Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.59
1.59 ! djm 1: /* $OpenBSD: ssh-keysign.c,v 1.58 2019/06/14 03:28:19 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>
1.59 ! djm 35: #include <stdio.h>
1.27 stevesk 36: #include <string.h>
1.26 stevesk 37: #include <unistd.h>
1.50 djm 38: #include <errno.h>
1.1 markus 39:
1.29 deraadt 40: #include "xmalloc.h"
1.1 markus 41: #include "log.h"
1.46 djm 42: #include "sshkey.h"
1.7 markus 43: #include "ssh.h"
1.1 markus 44: #include "ssh2.h"
45: #include "misc.h"
1.46 djm 46: #include "sshbuf.h"
1.1 markus 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"
1.45 djm 53: #include "sshkey.h"
54: #include "ssherr.h"
1.7 markus 55:
1.50 djm 56: extern char *__progname;
57:
1.1 markus 58: static int
1.46 djm 59: valid_request(struct passwd *pw, char *host, struct sshkey **ret,
60: u_char *data, size_t datalen)
1.1 markus 61: {
1.46 djm 62: struct sshbuf *b;
63: struct sshkey *key = NULL;
64: u_char type, *pkblob;
65: char *p;
66: size_t blen, len;
67: char *pkalg, *luser;
68: int r, pktype, fail;
1.1 markus 69:
1.45 djm 70: if (ret != NULL)
71: *ret = NULL;
1.1 markus 72: fail = 0;
73:
1.46 djm 74: if ((b = sshbuf_from(data, datalen)) == NULL)
75: fatal("%s: sshbuf_from failed", __func__);
1.4 deraadt 76:
1.23 dtucker 77: /* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
1.46 djm 78: if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
79: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.23 dtucker 80: if (len != 20 && len != 32)
1.3 markus 81: fail++;
82:
1.46 djm 83: if ((r = sshbuf_get_u8(b, &type)) != 0)
84: fatal("%s: buffer error: %s", __func__, ssh_err(r));
85: if (type != SSH2_MSG_USERAUTH_REQUEST)
1.1 markus 86: fail++;
87:
88: /* server user */
1.46 djm 89: if ((r = sshbuf_skip_string(b)) != 0)
90: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 91:
92: /* service */
1.46 djm 93: if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
94: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 95: if (strcmp("ssh-connection", p) != 0)
96: fail++;
1.37 djm 97: free(p);
1.1 markus 98:
99: /* method */
1.46 djm 100: if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
101: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 102: if (strcmp("hostbased", p) != 0)
103: fail++;
1.37 djm 104: free(p);
1.1 markus 105:
106: /* pubkey */
1.46 djm 107: if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
108: (r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
109: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.1 markus 110:
1.46 djm 111: pktype = sshkey_type_from_name(pkalg);
1.1 markus 112: if (pktype == KEY_UNSPEC)
113: fail++;
1.46 djm 114: else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
115: error("%s: bad key blob: %s", __func__, ssh_err(r));
1.1 markus 116: fail++;
1.46 djm 117: } else if (key->type != pktype)
1.1 markus 118: fail++;
1.37 djm 119: free(pkalg);
120: free(pkblob);
1.1 markus 121:
1.2 markus 122: /* client host name, handle trailing dot */
1.46 djm 123: if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
124: fatal("%s: buffer error: %s", __func__, ssh_err(r));
125: debug2("%s: check expect chost %s got %s", __func__, host, p);
1.2 markus 126: if (strlen(host) != len - 1)
127: fail++;
128: else if (p[len - 1] != '.')
1.4 deraadt 129: fail++;
1.2 markus 130: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 131: fail++;
1.37 djm 132: free(p);
1.1 markus 133:
134: /* local user */
1.46 djm 135: if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
136: fatal("%s: buffer error: %s", __func__, ssh_err(r));
1.2 markus 137:
1.46 djm 138: if (strcmp(pw->pw_name, luser) != 0)
1.1 markus 139: fail++;
1.46 djm 140: free(luser);
1.1 markus 141:
142: /* end of message */
1.46 djm 143: if (sshbuf_len(b) != 0)
1.1 markus 144: fail++;
1.46 djm 145: sshbuf_free(b);
1.1 markus 146:
1.46 djm 147: debug3("%s: fail %d", __func__, fail);
1.1 markus 148:
1.53 dtucker 149: if (fail)
1.46 djm 150: sshkey_free(key);
1.48 markus 151: else if (ret != NULL)
1.1 markus 152: *ret = key;
153:
154: return (fail ? -1 : 0);
155: }
156:
157: int
158: main(int argc, char **argv)
159: {
1.46 djm 160: struct sshbuf *b;
1.7 markus 161: Options options;
1.54 markus 162: #define NUM_KEYTYPES 5
1.46 djm 163: struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
1.1 markus 164: struct passwd *pw;
1.45 djm 165: int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
1.46 djm 166: u_char *signature, *data, rver;
1.40 djm 167: char *host, *fp;
1.46 djm 168: size_t slen, dlen;
1.19 djm 169:
1.50 djm 170: if (pledge("stdio rpath getpw dns id", NULL) != 0)
171: fatal("%s: pledge: %s", __progname, strerror(errno));
172:
1.19 djm 173: /* Ensure that stdin and stdout are connected */
174: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
175: exit(1);
176: /* Leave /dev/null fd iff it is attached to stderr */
177: if (fd > 2)
178: close(fd);
1.1 markus 179:
1.36 djm 180: i = 0;
1.49 djm 181: /* XXX This really needs to read sshd_config for the paths */
1.36 djm 182: key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
183: key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
1.39 markus 184: key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
1.54 markus 185: key_fd[i++] = open(_PATH_HOST_XMSS_KEY_FILE, O_RDONLY);
1.36 djm 186: key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
1.1 markus 187:
1.55 dtucker 188: if ((pw = getpwuid(getuid())) == NULL)
1.17 dtucker 189: fatal("getpwuid failed");
190: pw = pwcopy(pw);
191:
192: permanently_set_uid(pw);
1.1 markus 193:
194: #ifdef DEBUG_SSH_KEYSIGN
195: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 196: #endif
1.7 markus 197:
198: /* verify that ssh-keysign is enabled by the admin */
199: initialize_options(&options);
1.56 djm 200: (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "",
201: &options, 0, NULL);
1.7 markus 202: fill_default_options(&options);
1.8 markus 203: if (options.enable_ssh_keysign != 1)
204: fatal("ssh-keysign not enabled in %s",
1.7 markus 205: _PATH_HOST_CONFIG_FILE);
1.1 markus 206:
1.36 djm 207: for (i = found = 0; i < NUM_KEYTYPES; i++) {
208: if (key_fd[i] != -1)
209: found = 1;
210: }
211: if (found == 0)
1.1 markus 212: fatal("could not open any host key");
213:
1.35 djm 214: OpenSSL_add_all_algorithms();
1.1 markus 215:
216: found = 0;
1.36 djm 217: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 218: keys[i] = NULL;
219: if (key_fd[i] == -1)
220: continue;
1.45 djm 221: r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
222: NULL, &key, NULL);
1.1 markus 223: close(key_fd[i]);
1.45 djm 224: if (r != 0)
225: debug("parse key %d: %s", i, ssh_err(r));
226: else if (key != NULL) {
227: keys[i] = key;
1.1 markus 228: found = 1;
1.45 djm 229: }
1.1 markus 230: }
231: if (!found)
232: fatal("no hostkey found");
233:
1.50 djm 234: if (pledge("stdio dns", NULL) != 0)
235: fatal("%s: pledge: %s", __progname, strerror(errno));
236:
1.46 djm 237: if ((b = sshbuf_new()) == NULL)
1.50 djm 238: fatal("%s: sshbuf_new failed", __progname);
1.46 djm 239: if (ssh_msg_recv(STDIN_FILENO, b) < 0)
1.9 djm 240: fatal("ssh_msg_recv failed");
1.46 djm 241: if ((r = sshbuf_get_u8(b, &rver)) != 0)
1.50 djm 242: fatal("%s: buffer error: %s", __progname, ssh_err(r));
1.46 djm 243: if (rver != version)
244: fatal("bad version: received %d, expected %d", rver, version);
245: if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
1.50 djm 246: fatal("%s: buffer error: %s", __progname, ssh_err(r));
1.46 djm 247: if (fd < 0 || fd == STDIN_FILENO || fd == STDOUT_FILENO)
1.58 djm 248: fatal("bad fd = %d", fd);
1.2 markus 249: if ((host = get_local_name(fd)) == NULL)
1.30 dtucker 250: fatal("cannot get local name for fd");
1.4 deraadt 251:
1.46 djm 252: if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
1.50 djm 253: fatal("%s: buffer error: %s", __progname, ssh_err(r));
1.2 markus 254: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 255: fatal("not a valid request");
1.37 djm 256: free(host);
1.1 markus 257:
258: found = 0;
1.36 djm 259: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 260: if (keys[i] != NULL &&
1.46 djm 261: sshkey_equal_public(key, keys[i])) {
1.1 markus 262: found = 1;
263: break;
264: }
265: }
1.40 djm 266: if (!found) {
1.47 djm 267: if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
268: SSH_FP_DEFAULT)) == NULL)
1.50 djm 269: fatal("%s: sshkey_fingerprint failed", __progname);
1.40 djm 270: fatal("no matching hostkey found for key %s %s",
1.46 djm 271: sshkey_type(key), fp ? fp : "");
1.40 djm 272: }
1.1 markus 273:
1.51 markus 274: if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, NULL, 0))
275: != 0)
1.46 djm 276: fatal("sshkey_sign failed: %s", ssh_err(r));
1.37 djm 277: free(data);
1.4 deraadt 278:
1.1 markus 279: /* send reply */
1.46 djm 280: sshbuf_reset(b);
281: if ((r = sshbuf_put_string(b, signature, slen)) != 0)
1.50 djm 282: fatal("%s: buffer error: %s", __progname, ssh_err(r));
1.46 djm 283: if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
1.14 djm 284: fatal("ssh_msg_send failed");
1.1 markus 285:
286: return (0);
287: }
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh-keysign.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh