1 /* $OpenBSD: sshconnect2.c,v 1.339 2020/12/22 00:15:23 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 <limits.h> 37 #include <netdb.h> 38 #include <pwd.h> 39 #include <signal.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <stdarg.h> 43 #include <unistd.h> 44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 45 #include <vis.h> 46 #endif 47 48 #include "openbsd-compat/sys-queue.h" 49 50 #include "xmalloc.h" 51 #include "ssh.h" 52 #include "ssh2.h" 53 #include "sshbuf.h" 54 #include "packet.h" 55 #include "compat.h" 56 #include "cipher.h" 57 #include "sshkey.h" 58 #include "kex.h" 59 #include "myproposal.h" 60 #include "sshconnect.h" 61 #include "authfile.h" 62 #include "dh.h" 63 #include "authfd.h" 64 #include "log.h" 65 #include "misc.h" 66 #include "readconf.h" 67 #include "match.h" 68 #include "dispatch.h" 69 #include "canohost.h" 70 #include "msg.h" 71 #include "pathnames.h" 72 #include "uidswap.h" 73 #include "hostfile.h" 74 #include "ssherr.h" 75 #include "utf8.h" 76 #include "ssh-sk.h" 77 #include "sk-api.h" 78 79 #ifdef GSSAPI 80 #include "ssh-gss.h" 81 #endif 82 83 /* import */ 84 extern char *client_version_string; 85 extern char *server_version_string; 86 extern Options options; 87 88 /* 89 * SSH2 key exchange 90 */ 91 92 u_char *session_id2 = NULL; 93 u_int session_id2_len = 0; 94 95 static char *xxx_host; 96 static struct sockaddr *xxx_hostaddr; 97 static const struct ssh_conn_info *xxx_conn_info; 98 99 static int 100 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 101 { 102 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 103 xxx_conn_info) == -1) 104 fatal("Host key verification failed."); 105 return 0; 106 } 107 108 /* Returns the first item from a comma-separated algorithm list */ 109 static char * 110 first_alg(const char *algs) 111 { 112 char *ret, *cp; 113 114 ret = xstrdup(algs); 115 if ((cp = strchr(ret, ',')) != NULL) 116 *cp = '\0'; 117 return ret; 118 } 119 120 static char * 121 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 122 const struct ssh_conn_info *cinfo) 123 { 124 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 125 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 126 size_t maxlen; 127 struct hostkeys *hostkeys = NULL; 128 int ktype; 129 u_int i; 130 131 /* Find all hostkeys for this hostname */ 132 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 133 hostkeys = init_hostkeys(); 134 for (i = 0; i < options.num_user_hostfiles; i++) 135 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 136 for (i = 0; i < options.num_system_hostfiles; i++) { 137 load_hostkeys(hostkeys, hostname, 138 options.system_hostfiles[i], 0); 139 } 140 if (options.known_hosts_command != NULL) { 141 load_hostkeys_command(hostkeys, options.known_hosts_command, 142 "ORDER", cinfo, NULL, host); 143 } 144 /* 145 * If a plain public key exists that matches the type of the best 146 * preference HostkeyAlgorithms, then use the whole list as is. 147 * Note that we ignore whether the best preference algorithm is a 148 * certificate type, as sshconnect.c will downgrade certs to 149 * plain keys if necessary. 150 */ 151 best = first_alg(options.hostkeyalgorithms); 152 if (lookup_key_in_hostkeys_by_type(hostkeys, 153 sshkey_type_plain(sshkey_type_from_name(best)), 154 sshkey_ecdsa_nid_from_name(best), NULL)) { 155 debug3_f("have matching best-preference key type %s, " 156 "using HostkeyAlgorithms verbatim", best); 157 ret = xstrdup(options.hostkeyalgorithms); 158 goto out; 159 } 160 161 /* 162 * Otherwise, prefer the host key algorithms that match known keys 163 * while keeping the ordering of HostkeyAlgorithms as much as possible. 164 */ 165 oavail = avail = xstrdup(options.hostkeyalgorithms); 166 maxlen = strlen(avail) + 1; 167 first = xmalloc(maxlen); 168 last = xmalloc(maxlen); 169 *first = *last = '\0'; 170 171 #define ALG_APPEND(to, from) \ 172 do { \ 173 if (*to != '\0') \ 174 strlcat(to, ",", maxlen); \ 175 strlcat(to, from, maxlen); \ 176 } while (0) 177 178 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 179 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 180 fatal_f("unknown alg %s", alg); 181 /* 182 * If we have a @cert-authority marker in known_hosts then 183 * prefer all certificate algorithms. 184 */ 185 if (sshkey_type_is_cert(ktype) && 186 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 187 ALG_APPEND(first, alg); 188 continue; 189 } 190 /* If the key appears in known_hosts then prefer it */ 191 if (lookup_key_in_hostkeys_by_type(hostkeys, 192 sshkey_type_plain(ktype), 193 sshkey_ecdsa_nid_from_name(alg), NULL)) { 194 ALG_APPEND(first, alg); 195 continue; 196 } 197 /* Otherwise, put it last */ 198 ALG_APPEND(last, alg); 199 } 200 #undef ALG_APPEND 201 xasprintf(&ret, "%s%s%s", first, 202 (*first == '\0' || *last == '\0') ? "" : ",", last); 203 if (*first != '\0') 204 debug3_f("prefer hostkeyalgs: %s", first); 205 else 206 debug3_f("no algorithms matched; accept original"); 207 out: 208 free(best); 209 free(first); 210 free(last); 211 free(hostname); 212 free(oavail); 213 free_hostkeys(hostkeys); 214 215 return ret; 216 } 217 218 void 219 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 220 const struct ssh_conn_info *cinfo) 221 { 222 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 223 char *s, *all_key; 224 int r, use_known_hosts_order = 0; 225 226 xxx_host = host; 227 xxx_hostaddr = hostaddr; 228 xxx_conn_info = cinfo; 229 230 /* 231 * If the user has not specified HostkeyAlgorithms, or has only 232 * appended or removed algorithms from that list then prefer algorithms 233 * that are in the list that are supported by known_hosts keys. 234 */ 235 if (options.hostkeyalgorithms == NULL || 236 options.hostkeyalgorithms[0] == '-' || 237 options.hostkeyalgorithms[0] == '+') 238 use_known_hosts_order = 1; 239 240 /* Expand or fill in HostkeyAlgorithms */ 241 all_key = sshkey_alg_list(0, 0, 1, ','); 242 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 243 kex_default_pk_alg(), all_key)) != 0) 244 fatal_fr(r, "kex_assemble_namelist"); 245 free(all_key); 246 247 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 248 fatal_f("kex_names_cat"); 249 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 250 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 251 compat_cipher_proposal(options.ciphers); 252 myproposal[PROPOSAL_ENC_ALGS_STOC] = 253 compat_cipher_proposal(options.ciphers); 254 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 255 myproposal[PROPOSAL_COMP_ALGS_STOC] = 256 (char *)compression_alg_list(options.compression); 257 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 258 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 259 if (use_known_hosts_order) { 260 /* Query known_hosts and prefer algorithms that appear there */ 261 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 262 compat_pkalg_proposal( 263 order_hostkeyalgs(host, hostaddr, port, cinfo)); 264 } else { 265 /* Use specified HostkeyAlgorithms exactly */ 266 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 267 compat_pkalg_proposal(options.hostkeyalgorithms); 268 } 269 270 if (options.rekey_limit || options.rekey_interval) 271 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 272 options.rekey_interval); 273 274 /* start key exchange */ 275 if ((r = kex_setup(ssh, myproposal)) != 0) 276 fatal_r(r, "kex_setup"); 277 #ifdef WITH_OPENSSL 278 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 279 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 280 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 281 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 282 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 283 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 284 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 285 # ifdef OPENSSL_HAS_ECC 286 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 287 # endif 288 #endif 289 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 290 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 291 ssh->kex->verify_host_key=&verify_host_key_callback; 292 293 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 294 295 /* remove ext-info from the KEX proposals for rekeying */ 296 myproposal[PROPOSAL_KEX_ALGS] = 297 compat_kex_proposal(options.kex_algorithms); 298 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 299 fatal_r(r, "kex_prop2buf"); 300 301 session_id2 = ssh->kex->session_id; 302 session_id2_len = ssh->kex->session_id_len; 303 304 #ifdef DEBUG_KEXDH 305 /* send 1st encrypted/maced/compressed message */ 306 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 307 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 308 (r = sshpkt_send(ssh)) != 0 || 309 (r = ssh_packet_write_wait(ssh)) != 0) 310 fatal_fr(r, "send packet"); 311 #endif 312 } 313 314 /* 315 * Authenticate user 316 */ 317 318 typedef struct cauthctxt Authctxt; 319 typedef struct cauthmethod Authmethod; 320 typedef struct identity Identity; 321 typedef struct idlist Idlist; 322 323 struct identity { 324 TAILQ_ENTRY(identity) next; 325 int agent_fd; /* >=0 if agent supports key */ 326 struct sshkey *key; /* public/private key */ 327 char *filename; /* comment for agent-only keys */ 328 int tried; 329 int isprivate; /* key points to the private key */ 330 int userprovided; 331 }; 332 TAILQ_HEAD(idlist, identity); 333 334 struct cauthctxt { 335 const char *server_user; 336 const char *local_user; 337 const char *host; 338 const char *service; 339 struct cauthmethod *method; 340 sig_atomic_t success; 341 char *authlist; 342 #ifdef GSSAPI 343 /* gssapi */ 344 gss_OID_set gss_supported_mechs; 345 u_int mech_tried; 346 #endif 347 /* pubkey */ 348 struct idlist keys; 349 int agent_fd; 350 /* hostbased */ 351 Sensitive *sensitive; 352 char *oktypes, *ktypes; 353 const char *active_ktype; 354 /* kbd-interactive */ 355 int info_req_seen; 356 int attempt_kbdint; 357 /* password */ 358 int attempt_passwd; 359 /* generic */ 360 void *methoddata; 361 }; 362 363 struct cauthmethod { 364 char *name; /* string to compare against server's list */ 365 int (*userauth)(struct ssh *ssh); 366 void (*cleanup)(struct ssh *ssh); 367 int *enabled; /* flag in option struct that enables method */ 368 int *batch_flag; /* flag in option struct that disables method */ 369 }; 370 371 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 372 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 373 static int input_userauth_success(int, u_int32_t, struct ssh *); 374 static int input_userauth_failure(int, u_int32_t, struct ssh *); 375 static int input_userauth_banner(int, u_int32_t, struct ssh *); 376 static int input_userauth_error(int, u_int32_t, struct ssh *); 377 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 378 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 379 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 380 381 static int userauth_none(struct ssh *); 382 static int userauth_pubkey(struct ssh *); 383 static int userauth_passwd(struct ssh *); 384 static int userauth_kbdint(struct ssh *); 385 static int userauth_hostbased(struct ssh *); 386 387 #ifdef GSSAPI 388 static int userauth_gssapi(struct ssh *); 389 static void userauth_gssapi_cleanup(struct ssh *); 390 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 391 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 392 static int input_gssapi_error(int, u_int32_t, struct ssh *); 393 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 394 #endif 395 396 void userauth(struct ssh *, char *); 397 398 static void pubkey_cleanup(struct ssh *); 399 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 400 static void pubkey_prepare(Authctxt *); 401 static void pubkey_reset(Authctxt *); 402 static struct sshkey *load_identity_file(Identity *); 403 404 static Authmethod *authmethod_get(char *authlist); 405 static Authmethod *authmethod_lookup(const char *name); 406 static char *authmethods_get(void); 407 408 Authmethod authmethods[] = { 409 #ifdef GSSAPI 410 {"gssapi-with-mic", 411 userauth_gssapi, 412 userauth_gssapi_cleanup, 413 &options.gss_authentication, 414 NULL}, 415 #endif 416 {"hostbased", 417 userauth_hostbased, 418 NULL, 419 &options.hostbased_authentication, 420 NULL}, 421 {"publickey", 422 userauth_pubkey, 423 NULL, 424 &options.pubkey_authentication, 425 NULL}, 426 {"keyboard-interactive", 427 userauth_kbdint, 428 NULL, 429 &options.kbd_interactive_authentication, 430 &options.batch_mode}, 431 {"password", 432 userauth_passwd, 433 NULL, 434 &options.password_authentication, 435 &options.batch_mode}, 436 {"none", 437 userauth_none, 438 NULL, 439 NULL, 440 NULL}, 441 {NULL, NULL, NULL, NULL, NULL} 442 }; 443 444 void 445 ssh_userauth2(struct ssh *ssh, const char *local_user, 446 const char *server_user, char *host, Sensitive *sensitive) 447 { 448 Authctxt authctxt; 449 int r; 450 451 if (options.challenge_response_authentication) 452 options.kbd_interactive_authentication = 1; 453 if (options.preferred_authentications == NULL) 454 options.preferred_authentications = authmethods_get(); 455 456 /* setup authentication context */ 457 memset(&authctxt, 0, sizeof(authctxt)); 458 authctxt.server_user = server_user; 459 authctxt.local_user = local_user; 460 authctxt.host = host; 461 authctxt.service = "ssh-connection"; /* service name */ 462 authctxt.success = 0; 463 authctxt.method = authmethod_lookup("none"); 464 authctxt.authlist = NULL; 465 authctxt.methoddata = NULL; 466 authctxt.sensitive = sensitive; 467 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 468 authctxt.info_req_seen = 0; 469 authctxt.attempt_kbdint = 0; 470 authctxt.attempt_passwd = 0; 471 #if GSSAPI 472 authctxt.gss_supported_mechs = NULL; 473 authctxt.mech_tried = 0; 474 #endif 475 authctxt.agent_fd = -1; 476 pubkey_prepare(&authctxt); 477 if (authctxt.method == NULL) { 478 fatal_f("internal error: cannot send userauth none request"); 479 } 480 481 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 482 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 483 (r = sshpkt_send(ssh)) != 0) 484 fatal_fr(r, "send packet"); 485 486 ssh->authctxt = &authctxt; 487 ssh_dispatch_init(ssh, &input_userauth_error); 488 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 489 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 490 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 491 pubkey_cleanup(ssh); 492 ssh->authctxt = NULL; 493 494 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 495 496 if (!authctxt.success) 497 fatal("Authentication failed."); 498 debug("Authentication succeeded (%s).", authctxt.method->name); 499 } 500 501 /* ARGSUSED */ 502 static int 503 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 504 { 505 int r; 506 507 if (ssh_packet_remaining(ssh) > 0) { 508 char *reply; 509 510 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 511 goto out; 512 debug2("service_accept: %s", reply); 513 free(reply); 514 } else { 515 debug2("buggy server: service_accept w/o service"); 516 } 517 if ((r = sshpkt_get_end(ssh)) != 0) 518 goto out; 519 debug("SSH2_MSG_SERVICE_ACCEPT received"); 520 521 /* initial userauth request */ 522 userauth_none(ssh); 523 524 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 525 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 526 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 527 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 528 r = 0; 529 out: 530 return r; 531 } 532 533 /* ARGSUSED */ 534 static int 535 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 536 { 537 return kex_input_ext_info(type, seqnr, ssh); 538 } 539 540 void 541 userauth(struct ssh *ssh, char *authlist) 542 { 543 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 544 545 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 546 authctxt->method->cleanup(ssh); 547 548 free(authctxt->methoddata); 549 authctxt->methoddata = NULL; 550 if (authlist == NULL) { 551 authlist = authctxt->authlist; 552 } else { 553 free(authctxt->authlist); 554 authctxt->authlist = authlist; 555 } 556 for (;;) { 557 Authmethod *method = authmethod_get(authlist); 558 if (method == NULL) 559 fatal("%s@%s: Permission denied (%s).", 560 authctxt->server_user, authctxt->host, authlist); 561 authctxt->method = method; 562 563 /* reset the per method handler */ 564 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 565 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 566 567 /* and try new method */ 568 if (method->userauth(ssh) != 0) { 569 debug2("we sent a %s packet, wait for reply", method->name); 570 break; 571 } else { 572 debug2("we did not send a packet, disable method"); 573 method->enabled = NULL; 574 } 575 } 576 } 577 578 /* ARGSUSED */ 579 static int 580 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 581 { 582 fatal_f("bad message during authentication: type %d", type); 583 return 0; 584 } 585 586 /* ARGSUSED */ 587 static int 588 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 589 { 590 char *msg = NULL; 591 size_t len; 592 int r; 593 594 debug3_f("entering"); 595 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 596 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 597 goto out; 598 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 599 fmprintf(stderr, "%s", msg); 600 r = 0; 601 out: 602 free(msg); 603 return r; 604 } 605 606 /* ARGSUSED */ 607 static int 608 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 609 { 610 Authctxt *authctxt = ssh->authctxt; 611 612 if (authctxt == NULL) 613 fatal_f("no authentication context"); 614 free(authctxt->authlist); 615 authctxt->authlist = NULL; 616 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 617 authctxt->method->cleanup(ssh); 618 free(authctxt->methoddata); 619 authctxt->methoddata = NULL; 620 authctxt->success = 1; /* break out */ 621 return 0; 622 } 623 624 #if 0 625 static int 626 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 627 { 628 Authctxt *authctxt = ssh->authctxt; 629 630 if (authctxt == NULL) 631 fatal_f("no authentication context"); 632 633 fatal("Unexpected authentication success during %s.", 634 authctxt->method->name); 635 return 0; 636 } 637 #endif 638 639 /* ARGSUSED */ 640 static int 641 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 642 { 643 Authctxt *authctxt = ssh->authctxt; 644 char *authlist = NULL; 645 u_char partial; 646 647 if (authctxt == NULL) 648 fatal("input_userauth_failure: no authentication context"); 649 650 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 651 sshpkt_get_u8(ssh, &partial) != 0 || 652 sshpkt_get_end(ssh) != 0) 653 goto out; 654 655 if (partial != 0) { 656 verbose("Authenticated with partial success."); 657 /* reset state */ 658 pubkey_reset(authctxt); 659 } 660 debug("Authentications that can continue: %s", authlist); 661 662 userauth(ssh, authlist); 663 authlist = NULL; 664 out: 665 free(authlist); 666 return 0; 667 } 668 669 /* 670 * Format an identity for logging including filename, key type, fingerprint 671 * and location (agent, etc.). Caller must free. 672 */ 673 static char * 674 format_identity(Identity *id) 675 { 676 char *fp = NULL, *ret = NULL; 677 const char *note = ""; 678 679 if (id->key != NULL) { 680 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 681 SSH_FP_DEFAULT); 682 } 683 if (id->key) { 684 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 685 note = " token"; 686 else if (sshkey_is_sk(id->key)) 687 note = " authenticator"; 688 } 689 xasprintf(&ret, "%s %s%s%s%s%s%s", 690 id->filename, 691 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 692 fp ? fp : "", 693 id->userprovided ? " explicit" : "", note, 694 id->agent_fd != -1 ? " agent" : ""); 695 free(fp); 696 return ret; 697 } 698 699 /* ARGSUSED */ 700 static int 701 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 702 { 703 Authctxt *authctxt = ssh->authctxt; 704 struct sshkey *key = NULL; 705 Identity *id = NULL; 706 int pktype, found = 0, sent = 0; 707 size_t blen; 708 char *pkalg = NULL, *fp = NULL, *ident = NULL; 709 u_char *pkblob = NULL; 710 int r; 711 712 if (authctxt == NULL) 713 fatal("input_userauth_pk_ok: no authentication context"); 714 715 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 716 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 717 (r = sshpkt_get_end(ssh)) != 0) 718 goto done; 719 720 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 721 debug_f("server sent unknown pkalg %s", pkalg); 722 goto done; 723 } 724 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 725 debug_r(r, "no key from blob. pkalg %s", pkalg); 726 goto done; 727 } 728 if (key->type != pktype) { 729 error("input_userauth_pk_ok: type mismatch " 730 "for decoded key (received %d, expected %d)", 731 key->type, pktype); 732 goto done; 733 } 734 735 /* 736 * search keys in the reverse order, because last candidate has been 737 * moved to the end of the queue. this also avoids confusion by 738 * duplicate keys 739 */ 740 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 741 if (sshkey_equal(key, id->key)) { 742 found = 1; 743 break; 744 } 745 } 746 if (!found || id == NULL) { 747 fp = sshkey_fingerprint(key, options.fingerprint_hash, 748 SSH_FP_DEFAULT); 749 error_f("server replied with unknown key: %s %s", 750 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 751 goto done; 752 } 753 ident = format_identity(id); 754 debug("Server accepts key: %s", ident); 755 sent = sign_and_send_pubkey(ssh, id); 756 r = 0; 757 done: 758 sshkey_free(key); 759 free(ident); 760 free(fp); 761 free(pkalg); 762 free(pkblob); 763 764 /* try another method if we did not send a packet */ 765 if (r == 0 && sent == 0) 766 userauth(ssh, NULL); 767 return r; 768 } 769 770 #ifdef GSSAPI 771 static int 772 userauth_gssapi(struct ssh *ssh) 773 { 774 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 775 Gssctxt *gssctxt = NULL; 776 OM_uint32 min; 777 int r, ok = 0; 778 gss_OID mech = NULL; 779 780 /* Try one GSSAPI method at a time, rather than sending them all at 781 * once. */ 782 783 if (authctxt->gss_supported_mechs == NULL) 784 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 785 786 /* Check to see whether the mechanism is usable before we offer it */ 787 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 788 !ok) { 789 mech = &authctxt->gss_supported_mechs-> 790 elements[authctxt->mech_tried]; 791 /* My DER encoding requires length<128 */ 792 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 793 mech, authctxt->host)) { 794 ok = 1; /* Mechanism works */ 795 } else { 796 authctxt->mech_tried++; 797 } 798 } 799 800 if (!ok || mech == NULL) 801 return 0; 802 803 authctxt->methoddata=(void *)gssctxt; 804 805 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 806 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 807 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 808 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 809 (r = sshpkt_put_u32(ssh, 1)) != 0 || 810 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 811 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 812 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 813 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 814 (r = sshpkt_send(ssh)) != 0) 815 fatal_fr(r, "send packet"); 816 817 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 818 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 819 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 820 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 821 822 authctxt->mech_tried++; /* Move along to next candidate */ 823 824 return 1; 825 } 826 827 static void 828 userauth_gssapi_cleanup(struct ssh *ssh) 829 { 830 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 831 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 832 833 ssh_gssapi_delete_ctx(&gssctxt); 834 authctxt->methoddata = NULL; 835 836 free(authctxt->gss_supported_mechs); 837 authctxt->gss_supported_mechs = NULL; 838 } 839 840 static OM_uint32 841 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 842 { 843 Authctxt *authctxt = ssh->authctxt; 844 Gssctxt *gssctxt = authctxt->methoddata; 845 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 846 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 847 gss_buffer_desc gssbuf; 848 OM_uint32 status, ms, flags; 849 int r; 850 851 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 852 recv_tok, &send_tok, &flags); 853 854 if (send_tok.length > 0) { 855 u_char type = GSS_ERROR(status) ? 856 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 857 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 858 859 if ((r = sshpkt_start(ssh, type)) != 0 || 860 (r = sshpkt_put_string(ssh, send_tok.value, 861 send_tok.length)) != 0 || 862 (r = sshpkt_send(ssh)) != 0) 863 fatal_fr(r, "send %u packet", type); 864 865 gss_release_buffer(&ms, &send_tok); 866 } 867 868 if (status == GSS_S_COMPLETE) { 869 /* send either complete or MIC, depending on mechanism */ 870 if (!(flags & GSS_C_INTEG_FLAG)) { 871 if ((r = sshpkt_start(ssh, 872 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 873 (r = sshpkt_send(ssh)) != 0) 874 fatal_fr(r, "send completion"); 875 } else { 876 struct sshbuf *b; 877 878 if ((b = sshbuf_new()) == NULL) 879 fatal_f("sshbuf_new failed"); 880 ssh_gssapi_buildmic(b, authctxt->server_user, 881 authctxt->service, "gssapi-with-mic"); 882 883 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 884 fatal_f("sshbuf_mutable_ptr failed"); 885 gssbuf.length = sshbuf_len(b); 886 887 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 888 889 if (!GSS_ERROR(status)) { 890 if ((r = sshpkt_start(ssh, 891 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 892 (r = sshpkt_put_string(ssh, mic.value, 893 mic.length)) != 0 || 894 (r = sshpkt_send(ssh)) != 0) 895 fatal_fr(r, "send MIC"); 896 } 897 898 sshbuf_free(b); 899 gss_release_buffer(&ms, &mic); 900 } 901 } 902 903 return status; 904 } 905 906 /* ARGSUSED */ 907 static int 908 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 909 { 910 Authctxt *authctxt = ssh->authctxt; 911 Gssctxt *gssctxt; 912 size_t oidlen; 913 u_char *oidv = NULL; 914 int r; 915 916 if (authctxt == NULL) 917 fatal("input_gssapi_response: no authentication context"); 918 gssctxt = authctxt->methoddata; 919 920 /* Setup our OID */ 921 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 922 goto done; 923 924 if (oidlen <= 2 || 925 oidv[0] != SSH_GSS_OIDTYPE || 926 oidv[1] != oidlen - 2) { 927 debug("Badly encoded mechanism OID received"); 928 userauth(ssh, NULL); 929 goto ok; 930 } 931 932 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 933 fatal("Server returned different OID than expected"); 934 935 if ((r = sshpkt_get_end(ssh)) != 0) 936 goto done; 937 938 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 939 /* Start again with next method on list */ 940 debug("Trying to start again"); 941 userauth(ssh, NULL); 942 goto ok; 943 } 944 ok: 945 r = 0; 946 done: 947 free(oidv); 948 return r; 949 } 950 951 /* ARGSUSED */ 952 static int 953 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 954 { 955 Authctxt *authctxt = ssh->authctxt; 956 gss_buffer_desc recv_tok; 957 u_char *p = NULL; 958 size_t len; 959 OM_uint32 status; 960 int r; 961 962 if (authctxt == NULL) 963 fatal("input_gssapi_response: no authentication context"); 964 965 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 966 (r = sshpkt_get_end(ssh)) != 0) 967 goto out; 968 969 recv_tok.value = p; 970 recv_tok.length = len; 971 status = process_gssapi_token(ssh, &recv_tok); 972 973 /* Start again with the next method in the list */ 974 if (GSS_ERROR(status)) { 975 userauth(ssh, NULL); 976 /* ok */ 977 } 978 r = 0; 979 out: 980 free(p); 981 return r; 982 } 983 984 /* ARGSUSED */ 985 static int 986 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 987 { 988 Authctxt *authctxt = ssh->authctxt; 989 Gssctxt *gssctxt; 990 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 991 gss_buffer_desc recv_tok; 992 OM_uint32 ms; 993 u_char *p = NULL; 994 size_t len; 995 int r; 996 997 if (authctxt == NULL) 998 fatal("input_gssapi_response: no authentication context"); 999 gssctxt = authctxt->methoddata; 1000 1001 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1002 (r = sshpkt_get_end(ssh)) != 0) { 1003 free(p); 1004 return r; 1005 } 1006 1007 /* Stick it into GSSAPI and see what it says */ 1008 recv_tok.value = p; 1009 recv_tok.length = len; 1010 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1011 &recv_tok, &send_tok, NULL); 1012 free(p); 1013 gss_release_buffer(&ms, &send_tok); 1014 1015 /* Server will be returning a failed packet after this one */ 1016 return 0; 1017 } 1018 1019 /* ARGSUSED */ 1020 static int 1021 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1022 { 1023 char *msg = NULL; 1024 char *lang = NULL; 1025 int r; 1026 1027 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1028 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1029 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1030 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1031 goto out; 1032 r = sshpkt_get_end(ssh); 1033 debug("Server GSSAPI Error:\n%s", msg); 1034 out: 1035 free(msg); 1036 free(lang); 1037 return r; 1038 } 1039 #endif /* GSSAPI */ 1040 1041 static int 1042 userauth_none(struct ssh *ssh) 1043 { 1044 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1045 int r; 1046 1047 /* initial userauth request */ 1048 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1049 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1050 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1051 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1052 (r = sshpkt_send(ssh)) != 0) 1053 fatal_fr(r, "send packet"); 1054 return 1; 1055 } 1056 1057 static int 1058 userauth_passwd(struct ssh *ssh) 1059 { 1060 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1061 char *password, *prompt = NULL; 1062 const char *host = options.host_key_alias ? options.host_key_alias : 1063 authctxt->host; 1064 int r; 1065 1066 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1067 return 0; 1068 1069 if (authctxt->attempt_passwd != 1) 1070 error("Permission denied, please try again."); 1071 1072 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1073 password = read_passphrase(prompt, 0); 1074 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1075 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1076 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1077 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1078 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1079 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1080 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1081 (r = sshpkt_send(ssh)) != 0) 1082 fatal_fr(r, "send packet"); 1083 1084 free(prompt); 1085 if (password != NULL) 1086 freezero(password, strlen(password)); 1087 1088 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1089 &input_userauth_passwd_changereq); 1090 1091 return 1; 1092 } 1093 1094 /* 1095 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1096 */ 1097 /* ARGSUSED */ 1098 static int 1099 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1100 { 1101 Authctxt *authctxt = ssh->authctxt; 1102 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1103 char prompt[256]; 1104 const char *host; 1105 int r; 1106 1107 debug2("input_userauth_passwd_changereq"); 1108 1109 if (authctxt == NULL) 1110 fatal("input_userauth_passwd_changereq: " 1111 "no authentication context"); 1112 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1113 1114 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1115 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1116 goto out; 1117 if (strlen(info) > 0) 1118 logit("%s", info); 1119 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1120 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1121 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1122 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1123 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1124 goto out; 1125 1126 snprintf(prompt, sizeof(prompt), 1127 "Enter %.30s@%.128s's old password: ", 1128 authctxt->server_user, host); 1129 password = read_passphrase(prompt, 0); 1130 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1131 goto out; 1132 1133 freezero(password, strlen(password)); 1134 password = NULL; 1135 while (password == NULL) { 1136 snprintf(prompt, sizeof(prompt), 1137 "Enter %.30s@%.128s's new password: ", 1138 authctxt->server_user, host); 1139 password = read_passphrase(prompt, RP_ALLOW_EOF); 1140 if (password == NULL) { 1141 /* bail out */ 1142 r = 0; 1143 goto out; 1144 } 1145 snprintf(prompt, sizeof(prompt), 1146 "Retype %.30s@%.128s's new password: ", 1147 authctxt->server_user, host); 1148 retype = read_passphrase(prompt, 0); 1149 if (strcmp(password, retype) != 0) { 1150 freezero(password, strlen(password)); 1151 logit("Mismatch; try again, EOF to quit."); 1152 password = NULL; 1153 } 1154 freezero(retype, strlen(retype)); 1155 } 1156 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1157 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1158 (r = sshpkt_send(ssh)) != 0) 1159 goto out; 1160 1161 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1162 &input_userauth_passwd_changereq); 1163 r = 0; 1164 out: 1165 if (password) 1166 freezero(password, strlen(password)); 1167 free(info); 1168 free(lang); 1169 return r; 1170 } 1171 1172 /* 1173 * Select an algorithm for publickey signatures. 1174 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1175 * 1176 * Call with ssh==NULL to ignore server-sig-algs extension list and 1177 * only attempt with the key's base signature type. 1178 */ 1179 static char * 1180 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1181 { 1182 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1183 1184 /* 1185 * The signature algorithm will only differ from the key algorithm 1186 * for RSA keys/certs and when the server advertises support for 1187 * newer (SHA2) algorithms. 1188 */ 1189 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1190 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1191 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1192 /* Filter base key signature alg against our configuration */ 1193 return match_list(sshkey_ssh_name(key), 1194 options.pubkey_key_types, NULL); 1195 } 1196 1197 /* 1198 * For RSA keys/certs, since these might have a different sig type: 1199 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1200 * that also appears in the supported signature algorithms list from 1201 * the server. 1202 */ 1203 oallowed = allowed = xstrdup(options.pubkey_key_types); 1204 while ((cp = strsep(&allowed, ",")) != NULL) { 1205 if (sshkey_type_from_name(cp) != key->type) 1206 continue; 1207 tmp = match_list(sshkey_sigalg_by_name(cp), 1208 ssh->kex->server_sig_algs, NULL); 1209 if (tmp != NULL) 1210 alg = xstrdup(cp); 1211 free(tmp); 1212 if (alg != NULL) 1213 break; 1214 } 1215 free(oallowed); 1216 return alg; 1217 } 1218 1219 static int 1220 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1221 const u_char *data, size_t datalen, u_int compat, const char *alg) 1222 { 1223 struct sshkey *sign_key = NULL, *prv = NULL; 1224 int r = SSH_ERR_INTERNAL_ERROR; 1225 struct notifier_ctx *notifier = NULL; 1226 char *fp = NULL, *pin = NULL, *prompt = NULL; 1227 1228 *sigp = NULL; 1229 *lenp = 0; 1230 1231 /* The agent supports this key. */ 1232 if (id->key != NULL && id->agent_fd != -1) { 1233 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1234 data, datalen, alg, compat); 1235 } 1236 1237 /* 1238 * We have already loaded the private key or the private key is 1239 * stored in external hardware. 1240 */ 1241 if (id->key != NULL && 1242 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1243 sign_key = id->key; 1244 } else { 1245 /* Load the private key from the file. */ 1246 if ((prv = load_identity_file(id)) == NULL) 1247 return SSH_ERR_KEY_NOT_FOUND; 1248 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1249 error_f("private key %s contents do not match public", 1250 id->filename); 1251 r = SSH_ERR_KEY_NOT_FOUND; 1252 goto out; 1253 } 1254 sign_key = prv; 1255 if (sshkey_is_sk(sign_key)) { 1256 if ((sign_key->sk_flags & 1257 SSH_SK_USER_VERIFICATION_REQD)) { 1258 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1259 sshkey_type(sign_key), id->filename); 1260 pin = read_passphrase(prompt, 0); 1261 } 1262 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1263 /* XXX should batch mode just skip these? */ 1264 if ((fp = sshkey_fingerprint(sign_key, 1265 options.fingerprint_hash, 1266 SSH_FP_DEFAULT)) == NULL) 1267 fatal_f("fingerprint failed"); 1268 notifier = notify_start(options.batch_mode, 1269 "Confirm user presence for key %s %s", 1270 sshkey_type(sign_key), fp); 1271 free(fp); 1272 } 1273 } 1274 } 1275 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1276 alg, options.sk_provider, pin, compat)) != 0) { 1277 debug_fr(r, "sshkey_sign"); 1278 goto out; 1279 } 1280 /* 1281 * PKCS#11 tokens may not support all signature algorithms, 1282 * so check what we get back. 1283 */ 1284 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1285 debug_fr(r, "sshkey_check_sigtype"); 1286 goto out; 1287 } 1288 /* success */ 1289 r = 0; 1290 out: 1291 free(prompt); 1292 if (pin != NULL) 1293 freezero(pin, strlen(pin)); 1294 notify_complete(notifier, "User presence confirmed"); 1295 sshkey_free(prv); 1296 return r; 1297 } 1298 1299 static int 1300 id_filename_matches(Identity *id, Identity *private_id) 1301 { 1302 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1303 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1304 size_t i, slen; 1305 1306 if (strcmp(id->filename, private_id->filename) == 0) 1307 return 1; 1308 for (i = 0; suffixes[i]; i++) { 1309 slen = strlen(suffixes[i]); 1310 if (len > slen && plen == len - slen && 1311 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1312 memcmp(id->filename, private_id->filename, plen) == 0) 1313 return 1; 1314 } 1315 return 0; 1316 } 1317 1318 static int 1319 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1320 { 1321 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1322 struct sshbuf *b = NULL; 1323 Identity *private_id, *sign_id = NULL; 1324 u_char *signature = NULL; 1325 size_t slen = 0, skip = 0; 1326 int r, fallback_sigtype, sent = 0; 1327 char *alg = NULL, *fp = NULL; 1328 const char *loc = ""; 1329 1330 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1331 SSH_FP_DEFAULT)) == NULL) 1332 return 0; 1333 1334 debug3_f("%s %s", sshkey_type(id->key), fp); 1335 1336 /* 1337 * If the key is an certificate, try to find a matching private key 1338 * and use it to complete the signature. 1339 * If no such private key exists, fall back to trying the certificate 1340 * key itself in case it has a private half already loaded. 1341 * This will try to set sign_id to the private key that will perform 1342 * the signature. 1343 */ 1344 if (sshkey_is_cert(id->key)) { 1345 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1346 if (sshkey_equal_public(id->key, private_id->key) && 1347 id->key->type != private_id->key->type) { 1348 sign_id = private_id; 1349 break; 1350 } 1351 } 1352 /* 1353 * Exact key matches are preferred, but also allow 1354 * filename matches for non-PKCS#11/agent keys that 1355 * didn't load public keys. This supports the case 1356 * of keeping just a private key file and public 1357 * certificate on disk. 1358 */ 1359 if (sign_id == NULL && 1360 !id->isprivate && id->agent_fd == -1 && 1361 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1362 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1363 if (private_id->key == NULL && 1364 id_filename_matches(id, private_id)) { 1365 sign_id = private_id; 1366 break; 1367 } 1368 } 1369 } 1370 if (sign_id != NULL) { 1371 debug2_f("using private key \"%s\"%s for " 1372 "certificate", id->filename, 1373 id->agent_fd != -1 ? " from agent" : ""); 1374 } else { 1375 debug_f("no separate private key for certificate " 1376 "\"%s\"", id->filename); 1377 } 1378 } 1379 1380 /* 1381 * If the above didn't select another identity to do the signing 1382 * then default to the one we started with. 1383 */ 1384 if (sign_id == NULL) 1385 sign_id = id; 1386 1387 /* assemble and sign data */ 1388 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1389 free(alg); 1390 slen = 0; 1391 signature = NULL; 1392 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1393 id->key)) == NULL) { 1394 error_f("no mutual signature supported"); 1395 goto out; 1396 } 1397 debug3_f("signing using %s %s", alg, fp); 1398 1399 sshbuf_free(b); 1400 if ((b = sshbuf_new()) == NULL) 1401 fatal_f("sshbuf_new failed"); 1402 if (datafellows & SSH_OLD_SESSIONID) { 1403 if ((r = sshbuf_put(b, session_id2, 1404 session_id2_len)) != 0) 1405 fatal_fr(r, "sshbuf_put"); 1406 } else { 1407 if ((r = sshbuf_put_string(b, session_id2, 1408 session_id2_len)) != 0) 1409 fatal_fr(r, "sshbuf_put_string"); 1410 } 1411 skip = sshbuf_len(b); 1412 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1413 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1414 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1415 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1416 (r = sshbuf_put_u8(b, 1)) != 0 || 1417 (r = sshbuf_put_cstring(b, alg)) != 0 || 1418 (r = sshkey_puts(id->key, b)) != 0) { 1419 fatal_fr(r, "assemble signed data"); 1420 } 1421 1422 /* generate signature */ 1423 r = identity_sign(sign_id, &signature, &slen, 1424 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1425 if (r == 0) 1426 break; 1427 else if (r == SSH_ERR_KEY_NOT_FOUND) 1428 goto out; /* soft failure */ 1429 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1430 !fallback_sigtype) { 1431 if (sign_id->agent_fd != -1) 1432 loc = "agent "; 1433 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1434 loc = "token "; 1435 logit("%skey %s %s returned incorrect signature type", 1436 loc, sshkey_type(id->key), fp); 1437 continue; 1438 } 1439 error_fr(r, "signing failed for %s \"%s\"%s", 1440 sshkey_type(sign_id->key), sign_id->filename, 1441 id->agent_fd != -1 ? " from agent" : ""); 1442 goto out; 1443 } 1444 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1445 fatal_f("no signature"); 1446 1447 /* append signature */ 1448 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1449 fatal_fr(r, "append signature"); 1450 1451 #ifdef DEBUG_PK 1452 sshbuf_dump(b, stderr); 1453 #endif 1454 /* skip session id and packet type */ 1455 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1456 fatal_fr(r, "consume"); 1457 1458 /* put remaining data from buffer into packet */ 1459 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1460 (r = sshpkt_putb(ssh, b)) != 0 || 1461 (r = sshpkt_send(ssh)) != 0) 1462 fatal_fr(r, "enqueue request"); 1463 1464 /* success */ 1465 sent = 1; 1466 1467 out: 1468 free(fp); 1469 free(alg); 1470 sshbuf_free(b); 1471 freezero(signature, slen); 1472 return sent; 1473 } 1474 1475 static int 1476 send_pubkey_test(struct ssh *ssh, Identity *id) 1477 { 1478 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1479 u_char *blob = NULL; 1480 char *alg = NULL; 1481 size_t bloblen; 1482 u_int have_sig = 0; 1483 int sent = 0, r; 1484 1485 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1486 debug_f("no mutual signature algorithm"); 1487 goto out; 1488 } 1489 1490 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1491 /* we cannot handle this key */ 1492 debug3_f("cannot handle key"); 1493 goto out; 1494 } 1495 /* register callback for USERAUTH_PK_OK message */ 1496 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1497 1498 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1499 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1500 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1501 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1502 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1503 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1504 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1505 (r = sshpkt_send(ssh)) != 0) 1506 fatal_fr(r, "send packet"); 1507 sent = 1; 1508 1509 out: 1510 free(alg); 1511 free(blob); 1512 return sent; 1513 } 1514 1515 static struct sshkey * 1516 load_identity_file(Identity *id) 1517 { 1518 struct sshkey *private = NULL; 1519 char prompt[300], *passphrase, *comment; 1520 int r, quit = 0, i; 1521 struct stat st; 1522 1523 if (stat(id->filename, &st) == -1) { 1524 do_log2(id->userprovided ? 1525 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1526 "no such identity: %s: %s", id->filename, strerror(errno)); 1527 return NULL; 1528 } 1529 snprintf(prompt, sizeof prompt, 1530 "Enter passphrase for key '%.100s': ", id->filename); 1531 for (i = 0; i <= options.number_of_password_prompts; i++) { 1532 if (i == 0) 1533 passphrase = ""; 1534 else { 1535 passphrase = read_passphrase(prompt, 0); 1536 if (*passphrase == '\0') { 1537 debug2("no passphrase given, try next key"); 1538 free(passphrase); 1539 break; 1540 } 1541 } 1542 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1543 passphrase, &private, &comment))) { 1544 case 0: 1545 break; 1546 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1547 if (options.batch_mode) { 1548 quit = 1; 1549 break; 1550 } 1551 if (i != 0) 1552 debug2("bad passphrase given, try again..."); 1553 break; 1554 case SSH_ERR_SYSTEM_ERROR: 1555 if (errno == ENOENT) { 1556 debug2_r(r, "Load key \"%s\"", id->filename); 1557 quit = 1; 1558 break; 1559 } 1560 /* FALLTHROUGH */ 1561 default: 1562 error_r(r, "Load key \"%s\"", id->filename); 1563 quit = 1; 1564 break; 1565 } 1566 if (private != NULL && sshkey_is_sk(private) && 1567 options.sk_provider == NULL) { 1568 debug("key \"%s\" is an authenticator-hosted key, " 1569 "but no provider specified", id->filename); 1570 sshkey_free(private); 1571 private = NULL; 1572 quit = 1; 1573 } 1574 if (!quit && private != NULL && id->agent_fd == -1 && 1575 !(id->key && id->isprivate)) 1576 maybe_add_key_to_agent(id->filename, private, comment, 1577 passphrase); 1578 if (i > 0) 1579 freezero(passphrase, strlen(passphrase)); 1580 free(comment); 1581 if (private != NULL || quit) 1582 break; 1583 } 1584 return private; 1585 } 1586 1587 static int 1588 key_type_allowed_by_config(struct sshkey *key) 1589 { 1590 if (match_pattern_list(sshkey_ssh_name(key), 1591 options.pubkey_key_types, 0) == 1) 1592 return 1; 1593 1594 /* RSA keys/certs might be allowed by alternate signature types */ 1595 switch (key->type) { 1596 case KEY_RSA: 1597 if (match_pattern_list("rsa-sha2-512", 1598 options.pubkey_key_types, 0) == 1) 1599 return 1; 1600 if (match_pattern_list("rsa-sha2-256", 1601 options.pubkey_key_types, 0) == 1) 1602 return 1; 1603 break; 1604 case KEY_RSA_CERT: 1605 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1606 options.pubkey_key_types, 0) == 1) 1607 return 1; 1608 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1609 options.pubkey_key_types, 0) == 1) 1610 return 1; 1611 break; 1612 } 1613 return 0; 1614 } 1615 1616 1617 /* 1618 * try keys in the following order: 1619 * 1. certificates listed in the config file 1620 * 2. other input certificates 1621 * 3. agent keys that are found in the config file 1622 * 4. other agent keys 1623 * 5. keys that are only listed in the config file 1624 */ 1625 static void 1626 pubkey_prepare(Authctxt *authctxt) 1627 { 1628 struct identity *id, *id2, *tmp; 1629 struct idlist agent, files, *preferred; 1630 struct sshkey *key; 1631 int agent_fd = -1, i, r, found; 1632 size_t j; 1633 struct ssh_identitylist *idlist; 1634 char *ident; 1635 1636 TAILQ_INIT(&agent); /* keys from the agent */ 1637 TAILQ_INIT(&files); /* keys from the config file */ 1638 preferred = &authctxt->keys; 1639 TAILQ_INIT(preferred); /* preferred order of keys */ 1640 1641 /* list of keys stored in the filesystem and PKCS#11 */ 1642 for (i = 0; i < options.num_identity_files; i++) { 1643 key = options.identity_keys[i]; 1644 if (key && key->cert && 1645 key->cert->type != SSH2_CERT_TYPE_USER) { 1646 debug_f("ignoring certificate %s: not a user " 1647 "certificate", options.identity_files[i]); 1648 continue; 1649 } 1650 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1651 debug_f("ignoring authenticator-hosted key %s as no " 1652 "SecurityKeyProvider has been specified", 1653 options.identity_files[i]); 1654 continue; 1655 } 1656 options.identity_keys[i] = NULL; 1657 id = xcalloc(1, sizeof(*id)); 1658 id->agent_fd = -1; 1659 id->key = key; 1660 id->filename = xstrdup(options.identity_files[i]); 1661 id->userprovided = options.identity_file_userprovided[i]; 1662 TAILQ_INSERT_TAIL(&files, id, next); 1663 } 1664 /* list of certificates specified by user */ 1665 for (i = 0; i < options.num_certificate_files; i++) { 1666 key = options.certificates[i]; 1667 if (!sshkey_is_cert(key) || key->cert == NULL || 1668 key->cert->type != SSH2_CERT_TYPE_USER) { 1669 debug_f("ignoring certificate %s: not a user " 1670 "certificate", options.identity_files[i]); 1671 continue; 1672 } 1673 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1674 debug_f("ignoring authenticator-hosted key " 1675 "certificate %s as no " 1676 "SecurityKeyProvider has been specified", 1677 options.identity_files[i]); 1678 continue; 1679 } 1680 id = xcalloc(1, sizeof(*id)); 1681 id->agent_fd = -1; 1682 id->key = key; 1683 id->filename = xstrdup(options.certificate_files[i]); 1684 id->userprovided = options.certificate_file_userprovided[i]; 1685 TAILQ_INSERT_TAIL(preferred, id, next); 1686 } 1687 /* list of keys supported by the agent */ 1688 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1689 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1690 debug_fr(r, "ssh_get_authentication_socket"); 1691 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1692 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1693 debug_fr(r, "ssh_fetch_identitylist"); 1694 close(agent_fd); 1695 } else { 1696 for (j = 0; j < idlist->nkeys; j++) { 1697 found = 0; 1698 TAILQ_FOREACH(id, &files, next) { 1699 /* 1700 * agent keys from the config file are 1701 * preferred 1702 */ 1703 if (sshkey_equal(idlist->keys[j], id->key)) { 1704 TAILQ_REMOVE(&files, id, next); 1705 TAILQ_INSERT_TAIL(preferred, id, next); 1706 id->agent_fd = agent_fd; 1707 found = 1; 1708 break; 1709 } 1710 } 1711 if (!found && !options.identities_only) { 1712 id = xcalloc(1, sizeof(*id)); 1713 /* XXX "steals" key/comment from idlist */ 1714 id->key = idlist->keys[j]; 1715 id->filename = idlist->comments[j]; 1716 idlist->keys[j] = NULL; 1717 idlist->comments[j] = NULL; 1718 id->agent_fd = agent_fd; 1719 TAILQ_INSERT_TAIL(&agent, id, next); 1720 } 1721 } 1722 ssh_free_identitylist(idlist); 1723 /* append remaining agent keys */ 1724 TAILQ_CONCAT(preferred, &agent, next); 1725 authctxt->agent_fd = agent_fd; 1726 } 1727 /* Prefer PKCS11 keys that are explicitly listed */ 1728 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1729 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1730 continue; 1731 found = 0; 1732 TAILQ_FOREACH(id2, &files, next) { 1733 if (id2->key == NULL || 1734 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1735 continue; 1736 if (sshkey_equal(id->key, id2->key)) { 1737 TAILQ_REMOVE(&files, id, next); 1738 TAILQ_INSERT_TAIL(preferred, id, next); 1739 found = 1; 1740 break; 1741 } 1742 } 1743 /* If IdentitiesOnly set and key not found then don't use it */ 1744 if (!found && options.identities_only) { 1745 TAILQ_REMOVE(&files, id, next); 1746 freezero(id, sizeof(*id)); 1747 } 1748 } 1749 /* append remaining keys from the config file */ 1750 TAILQ_CONCAT(preferred, &files, next); 1751 /* finally, filter by PubkeyAcceptedKeyTypes */ 1752 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1753 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1754 debug("Skipping %s key %s - " 1755 "not in PubkeyAcceptedKeyTypes", 1756 sshkey_ssh_name(id->key), id->filename); 1757 TAILQ_REMOVE(preferred, id, next); 1758 sshkey_free(id->key); 1759 free(id->filename); 1760 memset(id, 0, sizeof(*id)); 1761 continue; 1762 } 1763 } 1764 /* List the keys we plan on using */ 1765 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1766 ident = format_identity(id); 1767 debug("Will attempt key: %s", ident); 1768 free(ident); 1769 } 1770 debug2_f("done"); 1771 } 1772 1773 static void 1774 pubkey_cleanup(struct ssh *ssh) 1775 { 1776 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1777 Identity *id; 1778 1779 if (authctxt->agent_fd != -1) { 1780 ssh_close_authentication_socket(authctxt->agent_fd); 1781 authctxt->agent_fd = -1; 1782 } 1783 for (id = TAILQ_FIRST(&authctxt->keys); id; 1784 id = TAILQ_FIRST(&authctxt->keys)) { 1785 TAILQ_REMOVE(&authctxt->keys, id, next); 1786 sshkey_free(id->key); 1787 free(id->filename); 1788 free(id); 1789 } 1790 } 1791 1792 static void 1793 pubkey_reset(Authctxt *authctxt) 1794 { 1795 Identity *id; 1796 1797 TAILQ_FOREACH(id, &authctxt->keys, next) 1798 id->tried = 0; 1799 } 1800 1801 static int 1802 try_identity(Identity *id) 1803 { 1804 if (!id->key) 1805 return (0); 1806 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1807 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1808 debug("Skipped %s key %s for RSA/MD5 server", 1809 sshkey_type(id->key), id->filename); 1810 return (0); 1811 } 1812 return 1; 1813 } 1814 1815 static int 1816 userauth_pubkey(struct ssh *ssh) 1817 { 1818 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1819 Identity *id; 1820 int sent = 0; 1821 char *ident; 1822 1823 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1824 if (id->tried++) 1825 return (0); 1826 /* move key to the end of the queue */ 1827 TAILQ_REMOVE(&authctxt->keys, id, next); 1828 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1829 /* 1830 * send a test message if we have the public key. for 1831 * encrypted keys we cannot do this and have to load the 1832 * private key instead 1833 */ 1834 if (id->key != NULL) { 1835 if (try_identity(id)) { 1836 ident = format_identity(id); 1837 debug("Offering public key: %s", ident); 1838 free(ident); 1839 sent = send_pubkey_test(ssh, id); 1840 } 1841 } else { 1842 debug("Trying private key: %s", id->filename); 1843 id->key = load_identity_file(id); 1844 if (id->key != NULL) { 1845 if (try_identity(id)) { 1846 id->isprivate = 1; 1847 sent = sign_and_send_pubkey(ssh, id); 1848 } 1849 sshkey_free(id->key); 1850 id->key = NULL; 1851 id->isprivate = 0; 1852 } 1853 } 1854 if (sent) 1855 return (sent); 1856 } 1857 return (0); 1858 } 1859 1860 /* 1861 * Send userauth request message specifying keyboard-interactive method. 1862 */ 1863 static int 1864 userauth_kbdint(struct ssh *ssh) 1865 { 1866 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1867 int r; 1868 1869 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1870 return 0; 1871 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1872 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1873 debug3("userauth_kbdint: disable: no info_req_seen"); 1874 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1875 return 0; 1876 } 1877 1878 debug2("userauth_kbdint"); 1879 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1880 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1881 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1882 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1883 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1884 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1885 options.kbd_interactive_devices : "")) != 0 || 1886 (r = sshpkt_send(ssh)) != 0) 1887 fatal_fr(r, "send packet"); 1888 1889 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1890 return 1; 1891 } 1892 1893 /* 1894 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1895 */ 1896 static int 1897 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1898 { 1899 Authctxt *authctxt = ssh->authctxt; 1900 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1901 char *display_prompt = NULL, *response = NULL; 1902 u_char echo = 0; 1903 u_int num_prompts, i; 1904 int r; 1905 1906 debug2_f("entering"); 1907 1908 if (authctxt == NULL) 1909 fatal_f("no authentication context"); 1910 1911 authctxt->info_req_seen = 1; 1912 1913 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1914 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1915 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1916 goto out; 1917 if (strlen(name) > 0) 1918 logit("%s", name); 1919 if (strlen(inst) > 0) 1920 logit("%s", inst); 1921 1922 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1923 goto out; 1924 /* 1925 * Begin to build info response packet based on prompts requested. 1926 * We commit to providing the correct number of responses, so if 1927 * further on we run into a problem that prevents this, we have to 1928 * be sure and clean this up and send a correct error response. 1929 */ 1930 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1931 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1932 goto out; 1933 1934 debug2_f("num_prompts %d", num_prompts); 1935 for (i = 0; i < num_prompts; i++) { 1936 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1937 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1938 goto out; 1939 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1940 authctxt->server_user, options.host_key_alias ? 1941 options.host_key_alias : authctxt->host, prompt) == -1) 1942 fatal_f("asmprintf failed"); 1943 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1944 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1945 goto out; 1946 freezero(response, strlen(response)); 1947 free(prompt); 1948 free(display_prompt); 1949 display_prompt = response = prompt = NULL; 1950 } 1951 /* done with parsing incoming message. */ 1952 if ((r = sshpkt_get_end(ssh)) != 0 || 1953 (r = sshpkt_add_padding(ssh, 64)) != 0) 1954 goto out; 1955 r = sshpkt_send(ssh); 1956 out: 1957 if (response) 1958 freezero(response, strlen(response)); 1959 free(prompt); 1960 free(display_prompt); 1961 free(name); 1962 free(inst); 1963 free(lang); 1964 return r; 1965 } 1966 1967 static int 1968 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1969 const u_char *data, size_t datalen) 1970 { 1971 struct sshbuf *b; 1972 struct stat st; 1973 pid_t pid; 1974 int r, to[2], from[2], status; 1975 int sock = ssh_packet_get_connection_in(ssh); 1976 u_char rversion = 0, version = 2; 1977 void (*osigchld)(int); 1978 1979 *sigp = NULL; 1980 *lenp = 0; 1981 1982 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1983 error_f("not installed: %s", strerror(errno)); 1984 return -1; 1985 } 1986 if (fflush(stdout) != 0) { 1987 error_f("fflush: %s", strerror(errno)); 1988 return -1; 1989 } 1990 if (pipe(to) == -1) { 1991 error_f("pipe: %s", strerror(errno)); 1992 return -1; 1993 } 1994 if (pipe(from) == -1) { 1995 error_f("pipe: %s", strerror(errno)); 1996 return -1; 1997 } 1998 if ((pid = fork()) == -1) { 1999 error_f("fork: %s", strerror(errno)); 2000 return -1; 2001 } 2002 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2003 if (pid == 0) { 2004 close(from[0]); 2005 if (dup2(from[1], STDOUT_FILENO) == -1) 2006 fatal_f("dup2: %s", strerror(errno)); 2007 close(to[1]); 2008 if (dup2(to[0], STDIN_FILENO) == -1) 2009 fatal_f("dup2: %s", strerror(errno)); 2010 close(from[1]); 2011 close(to[0]); 2012 2013 if (dup2(sock, STDERR_FILENO + 1) == -1) 2014 fatal_f("dup2: %s", strerror(errno)); 2015 sock = STDERR_FILENO + 1; 2016 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2017 closefrom(sock + 1); 2018 2019 debug3_f("[child] pid=%ld, exec %s", 2020 (long)getpid(), _PATH_SSH_KEY_SIGN); 2021 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2022 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2023 strerror(errno)); 2024 } 2025 close(from[1]); 2026 close(to[0]); 2027 sock = STDERR_FILENO + 1; 2028 2029 if ((b = sshbuf_new()) == NULL) 2030 fatal_f("sshbuf_new failed"); 2031 /* send # of sock, data to be signed */ 2032 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2033 (r = sshbuf_put_string(b, data, datalen)) != 0) 2034 fatal_fr(r, "buffer error"); 2035 if (ssh_msg_send(to[1], version, b) == -1) 2036 fatal_f("couldn't send request"); 2037 sshbuf_reset(b); 2038 r = ssh_msg_recv(from[0], b); 2039 close(from[0]); 2040 close(to[1]); 2041 if (r < 0) { 2042 error_f("no reply"); 2043 goto fail; 2044 } 2045 2046 errno = 0; 2047 while (waitpid(pid, &status, 0) == -1) { 2048 if (errno != EINTR) { 2049 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2050 goto fail; 2051 } 2052 } 2053 if (!WIFEXITED(status)) { 2054 error_f("exited abnormally"); 2055 goto fail; 2056 } 2057 if (WEXITSTATUS(status) != 0) { 2058 error_f("exited with status %d", WEXITSTATUS(status)); 2059 goto fail; 2060 } 2061 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2062 error_fr(r, "buffer error"); 2063 goto fail; 2064 } 2065 if (rversion != version) { 2066 error_f("bad version"); 2067 goto fail; 2068 } 2069 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2070 error_fr(r, "buffer error"); 2071 fail: 2072 ssh_signal(SIGCHLD, osigchld); 2073 sshbuf_free(b); 2074 return -1; 2075 } 2076 ssh_signal(SIGCHLD, osigchld); 2077 sshbuf_free(b); 2078 2079 return 0; 2080 } 2081 2082 static int 2083 userauth_hostbased(struct ssh *ssh) 2084 { 2085 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2086 struct sshkey *private = NULL; 2087 struct sshbuf *b = NULL; 2088 u_char *sig = NULL, *keyblob = NULL; 2089 char *fp = NULL, *chost = NULL, *lname = NULL; 2090 size_t siglen = 0, keylen = 0; 2091 int i, r, success = 0; 2092 2093 if (authctxt->ktypes == NULL) { 2094 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2095 authctxt->ktypes = authctxt->oktypes; 2096 } 2097 2098 /* 2099 * Work through each listed type pattern in HostbasedKeyTypes, 2100 * trying each hostkey that matches the type in turn. 2101 */ 2102 for (;;) { 2103 if (authctxt->active_ktype == NULL) 2104 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2105 if (authctxt->active_ktype == NULL || 2106 *authctxt->active_ktype == '\0') 2107 break; 2108 debug3_f("trying key type %s", authctxt->active_ktype); 2109 2110 /* check for a useful key */ 2111 private = NULL; 2112 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2113 if (authctxt->sensitive->keys[i] == NULL || 2114 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2115 continue; 2116 if (match_pattern_list( 2117 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2118 authctxt->active_ktype, 0) != 1) 2119 continue; 2120 /* we take and free the key */ 2121 private = authctxt->sensitive->keys[i]; 2122 authctxt->sensitive->keys[i] = NULL; 2123 break; 2124 } 2125 /* Found one */ 2126 if (private != NULL) 2127 break; 2128 /* No more keys of this type; advance */ 2129 authctxt->active_ktype = NULL; 2130 } 2131 if (private == NULL) { 2132 free(authctxt->oktypes); 2133 authctxt->oktypes = authctxt->ktypes = NULL; 2134 authctxt->active_ktype = NULL; 2135 debug("No more client hostkeys for hostbased authentication."); 2136 goto out; 2137 } 2138 2139 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2140 SSH_FP_DEFAULT)) == NULL) { 2141 error_f("sshkey_fingerprint failed"); 2142 goto out; 2143 } 2144 debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp); 2145 2146 /* figure out a name for the client host */ 2147 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2148 if (lname == NULL) { 2149 error_f("cannot get local ipaddr/name"); 2150 goto out; 2151 } 2152 2153 /* XXX sshbuf_put_stringf? */ 2154 xasprintf(&chost, "%s.", lname); 2155 debug2_f("chost %s", chost); 2156 2157 /* construct data */ 2158 if ((b = sshbuf_new()) == NULL) { 2159 error_f("sshbuf_new failed"); 2160 goto out; 2161 } 2162 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2163 error_fr(r, "sshkey_to_blob"); 2164 goto out; 2165 } 2166 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2167 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2168 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2169 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2170 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2171 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2172 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2173 (r = sshbuf_put_cstring(b, chost)) != 0 || 2174 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2175 error_fr(r, "buffer error"); 2176 goto out; 2177 } 2178 2179 #ifdef DEBUG_PK 2180 sshbuf_dump(b, stderr); 2181 #endif 2182 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2183 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2184 error("sign using hostkey %s %s failed", 2185 sshkey_ssh_name(private), fp); 2186 goto out; 2187 } 2188 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2189 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2190 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2191 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2192 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2193 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2194 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2195 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2196 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2197 (r = sshpkt_send(ssh)) != 0) { 2198 error_fr(r, "packet error"); 2199 goto out; 2200 } 2201 success = 1; 2202 2203 out: 2204 if (sig != NULL) 2205 freezero(sig, siglen); 2206 free(keyblob); 2207 free(lname); 2208 free(fp); 2209 free(chost); 2210 sshkey_free(private); 2211 sshbuf_free(b); 2212 2213 return success; 2214 } 2215 2216 /* find auth method */ 2217 2218 /* 2219 * given auth method name, if configurable options permit this method fill 2220 * in auth_ident field and return true, otherwise return false. 2221 */ 2222 static int 2223 authmethod_is_enabled(Authmethod *method) 2224 { 2225 if (method == NULL) 2226 return 0; 2227 /* return false if options indicate this method is disabled */ 2228 if (method->enabled == NULL || *method->enabled == 0) 2229 return 0; 2230 /* return false if batch mode is enabled but method needs interactive mode */ 2231 if (method->batch_flag != NULL && *method->batch_flag != 0) 2232 return 0; 2233 return 1; 2234 } 2235 2236 static Authmethod * 2237 authmethod_lookup(const char *name) 2238 { 2239 Authmethod *method = NULL; 2240 if (name != NULL) 2241 for (method = authmethods; method->name != NULL; method++) 2242 if (strcmp(name, method->name) == 0) 2243 return method; 2244 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2245 return NULL; 2246 } 2247 2248 /* XXX internal state */ 2249 static Authmethod *current = NULL; 2250 static char *supported = NULL; 2251 static char *preferred = NULL; 2252 2253 /* 2254 * Given the authentication method list sent by the server, return the 2255 * next method we should try. If the server initially sends a nil list, 2256 * use a built-in default list. 2257 */ 2258 static Authmethod * 2259 authmethod_get(char *authlist) 2260 { 2261 char *name = NULL; 2262 u_int next; 2263 2264 /* Use a suitable default if we're passed a nil list. */ 2265 if (authlist == NULL || strlen(authlist) == 0) 2266 authlist = options.preferred_authentications; 2267 2268 if (supported == NULL || strcmp(authlist, supported) != 0) { 2269 debug3("start over, passed a different list %s", authlist); 2270 free(supported); 2271 supported = xstrdup(authlist); 2272 preferred = options.preferred_authentications; 2273 debug3("preferred %s", preferred); 2274 current = NULL; 2275 } else if (current != NULL && authmethod_is_enabled(current)) 2276 return current; 2277 2278 for (;;) { 2279 if ((name = match_list(preferred, supported, &next)) == NULL) { 2280 debug("No more authentication methods to try."); 2281 current = NULL; 2282 return NULL; 2283 } 2284 preferred += next; 2285 debug3("authmethod_lookup %s", name); 2286 debug3("remaining preferred: %s", preferred); 2287 if ((current = authmethod_lookup(name)) != NULL && 2288 authmethod_is_enabled(current)) { 2289 debug3("authmethod_is_enabled %s", name); 2290 debug("Next authentication method: %s", name); 2291 free(name); 2292 return current; 2293 } 2294 free(name); 2295 } 2296 } 2297 2298 static char * 2299 authmethods_get(void) 2300 { 2301 Authmethod *method = NULL; 2302 struct sshbuf *b; 2303 char *list; 2304 int r; 2305 2306 if ((b = sshbuf_new()) == NULL) 2307 fatal_f("sshbuf_new failed"); 2308 for (method = authmethods; method->name != NULL; method++) { 2309 if (authmethod_is_enabled(method)) { 2310 if ((r = sshbuf_putf(b, "%s%s", 2311 sshbuf_len(b) ? "," : "", method->name)) != 0) 2312 fatal_fr(r, "buffer error"); 2313 } 2314 } 2315 if ((list = sshbuf_dup_string(b)) == NULL) 2316 fatal_f("sshbuf_dup_string failed"); 2317 sshbuf_free(b); 2318 return list; 2319 } 2320