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31652869 | 1 | /* $OpenBSD: hostfile.c,v 1.45 2006/08/03 03:34:42 deraadt Exp $ */ |
8efc0c15 | 2 | /* |
5260325f | 3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
5 | * All rights reserved | |
bcbf86ec | 6 | * Functions for manipulating the known hosts files. |
6ae2364d | 7 | * |
bcbf86ec | 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". | |
6ae2364d | 13 | * |
6ae2364d | 14 | * |
a96070d4 | 15 | * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. |
bcbf86ec | 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. | |
5260325f | 37 | */ |
8efc0c15 | 38 | |
39 | #include "includes.h" | |
5c63c2ab | 40 | |
9794d008 | 41 | #include <sys/types.h> |
42 | ||
43 | #include <netinet/in.h> | |
44 | ||
5c63c2ab | 45 | #include <openssl/hmac.h> |
46 | #include <openssl/sha.h> | |
4fe2af09 | 47 | |
ffa517a8 | 48 | #include <resolv.h> |
cf851879 | 49 | #include <stdio.h> |
ffa517a8 | 50 | #include <stdlib.h> |
51 | #include <string.h> | |
52 | ||
31652869 | 53 | #include "xmalloc.h" |
4fe2af09 | 54 | #include "match.h" |
4fe2af09 | 55 | #include "key.h" |
56 | #include "hostfile.h" | |
42f11eb2 | 57 | #include "log.h" |
5c63c2ab | 58 | |
59 | static int | |
60 | extract_salt(const char *s, u_int l, char *salt, size_t salt_len) | |
61 | { | |
62 | char *p, *b64salt; | |
63 | u_int b64len; | |
64 | int ret; | |
65 | ||
66 | if (l < sizeof(HASH_MAGIC) - 1) { | |
67 | debug2("extract_salt: string too short"); | |
68 | return (-1); | |
69 | } | |
70 | if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { | |
71 | debug2("extract_salt: invalid magic identifier"); | |
72 | return (-1); | |
73 | } | |
74 | s += sizeof(HASH_MAGIC) - 1; | |
75 | l -= sizeof(HASH_MAGIC) - 1; | |
76 | if ((p = memchr(s, HASH_DELIM, l)) == NULL) { | |
77 | debug2("extract_salt: missing salt termination character"); | |
78 | return (-1); | |
79 | } | |
80 | ||
81 | b64len = p - s; | |
82 | /* Sanity check */ | |
83 | if (b64len == 0 || b64len > 1024) { | |
84 | debug2("extract_salt: bad encoded salt length %u", b64len); | |
85 | return (-1); | |
86 | } | |
87 | b64salt = xmalloc(1 + b64len); | |
88 | memcpy(b64salt, s, b64len); | |
89 | b64salt[b64len] = '\0'; | |
90 | ||
91 | ret = __b64_pton(b64salt, salt, salt_len); | |
92 | xfree(b64salt); | |
93 | if (ret == -1) { | |
94 | debug2("extract_salt: salt decode error"); | |
95 | return (-1); | |
96 | } | |
97 | if (ret != SHA_DIGEST_LENGTH) { | |
18f8ef7a | 98 | debug2("extract_salt: expected salt len %d, got %d", |
99 | SHA_DIGEST_LENGTH, ret); | |
5c63c2ab | 100 | return (-1); |
101 | } | |
f8cc7664 | 102 | |
5c63c2ab | 103 | return (0); |
104 | } | |
105 | ||
106 | char * | |
107 | host_hash(const char *host, const char *name_from_hostfile, u_int src_len) | |
108 | { | |
109 | const EVP_MD *md = EVP_sha1(); | |
110 | HMAC_CTX mac_ctx; | |
111 | char salt[256], result[256], uu_salt[512], uu_result[512]; | |
112 | static char encoded[1024]; | |
113 | u_int i, len; | |
114 | ||
115 | len = EVP_MD_size(md); | |
116 | ||
117 | if (name_from_hostfile == NULL) { | |
118 | /* Create new salt */ | |
119 | for (i = 0; i < len; i++) | |
120 | salt[i] = arc4random(); | |
121 | } else { | |
122 | /* Extract salt from known host entry */ | |
123 | if (extract_salt(name_from_hostfile, src_len, salt, | |
124 | sizeof(salt)) == -1) | |
125 | return (NULL); | |
126 | } | |
127 | ||
128 | HMAC_Init(&mac_ctx, salt, len, md); | |
129 | HMAC_Update(&mac_ctx, host, strlen(host)); | |
130 | HMAC_Final(&mac_ctx, result, NULL); | |
131 | HMAC_cleanup(&mac_ctx); | |
132 | ||
f8cc7664 | 133 | if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || |
5c63c2ab | 134 | __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) |
135 | fatal("host_hash: __b64_ntop failed"); | |
136 | ||
137 | snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, | |
138 | HASH_DELIM, uu_result); | |
139 | ||
140 | return (encoded); | |
141 | } | |
8efc0c15 | 142 | |
aa3378df | 143 | /* |
4fe2af09 | 144 | * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the |
145 | * pointer over the key. Skips any whitespace at the beginning and at end. | |
aa3378df | 146 | */ |
8efc0c15 | 147 | |
fb396518 | 148 | int |
1e3b8b07 | 149 | hostfile_read_key(char **cpp, u_int *bitsp, Key *ret) |
8efc0c15 | 150 | { |
5260325f | 151 | char *cp; |
152 | ||
153 | /* Skip leading whitespace. */ | |
aa3378df | 154 | for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) |
155 | ; | |
5260325f | 156 | |
fa08c86b | 157 | if (key_read(ret, &cp) != 1) |
5260325f | 158 | return 0; |
159 | ||
160 | /* Skip trailing whitespace. */ | |
aa3378df | 161 | for (; *cp == ' ' || *cp == '\t'; cp++) |
162 | ; | |
5260325f | 163 | |
164 | /* Return results. */ | |
165 | *cpp = cp; | |
fa08c86b | 166 | *bitsp = key_size(ret); |
5260325f | 167 | return 1; |
8efc0c15 | 168 | } |
169 | ||
396c147e | 170 | static int |
b6c7b7b7 | 171 | hostfile_check_key(int bits, const Key *key, const char *host, const char *filename, int linenum) |
4fe2af09 | 172 | { |
fa08c86b | 173 | if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL) |
4fe2af09 | 174 | return 1; |
175 | if (bits != BN_num_bits(key->rsa->n)) { | |
bbe88b6d | 176 | logit("Warning: %s, line %d: keysize mismatch for host %s: " |
4fe2af09 | 177 | "actual %d vs. announced %d.", |
178 | filename, linenum, host, BN_num_bits(key->rsa->n), bits); | |
bbe88b6d | 179 | logit("Warning: replace %d with %d in %s, line %d.", |
4fe2af09 | 180 | bits, BN_num_bits(key->rsa->n), filename, linenum); |
8efc0c15 | 181 | } |
4fe2af09 | 182 | return 1; |
8efc0c15 | 183 | } |
184 | ||
aa3378df | 185 | /* |
186 | * Checks whether the given host (which must be in all lowercase) is already | |
187 | * in the list of our known hosts. Returns HOST_OK if the host is known and | |
188 | * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED | |
189 | * if the host is known but used to have a different host key. | |
8a48a7ef | 190 | * |
191 | * If no 'key' has been specified and a key of type 'keytype' is known | |
192 | * for the specified host, then HOST_FOUND is returned. | |
aa3378df | 193 | */ |
8efc0c15 | 194 | |
8a48a7ef | 195 | static HostStatus |
196 | check_host_in_hostfile_by_key_or_type(const char *filename, | |
b6c7b7b7 | 197 | const char *host, const Key *key, int keytype, Key *found, int *numret) |
8efc0c15 | 198 | { |
5260325f | 199 | FILE *f; |
200 | char line[8192]; | |
201 | int linenum = 0; | |
d9d49fdb | 202 | u_int kbits; |
5c63c2ab | 203 | char *cp, *cp2, *hashed_host; |
5260325f | 204 | HostStatus end_return; |
205 | ||
8002af61 | 206 | debug3("check_host_in_hostfile: filename %s", filename); |
8a48a7ef | 207 | |
5260325f | 208 | /* Open the file containing the list of known hosts. */ |
209 | f = fopen(filename, "r"); | |
210 | if (!f) | |
211 | return HOST_NEW; | |
212 | ||
aa3378df | 213 | /* |
214 | * Return value when the loop terminates. This is set to | |
215 | * HOST_CHANGED if we have seen a different key for the host and have | |
216 | * not found the proper one. | |
217 | */ | |
5260325f | 218 | end_return = HOST_NEW; |
219 | ||
d9d49fdb | 220 | /* Go through the file. */ |
5260325f | 221 | while (fgets(line, sizeof(line), f)) { |
222 | cp = line; | |
223 | linenum++; | |
224 | ||
aa3378df | 225 | /* Skip any leading whitespace, comments and empty lines. */ |
226 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
227 | ; | |
5260325f | 228 | if (!*cp || *cp == '#' || *cp == '\n') |
229 | continue; | |
230 | ||
231 | /* Find the end of the host name portion. */ | |
aa3378df | 232 | for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) |
233 | ; | |
5260325f | 234 | |
235 | /* Check if the host name matches. */ | |
5c63c2ab | 236 | if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) { |
237 | if (*cp != HASH_DELIM) | |
238 | continue; | |
239 | hashed_host = host_hash(host, cp, (u_int) (cp2 - cp)); | |
240 | if (hashed_host == NULL) { | |
241 | debug("Invalid hashed host line %d of %s", | |
242 | linenum, filename); | |
243 | continue; | |
244 | } | |
245 | if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0) | |
246 | continue; | |
247 | } | |
5260325f | 248 | |
249 | /* Got a match. Skip host name. */ | |
250 | cp = cp2; | |
251 | ||
aa3378df | 252 | /* |
253 | * Extract the key from the line. This will skip any leading | |
254 | * whitespace. Ignore badly formatted lines. | |
255 | */ | |
4fe2af09 | 256 | if (!hostfile_read_key(&cp, &kbits, found)) |
257 | continue; | |
5260325f | 258 | |
1e3b8b07 | 259 | if (numret != NULL) |
260 | *numret = linenum; | |
261 | ||
8a48a7ef | 262 | if (key == NULL) { |
263 | /* we found a key of the requested type */ | |
f8f9ef4d | 264 | if (found->type == keytype) { |
265 | fclose(f); | |
8a48a7ef | 266 | return HOST_FOUND; |
f8f9ef4d | 267 | } |
8a48a7ef | 268 | continue; |
269 | } | |
270 | ||
271 | if (!hostfile_check_key(kbits, found, host, filename, linenum)) | |
272 | continue; | |
273 | ||
5260325f | 274 | /* Check if the current key is the same as the given key. */ |
4fe2af09 | 275 | if (key_equal(key, found)) { |
5260325f | 276 | /* Ok, they match. */ |
8002af61 | 277 | debug3("check_host_in_hostfile: match line %d", linenum); |
5260325f | 278 | fclose(f); |
279 | return HOST_OK; | |
280 | } | |
aa3378df | 281 | /* |
282 | * They do not match. We will continue to go through the | |
283 | * file; however, we note that we will not return that it is | |
284 | * new. | |
285 | */ | |
5260325f | 286 | end_return = HOST_CHANGED; |
8efc0c15 | 287 | } |
5260325f | 288 | /* Clear variables and close the file. */ |
289 | fclose(f); | |
290 | ||
aa3378df | 291 | /* |
292 | * Return either HOST_NEW or HOST_CHANGED, depending on whether we | |
293 | * saw a different key for the host. | |
294 | */ | |
5260325f | 295 | return end_return; |
8efc0c15 | 296 | } |
297 | ||
8a48a7ef | 298 | HostStatus |
b6c7b7b7 | 299 | check_host_in_hostfile(const char *filename, const char *host, const Key *key, |
8a48a7ef | 300 | Key *found, int *numret) |
301 | { | |
302 | if (key == NULL) | |
303 | fatal("no key to look up"); | |
304 | return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0, | |
305 | found, numret)); | |
306 | } | |
307 | ||
308 | int | |
309 | lookup_key_in_hostfile_by_type(const char *filename, const char *host, | |
310 | int keytype, Key *found, int *numret) | |
311 | { | |
312 | return (check_host_in_hostfile_by_key_or_type(filename, host, NULL, | |
313 | keytype, found, numret) == HOST_FOUND); | |
314 | } | |
315 | ||
aa3378df | 316 | /* |
317 | * Appends an entry to the host file. Returns false if the entry could not | |
318 | * be appended. | |
319 | */ | |
8efc0c15 | 320 | |
321 | int | |
f8cc7664 | 322 | add_host_to_hostfile(const char *filename, const char *host, const Key *key, |
5c63c2ab | 323 | int store_hash) |
8efc0c15 | 324 | { |
5260325f | 325 | FILE *f; |
4fe2af09 | 326 | int success = 0; |
a056dfa2 | 327 | char *hashed_host = NULL; |
5c63c2ab | 328 | |
4fe2af09 | 329 | if (key == NULL) |
a306f2dd | 330 | return 1; /* XXX ? */ |
5260325f | 331 | f = fopen(filename, "a"); |
332 | if (!f) | |
333 | return 0; | |
5c63c2ab | 334 | |
335 | if (store_hash) { | |
336 | if ((hashed_host = host_hash(host, NULL, 0)) == NULL) { | |
337 | error("add_host_to_hostfile: host_hash failed"); | |
338 | fclose(f); | |
339 | return 0; | |
340 | } | |
341 | } | |
342 | fprintf(f, "%s ", store_hash ? hashed_host : host); | |
343 | ||
4fe2af09 | 344 | if (key_write(key, f)) { |
4fe2af09 | 345 | success = 1; |
346 | } else { | |
a306f2dd | 347 | error("add_host_to_hostfile: saving key in %s failed", filename); |
5260325f | 348 | } |
a306f2dd | 349 | fprintf(f, "\n"); |
5260325f | 350 | fclose(f); |
4fe2af09 | 351 | return success; |
8efc0c15 | 352 | } |