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 1.114 2003/04/01 10:22:21 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->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 114 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 115 kex->client_version_string=client_version_string; 116 kex->server_version_string=server_version_string; 117 kex->verify_host_key=&verify_host_key_callback; 118 119 xxx_kex = kex; 120 121 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 122 123 session_id2 = kex->session_id; 124 session_id2_len = kex->session_id_len; 125 126 #ifdef DEBUG_KEXDH 127 /* send 1st encrypted/maced/compressed message */ 128 packet_start(SSH2_MSG_IGNORE); 129 packet_put_cstring("markus"); 130 packet_send(); 131 packet_write_wait(); 132 #endif 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 packet_start(SSH2_MSG_SERVICE_REQUEST); 229 packet_put_cstring("ssh-userauth"); 230 packet_send(); 231 debug("SSH2_MSG_SERVICE_REQUEST sent"); 232 packet_write_wait(); 233 type = packet_read(); 234 if (type != SSH2_MSG_SERVICE_ACCEPT) 235 fatal("Server denied authentication request: %d", type); 236 if (packet_remaining() > 0) { 237 char *reply = packet_get_string(NULL); 238 debug2("service_accept: %s", reply); 239 xfree(reply); 240 } else { 241 debug2("buggy server: service_accept w/o service"); 242 } 243 packet_check_eom(); 244 debug("SSH2_MSG_SERVICE_ACCEPT received"); 245 246 if (options.preferred_authentications == NULL) 247 options.preferred_authentications = authmethods_get(); 248 249 /* setup authentication context */ 250 memset(&authctxt, 0, sizeof(authctxt)); 251 authctxt.agent = ssh_get_authentication_connection(); 252 authctxt.server_user = server_user; 253 authctxt.local_user = local_user; 254 authctxt.host = host; 255 authctxt.service = "ssh-connection"; /* service name */ 256 authctxt.success = 0; 257 authctxt.method = authmethod_lookup("none"); 258 authctxt.authlist = NULL; 259 authctxt.sensitive = sensitive; 260 authctxt.info_req_seen = 0; 261 if (authctxt.method == NULL) 262 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 263 264 /* initial userauth request */ 265 userauth_none(&authctxt); 266 267 dispatch_init(&input_userauth_error); 268 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 269 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 270 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 271 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 272 273 if (authctxt.agent != NULL) 274 ssh_close_authentication_connection(authctxt.agent); 275 276 debug("Authentication succeeded (%s).", authctxt.method->name); 277 } 278 void 279 userauth(Authctxt *authctxt, char *authlist) 280 { 281 if (authlist == NULL) { 282 authlist = authctxt->authlist; 283 } else { 284 if (authctxt->authlist) 285 xfree(authctxt->authlist); 286 authctxt->authlist = authlist; 287 } 288 for (;;) { 289 Authmethod *method = authmethod_get(authlist); 290 if (method == NULL) 291 fatal("Permission denied (%s).", authlist); 292 authctxt->method = method; 293 if (method->userauth(authctxt) != 0) { 294 debug2("we sent a %s packet, wait for reply", method->name); 295 break; 296 } else { 297 debug2("we did not send a packet, disable method"); 298 method->enabled = NULL; 299 } 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 } 309 310 void 311 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 312 { 313 char *msg, *lang; 314 debug3("input_userauth_banner"); 315 msg = packet_get_string(NULL); 316 lang = packet_get_string(NULL); 317 fprintf(stderr, "%s", msg); 318 xfree(msg); 319 xfree(lang); 320 } 321 322 void 323 input_userauth_success(int type, u_int32_t seq, void *ctxt) 324 { 325 Authctxt *authctxt = ctxt; 326 if (authctxt == NULL) 327 fatal("input_userauth_success: no authentication context"); 328 if (authctxt->authlist) 329 xfree(authctxt->authlist); 330 clear_auth_state(authctxt); 331 authctxt->success = 1; /* break out */ 332 } 333 334 void 335 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 336 { 337 Authctxt *authctxt = ctxt; 338 char *authlist = NULL; 339 int partial; 340 341 if (authctxt == NULL) 342 fatal("input_userauth_failure: no authentication context"); 343 344 authlist = packet_get_string(NULL); 345 partial = packet_get_char(); 346 packet_check_eom(); 347 348 if (partial != 0) 349 log("Authenticated with partial success."); 350 debug("Authentications that can continue: %s", authlist); 351 352 clear_auth_state(authctxt); 353 userauth(authctxt, authlist); 354 } 355 void 356 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 357 { 358 Authctxt *authctxt = ctxt; 359 Key *key = NULL; 360 Buffer b; 361 int pktype, sent = 0; 362 u_int alen, blen; 363 char *pkalg, *fp; 364 u_char *pkblob; 365 366 if (authctxt == NULL) 367 fatal("input_userauth_pk_ok: no authentication context"); 368 if (datafellows & SSH_BUG_PKOK) { 369 /* this is similar to SSH_BUG_PKAUTH */ 370 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 371 pkblob = packet_get_string(&blen); 372 buffer_init(&b); 373 buffer_append(&b, pkblob, blen); 374 pkalg = buffer_get_string(&b, &alen); 375 buffer_free(&b); 376 } else { 377 pkalg = packet_get_string(&alen); 378 pkblob = packet_get_string(&blen); 379 } 380 packet_check_eom(); 381 382 debug("Server accepts key: pkalg %s blen %u lastkey %p hint %d", 383 pkalg, blen, authctxt->last_key, authctxt->last_key_hint); 384 385 do { 386 if (authctxt->last_key == NULL || 387 authctxt->last_key_sign == NULL) { 388 debug("no last key or no sign cb"); 389 break; 390 } 391 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 392 debug("unknown pkalg %s", pkalg); 393 break; 394 } 395 if ((key = key_from_blob(pkblob, blen)) == NULL) { 396 debug("no key from blob. pkalg %s", pkalg); 397 break; 398 } 399 if (key->type != pktype) { 400 error("input_userauth_pk_ok: type mismatch " 401 "for decoded key (received %d, expected %d)", 402 key->type, pktype); 403 break; 404 } 405 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 406 debug2("input_userauth_pk_ok: fp %s", fp); 407 xfree(fp); 408 if (!key_equal(key, authctxt->last_key)) { 409 debug("key != last_key"); 410 break; 411 } 412 sent = sign_and_send_pubkey(authctxt, key, 413 authctxt->last_key_sign); 414 } while (0); 415 416 if (key != NULL) 417 key_free(key); 418 xfree(pkalg); 419 xfree(pkblob); 420 421 /* unregister */ 422 clear_auth_state(authctxt); 423 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); 424 425 /* try another method if we did not send a packet */ 426 if (sent == 0) 427 userauth(authctxt, NULL); 428 429 } 430 431 int 432 userauth_none(Authctxt *authctxt) 433 { 434 /* initial userauth request */ 435 packet_start(SSH2_MSG_USERAUTH_REQUEST); 436 packet_put_cstring(authctxt->server_user); 437 packet_put_cstring(authctxt->service); 438 packet_put_cstring(authctxt->method->name); 439 packet_send(); 440 return 1; 441 } 442 443 int 444 userauth_passwd(Authctxt *authctxt) 445 { 446 static int attempt = 0; 447 char prompt[150]; 448 char *password; 449 450 if (attempt++ >= options.number_of_password_prompts) 451 return 0; 452 453 if (attempt != 1) 454 error("Permission denied, please try again."); 455 456 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 457 authctxt->server_user, authctxt->host); 458 password = read_passphrase(prompt, 0); 459 packet_start(SSH2_MSG_USERAUTH_REQUEST); 460 packet_put_cstring(authctxt->server_user); 461 packet_put_cstring(authctxt->service); 462 packet_put_cstring(authctxt->method->name); 463 packet_put_char(0); 464 packet_put_cstring(password); 465 memset(password, 0, strlen(password)); 466 xfree(password); 467 packet_add_padding(64); 468 packet_send(); 469 470 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 471 &input_userauth_passwd_changereq); 472 473 return 1; 474 } 475 /* 476 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 477 */ 478 void 479 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 480 { 481 Authctxt *authctxt = ctxt; 482 char *info, *lang, *password = NULL, *retype = NULL; 483 char prompt[150]; 484 485 debug2("input_userauth_passwd_changereq"); 486 487 if (authctxt == NULL) 488 fatal("input_userauth_passwd_changereq: " 489 "no authentication context"); 490 491 info = packet_get_string(NULL); 492 lang = packet_get_string(NULL); 493 if (strlen(info) > 0) 494 log("%s", info); 495 xfree(info); 496 xfree(lang); 497 packet_start(SSH2_MSG_USERAUTH_REQUEST); 498 packet_put_cstring(authctxt->server_user); 499 packet_put_cstring(authctxt->service); 500 packet_put_cstring(authctxt->method->name); 501 packet_put_char(1); /* additional info */ 502 snprintf(prompt, sizeof(prompt), 503 "Enter %.30s@%.128s's old password: ", 504 authctxt->server_user, authctxt->host); 505 password = read_passphrase(prompt, 0); 506 packet_put_cstring(password); 507 memset(password, 0, strlen(password)); 508 xfree(password); 509 password = NULL; 510 while (password == NULL) { 511 snprintf(prompt, sizeof(prompt), 512 "Enter %.30s@%.128s's new password: ", 513 authctxt->server_user, authctxt->host); 514 password = read_passphrase(prompt, RP_ALLOW_EOF); 515 if (password == NULL) { 516 /* bail out */ 517 return; 518 } 519 snprintf(prompt, sizeof(prompt), 520 "Retype %.30s@%.128s's new password: ", 521 authctxt->server_user, authctxt->host); 522 retype = read_passphrase(prompt, 0); 523 if (strcmp(password, retype) != 0) { 524 memset(password, 0, strlen(password)); 525 xfree(password); 526 log("Mismatch; try again, EOF to quit."); 527 password = NULL; 528 } 529 memset(retype, 0, strlen(retype)); 530 xfree(retype); 531 } 532 packet_put_cstring(password); 533 memset(password, 0, strlen(password)); 534 xfree(password); 535 packet_add_padding(64); 536 packet_send(); 537 538 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 539 &input_userauth_passwd_changereq); 540 } 541 542 static void 543 clear_auth_state(Authctxt *authctxt) 544 { 545 /* XXX clear authentication state */ 546 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL); 547 548 if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { 549 debug3("clear_auth_state: key_free %p", authctxt->last_key); 550 key_free(authctxt->last_key); 551 } 552 authctxt->last_key = NULL; 553 authctxt->last_key_hint = -2; 554 authctxt->last_key_sign = NULL; 555 } 556 557 static int 558 sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) 559 { 560 Buffer b; 561 u_char *blob, *signature; 562 u_int bloblen, slen; 563 int skip = 0; 564 int ret = -1; 565 int have_sig = 1; 566 567 debug3("sign_and_send_pubkey"); 568 569 if (key_to_blob(k, &blob, &bloblen) == 0) { 570 /* we cannot handle this key */ 571 debug3("sign_and_send_pubkey: cannot handle key"); 572 return 0; 573 } 574 /* data to be signed */ 575 buffer_init(&b); 576 if (datafellows & SSH_OLD_SESSIONID) { 577 buffer_append(&b, session_id2, session_id2_len); 578 skip = session_id2_len; 579 } else { 580 buffer_put_string(&b, session_id2, session_id2_len); 581 skip = buffer_len(&b); 582 } 583 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 584 buffer_put_cstring(&b, authctxt->server_user); 585 buffer_put_cstring(&b, 586 datafellows & SSH_BUG_PKSERVICE ? 587 "ssh-userauth" : 588 authctxt->service); 589 if (datafellows & SSH_BUG_PKAUTH) { 590 buffer_put_char(&b, have_sig); 591 } else { 592 buffer_put_cstring(&b, authctxt->method->name); 593 buffer_put_char(&b, have_sig); 594 buffer_put_cstring(&b, key_ssh_name(k)); 595 } 596 buffer_put_string(&b, blob, bloblen); 597 598 /* generate signature */ 599 ret = (*sign_callback)(authctxt, k, &signature, &slen, 600 buffer_ptr(&b), buffer_len(&b)); 601 if (ret == -1) { 602 xfree(blob); 603 buffer_free(&b); 604 return 0; 605 } 606 #ifdef DEBUG_PK 607 buffer_dump(&b); 608 #endif 609 if (datafellows & SSH_BUG_PKSERVICE) { 610 buffer_clear(&b); 611 buffer_append(&b, session_id2, session_id2_len); 612 skip = session_id2_len; 613 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 614 buffer_put_cstring(&b, authctxt->server_user); 615 buffer_put_cstring(&b, authctxt->service); 616 buffer_put_cstring(&b, authctxt->method->name); 617 buffer_put_char(&b, have_sig); 618 if (!(datafellows & SSH_BUG_PKAUTH)) 619 buffer_put_cstring(&b, key_ssh_name(k)); 620 buffer_put_string(&b, blob, bloblen); 621 } 622 xfree(blob); 623 624 /* append signature */ 625 buffer_put_string(&b, signature, slen); 626 xfree(signature); 627 628 /* skip session id and packet type */ 629 if (buffer_len(&b) < skip + 1) 630 fatal("userauth_pubkey: internal error"); 631 buffer_consume(&b, skip + 1); 632 633 /* put remaining data from buffer into packet */ 634 packet_start(SSH2_MSG_USERAUTH_REQUEST); 635 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 636 buffer_free(&b); 637 packet_send(); 638 639 return 1; 640 } 641 642 static int 643 send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, 644 int hint) 645 { 646 u_char *blob; 647 u_int bloblen, have_sig = 0; 648 649 debug3("send_pubkey_test"); 650 651 if (key_to_blob(k, &blob, &bloblen) == 0) { 652 /* we cannot handle this key */ 653 debug3("send_pubkey_test: cannot handle key"); 654 return 0; 655 } 656 /* register callback for USERAUTH_PK_OK message */ 657 authctxt->last_key_sign = sign_callback; 658 authctxt->last_key_hint = hint; 659 authctxt->last_key = k; 660 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 661 662 packet_start(SSH2_MSG_USERAUTH_REQUEST); 663 packet_put_cstring(authctxt->server_user); 664 packet_put_cstring(authctxt->service); 665 packet_put_cstring(authctxt->method->name); 666 packet_put_char(have_sig); 667 if (!(datafellows & SSH_BUG_PKAUTH)) 668 packet_put_cstring(key_ssh_name(k)); 669 packet_put_string(blob, bloblen); 670 xfree(blob); 671 packet_send(); 672 return 1; 673 } 674 675 static Key * 676 load_identity_file(char *filename) 677 { 678 Key *private; 679 char prompt[300], *passphrase; 680 int quit, i; 681 struct stat st; 682 683 if (stat(filename, &st) < 0) { 684 debug3("no such identity: %s", filename); 685 return NULL; 686 } 687 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 688 if (private == NULL) { 689 if (options.batch_mode) 690 return NULL; 691 snprintf(prompt, sizeof prompt, 692 "Enter passphrase for key '%.100s': ", filename); 693 for (i = 0; i < options.number_of_password_prompts; i++) { 694 passphrase = read_passphrase(prompt, 0); 695 if (strcmp(passphrase, "") != 0) { 696 private = key_load_private_type(KEY_UNSPEC, filename, 697 passphrase, NULL); 698 quit = 0; 699 } else { 700 debug2("no passphrase given, try next key"); 701 quit = 1; 702 } 703 memset(passphrase, 0, strlen(passphrase)); 704 xfree(passphrase); 705 if (private != NULL || quit) 706 break; 707 debug2("bad passphrase given, try again..."); 708 } 709 } 710 return private; 711 } 712 713 static int 714 identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 715 u_char *data, u_int datalen) 716 { 717 Key *private; 718 int idx, ret; 719 720 idx = authctxt->last_key_hint; 721 if (idx < 0) 722 return -1; 723 724 /* private key is stored in external hardware */ 725 if (options.identity_keys[idx]->flags & KEY_FLAG_EXT) 726 return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen); 727 728 private = load_identity_file(options.identity_files[idx]); 729 if (private == NULL) 730 return -1; 731 ret = key_sign(private, sigp, lenp, data, datalen); 732 key_free(private); 733 return ret; 734 } 735 736 static int 737 agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 738 u_char *data, u_int datalen) 739 { 740 return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); 741 } 742 743 static int 744 key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 745 u_char *data, u_int datalen) 746 { 747 return key_sign(key, sigp, lenp, data, datalen); 748 } 749 750 static int 751 userauth_pubkey_agent(Authctxt *authctxt) 752 { 753 static int called = 0; 754 int ret = 0; 755 char *comment; 756 Key *k; 757 758 if (called == 0) { 759 if (ssh_get_num_identities(authctxt->agent, 2) == 0) 760 debug2("userauth_pubkey_agent: no keys at all"); 761 called = 1; 762 } 763 k = ssh_get_next_identity(authctxt->agent, &comment, 2); 764 if (k == NULL) { 765 debug2("userauth_pubkey_agent: no more keys"); 766 } else { 767 debug("Offering agent key: %s", comment); 768 xfree(comment); 769 ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); 770 if (ret == 0) 771 key_free(k); 772 } 773 if (ret == 0) 774 debug2("userauth_pubkey_agent: no message sent"); 775 return ret; 776 } 777 778 int 779 userauth_pubkey(Authctxt *authctxt) 780 { 781 static int idx = 0; 782 int sent = 0; 783 Key *key; 784 char *filename; 785 786 if (authctxt->agent != NULL) { 787 do { 788 sent = userauth_pubkey_agent(authctxt); 789 } while (!sent && authctxt->agent->howmany > 0); 790 } 791 while (!sent && idx < options.num_identity_files) { 792 key = options.identity_keys[idx]; 793 filename = options.identity_files[idx]; 794 if (key == NULL) { 795 debug("Trying private key: %s", filename); 796 key = load_identity_file(filename); 797 if (key != NULL) { 798 sent = sign_and_send_pubkey(authctxt, key, 799 key_sign_cb); 800 key_free(key); 801 } 802 } else if (key->type != KEY_RSA1) { 803 debug("Offering public key: %s", filename); 804 sent = send_pubkey_test(authctxt, key, 805 identity_sign_cb, idx); 806 } 807 idx++; 808 } 809 return sent; 810 } 811 812 /* 813 * Send userauth request message specifying keyboard-interactive method. 814 */ 815 int 816 userauth_kbdint(Authctxt *authctxt) 817 { 818 static int attempt = 0; 819 820 if (attempt++ >= options.number_of_password_prompts) 821 return 0; 822 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 823 if (attempt > 1 && !authctxt->info_req_seen) { 824 debug3("userauth_kbdint: disable: no info_req_seen"); 825 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 826 return 0; 827 } 828 829 debug2("userauth_kbdint"); 830 packet_start(SSH2_MSG_USERAUTH_REQUEST); 831 packet_put_cstring(authctxt->server_user); 832 packet_put_cstring(authctxt->service); 833 packet_put_cstring(authctxt->method->name); 834 packet_put_cstring(""); /* lang */ 835 packet_put_cstring(options.kbd_interactive_devices ? 836 options.kbd_interactive_devices : ""); 837 packet_send(); 838 839 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 840 return 1; 841 } 842 843 /* 844 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 845 */ 846 void 847 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 848 { 849 Authctxt *authctxt = ctxt; 850 char *name, *inst, *lang, *prompt, *response; 851 u_int num_prompts, i; 852 int echo = 0; 853 854 debug2("input_userauth_info_req"); 855 856 if (authctxt == NULL) 857 fatal("input_userauth_info_req: no authentication context"); 858 859 authctxt->info_req_seen = 1; 860 861 name = packet_get_string(NULL); 862 inst = packet_get_string(NULL); 863 lang = packet_get_string(NULL); 864 if (strlen(name) > 0) 865 log("%s", name); 866 if (strlen(inst) > 0) 867 log("%s", inst); 868 xfree(name); 869 xfree(inst); 870 xfree(lang); 871 872 num_prompts = packet_get_int(); 873 /* 874 * Begin to build info response packet based on prompts requested. 875 * We commit to providing the correct number of responses, so if 876 * further on we run into a problem that prevents this, we have to 877 * be sure and clean this up and send a correct error response. 878 */ 879 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 880 packet_put_int(num_prompts); 881 882 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 883 for (i = 0; i < num_prompts; i++) { 884 prompt = packet_get_string(NULL); 885 echo = packet_get_char(); 886 887 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 888 889 packet_put_cstring(response); 890 memset(response, 0, strlen(response)); 891 xfree(response); 892 xfree(prompt); 893 } 894 packet_check_eom(); /* done with parsing incoming message. */ 895 896 packet_add_padding(64); 897 packet_send(); 898 } 899 900 static int 901 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 902 u_char *data, u_int datalen) 903 { 904 Buffer b; 905 struct stat st; 906 pid_t pid; 907 int to[2], from[2], status, version = 2; 908 909 debug2("ssh_keysign called"); 910 911 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 912 error("ssh_keysign: no installed: %s", strerror(errno)); 913 return -1; 914 } 915 if (fflush(stdout) != 0) 916 error("ssh_keysign: fflush: %s", strerror(errno)); 917 if (pipe(to) < 0) { 918 error("ssh_keysign: pipe: %s", strerror(errno)); 919 return -1; 920 } 921 if (pipe(from) < 0) { 922 error("ssh_keysign: pipe: %s", strerror(errno)); 923 return -1; 924 } 925 if ((pid = fork()) < 0) { 926 error("ssh_keysign: fork: %s", strerror(errno)); 927 return -1; 928 } 929 if (pid == 0) { 930 seteuid(getuid()); 931 setuid(getuid()); 932 close(from[0]); 933 if (dup2(from[1], STDOUT_FILENO) < 0) 934 fatal("ssh_keysign: dup2: %s", strerror(errno)); 935 close(to[1]); 936 if (dup2(to[0], STDIN_FILENO) < 0) 937 fatal("ssh_keysign: dup2: %s", strerror(errno)); 938 close(from[1]); 939 close(to[0]); 940 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 941 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 942 strerror(errno)); 943 } 944 close(from[1]); 945 close(to[0]); 946 947 buffer_init(&b); 948 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 949 buffer_put_string(&b, data, datalen); 950 ssh_msg_send(to[1], version, &b); 951 952 if (ssh_msg_recv(from[0], &b) < 0) { 953 error("ssh_keysign: no reply"); 954 buffer_clear(&b); 955 return -1; 956 } 957 close(from[0]); 958 close(to[1]); 959 960 while (waitpid(pid, &status, 0) < 0) 961 if (errno != EINTR) 962 break; 963 964 if (buffer_get_char(&b) != version) { 965 error("ssh_keysign: bad version"); 966 buffer_clear(&b); 967 return -1; 968 } 969 *sigp = buffer_get_string(&b, lenp); 970 buffer_clear(&b); 971 972 return 0; 973 } 974 975 int 976 userauth_hostbased(Authctxt *authctxt) 977 { 978 Key *private = NULL; 979 Sensitive *sensitive = authctxt->sensitive; 980 Buffer b; 981 u_char *signature, *blob; 982 char *chost, *pkalg, *p; 983 const char *service; 984 u_int blen, slen; 985 int ok, i, len, found = 0; 986 987 /* check for a useful key */ 988 for (i = 0; i < sensitive->nkeys; i++) { 989 private = sensitive->keys[i]; 990 if (private && private->type != KEY_RSA1) { 991 found = 1; 992 /* we take and free the key */ 993 sensitive->keys[i] = NULL; 994 break; 995 } 996 } 997 if (!found) { 998 debug("No more client hostkeys for hostbased authentication."); 999 return 0; 1000 } 1001 if (key_to_blob(private, &blob, &blen) == 0) { 1002 key_free(private); 1003 return 0; 1004 } 1005 /* figure out a name for the client host */ 1006 p = get_local_name(packet_get_connection_in()); 1007 if (p == NULL) { 1008 error("userauth_hostbased: cannot get local ipaddr/name"); 1009 key_free(private); 1010 return 0; 1011 } 1012 len = strlen(p) + 2; 1013 chost = xmalloc(len); 1014 strlcpy(chost, p, len); 1015 strlcat(chost, ".", len); 1016 debug2("userauth_hostbased: chost %s", chost); 1017 xfree(p); 1018 1019 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1020 authctxt->service; 1021 pkalg = xstrdup(key_ssh_name(private)); 1022 buffer_init(&b); 1023 /* construct data */ 1024 buffer_put_string(&b, session_id2, session_id2_len); 1025 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1026 buffer_put_cstring(&b, authctxt->server_user); 1027 buffer_put_cstring(&b, service); 1028 buffer_put_cstring(&b, authctxt->method->name); 1029 buffer_put_cstring(&b, pkalg); 1030 buffer_put_string(&b, blob, blen); 1031 buffer_put_cstring(&b, chost); 1032 buffer_put_cstring(&b, authctxt->local_user); 1033 #ifdef DEBUG_PK 1034 buffer_dump(&b); 1035 #endif 1036 if (sensitive->external_keysign) 1037 ok = ssh_keysign(private, &signature, &slen, 1038 buffer_ptr(&b), buffer_len(&b)); 1039 else 1040 ok = key_sign(private, &signature, &slen, 1041 buffer_ptr(&b), buffer_len(&b)); 1042 key_free(private); 1043 buffer_free(&b); 1044 if (ok != 0) { 1045 error("key_sign failed"); 1046 xfree(chost); 1047 xfree(pkalg); 1048 return 0; 1049 } 1050 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1051 packet_put_cstring(authctxt->server_user); 1052 packet_put_cstring(authctxt->service); 1053 packet_put_cstring(authctxt->method->name); 1054 packet_put_cstring(pkalg); 1055 packet_put_string(blob, blen); 1056 packet_put_cstring(chost); 1057 packet_put_cstring(authctxt->local_user); 1058 packet_put_string(signature, slen); 1059 memset(signature, 's', slen); 1060 xfree(signature); 1061 xfree(chost); 1062 xfree(pkalg); 1063 1064 packet_send(); 1065 return 1; 1066 } 1067 1068 /* find auth method */ 1069 1070 /* 1071 * given auth method name, if configurable options permit this method fill 1072 * in auth_ident field and return true, otherwise return false. 1073 */ 1074 static int 1075 authmethod_is_enabled(Authmethod *method) 1076 { 1077 if (method == NULL) 1078 return 0; 1079 /* return false if options indicate this method is disabled */ 1080 if (method->enabled == NULL || *method->enabled == 0) 1081 return 0; 1082 /* return false if batch mode is enabled but method needs interactive mode */ 1083 if (method->batch_flag != NULL && *method->batch_flag != 0) 1084 return 0; 1085 return 1; 1086 } 1087 1088 static Authmethod * 1089 authmethod_lookup(const char *name) 1090 { 1091 Authmethod *method = NULL; 1092 if (name != NULL) 1093 for (method = authmethods; method->name != NULL; method++) 1094 if (strcmp(name, method->name) == 0) 1095 return method; 1096 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1097 return NULL; 1098 } 1099 1100 /* XXX internal state */ 1101 static Authmethod *current = NULL; 1102 static char *supported = NULL; 1103 static char *preferred = NULL; 1104 1105 /* 1106 * Given the authentication method list sent by the server, return the 1107 * next method we should try. If the server initially sends a nil list, 1108 * use a built-in default list. 1109 */ 1110 static Authmethod * 1111 authmethod_get(char *authlist) 1112 { 1113 char *name = NULL; 1114 u_int next; 1115 1116 /* Use a suitable default if we're passed a nil list. */ 1117 if (authlist == NULL || strlen(authlist) == 0) 1118 authlist = options.preferred_authentications; 1119 1120 if (supported == NULL || strcmp(authlist, supported) != 0) { 1121 debug3("start over, passed a different list %s", authlist); 1122 if (supported != NULL) 1123 xfree(supported); 1124 supported = xstrdup(authlist); 1125 preferred = options.preferred_authentications; 1126 debug3("preferred %s", preferred); 1127 current = NULL; 1128 } else if (current != NULL && authmethod_is_enabled(current)) 1129 return current; 1130 1131 for (;;) { 1132 if ((name = match_list(preferred, supported, &next)) == NULL) { 1133 debug("No more authentication methods to try."); 1134 current = NULL; 1135 return NULL; 1136 } 1137 preferred += next; 1138 debug3("authmethod_lookup %s", name); 1139 debug3("remaining preferred: %s", preferred); 1140 if ((current = authmethod_lookup(name)) != NULL && 1141 authmethod_is_enabled(current)) { 1142 debug3("authmethod_is_enabled %s", name); 1143 debug("Next authentication method: %s", name); 1144 return current; 1145 } 1146 } 1147 } 1148 1149 static char * 1150 authmethods_get(void) 1151 { 1152 Authmethod *method = NULL; 1153 Buffer b; 1154 char *list; 1155 1156 buffer_init(&b); 1157 for (method = authmethods; method->name != NULL; method++) { 1158 if (authmethod_is_enabled(method)) { 1159 if (buffer_len(&b) > 0) 1160 buffer_append(&b, ",", 1); 1161 buffer_append(&b, method->name, strlen(method->name)); 1162 } 1163 } 1164 buffer_append(&b, "\0", 1); 1165 list = xstrdup(buffer_ptr(&b)); 1166 buffer_free(&b); 1167 return list; 1168 } 1169