1 /* $OpenBSD: sshconnect2.c,v 1.174 2009/11/10 04:30:45 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "buffer.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "key.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "readconf.h" 59 #include "misc.h" 60 #include "match.h" 61 #include "dispatch.h" 62 #include "canohost.h" 63 #include "msg.h" 64 #include "pathnames.h" 65 #include "uidswap.h" 66 #include "schnorr.h" 67 #include "jpake.h" 68 69 #ifdef GSSAPI 70 #include "ssh-gss.h" 71 #endif 72 73 /* import */ 74 extern char *client_version_string; 75 extern char *server_version_string; 76 extern Options options; 77 78 /* 79 * SSH2 key exchange 80 */ 81 82 u_char *session_id2 = NULL; 83 u_int session_id2_len = 0; 84 85 char *xxx_host; 86 struct sockaddr *xxx_hostaddr; 87 88 Kex *xxx_kex = NULL; 89 90 static int 91 verify_host_key_callback(Key *hostkey) 92 { 93 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 94 fatal("Host key verification failed."); 95 return 0; 96 } 97 98 void 99 ssh_kex2(char *host, struct sockaddr *hostaddr) 100 { 101 Kex *kex; 102 103 xxx_host = host; 104 xxx_hostaddr = hostaddr; 105 106 if (options.ciphers == (char *)-1) { 107 logit("No valid ciphers for protocol version 2 given, using defaults."); 108 options.ciphers = NULL; 109 } 110 if (options.ciphers != NULL) { 111 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 112 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 113 } 114 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 115 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 116 myproposal[PROPOSAL_ENC_ALGS_STOC] = 117 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 118 if (options.compression) { 119 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 120 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 121 } else { 122 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 123 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 124 } 125 if (options.macs != NULL) { 126 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 127 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 128 } 129 if (options.hostkeyalgorithms != NULL) 130 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 131 options.hostkeyalgorithms; 132 133 if (options.rekey_limit) 134 packet_set_rekey_limit((u_int32_t)options.rekey_limit); 135 136 /* start key exchange */ 137 kex = kex_setup(myproposal); 138 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 139 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 140 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 141 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 142 kex->client_version_string=client_version_string; 143 kex->server_version_string=server_version_string; 144 kex->verify_host_key=&verify_host_key_callback; 145 146 xxx_kex = kex; 147 148 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 149 150 if (options.use_roaming && !kex->roaming) { 151 debug("Roaming not allowed by server"); 152 options.use_roaming = 0; 153 } 154 155 session_id2 = kex->session_id; 156 session_id2_len = kex->session_id_len; 157 158 #ifdef DEBUG_KEXDH 159 /* send 1st encrypted/maced/compressed message */ 160 packet_start(SSH2_MSG_IGNORE); 161 packet_put_cstring("markus"); 162 packet_send(); 163 packet_write_wait(); 164 #endif 165 } 166 167 /* 168 * Authenticate user 169 */ 170 171 typedef struct Authctxt Authctxt; 172 typedef struct Authmethod Authmethod; 173 typedef struct identity Identity; 174 typedef struct idlist Idlist; 175 176 struct identity { 177 TAILQ_ENTRY(identity) next; 178 AuthenticationConnection *ac; /* set if agent supports key */ 179 Key *key; /* public/private key */ 180 char *filename; /* comment for agent-only keys */ 181 int tried; 182 int isprivate; /* key points to the private key */ 183 }; 184 TAILQ_HEAD(idlist, identity); 185 186 struct Authctxt { 187 const char *server_user; 188 const char *local_user; 189 const char *host; 190 const char *service; 191 Authmethod *method; 192 int success; 193 char *authlist; 194 /* pubkey */ 195 Idlist keys; 196 AuthenticationConnection *agent; 197 /* hostbased */ 198 Sensitive *sensitive; 199 /* kbd-interactive */ 200 int info_req_seen; 201 /* generic */ 202 void *methoddata; 203 }; 204 struct Authmethod { 205 char *name; /* string to compare against server's list */ 206 int (*userauth)(Authctxt *authctxt); 207 void (*cleanup)(Authctxt *authctxt); 208 int *enabled; /* flag in option struct that enables method */ 209 int *batch_flag; /* flag in option struct that disables method */ 210 }; 211 212 void input_userauth_success(int, u_int32_t, void *); 213 void input_userauth_success_unexpected(int, u_int32_t, void *); 214 void input_userauth_failure(int, u_int32_t, void *); 215 void input_userauth_banner(int, u_int32_t, void *); 216 void input_userauth_error(int, u_int32_t, void *); 217 void input_userauth_info_req(int, u_int32_t, void *); 218 void input_userauth_pk_ok(int, u_int32_t, void *); 219 void input_userauth_passwd_changereq(int, u_int32_t, void *); 220 void input_userauth_jpake_server_step1(int, u_int32_t, void *); 221 void input_userauth_jpake_server_step2(int, u_int32_t, void *); 222 void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 223 224 int userauth_none(Authctxt *); 225 int userauth_pubkey(Authctxt *); 226 int userauth_passwd(Authctxt *); 227 int userauth_kbdint(Authctxt *); 228 int userauth_hostbased(Authctxt *); 229 int userauth_jpake(Authctxt *); 230 231 void userauth_jpake_cleanup(Authctxt *); 232 233 #ifdef GSSAPI 234 int userauth_gssapi(Authctxt *authctxt); 235 void input_gssapi_response(int type, u_int32_t, void *); 236 void input_gssapi_token(int type, u_int32_t, void *); 237 void input_gssapi_hash(int type, u_int32_t, void *); 238 void input_gssapi_error(int, u_int32_t, void *); 239 void input_gssapi_errtok(int, u_int32_t, void *); 240 #endif 241 242 void userauth(Authctxt *, char *); 243 244 static int sign_and_send_pubkey(Authctxt *, Identity *); 245 static void pubkey_prepare(Authctxt *); 246 static void pubkey_cleanup(Authctxt *); 247 static Key *load_identity_file(char *); 248 249 static Authmethod *authmethod_get(char *authlist); 250 static Authmethod *authmethod_lookup(const char *name); 251 static char *authmethods_get(void); 252 253 Authmethod authmethods[] = { 254 #ifdef GSSAPI 255 {"gssapi-with-mic", 256 userauth_gssapi, 257 NULL, 258 &options.gss_authentication, 259 NULL}, 260 #endif 261 {"hostbased", 262 userauth_hostbased, 263 NULL, 264 &options.hostbased_authentication, 265 NULL}, 266 {"publickey", 267 userauth_pubkey, 268 NULL, 269 &options.pubkey_authentication, 270 NULL}, 271 #ifdef JPAKE 272 {"jpake-01@openssh.com", 273 userauth_jpake, 274 userauth_jpake_cleanup, 275 &options.zero_knowledge_password_authentication, 276 &options.batch_mode}, 277 #endif 278 {"keyboard-interactive", 279 userauth_kbdint, 280 NULL, 281 &options.kbd_interactive_authentication, 282 &options.batch_mode}, 283 {"password", 284 userauth_passwd, 285 NULL, 286 &options.password_authentication, 287 &options.batch_mode}, 288 {"none", 289 userauth_none, 290 NULL, 291 NULL, 292 NULL}, 293 {NULL, NULL, NULL, NULL, NULL} 294 }; 295 296 void 297 ssh_userauth2(const char *local_user, const char *server_user, char *host, 298 Sensitive *sensitive) 299 { 300 Authctxt authctxt; 301 int type; 302 303 if (options.challenge_response_authentication) 304 options.kbd_interactive_authentication = 1; 305 306 packet_start(SSH2_MSG_SERVICE_REQUEST); 307 packet_put_cstring("ssh-userauth"); 308 packet_send(); 309 debug("SSH2_MSG_SERVICE_REQUEST sent"); 310 packet_write_wait(); 311 type = packet_read(); 312 if (type != SSH2_MSG_SERVICE_ACCEPT) 313 fatal("Server denied authentication request: %d", type); 314 if (packet_remaining() > 0) { 315 char *reply = packet_get_string(NULL); 316 debug2("service_accept: %s", reply); 317 xfree(reply); 318 } else { 319 debug2("buggy server: service_accept w/o service"); 320 } 321 packet_check_eom(); 322 debug("SSH2_MSG_SERVICE_ACCEPT received"); 323 324 if (options.preferred_authentications == NULL) 325 options.preferred_authentications = authmethods_get(); 326 327 /* setup authentication context */ 328 memset(&authctxt, 0, sizeof(authctxt)); 329 pubkey_prepare(&authctxt); 330 authctxt.server_user = server_user; 331 authctxt.local_user = local_user; 332 authctxt.host = host; 333 authctxt.service = "ssh-connection"; /* service name */ 334 authctxt.success = 0; 335 authctxt.method = authmethod_lookup("none"); 336 authctxt.authlist = NULL; 337 authctxt.methoddata = NULL; 338 authctxt.sensitive = sensitive; 339 authctxt.info_req_seen = 0; 340 if (authctxt.method == NULL) 341 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 342 343 /* initial userauth request */ 344 userauth_none(&authctxt); 345 346 dispatch_init(&input_userauth_error); 347 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 348 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 349 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 350 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 351 352 pubkey_cleanup(&authctxt); 353 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 354 355 debug("Authentication succeeded (%s).", authctxt.method->name); 356 } 357 358 void 359 userauth(Authctxt *authctxt, char *authlist) 360 { 361 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 362 authctxt->method->cleanup(authctxt); 363 364 if (authctxt->methoddata) { 365 xfree(authctxt->methoddata); 366 authctxt->methoddata = NULL; 367 } 368 if (authlist == NULL) { 369 authlist = authctxt->authlist; 370 } else { 371 if (authctxt->authlist) 372 xfree(authctxt->authlist); 373 authctxt->authlist = authlist; 374 } 375 for (;;) { 376 Authmethod *method = authmethod_get(authlist); 377 if (method == NULL) 378 fatal("Permission denied (%s).", authlist); 379 authctxt->method = method; 380 381 /* reset the per method handler */ 382 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 383 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 384 385 /* and try new method */ 386 if (method->userauth(authctxt) != 0) { 387 debug2("we sent a %s packet, wait for reply", method->name); 388 break; 389 } else { 390 debug2("we did not send a packet, disable method"); 391 method->enabled = NULL; 392 } 393 } 394 } 395 396 /* ARGSUSED */ 397 void 398 input_userauth_error(int type, u_int32_t seq, void *ctxt) 399 { 400 fatal("input_userauth_error: bad message during authentication: " 401 "type %d", type); 402 } 403 404 /* ARGSUSED */ 405 void 406 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 407 { 408 char *msg, *raw, *lang; 409 u_int len; 410 411 debug3("input_userauth_banner"); 412 raw = packet_get_string(&len); 413 lang = packet_get_string(NULL); 414 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 415 if (len > 65536) 416 len = 65536; 417 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 418 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL); 419 fprintf(stderr, "%s", msg); 420 xfree(msg); 421 } 422 xfree(raw); 423 xfree(lang); 424 } 425 426 /* ARGSUSED */ 427 void 428 input_userauth_success(int type, u_int32_t seq, void *ctxt) 429 { 430 Authctxt *authctxt = ctxt; 431 432 if (authctxt == NULL) 433 fatal("input_userauth_success: no authentication context"); 434 if (authctxt->authlist) { 435 xfree(authctxt->authlist); 436 authctxt->authlist = NULL; 437 } 438 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 439 authctxt->method->cleanup(authctxt); 440 if (authctxt->methoddata) { 441 xfree(authctxt->methoddata); 442 authctxt->methoddata = NULL; 443 } 444 authctxt->success = 1; /* break out */ 445 } 446 447 void 448 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 449 { 450 Authctxt *authctxt = ctxt; 451 452 if (authctxt == NULL) 453 fatal("%s: no authentication context", __func__); 454 455 fatal("Unexpected authentication success during %s.", 456 authctxt->method->name); 457 } 458 459 /* ARGSUSED */ 460 void 461 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 462 { 463 Authctxt *authctxt = ctxt; 464 char *authlist = NULL; 465 int partial; 466 467 if (authctxt == NULL) 468 fatal("input_userauth_failure: no authentication context"); 469 470 authlist = packet_get_string(NULL); 471 partial = packet_get_char(); 472 packet_check_eom(); 473 474 if (partial != 0) 475 logit("Authenticated with partial success."); 476 debug("Authentications that can continue: %s", authlist); 477 478 userauth(authctxt, authlist); 479 } 480 481 /* ARGSUSED */ 482 void 483 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 484 { 485 Authctxt *authctxt = ctxt; 486 Key *key = NULL; 487 Identity *id = NULL; 488 Buffer b; 489 int pktype, sent = 0; 490 u_int alen, blen; 491 char *pkalg, *fp; 492 u_char *pkblob; 493 494 if (authctxt == NULL) 495 fatal("input_userauth_pk_ok: no authentication context"); 496 if (datafellows & SSH_BUG_PKOK) { 497 /* this is similar to SSH_BUG_PKAUTH */ 498 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 499 pkblob = packet_get_string(&blen); 500 buffer_init(&b); 501 buffer_append(&b, pkblob, blen); 502 pkalg = buffer_get_string(&b, &alen); 503 buffer_free(&b); 504 } else { 505 pkalg = packet_get_string(&alen); 506 pkblob = packet_get_string(&blen); 507 } 508 packet_check_eom(); 509 510 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 511 512 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 513 debug("unknown pkalg %s", pkalg); 514 goto done; 515 } 516 if ((key = key_from_blob(pkblob, blen)) == NULL) { 517 debug("no key from blob. pkalg %s", pkalg); 518 goto done; 519 } 520 if (key->type != pktype) { 521 error("input_userauth_pk_ok: type mismatch " 522 "for decoded key (received %d, expected %d)", 523 key->type, pktype); 524 goto done; 525 } 526 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 527 debug2("input_userauth_pk_ok: fp %s", fp); 528 xfree(fp); 529 530 /* 531 * search keys in the reverse order, because last candidate has been 532 * moved to the end of the queue. this also avoids confusion by 533 * duplicate keys 534 */ 535 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 536 if (key_equal(key, id->key)) { 537 sent = sign_and_send_pubkey(authctxt, id); 538 break; 539 } 540 } 541 done: 542 if (key != NULL) 543 key_free(key); 544 xfree(pkalg); 545 xfree(pkblob); 546 547 /* try another method if we did not send a packet */ 548 if (sent == 0) 549 userauth(authctxt, NULL); 550 } 551 552 #ifdef GSSAPI 553 int 554 userauth_gssapi(Authctxt *authctxt) 555 { 556 Gssctxt *gssctxt = NULL; 557 static gss_OID_set gss_supported = NULL; 558 static u_int mech = 0; 559 OM_uint32 min; 560 int ok = 0; 561 562 /* Try one GSSAPI method at a time, rather than sending them all at 563 * once. */ 564 565 if (gss_supported == NULL) 566 gss_indicate_mechs(&min, &gss_supported); 567 568 /* Check to see if the mechanism is usable before we offer it */ 569 while (mech < gss_supported->count && !ok) { 570 /* My DER encoding requires length<128 */ 571 if (gss_supported->elements[mech].length < 128 && 572 ssh_gssapi_check_mechanism(&gssctxt, 573 &gss_supported->elements[mech], authctxt->host)) { 574 ok = 1; /* Mechanism works */ 575 } else { 576 mech++; 577 } 578 } 579 580 if (!ok) 581 return 0; 582 583 authctxt->methoddata=(void *)gssctxt; 584 585 packet_start(SSH2_MSG_USERAUTH_REQUEST); 586 packet_put_cstring(authctxt->server_user); 587 packet_put_cstring(authctxt->service); 588 packet_put_cstring(authctxt->method->name); 589 590 packet_put_int(1); 591 592 packet_put_int((gss_supported->elements[mech].length) + 2); 593 packet_put_char(SSH_GSS_OIDTYPE); 594 packet_put_char(gss_supported->elements[mech].length); 595 packet_put_raw(gss_supported->elements[mech].elements, 596 gss_supported->elements[mech].length); 597 598 packet_send(); 599 600 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 601 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 602 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 603 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 604 605 mech++; /* Move along to next candidate */ 606 607 return 1; 608 } 609 610 static OM_uint32 611 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 612 { 613 Authctxt *authctxt = ctxt; 614 Gssctxt *gssctxt = authctxt->methoddata; 615 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 616 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 617 gss_buffer_desc gssbuf; 618 OM_uint32 status, ms, flags; 619 Buffer b; 620 621 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 622 recv_tok, &send_tok, &flags); 623 624 if (send_tok.length > 0) { 625 if (GSS_ERROR(status)) 626 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 627 else 628 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 629 630 packet_put_string(send_tok.value, send_tok.length); 631 packet_send(); 632 gss_release_buffer(&ms, &send_tok); 633 } 634 635 if (status == GSS_S_COMPLETE) { 636 /* send either complete or MIC, depending on mechanism */ 637 if (!(flags & GSS_C_INTEG_FLAG)) { 638 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 639 packet_send(); 640 } else { 641 ssh_gssapi_buildmic(&b, authctxt->server_user, 642 authctxt->service, "gssapi-with-mic"); 643 644 gssbuf.value = buffer_ptr(&b); 645 gssbuf.length = buffer_len(&b); 646 647 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 648 649 if (!GSS_ERROR(status)) { 650 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 651 packet_put_string(mic.value, mic.length); 652 653 packet_send(); 654 } 655 656 buffer_free(&b); 657 gss_release_buffer(&ms, &mic); 658 } 659 } 660 661 return status; 662 } 663 664 /* ARGSUSED */ 665 void 666 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 667 { 668 Authctxt *authctxt = ctxt; 669 Gssctxt *gssctxt; 670 int oidlen; 671 char *oidv; 672 673 if (authctxt == NULL) 674 fatal("input_gssapi_response: no authentication context"); 675 gssctxt = authctxt->methoddata; 676 677 /* Setup our OID */ 678 oidv = packet_get_string(&oidlen); 679 680 if (oidlen <= 2 || 681 oidv[0] != SSH_GSS_OIDTYPE || 682 oidv[1] != oidlen - 2) { 683 xfree(oidv); 684 debug("Badly encoded mechanism OID received"); 685 userauth(authctxt, NULL); 686 return; 687 } 688 689 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 690 fatal("Server returned different OID than expected"); 691 692 packet_check_eom(); 693 694 xfree(oidv); 695 696 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 697 /* Start again with next method on list */ 698 debug("Trying to start again"); 699 userauth(authctxt, NULL); 700 return; 701 } 702 } 703 704 /* ARGSUSED */ 705 void 706 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 707 { 708 Authctxt *authctxt = ctxt; 709 gss_buffer_desc recv_tok; 710 OM_uint32 status; 711 u_int slen; 712 713 if (authctxt == NULL) 714 fatal("input_gssapi_response: no authentication context"); 715 716 recv_tok.value = packet_get_string(&slen); 717 recv_tok.length = slen; /* safe typecast */ 718 719 packet_check_eom(); 720 721 status = process_gssapi_token(ctxt, &recv_tok); 722 723 xfree(recv_tok.value); 724 725 if (GSS_ERROR(status)) { 726 /* Start again with the next method in the list */ 727 userauth(authctxt, NULL); 728 return; 729 } 730 } 731 732 /* ARGSUSED */ 733 void 734 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 735 { 736 Authctxt *authctxt = ctxt; 737 Gssctxt *gssctxt; 738 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 739 gss_buffer_desc recv_tok; 740 OM_uint32 status, ms; 741 u_int len; 742 743 if (authctxt == NULL) 744 fatal("input_gssapi_response: no authentication context"); 745 gssctxt = authctxt->methoddata; 746 747 recv_tok.value = packet_get_string(&len); 748 recv_tok.length = len; 749 750 packet_check_eom(); 751 752 /* Stick it into GSSAPI and see what it says */ 753 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 754 &recv_tok, &send_tok, NULL); 755 756 xfree(recv_tok.value); 757 gss_release_buffer(&ms, &send_tok); 758 759 /* Server will be returning a failed packet after this one */ 760 } 761 762 /* ARGSUSED */ 763 void 764 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 765 { 766 OM_uint32 maj, min; 767 char *msg; 768 char *lang; 769 770 maj=packet_get_int(); 771 min=packet_get_int(); 772 msg=packet_get_string(NULL); 773 lang=packet_get_string(NULL); 774 775 packet_check_eom(); 776 777 debug("Server GSSAPI Error:\n%s", msg); 778 xfree(msg); 779 xfree(lang); 780 } 781 #endif /* GSSAPI */ 782 783 int 784 userauth_none(Authctxt *authctxt) 785 { 786 /* initial userauth request */ 787 packet_start(SSH2_MSG_USERAUTH_REQUEST); 788 packet_put_cstring(authctxt->server_user); 789 packet_put_cstring(authctxt->service); 790 packet_put_cstring(authctxt->method->name); 791 packet_send(); 792 return 1; 793 } 794 795 int 796 userauth_passwd(Authctxt *authctxt) 797 { 798 static int attempt = 0; 799 char prompt[150]; 800 char *password; 801 802 if (attempt++ >= options.number_of_password_prompts) 803 return 0; 804 805 if (attempt != 1) 806 error("Permission denied, please try again."); 807 808 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 809 authctxt->server_user, authctxt->host); 810 password = read_passphrase(prompt, 0); 811 packet_start(SSH2_MSG_USERAUTH_REQUEST); 812 packet_put_cstring(authctxt->server_user); 813 packet_put_cstring(authctxt->service); 814 packet_put_cstring(authctxt->method->name); 815 packet_put_char(0); 816 packet_put_cstring(password); 817 memset(password, 0, strlen(password)); 818 xfree(password); 819 packet_add_padding(64); 820 packet_send(); 821 822 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 823 &input_userauth_passwd_changereq); 824 825 return 1; 826 } 827 828 /* 829 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 830 */ 831 /* ARGSUSED */ 832 void 833 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 834 { 835 Authctxt *authctxt = ctxt; 836 char *info, *lang, *password = NULL, *retype = NULL; 837 char prompt[150]; 838 839 debug2("input_userauth_passwd_changereq"); 840 841 if (authctxt == NULL) 842 fatal("input_userauth_passwd_changereq: " 843 "no authentication context"); 844 845 info = packet_get_string(NULL); 846 lang = packet_get_string(NULL); 847 if (strlen(info) > 0) 848 logit("%s", info); 849 xfree(info); 850 xfree(lang); 851 packet_start(SSH2_MSG_USERAUTH_REQUEST); 852 packet_put_cstring(authctxt->server_user); 853 packet_put_cstring(authctxt->service); 854 packet_put_cstring(authctxt->method->name); 855 packet_put_char(1); /* additional info */ 856 snprintf(prompt, sizeof(prompt), 857 "Enter %.30s@%.128s's old password: ", 858 authctxt->server_user, authctxt->host); 859 password = read_passphrase(prompt, 0); 860 packet_put_cstring(password); 861 memset(password, 0, strlen(password)); 862 xfree(password); 863 password = NULL; 864 while (password == NULL) { 865 snprintf(prompt, sizeof(prompt), 866 "Enter %.30s@%.128s's new password: ", 867 authctxt->server_user, authctxt->host); 868 password = read_passphrase(prompt, RP_ALLOW_EOF); 869 if (password == NULL) { 870 /* bail out */ 871 return; 872 } 873 snprintf(prompt, sizeof(prompt), 874 "Retype %.30s@%.128s's new password: ", 875 authctxt->server_user, authctxt->host); 876 retype = read_passphrase(prompt, 0); 877 if (strcmp(password, retype) != 0) { 878 memset(password, 0, strlen(password)); 879 xfree(password); 880 logit("Mismatch; try again, EOF to quit."); 881 password = NULL; 882 } 883 memset(retype, 0, strlen(retype)); 884 xfree(retype); 885 } 886 packet_put_cstring(password); 887 memset(password, 0, strlen(password)); 888 xfree(password); 889 packet_add_padding(64); 890 packet_send(); 891 892 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 893 &input_userauth_passwd_changereq); 894 } 895 896 #ifdef JPAKE 897 static char * 898 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 899 { 900 /* OpenBSD crypt(3) handles all of these */ 901 if (strcmp(crypt_scheme, "crypt") == 0 || 902 strcmp(crypt_scheme, "bcrypt") == 0 || 903 strcmp(crypt_scheme, "md5crypt") == 0 || 904 strcmp(crypt_scheme, "crypt-extended") == 0) 905 return xstrdup(crypt(password, salt)); 906 error("%s: unsupported password encryption scheme \"%.100s\"", 907 __func__, crypt_scheme); 908 return NULL; 909 } 910 911 static BIGNUM * 912 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 913 const char *salt) 914 { 915 char prompt[256], *password, *crypted; 916 u_char *secret; 917 u_int secret_len; 918 BIGNUM *ret; 919 920 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 921 authctxt->server_user, authctxt->host); 922 password = read_passphrase(prompt, 0); 923 924 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 925 logit("Disabling %s authentication", authctxt->method->name); 926 authctxt->method->enabled = NULL; 927 /* Continue with an empty password to fail gracefully */ 928 crypted = xstrdup(""); 929 } 930 931 #ifdef JPAKE_DEBUG 932 debug3("%s: salt = %s", __func__, salt); 933 debug3("%s: scheme = %s", __func__, crypt_scheme); 934 debug3("%s: crypted = %s", __func__, crypted); 935 #endif 936 937 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 938 &secret, &secret_len) != 0) 939 fatal("%s: hash_buffer", __func__); 940 941 bzero(password, strlen(password)); 942 bzero(crypted, strlen(crypted)); 943 xfree(password); 944 xfree(crypted); 945 946 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 947 fatal("%s: BN_bin2bn (secret)", __func__); 948 bzero(secret, secret_len); 949 xfree(secret); 950 951 return ret; 952 } 953 954 /* ARGSUSED */ 955 void 956 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 957 { 958 Authctxt *authctxt = ctxt; 959 struct jpake_ctx *pctx = authctxt->methoddata; 960 u_char *x3_proof, *x4_proof, *x2_s_proof; 961 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 962 char *crypt_scheme, *salt; 963 964 /* Disable this message */ 965 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 966 967 if ((pctx->g_x3 = BN_new()) == NULL || 968 (pctx->g_x4 = BN_new()) == NULL) 969 fatal("%s: BN_new", __func__); 970 971 /* Fetch step 1 values */ 972 crypt_scheme = packet_get_string(NULL); 973 salt = packet_get_string(NULL); 974 pctx->server_id = packet_get_string(&pctx->server_id_len); 975 packet_get_bignum2(pctx->g_x3); 976 packet_get_bignum2(pctx->g_x4); 977 x3_proof = packet_get_string(&x3_proof_len); 978 x4_proof = packet_get_string(&x4_proof_len); 979 packet_check_eom(); 980 981 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 982 983 /* Obtain password and derive secret */ 984 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 985 bzero(crypt_scheme, strlen(crypt_scheme)); 986 bzero(salt, strlen(salt)); 987 xfree(crypt_scheme); 988 xfree(salt); 989 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 990 991 /* Calculate step 2 values */ 992 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 993 pctx->g_x3, pctx->g_x4, pctx->x2, 994 pctx->server_id, pctx->server_id_len, 995 pctx->client_id, pctx->client_id_len, 996 x3_proof, x3_proof_len, 997 x4_proof, x4_proof_len, 998 &pctx->a, 999 &x2_s_proof, &x2_s_proof_len); 1000 1001 bzero(x3_proof, x3_proof_len); 1002 bzero(x4_proof, x4_proof_len); 1003 xfree(x3_proof); 1004 xfree(x4_proof); 1005 1006 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1007 1008 /* Send values for step 2 */ 1009 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1010 packet_put_bignum2(pctx->a); 1011 packet_put_string(x2_s_proof, x2_s_proof_len); 1012 packet_send(); 1013 1014 bzero(x2_s_proof, x2_s_proof_len); 1015 xfree(x2_s_proof); 1016 1017 /* Expect step 2 packet from peer */ 1018 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1019 input_userauth_jpake_server_step2); 1020 } 1021 1022 /* ARGSUSED */ 1023 void 1024 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1025 { 1026 Authctxt *authctxt = ctxt; 1027 struct jpake_ctx *pctx = authctxt->methoddata; 1028 u_char *x4_s_proof; 1029 u_int x4_s_proof_len; 1030 1031 /* Disable this message */ 1032 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1033 1034 if ((pctx->b = BN_new()) == NULL) 1035 fatal("%s: BN_new", __func__); 1036 1037 /* Fetch step 2 values */ 1038 packet_get_bignum2(pctx->b); 1039 x4_s_proof = packet_get_string(&x4_s_proof_len); 1040 packet_check_eom(); 1041 1042 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1043 1044 /* Derive shared key and calculate confirmation hash */ 1045 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1046 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1047 pctx->client_id, pctx->client_id_len, 1048 pctx->server_id, pctx->server_id_len, 1049 session_id2, session_id2_len, 1050 x4_s_proof, x4_s_proof_len, 1051 &pctx->k, 1052 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1053 1054 bzero(x4_s_proof, x4_s_proof_len); 1055 xfree(x4_s_proof); 1056 1057 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1058 1059 /* Send key confirmation proof */ 1060 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1061 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1062 packet_send(); 1063 1064 /* Expect confirmation from peer */ 1065 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1066 input_userauth_jpake_server_confirm); 1067 } 1068 1069 /* ARGSUSED */ 1070 void 1071 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1072 { 1073 Authctxt *authctxt = ctxt; 1074 struct jpake_ctx *pctx = authctxt->methoddata; 1075 1076 /* Disable this message */ 1077 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1078 1079 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1080 packet_check_eom(); 1081 1082 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1083 1084 /* Verify expected confirmation hash */ 1085 if (jpake_check_confirm(pctx->k, 1086 pctx->server_id, pctx->server_id_len, 1087 session_id2, session_id2_len, 1088 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1089 debug("%s: %s success", __func__, authctxt->method->name); 1090 else { 1091 debug("%s: confirmation mismatch", __func__); 1092 /* XXX stash this so if auth succeeds then we can warn/kill */ 1093 } 1094 1095 userauth_jpake_cleanup(authctxt); 1096 } 1097 #endif /* JPAKE */ 1098 1099 static int 1100 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1101 u_char *data, u_int datalen) 1102 { 1103 Key *prv; 1104 int ret; 1105 1106 /* the agent supports this key */ 1107 if (id->ac) 1108 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1109 data, datalen)); 1110 /* 1111 * we have already loaded the private key or 1112 * the private key is stored in external hardware 1113 */ 1114 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1115 return (key_sign(id->key, sigp, lenp, data, datalen)); 1116 /* load the private key from the file */ 1117 if ((prv = load_identity_file(id->filename)) == NULL) 1118 return (-1); 1119 ret = key_sign(prv, sigp, lenp, data, datalen); 1120 key_free(prv); 1121 return (ret); 1122 } 1123 1124 static int 1125 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1126 { 1127 Buffer b; 1128 u_char *blob, *signature; 1129 u_int bloblen, slen; 1130 u_int skip = 0; 1131 int ret = -1; 1132 int have_sig = 1; 1133 1134 debug3("sign_and_send_pubkey"); 1135 1136 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1137 /* we cannot handle this key */ 1138 debug3("sign_and_send_pubkey: cannot handle key"); 1139 return 0; 1140 } 1141 /* data to be signed */ 1142 buffer_init(&b); 1143 if (datafellows & SSH_OLD_SESSIONID) { 1144 buffer_append(&b, session_id2, session_id2_len); 1145 skip = session_id2_len; 1146 } else { 1147 buffer_put_string(&b, session_id2, session_id2_len); 1148 skip = buffer_len(&b); 1149 } 1150 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1151 buffer_put_cstring(&b, authctxt->server_user); 1152 buffer_put_cstring(&b, 1153 datafellows & SSH_BUG_PKSERVICE ? 1154 "ssh-userauth" : 1155 authctxt->service); 1156 if (datafellows & SSH_BUG_PKAUTH) { 1157 buffer_put_char(&b, have_sig); 1158 } else { 1159 buffer_put_cstring(&b, authctxt->method->name); 1160 buffer_put_char(&b, have_sig); 1161 buffer_put_cstring(&b, key_ssh_name(id->key)); 1162 } 1163 buffer_put_string(&b, blob, bloblen); 1164 1165 /* generate signature */ 1166 ret = identity_sign(id, &signature, &slen, 1167 buffer_ptr(&b), buffer_len(&b)); 1168 if (ret == -1) { 1169 xfree(blob); 1170 buffer_free(&b); 1171 return 0; 1172 } 1173 #ifdef DEBUG_PK 1174 buffer_dump(&b); 1175 #endif 1176 if (datafellows & SSH_BUG_PKSERVICE) { 1177 buffer_clear(&b); 1178 buffer_append(&b, session_id2, session_id2_len); 1179 skip = session_id2_len; 1180 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1181 buffer_put_cstring(&b, authctxt->server_user); 1182 buffer_put_cstring(&b, authctxt->service); 1183 buffer_put_cstring(&b, authctxt->method->name); 1184 buffer_put_char(&b, have_sig); 1185 if (!(datafellows & SSH_BUG_PKAUTH)) 1186 buffer_put_cstring(&b, key_ssh_name(id->key)); 1187 buffer_put_string(&b, blob, bloblen); 1188 } 1189 xfree(blob); 1190 1191 /* append signature */ 1192 buffer_put_string(&b, signature, slen); 1193 xfree(signature); 1194 1195 /* skip session id and packet type */ 1196 if (buffer_len(&b) < skip + 1) 1197 fatal("userauth_pubkey: internal error"); 1198 buffer_consume(&b, skip + 1); 1199 1200 /* put remaining data from buffer into packet */ 1201 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1202 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1203 buffer_free(&b); 1204 packet_send(); 1205 1206 return 1; 1207 } 1208 1209 static int 1210 send_pubkey_test(Authctxt *authctxt, Identity *id) 1211 { 1212 u_char *blob; 1213 u_int bloblen, have_sig = 0; 1214 1215 debug3("send_pubkey_test"); 1216 1217 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1218 /* we cannot handle this key */ 1219 debug3("send_pubkey_test: cannot handle key"); 1220 return 0; 1221 } 1222 /* register callback for USERAUTH_PK_OK message */ 1223 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1224 1225 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1226 packet_put_cstring(authctxt->server_user); 1227 packet_put_cstring(authctxt->service); 1228 packet_put_cstring(authctxt->method->name); 1229 packet_put_char(have_sig); 1230 if (!(datafellows & SSH_BUG_PKAUTH)) 1231 packet_put_cstring(key_ssh_name(id->key)); 1232 packet_put_string(blob, bloblen); 1233 xfree(blob); 1234 packet_send(); 1235 return 1; 1236 } 1237 1238 static Key * 1239 load_identity_file(char *filename) 1240 { 1241 Key *private; 1242 char prompt[300], *passphrase; 1243 int perm_ok, quit, i; 1244 struct stat st; 1245 1246 if (stat(filename, &st) < 0) { 1247 debug3("no such identity: %s", filename); 1248 return NULL; 1249 } 1250 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1251 if (!perm_ok) 1252 return NULL; 1253 if (private == NULL) { 1254 if (options.batch_mode) 1255 return NULL; 1256 snprintf(prompt, sizeof prompt, 1257 "Enter passphrase for key '%.100s': ", filename); 1258 for (i = 0; i < options.number_of_password_prompts; i++) { 1259 passphrase = read_passphrase(prompt, 0); 1260 if (strcmp(passphrase, "") != 0) { 1261 private = key_load_private_type(KEY_UNSPEC, 1262 filename, passphrase, NULL, NULL); 1263 quit = 0; 1264 } else { 1265 debug2("no passphrase given, try next key"); 1266 quit = 1; 1267 } 1268 memset(passphrase, 0, strlen(passphrase)); 1269 xfree(passphrase); 1270 if (private != NULL || quit) 1271 break; 1272 debug2("bad passphrase given, try again..."); 1273 } 1274 } 1275 return private; 1276 } 1277 1278 /* 1279 * try keys in the following order: 1280 * 1. agent keys that are found in the config file 1281 * 2. other agent keys 1282 * 3. keys that are only listed in the config file 1283 */ 1284 static void 1285 pubkey_prepare(Authctxt *authctxt) 1286 { 1287 Identity *id; 1288 Idlist agent, files, *preferred; 1289 Key *key; 1290 AuthenticationConnection *ac; 1291 char *comment; 1292 int i, found; 1293 1294 TAILQ_INIT(&agent); /* keys from the agent */ 1295 TAILQ_INIT(&files); /* keys from the config file */ 1296 preferred = &authctxt->keys; 1297 TAILQ_INIT(preferred); /* preferred order of keys */ 1298 1299 /* list of keys stored in the filesystem */ 1300 for (i = 0; i < options.num_identity_files; i++) { 1301 key = options.identity_keys[i]; 1302 if (key && key->type == KEY_RSA1) 1303 continue; 1304 options.identity_keys[i] = NULL; 1305 id = xcalloc(1, sizeof(*id)); 1306 id->key = key; 1307 id->filename = xstrdup(options.identity_files[i]); 1308 TAILQ_INSERT_TAIL(&files, id, next); 1309 } 1310 /* list of keys supported by the agent */ 1311 if ((ac = ssh_get_authentication_connection())) { 1312 for (key = ssh_get_first_identity(ac, &comment, 2); 1313 key != NULL; 1314 key = ssh_get_next_identity(ac, &comment, 2)) { 1315 found = 0; 1316 TAILQ_FOREACH(id, &files, next) { 1317 /* agent keys from the config file are preferred */ 1318 if (key_equal(key, id->key)) { 1319 key_free(key); 1320 xfree(comment); 1321 TAILQ_REMOVE(&files, id, next); 1322 TAILQ_INSERT_TAIL(preferred, id, next); 1323 id->ac = ac; 1324 found = 1; 1325 break; 1326 } 1327 } 1328 if (!found && !options.identities_only) { 1329 id = xcalloc(1, sizeof(*id)); 1330 id->key = key; 1331 id->filename = comment; 1332 id->ac = ac; 1333 TAILQ_INSERT_TAIL(&agent, id, next); 1334 } 1335 } 1336 /* append remaining agent keys */ 1337 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1338 TAILQ_REMOVE(&agent, id, next); 1339 TAILQ_INSERT_TAIL(preferred, id, next); 1340 } 1341 authctxt->agent = ac; 1342 } 1343 /* append remaining keys from the config file */ 1344 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1345 TAILQ_REMOVE(&files, id, next); 1346 TAILQ_INSERT_TAIL(preferred, id, next); 1347 } 1348 TAILQ_FOREACH(id, preferred, next) { 1349 debug2("key: %s (%p)", id->filename, id->key); 1350 } 1351 } 1352 1353 static void 1354 pubkey_cleanup(Authctxt *authctxt) 1355 { 1356 Identity *id; 1357 1358 if (authctxt->agent != NULL) 1359 ssh_close_authentication_connection(authctxt->agent); 1360 for (id = TAILQ_FIRST(&authctxt->keys); id; 1361 id = TAILQ_FIRST(&authctxt->keys)) { 1362 TAILQ_REMOVE(&authctxt->keys, id, next); 1363 if (id->key) 1364 key_free(id->key); 1365 if (id->filename) 1366 xfree(id->filename); 1367 xfree(id); 1368 } 1369 } 1370 1371 int 1372 userauth_pubkey(Authctxt *authctxt) 1373 { 1374 Identity *id; 1375 int sent = 0; 1376 1377 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1378 if (id->tried++) 1379 return (0); 1380 /* move key to the end of the queue */ 1381 TAILQ_REMOVE(&authctxt->keys, id, next); 1382 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1383 /* 1384 * send a test message if we have the public key. for 1385 * encrypted keys we cannot do this and have to load the 1386 * private key instead 1387 */ 1388 if (id->key && id->key->type != KEY_RSA1) { 1389 debug("Offering public key: %s", id->filename); 1390 sent = send_pubkey_test(authctxt, id); 1391 } else if (id->key == NULL) { 1392 debug("Trying private key: %s", id->filename); 1393 id->key = load_identity_file(id->filename); 1394 if (id->key != NULL) { 1395 id->isprivate = 1; 1396 sent = sign_and_send_pubkey(authctxt, id); 1397 key_free(id->key); 1398 id->key = NULL; 1399 } 1400 } 1401 if (sent) 1402 return (sent); 1403 } 1404 return (0); 1405 } 1406 1407 /* 1408 * Send userauth request message specifying keyboard-interactive method. 1409 */ 1410 int 1411 userauth_kbdint(Authctxt *authctxt) 1412 { 1413 static int attempt = 0; 1414 1415 if (attempt++ >= options.number_of_password_prompts) 1416 return 0; 1417 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1418 if (attempt > 1 && !authctxt->info_req_seen) { 1419 debug3("userauth_kbdint: disable: no info_req_seen"); 1420 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1421 return 0; 1422 } 1423 1424 debug2("userauth_kbdint"); 1425 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1426 packet_put_cstring(authctxt->server_user); 1427 packet_put_cstring(authctxt->service); 1428 packet_put_cstring(authctxt->method->name); 1429 packet_put_cstring(""); /* lang */ 1430 packet_put_cstring(options.kbd_interactive_devices ? 1431 options.kbd_interactive_devices : ""); 1432 packet_send(); 1433 1434 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1435 return 1; 1436 } 1437 1438 /* 1439 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1440 */ 1441 void 1442 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1443 { 1444 Authctxt *authctxt = ctxt; 1445 char *name, *inst, *lang, *prompt, *response; 1446 u_int num_prompts, i; 1447 int echo = 0; 1448 1449 debug2("input_userauth_info_req"); 1450 1451 if (authctxt == NULL) 1452 fatal("input_userauth_info_req: no authentication context"); 1453 1454 authctxt->info_req_seen = 1; 1455 1456 name = packet_get_string(NULL); 1457 inst = packet_get_string(NULL); 1458 lang = packet_get_string(NULL); 1459 if (strlen(name) > 0) 1460 logit("%s", name); 1461 if (strlen(inst) > 0) 1462 logit("%s", inst); 1463 xfree(name); 1464 xfree(inst); 1465 xfree(lang); 1466 1467 num_prompts = packet_get_int(); 1468 /* 1469 * Begin to build info response packet based on prompts requested. 1470 * We commit to providing the correct number of responses, so if 1471 * further on we run into a problem that prevents this, we have to 1472 * be sure and clean this up and send a correct error response. 1473 */ 1474 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1475 packet_put_int(num_prompts); 1476 1477 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1478 for (i = 0; i < num_prompts; i++) { 1479 prompt = packet_get_string(NULL); 1480 echo = packet_get_char(); 1481 1482 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1483 1484 packet_put_cstring(response); 1485 memset(response, 0, strlen(response)); 1486 xfree(response); 1487 xfree(prompt); 1488 } 1489 packet_check_eom(); /* done with parsing incoming message. */ 1490 1491 packet_add_padding(64); 1492 packet_send(); 1493 } 1494 1495 static int 1496 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1497 u_char *data, u_int datalen) 1498 { 1499 Buffer b; 1500 struct stat st; 1501 pid_t pid; 1502 int to[2], from[2], status, version = 2; 1503 1504 debug2("ssh_keysign called"); 1505 1506 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1507 error("ssh_keysign: no installed: %s", strerror(errno)); 1508 return -1; 1509 } 1510 if (fflush(stdout) != 0) 1511 error("ssh_keysign: fflush: %s", strerror(errno)); 1512 if (pipe(to) < 0) { 1513 error("ssh_keysign: pipe: %s", strerror(errno)); 1514 return -1; 1515 } 1516 if (pipe(from) < 0) { 1517 error("ssh_keysign: pipe: %s", strerror(errno)); 1518 return -1; 1519 } 1520 if ((pid = fork()) < 0) { 1521 error("ssh_keysign: fork: %s", strerror(errno)); 1522 return -1; 1523 } 1524 if (pid == 0) { 1525 /* keep the socket on exec */ 1526 fcntl(packet_get_connection_in(), F_SETFD, 0); 1527 permanently_drop_suid(getuid()); 1528 close(from[0]); 1529 if (dup2(from[1], STDOUT_FILENO) < 0) 1530 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1531 close(to[1]); 1532 if (dup2(to[0], STDIN_FILENO) < 0) 1533 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1534 close(from[1]); 1535 close(to[0]); 1536 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1537 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1538 strerror(errno)); 1539 } 1540 close(from[1]); 1541 close(to[0]); 1542 1543 buffer_init(&b); 1544 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1545 buffer_put_string(&b, data, datalen); 1546 if (ssh_msg_send(to[1], version, &b) == -1) 1547 fatal("ssh_keysign: couldn't send request"); 1548 1549 if (ssh_msg_recv(from[0], &b) < 0) { 1550 error("ssh_keysign: no reply"); 1551 buffer_free(&b); 1552 return -1; 1553 } 1554 close(from[0]); 1555 close(to[1]); 1556 1557 while (waitpid(pid, &status, 0) < 0) 1558 if (errno != EINTR) 1559 break; 1560 1561 if (buffer_get_char(&b) != version) { 1562 error("ssh_keysign: bad version"); 1563 buffer_free(&b); 1564 return -1; 1565 } 1566 *sigp = buffer_get_string(&b, lenp); 1567 buffer_free(&b); 1568 1569 return 0; 1570 } 1571 1572 int 1573 userauth_hostbased(Authctxt *authctxt) 1574 { 1575 Key *private = NULL; 1576 Sensitive *sensitive = authctxt->sensitive; 1577 Buffer b; 1578 u_char *signature, *blob; 1579 char *chost, *pkalg, *p, myname[NI_MAXHOST]; 1580 const char *service; 1581 u_int blen, slen; 1582 int ok, i, len, found = 0; 1583 1584 /* check for a useful key */ 1585 for (i = 0; i < sensitive->nkeys; i++) { 1586 private = sensitive->keys[i]; 1587 if (private && private->type != KEY_RSA1) { 1588 found = 1; 1589 /* we take and free the key */ 1590 sensitive->keys[i] = NULL; 1591 break; 1592 } 1593 } 1594 if (!found) { 1595 debug("No more client hostkeys for hostbased authentication."); 1596 return 0; 1597 } 1598 if (key_to_blob(private, &blob, &blen) == 0) { 1599 key_free(private); 1600 return 0; 1601 } 1602 /* figure out a name for the client host */ 1603 p = NULL; 1604 if (packet_connection_is_on_socket()) 1605 p = get_local_name(packet_get_connection_in()); 1606 if (p == NULL) { 1607 if (gethostname(myname, sizeof(myname)) == -1) { 1608 verbose("userauth_hostbased: gethostname: %s", 1609 strerror(errno)); 1610 } else 1611 p = xstrdup(myname); 1612 } 1613 if (p == NULL) { 1614 error("userauth_hostbased: cannot get local ipaddr/name"); 1615 key_free(private); 1616 xfree(blob); 1617 return 0; 1618 } 1619 len = strlen(p) + 2; 1620 xasprintf(&chost, "%s.", p); 1621 debug2("userauth_hostbased: chost %s", chost); 1622 xfree(p); 1623 1624 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1625 authctxt->service; 1626 pkalg = xstrdup(key_ssh_name(private)); 1627 buffer_init(&b); 1628 /* construct data */ 1629 buffer_put_string(&b, session_id2, session_id2_len); 1630 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1631 buffer_put_cstring(&b, authctxt->server_user); 1632 buffer_put_cstring(&b, service); 1633 buffer_put_cstring(&b, authctxt->method->name); 1634 buffer_put_cstring(&b, pkalg); 1635 buffer_put_string(&b, blob, blen); 1636 buffer_put_cstring(&b, chost); 1637 buffer_put_cstring(&b, authctxt->local_user); 1638 #ifdef DEBUG_PK 1639 buffer_dump(&b); 1640 #endif 1641 if (sensitive->external_keysign) 1642 ok = ssh_keysign(private, &signature, &slen, 1643 buffer_ptr(&b), buffer_len(&b)); 1644 else 1645 ok = key_sign(private, &signature, &slen, 1646 buffer_ptr(&b), buffer_len(&b)); 1647 key_free(private); 1648 buffer_free(&b); 1649 if (ok != 0) { 1650 error("key_sign failed"); 1651 xfree(chost); 1652 xfree(pkalg); 1653 xfree(blob); 1654 return 0; 1655 } 1656 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1657 packet_put_cstring(authctxt->server_user); 1658 packet_put_cstring(authctxt->service); 1659 packet_put_cstring(authctxt->method->name); 1660 packet_put_cstring(pkalg); 1661 packet_put_string(blob, blen); 1662 packet_put_cstring(chost); 1663 packet_put_cstring(authctxt->local_user); 1664 packet_put_string(signature, slen); 1665 memset(signature, 's', slen); 1666 xfree(signature); 1667 xfree(chost); 1668 xfree(pkalg); 1669 xfree(blob); 1670 1671 packet_send(); 1672 return 1; 1673 } 1674 1675 #ifdef JPAKE 1676 int 1677 userauth_jpake(Authctxt *authctxt) 1678 { 1679 struct jpake_ctx *pctx; 1680 u_char *x1_proof, *x2_proof; 1681 u_int x1_proof_len, x2_proof_len; 1682 static int attempt = 0; /* XXX share with userauth_password's? */ 1683 1684 if (attempt++ >= options.number_of_password_prompts) 1685 return 0; 1686 if (attempt != 1) 1687 error("Permission denied, please try again."); 1688 1689 if (authctxt->methoddata != NULL) 1690 fatal("%s: authctxt->methoddata already set (%p)", 1691 __func__, authctxt->methoddata); 1692 1693 authctxt->methoddata = pctx = jpake_new(); 1694 1695 /* 1696 * Send request immediately, to get the protocol going while 1697 * we do the initial computations. 1698 */ 1699 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1700 packet_put_cstring(authctxt->server_user); 1701 packet_put_cstring(authctxt->service); 1702 packet_put_cstring(authctxt->method->name); 1703 packet_send(); 1704 packet_write_wait(); 1705 1706 jpake_step1(pctx->grp, 1707 &pctx->client_id, &pctx->client_id_len, 1708 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1709 &x1_proof, &x1_proof_len, 1710 &x2_proof, &x2_proof_len); 1711 1712 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1713 1714 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1715 packet_put_string(pctx->client_id, pctx->client_id_len); 1716 packet_put_bignum2(pctx->g_x1); 1717 packet_put_bignum2(pctx->g_x2); 1718 packet_put_string(x1_proof, x1_proof_len); 1719 packet_put_string(x2_proof, x2_proof_len); 1720 packet_send(); 1721 1722 bzero(x1_proof, x1_proof_len); 1723 bzero(x2_proof, x2_proof_len); 1724 xfree(x1_proof); 1725 xfree(x2_proof); 1726 1727 /* Expect step 1 packet from peer */ 1728 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1729 input_userauth_jpake_server_step1); 1730 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1731 &input_userauth_success_unexpected); 1732 1733 return 1; 1734 } 1735 1736 void 1737 userauth_jpake_cleanup(Authctxt *authctxt) 1738 { 1739 debug3("%s: clean up", __func__); 1740 if (authctxt->methoddata != NULL) { 1741 jpake_free(authctxt->methoddata); 1742 authctxt->methoddata = NULL; 1743 } 1744 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1745 } 1746 #endif /* JPAKE */ 1747 1748 /* find auth method */ 1749 1750 /* 1751 * given auth method name, if configurable options permit this method fill 1752 * in auth_ident field and return true, otherwise return false. 1753 */ 1754 static int 1755 authmethod_is_enabled(Authmethod *method) 1756 { 1757 if (method == NULL) 1758 return 0; 1759 /* return false if options indicate this method is disabled */ 1760 if (method->enabled == NULL || *method->enabled == 0) 1761 return 0; 1762 /* return false if batch mode is enabled but method needs interactive mode */ 1763 if (method->batch_flag != NULL && *method->batch_flag != 0) 1764 return 0; 1765 return 1; 1766 } 1767 1768 static Authmethod * 1769 authmethod_lookup(const char *name) 1770 { 1771 Authmethod *method = NULL; 1772 if (name != NULL) 1773 for (method = authmethods; method->name != NULL; method++) 1774 if (strcmp(name, method->name) == 0) 1775 return method; 1776 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1777 return NULL; 1778 } 1779 1780 /* XXX internal state */ 1781 static Authmethod *current = NULL; 1782 static char *supported = NULL; 1783 static char *preferred = NULL; 1784 1785 /* 1786 * Given the authentication method list sent by the server, return the 1787 * next method we should try. If the server initially sends a nil list, 1788 * use a built-in default list. 1789 */ 1790 static Authmethod * 1791 authmethod_get(char *authlist) 1792 { 1793 char *name = NULL; 1794 u_int next; 1795 1796 /* Use a suitable default if we're passed a nil list. */ 1797 if (authlist == NULL || strlen(authlist) == 0) 1798 authlist = options.preferred_authentications; 1799 1800 if (supported == NULL || strcmp(authlist, supported) != 0) { 1801 debug3("start over, passed a different list %s", authlist); 1802 if (supported != NULL) 1803 xfree(supported); 1804 supported = xstrdup(authlist); 1805 preferred = options.preferred_authentications; 1806 debug3("preferred %s", preferred); 1807 current = NULL; 1808 } else if (current != NULL && authmethod_is_enabled(current)) 1809 return current; 1810 1811 for (;;) { 1812 if ((name = match_list(preferred, supported, &next)) == NULL) { 1813 debug("No more authentication methods to try."); 1814 current = NULL; 1815 return NULL; 1816 } 1817 preferred += next; 1818 debug3("authmethod_lookup %s", name); 1819 debug3("remaining preferred: %s", preferred); 1820 if ((current = authmethod_lookup(name)) != NULL && 1821 authmethod_is_enabled(current)) { 1822 debug3("authmethod_is_enabled %s", name); 1823 debug("Next authentication method: %s", name); 1824 return current; 1825 } 1826 } 1827 } 1828 1829 static char * 1830 authmethods_get(void) 1831 { 1832 Authmethod *method = NULL; 1833 Buffer b; 1834 char *list; 1835 1836 buffer_init(&b); 1837 for (method = authmethods; method->name != NULL; method++) { 1838 if (authmethod_is_enabled(method)) { 1839 if (buffer_len(&b) > 0) 1840 buffer_append(&b, ",", 1); 1841 buffer_append(&b, method->name, strlen(method->name)); 1842 } 1843 } 1844 buffer_append(&b, "\0", 1); 1845 list = xstrdup(buffer_ptr(&b)); 1846 buffer_free(&b); 1847 return list; 1848 } 1849 1850