1 /* $OpenBSD: ssh-agent.c,v 1.153 2006/10/06 02:29:19 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 <sys/types.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 #include <sys/resource.h> 41 #include <sys/types.h> 42 #include <sys/socket.h> 43 #include <sys/un.h> 44 #include <sys/param.h> 45 46 #include <openssl/evp.h> 47 #include <openssl/md5.h> 48 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <paths.h> 52 #include <signal.h> 53 #include <stdlib.h> 54 #include <stdio.h> 55 #include <string.h> 56 #include <time.h> 57 #include <unistd.h> 58 59 #include "xmalloc.h" 60 #include "ssh.h" 61 #include "rsa.h" 62 #include "buffer.h" 63 #include "key.h" 64 #include "authfd.h" 65 #include "compat.h" 66 #include "log.h" 67 #include "misc.h" 68 69 #ifdef SMARTCARD 70 #include "scard.h" 71 #endif 72 73 typedef enum { 74 AUTH_UNUSED, 75 AUTH_SOCKET, 76 AUTH_CONNECTION 77 } sock_type; 78 79 typedef struct { 80 int fd; 81 sock_type type; 82 Buffer input; 83 Buffer output; 84 Buffer request; 85 } SocketEntry; 86 87 u_int sockets_alloc = 0; 88 SocketEntry *sockets = NULL; 89 90 typedef struct identity { 91 TAILQ_ENTRY(identity) next; 92 Key *key; 93 char *comment; 94 u_int death; 95 u_int confirm; 96 } Identity; 97 98 typedef struct { 99 int nentries; 100 TAILQ_HEAD(idqueue, identity) idlist; 101 } Idtab; 102 103 /* private key table, one per protocol version */ 104 Idtab idtable[3]; 105 106 int max_fd = 0; 107 108 /* pid of shell == parent of agent */ 109 pid_t parent_pid = -1; 110 111 /* pathname and directory for AUTH_SOCKET */ 112 char socket_name[MAXPATHLEN]; 113 char socket_dir[MAXPATHLEN]; 114 115 /* locking */ 116 int locked = 0; 117 char *lock_passwd = NULL; 118 119 extern char *__progname; 120 121 /* Default lifetime (0 == forever) */ 122 static int lifetime = 0; 123 124 static void 125 close_socket(SocketEntry *e) 126 { 127 close(e->fd); 128 e->fd = -1; 129 e->type = AUTH_UNUSED; 130 buffer_free(&e->input); 131 buffer_free(&e->output); 132 buffer_free(&e->request); 133 } 134 135 static void 136 idtab_init(void) 137 { 138 int i; 139 140 for (i = 0; i <=2; i++) { 141 TAILQ_INIT(&idtable[i].idlist); 142 idtable[i].nentries = 0; 143 } 144 } 145 146 /* return private key table for requested protocol version */ 147 static Idtab * 148 idtab_lookup(int version) 149 { 150 if (version < 1 || version > 2) 151 fatal("internal error, bad protocol version %d", version); 152 return &idtable[version]; 153 } 154 155 static void 156 free_identity(Identity *id) 157 { 158 key_free(id->key); 159 xfree(id->comment); 160 xfree(id); 161 } 162 163 /* return matching private key for given public key */ 164 static Identity * 165 lookup_identity(Key *key, int version) 166 { 167 Identity *id; 168 169 Idtab *tab = idtab_lookup(version); 170 TAILQ_FOREACH(id, &tab->idlist, next) { 171 if (key_equal(key, id->key)) 172 return (id); 173 } 174 return (NULL); 175 } 176 177 /* Check confirmation of keysign request */ 178 static int 179 confirm_key(Identity *id) 180 { 181 char *p; 182 int ret = -1; 183 184 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 185 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.", 186 id->comment, p)) 187 ret = 0; 188 xfree(p); 189 190 return (ret); 191 } 192 193 /* send list of supported public keys to 'client' */ 194 static void 195 process_request_identities(SocketEntry *e, int version) 196 { 197 Idtab *tab = idtab_lookup(version); 198 Identity *id; 199 Buffer msg; 200 201 buffer_init(&msg); 202 buffer_put_char(&msg, (version == 1) ? 203 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 204 buffer_put_int(&msg, tab->nentries); 205 TAILQ_FOREACH(id, &tab->idlist, next) { 206 if (id->key->type == KEY_RSA1) { 207 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 208 buffer_put_bignum(&msg, id->key->rsa->e); 209 buffer_put_bignum(&msg, id->key->rsa->n); 210 } else { 211 u_char *blob; 212 u_int blen; 213 key_to_blob(id->key, &blob, &blen); 214 buffer_put_string(&msg, blob, blen); 215 xfree(blob); 216 } 217 buffer_put_cstring(&msg, id->comment); 218 } 219 buffer_put_int(&e->output, buffer_len(&msg)); 220 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 221 buffer_free(&msg); 222 } 223 224 /* ssh1 only */ 225 static void 226 process_authentication_challenge1(SocketEntry *e) 227 { 228 u_char buf[32], mdbuf[16], session_id[16]; 229 u_int response_type; 230 BIGNUM *challenge; 231 Identity *id; 232 int i, len; 233 Buffer msg; 234 MD5_CTX md; 235 Key *key; 236 237 buffer_init(&msg); 238 key = key_new(KEY_RSA1); 239 if ((challenge = BN_new()) == NULL) 240 fatal("process_authentication_challenge1: BN_new failed"); 241 242 (void) buffer_get_int(&e->request); /* ignored */ 243 buffer_get_bignum(&e->request, key->rsa->e); 244 buffer_get_bignum(&e->request, key->rsa->n); 245 buffer_get_bignum(&e->request, challenge); 246 247 /* Only protocol 1.1 is supported */ 248 if (buffer_len(&e->request) == 0) 249 goto failure; 250 buffer_get(&e->request, session_id, 16); 251 response_type = buffer_get_int(&e->request); 252 if (response_type != 1) 253 goto failure; 254 255 id = lookup_identity(key, 1); 256 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 257 Key *private = id->key; 258 /* Decrypt the challenge using the private key. */ 259 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 260 goto failure; 261 262 /* The response is MD5 of decrypted challenge plus session id. */ 263 len = BN_num_bytes(challenge); 264 if (len <= 0 || len > 32) { 265 logit("process_authentication_challenge: bad challenge length %d", len); 266 goto failure; 267 } 268 memset(buf, 0, 32); 269 BN_bn2bin(challenge, buf + 32 - len); 270 MD5_Init(&md); 271 MD5_Update(&md, buf, 32); 272 MD5_Update(&md, session_id, 16); 273 MD5_Final(mdbuf, &md); 274 275 /* Send the response. */ 276 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 277 for (i = 0; i < 16; i++) 278 buffer_put_char(&msg, mdbuf[i]); 279 goto send; 280 } 281 282 failure: 283 /* Unknown identity or protocol error. Send failure. */ 284 buffer_put_char(&msg, SSH_AGENT_FAILURE); 285 send: 286 buffer_put_int(&e->output, buffer_len(&msg)); 287 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 288 key_free(key); 289 BN_clear_free(challenge); 290 buffer_free(&msg); 291 } 292 293 /* ssh2 only */ 294 static void 295 process_sign_request2(SocketEntry *e) 296 { 297 u_char *blob, *data, *signature = NULL; 298 u_int blen, dlen, slen = 0; 299 extern int datafellows; 300 int ok = -1, flags; 301 Buffer msg; 302 Key *key; 303 304 datafellows = 0; 305 306 blob = buffer_get_string(&e->request, &blen); 307 data = buffer_get_string(&e->request, &dlen); 308 309 flags = buffer_get_int(&e->request); 310 if (flags & SSH_AGENT_OLD_SIGNATURE) 311 datafellows = SSH_BUG_SIGBLOB; 312 313 key = key_from_blob(blob, blen); 314 if (key != NULL) { 315 Identity *id = lookup_identity(key, 2); 316 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 317 ok = key_sign(id->key, &signature, &slen, data, dlen); 318 key_free(key); 319 } 320 buffer_init(&msg); 321 if (ok == 0) { 322 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 323 buffer_put_string(&msg, signature, slen); 324 } else { 325 buffer_put_char(&msg, SSH_AGENT_FAILURE); 326 } 327 buffer_put_int(&e->output, buffer_len(&msg)); 328 buffer_append(&e->output, buffer_ptr(&msg), 329 buffer_len(&msg)); 330 buffer_free(&msg); 331 xfree(data); 332 xfree(blob); 333 if (signature != NULL) 334 xfree(signature); 335 } 336 337 /* shared */ 338 static void 339 process_remove_identity(SocketEntry *e, int version) 340 { 341 u_int blen, bits; 342 int success = 0; 343 Key *key = NULL; 344 u_char *blob; 345 346 switch (version) { 347 case 1: 348 key = key_new(KEY_RSA1); 349 bits = buffer_get_int(&e->request); 350 buffer_get_bignum(&e->request, key->rsa->e); 351 buffer_get_bignum(&e->request, key->rsa->n); 352 353 if (bits != key_size(key)) 354 logit("Warning: identity keysize mismatch: actual %u, announced %u", 355 key_size(key), bits); 356 break; 357 case 2: 358 blob = buffer_get_string(&e->request, &blen); 359 key = key_from_blob(blob, blen); 360 xfree(blob); 361 break; 362 } 363 if (key != NULL) { 364 Identity *id = lookup_identity(key, version); 365 if (id != NULL) { 366 /* 367 * We have this key. Free the old key. Since we 368 * don't want to leave empty slots in the middle of 369 * the array, we actually free the key there and move 370 * all the entries between the empty slot and the end 371 * of the array. 372 */ 373 Idtab *tab = idtab_lookup(version); 374 if (tab->nentries < 1) 375 fatal("process_remove_identity: " 376 "internal error: tab->nentries %d", 377 tab->nentries); 378 TAILQ_REMOVE(&tab->idlist, id, next); 379 free_identity(id); 380 tab->nentries--; 381 success = 1; 382 } 383 key_free(key); 384 } 385 buffer_put_int(&e->output, 1); 386 buffer_put_char(&e->output, 387 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 388 } 389 390 static void 391 process_remove_all_identities(SocketEntry *e, int version) 392 { 393 Idtab *tab = idtab_lookup(version); 394 Identity *id; 395 396 /* Loop over all identities and clear the keys. */ 397 for (id = TAILQ_FIRST(&tab->idlist); id; 398 id = TAILQ_FIRST(&tab->idlist)) { 399 TAILQ_REMOVE(&tab->idlist, id, next); 400 free_identity(id); 401 } 402 403 /* Mark that there are no identities. */ 404 tab->nentries = 0; 405 406 /* Send success. */ 407 buffer_put_int(&e->output, 1); 408 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 409 } 410 411 static void 412 reaper(void) 413 { 414 u_int now = time(NULL); 415 Identity *id, *nxt; 416 int version; 417 Idtab *tab; 418 419 for (version = 1; version < 3; version++) { 420 tab = idtab_lookup(version); 421 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 422 nxt = TAILQ_NEXT(id, next); 423 if (id->death != 0 && now >= id->death) { 424 TAILQ_REMOVE(&tab->idlist, id, next); 425 free_identity(id); 426 tab->nentries--; 427 } 428 } 429 } 430 } 431 432 static void 433 process_add_identity(SocketEntry *e, int version) 434 { 435 Idtab *tab = idtab_lookup(version); 436 int type, success = 0, death = 0, confirm = 0; 437 char *type_name, *comment; 438 Key *k = NULL; 439 440 switch (version) { 441 case 1: 442 k = key_new_private(KEY_RSA1); 443 (void) buffer_get_int(&e->request); /* ignored */ 444 buffer_get_bignum(&e->request, k->rsa->n); 445 buffer_get_bignum(&e->request, k->rsa->e); 446 buffer_get_bignum(&e->request, k->rsa->d); 447 buffer_get_bignum(&e->request, k->rsa->iqmp); 448 449 /* SSH and SSL have p and q swapped */ 450 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 451 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 452 453 /* Generate additional parameters */ 454 rsa_generate_additional_parameters(k->rsa); 455 break; 456 case 2: 457 type_name = buffer_get_string(&e->request, NULL); 458 type = key_type_from_name(type_name); 459 xfree(type_name); 460 switch (type) { 461 case KEY_DSA: 462 k = key_new_private(type); 463 buffer_get_bignum2(&e->request, k->dsa->p); 464 buffer_get_bignum2(&e->request, k->dsa->q); 465 buffer_get_bignum2(&e->request, k->dsa->g); 466 buffer_get_bignum2(&e->request, k->dsa->pub_key); 467 buffer_get_bignum2(&e->request, k->dsa->priv_key); 468 break; 469 case KEY_RSA: 470 k = key_new_private(type); 471 buffer_get_bignum2(&e->request, k->rsa->n); 472 buffer_get_bignum2(&e->request, k->rsa->e); 473 buffer_get_bignum2(&e->request, k->rsa->d); 474 buffer_get_bignum2(&e->request, k->rsa->iqmp); 475 buffer_get_bignum2(&e->request, k->rsa->p); 476 buffer_get_bignum2(&e->request, k->rsa->q); 477 478 /* Generate additional parameters */ 479 rsa_generate_additional_parameters(k->rsa); 480 break; 481 default: 482 buffer_clear(&e->request); 483 goto send; 484 } 485 break; 486 } 487 /* enable blinding */ 488 switch (k->type) { 489 case KEY_RSA: 490 case KEY_RSA1: 491 if (RSA_blinding_on(k->rsa, NULL) != 1) { 492 error("process_add_identity: RSA_blinding_on failed"); 493 key_free(k); 494 goto send; 495 } 496 break; 497 } 498 comment = buffer_get_string(&e->request, NULL); 499 if (k == NULL) { 500 xfree(comment); 501 goto send; 502 } 503 success = 1; 504 while (buffer_len(&e->request)) { 505 switch (buffer_get_char(&e->request)) { 506 case SSH_AGENT_CONSTRAIN_LIFETIME: 507 death = time(NULL) + buffer_get_int(&e->request); 508 break; 509 case SSH_AGENT_CONSTRAIN_CONFIRM: 510 confirm = 1; 511 break; 512 default: 513 break; 514 } 515 } 516 if (lifetime && !death) 517 death = time(NULL) + lifetime; 518 if (lookup_identity(k, version) == NULL) { 519 Identity *id = xmalloc(sizeof(Identity)); 520 id->key = k; 521 id->comment = comment; 522 id->death = death; 523 id->confirm = confirm; 524 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 525 /* Increment the number of identities. */ 526 tab->nentries++; 527 } else { 528 key_free(k); 529 xfree(comment); 530 } 531 send: 532 buffer_put_int(&e->output, 1); 533 buffer_put_char(&e->output, 534 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 535 } 536 537 /* XXX todo: encrypt sensitive data with passphrase */ 538 static void 539 process_lock_agent(SocketEntry *e, int lock) 540 { 541 int success = 0; 542 char *passwd; 543 544 passwd = buffer_get_string(&e->request, NULL); 545 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 546 locked = 0; 547 memset(lock_passwd, 0, strlen(lock_passwd)); 548 xfree(lock_passwd); 549 lock_passwd = NULL; 550 success = 1; 551 } else if (!locked && lock) { 552 locked = 1; 553 lock_passwd = xstrdup(passwd); 554 success = 1; 555 } 556 memset(passwd, 0, strlen(passwd)); 557 xfree(passwd); 558 559 buffer_put_int(&e->output, 1); 560 buffer_put_char(&e->output, 561 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 562 } 563 564 static void 565 no_identities(SocketEntry *e, u_int type) 566 { 567 Buffer msg; 568 569 buffer_init(&msg); 570 buffer_put_char(&msg, 571 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 572 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 573 buffer_put_int(&msg, 0); 574 buffer_put_int(&e->output, buffer_len(&msg)); 575 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 576 buffer_free(&msg); 577 } 578 579 #ifdef SMARTCARD 580 static void 581 process_add_smartcard_key (SocketEntry *e) 582 { 583 char *sc_reader_id = NULL, *pin; 584 int i, version, success = 0, death = 0, confirm = 0; 585 Key **keys, *k; 586 Identity *id; 587 Idtab *tab; 588 589 sc_reader_id = buffer_get_string(&e->request, NULL); 590 pin = buffer_get_string(&e->request, NULL); 591 592 while (buffer_len(&e->request)) { 593 switch (buffer_get_char(&e->request)) { 594 case SSH_AGENT_CONSTRAIN_LIFETIME: 595 death = time(NULL) + buffer_get_int(&e->request); 596 break; 597 case SSH_AGENT_CONSTRAIN_CONFIRM: 598 confirm = 1; 599 break; 600 default: 601 break; 602 } 603 } 604 if (lifetime && !death) 605 death = time(NULL) + lifetime; 606 607 keys = sc_get_keys(sc_reader_id, pin); 608 xfree(sc_reader_id); 609 xfree(pin); 610 611 if (keys == NULL || keys[0] == NULL) { 612 error("sc_get_keys failed"); 613 goto send; 614 } 615 for (i = 0; keys[i] != NULL; i++) { 616 k = keys[i]; 617 version = k->type == KEY_RSA1 ? 1 : 2; 618 tab = idtab_lookup(version); 619 if (lookup_identity(k, version) == NULL) { 620 id = xmalloc(sizeof(Identity)); 621 id->key = k; 622 id->comment = sc_get_key_label(k); 623 id->death = death; 624 id->confirm = confirm; 625 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 626 tab->nentries++; 627 success = 1; 628 } else { 629 key_free(k); 630 } 631 keys[i] = NULL; 632 } 633 xfree(keys); 634 send: 635 buffer_put_int(&e->output, 1); 636 buffer_put_char(&e->output, 637 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 638 } 639 640 static void 641 process_remove_smartcard_key(SocketEntry *e) 642 { 643 char *sc_reader_id = NULL, *pin; 644 int i, version, success = 0; 645 Key **keys, *k = NULL; 646 Identity *id; 647 Idtab *tab; 648 649 sc_reader_id = buffer_get_string(&e->request, NULL); 650 pin = buffer_get_string(&e->request, NULL); 651 keys = sc_get_keys(sc_reader_id, pin); 652 xfree(sc_reader_id); 653 xfree(pin); 654 655 if (keys == NULL || keys[0] == NULL) { 656 error("sc_get_keys failed"); 657 goto send; 658 } 659 for (i = 0; keys[i] != NULL; i++) { 660 k = keys[i]; 661 version = k->type == KEY_RSA1 ? 1 : 2; 662 if ((id = lookup_identity(k, version)) != NULL) { 663 tab = idtab_lookup(version); 664 TAILQ_REMOVE(&tab->idlist, id, next); 665 tab->nentries--; 666 free_identity(id); 667 success = 1; 668 } 669 key_free(k); 670 keys[i] = NULL; 671 } 672 xfree(keys); 673 send: 674 buffer_put_int(&e->output, 1); 675 buffer_put_char(&e->output, 676 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 677 } 678 #endif /* SMARTCARD */ 679 680 /* dispatch incoming messages */ 681 682 static void 683 process_message(SocketEntry *e) 684 { 685 u_int msg_len, type; 686 u_char *cp; 687 688 /* kill dead keys */ 689 reaper(); 690 691 if (buffer_len(&e->input) < 5) 692 return; /* Incomplete message. */ 693 cp = buffer_ptr(&e->input); 694 msg_len = get_u32(cp); 695 if (msg_len > 256 * 1024) { 696 close_socket(e); 697 return; 698 } 699 if (buffer_len(&e->input) < msg_len + 4) 700 return; 701 702 /* move the current input to e->request */ 703 buffer_consume(&e->input, 4); 704 buffer_clear(&e->request); 705 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 706 buffer_consume(&e->input, msg_len); 707 type = buffer_get_char(&e->request); 708 709 /* check wheter agent is locked */ 710 if (locked && type != SSH_AGENTC_UNLOCK) { 711 buffer_clear(&e->request); 712 switch (type) { 713 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 714 case SSH2_AGENTC_REQUEST_IDENTITIES: 715 /* send empty lists */ 716 no_identities(e, type); 717 break; 718 default: 719 /* send a fail message for all other request types */ 720 buffer_put_int(&e->output, 1); 721 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 722 } 723 return; 724 } 725 726 debug("type %d", type); 727 switch (type) { 728 case SSH_AGENTC_LOCK: 729 case SSH_AGENTC_UNLOCK: 730 process_lock_agent(e, type == SSH_AGENTC_LOCK); 731 break; 732 /* ssh1 */ 733 case SSH_AGENTC_RSA_CHALLENGE: 734 process_authentication_challenge1(e); 735 break; 736 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 737 process_request_identities(e, 1); 738 break; 739 case SSH_AGENTC_ADD_RSA_IDENTITY: 740 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 741 process_add_identity(e, 1); 742 break; 743 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 744 process_remove_identity(e, 1); 745 break; 746 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 747 process_remove_all_identities(e, 1); 748 break; 749 /* ssh2 */ 750 case SSH2_AGENTC_SIGN_REQUEST: 751 process_sign_request2(e); 752 break; 753 case SSH2_AGENTC_REQUEST_IDENTITIES: 754 process_request_identities(e, 2); 755 break; 756 case SSH2_AGENTC_ADD_IDENTITY: 757 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 758 process_add_identity(e, 2); 759 break; 760 case SSH2_AGENTC_REMOVE_IDENTITY: 761 process_remove_identity(e, 2); 762 break; 763 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 764 process_remove_all_identities(e, 2); 765 break; 766 #ifdef SMARTCARD 767 case SSH_AGENTC_ADD_SMARTCARD_KEY: 768 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 769 process_add_smartcard_key(e); 770 break; 771 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 772 process_remove_smartcard_key(e); 773 break; 774 #endif /* SMARTCARD */ 775 default: 776 /* Unknown message. Respond with failure. */ 777 error("Unknown message %d", type); 778 buffer_clear(&e->request); 779 buffer_put_int(&e->output, 1); 780 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 781 break; 782 } 783 } 784 785 static void 786 new_socket(sock_type type, int fd) 787 { 788 u_int i, old_alloc, new_alloc; 789 790 set_nonblock(fd); 791 792 if (fd > max_fd) 793 max_fd = fd; 794 795 for (i = 0; i < sockets_alloc; i++) 796 if (sockets[i].type == AUTH_UNUSED) { 797 sockets[i].fd = fd; 798 buffer_init(&sockets[i].input); 799 buffer_init(&sockets[i].output); 800 buffer_init(&sockets[i].request); 801 sockets[i].type = type; 802 return; 803 } 804 old_alloc = sockets_alloc; 805 new_alloc = sockets_alloc + 10; 806 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0])); 807 for (i = old_alloc; i < new_alloc; i++) 808 sockets[i].type = AUTH_UNUSED; 809 sockets_alloc = new_alloc; 810 sockets[old_alloc].fd = fd; 811 buffer_init(&sockets[old_alloc].input); 812 buffer_init(&sockets[old_alloc].output); 813 buffer_init(&sockets[old_alloc].request); 814 sockets[old_alloc].type = type; 815 } 816 817 static int 818 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp) 819 { 820 u_int i, sz; 821 int n = 0; 822 823 for (i = 0; i < sockets_alloc; i++) { 824 switch (sockets[i].type) { 825 case AUTH_SOCKET: 826 case AUTH_CONNECTION: 827 n = MAX(n, sockets[i].fd); 828 break; 829 case AUTH_UNUSED: 830 break; 831 default: 832 fatal("Unknown socket type %d", sockets[i].type); 833 break; 834 } 835 } 836 837 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 838 if (*fdrp == NULL || sz > *nallocp) { 839 if (*fdrp) 840 xfree(*fdrp); 841 if (*fdwp) 842 xfree(*fdwp); 843 *fdrp = xmalloc(sz); 844 *fdwp = xmalloc(sz); 845 *nallocp = sz; 846 } 847 if (n < *fdl) 848 debug("XXX shrink: %d < %d", n, *fdl); 849 *fdl = n; 850 memset(*fdrp, 0, sz); 851 memset(*fdwp, 0, sz); 852 853 for (i = 0; i < sockets_alloc; i++) { 854 switch (sockets[i].type) { 855 case AUTH_SOCKET: 856 case AUTH_CONNECTION: 857 FD_SET(sockets[i].fd, *fdrp); 858 if (buffer_len(&sockets[i].output) > 0) 859 FD_SET(sockets[i].fd, *fdwp); 860 break; 861 default: 862 break; 863 } 864 } 865 return (1); 866 } 867 868 static void 869 after_select(fd_set *readset, fd_set *writeset) 870 { 871 struct sockaddr_un sunaddr; 872 socklen_t slen; 873 char buf[1024]; 874 int len, sock; 875 u_int i; 876 uid_t euid; 877 gid_t egid; 878 879 for (i = 0; i < sockets_alloc; i++) 880 switch (sockets[i].type) { 881 case AUTH_UNUSED: 882 break; 883 case AUTH_SOCKET: 884 if (FD_ISSET(sockets[i].fd, readset)) { 885 slen = sizeof(sunaddr); 886 sock = accept(sockets[i].fd, 887 (struct sockaddr *)&sunaddr, &slen); 888 if (sock < 0) { 889 error("accept from AUTH_SOCKET: %s", 890 strerror(errno)); 891 break; 892 } 893 if (getpeereid(sock, &euid, &egid) < 0) { 894 error("getpeereid %d failed: %s", 895 sock, strerror(errno)); 896 close(sock); 897 break; 898 } 899 if ((euid != 0) && (getuid() != euid)) { 900 error("uid mismatch: " 901 "peer euid %u != uid %u", 902 (u_int) euid, (u_int) getuid()); 903 close(sock); 904 break; 905 } 906 new_socket(AUTH_CONNECTION, sock); 907 } 908 break; 909 case AUTH_CONNECTION: 910 if (buffer_len(&sockets[i].output) > 0 && 911 FD_ISSET(sockets[i].fd, writeset)) { 912 do { 913 len = write(sockets[i].fd, 914 buffer_ptr(&sockets[i].output), 915 buffer_len(&sockets[i].output)); 916 if (len == -1 && (errno == EAGAIN || 917 errno == EINTR)) 918 continue; 919 break; 920 } while (1); 921 if (len <= 0) { 922 close_socket(&sockets[i]); 923 break; 924 } 925 buffer_consume(&sockets[i].output, len); 926 } 927 if (FD_ISSET(sockets[i].fd, readset)) { 928 do { 929 len = read(sockets[i].fd, buf, sizeof(buf)); 930 if (len == -1 && (errno == EAGAIN || 931 errno == EINTR)) 932 continue; 933 break; 934 } while (1); 935 if (len <= 0) { 936 close_socket(&sockets[i]); 937 break; 938 } 939 buffer_append(&sockets[i].input, buf, len); 940 process_message(&sockets[i]); 941 } 942 break; 943 default: 944 fatal("Unknown type %d", sockets[i].type); 945 } 946 } 947 948 static void 949 cleanup_socket(void) 950 { 951 if (socket_name[0]) 952 unlink(socket_name); 953 if (socket_dir[0]) 954 rmdir(socket_dir); 955 } 956 957 void 958 cleanup_exit(int i) 959 { 960 cleanup_socket(); 961 _exit(i); 962 } 963 964 /*ARGSUSED*/ 965 static void 966 cleanup_handler(int sig) 967 { 968 cleanup_socket(); 969 _exit(2); 970 } 971 972 /*ARGSUSED*/ 973 static void 974 check_parent_exists(int sig) 975 { 976 int save_errno = errno; 977 978 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 979 /* printf("Parent has died - Authentication agent exiting.\n"); */ 980 cleanup_handler(sig); /* safe */ 981 } 982 signal(SIGALRM, check_parent_exists); 983 alarm(10); 984 errno = save_errno; 985 } 986 987 static void 988 usage(void) 989 { 990 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n", 991 __progname); 992 fprintf(stderr, "Options:\n"); 993 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 994 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 995 fprintf(stderr, " -k Kill the current agent.\n"); 996 fprintf(stderr, " -d Debug mode.\n"); 997 fprintf(stderr, " -a socket Bind agent socket to given name.\n"); 998 fprintf(stderr, " -t life Default identity lifetime (seconds).\n"); 999 exit(1); 1000 } 1001 1002 int 1003 main(int ac, char **av) 1004 { 1005 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1006 int sock, fd, ch; 1007 u_int nalloc; 1008 char *shell, *format, *pidstr, *agentsocket = NULL; 1009 fd_set *readsetp = NULL, *writesetp = NULL; 1010 struct sockaddr_un sunaddr; 1011 struct rlimit rlim; 1012 extern int optind; 1013 extern char *optarg; 1014 pid_t pid; 1015 char pidstrbuf[1 + 3 * sizeof pid]; 1016 1017 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1018 sanitise_stdfd(); 1019 1020 /* drop */ 1021 setegid(getgid()); 1022 setgid(getgid()); 1023 1024 SSLeay_add_all_algorithms(); 1025 1026 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) { 1027 switch (ch) { 1028 case 'c': 1029 if (s_flag) 1030 usage(); 1031 c_flag++; 1032 break; 1033 case 'k': 1034 k_flag++; 1035 break; 1036 case 's': 1037 if (c_flag) 1038 usage(); 1039 s_flag++; 1040 break; 1041 case 'd': 1042 if (d_flag) 1043 usage(); 1044 d_flag++; 1045 break; 1046 case 'a': 1047 agentsocket = optarg; 1048 break; 1049 case 't': 1050 if ((lifetime = convtime(optarg)) == -1) { 1051 fprintf(stderr, "Invalid lifetime\n"); 1052 usage(); 1053 } 1054 break; 1055 default: 1056 usage(); 1057 } 1058 } 1059 ac -= optind; 1060 av += optind; 1061 1062 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1063 usage(); 1064 1065 if (ac == 0 && !c_flag && !s_flag) { 1066 shell = getenv("SHELL"); 1067 if (shell != NULL && 1068 strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 1069 c_flag = 1; 1070 } 1071 if (k_flag) { 1072 const char *errstr = NULL; 1073 1074 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1075 if (pidstr == NULL) { 1076 fprintf(stderr, "%s not set, cannot kill agent\n", 1077 SSH_AGENTPID_ENV_NAME); 1078 exit(1); 1079 } 1080 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1081 if (errstr) { 1082 fprintf(stderr, 1083 "%s=\"%s\", which is not a good PID: %s\n", 1084 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1085 exit(1); 1086 } 1087 if (kill(pid, SIGTERM) == -1) { 1088 perror("kill"); 1089 exit(1); 1090 } 1091 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1092 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1093 printf(format, SSH_AGENTPID_ENV_NAME); 1094 printf("echo Agent pid %ld killed;\n", (long)pid); 1095 exit(0); 1096 } 1097 parent_pid = getpid(); 1098 1099 if (agentsocket == NULL) { 1100 /* Create private directory for agent socket */ 1101 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir); 1102 if (mkdtemp(socket_dir) == NULL) { 1103 perror("mkdtemp: private socket dir"); 1104 exit(1); 1105 } 1106 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1107 (long)parent_pid); 1108 } else { 1109 /* Try to use specified agent socket */ 1110 socket_dir[0] = '\0'; 1111 strlcpy(socket_name, agentsocket, sizeof socket_name); 1112 } 1113 1114 /* 1115 * Create socket early so it will exist before command gets run from 1116 * the parent. 1117 */ 1118 sock = socket(AF_UNIX, SOCK_STREAM, 0); 1119 if (sock < 0) { 1120 perror("socket"); 1121 *socket_name = '\0'; /* Don't unlink any existing file */ 1122 cleanup_exit(1); 1123 } 1124 memset(&sunaddr, 0, sizeof(sunaddr)); 1125 sunaddr.sun_family = AF_UNIX; 1126 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 1127 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 1128 perror("bind"); 1129 *socket_name = '\0'; /* Don't unlink any existing file */ 1130 cleanup_exit(1); 1131 } 1132 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 1133 perror("listen"); 1134 cleanup_exit(1); 1135 } 1136 1137 /* 1138 * Fork, and have the parent execute the command, if any, or present 1139 * the socket data. The child continues as the authentication agent. 1140 */ 1141 if (d_flag) { 1142 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1143 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1144 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1145 SSH_AUTHSOCKET_ENV_NAME); 1146 printf("echo Agent pid %ld;\n", (long)parent_pid); 1147 goto skip; 1148 } 1149 pid = fork(); 1150 if (pid == -1) { 1151 perror("fork"); 1152 cleanup_exit(1); 1153 } 1154 if (pid != 0) { /* Parent - execute the given command. */ 1155 close(sock); 1156 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1157 if (ac == 0) { 1158 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1159 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1160 SSH_AUTHSOCKET_ENV_NAME); 1161 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1162 SSH_AGENTPID_ENV_NAME); 1163 printf("echo Agent pid %ld;\n", (long)pid); 1164 exit(0); 1165 } 1166 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1167 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1168 perror("setenv"); 1169 exit(1); 1170 } 1171 execvp(av[0], av); 1172 perror(av[0]); 1173 exit(1); 1174 } 1175 /* child */ 1176 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1177 1178 if (setsid() == -1) { 1179 error("setsid: %s", strerror(errno)); 1180 cleanup_exit(1); 1181 } 1182 1183 (void)chdir("/"); 1184 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1185 /* XXX might close listen socket */ 1186 (void)dup2(fd, STDIN_FILENO); 1187 (void)dup2(fd, STDOUT_FILENO); 1188 (void)dup2(fd, STDERR_FILENO); 1189 if (fd > 2) 1190 close(fd); 1191 } 1192 1193 /* deny core dumps, since memory contains unencrypted private keys */ 1194 rlim.rlim_cur = rlim.rlim_max = 0; 1195 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1196 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1197 cleanup_exit(1); 1198 } 1199 1200 skip: 1201 new_socket(AUTH_SOCKET, sock); 1202 if (ac > 0) { 1203 signal(SIGALRM, check_parent_exists); 1204 alarm(10); 1205 } 1206 idtab_init(); 1207 if (!d_flag) 1208 signal(SIGINT, SIG_IGN); 1209 signal(SIGPIPE, SIG_IGN); 1210 signal(SIGHUP, cleanup_handler); 1211 signal(SIGTERM, cleanup_handler); 1212 nalloc = 0; 1213 1214 while (1) { 1215 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc); 1216 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) { 1217 if (errno == EINTR) 1218 continue; 1219 fatal("select: %s", strerror(errno)); 1220 } 1221 after_select(readsetp, writesetp); 1222 } 1223 /* NOTREACHED */ 1224 } 1225