1 /* $OpenBSD: hostfile.c,v 1.90 2021/04/03 06:58:30 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 * Functions for manipulating the known hosts files. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * 15 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. 16 * Copyright (c) 1999 Niels Provos. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/types.h> 40 #include <sys/stat.h> 41 42 #include <netinet/in.h> 43 44 #include <errno.h> 45 #include <resolv.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <stdarg.h> 50 #include <unistd.h> 51 52 #include "xmalloc.h" 53 #include "match.h" 54 #include "sshkey.h" 55 #include "hostfile.h" 56 #include "log.h" 57 #include "misc.h" 58 #include "pathnames.h" 59 #include "ssherr.h" 60 #include "digest.h" 61 #include "hmac.h" 62 #include "sshbuf.h" 63 64 /* XXX hmac is too easy to dictionary attack; use bcrypt? */ 65 66 static int 67 extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len) 68 { 69 char *p, *b64salt; 70 u_int b64len; 71 int ret; 72 73 if (l < sizeof(HASH_MAGIC) - 1) { 74 debug2("extract_salt: string too short"); 75 return (-1); 76 } 77 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { 78 debug2("extract_salt: invalid magic identifier"); 79 return (-1); 80 } 81 s += sizeof(HASH_MAGIC) - 1; 82 l -= sizeof(HASH_MAGIC) - 1; 83 if ((p = memchr(s, HASH_DELIM, l)) == NULL) { 84 debug2("extract_salt: missing salt termination character"); 85 return (-1); 86 } 87 88 b64len = p - s; 89 /* Sanity check */ 90 if (b64len == 0 || b64len > 1024) { 91 debug2("extract_salt: bad encoded salt length %u", b64len); 92 return (-1); 93 } 94 b64salt = xmalloc(1 + b64len); 95 memcpy(b64salt, s, b64len); 96 b64salt[b64len] = '\0'; 97 98 ret = __b64_pton(b64salt, salt, salt_len); 99 free(b64salt); 100 if (ret == -1) { 101 debug2("extract_salt: salt decode error"); 102 return (-1); 103 } 104 if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) { 105 debug2("extract_salt: expected salt len %zd, got %d", 106 ssh_hmac_bytes(SSH_DIGEST_SHA1), ret); 107 return (-1); 108 } 109 110 return (0); 111 } 112 113 char * 114 host_hash(const char *host, const char *name_from_hostfile, u_int src_len) 115 { 116 struct ssh_hmac_ctx *ctx; 117 u_char salt[256], result[256]; 118 char uu_salt[512], uu_result[512]; 119 static char encoded[1024]; 120 u_int len; 121 122 len = ssh_digest_bytes(SSH_DIGEST_SHA1); 123 124 if (name_from_hostfile == NULL) { 125 /* Create new salt */ 126 arc4random_buf(salt, len); 127 } else { 128 /* Extract salt from known host entry */ 129 if (extract_salt(name_from_hostfile, src_len, salt, 130 sizeof(salt)) == -1) 131 return (NULL); 132 } 133 134 if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || 135 ssh_hmac_init(ctx, salt, len) < 0 || 136 ssh_hmac_update(ctx, host, strlen(host)) < 0 || 137 ssh_hmac_final(ctx, result, sizeof(result))) 138 fatal_f("ssh_hmac failed"); 139 ssh_hmac_free(ctx); 140 141 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || 142 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) 143 fatal_f("__b64_ntop failed"); 144 145 snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, 146 HASH_DELIM, uu_result); 147 148 return (encoded); 149 } 150 151 /* 152 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the 153 * pointer over the key. Skips any whitespace at the beginning and at end. 154 */ 155 156 int 157 hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret) 158 { 159 char *cp; 160 161 /* Skip leading whitespace. */ 162 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) 163 ; 164 165 if (sshkey_read(ret, &cp) != 0) 166 return 0; 167 168 /* Skip trailing whitespace. */ 169 for (; *cp == ' ' || *cp == '\t'; cp++) 170 ; 171 172 /* Return results. */ 173 *cpp = cp; 174 if (bitsp != NULL) 175 *bitsp = sshkey_size(ret); 176 return 1; 177 } 178 179 static HostkeyMarker 180 check_markers(char **cpp) 181 { 182 char marker[32], *sp, *cp = *cpp; 183 int ret = MRK_NONE; 184 185 while (*cp == '@') { 186 /* Only one marker is allowed */ 187 if (ret != MRK_NONE) 188 return MRK_ERROR; 189 /* Markers are terminated by whitespace */ 190 if ((sp = strchr(cp, ' ')) == NULL && 191 (sp = strchr(cp, '\t')) == NULL) 192 return MRK_ERROR; 193 /* Extract marker for comparison */ 194 if (sp <= cp + 1 || sp >= cp + sizeof(marker)) 195 return MRK_ERROR; 196 memcpy(marker, cp, sp - cp); 197 marker[sp - cp] = '\0'; 198 if (strcmp(marker, CA_MARKER) == 0) 199 ret = MRK_CA; 200 else if (strcmp(marker, REVOKE_MARKER) == 0) 201 ret = MRK_REVOKE; 202 else 203 return MRK_ERROR; 204 205 /* Skip past marker and any whitespace that follows it */ 206 cp = sp; 207 for (; *cp == ' ' || *cp == '\t'; cp++) 208 ; 209 } 210 *cpp = cp; 211 return ret; 212 } 213 214 struct hostkeys * 215 init_hostkeys(void) 216 { 217 struct hostkeys *ret = xcalloc(1, sizeof(*ret)); 218 219 ret->entries = NULL; 220 return ret; 221 } 222 223 struct load_callback_ctx { 224 const char *host; 225 u_long num_loaded; 226 struct hostkeys *hostkeys; 227 }; 228 229 static int 230 record_hostkey(struct hostkey_foreach_line *l, void *_ctx) 231 { 232 struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx; 233 struct hostkeys *hostkeys = ctx->hostkeys; 234 struct hostkey_entry *tmp; 235 236 if (l->status == HKF_STATUS_INVALID) { 237 /* XXX make this verbose() in the future */ 238 debug("%s:%ld: parse error in hostkeys file", 239 l->path, l->linenum); 240 return 0; 241 } 242 243 debug3_f("found %skey type %s in file %s:%lu", 244 l->marker == MRK_NONE ? "" : 245 (l->marker == MRK_CA ? "ca " : "revoked "), 246 sshkey_type(l->key), l->path, l->linenum); 247 if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries, 248 hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL) 249 return SSH_ERR_ALLOC_FAIL; 250 hostkeys->entries = tmp; 251 hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host); 252 hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path); 253 hostkeys->entries[hostkeys->num_entries].line = l->linenum; 254 hostkeys->entries[hostkeys->num_entries].key = l->key; 255 l->key = NULL; /* steal it */ 256 hostkeys->entries[hostkeys->num_entries].marker = l->marker; 257 hostkeys->entries[hostkeys->num_entries].note = l->note; 258 hostkeys->num_entries++; 259 ctx->num_loaded++; 260 261 return 0; 262 } 263 264 void 265 load_hostkeys_file(struct hostkeys *hostkeys, const char *host, 266 const char *path, FILE *f, u_int note) 267 { 268 int r; 269 struct load_callback_ctx ctx; 270 271 ctx.host = host; 272 ctx.num_loaded = 0; 273 ctx.hostkeys = hostkeys; 274 275 if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host, 276 NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) { 277 if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT) 278 debug_fr(r, "hostkeys_foreach failed for %s", path); 279 } 280 if (ctx.num_loaded != 0) 281 debug3_f("loaded %lu keys from %s", ctx.num_loaded, host); 282 } 283 284 void 285 load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path, 286 u_int note) 287 { 288 FILE *f; 289 290 if ((f = fopen(path, "r")) == NULL) { 291 debug_f("fopen %s: %s", path, strerror(errno)); 292 return; 293 } 294 295 load_hostkeys_file(hostkeys, host, path, f, note); 296 fclose(f); 297 } 298 299 void 300 free_hostkeys(struct hostkeys *hostkeys) 301 { 302 u_int i; 303 304 for (i = 0; i < hostkeys->num_entries; i++) { 305 free(hostkeys->entries[i].host); 306 free(hostkeys->entries[i].file); 307 sshkey_free(hostkeys->entries[i].key); 308 explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); 309 } 310 free(hostkeys->entries); 311 freezero(hostkeys, sizeof(*hostkeys)); 312 } 313 314 static int 315 check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k) 316 { 317 int is_cert = sshkey_is_cert(k); 318 u_int i; 319 320 for (i = 0; i < hostkeys->num_entries; i++) { 321 if (hostkeys->entries[i].marker != MRK_REVOKE) 322 continue; 323 if (sshkey_equal_public(k, hostkeys->entries[i].key)) 324 return -1; 325 if (is_cert && k != NULL && 326 sshkey_equal_public(k->cert->signature_key, 327 hostkeys->entries[i].key)) 328 return -1; 329 } 330 return 0; 331 } 332 333 /* 334 * Match keys against a specified key, or look one up by key type. 335 * 336 * If looking for a keytype (key == NULL) and one is found then return 337 * HOST_FOUND, otherwise HOST_NEW. 338 * 339 * If looking for a key (key != NULL): 340 * 1. If the key is a cert and a matching CA is found, return HOST_OK 341 * 2. If the key is not a cert and a matching key is found, return HOST_OK 342 * 3. If no key matches but a key with a different type is found, then 343 * return HOST_CHANGED 344 * 4. If no matching keys are found, then return HOST_NEW. 345 * 346 * Finally, check any found key is not revoked. 347 */ 348 static HostStatus 349 check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, 350 struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found) 351 { 352 u_int i; 353 HostStatus end_return = HOST_NEW; 354 int want_cert = sshkey_is_cert(k); 355 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; 356 357 if (found != NULL) 358 *found = NULL; 359 360 for (i = 0; i < hostkeys->num_entries; i++) { 361 if (hostkeys->entries[i].marker != want_marker) 362 continue; 363 if (k == NULL) { 364 if (hostkeys->entries[i].key->type != keytype) 365 continue; 366 if (nid != -1 && 367 sshkey_type_plain(keytype) == KEY_ECDSA && 368 hostkeys->entries[i].key->ecdsa_nid != nid) 369 continue; 370 end_return = HOST_FOUND; 371 if (found != NULL) 372 *found = hostkeys->entries + i; 373 k = hostkeys->entries[i].key; 374 break; 375 } 376 if (want_cert) { 377 if (sshkey_equal_public(k->cert->signature_key, 378 hostkeys->entries[i].key)) { 379 /* A matching CA exists */ 380 end_return = HOST_OK; 381 if (found != NULL) 382 *found = hostkeys->entries + i; 383 break; 384 } 385 } else { 386 if (sshkey_equal(k, hostkeys->entries[i].key)) { 387 end_return = HOST_OK; 388 if (found != NULL) 389 *found = hostkeys->entries + i; 390 break; 391 } 392 /* A non-matching key exists */ 393 end_return = HOST_CHANGED; 394 if (found != NULL) 395 *found = hostkeys->entries + i; 396 } 397 } 398 if (check_key_not_revoked(hostkeys, k) != 0) { 399 end_return = HOST_REVOKED; 400 if (found != NULL) 401 *found = NULL; 402 } 403 return end_return; 404 } 405 406 HostStatus 407 check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key, 408 const struct hostkey_entry **found) 409 { 410 if (key == NULL) 411 fatal("no key to look up"); 412 return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found); 413 } 414 415 int 416 lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid, 417 const struct hostkey_entry **found) 418 { 419 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid, 420 found) == HOST_FOUND); 421 } 422 423 int 424 lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker) 425 { 426 u_int i; 427 428 for (i = 0; i < hostkeys->num_entries; i++) { 429 if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker) 430 return 1; 431 } 432 return 0; 433 } 434 435 static int 436 write_host_entry(FILE *f, const char *host, const char *ip, 437 const struct sshkey *key, int store_hash) 438 { 439 int r, success = 0; 440 char *hashed_host = NULL, *lhost; 441 442 lhost = xstrdup(host); 443 lowercase(lhost); 444 445 if (store_hash) { 446 if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) { 447 error_f("host_hash failed"); 448 free(lhost); 449 return 0; 450 } 451 fprintf(f, "%s ", hashed_host); 452 } else if (ip != NULL) 453 fprintf(f, "%s,%s ", lhost, ip); 454 else { 455 fprintf(f, "%s ", lhost); 456 } 457 free(lhost); 458 if ((r = sshkey_write(key, f)) == 0) 459 success = 1; 460 else 461 error_fr(r, "sshkey_write"); 462 fputc('\n', f); 463 /* If hashing is enabled, the IP address needs to go on its own line */ 464 if (success && store_hash && ip != NULL) 465 success = write_host_entry(f, ip, NULL, key, 1); 466 return success; 467 } 468 469 /* 470 * Create user ~/.ssh directory if it doesn't exist and we want to write to it. 471 * If notify is set, a message will be emitted if the directory is created. 472 */ 473 void 474 hostfile_create_user_ssh_dir(const char *filename, int notify) 475 { 476 char *dotsshdir = NULL, *p; 477 size_t len; 478 struct stat st; 479 480 if ((p = strrchr(filename, '/')) == NULL) 481 return; 482 len = p - filename; 483 dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid()); 484 if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0) 485 goto out; /* not ~/.ssh prefixed */ 486 if (stat(dotsshdir, &st) == 0) 487 goto out; /* dir already exists */ 488 else if (errno != ENOENT) 489 error("Could not stat %s: %s", dotsshdir, strerror(errno)); 490 else { 491 if (mkdir(dotsshdir, 0700) == -1) 492 error("Could not create directory '%.200s' (%s).", 493 dotsshdir, strerror(errno)); 494 else if (notify) 495 logit("Created directory '%s'.", dotsshdir); 496 } 497 out: 498 free(dotsshdir); 499 } 500 501 502 /* 503 * Appends an entry to the host file. Returns false if the entry could not 504 * be appended. 505 */ 506 int 507 add_host_to_hostfile(const char *filename, const char *host, 508 const struct sshkey *key, int store_hash) 509 { 510 FILE *f; 511 int success; 512 513 if (key == NULL) 514 return 1; /* XXX ? */ 515 hostfile_create_user_ssh_dir(filename, 0); 516 f = fopen(filename, "a"); 517 if (!f) 518 return 0; 519 success = write_host_entry(f, host, NULL, key, store_hash); 520 fclose(f); 521 return success; 522 } 523 524 struct host_delete_ctx { 525 FILE *out; 526 int quiet; 527 const char *host, *ip; 528 u_int *match_keys; /* mask of HKF_MATCH_* for this key */ 529 struct sshkey * const *keys; 530 size_t nkeys; 531 int modified; 532 }; 533 534 static int 535 host_delete(struct hostkey_foreach_line *l, void *_ctx) 536 { 537 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx; 538 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 539 size_t i; 540 541 /* Don't remove CA and revocation lines */ 542 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) { 543 /* 544 * If this line contains one of the keys that we will be 545 * adding later, then don't change it and mark the key for 546 * skipping. 547 */ 548 for (i = 0; i < ctx->nkeys; i++) { 549 if (!sshkey_equal(ctx->keys[i], l->key)) 550 continue; 551 ctx->match_keys[i] |= l->match; 552 fprintf(ctx->out, "%s\n", l->line); 553 debug3_f("%s key already at %s:%ld", 554 sshkey_type(l->key), l->path, l->linenum); 555 return 0; 556 } 557 558 /* 559 * Hostname matches and has no CA/revoke marker, delete it 560 * by *not* writing the line to ctx->out. 561 */ 562 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s", 563 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 564 l->path, l->linenum, sshkey_type(l->key), ctx->host); 565 ctx->modified = 1; 566 return 0; 567 } 568 /* Retain non-matching hosts and invalid lines when deleting */ 569 if (l->status == HKF_STATUS_INVALID) { 570 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry", 571 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 572 l->path, l->linenum); 573 } 574 fprintf(ctx->out, "%s\n", l->line); 575 return 0; 576 } 577 578 int 579 hostfile_replace_entries(const char *filename, const char *host, const char *ip, 580 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg) 581 { 582 int r, fd, oerrno = 0; 583 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 584 struct host_delete_ctx ctx; 585 char *fp, *temp = NULL, *back = NULL; 586 const char *what; 587 mode_t omask; 588 size_t i; 589 u_int want; 590 591 omask = umask(077); 592 593 memset(&ctx, 0, sizeof(ctx)); 594 ctx.host = host; 595 ctx.ip = ip; 596 ctx.quiet = quiet; 597 598 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL) 599 return SSH_ERR_ALLOC_FAIL; 600 ctx.keys = keys; 601 ctx.nkeys = nkeys; 602 ctx.modified = 0; 603 604 /* 605 * Prepare temporary file for in-place deletion. 606 */ 607 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 || 608 (r = asprintf(&back, "%s.old", filename)) == -1) { 609 r = SSH_ERR_ALLOC_FAIL; 610 goto fail; 611 } 612 613 if ((fd = mkstemp(temp)) == -1) { 614 oerrno = errno; 615 error_f("mkstemp: %s", strerror(oerrno)); 616 r = SSH_ERR_SYSTEM_ERROR; 617 goto fail; 618 } 619 if ((ctx.out = fdopen(fd, "w")) == NULL) { 620 oerrno = errno; 621 close(fd); 622 error_f("fdopen: %s", strerror(oerrno)); 623 r = SSH_ERR_SYSTEM_ERROR; 624 goto fail; 625 } 626 627 /* Remove stale/mismatching entries for the specified host */ 628 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip, 629 HKF_WANT_PARSE_KEY, 0)) != 0) { 630 oerrno = errno; 631 error_fr(r, "hostkeys_foreach"); 632 goto fail; 633 } 634 635 /* Re-add the requested keys */ 636 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP); 637 for (i = 0; i < nkeys; i++) { 638 if ((want & ctx.match_keys[i]) == want) 639 continue; 640 if ((fp = sshkey_fingerprint(keys[i], hash_alg, 641 SSH_FP_DEFAULT)) == NULL) { 642 r = SSH_ERR_ALLOC_FAIL; 643 goto fail; 644 } 645 /* write host/ip */ 646 what = ""; 647 if (ctx.match_keys[i] == 0) { 648 what = "Adding new key"; 649 if (!write_host_entry(ctx.out, host, ip, 650 keys[i], store_hash)) { 651 r = SSH_ERR_INTERNAL_ERROR; 652 goto fail; 653 } 654 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) { 655 what = "Fixing match (hostname)"; 656 if (!write_host_entry(ctx.out, host, NULL, 657 keys[i], store_hash)) { 658 r = SSH_ERR_INTERNAL_ERROR; 659 goto fail; 660 } 661 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) { 662 what = "Fixing match (address)"; 663 if (!write_host_entry(ctx.out, ip, NULL, 664 keys[i], store_hash)) { 665 r = SSH_ERR_INTERNAL_ERROR; 666 goto fail; 667 } 668 } 669 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s", 670 quiet ? __func__ : "", quiet ? ": " : "", what, 671 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename, 672 sshkey_ssh_name(keys[i]), fp); 673 free(fp); 674 ctx.modified = 1; 675 } 676 fclose(ctx.out); 677 ctx.out = NULL; 678 679 if (ctx.modified) { 680 /* Backup the original file and replace it with the temporary */ 681 if (unlink(back) == -1 && errno != ENOENT) { 682 oerrno = errno; 683 error_f("unlink %.100s: %s", back, strerror(errno)); 684 r = SSH_ERR_SYSTEM_ERROR; 685 goto fail; 686 } 687 if (link(filename, back) == -1) { 688 oerrno = errno; 689 error_f("link %.100s to %.100s: %s", filename, 690 back, strerror(errno)); 691 r = SSH_ERR_SYSTEM_ERROR; 692 goto fail; 693 } 694 if (rename(temp, filename) == -1) { 695 oerrno = errno; 696 error_f("rename \"%s\" to \"%s\": %s", temp, 697 filename, strerror(errno)); 698 r = SSH_ERR_SYSTEM_ERROR; 699 goto fail; 700 } 701 } else { 702 /* No changes made; just delete the temporary file */ 703 if (unlink(temp) != 0) 704 error_f("unlink \"%s\": %s", temp, strerror(errno)); 705 } 706 707 /* success */ 708 r = 0; 709 fail: 710 if (temp != NULL && r != 0) 711 unlink(temp); 712 free(temp); 713 free(back); 714 if (ctx.out != NULL) 715 fclose(ctx.out); 716 free(ctx.match_keys); 717 umask(omask); 718 if (r == SSH_ERR_SYSTEM_ERROR) 719 errno = oerrno; 720 return r; 721 } 722 723 static int 724 match_maybe_hashed(const char *host, const char *names, int *was_hashed) 725 { 726 int hashed = *names == HASH_DELIM; 727 const char *hashed_host; 728 size_t nlen = strlen(names); 729 730 if (was_hashed != NULL) 731 *was_hashed = hashed; 732 if (hashed) { 733 if ((hashed_host = host_hash(host, names, nlen)) == NULL) 734 return -1; 735 return nlen == strlen(hashed_host) && 736 strncmp(hashed_host, names, nlen) == 0; 737 } 738 return match_hostname(host, names) == 1; 739 } 740 741 int 742 hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback, 743 void *ctx, const char *host, const char *ip, u_int options, u_int note) 744 { 745 char *line = NULL, ktype[128]; 746 u_long linenum = 0; 747 char *cp, *cp2; 748 u_int kbits; 749 int hashed; 750 int s, r = 0; 751 struct hostkey_foreach_line lineinfo; 752 size_t linesize = 0, l; 753 754 memset(&lineinfo, 0, sizeof(lineinfo)); 755 if (host == NULL && (options & HKF_WANT_MATCH) != 0) 756 return SSH_ERR_INVALID_ARGUMENT; 757 758 while (getline(&line, &linesize, f) != -1) { 759 linenum++; 760 line[strcspn(line, "\n")] = '\0'; 761 762 free(lineinfo.line); 763 sshkey_free(lineinfo.key); 764 memset(&lineinfo, 0, sizeof(lineinfo)); 765 lineinfo.path = path; 766 lineinfo.linenum = linenum; 767 lineinfo.line = xstrdup(line); 768 lineinfo.marker = MRK_NONE; 769 lineinfo.status = HKF_STATUS_OK; 770 lineinfo.keytype = KEY_UNSPEC; 771 lineinfo.note = note; 772 773 /* Skip any leading whitespace, comments and empty lines. */ 774 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 775 ; 776 if (!*cp || *cp == '#' || *cp == '\n') { 777 if ((options & HKF_WANT_MATCH) == 0) { 778 lineinfo.status = HKF_STATUS_COMMENT; 779 if ((r = callback(&lineinfo, ctx)) != 0) 780 break; 781 } 782 continue; 783 } 784 785 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) { 786 verbose_f("invalid marker at %s:%lu", path, linenum); 787 if ((options & HKF_WANT_MATCH) == 0) 788 goto bad; 789 continue; 790 } 791 792 /* Find the end of the host name portion. */ 793 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) 794 ; 795 lineinfo.hosts = cp; 796 *cp2++ = '\0'; 797 798 /* Check if the host name matches. */ 799 if (host != NULL) { 800 if ((s = match_maybe_hashed(host, lineinfo.hosts, 801 &hashed)) == -1) { 802 debug2_f("%s:%ld: bad host hash \"%.32s\"", 803 path, linenum, lineinfo.hosts); 804 goto bad; 805 } 806 if (s == 1) { 807 lineinfo.status = HKF_STATUS_MATCHED; 808 lineinfo.match |= HKF_MATCH_HOST | 809 (hashed ? HKF_MATCH_HOST_HASHED : 0); 810 } 811 /* Try matching IP address if supplied */ 812 if (ip != NULL) { 813 if ((s = match_maybe_hashed(ip, lineinfo.hosts, 814 &hashed)) == -1) { 815 debug2_f("%s:%ld: bad ip hash " 816 "\"%.32s\"", path, linenum, 817 lineinfo.hosts); 818 goto bad; 819 } 820 if (s == 1) { 821 lineinfo.status = HKF_STATUS_MATCHED; 822 lineinfo.match |= HKF_MATCH_IP | 823 (hashed ? HKF_MATCH_IP_HASHED : 0); 824 } 825 } 826 /* 827 * Skip this line if host matching requested and 828 * neither host nor address matched. 829 */ 830 if ((options & HKF_WANT_MATCH) != 0 && 831 lineinfo.status != HKF_STATUS_MATCHED) 832 continue; 833 } 834 835 /* Got a match. Skip host name and any following whitespace */ 836 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 837 ; 838 if (*cp2 == '\0' || *cp2 == '#') { 839 debug2("%s:%ld: truncated before key type", 840 path, linenum); 841 goto bad; 842 } 843 lineinfo.rawkey = cp = cp2; 844 845 if ((options & HKF_WANT_PARSE_KEY) != 0) { 846 /* 847 * Extract the key from the line. This will skip 848 * any leading whitespace. Ignore badly formatted 849 * lines. 850 */ 851 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) { 852 error_f("sshkey_new failed"); 853 r = SSH_ERR_ALLOC_FAIL; 854 break; 855 } 856 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) { 857 goto bad; 858 } 859 lineinfo.keytype = lineinfo.key->type; 860 lineinfo.comment = cp; 861 } else { 862 /* Extract and parse key type */ 863 l = strcspn(lineinfo.rawkey, " \t"); 864 if (l <= 1 || l >= sizeof(ktype) || 865 lineinfo.rawkey[l] == '\0') 866 goto bad; 867 memcpy(ktype, lineinfo.rawkey, l); 868 ktype[l] = '\0'; 869 lineinfo.keytype = sshkey_type_from_name(ktype); 870 871 /* 872 * Assume legacy RSA1 if the first component is a short 873 * decimal number. 874 */ 875 if (lineinfo.keytype == KEY_UNSPEC && l < 8 && 876 strspn(ktype, "0123456789") == l) 877 goto bad; 878 879 /* 880 * Check that something other than whitespace follows 881 * the key type. This won't catch all corruption, but 882 * it does catch trivial truncation. 883 */ 884 cp2 += l; /* Skip past key type */ 885 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 886 ; 887 if (*cp2 == '\0' || *cp2 == '#') { 888 debug2("%s:%ld: truncated after key type", 889 path, linenum); 890 lineinfo.keytype = KEY_UNSPEC; 891 } 892 if (lineinfo.keytype == KEY_UNSPEC) { 893 bad: 894 sshkey_free(lineinfo.key); 895 lineinfo.key = NULL; 896 lineinfo.status = HKF_STATUS_INVALID; 897 if ((r = callback(&lineinfo, ctx)) != 0) 898 break; 899 continue; 900 } 901 } 902 if ((r = callback(&lineinfo, ctx)) != 0) 903 break; 904 } 905 sshkey_free(lineinfo.key); 906 free(lineinfo.line); 907 free(line); 908 return r; 909 } 910 911 int 912 hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx, 913 const char *host, const char *ip, u_int options, u_int note) 914 { 915 FILE *f; 916 int r, oerrno; 917 918 if ((f = fopen(path, "r")) == NULL) 919 return SSH_ERR_SYSTEM_ERROR; 920 921 debug3_f("reading file \"%s\"", path); 922 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip, 923 options, note); 924 oerrno = errno; 925 fclose(f); 926 errno = oerrno; 927 return r; 928 } 929