sshconnect2.c revision 262566
1/* $OpenBSD: sshconnect2.c,v 1.201 2014/01/09 23:20:00 djm Exp $ */ 2/* $FreeBSD: stable/10/crypto/openssh/sshconnect2.c 262566 2014-02-27 17:29:02Z 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#include "schnorr.h" 75#include "jpake.h" 76 77#ifdef GSSAPI 78#include "ssh-gss.h" 79#endif 80 81/* import */ 82extern char *client_version_string; 83extern char *server_version_string; 84extern Options options; 85#ifdef NONE_CIPHER_ENABLED 86extern Kex *xxx_kex; 87 88/* 89 * tty_flag is set in ssh.c so we can use it here. If set then prevent 90 * the switch to the null cipher. 91 */ 92 93extern int tty_flag; 94#endif 95 96/* 97 * SSH2 key exchange 98 */ 99 100u_char *session_id2 = NULL; 101u_int session_id2_len = 0; 102 103char *xxx_host; 104struct sockaddr *xxx_hostaddr; 105 106Kex *xxx_kex = NULL; 107 108static int 109verify_host_key_callback(Key *hostkey) 110{ 111 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 112 fatal("Host key verification failed."); 113 return 0; 114} 115 116static char * 117order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 118{ 119 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 120 size_t maxlen; 121 struct hostkeys *hostkeys; 122 int ktype; 123 u_int i; 124 125 /* Find all hostkeys for this hostname */ 126 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 127 hostkeys = init_hostkeys(); 128 for (i = 0; i < options.num_user_hostfiles; i++) 129 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 130 for (i = 0; i < options.num_system_hostfiles; i++) 131 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 132 133 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 134 maxlen = strlen(avail) + 1; 135 first = xmalloc(maxlen); 136 last = xmalloc(maxlen); 137 *first = *last = '\0'; 138 139#define ALG_APPEND(to, from) \ 140 do { \ 141 if (*to != '\0') \ 142 strlcat(to, ",", maxlen); \ 143 strlcat(to, from, maxlen); \ 144 } while (0) 145 146 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 147 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 148 fatal("%s: unknown alg %s", __func__, alg); 149 if (lookup_key_in_hostkeys_by_type(hostkeys, 150 key_type_plain(ktype), NULL)) 151 ALG_APPEND(first, alg); 152 else 153 ALG_APPEND(last, alg); 154 } 155#undef ALG_APPEND 156 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 157 if (*first != '\0') 158 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 159 160 free(first); 161 free(last); 162 free(hostname); 163 free(oavail); 164 free_hostkeys(hostkeys); 165 166 return ret; 167} 168 169void 170ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 171{ 172 Kex *kex; 173 174 xxx_host = host; 175 xxx_hostaddr = hostaddr; 176 177 if (options.ciphers == (char *)-1) { 178 logit("No valid ciphers for protocol version 2 given, using defaults."); 179 options.ciphers = NULL; 180 } 181 if (options.ciphers != NULL) { 182 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 183 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 184 } 185 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 186 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 187 myproposal[PROPOSAL_ENC_ALGS_STOC] = 188 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 189 if (options.compression) { 190 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 191 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 192 } else { 193 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 194 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 195 } 196 if (options.macs != NULL) { 197 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 198 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 199 } 200 if (options.hostkeyalgorithms != NULL) 201 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 202 compat_pkalg_proposal(options.hostkeyalgorithms); 203 else { 204 /* Prefer algorithms that we already have keys for */ 205 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 206 compat_pkalg_proposal( 207 order_hostkeyalgs(host, hostaddr, port)); 208 } 209 if (options.kex_algorithms != NULL) 210 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 211 212 if (options.rekey_limit || options.rekey_interval) 213 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 214 (time_t)options.rekey_interval); 215 216 /* start key exchange */ 217 kex = kex_setup(myproposal); 218 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 219 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 220 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 221 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 222 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 223 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 224 kex->client_version_string=client_version_string; 225 kex->server_version_string=server_version_string; 226 kex->verify_host_key=&verify_host_key_callback; 227 228 xxx_kex = kex; 229 230 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 231 232 if (options.use_roaming && !kex->roaming) { 233 debug("Roaming not allowed by server"); 234 options.use_roaming = 0; 235 } 236 237 session_id2 = kex->session_id; 238 session_id2_len = kex->session_id_len; 239 240#ifdef DEBUG_KEXDH 241 /* send 1st encrypted/maced/compressed message */ 242 packet_start(SSH2_MSG_IGNORE); 243 packet_put_cstring("markus"); 244 packet_send(); 245 packet_write_wait(); 246#endif 247} 248 249/* 250 * Authenticate user 251 */ 252 253typedef struct Authctxt Authctxt; 254typedef struct Authmethod Authmethod; 255typedef struct identity Identity; 256typedef struct idlist Idlist; 257 258struct identity { 259 TAILQ_ENTRY(identity) next; 260 AuthenticationConnection *ac; /* set if agent supports key */ 261 Key *key; /* public/private key */ 262 char *filename; /* comment for agent-only keys */ 263 int tried; 264 int isprivate; /* key points to the private key */ 265 int userprovided; 266}; 267TAILQ_HEAD(idlist, identity); 268 269struct Authctxt { 270 const char *server_user; 271 const char *local_user; 272 const char *host; 273 const char *service; 274 Authmethod *method; 275 sig_atomic_t success; 276 char *authlist; 277 /* pubkey */ 278 Idlist keys; 279 AuthenticationConnection *agent; 280 /* hostbased */ 281 Sensitive *sensitive; 282 /* kbd-interactive */ 283 int info_req_seen; 284 /* generic */ 285 void *methoddata; 286}; 287struct Authmethod { 288 char *name; /* string to compare against server's list */ 289 int (*userauth)(Authctxt *authctxt); 290 void (*cleanup)(Authctxt *authctxt); 291 int *enabled; /* flag in option struct that enables method */ 292 int *batch_flag; /* flag in option struct that disables method */ 293}; 294 295void input_userauth_success(int, u_int32_t, void *); 296void input_userauth_success_unexpected(int, u_int32_t, void *); 297void input_userauth_failure(int, u_int32_t, void *); 298void input_userauth_banner(int, u_int32_t, void *); 299void input_userauth_error(int, u_int32_t, void *); 300void input_userauth_info_req(int, u_int32_t, void *); 301void input_userauth_pk_ok(int, u_int32_t, void *); 302void input_userauth_passwd_changereq(int, u_int32_t, void *); 303void input_userauth_jpake_server_step1(int, u_int32_t, void *); 304void input_userauth_jpake_server_step2(int, u_int32_t, void *); 305void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 306 307int userauth_none(Authctxt *); 308int userauth_pubkey(Authctxt *); 309int userauth_passwd(Authctxt *); 310int userauth_kbdint(Authctxt *); 311int userauth_hostbased(Authctxt *); 312int userauth_jpake(Authctxt *); 313 314void userauth_jpake_cleanup(Authctxt *); 315 316#ifdef GSSAPI 317int userauth_gssapi(Authctxt *authctxt); 318void input_gssapi_response(int type, u_int32_t, void *); 319void input_gssapi_token(int type, u_int32_t, void *); 320void input_gssapi_hash(int type, u_int32_t, void *); 321void input_gssapi_error(int, u_int32_t, void *); 322void input_gssapi_errtok(int, u_int32_t, void *); 323#endif 324 325void userauth(Authctxt *, char *); 326 327static int sign_and_send_pubkey(Authctxt *, Identity *); 328static void pubkey_prepare(Authctxt *); 329static void pubkey_cleanup(Authctxt *); 330static Key *load_identity_file(char *, int); 331 332static Authmethod *authmethod_get(char *authlist); 333static Authmethod *authmethod_lookup(const char *name); 334static char *authmethods_get(void); 335 336Authmethod authmethods[] = { 337#ifdef GSSAPI 338 {"gssapi-with-mic", 339 userauth_gssapi, 340 NULL, 341 &options.gss_authentication, 342 NULL}, 343#endif 344 {"hostbased", 345 userauth_hostbased, 346 NULL, 347 &options.hostbased_authentication, 348 NULL}, 349 {"publickey", 350 userauth_pubkey, 351 NULL, 352 &options.pubkey_authentication, 353 NULL}, 354#ifdef JPAKE 355 {"jpake-01@openssh.com", 356 userauth_jpake, 357 userauth_jpake_cleanup, 358 &options.zero_knowledge_password_authentication, 359 &options.batch_mode}, 360#endif 361 {"keyboard-interactive", 362 userauth_kbdint, 363 NULL, 364 &options.kbd_interactive_authentication, 365 &options.batch_mode}, 366 {"password", 367 userauth_passwd, 368 NULL, 369 &options.password_authentication, 370 &options.batch_mode}, 371 {"none", 372 userauth_none, 373 NULL, 374 NULL, 375 NULL}, 376 {NULL, NULL, NULL, NULL, NULL} 377}; 378 379void 380ssh_userauth2(const char *local_user, const char *server_user, char *host, 381 Sensitive *sensitive) 382{ 383 Authctxt authctxt; 384 int type; 385 386 if (options.challenge_response_authentication) 387 options.kbd_interactive_authentication = 1; 388 389 packet_start(SSH2_MSG_SERVICE_REQUEST); 390 packet_put_cstring("ssh-userauth"); 391 packet_send(); 392 debug("SSH2_MSG_SERVICE_REQUEST sent"); 393 packet_write_wait(); 394 type = packet_read(); 395 if (type != SSH2_MSG_SERVICE_ACCEPT) 396 fatal("Server denied authentication request: %d", type); 397 if (packet_remaining() > 0) { 398 char *reply = packet_get_string(NULL); 399 debug2("service_accept: %s", reply); 400 free(reply); 401 } else { 402 debug2("buggy server: service_accept w/o service"); 403 } 404 packet_check_eom(); 405 debug("SSH2_MSG_SERVICE_ACCEPT received"); 406 407 if (options.preferred_authentications == NULL) 408 options.preferred_authentications = authmethods_get(); 409 410 /* setup authentication context */ 411 memset(&authctxt, 0, sizeof(authctxt)); 412 pubkey_prepare(&authctxt); 413 authctxt.server_user = server_user; 414 authctxt.local_user = local_user; 415 authctxt.host = host; 416 authctxt.service = "ssh-connection"; /* service name */ 417 authctxt.success = 0; 418 authctxt.method = authmethod_lookup("none"); 419 authctxt.authlist = NULL; 420 authctxt.methoddata = NULL; 421 authctxt.sensitive = sensitive; 422 authctxt.info_req_seen = 0; 423 if (authctxt.method == NULL) 424 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 425 426 /* initial userauth request */ 427 userauth_none(&authctxt); 428 429 dispatch_init(&input_userauth_error); 430 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 431 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 432 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 433 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 434 435 pubkey_cleanup(&authctxt); 436 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 437 438#ifdef NONE_CIPHER_ENABLED 439 /* 440 * If the user explicitly requests to use the none cipher enable it 441 * post authentication and only if the right conditions are met: both 442 * of the NONE switches must be true and there must be no tty allocated. 443 */ 444 if (options.none_switch == 1 && options.none_enabled == 1) { 445 if (!tty_flag) { 446 debug("Requesting none cipher re-keying..."); 447 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 448 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 449 kex_prop2buf(&xxx_kex->my, myproposal); 450 packet_request_rekeying(); 451 fprintf(stderr, "WARNING: enabled NONE cipher\n"); 452 } else { 453 /* Requested NONE cipher on an interactive session. */ 454 debug("Cannot switch to NONE cipher with tty " 455 "allocated"); 456 fprintf(stderr, "NONE cipher switch disabled given " 457 "a TTY is allocated\n"); 458 } 459 } 460#endif 461 debug("Authentication succeeded (%s).", authctxt.method->name); 462} 463 464void 465userauth(Authctxt *authctxt, char *authlist) 466{ 467 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 468 authctxt->method->cleanup(authctxt); 469 470 free(authctxt->methoddata); 471 authctxt->methoddata = NULL; 472 if (authlist == NULL) { 473 authlist = authctxt->authlist; 474 } else { 475 free(authctxt->authlist); 476 authctxt->authlist = authlist; 477 } 478 for (;;) { 479 Authmethod *method = authmethod_get(authlist); 480 if (method == NULL) 481 fatal("Permission denied (%s).", authlist); 482 authctxt->method = method; 483 484 /* reset the per method handler */ 485 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 486 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 487 488 /* and try new method */ 489 if (method->userauth(authctxt) != 0) { 490 debug2("we sent a %s packet, wait for reply", method->name); 491 break; 492 } else { 493 debug2("we did not send a packet, disable method"); 494 method->enabled = NULL; 495 } 496 } 497} 498 499/* ARGSUSED */ 500void 501input_userauth_error(int type, u_int32_t seq, void *ctxt) 502{ 503 fatal("input_userauth_error: bad message during authentication: " 504 "type %d", type); 505} 506 507/* ARGSUSED */ 508void 509input_userauth_banner(int type, u_int32_t seq, void *ctxt) 510{ 511 char *msg, *raw, *lang; 512 u_int len; 513 514 debug3("input_userauth_banner"); 515 raw = packet_get_string(&len); 516 lang = packet_get_string(NULL); 517 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 518 if (len > 65536) 519 len = 65536; 520 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 521 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 522 fprintf(stderr, "%s", msg); 523 free(msg); 524 } 525 free(raw); 526 free(lang); 527} 528 529/* ARGSUSED */ 530void 531input_userauth_success(int type, u_int32_t seq, void *ctxt) 532{ 533 Authctxt *authctxt = ctxt; 534 535 if (authctxt == NULL) 536 fatal("input_userauth_success: no authentication context"); 537 free(authctxt->authlist); 538 authctxt->authlist = NULL; 539 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 540 authctxt->method->cleanup(authctxt); 541 free(authctxt->methoddata); 542 authctxt->methoddata = NULL; 543 authctxt->success = 1; /* break out */ 544} 545 546void 547input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 548{ 549 Authctxt *authctxt = ctxt; 550 551 if (authctxt == NULL) 552 fatal("%s: no authentication context", __func__); 553 554 fatal("Unexpected authentication success during %s.", 555 authctxt->method->name); 556} 557 558/* ARGSUSED */ 559void 560input_userauth_failure(int type, u_int32_t seq, void *ctxt) 561{ 562 Authctxt *authctxt = ctxt; 563 char *authlist = NULL; 564 int partial; 565 566 if (authctxt == NULL) 567 fatal("input_userauth_failure: no authentication context"); 568 569 authlist = packet_get_string(NULL); 570 partial = packet_get_char(); 571 packet_check_eom(); 572 573 if (partial != 0) { 574 logit("Authenticated with partial success."); 575 /* reset state */ 576 pubkey_cleanup(authctxt); 577 pubkey_prepare(authctxt); 578 } 579 debug("Authentications that can continue: %s", authlist); 580 581 userauth(authctxt, authlist); 582} 583 584/* ARGSUSED */ 585void 586input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 587{ 588 Authctxt *authctxt = ctxt; 589 Key *key = NULL; 590 Identity *id = NULL; 591 Buffer b; 592 int pktype, sent = 0; 593 u_int alen, blen; 594 char *pkalg, *fp; 595 u_char *pkblob; 596 597 if (authctxt == NULL) 598 fatal("input_userauth_pk_ok: no authentication context"); 599 if (datafellows & SSH_BUG_PKOK) { 600 /* this is similar to SSH_BUG_PKAUTH */ 601 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 602 pkblob = packet_get_string(&blen); 603 buffer_init(&b); 604 buffer_append(&b, pkblob, blen); 605 pkalg = buffer_get_string(&b, &alen); 606 buffer_free(&b); 607 } else { 608 pkalg = packet_get_string(&alen); 609 pkblob = packet_get_string(&blen); 610 } 611 packet_check_eom(); 612 613 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 614 615 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 616 debug("unknown pkalg %s", pkalg); 617 goto done; 618 } 619 if ((key = key_from_blob(pkblob, blen)) == NULL) { 620 debug("no key from blob. pkalg %s", pkalg); 621 goto done; 622 } 623 if (key->type != pktype) { 624 error("input_userauth_pk_ok: type mismatch " 625 "for decoded key (received %d, expected %d)", 626 key->type, pktype); 627 goto done; 628 } 629 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 630 debug2("input_userauth_pk_ok: fp %s", fp); 631 free(fp); 632 633 /* 634 * search keys in the reverse order, because last candidate has been 635 * moved to the end of the queue. this also avoids confusion by 636 * duplicate keys 637 */ 638 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 639 if (key_equal(key, id->key)) { 640 sent = sign_and_send_pubkey(authctxt, id); 641 break; 642 } 643 } 644done: 645 if (key != NULL) 646 key_free(key); 647 free(pkalg); 648 free(pkblob); 649 650 /* try another method if we did not send a packet */ 651 if (sent == 0) 652 userauth(authctxt, NULL); 653} 654 655#ifdef GSSAPI 656int 657userauth_gssapi(Authctxt *authctxt) 658{ 659 Gssctxt *gssctxt = NULL; 660 static gss_OID_set gss_supported = NULL; 661 static u_int mech = 0; 662 OM_uint32 min; 663 int ok = 0; 664 665 /* Try one GSSAPI method at a time, rather than sending them all at 666 * once. */ 667 668 if (gss_supported == NULL) 669 gss_indicate_mechs(&min, &gss_supported); 670 671 /* Check to see if the mechanism is usable before we offer it */ 672 while (mech < gss_supported->count && !ok) { 673 /* My DER encoding requires length<128 */ 674 if (gss_supported->elements[mech].length < 128 && 675 ssh_gssapi_check_mechanism(&gssctxt, 676 &gss_supported->elements[mech], authctxt->host)) { 677 ok = 1; /* Mechanism works */ 678 } else { 679 mech++; 680 } 681 } 682 683 if (!ok) 684 return 0; 685 686 authctxt->methoddata=(void *)gssctxt; 687 688 packet_start(SSH2_MSG_USERAUTH_REQUEST); 689 packet_put_cstring(authctxt->server_user); 690 packet_put_cstring(authctxt->service); 691 packet_put_cstring(authctxt->method->name); 692 693 packet_put_int(1); 694 695 packet_put_int((gss_supported->elements[mech].length) + 2); 696 packet_put_char(SSH_GSS_OIDTYPE); 697 packet_put_char(gss_supported->elements[mech].length); 698 packet_put_raw(gss_supported->elements[mech].elements, 699 gss_supported->elements[mech].length); 700 701 packet_send(); 702 703 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 704 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 705 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 706 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 707 708 mech++; /* Move along to next candidate */ 709 710 return 1; 711} 712 713static OM_uint32 714process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 715{ 716 Authctxt *authctxt = ctxt; 717 Gssctxt *gssctxt = authctxt->methoddata; 718 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 719 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 720 gss_buffer_desc gssbuf; 721 OM_uint32 status, ms, flags; 722 Buffer b; 723 724 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 725 recv_tok, &send_tok, &flags); 726 727 if (send_tok.length > 0) { 728 if (GSS_ERROR(status)) 729 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 730 else 731 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 732 733 packet_put_string(send_tok.value, send_tok.length); 734 packet_send(); 735 gss_release_buffer(&ms, &send_tok); 736 } 737 738 if (status == GSS_S_COMPLETE) { 739 /* send either complete or MIC, depending on mechanism */ 740 if (!(flags & GSS_C_INTEG_FLAG)) { 741 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 742 packet_send(); 743 } else { 744 ssh_gssapi_buildmic(&b, authctxt->server_user, 745 authctxt->service, "gssapi-with-mic"); 746 747 gssbuf.value = buffer_ptr(&b); 748 gssbuf.length = buffer_len(&b); 749 750 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 751 752 if (!GSS_ERROR(status)) { 753 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 754 packet_put_string(mic.value, mic.length); 755 756 packet_send(); 757 } 758 759 buffer_free(&b); 760 gss_release_buffer(&ms, &mic); 761 } 762 } 763 764 return status; 765} 766 767/* ARGSUSED */ 768void 769input_gssapi_response(int type, u_int32_t plen, void *ctxt) 770{ 771 Authctxt *authctxt = ctxt; 772 Gssctxt *gssctxt; 773 int oidlen; 774 char *oidv; 775 776 if (authctxt == NULL) 777 fatal("input_gssapi_response: no authentication context"); 778 gssctxt = authctxt->methoddata; 779 780 /* Setup our OID */ 781 oidv = packet_get_string(&oidlen); 782 783 if (oidlen <= 2 || 784 oidv[0] != SSH_GSS_OIDTYPE || 785 oidv[1] != oidlen - 2) { 786 free(oidv); 787 debug("Badly encoded mechanism OID received"); 788 userauth(authctxt, NULL); 789 return; 790 } 791 792 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 793 fatal("Server returned different OID than expected"); 794 795 packet_check_eom(); 796 797 free(oidv); 798 799 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 800 /* Start again with next method on list */ 801 debug("Trying to start again"); 802 userauth(authctxt, NULL); 803 return; 804 } 805} 806 807/* ARGSUSED */ 808void 809input_gssapi_token(int type, u_int32_t plen, void *ctxt) 810{ 811 Authctxt *authctxt = ctxt; 812 gss_buffer_desc recv_tok; 813 OM_uint32 status; 814 u_int slen; 815 816 if (authctxt == NULL) 817 fatal("input_gssapi_response: no authentication context"); 818 819 recv_tok.value = packet_get_string(&slen); 820 recv_tok.length = slen; /* safe typecast */ 821 822 packet_check_eom(); 823 824 status = process_gssapi_token(ctxt, &recv_tok); 825 826 free(recv_tok.value); 827 828 if (GSS_ERROR(status)) { 829 /* Start again with the next method in the list */ 830 userauth(authctxt, NULL); 831 return; 832 } 833} 834 835/* ARGSUSED */ 836void 837input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 838{ 839 Authctxt *authctxt = ctxt; 840 Gssctxt *gssctxt; 841 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 842 gss_buffer_desc recv_tok; 843 OM_uint32 ms; 844 u_int len; 845 846 if (authctxt == NULL) 847 fatal("input_gssapi_response: no authentication context"); 848 gssctxt = authctxt->methoddata; 849 850 recv_tok.value = packet_get_string(&len); 851 recv_tok.length = len; 852 853 packet_check_eom(); 854 855 /* Stick it into GSSAPI and see what it says */ 856 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 857 &recv_tok, &send_tok, NULL); 858 859 free(recv_tok.value); 860 gss_release_buffer(&ms, &send_tok); 861 862 /* Server will be returning a failed packet after this one */ 863} 864 865/* ARGSUSED */ 866void 867input_gssapi_error(int type, u_int32_t plen, void *ctxt) 868{ 869 char *msg; 870 char *lang; 871 872 /* maj */(void)packet_get_int(); 873 /* min */(void)packet_get_int(); 874 msg=packet_get_string(NULL); 875 lang=packet_get_string(NULL); 876 877 packet_check_eom(); 878 879 debug("Server GSSAPI Error:\n%s", msg); 880 free(msg); 881 free(lang); 882} 883#endif /* GSSAPI */ 884 885int 886userauth_none(Authctxt *authctxt) 887{ 888 /* initial userauth request */ 889 packet_start(SSH2_MSG_USERAUTH_REQUEST); 890 packet_put_cstring(authctxt->server_user); 891 packet_put_cstring(authctxt->service); 892 packet_put_cstring(authctxt->method->name); 893 packet_send(); 894 return 1; 895} 896 897int 898userauth_passwd(Authctxt *authctxt) 899{ 900 static int attempt = 0; 901 char prompt[150]; 902 char *password; 903 const char *host = options.host_key_alias ? options.host_key_alias : 904 authctxt->host; 905 906 if (attempt++ >= options.number_of_password_prompts) 907 return 0; 908 909 if (attempt != 1) 910 error("Permission denied, please try again."); 911 912 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 913 authctxt->server_user, host); 914 password = read_passphrase(prompt, 0); 915 packet_start(SSH2_MSG_USERAUTH_REQUEST); 916 packet_put_cstring(authctxt->server_user); 917 packet_put_cstring(authctxt->service); 918 packet_put_cstring(authctxt->method->name); 919 packet_put_char(0); 920 packet_put_cstring(password); 921 memset(password, 0, strlen(password)); 922 free(password); 923 packet_add_padding(64); 924 packet_send(); 925 926 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 927 &input_userauth_passwd_changereq); 928 929 return 1; 930} 931 932/* 933 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 934 */ 935/* ARGSUSED */ 936void 937input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 938{ 939 Authctxt *authctxt = ctxt; 940 char *info, *lang, *password = NULL, *retype = NULL; 941 char prompt[150]; 942 const char *host = options.host_key_alias ? options.host_key_alias : 943 authctxt->host; 944 945 debug2("input_userauth_passwd_changereq"); 946 947 if (authctxt == NULL) 948 fatal("input_userauth_passwd_changereq: " 949 "no authentication context"); 950 951 info = packet_get_string(NULL); 952 lang = packet_get_string(NULL); 953 if (strlen(info) > 0) 954 logit("%s", info); 955 free(info); 956 free(lang); 957 packet_start(SSH2_MSG_USERAUTH_REQUEST); 958 packet_put_cstring(authctxt->server_user); 959 packet_put_cstring(authctxt->service); 960 packet_put_cstring(authctxt->method->name); 961 packet_put_char(1); /* additional info */ 962 snprintf(prompt, sizeof(prompt), 963 "Enter %.30s@%.128s's old password: ", 964 authctxt->server_user, host); 965 password = read_passphrase(prompt, 0); 966 packet_put_cstring(password); 967 memset(password, 0, strlen(password)); 968 free(password); 969 password = NULL; 970 while (password == NULL) { 971 snprintf(prompt, sizeof(prompt), 972 "Enter %.30s@%.128s's new password: ", 973 authctxt->server_user, host); 974 password = read_passphrase(prompt, RP_ALLOW_EOF); 975 if (password == NULL) { 976 /* bail out */ 977 return; 978 } 979 snprintf(prompt, sizeof(prompt), 980 "Retype %.30s@%.128s's new password: ", 981 authctxt->server_user, host); 982 retype = read_passphrase(prompt, 0); 983 if (strcmp(password, retype) != 0) { 984 memset(password, 0, strlen(password)); 985 free(password); 986 logit("Mismatch; try again, EOF to quit."); 987 password = NULL; 988 } 989 memset(retype, 0, strlen(retype)); 990 free(retype); 991 } 992 packet_put_cstring(password); 993 memset(password, 0, strlen(password)); 994 free(password); 995 packet_add_padding(64); 996 packet_send(); 997 998 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 999 &input_userauth_passwd_changereq); 1000} 1001 1002#ifdef JPAKE 1003static char * 1004pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 1005{ 1006 /* OpenBSD crypt(3) handles all of these */ 1007 if (strcmp(crypt_scheme, "crypt") == 0 || 1008 strcmp(crypt_scheme, "bcrypt") == 0 || 1009 strcmp(crypt_scheme, "md5crypt") == 0 || 1010 strcmp(crypt_scheme, "crypt-extended") == 0) 1011 return xstrdup(crypt(password, salt)); 1012 error("%s: unsupported password encryption scheme \"%.100s\"", 1013 __func__, crypt_scheme); 1014 return NULL; 1015} 1016 1017static BIGNUM * 1018jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 1019 const char *salt) 1020{ 1021 char prompt[256], *password, *crypted; 1022 u_char *secret; 1023 u_int secret_len; 1024 BIGNUM *ret; 1025 1026 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 1027 authctxt->server_user, authctxt->host); 1028 password = read_passphrase(prompt, 0); 1029 1030 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 1031 logit("Disabling %s authentication", authctxt->method->name); 1032 authctxt->method->enabled = NULL; 1033 /* Continue with an empty password to fail gracefully */ 1034 crypted = xstrdup(""); 1035 } 1036 1037#ifdef JPAKE_DEBUG 1038 debug3("%s: salt = %s", __func__, salt); 1039 debug3("%s: scheme = %s", __func__, crypt_scheme); 1040 debug3("%s: crypted = %s", __func__, crypted); 1041#endif 1042 1043 if (hash_buffer(crypted, strlen(crypted), SSH_DIGEST_SHA1, 1044 &secret, &secret_len) != 0) 1045 fatal("%s: hash_buffer", __func__); 1046 1047 bzero(password, strlen(password)); 1048 bzero(crypted, strlen(crypted)); 1049 free(password); 1050 free(crypted); 1051 1052 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 1053 fatal("%s: BN_bin2bn (secret)", __func__); 1054 bzero(secret, secret_len); 1055 free(secret); 1056 1057 return ret; 1058} 1059 1060/* ARGSUSED */ 1061void 1062input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 1063{ 1064 Authctxt *authctxt = ctxt; 1065 struct jpake_ctx *pctx = authctxt->methoddata; 1066 u_char *x3_proof, *x4_proof, *x2_s_proof; 1067 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1068 char *crypt_scheme, *salt; 1069 1070 /* Disable this message */ 1071 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1072 1073 if ((pctx->g_x3 = BN_new()) == NULL || 1074 (pctx->g_x4 = BN_new()) == NULL) 1075 fatal("%s: BN_new", __func__); 1076 1077 /* Fetch step 1 values */ 1078 crypt_scheme = packet_get_string(NULL); 1079 salt = packet_get_string(NULL); 1080 pctx->server_id = packet_get_string(&pctx->server_id_len); 1081 packet_get_bignum2(pctx->g_x3); 1082 packet_get_bignum2(pctx->g_x4); 1083 x3_proof = packet_get_string(&x3_proof_len); 1084 x4_proof = packet_get_string(&x4_proof_len); 1085 packet_check_eom(); 1086 1087 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1088 1089 /* Obtain password and derive secret */ 1090 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1091 bzero(crypt_scheme, strlen(crypt_scheme)); 1092 bzero(salt, strlen(salt)); 1093 free(crypt_scheme); 1094 free(salt); 1095 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1096 1097 /* Calculate step 2 values */ 1098 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1099 pctx->g_x3, pctx->g_x4, pctx->x2, 1100 pctx->server_id, pctx->server_id_len, 1101 pctx->client_id, pctx->client_id_len, 1102 x3_proof, x3_proof_len, 1103 x4_proof, x4_proof_len, 1104 &pctx->a, 1105 &x2_s_proof, &x2_s_proof_len); 1106 1107 bzero(x3_proof, x3_proof_len); 1108 bzero(x4_proof, x4_proof_len); 1109 free(x3_proof); 1110 free(x4_proof); 1111 1112 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1113 1114 /* Send values for step 2 */ 1115 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1116 packet_put_bignum2(pctx->a); 1117 packet_put_string(x2_s_proof, x2_s_proof_len); 1118 packet_send(); 1119 1120 bzero(x2_s_proof, x2_s_proof_len); 1121 free(x2_s_proof); 1122 1123 /* Expect step 2 packet from peer */ 1124 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1125 input_userauth_jpake_server_step2); 1126} 1127 1128/* ARGSUSED */ 1129void 1130input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1131{ 1132 Authctxt *authctxt = ctxt; 1133 struct jpake_ctx *pctx = authctxt->methoddata; 1134 u_char *x4_s_proof; 1135 u_int x4_s_proof_len; 1136 1137 /* Disable this message */ 1138 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1139 1140 if ((pctx->b = BN_new()) == NULL) 1141 fatal("%s: BN_new", __func__); 1142 1143 /* Fetch step 2 values */ 1144 packet_get_bignum2(pctx->b); 1145 x4_s_proof = packet_get_string(&x4_s_proof_len); 1146 packet_check_eom(); 1147 1148 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1149 1150 /* Derive shared key and calculate confirmation hash */ 1151 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1152 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1153 pctx->client_id, pctx->client_id_len, 1154 pctx->server_id, pctx->server_id_len, 1155 session_id2, session_id2_len, 1156 x4_s_proof, x4_s_proof_len, 1157 &pctx->k, 1158 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1159 1160 bzero(x4_s_proof, x4_s_proof_len); 1161 free(x4_s_proof); 1162 1163 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1164 1165 /* Send key confirmation proof */ 1166 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1167 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1168 packet_send(); 1169 1170 /* Expect confirmation from peer */ 1171 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1172 input_userauth_jpake_server_confirm); 1173} 1174 1175/* ARGSUSED */ 1176void 1177input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1178{ 1179 Authctxt *authctxt = ctxt; 1180 struct jpake_ctx *pctx = authctxt->methoddata; 1181 1182 /* Disable this message */ 1183 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1184 1185 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1186 packet_check_eom(); 1187 1188 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1189 1190 /* Verify expected confirmation hash */ 1191 if (jpake_check_confirm(pctx->k, 1192 pctx->server_id, pctx->server_id_len, 1193 session_id2, session_id2_len, 1194 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1195 debug("%s: %s success", __func__, authctxt->method->name); 1196 else { 1197 debug("%s: confirmation mismatch", __func__); 1198 /* XXX stash this so if auth succeeds then we can warn/kill */ 1199 } 1200 1201 userauth_jpake_cleanup(authctxt); 1202} 1203#endif /* JPAKE */ 1204 1205static int 1206identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1207 u_char *data, u_int datalen) 1208{ 1209 Key *prv; 1210 int ret; 1211 1212 /* the agent supports this key */ 1213 if (id->ac) 1214 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1215 data, datalen)); 1216 /* 1217 * we have already loaded the private key or 1218 * the private key is stored in external hardware 1219 */ 1220 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1221 return (key_sign(id->key, sigp, lenp, data, datalen)); 1222 /* load the private key from the file */ 1223 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 1224 return (-1); 1225 ret = key_sign(prv, sigp, lenp, data, datalen); 1226 key_free(prv); 1227 return (ret); 1228} 1229 1230static int 1231sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1232{ 1233 Buffer b; 1234 u_char *blob, *signature; 1235 u_int bloblen, slen; 1236 u_int skip = 0; 1237 int ret = -1; 1238 int have_sig = 1; 1239 char *fp; 1240 1241 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1242 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1243 free(fp); 1244 1245 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1246 /* we cannot handle this key */ 1247 debug3("sign_and_send_pubkey: cannot handle key"); 1248 return 0; 1249 } 1250 /* data to be signed */ 1251 buffer_init(&b); 1252 if (datafellows & SSH_OLD_SESSIONID) { 1253 buffer_append(&b, session_id2, session_id2_len); 1254 skip = session_id2_len; 1255 } else { 1256 buffer_put_string(&b, session_id2, session_id2_len); 1257 skip = buffer_len(&b); 1258 } 1259 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1260 buffer_put_cstring(&b, authctxt->server_user); 1261 buffer_put_cstring(&b, 1262 datafellows & SSH_BUG_PKSERVICE ? 1263 "ssh-userauth" : 1264 authctxt->service); 1265 if (datafellows & SSH_BUG_PKAUTH) { 1266 buffer_put_char(&b, have_sig); 1267 } else { 1268 buffer_put_cstring(&b, authctxt->method->name); 1269 buffer_put_char(&b, have_sig); 1270 buffer_put_cstring(&b, key_ssh_name(id->key)); 1271 } 1272 buffer_put_string(&b, blob, bloblen); 1273 1274 /* generate signature */ 1275 ret = identity_sign(id, &signature, &slen, 1276 buffer_ptr(&b), buffer_len(&b)); 1277 if (ret == -1) { 1278 free(blob); 1279 buffer_free(&b); 1280 return 0; 1281 } 1282#ifdef DEBUG_PK 1283 buffer_dump(&b); 1284#endif 1285 if (datafellows & SSH_BUG_PKSERVICE) { 1286 buffer_clear(&b); 1287 buffer_append(&b, session_id2, session_id2_len); 1288 skip = session_id2_len; 1289 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1290 buffer_put_cstring(&b, authctxt->server_user); 1291 buffer_put_cstring(&b, authctxt->service); 1292 buffer_put_cstring(&b, authctxt->method->name); 1293 buffer_put_char(&b, have_sig); 1294 if (!(datafellows & SSH_BUG_PKAUTH)) 1295 buffer_put_cstring(&b, key_ssh_name(id->key)); 1296 buffer_put_string(&b, blob, bloblen); 1297 } 1298 free(blob); 1299 1300 /* append signature */ 1301 buffer_put_string(&b, signature, slen); 1302 free(signature); 1303 1304 /* skip session id and packet type */ 1305 if (buffer_len(&b) < skip + 1) 1306 fatal("userauth_pubkey: internal error"); 1307 buffer_consume(&b, skip + 1); 1308 1309 /* put remaining data from buffer into packet */ 1310 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1311 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1312 buffer_free(&b); 1313 packet_send(); 1314 1315 return 1; 1316} 1317 1318static int 1319send_pubkey_test(Authctxt *authctxt, Identity *id) 1320{ 1321 u_char *blob; 1322 u_int bloblen, have_sig = 0; 1323 1324 debug3("send_pubkey_test"); 1325 1326 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1327 /* we cannot handle this key */ 1328 debug3("send_pubkey_test: cannot handle key"); 1329 return 0; 1330 } 1331 /* register callback for USERAUTH_PK_OK message */ 1332 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1333 1334 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1335 packet_put_cstring(authctxt->server_user); 1336 packet_put_cstring(authctxt->service); 1337 packet_put_cstring(authctxt->method->name); 1338 packet_put_char(have_sig); 1339 if (!(datafellows & SSH_BUG_PKAUTH)) 1340 packet_put_cstring(key_ssh_name(id->key)); 1341 packet_put_string(blob, bloblen); 1342 free(blob); 1343 packet_send(); 1344 return 1; 1345} 1346 1347static Key * 1348load_identity_file(char *filename, int userprovided) 1349{ 1350 Key *private; 1351 char prompt[300], *passphrase; 1352 int perm_ok = 0, quit, i; 1353 struct stat st; 1354 1355 if (stat(filename, &st) < 0) { 1356 (userprovided ? logit : debug3)("no such identity: %s: %s", 1357 filename, strerror(errno)); 1358 return NULL; 1359 } 1360 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1361 if (!perm_ok) { 1362 if (private != NULL) 1363 key_free(private); 1364 return NULL; 1365 } 1366 if (private == NULL) { 1367 if (options.batch_mode) 1368 return NULL; 1369 snprintf(prompt, sizeof prompt, 1370 "Enter passphrase for key '%.100s': ", filename); 1371 for (i = 0; i < options.number_of_password_prompts; i++) { 1372 passphrase = read_passphrase(prompt, 0); 1373 if (strcmp(passphrase, "") != 0) { 1374 private = key_load_private_type(KEY_UNSPEC, 1375 filename, passphrase, NULL, NULL); 1376 quit = 0; 1377 } else { 1378 debug2("no passphrase given, try next key"); 1379 quit = 1; 1380 } 1381 memset(passphrase, 0, strlen(passphrase)); 1382 free(passphrase); 1383 if (private != NULL || quit) 1384 break; 1385 debug2("bad passphrase given, try again..."); 1386 } 1387 } 1388 return private; 1389} 1390 1391/* 1392 * try keys in the following order: 1393 * 1. agent keys that are found in the config file 1394 * 2. other agent keys 1395 * 3. keys that are only listed in the config file 1396 */ 1397static void 1398pubkey_prepare(Authctxt *authctxt) 1399{ 1400 Identity *id, *id2, *tmp; 1401 Idlist agent, files, *preferred; 1402 Key *key; 1403 AuthenticationConnection *ac; 1404 char *comment; 1405 int i, found; 1406 1407 TAILQ_INIT(&agent); /* keys from the agent */ 1408 TAILQ_INIT(&files); /* keys from the config file */ 1409 preferred = &authctxt->keys; 1410 TAILQ_INIT(preferred); /* preferred order of keys */ 1411 1412 /* list of keys stored in the filesystem and PKCS#11 */ 1413 for (i = 0; i < options.num_identity_files; i++) { 1414 key = options.identity_keys[i]; 1415 if (key && key->type == KEY_RSA1) 1416 continue; 1417 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1418 continue; 1419 options.identity_keys[i] = NULL; 1420 id = xcalloc(1, sizeof(*id)); 1421 id->key = key; 1422 id->filename = xstrdup(options.identity_files[i]); 1423 id->userprovided = options.identity_file_userprovided[i]; 1424 TAILQ_INSERT_TAIL(&files, id, next); 1425 } 1426 /* Prefer PKCS11 keys that are explicitly listed */ 1427 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1428 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0) 1429 continue; 1430 found = 0; 1431 TAILQ_FOREACH(id2, &files, next) { 1432 if (id2->key == NULL || 1433 (id2->key->flags & KEY_FLAG_EXT) != 0) 1434 continue; 1435 if (key_equal(id->key, id2->key)) { 1436 TAILQ_REMOVE(&files, id, next); 1437 TAILQ_INSERT_TAIL(preferred, id, next); 1438 found = 1; 1439 break; 1440 } 1441 } 1442 /* If IdentitiesOnly set and key not found then don't use it */ 1443 if (!found && options.identities_only) { 1444 TAILQ_REMOVE(&files, id, next); 1445 bzero(id, sizeof(*id)); 1446 free(id); 1447 } 1448 } 1449 /* list of keys supported by the agent */ 1450 if ((ac = ssh_get_authentication_connection())) { 1451 for (key = ssh_get_first_identity(ac, &comment, 2); 1452 key != NULL; 1453 key = ssh_get_next_identity(ac, &comment, 2)) { 1454 found = 0; 1455 TAILQ_FOREACH(id, &files, next) { 1456 /* agent keys from the config file are preferred */ 1457 if (key_equal(key, id->key)) { 1458 key_free(key); 1459 free(comment); 1460 TAILQ_REMOVE(&files, id, next); 1461 TAILQ_INSERT_TAIL(preferred, id, next); 1462 id->ac = ac; 1463 found = 1; 1464 break; 1465 } 1466 } 1467 if (!found && !options.identities_only) { 1468 id = xcalloc(1, sizeof(*id)); 1469 id->key = key; 1470 id->filename = comment; 1471 id->ac = ac; 1472 TAILQ_INSERT_TAIL(&agent, id, next); 1473 } 1474 } 1475 /* append remaining agent keys */ 1476 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1477 TAILQ_REMOVE(&agent, id, next); 1478 TAILQ_INSERT_TAIL(preferred, id, next); 1479 } 1480 authctxt->agent = ac; 1481 } 1482 /* append remaining keys from the config file */ 1483 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1484 TAILQ_REMOVE(&files, id, next); 1485 TAILQ_INSERT_TAIL(preferred, id, next); 1486 } 1487 TAILQ_FOREACH(id, preferred, next) { 1488 debug2("key: %s (%p),%s", id->filename, id->key, 1489 id->userprovided ? " explicit" : ""); 1490 } 1491} 1492 1493static void 1494pubkey_cleanup(Authctxt *authctxt) 1495{ 1496 Identity *id; 1497 1498 if (authctxt->agent != NULL) 1499 ssh_close_authentication_connection(authctxt->agent); 1500 for (id = TAILQ_FIRST(&authctxt->keys); id; 1501 id = TAILQ_FIRST(&authctxt->keys)) { 1502 TAILQ_REMOVE(&authctxt->keys, id, next); 1503 if (id->key) 1504 key_free(id->key); 1505 free(id->filename); 1506 free(id); 1507 } 1508} 1509 1510int 1511userauth_pubkey(Authctxt *authctxt) 1512{ 1513 Identity *id; 1514 int sent = 0; 1515 1516 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1517 if (id->tried++) 1518 return (0); 1519 /* move key to the end of the queue */ 1520 TAILQ_REMOVE(&authctxt->keys, id, next); 1521 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1522 /* 1523 * send a test message if we have the public key. for 1524 * encrypted keys we cannot do this and have to load the 1525 * private key instead 1526 */ 1527 if (id->key != NULL) { 1528 if (key_type_plain(id->key->type) == KEY_RSA && 1529 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1530 debug("Skipped %s key %s for RSA/MD5 server", 1531 key_type(id->key), id->filename); 1532 } else if (id->key->type != KEY_RSA1) { 1533 debug("Offering %s public key: %s", 1534 key_type(id->key), id->filename); 1535 sent = send_pubkey_test(authctxt, id); 1536 } 1537 } else { 1538 debug("Trying private key: %s", id->filename); 1539 id->key = load_identity_file(id->filename, 1540 id->userprovided); 1541 if (id->key != NULL) { 1542 id->isprivate = 1; 1543 if (key_type_plain(id->key->type) == KEY_RSA && 1544 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1545 debug("Skipped %s key %s for RSA/MD5 " 1546 "server", key_type(id->key), 1547 id->filename); 1548 } else { 1549 sent = sign_and_send_pubkey( 1550 authctxt, id); 1551 } 1552 key_free(id->key); 1553 id->key = NULL; 1554 } 1555 } 1556 if (sent) 1557 return (sent); 1558 } 1559 return (0); 1560} 1561 1562/* 1563 * Send userauth request message specifying keyboard-interactive method. 1564 */ 1565int 1566userauth_kbdint(Authctxt *authctxt) 1567{ 1568 static int attempt = 0; 1569 1570 if (attempt++ >= options.number_of_password_prompts) 1571 return 0; 1572 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1573 if (attempt > 1 && !authctxt->info_req_seen) { 1574 debug3("userauth_kbdint: disable: no info_req_seen"); 1575 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1576 return 0; 1577 } 1578 1579 debug2("userauth_kbdint"); 1580 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1581 packet_put_cstring(authctxt->server_user); 1582 packet_put_cstring(authctxt->service); 1583 packet_put_cstring(authctxt->method->name); 1584 packet_put_cstring(""); /* lang */ 1585 packet_put_cstring(options.kbd_interactive_devices ? 1586 options.kbd_interactive_devices : ""); 1587 packet_send(); 1588 1589 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1590 return 1; 1591} 1592 1593/* 1594 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1595 */ 1596void 1597input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1598{ 1599 Authctxt *authctxt = ctxt; 1600 char *name, *inst, *lang, *prompt, *response; 1601 u_int num_prompts, i; 1602 int echo = 0; 1603 1604 debug2("input_userauth_info_req"); 1605 1606 if (authctxt == NULL) 1607 fatal("input_userauth_info_req: no authentication context"); 1608 1609 authctxt->info_req_seen = 1; 1610 1611 name = packet_get_string(NULL); 1612 inst = packet_get_string(NULL); 1613 lang = packet_get_string(NULL); 1614 if (strlen(name) > 0) 1615 logit("%s", name); 1616 if (strlen(inst) > 0) 1617 logit("%s", inst); 1618 free(name); 1619 free(inst); 1620 free(lang); 1621 1622 num_prompts = packet_get_int(); 1623 /* 1624 * Begin to build info response packet based on prompts requested. 1625 * We commit to providing the correct number of responses, so if 1626 * further on we run into a problem that prevents this, we have to 1627 * be sure and clean this up and send a correct error response. 1628 */ 1629 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1630 packet_put_int(num_prompts); 1631 1632 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1633 for (i = 0; i < num_prompts; i++) { 1634 prompt = packet_get_string(NULL); 1635 echo = packet_get_char(); 1636 1637 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1638 1639 packet_put_cstring(response); 1640 memset(response, 0, strlen(response)); 1641 free(response); 1642 free(prompt); 1643 } 1644 packet_check_eom(); /* done with parsing incoming message. */ 1645 1646 packet_add_padding(64); 1647 packet_send(); 1648} 1649 1650static int 1651ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1652 u_char *data, u_int datalen) 1653{ 1654 Buffer b; 1655 struct stat st; 1656 pid_t pid; 1657 int to[2], from[2], status, version = 2; 1658 1659 debug2("ssh_keysign called"); 1660 1661 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1662 error("ssh_keysign: not installed: %s", strerror(errno)); 1663 return -1; 1664 } 1665 if (fflush(stdout) != 0) 1666 error("ssh_keysign: fflush: %s", strerror(errno)); 1667 if (pipe(to) < 0) { 1668 error("ssh_keysign: pipe: %s", strerror(errno)); 1669 return -1; 1670 } 1671 if (pipe(from) < 0) { 1672 error("ssh_keysign: pipe: %s", strerror(errno)); 1673 return -1; 1674 } 1675 if ((pid = fork()) < 0) { 1676 error("ssh_keysign: fork: %s", strerror(errno)); 1677 return -1; 1678 } 1679 if (pid == 0) { 1680 /* keep the socket on exec */ 1681 fcntl(packet_get_connection_in(), F_SETFD, 0); 1682 permanently_drop_suid(getuid()); 1683 close(from[0]); 1684 if (dup2(from[1], STDOUT_FILENO) < 0) 1685 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1686 close(to[1]); 1687 if (dup2(to[0], STDIN_FILENO) < 0) 1688 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1689 close(from[1]); 1690 close(to[0]); 1691 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1692 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1693 strerror(errno)); 1694 } 1695 close(from[1]); 1696 close(to[0]); 1697 1698 buffer_init(&b); 1699 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1700 buffer_put_string(&b, data, datalen); 1701 if (ssh_msg_send(to[1], version, &b) == -1) 1702 fatal("ssh_keysign: couldn't send request"); 1703 1704 if (ssh_msg_recv(from[0], &b) < 0) { 1705 error("ssh_keysign: no reply"); 1706 buffer_free(&b); 1707 return -1; 1708 } 1709 close(from[0]); 1710 close(to[1]); 1711 1712 while (waitpid(pid, &status, 0) < 0) 1713 if (errno != EINTR) 1714 break; 1715 1716 if (buffer_get_char(&b) != version) { 1717 error("ssh_keysign: bad version"); 1718 buffer_free(&b); 1719 return -1; 1720 } 1721 *sigp = buffer_get_string(&b, lenp); 1722 buffer_free(&b); 1723 1724 return 0; 1725} 1726 1727int 1728userauth_hostbased(Authctxt *authctxt) 1729{ 1730 Key *private = NULL; 1731 Sensitive *sensitive = authctxt->sensitive; 1732 Buffer b; 1733 u_char *signature, *blob; 1734 char *chost, *pkalg, *p; 1735 const char *service; 1736 u_int blen, slen; 1737 int ok, i, found = 0; 1738 1739 /* check for a useful key */ 1740 for (i = 0; i < sensitive->nkeys; i++) { 1741 private = sensitive->keys[i]; 1742 if (private && private->type != KEY_RSA1) { 1743 found = 1; 1744 /* we take and free the key */ 1745 sensitive->keys[i] = NULL; 1746 break; 1747 } 1748 } 1749 if (!found) { 1750 debug("No more client hostkeys for hostbased authentication."); 1751 return 0; 1752 } 1753 if (key_to_blob(private, &blob, &blen) == 0) { 1754 key_free(private); 1755 return 0; 1756 } 1757 /* figure out a name for the client host */ 1758 p = get_local_name(packet_get_connection_in()); 1759 if (p == NULL) { 1760 error("userauth_hostbased: cannot get local ipaddr/name"); 1761 key_free(private); 1762 free(blob); 1763 return 0; 1764 } 1765 xasprintf(&chost, "%s.", p); 1766 debug2("userauth_hostbased: chost %s", chost); 1767 free(p); 1768 1769 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1770 authctxt->service; 1771 pkalg = xstrdup(key_ssh_name(private)); 1772 buffer_init(&b); 1773 /* construct data */ 1774 buffer_put_string(&b, session_id2, session_id2_len); 1775 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1776 buffer_put_cstring(&b, authctxt->server_user); 1777 buffer_put_cstring(&b, service); 1778 buffer_put_cstring(&b, authctxt->method->name); 1779 buffer_put_cstring(&b, pkalg); 1780 buffer_put_string(&b, blob, blen); 1781 buffer_put_cstring(&b, chost); 1782 buffer_put_cstring(&b, authctxt->local_user); 1783#ifdef DEBUG_PK 1784 buffer_dump(&b); 1785#endif 1786 if (sensitive->external_keysign) 1787 ok = ssh_keysign(private, &signature, &slen, 1788 buffer_ptr(&b), buffer_len(&b)); 1789 else 1790 ok = key_sign(private, &signature, &slen, 1791 buffer_ptr(&b), buffer_len(&b)); 1792 key_free(private); 1793 buffer_free(&b); 1794 if (ok != 0) { 1795 error("key_sign failed"); 1796 free(chost); 1797 free(pkalg); 1798 free(blob); 1799 return 0; 1800 } 1801 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1802 packet_put_cstring(authctxt->server_user); 1803 packet_put_cstring(authctxt->service); 1804 packet_put_cstring(authctxt->method->name); 1805 packet_put_cstring(pkalg); 1806 packet_put_string(blob, blen); 1807 packet_put_cstring(chost); 1808 packet_put_cstring(authctxt->local_user); 1809 packet_put_string(signature, slen); 1810 memset(signature, 's', slen); 1811 free(signature); 1812 free(chost); 1813 free(pkalg); 1814 free(blob); 1815 1816 packet_send(); 1817 return 1; 1818} 1819 1820#ifdef JPAKE 1821int 1822userauth_jpake(Authctxt *authctxt) 1823{ 1824 struct jpake_ctx *pctx; 1825 u_char *x1_proof, *x2_proof; 1826 u_int x1_proof_len, x2_proof_len; 1827 static int attempt = 0; /* XXX share with userauth_password's? */ 1828 1829 if (attempt++ >= options.number_of_password_prompts) 1830 return 0; 1831 if (attempt != 1) 1832 error("Permission denied, please try again."); 1833 1834 if (authctxt->methoddata != NULL) 1835 fatal("%s: authctxt->methoddata already set (%p)", 1836 __func__, authctxt->methoddata); 1837 1838 authctxt->methoddata = pctx = jpake_new(); 1839 1840 /* 1841 * Send request immediately, to get the protocol going while 1842 * we do the initial computations. 1843 */ 1844 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1845 packet_put_cstring(authctxt->server_user); 1846 packet_put_cstring(authctxt->service); 1847 packet_put_cstring(authctxt->method->name); 1848 packet_send(); 1849 packet_write_wait(); 1850 1851 jpake_step1(pctx->grp, 1852 &pctx->client_id, &pctx->client_id_len, 1853 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1854 &x1_proof, &x1_proof_len, 1855 &x2_proof, &x2_proof_len); 1856 1857 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1858 1859 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1860 packet_put_string(pctx->client_id, pctx->client_id_len); 1861 packet_put_bignum2(pctx->g_x1); 1862 packet_put_bignum2(pctx->g_x2); 1863 packet_put_string(x1_proof, x1_proof_len); 1864 packet_put_string(x2_proof, x2_proof_len); 1865 packet_send(); 1866 1867 bzero(x1_proof, x1_proof_len); 1868 bzero(x2_proof, x2_proof_len); 1869 free(x1_proof); 1870 free(x2_proof); 1871 1872 /* Expect step 1 packet from peer */ 1873 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1874 input_userauth_jpake_server_step1); 1875 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1876 &input_userauth_success_unexpected); 1877 1878 return 1; 1879} 1880 1881void 1882userauth_jpake_cleanup(Authctxt *authctxt) 1883{ 1884 debug3("%s: clean up", __func__); 1885 if (authctxt->methoddata != NULL) { 1886 jpake_free(authctxt->methoddata); 1887 authctxt->methoddata = NULL; 1888 } 1889 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1890} 1891#endif /* JPAKE */ 1892 1893/* find auth method */ 1894 1895/* 1896 * given auth method name, if configurable options permit this method fill 1897 * in auth_ident field and return true, otherwise return false. 1898 */ 1899static int 1900authmethod_is_enabled(Authmethod *method) 1901{ 1902 if (method == NULL) 1903 return 0; 1904 /* return false if options indicate this method is disabled */ 1905 if (method->enabled == NULL || *method->enabled == 0) 1906 return 0; 1907 /* return false if batch mode is enabled but method needs interactive mode */ 1908 if (method->batch_flag != NULL && *method->batch_flag != 0) 1909 return 0; 1910 return 1; 1911} 1912 1913static Authmethod * 1914authmethod_lookup(const char *name) 1915{ 1916 Authmethod *method = NULL; 1917 if (name != NULL) 1918 for (method = authmethods; method->name != NULL; method++) 1919 if (strcmp(name, method->name) == 0) 1920 return method; 1921 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1922 return NULL; 1923} 1924 1925/* XXX internal state */ 1926static Authmethod *current = NULL; 1927static char *supported = NULL; 1928static char *preferred = NULL; 1929 1930/* 1931 * Given the authentication method list sent by the server, return the 1932 * next method we should try. If the server initially sends a nil list, 1933 * use a built-in default list. 1934 */ 1935static Authmethod * 1936authmethod_get(char *authlist) 1937{ 1938 char *name = NULL; 1939 u_int next; 1940 1941 /* Use a suitable default if we're passed a nil list. */ 1942 if (authlist == NULL || strlen(authlist) == 0) 1943 authlist = options.preferred_authentications; 1944 1945 if (supported == NULL || strcmp(authlist, supported) != 0) { 1946 debug3("start over, passed a different list %s", authlist); 1947 free(supported); 1948 supported = xstrdup(authlist); 1949 preferred = options.preferred_authentications; 1950 debug3("preferred %s", preferred); 1951 current = NULL; 1952 } else if (current != NULL && authmethod_is_enabled(current)) 1953 return current; 1954 1955 for (;;) { 1956 if ((name = match_list(preferred, supported, &next)) == NULL) { 1957 debug("No more authentication methods to try."); 1958 current = NULL; 1959 return NULL; 1960 } 1961 preferred += next; 1962 debug3("authmethod_lookup %s", name); 1963 debug3("remaining preferred: %s", preferred); 1964 if ((current = authmethod_lookup(name)) != NULL && 1965 authmethod_is_enabled(current)) { 1966 debug3("authmethod_is_enabled %s", name); 1967 debug("Next authentication method: %s", name); 1968 free(name); 1969 return current; 1970 } 1971 free(name); 1972 } 1973} 1974 1975static char * 1976authmethods_get(void) 1977{ 1978 Authmethod *method = NULL; 1979 Buffer b; 1980 char *list; 1981 1982 buffer_init(&b); 1983 for (method = authmethods; method->name != NULL; method++) { 1984 if (authmethod_is_enabled(method)) { 1985 if (buffer_len(&b) > 0) 1986 buffer_append(&b, ",", 1); 1987 buffer_append(&b, method->name, strlen(method->name)); 1988 } 1989 } 1990 buffer_append(&b, "\0", 1); 1991 list = xstrdup(buffer_ptr(&b)); 1992 buffer_free(&b); 1993 return list; 1994} 1995 1996