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9794d008 | 1 | /* $OpenBSD: hostfile.c,v 1.41 2006/07/05 02:42:09 stevesk 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 <resolv.h> |
cc63c340 | 46 | |
5c63c2ab | 47 | #include <openssl/hmac.h> |
48 | #include <openssl/sha.h> | |
4fe2af09 | 49 | |
4fe2af09 | 50 | #include "match.h" |
4fe2af09 | 51 | #include "key.h" |
52 | #include "hostfile.h" | |
42f11eb2 | 53 | #include "log.h" |
5c63c2ab | 54 | #include "xmalloc.h" |
55 | ||
56 | static int | |
57 | extract_salt(const char *s, u_int l, char *salt, size_t salt_len) | |
58 | { | |
59 | char *p, *b64salt; | |
60 | u_int b64len; | |
61 | int ret; | |
62 | ||
63 | if (l < sizeof(HASH_MAGIC) - 1) { | |
64 | debug2("extract_salt: string too short"); | |
65 | return (-1); | |
66 | } | |
67 | if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { | |
68 | debug2("extract_salt: invalid magic identifier"); | |
69 | return (-1); | |
70 | } | |
71 | s += sizeof(HASH_MAGIC) - 1; | |
72 | l -= sizeof(HASH_MAGIC) - 1; | |
73 | if ((p = memchr(s, HASH_DELIM, l)) == NULL) { | |
74 | debug2("extract_salt: missing salt termination character"); | |
75 | return (-1); | |
76 | } | |
77 | ||
78 | b64len = p - s; | |
79 | /* Sanity check */ | |
80 | if (b64len == 0 || b64len > 1024) { | |
81 | debug2("extract_salt: bad encoded salt length %u", b64len); | |
82 | return (-1); | |
83 | } | |
84 | b64salt = xmalloc(1 + b64len); | |
85 | memcpy(b64salt, s, b64len); | |
86 | b64salt[b64len] = '\0'; | |
87 | ||
88 | ret = __b64_pton(b64salt, salt, salt_len); | |
89 | xfree(b64salt); | |
90 | if (ret == -1) { | |
91 | debug2("extract_salt: salt decode error"); | |
92 | return (-1); | |
93 | } | |
94 | if (ret != SHA_DIGEST_LENGTH) { | |
18f8ef7a | 95 | debug2("extract_salt: expected salt len %d, got %d", |
96 | SHA_DIGEST_LENGTH, ret); | |
5c63c2ab | 97 | return (-1); |
98 | } | |
f8cc7664 | 99 | |
5c63c2ab | 100 | return (0); |
101 | } | |
102 | ||
103 | char * | |
104 | host_hash(const char *host, const char *name_from_hostfile, u_int src_len) | |
105 | { | |
106 | const EVP_MD *md = EVP_sha1(); | |
107 | HMAC_CTX mac_ctx; | |
108 | char salt[256], result[256], uu_salt[512], uu_result[512]; | |
109 | static char encoded[1024]; | |
110 | u_int i, len; | |
111 | ||
112 | len = EVP_MD_size(md); | |
113 | ||
114 | if (name_from_hostfile == NULL) { | |
115 | /* Create new salt */ | |
116 | for (i = 0; i < len; i++) | |
117 | salt[i] = arc4random(); | |
118 | } else { | |
119 | /* Extract salt from known host entry */ | |
120 | if (extract_salt(name_from_hostfile, src_len, salt, | |
121 | sizeof(salt)) == -1) | |
122 | return (NULL); | |
123 | } | |
124 | ||
125 | HMAC_Init(&mac_ctx, salt, len, md); | |
126 | HMAC_Update(&mac_ctx, host, strlen(host)); | |
127 | HMAC_Final(&mac_ctx, result, NULL); | |
128 | HMAC_cleanup(&mac_ctx); | |
129 | ||
f8cc7664 | 130 | if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || |
5c63c2ab | 131 | __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) |
132 | fatal("host_hash: __b64_ntop failed"); | |
133 | ||
134 | snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, | |
135 | HASH_DELIM, uu_result); | |
136 | ||
137 | return (encoded); | |
138 | } | |
8efc0c15 | 139 | |
aa3378df | 140 | /* |
4fe2af09 | 141 | * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the |
142 | * pointer over the key. Skips any whitespace at the beginning and at end. | |
aa3378df | 143 | */ |
8efc0c15 | 144 | |
fb396518 | 145 | int |
1e3b8b07 | 146 | hostfile_read_key(char **cpp, u_int *bitsp, Key *ret) |
8efc0c15 | 147 | { |
5260325f | 148 | char *cp; |
149 | ||
150 | /* Skip leading whitespace. */ | |
aa3378df | 151 | for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) |
152 | ; | |
5260325f | 153 | |
fa08c86b | 154 | if (key_read(ret, &cp) != 1) |
5260325f | 155 | return 0; |
156 | ||
157 | /* Skip trailing whitespace. */ | |
aa3378df | 158 | for (; *cp == ' ' || *cp == '\t'; cp++) |
159 | ; | |
5260325f | 160 | |
161 | /* Return results. */ | |
162 | *cpp = cp; | |
fa08c86b | 163 | *bitsp = key_size(ret); |
5260325f | 164 | return 1; |
8efc0c15 | 165 | } |
166 | ||
396c147e | 167 | static int |
b6c7b7b7 | 168 | hostfile_check_key(int bits, const Key *key, const char *host, const char *filename, int linenum) |
4fe2af09 | 169 | { |
fa08c86b | 170 | if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL) |
4fe2af09 | 171 | return 1; |
172 | if (bits != BN_num_bits(key->rsa->n)) { | |
bbe88b6d | 173 | logit("Warning: %s, line %d: keysize mismatch for host %s: " |
4fe2af09 | 174 | "actual %d vs. announced %d.", |
175 | filename, linenum, host, BN_num_bits(key->rsa->n), bits); | |
bbe88b6d | 176 | logit("Warning: replace %d with %d in %s, line %d.", |
4fe2af09 | 177 | bits, BN_num_bits(key->rsa->n), filename, linenum); |
8efc0c15 | 178 | } |
4fe2af09 | 179 | return 1; |
8efc0c15 | 180 | } |
181 | ||
aa3378df | 182 | /* |
183 | * Checks whether the given host (which must be in all lowercase) is already | |
184 | * in the list of our known hosts. Returns HOST_OK if the host is known and | |
185 | * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED | |
186 | * if the host is known but used to have a different host key. | |
8a48a7ef | 187 | * |
188 | * If no 'key' has been specified and a key of type 'keytype' is known | |
189 | * for the specified host, then HOST_FOUND is returned. | |
aa3378df | 190 | */ |
8efc0c15 | 191 | |
8a48a7ef | 192 | static HostStatus |
193 | check_host_in_hostfile_by_key_or_type(const char *filename, | |
b6c7b7b7 | 194 | const char *host, const Key *key, int keytype, Key *found, int *numret) |
8efc0c15 | 195 | { |
5260325f | 196 | FILE *f; |
197 | char line[8192]; | |
198 | int linenum = 0; | |
d9d49fdb | 199 | u_int kbits; |
5c63c2ab | 200 | char *cp, *cp2, *hashed_host; |
5260325f | 201 | HostStatus end_return; |
202 | ||
8002af61 | 203 | debug3("check_host_in_hostfile: filename %s", filename); |
8a48a7ef | 204 | |
5260325f | 205 | /* Open the file containing the list of known hosts. */ |
206 | f = fopen(filename, "r"); | |
207 | if (!f) | |
208 | return HOST_NEW; | |
209 | ||
aa3378df | 210 | /* |
211 | * Return value when the loop terminates. This is set to | |
212 | * HOST_CHANGED if we have seen a different key for the host and have | |
213 | * not found the proper one. | |
214 | */ | |
5260325f | 215 | end_return = HOST_NEW; |
216 | ||
d9d49fdb | 217 | /* Go through the file. */ |
5260325f | 218 | while (fgets(line, sizeof(line), f)) { |
219 | cp = line; | |
220 | linenum++; | |
221 | ||
aa3378df | 222 | /* Skip any leading whitespace, comments and empty lines. */ |
223 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
224 | ; | |
5260325f | 225 | if (!*cp || *cp == '#' || *cp == '\n') |
226 | continue; | |
227 | ||
228 | /* Find the end of the host name portion. */ | |
aa3378df | 229 | for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) |
230 | ; | |
5260325f | 231 | |
232 | /* Check if the host name matches. */ | |
5c63c2ab | 233 | if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) { |
234 | if (*cp != HASH_DELIM) | |
235 | continue; | |
236 | hashed_host = host_hash(host, cp, (u_int) (cp2 - cp)); | |
237 | if (hashed_host == NULL) { | |
238 | debug("Invalid hashed host line %d of %s", | |
239 | linenum, filename); | |
240 | continue; | |
241 | } | |
242 | if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0) | |
243 | continue; | |
244 | } | |
5260325f | 245 | |
246 | /* Got a match. Skip host name. */ | |
247 | cp = cp2; | |
248 | ||
aa3378df | 249 | /* |
250 | * Extract the key from the line. This will skip any leading | |
251 | * whitespace. Ignore badly formatted lines. | |
252 | */ | |
4fe2af09 | 253 | if (!hostfile_read_key(&cp, &kbits, found)) |
254 | continue; | |
5260325f | 255 | |
1e3b8b07 | 256 | if (numret != NULL) |
257 | *numret = linenum; | |
258 | ||
8a48a7ef | 259 | if (key == NULL) { |
260 | /* we found a key of the requested type */ | |
f8f9ef4d | 261 | if (found->type == keytype) { |
262 | fclose(f); | |
8a48a7ef | 263 | return HOST_FOUND; |
f8f9ef4d | 264 | } |
8a48a7ef | 265 | continue; |
266 | } | |
267 | ||
268 | if (!hostfile_check_key(kbits, found, host, filename, linenum)) | |
269 | continue; | |
270 | ||
5260325f | 271 | /* Check if the current key is the same as the given key. */ |
4fe2af09 | 272 | if (key_equal(key, found)) { |
5260325f | 273 | /* Ok, they match. */ |
8002af61 | 274 | debug3("check_host_in_hostfile: match line %d", linenum); |
5260325f | 275 | fclose(f); |
276 | return HOST_OK; | |
277 | } | |
aa3378df | 278 | /* |
279 | * They do not match. We will continue to go through the | |
280 | * file; however, we note that we will not return that it is | |
281 | * new. | |
282 | */ | |
5260325f | 283 | end_return = HOST_CHANGED; |
8efc0c15 | 284 | } |
5260325f | 285 | /* Clear variables and close the file. */ |
286 | fclose(f); | |
287 | ||
aa3378df | 288 | /* |
289 | * Return either HOST_NEW or HOST_CHANGED, depending on whether we | |
290 | * saw a different key for the host. | |
291 | */ | |
5260325f | 292 | return end_return; |
8efc0c15 | 293 | } |
294 | ||
8a48a7ef | 295 | HostStatus |
b6c7b7b7 | 296 | check_host_in_hostfile(const char *filename, const char *host, const Key *key, |
8a48a7ef | 297 | Key *found, int *numret) |
298 | { | |
299 | if (key == NULL) | |
300 | fatal("no key to look up"); | |
301 | return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0, | |
302 | found, numret)); | |
303 | } | |
304 | ||
305 | int | |
306 | lookup_key_in_hostfile_by_type(const char *filename, const char *host, | |
307 | int keytype, Key *found, int *numret) | |
308 | { | |
309 | return (check_host_in_hostfile_by_key_or_type(filename, host, NULL, | |
310 | keytype, found, numret) == HOST_FOUND); | |
311 | } | |
312 | ||
aa3378df | 313 | /* |
314 | * Appends an entry to the host file. Returns false if the entry could not | |
315 | * be appended. | |
316 | */ | |
8efc0c15 | 317 | |
318 | int | |
f8cc7664 | 319 | add_host_to_hostfile(const char *filename, const char *host, const Key *key, |
5c63c2ab | 320 | int store_hash) |
8efc0c15 | 321 | { |
5260325f | 322 | FILE *f; |
4fe2af09 | 323 | int success = 0; |
a056dfa2 | 324 | char *hashed_host = NULL; |
5c63c2ab | 325 | |
4fe2af09 | 326 | if (key == NULL) |
a306f2dd | 327 | return 1; /* XXX ? */ |
5260325f | 328 | f = fopen(filename, "a"); |
329 | if (!f) | |
330 | return 0; | |
5c63c2ab | 331 | |
332 | if (store_hash) { | |
333 | if ((hashed_host = host_hash(host, NULL, 0)) == NULL) { | |
334 | error("add_host_to_hostfile: host_hash failed"); | |
335 | fclose(f); | |
336 | return 0; | |
337 | } | |
338 | } | |
339 | fprintf(f, "%s ", store_hash ? hashed_host : host); | |
340 | ||
4fe2af09 | 341 | if (key_write(key, f)) { |
4fe2af09 | 342 | success = 1; |
343 | } else { | |
a306f2dd | 344 | error("add_host_to_hostfile: saving key in %s failed", filename); |
5260325f | 345 | } |
a306f2dd | 346 | fprintf(f, "\n"); |
5260325f | 347 | fclose(f); |
4fe2af09 | 348 | return success; |
8efc0c15 | 349 | } |