1 /* $OpenBSD: hostfile.c,v 1.50 2010/12/04 13:31:37 djm 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>
45 #include <openssl/hmac.h>
46 #include <openssl/sha.h>
62 struct hostkey_entry *entries;
67 extract_salt(const char *s, u_int l, char *salt, size_t salt_len)
73 if (l < sizeof(HASH_MAGIC) - 1) {
74 debug2("extract_salt: string too short");
77 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) {
78 debug2("extract_salt: invalid magic identifier");
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");
90 if (b64len == 0 || b64len > 1024) {
91 debug2("extract_salt: bad encoded salt length %u", b64len);
94 b64salt = xmalloc(1 + b64len);
95 memcpy(b64salt, s, b64len);
96 b64salt[b64len] = '\0';
98 ret = __b64_pton(b64salt, salt, salt_len);
101 debug2("extract_salt: salt decode error");
104 if (ret != SHA_DIGEST_LENGTH) {
105 debug2("extract_salt: expected salt len %d, got %d",
106 SHA_DIGEST_LENGTH, ret);
114 host_hash(const char *host, const char *name_from_hostfile, u_int src_len)
116 const EVP_MD *md = EVP_sha1();
118 char salt[256], result[256], uu_salt[512], uu_result[512];
119 static char encoded[1024];
122 len = EVP_MD_size(md);
124 if (name_from_hostfile == NULL) {
125 /* Create new salt */
126 for (i = 0; i < len; i++)
127 salt[i] = arc4random();
129 /* Extract salt from known host entry */
130 if (extract_salt(name_from_hostfile, src_len, salt,
135 HMAC_Init(&mac_ctx, salt, len, md);
136 HMAC_Update(&mac_ctx, host, strlen(host));
137 HMAC_Final(&mac_ctx, result, NULL);
138 HMAC_cleanup(&mac_ctx);
140 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 ||
141 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1)
142 fatal("host_hash: __b64_ntop failed");
144 snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt,
145 HASH_DELIM, uu_result);
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.
156 hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
160 /* Skip leading whitespace. */
161 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
164 if (key_read(ret, &cp) != 1)
167 /* Skip trailing whitespace. */
168 for (; *cp == ' ' || *cp == '\t'; cp++)
171 /* Return results. */
174 *bitsp = key_size(ret);
179 hostfile_check_key(int bits, const Key *key, const char *host,
180 const char *filename, u_long linenum)
182 if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
184 if (bits != BN_num_bits(key->rsa->n)) {
185 logit("Warning: %s, line %lu: keysize mismatch for host %s: "
186 "actual %d vs. announced %d.",
187 filename, linenum, host, BN_num_bits(key->rsa->n), bits);
188 logit("Warning: replace %d with %d in %s, line %lu.",
189 bits, BN_num_bits(key->rsa->n), filename, linenum);
195 check_markers(char **cpp)
197 char marker[32], *sp, *cp = *cpp;
201 /* Only one marker is allowed */
204 /* Markers are terminated by whitespace */
205 if ((sp = strchr(cp, ' ')) == NULL &&
206 (sp = strchr(cp, '\t')) == NULL)
208 /* Extract marker for comparison */
209 if (sp <= cp + 1 || sp >= cp + sizeof(marker))
211 memcpy(marker, cp, sp - cp);
212 marker[sp - cp] = '\0';
213 if (strcmp(marker, CA_MARKER) == 0)
215 else if (strcmp(marker, REVOKE_MARKER) == 0)
220 /* Skip past marker and any whitespace that follows it */
222 for (; *cp == ' ' || *cp == '\t'; cp++)
232 struct hostkeys *ret = xcalloc(1, sizeof(*ret));
239 load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path)
243 u_long linenum = 0, num_loaded = 0;
244 char *cp, *cp2, *hashed_host;
245 HostkeyMarker marker;
249 if ((f = fopen(path, "r")) == NULL)
251 debug3("%s: loading entries for host \"%.100s\" from file \"%s\"",
252 __func__, host, path);
253 while (read_keyfile_line(f, path, line, sizeof(line), &linenum) == 0) {
256 /* Skip any leading whitespace, comments and empty lines. */
257 for (; *cp == ' ' || *cp == '\t'; cp++)
259 if (!*cp || *cp == '#' || *cp == '\n')
262 if ((marker = check_markers(&cp)) == MRK_ERROR) {
263 verbose("%s: invalid marker at %s:%lu",
264 __func__, path, linenum);
268 /* Find the end of the host name portion. */
269 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
272 /* Check if the host name matches. */
273 if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) {
274 if (*cp != HASH_DELIM)
276 hashed_host = host_hash(host, cp, (u_int) (cp2 - cp));
277 if (hashed_host == NULL) {
278 debug("Invalid hashed host line %lu of %s",
282 if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0)
286 /* Got a match. Skip host name. */
290 * Extract the key from the line. This will skip any leading
291 * whitespace. Ignore badly formatted lines.
293 key = key_new(KEY_UNSPEC);
294 if (!hostfile_read_key(&cp, &kbits, key)) {
296 key = key_new(KEY_RSA1);
297 if (!hostfile_read_key(&cp, &kbits, key)) {
302 if (!hostfile_check_key(kbits, key, host, path, linenum))
305 debug3("%s: found %skey type %s in file %s:%lu", __func__,
306 marker == MRK_NONE ? "" :
307 (marker == MRK_CA ? "ca " : "revoked "),
308 key_type(key), path, linenum);
309 hostkeys->entries = xrealloc(hostkeys->entries,
310 hostkeys->num_entries + 1, sizeof(*hostkeys->entries));
311 hostkeys->entries[hostkeys->num_entries].host = xstrdup(host);
312 hostkeys->entries[hostkeys->num_entries].file = xstrdup(path);
313 hostkeys->entries[hostkeys->num_entries].line = linenum;
314 hostkeys->entries[hostkeys->num_entries].key = key;
315 hostkeys->entries[hostkeys->num_entries].marker = marker;
316 hostkeys->num_entries++;
319 debug3("%s: loaded %lu keys", __func__, num_loaded);
325 free_hostkeys(struct hostkeys *hostkeys)
329 for (i = 0; i < hostkeys->num_entries; i++) {
330 xfree(hostkeys->entries[i].host);
331 xfree(hostkeys->entries[i].file);
332 key_free(hostkeys->entries[i].key);
333 bzero(hostkeys->entries + i, sizeof(*hostkeys->entries));
335 if (hostkeys->entries != NULL)
336 xfree(hostkeys->entries);
337 hostkeys->entries = NULL;
338 hostkeys->num_entries = 0;
343 check_key_not_revoked(struct hostkeys *hostkeys, Key *k)
345 int is_cert = key_is_cert(k);
348 for (i = 0; i < hostkeys->num_entries; i++) {
349 if (hostkeys->entries[i].marker != MRK_REVOKE)
351 if (key_equal_public(k, hostkeys->entries[i].key))
354 key_equal_public(k->cert->signature_key,
355 hostkeys->entries[i].key))
362 * Match keys against a specified key, or look one up by key type.
364 * If looking for a keytype (key == NULL) and one is found then return
365 * HOST_FOUND, otherwise HOST_NEW.
367 * If looking for a key (key != NULL):
368 * 1. If the key is a cert and a matching CA is found, return HOST_OK
369 * 2. If the key is not a cert and a matching key is found, return HOST_OK
370 * 3. If no key matches but a key with a different type is found, then
371 * return HOST_CHANGED
372 * 4. If no matching keys are found, then return HOST_NEW.
374 * Finally, check any found key is not revoked.
377 check_hostkeys_by_key_or_type(struct hostkeys *hostkeys,
378 Key *k, int keytype, const struct hostkey_entry **found)
381 HostStatus end_return = HOST_NEW;
382 int want_cert = key_is_cert(k);
383 HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE;
384 int proto = (k ? k->type : keytype) == KEY_RSA1 ? 1 : 2;
389 for (i = 0; i < hostkeys->num_entries; i++) {
390 if (proto == 1 && hostkeys->entries[i].key->type != KEY_RSA1)
392 if (proto == 2 && hostkeys->entries[i].key->type == KEY_RSA1)
394 if (hostkeys->entries[i].marker != want_marker)
397 if (hostkeys->entries[i].key->type != keytype)
399 end_return = HOST_FOUND;
401 *found = hostkeys->entries + i;
402 k = hostkeys->entries[i].key;
406 if (key_equal_public(k->cert->signature_key,
407 hostkeys->entries[i].key)) {
408 /* A matching CA exists */
409 end_return = HOST_OK;
411 *found = hostkeys->entries + i;
415 if (key_equal(k, hostkeys->entries[i].key)) {
416 end_return = HOST_OK;
418 *found = hostkeys->entries + i;
421 /* A non-maching key exists */
422 end_return = HOST_CHANGED;
424 *found = hostkeys->entries + i;
427 if (check_key_not_revoked(hostkeys, k) != 0) {
428 end_return = HOST_REVOKED;
436 check_key_in_hostkeys(struct hostkeys *hostkeys, Key *key,
437 const struct hostkey_entry **found)
440 fatal("no key to look up");
441 return check_hostkeys_by_key_or_type(hostkeys, key, 0, found);
445 lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype,
446 const struct hostkey_entry **found)
448 return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype,
449 found) == HOST_FOUND);
453 * Appends an entry to the host file. Returns false if the entry could not
458 add_host_to_hostfile(const char *filename, const char *host, const Key *key,
463 char *hashed_host = NULL;
466 return 1; /* XXX ? */
467 f = fopen(filename, "a");
472 if ((hashed_host = host_hash(host, NULL, 0)) == NULL) {
473 error("add_host_to_hostfile: host_hash failed");
478 fprintf(f, "%s ", store_hash ? hashed_host : host);
480 if (key_write(key, f)) {
483 error("add_host_to_hostfile: saving key in %s failed", filename);