1 /* $OpenBSD: ssh-agent.c,v 1.81 2002/02/05 15:50:12 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 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include "includes.h" 39 #include <sys/queue.h> 40 RCSID("$OpenBSD: ssh-agent.c,v 1.81 2002/02/05 15:50:12 stevesk Exp $"); 41 42 #include <openssl/evp.h> 43 #include <openssl/md5.h> 44 45 #include "ssh.h" 46 #include "rsa.h" 47 #include "buffer.h" 48 #include "bufaux.h" 49 #include "xmalloc.h" 50 #include "getput.h" 51 #include "key.h" 52 #include "authfd.h" 53 #include "compat.h" 54 #include "log.h" 55 56 #ifdef SMARTCARD 57 #include <openssl/engine.h> 58 #include "scard.h" 59 #endif 60 61 typedef enum { 62 AUTH_UNUSED, 63 AUTH_SOCKET, 64 AUTH_CONNECTION 65 } sock_type; 66 67 typedef struct { 68 int fd; 69 sock_type type; 70 Buffer input; 71 Buffer output; 72 } SocketEntry; 73 74 u_int sockets_alloc = 0; 75 SocketEntry *sockets = NULL; 76 77 typedef struct identity { 78 TAILQ_ENTRY(identity) next; 79 Key *key; 80 char *comment; 81 } Identity; 82 83 typedef struct { 84 int nentries; 85 TAILQ_HEAD(idqueue, identity) idlist; 86 } Idtab; 87 88 /* private key table, one per protocol version */ 89 Idtab idtable[3]; 90 91 int max_fd = 0; 92 93 /* pid of shell == parent of agent */ 94 pid_t parent_pid = -1; 95 96 /* pathname and directory for AUTH_SOCKET */ 97 char socket_name[1024]; 98 char socket_dir[1024]; 99 100 extern char *__progname; 101 102 static void 103 idtab_init(void) 104 { 105 int i; 106 for (i = 0; i <=2; i++) { 107 TAILQ_INIT(&idtable[i].idlist); 108 idtable[i].nentries = 0; 109 } 110 } 111 112 /* return private key table for requested protocol version */ 113 static Idtab * 114 idtab_lookup(int version) 115 { 116 if (version < 1 || version > 2) 117 fatal("internal error, bad protocol version %d", version); 118 return &idtable[version]; 119 } 120 121 /* return matching private key for given public key */ 122 static Identity * 123 lookup_identity(Key *key, int version) 124 { 125 Identity *id; 126 127 Idtab *tab = idtab_lookup(version); 128 TAILQ_FOREACH(id, &tab->idlist, next) { 129 if (key_equal(key, id->key)) 130 return (id); 131 } 132 return (NULL); 133 } 134 135 static void 136 free_identity(Identity *id) 137 { 138 key_free(id->key); 139 xfree(id->comment); 140 xfree(id); 141 } 142 143 /* send list of supported public keys to 'client' */ 144 static void 145 process_request_identities(SocketEntry *e, int version) 146 { 147 Idtab *tab = idtab_lookup(version); 148 Buffer msg; 149 Identity *id; 150 151 buffer_init(&msg); 152 buffer_put_char(&msg, (version == 1) ? 153 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 154 buffer_put_int(&msg, tab->nentries); 155 TAILQ_FOREACH(id, &tab->idlist, next) { 156 if (id->key->type == KEY_RSA1) { 157 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 158 buffer_put_bignum(&msg, id->key->rsa->e); 159 buffer_put_bignum(&msg, id->key->rsa->n); 160 } else { 161 u_char *blob; 162 u_int blen; 163 key_to_blob(id->key, &blob, &blen); 164 buffer_put_string(&msg, blob, blen); 165 xfree(blob); 166 } 167 buffer_put_cstring(&msg, id->comment); 168 } 169 buffer_put_int(&e->output, buffer_len(&msg)); 170 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 171 buffer_free(&msg); 172 } 173 174 /* ssh1 only */ 175 static void 176 process_authentication_challenge1(SocketEntry *e) 177 { 178 Identity *id; 179 Key *key; 180 BIGNUM *challenge; 181 int i, len; 182 Buffer msg; 183 MD5_CTX md; 184 u_char buf[32], mdbuf[16], session_id[16]; 185 u_int response_type; 186 187 buffer_init(&msg); 188 key = key_new(KEY_RSA1); 189 if ((challenge = BN_new()) == NULL) 190 fatal("process_authentication_challenge1: BN_new failed"); 191 192 buffer_get_int(&e->input); /* ignored */ 193 buffer_get_bignum(&e->input, key->rsa->e); 194 buffer_get_bignum(&e->input, key->rsa->n); 195 buffer_get_bignum(&e->input, challenge); 196 197 /* Only protocol 1.1 is supported */ 198 if (buffer_len(&e->input) == 0) 199 goto failure; 200 buffer_get(&e->input, session_id, 16); 201 response_type = buffer_get_int(&e->input); 202 if (response_type != 1) 203 goto failure; 204 205 id = lookup_identity(key, 1); 206 if (id != NULL) { 207 Key *private = id->key; 208 /* Decrypt the challenge using the private key. */ 209 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 210 goto failure; 211 212 /* The response is MD5 of decrypted challenge plus session id. */ 213 len = BN_num_bytes(challenge); 214 if (len <= 0 || len > 32) { 215 log("process_authentication_challenge: bad challenge length %d", len); 216 goto failure; 217 } 218 memset(buf, 0, 32); 219 BN_bn2bin(challenge, buf + 32 - len); 220 MD5_Init(&md); 221 MD5_Update(&md, buf, 32); 222 MD5_Update(&md, session_id, 16); 223 MD5_Final(mdbuf, &md); 224 225 /* Send the response. */ 226 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 227 for (i = 0; i < 16; i++) 228 buffer_put_char(&msg, mdbuf[i]); 229 goto send; 230 } 231 232 failure: 233 /* Unknown identity or protocol error. Send failure. */ 234 buffer_put_char(&msg, SSH_AGENT_FAILURE); 235 send: 236 buffer_put_int(&e->output, buffer_len(&msg)); 237 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 238 key_free(key); 239 BN_clear_free(challenge); 240 buffer_free(&msg); 241 } 242 243 /* ssh2 only */ 244 static void 245 process_sign_request2(SocketEntry *e) 246 { 247 extern int datafellows; 248 Key *key; 249 u_char *blob, *data, *signature = NULL; 250 u_int blen, dlen, slen = 0; 251 int flags; 252 Buffer msg; 253 int ok = -1; 254 255 datafellows = 0; 256 257 blob = buffer_get_string(&e->input, &blen); 258 data = buffer_get_string(&e->input, &dlen); 259 260 flags = buffer_get_int(&e->input); 261 if (flags & SSH_AGENT_OLD_SIGNATURE) 262 datafellows = SSH_BUG_SIGBLOB; 263 264 key = key_from_blob(blob, blen); 265 if (key != NULL) { 266 Identity *id = lookup_identity(key, 2); 267 if (id != NULL) 268 ok = key_sign(id->key, &signature, &slen, data, dlen); 269 } 270 key_free(key); 271 buffer_init(&msg); 272 if (ok == 0) { 273 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 274 buffer_put_string(&msg, signature, slen); 275 } else { 276 buffer_put_char(&msg, SSH_AGENT_FAILURE); 277 } 278 buffer_put_int(&e->output, buffer_len(&msg)); 279 buffer_append(&e->output, buffer_ptr(&msg), 280 buffer_len(&msg)); 281 buffer_free(&msg); 282 xfree(data); 283 xfree(blob); 284 if (signature != NULL) 285 xfree(signature); 286 } 287 288 /* shared */ 289 static void 290 process_remove_identity(SocketEntry *e, int version) 291 { 292 Key *key = NULL; 293 u_char *blob; 294 u_int blen; 295 u_int bits; 296 int success = 0; 297 298 switch (version) { 299 case 1: 300 key = key_new(KEY_RSA1); 301 bits = buffer_get_int(&e->input); 302 buffer_get_bignum(&e->input, key->rsa->e); 303 buffer_get_bignum(&e->input, key->rsa->n); 304 305 if (bits != key_size(key)) 306 log("Warning: identity keysize mismatch: actual %d, announced %d", 307 key_size(key), bits); 308 break; 309 case 2: 310 blob = buffer_get_string(&e->input, &blen); 311 key = key_from_blob(blob, blen); 312 xfree(blob); 313 break; 314 } 315 if (key != NULL) { 316 Identity *id = lookup_identity(key, version); 317 if (id != NULL) { 318 /* 319 * We have this key. Free the old key. Since we 320 * don\'t want to leave empty slots in the middle of 321 * the array, we actually free the key there and move 322 * all the entries between the empty slot and the end 323 * of the array. 324 */ 325 Idtab *tab = idtab_lookup(version); 326 if (tab->nentries < 1) 327 fatal("process_remove_identity: " 328 "internal error: tab->nentries %d", 329 tab->nentries); 330 TAILQ_REMOVE(&tab->idlist, id, next); 331 free_identity(id); 332 tab->nentries--; 333 success = 1; 334 } 335 key_free(key); 336 } 337 buffer_put_int(&e->output, 1); 338 buffer_put_char(&e->output, 339 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 340 } 341 342 static void 343 process_remove_all_identities(SocketEntry *e, int version) 344 { 345 Idtab *tab = idtab_lookup(version); 346 Identity *id; 347 348 /* Loop over all identities and clear the keys. */ 349 for (id = TAILQ_FIRST(&tab->idlist); id; 350 id = TAILQ_FIRST(&tab->idlist)) { 351 TAILQ_REMOVE(&tab->idlist, id, next); 352 free_identity(id); 353 } 354 355 /* Mark that there are no identities. */ 356 tab->nentries = 0; 357 358 /* Send success. */ 359 buffer_put_int(&e->output, 1); 360 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 361 return; 362 } 363 364 static void 365 process_add_identity(SocketEntry *e, int version) 366 { 367 Key *k = NULL; 368 char *type_name; 369 char *comment; 370 int type, success = 0; 371 Idtab *tab = idtab_lookup(version); 372 373 switch (version) { 374 case 1: 375 k = key_new_private(KEY_RSA1); 376 buffer_get_int(&e->input); /* ignored */ 377 buffer_get_bignum(&e->input, k->rsa->n); 378 buffer_get_bignum(&e->input, k->rsa->e); 379 buffer_get_bignum(&e->input, k->rsa->d); 380 buffer_get_bignum(&e->input, k->rsa->iqmp); 381 382 /* SSH and SSL have p and q swapped */ 383 buffer_get_bignum(&e->input, k->rsa->q); /* p */ 384 buffer_get_bignum(&e->input, k->rsa->p); /* q */ 385 386 /* Generate additional parameters */ 387 rsa_generate_additional_parameters(k->rsa); 388 break; 389 case 2: 390 type_name = buffer_get_string(&e->input, NULL); 391 type = key_type_from_name(type_name); 392 xfree(type_name); 393 switch (type) { 394 case KEY_DSA: 395 k = key_new_private(type); 396 buffer_get_bignum2(&e->input, k->dsa->p); 397 buffer_get_bignum2(&e->input, k->dsa->q); 398 buffer_get_bignum2(&e->input, k->dsa->g); 399 buffer_get_bignum2(&e->input, k->dsa->pub_key); 400 buffer_get_bignum2(&e->input, k->dsa->priv_key); 401 break; 402 case KEY_RSA: 403 k = key_new_private(type); 404 buffer_get_bignum2(&e->input, k->rsa->n); 405 buffer_get_bignum2(&e->input, k->rsa->e); 406 buffer_get_bignum2(&e->input, k->rsa->d); 407 buffer_get_bignum2(&e->input, k->rsa->iqmp); 408 buffer_get_bignum2(&e->input, k->rsa->p); 409 buffer_get_bignum2(&e->input, k->rsa->q); 410 411 /* Generate additional parameters */ 412 rsa_generate_additional_parameters(k->rsa); 413 break; 414 default: 415 buffer_clear(&e->input); 416 goto send; 417 } 418 break; 419 } 420 comment = buffer_get_string(&e->input, NULL); 421 if (k == NULL) { 422 xfree(comment); 423 goto send; 424 } 425 success = 1; 426 if (lookup_identity(k, version) == NULL) { 427 Identity *id = xmalloc(sizeof(Identity)); 428 id->key = k; 429 id->comment = comment; 430 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 431 /* Increment the number of identities. */ 432 tab->nentries++; 433 } else { 434 key_free(k); 435 xfree(comment); 436 } 437 send: 438 buffer_put_int(&e->output, 1); 439 buffer_put_char(&e->output, 440 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 441 } 442 443 444 #ifdef SMARTCARD 445 static void 446 process_add_smartcard_key (SocketEntry *e) 447 { 448 Idtab *tab; 449 Key *n = NULL, *k = NULL; 450 char *sc_reader_id = NULL; 451 int success = 0; 452 453 sc_reader_id = buffer_get_string(&e->input, NULL); 454 k = sc_get_key(sc_reader_id); 455 xfree(sc_reader_id); 456 457 if (k == NULL) { 458 error("sc_get_pubkey failed"); 459 goto send; 460 } 461 success = 1; 462 463 tab = idtab_lookup(1); 464 k->type = KEY_RSA1; 465 if (lookup_identity(k, 1) == NULL) { 466 Identity *id = xmalloc(sizeof(Identity)); 467 n = key_new(KEY_RSA1); 468 BN_copy(n->rsa->n, k->rsa->n); 469 BN_copy(n->rsa->e, k->rsa->e); 470 RSA_set_method(n->rsa, sc_get_engine()); 471 id->key = n; 472 id->comment = xstrdup("rsa1 smartcard"); 473 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 474 tab->nentries++; 475 } 476 k->type = KEY_RSA; 477 tab = idtab_lookup(2); 478 if (lookup_identity(k, 2) == NULL) { 479 Identity *id = xmalloc(sizeof(Identity)); 480 n = key_new(KEY_RSA); 481 BN_copy(n->rsa->n, k->rsa->n); 482 BN_copy(n->rsa->e, k->rsa->e); 483 RSA_set_method(n->rsa, sc_get_engine()); 484 id->key = n; 485 id->comment = xstrdup("rsa smartcard"); 486 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 487 tab->nentries++; 488 } 489 key_free(k); 490 send: 491 buffer_put_int(&e->output, 1); 492 buffer_put_char(&e->output, 493 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 494 } 495 496 static void 497 process_remove_smartcard_key(SocketEntry *e) 498 { 499 Key *k = NULL; 500 int success = 0; 501 char *sc_reader_id = NULL; 502 503 sc_reader_id = buffer_get_string(&e->input, NULL); 504 k = sc_get_key(sc_reader_id); 505 xfree(sc_reader_id); 506 507 if (k == NULL) { 508 error("sc_get_pubkey failed"); 509 } else { 510 Identity *id; 511 k->type = KEY_RSA1; 512 id = lookup_identity(k, 1); 513 if (id != NULL) { 514 Idtab *tab = idtab_lookup(1); 515 TAILQ_REMOVE(&tab->idlist, id, next); 516 free_identity(id); 517 tab->nentries--; 518 success = 1; 519 } 520 k->type = KEY_RSA; 521 id = lookup_identity(k, 2); 522 if (id != NULL) { 523 Idtab *tab = idtab_lookup(2); 524 TAILQ_REMOVE(&tab->idlist, id, next); 525 free_identity(id); 526 tab->nentries--; 527 success = 1; 528 } 529 key_free(k); 530 } 531 532 buffer_put_int(&e->output, 1); 533 buffer_put_char(&e->output, 534 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 535 } 536 #endif /* SMARTCARD */ 537 538 /* dispatch incoming messages */ 539 540 static void 541 process_message(SocketEntry *e) 542 { 543 u_int msg_len; 544 u_int type; 545 u_char *cp; 546 if (buffer_len(&e->input) < 5) 547 return; /* Incomplete message. */ 548 cp = buffer_ptr(&e->input); 549 msg_len = GET_32BIT(cp); 550 if (msg_len > 256 * 1024) { 551 shutdown(e->fd, SHUT_RDWR); 552 close(e->fd); 553 e->type = AUTH_UNUSED; 554 return; 555 } 556 if (buffer_len(&e->input) < msg_len + 4) 557 return; 558 buffer_consume(&e->input, 4); 559 type = buffer_get_char(&e->input); 560 561 debug("type %d", type); 562 switch (type) { 563 /* ssh1 */ 564 case SSH_AGENTC_RSA_CHALLENGE: 565 process_authentication_challenge1(e); 566 break; 567 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 568 process_request_identities(e, 1); 569 break; 570 case SSH_AGENTC_ADD_RSA_IDENTITY: 571 process_add_identity(e, 1); 572 break; 573 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 574 process_remove_identity(e, 1); 575 break; 576 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 577 process_remove_all_identities(e, 1); 578 break; 579 /* ssh2 */ 580 case SSH2_AGENTC_SIGN_REQUEST: 581 process_sign_request2(e); 582 break; 583 case SSH2_AGENTC_REQUEST_IDENTITIES: 584 process_request_identities(e, 2); 585 break; 586 case SSH2_AGENTC_ADD_IDENTITY: 587 process_add_identity(e, 2); 588 break; 589 case SSH2_AGENTC_REMOVE_IDENTITY: 590 process_remove_identity(e, 2); 591 break; 592 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 593 process_remove_all_identities(e, 2); 594 break; 595 #ifdef SMARTCARD 596 case SSH_AGENTC_ADD_SMARTCARD_KEY: 597 process_add_smartcard_key(e); 598 break; 599 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 600 process_remove_smartcard_key(e); 601 break; 602 #endif /* SMARTCARD */ 603 default: 604 /* Unknown message. Respond with failure. */ 605 error("Unknown message %d", type); 606 buffer_clear(&e->input); 607 buffer_put_int(&e->output, 1); 608 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 609 break; 610 } 611 } 612 613 static void 614 new_socket(sock_type type, int fd) 615 { 616 u_int i, old_alloc; 617 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) 618 error("fcntl O_NONBLOCK: %s", strerror(errno)); 619 620 if (fd > max_fd) 621 max_fd = fd; 622 623 for (i = 0; i < sockets_alloc; i++) 624 if (sockets[i].type == AUTH_UNUSED) { 625 sockets[i].fd = fd; 626 sockets[i].type = type; 627 buffer_init(&sockets[i].input); 628 buffer_init(&sockets[i].output); 629 return; 630 } 631 old_alloc = sockets_alloc; 632 sockets_alloc += 10; 633 if (sockets) 634 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); 635 else 636 sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); 637 for (i = old_alloc; i < sockets_alloc; i++) 638 sockets[i].type = AUTH_UNUSED; 639 sockets[old_alloc].type = type; 640 sockets[old_alloc].fd = fd; 641 buffer_init(&sockets[old_alloc].input); 642 buffer_init(&sockets[old_alloc].output); 643 } 644 645 static int 646 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp) 647 { 648 u_int i, sz; 649 int n = 0; 650 651 for (i = 0; i < sockets_alloc; i++) { 652 switch (sockets[i].type) { 653 case AUTH_SOCKET: 654 case AUTH_CONNECTION: 655 n = MAX(n, sockets[i].fd); 656 break; 657 case AUTH_UNUSED: 658 break; 659 default: 660 fatal("Unknown socket type %d", sockets[i].type); 661 break; 662 } 663 } 664 665 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 666 if (*fdrp == NULL || sz > *nallocp) { 667 if (*fdrp) 668 xfree(*fdrp); 669 if (*fdwp) 670 xfree(*fdwp); 671 *fdrp = xmalloc(sz); 672 *fdwp = xmalloc(sz); 673 *nallocp = sz; 674 } 675 if (n < *fdl) 676 debug("XXX shrink: %d < %d", n, *fdl); 677 *fdl = n; 678 memset(*fdrp, 0, sz); 679 memset(*fdwp, 0, sz); 680 681 for (i = 0; i < sockets_alloc; i++) { 682 switch (sockets[i].type) { 683 case AUTH_SOCKET: 684 case AUTH_CONNECTION: 685 FD_SET(sockets[i].fd, *fdrp); 686 if (buffer_len(&sockets[i].output) > 0) 687 FD_SET(sockets[i].fd, *fdwp); 688 break; 689 default: 690 break; 691 } 692 } 693 return (1); 694 } 695 696 static void 697 after_select(fd_set *readset, fd_set *writeset) 698 { 699 u_int i; 700 int len, sock; 701 socklen_t slen; 702 char buf[1024]; 703 struct sockaddr_un sunaddr; 704 705 for (i = 0; i < sockets_alloc; i++) 706 switch (sockets[i].type) { 707 case AUTH_UNUSED: 708 break; 709 case AUTH_SOCKET: 710 if (FD_ISSET(sockets[i].fd, readset)) { 711 slen = sizeof(sunaddr); 712 sock = accept(sockets[i].fd, 713 (struct sockaddr *) &sunaddr, &slen); 714 if (sock < 0) { 715 error("accept from AUTH_SOCKET: %s", 716 strerror(errno)); 717 break; 718 } 719 new_socket(AUTH_CONNECTION, sock); 720 } 721 break; 722 case AUTH_CONNECTION: 723 if (buffer_len(&sockets[i].output) > 0 && 724 FD_ISSET(sockets[i].fd, writeset)) { 725 do { 726 len = write(sockets[i].fd, 727 buffer_ptr(&sockets[i].output), 728 buffer_len(&sockets[i].output)); 729 if (len == -1 && (errno == EAGAIN || 730 errno == EINTR)) 731 continue; 732 break; 733 } while (1); 734 if (len <= 0) { 735 shutdown(sockets[i].fd, SHUT_RDWR); 736 close(sockets[i].fd); 737 sockets[i].type = AUTH_UNUSED; 738 buffer_free(&sockets[i].input); 739 buffer_free(&sockets[i].output); 740 break; 741 } 742 buffer_consume(&sockets[i].output, len); 743 } 744 if (FD_ISSET(sockets[i].fd, readset)) { 745 do { 746 len = read(sockets[i].fd, buf, sizeof(buf)); 747 if (len == -1 && (errno == EAGAIN || 748 errno == EINTR)) 749 continue; 750 break; 751 } while (1); 752 if (len <= 0) { 753 shutdown(sockets[i].fd, SHUT_RDWR); 754 close(sockets[i].fd); 755 sockets[i].type = AUTH_UNUSED; 756 buffer_free(&sockets[i].input); 757 buffer_free(&sockets[i].output); 758 break; 759 } 760 buffer_append(&sockets[i].input, buf, len); 761 process_message(&sockets[i]); 762 } 763 break; 764 default: 765 fatal("Unknown type %d", sockets[i].type); 766 } 767 } 768 769 static void 770 cleanup_socket(void *p) 771 { 772 if (socket_name[0]) 773 unlink(socket_name); 774 if (socket_dir[0]) 775 rmdir(socket_dir); 776 } 777 778 static void 779 cleanup_exit(int i) 780 { 781 cleanup_socket(NULL); 782 exit(i); 783 } 784 785 static void 786 cleanup_handler(int sig) 787 { 788 cleanup_socket(NULL); 789 _exit(2); 790 } 791 792 static void 793 check_parent_exists(int sig) 794 { 795 int save_errno = errno; 796 797 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 798 /* printf("Parent has died - Authentication agent exiting.\n"); */ 799 cleanup_handler(sig); /* safe */ 800 } 801 signal(SIGALRM, check_parent_exists); 802 alarm(10); 803 errno = save_errno; 804 } 805 806 static void 807 usage(void) 808 { 809 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n", 810 __progname); 811 fprintf(stderr, "Options:\n"); 812 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 813 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 814 fprintf(stderr, " -k Kill the current agent.\n"); 815 fprintf(stderr, " -d Debug mode.\n"); 816 exit(1); 817 } 818 819 int 820 main(int ac, char **av) 821 { 822 int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc; 823 struct sockaddr_un sunaddr; 824 struct rlimit rlim; 825 pid_t pid; 826 char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; 827 extern int optind; 828 fd_set *readsetp = NULL, *writesetp = NULL; 829 830 SSLeay_add_all_algorithms(); 831 832 while ((ch = getopt(ac, av, "cdks")) != -1) { 833 switch (ch) { 834 case 'c': 835 if (s_flag) 836 usage(); 837 c_flag++; 838 break; 839 case 'k': 840 k_flag++; 841 break; 842 case 's': 843 if (c_flag) 844 usage(); 845 s_flag++; 846 break; 847 case 'd': 848 if (d_flag) 849 usage(); 850 d_flag++; 851 break; 852 default: 853 usage(); 854 } 855 } 856 ac -= optind; 857 av += optind; 858 859 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 860 usage(); 861 862 if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) { 863 shell = getenv("SHELL"); 864 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 865 c_flag = 1; 866 } 867 if (k_flag) { 868 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 869 if (pidstr == NULL) { 870 fprintf(stderr, "%s not set, cannot kill agent\n", 871 SSH_AGENTPID_ENV_NAME); 872 exit(1); 873 } 874 pid = atoi(pidstr); 875 if (pid < 1) { 876 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 877 SSH_AGENTPID_ENV_NAME, pidstr); 878 exit(1); 879 } 880 if (kill(pid, SIGTERM) == -1) { 881 perror("kill"); 882 exit(1); 883 } 884 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 885 printf(format, SSH_AUTHSOCKET_ENV_NAME); 886 printf(format, SSH_AGENTPID_ENV_NAME); 887 printf("echo Agent pid %d killed;\n", pid); 888 exit(0); 889 } 890 parent_pid = getpid(); 891 892 /* Create private directory for agent socket */ 893 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); 894 if (mkdtemp(socket_dir) == NULL) { 895 perror("mkdtemp: private socket dir"); 896 exit(1); 897 } 898 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, 899 parent_pid); 900 901 /* 902 * Create socket early so it will exist before command gets run from 903 * the parent. 904 */ 905 sock = socket(AF_UNIX, SOCK_STREAM, 0); 906 if (sock < 0) { 907 perror("socket"); 908 cleanup_exit(1); 909 } 910 memset(&sunaddr, 0, sizeof(sunaddr)); 911 sunaddr.sun_family = AF_UNIX; 912 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 913 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { 914 perror("bind"); 915 cleanup_exit(1); 916 } 917 if (listen(sock, 5) < 0) { 918 perror("listen"); 919 cleanup_exit(1); 920 } 921 922 /* 923 * Fork, and have the parent execute the command, if any, or present 924 * the socket data. The child continues as the authentication agent. 925 */ 926 if (d_flag) { 927 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 928 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 929 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 930 SSH_AUTHSOCKET_ENV_NAME); 931 printf("echo Agent pid %d;\n", parent_pid); 932 goto skip; 933 } 934 pid = fork(); 935 if (pid == -1) { 936 perror("fork"); 937 cleanup_exit(1); 938 } 939 if (pid != 0) { /* Parent - execute the given command. */ 940 close(sock); 941 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid); 942 if (ac == 0) { 943 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 944 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 945 SSH_AUTHSOCKET_ENV_NAME); 946 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 947 SSH_AGENTPID_ENV_NAME); 948 printf("echo Agent pid %d;\n", pid); 949 exit(0); 950 } 951 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 952 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 953 perror("setenv"); 954 exit(1); 955 } 956 execvp(av[0], av); 957 perror(av[0]); 958 exit(1); 959 } 960 /* child */ 961 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 962 963 if (setsid() == -1) { 964 error("setsid: %s", strerror(errno)); 965 cleanup_exit(1); 966 } 967 968 (void)chdir("/"); 969 close(0); 970 close(1); 971 close(2); 972 973 /* deny core dumps, since memory contains unencrypted private keys */ 974 rlim.rlim_cur = rlim.rlim_max = 0; 975 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 976 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 977 cleanup_exit(1); 978 } 979 980 skip: 981 fatal_add_cleanup(cleanup_socket, NULL); 982 new_socket(AUTH_SOCKET, sock); 983 if (ac > 0) { 984 signal(SIGALRM, check_parent_exists); 985 alarm(10); 986 } 987 idtab_init(); 988 if (!d_flag) 989 signal(SIGINT, SIG_IGN); 990 signal(SIGPIPE, SIG_IGN); 991 signal(SIGHUP, cleanup_handler); 992 signal(SIGTERM, cleanup_handler); 993 nalloc = 0; 994 995 while (1) { 996 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc); 997 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) { 998 if (errno == EINTR) 999 continue; 1000 fatal("select: %s", strerror(errno)); 1001 } 1002 after_select(readsetp, writesetp); 1003 } 1004 /* NOTREACHED */ 1005 } 1006