1 /* $OpenBSD: sshconnect2.c,v 1.176 2009/12/06 23:41:15 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 const char *host = options.host_key_alias ? options.host_key_alias : 802 authctxt->host; 803 804 if (attempt++ >= options.number_of_password_prompts) 805 return 0; 806 807 if (attempt != 1) 808 error("Permission denied, please try again."); 809 810 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 811 authctxt->server_user, host); 812 password = read_passphrase(prompt, 0); 813 packet_start(SSH2_MSG_USERAUTH_REQUEST); 814 packet_put_cstring(authctxt->server_user); 815 packet_put_cstring(authctxt->service); 816 packet_put_cstring(authctxt->method->name); 817 packet_put_char(0); 818 packet_put_cstring(password); 819 memset(password, 0, strlen(password)); 820 xfree(password); 821 packet_add_padding(64); 822 packet_send(); 823 824 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 825 &input_userauth_passwd_changereq); 826 827 return 1; 828 } 829 830 /* 831 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 832 */ 833 /* ARGSUSED */ 834 void 835 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 836 { 837 Authctxt *authctxt = ctxt; 838 char *info, *lang, *password = NULL, *retype = NULL; 839 char prompt[150]; 840 const char *host = options.host_key_alias ? options.host_key_alias : 841 authctxt->host; 842 843 debug2("input_userauth_passwd_changereq"); 844 845 if (authctxt == NULL) 846 fatal("input_userauth_passwd_changereq: " 847 "no authentication context"); 848 849 info = packet_get_string(NULL); 850 lang = packet_get_string(NULL); 851 if (strlen(info) > 0) 852 logit("%s", info); 853 xfree(info); 854 xfree(lang); 855 packet_start(SSH2_MSG_USERAUTH_REQUEST); 856 packet_put_cstring(authctxt->server_user); 857 packet_put_cstring(authctxt->service); 858 packet_put_cstring(authctxt->method->name); 859 packet_put_char(1); /* additional info */ 860 snprintf(prompt, sizeof(prompt), 861 "Enter %.30s@%.128s's old password: ", 862 authctxt->server_user, host); 863 password = read_passphrase(prompt, 0); 864 packet_put_cstring(password); 865 memset(password, 0, strlen(password)); 866 xfree(password); 867 password = NULL; 868 while (password == NULL) { 869 snprintf(prompt, sizeof(prompt), 870 "Enter %.30s@%.128s's new password: ", 871 authctxt->server_user, host); 872 password = read_passphrase(prompt, RP_ALLOW_EOF); 873 if (password == NULL) { 874 /* bail out */ 875 return; 876 } 877 snprintf(prompt, sizeof(prompt), 878 "Retype %.30s@%.128s's new password: ", 879 authctxt->server_user, host); 880 retype = read_passphrase(prompt, 0); 881 if (strcmp(password, retype) != 0) { 882 memset(password, 0, strlen(password)); 883 xfree(password); 884 logit("Mismatch; try again, EOF to quit."); 885 password = NULL; 886 } 887 memset(retype, 0, strlen(retype)); 888 xfree(retype); 889 } 890 packet_put_cstring(password); 891 memset(password, 0, strlen(password)); 892 xfree(password); 893 packet_add_padding(64); 894 packet_send(); 895 896 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 897 &input_userauth_passwd_changereq); 898 } 899 900 #ifdef JPAKE 901 static char * 902 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 903 { 904 /* OpenBSD crypt(3) handles all of these */ 905 if (strcmp(crypt_scheme, "crypt") == 0 || 906 strcmp(crypt_scheme, "bcrypt") == 0 || 907 strcmp(crypt_scheme, "md5crypt") == 0 || 908 strcmp(crypt_scheme, "crypt-extended") == 0) 909 return xstrdup(crypt(password, salt)); 910 error("%s: unsupported password encryption scheme \"%.100s\"", 911 __func__, crypt_scheme); 912 return NULL; 913 } 914 915 static BIGNUM * 916 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 917 const char *salt) 918 { 919 char prompt[256], *password, *crypted; 920 u_char *secret; 921 u_int secret_len; 922 BIGNUM *ret; 923 924 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 925 authctxt->server_user, authctxt->host); 926 password = read_passphrase(prompt, 0); 927 928 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 929 logit("Disabling %s authentication", authctxt->method->name); 930 authctxt->method->enabled = NULL; 931 /* Continue with an empty password to fail gracefully */ 932 crypted = xstrdup(""); 933 } 934 935 #ifdef JPAKE_DEBUG 936 debug3("%s: salt = %s", __func__, salt); 937 debug3("%s: scheme = %s", __func__, crypt_scheme); 938 debug3("%s: crypted = %s", __func__, crypted); 939 #endif 940 941 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 942 &secret, &secret_len) != 0) 943 fatal("%s: hash_buffer", __func__); 944 945 bzero(password, strlen(password)); 946 bzero(crypted, strlen(crypted)); 947 xfree(password); 948 xfree(crypted); 949 950 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 951 fatal("%s: BN_bin2bn (secret)", __func__); 952 bzero(secret, secret_len); 953 xfree(secret); 954 955 return ret; 956 } 957 958 /* ARGSUSED */ 959 void 960 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 961 { 962 Authctxt *authctxt = ctxt; 963 struct jpake_ctx *pctx = authctxt->methoddata; 964 u_char *x3_proof, *x4_proof, *x2_s_proof; 965 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 966 char *crypt_scheme, *salt; 967 968 /* Disable this message */ 969 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 970 971 if ((pctx->g_x3 = BN_new()) == NULL || 972 (pctx->g_x4 = BN_new()) == NULL) 973 fatal("%s: BN_new", __func__); 974 975 /* Fetch step 1 values */ 976 crypt_scheme = packet_get_string(NULL); 977 salt = packet_get_string(NULL); 978 pctx->server_id = packet_get_string(&pctx->server_id_len); 979 packet_get_bignum2(pctx->g_x3); 980 packet_get_bignum2(pctx->g_x4); 981 x3_proof = packet_get_string(&x3_proof_len); 982 x4_proof = packet_get_string(&x4_proof_len); 983 packet_check_eom(); 984 985 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 986 987 /* Obtain password and derive secret */ 988 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 989 bzero(crypt_scheme, strlen(crypt_scheme)); 990 bzero(salt, strlen(salt)); 991 xfree(crypt_scheme); 992 xfree(salt); 993 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 994 995 /* Calculate step 2 values */ 996 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 997 pctx->g_x3, pctx->g_x4, pctx->x2, 998 pctx->server_id, pctx->server_id_len, 999 pctx->client_id, pctx->client_id_len, 1000 x3_proof, x3_proof_len, 1001 x4_proof, x4_proof_len, 1002 &pctx->a, 1003 &x2_s_proof, &x2_s_proof_len); 1004 1005 bzero(x3_proof, x3_proof_len); 1006 bzero(x4_proof, x4_proof_len); 1007 xfree(x3_proof); 1008 xfree(x4_proof); 1009 1010 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1011 1012 /* Send values for step 2 */ 1013 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1014 packet_put_bignum2(pctx->a); 1015 packet_put_string(x2_s_proof, x2_s_proof_len); 1016 packet_send(); 1017 1018 bzero(x2_s_proof, x2_s_proof_len); 1019 xfree(x2_s_proof); 1020 1021 /* Expect step 2 packet from peer */ 1022 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1023 input_userauth_jpake_server_step2); 1024 } 1025 1026 /* ARGSUSED */ 1027 void 1028 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1029 { 1030 Authctxt *authctxt = ctxt; 1031 struct jpake_ctx *pctx = authctxt->methoddata; 1032 u_char *x4_s_proof; 1033 u_int x4_s_proof_len; 1034 1035 /* Disable this message */ 1036 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1037 1038 if ((pctx->b = BN_new()) == NULL) 1039 fatal("%s: BN_new", __func__); 1040 1041 /* Fetch step 2 values */ 1042 packet_get_bignum2(pctx->b); 1043 x4_s_proof = packet_get_string(&x4_s_proof_len); 1044 packet_check_eom(); 1045 1046 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1047 1048 /* Derive shared key and calculate confirmation hash */ 1049 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1050 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1051 pctx->client_id, pctx->client_id_len, 1052 pctx->server_id, pctx->server_id_len, 1053 session_id2, session_id2_len, 1054 x4_s_proof, x4_s_proof_len, 1055 &pctx->k, 1056 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1057 1058 bzero(x4_s_proof, x4_s_proof_len); 1059 xfree(x4_s_proof); 1060 1061 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1062 1063 /* Send key confirmation proof */ 1064 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1065 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1066 packet_send(); 1067 1068 /* Expect confirmation from peer */ 1069 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1070 input_userauth_jpake_server_confirm); 1071 } 1072 1073 /* ARGSUSED */ 1074 void 1075 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1076 { 1077 Authctxt *authctxt = ctxt; 1078 struct jpake_ctx *pctx = authctxt->methoddata; 1079 1080 /* Disable this message */ 1081 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1082 1083 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1084 packet_check_eom(); 1085 1086 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1087 1088 /* Verify expected confirmation hash */ 1089 if (jpake_check_confirm(pctx->k, 1090 pctx->server_id, pctx->server_id_len, 1091 session_id2, session_id2_len, 1092 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1093 debug("%s: %s success", __func__, authctxt->method->name); 1094 else { 1095 debug("%s: confirmation mismatch", __func__); 1096 /* XXX stash this so if auth succeeds then we can warn/kill */ 1097 } 1098 1099 userauth_jpake_cleanup(authctxt); 1100 } 1101 #endif /* JPAKE */ 1102 1103 static int 1104 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1105 u_char *data, u_int datalen) 1106 { 1107 Key *prv; 1108 int ret; 1109 1110 /* the agent supports this key */ 1111 if (id->ac) 1112 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1113 data, datalen)); 1114 /* 1115 * we have already loaded the private key or 1116 * the private key is stored in external hardware 1117 */ 1118 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1119 return (key_sign(id->key, sigp, lenp, data, datalen)); 1120 /* load the private key from the file */ 1121 if ((prv = load_identity_file(id->filename)) == NULL) 1122 return (-1); 1123 ret = key_sign(prv, sigp, lenp, data, datalen); 1124 key_free(prv); 1125 return (ret); 1126 } 1127 1128 static int 1129 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1130 { 1131 Buffer b; 1132 u_char *blob, *signature; 1133 u_int bloblen, slen; 1134 u_int skip = 0; 1135 int ret = -1; 1136 int have_sig = 1; 1137 1138 debug3("sign_and_send_pubkey"); 1139 1140 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1141 /* we cannot handle this key */ 1142 debug3("sign_and_send_pubkey: cannot handle key"); 1143 return 0; 1144 } 1145 /* data to be signed */ 1146 buffer_init(&b); 1147 if (datafellows & SSH_OLD_SESSIONID) { 1148 buffer_append(&b, session_id2, session_id2_len); 1149 skip = session_id2_len; 1150 } else { 1151 buffer_put_string(&b, session_id2, session_id2_len); 1152 skip = buffer_len(&b); 1153 } 1154 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1155 buffer_put_cstring(&b, authctxt->server_user); 1156 buffer_put_cstring(&b, 1157 datafellows & SSH_BUG_PKSERVICE ? 1158 "ssh-userauth" : 1159 authctxt->service); 1160 if (datafellows & SSH_BUG_PKAUTH) { 1161 buffer_put_char(&b, have_sig); 1162 } else { 1163 buffer_put_cstring(&b, authctxt->method->name); 1164 buffer_put_char(&b, have_sig); 1165 buffer_put_cstring(&b, key_ssh_name(id->key)); 1166 } 1167 buffer_put_string(&b, blob, bloblen); 1168 1169 /* generate signature */ 1170 ret = identity_sign(id, &signature, &slen, 1171 buffer_ptr(&b), buffer_len(&b)); 1172 if (ret == -1) { 1173 xfree(blob); 1174 buffer_free(&b); 1175 return 0; 1176 } 1177 #ifdef DEBUG_PK 1178 buffer_dump(&b); 1179 #endif 1180 if (datafellows & SSH_BUG_PKSERVICE) { 1181 buffer_clear(&b); 1182 buffer_append(&b, session_id2, session_id2_len); 1183 skip = session_id2_len; 1184 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1185 buffer_put_cstring(&b, authctxt->server_user); 1186 buffer_put_cstring(&b, authctxt->service); 1187 buffer_put_cstring(&b, authctxt->method->name); 1188 buffer_put_char(&b, have_sig); 1189 if (!(datafellows & SSH_BUG_PKAUTH)) 1190 buffer_put_cstring(&b, key_ssh_name(id->key)); 1191 buffer_put_string(&b, blob, bloblen); 1192 } 1193 xfree(blob); 1194 1195 /* append signature */ 1196 buffer_put_string(&b, signature, slen); 1197 xfree(signature); 1198 1199 /* skip session id and packet type */ 1200 if (buffer_len(&b) < skip + 1) 1201 fatal("userauth_pubkey: internal error"); 1202 buffer_consume(&b, skip + 1); 1203 1204 /* put remaining data from buffer into packet */ 1205 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1206 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1207 buffer_free(&b); 1208 packet_send(); 1209 1210 return 1; 1211 } 1212 1213 static int 1214 send_pubkey_test(Authctxt *authctxt, Identity *id) 1215 { 1216 u_char *blob; 1217 u_int bloblen, have_sig = 0; 1218 1219 debug3("send_pubkey_test"); 1220 1221 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1222 /* we cannot handle this key */ 1223 debug3("send_pubkey_test: cannot handle key"); 1224 return 0; 1225 } 1226 /* register callback for USERAUTH_PK_OK message */ 1227 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1228 1229 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1230 packet_put_cstring(authctxt->server_user); 1231 packet_put_cstring(authctxt->service); 1232 packet_put_cstring(authctxt->method->name); 1233 packet_put_char(have_sig); 1234 if (!(datafellows & SSH_BUG_PKAUTH)) 1235 packet_put_cstring(key_ssh_name(id->key)); 1236 packet_put_string(blob, bloblen); 1237 xfree(blob); 1238 packet_send(); 1239 return 1; 1240 } 1241 1242 static Key * 1243 load_identity_file(char *filename) 1244 { 1245 Key *private; 1246 char prompt[300], *passphrase; 1247 int perm_ok, quit, i; 1248 struct stat st; 1249 1250 if (stat(filename, &st) < 0) { 1251 debug3("no such identity: %s", filename); 1252 return NULL; 1253 } 1254 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1255 if (!perm_ok) 1256 return NULL; 1257 if (private == NULL) { 1258 if (options.batch_mode) 1259 return NULL; 1260 snprintf(prompt, sizeof prompt, 1261 "Enter passphrase for key '%.100s': ", filename); 1262 for (i = 0; i < options.number_of_password_prompts; i++) { 1263 passphrase = read_passphrase(prompt, 0); 1264 if (strcmp(passphrase, "") != 0) { 1265 private = key_load_private_type(KEY_UNSPEC, 1266 filename, passphrase, NULL, NULL); 1267 quit = 0; 1268 } else { 1269 debug2("no passphrase given, try next key"); 1270 quit = 1; 1271 } 1272 memset(passphrase, 0, strlen(passphrase)); 1273 xfree(passphrase); 1274 if (private != NULL || quit) 1275 break; 1276 debug2("bad passphrase given, try again..."); 1277 } 1278 } 1279 return private; 1280 } 1281 1282 /* 1283 * try keys in the following order: 1284 * 1. agent keys that are found in the config file 1285 * 2. other agent keys 1286 * 3. keys that are only listed in the config file 1287 */ 1288 static void 1289 pubkey_prepare(Authctxt *authctxt) 1290 { 1291 Identity *id; 1292 Idlist agent, files, *preferred; 1293 Key *key; 1294 AuthenticationConnection *ac; 1295 char *comment; 1296 int i, found; 1297 1298 TAILQ_INIT(&agent); /* keys from the agent */ 1299 TAILQ_INIT(&files); /* keys from the config file */ 1300 preferred = &authctxt->keys; 1301 TAILQ_INIT(preferred); /* preferred order of keys */ 1302 1303 /* list of keys stored in the filesystem */ 1304 for (i = 0; i < options.num_identity_files; i++) { 1305 key = options.identity_keys[i]; 1306 if (key && key->type == KEY_RSA1) 1307 continue; 1308 options.identity_keys[i] = NULL; 1309 id = xcalloc(1, sizeof(*id)); 1310 id->key = key; 1311 id->filename = xstrdup(options.identity_files[i]); 1312 TAILQ_INSERT_TAIL(&files, id, next); 1313 } 1314 /* list of keys supported by the agent */ 1315 if ((ac = ssh_get_authentication_connection())) { 1316 for (key = ssh_get_first_identity(ac, &comment, 2); 1317 key != NULL; 1318 key = ssh_get_next_identity(ac, &comment, 2)) { 1319 found = 0; 1320 TAILQ_FOREACH(id, &files, next) { 1321 /* agent keys from the config file are preferred */ 1322 if (key_equal(key, id->key)) { 1323 key_free(key); 1324 xfree(comment); 1325 TAILQ_REMOVE(&files, id, next); 1326 TAILQ_INSERT_TAIL(preferred, id, next); 1327 id->ac = ac; 1328 found = 1; 1329 break; 1330 } 1331 } 1332 if (!found && !options.identities_only) { 1333 id = xcalloc(1, sizeof(*id)); 1334 id->key = key; 1335 id->filename = comment; 1336 id->ac = ac; 1337 TAILQ_INSERT_TAIL(&agent, id, next); 1338 } 1339 } 1340 /* append remaining agent keys */ 1341 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1342 TAILQ_REMOVE(&agent, id, next); 1343 TAILQ_INSERT_TAIL(preferred, id, next); 1344 } 1345 authctxt->agent = ac; 1346 } 1347 /* append remaining keys from the config file */ 1348 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1349 TAILQ_REMOVE(&files, id, next); 1350 TAILQ_INSERT_TAIL(preferred, id, next); 1351 } 1352 TAILQ_FOREACH(id, preferred, next) { 1353 debug2("key: %s (%p)", id->filename, id->key); 1354 } 1355 } 1356 1357 static void 1358 pubkey_cleanup(Authctxt *authctxt) 1359 { 1360 Identity *id; 1361 1362 if (authctxt->agent != NULL) 1363 ssh_close_authentication_connection(authctxt->agent); 1364 for (id = TAILQ_FIRST(&authctxt->keys); id; 1365 id = TAILQ_FIRST(&authctxt->keys)) { 1366 TAILQ_REMOVE(&authctxt->keys, id, next); 1367 if (id->key) 1368 key_free(id->key); 1369 if (id->filename) 1370 xfree(id->filename); 1371 xfree(id); 1372 } 1373 } 1374 1375 int 1376 userauth_pubkey(Authctxt *authctxt) 1377 { 1378 Identity *id; 1379 int sent = 0; 1380 1381 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1382 if (id->tried++) 1383 return (0); 1384 /* move key to the end of the queue */ 1385 TAILQ_REMOVE(&authctxt->keys, id, next); 1386 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1387 /* 1388 * send a test message if we have the public key. for 1389 * encrypted keys we cannot do this and have to load the 1390 * private key instead 1391 */ 1392 if (id->key && id->key->type != KEY_RSA1) { 1393 debug("Offering public key: %s", id->filename); 1394 sent = send_pubkey_test(authctxt, id); 1395 } else if (id->key == NULL) { 1396 debug("Trying private key: %s", id->filename); 1397 id->key = load_identity_file(id->filename); 1398 if (id->key != NULL) { 1399 id->isprivate = 1; 1400 sent = sign_and_send_pubkey(authctxt, id); 1401 key_free(id->key); 1402 id->key = NULL; 1403 } 1404 } 1405 if (sent) 1406 return (sent); 1407 } 1408 return (0); 1409 } 1410 1411 /* 1412 * Send userauth request message specifying keyboard-interactive method. 1413 */ 1414 int 1415 userauth_kbdint(Authctxt *authctxt) 1416 { 1417 static int attempt = 0; 1418 1419 if (attempt++ >= options.number_of_password_prompts) 1420 return 0; 1421 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1422 if (attempt > 1 && !authctxt->info_req_seen) { 1423 debug3("userauth_kbdint: disable: no info_req_seen"); 1424 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1425 return 0; 1426 } 1427 1428 debug2("userauth_kbdint"); 1429 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1430 packet_put_cstring(authctxt->server_user); 1431 packet_put_cstring(authctxt->service); 1432 packet_put_cstring(authctxt->method->name); 1433 packet_put_cstring(""); /* lang */ 1434 packet_put_cstring(options.kbd_interactive_devices ? 1435 options.kbd_interactive_devices : ""); 1436 packet_send(); 1437 1438 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1439 return 1; 1440 } 1441 1442 /* 1443 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1444 */ 1445 void 1446 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1447 { 1448 Authctxt *authctxt = ctxt; 1449 char *name, *inst, *lang, *prompt, *response; 1450 u_int num_prompts, i; 1451 int echo = 0; 1452 1453 debug2("input_userauth_info_req"); 1454 1455 if (authctxt == NULL) 1456 fatal("input_userauth_info_req: no authentication context"); 1457 1458 authctxt->info_req_seen = 1; 1459 1460 name = packet_get_string(NULL); 1461 inst = packet_get_string(NULL); 1462 lang = packet_get_string(NULL); 1463 if (strlen(name) > 0) 1464 logit("%s", name); 1465 if (strlen(inst) > 0) 1466 logit("%s", inst); 1467 xfree(name); 1468 xfree(inst); 1469 xfree(lang); 1470 1471 num_prompts = packet_get_int(); 1472 /* 1473 * Begin to build info response packet based on prompts requested. 1474 * We commit to providing the correct number of responses, so if 1475 * further on we run into a problem that prevents this, we have to 1476 * be sure and clean this up and send a correct error response. 1477 */ 1478 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1479 packet_put_int(num_prompts); 1480 1481 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1482 for (i = 0; i < num_prompts; i++) { 1483 prompt = packet_get_string(NULL); 1484 echo = packet_get_char(); 1485 1486 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1487 1488 packet_put_cstring(response); 1489 memset(response, 0, strlen(response)); 1490 xfree(response); 1491 xfree(prompt); 1492 } 1493 packet_check_eom(); /* done with parsing incoming message. */ 1494 1495 packet_add_padding(64); 1496 packet_send(); 1497 } 1498 1499 static int 1500 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1501 u_char *data, u_int datalen) 1502 { 1503 Buffer b; 1504 struct stat st; 1505 pid_t pid; 1506 int to[2], from[2], status, version = 2; 1507 1508 debug2("ssh_keysign called"); 1509 1510 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1511 error("ssh_keysign: no installed: %s", strerror(errno)); 1512 return -1; 1513 } 1514 if (fflush(stdout) != 0) 1515 error("ssh_keysign: fflush: %s", strerror(errno)); 1516 if (pipe(to) < 0) { 1517 error("ssh_keysign: pipe: %s", strerror(errno)); 1518 return -1; 1519 } 1520 if (pipe(from) < 0) { 1521 error("ssh_keysign: pipe: %s", strerror(errno)); 1522 return -1; 1523 } 1524 if ((pid = fork()) < 0) { 1525 error("ssh_keysign: fork: %s", strerror(errno)); 1526 return -1; 1527 } 1528 if (pid == 0) { 1529 /* keep the socket on exec */ 1530 fcntl(packet_get_connection_in(), F_SETFD, 0); 1531 permanently_drop_suid(getuid()); 1532 close(from[0]); 1533 if (dup2(from[1], STDOUT_FILENO) < 0) 1534 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1535 close(to[1]); 1536 if (dup2(to[0], STDIN_FILENO) < 0) 1537 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1538 close(from[1]); 1539 close(to[0]); 1540 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1541 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1542 strerror(errno)); 1543 } 1544 close(from[1]); 1545 close(to[0]); 1546 1547 buffer_init(&b); 1548 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1549 buffer_put_string(&b, data, datalen); 1550 if (ssh_msg_send(to[1], version, &b) == -1) 1551 fatal("ssh_keysign: couldn't send request"); 1552 1553 if (ssh_msg_recv(from[0], &b) < 0) { 1554 error("ssh_keysign: no reply"); 1555 buffer_free(&b); 1556 return -1; 1557 } 1558 close(from[0]); 1559 close(to[1]); 1560 1561 while (waitpid(pid, &status, 0) < 0) 1562 if (errno != EINTR) 1563 break; 1564 1565 if (buffer_get_char(&b) != version) { 1566 error("ssh_keysign: bad version"); 1567 buffer_free(&b); 1568 return -1; 1569 } 1570 *sigp = buffer_get_string(&b, lenp); 1571 buffer_free(&b); 1572 1573 return 0; 1574 } 1575 1576 int 1577 userauth_hostbased(Authctxt *authctxt) 1578 { 1579 Key *private = NULL; 1580 Sensitive *sensitive = authctxt->sensitive; 1581 Buffer b; 1582 u_char *signature, *blob; 1583 char *chost, *pkalg, *p, myname[NI_MAXHOST]; 1584 const char *service; 1585 u_int blen, slen; 1586 int ok, i, found = 0; 1587 1588 /* check for a useful key */ 1589 for (i = 0; i < sensitive->nkeys; i++) { 1590 private = sensitive->keys[i]; 1591 if (private && private->type != KEY_RSA1) { 1592 found = 1; 1593 /* we take and free the key */ 1594 sensitive->keys[i] = NULL; 1595 break; 1596 } 1597 } 1598 if (!found) { 1599 debug("No more client hostkeys for hostbased authentication."); 1600 return 0; 1601 } 1602 if (key_to_blob(private, &blob, &blen) == 0) { 1603 key_free(private); 1604 return 0; 1605 } 1606 /* figure out a name for the client host */ 1607 p = NULL; 1608 if (packet_connection_is_on_socket()) 1609 p = get_local_name(packet_get_connection_in()); 1610 if (p == NULL) { 1611 if (gethostname(myname, sizeof(myname)) == -1) { 1612 verbose("userauth_hostbased: gethostname: %s", 1613 strerror(errno)); 1614 } else 1615 p = xstrdup(myname); 1616 } 1617 if (p == NULL) { 1618 error("userauth_hostbased: cannot get local ipaddr/name"); 1619 key_free(private); 1620 xfree(blob); 1621 return 0; 1622 } 1623 xasprintf(&chost, "%s.", p); 1624 debug2("userauth_hostbased: chost %s", chost); 1625 xfree(p); 1626 1627 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1628 authctxt->service; 1629 pkalg = xstrdup(key_ssh_name(private)); 1630 buffer_init(&b); 1631 /* construct data */ 1632 buffer_put_string(&b, session_id2, session_id2_len); 1633 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1634 buffer_put_cstring(&b, authctxt->server_user); 1635 buffer_put_cstring(&b, service); 1636 buffer_put_cstring(&b, authctxt->method->name); 1637 buffer_put_cstring(&b, pkalg); 1638 buffer_put_string(&b, blob, blen); 1639 buffer_put_cstring(&b, chost); 1640 buffer_put_cstring(&b, authctxt->local_user); 1641 #ifdef DEBUG_PK 1642 buffer_dump(&b); 1643 #endif 1644 if (sensitive->external_keysign) 1645 ok = ssh_keysign(private, &signature, &slen, 1646 buffer_ptr(&b), buffer_len(&b)); 1647 else 1648 ok = key_sign(private, &signature, &slen, 1649 buffer_ptr(&b), buffer_len(&b)); 1650 key_free(private); 1651 buffer_free(&b); 1652 if (ok != 0) { 1653 error("key_sign failed"); 1654 xfree(chost); 1655 xfree(pkalg); 1656 xfree(blob); 1657 return 0; 1658 } 1659 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1660 packet_put_cstring(authctxt->server_user); 1661 packet_put_cstring(authctxt->service); 1662 packet_put_cstring(authctxt->method->name); 1663 packet_put_cstring(pkalg); 1664 packet_put_string(blob, blen); 1665 packet_put_cstring(chost); 1666 packet_put_cstring(authctxt->local_user); 1667 packet_put_string(signature, slen); 1668 memset(signature, 's', slen); 1669 xfree(signature); 1670 xfree(chost); 1671 xfree(pkalg); 1672 xfree(blob); 1673 1674 packet_send(); 1675 return 1; 1676 } 1677 1678 #ifdef JPAKE 1679 int 1680 userauth_jpake(Authctxt *authctxt) 1681 { 1682 struct jpake_ctx *pctx; 1683 u_char *x1_proof, *x2_proof; 1684 u_int x1_proof_len, x2_proof_len; 1685 static int attempt = 0; /* XXX share with userauth_password's? */ 1686 1687 if (attempt++ >= options.number_of_password_prompts) 1688 return 0; 1689 if (attempt != 1) 1690 error("Permission denied, please try again."); 1691 1692 if (authctxt->methoddata != NULL) 1693 fatal("%s: authctxt->methoddata already set (%p)", 1694 __func__, authctxt->methoddata); 1695 1696 authctxt->methoddata = pctx = jpake_new(); 1697 1698 /* 1699 * Send request immediately, to get the protocol going while 1700 * we do the initial computations. 1701 */ 1702 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1703 packet_put_cstring(authctxt->server_user); 1704 packet_put_cstring(authctxt->service); 1705 packet_put_cstring(authctxt->method->name); 1706 packet_send(); 1707 packet_write_wait(); 1708 1709 jpake_step1(pctx->grp, 1710 &pctx->client_id, &pctx->client_id_len, 1711 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1712 &x1_proof, &x1_proof_len, 1713 &x2_proof, &x2_proof_len); 1714 1715 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1716 1717 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1718 packet_put_string(pctx->client_id, pctx->client_id_len); 1719 packet_put_bignum2(pctx->g_x1); 1720 packet_put_bignum2(pctx->g_x2); 1721 packet_put_string(x1_proof, x1_proof_len); 1722 packet_put_string(x2_proof, x2_proof_len); 1723 packet_send(); 1724 1725 bzero(x1_proof, x1_proof_len); 1726 bzero(x2_proof, x2_proof_len); 1727 xfree(x1_proof); 1728 xfree(x2_proof); 1729 1730 /* Expect step 1 packet from peer */ 1731 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1732 input_userauth_jpake_server_step1); 1733 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1734 &input_userauth_success_unexpected); 1735 1736 return 1; 1737 } 1738 1739 void 1740 userauth_jpake_cleanup(Authctxt *authctxt) 1741 { 1742 debug3("%s: clean up", __func__); 1743 if (authctxt->methoddata != NULL) { 1744 jpake_free(authctxt->methoddata); 1745 authctxt->methoddata = NULL; 1746 } 1747 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1748 } 1749 #endif /* JPAKE */ 1750 1751 /* find auth method */ 1752 1753 /* 1754 * given auth method name, if configurable options permit this method fill 1755 * in auth_ident field and return true, otherwise return false. 1756 */ 1757 static int 1758 authmethod_is_enabled(Authmethod *method) 1759 { 1760 if (method == NULL) 1761 return 0; 1762 /* return false if options indicate this method is disabled */ 1763 if (method->enabled == NULL || *method->enabled == 0) 1764 return 0; 1765 /* return false if batch mode is enabled but method needs interactive mode */ 1766 if (method->batch_flag != NULL && *method->batch_flag != 0) 1767 return 0; 1768 return 1; 1769 } 1770 1771 static Authmethod * 1772 authmethod_lookup(const char *name) 1773 { 1774 Authmethod *method = NULL; 1775 if (name != NULL) 1776 for (method = authmethods; method->name != NULL; method++) 1777 if (strcmp(name, method->name) == 0) 1778 return method; 1779 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1780 return NULL; 1781 } 1782 1783 /* XXX internal state */ 1784 static Authmethod *current = NULL; 1785 static char *supported = NULL; 1786 static char *preferred = NULL; 1787 1788 /* 1789 * Given the authentication method list sent by the server, return the 1790 * next method we should try. If the server initially sends a nil list, 1791 * use a built-in default list. 1792 */ 1793 static Authmethod * 1794 authmethod_get(char *authlist) 1795 { 1796 char *name = NULL; 1797 u_int next; 1798 1799 /* Use a suitable default if we're passed a nil list. */ 1800 if (authlist == NULL || strlen(authlist) == 0) 1801 authlist = options.preferred_authentications; 1802 1803 if (supported == NULL || strcmp(authlist, supported) != 0) { 1804 debug3("start over, passed a different list %s", authlist); 1805 if (supported != NULL) 1806 xfree(supported); 1807 supported = xstrdup(authlist); 1808 preferred = options.preferred_authentications; 1809 debug3("preferred %s", preferred); 1810 current = NULL; 1811 } else if (current != NULL && authmethod_is_enabled(current)) 1812 return current; 1813 1814 for (;;) { 1815 if ((name = match_list(preferred, supported, &next)) == NULL) { 1816 debug("No more authentication methods to try."); 1817 current = NULL; 1818 return NULL; 1819 } 1820 preferred += next; 1821 debug3("authmethod_lookup %s", name); 1822 debug3("remaining preferred: %s", preferred); 1823 if ((current = authmethod_lookup(name)) != NULL && 1824 authmethod_is_enabled(current)) { 1825 debug3("authmethod_is_enabled %s", name); 1826 debug("Next authentication method: %s", name); 1827 return current; 1828 } 1829 } 1830 } 1831 1832 static char * 1833 authmethods_get(void) 1834 { 1835 Authmethod *method = NULL; 1836 Buffer b; 1837 char *list; 1838 1839 buffer_init(&b); 1840 for (method = authmethods; method->name != NULL; method++) { 1841 if (authmethod_is_enabled(method)) { 1842 if (buffer_len(&b) > 0) 1843 buffer_append(&b, ",", 1); 1844 buffer_append(&b, method->name, strlen(method->name)); 1845 } 1846 } 1847 buffer_append(&b, "\0", 1); 1848 list = xstrdup(buffer_ptr(&b)); 1849 buffer_free(&b); 1850 return list; 1851 } 1852 1853