1 /* $OpenBSD: hostfile.c,v 1.93 2022/01/06 22:02:52 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 "includes.h" 40 41 #include <sys/types.h> 42 #include <sys/stat.h> 43 44 #include <netinet/in.h> 45 46 #include <errno.h> 47 #include <resolv.h> 48 #include <stdarg.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 54 #include "xmalloc.h" 55 #include "match.h" 56 #include "sshkey.h" 57 #include "hostfile.h" 58 #include "log.h" 59 #include "misc.h" 60 #include "pathnames.h" 61 #include "ssherr.h" 62 #include "digest.h" 63 #include "hmac.h" 64 #include "sshbuf.h" 65 66 /* XXX hmac is too easy to dictionary attack; use bcrypt? */ 67 68 static int 69 extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len) 70 { 71 char *p, *b64salt; 72 u_int b64len; 73 int ret; 74 75 if (l < sizeof(HASH_MAGIC) - 1) { 76 debug2("extract_salt: string too short"); 77 return (-1); 78 } 79 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { 80 debug2("extract_salt: invalid magic identifier"); 81 return (-1); 82 } 83 s += sizeof(HASH_MAGIC) - 1; 84 l -= sizeof(HASH_MAGIC) - 1; 85 if ((p = memchr(s, HASH_DELIM, l)) == NULL) { 86 debug2("extract_salt: missing salt termination character"); 87 return (-1); 88 } 89 90 b64len = p - s; 91 /* Sanity check */ 92 if (b64len == 0 || b64len > 1024) { 93 debug2("extract_salt: bad encoded salt length %u", b64len); 94 return (-1); 95 } 96 b64salt = xmalloc(1 + b64len); 97 memcpy(b64salt, s, b64len); 98 b64salt[b64len] = '\0'; 99 100 ret = __b64_pton(b64salt, salt, salt_len); 101 free(b64salt); 102 if (ret == -1) { 103 debug2("extract_salt: salt decode error"); 104 return (-1); 105 } 106 if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) { 107 debug2("extract_salt: expected salt len %zd, got %d", 108 ssh_hmac_bytes(SSH_DIGEST_SHA1), ret); 109 return (-1); 110 } 111 112 return (0); 113 } 114 115 char * 116 host_hash(const char *host, const char *name_from_hostfile, u_int src_len) 117 { 118 struct ssh_hmac_ctx *ctx; 119 u_char salt[256], result[256]; 120 char uu_salt[512], uu_result[512]; 121 char *encoded = NULL; 122 u_int len; 123 124 len = ssh_digest_bytes(SSH_DIGEST_SHA1); 125 126 if (name_from_hostfile == NULL) { 127 /* Create new salt */ 128 arc4random_buf(salt, len); 129 } else { 130 /* Extract salt from known host entry */ 131 if (extract_salt(name_from_hostfile, src_len, salt, 132 sizeof(salt)) == -1) 133 return (NULL); 134 } 135 136 if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || 137 ssh_hmac_init(ctx, salt, len) < 0 || 138 ssh_hmac_update(ctx, host, strlen(host)) < 0 || 139 ssh_hmac_final(ctx, result, sizeof(result))) 140 fatal_f("ssh_hmac failed"); 141 ssh_hmac_free(ctx); 142 143 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || 144 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) 145 fatal_f("__b64_ntop failed"); 146 xasprintf(&encoded, "%s%s%c%s", HASH_MAGIC, uu_salt, HASH_DELIM, 147 uu_result); 148 149 return (encoded); 150 } 151 152 /* 153 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the 154 * pointer over the key. Skips any whitespace at the beginning and at end. 155 */ 156 157 int 158 hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret) 159 { 160 char *cp; 161 162 /* Skip leading whitespace. */ 163 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) 164 ; 165 166 if (sshkey_read(ret, &cp) != 0) 167 return 0; 168 169 /* Skip trailing whitespace. */ 170 for (; *cp == ' ' || *cp == '\t'; cp++) 171 ; 172 173 /* Return results. */ 174 *cpp = cp; 175 if (bitsp != NULL) 176 *bitsp = sshkey_size(ret); 177 return 1; 178 } 179 180 static HostkeyMarker 181 check_markers(char **cpp) 182 { 183 char marker[32], *sp, *cp = *cpp; 184 int ret = MRK_NONE; 185 186 while (*cp == '@') { 187 /* Only one marker is allowed */ 188 if (ret != MRK_NONE) 189 return MRK_ERROR; 190 /* Markers are terminated by whitespace */ 191 if ((sp = strchr(cp, ' ')) == NULL && 192 (sp = strchr(cp, '\t')) == NULL) 193 return MRK_ERROR; 194 /* Extract marker for comparison */ 195 if (sp <= cp + 1 || sp >= cp + sizeof(marker)) 196 return MRK_ERROR; 197 memcpy(marker, cp, sp - cp); 198 marker[sp - cp] = '\0'; 199 if (strcmp(marker, CA_MARKER) == 0) 200 ret = MRK_CA; 201 else if (strcmp(marker, REVOKE_MARKER) == 0) 202 ret = MRK_REVOKE; 203 else 204 return MRK_ERROR; 205 206 /* Skip past marker and any whitespace that follows it */ 207 cp = sp; 208 for (; *cp == ' ' || *cp == '\t'; cp++) 209 ; 210 } 211 *cpp = cp; 212 return ret; 213 } 214 215 struct hostkeys * 216 init_hostkeys(void) 217 { 218 struct hostkeys *ret = xcalloc(1, sizeof(*ret)); 219 220 ret->entries = NULL; 221 return ret; 222 } 223 224 struct load_callback_ctx { 225 const char *host; 226 u_long num_loaded; 227 struct hostkeys *hostkeys; 228 }; 229 230 static int 231 record_hostkey(struct hostkey_foreach_line *l, void *_ctx) 232 { 233 struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx; 234 struct hostkeys *hostkeys = ctx->hostkeys; 235 struct hostkey_entry *tmp; 236 237 if (l->status == HKF_STATUS_INVALID) { 238 /* XXX make this verbose() in the future */ 239 debug("%s:%ld: parse error in hostkeys file", 240 l->path, l->linenum); 241 return 0; 242 } 243 244 debug3_f("found %skey type %s in file %s:%lu", 245 l->marker == MRK_NONE ? "" : 246 (l->marker == MRK_CA ? "ca " : "revoked "), 247 sshkey_type(l->key), l->path, l->linenum); 248 if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries, 249 hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL) 250 return SSH_ERR_ALLOC_FAIL; 251 hostkeys->entries = tmp; 252 hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host); 253 hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path); 254 hostkeys->entries[hostkeys->num_entries].line = l->linenum; 255 hostkeys->entries[hostkeys->num_entries].key = l->key; 256 l->key = NULL; /* steal it */ 257 hostkeys->entries[hostkeys->num_entries].marker = l->marker; 258 hostkeys->entries[hostkeys->num_entries].note = l->note; 259 hostkeys->num_entries++; 260 ctx->num_loaded++; 261 262 return 0; 263 } 264 265 void 266 load_hostkeys_file(struct hostkeys *hostkeys, const char *host, 267 const char *path, FILE *f, u_int note) 268 { 269 int r; 270 struct load_callback_ctx ctx; 271 272 ctx.host = host; 273 ctx.num_loaded = 0; 274 ctx.hostkeys = hostkeys; 275 276 if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host, 277 NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) { 278 if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT) 279 debug_fr(r, "hostkeys_foreach failed for %s", path); 280 } 281 if (ctx.num_loaded != 0) 282 debug3_f("loaded %lu keys from %s", ctx.num_loaded, host); 283 } 284 285 void 286 load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path, 287 u_int note) 288 { 289 FILE *f; 290 291 if ((f = fopen(path, "r")) == NULL) { 292 debug_f("fopen %s: %s", path, strerror(errno)); 293 return; 294 } 295 296 load_hostkeys_file(hostkeys, host, path, f, note); 297 fclose(f); 298 } 299 300 void 301 free_hostkeys(struct hostkeys *hostkeys) 302 { 303 u_int i; 304 305 for (i = 0; i < hostkeys->num_entries; i++) { 306 free(hostkeys->entries[i].host); 307 free(hostkeys->entries[i].file); 308 sshkey_free(hostkeys->entries[i].key); 309 explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); 310 } 311 free(hostkeys->entries); 312 freezero(hostkeys, sizeof(*hostkeys)); 313 } 314 315 static int 316 check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k) 317 { 318 int is_cert = sshkey_is_cert(k); 319 u_int i; 320 321 for (i = 0; i < hostkeys->num_entries; i++) { 322 if (hostkeys->entries[i].marker != MRK_REVOKE) 323 continue; 324 if (sshkey_equal_public(k, hostkeys->entries[i].key)) 325 return -1; 326 if (is_cert && k != NULL && 327 sshkey_equal_public(k->cert->signature_key, 328 hostkeys->entries[i].key)) 329 return -1; 330 } 331 return 0; 332 } 333 334 /* 335 * Match keys against a specified key, or look one up by key type. 336 * 337 * If looking for a keytype (key == NULL) and one is found then return 338 * HOST_FOUND, otherwise HOST_NEW. 339 * 340 * If looking for a key (key != NULL): 341 * 1. If the key is a cert and a matching CA is found, return HOST_OK 342 * 2. If the key is not a cert and a matching key is found, return HOST_OK 343 * 3. If no key matches but a key with a different type is found, then 344 * return HOST_CHANGED 345 * 4. If no matching keys are found, then return HOST_NEW. 346 * 347 * Finally, check any found key is not revoked. 348 */ 349 static HostStatus 350 check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, 351 struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found) 352 { 353 u_int i; 354 HostStatus end_return = HOST_NEW; 355 int want_cert = sshkey_is_cert(k); 356 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; 357 358 if (found != NULL) 359 *found = NULL; 360 361 for (i = 0; i < hostkeys->num_entries; i++) { 362 if (hostkeys->entries[i].marker != want_marker) 363 continue; 364 if (k == NULL) { 365 if (hostkeys->entries[i].key->type != keytype) 366 continue; 367 if (nid != -1 && 368 sshkey_type_plain(keytype) == KEY_ECDSA && 369 hostkeys->entries[i].key->ecdsa_nid != nid) 370 continue; 371 end_return = HOST_FOUND; 372 if (found != NULL) 373 *found = hostkeys->entries + i; 374 k = hostkeys->entries[i].key; 375 break; 376 } 377 if (want_cert) { 378 if (sshkey_equal_public(k->cert->signature_key, 379 hostkeys->entries[i].key)) { 380 /* A matching CA exists */ 381 end_return = HOST_OK; 382 if (found != NULL) 383 *found = hostkeys->entries + i; 384 break; 385 } 386 } else { 387 if (sshkey_equal(k, hostkeys->entries[i].key)) { 388 end_return = HOST_OK; 389 if (found != NULL) 390 *found = hostkeys->entries + i; 391 break; 392 } 393 /* A non-matching key exists */ 394 end_return = HOST_CHANGED; 395 if (found != NULL) 396 *found = hostkeys->entries + i; 397 } 398 } 399 if (check_key_not_revoked(hostkeys, k) != 0) { 400 end_return = HOST_REVOKED; 401 if (found != NULL) 402 *found = NULL; 403 } 404 return end_return; 405 } 406 407 HostStatus 408 check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key, 409 const struct hostkey_entry **found) 410 { 411 if (key == NULL) 412 fatal("no key to look up"); 413 return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found); 414 } 415 416 int 417 lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid, 418 const struct hostkey_entry **found) 419 { 420 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid, 421 found) == HOST_FOUND); 422 } 423 424 int 425 lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker) 426 { 427 u_int i; 428 429 for (i = 0; i < hostkeys->num_entries; i++) { 430 if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker) 431 return 1; 432 } 433 return 0; 434 } 435 436 static int 437 write_host_entry(FILE *f, const char *host, const char *ip, 438 const struct sshkey *key, int store_hash) 439 { 440 int r, success = 0; 441 char *hashed_host = NULL, *lhost; 442 443 lhost = xstrdup(host); 444 lowercase(lhost); 445 446 if (store_hash) { 447 if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) { 448 error_f("host_hash failed"); 449 free(lhost); 450 return 0; 451 } 452 fprintf(f, "%s ", hashed_host); 453 } else if (ip != NULL) 454 fprintf(f, "%s,%s ", lhost, ip); 455 else { 456 fprintf(f, "%s ", lhost); 457 } 458 free(hashed_host); 459 free(lhost); 460 if ((r = sshkey_write(key, f)) == 0) 461 success = 1; 462 else 463 error_fr(r, "sshkey_write"); 464 fputc('\n', f); 465 /* If hashing is enabled, the IP address needs to go on its own line */ 466 if (success && store_hash && ip != NULL) 467 success = write_host_entry(f, ip, NULL, key, 1); 468 return success; 469 } 470 471 /* 472 * Create user ~/.ssh directory if it doesn't exist and we want to write to it. 473 * If notify is set, a message will be emitted if the directory is created. 474 */ 475 void 476 hostfile_create_user_ssh_dir(const char *filename, int notify) 477 { 478 char *dotsshdir = NULL, *p; 479 size_t len; 480 struct stat st; 481 482 if ((p = strrchr(filename, '/')) == NULL) 483 return; 484 len = p - filename; 485 dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid()); 486 if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0) 487 goto out; /* not ~/.ssh prefixed */ 488 if (stat(dotsshdir, &st) == 0) 489 goto out; /* dir already exists */ 490 else if (errno != ENOENT) 491 error("Could not stat %s: %s", dotsshdir, strerror(errno)); 492 else { 493 #ifdef WITH_SELINUX 494 ssh_selinux_setfscreatecon(dotsshdir); 495 #endif 496 if (mkdir(dotsshdir, 0700) == -1) 497 error("Could not create directory '%.200s' (%s).", 498 dotsshdir, strerror(errno)); 499 else if (notify) 500 logit("Created directory '%s'.", dotsshdir); 501 #ifdef WITH_SELINUX 502 ssh_selinux_setfscreatecon(NULL); 503 #endif 504 } 505 out: 506 free(dotsshdir); 507 } 508 509 /* 510 * Appends an entry to the host file. Returns false if the entry could not 511 * be appended. 512 */ 513 int 514 add_host_to_hostfile(const char *filename, const char *host, 515 const struct sshkey *key, int store_hash) 516 { 517 FILE *f; 518 int success; 519 520 if (key == NULL) 521 return 1; /* XXX ? */ 522 hostfile_create_user_ssh_dir(filename, 0); 523 f = fopen(filename, "a"); 524 if (!f) 525 return 0; 526 success = write_host_entry(f, host, NULL, key, store_hash); 527 fclose(f); 528 return success; 529 } 530 531 struct host_delete_ctx { 532 FILE *out; 533 int quiet; 534 const char *host, *ip; 535 u_int *match_keys; /* mask of HKF_MATCH_* for this key */ 536 struct sshkey * const *keys; 537 size_t nkeys; 538 int modified; 539 }; 540 541 static int 542 host_delete(struct hostkey_foreach_line *l, void *_ctx) 543 { 544 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx; 545 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 546 size_t i; 547 548 /* Don't remove CA and revocation lines */ 549 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) { 550 /* 551 * If this line contains one of the keys that we will be 552 * adding later, then don't change it and mark the key for 553 * skipping. 554 */ 555 for (i = 0; i < ctx->nkeys; i++) { 556 if (!sshkey_equal(ctx->keys[i], l->key)) 557 continue; 558 ctx->match_keys[i] |= l->match; 559 fprintf(ctx->out, "%s\n", l->line); 560 debug3_f("%s key already at %s:%ld", 561 sshkey_type(l->key), l->path, l->linenum); 562 return 0; 563 } 564 565 /* 566 * Hostname matches and has no CA/revoke marker, delete it 567 * by *not* writing the line to ctx->out. 568 */ 569 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s", 570 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 571 l->path, l->linenum, sshkey_type(l->key), ctx->host); 572 ctx->modified = 1; 573 return 0; 574 } 575 /* Retain non-matching hosts and invalid lines when deleting */ 576 if (l->status == HKF_STATUS_INVALID) { 577 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry", 578 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 579 l->path, l->linenum); 580 } 581 fprintf(ctx->out, "%s\n", l->line); 582 return 0; 583 } 584 585 int 586 hostfile_replace_entries(const char *filename, const char *host, const char *ip, 587 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg) 588 { 589 int r, fd, oerrno = 0; 590 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 591 struct host_delete_ctx ctx; 592 char *fp, *temp = NULL, *back = NULL; 593 const char *what; 594 mode_t omask; 595 size_t i; 596 u_int want; 597 598 omask = umask(077); 599 600 memset(&ctx, 0, sizeof(ctx)); 601 ctx.host = host; 602 ctx.ip = ip; 603 ctx.quiet = quiet; 604 605 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL) 606 return SSH_ERR_ALLOC_FAIL; 607 ctx.keys = keys; 608 ctx.nkeys = nkeys; 609 ctx.modified = 0; 610 611 /* 612 * Prepare temporary file for in-place deletion. 613 */ 614 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 || 615 (r = asprintf(&back, "%s.old", filename)) == -1) { 616 r = SSH_ERR_ALLOC_FAIL; 617 goto fail; 618 } 619 620 if ((fd = mkstemp(temp)) == -1) { 621 oerrno = errno; 622 error_f("mkstemp: %s", strerror(oerrno)); 623 r = SSH_ERR_SYSTEM_ERROR; 624 goto fail; 625 } 626 if ((ctx.out = fdopen(fd, "w")) == NULL) { 627 oerrno = errno; 628 close(fd); 629 error_f("fdopen: %s", strerror(oerrno)); 630 r = SSH_ERR_SYSTEM_ERROR; 631 goto fail; 632 } 633 634 /* Remove stale/mismatching entries for the specified host */ 635 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip, 636 HKF_WANT_PARSE_KEY, 0)) != 0) { 637 oerrno = errno; 638 error_fr(r, "hostkeys_foreach"); 639 goto fail; 640 } 641 642 /* Re-add the requested keys */ 643 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP); 644 for (i = 0; i < nkeys; i++) { 645 if (keys[i] == NULL || (want & ctx.match_keys[i]) == want) 646 continue; 647 if ((fp = sshkey_fingerprint(keys[i], hash_alg, 648 SSH_FP_DEFAULT)) == NULL) { 649 r = SSH_ERR_ALLOC_FAIL; 650 goto fail; 651 } 652 /* write host/ip */ 653 what = ""; 654 if (ctx.match_keys[i] == 0) { 655 what = "Adding new key"; 656 if (!write_host_entry(ctx.out, host, ip, 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_HOST) { 662 what = "Fixing match (hostname)"; 663 if (!write_host_entry(ctx.out, host, NULL, 664 keys[i], store_hash)) { 665 r = SSH_ERR_INTERNAL_ERROR; 666 goto fail; 667 } 668 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) { 669 what = "Fixing match (address)"; 670 if (!write_host_entry(ctx.out, ip, NULL, 671 keys[i], store_hash)) { 672 r = SSH_ERR_INTERNAL_ERROR; 673 goto fail; 674 } 675 } 676 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s", 677 quiet ? __func__ : "", quiet ? ": " : "", what, 678 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename, 679 sshkey_ssh_name(keys[i]), fp); 680 free(fp); 681 ctx.modified = 1; 682 } 683 fclose(ctx.out); 684 ctx.out = NULL; 685 686 if (ctx.modified) { 687 /* Backup the original file and replace it with the temporary */ 688 if (unlink(back) == -1 && errno != ENOENT) { 689 oerrno = errno; 690 error_f("unlink %.100s: %s", back, strerror(errno)); 691 r = SSH_ERR_SYSTEM_ERROR; 692 goto fail; 693 } 694 if (link(filename, back) == -1) { 695 oerrno = errno; 696 error_f("link %.100s to %.100s: %s", filename, 697 back, strerror(errno)); 698 r = SSH_ERR_SYSTEM_ERROR; 699 goto fail; 700 } 701 if (rename(temp, filename) == -1) { 702 oerrno = errno; 703 error_f("rename \"%s\" to \"%s\": %s", temp, 704 filename, strerror(errno)); 705 r = SSH_ERR_SYSTEM_ERROR; 706 goto fail; 707 } 708 } else { 709 /* No changes made; just delete the temporary file */ 710 if (unlink(temp) != 0) 711 error_f("unlink \"%s\": %s", temp, strerror(errno)); 712 } 713 714 /* success */ 715 r = 0; 716 fail: 717 if (temp != NULL && r != 0) 718 unlink(temp); 719 free(temp); 720 free(back); 721 if (ctx.out != NULL) 722 fclose(ctx.out); 723 free(ctx.match_keys); 724 umask(omask); 725 if (r == SSH_ERR_SYSTEM_ERROR) 726 errno = oerrno; 727 return r; 728 } 729 730 static int 731 match_maybe_hashed(const char *host, const char *names, int *was_hashed) 732 { 733 int hashed = *names == HASH_DELIM, ret; 734 char *hashed_host = NULL; 735 size_t nlen = strlen(names); 736 737 if (was_hashed != NULL) 738 *was_hashed = hashed; 739 if (hashed) { 740 if ((hashed_host = host_hash(host, names, nlen)) == NULL) 741 return -1; 742 ret = (nlen == strlen(hashed_host) && 743 strncmp(hashed_host, names, nlen) == 0); 744 free(hashed_host); 745 return ret; 746 } 747 return match_hostname(host, names) == 1; 748 } 749 750 int 751 hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback, 752 void *ctx, const char *host, const char *ip, u_int options, u_int note) 753 { 754 char *line = NULL, ktype[128]; 755 u_long linenum = 0; 756 char *cp, *cp2; 757 u_int kbits; 758 int hashed; 759 int s, r = 0; 760 struct hostkey_foreach_line lineinfo; 761 size_t linesize = 0, l; 762 763 memset(&lineinfo, 0, sizeof(lineinfo)); 764 if (host == NULL && (options & HKF_WANT_MATCH) != 0) 765 return SSH_ERR_INVALID_ARGUMENT; 766 767 while (getline(&line, &linesize, f) != -1) { 768 linenum++; 769 line[strcspn(line, "\n")] = '\0'; 770 771 free(lineinfo.line); 772 sshkey_free(lineinfo.key); 773 memset(&lineinfo, 0, sizeof(lineinfo)); 774 lineinfo.path = path; 775 lineinfo.linenum = linenum; 776 lineinfo.line = xstrdup(line); 777 lineinfo.marker = MRK_NONE; 778 lineinfo.status = HKF_STATUS_OK; 779 lineinfo.keytype = KEY_UNSPEC; 780 lineinfo.note = note; 781 782 /* Skip any leading whitespace, comments and empty lines. */ 783 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 784 ; 785 if (!*cp || *cp == '#' || *cp == '\n') { 786 if ((options & HKF_WANT_MATCH) == 0) { 787 lineinfo.status = HKF_STATUS_COMMENT; 788 if ((r = callback(&lineinfo, ctx)) != 0) 789 break; 790 } 791 continue; 792 } 793 794 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) { 795 verbose_f("invalid marker at %s:%lu", path, linenum); 796 if ((options & HKF_WANT_MATCH) == 0) 797 goto bad; 798 continue; 799 } 800 801 /* Find the end of the host name portion. */ 802 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) 803 ; 804 lineinfo.hosts = cp; 805 *cp2++ = '\0'; 806 807 /* Check if the host name matches. */ 808 if (host != NULL) { 809 if ((s = match_maybe_hashed(host, lineinfo.hosts, 810 &hashed)) == -1) { 811 debug2_f("%s:%ld: bad host hash \"%.32s\"", 812 path, linenum, lineinfo.hosts); 813 goto bad; 814 } 815 if (s == 1) { 816 lineinfo.status = HKF_STATUS_MATCHED; 817 lineinfo.match |= HKF_MATCH_HOST | 818 (hashed ? HKF_MATCH_HOST_HASHED : 0); 819 } 820 /* Try matching IP address if supplied */ 821 if (ip != NULL) { 822 if ((s = match_maybe_hashed(ip, lineinfo.hosts, 823 &hashed)) == -1) { 824 debug2_f("%s:%ld: bad ip hash " 825 "\"%.32s\"", path, linenum, 826 lineinfo.hosts); 827 goto bad; 828 } 829 if (s == 1) { 830 lineinfo.status = HKF_STATUS_MATCHED; 831 lineinfo.match |= HKF_MATCH_IP | 832 (hashed ? HKF_MATCH_IP_HASHED : 0); 833 } 834 } 835 /* 836 * Skip this line if host matching requested and 837 * neither host nor address matched. 838 */ 839 if ((options & HKF_WANT_MATCH) != 0 && 840 lineinfo.status != HKF_STATUS_MATCHED) 841 continue; 842 } 843 844 /* Got a match. Skip host name and any following whitespace */ 845 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 846 ; 847 if (*cp2 == '\0' || *cp2 == '#') { 848 debug2("%s:%ld: truncated before key type", 849 path, linenum); 850 goto bad; 851 } 852 lineinfo.rawkey = cp = cp2; 853 854 if ((options & HKF_WANT_PARSE_KEY) != 0) { 855 /* 856 * Extract the key from the line. This will skip 857 * any leading whitespace. Ignore badly formatted 858 * lines. 859 */ 860 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) { 861 error_f("sshkey_new failed"); 862 r = SSH_ERR_ALLOC_FAIL; 863 break; 864 } 865 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) { 866 goto bad; 867 } 868 lineinfo.keytype = lineinfo.key->type; 869 lineinfo.comment = cp; 870 } else { 871 /* Extract and parse key type */ 872 l = strcspn(lineinfo.rawkey, " \t"); 873 if (l <= 1 || l >= sizeof(ktype) || 874 lineinfo.rawkey[l] == '\0') 875 goto bad; 876 memcpy(ktype, lineinfo.rawkey, l); 877 ktype[l] = '\0'; 878 lineinfo.keytype = sshkey_type_from_name(ktype); 879 880 /* 881 * Assume legacy RSA1 if the first component is a short 882 * decimal number. 883 */ 884 if (lineinfo.keytype == KEY_UNSPEC && l < 8 && 885 strspn(ktype, "0123456789") == l) 886 goto bad; 887 888 /* 889 * Check that something other than whitespace follows 890 * the key type. This won't catch all corruption, but 891 * it does catch trivial truncation. 892 */ 893 cp2 += l; /* Skip past key type */ 894 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 895 ; 896 if (*cp2 == '\0' || *cp2 == '#') { 897 debug2("%s:%ld: truncated after key type", 898 path, linenum); 899 lineinfo.keytype = KEY_UNSPEC; 900 } 901 if (lineinfo.keytype == KEY_UNSPEC) { 902 bad: 903 sshkey_free(lineinfo.key); 904 lineinfo.key = NULL; 905 lineinfo.status = HKF_STATUS_INVALID; 906 if ((r = callback(&lineinfo, ctx)) != 0) 907 break; 908 continue; 909 } 910 } 911 if ((r = callback(&lineinfo, ctx)) != 0) 912 break; 913 } 914 sshkey_free(lineinfo.key); 915 free(lineinfo.line); 916 free(line); 917 return r; 918 } 919 920 int 921 hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx, 922 const char *host, const char *ip, u_int options, u_int note) 923 { 924 FILE *f; 925 int r, oerrno; 926 927 if ((f = fopen(path, "r")) == NULL) 928 return SSH_ERR_SYSTEM_ERROR; 929 930 debug3_f("reading file \"%s\"", path); 931 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip, 932 options, note); 933 oerrno = errno; 934 fclose(f); 935 errno = oerrno; 936 return r; 937 } 938