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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" | |
bcbf86ec | 39 | RCSID("$OpenBSD: hostfile.c,v 1.20 2000/09/07 20:27:51 deraadt Exp $"); |
4fe2af09 | 40 | |
8efc0c15 | 41 | #include "packet.h" |
4fe2af09 | 42 | #include "match.h" |
8efc0c15 | 43 | #include "ssh.h" |
35484284 | 44 | #include <openssl/rsa.h> |
45 | #include <openssl/dsa.h> | |
4fe2af09 | 46 | #include "key.h" |
47 | #include "hostfile.h" | |
8efc0c15 | 48 | |
aa3378df | 49 | /* |
4fe2af09 | 50 | * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the |
51 | * pointer over the key. Skips any whitespace at the beginning and at end. | |
aa3378df | 52 | */ |
8efc0c15 | 53 | |
54 | int | |
4fe2af09 | 55 | hostfile_read_key(char **cpp, unsigned int *bitsp, Key *ret) |
8efc0c15 | 56 | { |
5260325f | 57 | unsigned int bits; |
58 | char *cp; | |
59 | ||
60 | /* Skip leading whitespace. */ | |
aa3378df | 61 | for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) |
62 | ; | |
5260325f | 63 | |
a306f2dd | 64 | bits = key_read(ret, &cp); |
65 | if (bits == 0) | |
5260325f | 66 | return 0; |
67 | ||
68 | /* Skip trailing whitespace. */ | |
aa3378df | 69 | for (; *cp == ' ' || *cp == '\t'; cp++) |
70 | ; | |
5260325f | 71 | |
72 | /* Return results. */ | |
73 | *cpp = cp; | |
74 | *bitsp = bits; | |
75 | return 1; | |
8efc0c15 | 76 | } |
77 | ||
8efc0c15 | 78 | int |
4fe2af09 | 79 | auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n) |
8efc0c15 | 80 | { |
4fe2af09 | 81 | Key *k = key_new(KEY_RSA); |
82 | int ret = hostfile_read_key(cpp, bitsp, k); | |
83 | BN_copy(e, k->rsa->e); | |
84 | BN_copy(n, k->rsa->n); | |
85 | key_free(k); | |
86 | return ret; | |
87 | } | |
5260325f | 88 | |
4fe2af09 | 89 | int |
90 | hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum) | |
91 | { | |
92 | if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) | |
93 | return 1; | |
94 | if (bits != BN_num_bits(key->rsa->n)) { | |
0b242b12 | 95 | log("Warning: %s, line %d: keysize mismatch for host %s: " |
4fe2af09 | 96 | "actual %d vs. announced %d.", |
97 | filename, linenum, host, BN_num_bits(key->rsa->n), bits); | |
0b242b12 | 98 | log("Warning: replace %d with %d in %s, line %d.", |
4fe2af09 | 99 | bits, BN_num_bits(key->rsa->n), filename, linenum); |
8efc0c15 | 100 | } |
4fe2af09 | 101 | return 1; |
8efc0c15 | 102 | } |
103 | ||
aa3378df | 104 | /* |
105 | * Checks whether the given host (which must be in all lowercase) is already | |
106 | * in the list of our known hosts. Returns HOST_OK if the host is known and | |
107 | * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED | |
108 | * if the host is known but used to have a different host key. | |
109 | */ | |
8efc0c15 | 110 | |
111 | HostStatus | |
4fe2af09 | 112 | check_host_in_hostfile(const char *filename, const char *host, Key *key, Key *found) |
8efc0c15 | 113 | { |
5260325f | 114 | FILE *f; |
115 | char line[8192]; | |
116 | int linenum = 0; | |
c8d54615 | 117 | unsigned int kbits, hostlen; |
5260325f | 118 | char *cp, *cp2; |
119 | HostStatus end_return; | |
120 | ||
4fe2af09 | 121 | if (key == NULL) |
122 | fatal("no key to look up"); | |
5260325f | 123 | /* Open the file containing the list of known hosts. */ |
124 | f = fopen(filename, "r"); | |
125 | if (!f) | |
126 | return HOST_NEW; | |
127 | ||
128 | /* Cache the length of the host name. */ | |
129 | hostlen = strlen(host); | |
130 | ||
aa3378df | 131 | /* |
132 | * Return value when the loop terminates. This is set to | |
133 | * HOST_CHANGED if we have seen a different key for the host and have | |
134 | * not found the proper one. | |
135 | */ | |
5260325f | 136 | end_return = HOST_NEW; |
137 | ||
5260325f | 138 | /* Go trough the file. */ |
139 | while (fgets(line, sizeof(line), f)) { | |
140 | cp = line; | |
141 | linenum++; | |
142 | ||
aa3378df | 143 | /* Skip any leading whitespace, comments and empty lines. */ |
144 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
145 | ; | |
5260325f | 146 | if (!*cp || *cp == '#' || *cp == '\n') |
147 | continue; | |
148 | ||
149 | /* Find the end of the host name portion. */ | |
aa3378df | 150 | for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) |
151 | ; | |
5260325f | 152 | |
153 | /* Check if the host name matches. */ | |
fa649821 | 154 | if (match_hostname(host, cp, (unsigned int) (cp2 - cp)) != 1) |
5260325f | 155 | continue; |
156 | ||
157 | /* Got a match. Skip host name. */ | |
158 | cp = cp2; | |
159 | ||
aa3378df | 160 | /* |
161 | * Extract the key from the line. This will skip any leading | |
162 | * whitespace. Ignore badly formatted lines. | |
163 | */ | |
4fe2af09 | 164 | if (!hostfile_read_key(&cp, &kbits, found)) |
165 | continue; | |
166 | if (!hostfile_check_key(kbits, found, host, filename, linenum)) | |
5260325f | 167 | continue; |
168 | ||
5260325f | 169 | /* Check if the current key is the same as the given key. */ |
4fe2af09 | 170 | if (key_equal(key, found)) { |
5260325f | 171 | /* Ok, they match. */ |
172 | fclose(f); | |
173 | return HOST_OK; | |
174 | } | |
aa3378df | 175 | /* |
176 | * They do not match. We will continue to go through the | |
177 | * file; however, we note that we will not return that it is | |
178 | * new. | |
179 | */ | |
5260325f | 180 | end_return = HOST_CHANGED; |
8efc0c15 | 181 | } |
5260325f | 182 | /* Clear variables and close the file. */ |
183 | fclose(f); | |
184 | ||
aa3378df | 185 | /* |
186 | * Return either HOST_NEW or HOST_CHANGED, depending on whether we | |
187 | * saw a different key for the host. | |
188 | */ | |
5260325f | 189 | return end_return; |
8efc0c15 | 190 | } |
191 | ||
aa3378df | 192 | /* |
193 | * Appends an entry to the host file. Returns false if the entry could not | |
194 | * be appended. | |
195 | */ | |
8efc0c15 | 196 | |
197 | int | |
4fe2af09 | 198 | add_host_to_hostfile(const char *filename, const char *host, Key *key) |
8efc0c15 | 199 | { |
5260325f | 200 | FILE *f; |
4fe2af09 | 201 | int success = 0; |
4fe2af09 | 202 | if (key == NULL) |
a306f2dd | 203 | return 1; /* XXX ? */ |
5260325f | 204 | f = fopen(filename, "a"); |
205 | if (!f) | |
206 | return 0; | |
4fe2af09 | 207 | fprintf(f, "%s ", host); |
208 | if (key_write(key, f)) { | |
4fe2af09 | 209 | success = 1; |
210 | } else { | |
a306f2dd | 211 | error("add_host_to_hostfile: saving key in %s failed", filename); |
5260325f | 212 | } |
a306f2dd | 213 | fprintf(f, "\n"); |
5260325f | 214 | fclose(f); |
4fe2af09 | 215 | return success; |
8efc0c15 | 216 | } |