1 /* $OpenBSD: ssh-agent.c,v 1.159 2008/06/28 14:05:15 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("$FreeBSD$"); 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 <openssl/md5.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 80 #ifdef SMARTCARD 81 #include "scard.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 88 typedef enum { 89 AUTH_UNUSED, 90 AUTH_SOCKET, 91 AUTH_CONNECTION 92 } sock_type; 93 94 typedef struct { 95 int fd; 96 sock_type type; 97 Buffer input; 98 Buffer output; 99 Buffer request; 100 } SocketEntry; 101 102 u_int sockets_alloc = 0; 103 SocketEntry *sockets = NULL; 104 105 typedef struct identity { 106 TAILQ_ENTRY(identity) next; 107 Key *key; 108 char *comment; 109 u_int death; 110 u_int confirm; 111 } Identity; 112 113 typedef struct { 114 int nentries; 115 TAILQ_HEAD(idqueue, identity) idlist; 116 } Idtab; 117 118 /* private key table, one per protocol version */ 119 Idtab idtable[3]; 120 121 int max_fd = 0; 122 123 /* pid of shell == parent of agent */ 124 pid_t parent_pid = -1; 125 u_int parent_alive_interval = 0; 126 127 /* pathname and directory for AUTH_SOCKET */ 128 char socket_name[MAXPATHLEN]; 129 char socket_dir[MAXPATHLEN]; 130 131 /* locking */ 132 int locked = 0; 133 char *lock_passwd = NULL; 134 135 extern char *__progname; 136 137 /* Default lifetime (0 == forever) */ 138 static int lifetime = 0; 139 140 static void 141 close_socket(SocketEntry *e) 142 { 143 close(e->fd); 144 e->fd = -1; 145 e->type = AUTH_UNUSED; 146 buffer_free(&e->input); 147 buffer_free(&e->output); 148 buffer_free(&e->request); 149 } 150 151 static void 152 idtab_init(void) 153 { 154 int i; 155 156 for (i = 0; i <=2; i++) { 157 TAILQ_INIT(&idtable[i].idlist); 158 idtable[i].nentries = 0; 159 } 160 } 161 162 /* return private key table for requested protocol version */ 163 static Idtab * 164 idtab_lookup(int version) 165 { 166 if (version < 1 || version > 2) 167 fatal("internal error, bad protocol version %d", version); 168 return &idtable[version]; 169 } 170 171 static void 172 free_identity(Identity *id) 173 { 174 key_free(id->key); 175 xfree(id->comment); 176 xfree(id); 177 } 178 179 /* return matching private key for given public key */ 180 static Identity * 181 lookup_identity(Key *key, int version) 182 { 183 Identity *id; 184 185 Idtab *tab = idtab_lookup(version); 186 TAILQ_FOREACH(id, &tab->idlist, next) { 187 if (key_equal(key, id->key)) 188 return (id); 189 } 190 return (NULL); 191 } 192 193 /* Check confirmation of keysign request */ 194 static int 195 confirm_key(Identity *id) 196 { 197 char *p; 198 int ret = -1; 199 200 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 201 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.", 202 id->comment, p)) 203 ret = 0; 204 xfree(p); 205 206 return (ret); 207 } 208 209 /* send list of supported public keys to 'client' */ 210 static void 211 process_request_identities(SocketEntry *e, int version) 212 { 213 Idtab *tab = idtab_lookup(version); 214 Identity *id; 215 Buffer msg; 216 217 buffer_init(&msg); 218 buffer_put_char(&msg, (version == 1) ? 219 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 220 buffer_put_int(&msg, tab->nentries); 221 TAILQ_FOREACH(id, &tab->idlist, next) { 222 if (id->key->type == KEY_RSA1) { 223 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 224 buffer_put_bignum(&msg, id->key->rsa->e); 225 buffer_put_bignum(&msg, id->key->rsa->n); 226 } else { 227 u_char *blob; 228 u_int blen; 229 key_to_blob(id->key, &blob, &blen); 230 buffer_put_string(&msg, blob, blen); 231 xfree(blob); 232 } 233 buffer_put_cstring(&msg, id->comment); 234 } 235 buffer_put_int(&e->output, buffer_len(&msg)); 236 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 237 buffer_free(&msg); 238 } 239 240 /* ssh1 only */ 241 static void 242 process_authentication_challenge1(SocketEntry *e) 243 { 244 u_char buf[32], mdbuf[16], session_id[16]; 245 u_int response_type; 246 BIGNUM *challenge; 247 Identity *id; 248 int i, len; 249 Buffer msg; 250 MD5_CTX md; 251 Key *key; 252 253 buffer_init(&msg); 254 key = key_new(KEY_RSA1); 255 if ((challenge = BN_new()) == NULL) 256 fatal("process_authentication_challenge1: BN_new failed"); 257 258 (void) buffer_get_int(&e->request); /* ignored */ 259 buffer_get_bignum(&e->request, key->rsa->e); 260 buffer_get_bignum(&e->request, key->rsa->n); 261 buffer_get_bignum(&e->request, challenge); 262 263 /* Only protocol 1.1 is supported */ 264 if (buffer_len(&e->request) == 0) 265 goto failure; 266 buffer_get(&e->request, session_id, 16); 267 response_type = buffer_get_int(&e->request); 268 if (response_type != 1) 269 goto failure; 270 271 id = lookup_identity(key, 1); 272 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 273 Key *private = id->key; 274 /* Decrypt the challenge using the private key. */ 275 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 276 goto failure; 277 278 /* The response is MD5 of decrypted challenge plus session id. */ 279 len = BN_num_bytes(challenge); 280 if (len <= 0 || len > 32) { 281 logit("process_authentication_challenge: bad challenge length %d", len); 282 goto failure; 283 } 284 memset(buf, 0, 32); 285 BN_bn2bin(challenge, buf + 32 - len); 286 MD5_Init(&md); 287 MD5_Update(&md, buf, 32); 288 MD5_Update(&md, session_id, 16); 289 MD5_Final(mdbuf, &md); 290 291 /* Send the response. */ 292 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 293 for (i = 0; i < 16; i++) 294 buffer_put_char(&msg, mdbuf[i]); 295 goto send; 296 } 297 298 failure: 299 /* Unknown identity or protocol error. Send failure. */ 300 buffer_put_char(&msg, SSH_AGENT_FAILURE); 301 send: 302 buffer_put_int(&e->output, buffer_len(&msg)); 303 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 304 key_free(key); 305 BN_clear_free(challenge); 306 buffer_free(&msg); 307 } 308 309 /* ssh2 only */ 310 static void 311 process_sign_request2(SocketEntry *e) 312 { 313 u_char *blob, *data, *signature = NULL; 314 u_int blen, dlen, slen = 0; 315 extern int datafellows; 316 int odatafellows; 317 int ok = -1, flags; 318 Buffer msg; 319 Key *key; 320 321 datafellows = 0; 322 323 blob = buffer_get_string(&e->request, &blen); 324 data = buffer_get_string(&e->request, &dlen); 325 326 flags = buffer_get_int(&e->request); 327 odatafellows = datafellows; 328 if (flags & SSH_AGENT_OLD_SIGNATURE) 329 datafellows = SSH_BUG_SIGBLOB; 330 331 key = key_from_blob(blob, blen); 332 if (key != NULL) { 333 Identity *id = lookup_identity(key, 2); 334 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 335 ok = key_sign(id->key, &signature, &slen, data, dlen); 336 key_free(key); 337 } 338 buffer_init(&msg); 339 if (ok == 0) { 340 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 341 buffer_put_string(&msg, signature, slen); 342 } else { 343 buffer_put_char(&msg, SSH_AGENT_FAILURE); 344 } 345 buffer_put_int(&e->output, buffer_len(&msg)); 346 buffer_append(&e->output, buffer_ptr(&msg), 347 buffer_len(&msg)); 348 buffer_free(&msg); 349 xfree(data); 350 xfree(blob); 351 if (signature != NULL) 352 xfree(signature); 353 datafellows = odatafellows; 354 } 355 356 /* shared */ 357 static void 358 process_remove_identity(SocketEntry *e, int version) 359 { 360 u_int blen, bits; 361 int success = 0; 362 Key *key = NULL; 363 u_char *blob; 364 365 switch (version) { 366 case 1: 367 key = key_new(KEY_RSA1); 368 bits = buffer_get_int(&e->request); 369 buffer_get_bignum(&e->request, key->rsa->e); 370 buffer_get_bignum(&e->request, key->rsa->n); 371 372 if (bits != key_size(key)) 373 logit("Warning: identity keysize mismatch: actual %u, announced %u", 374 key_size(key), bits); 375 break; 376 case 2: 377 blob = buffer_get_string(&e->request, &blen); 378 key = key_from_blob(blob, blen); 379 xfree(blob); 380 break; 381 } 382 if (key != NULL) { 383 Identity *id = lookup_identity(key, version); 384 if (id != NULL) { 385 /* 386 * We have this key. Free the old key. Since we 387 * don't want to leave empty slots in the middle of 388 * the array, we actually free the key there and move 389 * all the entries between the empty slot and the end 390 * of the array. 391 */ 392 Idtab *tab = idtab_lookup(version); 393 if (tab->nentries < 1) 394 fatal("process_remove_identity: " 395 "internal error: tab->nentries %d", 396 tab->nentries); 397 TAILQ_REMOVE(&tab->idlist, id, next); 398 free_identity(id); 399 tab->nentries--; 400 success = 1; 401 } 402 key_free(key); 403 } 404 buffer_put_int(&e->output, 1); 405 buffer_put_char(&e->output, 406 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 407 } 408 409 static void 410 process_remove_all_identities(SocketEntry *e, int version) 411 { 412 Idtab *tab = idtab_lookup(version); 413 Identity *id; 414 415 /* Loop over all identities and clear the keys. */ 416 for (id = TAILQ_FIRST(&tab->idlist); id; 417 id = TAILQ_FIRST(&tab->idlist)) { 418 TAILQ_REMOVE(&tab->idlist, id, next); 419 free_identity(id); 420 } 421 422 /* Mark that there are no identities. */ 423 tab->nentries = 0; 424 425 /* Send success. */ 426 buffer_put_int(&e->output, 1); 427 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 428 } 429 430 /* removes expired keys and returns number of seconds until the next expiry */ 431 static u_int 432 reaper(void) 433 { 434 u_int deadline = 0, now = time(NULL); 435 Identity *id, *nxt; 436 int version; 437 Idtab *tab; 438 439 for (version = 1; version < 3; version++) { 440 tab = idtab_lookup(version); 441 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 442 nxt = TAILQ_NEXT(id, next); 443 if (id->death == 0) 444 continue; 445 if (now >= id->death) { 446 debug("expiring key '%s'", id->comment); 447 TAILQ_REMOVE(&tab->idlist, id, next); 448 free_identity(id); 449 tab->nentries--; 450 } else 451 deadline = (deadline == 0) ? id->death : 452 MIN(deadline, id->death); 453 } 454 } 455 if (deadline == 0 || deadline <= now) 456 return 0; 457 else 458 return (deadline - now); 459 } 460 461 static void 462 process_add_identity(SocketEntry *e, int version) 463 { 464 Idtab *tab = idtab_lookup(version); 465 Identity *id; 466 int type, success = 0, death = 0, confirm = 0; 467 char *type_name, *comment; 468 Key *k = NULL; 469 470 switch (version) { 471 case 1: 472 k = key_new_private(KEY_RSA1); 473 (void) buffer_get_int(&e->request); /* ignored */ 474 buffer_get_bignum(&e->request, k->rsa->n); 475 buffer_get_bignum(&e->request, k->rsa->e); 476 buffer_get_bignum(&e->request, k->rsa->d); 477 buffer_get_bignum(&e->request, k->rsa->iqmp); 478 479 /* SSH and SSL have p and q swapped */ 480 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 481 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 482 483 /* Generate additional parameters */ 484 rsa_generate_additional_parameters(k->rsa); 485 break; 486 case 2: 487 type_name = buffer_get_string(&e->request, NULL); 488 type = key_type_from_name(type_name); 489 xfree(type_name); 490 switch (type) { 491 case KEY_DSA: 492 k = key_new_private(type); 493 buffer_get_bignum2(&e->request, k->dsa->p); 494 buffer_get_bignum2(&e->request, k->dsa->q); 495 buffer_get_bignum2(&e->request, k->dsa->g); 496 buffer_get_bignum2(&e->request, k->dsa->pub_key); 497 buffer_get_bignum2(&e->request, k->dsa->priv_key); 498 break; 499 case KEY_RSA: 500 k = key_new_private(type); 501 buffer_get_bignum2(&e->request, k->rsa->n); 502 buffer_get_bignum2(&e->request, k->rsa->e); 503 buffer_get_bignum2(&e->request, k->rsa->d); 504 buffer_get_bignum2(&e->request, k->rsa->iqmp); 505 buffer_get_bignum2(&e->request, k->rsa->p); 506 buffer_get_bignum2(&e->request, k->rsa->q); 507 508 /* Generate additional parameters */ 509 rsa_generate_additional_parameters(k->rsa); 510 break; 511 default: 512 buffer_clear(&e->request); 513 goto send; 514 } 515 break; 516 } 517 /* enable blinding */ 518 switch (k->type) { 519 case KEY_RSA: 520 case KEY_RSA1: 521 if (RSA_blinding_on(k->rsa, NULL) != 1) { 522 error("process_add_identity: RSA_blinding_on failed"); 523 key_free(k); 524 goto send; 525 } 526 break; 527 } 528 comment = buffer_get_string(&e->request, NULL); 529 if (k == NULL) { 530 xfree(comment); 531 goto send; 532 } 533 while (buffer_len(&e->request)) { 534 switch ((type = buffer_get_char(&e->request))) { 535 case SSH_AGENT_CONSTRAIN_LIFETIME: 536 death = time(NULL) + buffer_get_int(&e->request); 537 break; 538 case SSH_AGENT_CONSTRAIN_CONFIRM: 539 confirm = 1; 540 break; 541 default: 542 error("process_add_identity: " 543 "Unknown constraint type %d", type); 544 xfree(comment); 545 key_free(k); 546 goto send; 547 } 548 } 549 success = 1; 550 if (lifetime && !death) 551 death = time(NULL) + lifetime; 552 if ((id = lookup_identity(k, version)) == NULL) { 553 id = xmalloc(sizeof(Identity)); 554 id->key = k; 555 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 556 /* Increment the number of identities. */ 557 tab->nentries++; 558 } else { 559 key_free(k); 560 xfree(id->comment); 561 } 562 id->comment = comment; 563 id->death = death; 564 id->confirm = confirm; 565 send: 566 buffer_put_int(&e->output, 1); 567 buffer_put_char(&e->output, 568 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 569 } 570 571 /* XXX todo: encrypt sensitive data with passphrase */ 572 static void 573 process_lock_agent(SocketEntry *e, int lock) 574 { 575 int success = 0; 576 char *passwd; 577 578 passwd = buffer_get_string(&e->request, NULL); 579 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 580 locked = 0; 581 memset(lock_passwd, 0, strlen(lock_passwd)); 582 xfree(lock_passwd); 583 lock_passwd = NULL; 584 success = 1; 585 } else if (!locked && lock) { 586 locked = 1; 587 lock_passwd = xstrdup(passwd); 588 success = 1; 589 } 590 memset(passwd, 0, strlen(passwd)); 591 xfree(passwd); 592 593 buffer_put_int(&e->output, 1); 594 buffer_put_char(&e->output, 595 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 596 } 597 598 static void 599 no_identities(SocketEntry *e, u_int type) 600 { 601 Buffer msg; 602 603 buffer_init(&msg); 604 buffer_put_char(&msg, 605 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 606 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 607 buffer_put_int(&msg, 0); 608 buffer_put_int(&e->output, buffer_len(&msg)); 609 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 610 buffer_free(&msg); 611 } 612 613 #ifdef SMARTCARD 614 static void 615 process_add_smartcard_key(SocketEntry *e) 616 { 617 char *sc_reader_id = NULL, *pin; 618 int i, type, version, success = 0, death = 0, confirm = 0; 619 Key **keys, *k; 620 Identity *id; 621 Idtab *tab; 622 623 sc_reader_id = buffer_get_string(&e->request, NULL); 624 pin = buffer_get_string(&e->request, NULL); 625 626 while (buffer_len(&e->request)) { 627 switch ((type = buffer_get_char(&e->request))) { 628 case SSH_AGENT_CONSTRAIN_LIFETIME: 629 death = time(NULL) + buffer_get_int(&e->request); 630 break; 631 case SSH_AGENT_CONSTRAIN_CONFIRM: 632 confirm = 1; 633 break; 634 default: 635 error("process_add_smartcard_key: " 636 "Unknown constraint type %d", type); 637 xfree(sc_reader_id); 638 xfree(pin); 639 goto send; 640 } 641 } 642 if (lifetime && !death) 643 death = time(NULL) + lifetime; 644 645 keys = sc_get_keys(sc_reader_id, pin); 646 xfree(sc_reader_id); 647 xfree(pin); 648 649 if (keys == NULL || keys[0] == NULL) { 650 error("sc_get_keys failed"); 651 goto send; 652 } 653 for (i = 0; keys[i] != NULL; i++) { 654 k = keys[i]; 655 version = k->type == KEY_RSA1 ? 1 : 2; 656 tab = idtab_lookup(version); 657 if (lookup_identity(k, version) == NULL) { 658 id = xmalloc(sizeof(Identity)); 659 id->key = k; 660 id->comment = sc_get_key_label(k); 661 id->death = death; 662 id->confirm = confirm; 663 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 664 tab->nentries++; 665 success = 1; 666 } else { 667 key_free(k); 668 } 669 keys[i] = NULL; 670 } 671 xfree(keys); 672 send: 673 buffer_put_int(&e->output, 1); 674 buffer_put_char(&e->output, 675 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 676 } 677 678 static void 679 process_remove_smartcard_key(SocketEntry *e) 680 { 681 char *sc_reader_id = NULL, *pin; 682 int i, version, success = 0; 683 Key **keys, *k = NULL; 684 Identity *id; 685 Idtab *tab; 686 687 sc_reader_id = buffer_get_string(&e->request, NULL); 688 pin = buffer_get_string(&e->request, NULL); 689 keys = sc_get_keys(sc_reader_id, pin); 690 xfree(sc_reader_id); 691 xfree(pin); 692 693 if (keys == NULL || keys[0] == NULL) { 694 error("sc_get_keys failed"); 695 goto send; 696 } 697 for (i = 0; keys[i] != NULL; i++) { 698 k = keys[i]; 699 version = k->type == KEY_RSA1 ? 1 : 2; 700 if ((id = lookup_identity(k, version)) != NULL) { 701 tab = idtab_lookup(version); 702 TAILQ_REMOVE(&tab->idlist, id, next); 703 tab->nentries--; 704 free_identity(id); 705 success = 1; 706 } 707 key_free(k); 708 keys[i] = NULL; 709 } 710 xfree(keys); 711 send: 712 buffer_put_int(&e->output, 1); 713 buffer_put_char(&e->output, 714 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 715 } 716 #endif /* SMARTCARD */ 717 718 /* dispatch incoming messages */ 719 720 static void 721 process_message(SocketEntry *e) 722 { 723 u_int msg_len, type; 724 u_char *cp; 725 726 if (buffer_len(&e->input) < 5) 727 return; /* Incomplete message. */ 728 cp = buffer_ptr(&e->input); 729 msg_len = get_u32(cp); 730 if (msg_len > 256 * 1024) { 731 close_socket(e); 732 return; 733 } 734 if (buffer_len(&e->input) < msg_len + 4) 735 return; 736 737 /* move the current input to e->request */ 738 buffer_consume(&e->input, 4); 739 buffer_clear(&e->request); 740 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 741 buffer_consume(&e->input, msg_len); 742 type = buffer_get_char(&e->request); 743 744 /* check wheter agent is locked */ 745 if (locked && type != SSH_AGENTC_UNLOCK) { 746 buffer_clear(&e->request); 747 switch (type) { 748 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 749 case SSH2_AGENTC_REQUEST_IDENTITIES: 750 /* send empty lists */ 751 no_identities(e, type); 752 break; 753 default: 754 /* send a fail message for all other request types */ 755 buffer_put_int(&e->output, 1); 756 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 757 } 758 return; 759 } 760 761 debug("type %d", type); 762 switch (type) { 763 case SSH_AGENTC_LOCK: 764 case SSH_AGENTC_UNLOCK: 765 process_lock_agent(e, type == SSH_AGENTC_LOCK); 766 break; 767 /* ssh1 */ 768 case SSH_AGENTC_RSA_CHALLENGE: 769 process_authentication_challenge1(e); 770 break; 771 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 772 process_request_identities(e, 1); 773 break; 774 case SSH_AGENTC_ADD_RSA_IDENTITY: 775 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 776 process_add_identity(e, 1); 777 break; 778 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 779 process_remove_identity(e, 1); 780 break; 781 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 782 process_remove_all_identities(e, 1); 783 break; 784 /* ssh2 */ 785 case SSH2_AGENTC_SIGN_REQUEST: 786 process_sign_request2(e); 787 break; 788 case SSH2_AGENTC_REQUEST_IDENTITIES: 789 process_request_identities(e, 2); 790 break; 791 case SSH2_AGENTC_ADD_IDENTITY: 792 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 793 process_add_identity(e, 2); 794 break; 795 case SSH2_AGENTC_REMOVE_IDENTITY: 796 process_remove_identity(e, 2); 797 break; 798 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 799 process_remove_all_identities(e, 2); 800 break; 801 #ifdef SMARTCARD 802 case SSH_AGENTC_ADD_SMARTCARD_KEY: 803 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 804 process_add_smartcard_key(e); 805 break; 806 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 807 process_remove_smartcard_key(e); 808 break; 809 #endif /* SMARTCARD */ 810 default: 811 /* Unknown message. Respond with failure. */ 812 error("Unknown message %d", type); 813 buffer_clear(&e->request); 814 buffer_put_int(&e->output, 1); 815 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 816 break; 817 } 818 } 819 820 static void 821 new_socket(sock_type type, int fd) 822 { 823 u_int i, old_alloc, new_alloc; 824 825 set_nonblock(fd); 826 827 if (fd > max_fd) 828 max_fd = fd; 829 830 for (i = 0; i < sockets_alloc; i++) 831 if (sockets[i].type == AUTH_UNUSED) { 832 sockets[i].fd = fd; 833 buffer_init(&sockets[i].input); 834 buffer_init(&sockets[i].output); 835 buffer_init(&sockets[i].request); 836 sockets[i].type = type; 837 return; 838 } 839 old_alloc = sockets_alloc; 840 new_alloc = sockets_alloc + 10; 841 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0])); 842 for (i = old_alloc; i < new_alloc; i++) 843 sockets[i].type = AUTH_UNUSED; 844 sockets_alloc = new_alloc; 845 sockets[old_alloc].fd = fd; 846 buffer_init(&sockets[old_alloc].input); 847 buffer_init(&sockets[old_alloc].output); 848 buffer_init(&sockets[old_alloc].request); 849 sockets[old_alloc].type = type; 850 } 851 852 static int 853 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp, 854 struct timeval **tvpp) 855 { 856 u_int i, sz, deadline; 857 int n = 0; 858 static struct timeval tv; 859 860 for (i = 0; i < sockets_alloc; i++) { 861 switch (sockets[i].type) { 862 case AUTH_SOCKET: 863 case AUTH_CONNECTION: 864 n = MAX(n, sockets[i].fd); 865 break; 866 case AUTH_UNUSED: 867 break; 868 default: 869 fatal("Unknown socket type %d", sockets[i].type); 870 break; 871 } 872 } 873 874 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 875 if (*fdrp == NULL || sz > *nallocp) { 876 if (*fdrp) 877 xfree(*fdrp); 878 if (*fdwp) 879 xfree(*fdwp); 880 *fdrp = xmalloc(sz); 881 *fdwp = xmalloc(sz); 882 *nallocp = sz; 883 } 884 if (n < *fdl) 885 debug("XXX shrink: %d < %d", n, *fdl); 886 *fdl = n; 887 memset(*fdrp, 0, sz); 888 memset(*fdwp, 0, sz); 889 890 for (i = 0; i < sockets_alloc; i++) { 891 switch (sockets[i].type) { 892 case AUTH_SOCKET: 893 case AUTH_CONNECTION: 894 FD_SET(sockets[i].fd, *fdrp); 895 if (buffer_len(&sockets[i].output) > 0) 896 FD_SET(sockets[i].fd, *fdwp); 897 break; 898 default: 899 break; 900 } 901 } 902 deadline = reaper(); 903 if (parent_alive_interval != 0) 904 deadline = (deadline == 0) ? parent_alive_interval : 905 MIN(deadline, parent_alive_interval); 906 if (deadline == 0) { 907 *tvpp = NULL; 908 } else { 909 tv.tv_sec = deadline; 910 tv.tv_usec = 0; 911 *tvpp = &tv; 912 } 913 return (1); 914 } 915 916 static void 917 after_select(fd_set *readset, fd_set *writeset) 918 { 919 struct sockaddr_un sunaddr; 920 socklen_t slen; 921 char buf[1024]; 922 int len, sock; 923 u_int i; 924 uid_t euid; 925 gid_t egid; 926 927 for (i = 0; i < sockets_alloc; i++) 928 switch (sockets[i].type) { 929 case AUTH_UNUSED: 930 break; 931 case AUTH_SOCKET: 932 if (FD_ISSET(sockets[i].fd, readset)) { 933 slen = sizeof(sunaddr); 934 sock = accept(sockets[i].fd, 935 (struct sockaddr *)&sunaddr, &slen); 936 if (sock < 0) { 937 error("accept from AUTH_SOCKET: %s", 938 strerror(errno)); 939 break; 940 } 941 if (getpeereid(sock, &euid, &egid) < 0) { 942 error("getpeereid %d failed: %s", 943 sock, strerror(errno)); 944 close(sock); 945 break; 946 } 947 if ((euid != 0) && (getuid() != euid)) { 948 error("uid mismatch: " 949 "peer euid %u != uid %u", 950 (u_int) euid, (u_int) getuid()); 951 close(sock); 952 break; 953 } 954 new_socket(AUTH_CONNECTION, sock); 955 } 956 break; 957 case AUTH_CONNECTION: 958 if (buffer_len(&sockets[i].output) > 0 && 959 FD_ISSET(sockets[i].fd, writeset)) { 960 do { 961 len = write(sockets[i].fd, 962 buffer_ptr(&sockets[i].output), 963 buffer_len(&sockets[i].output)); 964 if (len == -1 && (errno == EAGAIN || 965 errno == EINTR || 966 errno == EWOULDBLOCK)) 967 continue; 968 break; 969 } while (1); 970 if (len <= 0) { 971 close_socket(&sockets[i]); 972 break; 973 } 974 buffer_consume(&sockets[i].output, len); 975 } 976 if (FD_ISSET(sockets[i].fd, readset)) { 977 do { 978 len = read(sockets[i].fd, buf, sizeof(buf)); 979 if (len == -1 && (errno == EAGAIN || 980 errno == EINTR || 981 errno == EWOULDBLOCK)) 982 continue; 983 break; 984 } while (1); 985 if (len <= 0) { 986 close_socket(&sockets[i]); 987 break; 988 } 989 buffer_append(&sockets[i].input, buf, len); 990 process_message(&sockets[i]); 991 } 992 break; 993 default: 994 fatal("Unknown type %d", sockets[i].type); 995 } 996 } 997 998 static void 999 cleanup_socket(void) 1000 { 1001 if (socket_name[0]) 1002 unlink(socket_name); 1003 if (socket_dir[0]) 1004 rmdir(socket_dir); 1005 } 1006 1007 void 1008 cleanup_exit(int i) 1009 { 1010 cleanup_socket(); 1011 _exit(i); 1012 } 1013 1014 /*ARGSUSED*/ 1015 static void 1016 cleanup_handler(int sig) 1017 { 1018 cleanup_socket(); 1019 _exit(2); 1020 } 1021 1022 static void 1023 check_parent_exists(void) 1024 { 1025 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 1026 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1027 cleanup_socket(); 1028 _exit(2); 1029 } 1030 } 1031 1032 static void 1033 usage(void) 1034 { 1035 fprintf(stderr, "usage: %s [options] [command [arg ...]]\n", 1036 __progname); 1037 fprintf(stderr, "Options:\n"); 1038 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 1039 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 1040 fprintf(stderr, " -k Kill the current agent.\n"); 1041 fprintf(stderr, " -d Debug mode.\n"); 1042 fprintf(stderr, " -a socket Bind agent socket to given name.\n"); 1043 fprintf(stderr, " -t life Default identity lifetime (seconds).\n"); 1044 exit(1); 1045 } 1046 1047 int 1048 main(int ac, char **av) 1049 { 1050 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1051 int sock, fd, ch, result, saved_errno; 1052 u_int nalloc; 1053 char *shell, *format, *pidstr, *agentsocket = NULL; 1054 fd_set *readsetp = NULL, *writesetp = NULL; 1055 struct sockaddr_un sunaddr; 1056 #ifdef HAVE_SETRLIMIT 1057 struct rlimit rlim; 1058 #endif 1059 int prev_mask; 1060 extern int optind; 1061 extern char *optarg; 1062 pid_t pid; 1063 char pidstrbuf[1 + 3 * sizeof pid]; 1064 struct timeval *tvp = NULL; 1065 1066 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1067 sanitise_stdfd(); 1068 1069 /* drop */ 1070 setegid(getgid()); 1071 setgid(getgid()); 1072 setuid(geteuid()); 1073 1074 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) 1075 /* Disable ptrace on Linux without sgid bit */ 1076 prctl(PR_SET_DUMPABLE, 0); 1077 #endif 1078 1079 SSLeay_add_all_algorithms(); 1080 1081 __progname = ssh_get_progname(av[0]); 1082 init_rng(); 1083 seed_rng(); 1084 1085 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) { 1086 switch (ch) { 1087 case 'c': 1088 if (s_flag) 1089 usage(); 1090 c_flag++; 1091 break; 1092 case 'k': 1093 k_flag++; 1094 break; 1095 case 's': 1096 if (c_flag) 1097 usage(); 1098 s_flag++; 1099 break; 1100 case 'd': 1101 if (d_flag) 1102 usage(); 1103 d_flag++; 1104 break; 1105 case 'a': 1106 agentsocket = optarg; 1107 break; 1108 case 't': 1109 if ((lifetime = convtime(optarg)) == -1) { 1110 fprintf(stderr, "Invalid lifetime\n"); 1111 usage(); 1112 } 1113 break; 1114 default: 1115 usage(); 1116 } 1117 } 1118 ac -= optind; 1119 av += optind; 1120 1121 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1122 usage(); 1123 1124 if (ac == 0 && !c_flag && !s_flag) { 1125 shell = getenv("SHELL"); 1126 if (shell != NULL && 1127 strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 1128 c_flag = 1; 1129 } 1130 if (k_flag) { 1131 const char *errstr = NULL; 1132 1133 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1134 if (pidstr == NULL) { 1135 fprintf(stderr, "%s not set, cannot kill agent\n", 1136 SSH_AGENTPID_ENV_NAME); 1137 exit(1); 1138 } 1139 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1140 if (errstr) { 1141 fprintf(stderr, 1142 "%s=\"%s\", which is not a good PID: %s\n", 1143 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1144 exit(1); 1145 } 1146 if (kill(pid, SIGTERM) == -1) { 1147 perror("kill"); 1148 exit(1); 1149 } 1150 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1151 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1152 printf(format, SSH_AGENTPID_ENV_NAME); 1153 printf("echo Agent pid %ld killed;\n", (long)pid); 1154 exit(0); 1155 } 1156 parent_pid = getpid(); 1157 1158 if (agentsocket == NULL) { 1159 /* Create private directory for agent socket */ 1160 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir); 1161 if (mkdtemp(socket_dir) == NULL) { 1162 perror("mkdtemp: private socket dir"); 1163 exit(1); 1164 } 1165 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1166 (long)parent_pid); 1167 } else { 1168 /* Try to use specified agent socket */ 1169 socket_dir[0] = '\0'; 1170 strlcpy(socket_name, agentsocket, sizeof socket_name); 1171 } 1172 1173 /* 1174 * Create socket early so it will exist before command gets run from 1175 * the parent. 1176 */ 1177 sock = socket(AF_UNIX, SOCK_STREAM, 0); 1178 if (sock < 0) { 1179 perror("socket"); 1180 *socket_name = '\0'; /* Don't unlink any existing file */ 1181 cleanup_exit(1); 1182 } 1183 memset(&sunaddr, 0, sizeof(sunaddr)); 1184 sunaddr.sun_family = AF_UNIX; 1185 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 1186 prev_mask = umask(0177); 1187 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) { 1188 perror("bind"); 1189 *socket_name = '\0'; /* Don't unlink any existing file */ 1190 umask(prev_mask); 1191 cleanup_exit(1); 1192 } 1193 umask(prev_mask); 1194 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 1195 perror("listen"); 1196 cleanup_exit(1); 1197 } 1198 1199 /* 1200 * Fork, and have the parent execute the command, if any, or present 1201 * the socket data. The child continues as the authentication agent. 1202 */ 1203 if (d_flag) { 1204 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1205 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1206 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1207 SSH_AUTHSOCKET_ENV_NAME); 1208 printf("echo Agent pid %ld;\n", (long)parent_pid); 1209 goto skip; 1210 } 1211 pid = fork(); 1212 if (pid == -1) { 1213 perror("fork"); 1214 cleanup_exit(1); 1215 } 1216 if (pid != 0) { /* Parent - execute the given command. */ 1217 close(sock); 1218 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1219 if (ac == 0) { 1220 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1221 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1222 SSH_AUTHSOCKET_ENV_NAME); 1223 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1224 SSH_AGENTPID_ENV_NAME); 1225 printf("echo Agent pid %ld;\n", (long)pid); 1226 exit(0); 1227 } 1228 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1229 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1230 perror("setenv"); 1231 exit(1); 1232 } 1233 execvp(av[0], av); 1234 perror(av[0]); 1235 exit(1); 1236 } 1237 /* child */ 1238 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1239 1240 if (setsid() == -1) { 1241 error("setsid: %s", strerror(errno)); 1242 cleanup_exit(1); 1243 } 1244 1245 (void)chdir("/"); 1246 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1247 /* XXX might close listen socket */ 1248 (void)dup2(fd, STDIN_FILENO); 1249 (void)dup2(fd, STDOUT_FILENO); 1250 (void)dup2(fd, STDERR_FILENO); 1251 if (fd > 2) 1252 close(fd); 1253 } 1254 1255 #ifdef HAVE_SETRLIMIT 1256 /* deny core dumps, since memory contains unencrypted private keys */ 1257 rlim.rlim_cur = rlim.rlim_max = 0; 1258 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1259 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1260 cleanup_exit(1); 1261 } 1262 #endif 1263 1264 skip: 1265 new_socket(AUTH_SOCKET, sock); 1266 if (ac > 0) 1267 parent_alive_interval = 10; 1268 idtab_init(); 1269 if (!d_flag) 1270 signal(SIGINT, SIG_IGN); 1271 signal(SIGPIPE, 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