1 /* $OpenBSD: sshconnect2.c,v 1.330 2020/10/16 02:37:12 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 <stdio.h> 40 #include <string.h> 41 #include <stdarg.h> 42 #include <unistd.h> 43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 44 #include <vis.h> 45 #endif 46 47 #include "openbsd-compat/sys-queue.h" 48 49 #include "xmalloc.h" 50 #include "ssh.h" 51 #include "ssh2.h" 52 #include "sshbuf.h" 53 #include "packet.h" 54 #include "compat.h" 55 #include "cipher.h" 56 #include "sshkey.h" 57 #include "kex.h" 58 #include "myproposal.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "misc.h" 65 #include "readconf.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "ssherr.h" 74 #include "utf8.h" 75 #include "ssh-sk.h" 76 #include "sk-api.h" 77 78 #ifdef GSSAPI 79 #include "ssh-gss.h" 80 #endif 81 82 /* import */ 83 extern char *client_version_string; 84 extern char *server_version_string; 85 extern Options options; 86 87 /* 88 * SSH2 key exchange 89 */ 90 91 u_char *session_id2 = NULL; 92 u_int session_id2_len = 0; 93 94 char *xxx_host; 95 struct sockaddr *xxx_hostaddr; 96 97 static int 98 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 99 { 100 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 101 fatal("Host key verification failed."); 102 return 0; 103 } 104 105 /* Returns the first item from a comma-separated algorithm list */ 106 static char * 107 first_alg(const char *algs) 108 { 109 char *ret, *cp; 110 111 ret = xstrdup(algs); 112 if ((cp = strchr(ret, ',')) != NULL) 113 *cp = '\0'; 114 return ret; 115 } 116 117 static char * 118 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 119 { 120 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 121 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 122 size_t maxlen; 123 struct hostkeys *hostkeys = NULL; 124 int ktype; 125 u_int i; 126 127 /* Find all hostkeys for this hostname */ 128 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 129 hostkeys = init_hostkeys(); 130 for (i = 0; i < options.num_user_hostfiles; i++) 131 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 132 for (i = 0; i < options.num_system_hostfiles; i++) 133 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 134 135 /* 136 * If a plain public key exists that matches the type of the best 137 * preference HostkeyAlgorithms, then use the whole list as is. 138 * Note that we ignore whether the best preference algorithm is a 139 * certificate type, as sshconnect.c will downgrade certs to 140 * plain keys if necessary. 141 */ 142 best = first_alg(options.hostkeyalgorithms); 143 if (lookup_key_in_hostkeys_by_type(hostkeys, 144 sshkey_type_plain(sshkey_type_from_name(best)), 145 sshkey_ecdsa_nid_from_name(best), NULL)) { 146 debug3("%s: have matching best-preference key type %s, " 147 "using HostkeyAlgorithms verbatim", __func__, best); 148 ret = xstrdup(options.hostkeyalgorithms); 149 goto out; 150 } 151 152 /* 153 * Otherwise, prefer the host key algorithms that match known keys 154 * while keeping the ordering of HostkeyAlgorithms as much as possible. 155 */ 156 oavail = avail = xstrdup(options.hostkeyalgorithms); 157 maxlen = strlen(avail) + 1; 158 first = xmalloc(maxlen); 159 last = xmalloc(maxlen); 160 *first = *last = '\0'; 161 162 #define ALG_APPEND(to, from) \ 163 do { \ 164 if (*to != '\0') \ 165 strlcat(to, ",", maxlen); \ 166 strlcat(to, from, maxlen); \ 167 } while (0) 168 169 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 170 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 171 fatal("%s: unknown alg %s", __func__, alg); 172 /* 173 * If we have a @cert-authority marker in known_hosts then 174 * prefer all certificate algorithms. 175 */ 176 if (sshkey_type_is_cert(ktype) && 177 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 178 ALG_APPEND(first, alg); 179 continue; 180 } 181 /* If the key appears in known_hosts then prefer it */ 182 if (lookup_key_in_hostkeys_by_type(hostkeys, 183 sshkey_type_plain(ktype), 184 sshkey_ecdsa_nid_from_name(alg), NULL)) { 185 ALG_APPEND(first, alg); 186 continue; 187 } 188 /* Otherwise, put it last */ 189 ALG_APPEND(last, alg); 190 } 191 #undef ALG_APPEND 192 xasprintf(&ret, "%s%s%s", first, 193 (*first == '\0' || *last == '\0') ? "" : ",", last); 194 if (*first != '\0') 195 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 196 197 out: 198 free(best); 199 free(first); 200 free(last); 201 free(hostname); 202 free(oavail); 203 free_hostkeys(hostkeys); 204 205 return ret; 206 } 207 208 void 209 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 210 { 211 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 212 char *s, *all_key; 213 int r, use_known_hosts_order = 0; 214 215 xxx_host = host; 216 xxx_hostaddr = hostaddr; 217 218 /* 219 * If the user has not specified HostkeyAlgorithms, or has only 220 * appended or removed algorithms from that list then prefer algorithms 221 * that are in the list that are supported by known_hosts keys. 222 */ 223 if (options.hostkeyalgorithms == NULL || 224 options.hostkeyalgorithms[0] == '-' || 225 options.hostkeyalgorithms[0] == '+') 226 use_known_hosts_order = 1; 227 228 /* Expand or fill in HostkeyAlgorithms */ 229 all_key = sshkey_alg_list(0, 0, 1, ','); 230 if (kex_assemble_names(&options.hostkeyalgorithms, 231 kex_default_pk_alg(), all_key) != 0) 232 fatal("%s: kex_assemble_namelist", __func__); 233 free(all_key); 234 235 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 236 fatal("%s: kex_names_cat", __func__); 237 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 238 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 239 compat_cipher_proposal(options.ciphers); 240 myproposal[PROPOSAL_ENC_ALGS_STOC] = 241 compat_cipher_proposal(options.ciphers); 242 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 243 myproposal[PROPOSAL_COMP_ALGS_STOC] = 244 (char *)compression_alg_list(options.compression); 245 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 246 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 247 if (use_known_hosts_order) { 248 /* Query known_hosts and prefer algorithms that appear there */ 249 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 250 compat_pkalg_proposal( 251 order_hostkeyalgs(host, hostaddr, port)); 252 } else { 253 /* Use specified HostkeyAlgorithms exactly */ 254 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 255 compat_pkalg_proposal(options.hostkeyalgorithms); 256 } 257 258 if (options.rekey_limit || options.rekey_interval) 259 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 260 options.rekey_interval); 261 262 /* start key exchange */ 263 if ((r = kex_setup(ssh, myproposal)) != 0) 264 fatal("kex_setup: %s", ssh_err(r)); 265 #ifdef WITH_OPENSSL 266 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 267 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 268 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 269 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 270 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 271 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 272 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 273 # ifdef OPENSSL_HAS_ECC 274 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 275 # endif 276 #endif 277 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 278 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 279 ssh->kex->verify_host_key=&verify_host_key_callback; 280 281 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 282 283 /* remove ext-info from the KEX proposals for rekeying */ 284 myproposal[PROPOSAL_KEX_ALGS] = 285 compat_kex_proposal(options.kex_algorithms); 286 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 287 fatal("kex_prop2buf: %s", ssh_err(r)); 288 289 session_id2 = ssh->kex->session_id; 290 session_id2_len = ssh->kex->session_id_len; 291 292 #ifdef DEBUG_KEXDH 293 /* send 1st encrypted/maced/compressed message */ 294 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 295 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 296 (r = sshpkt_send(ssh)) != 0 || 297 (r = ssh_packet_write_wait(ssh)) != 0) 298 fatal("%s: %s", __func__, ssh_err(r)); 299 #endif 300 } 301 302 /* 303 * Authenticate user 304 */ 305 306 typedef struct cauthctxt Authctxt; 307 typedef struct cauthmethod Authmethod; 308 typedef struct identity Identity; 309 typedef struct idlist Idlist; 310 311 struct identity { 312 TAILQ_ENTRY(identity) next; 313 int agent_fd; /* >=0 if agent supports key */ 314 struct sshkey *key; /* public/private key */ 315 char *filename; /* comment for agent-only keys */ 316 int tried; 317 int isprivate; /* key points to the private key */ 318 int userprovided; 319 }; 320 TAILQ_HEAD(idlist, identity); 321 322 struct cauthctxt { 323 const char *server_user; 324 const char *local_user; 325 const char *host; 326 const char *service; 327 struct cauthmethod *method; 328 sig_atomic_t success; 329 char *authlist; 330 #ifdef GSSAPI 331 /* gssapi */ 332 gss_OID_set gss_supported_mechs; 333 u_int mech_tried; 334 #endif 335 /* pubkey */ 336 struct idlist keys; 337 int agent_fd; 338 /* hostbased */ 339 Sensitive *sensitive; 340 char *oktypes, *ktypes; 341 const char *active_ktype; 342 /* kbd-interactive */ 343 int info_req_seen; 344 int attempt_kbdint; 345 /* password */ 346 int attempt_passwd; 347 /* generic */ 348 void *methoddata; 349 }; 350 351 struct cauthmethod { 352 char *name; /* string to compare against server's list */ 353 int (*userauth)(struct ssh *ssh); 354 void (*cleanup)(struct ssh *ssh); 355 int *enabled; /* flag in option struct that enables method */ 356 int *batch_flag; /* flag in option struct that disables method */ 357 }; 358 359 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 360 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 361 static int input_userauth_success(int, u_int32_t, struct ssh *); 362 static int input_userauth_failure(int, u_int32_t, struct ssh *); 363 static int input_userauth_banner(int, u_int32_t, struct ssh *); 364 static int input_userauth_error(int, u_int32_t, struct ssh *); 365 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 366 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 367 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 368 369 static int userauth_none(struct ssh *); 370 static int userauth_pubkey(struct ssh *); 371 static int userauth_passwd(struct ssh *); 372 static int userauth_kbdint(struct ssh *); 373 static int userauth_hostbased(struct ssh *); 374 375 #ifdef GSSAPI 376 static int userauth_gssapi(struct ssh *); 377 static void userauth_gssapi_cleanup(struct ssh *); 378 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 379 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 380 static int input_gssapi_error(int, u_int32_t, struct ssh *); 381 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 382 #endif 383 384 void userauth(struct ssh *, char *); 385 386 static void pubkey_cleanup(struct ssh *); 387 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 388 static void pubkey_prepare(Authctxt *); 389 static void pubkey_reset(Authctxt *); 390 static struct sshkey *load_identity_file(Identity *); 391 392 static Authmethod *authmethod_get(char *authlist); 393 static Authmethod *authmethod_lookup(const char *name); 394 static char *authmethods_get(void); 395 396 Authmethod authmethods[] = { 397 #ifdef GSSAPI 398 {"gssapi-with-mic", 399 userauth_gssapi, 400 userauth_gssapi_cleanup, 401 &options.gss_authentication, 402 NULL}, 403 #endif 404 {"hostbased", 405 userauth_hostbased, 406 NULL, 407 &options.hostbased_authentication, 408 NULL}, 409 {"publickey", 410 userauth_pubkey, 411 NULL, 412 &options.pubkey_authentication, 413 NULL}, 414 {"keyboard-interactive", 415 userauth_kbdint, 416 NULL, 417 &options.kbd_interactive_authentication, 418 &options.batch_mode}, 419 {"password", 420 userauth_passwd, 421 NULL, 422 &options.password_authentication, 423 &options.batch_mode}, 424 {"none", 425 userauth_none, 426 NULL, 427 NULL, 428 NULL}, 429 {NULL, NULL, NULL, NULL, NULL} 430 }; 431 432 void 433 ssh_userauth2(struct ssh *ssh, const char *local_user, 434 const char *server_user, char *host, Sensitive *sensitive) 435 { 436 Authctxt authctxt; 437 int r; 438 439 if (options.challenge_response_authentication) 440 options.kbd_interactive_authentication = 1; 441 if (options.preferred_authentications == NULL) 442 options.preferred_authentications = authmethods_get(); 443 444 /* setup authentication context */ 445 memset(&authctxt, 0, sizeof(authctxt)); 446 authctxt.server_user = server_user; 447 authctxt.local_user = local_user; 448 authctxt.host = host; 449 authctxt.service = "ssh-connection"; /* service name */ 450 authctxt.success = 0; 451 authctxt.method = authmethod_lookup("none"); 452 authctxt.authlist = NULL; 453 authctxt.methoddata = NULL; 454 authctxt.sensitive = sensitive; 455 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 456 authctxt.info_req_seen = 0; 457 authctxt.attempt_kbdint = 0; 458 authctxt.attempt_passwd = 0; 459 #if GSSAPI 460 authctxt.gss_supported_mechs = NULL; 461 authctxt.mech_tried = 0; 462 #endif 463 authctxt.agent_fd = -1; 464 pubkey_prepare(&authctxt); 465 if (authctxt.method == NULL) { 466 fatal("%s: internal error: cannot send userauth none request", 467 __func__); 468 } 469 470 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 471 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 472 (r = sshpkt_send(ssh)) != 0) 473 fatal("%s: %s", __func__, ssh_err(r)); 474 475 ssh->authctxt = &authctxt; 476 ssh_dispatch_init(ssh, &input_userauth_error); 477 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 478 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 479 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 480 pubkey_cleanup(ssh); 481 ssh->authctxt = NULL; 482 483 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 484 485 if (!authctxt.success) 486 fatal("Authentication failed."); 487 debug("Authentication succeeded (%s).", authctxt.method->name); 488 } 489 490 /* ARGSUSED */ 491 static int 492 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 493 { 494 int r; 495 496 if (ssh_packet_remaining(ssh) > 0) { 497 char *reply; 498 499 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 500 goto out; 501 debug2("service_accept: %s", reply); 502 free(reply); 503 } else { 504 debug2("buggy server: service_accept w/o service"); 505 } 506 if ((r = sshpkt_get_end(ssh)) != 0) 507 goto out; 508 debug("SSH2_MSG_SERVICE_ACCEPT received"); 509 510 /* initial userauth request */ 511 userauth_none(ssh); 512 513 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 514 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 515 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 516 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 517 r = 0; 518 out: 519 return r; 520 } 521 522 /* ARGSUSED */ 523 static int 524 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 525 { 526 return kex_input_ext_info(type, seqnr, ssh); 527 } 528 529 void 530 userauth(struct ssh *ssh, char *authlist) 531 { 532 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 533 534 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 535 authctxt->method->cleanup(ssh); 536 537 free(authctxt->methoddata); 538 authctxt->methoddata = NULL; 539 if (authlist == NULL) { 540 authlist = authctxt->authlist; 541 } else { 542 free(authctxt->authlist); 543 authctxt->authlist = authlist; 544 } 545 for (;;) { 546 Authmethod *method = authmethod_get(authlist); 547 if (method == NULL) 548 fatal("%s@%s: Permission denied (%s).", 549 authctxt->server_user, authctxt->host, authlist); 550 authctxt->method = method; 551 552 /* reset the per method handler */ 553 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 554 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 555 556 /* and try new method */ 557 if (method->userauth(ssh) != 0) { 558 debug2("we sent a %s packet, wait for reply", method->name); 559 break; 560 } else { 561 debug2("we did not send a packet, disable method"); 562 method->enabled = NULL; 563 } 564 } 565 } 566 567 /* ARGSUSED */ 568 static int 569 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 570 { 571 fatal("%s: bad message during authentication: type %d", __func__, type); 572 return 0; 573 } 574 575 /* ARGSUSED */ 576 static int 577 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 578 { 579 char *msg = NULL; 580 size_t len; 581 int r; 582 583 debug3("%s", __func__); 584 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 585 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 586 goto out; 587 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 588 fmprintf(stderr, "%s", msg); 589 r = 0; 590 out: 591 free(msg); 592 return r; 593 } 594 595 /* ARGSUSED */ 596 static int 597 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 598 { 599 Authctxt *authctxt = ssh->authctxt; 600 601 if (authctxt == NULL) 602 fatal("%s: no authentication context", __func__); 603 free(authctxt->authlist); 604 authctxt->authlist = NULL; 605 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 606 authctxt->method->cleanup(ssh); 607 free(authctxt->methoddata); 608 authctxt->methoddata = NULL; 609 authctxt->success = 1; /* break out */ 610 return 0; 611 } 612 613 #if 0 614 static int 615 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 616 { 617 Authctxt *authctxt = ssh->authctxt; 618 619 if (authctxt == NULL) 620 fatal("%s: no authentication context", __func__); 621 622 fatal("Unexpected authentication success during %s.", 623 authctxt->method->name); 624 return 0; 625 } 626 #endif 627 628 /* ARGSUSED */ 629 static int 630 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 631 { 632 Authctxt *authctxt = ssh->authctxt; 633 char *authlist = NULL; 634 u_char partial; 635 636 if (authctxt == NULL) 637 fatal("input_userauth_failure: no authentication context"); 638 639 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 640 sshpkt_get_u8(ssh, &partial) != 0 || 641 sshpkt_get_end(ssh) != 0) 642 goto out; 643 644 if (partial != 0) { 645 verbose("Authenticated with partial success."); 646 /* reset state */ 647 pubkey_reset(authctxt); 648 } 649 debug("Authentications that can continue: %s", authlist); 650 651 userauth(ssh, authlist); 652 authlist = NULL; 653 out: 654 free(authlist); 655 return 0; 656 } 657 658 /* 659 * Format an identity for logging including filename, key type, fingerprint 660 * and location (agent, etc.). Caller must free. 661 */ 662 static char * 663 format_identity(Identity *id) 664 { 665 char *fp = NULL, *ret = NULL; 666 const char *note = ""; 667 668 if (id->key != NULL) { 669 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 670 SSH_FP_DEFAULT); 671 } 672 if (id->key) { 673 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 674 note = " token"; 675 else if (sshkey_is_sk(id->key)) 676 note = " authenticator"; 677 } 678 xasprintf(&ret, "%s %s%s%s%s%s%s", 679 id->filename, 680 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 681 fp ? fp : "", 682 id->userprovided ? " explicit" : "", note, 683 id->agent_fd != -1 ? " agent" : ""); 684 free(fp); 685 return ret; 686 } 687 688 /* ARGSUSED */ 689 static int 690 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 691 { 692 Authctxt *authctxt = ssh->authctxt; 693 struct sshkey *key = NULL; 694 Identity *id = NULL; 695 int pktype, found = 0, sent = 0; 696 size_t blen; 697 char *pkalg = NULL, *fp = NULL, *ident = NULL; 698 u_char *pkblob = NULL; 699 int r; 700 701 if (authctxt == NULL) 702 fatal("input_userauth_pk_ok: no authentication context"); 703 704 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 705 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 706 (r = sshpkt_get_end(ssh)) != 0) 707 goto done; 708 709 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 710 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 711 goto done; 712 } 713 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 714 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 715 goto done; 716 } 717 if (key->type != pktype) { 718 error("input_userauth_pk_ok: type mismatch " 719 "for decoded key (received %d, expected %d)", 720 key->type, pktype); 721 goto done; 722 } 723 724 /* 725 * search keys in the reverse order, because last candidate has been 726 * moved to the end of the queue. this also avoids confusion by 727 * duplicate keys 728 */ 729 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 730 if (sshkey_equal(key, id->key)) { 731 found = 1; 732 break; 733 } 734 } 735 if (!found || id == NULL) { 736 fp = sshkey_fingerprint(key, options.fingerprint_hash, 737 SSH_FP_DEFAULT); 738 error("%s: server replied with unknown key: %s %s", __func__, 739 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 740 goto done; 741 } 742 ident = format_identity(id); 743 debug("Server accepts key: %s", ident); 744 sent = sign_and_send_pubkey(ssh, id); 745 r = 0; 746 done: 747 sshkey_free(key); 748 free(ident); 749 free(fp); 750 free(pkalg); 751 free(pkblob); 752 753 /* try another method if we did not send a packet */ 754 if (r == 0 && sent == 0) 755 userauth(ssh, NULL); 756 return r; 757 } 758 759 #ifdef GSSAPI 760 static int 761 userauth_gssapi(struct ssh *ssh) 762 { 763 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 764 Gssctxt *gssctxt = NULL; 765 OM_uint32 min; 766 int r, ok = 0; 767 gss_OID mech = NULL; 768 769 /* Try one GSSAPI method at a time, rather than sending them all at 770 * once. */ 771 772 if (authctxt->gss_supported_mechs == NULL) 773 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 774 775 /* Check to see whether the mechanism is usable before we offer it */ 776 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 777 !ok) { 778 mech = &authctxt->gss_supported_mechs-> 779 elements[authctxt->mech_tried]; 780 /* My DER encoding requires length<128 */ 781 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 782 mech, authctxt->host)) { 783 ok = 1; /* Mechanism works */ 784 } else { 785 authctxt->mech_tried++; 786 } 787 } 788 789 if (!ok || mech == NULL) 790 return 0; 791 792 authctxt->methoddata=(void *)gssctxt; 793 794 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 795 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 796 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 797 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 798 (r = sshpkt_put_u32(ssh, 1)) != 0 || 799 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 800 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 801 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 802 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 803 (r = sshpkt_send(ssh)) != 0) 804 fatal("%s: %s", __func__, ssh_err(r)); 805 806 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 807 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 808 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 809 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 810 811 authctxt->mech_tried++; /* Move along to next candidate */ 812 813 return 1; 814 } 815 816 static void 817 userauth_gssapi_cleanup(struct ssh *ssh) 818 { 819 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 820 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 821 822 ssh_gssapi_delete_ctx(&gssctxt); 823 authctxt->methoddata = NULL; 824 825 free(authctxt->gss_supported_mechs); 826 authctxt->gss_supported_mechs = NULL; 827 } 828 829 static OM_uint32 830 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 831 { 832 Authctxt *authctxt = ssh->authctxt; 833 Gssctxt *gssctxt = authctxt->methoddata; 834 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 835 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 836 gss_buffer_desc gssbuf; 837 OM_uint32 status, ms, flags; 838 int r; 839 840 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 841 recv_tok, &send_tok, &flags); 842 843 if (send_tok.length > 0) { 844 u_char type = GSS_ERROR(status) ? 845 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 846 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 847 848 if ((r = sshpkt_start(ssh, type)) != 0 || 849 (r = sshpkt_put_string(ssh, send_tok.value, 850 send_tok.length)) != 0 || 851 (r = sshpkt_send(ssh)) != 0) 852 fatal("%s: %s", __func__, ssh_err(r)); 853 854 gss_release_buffer(&ms, &send_tok); 855 } 856 857 if (status == GSS_S_COMPLETE) { 858 /* send either complete or MIC, depending on mechanism */ 859 if (!(flags & GSS_C_INTEG_FLAG)) { 860 if ((r = sshpkt_start(ssh, 861 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 862 (r = sshpkt_send(ssh)) != 0) 863 fatal("%s: %s", __func__, ssh_err(r)); 864 } else { 865 struct sshbuf *b; 866 867 if ((b = sshbuf_new()) == NULL) 868 fatal("%s: sshbuf_new failed", __func__); 869 ssh_gssapi_buildmic(b, authctxt->server_user, 870 authctxt->service, "gssapi-with-mic"); 871 872 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 873 fatal("%s: sshbuf_mutable_ptr failed", __func__); 874 gssbuf.length = sshbuf_len(b); 875 876 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 877 878 if (!GSS_ERROR(status)) { 879 if ((r = sshpkt_start(ssh, 880 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 881 (r = sshpkt_put_string(ssh, mic.value, 882 mic.length)) != 0 || 883 (r = sshpkt_send(ssh)) != 0) 884 fatal("%s: %s", __func__, ssh_err(r)); 885 } 886 887 sshbuf_free(b); 888 gss_release_buffer(&ms, &mic); 889 } 890 } 891 892 return status; 893 } 894 895 /* ARGSUSED */ 896 static int 897 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 898 { 899 Authctxt *authctxt = ssh->authctxt; 900 Gssctxt *gssctxt; 901 size_t oidlen; 902 u_char *oidv = NULL; 903 int r; 904 905 if (authctxt == NULL) 906 fatal("input_gssapi_response: no authentication context"); 907 gssctxt = authctxt->methoddata; 908 909 /* Setup our OID */ 910 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 911 goto done; 912 913 if (oidlen <= 2 || 914 oidv[0] != SSH_GSS_OIDTYPE || 915 oidv[1] != oidlen - 2) { 916 debug("Badly encoded mechanism OID received"); 917 userauth(ssh, NULL); 918 goto ok; 919 } 920 921 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 922 fatal("Server returned different OID than expected"); 923 924 if ((r = sshpkt_get_end(ssh)) != 0) 925 goto done; 926 927 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 928 /* Start again with next method on list */ 929 debug("Trying to start again"); 930 userauth(ssh, NULL); 931 goto ok; 932 } 933 ok: 934 r = 0; 935 done: 936 free(oidv); 937 return r; 938 } 939 940 /* ARGSUSED */ 941 static int 942 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 943 { 944 Authctxt *authctxt = ssh->authctxt; 945 gss_buffer_desc recv_tok; 946 u_char *p = NULL; 947 size_t len; 948 OM_uint32 status; 949 int r; 950 951 if (authctxt == NULL) 952 fatal("input_gssapi_response: no authentication context"); 953 954 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 955 (r = sshpkt_get_end(ssh)) != 0) 956 goto out; 957 958 recv_tok.value = p; 959 recv_tok.length = len; 960 status = process_gssapi_token(ssh, &recv_tok); 961 962 /* Start again with the next method in the list */ 963 if (GSS_ERROR(status)) { 964 userauth(ssh, NULL); 965 /* ok */ 966 } 967 r = 0; 968 out: 969 free(p); 970 return r; 971 } 972 973 /* ARGSUSED */ 974 static int 975 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 976 { 977 Authctxt *authctxt = ssh->authctxt; 978 Gssctxt *gssctxt; 979 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 980 gss_buffer_desc recv_tok; 981 OM_uint32 ms; 982 u_char *p = NULL; 983 size_t len; 984 int r; 985 986 if (authctxt == NULL) 987 fatal("input_gssapi_response: no authentication context"); 988 gssctxt = authctxt->methoddata; 989 990 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 991 (r = sshpkt_get_end(ssh)) != 0) { 992 free(p); 993 return r; 994 } 995 996 /* Stick it into GSSAPI and see what it says */ 997 recv_tok.value = p; 998 recv_tok.length = len; 999 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1000 &recv_tok, &send_tok, NULL); 1001 free(p); 1002 gss_release_buffer(&ms, &send_tok); 1003 1004 /* Server will be returning a failed packet after this one */ 1005 return 0; 1006 } 1007 1008 /* ARGSUSED */ 1009 static int 1010 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1011 { 1012 char *msg = NULL; 1013 char *lang = NULL; 1014 int r; 1015 1016 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1017 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1018 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1019 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1020 goto out; 1021 r = sshpkt_get_end(ssh); 1022 debug("Server GSSAPI Error:\n%s", msg); 1023 out: 1024 free(msg); 1025 free(lang); 1026 return r; 1027 } 1028 #endif /* GSSAPI */ 1029 1030 static int 1031 userauth_none(struct ssh *ssh) 1032 { 1033 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1034 int r; 1035 1036 /* initial userauth request */ 1037 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1038 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1039 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1040 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1041 (r = sshpkt_send(ssh)) != 0) 1042 fatal("%s: %s", __func__, ssh_err(r)); 1043 return 1; 1044 } 1045 1046 static int 1047 userauth_passwd(struct ssh *ssh) 1048 { 1049 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1050 char *password, *prompt = NULL; 1051 const char *host = options.host_key_alias ? options.host_key_alias : 1052 authctxt->host; 1053 int r; 1054 1055 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1056 return 0; 1057 1058 if (authctxt->attempt_passwd != 1) 1059 error("Permission denied, please try again."); 1060 1061 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1062 password = read_passphrase(prompt, 0); 1063 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1064 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1065 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1066 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1067 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1068 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1069 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1070 (r = sshpkt_send(ssh)) != 0) 1071 fatal("%s: %s", __func__, ssh_err(r)); 1072 1073 free(prompt); 1074 if (password != NULL) 1075 freezero(password, strlen(password)); 1076 1077 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1078 &input_userauth_passwd_changereq); 1079 1080 return 1; 1081 } 1082 1083 /* 1084 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1085 */ 1086 /* ARGSUSED */ 1087 static int 1088 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1089 { 1090 Authctxt *authctxt = ssh->authctxt; 1091 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1092 char prompt[256]; 1093 const char *host; 1094 int r; 1095 1096 debug2("input_userauth_passwd_changereq"); 1097 1098 if (authctxt == NULL) 1099 fatal("input_userauth_passwd_changereq: " 1100 "no authentication context"); 1101 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1102 1103 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1104 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1105 goto out; 1106 if (strlen(info) > 0) 1107 logit("%s", info); 1108 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1109 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1110 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1111 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1112 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1113 goto out; 1114 1115 snprintf(prompt, sizeof(prompt), 1116 "Enter %.30s@%.128s's old password: ", 1117 authctxt->server_user, host); 1118 password = read_passphrase(prompt, 0); 1119 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1120 goto out; 1121 1122 freezero(password, strlen(password)); 1123 password = NULL; 1124 while (password == NULL) { 1125 snprintf(prompt, sizeof(prompt), 1126 "Enter %.30s@%.128s's new password: ", 1127 authctxt->server_user, host); 1128 password = read_passphrase(prompt, RP_ALLOW_EOF); 1129 if (password == NULL) { 1130 /* bail out */ 1131 r = 0; 1132 goto out; 1133 } 1134 snprintf(prompt, sizeof(prompt), 1135 "Retype %.30s@%.128s's new password: ", 1136 authctxt->server_user, host); 1137 retype = read_passphrase(prompt, 0); 1138 if (strcmp(password, retype) != 0) { 1139 freezero(password, strlen(password)); 1140 logit("Mismatch; try again, EOF to quit."); 1141 password = NULL; 1142 } 1143 freezero(retype, strlen(retype)); 1144 } 1145 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1146 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1147 (r = sshpkt_send(ssh)) != 0) 1148 goto out; 1149 1150 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1151 &input_userauth_passwd_changereq); 1152 r = 0; 1153 out: 1154 if (password) 1155 freezero(password, strlen(password)); 1156 free(info); 1157 free(lang); 1158 return r; 1159 } 1160 1161 /* 1162 * Select an algorithm for publickey signatures. 1163 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1164 * 1165 * Call with ssh==NULL to ignore server-sig-algs extension list and 1166 * only attempt with the key's base signature type. 1167 */ 1168 static char * 1169 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1170 { 1171 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1172 1173 /* 1174 * The signature algorithm will only differ from the key algorithm 1175 * for RSA keys/certs and when the server advertises support for 1176 * newer (SHA2) algorithms. 1177 */ 1178 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1179 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1180 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1181 /* Filter base key signature alg against our configuration */ 1182 return match_list(sshkey_ssh_name(key), 1183 options.pubkey_key_types, NULL); 1184 } 1185 1186 /* 1187 * For RSA keys/certs, since these might have a different sig type: 1188 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1189 * that also appears in the supported signature algorithms list from 1190 * the server. 1191 */ 1192 oallowed = allowed = xstrdup(options.pubkey_key_types); 1193 while ((cp = strsep(&allowed, ",")) != NULL) { 1194 if (sshkey_type_from_name(cp) != key->type) 1195 continue; 1196 tmp = match_list(sshkey_sigalg_by_name(cp), 1197 ssh->kex->server_sig_algs, NULL); 1198 if (tmp != NULL) 1199 alg = xstrdup(cp); 1200 free(tmp); 1201 if (alg != NULL) 1202 break; 1203 } 1204 free(oallowed); 1205 return alg; 1206 } 1207 1208 static int 1209 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1210 const u_char *data, size_t datalen, u_int compat, const char *alg) 1211 { 1212 struct sshkey *sign_key = NULL, *prv = NULL; 1213 int r = SSH_ERR_INTERNAL_ERROR; 1214 struct notifier_ctx *notifier = NULL; 1215 char *fp = NULL, *pin = NULL, *prompt = NULL; 1216 1217 *sigp = NULL; 1218 *lenp = 0; 1219 1220 /* The agent supports this key. */ 1221 if (id->key != NULL && id->agent_fd != -1) { 1222 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1223 data, datalen, alg, compat); 1224 } 1225 1226 /* 1227 * We have already loaded the private key or the private key is 1228 * stored in external hardware. 1229 */ 1230 if (id->key != NULL && 1231 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1232 sign_key = id->key; 1233 } else { 1234 /* Load the private key from the file. */ 1235 if ((prv = load_identity_file(id)) == NULL) 1236 return SSH_ERR_KEY_NOT_FOUND; 1237 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1238 error("%s: private key %s contents do not match public", 1239 __func__, id->filename); 1240 r = SSH_ERR_KEY_NOT_FOUND; 1241 goto out; 1242 } 1243 sign_key = prv; 1244 if (sshkey_is_sk(sign_key)) { 1245 if ((sign_key->sk_flags & 1246 SSH_SK_USER_VERIFICATION_REQD)) { 1247 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1248 sshkey_type(sign_key), id->filename); 1249 pin = read_passphrase(prompt, 0); 1250 } 1251 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1252 /* XXX should batch mode just skip these? */ 1253 if ((fp = sshkey_fingerprint(sign_key, 1254 options.fingerprint_hash, 1255 SSH_FP_DEFAULT)) == NULL) 1256 fatal("%s: fingerprint", __func__); 1257 notifier = notify_start(options.batch_mode, 1258 "Confirm user presence for key %s %s", 1259 sshkey_type(sign_key), fp); 1260 free(fp); 1261 } 1262 } 1263 } 1264 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1265 alg, options.sk_provider, pin, compat)) != 0) { 1266 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1267 goto out; 1268 } 1269 /* 1270 * PKCS#11 tokens may not support all signature algorithms, 1271 * so check what we get back. 1272 */ 1273 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1274 debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r)); 1275 goto out; 1276 } 1277 /* success */ 1278 r = 0; 1279 out: 1280 free(prompt); 1281 if (pin != NULL) 1282 freezero(pin, strlen(pin)); 1283 notify_complete(notifier); 1284 sshkey_free(prv); 1285 return r; 1286 } 1287 1288 static int 1289 id_filename_matches(Identity *id, Identity *private_id) 1290 { 1291 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1292 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1293 size_t i, slen; 1294 1295 if (strcmp(id->filename, private_id->filename) == 0) 1296 return 1; 1297 for (i = 0; suffixes[i]; i++) { 1298 slen = strlen(suffixes[i]); 1299 if (len > slen && plen == len - slen && 1300 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1301 memcmp(id->filename, private_id->filename, plen) == 0) 1302 return 1; 1303 } 1304 return 0; 1305 } 1306 1307 static int 1308 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1309 { 1310 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1311 struct sshbuf *b = NULL; 1312 Identity *private_id, *sign_id = NULL; 1313 u_char *signature = NULL; 1314 size_t slen = 0, skip = 0; 1315 int r, fallback_sigtype, sent = 0; 1316 char *alg = NULL, *fp = NULL; 1317 const char *loc = ""; 1318 1319 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1320 SSH_FP_DEFAULT)) == NULL) 1321 return 0; 1322 1323 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1324 1325 /* 1326 * If the key is an certificate, try to find a matching private key 1327 * and use it to complete the signature. 1328 * If no such private key exists, fall back to trying the certificate 1329 * key itself in case it has a private half already loaded. 1330 * This will try to set sign_id to the private key that will perform 1331 * the signature. 1332 */ 1333 if (sshkey_is_cert(id->key)) { 1334 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1335 if (sshkey_equal_public(id->key, private_id->key) && 1336 id->key->type != private_id->key->type) { 1337 sign_id = private_id; 1338 break; 1339 } 1340 } 1341 /* 1342 * Exact key matches are preferred, but also allow 1343 * filename matches for non-PKCS#11/agent keys that 1344 * didn't load public keys. This supports the case 1345 * of keeping just a private key file and public 1346 * certificate on disk. 1347 */ 1348 if (sign_id == NULL && 1349 !id->isprivate && id->agent_fd == -1 && 1350 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1351 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1352 if (private_id->key == NULL && 1353 id_filename_matches(id, private_id)) { 1354 sign_id = private_id; 1355 break; 1356 } 1357 } 1358 } 1359 if (sign_id != NULL) { 1360 debug2("%s: using private key \"%s\"%s for " 1361 "certificate", __func__, id->filename, 1362 id->agent_fd != -1 ? " from agent" : ""); 1363 } else { 1364 debug("%s: no separate private key for certificate " 1365 "\"%s\"", __func__, id->filename); 1366 } 1367 } 1368 1369 /* 1370 * If the above didn't select another identity to do the signing 1371 * then default to the one we started with. 1372 */ 1373 if (sign_id == NULL) 1374 sign_id = id; 1375 1376 /* assemble and sign data */ 1377 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1378 free(alg); 1379 slen = 0; 1380 signature = NULL; 1381 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1382 id->key)) == NULL) { 1383 error("%s: no mutual signature supported", __func__); 1384 goto out; 1385 } 1386 debug3("%s: signing using %s %s", __func__, alg, fp); 1387 1388 sshbuf_free(b); 1389 if ((b = sshbuf_new()) == NULL) 1390 fatal("%s: sshbuf_new failed", __func__); 1391 if (datafellows & SSH_OLD_SESSIONID) { 1392 if ((r = sshbuf_put(b, session_id2, 1393 session_id2_len)) != 0) { 1394 fatal("%s: sshbuf_put: %s", 1395 __func__, ssh_err(r)); 1396 } 1397 } else { 1398 if ((r = sshbuf_put_string(b, session_id2, 1399 session_id2_len)) != 0) { 1400 fatal("%s: sshbuf_put_string: %s", 1401 __func__, ssh_err(r)); 1402 } 1403 } 1404 skip = sshbuf_len(b); 1405 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1406 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1407 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1408 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1409 (r = sshbuf_put_u8(b, 1)) != 0 || 1410 (r = sshbuf_put_cstring(b, alg)) != 0 || 1411 (r = sshkey_puts(id->key, b)) != 0) { 1412 fatal("%s: assemble signed data: %s", 1413 __func__, ssh_err(r)); 1414 } 1415 1416 /* generate signature */ 1417 r = identity_sign(sign_id, &signature, &slen, 1418 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1419 if (r == 0) 1420 break; 1421 else if (r == SSH_ERR_KEY_NOT_FOUND) 1422 goto out; /* soft failure */ 1423 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1424 !fallback_sigtype) { 1425 if (sign_id->agent_fd != -1) 1426 loc = "agent "; 1427 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1428 loc = "token "; 1429 logit("%skey %s %s returned incorrect signature type", 1430 loc, sshkey_type(id->key), fp); 1431 continue; 1432 } 1433 error("%s: signing failed for %s \"%s\"%s: %s", __func__, 1434 sshkey_type(sign_id->key), sign_id->filename, 1435 id->agent_fd != -1 ? " from agent" : "", ssh_err(r)); 1436 goto out; 1437 } 1438 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1439 fatal("%s: no signature", __func__); 1440 1441 /* append signature */ 1442 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1443 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1444 1445 #ifdef DEBUG_PK 1446 sshbuf_dump(b, stderr); 1447 #endif 1448 /* skip session id and packet type */ 1449 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1450 fatal("%s: consume: %s", __func__, ssh_err(r)); 1451 1452 /* put remaining data from buffer into packet */ 1453 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1454 (r = sshpkt_putb(ssh, b)) != 0 || 1455 (r = sshpkt_send(ssh)) != 0) 1456 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1457 1458 /* success */ 1459 sent = 1; 1460 1461 out: 1462 free(fp); 1463 free(alg); 1464 sshbuf_free(b); 1465 freezero(signature, slen); 1466 return sent; 1467 } 1468 1469 static int 1470 send_pubkey_test(struct ssh *ssh, Identity *id) 1471 { 1472 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1473 u_char *blob = NULL; 1474 char *alg = NULL; 1475 size_t bloblen; 1476 u_int have_sig = 0; 1477 int sent = 0, r; 1478 1479 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1480 debug("%s: no mutual signature algorithm", __func__); 1481 goto out; 1482 } 1483 1484 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1485 /* we cannot handle this key */ 1486 debug3("%s: cannot handle key", __func__); 1487 goto out; 1488 } 1489 /* register callback for USERAUTH_PK_OK message */ 1490 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1491 1492 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1493 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1494 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1495 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1496 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1497 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1498 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1499 (r = sshpkt_send(ssh)) != 0) 1500 fatal("%s: %s", __func__, ssh_err(r)); 1501 sent = 1; 1502 1503 out: 1504 free(alg); 1505 free(blob); 1506 return sent; 1507 } 1508 1509 static struct sshkey * 1510 load_identity_file(Identity *id) 1511 { 1512 struct sshkey *private = NULL; 1513 char prompt[300], *passphrase, *comment; 1514 int r, quit = 0, i; 1515 struct stat st; 1516 1517 if (stat(id->filename, &st) == -1) { 1518 do_log2(id->userprovided ? 1519 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1520 "no such identity: %s: %s", id->filename, strerror(errno)); 1521 return NULL; 1522 } 1523 snprintf(prompt, sizeof prompt, 1524 "Enter passphrase for key '%.100s': ", id->filename); 1525 for (i = 0; i <= options.number_of_password_prompts; i++) { 1526 if (i == 0) 1527 passphrase = ""; 1528 else { 1529 passphrase = read_passphrase(prompt, 0); 1530 if (*passphrase == '\0') { 1531 debug2("no passphrase given, try next key"); 1532 free(passphrase); 1533 break; 1534 } 1535 } 1536 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1537 passphrase, &private, &comment))) { 1538 case 0: 1539 break; 1540 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1541 if (options.batch_mode) { 1542 quit = 1; 1543 break; 1544 } 1545 if (i != 0) 1546 debug2("bad passphrase given, try again..."); 1547 break; 1548 case SSH_ERR_SYSTEM_ERROR: 1549 if (errno == ENOENT) { 1550 debug2("Load key \"%s\": %s", 1551 id->filename, ssh_err(r)); 1552 quit = 1; 1553 break; 1554 } 1555 /* FALLTHROUGH */ 1556 default: 1557 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1558 quit = 1; 1559 break; 1560 } 1561 if (private != NULL && sshkey_is_sk(private) && 1562 options.sk_provider == NULL) { 1563 debug("key \"%s\" is an authenticator-hosted key, " 1564 "but no provider specified", id->filename); 1565 sshkey_free(private); 1566 private = NULL; 1567 quit = 1; 1568 } 1569 if (!quit && private != NULL && id->agent_fd == -1 && 1570 !(id->key && id->isprivate)) 1571 maybe_add_key_to_agent(id->filename, private, comment, 1572 passphrase); 1573 if (i > 0) 1574 freezero(passphrase, strlen(passphrase)); 1575 free(comment); 1576 if (private != NULL || quit) 1577 break; 1578 } 1579 return private; 1580 } 1581 1582 static int 1583 key_type_allowed_by_config(struct sshkey *key) 1584 { 1585 if (match_pattern_list(sshkey_ssh_name(key), 1586 options.pubkey_key_types, 0) == 1) 1587 return 1; 1588 1589 /* RSA keys/certs might be allowed by alternate signature types */ 1590 switch (key->type) { 1591 case KEY_RSA: 1592 if (match_pattern_list("rsa-sha2-512", 1593 options.pubkey_key_types, 0) == 1) 1594 return 1; 1595 if (match_pattern_list("rsa-sha2-256", 1596 options.pubkey_key_types, 0) == 1) 1597 return 1; 1598 break; 1599 case KEY_RSA_CERT: 1600 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1601 options.pubkey_key_types, 0) == 1) 1602 return 1; 1603 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1604 options.pubkey_key_types, 0) == 1) 1605 return 1; 1606 break; 1607 } 1608 return 0; 1609 } 1610 1611 1612 /* 1613 * try keys in the following order: 1614 * 1. certificates listed in the config file 1615 * 2. other input certificates 1616 * 3. agent keys that are found in the config file 1617 * 4. other agent keys 1618 * 5. keys that are only listed in the config file 1619 */ 1620 static void 1621 pubkey_prepare(Authctxt *authctxt) 1622 { 1623 struct identity *id, *id2, *tmp; 1624 struct idlist agent, files, *preferred; 1625 struct sshkey *key; 1626 int agent_fd = -1, i, r, found; 1627 size_t j; 1628 struct ssh_identitylist *idlist; 1629 char *ident; 1630 1631 TAILQ_INIT(&agent); /* keys from the agent */ 1632 TAILQ_INIT(&files); /* keys from the config file */ 1633 preferred = &authctxt->keys; 1634 TAILQ_INIT(preferred); /* preferred order of keys */ 1635 1636 /* list of keys stored in the filesystem and PKCS#11 */ 1637 for (i = 0; i < options.num_identity_files; i++) { 1638 key = options.identity_keys[i]; 1639 if (key && key->cert && 1640 key->cert->type != SSH2_CERT_TYPE_USER) { 1641 debug("%s: ignoring certificate %s: not a user " 1642 "certificate", __func__, 1643 options.identity_files[i]); 1644 continue; 1645 } 1646 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1647 debug("%s: ignoring authenticator-hosted key %s as no " 1648 "SecurityKeyProvider has been specified", 1649 __func__, options.identity_files[i]); 1650 continue; 1651 } 1652 options.identity_keys[i] = NULL; 1653 id = xcalloc(1, sizeof(*id)); 1654 id->agent_fd = -1; 1655 id->key = key; 1656 id->filename = xstrdup(options.identity_files[i]); 1657 id->userprovided = options.identity_file_userprovided[i]; 1658 TAILQ_INSERT_TAIL(&files, id, next); 1659 } 1660 /* list of certificates specified by user */ 1661 for (i = 0; i < options.num_certificate_files; i++) { 1662 key = options.certificates[i]; 1663 if (!sshkey_is_cert(key) || key->cert == NULL || 1664 key->cert->type != SSH2_CERT_TYPE_USER) { 1665 debug("%s: ignoring certificate %s: not a user " 1666 "certificate", __func__, 1667 options.identity_files[i]); 1668 continue; 1669 } 1670 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1671 debug("%s: ignoring authenticator-hosted key " 1672 "certificate %s as no " 1673 "SecurityKeyProvider has been specified", 1674 __func__, options.identity_files[i]); 1675 continue; 1676 } 1677 id = xcalloc(1, sizeof(*id)); 1678 id->agent_fd = -1; 1679 id->key = key; 1680 id->filename = xstrdup(options.certificate_files[i]); 1681 id->userprovided = options.certificate_file_userprovided[i]; 1682 TAILQ_INSERT_TAIL(preferred, id, next); 1683 } 1684 /* list of keys supported by the agent */ 1685 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1686 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1687 debug("%s: ssh_get_authentication_socket: %s", 1688 __func__, ssh_err(r)); 1689 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1690 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1691 debug("%s: ssh_fetch_identitylist: %s", 1692 __func__, ssh_err(r)); 1693 close(agent_fd); 1694 } else { 1695 for (j = 0; j < idlist->nkeys; j++) { 1696 found = 0; 1697 TAILQ_FOREACH(id, &files, next) { 1698 /* 1699 * agent keys from the config file are 1700 * preferred 1701 */ 1702 if (sshkey_equal(idlist->keys[j], id->key)) { 1703 TAILQ_REMOVE(&files, id, next); 1704 TAILQ_INSERT_TAIL(preferred, id, next); 1705 id->agent_fd = agent_fd; 1706 found = 1; 1707 break; 1708 } 1709 } 1710 if (!found && !options.identities_only) { 1711 id = xcalloc(1, sizeof(*id)); 1712 /* XXX "steals" key/comment from idlist */ 1713 id->key = idlist->keys[j]; 1714 id->filename = idlist->comments[j]; 1715 idlist->keys[j] = NULL; 1716 idlist->comments[j] = NULL; 1717 id->agent_fd = agent_fd; 1718 TAILQ_INSERT_TAIL(&agent, id, next); 1719 } 1720 } 1721 ssh_free_identitylist(idlist); 1722 /* append remaining agent keys */ 1723 TAILQ_CONCAT(preferred, &agent, next); 1724 authctxt->agent_fd = agent_fd; 1725 } 1726 /* Prefer PKCS11 keys that are explicitly listed */ 1727 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1728 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1729 continue; 1730 found = 0; 1731 TAILQ_FOREACH(id2, &files, next) { 1732 if (id2->key == NULL || 1733 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1734 continue; 1735 if (sshkey_equal(id->key, id2->key)) { 1736 TAILQ_REMOVE(&files, id, next); 1737 TAILQ_INSERT_TAIL(preferred, id, next); 1738 found = 1; 1739 break; 1740 } 1741 } 1742 /* If IdentitiesOnly set and key not found then don't use it */ 1743 if (!found && options.identities_only) { 1744 TAILQ_REMOVE(&files, id, next); 1745 freezero(id, sizeof(*id)); 1746 } 1747 } 1748 /* append remaining keys from the config file */ 1749 TAILQ_CONCAT(preferred, &files, next); 1750 /* finally, filter by PubkeyAcceptedKeyTypes */ 1751 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1752 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1753 debug("Skipping %s key %s - " 1754 "not in PubkeyAcceptedKeyTypes", 1755 sshkey_ssh_name(id->key), id->filename); 1756 TAILQ_REMOVE(preferred, id, next); 1757 sshkey_free(id->key); 1758 free(id->filename); 1759 memset(id, 0, sizeof(*id)); 1760 continue; 1761 } 1762 } 1763 /* List the keys we plan on using */ 1764 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1765 ident = format_identity(id); 1766 debug("Will attempt key: %s", ident); 1767 free(ident); 1768 } 1769 debug2("%s: done", __func__); 1770 } 1771 1772 static void 1773 pubkey_cleanup(struct ssh *ssh) 1774 { 1775 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1776 Identity *id; 1777 1778 if (authctxt->agent_fd != -1) { 1779 ssh_close_authentication_socket(authctxt->agent_fd); 1780 authctxt->agent_fd = -1; 1781 } 1782 for (id = TAILQ_FIRST(&authctxt->keys); id; 1783 id = TAILQ_FIRST(&authctxt->keys)) { 1784 TAILQ_REMOVE(&authctxt->keys, id, next); 1785 sshkey_free(id->key); 1786 free(id->filename); 1787 free(id); 1788 } 1789 } 1790 1791 static void 1792 pubkey_reset(Authctxt *authctxt) 1793 { 1794 Identity *id; 1795 1796 TAILQ_FOREACH(id, &authctxt->keys, next) 1797 id->tried = 0; 1798 } 1799 1800 static int 1801 try_identity(Identity *id) 1802 { 1803 if (!id->key) 1804 return (0); 1805 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1806 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1807 debug("Skipped %s key %s for RSA/MD5 server", 1808 sshkey_type(id->key), id->filename); 1809 return (0); 1810 } 1811 return 1; 1812 } 1813 1814 static int 1815 userauth_pubkey(struct ssh *ssh) 1816 { 1817 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1818 Identity *id; 1819 int sent = 0; 1820 char *ident; 1821 1822 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1823 if (id->tried++) 1824 return (0); 1825 /* move key to the end of the queue */ 1826 TAILQ_REMOVE(&authctxt->keys, id, next); 1827 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1828 /* 1829 * send a test message if we have the public key. for 1830 * encrypted keys we cannot do this and have to load the 1831 * private key instead 1832 */ 1833 if (id->key != NULL) { 1834 if (try_identity(id)) { 1835 ident = format_identity(id); 1836 debug("Offering public key: %s", ident); 1837 free(ident); 1838 sent = send_pubkey_test(ssh, id); 1839 } 1840 } else { 1841 debug("Trying private key: %s", id->filename); 1842 id->key = load_identity_file(id); 1843 if (id->key != NULL) { 1844 if (try_identity(id)) { 1845 id->isprivate = 1; 1846 sent = sign_and_send_pubkey(ssh, id); 1847 } 1848 sshkey_free(id->key); 1849 id->key = NULL; 1850 id->isprivate = 0; 1851 } 1852 } 1853 if (sent) 1854 return (sent); 1855 } 1856 return (0); 1857 } 1858 1859 /* 1860 * Send userauth request message specifying keyboard-interactive method. 1861 */ 1862 static int 1863 userauth_kbdint(struct ssh *ssh) 1864 { 1865 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1866 int r; 1867 1868 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1869 return 0; 1870 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1871 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1872 debug3("userauth_kbdint: disable: no info_req_seen"); 1873 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1874 return 0; 1875 } 1876 1877 debug2("userauth_kbdint"); 1878 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1879 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1880 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1881 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1882 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1883 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1884 options.kbd_interactive_devices : "")) != 0 || 1885 (r = sshpkt_send(ssh)) != 0) 1886 fatal("%s: %s", __func__, ssh_err(r)); 1887 1888 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1889 return 1; 1890 } 1891 1892 /* 1893 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1894 */ 1895 static int 1896 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1897 { 1898 Authctxt *authctxt = ssh->authctxt; 1899 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1900 char *response = NULL; 1901 u_char echo = 0; 1902 u_int num_prompts, i; 1903 int r; 1904 1905 debug2("input_userauth_info_req"); 1906 1907 if (authctxt == NULL) 1908 fatal("input_userauth_info_req: no authentication context"); 1909 1910 authctxt->info_req_seen = 1; 1911 1912 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1913 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1914 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1915 goto out; 1916 if (strlen(name) > 0) 1917 logit("%s", name); 1918 if (strlen(inst) > 0) 1919 logit("%s", inst); 1920 1921 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1922 goto out; 1923 /* 1924 * Begin to build info response packet based on prompts requested. 1925 * We commit to providing the correct number of responses, so if 1926 * further on we run into a problem that prevents this, we have to 1927 * be sure and clean this up and send a correct error response. 1928 */ 1929 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1930 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1931 goto out; 1932 1933 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1934 for (i = 0; i < num_prompts; i++) { 1935 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1936 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1937 goto out; 1938 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1939 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1940 goto out; 1941 freezero(response, strlen(response)); 1942 free(prompt); 1943 response = prompt = NULL; 1944 } 1945 /* done with parsing incoming message. */ 1946 if ((r = sshpkt_get_end(ssh)) != 0 || 1947 (r = sshpkt_add_padding(ssh, 64)) != 0) 1948 goto out; 1949 r = sshpkt_send(ssh); 1950 out: 1951 if (response) 1952 freezero(response, strlen(response)); 1953 free(prompt); 1954 free(name); 1955 free(inst); 1956 free(lang); 1957 return r; 1958 } 1959 1960 static int 1961 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1962 const u_char *data, size_t datalen) 1963 { 1964 struct sshbuf *b; 1965 struct stat st; 1966 pid_t pid; 1967 int r, to[2], from[2], status; 1968 int sock = ssh_packet_get_connection_in(ssh); 1969 u_char rversion = 0, version = 2; 1970 void (*osigchld)(int); 1971 1972 *sigp = NULL; 1973 *lenp = 0; 1974 1975 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1976 error("%s: not installed: %s", __func__, strerror(errno)); 1977 return -1; 1978 } 1979 if (fflush(stdout) != 0) { 1980 error("%s: fflush: %s", __func__, strerror(errno)); 1981 return -1; 1982 } 1983 if (pipe(to) == -1) { 1984 error("%s: pipe: %s", __func__, strerror(errno)); 1985 return -1; 1986 } 1987 if (pipe(from) == -1) { 1988 error("%s: pipe: %s", __func__, strerror(errno)); 1989 return -1; 1990 } 1991 if ((pid = fork()) == -1) { 1992 error("%s: fork: %s", __func__, strerror(errno)); 1993 return -1; 1994 } 1995 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1996 if (pid == 0) { 1997 close(from[0]); 1998 if (dup2(from[1], STDOUT_FILENO) == -1) 1999 fatal("%s: dup2: %s", __func__, strerror(errno)); 2000 close(to[1]); 2001 if (dup2(to[0], STDIN_FILENO) == -1) 2002 fatal("%s: dup2: %s", __func__, strerror(errno)); 2003 close(from[1]); 2004 close(to[0]); 2005 2006 if (dup2(sock, STDERR_FILENO + 1) == -1) 2007 fatal("%s: dup2: %s", __func__, strerror(errno)); 2008 sock = STDERR_FILENO + 1; 2009 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2010 closefrom(sock + 1); 2011 2012 debug3("%s: [child] pid=%ld, exec %s", 2013 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 2014 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2015 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 2016 strerror(errno)); 2017 } 2018 close(from[1]); 2019 close(to[0]); 2020 sock = STDERR_FILENO + 1; 2021 2022 if ((b = sshbuf_new()) == NULL) 2023 fatal("%s: sshbuf_new failed", __func__); 2024 /* send # of sock, data to be signed */ 2025 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2026 (r = sshbuf_put_string(b, data, datalen)) != 0) 2027 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 2028 if (ssh_msg_send(to[1], version, b) == -1) 2029 fatal("%s: couldn't send request", __func__); 2030 sshbuf_reset(b); 2031 r = ssh_msg_recv(from[0], b); 2032 close(from[0]); 2033 close(to[1]); 2034 if (r < 0) { 2035 error("%s: no reply", __func__); 2036 goto fail; 2037 } 2038 2039 errno = 0; 2040 while (waitpid(pid, &status, 0) == -1) { 2041 if (errno != EINTR) { 2042 error("%s: waitpid %ld: %s", 2043 __func__, (long)pid, strerror(errno)); 2044 goto fail; 2045 } 2046 } 2047 if (!WIFEXITED(status)) { 2048 error("%s: exited abnormally", __func__); 2049 goto fail; 2050 } 2051 if (WEXITSTATUS(status) != 0) { 2052 error("%s: exited with status %d", 2053 __func__, WEXITSTATUS(status)); 2054 goto fail; 2055 } 2056 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2057 error("%s: buffer error: %s", __func__, ssh_err(r)); 2058 goto fail; 2059 } 2060 if (rversion != version) { 2061 error("%s: bad version", __func__); 2062 goto fail; 2063 } 2064 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2065 error("%s: buffer error: %s", __func__, ssh_err(r)); 2066 fail: 2067 ssh_signal(SIGCHLD, osigchld); 2068 sshbuf_free(b); 2069 return -1; 2070 } 2071 ssh_signal(SIGCHLD, osigchld); 2072 sshbuf_free(b); 2073 2074 return 0; 2075 } 2076 2077 static int 2078 userauth_hostbased(struct ssh *ssh) 2079 { 2080 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2081 struct sshkey *private = NULL; 2082 struct sshbuf *b = NULL; 2083 u_char *sig = NULL, *keyblob = NULL; 2084 char *fp = NULL, *chost = NULL, *lname = NULL; 2085 size_t siglen = 0, keylen = 0; 2086 int i, r, success = 0; 2087 2088 if (authctxt->ktypes == NULL) { 2089 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2090 authctxt->ktypes = authctxt->oktypes; 2091 } 2092 2093 /* 2094 * Work through each listed type pattern in HostbasedKeyTypes, 2095 * trying each hostkey that matches the type in turn. 2096 */ 2097 for (;;) { 2098 if (authctxt->active_ktype == NULL) 2099 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2100 if (authctxt->active_ktype == NULL || 2101 *authctxt->active_ktype == '\0') 2102 break; 2103 debug3("%s: trying key type %s", __func__, 2104 authctxt->active_ktype); 2105 2106 /* check for a useful key */ 2107 private = NULL; 2108 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2109 if (authctxt->sensitive->keys[i] == NULL || 2110 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2111 continue; 2112 if (match_pattern_list( 2113 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2114 authctxt->active_ktype, 0) != 1) 2115 continue; 2116 /* we take and free the key */ 2117 private = authctxt->sensitive->keys[i]; 2118 authctxt->sensitive->keys[i] = NULL; 2119 break; 2120 } 2121 /* Found one */ 2122 if (private != NULL) 2123 break; 2124 /* No more keys of this type; advance */ 2125 authctxt->active_ktype = NULL; 2126 } 2127 if (private == NULL) { 2128 free(authctxt->oktypes); 2129 authctxt->oktypes = authctxt->ktypes = NULL; 2130 authctxt->active_ktype = NULL; 2131 debug("No more client hostkeys for hostbased authentication."); 2132 goto out; 2133 } 2134 2135 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2136 SSH_FP_DEFAULT)) == NULL) { 2137 error("%s: sshkey_fingerprint failed", __func__); 2138 goto out; 2139 } 2140 debug("%s: trying hostkey %s %s", 2141 __func__, sshkey_ssh_name(private), fp); 2142 2143 /* figure out a name for the client host */ 2144 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2145 if (lname == NULL) { 2146 error("%s: cannot get local ipaddr/name", __func__); 2147 goto out; 2148 } 2149 2150 /* XXX sshbuf_put_stringf? */ 2151 xasprintf(&chost, "%s.", lname); 2152 debug2("%s: chost %s", __func__, chost); 2153 2154 /* construct data */ 2155 if ((b = sshbuf_new()) == NULL) { 2156 error("%s: sshbuf_new failed", __func__); 2157 goto out; 2158 } 2159 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2160 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2161 goto out; 2162 } 2163 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2164 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2165 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2166 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2167 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2168 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2169 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2170 (r = sshbuf_put_cstring(b, chost)) != 0 || 2171 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2172 error("%s: buffer error: %s", __func__, ssh_err(r)); 2173 goto out; 2174 } 2175 2176 #ifdef DEBUG_PK 2177 sshbuf_dump(b, stderr); 2178 #endif 2179 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2180 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2181 error("sign using hostkey %s %s failed", 2182 sshkey_ssh_name(private), fp); 2183 goto out; 2184 } 2185 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2186 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2187 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2188 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2189 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2190 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2191 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2192 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2193 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2194 (r = sshpkt_send(ssh)) != 0) { 2195 error("%s: packet error: %s", __func__, ssh_err(r)); 2196 goto out; 2197 } 2198 success = 1; 2199 2200 out: 2201 if (sig != NULL) 2202 freezero(sig, siglen); 2203 free(keyblob); 2204 free(lname); 2205 free(fp); 2206 free(chost); 2207 sshkey_free(private); 2208 sshbuf_free(b); 2209 2210 return success; 2211 } 2212 2213 /* find auth method */ 2214 2215 /* 2216 * given auth method name, if configurable options permit this method fill 2217 * in auth_ident field and return true, otherwise return false. 2218 */ 2219 static int 2220 authmethod_is_enabled(Authmethod *method) 2221 { 2222 if (method == NULL) 2223 return 0; 2224 /* return false if options indicate this method is disabled */ 2225 if (method->enabled == NULL || *method->enabled == 0) 2226 return 0; 2227 /* return false if batch mode is enabled but method needs interactive mode */ 2228 if (method->batch_flag != NULL && *method->batch_flag != 0) 2229 return 0; 2230 return 1; 2231 } 2232 2233 static Authmethod * 2234 authmethod_lookup(const char *name) 2235 { 2236 Authmethod *method = NULL; 2237 if (name != NULL) 2238 for (method = authmethods; method->name != NULL; method++) 2239 if (strcmp(name, method->name) == 0) 2240 return method; 2241 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2242 return NULL; 2243 } 2244 2245 /* XXX internal state */ 2246 static Authmethod *current = NULL; 2247 static char *supported = NULL; 2248 static char *preferred = NULL; 2249 2250 /* 2251 * Given the authentication method list sent by the server, return the 2252 * next method we should try. If the server initially sends a nil list, 2253 * use a built-in default list. 2254 */ 2255 static Authmethod * 2256 authmethod_get(char *authlist) 2257 { 2258 char *name = NULL; 2259 u_int next; 2260 2261 /* Use a suitable default if we're passed a nil list. */ 2262 if (authlist == NULL || strlen(authlist) == 0) 2263 authlist = options.preferred_authentications; 2264 2265 if (supported == NULL || strcmp(authlist, supported) != 0) { 2266 debug3("start over, passed a different list %s", authlist); 2267 free(supported); 2268 supported = xstrdup(authlist); 2269 preferred = options.preferred_authentications; 2270 debug3("preferred %s", preferred); 2271 current = NULL; 2272 } else if (current != NULL && authmethod_is_enabled(current)) 2273 return current; 2274 2275 for (;;) { 2276 if ((name = match_list(preferred, supported, &next)) == NULL) { 2277 debug("No more authentication methods to try."); 2278 current = NULL; 2279 return NULL; 2280 } 2281 preferred += next; 2282 debug3("authmethod_lookup %s", name); 2283 debug3("remaining preferred: %s", preferred); 2284 if ((current = authmethod_lookup(name)) != NULL && 2285 authmethod_is_enabled(current)) { 2286 debug3("authmethod_is_enabled %s", name); 2287 debug("Next authentication method: %s", name); 2288 free(name); 2289 return current; 2290 } 2291 free(name); 2292 } 2293 } 2294 2295 static char * 2296 authmethods_get(void) 2297 { 2298 Authmethod *method = NULL; 2299 struct sshbuf *b; 2300 char *list; 2301 int r; 2302 2303 if ((b = sshbuf_new()) == NULL) 2304 fatal("%s: sshbuf_new failed", __func__); 2305 for (method = authmethods; method->name != NULL; method++) { 2306 if (authmethod_is_enabled(method)) { 2307 if ((r = sshbuf_putf(b, "%s%s", 2308 sshbuf_len(b) ? "," : "", method->name)) != 0) 2309 fatal("%s: buffer error: %s", 2310 __func__, ssh_err(r)); 2311 } 2312 } 2313 if ((list = sshbuf_dup_string(b)) == NULL) 2314 fatal("%s: sshbuf_dup_string failed", __func__); 2315 sshbuf_free(b); 2316 return list; 2317 } 2318