1/* $NetBSD: hostfile.c,v 1.23 2023/07/26 17:58:15 christos Exp $ */ 2/* $OpenBSD: hostfile.c,v 1.95 2023/02/21 06:48:18 dtucker Exp $ */ 3/* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * Functions for manipulating the known hosts files. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * 16 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. 17 * Copyright (c) 1999 Niels Provos. All rights reserved. 18 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 1. Redistributions of source code must retain the above copyright 23 * notice, this list of conditions and the following disclaimer. 24 * 2. Redistributions in binary form must reproduce the above copyright 25 * notice, this list of conditions and the following disclaimer in the 26 * documentation and/or other materials provided with the distribution. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40#include "includes.h" 41__RCSID("$NetBSD: hostfile.c,v 1.23 2023/07/26 17:58:15 christos Exp $"); 42#include <sys/types.h> 43#include <sys/stat.h> 44 45#include <netinet/in.h> 46 47#include <errno.h> 48#include <resolv.h> 49#include <stdarg.h> 50#include <stdio.h> 51#include <stdlib.h> 52#include <string.h> 53#include <unistd.h> 54 55#include "xmalloc.h" 56#include "match.h" 57#include "sshkey.h" 58#include "hostfile.h" 59#include "log.h" 60#include "misc.h" 61#include "pathnames.h" 62#include "ssherr.h" 63#include "digest.h" 64#include "hmac.h" 65#include "sshbuf.h" 66 67/* XXX hmac is too easy to dictionary attack; use bcrypt? */ 68 69static int 70extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len) 71{ 72 char *p, *b64salt; 73 u_int b64len; 74 int ret; 75 76 if (l < sizeof(HASH_MAGIC) - 1) { 77 debug2("extract_salt: string too short"); 78 return (-1); 79 } 80 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { 81 debug2("extract_salt: invalid magic identifier"); 82 return (-1); 83 } 84 s += sizeof(HASH_MAGIC) - 1; 85 l -= sizeof(HASH_MAGIC) - 1; 86 if ((p = memchr(s, HASH_DELIM, l)) == NULL) { 87 debug2("extract_salt: missing salt termination character"); 88 return (-1); 89 } 90 91 b64len = p - s; 92 /* Sanity check */ 93 if (b64len == 0 || b64len > 1024) { 94 debug2("extract_salt: bad encoded salt length %u", b64len); 95 return (-1); 96 } 97 b64salt = xmalloc(1 + b64len); 98 memcpy(b64salt, s, b64len); 99 b64salt[b64len] = '\0'; 100 101 ret = __b64_pton(b64salt, salt, salt_len); 102 free(b64salt); 103 if (ret == -1) { 104 debug2("extract_salt: salt decode error"); 105 return (-1); 106 } 107 if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) { 108 debug2("extract_salt: expected salt len %zd, got %d", 109 ssh_hmac_bytes(SSH_DIGEST_SHA1), ret); 110 return (-1); 111 } 112 113 return (0); 114} 115 116char * 117host_hash(const char *host, const char *name_from_hostfile, u_int src_len) 118{ 119 struct ssh_hmac_ctx *ctx; 120 u_char salt[256], result[256]; 121 char uu_salt[512], uu_result[512]; 122 char *encoded = NULL; 123 u_int len; 124 125 len = ssh_digest_bytes(SSH_DIGEST_SHA1); 126 127 if (name_from_hostfile == NULL) { 128 /* Create new salt */ 129 arc4random_buf(salt, len); 130 } else { 131 /* Extract salt from known host entry */ 132 if (extract_salt(name_from_hostfile, src_len, salt, 133 sizeof(salt)) == -1) 134 return (NULL); 135 } 136 137 if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || 138 ssh_hmac_init(ctx, salt, len) < 0 || 139 ssh_hmac_update(ctx, host, strlen(host)) < 0 || 140 ssh_hmac_final(ctx, result, sizeof(result))) 141 fatal_f("ssh_hmac failed"); 142 ssh_hmac_free(ctx); 143 144 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || 145 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) 146 fatal_f("__b64_ntop failed"); 147 xasprintf(&encoded, "%s%s%c%s", HASH_MAGIC, uu_salt, HASH_DELIM, 148 uu_result); 149 150 return (encoded); 151} 152 153/* 154 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the 155 * pointer over the key. Skips any whitespace at the beginning and at end. 156 */ 157 158int 159hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret) 160{ 161 char *cp; 162 163 /* Skip leading whitespace. */ 164 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) 165 ; 166 167 if (sshkey_read(ret, &cp) != 0) 168 return 0; 169 170 /* Skip trailing whitespace. */ 171 for (; *cp == ' ' || *cp == '\t'; cp++) 172 ; 173 174 /* Return results. */ 175 *cpp = cp; 176 if (bitsp != NULL) 177 *bitsp = sshkey_size(ret); 178 return 1; 179} 180 181static HostkeyMarker 182check_markers(char **cpp) 183{ 184 char marker[32], *sp, *cp = *cpp; 185 int ret = MRK_NONE; 186 187 while (*cp == '@') { 188 /* Only one marker is allowed */ 189 if (ret != MRK_NONE) 190 return MRK_ERROR; 191 /* Markers are terminated by whitespace */ 192 if ((sp = strchr(cp, ' ')) == NULL && 193 (sp = strchr(cp, '\t')) == NULL) 194 return MRK_ERROR; 195 /* Extract marker for comparison */ 196 if (sp <= cp + 1 || sp >= cp + sizeof(marker)) 197 return MRK_ERROR; 198 memcpy(marker, cp, sp - cp); 199 marker[sp - cp] = '\0'; 200 if (strcmp(marker, CA_MARKER) == 0) 201 ret = MRK_CA; 202 else if (strcmp(marker, REVOKE_MARKER) == 0) 203 ret = MRK_REVOKE; 204 else 205 return MRK_ERROR; 206 207 /* Skip past marker and any whitespace that follows it */ 208 cp = sp; 209 for (; *cp == ' ' || *cp == '\t'; cp++) 210 ; 211 } 212 *cpp = cp; 213 return ret; 214} 215 216struct hostkeys * 217init_hostkeys(void) 218{ 219 struct hostkeys *ret = xcalloc(1, sizeof(*ret)); 220 221 ret->entries = NULL; 222 return ret; 223} 224 225struct load_callback_ctx { 226 const char *host; 227 u_long num_loaded; 228 struct hostkeys *hostkeys; 229}; 230 231static int 232record_hostkey(struct hostkey_foreach_line *l, void *_ctx) 233{ 234 struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx; 235 struct hostkeys *hostkeys = ctx->hostkeys; 236 struct hostkey_entry *tmp; 237 238 if (l->status == HKF_STATUS_INVALID) { 239 /* XXX make this verbose() in the future */ 240 debug("%s:%ld: parse error in hostkeys file", 241 l->path, l->linenum); 242 return 0; 243 } 244 245 debug3_f("found %skey type %s in file %s:%lu", 246 l->marker == MRK_NONE ? "" : 247 (l->marker == MRK_CA ? "ca " : "revoked "), 248 sshkey_type(l->key), l->path, l->linenum); 249 if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries, 250 hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL) 251 return SSH_ERR_ALLOC_FAIL; 252 hostkeys->entries = tmp; 253 hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host); 254 hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path); 255 hostkeys->entries[hostkeys->num_entries].line = l->linenum; 256 hostkeys->entries[hostkeys->num_entries].key = l->key; 257 l->key = NULL; /* steal it */ 258 hostkeys->entries[hostkeys->num_entries].marker = l->marker; 259 hostkeys->entries[hostkeys->num_entries].note = l->note; 260 hostkeys->num_entries++; 261 ctx->num_loaded++; 262 263 return 0; 264} 265 266void 267load_hostkeys_file(struct hostkeys *hostkeys, const char *host, 268 const char *path, FILE *f, u_int note) 269{ 270 int r; 271 struct load_callback_ctx ctx; 272 273 ctx.host = host; 274 ctx.num_loaded = 0; 275 ctx.hostkeys = hostkeys; 276 277 if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host, 278 NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) { 279 if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT) 280 debug_fr(r, "hostkeys_foreach failed for %s", path); 281 } 282 if (ctx.num_loaded != 0) 283 debug3_f("loaded %lu keys from %s", ctx.num_loaded, host); 284} 285 286void 287load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path, 288 u_int note) 289{ 290 FILE *f; 291 292 if ((f = fopen(path, "r")) == NULL) { 293 debug_f("fopen %s: %s", path, strerror(errno)); 294 return; 295 } 296 297 load_hostkeys_file(hostkeys, host, path, f, note); 298 fclose(f); 299} 300 301void 302free_hostkeys(struct hostkeys *hostkeys) 303{ 304 u_int i; 305 306 for (i = 0; i < hostkeys->num_entries; i++) { 307 free(hostkeys->entries[i].host); 308 free(hostkeys->entries[i].file); 309 sshkey_free(hostkeys->entries[i].key); 310 explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); 311 } 312 free(hostkeys->entries); 313 freezero(hostkeys, sizeof(*hostkeys)); 314} 315 316static int 317check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k) 318{ 319 int is_cert = sshkey_is_cert(k); 320 u_int i; 321 322 for (i = 0; i < hostkeys->num_entries; i++) { 323 if (hostkeys->entries[i].marker != MRK_REVOKE) 324 continue; 325 if (sshkey_equal_public(k, hostkeys->entries[i].key)) 326 return -1; 327 if (is_cert && k != NULL && 328 sshkey_equal_public(k->cert->signature_key, 329 hostkeys->entries[i].key)) 330 return -1; 331 } 332 return 0; 333} 334 335/* 336 * Match keys against a specified key, or look one up by key type. 337 * 338 * If looking for a keytype (key == NULL) and one is found then return 339 * HOST_FOUND, otherwise HOST_NEW. 340 * 341 * If looking for a key (key != NULL): 342 * 1. If the key is a cert and a matching CA is found, return HOST_OK 343 * 2. If the key is not a cert and a matching key is found, return HOST_OK 344 * 3. If no key matches but a key with a different type is found, then 345 * return HOST_CHANGED 346 * 4. If no matching keys are found, then return HOST_NEW. 347 * 348 * Finally, check any found key is not revoked. 349 */ 350static HostStatus 351check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, 352 struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found) 353{ 354 u_int i; 355 HostStatus end_return = HOST_NEW; 356 int want_cert = sshkey_is_cert(k); 357 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; 358 359 if (found != NULL) 360 *found = NULL; 361 362 for (i = 0; i < hostkeys->num_entries; i++) { 363 if (hostkeys->entries[i].marker != want_marker) 364 continue; 365 if (k == NULL) { 366 if (hostkeys->entries[i].key->type != keytype) 367 continue; 368 if (nid != -1 && 369 sshkey_type_plain(keytype) == KEY_ECDSA && 370 hostkeys->entries[i].key->ecdsa_nid != nid) 371 continue; 372 end_return = HOST_FOUND; 373 if (found != NULL) 374 *found = hostkeys->entries + i; 375 k = hostkeys->entries[i].key; 376 break; 377 } 378 if (want_cert) { 379 if (sshkey_equal_public(k->cert->signature_key, 380 hostkeys->entries[i].key)) { 381 /* A matching CA exists */ 382 end_return = HOST_OK; 383 if (found != NULL) 384 *found = hostkeys->entries + i; 385 break; 386 } 387 } else { 388 if (sshkey_equal(k, hostkeys->entries[i].key)) { 389 end_return = HOST_OK; 390 if (found != NULL) 391 *found = hostkeys->entries + i; 392 break; 393 } 394 /* A non-matching key exists */ 395 end_return = HOST_CHANGED; 396 if (found != NULL) 397 *found = hostkeys->entries + i; 398 } 399 } 400 if (check_key_not_revoked(hostkeys, k) != 0) { 401 end_return = HOST_REVOKED; 402 if (found != NULL) 403 *found = NULL; 404 } 405 return end_return; 406} 407 408HostStatus 409check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key, 410 const struct hostkey_entry **found) 411{ 412 if (key == NULL) 413 fatal("no key to look up"); 414 return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found); 415} 416 417int 418lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid, 419 const struct hostkey_entry **found) 420{ 421 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid, 422 found) == HOST_FOUND); 423} 424 425int 426lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker) 427{ 428 u_int i; 429 430 for (i = 0; i < hostkeys->num_entries; i++) { 431 if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker) 432 return 1; 433 } 434 return 0; 435} 436 437static int 438write_host_entry(FILE *f, const char *host, const char *ip, 439 const struct sshkey *key, int store_hash) 440{ 441 int r, success = 0; 442 char *hashed_host = NULL, *lhost; 443 444 lhost = xstrdup(host); 445 lowercase(lhost); 446 447 if (store_hash) { 448 if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) { 449 error_f("host_hash failed"); 450 free(lhost); 451 return 0; 452 } 453 fprintf(f, "%s ", hashed_host); 454 } else if (ip != NULL) 455 fprintf(f, "%s,%s ", lhost, ip); 456 else { 457 fprintf(f, "%s ", lhost); 458 } 459 free(hashed_host); 460 free(lhost); 461 if ((r = sshkey_write(key, f)) == 0) 462 success = 1; 463 else 464 error_fr(r, "sshkey_write"); 465 fputc('\n', f); 466 /* If hashing is enabled, the IP address needs to go on its own line */ 467 if (success && store_hash && ip != NULL) 468 success = write_host_entry(f, ip, NULL, key, 1); 469 return success; 470} 471 472/* 473 * Create user ~/.ssh directory if it doesn't exist and we want to write to it. 474 * If notify is set, a message will be emitted if the directory is created. 475 */ 476void 477hostfile_create_user_ssh_dir(const char *filename, int notify) 478{ 479 char *dotsshdir = NULL, *p; 480 size_t len; 481 struct stat st; 482 483 if ((p = strrchr(filename, '/')) == NULL) 484 return; 485 len = p - filename; 486 dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid()); 487 if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0) 488 goto out; /* not ~/.ssh prefixed */ 489 if (stat(dotsshdir, &st) == 0) 490 goto out; /* dir already exists */ 491 else if (errno != ENOENT) 492 error("Could not stat %s: %s", dotsshdir, strerror(errno)); 493 else { 494 if (mkdir(dotsshdir, 0700) == -1) 495 error("Could not create directory '%.200s' (%s).", 496 dotsshdir, strerror(errno)); 497 else if (notify) 498 logit("Created directory '%s'.", dotsshdir); 499 } 500 out: 501 free(dotsshdir); 502} 503 504 505/* 506 * Appends an entry to the host file. Returns false if the entry could not 507 * be appended. 508 */ 509int 510add_host_to_hostfile(const char *filename, const char *host, 511 const struct sshkey *key, int store_hash) 512{ 513 FILE *f; 514 int success, addnl = 0; 515 516 if (key == NULL) 517 return 1; /* XXX ? */ 518 hostfile_create_user_ssh_dir(filename, 0); 519 f = fopen(filename, "a+"); 520 if (!f) 521 return 0; 522 /* Make sure we have a terminating newline. */ 523 if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n') 524 addnl = 1; 525 if (fseek(f, 0L, SEEK_END) != 0 || (addnl && fputc('\n', f) != '\n')) { 526 error("Failed to add terminating newline to %s: %s", 527 filename, strerror(errno)); 528 fclose(f); 529 return 0; 530 } 531 success = write_host_entry(f, host, NULL, key, store_hash); 532 fclose(f); 533 return success; 534} 535 536struct host_delete_ctx { 537 FILE *out; 538 int quiet; 539 const char *host, *ip; 540 u_int *match_keys; /* mask of HKF_MATCH_* for this key */ 541 struct sshkey * const *keys; 542 size_t nkeys; 543 int modified; 544}; 545 546static int 547host_delete(struct hostkey_foreach_line *l, void *_ctx) 548{ 549 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx; 550 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 551 size_t i; 552 553 /* Don't remove CA and revocation lines */ 554 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) { 555 /* 556 * If this line contains one of the keys that we will be 557 * adding later, then don't change it and mark the key for 558 * skipping. 559 */ 560 for (i = 0; i < ctx->nkeys; i++) { 561 if (!sshkey_equal(ctx->keys[i], l->key)) 562 continue; 563 ctx->match_keys[i] |= l->match; 564 fprintf(ctx->out, "%s\n", l->line); 565 debug3_f("%s key already at %s:%ld", 566 sshkey_type(l->key), l->path, l->linenum); 567 return 0; 568 } 569 570 /* 571 * Hostname matches and has no CA/revoke marker, delete it 572 * by *not* writing the line to ctx->out. 573 */ 574 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s", 575 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 576 l->path, l->linenum, sshkey_type(l->key), ctx->host); 577 ctx->modified = 1; 578 return 0; 579 } 580 /* Retain non-matching hosts and invalid lines when deleting */ 581 if (l->status == HKF_STATUS_INVALID) { 582 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry", 583 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "", 584 l->path, l->linenum); 585 } 586 fprintf(ctx->out, "%s\n", l->line); 587 return 0; 588} 589 590int 591hostfile_replace_entries(const char *filename, const char *host, const char *ip, 592 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg) 593{ 594 int r, fd, oerrno = 0; 595 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE; 596 struct host_delete_ctx ctx; 597 char *fp, *temp = NULL, *back = NULL; 598 const char *what; 599 mode_t omask; 600 size_t i; 601 u_int want; 602 603 omask = umask(077); 604 605 memset(&ctx, 0, sizeof(ctx)); 606 ctx.host = host; 607 ctx.ip = ip; 608 ctx.quiet = quiet; 609 610 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL) 611 return SSH_ERR_ALLOC_FAIL; 612 ctx.keys = keys; 613 ctx.nkeys = nkeys; 614 ctx.modified = 0; 615 616 /* 617 * Prepare temporary file for in-place deletion. 618 */ 619 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 || 620 (r = asprintf(&back, "%s.old", filename)) == -1) { 621 r = SSH_ERR_ALLOC_FAIL; 622 goto fail; 623 } 624 625 if ((fd = mkstemp(temp)) == -1) { 626 oerrno = errno; 627 error_f("mkstemp: %s", strerror(oerrno)); 628 r = SSH_ERR_SYSTEM_ERROR; 629 goto fail; 630 } 631 if ((ctx.out = fdopen(fd, "w")) == NULL) { 632 oerrno = errno; 633 close(fd); 634 error_f("fdopen: %s", strerror(oerrno)); 635 r = SSH_ERR_SYSTEM_ERROR; 636 goto fail; 637 } 638 639 /* Remove stale/mismatching entries for the specified host */ 640 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip, 641 HKF_WANT_PARSE_KEY, 0)) != 0) { 642 oerrno = errno; 643 error_fr(r, "hostkeys_foreach"); 644 goto fail; 645 } 646 647 /* Re-add the requested keys */ 648 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP); 649 for (i = 0; i < nkeys; i++) { 650 if (keys[i] == NULL || (want & ctx.match_keys[i]) == want) 651 continue; 652 if ((fp = sshkey_fingerprint(keys[i], hash_alg, 653 SSH_FP_DEFAULT)) == NULL) { 654 r = SSH_ERR_ALLOC_FAIL; 655 goto fail; 656 } 657 /* write host/ip */ 658 what = ""; 659 if (ctx.match_keys[i] == 0) { 660 what = "Adding new key"; 661 if (!write_host_entry(ctx.out, host, ip, 662 keys[i], store_hash)) { 663 r = SSH_ERR_INTERNAL_ERROR; 664 goto fail; 665 } 666 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) { 667 what = "Fixing match (hostname)"; 668 if (!write_host_entry(ctx.out, host, NULL, 669 keys[i], store_hash)) { 670 r = SSH_ERR_INTERNAL_ERROR; 671 goto fail; 672 } 673 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) { 674 what = "Fixing match (address)"; 675 if (!write_host_entry(ctx.out, ip, NULL, 676 keys[i], store_hash)) { 677 r = SSH_ERR_INTERNAL_ERROR; 678 goto fail; 679 } 680 } 681 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s", 682 quiet ? __func__ : "", quiet ? ": " : "", what, 683 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename, 684 sshkey_ssh_name(keys[i]), fp); 685 free(fp); 686 ctx.modified = 1; 687 } 688 fclose(ctx.out); 689 ctx.out = NULL; 690 691 if (ctx.modified) { 692 /* Backup the original file and replace it with the temporary */ 693 if (unlink(back) == -1 && errno != ENOENT) { 694 oerrno = errno; 695 error_f("unlink %.100s: %s", back, strerror(errno)); 696 r = SSH_ERR_SYSTEM_ERROR; 697 goto fail; 698 } 699 if (link(filename, back) == -1) { 700 oerrno = errno; 701 error_f("link %.100s to %.100s: %s", filename, 702 back, strerror(errno)); 703 r = SSH_ERR_SYSTEM_ERROR; 704 goto fail; 705 } 706 if (rename(temp, filename) == -1) { 707 oerrno = errno; 708 error_f("rename \"%s\" to \"%s\": %s", temp, 709 filename, strerror(errno)); 710 r = SSH_ERR_SYSTEM_ERROR; 711 goto fail; 712 } 713 } else { 714 /* No changes made; just delete the temporary file */ 715 if (unlink(temp) != 0) 716 error_f("unlink \"%s\": %s", temp, strerror(errno)); 717 } 718 719 /* success */ 720 r = 0; 721 fail: 722 if (temp != NULL && r != 0) 723 unlink(temp); 724 free(temp); 725 free(back); 726 if (ctx.out != NULL) 727 fclose(ctx.out); 728 free(ctx.match_keys); 729 umask(omask); 730 if (r == SSH_ERR_SYSTEM_ERROR) 731 errno = oerrno; 732 return r; 733} 734 735static int 736match_maybe_hashed(const char *host, const char *names, int *was_hashed) 737{ 738 int hashed = *names == HASH_DELIM, ret; 739 char *hashed_host = NULL; 740 size_t nlen = strlen(names); 741 742 if (was_hashed != NULL) 743 *was_hashed = hashed; 744 if (hashed) { 745 if ((hashed_host = host_hash(host, names, nlen)) == NULL) 746 return -1; 747 ret = (nlen == strlen(hashed_host) && 748 strncmp(hashed_host, names, nlen) == 0); 749 free(hashed_host); 750 return ret; 751 } 752 return match_hostname(host, names) == 1; 753} 754 755int 756hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback, 757 void *ctx, const char *host, const char *ip, u_int options, u_int note) 758{ 759 char *line = NULL, ktype[128]; 760 u_long linenum = 0; 761 char *cp, *cp2; 762 u_int kbits; 763 int hashed; 764 int s, r = 0; 765 struct hostkey_foreach_line lineinfo; 766 size_t linesize = 0, l; 767 768 memset(&lineinfo, 0, sizeof(lineinfo)); 769 if (host == NULL && (options & HKF_WANT_MATCH) != 0) 770 return SSH_ERR_INVALID_ARGUMENT; 771 772 while (getline(&line, &linesize, f) != -1) { 773 linenum++; 774 line[strcspn(line, "\n")] = '\0'; 775 776 free(lineinfo.line); 777 sshkey_free(lineinfo.key); 778 memset(&lineinfo, 0, sizeof(lineinfo)); 779 lineinfo.path = path; 780 lineinfo.linenum = linenum; 781 lineinfo.line = xstrdup(line); 782 lineinfo.marker = MRK_NONE; 783 lineinfo.status = HKF_STATUS_OK; 784 lineinfo.keytype = KEY_UNSPEC; 785 lineinfo.note = note; 786 787 /* Skip any leading whitespace, comments and empty lines. */ 788 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 789 ; 790 if (!*cp || *cp == '#' || *cp == '\n') { 791 if ((options & HKF_WANT_MATCH) == 0) { 792 lineinfo.status = HKF_STATUS_COMMENT; 793 if ((r = callback(&lineinfo, ctx)) != 0) 794 break; 795 } 796 continue; 797 } 798 799 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) { 800 verbose_f("invalid marker at %s:%lu", path, linenum); 801 if ((options & HKF_WANT_MATCH) == 0) 802 goto bad; 803 continue; 804 } 805 806 /* Find the end of the host name portion. */ 807 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) 808 ; 809 lineinfo.hosts = cp; 810 *cp2++ = '\0'; 811 812 /* Check if the host name matches. */ 813 if (host != NULL) { 814 if ((s = match_maybe_hashed(host, lineinfo.hosts, 815 &hashed)) == -1) { 816 debug2_f("%s:%ld: bad host hash \"%.32s\"", 817 path, linenum, lineinfo.hosts); 818 goto bad; 819 } 820 if (s == 1) { 821 lineinfo.status = HKF_STATUS_MATCHED; 822 lineinfo.match |= HKF_MATCH_HOST | 823 (hashed ? HKF_MATCH_HOST_HASHED : 0); 824 } 825 /* Try matching IP address if supplied */ 826 if (ip != NULL) { 827 if ((s = match_maybe_hashed(ip, lineinfo.hosts, 828 &hashed)) == -1) { 829 debug2_f("%s:%ld: bad ip hash " 830 "\"%.32s\"", path, linenum, 831 lineinfo.hosts); 832 goto bad; 833 } 834 if (s == 1) { 835 lineinfo.status = HKF_STATUS_MATCHED; 836 lineinfo.match |= HKF_MATCH_IP | 837 (hashed ? HKF_MATCH_IP_HASHED : 0); 838 } 839 } 840 /* 841 * Skip this line if host matching requested and 842 * neither host nor address matched. 843 */ 844 if ((options & HKF_WANT_MATCH) != 0 && 845 lineinfo.status != HKF_STATUS_MATCHED) 846 continue; 847 } 848 849 /* Got a match. Skip host name and any following whitespace */ 850 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 851 ; 852 if (*cp2 == '\0' || *cp2 == '#') { 853 debug2("%s:%ld: truncated before key type", 854 path, linenum); 855 goto bad; 856 } 857 lineinfo.rawkey = cp = cp2; 858 859 if ((options & HKF_WANT_PARSE_KEY) != 0) { 860 /* 861 * Extract the key from the line. This will skip 862 * any leading whitespace. Ignore badly formatted 863 * lines. 864 */ 865 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) { 866 error_f("sshkey_new failed"); 867 r = SSH_ERR_ALLOC_FAIL; 868 break; 869 } 870 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) { 871 goto bad; 872 } 873 lineinfo.keytype = lineinfo.key->type; 874 lineinfo.comment = cp; 875 } else { 876 /* Extract and parse key type */ 877 l = strcspn(lineinfo.rawkey, " \t"); 878 if (l <= 1 || l >= sizeof(ktype) || 879 lineinfo.rawkey[l] == '\0') 880 goto bad; 881 memcpy(ktype, lineinfo.rawkey, l); 882 ktype[l] = '\0'; 883 lineinfo.keytype = sshkey_type_from_name(ktype); 884 885 /* 886 * Assume legacy RSA1 if the first component is a short 887 * decimal number. 888 */ 889 if (lineinfo.keytype == KEY_UNSPEC && l < 8 && 890 strspn(ktype, "0123456789") == l) 891 goto bad; 892 893 /* 894 * Check that something other than whitespace follows 895 * the key type. This won't catch all corruption, but 896 * it does catch trivial truncation. 897 */ 898 cp2 += l; /* Skip past key type */ 899 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++) 900 ; 901 if (*cp2 == '\0' || *cp2 == '#') { 902 debug2("%s:%ld: truncated after key type", 903 path, linenum); 904 lineinfo.keytype = KEY_UNSPEC; 905 } 906 if (lineinfo.keytype == KEY_UNSPEC) { 907 bad: 908 sshkey_free(lineinfo.key); 909 lineinfo.key = NULL; 910 lineinfo.status = HKF_STATUS_INVALID; 911 if ((r = callback(&lineinfo, ctx)) != 0) 912 break; 913 continue; 914 } 915 } 916 if ((r = callback(&lineinfo, ctx)) != 0) 917 break; 918 } 919 sshkey_free(lineinfo.key); 920 free(lineinfo.line); 921 free(line); 922 return r; 923} 924 925int 926hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx, 927 const char *host, const char *ip, u_int options, u_int note) 928{ 929 FILE *f; 930 int r, oerrno; 931 932 if ((f = fopen(path, "r")) == NULL) 933 return SSH_ERR_SYSTEM_ERROR; 934 935 debug3_f("reading file \"%s\"", path); 936 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip, 937 options, note); 938 oerrno = errno; 939 fclose(f); 940 errno = oerrno; 941 return r; 942} 943