1 /* $OpenBSD: hostfile.c,v 1.95 2023/02/21 06:48:18 dtucker 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 <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
extract_salt(const char * s,u_int l,u_char * salt,size_t salt_len)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 *
host_hash(const char * host,const char * name_from_hostfile,u_int src_len)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 (number of bits, e, n) or DSA key from a string. Moves the
152 * pointer over the key. Skips any whitespace at the beginning and at end.
153 */
154
155 int
hostfile_read_key(char ** cpp,u_int * bitsp,struct sshkey * ret)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
check_markers(char ** cpp)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 *
init_hostkeys(void)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
record_hostkey(struct hostkey_foreach_line * l,void * _ctx)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
load_hostkeys_file(struct hostkeys * hostkeys,const char * host,const char * path,FILE * f,u_int note)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
load_hostkeys(struct hostkeys * hostkeys,const char * host,const char * path,u_int note)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
free_hostkeys(struct hostkeys * hostkeys)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
check_key_not_revoked(struct hostkeys * hostkeys,struct sshkey * k)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
check_hostkeys_by_key_or_type(struct hostkeys * hostkeys,struct sshkey * k,int keytype,int nid,const struct hostkey_entry ** found)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
check_key_in_hostkeys(struct hostkeys * hostkeys,struct sshkey * key,const struct hostkey_entry ** found)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
lookup_key_in_hostkeys_by_type(struct hostkeys * hostkeys,int keytype,int nid,const struct hostkey_entry ** found)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
lookup_marker_in_hostkeys(struct hostkeys * hostkeys,int want_marker)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
write_host_entry(FILE * f,const char * host,const char * ip,const struct sshkey * key,int store_hash)435 write_host_entry(FILE *f, 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 fprintf(f, "%s ", hashed_host);
451 } else if (ip != NULL)
452 fprintf(f, "%s,%s ", lhost, ip);
453 else {
454 fprintf(f, "%s ", lhost);
455 }
456 free(hashed_host);
457 free(lhost);
458 if ((r = sshkey_write(key, f)) == 0)
459 success = 1;
460 else
461 error_fr(r, "sshkey_write");
462 fputc('\n', f);
463 /* If hashing is enabled, the IP address needs to go on its own line */
464 if (success && store_hash && ip != NULL)
465 success = write_host_entry(f, ip, NULL, key, 1);
466 return success;
467 }
468
469 /*
470 * Create user ~/.ssh directory if it doesn't exist and we want to write to it.
471 * If notify is set, a message will be emitted if the directory is created.
472 */
473 void
hostfile_create_user_ssh_dir(const char * filename,int notify)474 hostfile_create_user_ssh_dir(const char *filename, int notify)
475 {
476 char *dotsshdir = NULL, *p;
477 size_t len;
478 struct stat st;
479
480 if ((p = strrchr(filename, '/')) == NULL)
481 return;
482 len = p - filename;
483 dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid());
484 if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0)
485 goto out; /* not ~/.ssh prefixed */
486 if (stat(dotsshdir, &st) == 0)
487 goto out; /* dir already exists */
488 else if (errno != ENOENT)
489 error("Could not stat %s: %s", dotsshdir, strerror(errno));
490 else {
491 if (mkdir(dotsshdir, 0700) == -1)
492 error("Could not create directory '%.200s' (%s).",
493 dotsshdir, strerror(errno));
494 else if (notify)
495 logit("Created directory '%s'.", dotsshdir);
496 }
497 out:
498 free(dotsshdir);
499 }
500
501
502 /*
503 * Appends an entry to the host file. Returns false if the entry could not
504 * be appended.
505 */
506 int
add_host_to_hostfile(const char * filename,const char * host,const struct sshkey * key,int store_hash)507 add_host_to_hostfile(const char *filename, const char *host,
508 const struct sshkey *key, int store_hash)
509 {
510 FILE *f;
511 int success, addnl = 0;
512
513 if (key == NULL)
514 return 1; /* XXX ? */
515 hostfile_create_user_ssh_dir(filename, 0);
516 f = fopen(filename, "a+");
517 if (!f)
518 return 0;
519 /* Make sure we have a terminating newline. */
520 if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n')
521 addnl = 1;
522 if (fseek(f, 0L, SEEK_END) != 0 || (addnl && fputc('\n', f) != '\n')) {
523 error("Failed to add terminating newline to %s: %s",
524 filename, strerror(errno));
525 fclose(f);
526 return 0;
527 }
528 success = write_host_entry(f, host, NULL, key, store_hash);
529 fclose(f);
530 return success;
531 }
532
533 struct host_delete_ctx {
534 FILE *out;
535 int quiet;
536 const char *host, *ip;
537 u_int *match_keys; /* mask of HKF_MATCH_* for this key */
538 struct sshkey * const *keys;
539 size_t nkeys;
540 int modified;
541 };
542
543 static int
host_delete(struct hostkey_foreach_line * l,void * _ctx)544 host_delete(struct hostkey_foreach_line *l, void *_ctx)
545 {
546 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx;
547 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
548 size_t i;
549
550 /* Don't remove CA and revocation lines */
551 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) {
552 /*
553 * If this line contains one of the keys that we will be
554 * adding later, then don't change it and mark the key for
555 * skipping.
556 */
557 for (i = 0; i < ctx->nkeys; i++) {
558 if (!sshkey_equal(ctx->keys[i], l->key))
559 continue;
560 ctx->match_keys[i] |= l->match;
561 fprintf(ctx->out, "%s\n", l->line);
562 debug3_f("%s key already at %s:%ld",
563 sshkey_type(l->key), l->path, l->linenum);
564 return 0;
565 }
566
567 /*
568 * Hostname matches and has no CA/revoke marker, delete it
569 * by *not* writing the line to ctx->out.
570 */
571 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s",
572 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
573 l->path, l->linenum, sshkey_type(l->key), ctx->host);
574 ctx->modified = 1;
575 return 0;
576 }
577 /* Retain non-matching hosts and invalid lines when deleting */
578 if (l->status == HKF_STATUS_INVALID) {
579 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry",
580 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
581 l->path, l->linenum);
582 }
583 fprintf(ctx->out, "%s\n", l->line);
584 return 0;
585 }
586
587 int
hostfile_replace_entries(const char * filename,const char * host,const char * ip,struct sshkey ** keys,size_t nkeys,int store_hash,int quiet,int hash_alg)588 hostfile_replace_entries(const char *filename, const char *host, const char *ip,
589 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg)
590 {
591 int r, fd, oerrno = 0;
592 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
593 struct host_delete_ctx ctx;
594 char *fp, *temp = NULL, *back = NULL;
595 const char *what;
596 mode_t omask;
597 size_t i;
598 u_int want;
599
600 omask = umask(077);
601
602 memset(&ctx, 0, sizeof(ctx));
603 ctx.host = host;
604 ctx.ip = ip;
605 ctx.quiet = quiet;
606
607 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL)
608 return SSH_ERR_ALLOC_FAIL;
609 ctx.keys = keys;
610 ctx.nkeys = nkeys;
611 ctx.modified = 0;
612
613 /*
614 * Prepare temporary file for in-place deletion.
615 */
616 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 ||
617 (r = asprintf(&back, "%s.old", filename)) == -1) {
618 r = SSH_ERR_ALLOC_FAIL;
619 goto fail;
620 }
621
622 if ((fd = mkstemp(temp)) == -1) {
623 oerrno = errno;
624 error_f("mkstemp: %s", strerror(oerrno));
625 r = SSH_ERR_SYSTEM_ERROR;
626 goto fail;
627 }
628 if ((ctx.out = fdopen(fd, "w")) == NULL) {
629 oerrno = errno;
630 close(fd);
631 error_f("fdopen: %s", strerror(oerrno));
632 r = SSH_ERR_SYSTEM_ERROR;
633 goto fail;
634 }
635
636 /* Remove stale/mismatching entries for the specified host */
637 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip,
638 HKF_WANT_PARSE_KEY, 0)) != 0) {
639 oerrno = errno;
640 error_fr(r, "hostkeys_foreach");
641 goto fail;
642 }
643
644 /* Re-add the requested keys */
645 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP);
646 for (i = 0; i < nkeys; i++) {
647 if (keys[i] == NULL || (want & ctx.match_keys[i]) == want)
648 continue;
649 if ((fp = sshkey_fingerprint(keys[i], hash_alg,
650 SSH_FP_DEFAULT)) == NULL) {
651 r = SSH_ERR_ALLOC_FAIL;
652 goto fail;
653 }
654 /* write host/ip */
655 what = "";
656 if (ctx.match_keys[i] == 0) {
657 what = "Adding new key";
658 if (!write_host_entry(ctx.out, host, ip,
659 keys[i], store_hash)) {
660 r = SSH_ERR_INTERNAL_ERROR;
661 goto fail;
662 }
663 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) {
664 what = "Fixing match (hostname)";
665 if (!write_host_entry(ctx.out, host, NULL,
666 keys[i], store_hash)) {
667 r = SSH_ERR_INTERNAL_ERROR;
668 goto fail;
669 }
670 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) {
671 what = "Fixing match (address)";
672 if (!write_host_entry(ctx.out, ip, NULL,
673 keys[i], store_hash)) {
674 r = SSH_ERR_INTERNAL_ERROR;
675 goto fail;
676 }
677 }
678 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s",
679 quiet ? __func__ : "", quiet ? ": " : "", what,
680 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename,
681 sshkey_ssh_name(keys[i]), fp);
682 free(fp);
683 ctx.modified = 1;
684 }
685 fclose(ctx.out);
686 ctx.out = NULL;
687
688 if (ctx.modified) {
689 /* Backup the original file and replace it with the temporary */
690 if (unlink(back) == -1 && errno != ENOENT) {
691 oerrno = errno;
692 error_f("unlink %.100s: %s", back, strerror(errno));
693 r = SSH_ERR_SYSTEM_ERROR;
694 goto fail;
695 }
696 if (link(filename, back) == -1) {
697 oerrno = errno;
698 error_f("link %.100s to %.100s: %s", filename,
699 back, strerror(errno));
700 r = SSH_ERR_SYSTEM_ERROR;
701 goto fail;
702 }
703 if (rename(temp, filename) == -1) {
704 oerrno = errno;
705 error_f("rename \"%s\" to \"%s\": %s", temp,
706 filename, strerror(errno));
707 r = SSH_ERR_SYSTEM_ERROR;
708 goto fail;
709 }
710 } else {
711 /* No changes made; just delete the temporary file */
712 if (unlink(temp) != 0)
713 error_f("unlink \"%s\": %s", temp, strerror(errno));
714 }
715
716 /* success */
717 r = 0;
718 fail:
719 if (temp != NULL && r != 0)
720 unlink(temp);
721 free(temp);
722 free(back);
723 if (ctx.out != NULL)
724 fclose(ctx.out);
725 free(ctx.match_keys);
726 umask(omask);
727 if (r == SSH_ERR_SYSTEM_ERROR)
728 errno = oerrno;
729 return r;
730 }
731
732 static int
match_maybe_hashed(const char * host,const char * names,int * was_hashed)733 match_maybe_hashed(const char *host, const char *names, int *was_hashed)
734 {
735 int hashed = *names == HASH_DELIM, ret;
736 char *hashed_host = NULL;
737 size_t nlen = strlen(names);
738
739 if (was_hashed != NULL)
740 *was_hashed = hashed;
741 if (hashed) {
742 if ((hashed_host = host_hash(host, names, nlen)) == NULL)
743 return -1;
744 ret = (nlen == strlen(hashed_host) &&
745 strncmp(hashed_host, names, nlen) == 0);
746 free(hashed_host);
747 return ret;
748 }
749 return match_hostname(host, names) == 1;
750 }
751
752 int
hostkeys_foreach_file(const char * path,FILE * f,hostkeys_foreach_fn * callback,void * ctx,const char * host,const char * ip,u_int options,u_int note)753 hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback,
754 void *ctx, const char *host, const char *ip, u_int options, u_int note)
755 {
756 char *line = NULL, ktype[128];
757 u_long linenum = 0;
758 char *cp, *cp2;
759 u_int kbits;
760 int hashed;
761 int s, r = 0;
762 struct hostkey_foreach_line lineinfo;
763 size_t linesize = 0, l;
764
765 memset(&lineinfo, 0, sizeof(lineinfo));
766 if (host == NULL && (options & HKF_WANT_MATCH) != 0)
767 return SSH_ERR_INVALID_ARGUMENT;
768
769 while (getline(&line, &linesize, f) != -1) {
770 linenum++;
771 line[strcspn(line, "\n")] = '\0';
772
773 free(lineinfo.line);
774 sshkey_free(lineinfo.key);
775 memset(&lineinfo, 0, sizeof(lineinfo));
776 lineinfo.path = path;
777 lineinfo.linenum = linenum;
778 lineinfo.line = xstrdup(line);
779 lineinfo.marker = MRK_NONE;
780 lineinfo.status = HKF_STATUS_OK;
781 lineinfo.keytype = KEY_UNSPEC;
782 lineinfo.note = note;
783
784 /* Skip any leading whitespace, comments and empty lines. */
785 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
786 ;
787 if (!*cp || *cp == '#' || *cp == '\n') {
788 if ((options & HKF_WANT_MATCH) == 0) {
789 lineinfo.status = HKF_STATUS_COMMENT;
790 if ((r = callback(&lineinfo, ctx)) != 0)
791 break;
792 }
793 continue;
794 }
795
796 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) {
797 verbose_f("invalid marker at %s:%lu", path, linenum);
798 if ((options & HKF_WANT_MATCH) == 0)
799 goto bad;
800 continue;
801 }
802
803 /* Find the end of the host name portion. */
804 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
805 ;
806 lineinfo.hosts = cp;
807 *cp2++ = '\0';
808
809 /* Check if the host name matches. */
810 if (host != NULL) {
811 if ((s = match_maybe_hashed(host, lineinfo.hosts,
812 &hashed)) == -1) {
813 debug2_f("%s:%ld: bad host hash \"%.32s\"",
814 path, linenum, lineinfo.hosts);
815 goto bad;
816 }
817 if (s == 1) {
818 lineinfo.status = HKF_STATUS_MATCHED;
819 lineinfo.match |= HKF_MATCH_HOST |
820 (hashed ? HKF_MATCH_HOST_HASHED : 0);
821 }
822 /* Try matching IP address if supplied */
823 if (ip != NULL) {
824 if ((s = match_maybe_hashed(ip, lineinfo.hosts,
825 &hashed)) == -1) {
826 debug2_f("%s:%ld: bad ip hash "
827 "\"%.32s\"", path, linenum,
828 lineinfo.hosts);
829 goto bad;
830 }
831 if (s == 1) {
832 lineinfo.status = HKF_STATUS_MATCHED;
833 lineinfo.match |= HKF_MATCH_IP |
834 (hashed ? HKF_MATCH_IP_HASHED : 0);
835 }
836 }
837 /*
838 * Skip this line if host matching requested and
839 * neither host nor address matched.
840 */
841 if ((options & HKF_WANT_MATCH) != 0 &&
842 lineinfo.status != HKF_STATUS_MATCHED)
843 continue;
844 }
845
846 /* Got a match. Skip host name and any following whitespace */
847 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
848 ;
849 if (*cp2 == '\0' || *cp2 == '#') {
850 debug2("%s:%ld: truncated before key type",
851 path, linenum);
852 goto bad;
853 }
854 lineinfo.rawkey = cp = cp2;
855
856 if ((options & HKF_WANT_PARSE_KEY) != 0) {
857 /*
858 * Extract the key from the line. This will skip
859 * any leading whitespace. Ignore badly formatted
860 * lines.
861 */
862 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) {
863 error_f("sshkey_new failed");
864 r = SSH_ERR_ALLOC_FAIL;
865 break;
866 }
867 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) {
868 goto bad;
869 }
870 lineinfo.keytype = lineinfo.key->type;
871 lineinfo.comment = cp;
872 } else {
873 /* Extract and parse key type */
874 l = strcspn(lineinfo.rawkey, " \t");
875 if (l <= 1 || l >= sizeof(ktype) ||
876 lineinfo.rawkey[l] == '\0')
877 goto bad;
878 memcpy(ktype, lineinfo.rawkey, l);
879 ktype[l] = '\0';
880 lineinfo.keytype = sshkey_type_from_name(ktype);
881
882 /*
883 * Assume legacy RSA1 if the first component is a short
884 * decimal number.
885 */
886 if (lineinfo.keytype == KEY_UNSPEC && l < 8 &&
887 strspn(ktype, "0123456789") == l)
888 goto bad;
889
890 /*
891 * Check that something other than whitespace follows
892 * the key type. This won't catch all corruption, but
893 * it does catch trivial truncation.
894 */
895 cp2 += l; /* Skip past key type */
896 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
897 ;
898 if (*cp2 == '\0' || *cp2 == '#') {
899 debug2("%s:%ld: truncated after key type",
900 path, linenum);
901 lineinfo.keytype = KEY_UNSPEC;
902 }
903 if (lineinfo.keytype == KEY_UNSPEC) {
904 bad:
905 sshkey_free(lineinfo.key);
906 lineinfo.key = NULL;
907 lineinfo.status = HKF_STATUS_INVALID;
908 if ((r = callback(&lineinfo, ctx)) != 0)
909 break;
910 continue;
911 }
912 }
913 if ((r = callback(&lineinfo, ctx)) != 0)
914 break;
915 }
916 sshkey_free(lineinfo.key);
917 free(lineinfo.line);
918 free(line);
919 return r;
920 }
921
922 int
hostkeys_foreach(const char * path,hostkeys_foreach_fn * callback,void * ctx,const char * host,const char * ip,u_int options,u_int note)923 hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx,
924 const char *host, const char *ip, u_int options, u_int note)
925 {
926 FILE *f;
927 int r, oerrno;
928
929 if ((f = fopen(path, "r")) == NULL)
930 return SSH_ERR_SYSTEM_ERROR;
931
932 debug3_f("reading file \"%s\"", path);
933 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip,
934 options, note);
935 oerrno = errno;
936 fclose(f);
937 errno = oerrno;
938 return r;
939 }
940