Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.27
1.27 ! stevesk 1: /* $OpenBSD: ssh-keysign.c,v 1.26 2006/07/17 01:31:10 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>
1.27 ! stevesk 36: #include <string.h>
1.26 stevesk 37: #include <unistd.h>
1.1 markus 38:
39: #include "log.h"
40: #include "key.h"
1.7 markus 41: #include "ssh.h"
1.1 markus 42: #include "ssh2.h"
43: #include "misc.h"
44: #include "xmalloc.h"
45: #include "buffer.h"
46: #include "bufaux.h"
47: #include "authfile.h"
48: #include "msg.h"
1.2 markus 49: #include "canohost.h"
1.1 markus 50: #include "pathnames.h"
1.7 markus 51: #include "readconf.h"
1.17 dtucker 52: #include "uidswap.h"
1.7 markus 53:
1.12 djm 54: /* XXX readconf.c needs these */
55: uid_t original_real_uid;
1.1 markus 56:
57: static int
1.2 markus 58: valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
59: u_int datalen)
1.1 markus 60: {
61: Buffer b;
1.11 markus 62: Key *key = NULL;
1.2 markus 63: u_char *pkblob;
64: u_int blen, len;
65: char *pkalg, *p;
1.1 markus 66: int pktype, fail;
67:
68: fail = 0;
69:
70: buffer_init(&b);
71: buffer_append(&b, data, datalen);
1.4 deraadt 72:
1.23 dtucker 73: /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
1.3 markus 74: p = buffer_get_string(&b, &len);
1.23 dtucker 75: if (len != 20 && len != 32)
1.3 markus 76: fail++;
77: xfree(p);
78:
1.1 markus 79: if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
80: fail++;
81:
82: /* server user */
83: buffer_skip_string(&b);
84:
85: /* service */
86: p = buffer_get_string(&b, NULL);
87: if (strcmp("ssh-connection", p) != 0)
88: fail++;
89: xfree(p);
90:
91: /* method */
92: p = buffer_get_string(&b, NULL);
93: if (strcmp("hostbased", p) != 0)
94: fail++;
95: xfree(p);
96:
97: /* pubkey */
98: pkalg = buffer_get_string(&b, NULL);
99: pkblob = buffer_get_string(&b, &blen);
100:
101: pktype = key_type_from_name(pkalg);
102: if (pktype == KEY_UNSPEC)
103: fail++;
104: else if ((key = key_from_blob(pkblob, blen)) == NULL)
105: fail++;
106: else if (key->type != pktype)
107: fail++;
108: xfree(pkalg);
109: xfree(pkblob);
110:
1.2 markus 111: /* client host name, handle trailing dot */
112: p = buffer_get_string(&b, &len);
113: debug2("valid_request: check expect chost %s got %s", host, p);
114: if (strlen(host) != len - 1)
115: fail++;
116: else if (p[len - 1] != '.')
1.4 deraadt 117: fail++;
1.2 markus 118: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 119: fail++;
1.2 markus 120: xfree(p);
1.1 markus 121:
122: /* local user */
123: p = buffer_get_string(&b, NULL);
1.2 markus 124:
1.1 markus 125: if (strcmp(pw->pw_name, p) != 0)
126: fail++;
127: xfree(p);
128:
129: /* end of message */
130: if (buffer_len(&b) != 0)
131: fail++;
1.15 markus 132: buffer_free(&b);
1.1 markus 133:
134: debug3("valid_request: fail %d", fail);
135:
136: if (fail && key != NULL)
137: key_free(key);
138: else
139: *ret = key;
140:
141: return (fail ? -1 : 0);
142: }
143:
144: int
145: main(int argc, char **argv)
146: {
147: Buffer b;
1.7 markus 148: Options options;
1.1 markus 149: Key *keys[2], *key;
150: struct passwd *pw;
1.2 markus 151: int key_fd[2], 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:
164: key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
165: key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
166:
1.18 dtucker 167: original_real_uid = getuid(); /* XXX readconf.c needs this */
168: if ((pw = getpwuid(original_real_uid)) == NULL)
1.17 dtucker 169: fatal("getpwuid failed");
170: pw = pwcopy(pw);
171:
172: permanently_set_uid(pw);
1.1 markus 173:
174: #ifdef DEBUG_SSH_KEYSIGN
175: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 176: #endif
1.7 markus 177:
178: /* verify that ssh-keysign is enabled by the admin */
179: initialize_options(&options);
1.16 djm 180: (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
1.7 markus 181: fill_default_options(&options);
1.8 markus 182: if (options.enable_ssh_keysign != 1)
183: fatal("ssh-keysign not enabled in %s",
1.7 markus 184: _PATH_HOST_CONFIG_FILE);
1.1 markus 185:
186: if (key_fd[0] == -1 && key_fd[1] == -1)
187: fatal("could not open any host key");
188:
189: SSLeay_add_all_algorithms();
1.6 markus 190: for (i = 0; i < 256; i++)
191: rnd[i] = arc4random();
192: RAND_seed(rnd, sizeof(rnd));
1.1 markus 193:
194: found = 0;
195: for (i = 0; i < 2; i++) {
196: keys[i] = NULL;
197: if (key_fd[i] == -1)
198: continue;
199: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
200: NULL, NULL);
201: close(key_fd[i]);
202: if (keys[i] != NULL)
203: found = 1;
204: }
205: if (!found)
206: fatal("no hostkey found");
207:
208: buffer_init(&b);
1.9 djm 209: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
210: fatal("ssh_msg_recv failed");
1.1 markus 211: if (buffer_get_char(&b) != version)
212: fatal("bad version");
1.2 markus 213: fd = buffer_get_int(&b);
214: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
215: fatal("bad fd");
216: if ((host = get_local_name(fd)) == NULL)
217: fatal("cannot get sockname for fd");
1.4 deraadt 218:
1.1 markus 219: data = buffer_get_string(&b, &dlen);
1.2 markus 220: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 221: fatal("not a valid request");
1.2 markus 222: xfree(host);
1.1 markus 223:
224: found = 0;
225: for (i = 0; i < 2; i++) {
226: if (keys[i] != NULL &&
227: key_equal(key, keys[i])) {
228: found = 1;
229: break;
230: }
231: }
232: if (!found)
233: fatal("no matching hostkey found");
234:
235: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
236: fatal("key_sign failed");
1.5 markus 237: xfree(data);
1.4 deraadt 238:
1.1 markus 239: /* send reply */
240: buffer_clear(&b);
241: buffer_put_string(&b, signature, slen);
1.14 djm 242: if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
243: fatal("ssh_msg_send failed");
1.1 markus 244:
245: return (0);
246: }
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