]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Functions for manipulating the known hosts files. | |
6 | * | |
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". | |
12 | * | |
13 | * | |
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. | |
36 | */ | |
37 | ||
38 | #include "includes.h" | |
39 | RCSID("$OpenBSD: hostfile.c,v 1.20 2000/09/07 20:27:51 deraadt Exp $"); | |
40 | ||
41 | #include "packet.h" | |
42 | #include "match.h" | |
43 | #include "ssh.h" | |
44 | #include <openssl/rsa.h> | |
45 | #include <openssl/dsa.h> | |
46 | #include "key.h" | |
47 | #include "hostfile.h" | |
48 | ||
49 | /* | |
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. | |
52 | */ | |
53 | ||
54 | int | |
55 | hostfile_read_key(char **cpp, unsigned int *bitsp, Key *ret) | |
56 | { | |
57 | unsigned int bits; | |
58 | char *cp; | |
59 | ||
60 | /* Skip leading whitespace. */ | |
61 | for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) | |
62 | ; | |
63 | ||
64 | bits = key_read(ret, &cp); | |
65 | if (bits == 0) | |
66 | return 0; | |
67 | ||
68 | /* Skip trailing whitespace. */ | |
69 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
70 | ; | |
71 | ||
72 | /* Return results. */ | |
73 | *cpp = cp; | |
74 | *bitsp = bits; | |
75 | return 1; | |
76 | } | |
77 | ||
78 | int | |
79 | auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n) | |
80 | { | |
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 | } | |
88 | ||
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)) { | |
95 | log("Warning: %s, line %d: keysize mismatch for host %s: " | |
96 | "actual %d vs. announced %d.", | |
97 | filename, linenum, host, BN_num_bits(key->rsa->n), bits); | |
98 | log("Warning: replace %d with %d in %s, line %d.", | |
99 | bits, BN_num_bits(key->rsa->n), filename, linenum); | |
100 | } | |
101 | return 1; | |
102 | } | |
103 | ||
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 | */ | |
110 | ||
111 | HostStatus | |
112 | check_host_in_hostfile(const char *filename, const char *host, Key *key, Key *found) | |
113 | { | |
114 | FILE *f; | |
115 | char line[8192]; | |
116 | int linenum = 0; | |
117 | unsigned int kbits, hostlen; | |
118 | char *cp, *cp2; | |
119 | HostStatus end_return; | |
120 | ||
121 | if (key == NULL) | |
122 | fatal("no key to look up"); | |
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 | ||
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 | */ | |
136 | end_return = HOST_NEW; | |
137 | ||
138 | /* Go trough the file. */ | |
139 | while (fgets(line, sizeof(line), f)) { | |
140 | cp = line; | |
141 | linenum++; | |
142 | ||
143 | /* Skip any leading whitespace, comments and empty lines. */ | |
144 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
145 | ; | |
146 | if (!*cp || *cp == '#' || *cp == '\n') | |
147 | continue; | |
148 | ||
149 | /* Find the end of the host name portion. */ | |
150 | for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) | |
151 | ; | |
152 | ||
153 | /* Check if the host name matches. */ | |
154 | if (match_hostname(host, cp, (unsigned int) (cp2 - cp)) != 1) | |
155 | continue; | |
156 | ||
157 | /* Got a match. Skip host name. */ | |
158 | cp = cp2; | |
159 | ||
160 | /* | |
161 | * Extract the key from the line. This will skip any leading | |
162 | * whitespace. Ignore badly formatted lines. | |
163 | */ | |
164 | if (!hostfile_read_key(&cp, &kbits, found)) | |
165 | continue; | |
166 | if (!hostfile_check_key(kbits, found, host, filename, linenum)) | |
167 | continue; | |
168 | ||
169 | /* Check if the current key is the same as the given key. */ | |
170 | if (key_equal(key, found)) { | |
171 | /* Ok, they match. */ | |
172 | fclose(f); | |
173 | return HOST_OK; | |
174 | } | |
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 | */ | |
180 | end_return = HOST_CHANGED; | |
181 | } | |
182 | /* Clear variables and close the file. */ | |
183 | fclose(f); | |
184 | ||
185 | /* | |
186 | * Return either HOST_NEW or HOST_CHANGED, depending on whether we | |
187 | * saw a different key for the host. | |
188 | */ | |
189 | return end_return; | |
190 | } | |
191 | ||
192 | /* | |
193 | * Appends an entry to the host file. Returns false if the entry could not | |
194 | * be appended. | |
195 | */ | |
196 | ||
197 | int | |
198 | add_host_to_hostfile(const char *filename, const char *host, Key *key) | |
199 | { | |
200 | FILE *f; | |
201 | int success = 0; | |
202 | if (key == NULL) | |
203 | return 1; /* XXX ? */ | |
204 | f = fopen(filename, "a"); | |
205 | if (!f) | |
206 | return 0; | |
207 | fprintf(f, "%s ", host); | |
208 | if (key_write(key, f)) { | |
209 | success = 1; | |
210 | } else { | |
211 | error("add_host_to_hostfile: saving key in %s failed", filename); | |
212 | } | |
213 | fprintf(f, "\n"); | |
214 | fclose(f); | |
215 | return success; | |
216 | } |