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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
4 | * All rights reserved | |
bcbf86ec | 5 | * Functions for manipulating the known hosts files. |
6ae2364d | 6 | * |
bcbf86ec | 7 | * 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". | |
6ae2364d | 12 | * |
6ae2364d | 13 | * |
bcbf86ec | 14 | * Copyright (c) 1999,2000 Markus Friedl. All rights reserved. |
15 | * 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. | |
5260325f | 36 | */ |
8efc0c15 | 37 | |
38 | #include "includes.h" | |
d9d49fdb | 39 | RCSID("$OpenBSD: hostfile.c,v 1.25 2001/04/06 22:12:47 stevesk Exp $"); |
4fe2af09 | 40 | |
8efc0c15 | 41 | #include "packet.h" |
4fe2af09 | 42 | #include "match.h" |
4fe2af09 | 43 | #include "key.h" |
44 | #include "hostfile.h" | |
42f11eb2 | 45 | #include "log.h" |
8efc0c15 | 46 | |
aa3378df | 47 | /* |
4fe2af09 | 48 | * 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. | |
aa3378df | 50 | */ |
8efc0c15 | 51 | |
52 | int | |
1e3b8b07 | 53 | hostfile_read_key(char **cpp, u_int *bitsp, Key *ret) |
8efc0c15 | 54 | { |
5260325f | 55 | char *cp; |
56 | ||
57 | /* Skip leading whitespace. */ | |
aa3378df | 58 | for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) |
59 | ; | |
5260325f | 60 | |
fa08c86b | 61 | if (key_read(ret, &cp) != 1) |
5260325f | 62 | return 0; |
63 | ||
64 | /* Skip trailing whitespace. */ | |
aa3378df | 65 | for (; *cp == ' ' || *cp == '\t'; cp++) |
66 | ; | |
5260325f | 67 | |
68 | /* Return results. */ | |
69 | *cpp = cp; | |
fa08c86b | 70 | *bitsp = key_size(ret); |
5260325f | 71 | return 1; |
8efc0c15 | 72 | } |
73 | ||
8efc0c15 | 74 | int |
1e3b8b07 | 75 | auth_rsa_read_key(char **cpp, u_int *bitsp, BIGNUM * e, BIGNUM * n) |
8efc0c15 | 76 | { |
fa08c86b | 77 | Key *k = key_new(KEY_RSA1); |
4fe2af09 | 78 | 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 | } | |
5260325f | 84 | |
4fe2af09 | 85 | int |
86 | hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum) | |
87 | { | |
fa08c86b | 88 | if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL) |
4fe2af09 | 89 | return 1; |
90 | if (bits != BN_num_bits(key->rsa->n)) { | |
0b242b12 | 91 | log("Warning: %s, line %d: keysize mismatch for host %s: " |
4fe2af09 | 92 | "actual %d vs. announced %d.", |
93 | filename, linenum, host, BN_num_bits(key->rsa->n), bits); | |
0b242b12 | 94 | log("Warning: replace %d with %d in %s, line %d.", |
4fe2af09 | 95 | bits, BN_num_bits(key->rsa->n), filename, linenum); |
8efc0c15 | 96 | } |
4fe2af09 | 97 | return 1; |
8efc0c15 | 98 | } |
99 | ||
aa3378df | 100 | /* |
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 | */ | |
8efc0c15 | 106 | |
107 | HostStatus | |
1e3b8b07 | 108 | check_host_in_hostfile(const char *filename, const char *host, Key *key, |
109 | Key *found, int *numret) | |
8efc0c15 | 110 | { |
5260325f | 111 | FILE *f; |
112 | char line[8192]; | |
113 | int linenum = 0; | |
d9d49fdb | 114 | u_int kbits; |
5260325f | 115 | char *cp, *cp2; |
116 | HostStatus end_return; | |
117 | ||
4fe2af09 | 118 | if (key == NULL) |
119 | fatal("no key to look up"); | |
5260325f | 120 | /* Open the file containing the list of known hosts. */ |
121 | f = fopen(filename, "r"); | |
122 | if (!f) | |
123 | return HOST_NEW; | |
124 | ||
aa3378df | 125 | /* |
126 | * Return value when the loop terminates. This is set to | |
127 | * HOST_CHANGED if we have seen a different key for the host and have | |
128 | * not found the proper one. | |
129 | */ | |
5260325f | 130 | end_return = HOST_NEW; |
131 | ||
d9d49fdb | 132 | /* Go through the file. */ |
5260325f | 133 | while (fgets(line, sizeof(line), f)) { |
134 | cp = line; | |
135 | linenum++; | |
136 | ||
aa3378df | 137 | /* Skip any leading whitespace, comments and empty lines. */ |
138 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
139 | ; | |
5260325f | 140 | if (!*cp || *cp == '#' || *cp == '\n') |
141 | continue; | |
142 | ||
143 | /* Find the end of the host name portion. */ | |
aa3378df | 144 | for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) |
145 | ; | |
5260325f | 146 | |
147 | /* Check if the host name matches. */ | |
1e3b8b07 | 148 | if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) |
5260325f | 149 | continue; |
150 | ||
151 | /* Got a match. Skip host name. */ | |
152 | cp = cp2; | |
153 | ||
aa3378df | 154 | /* |
155 | * Extract the key from the line. This will skip any leading | |
156 | * whitespace. Ignore badly formatted lines. | |
157 | */ | |
4fe2af09 | 158 | if (!hostfile_read_key(&cp, &kbits, found)) |
159 | continue; | |
160 | if (!hostfile_check_key(kbits, found, host, filename, linenum)) | |
5260325f | 161 | continue; |
162 | ||
1e3b8b07 | 163 | if (numret != NULL) |
164 | *numret = linenum; | |
165 | ||
5260325f | 166 | /* Check if the current key is the same as the given key. */ |
4fe2af09 | 167 | if (key_equal(key, found)) { |
5260325f | 168 | /* Ok, they match. */ |
169 | fclose(f); | |
170 | return HOST_OK; | |
171 | } | |
aa3378df | 172 | /* |
173 | * They do not match. We will continue to go through the | |
174 | * file; however, we note that we will not return that it is | |
175 | * new. | |
176 | */ | |
5260325f | 177 | end_return = HOST_CHANGED; |
8efc0c15 | 178 | } |
5260325f | 179 | /* Clear variables and close the file. */ |
180 | fclose(f); | |
181 | ||
aa3378df | 182 | /* |
183 | * Return either HOST_NEW or HOST_CHANGED, depending on whether we | |
184 | * saw a different key for the host. | |
185 | */ | |
5260325f | 186 | return end_return; |
8efc0c15 | 187 | } |
188 | ||
aa3378df | 189 | /* |
190 | * Appends an entry to the host file. Returns false if the entry could not | |
191 | * be appended. | |
192 | */ | |
8efc0c15 | 193 | |
194 | int | |
4fe2af09 | 195 | add_host_to_hostfile(const char *filename, const char *host, Key *key) |
8efc0c15 | 196 | { |
5260325f | 197 | FILE *f; |
4fe2af09 | 198 | int success = 0; |
4fe2af09 | 199 | if (key == NULL) |
a306f2dd | 200 | return 1; /* XXX ? */ |
5260325f | 201 | f = fopen(filename, "a"); |
202 | if (!f) | |
203 | return 0; | |
4fe2af09 | 204 | fprintf(f, "%s ", host); |
205 | if (key_write(key, f)) { | |
4fe2af09 | 206 | success = 1; |
207 | } else { | |
a306f2dd | 208 | error("add_host_to_hostfile: saving key in %s failed", filename); |
5260325f | 209 | } |
a306f2dd | 210 | fprintf(f, "\n"); |
5260325f | 211 | fclose(f); |
4fe2af09 | 212 | return success; |
8efc0c15 | 213 | } |