1 /* $OpenBSD: ssh-agent.c,v 1.222 2017/07/01 13:50:45 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 "sshbuf.h" 64 #include "sshkey.h" 65 #include "authfd.h" 66 #include "compat.h" 67 #include "log.h" 68 #include "misc.h" 69 #include "digest.h" 70 #include "ssherr.h" 71 #include "match.h" 72 73 #ifdef ENABLE_PKCS11 74 #include "ssh-pkcs11.h" 75 #endif 76 77 #ifndef DEFAULT_PKCS11_WHITELIST 78 # define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" 79 #endif 80 81 typedef enum { 82 AUTH_UNUSED, 83 AUTH_SOCKET, 84 AUTH_CONNECTION 85 } sock_type; 86 87 typedef struct { 88 int fd; 89 sock_type type; 90 struct sshbuf *input; 91 struct sshbuf *output; 92 struct sshbuf *request; 93 } SocketEntry; 94 95 u_int sockets_alloc = 0; 96 SocketEntry *sockets = NULL; 97 98 typedef struct identity { 99 TAILQ_ENTRY(identity) next; 100 struct sshkey *key; 101 char *comment; 102 char *provider; 103 time_t death; 104 u_int confirm; 105 } Identity; 106 107 struct idtable { 108 int nentries; 109 TAILQ_HEAD(idqueue, identity) idlist; 110 }; 111 112 /* private key table */ 113 struct idtable *idtab; 114 115 int max_fd = 0; 116 117 /* pid of shell == parent of agent */ 118 pid_t parent_pid = -1; 119 time_t parent_alive_interval = 0; 120 121 /* pid of process for which cleanup_socket is applicable */ 122 pid_t cleanup_pid = 0; 123 124 /* pathname and directory for AUTH_SOCKET */ 125 char socket_name[PATH_MAX]; 126 char socket_dir[PATH_MAX]; 127 128 /* PKCS#11 path whitelist */ 129 static char *pkcs11_whitelist; 130 131 /* locking */ 132 #define LOCK_SIZE 32 133 #define LOCK_SALT_SIZE 16 134 #define LOCK_ROUNDS 1 135 int locked = 0; 136 u_char lock_pwhash[LOCK_SIZE]; 137 u_char lock_salt[LOCK_SALT_SIZE]; 138 139 extern char *__progname; 140 141 /* Default lifetime in seconds (0 == forever) */ 142 static long lifetime = 0; 143 144 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 145 146 static void 147 close_socket(SocketEntry *e) 148 { 149 close(e->fd); 150 e->fd = -1; 151 e->type = AUTH_UNUSED; 152 sshbuf_free(e->input); 153 sshbuf_free(e->output); 154 sshbuf_free(e->request); 155 } 156 157 static void 158 idtab_init(void) 159 { 160 idtab = xcalloc(1, sizeof(*idtab)); 161 TAILQ_INIT(&idtab->idlist); 162 idtab->nentries = 0; 163 } 164 165 static void 166 free_identity(Identity *id) 167 { 168 sshkey_free(id->key); 169 free(id->provider); 170 free(id->comment); 171 free(id); 172 } 173 174 /* return matching private key for given public key */ 175 static Identity * 176 lookup_identity(struct sshkey *key) 177 { 178 Identity *id; 179 180 TAILQ_FOREACH(id, &idtab->idlist, next) { 181 if (sshkey_equal(key, id->key)) 182 return (id); 183 } 184 return (NULL); 185 } 186 187 /* Check confirmation of keysign request */ 188 static int 189 confirm_key(Identity *id) 190 { 191 char *p; 192 int ret = -1; 193 194 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 195 if (p != NULL && 196 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 197 id->comment, p)) 198 ret = 0; 199 free(p); 200 201 return (ret); 202 } 203 204 static void 205 send_status(SocketEntry *e, int success) 206 { 207 int r; 208 209 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 210 (r = sshbuf_put_u8(e->output, success ? 211 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 212 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 213 } 214 215 /* send list of supported public keys to 'client' */ 216 static void 217 process_request_identities(SocketEntry *e) 218 { 219 Identity *id; 220 struct sshbuf *msg; 221 int r; 222 223 if ((msg = sshbuf_new()) == NULL) 224 fatal("%s: sshbuf_new failed", __func__); 225 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 226 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 227 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 228 TAILQ_FOREACH(id, &idtab->idlist, next) { 229 if ((r = sshkey_puts(id->key, msg)) != 0 || 230 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 231 error("%s: put key/comment: %s", __func__, 232 ssh_err(r)); 233 continue; 234 } 235 } 236 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 237 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 238 sshbuf_free(msg); 239 } 240 241 242 static char * 243 agent_decode_alg(struct sshkey *key, u_int flags) 244 { 245 if (key->type == KEY_RSA) { 246 if (flags & SSH_AGENT_RSA_SHA2_256) 247 return "rsa-sha2-256"; 248 else if (flags & SSH_AGENT_RSA_SHA2_512) 249 return "rsa-sha2-512"; 250 } 251 return NULL; 252 } 253 254 /* ssh2 only */ 255 static void 256 process_sign_request2(SocketEntry *e) 257 { 258 const u_char *data; 259 u_char *signature = NULL; 260 size_t dlen, slen = 0; 261 u_int compat = 0, flags; 262 int r, ok = -1; 263 struct sshbuf *msg; 264 struct sshkey *key = NULL; 265 struct identity *id; 266 267 if ((msg = sshbuf_new()) == NULL) 268 fatal("%s: sshbuf_new failed", __func__); 269 if ((r = sshkey_froms(e->request, &key)) != 0 || 270 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 271 (r = sshbuf_get_u32(e->request, &flags)) != 0) 272 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 273 if (flags & SSH_AGENT_OLD_SIGNATURE) 274 compat = SSH_BUG_SIGBLOB; 275 if ((id = lookup_identity(key)) == NULL) { 276 verbose("%s: %s key not found", __func__, sshkey_type(key)); 277 goto send; 278 } 279 if (id->confirm && confirm_key(id) != 0) { 280 verbose("%s: user refused key", __func__); 281 goto send; 282 } 283 if ((r = sshkey_sign(id->key, &signature, &slen, 284 data, dlen, agent_decode_alg(key, flags), compat)) != 0) { 285 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 286 goto send; 287 } 288 /* Success */ 289 ok = 0; 290 send: 291 sshkey_free(key); 292 if (ok == 0) { 293 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 294 (r = sshbuf_put_string(msg, signature, slen)) != 0) 295 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 296 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 297 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 298 299 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 300 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 301 302 sshbuf_free(msg); 303 free(signature); 304 } 305 306 /* shared */ 307 static void 308 process_remove_identity(SocketEntry *e) 309 { 310 int r, success = 0; 311 struct sshkey *key = NULL; 312 Identity *id; 313 314 if ((r = sshkey_froms(e->request, &key)) != 0) { 315 error("%s: get key: %s", __func__, ssh_err(r)); 316 goto done; 317 } 318 if ((id = lookup_identity(key)) == NULL) { 319 debug("%s: key not found", __func__); 320 goto done; 321 } 322 /* We have this key, free it. */ 323 if (idtab->nentries < 1) 324 fatal("%s: internal error: nentries %d", 325 __func__, idtab->nentries); 326 TAILQ_REMOVE(&idtab->idlist, id, next); 327 free_identity(id); 328 idtab->nentries--; 329 sshkey_free(key); 330 success = 1; 331 done: 332 send_status(e, success); 333 } 334 335 static void 336 process_remove_all_identities(SocketEntry *e) 337 { 338 Identity *id; 339 340 /* Loop over all identities and clear the keys. */ 341 for (id = TAILQ_FIRST(&idtab->idlist); id; 342 id = TAILQ_FIRST(&idtab->idlist)) { 343 TAILQ_REMOVE(&idtab->idlist, id, next); 344 free_identity(id); 345 } 346 347 /* Mark that there are no identities. */ 348 idtab->nentries = 0; 349 350 /* Send success. */ 351 send_status(e, 1); 352 } 353 354 /* removes expired keys and returns number of seconds until the next expiry */ 355 static time_t 356 reaper(void) 357 { 358 time_t deadline = 0, now = monotime(); 359 Identity *id, *nxt; 360 361 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 362 nxt = TAILQ_NEXT(id, next); 363 if (id->death == 0) 364 continue; 365 if (now >= id->death) { 366 debug("expiring key '%s'", id->comment); 367 TAILQ_REMOVE(&idtab->idlist, id, next); 368 free_identity(id); 369 idtab->nentries--; 370 } else 371 deadline = (deadline == 0) ? id->death : 372 MINIMUM(deadline, id->death); 373 } 374 if (deadline == 0 || deadline <= now) 375 return 0; 376 else 377 return (deadline - now); 378 } 379 380 static void 381 process_add_identity(SocketEntry *e) 382 { 383 Identity *id; 384 int success = 0, confirm = 0; 385 u_int seconds; 386 char *comment = NULL; 387 time_t death = 0; 388 struct sshkey *k = NULL; 389 u_char ctype; 390 int r = SSH_ERR_INTERNAL_ERROR; 391 392 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 393 k == NULL || 394 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 395 error("%s: decode private key: %s", __func__, ssh_err(r)); 396 goto err; 397 } 398 399 while (sshbuf_len(e->request)) { 400 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 401 error("%s: buffer error: %s", __func__, ssh_err(r)); 402 goto err; 403 } 404 switch (ctype) { 405 case SSH_AGENT_CONSTRAIN_LIFETIME: 406 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 407 error("%s: bad lifetime constraint: %s", 408 __func__, ssh_err(r)); 409 goto err; 410 } 411 death = monotime() + seconds; 412 break; 413 case SSH_AGENT_CONSTRAIN_CONFIRM: 414 confirm = 1; 415 break; 416 default: 417 error("%s: Unknown constraint %d", __func__, ctype); 418 err: 419 sshbuf_reset(e->request); 420 free(comment); 421 sshkey_free(k); 422 goto send; 423 } 424 } 425 426 success = 1; 427 if (lifetime && !death) 428 death = monotime() + lifetime; 429 if ((id = lookup_identity(k)) == NULL) { 430 id = xcalloc(1, sizeof(Identity)); 431 id->key = k; 432 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 433 /* Increment the number of identities. */ 434 idtab->nentries++; 435 } else { 436 sshkey_free(k); 437 free(id->comment); 438 } 439 id->comment = comment; 440 id->death = death; 441 id->confirm = confirm; 442 send: 443 send_status(e, success); 444 } 445 446 /* XXX todo: encrypt sensitive data with passphrase */ 447 static void 448 process_lock_agent(SocketEntry *e, int lock) 449 { 450 int r, success = 0, delay; 451 char *passwd; 452 u_char passwdhash[LOCK_SIZE]; 453 static u_int fail_count = 0; 454 size_t pwlen; 455 456 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 457 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 458 if (pwlen == 0) { 459 debug("empty password not supported"); 460 } else if (locked && !lock) { 461 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 462 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 463 fatal("bcrypt_pbkdf"); 464 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 465 debug("agent unlocked"); 466 locked = 0; 467 fail_count = 0; 468 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 469 success = 1; 470 } else { 471 /* delay in 0.1s increments up to 10s */ 472 if (fail_count < 100) 473 fail_count++; 474 delay = 100000 * fail_count; 475 debug("unlock failed, delaying %0.1lf seconds", 476 (double)delay/1000000); 477 usleep(delay); 478 } 479 explicit_bzero(passwdhash, sizeof(passwdhash)); 480 } else if (!locked && lock) { 481 debug("agent locked"); 482 locked = 1; 483 arc4random_buf(lock_salt, sizeof(lock_salt)); 484 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 485 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 486 fatal("bcrypt_pbkdf"); 487 success = 1; 488 } 489 explicit_bzero(passwd, pwlen); 490 free(passwd); 491 send_status(e, success); 492 } 493 494 static void 495 no_identities(SocketEntry *e) 496 { 497 struct sshbuf *msg; 498 int r; 499 500 if ((msg = sshbuf_new()) == NULL) 501 fatal("%s: sshbuf_new failed", __func__); 502 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 503 (r = sshbuf_put_u32(msg, 0)) != 0 || 504 (r = sshbuf_put_stringb(e->output, msg)) != 0) 505 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 506 sshbuf_free(msg); 507 } 508 509 #ifdef ENABLE_PKCS11 510 static void 511 process_add_smartcard_key(SocketEntry *e) 512 { 513 char *provider = NULL, *pin, canonical_provider[PATH_MAX]; 514 int r, i, count = 0, success = 0, confirm = 0; 515 u_int seconds; 516 time_t death = 0; 517 u_char type; 518 struct sshkey **keys = NULL, *k; 519 Identity *id; 520 521 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 522 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) 523 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 524 525 while (sshbuf_len(e->request)) { 526 if ((r = sshbuf_get_u8(e->request, &type)) != 0) 527 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 528 switch (type) { 529 case SSH_AGENT_CONSTRAIN_LIFETIME: 530 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) 531 fatal("%s: buffer error: %s", 532 __func__, ssh_err(r)); 533 death = monotime() + seconds; 534 break; 535 case SSH_AGENT_CONSTRAIN_CONFIRM: 536 confirm = 1; 537 break; 538 default: 539 error("%s: Unknown constraint type %d", __func__, type); 540 goto send; 541 } 542 } 543 if (realpath(provider, canonical_provider) == NULL) { 544 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 545 provider, strerror(errno)); 546 goto send; 547 } 548 if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { 549 verbose("refusing PKCS#11 add of \"%.100s\": " 550 "provider not whitelisted", canonical_provider); 551 goto send; 552 } 553 debug("%s: add %.100s", __func__, canonical_provider); 554 if (lifetime && !death) 555 death = monotime() + lifetime; 556 557 count = pkcs11_add_provider(canonical_provider, pin, &keys); 558 for (i = 0; i < count; i++) { 559 k = keys[i]; 560 if (lookup_identity(k) == NULL) { 561 id = xcalloc(1, sizeof(Identity)); 562 id->key = k; 563 id->provider = xstrdup(canonical_provider); 564 id->comment = xstrdup(canonical_provider); /* XXX */ 565 id->death = death; 566 id->confirm = confirm; 567 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 568 idtab->nentries++; 569 success = 1; 570 } else { 571 sshkey_free(k); 572 } 573 keys[i] = NULL; 574 } 575 send: 576 free(pin); 577 free(provider); 578 free(keys); 579 send_status(e, success); 580 } 581 582 static void 583 process_remove_smartcard_key(SocketEntry *e) 584 { 585 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 586 int r, success = 0; 587 Identity *id, *nxt; 588 589 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 590 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) 591 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 592 free(pin); 593 594 if (realpath(provider, canonical_provider) == NULL) { 595 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 596 provider, strerror(errno)); 597 goto send; 598 } 599 600 debug("%s: remove %.100s", __func__, canonical_provider); 601 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 602 nxt = TAILQ_NEXT(id, next); 603 /* Skip file--based keys */ 604 if (id->provider == NULL) 605 continue; 606 if (!strcmp(canonical_provider, id->provider)) { 607 TAILQ_REMOVE(&idtab->idlist, id, next); 608 free_identity(id); 609 idtab->nentries--; 610 } 611 } 612 if (pkcs11_del_provider(canonical_provider) == 0) 613 success = 1; 614 else 615 error("%s: pkcs11_del_provider failed", __func__); 616 send: 617 free(provider); 618 send_status(e, success); 619 } 620 #endif /* ENABLE_PKCS11 */ 621 622 /* dispatch incoming messages */ 623 624 static void 625 process_message(SocketEntry *e) 626 { 627 u_int msg_len; 628 u_char type; 629 const u_char *cp; 630 int r; 631 632 if (sshbuf_len(e->input) < 5) 633 return; /* Incomplete message. */ 634 cp = sshbuf_ptr(e->input); 635 msg_len = PEEK_U32(cp); 636 if (msg_len > 256 * 1024) { 637 close_socket(e); 638 return; 639 } 640 if (sshbuf_len(e->input) < msg_len + 4) 641 return; 642 643 /* move the current input to e->request */ 644 sshbuf_reset(e->request); 645 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 646 (r = sshbuf_get_u8(e->request, &type)) != 0) 647 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 648 649 /* check wheter agent is locked */ 650 if (locked && type != SSH_AGENTC_UNLOCK) { 651 sshbuf_reset(e->request); 652 switch (type) { 653 case SSH2_AGENTC_REQUEST_IDENTITIES: 654 /* send empty lists */ 655 no_identities(e); 656 break; 657 default: 658 /* send a fail message for all other request types */ 659 send_status(e, 0); 660 } 661 return; 662 } 663 664 debug("type %d", type); 665 switch (type) { 666 case SSH_AGENTC_LOCK: 667 case SSH_AGENTC_UNLOCK: 668 process_lock_agent(e, type == SSH_AGENTC_LOCK); 669 break; 670 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 671 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 672 break; 673 /* ssh2 */ 674 case SSH2_AGENTC_SIGN_REQUEST: 675 process_sign_request2(e); 676 break; 677 case SSH2_AGENTC_REQUEST_IDENTITIES: 678 process_request_identities(e); 679 break; 680 case SSH2_AGENTC_ADD_IDENTITY: 681 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 682 process_add_identity(e); 683 break; 684 case SSH2_AGENTC_REMOVE_IDENTITY: 685 process_remove_identity(e); 686 break; 687 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 688 process_remove_all_identities(e); 689 break; 690 #ifdef ENABLE_PKCS11 691 case SSH_AGENTC_ADD_SMARTCARD_KEY: 692 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 693 process_add_smartcard_key(e); 694 break; 695 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 696 process_remove_smartcard_key(e); 697 break; 698 #endif /* ENABLE_PKCS11 */ 699 default: 700 /* Unknown message. Respond with failure. */ 701 error("Unknown message %d", type); 702 sshbuf_reset(e->request); 703 send_status(e, 0); 704 break; 705 } 706 } 707 708 static void 709 new_socket(sock_type type, int fd) 710 { 711 u_int i, old_alloc, new_alloc; 712 713 set_nonblock(fd); 714 715 if (fd > max_fd) 716 max_fd = fd; 717 718 for (i = 0; i < sockets_alloc; i++) 719 if (sockets[i].type == AUTH_UNUSED) { 720 sockets[i].fd = fd; 721 if ((sockets[i].input = sshbuf_new()) == NULL) 722 fatal("%s: sshbuf_new failed", __func__); 723 if ((sockets[i].output = sshbuf_new()) == NULL) 724 fatal("%s: sshbuf_new failed", __func__); 725 if ((sockets[i].request = sshbuf_new()) == NULL) 726 fatal("%s: sshbuf_new failed", __func__); 727 sockets[i].type = type; 728 return; 729 } 730 old_alloc = sockets_alloc; 731 new_alloc = sockets_alloc + 10; 732 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 733 for (i = old_alloc; i < new_alloc; i++) 734 sockets[i].type = AUTH_UNUSED; 735 sockets_alloc = new_alloc; 736 sockets[old_alloc].fd = fd; 737 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 738 fatal("%s: sshbuf_new failed", __func__); 739 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 740 fatal("%s: sshbuf_new failed", __func__); 741 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 742 fatal("%s: sshbuf_new failed", __func__); 743 sockets[old_alloc].type = type; 744 } 745 746 static int 747 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 748 struct timeval **tvpp) 749 { 750 u_int i, sz; 751 int n = 0; 752 static struct timeval tv; 753 time_t deadline; 754 755 for (i = 0; i < sockets_alloc; i++) { 756 switch (sockets[i].type) { 757 case AUTH_SOCKET: 758 case AUTH_CONNECTION: 759 n = MAXIMUM(n, sockets[i].fd); 760 break; 761 case AUTH_UNUSED: 762 break; 763 default: 764 fatal("Unknown socket type %d", sockets[i].type); 765 break; 766 } 767 } 768 769 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 770 if (*fdrp == NULL || sz > *nallocp) { 771 free(*fdrp); 772 free(*fdwp); 773 *fdrp = xmalloc(sz); 774 *fdwp = xmalloc(sz); 775 *nallocp = sz; 776 } 777 if (n < *fdl) 778 debug("XXX shrink: %d < %d", n, *fdl); 779 *fdl = n; 780 memset(*fdrp, 0, sz); 781 memset(*fdwp, 0, sz); 782 783 for (i = 0; i < sockets_alloc; i++) { 784 switch (sockets[i].type) { 785 case AUTH_SOCKET: 786 case AUTH_CONNECTION: 787 FD_SET(sockets[i].fd, *fdrp); 788 if (sshbuf_len(sockets[i].output) > 0) 789 FD_SET(sockets[i].fd, *fdwp); 790 break; 791 default: 792 break; 793 } 794 } 795 deadline = reaper(); 796 if (parent_alive_interval != 0) 797 deadline = (deadline == 0) ? parent_alive_interval : 798 MINIMUM(deadline, parent_alive_interval); 799 if (deadline == 0) { 800 *tvpp = NULL; 801 } else { 802 tv.tv_sec = deadline; 803 tv.tv_usec = 0; 804 *tvpp = &tv; 805 } 806 return (1); 807 } 808 809 static void 810 after_select(fd_set *readset, fd_set *writeset) 811 { 812 struct sockaddr_un sunaddr; 813 socklen_t slen; 814 char buf[1024]; 815 int len, sock, r; 816 u_int i, orig_alloc; 817 uid_t euid; 818 gid_t egid; 819 820 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++) 821 switch (sockets[i].type) { 822 case AUTH_UNUSED: 823 break; 824 case AUTH_SOCKET: 825 if (FD_ISSET(sockets[i].fd, readset)) { 826 slen = sizeof(sunaddr); 827 sock = accept(sockets[i].fd, 828 (struct sockaddr *)&sunaddr, &slen); 829 if (sock < 0) { 830 error("accept from AUTH_SOCKET: %s", 831 strerror(errno)); 832 break; 833 } 834 if (getpeereid(sock, &euid, &egid) < 0) { 835 error("getpeereid %d failed: %s", 836 sock, strerror(errno)); 837 close(sock); 838 break; 839 } 840 if ((euid != 0) && (getuid() != euid)) { 841 error("uid mismatch: " 842 "peer euid %u != uid %u", 843 (u_int) euid, (u_int) getuid()); 844 close(sock); 845 break; 846 } 847 new_socket(AUTH_CONNECTION, sock); 848 } 849 break; 850 case AUTH_CONNECTION: 851 if (sshbuf_len(sockets[i].output) > 0 && 852 FD_ISSET(sockets[i].fd, writeset)) { 853 len = write(sockets[i].fd, 854 sshbuf_ptr(sockets[i].output), 855 sshbuf_len(sockets[i].output)); 856 if (len == -1 && (errno == EAGAIN || 857 errno == EINTR)) 858 continue; 859 if (len <= 0) { 860 close_socket(&sockets[i]); 861 break; 862 } 863 if ((r = sshbuf_consume(sockets[i].output, 864 len)) != 0) 865 fatal("%s: buffer error: %s", 866 __func__, ssh_err(r)); 867 } 868 if (FD_ISSET(sockets[i].fd, readset)) { 869 len = read(sockets[i].fd, buf, sizeof(buf)); 870 if (len == -1 && (errno == EAGAIN || 871 errno == EINTR)) 872 continue; 873 if (len <= 0) { 874 close_socket(&sockets[i]); 875 break; 876 } 877 if ((r = sshbuf_put(sockets[i].input, 878 buf, len)) != 0) 879 fatal("%s: buffer error: %s", 880 __func__, ssh_err(r)); 881 explicit_bzero(buf, sizeof(buf)); 882 process_message(&sockets[i]); 883 } 884 break; 885 default: 886 fatal("Unknown type %d", sockets[i].type); 887 } 888 } 889 890 static void 891 cleanup_socket(void) 892 { 893 if (cleanup_pid != 0 && getpid() != cleanup_pid) 894 return; 895 debug("%s: cleanup", __func__); 896 if (socket_name[0]) 897 unlink(socket_name); 898 if (socket_dir[0]) 899 rmdir(socket_dir); 900 } 901 902 void 903 cleanup_exit(int i) 904 { 905 cleanup_socket(); 906 _exit(i); 907 } 908 909 /*ARGSUSED*/ 910 static void 911 cleanup_handler(int sig) 912 { 913 cleanup_socket(); 914 #ifdef ENABLE_PKCS11 915 pkcs11_terminate(); 916 #endif 917 _exit(2); 918 } 919 920 static void 921 check_parent_exists(void) 922 { 923 /* 924 * If our parent has exited then getppid() will return (pid_t)1, 925 * so testing for that should be safe. 926 */ 927 if (parent_pid != -1 && getppid() != parent_pid) { 928 /* printf("Parent has died - Authentication agent exiting.\n"); */ 929 cleanup_socket(); 930 _exit(2); 931 } 932 } 933 934 static void 935 usage(void) 936 { 937 fprintf(stderr, 938 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 939 " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n" 940 " ssh-agent [-c | -s] -k\n"); 941 exit(1); 942 } 943 944 int 945 main(int ac, char **av) 946 { 947 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 948 int sock, fd, ch, result, saved_errno; 949 u_int nalloc; 950 char *shell, *format, *pidstr, *agentsocket = NULL; 951 fd_set *readsetp = NULL, *writesetp = NULL; 952 struct rlimit rlim; 953 extern int optind; 954 extern char *optarg; 955 pid_t pid; 956 char pidstrbuf[1 + 3 * sizeof pid]; 957 struct timeval *tvp = NULL; 958 size_t len; 959 mode_t prev_mask; 960 961 ssh_malloc_init(); /* must be called before any mallocs */ 962 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 963 sanitise_stdfd(); 964 965 /* drop */ 966 setegid(getgid()); 967 setgid(getgid()); 968 969 #ifdef WITH_OPENSSL 970 OpenSSL_add_all_algorithms(); 971 #endif 972 973 while ((ch = getopt(ac, av, "cDdksE:a:P:t:")) != -1) { 974 switch (ch) { 975 case 'E': 976 fingerprint_hash = ssh_digest_alg_by_name(optarg); 977 if (fingerprint_hash == -1) 978 fatal("Invalid hash algorithm \"%s\"", optarg); 979 break; 980 case 'c': 981 if (s_flag) 982 usage(); 983 c_flag++; 984 break; 985 case 'k': 986 k_flag++; 987 break; 988 case 'P': 989 if (pkcs11_whitelist != NULL) 990 fatal("-P option already specified"); 991 pkcs11_whitelist = xstrdup(optarg); 992 break; 993 case 's': 994 if (c_flag) 995 usage(); 996 s_flag++; 997 break; 998 case 'd': 999 if (d_flag || D_flag) 1000 usage(); 1001 d_flag++; 1002 break; 1003 case 'D': 1004 if (d_flag || D_flag) 1005 usage(); 1006 D_flag++; 1007 break; 1008 case 'a': 1009 agentsocket = optarg; 1010 break; 1011 case 't': 1012 if ((lifetime = convtime(optarg)) == -1) { 1013 fprintf(stderr, "Invalid lifetime\n"); 1014 usage(); 1015 } 1016 break; 1017 default: 1018 usage(); 1019 } 1020 } 1021 ac -= optind; 1022 av += optind; 1023 1024 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1025 usage(); 1026 1027 if (pkcs11_whitelist == NULL) 1028 pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 1029 1030 if (ac == 0 && !c_flag && !s_flag) { 1031 shell = getenv("SHELL"); 1032 if (shell != NULL && (len = strlen(shell)) > 2 && 1033 strncmp(shell + len - 3, "csh", 3) == 0) 1034 c_flag = 1; 1035 } 1036 if (k_flag) { 1037 const char *errstr = NULL; 1038 1039 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1040 if (pidstr == NULL) { 1041 fprintf(stderr, "%s not set, cannot kill agent\n", 1042 SSH_AGENTPID_ENV_NAME); 1043 exit(1); 1044 } 1045 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1046 if (errstr) { 1047 fprintf(stderr, 1048 "%s=\"%s\", which is not a good PID: %s\n", 1049 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1050 exit(1); 1051 } 1052 if (kill(pid, SIGTERM) == -1) { 1053 perror("kill"); 1054 exit(1); 1055 } 1056 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1057 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1058 printf(format, SSH_AGENTPID_ENV_NAME); 1059 printf("echo Agent pid %ld killed;\n", (long)pid); 1060 exit(0); 1061 } 1062 parent_pid = getpid(); 1063 1064 if (agentsocket == NULL) { 1065 /* Create private directory for agent socket */ 1066 mktemp_proto(socket_dir, sizeof(socket_dir)); 1067 if (mkdtemp(socket_dir) == NULL) { 1068 perror("mkdtemp: private socket dir"); 1069 exit(1); 1070 } 1071 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1072 (long)parent_pid); 1073 } else { 1074 /* Try to use specified agent socket */ 1075 socket_dir[0] = '\0'; 1076 strlcpy(socket_name, agentsocket, sizeof socket_name); 1077 } 1078 1079 /* 1080 * Create socket early so it will exist before command gets run from 1081 * the parent. 1082 */ 1083 prev_mask = umask(0177); 1084 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1085 if (sock < 0) { 1086 /* XXX - unix_listener() calls error() not perror() */ 1087 *socket_name = '\0'; /* Don't unlink any existing file */ 1088 cleanup_exit(1); 1089 } 1090 umask(prev_mask); 1091 1092 /* 1093 * Fork, and have the parent execute the command, if any, or present 1094 * the socket data. The child continues as the authentication agent. 1095 */ 1096 if (D_flag || d_flag) { 1097 log_init(__progname, 1098 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1099 SYSLOG_FACILITY_AUTH, 1); 1100 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1101 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1102 SSH_AUTHSOCKET_ENV_NAME); 1103 printf("echo Agent pid %ld;\n", (long)parent_pid); 1104 fflush(stdout); 1105 goto skip; 1106 } 1107 pid = fork(); 1108 if (pid == -1) { 1109 perror("fork"); 1110 cleanup_exit(1); 1111 } 1112 if (pid != 0) { /* Parent - execute the given command. */ 1113 close(sock); 1114 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1115 if (ac == 0) { 1116 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1117 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1118 SSH_AUTHSOCKET_ENV_NAME); 1119 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1120 SSH_AGENTPID_ENV_NAME); 1121 printf("echo Agent pid %ld;\n", (long)pid); 1122 exit(0); 1123 } 1124 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1125 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1126 perror("setenv"); 1127 exit(1); 1128 } 1129 execvp(av[0], av); 1130 perror(av[0]); 1131 exit(1); 1132 } 1133 /* child */ 1134 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1135 1136 if (setsid() == -1) { 1137 error("setsid: %s", strerror(errno)); 1138 cleanup_exit(1); 1139 } 1140 1141 (void)chdir("/"); 1142 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1143 /* XXX might close listen socket */ 1144 (void)dup2(fd, STDIN_FILENO); 1145 (void)dup2(fd, STDOUT_FILENO); 1146 (void)dup2(fd, STDERR_FILENO); 1147 if (fd > 2) 1148 close(fd); 1149 } 1150 1151 /* deny core dumps, since memory contains unencrypted private keys */ 1152 rlim.rlim_cur = rlim.rlim_max = 0; 1153 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1154 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1155 cleanup_exit(1); 1156 } 1157 1158 skip: 1159 1160 cleanup_pid = getpid(); 1161 1162 #ifdef ENABLE_PKCS11 1163 pkcs11_init(0); 1164 #endif 1165 new_socket(AUTH_SOCKET, sock); 1166 if (ac > 0) 1167 parent_alive_interval = 10; 1168 idtab_init(); 1169 signal(SIGPIPE, SIG_IGN); 1170 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1171 signal(SIGHUP, cleanup_handler); 1172 signal(SIGTERM, cleanup_handler); 1173 nalloc = 0; 1174 1175 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1176 fatal("%s: pledge: %s", __progname, strerror(errno)); 1177 1178 while (1) { 1179 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp); 1180 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp); 1181 saved_errno = errno; 1182 if (parent_alive_interval != 0) 1183 check_parent_exists(); 1184 (void) reaper(); /* remove expired keys */ 1185 if (result < 0) { 1186 if (saved_errno == EINTR) 1187 continue; 1188 fatal("select: %s", strerror(saved_errno)); 1189 } else if (result > 0) 1190 after_select(readsetp, writesetp); 1191 } 1192 /* NOTREACHED */ 1193 } 1194