sshconnect2.c revision 264377
1/* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */ 2/* $FreeBSD: stable/10/crypto/openssh/sshconnect2.c 264377 2014-04-12 20:22:59Z des $ */ 3/* 4 * Copyright (c) 2000 Markus Friedl. All rights reserved. 5 * Copyright (c) 2008 Damien Miller. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28#include "includes.h" 29 30#include <sys/types.h> 31#include <sys/socket.h> 32#include <sys/wait.h> 33#include <sys/stat.h> 34 35#include <errno.h> 36#include <fcntl.h> 37#include <netdb.h> 38#include <pwd.h> 39#include <signal.h> 40#include <stdarg.h> 41#include <stdio.h> 42#include <string.h> 43#include <unistd.h> 44#if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 45#include <vis.h> 46#endif 47 48#include "openbsd-compat/sys-queue.h" 49 50#include "xmalloc.h" 51#include "ssh.h" 52#include "ssh2.h" 53#include "buffer.h" 54#include "packet.h" 55#include "compat.h" 56#include "cipher.h" 57#include "key.h" 58#include "kex.h" 59#include "myproposal.h" 60#include "sshconnect.h" 61#include "authfile.h" 62#include "dh.h" 63#include "authfd.h" 64#include "log.h" 65#include "readconf.h" 66#include "misc.h" 67#include "match.h" 68#include "dispatch.h" 69#include "canohost.h" 70#include "msg.h" 71#include "pathnames.h" 72#include "uidswap.h" 73#include "hostfile.h" 74 75#ifdef GSSAPI 76#include "ssh-gss.h" 77#endif 78 79/* import */ 80extern char *client_version_string; 81extern char *server_version_string; 82extern Options options; 83#ifdef NONE_CIPHER_ENABLED 84extern Kex *xxx_kex; 85 86/* 87 * tty_flag is set in ssh.c so we can use it here. If set then prevent 88 * the switch to the null cipher. 89 */ 90 91extern int tty_flag; 92#endif 93 94/* 95 * SSH2 key exchange 96 */ 97 98u_char *session_id2 = NULL; 99u_int session_id2_len = 0; 100 101char *xxx_host; 102struct sockaddr *xxx_hostaddr; 103 104Kex *xxx_kex = NULL; 105 106static int 107verify_host_key_callback(Key *hostkey) 108{ 109 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 110 fatal("Host key verification failed."); 111 return 0; 112} 113 114static char * 115order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 116{ 117 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 118 size_t maxlen; 119 struct hostkeys *hostkeys; 120 int ktype; 121 u_int i; 122 123 /* Find all hostkeys for this hostname */ 124 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 125 hostkeys = init_hostkeys(); 126 for (i = 0; i < options.num_user_hostfiles; i++) 127 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 128 for (i = 0; i < options.num_system_hostfiles; i++) 129 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 130 131 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 132 maxlen = strlen(avail) + 1; 133 first = xmalloc(maxlen); 134 last = xmalloc(maxlen); 135 *first = *last = '\0'; 136 137#define ALG_APPEND(to, from) \ 138 do { \ 139 if (*to != '\0') \ 140 strlcat(to, ",", maxlen); \ 141 strlcat(to, from, maxlen); \ 142 } while (0) 143 144 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 145 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 146 fatal("%s: unknown alg %s", __func__, alg); 147 if (lookup_key_in_hostkeys_by_type(hostkeys, 148 key_type_plain(ktype), NULL)) 149 ALG_APPEND(first, alg); 150 else 151 ALG_APPEND(last, alg); 152 } 153#undef ALG_APPEND 154 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 155 if (*first != '\0') 156 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 157 158 free(first); 159 free(last); 160 free(hostname); 161 free(oavail); 162 free_hostkeys(hostkeys); 163 164 return ret; 165} 166 167void 168ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 169{ 170 Kex *kex; 171 172 xxx_host = host; 173 xxx_hostaddr = hostaddr; 174 175 if (options.ciphers == (char *)-1) { 176 logit("No valid ciphers for protocol version 2 given, using defaults."); 177 options.ciphers = NULL; 178 } 179 if (options.ciphers != NULL) { 180 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 181 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 182 } 183 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 184 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 185 myproposal[PROPOSAL_ENC_ALGS_STOC] = 186 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 187 if (options.compression) { 188 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 189 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 190 } else { 191 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 192 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 193 } 194 if (options.macs != NULL) { 195 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 196 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 197 } 198 if (options.hostkeyalgorithms != NULL) 199 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 200 compat_pkalg_proposal(options.hostkeyalgorithms); 201 else { 202 /* Prefer algorithms that we already have keys for */ 203 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 204 compat_pkalg_proposal( 205 order_hostkeyalgs(host, hostaddr, port)); 206 } 207 if (options.kex_algorithms != NULL) 208 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 209 210 if (options.rekey_limit || options.rekey_interval) 211 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 212 (time_t)options.rekey_interval); 213 214 /* start key exchange */ 215 kex = kex_setup(myproposal); 216 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 217 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 218 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 219 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 220 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 221 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 222 kex->client_version_string=client_version_string; 223 kex->server_version_string=server_version_string; 224 kex->verify_host_key=&verify_host_key_callback; 225 226 xxx_kex = kex; 227 228 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 229 230 if (options.use_roaming && !kex->roaming) { 231 debug("Roaming not allowed by server"); 232 options.use_roaming = 0; 233 } 234 235 session_id2 = kex->session_id; 236 session_id2_len = kex->session_id_len; 237 238#ifdef DEBUG_KEXDH 239 /* send 1st encrypted/maced/compressed message */ 240 packet_start(SSH2_MSG_IGNORE); 241 packet_put_cstring("markus"); 242 packet_send(); 243 packet_write_wait(); 244#endif 245} 246 247/* 248 * Authenticate user 249 */ 250 251typedef struct Authctxt Authctxt; 252typedef struct Authmethod Authmethod; 253typedef struct identity Identity; 254typedef struct idlist Idlist; 255 256struct identity { 257 TAILQ_ENTRY(identity) next; 258 AuthenticationConnection *ac; /* set if agent supports key */ 259 Key *key; /* public/private key */ 260 char *filename; /* comment for agent-only keys */ 261 int tried; 262 int isprivate; /* key points to the private key */ 263 int userprovided; 264}; 265TAILQ_HEAD(idlist, identity); 266 267struct Authctxt { 268 const char *server_user; 269 const char *local_user; 270 const char *host; 271 const char *service; 272 Authmethod *method; 273 sig_atomic_t success; 274 char *authlist; 275 /* pubkey */ 276 Idlist keys; 277 AuthenticationConnection *agent; 278 /* hostbased */ 279 Sensitive *sensitive; 280 /* kbd-interactive */ 281 int info_req_seen; 282 /* generic */ 283 void *methoddata; 284}; 285struct Authmethod { 286 char *name; /* string to compare against server's list */ 287 int (*userauth)(Authctxt *authctxt); 288 void (*cleanup)(Authctxt *authctxt); 289 int *enabled; /* flag in option struct that enables method */ 290 int *batch_flag; /* flag in option struct that disables method */ 291}; 292 293void input_userauth_success(int, u_int32_t, void *); 294void input_userauth_success_unexpected(int, u_int32_t, void *); 295void input_userauth_failure(int, u_int32_t, void *); 296void input_userauth_banner(int, u_int32_t, void *); 297void input_userauth_error(int, u_int32_t, void *); 298void input_userauth_info_req(int, u_int32_t, void *); 299void input_userauth_pk_ok(int, u_int32_t, void *); 300void input_userauth_passwd_changereq(int, u_int32_t, void *); 301 302int userauth_none(Authctxt *); 303int userauth_pubkey(Authctxt *); 304int userauth_passwd(Authctxt *); 305int userauth_kbdint(Authctxt *); 306int userauth_hostbased(Authctxt *); 307 308#ifdef GSSAPI 309int userauth_gssapi(Authctxt *authctxt); 310void input_gssapi_response(int type, u_int32_t, void *); 311void input_gssapi_token(int type, u_int32_t, void *); 312void input_gssapi_hash(int type, u_int32_t, void *); 313void input_gssapi_error(int, u_int32_t, void *); 314void input_gssapi_errtok(int, u_int32_t, void *); 315#endif 316 317void userauth(Authctxt *, char *); 318 319static int sign_and_send_pubkey(Authctxt *, Identity *); 320static void pubkey_prepare(Authctxt *); 321static void pubkey_cleanup(Authctxt *); 322static Key *load_identity_file(char *, int); 323 324static Authmethod *authmethod_get(char *authlist); 325static Authmethod *authmethod_lookup(const char *name); 326static char *authmethods_get(void); 327 328Authmethod authmethods[] = { 329#ifdef GSSAPI 330 {"gssapi-with-mic", 331 userauth_gssapi, 332 NULL, 333 &options.gss_authentication, 334 NULL}, 335#endif 336 {"hostbased", 337 userauth_hostbased, 338 NULL, 339 &options.hostbased_authentication, 340 NULL}, 341 {"publickey", 342 userauth_pubkey, 343 NULL, 344 &options.pubkey_authentication, 345 NULL}, 346 {"keyboard-interactive", 347 userauth_kbdint, 348 NULL, 349 &options.kbd_interactive_authentication, 350 &options.batch_mode}, 351 {"password", 352 userauth_passwd, 353 NULL, 354 &options.password_authentication, 355 &options.batch_mode}, 356 {"none", 357 userauth_none, 358 NULL, 359 NULL, 360 NULL}, 361 {NULL, NULL, NULL, NULL, NULL} 362}; 363 364void 365ssh_userauth2(const char *local_user, const char *server_user, char *host, 366 Sensitive *sensitive) 367{ 368 Authctxt authctxt; 369 int type; 370 371 if (options.challenge_response_authentication) 372 options.kbd_interactive_authentication = 1; 373 374 packet_start(SSH2_MSG_SERVICE_REQUEST); 375 packet_put_cstring("ssh-userauth"); 376 packet_send(); 377 debug("SSH2_MSG_SERVICE_REQUEST sent"); 378 packet_write_wait(); 379 type = packet_read(); 380 if (type != SSH2_MSG_SERVICE_ACCEPT) 381 fatal("Server denied authentication request: %d", type); 382 if (packet_remaining() > 0) { 383 char *reply = packet_get_string(NULL); 384 debug2("service_accept: %s", reply); 385 free(reply); 386 } else { 387 debug2("buggy server: service_accept w/o service"); 388 } 389 packet_check_eom(); 390 debug("SSH2_MSG_SERVICE_ACCEPT received"); 391 392 if (options.preferred_authentications == NULL) 393 options.preferred_authentications = authmethods_get(); 394 395 /* setup authentication context */ 396 memset(&authctxt, 0, sizeof(authctxt)); 397 pubkey_prepare(&authctxt); 398 authctxt.server_user = server_user; 399 authctxt.local_user = local_user; 400 authctxt.host = host; 401 authctxt.service = "ssh-connection"; /* service name */ 402 authctxt.success = 0; 403 authctxt.method = authmethod_lookup("none"); 404 authctxt.authlist = NULL; 405 authctxt.methoddata = NULL; 406 authctxt.sensitive = sensitive; 407 authctxt.info_req_seen = 0; 408 if (authctxt.method == NULL) 409 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 410 411 /* initial userauth request */ 412 userauth_none(&authctxt); 413 414 dispatch_init(&input_userauth_error); 415 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 416 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 417 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 418 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 419 420 pubkey_cleanup(&authctxt); 421 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 422 423#ifdef NONE_CIPHER_ENABLED 424 /* 425 * If the user explicitly requests to use the none cipher enable it 426 * post authentication and only if the right conditions are met: both 427 * of the NONE switches must be true and there must be no tty allocated. 428 */ 429 if (options.none_switch == 1 && options.none_enabled == 1) { 430 if (!tty_flag) { 431 debug("Requesting none cipher re-keying..."); 432 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 433 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 434 kex_prop2buf(&xxx_kex->my, myproposal); 435 packet_request_rekeying(); 436 fprintf(stderr, "WARNING: enabled NONE cipher\n"); 437 } else { 438 /* Requested NONE cipher on an interactive session. */ 439 debug("Cannot switch to NONE cipher with tty " 440 "allocated"); 441 fprintf(stderr, "NONE cipher switch disabled given " 442 "a TTY is allocated\n"); 443 } 444 } 445#endif 446 debug("Authentication succeeded (%s).", authctxt.method->name); 447} 448 449void 450userauth(Authctxt *authctxt, char *authlist) 451{ 452 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 453 authctxt->method->cleanup(authctxt); 454 455 free(authctxt->methoddata); 456 authctxt->methoddata = NULL; 457 if (authlist == NULL) { 458 authlist = authctxt->authlist; 459 } else { 460 free(authctxt->authlist); 461 authctxt->authlist = authlist; 462 } 463 for (;;) { 464 Authmethod *method = authmethod_get(authlist); 465 if (method == NULL) 466 fatal("Permission denied (%s).", authlist); 467 authctxt->method = method; 468 469 /* reset the per method handler */ 470 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 471 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 472 473 /* and try new method */ 474 if (method->userauth(authctxt) != 0) { 475 debug2("we sent a %s packet, wait for reply", method->name); 476 break; 477 } else { 478 debug2("we did not send a packet, disable method"); 479 method->enabled = NULL; 480 } 481 } 482} 483 484/* ARGSUSED */ 485void 486input_userauth_error(int type, u_int32_t seq, void *ctxt) 487{ 488 fatal("input_userauth_error: bad message during authentication: " 489 "type %d", type); 490} 491 492/* ARGSUSED */ 493void 494input_userauth_banner(int type, u_int32_t seq, void *ctxt) 495{ 496 char *msg, *raw, *lang; 497 u_int len; 498 499 debug3("input_userauth_banner"); 500 raw = packet_get_string(&len); 501 lang = packet_get_string(NULL); 502 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 503 if (len > 65536) 504 len = 65536; 505 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 506 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 507 fprintf(stderr, "%s", msg); 508 free(msg); 509 } 510 free(raw); 511 free(lang); 512} 513 514/* ARGSUSED */ 515void 516input_userauth_success(int type, u_int32_t seq, void *ctxt) 517{ 518 Authctxt *authctxt = ctxt; 519 520 if (authctxt == NULL) 521 fatal("input_userauth_success: no authentication context"); 522 free(authctxt->authlist); 523 authctxt->authlist = NULL; 524 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 525 authctxt->method->cleanup(authctxt); 526 free(authctxt->methoddata); 527 authctxt->methoddata = NULL; 528 authctxt->success = 1; /* break out */ 529} 530 531void 532input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 533{ 534 Authctxt *authctxt = ctxt; 535 536 if (authctxt == NULL) 537 fatal("%s: no authentication context", __func__); 538 539 fatal("Unexpected authentication success during %s.", 540 authctxt->method->name); 541} 542 543/* ARGSUSED */ 544void 545input_userauth_failure(int type, u_int32_t seq, void *ctxt) 546{ 547 Authctxt *authctxt = ctxt; 548 char *authlist = NULL; 549 int partial; 550 551 if (authctxt == NULL) 552 fatal("input_userauth_failure: no authentication context"); 553 554 authlist = packet_get_string(NULL); 555 partial = packet_get_char(); 556 packet_check_eom(); 557 558 if (partial != 0) { 559 logit("Authenticated with partial success."); 560 /* reset state */ 561 pubkey_cleanup(authctxt); 562 pubkey_prepare(authctxt); 563 } 564 debug("Authentications that can continue: %s", authlist); 565 566 userauth(authctxt, authlist); 567} 568 569/* ARGSUSED */ 570void 571input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 572{ 573 Authctxt *authctxt = ctxt; 574 Key *key = NULL; 575 Identity *id = NULL; 576 Buffer b; 577 int pktype, sent = 0; 578 u_int alen, blen; 579 char *pkalg, *fp; 580 u_char *pkblob; 581 582 if (authctxt == NULL) 583 fatal("input_userauth_pk_ok: no authentication context"); 584 if (datafellows & SSH_BUG_PKOK) { 585 /* this is similar to SSH_BUG_PKAUTH */ 586 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 587 pkblob = packet_get_string(&blen); 588 buffer_init(&b); 589 buffer_append(&b, pkblob, blen); 590 pkalg = buffer_get_string(&b, &alen); 591 buffer_free(&b); 592 } else { 593 pkalg = packet_get_string(&alen); 594 pkblob = packet_get_string(&blen); 595 } 596 packet_check_eom(); 597 598 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 599 600 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 601 debug("unknown pkalg %s", pkalg); 602 goto done; 603 } 604 if ((key = key_from_blob(pkblob, blen)) == NULL) { 605 debug("no key from blob. pkalg %s", pkalg); 606 goto done; 607 } 608 if (key->type != pktype) { 609 error("input_userauth_pk_ok: type mismatch " 610 "for decoded key (received %d, expected %d)", 611 key->type, pktype); 612 goto done; 613 } 614 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 615 debug2("input_userauth_pk_ok: fp %s", fp); 616 free(fp); 617 618 /* 619 * search keys in the reverse order, because last candidate has been 620 * moved to the end of the queue. this also avoids confusion by 621 * duplicate keys 622 */ 623 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 624 if (key_equal(key, id->key)) { 625 sent = sign_and_send_pubkey(authctxt, id); 626 break; 627 } 628 } 629done: 630 if (key != NULL) 631 key_free(key); 632 free(pkalg); 633 free(pkblob); 634 635 /* try another method if we did not send a packet */ 636 if (sent == 0) 637 userauth(authctxt, NULL); 638} 639 640#ifdef GSSAPI 641int 642userauth_gssapi(Authctxt *authctxt) 643{ 644 Gssctxt *gssctxt = NULL; 645 static gss_OID_set gss_supported = NULL; 646 static u_int mech = 0; 647 OM_uint32 min; 648 int ok = 0; 649 650 /* Try one GSSAPI method at a time, rather than sending them all at 651 * once. */ 652 653 if (gss_supported == NULL) 654 gss_indicate_mechs(&min, &gss_supported); 655 656 /* Check to see if the mechanism is usable before we offer it */ 657 while (mech < gss_supported->count && !ok) { 658 /* My DER encoding requires length<128 */ 659 if (gss_supported->elements[mech].length < 128 && 660 ssh_gssapi_check_mechanism(&gssctxt, 661 &gss_supported->elements[mech], authctxt->host)) { 662 ok = 1; /* Mechanism works */ 663 } else { 664 mech++; 665 } 666 } 667 668 if (!ok) 669 return 0; 670 671 authctxt->methoddata=(void *)gssctxt; 672 673 packet_start(SSH2_MSG_USERAUTH_REQUEST); 674 packet_put_cstring(authctxt->server_user); 675 packet_put_cstring(authctxt->service); 676 packet_put_cstring(authctxt->method->name); 677 678 packet_put_int(1); 679 680 packet_put_int((gss_supported->elements[mech].length) + 2); 681 packet_put_char(SSH_GSS_OIDTYPE); 682 packet_put_char(gss_supported->elements[mech].length); 683 packet_put_raw(gss_supported->elements[mech].elements, 684 gss_supported->elements[mech].length); 685 686 packet_send(); 687 688 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 689 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 690 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 691 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 692 693 mech++; /* Move along to next candidate */ 694 695 return 1; 696} 697 698static OM_uint32 699process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 700{ 701 Authctxt *authctxt = ctxt; 702 Gssctxt *gssctxt = authctxt->methoddata; 703 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 704 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 705 gss_buffer_desc gssbuf; 706 OM_uint32 status, ms, flags; 707 Buffer b; 708 709 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 710 recv_tok, &send_tok, &flags); 711 712 if (send_tok.length > 0) { 713 if (GSS_ERROR(status)) 714 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 715 else 716 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 717 718 packet_put_string(send_tok.value, send_tok.length); 719 packet_send(); 720 gss_release_buffer(&ms, &send_tok); 721 } 722 723 if (status == GSS_S_COMPLETE) { 724 /* send either complete or MIC, depending on mechanism */ 725 if (!(flags & GSS_C_INTEG_FLAG)) { 726 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 727 packet_send(); 728 } else { 729 ssh_gssapi_buildmic(&b, authctxt->server_user, 730 authctxt->service, "gssapi-with-mic"); 731 732 gssbuf.value = buffer_ptr(&b); 733 gssbuf.length = buffer_len(&b); 734 735 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 736 737 if (!GSS_ERROR(status)) { 738 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 739 packet_put_string(mic.value, mic.length); 740 741 packet_send(); 742 } 743 744 buffer_free(&b); 745 gss_release_buffer(&ms, &mic); 746 } 747 } 748 749 return status; 750} 751 752/* ARGSUSED */ 753void 754input_gssapi_response(int type, u_int32_t plen, void *ctxt) 755{ 756 Authctxt *authctxt = ctxt; 757 Gssctxt *gssctxt; 758 int oidlen; 759 char *oidv; 760 761 if (authctxt == NULL) 762 fatal("input_gssapi_response: no authentication context"); 763 gssctxt = authctxt->methoddata; 764 765 /* Setup our OID */ 766 oidv = packet_get_string(&oidlen); 767 768 if (oidlen <= 2 || 769 oidv[0] != SSH_GSS_OIDTYPE || 770 oidv[1] != oidlen - 2) { 771 free(oidv); 772 debug("Badly encoded mechanism OID received"); 773 userauth(authctxt, NULL); 774 return; 775 } 776 777 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 778 fatal("Server returned different OID than expected"); 779 780 packet_check_eom(); 781 782 free(oidv); 783 784 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 785 /* Start again with next method on list */ 786 debug("Trying to start again"); 787 userauth(authctxt, NULL); 788 return; 789 } 790} 791 792/* ARGSUSED */ 793void 794input_gssapi_token(int type, u_int32_t plen, void *ctxt) 795{ 796 Authctxt *authctxt = ctxt; 797 gss_buffer_desc recv_tok; 798 OM_uint32 status; 799 u_int slen; 800 801 if (authctxt == NULL) 802 fatal("input_gssapi_response: no authentication context"); 803 804 recv_tok.value = packet_get_string(&slen); 805 recv_tok.length = slen; /* safe typecast */ 806 807 packet_check_eom(); 808 809 status = process_gssapi_token(ctxt, &recv_tok); 810 811 free(recv_tok.value); 812 813 if (GSS_ERROR(status)) { 814 /* Start again with the next method in the list */ 815 userauth(authctxt, NULL); 816 return; 817 } 818} 819 820/* ARGSUSED */ 821void 822input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 823{ 824 Authctxt *authctxt = ctxt; 825 Gssctxt *gssctxt; 826 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 827 gss_buffer_desc recv_tok; 828 OM_uint32 ms; 829 u_int len; 830 831 if (authctxt == NULL) 832 fatal("input_gssapi_response: no authentication context"); 833 gssctxt = authctxt->methoddata; 834 835 recv_tok.value = packet_get_string(&len); 836 recv_tok.length = len; 837 838 packet_check_eom(); 839 840 /* Stick it into GSSAPI and see what it says */ 841 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 842 &recv_tok, &send_tok, NULL); 843 844 free(recv_tok.value); 845 gss_release_buffer(&ms, &send_tok); 846 847 /* Server will be returning a failed packet after this one */ 848} 849 850/* ARGSUSED */ 851void 852input_gssapi_error(int type, u_int32_t plen, void *ctxt) 853{ 854 char *msg; 855 char *lang; 856 857 /* maj */(void)packet_get_int(); 858 /* min */(void)packet_get_int(); 859 msg=packet_get_string(NULL); 860 lang=packet_get_string(NULL); 861 862 packet_check_eom(); 863 864 debug("Server GSSAPI Error:\n%s", msg); 865 free(msg); 866 free(lang); 867} 868#endif /* GSSAPI */ 869 870int 871userauth_none(Authctxt *authctxt) 872{ 873 /* initial userauth request */ 874 packet_start(SSH2_MSG_USERAUTH_REQUEST); 875 packet_put_cstring(authctxt->server_user); 876 packet_put_cstring(authctxt->service); 877 packet_put_cstring(authctxt->method->name); 878 packet_send(); 879 return 1; 880} 881 882int 883userauth_passwd(Authctxt *authctxt) 884{ 885 static int attempt = 0; 886 char prompt[150]; 887 char *password; 888 const char *host = options.host_key_alias ? options.host_key_alias : 889 authctxt->host; 890 891 if (attempt++ >= options.number_of_password_prompts) 892 return 0; 893 894 if (attempt != 1) 895 error("Permission denied, please try again."); 896 897 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 898 authctxt->server_user, host); 899 password = read_passphrase(prompt, 0); 900 packet_start(SSH2_MSG_USERAUTH_REQUEST); 901 packet_put_cstring(authctxt->server_user); 902 packet_put_cstring(authctxt->service); 903 packet_put_cstring(authctxt->method->name); 904 packet_put_char(0); 905 packet_put_cstring(password); 906 explicit_bzero(password, strlen(password)); 907 free(password); 908 packet_add_padding(64); 909 packet_send(); 910 911 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 912 &input_userauth_passwd_changereq); 913 914 return 1; 915} 916 917/* 918 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 919 */ 920/* ARGSUSED */ 921void 922input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 923{ 924 Authctxt *authctxt = ctxt; 925 char *info, *lang, *password = NULL, *retype = NULL; 926 char prompt[150]; 927 const char *host = options.host_key_alias ? options.host_key_alias : 928 authctxt->host; 929 930 debug2("input_userauth_passwd_changereq"); 931 932 if (authctxt == NULL) 933 fatal("input_userauth_passwd_changereq: " 934 "no authentication context"); 935 936 info = packet_get_string(NULL); 937 lang = packet_get_string(NULL); 938 if (strlen(info) > 0) 939 logit("%s", info); 940 free(info); 941 free(lang); 942 packet_start(SSH2_MSG_USERAUTH_REQUEST); 943 packet_put_cstring(authctxt->server_user); 944 packet_put_cstring(authctxt->service); 945 packet_put_cstring(authctxt->method->name); 946 packet_put_char(1); /* additional info */ 947 snprintf(prompt, sizeof(prompt), 948 "Enter %.30s@%.128s's old password: ", 949 authctxt->server_user, host); 950 password = read_passphrase(prompt, 0); 951 packet_put_cstring(password); 952 explicit_bzero(password, strlen(password)); 953 free(password); 954 password = NULL; 955 while (password == NULL) { 956 snprintf(prompt, sizeof(prompt), 957 "Enter %.30s@%.128s's new password: ", 958 authctxt->server_user, host); 959 password = read_passphrase(prompt, RP_ALLOW_EOF); 960 if (password == NULL) { 961 /* bail out */ 962 return; 963 } 964 snprintf(prompt, sizeof(prompt), 965 "Retype %.30s@%.128s's new password: ", 966 authctxt->server_user, host); 967 retype = read_passphrase(prompt, 0); 968 if (strcmp(password, retype) != 0) { 969 explicit_bzero(password, strlen(password)); 970 free(password); 971 logit("Mismatch; try again, EOF to quit."); 972 password = NULL; 973 } 974 explicit_bzero(retype, strlen(retype)); 975 free(retype); 976 } 977 packet_put_cstring(password); 978 explicit_bzero(password, strlen(password)); 979 free(password); 980 packet_add_padding(64); 981 packet_send(); 982 983 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 984 &input_userauth_passwd_changereq); 985} 986 987static int 988identity_sign(Identity *id, u_char **sigp, u_int *lenp, 989 u_char *data, u_int datalen) 990{ 991 Key *prv; 992 int ret; 993 994 /* the agent supports this key */ 995 if (id->ac) 996 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 997 data, datalen)); 998 /* 999 * we have already loaded the private key or 1000 * the private key is stored in external hardware 1001 */ 1002 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1003 return (key_sign(id->key, sigp, lenp, data, datalen)); 1004 /* load the private key from the file */ 1005 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 1006 return (-1); 1007 ret = key_sign(prv, sigp, lenp, data, datalen); 1008 key_free(prv); 1009 return (ret); 1010} 1011 1012static int 1013sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1014{ 1015 Buffer b; 1016 u_char *blob, *signature; 1017 u_int bloblen, slen; 1018 u_int skip = 0; 1019 int ret = -1; 1020 int have_sig = 1; 1021 char *fp; 1022 1023 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1024 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1025 free(fp); 1026 1027 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1028 /* we cannot handle this key */ 1029 debug3("sign_and_send_pubkey: cannot handle key"); 1030 return 0; 1031 } 1032 /* data to be signed */ 1033 buffer_init(&b); 1034 if (datafellows & SSH_OLD_SESSIONID) { 1035 buffer_append(&b, session_id2, session_id2_len); 1036 skip = session_id2_len; 1037 } else { 1038 buffer_put_string(&b, session_id2, session_id2_len); 1039 skip = buffer_len(&b); 1040 } 1041 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1042 buffer_put_cstring(&b, authctxt->server_user); 1043 buffer_put_cstring(&b, 1044 datafellows & SSH_BUG_PKSERVICE ? 1045 "ssh-userauth" : 1046 authctxt->service); 1047 if (datafellows & SSH_BUG_PKAUTH) { 1048 buffer_put_char(&b, have_sig); 1049 } else { 1050 buffer_put_cstring(&b, authctxt->method->name); 1051 buffer_put_char(&b, have_sig); 1052 buffer_put_cstring(&b, key_ssh_name(id->key)); 1053 } 1054 buffer_put_string(&b, blob, bloblen); 1055 1056 /* generate signature */ 1057 ret = identity_sign(id, &signature, &slen, 1058 buffer_ptr(&b), buffer_len(&b)); 1059 if (ret == -1) { 1060 free(blob); 1061 buffer_free(&b); 1062 return 0; 1063 } 1064#ifdef DEBUG_PK 1065 buffer_dump(&b); 1066#endif 1067 if (datafellows & SSH_BUG_PKSERVICE) { 1068 buffer_clear(&b); 1069 buffer_append(&b, session_id2, session_id2_len); 1070 skip = session_id2_len; 1071 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1072 buffer_put_cstring(&b, authctxt->server_user); 1073 buffer_put_cstring(&b, authctxt->service); 1074 buffer_put_cstring(&b, authctxt->method->name); 1075 buffer_put_char(&b, have_sig); 1076 if (!(datafellows & SSH_BUG_PKAUTH)) 1077 buffer_put_cstring(&b, key_ssh_name(id->key)); 1078 buffer_put_string(&b, blob, bloblen); 1079 } 1080 free(blob); 1081 1082 /* append signature */ 1083 buffer_put_string(&b, signature, slen); 1084 free(signature); 1085 1086 /* skip session id and packet type */ 1087 if (buffer_len(&b) < skip + 1) 1088 fatal("userauth_pubkey: internal error"); 1089 buffer_consume(&b, skip + 1); 1090 1091 /* put remaining data from buffer into packet */ 1092 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1093 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1094 buffer_free(&b); 1095 packet_send(); 1096 1097 return 1; 1098} 1099 1100static int 1101send_pubkey_test(Authctxt *authctxt, Identity *id) 1102{ 1103 u_char *blob; 1104 u_int bloblen, have_sig = 0; 1105 1106 debug3("send_pubkey_test"); 1107 1108 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1109 /* we cannot handle this key */ 1110 debug3("send_pubkey_test: cannot handle key"); 1111 return 0; 1112 } 1113 /* register callback for USERAUTH_PK_OK message */ 1114 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1115 1116 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1117 packet_put_cstring(authctxt->server_user); 1118 packet_put_cstring(authctxt->service); 1119 packet_put_cstring(authctxt->method->name); 1120 packet_put_char(have_sig); 1121 if (!(datafellows & SSH_BUG_PKAUTH)) 1122 packet_put_cstring(key_ssh_name(id->key)); 1123 packet_put_string(blob, bloblen); 1124 free(blob); 1125 packet_send(); 1126 return 1; 1127} 1128 1129static Key * 1130load_identity_file(char *filename, int userprovided) 1131{ 1132 Key *private; 1133 char prompt[300], *passphrase; 1134 int perm_ok = 0, quit, i; 1135 struct stat st; 1136 1137 if (stat(filename, &st) < 0) { 1138 (userprovided ? logit : debug3)("no such identity: %s: %s", 1139 filename, strerror(errno)); 1140 return NULL; 1141 } 1142 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1143 if (!perm_ok) { 1144 if (private != NULL) 1145 key_free(private); 1146 return NULL; 1147 } 1148 if (private == NULL) { 1149 if (options.batch_mode) 1150 return NULL; 1151 snprintf(prompt, sizeof prompt, 1152 "Enter passphrase for key '%.100s': ", filename); 1153 for (i = 0; i < options.number_of_password_prompts; i++) { 1154 passphrase = read_passphrase(prompt, 0); 1155 if (strcmp(passphrase, "") != 0) { 1156 private = key_load_private_type(KEY_UNSPEC, 1157 filename, passphrase, NULL, NULL); 1158 quit = 0; 1159 } else { 1160 debug2("no passphrase given, try next key"); 1161 quit = 1; 1162 } 1163 explicit_bzero(passphrase, strlen(passphrase)); 1164 free(passphrase); 1165 if (private != NULL || quit) 1166 break; 1167 debug2("bad passphrase given, try again..."); 1168 } 1169 } 1170 return private; 1171} 1172 1173/* 1174 * try keys in the following order: 1175 * 1. agent keys that are found in the config file 1176 * 2. other agent keys 1177 * 3. keys that are only listed in the config file 1178 */ 1179static void 1180pubkey_prepare(Authctxt *authctxt) 1181{ 1182 Identity *id, *id2, *tmp; 1183 Idlist agent, files, *preferred; 1184 Key *key; 1185 AuthenticationConnection *ac; 1186 char *comment; 1187 int i, found; 1188 1189 TAILQ_INIT(&agent); /* keys from the agent */ 1190 TAILQ_INIT(&files); /* keys from the config file */ 1191 preferred = &authctxt->keys; 1192 TAILQ_INIT(preferred); /* preferred order of keys */ 1193 1194 /* list of keys stored in the filesystem and PKCS#11 */ 1195 for (i = 0; i < options.num_identity_files; i++) { 1196 key = options.identity_keys[i]; 1197 if (key && key->type == KEY_RSA1) 1198 continue; 1199 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1200 continue; 1201 options.identity_keys[i] = NULL; 1202 id = xcalloc(1, sizeof(*id)); 1203 id->key = key; 1204 id->filename = xstrdup(options.identity_files[i]); 1205 id->userprovided = options.identity_file_userprovided[i]; 1206 TAILQ_INSERT_TAIL(&files, id, next); 1207 } 1208 /* Prefer PKCS11 keys that are explicitly listed */ 1209 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1210 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0) 1211 continue; 1212 found = 0; 1213 TAILQ_FOREACH(id2, &files, next) { 1214 if (id2->key == NULL || 1215 (id2->key->flags & KEY_FLAG_EXT) != 0) 1216 continue; 1217 if (key_equal(id->key, id2->key)) { 1218 TAILQ_REMOVE(&files, id, next); 1219 TAILQ_INSERT_TAIL(preferred, id, next); 1220 found = 1; 1221 break; 1222 } 1223 } 1224 /* If IdentitiesOnly set and key not found then don't use it */ 1225 if (!found && options.identities_only) { 1226 TAILQ_REMOVE(&files, id, next); 1227 explicit_bzero(id, sizeof(*id)); 1228 free(id); 1229 } 1230 } 1231 /* list of keys supported by the agent */ 1232 if ((ac = ssh_get_authentication_connection())) { 1233 for (key = ssh_get_first_identity(ac, &comment, 2); 1234 key != NULL; 1235 key = ssh_get_next_identity(ac, &comment, 2)) { 1236 found = 0; 1237 TAILQ_FOREACH(id, &files, next) { 1238 /* agent keys from the config file are preferred */ 1239 if (key_equal(key, id->key)) { 1240 key_free(key); 1241 free(comment); 1242 TAILQ_REMOVE(&files, id, next); 1243 TAILQ_INSERT_TAIL(preferred, id, next); 1244 id->ac = ac; 1245 found = 1; 1246 break; 1247 } 1248 } 1249 if (!found && !options.identities_only) { 1250 id = xcalloc(1, sizeof(*id)); 1251 id->key = key; 1252 id->filename = comment; 1253 id->ac = ac; 1254 TAILQ_INSERT_TAIL(&agent, id, next); 1255 } 1256 } 1257 /* append remaining agent keys */ 1258 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1259 TAILQ_REMOVE(&agent, id, next); 1260 TAILQ_INSERT_TAIL(preferred, id, next); 1261 } 1262 authctxt->agent = ac; 1263 } 1264 /* append remaining keys from the config file */ 1265 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1266 TAILQ_REMOVE(&files, id, next); 1267 TAILQ_INSERT_TAIL(preferred, id, next); 1268 } 1269 TAILQ_FOREACH(id, preferred, next) { 1270 debug2("key: %s (%p),%s", id->filename, id->key, 1271 id->userprovided ? " explicit" : ""); 1272 } 1273} 1274 1275static void 1276pubkey_cleanup(Authctxt *authctxt) 1277{ 1278 Identity *id; 1279 1280 if (authctxt->agent != NULL) 1281 ssh_close_authentication_connection(authctxt->agent); 1282 for (id = TAILQ_FIRST(&authctxt->keys); id; 1283 id = TAILQ_FIRST(&authctxt->keys)) { 1284 TAILQ_REMOVE(&authctxt->keys, id, next); 1285 if (id->key) 1286 key_free(id->key); 1287 free(id->filename); 1288 free(id); 1289 } 1290} 1291 1292int 1293userauth_pubkey(Authctxt *authctxt) 1294{ 1295 Identity *id; 1296 int sent = 0; 1297 1298 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1299 if (id->tried++) 1300 return (0); 1301 /* move key to the end of the queue */ 1302 TAILQ_REMOVE(&authctxt->keys, id, next); 1303 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1304 /* 1305 * send a test message if we have the public key. for 1306 * encrypted keys we cannot do this and have to load the 1307 * private key instead 1308 */ 1309 if (id->key != NULL) { 1310 if (key_type_plain(id->key->type) == KEY_RSA && 1311 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1312 debug("Skipped %s key %s for RSA/MD5 server", 1313 key_type(id->key), id->filename); 1314 } else if (id->key->type != KEY_RSA1) { 1315 debug("Offering %s public key: %s", 1316 key_type(id->key), id->filename); 1317 sent = send_pubkey_test(authctxt, id); 1318 } 1319 } else { 1320 debug("Trying private key: %s", id->filename); 1321 id->key = load_identity_file(id->filename, 1322 id->userprovided); 1323 if (id->key != NULL) { 1324 id->isprivate = 1; 1325 if (key_type_plain(id->key->type) == KEY_RSA && 1326 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1327 debug("Skipped %s key %s for RSA/MD5 " 1328 "server", key_type(id->key), 1329 id->filename); 1330 } else { 1331 sent = sign_and_send_pubkey( 1332 authctxt, id); 1333 } 1334 key_free(id->key); 1335 id->key = NULL; 1336 } 1337 } 1338 if (sent) 1339 return (sent); 1340 } 1341 return (0); 1342} 1343 1344/* 1345 * Send userauth request message specifying keyboard-interactive method. 1346 */ 1347int 1348userauth_kbdint(Authctxt *authctxt) 1349{ 1350 static int attempt = 0; 1351 1352 if (attempt++ >= options.number_of_password_prompts) 1353 return 0; 1354 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1355 if (attempt > 1 && !authctxt->info_req_seen) { 1356 debug3("userauth_kbdint: disable: no info_req_seen"); 1357 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1358 return 0; 1359 } 1360 1361 debug2("userauth_kbdint"); 1362 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1363 packet_put_cstring(authctxt->server_user); 1364 packet_put_cstring(authctxt->service); 1365 packet_put_cstring(authctxt->method->name); 1366 packet_put_cstring(""); /* lang */ 1367 packet_put_cstring(options.kbd_interactive_devices ? 1368 options.kbd_interactive_devices : ""); 1369 packet_send(); 1370 1371 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1372 return 1; 1373} 1374 1375/* 1376 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1377 */ 1378void 1379input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1380{ 1381 Authctxt *authctxt = ctxt; 1382 char *name, *inst, *lang, *prompt, *response; 1383 u_int num_prompts, i; 1384 int echo = 0; 1385 1386 debug2("input_userauth_info_req"); 1387 1388 if (authctxt == NULL) 1389 fatal("input_userauth_info_req: no authentication context"); 1390 1391 authctxt->info_req_seen = 1; 1392 1393 name = packet_get_string(NULL); 1394 inst = packet_get_string(NULL); 1395 lang = packet_get_string(NULL); 1396 if (strlen(name) > 0) 1397 logit("%s", name); 1398 if (strlen(inst) > 0) 1399 logit("%s", inst); 1400 free(name); 1401 free(inst); 1402 free(lang); 1403 1404 num_prompts = packet_get_int(); 1405 /* 1406 * Begin to build info response packet based on prompts requested. 1407 * We commit to providing the correct number of responses, so if 1408 * further on we run into a problem that prevents this, we have to 1409 * be sure and clean this up and send a correct error response. 1410 */ 1411 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1412 packet_put_int(num_prompts); 1413 1414 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1415 for (i = 0; i < num_prompts; i++) { 1416 prompt = packet_get_string(NULL); 1417 echo = packet_get_char(); 1418 1419 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1420 1421 packet_put_cstring(response); 1422 explicit_bzero(response, strlen(response)); 1423 free(response); 1424 free(prompt); 1425 } 1426 packet_check_eom(); /* done with parsing incoming message. */ 1427 1428 packet_add_padding(64); 1429 packet_send(); 1430} 1431 1432static int 1433ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1434 u_char *data, u_int datalen) 1435{ 1436 Buffer b; 1437 struct stat st; 1438 pid_t pid; 1439 int to[2], from[2], status, version = 2; 1440 1441 debug2("ssh_keysign called"); 1442 1443 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1444 error("ssh_keysign: not installed: %s", strerror(errno)); 1445 return -1; 1446 } 1447 if (fflush(stdout) != 0) 1448 error("ssh_keysign: fflush: %s", strerror(errno)); 1449 if (pipe(to) < 0) { 1450 error("ssh_keysign: pipe: %s", strerror(errno)); 1451 return -1; 1452 } 1453 if (pipe(from) < 0) { 1454 error("ssh_keysign: pipe: %s", strerror(errno)); 1455 return -1; 1456 } 1457 if ((pid = fork()) < 0) { 1458 error("ssh_keysign: fork: %s", strerror(errno)); 1459 return -1; 1460 } 1461 if (pid == 0) { 1462 /* keep the socket on exec */ 1463 fcntl(packet_get_connection_in(), F_SETFD, 0); 1464 permanently_drop_suid(getuid()); 1465 close(from[0]); 1466 if (dup2(from[1], STDOUT_FILENO) < 0) 1467 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1468 close(to[1]); 1469 if (dup2(to[0], STDIN_FILENO) < 0) 1470 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1471 close(from[1]); 1472 close(to[0]); 1473 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1474 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1475 strerror(errno)); 1476 } 1477 close(from[1]); 1478 close(to[0]); 1479 1480 buffer_init(&b); 1481 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1482 buffer_put_string(&b, data, datalen); 1483 if (ssh_msg_send(to[1], version, &b) == -1) 1484 fatal("ssh_keysign: couldn't send request"); 1485 1486 if (ssh_msg_recv(from[0], &b) < 0) { 1487 error("ssh_keysign: no reply"); 1488 buffer_free(&b); 1489 return -1; 1490 } 1491 close(from[0]); 1492 close(to[1]); 1493 1494 while (waitpid(pid, &status, 0) < 0) 1495 if (errno != EINTR) 1496 break; 1497 1498 if (buffer_get_char(&b) != version) { 1499 error("ssh_keysign: bad version"); 1500 buffer_free(&b); 1501 return -1; 1502 } 1503 *sigp = buffer_get_string(&b, lenp); 1504 buffer_free(&b); 1505 1506 return 0; 1507} 1508 1509int 1510userauth_hostbased(Authctxt *authctxt) 1511{ 1512 Key *private = NULL; 1513 Sensitive *sensitive = authctxt->sensitive; 1514 Buffer b; 1515 u_char *signature, *blob; 1516 char *chost, *pkalg, *p; 1517 const char *service; 1518 u_int blen, slen; 1519 int ok, i, found = 0; 1520 1521 /* check for a useful key */ 1522 for (i = 0; i < sensitive->nkeys; i++) { 1523 private = sensitive->keys[i]; 1524 if (private && private->type != KEY_RSA1) { 1525 found = 1; 1526 /* we take and free the key */ 1527 sensitive->keys[i] = NULL; 1528 break; 1529 } 1530 } 1531 if (!found) { 1532 debug("No more client hostkeys for hostbased authentication."); 1533 return 0; 1534 } 1535 if (key_to_blob(private, &blob, &blen) == 0) { 1536 key_free(private); 1537 return 0; 1538 } 1539 /* figure out a name for the client host */ 1540 p = get_local_name(packet_get_connection_in()); 1541 if (p == NULL) { 1542 error("userauth_hostbased: cannot get local ipaddr/name"); 1543 key_free(private); 1544 free(blob); 1545 return 0; 1546 } 1547 xasprintf(&chost, "%s.", p); 1548 debug2("userauth_hostbased: chost %s", chost); 1549 free(p); 1550 1551 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1552 authctxt->service; 1553 pkalg = xstrdup(key_ssh_name(private)); 1554 buffer_init(&b); 1555 /* construct data */ 1556 buffer_put_string(&b, session_id2, session_id2_len); 1557 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1558 buffer_put_cstring(&b, authctxt->server_user); 1559 buffer_put_cstring(&b, service); 1560 buffer_put_cstring(&b, authctxt->method->name); 1561 buffer_put_cstring(&b, pkalg); 1562 buffer_put_string(&b, blob, blen); 1563 buffer_put_cstring(&b, chost); 1564 buffer_put_cstring(&b, authctxt->local_user); 1565#ifdef DEBUG_PK 1566 buffer_dump(&b); 1567#endif 1568 if (sensitive->external_keysign) 1569 ok = ssh_keysign(private, &signature, &slen, 1570 buffer_ptr(&b), buffer_len(&b)); 1571 else 1572 ok = key_sign(private, &signature, &slen, 1573 buffer_ptr(&b), buffer_len(&b)); 1574 key_free(private); 1575 buffer_free(&b); 1576 if (ok != 0) { 1577 error("key_sign failed"); 1578 free(chost); 1579 free(pkalg); 1580 free(blob); 1581 return 0; 1582 } 1583 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1584 packet_put_cstring(authctxt->server_user); 1585 packet_put_cstring(authctxt->service); 1586 packet_put_cstring(authctxt->method->name); 1587 packet_put_cstring(pkalg); 1588 packet_put_string(blob, blen); 1589 packet_put_cstring(chost); 1590 packet_put_cstring(authctxt->local_user); 1591 packet_put_string(signature, slen); 1592 explicit_bzero(signature, slen); 1593 free(signature); 1594 free(chost); 1595 free(pkalg); 1596 free(blob); 1597 1598 packet_send(); 1599 return 1; 1600} 1601 1602/* find auth method */ 1603 1604/* 1605 * given auth method name, if configurable options permit this method fill 1606 * in auth_ident field and return true, otherwise return false. 1607 */ 1608static int 1609authmethod_is_enabled(Authmethod *method) 1610{ 1611 if (method == NULL) 1612 return 0; 1613 /* return false if options indicate this method is disabled */ 1614 if (method->enabled == NULL || *method->enabled == 0) 1615 return 0; 1616 /* return false if batch mode is enabled but method needs interactive mode */ 1617 if (method->batch_flag != NULL && *method->batch_flag != 0) 1618 return 0; 1619 return 1; 1620} 1621 1622static Authmethod * 1623authmethod_lookup(const char *name) 1624{ 1625 Authmethod *method = NULL; 1626 if (name != NULL) 1627 for (method = authmethods; method->name != NULL; method++) 1628 if (strcmp(name, method->name) == 0) 1629 return method; 1630 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1631 return NULL; 1632} 1633 1634/* XXX internal state */ 1635static Authmethod *current = NULL; 1636static char *supported = NULL; 1637static char *preferred = NULL; 1638 1639/* 1640 * Given the authentication method list sent by the server, return the 1641 * next method we should try. If the server initially sends a nil list, 1642 * use a built-in default list. 1643 */ 1644static Authmethod * 1645authmethod_get(char *authlist) 1646{ 1647 char *name = NULL; 1648 u_int next; 1649 1650 /* Use a suitable default if we're passed a nil list. */ 1651 if (authlist == NULL || strlen(authlist) == 0) 1652 authlist = options.preferred_authentications; 1653 1654 if (supported == NULL || strcmp(authlist, supported) != 0) { 1655 debug3("start over, passed a different list %s", authlist); 1656 free(supported); 1657 supported = xstrdup(authlist); 1658 preferred = options.preferred_authentications; 1659 debug3("preferred %s", preferred); 1660 current = NULL; 1661 } else if (current != NULL && authmethod_is_enabled(current)) 1662 return current; 1663 1664 for (;;) { 1665 if ((name = match_list(preferred, supported, &next)) == NULL) { 1666 debug("No more authentication methods to try."); 1667 current = NULL; 1668 return NULL; 1669 } 1670 preferred += next; 1671 debug3("authmethod_lookup %s", name); 1672 debug3("remaining preferred: %s", preferred); 1673 if ((current = authmethod_lookup(name)) != NULL && 1674 authmethod_is_enabled(current)) { 1675 debug3("authmethod_is_enabled %s", name); 1676 debug("Next authentication method: %s", name); 1677 free(name); 1678 return current; 1679 } 1680 free(name); 1681 } 1682} 1683 1684static char * 1685authmethods_get(void) 1686{ 1687 Authmethod *method = NULL; 1688 Buffer b; 1689 char *list; 1690 1691 buffer_init(&b); 1692 for (method = authmethods; method->name != NULL; method++) { 1693 if (authmethod_is_enabled(method)) { 1694 if (buffer_len(&b) > 0) 1695 buffer_append(&b, ",", 1); 1696 buffer_append(&b, method->name, strlen(method->name)); 1697 } 1698 } 1699 buffer_append(&b, "\0", 1); 1700 list = xstrdup(buffer_ptr(&b)); 1701 buffer_free(&b); 1702 return list; 1703} 1704 1705