1 /* $OpenBSD: ssh-agent.c,v 1.183 2014/02/02 03:44:31 djm Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * The authentication agent program. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include "includes.h" 39 __RCSID("$FreeBSD$"); 40 41 #include <sys/types.h> 42 #include <sys/param.h> 43 #include <sys/resource.h> 44 #include <sys/stat.h> 45 #include <sys/socket.h> 46 #ifdef HAVE_SYS_TIME_H 47 # include <sys/time.h> 48 #endif 49 #ifdef HAVE_SYS_UN_H 50 # include <sys/un.h> 51 #endif 52 #include "openbsd-compat/sys-queue.h" 53 54 #include <openssl/evp.h> 55 #include "openbsd-compat/openssl-compat.h" 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 /* pathname and directory for AUTH_SOCKET */ 130 char socket_name[MAXPATHLEN]; 131 char socket_dir[MAXPATHLEN]; 132 133 /* locking */ 134 int locked = 0; 135 char *lock_passwd = NULL; 136 137 extern char *__progname; 138 139 /* Default lifetime in seconds (0 == forever) */ 140 static long lifetime = 0; 141 142 /* 143 * Client connection count; incremented in new_socket() and decremented in 144 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 145 * normally initialized to 1, it will never reach 0. However, if the -x 146 * option is specified, it is initialized to 0 in main(); in that case, 147 * ssh-agent will exit as soon as it has had at least one client but no 148 * longer has any. 149 */ 150 static int xcount = 1; 151 152 static void 153 close_socket(SocketEntry *e) 154 { 155 int last = 0; 156 157 if (e->type == AUTH_CONNECTION) { 158 debug("xcount %d -> %d", xcount, xcount - 1); 159 if (--xcount == 0) 160 last = 1; 161 } 162 close(e->fd); 163 e->fd = -1; 164 e->type = AUTH_UNUSED; 165 buffer_free(&e->input); 166 buffer_free(&e->output); 167 buffer_free(&e->request); 168 if (last) 169 cleanup_exit(0); 170 } 171 172 static void 173 idtab_init(void) 174 { 175 int i; 176 177 for (i = 0; i <=2; i++) { 178 TAILQ_INIT(&idtable[i].idlist); 179 idtable[i].nentries = 0; 180 } 181 } 182 183 /* return private key table for requested protocol version */ 184 static Idtab * 185 idtab_lookup(int version) 186 { 187 if (version < 1 || version > 2) 188 fatal("internal error, bad protocol version %d", version); 189 return &idtable[version]; 190 } 191 192 static void 193 free_identity(Identity *id) 194 { 195 key_free(id->key); 196 free(id->provider); 197 free(id->comment); 198 free(id); 199 } 200 201 /* return matching private key for given public key */ 202 static Identity * 203 lookup_identity(Key *key, int version) 204 { 205 Identity *id; 206 207 Idtab *tab = idtab_lookup(version); 208 TAILQ_FOREACH(id, &tab->idlist, next) { 209 if (key_equal(key, id->key)) 210 return (id); 211 } 212 return (NULL); 213 } 214 215 /* Check confirmation of keysign request */ 216 static int 217 confirm_key(Identity *id) 218 { 219 char *p; 220 int ret = -1; 221 222 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 223 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.", 224 id->comment, p)) 225 ret = 0; 226 free(p); 227 228 return (ret); 229 } 230 231 /* send list of supported public keys to 'client' */ 232 static void 233 process_request_identities(SocketEntry *e, int version) 234 { 235 Idtab *tab = idtab_lookup(version); 236 Identity *id; 237 Buffer msg; 238 239 buffer_init(&msg); 240 buffer_put_char(&msg, (version == 1) ? 241 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 242 buffer_put_int(&msg, tab->nentries); 243 TAILQ_FOREACH(id, &tab->idlist, next) { 244 if (id->key->type == KEY_RSA1) { 245 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 246 buffer_put_bignum(&msg, id->key->rsa->e); 247 buffer_put_bignum(&msg, id->key->rsa->n); 248 } else { 249 u_char *blob; 250 u_int blen; 251 key_to_blob(id->key, &blob, &blen); 252 buffer_put_string(&msg, blob, blen); 253 free(blob); 254 } 255 buffer_put_cstring(&msg, id->comment); 256 } 257 buffer_put_int(&e->output, buffer_len(&msg)); 258 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 259 buffer_free(&msg); 260 } 261 262 /* ssh1 only */ 263 static void 264 process_authentication_challenge1(SocketEntry *e) 265 { 266 u_char buf[32], mdbuf[16], session_id[16]; 267 u_int response_type; 268 BIGNUM *challenge; 269 Identity *id; 270 int i, len; 271 Buffer msg; 272 struct ssh_digest_ctx *md; 273 Key *key; 274 275 buffer_init(&msg); 276 key = key_new(KEY_RSA1); 277 if ((challenge = BN_new()) == NULL) 278 fatal("process_authentication_challenge1: BN_new failed"); 279 280 (void) buffer_get_int(&e->request); /* ignored */ 281 buffer_get_bignum(&e->request, key->rsa->e); 282 buffer_get_bignum(&e->request, key->rsa->n); 283 buffer_get_bignum(&e->request, challenge); 284 285 /* Only protocol 1.1 is supported */ 286 if (buffer_len(&e->request) == 0) 287 goto failure; 288 buffer_get(&e->request, session_id, 16); 289 response_type = buffer_get_int(&e->request); 290 if (response_type != 1) 291 goto failure; 292 293 id = lookup_identity(key, 1); 294 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 295 Key *private = id->key; 296 /* Decrypt the challenge using the private key. */ 297 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 298 goto failure; 299 300 /* The response is MD5 of decrypted challenge plus session id. */ 301 len = BN_num_bytes(challenge); 302 if (len <= 0 || len > 32) { 303 logit("process_authentication_challenge: bad challenge length %d", len); 304 goto failure; 305 } 306 memset(buf, 0, 32); 307 BN_bn2bin(challenge, buf + 32 - len); 308 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 309 ssh_digest_update(md, buf, 32) < 0 || 310 ssh_digest_update(md, session_id, 16) < 0 || 311 ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0) 312 fatal("%s: md5 failed", __func__); 313 ssh_digest_free(md); 314 315 /* Send the response. */ 316 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 317 for (i = 0; i < 16; i++) 318 buffer_put_char(&msg, mdbuf[i]); 319 goto send; 320 } 321 322 failure: 323 /* Unknown identity or protocol error. Send failure. */ 324 buffer_put_char(&msg, SSH_AGENT_FAILURE); 325 send: 326 buffer_put_int(&e->output, buffer_len(&msg)); 327 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 328 key_free(key); 329 BN_clear_free(challenge); 330 buffer_free(&msg); 331 } 332 333 /* ssh2 only */ 334 static void 335 process_sign_request2(SocketEntry *e) 336 { 337 u_char *blob, *data, *signature = NULL; 338 u_int blen, dlen, slen = 0; 339 extern int datafellows; 340 int odatafellows; 341 int ok = -1, flags; 342 Buffer msg; 343 Key *key; 344 345 datafellows = 0; 346 347 blob = buffer_get_string(&e->request, &blen); 348 data = buffer_get_string(&e->request, &dlen); 349 350 flags = buffer_get_int(&e->request); 351 odatafellows = datafellows; 352 if (flags & SSH_AGENT_OLD_SIGNATURE) 353 datafellows = SSH_BUG_SIGBLOB; 354 355 key = key_from_blob(blob, blen); 356 if (key != NULL) { 357 Identity *id = lookup_identity(key, 2); 358 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 359 ok = key_sign(id->key, &signature, &slen, data, dlen); 360 key_free(key); 361 } 362 buffer_init(&msg); 363 if (ok == 0) { 364 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 365 buffer_put_string(&msg, signature, slen); 366 } else { 367 buffer_put_char(&msg, SSH_AGENT_FAILURE); 368 } 369 buffer_put_int(&e->output, buffer_len(&msg)); 370 buffer_append(&e->output, buffer_ptr(&msg), 371 buffer_len(&msg)); 372 buffer_free(&msg); 373 free(data); 374 free(blob); 375 free(signature); 376 datafellows = odatafellows; 377 } 378 379 /* shared */ 380 static void 381 process_remove_identity(SocketEntry *e, int version) 382 { 383 u_int blen, bits; 384 int success = 0; 385 Key *key = NULL; 386 u_char *blob; 387 388 switch (version) { 389 case 1: 390 key = key_new(KEY_RSA1); 391 bits = buffer_get_int(&e->request); 392 buffer_get_bignum(&e->request, key->rsa->e); 393 buffer_get_bignum(&e->request, key->rsa->n); 394 395 if (bits != key_size(key)) 396 logit("Warning: identity keysize mismatch: actual %u, announced %u", 397 key_size(key), bits); 398 break; 399 case 2: 400 blob = buffer_get_string(&e->request, &blen); 401 key = key_from_blob(blob, blen); 402 free(blob); 403 break; 404 } 405 if (key != NULL) { 406 Identity *id = lookup_identity(key, version); 407 if (id != NULL) { 408 /* 409 * We have this key. Free the old key. Since we 410 * don't want to leave empty slots in the middle of 411 * the array, we actually free the key there and move 412 * all the entries between the empty slot and the end 413 * of the array. 414 */ 415 Idtab *tab = idtab_lookup(version); 416 if (tab->nentries < 1) 417 fatal("process_remove_identity: " 418 "internal error: tab->nentries %d", 419 tab->nentries); 420 TAILQ_REMOVE(&tab->idlist, id, next); 421 free_identity(id); 422 tab->nentries--; 423 success = 1; 424 } 425 key_free(key); 426 } 427 buffer_put_int(&e->output, 1); 428 buffer_put_char(&e->output, 429 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 430 } 431 432 static void 433 process_remove_all_identities(SocketEntry *e, int version) 434 { 435 Idtab *tab = idtab_lookup(version); 436 Identity *id; 437 438 /* Loop over all identities and clear the keys. */ 439 for (id = TAILQ_FIRST(&tab->idlist); id; 440 id = TAILQ_FIRST(&tab->idlist)) { 441 TAILQ_REMOVE(&tab->idlist, id, next); 442 free_identity(id); 443 } 444 445 /* Mark that there are no identities. */ 446 tab->nentries = 0; 447 448 /* Send success. */ 449 buffer_put_int(&e->output, 1); 450 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 451 } 452 453 /* removes expired keys and returns number of seconds until the next expiry */ 454 static time_t 455 reaper(void) 456 { 457 time_t deadline = 0, now = monotime(); 458 Identity *id, *nxt; 459 int version; 460 Idtab *tab; 461 462 for (version = 1; version < 3; version++) { 463 tab = idtab_lookup(version); 464 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 465 nxt = TAILQ_NEXT(id, next); 466 if (id->death == 0) 467 continue; 468 if (now >= id->death) { 469 debug("expiring key '%s'", id->comment); 470 TAILQ_REMOVE(&tab->idlist, id, next); 471 free_identity(id); 472 tab->nentries--; 473 } else 474 deadline = (deadline == 0) ? id->death : 475 MIN(deadline, id->death); 476 } 477 } 478 if (deadline == 0 || deadline <= now) 479 return 0; 480 else 481 return (deadline - now); 482 } 483 484 static void 485 process_add_identity(SocketEntry *e, int version) 486 { 487 Idtab *tab = idtab_lookup(version); 488 Identity *id; 489 int type, success = 0, confirm = 0; 490 char *comment; 491 time_t death = 0; 492 Key *k = NULL; 493 494 switch (version) { 495 case 1: 496 k = key_new_private(KEY_RSA1); 497 (void) buffer_get_int(&e->request); /* ignored */ 498 buffer_get_bignum(&e->request, k->rsa->n); 499 buffer_get_bignum(&e->request, k->rsa->e); 500 buffer_get_bignum(&e->request, k->rsa->d); 501 buffer_get_bignum(&e->request, k->rsa->iqmp); 502 503 /* SSH and SSL have p and q swapped */ 504 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 505 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 506 507 /* Generate additional parameters */ 508 rsa_generate_additional_parameters(k->rsa); 509 510 /* enable blinding */ 511 if (RSA_blinding_on(k->rsa, NULL) != 1) { 512 error("process_add_identity: RSA_blinding_on failed"); 513 key_free(k); 514 goto send; 515 } 516 break; 517 case 2: 518 k = key_private_deserialize(&e->request); 519 if (k == NULL) { 520 buffer_clear(&e->request); 521 goto send; 522 } 523 break; 524 } 525 comment = buffer_get_string(&e->request, NULL); 526 if (k == NULL) { 527 free(comment); 528 goto send; 529 } 530 while (buffer_len(&e->request)) { 531 switch ((type = buffer_get_char(&e->request))) { 532 case SSH_AGENT_CONSTRAIN_LIFETIME: 533 death = monotime() + buffer_get_int(&e->request); 534 break; 535 case SSH_AGENT_CONSTRAIN_CONFIRM: 536 confirm = 1; 537 break; 538 default: 539 error("process_add_identity: " 540 "Unknown constraint type %d", type); 541 free(comment); 542 key_free(k); 543 goto send; 544 } 545 } 546 success = 1; 547 if (lifetime && !death) 548 death = monotime() + lifetime; 549 if ((id = lookup_identity(k, version)) == NULL) { 550 id = xcalloc(1, sizeof(Identity)); 551 id->key = k; 552 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 553 /* Increment the number of identities. */ 554 tab->nentries++; 555 } else { 556 key_free(k); 557 free(id->comment); 558 } 559 id->comment = comment; 560 id->death = death; 561 id->confirm = confirm; 562 send: 563 buffer_put_int(&e->output, 1); 564 buffer_put_char(&e->output, 565 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 566 } 567 568 /* XXX todo: encrypt sensitive data with passphrase */ 569 static void 570 process_lock_agent(SocketEntry *e, int lock) 571 { 572 int success = 0; 573 char *passwd; 574 575 passwd = buffer_get_string(&e->request, NULL); 576 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 577 locked = 0; 578 explicit_bzero(lock_passwd, strlen(lock_passwd)); 579 free(lock_passwd); 580 lock_passwd = NULL; 581 success = 1; 582 } else if (!locked && lock) { 583 locked = 1; 584 lock_passwd = xstrdup(passwd); 585 success = 1; 586 } 587 explicit_bzero(passwd, strlen(passwd)); 588 free(passwd); 589 590 buffer_put_int(&e->output, 1); 591 buffer_put_char(&e->output, 592 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 593 } 594 595 static void 596 no_identities(SocketEntry *e, u_int type) 597 { 598 Buffer msg; 599 600 buffer_init(&msg); 601 buffer_put_char(&msg, 602 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 603 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 604 buffer_put_int(&msg, 0); 605 buffer_put_int(&e->output, buffer_len(&msg)); 606 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 607 buffer_free(&msg); 608 } 609 610 #ifdef ENABLE_PKCS11 611 static void 612 process_add_smartcard_key(SocketEntry *e) 613 { 614 char *provider = NULL, *pin; 615 int i, type, version, count = 0, success = 0, confirm = 0; 616 time_t death = 0; 617 Key **keys = NULL, *k; 618 Identity *id; 619 Idtab *tab; 620 621 provider = buffer_get_string(&e->request, NULL); 622 pin = buffer_get_string(&e->request, NULL); 623 624 while (buffer_len(&e->request)) { 625 switch ((type = buffer_get_char(&e->request))) { 626 case SSH_AGENT_CONSTRAIN_LIFETIME: 627 death = monotime() + buffer_get_int(&e->request); 628 break; 629 case SSH_AGENT_CONSTRAIN_CONFIRM: 630 confirm = 1; 631 break; 632 default: 633 error("process_add_smartcard_key: " 634 "Unknown constraint type %d", type); 635 goto send; 636 } 637 } 638 if (lifetime && !death) 639 death = monotime() + lifetime; 640 641 count = pkcs11_add_provider(provider, pin, &keys); 642 for (i = 0; i < count; i++) { 643 k = keys[i]; 644 version = k->type == KEY_RSA1 ? 1 : 2; 645 tab = idtab_lookup(version); 646 if (lookup_identity(k, version) == NULL) { 647 id = xcalloc(1, sizeof(Identity)); 648 id->key = k; 649 id->provider = xstrdup(provider); 650 id->comment = xstrdup(provider); /* XXX */ 651 id->death = death; 652 id->confirm = confirm; 653 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 654 tab->nentries++; 655 success = 1; 656 } else { 657 key_free(k); 658 } 659 keys[i] = NULL; 660 } 661 send: 662 free(pin); 663 free(provider); 664 free(keys); 665 buffer_put_int(&e->output, 1); 666 buffer_put_char(&e->output, 667 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 668 } 669 670 static void 671 process_remove_smartcard_key(SocketEntry *e) 672 { 673 char *provider = NULL, *pin = NULL; 674 int version, success = 0; 675 Identity *id, *nxt; 676 Idtab *tab; 677 678 provider = buffer_get_string(&e->request, NULL); 679 pin = buffer_get_string(&e->request, NULL); 680 free(pin); 681 682 for (version = 1; version < 3; version++) { 683 tab = idtab_lookup(version); 684 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 685 nxt = TAILQ_NEXT(id, next); 686 /* Skip file--based keys */ 687 if (id->provider == NULL) 688 continue; 689 if (!strcmp(provider, id->provider)) { 690 TAILQ_REMOVE(&tab->idlist, id, next); 691 free_identity(id); 692 tab->nentries--; 693 } 694 } 695 } 696 if (pkcs11_del_provider(provider) == 0) 697 success = 1; 698 else 699 error("process_remove_smartcard_key:" 700 " pkcs11_del_provider failed"); 701 free(provider); 702 buffer_put_int(&e->output, 1); 703 buffer_put_char(&e->output, 704 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 705 } 706 #endif /* ENABLE_PKCS11 */ 707 708 /* dispatch incoming messages */ 709 710 static void 711 process_message(SocketEntry *e) 712 { 713 u_int msg_len, type; 714 u_char *cp; 715 716 if (buffer_len(&e->input) < 5) 717 return; /* Incomplete message. */ 718 cp = buffer_ptr(&e->input); 719 msg_len = get_u32(cp); 720 if (msg_len > 256 * 1024) { 721 close_socket(e); 722 return; 723 } 724 if (buffer_len(&e->input) < msg_len + 4) 725 return; 726 727 /* move the current input to e->request */ 728 buffer_consume(&e->input, 4); 729 buffer_clear(&e->request); 730 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 731 buffer_consume(&e->input, msg_len); 732 type = buffer_get_char(&e->request); 733 734 /* check wheter agent is locked */ 735 if (locked && type != SSH_AGENTC_UNLOCK) { 736 buffer_clear(&e->request); 737 switch (type) { 738 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 739 case SSH2_AGENTC_REQUEST_IDENTITIES: 740 /* send empty lists */ 741 no_identities(e, type); 742 break; 743 default: 744 /* send a fail message for all other request types */ 745 buffer_put_int(&e->output, 1); 746 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 747 } 748 return; 749 } 750 751 debug("type %d", type); 752 switch (type) { 753 case SSH_AGENTC_LOCK: 754 case SSH_AGENTC_UNLOCK: 755 process_lock_agent(e, type == SSH_AGENTC_LOCK); 756 break; 757 /* ssh1 */ 758 case SSH_AGENTC_RSA_CHALLENGE: 759 process_authentication_challenge1(e); 760 break; 761 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 762 process_request_identities(e, 1); 763 break; 764 case SSH_AGENTC_ADD_RSA_IDENTITY: 765 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 766 process_add_identity(e, 1); 767 break; 768 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 769 process_remove_identity(e, 1); 770 break; 771 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 772 process_remove_all_identities(e, 1); 773 break; 774 /* ssh2 */ 775 case SSH2_AGENTC_SIGN_REQUEST: 776 process_sign_request2(e); 777 break; 778 case SSH2_AGENTC_REQUEST_IDENTITIES: 779 process_request_identities(e, 2); 780 break; 781 case SSH2_AGENTC_ADD_IDENTITY: 782 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 783 process_add_identity(e, 2); 784 break; 785 case SSH2_AGENTC_REMOVE_IDENTITY: 786 process_remove_identity(e, 2); 787 break; 788 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 789 process_remove_all_identities(e, 2); 790 break; 791 #ifdef ENABLE_PKCS11 792 case SSH_AGENTC_ADD_SMARTCARD_KEY: 793 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 794 process_add_smartcard_key(e); 795 break; 796 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 797 process_remove_smartcard_key(e); 798 break; 799 #endif /* ENABLE_PKCS11 */ 800 default: 801 /* Unknown message. Respond with failure. */ 802 error("Unknown message %d", type); 803 buffer_clear(&e->request); 804 buffer_put_int(&e->output, 1); 805 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 806 break; 807 } 808 } 809 810 static void 811 new_socket(sock_type type, int fd) 812 { 813 u_int i, old_alloc, new_alloc; 814 815 if (type == AUTH_CONNECTION) { 816 debug("xcount %d -> %d", xcount, xcount + 1); 817 ++xcount; 818 } 819 set_nonblock(fd); 820 821 if (fd > max_fd) 822 max_fd = fd; 823 824 for (i = 0; i < sockets_alloc; i++) 825 if (sockets[i].type == AUTH_UNUSED) { 826 sockets[i].fd = fd; 827 buffer_init(&sockets[i].input); 828 buffer_init(&sockets[i].output); 829 buffer_init(&sockets[i].request); 830 sockets[i].type = type; 831 return; 832 } 833 old_alloc = sockets_alloc; 834 new_alloc = sockets_alloc + 10; 835 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0])); 836 for (i = old_alloc; i < new_alloc; i++) 837 sockets[i].type = AUTH_UNUSED; 838 sockets_alloc = new_alloc; 839 sockets[old_alloc].fd = fd; 840 buffer_init(&sockets[old_alloc].input); 841 buffer_init(&sockets[old_alloc].output); 842 buffer_init(&sockets[old_alloc].request); 843 sockets[old_alloc].type = type; 844 } 845 846 static int 847 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 848 struct timeval **tvpp) 849 { 850 u_int i, sz; 851 int n = 0; 852 static struct timeval tv; 853 time_t deadline; 854 855 for (i = 0; i < sockets_alloc; i++) { 856 switch (sockets[i].type) { 857 case AUTH_SOCKET: 858 case AUTH_CONNECTION: 859 n = MAX(n, sockets[i].fd); 860 break; 861 case AUTH_UNUSED: 862 break; 863 default: 864 fatal("Unknown socket type %d", sockets[i].type); 865 break; 866 } 867 } 868 869 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 870 if (*fdrp == NULL || sz > *nallocp) { 871 free(*fdrp); 872 free(*fdwp); 873 *fdrp = xmalloc(sz); 874 *fdwp = xmalloc(sz); 875 *nallocp = sz; 876 } 877 if (n < *fdl) 878 debug("XXX shrink: %d < %d", n, *fdl); 879 *fdl = n; 880 memset(*fdrp, 0, sz); 881 memset(*fdwp, 0, sz); 882 883 for (i = 0; i < sockets_alloc; i++) { 884 switch (sockets[i].type) { 885 case AUTH_SOCKET: 886 case AUTH_CONNECTION: 887 FD_SET(sockets[i].fd, *fdrp); 888 if (buffer_len(&sockets[i].output) > 0) 889 FD_SET(sockets[i].fd, *fdwp); 890 break; 891 default: 892 break; 893 } 894 } 895 deadline = reaper(); 896 if (parent_alive_interval != 0) 897 deadline = (deadline == 0) ? parent_alive_interval : 898 MIN(deadline, parent_alive_interval); 899 if (deadline == 0) { 900 *tvpp = NULL; 901 } else { 902 tv.tv_sec = deadline; 903 tv.tv_usec = 0; 904 *tvpp = &tv; 905 } 906 return (1); 907 } 908 909 static void 910 after_select(fd_set *readset, fd_set *writeset) 911 { 912 struct sockaddr_un sunaddr; 913 socklen_t slen; 914 char buf[1024]; 915 int len, sock; 916 u_int i, orig_alloc; 917 uid_t euid; 918 gid_t egid; 919 920 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++) 921 switch (sockets[i].type) { 922 case AUTH_UNUSED: 923 break; 924 case AUTH_SOCKET: 925 if (FD_ISSET(sockets[i].fd, readset)) { 926 slen = sizeof(sunaddr); 927 sock = accept(sockets[i].fd, 928 (struct sockaddr *)&sunaddr, &slen); 929 if (sock < 0) { 930 error("accept from AUTH_SOCKET: %s", 931 strerror(errno)); 932 break; 933 } 934 if (getpeereid(sock, &euid, &egid) < 0) { 935 error("getpeereid %d failed: %s", 936 sock, strerror(errno)); 937 close(sock); 938 break; 939 } 940 if ((euid != 0) && (getuid() != euid)) { 941 error("uid mismatch: " 942 "peer euid %u != uid %u", 943 (u_int) euid, (u_int) getuid()); 944 close(sock); 945 break; 946 } 947 new_socket(AUTH_CONNECTION, sock); 948 } 949 break; 950 case AUTH_CONNECTION: 951 if (buffer_len(&sockets[i].output) > 0 && 952 FD_ISSET(sockets[i].fd, writeset)) { 953 len = write(sockets[i].fd, 954 buffer_ptr(&sockets[i].output), 955 buffer_len(&sockets[i].output)); 956 if (len == -1 && (errno == EAGAIN || 957 errno == EWOULDBLOCK || 958 errno == EINTR)) 959 continue; 960 if (len <= 0) { 961 close_socket(&sockets[i]); 962 break; 963 } 964 buffer_consume(&sockets[i].output, len); 965 } 966 if (FD_ISSET(sockets[i].fd, readset)) { 967 len = read(sockets[i].fd, buf, sizeof(buf)); 968 if (len == -1 && (errno == EAGAIN || 969 errno == EWOULDBLOCK || 970 errno == EINTR)) 971 continue; 972 if (len <= 0) { 973 close_socket(&sockets[i]); 974 break; 975 } 976 buffer_append(&sockets[i].input, buf, len); 977 process_message(&sockets[i]); 978 } 979 break; 980 default: 981 fatal("Unknown type %d", sockets[i].type); 982 } 983 } 984 985 static void 986 cleanup_socket(void) 987 { 988 if (socket_name[0]) 989 unlink(socket_name); 990 if (socket_dir[0]) 991 rmdir(socket_dir); 992 } 993 994 void 995 cleanup_exit(int i) 996 { 997 cleanup_socket(); 998 _exit(i); 999 } 1000 1001 /*ARGSUSED*/ 1002 static void 1003 cleanup_handler(int sig) 1004 { 1005 cleanup_socket(); 1006 #ifdef ENABLE_PKCS11 1007 pkcs11_terminate(); 1008 #endif 1009 _exit(2); 1010 } 1011 1012 static void 1013 check_parent_exists(void) 1014 { 1015 /* 1016 * If our parent has exited then getppid() will return (pid_t)1, 1017 * so testing for that should be safe. 1018 */ 1019 if (parent_pid != -1 && getppid() != parent_pid) { 1020 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1021 cleanup_socket(); 1022 _exit(2); 1023 } 1024 } 1025 1026 static void 1027 usage(void) 1028 { 1029 fprintf(stderr, "usage: %s [options] [command [arg ...]]\n", 1030 __progname); 1031 fprintf(stderr, "Options:\n"); 1032 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 1033 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 1034 fprintf(stderr, " -k Kill the current agent.\n"); 1035 fprintf(stderr, " -d Debug mode.\n"); 1036 fprintf(stderr, " -a socket Bind agent socket to given name.\n"); 1037 fprintf(stderr, " -t life Default identity lifetime (seconds).\n"); 1038 fprintf(stderr, " -x Exit when the last client disconnects.\n"); 1039 exit(1); 1040 } 1041 1042 int 1043 main(int ac, char **av) 1044 { 1045 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1046 int sock, fd, ch, result, saved_errno; 1047 u_int nalloc; 1048 char *shell, *format, *pidstr, *agentsocket = NULL; 1049 fd_set *readsetp = NULL, *writesetp = NULL; 1050 struct sockaddr_un sunaddr; 1051 #ifdef HAVE_SETRLIMIT 1052 struct rlimit rlim; 1053 #endif 1054 int prev_mask; 1055 extern int optind; 1056 extern char *optarg; 1057 pid_t pid; 1058 char pidstrbuf[1 + 3 * sizeof pid]; 1059 struct timeval *tvp = NULL; 1060 size_t len; 1061 1062 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1063 sanitise_stdfd(); 1064 1065 /* drop */ 1066 setegid(getgid()); 1067 setgid(getgid()); 1068 setuid(geteuid()); 1069 1070 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) 1071 /* Disable ptrace on Linux without sgid bit */ 1072 prctl(PR_SET_DUMPABLE, 0); 1073 #endif 1074 1075 OpenSSL_add_all_algorithms(); 1076 1077 __progname = ssh_get_progname(av[0]); 1078 seed_rng(); 1079 1080 while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) { 1081 switch (ch) { 1082 case 'c': 1083 if (s_flag) 1084 usage(); 1085 c_flag++; 1086 break; 1087 case 'k': 1088 k_flag++; 1089 break; 1090 case 's': 1091 if (c_flag) 1092 usage(); 1093 s_flag++; 1094 break; 1095 case 'd': 1096 if (d_flag) 1097 usage(); 1098 d_flag++; 1099 break; 1100 case 'a': 1101 agentsocket = optarg; 1102 break; 1103 case 't': 1104 if ((lifetime = convtime(optarg)) == -1) { 1105 fprintf(stderr, "Invalid lifetime\n"); 1106 usage(); 1107 } 1108 break; 1109 case 'x': 1110 xcount = 0; 1111 break; 1112 default: 1113 usage(); 1114 } 1115 } 1116 ac -= optind; 1117 av += optind; 1118 1119 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1120 usage(); 1121 1122 if (ac == 0 && !c_flag && !s_flag) { 1123 shell = getenv("SHELL"); 1124 if (shell != NULL && (len = strlen(shell)) > 2 && 1125 strncmp(shell + len - 3, "csh", 3) == 0) 1126 c_flag = 1; 1127 } 1128 if (k_flag) { 1129 const char *errstr = NULL; 1130 1131 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1132 if (pidstr == NULL) { 1133 fprintf(stderr, "%s not set, cannot kill agent\n", 1134 SSH_AGENTPID_ENV_NAME); 1135 exit(1); 1136 } 1137 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1138 if (errstr) { 1139 fprintf(stderr, 1140 "%s=\"%s\", which is not a good PID: %s\n", 1141 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1142 exit(1); 1143 } 1144 if (kill(pid, SIGTERM) == -1) { 1145 perror("kill"); 1146 exit(1); 1147 } 1148 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1149 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1150 printf(format, SSH_AGENTPID_ENV_NAME); 1151 printf("echo Agent pid %ld killed;\n", (long)pid); 1152 exit(0); 1153 } 1154 parent_pid = getpid(); 1155 1156 if (agentsocket == NULL) { 1157 /* Create private directory for agent socket */ 1158 mktemp_proto(socket_dir, sizeof(socket_dir)); 1159 if (mkdtemp(socket_dir) == NULL) { 1160 perror("mkdtemp: private socket dir"); 1161 exit(1); 1162 } 1163 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1164 (long)parent_pid); 1165 } else { 1166 /* Try to use specified agent socket */ 1167 socket_dir[0] = '\0'; 1168 strlcpy(socket_name, agentsocket, sizeof socket_name); 1169 } 1170 1171 /* 1172 * Create socket early so it will exist before command gets run from 1173 * the parent. 1174 */ 1175 sock = socket(AF_UNIX, SOCK_STREAM, 0); 1176 if (sock < 0) { 1177 perror("socket"); 1178 *socket_name = '\0'; /* Don't unlink any existing file */ 1179 cleanup_exit(1); 1180 } 1181 memset(&sunaddr, 0, sizeof(sunaddr)); 1182 sunaddr.sun_family = AF_UNIX; 1183 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 1184 prev_mask = umask(0177); 1185 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) { 1186 perror("bind"); 1187 *socket_name = '\0'; /* Don't unlink any existing file */ 1188 umask(prev_mask); 1189 cleanup_exit(1); 1190 } 1191 umask(prev_mask); 1192 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 1193 perror("listen"); 1194 cleanup_exit(1); 1195 } 1196 1197 /* 1198 * Fork, and have the parent execute the command, if any, or present 1199 * the socket data. The child continues as the authentication agent. 1200 */ 1201 if (d_flag) { 1202 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1203 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1204 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1205 SSH_AUTHSOCKET_ENV_NAME); 1206 printf("echo Agent pid %ld;\n", (long)parent_pid); 1207 goto skip; 1208 } 1209 pid = fork(); 1210 if (pid == -1) { 1211 perror("fork"); 1212 cleanup_exit(1); 1213 } 1214 if (pid != 0) { /* Parent - execute the given command. */ 1215 close(sock); 1216 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1217 if (ac == 0) { 1218 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1219 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1220 SSH_AUTHSOCKET_ENV_NAME); 1221 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1222 SSH_AGENTPID_ENV_NAME); 1223 printf("echo Agent pid %ld;\n", (long)pid); 1224 exit(0); 1225 } 1226 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1227 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1228 perror("setenv"); 1229 exit(1); 1230 } 1231 execvp(av[0], av); 1232 perror(av[0]); 1233 exit(1); 1234 } 1235 /* child */ 1236 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1237 1238 if (setsid() == -1) { 1239 error("setsid: %s", strerror(errno)); 1240 cleanup_exit(1); 1241 } 1242 1243 (void)chdir("/"); 1244 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1245 /* XXX might close listen socket */ 1246 (void)dup2(fd, STDIN_FILENO); 1247 (void)dup2(fd, STDOUT_FILENO); 1248 (void)dup2(fd, STDERR_FILENO); 1249 if (fd > 2) 1250 close(fd); 1251 } 1252 1253 #ifdef HAVE_SETRLIMIT 1254 /* deny core dumps, since memory contains unencrypted private keys */ 1255 rlim.rlim_cur = rlim.rlim_max = 0; 1256 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1257 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1258 cleanup_exit(1); 1259 } 1260 #endif 1261 1262 skip: 1263 1264 #ifdef ENABLE_PKCS11 1265 pkcs11_init(0); 1266 #endif 1267 new_socket(AUTH_SOCKET, sock); 1268 if (ac > 0) 1269 parent_alive_interval = 10; 1270 idtab_init(); 1271 signal(SIGPIPE, SIG_IGN); 1272 signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN); 1273 signal(SIGHUP, cleanup_handler); 1274 signal(SIGTERM, cleanup_handler); 1275 nalloc = 0; 1276 1277 while (1) { 1278 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp); 1279 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp); 1280 saved_errno = errno; 1281 if (parent_alive_interval != 0) 1282 check_parent_exists(); 1283 (void) reaper(); /* remove expired keys */ 1284 if (result < 0) { 1285 if (saved_errno == EINTR) 1286 continue; 1287 fatal("select: %s", strerror(saved_errno)); 1288 } else if (result > 0) 1289 after_select(readsetp, writesetp); 1290 } 1291 /* NOTREACHED */ 1292 } 1293