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