Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.74
1.74 ! djm 1: /* $OpenBSD: ssh-keysign.c,v 1.73 2024/01/11 01:51:16 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:
1.60 djm 28: #ifdef WITH_OPENSSL
1.1 markus 29: #include <openssl/evp.h>
1.60 djm 30: #endif
1.24 stevesk 31:
1.25 stevesk 32: #include <fcntl.h>
1.24 stevesk 33: #include <paths.h>
34: #include <pwd.h>
1.67 dtucker 35: #include <stdarg.h>
36: #include <stdio.h>
1.28 stevesk 37: #include <stdlib.h>
1.27 stevesk 38: #include <string.h>
1.26 stevesk 39: #include <unistd.h>
1.50 djm 40: #include <errno.h>
1.1 markus 41:
1.29 deraadt 42: #include "xmalloc.h"
1.1 markus 43: #include "log.h"
1.46 djm 44: #include "sshkey.h"
1.7 markus 45: #include "ssh.h"
1.1 markus 46: #include "ssh2.h"
47: #include "misc.h"
1.46 djm 48: #include "sshbuf.h"
1.1 markus 49: #include "authfile.h"
50: #include "msg.h"
1.2 markus 51: #include "canohost.h"
1.1 markus 52: #include "pathnames.h"
1.7 markus 53: #include "readconf.h"
1.17 dtucker 54: #include "uidswap.h"
1.45 djm 55: #include "ssherr.h"
1.7 markus 56:
1.50 djm 57: extern char *__progname;
58:
1.1 markus 59: static int
1.70 djm 60: valid_request(struct passwd *pw, char *host, struct sshkey **ret, char **pkalgp,
1.46 djm 61: u_char *data, size_t datalen)
1.1 markus 62: {
1.46 djm 63: struct sshbuf *b;
64: struct sshkey *key = NULL;
65: u_char type, *pkblob;
66: char *p;
67: size_t blen, len;
68: char *pkalg, *luser;
69: int r, pktype, fail;
1.1 markus 70:
1.45 djm 71: if (ret != NULL)
72: *ret = NULL;
1.70 djm 73: if (pkalgp != NULL)
74: *pkalgp = NULL;
1.1 markus 75: fail = 0;
76:
1.46 djm 77: if ((b = sshbuf_from(data, datalen)) == NULL)
1.65 djm 78: fatal_f("sshbuf_from failed");
1.4 deraadt 79:
1.68 djm 80: /* session id */
1.46 djm 81: if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
1.65 djm 82: fatal_fr(r, "parse session ID");
1.68 djm 83: if (len != 20 && /* SHA1 */
84: len != 32 && /* SHA256 */
85: len != 48 && /* SHA384 */
86: len != 64) /* SHA512 */
1.3 markus 87: fail++;
88:
1.46 djm 89: if ((r = sshbuf_get_u8(b, &type)) != 0)
1.65 djm 90: fatal_fr(r, "parse type");
1.46 djm 91: if (type != SSH2_MSG_USERAUTH_REQUEST)
1.1 markus 92: fail++;
93:
94: /* server user */
1.46 djm 95: if ((r = sshbuf_skip_string(b)) != 0)
1.65 djm 96: fatal_fr(r, "parse user");
1.1 markus 97:
98: /* service */
1.46 djm 99: if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
1.65 djm 100: fatal_fr(r, "parse service");
1.1 markus 101: if (strcmp("ssh-connection", p) != 0)
102: fail++;
1.37 djm 103: free(p);
1.1 markus 104:
105: /* method */
1.46 djm 106: if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
1.65 djm 107: fatal_fr(r, "parse method");
1.1 markus 108: if (strcmp("hostbased", p) != 0)
109: fail++;
1.37 djm 110: free(p);
1.1 markus 111:
112: /* pubkey */
1.46 djm 113: if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
114: (r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
1.65 djm 115: fatal_fr(r, "parse pk");
1.1 markus 116:
1.46 djm 117: pktype = sshkey_type_from_name(pkalg);
1.1 markus 118: if (pktype == KEY_UNSPEC)
119: fail++;
1.46 djm 120: else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
1.65 djm 121: error_fr(r, "decode key");
1.1 markus 122: fail++;
1.46 djm 123: } else if (key->type != pktype)
1.1 markus 124: fail++;
125:
1.2 markus 126: /* client host name, handle trailing dot */
1.46 djm 127: if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
1.65 djm 128: fatal_fr(r, "parse hostname");
129: debug2_f("check expect chost %s got %s", host, p);
1.2 markus 130: if (strlen(host) != len - 1)
131: fail++;
132: else if (p[len - 1] != '.')
1.4 deraadt 133: fail++;
1.2 markus 134: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 135: fail++;
1.37 djm 136: free(p);
1.1 markus 137:
138: /* local user */
1.46 djm 139: if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
1.65 djm 140: fatal_fr(r, "parse luser");
1.2 markus 141:
1.46 djm 142: if (strcmp(pw->pw_name, luser) != 0)
1.1 markus 143: fail++;
1.46 djm 144: free(luser);
1.1 markus 145:
146: /* end of message */
1.46 djm 147: if (sshbuf_len(b) != 0)
1.1 markus 148: fail++;
1.46 djm 149: sshbuf_free(b);
1.1 markus 150:
1.65 djm 151: debug3_f("fail %d", fail);
1.1 markus 152:
1.71 djm 153: if (!fail) {
1.70 djm 154: if (ret != NULL) {
155: *ret = key;
156: key = NULL;
157: }
158: if (pkalgp != NULL) {
159: *pkalgp = pkalg;
160: pkalg = NULL;
161: }
162: }
163: sshkey_free(key);
164: free(pkalg);
165: free(pkblob);
1.1 markus 166:
167: return (fail ? -1 : 0);
168: }
169:
170: int
171: main(int argc, char **argv)
172: {
1.46 djm 173: struct sshbuf *b;
1.7 markus 174: Options options;
1.54 markus 175: #define NUM_KEYTYPES 5
1.46 djm 176: struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
1.1 markus 177: struct passwd *pw;
1.45 djm 178: int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
1.46 djm 179: u_char *signature, *data, rver;
1.70 djm 180: char *host, *fp, *pkalg;
1.46 djm 181: size_t slen, dlen;
1.19 djm 182:
1.50 djm 183: if (pledge("stdio rpath getpw dns id", NULL) != 0)
184: fatal("%s: pledge: %s", __progname, strerror(errno));
185:
1.19 djm 186: /* Ensure that stdin and stdout are connected */
187: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
188: exit(1);
189: /* Leave /dev/null fd iff it is attached to stderr */
190: if (fd > 2)
191: close(fd);
1.73 djm 192:
193: for (i = 0; i < NUM_KEYTYPES; i++)
194: key_fd[i] = -1;
1.1 markus 195:
1.36 djm 196: i = 0;
1.49 djm 197: /* XXX This really needs to read sshd_config for the paths */
1.72 djm 198: #ifdef WITH_DSA
1.36 djm 199: key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
1.72 djm 200: #endif
1.36 djm 201: key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
1.39 markus 202: key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
1.54 markus 203: key_fd[i++] = open(_PATH_HOST_XMSS_KEY_FILE, O_RDONLY);
1.36 djm 204: key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
1.1 markus 205:
1.55 dtucker 206: if ((pw = getpwuid(getuid())) == NULL)
1.17 dtucker 207: fatal("getpwuid failed");
208: pw = pwcopy(pw);
209:
210: permanently_set_uid(pw);
1.1 markus 211:
212: #ifdef DEBUG_SSH_KEYSIGN
213: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 214: #endif
1.7 markus 215:
216: /* verify that ssh-keysign is enabled by the admin */
217: initialize_options(&options);
1.56 djm 218: (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "",
219: &options, 0, NULL);
1.66 djm 220: (void)fill_default_options(&options);
1.8 markus 221: if (options.enable_ssh_keysign != 1)
222: fatal("ssh-keysign not enabled in %s",
1.7 markus 223: _PATH_HOST_CONFIG_FILE);
1.1 markus 224:
1.69 deraadt 225: if (pledge("stdio dns", NULL) != 0)
226: fatal("%s: pledge: %s", __progname, strerror(errno));
227:
1.36 djm 228: for (i = found = 0; i < NUM_KEYTYPES; i++) {
229: if (key_fd[i] != -1)
230: found = 1;
231: }
232: if (found == 0)
1.1 markus 233: fatal("could not open any host key");
234:
1.60 djm 235: #ifdef WITH_OPENSSL
1.35 djm 236: OpenSSL_add_all_algorithms();
1.60 djm 237: #endif
1.69 deraadt 238:
1.1 markus 239: found = 0;
1.36 djm 240: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 241: keys[i] = NULL;
242: if (key_fd[i] == -1)
243: continue;
1.45 djm 244: r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
245: NULL, &key, NULL);
1.1 markus 246: close(key_fd[i]);
1.45 djm 247: if (r != 0)
1.65 djm 248: debug_r(r, "parse key %d", i);
1.45 djm 249: else if (key != NULL) {
250: keys[i] = key;
1.1 markus 251: found = 1;
1.45 djm 252: }
1.1 markus 253: }
254: if (!found)
255: fatal("no hostkey found");
1.50 djm 256:
1.46 djm 257: if ((b = sshbuf_new()) == NULL)
1.50 djm 258: fatal("%s: sshbuf_new failed", __progname);
1.46 djm 259: if (ssh_msg_recv(STDIN_FILENO, b) < 0)
1.65 djm 260: fatal("%s: ssh_msg_recv failed", __progname);
1.46 djm 261: if ((r = sshbuf_get_u8(b, &rver)) != 0)
1.65 djm 262: fatal_r(r, "%s: buffer error", __progname);
1.46 djm 263: if (rver != version)
1.65 djm 264: fatal("%s: bad version: received %d, expected %d",
265: __progname, rver, version);
1.46 djm 266: if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
1.65 djm 267: fatal_r(r, "%s: buffer error", __progname);
1.74 ! djm 268: if (fd <= STDERR_FILENO)
1.65 djm 269: fatal("%s: bad fd = %d", __progname, fd);
1.2 markus 270: if ((host = get_local_name(fd)) == NULL)
1.65 djm 271: fatal("%s: cannot get local name for fd", __progname);
1.4 deraadt 272:
1.46 djm 273: if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
1.65 djm 274: fatal_r(r, "%s: buffer error", __progname);
1.70 djm 275: if (valid_request(pw, host, &key, &pkalg, data, dlen) < 0)
1.65 djm 276: fatal("%s: not a valid request", __progname);
1.37 djm 277: free(host);
1.1 markus 278:
279: found = 0;
1.36 djm 280: for (i = 0; i < NUM_KEYTYPES; i++) {
1.1 markus 281: if (keys[i] != NULL &&
1.46 djm 282: sshkey_equal_public(key, keys[i])) {
1.1 markus 283: found = 1;
284: break;
285: }
286: }
1.40 djm 287: if (!found) {
1.47 djm 288: if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
289: SSH_FP_DEFAULT)) == NULL)
1.50 djm 290: fatal("%s: sshkey_fingerprint failed", __progname);
1.65 djm 291: fatal("%s: no matching hostkey found for key %s %s", __progname,
1.46 djm 292: sshkey_type(key), fp ? fp : "");
1.40 djm 293: }
1.1 markus 294:
1.62 djm 295: if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen,
1.70 djm 296: pkalg, NULL, NULL, 0)) != 0)
1.65 djm 297: fatal_r(r, "%s: sshkey_sign failed", __progname);
1.37 djm 298: free(data);
1.4 deraadt 299:
1.1 markus 300: /* send reply */
1.46 djm 301: sshbuf_reset(b);
302: if ((r = sshbuf_put_string(b, signature, slen)) != 0)
1.65 djm 303: fatal_r(r, "%s: buffer error", __progname);
1.46 djm 304: if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
1.65 djm 305: fatal("%s: ssh_msg_send failed", __progname);
1.1 markus 306:
307: return (0);
308: }
![[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