1 /* $OpenBSD: ssh-keyscan.c,v 1.82 2010/06/22 04:54:30 djm Exp $ */ 2 /* 3 * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>. 4 * 5 * Modification and redistribution in source and binary forms is 6 * permitted provided that due credit is given to the author and the 7 * OpenBSD project by leaving this copyright notice intact. 8 */ 9 10 #include "includes.h" 11 12 #include "openbsd-compat/sys-queue.h" 13 #include <sys/resource.h> 14 #ifdef HAVE_SYS_TIME_H 15 # include <sys/time.h> 16 #endif 17 18 #include <netinet/in.h> 19 #include <arpa/inet.h> 20 21 #include <openssl/bn.h> 22 23 #include <netdb.h> 24 #include <errno.h> 25 #include <setjmp.h> 26 #include <stdarg.h> 27 #include <stdio.h> 28 #include <stdlib.h> 29 #include <signal.h> 30 #include <string.h> 31 #include <unistd.h> 32 33 #include "xmalloc.h" 34 #include "ssh.h" 35 #include "ssh1.h" 36 #include "buffer.h" 37 #include "key.h" 38 #include "cipher.h" 39 #include "kex.h" 40 #include "compat.h" 41 #include "myproposal.h" 42 #include "packet.h" 43 #include "dispatch.h" 44 #include "log.h" 45 #include "atomicio.h" 46 #include "misc.h" 47 #include "hostfile.h" 48 49 /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. 50 Default value is AF_UNSPEC means both IPv4 and IPv6. */ 51 int IPv4or6 = AF_UNSPEC; 52 53 int ssh_port = SSH_DEFAULT_PORT; 54 55 #define KT_RSA1 1 56 #define KT_DSA 2 57 #define KT_RSA 4 58 59 int get_keytypes = KT_RSA; /* Get only RSA keys by default */ 60 61 int hash_hosts = 0; /* Hash hostname on output */ 62 63 #define MAXMAXFD 256 64 65 /* The number of seconds after which to give up on a TCP connection */ 66 int timeout = 5; 67 68 int maxfd; 69 #define MAXCON (maxfd - 10) 70 71 extern char *__progname; 72 fd_set *read_wait; 73 size_t read_wait_nfdset; 74 int ncon; 75 int nonfatal_fatal = 0; 76 jmp_buf kexjmp; 77 Key *kexjmp_key; 78 79 /* 80 * Keep a connection structure for each file descriptor. The state 81 * associated with file descriptor n is held in fdcon[n]. 82 */ 83 typedef struct Connection { 84 u_char c_status; /* State of connection on this file desc. */ 85 #define CS_UNUSED 0 /* File descriptor unused */ 86 #define CS_CON 1 /* Waiting to connect/read greeting */ 87 #define CS_SIZE 2 /* Waiting to read initial packet size */ 88 #define CS_KEYS 3 /* Waiting to read public key packet */ 89 int c_fd; /* Quick lookup: c->c_fd == c - fdcon */ 90 int c_plen; /* Packet length field for ssh packet */ 91 int c_len; /* Total bytes which must be read. */ 92 int c_off; /* Length of data read so far. */ 93 int c_keytype; /* Only one of KT_RSA1, KT_DSA, or KT_RSA */ 94 char *c_namebase; /* Address to free for c_name and c_namelist */ 95 char *c_name; /* Hostname of connection for errors */ 96 char *c_namelist; /* Pointer to other possible addresses */ 97 char *c_output_name; /* Hostname of connection for output */ 98 char *c_data; /* Data read from this fd */ 99 Kex *c_kex; /* The key-exchange struct for ssh2 */ 100 struct timeval c_tv; /* Time at which connection gets aborted */ 101 TAILQ_ENTRY(Connection) c_link; /* List of connections in timeout order. */ 102 } con; 103 104 TAILQ_HEAD(conlist, Connection) tq; /* Timeout Queue */ 105 con *fdcon; 106 107 static int 108 fdlim_get(int hard) 109 { 110 #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE) 111 struct rlimit rlfd; 112 113 if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0) 114 return (-1); 115 if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY) 116 return SSH_SYSFDMAX; 117 else 118 return hard ? rlfd.rlim_max : rlfd.rlim_cur; 119 #else 120 return SSH_SYSFDMAX; 121 #endif 122 } 123 124 static int 125 fdlim_set(int lim) 126 { 127 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE) 128 struct rlimit rlfd; 129 #endif 130 131 if (lim <= 0) 132 return (-1); 133 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE) 134 if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0) 135 return (-1); 136 rlfd.rlim_cur = lim; 137 if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0) 138 return (-1); 139 #elif defined (HAVE_SETDTABLESIZE) 140 setdtablesize(lim); 141 #endif 142 return (0); 143 } 144 145 /* 146 * This is an strsep function that returns a null field for adjacent 147 * separators. This is the same as the 4.4BSD strsep, but different from the 148 * one in the GNU libc. 149 */ 150 static char * 151 xstrsep(char **str, const char *delim) 152 { 153 char *s, *e; 154 155 if (!**str) 156 return (NULL); 157 158 s = *str; 159 e = s + strcspn(s, delim); 160 161 if (*e != '\0') 162 *e++ = '\0'; 163 *str = e; 164 165 return (s); 166 } 167 168 /* 169 * Get the next non-null token (like GNU strsep). Strsep() will return a 170 * null token for two adjacent separators, so we may have to loop. 171 */ 172 static char * 173 strnnsep(char **stringp, char *delim) 174 { 175 char *tok; 176 177 do { 178 tok = xstrsep(stringp, delim); 179 } while (tok && *tok == '\0'); 180 return (tok); 181 } 182 183 static Key * 184 keygrab_ssh1(con *c) 185 { 186 static Key *rsa; 187 static Buffer msg; 188 189 if (rsa == NULL) { 190 buffer_init(&msg); 191 rsa = key_new(KEY_RSA1); 192 } 193 buffer_append(&msg, c->c_data, c->c_plen); 194 buffer_consume(&msg, 8 - (c->c_plen & 7)); /* padding */ 195 if (buffer_get_char(&msg) != (int) SSH_SMSG_PUBLIC_KEY) { 196 error("%s: invalid packet type", c->c_name); 197 buffer_clear(&msg); 198 return NULL; 199 } 200 buffer_consume(&msg, 8); /* cookie */ 201 202 /* server key */ 203 (void) buffer_get_int(&msg); 204 buffer_get_bignum(&msg, rsa->rsa->e); 205 buffer_get_bignum(&msg, rsa->rsa->n); 206 207 /* host key */ 208 (void) buffer_get_int(&msg); 209 buffer_get_bignum(&msg, rsa->rsa->e); 210 buffer_get_bignum(&msg, rsa->rsa->n); 211 212 buffer_clear(&msg); 213 214 return (rsa); 215 } 216 217 static int 218 hostjump(Key *hostkey) 219 { 220 kexjmp_key = hostkey; 221 longjmp(kexjmp, 1); 222 } 223 224 static int 225 ssh2_capable(int remote_major, int remote_minor) 226 { 227 switch (remote_major) { 228 case 1: 229 if (remote_minor == 99) 230 return 1; 231 break; 232 case 2: 233 return 1; 234 default: 235 break; 236 } 237 return 0; 238 } 239 240 static Key * 241 keygrab_ssh2(con *c) 242 { 243 int j; 244 245 packet_set_connection(c->c_fd, c->c_fd); 246 enable_compat20(); 247 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = c->c_keytype == KT_DSA? 248 "ssh-dss": "ssh-rsa"; 249 c->c_kex = kex_setup(myproposal); 250 c->c_kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 251 c->c_kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 252 c->c_kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 253 c->c_kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 254 c->c_kex->verify_host_key = hostjump; 255 256 if (!(j = setjmp(kexjmp))) { 257 nonfatal_fatal = 1; 258 dispatch_run(DISPATCH_BLOCK, &c->c_kex->done, c->c_kex); 259 fprintf(stderr, "Impossible! dispatch_run() returned!\n"); 260 exit(1); 261 } 262 nonfatal_fatal = 0; 263 xfree(c->c_kex); 264 c->c_kex = NULL; 265 packet_close(); 266 267 return j < 0? NULL : kexjmp_key; 268 } 269 270 static void 271 keyprint(con *c, Key *key) 272 { 273 char *host = c->c_output_name ? c->c_output_name : c->c_name; 274 275 if (!key) 276 return; 277 if (hash_hosts && (host = host_hash(host, NULL, 0)) == NULL) 278 fatal("host_hash failed"); 279 280 fprintf(stdout, "%s ", host); 281 key_write(key, stdout); 282 fputs("\n", stdout); 283 } 284 285 static int 286 tcpconnect(char *host) 287 { 288 struct addrinfo hints, *ai, *aitop; 289 char strport[NI_MAXSERV]; 290 int gaierr, s = -1; 291 292 snprintf(strport, sizeof strport, "%d", ssh_port); 293 memset(&hints, 0, sizeof(hints)); 294 hints.ai_family = IPv4or6; 295 hints.ai_socktype = SOCK_STREAM; 296 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) 297 fatal("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr)); 298 for (ai = aitop; ai; ai = ai->ai_next) { 299 s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 300 if (s < 0) { 301 error("socket: %s", strerror(errno)); 302 continue; 303 } 304 if (set_nonblock(s) == -1) 305 fatal("%s: set_nonblock(%d)", __func__, s); 306 if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 && 307 errno != EINPROGRESS) 308 error("connect (`%s'): %s", host, strerror(errno)); 309 else 310 break; 311 close(s); 312 s = -1; 313 } 314 freeaddrinfo(aitop); 315 return s; 316 } 317 318 static int 319 conalloc(char *iname, char *oname, int keytype) 320 { 321 char *namebase, *name, *namelist; 322 int s; 323 324 namebase = namelist = xstrdup(iname); 325 326 do { 327 name = xstrsep(&namelist, ","); 328 if (!name) { 329 xfree(namebase); 330 return (-1); 331 } 332 } while ((s = tcpconnect(name)) < 0); 333 334 if (s >= maxfd) 335 fatal("conalloc: fdno %d too high", s); 336 if (fdcon[s].c_status) 337 fatal("conalloc: attempt to reuse fdno %d", s); 338 339 fdcon[s].c_fd = s; 340 fdcon[s].c_status = CS_CON; 341 fdcon[s].c_namebase = namebase; 342 fdcon[s].c_name = name; 343 fdcon[s].c_namelist = namelist; 344 fdcon[s].c_output_name = xstrdup(oname); 345 fdcon[s].c_data = (char *) &fdcon[s].c_plen; 346 fdcon[s].c_len = 4; 347 fdcon[s].c_off = 0; 348 fdcon[s].c_keytype = keytype; 349 gettimeofday(&fdcon[s].c_tv, NULL); 350 fdcon[s].c_tv.tv_sec += timeout; 351 TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link); 352 FD_SET(s, read_wait); 353 ncon++; 354 return (s); 355 } 356 357 static void 358 confree(int s) 359 { 360 if (s >= maxfd || fdcon[s].c_status == CS_UNUSED) 361 fatal("confree: attempt to free bad fdno %d", s); 362 close(s); 363 xfree(fdcon[s].c_namebase); 364 xfree(fdcon[s].c_output_name); 365 if (fdcon[s].c_status == CS_KEYS) 366 xfree(fdcon[s].c_data); 367 fdcon[s].c_status = CS_UNUSED; 368 fdcon[s].c_keytype = 0; 369 TAILQ_REMOVE(&tq, &fdcon[s], c_link); 370 FD_CLR(s, read_wait); 371 ncon--; 372 } 373 374 static void 375 contouch(int s) 376 { 377 TAILQ_REMOVE(&tq, &fdcon[s], c_link); 378 gettimeofday(&fdcon[s].c_tv, NULL); 379 fdcon[s].c_tv.tv_sec += timeout; 380 TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link); 381 } 382 383 static int 384 conrecycle(int s) 385 { 386 con *c = &fdcon[s]; 387 int ret; 388 389 ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype); 390 confree(s); 391 return (ret); 392 } 393 394 static void 395 congreet(int s) 396 { 397 int n = 0, remote_major = 0, remote_minor = 0; 398 char buf[256], *cp; 399 char remote_version[sizeof buf]; 400 size_t bufsiz; 401 con *c = &fdcon[s]; 402 403 for (;;) { 404 memset(buf, '\0', sizeof(buf)); 405 bufsiz = sizeof(buf); 406 cp = buf; 407 while (bufsiz-- && 408 (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') { 409 if (*cp == '\r') 410 *cp = '\n'; 411 cp++; 412 } 413 if (n != 1 || strncmp(buf, "SSH-", 4) == 0) 414 break; 415 } 416 if (n == 0) { 417 switch (errno) { 418 case EPIPE: 419 error("%s: Connection closed by remote host", c->c_name); 420 break; 421 case ECONNREFUSED: 422 break; 423 default: 424 error("read (%s): %s", c->c_name, strerror(errno)); 425 break; 426 } 427 conrecycle(s); 428 return; 429 } 430 if (*cp != '\n' && *cp != '\r') { 431 error("%s: bad greeting", c->c_name); 432 confree(s); 433 return; 434 } 435 *cp = '\0'; 436 if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", 437 &remote_major, &remote_minor, remote_version) == 3) 438 compat_datafellows(remote_version); 439 else 440 datafellows = 0; 441 if (c->c_keytype != KT_RSA1) { 442 if (!ssh2_capable(remote_major, remote_minor)) { 443 debug("%s doesn't support ssh2", c->c_name); 444 confree(s); 445 return; 446 } 447 } else if (remote_major != 1) { 448 debug("%s doesn't support ssh1", c->c_name); 449 confree(s); 450 return; 451 } 452 fprintf(stderr, "# %s %s\n", c->c_name, chop(buf)); 453 n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n", 454 c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2, 455 c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2); 456 if (n < 0 || (size_t)n >= sizeof(buf)) { 457 error("snprintf: buffer too small"); 458 confree(s); 459 return; 460 } 461 if (atomicio(vwrite, s, buf, n) != (size_t)n) { 462 error("write (%s): %s", c->c_name, strerror(errno)); 463 confree(s); 464 return; 465 } 466 if (c->c_keytype != KT_RSA1) { 467 keyprint(c, keygrab_ssh2(c)); 468 confree(s); 469 return; 470 } 471 c->c_status = CS_SIZE; 472 contouch(s); 473 } 474 475 static void 476 conread(int s) 477 { 478 con *c = &fdcon[s]; 479 size_t n; 480 481 if (c->c_status == CS_CON) { 482 congreet(s); 483 return; 484 } 485 n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off); 486 if (n == 0) { 487 error("read (%s): %s", c->c_name, strerror(errno)); 488 confree(s); 489 return; 490 } 491 c->c_off += n; 492 493 if (c->c_off == c->c_len) 494 switch (c->c_status) { 495 case CS_SIZE: 496 c->c_plen = htonl(c->c_plen); 497 c->c_len = c->c_plen + 8 - (c->c_plen & 7); 498 c->c_off = 0; 499 c->c_data = xmalloc(c->c_len); 500 c->c_status = CS_KEYS; 501 break; 502 case CS_KEYS: 503 keyprint(c, keygrab_ssh1(c)); 504 confree(s); 505 return; 506 default: 507 fatal("conread: invalid status %d", c->c_status); 508 break; 509 } 510 511 contouch(s); 512 } 513 514 static void 515 conloop(void) 516 { 517 struct timeval seltime, now; 518 fd_set *r, *e; 519 con *c; 520 int i; 521 522 gettimeofday(&now, NULL); 523 c = TAILQ_FIRST(&tq); 524 525 if (c && (c->c_tv.tv_sec > now.tv_sec || 526 (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) { 527 seltime = c->c_tv; 528 seltime.tv_sec -= now.tv_sec; 529 seltime.tv_usec -= now.tv_usec; 530 if (seltime.tv_usec < 0) { 531 seltime.tv_usec += 1000000; 532 seltime.tv_sec--; 533 } 534 } else 535 seltime.tv_sec = seltime.tv_usec = 0; 536 537 r = xcalloc(read_wait_nfdset, sizeof(fd_mask)); 538 e = xcalloc(read_wait_nfdset, sizeof(fd_mask)); 539 memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask)); 540 memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask)); 541 542 while (select(maxfd, r, NULL, e, &seltime) == -1 && 543 (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)) 544 ; 545 546 for (i = 0; i < maxfd; i++) { 547 if (FD_ISSET(i, e)) { 548 error("%s: exception!", fdcon[i].c_name); 549 confree(i); 550 } else if (FD_ISSET(i, r)) 551 conread(i); 552 } 553 xfree(r); 554 xfree(e); 555 556 c = TAILQ_FIRST(&tq); 557 while (c && (c->c_tv.tv_sec < now.tv_sec || 558 (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) { 559 int s = c->c_fd; 560 561 c = TAILQ_NEXT(c, c_link); 562 conrecycle(s); 563 } 564 } 565 566 static void 567 do_host(char *host) 568 { 569 char *name = strnnsep(&host, " \t\n"); 570 int j; 571 572 if (name == NULL) 573 return; 574 for (j = KT_RSA1; j <= KT_RSA; j *= 2) { 575 if (get_keytypes & j) { 576 while (ncon >= MAXCON) 577 conloop(); 578 conalloc(name, *host ? host : name, j); 579 } 580 } 581 } 582 583 void 584 fatal(const char *fmt,...) 585 { 586 va_list args; 587 588 va_start(args, fmt); 589 do_log(SYSLOG_LEVEL_FATAL, fmt, args); 590 va_end(args); 591 if (nonfatal_fatal) 592 longjmp(kexjmp, -1); 593 else 594 exit(255); 595 } 596 597 static void 598 usage(void) 599 { 600 fprintf(stderr, 601 "usage: %s [-46Hv] [-f file] [-p port] [-T timeout] [-t type]\n" 602 "\t\t [host | addrlist namelist] ...\n", 603 __progname); 604 exit(1); 605 } 606 607 int 608 main(int argc, char **argv) 609 { 610 int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO; 611 int opt, fopt_count = 0, j; 612 char *tname, *cp, line[NI_MAXHOST]; 613 FILE *fp; 614 u_long linenum; 615 616 extern int optind; 617 extern char *optarg; 618 619 __progname = ssh_get_progname(argv[0]); 620 init_rng(); 621 seed_rng(); 622 TAILQ_INIT(&tq); 623 624 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 625 sanitise_stdfd(); 626 627 if (argc <= 1) 628 usage(); 629 630 while ((opt = getopt(argc, argv, "Hv46p:T:t:f:")) != -1) { 631 switch (opt) { 632 case 'H': 633 hash_hosts = 1; 634 break; 635 case 'p': 636 ssh_port = a2port(optarg); 637 if (ssh_port <= 0) { 638 fprintf(stderr, "Bad port '%s'\n", optarg); 639 exit(1); 640 } 641 break; 642 case 'T': 643 timeout = convtime(optarg); 644 if (timeout == -1 || timeout == 0) { 645 fprintf(stderr, "Bad timeout '%s'\n", optarg); 646 usage(); 647 } 648 break; 649 case 'v': 650 if (!debug_flag) { 651 debug_flag = 1; 652 log_level = SYSLOG_LEVEL_DEBUG1; 653 } 654 else if (log_level < SYSLOG_LEVEL_DEBUG3) 655 log_level++; 656 else 657 fatal("Too high debugging level."); 658 break; 659 case 'f': 660 if (strcmp(optarg, "-") == 0) 661 optarg = NULL; 662 argv[fopt_count++] = optarg; 663 break; 664 case 't': 665 get_keytypes = 0; 666 tname = strtok(optarg, ","); 667 while (tname) { 668 int type = key_type_from_name(tname); 669 switch (type) { 670 case KEY_RSA1: 671 get_keytypes |= KT_RSA1; 672 break; 673 case KEY_DSA: 674 get_keytypes |= KT_DSA; 675 break; 676 case KEY_RSA: 677 get_keytypes |= KT_RSA; 678 break; 679 case KEY_UNSPEC: 680 fatal("unknown key type %s", tname); 681 } 682 tname = strtok(NULL, ","); 683 } 684 break; 685 case '4': 686 IPv4or6 = AF_INET; 687 break; 688 case '6': 689 IPv4or6 = AF_INET6; 690 break; 691 case '?': 692 default: 693 usage(); 694 } 695 } 696 if (optind == argc && !fopt_count) 697 usage(); 698 699 log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1); 700 701 maxfd = fdlim_get(1); 702 if (maxfd < 0) 703 fatal("%s: fdlim_get: bad value", __progname); 704 if (maxfd > MAXMAXFD) 705 maxfd = MAXMAXFD; 706 if (MAXCON <= 0) 707 fatal("%s: not enough file descriptors", __progname); 708 if (maxfd > fdlim_get(0)) 709 fdlim_set(maxfd); 710 fdcon = xcalloc(maxfd, sizeof(con)); 711 712 read_wait_nfdset = howmany(maxfd, NFDBITS); 713 read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask)); 714 715 for (j = 0; j < fopt_count; j++) { 716 if (argv[j] == NULL) 717 fp = stdin; 718 else if ((fp = fopen(argv[j], "r")) == NULL) 719 fatal("%s: %s: %s", __progname, argv[j], 720 strerror(errno)); 721 linenum = 0; 722 723 while (read_keyfile_line(fp, 724 argv[j] == NULL ? "(stdin)" : argv[j], line, sizeof(line), 725 &linenum) != -1) { 726 /* Chomp off trailing whitespace and comments */ 727 if ((cp = strchr(line, '#')) == NULL) 728 cp = line + strlen(line) - 1; 729 while (cp >= line) { 730 if (*cp == ' ' || *cp == '\t' || 731 *cp == '\n' || *cp == '#') 732 *cp-- = '\0'; 733 else 734 break; 735 } 736 737 /* Skip empty lines */ 738 if (*line == '\0') 739 continue; 740 741 do_host(line); 742 } 743 744 if (ferror(fp)) 745 fatal("%s: %s: %s", __progname, argv[j], 746 strerror(errno)); 747 748 fclose(fp); 749 } 750 751 while (optind < argc) 752 do_host(argv[optind++]); 753 754 while (ncon > 0) 755 conloop(); 756 757 return (0); 758 } 759