1 /* $OpenBSD: ssh-agent.c,v 1.190 2014/07/25 21:22:03 dtucker Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 __RCSID("$FreeBSD$"); 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 #ifdef WITH_OPENSSL 54 #include <openssl/evp.h> 55 #include "openbsd-compat/openssl-compat.h" 56 #endif 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #ifdef HAVE_PATHS_H 61 # include <paths.h> 62 #endif 63 #include <signal.h> 64 #include <stdarg.h> 65 #include <stdio.h> 66 #include <stdlib.h> 67 #include <time.h> 68 #include <string.h> 69 #include <unistd.h> 70 71 #include "xmalloc.h" 72 #include "ssh.h" 73 #include "rsa.h" 74 #include "buffer.h" 75 #include "key.h" 76 #include "authfd.h" 77 #include "compat.h" 78 #include "log.h" 79 #include "misc.h" 80 #include "digest.h" 81 82 #ifdef ENABLE_PKCS11 83 #include "ssh-pkcs11.h" 84 #endif 85 86 #if defined(HAVE_SYS_PRCTL_H) 87 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */ 88 #endif 89 90 typedef enum { 91 AUTH_UNUSED, 92 AUTH_SOCKET, 93 AUTH_CONNECTION 94 } sock_type; 95 96 typedef struct { 97 int fd; 98 sock_type type; 99 Buffer input; 100 Buffer output; 101 Buffer request; 102 } SocketEntry; 103 104 u_int sockets_alloc = 0; 105 SocketEntry *sockets = NULL; 106 107 typedef struct identity { 108 TAILQ_ENTRY(identity) next; 109 Key *key; 110 char *comment; 111 char *provider; 112 time_t death; 113 u_int confirm; 114 } Identity; 115 116 typedef struct { 117 int nentries; 118 TAILQ_HEAD(idqueue, identity) idlist; 119 } Idtab; 120 121 /* private key table, one per protocol version */ 122 Idtab idtable[3]; 123 124 int max_fd = 0; 125 126 /* pid of shell == parent of agent */ 127 pid_t parent_pid = -1; 128 time_t parent_alive_interval = 0; 129 130 /* pid of process for which cleanup_socket is applicable */ 131 pid_t cleanup_pid = 0; 132 133 /* pathname and directory for AUTH_SOCKET */ 134 char socket_name[MAXPATHLEN]; 135 char socket_dir[MAXPATHLEN]; 136 137 /* locking */ 138 int locked = 0; 139 char *lock_passwd = NULL; 140 141 extern char *__progname; 142 143 /* Default lifetime in seconds (0 == forever) */ 144 static long lifetime = 0; 145 146 /* 147 * Client connection count; incremented in new_socket() and decremented in 148 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 149 * normally initialized to 1, it will never reach 0. However, if the -x 150 * option is specified, it is initialized to 0 in main(); in that case, 151 * ssh-agent will exit as soon as it has had at least one client but no 152 * longer has any. 153 */ 154 static int xcount = 1; 155 156 static void 157 close_socket(SocketEntry *e) 158 { 159 int last = 0; 160 161 if (e->type == AUTH_CONNECTION) { 162 debug("xcount %d -> %d", xcount, xcount - 1); 163 if (--xcount == 0) 164 last = 1; 165 } 166 close(e->fd); 167 e->fd = -1; 168 e->type = AUTH_UNUSED; 169 buffer_free(&e->input); 170 buffer_free(&e->output); 171 buffer_free(&e->request); 172 if (last) 173 cleanup_exit(0); 174 } 175 176 static void 177 idtab_init(void) 178 { 179 int i; 180 181 for (i = 0; i <=2; i++) { 182 TAILQ_INIT(&idtable[i].idlist); 183 idtable[i].nentries = 0; 184 } 185 } 186 187 /* return private key table for requested protocol version */ 188 static Idtab * 189 idtab_lookup(int version) 190 { 191 if (version < 1 || version > 2) 192 fatal("internal error, bad protocol version %d", version); 193 return &idtable[version]; 194 } 195 196 static void 197 free_identity(Identity *id) 198 { 199 key_free(id->key); 200 free(id->provider); 201 free(id->comment); 202 free(id); 203 } 204 205 /* return matching private key for given public key */ 206 static Identity * 207 lookup_identity(Key *key, int version) 208 { 209 Identity *id; 210 211 Idtab *tab = idtab_lookup(version); 212 TAILQ_FOREACH(id, &tab->idlist, next) { 213 if (key_equal(key, id->key)) 214 return (id); 215 } 216 return (NULL); 217 } 218 219 /* Check confirmation of keysign request */ 220 static int 221 confirm_key(Identity *id) 222 { 223 char *p; 224 int ret = -1; 225 226 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 227 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.", 228 id->comment, p)) 229 ret = 0; 230 free(p); 231 232 return (ret); 233 } 234 235 /* send list of supported public keys to 'client' */ 236 static void 237 process_request_identities(SocketEntry *e, int version) 238 { 239 Idtab *tab = idtab_lookup(version); 240 Identity *id; 241 Buffer msg; 242 243 buffer_init(&msg); 244 buffer_put_char(&msg, (version == 1) ? 245 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 246 buffer_put_int(&msg, tab->nentries); 247 TAILQ_FOREACH(id, &tab->idlist, next) { 248 if (id->key->type == KEY_RSA1) { 249 #ifdef WITH_SSH1 250 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 251 buffer_put_bignum(&msg, id->key->rsa->e); 252 buffer_put_bignum(&msg, id->key->rsa->n); 253 #endif 254 } else { 255 u_char *blob; 256 u_int blen; 257 key_to_blob(id->key, &blob, &blen); 258 buffer_put_string(&msg, blob, blen); 259 free(blob); 260 } 261 buffer_put_cstring(&msg, id->comment); 262 } 263 buffer_put_int(&e->output, buffer_len(&msg)); 264 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 265 buffer_free(&msg); 266 } 267 268 #ifdef WITH_SSH1 269 /* ssh1 only */ 270 static void 271 process_authentication_challenge1(SocketEntry *e) 272 { 273 u_char buf[32], mdbuf[16], session_id[16]; 274 u_int response_type; 275 BIGNUM *challenge; 276 Identity *id; 277 int i, len; 278 Buffer msg; 279 struct ssh_digest_ctx *md; 280 Key *key; 281 282 buffer_init(&msg); 283 key = key_new(KEY_RSA1); 284 if ((challenge = BN_new()) == NULL) 285 fatal("process_authentication_challenge1: BN_new failed"); 286 287 (void) buffer_get_int(&e->request); /* ignored */ 288 buffer_get_bignum(&e->request, key->rsa->e); 289 buffer_get_bignum(&e->request, key->rsa->n); 290 buffer_get_bignum(&e->request, challenge); 291 292 /* Only protocol 1.1 is supported */ 293 if (buffer_len(&e->request) == 0) 294 goto failure; 295 buffer_get(&e->request, session_id, 16); 296 response_type = buffer_get_int(&e->request); 297 if (response_type != 1) 298 goto failure; 299 300 id = lookup_identity(key, 1); 301 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 302 Key *private = id->key; 303 /* Decrypt the challenge using the private key. */ 304 if (rsa_private_decrypt(challenge, challenge, private->rsa) != 0) 305 goto failure; 306 307 /* The response is MD5 of decrypted challenge plus session id. */ 308 len = BN_num_bytes(challenge); 309 if (len <= 0 || len > 32) { 310 logit("process_authentication_challenge: bad challenge length %d", len); 311 goto failure; 312 } 313 memset(buf, 0, 32); 314 BN_bn2bin(challenge, buf + 32 - len); 315 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 316 ssh_digest_update(md, buf, 32) < 0 || 317 ssh_digest_update(md, session_id, 16) < 0 || 318 ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0) 319 fatal("%s: md5 failed", __func__); 320 ssh_digest_free(md); 321 322 /* Send the response. */ 323 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 324 for (i = 0; i < 16; i++) 325 buffer_put_char(&msg, mdbuf[i]); 326 goto send; 327 } 328 329 failure: 330 /* Unknown identity or protocol error. Send failure. */ 331 buffer_put_char(&msg, SSH_AGENT_FAILURE); 332 send: 333 buffer_put_int(&e->output, buffer_len(&msg)); 334 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 335 key_free(key); 336 BN_clear_free(challenge); 337 buffer_free(&msg); 338 } 339 #endif 340 341 /* ssh2 only */ 342 static void 343 process_sign_request2(SocketEntry *e) 344 { 345 u_char *blob, *data, *signature = NULL; 346 u_int blen, dlen, slen = 0; 347 extern int datafellows; 348 int odatafellows; 349 int ok = -1, flags; 350 Buffer msg; 351 Key *key; 352 353 datafellows = 0; 354 355 blob = buffer_get_string(&e->request, &blen); 356 data = buffer_get_string(&e->request, &dlen); 357 358 flags = buffer_get_int(&e->request); 359 odatafellows = datafellows; 360 if (flags & SSH_AGENT_OLD_SIGNATURE) 361 datafellows = SSH_BUG_SIGBLOB; 362 363 key = key_from_blob(blob, blen); 364 if (key != NULL) { 365 Identity *id = lookup_identity(key, 2); 366 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 367 ok = key_sign(id->key, &signature, &slen, data, dlen); 368 key_free(key); 369 } 370 buffer_init(&msg); 371 if (ok == 0) { 372 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 373 buffer_put_string(&msg, signature, slen); 374 } else { 375 buffer_put_char(&msg, SSH_AGENT_FAILURE); 376 } 377 buffer_put_int(&e->output, buffer_len(&msg)); 378 buffer_append(&e->output, buffer_ptr(&msg), 379 buffer_len(&msg)); 380 buffer_free(&msg); 381 free(data); 382 free(blob); 383 free(signature); 384 datafellows = odatafellows; 385 } 386 387 /* shared */ 388 static void 389 process_remove_identity(SocketEntry *e, int version) 390 { 391 u_int blen; 392 int success = 0; 393 Key *key = NULL; 394 u_char *blob; 395 #ifdef WITH_SSH1 396 u_int bits; 397 #endif /* WITH_SSH1 */ 398 399 switch (version) { 400 #ifdef WITH_SSH1 401 case 1: 402 key = key_new(KEY_RSA1); 403 bits = buffer_get_int(&e->request); 404 buffer_get_bignum(&e->request, key->rsa->e); 405 buffer_get_bignum(&e->request, key->rsa->n); 406 407 if (bits != key_size(key)) 408 logit("Warning: identity keysize mismatch: actual %u, announced %u", 409 key_size(key), bits); 410 break; 411 #endif /* WITH_SSH1 */ 412 case 2: 413 blob = buffer_get_string(&e->request, &blen); 414 key = key_from_blob(blob, blen); 415 free(blob); 416 break; 417 } 418 if (key != NULL) { 419 Identity *id = lookup_identity(key, version); 420 if (id != NULL) { 421 /* 422 * We have this key. Free the old key. Since we 423 * don't want to leave empty slots in the middle of 424 * the array, we actually free the key there and move 425 * all the entries between the empty slot and the end 426 * of the array. 427 */ 428 Idtab *tab = idtab_lookup(version); 429 if (tab->nentries < 1) 430 fatal("process_remove_identity: " 431 "internal error: tab->nentries %d", 432 tab->nentries); 433 TAILQ_REMOVE(&tab->idlist, id, next); 434 free_identity(id); 435 tab->nentries--; 436 success = 1; 437 } 438 key_free(key); 439 } 440 buffer_put_int(&e->output, 1); 441 buffer_put_char(&e->output, 442 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 443 } 444 445 static void 446 process_remove_all_identities(SocketEntry *e, int version) 447 { 448 Idtab *tab = idtab_lookup(version); 449 Identity *id; 450 451 /* Loop over all identities and clear the keys. */ 452 for (id = TAILQ_FIRST(&tab->idlist); id; 453 id = TAILQ_FIRST(&tab->idlist)) { 454 TAILQ_REMOVE(&tab->idlist, id, next); 455 free_identity(id); 456 } 457 458 /* Mark that there are no identities. */ 459 tab->nentries = 0; 460 461 /* Send success. */ 462 buffer_put_int(&e->output, 1); 463 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 464 } 465 466 /* removes expired keys and returns number of seconds until the next expiry */ 467 static time_t 468 reaper(void) 469 { 470 time_t deadline = 0, now = monotime(); 471 Identity *id, *nxt; 472 int version; 473 Idtab *tab; 474 475 for (version = 1; version < 3; version++) { 476 tab = idtab_lookup(version); 477 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 478 nxt = TAILQ_NEXT(id, next); 479 if (id->death == 0) 480 continue; 481 if (now >= id->death) { 482 debug("expiring key '%s'", id->comment); 483 TAILQ_REMOVE(&tab->idlist, id, next); 484 free_identity(id); 485 tab->nentries--; 486 } else 487 deadline = (deadline == 0) ? id->death : 488 MIN(deadline, id->death); 489 } 490 } 491 if (deadline == 0 || deadline <= now) 492 return 0; 493 else 494 return (deadline - now); 495 } 496 497 static void 498 process_add_identity(SocketEntry *e, int version) 499 { 500 Idtab *tab = idtab_lookup(version); 501 Identity *id; 502 int type, success = 0, confirm = 0; 503 char *comment; 504 time_t death = 0; 505 Key *k = NULL; 506 507 switch (version) { 508 #ifdef WITH_SSH1 509 case 1: 510 k = key_new_private(KEY_RSA1); 511 (void) buffer_get_int(&e->request); /* ignored */ 512 buffer_get_bignum(&e->request, k->rsa->n); 513 buffer_get_bignum(&e->request, k->rsa->e); 514 buffer_get_bignum(&e->request, k->rsa->d); 515 buffer_get_bignum(&e->request, k->rsa->iqmp); 516 517 /* SSH and SSL have p and q swapped */ 518 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 519 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 520 521 /* Generate additional parameters */ 522 if (rsa_generate_additional_parameters(k->rsa) != 0) 523 fatal("%s: rsa_generate_additional_parameters " 524 "error", __func__); 525 526 /* enable blinding */ 527 if (RSA_blinding_on(k->rsa, NULL) != 1) { 528 error("process_add_identity: RSA_blinding_on failed"); 529 key_free(k); 530 goto send; 531 } 532 break; 533 #endif /* WITH_SSH1 */ 534 case 2: 535 k = key_private_deserialize(&e->request); 536 if (k == NULL) { 537 buffer_clear(&e->request); 538 goto send; 539 } 540 break; 541 } 542 if (k == NULL) 543 goto send; 544 comment = buffer_get_string(&e->request, NULL); 545 546 while (buffer_len(&e->request)) { 547 switch ((type = buffer_get_char(&e->request))) { 548 case SSH_AGENT_CONSTRAIN_LIFETIME: 549 death = monotime() + buffer_get_int(&e->request); 550 break; 551 case SSH_AGENT_CONSTRAIN_CONFIRM: 552 confirm = 1; 553 break; 554 default: 555 error("process_add_identity: " 556 "Unknown constraint type %d", type); 557 free(comment); 558 key_free(k); 559 goto send; 560 } 561 } 562 success = 1; 563 if (lifetime && !death) 564 death = monotime() + lifetime; 565 if ((id = lookup_identity(k, version)) == NULL) { 566 id = xcalloc(1, sizeof(Identity)); 567 id->key = k; 568 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 569 /* Increment the number of identities. */ 570 tab->nentries++; 571 } else { 572 key_free(k); 573 free(id->comment); 574 } 575 id->comment = comment; 576 id->death = death; 577 id->confirm = confirm; 578 send: 579 buffer_put_int(&e->output, 1); 580 buffer_put_char(&e->output, 581 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 582 } 583 584 /* XXX todo: encrypt sensitive data with passphrase */ 585 static void 586 process_lock_agent(SocketEntry *e, int lock) 587 { 588 int success = 0; 589 char *passwd; 590 591 passwd = buffer_get_string(&e->request, NULL); 592 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 593 locked = 0; 594 explicit_bzero(lock_passwd, strlen(lock_passwd)); 595 free(lock_passwd); 596 lock_passwd = NULL; 597 success = 1; 598 } else if (!locked && lock) { 599 locked = 1; 600 lock_passwd = xstrdup(passwd); 601 success = 1; 602 } 603 explicit_bzero(passwd, strlen(passwd)); 604 free(passwd); 605 606 buffer_put_int(&e->output, 1); 607 buffer_put_char(&e->output, 608 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 609 } 610 611 static void 612 no_identities(SocketEntry *e, u_int type) 613 { 614 Buffer msg; 615 616 buffer_init(&msg); 617 buffer_put_char(&msg, 618 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 619 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 620 buffer_put_int(&msg, 0); 621 buffer_put_int(&e->output, buffer_len(&msg)); 622 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 623 buffer_free(&msg); 624 } 625 626 #ifdef ENABLE_PKCS11 627 static void 628 process_add_smartcard_key(SocketEntry *e) 629 { 630 char *provider = NULL, *pin; 631 int i, type, version, count = 0, success = 0, confirm = 0; 632 time_t death = 0; 633 Key **keys = NULL, *k; 634 Identity *id; 635 Idtab *tab; 636 637 provider = buffer_get_string(&e->request, NULL); 638 pin = buffer_get_string(&e->request, NULL); 639 640 while (buffer_len(&e->request)) { 641 switch ((type = buffer_get_char(&e->request))) { 642 case SSH_AGENT_CONSTRAIN_LIFETIME: 643 death = monotime() + buffer_get_int(&e->request); 644 break; 645 case SSH_AGENT_CONSTRAIN_CONFIRM: 646 confirm = 1; 647 break; 648 default: 649 error("process_add_smartcard_key: " 650 "Unknown constraint type %d", type); 651 goto send; 652 } 653 } 654 if (lifetime && !death) 655 death = monotime() + lifetime; 656 657 count = pkcs11_add_provider(provider, pin, &keys); 658 for (i = 0; i < count; i++) { 659 k = keys[i]; 660 version = k->type == KEY_RSA1 ? 1 : 2; 661 tab = idtab_lookup(version); 662 if (lookup_identity(k, version) == NULL) { 663 id = xcalloc(1, sizeof(Identity)); 664 id->key = k; 665 id->provider = xstrdup(provider); 666 id->comment = xstrdup(provider); /* XXX */ 667 id->death = death; 668 id->confirm = confirm; 669 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 670 tab->nentries++; 671 success = 1; 672 } else { 673 key_free(k); 674 } 675 keys[i] = NULL; 676 } 677 send: 678 free(pin); 679 free(provider); 680 free(keys); 681 buffer_put_int(&e->output, 1); 682 buffer_put_char(&e->output, 683 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 684 } 685 686 static void 687 process_remove_smartcard_key(SocketEntry *e) 688 { 689 char *provider = NULL, *pin = NULL; 690 int version, success = 0; 691 Identity *id, *nxt; 692 Idtab *tab; 693 694 provider = buffer_get_string(&e->request, NULL); 695 pin = buffer_get_string(&e->request, NULL); 696 free(pin); 697 698 for (version = 1; version < 3; version++) { 699 tab = idtab_lookup(version); 700 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 701 nxt = TAILQ_NEXT(id, next); 702 /* Skip file--based keys */ 703 if (id->provider == NULL) 704 continue; 705 if (!strcmp(provider, id->provider)) { 706 TAILQ_REMOVE(&tab->idlist, id, next); 707 free_identity(id); 708 tab->nentries--; 709 } 710 } 711 } 712 if (pkcs11_del_provider(provider) == 0) 713 success = 1; 714 else 715 error("process_remove_smartcard_key:" 716 " pkcs11_del_provider failed"); 717 free(provider); 718 buffer_put_int(&e->output, 1); 719 buffer_put_char(&e->output, 720 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 721 } 722 #endif /* ENABLE_PKCS11 */ 723 724 /* dispatch incoming messages */ 725 726 static void 727 process_message(SocketEntry *e) 728 { 729 u_int msg_len, type; 730 u_char *cp; 731 732 if (buffer_len(&e->input) < 5) 733 return; /* Incomplete message. */ 734 cp = buffer_ptr(&e->input); 735 msg_len = get_u32(cp); 736 if (msg_len > 256 * 1024) { 737 close_socket(e); 738 return; 739 } 740 if (buffer_len(&e->input) < msg_len + 4) 741 return; 742 743 /* move the current input to e->request */ 744 buffer_consume(&e->input, 4); 745 buffer_clear(&e->request); 746 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 747 buffer_consume(&e->input, msg_len); 748 type = buffer_get_char(&e->request); 749 750 /* check wheter agent is locked */ 751 if (locked && type != SSH_AGENTC_UNLOCK) { 752 buffer_clear(&e->request); 753 switch (type) { 754 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 755 case SSH2_AGENTC_REQUEST_IDENTITIES: 756 /* send empty lists */ 757 no_identities(e, type); 758 break; 759 default: 760 /* send a fail message for all other request types */ 761 buffer_put_int(&e->output, 1); 762 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 763 } 764 return; 765 } 766 767 debug("type %d", type); 768 switch (type) { 769 case SSH_AGENTC_LOCK: 770 case SSH_AGENTC_UNLOCK: 771 process_lock_agent(e, type == SSH_AGENTC_LOCK); 772 break; 773 #ifdef WITH_SSH1 774 /* ssh1 */ 775 case SSH_AGENTC_RSA_CHALLENGE: 776 process_authentication_challenge1(e); 777 break; 778 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 779 process_request_identities(e, 1); 780 break; 781 case SSH_AGENTC_ADD_RSA_IDENTITY: 782 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 783 process_add_identity(e, 1); 784 break; 785 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 786 process_remove_identity(e, 1); 787 break; 788 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 789 process_remove_all_identities(e, 1); 790 break; 791 #endif 792 /* ssh2 */ 793 case SSH2_AGENTC_SIGN_REQUEST: 794 process_sign_request2(e); 795 break; 796 case SSH2_AGENTC_REQUEST_IDENTITIES: 797 process_request_identities(e, 2); 798 break; 799 case SSH2_AGENTC_ADD_IDENTITY: 800 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 801 process_add_identity(e, 2); 802 break; 803 case SSH2_AGENTC_REMOVE_IDENTITY: 804 process_remove_identity(e, 2); 805 break; 806 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 807 process_remove_all_identities(e, 2); 808 break; 809 #ifdef ENABLE_PKCS11 810 case SSH_AGENTC_ADD_SMARTCARD_KEY: 811 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 812 process_add_smartcard_key(e); 813 break; 814 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 815 process_remove_smartcard_key(e); 816 break; 817 #endif /* ENABLE_PKCS11 */ 818 default: 819 /* Unknown message. Respond with failure. */ 820 error("Unknown message %d", type); 821 buffer_clear(&e->request); 822 buffer_put_int(&e->output, 1); 823 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 824 break; 825 } 826 } 827 828 static void 829 new_socket(sock_type type, int fd) 830 { 831 u_int i, old_alloc, new_alloc; 832 833 if (type == AUTH_CONNECTION) { 834 debug("xcount %d -> %d", xcount, xcount + 1); 835 ++xcount; 836 } 837 set_nonblock(fd); 838 839 if (fd > max_fd) 840 max_fd = fd; 841 842 for (i = 0; i < sockets_alloc; i++) 843 if (sockets[i].type == AUTH_UNUSED) { 844 sockets[i].fd = fd; 845 buffer_init(&sockets[i].input); 846 buffer_init(&sockets[i].output); 847 buffer_init(&sockets[i].request); 848 sockets[i].type = type; 849 return; 850 } 851 old_alloc = sockets_alloc; 852 new_alloc = sockets_alloc + 10; 853 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0])); 854 for (i = old_alloc; i < new_alloc; i++) 855 sockets[i].type = AUTH_UNUSED; 856 sockets_alloc = new_alloc; 857 sockets[old_alloc].fd = fd; 858 buffer_init(&sockets[old_alloc].input); 859 buffer_init(&sockets[old_alloc].output); 860 buffer_init(&sockets[old_alloc].request); 861 sockets[old_alloc].type = type; 862 } 863 864 static int 865 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 866 struct timeval **tvpp) 867 { 868 u_int i, sz; 869 int n = 0; 870 static struct timeval tv; 871 time_t deadline; 872 873 for (i = 0; i < sockets_alloc; i++) { 874 switch (sockets[i].type) { 875 case AUTH_SOCKET: 876 case AUTH_CONNECTION: 877 n = MAX(n, sockets[i].fd); 878 break; 879 case AUTH_UNUSED: 880 break; 881 default: 882 fatal("Unknown socket type %d", sockets[i].type); 883 break; 884 } 885 } 886 887 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 888 if (*fdrp == NULL || sz > *nallocp) { 889 free(*fdrp); 890 free(*fdwp); 891 *fdrp = xmalloc(sz); 892 *fdwp = xmalloc(sz); 893 *nallocp = sz; 894 } 895 if (n < *fdl) 896 debug("XXX shrink: %d < %d", n, *fdl); 897 *fdl = n; 898 memset(*fdrp, 0, sz); 899 memset(*fdwp, 0, sz); 900 901 for (i = 0; i < sockets_alloc; i++) { 902 switch (sockets[i].type) { 903 case AUTH_SOCKET: 904 case AUTH_CONNECTION: 905 FD_SET(sockets[i].fd, *fdrp); 906 if (buffer_len(&sockets[i].output) > 0) 907 FD_SET(sockets[i].fd, *fdwp); 908 break; 909 default: 910 break; 911 } 912 } 913 deadline = reaper(); 914 if (parent_alive_interval != 0) 915 deadline = (deadline == 0) ? parent_alive_interval : 916 MIN(deadline, parent_alive_interval); 917 if (deadline == 0) { 918 *tvpp = NULL; 919 } else { 920 tv.tv_sec = deadline; 921 tv.tv_usec = 0; 922 *tvpp = &tv; 923 } 924 return (1); 925 } 926 927 static void 928 after_select(fd_set *readset, fd_set *writeset) 929 { 930 struct sockaddr_un sunaddr; 931 socklen_t slen; 932 char buf[1024]; 933 int len, sock; 934 u_int i, orig_alloc; 935 uid_t euid; 936 gid_t egid; 937 938 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++) 939 switch (sockets[i].type) { 940 case AUTH_UNUSED: 941 break; 942 case AUTH_SOCKET: 943 if (FD_ISSET(sockets[i].fd, readset)) { 944 slen = sizeof(sunaddr); 945 sock = accept(sockets[i].fd, 946 (struct sockaddr *)&sunaddr, &slen); 947 if (sock < 0) { 948 error("accept from AUTH_SOCKET: %s", 949 strerror(errno)); 950 break; 951 } 952 if (getpeereid(sock, &euid, &egid) < 0) { 953 error("getpeereid %d failed: %s", 954 sock, strerror(errno)); 955 close(sock); 956 break; 957 } 958 if ((euid != 0) && (getuid() != euid)) { 959 error("uid mismatch: " 960 "peer euid %u != uid %u", 961 (u_int) euid, (u_int) getuid()); 962 close(sock); 963 break; 964 } 965 new_socket(AUTH_CONNECTION, sock); 966 } 967 break; 968 case AUTH_CONNECTION: 969 if (buffer_len(&sockets[i].output) > 0 && 970 FD_ISSET(sockets[i].fd, writeset)) { 971 len = write(sockets[i].fd, 972 buffer_ptr(&sockets[i].output), 973 buffer_len(&sockets[i].output)); 974 if (len == -1 && (errno == EAGAIN || 975 errno == EWOULDBLOCK || 976 errno == EINTR)) 977 continue; 978 if (len <= 0) { 979 close_socket(&sockets[i]); 980 break; 981 } 982 buffer_consume(&sockets[i].output, len); 983 } 984 if (FD_ISSET(sockets[i].fd, readset)) { 985 len = read(sockets[i].fd, buf, sizeof(buf)); 986 if (len == -1 && (errno == EAGAIN || 987 errno == EWOULDBLOCK || 988 errno == EINTR)) 989 continue; 990 if (len <= 0) { 991 close_socket(&sockets[i]); 992 break; 993 } 994 buffer_append(&sockets[i].input, buf, len); 995 explicit_bzero(buf, sizeof(buf)); 996 process_message(&sockets[i]); 997 } 998 break; 999 default: 1000 fatal("Unknown type %d", sockets[i].type); 1001 } 1002 } 1003 1004 static void 1005 cleanup_socket(void) 1006 { 1007 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1008 return; 1009 debug("%s: cleanup", __func__); 1010 if (socket_name[0]) 1011 unlink(socket_name); 1012 if (socket_dir[0]) 1013 rmdir(socket_dir); 1014 } 1015 1016 void 1017 cleanup_exit(int i) 1018 { 1019 cleanup_socket(); 1020 _exit(i); 1021 } 1022 1023 /*ARGSUSED*/ 1024 static void 1025 cleanup_handler(int sig) 1026 { 1027 cleanup_socket(); 1028 #ifdef ENABLE_PKCS11 1029 pkcs11_terminate(); 1030 #endif 1031 _exit(2); 1032 } 1033 1034 static void 1035 check_parent_exists(void) 1036 { 1037 /* 1038 * If our parent has exited then getppid() will return (pid_t)1, 1039 * so testing for that should be safe. 1040 */ 1041 if (parent_pid != -1 && getppid() != parent_pid) { 1042 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1043 cleanup_socket(); 1044 _exit(2); 1045 } 1046 } 1047 1048 static void 1049 usage(void) 1050 { 1051 fprintf(stderr, 1052 "usage: ssh-agent [-c | -s] [-d] [-a bind_address] [-t life]\n" 1053 " [command [arg ...]]\n" 1054 " ssh-agent [-c | -s] -k\n"); 1055 fprintf(stderr, " -x Exit when the last client disconnects.\n"); 1056 exit(1); 1057 } 1058 1059 int 1060 main(int ac, char **av) 1061 { 1062 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1063 int sock, fd, ch, result, saved_errno; 1064 u_int nalloc; 1065 char *shell, *format, *pidstr, *agentsocket = NULL; 1066 fd_set *readsetp = NULL, *writesetp = NULL; 1067 #ifdef HAVE_SETRLIMIT 1068 struct rlimit rlim; 1069 #endif 1070 extern int optind; 1071 extern char *optarg; 1072 pid_t pid; 1073 char pidstrbuf[1 + 3 * sizeof pid]; 1074 struct timeval *tvp = NULL; 1075 size_t len; 1076 mode_t prev_mask; 1077 1078 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1079 sanitise_stdfd(); 1080 1081 /* drop */ 1082 setegid(getgid()); 1083 setgid(getgid()); 1084 setuid(geteuid()); 1085 1086 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) 1087 /* Disable ptrace on Linux without sgid bit */ 1088 prctl(PR_SET_DUMPABLE, 0); 1089 #endif 1090 1091 #ifdef WITH_OPENSSL 1092 OpenSSL_add_all_algorithms(); 1093 #endif 1094 1095 __progname = ssh_get_progname(av[0]); 1096 seed_rng(); 1097 1098 while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) { 1099 switch (ch) { 1100 case 'c': 1101 if (s_flag) 1102 usage(); 1103 c_flag++; 1104 break; 1105 case 'k': 1106 k_flag++; 1107 break; 1108 case 's': 1109 if (c_flag) 1110 usage(); 1111 s_flag++; 1112 break; 1113 case 'd': 1114 if (d_flag) 1115 usage(); 1116 d_flag++; 1117 break; 1118 case 'a': 1119 agentsocket = optarg; 1120 break; 1121 case 't': 1122 if ((lifetime = convtime(optarg)) == -1) { 1123 fprintf(stderr, "Invalid lifetime\n"); 1124 usage(); 1125 } 1126 break; 1127 case 'x': 1128 xcount = 0; 1129 break; 1130 default: 1131 usage(); 1132 } 1133 } 1134 ac -= optind; 1135 av += optind; 1136 1137 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1138 usage(); 1139 1140 if (ac == 0 && !c_flag && !s_flag) { 1141 shell = getenv("SHELL"); 1142 if (shell != NULL && (len = strlen(shell)) > 2 && 1143 strncmp(shell + len - 3, "csh", 3) == 0) 1144 c_flag = 1; 1145 } 1146 if (k_flag) { 1147 const char *errstr = NULL; 1148 1149 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1150 if (pidstr == NULL) { 1151 fprintf(stderr, "%s not set, cannot kill agent\n", 1152 SSH_AGENTPID_ENV_NAME); 1153 exit(1); 1154 } 1155 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1156 if (errstr) { 1157 fprintf(stderr, 1158 "%s=\"%s\", which is not a good PID: %s\n", 1159 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1160 exit(1); 1161 } 1162 if (kill(pid, SIGTERM) == -1) { 1163 perror("kill"); 1164 exit(1); 1165 } 1166 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1167 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1168 printf(format, SSH_AGENTPID_ENV_NAME); 1169 printf("echo Agent pid %ld killed;\n", (long)pid); 1170 exit(0); 1171 } 1172 parent_pid = getpid(); 1173 1174 if (agentsocket == NULL) { 1175 /* Create private directory for agent socket */ 1176 mktemp_proto(socket_dir, sizeof(socket_dir)); 1177 if (mkdtemp(socket_dir) == NULL) { 1178 perror("mkdtemp: private socket dir"); 1179 exit(1); 1180 } 1181 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1182 (long)parent_pid); 1183 } else { 1184 /* Try to use specified agent socket */ 1185 socket_dir[0] = '\0'; 1186 strlcpy(socket_name, agentsocket, sizeof socket_name); 1187 } 1188 1189 /* 1190 * Create socket early so it will exist before command gets run from 1191 * the parent. 1192 */ 1193 prev_mask = umask(0177); 1194 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1195 if (sock < 0) { 1196 /* XXX - unix_listener() calls error() not perror() */ 1197 *socket_name = '\0'; /* Don't unlink any existing file */ 1198 cleanup_exit(1); 1199 } 1200 umask(prev_mask); 1201 1202 /* 1203 * Fork, and have the parent execute the command, if any, or present 1204 * the socket data. The child continues as the authentication agent. 1205 */ 1206 if (d_flag) { 1207 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1208 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1209 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1210 SSH_AUTHSOCKET_ENV_NAME); 1211 printf("echo Agent pid %ld;\n", (long)parent_pid); 1212 goto skip; 1213 } 1214 pid = fork(); 1215 if (pid == -1) { 1216 perror("fork"); 1217 cleanup_exit(1); 1218 } 1219 if (pid != 0) { /* Parent - execute the given command. */ 1220 close(sock); 1221 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1222 if (ac == 0) { 1223 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1224 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1225 SSH_AUTHSOCKET_ENV_NAME); 1226 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1227 SSH_AGENTPID_ENV_NAME); 1228 printf("echo Agent pid %ld;\n", (long)pid); 1229 exit(0); 1230 } 1231 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1232 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1233 perror("setenv"); 1234 exit(1); 1235 } 1236 execvp(av[0], av); 1237 perror(av[0]); 1238 exit(1); 1239 } 1240 /* child */ 1241 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1242 1243 if (setsid() == -1) { 1244 error("setsid: %s", strerror(errno)); 1245 cleanup_exit(1); 1246 } 1247 1248 (void)chdir("/"); 1249 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1250 /* XXX might close listen socket */ 1251 (void)dup2(fd, STDIN_FILENO); 1252 (void)dup2(fd, STDOUT_FILENO); 1253 (void)dup2(fd, STDERR_FILENO); 1254 if (fd > 2) 1255 close(fd); 1256 } 1257 1258 #ifdef HAVE_SETRLIMIT 1259 /* deny core dumps, since memory contains unencrypted private keys */ 1260 rlim.rlim_cur = rlim.rlim_max = 0; 1261 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1262 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1263 cleanup_exit(1); 1264 } 1265 #endif 1266 1267 skip: 1268 1269 cleanup_pid = getpid(); 1270 1271 #ifdef ENABLE_PKCS11 1272 pkcs11_init(0); 1273 #endif 1274 new_socket(AUTH_SOCKET, sock); 1275 if (ac > 0) 1276 parent_alive_interval = 10; 1277 idtab_init(); 1278 signal(SIGPIPE, SIG_IGN); 1279 signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN); 1280 signal(SIGHUP, cleanup_handler); 1281 signal(SIGTERM, cleanup_handler); 1282 nalloc = 0; 1283 1284 while (1) { 1285 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp); 1286 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp); 1287 saved_errno = errno; 1288 if (parent_alive_interval != 0) 1289 check_parent_exists(); 1290 (void) reaper(); /* remove expired keys */ 1291 if (result < 0) { 1292 if (saved_errno == EINTR) 1293 continue; 1294 fatal("select: %s", strerror(saved_errno)); 1295 } else if (result > 0) 1296 after_select(readsetp, writesetp); 1297 } 1298 /* NOTREACHED */ 1299 } 1300