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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" | |
25 | RCSID("$OpenBSD: ssh-keysign.c,v 1.2 2002/05/31 10:30:33 markus Exp $"); | |
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 | ||
41 | static int | |
42 | valid_request(struct passwd *pw, char *host, Key **ret, u_char *data, | |
43 | u_int datalen) | |
44 | { | |
45 | Buffer b; | |
46 | Key *key; | |
47 | u_char *pkblob; | |
48 | u_int blen, len; | |
49 | char *pkalg, *p; | |
50 | int pktype, fail; | |
51 | ||
52 | fail = 0; | |
53 | ||
54 | buffer_init(&b); | |
55 | buffer_append(&b, data, datalen); | |
56 | ||
57 | /* session id */ | |
58 | buffer_skip_string(&b); | |
59 | if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) | |
60 | fail++; | |
61 | ||
62 | /* server user */ | |
63 | buffer_skip_string(&b); | |
64 | ||
65 | /* service */ | |
66 | p = buffer_get_string(&b, NULL); | |
67 | if (strcmp("ssh-connection", p) != 0) | |
68 | fail++; | |
69 | xfree(p); | |
70 | ||
71 | /* method */ | |
72 | p = buffer_get_string(&b, NULL); | |
73 | if (strcmp("hostbased", p) != 0) | |
74 | fail++; | |
75 | xfree(p); | |
76 | ||
77 | /* pubkey */ | |
78 | pkalg = buffer_get_string(&b, NULL); | |
79 | pkblob = buffer_get_string(&b, &blen); | |
80 | ||
81 | pktype = key_type_from_name(pkalg); | |
82 | if (pktype == KEY_UNSPEC) | |
83 | fail++; | |
84 | else if ((key = key_from_blob(pkblob, blen)) == NULL) | |
85 | fail++; | |
86 | else if (key->type != pktype) | |
87 | fail++; | |
88 | xfree(pkalg); | |
89 | xfree(pkblob); | |
90 | ||
91 | /* client host name, handle trailing dot */ | |
92 | p = buffer_get_string(&b, &len); | |
93 | debug2("valid_request: check expect chost %s got %s", host, p); | |
94 | if (strlen(host) != len - 1) | |
95 | fail++; | |
96 | else if (p[len - 1] != '.') | |
97 | fail++; | |
98 | else if (strncasecmp(host, p, len - 1) != 0) | |
99 | fail++; | |
100 | xfree(p); | |
101 | ||
102 | /* local user */ | |
103 | p = buffer_get_string(&b, NULL); | |
104 | ||
105 | if (strcmp(pw->pw_name, p) != 0) | |
106 | fail++; | |
107 | xfree(p); | |
108 | ||
109 | /* end of message */ | |
110 | if (buffer_len(&b) != 0) | |
111 | fail++; | |
112 | ||
113 | debug3("valid_request: fail %d", fail); | |
114 | ||
115 | if (fail && key != NULL) | |
116 | key_free(key); | |
117 | else | |
118 | *ret = key; | |
119 | ||
120 | return (fail ? -1 : 0); | |
121 | } | |
122 | ||
123 | int | |
124 | main(int argc, char **argv) | |
125 | { | |
126 | Buffer b; | |
127 | Key *keys[2], *key; | |
128 | struct passwd *pw; | |
129 | int key_fd[2], i, found, version = 2, fd; | |
130 | u_char *signature, *data; | |
131 | char *host; | |
132 | u_int slen, dlen; | |
133 | ||
134 | key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY); | |
135 | key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY); | |
136 | ||
137 | seteuid(getuid()); | |
138 | setuid(getuid()); | |
139 | ||
04eb391d | 140 | init_rng(); |
141 | seed_rng(); | |
142 | arc4random_stir(); | |
143 | ||
39c00dc2 | 144 | #ifdef DEBUG_SSH_KEYSIGN |
145 | log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0); | |
146 | #endif | |
147 | ||
148 | if (key_fd[0] == -1 && key_fd[1] == -1) | |
149 | fatal("could not open any host key"); | |
150 | ||
151 | if ((pw = getpwuid(getuid())) == NULL) | |
152 | fatal("getpwuid failed"); | |
153 | pw = pwcopy(pw); | |
154 | ||
155 | SSLeay_add_all_algorithms(); | |
156 | ||
157 | found = 0; | |
158 | for (i = 0; i < 2; i++) { | |
159 | keys[i] = NULL; | |
160 | if (key_fd[i] == -1) | |
161 | continue; | |
162 | keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC, | |
163 | NULL, NULL); | |
164 | close(key_fd[i]); | |
165 | if (keys[i] != NULL) | |
166 | found = 1; | |
167 | } | |
168 | if (!found) | |
169 | fatal("no hostkey found"); | |
170 | ||
171 | buffer_init(&b); | |
172 | if (msg_recv(STDIN_FILENO, &b) < 0) | |
173 | fatal("msg_recv failed"); | |
174 | if (buffer_get_char(&b) != version) | |
175 | fatal("bad version"); | |
176 | fd = buffer_get_int(&b); | |
177 | if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO)) | |
178 | fatal("bad fd"); | |
179 | if ((host = get_local_name(fd)) == NULL) | |
180 | fatal("cannot get sockname for fd"); | |
181 | ||
182 | data = buffer_get_string(&b, &dlen); | |
183 | if (valid_request(pw, host, &key, data, dlen) < 0) | |
184 | fatal("not a valid request"); | |
185 | xfree(data); | |
186 | xfree(host); | |
187 | ||
188 | found = 0; | |
189 | for (i = 0; i < 2; i++) { | |
190 | if (keys[i] != NULL && | |
191 | key_equal(key, keys[i])) { | |
192 | found = 1; | |
193 | break; | |
194 | } | |
195 | } | |
196 | if (!found) | |
197 | fatal("no matching hostkey found"); | |
198 | ||
199 | if (key_sign(keys[i], &signature, &slen, data, dlen) != 0) | |
200 | fatal("key_sign failed"); | |
201 | ||
202 | /* send reply */ | |
203 | buffer_clear(&b); | |
204 | buffer_put_string(&b, signature, slen); | |
205 | msg_send(STDOUT_FILENO, version, &b); | |
206 | ||
207 | return (0); | |
208 | } |