sshconnect2.c revision 263691
1/* $OpenBSD: sshconnect2.c,v 1.201 2014/01/09 23:20:00 djm Exp $ */ 2/* $FreeBSD: head/crypto/openssh/sshconnect2.c 263691 2014-03-24 19:15:13Z 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__RCSID("$FreeBSD: head/crypto/openssh/sshconnect2.c 263691 2014-03-24 19:15:13Z des $"); 30 31#include <sys/types.h> 32#include <sys/socket.h> 33#include <sys/wait.h> 34#include <sys/stat.h> 35 36#include <errno.h> 37#include <fcntl.h> 38#include <netdb.h> 39#include <pwd.h> 40#include <signal.h> 41#include <stdarg.h> 42#include <stdio.h> 43#include <string.h> 44#include <unistd.h> 45#if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 46#include <vis.h> 47#endif 48 49#include "openbsd-compat/sys-queue.h" 50 51#include "xmalloc.h" 52#include "ssh.h" 53#include "ssh2.h" 54#include "buffer.h" 55#include "packet.h" 56#include "compat.h" 57#include "cipher.h" 58#include "key.h" 59#include "kex.h" 60#include "myproposal.h" 61#include "sshconnect.h" 62#include "authfile.h" 63#include "dh.h" 64#include "authfd.h" 65#include "log.h" 66#include "readconf.h" 67#include "misc.h" 68#include "match.h" 69#include "dispatch.h" 70#include "canohost.h" 71#include "msg.h" 72#include "pathnames.h" 73#include "uidswap.h" 74#include "hostfile.h" 75#include "schnorr.h" 76#include "jpake.h" 77 78#ifdef GSSAPI 79#include "ssh-gss.h" 80#endif 81 82/* import */ 83extern char *client_version_string; 84extern char *server_version_string; 85extern Options options; 86#ifdef NONE_CIPHER_ENABLED 87extern Kex *xxx_kex; 88 89/* 90 * tty_flag is set in ssh.c so we can use it here. If set then prevent 91 * the switch to the null cipher. 92 */ 93 94extern int tty_flag; 95#endif 96 97/* 98 * SSH2 key exchange 99 */ 100 101u_char *session_id2 = NULL; 102u_int session_id2_len = 0; 103 104char *xxx_host; 105struct sockaddr *xxx_hostaddr; 106 107Kex *xxx_kex = NULL; 108 109static int 110verify_host_key_callback(Key *hostkey) 111{ 112 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 113 fatal("Host key verification failed."); 114 return 0; 115} 116 117static char * 118order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 119{ 120 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 121 size_t maxlen; 122 struct hostkeys *hostkeys; 123 int ktype; 124 u_int i; 125 126 /* Find all hostkeys for this hostname */ 127 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 128 hostkeys = init_hostkeys(); 129 for (i = 0; i < options.num_user_hostfiles; i++) 130 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 131 for (i = 0; i < options.num_system_hostfiles; i++) 132 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 133 134 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 135 maxlen = strlen(avail) + 1; 136 first = xmalloc(maxlen); 137 last = xmalloc(maxlen); 138 *first = *last = '\0'; 139 140#define ALG_APPEND(to, from) \ 141 do { \ 142 if (*to != '\0') \ 143 strlcat(to, ",", maxlen); \ 144 strlcat(to, from, maxlen); \ 145 } while (0) 146 147 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 148 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 149 fatal("%s: unknown alg %s", __func__, alg); 150 if (lookup_key_in_hostkeys_by_type(hostkeys, 151 key_type_plain(ktype), NULL)) 152 ALG_APPEND(first, alg); 153 else 154 ALG_APPEND(last, alg); 155 } 156#undef ALG_APPEND 157 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 158 if (*first != '\0') 159 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 160 161 free(first); 162 free(last); 163 free(hostname); 164 free(oavail); 165 free_hostkeys(hostkeys); 166 167 return ret; 168} 169 170void 171ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 172{ 173 Kex *kex; 174 175 xxx_host = host; 176 xxx_hostaddr = hostaddr; 177 178 if (options.ciphers == (char *)-1) { 179 logit("No valid ciphers for protocol version 2 given, using defaults."); 180 options.ciphers = NULL; 181 } 182 if (options.ciphers != NULL) { 183 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 184 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 185 } 186 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 187 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 188 myproposal[PROPOSAL_ENC_ALGS_STOC] = 189 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 190 if (options.compression) { 191 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 192 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 193 } else { 194 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 195 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 196 } 197 if (options.macs != NULL) { 198 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 199 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 200 } 201 if (options.hostkeyalgorithms != NULL) 202 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 203 compat_pkalg_proposal(options.hostkeyalgorithms); 204 else { 205 /* Prefer algorithms that we already have keys for */ 206 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 207 compat_pkalg_proposal( 208 order_hostkeyalgs(host, hostaddr, port)); 209 } 210 if (options.kex_algorithms != NULL) 211 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 212 213 if (options.rekey_limit || options.rekey_interval) 214 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 215 (time_t)options.rekey_interval); 216 217 /* start key exchange */ 218 kex = kex_setup(myproposal); 219 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 220 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 221 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 222 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 223 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 224 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 225 kex->client_version_string=client_version_string; 226 kex->server_version_string=server_version_string; 227 kex->verify_host_key=&verify_host_key_callback; 228 229 xxx_kex = kex; 230 231 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 232 233 if (options.use_roaming && !kex->roaming) { 234 debug("Roaming not allowed by server"); 235 options.use_roaming = 0; 236 } 237 238 session_id2 = kex->session_id; 239 session_id2_len = kex->session_id_len; 240 241#ifdef DEBUG_KEXDH 242 /* send 1st encrypted/maced/compressed message */ 243 packet_start(SSH2_MSG_IGNORE); 244 packet_put_cstring("markus"); 245 packet_send(); 246 packet_write_wait(); 247#endif 248} 249 250/* 251 * Authenticate user 252 */ 253 254typedef struct Authctxt Authctxt; 255typedef struct Authmethod Authmethod; 256typedef struct identity Identity; 257typedef struct idlist Idlist; 258 259struct identity { 260 TAILQ_ENTRY(identity) next; 261 AuthenticationConnection *ac; /* set if agent supports key */ 262 Key *key; /* public/private key */ 263 char *filename; /* comment for agent-only keys */ 264 int tried; 265 int isprivate; /* key points to the private key */ 266 int userprovided; 267}; 268TAILQ_HEAD(idlist, identity); 269 270struct Authctxt { 271 const char *server_user; 272 const char *local_user; 273 const char *host; 274 const char *service; 275 Authmethod *method; 276 sig_atomic_t success; 277 char *authlist; 278 /* pubkey */ 279 Idlist keys; 280 AuthenticationConnection *agent; 281 /* hostbased */ 282 Sensitive *sensitive; 283 /* kbd-interactive */ 284 int info_req_seen; 285 /* generic */ 286 void *methoddata; 287}; 288struct Authmethod { 289 char *name; /* string to compare against server's list */ 290 int (*userauth)(Authctxt *authctxt); 291 void (*cleanup)(Authctxt *authctxt); 292 int *enabled; /* flag in option struct that enables method */ 293 int *batch_flag; /* flag in option struct that disables method */ 294}; 295 296void input_userauth_success(int, u_int32_t, void *); 297void input_userauth_success_unexpected(int, u_int32_t, void *); 298void input_userauth_failure(int, u_int32_t, void *); 299void input_userauth_banner(int, u_int32_t, void *); 300void input_userauth_error(int, u_int32_t, void *); 301void input_userauth_info_req(int, u_int32_t, void *); 302void input_userauth_pk_ok(int, u_int32_t, void *); 303void input_userauth_passwd_changereq(int, u_int32_t, void *); 304void input_userauth_jpake_server_step1(int, u_int32_t, void *); 305void input_userauth_jpake_server_step2(int, u_int32_t, void *); 306void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 307 308int userauth_none(Authctxt *); 309int userauth_pubkey(Authctxt *); 310int userauth_passwd(Authctxt *); 311int userauth_kbdint(Authctxt *); 312int userauth_hostbased(Authctxt *); 313int userauth_jpake(Authctxt *); 314 315void userauth_jpake_cleanup(Authctxt *); 316 317#ifdef GSSAPI 318int userauth_gssapi(Authctxt *authctxt); 319void input_gssapi_response(int type, u_int32_t, void *); 320void input_gssapi_token(int type, u_int32_t, void *); 321void input_gssapi_hash(int type, u_int32_t, void *); 322void input_gssapi_error(int, u_int32_t, void *); 323void input_gssapi_errtok(int, u_int32_t, void *); 324#endif 325 326void userauth(Authctxt *, char *); 327 328static int sign_and_send_pubkey(Authctxt *, Identity *); 329static void pubkey_prepare(Authctxt *); 330static void pubkey_cleanup(Authctxt *); 331static Key *load_identity_file(char *, int); 332 333static Authmethod *authmethod_get(char *authlist); 334static Authmethod *authmethod_lookup(const char *name); 335static char *authmethods_get(void); 336 337Authmethod authmethods[] = { 338#ifdef GSSAPI 339 {"gssapi-with-mic", 340 userauth_gssapi, 341 NULL, 342 &options.gss_authentication, 343 NULL}, 344#endif 345 {"hostbased", 346 userauth_hostbased, 347 NULL, 348 &options.hostbased_authentication, 349 NULL}, 350 {"publickey", 351 userauth_pubkey, 352 NULL, 353 &options.pubkey_authentication, 354 NULL}, 355#ifdef JPAKE 356 {"jpake-01@openssh.com", 357 userauth_jpake, 358 userauth_jpake_cleanup, 359 &options.zero_knowledge_password_authentication, 360 &options.batch_mode}, 361#endif 362 {"keyboard-interactive", 363 userauth_kbdint, 364 NULL, 365 &options.kbd_interactive_authentication, 366 &options.batch_mode}, 367 {"password", 368 userauth_passwd, 369 NULL, 370 &options.password_authentication, 371 &options.batch_mode}, 372 {"none", 373 userauth_none, 374 NULL, 375 NULL, 376 NULL}, 377 {NULL, NULL, NULL, NULL, NULL} 378}; 379 380void 381ssh_userauth2(const char *local_user, const char *server_user, char *host, 382 Sensitive *sensitive) 383{ 384 Authctxt authctxt; 385 int type; 386 387 if (options.challenge_response_authentication) 388 options.kbd_interactive_authentication = 1; 389 390 packet_start(SSH2_MSG_SERVICE_REQUEST); 391 packet_put_cstring("ssh-userauth"); 392 packet_send(); 393 debug("SSH2_MSG_SERVICE_REQUEST sent"); 394 packet_write_wait(); 395 type = packet_read(); 396 if (type != SSH2_MSG_SERVICE_ACCEPT) 397 fatal("Server denied authentication request: %d", type); 398 if (packet_remaining() > 0) { 399 char *reply = packet_get_string(NULL); 400 debug2("service_accept: %s", reply); 401 free(reply); 402 } else { 403 debug2("buggy server: service_accept w/o service"); 404 } 405 packet_check_eom(); 406 debug("SSH2_MSG_SERVICE_ACCEPT received"); 407 408 if (options.preferred_authentications == NULL) 409 options.preferred_authentications = authmethods_get(); 410 411 /* setup authentication context */ 412 memset(&authctxt, 0, sizeof(authctxt)); 413 pubkey_prepare(&authctxt); 414 authctxt.server_user = server_user; 415 authctxt.local_user = local_user; 416 authctxt.host = host; 417 authctxt.service = "ssh-connection"; /* service name */ 418 authctxt.success = 0; 419 authctxt.method = authmethod_lookup("none"); 420 authctxt.authlist = NULL; 421 authctxt.methoddata = NULL; 422 authctxt.sensitive = sensitive; 423 authctxt.info_req_seen = 0; 424 if (authctxt.method == NULL) 425 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 426 427 /* initial userauth request */ 428 userauth_none(&authctxt); 429 430 dispatch_init(&input_userauth_error); 431 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 432 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 433 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 434 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 435 436 pubkey_cleanup(&authctxt); 437 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 438 439#ifdef NONE_CIPHER_ENABLED 440 /* 441 * If the user explicitly requests to use the none cipher enable it 442 * post authentication and only if the right conditions are met: both 443 * of the NONE switches must be true and there must be no tty allocated. 444 */ 445 if (options.none_switch == 1 && options.none_enabled == 1) { 446 if (!tty_flag) { 447 debug("Requesting none cipher re-keying..."); 448 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 449 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 450 kex_prop2buf(&xxx_kex->my, myproposal); 451 packet_request_rekeying(); 452 fprintf(stderr, "WARNING: enabled NONE cipher\n"); 453 } else { 454 /* Requested NONE cipher on an interactive session. */ 455 debug("Cannot switch to NONE cipher with tty " 456 "allocated"); 457 fprintf(stderr, "NONE cipher switch disabled given " 458 "a TTY is allocated\n"); 459 } 460 } 461#endif 462 debug("Authentication succeeded (%s).", authctxt.method->name); 463} 464 465void 466userauth(Authctxt *authctxt, char *authlist) 467{ 468 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 469 authctxt->method->cleanup(authctxt); 470 471 free(authctxt->methoddata); 472 authctxt->methoddata = NULL; 473 if (authlist == NULL) { 474 authlist = authctxt->authlist; 475 } else { 476 free(authctxt->authlist); 477 authctxt->authlist = authlist; 478 } 479 for (;;) { 480 Authmethod *method = authmethod_get(authlist); 481 if (method == NULL) 482 fatal("Permission denied (%s).", authlist); 483 authctxt->method = method; 484 485 /* reset the per method handler */ 486 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 487 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 488 489 /* and try new method */ 490 if (method->userauth(authctxt) != 0) { 491 debug2("we sent a %s packet, wait for reply", method->name); 492 break; 493 } else { 494 debug2("we did not send a packet, disable method"); 495 method->enabled = NULL; 496 } 497 } 498} 499 500/* ARGSUSED */ 501void 502input_userauth_error(int type, u_int32_t seq, void *ctxt) 503{ 504 fatal("input_userauth_error: bad message during authentication: " 505 "type %d", type); 506} 507 508/* ARGSUSED */ 509void 510input_userauth_banner(int type, u_int32_t seq, void *ctxt) 511{ 512 char *msg, *raw, *lang; 513 u_int len; 514 515 debug3("input_userauth_banner"); 516 raw = packet_get_string(&len); 517 lang = packet_get_string(NULL); 518 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 519 if (len > 65536) 520 len = 65536; 521 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 522 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 523 fprintf(stderr, "%s", msg); 524 free(msg); 525 } 526 free(raw); 527 free(lang); 528} 529 530/* ARGSUSED */ 531void 532input_userauth_success(int type, u_int32_t seq, void *ctxt) 533{ 534 Authctxt *authctxt = ctxt; 535 536 if (authctxt == NULL) 537 fatal("input_userauth_success: no authentication context"); 538 free(authctxt->authlist); 539 authctxt->authlist = NULL; 540 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 541 authctxt->method->cleanup(authctxt); 542 free(authctxt->methoddata); 543 authctxt->methoddata = NULL; 544 authctxt->success = 1; /* break out */ 545} 546 547void 548input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 549{ 550 Authctxt *authctxt = ctxt; 551 552 if (authctxt == NULL) 553 fatal("%s: no authentication context", __func__); 554 555 fatal("Unexpected authentication success during %s.", 556 authctxt->method->name); 557} 558 559/* ARGSUSED */ 560void 561input_userauth_failure(int type, u_int32_t seq, void *ctxt) 562{ 563 Authctxt *authctxt = ctxt; 564 char *authlist = NULL; 565 int partial; 566 567 if (authctxt == NULL) 568 fatal("input_userauth_failure: no authentication context"); 569 570 authlist = packet_get_string(NULL); 571 partial = packet_get_char(); 572 packet_check_eom(); 573 574 if (partial != 0) { 575 logit("Authenticated with partial success."); 576 /* reset state */ 577 pubkey_cleanup(authctxt); 578 pubkey_prepare(authctxt); 579 } 580 debug("Authentications that can continue: %s", authlist); 581 582 userauth(authctxt, authlist); 583} 584 585/* ARGSUSED */ 586void 587input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 588{ 589 Authctxt *authctxt = ctxt; 590 Key *key = NULL; 591 Identity *id = NULL; 592 Buffer b; 593 int pktype, sent = 0; 594 u_int alen, blen; 595 char *pkalg, *fp; 596 u_char *pkblob; 597 598 if (authctxt == NULL) 599 fatal("input_userauth_pk_ok: no authentication context"); 600 if (datafellows & SSH_BUG_PKOK) { 601 /* this is similar to SSH_BUG_PKAUTH */ 602 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 603 pkblob = packet_get_string(&blen); 604 buffer_init(&b); 605 buffer_append(&b, pkblob, blen); 606 pkalg = buffer_get_string(&b, &alen); 607 buffer_free(&b); 608 } else { 609 pkalg = packet_get_string(&alen); 610 pkblob = packet_get_string(&blen); 611 } 612 packet_check_eom(); 613 614 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 615 616 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 617 debug("unknown pkalg %s", pkalg); 618 goto done; 619 } 620 if ((key = key_from_blob(pkblob, blen)) == NULL) { 621 debug("no key from blob. pkalg %s", pkalg); 622 goto done; 623 } 624 if (key->type != pktype) { 625 error("input_userauth_pk_ok: type mismatch " 626 "for decoded key (received %d, expected %d)", 627 key->type, pktype); 628 goto done; 629 } 630 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 631 debug2("input_userauth_pk_ok: fp %s", fp); 632 free(fp); 633 634 /* 635 * search keys in the reverse order, because last candidate has been 636 * moved to the end of the queue. this also avoids confusion by 637 * duplicate keys 638 */ 639 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 640 if (key_equal(key, id->key)) { 641 sent = sign_and_send_pubkey(authctxt, id); 642 break; 643 } 644 } 645done: 646 if (key != NULL) 647 key_free(key); 648 free(pkalg); 649 free(pkblob); 650 651 /* try another method if we did not send a packet */ 652 if (sent == 0) 653 userauth(authctxt, NULL); 654} 655 656#ifdef GSSAPI 657int 658userauth_gssapi(Authctxt *authctxt) 659{ 660 Gssctxt *gssctxt = NULL; 661 static gss_OID_set gss_supported = NULL; 662 static u_int mech = 0; 663 OM_uint32 min; 664 int ok = 0; 665 666 /* Try one GSSAPI method at a time, rather than sending them all at 667 * once. */ 668 669 if (gss_supported == NULL) 670 gss_indicate_mechs(&min, &gss_supported); 671 672 /* Check to see if the mechanism is usable before we offer it */ 673 while (mech < gss_supported->count && !ok) { 674 /* My DER encoding requires length<128 */ 675 if (gss_supported->elements[mech].length < 128 && 676 ssh_gssapi_check_mechanism(&gssctxt, 677 &gss_supported->elements[mech], authctxt->host)) { 678 ok = 1; /* Mechanism works */ 679 } else { 680 mech++; 681 } 682 } 683 684 if (!ok) 685 return 0; 686 687 authctxt->methoddata=(void *)gssctxt; 688 689 packet_start(SSH2_MSG_USERAUTH_REQUEST); 690 packet_put_cstring(authctxt->server_user); 691 packet_put_cstring(authctxt->service); 692 packet_put_cstring(authctxt->method->name); 693 694 packet_put_int(1); 695 696 packet_put_int((gss_supported->elements[mech].length) + 2); 697 packet_put_char(SSH_GSS_OIDTYPE); 698 packet_put_char(gss_supported->elements[mech].length); 699 packet_put_raw(gss_supported->elements[mech].elements, 700 gss_supported->elements[mech].length); 701 702 packet_send(); 703 704 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 705 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 706 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 707 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 708 709 mech++; /* Move along to next candidate */ 710 711 return 1; 712} 713 714static OM_uint32 715process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 716{ 717 Authctxt *authctxt = ctxt; 718 Gssctxt *gssctxt = authctxt->methoddata; 719 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 720 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 721 gss_buffer_desc gssbuf; 722 OM_uint32 status, ms, flags; 723 Buffer b; 724 725 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 726 recv_tok, &send_tok, &flags); 727 728 if (send_tok.length > 0) { 729 if (GSS_ERROR(status)) 730 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 731 else 732 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 733 734 packet_put_string(send_tok.value, send_tok.length); 735 packet_send(); 736 gss_release_buffer(&ms, &send_tok); 737 } 738 739 if (status == GSS_S_COMPLETE) { 740 /* send either complete or MIC, depending on mechanism */ 741 if (!(flags & GSS_C_INTEG_FLAG)) { 742 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 743 packet_send(); 744 } else { 745 ssh_gssapi_buildmic(&b, authctxt->server_user, 746 authctxt->service, "gssapi-with-mic"); 747 748 gssbuf.value = buffer_ptr(&b); 749 gssbuf.length = buffer_len(&b); 750 751 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 752 753 if (!GSS_ERROR(status)) { 754 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 755 packet_put_string(mic.value, mic.length); 756 757 packet_send(); 758 } 759 760 buffer_free(&b); 761 gss_release_buffer(&ms, &mic); 762 } 763 } 764 765 return status; 766} 767 768/* ARGSUSED */ 769void 770input_gssapi_response(int type, u_int32_t plen, void *ctxt) 771{ 772 Authctxt *authctxt = ctxt; 773 Gssctxt *gssctxt; 774 int oidlen; 775 char *oidv; 776 777 if (authctxt == NULL) 778 fatal("input_gssapi_response: no authentication context"); 779 gssctxt = authctxt->methoddata; 780 781 /* Setup our OID */ 782 oidv = packet_get_string(&oidlen); 783 784 if (oidlen <= 2 || 785 oidv[0] != SSH_GSS_OIDTYPE || 786 oidv[1] != oidlen - 2) { 787 free(oidv); 788 debug("Badly encoded mechanism OID received"); 789 userauth(authctxt, NULL); 790 return; 791 } 792 793 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 794 fatal("Server returned different OID than expected"); 795 796 packet_check_eom(); 797 798 free(oidv); 799 800 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 801 /* Start again with next method on list */ 802 debug("Trying to start again"); 803 userauth(authctxt, NULL); 804 return; 805 } 806} 807 808/* ARGSUSED */ 809void 810input_gssapi_token(int type, u_int32_t plen, void *ctxt) 811{ 812 Authctxt *authctxt = ctxt; 813 gss_buffer_desc recv_tok; 814 OM_uint32 status; 815 u_int slen; 816 817 if (authctxt == NULL) 818 fatal("input_gssapi_response: no authentication context"); 819 820 recv_tok.value = packet_get_string(&slen); 821 recv_tok.length = slen; /* safe typecast */ 822 823 packet_check_eom(); 824 825 status = process_gssapi_token(ctxt, &recv_tok); 826 827 free(recv_tok.value); 828 829 if (GSS_ERROR(status)) { 830 /* Start again with the next method in the list */ 831 userauth(authctxt, NULL); 832 return; 833 } 834} 835 836/* ARGSUSED */ 837void 838input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 839{ 840 Authctxt *authctxt = ctxt; 841 Gssctxt *gssctxt; 842 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 843 gss_buffer_desc recv_tok; 844 OM_uint32 ms; 845 u_int len; 846 847 if (authctxt == NULL) 848 fatal("input_gssapi_response: no authentication context"); 849 gssctxt = authctxt->methoddata; 850 851 recv_tok.value = packet_get_string(&len); 852 recv_tok.length = len; 853 854 packet_check_eom(); 855 856 /* Stick it into GSSAPI and see what it says */ 857 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 858 &recv_tok, &send_tok, NULL); 859 860 free(recv_tok.value); 861 gss_release_buffer(&ms, &send_tok); 862 863 /* Server will be returning a failed packet after this one */ 864} 865 866/* ARGSUSED */ 867void 868input_gssapi_error(int type, u_int32_t plen, void *ctxt) 869{ 870 char *msg; 871 char *lang; 872 873 /* maj */(void)packet_get_int(); 874 /* min */(void)packet_get_int(); 875 msg=packet_get_string(NULL); 876 lang=packet_get_string(NULL); 877 878 packet_check_eom(); 879 880 debug("Server GSSAPI Error:\n%s", msg); 881 free(msg); 882 free(lang); 883} 884#endif /* GSSAPI */ 885 886int 887userauth_none(Authctxt *authctxt) 888{ 889 /* initial userauth request */ 890 packet_start(SSH2_MSG_USERAUTH_REQUEST); 891 packet_put_cstring(authctxt->server_user); 892 packet_put_cstring(authctxt->service); 893 packet_put_cstring(authctxt->method->name); 894 packet_send(); 895 return 1; 896} 897 898int 899userauth_passwd(Authctxt *authctxt) 900{ 901 static int attempt = 0; 902 char prompt[150]; 903 char *password; 904 const char *host = options.host_key_alias ? options.host_key_alias : 905 authctxt->host; 906 907 if (attempt++ >= options.number_of_password_prompts) 908 return 0; 909 910 if (attempt != 1) 911 error("Permission denied, please try again."); 912 913 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 914 authctxt->server_user, host); 915 password = read_passphrase(prompt, 0); 916 packet_start(SSH2_MSG_USERAUTH_REQUEST); 917 packet_put_cstring(authctxt->server_user); 918 packet_put_cstring(authctxt->service); 919 packet_put_cstring(authctxt->method->name); 920 packet_put_char(0); 921 packet_put_cstring(password); 922 memset(password, 0, strlen(password)); 923 free(password); 924 packet_add_padding(64); 925 packet_send(); 926 927 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 928 &input_userauth_passwd_changereq); 929 930 return 1; 931} 932 933/* 934 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 935 */ 936/* ARGSUSED */ 937void 938input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 939{ 940 Authctxt *authctxt = ctxt; 941 char *info, *lang, *password = NULL, *retype = NULL; 942 char prompt[150]; 943 const char *host = options.host_key_alias ? options.host_key_alias : 944 authctxt->host; 945 946 debug2("input_userauth_passwd_changereq"); 947 948 if (authctxt == NULL) 949 fatal("input_userauth_passwd_changereq: " 950 "no authentication context"); 951 952 info = packet_get_string(NULL); 953 lang = packet_get_string(NULL); 954 if (strlen(info) > 0) 955 logit("%s", info); 956 free(info); 957 free(lang); 958 packet_start(SSH2_MSG_USERAUTH_REQUEST); 959 packet_put_cstring(authctxt->server_user); 960 packet_put_cstring(authctxt->service); 961 packet_put_cstring(authctxt->method->name); 962 packet_put_char(1); /* additional info */ 963 snprintf(prompt, sizeof(prompt), 964 "Enter %.30s@%.128s's old password: ", 965 authctxt->server_user, host); 966 password = read_passphrase(prompt, 0); 967 packet_put_cstring(password); 968 memset(password, 0, strlen(password)); 969 free(password); 970 password = NULL; 971 while (password == NULL) { 972 snprintf(prompt, sizeof(prompt), 973 "Enter %.30s@%.128s's new password: ", 974 authctxt->server_user, host); 975 password = read_passphrase(prompt, RP_ALLOW_EOF); 976 if (password == NULL) { 977 /* bail out */ 978 return; 979 } 980 snprintf(prompt, sizeof(prompt), 981 "Retype %.30s@%.128s's new password: ", 982 authctxt->server_user, host); 983 retype = read_passphrase(prompt, 0); 984 if (strcmp(password, retype) != 0) { 985 memset(password, 0, strlen(password)); 986 free(password); 987 logit("Mismatch; try again, EOF to quit."); 988 password = NULL; 989 } 990 memset(retype, 0, strlen(retype)); 991 free(retype); 992 } 993 packet_put_cstring(password); 994 memset(password, 0, strlen(password)); 995 free(password); 996 packet_add_padding(64); 997 packet_send(); 998 999 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1000 &input_userauth_passwd_changereq); 1001} 1002 1003#ifdef JPAKE 1004static char * 1005pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 1006{ 1007 /* OpenBSD crypt(3) handles all of these */ 1008 if (strcmp(crypt_scheme, "crypt") == 0 || 1009 strcmp(crypt_scheme, "bcrypt") == 0 || 1010 strcmp(crypt_scheme, "md5crypt") == 0 || 1011 strcmp(crypt_scheme, "crypt-extended") == 0) 1012 return xstrdup(crypt(password, salt)); 1013 error("%s: unsupported password encryption scheme \"%.100s\"", 1014 __func__, crypt_scheme); 1015 return NULL; 1016} 1017 1018static BIGNUM * 1019jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 1020 const char *salt) 1021{ 1022 char prompt[256], *password, *crypted; 1023 u_char *secret; 1024 u_int secret_len; 1025 BIGNUM *ret; 1026 1027 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 1028 authctxt->server_user, authctxt->host); 1029 password = read_passphrase(prompt, 0); 1030 1031 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 1032 logit("Disabling %s authentication", authctxt->method->name); 1033 authctxt->method->enabled = NULL; 1034 /* Continue with an empty password to fail gracefully */ 1035 crypted = xstrdup(""); 1036 } 1037 1038#ifdef JPAKE_DEBUG 1039 debug3("%s: salt = %s", __func__, salt); 1040 debug3("%s: scheme = %s", __func__, crypt_scheme); 1041 debug3("%s: crypted = %s", __func__, crypted); 1042#endif 1043 1044 if (hash_buffer(crypted, strlen(crypted), SSH_DIGEST_SHA1, 1045 &secret, &secret_len) != 0) 1046 fatal("%s: hash_buffer", __func__); 1047 1048 bzero(password, strlen(password)); 1049 bzero(crypted, strlen(crypted)); 1050 free(password); 1051 free(crypted); 1052 1053 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 1054 fatal("%s: BN_bin2bn (secret)", __func__); 1055 bzero(secret, secret_len); 1056 free(secret); 1057 1058 return ret; 1059} 1060 1061/* ARGSUSED */ 1062void 1063input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 1064{ 1065 Authctxt *authctxt = ctxt; 1066 struct jpake_ctx *pctx = authctxt->methoddata; 1067 u_char *x3_proof, *x4_proof, *x2_s_proof; 1068 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1069 char *crypt_scheme, *salt; 1070 1071 /* Disable this message */ 1072 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1073 1074 if ((pctx->g_x3 = BN_new()) == NULL || 1075 (pctx->g_x4 = BN_new()) == NULL) 1076 fatal("%s: BN_new", __func__); 1077 1078 /* Fetch step 1 values */ 1079 crypt_scheme = packet_get_string(NULL); 1080 salt = packet_get_string(NULL); 1081 pctx->server_id = packet_get_string(&pctx->server_id_len); 1082 packet_get_bignum2(pctx->g_x3); 1083 packet_get_bignum2(pctx->g_x4); 1084 x3_proof = packet_get_string(&x3_proof_len); 1085 x4_proof = packet_get_string(&x4_proof_len); 1086 packet_check_eom(); 1087 1088 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1089 1090 /* Obtain password and derive secret */ 1091 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1092 bzero(crypt_scheme, strlen(crypt_scheme)); 1093 bzero(salt, strlen(salt)); 1094 free(crypt_scheme); 1095 free(salt); 1096 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1097 1098 /* Calculate step 2 values */ 1099 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1100 pctx->g_x3, pctx->g_x4, pctx->x2, 1101 pctx->server_id, pctx->server_id_len, 1102 pctx->client_id, pctx->client_id_len, 1103 x3_proof, x3_proof_len, 1104 x4_proof, x4_proof_len, 1105 &pctx->a, 1106 &x2_s_proof, &x2_s_proof_len); 1107 1108 bzero(x3_proof, x3_proof_len); 1109 bzero(x4_proof, x4_proof_len); 1110 free(x3_proof); 1111 free(x4_proof); 1112 1113 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1114 1115 /* Send values for step 2 */ 1116 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1117 packet_put_bignum2(pctx->a); 1118 packet_put_string(x2_s_proof, x2_s_proof_len); 1119 packet_send(); 1120 1121 bzero(x2_s_proof, x2_s_proof_len); 1122 free(x2_s_proof); 1123 1124 /* Expect step 2 packet from peer */ 1125 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1126 input_userauth_jpake_server_step2); 1127} 1128 1129/* ARGSUSED */ 1130void 1131input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1132{ 1133 Authctxt *authctxt = ctxt; 1134 struct jpake_ctx *pctx = authctxt->methoddata; 1135 u_char *x4_s_proof; 1136 u_int x4_s_proof_len; 1137 1138 /* Disable this message */ 1139 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1140 1141 if ((pctx->b = BN_new()) == NULL) 1142 fatal("%s: BN_new", __func__); 1143 1144 /* Fetch step 2 values */ 1145 packet_get_bignum2(pctx->b); 1146 x4_s_proof = packet_get_string(&x4_s_proof_len); 1147 packet_check_eom(); 1148 1149 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1150 1151 /* Derive shared key and calculate confirmation hash */ 1152 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1153 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1154 pctx->client_id, pctx->client_id_len, 1155 pctx->server_id, pctx->server_id_len, 1156 session_id2, session_id2_len, 1157 x4_s_proof, x4_s_proof_len, 1158 &pctx->k, 1159 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1160 1161 bzero(x4_s_proof, x4_s_proof_len); 1162 free(x4_s_proof); 1163 1164 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1165 1166 /* Send key confirmation proof */ 1167 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1168 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1169 packet_send(); 1170 1171 /* Expect confirmation from peer */ 1172 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1173 input_userauth_jpake_server_confirm); 1174} 1175 1176/* ARGSUSED */ 1177void 1178input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1179{ 1180 Authctxt *authctxt = ctxt; 1181 struct jpake_ctx *pctx = authctxt->methoddata; 1182 1183 /* Disable this message */ 1184 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1185 1186 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1187 packet_check_eom(); 1188 1189 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1190 1191 /* Verify expected confirmation hash */ 1192 if (jpake_check_confirm(pctx->k, 1193 pctx->server_id, pctx->server_id_len, 1194 session_id2, session_id2_len, 1195 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1196 debug("%s: %s success", __func__, authctxt->method->name); 1197 else { 1198 debug("%s: confirmation mismatch", __func__); 1199 /* XXX stash this so if auth succeeds then we can warn/kill */ 1200 } 1201 1202 userauth_jpake_cleanup(authctxt); 1203} 1204#endif /* JPAKE */ 1205 1206static int 1207identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1208 u_char *data, u_int datalen) 1209{ 1210 Key *prv; 1211 int ret; 1212 1213 /* the agent supports this key */ 1214 if (id->ac) 1215 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1216 data, datalen)); 1217 /* 1218 * we have already loaded the private key or 1219 * the private key is stored in external hardware 1220 */ 1221 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1222 return (key_sign(id->key, sigp, lenp, data, datalen)); 1223 /* load the private key from the file */ 1224 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 1225 return (-1); 1226 ret = key_sign(prv, sigp, lenp, data, datalen); 1227 key_free(prv); 1228 return (ret); 1229} 1230 1231static int 1232sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1233{ 1234 Buffer b; 1235 u_char *blob, *signature; 1236 u_int bloblen, slen; 1237 u_int skip = 0; 1238 int ret = -1; 1239 int have_sig = 1; 1240 char *fp; 1241 1242 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1243 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1244 free(fp); 1245 1246 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1247 /* we cannot handle this key */ 1248 debug3("sign_and_send_pubkey: cannot handle key"); 1249 return 0; 1250 } 1251 /* data to be signed */ 1252 buffer_init(&b); 1253 if (datafellows & SSH_OLD_SESSIONID) { 1254 buffer_append(&b, session_id2, session_id2_len); 1255 skip = session_id2_len; 1256 } else { 1257 buffer_put_string(&b, session_id2, session_id2_len); 1258 skip = buffer_len(&b); 1259 } 1260 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1261 buffer_put_cstring(&b, authctxt->server_user); 1262 buffer_put_cstring(&b, 1263 datafellows & SSH_BUG_PKSERVICE ? 1264 "ssh-userauth" : 1265 authctxt->service); 1266 if (datafellows & SSH_BUG_PKAUTH) { 1267 buffer_put_char(&b, have_sig); 1268 } else { 1269 buffer_put_cstring(&b, authctxt->method->name); 1270 buffer_put_char(&b, have_sig); 1271 buffer_put_cstring(&b, key_ssh_name(id->key)); 1272 } 1273 buffer_put_string(&b, blob, bloblen); 1274 1275 /* generate signature */ 1276 ret = identity_sign(id, &signature, &slen, 1277 buffer_ptr(&b), buffer_len(&b)); 1278 if (ret == -1) { 1279 free(blob); 1280 buffer_free(&b); 1281 return 0; 1282 } 1283#ifdef DEBUG_PK 1284 buffer_dump(&b); 1285#endif 1286 if (datafellows & SSH_BUG_PKSERVICE) { 1287 buffer_clear(&b); 1288 buffer_append(&b, session_id2, session_id2_len); 1289 skip = session_id2_len; 1290 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1291 buffer_put_cstring(&b, authctxt->server_user); 1292 buffer_put_cstring(&b, authctxt->service); 1293 buffer_put_cstring(&b, authctxt->method->name); 1294 buffer_put_char(&b, have_sig); 1295 if (!(datafellows & SSH_BUG_PKAUTH)) 1296 buffer_put_cstring(&b, key_ssh_name(id->key)); 1297 buffer_put_string(&b, blob, bloblen); 1298 } 1299 free(blob); 1300 1301 /* append signature */ 1302 buffer_put_string(&b, signature, slen); 1303 free(signature); 1304 1305 /* skip session id and packet type */ 1306 if (buffer_len(&b) < skip + 1) 1307 fatal("userauth_pubkey: internal error"); 1308 buffer_consume(&b, skip + 1); 1309 1310 /* put remaining data from buffer into packet */ 1311 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1312 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1313 buffer_free(&b); 1314 packet_send(); 1315 1316 return 1; 1317} 1318 1319static int 1320send_pubkey_test(Authctxt *authctxt, Identity *id) 1321{ 1322 u_char *blob; 1323 u_int bloblen, have_sig = 0; 1324 1325 debug3("send_pubkey_test"); 1326 1327 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1328 /* we cannot handle this key */ 1329 debug3("send_pubkey_test: cannot handle key"); 1330 return 0; 1331 } 1332 /* register callback for USERAUTH_PK_OK message */ 1333 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1334 1335 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1336 packet_put_cstring(authctxt->server_user); 1337 packet_put_cstring(authctxt->service); 1338 packet_put_cstring(authctxt->method->name); 1339 packet_put_char(have_sig); 1340 if (!(datafellows & SSH_BUG_PKAUTH)) 1341 packet_put_cstring(key_ssh_name(id->key)); 1342 packet_put_string(blob, bloblen); 1343 free(blob); 1344 packet_send(); 1345 return 1; 1346} 1347 1348static Key * 1349load_identity_file(char *filename, int userprovided) 1350{ 1351 Key *private; 1352 char prompt[300], *passphrase; 1353 int perm_ok = 0, quit, i; 1354 struct stat st; 1355 1356 if (stat(filename, &st) < 0) { 1357 (userprovided ? logit : debug3)("no such identity: %s: %s", 1358 filename, strerror(errno)); 1359 return NULL; 1360 } 1361 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1362 if (!perm_ok) { 1363 if (private != NULL) 1364 key_free(private); 1365 return NULL; 1366 } 1367 if (private == NULL) { 1368 if (options.batch_mode) 1369 return NULL; 1370 snprintf(prompt, sizeof prompt, 1371 "Enter passphrase for key '%.100s': ", filename); 1372 for (i = 0; i < options.number_of_password_prompts; i++) { 1373 passphrase = read_passphrase(prompt, 0); 1374 if (strcmp(passphrase, "") != 0) { 1375 private = key_load_private_type(KEY_UNSPEC, 1376 filename, passphrase, NULL, NULL); 1377 quit = 0; 1378 } else { 1379 debug2("no passphrase given, try next key"); 1380 quit = 1; 1381 } 1382 memset(passphrase, 0, strlen(passphrase)); 1383 free(passphrase); 1384 if (private != NULL || quit) 1385 break; 1386 debug2("bad passphrase given, try again..."); 1387 } 1388 } 1389 return private; 1390} 1391 1392/* 1393 * try keys in the following order: 1394 * 1. agent keys that are found in the config file 1395 * 2. other agent keys 1396 * 3. keys that are only listed in the config file 1397 */ 1398static void 1399pubkey_prepare(Authctxt *authctxt) 1400{ 1401 Identity *id, *id2, *tmp; 1402 Idlist agent, files, *preferred; 1403 Key *key; 1404 AuthenticationConnection *ac; 1405 char *comment; 1406 int i, found; 1407 1408 TAILQ_INIT(&agent); /* keys from the agent */ 1409 TAILQ_INIT(&files); /* keys from the config file */ 1410 preferred = &authctxt->keys; 1411 TAILQ_INIT(preferred); /* preferred order of keys */ 1412 1413 /* list of keys stored in the filesystem and PKCS#11 */ 1414 for (i = 0; i < options.num_identity_files; i++) { 1415 key = options.identity_keys[i]; 1416 if (key && key->type == KEY_RSA1) 1417 continue; 1418 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1419 continue; 1420 options.identity_keys[i] = NULL; 1421 id = xcalloc(1, sizeof(*id)); 1422 id->key = key; 1423 id->filename = xstrdup(options.identity_files[i]); 1424 id->userprovided = options.identity_file_userprovided[i]; 1425 TAILQ_INSERT_TAIL(&files, id, next); 1426 } 1427 /* Prefer PKCS11 keys that are explicitly listed */ 1428 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1429 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0) 1430 continue; 1431 found = 0; 1432 TAILQ_FOREACH(id2, &files, next) { 1433 if (id2->key == NULL || 1434 (id2->key->flags & KEY_FLAG_EXT) != 0) 1435 continue; 1436 if (key_equal(id->key, id2->key)) { 1437 TAILQ_REMOVE(&files, id, next); 1438 TAILQ_INSERT_TAIL(preferred, id, next); 1439 found = 1; 1440 break; 1441 } 1442 } 1443 /* If IdentitiesOnly set and key not found then don't use it */ 1444 if (!found && options.identities_only) { 1445 TAILQ_REMOVE(&files, id, next); 1446 bzero(id, sizeof(*id)); 1447 free(id); 1448 } 1449 } 1450 /* list of keys supported by the agent */ 1451 if ((ac = ssh_get_authentication_connection())) { 1452 for (key = ssh_get_first_identity(ac, &comment, 2); 1453 key != NULL; 1454 key = ssh_get_next_identity(ac, &comment, 2)) { 1455 found = 0; 1456 TAILQ_FOREACH(id, &files, next) { 1457 /* agent keys from the config file are preferred */ 1458 if (key_equal(key, id->key)) { 1459 key_free(key); 1460 free(comment); 1461 TAILQ_REMOVE(&files, id, next); 1462 TAILQ_INSERT_TAIL(preferred, id, next); 1463 id->ac = ac; 1464 found = 1; 1465 break; 1466 } 1467 } 1468 if (!found && !options.identities_only) { 1469 id = xcalloc(1, sizeof(*id)); 1470 id->key = key; 1471 id->filename = comment; 1472 id->ac = ac; 1473 TAILQ_INSERT_TAIL(&agent, id, next); 1474 } 1475 } 1476 /* append remaining agent keys */ 1477 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1478 TAILQ_REMOVE(&agent, id, next); 1479 TAILQ_INSERT_TAIL(preferred, id, next); 1480 } 1481 authctxt->agent = ac; 1482 } 1483 /* append remaining keys from the config file */ 1484 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1485 TAILQ_REMOVE(&files, id, next); 1486 TAILQ_INSERT_TAIL(preferred, id, next); 1487 } 1488 TAILQ_FOREACH(id, preferred, next) { 1489 debug2("key: %s (%p),%s", id->filename, id->key, 1490 id->userprovided ? " explicit" : ""); 1491 } 1492} 1493 1494static void 1495pubkey_cleanup(Authctxt *authctxt) 1496{ 1497 Identity *id; 1498 1499 if (authctxt->agent != NULL) 1500 ssh_close_authentication_connection(authctxt->agent); 1501 for (id = TAILQ_FIRST(&authctxt->keys); id; 1502 id = TAILQ_FIRST(&authctxt->keys)) { 1503 TAILQ_REMOVE(&authctxt->keys, id, next); 1504 if (id->key) 1505 key_free(id->key); 1506 free(id->filename); 1507 free(id); 1508 } 1509} 1510 1511int 1512userauth_pubkey(Authctxt *authctxt) 1513{ 1514 Identity *id; 1515 int sent = 0; 1516 1517 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1518 if (id->tried++) 1519 return (0); 1520 /* move key to the end of the queue */ 1521 TAILQ_REMOVE(&authctxt->keys, id, next); 1522 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1523 /* 1524 * send a test message if we have the public key. for 1525 * encrypted keys we cannot do this and have to load the 1526 * private key instead 1527 */ 1528 if (id->key != NULL) { 1529 if (key_type_plain(id->key->type) == KEY_RSA && 1530 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1531 debug("Skipped %s key %s for RSA/MD5 server", 1532 key_type(id->key), id->filename); 1533 } else if (id->key->type != KEY_RSA1) { 1534 debug("Offering %s public key: %s", 1535 key_type(id->key), id->filename); 1536 sent = send_pubkey_test(authctxt, id); 1537 } 1538 } else { 1539 debug("Trying private key: %s", id->filename); 1540 id->key = load_identity_file(id->filename, 1541 id->userprovided); 1542 if (id->key != NULL) { 1543 id->isprivate = 1; 1544 if (key_type_plain(id->key->type) == KEY_RSA && 1545 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1546 debug("Skipped %s key %s for RSA/MD5 " 1547 "server", key_type(id->key), 1548 id->filename); 1549 } else { 1550 sent = sign_and_send_pubkey( 1551 authctxt, id); 1552 } 1553 key_free(id->key); 1554 id->key = NULL; 1555 } 1556 } 1557 if (sent) 1558 return (sent); 1559 } 1560 return (0); 1561} 1562 1563/* 1564 * Send userauth request message specifying keyboard-interactive method. 1565 */ 1566int 1567userauth_kbdint(Authctxt *authctxt) 1568{ 1569 static int attempt = 0; 1570 1571 if (attempt++ >= options.number_of_password_prompts) 1572 return 0; 1573 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1574 if (attempt > 1 && !authctxt->info_req_seen) { 1575 debug3("userauth_kbdint: disable: no info_req_seen"); 1576 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1577 return 0; 1578 } 1579 1580 debug2("userauth_kbdint"); 1581 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1582 packet_put_cstring(authctxt->server_user); 1583 packet_put_cstring(authctxt->service); 1584 packet_put_cstring(authctxt->method->name); 1585 packet_put_cstring(""); /* lang */ 1586 packet_put_cstring(options.kbd_interactive_devices ? 1587 options.kbd_interactive_devices : ""); 1588 packet_send(); 1589 1590 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1591 return 1; 1592} 1593 1594/* 1595 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1596 */ 1597void 1598input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1599{ 1600 Authctxt *authctxt = ctxt; 1601 char *name, *inst, *lang, *prompt, *response; 1602 u_int num_prompts, i; 1603 int echo = 0; 1604 1605 debug2("input_userauth_info_req"); 1606 1607 if (authctxt == NULL) 1608 fatal("input_userauth_info_req: no authentication context"); 1609 1610 authctxt->info_req_seen = 1; 1611 1612 name = packet_get_string(NULL); 1613 inst = packet_get_string(NULL); 1614 lang = packet_get_string(NULL); 1615 if (strlen(name) > 0) 1616 logit("%s", name); 1617 if (strlen(inst) > 0) 1618 logit("%s", inst); 1619 free(name); 1620 free(inst); 1621 free(lang); 1622 1623 num_prompts = packet_get_int(); 1624 /* 1625 * Begin to build info response packet based on prompts requested. 1626 * We commit to providing the correct number of responses, so if 1627 * further on we run into a problem that prevents this, we have to 1628 * be sure and clean this up and send a correct error response. 1629 */ 1630 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1631 packet_put_int(num_prompts); 1632 1633 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1634 for (i = 0; i < num_prompts; i++) { 1635 prompt = packet_get_string(NULL); 1636 echo = packet_get_char(); 1637 1638 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1639 1640 packet_put_cstring(response); 1641 memset(response, 0, strlen(response)); 1642 free(response); 1643 free(prompt); 1644 } 1645 packet_check_eom(); /* done with parsing incoming message. */ 1646 1647 packet_add_padding(64); 1648 packet_send(); 1649} 1650 1651static int 1652ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1653 u_char *data, u_int datalen) 1654{ 1655 Buffer b; 1656 struct stat st; 1657 pid_t pid; 1658 int to[2], from[2], status, version = 2; 1659 1660 debug2("ssh_keysign called"); 1661 1662 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1663 error("ssh_keysign: not installed: %s", strerror(errno)); 1664 return -1; 1665 } 1666 if (fflush(stdout) != 0) 1667 error("ssh_keysign: fflush: %s", strerror(errno)); 1668 if (pipe(to) < 0) { 1669 error("ssh_keysign: pipe: %s", strerror(errno)); 1670 return -1; 1671 } 1672 if (pipe(from) < 0) { 1673 error("ssh_keysign: pipe: %s", strerror(errno)); 1674 return -1; 1675 } 1676 if ((pid = fork()) < 0) { 1677 error("ssh_keysign: fork: %s", strerror(errno)); 1678 return -1; 1679 } 1680 if (pid == 0) { 1681 /* keep the socket on exec */ 1682 fcntl(packet_get_connection_in(), F_SETFD, 0); 1683 permanently_drop_suid(getuid()); 1684 close(from[0]); 1685 if (dup2(from[1], STDOUT_FILENO) < 0) 1686 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1687 close(to[1]); 1688 if (dup2(to[0], STDIN_FILENO) < 0) 1689 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1690 close(from[1]); 1691 close(to[0]); 1692 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1693 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1694 strerror(errno)); 1695 } 1696 close(from[1]); 1697 close(to[0]); 1698 1699 buffer_init(&b); 1700 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1701 buffer_put_string(&b, data, datalen); 1702 if (ssh_msg_send(to[1], version, &b) == -1) 1703 fatal("ssh_keysign: couldn't send request"); 1704 1705 if (ssh_msg_recv(from[0], &b) < 0) { 1706 error("ssh_keysign: no reply"); 1707 buffer_free(&b); 1708 return -1; 1709 } 1710 close(from[0]); 1711 close(to[1]); 1712 1713 while (waitpid(pid, &status, 0) < 0) 1714 if (errno != EINTR) 1715 break; 1716 1717 if (buffer_get_char(&b) != version) { 1718 error("ssh_keysign: bad version"); 1719 buffer_free(&b); 1720 return -1; 1721 } 1722 *sigp = buffer_get_string(&b, lenp); 1723 buffer_free(&b); 1724 1725 return 0; 1726} 1727 1728int 1729userauth_hostbased(Authctxt *authctxt) 1730{ 1731 Key *private = NULL; 1732 Sensitive *sensitive = authctxt->sensitive; 1733 Buffer b; 1734 u_char *signature, *blob; 1735 char *chost, *pkalg, *p; 1736 const char *service; 1737 u_int blen, slen; 1738 int ok, i, found = 0; 1739 1740 /* check for a useful key */ 1741 for (i = 0; i < sensitive->nkeys; i++) { 1742 private = sensitive->keys[i]; 1743 if (private && private->type != KEY_RSA1) { 1744 found = 1; 1745 /* we take and free the key */ 1746 sensitive->keys[i] = NULL; 1747 break; 1748 } 1749 } 1750 if (!found) { 1751 debug("No more client hostkeys for hostbased authentication."); 1752 return 0; 1753 } 1754 if (key_to_blob(private, &blob, &blen) == 0) { 1755 key_free(private); 1756 return 0; 1757 } 1758 /* figure out a name for the client host */ 1759 p = get_local_name(packet_get_connection_in()); 1760 if (p == NULL) { 1761 error("userauth_hostbased: cannot get local ipaddr/name"); 1762 key_free(private); 1763 free(blob); 1764 return 0; 1765 } 1766 xasprintf(&chost, "%s.", p); 1767 debug2("userauth_hostbased: chost %s", chost); 1768 free(p); 1769 1770 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1771 authctxt->service; 1772 pkalg = xstrdup(key_ssh_name(private)); 1773 buffer_init(&b); 1774 /* construct data */ 1775 buffer_put_string(&b, session_id2, session_id2_len); 1776 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1777 buffer_put_cstring(&b, authctxt->server_user); 1778 buffer_put_cstring(&b, service); 1779 buffer_put_cstring(&b, authctxt->method->name); 1780 buffer_put_cstring(&b, pkalg); 1781 buffer_put_string(&b, blob, blen); 1782 buffer_put_cstring(&b, chost); 1783 buffer_put_cstring(&b, authctxt->local_user); 1784#ifdef DEBUG_PK 1785 buffer_dump(&b); 1786#endif 1787 if (sensitive->external_keysign) 1788 ok = ssh_keysign(private, &signature, &slen, 1789 buffer_ptr(&b), buffer_len(&b)); 1790 else 1791 ok = key_sign(private, &signature, &slen, 1792 buffer_ptr(&b), buffer_len(&b)); 1793 key_free(private); 1794 buffer_free(&b); 1795 if (ok != 0) { 1796 error("key_sign failed"); 1797 free(chost); 1798 free(pkalg); 1799 free(blob); 1800 return 0; 1801 } 1802 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1803 packet_put_cstring(authctxt->server_user); 1804 packet_put_cstring(authctxt->service); 1805 packet_put_cstring(authctxt->method->name); 1806 packet_put_cstring(pkalg); 1807 packet_put_string(blob, blen); 1808 packet_put_cstring(chost); 1809 packet_put_cstring(authctxt->local_user); 1810 packet_put_string(signature, slen); 1811 memset(signature, 's', slen); 1812 free(signature); 1813 free(chost); 1814 free(pkalg); 1815 free(blob); 1816 1817 packet_send(); 1818 return 1; 1819} 1820 1821#ifdef JPAKE 1822int 1823userauth_jpake(Authctxt *authctxt) 1824{ 1825 struct jpake_ctx *pctx; 1826 u_char *x1_proof, *x2_proof; 1827 u_int x1_proof_len, x2_proof_len; 1828 static int attempt = 0; /* XXX share with userauth_password's? */ 1829 1830 if (attempt++ >= options.number_of_password_prompts) 1831 return 0; 1832 if (attempt != 1) 1833 error("Permission denied, please try again."); 1834 1835 if (authctxt->methoddata != NULL) 1836 fatal("%s: authctxt->methoddata already set (%p)", 1837 __func__, authctxt->methoddata); 1838 1839 authctxt->methoddata = pctx = jpake_new(); 1840 1841 /* 1842 * Send request immediately, to get the protocol going while 1843 * we do the initial computations. 1844 */ 1845 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1846 packet_put_cstring(authctxt->server_user); 1847 packet_put_cstring(authctxt->service); 1848 packet_put_cstring(authctxt->method->name); 1849 packet_send(); 1850 packet_write_wait(); 1851 1852 jpake_step1(pctx->grp, 1853 &pctx->client_id, &pctx->client_id_len, 1854 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1855 &x1_proof, &x1_proof_len, 1856 &x2_proof, &x2_proof_len); 1857 1858 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1859 1860 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1861 packet_put_string(pctx->client_id, pctx->client_id_len); 1862 packet_put_bignum2(pctx->g_x1); 1863 packet_put_bignum2(pctx->g_x2); 1864 packet_put_string(x1_proof, x1_proof_len); 1865 packet_put_string(x2_proof, x2_proof_len); 1866 packet_send(); 1867 1868 bzero(x1_proof, x1_proof_len); 1869 bzero(x2_proof, x2_proof_len); 1870 free(x1_proof); 1871 free(x2_proof); 1872 1873 /* Expect step 1 packet from peer */ 1874 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1875 input_userauth_jpake_server_step1); 1876 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1877 &input_userauth_success_unexpected); 1878 1879 return 1; 1880} 1881 1882void 1883userauth_jpake_cleanup(Authctxt *authctxt) 1884{ 1885 debug3("%s: clean up", __func__); 1886 if (authctxt->methoddata != NULL) { 1887 jpake_free(authctxt->methoddata); 1888 authctxt->methoddata = NULL; 1889 } 1890 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1891} 1892#endif /* JPAKE */ 1893 1894/* find auth method */ 1895 1896/* 1897 * given auth method name, if configurable options permit this method fill 1898 * in auth_ident field and return true, otherwise return false. 1899 */ 1900static int 1901authmethod_is_enabled(Authmethod *method) 1902{ 1903 if (method == NULL) 1904 return 0; 1905 /* return false if options indicate this method is disabled */ 1906 if (method->enabled == NULL || *method->enabled == 0) 1907 return 0; 1908 /* return false if batch mode is enabled but method needs interactive mode */ 1909 if (method->batch_flag != NULL && *method->batch_flag != 0) 1910 return 0; 1911 return 1; 1912} 1913 1914static Authmethod * 1915authmethod_lookup(const char *name) 1916{ 1917 Authmethod *method = NULL; 1918 if (name != NULL) 1919 for (method = authmethods; method->name != NULL; method++) 1920 if (strcmp(name, method->name) == 0) 1921 return method; 1922 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1923 return NULL; 1924} 1925 1926/* XXX internal state */ 1927static Authmethod *current = NULL; 1928static char *supported = NULL; 1929static char *preferred = NULL; 1930 1931/* 1932 * Given the authentication method list sent by the server, return the 1933 * next method we should try. If the server initially sends a nil list, 1934 * use a built-in default list. 1935 */ 1936static Authmethod * 1937authmethod_get(char *authlist) 1938{ 1939 char *name = NULL; 1940 u_int next; 1941 1942 /* Use a suitable default if we're passed a nil list. */ 1943 if (authlist == NULL || strlen(authlist) == 0) 1944 authlist = options.preferred_authentications; 1945 1946 if (supported == NULL || strcmp(authlist, supported) != 0) { 1947 debug3("start over, passed a different list %s", authlist); 1948 free(supported); 1949 supported = xstrdup(authlist); 1950 preferred = options.preferred_authentications; 1951 debug3("preferred %s", preferred); 1952 current = NULL; 1953 } else if (current != NULL && authmethod_is_enabled(current)) 1954 return current; 1955 1956 for (;;) { 1957 if ((name = match_list(preferred, supported, &next)) == NULL) { 1958 debug("No more authentication methods to try."); 1959 current = NULL; 1960 return NULL; 1961 } 1962 preferred += next; 1963 debug3("authmethod_lookup %s", name); 1964 debug3("remaining preferred: %s", preferred); 1965 if ((current = authmethod_lookup(name)) != NULL && 1966 authmethod_is_enabled(current)) { 1967 debug3("authmethod_is_enabled %s", name); 1968 debug("Next authentication method: %s", name); 1969 free(name); 1970 return current; 1971 } 1972 free(name); 1973 } 1974} 1975 1976static char * 1977authmethods_get(void) 1978{ 1979 Authmethod *method = NULL; 1980 Buffer b; 1981 char *list; 1982 1983 buffer_init(&b); 1984 for (method = authmethods; method->name != NULL; method++) { 1985 if (authmethod_is_enabled(method)) { 1986 if (buffer_len(&b) > 0) 1987 buffer_append(&b, ",", 1); 1988 buffer_append(&b, method->name, strlen(method->name)); 1989 } 1990 } 1991 buffer_append(&b, "\0", 1); 1992 list = xstrdup(buffer_ptr(&b)); 1993 buffer_free(&b); 1994 return list; 1995} 1996 1997