Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.37
1.37 ! djm 1: /* $OpenBSD: ssh-keysign.c,v 1.36 2011/02/16 00:31:14 djm 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: */
1.20 stevesk 25:
1.24 stevesk 26: #include <sys/types.h>
1.1 markus 27:
28: #include <openssl/evp.h>
1.6 markus 29: #include <openssl/rand.h>
30: #include <openssl/rsa.h>
1.24 stevesk 31:
1.25 stevesk 32: #include <fcntl.h>
1.24 stevesk 33: #include <paths.h>
34: #include <pwd.h>
1.28 stevesk 35: #include <stdlib.h>
1.27 stevesk 36: #include <string.h>
1.26 stevesk 37: #include <unistd.h>
1.1 markus 38:
1.29 deraadt 39: #include "xmalloc.h"
1.1 markus 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 "buffer.h"
46: #include "authfile.h"
47: #include "msg.h"
1.2 markus 48: #include "canohost.h"
1.1 markus 49: #include "pathnames.h"
1.7 markus 50: #include "readconf.h"
1.17 dtucker 51: #include "uidswap.h"
1.7 markus 52:
1.12 djm 53: /* XXX readconf.c needs these */
54: uid_t original_real_uid;
1.1 markus 55:
56: static int
1.2 markus 57: valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
58: u_int datalen)
1.1 markus 59: {
60: Buffer b;
1.11 markus 61: Key *key = NULL;
1.2 markus 62: u_char *pkblob;
63: u_int blen, len;
64: char *pkalg, *p;
1.1 markus 65: int pktype, fail;
66:
67: fail = 0;
68:
69: buffer_init(&b);
70: buffer_append(&b, data, datalen);
1.4 deraadt 71:
1.23 dtucker 72: /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
1.3 markus 73: p = buffer_get_string(&b, &len);
1.23 dtucker 74: if (len != 20 && len != 32)
1.3 markus 75: fail++;
1.37 ! djm 76: free(p);
1.3 markus 77:
1.1 markus 78: if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
79: fail++;
80:
81: /* server user */
82: buffer_skip_string(&b);
83:
84: /* service */
85: p = buffer_get_string(&b, NULL);
86: if (strcmp("ssh-connection", p) != 0)
87: fail++;
1.37 ! djm 88: free(p);
1.1 markus 89:
90: /* method */
91: p = buffer_get_string(&b, NULL);
92: if (strcmp("hostbased", p) != 0)
93: fail++;
1.37 ! djm 94: free(p);
1.1 markus 95:
96: /* pubkey */
97: pkalg = buffer_get_string(&b, NULL);
98: pkblob = buffer_get_string(&b, &blen);
99:
100: pktype = key_type_from_name(pkalg);
101: if (pktype == KEY_UNSPEC)
102: fail++;
103: else if ((key = key_from_blob(pkblob, blen)) == NULL)
104: fail++;
105: else if (key->type != pktype)
106: fail++;
1.37 ! djm 107: free(pkalg);
! 108: free(pkblob);
1.1 markus 109:
1.2 markus 110: /* client host name, handle trailing dot */
111: p = buffer_get_string(&b, &len);
112: debug2("valid_request: check expect chost %s got %s", host, p);
113: if (strlen(host) != len - 1)
114: fail++;
115: else if (p[len - 1] != '.')
1.4 deraadt 116: fail++;
1.2 markus 117: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 118: fail++;
1.37 ! djm 119: free(p);
1.1 markus 120:
121: /* local user */
122: p = buffer_get_string(&b, NULL);
1.2 markus 123:
1.1 markus 124: if (strcmp(pw->pw_name, p) != 0)
125: fail++;
1.37 ! djm 126: free(p);
1.1 markus 127:
128: /* end of message */
129: if (buffer_len(&b) != 0)
130: fail++;
1.15 markus 131: buffer_free(&b);
1.1 markus 132:
133: debug3("valid_request: fail %d", fail);
134:
135: if (fail && key != NULL)
136: key_free(key);
137: else
138: *ret = key;
139:
140: return (fail ? -1 : 0);
141: }
142:
143: int
144: main(int argc, char **argv)
145: {
146: Buffer b;
1.7 markus 147: Options options;
1.36 djm 148: #define NUM_KEYTYPES 3
149: Key *keys[NUM_KEYTYPES], *key = NULL;
1.1 markus 150: struct passwd *pw;
1.36 djm 151: int key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
1.1 markus 152: u_char *signature, *data;
1.2 markus 153: char *host;
1.1 markus 154: u_int slen, dlen;
1.6 markus 155: u_int32_t rnd[256];
1.19 djm 156:
157: /* Ensure that stdin and stdout are connected */
158: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
159: exit(1);
160: /* Leave /dev/null fd iff it is attached to stderr */
161: if (fd > 2)
162: close(fd);
1.1 markus 163:
1.36 djm 164: i = 0;
165: key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
166: key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
167: key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
1.1 markus 168:
1.18 dtucker 169: original_real_uid = getuid(); /* XXX readconf.c needs this */
170: if ((pw = getpwuid(original_real_uid)) == NULL)
1.17 dtucker 171: fatal("getpwuid failed");
172: pw = pwcopy(pw);
173:
174: permanently_set_uid(pw);
1.1 markus 175:
176: #ifdef DEBUG_SSH_KEYSIGN
177: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 178: #endif
1.7 markus 179:
180: /* verify that ssh-keysign is enabled by the admin */
181: initialize_options(&options);
1.16 djm 182: (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
1.7 markus 183: fill_default_options(&options);
1.8 markus 184: if (options.enable_ssh_keysign != 1)
185: fatal("ssh-keysign not enabled in %s",
1.7 markus 186: _PATH_HOST_CONFIG_FILE);
1.1 markus 187:
1.36 djm 188: for (i = found = 0; i < NUM_KEYTYPES; i++) {
189: if (key_fd[i] != -1)
190: found = 1;
191: }
192: if (found == 0)
1.1 markus 193: fatal("could not open any host key");
194:
1.35 djm 195: OpenSSL_add_all_algorithms();
1.6 markus 196: for (i = 0; i < 256; i++)
197: rnd[i] = arc4random();
198: RAND_seed(rnd, sizeof(rnd));
1.1 markus 199:
200: found = 0;
1.36 djm 201: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 202: keys[i] = NULL;
203: if (key_fd[i] == -1)
204: continue;
205: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
206: NULL, NULL);
207: close(key_fd[i]);
208: if (keys[i] != NULL)
209: found = 1;
210: }
211: if (!found)
212: fatal("no hostkey found");
213:
214: buffer_init(&b);
1.9 djm 215: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
216: fatal("ssh_msg_recv failed");
1.1 markus 217: if (buffer_get_char(&b) != version)
218: fatal("bad version");
1.2 markus 219: fd = buffer_get_int(&b);
220: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
221: fatal("bad fd");
222: if ((host = get_local_name(fd)) == NULL)
1.30 dtucker 223: fatal("cannot get local name for fd");
1.4 deraadt 224:
1.1 markus 225: data = buffer_get_string(&b, &dlen);
1.2 markus 226: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 227: fatal("not a valid request");
1.37 ! djm 228: free(host);
1.1 markus 229:
230: found = 0;
1.36 djm 231: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 232: if (keys[i] != NULL &&
1.31 djm 233: key_equal_public(key, keys[i])) {
1.1 markus 234: found = 1;
235: break;
236: }
237: }
238: if (!found)
239: fatal("no matching hostkey found");
240:
241: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
242: fatal("key_sign failed");
1.37 ! djm 243: free(data);
1.4 deraadt 244:
1.1 markus 245: /* send reply */
246: buffer_clear(&b);
247: buffer_put_string(&b, signature, slen);
1.14 djm 248: if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
249: fatal("ssh_msg_send failed");
1.1 markus 250:
251: return (0);
252: }
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