1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * The authentication agent program. 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 #include <sys/queue.h> 38 RCSID("$OpenBSD: ssh-agent.c,v 1.105 2002/10/01 20:34:12 markus Exp $"); 39 40 #include <openssl/evp.h> 41 #include <openssl/md5.h> 42 43 #include "ssh.h" 44 #include "rsa.h" 45 #include "buffer.h" 46 #include "bufaux.h" 47 #include "xmalloc.h" 48 #include "getput.h" 49 #include "key.h" 50 #include "authfd.h" 51 #include "compat.h" 52 #include "log.h" 53 54 #ifdef SMARTCARD 55 #include "scard.h" 56 #endif 57 58 typedef enum { 59 AUTH_UNUSED, 60 AUTH_SOCKET, 61 AUTH_CONNECTION 62 } sock_type; 63 64 typedef struct { 65 int fd; 66 sock_type type; 67 Buffer input; 68 Buffer output; 69 Buffer request; 70 } SocketEntry; 71 72 u_int sockets_alloc = 0; 73 SocketEntry *sockets = NULL; 74 75 typedef struct identity { 76 TAILQ_ENTRY(identity) next; 77 Key *key; 78 char *comment; 79 u_int death; 80 } Identity; 81 82 typedef struct { 83 int nentries; 84 TAILQ_HEAD(idqueue, identity) idlist; 85 } Idtab; 86 87 /* private key table, one per protocol version */ 88 Idtab idtable[3]; 89 90 int max_fd = 0; 91 92 /* pid of shell == parent of agent */ 93 pid_t parent_pid = -1; 94 95 /* pathname and directory for AUTH_SOCKET */ 96 char socket_name[1024]; 97 char socket_dir[1024]; 98 99 /* locking */ 100 int locked = 0; 101 char *lock_passwd = NULL; 102 103 extern char *__progname; 104 105 static void 106 close_socket(SocketEntry *e) 107 { 108 close(e->fd); 109 e->fd = -1; 110 e->type = AUTH_UNUSED; 111 buffer_free(&e->input); 112 buffer_free(&e->output); 113 buffer_free(&e->request); 114 } 115 116 static void 117 idtab_init(void) 118 { 119 int i; 120 121 for (i = 0; i <=2; i++) { 122 TAILQ_INIT(&idtable[i].idlist); 123 idtable[i].nentries = 0; 124 } 125 } 126 127 /* return private key table for requested protocol version */ 128 static Idtab * 129 idtab_lookup(int version) 130 { 131 if (version < 1 || version > 2) 132 fatal("internal error, bad protocol version %d", version); 133 return &idtable[version]; 134 } 135 136 static void 137 free_identity(Identity *id) 138 { 139 key_free(id->key); 140 xfree(id->comment); 141 xfree(id); 142 } 143 144 /* return matching private key for given public key */ 145 static Identity * 146 lookup_identity(Key *key, int version) 147 { 148 Identity *id; 149 150 Idtab *tab = idtab_lookup(version); 151 TAILQ_FOREACH(id, &tab->idlist, next) { 152 if (key_equal(key, id->key)) 153 return (id); 154 } 155 return (NULL); 156 } 157 158 /* send list of supported public keys to 'client' */ 159 static void 160 process_request_identities(SocketEntry *e, int version) 161 { 162 Idtab *tab = idtab_lookup(version); 163 Identity *id; 164 Buffer msg; 165 166 buffer_init(&msg); 167 buffer_put_char(&msg, (version == 1) ? 168 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 169 buffer_put_int(&msg, tab->nentries); 170 TAILQ_FOREACH(id, &tab->idlist, next) { 171 if (id->key->type == KEY_RSA1) { 172 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 173 buffer_put_bignum(&msg, id->key->rsa->e); 174 buffer_put_bignum(&msg, id->key->rsa->n); 175 } else { 176 u_char *blob; 177 u_int blen; 178 key_to_blob(id->key, &blob, &blen); 179 buffer_put_string(&msg, blob, blen); 180 xfree(blob); 181 } 182 buffer_put_cstring(&msg, id->comment); 183 } 184 buffer_put_int(&e->output, buffer_len(&msg)); 185 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 186 buffer_free(&msg); 187 } 188 189 /* ssh1 only */ 190 static void 191 process_authentication_challenge1(SocketEntry *e) 192 { 193 u_char buf[32], mdbuf[16], session_id[16]; 194 u_int response_type; 195 BIGNUM *challenge; 196 Identity *id; 197 int i, len; 198 Buffer msg; 199 MD5_CTX md; 200 Key *key; 201 202 buffer_init(&msg); 203 key = key_new(KEY_RSA1); 204 if ((challenge = BN_new()) == NULL) 205 fatal("process_authentication_challenge1: BN_new failed"); 206 207 (void) buffer_get_int(&e->request); /* ignored */ 208 buffer_get_bignum(&e->request, key->rsa->e); 209 buffer_get_bignum(&e->request, key->rsa->n); 210 buffer_get_bignum(&e->request, challenge); 211 212 /* Only protocol 1.1 is supported */ 213 if (buffer_len(&e->request) == 0) 214 goto failure; 215 buffer_get(&e->request, session_id, 16); 216 response_type = buffer_get_int(&e->request); 217 if (response_type != 1) 218 goto failure; 219 220 id = lookup_identity(key, 1); 221 if (id != NULL) { 222 Key *private = id->key; 223 /* Decrypt the challenge using the private key. */ 224 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 225 goto failure; 226 227 /* The response is MD5 of decrypted challenge plus session id. */ 228 len = BN_num_bytes(challenge); 229 if (len <= 0 || len > 32) { 230 log("process_authentication_challenge: bad challenge length %d", len); 231 goto failure; 232 } 233 memset(buf, 0, 32); 234 BN_bn2bin(challenge, buf + 32 - len); 235 MD5_Init(&md); 236 MD5_Update(&md, buf, 32); 237 MD5_Update(&md, session_id, 16); 238 MD5_Final(mdbuf, &md); 239 240 /* Send the response. */ 241 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 242 for (i = 0; i < 16; i++) 243 buffer_put_char(&msg, mdbuf[i]); 244 goto send; 245 } 246 247 failure: 248 /* Unknown identity or protocol error. Send failure. */ 249 buffer_put_char(&msg, SSH_AGENT_FAILURE); 250 send: 251 buffer_put_int(&e->output, buffer_len(&msg)); 252 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 253 key_free(key); 254 BN_clear_free(challenge); 255 buffer_free(&msg); 256 } 257 258 /* ssh2 only */ 259 static void 260 process_sign_request2(SocketEntry *e) 261 { 262 u_char *blob, *data, *signature = NULL; 263 u_int blen, dlen, slen = 0; 264 extern int datafellows; 265 int ok = -1, flags; 266 Buffer msg; 267 Key *key; 268 269 datafellows = 0; 270 271 blob = buffer_get_string(&e->request, &blen); 272 data = buffer_get_string(&e->request, &dlen); 273 274 flags = buffer_get_int(&e->request); 275 if (flags & SSH_AGENT_OLD_SIGNATURE) 276 datafellows = SSH_BUG_SIGBLOB; 277 278 key = key_from_blob(blob, blen); 279 if (key != NULL) { 280 Identity *id = lookup_identity(key, 2); 281 if (id != NULL) 282 ok = key_sign(id->key, &signature, &slen, data, dlen); 283 } 284 key_free(key); 285 buffer_init(&msg); 286 if (ok == 0) { 287 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 288 buffer_put_string(&msg, signature, slen); 289 } else { 290 buffer_put_char(&msg, SSH_AGENT_FAILURE); 291 } 292 buffer_put_int(&e->output, buffer_len(&msg)); 293 buffer_append(&e->output, buffer_ptr(&msg), 294 buffer_len(&msg)); 295 buffer_free(&msg); 296 xfree(data); 297 xfree(blob); 298 if (signature != NULL) 299 xfree(signature); 300 } 301 302 /* shared */ 303 static void 304 process_remove_identity(SocketEntry *e, int version) 305 { 306 u_int blen, bits; 307 int success = 0; 308 Key *key = NULL; 309 u_char *blob; 310 311 switch (version) { 312 case 1: 313 key = key_new(KEY_RSA1); 314 bits = buffer_get_int(&e->request); 315 buffer_get_bignum(&e->request, key->rsa->e); 316 buffer_get_bignum(&e->request, key->rsa->n); 317 318 if (bits != key_size(key)) 319 log("Warning: identity keysize mismatch: actual %u, announced %u", 320 key_size(key), bits); 321 break; 322 case 2: 323 blob = buffer_get_string(&e->request, &blen); 324 key = key_from_blob(blob, blen); 325 xfree(blob); 326 break; 327 } 328 if (key != NULL) { 329 Identity *id = lookup_identity(key, version); 330 if (id != NULL) { 331 /* 332 * We have this key. Free the old key. Since we 333 * don\'t want to leave empty slots in the middle of 334 * the array, we actually free the key there and move 335 * all the entries between the empty slot and the end 336 * of the array. 337 */ 338 Idtab *tab = idtab_lookup(version); 339 if (tab->nentries < 1) 340 fatal("process_remove_identity: " 341 "internal error: tab->nentries %d", 342 tab->nentries); 343 TAILQ_REMOVE(&tab->idlist, id, next); 344 free_identity(id); 345 tab->nentries--; 346 success = 1; 347 } 348 key_free(key); 349 } 350 buffer_put_int(&e->output, 1); 351 buffer_put_char(&e->output, 352 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 353 } 354 355 static void 356 process_remove_all_identities(SocketEntry *e, int version) 357 { 358 Idtab *tab = idtab_lookup(version); 359 Identity *id; 360 361 /* Loop over all identities and clear the keys. */ 362 for (id = TAILQ_FIRST(&tab->idlist); id; 363 id = TAILQ_FIRST(&tab->idlist)) { 364 TAILQ_REMOVE(&tab->idlist, id, next); 365 free_identity(id); 366 } 367 368 /* Mark that there are no identities. */ 369 tab->nentries = 0; 370 371 /* Send success. */ 372 buffer_put_int(&e->output, 1); 373 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 374 } 375 376 static void 377 reaper(void) 378 { 379 u_int now = time(NULL); 380 Identity *id, *nxt; 381 int version; 382 Idtab *tab; 383 384 for (version = 1; version < 3; version++) { 385 tab = idtab_lookup(version); 386 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 387 nxt = TAILQ_NEXT(id, next); 388 if (id->death != 0 && now >= id->death) { 389 TAILQ_REMOVE(&tab->idlist, id, next); 390 free_identity(id); 391 tab->nentries--; 392 } 393 } 394 } 395 } 396 397 static void 398 process_add_identity(SocketEntry *e, int version) 399 { 400 Idtab *tab = idtab_lookup(version); 401 int type, success = 0, death = 0; 402 char *type_name, *comment; 403 Key *k = NULL; 404 405 switch (version) { 406 case 1: 407 k = key_new_private(KEY_RSA1); 408 (void) buffer_get_int(&e->request); /* ignored */ 409 buffer_get_bignum(&e->request, k->rsa->n); 410 buffer_get_bignum(&e->request, k->rsa->e); 411 buffer_get_bignum(&e->request, k->rsa->d); 412 buffer_get_bignum(&e->request, k->rsa->iqmp); 413 414 /* SSH and SSL have p and q swapped */ 415 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 416 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 417 418 /* Generate additional parameters */ 419 rsa_generate_additional_parameters(k->rsa); 420 break; 421 case 2: 422 type_name = buffer_get_string(&e->request, NULL); 423 type = key_type_from_name(type_name); 424 xfree(type_name); 425 switch (type) { 426 case KEY_DSA: 427 k = key_new_private(type); 428 buffer_get_bignum2(&e->request, k->dsa->p); 429 buffer_get_bignum2(&e->request, k->dsa->q); 430 buffer_get_bignum2(&e->request, k->dsa->g); 431 buffer_get_bignum2(&e->request, k->dsa->pub_key); 432 buffer_get_bignum2(&e->request, k->dsa->priv_key); 433 break; 434 case KEY_RSA: 435 k = key_new_private(type); 436 buffer_get_bignum2(&e->request, k->rsa->n); 437 buffer_get_bignum2(&e->request, k->rsa->e); 438 buffer_get_bignum2(&e->request, k->rsa->d); 439 buffer_get_bignum2(&e->request, k->rsa->iqmp); 440 buffer_get_bignum2(&e->request, k->rsa->p); 441 buffer_get_bignum2(&e->request, k->rsa->q); 442 443 /* Generate additional parameters */ 444 rsa_generate_additional_parameters(k->rsa); 445 break; 446 default: 447 buffer_clear(&e->request); 448 goto send; 449 } 450 break; 451 } 452 comment = buffer_get_string(&e->request, NULL); 453 if (k == NULL) { 454 xfree(comment); 455 goto send; 456 } 457 success = 1; 458 while (buffer_len(&e->request)) { 459 switch (buffer_get_char(&e->request)) { 460 case SSH_AGENT_CONSTRAIN_LIFETIME: 461 death = time(NULL) + buffer_get_int(&e->request); 462 break; 463 default: 464 break; 465 } 466 } 467 if (lookup_identity(k, version) == NULL) { 468 Identity *id = xmalloc(sizeof(Identity)); 469 id->key = k; 470 id->comment = comment; 471 id->death = death; 472 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 473 /* Increment the number of identities. */ 474 tab->nentries++; 475 } else { 476 key_free(k); 477 xfree(comment); 478 } 479 send: 480 buffer_put_int(&e->output, 1); 481 buffer_put_char(&e->output, 482 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 483 } 484 485 /* XXX todo: encrypt sensitive data with passphrase */ 486 static void 487 process_lock_agent(SocketEntry *e, int lock) 488 { 489 int success = 0; 490 char *passwd; 491 492 passwd = buffer_get_string(&e->request, NULL); 493 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 494 locked = 0; 495 memset(lock_passwd, 0, strlen(lock_passwd)); 496 xfree(lock_passwd); 497 lock_passwd = NULL; 498 success = 1; 499 } else if (!locked && lock) { 500 locked = 1; 501 lock_passwd = xstrdup(passwd); 502 success = 1; 503 } 504 memset(passwd, 0, strlen(passwd)); 505 xfree(passwd); 506 507 buffer_put_int(&e->output, 1); 508 buffer_put_char(&e->output, 509 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 510 } 511 512 static void 513 no_identities(SocketEntry *e, u_int type) 514 { 515 Buffer msg; 516 517 buffer_init(&msg); 518 buffer_put_char(&msg, 519 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 520 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 521 buffer_put_int(&msg, 0); 522 buffer_put_int(&e->output, buffer_len(&msg)); 523 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 524 buffer_free(&msg); 525 } 526 527 #ifdef SMARTCARD 528 static void 529 process_add_smartcard_key (SocketEntry *e) 530 { 531 char *sc_reader_id = NULL, *pin; 532 int i, version, success = 0; 533 Key **keys, *k; 534 Identity *id; 535 Idtab *tab; 536 537 sc_reader_id = buffer_get_string(&e->request, NULL); 538 pin = buffer_get_string(&e->request, NULL); 539 keys = sc_get_keys(sc_reader_id, pin); 540 xfree(sc_reader_id); 541 xfree(pin); 542 543 if (keys == NULL || keys[0] == NULL) { 544 error("sc_get_keys failed"); 545 goto send; 546 } 547 for (i = 0; keys[i] != NULL; i++) { 548 k = keys[i]; 549 version = k->type == KEY_RSA1 ? 1 : 2; 550 tab = idtab_lookup(version); 551 if (lookup_identity(k, version) == NULL) { 552 id = xmalloc(sizeof(Identity)); 553 id->key = k; 554 id->comment = xstrdup("smartcard key"); 555 id->death = 0; 556 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 557 tab->nentries++; 558 success = 1; 559 } else { 560 key_free(k); 561 } 562 keys[i] = NULL; 563 } 564 xfree(keys); 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 static void 572 process_remove_smartcard_key(SocketEntry *e) 573 { 574 char *sc_reader_id = NULL, *pin; 575 int i, version, success = 0; 576 Key **keys, *k = NULL; 577 Identity *id; 578 Idtab *tab; 579 580 sc_reader_id = buffer_get_string(&e->request, NULL); 581 pin = buffer_get_string(&e->request, NULL); 582 keys = sc_get_keys(sc_reader_id, pin); 583 xfree(sc_reader_id); 584 xfree(pin); 585 586 if (keys == NULL || keys[0] == NULL) { 587 error("sc_get_keys failed"); 588 goto send; 589 } 590 for (i = 0; keys[i] != NULL; i++) { 591 k = keys[i]; 592 version = k->type == KEY_RSA1 ? 1 : 2; 593 if ((id = lookup_identity(k, version)) != NULL) { 594 tab = idtab_lookup(version); 595 TAILQ_REMOVE(&tab->idlist, id, next); 596 tab->nentries--; 597 free_identity(id); 598 success = 1; 599 } 600 key_free(k); 601 keys[i] = NULL; 602 } 603 xfree(keys); 604 send: 605 buffer_put_int(&e->output, 1); 606 buffer_put_char(&e->output, 607 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 608 } 609 #endif /* SMARTCARD */ 610 611 /* dispatch incoming messages */ 612 613 static void 614 process_message(SocketEntry *e) 615 { 616 u_int msg_len, type; 617 u_char *cp; 618 619 /* kill dead keys */ 620 reaper(); 621 622 if (buffer_len(&e->input) < 5) 623 return; /* Incomplete message. */ 624 cp = buffer_ptr(&e->input); 625 msg_len = GET_32BIT(cp); 626 if (msg_len > 256 * 1024) { 627 close_socket(e); 628 return; 629 } 630 if (buffer_len(&e->input) < msg_len + 4) 631 return; 632 633 /* move the current input to e->request */ 634 buffer_consume(&e->input, 4); 635 buffer_clear(&e->request); 636 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 637 buffer_consume(&e->input, msg_len); 638 type = buffer_get_char(&e->request); 639 640 /* check wheter agent is locked */ 641 if (locked && type != SSH_AGENTC_UNLOCK) { 642 buffer_clear(&e->request); 643 switch (type) { 644 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 645 case SSH2_AGENTC_REQUEST_IDENTITIES: 646 /* send empty lists */ 647 no_identities(e, type); 648 break; 649 default: 650 /* send a fail message for all other request types */ 651 buffer_put_int(&e->output, 1); 652 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 653 } 654 return; 655 } 656 657 debug("type %d", type); 658 switch (type) { 659 case SSH_AGENTC_LOCK: 660 case SSH_AGENTC_UNLOCK: 661 process_lock_agent(e, type == SSH_AGENTC_LOCK); 662 break; 663 /* ssh1 */ 664 case SSH_AGENTC_RSA_CHALLENGE: 665 process_authentication_challenge1(e); 666 break; 667 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 668 process_request_identities(e, 1); 669 break; 670 case SSH_AGENTC_ADD_RSA_IDENTITY: 671 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 672 process_add_identity(e, 1); 673 break; 674 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 675 process_remove_identity(e, 1); 676 break; 677 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 678 process_remove_all_identities(e, 1); 679 break; 680 /* ssh2 */ 681 case SSH2_AGENTC_SIGN_REQUEST: 682 process_sign_request2(e); 683 break; 684 case SSH2_AGENTC_REQUEST_IDENTITIES: 685 process_request_identities(e, 2); 686 break; 687 case SSH2_AGENTC_ADD_IDENTITY: 688 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 689 process_add_identity(e, 2); 690 break; 691 case SSH2_AGENTC_REMOVE_IDENTITY: 692 process_remove_identity(e, 2); 693 break; 694 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 695 process_remove_all_identities(e, 2); 696 break; 697 #ifdef SMARTCARD 698 case SSH_AGENTC_ADD_SMARTCARD_KEY: 699 process_add_smartcard_key(e); 700 break; 701 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 702 process_remove_smartcard_key(e); 703 break; 704 #endif /* SMARTCARD */ 705 default: 706 /* Unknown message. Respond with failure. */ 707 error("Unknown message %d", type); 708 buffer_clear(&e->request); 709 buffer_put_int(&e->output, 1); 710 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 711 break; 712 } 713 } 714 715 static void 716 new_socket(sock_type type, int fd) 717 { 718 u_int i, old_alloc; 719 720 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) 721 error("fcntl O_NONBLOCK: %s", strerror(errno)); 722 723 if (fd > max_fd) 724 max_fd = fd; 725 726 for (i = 0; i < sockets_alloc; i++) 727 if (sockets[i].type == AUTH_UNUSED) { 728 sockets[i].fd = fd; 729 sockets[i].type = type; 730 buffer_init(&sockets[i].input); 731 buffer_init(&sockets[i].output); 732 buffer_init(&sockets[i].request); 733 return; 734 } 735 old_alloc = sockets_alloc; 736 sockets_alloc += 10; 737 if (sockets) 738 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); 739 else 740 sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); 741 for (i = old_alloc; i < sockets_alloc; i++) 742 sockets[i].type = AUTH_UNUSED; 743 sockets[old_alloc].type = type; 744 sockets[old_alloc].fd = fd; 745 buffer_init(&sockets[old_alloc].input); 746 buffer_init(&sockets[old_alloc].output); 747 buffer_init(&sockets[old_alloc].request); 748 } 749 750 static int 751 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp) 752 { 753 u_int i, sz; 754 int n = 0; 755 756 for (i = 0; i < sockets_alloc; i++) { 757 switch (sockets[i].type) { 758 case AUTH_SOCKET: 759 case AUTH_CONNECTION: 760 n = MAX(n, sockets[i].fd); 761 break; 762 case AUTH_UNUSED: 763 break; 764 default: 765 fatal("Unknown socket type %d", sockets[i].type); 766 break; 767 } 768 } 769 770 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 771 if (*fdrp == NULL || sz > *nallocp) { 772 if (*fdrp) 773 xfree(*fdrp); 774 if (*fdwp) 775 xfree(*fdwp); 776 *fdrp = xmalloc(sz); 777 *fdwp = xmalloc(sz); 778 *nallocp = sz; 779 } 780 if (n < *fdl) 781 debug("XXX shrink: %d < %d", n, *fdl); 782 *fdl = n; 783 memset(*fdrp, 0, sz); 784 memset(*fdwp, 0, sz); 785 786 for (i = 0; i < sockets_alloc; i++) { 787 switch (sockets[i].type) { 788 case AUTH_SOCKET: 789 case AUTH_CONNECTION: 790 FD_SET(sockets[i].fd, *fdrp); 791 if (buffer_len(&sockets[i].output) > 0) 792 FD_SET(sockets[i].fd, *fdwp); 793 break; 794 default: 795 break; 796 } 797 } 798 return (1); 799 } 800 801 static void 802 after_select(fd_set *readset, fd_set *writeset) 803 { 804 struct sockaddr_un sunaddr; 805 socklen_t slen; 806 char buf[1024]; 807 int len, sock; 808 u_int i; 809 uid_t euid; 810 gid_t egid; 811 812 for (i = 0; i < sockets_alloc; i++) 813 switch (sockets[i].type) { 814 case AUTH_UNUSED: 815 break; 816 case AUTH_SOCKET: 817 if (FD_ISSET(sockets[i].fd, readset)) { 818 slen = sizeof(sunaddr); 819 sock = accept(sockets[i].fd, 820 (struct sockaddr *) &sunaddr, &slen); 821 if (sock < 0) { 822 error("accept from AUTH_SOCKET: %s", 823 strerror(errno)); 824 break; 825 } 826 if (getpeereid(sock, &euid, &egid) < 0) { 827 error("getpeereid %d failed: %s", 828 sock, strerror(errno)); 829 close(sock); 830 break; 831 } 832 if ((euid != 0) && (getuid() != euid)) { 833 error("uid mismatch: " 834 "peer euid %u != uid %u", 835 (u_int) euid, (u_int) getuid()); 836 close(sock); 837 break; 838 } 839 new_socket(AUTH_CONNECTION, sock); 840 } 841 break; 842 case AUTH_CONNECTION: 843 if (buffer_len(&sockets[i].output) > 0 && 844 FD_ISSET(sockets[i].fd, writeset)) { 845 do { 846 len = write(sockets[i].fd, 847 buffer_ptr(&sockets[i].output), 848 buffer_len(&sockets[i].output)); 849 if (len == -1 && (errno == EAGAIN || 850 errno == EINTR)) 851 continue; 852 break; 853 } while (1); 854 if (len <= 0) { 855 close_socket(&sockets[i]); 856 break; 857 } 858 buffer_consume(&sockets[i].output, len); 859 } 860 if (FD_ISSET(sockets[i].fd, readset)) { 861 do { 862 len = read(sockets[i].fd, buf, sizeof(buf)); 863 if (len == -1 && (errno == EAGAIN || 864 errno == EINTR)) 865 continue; 866 break; 867 } while (1); 868 if (len <= 0) { 869 close_socket(&sockets[i]); 870 break; 871 } 872 buffer_append(&sockets[i].input, buf, len); 873 process_message(&sockets[i]); 874 } 875 break; 876 default: 877 fatal("Unknown type %d", sockets[i].type); 878 } 879 } 880 881 static void 882 cleanup_socket(void *p) 883 { 884 if (socket_name[0]) 885 unlink(socket_name); 886 if (socket_dir[0]) 887 rmdir(socket_dir); 888 } 889 890 static void 891 cleanup_exit(int i) 892 { 893 cleanup_socket(NULL); 894 exit(i); 895 } 896 897 static void 898 cleanup_handler(int sig) 899 { 900 cleanup_socket(NULL); 901 _exit(2); 902 } 903 904 static void 905 check_parent_exists(int sig) 906 { 907 int save_errno = errno; 908 909 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 910 /* printf("Parent has died - Authentication agent exiting.\n"); */ 911 cleanup_handler(sig); /* safe */ 912 } 913 signal(SIGALRM, check_parent_exists); 914 alarm(10); 915 errno = save_errno; 916 } 917 918 static void 919 usage(void) 920 { 921 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n", 922 __progname); 923 fprintf(stderr, "Options:\n"); 924 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 925 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 926 fprintf(stderr, " -k Kill the current agent.\n"); 927 fprintf(stderr, " -d Debug mode.\n"); 928 fprintf(stderr, " -a socket Bind agent socket to given name.\n"); 929 exit(1); 930 } 931 932 int 933 main(int ac, char **av) 934 { 935 int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc; 936 char *shell, *format, *pidstr, *agentsocket = NULL; 937 fd_set *readsetp = NULL, *writesetp = NULL; 938 struct sockaddr_un sunaddr; 939 struct rlimit rlim; 940 extern int optind; 941 extern char *optarg; 942 pid_t pid; 943 char pidstrbuf[1 + 3 * sizeof pid]; 944 945 /* drop */ 946 setegid(getgid()); 947 setgid(getgid()); 948 949 SSLeay_add_all_algorithms(); 950 951 while ((ch = getopt(ac, av, "cdksa:")) != -1) { 952 switch (ch) { 953 case 'c': 954 if (s_flag) 955 usage(); 956 c_flag++; 957 break; 958 case 'k': 959 k_flag++; 960 break; 961 case 's': 962 if (c_flag) 963 usage(); 964 s_flag++; 965 break; 966 case 'd': 967 if (d_flag) 968 usage(); 969 d_flag++; 970 break; 971 case 'a': 972 agentsocket = optarg; 973 break; 974 default: 975 usage(); 976 } 977 } 978 ac -= optind; 979 av += optind; 980 981 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 982 usage(); 983 984 if (ac == 0 && !c_flag && !s_flag) { 985 shell = getenv("SHELL"); 986 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 987 c_flag = 1; 988 } 989 if (k_flag) { 990 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 991 if (pidstr == NULL) { 992 fprintf(stderr, "%s not set, cannot kill agent\n", 993 SSH_AGENTPID_ENV_NAME); 994 exit(1); 995 } 996 pid = atoi(pidstr); 997 if (pid < 1) { 998 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 999 SSH_AGENTPID_ENV_NAME, pidstr); 1000 exit(1); 1001 } 1002 if (kill(pid, SIGTERM) == -1) { 1003 perror("kill"); 1004 exit(1); 1005 } 1006 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1007 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1008 printf(format, SSH_AGENTPID_ENV_NAME); 1009 printf("echo Agent pid %ld killed;\n", (long)pid); 1010 exit(0); 1011 } 1012 parent_pid = getpid(); 1013 1014 if (agentsocket == NULL) { 1015 /* Create private directory for agent socket */ 1016 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); 1017 if (mkdtemp(socket_dir) == NULL) { 1018 perror("mkdtemp: private socket dir"); 1019 exit(1); 1020 } 1021 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1022 (long)parent_pid); 1023 } else { 1024 /* Try to use specified agent socket */ 1025 socket_dir[0] = '\0'; 1026 strlcpy(socket_name, agentsocket, sizeof socket_name); 1027 } 1028 1029 /* 1030 * Create socket early so it will exist before command gets run from 1031 * the parent. 1032 */ 1033 sock = socket(AF_UNIX, SOCK_STREAM, 0); 1034 if (sock < 0) { 1035 perror("socket"); 1036 cleanup_exit(1); 1037 } 1038 memset(&sunaddr, 0, sizeof(sunaddr)); 1039 sunaddr.sun_family = AF_UNIX; 1040 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 1041 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { 1042 perror("bind"); 1043 cleanup_exit(1); 1044 } 1045 if (listen(sock, 128) < 0) { 1046 perror("listen"); 1047 cleanup_exit(1); 1048 } 1049 1050 /* 1051 * Fork, and have the parent execute the command, if any, or present 1052 * the socket data. The child continues as the authentication agent. 1053 */ 1054 if (d_flag) { 1055 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1056 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1057 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1058 SSH_AUTHSOCKET_ENV_NAME); 1059 printf("echo Agent pid %ld;\n", (long)parent_pid); 1060 goto skip; 1061 } 1062 pid = fork(); 1063 if (pid == -1) { 1064 perror("fork"); 1065 cleanup_exit(1); 1066 } 1067 if (pid != 0) { /* Parent - execute the given command. */ 1068 close(sock); 1069 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1070 if (ac == 0) { 1071 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1072 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1073 SSH_AUTHSOCKET_ENV_NAME); 1074 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1075 SSH_AGENTPID_ENV_NAME); 1076 printf("echo Agent pid %ld;\n", (long)pid); 1077 exit(0); 1078 } 1079 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1080 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1081 perror("setenv"); 1082 exit(1); 1083 } 1084 execvp(av[0], av); 1085 perror(av[0]); 1086 exit(1); 1087 } 1088 /* child */ 1089 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1090 1091 if (setsid() == -1) { 1092 error("setsid: %s", strerror(errno)); 1093 cleanup_exit(1); 1094 } 1095 1096 (void)chdir("/"); 1097 close(0); 1098 close(1); 1099 close(2); 1100 1101 /* deny core dumps, since memory contains unencrypted private keys */ 1102 rlim.rlim_cur = rlim.rlim_max = 0; 1103 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1104 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1105 cleanup_exit(1); 1106 } 1107 1108 skip: 1109 fatal_add_cleanup(cleanup_socket, NULL); 1110 new_socket(AUTH_SOCKET, sock); 1111 if (ac > 0) { 1112 signal(SIGALRM, check_parent_exists); 1113 alarm(10); 1114 } 1115 idtab_init(); 1116 if (!d_flag) 1117 signal(SIGINT, SIG_IGN); 1118 signal(SIGPIPE, SIG_IGN); 1119 signal(SIGHUP, cleanup_handler); 1120 signal(SIGTERM, cleanup_handler); 1121 nalloc = 0; 1122 1123 while (1) { 1124 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc); 1125 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) { 1126 if (errno == EINTR) 1127 continue; 1128 fatal("select: %s", strerror(errno)); 1129 } 1130 after_select(readsetp, writesetp); 1131 } 1132 /* NOTREACHED */ 1133 } 1134