1 /* $OpenBSD: hostfile.c,v 1.42 2006/07/22 20:48:23 stevesk 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>
48 #include <openssl/hmac.h>
49 #include <openssl/sha.h>
58 extract_salt(const char *s, u_int l, char *salt, size_t salt_len)
64 if (l < sizeof(HASH_MAGIC) - 1) {
65 debug2("extract_salt: string too short");
68 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) {
69 debug2("extract_salt: invalid magic identifier");
72 s += sizeof(HASH_MAGIC) - 1;
73 l -= sizeof(HASH_MAGIC) - 1;
74 if ((p = memchr(s, HASH_DELIM, l)) == NULL) {
75 debug2("extract_salt: missing salt termination character");
81 if (b64len == 0 || b64len > 1024) {
82 debug2("extract_salt: bad encoded salt length %u", b64len);
85 b64salt = xmalloc(1 + b64len);
86 memcpy(b64salt, s, b64len);
87 b64salt[b64len] = '\0';
89 ret = __b64_pton(b64salt, salt, salt_len);
92 debug2("extract_salt: salt decode error");
95 if (ret != SHA_DIGEST_LENGTH) {
96 debug2("extract_salt: expected salt len %d, got %d",
97 SHA_DIGEST_LENGTH, ret);
105 host_hash(const char *host, const char *name_from_hostfile, u_int src_len)
107 const EVP_MD *md = EVP_sha1();
109 char salt[256], result[256], uu_salt[512], uu_result[512];
110 static char encoded[1024];
113 len = EVP_MD_size(md);
115 if (name_from_hostfile == NULL) {
116 /* Create new salt */
117 for (i = 0; i < len; i++)
118 salt[i] = arc4random();
120 /* Extract salt from known host entry */
121 if (extract_salt(name_from_hostfile, src_len, salt,
126 HMAC_Init(&mac_ctx, salt, len, md);
127 HMAC_Update(&mac_ctx, host, strlen(host));
128 HMAC_Final(&mac_ctx, result, NULL);
129 HMAC_cleanup(&mac_ctx);
131 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 ||
132 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1)
133 fatal("host_hash: __b64_ntop failed");
135 snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt,
136 HASH_DELIM, uu_result);
142 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
143 * pointer over the key. Skips any whitespace at the beginning and at end.
147 hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
151 /* Skip leading whitespace. */
152 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
155 if (key_read(ret, &cp) != 1)
158 /* Skip trailing whitespace. */
159 for (; *cp == ' ' || *cp == '\t'; cp++)
162 /* Return results. */
164 *bitsp = key_size(ret);
169 hostfile_check_key(int bits, const Key *key, const char *host, const char *filename, int linenum)
171 if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
173 if (bits != BN_num_bits(key->rsa->n)) {
174 logit("Warning: %s, line %d: keysize mismatch for host %s: "
175 "actual %d vs. announced %d.",
176 filename, linenum, host, BN_num_bits(key->rsa->n), bits);
177 logit("Warning: replace %d with %d in %s, line %d.",
178 bits, BN_num_bits(key->rsa->n), filename, linenum);
184 * Checks whether the given host (which must be in all lowercase) is already
185 * in the list of our known hosts. Returns HOST_OK if the host is known and
186 * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
187 * if the host is known but used to have a different host key.
189 * If no 'key' has been specified and a key of type 'keytype' is known
190 * for the specified host, then HOST_FOUND is returned.
194 check_host_in_hostfile_by_key_or_type(const char *filename,
195 const char *host, const Key *key, int keytype, Key *found, int *numret)
201 char *cp, *cp2, *hashed_host;
202 HostStatus end_return;
204 debug3("check_host_in_hostfile: filename %s", filename);
206 /* Open the file containing the list of known hosts. */
207 f = fopen(filename, "r");
212 * Return value when the loop terminates. This is set to
213 * HOST_CHANGED if we have seen a different key for the host and have
214 * not found the proper one.
216 end_return = HOST_NEW;
218 /* Go through the file. */
219 while (fgets(line, sizeof(line), f)) {
223 /* Skip any leading whitespace, comments and empty lines. */
224 for (; *cp == ' ' || *cp == '\t'; cp++)
226 if (!*cp || *cp == '#' || *cp == '\n')
229 /* Find the end of the host name portion. */
230 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
233 /* Check if the host name matches. */
234 if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) {
235 if (*cp != HASH_DELIM)
237 hashed_host = host_hash(host, cp, (u_int) (cp2 - cp));
238 if (hashed_host == NULL) {
239 debug("Invalid hashed host line %d of %s",
243 if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0)
247 /* Got a match. Skip host name. */
251 * Extract the key from the line. This will skip any leading
252 * whitespace. Ignore badly formatted lines.
254 if (!hostfile_read_key(&cp, &kbits, found))
261 /* we found a key of the requested type */
262 if (found->type == keytype) {
269 if (!hostfile_check_key(kbits, found, host, filename, linenum))
272 /* Check if the current key is the same as the given key. */
273 if (key_equal(key, found)) {
274 /* Ok, they match. */
275 debug3("check_host_in_hostfile: match line %d", linenum);
280 * They do not match. We will continue to go through the
281 * file; however, we note that we will not return that it is
284 end_return = HOST_CHANGED;
286 /* Clear variables and close the file. */
290 * Return either HOST_NEW or HOST_CHANGED, depending on whether we
291 * saw a different key for the host.
297 check_host_in_hostfile(const char *filename, const char *host, const Key *key,
298 Key *found, int *numret)
301 fatal("no key to look up");
302 return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0,
307 lookup_key_in_hostfile_by_type(const char *filename, const char *host,
308 int keytype, Key *found, int *numret)
310 return (check_host_in_hostfile_by_key_or_type(filename, host, NULL,
311 keytype, found, numret) == HOST_FOUND);
315 * Appends an entry to the host file. Returns false if the entry could not
320 add_host_to_hostfile(const char *filename, const char *host, const Key *key,
325 char *hashed_host = NULL;
328 return 1; /* XXX ? */
329 f = fopen(filename, "a");
334 if ((hashed_host = host_hash(host, NULL, 0)) == NULL) {
335 error("add_host_to_hostfile: host_hash failed");
340 fprintf(f, "%s ", store_hash ? hashed_host : host);
342 if (key_write(key, f)) {
345 error("add_host_to_hostfile: saving key in %s failed", filename);