]> andersk Git - openssh.git/blame - hostfile.c
- (dtucker) [contrib/cygwin/ssh-host-config] Add SeTcbPrivilege privilege
[openssh.git] / hostfile.c
CommitLineData
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
59static int
60extract_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
106char *
107host_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 148int
1e3b8b07 149hostfile_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 170static int
b6c7b7b7 171hostfile_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 195static HostStatus
196check_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 298HostStatus
b6c7b7b7 299check_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
308int
309lookup_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
321int
f8cc7664 322add_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}
This page took 0.25932 seconds and 5 git commands to generate.