sshconnect2.c revision 294328
1/* $OpenBSD: sshconnect2.c,v 1.210 2014/07/15 15:54:14 millert Exp $ */ 2/* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27#include "includes.h" 28 29#include <sys/types.h> 30#include <sys/socket.h> 31#include <sys/wait.h> 32#include <sys/stat.h> 33 34#include <errno.h> 35#include <fcntl.h> 36#include <netdb.h> 37#include <pwd.h> 38#include <signal.h> 39#include <stdarg.h> 40#include <stdio.h> 41#include <string.h> 42#include <unistd.h> 43#if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 44#include <vis.h> 45#endif 46 47#include "openbsd-compat/sys-queue.h" 48 49#include "xmalloc.h" 50#include "ssh.h" 51#include "ssh2.h" 52#include "buffer.h" 53#include "packet.h" 54#include "compat.h" 55#include "cipher.h" 56#include "key.h" 57#include "kex.h" 58#include "myproposal.h" 59#include "sshconnect.h" 60#include "authfile.h" 61#include "dh.h" 62#include "authfd.h" 63#include "log.h" 64#include "misc.h" 65#include "readconf.h" 66#include "match.h" 67#include "dispatch.h" 68#include "canohost.h" 69#include "msg.h" 70#include "pathnames.h" 71#include "uidswap.h" 72#include "hostfile.h" 73 74#ifdef GSSAPI 75#include "ssh-gss.h" 76#endif 77 78/* import */ 79extern char *client_version_string; 80extern char *server_version_string; 81extern Options options; 82 83/* 84 * SSH2 key exchange 85 */ 86 87u_char *session_id2 = NULL; 88u_int session_id2_len = 0; 89 90char *xxx_host; 91struct sockaddr *xxx_hostaddr; 92 93Kex *xxx_kex = NULL; 94 95static int 96verify_host_key_callback(Key *hostkey) 97{ 98 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 99 fatal("Host key verification failed."); 100 return 0; 101} 102 103static char * 104order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 105{ 106 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 107 size_t maxlen; 108 struct hostkeys *hostkeys; 109 int ktype; 110 u_int i; 111 112 /* Find all hostkeys for this hostname */ 113 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 114 hostkeys = init_hostkeys(); 115 for (i = 0; i < options.num_user_hostfiles; i++) 116 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 117 for (i = 0; i < options.num_system_hostfiles; i++) 118 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 119 120 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 121 maxlen = strlen(avail) + 1; 122 first = xmalloc(maxlen); 123 last = xmalloc(maxlen); 124 *first = *last = '\0'; 125 126#define ALG_APPEND(to, from) \ 127 do { \ 128 if (*to != '\0') \ 129 strlcat(to, ",", maxlen); \ 130 strlcat(to, from, maxlen); \ 131 } while (0) 132 133 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 134 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 135 fatal("%s: unknown alg %s", __func__, alg); 136 if (lookup_key_in_hostkeys_by_type(hostkeys, 137 key_type_plain(ktype), NULL)) 138 ALG_APPEND(first, alg); 139 else 140 ALG_APPEND(last, alg); 141 } 142#undef ALG_APPEND 143 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 144 if (*first != '\0') 145 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 146 147 free(first); 148 free(last); 149 free(hostname); 150 free(oavail); 151 free_hostkeys(hostkeys); 152 153 return ret; 154} 155 156void 157ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 158{ 159 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 160 Kex *kex; 161 162 xxx_host = host; 163 xxx_hostaddr = hostaddr; 164 165 if (options.ciphers == (char *)-1) { 166 logit("No valid ciphers for protocol version 2 given, using defaults."); 167 options.ciphers = NULL; 168 } 169 if (options.ciphers != NULL) { 170 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 171 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 172 } 173 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 174 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 175 myproposal[PROPOSAL_ENC_ALGS_STOC] = 176 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 177 if (options.compression) { 178 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 179 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 180 } else { 181 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 182 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 183 } 184 if (options.macs != NULL) { 185 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 186 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 187 } 188 if (options.hostkeyalgorithms != NULL) 189 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 190 compat_pkalg_proposal(options.hostkeyalgorithms); 191 else { 192 /* Prefer algorithms that we already have keys for */ 193 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 194 compat_pkalg_proposal( 195 order_hostkeyalgs(host, hostaddr, port)); 196 } 197 if (options.kex_algorithms != NULL) 198 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 199 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 200 myproposal[PROPOSAL_KEX_ALGS]); 201 202 if (options.rekey_limit || options.rekey_interval) 203 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 204 (time_t)options.rekey_interval); 205 206 /* start key exchange */ 207 kex = kex_setup(myproposal); 208#ifdef WITH_OPENSSL 209 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 210 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 211 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 212 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 213 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 214#endif 215 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 216 kex->client_version_string=client_version_string; 217 kex->server_version_string=server_version_string; 218 kex->verify_host_key=&verify_host_key_callback; 219 220 xxx_kex = kex; 221 222 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 223 224 if (options.use_roaming && !kex->roaming) { 225 debug("Roaming not allowed by server"); 226 options.use_roaming = 0; 227 } 228 229 session_id2 = kex->session_id; 230 session_id2_len = kex->session_id_len; 231 232#ifdef DEBUG_KEXDH 233 /* send 1st encrypted/maced/compressed message */ 234 packet_start(SSH2_MSG_IGNORE); 235 packet_put_cstring("markus"); 236 packet_send(); 237 packet_write_wait(); 238#endif 239} 240 241/* 242 * Authenticate user 243 */ 244 245typedef struct Authctxt Authctxt; 246typedef struct Authmethod Authmethod; 247typedef struct identity Identity; 248typedef struct idlist Idlist; 249 250struct identity { 251 TAILQ_ENTRY(identity) next; 252 AuthenticationConnection *ac; /* set if agent supports key */ 253 Key *key; /* public/private key */ 254 char *filename; /* comment for agent-only keys */ 255 int tried; 256 int isprivate; /* key points to the private key */ 257 int userprovided; 258}; 259TAILQ_HEAD(idlist, identity); 260 261struct Authctxt { 262 const char *server_user; 263 const char *local_user; 264 const char *host; 265 const char *service; 266 Authmethod *method; 267 sig_atomic_t success; 268 char *authlist; 269 /* pubkey */ 270 Idlist keys; 271 AuthenticationConnection *agent; 272 /* hostbased */ 273 Sensitive *sensitive; 274 /* kbd-interactive */ 275 int info_req_seen; 276 /* generic */ 277 void *methoddata; 278}; 279struct Authmethod { 280 char *name; /* string to compare against server's list */ 281 int (*userauth)(Authctxt *authctxt); 282 void (*cleanup)(Authctxt *authctxt); 283 int *enabled; /* flag in option struct that enables method */ 284 int *batch_flag; /* flag in option struct that disables method */ 285}; 286 287void input_userauth_success(int, u_int32_t, void *); 288void input_userauth_success_unexpected(int, u_int32_t, void *); 289void input_userauth_failure(int, u_int32_t, void *); 290void input_userauth_banner(int, u_int32_t, void *); 291void input_userauth_error(int, u_int32_t, void *); 292void input_userauth_info_req(int, u_int32_t, void *); 293void input_userauth_pk_ok(int, u_int32_t, void *); 294void input_userauth_passwd_changereq(int, u_int32_t, void *); 295 296int userauth_none(Authctxt *); 297int userauth_pubkey(Authctxt *); 298int userauth_passwd(Authctxt *); 299int userauth_kbdint(Authctxt *); 300int userauth_hostbased(Authctxt *); 301 302#ifdef GSSAPI 303int userauth_gssapi(Authctxt *authctxt); 304void input_gssapi_response(int type, u_int32_t, void *); 305void input_gssapi_token(int type, u_int32_t, void *); 306void input_gssapi_hash(int type, u_int32_t, void *); 307void input_gssapi_error(int, u_int32_t, void *); 308void input_gssapi_errtok(int, u_int32_t, void *); 309#endif 310 311void userauth(Authctxt *, char *); 312 313static int sign_and_send_pubkey(Authctxt *, Identity *); 314static void pubkey_prepare(Authctxt *); 315static void pubkey_cleanup(Authctxt *); 316static Key *load_identity_file(char *, int); 317 318static Authmethod *authmethod_get(char *authlist); 319static Authmethod *authmethod_lookup(const char *name); 320static char *authmethods_get(void); 321 322Authmethod authmethods[] = { 323#ifdef GSSAPI 324 {"gssapi-with-mic", 325 userauth_gssapi, 326 NULL, 327 &options.gss_authentication, 328 NULL}, 329#endif 330 {"hostbased", 331 userauth_hostbased, 332 NULL, 333 &options.hostbased_authentication, 334 NULL}, 335 {"publickey", 336 userauth_pubkey, 337 NULL, 338 &options.pubkey_authentication, 339 NULL}, 340 {"keyboard-interactive", 341 userauth_kbdint, 342 NULL, 343 &options.kbd_interactive_authentication, 344 &options.batch_mode}, 345 {"password", 346 userauth_passwd, 347 NULL, 348 &options.password_authentication, 349 &options.batch_mode}, 350 {"none", 351 userauth_none, 352 NULL, 353 NULL, 354 NULL}, 355 {NULL, NULL, NULL, NULL, NULL} 356}; 357 358void 359ssh_userauth2(const char *local_user, const char *server_user, char *host, 360 Sensitive *sensitive) 361{ 362 Authctxt authctxt; 363 int type; 364 365 if (options.challenge_response_authentication) 366 options.kbd_interactive_authentication = 1; 367 368 packet_start(SSH2_MSG_SERVICE_REQUEST); 369 packet_put_cstring("ssh-userauth"); 370 packet_send(); 371 debug("SSH2_MSG_SERVICE_REQUEST sent"); 372 packet_write_wait(); 373 type = packet_read(); 374 if (type != SSH2_MSG_SERVICE_ACCEPT) 375 fatal("Server denied authentication request: %d", type); 376 if (packet_remaining() > 0) { 377 char *reply = packet_get_string(NULL); 378 debug2("service_accept: %s", reply); 379 free(reply); 380 } else { 381 debug2("buggy server: service_accept w/o service"); 382 } 383 packet_check_eom(); 384 debug("SSH2_MSG_SERVICE_ACCEPT received"); 385 386 if (options.preferred_authentications == NULL) 387 options.preferred_authentications = authmethods_get(); 388 389 /* setup authentication context */ 390 memset(&authctxt, 0, sizeof(authctxt)); 391 pubkey_prepare(&authctxt); 392 authctxt.server_user = server_user; 393 authctxt.local_user = local_user; 394 authctxt.host = host; 395 authctxt.service = "ssh-connection"; /* service name */ 396 authctxt.success = 0; 397 authctxt.method = authmethod_lookup("none"); 398 authctxt.authlist = NULL; 399 authctxt.methoddata = NULL; 400 authctxt.sensitive = sensitive; 401 authctxt.info_req_seen = 0; 402 if (authctxt.method == NULL) 403 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 404 405 /* initial userauth request */ 406 userauth_none(&authctxt); 407 408 dispatch_init(&input_userauth_error); 409 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 410 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 411 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 412 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 413 414 pubkey_cleanup(&authctxt); 415 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 416 417 debug("Authentication succeeded (%s).", authctxt.method->name); 418} 419 420void 421userauth(Authctxt *authctxt, char *authlist) 422{ 423 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 424 authctxt->method->cleanup(authctxt); 425 426 free(authctxt->methoddata); 427 authctxt->methoddata = NULL; 428 if (authlist == NULL) { 429 authlist = authctxt->authlist; 430 } else { 431 free(authctxt->authlist); 432 authctxt->authlist = authlist; 433 } 434 for (;;) { 435 Authmethod *method = authmethod_get(authlist); 436 if (method == NULL) 437 fatal("Permission denied (%s).", authlist); 438 authctxt->method = method; 439 440 /* reset the per method handler */ 441 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 442 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 443 444 /* and try new method */ 445 if (method->userauth(authctxt) != 0) { 446 debug2("we sent a %s packet, wait for reply", method->name); 447 break; 448 } else { 449 debug2("we did not send a packet, disable method"); 450 method->enabled = NULL; 451 } 452 } 453} 454 455/* ARGSUSED */ 456void 457input_userauth_error(int type, u_int32_t seq, void *ctxt) 458{ 459 fatal("input_userauth_error: bad message during authentication: " 460 "type %d", type); 461} 462 463/* ARGSUSED */ 464void 465input_userauth_banner(int type, u_int32_t seq, void *ctxt) 466{ 467 char *msg, *raw, *lang; 468 u_int len; 469 470 debug3("input_userauth_banner"); 471 raw = packet_get_string(&len); 472 lang = packet_get_string(NULL); 473 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 474 if (len > 65536) 475 len = 65536; 476 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 477 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 478 fprintf(stderr, "%s", msg); 479 free(msg); 480 } 481 free(raw); 482 free(lang); 483} 484 485/* ARGSUSED */ 486void 487input_userauth_success(int type, u_int32_t seq, void *ctxt) 488{ 489 Authctxt *authctxt = ctxt; 490 491 if (authctxt == NULL) 492 fatal("input_userauth_success: no authentication context"); 493 free(authctxt->authlist); 494 authctxt->authlist = NULL; 495 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 496 authctxt->method->cleanup(authctxt); 497 free(authctxt->methoddata); 498 authctxt->methoddata = NULL; 499 authctxt->success = 1; /* break out */ 500} 501 502void 503input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 504{ 505 Authctxt *authctxt = ctxt; 506 507 if (authctxt == NULL) 508 fatal("%s: no authentication context", __func__); 509 510 fatal("Unexpected authentication success during %s.", 511 authctxt->method->name); 512} 513 514/* ARGSUSED */ 515void 516input_userauth_failure(int type, u_int32_t seq, void *ctxt) 517{ 518 Authctxt *authctxt = ctxt; 519 char *authlist = NULL; 520 int partial; 521 522 if (authctxt == NULL) 523 fatal("input_userauth_failure: no authentication context"); 524 525 authlist = packet_get_string(NULL); 526 partial = packet_get_char(); 527 packet_check_eom(); 528 529 if (partial != 0) { 530 logit("Authenticated with partial success."); 531 /* reset state */ 532 pubkey_cleanup(authctxt); 533 pubkey_prepare(authctxt); 534 } 535 debug("Authentications that can continue: %s", authlist); 536 537 userauth(authctxt, authlist); 538} 539 540/* ARGSUSED */ 541void 542input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 543{ 544 Authctxt *authctxt = ctxt; 545 Key *key = NULL; 546 Identity *id = NULL; 547 Buffer b; 548 int pktype, sent = 0; 549 u_int alen, blen; 550 char *pkalg, *fp; 551 u_char *pkblob; 552 553 if (authctxt == NULL) 554 fatal("input_userauth_pk_ok: no authentication context"); 555 if (datafellows & SSH_BUG_PKOK) { 556 /* this is similar to SSH_BUG_PKAUTH */ 557 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 558 pkblob = packet_get_string(&blen); 559 buffer_init(&b); 560 buffer_append(&b, pkblob, blen); 561 pkalg = buffer_get_string(&b, &alen); 562 buffer_free(&b); 563 } else { 564 pkalg = packet_get_string(&alen); 565 pkblob = packet_get_string(&blen); 566 } 567 packet_check_eom(); 568 569 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 570 571 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 572 debug("unknown pkalg %s", pkalg); 573 goto done; 574 } 575 if ((key = key_from_blob(pkblob, blen)) == NULL) { 576 debug("no key from blob. pkalg %s", pkalg); 577 goto done; 578 } 579 if (key->type != pktype) { 580 error("input_userauth_pk_ok: type mismatch " 581 "for decoded key (received %d, expected %d)", 582 key->type, pktype); 583 goto done; 584 } 585 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 586 debug2("input_userauth_pk_ok: fp %s", fp); 587 free(fp); 588 589 /* 590 * search keys in the reverse order, because last candidate has been 591 * moved to the end of the queue. this also avoids confusion by 592 * duplicate keys 593 */ 594 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 595 if (key_equal(key, id->key)) { 596 sent = sign_and_send_pubkey(authctxt, id); 597 break; 598 } 599 } 600done: 601 if (key != NULL) 602 key_free(key); 603 free(pkalg); 604 free(pkblob); 605 606 /* try another method if we did not send a packet */ 607 if (sent == 0) 608 userauth(authctxt, NULL); 609} 610 611#ifdef GSSAPI 612int 613userauth_gssapi(Authctxt *authctxt) 614{ 615 Gssctxt *gssctxt = NULL; 616 static gss_OID_set gss_supported = NULL; 617 static u_int mech = 0; 618 OM_uint32 min; 619 int ok = 0; 620 621 /* Try one GSSAPI method at a time, rather than sending them all at 622 * once. */ 623 624 if (gss_supported == NULL) 625 gss_indicate_mechs(&min, &gss_supported); 626 627 /* Check to see if the mechanism is usable before we offer it */ 628 while (mech < gss_supported->count && !ok) { 629 /* My DER encoding requires length<128 */ 630 if (gss_supported->elements[mech].length < 128 && 631 ssh_gssapi_check_mechanism(&gssctxt, 632 &gss_supported->elements[mech], authctxt->host)) { 633 ok = 1; /* Mechanism works */ 634 } else { 635 mech++; 636 } 637 } 638 639 if (!ok) 640 return 0; 641 642 authctxt->methoddata=(void *)gssctxt; 643 644 packet_start(SSH2_MSG_USERAUTH_REQUEST); 645 packet_put_cstring(authctxt->server_user); 646 packet_put_cstring(authctxt->service); 647 packet_put_cstring(authctxt->method->name); 648 649 packet_put_int(1); 650 651 packet_put_int((gss_supported->elements[mech].length) + 2); 652 packet_put_char(SSH_GSS_OIDTYPE); 653 packet_put_char(gss_supported->elements[mech].length); 654 packet_put_raw(gss_supported->elements[mech].elements, 655 gss_supported->elements[mech].length); 656 657 packet_send(); 658 659 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 660 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 661 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 662 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 663 664 mech++; /* Move along to next candidate */ 665 666 return 1; 667} 668 669static OM_uint32 670process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 671{ 672 Authctxt *authctxt = ctxt; 673 Gssctxt *gssctxt = authctxt->methoddata; 674 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 675 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 676 gss_buffer_desc gssbuf; 677 OM_uint32 status, ms, flags; 678 Buffer b; 679 680 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 681 recv_tok, &send_tok, &flags); 682 683 if (send_tok.length > 0) { 684 if (GSS_ERROR(status)) 685 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 686 else 687 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 688 689 packet_put_string(send_tok.value, send_tok.length); 690 packet_send(); 691 gss_release_buffer(&ms, &send_tok); 692 } 693 694 if (status == GSS_S_COMPLETE) { 695 /* send either complete or MIC, depending on mechanism */ 696 if (!(flags & GSS_C_INTEG_FLAG)) { 697 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 698 packet_send(); 699 } else { 700 ssh_gssapi_buildmic(&b, authctxt->server_user, 701 authctxt->service, "gssapi-with-mic"); 702 703 gssbuf.value = buffer_ptr(&b); 704 gssbuf.length = buffer_len(&b); 705 706 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 707 708 if (!GSS_ERROR(status)) { 709 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 710 packet_put_string(mic.value, mic.length); 711 712 packet_send(); 713 } 714 715 buffer_free(&b); 716 gss_release_buffer(&ms, &mic); 717 } 718 } 719 720 return status; 721} 722 723/* ARGSUSED */ 724void 725input_gssapi_response(int type, u_int32_t plen, void *ctxt) 726{ 727 Authctxt *authctxt = ctxt; 728 Gssctxt *gssctxt; 729 int oidlen; 730 char *oidv; 731 732 if (authctxt == NULL) 733 fatal("input_gssapi_response: no authentication context"); 734 gssctxt = authctxt->methoddata; 735 736 /* Setup our OID */ 737 oidv = packet_get_string(&oidlen); 738 739 if (oidlen <= 2 || 740 oidv[0] != SSH_GSS_OIDTYPE || 741 oidv[1] != oidlen - 2) { 742 free(oidv); 743 debug("Badly encoded mechanism OID received"); 744 userauth(authctxt, NULL); 745 return; 746 } 747 748 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 749 fatal("Server returned different OID than expected"); 750 751 packet_check_eom(); 752 753 free(oidv); 754 755 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 756 /* Start again with next method on list */ 757 debug("Trying to start again"); 758 userauth(authctxt, NULL); 759 return; 760 } 761} 762 763/* ARGSUSED */ 764void 765input_gssapi_token(int type, u_int32_t plen, void *ctxt) 766{ 767 Authctxt *authctxt = ctxt; 768 gss_buffer_desc recv_tok; 769 OM_uint32 status; 770 u_int slen; 771 772 if (authctxt == NULL) 773 fatal("input_gssapi_response: no authentication context"); 774 775 recv_tok.value = packet_get_string(&slen); 776 recv_tok.length = slen; /* safe typecast */ 777 778 packet_check_eom(); 779 780 status = process_gssapi_token(ctxt, &recv_tok); 781 782 free(recv_tok.value); 783 784 if (GSS_ERROR(status)) { 785 /* Start again with the next method in the list */ 786 userauth(authctxt, NULL); 787 return; 788 } 789} 790 791/* ARGSUSED */ 792void 793input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 794{ 795 Authctxt *authctxt = ctxt; 796 Gssctxt *gssctxt; 797 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 798 gss_buffer_desc recv_tok; 799 OM_uint32 ms; 800 u_int len; 801 802 if (authctxt == NULL) 803 fatal("input_gssapi_response: no authentication context"); 804 gssctxt = authctxt->methoddata; 805 806 recv_tok.value = packet_get_string(&len); 807 recv_tok.length = len; 808 809 packet_check_eom(); 810 811 /* Stick it into GSSAPI and see what it says */ 812 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 813 &recv_tok, &send_tok, NULL); 814 815 free(recv_tok.value); 816 gss_release_buffer(&ms, &send_tok); 817 818 /* Server will be returning a failed packet after this one */ 819} 820 821/* ARGSUSED */ 822void 823input_gssapi_error(int type, u_int32_t plen, void *ctxt) 824{ 825 char *msg; 826 char *lang; 827 828 /* maj */(void)packet_get_int(); 829 /* min */(void)packet_get_int(); 830 msg=packet_get_string(NULL); 831 lang=packet_get_string(NULL); 832 833 packet_check_eom(); 834 835 debug("Server GSSAPI Error:\n%s", msg); 836 free(msg); 837 free(lang); 838} 839#endif /* GSSAPI */ 840 841int 842userauth_none(Authctxt *authctxt) 843{ 844 /* initial userauth request */ 845 packet_start(SSH2_MSG_USERAUTH_REQUEST); 846 packet_put_cstring(authctxt->server_user); 847 packet_put_cstring(authctxt->service); 848 packet_put_cstring(authctxt->method->name); 849 packet_send(); 850 return 1; 851} 852 853int 854userauth_passwd(Authctxt *authctxt) 855{ 856 static int attempt = 0; 857 char prompt[150]; 858 char *password; 859 const char *host = options.host_key_alias ? options.host_key_alias : 860 authctxt->host; 861 862 if (attempt++ >= options.number_of_password_prompts) 863 return 0; 864 865 if (attempt != 1) 866 error("Permission denied, please try again."); 867 868 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 869 authctxt->server_user, host); 870 password = read_passphrase(prompt, 0); 871 packet_start(SSH2_MSG_USERAUTH_REQUEST); 872 packet_put_cstring(authctxt->server_user); 873 packet_put_cstring(authctxt->service); 874 packet_put_cstring(authctxt->method->name); 875 packet_put_char(0); 876 packet_put_cstring(password); 877 explicit_bzero(password, strlen(password)); 878 free(password); 879 packet_add_padding(64); 880 packet_send(); 881 882 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 883 &input_userauth_passwd_changereq); 884 885 return 1; 886} 887 888/* 889 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 890 */ 891/* ARGSUSED */ 892void 893input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 894{ 895 Authctxt *authctxt = ctxt; 896 char *info, *lang, *password = NULL, *retype = NULL; 897 char prompt[150]; 898 const char *host = options.host_key_alias ? options.host_key_alias : 899 authctxt->host; 900 901 debug2("input_userauth_passwd_changereq"); 902 903 if (authctxt == NULL) 904 fatal("input_userauth_passwd_changereq: " 905 "no authentication context"); 906 907 info = packet_get_string(NULL); 908 lang = packet_get_string(NULL); 909 if (strlen(info) > 0) 910 logit("%s", info); 911 free(info); 912 free(lang); 913 packet_start(SSH2_MSG_USERAUTH_REQUEST); 914 packet_put_cstring(authctxt->server_user); 915 packet_put_cstring(authctxt->service); 916 packet_put_cstring(authctxt->method->name); 917 packet_put_char(1); /* additional info */ 918 snprintf(prompt, sizeof(prompt), 919 "Enter %.30s@%.128s's old password: ", 920 authctxt->server_user, host); 921 password = read_passphrase(prompt, 0); 922 packet_put_cstring(password); 923 explicit_bzero(password, strlen(password)); 924 free(password); 925 password = NULL; 926 while (password == NULL) { 927 snprintf(prompt, sizeof(prompt), 928 "Enter %.30s@%.128s's new password: ", 929 authctxt->server_user, host); 930 password = read_passphrase(prompt, RP_ALLOW_EOF); 931 if (password == NULL) { 932 /* bail out */ 933 return; 934 } 935 snprintf(prompt, sizeof(prompt), 936 "Retype %.30s@%.128s's new password: ", 937 authctxt->server_user, host); 938 retype = read_passphrase(prompt, 0); 939 if (strcmp(password, retype) != 0) { 940 explicit_bzero(password, strlen(password)); 941 free(password); 942 logit("Mismatch; try again, EOF to quit."); 943 password = NULL; 944 } 945 explicit_bzero(retype, strlen(retype)); 946 free(retype); 947 } 948 packet_put_cstring(password); 949 explicit_bzero(password, strlen(password)); 950 free(password); 951 packet_add_padding(64); 952 packet_send(); 953 954 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 955 &input_userauth_passwd_changereq); 956} 957 958static int 959identity_sign(Identity *id, u_char **sigp, u_int *lenp, 960 u_char *data, u_int datalen) 961{ 962 Key *prv; 963 int ret; 964 965 /* the agent supports this key */ 966 if (id->ac) 967 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 968 data, datalen)); 969 /* 970 * we have already loaded the private key or 971 * the private key is stored in external hardware 972 */ 973 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 974 return (key_sign(id->key, sigp, lenp, data, datalen)); 975 /* load the private key from the file */ 976 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 977 return (-1); 978 ret = key_sign(prv, sigp, lenp, data, datalen); 979 key_free(prv); 980 return (ret); 981} 982 983static int 984sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 985{ 986 Buffer b; 987 u_char *blob, *signature; 988 u_int bloblen, slen; 989 u_int skip = 0; 990 int ret = -1; 991 int have_sig = 1; 992 char *fp; 993 994 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 995 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 996 free(fp); 997 998 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 999 /* we cannot handle this key */ 1000 debug3("sign_and_send_pubkey: cannot handle key"); 1001 return 0; 1002 } 1003 /* data to be signed */ 1004 buffer_init(&b); 1005 if (datafellows & SSH_OLD_SESSIONID) { 1006 buffer_append(&b, session_id2, session_id2_len); 1007 skip = session_id2_len; 1008 } else { 1009 buffer_put_string(&b, session_id2, session_id2_len); 1010 skip = buffer_len(&b); 1011 } 1012 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1013 buffer_put_cstring(&b, authctxt->server_user); 1014 buffer_put_cstring(&b, 1015 datafellows & SSH_BUG_PKSERVICE ? 1016 "ssh-userauth" : 1017 authctxt->service); 1018 if (datafellows & SSH_BUG_PKAUTH) { 1019 buffer_put_char(&b, have_sig); 1020 } else { 1021 buffer_put_cstring(&b, authctxt->method->name); 1022 buffer_put_char(&b, have_sig); 1023 buffer_put_cstring(&b, key_ssh_name(id->key)); 1024 } 1025 buffer_put_string(&b, blob, bloblen); 1026 1027 /* generate signature */ 1028 ret = identity_sign(id, &signature, &slen, 1029 buffer_ptr(&b), buffer_len(&b)); 1030 if (ret == -1) { 1031 free(blob); 1032 buffer_free(&b); 1033 return 0; 1034 } 1035#ifdef DEBUG_PK 1036 buffer_dump(&b); 1037#endif 1038 if (datafellows & SSH_BUG_PKSERVICE) { 1039 buffer_clear(&b); 1040 buffer_append(&b, session_id2, session_id2_len); 1041 skip = session_id2_len; 1042 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1043 buffer_put_cstring(&b, authctxt->server_user); 1044 buffer_put_cstring(&b, authctxt->service); 1045 buffer_put_cstring(&b, authctxt->method->name); 1046 buffer_put_char(&b, have_sig); 1047 if (!(datafellows & SSH_BUG_PKAUTH)) 1048 buffer_put_cstring(&b, key_ssh_name(id->key)); 1049 buffer_put_string(&b, blob, bloblen); 1050 } 1051 free(blob); 1052 1053 /* append signature */ 1054 buffer_put_string(&b, signature, slen); 1055 free(signature); 1056 1057 /* skip session id and packet type */ 1058 if (buffer_len(&b) < skip + 1) 1059 fatal("userauth_pubkey: internal error"); 1060 buffer_consume(&b, skip + 1); 1061 1062 /* put remaining data from buffer into packet */ 1063 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1064 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1065 buffer_free(&b); 1066 packet_send(); 1067 1068 return 1; 1069} 1070 1071static int 1072send_pubkey_test(Authctxt *authctxt, Identity *id) 1073{ 1074 u_char *blob; 1075 u_int bloblen, have_sig = 0; 1076 1077 debug3("send_pubkey_test"); 1078 1079 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1080 /* we cannot handle this key */ 1081 debug3("send_pubkey_test: cannot handle key"); 1082 return 0; 1083 } 1084 /* register callback for USERAUTH_PK_OK message */ 1085 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1086 1087 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1088 packet_put_cstring(authctxt->server_user); 1089 packet_put_cstring(authctxt->service); 1090 packet_put_cstring(authctxt->method->name); 1091 packet_put_char(have_sig); 1092 if (!(datafellows & SSH_BUG_PKAUTH)) 1093 packet_put_cstring(key_ssh_name(id->key)); 1094 packet_put_string(blob, bloblen); 1095 free(blob); 1096 packet_send(); 1097 return 1; 1098} 1099 1100static Key * 1101load_identity_file(char *filename, int userprovided) 1102{ 1103 Key *private; 1104 char prompt[300], *passphrase; 1105 int perm_ok = 0, quit, i; 1106 struct stat st; 1107 1108 if (stat(filename, &st) < 0) { 1109 (userprovided ? logit : debug3)("no such identity: %s: %s", 1110 filename, strerror(errno)); 1111 return NULL; 1112 } 1113 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1114 if (!perm_ok) { 1115 if (private != NULL) 1116 key_free(private); 1117 return NULL; 1118 } 1119 if (private == NULL) { 1120 if (options.batch_mode) 1121 return NULL; 1122 snprintf(prompt, sizeof prompt, 1123 "Enter passphrase for key '%.100s': ", filename); 1124 for (i = 0; i < options.number_of_password_prompts; i++) { 1125 passphrase = read_passphrase(prompt, 0); 1126 if (strcmp(passphrase, "") != 0) { 1127 private = key_load_private_type(KEY_UNSPEC, 1128 filename, passphrase, NULL, NULL); 1129 quit = 0; 1130 } else { 1131 debug2("no passphrase given, try next key"); 1132 quit = 1; 1133 } 1134 explicit_bzero(passphrase, strlen(passphrase)); 1135 free(passphrase); 1136 if (private != NULL || quit) 1137 break; 1138 debug2("bad passphrase given, try again..."); 1139 } 1140 } 1141 return private; 1142} 1143 1144/* 1145 * try keys in the following order: 1146 * 1. agent keys that are found in the config file 1147 * 2. other agent keys 1148 * 3. keys that are only listed in the config file 1149 */ 1150static void 1151pubkey_prepare(Authctxt *authctxt) 1152{ 1153 Identity *id, *id2, *tmp; 1154 Idlist agent, files, *preferred; 1155 Key *key; 1156 AuthenticationConnection *ac; 1157 char *comment; 1158 int i, found; 1159 1160 TAILQ_INIT(&agent); /* keys from the agent */ 1161 TAILQ_INIT(&files); /* keys from the config file */ 1162 preferred = &authctxt->keys; 1163 TAILQ_INIT(preferred); /* preferred order of keys */ 1164 1165 /* list of keys stored in the filesystem and PKCS#11 */ 1166 for (i = 0; i < options.num_identity_files; i++) { 1167 key = options.identity_keys[i]; 1168 if (key && key->type == KEY_RSA1) 1169 continue; 1170 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1171 continue; 1172 options.identity_keys[i] = NULL; 1173 id = xcalloc(1, sizeof(*id)); 1174 id->key = key; 1175 id->filename = xstrdup(options.identity_files[i]); 1176 id->userprovided = options.identity_file_userprovided[i]; 1177 TAILQ_INSERT_TAIL(&files, id, next); 1178 } 1179 /* Prefer PKCS11 keys that are explicitly listed */ 1180 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1181 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1182 continue; 1183 found = 0; 1184 TAILQ_FOREACH(id2, &files, next) { 1185 if (id2->key == NULL || 1186 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1187 continue; 1188 if (key_equal(id->key, id2->key)) { 1189 TAILQ_REMOVE(&files, id, next); 1190 TAILQ_INSERT_TAIL(preferred, id, next); 1191 found = 1; 1192 break; 1193 } 1194 } 1195 /* If IdentitiesOnly set and key not found then don't use it */ 1196 if (!found && options.identities_only) { 1197 TAILQ_REMOVE(&files, id, next); 1198 explicit_bzero(id, sizeof(*id)); 1199 free(id); 1200 } 1201 } 1202 /* list of keys supported by the agent */ 1203 if ((ac = ssh_get_authentication_connection())) { 1204 for (key = ssh_get_first_identity(ac, &comment, 2); 1205 key != NULL; 1206 key = ssh_get_next_identity(ac, &comment, 2)) { 1207 found = 0; 1208 TAILQ_FOREACH(id, &files, next) { 1209 /* agent keys from the config file are preferred */ 1210 if (key_equal(key, id->key)) { 1211 key_free(key); 1212 free(comment); 1213 TAILQ_REMOVE(&files, id, next); 1214 TAILQ_INSERT_TAIL(preferred, id, next); 1215 id->ac = ac; 1216 found = 1; 1217 break; 1218 } 1219 } 1220 if (!found && !options.identities_only) { 1221 id = xcalloc(1, sizeof(*id)); 1222 id->key = key; 1223 id->filename = comment; 1224 id->ac = ac; 1225 TAILQ_INSERT_TAIL(&agent, id, next); 1226 } 1227 } 1228 /* append remaining agent keys */ 1229 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1230 TAILQ_REMOVE(&agent, id, next); 1231 TAILQ_INSERT_TAIL(preferred, id, next); 1232 } 1233 authctxt->agent = ac; 1234 } 1235 /* append remaining keys from the config file */ 1236 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1237 TAILQ_REMOVE(&files, id, next); 1238 TAILQ_INSERT_TAIL(preferred, id, next); 1239 } 1240 TAILQ_FOREACH(id, preferred, next) { 1241 debug2("key: %s (%p),%s", id->filename, id->key, 1242 id->userprovided ? " explicit" : ""); 1243 } 1244} 1245 1246static void 1247pubkey_cleanup(Authctxt *authctxt) 1248{ 1249 Identity *id; 1250 1251 if (authctxt->agent != NULL) 1252 ssh_close_authentication_connection(authctxt->agent); 1253 for (id = TAILQ_FIRST(&authctxt->keys); id; 1254 id = TAILQ_FIRST(&authctxt->keys)) { 1255 TAILQ_REMOVE(&authctxt->keys, id, next); 1256 if (id->key) 1257 key_free(id->key); 1258 free(id->filename); 1259 free(id); 1260 } 1261} 1262 1263int 1264userauth_pubkey(Authctxt *authctxt) 1265{ 1266 Identity *id; 1267 int sent = 0; 1268 1269 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1270 if (id->tried++) 1271 return (0); 1272 /* move key to the end of the queue */ 1273 TAILQ_REMOVE(&authctxt->keys, id, next); 1274 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1275 /* 1276 * send a test message if we have the public key. for 1277 * encrypted keys we cannot do this and have to load the 1278 * private key instead 1279 */ 1280 if (id->key != NULL) { 1281 if (key_type_plain(id->key->type) == KEY_RSA && 1282 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1283 debug("Skipped %s key %s for RSA/MD5 server", 1284 key_type(id->key), id->filename); 1285 } else if (id->key->type != KEY_RSA1) { 1286 debug("Offering %s public key: %s", 1287 key_type(id->key), id->filename); 1288 sent = send_pubkey_test(authctxt, id); 1289 } 1290 } else { 1291 debug("Trying private key: %s", id->filename); 1292 id->key = load_identity_file(id->filename, 1293 id->userprovided); 1294 if (id->key != NULL) { 1295 id->isprivate = 1; 1296 if (key_type_plain(id->key->type) == KEY_RSA && 1297 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1298 debug("Skipped %s key %s for RSA/MD5 " 1299 "server", key_type(id->key), 1300 id->filename); 1301 } else { 1302 sent = sign_and_send_pubkey( 1303 authctxt, id); 1304 } 1305 key_free(id->key); 1306 id->key = NULL; 1307 } 1308 } 1309 if (sent) 1310 return (sent); 1311 } 1312 return (0); 1313} 1314 1315/* 1316 * Send userauth request message specifying keyboard-interactive method. 1317 */ 1318int 1319userauth_kbdint(Authctxt *authctxt) 1320{ 1321 static int attempt = 0; 1322 1323 if (attempt++ >= options.number_of_password_prompts) 1324 return 0; 1325 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1326 if (attempt > 1 && !authctxt->info_req_seen) { 1327 debug3("userauth_kbdint: disable: no info_req_seen"); 1328 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1329 return 0; 1330 } 1331 1332 debug2("userauth_kbdint"); 1333 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1334 packet_put_cstring(authctxt->server_user); 1335 packet_put_cstring(authctxt->service); 1336 packet_put_cstring(authctxt->method->name); 1337 packet_put_cstring(""); /* lang */ 1338 packet_put_cstring(options.kbd_interactive_devices ? 1339 options.kbd_interactive_devices : ""); 1340 packet_send(); 1341 1342 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1343 return 1; 1344} 1345 1346/* 1347 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1348 */ 1349void 1350input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1351{ 1352 Authctxt *authctxt = ctxt; 1353 char *name, *inst, *lang, *prompt, *response; 1354 u_int num_prompts, i; 1355 int echo = 0; 1356 1357 debug2("input_userauth_info_req"); 1358 1359 if (authctxt == NULL) 1360 fatal("input_userauth_info_req: no authentication context"); 1361 1362 authctxt->info_req_seen = 1; 1363 1364 name = packet_get_string(NULL); 1365 inst = packet_get_string(NULL); 1366 lang = packet_get_string(NULL); 1367 if (strlen(name) > 0) 1368 logit("%s", name); 1369 if (strlen(inst) > 0) 1370 logit("%s", inst); 1371 free(name); 1372 free(inst); 1373 free(lang); 1374 1375 num_prompts = packet_get_int(); 1376 /* 1377 * Begin to build info response packet based on prompts requested. 1378 * We commit to providing the correct number of responses, so if 1379 * further on we run into a problem that prevents this, we have to 1380 * be sure and clean this up and send a correct error response. 1381 */ 1382 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1383 packet_put_int(num_prompts); 1384 1385 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1386 for (i = 0; i < num_prompts; i++) { 1387 prompt = packet_get_string(NULL); 1388 echo = packet_get_char(); 1389 1390 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1391 1392 packet_put_cstring(response); 1393 explicit_bzero(response, strlen(response)); 1394 free(response); 1395 free(prompt); 1396 } 1397 packet_check_eom(); /* done with parsing incoming message. */ 1398 1399 packet_add_padding(64); 1400 packet_send(); 1401} 1402 1403static int 1404ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1405 u_char *data, u_int datalen) 1406{ 1407 Buffer b; 1408 struct stat st; 1409 pid_t pid; 1410 int to[2], from[2], status, version = 2; 1411 1412 debug2("ssh_keysign called"); 1413 1414 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1415 error("ssh_keysign: not installed: %s", strerror(errno)); 1416 return -1; 1417 } 1418 if (fflush(stdout) != 0) 1419 error("ssh_keysign: fflush: %s", strerror(errno)); 1420 if (pipe(to) < 0) { 1421 error("ssh_keysign: pipe: %s", strerror(errno)); 1422 return -1; 1423 } 1424 if (pipe(from) < 0) { 1425 error("ssh_keysign: pipe: %s", strerror(errno)); 1426 return -1; 1427 } 1428 if ((pid = fork()) < 0) { 1429 error("ssh_keysign: fork: %s", strerror(errno)); 1430 return -1; 1431 } 1432 if (pid == 0) { 1433 /* keep the socket on exec */ 1434 fcntl(packet_get_connection_in(), F_SETFD, 0); 1435 permanently_drop_suid(getuid()); 1436 close(from[0]); 1437 if (dup2(from[1], STDOUT_FILENO) < 0) 1438 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1439 close(to[1]); 1440 if (dup2(to[0], STDIN_FILENO) < 0) 1441 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1442 close(from[1]); 1443 close(to[0]); 1444 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1445 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1446 strerror(errno)); 1447 } 1448 close(from[1]); 1449 close(to[0]); 1450 1451 buffer_init(&b); 1452 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1453 buffer_put_string(&b, data, datalen); 1454 if (ssh_msg_send(to[1], version, &b) == -1) 1455 fatal("ssh_keysign: couldn't send request"); 1456 1457 if (ssh_msg_recv(from[0], &b) < 0) { 1458 error("ssh_keysign: no reply"); 1459 buffer_free(&b); 1460 return -1; 1461 } 1462 close(from[0]); 1463 close(to[1]); 1464 1465 while (waitpid(pid, &status, 0) < 0) 1466 if (errno != EINTR) 1467 break; 1468 1469 if (buffer_get_char(&b) != version) { 1470 error("ssh_keysign: bad version"); 1471 buffer_free(&b); 1472 return -1; 1473 } 1474 *sigp = buffer_get_string(&b, lenp); 1475 buffer_free(&b); 1476 1477 return 0; 1478} 1479 1480int 1481userauth_hostbased(Authctxt *authctxt) 1482{ 1483 Key *private = NULL; 1484 Sensitive *sensitive = authctxt->sensitive; 1485 Buffer b; 1486 u_char *signature, *blob; 1487 char *chost, *pkalg, *p; 1488 const char *service; 1489 u_int blen, slen; 1490 int ok, i, found = 0; 1491 1492 /* check for a useful key */ 1493 for (i = 0; i < sensitive->nkeys; i++) { 1494 private = sensitive->keys[i]; 1495 if (private && private->type != KEY_RSA1) { 1496 found = 1; 1497 /* we take and free the key */ 1498 sensitive->keys[i] = NULL; 1499 break; 1500 } 1501 } 1502 if (!found) { 1503 debug("No more client hostkeys for hostbased authentication."); 1504 return 0; 1505 } 1506 if (key_to_blob(private, &blob, &blen) == 0) { 1507 key_free(private); 1508 return 0; 1509 } 1510 /* figure out a name for the client host */ 1511 p = get_local_name(packet_get_connection_in()); 1512 if (p == NULL) { 1513 error("userauth_hostbased: cannot get local ipaddr/name"); 1514 key_free(private); 1515 free(blob); 1516 return 0; 1517 } 1518 xasprintf(&chost, "%s.", p); 1519 debug2("userauth_hostbased: chost %s", chost); 1520 free(p); 1521 1522 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1523 authctxt->service; 1524 pkalg = xstrdup(key_ssh_name(private)); 1525 buffer_init(&b); 1526 /* construct data */ 1527 buffer_put_string(&b, session_id2, session_id2_len); 1528 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1529 buffer_put_cstring(&b, authctxt->server_user); 1530 buffer_put_cstring(&b, service); 1531 buffer_put_cstring(&b, authctxt->method->name); 1532 buffer_put_cstring(&b, pkalg); 1533 buffer_put_string(&b, blob, blen); 1534 buffer_put_cstring(&b, chost); 1535 buffer_put_cstring(&b, authctxt->local_user); 1536#ifdef DEBUG_PK 1537 buffer_dump(&b); 1538#endif 1539 if (sensitive->external_keysign) 1540 ok = ssh_keysign(private, &signature, &slen, 1541 buffer_ptr(&b), buffer_len(&b)); 1542 else 1543 ok = key_sign(private, &signature, &slen, 1544 buffer_ptr(&b), buffer_len(&b)); 1545 key_free(private); 1546 buffer_free(&b); 1547 if (ok != 0) { 1548 error("key_sign failed"); 1549 free(chost); 1550 free(pkalg); 1551 free(blob); 1552 return 0; 1553 } 1554 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1555 packet_put_cstring(authctxt->server_user); 1556 packet_put_cstring(authctxt->service); 1557 packet_put_cstring(authctxt->method->name); 1558 packet_put_cstring(pkalg); 1559 packet_put_string(blob, blen); 1560 packet_put_cstring(chost); 1561 packet_put_cstring(authctxt->local_user); 1562 packet_put_string(signature, slen); 1563 explicit_bzero(signature, slen); 1564 free(signature); 1565 free(chost); 1566 free(pkalg); 1567 free(blob); 1568 1569 packet_send(); 1570 return 1; 1571} 1572 1573/* find auth method */ 1574 1575/* 1576 * given auth method name, if configurable options permit this method fill 1577 * in auth_ident field and return true, otherwise return false. 1578 */ 1579static int 1580authmethod_is_enabled(Authmethod *method) 1581{ 1582 if (method == NULL) 1583 return 0; 1584 /* return false if options indicate this method is disabled */ 1585 if (method->enabled == NULL || *method->enabled == 0) 1586 return 0; 1587 /* return false if batch mode is enabled but method needs interactive mode */ 1588 if (method->batch_flag != NULL && *method->batch_flag != 0) 1589 return 0; 1590 return 1; 1591} 1592 1593static Authmethod * 1594authmethod_lookup(const char *name) 1595{ 1596 Authmethod *method = NULL; 1597 if (name != NULL) 1598 for (method = authmethods; method->name != NULL; method++) 1599 if (strcmp(name, method->name) == 0) 1600 return method; 1601 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1602 return NULL; 1603} 1604 1605/* XXX internal state */ 1606static Authmethod *current = NULL; 1607static char *supported = NULL; 1608static char *preferred = NULL; 1609 1610/* 1611 * Given the authentication method list sent by the server, return the 1612 * next method we should try. If the server initially sends a nil list, 1613 * use a built-in default list. 1614 */ 1615static Authmethod * 1616authmethod_get(char *authlist) 1617{ 1618 char *name = NULL; 1619 u_int next; 1620 1621 /* Use a suitable default if we're passed a nil list. */ 1622 if (authlist == NULL || strlen(authlist) == 0) 1623 authlist = options.preferred_authentications; 1624 1625 if (supported == NULL || strcmp(authlist, supported) != 0) { 1626 debug3("start over, passed a different list %s", authlist); 1627 free(supported); 1628 supported = xstrdup(authlist); 1629 preferred = options.preferred_authentications; 1630 debug3("preferred %s", preferred); 1631 current = NULL; 1632 } else if (current != NULL && authmethod_is_enabled(current)) 1633 return current; 1634 1635 for (;;) { 1636 if ((name = match_list(preferred, supported, &next)) == NULL) { 1637 debug("No more authentication methods to try."); 1638 current = NULL; 1639 return NULL; 1640 } 1641 preferred += next; 1642 debug3("authmethod_lookup %s", name); 1643 debug3("remaining preferred: %s", preferred); 1644 if ((current = authmethod_lookup(name)) != NULL && 1645 authmethod_is_enabled(current)) { 1646 debug3("authmethod_is_enabled %s", name); 1647 debug("Next authentication method: %s", name); 1648 free(name); 1649 return current; 1650 } 1651 free(name); 1652 } 1653} 1654 1655static char * 1656authmethods_get(void) 1657{ 1658 Authmethod *method = NULL; 1659 Buffer b; 1660 char *list; 1661 1662 buffer_init(&b); 1663 for (method = authmethods; method->name != NULL; method++) { 1664 if (authmethod_is_enabled(method)) { 1665 if (buffer_len(&b) > 0) 1666 buffer_append(&b, ",", 1); 1667 buffer_append(&b, method->name, strlen(method->name)); 1668 } 1669 } 1670 buffer_append(&b, "\0", 1); 1671 list = xstrdup(buffer_ptr(&b)); 1672 buffer_free(&b); 1673 return list; 1674} 1675 1676