1 /* 2 * Copyright (c) 2000 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #include "includes.h" 26 RCSID("$OpenBSD: sshconnect2.c,v 1.120 2003/06/24 08:23:46 markus Exp $"); 27 28 #ifdef KRB5 29 #include <krb5.h> 30 #endif 31 32 #include "ssh.h" 33 #include "ssh2.h" 34 #include "xmalloc.h" 35 #include "buffer.h" 36 #include "packet.h" 37 #include "compat.h" 38 #include "bufaux.h" 39 #include "cipher.h" 40 #include "kex.h" 41 #include "myproposal.h" 42 #include "sshconnect.h" 43 #include "authfile.h" 44 #include "dh.h" 45 #include "authfd.h" 46 #include "log.h" 47 #include "readconf.h" 48 #include "readpass.h" 49 #include "match.h" 50 #include "dispatch.h" 51 #include "canohost.h" 52 #include "msg.h" 53 #include "pathnames.h" 54 55 /* import */ 56 extern char *client_version_string; 57 extern char *server_version_string; 58 extern Options options; 59 60 /* 61 * SSH2 key exchange 62 */ 63 64 u_char *session_id2 = NULL; 65 u_int session_id2_len = 0; 66 67 char *xxx_host; 68 struct sockaddr *xxx_hostaddr; 69 70 Kex *xxx_kex = NULL; 71 72 static int 73 verify_host_key_callback(Key *hostkey) 74 { 75 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 76 fatal("Host key verification failed."); 77 return 0; 78 } 79 80 void 81 ssh_kex2(char *host, struct sockaddr *hostaddr) 82 { 83 Kex *kex; 84 85 xxx_host = host; 86 xxx_hostaddr = hostaddr; 87 88 if (options.ciphers == (char *)-1) { 89 logit("No valid ciphers for protocol version 2 given, using defaults."); 90 options.ciphers = NULL; 91 } 92 if (options.ciphers != NULL) { 93 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 94 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 95 } 96 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 97 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 98 myproposal[PROPOSAL_ENC_ALGS_STOC] = 99 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 100 if (options.compression) { 101 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 102 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none"; 103 } else { 104 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 105 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib"; 106 } 107 if (options.macs != NULL) { 108 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 109 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 110 } 111 if (options.hostkeyalgorithms != NULL) 112 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 113 options.hostkeyalgorithms; 114 115 if (options.rekey_limit) 116 packet_set_rekey_limit(options.rekey_limit); 117 118 /* start key exchange */ 119 kex = kex_setup(myproposal); 120 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 121 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 122 kex->client_version_string=client_version_string; 123 kex->server_version_string=server_version_string; 124 kex->verify_host_key=&verify_host_key_callback; 125 126 xxx_kex = kex; 127 128 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 129 130 session_id2 = kex->session_id; 131 session_id2_len = kex->session_id_len; 132 133 #ifdef DEBUG_KEXDH 134 /* send 1st encrypted/maced/compressed message */ 135 packet_start(SSH2_MSG_IGNORE); 136 packet_put_cstring("markus"); 137 packet_send(); 138 packet_write_wait(); 139 #endif 140 } 141 142 /* 143 * Authenticate user 144 */ 145 146 typedef struct Authctxt Authctxt; 147 typedef struct Authmethod Authmethod; 148 typedef struct identity Identity; 149 typedef struct idlist Idlist; 150 151 struct identity { 152 TAILQ_ENTRY(identity) next; 153 AuthenticationConnection *ac; /* set if agent supports key */ 154 Key *key; /* public/private key */ 155 char *filename; /* comment for agent-only keys */ 156 int tried; 157 int isprivate; /* key points to the private key */ 158 }; 159 TAILQ_HEAD(idlist, identity); 160 161 struct Authctxt { 162 const char *server_user; 163 const char *local_user; 164 const char *host; 165 const char *service; 166 Authmethod *method; 167 int success; 168 char *authlist; 169 /* pubkey */ 170 Idlist keys; 171 AuthenticationConnection *agent; 172 /* hostbased */ 173 Sensitive *sensitive; 174 /* kbd-interactive */ 175 int info_req_seen; 176 }; 177 struct Authmethod { 178 char *name; /* string to compare against server's list */ 179 int (*userauth)(Authctxt *authctxt); 180 int *enabled; /* flag in option struct that enables method */ 181 int *batch_flag; /* flag in option struct that disables method */ 182 }; 183 184 void input_userauth_success(int, u_int32_t, void *); 185 void input_userauth_failure(int, u_int32_t, void *); 186 void input_userauth_banner(int, u_int32_t, void *); 187 void input_userauth_error(int, u_int32_t, void *); 188 void input_userauth_info_req(int, u_int32_t, void *); 189 void input_userauth_pk_ok(int, u_int32_t, void *); 190 void input_userauth_passwd_changereq(int, u_int32_t, void *); 191 192 int userauth_none(Authctxt *); 193 int userauth_pubkey(Authctxt *); 194 int userauth_passwd(Authctxt *); 195 int userauth_kbdint(Authctxt *); 196 int userauth_hostbased(Authctxt *); 197 int userauth_kerberos(Authctxt *); 198 199 void userauth(Authctxt *, char *); 200 201 static int sign_and_send_pubkey(Authctxt *, Identity *); 202 static void pubkey_prepare(Authctxt *); 203 static void pubkey_cleanup(Authctxt *); 204 static Key *load_identity_file(char *); 205 206 static Authmethod *authmethod_get(char *authlist); 207 static Authmethod *authmethod_lookup(const char *name); 208 static char *authmethods_get(void); 209 210 Authmethod authmethods[] = { 211 {"hostbased", 212 userauth_hostbased, 213 &options.hostbased_authentication, 214 NULL}, 215 #if KRB5 216 {"kerberos-2@ssh.com", 217 userauth_kerberos, 218 &options.kerberos_authentication, 219 NULL}, 220 #endif 221 {"publickey", 222 userauth_pubkey, 223 &options.pubkey_authentication, 224 NULL}, 225 {"keyboard-interactive", 226 userauth_kbdint, 227 &options.kbd_interactive_authentication, 228 &options.batch_mode}, 229 {"password", 230 userauth_passwd, 231 &options.password_authentication, 232 &options.batch_mode}, 233 {"none", 234 userauth_none, 235 NULL, 236 NULL}, 237 {NULL, NULL, NULL, NULL} 238 }; 239 240 void 241 ssh_userauth2(const char *local_user, const char *server_user, char *host, 242 Sensitive *sensitive) 243 { 244 Authctxt authctxt; 245 int type; 246 247 if (options.challenge_response_authentication) 248 options.kbd_interactive_authentication = 1; 249 250 packet_start(SSH2_MSG_SERVICE_REQUEST); 251 packet_put_cstring("ssh-userauth"); 252 packet_send(); 253 debug("SSH2_MSG_SERVICE_REQUEST sent"); 254 packet_write_wait(); 255 type = packet_read(); 256 if (type != SSH2_MSG_SERVICE_ACCEPT) 257 fatal("Server denied authentication request: %d", type); 258 if (packet_remaining() > 0) { 259 char *reply = packet_get_string(NULL); 260 debug2("service_accept: %s", reply); 261 xfree(reply); 262 } else { 263 debug2("buggy server: service_accept w/o service"); 264 } 265 packet_check_eom(); 266 debug("SSH2_MSG_SERVICE_ACCEPT received"); 267 268 if (options.preferred_authentications == NULL) 269 options.preferred_authentications = authmethods_get(); 270 271 /* setup authentication context */ 272 memset(&authctxt, 0, sizeof(authctxt)); 273 pubkey_prepare(&authctxt); 274 authctxt.server_user = server_user; 275 authctxt.local_user = local_user; 276 authctxt.host = host; 277 authctxt.service = "ssh-connection"; /* service name */ 278 authctxt.success = 0; 279 authctxt.method = authmethod_lookup("none"); 280 authctxt.authlist = NULL; 281 authctxt.sensitive = sensitive; 282 authctxt.info_req_seen = 0; 283 if (authctxt.method == NULL) 284 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 285 286 /* initial userauth request */ 287 userauth_none(&authctxt); 288 289 dispatch_init(&input_userauth_error); 290 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 291 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 292 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 293 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 294 295 pubkey_cleanup(&authctxt); 296 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 297 298 debug("Authentication succeeded (%s).", authctxt.method->name); 299 } 300 301 void 302 userauth(Authctxt *authctxt, char *authlist) 303 { 304 if (authlist == NULL) { 305 authlist = authctxt->authlist; 306 } else { 307 if (authctxt->authlist) 308 xfree(authctxt->authlist); 309 authctxt->authlist = authlist; 310 } 311 for (;;) { 312 Authmethod *method = authmethod_get(authlist); 313 if (method == NULL) 314 fatal("Permission denied (%s).", authlist); 315 authctxt->method = method; 316 317 /* reset the per method handler */ 318 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 319 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 320 321 /* and try new method */ 322 if (method->userauth(authctxt) != 0) { 323 debug2("we sent a %s packet, wait for reply", method->name); 324 break; 325 } else { 326 debug2("we did not send a packet, disable method"); 327 method->enabled = NULL; 328 } 329 } 330 } 331 332 void 333 input_userauth_error(int type, u_int32_t seq, void *ctxt) 334 { 335 fatal("input_userauth_error: bad message during authentication: " 336 "type %d", type); 337 } 338 339 void 340 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 341 { 342 char *msg, *lang; 343 debug3("input_userauth_banner"); 344 msg = packet_get_string(NULL); 345 lang = packet_get_string(NULL); 346 fprintf(stderr, "%s", msg); 347 xfree(msg); 348 xfree(lang); 349 } 350 351 void 352 input_userauth_success(int type, u_int32_t seq, void *ctxt) 353 { 354 Authctxt *authctxt = ctxt; 355 if (authctxt == NULL) 356 fatal("input_userauth_success: no authentication context"); 357 if (authctxt->authlist) 358 xfree(authctxt->authlist); 359 authctxt->success = 1; /* break out */ 360 } 361 362 void 363 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 364 { 365 Authctxt *authctxt = ctxt; 366 char *authlist = NULL; 367 int partial; 368 369 if (authctxt == NULL) 370 fatal("input_userauth_failure: no authentication context"); 371 372 authlist = packet_get_string(NULL); 373 partial = packet_get_char(); 374 packet_check_eom(); 375 376 if (partial != 0) 377 logit("Authenticated with partial success."); 378 debug("Authentications that can continue: %s", authlist); 379 380 userauth(authctxt, authlist); 381 } 382 void 383 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 384 { 385 Authctxt *authctxt = ctxt; 386 Key *key = NULL; 387 Identity *id = NULL; 388 Buffer b; 389 int pktype, sent = 0; 390 u_int alen, blen; 391 char *pkalg, *fp; 392 u_char *pkblob; 393 394 if (authctxt == NULL) 395 fatal("input_userauth_pk_ok: no authentication context"); 396 if (datafellows & SSH_BUG_PKOK) { 397 /* this is similar to SSH_BUG_PKAUTH */ 398 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 399 pkblob = packet_get_string(&blen); 400 buffer_init(&b); 401 buffer_append(&b, pkblob, blen); 402 pkalg = buffer_get_string(&b, &alen); 403 buffer_free(&b); 404 } else { 405 pkalg = packet_get_string(&alen); 406 pkblob = packet_get_string(&blen); 407 } 408 packet_check_eom(); 409 410 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 411 412 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 413 debug("unknown pkalg %s", pkalg); 414 goto done; 415 } 416 if ((key = key_from_blob(pkblob, blen)) == NULL) { 417 debug("no key from blob. pkalg %s", pkalg); 418 goto done; 419 } 420 if (key->type != pktype) { 421 error("input_userauth_pk_ok: type mismatch " 422 "for decoded key (received %d, expected %d)", 423 key->type, pktype); 424 goto done; 425 } 426 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 427 debug2("input_userauth_pk_ok: fp %s", fp); 428 xfree(fp); 429 430 TAILQ_FOREACH(id, &authctxt->keys, next) { 431 if (key_equal(key, id->key)) { 432 sent = sign_and_send_pubkey(authctxt, id); 433 break; 434 } 435 } 436 done: 437 if (key != NULL) 438 key_free(key); 439 xfree(pkalg); 440 xfree(pkblob); 441 442 /* try another method if we did not send a packet */ 443 if (sent == 0) 444 userauth(authctxt, NULL); 445 } 446 447 int 448 userauth_none(Authctxt *authctxt) 449 { 450 /* initial userauth request */ 451 packet_start(SSH2_MSG_USERAUTH_REQUEST); 452 packet_put_cstring(authctxt->server_user); 453 packet_put_cstring(authctxt->service); 454 packet_put_cstring(authctxt->method->name); 455 packet_send(); 456 return 1; 457 } 458 459 int 460 userauth_passwd(Authctxt *authctxt) 461 { 462 static int attempt = 0; 463 char prompt[150]; 464 char *password; 465 466 if (attempt++ >= options.number_of_password_prompts) 467 return 0; 468 469 if (attempt != 1) 470 error("Permission denied, please try again."); 471 472 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 473 authctxt->server_user, authctxt->host); 474 password = read_passphrase(prompt, 0); 475 packet_start(SSH2_MSG_USERAUTH_REQUEST); 476 packet_put_cstring(authctxt->server_user); 477 packet_put_cstring(authctxt->service); 478 packet_put_cstring(authctxt->method->name); 479 packet_put_char(0); 480 packet_put_cstring(password); 481 memset(password, 0, strlen(password)); 482 xfree(password); 483 packet_add_padding(64); 484 packet_send(); 485 486 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 487 &input_userauth_passwd_changereq); 488 489 return 1; 490 } 491 /* 492 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 493 */ 494 void 495 input_userauth_passwd_changereq(int type, uint32_t seqnr, void *ctxt) 496 { 497 Authctxt *authctxt = ctxt; 498 char *info, *lang, *password = NULL, *retype = NULL; 499 char prompt[150]; 500 501 debug2("input_userauth_passwd_changereq"); 502 503 if (authctxt == NULL) 504 fatal("input_userauth_passwd_changereq: " 505 "no authentication context"); 506 507 info = packet_get_string(NULL); 508 lang = packet_get_string(NULL); 509 if (strlen(info) > 0) 510 logit("%s", info); 511 xfree(info); 512 xfree(lang); 513 packet_start(SSH2_MSG_USERAUTH_REQUEST); 514 packet_put_cstring(authctxt->server_user); 515 packet_put_cstring(authctxt->service); 516 packet_put_cstring(authctxt->method->name); 517 packet_put_char(1); /* additional info */ 518 snprintf(prompt, sizeof(prompt), 519 "Enter %.30s@%.128s's old password: ", 520 authctxt->server_user, authctxt->host); 521 password = read_passphrase(prompt, 0); 522 packet_put_cstring(password); 523 memset(password, 0, strlen(password)); 524 xfree(password); 525 password = NULL; 526 while (password == NULL) { 527 snprintf(prompt, sizeof(prompt), 528 "Enter %.30s@%.128s's new password: ", 529 authctxt->server_user, authctxt->host); 530 password = read_passphrase(prompt, RP_ALLOW_EOF); 531 if (password == NULL) { 532 /* bail out */ 533 return; 534 } 535 snprintf(prompt, sizeof(prompt), 536 "Retype %.30s@%.128s's new password: ", 537 authctxt->server_user, authctxt->host); 538 retype = read_passphrase(prompt, 0); 539 if (strcmp(password, retype) != 0) { 540 memset(password, 0, strlen(password)); 541 xfree(password); 542 logit("Mismatch; try again, EOF to quit."); 543 password = NULL; 544 } 545 memset(retype, 0, strlen(retype)); 546 xfree(retype); 547 } 548 packet_put_cstring(password); 549 memset(password, 0, strlen(password)); 550 xfree(password); 551 packet_add_padding(64); 552 packet_send(); 553 554 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 555 &input_userauth_passwd_changereq); 556 } 557 558 static int 559 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 560 u_char *data, u_int datalen) 561 { 562 Key *prv; 563 int ret; 564 565 /* the agent supports this key */ 566 if (id->ac) 567 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 568 data, datalen)); 569 /* 570 * we have already loaded the private key or 571 * the private key is stored in external hardware 572 */ 573 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 574 return (key_sign(id->key, sigp, lenp, data, datalen)); 575 /* load the private key from the file */ 576 if ((prv = load_identity_file(id->filename)) == NULL) 577 return (-1); 578 ret = key_sign(prv, sigp, lenp, data, datalen); 579 key_free(prv); 580 return (ret); 581 } 582 583 static int 584 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 585 { 586 Buffer b; 587 u_char *blob, *signature; 588 u_int bloblen, slen; 589 u_int skip = 0; 590 int ret = -1; 591 int have_sig = 1; 592 593 debug3("sign_and_send_pubkey"); 594 595 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 596 /* we cannot handle this key */ 597 debug3("sign_and_send_pubkey: cannot handle key"); 598 return 0; 599 } 600 /* data to be signed */ 601 buffer_init(&b); 602 if (datafellows & SSH_OLD_SESSIONID) { 603 buffer_append(&b, session_id2, session_id2_len); 604 skip = session_id2_len; 605 } else { 606 buffer_put_string(&b, session_id2, session_id2_len); 607 skip = buffer_len(&b); 608 } 609 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 610 buffer_put_cstring(&b, authctxt->server_user); 611 buffer_put_cstring(&b, 612 datafellows & SSH_BUG_PKSERVICE ? 613 "ssh-userauth" : 614 authctxt->service); 615 if (datafellows & SSH_BUG_PKAUTH) { 616 buffer_put_char(&b, have_sig); 617 } else { 618 buffer_put_cstring(&b, authctxt->method->name); 619 buffer_put_char(&b, have_sig); 620 buffer_put_cstring(&b, key_ssh_name(id->key)); 621 } 622 buffer_put_string(&b, blob, bloblen); 623 624 /* generate signature */ 625 ret = identity_sign(id, &signature, &slen, 626 buffer_ptr(&b), buffer_len(&b)); 627 if (ret == -1) { 628 xfree(blob); 629 buffer_free(&b); 630 return 0; 631 } 632 #ifdef DEBUG_PK 633 buffer_dump(&b); 634 #endif 635 if (datafellows & SSH_BUG_PKSERVICE) { 636 buffer_clear(&b); 637 buffer_append(&b, session_id2, session_id2_len); 638 skip = session_id2_len; 639 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 640 buffer_put_cstring(&b, authctxt->server_user); 641 buffer_put_cstring(&b, authctxt->service); 642 buffer_put_cstring(&b, authctxt->method->name); 643 buffer_put_char(&b, have_sig); 644 if (!(datafellows & SSH_BUG_PKAUTH)) 645 buffer_put_cstring(&b, key_ssh_name(id->key)); 646 buffer_put_string(&b, blob, bloblen); 647 } 648 xfree(blob); 649 650 /* append signature */ 651 buffer_put_string(&b, signature, slen); 652 xfree(signature); 653 654 /* skip session id and packet type */ 655 if (buffer_len(&b) < skip + 1) 656 fatal("userauth_pubkey: internal error"); 657 buffer_consume(&b, skip + 1); 658 659 /* put remaining data from buffer into packet */ 660 packet_start(SSH2_MSG_USERAUTH_REQUEST); 661 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 662 buffer_free(&b); 663 packet_send(); 664 665 return 1; 666 } 667 668 static int 669 send_pubkey_test(Authctxt *authctxt, Identity *id) 670 { 671 u_char *blob; 672 u_int bloblen, have_sig = 0; 673 674 debug3("send_pubkey_test"); 675 676 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 677 /* we cannot handle this key */ 678 debug3("send_pubkey_test: cannot handle key"); 679 return 0; 680 } 681 /* register callback for USERAUTH_PK_OK message */ 682 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 683 684 packet_start(SSH2_MSG_USERAUTH_REQUEST); 685 packet_put_cstring(authctxt->server_user); 686 packet_put_cstring(authctxt->service); 687 packet_put_cstring(authctxt->method->name); 688 packet_put_char(have_sig); 689 if (!(datafellows & SSH_BUG_PKAUTH)) 690 packet_put_cstring(key_ssh_name(id->key)); 691 packet_put_string(blob, bloblen); 692 xfree(blob); 693 packet_send(); 694 return 1; 695 } 696 697 static Key * 698 load_identity_file(char *filename) 699 { 700 Key *private; 701 char prompt[300], *passphrase; 702 int quit, i; 703 struct stat st; 704 705 if (stat(filename, &st) < 0) { 706 debug3("no such identity: %s", filename); 707 return NULL; 708 } 709 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 710 if (private == NULL) { 711 if (options.batch_mode) 712 return NULL; 713 snprintf(prompt, sizeof prompt, 714 "Enter passphrase for key '%.100s': ", filename); 715 for (i = 0; i < options.number_of_password_prompts; i++) { 716 passphrase = read_passphrase(prompt, 0); 717 if (strcmp(passphrase, "") != 0) { 718 private = key_load_private_type(KEY_UNSPEC, filename, 719 passphrase, NULL); 720 quit = 0; 721 } else { 722 debug2("no passphrase given, try next key"); 723 quit = 1; 724 } 725 memset(passphrase, 0, strlen(passphrase)); 726 xfree(passphrase); 727 if (private != NULL || quit) 728 break; 729 debug2("bad passphrase given, try again..."); 730 } 731 } 732 return private; 733 } 734 735 /* 736 * try keys in the following order: 737 * 1. agent keys that are found in the config file 738 * 2. other agent keys 739 * 3. keys that are only listed in the config file 740 */ 741 static void 742 pubkey_prepare(Authctxt *authctxt) 743 { 744 Identity *id; 745 Idlist agent, files, *preferred; 746 Key *key; 747 AuthenticationConnection *ac; 748 char *comment; 749 int i, found; 750 751 TAILQ_INIT(&agent); /* keys from the agent */ 752 TAILQ_INIT(&files); /* keys from the config file */ 753 preferred = &authctxt->keys; 754 TAILQ_INIT(preferred); /* preferred order of keys */ 755 756 /* list of keys stored in the filesystem */ 757 for (i = 0; i < options.num_identity_files; i++) { 758 key = options.identity_keys[i]; 759 if (key && key->type == KEY_RSA1) 760 continue; 761 options.identity_keys[i] = NULL; 762 id = xmalloc(sizeof(*id)); 763 memset(id, 0, sizeof(*id)); 764 id->key = key; 765 id->filename = xstrdup(options.identity_files[i]); 766 TAILQ_INSERT_TAIL(&files, id, next); 767 } 768 /* list of keys supported by the agent */ 769 if ((ac = ssh_get_authentication_connection())) { 770 for (key = ssh_get_first_identity(ac, &comment, 2); 771 key != NULL; 772 key = ssh_get_next_identity(ac, &comment, 2)) { 773 found = 0; 774 TAILQ_FOREACH(id, &files, next) { 775 /* agent keys from the config file are preferred */ 776 if (key_equal(key, id->key)) { 777 key_free(key); 778 xfree(comment); 779 TAILQ_REMOVE(&files, id, next); 780 TAILQ_INSERT_TAIL(preferred, id, next); 781 id->ac = ac; 782 found = 1; 783 break; 784 } 785 } 786 if (!found) { 787 id = xmalloc(sizeof(*id)); 788 memset(id, 0, sizeof(*id)); 789 id->key = key; 790 id->filename = comment; 791 id->ac = ac; 792 TAILQ_INSERT_TAIL(&agent, id, next); 793 } 794 } 795 /* append remaining agent keys */ 796 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 797 TAILQ_REMOVE(&agent, id, next); 798 TAILQ_INSERT_TAIL(preferred, id, next); 799 } 800 authctxt->agent = ac; 801 } 802 /* append remaining keys from the config file */ 803 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 804 TAILQ_REMOVE(&files, id, next); 805 TAILQ_INSERT_TAIL(preferred, id, next); 806 } 807 TAILQ_FOREACH(id, preferred, next) { 808 debug2("key: %s (%p)", id->filename, id->key); 809 } 810 } 811 812 static void 813 pubkey_cleanup(Authctxt *authctxt) 814 { 815 Identity *id; 816 817 if (authctxt->agent != NULL) 818 ssh_close_authentication_connection(authctxt->agent); 819 for (id = TAILQ_FIRST(&authctxt->keys); id; 820 id = TAILQ_FIRST(&authctxt->keys)) { 821 TAILQ_REMOVE(&authctxt->keys, id, next); 822 if (id->key) 823 key_free(id->key); 824 if (id->filename) 825 xfree(id->filename); 826 xfree(id); 827 } 828 } 829 830 int 831 userauth_pubkey(Authctxt *authctxt) 832 { 833 Identity *id; 834 int sent = 0; 835 836 while ((id = TAILQ_FIRST(&authctxt->keys))) { 837 if (id->tried++) 838 return (0); 839 TAILQ_REMOVE(&authctxt->keys, id, next); 840 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 841 /* 842 * send a test message if we have the public key. for 843 * encrypted keys we cannot do this and have to load the 844 * private key instead 845 */ 846 if (id->key && id->key->type != KEY_RSA1) { 847 debug("Offering public key: %s", id->filename); 848 sent = send_pubkey_test(authctxt, id); 849 } else if (id->key == NULL) { 850 debug("Trying private key: %s", id->filename); 851 id->key = load_identity_file(id->filename); 852 if (id->key != NULL) { 853 id->isprivate = 1; 854 sent = sign_and_send_pubkey(authctxt, id); 855 key_free(id->key); 856 id->key = NULL; 857 } 858 } 859 if (sent) 860 return (sent); 861 } 862 return (0); 863 } 864 865 /* 866 * Send userauth request message specifying keyboard-interactive method. 867 */ 868 int 869 userauth_kbdint(Authctxt *authctxt) 870 { 871 static int attempt = 0; 872 873 if (attempt++ >= options.number_of_password_prompts) 874 return 0; 875 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 876 if (attempt > 1 && !authctxt->info_req_seen) { 877 debug3("userauth_kbdint: disable: no info_req_seen"); 878 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 879 return 0; 880 } 881 882 debug2("userauth_kbdint"); 883 packet_start(SSH2_MSG_USERAUTH_REQUEST); 884 packet_put_cstring(authctxt->server_user); 885 packet_put_cstring(authctxt->service); 886 packet_put_cstring(authctxt->method->name); 887 packet_put_cstring(""); /* lang */ 888 packet_put_cstring(options.kbd_interactive_devices ? 889 options.kbd_interactive_devices : ""); 890 packet_send(); 891 892 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 893 return 1; 894 } 895 896 /* 897 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 898 */ 899 void 900 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 901 { 902 Authctxt *authctxt = ctxt; 903 char *name, *inst, *lang, *prompt, *response; 904 u_int num_prompts, i; 905 int echo = 0; 906 907 debug2("input_userauth_info_req"); 908 909 if (authctxt == NULL) 910 fatal("input_userauth_info_req: no authentication context"); 911 912 authctxt->info_req_seen = 1; 913 914 name = packet_get_string(NULL); 915 inst = packet_get_string(NULL); 916 lang = packet_get_string(NULL); 917 if (strlen(name) > 0) 918 logit("%s", name); 919 if (strlen(inst) > 0) 920 logit("%s", inst); 921 xfree(name); 922 xfree(inst); 923 xfree(lang); 924 925 num_prompts = packet_get_int(); 926 /* 927 * Begin to build info response packet based on prompts requested. 928 * We commit to providing the correct number of responses, so if 929 * further on we run into a problem that prevents this, we have to 930 * be sure and clean this up and send a correct error response. 931 */ 932 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 933 packet_put_int(num_prompts); 934 935 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 936 for (i = 0; i < num_prompts; i++) { 937 prompt = packet_get_string(NULL); 938 echo = packet_get_char(); 939 940 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 941 942 packet_put_cstring(response); 943 memset(response, 0, strlen(response)); 944 xfree(response); 945 xfree(prompt); 946 } 947 packet_check_eom(); /* done with parsing incoming message. */ 948 949 packet_add_padding(64); 950 packet_send(); 951 } 952 953 static int 954 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 955 u_char *data, u_int datalen) 956 { 957 Buffer b; 958 struct stat st; 959 pid_t pid; 960 int to[2], from[2], status, version = 2; 961 962 debug2("ssh_keysign called"); 963 964 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 965 error("ssh_keysign: no installed: %s", strerror(errno)); 966 return -1; 967 } 968 if (fflush(stdout) != 0) 969 error("ssh_keysign: fflush: %s", strerror(errno)); 970 if (pipe(to) < 0) { 971 error("ssh_keysign: pipe: %s", strerror(errno)); 972 return -1; 973 } 974 if (pipe(from) < 0) { 975 error("ssh_keysign: pipe: %s", strerror(errno)); 976 return -1; 977 } 978 if ((pid = fork()) < 0) { 979 error("ssh_keysign: fork: %s", strerror(errno)); 980 return -1; 981 } 982 if (pid == 0) { 983 seteuid(getuid()); 984 setuid(getuid()); 985 close(from[0]); 986 if (dup2(from[1], STDOUT_FILENO) < 0) 987 fatal("ssh_keysign: dup2: %s", strerror(errno)); 988 close(to[1]); 989 if (dup2(to[0], STDIN_FILENO) < 0) 990 fatal("ssh_keysign: dup2: %s", strerror(errno)); 991 close(from[1]); 992 close(to[0]); 993 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 994 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 995 strerror(errno)); 996 } 997 close(from[1]); 998 close(to[0]); 999 1000 buffer_init(&b); 1001 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1002 buffer_put_string(&b, data, datalen); 1003 ssh_msg_send(to[1], version, &b); 1004 1005 if (ssh_msg_recv(from[0], &b) < 0) { 1006 error("ssh_keysign: no reply"); 1007 buffer_clear(&b); 1008 return -1; 1009 } 1010 close(from[0]); 1011 close(to[1]); 1012 1013 while (waitpid(pid, &status, 0) < 0) 1014 if (errno != EINTR) 1015 break; 1016 1017 if (buffer_get_char(&b) != version) { 1018 error("ssh_keysign: bad version"); 1019 buffer_clear(&b); 1020 return -1; 1021 } 1022 *sigp = buffer_get_string(&b, lenp); 1023 buffer_clear(&b); 1024 1025 return 0; 1026 } 1027 1028 int 1029 userauth_hostbased(Authctxt *authctxt) 1030 { 1031 Key *private = NULL; 1032 Sensitive *sensitive = authctxt->sensitive; 1033 Buffer b; 1034 u_char *signature, *blob; 1035 char *chost, *pkalg, *p; 1036 const char *service; 1037 u_int blen, slen; 1038 int ok, i, len, found = 0; 1039 1040 /* check for a useful key */ 1041 for (i = 0; i < sensitive->nkeys; i++) { 1042 private = sensitive->keys[i]; 1043 if (private && private->type != KEY_RSA1) { 1044 found = 1; 1045 /* we take and free the key */ 1046 sensitive->keys[i] = NULL; 1047 break; 1048 } 1049 } 1050 if (!found) { 1051 debug("No more client hostkeys for hostbased authentication."); 1052 return 0; 1053 } 1054 if (key_to_blob(private, &blob, &blen) == 0) { 1055 key_free(private); 1056 return 0; 1057 } 1058 /* figure out a name for the client host */ 1059 p = get_local_name(packet_get_connection_in()); 1060 if (p == NULL) { 1061 error("userauth_hostbased: cannot get local ipaddr/name"); 1062 key_free(private); 1063 return 0; 1064 } 1065 len = strlen(p) + 2; 1066 chost = xmalloc(len); 1067 strlcpy(chost, p, len); 1068 strlcat(chost, ".", len); 1069 debug2("userauth_hostbased: chost %s", chost); 1070 xfree(p); 1071 1072 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1073 authctxt->service; 1074 pkalg = xstrdup(key_ssh_name(private)); 1075 buffer_init(&b); 1076 /* construct data */ 1077 buffer_put_string(&b, session_id2, session_id2_len); 1078 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1079 buffer_put_cstring(&b, authctxt->server_user); 1080 buffer_put_cstring(&b, service); 1081 buffer_put_cstring(&b, authctxt->method->name); 1082 buffer_put_cstring(&b, pkalg); 1083 buffer_put_string(&b, blob, blen); 1084 buffer_put_cstring(&b, chost); 1085 buffer_put_cstring(&b, authctxt->local_user); 1086 #ifdef DEBUG_PK 1087 buffer_dump(&b); 1088 #endif 1089 if (sensitive->external_keysign) 1090 ok = ssh_keysign(private, &signature, &slen, 1091 buffer_ptr(&b), buffer_len(&b)); 1092 else 1093 ok = key_sign(private, &signature, &slen, 1094 buffer_ptr(&b), buffer_len(&b)); 1095 key_free(private); 1096 buffer_free(&b); 1097 if (ok != 0) { 1098 error("key_sign failed"); 1099 xfree(chost); 1100 xfree(pkalg); 1101 return 0; 1102 } 1103 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1104 packet_put_cstring(authctxt->server_user); 1105 packet_put_cstring(authctxt->service); 1106 packet_put_cstring(authctxt->method->name); 1107 packet_put_cstring(pkalg); 1108 packet_put_string(blob, blen); 1109 packet_put_cstring(chost); 1110 packet_put_cstring(authctxt->local_user); 1111 packet_put_string(signature, slen); 1112 memset(signature, 's', slen); 1113 xfree(signature); 1114 xfree(chost); 1115 xfree(pkalg); 1116 1117 packet_send(); 1118 return 1; 1119 } 1120 1121 #if KRB5 1122 static int 1123 ssh_krb5_helper(krb5_data *ap) 1124 { 1125 krb5_context xcontext = NULL; /* XXX share with ssh1 */ 1126 krb5_auth_context xauth_context = NULL; 1127 1128 krb5_context *context; 1129 krb5_auth_context *auth_context; 1130 krb5_error_code problem; 1131 const char *tkfile; 1132 struct stat buf; 1133 krb5_ccache ccache = NULL; 1134 const char *remotehost; 1135 int ret; 1136 1137 memset(ap, 0, sizeof(*ap)); 1138 1139 context = &xcontext; 1140 auth_context = &xauth_context; 1141 1142 problem = krb5_init_context(context); 1143 if (problem) { 1144 debug("Kerberos v5: krb5_init_context failed"); 1145 ret = 0; 1146 goto out; 1147 } 1148 1149 tkfile = krb5_cc_default_name(*context); 1150 if (strncmp(tkfile, "FILE:", 5) == 0) 1151 tkfile += 5; 1152 1153 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 1154 debug("Kerberos v5: could not get default ccache (permission denied)."); 1155 ret = 0; 1156 goto out; 1157 } 1158 1159 problem = krb5_cc_default(*context, &ccache); 1160 if (problem) { 1161 debug("Kerberos v5: krb5_cc_default failed: %s", 1162 krb5_get_err_text(*context, problem)); 1163 ret = 0; 1164 goto out; 1165 } 1166 1167 remotehost = get_canonical_hostname(1); 1168 1169 problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED, 1170 "host", remotehost, NULL, ccache, ap); 1171 if (problem) { 1172 debug("Kerberos v5: krb5_mk_req failed: %s", 1173 krb5_get_err_text(*context, problem)); 1174 ret = 0; 1175 goto out; 1176 } 1177 ret = 1; 1178 1179 out: 1180 if (ccache != NULL) 1181 krb5_cc_close(*context, ccache); 1182 if (*auth_context) 1183 krb5_auth_con_free(*context, *auth_context); 1184 if (*context) 1185 krb5_free_context(*context); 1186 return (ret); 1187 } 1188 1189 int 1190 userauth_kerberos(Authctxt *authctxt) 1191 { 1192 krb5_data ap; 1193 1194 if (ssh_krb5_helper(&ap) == 0) 1195 return (0); 1196 1197 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1198 packet_put_cstring(authctxt->server_user); 1199 packet_put_cstring(authctxt->service); 1200 packet_put_cstring(authctxt->method->name); 1201 packet_put_string(ap.data, ap.length); 1202 packet_send(); 1203 1204 krb5_data_free(&ap); 1205 return (1); 1206 } 1207 #endif 1208 1209 /* find auth method */ 1210 1211 /* 1212 * given auth method name, if configurable options permit this method fill 1213 * in auth_ident field and return true, otherwise return false. 1214 */ 1215 static int 1216 authmethod_is_enabled(Authmethod *method) 1217 { 1218 if (method == NULL) 1219 return 0; 1220 /* return false if options indicate this method is disabled */ 1221 if (method->enabled == NULL || *method->enabled == 0) 1222 return 0; 1223 /* return false if batch mode is enabled but method needs interactive mode */ 1224 if (method->batch_flag != NULL && *method->batch_flag != 0) 1225 return 0; 1226 return 1; 1227 } 1228 1229 static Authmethod * 1230 authmethod_lookup(const char *name) 1231 { 1232 Authmethod *method = NULL; 1233 if (name != NULL) 1234 for (method = authmethods; method->name != NULL; method++) 1235 if (strcmp(name, method->name) == 0) 1236 return method; 1237 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1238 return NULL; 1239 } 1240 1241 /* XXX internal state */ 1242 static Authmethod *current = NULL; 1243 static char *supported = NULL; 1244 static char *preferred = NULL; 1245 1246 /* 1247 * Given the authentication method list sent by the server, return the 1248 * next method we should try. If the server initially sends a nil list, 1249 * use a built-in default list. 1250 */ 1251 static Authmethod * 1252 authmethod_get(char *authlist) 1253 { 1254 char *name = NULL; 1255 u_int next; 1256 1257 /* Use a suitable default if we're passed a nil list. */ 1258 if (authlist == NULL || strlen(authlist) == 0) 1259 authlist = options.preferred_authentications; 1260 1261 if (supported == NULL || strcmp(authlist, supported) != 0) { 1262 debug3("start over, passed a different list %s", authlist); 1263 if (supported != NULL) 1264 xfree(supported); 1265 supported = xstrdup(authlist); 1266 preferred = options.preferred_authentications; 1267 debug3("preferred %s", preferred); 1268 current = NULL; 1269 } else if (current != NULL && authmethod_is_enabled(current)) 1270 return current; 1271 1272 for (;;) { 1273 if ((name = match_list(preferred, supported, &next)) == NULL) { 1274 debug("No more authentication methods to try."); 1275 current = NULL; 1276 return NULL; 1277 } 1278 preferred += next; 1279 debug3("authmethod_lookup %s", name); 1280 debug3("remaining preferred: %s", preferred); 1281 if ((current = authmethod_lookup(name)) != NULL && 1282 authmethod_is_enabled(current)) { 1283 debug3("authmethod_is_enabled %s", name); 1284 debug("Next authentication method: %s", name); 1285 return current; 1286 } 1287 } 1288 } 1289 1290 static char * 1291 authmethods_get(void) 1292 { 1293 Authmethod *method = NULL; 1294 Buffer b; 1295 char *list; 1296 1297 buffer_init(&b); 1298 for (method = authmethods; method->name != NULL; method++) { 1299 if (authmethod_is_enabled(method)) { 1300 if (buffer_len(&b) > 0) 1301 buffer_append(&b, ",", 1); 1302 buffer_append(&b, method->name, strlen(method->name)); 1303 } 1304 } 1305 buffer_append(&b, "\0", 1); 1306 list = xstrdup(buffer_ptr(&b)); 1307 buffer_free(&b); 1308 return list; 1309 } 1310