ssh-agent.c revision 264377
1/* $OpenBSD: ssh-agent.c,v 1.183 2014/02/02 03:44:31 djm Exp $ */ 2/* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37#include "includes.h" 38__RCSID("$FreeBSD: stable/10/crypto/openssh/ssh-agent.c 264377 2014-04-12 20:22:59Z des $"); 39 40#include <sys/types.h> 41#include <sys/param.h> 42#include <sys/resource.h> 43#include <sys/stat.h> 44#include <sys/socket.h> 45#ifdef HAVE_SYS_TIME_H 46# include <sys/time.h> 47#endif 48#ifdef HAVE_SYS_UN_H 49# include <sys/un.h> 50#endif 51#include "openbsd-compat/sys-queue.h" 52 53#include <openssl/evp.h> 54#include "openbsd-compat/openssl-compat.h" 55 56#include <errno.h> 57#include <fcntl.h> 58#ifdef HAVE_PATHS_H 59# include <paths.h> 60#endif 61#include <signal.h> 62#include <stdarg.h> 63#include <stdio.h> 64#include <stdlib.h> 65#include <time.h> 66#include <string.h> 67#include <unistd.h> 68 69#include "xmalloc.h" 70#include "ssh.h" 71#include "rsa.h" 72#include "buffer.h" 73#include "key.h" 74#include "authfd.h" 75#include "compat.h" 76#include "log.h" 77#include "misc.h" 78#include "digest.h" 79 80#ifdef ENABLE_PKCS11 81#include "ssh-pkcs11.h" 82#endif 83 84#if defined(HAVE_SYS_PRCTL_H) 85#include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */ 86#endif 87 88typedef enum { 89 AUTH_UNUSED, 90 AUTH_SOCKET, 91 AUTH_CONNECTION 92} sock_type; 93 94typedef struct { 95 int fd; 96 sock_type type; 97 Buffer input; 98 Buffer output; 99 Buffer request; 100} SocketEntry; 101 102u_int sockets_alloc = 0; 103SocketEntry *sockets = NULL; 104 105typedef struct identity { 106 TAILQ_ENTRY(identity) next; 107 Key *key; 108 char *comment; 109 char *provider; 110 time_t death; 111 u_int confirm; 112} Identity; 113 114typedef struct { 115 int nentries; 116 TAILQ_HEAD(idqueue, identity) idlist; 117} Idtab; 118 119/* private key table, one per protocol version */ 120Idtab idtable[3]; 121 122int max_fd = 0; 123 124/* pid of shell == parent of agent */ 125pid_t parent_pid = -1; 126time_t parent_alive_interval = 0; 127 128/* pathname and directory for AUTH_SOCKET */ 129char socket_name[MAXPATHLEN]; 130char socket_dir[MAXPATHLEN]; 131 132/* locking */ 133int locked = 0; 134char *lock_passwd = NULL; 135 136extern char *__progname; 137 138/* Default lifetime in seconds (0 == forever) */ 139static long lifetime = 0; 140 141/* 142 * Client connection count; incremented in new_socket() and decremented in 143 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 144 * normally initialized to 1, it will never reach 0. However, if the -x 145 * option is specified, it is initialized to 0 in main(); in that case, 146 * ssh-agent will exit as soon as it has had at least one client but no 147 * longer has any. 148 */ 149static int xcount = 1; 150 151static void 152close_socket(SocketEntry *e) 153{ 154 int last = 0; 155 156 if (e->type == AUTH_CONNECTION) { 157 debug("xcount %d -> %d", xcount, xcount - 1); 158 if (--xcount == 0) 159 last = 1; 160 } 161 close(e->fd); 162 e->fd = -1; 163 e->type = AUTH_UNUSED; 164 buffer_free(&e->input); 165 buffer_free(&e->output); 166 buffer_free(&e->request); 167 if (last) 168 cleanup_exit(0); 169} 170 171static void 172idtab_init(void) 173{ 174 int i; 175 176 for (i = 0; i <=2; i++) { 177 TAILQ_INIT(&idtable[i].idlist); 178 idtable[i].nentries = 0; 179 } 180} 181 182/* return private key table for requested protocol version */ 183static Idtab * 184idtab_lookup(int version) 185{ 186 if (version < 1 || version > 2) 187 fatal("internal error, bad protocol version %d", version); 188 return &idtable[version]; 189} 190 191static void 192free_identity(Identity *id) 193{ 194 key_free(id->key); 195 free(id->provider); 196 free(id->comment); 197 free(id); 198} 199 200/* return matching private key for given public key */ 201static Identity * 202lookup_identity(Key *key, int version) 203{ 204 Identity *id; 205 206 Idtab *tab = idtab_lookup(version); 207 TAILQ_FOREACH(id, &tab->idlist, next) { 208 if (key_equal(key, id->key)) 209 return (id); 210 } 211 return (NULL); 212} 213 214/* Check confirmation of keysign request */ 215static int 216confirm_key(Identity *id) 217{ 218 char *p; 219 int ret = -1; 220 221 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 222 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.", 223 id->comment, p)) 224 ret = 0; 225 free(p); 226 227 return (ret); 228} 229 230/* send list of supported public keys to 'client' */ 231static void 232process_request_identities(SocketEntry *e, int version) 233{ 234 Idtab *tab = idtab_lookup(version); 235 Identity *id; 236 Buffer msg; 237 238 buffer_init(&msg); 239 buffer_put_char(&msg, (version == 1) ? 240 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 241 buffer_put_int(&msg, tab->nentries); 242 TAILQ_FOREACH(id, &tab->idlist, next) { 243 if (id->key->type == KEY_RSA1) { 244 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 245 buffer_put_bignum(&msg, id->key->rsa->e); 246 buffer_put_bignum(&msg, id->key->rsa->n); 247 } else { 248 u_char *blob; 249 u_int blen; 250 key_to_blob(id->key, &blob, &blen); 251 buffer_put_string(&msg, blob, blen); 252 free(blob); 253 } 254 buffer_put_cstring(&msg, id->comment); 255 } 256 buffer_put_int(&e->output, buffer_len(&msg)); 257 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 258 buffer_free(&msg); 259} 260 261/* ssh1 only */ 262static void 263process_authentication_challenge1(SocketEntry *e) 264{ 265 u_char buf[32], mdbuf[16], session_id[16]; 266 u_int response_type; 267 BIGNUM *challenge; 268 Identity *id; 269 int i, len; 270 Buffer msg; 271 struct ssh_digest_ctx *md; 272 Key *key; 273 274 buffer_init(&msg); 275 key = key_new(KEY_RSA1); 276 if ((challenge = BN_new()) == NULL) 277 fatal("process_authentication_challenge1: BN_new failed"); 278 279 (void) buffer_get_int(&e->request); /* ignored */ 280 buffer_get_bignum(&e->request, key->rsa->e); 281 buffer_get_bignum(&e->request, key->rsa->n); 282 buffer_get_bignum(&e->request, challenge); 283 284 /* Only protocol 1.1 is supported */ 285 if (buffer_len(&e->request) == 0) 286 goto failure; 287 buffer_get(&e->request, session_id, 16); 288 response_type = buffer_get_int(&e->request); 289 if (response_type != 1) 290 goto failure; 291 292 id = lookup_identity(key, 1); 293 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 294 Key *private = id->key; 295 /* Decrypt the challenge using the private key. */ 296 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 297 goto failure; 298 299 /* The response is MD5 of decrypted challenge plus session id. */ 300 len = BN_num_bytes(challenge); 301 if (len <= 0 || len > 32) { 302 logit("process_authentication_challenge: bad challenge length %d", len); 303 goto failure; 304 } 305 memset(buf, 0, 32); 306 BN_bn2bin(challenge, buf + 32 - len); 307 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 308 ssh_digest_update(md, buf, 32) < 0 || 309 ssh_digest_update(md, session_id, 16) < 0 || 310 ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0) 311 fatal("%s: md5 failed", __func__); 312 ssh_digest_free(md); 313 314 /* Send the response. */ 315 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 316 for (i = 0; i < 16; i++) 317 buffer_put_char(&msg, mdbuf[i]); 318 goto send; 319 } 320 321failure: 322 /* Unknown identity or protocol error. Send failure. */ 323 buffer_put_char(&msg, SSH_AGENT_FAILURE); 324send: 325 buffer_put_int(&e->output, buffer_len(&msg)); 326 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 327 key_free(key); 328 BN_clear_free(challenge); 329 buffer_free(&msg); 330} 331 332/* ssh2 only */ 333static void 334process_sign_request2(SocketEntry *e) 335{ 336 u_char *blob, *data, *signature = NULL; 337 u_int blen, dlen, slen = 0; 338 extern int datafellows; 339 int odatafellows; 340 int ok = -1, flags; 341 Buffer msg; 342 Key *key; 343 344 datafellows = 0; 345 346 blob = buffer_get_string(&e->request, &blen); 347 data = buffer_get_string(&e->request, &dlen); 348 349 flags = buffer_get_int(&e->request); 350 odatafellows = datafellows; 351 if (flags & SSH_AGENT_OLD_SIGNATURE) 352 datafellows = SSH_BUG_SIGBLOB; 353 354 key = key_from_blob(blob, blen); 355 if (key != NULL) { 356 Identity *id = lookup_identity(key, 2); 357 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 358 ok = key_sign(id->key, &signature, &slen, data, dlen); 359 key_free(key); 360 } 361 buffer_init(&msg); 362 if (ok == 0) { 363 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 364 buffer_put_string(&msg, signature, slen); 365 } else { 366 buffer_put_char(&msg, SSH_AGENT_FAILURE); 367 } 368 buffer_put_int(&e->output, buffer_len(&msg)); 369 buffer_append(&e->output, buffer_ptr(&msg), 370 buffer_len(&msg)); 371 buffer_free(&msg); 372 free(data); 373 free(blob); 374 free(signature); 375 datafellows = odatafellows; 376} 377 378/* shared */ 379static void 380process_remove_identity(SocketEntry *e, int version) 381{ 382 u_int blen, bits; 383 int success = 0; 384 Key *key = NULL; 385 u_char *blob; 386 387 switch (version) { 388 case 1: 389 key = key_new(KEY_RSA1); 390 bits = buffer_get_int(&e->request); 391 buffer_get_bignum(&e->request, key->rsa->e); 392 buffer_get_bignum(&e->request, key->rsa->n); 393 394 if (bits != key_size(key)) 395 logit("Warning: identity keysize mismatch: actual %u, announced %u", 396 key_size(key), bits); 397 break; 398 case 2: 399 blob = buffer_get_string(&e->request, &blen); 400 key = key_from_blob(blob, blen); 401 free(blob); 402 break; 403 } 404 if (key != NULL) { 405 Identity *id = lookup_identity(key, version); 406 if (id != NULL) { 407 /* 408 * We have this key. Free the old key. Since we 409 * don't want to leave empty slots in the middle of 410 * the array, we actually free the key there and move 411 * all the entries between the empty slot and the end 412 * of the array. 413 */ 414 Idtab *tab = idtab_lookup(version); 415 if (tab->nentries < 1) 416 fatal("process_remove_identity: " 417 "internal error: tab->nentries %d", 418 tab->nentries); 419 TAILQ_REMOVE(&tab->idlist, id, next); 420 free_identity(id); 421 tab->nentries--; 422 success = 1; 423 } 424 key_free(key); 425 } 426 buffer_put_int(&e->output, 1); 427 buffer_put_char(&e->output, 428 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 429} 430 431static void 432process_remove_all_identities(SocketEntry *e, int version) 433{ 434 Idtab *tab = idtab_lookup(version); 435 Identity *id; 436 437 /* Loop over all identities and clear the keys. */ 438 for (id = TAILQ_FIRST(&tab->idlist); id; 439 id = TAILQ_FIRST(&tab->idlist)) { 440 TAILQ_REMOVE(&tab->idlist, id, next); 441 free_identity(id); 442 } 443 444 /* Mark that there are no identities. */ 445 tab->nentries = 0; 446 447 /* Send success. */ 448 buffer_put_int(&e->output, 1); 449 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 450} 451 452/* removes expired keys and returns number of seconds until the next expiry */ 453static time_t 454reaper(void) 455{ 456 time_t deadline = 0, now = monotime(); 457 Identity *id, *nxt; 458 int version; 459 Idtab *tab; 460 461 for (version = 1; version < 3; version++) { 462 tab = idtab_lookup(version); 463 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 464 nxt = TAILQ_NEXT(id, next); 465 if (id->death == 0) 466 continue; 467 if (now >= id->death) { 468 debug("expiring key '%s'", id->comment); 469 TAILQ_REMOVE(&tab->idlist, id, next); 470 free_identity(id); 471 tab->nentries--; 472 } else 473 deadline = (deadline == 0) ? id->death : 474 MIN(deadline, id->death); 475 } 476 } 477 if (deadline == 0 || deadline <= now) 478 return 0; 479 else 480 return (deadline - now); 481} 482 483static void 484process_add_identity(SocketEntry *e, int version) 485{ 486 Idtab *tab = idtab_lookup(version); 487 Identity *id; 488 int type, success = 0, confirm = 0; 489 char *comment; 490 time_t death = 0; 491 Key *k = NULL; 492 493 switch (version) { 494 case 1: 495 k = key_new_private(KEY_RSA1); 496 (void) buffer_get_int(&e->request); /* ignored */ 497 buffer_get_bignum(&e->request, k->rsa->n); 498 buffer_get_bignum(&e->request, k->rsa->e); 499 buffer_get_bignum(&e->request, k->rsa->d); 500 buffer_get_bignum(&e->request, k->rsa->iqmp); 501 502 /* SSH and SSL have p and q swapped */ 503 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 504 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 505 506 /* Generate additional parameters */ 507 rsa_generate_additional_parameters(k->rsa); 508 509 /* enable blinding */ 510 if (RSA_blinding_on(k->rsa, NULL) != 1) { 511 error("process_add_identity: RSA_blinding_on failed"); 512 key_free(k); 513 goto send; 514 } 515 break; 516 case 2: 517 k = key_private_deserialize(&e->request); 518 if (k == NULL) { 519 buffer_clear(&e->request); 520 goto send; 521 } 522 break; 523 } 524 comment = buffer_get_string(&e->request, NULL); 525 if (k == NULL) { 526 free(comment); 527 goto send; 528 } 529 while (buffer_len(&e->request)) { 530 switch ((type = buffer_get_char(&e->request))) { 531 case SSH_AGENT_CONSTRAIN_LIFETIME: 532 death = monotime() + buffer_get_int(&e->request); 533 break; 534 case SSH_AGENT_CONSTRAIN_CONFIRM: 535 confirm = 1; 536 break; 537 default: 538 error("process_add_identity: " 539 "Unknown constraint type %d", type); 540 free(comment); 541 key_free(k); 542 goto send; 543 } 544 } 545 success = 1; 546 if (lifetime && !death) 547 death = monotime() + lifetime; 548 if ((id = lookup_identity(k, version)) == NULL) { 549 id = xcalloc(1, sizeof(Identity)); 550 id->key = k; 551 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 552 /* Increment the number of identities. */ 553 tab->nentries++; 554 } else { 555 key_free(k); 556 free(id->comment); 557 } 558 id->comment = comment; 559 id->death = death; 560 id->confirm = confirm; 561send: 562 buffer_put_int(&e->output, 1); 563 buffer_put_char(&e->output, 564 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 565} 566 567/* XXX todo: encrypt sensitive data with passphrase */ 568static void 569process_lock_agent(SocketEntry *e, int lock) 570{ 571 int success = 0; 572 char *passwd; 573 574 passwd = buffer_get_string(&e->request, NULL); 575 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 576 locked = 0; 577 explicit_bzero(lock_passwd, strlen(lock_passwd)); 578 free(lock_passwd); 579 lock_passwd = NULL; 580 success = 1; 581 } else if (!locked && lock) { 582 locked = 1; 583 lock_passwd = xstrdup(passwd); 584 success = 1; 585 } 586 explicit_bzero(passwd, strlen(passwd)); 587 free(passwd); 588 589 buffer_put_int(&e->output, 1); 590 buffer_put_char(&e->output, 591 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 592} 593 594static void 595no_identities(SocketEntry *e, u_int type) 596{ 597 Buffer msg; 598 599 buffer_init(&msg); 600 buffer_put_char(&msg, 601 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 602 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 603 buffer_put_int(&msg, 0); 604 buffer_put_int(&e->output, buffer_len(&msg)); 605 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 606 buffer_free(&msg); 607} 608 609#ifdef ENABLE_PKCS11 610static void 611process_add_smartcard_key(SocketEntry *e) 612{ 613 char *provider = NULL, *pin; 614 int i, type, version, count = 0, success = 0, confirm = 0; 615 time_t death = 0; 616 Key **keys = NULL, *k; 617 Identity *id; 618 Idtab *tab; 619 620 provider = buffer_get_string(&e->request, NULL); 621 pin = buffer_get_string(&e->request, NULL); 622 623 while (buffer_len(&e->request)) { 624 switch ((type = buffer_get_char(&e->request))) { 625 case SSH_AGENT_CONSTRAIN_LIFETIME: 626 death = monotime() + buffer_get_int(&e->request); 627 break; 628 case SSH_AGENT_CONSTRAIN_CONFIRM: 629 confirm = 1; 630 break; 631 default: 632 error("process_add_smartcard_key: " 633 "Unknown constraint type %d", type); 634 goto send; 635 } 636 } 637 if (lifetime && !death) 638 death = monotime() + lifetime; 639 640 count = pkcs11_add_provider(provider, pin, &keys); 641 for (i = 0; i < count; i++) { 642 k = keys[i]; 643 version = k->type == KEY_RSA1 ? 1 : 2; 644 tab = idtab_lookup(version); 645 if (lookup_identity(k, version) == NULL) { 646 id = xcalloc(1, sizeof(Identity)); 647 id->key = k; 648 id->provider = xstrdup(provider); 649 id->comment = xstrdup(provider); /* XXX */ 650 id->death = death; 651 id->confirm = confirm; 652 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 653 tab->nentries++; 654 success = 1; 655 } else { 656 key_free(k); 657 } 658 keys[i] = NULL; 659 } 660send: 661 free(pin); 662 free(provider); 663 free(keys); 664 buffer_put_int(&e->output, 1); 665 buffer_put_char(&e->output, 666 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 667} 668 669static void 670process_remove_smartcard_key(SocketEntry *e) 671{ 672 char *provider = NULL, *pin = NULL; 673 int version, success = 0; 674 Identity *id, *nxt; 675 Idtab *tab; 676 677 provider = buffer_get_string(&e->request, NULL); 678 pin = buffer_get_string(&e->request, NULL); 679 free(pin); 680 681 for (version = 1; version < 3; version++) { 682 tab = idtab_lookup(version); 683 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 684 nxt = TAILQ_NEXT(id, next); 685 /* Skip file--based keys */ 686 if (id->provider == NULL) 687 continue; 688 if (!strcmp(provider, id->provider)) { 689 TAILQ_REMOVE(&tab->idlist, id, next); 690 free_identity(id); 691 tab->nentries--; 692 } 693 } 694 } 695 if (pkcs11_del_provider(provider) == 0) 696 success = 1; 697 else 698 error("process_remove_smartcard_key:" 699 " pkcs11_del_provider failed"); 700 free(provider); 701 buffer_put_int(&e->output, 1); 702 buffer_put_char(&e->output, 703 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 704} 705#endif /* ENABLE_PKCS11 */ 706 707/* dispatch incoming messages */ 708 709static void 710process_message(SocketEntry *e) 711{ 712 u_int msg_len, type; 713 u_char *cp; 714 715 if (buffer_len(&e->input) < 5) 716 return; /* Incomplete message. */ 717 cp = buffer_ptr(&e->input); 718 msg_len = get_u32(cp); 719 if (msg_len > 256 * 1024) { 720 close_socket(e); 721 return; 722 } 723 if (buffer_len(&e->input) < msg_len + 4) 724 return; 725 726 /* move the current input to e->request */ 727 buffer_consume(&e->input, 4); 728 buffer_clear(&e->request); 729 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 730 buffer_consume(&e->input, msg_len); 731 type = buffer_get_char(&e->request); 732 733 /* check wheter agent is locked */ 734 if (locked && type != SSH_AGENTC_UNLOCK) { 735 buffer_clear(&e->request); 736 switch (type) { 737 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 738 case SSH2_AGENTC_REQUEST_IDENTITIES: 739 /* send empty lists */ 740 no_identities(e, type); 741 break; 742 default: 743 /* send a fail message for all other request types */ 744 buffer_put_int(&e->output, 1); 745 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 746 } 747 return; 748 } 749 750 debug("type %d", type); 751 switch (type) { 752 case SSH_AGENTC_LOCK: 753 case SSH_AGENTC_UNLOCK: 754 process_lock_agent(e, type == SSH_AGENTC_LOCK); 755 break; 756 /* ssh1 */ 757 case SSH_AGENTC_RSA_CHALLENGE: 758 process_authentication_challenge1(e); 759 break; 760 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 761 process_request_identities(e, 1); 762 break; 763 case SSH_AGENTC_ADD_RSA_IDENTITY: 764 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 765 process_add_identity(e, 1); 766 break; 767 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 768 process_remove_identity(e, 1); 769 break; 770 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 771 process_remove_all_identities(e, 1); 772 break; 773 /* ssh2 */ 774 case SSH2_AGENTC_SIGN_REQUEST: 775 process_sign_request2(e); 776 break; 777 case SSH2_AGENTC_REQUEST_IDENTITIES: 778 process_request_identities(e, 2); 779 break; 780 case SSH2_AGENTC_ADD_IDENTITY: 781 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 782 process_add_identity(e, 2); 783 break; 784 case SSH2_AGENTC_REMOVE_IDENTITY: 785 process_remove_identity(e, 2); 786 break; 787 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 788 process_remove_all_identities(e, 2); 789 break; 790#ifdef ENABLE_PKCS11 791 case SSH_AGENTC_ADD_SMARTCARD_KEY: 792 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 793 process_add_smartcard_key(e); 794 break; 795 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 796 process_remove_smartcard_key(e); 797 break; 798#endif /* ENABLE_PKCS11 */ 799 default: 800 /* Unknown message. Respond with failure. */ 801 error("Unknown message %d", type); 802 buffer_clear(&e->request); 803 buffer_put_int(&e->output, 1); 804 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 805 break; 806 } 807} 808 809static void 810new_socket(sock_type type, int fd) 811{ 812 u_int i, old_alloc, new_alloc; 813 814 if (type == AUTH_CONNECTION) { 815 debug("xcount %d -> %d", xcount, xcount + 1); 816 ++xcount; 817 } 818 set_nonblock(fd); 819 820 if (fd > max_fd) 821 max_fd = fd; 822 823 for (i = 0; i < sockets_alloc; i++) 824 if (sockets[i].type == AUTH_UNUSED) { 825 sockets[i].fd = fd; 826 buffer_init(&sockets[i].input); 827 buffer_init(&sockets[i].output); 828 buffer_init(&sockets[i].request); 829 sockets[i].type = type; 830 return; 831 } 832 old_alloc = sockets_alloc; 833 new_alloc = sockets_alloc + 10; 834 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0])); 835 for (i = old_alloc; i < new_alloc; i++) 836 sockets[i].type = AUTH_UNUSED; 837 sockets_alloc = new_alloc; 838 sockets[old_alloc].fd = fd; 839 buffer_init(&sockets[old_alloc].input); 840 buffer_init(&sockets[old_alloc].output); 841 buffer_init(&sockets[old_alloc].request); 842 sockets[old_alloc].type = type; 843} 844 845static int 846prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 847 struct timeval **tvpp) 848{ 849 u_int i, sz; 850 int n = 0; 851 static struct timeval tv; 852 time_t deadline; 853 854 for (i = 0; i < sockets_alloc; i++) { 855 switch (sockets[i].type) { 856 case AUTH_SOCKET: 857 case AUTH_CONNECTION: 858 n = MAX(n, sockets[i].fd); 859 break; 860 case AUTH_UNUSED: 861 break; 862 default: 863 fatal("Unknown socket type %d", sockets[i].type); 864 break; 865 } 866 } 867 868 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 869 if (*fdrp == NULL || sz > *nallocp) { 870 free(*fdrp); 871 free(*fdwp); 872 *fdrp = xmalloc(sz); 873 *fdwp = xmalloc(sz); 874 *nallocp = sz; 875 } 876 if (n < *fdl) 877 debug("XXX shrink: %d < %d", n, *fdl); 878 *fdl = n; 879 memset(*fdrp, 0, sz); 880 memset(*fdwp, 0, sz); 881 882 for (i = 0; i < sockets_alloc; i++) { 883 switch (sockets[i].type) { 884 case AUTH_SOCKET: 885 case AUTH_CONNECTION: 886 FD_SET(sockets[i].fd, *fdrp); 887 if (buffer_len(&sockets[i].output) > 0) 888 FD_SET(sockets[i].fd, *fdwp); 889 break; 890 default: 891 break; 892 } 893 } 894 deadline = reaper(); 895 if (parent_alive_interval != 0) 896 deadline = (deadline == 0) ? parent_alive_interval : 897 MIN(deadline, parent_alive_interval); 898 if (deadline == 0) { 899 *tvpp = NULL; 900 } else { 901 tv.tv_sec = deadline; 902 tv.tv_usec = 0; 903 *tvpp = &tv; 904 } 905 return (1); 906} 907 908static void 909after_select(fd_set *readset, fd_set *writeset) 910{ 911 struct sockaddr_un sunaddr; 912 socklen_t slen; 913 char buf[1024]; 914 int len, sock; 915 u_int i, orig_alloc; 916 uid_t euid; 917 gid_t egid; 918 919 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++) 920 switch (sockets[i].type) { 921 case AUTH_UNUSED: 922 break; 923 case AUTH_SOCKET: 924 if (FD_ISSET(sockets[i].fd, readset)) { 925 slen = sizeof(sunaddr); 926 sock = accept(sockets[i].fd, 927 (struct sockaddr *)&sunaddr, &slen); 928 if (sock < 0) { 929 error("accept from AUTH_SOCKET: %s", 930 strerror(errno)); 931 break; 932 } 933 if (getpeereid(sock, &euid, &egid) < 0) { 934 error("getpeereid %d failed: %s", 935 sock, strerror(errno)); 936 close(sock); 937 break; 938 } 939 if ((euid != 0) && (getuid() != euid)) { 940 error("uid mismatch: " 941 "peer euid %u != uid %u", 942 (u_int) euid, (u_int) getuid()); 943 close(sock); 944 break; 945 } 946 new_socket(AUTH_CONNECTION, sock); 947 } 948 break; 949 case AUTH_CONNECTION: 950 if (buffer_len(&sockets[i].output) > 0 && 951 FD_ISSET(sockets[i].fd, writeset)) { 952 len = write(sockets[i].fd, 953 buffer_ptr(&sockets[i].output), 954 buffer_len(&sockets[i].output)); 955 if (len == -1 && (errno == EAGAIN || 956 errno == EWOULDBLOCK || 957 errno == EINTR)) 958 continue; 959 if (len <= 0) { 960 close_socket(&sockets[i]); 961 break; 962 } 963 buffer_consume(&sockets[i].output, len); 964 } 965 if (FD_ISSET(sockets[i].fd, readset)) { 966 len = read(sockets[i].fd, buf, sizeof(buf)); 967 if (len == -1 && (errno == EAGAIN || 968 errno == EWOULDBLOCK || 969 errno == EINTR)) 970 continue; 971 if (len <= 0) { 972 close_socket(&sockets[i]); 973 break; 974 } 975 buffer_append(&sockets[i].input, buf, len); 976 process_message(&sockets[i]); 977 } 978 break; 979 default: 980 fatal("Unknown type %d", sockets[i].type); 981 } 982} 983 984static void 985cleanup_socket(void) 986{ 987 if (socket_name[0]) 988 unlink(socket_name); 989 if (socket_dir[0]) 990 rmdir(socket_dir); 991} 992 993void 994cleanup_exit(int i) 995{ 996 cleanup_socket(); 997 _exit(i); 998} 999 1000/*ARGSUSED*/ 1001static void 1002cleanup_handler(int sig) 1003{ 1004 cleanup_socket(); 1005#ifdef ENABLE_PKCS11 1006 pkcs11_terminate(); 1007#endif 1008 _exit(2); 1009} 1010 1011static void 1012check_parent_exists(void) 1013{ 1014 /* 1015 * If our parent has exited then getppid() will return (pid_t)1, 1016 * so testing for that should be safe. 1017 */ 1018 if (parent_pid != -1 && getppid() != parent_pid) { 1019 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1020 cleanup_socket(); 1021 _exit(2); 1022 } 1023} 1024 1025static void 1026usage(void) 1027{ 1028 fprintf(stderr, "usage: %s [options] [command [arg ...]]\n", 1029 __progname); 1030 fprintf(stderr, "Options:\n"); 1031 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 1032 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 1033 fprintf(stderr, " -k Kill the current agent.\n"); 1034 fprintf(stderr, " -d Debug mode.\n"); 1035 fprintf(stderr, " -a socket Bind agent socket to given name.\n"); 1036 fprintf(stderr, " -t life Default identity lifetime (seconds).\n"); 1037 fprintf(stderr, " -x Exit when the last client disconnects.\n"); 1038 exit(1); 1039} 1040 1041int 1042main(int ac, char **av) 1043{ 1044 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1045 int sock, fd, ch, result, saved_errno; 1046 u_int nalloc; 1047 char *shell, *format, *pidstr, *agentsocket = NULL; 1048 fd_set *readsetp = NULL, *writesetp = NULL; 1049 struct sockaddr_un sunaddr; 1050#ifdef HAVE_SETRLIMIT 1051 struct rlimit rlim; 1052#endif 1053 int prev_mask; 1054 extern int optind; 1055 extern char *optarg; 1056 pid_t pid; 1057 char pidstrbuf[1 + 3 * sizeof pid]; 1058 struct timeval *tvp = NULL; 1059 size_t len; 1060 1061 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1062 sanitise_stdfd(); 1063 1064 /* drop */ 1065 setegid(getgid()); 1066 setgid(getgid()); 1067 setuid(geteuid()); 1068 1069#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) 1070 /* Disable ptrace on Linux without sgid bit */ 1071 prctl(PR_SET_DUMPABLE, 0); 1072#endif 1073 1074 OpenSSL_add_all_algorithms(); 1075 1076 __progname = ssh_get_progname(av[0]); 1077 seed_rng(); 1078 1079 while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) { 1080 switch (ch) { 1081 case 'c': 1082 if (s_flag) 1083 usage(); 1084 c_flag++; 1085 break; 1086 case 'k': 1087 k_flag++; 1088 break; 1089 case 's': 1090 if (c_flag) 1091 usage(); 1092 s_flag++; 1093 break; 1094 case 'd': 1095 if (d_flag) 1096 usage(); 1097 d_flag++; 1098 break; 1099 case 'a': 1100 agentsocket = optarg; 1101 break; 1102 case 't': 1103 if ((lifetime = convtime(optarg)) == -1) { 1104 fprintf(stderr, "Invalid lifetime\n"); 1105 usage(); 1106 } 1107 break; 1108 case 'x': 1109 xcount = 0; 1110 break; 1111 default: 1112 usage(); 1113 } 1114 } 1115 ac -= optind; 1116 av += optind; 1117 1118 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1119 usage(); 1120 1121 if (ac == 0 && !c_flag && !s_flag) { 1122 shell = getenv("SHELL"); 1123 if (shell != NULL && (len = strlen(shell)) > 2 && 1124 strncmp(shell + len - 3, "csh", 3) == 0) 1125 c_flag = 1; 1126 } 1127 if (k_flag) { 1128 const char *errstr = NULL; 1129 1130 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1131 if (pidstr == NULL) { 1132 fprintf(stderr, "%s not set, cannot kill agent\n", 1133 SSH_AGENTPID_ENV_NAME); 1134 exit(1); 1135 } 1136 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1137 if (errstr) { 1138 fprintf(stderr, 1139 "%s=\"%s\", which is not a good PID: %s\n", 1140 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1141 exit(1); 1142 } 1143 if (kill(pid, SIGTERM) == -1) { 1144 perror("kill"); 1145 exit(1); 1146 } 1147 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1148 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1149 printf(format, SSH_AGENTPID_ENV_NAME); 1150 printf("echo Agent pid %ld killed;\n", (long)pid); 1151 exit(0); 1152 } 1153 parent_pid = getpid(); 1154 1155 if (agentsocket == NULL) { 1156 /* Create private directory for agent socket */ 1157 mktemp_proto(socket_dir, sizeof(socket_dir)); 1158 if (mkdtemp(socket_dir) == NULL) { 1159 perror("mkdtemp: private socket dir"); 1160 exit(1); 1161 } 1162 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1163 (long)parent_pid); 1164 } else { 1165 /* Try to use specified agent socket */ 1166 socket_dir[0] = '\0'; 1167 strlcpy(socket_name, agentsocket, sizeof socket_name); 1168 } 1169 1170 /* 1171 * Create socket early so it will exist before command gets run from 1172 * the parent. 1173 */ 1174 sock = socket(AF_UNIX, SOCK_STREAM, 0); 1175 if (sock < 0) { 1176 perror("socket"); 1177 *socket_name = '\0'; /* Don't unlink any existing file */ 1178 cleanup_exit(1); 1179 } 1180 memset(&sunaddr, 0, sizeof(sunaddr)); 1181 sunaddr.sun_family = AF_UNIX; 1182 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 1183 prev_mask = umask(0177); 1184 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) { 1185 perror("bind"); 1186 *socket_name = '\0'; /* Don't unlink any existing file */ 1187 umask(prev_mask); 1188 cleanup_exit(1); 1189 } 1190 umask(prev_mask); 1191 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 1192 perror("listen"); 1193 cleanup_exit(1); 1194 } 1195 1196 /* 1197 * Fork, and have the parent execute the command, if any, or present 1198 * the socket data. The child continues as the authentication agent. 1199 */ 1200 if (d_flag) { 1201 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1202 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1203 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1204 SSH_AUTHSOCKET_ENV_NAME); 1205 printf("echo Agent pid %ld;\n", (long)parent_pid); 1206 goto skip; 1207 } 1208 pid = fork(); 1209 if (pid == -1) { 1210 perror("fork"); 1211 cleanup_exit(1); 1212 } 1213 if (pid != 0) { /* Parent - execute the given command. */ 1214 close(sock); 1215 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1216 if (ac == 0) { 1217 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1218 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1219 SSH_AUTHSOCKET_ENV_NAME); 1220 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1221 SSH_AGENTPID_ENV_NAME); 1222 printf("echo Agent pid %ld;\n", (long)pid); 1223 exit(0); 1224 } 1225 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1226 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1227 perror("setenv"); 1228 exit(1); 1229 } 1230 execvp(av[0], av); 1231 perror(av[0]); 1232 exit(1); 1233 } 1234 /* child */ 1235 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1236 1237 if (setsid() == -1) { 1238 error("setsid: %s", strerror(errno)); 1239 cleanup_exit(1); 1240 } 1241 1242 (void)chdir("/"); 1243 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1244 /* XXX might close listen socket */ 1245 (void)dup2(fd, STDIN_FILENO); 1246 (void)dup2(fd, STDOUT_FILENO); 1247 (void)dup2(fd, STDERR_FILENO); 1248 if (fd > 2) 1249 close(fd); 1250 } 1251 1252#ifdef HAVE_SETRLIMIT 1253 /* deny core dumps, since memory contains unencrypted private keys */ 1254 rlim.rlim_cur = rlim.rlim_max = 0; 1255 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1256 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1257 cleanup_exit(1); 1258 } 1259#endif 1260 1261skip: 1262 1263#ifdef ENABLE_PKCS11 1264 pkcs11_init(0); 1265#endif 1266 new_socket(AUTH_SOCKET, sock); 1267 if (ac > 0) 1268 parent_alive_interval = 10; 1269 idtab_init(); 1270 signal(SIGPIPE, SIG_IGN); 1271 signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN); 1272 signal(SIGHUP, cleanup_handler); 1273 signal(SIGTERM, cleanup_handler); 1274 nalloc = 0; 1275 1276 while (1) { 1277 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp); 1278 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp); 1279 saved_errno = errno; 1280 if (parent_alive_interval != 0) 1281 check_parent_exists(); 1282 (void) reaper(); /* remove expired keys */ 1283 if (result < 0) { 1284 if (saved_errno == EINTR) 1285 continue; 1286 fatal("select: %s", strerror(saved_errno)); 1287 } else if (result > 0) 1288 after_select(readsetp, writesetp); 1289 } 1290 /* NOTREACHED */ 1291} 1292