1/* $OpenBSD: authfd.c,v 1.86 2011/07/06 18:09:21 tedu Exp $ */ 2/* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * Functions for connecting the local authentication agent. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * SSH2 implementation, 15 * Copyright (c) 2000 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 40#include <sys/types.h> 41#include <sys/un.h> 42#include <sys/socket.h> 43 44#include <openssl/evp.h> 45 46#include <openssl/crypto.h> 47#include <fcntl.h> 48#include <stdlib.h> 49#include <signal.h> 50#include <stdarg.h> 51#include <string.h> 52#include <unistd.h> 53 54#include "xmalloc.h" 55#include "ssh.h" 56#include "rsa.h" 57#include "buffer.h" 58#include "key.h" 59#include "authfd.h" 60#include "cipher.h" 61#include "kex.h" 62#include "compat.h" 63#include "log.h" 64#include "atomicio.h" 65#include "misc.h" 66 67static int agent_present = 0; 68 69/* helper */ 70int decode_reply(int type); 71 72/* macro to check for "agent failure" message */ 73#define agent_failed(x) \ 74 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \ 75 (x == SSH2_AGENT_FAILURE)) 76 77int 78ssh_agent_present(void) 79{ 80 int authfd; 81 82 if (agent_present) 83 return 1; 84 if ((authfd = ssh_get_authentication_socket()) == -1) 85 return 0; 86 else { 87 ssh_close_authentication_socket(authfd); 88 return 1; 89 } 90} 91 92/* Returns the number of the authentication fd, or -1 if there is none. */ 93 94int 95ssh_get_authentication_socket(void) 96{ 97 const char *authsocket; 98 int sock; 99 struct sockaddr_un sunaddr; 100 101 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); 102 if (!authsocket) 103 return -1; 104 105 bzero(&sunaddr, sizeof(sunaddr)); 106 sunaddr.sun_family = AF_UNIX; 107 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); 108 109 sock = socket(AF_UNIX, SOCK_STREAM, 0); 110 if (sock < 0) 111 return -1; 112 113 /* close on exec */ 114 if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1) { 115 close(sock); 116 return -1; 117 } 118 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) { 119 close(sock); 120 return -1; 121 } 122 agent_present = 1; 123 return sock; 124} 125 126static int 127ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply) 128{ 129 u_int l, len; 130 char buf[1024]; 131 132 /* Get the length of the message, and format it in the buffer. */ 133 len = buffer_len(request); 134 put_u32(buf, len); 135 136 /* Send the length and then the packet to the agent. */ 137 if (atomicio(vwrite, auth->fd, buf, 4) != 4 || 138 atomicio(vwrite, auth->fd, buffer_ptr(request), 139 buffer_len(request)) != buffer_len(request)) { 140 error("Error writing to authentication socket."); 141 return 0; 142 } 143 /* 144 * Wait for response from the agent. First read the length of the 145 * response packet. 146 */ 147 if (atomicio(read, auth->fd, buf, 4) != 4) { 148 error("Error reading response length from authentication socket."); 149 return 0; 150 } 151 152 /* Extract the length, and check it for sanity. */ 153 len = get_u32(buf); 154 if (len > 256 * 1024) 155 fatal("Authentication response too long: %u", len); 156 157 /* Read the rest of the response in to the buffer. */ 158 buffer_clear(reply); 159 while (len > 0) { 160 l = len; 161 if (l > sizeof(buf)) 162 l = sizeof(buf); 163 if (atomicio(read, auth->fd, buf, l) != l) { 164 error("Error reading response from authentication socket."); 165 return 0; 166 } 167 buffer_append(reply, buf, l); 168 len -= l; 169 } 170 return 1; 171} 172 173/* 174 * Closes the agent socket if it should be closed (depends on how it was 175 * obtained). The argument must have been returned by 176 * ssh_get_authentication_socket(). 177 */ 178 179void 180ssh_close_authentication_socket(int sock) 181{ 182 if (getenv(SSH_AUTHSOCKET_ENV_NAME)) 183 close(sock); 184} 185 186/* 187 * Opens and connects a private socket for communication with the 188 * authentication agent. Returns the file descriptor (which must be 189 * shut down and closed by the caller when no longer needed). 190 * Returns NULL if an error occurred and the connection could not be 191 * opened. 192 */ 193 194AuthenticationConnection * 195ssh_get_authentication_connection(void) 196{ 197 AuthenticationConnection *auth; 198 int sock; 199 200 sock = ssh_get_authentication_socket(); 201 202 /* 203 * Fail if we couldn't obtain a connection. This happens if we 204 * exited due to a timeout. 205 */ 206 if (sock < 0) 207 return NULL; 208 209 auth = xmalloc(sizeof(*auth)); 210 auth->fd = sock; 211 buffer_init(&auth->identities); 212 auth->howmany = 0; 213 214 return auth; 215} 216 217/* 218 * Closes the connection to the authentication agent and frees any associated 219 * memory. 220 */ 221 222void 223ssh_close_authentication_connection(AuthenticationConnection *auth) 224{ 225 buffer_free(&auth->identities); 226 close(auth->fd); 227 xfree(auth); 228} 229 230/* Lock/unlock agent */ 231int 232ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password) 233{ 234 int type; 235 Buffer msg; 236 237 buffer_init(&msg); 238 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK); 239 buffer_put_cstring(&msg, password); 240 241 if (ssh_request_reply(auth, &msg, &msg) == 0) { 242 buffer_free(&msg); 243 return 0; 244 } 245 type = buffer_get_char(&msg); 246 buffer_free(&msg); 247 return decode_reply(type); 248} 249 250/* 251 * Returns the first authentication identity held by the agent. 252 */ 253 254int 255ssh_get_num_identities(AuthenticationConnection *auth, int version) 256{ 257 int type, code1 = 0, code2 = 0; 258 Buffer request; 259 260 switch (version) { 261 case 1: 262 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES; 263 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER; 264 break; 265 case 2: 266 code1 = SSH2_AGENTC_REQUEST_IDENTITIES; 267 code2 = SSH2_AGENT_IDENTITIES_ANSWER; 268 break; 269 default: 270 return 0; 271 } 272 273 /* 274 * Send a message to the agent requesting for a list of the 275 * identities it can represent. 276 */ 277 buffer_init(&request); 278 buffer_put_char(&request, code1); 279 280 buffer_clear(&auth->identities); 281 if (ssh_request_reply(auth, &request, &auth->identities) == 0) { 282 buffer_free(&request); 283 return 0; 284 } 285 buffer_free(&request); 286 287 /* Get message type, and verify that we got a proper answer. */ 288 type = buffer_get_char(&auth->identities); 289 if (agent_failed(type)) { 290 return 0; 291 } else if (type != code2) { 292 fatal("Bad authentication reply message type: %d", type); 293 } 294 295 /* Get the number of entries in the response and check it for sanity. */ 296 auth->howmany = buffer_get_int(&auth->identities); 297 if ((u_int)auth->howmany > 1024) 298 fatal("Too many identities in authentication reply: %d", 299 auth->howmany); 300 301 return auth->howmany; 302} 303 304Key * 305ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version) 306{ 307 /* get number of identities and return the first entry (if any). */ 308 if (ssh_get_num_identities(auth, version) > 0) 309 return ssh_get_next_identity(auth, comment, version); 310 return NULL; 311} 312 313Key * 314ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version) 315{ 316 int keybits; 317 u_int bits; 318 u_char *blob; 319 u_int blen; 320 Key *key = NULL; 321 322 /* Return failure if no more entries. */ 323 if (auth->howmany <= 0) 324 return NULL; 325 326 /* 327 * Get the next entry from the packet. These will abort with a fatal 328 * error if the packet is too short or contains corrupt data. 329 */ 330 switch (version) { 331 case 1: 332 key = key_new(KEY_RSA1); 333 bits = buffer_get_int(&auth->identities); 334 buffer_get_bignum(&auth->identities, key->rsa->e); 335 buffer_get_bignum(&auth->identities, key->rsa->n); 336 *comment = buffer_get_string(&auth->identities, NULL); 337 keybits = BN_num_bits(key->rsa->n); 338 if (keybits < 0 || bits != (u_int)keybits) 339 logit("Warning: identity keysize mismatch: actual %d, announced %u", 340 BN_num_bits(key->rsa->n), bits); 341 break; 342 case 2: 343 blob = buffer_get_string(&auth->identities, &blen); 344 *comment = buffer_get_string(&auth->identities, NULL); 345 key = key_from_blob(blob, blen); 346 xfree(blob); 347 break; 348 default: 349 return NULL; 350 } 351 /* Decrement the number of remaining entries. */ 352 auth->howmany--; 353 return key; 354} 355 356/* 357 * Generates a random challenge, sends it to the agent, and waits for 358 * response from the agent. Returns true (non-zero) if the agent gave the 359 * correct answer, zero otherwise. Response type selects the style of 360 * response desired, with 0 corresponding to protocol version 1.0 (no longer 361 * supported) and 1 corresponding to protocol version 1.1. 362 */ 363 364int 365ssh_decrypt_challenge(AuthenticationConnection *auth, 366 Key* key, BIGNUM *challenge, 367 u_char session_id[16], 368 u_int response_type, 369 u_char response[16]) 370{ 371 Buffer buffer; 372 int success = 0; 373 int i; 374 int type; 375 376 if (key->type != KEY_RSA1) 377 return 0; 378 if (response_type == 0) { 379 logit("Compatibility with ssh protocol version 1.0 no longer supported."); 380 return 0; 381 } 382 buffer_init(&buffer); 383 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE); 384 buffer_put_int(&buffer, BN_num_bits(key->rsa->n)); 385 buffer_put_bignum(&buffer, key->rsa->e); 386 buffer_put_bignum(&buffer, key->rsa->n); 387 buffer_put_bignum(&buffer, challenge); 388 buffer_append(&buffer, session_id, 16); 389 buffer_put_int(&buffer, response_type); 390 391 if (ssh_request_reply(auth, &buffer, &buffer) == 0) { 392 buffer_free(&buffer); 393 return 0; 394 } 395 type = buffer_get_char(&buffer); 396 397 if (agent_failed(type)) { 398 logit("Agent admitted failure to authenticate using the key."); 399 } else if (type != SSH_AGENT_RSA_RESPONSE) { 400 fatal("Bad authentication response: %d", type); 401 } else { 402 success = 1; 403 /* 404 * Get the response from the packet. This will abort with a 405 * fatal error if the packet is corrupt. 406 */ 407 for (i = 0; i < 16; i++) 408 response[i] = (u_char)buffer_get_char(&buffer); 409 } 410 buffer_free(&buffer); 411 return success; 412} 413 414/* ask agent to sign data, returns -1 on error, 0 on success */ 415int 416ssh_agent_sign(AuthenticationConnection *auth, 417 Key *key, 418 u_char **sigp, u_int *lenp, 419 u_char *data, u_int datalen) 420{ 421 extern int datafellows; 422 Buffer msg; 423 u_char *blob; 424 u_int blen; 425 int type, flags = 0; 426 int ret = -1; 427 428 if (key_to_blob(key, &blob, &blen) == 0) 429 return -1; 430 431 if (datafellows & SSH_BUG_SIGBLOB) 432 flags = SSH_AGENT_OLD_SIGNATURE; 433 434 buffer_init(&msg); 435 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST); 436 buffer_put_string(&msg, blob, blen); 437 buffer_put_string(&msg, data, datalen); 438 buffer_put_int(&msg, flags); 439 xfree(blob); 440 441 if (ssh_request_reply(auth, &msg, &msg) == 0) { 442 buffer_free(&msg); 443 return -1; 444 } 445 type = buffer_get_char(&msg); 446 if (agent_failed(type)) { 447 logit("Agent admitted failure to sign using the key."); 448 } else if (type != SSH2_AGENT_SIGN_RESPONSE) { 449 fatal("Bad authentication response: %d", type); 450 } else { 451 ret = 0; 452 *sigp = buffer_get_string(&msg, lenp); 453 } 454 buffer_free(&msg); 455 return ret; 456} 457 458/* Encode key for a message to the agent. */ 459 460static void 461ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment) 462{ 463 buffer_put_int(b, BN_num_bits(key->n)); 464 buffer_put_bignum(b, key->n); 465 buffer_put_bignum(b, key->e); 466 buffer_put_bignum(b, key->d); 467 /* To keep within the protocol: p < q for ssh. in SSL p > q */ 468 buffer_put_bignum(b, key->iqmp); /* ssh key->u */ 469 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */ 470 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */ 471 buffer_put_cstring(b, comment); 472} 473 474static void 475ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment) 476{ 477 buffer_put_cstring(b, key_ssh_name(key)); 478 switch (key->type) { 479 case KEY_RSA: 480 buffer_put_bignum2(b, key->rsa->n); 481 buffer_put_bignum2(b, key->rsa->e); 482 buffer_put_bignum2(b, key->rsa->d); 483 buffer_put_bignum2(b, key->rsa->iqmp); 484 buffer_put_bignum2(b, key->rsa->p); 485 buffer_put_bignum2(b, key->rsa->q); 486 break; 487 case KEY_RSA_CERT_V00: 488 case KEY_RSA_CERT: 489 if (key->cert == NULL || buffer_len(&key->cert->certblob) == 0) 490 fatal("%s: no cert/certblob", __func__); 491 buffer_put_string(b, buffer_ptr(&key->cert->certblob), 492 buffer_len(&key->cert->certblob)); 493 buffer_put_bignum2(b, key->rsa->d); 494 buffer_put_bignum2(b, key->rsa->iqmp); 495 buffer_put_bignum2(b, key->rsa->p); 496 buffer_put_bignum2(b, key->rsa->q); 497 break; 498 case KEY_DSA: 499 buffer_put_bignum2(b, key->dsa->p); 500 buffer_put_bignum2(b, key->dsa->q); 501 buffer_put_bignum2(b, key->dsa->g); 502 buffer_put_bignum2(b, key->dsa->pub_key); 503 buffer_put_bignum2(b, key->dsa->priv_key); 504 break; 505 case KEY_DSA_CERT_V00: 506 case KEY_DSA_CERT: 507 if (key->cert == NULL || buffer_len(&key->cert->certblob) == 0) 508 fatal("%s: no cert/certblob", __func__); 509 buffer_put_string(b, buffer_ptr(&key->cert->certblob), 510 buffer_len(&key->cert->certblob)); 511 buffer_put_bignum2(b, key->dsa->priv_key); 512 break; 513#ifdef OPENSSL_HAS_ECC 514 case KEY_ECDSA: 515 buffer_put_cstring(b, key_curve_nid_to_name(key->ecdsa_nid)); 516 buffer_put_ecpoint(b, EC_KEY_get0_group(key->ecdsa), 517 EC_KEY_get0_public_key(key->ecdsa)); 518 buffer_put_bignum2(b, EC_KEY_get0_private_key(key->ecdsa)); 519 break; 520 case KEY_ECDSA_CERT: 521 if (key->cert == NULL || buffer_len(&key->cert->certblob) == 0) 522 fatal("%s: no cert/certblob", __func__); 523 buffer_put_string(b, buffer_ptr(&key->cert->certblob), 524 buffer_len(&key->cert->certblob)); 525 buffer_put_bignum2(b, EC_KEY_get0_private_key(key->ecdsa)); 526 break; 527#endif 528 } 529 buffer_put_cstring(b, comment); 530} 531 532/* 533 * Adds an identity to the authentication server. This call is not meant to 534 * be used by normal applications. 535 */ 536 537int 538ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key, 539 const char *comment, u_int life, u_int confirm) 540{ 541 Buffer msg; 542 int type, constrained = (life || confirm); 543 544 buffer_init(&msg); 545 546 switch (key->type) { 547 case KEY_RSA1: 548 type = constrained ? 549 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED : 550 SSH_AGENTC_ADD_RSA_IDENTITY; 551 buffer_put_char(&msg, type); 552 ssh_encode_identity_rsa1(&msg, key->rsa, comment); 553 break; 554 case KEY_RSA: 555 case KEY_RSA_CERT: 556 case KEY_RSA_CERT_V00: 557 case KEY_DSA: 558 case KEY_DSA_CERT: 559 case KEY_DSA_CERT_V00: 560 case KEY_ECDSA: 561 case KEY_ECDSA_CERT: 562 type = constrained ? 563 SSH2_AGENTC_ADD_ID_CONSTRAINED : 564 SSH2_AGENTC_ADD_IDENTITY; 565 buffer_put_char(&msg, type); 566 ssh_encode_identity_ssh2(&msg, key, comment); 567 break; 568 default: 569 buffer_free(&msg); 570 return 0; 571 } 572 if (constrained) { 573 if (life != 0) { 574 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME); 575 buffer_put_int(&msg, life); 576 } 577 if (confirm != 0) 578 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM); 579 } 580 if (ssh_request_reply(auth, &msg, &msg) == 0) { 581 buffer_free(&msg); 582 return 0; 583 } 584 type = buffer_get_char(&msg); 585 buffer_free(&msg); 586 return decode_reply(type); 587} 588 589/* 590 * Removes an identity from the authentication server. This call is not 591 * meant to be used by normal applications. 592 */ 593 594int 595ssh_remove_identity(AuthenticationConnection *auth, Key *key) 596{ 597 Buffer msg; 598 int type; 599 u_char *blob; 600 u_int blen; 601 602 buffer_init(&msg); 603 604 if (key->type == KEY_RSA1) { 605 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY); 606 buffer_put_int(&msg, BN_num_bits(key->rsa->n)); 607 buffer_put_bignum(&msg, key->rsa->e); 608 buffer_put_bignum(&msg, key->rsa->n); 609 } else if (key_type_plain(key->type) == KEY_DSA || 610 key_type_plain(key->type) == KEY_RSA || 611 key_type_plain(key->type) == KEY_ECDSA) { 612 key_to_blob(key, &blob, &blen); 613 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY); 614 buffer_put_string(&msg, blob, blen); 615 xfree(blob); 616 } else { 617 buffer_free(&msg); 618 return 0; 619 } 620 if (ssh_request_reply(auth, &msg, &msg) == 0) { 621 buffer_free(&msg); 622 return 0; 623 } 624 type = buffer_get_char(&msg); 625 buffer_free(&msg); 626 return decode_reply(type); 627} 628 629int 630ssh_update_card(AuthenticationConnection *auth, int add, 631 const char *reader_id, const char *pin, u_int life, u_int confirm) 632{ 633 Buffer msg; 634 int type, constrained = (life || confirm); 635 636 if (add) { 637 type = constrained ? 638 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED : 639 SSH_AGENTC_ADD_SMARTCARD_KEY; 640 } else 641 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY; 642 643 buffer_init(&msg); 644 buffer_put_char(&msg, type); 645 buffer_put_cstring(&msg, reader_id); 646 buffer_put_cstring(&msg, pin); 647 648 if (constrained) { 649 if (life != 0) { 650 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME); 651 buffer_put_int(&msg, life); 652 } 653 if (confirm != 0) 654 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM); 655 } 656 657 if (ssh_request_reply(auth, &msg, &msg) == 0) { 658 buffer_free(&msg); 659 return 0; 660 } 661 type = buffer_get_char(&msg); 662 buffer_free(&msg); 663 return decode_reply(type); 664} 665 666/* 667 * Removes all identities from the agent. This call is not meant to be used 668 * by normal applications. 669 */ 670 671int 672ssh_remove_all_identities(AuthenticationConnection *auth, int version) 673{ 674 Buffer msg; 675 int type; 676 int code = (version==1) ? 677 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES : 678 SSH2_AGENTC_REMOVE_ALL_IDENTITIES; 679 680 buffer_init(&msg); 681 buffer_put_char(&msg, code); 682 683 if (ssh_request_reply(auth, &msg, &msg) == 0) { 684 buffer_free(&msg); 685 return 0; 686 } 687 type = buffer_get_char(&msg); 688 buffer_free(&msg); 689 return decode_reply(type); 690} 691 692int 693decode_reply(int type) 694{ 695 switch (type) { 696 case SSH_AGENT_FAILURE: 697 case SSH_COM_AGENT2_FAILURE: 698 case SSH2_AGENT_FAILURE: 699 logit("SSH_AGENT_FAILURE"); 700 return 0; 701 case SSH_AGENT_SUCCESS: 702 return 1; 703 default: 704 fatal("Bad response from authentication agent: %d", type); 705 } 706 /* NOTREACHED */ 707 return 0; 708} 709