25 26typedef struct { 27 int fd; 28 enum { 29 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION 30 } type; 31 Buffer input; 32 Buffer output; 33} SocketEntry; 34 35unsigned int sockets_alloc = 0; 36SocketEntry *sockets = NULL; 37 38typedef struct { 39 RSA *key; 40 char *comment; 41} Identity; 42 43unsigned int num_identities = 0; 44Identity *identities = NULL; 45 46int max_fd = 0; 47 48/* pid of shell == parent of agent */ 49int parent_pid = -1; 50 51/* pathname and directory for AUTH_SOCKET */ 52char socket_name[1024]; 53char socket_dir[1024]; 54 55extern char *__progname; 56 57void 58process_request_identity(SocketEntry *e) 59{ 60 Buffer msg; 61 int i; 62 63 buffer_init(&msg); 64 buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER); 65 buffer_put_int(&msg, num_identities); 66 for (i = 0; i < num_identities; i++) { 67 buffer_put_int(&msg, BN_num_bits(identities[i].key->n)); 68 buffer_put_bignum(&msg, identities[i].key->e); 69 buffer_put_bignum(&msg, identities[i].key->n); 70 buffer_put_string(&msg, identities[i].comment, 71 strlen(identities[i].comment)); 72 } 73 buffer_put_int(&e->output, buffer_len(&msg)); 74 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 75 buffer_free(&msg); 76} 77 78void 79process_authentication_challenge(SocketEntry *e) 80{ 81 int i, pub_bits, len; 82 BIGNUM *pub_e, *pub_n, *challenge; 83 Buffer msg; 84 MD5_CTX md; 85 unsigned char buf[32], mdbuf[16], session_id[16]; 86 unsigned int response_type; 87 88 buffer_init(&msg); 89 pub_e = BN_new(); 90 pub_n = BN_new(); 91 challenge = BN_new(); 92 pub_bits = buffer_get_int(&e->input); 93 buffer_get_bignum(&e->input, pub_e); 94 buffer_get_bignum(&e->input, pub_n); 95 buffer_get_bignum(&e->input, challenge); 96 if (buffer_len(&e->input) == 0) { 97 /* Compatibility code for old servers. */ 98 memset(session_id, 0, 16); 99 response_type = 0; 100 } else { 101 /* New code. */ 102 buffer_get(&e->input, (char *) session_id, 16); 103 response_type = buffer_get_int(&e->input); 104 } 105 for (i = 0; i < num_identities; i++) 106 if (pub_bits == BN_num_bits(identities[i].key->n) && 107 BN_cmp(pub_e, identities[i].key->e) == 0 && 108 BN_cmp(pub_n, identities[i].key->n) == 0) { 109 /* Decrypt the challenge using the private key. */ 110 rsa_private_decrypt(challenge, challenge, identities[i].key); 111 112 /* Compute the desired response. */ 113 switch (response_type) { 114 case 0:/* As of protocol 1.0 */ 115 /* This response type is no longer supported. */ 116 log("Compatibility with ssh protocol 1.0 no longer supported."); 117 buffer_put_char(&msg, SSH_AGENT_FAILURE); 118 goto send; 119 120 case 1:/* As of protocol 1.1 */ 121 /* The response is MD5 of decrypted challenge plus session id. */ 122 len = BN_num_bytes(challenge); 123 124 if (len <= 0 || len > 32) { 125 fatal("process_authentication_challenge: " 126 "bad challenge length %d", len); 127 } 128 memset(buf, 0, 32); 129 BN_bn2bin(challenge, buf + 32 - len); 130 MD5_Init(&md); 131 MD5_Update(&md, buf, 32); 132 MD5_Update(&md, session_id, 16); 133 MD5_Final(mdbuf, &md); 134 break; 135 136 default: 137 fatal("process_authentication_challenge: bad response_type %d", 138 response_type); 139 break; 140 } 141 142 /* Send the response. */ 143 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 144 for (i = 0; i < 16; i++) 145 buffer_put_char(&msg, mdbuf[i]); 146 147 goto send; 148 } 149 /* Unknown identity. Send failure. */ 150 buffer_put_char(&msg, SSH_AGENT_FAILURE); 151send: 152 buffer_put_int(&e->output, buffer_len(&msg)); 153 buffer_append(&e->output, buffer_ptr(&msg), 154 buffer_len(&msg)); 155 buffer_free(&msg); 156 BN_clear_free(pub_e); 157 BN_clear_free(pub_n); 158 BN_clear_free(challenge); 159} 160 161void 162process_remove_identity(SocketEntry *e) 163{ 164 unsigned int bits; 165 unsigned int i; 166 BIGNUM *dummy, *n; 167 168 dummy = BN_new(); 169 n = BN_new(); 170 171 /* Get the key from the packet. */ 172 bits = buffer_get_int(&e->input); 173 buffer_get_bignum(&e->input, dummy); 174 buffer_get_bignum(&e->input, n); 175 176 if (bits != BN_num_bits(n)) 177 error("Warning: identity keysize mismatch: actual %d, announced %d", 178 BN_num_bits(n), bits); 179 180 /* Check if we have the key. */ 181 for (i = 0; i < num_identities; i++) 182 if (BN_cmp(identities[i].key->n, n) == 0) { 183 /* 184 * We have this key. Free the old key. Since we 185 * don\'t want to leave empty slots in the middle of 186 * the array, we actually free the key there and copy 187 * data from the last entry. 188 */ 189 RSA_free(identities[i].key); 190 xfree(identities[i].comment); 191 if (i < num_identities - 1) 192 identities[i] = identities[num_identities - 1]; 193 num_identities--; 194 BN_clear_free(dummy); 195 BN_clear_free(n); 196 197 /* Send success. */ 198 buffer_put_int(&e->output, 1); 199 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 200 return; 201 } 202 /* We did not have the key. */ 203 BN_clear(dummy); 204 BN_clear(n); 205 206 /* Send failure. */ 207 buffer_put_int(&e->output, 1); 208 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 209} 210 211/* 212 * Removes all identities from the agent. 213 */ 214void 215process_remove_all_identities(SocketEntry *e) 216{ 217 unsigned int i; 218 219 /* Loop over all identities and clear the keys. */ 220 for (i = 0; i < num_identities; i++) { 221 RSA_free(identities[i].key); 222 xfree(identities[i].comment); 223 } 224 225 /* Mark that there are no identities. */ 226 num_identities = 0; 227 228 /* Send success. */ 229 buffer_put_int(&e->output, 1); 230 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 231 return; 232} 233 234/* 235 * Adds an identity to the agent. 236 */ 237void 238process_add_identity(SocketEntry *e) 239{ 240 RSA *k; 241 int i; 242 BIGNUM *aux; 243 BN_CTX *ctx; 244 245 if (num_identities == 0) 246 identities = xmalloc(sizeof(Identity)); 247 else 248 identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity)); 249 250 identities[num_identities].key = RSA_new(); 251 k = identities[num_identities].key; 252 buffer_get_int(&e->input); /* bits */ 253 k->n = BN_new(); 254 buffer_get_bignum(&e->input, k->n); 255 k->e = BN_new(); 256 buffer_get_bignum(&e->input, k->e); 257 k->d = BN_new(); 258 buffer_get_bignum(&e->input, k->d); 259 k->iqmp = BN_new(); 260 buffer_get_bignum(&e->input, k->iqmp); 261 /* SSH and SSL have p and q swapped */ 262 k->q = BN_new(); 263 buffer_get_bignum(&e->input, k->q); /* p */ 264 k->p = BN_new(); 265 buffer_get_bignum(&e->input, k->p); /* q */ 266 267 /* Generate additional parameters */ 268 aux = BN_new(); 269 ctx = BN_CTX_new(); 270 271 BN_sub(aux, k->q, BN_value_one()); 272 k->dmq1 = BN_new(); 273 BN_mod(k->dmq1, k->d, aux, ctx); 274 275 BN_sub(aux, k->p, BN_value_one()); 276 k->dmp1 = BN_new(); 277 BN_mod(k->dmp1, k->d, aux, ctx); 278 279 BN_clear_free(aux); 280 BN_CTX_free(ctx); 281 282 identities[num_identities].comment = buffer_get_string(&e->input, NULL); 283 284 /* Check if we already have the key. */ 285 for (i = 0; i < num_identities; i++) 286 if (BN_cmp(identities[i].key->n, k->n) == 0) { 287 /* 288 * We already have this key. Clear and free the new 289 * data and return success. 290 */ 291 RSA_free(k); 292 xfree(identities[num_identities].comment); 293 294 /* Send success. */ 295 buffer_put_int(&e->output, 1); 296 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 297 return; 298 } 299 /* Increment the number of identities. */ 300 num_identities++; 301 302 /* Send a success message. */ 303 buffer_put_int(&e->output, 1); 304 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 305} 306 307void 308process_message(SocketEntry *e) 309{ 310 unsigned int msg_len; 311 unsigned int type; 312 unsigned char *cp; 313 if (buffer_len(&e->input) < 5) 314 return; /* Incomplete message. */ 315 cp = (unsigned char *) buffer_ptr(&e->input); 316 msg_len = GET_32BIT(cp); 317 if (msg_len > 256 * 1024) { 318 shutdown(e->fd, SHUT_RDWR); 319 close(e->fd); 320 e->type = AUTH_UNUSED; 321 return; 322 } 323 if (buffer_len(&e->input) < msg_len + 4) 324 return; 325 buffer_consume(&e->input, 4); 326 type = buffer_get_char(&e->input); 327 328 switch (type) { 329 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 330 process_request_identity(e); 331 break; 332 case SSH_AGENTC_RSA_CHALLENGE: 333 process_authentication_challenge(e); 334 break; 335 case SSH_AGENTC_ADD_RSA_IDENTITY: 336 process_add_identity(e); 337 break; 338 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 339 process_remove_identity(e); 340 break; 341 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 342 process_remove_all_identities(e); 343 break; 344 default: 345 /* Unknown message. Respond with failure. */ 346 error("Unknown message %d", type); 347 buffer_clear(&e->input); 348 buffer_put_int(&e->output, 1); 349 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 350 break; 351 } 352} 353 354void 355new_socket(int type, int fd) 356{ 357 unsigned int i, old_alloc; 358 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) 359 error("fcntl O_NONBLOCK: %s", strerror(errno)); 360 361 if (fd > max_fd) 362 max_fd = fd; 363 364 for (i = 0; i < sockets_alloc; i++) 365 if (sockets[i].type == AUTH_UNUSED) { 366 sockets[i].fd = fd; 367 sockets[i].type = type; 368 buffer_init(&sockets[i].input); 369 buffer_init(&sockets[i].output); 370 return; 371 } 372 old_alloc = sockets_alloc; 373 sockets_alloc += 10; 374 if (sockets) 375 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); 376 else 377 sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); 378 for (i = old_alloc; i < sockets_alloc; i++) 379 sockets[i].type = AUTH_UNUSED; 380 sockets[old_alloc].type = type; 381 sockets[old_alloc].fd = fd; 382 buffer_init(&sockets[old_alloc].input); 383 buffer_init(&sockets[old_alloc].output); 384} 385 386void 387prepare_select(fd_set *readset, fd_set *writeset) 388{ 389 unsigned int i; 390 for (i = 0; i < sockets_alloc; i++) 391 switch (sockets[i].type) { 392 case AUTH_SOCKET: 393 case AUTH_CONNECTION: 394 FD_SET(sockets[i].fd, readset); 395 if (buffer_len(&sockets[i].output) > 0) 396 FD_SET(sockets[i].fd, writeset); 397 break; 398 case AUTH_UNUSED: 399 break; 400 default: 401 fatal("Unknown socket type %d", sockets[i].type); 402 break; 403 } 404} 405 406void 407after_select(fd_set *readset, fd_set *writeset) 408{ 409 unsigned int i; 410 int len, sock; 411 char buf[1024]; 412 struct sockaddr_un sunaddr; 413 414 for (i = 0; i < sockets_alloc; i++) 415 switch (sockets[i].type) { 416 case AUTH_UNUSED: 417 break; 418 case AUTH_SOCKET: 419 if (FD_ISSET(sockets[i].fd, readset)) { 420 len = sizeof(sunaddr); 421 sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &len); 422 if (sock < 0) { 423 perror("accept from AUTH_SOCKET"); 424 break; 425 } 426 new_socket(AUTH_CONNECTION, sock); 427 } 428 break; 429 case AUTH_CONNECTION: 430 if (buffer_len(&sockets[i].output) > 0 && 431 FD_ISSET(sockets[i].fd, writeset)) { 432 len = write(sockets[i].fd, buffer_ptr(&sockets[i].output), 433 buffer_len(&sockets[i].output)); 434 if (len <= 0) { 435 shutdown(sockets[i].fd, SHUT_RDWR); 436 close(sockets[i].fd); 437 sockets[i].type = AUTH_UNUSED; 438 break; 439 } 440 buffer_consume(&sockets[i].output, len); 441 } 442 if (FD_ISSET(sockets[i].fd, readset)) { 443 len = read(sockets[i].fd, buf, sizeof(buf)); 444 if (len <= 0) { 445 shutdown(sockets[i].fd, SHUT_RDWR); 446 close(sockets[i].fd); 447 sockets[i].type = AUTH_UNUSED; 448 break; 449 } 450 buffer_append(&sockets[i].input, buf, len); 451 process_message(&sockets[i]); 452 } 453 break; 454 default: 455 fatal("Unknown type %d", sockets[i].type); 456 } 457} 458 459void 460check_parent_exists(int sig) 461{ 462 if (kill(parent_pid, 0) < 0) { 463 /* printf("Parent has died - Authentication agent exiting.\n"); */ 464 exit(1); 465 } 466 signal(SIGALRM, check_parent_exists); 467 alarm(10); 468} 469 470void 471cleanup_socket(void) 472{ 473 remove(socket_name); 474 rmdir(socket_dir); 475} 476 477void 478cleanup_exit(int i) 479{ 480 cleanup_socket(); 481 exit(i); 482} 483 484void 485usage() 486{ 487 fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION); 488 fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n", 489 __progname); 490 exit(1); 491} 492 493int 494main(int ac, char **av) 495{ 496 fd_set readset, writeset; 497 int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch; 498 struct sockaddr_un sunaddr; 499 pid_t pid; 500 char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; 501 502 /* check if RSA support exists */ 503 if (rsa_alive() == 0) { 504 fprintf(stderr, 505 "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", 506 __progname); 507 exit(1); 508 } 509 while ((ch = getopt(ac, av, "cks")) != -1) { 510 switch (ch) { 511 case 'c': 512 if (s_flag) 513 usage(); 514 c_flag++; 515 break; 516 case 'k': 517 k_flag++; 518 break; 519 case 's': 520 if (c_flag) 521 usage(); 522 s_flag++; 523 break; 524 default: 525 usage(); 526 } 527 } 528 ac -= optind; 529 av += optind; 530 531 if (ac > 0 && (c_flag || k_flag || s_flag)) 532 usage(); 533 534 if (ac == 0 && !c_flag && !k_flag && !s_flag) { 535 shell = getenv("SHELL"); 536 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 537 c_flag = 1; 538 } 539 if (k_flag) { 540 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 541 if (pidstr == NULL) { 542 fprintf(stderr, "%s not set, cannot kill agent\n", 543 SSH_AGENTPID_ENV_NAME); 544 exit(1); 545 } 546 pid = atoi(pidstr); 547 if (pid < 1) { /* XXX PID_MAX check too */ 548 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 549 SSH_AGENTPID_ENV_NAME, pidstr); 550 exit(1); 551 } 552 if (kill(pid, SIGTERM) == -1) { 553 perror("kill"); 554 exit(1); 555 } 556 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 557 printf(format, SSH_AUTHSOCKET_ENV_NAME); 558 printf(format, SSH_AGENTPID_ENV_NAME); 559 printf("echo Agent pid %d killed;\n", pid); 560 exit(0); 561 } 562 parent_pid = getpid(); 563 564 /* Create private directory for agent socket */ 565 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); 566 if (mkdtemp(socket_dir) == NULL) { 567 perror("mkdtemp: private socket dir"); 568 exit(1); 569 } 570 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, 571 parent_pid); 572 573 /* 574 * Create socket early so it will exist before command gets run from 575 * the parent. 576 */ 577 sock = socket(AF_UNIX, SOCK_STREAM, 0); 578 if (sock < 0) { 579 perror("socket"); 580 cleanup_exit(1); 581 } 582 memset(&sunaddr, 0, sizeof(sunaddr)); 583 sunaddr.sun_family = AF_UNIX; 584 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 585 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { 586 perror("bind"); 587 cleanup_exit(1); 588 } 589 if (listen(sock, 5) < 0) { 590 perror("listen"); 591 cleanup_exit(1); 592 } 593 /* 594 * Fork, and have the parent execute the command, if any, or present 595 * the socket data. The child continues as the authentication agent. 596 */ 597 pid = fork(); 598 if (pid == -1) { 599 perror("fork"); 600 exit(1); 601 } 602 if (pid != 0) { /* Parent - execute the given command. */ 603 close(sock); 604 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid); 605 if (ac == 0) { 606 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 607 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 608 SSH_AUTHSOCKET_ENV_NAME); 609 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 610 SSH_AGENTPID_ENV_NAME); 611 printf("echo Agent pid %d;\n", pid); 612 exit(0); 613 } 614 setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1); 615 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1); 616 execvp(av[0], av); 617 perror(av[0]); 618 exit(1); 619 } 620 close(0); 621 close(1); 622 close(2); 623 624 if (setsid() == -1) { 625 perror("setsid"); 626 cleanup_exit(1); 627 } 628 if (atexit(cleanup_socket) < 0) { 629 perror("atexit"); 630 cleanup_exit(1); 631 } 632 new_socket(AUTH_SOCKET, sock); 633 if (ac > 0) { 634 signal(SIGALRM, check_parent_exists); 635 alarm(10); 636 } 637 signal(SIGINT, SIG_IGN); 638 signal(SIGPIPE, SIG_IGN); 639 signal(SIGHUP, cleanup_exit); 640 signal(SIGTERM, cleanup_exit); 641 while (1) { 642 FD_ZERO(&readset); 643 FD_ZERO(&writeset); 644 prepare_select(&readset, &writeset); 645 if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) { 646 if (errno == EINTR) 647 continue; 648 exit(1); 649 } 650 after_select(&readset, &writeset); 651 } 652 /* NOTREACHED */ 653}
| 27 28typedef struct { 29 int fd; 30 enum { 31 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION 32 } type; 33 Buffer input; 34 Buffer output; 35} SocketEntry; 36 37unsigned int sockets_alloc = 0; 38SocketEntry *sockets = NULL; 39 40typedef struct { 41 RSA *key; 42 char *comment; 43} Identity; 44 45unsigned int num_identities = 0; 46Identity *identities = NULL; 47 48int max_fd = 0; 49 50/* pid of shell == parent of agent */ 51int parent_pid = -1; 52 53/* pathname and directory for AUTH_SOCKET */ 54char socket_name[1024]; 55char socket_dir[1024]; 56 57extern char *__progname; 58 59void 60process_request_identity(SocketEntry *e) 61{ 62 Buffer msg; 63 int i; 64 65 buffer_init(&msg); 66 buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER); 67 buffer_put_int(&msg, num_identities); 68 for (i = 0; i < num_identities; i++) { 69 buffer_put_int(&msg, BN_num_bits(identities[i].key->n)); 70 buffer_put_bignum(&msg, identities[i].key->e); 71 buffer_put_bignum(&msg, identities[i].key->n); 72 buffer_put_string(&msg, identities[i].comment, 73 strlen(identities[i].comment)); 74 } 75 buffer_put_int(&e->output, buffer_len(&msg)); 76 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); 77 buffer_free(&msg); 78} 79 80void 81process_authentication_challenge(SocketEntry *e) 82{ 83 int i, pub_bits, len; 84 BIGNUM *pub_e, *pub_n, *challenge; 85 Buffer msg; 86 MD5_CTX md; 87 unsigned char buf[32], mdbuf[16], session_id[16]; 88 unsigned int response_type; 89 90 buffer_init(&msg); 91 pub_e = BN_new(); 92 pub_n = BN_new(); 93 challenge = BN_new(); 94 pub_bits = buffer_get_int(&e->input); 95 buffer_get_bignum(&e->input, pub_e); 96 buffer_get_bignum(&e->input, pub_n); 97 buffer_get_bignum(&e->input, challenge); 98 if (buffer_len(&e->input) == 0) { 99 /* Compatibility code for old servers. */ 100 memset(session_id, 0, 16); 101 response_type = 0; 102 } else { 103 /* New code. */ 104 buffer_get(&e->input, (char *) session_id, 16); 105 response_type = buffer_get_int(&e->input); 106 } 107 for (i = 0; i < num_identities; i++) 108 if (pub_bits == BN_num_bits(identities[i].key->n) && 109 BN_cmp(pub_e, identities[i].key->e) == 0 && 110 BN_cmp(pub_n, identities[i].key->n) == 0) { 111 /* Decrypt the challenge using the private key. */ 112 rsa_private_decrypt(challenge, challenge, identities[i].key); 113 114 /* Compute the desired response. */ 115 switch (response_type) { 116 case 0:/* As of protocol 1.0 */ 117 /* This response type is no longer supported. */ 118 log("Compatibility with ssh protocol 1.0 no longer supported."); 119 buffer_put_char(&msg, SSH_AGENT_FAILURE); 120 goto send; 121 122 case 1:/* As of protocol 1.1 */ 123 /* The response is MD5 of decrypted challenge plus session id. */ 124 len = BN_num_bytes(challenge); 125 126 if (len <= 0 || len > 32) { 127 fatal("process_authentication_challenge: " 128 "bad challenge length %d", len); 129 } 130 memset(buf, 0, 32); 131 BN_bn2bin(challenge, buf + 32 - len); 132 MD5_Init(&md); 133 MD5_Update(&md, buf, 32); 134 MD5_Update(&md, session_id, 16); 135 MD5_Final(mdbuf, &md); 136 break; 137 138 default: 139 fatal("process_authentication_challenge: bad response_type %d", 140 response_type); 141 break; 142 } 143 144 /* Send the response. */ 145 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); 146 for (i = 0; i < 16; i++) 147 buffer_put_char(&msg, mdbuf[i]); 148 149 goto send; 150 } 151 /* Unknown identity. Send failure. */ 152 buffer_put_char(&msg, SSH_AGENT_FAILURE); 153send: 154 buffer_put_int(&e->output, buffer_len(&msg)); 155 buffer_append(&e->output, buffer_ptr(&msg), 156 buffer_len(&msg)); 157 buffer_free(&msg); 158 BN_clear_free(pub_e); 159 BN_clear_free(pub_n); 160 BN_clear_free(challenge); 161} 162 163void 164process_remove_identity(SocketEntry *e) 165{ 166 unsigned int bits; 167 unsigned int i; 168 BIGNUM *dummy, *n; 169 170 dummy = BN_new(); 171 n = BN_new(); 172 173 /* Get the key from the packet. */ 174 bits = buffer_get_int(&e->input); 175 buffer_get_bignum(&e->input, dummy); 176 buffer_get_bignum(&e->input, n); 177 178 if (bits != BN_num_bits(n)) 179 error("Warning: identity keysize mismatch: actual %d, announced %d", 180 BN_num_bits(n), bits); 181 182 /* Check if we have the key. */ 183 for (i = 0; i < num_identities; i++) 184 if (BN_cmp(identities[i].key->n, n) == 0) { 185 /* 186 * We have this key. Free the old key. Since we 187 * don\'t want to leave empty slots in the middle of 188 * the array, we actually free the key there and copy 189 * data from the last entry. 190 */ 191 RSA_free(identities[i].key); 192 xfree(identities[i].comment); 193 if (i < num_identities - 1) 194 identities[i] = identities[num_identities - 1]; 195 num_identities--; 196 BN_clear_free(dummy); 197 BN_clear_free(n); 198 199 /* Send success. */ 200 buffer_put_int(&e->output, 1); 201 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 202 return; 203 } 204 /* We did not have the key. */ 205 BN_clear(dummy); 206 BN_clear(n); 207 208 /* Send failure. */ 209 buffer_put_int(&e->output, 1); 210 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 211} 212 213/* 214 * Removes all identities from the agent. 215 */ 216void 217process_remove_all_identities(SocketEntry *e) 218{ 219 unsigned int i; 220 221 /* Loop over all identities and clear the keys. */ 222 for (i = 0; i < num_identities; i++) { 223 RSA_free(identities[i].key); 224 xfree(identities[i].comment); 225 } 226 227 /* Mark that there are no identities. */ 228 num_identities = 0; 229 230 /* Send success. */ 231 buffer_put_int(&e->output, 1); 232 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 233 return; 234} 235 236/* 237 * Adds an identity to the agent. 238 */ 239void 240process_add_identity(SocketEntry *e) 241{ 242 RSA *k; 243 int i; 244 BIGNUM *aux; 245 BN_CTX *ctx; 246 247 if (num_identities == 0) 248 identities = xmalloc(sizeof(Identity)); 249 else 250 identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity)); 251 252 identities[num_identities].key = RSA_new(); 253 k = identities[num_identities].key; 254 buffer_get_int(&e->input); /* bits */ 255 k->n = BN_new(); 256 buffer_get_bignum(&e->input, k->n); 257 k->e = BN_new(); 258 buffer_get_bignum(&e->input, k->e); 259 k->d = BN_new(); 260 buffer_get_bignum(&e->input, k->d); 261 k->iqmp = BN_new(); 262 buffer_get_bignum(&e->input, k->iqmp); 263 /* SSH and SSL have p and q swapped */ 264 k->q = BN_new(); 265 buffer_get_bignum(&e->input, k->q); /* p */ 266 k->p = BN_new(); 267 buffer_get_bignum(&e->input, k->p); /* q */ 268 269 /* Generate additional parameters */ 270 aux = BN_new(); 271 ctx = BN_CTX_new(); 272 273 BN_sub(aux, k->q, BN_value_one()); 274 k->dmq1 = BN_new(); 275 BN_mod(k->dmq1, k->d, aux, ctx); 276 277 BN_sub(aux, k->p, BN_value_one()); 278 k->dmp1 = BN_new(); 279 BN_mod(k->dmp1, k->d, aux, ctx); 280 281 BN_clear_free(aux); 282 BN_CTX_free(ctx); 283 284 identities[num_identities].comment = buffer_get_string(&e->input, NULL); 285 286 /* Check if we already have the key. */ 287 for (i = 0; i < num_identities; i++) 288 if (BN_cmp(identities[i].key->n, k->n) == 0) { 289 /* 290 * We already have this key. Clear and free the new 291 * data and return success. 292 */ 293 RSA_free(k); 294 xfree(identities[num_identities].comment); 295 296 /* Send success. */ 297 buffer_put_int(&e->output, 1); 298 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 299 return; 300 } 301 /* Increment the number of identities. */ 302 num_identities++; 303 304 /* Send a success message. */ 305 buffer_put_int(&e->output, 1); 306 buffer_put_char(&e->output, SSH_AGENT_SUCCESS); 307} 308 309void 310process_message(SocketEntry *e) 311{ 312 unsigned int msg_len; 313 unsigned int type; 314 unsigned char *cp; 315 if (buffer_len(&e->input) < 5) 316 return; /* Incomplete message. */ 317 cp = (unsigned char *) buffer_ptr(&e->input); 318 msg_len = GET_32BIT(cp); 319 if (msg_len > 256 * 1024) { 320 shutdown(e->fd, SHUT_RDWR); 321 close(e->fd); 322 e->type = AUTH_UNUSED; 323 return; 324 } 325 if (buffer_len(&e->input) < msg_len + 4) 326 return; 327 buffer_consume(&e->input, 4); 328 type = buffer_get_char(&e->input); 329 330 switch (type) { 331 case SSH_AGENTC_REQUEST_RSA_IDENTITIES: 332 process_request_identity(e); 333 break; 334 case SSH_AGENTC_RSA_CHALLENGE: 335 process_authentication_challenge(e); 336 break; 337 case SSH_AGENTC_ADD_RSA_IDENTITY: 338 process_add_identity(e); 339 break; 340 case SSH_AGENTC_REMOVE_RSA_IDENTITY: 341 process_remove_identity(e); 342 break; 343 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 344 process_remove_all_identities(e); 345 break; 346 default: 347 /* Unknown message. Respond with failure. */ 348 error("Unknown message %d", type); 349 buffer_clear(&e->input); 350 buffer_put_int(&e->output, 1); 351 buffer_put_char(&e->output, SSH_AGENT_FAILURE); 352 break; 353 } 354} 355 356void 357new_socket(int type, int fd) 358{ 359 unsigned int i, old_alloc; 360 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) 361 error("fcntl O_NONBLOCK: %s", strerror(errno)); 362 363 if (fd > max_fd) 364 max_fd = fd; 365 366 for (i = 0; i < sockets_alloc; i++) 367 if (sockets[i].type == AUTH_UNUSED) { 368 sockets[i].fd = fd; 369 sockets[i].type = type; 370 buffer_init(&sockets[i].input); 371 buffer_init(&sockets[i].output); 372 return; 373 } 374 old_alloc = sockets_alloc; 375 sockets_alloc += 10; 376 if (sockets) 377 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); 378 else 379 sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); 380 for (i = old_alloc; i < sockets_alloc; i++) 381 sockets[i].type = AUTH_UNUSED; 382 sockets[old_alloc].type = type; 383 sockets[old_alloc].fd = fd; 384 buffer_init(&sockets[old_alloc].input); 385 buffer_init(&sockets[old_alloc].output); 386} 387 388void 389prepare_select(fd_set *readset, fd_set *writeset) 390{ 391 unsigned int i; 392 for (i = 0; i < sockets_alloc; i++) 393 switch (sockets[i].type) { 394 case AUTH_SOCKET: 395 case AUTH_CONNECTION: 396 FD_SET(sockets[i].fd, readset); 397 if (buffer_len(&sockets[i].output) > 0) 398 FD_SET(sockets[i].fd, writeset); 399 break; 400 case AUTH_UNUSED: 401 break; 402 default: 403 fatal("Unknown socket type %d", sockets[i].type); 404 break; 405 } 406} 407 408void 409after_select(fd_set *readset, fd_set *writeset) 410{ 411 unsigned int i; 412 int len, sock; 413 char buf[1024]; 414 struct sockaddr_un sunaddr; 415 416 for (i = 0; i < sockets_alloc; i++) 417 switch (sockets[i].type) { 418 case AUTH_UNUSED: 419 break; 420 case AUTH_SOCKET: 421 if (FD_ISSET(sockets[i].fd, readset)) { 422 len = sizeof(sunaddr); 423 sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &len); 424 if (sock < 0) { 425 perror("accept from AUTH_SOCKET"); 426 break; 427 } 428 new_socket(AUTH_CONNECTION, sock); 429 } 430 break; 431 case AUTH_CONNECTION: 432 if (buffer_len(&sockets[i].output) > 0 && 433 FD_ISSET(sockets[i].fd, writeset)) { 434 len = write(sockets[i].fd, buffer_ptr(&sockets[i].output), 435 buffer_len(&sockets[i].output)); 436 if (len <= 0) { 437 shutdown(sockets[i].fd, SHUT_RDWR); 438 close(sockets[i].fd); 439 sockets[i].type = AUTH_UNUSED; 440 break; 441 } 442 buffer_consume(&sockets[i].output, len); 443 } 444 if (FD_ISSET(sockets[i].fd, readset)) { 445 len = read(sockets[i].fd, buf, sizeof(buf)); 446 if (len <= 0) { 447 shutdown(sockets[i].fd, SHUT_RDWR); 448 close(sockets[i].fd); 449 sockets[i].type = AUTH_UNUSED; 450 break; 451 } 452 buffer_append(&sockets[i].input, buf, len); 453 process_message(&sockets[i]); 454 } 455 break; 456 default: 457 fatal("Unknown type %d", sockets[i].type); 458 } 459} 460 461void 462check_parent_exists(int sig) 463{ 464 if (kill(parent_pid, 0) < 0) { 465 /* printf("Parent has died - Authentication agent exiting.\n"); */ 466 exit(1); 467 } 468 signal(SIGALRM, check_parent_exists); 469 alarm(10); 470} 471 472void 473cleanup_socket(void) 474{ 475 remove(socket_name); 476 rmdir(socket_dir); 477} 478 479void 480cleanup_exit(int i) 481{ 482 cleanup_socket(); 483 exit(i); 484} 485 486void 487usage() 488{ 489 fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION); 490 fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n", 491 __progname); 492 exit(1); 493} 494 495int 496main(int ac, char **av) 497{ 498 fd_set readset, writeset; 499 int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch; 500 struct sockaddr_un sunaddr; 501 pid_t pid; 502 char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; 503 504 /* check if RSA support exists */ 505 if (rsa_alive() == 0) { 506 fprintf(stderr, 507 "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", 508 __progname); 509 exit(1); 510 } 511 while ((ch = getopt(ac, av, "cks")) != -1) { 512 switch (ch) { 513 case 'c': 514 if (s_flag) 515 usage(); 516 c_flag++; 517 break; 518 case 'k': 519 k_flag++; 520 break; 521 case 's': 522 if (c_flag) 523 usage(); 524 s_flag++; 525 break; 526 default: 527 usage(); 528 } 529 } 530 ac -= optind; 531 av += optind; 532 533 if (ac > 0 && (c_flag || k_flag || s_flag)) 534 usage(); 535 536 if (ac == 0 && !c_flag && !k_flag && !s_flag) { 537 shell = getenv("SHELL"); 538 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) 539 c_flag = 1; 540 } 541 if (k_flag) { 542 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 543 if (pidstr == NULL) { 544 fprintf(stderr, "%s not set, cannot kill agent\n", 545 SSH_AGENTPID_ENV_NAME); 546 exit(1); 547 } 548 pid = atoi(pidstr); 549 if (pid < 1) { /* XXX PID_MAX check too */ 550 fprintf(stderr, "%s=\"%s\", which is not a good PID\n", 551 SSH_AGENTPID_ENV_NAME, pidstr); 552 exit(1); 553 } 554 if (kill(pid, SIGTERM) == -1) { 555 perror("kill"); 556 exit(1); 557 } 558 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 559 printf(format, SSH_AUTHSOCKET_ENV_NAME); 560 printf(format, SSH_AGENTPID_ENV_NAME); 561 printf("echo Agent pid %d killed;\n", pid); 562 exit(0); 563 } 564 parent_pid = getpid(); 565 566 /* Create private directory for agent socket */ 567 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); 568 if (mkdtemp(socket_dir) == NULL) { 569 perror("mkdtemp: private socket dir"); 570 exit(1); 571 } 572 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, 573 parent_pid); 574 575 /* 576 * Create socket early so it will exist before command gets run from 577 * the parent. 578 */ 579 sock = socket(AF_UNIX, SOCK_STREAM, 0); 580 if (sock < 0) { 581 perror("socket"); 582 cleanup_exit(1); 583 } 584 memset(&sunaddr, 0, sizeof(sunaddr)); 585 sunaddr.sun_family = AF_UNIX; 586 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); 587 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { 588 perror("bind"); 589 cleanup_exit(1); 590 } 591 if (listen(sock, 5) < 0) { 592 perror("listen"); 593 cleanup_exit(1); 594 } 595 /* 596 * Fork, and have the parent execute the command, if any, or present 597 * the socket data. The child continues as the authentication agent. 598 */ 599 pid = fork(); 600 if (pid == -1) { 601 perror("fork"); 602 exit(1); 603 } 604 if (pid != 0) { /* Parent - execute the given command. */ 605 close(sock); 606 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid); 607 if (ac == 0) { 608 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 609 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 610 SSH_AUTHSOCKET_ENV_NAME); 611 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 612 SSH_AGENTPID_ENV_NAME); 613 printf("echo Agent pid %d;\n", pid); 614 exit(0); 615 } 616 setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1); 617 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1); 618 execvp(av[0], av); 619 perror(av[0]); 620 exit(1); 621 } 622 close(0); 623 close(1); 624 close(2); 625 626 if (setsid() == -1) { 627 perror("setsid"); 628 cleanup_exit(1); 629 } 630 if (atexit(cleanup_socket) < 0) { 631 perror("atexit"); 632 cleanup_exit(1); 633 } 634 new_socket(AUTH_SOCKET, sock); 635 if (ac > 0) { 636 signal(SIGALRM, check_parent_exists); 637 alarm(10); 638 } 639 signal(SIGINT, SIG_IGN); 640 signal(SIGPIPE, SIG_IGN); 641 signal(SIGHUP, cleanup_exit); 642 signal(SIGTERM, cleanup_exit); 643 while (1) { 644 FD_ZERO(&readset); 645 FD_ZERO(&writeset); 646 prepare_select(&readset, &writeset); 647 if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) { 648 if (errno == EINTR) 649 continue; 650 exit(1); 651 } 652 after_select(&readset, &writeset); 653 } 654 /* NOTREACHED */ 655}
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