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 "openbsd-compat/sys-queue.h" 38 RCSID("$OpenBSD: ssh-agent.c,v 1.120 2004/08/11 21:43:05 avsm Exp $"); 39 RCSID("$FreeBSD$"); 40 41 #include <openssl/evp.h> 42 #include <openssl/md5.h> 43 44 #include "ssh.h" 45 #include "rsa.h" 46 #include "buffer.h" 47 #include "bufaux.h" 48 #include "xmalloc.h" 49 #include "getput.h" 50 #include "key.h" 51 #include "authfd.h" 52 #include "compat.h" 53 #include "log.h" 54 #include "misc.h" 55 56 #ifdef SMARTCARD 57 #include "scard.h" 58 #endif 59 60 #if defined(HAVE_SYS_PRCTL_H) 61 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */ 62 #endif 63 64 typedef enum { 65 AUTH_UNUSED, 66 AUTH_SOCKET, 67 AUTH_CONNECTION 68 } sock_type; 69 70 typedef struct { 71 int fd; 72 sock_type type; 73 Buffer input; 74 Buffer output; 75 Buffer request; 76 } SocketEntry; 77 78 u_int sockets_alloc = 0; 79 SocketEntry *sockets = NULL; 80 81 typedef struct identity { 82 TAILQ_ENTRY(identity) next; 83 Key *key; 84 char *comment; 85 u_int death; 86 u_int confirm; 87 } Identity; 88 89 typedef struct { 90 int nentries; 91 TAILQ_HEAD(idqueue, identity) idlist; 92 } Idtab; 93 94 /* private key table, one per protocol version */ 95 Idtab idtable[3]; 96 97 int max_fd = 0; 98 99 /* pid of shell == parent of agent */ 100 pid_t parent_pid = -1; 101 102 /* pathname and directory for AUTH_SOCKET */ 103 char socket_name[1024]; 104 char socket_dir[1024]; 105 106 /* locking */ 107 int locked = 0; 108 char *lock_passwd = NULL; 109 110 extern char *__progname; 111 112 /* Default lifetime (0 == forever) */ 113 static int lifetime = 0; 114 115 static void 116 close_socket(SocketEntry *e) 117 { 118 close(e->fd); 119 e->fd = -1; 120 e->type = AUTH_UNUSED; 121 buffer_free(&e->input); 122 buffer_free(&e->output); 123 buffer_free(&e->request); 124 } 125 126 static void 127 idtab_init(void) 128 { 129 int i; 130 131 for (i = 0; i <=2; i++) { 132 TAILQ_INIT(&idtable[i].idlist); 133 idtable[i].nentries = 0; 134 } 135 } 136 137 /* return private key table for requested protocol version */ 138 static Idtab * 139 idtab_lookup(int version) 140 { 141 if (version < 1 || version > 2) 142 fatal("internal error, bad protocol version %d", version); 143 return &idtable[version]; 144 } 145 146 static void 147 free_identity(Identity *id) 148 { 149 key_free(id->key); 150 xfree(id->comment); 151 xfree(id); 152 } 153 154 /* return matching private key for given public key */ 155 static Identity * 156 lookup_identity(Key *key, int version) 157 { 158 Identity *id; 159 160 Idtab *tab = idtab_lookup(version); 161 TAILQ_FOREACH(id, &tab->idlist, next) { 162 if (key_equal(key, id->key)) 163 return (id); 164 } 165 return (NULL); 166 } 167 168 /* Check confirmation of keysign request */ 169 static int 170 confirm_key(Identity *id) 171 { 172 char *p, prompt[1024]; 173 int ret = -1; 174 175 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 176 snprintf(prompt, sizeof(prompt), "Allow use of key %s?\n" 177 "Key fingerprint %s.", id->comment, p); 178 xfree(p); 179 p = read_passphrase(prompt, RP_ALLOW_EOF); 180 if (p != NULL) { 181 /* 182 * Accept empty responses and responses consisting 183 * of the word "yes" as affirmative. 184 */ 185 if (*p == '\0' || *p == '\n' || strcasecmp(p, "yes") == 0) 186 ret = 0; 187 xfree(p); 188 } 189 return (ret); 190 } 191 192 /* send list of supported public keys to 'client' */ 193 static void 194 process_request_identities(SocketEntry *e, int version) 195 { 196 Idtab *tab = idtab_lookup(version); 197 Identity *id; 198 Buffer msg; 199 200 buffer_init(&msg); 201 buffer_put_char(&msg, (version == 1) ? 202 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 203 buffer_put_int(&msg, tab->nentries); 204 TAILQ_FOREACH(id, &tab->idlist, next) { 205 if (id->key->type == KEY_RSA1) { 206 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n)); 207 buffer_put_bignum(&msg, id->key->rsa->e); 208 buffer_put_bignum(&msg, id->key->rsa->n); 209 } else { 210 u_char *blob; 211 u_int blen; 212 key_to_blob(id->key, &blob, &blen); 213 buffer_put_string(&msg, blob, blen); 214 xfree(blob); 215 } 216 buffer_put_cstring(&msg, id->comment); 217 } 218 buffer_put_int(&e->output, buffer_len(&msg)); 219 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 220 buffer_free(&msg); 221 } 222 223 /* ssh1 only */ 224 static void 225 process_authentication_challenge1(SocketEntry *e) 226 { 227 u_char buf[32], mdbuf[16], session_id[16]; 228 u_int response_type; 229 BIGNUM *challenge; 230 Identity *id; 231 int i, len; 232 Buffer msg; 233 MD5_CTX md; 234 Key *key; 235 236 buffer_init(&msg); 237 key = key_new(KEY_RSA1); 238 if ((challenge = BN_new()) == NULL) 239 fatal("process_authentication_challenge1: BN_new failed"); 240 241 (void) buffer_get_int(&e->request); /* ignored */ 242 buffer_get_bignum(&e->request, key->rsa->e); 243 buffer_get_bignum(&e->request, key->rsa->n); 244 buffer_get_bignum(&e->request, challenge); 245 246 /* Only protocol 1.1 is supported */ 247 if (buffer_len(&e->request) == 0) 248 goto failure; 249 buffer_get(&e->request, session_id, 16); 250 response_type = buffer_get_int(&e->request); 251 if (response_type != 1) 252 goto failure; 253 254 id = lookup_identity(key, 1); 255 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) { 256 Key *private = id->key; 257 /* Decrypt the challenge using the private key. */ 258 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0) 259 goto failure; 260 261 /* The response is MD5 of decrypted challenge plus session id. */ 262 len = BN_num_bytes(challenge); 263 if (len <= 0 || len > 32) { 264 logit("process_authentication_challenge: bad challenge length %d", len); 265 goto failure; 266 } 267 memset(buf, 0, 32); 268 BN_bn2bin(challenge, buf + 32 - len); 269 MD5_Init(&md); 270 MD5_Update(&md, buf, 32); 271 MD5_Update(&md, session_id, 16); 272 MD5_Final(mdbuf, &md); 273 274 /* Send the response. */ 275 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 276 for (i = 0; i < 16; i++) 277 buffer_put_char(&msg, mdbuf[i]); 278 goto send; 279 } 280 281 failure: 282 /* Unknown identity or protocol error. Send failure. */ 283 buffer_put_char(&msg, SSH_AGENT_FAILURE); 284 send: 285 buffer_put_int(&e->output, buffer_len(&msg)); 286 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 287 key_free(key); 288 BN_clear_free(challenge); 289 buffer_free(&msg); 290 } 291 292 /* ssh2 only */ 293 static void 294 process_sign_request2(SocketEntry *e) 295 { 296 u_char *blob, *data, *signature = NULL; 297 u_int blen, dlen, slen = 0; 298 extern int datafellows; 299 int ok = -1, flags; 300 Buffer msg; 301 Key *key; 302 303 datafellows = 0; 304 305 blob = buffer_get_string(&e->request, &blen); 306 data = buffer_get_string(&e->request, &dlen); 307 308 flags = buffer_get_int(&e->request); 309 if (flags & SSH_AGENT_OLD_SIGNATURE) 310 datafellows = SSH_BUG_SIGBLOB; 311 312 key = key_from_blob(blob, blen); 313 if (key != NULL) { 314 Identity *id = lookup_identity(key, 2); 315 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) 316 ok = key_sign(id->key, &signature, &slen, data, dlen); 317 } 318 key_free(key); 319 buffer_init(&msg); 320 if (ok == 0) { 321 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); 322 buffer_put_string(&msg, signature, slen); 323 } else { 324 buffer_put_char(&msg, SSH_AGENT_FAILURE); 325 } 326 buffer_put_int(&e->output, buffer_len(&msg)); 327 buffer_append(&e->output, buffer_ptr(&msg), 328 buffer_len(&msg)); 329 buffer_free(&msg); 330 xfree(data); 331 xfree(blob); 332 if (signature != NULL) 333 xfree(signature); 334 } 335 336 /* shared */ 337 static void 338 process_remove_identity(SocketEntry *e, int version) 339 { 340 u_int blen, bits; 341 int success = 0; 342 Key *key = NULL; 343 u_char *blob; 344 345 switch (version) { 346 case 1: 347 key = key_new(KEY_RSA1); 348 bits = buffer_get_int(&e->request); 349 buffer_get_bignum(&e->request, key->rsa->e); 350 buffer_get_bignum(&e->request, key->rsa->n); 351 352 if (bits != key_size(key)) 353 logit("Warning: identity keysize mismatch: actual %u, announced %u", 354 key_size(key), bits); 355 break; 356 case 2: 357 blob = buffer_get_string(&e->request, &blen); 358 key = key_from_blob(blob, blen); 359 xfree(blob); 360 break; 361 } 362 if (key != NULL) { 363 Identity *id = lookup_identity(key, version); 364 if (id != NULL) { 365 /* 366 * We have this key. Free the old key. Since we 367 * don\'t want to leave empty slots in the middle of 368 * the array, we actually free the key there and move 369 * all the entries between the empty slot and the end 370 * of the array. 371 */ 372 Idtab *tab = idtab_lookup(version); 373 if (tab->nentries < 1) 374 fatal("process_remove_identity: " 375 "internal error: tab->nentries %d", 376 tab->nentries); 377 TAILQ_REMOVE(&tab->idlist, id, next); 378 free_identity(id); 379 tab->nentries--; 380 success = 1; 381 } 382 key_free(key); 383 } 384 buffer_put_int(&e->output, 1); 385 buffer_put_char(&e->output, 386 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 387 } 388 389 static void 390 process_remove_all_identities(SocketEntry *e, int version) 391 { 392 Idtab *tab = idtab_lookup(version); 393 Identity *id; 394 395 /* Loop over all identities and clear the keys. */ 396 for (id = TAILQ_FIRST(&tab->idlist); id; 397 id = TAILQ_FIRST(&tab->idlist)) { 398 TAILQ_REMOVE(&tab->idlist, id, next); 399 free_identity(id); 400 } 401 402 /* Mark that there are no identities. */ 403 tab->nentries = 0; 404 405 /* Send success. */ 406 buffer_put_int(&e->output, 1); 407 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 408 } 409 410 static void 411 reaper(void) 412 { 413 u_int now = time(NULL); 414 Identity *id, *nxt; 415 int version; 416 Idtab *tab; 417 418 for (version = 1; version < 3; version++) { 419 tab = idtab_lookup(version); 420 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) { 421 nxt = TAILQ_NEXT(id, next); 422 if (id->death != 0 && now >= id->death) { 423 TAILQ_REMOVE(&tab->idlist, id, next); 424 free_identity(id); 425 tab->nentries--; 426 } 427 } 428 } 429 } 430 431 static void 432 process_add_identity(SocketEntry *e, int version) 433 { 434 Idtab *tab = idtab_lookup(version); 435 int type, success = 0, death = 0, confirm = 0; 436 char *type_name, *comment; 437 Key *k = NULL; 438 439 switch (version) { 440 case 1: 441 k = key_new_private(KEY_RSA1); 442 (void) buffer_get_int(&e->request); /* ignored */ 443 buffer_get_bignum(&e->request, k->rsa->n); 444 buffer_get_bignum(&e->request, k->rsa->e); 445 buffer_get_bignum(&e->request, k->rsa->d); 446 buffer_get_bignum(&e->request, k->rsa->iqmp); 447 448 /* SSH and SSL have p and q swapped */ 449 buffer_get_bignum(&e->request, k->rsa->q); /* p */ 450 buffer_get_bignum(&e->request, k->rsa->p); /* q */ 451 452 /* Generate additional parameters */ 453 rsa_generate_additional_parameters(k->rsa); 454 break; 455 case 2: 456 type_name = buffer_get_string(&e->request, NULL); 457 type = key_type_from_name(type_name); 458 xfree(type_name); 459 switch (type) { 460 case KEY_DSA: 461 k = key_new_private(type); 462 buffer_get_bignum2(&e->request, k->dsa->p); 463 buffer_get_bignum2(&e->request, k->dsa->q); 464 buffer_get_bignum2(&e->request, k->dsa->g); 465 buffer_get_bignum2(&e->request, k->dsa->pub_key); 466 buffer_get_bignum2(&e->request, k->dsa->priv_key); 467 break; 468 case KEY_RSA: 469 k = key_new_private(type); 470 buffer_get_bignum2(&e->request, k->rsa->n); 471 buffer_get_bignum2(&e->request, k->rsa->e); 472 buffer_get_bignum2(&e->request, k->rsa->d); 473 buffer_get_bignum2(&e->request, k->rsa->iqmp); 474 buffer_get_bignum2(&e->request, k->rsa->p); 475 buffer_get_bignum2(&e->request, k->rsa->q); 476 477 /* Generate additional parameters */ 478 rsa_generate_additional_parameters(k->rsa); 479 break; 480 default: 481 buffer_clear(&e->request); 482 goto send; 483 } 484 break; 485 } 486 /* enable blinding */ 487 switch (k->type) { 488 case KEY_RSA: 489 case KEY_RSA1: 490 if (RSA_blinding_on(k->rsa, NULL) != 1) { 491 error("process_add_identity: RSA_blinding_on failed"); 492 key_free(k); 493 goto send; 494 } 495 break; 496 } 497 comment = buffer_get_string(&e->request, NULL); 498 if (k == NULL) { 499 xfree(comment); 500 goto send; 501 } 502 success = 1; 503 while (buffer_len(&e->request)) { 504 switch (buffer_get_char(&e->request)) { 505 case SSH_AGENT_CONSTRAIN_LIFETIME: 506 death = time(NULL) + buffer_get_int(&e->request); 507 break; 508 case SSH_AGENT_CONSTRAIN_CONFIRM: 509 confirm = 1; 510 break; 511 default: 512 break; 513 } 514 } 515 if (lifetime && !death) 516 death = time(NULL) + lifetime; 517 if (lookup_identity(k, version) == NULL) { 518 Identity *id = xmalloc(sizeof(Identity)); 519 id->key = k; 520 id->comment = comment; 521 id->death = death; 522 id->confirm = confirm; 523 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 524 /* Increment the number of identities. */ 525 tab->nentries++; 526 } else { 527 key_free(k); 528 xfree(comment); 529 } 530 send: 531 buffer_put_int(&e->output, 1); 532 buffer_put_char(&e->output, 533 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 534 } 535 536 /* XXX todo: encrypt sensitive data with passphrase */ 537 static void 538 process_lock_agent(SocketEntry *e, int lock) 539 { 540 int success = 0; 541 char *passwd; 542 543 passwd = buffer_get_string(&e->request, NULL); 544 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { 545 locked = 0; 546 memset(lock_passwd, 0, strlen(lock_passwd)); 547 xfree(lock_passwd); 548 lock_passwd = NULL; 549 success = 1; 550 } else if (!locked && lock) { 551 locked = 1; 552 lock_passwd = xstrdup(passwd); 553 success = 1; 554 } 555 memset(passwd, 0, strlen(passwd)); 556 xfree(passwd); 557 558 buffer_put_int(&e->output, 1); 559 buffer_put_char(&e->output, 560 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 561 } 562 563 static void 564 no_identities(SocketEntry *e, u_int type) 565 { 566 Buffer msg; 567 568 buffer_init(&msg); 569 buffer_put_char(&msg, 570 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ? 571 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER); 572 buffer_put_int(&msg, 0); 573 buffer_put_int(&e->output, buffer_len(&msg)); 574 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 575 buffer_free(&msg); 576 } 577 578 #ifdef SMARTCARD 579 static void 580 process_add_smartcard_key (SocketEntry *e) 581 { 582 char *sc_reader_id = NULL, *pin; 583 int i, version, success = 0, death = 0, confirm = 0; 584 Key **keys, *k; 585 Identity *id; 586 Idtab *tab; 587 588 sc_reader_id = buffer_get_string(&e->request, NULL); 589 pin = buffer_get_string(&e->request, NULL); 590 591 while (buffer_len(&e->request)) { 592 switch (buffer_get_char(&e->request)) { 593 case SSH_AGENT_CONSTRAIN_LIFETIME: 594 death = time(NULL) + buffer_get_int(&e->request); 595 break; 596 case SSH_AGENT_CONSTRAIN_CONFIRM: 597 confirm = 1; 598 break; 599 default: 600 break; 601 } 602 } 603 if (lifetime && !death) 604 death = time(NULL) + lifetime; 605 606 keys = sc_get_keys(sc_reader_id, pin); 607 xfree(sc_reader_id); 608 xfree(pin); 609 610 if (keys == NULL || keys[0] == NULL) { 611 error("sc_get_keys failed"); 612 goto send; 613 } 614 for (i = 0; keys[i] != NULL; i++) { 615 k = keys[i]; 616 version = k->type == KEY_RSA1 ? 1 : 2; 617 tab = idtab_lookup(version); 618 if (lookup_identity(k, version) == NULL) { 619 id = xmalloc(sizeof(Identity)); 620 id->key = k; 621 id->comment = sc_get_key_label(k); 622 id->death = death; 623 id->confirm = confirm; 624 TAILQ_INSERT_TAIL(&tab->idlist, id, next); 625 tab->nentries++; 626 success = 1; 627 } else { 628 key_free(k); 629 } 630 keys[i] = NULL; 631 } 632 xfree(keys); 633 send: 634 buffer_put_int(&e->output, 1); 635 buffer_put_char(&e->output, 636 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 637 } 638 639 static void 640 process_remove_smartcard_key(SocketEntry *e) 641 { 642 char *sc_reader_id = NULL, *pin; 643 int i, version, success = 0; 644 Key **keys, *k = NULL; 645 Identity *id; 646 Idtab *tab; 647 648 sc_reader_id = buffer_get_string(&e->request, NULL); 649 pin = buffer_get_string(&e->request, NULL); 650 keys = sc_get_keys(sc_reader_id, pin); 651 xfree(sc_reader_id); 652 xfree(pin); 653 654 if (keys == NULL || keys[0] == NULL) { 655 error("sc_get_keys failed"); 656 goto send; 657 } 658 for (i = 0; keys[i] != NULL; i++) { 659 k = keys[i]; 660 version = k->type == KEY_RSA1 ? 1 : 2; 661 if ((id = lookup_identity(k, version)) != NULL) { 662 tab = idtab_lookup(version); 663 TAILQ_REMOVE(&tab->idlist, id, next); 664 tab->nentries--; 665 free_identity(id); 666 success = 1; 667 } 668 key_free(k); 669 keys[i] = NULL; 670 } 671 xfree(keys); 672 send: 673 buffer_put_int(&e->output, 1); 674 buffer_put_char(&e->output, 675 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE); 676 } 677 #endif /* SMARTCARD */ 678 679 /* dispatch incoming messages */ 680 681 static void 682 process_message(SocketEntry *e) 683 { 684 u_int msg_len, type; 685 u_char *cp; 686 687 /* kill dead keys */ 688 reaper(); 689 690 if (buffer_len(&e->input) < 5) 691 return; /* Incomplete message. */ 692 cp = buffer_ptr(&e->input); 693 msg_len = GET_32BIT(cp); 694 if (msg_len > 256 * 1024) { 695 close_socket(e); 696 return; 697 } 698 if (buffer_len(&e->input) < msg_len + 4) 699 return; 700 701 /* move the current input to e->request */ 702 buffer_consume(&e->input, 4); 703 buffer_clear(&e->request); 704 buffer_append(&e->request, buffer_ptr(&e->input), msg_len); 705 buffer_consume(&e->input, msg_len); 706 type = buffer_get_char(&e->request); 707 708 /* check wheter agent is locked */ 709 if (locked && type != SSH_AGENTC_UNLOCK) { 710 buffer_clear(&e->request); 711 switch (type) { 712 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 713 case SSH2_AGENTC_REQUEST_IDENTITIES: 714 /* send empty lists */ 715 no_identities(e, type); 716 break; 717 default: 718 /* send a fail message for all other request types */ 719 buffer_put_int(&e->output, 1); 720 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 721 } 722 return; 723 } 724 725 debug("type %d", type); 726 switch (type) { 727 case SSH_AGENTC_LOCK: 728 case SSH_AGENTC_UNLOCK: 729 process_lock_agent(e, type == SSH_AGENTC_LOCK); 730 break; 731 /* ssh1 */ 732 case SSH_AGENTC_RSA_CHALLENGE: 733 process_authentication_challenge1(e); 734 break; 735 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 736 process_request_identities(e, 1); 737 break; 738 case SSH_AGENTC_ADD_RSA_IDENTITY: 739 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED: 740 process_add_identity(e, 1); 741 break; 742 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 743 process_remove_identity(e, 1); 744 break; 745 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 746 process_remove_all_identities(e, 1); 747 break; 748 /* ssh2 */ 749 case SSH2_AGENTC_SIGN_REQUEST: 750 process_sign_request2(e); 751 break; 752 case SSH2_AGENTC_REQUEST_IDENTITIES: 753 process_request_identities(e, 2); 754 break; 755 case SSH2_AGENTC_ADD_IDENTITY: 756 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 757 process_add_identity(e, 2); 758 break; 759 case SSH2_AGENTC_REMOVE_IDENTITY: 760 process_remove_identity(e, 2); 761 break; 762 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 763 process_remove_all_identities(e, 2); 764 break; 765 #ifdef SMARTCARD 766 case SSH_AGENTC_ADD_SMARTCARD_KEY: 767 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 768 process_add_smartcard_key(e); 769 break; 770 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 771 process_remove_smartcard_key(e); 772 break; 773 #endif /* SMARTCARD */ 774 default: 775 /* Unknown message. Respond with failure. */ 776 error("Unknown message %d", type); 777 buffer_clear(&e->request); 778 buffer_put_int(&e->output, 1); 779 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 780 break; 781 } 782 } 783 784 static void 785 new_socket(sock_type type, int fd) 786 { 787 u_int i, old_alloc, new_alloc; 788 789 set_nonblock(fd); 790 791 if (fd > max_fd) 792 max_fd = fd; 793 794 for (i = 0; i < sockets_alloc; i++) 795 if (sockets[i].type == AUTH_UNUSED) { 796 sockets[i].fd = fd; 797 buffer_init(&sockets[i].input); 798 buffer_init(&sockets[i].output); 799 buffer_init(&sockets[i].request); 800 sockets[i].type = type; 801 return; 802 } 803 old_alloc = sockets_alloc; 804 new_alloc = sockets_alloc + 10; 805 if (sockets) 806 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0])); 807 else 808 sockets = xmalloc(new_alloc * sizeof(sockets[0])); 809 for (i = old_alloc; i < new_alloc; i++) 810 sockets[i].type = AUTH_UNUSED; 811 sockets_alloc = new_alloc; 812 sockets[old_alloc].fd = fd; 813 buffer_init(&sockets[old_alloc].input); 814 buffer_init(&sockets[old_alloc].output); 815 buffer_init(&sockets[old_alloc].request); 816 sockets[old_alloc].type = type; 817 } 818 819 static int 820 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp) 821 { 822 u_int i, sz; 823 int n = 0; 824 825 for (i = 0; i < sockets_alloc; i++) { 826 switch (sockets[i].type) { 827 case AUTH_SOCKET: 828 case AUTH_CONNECTION: 829 n = MAX(n, sockets[i].fd); 830 break; 831 case AUTH_UNUSED: 832 break; 833 default: 834 fatal("Unknown socket type %d", sockets[i].type); 835 break; 836 } 837 } 838 839 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); 840 if (*fdrp == NULL || sz > *nallocp) { 841 if (*fdrp) 842 xfree(*fdrp); 843 if (*fdwp) 844 xfree(*fdwp); 845 *fdrp = xmalloc(sz); 846 *fdwp = xmalloc(sz); 847 *nallocp = sz; 848 } 849 if (n < *fdl) 850 debug("XXX shrink: %d < %d", n, *fdl); 851 *fdl = n; 852 memset(*fdrp, 0, sz); 853 memset(*fdwp, 0, sz); 854 855 for (i = 0; i < sockets_alloc; i++) { 856 switch (sockets[i].type) { 857 case AUTH_SOCKET: 858 case AUTH_CONNECTION: 859 FD_SET(sockets[i].fd, *fdrp); 860 if (buffer_len(&sockets[i].output) > 0) 861 FD_SET(sockets[i].fd, *fdwp); 862 break; 863 default: 864 break; 865 } 866 } 867 return (1); 868 } 869 870 static void 871 after_select(fd_set *readset, fd_set *writeset) 872 { 873 struct sockaddr_un sunaddr; 874 socklen_t slen; 875 char buf[1024]; 876 int len, sock; 877 u_int i; 878 uid_t euid; 879 gid_t egid; 880 881 for (i = 0; i < sockets_alloc; i++) 882 switch (sockets[i].type) { 883 case AUTH_UNUSED: 884 break; 885 case AUTH_SOCKET: 886 if (FD_ISSET(sockets[i].fd, readset)) { 887 slen = sizeof(sunaddr); 888 sock = accept(sockets[i].fd, 889 (struct sockaddr *) &sunaddr, &slen); 890 if (sock < 0) { 891 error("accept from AUTH_SOCKET: %s", 892 strerror(errno)); 893 break; 894 } 895 if (getpeereid(sock, &euid, &egid) < 0) { 896 error("getpeereid %d failed: %s", 897 sock, strerror(errno)); 898 close(sock); 899 break; 900 } 901 if ((euid != 0) && (getuid() != euid)) { 902 error("uid mismatch: " 903 "peer euid %u != uid %u", 904 (u_int) euid, (u_int) getuid()); 905 close(sock); 906 break; 907 } 908 new_socket(AUTH_CONNECTION, sock); 909 } 910 break; 911 case AUTH_CONNECTION: 912 if (buffer_len(&sockets[i].output) > 0 && 913 FD_ISSET(sockets[i].fd, writeset)) { 914 do { 915 len = write(sockets[i].fd, 916 buffer_ptr(&sockets[i].output), 917 buffer_len(&sockets[i].output)); 918 if (len == -1 && (errno == EAGAIN || 919 errno == EINTR)) 920 continue; 921 break; 922 } while (1); 923 if (len <= 0) { 924 close_socket(&sockets[i]); 925 break; 926 } 927 buffer_consume(&sockets[i].output, len); 928 } 929 if (FD_ISSET(sockets[i].fd, readset)) { 930 do { 931 len = read(sockets[i].fd, buf, sizeof(buf)); 932 if (len == -1 && (errno == EAGAIN || 933 errno == EINTR)) 934 continue; 935 break; 936 } while (1); 937 if (len <= 0) { 938 close_socket(&sockets[i]); 939 break; 940 } 941 buffer_append(&sockets[i].input, buf, len); 942 process_message(&sockets[i]); 943 } 944 break; 945 default: 946 fatal("Unknown type %d", sockets[i].type); 947 } 948 } 949 950 static void 951 cleanup_socket(void) 952 { 953 if (socket_name[0]) 954 unlink(socket_name); 955 if (socket_dir[0]) 956 rmdir(socket_dir); 957 } 958 959 void 960 cleanup_exit(int i) 961 { 962 cleanup_socket(); 963 _exit(i); 964 } 965 966 static void 967 cleanup_handler(int sig) 968 { 969 cleanup_socket(); 970 _exit(2); 971 } 972 973 static void 974 check_parent_exists(int sig) 975 { 976 int save_errno = errno; 977 978 if (parent_pid != -1 && kill(parent_pid, 0) < 0) { 979 /* printf("Parent has died - Authentication agent exiting.\n"); */ 980 cleanup_handler(sig); /* safe */ 981 } 982 mysignal(SIGALRM, check_parent_exists); 983 alarm(10); 984 errno = save_errno; 985 } 986 987 static void 988 usage(void) 989 { 990 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n", 991 __progname); 992 fprintf(stderr, "Options:\n"); 993 fprintf(stderr, " -c Generate C-shell commands on stdout.\n"); 994 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n"); 995 fprintf(stderr, " -k Kill the current agent.\n"); 996 fprintf(stderr, " -d Debug mode.\n"); 997 fprintf(stderr, " -a socket Bind agent socket to given name.\n"); 998 fprintf(stderr, " -t life Default identity lifetime (seconds).\n"); 999 exit(1); 1000 } 1001 1002 int 1003 main(int ac, char **av) 1004 { 1005 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0; 1006 int sock, fd, ch; 1007 u_int nalloc; 1008 char *shell, *format, *pidstr, *agentsocket = NULL; 1009 fd_set *readsetp = NULL, *writesetp = NULL; 1010 struct sockaddr_un sunaddr; 1011 #ifdef HAVE_SETRLIMIT 1012 struct rlimit rlim; 1013 #endif 1014 #ifdef HAVE_CYGWIN 1015 int prev_mask; 1016 #endif 1017 extern int optind; 1018 extern char *optarg; 1019 pid_t pid; 1020 char pidstrbuf[1 + 3 * sizeof pid]; 1021 1022 /* drop */ 1023 setegid(getgid()); 1024 setgid(getgid()); 1025 setuid(geteuid()); 1026 1027 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) 1028 /* Disable ptrace on Linux without sgid bit */ 1029 prctl(PR_SET_DUMPABLE, 0); 1030 #endif 1031 1032 SSLeay_add_all_algorithms(); 1033 1034 __progname = ssh_get_progname(av[0]); 1035 init_rng(); 1036 seed_rng(); 1037 1038 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) { 1039 switch (ch) { 1040 case 'c': 1041 if (s_flag) 1042 usage(); 1043 c_flag++; 1044 break; 1045 case 'k': 1046 k_flag++; 1047 break; 1048 case 's': 1049 if (c_flag) 1050 usage(); 1051 s_flag++; 1052 break; 1053 case 'd': 1054 if (d_flag) 1055 usage(); 1056 d_flag++; 1057 break; 1058 case 'a': 1059 agentsocket = optarg; 1060 break; 1061 case 't': 1062 if ((lifetime = convtime(optarg)) == -1) { 1063 fprintf(stderr, "Invalid lifetime\n"); 1064 usage(); 1065 } 1066 break; 1067 default: 1068 usage(); 1069 } 1070 } 1071 ac -= optind; 1072 av += optind; 1073 1074 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag)) 1075 usage(); 1076 1077 if (ac == 0 && !c_flag && !s_flag) { 1078 shell = getenv("SHELL"); 1079 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 1080 c_flag = 1; 1081 } 1082 if (k_flag) { 1083 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1084 if (pidstr == NULL) { 1085 fprintf(stderr, "%s not set, cannot kill agent\n", 1086 SSH_AGENTPID_ENV_NAME); 1087 exit(1); 1088 } 1089 pid = atoi(pidstr); 1090 if (pid < 1) { 1091 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 1092 SSH_AGENTPID_ENV_NAME, pidstr); 1093 exit(1); 1094 } 1095 if (kill(pid, SIGTERM) == -1) { 1096 perror("kill"); 1097 exit(1); 1098 } 1099 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1100 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1101 printf(format, SSH_AGENTPID_ENV_NAME); 1102 printf("echo Agent pid %ld killed;\n", (long)pid); 1103 exit(0); 1104 } 1105 parent_pid = getpid(); 1106 1107 if (agentsocket == NULL) { 1108 /* Create private directory for agent socket */ 1109 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir); 1110 if (mkdtemp(socket_dir) == NULL) { 1111 perror("mkdtemp: private socket dir"); 1112 exit(1); 1113 } 1114 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1115 (long)parent_pid); 1116 } else { 1117 /* Try to use specified agent socket */ 1118 socket_dir[0] = '\0'; 1119 strlcpy(socket_name, agentsocket, sizeof socket_name); 1120 } 1121 1122 /* 1123 * Create socket early so it will exist before command gets run from 1124 * the parent. 1125 */ 1126 sock = socket(AF_UNIX, SOCK_STREAM, 0); 1127 if (sock < 0) { 1128 perror("socket"); 1129 cleanup_exit(1); 1130 } 1131 memset(&sunaddr, 0, sizeof(sunaddr)); 1132 sunaddr.sun_family = AF_UNIX; 1133 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 1134 #ifdef HAVE_CYGWIN 1135 prev_mask = umask(0177); 1136 #endif 1137 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { 1138 perror("bind"); 1139 #ifdef HAVE_CYGWIN 1140 umask(prev_mask); 1141 #endif 1142 cleanup_exit(1); 1143 } 1144 #ifdef HAVE_CYGWIN 1145 umask(prev_mask); 1146 #endif 1147 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 1148 perror("listen"); 1149 cleanup_exit(1); 1150 } 1151 1152 /* 1153 * Fork, and have the parent execute the command, if any, or present 1154 * the socket data. The child continues as the authentication agent. 1155 */ 1156 if (d_flag) { 1157 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1); 1158 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1159 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1160 SSH_AUTHSOCKET_ENV_NAME); 1161 printf("echo Agent pid %ld;\n", (long)parent_pid); 1162 goto skip; 1163 } 1164 pid = fork(); 1165 if (pid == -1) { 1166 perror("fork"); 1167 cleanup_exit(1); 1168 } 1169 if (pid != 0) { /* Parent - execute the given command. */ 1170 close(sock); 1171 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1172 if (ac == 0) { 1173 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1174 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1175 SSH_AUTHSOCKET_ENV_NAME); 1176 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1177 SSH_AGENTPID_ENV_NAME); 1178 printf("echo Agent pid %ld;\n", (long)pid); 1179 exit(0); 1180 } 1181 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1182 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1183 perror("setenv"); 1184 exit(1); 1185 } 1186 execvp(av[0], av); 1187 perror(av[0]); 1188 exit(1); 1189 } 1190 /* child */ 1191 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1192 1193 if (setsid() == -1) { 1194 error("setsid: %s", strerror(errno)); 1195 cleanup_exit(1); 1196 } 1197 1198 (void)chdir("/"); 1199 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1200 /* XXX might close listen socket */ 1201 (void)dup2(fd, STDIN_FILENO); 1202 (void)dup2(fd, STDOUT_FILENO); 1203 (void)dup2(fd, STDERR_FILENO); 1204 if (fd > 2) 1205 close(fd); 1206 } 1207 1208 #ifdef HAVE_SETRLIMIT 1209 /* deny core dumps, since memory contains unencrypted private keys */ 1210 rlim.rlim_cur = rlim.rlim_max = 0; 1211 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1212 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1213 cleanup_exit(1); 1214 } 1215 #endif 1216 1217 skip: 1218 new_socket(AUTH_SOCKET, sock); 1219 if (ac > 0) { 1220 mysignal(SIGALRM, check_parent_exists); 1221 alarm(10); 1222 } 1223 idtab_init(); 1224 if (!d_flag) 1225 signal(SIGINT, SIG_IGN); 1226 signal(SIGPIPE, SIG_IGN); 1227 signal(SIGHUP, cleanup_handler); 1228 signal(SIGTERM, cleanup_handler); 1229 nalloc = 0; 1230 1231 while (1) { 1232 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc); 1233 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) { 1234 if (errno == EINTR) 1235 continue; 1236 fatal("select: %s", strerror(errno)); 1237 } 1238 after_select(readsetp, writesetp); 1239 } 1240 /* NOTREACHED */ 1241 } 1242