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 1.104 2002/06/19 00:27:55 deraadt Exp $"); 27 RCSID("$FreeBSD$"); 28 29 #include "ssh.h" 30 #include "ssh2.h" 31 #include "xmalloc.h" 32 #include "buffer.h" 33 #include "packet.h" 34 #include "compat.h" 35 #include "bufaux.h" 36 #include "cipher.h" 37 #include "kex.h" 38 #include "myproposal.h" 39 #include "sshconnect.h" 40 #include "authfile.h" 41 #include "dh.h" 42 #include "authfd.h" 43 #include "log.h" 44 #include "readconf.h" 45 #include "readpass.h" 46 #include "match.h" 47 #include "dispatch.h" 48 #include "canohost.h" 49 #include "msg.h" 50 #include "pathnames.h" 51 52 /* import */ 53 extern char *client_version_string; 54 extern char *server_version_string; 55 extern Options options; 56 57 /* 58 * SSH2 key exchange 59 */ 60 61 u_char *session_id2 = NULL; 62 int session_id2_len = 0; 63 64 char *xxx_host; 65 struct sockaddr *xxx_hostaddr; 66 67 Kex *xxx_kex = NULL; 68 69 static int 70 verify_host_key_callback(Key *hostkey) 71 { 72 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 73 fatal("Host key verification failed."); 74 return 0; 75 } 76 77 void 78 ssh_kex2(char *host, struct sockaddr *hostaddr) 79 { 80 Kex *kex; 81 82 xxx_host = host; 83 xxx_hostaddr = hostaddr; 84 85 if (options.ciphers == (char *)-1) { 86 log("No valid ciphers for protocol version 2 given, using defaults."); 87 options.ciphers = NULL; 88 } 89 if (options.ciphers != NULL) { 90 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 91 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 92 } 93 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 94 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 95 myproposal[PROPOSAL_ENC_ALGS_STOC] = 96 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 97 if (options.compression) { 98 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 99 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; 100 } else { 101 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 102 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 103 } 104 if (options.macs != NULL) { 105 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 106 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 107 } 108 if (options.hostkeyalgorithms != NULL) 109 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 110 options.hostkeyalgorithms; 111 112 /* start key exchange */ 113 kex = kex_setup(myproposal); 114 kex->client_version_string=client_version_string; 115 kex->server_version_string=server_version_string; 116 kex->verify_host_key=&verify_host_key_callback; 117 118 xxx_kex = kex; 119 120 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 121 122 session_id2 = kex->session_id; 123 session_id2_len = kex->session_id_len; 124 125 #ifdef DEBUG_KEXDH 126 /* send 1st encrypted/maced/compressed message */ 127 packet_start(SSH2_MSG_IGNORE); 128 packet_put_cstring("markus"); 129 packet_send(); 130 packet_write_wait(); 131 #endif 132 debug("done: ssh_kex2."); 133 } 134 135 /* 136 * Authenticate user 137 */ 138 139 typedef struct Authctxt Authctxt; 140 typedef struct Authmethod Authmethod; 141 142 typedef int sign_cb_fn( 143 Authctxt *authctxt, Key *key, 144 u_char **sigp, u_int *lenp, u_char *data, u_int datalen); 145 146 struct Authctxt { 147 const char *server_user; 148 const char *local_user; 149 const char *host; 150 const char *service; 151 Authmethod *method; 152 int success; 153 char *authlist; 154 /* pubkey */ 155 Key *last_key; 156 sign_cb_fn *last_key_sign; 157 int last_key_hint; 158 AuthenticationConnection *agent; 159 /* hostbased */ 160 Sensitive *sensitive; 161 /* kbd-interactive */ 162 int info_req_seen; 163 }; 164 struct Authmethod { 165 char *name; /* string to compare against server's list */ 166 int (*userauth)(Authctxt *authctxt); 167 int *enabled; /* flag in option struct that enables method */ 168 int *batch_flag; /* flag in option struct that disables method */ 169 }; 170 171 void input_userauth_success(int, u_int32_t, void *); 172 void input_userauth_failure(int, u_int32_t, void *); 173 void input_userauth_banner(int, u_int32_t, void *); 174 void input_userauth_error(int, u_int32_t, void *); 175 void input_userauth_info_req(int, u_int32_t, void *); 176 void input_userauth_pk_ok(int, u_int32_t, void *); 177 void input_userauth_passwd_changereq(int, u_int32_t, void *); 178 179 int userauth_none(Authctxt *); 180 int userauth_pubkey(Authctxt *); 181 int userauth_passwd(Authctxt *); 182 int userauth_kbdint(Authctxt *); 183 int userauth_hostbased(Authctxt *); 184 185 void userauth(Authctxt *, char *); 186 187 static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *); 188 static void clear_auth_state(Authctxt *); 189 190 static Authmethod *authmethod_get(char *authlist); 191 static Authmethod *authmethod_lookup(const char *name); 192 static char *authmethods_get(void); 193 194 Authmethod authmethods[] = { 195 {"hostbased", 196 userauth_hostbased, 197 &options.hostbased_authentication, 198 NULL}, 199 {"publickey", 200 userauth_pubkey, 201 &options.pubkey_authentication, 202 NULL}, 203 {"keyboard-interactive", 204 userauth_kbdint, 205 &options.kbd_interactive_authentication, 206 &options.batch_mode}, 207 {"password", 208 userauth_passwd, 209 &options.password_authentication, 210 &options.batch_mode}, 211 {"none", 212 userauth_none, 213 NULL, 214 NULL}, 215 {NULL, NULL, NULL, NULL} 216 }; 217 218 void 219 ssh_userauth2(const char *local_user, const char *server_user, char *host, 220 Sensitive *sensitive) 221 { 222 Authctxt authctxt; 223 int type; 224 225 if (options.challenge_response_authentication) 226 options.kbd_interactive_authentication = 1; 227 228 debug("send SSH2_MSG_SERVICE_REQUEST"); 229 packet_start(SSH2_MSG_SERVICE_REQUEST); 230 packet_put_cstring("ssh-userauth"); 231 packet_send(); 232 packet_write_wait(); 233 type = packet_read(); 234 if (type != SSH2_MSG_SERVICE_ACCEPT) { 235 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); 236 } 237 if (packet_remaining() > 0) { 238 char *reply = packet_get_string(NULL); 239 debug("service_accept: %s", reply); 240 xfree(reply); 241 } else { 242 debug("buggy server: service_accept w/o service"); 243 } 244 packet_check_eom(); 245 debug("got SSH2_MSG_SERVICE_ACCEPT"); 246 247 if (options.preferred_authentications == NULL) 248 options.preferred_authentications = authmethods_get(); 249 250 /* setup authentication context */ 251 memset(&authctxt, 0, sizeof(authctxt)); 252 authctxt.agent = ssh_get_authentication_connection(); 253 authctxt.server_user = server_user; 254 authctxt.local_user = local_user; 255 authctxt.host = host; 256 authctxt.service = "ssh-connection"; /* service name */ 257 authctxt.success = 0; 258 authctxt.method = authmethod_lookup("none"); 259 authctxt.authlist = NULL; 260 authctxt.sensitive = sensitive; 261 authctxt.info_req_seen = 0; 262 if (authctxt.method == NULL) 263 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 264 265 /* initial userauth request */ 266 userauth_none(&authctxt); 267 268 dispatch_init(&input_userauth_error); 269 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 270 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 271 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 272 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 273 274 if (authctxt.agent != NULL) 275 ssh_close_authentication_connection(authctxt.agent); 276 277 debug("ssh-userauth2 successful: method %s", authctxt.method->name); 278 } 279 void 280 userauth(Authctxt *authctxt, char *authlist) 281 { 282 if (authlist == NULL) { 283 authlist = authctxt->authlist; 284 } else { 285 if (authctxt->authlist) 286 xfree(authctxt->authlist); 287 authctxt->authlist = authlist; 288 } 289 for (;;) { 290 Authmethod *method = authmethod_get(authlist); 291 if (method == NULL) 292 fatal("Permission denied (%s).", authlist); 293 authctxt->method = method; 294 if (method->userauth(authctxt) != 0) { 295 debug2("we sent a %s packet, wait for reply", method->name); 296 break; 297 } else { 298 debug2("we did not send a packet, disable method"); 299 method->enabled = NULL; 300 } 301 } 302 } 303 void 304 input_userauth_error(int type, u_int32_t seq, void *ctxt) 305 { 306 fatal("input_userauth_error: bad message during authentication: " 307 "type %d", type); 308 } 309 void 310 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 311 { 312 char *msg, *lang; 313 debug3("input_userauth_banner"); 314 msg = packet_get_string(NULL); 315 lang = packet_get_string(NULL); 316 fprintf(stderr, "%s", msg); 317 xfree(msg); 318 xfree(lang); 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 void 332 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 333 { 334 Authctxt *authctxt = ctxt; 335 char *authlist = NULL; 336 int partial; 337 338 if (authctxt == NULL) 339 fatal("input_userauth_failure: no authentication context"); 340 341 authlist = packet_get_string(NULL); 342 partial = packet_get_char(); 343 packet_check_eom(); 344 345 if (partial != 0) 346 log("Authenticated with partial success."); 347 debug("authentications that can continue: %s", authlist); 348 349 clear_auth_state(authctxt); 350 userauth(authctxt, authlist); 351 } 352 void 353 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 354 { 355 Authctxt *authctxt = ctxt; 356 Key *key = NULL; 357 Buffer b; 358 int pktype, sent = 0; 359 u_int alen, blen; 360 char *pkalg, *fp; 361 u_char *pkblob; 362 363 if (authctxt == NULL) 364 fatal("input_userauth_pk_ok: no authentication context"); 365 if (datafellows & SSH_BUG_PKOK) { 366 /* this is similar to SSH_BUG_PKAUTH */ 367 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 368 pkblob = packet_get_string(&blen); 369 buffer_init(&b); 370 buffer_append(&b, pkblob, blen); 371 pkalg = buffer_get_string(&b, &alen); 372 buffer_free(&b); 373 } else { 374 pkalg = packet_get_string(&alen); 375 pkblob = packet_get_string(&blen); 376 } 377 packet_check_eom(); 378 379 debug("input_userauth_pk_ok: pkalg %s blen %d lastkey %p hint %d", 380 pkalg, blen, authctxt->last_key, authctxt->last_key_hint); 381 382 do { 383 if (authctxt->last_key == NULL || 384 authctxt->last_key_sign == NULL) { 385 debug("no last key or no sign cb"); 386 break; 387 } 388 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 389 debug("unknown pkalg %s", pkalg); 390 break; 391 } 392 if ((key = key_from_blob(pkblob, blen)) == NULL) { 393 debug("no key from blob. pkalg %s", pkalg); 394 break; 395 } 396 if (key->type != pktype) { 397 error("input_userauth_pk_ok: type mismatch " 398 "for decoded key (received %d, expected %d)", 399 key->type, pktype); 400 break; 401 } 402 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 403 debug2("input_userauth_pk_ok: fp %s", fp); 404 xfree(fp); 405 if (!key_equal(key, authctxt->last_key)) { 406 debug("key != last_key"); 407 break; 408 } 409 sent = sign_and_send_pubkey(authctxt, key, 410 authctxt->last_key_sign); 411 } while (0); 412 413 if (key != NULL) 414 key_free(key); 415 xfree(pkalg); 416 xfree(pkblob); 417 418 /* unregister */ 419 clear_auth_state(authctxt); 420 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); 421 422 /* try another method if we did not send a packet*/ 423 if (sent == 0) 424 userauth(authctxt, NULL); 425 426 } 427 428 int 429 userauth_none(Authctxt *authctxt) 430 { 431 /* initial userauth request */ 432 packet_start(SSH2_MSG_USERAUTH_REQUEST); 433 packet_put_cstring(authctxt->server_user); 434 packet_put_cstring(authctxt->service); 435 packet_put_cstring(authctxt->method->name); 436 packet_send(); 437 return 1; 438 } 439 440 int 441 userauth_passwd(Authctxt *authctxt) 442 { 443 static int attempt = 0; 444 char prompt[150]; 445 char *password; 446 447 if (attempt++ >= options.number_of_password_prompts) 448 return 0; 449 450 if (attempt != 1) 451 error("Permission denied, please try again."); 452 453 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 454 authctxt->server_user, authctxt->host); 455 password = read_passphrase(prompt, 0); 456 packet_start(SSH2_MSG_USERAUTH_REQUEST); 457 packet_put_cstring(authctxt->server_user); 458 packet_put_cstring(authctxt->service); 459 packet_put_cstring(authctxt->method->name); 460 packet_put_char(0); 461 packet_put_cstring(password); 462 memset(password, 0, strlen(password)); 463 xfree(password); 464 packet_add_padding(64); 465 packet_send(); 466 467 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 468 &input_userauth_passwd_changereq); 469 470 return 1; 471 } 472 /* 473 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 474 */ 475 void 476 input_userauth_passwd_changereq(int type, uint32_t seqnr, void *ctxt) 477 { 478 Authctxt *authctxt = ctxt; 479 char *info, *lang, *password = NULL, *retype = NULL; 480 char prompt[150]; 481 482 debug2("input_userauth_passwd_changereq"); 483 484 if (authctxt == NULL) 485 fatal("input_userauth_passwd_changereq: " 486 "no authentication context"); 487 488 info = packet_get_string(NULL); 489 lang = packet_get_string(NULL); 490 if (strlen(info) > 0) 491 log("%s", info); 492 xfree(info); 493 xfree(lang); 494 packet_start(SSH2_MSG_USERAUTH_REQUEST); 495 packet_put_cstring(authctxt->server_user); 496 packet_put_cstring(authctxt->service); 497 packet_put_cstring(authctxt->method->name); 498 packet_put_char(1); /* additional info */ 499 snprintf(prompt, sizeof(prompt), 500 "Enter %.30s@%.128s's old password: ", 501 authctxt->server_user, authctxt->host); 502 password = read_passphrase(prompt, 0); 503 packet_put_cstring(password); 504 memset(password, 0, strlen(password)); 505 xfree(password); 506 password = NULL; 507 while (password == NULL) { 508 snprintf(prompt, sizeof(prompt), 509 "Enter %.30s@%.128s's new password: ", 510 authctxt->server_user, authctxt->host); 511 password = read_passphrase(prompt, RP_ALLOW_EOF); 512 if (password == NULL) { 513 /* bail out */ 514 return; 515 } 516 snprintf(prompt, sizeof(prompt), 517 "Retype %.30s@%.128s's new password: ", 518 authctxt->server_user, authctxt->host); 519 retype = read_passphrase(prompt, 0); 520 if (strcmp(password, retype) != 0) { 521 memset(password, 0, strlen(password)); 522 xfree(password); 523 log("Mismatch; try again, EOF to quit."); 524 password = NULL; 525 } 526 memset(retype, 0, strlen(retype)); 527 xfree(retype); 528 } 529 packet_put_cstring(password); 530 memset(password, 0, strlen(password)); 531 xfree(password); 532 packet_add_padding(64); 533 packet_send(); 534 535 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 536 &input_userauth_passwd_changereq); 537 } 538 539 static void 540 clear_auth_state(Authctxt *authctxt) 541 { 542 /* XXX clear authentication state */ 543 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL); 544 545 if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { 546 debug3("clear_auth_state: key_free %p", authctxt->last_key); 547 key_free(authctxt->last_key); 548 } 549 authctxt->last_key = NULL; 550 authctxt->last_key_hint = -2; 551 authctxt->last_key_sign = NULL; 552 } 553 554 static int 555 sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) 556 { 557 Buffer b; 558 u_char *blob, *signature; 559 u_int bloblen, slen; 560 int skip = 0; 561 int ret = -1; 562 int have_sig = 1; 563 564 debug3("sign_and_send_pubkey"); 565 566 if (key_to_blob(k, &blob, &bloblen) == 0) { 567 /* we cannot handle this key */ 568 debug3("sign_and_send_pubkey: cannot handle key"); 569 return 0; 570 } 571 /* data to be signed */ 572 buffer_init(&b); 573 if (datafellows & SSH_OLD_SESSIONID) { 574 buffer_append(&b, session_id2, session_id2_len); 575 skip = session_id2_len; 576 } else { 577 buffer_put_string(&b, session_id2, session_id2_len); 578 skip = buffer_len(&b); 579 } 580 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 581 buffer_put_cstring(&b, authctxt->server_user); 582 buffer_put_cstring(&b, 583 datafellows & SSH_BUG_PKSERVICE ? 584 "ssh-userauth" : 585 authctxt->service); 586 if (datafellows & SSH_BUG_PKAUTH) { 587 buffer_put_char(&b, have_sig); 588 } else { 589 buffer_put_cstring(&b, authctxt->method->name); 590 buffer_put_char(&b, have_sig); 591 buffer_put_cstring(&b, key_ssh_name(k)); 592 } 593 buffer_put_string(&b, blob, bloblen); 594 595 /* generate signature */ 596 ret = (*sign_callback)(authctxt, k, &signature, &slen, 597 buffer_ptr(&b), buffer_len(&b)); 598 if (ret == -1) { 599 xfree(blob); 600 buffer_free(&b); 601 return 0; 602 } 603 #ifdef DEBUG_PK 604 buffer_dump(&b); 605 #endif 606 if (datafellows & SSH_BUG_PKSERVICE) { 607 buffer_clear(&b); 608 buffer_append(&b, session_id2, session_id2_len); 609 skip = session_id2_len; 610 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 611 buffer_put_cstring(&b, authctxt->server_user); 612 buffer_put_cstring(&b, authctxt->service); 613 buffer_put_cstring(&b, authctxt->method->name); 614 buffer_put_char(&b, have_sig); 615 if (!(datafellows & SSH_BUG_PKAUTH)) 616 buffer_put_cstring(&b, key_ssh_name(k)); 617 buffer_put_string(&b, blob, bloblen); 618 } 619 xfree(blob); 620 621 /* append signature */ 622 buffer_put_string(&b, signature, slen); 623 xfree(signature); 624 625 /* skip session id and packet type */ 626 if (buffer_len(&b) < skip + 1) 627 fatal("userauth_pubkey: internal error"); 628 buffer_consume(&b, skip + 1); 629 630 /* put remaining data from buffer into packet */ 631 packet_start(SSH2_MSG_USERAUTH_REQUEST); 632 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 633 buffer_free(&b); 634 packet_send(); 635 636 return 1; 637 } 638 639 static int 640 send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, 641 int hint) 642 { 643 u_char *blob; 644 u_int bloblen, have_sig = 0; 645 646 debug3("send_pubkey_test"); 647 648 if (key_to_blob(k, &blob, &bloblen) == 0) { 649 /* we cannot handle this key */ 650 debug3("send_pubkey_test: cannot handle key"); 651 return 0; 652 } 653 /* register callback for USERAUTH_PK_OK message */ 654 authctxt->last_key_sign = sign_callback; 655 authctxt->last_key_hint = hint; 656 authctxt->last_key = k; 657 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 658 659 packet_start(SSH2_MSG_USERAUTH_REQUEST); 660 packet_put_cstring(authctxt->server_user); 661 packet_put_cstring(authctxt->service); 662 packet_put_cstring(authctxt->method->name); 663 packet_put_char(have_sig); 664 if (!(datafellows & SSH_BUG_PKAUTH)) 665 packet_put_cstring(key_ssh_name(k)); 666 packet_put_string(blob, bloblen); 667 xfree(blob); 668 packet_send(); 669 return 1; 670 } 671 672 static Key * 673 load_identity_file(char *filename) 674 { 675 Key *private; 676 char prompt[300], *passphrase; 677 int quit, i; 678 struct stat st; 679 680 if (stat(filename, &st) < 0) { 681 debug3("no such identity: %s", filename); 682 return NULL; 683 } 684 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 685 if (private == NULL) { 686 if (options.batch_mode) 687 return NULL; 688 snprintf(prompt, sizeof prompt, 689 "Enter passphrase for key '%.100s': ", filename); 690 for (i = 0; i < options.number_of_password_prompts; i++) { 691 passphrase = read_passphrase(prompt, 0); 692 if (strcmp(passphrase, "") != 0) { 693 private = key_load_private_type(KEY_UNSPEC, filename, 694 passphrase, NULL); 695 quit = 0; 696 } else { 697 debug2("no passphrase given, try next key"); 698 quit = 1; 699 } 700 memset(passphrase, 0, strlen(passphrase)); 701 xfree(passphrase); 702 if (private != NULL || quit) 703 break; 704 debug2("bad passphrase given, try again..."); 705 } 706 } 707 return private; 708 } 709 710 static int 711 identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 712 u_char *data, u_int datalen) 713 { 714 Key *private; 715 int idx, ret; 716 717 idx = authctxt->last_key_hint; 718 if (idx < 0) 719 return -1; 720 721 /* private key is stored in external hardware */ 722 if (options.identity_keys[idx]->flags & KEY_FLAG_EXT) 723 return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen); 724 725 private = load_identity_file(options.identity_files[idx]); 726 if (private == NULL) 727 return -1; 728 ret = key_sign(private, sigp, lenp, data, datalen); 729 key_free(private); 730 return ret; 731 } 732 733 static int 734 agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 735 u_char *data, u_int datalen) 736 { 737 return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); 738 } 739 740 static int 741 key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 742 u_char *data, u_int datalen) 743 { 744 return key_sign(key, sigp, lenp, data, datalen); 745 } 746 747 static int 748 userauth_pubkey_agent(Authctxt *authctxt) 749 { 750 static int called = 0; 751 int ret = 0; 752 char *comment; 753 Key *k; 754 755 if (called == 0) { 756 if (ssh_get_num_identities(authctxt->agent, 2) == 0) 757 debug2("userauth_pubkey_agent: no keys at all"); 758 called = 1; 759 } 760 k = ssh_get_next_identity(authctxt->agent, &comment, 2); 761 if (k == NULL) { 762 debug2("userauth_pubkey_agent: no more keys"); 763 } else { 764 debug("userauth_pubkey_agent: testing agent key %s", comment); 765 xfree(comment); 766 ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); 767 if (ret == 0) 768 key_free(k); 769 } 770 if (ret == 0) 771 debug2("userauth_pubkey_agent: no message sent"); 772 return ret; 773 } 774 775 int 776 userauth_pubkey(Authctxt *authctxt) 777 { 778 static int idx = 0; 779 int sent = 0; 780 Key *key; 781 char *filename; 782 783 if (authctxt->agent != NULL) { 784 do { 785 sent = userauth_pubkey_agent(authctxt); 786 } while (!sent && authctxt->agent->howmany > 0); 787 } 788 while (!sent && idx < options.num_identity_files) { 789 key = options.identity_keys[idx]; 790 filename = options.identity_files[idx]; 791 if (key == NULL) { 792 debug("try privkey: %s", filename); 793 key = load_identity_file(filename); 794 if (key != NULL) { 795 sent = sign_and_send_pubkey(authctxt, key, 796 key_sign_cb); 797 key_free(key); 798 } 799 } else if (key->type != KEY_RSA1) { 800 debug("try pubkey: %s", filename); 801 sent = send_pubkey_test(authctxt, key, 802 identity_sign_cb, idx); 803 } 804 idx++; 805 } 806 return sent; 807 } 808 809 /* 810 * Send userauth request message specifying keyboard-interactive method. 811 */ 812 int 813 userauth_kbdint(Authctxt *authctxt) 814 { 815 static int attempt = 0; 816 817 if (attempt++ >= options.number_of_password_prompts) 818 return 0; 819 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 820 if (attempt > 1 && !authctxt->info_req_seen) { 821 debug3("userauth_kbdint: disable: no info_req_seen"); 822 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 823 return 0; 824 } 825 826 debug2("userauth_kbdint"); 827 packet_start(SSH2_MSG_USERAUTH_REQUEST); 828 packet_put_cstring(authctxt->server_user); 829 packet_put_cstring(authctxt->service); 830 packet_put_cstring(authctxt->method->name); 831 packet_put_cstring(""); /* lang */ 832 packet_put_cstring(options.kbd_interactive_devices ? 833 options.kbd_interactive_devices : ""); 834 packet_send(); 835 836 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 837 return 1; 838 } 839 840 /* 841 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 842 */ 843 void 844 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 845 { 846 Authctxt *authctxt = ctxt; 847 char *name, *inst, *lang, *prompt, *response; 848 u_int num_prompts, i; 849 int echo = 0; 850 851 debug2("input_userauth_info_req"); 852 853 if (authctxt == NULL) 854 fatal("input_userauth_info_req: no authentication context"); 855 856 authctxt->info_req_seen = 1; 857 858 name = packet_get_string(NULL); 859 inst = packet_get_string(NULL); 860 lang = packet_get_string(NULL); 861 if (strlen(name) > 0) 862 log("%s", name); 863 if (strlen(inst) > 0) 864 log("%s", inst); 865 xfree(name); 866 xfree(inst); 867 xfree(lang); 868 869 num_prompts = packet_get_int(); 870 /* 871 * Begin to build info response packet based on prompts requested. 872 * We commit to providing the correct number of responses, so if 873 * further on we run into a problem that prevents this, we have to 874 * be sure and clean this up and send a correct error response. 875 */ 876 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 877 packet_put_int(num_prompts); 878 879 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 880 for (i = 0; i < num_prompts; i++) { 881 prompt = packet_get_string(NULL); 882 echo = packet_get_char(); 883 884 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 885 886 packet_put_cstring(response); 887 memset(response, 0, strlen(response)); 888 xfree(response); 889 xfree(prompt); 890 } 891 packet_check_eom(); /* done with parsing incoming message. */ 892 893 packet_add_padding(64); 894 packet_send(); 895 } 896 897 static int 898 ssh_keysign( 899 Key *key, 900 u_char **sigp, u_int *lenp, 901 u_char *data, u_int datalen) 902 { 903 Buffer b; 904 struct stat st; 905 pid_t pid; 906 int to[2], from[2], status, version = 2; 907 908 debug("ssh_keysign called"); 909 910 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 911 error("ssh_keysign: no installed: %s", strerror(errno)); 912 return -1; 913 } 914 if (fflush(stdout) != 0) 915 error("ssh_keysign: fflush: %s", strerror(errno)); 916 if (pipe(to) < 0) { 917 error("ssh_keysign: pipe: %s", strerror(errno)); 918 return -1; 919 } 920 if (pipe(from) < 0) { 921 error("ssh_keysign: pipe: %s", strerror(errno)); 922 return -1; 923 } 924 if ((pid = fork()) < 0) { 925 error("ssh_keysign: fork: %s", strerror(errno)); 926 return -1; 927 } 928 if (pid == 0) { 929 seteuid(getuid()); 930 setuid(getuid()); 931 close(from[0]); 932 if (dup2(from[1], STDOUT_FILENO) < 0) 933 fatal("ssh_keysign: dup2: %s", strerror(errno)); 934 close(to[1]); 935 if (dup2(to[0], STDIN_FILENO) < 0) 936 fatal("ssh_keysign: dup2: %s", strerror(errno)); 937 close(from[1]); 938 close(to[0]); 939 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 940 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 941 strerror(errno)); 942 } 943 close(from[1]); 944 close(to[0]); 945 946 buffer_init(&b); 947 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 948 buffer_put_string(&b, data, datalen); 949 msg_send(to[1], version, &b); 950 951 if (msg_recv(from[0], &b) < 0) { 952 error("ssh_keysign: no reply"); 953 buffer_clear(&b); 954 return -1; 955 } 956 close(from[0]); 957 close(to[1]); 958 959 while (waitpid(pid, &status, 0) < 0) 960 if (errno != EINTR) 961 break; 962 963 if (buffer_get_char(&b) != version) { 964 error("ssh_keysign: bad version"); 965 buffer_clear(&b); 966 return -1; 967 } 968 *sigp = buffer_get_string(&b, lenp); 969 buffer_clear(&b); 970 971 return 0; 972 } 973 974 int 975 userauth_hostbased(Authctxt *authctxt) 976 { 977 Key *private = NULL; 978 Sensitive *sensitive = authctxt->sensitive; 979 Buffer b; 980 u_char *signature, *blob; 981 char *chost, *pkalg, *p; 982 const char *service; 983 u_int blen, slen; 984 int ok, i, len, found = 0; 985 986 /* check for a useful key */ 987 for (i = 0; i < sensitive->nkeys; i++) { 988 private = sensitive->keys[i]; 989 if (private && private->type != KEY_RSA1) { 990 found = 1; 991 /* we take and free the key */ 992 sensitive->keys[i] = NULL; 993 break; 994 } 995 } 996 if (!found) { 997 debug("userauth_hostbased: no more client hostkeys"); 998 return 0; 999 } 1000 if (key_to_blob(private, &blob, &blen) == 0) { 1001 key_free(private); 1002 return 0; 1003 } 1004 /* figure out a name for the client host */ 1005 p = get_local_name(packet_get_connection_in()); 1006 if (p == NULL) { 1007 error("userauth_hostbased: cannot get local ipaddr/name"); 1008 key_free(private); 1009 return 0; 1010 } 1011 len = strlen(p) + 2; 1012 chost = xmalloc(len); 1013 strlcpy(chost, p, len); 1014 strlcat(chost, ".", len); 1015 debug2("userauth_hostbased: chost %s", chost); 1016 1017 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1018 authctxt->service; 1019 pkalg = xstrdup(key_ssh_name(private)); 1020 buffer_init(&b); 1021 /* construct data */ 1022 buffer_put_string(&b, session_id2, session_id2_len); 1023 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1024 buffer_put_cstring(&b, authctxt->server_user); 1025 buffer_put_cstring(&b, service); 1026 buffer_put_cstring(&b, authctxt->method->name); 1027 buffer_put_cstring(&b, pkalg); 1028 buffer_put_string(&b, blob, blen); 1029 buffer_put_cstring(&b, chost); 1030 buffer_put_cstring(&b, authctxt->local_user); 1031 #ifdef DEBUG_PK 1032 buffer_dump(&b); 1033 #endif 1034 if (sensitive->external_keysign) 1035 ok = ssh_keysign(private, &signature, &slen, 1036 buffer_ptr(&b), buffer_len(&b)); 1037 else 1038 ok = key_sign(private, &signature, &slen, 1039 buffer_ptr(&b), buffer_len(&b)); 1040 key_free(private); 1041 buffer_free(&b); 1042 if (ok != 0) { 1043 error("key_sign failed"); 1044 xfree(chost); 1045 xfree(pkalg); 1046 return 0; 1047 } 1048 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1049 packet_put_cstring(authctxt->server_user); 1050 packet_put_cstring(authctxt->service); 1051 packet_put_cstring(authctxt->method->name); 1052 packet_put_cstring(pkalg); 1053 packet_put_string(blob, blen); 1054 packet_put_cstring(chost); 1055 packet_put_cstring(authctxt->local_user); 1056 packet_put_string(signature, slen); 1057 memset(signature, 's', slen); 1058 xfree(signature); 1059 xfree(chost); 1060 xfree(pkalg); 1061 1062 packet_send(); 1063 return 1; 1064 } 1065 1066 /* find auth method */ 1067 1068 /* 1069 * given auth method name, if configurable options permit this method fill 1070 * in auth_ident field and return true, otherwise return false. 1071 */ 1072 static int 1073 authmethod_is_enabled(Authmethod *method) 1074 { 1075 if (method == NULL) 1076 return 0; 1077 /* return false if options indicate this method is disabled */ 1078 if (method->enabled == NULL || *method->enabled == 0) 1079 return 0; 1080 /* return false if batch mode is enabled but method needs interactive mode */ 1081 if (method->batch_flag != NULL && *method->batch_flag != 0) 1082 return 0; 1083 return 1; 1084 } 1085 1086 static Authmethod * 1087 authmethod_lookup(const char *name) 1088 { 1089 Authmethod *method = NULL; 1090 if (name != NULL) 1091 for (method = authmethods; method->name != NULL; method++) 1092 if (strcmp(name, method->name) == 0) 1093 return method; 1094 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1095 return NULL; 1096 } 1097 1098 /* XXX internal state */ 1099 static Authmethod *current = NULL; 1100 static char *supported = NULL; 1101 static char *preferred = NULL; 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