Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.28
1.28 ! stevesk 1: /* $OpenBSD: ssh-keysign.c,v 1.27 2006/07/22 20:48:23 stevesk Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2002 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25: #include "includes.h"
1.20 stevesk 26:
1.24 stevesk 27: #include <sys/types.h>
1.1 markus 28:
29: #include <openssl/evp.h>
1.6 markus 30: #include <openssl/rand.h>
31: #include <openssl/rsa.h>
1.24 stevesk 32:
1.25 stevesk 33: #include <fcntl.h>
1.24 stevesk 34: #include <paths.h>
35: #include <pwd.h>
1.28 ! stevesk 36: #include <stdlib.h>
1.27 stevesk 37: #include <string.h>
1.26 stevesk 38: #include <unistd.h>
1.1 markus 39:
40: #include "log.h"
41: #include "key.h"
1.7 markus 42: #include "ssh.h"
1.1 markus 43: #include "ssh2.h"
44: #include "misc.h"
45: #include "xmalloc.h"
46: #include "buffer.h"
47: #include "bufaux.h"
48: #include "authfile.h"
49: #include "msg.h"
1.2 markus 50: #include "canohost.h"
1.1 markus 51: #include "pathnames.h"
1.7 markus 52: #include "readconf.h"
1.17 dtucker 53: #include "uidswap.h"
1.7 markus 54:
1.12 djm 55: /* XXX readconf.c needs these */
56: uid_t original_real_uid;
1.1 markus 57:
58: static int
1.2 markus 59: valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
60: u_int datalen)
1.1 markus 61: {
62: Buffer b;
1.11 markus 63: Key *key = NULL;
1.2 markus 64: u_char *pkblob;
65: u_int blen, len;
66: char *pkalg, *p;
1.1 markus 67: int pktype, fail;
68:
69: fail = 0;
70:
71: buffer_init(&b);
72: buffer_append(&b, data, datalen);
1.4 deraadt 73:
1.23 dtucker 74: /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
1.3 markus 75: p = buffer_get_string(&b, &len);
1.23 dtucker 76: if (len != 20 && len != 32)
1.3 markus 77: fail++;
78: xfree(p);
79:
1.1 markus 80: if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
81: fail++;
82:
83: /* server user */
84: buffer_skip_string(&b);
85:
86: /* service */
87: p = buffer_get_string(&b, NULL);
88: if (strcmp("ssh-connection", p) != 0)
89: fail++;
90: xfree(p);
91:
92: /* method */
93: p = buffer_get_string(&b, NULL);
94: if (strcmp("hostbased", p) != 0)
95: fail++;
96: xfree(p);
97:
98: /* pubkey */
99: pkalg = buffer_get_string(&b, NULL);
100: pkblob = buffer_get_string(&b, &blen);
101:
102: pktype = key_type_from_name(pkalg);
103: if (pktype == KEY_UNSPEC)
104: fail++;
105: else if ((key = key_from_blob(pkblob, blen)) == NULL)
106: fail++;
107: else if (key->type != pktype)
108: fail++;
109: xfree(pkalg);
110: xfree(pkblob);
111:
1.2 markus 112: /* client host name, handle trailing dot */
113: p = buffer_get_string(&b, &len);
114: debug2("valid_request: check expect chost %s got %s", host, p);
115: if (strlen(host) != len - 1)
116: fail++;
117: else if (p[len - 1] != '.')
1.4 deraadt 118: fail++;
1.2 markus 119: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 120: fail++;
1.2 markus 121: xfree(p);
1.1 markus 122:
123: /* local user */
124: p = buffer_get_string(&b, NULL);
1.2 markus 125:
1.1 markus 126: if (strcmp(pw->pw_name, p) != 0)
127: fail++;
128: xfree(p);
129:
130: /* end of message */
131: if (buffer_len(&b) != 0)
132: fail++;
1.15 markus 133: buffer_free(&b);
1.1 markus 134:
135: debug3("valid_request: fail %d", fail);
136:
137: if (fail && key != NULL)
138: key_free(key);
139: else
140: *ret = key;
141:
142: return (fail ? -1 : 0);
143: }
144:
145: int
146: main(int argc, char **argv)
147: {
148: Buffer b;
1.7 markus 149: Options options;
1.1 markus 150: Key *keys[2], *key;
151: struct passwd *pw;
1.2 markus 152: int key_fd[2], i, found, version = 2, fd;
1.1 markus 153: u_char *signature, *data;
1.2 markus 154: char *host;
1.1 markus 155: u_int slen, dlen;
1.6 markus 156: u_int32_t rnd[256];
1.19 djm 157:
158: /* Ensure that stdin and stdout are connected */
159: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
160: exit(1);
161: /* Leave /dev/null fd iff it is attached to stderr */
162: if (fd > 2)
163: close(fd);
1.1 markus 164:
165: key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
166: key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
167:
1.18 dtucker 168: original_real_uid = getuid(); /* XXX readconf.c needs this */
169: if ((pw = getpwuid(original_real_uid)) == NULL)
1.17 dtucker 170: fatal("getpwuid failed");
171: pw = pwcopy(pw);
172:
173: permanently_set_uid(pw);
1.1 markus 174:
175: #ifdef DEBUG_SSH_KEYSIGN
176: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 177: #endif
1.7 markus 178:
179: /* verify that ssh-keysign is enabled by the admin */
180: initialize_options(&options);
1.16 djm 181: (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
1.7 markus 182: fill_default_options(&options);
1.8 markus 183: if (options.enable_ssh_keysign != 1)
184: fatal("ssh-keysign not enabled in %s",
1.7 markus 185: _PATH_HOST_CONFIG_FILE);
1.1 markus 186:
187: if (key_fd[0] == -1 && key_fd[1] == -1)
188: fatal("could not open any host key");
189:
190: SSLeay_add_all_algorithms();
1.6 markus 191: for (i = 0; i < 256; i++)
192: rnd[i] = arc4random();
193: RAND_seed(rnd, sizeof(rnd));
1.1 markus 194:
195: found = 0;
196: for (i = 0; i < 2; i++) {
197: keys[i] = NULL;
198: if (key_fd[i] == -1)
199: continue;
200: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
201: NULL, NULL);
202: close(key_fd[i]);
203: if (keys[i] != NULL)
204: found = 1;
205: }
206: if (!found)
207: fatal("no hostkey found");
208:
209: buffer_init(&b);
1.9 djm 210: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
211: fatal("ssh_msg_recv failed");
1.1 markus 212: if (buffer_get_char(&b) != version)
213: fatal("bad version");
1.2 markus 214: fd = buffer_get_int(&b);
215: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
216: fatal("bad fd");
217: if ((host = get_local_name(fd)) == NULL)
218: fatal("cannot get sockname for fd");
1.4 deraadt 219:
1.1 markus 220: data = buffer_get_string(&b, &dlen);
1.2 markus 221: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 222: fatal("not a valid request");
1.2 markus 223: xfree(host);
1.1 markus 224:
225: found = 0;
226: for (i = 0; i < 2; i++) {
227: if (keys[i] != NULL &&
228: key_equal(key, keys[i])) {
229: found = 1;
230: break;
231: }
232: }
233: if (!found)
234: fatal("no matching hostkey found");
235:
236: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
237: fatal("key_sign failed");
1.5 markus 238: xfree(data);
1.4 deraadt 239:
1.1 markus 240: /* send reply */
241: buffer_clear(&b);
242: buffer_put_string(&b, signature, slen);
1.14 djm 243: if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
244: fatal("ssh_msg_send failed");
1.1 markus 245:
246: return (0);
247: }
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