1 /* $OpenBSD: hostfile.c,v 1.87 2020/12/20 23:36:51 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 63 struct hostkeys { 64 struct hostkey_entry *entries; 65 u_int num_entries; 66 }; 67 68 /* XXX hmac is too easy to dictionary attack; use bcrypt? */ 69 70 static int 71 extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len) 72 { 73 char *p, *b64salt; 74 u_int b64len; 75 int ret; 76 77 if (l < sizeof(HASH_MAGIC) - 1) { 78 debug2("extract_salt: string too short"); 79 return (-1); 80 } 81 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { 82 debug2("extract_salt: invalid magic identifier"); 83 return (-1); 84 } 85 s += sizeof(HASH_MAGIC) - 1; 86 l -= sizeof(HASH_MAGIC) - 1; 87 if ((p = memchr(s, HASH_DELIM, l)) == NULL) { 88 debug2("extract_salt: missing salt termination character"); 89 return (-1); 90 } 91 92 b64len = p - s; 93 /* Sanity check */ 94 if (b64len == 0 || b64len > 1024) { 95 debug2("extract_salt: bad encoded salt length %u", b64len); 96 return (-1); 97 } 98 b64salt = xmalloc(1 + b64len); 99 memcpy(b64salt, s, b64len); 100 b64salt[b64len] = '\0'; 101 102 ret = __b64_pton(b64salt, salt, salt_len); 103 free(b64salt); 104 if (ret == -1) { 105 debug2("extract_salt: salt decode error"); 106 return (-1); 107 } 108 if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) { 109 debug2("extract_salt: expected salt len %zd, got %d", 110 ssh_hmac_bytes(SSH_DIGEST_SHA1), ret); 111 return (-1); 112 } 113 114 return (0); 115 } 116 117 char * 118 host_hash(const char *host, const char *name_from_hostfile, u_int src_len) 119 { 120 struct ssh_hmac_ctx *ctx; 121 u_char salt[256], result[256]; 122 char uu_salt[512], uu_result[512]; 123 static char encoded[1024]; 124 u_int len; 125 126 len = ssh_digest_bytes(SSH_DIGEST_SHA1); 127 128 if (name_from_hostfile == NULL) { 129 /* Create new salt */ 130 arc4random_buf(salt, len); 131 } else { 132 /* Extract salt from known host entry */ 133 if (extract_salt(name_from_hostfile, src_len, salt, 134 sizeof(salt)) == -1) 135 return (NULL); 136 } 137 138 if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || 139 ssh_hmac_init(ctx, salt, len) < 0 || 140 ssh_hmac_update(ctx, host, strlen(host)) < 0 || 141 ssh_hmac_final(ctx, result, sizeof(result))) 142 fatal_f("ssh_hmac failed"); 143 ssh_hmac_free(ctx); 144 145 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || 146 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) 147 fatal_f("__b64_ntop failed"); 148 149 snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, 150 HASH_DELIM, uu_result); 151 152 return (encoded); 153 } 154 155 /* 156 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the 157 * pointer over the key. Skips any whitespace at the beginning and at end. 158 */ 159 160 int 161 hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret) 162 { 163 char *cp; 164 165 /* Skip leading whitespace. */ 166 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) 167 ; 168 169 if (sshkey_read(ret, &cp) != 0) 170 return 0; 171 172 /* Skip trailing whitespace. */ 173 for (; *cp == ' ' || *cp == '\t'; cp++) 174 ; 175 176 /* Return results. */ 177 *cpp = cp; 178 if (bitsp != NULL) 179 *bitsp = sshkey_size(ret); 180 return 1; 181 } 182 183 static HostkeyMarker 184 check_markers(char **cpp) 185 { 186 char marker[32], *sp, *cp = *cpp; 187 int ret = MRK_NONE; 188 189 while (*cp == '@') { 190 /* Only one marker is allowed */ 191 if (ret != MRK_NONE) 192 return MRK_ERROR; 193 /* Markers are terminated by whitespace */ 194 if ((sp = strchr(cp, ' ')) == NULL && 195 (sp = strchr(cp, '\t')) == NULL) 196 return MRK_ERROR; 197 /* Extract marker for comparison */ 198 if (sp <= cp + 1 || sp >= cp + sizeof(marker)) 199 return MRK_ERROR; 200 memcpy(marker, cp, sp - cp); 201 marker[sp - cp] = '\0'; 202 if (strcmp(marker, CA_MARKER) == 0) 203 ret = MRK_CA; 204 else if (strcmp(marker, REVOKE_MARKER) == 0) 205 ret = MRK_REVOKE; 206 else 207 return MRK_ERROR; 208 209 /* Skip past marker and any whitespace that follows it */ 210 cp = sp; 211 for (; *cp == ' ' || *cp == '\t'; cp++) 212 ; 213 } 214 *cpp = cp; 215 return ret; 216 } 217 218 struct hostkeys * 219 init_hostkeys(void) 220 { 221 struct hostkeys *ret = xcalloc(1, sizeof(*ret)); 222 223 ret->entries = NULL; 224 return ret; 225 } 226 227 struct load_callback_ctx { 228 const char *host; 229 u_long num_loaded; 230 struct hostkeys *hostkeys; 231 }; 232 233 static int 234 record_hostkey(struct hostkey_foreach_line *l, void *_ctx) 235 { 236 struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx; 237 struct hostkeys *hostkeys = ctx->hostkeys; 238 struct hostkey_entry *tmp; 239 240 if (l->status == HKF_STATUS_INVALID) { 241 /* XXX make this verbose() in the future */ 242 debug("%s:%ld: parse error in hostkeys file", 243 l->path, l->linenum); 244 return 0; 245 } 246 247 debug3_f("found %skey type %s in file %s:%lu", 248 l->marker == MRK_NONE ? "" : 249 (l->marker == MRK_CA ? "ca " : "revoked "), 250 sshkey_type(l->key), l->path, l->linenum); 251 if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries, 252 hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL) 253 return SSH_ERR_ALLOC_FAIL; 254 hostkeys->entries = tmp; 255 hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host); 256 hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path); 257 hostkeys->entries[hostkeys->num_entries].line = l->linenum; 258 hostkeys->entries[hostkeys->num_entries].key = l->key; 259 l->key = NULL; /* steal it */ 260 hostkeys->entries[hostkeys->num_entries].marker = l->marker; 261 hostkeys->entries[hostkeys->num_entries].note = l->note; 262 hostkeys->num_entries++; 263 ctx->num_loaded++; 264 265 return 0; 266 } 267 268 void 269 load_hostkeys_file(struct hostkeys *hostkeys, const char *host, 270 const char *path, FILE *f, u_int note) 271 { 272 int r; 273 struct load_callback_ctx ctx; 274 275 ctx.host = host; 276 ctx.num_loaded = 0; 277 ctx.hostkeys = hostkeys; 278 279 if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host, 280 NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) { 281 if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT) 282 debug_fr(r, "hostkeys_foreach failed for %s", path); 283 } 284 if (ctx.num_loaded != 0) 285 debug3_f("loaded %lu keys from %s", ctx.num_loaded, host); 286 } 287 288 void 289 load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path, 290 u_int note) 291 { 292 FILE *f; 293 294 if ((f = fopen(path, "r")) == NULL) { 295 debug_f("fopen %s: %s", path, strerror(errno)); 296 return; 297 } 298 299 load_hostkeys_file(hostkeys, host, path, f, note); 300 fclose(f); 301 } 302 303 void 304 free_hostkeys(struct hostkeys *hostkeys) 305 { 306 u_int i; 307 308 for (i = 0; i < hostkeys->num_entries; i++) { 309 free(hostkeys->entries[i].host); 310 free(hostkeys->entries[i].file); 311 sshkey_free(hostkeys->entries[i].key); 312 explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); 313 } 314 free(hostkeys->entries); 315 freezero(hostkeys, sizeof(*hostkeys)); 316 } 317 318 static int 319 check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k) 320 { 321 int is_cert = sshkey_is_cert(k); 322 u_int i; 323 324 for (i = 0; i < hostkeys->num_entries; i++) { 325 if (hostkeys->entries[i].marker != MRK_REVOKE) 326 continue; 327 if (sshkey_equal_public(k, hostkeys->entries[i].key)) 328 return -1; 329 if (is_cert && k != NULL && 330 sshkey_equal_public(k->cert->signature_key, 331 hostkeys->entries[i].key)) 332 return -1; 333 } 334 return 0; 335 } 336 337 /* 338 * Match keys against a specified key, or look one up by key type. 339 * 340 * If looking for a keytype (key == NULL) and one is found then return 341 * HOST_FOUND, otherwise HOST_NEW. 342 * 343 * If looking for a key (key != NULL): 344 * 1. If the key is a cert and a matching CA is found, return HOST_OK 345 * 2. If the key is not a cert and a matching key is found, return HOST_OK 346 * 3. If no key matches but a key with a different type is found, then 347 * return HOST_CHANGED 348 * 4. If no matching keys are found, then return HOST_NEW. 349 * 350 * Finally, check any found key is not revoked. 351 */ 352 static HostStatus 353 check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, 354 struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found) 355 { 356 u_int i; 357 HostStatus end_return = HOST_NEW; 358 int want_cert = sshkey_is_cert(k); 359 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; 360 361 if (found != NULL) 362 *found = NULL; 363 364 for (i = 0; i < hostkeys->num_entries; i++) { 365 if (hostkeys->entries[i].marker != want_marker) 366 continue; 367 if (k == NULL) { 368 if (hostkeys->entries[i].key->type != keytype) 369 continue; 370 if (nid != -1 && 371 sshkey_type_plain(keytype) == KEY_ECDSA && 372 hostkeys->entries[i].key->ecdsa_nid != nid) 373 continue; 374 end_return = HOST_FOUND; 375 if (found != NULL) 376 *found = hostkeys->entries + i; 377 k = hostkeys->entries[i].key; 378 break; 379 } 380 if (want_cert) { 381 if (sshkey_equal_public(k->cert->signature_key, 382 hostkeys->entries[i].key)) { 383 /* A matching CA exists */ 384 end_return = HOST_OK; 385 if (found != NULL) 386 *found = hostkeys->entries + i; 387 break; 388 } 389 } else { 390 if (sshkey_equal(k, hostkeys->entries[i].key)) { 391 end_return = HOST_OK; 392 if (found != NULL) 393 *found = hostkeys->entries + i; 394 break; 395 } 396 /* A non-maching key exists */ 397 end_return = HOST_CHANGED; 398 if (found != NULL) 399 *found = hostkeys->entries + i; 400 } 401 } 402 if (check_key_not_revoked(hostkeys, k) != 0) { 403 end_return = HOST_REVOKED; 404 if (found != NULL) 405 *found = NULL; 406 } 407 return end_return; 408 } 409 410 HostStatus 411 check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key, 412 const struct hostkey_entry **found) 413 { 414 if (key == NULL) 415 fatal("no key to look up"); 416 return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found); 417 } 418 419 int 420 lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid, 421 const struct hostkey_entry **found) 422 { 423 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid, 424 found) == HOST_FOUND); 425 } 426 427 int 428 lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker) 429 { 430 u_int i; 431 432 for (i = 0; i < hostkeys->num_entries; i++) { 433 if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker) 434 return 1; 435 } 436 return 0; 437 } 438 439 static int 440 write_host_entry(FILE *f, const char *host, const char *ip, 441 const struct sshkey *key, int store_hash) 442 { 443 int r, success = 0; 444 char *hashed_host = NULL, *lhost; 445 446 lhost = xstrdup(host); 447 lowercase(lhost); 448 449 if (store_hash) { 450 if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) { 451 error_f("host_hash failed"); 452 free(lhost); 453 return 0; 454 } 455 fprintf(f, "%s ", hashed_host); 456 } else if (ip != NULL) 457 fprintf(f, "%s,%s ", lhost, ip); 458 else { 459 fprintf(f, "%s ", lhost); 460 } 461 free(lhost); 462 if ((r = sshkey_write(key, f)) == 0) 463 success = 1; 464 else 465 error_fr(r, "sshkey_write"); 466 fputc('\n', f); 467 /* If hashing is enabled, the IP address needs to go on its own line */ 468 if (success && store_hash && ip != NULL) 469 success = write_host_entry(f, ip, NULL, key, 1); 470 return success; 471 } 472 473 /* 474 * Create user ~/.ssh directory if it doesn't exist and we want to write to it. 475 * If notify is set, a message will be emitted if the directory is created. 476 */ 477 void 478 hostfile_create_user_ssh_dir(const char *filename, int notify) 479 { 480 char *dotsshdir = NULL, *p; 481 size_t len; 482 struct stat st; 483 484 if ((p = strrchr(filename, '/')) == NULL) 485 return; 486 len = p - filename; 487 dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid()); 488 if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0) 489 goto out; /* not ~/.ssh prefixed */ 490 if (stat(dotsshdir, &st) == 0) 491 goto out; /* dir already exists */ 492 else if (errno != ENOENT) 493 error("Could not stat %s: %s", dotsshdir, strerror(errno)); 494 else { 495 if (mkdir(dotsshdir, 0700) == -1) 496 error("Could not create directory '%.200s' (%s).", 497 dotsshdir, strerror(errno)); 498 else if (notify) 499 logit("Created directory '%s'.", dotsshdir); 500 } 501 out: 502 free(dotsshdir); 503 } 504 505 506 /* 507 * Appends an entry to the host file. Returns false if the entry could not 508 * be appended. 509 */ 510 int 511 add_host_to_hostfile(const char *filename, const char *host, 512 const struct sshkey *key, int store_hash) 513 { 514 FILE *f; 515 int success; 516 517 if (key == NULL) 518 return 1; /* XXX ? */ 519 hostfile_create_user_ssh_dir(filename, 0); 520 f = fopen(filename, "a"); 521 if (!f) 522 return 0; 523 success = write_host_entry(f, host, NULL, key, store_hash); 524 fclose(f); 525 return success; 526 } 527 528 struct host_delete_ctx { 529 FILE *out; 530 int quiet; 531 const char *host, *ip; 532 u_int *match_keys; /* mask of HKF_MATCH_* for this key */ 533 struct sshkey * const *keys; 534 size_t nkeys; 535 int modified; 536 }; 537 538 static int 539 host_delete(struct hostkey_foreach_line *l, void *_ctx) 540 { 541 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx; 542 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 543 size_t i; 544 545 /* Don't remove CA and revocation lines */ 546 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) { 547 /* 548 * If this line contains one of the keys that we will be 549 * adding later, then don't change it and mark the key for 550 * skipping. 551 */ 552 for (i = 0; i < ctx->nkeys; i++) { 553 if (!sshkey_equal(ctx->keys[i], l->key)) 554 continue; 555 ctx->match_keys[i] |= l->match; 556 fprintf(ctx->out, "%s\n", l->line); 557 debug3_f("%s key already at %s:%ld", 558 sshkey_type(l->key), l->path, l->linenum); 559 return 0; 560 } 561 562 /* 563 * Hostname matches and has no CA/revoke marker, delete it 564 * by *not* writing the line to ctx->out. 565 */ 566 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s", 567 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 568 l->path, l->linenum, sshkey_type(l->key), ctx->host); 569 ctx->modified = 1; 570 return 0; 571 } 572 /* Retain non-matching hosts and invalid lines when deleting */ 573 if (l->status == HKF_STATUS_INVALID) { 574 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry", 575 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 576 l->path, l->linenum); 577 } 578 fprintf(ctx->out, "%s\n", l->line); 579 return 0; 580 } 581 582 int 583 hostfile_replace_entries(const char *filename, const char *host, const char *ip, 584 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg) 585 { 586 int r, fd, oerrno = 0; 587 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 588 struct host_delete_ctx ctx; 589 char *fp, *temp = NULL, *back = NULL; 590 const char *what; 591 mode_t omask; 592 size_t i; 593 u_int want; 594 595 omask = umask(077); 596 597 memset(&ctx, 0, sizeof(ctx)); 598 ctx.host = host; 599 ctx.ip = ip; 600 ctx.quiet = quiet; 601 602 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL) 603 return SSH_ERR_ALLOC_FAIL; 604 ctx.keys = keys; 605 ctx.nkeys = nkeys; 606 ctx.modified = 0; 607 608 /* 609 * Prepare temporary file for in-place deletion. 610 */ 611 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 || 612 (r = asprintf(&back, "%s.old", filename)) == -1) { 613 r = SSH_ERR_ALLOC_FAIL; 614 goto fail; 615 } 616 617 if ((fd = mkstemp(temp)) == -1) { 618 oerrno = errno; 619 error_f("mkstemp: %s", strerror(oerrno)); 620 r = SSH_ERR_SYSTEM_ERROR; 621 goto fail; 622 } 623 if ((ctx.out = fdopen(fd, "w")) == NULL) { 624 oerrno = errno; 625 close(fd); 626 error_f("fdopen: %s", strerror(oerrno)); 627 r = SSH_ERR_SYSTEM_ERROR; 628 goto fail; 629 } 630 631 /* Remove stale/mismatching entries for the specified host */ 632 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip, 633 HKF_WANT_PARSE_KEY, 0)) != 0) { 634 oerrno = errno; 635 error_fr(r, "hostkeys_foreach"); 636 goto fail; 637 } 638 639 /* Re-add the requested keys */ 640 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP); 641 for (i = 0; i < nkeys; i++) { 642 if ((want & ctx.match_keys[i]) == want) 643 continue; 644 if ((fp = sshkey_fingerprint(keys[i], hash_alg, 645 SSH_FP_DEFAULT)) == NULL) { 646 r = SSH_ERR_ALLOC_FAIL; 647 goto fail; 648 } 649 /* write host/ip */ 650 what = ""; 651 if (ctx.match_keys[i] == 0) { 652 what = "Adding new key"; 653 if (!write_host_entry(ctx.out, host, ip, 654 keys[i], store_hash)) { 655 r = SSH_ERR_INTERNAL_ERROR; 656 goto fail; 657 } 658 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) { 659 what = "Fixing match (hostname)"; 660 if (!write_host_entry(ctx.out, host, NULL, 661 keys[i], store_hash)) { 662 r = SSH_ERR_INTERNAL_ERROR; 663 goto fail; 664 } 665 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) { 666 what = "Fixing match (address)"; 667 if (!write_host_entry(ctx.out, ip, NULL, 668 keys[i], store_hash)) { 669 r = SSH_ERR_INTERNAL_ERROR; 670 goto fail; 671 } 672 } 673 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s", 674 quiet ? __func__ : "", quiet ? ": " : "", what, 675 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename, 676 sshkey_ssh_name(keys[i]), fp); 677 free(fp); 678 ctx.modified = 1; 679 } 680 fclose(ctx.out); 681 ctx.out = NULL; 682 683 if (ctx.modified) { 684 /* Backup the original file and replace it with the temporary */ 685 if (unlink(back) == -1 && errno != ENOENT) { 686 oerrno = errno; 687 error_f("unlink %.100s: %s", back, strerror(errno)); 688 r = SSH_ERR_SYSTEM_ERROR; 689 goto fail; 690 } 691 if (link(filename, back) == -1) { 692 oerrno = errno; 693 error_f("link %.100s to %.100s: %s", filename, 694 back, strerror(errno)); 695 r = SSH_ERR_SYSTEM_ERROR; 696 goto fail; 697 } 698 if (rename(temp, filename) == -1) { 699 oerrno = errno; 700 error_f("rename \"%s\" to \"%s\": %s", temp, 701 filename, strerror(errno)); 702 r = SSH_ERR_SYSTEM_ERROR; 703 goto fail; 704 } 705 } else { 706 /* No changes made; just delete the temporary file */ 707 if (unlink(temp) != 0) 708 error_f("unlink \"%s\": %s", temp, strerror(errno)); 709 } 710 711 /* success */ 712 r = 0; 713 fail: 714 if (temp != NULL && r != 0) 715 unlink(temp); 716 free(temp); 717 free(back); 718 if (ctx.out != NULL) 719 fclose(ctx.out); 720 free(ctx.match_keys); 721 umask(omask); 722 if (r == SSH_ERR_SYSTEM_ERROR) 723 errno = oerrno; 724 return r; 725 } 726 727 static int 728 match_maybe_hashed(const char *host, const char *names, int *was_hashed) 729 { 730 int hashed = *names == HASH_DELIM; 731 const char *hashed_host; 732 size_t nlen = strlen(names); 733 734 if (was_hashed != NULL) 735 *was_hashed = hashed; 736 if (hashed) { 737 if ((hashed_host = host_hash(host, names, nlen)) == NULL) 738 return -1; 739 return nlen == strlen(hashed_host) && 740 strncmp(hashed_host, names, nlen) == 0; 741 } 742 return match_hostname(host, names) == 1; 743 } 744 745 int 746 hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback, 747 void *ctx, const char *host, const char *ip, u_int options, u_int note) 748 { 749 char *line = NULL, ktype[128]; 750 u_long linenum = 0; 751 char *cp, *cp2; 752 u_int kbits; 753 int hashed; 754 int s, r = 0; 755 struct hostkey_foreach_line lineinfo; 756 size_t linesize = 0, l; 757 758 memset(&lineinfo, 0, sizeof(lineinfo)); 759 if (host == NULL && (options & HKF_WANT_MATCH) != 0) 760 return SSH_ERR_INVALID_ARGUMENT; 761 762 while (getline(&line, &linesize, f) != -1) { 763 linenum++; 764 line[strcspn(line, "\n")] = '\0'; 765 766 free(lineinfo.line); 767 sshkey_free(lineinfo.key); 768 memset(&lineinfo, 0, sizeof(lineinfo)); 769 lineinfo.path = path; 770 lineinfo.linenum = linenum; 771 lineinfo.line = xstrdup(line); 772 lineinfo.marker = MRK_NONE; 773 lineinfo.status = HKF_STATUS_OK; 774 lineinfo.keytype = KEY_UNSPEC; 775 lineinfo.note = note; 776 777 /* Skip any leading whitespace, comments and empty lines. */ 778 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 779 ; 780 if (!*cp || *cp == '#' || *cp == '\n') { 781 if ((options & HKF_WANT_MATCH) == 0) { 782 lineinfo.status = HKF_STATUS_COMMENT; 783 if ((r = callback(&lineinfo, ctx)) != 0) 784 break; 785 } 786 continue; 787 } 788 789 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) { 790 verbose_f("invalid marker at %s:%lu", path, linenum); 791 if ((options & HKF_WANT_MATCH) == 0) 792 goto bad; 793 continue; 794 } 795 796 /* Find the end of the host name portion. */ 797 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) 798 ; 799 lineinfo.hosts = cp; 800 *cp2++ = '\0'; 801 802 /* Check if the host name matches. */ 803 if (host != NULL) { 804 if ((s = match_maybe_hashed(host, lineinfo.hosts, 805 &hashed)) == -1) { 806 debug2_f("%s:%ld: bad host hash \"%.32s\"", 807 path, linenum, lineinfo.hosts); 808 goto bad; 809 } 810 if (s == 1) { 811 lineinfo.status = HKF_STATUS_MATCHED; 812 lineinfo.match |= HKF_MATCH_HOST | 813 (hashed ? HKF_MATCH_HOST_HASHED : 0); 814 } 815 /* Try matching IP address if supplied */ 816 if (ip != NULL) { 817 if ((s = match_maybe_hashed(ip, lineinfo.hosts, 818 &hashed)) == -1) { 819 debug2_f("%s:%ld: bad ip hash " 820 "\"%.32s\"", path, linenum, 821 lineinfo.hosts); 822 goto bad; 823 } 824 if (s == 1) { 825 lineinfo.status = HKF_STATUS_MATCHED; 826 lineinfo.match |= HKF_MATCH_IP | 827 (hashed ? HKF_MATCH_IP_HASHED : 0); 828 } 829 } 830 /* 831 * Skip this line if host matching requested and 832 * neither host nor address matched. 833 */ 834 if ((options & HKF_WANT_MATCH) != 0 && 835 lineinfo.status != HKF_STATUS_MATCHED) 836 continue; 837 } 838 839 /* Got a match. Skip host name and any following whitespace */ 840 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 841 ; 842 if (*cp2 == '\0' || *cp2 == '#') { 843 debug2("%s:%ld: truncated before key type", 844 path, linenum); 845 goto bad; 846 } 847 lineinfo.rawkey = cp = cp2; 848 849 if ((options & HKF_WANT_PARSE_KEY) != 0) { 850 /* 851 * Extract the key from the line. This will skip 852 * any leading whitespace. Ignore badly formatted 853 * lines. 854 */ 855 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) { 856 error_f("sshkey_new failed"); 857 r = SSH_ERR_ALLOC_FAIL; 858 break; 859 } 860 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) { 861 goto bad; 862 } 863 lineinfo.keytype = lineinfo.key->type; 864 lineinfo.comment = cp; 865 } else { 866 /* Extract and parse key type */ 867 l = strcspn(lineinfo.rawkey, " \t"); 868 if (l <= 1 || l >= sizeof(ktype) || 869 lineinfo.rawkey[l] == '\0') 870 goto bad; 871 memcpy(ktype, lineinfo.rawkey, l); 872 ktype[l] = '\0'; 873 lineinfo.keytype = sshkey_type_from_name(ktype); 874 875 /* 876 * Assume legacy RSA1 if the first component is a short 877 * decimal number. 878 */ 879 if (lineinfo.keytype == KEY_UNSPEC && l < 8 && 880 strspn(ktype, "0123456789") == l) 881 goto bad; 882 883 /* 884 * Check that something other than whitespace follows 885 * the key type. This won't catch all corruption, but 886 * it does catch trivial truncation. 887 */ 888 cp2 += l; /* Skip past key type */ 889 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 890 ; 891 if (*cp2 == '\0' || *cp2 == '#') { 892 debug2("%s:%ld: truncated after key type", 893 path, linenum); 894 lineinfo.keytype = KEY_UNSPEC; 895 } 896 if (lineinfo.keytype == KEY_UNSPEC) { 897 bad: 898 sshkey_free(lineinfo.key); 899 lineinfo.key = NULL; 900 lineinfo.status = HKF_STATUS_INVALID; 901 if ((r = callback(&lineinfo, ctx)) != 0) 902 break; 903 continue; 904 } 905 } 906 if ((r = callback(&lineinfo, ctx)) != 0) 907 break; 908 } 909 sshkey_free(lineinfo.key); 910 free(lineinfo.line); 911 free(line); 912 return r; 913 } 914 915 int 916 hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx, 917 const char *host, const char *ip, u_int options, u_int note) 918 { 919 FILE *f; 920 int r, oerrno; 921 922 if ((f = fopen(path, "r")) == NULL) 923 return SSH_ERR_SYSTEM_ERROR; 924 925 debug3_f("reading file \"%s\"", path); 926 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip, 927 options, note); 928 oerrno = errno; 929 fclose(f); 930 errno = oerrno; 931 return r; 932 } 933