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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller95def091999-11-25 00:26:21 +11003 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11005 * Functions for manipulating the known hosts files.
Damien Miller4af51302000-04-16 11:18:38 +10006 *
Damien Millere4340be2000-09-16 13:29:08 +11007 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 *
13 *
Ben Lindstrom44697232001-07-04 03:32:30 +000014 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
Damien Millere4340be2000-09-16 13:29:08 +110015 * Copyright (c) 1999 Niels Provos. All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Damien Miller95def091999-11-25 00:26:21 +110036 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100037
38#include "includes.h"
Ben Lindstrom44697232001-07-04 03:32:30 +000039RCSID("$OpenBSD: hostfile.c,v 1.28 2001/06/25 08:25:37 markus Exp $");
Damien Miller450a7a12000-03-26 13:04:51 +100040
Damien Millerd4a8b7e1999-10-27 13:42:43 +100041#include "packet.h"
Damien Miller450a7a12000-03-26 13:04:51 +100042#include "match.h"
Damien Miller450a7a12000-03-26 13:04:51 +100043#include "key.h"
44#include "hostfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000045#include "log.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100046
Damien Miller5428f641999-11-25 11:54:57 +110047/*
Damien Miller450a7a12000-03-26 13:04:51 +100048 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
49 * pointer over the key. Skips any whitespace at the beginning and at end.
Damien Miller5428f641999-11-25 11:54:57 +110050 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100051
Ben Lindstrombba81212001-06-25 05:01:22 +000052static int
Ben Lindstrom46c16222000-12-22 01:43:59 +000053hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100054{
Damien Miller95def091999-11-25 00:26:21 +110055 char *cp;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100056
Damien Miller95def091999-11-25 00:26:21 +110057 /* Skip leading whitespace. */
Damien Miller5428f641999-11-25 11:54:57 +110058 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
59 ;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100060
Damien Miller0bc1bd82000-11-13 22:57:25 +110061 if (key_read(ret, &cp) != 1)
Damien Miller95def091999-11-25 00:26:21 +110062 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100063
Damien Miller95def091999-11-25 00:26:21 +110064 /* Skip trailing whitespace. */
Damien Miller5428f641999-11-25 11:54:57 +110065 for (; *cp == ' ' || *cp == '\t'; cp++)
66 ;
Damien Miller95def091999-11-25 00:26:21 +110067
68 /* Return results. */
69 *cpp = cp;
Damien Miller0bc1bd82000-11-13 22:57:25 +110070 *bitsp = key_size(ret);
Damien Miller95def091999-11-25 00:26:21 +110071 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100072}
73
Damien Miller450a7a12000-03-26 13:04:51 +100074int
Ben Lindstrom46c16222000-12-22 01:43:59 +000075auth_rsa_read_key(char **cpp, u_int *bitsp, BIGNUM * e, BIGNUM * n)
Damien Miller450a7a12000-03-26 13:04:51 +100076{
Damien Miller0bc1bd82000-11-13 22:57:25 +110077 Key *k = key_new(KEY_RSA1);
Damien Miller450a7a12000-03-26 13:04:51 +100078 int ret = hostfile_read_key(cpp, bitsp, k);
79 BN_copy(e, k->rsa->e);
80 BN_copy(n, k->rsa->n);
81 key_free(k);
82 return ret;
83}
Damien Millerd4a8b7e1999-10-27 13:42:43 +100084
Ben Lindstrombba81212001-06-25 05:01:22 +000085static int
Damien Miller450a7a12000-03-26 13:04:51 +100086hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100087{
Damien Miller0bc1bd82000-11-13 22:57:25 +110088 if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
Damien Miller450a7a12000-03-26 13:04:51 +100089 return 1;
90 if (bits != BN_num_bits(key->rsa->n)) {
Damien Millerbd483e72000-04-30 10:00:53 +100091 log("Warning: %s, line %d: keysize mismatch for host %s: "
Damien Miller450a7a12000-03-26 13:04:51 +100092 "actual %d vs. announced %d.",
93 filename, linenum, host, BN_num_bits(key->rsa->n), bits);
Damien Millerbd483e72000-04-30 10:00:53 +100094 log("Warning: replace %d with %d in %s, line %d.",
Damien Miller450a7a12000-03-26 13:04:51 +100095 bits, BN_num_bits(key->rsa->n), filename, linenum);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100096 }
Damien Miller450a7a12000-03-26 13:04:51 +100097 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100098}
99
Damien Miller5428f641999-11-25 11:54:57 +1100100/*
101 * Checks whether the given host (which must be in all lowercase) is already
102 * in the list of our known hosts. Returns HOST_OK if the host is known and
103 * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
104 * if the host is known but used to have a different host key.
105 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000106
107HostStatus
Ben Lindstrom46c16222000-12-22 01:43:59 +0000108check_host_in_hostfile(const char *filename, const char *host, Key *key,
109 Key *found, int *numret)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000110{
Damien Miller95def091999-11-25 00:26:21 +1100111 FILE *f;
112 char line[8192];
113 int linenum = 0;
Ben Lindstromab0cedc2001-04-07 17:23:43 +0000114 u_int kbits;
Damien Miller95def091999-11-25 00:26:21 +1100115 char *cp, *cp2;
116 HostStatus end_return;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000117
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000118 debug3("check_host_in_hostfile: filename %s", filename);
Damien Miller450a7a12000-03-26 13:04:51 +1000119 if (key == NULL)
120 fatal("no key to look up");
Damien Miller95def091999-11-25 00:26:21 +1100121 /* Open the file containing the list of known hosts. */
122 f = fopen(filename, "r");
123 if (!f)
124 return HOST_NEW;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000125
Damien Miller5428f641999-11-25 11:54:57 +1100126 /*
127 * Return value when the loop terminates. This is set to
128 * HOST_CHANGED if we have seen a different key for the host and have
129 * not found the proper one.
130 */
Damien Miller95def091999-11-25 00:26:21 +1100131 end_return = HOST_NEW;
Damien Miller7e8e8201999-11-16 13:37:16 +1100132
Ben Lindstromab0cedc2001-04-07 17:23:43 +0000133 /* Go through the file. */
Damien Miller95def091999-11-25 00:26:21 +1100134 while (fgets(line, sizeof(line), f)) {
135 cp = line;
136 linenum++;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000137
Damien Miller5428f641999-11-25 11:54:57 +1100138 /* Skip any leading whitespace, comments and empty lines. */
139 for (; *cp == ' ' || *cp == '\t'; cp++)
140 ;
Damien Miller95def091999-11-25 00:26:21 +1100141 if (!*cp || *cp == '#' || *cp == '\n')
142 continue;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000143
Damien Miller95def091999-11-25 00:26:21 +1100144 /* Find the end of the host name portion. */
Damien Miller5428f641999-11-25 11:54:57 +1100145 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
146 ;
Damien Miller7e8e8201999-11-16 13:37:16 +1100147
Damien Miller95def091999-11-25 00:26:21 +1100148 /* Check if the host name matches. */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000149 if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1)
Damien Miller95def091999-11-25 00:26:21 +1100150 continue;
151
152 /* Got a match. Skip host name. */
153 cp = cp2;
154
Damien Miller5428f641999-11-25 11:54:57 +1100155 /*
156 * Extract the key from the line. This will skip any leading
157 * whitespace. Ignore badly formatted lines.
158 */
Damien Miller450a7a12000-03-26 13:04:51 +1000159 if (!hostfile_read_key(&cp, &kbits, found))
160 continue;
161 if (!hostfile_check_key(kbits, found, host, filename, linenum))
Damien Miller95def091999-11-25 00:26:21 +1100162 continue;
163
Ben Lindstrom46c16222000-12-22 01:43:59 +0000164 if (numret != NULL)
165 *numret = linenum;
166
Damien Miller95def091999-11-25 00:26:21 +1100167 /* Check if the current key is the same as the given key. */
Damien Miller450a7a12000-03-26 13:04:51 +1000168 if (key_equal(key, found)) {
Damien Miller95def091999-11-25 00:26:21 +1100169 /* Ok, they match. */
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000170 debug3("check_host_in_hostfile: match line %d", linenum);
Damien Miller95def091999-11-25 00:26:21 +1100171 fclose(f);
172 return HOST_OK;
173 }
Damien Miller5428f641999-11-25 11:54:57 +1100174 /*
175 * They do not match. We will continue to go through the
176 * file; however, we note that we will not return that it is
177 * new.
178 */
Damien Miller95def091999-11-25 00:26:21 +1100179 end_return = HOST_CHANGED;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000180 }
Damien Miller95def091999-11-25 00:26:21 +1100181 /* Clear variables and close the file. */
182 fclose(f);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000183
Damien Miller5428f641999-11-25 11:54:57 +1100184 /*
185 * Return either HOST_NEW or HOST_CHANGED, depending on whether we
186 * saw a different key for the host.
187 */
Damien Miller95def091999-11-25 00:26:21 +1100188 return end_return;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000189}
190
Damien Miller5428f641999-11-25 11:54:57 +1100191/*
192 * Appends an entry to the host file. Returns false if the entry could not
193 * be appended.
194 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000195
196int
Damien Miller450a7a12000-03-26 13:04:51 +1000197add_host_to_hostfile(const char *filename, const char *host, Key *key)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000198{
Damien Miller95def091999-11-25 00:26:21 +1100199 FILE *f;
Damien Miller450a7a12000-03-26 13:04:51 +1000200 int success = 0;
Damien Miller450a7a12000-03-26 13:04:51 +1000201 if (key == NULL)
Damien Millereba71ba2000-04-29 23:57:08 +1000202 return 1; /* XXX ? */
Damien Miller95def091999-11-25 00:26:21 +1100203 f = fopen(filename, "a");
204 if (!f)
205 return 0;
Damien Miller450a7a12000-03-26 13:04:51 +1000206 fprintf(f, "%s ", host);
207 if (key_write(key, f)) {
Damien Miller450a7a12000-03-26 13:04:51 +1000208 success = 1;
209 } else {
Damien Millereba71ba2000-04-29 23:57:08 +1000210 error("add_host_to_hostfile: saving key in %s failed", filename);
Damien Miller95def091999-11-25 00:26:21 +1100211 }
Damien Millereba71ba2000-04-29 23:57:08 +1000212 fprintf(f, "\n");
Damien Miller95def091999-11-25 00:26:21 +1100213 fclose(f);
Damien Miller450a7a12000-03-26 13:04:51 +1000214 return success;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000215}