Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.44
1.44 ! djm 1: /* $OpenBSD: ssh-keysign.c,v 1.43 2014/10/08 22:20:25 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/rsa.h>
1.24 stevesk 30:
1.25 stevesk 31: #include <fcntl.h>
1.24 stevesk 32: #include <paths.h>
33: #include <pwd.h>
1.28 stevesk 34: #include <stdlib.h>
1.27 stevesk 35: #include <string.h>
1.26 stevesk 36: #include <unistd.h>
1.1 markus 37:
1.29 deraadt 38: #include "xmalloc.h"
1.1 markus 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 "buffer.h"
45: #include "authfile.h"
46: #include "msg.h"
1.2 markus 47: #include "canohost.h"
1.1 markus 48: #include "pathnames.h"
1.7 markus 49: #include "readconf.h"
1.17 dtucker 50: #include "uidswap.h"
1.7 markus 51:
1.12 djm 52: /* XXX readconf.c needs these */
53: uid_t original_real_uid;
1.1 markus 54:
55: static int
1.2 markus 56: valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
57: u_int datalen)
1.1 markus 58: {
59: Buffer b;
1.11 markus 60: Key *key = NULL;
1.2 markus 61: u_char *pkblob;
62: u_int blen, len;
63: char *pkalg, *p;
1.1 markus 64: int pktype, fail;
65:
66: fail = 0;
67:
68: buffer_init(&b);
69: buffer_append(&b, data, datalen);
1.4 deraadt 70:
1.23 dtucker 71: /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
1.3 markus 72: p = buffer_get_string(&b, &len);
1.23 dtucker 73: if (len != 20 && len != 32)
1.3 markus 74: fail++;
1.37 djm 75: free(p);
1.3 markus 76:
1.1 markus 77: if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
78: fail++;
79:
80: /* server user */
81: buffer_skip_string(&b);
82:
83: /* service */
84: p = buffer_get_string(&b, NULL);
85: if (strcmp("ssh-connection", p) != 0)
86: fail++;
1.37 djm 87: free(p);
1.1 markus 88:
89: /* method */
90: p = buffer_get_string(&b, NULL);
91: if (strcmp("hostbased", p) != 0)
92: fail++;
1.37 djm 93: free(p);
1.1 markus 94:
95: /* pubkey */
96: pkalg = buffer_get_string(&b, NULL);
97: pkblob = buffer_get_string(&b, &blen);
98:
99: pktype = key_type_from_name(pkalg);
100: if (pktype == KEY_UNSPEC)
101: fail++;
102: else if ((key = key_from_blob(pkblob, blen)) == NULL)
103: fail++;
104: else if (key->type != pktype)
105: fail++;
1.37 djm 106: free(pkalg);
107: free(pkblob);
1.1 markus 108:
1.2 markus 109: /* client host name, handle trailing dot */
110: p = buffer_get_string(&b, &len);
111: debug2("valid_request: check expect chost %s got %s", host, p);
112: if (strlen(host) != len - 1)
113: fail++;
114: else if (p[len - 1] != '.')
1.4 deraadt 115: fail++;
1.2 markus 116: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 117: fail++;
1.37 djm 118: free(p);
1.1 markus 119:
120: /* local user */
121: p = buffer_get_string(&b, NULL);
1.2 markus 122:
1.1 markus 123: if (strcmp(pw->pw_name, p) != 0)
124: fail++;
1.37 djm 125: free(p);
1.1 markus 126:
127: /* end of message */
128: if (buffer_len(&b) != 0)
129: fail++;
1.15 markus 130: buffer_free(&b);
1.1 markus 131:
132: debug3("valid_request: fail %d", fail);
133:
134: if (fail && key != NULL)
135: key_free(key);
136: else
137: *ret = key;
138:
139: return (fail ? -1 : 0);
140: }
141:
142: int
143: main(int argc, char **argv)
144: {
145: Buffer b;
1.7 markus 146: Options options;
1.39 markus 147: #define NUM_KEYTYPES 4
1.36 djm 148: Key *keys[NUM_KEYTYPES], *key = NULL;
1.1 markus 149: struct passwd *pw;
1.36 djm 150: int key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
1.1 markus 151: u_char *signature, *data;
1.40 djm 152: char *host, *fp;
1.1 markus 153: u_int slen, dlen;
1.19 djm 154:
155: /* Ensure that stdin and stdout are connected */
156: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
157: exit(1);
158: /* Leave /dev/null fd iff it is attached to stderr */
159: if (fd > 2)
160: close(fd);
1.1 markus 161:
1.36 djm 162: i = 0;
163: key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
164: key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
1.39 markus 165: key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
1.36 djm 166: key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
1.1 markus 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);
1.43 djm 181: (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "", &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:
1.36 djm 187: for (i = found = 0; i < NUM_KEYTYPES; i++) {
188: if (key_fd[i] != -1)
189: found = 1;
190: }
191: if (found == 0)
1.1 markus 192: fatal("could not open any host key");
193:
1.35 djm 194: OpenSSL_add_all_algorithms();
1.1 markus 195:
196: found = 0;
1.36 djm 197: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 198: keys[i] = NULL;
199: if (key_fd[i] == -1)
200: continue;
1.42 markus 201: #ifdef WITH_OPENSSL
202: /* XXX wrong api */
1.1 markus 203: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
204: NULL, NULL);
1.42 markus 205: #endif
1.1 markus 206: close(key_fd[i]);
207: if (keys[i] != NULL)
208: found = 1;
209: }
210: if (!found)
211: fatal("no hostkey found");
212:
213: buffer_init(&b);
1.9 djm 214: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
215: fatal("ssh_msg_recv failed");
1.1 markus 216: if (buffer_get_char(&b) != version)
217: fatal("bad version");
1.2 markus 218: fd = buffer_get_int(&b);
219: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
220: fatal("bad fd");
221: if ((host = get_local_name(fd)) == NULL)
1.30 dtucker 222: fatal("cannot get local name for fd");
1.4 deraadt 223:
1.1 markus 224: data = buffer_get_string(&b, &dlen);
1.2 markus 225: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 226: fatal("not a valid request");
1.37 djm 227: free(host);
1.1 markus 228:
229: found = 0;
1.36 djm 230: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 231: if (keys[i] != NULL &&
1.31 djm 232: key_equal_public(key, keys[i])) {
1.1 markus 233: found = 1;
234: break;
235: }
236: }
1.40 djm 237: if (!found) {
1.44 ! djm 238: fp = key_fingerprint(key, options.fingerprint_hash,
! 239: SSH_FP_DEFAULT);
1.40 djm 240: fatal("no matching hostkey found for key %s %s",
241: key_type(key), fp);
242: }
1.1 markus 243:
244: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
245: fatal("key_sign failed");
1.37 djm 246: free(data);
1.4 deraadt 247:
1.1 markus 248: /* send reply */
249: buffer_clear(&b);
250: buffer_put_string(&b, signature, slen);
1.14 djm 251: if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
252: fatal("ssh_msg_send failed");
1.1 markus 253:
254: return (0);
255: }