1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.17 2019/01/23 02:01:10 djm Exp $ */ 2 /* 3 * Copyright (c) 2010 Markus Friedl. All rights reserved. 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/types.h> 19 #include <sys/queue.h> 20 #include <sys/time.h> 21 22 #include <errno.h> 23 #include <poll.h> 24 #include <stdarg.h> 25 #include <string.h> 26 #include <unistd.h> 27 28 #include "xmalloc.h" 29 #include "sshbuf.h" 30 #include "log.h" 31 #include "misc.h" 32 #include "sshkey.h" 33 #include "authfd.h" 34 #include "ssh-pkcs11.h" 35 #include "ssherr.h" 36 37 /* borrows code from sftp-server and ssh-agent */ 38 39 struct pkcs11_keyinfo { 40 struct sshkey *key; 41 char *providername; 42 TAILQ_ENTRY(pkcs11_keyinfo) next; 43 }; 44 45 TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist; 46 47 #define MAX_MSG_LENGTH 10240 /*XXX*/ 48 49 /* input and output queue */ 50 struct sshbuf *iqueue; 51 struct sshbuf *oqueue; 52 53 static void 54 add_key(struct sshkey *k, char *name) 55 { 56 struct pkcs11_keyinfo *ki; 57 58 ki = xcalloc(1, sizeof(*ki)); 59 ki->providername = xstrdup(name); 60 ki->key = k; 61 TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next); 62 } 63 64 static void 65 del_keys_by_name(char *name) 66 { 67 struct pkcs11_keyinfo *ki, *nxt; 68 69 for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) { 70 nxt = TAILQ_NEXT(ki, next); 71 if (!strcmp(ki->providername, name)) { 72 TAILQ_REMOVE(&pkcs11_keylist, ki, next); 73 free(ki->providername); 74 sshkey_free(ki->key); 75 free(ki); 76 } 77 } 78 } 79 80 /* lookup matching 'private' key */ 81 static struct sshkey * 82 lookup_key(struct sshkey *k) 83 { 84 struct pkcs11_keyinfo *ki; 85 86 TAILQ_FOREACH(ki, &pkcs11_keylist, next) { 87 debug("check %p %s", ki, ki->providername); 88 if (sshkey_equal(k, ki->key)) 89 return (ki->key); 90 } 91 return (NULL); 92 } 93 94 static void 95 send_msg(struct sshbuf *m) 96 { 97 int r; 98 99 if ((r = sshbuf_put_stringb(oqueue, m)) != 0) 100 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 101 } 102 103 static void 104 process_add(void) 105 { 106 char *name, *pin; 107 struct sshkey **keys = NULL; 108 int r, i, nkeys; 109 u_char *blob; 110 size_t blen; 111 struct sshbuf *msg; 112 113 if ((msg = sshbuf_new()) == NULL) 114 fatal("%s: sshbuf_new failed", __func__); 115 if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 || 116 (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0) 117 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 118 if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) { 119 if ((r = sshbuf_put_u8(msg, 120 SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 121 (r = sshbuf_put_u32(msg, nkeys)) != 0) 122 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 123 for (i = 0; i < nkeys; i++) { 124 if ((r = sshkey_to_blob(keys[i], &blob, &blen)) != 0) { 125 debug("%s: sshkey_to_blob: %s", 126 __func__, ssh_err(r)); 127 continue; 128 } 129 if ((r = sshbuf_put_string(msg, blob, blen)) != 0 || 130 (r = sshbuf_put_cstring(msg, name)) != 0) 131 fatal("%s: buffer error: %s", 132 __func__, ssh_err(r)); 133 free(blob); 134 add_key(keys[i], name); 135 } 136 } else { 137 if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 138 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 139 if ((r = sshbuf_put_u32(msg, -nkeys)) != 0) 140 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 141 } 142 free(keys); 143 free(pin); 144 free(name); 145 send_msg(msg); 146 sshbuf_free(msg); 147 } 148 149 static void 150 process_del(void) 151 { 152 char *name, *pin; 153 struct sshbuf *msg; 154 int r; 155 156 if ((msg = sshbuf_new()) == NULL) 157 fatal("%s: sshbuf_new failed", __func__); 158 if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 || 159 (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0) 160 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 161 del_keys_by_name(name); 162 if ((r = sshbuf_put_u8(msg, pkcs11_del_provider(name) == 0 ? 163 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 164 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 165 free(pin); 166 free(name); 167 send_msg(msg); 168 sshbuf_free(msg); 169 } 170 171 static void 172 process_sign(void) 173 { 174 u_char *blob, *data, *signature = NULL; 175 size_t blen, dlen, slen = 0; 176 int r, ok = -1; 177 struct sshkey *key, *found; 178 struct sshbuf *msg; 179 180 /* XXX support SHA2 signature flags */ 181 if ((r = sshbuf_get_string(iqueue, &blob, &blen)) != 0 || 182 (r = sshbuf_get_string(iqueue, &data, &dlen)) != 0 || 183 (r = sshbuf_get_u32(iqueue, NULL)) != 0) 184 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 185 186 if ((r = sshkey_from_blob(blob, blen, &key)) != 0) 187 error("%s: sshkey_from_blob: %s", __func__, ssh_err(r)); 188 else { 189 if ((found = lookup_key(key)) != NULL) { 190 #ifdef WITH_OPENSSL 191 u_int xslen; 192 int ret; 193 194 if (key->type == KEY_RSA) { 195 slen = RSA_size(key->rsa); 196 signature = xmalloc(slen); 197 ret = RSA_private_encrypt(dlen, data, signature, 198 found->rsa, RSA_PKCS1_PADDING); 199 if (ret != -1) { 200 slen = ret; 201 ok = 0; 202 } 203 } else if (key->type == KEY_ECDSA) { 204 xslen = ECDSA_size(key->ecdsa); 205 signature = xmalloc(xslen); 206 /* "The parameter type is ignored." */ 207 ret = ECDSA_sign(-1, data, dlen, signature, 208 &xslen, found->ecdsa); 209 if (ret != 0) 210 ok = 0; 211 else 212 error("%s: ECDSA_sign" 213 " returns %d", __func__, ret); 214 slen = xslen; 215 } else 216 error("%s: don't know how to sign with key " 217 "type %d", __func__, (int)key->type); 218 #endif /* WITH_OPENSSL */ 219 } 220 sshkey_free(key); 221 } 222 if ((msg = sshbuf_new()) == NULL) 223 fatal("%s: sshbuf_new failed", __func__); 224 if (ok == 0) { 225 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 226 (r = sshbuf_put_string(msg, signature, slen)) != 0) 227 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 228 } else { 229 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_FAILURE)) != 0) 230 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 231 } 232 free(data); 233 free(blob); 234 free(signature); 235 send_msg(msg); 236 sshbuf_free(msg); 237 } 238 239 static void 240 process(void) 241 { 242 u_int msg_len; 243 u_int buf_len; 244 u_int consumed; 245 u_char type; 246 const u_char *cp; 247 int r; 248 249 buf_len = sshbuf_len(iqueue); 250 if (buf_len < 5) 251 return; /* Incomplete message. */ 252 cp = sshbuf_ptr(iqueue); 253 msg_len = get_u32(cp); 254 if (msg_len > MAX_MSG_LENGTH) { 255 error("bad message len %d", msg_len); 256 cleanup_exit(11); 257 } 258 if (buf_len < msg_len + 4) 259 return; 260 if ((r = sshbuf_consume(iqueue, 4)) != 0 || 261 (r = sshbuf_get_u8(iqueue, &type)) != 0) 262 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 263 buf_len -= 4; 264 switch (type) { 265 case SSH_AGENTC_ADD_SMARTCARD_KEY: 266 debug("process_add"); 267 process_add(); 268 break; 269 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 270 debug("process_del"); 271 process_del(); 272 break; 273 case SSH2_AGENTC_SIGN_REQUEST: 274 debug("process_sign"); 275 process_sign(); 276 break; 277 default: 278 error("Unknown message %d", type); 279 break; 280 } 281 /* discard the remaining bytes from the current packet */ 282 if (buf_len < sshbuf_len(iqueue)) { 283 error("iqueue grew unexpectedly"); 284 cleanup_exit(255); 285 } 286 consumed = buf_len - sshbuf_len(iqueue); 287 if (msg_len < consumed) { 288 error("msg_len %d < consumed %d", msg_len, consumed); 289 cleanup_exit(255); 290 } 291 if (msg_len > consumed) { 292 if ((r = sshbuf_consume(iqueue, msg_len - consumed)) != 0) 293 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 294 } 295 } 296 297 void 298 cleanup_exit(int i) 299 { 300 /* XXX */ 301 _exit(i); 302 } 303 304 305 int 306 main(int argc, char **argv) 307 { 308 int r, ch, in, out, max, log_stderr = 0; 309 ssize_t len; 310 SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; 311 LogLevel log_level = SYSLOG_LEVEL_ERROR; 312 char buf[4*4096]; 313 extern char *__progname; 314 struct pollfd pfd[2]; 315 316 ssh_malloc_init(); /* must be called before any mallocs */ 317 TAILQ_INIT(&pkcs11_keylist); 318 319 log_init(__progname, log_level, log_facility, log_stderr); 320 321 while ((ch = getopt(argc, argv, "v")) != -1) { 322 switch (ch) { 323 case 'v': 324 log_stderr = 1; 325 if (log_level == SYSLOG_LEVEL_ERROR) 326 log_level = SYSLOG_LEVEL_DEBUG1; 327 else if (log_level < SYSLOG_LEVEL_DEBUG3) 328 log_level++; 329 break; 330 default: 331 fprintf(stderr, "usage: %s [-v]\n", __progname); 332 exit(1); 333 } 334 } 335 336 log_init(__progname, log_level, log_facility, log_stderr); 337 338 pkcs11_init(0); 339 in = STDIN_FILENO; 340 out = STDOUT_FILENO; 341 342 max = 0; 343 if (in > max) 344 max = in; 345 if (out > max) 346 max = out; 347 348 if ((iqueue = sshbuf_new()) == NULL) 349 fatal("%s: sshbuf_new failed", __func__); 350 if ((oqueue = sshbuf_new()) == NULL) 351 fatal("%s: sshbuf_new failed", __func__); 352 353 while (1) { 354 memset(pfd, 0, sizeof(pfd)); 355 pfd[0].fd = in; 356 pfd[1].fd = out; 357 358 /* 359 * Ensure that we can read a full buffer and handle 360 * the worst-case length packet it can generate, 361 * otherwise apply backpressure by stopping reads. 362 */ 363 if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 && 364 (r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0) 365 pfd[0].events = POLLIN; 366 else if (r != SSH_ERR_NO_BUFFER_SPACE) 367 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 368 369 if (sshbuf_len(oqueue) > 0) 370 pfd[1].events = POLLOUT; 371 372 if ((r = poll(pfd, 2, -1 /* INFTIM */)) <= 0) { 373 if (r == 0 || errno == EINTR) 374 continue; 375 fatal("poll: %s", strerror(errno)); 376 } 377 378 /* copy stdin to iqueue */ 379 if ((pfd[0].revents & (POLLIN|POLLERR)) != 0) { 380 len = read(in, buf, sizeof buf); 381 if (len == 0) { 382 debug("read eof"); 383 cleanup_exit(0); 384 } else if (len < 0) { 385 error("read: %s", strerror(errno)); 386 cleanup_exit(1); 387 } else if ((r = sshbuf_put(iqueue, buf, len)) != 0) { 388 fatal("%s: buffer error: %s", 389 __func__, ssh_err(r)); 390 } 391 } 392 /* send oqueue to stdout */ 393 if ((pfd[1].revents & (POLLOUT|POLLHUP)) != 0) { 394 len = write(out, sshbuf_ptr(oqueue), 395 sshbuf_len(oqueue)); 396 if (len < 0) { 397 error("write: %s", strerror(errno)); 398 cleanup_exit(1); 399 } else if ((r = sshbuf_consume(oqueue, len)) != 0) { 400 fatal("%s: buffer error: %s", 401 __func__, ssh_err(r)); 402 } 403 } 404 405 /* 406 * Process requests from client if we can fit the results 407 * into the output buffer, otherwise stop processing input 408 * and let the output queue drain. 409 */ 410 if ((r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0) 411 process(); 412 else if (r != SSH_ERR_NO_BUFFER_SPACE) 413 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 414 } 415 } 416