1 /* $OpenBSD: sshconnect2.c,v 1.183 2010/04/26 22:28:24 djm 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) 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 "readconf.h" 65 #include "misc.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 "schnorr.h" 73 #include "jpake.h" 74 75 #ifdef GSSAPI 76 #include "ssh-gss.h" 77 #endif 78 79 /* import */ 80 extern char *client_version_string; 81 extern char *server_version_string; 82 extern Options options; 83 extern Kex *xxx_kex; 84 85 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */ 86 /* if it is set then prevent the switch to the null cipher */ 87 88 extern int tty_flag; 89 90 /* 91 * SSH2 key exchange 92 */ 93 94 u_char *session_id2 = NULL; 95 u_int session_id2_len = 0; 96 97 char *xxx_host; 98 struct sockaddr *xxx_hostaddr; 99 100 Kex *xxx_kex = NULL; 101 102 static int 103 verify_host_key_callback(Key *hostkey) 104 { 105 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 106 fatal("Host key verification failed."); 107 return 0; 108 } 109 110 void 111 ssh_kex2(char *host, struct sockaddr *hostaddr) 112 { 113 Kex *kex; 114 115 xxx_host = host; 116 xxx_hostaddr = hostaddr; 117 118 if (options.ciphers == (char *)-1) { 119 logit("No valid ciphers for protocol version 2 given, using defaults."); 120 options.ciphers = NULL; 121 } 122 if (options.ciphers != NULL) { 123 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 124 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 125 } 126 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 127 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 128 myproposal[PROPOSAL_ENC_ALGS_STOC] = 129 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 130 if (options.compression) { 131 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 132 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 133 } else { 134 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 135 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 136 } 137 if (options.macs != NULL) { 138 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 139 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 140 } 141 if (options.hostkeyalgorithms != NULL) 142 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 143 options.hostkeyalgorithms; 144 145 if (options.rekey_limit) 146 packet_set_rekey_limit((u_int32_t)options.rekey_limit); 147 148 /* start key exchange */ 149 kex = kex_setup(myproposal); 150 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 151 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 152 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 153 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 154 kex->client_version_string=client_version_string; 155 kex->server_version_string=server_version_string; 156 kex->verify_host_key=&verify_host_key_callback; 157 158 xxx_kex = kex; 159 160 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 161 162 if (options.use_roaming && !kex->roaming) { 163 debug("Roaming not allowed by server"); 164 options.use_roaming = 0; 165 } 166 167 session_id2 = kex->session_id; 168 session_id2_len = kex->session_id_len; 169 170 #ifdef DEBUG_KEXDH 171 /* send 1st encrypted/maced/compressed message */ 172 packet_start(SSH2_MSG_IGNORE); 173 packet_put_cstring("markus"); 174 packet_send(); 175 packet_write_wait(); 176 #endif 177 } 178 179 /* 180 * Authenticate user 181 */ 182 183 typedef struct Authctxt Authctxt; 184 typedef struct Authmethod Authmethod; 185 typedef struct identity Identity; 186 typedef struct idlist Idlist; 187 188 struct identity { 189 TAILQ_ENTRY(identity) next; 190 AuthenticationConnection *ac; /* set if agent supports key */ 191 Key *key; /* public/private key */ 192 char *filename; /* comment for agent-only keys */ 193 int tried; 194 int isprivate; /* key points to the private key */ 195 }; 196 TAILQ_HEAD(idlist, identity); 197 198 struct Authctxt { 199 const char *server_user; 200 const char *local_user; 201 const char *host; 202 const char *service; 203 Authmethod *method; 204 sig_atomic_t success; 205 char *authlist; 206 /* pubkey */ 207 Idlist keys; 208 AuthenticationConnection *agent; 209 /* hostbased */ 210 Sensitive *sensitive; 211 /* kbd-interactive */ 212 int info_req_seen; 213 /* generic */ 214 void *methoddata; 215 }; 216 struct Authmethod { 217 char *name; /* string to compare against server's list */ 218 int (*userauth)(Authctxt *authctxt); 219 void (*cleanup)(Authctxt *authctxt); 220 int *enabled; /* flag in option struct that enables method */ 221 int *batch_flag; /* flag in option struct that disables method */ 222 }; 223 224 void input_userauth_success(int, u_int32_t, void *); 225 void input_userauth_success_unexpected(int, u_int32_t, void *); 226 void input_userauth_failure(int, u_int32_t, void *); 227 void input_userauth_banner(int, u_int32_t, void *); 228 void input_userauth_error(int, u_int32_t, void *); 229 void input_userauth_info_req(int, u_int32_t, void *); 230 void input_userauth_pk_ok(int, u_int32_t, void *); 231 void input_userauth_passwd_changereq(int, u_int32_t, void *); 232 void input_userauth_jpake_server_step1(int, u_int32_t, void *); 233 void input_userauth_jpake_server_step2(int, u_int32_t, void *); 234 void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 235 236 int userauth_none(Authctxt *); 237 int userauth_pubkey(Authctxt *); 238 int userauth_passwd(Authctxt *); 239 int userauth_kbdint(Authctxt *); 240 int userauth_hostbased(Authctxt *); 241 int userauth_jpake(Authctxt *); 242 243 void userauth_jpake_cleanup(Authctxt *); 244 245 #ifdef GSSAPI 246 int userauth_gssapi(Authctxt *authctxt); 247 void input_gssapi_response(int type, u_int32_t, void *); 248 void input_gssapi_token(int type, u_int32_t, void *); 249 void input_gssapi_hash(int type, u_int32_t, void *); 250 void input_gssapi_error(int, u_int32_t, void *); 251 void input_gssapi_errtok(int, u_int32_t, void *); 252 #endif 253 254 void userauth(Authctxt *, char *); 255 256 static int sign_and_send_pubkey(Authctxt *, Identity *); 257 static void pubkey_prepare(Authctxt *); 258 static void pubkey_cleanup(Authctxt *); 259 static Key *load_identity_file(char *); 260 261 static Authmethod *authmethod_get(char *authlist); 262 static Authmethod *authmethod_lookup(const char *name); 263 static char *authmethods_get(void); 264 265 Authmethod authmethods[] = { 266 #ifdef GSSAPI 267 {"gssapi-with-mic", 268 userauth_gssapi, 269 NULL, 270 &options.gss_authentication, 271 NULL}, 272 #endif 273 {"hostbased", 274 userauth_hostbased, 275 NULL, 276 &options.hostbased_authentication, 277 NULL}, 278 {"publickey", 279 userauth_pubkey, 280 NULL, 281 &options.pubkey_authentication, 282 NULL}, 283 #ifdef JPAKE 284 {"jpake-01@openssh.com", 285 userauth_jpake, 286 userauth_jpake_cleanup, 287 &options.zero_knowledge_password_authentication, 288 &options.batch_mode}, 289 #endif 290 {"keyboard-interactive", 291 userauth_kbdint, 292 NULL, 293 &options.kbd_interactive_authentication, 294 &options.batch_mode}, 295 {"password", 296 userauth_passwd, 297 NULL, 298 &options.password_authentication, 299 &options.batch_mode}, 300 {"none", 301 userauth_none, 302 NULL, 303 NULL, 304 NULL}, 305 {NULL, NULL, NULL, NULL, NULL} 306 }; 307 308 void 309 ssh_userauth2(const char *local_user, const char *server_user, char *host, 310 Sensitive *sensitive) 311 { 312 Authctxt authctxt; 313 int type; 314 315 if (options.challenge_response_authentication) 316 options.kbd_interactive_authentication = 1; 317 318 packet_start(SSH2_MSG_SERVICE_REQUEST); 319 packet_put_cstring("ssh-userauth"); 320 packet_send(); 321 debug("SSH2_MSG_SERVICE_REQUEST sent"); 322 packet_write_wait(); 323 type = packet_read(); 324 if (type != SSH2_MSG_SERVICE_ACCEPT) 325 fatal("Server denied authentication request: %d", type); 326 if (packet_remaining() > 0) { 327 char *reply = packet_get_string(NULL); 328 debug2("service_accept: %s", reply); 329 xfree(reply); 330 } else { 331 debug2("buggy server: service_accept w/o service"); 332 } 333 packet_check_eom(); 334 debug("SSH2_MSG_SERVICE_ACCEPT received"); 335 336 if (options.preferred_authentications == NULL) 337 options.preferred_authentications = authmethods_get(); 338 339 /* setup authentication context */ 340 memset(&authctxt, 0, sizeof(authctxt)); 341 pubkey_prepare(&authctxt); 342 authctxt.server_user = server_user; 343 authctxt.local_user = local_user; 344 authctxt.host = host; 345 authctxt.service = "ssh-connection"; /* service name */ 346 authctxt.success = 0; 347 authctxt.method = authmethod_lookup("none"); 348 authctxt.authlist = NULL; 349 authctxt.methoddata = NULL; 350 authctxt.sensitive = sensitive; 351 authctxt.info_req_seen = 0; 352 if (authctxt.method == NULL) 353 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 354 355 /* initial userauth request */ 356 userauth_none(&authctxt); 357 358 dispatch_init(&input_userauth_error); 359 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 360 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 361 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 362 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 363 364 pubkey_cleanup(&authctxt); 365 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 366 367 /* if the user wants to use the none cipher do it */ 368 /* post authentication and only if the right conditions are met */ 369 /* both of the NONE commands must be true and there must be no */ 370 /* tty allocated */ 371 if ((options.none_switch == 1) && (options.none_enabled == 1)) 372 { 373 if (!tty_flag) /* no null on tty sessions */ 374 { 375 debug("Requesting none rekeying..."); 376 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 377 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 378 kex_prop2buf(&xxx_kex->my,myproposal); 379 packet_request_rekeying(); 380 fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n"); 381 } 382 else 383 { 384 /* requested NONE cipher when in a tty */ 385 debug("Cannot switch to NONE cipher with tty allocated"); 386 fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n"); 387 } 388 } 389 debug("Authentication succeeded (%s).", authctxt.method->name); 390 } 391 392 void 393 userauth(Authctxt *authctxt, char *authlist) 394 { 395 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 396 authctxt->method->cleanup(authctxt); 397 398 if (authctxt->methoddata) { 399 xfree(authctxt->methoddata); 400 authctxt->methoddata = NULL; 401 } 402 if (authlist == NULL) { 403 authlist = authctxt->authlist; 404 } else { 405 if (authctxt->authlist) 406 xfree(authctxt->authlist); 407 authctxt->authlist = authlist; 408 } 409 for (;;) { 410 Authmethod *method = authmethod_get(authlist); 411 if (method == NULL) 412 fatal("Permission denied (%s).", authlist); 413 authctxt->method = method; 414 415 /* reset the per method handler */ 416 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 417 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 418 419 /* and try new method */ 420 if (method->userauth(authctxt) != 0) { 421 debug2("we sent a %s packet, wait for reply", method->name); 422 break; 423 } else { 424 debug2("we did not send a packet, disable method"); 425 method->enabled = NULL; 426 } 427 } 428 } 429 430 /* ARGSUSED */ 431 void 432 input_userauth_error(int type, u_int32_t seq, void *ctxt) 433 { 434 fatal("input_userauth_error: bad message during authentication: " 435 "type %d", type); 436 } 437 438 /* ARGSUSED */ 439 void 440 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 441 { 442 char *msg, *raw, *lang; 443 u_int len; 444 445 debug3("input_userauth_banner"); 446 raw = packet_get_string(&len); 447 lang = packet_get_string(NULL); 448 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 449 if (len > 65536) 450 len = 65536; 451 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 452 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 453 fprintf(stderr, "%s", msg); 454 xfree(msg); 455 } 456 xfree(raw); 457 xfree(lang); 458 } 459 460 /* ARGSUSED */ 461 void 462 input_userauth_success(int type, u_int32_t seq, void *ctxt) 463 { 464 Authctxt *authctxt = ctxt; 465 466 if (authctxt == NULL) 467 fatal("input_userauth_success: no authentication context"); 468 if (authctxt->authlist) { 469 xfree(authctxt->authlist); 470 authctxt->authlist = NULL; 471 } 472 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 473 authctxt->method->cleanup(authctxt); 474 if (authctxt->methoddata) { 475 xfree(authctxt->methoddata); 476 authctxt->methoddata = NULL; 477 } 478 authctxt->success = 1; /* break out */ 479 } 480 481 void 482 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 483 { 484 Authctxt *authctxt = ctxt; 485 486 if (authctxt == NULL) 487 fatal("%s: no authentication context", __func__); 488 489 fatal("Unexpected authentication success during %s.", 490 authctxt->method->name); 491 } 492 493 /* ARGSUSED */ 494 void 495 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 496 { 497 Authctxt *authctxt = ctxt; 498 char *authlist = NULL; 499 int partial; 500 501 if (authctxt == NULL) 502 fatal("input_userauth_failure: no authentication context"); 503 504 authlist = packet_get_string(NULL); 505 partial = packet_get_char(); 506 packet_check_eom(); 507 508 if (partial != 0) 509 logit("Authenticated with partial success."); 510 debug("Authentications that can continue: %s", authlist); 511 512 userauth(authctxt, authlist); 513 } 514 515 /* ARGSUSED */ 516 void 517 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 518 { 519 Authctxt *authctxt = ctxt; 520 Key *key = NULL; 521 Identity *id = NULL; 522 Buffer b; 523 int pktype, sent = 0; 524 u_int alen, blen; 525 char *pkalg, *fp; 526 u_char *pkblob; 527 528 if (authctxt == NULL) 529 fatal("input_userauth_pk_ok: no authentication context"); 530 if (datafellows & SSH_BUG_PKOK) { 531 /* this is similar to SSH_BUG_PKAUTH */ 532 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 533 pkblob = packet_get_string(&blen); 534 buffer_init(&b); 535 buffer_append(&b, pkblob, blen); 536 pkalg = buffer_get_string(&b, &alen); 537 buffer_free(&b); 538 } else { 539 pkalg = packet_get_string(&alen); 540 pkblob = packet_get_string(&blen); 541 } 542 packet_check_eom(); 543 544 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 545 546 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 547 debug("unknown pkalg %s", pkalg); 548 goto done; 549 } 550 if ((key = key_from_blob(pkblob, blen)) == NULL) { 551 debug("no key from blob. pkalg %s", pkalg); 552 goto done; 553 } 554 if (key->type != pktype) { 555 error("input_userauth_pk_ok: type mismatch " 556 "for decoded key (received %d, expected %d)", 557 key->type, pktype); 558 goto done; 559 } 560 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 561 debug2("input_userauth_pk_ok: fp %s", fp); 562 xfree(fp); 563 564 /* 565 * search keys in the reverse order, because last candidate has been 566 * moved to the end of the queue. this also avoids confusion by 567 * duplicate keys 568 */ 569 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 570 if (key_equal(key, id->key)) { 571 sent = sign_and_send_pubkey(authctxt, id); 572 break; 573 } 574 } 575 done: 576 if (key != NULL) 577 key_free(key); 578 xfree(pkalg); 579 xfree(pkblob); 580 581 /* try another method if we did not send a packet */ 582 if (sent == 0) 583 userauth(authctxt, NULL); 584 } 585 586 #ifdef GSSAPI 587 int 588 userauth_gssapi(Authctxt *authctxt) 589 { 590 Gssctxt *gssctxt = NULL; 591 static gss_OID_set gss_supported = NULL; 592 static u_int mech = 0; 593 OM_uint32 min; 594 int ok = 0; 595 596 /* Try one GSSAPI method at a time, rather than sending them all at 597 * once. */ 598 599 if (gss_supported == NULL) 600 gss_indicate_mechs(&min, &gss_supported); 601 602 /* Check to see if the mechanism is usable before we offer it */ 603 while (mech < gss_supported->count && !ok) { 604 /* My DER encoding requires length<128 */ 605 if (gss_supported->elements[mech].length < 128 && 606 ssh_gssapi_check_mechanism(&gssctxt, 607 &gss_supported->elements[mech], authctxt->host)) { 608 ok = 1; /* Mechanism works */ 609 } else { 610 mech++; 611 } 612 } 613 614 if (!ok) 615 return 0; 616 617 authctxt->methoddata=(void *)gssctxt; 618 619 packet_start(SSH2_MSG_USERAUTH_REQUEST); 620 packet_put_cstring(authctxt->server_user); 621 packet_put_cstring(authctxt->service); 622 packet_put_cstring(authctxt->method->name); 623 624 packet_put_int(1); 625 626 packet_put_int((gss_supported->elements[mech].length) + 2); 627 packet_put_char(SSH_GSS_OIDTYPE); 628 packet_put_char(gss_supported->elements[mech].length); 629 packet_put_raw(gss_supported->elements[mech].elements, 630 gss_supported->elements[mech].length); 631 632 packet_send(); 633 634 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 635 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 636 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 637 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 638 639 mech++; /* Move along to next candidate */ 640 641 return 1; 642 } 643 644 static OM_uint32 645 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 646 { 647 Authctxt *authctxt = ctxt; 648 Gssctxt *gssctxt = authctxt->methoddata; 649 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 650 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 651 gss_buffer_desc gssbuf; 652 OM_uint32 status, ms, flags; 653 Buffer b; 654 655 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 656 recv_tok, &send_tok, &flags); 657 658 if (send_tok.length > 0) { 659 if (GSS_ERROR(status)) 660 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 661 else 662 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 663 664 packet_put_string(send_tok.value, send_tok.length); 665 packet_send(); 666 gss_release_buffer(&ms, &send_tok); 667 } 668 669 if (status == GSS_S_COMPLETE) { 670 /* send either complete or MIC, depending on mechanism */ 671 if (!(flags & GSS_C_INTEG_FLAG)) { 672 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 673 packet_send(); 674 } else { 675 ssh_gssapi_buildmic(&b, authctxt->server_user, 676 authctxt->service, "gssapi-with-mic"); 677 678 gssbuf.value = buffer_ptr(&b); 679 gssbuf.length = buffer_len(&b); 680 681 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 682 683 if (!GSS_ERROR(status)) { 684 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 685 packet_put_string(mic.value, mic.length); 686 687 packet_send(); 688 } 689 690 buffer_free(&b); 691 gss_release_buffer(&ms, &mic); 692 } 693 } 694 695 return status; 696 } 697 698 /* ARGSUSED */ 699 void 700 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 701 { 702 Authctxt *authctxt = ctxt; 703 Gssctxt *gssctxt; 704 int oidlen; 705 char *oidv; 706 707 if (authctxt == NULL) 708 fatal("input_gssapi_response: no authentication context"); 709 gssctxt = authctxt->methoddata; 710 711 /* Setup our OID */ 712 oidv = packet_get_string(&oidlen); 713 714 if (oidlen <= 2 || 715 oidv[0] != SSH_GSS_OIDTYPE || 716 oidv[1] != oidlen - 2) { 717 xfree(oidv); 718 debug("Badly encoded mechanism OID received"); 719 userauth(authctxt, NULL); 720 return; 721 } 722 723 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 724 fatal("Server returned different OID than expected"); 725 726 packet_check_eom(); 727 728 xfree(oidv); 729 730 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 731 /* Start again with next method on list */ 732 debug("Trying to start again"); 733 userauth(authctxt, NULL); 734 return; 735 } 736 } 737 738 /* ARGSUSED */ 739 void 740 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 741 { 742 Authctxt *authctxt = ctxt; 743 gss_buffer_desc recv_tok; 744 OM_uint32 status; 745 u_int slen; 746 747 if (authctxt == NULL) 748 fatal("input_gssapi_response: no authentication context"); 749 750 recv_tok.value = packet_get_string(&slen); 751 recv_tok.length = slen; /* safe typecast */ 752 753 packet_check_eom(); 754 755 status = process_gssapi_token(ctxt, &recv_tok); 756 757 xfree(recv_tok.value); 758 759 if (GSS_ERROR(status)) { 760 /* Start again with the next method in the list */ 761 userauth(authctxt, NULL); 762 return; 763 } 764 } 765 766 /* ARGSUSED */ 767 void 768 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 769 { 770 Authctxt *authctxt = ctxt; 771 Gssctxt *gssctxt; 772 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 773 gss_buffer_desc recv_tok; 774 OM_uint32 status, ms; 775 u_int len; 776 777 if (authctxt == NULL) 778 fatal("input_gssapi_response: no authentication context"); 779 gssctxt = authctxt->methoddata; 780 781 recv_tok.value = packet_get_string(&len); 782 recv_tok.length = len; 783 784 packet_check_eom(); 785 786 /* Stick it into GSSAPI and see what it says */ 787 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 788 &recv_tok, &send_tok, NULL); 789 790 xfree(recv_tok.value); 791 gss_release_buffer(&ms, &send_tok); 792 793 /* Server will be returning a failed packet after this one */ 794 } 795 796 /* ARGSUSED */ 797 void 798 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 799 { 800 OM_uint32 maj, min; 801 char *msg; 802 char *lang; 803 804 maj=packet_get_int(); 805 min=packet_get_int(); 806 msg=packet_get_string(NULL); 807 lang=packet_get_string(NULL); 808 809 packet_check_eom(); 810 811 debug("Server GSSAPI Error:\n%s", msg); 812 xfree(msg); 813 xfree(lang); 814 } 815 #endif /* GSSAPI */ 816 817 int 818 userauth_none(Authctxt *authctxt) 819 { 820 /* initial userauth request */ 821 packet_start(SSH2_MSG_USERAUTH_REQUEST); 822 packet_put_cstring(authctxt->server_user); 823 packet_put_cstring(authctxt->service); 824 packet_put_cstring(authctxt->method->name); 825 packet_send(); 826 return 1; 827 } 828 829 int 830 userauth_passwd(Authctxt *authctxt) 831 { 832 static int attempt = 0; 833 char prompt[150]; 834 char *password; 835 const char *host = options.host_key_alias ? options.host_key_alias : 836 authctxt->host; 837 838 if (attempt++ >= options.number_of_password_prompts) 839 return 0; 840 841 if (attempt != 1) 842 error("Permission denied, please try again."); 843 844 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 845 authctxt->server_user, host); 846 password = read_passphrase(prompt, 0); 847 packet_start(SSH2_MSG_USERAUTH_REQUEST); 848 packet_put_cstring(authctxt->server_user); 849 packet_put_cstring(authctxt->service); 850 packet_put_cstring(authctxt->method->name); 851 packet_put_char(0); 852 packet_put_cstring(password); 853 memset(password, 0, strlen(password)); 854 xfree(password); 855 packet_add_padding(64); 856 packet_send(); 857 858 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 859 &input_userauth_passwd_changereq); 860 861 return 1; 862 } 863 864 /* 865 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 866 */ 867 /* ARGSUSED */ 868 void 869 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 870 { 871 Authctxt *authctxt = ctxt; 872 char *info, *lang, *password = NULL, *retype = NULL; 873 char prompt[150]; 874 const char *host = options.host_key_alias ? options.host_key_alias : 875 authctxt->host; 876 877 debug2("input_userauth_passwd_changereq"); 878 879 if (authctxt == NULL) 880 fatal("input_userauth_passwd_changereq: " 881 "no authentication context"); 882 883 info = packet_get_string(NULL); 884 lang = packet_get_string(NULL); 885 if (strlen(info) > 0) 886 logit("%s", info); 887 xfree(info); 888 xfree(lang); 889 packet_start(SSH2_MSG_USERAUTH_REQUEST); 890 packet_put_cstring(authctxt->server_user); 891 packet_put_cstring(authctxt->service); 892 packet_put_cstring(authctxt->method->name); 893 packet_put_char(1); /* additional info */ 894 snprintf(prompt, sizeof(prompt), 895 "Enter %.30s@%.128s's old password: ", 896 authctxt->server_user, host); 897 password = read_passphrase(prompt, 0); 898 packet_put_cstring(password); 899 memset(password, 0, strlen(password)); 900 xfree(password); 901 password = NULL; 902 while (password == NULL) { 903 snprintf(prompt, sizeof(prompt), 904 "Enter %.30s@%.128s's new password: ", 905 authctxt->server_user, host); 906 password = read_passphrase(prompt, RP_ALLOW_EOF); 907 if (password == NULL) { 908 /* bail out */ 909 return; 910 } 911 snprintf(prompt, sizeof(prompt), 912 "Retype %.30s@%.128s's new password: ", 913 authctxt->server_user, host); 914 retype = read_passphrase(prompt, 0); 915 if (strcmp(password, retype) != 0) { 916 memset(password, 0, strlen(password)); 917 xfree(password); 918 logit("Mismatch; try again, EOF to quit."); 919 password = NULL; 920 } 921 memset(retype, 0, strlen(retype)); 922 xfree(retype); 923 } 924 packet_put_cstring(password); 925 memset(password, 0, strlen(password)); 926 xfree(password); 927 packet_add_padding(64); 928 packet_send(); 929 930 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 931 &input_userauth_passwd_changereq); 932 } 933 934 #ifdef JPAKE 935 static char * 936 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 937 { 938 /* OpenBSD crypt(3) handles all of these */ 939 if (strcmp(crypt_scheme, "crypt") == 0 || 940 strcmp(crypt_scheme, "bcrypt") == 0 || 941 strcmp(crypt_scheme, "md5crypt") == 0 || 942 strcmp(crypt_scheme, "crypt-extended") == 0) 943 return xstrdup(crypt(password, salt)); 944 error("%s: unsupported password encryption scheme \"%.100s\"", 945 __func__, crypt_scheme); 946 return NULL; 947 } 948 949 static BIGNUM * 950 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 951 const char *salt) 952 { 953 char prompt[256], *password, *crypted; 954 u_char *secret; 955 u_int secret_len; 956 BIGNUM *ret; 957 958 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 959 authctxt->server_user, authctxt->host); 960 password = read_passphrase(prompt, 0); 961 962 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 963 logit("Disabling %s authentication", authctxt->method->name); 964 authctxt->method->enabled = NULL; 965 /* Continue with an empty password to fail gracefully */ 966 crypted = xstrdup(""); 967 } 968 969 #ifdef JPAKE_DEBUG 970 debug3("%s: salt = %s", __func__, salt); 971 debug3("%s: scheme = %s", __func__, crypt_scheme); 972 debug3("%s: crypted = %s", __func__, crypted); 973 #endif 974 975 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 976 &secret, &secret_len) != 0) 977 fatal("%s: hash_buffer", __func__); 978 979 bzero(password, strlen(password)); 980 bzero(crypted, strlen(crypted)); 981 xfree(password); 982 xfree(crypted); 983 984 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 985 fatal("%s: BN_bin2bn (secret)", __func__); 986 bzero(secret, secret_len); 987 xfree(secret); 988 989 return ret; 990 } 991 992 /* ARGSUSED */ 993 void 994 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 995 { 996 Authctxt *authctxt = ctxt; 997 struct jpake_ctx *pctx = authctxt->methoddata; 998 u_char *x3_proof, *x4_proof, *x2_s_proof; 999 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1000 char *crypt_scheme, *salt; 1001 1002 /* Disable this message */ 1003 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1004 1005 if ((pctx->g_x3 = BN_new()) == NULL || 1006 (pctx->g_x4 = BN_new()) == NULL) 1007 fatal("%s: BN_new", __func__); 1008 1009 /* Fetch step 1 values */ 1010 crypt_scheme = packet_get_string(NULL); 1011 salt = packet_get_string(NULL); 1012 pctx->server_id = packet_get_string(&pctx->server_id_len); 1013 packet_get_bignum2(pctx->g_x3); 1014 packet_get_bignum2(pctx->g_x4); 1015 x3_proof = packet_get_string(&x3_proof_len); 1016 x4_proof = packet_get_string(&x4_proof_len); 1017 packet_check_eom(); 1018 1019 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1020 1021 /* Obtain password and derive secret */ 1022 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1023 bzero(crypt_scheme, strlen(crypt_scheme)); 1024 bzero(salt, strlen(salt)); 1025 xfree(crypt_scheme); 1026 xfree(salt); 1027 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1028 1029 /* Calculate step 2 values */ 1030 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1031 pctx->g_x3, pctx->g_x4, pctx->x2, 1032 pctx->server_id, pctx->server_id_len, 1033 pctx->client_id, pctx->client_id_len, 1034 x3_proof, x3_proof_len, 1035 x4_proof, x4_proof_len, 1036 &pctx->a, 1037 &x2_s_proof, &x2_s_proof_len); 1038 1039 bzero(x3_proof, x3_proof_len); 1040 bzero(x4_proof, x4_proof_len); 1041 xfree(x3_proof); 1042 xfree(x4_proof); 1043 1044 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1045 1046 /* Send values for step 2 */ 1047 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1048 packet_put_bignum2(pctx->a); 1049 packet_put_string(x2_s_proof, x2_s_proof_len); 1050 packet_send(); 1051 1052 bzero(x2_s_proof, x2_s_proof_len); 1053 xfree(x2_s_proof); 1054 1055 /* Expect step 2 packet from peer */ 1056 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1057 input_userauth_jpake_server_step2); 1058 } 1059 1060 /* ARGSUSED */ 1061 void 1062 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1063 { 1064 Authctxt *authctxt = ctxt; 1065 struct jpake_ctx *pctx = authctxt->methoddata; 1066 u_char *x4_s_proof; 1067 u_int x4_s_proof_len; 1068 1069 /* Disable this message */ 1070 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1071 1072 if ((pctx->b = BN_new()) == NULL) 1073 fatal("%s: BN_new", __func__); 1074 1075 /* Fetch step 2 values */ 1076 packet_get_bignum2(pctx->b); 1077 x4_s_proof = packet_get_string(&x4_s_proof_len); 1078 packet_check_eom(); 1079 1080 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1081 1082 /* Derive shared key and calculate confirmation hash */ 1083 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1084 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1085 pctx->client_id, pctx->client_id_len, 1086 pctx->server_id, pctx->server_id_len, 1087 session_id2, session_id2_len, 1088 x4_s_proof, x4_s_proof_len, 1089 &pctx->k, 1090 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1091 1092 bzero(x4_s_proof, x4_s_proof_len); 1093 xfree(x4_s_proof); 1094 1095 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1096 1097 /* Send key confirmation proof */ 1098 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1099 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1100 packet_send(); 1101 1102 /* Expect confirmation from peer */ 1103 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1104 input_userauth_jpake_server_confirm); 1105 } 1106 1107 /* ARGSUSED */ 1108 void 1109 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1110 { 1111 Authctxt *authctxt = ctxt; 1112 struct jpake_ctx *pctx = authctxt->methoddata; 1113 1114 /* Disable this message */ 1115 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1116 1117 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1118 packet_check_eom(); 1119 1120 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1121 1122 /* Verify expected confirmation hash */ 1123 if (jpake_check_confirm(pctx->k, 1124 pctx->server_id, pctx->server_id_len, 1125 session_id2, session_id2_len, 1126 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1127 debug("%s: %s success", __func__, authctxt->method->name); 1128 else { 1129 debug("%s: confirmation mismatch", __func__); 1130 /* XXX stash this so if auth succeeds then we can warn/kill */ 1131 } 1132 1133 userauth_jpake_cleanup(authctxt); 1134 } 1135 #endif /* JPAKE */ 1136 1137 static int 1138 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1139 u_char *data, u_int datalen) 1140 { 1141 Key *prv; 1142 int ret; 1143 1144 /* the agent supports this key */ 1145 if (id->ac) 1146 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1147 data, datalen)); 1148 /* 1149 * we have already loaded the private key or 1150 * the private key is stored in external hardware 1151 */ 1152 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1153 return (key_sign(id->key, sigp, lenp, data, datalen)); 1154 /* load the private key from the file */ 1155 if ((prv = load_identity_file(id->filename)) == NULL) 1156 return (-1); 1157 ret = key_sign(prv, sigp, lenp, data, datalen); 1158 key_free(prv); 1159 return (ret); 1160 } 1161 1162 static int 1163 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1164 { 1165 Buffer b; 1166 u_char *blob, *signature; 1167 u_int bloblen, slen; 1168 u_int skip = 0; 1169 int ret = -1; 1170 int have_sig = 1; 1171 char *fp; 1172 1173 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1174 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1175 xfree(fp); 1176 1177 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1178 /* we cannot handle this key */ 1179 debug3("sign_and_send_pubkey: cannot handle key"); 1180 return 0; 1181 } 1182 /* data to be signed */ 1183 buffer_init(&b); 1184 if (datafellows & SSH_OLD_SESSIONID) { 1185 buffer_append(&b, session_id2, session_id2_len); 1186 skip = session_id2_len; 1187 } else { 1188 buffer_put_string(&b, session_id2, session_id2_len); 1189 skip = buffer_len(&b); 1190 } 1191 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1192 buffer_put_cstring(&b, authctxt->server_user); 1193 buffer_put_cstring(&b, 1194 datafellows & SSH_BUG_PKSERVICE ? 1195 "ssh-userauth" : 1196 authctxt->service); 1197 if (datafellows & SSH_BUG_PKAUTH) { 1198 buffer_put_char(&b, have_sig); 1199 } else { 1200 buffer_put_cstring(&b, authctxt->method->name); 1201 buffer_put_char(&b, have_sig); 1202 buffer_put_cstring(&b, key_ssh_name(id->key)); 1203 } 1204 buffer_put_string(&b, blob, bloblen); 1205 1206 /* generate signature */ 1207 ret = identity_sign(id, &signature, &slen, 1208 buffer_ptr(&b), buffer_len(&b)); 1209 if (ret == -1) { 1210 xfree(blob); 1211 buffer_free(&b); 1212 return 0; 1213 } 1214 #ifdef DEBUG_PK 1215 buffer_dump(&b); 1216 #endif 1217 if (datafellows & SSH_BUG_PKSERVICE) { 1218 buffer_clear(&b); 1219 buffer_append(&b, session_id2, session_id2_len); 1220 skip = session_id2_len; 1221 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1222 buffer_put_cstring(&b, authctxt->server_user); 1223 buffer_put_cstring(&b, authctxt->service); 1224 buffer_put_cstring(&b, authctxt->method->name); 1225 buffer_put_char(&b, have_sig); 1226 if (!(datafellows & SSH_BUG_PKAUTH)) 1227 buffer_put_cstring(&b, key_ssh_name(id->key)); 1228 buffer_put_string(&b, blob, bloblen); 1229 } 1230 xfree(blob); 1231 1232 /* append signature */ 1233 buffer_put_string(&b, signature, slen); 1234 xfree(signature); 1235 1236 /* skip session id and packet type */ 1237 if (buffer_len(&b) < skip + 1) 1238 fatal("userauth_pubkey: internal error"); 1239 buffer_consume(&b, skip + 1); 1240 1241 /* put remaining data from buffer into packet */ 1242 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1243 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1244 buffer_free(&b); 1245 packet_send(); 1246 1247 return 1; 1248 } 1249 1250 static int 1251 send_pubkey_test(Authctxt *authctxt, Identity *id) 1252 { 1253 u_char *blob; 1254 u_int bloblen, have_sig = 0; 1255 1256 debug3("send_pubkey_test"); 1257 1258 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1259 /* we cannot handle this key */ 1260 debug3("send_pubkey_test: cannot handle key"); 1261 return 0; 1262 } 1263 /* register callback for USERAUTH_PK_OK message */ 1264 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1265 1266 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1267 packet_put_cstring(authctxt->server_user); 1268 packet_put_cstring(authctxt->service); 1269 packet_put_cstring(authctxt->method->name); 1270 packet_put_char(have_sig); 1271 if (!(datafellows & SSH_BUG_PKAUTH)) 1272 packet_put_cstring(key_ssh_name(id->key)); 1273 packet_put_string(blob, bloblen); 1274 xfree(blob); 1275 packet_send(); 1276 return 1; 1277 } 1278 1279 static Key * 1280 load_identity_file(char *filename) 1281 { 1282 Key *private; 1283 char prompt[300], *passphrase; 1284 int perm_ok = 0, quit, i; 1285 struct stat st; 1286 1287 if (stat(filename, &st) < 0) { 1288 debug3("no such identity: %s", filename); 1289 return NULL; 1290 } 1291 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1292 if (!perm_ok) 1293 return NULL; 1294 if (private == NULL) { 1295 if (options.batch_mode) 1296 return NULL; 1297 snprintf(prompt, sizeof prompt, 1298 "Enter passphrase for key '%.100s': ", filename); 1299 for (i = 0; i < options.number_of_password_prompts; i++) { 1300 passphrase = read_passphrase(prompt, 0); 1301 if (strcmp(passphrase, "") != 0) { 1302 private = key_load_private_type(KEY_UNSPEC, 1303 filename, passphrase, NULL, NULL); 1304 quit = 0; 1305 } else { 1306 debug2("no passphrase given, try next key"); 1307 quit = 1; 1308 } 1309 memset(passphrase, 0, strlen(passphrase)); 1310 xfree(passphrase); 1311 if (private != NULL || quit) 1312 break; 1313 debug2("bad passphrase given, try again..."); 1314 } 1315 } 1316 return private; 1317 } 1318 1319 /* 1320 * try keys in the following order: 1321 * 1. agent keys that are found in the config file 1322 * 2. other agent keys 1323 * 3. keys that are only listed in the config file 1324 */ 1325 static void 1326 pubkey_prepare(Authctxt *authctxt) 1327 { 1328 Identity *id; 1329 Idlist agent, files, *preferred; 1330 Key *key; 1331 AuthenticationConnection *ac; 1332 char *comment; 1333 int i, found; 1334 1335 TAILQ_INIT(&agent); /* keys from the agent */ 1336 TAILQ_INIT(&files); /* keys from the config file */ 1337 preferred = &authctxt->keys; 1338 TAILQ_INIT(preferred); /* preferred order of keys */ 1339 1340 /* list of keys stored in the filesystem */ 1341 for (i = 0; i < options.num_identity_files; i++) { 1342 key = options.identity_keys[i]; 1343 if (key && key->type == KEY_RSA1) 1344 continue; 1345 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1346 continue; 1347 options.identity_keys[i] = NULL; 1348 id = xcalloc(1, sizeof(*id)); 1349 id->key = key; 1350 id->filename = xstrdup(options.identity_files[i]); 1351 TAILQ_INSERT_TAIL(&files, id, next); 1352 } 1353 /* list of keys supported by the agent */ 1354 if ((ac = ssh_get_authentication_connection())) { 1355 for (key = ssh_get_first_identity(ac, &comment, 2); 1356 key != NULL; 1357 key = ssh_get_next_identity(ac, &comment, 2)) { 1358 found = 0; 1359 TAILQ_FOREACH(id, &files, next) { 1360 /* agent keys from the config file are preferred */ 1361 if (key_equal(key, id->key)) { 1362 key_free(key); 1363 xfree(comment); 1364 TAILQ_REMOVE(&files, id, next); 1365 TAILQ_INSERT_TAIL(preferred, id, next); 1366 id->ac = ac; 1367 found = 1; 1368 break; 1369 } 1370 } 1371 if (!found && !options.identities_only) { 1372 id = xcalloc(1, sizeof(*id)); 1373 id->key = key; 1374 id->filename = comment; 1375 id->ac = ac; 1376 TAILQ_INSERT_TAIL(&agent, id, next); 1377 } 1378 } 1379 /* append remaining agent keys */ 1380 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1381 TAILQ_REMOVE(&agent, id, next); 1382 TAILQ_INSERT_TAIL(preferred, id, next); 1383 } 1384 authctxt->agent = ac; 1385 } 1386 /* append remaining keys from the config file */ 1387 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1388 TAILQ_REMOVE(&files, id, next); 1389 TAILQ_INSERT_TAIL(preferred, id, next); 1390 } 1391 TAILQ_FOREACH(id, preferred, next) { 1392 debug2("key: %s (%p)", id->filename, id->key); 1393 } 1394 } 1395 1396 static void 1397 pubkey_cleanup(Authctxt *authctxt) 1398 { 1399 Identity *id; 1400 1401 if (authctxt->agent != NULL) 1402 ssh_close_authentication_connection(authctxt->agent); 1403 for (id = TAILQ_FIRST(&authctxt->keys); id; 1404 id = TAILQ_FIRST(&authctxt->keys)) { 1405 TAILQ_REMOVE(&authctxt->keys, id, next); 1406 if (id->key) 1407 key_free(id->key); 1408 if (id->filename) 1409 xfree(id->filename); 1410 xfree(id); 1411 } 1412 } 1413 1414 int 1415 userauth_pubkey(Authctxt *authctxt) 1416 { 1417 Identity *id; 1418 int sent = 0; 1419 1420 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1421 if (id->tried++) 1422 return (0); 1423 /* move key to the end of the queue */ 1424 TAILQ_REMOVE(&authctxt->keys, id, next); 1425 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1426 /* 1427 * send a test message if we have the public key. for 1428 * encrypted keys we cannot do this and have to load the 1429 * private key instead 1430 */ 1431 if (id->key && id->key->type != KEY_RSA1) { 1432 debug("Offering %s public key: %s", key_type(id->key), 1433 id->filename); 1434 sent = send_pubkey_test(authctxt, id); 1435 } else if (id->key == NULL) { 1436 debug("Trying private key: %s", id->filename); 1437 id->key = load_identity_file(id->filename); 1438 if (id->key != NULL) { 1439 id->isprivate = 1; 1440 sent = sign_and_send_pubkey(authctxt, id); 1441 key_free(id->key); 1442 id->key = NULL; 1443 } 1444 } 1445 if (sent) 1446 return (sent); 1447 } 1448 return (0); 1449 } 1450 1451 /* 1452 * Send userauth request message specifying keyboard-interactive method. 1453 */ 1454 int 1455 userauth_kbdint(Authctxt *authctxt) 1456 { 1457 static int attempt = 0; 1458 1459 if (attempt++ >= options.number_of_password_prompts) 1460 return 0; 1461 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1462 if (attempt > 1 && !authctxt->info_req_seen) { 1463 debug3("userauth_kbdint: disable: no info_req_seen"); 1464 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1465 return 0; 1466 } 1467 1468 debug2("userauth_kbdint"); 1469 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1470 packet_put_cstring(authctxt->server_user); 1471 packet_put_cstring(authctxt->service); 1472 packet_put_cstring(authctxt->method->name); 1473 packet_put_cstring(""); /* lang */ 1474 packet_put_cstring(options.kbd_interactive_devices ? 1475 options.kbd_interactive_devices : ""); 1476 packet_send(); 1477 1478 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1479 return 1; 1480 } 1481 1482 /* 1483 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1484 */ 1485 void 1486 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1487 { 1488 Authctxt *authctxt = ctxt; 1489 char *name, *inst, *lang, *prompt, *response; 1490 u_int num_prompts, i; 1491 int echo = 0; 1492 1493 debug2("input_userauth_info_req"); 1494 1495 if (authctxt == NULL) 1496 fatal("input_userauth_info_req: no authentication context"); 1497 1498 authctxt->info_req_seen = 1; 1499 1500 name = packet_get_string(NULL); 1501 inst = packet_get_string(NULL); 1502 lang = packet_get_string(NULL); 1503 if (strlen(name) > 0) 1504 logit("%s", name); 1505 if (strlen(inst) > 0) 1506 logit("%s", inst); 1507 xfree(name); 1508 xfree(inst); 1509 xfree(lang); 1510 1511 num_prompts = packet_get_int(); 1512 /* 1513 * Begin to build info response packet based on prompts requested. 1514 * We commit to providing the correct number of responses, so if 1515 * further on we run into a problem that prevents this, we have to 1516 * be sure and clean this up and send a correct error response. 1517 */ 1518 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1519 packet_put_int(num_prompts); 1520 1521 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1522 for (i = 0; i < num_prompts; i++) { 1523 prompt = packet_get_string(NULL); 1524 echo = packet_get_char(); 1525 1526 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1527 1528 packet_put_cstring(response); 1529 memset(response, 0, strlen(response)); 1530 xfree(response); 1531 xfree(prompt); 1532 } 1533 packet_check_eom(); /* done with parsing incoming message. */ 1534 1535 packet_add_padding(64); 1536 packet_send(); 1537 } 1538 1539 static int 1540 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1541 u_char *data, u_int datalen) 1542 { 1543 Buffer b; 1544 struct stat st; 1545 pid_t pid; 1546 int to[2], from[2], status, version = 2; 1547 1548 debug2("ssh_keysign called"); 1549 1550 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1551 error("ssh_keysign: not installed: %s", strerror(errno)); 1552 return -1; 1553 } 1554 if (fflush(stdout) != 0) 1555 error("ssh_keysign: fflush: %s", strerror(errno)); 1556 if (pipe(to) < 0) { 1557 error("ssh_keysign: pipe: %s", strerror(errno)); 1558 return -1; 1559 } 1560 if (pipe(from) < 0) { 1561 error("ssh_keysign: pipe: %s", strerror(errno)); 1562 return -1; 1563 } 1564 if ((pid = fork()) < 0) { 1565 error("ssh_keysign: fork: %s", strerror(errno)); 1566 return -1; 1567 } 1568 if (pid == 0) { 1569 /* keep the socket on exec */ 1570 fcntl(packet_get_connection_in(), F_SETFD, 0); 1571 permanently_drop_suid(getuid()); 1572 close(from[0]); 1573 if (dup2(from[1], STDOUT_FILENO) < 0) 1574 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1575 close(to[1]); 1576 if (dup2(to[0], STDIN_FILENO) < 0) 1577 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1578 close(from[1]); 1579 close(to[0]); 1580 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1581 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1582 strerror(errno)); 1583 } 1584 close(from[1]); 1585 close(to[0]); 1586 1587 buffer_init(&b); 1588 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1589 buffer_put_string(&b, data, datalen); 1590 if (ssh_msg_send(to[1], version, &b) == -1) 1591 fatal("ssh_keysign: couldn't send request"); 1592 1593 if (ssh_msg_recv(from[0], &b) < 0) { 1594 error("ssh_keysign: no reply"); 1595 buffer_free(&b); 1596 return -1; 1597 } 1598 close(from[0]); 1599 close(to[1]); 1600 1601 while (waitpid(pid, &status, 0) < 0) 1602 if (errno != EINTR) 1603 break; 1604 1605 if (buffer_get_char(&b) != version) { 1606 error("ssh_keysign: bad version"); 1607 buffer_free(&b); 1608 return -1; 1609 } 1610 *sigp = buffer_get_string(&b, lenp); 1611 buffer_free(&b); 1612 1613 return 0; 1614 } 1615 1616 int 1617 userauth_hostbased(Authctxt *authctxt) 1618 { 1619 Key *private = NULL; 1620 Sensitive *sensitive = authctxt->sensitive; 1621 Buffer b; 1622 u_char *signature, *blob; 1623 char *chost, *pkalg, *p; 1624 const char *service; 1625 u_int blen, slen; 1626 int ok, i, found = 0; 1627 1628 /* check for a useful key */ 1629 for (i = 0; i < sensitive->nkeys; i++) { 1630 private = sensitive->keys[i]; 1631 if (private && private->type != KEY_RSA1) { 1632 found = 1; 1633 /* we take and free the key */ 1634 sensitive->keys[i] = NULL; 1635 break; 1636 } 1637 } 1638 if (!found) { 1639 debug("No more client hostkeys for hostbased authentication."); 1640 return 0; 1641 } 1642 if (key_to_blob(private, &blob, &blen) == 0) { 1643 key_free(private); 1644 return 0; 1645 } 1646 /* figure out a name for the client host */ 1647 p = get_local_name(packet_get_connection_in()); 1648 if (p == NULL) { 1649 error("userauth_hostbased: cannot get local ipaddr/name"); 1650 key_free(private); 1651 xfree(blob); 1652 return 0; 1653 } 1654 xasprintf(&chost, "%s.", p); 1655 debug2("userauth_hostbased: chost %s", chost); 1656 xfree(p); 1657 1658 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1659 authctxt->service; 1660 pkalg = xstrdup(key_ssh_name(private)); 1661 buffer_init(&b); 1662 /* construct data */ 1663 buffer_put_string(&b, session_id2, session_id2_len); 1664 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1665 buffer_put_cstring(&b, authctxt->server_user); 1666 buffer_put_cstring(&b, service); 1667 buffer_put_cstring(&b, authctxt->method->name); 1668 buffer_put_cstring(&b, pkalg); 1669 buffer_put_string(&b, blob, blen); 1670 buffer_put_cstring(&b, chost); 1671 buffer_put_cstring(&b, authctxt->local_user); 1672 #ifdef DEBUG_PK 1673 buffer_dump(&b); 1674 #endif 1675 if (sensitive->external_keysign) 1676 ok = ssh_keysign(private, &signature, &slen, 1677 buffer_ptr(&b), buffer_len(&b)); 1678 else 1679 ok = key_sign(private, &signature, &slen, 1680 buffer_ptr(&b), buffer_len(&b)); 1681 key_free(private); 1682 buffer_free(&b); 1683 if (ok != 0) { 1684 error("key_sign failed"); 1685 xfree(chost); 1686 xfree(pkalg); 1687 xfree(blob); 1688 return 0; 1689 } 1690 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1691 packet_put_cstring(authctxt->server_user); 1692 packet_put_cstring(authctxt->service); 1693 packet_put_cstring(authctxt->method->name); 1694 packet_put_cstring(pkalg); 1695 packet_put_string(blob, blen); 1696 packet_put_cstring(chost); 1697 packet_put_cstring(authctxt->local_user); 1698 packet_put_string(signature, slen); 1699 memset(signature, 's', slen); 1700 xfree(signature); 1701 xfree(chost); 1702 xfree(pkalg); 1703 xfree(blob); 1704 1705 packet_send(); 1706 return 1; 1707 } 1708 1709 #ifdef JPAKE 1710 int 1711 userauth_jpake(Authctxt *authctxt) 1712 { 1713 struct jpake_ctx *pctx; 1714 u_char *x1_proof, *x2_proof; 1715 u_int x1_proof_len, x2_proof_len; 1716 static int attempt = 0; /* XXX share with userauth_password's? */ 1717 1718 if (attempt++ >= options.number_of_password_prompts) 1719 return 0; 1720 if (attempt != 1) 1721 error("Permission denied, please try again."); 1722 1723 if (authctxt->methoddata != NULL) 1724 fatal("%s: authctxt->methoddata already set (%p)", 1725 __func__, authctxt->methoddata); 1726 1727 authctxt->methoddata = pctx = jpake_new(); 1728 1729 /* 1730 * Send request immediately, to get the protocol going while 1731 * we do the initial computations. 1732 */ 1733 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1734 packet_put_cstring(authctxt->server_user); 1735 packet_put_cstring(authctxt->service); 1736 packet_put_cstring(authctxt->method->name); 1737 packet_send(); 1738 packet_write_wait(); 1739 1740 jpake_step1(pctx->grp, 1741 &pctx->client_id, &pctx->client_id_len, 1742 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1743 &x1_proof, &x1_proof_len, 1744 &x2_proof, &x2_proof_len); 1745 1746 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1747 1748 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1749 packet_put_string(pctx->client_id, pctx->client_id_len); 1750 packet_put_bignum2(pctx->g_x1); 1751 packet_put_bignum2(pctx->g_x2); 1752 packet_put_string(x1_proof, x1_proof_len); 1753 packet_put_string(x2_proof, x2_proof_len); 1754 packet_send(); 1755 1756 bzero(x1_proof, x1_proof_len); 1757 bzero(x2_proof, x2_proof_len); 1758 xfree(x1_proof); 1759 xfree(x2_proof); 1760 1761 /* Expect step 1 packet from peer */ 1762 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1763 input_userauth_jpake_server_step1); 1764 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1765 &input_userauth_success_unexpected); 1766 1767 return 1; 1768 } 1769 1770 void 1771 userauth_jpake_cleanup(Authctxt *authctxt) 1772 { 1773 debug3("%s: clean up", __func__); 1774 if (authctxt->methoddata != NULL) { 1775 jpake_free(authctxt->methoddata); 1776 authctxt->methoddata = NULL; 1777 } 1778 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1779 } 1780 #endif /* JPAKE */ 1781 1782 /* find auth method */ 1783 1784 /* 1785 * given auth method name, if configurable options permit this method fill 1786 * in auth_ident field and return true, otherwise return false. 1787 */ 1788 static int 1789 authmethod_is_enabled(Authmethod *method) 1790 { 1791 if (method == NULL) 1792 return 0; 1793 /* return false if options indicate this method is disabled */ 1794 if (method->enabled == NULL || *method->enabled == 0) 1795 return 0; 1796 /* return false if batch mode is enabled but method needs interactive mode */ 1797 if (method->batch_flag != NULL && *method->batch_flag != 0) 1798 return 0; 1799 return 1; 1800 } 1801 1802 static Authmethod * 1803 authmethod_lookup(const char *name) 1804 { 1805 Authmethod *method = NULL; 1806 if (name != NULL) 1807 for (method = authmethods; method->name != NULL; method++) 1808 if (strcmp(name, method->name) == 0) 1809 return method; 1810 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1811 return NULL; 1812 } 1813 1814 /* XXX internal state */ 1815 static Authmethod *current = NULL; 1816 static char *supported = NULL; 1817 static char *preferred = NULL; 1818 1819 /* 1820 * Given the authentication method list sent by the server, return the 1821 * next method we should try. If the server initially sends a nil list, 1822 * use a built-in default list. 1823 */ 1824 static Authmethod * 1825 authmethod_get(char *authlist) 1826 { 1827 char *name = NULL; 1828 u_int next; 1829 1830 /* Use a suitable default if we're passed a nil list. */ 1831 if (authlist == NULL || strlen(authlist) == 0) 1832 authlist = options.preferred_authentications; 1833 1834 if (supported == NULL || strcmp(authlist, supported) != 0) { 1835 debug3("start over, passed a different list %s", authlist); 1836 if (supported != NULL) 1837 xfree(supported); 1838 supported = xstrdup(authlist); 1839 preferred = options.preferred_authentications; 1840 debug3("preferred %s", preferred); 1841 current = NULL; 1842 } else if (current != NULL && authmethod_is_enabled(current)) 1843 return current; 1844 1845 for (;;) { 1846 if ((name = match_list(preferred, supported, &next)) == NULL) { 1847 debug("No more authentication methods to try."); 1848 current = NULL; 1849 return NULL; 1850 } 1851 preferred += next; 1852 debug3("authmethod_lookup %s", name); 1853 debug3("remaining preferred: %s", preferred); 1854 if ((current = authmethod_lookup(name)) != NULL && 1855 authmethod_is_enabled(current)) { 1856 debug3("authmethod_is_enabled %s", name); 1857 debug("Next authentication method: %s", name); 1858 return current; 1859 } 1860 } 1861 } 1862 1863 static char * 1864 authmethods_get(void) 1865 { 1866 Authmethod *method = NULL; 1867 Buffer b; 1868 char *list; 1869 1870 buffer_init(&b); 1871 for (method = authmethods; method->name != NULL; method++) { 1872 if (authmethod_is_enabled(method)) { 1873 if (buffer_len(&b) > 0) 1874 buffer_append(&b, ",", 1); 1875 buffer_append(&b, method->name, strlen(method->name)); 1876 } 1877 } 1878 buffer_append(&b, "\0", 1); 1879 list = xstrdup(buffer_ptr(&b)); 1880 buffer_free(&b); 1881 return list; 1882 } 1883 1884