Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.46
1.46 ! djm 1: /* $OpenBSD: ssh-keysign.c,v 1.45 2015/01/08 10:14:08 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"
1.46 ! djm 40: #include "sshkey.h"
1.7 markus 41: #include "ssh.h"
1.1 markus 42: #include "ssh2.h"
43: #include "misc.h"
1.46 ! djm 44: #include "sshbuf.h"
1.1 markus 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"
1.45 djm 51: #include "sshkey.h"
52: #include "ssherr.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
1.46 ! djm 58: valid_request(struct passwd *pw, char *host, struct sshkey **ret,
! 59: u_char *data, size_t datalen)
1.1 markus 60: {
1.46 ! djm 61: struct sshbuf *b;
! 62: struct sshkey *key = NULL;
! 63: u_char type, *pkblob;
! 64: char *p;
! 65: size_t blen, len;
! 66: char *pkalg, *luser;
! 67: int r, pktype, fail;
1.1 markus 68:
1.45 djm 69: if (ret != NULL)
70: *ret = NULL;
1.1 markus 71: fail = 0;
72:
1.46 ! djm 73: if ((b = sshbuf_from(data, datalen)) == NULL)
! 74: fatal("%s: sshbuf_from failed", __func__);
1.4 deraadt 75:
1.23 dtucker 76: /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
1.46 ! djm 77: if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
! 78: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.23 dtucker 79: if (len != 20 && len != 32)
1.3 markus 80: fail++;
81:
1.46 ! djm 82: if ((r = sshbuf_get_u8(b, &type)) != 0)
! 83: fatal("%s: buffer error: %s", __func__, ssh_err(r));
! 84: if (type != SSH2_MSG_USERAUTH_REQUEST)
1.1 markus 85: fail++;
86:
87: /* server user */
1.46 ! djm 88: if ((r = sshbuf_skip_string(b)) != 0)
! 89: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 90:
91: /* service */
1.46 ! djm 92: if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
! 93: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 94: if (strcmp("ssh-connection", p) != 0)
95: fail++;
1.37 djm 96: free(p);
1.1 markus 97:
98: /* method */
1.46 ! djm 99: if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
! 100: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 101: if (strcmp("hostbased", p) != 0)
102: fail++;
1.37 djm 103: free(p);
1.1 markus 104:
105: /* pubkey */
1.46 ! djm 106: if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
! 107: (r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
! 108: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 109:
1.46 ! djm 110: pktype = sshkey_type_from_name(pkalg);
1.1 markus 111: if (pktype == KEY_UNSPEC)
112: fail++;
1.46 ! djm 113: else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
! 114: error("%s: bad key blob: %s", __func__, ssh_err(r));
1.1 markus 115: fail++;
1.46 ! djm 116: } else if (key->type != pktype)
1.1 markus 117: fail++;
1.37 djm 118: free(pkalg);
119: free(pkblob);
1.1 markus 120:
1.2 markus 121: /* client host name, handle trailing dot */
1.46 ! djm 122: if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
! 123: fatal("%s: buffer error: %s", __func__, ssh_err(r));
! 124: debug2("%s: check expect chost %s got %s", __func__, host, p);
1.2 markus 125: if (strlen(host) != len - 1)
126: fail++;
127: else if (p[len - 1] != '.')
1.4 deraadt 128: fail++;
1.2 markus 129: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 130: fail++;
1.37 djm 131: free(p);
1.1 markus 132:
133: /* local user */
1.46 ! djm 134: if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
! 135: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.2 markus 136:
1.46 ! djm 137: if (strcmp(pw->pw_name, luser) != 0)
1.1 markus 138: fail++;
1.46 ! djm 139: free(luser);
1.1 markus 140:
141: /* end of message */
1.46 ! djm 142: if (sshbuf_len(b) != 0)
1.1 markus 143: fail++;
1.46 ! djm 144: sshbuf_free(b);
1.1 markus 145:
1.46 ! djm 146: debug3("%s: fail %d", __func__, fail);
1.1 markus 147:
148: if (fail && key != NULL)
1.46 ! djm 149: sshkey_free(key);
1.1 markus 150: else
151: *ret = key;
152:
153: return (fail ? -1 : 0);
154: }
155:
156: int
157: main(int argc, char **argv)
158: {
1.46 ! djm 159: struct sshbuf *b;
1.7 markus 160: Options options;
1.39 markus 161: #define NUM_KEYTYPES 4
1.46 ! djm 162: struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
1.1 markus 163: struct passwd *pw;
1.45 djm 164: int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
1.46 ! djm 165: u_char *signature, *data, rver;
1.40 djm 166: char *host, *fp;
1.46 ! djm 167: size_t slen, dlen;
1.19 djm 168:
169: /* Ensure that stdin and stdout are connected */
170: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
171: exit(1);
172: /* Leave /dev/null fd iff it is attached to stderr */
173: if (fd > 2)
174: close(fd);
1.1 markus 175:
1.36 djm 176: i = 0;
177: key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
178: key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
1.39 markus 179: key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
1.36 djm 180: key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
1.1 markus 181:
1.18 dtucker 182: original_real_uid = getuid(); /* XXX readconf.c needs this */
183: if ((pw = getpwuid(original_real_uid)) == NULL)
1.17 dtucker 184: fatal("getpwuid failed");
185: pw = pwcopy(pw);
186:
187: permanently_set_uid(pw);
1.1 markus 188:
189: #ifdef DEBUG_SSH_KEYSIGN
190: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 191: #endif
1.7 markus 192:
193: /* verify that ssh-keysign is enabled by the admin */
194: initialize_options(&options);
1.43 djm 195: (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "", &options, 0);
1.7 markus 196: fill_default_options(&options);
1.8 markus 197: if (options.enable_ssh_keysign != 1)
198: fatal("ssh-keysign not enabled in %s",
1.7 markus 199: _PATH_HOST_CONFIG_FILE);
1.1 markus 200:
1.36 djm 201: for (i = found = 0; i < NUM_KEYTYPES; i++) {
202: if (key_fd[i] != -1)
203: found = 1;
204: }
205: if (found == 0)
1.1 markus 206: fatal("could not open any host key");
207:
1.35 djm 208: OpenSSL_add_all_algorithms();
1.1 markus 209:
210: found = 0;
1.36 djm 211: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 212: keys[i] = NULL;
213: if (key_fd[i] == -1)
214: continue;
1.45 djm 215: r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
216: NULL, &key, NULL);
1.1 markus 217: close(key_fd[i]);
1.45 djm 218: if (r != 0)
219: debug("parse key %d: %s", i, ssh_err(r));
220: else if (key != NULL) {
221: keys[i] = key;
1.1 markus 222: found = 1;
1.45 djm 223: }
1.1 markus 224: }
225: if (!found)
226: fatal("no hostkey found");
227:
1.46 ! djm 228: if ((b = sshbuf_new()) == NULL)
! 229: fatal("%s: sshbuf_new failed", __func__);
! 230: if (ssh_msg_recv(STDIN_FILENO, b) < 0)
1.9 djm 231: fatal("ssh_msg_recv failed");
1.46 ! djm 232: if ((r = sshbuf_get_u8(b, &rver)) != 0)
! 233: fatal("%s: buffer error: %s", __func__, ssh_err(r));
! 234: if (rver != version)
! 235: fatal("bad version: received %d, expected %d", rver, version);
! 236: if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
! 237: fatal("%s: buffer error: %s", __func__, ssh_err(r));
! 238: if (fd < 0 || fd == STDIN_FILENO || fd == STDOUT_FILENO)
1.2 markus 239: fatal("bad fd");
240: if ((host = get_local_name(fd)) == NULL)
1.30 dtucker 241: fatal("cannot get local name for fd");
1.4 deraadt 242:
1.46 ! djm 243: if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
! 244: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.2 markus 245: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 246: fatal("not a valid request");
1.37 djm 247: free(host);
1.1 markus 248:
249: found = 0;
1.36 djm 250: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 251: if (keys[i] != NULL &&
1.46 ! djm 252: sshkey_equal_public(key, keys[i])) {
1.1 markus 253: found = 1;
254: break;
255: }
256: }
1.40 djm 257: if (!found) {
1.46 ! djm 258: fp = sshkey_fingerprint(key, options.fingerprint_hash,
1.44 djm 259: SSH_FP_DEFAULT);
1.40 djm 260: fatal("no matching hostkey found for key %s %s",
1.46 ! djm 261: sshkey_type(key), fp ? fp : "");
1.40 djm 262: }
1.1 markus 263:
1.46 ! djm 264: if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, 0)) != 0)
! 265: fatal("sshkey_sign failed: %s", ssh_err(r));
1.37 djm 266: free(data);
1.4 deraadt 267:
1.1 markus 268: /* send reply */
1.46 ! djm 269: sshbuf_reset(b);
! 270: if ((r = sshbuf_put_string(b, signature, slen)) != 0)
! 271: fatal("%s: buffer error: %s", __func__, ssh_err(r));
! 272: if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
1.14 djm 273: fatal("ssh_msg_send failed");
1.1 markus 274:
275: return (0);
276: }
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