1 /* $OpenBSD: hostfile.c,v 1.55 2014/01/31 16:39:19 tedu Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Functions for manipulating the known hosts files.
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".
15 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
16 * Copyright (c) 1999 Niels Provos. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
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.
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.
41 #include <sys/types.h>
43 #include <netinet/in.h>
61 struct hostkey_entry *entries;
66 extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len)
72 if (l < sizeof(HASH_MAGIC) - 1) {
73 debug2("extract_salt: string too short");
76 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) {
77 debug2("extract_salt: invalid magic identifier");
80 s += sizeof(HASH_MAGIC) - 1;
81 l -= sizeof(HASH_MAGIC) - 1;
82 if ((p = memchr(s, HASH_DELIM, l)) == NULL) {
83 debug2("extract_salt: missing salt termination character");
89 if (b64len == 0 || b64len > 1024) {
90 debug2("extract_salt: bad encoded salt length %u", b64len);
93 b64salt = xmalloc(1 + b64len);
94 memcpy(b64salt, s, b64len);
95 b64salt[b64len] = '\0';
97 ret = __b64_pton(b64salt, salt, salt_len);
100 debug2("extract_salt: salt decode error");
103 if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) {
104 debug2("extract_salt: expected salt len %zd, got %d",
105 ssh_hmac_bytes(SSH_DIGEST_SHA1), ret);
113 host_hash(const char *host, const char *name_from_hostfile, u_int src_len)
115 struct ssh_hmac_ctx *ctx;
116 u_char salt[256], result[256];
117 char uu_salt[512], uu_result[512];
118 static char encoded[1024];
121 len = ssh_digest_bytes(SSH_DIGEST_SHA1);
123 if (name_from_hostfile == NULL) {
124 /* Create new salt */
125 for (i = 0; i < len; i++)
126 salt[i] = arc4random();
128 /* Extract salt from known host entry */
129 if (extract_salt(name_from_hostfile, src_len, salt,
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("%s: ssh_hmac failed", __func__);
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("%s: __b64_ntop failed", __func__);
145 snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt,
146 HASH_DELIM, uu_result);
152 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
153 * pointer over the key. Skips any whitespace at the beginning and at end.
157 hostfile_read_key(char **cpp, int *bitsp, Key *ret)
161 /* Skip leading whitespace. */
162 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
165 if (key_read(ret, &cp) != 1)
168 /* Skip trailing whitespace. */
169 for (; *cp == ' ' || *cp == '\t'; cp++)
172 /* Return results. */
175 if ((*bitsp = key_size(ret)) <= 0)
182 hostfile_check_key(int bits, const Key *key, const char *host,
183 const char *filename, u_long linenum)
185 if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
187 if (bits != BN_num_bits(key->rsa->n)) {
188 logit("Warning: %s, line %lu: keysize mismatch for host %s: "
189 "actual %d vs. announced %d.",
190 filename, linenum, host, BN_num_bits(key->rsa->n), bits);
191 logit("Warning: replace %d with %d in %s, line %lu.",
192 bits, BN_num_bits(key->rsa->n), filename, linenum);
198 check_markers(char **cpp)
200 char marker[32], *sp, *cp = *cpp;
204 /* Only one marker is allowed */
207 /* Markers are terminated by whitespace */
208 if ((sp = strchr(cp, ' ')) == NULL &&
209 (sp = strchr(cp, '\t')) == NULL)
211 /* Extract marker for comparison */
212 if (sp <= cp + 1 || sp >= cp + sizeof(marker))
214 memcpy(marker, cp, sp - cp);
215 marker[sp - cp] = '\0';
216 if (strcmp(marker, CA_MARKER) == 0)
218 else if (strcmp(marker, REVOKE_MARKER) == 0)
223 /* Skip past marker and any whitespace that follows it */
225 for (; *cp == ' ' || *cp == '\t'; cp++)
235 struct hostkeys *ret = xcalloc(1, sizeof(*ret));
242 load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path)
246 u_long linenum = 0, num_loaded = 0;
247 char *cp, *cp2, *hashed_host;
248 HostkeyMarker marker;
252 if ((f = fopen(path, "r")) == NULL)
254 debug3("%s: loading entries for host \"%.100s\" from file \"%s\"",
255 __func__, host, path);
256 while (read_keyfile_line(f, path, line, sizeof(line), &linenum) == 0) {
259 /* Skip any leading whitespace, comments and empty lines. */
260 for (; *cp == ' ' || *cp == '\t'; cp++)
262 if (!*cp || *cp == '#' || *cp == '\n')
265 if ((marker = check_markers(&cp)) == MRK_ERROR) {
266 verbose("%s: invalid marker at %s:%lu",
267 __func__, path, linenum);
271 /* Find the end of the host name portion. */
272 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
275 /* Check if the host name matches. */
276 if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) {
277 if (*cp != HASH_DELIM)
279 hashed_host = host_hash(host, cp, (u_int) (cp2 - cp));
280 if (hashed_host == NULL) {
281 debug("Invalid hashed host line %lu of %s",
285 if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0)
289 /* Got a match. Skip host name. */
293 * Extract the key from the line. This will skip any leading
294 * whitespace. Ignore badly formatted lines.
296 key = key_new(KEY_UNSPEC);
297 if (!hostfile_read_key(&cp, &kbits, key)) {
299 key = key_new(KEY_RSA1);
300 if (!hostfile_read_key(&cp, &kbits, key)) {
305 if (!hostfile_check_key(kbits, key, host, path, linenum))
308 debug3("%s: found %skey type %s in file %s:%lu", __func__,
309 marker == MRK_NONE ? "" :
310 (marker == MRK_CA ? "ca " : "revoked "),
311 key_type(key), path, linenum);
312 hostkeys->entries = xrealloc(hostkeys->entries,
313 hostkeys->num_entries + 1, sizeof(*hostkeys->entries));
314 hostkeys->entries[hostkeys->num_entries].host = xstrdup(host);
315 hostkeys->entries[hostkeys->num_entries].file = xstrdup(path);
316 hostkeys->entries[hostkeys->num_entries].line = linenum;
317 hostkeys->entries[hostkeys->num_entries].key = key;
318 hostkeys->entries[hostkeys->num_entries].marker = marker;
319 hostkeys->num_entries++;
322 debug3("%s: loaded %lu keys", __func__, num_loaded);
328 free_hostkeys(struct hostkeys *hostkeys)
332 for (i = 0; i < hostkeys->num_entries; i++) {
333 free(hostkeys->entries[i].host);
334 free(hostkeys->entries[i].file);
335 key_free(hostkeys->entries[i].key);
336 explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries));
338 free(hostkeys->entries);
339 explicit_bzero(hostkeys, sizeof(*hostkeys));
344 check_key_not_revoked(struct hostkeys *hostkeys, Key *k)
346 int is_cert = key_is_cert(k);
349 for (i = 0; i < hostkeys->num_entries; i++) {
350 if (hostkeys->entries[i].marker != MRK_REVOKE)
352 if (key_equal_public(k, hostkeys->entries[i].key))
355 key_equal_public(k->cert->signature_key,
356 hostkeys->entries[i].key))
363 * Match keys against a specified key, or look one up by key type.
365 * If looking for a keytype (key == NULL) and one is found then return
366 * HOST_FOUND, otherwise HOST_NEW.
368 * If looking for a key (key != NULL):
369 * 1. If the key is a cert and a matching CA is found, return HOST_OK
370 * 2. If the key is not a cert and a matching key is found, return HOST_OK
371 * 3. If no key matches but a key with a different type is found, then
372 * return HOST_CHANGED
373 * 4. If no matching keys are found, then return HOST_NEW.
375 * Finally, check any found key is not revoked.
378 check_hostkeys_by_key_or_type(struct hostkeys *hostkeys,
379 Key *k, int keytype, const struct hostkey_entry **found)
382 HostStatus end_return = HOST_NEW;
383 int want_cert = key_is_cert(k);
384 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE;
385 int proto = (k ? k->type : keytype) == KEY_RSA1 ? 1 : 2;
390 for (i = 0; i < hostkeys->num_entries; i++) {
391 if (proto == 1 && hostkeys->entries[i].key->type != KEY_RSA1)
393 if (proto == 2 && hostkeys->entries[i].key->type == KEY_RSA1)
395 if (hostkeys->entries[i].marker != want_marker)
398 if (hostkeys->entries[i].key->type != keytype)
400 end_return = HOST_FOUND;
402 *found = hostkeys->entries + i;
403 k = hostkeys->entries[i].key;
407 if (key_equal_public(k->cert->signature_key,
408 hostkeys->entries[i].key)) {
409 /* A matching CA exists */
410 end_return = HOST_OK;
412 *found = hostkeys->entries + i;
416 if (key_equal(k, hostkeys->entries[i].key)) {
417 end_return = HOST_OK;
419 *found = hostkeys->entries + i;
422 /* A non-maching key exists */
423 end_return = HOST_CHANGED;
425 *found = hostkeys->entries + i;
428 if (check_key_not_revoked(hostkeys, k) != 0) {
429 end_return = HOST_REVOKED;
437 check_key_in_hostkeys(struct hostkeys *hostkeys, Key *key,
438 const struct hostkey_entry **found)
441 fatal("no key to look up");
442 return check_hostkeys_by_key_or_type(hostkeys, key, 0, found);
446 lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype,
447 const struct hostkey_entry **found)
449 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype,
450 found) == HOST_FOUND);
454 * Appends an entry to the host file. Returns false if the entry could not
459 add_host_to_hostfile(const char *filename, const char *host, const Key *key,
464 char *hashed_host = NULL;
467 return 1; /* XXX ? */
468 f = fopen(filename, "a");
473 if ((hashed_host = host_hash(host, NULL, 0)) == NULL) {
474 error("add_host_to_hostfile: host_hash failed");
479 fprintf(f, "%s ", store_hash ? hashed_host : host);
481 if (key_write(key, f)) {
484 error("add_host_to_hostfile: saving key in %s failed", filename);