1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
/*
*
* hostfile.c
*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* Created: Thu Jun 29 07:10:56 1995 ylo
*
* Functions for manipulating the known hosts files.
*
*/
#include "includes.h"
RCSID("$OpenBSD: hostfile.c,v 1.18 2000/04/29 18:11:52 markus Exp $");
#include "packet.h"
#include "match.h"
#include "ssh.h"
#include <openssl/rsa.h>
#include <openssl/dsa.h>
#include "key.h"
#include "hostfile.h"
/*
* Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
* pointer over the key. Skips any whitespace at the beginning and at end.
*/
int
hostfile_read_key(char **cpp, unsigned int *bitsp, Key *ret)
{
unsigned int bits;
char *cp;
/* Skip leading whitespace. */
for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
;
bits = key_read(ret, &cp);
if (bits == 0)
return 0;
/* Skip trailing whitespace. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
/* Return results. */
*cpp = cp;
*bitsp = bits;
return 1;
}
int
auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n)
{
Key *k = key_new(KEY_RSA);
int ret = hostfile_read_key(cpp, bitsp, k);
BN_copy(e, k->rsa->e);
BN_copy(n, k->rsa->n);
key_free(k);
return ret;
}
int
hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
{
if (key == NULL || key->type != KEY_RSA || key->rsa == NULL)
return 1;
if (bits != BN_num_bits(key->rsa->n)) {
log("Warning: %s, line %d: keysize mismatch for host %s: "
"actual %d vs. announced %d.",
filename, linenum, host, BN_num_bits(key->rsa->n), bits);
log("Warning: replace %d with %d in %s, line %d.",
bits, BN_num_bits(key->rsa->n), filename, linenum);
}
return 1;
}
/*
* Checks whether the given host (which must be in all lowercase) is already
* in the list of our known hosts. Returns HOST_OK if the host is known and
* has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
* if the host is known but used to have a different host key.
*/
HostStatus
check_host_in_hostfile(const char *filename, const char *host, Key *key, Key *found)
{
FILE *f;
char line[8192];
int linenum = 0;
unsigned int kbits, hostlen;
char *cp, *cp2;
HostStatus end_return;
if (key == NULL)
fatal("no key to look up");
/* Open the file containing the list of known hosts. */
f = fopen(filename, "r");
if (!f)
return HOST_NEW;
/* Cache the length of the host name. */
hostlen = strlen(host);
/*
* Return value when the loop terminates. This is set to
* HOST_CHANGED if we have seen a different key for the host and have
* not found the proper one.
*/
end_return = HOST_NEW;
/* Go trough the file. */
while (fgets(line, sizeof(line), f)) {
cp = line;
linenum++;
/* Skip any leading whitespace, comments and empty lines. */
for (; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '#' || *cp == '\n')
continue;
/* Find the end of the host name portion. */
for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
;
/* Check if the host name matches. */
if (!match_hostname(host, cp, (unsigned int) (cp2 - cp)))
continue;
/* Got a match. Skip host name. */
cp = cp2;
/*
* Extract the key from the line. This will skip any leading
* whitespace. Ignore badly formatted lines.
*/
if (!hostfile_read_key(&cp, &kbits, found))
continue;
if (!hostfile_check_key(kbits, found, host, filename, linenum))
continue;
/* Check if the current key is the same as the given key. */
if (key_equal(key, found)) {
/* Ok, they match. */
fclose(f);
return HOST_OK;
}
/*
* They do not match. We will continue to go through the
* file; however, we note that we will not return that it is
* new.
*/
end_return = HOST_CHANGED;
}
/* Clear variables and close the file. */
fclose(f);
/*
* Return either HOST_NEW or HOST_CHANGED, depending on whether we
* saw a different key for the host.
*/
return end_return;
}
/*
* Appends an entry to the host file. Returns false if the entry could not
* be appended.
*/
int
add_host_to_hostfile(const char *filename, const char *host, Key *key)
{
FILE *f;
int success = 0;
if (key == NULL)
return 1; /* XXX ? */
f = fopen(filename, "a");
if (!f)
return 0;
fprintf(f, "%s ", host);
if (key_write(key, f)) {
success = 1;
} else {
error("add_host_to_hostfile: saving key in %s failed", filename);
}
fprintf(f, "\n");
fclose(f);
return success;
}
|
