Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.15
1.1 markus 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"
1.15 ! markus 25: RCSID("$OpenBSD: ssh-keysign.c,v 1.14 2003/11/17 09:45:39 djm Exp $");
1.1 markus 26:
27: #include <openssl/evp.h>
1.6 markus 28: #include <openssl/rand.h>
29: #include <openssl/rsa.h>
1.1 markus 30:
31: #include "log.h"
32: #include "key.h"
1.7 markus 33: #include "ssh.h"
1.1 markus 34: #include "ssh2.h"
35: #include "misc.h"
36: #include "xmalloc.h"
37: #include "buffer.h"
38: #include "bufaux.h"
39: #include "authfile.h"
40: #include "msg.h"
1.2 markus 41: #include "canohost.h"
1.1 markus 42: #include "pathnames.h"
1.7 markus 43: #include "readconf.h"
44:
1.12 djm 45: /* XXX readconf.c needs these */
46: uid_t original_real_uid;
1.1 markus 47:
48: static int
1.2 markus 49: valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
50: u_int datalen)
1.1 markus 51: {
52: Buffer b;
1.11 markus 53: Key *key = NULL;
1.2 markus 54: u_char *pkblob;
55: u_int blen, len;
56: char *pkalg, *p;
1.1 markus 57: int pktype, fail;
58:
59: fail = 0;
60:
61: buffer_init(&b);
62: buffer_append(&b, data, datalen);
1.4 deraadt 63:
1.3 markus 64: /* session id, currently limited to SHA1 (20 bytes) */
65: p = buffer_get_string(&b, &len);
66: if (len != 20)
67: fail++;
68: xfree(p);
69:
1.1 markus 70: if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
71: fail++;
72:
73: /* server user */
74: buffer_skip_string(&b);
75:
76: /* service */
77: p = buffer_get_string(&b, NULL);
78: if (strcmp("ssh-connection", p) != 0)
79: fail++;
80: xfree(p);
81:
82: /* method */
83: p = buffer_get_string(&b, NULL);
84: if (strcmp("hostbased", p) != 0)
85: fail++;
86: xfree(p);
87:
88: /* pubkey */
89: pkalg = buffer_get_string(&b, NULL);
90: pkblob = buffer_get_string(&b, &blen);
91:
92: pktype = key_type_from_name(pkalg);
93: if (pktype == KEY_UNSPEC)
94: fail++;
95: else if ((key = key_from_blob(pkblob, blen)) == NULL)
96: fail++;
97: else if (key->type != pktype)
98: fail++;
99: xfree(pkalg);
100: xfree(pkblob);
101:
1.2 markus 102: /* client host name, handle trailing dot */
103: p = buffer_get_string(&b, &len);
104: debug2("valid_request: check expect chost %s got %s", host, p);
105: if (strlen(host) != len - 1)
106: fail++;
107: else if (p[len - 1] != '.')
1.4 deraadt 108: fail++;
1.2 markus 109: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 110: fail++;
1.2 markus 111: xfree(p);
1.1 markus 112:
113: /* local user */
114: p = buffer_get_string(&b, NULL);
1.2 markus 115:
1.1 markus 116: if (strcmp(pw->pw_name, p) != 0)
117: fail++;
118: xfree(p);
119:
120: /* end of message */
121: if (buffer_len(&b) != 0)
122: fail++;
1.15 ! markus 123: buffer_free(&b);
1.1 markus 124:
125: debug3("valid_request: fail %d", fail);
126:
127: if (fail && key != NULL)
128: key_free(key);
129: else
130: *ret = key;
131:
132: return (fail ? -1 : 0);
133: }
134:
135: int
136: main(int argc, char **argv)
137: {
138: Buffer b;
1.7 markus 139: Options options;
1.1 markus 140: Key *keys[2], *key;
141: struct passwd *pw;
1.2 markus 142: int key_fd[2], i, found, version = 2, fd;
1.1 markus 143: u_char *signature, *data;
1.2 markus 144: char *host;
1.1 markus 145: u_int slen, dlen;
1.6 markus 146: u_int32_t rnd[256];
1.1 markus 147:
148: key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
149: key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
150:
151: seteuid(getuid());
152: setuid(getuid());
153:
154: #ifdef DEBUG_SSH_KEYSIGN
155: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 156: #endif
1.7 markus 157:
158: /* verify that ssh-keysign is enabled by the admin */
159: original_real_uid = getuid(); /* XXX readconf.c needs this */
160: initialize_options(&options);
161: (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
162: fill_default_options(&options);
1.8 markus 163: if (options.enable_ssh_keysign != 1)
164: fatal("ssh-keysign not enabled in %s",
1.7 markus 165: _PATH_HOST_CONFIG_FILE);
1.1 markus 166:
167: if (key_fd[0] == -1 && key_fd[1] == -1)
168: fatal("could not open any host key");
169:
170: if ((pw = getpwuid(getuid())) == NULL)
171: fatal("getpwuid failed");
1.4 deraadt 172: pw = pwcopy(pw);
1.1 markus 173:
174: SSLeay_add_all_algorithms();
1.6 markus 175: for (i = 0; i < 256; i++)
176: rnd[i] = arc4random();
177: RAND_seed(rnd, sizeof(rnd));
1.1 markus 178:
179: found = 0;
180: for (i = 0; i < 2; i++) {
181: keys[i] = NULL;
182: if (key_fd[i] == -1)
183: continue;
184: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
185: NULL, NULL);
186: close(key_fd[i]);
187: if (keys[i] != NULL)
188: found = 1;
189: }
190: if (!found)
191: fatal("no hostkey found");
192:
193: buffer_init(&b);
1.9 djm 194: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
195: fatal("ssh_msg_recv failed");
1.1 markus 196: if (buffer_get_char(&b) != version)
197: fatal("bad version");
1.2 markus 198: fd = buffer_get_int(&b);
199: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
200: fatal("bad fd");
201: if ((host = get_local_name(fd)) == NULL)
202: fatal("cannot get sockname for fd");
1.4 deraadt 203:
1.1 markus 204: data = buffer_get_string(&b, &dlen);
1.2 markus 205: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 206: fatal("not a valid request");
1.2 markus 207: xfree(host);
1.1 markus 208:
209: found = 0;
210: for (i = 0; i < 2; i++) {
211: if (keys[i] != NULL &&
212: key_equal(key, keys[i])) {
213: found = 1;
214: break;
215: }
216: }
217: if (!found)
218: fatal("no matching hostkey found");
219:
220: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
221: fatal("key_sign failed");
1.5 markus 222: xfree(data);
1.4 deraadt 223:
1.1 markus 224: /* send reply */
225: buffer_clear(&b);
226: buffer_put_string(&b, signature, slen);
1.14 djm 227: if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
228: fatal("ssh_msg_send failed");
1.1 markus 229:
230: return (0);
231: }
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