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 1.85 2002/04/02 11:49:39 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 } SocketEntry; 70 71 u_int sockets_alloc = 0; 72 SocketEntry *sockets = NULL; 73 74 typedef struct identity { 75 TAILQ_ENTRY(identity) next; 76 Key *key; 77 char *comment; 78 } Identity; 79 80 typedef struct { 81 int nentries; 82 TAILQ_HEAD(idqueue, identity) idlist; 83 } Idtab; 84 85 /* private key table, one per protocol version */ 86 Idtab idtable[3]; 87 88 int max_fd = 0; 89 90 /* pid of shell == parent of agent */ 91 pid_t parent_pid = -1; 92 93 /* pathname and directory for AUTH_SOCKET */ 94 char socket_name[1024]; 95 char socket_dir[1024]; 96 97 extern char *__progname; 98 99 static void 100 idtab_init(void) 101 { 102 int i; 103 for (i = 0; i <=2; i++) { 104 TAILQ_INIT(&idtable[i].idlist); 105 idtable[i].nentries = 0; 106 } 107 } 108 109 /* return private key table for requested protocol version */ 110 static Idtab * 111 idtab_lookup(int version) 112 { 113 if (version < 1 || version > 2) 114 fatal("internal error, bad protocol version %d", version); 115 return &idtable[version]; 116 } 117 118 /* return matching private key for given public key */ 119 static Identity * 120 lookup_identity(Key *key, int version) 121 { 122 Identity *id; 123 124 Idtab *tab = idtab_lookup(version); 125 TAILQ_FOREACH(id, &tab->idlist, next) { 126 if (key_equal(key, id->key)) 127 return (id); 128 } 129 return (NULL); 130 } 131 132 static void 133 free_identity(Identity *id) 134 { 135 key_free(id->key); 136 xfree(id->comment); 137 xfree(id); 138 } 139 140 /* send list of supported public keys to 'client' */ 141 static void 142 process_request_identities(SocketEntry *e, int version) 143 { 144 Idtab *tab = idtab_lookup(version); 145 Buffer msg; 146 Identity *id; 147 148 buffer_init(&msg); 149 buffer_put_char(&msg, (version == 1) ? 150 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 151 buffer_put_int(&msg, tab->nentries); 152 TAILQ_FOREACH(id, &tab->idlist, next) { 153 if (id->key->type == KEY_RSA1) { 154 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 155 buffer_put_bignum(&msg, id->key->rsa->e); 156 buffer_put_bignum(&msg, id->key->rsa->n); 157 } else { 158 u_char *blob; 159 u_int blen; 160 key_to_blob(id->key, &blob, &blen); 161 buffer_put_string(&msg, blob, blen); 162 xfree(blob); 163 } 164 buffer_put_cstring(&msg, id->comment); 165 } 166 buffer_put_int(&e->output, buffer_len(&msg)); 167 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 168 buffer_free(&msg); 169 } 170 171 /* ssh1 only */ 172 static void 173 process_authentication_challenge1(SocketEntry *e) 174 { 175 Identity *id; 176 Key *key; 177 BIGNUM *challenge; 178 int i, len; 179 Buffer msg; 180 MD5_CTX md; 181 u_char buf[32], mdbuf[16], session_id[16]; 182 u_int response_type; 183 184 buffer_init(&msg); 185 key = key_new(KEY_RSA1); 186 if ((challenge = BN_new()) == NULL) 187 fatal("process_authentication_challenge1: BN_new failed"); 188 189 buffer_get_int(&e->input); /* ignored */ 190 buffer_get_bignum(&e->input, key->rsa->e); 191 buffer_get_bignum(&e->input, key->rsa->n); 192 buffer_get_bignum(&e->input, challenge); 193 194 /* Only protocol 1.1 is supported */ 195 if (buffer_len(&e->input) == 0) 196 goto failure; 197 buffer_get(&e->input, session_id, 16); 198 response_type = buffer_get_int(&e->input); 199 if (response_type != 1) 200 goto failure; 201 202 id = lookup_identity(key, 1); 203 if (id != NULL) { 204 Key *private = id->key; 205 /* Decrypt the challenge using the private key. */ 206 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 207 goto failure; 208 209 /* The response is MD5 of decrypted challenge plus session id. */ 210 len = BN_num_bytes(challenge); 211 if (len <= 0 || len > 32) { 212 log("process_authentication_challenge: bad challenge length %d", len); 213 goto failure; 214 } 215 memset(buf, 0, 32); 216 BN_bn2bin(challenge, buf + 32 - len); 217 MD5_Init(&md); 218 MD5_Update(&md, buf, 32); 219 MD5_Update(&md, session_id, 16); 220 MD5_Final(mdbuf, &md); 221 222 /* Send the response. */ 223 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 224 for (i = 0; i < 16; i++) 225 buffer_put_char(&msg, mdbuf[i]); 226 goto send; 227 } 228 229 failure: 230 /* Unknown identity or protocol error. Send failure. */ 231 buffer_put_char(&msg, SSH_AGENT_FAILURE); 232 send: 233 buffer_put_int(&e->output, buffer_len(&msg)); 234 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 235 key_free(key); 236 BN_clear_free(challenge); 237 buffer_free(&msg); 238 } 239 240 /* ssh2 only */ 241 static void 242 process_sign_request2(SocketEntry *e) 243 { 244 extern int datafellows; 245 Key *key; 246 u_char *blob, *data, *signature = NULL; 247 u_int blen, dlen, slen = 0; 248 int flags; 249 Buffer msg; 250 int ok = -1; 251 252 datafellows = 0; 253 254 blob = buffer_get_string(&e->input, &blen); 255 data = buffer_get_string(&e->input, &dlen); 256 257 flags = buffer_get_int(&e->input); 258 if (flags & SSH_AGENT_OLD_SIGNATURE) 259 datafellows = SSH_BUG_SIGBLOB; 260 261 key = key_from_blob(blob, blen); 262 if (key != NULL) { 263 Identity *id = lookup_identity(key, 2); 264 if (id != NULL) 265 ok = key_sign(id->key, &signature, &slen, data, dlen); 266 } 267 key_free(key); 268 buffer_init(&msg); 269 if (ok == 0) { 270 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 271 buffer_put_string(&msg, signature, slen); 272 } else { 273 buffer_put_char(&msg, SSH_AGENT_FAILURE); 274 } 275 buffer_put_int(&e->output, buffer_len(&msg)); 276 buffer_append(&e->output, buffer_ptr(&msg), 277 buffer_len(&msg)); 278 buffer_free(&msg); 279 xfree(data); 280 xfree(blob); 281 if (signature != NULL) 282 xfree(signature); 283 } 284 285 /* shared */ 286 static void 287 process_remove_identity(SocketEntry *e, int version) 288 { 289 Key *key = NULL; 290 u_char *blob; 291 u_int blen; 292 u_int bits; 293 int success = 0; 294 295 switch (version) { 296 case 1: 297 key = key_new(KEY_RSA1); 298 bits = buffer_get_int(&e->input); 299 buffer_get_bignum(&e->input, key->rsa->e); 300 buffer_get_bignum(&e->input, key->rsa->n); 301 302 if (bits != key_size(key)) 303 log("Warning: identity keysize mismatch: actual %d, announced %d", 304 key_size(key), bits); 305 break; 306 case 2: 307 blob = buffer_get_string(&e->input, &blen); 308 key = key_from_blob(blob, blen); 309 xfree(blob); 310 break; 311 } 312 if (key != NULL) { 313 Identity *id = lookup_identity(key, version); 314 if (id != NULL) { 315 /* 316 * We have this key. Free the old key. Since we 317 * don\'t want to leave empty slots in the middle of 318 * the array, we actually free the key there and move 319 * all the entries between the empty slot and the end 320 * of the array. 321 */ 322 Idtab *tab = idtab_lookup(version); 323 if (tab->nentries < 1) 324 fatal("process_remove_identity: " 325 "internal error: tab->nentries %d", 326 tab->nentries); 327 TAILQ_REMOVE(&tab->idlist, id, next); 328 free_identity(id); 329 tab->nentries--; 330 success = 1; 331 } 332 key_free(key); 333 } 334 buffer_put_int(&e->output, 1); 335 buffer_put_char(&e->output, 336 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 337 } 338 339 static void 340 process_remove_all_identities(SocketEntry *e, int version) 341 { 342 Idtab *tab = idtab_lookup(version); 343 Identity *id; 344 345 /* Loop over all identities and clear the keys. */ 346 for (id = TAILQ_FIRST(&tab->idlist); id; 347 id = TAILQ_FIRST(&tab->idlist)) { 348 TAILQ_REMOVE(&tab->idlist, id, next); 349 free_identity(id); 350 } 351 352 /* Mark that there are no identities. */ 353 tab->nentries = 0; 354 355 /* Send success. */ 356 buffer_put_int(&e->output, 1); 357 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 358 return; 359 } 360 361 static void 362 process_add_identity(SocketEntry *e, int version) 363 { 364 Key *k = NULL; 365 char *type_name; 366 char *comment; 367 int type, success = 0; 368 Idtab *tab = idtab_lookup(version); 369 370 switch (version) { 371 case 1: 372 k = key_new_private(KEY_RSA1); 373 buffer_get_int(&e->input); /* ignored */ 374 buffer_get_bignum(&e->input, k->rsa->n); 375 buffer_get_bignum(&e->input, k->rsa->e); 376 buffer_get_bignum(&e->input, k->rsa->d); 377 buffer_get_bignum(&e->input, k->rsa->iqmp); 378 379 /* SSH and SSL have p and q swapped */ 380 buffer_get_bignum(&e->input, k->rsa->q); /* p */ 381 buffer_get_bignum(&e->input, k->rsa->p); /* q */ 382 383 /* Generate additional parameters */ 384 rsa_generate_additional_parameters(k->rsa); 385 break; 386 case 2: 387 type_name = buffer_get_string(&e->input, NULL); 388 type = key_type_from_name(type_name); 389 xfree(type_name); 390 switch (type) { 391 case KEY_DSA: 392 k = key_new_private(type); 393 buffer_get_bignum2(&e->input, k->dsa->p); 394 buffer_get_bignum2(&e->input, k->dsa->q); 395 buffer_get_bignum2(&e->input, k->dsa->g); 396 buffer_get_bignum2(&e->input, k->dsa->pub_key); 397 buffer_get_bignum2(&e->input, k->dsa->priv_key); 398 break; 399 case KEY_RSA: 400 k = key_new_private(type); 401 buffer_get_bignum2(&e->input, k->rsa->n); 402 buffer_get_bignum2(&e->input, k->rsa->e); 403 buffer_get_bignum2(&e->input, k->rsa->d); 404 buffer_get_bignum2(&e->input, k->rsa->iqmp); 405 buffer_get_bignum2(&e->input, k->rsa->p); 406 buffer_get_bignum2(&e->input, k->rsa->q); 407 408 /* Generate additional parameters */ 409 rsa_generate_additional_parameters(k->rsa); 410 break; 411 default: 412 buffer_clear(&e->input); 413 goto send; 414 } 415 break; 416 } 417 comment = buffer_get_string(&e->input, NULL); 418 if (k == NULL) { 419 xfree(comment); 420 goto send; 421 } 422 success = 1; 423 if (lookup_identity(k, version) == NULL) { 424 Identity *id = xmalloc(sizeof(Identity)); 425 id->key = k; 426 id->comment = comment; 427 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 428 /* Increment the number of identities. */ 429 tab->nentries++; 430 } else { 431 key_free(k); 432 xfree(comment); 433 } 434 send: 435 buffer_put_int(&e->output, 1); 436 buffer_put_char(&e->output, 437 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 438 } 439 440 441 #ifdef SMARTCARD 442 static void 443 process_add_smartcard_key (SocketEntry *e) 444 { 445 Identity *id; 446 Idtab *tab; 447 Key **keys, *k; 448 char *sc_reader_id = NULL, *pin; 449 int i, version, success = 0; 450 451 sc_reader_id = buffer_get_string(&e->input, NULL); 452 pin = buffer_get_string(&e->input, NULL); 453 keys = sc_get_keys(sc_reader_id, pin); 454 xfree(sc_reader_id); 455 xfree(pin); 456 457 if (keys == NULL || keys[0] == NULL) { 458 error("sc_get_keys failed"); 459 goto send; 460 } 461 for (i = 0; keys[i] != NULL; i++) { 462 k = keys[i]; 463 version = k->type == KEY_RSA1 ? 1 : 2; 464 tab = idtab_lookup(version); 465 if (lookup_identity(k, version) == NULL) { 466 id = xmalloc(sizeof(Identity)); 467 id->key = k; 468 id->comment = xstrdup("smartcard key"); 469 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 470 tab->nentries++; 471 success = 1; 472 } else { 473 key_free(k); 474 } 475 keys[i] = NULL; 476 } 477 xfree(keys); 478 send: 479 buffer_put_int(&e->output, 1); 480 buffer_put_char(&e->output, 481 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 482 } 483 484 static void 485 process_remove_smartcard_key(SocketEntry *e) 486 { 487 Identity *id; 488 Idtab *tab; 489 Key **keys, *k = NULL; 490 char *sc_reader_id = NULL, *pin; 491 int i, version, success = 0; 492 493 sc_reader_id = buffer_get_string(&e->input, NULL); 494 pin = buffer_get_string(&e->input, NULL); 495 keys = sc_get_keys(sc_reader_id, pin); 496 xfree(sc_reader_id); 497 xfree(pin); 498 499 if (keys == NULL || keys[0] == NULL) { 500 error("sc_get_keys failed"); 501 goto send; 502 } 503 for (i = 0; keys[i] != NULL; i++) { 504 k = keys[i]; 505 version = k->type == KEY_RSA1 ? 1 : 2; 506 if ((id = lookup_identity(k, version)) != NULL) { 507 tab = idtab_lookup(version); 508 TAILQ_REMOVE(&tab->idlist, id, next); 509 tab->nentries--; 510 free_identity(id); 511 success = 1; 512 } 513 key_free(k); 514 keys[i] = NULL; 515 } 516 xfree(keys); 517 send: 518 buffer_put_int(&e->output, 1); 519 buffer_put_char(&e->output, 520 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 521 } 522 #endif /* SMARTCARD */ 523 524 /* dispatch incoming messages */ 525 526 static void 527 process_message(SocketEntry *e) 528 { 529 u_int msg_len; 530 u_int type; 531 u_char *cp; 532 if (buffer_len(&e->input) < 5) 533 return; /* Incomplete message. */ 534 cp = buffer_ptr(&e->input); 535 msg_len = GET_32BIT(cp); 536 if (msg_len > 256 * 1024) { 537 shutdown(e->fd, SHUT_RDWR); 538 close(e->fd); 539 e->type = AUTH_UNUSED; 540 return; 541 } 542 if (buffer_len(&e->input) < msg_len + 4) 543 return; 544 buffer_consume(&e->input, 4); 545 type = buffer_get_char(&e->input); 546 547 debug("type %d", type); 548 switch (type) { 549 /* ssh1 */ 550 case SSH_AGENTC_RSA_CHALLENGE: 551 process_authentication_challenge1(e); 552 break; 553 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 554 process_request_identities(e, 1); 555 break; 556 case SSH_AGENTC_ADD_RSA_IDENTITY: 557 process_add_identity(e, 1); 558 break; 559 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 560 process_remove_identity(e, 1); 561 break; 562 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 563 process_remove_all_identities(e, 1); 564 break; 565 /* ssh2 */ 566 case SSH2_AGENTC_SIGN_REQUEST: 567 process_sign_request2(e); 568 break; 569 case SSH2_AGENTC_REQUEST_IDENTITIES: 570 process_request_identities(e, 2); 571 break; 572 case SSH2_AGENTC_ADD_IDENTITY: 573 process_add_identity(e, 2); 574 break; 575 case SSH2_AGENTC_REMOVE_IDENTITY: 576 process_remove_identity(e, 2); 577 break; 578 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 579 process_remove_all_identities(e, 2); 580 break; 581 #ifdef SMARTCARD 582 case SSH_AGENTC_ADD_SMARTCARD_KEY: 583 process_add_smartcard_key(e); 584 break; 585 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 586 process_remove_smartcard_key(e); 587 break; 588 #endif /* SMARTCARD */ 589 default: 590 /* Unknown message. Respond with failure. */ 591 error("Unknown message %d", type); 592 buffer_clear(&e->input); 593 buffer_put_int(&e->output, 1); 594 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 595 break; 596 } 597 } 598 599 static void 600 new_socket(sock_type type, int fd) 601 { 602 u_int i, old_alloc; 603 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) 604 error("fcntl O_NONBLOCK: %s", strerror(errno)); 605 606 if (fd > max_fd) 607 max_fd = fd; 608 609 for (i = 0; i < sockets_alloc; i++) 610 if (sockets[i].type == AUTH_UNUSED) { 611 sockets[i].fd = fd; 612 sockets[i].type = type; 613 buffer_init(&sockets[i].input); 614 buffer_init(&sockets[i].output); 615 return; 616 } 617 old_alloc = sockets_alloc; 618 sockets_alloc += 10; 619 if (sockets) 620 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); 621 else 622 sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); 623 for (i = old_alloc; i < sockets_alloc; i++) 624 sockets[i].type = AUTH_UNUSED; 625 sockets[old_alloc].type = type; 626 sockets[old_alloc].fd = fd; 627 buffer_init(&sockets[old_alloc].input); 628 buffer_init(&sockets[old_alloc].output); 629 } 630 631 static int 632 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp) 633 { 634 u_int i, sz; 635 int n = 0; 636 637 for (i = 0; i < sockets_alloc; i++) { 638 switch (sockets[i].type) { 639 case AUTH_SOCKET: 640 case AUTH_CONNECTION: 641 n = MAX(n, sockets[i].fd); 642 break; 643 case AUTH_UNUSED: 644 break; 645 default: 646 fatal("Unknown socket type %d", sockets[i].type); 647 break; 648 } 649 } 650 651 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 652 if (*fdrp == NULL || sz > *nallocp) { 653 if (*fdrp) 654 xfree(*fdrp); 655 if (*fdwp) 656 xfree(*fdwp); 657 *fdrp = xmalloc(sz); 658 *fdwp = xmalloc(sz); 659 *nallocp = sz; 660 } 661 if (n < *fdl) 662 debug("XXX shrink: %d < %d", n, *fdl); 663 *fdl = n; 664 memset(*fdrp, 0, sz); 665 memset(*fdwp, 0, sz); 666 667 for (i = 0; i < sockets_alloc; i++) { 668 switch (sockets[i].type) { 669 case AUTH_SOCKET: 670 case AUTH_CONNECTION: 671 FD_SET(sockets[i].fd, *fdrp); 672 if (buffer_len(&sockets[i].output) > 0) 673 FD_SET(sockets[i].fd, *fdwp); 674 break; 675 default: 676 break; 677 } 678 } 679 return (1); 680 } 681 682 static void 683 after_select(fd_set *readset, fd_set *writeset) 684 { 685 u_int i; 686 int len, sock; 687 socklen_t slen; 688 char buf[1024]; 689 struct sockaddr_un sunaddr; 690 691 for (i = 0; i < sockets_alloc; i++) 692 switch (sockets[i].type) { 693 case AUTH_UNUSED: 694 break; 695 case AUTH_SOCKET: 696 if (FD_ISSET(sockets[i].fd, readset)) { 697 slen = sizeof(sunaddr); 698 sock = accept(sockets[i].fd, 699 (struct sockaddr *) &sunaddr, &slen); 700 if (sock < 0) { 701 error("accept from AUTH_SOCKET: %s", 702 strerror(errno)); 703 break; 704 } 705 new_socket(AUTH_CONNECTION, sock); 706 } 707 break; 708 case AUTH_CONNECTION: 709 if (buffer_len(&sockets[i].output) > 0 && 710 FD_ISSET(sockets[i].fd, writeset)) { 711 do { 712 len = write(sockets[i].fd, 713 buffer_ptr(&sockets[i].output), 714 buffer_len(&sockets[i].output)); 715 if (len == -1 && (errno == EAGAIN || 716 errno == EINTR)) 717 continue; 718 break; 719 } while (1); 720 if (len <= 0) { 721 shutdown(sockets[i].fd, SHUT_RDWR); 722 close(sockets[i].fd); 723 sockets[i].type = AUTH_UNUSED; 724 buffer_free(&sockets[i].input); 725 buffer_free(&sockets[i].output); 726 break; 727 } 728 buffer_consume(&sockets[i].output, len); 729 } 730 if (FD_ISSET(sockets[i].fd, readset)) { 731 do { 732 len = read(sockets[i].fd, buf, sizeof(buf)); 733 if (len == -1 && (errno == EAGAIN || 734 errno == EINTR)) 735 continue; 736 break; 737 } while (1); 738 if (len <= 0) { 739 shutdown(sockets[i].fd, SHUT_RDWR); 740 close(sockets[i].fd); 741 sockets[i].type = AUTH_UNUSED; 742 buffer_free(&sockets[i].input); 743 buffer_free(&sockets[i].output); 744 break; 745 } 746 buffer_append(&sockets[i].input, buf, len); 747 process_message(&sockets[i]); 748 } 749 break; 750 default: 751 fatal("Unknown type %d", sockets[i].type); 752 } 753 } 754 755 static void 756 cleanup_socket(void *p) 757 { 758 if (socket_name[0]) 759 unlink(socket_name); 760 if (socket_dir[0]) 761 rmdir(socket_dir); 762 } 763 764 static void 765 cleanup_exit(int i) 766 { 767 cleanup_socket(NULL); 768 exit(i); 769 } 770 771 static void 772 cleanup_handler(int sig) 773 { 774 cleanup_socket(NULL); 775 _exit(2); 776 } 777 778 static void 779 check_parent_exists(int sig) 780 { 781 int save_errno = errno; 782 783 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 784 /* printf("Parent has died - Authentication agent exiting.\n"); */ 785 cleanup_handler(sig); /* safe */ 786 } 787 signal(SIGALRM, check_parent_exists); 788 alarm(10); 789 errno = save_errno; 790 } 791 792 static void 793 usage(void) 794 { 795 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n", 796 __progname); 797 fprintf(stderr, "Options:\n"); 798 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 799 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 800 fprintf(stderr, " -k Kill the current agent.\n"); 801 fprintf(stderr, " -d Debug mode.\n"); 802 exit(1); 803 } 804 805 int 806 main(int ac, char **av) 807 { 808 int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc; 809 struct sockaddr_un sunaddr; 810 struct rlimit rlim; 811 pid_t pid; 812 char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; 813 extern int optind; 814 fd_set *readsetp = NULL, *writesetp = NULL; 815 816 SSLeay_add_all_algorithms(); 817 818 while ((ch = getopt(ac, av, "cdks")) != -1) { 819 switch (ch) { 820 case 'c': 821 if (s_flag) 822 usage(); 823 c_flag++; 824 break; 825 case 'k': 826 k_flag++; 827 break; 828 case 's': 829 if (c_flag) 830 usage(); 831 s_flag++; 832 break; 833 case 'd': 834 if (d_flag) 835 usage(); 836 d_flag++; 837 break; 838 default: 839 usage(); 840 } 841 } 842 ac -= optind; 843 av += optind; 844 845 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 846 usage(); 847 848 if (ac == 0 && !c_flag && !s_flag) { 849 shell = getenv("SHELL"); 850 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 851 c_flag = 1; 852 } 853 if (k_flag) { 854 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 855 if (pidstr == NULL) { 856 fprintf(stderr, "%s not set, cannot kill agent\n", 857 SSH_AGENTPID_ENV_NAME); 858 exit(1); 859 } 860 pid = atoi(pidstr); 861 if (pid < 1) { 862 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 863 SSH_AGENTPID_ENV_NAME, pidstr); 864 exit(1); 865 } 866 if (kill(pid, SIGTERM) == -1) { 867 perror("kill"); 868 exit(1); 869 } 870 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 871 printf(format, SSH_AUTHSOCKET_ENV_NAME); 872 printf(format, SSH_AGENTPID_ENV_NAME); 873 printf("echo Agent pid %d killed;\n", pid); 874 exit(0); 875 } 876 parent_pid = getpid(); 877 878 /* Create private directory for agent socket */ 879 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); 880 if (mkdtemp(socket_dir) == NULL) { 881 perror("mkdtemp: private socket dir"); 882 exit(1); 883 } 884 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, 885 parent_pid); 886 887 /* 888 * Create socket early so it will exist before command gets run from 889 * the parent. 890 */ 891 sock = socket(AF_UNIX, SOCK_STREAM, 0); 892 if (sock < 0) { 893 perror("socket"); 894 cleanup_exit(1); 895 } 896 memset(&sunaddr, 0, sizeof(sunaddr)); 897 sunaddr.sun_family = AF_UNIX; 898 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 899 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { 900 perror("bind"); 901 cleanup_exit(1); 902 } 903 if (listen(sock, 5) < 0) { 904 perror("listen"); 905 cleanup_exit(1); 906 } 907 908 /* 909 * Fork, and have the parent execute the command, if any, or present 910 * the socket data. The child continues as the authentication agent. 911 */ 912 if (d_flag) { 913 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 914 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 915 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 916 SSH_AUTHSOCKET_ENV_NAME); 917 printf("echo Agent pid %d;\n", parent_pid); 918 goto skip; 919 } 920 pid = fork(); 921 if (pid == -1) { 922 perror("fork"); 923 cleanup_exit(1); 924 } 925 if (pid != 0) { /* Parent - execute the given command. */ 926 close(sock); 927 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid); 928 if (ac == 0) { 929 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 930 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 931 SSH_AUTHSOCKET_ENV_NAME); 932 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 933 SSH_AGENTPID_ENV_NAME); 934 printf("echo Agent pid %d;\n", pid); 935 exit(0); 936 } 937 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 938 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 939 perror("setenv"); 940 exit(1); 941 } 942 execvp(av[0], av); 943 perror(av[0]); 944 exit(1); 945 } 946 /* child */ 947 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 948 949 if (setsid() == -1) { 950 error("setsid: %s", strerror(errno)); 951 cleanup_exit(1); 952 } 953 954 (void)chdir("/"); 955 close(0); 956 close(1); 957 close(2); 958 959 /* deny core dumps, since memory contains unencrypted private keys */ 960 rlim.rlim_cur = rlim.rlim_max = 0; 961 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 962 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 963 cleanup_exit(1); 964 } 965 966 skip: 967 fatal_add_cleanup(cleanup_socket, NULL); 968 new_socket(AUTH_SOCKET, sock); 969 if (ac > 0) { 970 signal(SIGALRM, check_parent_exists); 971 alarm(10); 972 } 973 idtab_init(); 974 if (!d_flag) 975 signal(SIGINT, SIG_IGN); 976 signal(SIGPIPE, SIG_IGN); 977 signal(SIGHUP, cleanup_handler); 978 signal(SIGTERM, cleanup_handler); 979 nalloc = 0; 980 981 while (1) { 982 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc); 983 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) { 984 if (errno == EINTR) 985 continue; 986 fatal("select: %s", strerror(errno)); 987 } 988 after_select(readsetp, writesetp); 989 } 990 /* NOTREACHED */ 991 } 992