_changed_key(plain); 1205 error("Update the SSHFP RR in DNS " 1206 "with the new host key to get rid " 1207 "of this message."); 1208 } 1209 } 1210 } 1211 } 1212 r = check_host_key(host, hostaddr, options.port, host_key, RDRW, 1213 options.user_hostfiles, options.num_user_hostfiles, 1214 options.system_hostfiles, options.num_system_hostfiles); 1215 1216 out: 1217 sshkey_free(plain); 1218 free(fp); 1219 free(cafp); 1220 if (r == 0 && host_key != NULL) { 1221 sshkey_free(previous_host_key); 1222 r = sshkey_from_private(host_key, &previous_host_key); 1223 } 1224 1225 return r; 1226 } 1227 1228 /* 1229 * Starts a dialog with the server, and authenticates the current user on the 1230 * server. This does not need any extra privileges. The basic connection 1231 * to the server must already have been established before this is called. 1232 * If login fails, this function prints an error and never returns. 1233 * This function does not require super-user privileges. 1234 */ 1235 void 1236 ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost, 1237 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms) 1238 { 1239 char *host; 1240 char *server_user, *local_user; 1241 1242 local_user = xstrdup(pw->pw_name); 1243 server_user = options.user ? options.user : local_user; 1244 1245 /* Convert the user-supplied hostname into all lowercase. */ 1246 host = xstrdup(orighost); 1247 lowercase(host); 1248 1249 /* Exchange protocol version identification strings with the server. */ 1250 if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0) 1251 cleanup_exit(255); /* error already logged */ 1252 1253 /* Put the connection into non-blocking mode. */ 1254 ssh_packet_set_nonblocking(ssh); 1255 1256 /* key exchange */ 1257 /* authenticate user */ 1258 debug("Authenticating to %s:%d as '%s'", host, port, server_user); 1259 ssh_kex2(ssh, host, hostaddr, port); 1260 ssh_userauth2(ssh, local_user, server_user, host, sensitive); 1261 free(local_user); 1262 free(host); 1263 } 1264 1265 /* print all known host keys for a given host, but skip keys of given type */ 1266 static int 1267 show_other_keys(struct hostkeys *hostkeys, struct sshkey *key) 1268 { 1269 int type[] = { 1270 KEY_RSA, 1271 KEY_DSA, 1272 KEY_ECDSA, 1273 KEY_ED25519, 1274 KEY_XMSS, 1275 -1 1276 }; 1277 int i, ret = 0; 1278 char *fp, *ra; 1279 const struct hostkey_entry *found; 1280 1281 for (i = 0; type[i] != -1; i++) { 1282 if (type[i] == key->type) 1283 continue; 1284 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found)) 1285 continue; 1286 fp = sshkey_fingerprint(found->key, 1287 options.fingerprint_hash, SSH_FP_DEFAULT); 1288 ra = sshkey_fingerprint(found->key, 1289 options.fingerprint_hash, SSH_FP_RANDOMART); 1290 if (fp == NULL || ra == NULL) 1291 fatal("%s: sshkey_fingerprint fail", __func__); 1292 logit("WARNING: %s key found for host %s\n" 1293 "in %s:%lu\n" 1294 "%s key fingerprint %s.", 1295 sshkey_type(found->key), 1296 found->host, found->file, found->line, 1297 sshkey_type(found->key), fp); 1298 if (options.visual_host_key) 1299 logit("%s", ra); 1300 free(ra); 1301 free(fp); 1302 ret = 1; 1303 } 1304 return ret; 1305 } 1306 1307 static void 1308 warn_changed_key(struct sshkey *host_key) 1309 { 1310 char *fp; 1311 1312 fp = sshkey_fingerprint(host_key, options.fingerprint_hash, 1313 SSH_FP_DEFAULT); 1314 if (fp == NULL) 1315 fatal("%s: sshkey_fingerprint fail", __func__); 1316 1317 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1318 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); 1319 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 1320 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); 1321 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); 1322 error("It is also possible that a host key has just been changed."); 1323 error("The fingerprint for the %s key sent by the remote host is\n%s.", 1324 sshkey_type(host_key), fp); 1325 error("Please contact your system administrator."); 1326 1327 free(fp); 1328 } 1329 1330 /* 1331 * Execute a local command 1332 */ 1333 int 1334 ssh_local_cmd(const char *args) 1335 { 1336 char *shell; 1337 pid_t pid; 1338 int status; 1339 void (*osighand)(int); 1340 1341 if (!options.permit_local_command || 1342 args == NULL || !*args) 1343 return (1); 1344 1345 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 1346 shell = _PATH_BSHELL; 1347 1348 osighand = ssh_signal(SIGCHLD, SIG_DFL); 1349 pid = fork(); 1350 if (pid == 0) { 1351 ssh_signal(SIGPIPE, SIG_DFL); 1352 debug3("Executing %s -c \"%s\"", shell, args); 1353 execl(shell, shell, "-c", args, (char *)NULL); 1354 error("Couldn't execute %s -c \"%s\": %s", 1355 shell, args, strerror(errno)); 1356 _exit(1); 1357 } else if (pid == -1) 1358 fatal("fork failed: %.100s", strerror(errno)); 1359 while (waitpid(pid, &status, 0) == -1) 1360 if (errno != EINTR) 1361 fatal("Couldn't wait for child: %s", strerror(errno)); 1362 ssh_signal(SIGCHLD, osighand); 1363 1364 if (!WIFEXITED(status)) 1365 return (1); 1366 1367 return (WEXITSTATUS(status)); 1368 } 1369 1370 void 1371 maybe_add_key_to_agent(const char *authfile, struct sshkey *private, 1372 const char *comment, const char *passphrase) 1373 { 1374 int auth_sock = -1, r; 1375 const char *skprovider = NULL; 1376 1377 if (options.add_keys_to_agent == 0) 1378 return; 1379 1380 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 1381 debug3("no authentication agent, not adding key"); 1382 return; 1383 } 1384 1385 if (options.add_keys_to_agent == 2 && 1386 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { 1387 debug3("user denied adding this key"); 1388 close(auth_sock); 1389 return; 1390 } 1391 if (sshkey_is_sk(private)) 1392 skprovider = options.sk_provider; 1393 if ((r = ssh_add_identity_constrained(auth_sock, private, 1394 comment == NULL ? authfile : comment, 0, 1395 (options.add_keys_to_agent == 3), 0, skprovider)) == 0) 1396 debug("identity added to agent: %s", authfile); 1397 else 1398 debug("could not add identity to agent: %s (%d)", authfile, r); 1399 close(auth_sock); 1400 } 1401