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 "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
extract_salt(const char * s,u_int l,u_char * salt,size_t salt_len)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 *
host_hash(const char * host,const char * name_from_hostfile,u_int src_len)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
hostfile_read_key(char ** cpp,u_int * bitsp,struct sshkey * ret)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
check_markers(char ** cpp)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 *
init_hostkeys(void)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
record_hostkey(struct hostkey_foreach_line * l,void * _ctx)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
load_hostkeys_file(struct hostkeys * hostkeys,const char * host,const char * path,FILE * f,u_int note)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
load_hostkeys(struct hostkeys * hostkeys,const char * host,const char * path,u_int note)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
free_hostkeys(struct hostkeys * hostkeys)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
check_key_not_revoked(struct hostkeys * hostkeys,struct sshkey * k)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
check_hostkeys_by_key_or_type(struct hostkeys * hostkeys,struct sshkey * k,int keytype,int nid,const struct hostkey_entry ** found)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
check_key_in_hostkeys(struct hostkeys * hostkeys,struct sshkey * key,const struct hostkey_entry ** found)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
lookup_key_in_hostkeys_by_type(struct hostkeys * hostkeys,int keytype,int nid,const struct hostkey_entry ** found)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
lookup_marker_in_hostkeys(struct hostkeys * hostkeys,int want_marker)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
write_host_entry(FILE * f,const char * host,const char * ip,const struct sshkey * key,int store_hash)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
hostfile_create_user_ssh_dir(const char * filename,int notify)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
add_host_to_hostfile(const char * filename,const char * host,const struct sshkey * key,int store_hash)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, addnl = 0;
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 /* Make sure we have a terminating newline. */
527 if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n')
528 addnl = 1;
529 if (fseek(f, 0L, SEEK_END) != 0 || (addnl && fputc('\n', f) != '\n')) {
530 error("Failed to add terminating newline to %s: %s",
531 filename, strerror(errno));
532 fclose(f);
533 return 0;
534 }
535 success = write_host_entry(f, host, NULL, key, store_hash);
536 fclose(f);
537 return success;
538 }
539
540 struct host_delete_ctx {
541 FILE *out;
542 int quiet;
543 const char *host, *ip;
544 u_int *match_keys; /* mask of HKF_MATCH_* for this key */
545 struct sshkey * const *keys;
546 size_t nkeys;
547 int modified;
548 };
549
550 static int
host_delete(struct hostkey_foreach_line * l,void * _ctx)551 host_delete(struct hostkey_foreach_line *l, void *_ctx)
552 {
553 struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx;
554 int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
555 size_t i;
556
557 /* Don't remove CA and revocation lines */
558 if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) {
559 /*
560 * If this line contains one of the keys that we will be
561 * adding later, then don't change it and mark the key for
562 * skipping.
563 */
564 for (i = 0; i < ctx->nkeys; i++) {
565 if (!sshkey_equal(ctx->keys[i], l->key))
566 continue;
567 ctx->match_keys[i] |= l->match;
568 fprintf(ctx->out, "%s\n", l->line);
569 debug3_f("%s key already at %s:%ld",
570 sshkey_type(l->key), l->path, l->linenum);
571 return 0;
572 }
573
574 /*
575 * Hostname matches and has no CA/revoke marker, delete it
576 * by *not* writing the line to ctx->out.
577 */
578 do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s",
579 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
580 l->path, l->linenum, sshkey_type(l->key), ctx->host);
581 ctx->modified = 1;
582 return 0;
583 }
584 /* Retain non-matching hosts and invalid lines when deleting */
585 if (l->status == HKF_STATUS_INVALID) {
586 do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry",
587 ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
588 l->path, l->linenum);
589 }
590 fprintf(ctx->out, "%s\n", l->line);
591 return 0;
592 }
593
594 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)595 hostfile_replace_entries(const char *filename, const char *host, const char *ip,
596 struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg)
597 {
598 int r, fd, oerrno = 0;
599 int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
600 struct host_delete_ctx ctx;
601 char *fp, *temp = NULL, *back = NULL;
602 const char *what;
603 mode_t omask;
604 size_t i;
605 u_int want;
606
607 omask = umask(077);
608
609 memset(&ctx, 0, sizeof(ctx));
610 ctx.host = host;
611 ctx.ip = ip;
612 ctx.quiet = quiet;
613
614 if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL)
615 return SSH_ERR_ALLOC_FAIL;
616 ctx.keys = keys;
617 ctx.nkeys = nkeys;
618 ctx.modified = 0;
619
620 /*
621 * Prepare temporary file for in-place deletion.
622 */
623 if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 ||
624 (r = asprintf(&back, "%s.old", filename)) == -1) {
625 r = SSH_ERR_ALLOC_FAIL;
626 goto fail;
627 }
628
629 if ((fd = mkstemp(temp)) == -1) {
630 oerrno = errno;
631 error_f("mkstemp: %s", strerror(oerrno));
632 r = SSH_ERR_SYSTEM_ERROR;
633 goto fail;
634 }
635 if ((ctx.out = fdopen(fd, "w")) == NULL) {
636 oerrno = errno;
637 close(fd);
638 error_f("fdopen: %s", strerror(oerrno));
639 r = SSH_ERR_SYSTEM_ERROR;
640 goto fail;
641 }
642
643 /* Remove stale/mismatching entries for the specified host */
644 if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip,
645 HKF_WANT_PARSE_KEY, 0)) != 0) {
646 oerrno = errno;
647 error_fr(r, "hostkeys_foreach");
648 goto fail;
649 }
650
651 /* Re-add the requested keys */
652 want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP);
653 for (i = 0; i < nkeys; i++) {
654 if (keys[i] == NULL || (want & ctx.match_keys[i]) == want)
655 continue;
656 if ((fp = sshkey_fingerprint(keys[i], hash_alg,
657 SSH_FP_DEFAULT)) == NULL) {
658 r = SSH_ERR_ALLOC_FAIL;
659 goto fail;
660 }
661 /* write host/ip */
662 what = "";
663 if (ctx.match_keys[i] == 0) {
664 what = "Adding new key";
665 if (!write_host_entry(ctx.out, host, ip,
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_HOST) {
671 what = "Fixing match (hostname)";
672 if (!write_host_entry(ctx.out, host, NULL,
673 keys[i], store_hash)) {
674 r = SSH_ERR_INTERNAL_ERROR;
675 goto fail;
676 }
677 } else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) {
678 what = "Fixing match (address)";
679 if (!write_host_entry(ctx.out, ip, NULL,
680 keys[i], store_hash)) {
681 r = SSH_ERR_INTERNAL_ERROR;
682 goto fail;
683 }
684 }
685 do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s",
686 quiet ? __func__ : "", quiet ? ": " : "", what,
687 host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename,
688 sshkey_ssh_name(keys[i]), fp);
689 free(fp);
690 ctx.modified = 1;
691 }
692 fclose(ctx.out);
693 ctx.out = NULL;
694
695 if (ctx.modified) {
696 /* Backup the original file and replace it with the temporary */
697 if (unlink(back) == -1 && errno != ENOENT) {
698 oerrno = errno;
699 error_f("unlink %.100s: %s", back, strerror(errno));
700 r = SSH_ERR_SYSTEM_ERROR;
701 goto fail;
702 }
703 if (link(filename, back) == -1) {
704 oerrno = errno;
705 error_f("link %.100s to %.100s: %s", filename,
706 back, strerror(errno));
707 r = SSH_ERR_SYSTEM_ERROR;
708 goto fail;
709 }
710 if (rename(temp, filename) == -1) {
711 oerrno = errno;
712 error_f("rename \"%s\" to \"%s\": %s", temp,
713 filename, strerror(errno));
714 r = SSH_ERR_SYSTEM_ERROR;
715 goto fail;
716 }
717 } else {
718 /* No changes made; just delete the temporary file */
719 if (unlink(temp) != 0)
720 error_f("unlink \"%s\": %s", temp, strerror(errno));
721 }
722
723 /* success */
724 r = 0;
725 fail:
726 if (temp != NULL && r != 0)
727 unlink(temp);
728 free(temp);
729 free(back);
730 if (ctx.out != NULL)
731 fclose(ctx.out);
732 free(ctx.match_keys);
733 umask(omask);
734 if (r == SSH_ERR_SYSTEM_ERROR)
735 errno = oerrno;
736 return r;
737 }
738
739 static int
match_maybe_hashed(const char * host,const char * names,int * was_hashed)740 match_maybe_hashed(const char *host, const char *names, int *was_hashed)
741 {
742 int hashed = *names == HASH_DELIM, ret;
743 char *hashed_host = NULL;
744 size_t nlen = strlen(names);
745
746 if (was_hashed != NULL)
747 *was_hashed = hashed;
748 if (hashed) {
749 if ((hashed_host = host_hash(host, names, nlen)) == NULL)
750 return -1;
751 ret = (nlen == strlen(hashed_host) &&
752 strncmp(hashed_host, names, nlen) == 0);
753 free(hashed_host);
754 return ret;
755 }
756 return match_hostname(host, names) == 1;
757 }
758
759 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)760 hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback,
761 void *ctx, const char *host, const char *ip, u_int options, u_int note)
762 {
763 char *line = NULL, ktype[128];
764 u_long linenum = 0;
765 char *cp, *cp2;
766 u_int kbits;
767 int hashed;
768 int s, r = 0;
769 struct hostkey_foreach_line lineinfo;
770 size_t linesize = 0, l;
771
772 memset(&lineinfo, 0, sizeof(lineinfo));
773 if (host == NULL && (options & HKF_WANT_MATCH) != 0)
774 return SSH_ERR_INVALID_ARGUMENT;
775
776 while (getline(&line, &linesize, f) != -1) {
777 linenum++;
778 line[strcspn(line, "\n")] = '\0';
779
780 free(lineinfo.line);
781 sshkey_free(lineinfo.key);
782 memset(&lineinfo, 0, sizeof(lineinfo));
783 lineinfo.path = path;
784 lineinfo.linenum = linenum;
785 lineinfo.line = xstrdup(line);
786 lineinfo.marker = MRK_NONE;
787 lineinfo.status = HKF_STATUS_OK;
788 lineinfo.keytype = KEY_UNSPEC;
789 lineinfo.note = note;
790
791 /* Skip any leading whitespace, comments and empty lines. */
792 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
793 ;
794 if (!*cp || *cp == '#' || *cp == '\n') {
795 if ((options & HKF_WANT_MATCH) == 0) {
796 lineinfo.status = HKF_STATUS_COMMENT;
797 if ((r = callback(&lineinfo, ctx)) != 0)
798 break;
799 }
800 continue;
801 }
802
803 if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) {
804 verbose_f("invalid marker at %s:%lu", path, linenum);
805 if ((options & HKF_WANT_MATCH) == 0)
806 goto bad;
807 continue;
808 }
809
810 /* Find the end of the host name portion. */
811 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
812 ;
813 lineinfo.hosts = cp;
814 *cp2++ = '\0';
815
816 /* Check if the host name matches. */
817 if (host != NULL) {
818 if ((s = match_maybe_hashed(host, lineinfo.hosts,
819 &hashed)) == -1) {
820 debug2_f("%s:%ld: bad host hash \"%.32s\"",
821 path, linenum, lineinfo.hosts);
822 goto bad;
823 }
824 if (s == 1) {
825 lineinfo.status = HKF_STATUS_MATCHED;
826 lineinfo.match |= HKF_MATCH_HOST |
827 (hashed ? HKF_MATCH_HOST_HASHED : 0);
828 }
829 /* Try matching IP address if supplied */
830 if (ip != NULL) {
831 if ((s = match_maybe_hashed(ip, lineinfo.hosts,
832 &hashed)) == -1) {
833 debug2_f("%s:%ld: bad ip hash "
834 "\"%.32s\"", path, linenum,
835 lineinfo.hosts);
836 goto bad;
837 }
838 if (s == 1) {
839 lineinfo.status = HKF_STATUS_MATCHED;
840 lineinfo.match |= HKF_MATCH_IP |
841 (hashed ? HKF_MATCH_IP_HASHED : 0);
842 }
843 }
844 /*
845 * Skip this line if host matching requested and
846 * neither host nor address matched.
847 */
848 if ((options & HKF_WANT_MATCH) != 0 &&
849 lineinfo.status != HKF_STATUS_MATCHED)
850 continue;
851 }
852
853 /* Got a match. Skip host name and any following whitespace */
854 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
855 ;
856 if (*cp2 == '\0' || *cp2 == '#') {
857 debug2("%s:%ld: truncated before key type",
858 path, linenum);
859 goto bad;
860 }
861 lineinfo.rawkey = cp = cp2;
862
863 if ((options & HKF_WANT_PARSE_KEY) != 0) {
864 /*
865 * Extract the key from the line. This will skip
866 * any leading whitespace. Ignore badly formatted
867 * lines.
868 */
869 if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) {
870 error_f("sshkey_new failed");
871 r = SSH_ERR_ALLOC_FAIL;
872 break;
873 }
874 if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) {
875 goto bad;
876 }
877 lineinfo.keytype = lineinfo.key->type;
878 lineinfo.comment = cp;
879 } else {
880 /* Extract and parse key type */
881 l = strcspn(lineinfo.rawkey, " \t");
882 if (l <= 1 || l >= sizeof(ktype) ||
883 lineinfo.rawkey[l] == '\0')
884 goto bad;
885 memcpy(ktype, lineinfo.rawkey, l);
886 ktype[l] = '\0';
887 lineinfo.keytype = sshkey_type_from_name(ktype);
888
889 /*
890 * Assume legacy RSA1 if the first component is a short
891 * decimal number.
892 */
893 if (lineinfo.keytype == KEY_UNSPEC && l < 8 &&
894 strspn(ktype, "0123456789") == l)
895 goto bad;
896
897 /*
898 * Check that something other than whitespace follows
899 * the key type. This won't catch all corruption, but
900 * it does catch trivial truncation.
901 */
902 cp2 += l; /* Skip past key type */
903 for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
904 ;
905 if (*cp2 == '\0' || *cp2 == '#') {
906 debug2("%s:%ld: truncated after key type",
907 path, linenum);
908 lineinfo.keytype = KEY_UNSPEC;
909 }
910 if (lineinfo.keytype == KEY_UNSPEC) {
911 bad:
912 sshkey_free(lineinfo.key);
913 lineinfo.key = NULL;
914 lineinfo.status = HKF_STATUS_INVALID;
915 if ((r = callback(&lineinfo, ctx)) != 0)
916 break;
917 continue;
918 }
919 }
920 if ((r = callback(&lineinfo, ctx)) != 0)
921 break;
922 }
923 sshkey_free(lineinfo.key);
924 free(lineinfo.line);
925 free(line);
926 return r;
927 }
928
929 int
hostkeys_foreach(const char * path,hostkeys_foreach_fn * callback,void * ctx,const char * host,const char * ip,u_int options,u_int note)930 hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx,
931 const char *host, const char *ip, u_int options, u_int note)
932 {
933 FILE *f;
934 int r, oerrno;
935
936 if ((f = fopen(path, "r")) == NULL)
937 return SSH_ERR_SYSTEM_ERROR;
938
939 debug3_f("reading file \"%s\"", path);
940 r = hostkeys_foreach_file(path, f, callback, ctx, host, ip,
941 options, note);
942 oerrno = errno;
943 fclose(f);
944 errno = oerrno;
945 return r;
946 }
947