hostfile.c revision 1.1.1.22
1 /* $OpenBSD: hostfile.c,v 1.100 2025/11/25 00:57:04 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) 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 <stdarg.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.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 char *encoded = NULL; 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 xasprintf(&encoded, "%s%s%c%s", HASH_MAGIC, uu_salt, HASH_DELIM, 145 uu_result); 146 147 return (encoded); 148 } 149 150 /* 151 * Parses an RSA key from a string. Moves the pointer over the key. 152 * Skips any whitespace at the beginning and at end. 153 */ 154 155 int 156 hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret) 157 { 158 char *cp; 159 160 /* Skip leading whitespace. */ 161 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) 162 ; 163 164 if (sshkey_read(ret, &cp) != 0) 165 return 0; 166 167 /* Skip trailing whitespace. */ 168 for (; *cp == ' ' || *cp == '\t'; cp++) 169 ; 170 171 /* Return results. */ 172 *cpp = cp; 173 if (bitsp != NULL) 174 *bitsp = sshkey_size(ret); 175 return 1; 176 } 177 178 static HostkeyMarker 179 check_markers(char **cpp) 180 { 181 char marker[32], *sp, *cp = *cpp; 182 int ret = MRK_NONE; 183 184 while (*cp == '@') { 185 /* Only one marker is allowed */ 186 if (ret != MRK_NONE) 187 return MRK_ERROR; 188 /* Markers are terminated by whitespace */ 189 if ((sp = strchr(cp, ' ')) == NULL && 190 (sp = strchr(cp, '\t')) == NULL) 191 return MRK_ERROR; 192 /* Extract marker for comparison */ 193 if (sp <= cp + 1 || sp >= cp + sizeof(marker)) 194 return MRK_ERROR; 195 memcpy(marker, cp, sp - cp); 196 marker[sp - cp] = '\0'; 197 if (strcmp(marker, CA_MARKER) == 0) 198 ret = MRK_CA; 199 else if (strcmp(marker, REVOKE_MARKER) == 0) 200 ret = MRK_REVOKE; 201 else 202 return MRK_ERROR; 203 204 /* Skip past marker and any whitespace that follows it */ 205 cp = sp; 206 for (; *cp == ' ' || *cp == '\t'; cp++) 207 ; 208 } 209 *cpp = cp; 210 return ret; 211 } 212 213 struct hostkeys * 214 init_hostkeys(void) 215 { 216 struct hostkeys *ret = xcalloc(1, sizeof(*ret)); 217 218 ret->entries = NULL; 219 return ret; 220 } 221 222 struct load_callback_ctx { 223 const char *host; 224 u_long num_loaded; 225 struct hostkeys *hostkeys; 226 }; 227 228 static int 229 record_hostkey(struct hostkey_foreach_line *l, void *_ctx) 230 { 231 struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx; 232 struct hostkeys *hostkeys = ctx->hostkeys; 233 struct hostkey_entry *tmp; 234 235 if (l->status == HKF_STATUS_INVALID) { 236 /* XXX make this verbose() in the future */ 237 debug("%s:%ld: parse error in hostkeys file", 238 l->path, l->linenum); 239 return 0; 240 } 241 242 debug3_f("found %skey type %s in file %s:%lu", 243 l->marker == MRK_NONE ? "" : 244 (l->marker == MRK_CA ? "ca " : "revoked "), 245 sshkey_type(l->key), l->path, l->linenum); 246 if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries, 247 hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL) 248 return SSH_ERR_ALLOC_FAIL; 249 hostkeys->entries = tmp; 250 hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host); 251 hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path); 252 hostkeys->entries[hostkeys->num_entries].line = l->linenum; 253 hostkeys->entries[hostkeys->num_entries].key = l->key; 254 l->key = NULL; /* steal it */ 255 hostkeys->entries[hostkeys->num_entries].marker = l->marker; 256 hostkeys->entries[hostkeys->num_entries].note = l->note; 257 hostkeys->num_entries++; 258 ctx->num_loaded++; 259 260 return 0; 261 } 262 263 void 264 load_hostkeys_file(struct hostkeys *hostkeys, const char *host, 265 const char *path, FILE *f, u_int note) 266 { 267 int r; 268 struct load_callback_ctx ctx; 269 270 ctx.host = host; 271 ctx.num_loaded = 0; 272 ctx.hostkeys = hostkeys; 273 274 if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host, 275 NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) { 276 if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT) 277 debug_fr(r, "hostkeys_foreach failed for %s", path); 278 } 279 if (ctx.num_loaded != 0) 280 debug3_f("loaded %lu keys from %s", ctx.num_loaded, host); 281 } 282 283 void 284 load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path, 285 u_int note) 286 { 287 FILE *f; 288 289 if ((f = fopen(path, "r")) == NULL) { 290 debug_f("fopen %s: %s", path, strerror(errno)); 291 return; 292 } 293 294 load_hostkeys_file(hostkeys, host, path, f, note); 295 fclose(f); 296 } 297 298 void 299 free_hostkeys(struct hostkeys *hostkeys) 300 { 301 u_int i; 302 303 for (i = 0; i < hostkeys->num_entries; i++) { 304 free(hostkeys->entries[i].host); 305 free(hostkeys->entries[i].file); 306 sshkey_free(hostkeys->entries[i].key); 307 explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); 308 } 309 free(hostkeys->entries); 310 freezero(hostkeys, sizeof(*hostkeys)); 311 } 312 313 static int 314 check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k) 315 { 316 int is_cert = sshkey_is_cert(k); 317 u_int i; 318 319 for (i = 0; i < hostkeys->num_entries; i++) { 320 if (hostkeys->entries[i].marker != MRK_REVOKE) 321 continue; 322 if (sshkey_equal_public(k, hostkeys->entries[i].key)) 323 return -1; 324 if (is_cert && k != NULL && 325 sshkey_equal_public(k->cert->signature_key, 326 hostkeys->entries[i].key)) 327 return -1; 328 } 329 return 0; 330 } 331 332 /* 333 * Match keys against a specified key, or look one up by key type. 334 * 335 * If looking for a keytype (key == NULL) and one is found then return 336 * HOST_FOUND, otherwise HOST_NEW. 337 * 338 * If looking for a key (key != NULL): 339 * 1. If the key is a cert and a matching CA is found, return HOST_OK 340 * 2. If the key is not a cert and a matching key is found, return HOST_OK 341 * 3. If no key matches but a key with a different type is found, then 342 * return HOST_CHANGED 343 * 4. If no matching keys are found, then return HOST_NEW. 344 * 345 * Finally, check any found key is not revoked. 346 */ 347 static HostStatus 348 check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, 349 struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found) 350 { 351 u_int i; 352 HostStatus end_return = HOST_NEW; 353 int want_cert = sshkey_is_cert(k); 354 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; 355 356 if (found != NULL) 357 *found = NULL; 358 359 for (i = 0; i < hostkeys->num_entries; i++) { 360 if (hostkeys->entries[i].marker != want_marker) 361 continue; 362 if (k == NULL) { 363 if (hostkeys->entries[i].key->type != keytype) 364 continue; 365 if (nid != -1 && 366 sshkey_type_plain(keytype) == KEY_ECDSA && 367 hostkeys->entries[i].key->ecdsa_nid != nid) 368 continue; 369 end_return = HOST_FOUND; 370 if (found != NULL) 371 *found = hostkeys->entries + i; 372 k = hostkeys->entries[i].key; 373 break; 374 } 375 if (want_cert) { 376 if (sshkey_equal_public(k->cert->signature_key, 377 hostkeys->entries[i].key)) { 378 /* A matching CA exists */ 379 end_return = HOST_OK; 380 if (found != NULL) 381 *found = hostkeys->entries + i; 382 break; 383 } 384 } else { 385 if (sshkey_equal(k, hostkeys->entries[i].key)) { 386 end_return = HOST_OK; 387 if (found != NULL) 388 *found = hostkeys->entries + i; 389 break; 390 } 391 /* A non-matching key exists */ 392 end_return = HOST_CHANGED; 393 if (found != NULL) 394 *found = hostkeys->entries + i; 395 } 396 } 397 if (check_key_not_revoked(hostkeys, k) != 0) { 398 end_return = HOST_REVOKED; 399 if (found != NULL) 400 *found = NULL; 401 } 402 return end_return; 403 } 404 405 HostStatus 406 check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key, 407 const struct hostkey_entry **found) 408 { 409 if (key == NULL) 410 fatal("no key to look up"); 411 return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found); 412 } 413 414 int 415 lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid, 416 const struct hostkey_entry **found) 417 { 418 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid, 419 found) == HOST_FOUND); 420 } 421 422 int 423 lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker) 424 { 425 u_int i; 426 427 for (i = 0; i < hostkeys->num_entries; i++) { 428 if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker) 429 return 1; 430 } 431 return 0; 432 } 433 434 static int 435 format_host_entry(struct sshbuf *entry, const char *host, const char *ip, 436 const struct sshkey *key, int store_hash) 437 { 438 int r, success = 0; 439 char *hashed_host = NULL, *lhost; 440 441 lhost = xstrdup(host); 442 lowercase(lhost); 443 444 if (store_hash) { 445 if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) { 446 error_f("host_hash failed"); 447 free(lhost); 448 return 0; 449 } 450 if ((r = sshbuf_putf(entry, "%s ", hashed_host)) != 0) 451 fatal_fr(r, "sshbuf_putf"); 452 } else if (ip != NULL) { 453 if ((r = sshbuf_putf(entry, "%s,%s ", lhost, ip)) != 0) 454 fatal_fr(r, "sshbuf_putf"); 455 } else { 456 if ((r = sshbuf_putf(entry, "%s ", lhost)) != 0) 457 fatal_fr(r, "sshbuf_putf"); 458 } 459 free(hashed_host); 460 free(lhost); 461 if ((r = sshkey_format_text(key, entry)) == 0) 462 success = 1; 463 else 464 error_fr(r, "sshkey_write"); 465 if ((r = sshbuf_putf(entry, "\n")) != 0) 466 fatal_fr(r, "sshbuf_putf"); 467 468 /* If hashing is enabled, the IP address needs to go on its own line */ 469 if (success && store_hash && ip != NULL) 470 success = format_host_entry(entry, ip, NULL, key, 1); 471 return success; 472 } 473 474 static int 475 write_host_entry(FILE *f, const char *host, const char *ip, 476 const struct sshkey *key, int store_hash) 477 { 478 int r, success = 0; 479 struct sshbuf *entry = NULL; 480 481 if ((entry = sshbuf_new()) == NULL) 482 fatal_f("allocation failed"); 483 if ((r = format_host_entry(entry, host, ip, key, store_hash)) != 1) { 484 debug_f("failed to format host entry"); 485 goto out; 486 } 487 if ((r = fwrite(sshbuf_ptr(entry), sshbuf_len(entry), 1, f)) != 1) { 488 error_f("fwrite: %s", strerror(errno)); 489 goto out; 490 } 491 success = 1; 492 out: 493 sshbuf_free(entry); 494 return success; 495 } 496 497 /* 498 * Create user ~/.ssh directory if it doesn't exist and we want to write to it. 499 * If notify is set, a message will be emitted if the directory is created. 500 */ 501 void 502 hostfile_create_user_ssh_dir(const char *filename, int notify) 503 { 504 char *dotsshdir = NULL, *p; 505 size_t len; 506 struct stat st; 507 508 if ((p = strrchr(filename, '/')) == NULL) 509 return; 510 len = p - filename; 511 dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid()); 512 if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0) 513 goto out; /* not ~/.ssh prefixed */ 514 if (stat(dotsshdir, &st) == 0) 515 goto out; /* dir already exists */ 516 else if (errno != ENOENT) 517 error("Could not stat %s: %s", dotsshdir, strerror(errno)); 518 else { 519 if (mkdir(dotsshdir, 0700) == -1) 520 error("Could not create directory '%.200s' (%s).", 521 dotsshdir, strerror(errno)); 522 else if (notify) 523 logit("Created directory '%s'.", dotsshdir); 524 } 525 out: 526 free(dotsshdir); 527 } 528 529 530 /* 531 * Appends an entry to the host file. Returns false if the entry could not 532 * be appended. 533 */ 534 int 535 add_host_to_hostfile(const char *filename, const char *host, 536 const struct sshkey *key, int store_hash) 537 { 538 FILE *f; 539 int success, addnl = 0; 540 541 if (key == NULL) 542 return 1; /* XXX ? */ 543 hostfile_create_user_ssh_dir(filename, 0); 544 if ((f = fopen(filename, "a+")) == NULL) 545 return 0; 546 setvbuf(f, NULL, _IONBF, 0); 547 /* Make sure we have a terminating newline. */ 548 if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n') 549 addnl = 1; 550 if (fseek(f, 0L, SEEK_END) != 0 || (addnl && fputc('\n', f) != '\n')) { 551 error("Failed to add terminating newline to %s: %s", 552 filename, strerror(errno)); 553 fclose(f); 554 return 0; 555 } 556 success = write_host_entry(f, host, NULL, key, store_hash); 557 fclose(f); 558 return success; 559 } 560 561 struct host_delete_ctx { 562 FILE *out; 563 int quiet; 564 const char *host, *ip; 565 u_int *match_keys; /* mask of HKF_MATCH_* for this key */ 566 struct sshkey * const *keys; 567 size_t nkeys; 568 int modified; 569 }; 570 571 static int 572 host_delete(struct hostkey_foreach_line *l, void *_ctx) 573 { 574 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx; 575 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 576 size_t i; 577 578 /* Don't remove CA and revocation lines */ 579 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) { 580 /* 581 * If this line contains one of the keys that we will be 582 * adding later, then don't change it and mark the key for 583 * skipping. 584 */ 585 for (i = 0; i < ctx->nkeys; i++) { 586 if (!sshkey_equal(ctx->keys[i], l->key)) 587 continue; 588 ctx->match_keys[i] |= l->match; 589 fprintf(ctx->out, "%s\n", l->line); 590 debug3_f("%s key already at %s:%ld", 591 sshkey_type(l->key), l->path, l->linenum); 592 return 0; 593 } 594 595 /* 596 * Hostname matches and has no CA/revoke marker, delete it 597 * by *not* writing the line to ctx->out. 598 */ 599 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s", 600 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 601 l->path, l->linenum, sshkey_type(l->key), ctx->host); 602 ctx->modified = 1; 603 return 0; 604 } 605 /* Retain non-matching hosts and invalid lines when deleting */ 606 if (l->status == HKF_STATUS_INVALID) { 607 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry", 608 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 609 l->path, l->linenum); 610 } 611 fprintf(ctx->out, "%s\n", l->line); 612 return 0; 613 } 614 615 int 616 hostfile_replace_entries(const char *filename, const char *host, const char *ip, 617 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg) 618 { 619 int r, fd, oerrno = 0; 620 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 621 struct host_delete_ctx ctx; 622 char *fp = NULL, *temp = NULL, *back = NULL; 623 const char *what; 624 mode_t omask; 625 size_t i; 626 u_int want; 627 628 omask = umask(077); 629 630 memset(&ctx, 0, sizeof(ctx)); 631 ctx.host = host; 632 ctx.ip = ip; 633 ctx.quiet = quiet; 634 635 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL) 636 return SSH_ERR_ALLOC_FAIL; 637 ctx.keys = keys; 638 ctx.nkeys = nkeys; 639 ctx.modified = 0; 640 641 /* 642 * Prepare temporary file for in-place deletion. 643 */ 644 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 || 645 (r = asprintf(&back, "%s.old", filename)) == -1) { 646 r = SSH_ERR_ALLOC_FAIL; 647 goto fail; 648 } 649 650 if ((fd = mkstemp(temp)) == -1) { 651 oerrno = errno; 652 error_f("mkstemp: %s", strerror(oerrno)); 653 r = SSH_ERR_SYSTEM_ERROR; 654 goto fail; 655 } 656 if ((ctx.out = fdopen(fd, "w")) == NULL) { 657 oerrno = errno; 658 close(fd); 659 error_f("fdopen: %s", strerror(oerrno)); 660 r = SSH_ERR_SYSTEM_ERROR; 661 goto fail; 662 } 663 664 /* Remove stale/mismatching entries for the specified host */ 665 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip, 666 HKF_WANT_PARSE_KEY, 0)) != 0) { 667 oerrno = errno; 668 error_fr(r, "hostkeys_foreach"); 669 goto fail; 670 } 671 672 /* Re-add the requested keys */ 673 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP); 674 for (i = 0; i < nkeys; i++) { 675 if (keys[i] == NULL || (want & ctx.match_keys[i]) == want) 676 continue; 677 if ((fp = sshkey_fingerprint(keys[i], hash_alg, 678 SSH_FP_DEFAULT)) == NULL) { 679 r = SSH_ERR_ALLOC_FAIL; 680 goto fail; 681 } 682 /* write host/ip */ 683 what = ""; 684 if (ctx.match_keys[i] == 0) { 685 what = "Adding new key"; 686 if (!write_host_entry(ctx.out, host, ip, 687 keys[i], store_hash)) { 688 r = SSH_ERR_INTERNAL_ERROR; 689 goto fail; 690 } 691 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) { 692 what = "Fixing match (hostname)"; 693 if (!write_host_entry(ctx.out, host, NULL, 694 keys[i], store_hash)) { 695 r = SSH_ERR_INTERNAL_ERROR; 696 goto fail; 697 } 698 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) { 699 what = "Fixing match (address)"; 700 if (!write_host_entry(ctx.out, ip, NULL, 701 keys[i], store_hash)) { 702 r = SSH_ERR_INTERNAL_ERROR; 703 goto fail; 704 } 705 } 706 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s", 707 quiet ? __func__ : "", quiet ? ": " : "", what, 708 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename, 709 sshkey_ssh_name(keys[i]), fp); 710 free(fp); 711 fp = NULL; 712 ctx.modified = 1; 713 } 714 fclose(ctx.out); 715 ctx.out = NULL; 716 717 if (ctx.modified) { 718 /* Backup the original file and replace it with the temporary */ 719 if (unlink(back) == -1 && errno != ENOENT) { 720 oerrno = errno; 721 error_f("unlink %.100s: %s", back, strerror(errno)); 722 r = SSH_ERR_SYSTEM_ERROR; 723 goto fail; 724 } 725 if (link(filename, back) == -1) { 726 oerrno = errno; 727 error_f("link %.100s to %.100s: %s", filename, 728 back, strerror(errno)); 729 r = SSH_ERR_SYSTEM_ERROR; 730 goto fail; 731 } 732 if (rename(temp, filename) == -1) { 733 oerrno = errno; 734 error_f("rename \"%s\" to \"%s\": %s", temp, 735 filename, strerror(errno)); 736 r = SSH_ERR_SYSTEM_ERROR; 737 goto fail; 738 } 739 } else { 740 /* No changes made; just delete the temporary file */ 741 if (unlink(temp) != 0) 742 error_f("unlink \"%s\": %s", temp, strerror(errno)); 743 } 744 745 /* success */ 746 r = 0; 747 fail: 748 if (temp != NULL && r != 0) 749 unlink(temp); 750 free(temp); 751 free(back); 752 free(fp); 753 if (ctx.out != NULL) 754 fclose(ctx.out); 755 free(ctx.match_keys); 756 umask(omask); 757 if (r == SSH_ERR_SYSTEM_ERROR) 758 errno = oerrno; 759 return r; 760 } 761 762 static int 763 match_maybe_hashed(const char *host, const char *names, int *was_hashed) 764 { 765 int hashed = *names == HASH_DELIM, ret; 766 char *hashed_host = NULL; 767 size_t nlen = strlen(names); 768 769 if (was_hashed != NULL) 770 *was_hashed = hashed; 771 if (hashed) { 772 if ((hashed_host = host_hash(host, names, nlen)) == NULL) 773 return -1; 774 ret = (nlen == strlen(hashed_host) && 775 strncmp(hashed_host, names, nlen) == 0); 776 free(hashed_host); 777 return ret; 778 } 779 return match_hostname(host, names) == 1; 780 } 781 782 int 783 hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback, 784 void *ctx, const char *host, const char *ip, u_int options, u_int note) 785 { 786 char *line = NULL, ktype[128]; 787 u_long linenum = 0; 788 char *cp, *cp2; 789 u_int kbits; 790 int hashed; 791 int s, r = 0; 792 struct hostkey_foreach_line lineinfo; 793 size_t linesize = 0, l; 794 795 memset(&lineinfo, 0, sizeof(lineinfo)); 796 if (host == NULL && (options & HKF_WANT_MATCH) != 0) 797 return SSH_ERR_INVALID_ARGUMENT; 798 799 while (getline(&line, &linesize, f) != -1) { 800 linenum++; 801 line[strcspn(line, "\n")] = '\0'; 802 803 free(lineinfo.line); 804 sshkey_free(lineinfo.key); 805 memset(&lineinfo, 0, sizeof(lineinfo)); 806 lineinfo.path = path; 807 lineinfo.linenum = linenum; 808 lineinfo.line = xstrdup(line); 809 lineinfo.marker = MRK_NONE; 810 lineinfo.status = HKF_STATUS_OK; 811 lineinfo.keytype = KEY_UNSPEC; 812 lineinfo.note = note; 813 814 /* Skip any leading whitespace, comments and empty lines. */ 815 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 816 ; 817 if (!*cp || *cp == '#' || *cp == '\n') { 818 if ((options & HKF_WANT_MATCH) == 0) { 819 lineinfo.status = HKF_STATUS_COMMENT; 820 if ((r = callback(&lineinfo, ctx)) != 0) 821 break; 822 } 823 continue; 824 } 825 826 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) { 827 verbose_f("invalid marker at %s:%lu", path, linenum); 828 if ((options & HKF_WANT_MATCH) == 0) 829 goto bad; 830 continue; 831 } 832 833 /* Find the end of the host name portion. */ 834 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) 835 ; 836 if (*cp2 == '\0') { 837 verbose_f("truncated line at %s:%lu", path, linenum); 838 if ((options & HKF_WANT_MATCH) == 0) 839 goto bad; 840 continue; 841 } 842 lineinfo.hosts = cp; 843 *cp2++ = '\0'; 844 845 /* Check if the host name matches. */ 846 if (host != NULL) { 847 if ((s = match_maybe_hashed(host, lineinfo.hosts, 848 &hashed)) == -1) { 849 debug2_f("%s:%ld: bad host hash \"%.32s\"", 850 path, linenum, lineinfo.hosts); 851 goto bad; 852 } 853 if (s == 1) { 854 lineinfo.status = HKF_STATUS_MATCHED; 855 lineinfo.match |= HKF_MATCH_HOST | 856 (hashed ? HKF_MATCH_HOST_HASHED : 0); 857 } 858 /* Try matching IP address if supplied */ 859 if (ip != NULL) { 860 if ((s = match_maybe_hashed(ip, lineinfo.hosts, 861 &hashed)) == -1) { 862 debug2_f("%s:%ld: bad ip hash " 863 "\"%.32s\"", path, linenum, 864 lineinfo.hosts); 865 goto bad; 866 } 867 if (s == 1) { 868 lineinfo.status = HKF_STATUS_MATCHED; 869 lineinfo.match |= HKF_MATCH_IP | 870 (hashed ? HKF_MATCH_IP_HASHED : 0); 871 } 872 } 873 /* 874 * Skip this line if host matching requested and 875 * neither host nor address matched. 876 */ 877 if ((options & HKF_WANT_MATCH) != 0 && 878 lineinfo.status != HKF_STATUS_MATCHED) 879 continue; 880 } 881 882 /* Got a match. Skip host name and any following whitespace */ 883 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 884 ; 885 if (*cp2 == '\0' || *cp2 == '#') { 886 debug2("%s:%ld: truncated before key type", 887 path, linenum); 888 goto bad; 889 } 890 lineinfo.rawkey = cp = cp2; 891 892 if ((options & HKF_WANT_PARSE_KEY) != 0) { 893 /* 894 * Extract the key from the line. This will skip 895 * any leading whitespace. Ignore badly formatted 896 * lines. 897 */ 898 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) { 899 error_f("sshkey_new failed"); 900 r = SSH_ERR_ALLOC_FAIL; 901 break; 902 } 903 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) { 904 goto bad; 905 } 906 lineinfo.keytype = lineinfo.key->type; 907 lineinfo.comment = cp; 908 } else { 909 /* Extract and parse key type */ 910 l = strcspn(lineinfo.rawkey, " \t"); 911 if (l <= 1 || l >= sizeof(ktype) || 912 lineinfo.rawkey[l] == '\0') 913 goto bad; 914 memcpy(ktype, lineinfo.rawkey, l); 915 ktype[l] = '\0'; 916 lineinfo.keytype = sshkey_type_from_name(ktype); 917 918 /* 919 * Assume legacy RSA1 if the first component is a short 920 * decimal number. 921 */ 922 if (lineinfo.keytype == KEY_UNSPEC && l < 8 && 923 strspn(ktype, "0123456789") == l) 924 goto bad; 925 926 /* 927 * Check that something other than whitespace follows 928 * the key type. This won't catch all corruption, but 929 * it does catch trivial truncation. 930 */ 931 cp2 += l; /* Skip past key type */ 932 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 933 ; 934 if (*cp2 == '\0' || *cp2 == '#') { 935 debug2("%s:%ld: truncated after key type", 936 path, linenum); 937 lineinfo.keytype = KEY_UNSPEC; 938 } 939 if (lineinfo.keytype == KEY_UNSPEC) { 940 bad: 941 sshkey_free(lineinfo.key); 942 lineinfo.key = NULL; 943 lineinfo.status = HKF_STATUS_INVALID; 944 if ((r = callback(&lineinfo, ctx)) != 0) 945 break; 946 continue; 947 } 948 } 949 if ((r = callback(&lineinfo, ctx)) != 0) 950 break; 951 } 952 sshkey_free(lineinfo.key); 953 free(lineinfo.line); 954 free(line); 955 return r; 956 } 957 958 int 959 hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx, 960 const char *host, const char *ip, u_int options, u_int note) 961 { 962 FILE *f; 963 int r, oerrno; 964 965 if ((f = fopen(path, "r")) == NULL) 966 return SSH_ERR_SYSTEM_ERROR; 967 968 debug3_f("reading file \"%s\"", path); 969 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip, 970 options, note); 971 oerrno = errno; 972 fclose(f); 973 errno = oerrno; 974 return r; 975 } 976
Indexes created Sat Apr 25 00:22:52 UTC 2026