1 /* 2 * Copyright (c) 2000 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #include "includes.h" 26 RCSID("$OpenBSD: sshconnect2.c,v 1.108 2002/11/21 22:45:31 markus Exp $"); 27 28 #include "ssh.h" 29 #include "ssh2.h" 30 #include "xmalloc.h" 31 #include "buffer.h" 32 #include "packet.h" 33 #include "compat.h" 34 #include "bufaux.h" 35 #include "cipher.h" 36 #include "kex.h" 37 #include "myproposal.h" 38 #include "sshconnect.h" 39 #include "authfile.h" 40 #include "dh.h" 41 #include "authfd.h" 42 #include "log.h" 43 #include "readconf.h" 44 #include "readpass.h" 45 #include "match.h" 46 #include "dispatch.h" 47 #include "canohost.h" 48 #include "msg.h" 49 #include "pathnames.h" 50 51 /* import */ 52 extern char *client_version_string; 53 extern char *server_version_string; 54 extern Options options; 55 56 /* 57 * SSH2 key exchange 58 */ 59 60 u_char *session_id2 = NULL; 61 int session_id2_len = 0; 62 63 char *xxx_host; 64 struct sockaddr *xxx_hostaddr; 65 66 Kex *xxx_kex = NULL; 67 68 static int 69 verify_host_key_callback(Key *hostkey) 70 { 71 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 72 fatal("Host key verification failed."); 73 return 0; 74 } 75 76 void 77 ssh_kex2(char *host, struct sockaddr *hostaddr) 78 { 79 Kex *kex; 80 81 xxx_host = host; 82 xxx_hostaddr = hostaddr; 83 84 if (options.ciphers == (char *)-1) { 85 log("No valid ciphers for protocol version 2 given, using defaults."); 86 options.ciphers = NULL; 87 } 88 if (options.ciphers != NULL) { 89 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 90 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 91 } 92 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 93 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 94 myproposal[PROPOSAL_ENC_ALGS_STOC] = 95 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 96 if (options.compression) { 97 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 98 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none"; 99 } else { 100 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 101 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib"; 102 } 103 if (options.macs != NULL) { 104 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 105 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 106 } 107 if (options.hostkeyalgorithms != NULL) 108 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 109 options.hostkeyalgorithms; 110 111 /* start key exchange */ 112 kex = kex_setup(myproposal); 113 kex->client_version_string=client_version_string; 114 kex->server_version_string=server_version_string; 115 kex->verify_host_key=&verify_host_key_callback; 116 117 xxx_kex = kex; 118 119 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 120 121 session_id2 = kex->session_id; 122 session_id2_len = kex->session_id_len; 123 124 #ifdef DEBUG_KEXDH 125 /* send 1st encrypted/maced/compressed message */ 126 packet_start(SSH2_MSG_IGNORE); 127 packet_put_cstring("markus"); 128 packet_send(); 129 packet_write_wait(); 130 #endif 131 } 132 133 /* 134 * Authenticate user 135 */ 136 137 typedef struct Authctxt Authctxt; 138 typedef struct Authmethod Authmethod; 139 140 typedef int sign_cb_fn( 141 Authctxt *authctxt, Key *key, 142 u_char **sigp, u_int *lenp, u_char *data, u_int datalen); 143 144 struct Authctxt { 145 const char *server_user; 146 const char *local_user; 147 const char *host; 148 const char *service; 149 Authmethod *method; 150 int success; 151 char *authlist; 152 /* pubkey */ 153 Key *last_key; 154 sign_cb_fn *last_key_sign; 155 int last_key_hint; 156 AuthenticationConnection *agent; 157 /* hostbased */ 158 Sensitive *sensitive; 159 /* kbd-interactive */ 160 int info_req_seen; 161 }; 162 struct Authmethod { 163 char *name; /* string to compare against server's list */ 164 int (*userauth)(Authctxt *authctxt); 165 int *enabled; /* flag in option struct that enables method */ 166 int *batch_flag; /* flag in option struct that disables method */ 167 }; 168 169 void input_userauth_success(int, u_int32_t, void *); 170 void input_userauth_failure(int, u_int32_t, void *); 171 void input_userauth_banner(int, u_int32_t, void *); 172 void input_userauth_error(int, u_int32_t, void *); 173 void input_userauth_info_req(int, u_int32_t, void *); 174 void input_userauth_pk_ok(int, u_int32_t, void *); 175 void input_userauth_passwd_changereq(int, u_int32_t, void *); 176 177 int userauth_none(Authctxt *); 178 int userauth_pubkey(Authctxt *); 179 int userauth_passwd(Authctxt *); 180 int userauth_kbdint(Authctxt *); 181 int userauth_hostbased(Authctxt *); 182 183 void userauth(Authctxt *, char *); 184 185 static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *); 186 static void clear_auth_state(Authctxt *); 187 188 static Authmethod *authmethod_get(char *authlist); 189 static Authmethod *authmethod_lookup(const char *name); 190 static char *authmethods_get(void); 191 192 Authmethod authmethods[] = { 193 {"hostbased", 194 userauth_hostbased, 195 &options.hostbased_authentication, 196 NULL}, 197 {"publickey", 198 userauth_pubkey, 199 &options.pubkey_authentication, 200 NULL}, 201 {"keyboard-interactive", 202 userauth_kbdint, 203 &options.kbd_interactive_authentication, 204 &options.batch_mode}, 205 {"password", 206 userauth_passwd, 207 &options.password_authentication, 208 &options.batch_mode}, 209 {"none", 210 userauth_none, 211 NULL, 212 NULL}, 213 {NULL, NULL, NULL, NULL} 214 }; 215 216 void 217 ssh_userauth2(const char *local_user, const char *server_user, char *host, 218 Sensitive *sensitive) 219 { 220 Authctxt authctxt; 221 int type; 222 223 if (options.challenge_response_authentication) 224 options.kbd_interactive_authentication = 1; 225 226 packet_start(SSH2_MSG_SERVICE_REQUEST); 227 packet_put_cstring("ssh-userauth"); 228 packet_send(); 229 debug("SSH2_MSG_SERVICE_REQUEST sent"); 230 packet_write_wait(); 231 type = packet_read(); 232 if (type != SSH2_MSG_SERVICE_ACCEPT) 233 fatal("Server denied authentication request: %d", type); 234 if (packet_remaining() > 0) { 235 char *reply = packet_get_string(NULL); 236 debug2("service_accept: %s", reply); 237 xfree(reply); 238 } else { 239 debug("buggy server: service_accept w/o service"); 240 } 241 packet_check_eom(); 242 debug("SSH2_MSG_SERVICE_ACCEPT received"); 243 244 if (options.preferred_authentications == NULL) 245 options.preferred_authentications = authmethods_get(); 246 247 /* setup authentication context */ 248 memset(&authctxt, 0, sizeof(authctxt)); 249 authctxt.agent = ssh_get_authentication_connection(); 250 authctxt.server_user = server_user; 251 authctxt.local_user = local_user; 252 authctxt.host = host; 253 authctxt.service = "ssh-connection"; /* service name */ 254 authctxt.success = 0; 255 authctxt.method = authmethod_lookup("none"); 256 authctxt.authlist = NULL; 257 authctxt.sensitive = sensitive; 258 authctxt.info_req_seen = 0; 259 if (authctxt.method == NULL) 260 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 261 262 /* initial userauth request */ 263 userauth_none(&authctxt); 264 265 dispatch_init(&input_userauth_error); 266 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 267 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 268 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 269 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 270 271 if (authctxt.agent != NULL) 272 ssh_close_authentication_connection(authctxt.agent); 273 274 debug("ssh-userauth2 successful: method %s", authctxt.method->name); 275 } 276 void 277 userauth(Authctxt *authctxt, char *authlist) 278 { 279 if (authlist == NULL) { 280 authlist = authctxt->authlist; 281 } else { 282 if (authctxt->authlist) 283 xfree(authctxt->authlist); 284 authctxt->authlist = authlist; 285 } 286 for (;;) { 287 Authmethod *method = authmethod_get(authlist); 288 if (method == NULL) 289 fatal("Permission denied (%s).", authlist); 290 authctxt->method = method; 291 if (method->userauth(authctxt) != 0) { 292 debug2("we sent a %s packet, wait for reply", method->name); 293 break; 294 } else { 295 debug2("we did not send a packet, disable method"); 296 method->enabled = NULL; 297 } 298 } 299 } 300 301 void 302 input_userauth_error(int type, u_int32_t seq, void *ctxt) 303 { 304 fatal("input_userauth_error: bad message during authentication: " 305 "type %d", type); 306 } 307 308 void 309 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 310 { 311 char *msg, *lang; 312 debug3("input_userauth_banner"); 313 msg = packet_get_string(NULL); 314 lang = packet_get_string(NULL); 315 fprintf(stderr, "%s", msg); 316 xfree(msg); 317 xfree(lang); 318 } 319 320 void 321 input_userauth_success(int type, u_int32_t seq, void *ctxt) 322 { 323 Authctxt *authctxt = ctxt; 324 if (authctxt == NULL) 325 fatal("input_userauth_success: no authentication context"); 326 if (authctxt->authlist) 327 xfree(authctxt->authlist); 328 clear_auth_state(authctxt); 329 authctxt->success = 1; /* break out */ 330 } 331 332 void 333 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 334 { 335 Authctxt *authctxt = ctxt; 336 char *authlist = NULL; 337 int partial; 338 339 if (authctxt == NULL) 340 fatal("input_userauth_failure: no authentication context"); 341 342 authlist = packet_get_string(NULL); 343 partial = packet_get_char(); 344 packet_check_eom(); 345 346 if (partial != 0) 347 log("Authenticated with partial success."); 348 debug("authentications that can continue: %s", authlist); 349 350 clear_auth_state(authctxt); 351 userauth(authctxt, authlist); 352 } 353 void 354 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 355 { 356 Authctxt *authctxt = ctxt; 357 Key *key = NULL; 358 Buffer b; 359 int pktype, sent = 0; 360 u_int alen, blen; 361 char *pkalg, *fp; 362 u_char *pkblob; 363 364 if (authctxt == NULL) 365 fatal("input_userauth_pk_ok: no authentication context"); 366 if (datafellows & SSH_BUG_PKOK) { 367 /* this is similar to SSH_BUG_PKAUTH */ 368 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 369 pkblob = packet_get_string(&blen); 370 buffer_init(&b); 371 buffer_append(&b, pkblob, blen); 372 pkalg = buffer_get_string(&b, &alen); 373 buffer_free(&b); 374 } else { 375 pkalg = packet_get_string(&alen); 376 pkblob = packet_get_string(&blen); 377 } 378 packet_check_eom(); 379 380 debug("input_userauth_pk_ok: pkalg %s blen %u lastkey %p hint %d", 381 pkalg, blen, authctxt->last_key, authctxt->last_key_hint); 382 383 do { 384 if (authctxt->last_key == NULL || 385 authctxt->last_key_sign == NULL) { 386 debug("no last key or no sign cb"); 387 break; 388 } 389 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 390 debug("unknown pkalg %s", pkalg); 391 break; 392 } 393 if ((key = key_from_blob(pkblob, blen)) == NULL) { 394 debug("no key from blob. pkalg %s", pkalg); 395 break; 396 } 397 if (key->type != pktype) { 398 error("input_userauth_pk_ok: type mismatch " 399 "for decoded key (received %d, expected %d)", 400 key->type, pktype); 401 break; 402 } 403 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 404 debug2("input_userauth_pk_ok: fp %s", fp); 405 xfree(fp); 406 if (!key_equal(key, authctxt->last_key)) { 407 debug("key != last_key"); 408 break; 409 } 410 sent = sign_and_send_pubkey(authctxt, key, 411 authctxt->last_key_sign); 412 } while (0); 413 414 if (key != NULL) 415 key_free(key); 416 xfree(pkalg); 417 xfree(pkblob); 418 419 /* unregister */ 420 clear_auth_state(authctxt); 421 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); 422 423 /* try another method if we did not send a packet */ 424 if (sent == 0) 425 userauth(authctxt, NULL); 426 427 } 428 429 int 430 userauth_none(Authctxt *authctxt) 431 { 432 /* initial userauth request */ 433 packet_start(SSH2_MSG_USERAUTH_REQUEST); 434 packet_put_cstring(authctxt->server_user); 435 packet_put_cstring(authctxt->service); 436 packet_put_cstring(authctxt->method->name); 437 packet_send(); 438 return 1; 439 } 440 441 int 442 userauth_passwd(Authctxt *authctxt) 443 { 444 static int attempt = 0; 445 char prompt[150]; 446 char *password; 447 448 if (attempt++ >= options.number_of_password_prompts) 449 return 0; 450 451 if (attempt != 1) 452 error("Permission denied, please try again."); 453 454 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 455 authctxt->server_user, authctxt->host); 456 password = read_passphrase(prompt, 0); 457 packet_start(SSH2_MSG_USERAUTH_REQUEST); 458 packet_put_cstring(authctxt->server_user); 459 packet_put_cstring(authctxt->service); 460 packet_put_cstring(authctxt->method->name); 461 packet_put_char(0); 462 packet_put_cstring(password); 463 memset(password, 0, strlen(password)); 464 xfree(password); 465 packet_add_padding(64); 466 packet_send(); 467 468 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 469 &input_userauth_passwd_changereq); 470 471 return 1; 472 } 473 /* 474 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 475 */ 476 void 477 input_userauth_passwd_changereq(int type, uint32_t seqnr, void *ctxt) 478 { 479 Authctxt *authctxt = ctxt; 480 char *info, *lang, *password = NULL, *retype = NULL; 481 char prompt[150]; 482 483 debug2("input_userauth_passwd_changereq"); 484 485 if (authctxt == NULL) 486 fatal("input_userauth_passwd_changereq: " 487 "no authentication context"); 488 489 info = packet_get_string(NULL); 490 lang = packet_get_string(NULL); 491 if (strlen(info) > 0) 492 log("%s", info); 493 xfree(info); 494 xfree(lang); 495 packet_start(SSH2_MSG_USERAUTH_REQUEST); 496 packet_put_cstring(authctxt->server_user); 497 packet_put_cstring(authctxt->service); 498 packet_put_cstring(authctxt->method->name); 499 packet_put_char(1); /* additional info */ 500 snprintf(prompt, sizeof(prompt), 501 "Enter %.30s@%.128s's old password: ", 502 authctxt->server_user, authctxt->host); 503 password = read_passphrase(prompt, 0); 504 packet_put_cstring(password); 505 memset(password, 0, strlen(password)); 506 xfree(password); 507 password = NULL; 508 while (password == NULL) { 509 snprintf(prompt, sizeof(prompt), 510 "Enter %.30s@%.128s's new password: ", 511 authctxt->server_user, authctxt->host); 512 password = read_passphrase(prompt, RP_ALLOW_EOF); 513 if (password == NULL) { 514 /* bail out */ 515 return; 516 } 517 snprintf(prompt, sizeof(prompt), 518 "Retype %.30s@%.128s's new password: ", 519 authctxt->server_user, authctxt->host); 520 retype = read_passphrase(prompt, 0); 521 if (strcmp(password, retype) != 0) { 522 memset(password, 0, strlen(password)); 523 xfree(password); 524 log("Mismatch; try again, EOF to quit."); 525 password = NULL; 526 } 527 memset(retype, 0, strlen(retype)); 528 xfree(retype); 529 } 530 packet_put_cstring(password); 531 memset(password, 0, strlen(password)); 532 xfree(password); 533 packet_add_padding(64); 534 packet_send(); 535 536 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 537 &input_userauth_passwd_changereq); 538 } 539 540 static void 541 clear_auth_state(Authctxt *authctxt) 542 { 543 /* XXX clear authentication state */ 544 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL); 545 546 if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { 547 debug3("clear_auth_state: key_free %p", authctxt->last_key); 548 key_free(authctxt->last_key); 549 } 550 authctxt->last_key = NULL; 551 authctxt->last_key_hint = -2; 552 authctxt->last_key_sign = NULL; 553 } 554 555 static int 556 sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) 557 { 558 Buffer b; 559 u_char *blob, *signature; 560 u_int bloblen, slen; 561 int skip = 0; 562 int ret = -1; 563 int have_sig = 1; 564 565 debug3("sign_and_send_pubkey"); 566 567 if (key_to_blob(k, &blob, &bloblen) == 0) { 568 /* we cannot handle this key */ 569 debug3("sign_and_send_pubkey: cannot handle key"); 570 return 0; 571 } 572 /* data to be signed */ 573 buffer_init(&b); 574 if (datafellows & SSH_OLD_SESSIONID) { 575 buffer_append(&b, session_id2, session_id2_len); 576 skip = session_id2_len; 577 } else { 578 buffer_put_string(&b, session_id2, session_id2_len); 579 skip = buffer_len(&b); 580 } 581 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 582 buffer_put_cstring(&b, authctxt->server_user); 583 buffer_put_cstring(&b, 584 datafellows & SSH_BUG_PKSERVICE ? 585 "ssh-userauth" : 586 authctxt->service); 587 if (datafellows & SSH_BUG_PKAUTH) { 588 buffer_put_char(&b, have_sig); 589 } else { 590 buffer_put_cstring(&b, authctxt->method->name); 591 buffer_put_char(&b, have_sig); 592 buffer_put_cstring(&b, key_ssh_name(k)); 593 } 594 buffer_put_string(&b, blob, bloblen); 595 596 /* generate signature */ 597 ret = (*sign_callback)(authctxt, k, &signature, &slen, 598 buffer_ptr(&b), buffer_len(&b)); 599 if (ret == -1) { 600 xfree(blob); 601 buffer_free(&b); 602 return 0; 603 } 604 #ifdef DEBUG_PK 605 buffer_dump(&b); 606 #endif 607 if (datafellows & SSH_BUG_PKSERVICE) { 608 buffer_clear(&b); 609 buffer_append(&b, session_id2, session_id2_len); 610 skip = session_id2_len; 611 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 612 buffer_put_cstring(&b, authctxt->server_user); 613 buffer_put_cstring(&b, authctxt->service); 614 buffer_put_cstring(&b, authctxt->method->name); 615 buffer_put_char(&b, have_sig); 616 if (!(datafellows & SSH_BUG_PKAUTH)) 617 buffer_put_cstring(&b, key_ssh_name(k)); 618 buffer_put_string(&b, blob, bloblen); 619 } 620 xfree(blob); 621 622 /* append signature */ 623 buffer_put_string(&b, signature, slen); 624 xfree(signature); 625 626 /* skip session id and packet type */ 627 if (buffer_len(&b) < skip + 1) 628 fatal("userauth_pubkey: internal error"); 629 buffer_consume(&b, skip + 1); 630 631 /* put remaining data from buffer into packet */ 632 packet_start(SSH2_MSG_USERAUTH_REQUEST); 633 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 634 buffer_free(&b); 635 packet_send(); 636 637 return 1; 638 } 639 640 static int 641 send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, 642 int hint) 643 { 644 u_char *blob; 645 u_int bloblen, have_sig = 0; 646 647 debug3("send_pubkey_test"); 648 649 if (key_to_blob(k, &blob, &bloblen) == 0) { 650 /* we cannot handle this key */ 651 debug3("send_pubkey_test: cannot handle key"); 652 return 0; 653 } 654 /* register callback for USERAUTH_PK_OK message */ 655 authctxt->last_key_sign = sign_callback; 656 authctxt->last_key_hint = hint; 657 authctxt->last_key = k; 658 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 659 660 packet_start(SSH2_MSG_USERAUTH_REQUEST); 661 packet_put_cstring(authctxt->server_user); 662 packet_put_cstring(authctxt->service); 663 packet_put_cstring(authctxt->method->name); 664 packet_put_char(have_sig); 665 if (!(datafellows & SSH_BUG_PKAUTH)) 666 packet_put_cstring(key_ssh_name(k)); 667 packet_put_string(blob, bloblen); 668 xfree(blob); 669 packet_send(); 670 return 1; 671 } 672 673 static Key * 674 load_identity_file(char *filename) 675 { 676 Key *private; 677 char prompt[300], *passphrase; 678 int quit, i; 679 struct stat st; 680 681 if (stat(filename, &st) < 0) { 682 debug3("no such identity: %s", filename); 683 return NULL; 684 } 685 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 686 if (private == NULL) { 687 if (options.batch_mode) 688 return NULL; 689 snprintf(prompt, sizeof prompt, 690 "Enter passphrase for key '%.100s': ", filename); 691 for (i = 0; i < options.number_of_password_prompts; i++) { 692 passphrase = read_passphrase(prompt, 0); 693 if (strcmp(passphrase, "") != 0) { 694 private = key_load_private_type(KEY_UNSPEC, filename, 695 passphrase, NULL); 696 quit = 0; 697 } else { 698 debug2("no passphrase given, try next key"); 699 quit = 1; 700 } 701 memset(passphrase, 0, strlen(passphrase)); 702 xfree(passphrase); 703 if (private != NULL || quit) 704 break; 705 debug2("bad passphrase given, try again..."); 706 } 707 } 708 return private; 709 } 710 711 static int 712 identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 713 u_char *data, u_int datalen) 714 { 715 Key *private; 716 int idx, ret; 717 718 idx = authctxt->last_key_hint; 719 if (idx < 0) 720 return -1; 721 722 /* private key is stored in external hardware */ 723 if (options.identity_keys[idx]->flags & KEY_FLAG_EXT) 724 return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen); 725 726 private = load_identity_file(options.identity_files[idx]); 727 if (private == NULL) 728 return -1; 729 ret = key_sign(private, sigp, lenp, data, datalen); 730 key_free(private); 731 return ret; 732 } 733 734 static int 735 agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 736 u_char *data, u_int datalen) 737 { 738 return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); 739 } 740 741 static int 742 key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 743 u_char *data, u_int datalen) 744 { 745 return key_sign(key, sigp, lenp, data, datalen); 746 } 747 748 static int 749 userauth_pubkey_agent(Authctxt *authctxt) 750 { 751 static int called = 0; 752 int ret = 0; 753 char *comment; 754 Key *k; 755 756 if (called == 0) { 757 if (ssh_get_num_identities(authctxt->agent, 2) == 0) 758 debug2("userauth_pubkey_agent: no keys at all"); 759 called = 1; 760 } 761 k = ssh_get_next_identity(authctxt->agent, &comment, 2); 762 if (k == NULL) { 763 debug2("userauth_pubkey_agent: no more keys"); 764 } else { 765 debug("userauth_pubkey_agent: testing agent key %s", comment); 766 xfree(comment); 767 ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); 768 if (ret == 0) 769 key_free(k); 770 } 771 if (ret == 0) 772 debug2("userauth_pubkey_agent: no message sent"); 773 return ret; 774 } 775 776 int 777 userauth_pubkey(Authctxt *authctxt) 778 { 779 static int idx = 0; 780 int sent = 0; 781 Key *key; 782 char *filename; 783 784 if (authctxt->agent != NULL) { 785 do { 786 sent = userauth_pubkey_agent(authctxt); 787 } while (!sent && authctxt->agent->howmany > 0); 788 } 789 while (!sent && idx < options.num_identity_files) { 790 key = options.identity_keys[idx]; 791 filename = options.identity_files[idx]; 792 if (key == NULL) { 793 debug("try privkey: %s", filename); 794 key = load_identity_file(filename); 795 if (key != NULL) { 796 sent = sign_and_send_pubkey(authctxt, key, 797 key_sign_cb); 798 key_free(key); 799 } 800 } else if (key->type != KEY_RSA1) { 801 debug("try pubkey: %s", filename); 802 sent = send_pubkey_test(authctxt, key, 803 identity_sign_cb, idx); 804 } 805 idx++; 806 } 807 return sent; 808 } 809 810 /* 811 * Send userauth request message specifying keyboard-interactive method. 812 */ 813 int 814 userauth_kbdint(Authctxt *authctxt) 815 { 816 static int attempt = 0; 817 818 if (attempt++ >= options.number_of_password_prompts) 819 return 0; 820 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 821 if (attempt > 1 && !authctxt->info_req_seen) { 822 debug3("userauth_kbdint: disable: no info_req_seen"); 823 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 824 return 0; 825 } 826 827 debug2("userauth_kbdint"); 828 packet_start(SSH2_MSG_USERAUTH_REQUEST); 829 packet_put_cstring(authctxt->server_user); 830 packet_put_cstring(authctxt->service); 831 packet_put_cstring(authctxt->method->name); 832 packet_put_cstring(""); /* lang */ 833 packet_put_cstring(options.kbd_interactive_devices ? 834 options.kbd_interactive_devices : ""); 835 packet_send(); 836 837 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 838 return 1; 839 } 840 841 /* 842 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 843 */ 844 void 845 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 846 { 847 Authctxt *authctxt = ctxt; 848 char *name, *inst, *lang, *prompt, *response; 849 u_int num_prompts, i; 850 int echo = 0; 851 852 debug2("input_userauth_info_req"); 853 854 if (authctxt == NULL) 855 fatal("input_userauth_info_req: no authentication context"); 856 857 authctxt->info_req_seen = 1; 858 859 name = packet_get_string(NULL); 860 inst = packet_get_string(NULL); 861 lang = packet_get_string(NULL); 862 if (strlen(name) > 0) 863 log("%s", name); 864 if (strlen(inst) > 0) 865 log("%s", inst); 866 xfree(name); 867 xfree(inst); 868 xfree(lang); 869 870 num_prompts = packet_get_int(); 871 /* 872 * Begin to build info response packet based on prompts requested. 873 * We commit to providing the correct number of responses, so if 874 * further on we run into a problem that prevents this, we have to 875 * be sure and clean this up and send a correct error response. 876 */ 877 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 878 packet_put_int(num_prompts); 879 880 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 881 for (i = 0; i < num_prompts; i++) { 882 prompt = packet_get_string(NULL); 883 echo = packet_get_char(); 884 885 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 886 887 packet_put_cstring(response); 888 memset(response, 0, strlen(response)); 889 xfree(response); 890 xfree(prompt); 891 } 892 packet_check_eom(); /* done with parsing incoming message. */ 893 894 packet_add_padding(64); 895 packet_send(); 896 } 897 898 static int 899 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 900 u_char *data, u_int datalen) 901 { 902 Buffer b; 903 struct stat st; 904 pid_t pid; 905 int to[2], from[2], status, version = 2; 906 907 debug("ssh_keysign called"); 908 909 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 910 error("ssh_keysign: no installed: %s", strerror(errno)); 911 return -1; 912 } 913 if (fflush(stdout) != 0) 914 error("ssh_keysign: fflush: %s", strerror(errno)); 915 if (pipe(to) < 0) { 916 error("ssh_keysign: pipe: %s", strerror(errno)); 917 return -1; 918 } 919 if (pipe(from) < 0) { 920 error("ssh_keysign: pipe: %s", strerror(errno)); 921 return -1; 922 } 923 if ((pid = fork()) < 0) { 924 error("ssh_keysign: fork: %s", strerror(errno)); 925 return -1; 926 } 927 if (pid == 0) { 928 seteuid(getuid()); 929 setuid(getuid()); 930 close(from[0]); 931 if (dup2(from[1], STDOUT_FILENO) < 0) 932 fatal("ssh_keysign: dup2: %s", strerror(errno)); 933 close(to[1]); 934 if (dup2(to[0], STDIN_FILENO) < 0) 935 fatal("ssh_keysign: dup2: %s", strerror(errno)); 936 close(from[1]); 937 close(to[0]); 938 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 939 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 940 strerror(errno)); 941 } 942 close(from[1]); 943 close(to[0]); 944 945 buffer_init(&b); 946 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 947 buffer_put_string(&b, data, datalen); 948 msg_send(to[1], version, &b); 949 950 if (msg_recv(from[0], &b) < 0) { 951 error("ssh_keysign: no reply"); 952 buffer_clear(&b); 953 return -1; 954 } 955 close(from[0]); 956 close(to[1]); 957 958 while (waitpid(pid, &status, 0) < 0) 959 if (errno != EINTR) 960 break; 961 962 if (buffer_get_char(&b) != version) { 963 error("ssh_keysign: bad version"); 964 buffer_clear(&b); 965 return -1; 966 } 967 *sigp = buffer_get_string(&b, lenp); 968 buffer_clear(&b); 969 970 return 0; 971 } 972 973 int 974 userauth_hostbased(Authctxt *authctxt) 975 { 976 Key *private = NULL; 977 Sensitive *sensitive = authctxt->sensitive; 978 Buffer b; 979 u_char *signature, *blob; 980 char *chost, *pkalg, *p; 981 const char *service; 982 u_int blen, slen; 983 int ok, i, len, found = 0; 984 985 /* check for a useful key */ 986 for (i = 0; i < sensitive->nkeys; i++) { 987 private = sensitive->keys[i]; 988 if (private && private->type != KEY_RSA1) { 989 found = 1; 990 /* we take and free the key */ 991 sensitive->keys[i] = NULL; 992 break; 993 } 994 } 995 if (!found) { 996 debug("userauth_hostbased: no more client hostkeys"); 997 return 0; 998 } 999 if (key_to_blob(private, &blob, &blen) == 0) { 1000 key_free(private); 1001 return 0; 1002 } 1003 /* figure out a name for the client host */ 1004 p = get_local_name(packet_get_connection_in()); 1005 if (p == NULL) { 1006 error("userauth_hostbased: cannot get local ipaddr/name"); 1007 key_free(private); 1008 return 0; 1009 } 1010 len = strlen(p) + 2; 1011 chost = xmalloc(len); 1012 strlcpy(chost, p, len); 1013 strlcat(chost, ".", len); 1014 debug2("userauth_hostbased: chost %s", chost); 1015 1016 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1017 authctxt->service; 1018 pkalg = xstrdup(key_ssh_name(private)); 1019 buffer_init(&b); 1020 /* construct data */ 1021 buffer_put_string(&b, session_id2, session_id2_len); 1022 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1023 buffer_put_cstring(&b, authctxt->server_user); 1024 buffer_put_cstring(&b, service); 1025 buffer_put_cstring(&b, authctxt->method->name); 1026 buffer_put_cstring(&b, pkalg); 1027 buffer_put_string(&b, blob, blen); 1028 buffer_put_cstring(&b, chost); 1029 buffer_put_cstring(&b, authctxt->local_user); 1030 #ifdef DEBUG_PK 1031 buffer_dump(&b); 1032 #endif 1033 if (sensitive->external_keysign) 1034 ok = ssh_keysign(private, &signature, &slen, 1035 buffer_ptr(&b), buffer_len(&b)); 1036 else 1037 ok = key_sign(private, &signature, &slen, 1038 buffer_ptr(&b), buffer_len(&b)); 1039 key_free(private); 1040 buffer_free(&b); 1041 if (ok != 0) { 1042 error("key_sign failed"); 1043 xfree(chost); 1044 xfree(pkalg); 1045 return 0; 1046 } 1047 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1048 packet_put_cstring(authctxt->server_user); 1049 packet_put_cstring(authctxt->service); 1050 packet_put_cstring(authctxt->method->name); 1051 packet_put_cstring(pkalg); 1052 packet_put_string(blob, blen); 1053 packet_put_cstring(chost); 1054 packet_put_cstring(authctxt->local_user); 1055 packet_put_string(signature, slen); 1056 memset(signature, 's', slen); 1057 xfree(signature); 1058 xfree(chost); 1059 xfree(pkalg); 1060 1061 packet_send(); 1062 return 1; 1063 } 1064 1065 /* find auth method */ 1066 1067 /* 1068 * given auth method name, if configurable options permit this method fill 1069 * in auth_ident field and return true, otherwise return false. 1070 */ 1071 static int 1072 authmethod_is_enabled(Authmethod *method) 1073 { 1074 if (method == NULL) 1075 return 0; 1076 /* return false if options indicate this method is disabled */ 1077 if (method->enabled == NULL || *method->enabled == 0) 1078 return 0; 1079 /* return false if batch mode is enabled but method needs interactive mode */ 1080 if (method->batch_flag != NULL && *method->batch_flag != 0) 1081 return 0; 1082 return 1; 1083 } 1084 1085 static Authmethod * 1086 authmethod_lookup(const char *name) 1087 { 1088 Authmethod *method = NULL; 1089 if (name != NULL) 1090 for (method = authmethods; method->name != NULL; method++) 1091 if (strcmp(name, method->name) == 0) 1092 return method; 1093 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1094 return NULL; 1095 } 1096 1097 /* XXX internal state */ 1098 static Authmethod *current = NULL; 1099 static char *supported = NULL; 1100 static char *preferred = NULL; 1101 1102 /* 1103 * Given the authentication method list sent by the server, return the 1104 * next method we should try. If the server initially sends a nil list, 1105 * use a built-in default list. 1106 */ 1107 static Authmethod * 1108 authmethod_get(char *authlist) 1109 { 1110 1111 char *name = NULL; 1112 u_int next; 1113 1114 /* Use a suitable default if we're passed a nil list. */ 1115 if (authlist == NULL || strlen(authlist) == 0) 1116 authlist = options.preferred_authentications; 1117 1118 if (supported == NULL || strcmp(authlist, supported) != 0) { 1119 debug3("start over, passed a different list %s", authlist); 1120 if (supported != NULL) 1121 xfree(supported); 1122 supported = xstrdup(authlist); 1123 preferred = options.preferred_authentications; 1124 debug3("preferred %s", preferred); 1125 current = NULL; 1126 } else if (current != NULL && authmethod_is_enabled(current)) 1127 return current; 1128 1129 for (;;) { 1130 if ((name = match_list(preferred, supported, &next)) == NULL) { 1131 debug("no more auth methods to try"); 1132 current = NULL; 1133 return NULL; 1134 } 1135 preferred += next; 1136 debug3("authmethod_lookup %s", name); 1137 debug3("remaining preferred: %s", preferred); 1138 if ((current = authmethod_lookup(name)) != NULL && 1139 authmethod_is_enabled(current)) { 1140 debug3("authmethod_is_enabled %s", name); 1141 debug("next auth method to try is %s", name); 1142 return current; 1143 } 1144 } 1145 } 1146 1147 static char * 1148 authmethods_get(void) 1149 { 1150 Authmethod *method = NULL; 1151 Buffer b; 1152 char *list; 1153 1154 buffer_init(&b); 1155 for (method = authmethods; method->name != NULL; method++) { 1156 if (authmethod_is_enabled(method)) { 1157 if (buffer_len(&b) > 0) 1158 buffer_append(&b, ",", 1); 1159 buffer_append(&b, method->name, strlen(method->name)); 1160 } 1161 } 1162 buffer_append(&b, "\0", 1); 1163 list = xstrdup(buffer_ptr(&b)); 1164 buffer_free(&b); 1165 return list; 1166 } 1167