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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller4af51302000-04-16 11:18:38 +10002 *
Damien Miller95def091999-11-25 00:26:21 +11003 * hostfile.c
Damien Miller4af51302000-04-16 11:18:38 +10004 *
Damien Miller95def091999-11-25 00:26:21 +11005 * Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller4af51302000-04-16 11:18:38 +10006 *
Damien Miller95def091999-11-25 00:26:21 +11007 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 * All rights reserved
Damien Miller4af51302000-04-16 11:18:38 +10009 *
Damien Miller95def091999-11-25 00:26:21 +110010 * Created: Thu Jun 29 07:10:56 1995 ylo
Damien Miller4af51302000-04-16 11:18:38 +100011 *
Damien Miller95def091999-11-25 00:26:21 +110012 * Functions for manipulating the known hosts files.
Damien Miller4af51302000-04-16 11:18:38 +100013 *
Damien Miller95def091999-11-25 00:26:21 +110014 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100015
16#include "includes.h"
Damien Miller4af51302000-04-16 11:18:38 +100017RCSID("$OpenBSD: hostfile.c,v 1.16 2000/04/14 10:30:31 markus Exp $");
Damien Miller450a7a12000-03-26 13:04:51 +100018
19#ifdef HAVE_OPENSSL
20#include <openssl/bn.h>
21#include <openssl/rsa.h>
22#include <openssl/dsa.h>
23#endif
24#ifdef HAVE_SSL
25#include <ssl/bn.h>
26#include <ssl/rsa.h>
27#include <ssl/dsa.h>
28#endif
Damien Millerd4a8b7e1999-10-27 13:42:43 +100029
30#include "packet.h"
Damien Miller450a7a12000-03-26 13:04:51 +100031#include "match.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100032#include "ssh.h"
Damien Miller450a7a12000-03-26 13:04:51 +100033#include "key.h"
34#include "hostfile.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100035
Damien Miller5428f641999-11-25 11:54:57 +110036/*
Damien Miller450a7a12000-03-26 13:04:51 +100037 * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
38 * pointer over the key. Skips any whitespace at the beginning and at end.
Damien Miller5428f641999-11-25 11:54:57 +110039 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100040
41int
Damien Miller450a7a12000-03-26 13:04:51 +100042hostfile_read_key(char **cpp, unsigned int *bitsp, Key *ret)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100043{
Damien Miller95def091999-11-25 00:26:21 +110044 unsigned int bits;
45 char *cp;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100046
Damien Miller95def091999-11-25 00:26:21 +110047 /* Skip leading whitespace. */
Damien Miller5428f641999-11-25 11:54:57 +110048 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
49 ;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100050
Damien Miller95def091999-11-25 00:26:21 +110051 /* Get number of bits. */
52 if (*cp < '0' || *cp > '9')
53 return 0; /* Bad bit count... */
54 for (bits = 0; *cp >= '0' && *cp <= '9'; cp++)
55 bits = 10 * bits + *cp - '0';
Damien Millerd4a8b7e1999-10-27 13:42:43 +100056
Damien Miller450a7a12000-03-26 13:04:51 +100057 if (!key_read(ret, bits, &cp))
Damien Miller95def091999-11-25 00:26:21 +110058 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100059
Damien Miller95def091999-11-25 00:26:21 +110060 /* Skip trailing whitespace. */
Damien Miller5428f641999-11-25 11:54:57 +110061 for (; *cp == ' ' || *cp == '\t'; cp++)
62 ;
Damien Miller95def091999-11-25 00:26:21 +110063
64 /* Return results. */
65 *cpp = cp;
66 *bitsp = bits;
67 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100068}
69
Damien Miller450a7a12000-03-26 13:04:51 +100070int
71auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n)
72{
73 Key *k = key_new(KEY_RSA);
74 int ret = hostfile_read_key(cpp, bitsp, k);
75 BN_copy(e, k->rsa->e);
76 BN_copy(n, k->rsa->n);
77 key_free(k);
78 return ret;
79}
Damien Millerd4a8b7e1999-10-27 13:42:43 +100080
81int
Damien Miller450a7a12000-03-26 13:04:51 +100082hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100083{
Damien Miller450a7a12000-03-26 13:04:51 +100084 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL)
85 return 1;
86 if (bits != BN_num_bits(key->rsa->n)) {
87 error("Warning: %s, line %d: keysize mismatch for host %s: "
88 "actual %d vs. announced %d.",
89 filename, linenum, host, BN_num_bits(key->rsa->n), bits);
90 error("Warning: replace %d with %d in %s, line %d.",
91 bits, BN_num_bits(key->rsa->n), filename, linenum);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100092 }
Damien Miller450a7a12000-03-26 13:04:51 +100093 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100094}
95
Damien Miller5428f641999-11-25 11:54:57 +110096/*
97 * Checks whether the given host (which must be in all lowercase) is already
98 * in the list of our known hosts. Returns HOST_OK if the host is known and
99 * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
100 * if the host is known but used to have a different host key.
101 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000102
103HostStatus
Damien Miller450a7a12000-03-26 13:04:51 +1000104check_host_in_hostfile(const char *filename, const char *host, Key *key, Key *found)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000105{
Damien Miller95def091999-11-25 00:26:21 +1100106 FILE *f;
107 char line[8192];
108 int linenum = 0;
Damien Miller98c7ad62000-03-09 21:27:49 +1100109 unsigned int kbits, hostlen;
Damien Miller95def091999-11-25 00:26:21 +1100110 char *cp, *cp2;
111 HostStatus end_return;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000112
Damien Miller450a7a12000-03-26 13:04:51 +1000113 if (key == NULL)
114 fatal("no key to look up");
Damien Miller95def091999-11-25 00:26:21 +1100115 /* Open the file containing the list of known hosts. */
116 f = fopen(filename, "r");
117 if (!f)
118 return HOST_NEW;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000119
Damien Miller95def091999-11-25 00:26:21 +1100120 /* Cache the length of the host name. */
121 hostlen = strlen(host);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000122
Damien Miller5428f641999-11-25 11:54:57 +1100123 /*
124 * Return value when the loop terminates. This is set to
125 * HOST_CHANGED if we have seen a different key for the host and have
126 * not found the proper one.
127 */
Damien Miller95def091999-11-25 00:26:21 +1100128 end_return = HOST_NEW;
Damien Miller7e8e8201999-11-16 13:37:16 +1100129
Damien Miller95def091999-11-25 00:26:21 +1100130 /* Go trough the file. */
131 while (fgets(line, sizeof(line), f)) {
132 cp = line;
133 linenum++;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000134
Damien Miller5428f641999-11-25 11:54:57 +1100135 /* Skip any leading whitespace, comments and empty lines. */
136 for (; *cp == ' ' || *cp == '\t'; cp++)
137 ;
Damien Miller95def091999-11-25 00:26:21 +1100138 if (!*cp || *cp == '#' || *cp == '\n')
139 continue;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000140
Damien Miller95def091999-11-25 00:26:21 +1100141 /* Find the end of the host name portion. */
Damien Miller5428f641999-11-25 11:54:57 +1100142 for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
143 ;
Damien Miller7e8e8201999-11-16 13:37:16 +1100144
Damien Miller95def091999-11-25 00:26:21 +1100145 /* Check if the host name matches. */
146 if (!match_hostname(host, cp, (unsigned int) (cp2 - cp)))
147 continue;
148
149 /* Got a match. Skip host name. */
150 cp = cp2;
151
Damien Miller5428f641999-11-25 11:54:57 +1100152 /*
153 * Extract the key from the line. This will skip any leading
154 * whitespace. Ignore badly formatted lines.
155 */
Damien Miller450a7a12000-03-26 13:04:51 +1000156 if (!hostfile_read_key(&cp, &kbits, found))
157 continue;
158 if (!hostfile_check_key(kbits, found, host, filename, linenum))
Damien Miller95def091999-11-25 00:26:21 +1100159 continue;
160
Damien Miller95def091999-11-25 00:26:21 +1100161 /* Check if the current key is the same as the given key. */
Damien Miller450a7a12000-03-26 13:04:51 +1000162 if (key_equal(key, found)) {
Damien Miller95def091999-11-25 00:26:21 +1100163 /* Ok, they match. */
164 fclose(f);
165 return HOST_OK;
166 }
Damien Miller5428f641999-11-25 11:54:57 +1100167 /*
168 * They do not match. We will continue to go through the
169 * file; however, we note that we will not return that it is
170 * new.
171 */
Damien Miller95def091999-11-25 00:26:21 +1100172 end_return = HOST_CHANGED;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000173 }
Damien Miller95def091999-11-25 00:26:21 +1100174 /* Clear variables and close the file. */
175 fclose(f);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000176
Damien Miller5428f641999-11-25 11:54:57 +1100177 /*
178 * Return either HOST_NEW or HOST_CHANGED, depending on whether we
179 * saw a different key for the host.
180 */
Damien Miller95def091999-11-25 00:26:21 +1100181 return end_return;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000182}
183
Damien Miller5428f641999-11-25 11:54:57 +1100184/*
185 * Appends an entry to the host file. Returns false if the entry could not
186 * be appended.
187 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000188
189int
Damien Miller450a7a12000-03-26 13:04:51 +1000190add_host_to_hostfile(const char *filename, const char *host, Key *key)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000191{
Damien Miller95def091999-11-25 00:26:21 +1100192 FILE *f;
Damien Miller450a7a12000-03-26 13:04:51 +1000193 int success = 0;
194
195 if (key == NULL)
196 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000197
Damien Miller95def091999-11-25 00:26:21 +1100198 /* Open the file for appending. */
199 f = fopen(filename, "a");
200 if (!f)
201 return 0;
Damien Miller7e8e8201999-11-16 13:37:16 +1100202
Damien Miller450a7a12000-03-26 13:04:51 +1000203 fprintf(f, "%s ", host);
204 if (key_write(key, f)) {
205 fprintf(f, "\n");
206 success = 1;
207 } else {
208 error("add_host_to_hostfile: saving key failed");
Damien Miller95def091999-11-25 00:26:21 +1100209 }
Damien Miller95def091999-11-25 00:26:21 +1100210
211 /* Close the file. */
212 fclose(f);
Damien Miller450a7a12000-03-26 13:04:51 +1000213 return success;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000214}