1 /* $OpenBSD: ssh-agent.c,v 1.54 2001/04/03 13:56:11 stevesk Exp $ */ 2 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * The authentication agent program. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * SSH2 implementation, 16 * Copyright (c) 2000 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 RCSID("$OpenBSD: ssh-agent.c,v 1.54 2001/04/03 13:56:11 stevesk Exp $"); 41 RCSID("$FreeBSD$"); 42 43 #include <openssl/evp.h> 44 #include <openssl/md5.h> 45 46 #include "ssh.h" 47 #include "rsa.h" 48 #include "buffer.h" 49 #include "bufaux.h" 50 #include "xmalloc.h" 51 #include "packet.h" 52 #include "getput.h" 53 #include "mpaux.h" 54 #include "key.h" 55 #include "authfd.h" 56 #include "cipher.h" 57 #include "kex.h" 58 #include "compat.h" 59 #include "log.h" 60 61 typedef struct { 62 int fd; 63 enum { 64 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION 65 } type; 66 Buffer input; 67 Buffer output; 68 } SocketEntry; 69 70 u_int sockets_alloc = 0; 71 SocketEntry *sockets = NULL; 72 73 typedef struct { 74 Key *key; 75 char *comment; 76 } Identity; 77 78 typedef struct { 79 int nentries; 80 Identity *identities; 81 } Idtab; 82 83 /* private key table, one per protocol version */ 84 Idtab idtable[3]; 85 86 int max_fd = 0; 87 88 /* pid of shell == parent of agent */ 89 pid_t parent_pid = -1; 90 91 /* pathname and directory for AUTH_SOCKET */ 92 char socket_name[1024]; 93 char socket_dir[1024]; 94 95 extern char *__progname; 96 97 int prepare_select(fd_set **, fd_set **, int *); 98 99 void 100 idtab_init(void) 101 { 102 int i; 103 for (i = 0; i <=2; i++){ 104 idtable[i].identities = NULL; 105 idtable[i].nentries = 0; 106 } 107 } 108 109 /* return private key table for requested protocol version */ 110 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 Key * 120 lookup_private_key(Key *key, int *idx, int version) 121 { 122 int i; 123 Idtab *tab = idtab_lookup(version); 124 for (i = 0; i < tab->nentries; i++) { 125 if (key_equal(key, tab->identities[i].key)) { 126 if (idx != NULL) 127 *idx = i; 128 return tab->identities[i].key; 129 } 130 } 131 return NULL; 132 } 133 134 /* send list of supported public keys to 'client' */ 135 void 136 process_request_identities(SocketEntry *e, int version) 137 { 138 Idtab *tab = idtab_lookup(version); 139 Buffer msg; 140 int i; 141 142 buffer_init(&msg); 143 buffer_put_char(&msg, (version == 1) ? 144 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 145 buffer_put_int(&msg, tab->nentries); 146 for (i = 0; i < tab->nentries; i++) { 147 Identity *id = &tab->identities[i]; 148 if (id->key->type == KEY_RSA1) { 149 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 150 buffer_put_bignum(&msg, id->key->rsa->e); 151 buffer_put_bignum(&msg, id->key->rsa->n); 152 } else { 153 u_char *blob; 154 u_int blen; 155 key_to_blob(id->key, &blob, &blen); 156 buffer_put_string(&msg, blob, blen); 157 xfree(blob); 158 } 159 buffer_put_cstring(&msg, id->comment); 160 } 161 buffer_put_int(&e->output, buffer_len(&msg)); 162 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 163 buffer_free(&msg); 164 } 165 166 /* ssh1 only */ 167 void 168 process_authentication_challenge1(SocketEntry *e) 169 { 170 Key *key, *private; 171 BIGNUM *challenge; 172 int i, len; 173 Buffer msg; 174 MD5_CTX md; 175 u_char buf[32], mdbuf[16], session_id[16]; 176 u_int response_type; 177 178 buffer_init(&msg); 179 key = key_new(KEY_RSA1); 180 challenge = BN_new(); 181 182 buffer_get_int(&e->input); /* ignored */ 183 buffer_get_bignum(&e->input, key->rsa->e); 184 buffer_get_bignum(&e->input, key->rsa->n); 185 buffer_get_bignum(&e->input, challenge); 186 187 /* Only protocol 1.1 is supported */ 188 if (buffer_len(&e->input) == 0) 189 goto failure; 190 buffer_get(&e->input, (char *) session_id, 16); 191 response_type = buffer_get_int(&e->input); 192 if (response_type != 1) 193 goto failure; 194 195 private = lookup_private_key(key, NULL, 1); 196 if (private != NULL) { 197 /* Decrypt the challenge using the private key. */ 198 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 199 goto failure; 200 201 /* The response is MD5 of decrypted challenge plus session id. */ 202 len = BN_num_bytes(challenge); 203 if (len <= 0 || len > 32) { 204 log("process_authentication_challenge: bad challenge length %d", len); 205 goto failure; 206 } 207 memset(buf, 0, 32); 208 BN_bn2bin(challenge, buf + 32 - len); 209 MD5_Init(&md); 210 MD5_Update(&md, buf, 32); 211 MD5_Update(&md, session_id, 16); 212 MD5_Final(mdbuf, &md); 213 214 /* Send the response. */ 215 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 216 for (i = 0; i < 16; i++) 217 buffer_put_char(&msg, mdbuf[i]); 218 goto send; 219 } 220 221 failure: 222 /* Unknown identity or protocol error. Send failure. */ 223 buffer_put_char(&msg, SSH_AGENT_FAILURE); 224 send: 225 buffer_put_int(&e->output, buffer_len(&msg)); 226 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 227 key_free(key); 228 BN_clear_free(challenge); 229 buffer_free(&msg); 230 } 231 232 /* ssh2 only */ 233 void 234 process_sign_request2(SocketEntry *e) 235 { 236 extern int datafellows; 237 Key *key, *private; 238 u_char *blob, *data, *signature = NULL; 239 u_int blen, dlen, slen = 0; 240 int flags; 241 Buffer msg; 242 int ok = -1; 243 244 datafellows = 0; 245 246 blob = buffer_get_string(&e->input, &blen); 247 data = buffer_get_string(&e->input, &dlen); 248 249 flags = buffer_get_int(&e->input); 250 if (flags & SSH_AGENT_OLD_SIGNATURE) 251 datafellows = SSH_BUG_SIGBLOB; 252 253 key = key_from_blob(blob, blen); 254 if (key != NULL) { 255 private = lookup_private_key(key, NULL, 2); 256 if (private != NULL) 257 ok = key_sign(private, &signature, &slen, data, dlen); 258 } 259 key_free(key); 260 buffer_init(&msg); 261 if (ok == 0) { 262 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 263 buffer_put_string(&msg, signature, slen); 264 } else { 265 buffer_put_char(&msg, SSH_AGENT_FAILURE); 266 } 267 buffer_put_int(&e->output, buffer_len(&msg)); 268 buffer_append(&e->output, buffer_ptr(&msg), 269 buffer_len(&msg)); 270 buffer_free(&msg); 271 xfree(data); 272 xfree(blob); 273 if (signature != NULL) 274 xfree(signature); 275 } 276 277 /* shared */ 278 void 279 process_remove_identity(SocketEntry *e, int version) 280 { 281 Key *key = NULL, *private; 282 u_char *blob; 283 u_int blen; 284 u_int bits; 285 int success = 0; 286 287 switch(version){ 288 case 1: 289 key = key_new(KEY_RSA1); 290 bits = buffer_get_int(&e->input); 291 buffer_get_bignum(&e->input, key->rsa->e); 292 buffer_get_bignum(&e->input, key->rsa->n); 293 294 if (bits != key_size(key)) 295 log("Warning: identity keysize mismatch: actual %d, announced %d", 296 key_size(key), bits); 297 break; 298 case 2: 299 blob = buffer_get_string(&e->input, &blen); 300 key = key_from_blob(blob, blen); 301 xfree(blob); 302 break; 303 } 304 if (key != NULL) { 305 int idx; 306 private = lookup_private_key(key, &idx, version); 307 if (private != NULL) { 308 /* 309 * We have this key. Free the old key. Since we 310 * don\'t want to leave empty slots in the middle of 311 * the array, we actually free the key there and move 312 * all the entries between the empty slot and the end 313 * of the array. 314 */ 315 Idtab *tab = idtab_lookup(version); 316 key_free(tab->identities[idx].key); 317 xfree(tab->identities[idx].comment); 318 if (tab->nentries < 1) 319 fatal("process_remove_identity: " 320 "internal error: tab->nentries %d", 321 tab->nentries); 322 if (idx != tab->nentries - 1) { 323 int i; 324 for (i = idx; i < tab->nentries - 1; i++) 325 tab->identities[i] = tab->identities[i+1]; 326 } 327 tab->identities[tab->nentries - 1].key = NULL; 328 tab->identities[tab->nentries - 1].comment = NULL; 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 void 340 process_remove_all_identities(SocketEntry *e, int version) 341 { 342 u_int i; 343 Idtab *tab = idtab_lookup(version); 344 345 /* Loop over all identities and clear the keys. */ 346 for (i = 0; i < tab->nentries; i++) { 347 key_free(tab->identities[i].key); 348 xfree(tab->identities[i].comment); 349 } 350 351 /* Mark that there are no identities. */ 352 tab->nentries = 0; 353 354 /* Send success. */ 355 buffer_put_int(&e->output, 1); 356 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 357 return; 358 } 359 360 void 361 process_add_identity(SocketEntry *e, int version) 362 { 363 Key *k = NULL; 364 char *type_name; 365 char *comment; 366 int type, success = 0; 367 Idtab *tab = idtab_lookup(version); 368 369 switch (version) { 370 case 1: 371 k = key_new_private(KEY_RSA1); 372 buffer_get_int(&e->input); /* ignored */ 373 buffer_get_bignum(&e->input, k->rsa->n); 374 buffer_get_bignum(&e->input, k->rsa->e); 375 buffer_get_bignum(&e->input, k->rsa->d); 376 buffer_get_bignum(&e->input, k->rsa->iqmp); 377 378 /* SSH and SSL have p and q swapped */ 379 buffer_get_bignum(&e->input, k->rsa->q); /* p */ 380 buffer_get_bignum(&e->input, k->rsa->p); /* q */ 381 382 /* Generate additional parameters */ 383 generate_additional_parameters(k->rsa); 384 break; 385 case 2: 386 type_name = buffer_get_string(&e->input, NULL); 387 type = key_type_from_name(type_name); 388 xfree(type_name); 389 switch(type) { 390 case KEY_DSA: 391 k = key_new_private(type); 392 buffer_get_bignum2(&e->input, k->dsa->p); 393 buffer_get_bignum2(&e->input, k->dsa->q); 394 buffer_get_bignum2(&e->input, k->dsa->g); 395 buffer_get_bignum2(&e->input, k->dsa->pub_key); 396 buffer_get_bignum2(&e->input, k->dsa->priv_key); 397 break; 398 case KEY_RSA: 399 k = key_new_private(type); 400 buffer_get_bignum2(&e->input, k->rsa->n); 401 buffer_get_bignum2(&e->input, k->rsa->e); 402 buffer_get_bignum2(&e->input, k->rsa->d); 403 buffer_get_bignum2(&e->input, k->rsa->iqmp); 404 buffer_get_bignum2(&e->input, k->rsa->p); 405 buffer_get_bignum2(&e->input, k->rsa->q); 406 407 /* Generate additional parameters */ 408 generate_additional_parameters(k->rsa); 409 break; 410 default: 411 buffer_clear(&e->input); 412 goto send; 413 } 414 break; 415 } 416 comment = buffer_get_string(&e->input, NULL); 417 if (k == NULL) { 418 xfree(comment); 419 goto send; 420 } 421 success = 1; 422 if (lookup_private_key(k, NULL, version) == NULL) { 423 if (tab->nentries == 0) 424 tab->identities = xmalloc(sizeof(Identity)); 425 else 426 tab->identities = xrealloc(tab->identities, 427 (tab->nentries + 1) * sizeof(Identity)); 428 tab->identities[tab->nentries].key = k; 429 tab->identities[tab->nentries].comment = comment; 430 /* Increment the number of identities. */ 431 tab->nentries++; 432 } else { 433 key_free(k); 434 xfree(comment); 435 } 436 send: 437 buffer_put_int(&e->output, 1); 438 buffer_put_char(&e->output, 439 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 440 } 441 442 /* dispatch incoming messages */ 443 444 void 445 process_message(SocketEntry *e) 446 { 447 u_int msg_len; 448 u_int type; 449 u_char *cp; 450 if (buffer_len(&e->input) < 5) 451 return; /* Incomplete message. */ 452 cp = (u_char *) buffer_ptr(&e->input); 453 msg_len = GET_32BIT(cp); 454 if (msg_len > 256 * 1024) { 455 shutdown(e->fd, SHUT_RDWR); 456 close(e->fd); 457 e->type = AUTH_UNUSED; 458 return; 459 } 460 if (buffer_len(&e->input) < msg_len + 4) 461 return; 462 buffer_consume(&e->input, 4); 463 type = buffer_get_char(&e->input); 464 465 switch (type) { 466 /* ssh1 */ 467 case SSH_AGENTC_RSA_CHALLENGE: 468 process_authentication_challenge1(e); 469 break; 470 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 471 process_request_identities(e, 1); 472 break; 473 case SSH_AGENTC_ADD_RSA_IDENTITY: 474 process_add_identity(e, 1); 475 break; 476 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 477 process_remove_identity(e, 1); 478 break; 479 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 480 process_remove_all_identities(e, 1); 481 break; 482 /* ssh2 */ 483 case SSH2_AGENTC_SIGN_REQUEST: 484 process_sign_request2(e); 485 break; 486 case SSH2_AGENTC_REQUEST_IDENTITIES: 487 process_request_identities(e, 2); 488 break; 489 case SSH2_AGENTC_ADD_IDENTITY: 490 process_add_identity(e, 2); 491 break; 492 case SSH2_AGENTC_REMOVE_IDENTITY: 493 process_remove_identity(e, 2); 494 break; 495 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 496 process_remove_all_identities(e, 2); 497 break; 498 default: 499 /* Unknown message. Respond with failure. */ 500 error("Unknown message %d", type); 501 buffer_clear(&e->input); 502 buffer_put_int(&e->output, 1); 503 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 504 break; 505 } 506 } 507 508 void 509 new_socket(int type, int fd) 510 { 511 u_int i, old_alloc; 512 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) 513 error("fcntl O_NONBLOCK: %s", strerror(errno)); 514 515 if (fd > max_fd) 516 max_fd = fd; 517 518 for (i = 0; i < sockets_alloc; i++) 519 if (sockets[i].type == AUTH_UNUSED) { 520 sockets[i].fd = fd; 521 sockets[i].type = type; 522 buffer_init(&sockets[i].input); 523 buffer_init(&sockets[i].output); 524 return; 525 } 526 old_alloc = sockets_alloc; 527 sockets_alloc += 10; 528 if (sockets) 529 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); 530 else 531 sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); 532 for (i = old_alloc; i < sockets_alloc; i++) 533 sockets[i].type = AUTH_UNUSED; 534 sockets[old_alloc].type = type; 535 sockets[old_alloc].fd = fd; 536 buffer_init(&sockets[old_alloc].input); 537 buffer_init(&sockets[old_alloc].output); 538 } 539 540 int 541 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl) 542 { 543 u_int i, sz; 544 int n = 0; 545 546 for (i = 0; i < sockets_alloc; i++) { 547 switch (sockets[i].type) { 548 case AUTH_SOCKET: 549 case AUTH_CONNECTION: 550 n = MAX(n, sockets[i].fd); 551 break; 552 case AUTH_UNUSED: 553 break; 554 default: 555 fatal("Unknown socket type %d", sockets[i].type); 556 break; 557 } 558 } 559 560 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 561 if (*fdrp == NULL || n > *fdl) { 562 if (*fdrp) 563 xfree(*fdrp); 564 if (*fdwp) 565 xfree(*fdwp); 566 *fdrp = xmalloc(sz); 567 *fdwp = xmalloc(sz); 568 *fdl = n; 569 } 570 memset(*fdrp, 0, sz); 571 memset(*fdwp, 0, sz); 572 573 for (i = 0; i < sockets_alloc; i++) { 574 switch (sockets[i].type) { 575 case AUTH_SOCKET: 576 case AUTH_CONNECTION: 577 FD_SET(sockets[i].fd, *fdrp); 578 if (buffer_len(&sockets[i].output) > 0) 579 FD_SET(sockets[i].fd, *fdwp); 580 break; 581 default: 582 break; 583 } 584 } 585 return (1); 586 } 587 588 void 589 after_select(fd_set *readset, fd_set *writeset) 590 { 591 u_int i; 592 int len, sock; 593 socklen_t slen; 594 char buf[1024]; 595 struct sockaddr_un sunaddr; 596 597 for (i = 0; i < sockets_alloc; i++) 598 switch (sockets[i].type) { 599 case AUTH_UNUSED: 600 break; 601 case AUTH_SOCKET: 602 if (FD_ISSET(sockets[i].fd, readset)) { 603 slen = sizeof(sunaddr); 604 sock = accept(sockets[i].fd, 605 (struct sockaddr *) &sunaddr, &slen); 606 if (sock < 0) { 607 perror("accept from AUTH_SOCKET"); 608 break; 609 } 610 new_socket(AUTH_CONNECTION, sock); 611 } 612 break; 613 case AUTH_CONNECTION: 614 if (buffer_len(&sockets[i].output) > 0 && 615 FD_ISSET(sockets[i].fd, writeset)) { 616 do { 617 len = write(sockets[i].fd, 618 buffer_ptr(&sockets[i].output), 619 buffer_len(&sockets[i].output)); 620 if (len == -1 && (errno == EAGAIN || 621 errno == EINTR)) 622 continue; 623 break; 624 } while (1); 625 if (len <= 0) { 626 shutdown(sockets[i].fd, SHUT_RDWR); 627 close(sockets[i].fd); 628 sockets[i].type = AUTH_UNUSED; 629 buffer_free(&sockets[i].input); 630 buffer_free(&sockets[i].output); 631 break; 632 } 633 buffer_consume(&sockets[i].output, len); 634 } 635 if (FD_ISSET(sockets[i].fd, readset)) { 636 do { 637 len = read(sockets[i].fd, buf, sizeof(buf)); 638 if (len == -1 && (errno == EAGAIN || 639 errno == EINTR)) 640 continue; 641 break; 642 } while (1); 643 if (len <= 0) { 644 shutdown(sockets[i].fd, SHUT_RDWR); 645 close(sockets[i].fd); 646 sockets[i].type = AUTH_UNUSED; 647 buffer_free(&sockets[i].input); 648 buffer_free(&sockets[i].output); 649 break; 650 } 651 buffer_append(&sockets[i].input, buf, len); 652 process_message(&sockets[i]); 653 } 654 break; 655 default: 656 fatal("Unknown type %d", sockets[i].type); 657 } 658 } 659 660 void 661 check_parent_exists(int sig) 662 { 663 int save_errno = errno; 664 665 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 666 /* printf("Parent has died - Authentication agent exiting.\n"); */ 667 exit(1); 668 } 669 signal(SIGALRM, check_parent_exists); 670 alarm(10); 671 errno = save_errno; 672 } 673 674 void 675 cleanup_socket(void) 676 { 677 if (socket_name[0]) 678 unlink(socket_name); 679 if (socket_dir[0]) 680 rmdir(socket_dir); 681 } 682 683 void 684 cleanup_exit(int i) 685 { 686 cleanup_socket(); 687 exit(i); 688 } 689 690 void 691 cleanup_handler(int sig) 692 { 693 cleanup_socket(); 694 _exit(2); 695 } 696 697 void 698 usage(void) 699 { 700 fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION); 701 fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n", 702 __progname); 703 exit(1); 704 } 705 706 int 707 main(int ac, char **av) 708 { 709 int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch; 710 struct sockaddr_un sunaddr; 711 struct rlimit rlim; 712 pid_t pid; 713 char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; 714 extern int optind; 715 fd_set *readsetp = NULL, *writesetp = NULL; 716 717 SSLeay_add_all_algorithms(); 718 719 while ((ch = getopt(ac, av, "cks")) != -1) { 720 switch (ch) { 721 case 'c': 722 if (s_flag) 723 usage(); 724 c_flag++; 725 break; 726 case 'k': 727 k_flag++; 728 break; 729 case 's': 730 if (c_flag) 731 usage(); 732 s_flag++; 733 break; 734 default: 735 usage(); 736 } 737 } 738 ac -= optind; 739 av += optind; 740 741 if (ac > 0 && (c_flag || k_flag || s_flag)) 742 usage(); 743 744 if (ac == 0 && !c_flag && !k_flag && !s_flag) { 745 shell = getenv("SHELL"); 746 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 747 c_flag = 1; 748 } 749 if (k_flag) { 750 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 751 if (pidstr == NULL) { 752 fprintf(stderr, "%s not set, cannot kill agent\n", 753 SSH_AGENTPID_ENV_NAME); 754 exit(1); 755 } 756 pid = atoi(pidstr); 757 if (pid < 1) { 758 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 759 SSH_AGENTPID_ENV_NAME, pidstr); 760 exit(1); 761 } 762 if (kill(pid, SIGTERM) == -1) { 763 perror("kill"); 764 exit(1); 765 } 766 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 767 printf(format, SSH_AUTHSOCKET_ENV_NAME); 768 printf(format, SSH_AGENTPID_ENV_NAME); 769 printf("echo Agent pid %d killed;\n", pid); 770 exit(0); 771 } 772 parent_pid = getpid(); 773 774 /* Create private directory for agent socket */ 775 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); 776 if (mkdtemp(socket_dir) == NULL) { 777 perror("mkdtemp: private socket dir"); 778 exit(1); 779 } 780 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, 781 parent_pid); 782 783 /* 784 * Create socket early so it will exist before command gets run from 785 * the parent. 786 */ 787 sock = socket(AF_UNIX, SOCK_STREAM, 0); 788 if (sock < 0) { 789 perror("socket"); 790 cleanup_exit(1); 791 } 792 memset(&sunaddr, 0, sizeof(sunaddr)); 793 sunaddr.sun_family = AF_UNIX; 794 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 795 sunaddr.sun_len = SUN_LEN(&sunaddr) + 1; 796 if (bind(sock, (struct sockaddr *)&sunaddr, sunaddr.sun_len) < 0) { 797 perror("bind"); 798 cleanup_exit(1); 799 } 800 if (listen(sock, 5) < 0) { 801 perror("listen"); 802 cleanup_exit(1); 803 } 804 805 /* 806 * Fork, and have the parent execute the command, if any, or present 807 * the socket data. The child continues as the authentication agent. 808 */ 809 pid = fork(); 810 if (pid == -1) { 811 perror("fork"); 812 exit(1); 813 } 814 if (pid != 0) { /* Parent - execute the given command. */ 815 close(sock); 816 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid); 817 if (ac == 0) { 818 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 819 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 820 SSH_AUTHSOCKET_ENV_NAME); 821 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 822 SSH_AGENTPID_ENV_NAME); 823 printf("echo Agent pid %d;\n", pid); 824 exit(0); 825 } 826 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 827 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 828 perror("setenv"); 829 exit(1); 830 } 831 execvp(av[0], av); 832 perror(av[0]); 833 exit(1); 834 } 835 close(0); 836 close(1); 837 close(2); 838 839 /* deny core dumps, since memory contains unencrypted private keys */ 840 rlim.rlim_cur = rlim.rlim_max = 0; 841 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 842 perror("setrlimit rlimit_core failed"); 843 cleanup_exit(1); 844 } 845 if (setsid() == -1) { 846 perror("setsid"); 847 cleanup_exit(1); 848 } 849 if (atexit(cleanup_socket) < 0) { 850 perror("atexit"); 851 cleanup_exit(1); 852 } 853 new_socket(AUTH_SOCKET, sock); 854 if (ac > 0) { 855 signal(SIGALRM, check_parent_exists); 856 alarm(10); 857 } 858 idtab_init(); 859 signal(SIGINT, SIG_IGN); 860 signal(SIGPIPE, SIG_IGN); 861 signal(SIGHUP, cleanup_handler); 862 signal(SIGTERM, cleanup_handler); 863 while (1) { 864 prepare_select(&readsetp, &writesetp, &max_fd); 865 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) { 866 if (errno == EINTR) 867 continue; 868 exit(1); 869 } 870 after_select(readsetp, writesetp); 871 } 872 /* NOTREACHED */ 873 } 874