1 /* $OpenBSD: ssh-agent.c,v 1.190 2014/07/25 21:22:03 dtucker 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 "includes.h" 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 #include <sys/resource.h> 42 #include <sys/stat.h> 43 #include <sys/socket.h> 44 #ifdef HAVE_SYS_TIME_H 45 # include <sys/time.h> 46 #endif 47 #ifdef HAVE_SYS_UN_H 48 # include <sys/un.h> 49 #endif 50 #include "openbsd-compat/sys-queue.h" 51 52 #ifdef WITH_OPENSSL 53 #include <openssl/evp.h> 54 #include "openbsd-compat/openssl-compat.h" 55 #endif 56 57 #include <errno.h> 58 #include <fcntl.h> 59 #ifdef HAVE_PATHS_H 60 # include <paths.h> 61 #endif 62 #include <signal.h> 63 #include <stdarg.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <time.h> 67 #include <string.h> 68 #include <unistd.h> 69 70 #include "xmalloc.h" 71 #include "ssh.h" 72 #include "rsa.h" 73 #include "buffer.h" 74 #include "key.h" 75 #include "authfd.h" 76 #include "compat.h" 77 #include "log.h" 78 #include "misc.h" 79 #include "digest.h" 80 81 #ifdef ENABLE_PKCS11 82 #include "ssh-pkcs11.h" 83 #endif 84 85 #if defined(HAVE_SYS_PRCTL_H) 86 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */ 87 #endif 88 89 typedef enum { 90 AUTH_UNUSED, 91 AUTH_SOCKET, 92 AUTH_CONNECTION 93 } sock_type; 94 95 typedef struct { 96 int fd; 97 sock_type type; 98 Buffer input; 99 Buffer output; 100 Buffer request; 101 } SocketEntry; 102 103 u_int sockets_alloc = 0; 104 SocketEntry *sockets = NULL; 105 106 typedef struct identity { 107 TAILQ_ENTRY(identity) next; 108 Key *key; 109 char *comment; 110 char *provider; 111 time_t death; 112 u_int confirm; 113 } Identity; 114 115 typedef struct { 116 int nentries; 117 TAILQ_HEAD(idqueue, identity) idlist; 118 } Idtab; 119 120 /* private key table, one per protocol version */ 121 Idtab idtable[3]; 122 123 int max_fd = 0; 124 125 /* pid of shell == parent of agent */ 126 pid_t parent_pid = -1; 127 time_t parent_alive_interval = 0; 128 129 /* pid of process for which cleanup_socket is applicable */ 130 pid_t cleanup_pid = 0; 131 132 /* pathname and directory for AUTH_SOCKET */ 133 char socket_name[MAXPATHLEN]; 134 char socket_dir[MAXPATHLEN]; 135 136 /* locking */ 137 int locked = 0; 138 char *lock_passwd = NULL; 139 140 extern char *__progname; 141 142 /* Default lifetime in seconds (0 == forever) */ 143 static long lifetime = 0; 144 145 static void 146 close_socket(SocketEntry *e) 147 { 148 close(e->fd); 149 e->fd = -1; 150 e->type = AUTH_UNUSED; 151 buffer_free(&e->input); 152 buffer_free(&e->output); 153 buffer_free(&e->request); 154 } 155 156 static void 157 idtab_init(void) 158 { 159 int i; 160 161 for (i = 0; i <=2; i++) { 162 TAILQ_INIT(&idtable[i].idlist); 163 idtable[i].nentries = 0; 164 } 165 } 166 167 /* return private key table for requested protocol version */ 168 static Idtab * 169 idtab_lookup(int version) 170 { 171 if (version < 1 || version > 2) 172 fatal("internal error, bad protocol version %d", version); 173 return &idtable[version]; 174 } 175 176 static void 177 free_identity(Identity *id) 178 { 179 key_free(id->key); 180 free(id->provider); 181 free(id->comment); 182 free(id); 183 } 184 185 /* return matching private key for given public key */ 186 static Identity * 187 lookup_identity(Key *key, int version) 188 { 189 Identity *id; 190 191 Idtab *tab = idtab_lookup(version); 192 TAILQ_FOREACH(id, &tab->idlist, next) { 193 if (key_equal(key, id->key)) 194 return (id); 195 } 196 return (NULL); 197 } 198 199 /* Check confirmation of keysign request */ 200 static int 201 confirm_key(Identity *id) 202 { 203 char *p; 204 int ret = -1; 205 206 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 207 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.", 208 id->comment, p)) 209 ret = 0; 210 free(p); 211 212 return (ret); 213 } 214 215 /* send list of supported public keys to 'client' */ 216 static void 217 process_request_identities(SocketEntry *e, int version) 218 { 219 Idtab *tab = idtab_lookup(version); 220 Identity *id; 221 Buffer msg; 222 223 buffer_init(&msg); 224 buffer_put_char(&msg, (version == 1) ? 225 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 226 buffer_put_int(&msg, tab->nentries); 227 TAILQ_FOREACH(id, &tab->idlist, next) { 228 if (id->key->type == KEY_RSA1) { 229 #ifdef WITH_SSH1 230 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 231 buffer_put_bignum(&msg, id->key->rsa->e); 232 buffer_put_bignum(&msg, id->key->rsa->n); 233 #endif 234 } else { 235 u_char *blob; 236 u_int blen; 237 key_to_blob(id->key, &blob, &blen); 238 buffer_put_string(&msg, blob, blen); 239 free(blob); 240 } 241 buffer_put_cstring(&msg, id->comment); 242 } 243 buffer_put_int(&e->output, buffer_len(&msg)); 244 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 245 buffer_free(&msg); 246 } 247 248 #ifdef WITH_SSH1 249 /* ssh1 only */ 250 static void 251 process_authentication_challenge1(SocketEntry *e) 252 { 253 u_char buf[32], mdbuf[16], session_id[16]; 254 u_int response_type; 255 BIGNUM *challenge; 256 Identity *id; 257 int i, len; 258 Buffer msg; 259 struct ssh_digest_ctx *md; 260 Key *key; 261 262 buffer_init(&msg); 263 key = key_new(KEY_RSA1); 264 if ((challenge = BN_new()) == NULL) 265 fatal("process_authentication_challenge1: BN_new failed"); 266 267 (void) buffer_get_int(&e->request); /* ignored */ 268 buffer_get_bignum(&e->request, key->rsa->e); 269 buffer_get_bignum(&e->request, key->rsa->n); 270 buffer_get_bignum(&e->request, challenge); 271 272 /* Only protocol 1.1 is supported */ 273 if (buffer_len(&e->request) == 0) 274 goto failure; 275 buffer_get(&e->request, session_id, 16); 276 response_type = buffer_get_int(&e->request); 277 if (response_type != 1) 278 goto failure; 279 280 id = lookup_identity(key, 1); 281 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 282 Key *private = id->key; 283 /* Decrypt the challenge using the private key. */ 284 if (rsa_private_decrypt(challenge, challenge, private->rsa) != 0) 285 goto failure; 286 287 /* The response is MD5 of decrypted challenge plus session id. */ 288 len = BN_num_bytes(challenge); 289 if (len <= 0 || len > 32) { 290 logit("process_authentication_challenge: bad challenge length %d", len); 291 goto failure; 292 } 293 memset(buf, 0, 32); 294 BN_bn2bin(challenge, buf + 32 - len); 295 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 296 ssh_digest_update(md, buf, 32) < 0 || 297 ssh_digest_update(md, session_id, 16) < 0 || 298 ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0) 299 fatal("%s: md5 failed", __func__); 300 ssh_digest_free(md); 301 302 /* Send the response. */ 303 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 304 for (i = 0; i < 16; i++) 305 buffer_put_char(&msg, mdbuf[i]); 306 goto send; 307 } 308 309 failure: 310 /* Unknown identity or protocol error. Send failure. */ 311 buffer_put_char(&msg, SSH_AGENT_FAILURE); 312 send: 313 buffer_put_int(&e->output, buffer_len(&msg)); 314 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 315 key_free(key); 316 BN_clear_free(challenge); 317 buffer_free(&msg); 318 } 319 #endif 320 321 /* ssh2 only */ 322 static void 323 process_sign_request2(SocketEntry *e) 324 { 325 u_char *blob, *data, *signature = NULL; 326 u_int blen, dlen, slen = 0; 327 extern int datafellows; 328 int odatafellows; 329 int ok = -1, flags; 330 Buffer msg; 331 Key *key; 332 333 datafellows = 0; 334 335 blob = buffer_get_string(&e->request, &blen); 336 data = buffer_get_string(&e->request, &dlen); 337 338 flags = buffer_get_int(&e->request); 339 odatafellows = datafellows; 340 if (flags & SSH_AGENT_OLD_SIGNATURE) 341 datafellows = SSH_BUG_SIGBLOB; 342 343 key = key_from_blob(blob, blen); 344 if (key != NULL) { 345 Identity *id = lookup_identity(key, 2); 346 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 347 ok = key_sign(id->key, &signature, &slen, data, dlen); 348 key_free(key); 349 } 350 buffer_init(&msg); 351 if (ok == 0) { 352 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 353 buffer_put_string(&msg, signature, slen); 354 } else { 355 buffer_put_char(&msg, SSH_AGENT_FAILURE); 356 } 357 buffer_put_int(&e->output, buffer_len(&msg)); 358 buffer_append(&e->output, buffer_ptr(&msg), 359 buffer_len(&msg)); 360 buffer_free(&msg); 361 free(data); 362 free(blob); 363 free(signature); 364 datafellows = odatafellows; 365 } 366 367 /* shared */ 368 static void 369 process_remove_identity(SocketEntry *e, int version) 370 { 371 u_int blen; 372 int success = 0; 373 Key *key = NULL; 374 u_char *blob; 375 #ifdef WITH_SSH1 376 u_int bits; 377 #endif /* WITH_SSH1 */ 378 379 switch (version) { 380 #ifdef WITH_SSH1 381 case 1: 382 key = key_new(KEY_RSA1); 383 bits = buffer_get_int(&e->request); 384 buffer_get_bignum(&e->request, key->rsa->e); 385 buffer_get_bignum(&e->request, key->rsa->n); 386 387 if (bits != key_size(key)) 388 logit("Warning: identity keysize mismatch: actual %u, announced %u", 389 key_size(key), bits); 390 break; 391 #endif /* WITH_SSH1 */ 392 case 2: 393 blob = buffer_get_string(&e->request, &blen); 394 key = key_from_blob(blob, blen); 395 free(blob); 396 break; 397 } 398 if (key != NULL) { 399 Identity *id = lookup_identity(key, version); 400 if (id != NULL) { 401 /* 402 * We have this key. Free the old key. Since we 403 * don't want to leave empty slots in the middle of 404 * the array, we actually free the key there and move 405 * all the entries between the empty slot and the end 406 * of the array. 407 */ 408 Idtab *tab = idtab_lookup(version); 409 if (tab->nentries < 1) 410 fatal("process_remove_identity: " 411 "internal error: tab->nentries %d", 412 tab->nentries); 413 TAILQ_REMOVE(&tab->idlist, id, next); 414 free_identity(id); 415 tab->nentries--; 416 success = 1; 417 } 418 key_free(key); 419 } 420 buffer_put_int(&e->output, 1); 421 buffer_put_char(&e->output, 422 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 423 } 424 425 static void 426 process_remove_all_identities(SocketEntry *e, int version) 427 { 428 Idtab *tab = idtab_lookup(version); 429 Identity *id; 430 431 /* Loop over all identities and clear the keys. */ 432 for (id = TAILQ_FIRST(&tab->idlist); id; 433 id = TAILQ_FIRST(&tab->idlist)) { 434 TAILQ_REMOVE(&tab->idlist, id, next); 435 free_identity(id); 436 } 437 438 /* Mark that there are no identities. */ 439 tab->nentries = 0; 440 441 /* Send success. */ 442 buffer_put_int(&e->output, 1); 443 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 444 } 445 446 /* removes expired keys and returns number of seconds until the next expiry */ 447 static time_t 448 reaper(void) 449 { 450 time_t deadline = 0, now = monotime(); 451 Identity *id, *nxt; 452 int version; 453 Idtab *tab; 454 455 for (version = 1; version < 3; version++) { 456 tab = idtab_lookup(version); 457 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 458 nxt = TAILQ_NEXT(id, next); 459 if (id->death == 0) 460 continue; 461 if (now >= id->death) { 462 debug("expiring key '%s'", id->comment); 463 TAILQ_REMOVE(&tab->idlist, id, next); 464 free_identity(id); 465 tab->nentries--; 466 } else 467 deadline = (deadline == 0) ? id->death : 468 MIN(deadline, id->death); 469 } 470 } 471 if (deadline == 0 || deadline <= now) 472 return 0; 473 else 474 return (deadline - now); 475 } 476 477 static void 478 process_add_identity(SocketEntry *e, int version) 479 { 480 Idtab *tab = idtab_lookup(version); 481 Identity *id; 482 int type, success = 0, confirm = 0; 483 char *comment; 484 time_t death = 0; 485 Key *k = NULL; 486 487 switch (version) { 488 #ifdef WITH_SSH1 489 case 1: 490 k = key_new_private(KEY_RSA1); 491 (void) buffer_get_int(&e->request); /* ignored */ 492 buffer_get_bignum(&e->request, k->rsa->n); 493 buffer_get_bignum(&e->request, k->rsa->e); 494 buffer_get_bignum(&e->request, k->rsa->d); 495 buffer_get_bignum(&e->request, k->rsa->iqmp); 496 497 /* SSH and SSL have p and q swapped */ 498 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 499 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 500 501 /* Generate additional parameters */ 502 if (rsa_generate_additional_parameters(k->rsa) != 0) 503 fatal("%s: rsa_generate_additional_parameters " 504 "error", __func__); 505 506 /* enable blinding */ 507 if (RSA_blinding_on(k->rsa, NULL) != 1) { 508 error("process_add_identity: RSA_blinding_on failed"); 509 key_free(k); 510 goto send; 511 } 512 break; 513 #endif /* WITH_SSH1 */ 514 case 2: 515 k = key_private_deserialize(&e->request); 516 if (k == NULL) { 517 buffer_clear(&e->request); 518 goto send; 519 } 520 break; 521 } 522 if (k == NULL) 523 goto send; 524 comment = buffer_get_string(&e->request, NULL); 525 526 while (buffer_len(&e->request)) { 527 switch ((type = buffer_get_char(&e->request))) { 528 case SSH_AGENT_CONSTRAIN_LIFETIME: 529 death = monotime() + buffer_get_int(&e->request); 530 break; 531 case SSH_AGENT_CONSTRAIN_CONFIRM: 532 confirm = 1; 533 break; 534 default: 535 error("process_add_identity: " 536 "Unknown constraint type %d", type); 537 free(comment); 538 key_free(k); 539 goto send; 540 } 541 } 542 success = 1; 543 if (lifetime && !death) 544 death = monotime() + lifetime; 545 if ((id = lookup_identity(k, version)) == NULL) { 546 id = xcalloc(1, sizeof(Identity)); 547 id->key = k; 548 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 549 /* Increment the number of identities. */ 550 tab->nentries++; 551 } else { 552 key_free(k); 553 free(id->comment); 554 } 555 id->comment = comment; 556 id->death = death; 557 id->confirm = confirm; 558 send: 559 buffer_put_int(&e->output, 1); 560 buffer_put_char(&e->output, 561 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 562 } 563 564 /* XXX todo: encrypt sensitive data with passphrase */ 565 static void 566 process_lock_agent(SocketEntry *e, int lock) 567 { 568 int success = 0; 569 char *passwd; 570 571 passwd = buffer_get_string(&e->request, NULL); 572 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 573 locked = 0; 574 explicit_bzero(lock_passwd, strlen(lock_passwd)); 575 free(lock_passwd); 576 lock_passwd = NULL; 577 success = 1; 578 } else if (!locked && lock) { 579 locked = 1; 580 lock_passwd = xstrdup(passwd); 581 success = 1; 582 } 583 explicit_bzero(passwd, strlen(passwd)); 584 free(passwd); 585 586 buffer_put_int(&e->output, 1); 587 buffer_put_char(&e->output, 588 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 589 } 590 591 static void 592 no_identities(SocketEntry *e, u_int type) 593 { 594 Buffer msg; 595 596 buffer_init(&msg); 597 buffer_put_char(&msg, 598 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 599 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 600 buffer_put_int(&msg, 0); 601 buffer_put_int(&e->output, buffer_len(&msg)); 602 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 603 buffer_free(&msg); 604 } 605 606 #ifdef ENABLE_PKCS11 607 static void 608 process_add_smartcard_key(SocketEntry *e) 609 { 610 char *provider = NULL, *pin; 611 int i, type, version, count = 0, success = 0, confirm = 0; 612 time_t death = 0; 613 Key **keys = NULL, *k; 614 Identity *id; 615 Idtab *tab; 616 617 provider = buffer_get_string(&e->request, NULL); 618 pin = buffer_get_string(&e->request, NULL); 619 620 while (buffer_len(&e->request)) { 621 switch ((type = buffer_get_char(&e->request))) { 622 case SSH_AGENT_CONSTRAIN_LIFETIME: 623 death = monotime() + buffer_get_int(&e->request); 624 break; 625 case SSH_AGENT_CONSTRAIN_CONFIRM: 626 confirm = 1; 627 break; 628 default: 629 error("process_add_smartcard_key: " 630 "Unknown constraint type %d", type); 631 goto send; 632 } 633 } 634 if (lifetime && !death) 635 death = monotime() + lifetime; 636 637 count = pkcs11_add_provider(provider, pin, &keys); 638 for (i = 0; i < count; i++) { 639 k = keys[i]; 640 version = k->type == KEY_RSA1 ? 1 : 2; 641 tab = idtab_lookup(version); 642 if (lookup_identity(k, version) == NULL) { 643 id = xcalloc(1, sizeof(Identity)); 644 id->key = k; 645 id->provider = xstrdup(provider); 646 id->comment = xstrdup(provider); /* XXX */ 647 id->death = death; 648 id->confirm = confirm; 649 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 650 tab->nentries++; 651 success = 1; 652 } else { 653 key_free(k); 654 } 655 keys[i] = NULL; 656 } 657 send: 658 free(pin); 659 free(provider); 660 free(keys); 661 buffer_put_int(&e->output, 1); 662 buffer_put_char(&e->output, 663 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 664 } 665 666 static void 667 process_remove_smartcard_key(SocketEntry *e) 668 { 669 char *provider = NULL, *pin = NULL; 670 int version, success = 0; 671 Identity *id, *nxt; 672 Idtab *tab; 673 674 provider = buffer_get_string(&e->request, NULL); 675 pin = buffer_get_string(&e->request, NULL); 676 free(pin); 677 678 for (version = 1; version < 3; version++) { 679 tab = idtab_lookup(version); 680 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 681 nxt = TAILQ_NEXT(id, next); 682 /* Skip file--based keys */ 683 if (id->provider == NULL) 684 continue; 685 if (!strcmp(provider, id->provider)) { 686 TAILQ_REMOVE(&tab->idlist, id, next); 687 free_identity(id); 688 tab->nentries--; 689 } 690 } 691 } 692 if (pkcs11_del_provider(provider) == 0) 693 success = 1; 694 else 695 error("process_remove_smartcard_key:" 696 " pkcs11_del_provider failed"); 697 free(provider); 698 buffer_put_int(&e->output, 1); 699 buffer_put_char(&e->output, 700 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 701 } 702 #endif /* ENABLE_PKCS11 */ 703 704 /* dispatch incoming messages */ 705 706 static void 707 process_message(SocketEntry *e) 708 { 709 u_int msg_len, type; 710 u_char *cp; 711 712 if (buffer_len(&e->input) < 5) 713 return; /* Incomplete message. */ 714 cp = buffer_ptr(&e->input); 715 msg_len = get_u32(cp); 716 if (msg_len > 256 * 1024) { 717 close_socket(e); 718 return; 719 } 720 if (buffer_len(&e->input) < msg_len + 4) 721 return; 722 723 /* move the current input to e->request */ 724 buffer_consume(&e->input, 4); 725 buffer_clear(&e->request); 726 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 727 buffer_consume(&e->input, msg_len); 728 type = buffer_get_char(&e->request); 729 730 /* check wheter agent is locked */ 731 if (locked && type != SSH_AGENTC_UNLOCK) { 732 buffer_clear(&e->request); 733 switch (type) { 734 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 735 case SSH2_AGENTC_REQUEST_IDENTITIES: 736 /* send empty lists */ 737 no_identities(e, type); 738 break; 739 default: 740 /* send a fail message for all other request types */ 741 buffer_put_int(&e->output, 1); 742 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 743 } 744 return; 745 } 746 747 debug("type %d", type); 748 switch (type) { 749 case SSH_AGENTC_LOCK: 750 case SSH_AGENTC_UNLOCK: 751 process_lock_agent(e, type == SSH_AGENTC_LOCK); 752 break; 753 #ifdef WITH_SSH1 754 /* ssh1 */ 755 case SSH_AGENTC_RSA_CHALLENGE: 756 process_authentication_challenge1(e); 757 break; 758 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 759 process_request_identities(e, 1); 760 break; 761 case SSH_AGENTC_ADD_RSA_IDENTITY: 762 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 763 process_add_identity(e, 1); 764 break; 765 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 766 process_remove_identity(e, 1); 767 break; 768 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 769 process_remove_all_identities(e, 1); 770 break; 771 #endif 772 /* ssh2 */ 773 case SSH2_AGENTC_SIGN_REQUEST: 774 process_sign_request2(e); 775 break; 776 case SSH2_AGENTC_REQUEST_IDENTITIES: 777 process_request_identities(e, 2); 778 break; 779 case SSH2_AGENTC_ADD_IDENTITY: 780 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 781 process_add_identity(e, 2); 782 break; 783 case SSH2_AGENTC_REMOVE_IDENTITY: 784 process_remove_identity(e, 2); 785 break; 786 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 787 process_remove_all_identities(e, 2); 788 break; 789 #ifdef ENABLE_PKCS11 790 case SSH_AGENTC_ADD_SMARTCARD_KEY: 791 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 792 process_add_smartcard_key(e); 793 break; 794 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 795 process_remove_smartcard_key(e); 796 break; 797 #endif /* ENABLE_PKCS11 */ 798 default: 799 /* Unknown message. Respond with failure. */ 800 error("Unknown message %d", type); 801 buffer_clear(&e->request); 802 buffer_put_int(&e->output, 1); 803 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 804 break; 805 } 806 } 807 808 static void 809 new_socket(sock_type type, int fd) 810 { 811 u_int i, old_alloc, new_alloc; 812 813 set_nonblock(fd); 814 815 if (fd > max_fd) 816 max_fd = fd; 817 818 for (i = 0; i < sockets_alloc; i++) 819 if (sockets[i].type == AUTH_UNUSED) { 820 sockets[i].fd = fd; 821 buffer_init(&sockets[i].input); 822 buffer_init(&sockets[i].output); 823 buffer_init(&sockets[i].request); 824 sockets[i].type = type; 825 return; 826 } 827 old_alloc = sockets_alloc; 828 new_alloc = sockets_alloc + 10; 829 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0])); 830 for (i = old_alloc; i < new_alloc; i++) 831 sockets[i].type = AUTH_UNUSED; 832 sockets_alloc = new_alloc; 833 sockets[old_alloc].fd = fd; 834 buffer_init(&sockets[old_alloc].input); 835 buffer_init(&sockets[old_alloc].output); 836 buffer_init(&sockets[old_alloc].request); 837 sockets[old_alloc].type = type; 838 } 839 840 static int 841 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 842 struct timeval **tvpp) 843 { 844 u_int i, sz; 845 int n = 0; 846 static struct timeval tv; 847 time_t deadline; 848 849 for (i = 0; i < sockets_alloc; i++) { 850 switch (sockets[i].type) { 851 case AUTH_SOCKET: 852 case AUTH_CONNECTION: 853 n = MAX(n, sockets[i].fd); 854 break; 855 case AUTH_UNUSED: 856 break; 857 default: 858 fatal("Unknown socket type %d", sockets[i].type); 859 break; 860 } 861 } 862 863 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 864 if (*fdrp == NULL || sz > *nallocp) { 865 free(*fdrp); 866 free(*fdwp); 867 *fdrp = xmalloc(sz); 868 *fdwp = xmalloc(sz); 869 *nallocp = sz; 870 } 871 if (n < *fdl) 872 debug("XXX shrink: %d < %d", n, *fdl); 873 *fdl = n; 874 memset(*fdrp, 0, sz); 875 memset(*fdwp, 0, sz); 876 877 for (i = 0; i < sockets_alloc; i++) { 878 switch (sockets[i].type) { 879 case AUTH_SOCKET: 880 case AUTH_CONNECTION: 881 FD_SET(sockets[i].fd, *fdrp); 882 if (buffer_len(&sockets[i].output) > 0) 883 FD_SET(sockets[i].fd, *fdwp); 884 break; 885 default: 886 break; 887 } 888 } 889 deadline = reaper(); 890 if (parent_alive_interval != 0) 891 deadline = (deadline == 0) ? parent_alive_interval : 892 MIN(deadline, parent_alive_interval); 893 if (deadline == 0) { 894 *tvpp = NULL; 895 } else { 896 tv.tv_sec = deadline; 897 tv.tv_usec = 0; 898 *tvpp = &tv; 899 } 900 return (1); 901 } 902 903 static void 904 after_select(fd_set *readset, fd_set *writeset) 905 { 906 struct sockaddr_un sunaddr; 907 socklen_t slen; 908 char buf[1024]; 909 int len, sock; 910 u_int i, orig_alloc; 911 uid_t euid; 912 gid_t egid; 913 914 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++) 915 switch (sockets[i].type) { 916 case AUTH_UNUSED: 917 break; 918 case AUTH_SOCKET: 919 if (FD_ISSET(sockets[i].fd, readset)) { 920 slen = sizeof(sunaddr); 921 sock = accept(sockets[i].fd, 922 (struct sockaddr *)&sunaddr, &slen); 923 if (sock < 0) { 924 error("accept from AUTH_SOCKET: %s", 925 strerror(errno)); 926 break; 927 } 928 if (getpeereid(sock, &euid, &egid) < 0) { 929 error("getpeereid %d failed: %s", 930 sock, strerror(errno)); 931 close(sock); 932 break; 933 } 934 if ((euid != 0) && (getuid() != euid)) { 935 error("uid mismatch: " 936 "peer euid %u != uid %u", 937 (u_int) euid, (u_int) getuid()); 938 close(sock); 939 break; 940 } 941 new_socket(AUTH_CONNECTION, sock); 942 } 943 break; 944 case AUTH_CONNECTION: 945 if (buffer_len(&sockets[i].output) > 0 && 946 FD_ISSET(sockets[i].fd, writeset)) { 947 len = write(sockets[i].fd, 948 buffer_ptr(&sockets[i].output), 949 buffer_len(&sockets[i].output)); 950 if (len == -1 && (errno == EAGAIN || 951 errno == EWOULDBLOCK || 952 errno == EINTR)) 953 continue; 954 if (len <= 0) { 955 close_socket(&sockets[i]); 956 break; 957 } 958 buffer_consume(&sockets[i].output, len); 959 } 960 if (FD_ISSET(sockets[i].fd, readset)) { 961 len = read(sockets[i].fd, buf, sizeof(buf)); 962 if (len == -1 && (errno == EAGAIN || 963 errno == EWOULDBLOCK || 964 errno == EINTR)) 965 continue; 966 if (len <= 0) { 967 close_socket(&sockets[i]); 968 break; 969 } 970 buffer_append(&sockets[i].input, buf, len); 971 explicit_bzero(buf, sizeof(buf)); 972 process_message(&sockets[i]); 973 } 974 break; 975 default: 976 fatal("Unknown type %d", sockets[i].type); 977 } 978 } 979 980 static void 981 cleanup_socket(void) 982 { 983 if (cleanup_pid != 0 && getpid() != cleanup_pid) 984 return; 985 debug("%s: cleanup", __func__); 986 if (socket_name[0]) 987 unlink(socket_name); 988 if (socket_dir[0]) 989 rmdir(socket_dir); 990 } 991 992 void 993 cleanup_exit(int i) 994 { 995 cleanup_socket(); 996 _exit(i); 997 } 998 999 /*ARGSUSED*/ 1000 static void 1001 cleanup_handler(int sig) 1002 { 1003 cleanup_socket(); 1004 #ifdef ENABLE_PKCS11 1005 pkcs11_terminate(); 1006 #endif 1007 _exit(2); 1008 } 1009 1010 static void 1011 check_parent_exists(void) 1012 { 1013 /* 1014 * If our parent has exited then getppid() will return (pid_t)1, 1015 * so testing for that should be safe. 1016 */ 1017 if (parent_pid != -1 && getppid() != parent_pid) { 1018 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1019 cleanup_socket(); 1020 _exit(2); 1021 } 1022 } 1023 1024 static void 1025 usage(void) 1026 { 1027 fprintf(stderr, 1028 "usage: ssh-agent [-c | -s] [-d] [-a bind_address] [-t life]\n" 1029 " [command [arg ...]]\n" 1030 " ssh-agent [-c | -s] -k\n"); 1031 exit(1); 1032 } 1033 1034 int 1035 main(int ac, char **av) 1036 { 1037 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1038 int sock, fd, ch, result, saved_errno; 1039 u_int nalloc; 1040 char *shell, *format, *pidstr, *agentsocket = NULL; 1041 fd_set *readsetp = NULL, *writesetp = NULL; 1042 #ifdef HAVE_SETRLIMIT 1043 struct rlimit rlim; 1044 #endif 1045 extern int optind; 1046 extern char *optarg; 1047 pid_t pid; 1048 char pidstrbuf[1 + 3 * sizeof pid]; 1049 struct timeval *tvp = NULL; 1050 size_t len; 1051 mode_t prev_mask; 1052 1053 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1054 sanitise_stdfd(); 1055 1056 /* drop */ 1057 setegid(getgid()); 1058 setgid(getgid()); 1059 setuid(geteuid()); 1060 1061 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) 1062 /* Disable ptrace on Linux without sgid bit */ 1063 prctl(PR_SET_DUMPABLE, 0); 1064 #endif 1065 1066 #ifdef WITH_OPENSSL 1067 OpenSSL_add_all_algorithms(); 1068 #endif 1069 1070 __progname = ssh_get_progname(av[0]); 1071 seed_rng(); 1072 1073 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) { 1074 switch (ch) { 1075 case 'c': 1076 if (s_flag) 1077 usage(); 1078 c_flag++; 1079 break; 1080 case 'k': 1081 k_flag++; 1082 break; 1083 case 's': 1084 if (c_flag) 1085 usage(); 1086 s_flag++; 1087 break; 1088 case 'd': 1089 if (d_flag) 1090 usage(); 1091 d_flag++; 1092 break; 1093 case 'a': 1094 agentsocket = optarg; 1095 break; 1096 case 't': 1097 if ((lifetime = convtime(optarg)) == -1) { 1098 fprintf(stderr, "Invalid lifetime\n"); 1099 usage(); 1100 } 1101 break; 1102 default: 1103 usage(); 1104 } 1105 } 1106 ac -= optind; 1107 av += optind; 1108 1109 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1110 usage(); 1111 1112 if (ac == 0 && !c_flag && !s_flag) { 1113 shell = getenv("SHELL"); 1114 if (shell != NULL && (len = strlen(shell)) > 2 && 1115 strncmp(shell + len - 3, "csh", 3) == 0) 1116 c_flag = 1; 1117 } 1118 if (k_flag) { 1119 const char *errstr = NULL; 1120 1121 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1122 if (pidstr == NULL) { 1123 fprintf(stderr, "%s not set, cannot kill agent\n", 1124 SSH_AGENTPID_ENV_NAME); 1125 exit(1); 1126 } 1127 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1128 if (errstr) { 1129 fprintf(stderr, 1130 "%s=\"%s\", which is not a good PID: %s\n", 1131 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1132 exit(1); 1133 } 1134 if (kill(pid, SIGTERM) == -1) { 1135 perror("kill"); 1136 exit(1); 1137 } 1138 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1139 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1140 printf(format, SSH_AGENTPID_ENV_NAME); 1141 printf("echo Agent pid %ld killed;\n", (long)pid); 1142 exit(0); 1143 } 1144 parent_pid = getpid(); 1145 1146 if (agentsocket == NULL) { 1147 /* Create private directory for agent socket */ 1148 mktemp_proto(socket_dir, sizeof(socket_dir)); 1149 if (mkdtemp(socket_dir) == NULL) { 1150 perror("mkdtemp: private socket dir"); 1151 exit(1); 1152 } 1153 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1154 (long)parent_pid); 1155 } else { 1156 /* Try to use specified agent socket */ 1157 socket_dir[0] = '\0'; 1158 strlcpy(socket_name, agentsocket, sizeof socket_name); 1159 } 1160 1161 /* 1162 * Create socket early so it will exist before command gets run from 1163 * the parent. 1164 */ 1165 prev_mask = umask(0177); 1166 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1167 if (sock < 0) { 1168 /* XXX - unix_listener() calls error() not perror() */ 1169 *socket_name = '\0'; /* Don't unlink any existing file */ 1170 cleanup_exit(1); 1171 } 1172 umask(prev_mask); 1173 1174 /* 1175 * Fork, and have the parent execute the command, if any, or present 1176 * the socket data. The child continues as the authentication agent. 1177 */ 1178 if (d_flag) { 1179 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1180 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1181 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1182 SSH_AUTHSOCKET_ENV_NAME); 1183 printf("echo Agent pid %ld;\n", (long)parent_pid); 1184 goto skip; 1185 } 1186 pid = fork(); 1187 if (pid == -1) { 1188 perror("fork"); 1189 cleanup_exit(1); 1190 } 1191 if (pid != 0) { /* Parent - execute the given command. */ 1192 close(sock); 1193 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1194 if (ac == 0) { 1195 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1196 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1197 SSH_AUTHSOCKET_ENV_NAME); 1198 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1199 SSH_AGENTPID_ENV_NAME); 1200 printf("echo Agent pid %ld;\n", (long)pid); 1201 exit(0); 1202 } 1203 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1204 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1205 perror("setenv"); 1206 exit(1); 1207 } 1208 execvp(av[0], av); 1209 perror(av[0]); 1210 exit(1); 1211 } 1212 /* child */ 1213 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1214 1215 if (setsid() == -1) { 1216 error("setsid: %s", strerror(errno)); 1217 cleanup_exit(1); 1218 } 1219 1220 (void)chdir("/"); 1221 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1222 /* XXX might close listen socket */ 1223 (void)dup2(fd, STDIN_FILENO); 1224 (void)dup2(fd, STDOUT_FILENO); 1225 (void)dup2(fd, STDERR_FILENO); 1226 if (fd > 2) 1227 close(fd); 1228 } 1229 1230 #ifdef HAVE_SETRLIMIT 1231 /* deny core dumps, since memory contains unencrypted private keys */ 1232 rlim.rlim_cur = rlim.rlim_max = 0; 1233 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1234 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1235 cleanup_exit(1); 1236 } 1237 #endif 1238 1239 skip: 1240 1241 cleanup_pid = getpid(); 1242 1243 #ifdef ENABLE_PKCS11 1244 pkcs11_init(0); 1245 #endif 1246 new_socket(AUTH_SOCKET, sock); 1247 if (ac > 0) 1248 parent_alive_interval = 10; 1249 idtab_init(); 1250 signal(SIGPIPE, SIG_IGN); 1251 signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN); 1252 signal(SIGHUP, cleanup_handler); 1253 signal(SIGTERM, cleanup_handler); 1254 nalloc = 0; 1255 1256 while (1) { 1257 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp); 1258 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp); 1259 saved_errno = errno; 1260 if (parent_alive_interval != 0) 1261 check_parent_exists(); 1262 (void) reaper(); /* remove expired keys */ 1263 if (result < 0) { 1264 if (saved_errno == EINTR) 1265 continue; 1266 fatal("select: %s", strerror(saved_errno)); 1267 } else if (result > 0) 1268 after_select(readsetp, writesetp); 1269 } 1270 /* NOTREACHED */ 1271 } 1272