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39c00dc2 | 1 | /* |
2 | * Copyright (c) 2002 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | #include "includes.h" | |
7203d6bb | 25 | RCSID("$OpenBSD: ssh-keysign.c,v 1.4 2002/06/19 00:27:55 deraadt Exp $"); |
39c00dc2 | 26 | |
27 | #include <openssl/evp.h> | |
28 | ||
29 | #include "log.h" | |
30 | #include "key.h" | |
31 | #include "ssh2.h" | |
32 | #include "misc.h" | |
33 | #include "xmalloc.h" | |
34 | #include "buffer.h" | |
35 | #include "bufaux.h" | |
36 | #include "authfile.h" | |
37 | #include "msg.h" | |
38 | #include "canohost.h" | |
39 | #include "pathnames.h" | |
40 | ||
95d5ebf7 | 41 | #ifdef HAVE___PROGNAME |
42 | extern char *__progname; | |
43 | #else | |
44 | char *__progname; | |
45 | #endif | |
46 | ||
39c00dc2 | 47 | static int |
48 | valid_request(struct passwd *pw, char *host, Key **ret, u_char *data, | |
49 | u_int datalen) | |
50 | { | |
51 | Buffer b; | |
52 | Key *key; | |
53 | u_char *pkblob; | |
54 | u_int blen, len; | |
55 | char *pkalg, *p; | |
56 | int pktype, fail; | |
57 | ||
58 | fail = 0; | |
59 | ||
60 | buffer_init(&b); | |
61 | buffer_append(&b, data, datalen); | |
7203d6bb | 62 | |
1f143cf2 | 63 | /* session id, currently limited to SHA1 (20 bytes) */ |
64 | p = buffer_get_string(&b, &len); | |
65 | if (len != 20) | |
66 | fail++; | |
67 | xfree(p); | |
68 | ||
39c00dc2 | 69 | if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) |
70 | fail++; | |
71 | ||
72 | /* server user */ | |
73 | buffer_skip_string(&b); | |
74 | ||
75 | /* service */ | |
76 | p = buffer_get_string(&b, NULL); | |
77 | if (strcmp("ssh-connection", p) != 0) | |
78 | fail++; | |
79 | xfree(p); | |
80 | ||
81 | /* method */ | |
82 | p = buffer_get_string(&b, NULL); | |
83 | if (strcmp("hostbased", p) != 0) | |
84 | fail++; | |
85 | xfree(p); | |
86 | ||
87 | /* pubkey */ | |
88 | pkalg = buffer_get_string(&b, NULL); | |
89 | pkblob = buffer_get_string(&b, &blen); | |
90 | ||
91 | pktype = key_type_from_name(pkalg); | |
92 | if (pktype == KEY_UNSPEC) | |
93 | fail++; | |
94 | else if ((key = key_from_blob(pkblob, blen)) == NULL) | |
95 | fail++; | |
96 | else if (key->type != pktype) | |
97 | fail++; | |
98 | xfree(pkalg); | |
99 | xfree(pkblob); | |
100 | ||
101 | /* client host name, handle trailing dot */ | |
102 | p = buffer_get_string(&b, &len); | |
103 | debug2("valid_request: check expect chost %s got %s", host, p); | |
104 | if (strlen(host) != len - 1) | |
105 | fail++; | |
106 | else if (p[len - 1] != '.') | |
7203d6bb | 107 | fail++; |
39c00dc2 | 108 | else if (strncasecmp(host, p, len - 1) != 0) |
7203d6bb | 109 | fail++; |
39c00dc2 | 110 | xfree(p); |
111 | ||
112 | /* local user */ | |
113 | p = buffer_get_string(&b, NULL); | |
114 | ||
115 | if (strcmp(pw->pw_name, p) != 0) | |
116 | fail++; | |
117 | xfree(p); | |
118 | ||
119 | /* end of message */ | |
120 | if (buffer_len(&b) != 0) | |
121 | fail++; | |
122 | ||
123 | debug3("valid_request: fail %d", fail); | |
124 | ||
125 | if (fail && key != NULL) | |
126 | key_free(key); | |
127 | else | |
128 | *ret = key; | |
129 | ||
130 | return (fail ? -1 : 0); | |
131 | } | |
132 | ||
133 | int | |
134 | main(int argc, char **argv) | |
135 | { | |
136 | Buffer b; | |
137 | Key *keys[2], *key; | |
138 | struct passwd *pw; | |
139 | int key_fd[2], i, found, version = 2, fd; | |
140 | u_char *signature, *data; | |
141 | char *host; | |
142 | u_int slen, dlen; | |
143 | ||
144 | key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY); | |
145 | key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY); | |
146 | ||
147 | seteuid(getuid()); | |
148 | setuid(getuid()); | |
149 | ||
875ec275 | 150 | init_rng(); |
151 | seed_rng(); | |
152 | arc4random_stir(); | |
04eb391d | 153 | |
39c00dc2 | 154 | #ifdef DEBUG_SSH_KEYSIGN |
155 | log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0); | |
7203d6bb | 156 | #endif |
39c00dc2 | 157 | |
158 | if (key_fd[0] == -1 && key_fd[1] == -1) | |
159 | fatal("could not open any host key"); | |
160 | ||
161 | if ((pw = getpwuid(getuid())) == NULL) | |
162 | fatal("getpwuid failed"); | |
7203d6bb | 163 | pw = pwcopy(pw); |
39c00dc2 | 164 | |
165 | SSLeay_add_all_algorithms(); | |
166 | ||
167 | found = 0; | |
168 | for (i = 0; i < 2; i++) { | |
169 | keys[i] = NULL; | |
170 | if (key_fd[i] == -1) | |
171 | continue; | |
172 | keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC, | |
173 | NULL, NULL); | |
174 | close(key_fd[i]); | |
175 | if (keys[i] != NULL) | |
176 | found = 1; | |
177 | } | |
178 | if (!found) | |
179 | fatal("no hostkey found"); | |
180 | ||
181 | buffer_init(&b); | |
182 | if (msg_recv(STDIN_FILENO, &b) < 0) | |
183 | fatal("msg_recv failed"); | |
184 | if (buffer_get_char(&b) != version) | |
185 | fatal("bad version"); | |
186 | fd = buffer_get_int(&b); | |
187 | if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO)) | |
188 | fatal("bad fd"); | |
189 | if ((host = get_local_name(fd)) == NULL) | |
190 | fatal("cannot get sockname for fd"); | |
7203d6bb | 191 | |
39c00dc2 | 192 | data = buffer_get_string(&b, &dlen); |
193 | if (valid_request(pw, host, &key, data, dlen) < 0) | |
194 | fatal("not a valid request"); | |
195 | xfree(data); | |
196 | xfree(host); | |
197 | ||
198 | found = 0; | |
199 | for (i = 0; i < 2; i++) { | |
200 | if (keys[i] != NULL && | |
201 | key_equal(key, keys[i])) { | |
202 | found = 1; | |
203 | break; | |
204 | } | |
205 | } | |
206 | if (!found) | |
207 | fatal("no matching hostkey found"); | |
208 | ||
209 | if (key_sign(keys[i], &signature, &slen, data, dlen) != 0) | |
210 | fatal("key_sign failed"); | |
7203d6bb | 211 | |
39c00dc2 | 212 | /* send reply */ |
213 | buffer_clear(&b); | |
214 | buffer_put_string(&b, signature, slen); | |
215 | msg_send(STDOUT_FILENO, version, &b); | |
216 | ||
217 | return (0); | |
218 | } |