1 /* $OpenBSD: ssh-agent.c,v 1.221 2017/04/30 23:29:10 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include <sys/types.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 #include <sys/resource.h> 41 #include <sys/socket.h> 42 #include <sys/stat.h> 43 #include <sys/un.h> 44 45 #ifdef WITH_OPENSSL 46 #include <openssl/evp.h> 47 #endif 48 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <paths.h> 52 #include <signal.h> 53 #include <stdlib.h> 54 #include <stdio.h> 55 #include <string.h> 56 #include <limits.h> 57 #include <time.h> 58 #include <unistd.h> 59 #include <util.h> 60 61 #include "xmalloc.h" 62 #include "ssh.h" 63 #include "rsa.h" 64 #include "sshbuf.h" 65 #include "sshkey.h" 66 #include "authfd.h" 67 #include "compat.h" 68 #include "log.h" 69 #include "misc.h" 70 #include "digest.h" 71 #include "ssherr.h" 72 #include "match.h" 73 74 #ifdef ENABLE_PKCS11 75 #include "ssh-pkcs11.h" 76 #endif 77 78 #ifndef DEFAULT_PKCS11_WHITELIST 79 # define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" 80 #endif 81 82 typedef enum { 83 AUTH_UNUSED, 84 AUTH_SOCKET, 85 AUTH_CONNECTION 86 } sock_type; 87 88 typedef struct { 89 int fd; 90 sock_type type; 91 struct sshbuf *input; 92 struct sshbuf *output; 93 struct sshbuf *request; 94 } SocketEntry; 95 96 u_int sockets_alloc = 0; 97 SocketEntry *sockets = NULL; 98 99 typedef struct identity { 100 TAILQ_ENTRY(identity) next; 101 struct sshkey *key; 102 char *comment; 103 char *provider; 104 time_t death; 105 u_int confirm; 106 } Identity; 107 108 struct idtable { 109 int nentries; 110 TAILQ_HEAD(idqueue, identity) idlist; 111 }; 112 113 /* private key table */ 114 struct idtable *idtab; 115 116 int max_fd = 0; 117 118 /* pid of shell == parent of agent */ 119 pid_t parent_pid = -1; 120 time_t parent_alive_interval = 0; 121 122 /* pid of process for which cleanup_socket is applicable */ 123 pid_t cleanup_pid = 0; 124 125 /* pathname and directory for AUTH_SOCKET */ 126 char socket_name[PATH_MAX]; 127 char socket_dir[PATH_MAX]; 128 129 /* PKCS#11 path whitelist */ 130 static char *pkcs11_whitelist; 131 132 /* locking */ 133 #define LOCK_SIZE 32 134 #define LOCK_SALT_SIZE 16 135 #define LOCK_ROUNDS 1 136 int locked = 0; 137 u_char lock_pwhash[LOCK_SIZE]; 138 u_char lock_salt[LOCK_SALT_SIZE]; 139 140 extern char *__progname; 141 142 /* Default lifetime in seconds (0 == forever) */ 143 static long lifetime = 0; 144 145 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 146 147 static void 148 close_socket(SocketEntry *e) 149 { 150 close(e->fd); 151 e->fd = -1; 152 e->type = AUTH_UNUSED; 153 sshbuf_free(e->input); 154 sshbuf_free(e->output); 155 sshbuf_free(e->request); 156 } 157 158 static void 159 idtab_init(void) 160 { 161 idtab = xcalloc(1, sizeof(*idtab)); 162 TAILQ_INIT(&idtab->idlist); 163 idtab->nentries = 0; 164 } 165 166 static void 167 free_identity(Identity *id) 168 { 169 sshkey_free(id->key); 170 free(id->provider); 171 free(id->comment); 172 free(id); 173 } 174 175 /* return matching private key for given public key */ 176 static Identity * 177 lookup_identity(struct sshkey *key) 178 { 179 Identity *id; 180 181 TAILQ_FOREACH(id, &idtab->idlist, next) { 182 if (sshkey_equal(key, id->key)) 183 return (id); 184 } 185 return (NULL); 186 } 187 188 /* Check confirmation of keysign request */ 189 static int 190 confirm_key(Identity *id) 191 { 192 char *p; 193 int ret = -1; 194 195 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 196 if (p != NULL && 197 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 198 id->comment, p)) 199 ret = 0; 200 free(p); 201 202 return (ret); 203 } 204 205 static void 206 send_status(SocketEntry *e, int success) 207 { 208 int r; 209 210 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 211 (r = sshbuf_put_u8(e->output, success ? 212 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 213 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 214 } 215 216 /* send list of supported public keys to 'client' */ 217 static void 218 process_request_identities(SocketEntry *e) 219 { 220 Identity *id; 221 struct sshbuf *msg; 222 int r; 223 224 if ((msg = sshbuf_new()) == NULL) 225 fatal("%s: sshbuf_new failed", __func__); 226 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 227 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 228 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 229 TAILQ_FOREACH(id, &idtab->idlist, next) { 230 if ((r = sshkey_puts(id->key, msg)) != 0 || 231 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 232 error("%s: put key/comment: %s", __func__, 233 ssh_err(r)); 234 continue; 235 } 236 } 237 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 238 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 239 sshbuf_free(msg); 240 } 241 242 243 static char * 244 agent_decode_alg(struct sshkey *key, u_int flags) 245 { 246 if (key->type == KEY_RSA) { 247 if (flags & SSH_AGENT_RSA_SHA2_256) 248 return "rsa-sha2-256"; 249 else if (flags & SSH_AGENT_RSA_SHA2_512) 250 return "rsa-sha2-512"; 251 } 252 return NULL; 253 } 254 255 /* ssh2 only */ 256 static void 257 process_sign_request2(SocketEntry *e) 258 { 259 const u_char *data; 260 u_char *signature = NULL; 261 size_t dlen, slen = 0; 262 u_int compat = 0, flags; 263 int r, ok = -1; 264 struct sshbuf *msg; 265 struct sshkey *key = NULL; 266 struct identity *id; 267 268 if ((msg = sshbuf_new()) == NULL) 269 fatal("%s: sshbuf_new failed", __func__); 270 if ((r = sshkey_froms(e->request, &key)) != 0 || 271 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 272 (r = sshbuf_get_u32(e->request, &flags)) != 0) 273 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 274 if (flags & SSH_AGENT_OLD_SIGNATURE) 275 compat = SSH_BUG_SIGBLOB; 276 if ((id = lookup_identity(key)) == NULL) { 277 verbose("%s: %s key not found", __func__, sshkey_type(key)); 278 goto send; 279 } 280 if (id->confirm && confirm_key(id) != 0) { 281 verbose("%s: user refused key", __func__); 282 goto send; 283 } 284 if ((r = sshkey_sign(id->key, &signature, &slen, 285 data, dlen, agent_decode_alg(key, flags), compat)) != 0) { 286 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 287 goto send; 288 } 289 /* Success */ 290 ok = 0; 291 send: 292 sshkey_free(key); 293 if (ok == 0) { 294 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 295 (r = sshbuf_put_string(msg, signature, slen)) != 0) 296 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 297 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 298 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 299 300 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 301 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 302 303 sshbuf_free(msg); 304 free(signature); 305 } 306 307 /* shared */ 308 static void 309 process_remove_identity(SocketEntry *e) 310 { 311 int r, success = 0; 312 struct sshkey *key = NULL; 313 Identity *id; 314 315 if ((r = sshkey_froms(e->request, &key)) != 0) { 316 error("%s: get key: %s", __func__, ssh_err(r)); 317 goto done; 318 } 319 if ((id = lookup_identity(key)) == NULL) { 320 debug("%s: key not found", __func__); 321 goto done; 322 } 323 /* We have this key, free it. */ 324 if (idtab->nentries < 1) 325 fatal("%s: internal error: nentries %d", 326 __func__, idtab->nentries); 327 TAILQ_REMOVE(&idtab->idlist, id, next); 328 free_identity(id); 329 idtab->nentries--; 330 sshkey_free(key); 331 success = 1; 332 done: 333 send_status(e, success); 334 } 335 336 static void 337 process_remove_all_identities(SocketEntry *e) 338 { 339 Identity *id; 340 341 /* Loop over all identities and clear the keys. */ 342 for (id = TAILQ_FIRST(&idtab->idlist); id; 343 id = TAILQ_FIRST(&idtab->idlist)) { 344 TAILQ_REMOVE(&idtab->idlist, id, next); 345 free_identity(id); 346 } 347 348 /* Mark that there are no identities. */ 349 idtab->nentries = 0; 350 351 /* Send success. */ 352 send_status(e, 1); 353 } 354 355 /* removes expired keys and returns number of seconds until the next expiry */ 356 static time_t 357 reaper(void) 358 { 359 time_t deadline = 0, now = monotime(); 360 Identity *id, *nxt; 361 362 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 363 nxt = TAILQ_NEXT(id, next); 364 if (id->death == 0) 365 continue; 366 if (now >= id->death) { 367 debug("expiring key '%s'", id->comment); 368 TAILQ_REMOVE(&idtab->idlist, id, next); 369 free_identity(id); 370 idtab->nentries--; 371 } else 372 deadline = (deadline == 0) ? id->death : 373 MINIMUM(deadline, id->death); 374 } 375 if (deadline == 0 || deadline <= now) 376 return 0; 377 else 378 return (deadline - now); 379 } 380 381 static void 382 process_add_identity(SocketEntry *e) 383 { 384 Identity *id; 385 int success = 0, confirm = 0; 386 u_int seconds; 387 char *comment = NULL; 388 time_t death = 0; 389 struct sshkey *k = NULL; 390 u_char ctype; 391 int r = SSH_ERR_INTERNAL_ERROR; 392 393 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 394 k == NULL || 395 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 396 error("%s: decode private key: %s", __func__, ssh_err(r)); 397 goto err; 398 } 399 400 while (sshbuf_len(e->request)) { 401 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 402 error("%s: buffer error: %s", __func__, ssh_err(r)); 403 goto err; 404 } 405 switch (ctype) { 406 case SSH_AGENT_CONSTRAIN_LIFETIME: 407 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 408 error("%s: bad lifetime constraint: %s", 409 __func__, ssh_err(r)); 410 goto err; 411 } 412 death = monotime() + seconds; 413 break; 414 case SSH_AGENT_CONSTRAIN_CONFIRM: 415 confirm = 1; 416 break; 417 default: 418 error("%s: Unknown constraint %d", __func__, ctype); 419 err: 420 sshbuf_reset(e->request); 421 free(comment); 422 sshkey_free(k); 423 goto send; 424 } 425 } 426 427 success = 1; 428 if (lifetime && !death) 429 death = monotime() + lifetime; 430 if ((id = lookup_identity(k)) == NULL) { 431 id = xcalloc(1, sizeof(Identity)); 432 id->key = k; 433 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 434 /* Increment the number of identities. */ 435 idtab->nentries++; 436 } else { 437 sshkey_free(k); 438 free(id->comment); 439 } 440 id->comment = comment; 441 id->death = death; 442 id->confirm = confirm; 443 send: 444 send_status(e, success); 445 } 446 447 /* XXX todo: encrypt sensitive data with passphrase */ 448 static void 449 process_lock_agent(SocketEntry *e, int lock) 450 { 451 int r, success = 0, delay; 452 char *passwd; 453 u_char passwdhash[LOCK_SIZE]; 454 static u_int fail_count = 0; 455 size_t pwlen; 456 457 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 458 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 459 if (pwlen == 0) { 460 debug("empty password not supported"); 461 } else if (locked && !lock) { 462 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 463 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 464 fatal("bcrypt_pbkdf"); 465 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 466 debug("agent unlocked"); 467 locked = 0; 468 fail_count = 0; 469 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 470 success = 1; 471 } else { 472 /* delay in 0.1s increments up to 10s */ 473 if (fail_count < 100) 474 fail_count++; 475 delay = 100000 * fail_count; 476 debug("unlock failed, delaying %0.1lf seconds", 477 (double)delay/1000000); 478 usleep(delay); 479 } 480 explicit_bzero(passwdhash, sizeof(passwdhash)); 481 } else if (!locked && lock) { 482 debug("agent locked"); 483 locked = 1; 484 arc4random_buf(lock_salt, sizeof(lock_salt)); 485 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 486 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 487 fatal("bcrypt_pbkdf"); 488 success = 1; 489 } 490 explicit_bzero(passwd, pwlen); 491 free(passwd); 492 send_status(e, success); 493 } 494 495 static void 496 no_identities(SocketEntry *e) 497 { 498 struct sshbuf *msg; 499 int r; 500 501 if ((msg = sshbuf_new()) == NULL) 502 fatal("%s: sshbuf_new failed", __func__); 503 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 504 (r = sshbuf_put_u32(msg, 0)) != 0 || 505 (r = sshbuf_put_stringb(e->output, msg)) != 0) 506 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 507 sshbuf_free(msg); 508 } 509 510 #ifdef ENABLE_PKCS11 511 static void 512 process_add_smartcard_key(SocketEntry *e) 513 { 514 char *provider = NULL, *pin, canonical_provider[PATH_MAX]; 515 int r, i, count = 0, success = 0, confirm = 0; 516 u_int seconds; 517 time_t death = 0; 518 u_char type; 519 struct sshkey **keys = NULL, *k; 520 Identity *id; 521 522 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 523 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) 524 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 525 526 while (sshbuf_len(e->request)) { 527 if ((r = sshbuf_get_u8(e->request, &type)) != 0) 528 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 529 switch (type) { 530 case SSH_AGENT_CONSTRAIN_LIFETIME: 531 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) 532 fatal("%s: buffer error: %s", 533 __func__, ssh_err(r)); 534 death = monotime() + seconds; 535 break; 536 case SSH_AGENT_CONSTRAIN_CONFIRM: 537 confirm = 1; 538 break; 539 default: 540 error("%s: Unknown constraint type %d", __func__, type); 541 goto send; 542 } 543 } 544 if (realpath(provider, canonical_provider) == NULL) { 545 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 546 provider, strerror(errno)); 547 goto send; 548 } 549 if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { 550 verbose("refusing PKCS#11 add of \"%.100s\": " 551 "provider not whitelisted", canonical_provider); 552 goto send; 553 } 554 debug("%s: add %.100s", __func__, canonical_provider); 555 if (lifetime && !death) 556 death = monotime() + lifetime; 557 558 count = pkcs11_add_provider(canonical_provider, pin, &keys); 559 for (i = 0; i < count; i++) { 560 k = keys[i]; 561 if (lookup_identity(k) == NULL) { 562 id = xcalloc(1, sizeof(Identity)); 563 id->key = k; 564 id->provider = xstrdup(canonical_provider); 565 id->comment = xstrdup(canonical_provider); /* XXX */ 566 id->death = death; 567 id->confirm = confirm; 568 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 569 idtab->nentries++; 570 success = 1; 571 } else { 572 sshkey_free(k); 573 } 574 keys[i] = NULL; 575 } 576 send: 577 free(pin); 578 free(provider); 579 free(keys); 580 send_status(e, success); 581 } 582 583 static void 584 process_remove_smartcard_key(SocketEntry *e) 585 { 586 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 587 int r, success = 0; 588 Identity *id, *nxt; 589 590 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 591 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) 592 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 593 free(pin); 594 595 if (realpath(provider, canonical_provider) == NULL) { 596 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 597 provider, strerror(errno)); 598 goto send; 599 } 600 601 debug("%s: remove %.100s", __func__, canonical_provider); 602 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 603 nxt = TAILQ_NEXT(id, next); 604 /* Skip file--based keys */ 605 if (id->provider == NULL) 606 continue; 607 if (!strcmp(canonical_provider, id->provider)) { 608 TAILQ_REMOVE(&idtab->idlist, id, next); 609 free_identity(id); 610 idtab->nentries--; 611 } 612 } 613 if (pkcs11_del_provider(canonical_provider) == 0) 614 success = 1; 615 else 616 error("%s: pkcs11_del_provider failed", __func__); 617 send: 618 free(provider); 619 send_status(e, success); 620 } 621 #endif /* ENABLE_PKCS11 */ 622 623 /* dispatch incoming messages */ 624 625 static void 626 process_message(SocketEntry *e) 627 { 628 u_int msg_len; 629 u_char type; 630 const u_char *cp; 631 int r; 632 633 if (sshbuf_len(e->input) < 5) 634 return; /* Incomplete message. */ 635 cp = sshbuf_ptr(e->input); 636 msg_len = PEEK_U32(cp); 637 if (msg_len > 256 * 1024) { 638 close_socket(e); 639 return; 640 } 641 if (sshbuf_len(e->input) < msg_len + 4) 642 return; 643 644 /* move the current input to e->request */ 645 sshbuf_reset(e->request); 646 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 647 (r = sshbuf_get_u8(e->request, &type)) != 0) 648 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 649 650 /* check wheter agent is locked */ 651 if (locked && type != SSH_AGENTC_UNLOCK) { 652 sshbuf_reset(e->request); 653 switch (type) { 654 case SSH2_AGENTC_REQUEST_IDENTITIES: 655 /* send empty lists */ 656 no_identities(e); 657 break; 658 default: 659 /* send a fail message for all other request types */ 660 send_status(e, 0); 661 } 662 return; 663 } 664 665 debug("type %d", type); 666 switch (type) { 667 case SSH_AGENTC_LOCK: 668 case SSH_AGENTC_UNLOCK: 669 process_lock_agent(e, type == SSH_AGENTC_LOCK); 670 break; 671 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 672 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 673 break; 674 /* ssh2 */ 675 case SSH2_AGENTC_SIGN_REQUEST: 676 process_sign_request2(e); 677 break; 678 case SSH2_AGENTC_REQUEST_IDENTITIES: 679 process_request_identities(e); 680 break; 681 case SSH2_AGENTC_ADD_IDENTITY: 682 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 683 process_add_identity(e); 684 break; 685 case SSH2_AGENTC_REMOVE_IDENTITY: 686 process_remove_identity(e); 687 break; 688 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 689 process_remove_all_identities(e); 690 break; 691 #ifdef ENABLE_PKCS11 692 case SSH_AGENTC_ADD_SMARTCARD_KEY: 693 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 694 process_add_smartcard_key(e); 695 break; 696 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 697 process_remove_smartcard_key(e); 698 break; 699 #endif /* ENABLE_PKCS11 */ 700 default: 701 /* Unknown message. Respond with failure. */ 702 error("Unknown message %d", type); 703 sshbuf_reset(e->request); 704 send_status(e, 0); 705 break; 706 } 707 } 708 709 static void 710 new_socket(sock_type type, int fd) 711 { 712 u_int i, old_alloc, new_alloc; 713 714 set_nonblock(fd); 715 716 if (fd > max_fd) 717 max_fd = fd; 718 719 for (i = 0; i < sockets_alloc; i++) 720 if (sockets[i].type == AUTH_UNUSED) { 721 sockets[i].fd = fd; 722 if ((sockets[i].input = sshbuf_new()) == NULL) 723 fatal("%s: sshbuf_new failed", __func__); 724 if ((sockets[i].output = sshbuf_new()) == NULL) 725 fatal("%s: sshbuf_new failed", __func__); 726 if ((sockets[i].request = sshbuf_new()) == NULL) 727 fatal("%s: sshbuf_new failed", __func__); 728 sockets[i].type = type; 729 return; 730 } 731 old_alloc = sockets_alloc; 732 new_alloc = sockets_alloc + 10; 733 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 734 for (i = old_alloc; i < new_alloc; i++) 735 sockets[i].type = AUTH_UNUSED; 736 sockets_alloc = new_alloc; 737 sockets[old_alloc].fd = fd; 738 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 739 fatal("%s: sshbuf_new failed", __func__); 740 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 741 fatal("%s: sshbuf_new failed", __func__); 742 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 743 fatal("%s: sshbuf_new failed", __func__); 744 sockets[old_alloc].type = type; 745 } 746 747 static int 748 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 749 struct timeval **tvpp) 750 { 751 u_int i, sz; 752 int n = 0; 753 static struct timeval tv; 754 time_t deadline; 755 756 for (i = 0; i < sockets_alloc; i++) { 757 switch (sockets[i].type) { 758 case AUTH_SOCKET: 759 case AUTH_CONNECTION: 760 n = MAXIMUM(n, sockets[i].fd); 761 break; 762 case AUTH_UNUSED: 763 break; 764 default: 765 fatal("Unknown socket type %d", sockets[i].type); 766 break; 767 } 768 } 769 770 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 771 if (*fdrp == NULL || sz > *nallocp) { 772 free(*fdrp); 773 free(*fdwp); 774 *fdrp = xmalloc(sz); 775 *fdwp = xmalloc(sz); 776 *nallocp = sz; 777 } 778 if (n < *fdl) 779 debug("XXX shrink: %d < %d", n, *fdl); 780 *fdl = n; 781 memset(*fdrp, 0, sz); 782 memset(*fdwp, 0, sz); 783 784 for (i = 0; i < sockets_alloc; i++) { 785 switch (sockets[i].type) { 786 case AUTH_SOCKET: 787 case AUTH_CONNECTION: 788 FD_SET(sockets[i].fd, *fdrp); 789 if (sshbuf_len(sockets[i].output) > 0) 790 FD_SET(sockets[i].fd, *fdwp); 791 break; 792 default: 793 break; 794 } 795 } 796 deadline = reaper(); 797 if (parent_alive_interval != 0) 798 deadline = (deadline == 0) ? parent_alive_interval : 799 MINIMUM(deadline, parent_alive_interval); 800 if (deadline == 0) { 801 *tvpp = NULL; 802 } else { 803 tv.tv_sec = deadline; 804 tv.tv_usec = 0; 805 *tvpp = &tv; 806 } 807 return (1); 808 } 809 810 static void 811 after_select(fd_set *readset, fd_set *writeset) 812 { 813 struct sockaddr_un sunaddr; 814 socklen_t slen; 815 char buf[1024]; 816 int len, sock, r; 817 u_int i, orig_alloc; 818 uid_t euid; 819 gid_t egid; 820 821 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++) 822 switch (sockets[i].type) { 823 case AUTH_UNUSED: 824 break; 825 case AUTH_SOCKET: 826 if (FD_ISSET(sockets[i].fd, readset)) { 827 slen = sizeof(sunaddr); 828 sock = accept(sockets[i].fd, 829 (struct sockaddr *)&sunaddr, &slen); 830 if (sock < 0) { 831 error("accept from AUTH_SOCKET: %s", 832 strerror(errno)); 833 break; 834 } 835 if (getpeereid(sock, &euid, &egid) < 0) { 836 error("getpeereid %d failed: %s", 837 sock, strerror(errno)); 838 close(sock); 839 break; 840 } 841 if ((euid != 0) && (getuid() != euid)) { 842 error("uid mismatch: " 843 "peer euid %u != uid %u", 844 (u_int) euid, (u_int) getuid()); 845 close(sock); 846 break; 847 } 848 new_socket(AUTH_CONNECTION, sock); 849 } 850 break; 851 case AUTH_CONNECTION: 852 if (sshbuf_len(sockets[i].output) > 0 && 853 FD_ISSET(sockets[i].fd, writeset)) { 854 len = write(sockets[i].fd, 855 sshbuf_ptr(sockets[i].output), 856 sshbuf_len(sockets[i].output)); 857 if (len == -1 && (errno == EAGAIN || 858 errno == EINTR)) 859 continue; 860 if (len <= 0) { 861 close_socket(&sockets[i]); 862 break; 863 } 864 if ((r = sshbuf_consume(sockets[i].output, 865 len)) != 0) 866 fatal("%s: buffer error: %s", 867 __func__, ssh_err(r)); 868 } 869 if (FD_ISSET(sockets[i].fd, readset)) { 870 len = read(sockets[i].fd, buf, sizeof(buf)); 871 if (len == -1 && (errno == EAGAIN || 872 errno == EINTR)) 873 continue; 874 if (len <= 0) { 875 close_socket(&sockets[i]); 876 break; 877 } 878 if ((r = sshbuf_put(sockets[i].input, 879 buf, len)) != 0) 880 fatal("%s: buffer error: %s", 881 __func__, ssh_err(r)); 882 explicit_bzero(buf, sizeof(buf)); 883 process_message(&sockets[i]); 884 } 885 break; 886 default: 887 fatal("Unknown type %d", sockets[i].type); 888 } 889 } 890 891 static void 892 cleanup_socket(void) 893 { 894 if (cleanup_pid != 0 && getpid() != cleanup_pid) 895 return; 896 debug("%s: cleanup", __func__); 897 if (socket_name[0]) 898 unlink(socket_name); 899 if (socket_dir[0]) 900 rmdir(socket_dir); 901 } 902 903 void 904 cleanup_exit(int i) 905 { 906 cleanup_socket(); 907 _exit(i); 908 } 909 910 /*ARGSUSED*/ 911 static void 912 cleanup_handler(int sig) 913 { 914 cleanup_socket(); 915 #ifdef ENABLE_PKCS11 916 pkcs11_terminate(); 917 #endif 918 _exit(2); 919 } 920 921 static void 922 check_parent_exists(void) 923 { 924 /* 925 * If our parent has exited then getppid() will return (pid_t)1, 926 * so testing for that should be safe. 927 */ 928 if (parent_pid != -1 && getppid() != parent_pid) { 929 /* printf("Parent has died - Authentication agent exiting.\n"); */ 930 cleanup_socket(); 931 _exit(2); 932 } 933 } 934 935 static void 936 usage(void) 937 { 938 fprintf(stderr, 939 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 940 " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n" 941 " ssh-agent [-c | -s] -k\n"); 942 exit(1); 943 } 944 945 int 946 main(int ac, char **av) 947 { 948 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 949 int sock, fd, ch, result, saved_errno; 950 u_int nalloc; 951 char *shell, *format, *pidstr, *agentsocket = NULL; 952 fd_set *readsetp = NULL, *writesetp = NULL; 953 struct rlimit rlim; 954 extern int optind; 955 extern char *optarg; 956 pid_t pid; 957 char pidstrbuf[1 + 3 * sizeof pid]; 958 struct timeval *tvp = NULL; 959 size_t len; 960 mode_t prev_mask; 961 962 ssh_malloc_init(); /* must be called before any mallocs */ 963 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 964 sanitise_stdfd(); 965 966 /* drop */ 967 setegid(getgid()); 968 setgid(getgid()); 969 970 #ifdef WITH_OPENSSL 971 OpenSSL_add_all_algorithms(); 972 #endif 973 974 while ((ch = getopt(ac, av, "cDdksE:a:P:t:")) != -1) { 975 switch (ch) { 976 case 'E': 977 fingerprint_hash = ssh_digest_alg_by_name(optarg); 978 if (fingerprint_hash == -1) 979 fatal("Invalid hash algorithm \"%s\"", optarg); 980 break; 981 case 'c': 982 if (s_flag) 983 usage(); 984 c_flag++; 985 break; 986 case 'k': 987 k_flag++; 988 break; 989 case 'P': 990 if (pkcs11_whitelist != NULL) 991 fatal("-P option already specified"); 992 pkcs11_whitelist = xstrdup(optarg); 993 break; 994 case 's': 995 if (c_flag) 996 usage(); 997 s_flag++; 998 break; 999 case 'd': 1000 if (d_flag || D_flag) 1001 usage(); 1002 d_flag++; 1003 break; 1004 case 'D': 1005 if (d_flag || D_flag) 1006 usage(); 1007 D_flag++; 1008 break; 1009 case 'a': 1010 agentsocket = optarg; 1011 break; 1012 case 't': 1013 if ((lifetime = convtime(optarg)) == -1) { 1014 fprintf(stderr, "Invalid lifetime\n"); 1015 usage(); 1016 } 1017 break; 1018 default: 1019 usage(); 1020 } 1021 } 1022 ac -= optind; 1023 av += optind; 1024 1025 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1026 usage(); 1027 1028 if (pkcs11_whitelist == NULL) 1029 pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 1030 1031 if (ac == 0 && !c_flag && !s_flag) { 1032 shell = getenv("SHELL"); 1033 if (shell != NULL && (len = strlen(shell)) > 2 && 1034 strncmp(shell + len - 3, "csh", 3) == 0) 1035 c_flag = 1; 1036 } 1037 if (k_flag) { 1038 const char *errstr = NULL; 1039 1040 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1041 if (pidstr == NULL) { 1042 fprintf(stderr, "%s not set, cannot kill agent\n", 1043 SSH_AGENTPID_ENV_NAME); 1044 exit(1); 1045 } 1046 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1047 if (errstr) { 1048 fprintf(stderr, 1049 "%s=\"%s\", which is not a good PID: %s\n", 1050 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1051 exit(1); 1052 } 1053 if (kill(pid, SIGTERM) == -1) { 1054 perror("kill"); 1055 exit(1); 1056 } 1057 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1058 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1059 printf(format, SSH_AGENTPID_ENV_NAME); 1060 printf("echo Agent pid %ld killed;\n", (long)pid); 1061 exit(0); 1062 } 1063 parent_pid = getpid(); 1064 1065 if (agentsocket == NULL) { 1066 /* Create private directory for agent socket */ 1067 mktemp_proto(socket_dir, sizeof(socket_dir)); 1068 if (mkdtemp(socket_dir) == NULL) { 1069 perror("mkdtemp: private socket dir"); 1070 exit(1); 1071 } 1072 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1073 (long)parent_pid); 1074 } else { 1075 /* Try to use specified agent socket */ 1076 socket_dir[0] = '\0'; 1077 strlcpy(socket_name, agentsocket, sizeof socket_name); 1078 } 1079 1080 /* 1081 * Create socket early so it will exist before command gets run from 1082 * the parent. 1083 */ 1084 prev_mask = umask(0177); 1085 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1086 if (sock < 0) { 1087 /* XXX - unix_listener() calls error() not perror() */ 1088 *socket_name = '\0'; /* Don't unlink any existing file */ 1089 cleanup_exit(1); 1090 } 1091 umask(prev_mask); 1092 1093 /* 1094 * Fork, and have the parent execute the command, if any, or present 1095 * the socket data. The child continues as the authentication agent. 1096 */ 1097 if (D_flag || d_flag) { 1098 log_init(__progname, 1099 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1100 SYSLOG_FACILITY_AUTH, 1); 1101 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1102 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1103 SSH_AUTHSOCKET_ENV_NAME); 1104 printf("echo Agent pid %ld;\n", (long)parent_pid); 1105 fflush(stdout); 1106 goto skip; 1107 } 1108 pid = fork(); 1109 if (pid == -1) { 1110 perror("fork"); 1111 cleanup_exit(1); 1112 } 1113 if (pid != 0) { /* Parent - execute the given command. */ 1114 close(sock); 1115 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1116 if (ac == 0) { 1117 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1118 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1119 SSH_AUTHSOCKET_ENV_NAME); 1120 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1121 SSH_AGENTPID_ENV_NAME); 1122 printf("echo Agent pid %ld;\n", (long)pid); 1123 exit(0); 1124 } 1125 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1126 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1127 perror("setenv"); 1128 exit(1); 1129 } 1130 execvp(av[0], av); 1131 perror(av[0]); 1132 exit(1); 1133 } 1134 /* child */ 1135 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1136 1137 if (setsid() == -1) { 1138 error("setsid: %s", strerror(errno)); 1139 cleanup_exit(1); 1140 } 1141 1142 (void)chdir("/"); 1143 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1144 /* XXX might close listen socket */ 1145 (void)dup2(fd, STDIN_FILENO); 1146 (void)dup2(fd, STDOUT_FILENO); 1147 (void)dup2(fd, STDERR_FILENO); 1148 if (fd > 2) 1149 close(fd); 1150 } 1151 1152 /* deny core dumps, since memory contains unencrypted private keys */ 1153 rlim.rlim_cur = rlim.rlim_max = 0; 1154 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1155 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1156 cleanup_exit(1); 1157 } 1158 1159 skip: 1160 1161 cleanup_pid = getpid(); 1162 1163 #ifdef ENABLE_PKCS11 1164 pkcs11_init(0); 1165 #endif 1166 new_socket(AUTH_SOCKET, sock); 1167 if (ac > 0) 1168 parent_alive_interval = 10; 1169 idtab_init(); 1170 signal(SIGPIPE, SIG_IGN); 1171 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1172 signal(SIGHUP, cleanup_handler); 1173 signal(SIGTERM, cleanup_handler); 1174 nalloc = 0; 1175 1176 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1177 fatal("%s: pledge: %s", __progname, strerror(errno)); 1178 1179 while (1) { 1180 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp); 1181 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp); 1182 saved_errno = errno; 1183 if (parent_alive_interval != 0) 1184 check_parent_exists(); 1185 (void) reaper(); /* remove expired keys */ 1186 if (result < 0) { 1187 if (saved_errno == EINTR) 1188 continue; 1189 fatal("select: %s", strerror(saved_errno)); 1190 } else if (result > 0) 1191 after_select(readsetp, writesetp); 1192 } 1193 /* NOTREACHED */ 1194 } 1195