sshconnect2.c revision 113911
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" 26RCSID("$OpenBSD: sshconnect2.c,v 1.114 2003/04/01 10:22:21 markus Exp $"); 27RCSID("$FreeBSD: head/crypto/openssh/sshconnect2.c 113911 2003-04-23 17:13:13Z des $"); 28 29#include "ssh.h" 30#include "ssh2.h" 31#include "xmalloc.h" 32#include "buffer.h" 33#include "packet.h" 34#include "compat.h" 35#include "bufaux.h" 36#include "cipher.h" 37#include "kex.h" 38#include "myproposal.h" 39#include "sshconnect.h" 40#include "authfile.h" 41#include "dh.h" 42#include "authfd.h" 43#include "log.h" 44#include "readconf.h" 45#include "readpass.h" 46#include "match.h" 47#include "dispatch.h" 48#include "canohost.h" 49#include "msg.h" 50#include "pathnames.h" 51 52/* import */ 53extern char *client_version_string; 54extern char *server_version_string; 55extern Options options; 56 57/* 58 * SSH2 key exchange 59 */ 60 61u_char *session_id2 = NULL; 62int session_id2_len = 0; 63 64char *xxx_host; 65struct sockaddr *xxx_hostaddr; 66 67Kex *xxx_kex = NULL; 68 69static int 70verify_host_key_callback(Key *hostkey) 71{ 72 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 73 fatal("Host key verification failed."); 74 return 0; 75} 76 77void 78ssh_kex2(char *host, struct sockaddr *hostaddr) 79{ 80 Kex *kex; 81 82 xxx_host = host; 83 xxx_hostaddr = hostaddr; 84 85 if (options.ciphers == (char *)-1) { 86 log("No valid ciphers for protocol version 2 given, using defaults."); 87 options.ciphers = NULL; 88 } 89 if (options.ciphers != NULL) { 90 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 91 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 92 } 93 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 94 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 95 myproposal[PROPOSAL_ENC_ALGS_STOC] = 96 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 97 if (options.compression) { 98 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 99 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none"; 100 } else { 101 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 102 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib"; 103 } 104 if (options.macs != NULL) { 105 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 106 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 107 } 108 if (options.hostkeyalgorithms != NULL) 109 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 110 options.hostkeyalgorithms; 111 112 /* start key exchange */ 113 kex = kex_setup(myproposal); 114 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 115 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 116 kex->client_version_string=client_version_string; 117 kex->server_version_string=server_version_string; 118 kex->verify_host_key=&verify_host_key_callback; 119 120 xxx_kex = kex; 121 122 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 123 124 session_id2 = kex->session_id; 125 session_id2_len = kex->session_id_len; 126 127#ifdef DEBUG_KEXDH 128 /* send 1st encrypted/maced/compressed message */ 129 packet_start(SSH2_MSG_IGNORE); 130 packet_put_cstring("markus"); 131 packet_send(); 132 packet_write_wait(); 133#endif 134} 135 136/* 137 * Authenticate user 138 */ 139 140typedef struct Authctxt Authctxt; 141typedef struct Authmethod Authmethod; 142 143typedef int sign_cb_fn( 144 Authctxt *authctxt, Key *key, 145 u_char **sigp, u_int *lenp, u_char *data, u_int datalen); 146 147struct Authctxt { 148 const char *server_user; 149 const char *local_user; 150 const char *host; 151 const char *service; 152 Authmethod *method; 153 int success; 154 char *authlist; 155 /* pubkey */ 156 Key *last_key; 157 sign_cb_fn *last_key_sign; 158 int last_key_hint; 159 AuthenticationConnection *agent; 160 /* hostbased */ 161 Sensitive *sensitive; 162 /* kbd-interactive */ 163 int info_req_seen; 164}; 165struct Authmethod { 166 char *name; /* string to compare against server's list */ 167 int (*userauth)(Authctxt *authctxt); 168 int *enabled; /* flag in option struct that enables method */ 169 int *batch_flag; /* flag in option struct that disables method */ 170}; 171 172void input_userauth_success(int, u_int32_t, void *); 173void input_userauth_failure(int, u_int32_t, void *); 174void input_userauth_banner(int, u_int32_t, void *); 175void input_userauth_error(int, u_int32_t, void *); 176void input_userauth_info_req(int, u_int32_t, void *); 177void input_userauth_pk_ok(int, u_int32_t, void *); 178void input_userauth_passwd_changereq(int, u_int32_t, void *); 179 180int userauth_none(Authctxt *); 181int userauth_pubkey(Authctxt *); 182int userauth_passwd(Authctxt *); 183int userauth_kbdint(Authctxt *); 184int userauth_hostbased(Authctxt *); 185 186void userauth(Authctxt *, char *); 187 188static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *); 189static void clear_auth_state(Authctxt *); 190 191static Authmethod *authmethod_get(char *authlist); 192static Authmethod *authmethod_lookup(const char *name); 193static char *authmethods_get(void); 194 195Authmethod authmethods[] = { 196 {"hostbased", 197 userauth_hostbased, 198 &options.hostbased_authentication, 199 NULL}, 200 {"publickey", 201 userauth_pubkey, 202 &options.pubkey_authentication, 203 NULL}, 204 {"keyboard-interactive", 205 userauth_kbdint, 206 &options.kbd_interactive_authentication, 207 &options.batch_mode}, 208 {"password", 209 userauth_passwd, 210 &options.password_authentication, 211 &options.batch_mode}, 212 {"none", 213 userauth_none, 214 NULL, 215 NULL}, 216 {NULL, NULL, NULL, NULL} 217}; 218 219void 220ssh_userauth2(const char *local_user, const char *server_user, char *host, 221 Sensitive *sensitive) 222{ 223 Authctxt authctxt; 224 int type; 225 226 if (options.challenge_response_authentication) 227 options.kbd_interactive_authentication = 1; 228 229 packet_start(SSH2_MSG_SERVICE_REQUEST); 230 packet_put_cstring("ssh-userauth"); 231 packet_send(); 232 debug("SSH2_MSG_SERVICE_REQUEST sent"); 233 packet_write_wait(); 234 type = packet_read(); 235 if (type != SSH2_MSG_SERVICE_ACCEPT) 236 fatal("Server denied authentication request: %d", type); 237 if (packet_remaining() > 0) { 238 char *reply = packet_get_string(NULL); 239 debug2("service_accept: %s", reply); 240 xfree(reply); 241 } else { 242 debug2("buggy server: service_accept w/o service"); 243 } 244 packet_check_eom(); 245 debug("SSH2_MSG_SERVICE_ACCEPT received"); 246 247 if (options.preferred_authentications == NULL) 248 options.preferred_authentications = authmethods_get(); 249 250 /* setup authentication context */ 251 memset(&authctxt, 0, sizeof(authctxt)); 252 authctxt.agent = ssh_get_authentication_connection(); 253 authctxt.server_user = server_user; 254 authctxt.local_user = local_user; 255 authctxt.host = host; 256 authctxt.service = "ssh-connection"; /* service name */ 257 authctxt.success = 0; 258 authctxt.method = authmethod_lookup("none"); 259 authctxt.authlist = NULL; 260 authctxt.sensitive = sensitive; 261 authctxt.info_req_seen = 0; 262 if (authctxt.method == NULL) 263 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 264 265 /* initial userauth request */ 266 userauth_none(&authctxt); 267 268 dispatch_init(&input_userauth_error); 269 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 270 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 271 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 272 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 273 274 if (authctxt.agent != NULL) 275 ssh_close_authentication_connection(authctxt.agent); 276 277 debug("Authentication succeeded (%s).", authctxt.method->name); 278} 279void 280userauth(Authctxt *authctxt, char *authlist) 281{ 282 if (authlist == NULL) { 283 authlist = authctxt->authlist; 284 } else { 285 if (authctxt->authlist) 286 xfree(authctxt->authlist); 287 authctxt->authlist = authlist; 288 } 289 for (;;) { 290 Authmethod *method = authmethod_get(authlist); 291 if (method == NULL) 292 fatal("Permission denied (%s).", authlist); 293 authctxt->method = method; 294 if (method->userauth(authctxt) != 0) { 295 debug2("we sent a %s packet, wait for reply", method->name); 296 break; 297 } else { 298 debug2("we did not send a packet, disable method"); 299 method->enabled = NULL; 300 } 301 } 302} 303 304void 305input_userauth_error(int type, u_int32_t seq, void *ctxt) 306{ 307 fatal("input_userauth_error: bad message during authentication: " 308 "type %d", type); 309} 310 311void 312input_userauth_banner(int type, u_int32_t seq, void *ctxt) 313{ 314 char *msg, *lang; 315 debug3("input_userauth_banner"); 316 msg = packet_get_string(NULL); 317 lang = packet_get_string(NULL); 318 fprintf(stderr, "%s", msg); 319 xfree(msg); 320 xfree(lang); 321} 322 323void 324input_userauth_success(int type, u_int32_t seq, void *ctxt) 325{ 326 Authctxt *authctxt = ctxt; 327 if (authctxt == NULL) 328 fatal("input_userauth_success: no authentication context"); 329 if (authctxt->authlist) 330 xfree(authctxt->authlist); 331 clear_auth_state(authctxt); 332 authctxt->success = 1; /* break out */ 333} 334 335void 336input_userauth_failure(int type, u_int32_t seq, void *ctxt) 337{ 338 Authctxt *authctxt = ctxt; 339 char *authlist = NULL; 340 int partial; 341 342 if (authctxt == NULL) 343 fatal("input_userauth_failure: no authentication context"); 344 345 authlist = packet_get_string(NULL); 346 partial = packet_get_char(); 347 packet_check_eom(); 348 349 if (partial != 0) 350 log("Authenticated with partial success."); 351 debug("Authentications that can continue: %s", authlist); 352 353 clear_auth_state(authctxt); 354 userauth(authctxt, authlist); 355} 356void 357input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 358{ 359 Authctxt *authctxt = ctxt; 360 Key *key = NULL; 361 Buffer b; 362 int pktype, sent = 0; 363 u_int alen, blen; 364 char *pkalg, *fp; 365 u_char *pkblob; 366 367 if (authctxt == NULL) 368 fatal("input_userauth_pk_ok: no authentication context"); 369 if (datafellows & SSH_BUG_PKOK) { 370 /* this is similar to SSH_BUG_PKAUTH */ 371 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 372 pkblob = packet_get_string(&blen); 373 buffer_init(&b); 374 buffer_append(&b, pkblob, blen); 375 pkalg = buffer_get_string(&b, &alen); 376 buffer_free(&b); 377 } else { 378 pkalg = packet_get_string(&alen); 379 pkblob = packet_get_string(&blen); 380 } 381 packet_check_eom(); 382 383 debug("Server accepts key: pkalg %s blen %u lastkey %p hint %d", 384 pkalg, blen, authctxt->last_key, authctxt->last_key_hint); 385 386 do { 387 if (authctxt->last_key == NULL || 388 authctxt->last_key_sign == NULL) { 389 debug("no last key or no sign cb"); 390 break; 391 } 392 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 393 debug("unknown pkalg %s", pkalg); 394 break; 395 } 396 if ((key = key_from_blob(pkblob, blen)) == NULL) { 397 debug("no key from blob. pkalg %s", pkalg); 398 break; 399 } 400 if (key->type != pktype) { 401 error("input_userauth_pk_ok: type mismatch " 402 "for decoded key (received %d, expected %d)", 403 key->type, pktype); 404 break; 405 } 406 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 407 debug2("input_userauth_pk_ok: fp %s", fp); 408 xfree(fp); 409 if (!key_equal(key, authctxt->last_key)) { 410 debug("key != last_key"); 411 break; 412 } 413 sent = sign_and_send_pubkey(authctxt, key, 414 authctxt->last_key_sign); 415 } while (0); 416 417 if (key != NULL) 418 key_free(key); 419 xfree(pkalg); 420 xfree(pkblob); 421 422 /* unregister */ 423 clear_auth_state(authctxt); 424 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); 425 426 /* try another method if we did not send a packet */ 427 if (sent == 0) 428 userauth(authctxt, NULL); 429 430} 431 432int 433userauth_none(Authctxt *authctxt) 434{ 435 /* initial userauth request */ 436 packet_start(SSH2_MSG_USERAUTH_REQUEST); 437 packet_put_cstring(authctxt->server_user); 438 packet_put_cstring(authctxt->service); 439 packet_put_cstring(authctxt->method->name); 440 packet_send(); 441 return 1; 442} 443 444int 445userauth_passwd(Authctxt *authctxt) 446{ 447 static int attempt = 0; 448 char prompt[150]; 449 char *password; 450 451 if (attempt++ >= options.number_of_password_prompts) 452 return 0; 453 454 if (attempt != 1) 455 error("Permission denied, please try again."); 456 457 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 458 authctxt->server_user, authctxt->host); 459 password = read_passphrase(prompt, 0); 460 packet_start(SSH2_MSG_USERAUTH_REQUEST); 461 packet_put_cstring(authctxt->server_user); 462 packet_put_cstring(authctxt->service); 463 packet_put_cstring(authctxt->method->name); 464 packet_put_char(0); 465 packet_put_cstring(password); 466 memset(password, 0, strlen(password)); 467 xfree(password); 468 packet_add_padding(64); 469 packet_send(); 470 471 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 472 &input_userauth_passwd_changereq); 473 474 return 1; 475} 476/* 477 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 478 */ 479void 480input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 481{ 482 Authctxt *authctxt = ctxt; 483 char *info, *lang, *password = NULL, *retype = NULL; 484 char prompt[150]; 485 486 debug2("input_userauth_passwd_changereq"); 487 488 if (authctxt == NULL) 489 fatal("input_userauth_passwd_changereq: " 490 "no authentication context"); 491 492 info = packet_get_string(NULL); 493 lang = packet_get_string(NULL); 494 if (strlen(info) > 0) 495 log("%s", info); 496 xfree(info); 497 xfree(lang); 498 packet_start(SSH2_MSG_USERAUTH_REQUEST); 499 packet_put_cstring(authctxt->server_user); 500 packet_put_cstring(authctxt->service); 501 packet_put_cstring(authctxt->method->name); 502 packet_put_char(1); /* additional info */ 503 snprintf(prompt, sizeof(prompt), 504 "Enter %.30s@%.128s's old password: ", 505 authctxt->server_user, authctxt->host); 506 password = read_passphrase(prompt, 0); 507 packet_put_cstring(password); 508 memset(password, 0, strlen(password)); 509 xfree(password); 510 password = NULL; 511 while (password == NULL) { 512 snprintf(prompt, sizeof(prompt), 513 "Enter %.30s@%.128s's new password: ", 514 authctxt->server_user, authctxt->host); 515 password = read_passphrase(prompt, RP_ALLOW_EOF); 516 if (password == NULL) { 517 /* bail out */ 518 return; 519 } 520 snprintf(prompt, sizeof(prompt), 521 "Retype %.30s@%.128s's new password: ", 522 authctxt->server_user, authctxt->host); 523 retype = read_passphrase(prompt, 0); 524 if (strcmp(password, retype) != 0) { 525 memset(password, 0, strlen(password)); 526 xfree(password); 527 log("Mismatch; try again, EOF to quit."); 528 password = NULL; 529 } 530 memset(retype, 0, strlen(retype)); 531 xfree(retype); 532 } 533 packet_put_cstring(password); 534 memset(password, 0, strlen(password)); 535 xfree(password); 536 packet_add_padding(64); 537 packet_send(); 538 539 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 540 &input_userauth_passwd_changereq); 541} 542 543static void 544clear_auth_state(Authctxt *authctxt) 545{ 546 /* XXX clear authentication state */ 547 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL); 548 549 if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { 550 debug3("clear_auth_state: key_free %p", authctxt->last_key); 551 key_free(authctxt->last_key); 552 } 553 authctxt->last_key = NULL; 554 authctxt->last_key_hint = -2; 555 authctxt->last_key_sign = NULL; 556} 557 558static int 559sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) 560{ 561 Buffer b; 562 u_char *blob, *signature; 563 u_int bloblen, slen; 564 int skip = 0; 565 int ret = -1; 566 int have_sig = 1; 567 568 debug3("sign_and_send_pubkey"); 569 570 if (key_to_blob(k, &blob, &bloblen) == 0) { 571 /* we cannot handle this key */ 572 debug3("sign_and_send_pubkey: cannot handle key"); 573 return 0; 574 } 575 /* data to be signed */ 576 buffer_init(&b); 577 if (datafellows & SSH_OLD_SESSIONID) { 578 buffer_append(&b, session_id2, session_id2_len); 579 skip = session_id2_len; 580 } else { 581 buffer_put_string(&b, session_id2, session_id2_len); 582 skip = buffer_len(&b); 583 } 584 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 585 buffer_put_cstring(&b, authctxt->server_user); 586 buffer_put_cstring(&b, 587 datafellows & SSH_BUG_PKSERVICE ? 588 "ssh-userauth" : 589 authctxt->service); 590 if (datafellows & SSH_BUG_PKAUTH) { 591 buffer_put_char(&b, have_sig); 592 } else { 593 buffer_put_cstring(&b, authctxt->method->name); 594 buffer_put_char(&b, have_sig); 595 buffer_put_cstring(&b, key_ssh_name(k)); 596 } 597 buffer_put_string(&b, blob, bloblen); 598 599 /* generate signature */ 600 ret = (*sign_callback)(authctxt, k, &signature, &slen, 601 buffer_ptr(&b), buffer_len(&b)); 602 if (ret == -1) { 603 xfree(blob); 604 buffer_free(&b); 605 return 0; 606 } 607#ifdef DEBUG_PK 608 buffer_dump(&b); 609#endif 610 if (datafellows & SSH_BUG_PKSERVICE) { 611 buffer_clear(&b); 612 buffer_append(&b, session_id2, session_id2_len); 613 skip = session_id2_len; 614 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 615 buffer_put_cstring(&b, authctxt->server_user); 616 buffer_put_cstring(&b, authctxt->service); 617 buffer_put_cstring(&b, authctxt->method->name); 618 buffer_put_char(&b, have_sig); 619 if (!(datafellows & SSH_BUG_PKAUTH)) 620 buffer_put_cstring(&b, key_ssh_name(k)); 621 buffer_put_string(&b, blob, bloblen); 622 } 623 xfree(blob); 624 625 /* append signature */ 626 buffer_put_string(&b, signature, slen); 627 xfree(signature); 628 629 /* skip session id and packet type */ 630 if (buffer_len(&b) < skip + 1) 631 fatal("userauth_pubkey: internal error"); 632 buffer_consume(&b, skip + 1); 633 634 /* put remaining data from buffer into packet */ 635 packet_start(SSH2_MSG_USERAUTH_REQUEST); 636 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 637 buffer_free(&b); 638 packet_send(); 639 640 return 1; 641} 642 643static int 644send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, 645 int hint) 646{ 647 u_char *blob; 648 u_int bloblen, have_sig = 0; 649 650 debug3("send_pubkey_test"); 651 652 if (key_to_blob(k, &blob, &bloblen) == 0) { 653 /* we cannot handle this key */ 654 debug3("send_pubkey_test: cannot handle key"); 655 return 0; 656 } 657 /* register callback for USERAUTH_PK_OK message */ 658 authctxt->last_key_sign = sign_callback; 659 authctxt->last_key_hint = hint; 660 authctxt->last_key = k; 661 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 662 663 packet_start(SSH2_MSG_USERAUTH_REQUEST); 664 packet_put_cstring(authctxt->server_user); 665 packet_put_cstring(authctxt->service); 666 packet_put_cstring(authctxt->method->name); 667 packet_put_char(have_sig); 668 if (!(datafellows & SSH_BUG_PKAUTH)) 669 packet_put_cstring(key_ssh_name(k)); 670 packet_put_string(blob, bloblen); 671 xfree(blob); 672 packet_send(); 673 return 1; 674} 675 676static Key * 677load_identity_file(char *filename) 678{ 679 Key *private; 680 char prompt[300], *passphrase; 681 int quit, i; 682 struct stat st; 683 684 if (stat(filename, &st) < 0) { 685 debug3("no such identity: %s", filename); 686 return NULL; 687 } 688 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 689 if (private == NULL) { 690 if (options.batch_mode) 691 return NULL; 692 snprintf(prompt, sizeof prompt, 693 "Enter passphrase for key '%.100s': ", filename); 694 for (i = 0; i < options.number_of_password_prompts; i++) { 695 passphrase = read_passphrase(prompt, 0); 696 if (strcmp(passphrase, "") != 0) { 697 private = key_load_private_type(KEY_UNSPEC, filename, 698 passphrase, NULL); 699 quit = 0; 700 } else { 701 debug2("no passphrase given, try next key"); 702 quit = 1; 703 } 704 memset(passphrase, 0, strlen(passphrase)); 705 xfree(passphrase); 706 if (private != NULL || quit) 707 break; 708 debug2("bad passphrase given, try again..."); 709 } 710 } 711 return private; 712} 713 714static int 715identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 716 u_char *data, u_int datalen) 717{ 718 Key *private; 719 int idx, ret; 720 721 idx = authctxt->last_key_hint; 722 if (idx < 0) 723 return -1; 724 725 /* private key is stored in external hardware */ 726 if (options.identity_keys[idx]->flags & KEY_FLAG_EXT) 727 return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen); 728 729 private = load_identity_file(options.identity_files[idx]); 730 if (private == NULL) 731 return -1; 732 ret = key_sign(private, sigp, lenp, data, datalen); 733 key_free(private); 734 return ret; 735} 736 737static int 738agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 739 u_char *data, u_int datalen) 740{ 741 return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); 742} 743 744static int 745key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, 746 u_char *data, u_int datalen) 747{ 748 return key_sign(key, sigp, lenp, data, datalen); 749} 750 751static int 752userauth_pubkey_agent(Authctxt *authctxt) 753{ 754 static int called = 0; 755 int ret = 0; 756 char *comment; 757 Key *k; 758 759 if (called == 0) { 760 if (ssh_get_num_identities(authctxt->agent, 2) == 0) 761 debug2("userauth_pubkey_agent: no keys at all"); 762 called = 1; 763 } 764 k = ssh_get_next_identity(authctxt->agent, &comment, 2); 765 if (k == NULL) { 766 debug2("userauth_pubkey_agent: no more keys"); 767 } else { 768 debug("Offering agent key: %s", comment); 769 xfree(comment); 770 ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); 771 if (ret == 0) 772 key_free(k); 773 } 774 if (ret == 0) 775 debug2("userauth_pubkey_agent: no message sent"); 776 return ret; 777} 778 779int 780userauth_pubkey(Authctxt *authctxt) 781{ 782 static int idx = 0; 783 int sent = 0; 784 Key *key; 785 char *filename; 786 787 if (authctxt->agent != NULL) { 788 do { 789 sent = userauth_pubkey_agent(authctxt); 790 } while (!sent && authctxt->agent->howmany > 0); 791 } 792 while (!sent && idx < options.num_identity_files) { 793 key = options.identity_keys[idx]; 794 filename = options.identity_files[idx]; 795 if (key == NULL) { 796 debug("Trying private key: %s", filename); 797 key = load_identity_file(filename); 798 if (key != NULL) { 799 sent = sign_and_send_pubkey(authctxt, key, 800 key_sign_cb); 801 key_free(key); 802 } 803 } else if (key->type != KEY_RSA1) { 804 debug("Offering public key: %s", filename); 805 sent = send_pubkey_test(authctxt, key, 806 identity_sign_cb, idx); 807 } 808 idx++; 809 } 810 return sent; 811} 812 813/* 814 * Send userauth request message specifying keyboard-interactive method. 815 */ 816int 817userauth_kbdint(Authctxt *authctxt) 818{ 819 static int attempt = 0; 820 821 if (attempt++ >= options.number_of_password_prompts) 822 return 0; 823 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 824 if (attempt > 1 && !authctxt->info_req_seen) { 825 debug3("userauth_kbdint: disable: no info_req_seen"); 826 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 827 return 0; 828 } 829 830 debug2("userauth_kbdint"); 831 packet_start(SSH2_MSG_USERAUTH_REQUEST); 832 packet_put_cstring(authctxt->server_user); 833 packet_put_cstring(authctxt->service); 834 packet_put_cstring(authctxt->method->name); 835 packet_put_cstring(""); /* lang */ 836 packet_put_cstring(options.kbd_interactive_devices ? 837 options.kbd_interactive_devices : ""); 838 packet_send(); 839 840 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 841 return 1; 842} 843 844/* 845 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 846 */ 847void 848input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 849{ 850 Authctxt *authctxt = ctxt; 851 char *name, *inst, *lang, *prompt, *response; 852 u_int num_prompts, i; 853 int echo = 0; 854 855 debug2("input_userauth_info_req"); 856 857 if (authctxt == NULL) 858 fatal("input_userauth_info_req: no authentication context"); 859 860 authctxt->info_req_seen = 1; 861 862 name = packet_get_string(NULL); 863 inst = packet_get_string(NULL); 864 lang = packet_get_string(NULL); 865 if (strlen(name) > 0) 866 log("%s", name); 867 if (strlen(inst) > 0) 868 log("%s", inst); 869 xfree(name); 870 xfree(inst); 871 xfree(lang); 872 873 num_prompts = packet_get_int(); 874 /* 875 * Begin to build info response packet based on prompts requested. 876 * We commit to providing the correct number of responses, so if 877 * further on we run into a problem that prevents this, we have to 878 * be sure and clean this up and send a correct error response. 879 */ 880 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 881 packet_put_int(num_prompts); 882 883 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 884 for (i = 0; i < num_prompts; i++) { 885 prompt = packet_get_string(NULL); 886 echo = packet_get_char(); 887 888 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 889 890 packet_put_cstring(response); 891 memset(response, 0, strlen(response)); 892 xfree(response); 893 xfree(prompt); 894 } 895 packet_check_eom(); /* done with parsing incoming message. */ 896 897 packet_add_padding(64); 898 packet_send(); 899} 900 901static int 902ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 903 u_char *data, u_int datalen) 904{ 905 Buffer b; 906 struct stat st; 907 pid_t pid; 908 int to[2], from[2], status, version = 2; 909 910 debug2("ssh_keysign called"); 911 912 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 913 error("ssh_keysign: no installed: %s", strerror(errno)); 914 return -1; 915 } 916 if (fflush(stdout) != 0) 917 error("ssh_keysign: fflush: %s", strerror(errno)); 918 if (pipe(to) < 0) { 919 error("ssh_keysign: pipe: %s", strerror(errno)); 920 return -1; 921 } 922 if (pipe(from) < 0) { 923 error("ssh_keysign: pipe: %s", strerror(errno)); 924 return -1; 925 } 926 if ((pid = fork()) < 0) { 927 error("ssh_keysign: fork: %s", strerror(errno)); 928 return -1; 929 } 930 if (pid == 0) { 931 seteuid(getuid()); 932 setuid(getuid()); 933 close(from[0]); 934 if (dup2(from[1], STDOUT_FILENO) < 0) 935 fatal("ssh_keysign: dup2: %s", strerror(errno)); 936 close(to[1]); 937 if (dup2(to[0], STDIN_FILENO) < 0) 938 fatal("ssh_keysign: dup2: %s", strerror(errno)); 939 close(from[1]); 940 close(to[0]); 941 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 942 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 943 strerror(errno)); 944 } 945 close(from[1]); 946 close(to[0]); 947 948 buffer_init(&b); 949 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 950 buffer_put_string(&b, data, datalen); 951 ssh_msg_send(to[1], version, &b); 952 953 if (ssh_msg_recv(from[0], &b) < 0) { 954 error("ssh_keysign: no reply"); 955 buffer_clear(&b); 956 return -1; 957 } 958 close(from[0]); 959 close(to[1]); 960 961 while (waitpid(pid, &status, 0) < 0) 962 if (errno != EINTR) 963 break; 964 965 if (buffer_get_char(&b) != version) { 966 error("ssh_keysign: bad version"); 967 buffer_clear(&b); 968 return -1; 969 } 970 *sigp = buffer_get_string(&b, lenp); 971 buffer_clear(&b); 972 973 return 0; 974} 975 976int 977userauth_hostbased(Authctxt *authctxt) 978{ 979 Key *private = NULL; 980 Sensitive *sensitive = authctxt->sensitive; 981 Buffer b; 982 u_char *signature, *blob; 983 char *chost, *pkalg, *p; 984 const char *service; 985 u_int blen, slen; 986 int ok, i, len, found = 0; 987 988 /* check for a useful key */ 989 for (i = 0; i < sensitive->nkeys; i++) { 990 private = sensitive->keys[i]; 991 if (private && private->type != KEY_RSA1) { 992 found = 1; 993 /* we take and free the key */ 994 sensitive->keys[i] = NULL; 995 break; 996 } 997 } 998 if (!found) { 999 debug("No more client hostkeys for hostbased authentication."); 1000 return 0; 1001 } 1002 if (key_to_blob(private, &blob, &blen) == 0) { 1003 key_free(private); 1004 return 0; 1005 } 1006 /* figure out a name for the client host */ 1007 p = get_local_name(packet_get_connection_in()); 1008 if (p == NULL) { 1009 error("userauth_hostbased: cannot get local ipaddr/name"); 1010 key_free(private); 1011 return 0; 1012 } 1013 len = strlen(p) + 2; 1014 chost = xmalloc(len); 1015 strlcpy(chost, p, len); 1016 strlcat(chost, ".", len); 1017 debug2("userauth_hostbased: chost %s", chost); 1018 xfree(p); 1019 1020 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1021 authctxt->service; 1022 pkalg = xstrdup(key_ssh_name(private)); 1023 buffer_init(&b); 1024 /* construct data */ 1025 buffer_put_string(&b, session_id2, session_id2_len); 1026 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1027 buffer_put_cstring(&b, authctxt->server_user); 1028 buffer_put_cstring(&b, service); 1029 buffer_put_cstring(&b, authctxt->method->name); 1030 buffer_put_cstring(&b, pkalg); 1031 buffer_put_string(&b, blob, blen); 1032 buffer_put_cstring(&b, chost); 1033 buffer_put_cstring(&b, authctxt->local_user); 1034#ifdef DEBUG_PK 1035 buffer_dump(&b); 1036#endif 1037 if (sensitive->external_keysign) 1038 ok = ssh_keysign(private, &signature, &slen, 1039 buffer_ptr(&b), buffer_len(&b)); 1040 else 1041 ok = key_sign(private, &signature, &slen, 1042 buffer_ptr(&b), buffer_len(&b)); 1043 key_free(private); 1044 buffer_free(&b); 1045 if (ok != 0) { 1046 error("key_sign failed"); 1047 xfree(chost); 1048 xfree(pkalg); 1049 return 0; 1050 } 1051 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1052 packet_put_cstring(authctxt->server_user); 1053 packet_put_cstring(authctxt->service); 1054 packet_put_cstring(authctxt->method->name); 1055 packet_put_cstring(pkalg); 1056 packet_put_string(blob, blen); 1057 packet_put_cstring(chost); 1058 packet_put_cstring(authctxt->local_user); 1059 packet_put_string(signature, slen); 1060 memset(signature, 's', slen); 1061 xfree(signature); 1062 xfree(chost); 1063 xfree(pkalg); 1064 1065 packet_send(); 1066 return 1; 1067} 1068 1069/* find auth method */ 1070 1071/* 1072 * given auth method name, if configurable options permit this method fill 1073 * in auth_ident field and return true, otherwise return false. 1074 */ 1075static int 1076authmethod_is_enabled(Authmethod *method) 1077{ 1078 if (method == NULL) 1079 return 0; 1080 /* return false if options indicate this method is disabled */ 1081 if (method->enabled == NULL || *method->enabled == 0) 1082 return 0; 1083 /* return false if batch mode is enabled but method needs interactive mode */ 1084 if (method->batch_flag != NULL && *method->batch_flag != 0) 1085 return 0; 1086 return 1; 1087} 1088 1089static Authmethod * 1090authmethod_lookup(const char *name) 1091{ 1092 Authmethod *method = NULL; 1093 if (name != NULL) 1094 for (method = authmethods; method->name != NULL; method++) 1095 if (strcmp(name, method->name) == 0) 1096 return method; 1097 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1098 return NULL; 1099} 1100 1101/* XXX internal state */ 1102static Authmethod *current = NULL; 1103static char *supported = NULL; 1104static char *preferred = NULL; 1105 1106/* 1107 * Given the authentication method list sent by the server, return the 1108 * next method we should try. If the server initially sends a nil list, 1109 * use a built-in default list. 1110 */ 1111static Authmethod * 1112authmethod_get(char *authlist) 1113{ 1114 char *name = NULL; 1115 u_int next; 1116 1117 /* Use a suitable default if we're passed a nil list. */ 1118 if (authlist == NULL || strlen(authlist) == 0) 1119 authlist = options.preferred_authentications; 1120 1121 if (supported == NULL || strcmp(authlist, supported) != 0) { 1122 debug3("start over, passed a different list %s", authlist); 1123 if (supported != NULL) 1124 xfree(supported); 1125 supported = xstrdup(authlist); 1126 preferred = options.preferred_authentications; 1127 debug3("preferred %s", preferred); 1128 current = NULL; 1129 } else if (current != NULL && authmethod_is_enabled(current)) 1130 return current; 1131 1132 for (;;) { 1133 if ((name = match_list(preferred, supported, &next)) == NULL) { 1134 debug("No more authentication methods to try."); 1135 current = NULL; 1136 return NULL; 1137 } 1138 preferred += next; 1139 debug3("authmethod_lookup %s", name); 1140 debug3("remaining preferred: %s", preferred); 1141 if ((current = authmethod_lookup(name)) != NULL && 1142 authmethod_is_enabled(current)) { 1143 debug3("authmethod_is_enabled %s", name); 1144 debug("Next authentication method: %s", name); 1145 return current; 1146 } 1147 } 1148} 1149 1150static char * 1151authmethods_get(void) 1152{ 1153 Authmethod *method = NULL; 1154 Buffer b; 1155 char *list; 1156 1157 buffer_init(&b); 1158 for (method = authmethods; method->name != NULL; method++) { 1159 if (authmethod_is_enabled(method)) { 1160 if (buffer_len(&b) > 0) 1161 buffer_append(&b, ",", 1); 1162 buffer_append(&b, method->name, strlen(method->name)); 1163 } 1164 } 1165 buffer_append(&b, "\0", 1); 1166 list = xstrdup(buffer_ptr(&b)); 1167 buffer_free(&b); 1168 return list; 1169} 1170