blob: cd28bf446c6817b30225c0635804c385d2ce940b [file] [log] [blame]
Darren Tucker1b118882009-10-24 11:40:32 +11001/* $OpenBSD: hostfile.c,v 1.46 2009/10/11 23:03:15 djm Exp $ */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10002/*
Damien Miller95def091999-11-25 00:26:21 +11003 * Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller95def091999-11-25 00:26:21 +11004 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11006 * Functions for manipulating the known hosts files.
Damien Miller4af51302000-04-16 11:18:38 +10007 *
Damien Millere4340be2000-09-16 13:29:08 +11008 * 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".
13 *
14 *
Ben Lindstrom44697232001-07-04 03:32:30 +000015 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
Damien Millere4340be2000-09-16 13:29:08 +110016 * 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.
Damien Miller95def091999-11-25 00:26:21 +110037 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100038
39#include "includes.h"
Damien Millere1776152005-03-01 21:47:37 +110040
Damien Miller8ec8c3e2006-07-10 20:35:38 +100041#include <sys/types.h>
42
43#include <netinet/in.h>
44
Damien Millere1776152005-03-01 21:47:37 +110045#include <openssl/hmac.h>
46#include <openssl/sha.h>
Damien Miller450a7a12000-03-26 13:04:51 +100047
Damien Millere7a1e5c2006-08-05 11:34:19 +100048#include <resolv.h>
Damien Millerded319c2006-09-01 15:38:36 +100049#include <stdarg.h>
Damien Millera7a73ee2006-08-05 11:37:59 +100050#include <stdio.h>
Damien Millere7a1e5c2006-08-05 11:34:19 +100051#include <stdlib.h>
52#include <string.h>
53
Damien Millerd7834352006-08-05 12:39:39 +100054#include "xmalloc.h"
Damien Miller450a7a12000-03-26 13:04:51 +100055#include "match.h"
Damien Miller450a7a12000-03-26 13:04:51 +100056#include "key.h"
57#include "hostfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000058#include "log.h"
Damien Millere1776152005-03-01 21:47:37 +110059
60static int
61extract_salt(const char *s, u_int l, char *salt, size_t salt_len)
62{
63 char *p, *b64salt;
64 u_int b64len;
65 int ret;
66
67 if (l < sizeof(HASH_MAGIC) - 1) {
68 debug2("extract_salt: string too short");
69 return (-1);
70 }
71 if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) {
72 debug2("extract_salt: invalid magic identifier");
73 return (-1);
74 }
75 s += sizeof(HASH_MAGIC) - 1;
76 l -= sizeof(HASH_MAGIC) - 1;
77 if ((p = memchr(s, HASH_DELIM, l)) == NULL) {
78 debug2("extract_salt: missing salt termination character");
79 return (-1);
80 }
81
82 b64len = p - s;
83 /* Sanity check */
84 if (b64len == 0 || b64len > 1024) {
85 debug2("extract_salt: bad encoded salt length %u", b64len);
86 return (-1);
87 }
88 b64salt = xmalloc(1 + b64len);
89 memcpy(b64salt, s, b64len);
90 b64salt[b64len] = '\0';
91
92 ret = __b64_pton(b64salt, salt, salt_len);
93 xfree(b64salt);
94 if (ret == -1) {
95 debug2("extract_salt: salt decode error");
96 return (-1);
97 }
98 if (ret != SHA_DIGEST_LENGTH) {
Darren Tucker593bae72005-11-22 19:43:26 +110099 debug2("extract_salt: expected salt len %d, got %d",
100 SHA_DIGEST_LENGTH, ret);
Damien Millere1776152005-03-01 21:47:37 +1100101 return (-1);
102 }
Darren Tucker47eede72005-03-14 23:08:12 +1100103
Damien Millere1776152005-03-01 21:47:37 +1100104 return (0);
105}
106
107char *
108host_hash(const char *host, const char *name_from_hostfile, u_int src_len)
109{
110 const EVP_MD *md = EVP_sha1();
111 HMAC_CTX mac_ctx;
112 char salt[256], result[256], uu_salt[512], uu_result[512];
113 static char encoded[1024];
114 u_int i, len;
115
116 len = EVP_MD_size(md);
117
118 if (name_from_hostfile == NULL) {
119 /* Create new salt */
120 for (i = 0; i < len; i++)
121 salt[i] = arc4random();
122 } else {
123 /* Extract salt from known host entry */
124 if (extract_salt(name_from_hostfile, src_len, salt,
125 sizeof(salt)) == -1)
126 return (NULL);
127 }
128
129 HMAC_Init(&mac_ctx, salt, len, md);
130 HMAC_Update(&mac_ctx, host, strlen(host));
131 HMAC_Final(&mac_ctx, result, NULL);
132 HMAC_cleanup(&mac_ctx);
133
Darren Tucker47eede72005-03-14 23:08:12 +1100134 if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 ||
Damien Millere1776152005-03-01 21:47:37 +1100135 __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1)
136 fatal("host_hash: __b64_ntop failed");
137
138 snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt,
139 HASH_DELIM, uu_result);
140
141 return (encoded);
142}
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000143
Damien Miller5428f641999-11-25 11:54:57 +1100144/*
Damien Miller450a7a12000-03-26 13:04:51 +1000145 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
146 * pointer over the key. Skips any whitespace at the beginning and at end.
Damien Miller5428f641999-11-25 11:54:57 +1100147 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000148
Damien Miller5b2aea92001-12-21 12:47:09 +1100149int
Ben Lindstrom46c16222000-12-22 01:43:59 +0000150hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000151{
Damien Miller95def091999-11-25 00:26:21 +1100152 char *cp;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000153
Damien Miller95def091999-11-25 00:26:21 +1100154 /* Skip leading whitespace. */
Damien Miller5428f641999-11-25 11:54:57 +1100155 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
156 ;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000157
Damien Miller0bc1bd82000-11-13 22:57:25 +1100158 if (key_read(ret, &cp) != 1)
Damien Miller95def091999-11-25 00:26:21 +1100159 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000160
Damien Miller95def091999-11-25 00:26:21 +1100161 /* Skip trailing whitespace. */
Damien Miller5428f641999-11-25 11:54:57 +1100162 for (; *cp == ' ' || *cp == '\t'; cp++)
163 ;
Damien Miller95def091999-11-25 00:26:21 +1100164
165 /* Return results. */
166 *cpp = cp;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100167 *bitsp = key_size(ret);
Damien Miller95def091999-11-25 00:26:21 +1100168 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000169}
170
Ben Lindstrombba81212001-06-25 05:01:22 +0000171static int
Damien Millerf58b58c2003-11-17 21:18:23 +1100172hostfile_check_key(int bits, const Key *key, const char *host, const char *filename, int linenum)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000173{
Damien Miller0bc1bd82000-11-13 22:57:25 +1100174 if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
Damien Miller450a7a12000-03-26 13:04:51 +1000175 return 1;
176 if (bits != BN_num_bits(key->rsa->n)) {
Damien Miller996acd22003-04-09 20:59:48 +1000177 logit("Warning: %s, line %d: keysize mismatch for host %s: "
Damien Miller450a7a12000-03-26 13:04:51 +1000178 "actual %d vs. announced %d.",
179 filename, linenum, host, BN_num_bits(key->rsa->n), bits);
Damien Miller996acd22003-04-09 20:59:48 +1000180 logit("Warning: replace %d with %d in %s, line %d.",
Damien Miller450a7a12000-03-26 13:04:51 +1000181 bits, BN_num_bits(key->rsa->n), filename, linenum);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000182 }
Damien Miller450a7a12000-03-26 13:04:51 +1000183 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000184}
185
Damien Miller5428f641999-11-25 11:54:57 +1100186/*
187 * Checks whether the given host (which must be in all lowercase) is already
188 * in the list of our known hosts. Returns HOST_OK if the host is known and
189 * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
190 * if the host is known but used to have a different host key.
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000191 *
192 * If no 'key' has been specified and a key of type 'keytype' is known
193 * for the specified host, then HOST_FOUND is returned.
Damien Miller5428f641999-11-25 11:54:57 +1100194 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000195
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000196static HostStatus
197check_host_in_hostfile_by_key_or_type(const char *filename,
Damien Millerf58b58c2003-11-17 21:18:23 +1100198 const char *host, const Key *key, int keytype, Key *found, int *numret)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000199{
Damien Miller95def091999-11-25 00:26:21 +1100200 FILE *f;
201 char line[8192];
202 int linenum = 0;
Ben Lindstromab0cedc2001-04-07 17:23:43 +0000203 u_int kbits;
Damien Millere1776152005-03-01 21:47:37 +1100204 char *cp, *cp2, *hashed_host;
Damien Miller95def091999-11-25 00:26:21 +1100205 HostStatus end_return;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000206
Darren Tucker1b118882009-10-24 11:40:32 +1100207 debug3("check_host_in_hostfile: host %s filename %s", host, filename);
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000208
Damien Miller95def091999-11-25 00:26:21 +1100209 /* Open the file containing the list of known hosts. */
210 f = fopen(filename, "r");
211 if (!f)
212 return HOST_NEW;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000213
Damien Miller5428f641999-11-25 11:54:57 +1100214 /*
215 * Return value when the loop terminates. This is set to
216 * HOST_CHANGED if we have seen a different key for the host and have
217 * not found the proper one.
218 */
Damien Miller95def091999-11-25 00:26:21 +1100219 end_return = HOST_NEW;
Damien Miller7e8e8201999-11-16 13:37:16 +1100220
Ben Lindstromab0cedc2001-04-07 17:23:43 +0000221 /* Go through the file. */
Damien Miller95def091999-11-25 00:26:21 +1100222 while (fgets(line, sizeof(line), f)) {
223 cp = line;
224 linenum++;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000225
Damien Miller5428f641999-11-25 11:54:57 +1100226 /* Skip any leading whitespace, comments and empty lines. */
227 for (; *cp == ' ' || *cp == '\t'; cp++)
228 ;
Damien Miller95def091999-11-25 00:26:21 +1100229 if (!*cp || *cp == '#' || *cp == '\n')
230 continue;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000231
Damien Miller95def091999-11-25 00:26:21 +1100232 /* Find the end of the host name portion. */
Damien Miller5428f641999-11-25 11:54:57 +1100233 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
234 ;
Damien Miller7e8e8201999-11-16 13:37:16 +1100235
Damien Miller95def091999-11-25 00:26:21 +1100236 /* Check if the host name matches. */
Damien Millere1776152005-03-01 21:47:37 +1100237 if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) {
238 if (*cp != HASH_DELIM)
239 continue;
240 hashed_host = host_hash(host, cp, (u_int) (cp2 - cp));
241 if (hashed_host == NULL) {
242 debug("Invalid hashed host line %d of %s",
243 linenum, filename);
244 continue;
245 }
246 if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0)
247 continue;
248 }
Damien Miller95def091999-11-25 00:26:21 +1100249
250 /* Got a match. Skip host name. */
251 cp = cp2;
252
Damien Miller5428f641999-11-25 11:54:57 +1100253 /*
254 * Extract the key from the line. This will skip any leading
255 * whitespace. Ignore badly formatted lines.
256 */
Damien Miller450a7a12000-03-26 13:04:51 +1000257 if (!hostfile_read_key(&cp, &kbits, found))
258 continue;
Damien Miller95def091999-11-25 00:26:21 +1100259
Ben Lindstrom46c16222000-12-22 01:43:59 +0000260 if (numret != NULL)
261 *numret = linenum;
262
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000263 if (key == NULL) {
264 /* we found a key of the requested type */
Damien Miller6db780e2006-03-26 13:52:20 +1100265 if (found->type == keytype) {
266 fclose(f);
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000267 return HOST_FOUND;
Damien Miller6db780e2006-03-26 13:52:20 +1100268 }
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000269 continue;
270 }
271
272 if (!hostfile_check_key(kbits, found, host, filename, linenum))
273 continue;
274
Damien Miller95def091999-11-25 00:26:21 +1100275 /* Check if the current key is the same as the given key. */
Damien Miller450a7a12000-03-26 13:04:51 +1000276 if (key_equal(key, found)) {
Damien Miller95def091999-11-25 00:26:21 +1100277 /* Ok, they match. */
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000278 debug3("check_host_in_hostfile: match line %d", linenum);
Damien Miller95def091999-11-25 00:26:21 +1100279 fclose(f);
280 return HOST_OK;
281 }
Damien Miller5428f641999-11-25 11:54:57 +1100282 /*
283 * They do not match. We will continue to go through the
284 * file; however, we note that we will not return that it is
285 * new.
286 */
Damien Miller95def091999-11-25 00:26:21 +1100287 end_return = HOST_CHANGED;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000288 }
Damien Miller95def091999-11-25 00:26:21 +1100289 /* Clear variables and close the file. */
290 fclose(f);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000291
Damien Miller5428f641999-11-25 11:54:57 +1100292 /*
293 * Return either HOST_NEW or HOST_CHANGED, depending on whether we
294 * saw a different key for the host.
295 */
Damien Miller95def091999-11-25 00:26:21 +1100296 return end_return;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000297}
298
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000299HostStatus
Damien Millerf58b58c2003-11-17 21:18:23 +1100300check_host_in_hostfile(const char *filename, const char *host, const Key *key,
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000301 Key *found, int *numret)
302{
303 if (key == NULL)
304 fatal("no key to look up");
305 return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0,
306 found, numret));
307}
308
309int
310lookup_key_in_hostfile_by_type(const char *filename, const char *host,
311 int keytype, Key *found, int *numret)
312{
313 return (check_host_in_hostfile_by_key_or_type(filename, host, NULL,
314 keytype, found, numret) == HOST_FOUND);
315}
316
Damien Miller5428f641999-11-25 11:54:57 +1100317/*
318 * Appends an entry to the host file. Returns false if the entry could not
319 * be appended.
320 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000321
322int
Darren Tucker47eede72005-03-14 23:08:12 +1100323add_host_to_hostfile(const char *filename, const char *host, const Key *key,
Damien Millere1776152005-03-01 21:47:37 +1100324 int store_hash)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000325{
Damien Miller95def091999-11-25 00:26:21 +1100326 FILE *f;
Damien Miller450a7a12000-03-26 13:04:51 +1000327 int success = 0;
Darren Tucker40858532005-08-02 17:07:07 +1000328 char *hashed_host = NULL;
Damien Millere1776152005-03-01 21:47:37 +1100329
Damien Miller450a7a12000-03-26 13:04:51 +1000330 if (key == NULL)
Damien Millereba71ba2000-04-29 23:57:08 +1000331 return 1; /* XXX ? */
Damien Miller95def091999-11-25 00:26:21 +1100332 f = fopen(filename, "a");
333 if (!f)
334 return 0;
Damien Millere1776152005-03-01 21:47:37 +1100335
336 if (store_hash) {
337 if ((hashed_host = host_hash(host, NULL, 0)) == NULL) {
338 error("add_host_to_hostfile: host_hash failed");
339 fclose(f);
340 return 0;
341 }
342 }
343 fprintf(f, "%s ", store_hash ? hashed_host : host);
344
Damien Miller450a7a12000-03-26 13:04:51 +1000345 if (key_write(key, f)) {
Damien Miller450a7a12000-03-26 13:04:51 +1000346 success = 1;
347 } else {
Damien Millereba71ba2000-04-29 23:57:08 +1000348 error("add_host_to_hostfile: saving key in %s failed", filename);
Damien Miller95def091999-11-25 00:26:21 +1100349 }
Damien Millereba71ba2000-04-29 23:57:08 +1000350 fprintf(f, "\n");
Damien Miller95def091999-11-25 00:26:21 +1100351 fclose(f);
Damien Miller450a7a12000-03-26 13:04:51 +1000352 return success;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000353}