Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.7.2.2
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"
1.7.2.2 ! brad 25: RCSID("$OpenBSD: ssh-keysign.c,v 1.13 2003/07/03 08:09:06 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:
1.7.2.2 ! brad 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;
1.7.2.2 ! brad 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++;
123:
124: debug3("valid_request: fail %d", fail);
125:
126: if (fail && key != NULL)
127: key_free(key);
128: else
129: *ret = key;
130:
131: return (fail ? -1 : 0);
132: }
133:
134: int
135: main(int argc, char **argv)
136: {
137: Buffer b;
1.7 markus 138: Options options;
1.1 markus 139: Key *keys[2], *key;
140: struct passwd *pw;
1.2 markus 141: int key_fd[2], i, found, version = 2, fd;
1.1 markus 142: u_char *signature, *data;
1.2 markus 143: char *host;
1.1 markus 144: u_int slen, dlen;
1.6 markus 145: u_int32_t rnd[256];
1.1 markus 146:
147: key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
148: key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
149:
150: seteuid(getuid());
151: setuid(getuid());
152:
153: #ifdef DEBUG_SSH_KEYSIGN
154: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 155: #endif
1.7 markus 156:
157: /* verify that ssh-keysign is enabled by the admin */
158: original_real_uid = getuid(); /* XXX readconf.c needs this */
159: initialize_options(&options);
160: (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
161: fill_default_options(&options);
1.7.2.1 margarid 162: if (options.enable_ssh_keysign != 1)
163: fatal("ssh-keysign not enabled in %s",
1.7 markus 164: _PATH_HOST_CONFIG_FILE);
1.1 markus 165:
166: if (key_fd[0] == -1 && key_fd[1] == -1)
167: fatal("could not open any host key");
168:
169: if ((pw = getpwuid(getuid())) == NULL)
170: fatal("getpwuid failed");
1.4 deraadt 171: pw = pwcopy(pw);
1.1 markus 172:
173: SSLeay_add_all_algorithms();
1.6 markus 174: for (i = 0; i < 256; i++)
175: rnd[i] = arc4random();
176: RAND_seed(rnd, sizeof(rnd));
1.1 markus 177:
178: found = 0;
179: for (i = 0; i < 2; i++) {
180: keys[i] = NULL;
181: if (key_fd[i] == -1)
182: continue;
183: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
184: NULL, NULL);
185: close(key_fd[i]);
186: if (keys[i] != NULL)
187: found = 1;
188: }
189: if (!found)
190: fatal("no hostkey found");
191:
192: buffer_init(&b);
1.7.2.1 margarid 193: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
194: fatal("ssh_msg_recv failed");
1.1 markus 195: if (buffer_get_char(&b) != version)
196: fatal("bad version");
1.2 markus 197: fd = buffer_get_int(&b);
198: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
199: fatal("bad fd");
200: if ((host = get_local_name(fd)) == NULL)
201: fatal("cannot get sockname for fd");
1.4 deraadt 202:
1.1 markus 203: data = buffer_get_string(&b, &dlen);
1.2 markus 204: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 205: fatal("not a valid request");
1.2 markus 206: xfree(host);
1.1 markus 207:
208: found = 0;
209: for (i = 0; i < 2; i++) {
210: if (keys[i] != NULL &&
211: key_equal(key, keys[i])) {
212: found = 1;
213: break;
214: }
215: }
216: if (!found)
217: fatal("no matching hostkey found");
218:
219: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
220: fatal("key_sign failed");
1.5 markus 221: xfree(data);
1.4 deraadt 222:
1.1 markus 223: /* send reply */
224: buffer_clear(&b);
225: buffer_put_string(&b, signature, slen);
1.7.2.1 margarid 226: ssh_msg_send(STDOUT_FILENO, version, &b);
1.1 markus 227:
228: return (0);
229: }