1 /* $OpenBSD: sshconnect2.c,v 1.333 2020/10/30 01:50:07 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_f("have matching best-preference key type %s, " 147 "using HostkeyAlgorithms verbatim", 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_f("unknown alg %s", 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_f("prefer hostkeyalgs: %s", 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 ((r = kex_assemble_names(&options.hostkeyalgorithms, 231 kex_default_pk_alg(), all_key)) != 0) 232 fatal_fr(r, "kex_assemble_namelist"); 233 free(all_key); 234 235 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 236 fatal_f("kex_names_cat"); 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_r(r, "kex_setup"); 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_r(r, "kex_prop2buf"); 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_fr(r, "send packet"); 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_f("internal error: cannot send userauth none request"); 467 } 468 469 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 470 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 471 (r = sshpkt_send(ssh)) != 0) 472 fatal_fr(r, "send packet"); 473 474 ssh->authctxt = &authctxt; 475 ssh_dispatch_init(ssh, &input_userauth_error); 476 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 477 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 478 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 479 pubkey_cleanup(ssh); 480 ssh->authctxt = NULL; 481 482 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 483 484 if (!authctxt.success) 485 fatal("Authentication failed."); 486 debug("Authentication succeeded (%s).", authctxt.method->name); 487 } 488 489 /* ARGSUSED */ 490 static int 491 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 492 { 493 int r; 494 495 if (ssh_packet_remaining(ssh) > 0) { 496 char *reply; 497 498 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 499 goto out; 500 debug2("service_accept: %s", reply); 501 free(reply); 502 } else { 503 debug2("buggy server: service_accept w/o service"); 504 } 505 if ((r = sshpkt_get_end(ssh)) != 0) 506 goto out; 507 debug("SSH2_MSG_SERVICE_ACCEPT received"); 508 509 /* initial userauth request */ 510 userauth_none(ssh); 511 512 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 513 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 514 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 515 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 516 r = 0; 517 out: 518 return r; 519 } 520 521 /* ARGSUSED */ 522 static int 523 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 524 { 525 return kex_input_ext_info(type, seqnr, ssh); 526 } 527 528 void 529 userauth(struct ssh *ssh, char *authlist) 530 { 531 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 532 533 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 534 authctxt->method->cleanup(ssh); 535 536 free(authctxt->methoddata); 537 authctxt->methoddata = NULL; 538 if (authlist == NULL) { 539 authlist = authctxt->authlist; 540 } else { 541 free(authctxt->authlist); 542 authctxt->authlist = authlist; 543 } 544 for (;;) { 545 Authmethod *method = authmethod_get(authlist); 546 if (method == NULL) 547 fatal("%s@%s: Permission denied (%s).", 548 authctxt->server_user, authctxt->host, authlist); 549 authctxt->method = method; 550 551 /* reset the per method handler */ 552 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 553 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 554 555 /* and try new method */ 556 if (method->userauth(ssh) != 0) { 557 debug2("we sent a %s packet, wait for reply", method->name); 558 break; 559 } else { 560 debug2("we did not send a packet, disable method"); 561 method->enabled = NULL; 562 } 563 } 564 } 565 566 /* ARGSUSED */ 567 static int 568 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 569 { 570 fatal_f("bad message during authentication: type %d", type); 571 return 0; 572 } 573 574 /* ARGSUSED */ 575 static int 576 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 577 { 578 char *msg = NULL; 579 size_t len; 580 int r; 581 582 debug3_f("entering"); 583 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 584 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 585 goto out; 586 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 587 fmprintf(stderr, "%s", msg); 588 r = 0; 589 out: 590 free(msg); 591 return r; 592 } 593 594 /* ARGSUSED */ 595 static int 596 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 597 { 598 Authctxt *authctxt = ssh->authctxt; 599 600 if (authctxt == NULL) 601 fatal_f("no authentication context"); 602 free(authctxt->authlist); 603 authctxt->authlist = NULL; 604 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 605 authctxt->method->cleanup(ssh); 606 free(authctxt->methoddata); 607 authctxt->methoddata = NULL; 608 authctxt->success = 1; /* break out */ 609 return 0; 610 } 611 612 #if 0 613 static int 614 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 615 { 616 Authctxt *authctxt = ssh->authctxt; 617 618 if (authctxt == NULL) 619 fatal_f("no authentication context"); 620 621 fatal("Unexpected authentication success during %s.", 622 authctxt->method->name); 623 return 0; 624 } 625 #endif 626 627 /* ARGSUSED */ 628 static int 629 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 630 { 631 Authctxt *authctxt = ssh->authctxt; 632 char *authlist = NULL; 633 u_char partial; 634 635 if (authctxt == NULL) 636 fatal("input_userauth_failure: no authentication context"); 637 638 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 639 sshpkt_get_u8(ssh, &partial) != 0 || 640 sshpkt_get_end(ssh) != 0) 641 goto out; 642 643 if (partial != 0) { 644 verbose("Authenticated with partial success."); 645 /* reset state */ 646 pubkey_reset(authctxt); 647 } 648 debug("Authentications that can continue: %s", authlist); 649 650 userauth(ssh, authlist); 651 authlist = NULL; 652 out: 653 free(authlist); 654 return 0; 655 } 656 657 /* 658 * Format an identity for logging including filename, key type, fingerprint 659 * and location (agent, etc.). Caller must free. 660 */ 661 static char * 662 format_identity(Identity *id) 663 { 664 char *fp = NULL, *ret = NULL; 665 const char *note = ""; 666 667 if (id->key != NULL) { 668 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 669 SSH_FP_DEFAULT); 670 } 671 if (id->key) { 672 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 673 note = " token"; 674 else if (sshkey_is_sk(id->key)) 675 note = " authenticator"; 676 } 677 xasprintf(&ret, "%s %s%s%s%s%s%s", 678 id->filename, 679 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 680 fp ? fp : "", 681 id->userprovided ? " explicit" : "", note, 682 id->agent_fd != -1 ? " agent" : ""); 683 free(fp); 684 return ret; 685 } 686 687 /* ARGSUSED */ 688 static int 689 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 690 { 691 Authctxt *authctxt = ssh->authctxt; 692 struct sshkey *key = NULL; 693 Identity *id = NULL; 694 int pktype, found = 0, sent = 0; 695 size_t blen; 696 char *pkalg = NULL, *fp = NULL, *ident = NULL; 697 u_char *pkblob = NULL; 698 int r; 699 700 if (authctxt == NULL) 701 fatal("input_userauth_pk_ok: no authentication context"); 702 703 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 704 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 705 (r = sshpkt_get_end(ssh)) != 0) 706 goto done; 707 708 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 709 debug_f("server sent unknown pkalg %s", pkalg); 710 goto done; 711 } 712 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 713 debug_r(r, "no key from blob. pkalg %s", pkalg); 714 goto done; 715 } 716 if (key->type != pktype) { 717 error("input_userauth_pk_ok: type mismatch " 718 "for decoded key (received %d, expected %d)", 719 key->type, pktype); 720 goto done; 721 } 722 723 /* 724 * search keys in the reverse order, because last candidate has been 725 * moved to the end of the queue. this also avoids confusion by 726 * duplicate keys 727 */ 728 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 729 if (sshkey_equal(key, id->key)) { 730 found = 1; 731 break; 732 } 733 } 734 if (!found || id == NULL) { 735 fp = sshkey_fingerprint(key, options.fingerprint_hash, 736 SSH_FP_DEFAULT); 737 error_f("server replied with unknown key: %s %s", 738 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 739 goto done; 740 } 741 ident = format_identity(id); 742 debug("Server accepts key: %s", ident); 743 sent = sign_and_send_pubkey(ssh, id); 744 r = 0; 745 done: 746 sshkey_free(key); 747 free(ident); 748 free(fp); 749 free(pkalg); 750 free(pkblob); 751 752 /* try another method if we did not send a packet */ 753 if (r == 0 && sent == 0) 754 userauth(ssh, NULL); 755 return r; 756 } 757 758 #ifdef GSSAPI 759 static int 760 userauth_gssapi(struct ssh *ssh) 761 { 762 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 763 Gssctxt *gssctxt = NULL; 764 OM_uint32 min; 765 int r, ok = 0; 766 gss_OID mech = NULL; 767 768 /* Try one GSSAPI method at a time, rather than sending them all at 769 * once. */ 770 771 if (authctxt->gss_supported_mechs == NULL) 772 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 773 774 /* Check to see whether the mechanism is usable before we offer it */ 775 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 776 !ok) { 777 mech = &authctxt->gss_supported_mechs-> 778 elements[authctxt->mech_tried]; 779 /* My DER encoding requires length<128 */ 780 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 781 mech, authctxt->host)) { 782 ok = 1; /* Mechanism works */ 783 } else { 784 authctxt->mech_tried++; 785 } 786 } 787 788 if (!ok || mech == NULL) 789 return 0; 790 791 authctxt->methoddata=(void *)gssctxt; 792 793 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 794 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 795 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 796 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 797 (r = sshpkt_put_u32(ssh, 1)) != 0 || 798 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 799 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 800 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 801 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 802 (r = sshpkt_send(ssh)) != 0) 803 fatal_fr(r, "send packet"); 804 805 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 806 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 807 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 808 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 809 810 authctxt->mech_tried++; /* Move along to next candidate */ 811 812 return 1; 813 } 814 815 static void 816 userauth_gssapi_cleanup(struct ssh *ssh) 817 { 818 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 819 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 820 821 ssh_gssapi_delete_ctx(&gssctxt); 822 authctxt->methoddata = NULL; 823 824 free(authctxt->gss_supported_mechs); 825 authctxt->gss_supported_mechs = NULL; 826 } 827 828 static OM_uint32 829 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 830 { 831 Authctxt *authctxt = ssh->authctxt; 832 Gssctxt *gssctxt = authctxt->methoddata; 833 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 834 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 835 gss_buffer_desc gssbuf; 836 OM_uint32 status, ms, flags; 837 int r; 838 839 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 840 recv_tok, &send_tok, &flags); 841 842 if (send_tok.length > 0) { 843 u_char type = GSS_ERROR(status) ? 844 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 845 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 846 847 if ((r = sshpkt_start(ssh, type)) != 0 || 848 (r = sshpkt_put_string(ssh, send_tok.value, 849 send_tok.length)) != 0 || 850 (r = sshpkt_send(ssh)) != 0) 851 fatal_fr(r, "send %u packet", type); 852 853 gss_release_buffer(&ms, &send_tok); 854 } 855 856 if (status == GSS_S_COMPLETE) { 857 /* send either complete or MIC, depending on mechanism */ 858 if (!(flags & GSS_C_INTEG_FLAG)) { 859 if ((r = sshpkt_start(ssh, 860 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 861 (r = sshpkt_send(ssh)) != 0) 862 fatal_fr(r, "send completion"); 863 } else { 864 struct sshbuf *b; 865 866 if ((b = sshbuf_new()) == NULL) 867 fatal_f("sshbuf_new failed"); 868 ssh_gssapi_buildmic(b, authctxt->server_user, 869 authctxt->service, "gssapi-with-mic"); 870 871 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 872 fatal_f("sshbuf_mutable_ptr failed"); 873 gssbuf.length = sshbuf_len(b); 874 875 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 876 877 if (!GSS_ERROR(status)) { 878 if ((r = sshpkt_start(ssh, 879 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 880 (r = sshpkt_put_string(ssh, mic.value, 881 mic.length)) != 0 || 882 (r = sshpkt_send(ssh)) != 0) 883 fatal_fr(r, "send MIC"); 884 } 885 886 sshbuf_free(b); 887 gss_release_buffer(&ms, &mic); 888 } 889 } 890 891 return status; 892 } 893 894 /* ARGSUSED */ 895 static int 896 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 897 { 898 Authctxt *authctxt = ssh->authctxt; 899 Gssctxt *gssctxt; 900 size_t oidlen; 901 u_char *oidv = NULL; 902 int r; 903 904 if (authctxt == NULL) 905 fatal("input_gssapi_response: no authentication context"); 906 gssctxt = authctxt->methoddata; 907 908 /* Setup our OID */ 909 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 910 goto done; 911 912 if (oidlen <= 2 || 913 oidv[0] != SSH_GSS_OIDTYPE || 914 oidv[1] != oidlen - 2) { 915 debug("Badly encoded mechanism OID received"); 916 userauth(ssh, NULL); 917 goto ok; 918 } 919 920 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 921 fatal("Server returned different OID than expected"); 922 923 if ((r = sshpkt_get_end(ssh)) != 0) 924 goto done; 925 926 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 927 /* Start again with next method on list */ 928 debug("Trying to start again"); 929 userauth(ssh, NULL); 930 goto ok; 931 } 932 ok: 933 r = 0; 934 done: 935 free(oidv); 936 return r; 937 } 938 939 /* ARGSUSED */ 940 static int 941 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 942 { 943 Authctxt *authctxt = ssh->authctxt; 944 gss_buffer_desc recv_tok; 945 u_char *p = NULL; 946 size_t len; 947 OM_uint32 status; 948 int r; 949 950 if (authctxt == NULL) 951 fatal("input_gssapi_response: no authentication context"); 952 953 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 954 (r = sshpkt_get_end(ssh)) != 0) 955 goto out; 956 957 recv_tok.value = p; 958 recv_tok.length = len; 959 status = process_gssapi_token(ssh, &recv_tok); 960 961 /* Start again with the next method in the list */ 962 if (GSS_ERROR(status)) { 963 userauth(ssh, NULL); 964 /* ok */ 965 } 966 r = 0; 967 out: 968 free(p); 969 return r; 970 } 971 972 /* ARGSUSED */ 973 static int 974 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 975 { 976 Authctxt *authctxt = ssh->authctxt; 977 Gssctxt *gssctxt; 978 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 979 gss_buffer_desc recv_tok; 980 OM_uint32 ms; 981 u_char *p = NULL; 982 size_t len; 983 int r; 984 985 if (authctxt == NULL) 986 fatal("input_gssapi_response: no authentication context"); 987 gssctxt = authctxt->methoddata; 988 989 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 990 (r = sshpkt_get_end(ssh)) != 0) { 991 free(p); 992 return r; 993 } 994 995 /* Stick it into GSSAPI and see what it says */ 996 recv_tok.value = p; 997 recv_tok.length = len; 998 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 999 &recv_tok, &send_tok, NULL); 1000 free(p); 1001 gss_release_buffer(&ms, &send_tok); 1002 1003 /* Server will be returning a failed packet after this one */ 1004 return 0; 1005 } 1006 1007 /* ARGSUSED */ 1008 static int 1009 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1010 { 1011 char *msg = NULL; 1012 char *lang = NULL; 1013 int r; 1014 1015 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1016 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1017 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1018 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1019 goto out; 1020 r = sshpkt_get_end(ssh); 1021 debug("Server GSSAPI Error:\n%s", msg); 1022 out: 1023 free(msg); 1024 free(lang); 1025 return r; 1026 } 1027 #endif /* GSSAPI */ 1028 1029 static int 1030 userauth_none(struct ssh *ssh) 1031 { 1032 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1033 int r; 1034 1035 /* initial userauth request */ 1036 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1037 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1038 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1039 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1040 (r = sshpkt_send(ssh)) != 0) 1041 fatal_fr(r, "send packet"); 1042 return 1; 1043 } 1044 1045 static int 1046 userauth_passwd(struct ssh *ssh) 1047 { 1048 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1049 char *password, *prompt = NULL; 1050 const char *host = options.host_key_alias ? options.host_key_alias : 1051 authctxt->host; 1052 int r; 1053 1054 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1055 return 0; 1056 1057 if (authctxt->attempt_passwd != 1) 1058 error("Permission denied, please try again."); 1059 1060 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1061 password = read_passphrase(prompt, 0); 1062 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1063 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1064 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1065 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1066 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1067 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1068 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1069 (r = sshpkt_send(ssh)) != 0) 1070 fatal_fr(r, "send packet"); 1071 1072 free(prompt); 1073 if (password != NULL) 1074 freezero(password, strlen(password)); 1075 1076 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1077 &input_userauth_passwd_changereq); 1078 1079 return 1; 1080 } 1081 1082 /* 1083 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1084 */ 1085 /* ARGSUSED */ 1086 static int 1087 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1088 { 1089 Authctxt *authctxt = ssh->authctxt; 1090 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1091 char prompt[256]; 1092 const char *host; 1093 int r; 1094 1095 debug2("input_userauth_passwd_changereq"); 1096 1097 if (authctxt == NULL) 1098 fatal("input_userauth_passwd_changereq: " 1099 "no authentication context"); 1100 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1101 1102 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1103 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1104 goto out; 1105 if (strlen(info) > 0) 1106 logit("%s", info); 1107 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1108 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1109 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1110 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1111 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1112 goto out; 1113 1114 snprintf(prompt, sizeof(prompt), 1115 "Enter %.30s@%.128s's old password: ", 1116 authctxt->server_user, host); 1117 password = read_passphrase(prompt, 0); 1118 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1119 goto out; 1120 1121 freezero(password, strlen(password)); 1122 password = NULL; 1123 while (password == NULL) { 1124 snprintf(prompt, sizeof(prompt), 1125 "Enter %.30s@%.128s's new password: ", 1126 authctxt->server_user, host); 1127 password = read_passphrase(prompt, RP_ALLOW_EOF); 1128 if (password == NULL) { 1129 /* bail out */ 1130 r = 0; 1131 goto out; 1132 } 1133 snprintf(prompt, sizeof(prompt), 1134 "Retype %.30s@%.128s's new password: ", 1135 authctxt->server_user, host); 1136 retype = read_passphrase(prompt, 0); 1137 if (strcmp(password, retype) != 0) { 1138 freezero(password, strlen(password)); 1139 logit("Mismatch; try again, EOF to quit."); 1140 password = NULL; 1141 } 1142 freezero(retype, strlen(retype)); 1143 } 1144 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1145 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1146 (r = sshpkt_send(ssh)) != 0) 1147 goto out; 1148 1149 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1150 &input_userauth_passwd_changereq); 1151 r = 0; 1152 out: 1153 if (password) 1154 freezero(password, strlen(password)); 1155 free(info); 1156 free(lang); 1157 return r; 1158 } 1159 1160 /* 1161 * Select an algorithm for publickey signatures. 1162 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1163 * 1164 * Call with ssh==NULL to ignore server-sig-algs extension list and 1165 * only attempt with the key's base signature type. 1166 */ 1167 static char * 1168 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1169 { 1170 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1171 1172 /* 1173 * The signature algorithm will only differ from the key algorithm 1174 * for RSA keys/certs and when the server advertises support for 1175 * newer (SHA2) algorithms. 1176 */ 1177 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1178 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1179 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1180 /* Filter base key signature alg against our configuration */ 1181 return match_list(sshkey_ssh_name(key), 1182 options.pubkey_key_types, NULL); 1183 } 1184 1185 /* 1186 * For RSA keys/certs, since these might have a different sig type: 1187 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1188 * that also appears in the supported signature algorithms list from 1189 * the server. 1190 */ 1191 oallowed = allowed = xstrdup(options.pubkey_key_types); 1192 while ((cp = strsep(&allowed, ",")) != NULL) { 1193 if (sshkey_type_from_name(cp) != key->type) 1194 continue; 1195 tmp = match_list(sshkey_sigalg_by_name(cp), 1196 ssh->kex->server_sig_algs, NULL); 1197 if (tmp != NULL) 1198 alg = xstrdup(cp); 1199 free(tmp); 1200 if (alg != NULL) 1201 break; 1202 } 1203 free(oallowed); 1204 return alg; 1205 } 1206 1207 static int 1208 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1209 const u_char *data, size_t datalen, u_int compat, const char *alg) 1210 { 1211 struct sshkey *sign_key = NULL, *prv = NULL; 1212 int r = SSH_ERR_INTERNAL_ERROR; 1213 struct notifier_ctx *notifier = NULL; 1214 char *fp = NULL, *pin = NULL, *prompt = NULL; 1215 1216 *sigp = NULL; 1217 *lenp = 0; 1218 1219 /* The agent supports this key. */ 1220 if (id->key != NULL && id->agent_fd != -1) { 1221 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1222 data, datalen, alg, compat); 1223 } 1224 1225 /* 1226 * We have already loaded the private key or the private key is 1227 * stored in external hardware. 1228 */ 1229 if (id->key != NULL && 1230 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1231 sign_key = id->key; 1232 } else { 1233 /* Load the private key from the file. */ 1234 if ((prv = load_identity_file(id)) == NULL) 1235 return SSH_ERR_KEY_NOT_FOUND; 1236 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1237 error_f("private key %s contents do not match public", 1238 id->filename); 1239 r = SSH_ERR_KEY_NOT_FOUND; 1240 goto out; 1241 } 1242 sign_key = prv; 1243 if (sshkey_is_sk(sign_key)) { 1244 if ((sign_key->sk_flags & 1245 SSH_SK_USER_VERIFICATION_REQD)) { 1246 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1247 sshkey_type(sign_key), id->filename); 1248 pin = read_passphrase(prompt, 0); 1249 } 1250 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1251 /* XXX should batch mode just skip these? */ 1252 if ((fp = sshkey_fingerprint(sign_key, 1253 options.fingerprint_hash, 1254 SSH_FP_DEFAULT)) == NULL) 1255 fatal_f("fingerprint failed"); 1256 notifier = notify_start(options.batch_mode, 1257 "Confirm user presence for key %s %s", 1258 sshkey_type(sign_key), fp); 1259 free(fp); 1260 } 1261 } 1262 } 1263 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1264 alg, options.sk_provider, pin, compat)) != 0) { 1265 debug_fr(r, "sshkey_sign"); 1266 goto out; 1267 } 1268 /* 1269 * PKCS#11 tokens may not support all signature algorithms, 1270 * so check what we get back. 1271 */ 1272 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1273 debug_fr(r, "sshkey_check_sigtype"); 1274 goto out; 1275 } 1276 /* success */ 1277 r = 0; 1278 out: 1279 free(prompt); 1280 if (pin != NULL) 1281 freezero(pin, strlen(pin)); 1282 notify_complete(notifier); 1283 sshkey_free(prv); 1284 return r; 1285 } 1286 1287 static int 1288 id_filename_matches(Identity *id, Identity *private_id) 1289 { 1290 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1291 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1292 size_t i, slen; 1293 1294 if (strcmp(id->filename, private_id->filename) == 0) 1295 return 1; 1296 for (i = 0; suffixes[i]; i++) { 1297 slen = strlen(suffixes[i]); 1298 if (len > slen && plen == len - slen && 1299 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1300 memcmp(id->filename, private_id->filename, plen) == 0) 1301 return 1; 1302 } 1303 return 0; 1304 } 1305 1306 static int 1307 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1308 { 1309 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1310 struct sshbuf *b = NULL; 1311 Identity *private_id, *sign_id = NULL; 1312 u_char *signature = NULL; 1313 size_t slen = 0, skip = 0; 1314 int r, fallback_sigtype, sent = 0; 1315 char *alg = NULL, *fp = NULL; 1316 const char *loc = ""; 1317 1318 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1319 SSH_FP_DEFAULT)) == NULL) 1320 return 0; 1321 1322 debug3_f("%s %s", sshkey_type(id->key), fp); 1323 1324 /* 1325 * If the key is an certificate, try to find a matching private key 1326 * and use it to complete the signature. 1327 * If no such private key exists, fall back to trying the certificate 1328 * key itself in case it has a private half already loaded. 1329 * This will try to set sign_id to the private key that will perform 1330 * the signature. 1331 */ 1332 if (sshkey_is_cert(id->key)) { 1333 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1334 if (sshkey_equal_public(id->key, private_id->key) && 1335 id->key->type != private_id->key->type) { 1336 sign_id = private_id; 1337 break; 1338 } 1339 } 1340 /* 1341 * Exact key matches are preferred, but also allow 1342 * filename matches for non-PKCS#11/agent keys that 1343 * didn't load public keys. This supports the case 1344 * of keeping just a private key file and public 1345 * certificate on disk. 1346 */ 1347 if (sign_id == NULL && 1348 !id->isprivate && id->agent_fd == -1 && 1349 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1350 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1351 if (private_id->key == NULL && 1352 id_filename_matches(id, private_id)) { 1353 sign_id = private_id; 1354 break; 1355 } 1356 } 1357 } 1358 if (sign_id != NULL) { 1359 debug2_f("using private key \"%s\"%s for " 1360 "certificate", id->filename, 1361 id->agent_fd != -1 ? " from agent" : ""); 1362 } else { 1363 debug_f("no separate private key for certificate " 1364 "\"%s\"", id->filename); 1365 } 1366 } 1367 1368 /* 1369 * If the above didn't select another identity to do the signing 1370 * then default to the one we started with. 1371 */ 1372 if (sign_id == NULL) 1373 sign_id = id; 1374 1375 /* assemble and sign data */ 1376 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1377 free(alg); 1378 slen = 0; 1379 signature = NULL; 1380 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1381 id->key)) == NULL) { 1382 error_f("no mutual signature supported"); 1383 goto out; 1384 } 1385 debug3_f("signing using %s %s", alg, fp); 1386 1387 sshbuf_free(b); 1388 if ((b = sshbuf_new()) == NULL) 1389 fatal_f("sshbuf_new failed"); 1390 if (datafellows & SSH_OLD_SESSIONID) { 1391 if ((r = sshbuf_put(b, session_id2, 1392 session_id2_len)) != 0) 1393 fatal_fr(r, "sshbuf_put"); 1394 } else { 1395 if ((r = sshbuf_put_string(b, session_id2, 1396 session_id2_len)) != 0) 1397 fatal_fr(r, "sshbuf_put_string"); 1398 } 1399 skip = sshbuf_len(b); 1400 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1401 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1402 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1403 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1404 (r = sshbuf_put_u8(b, 1)) != 0 || 1405 (r = sshbuf_put_cstring(b, alg)) != 0 || 1406 (r = sshkey_puts(id->key, b)) != 0) { 1407 fatal_fr(r, "assemble signed data"); 1408 } 1409 1410 /* generate signature */ 1411 r = identity_sign(sign_id, &signature, &slen, 1412 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1413 if (r == 0) 1414 break; 1415 else if (r == SSH_ERR_KEY_NOT_FOUND) 1416 goto out; /* soft failure */ 1417 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1418 !fallback_sigtype) { 1419 if (sign_id->agent_fd != -1) 1420 loc = "agent "; 1421 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1422 loc = "token "; 1423 logit("%skey %s %s returned incorrect signature type", 1424 loc, sshkey_type(id->key), fp); 1425 continue; 1426 } 1427 error_fr(r, "signing failed for %s \"%s\"%s", 1428 sshkey_type(sign_id->key), sign_id->filename, 1429 id->agent_fd != -1 ? " from agent" : ""); 1430 goto out; 1431 } 1432 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1433 fatal_f("no signature"); 1434 1435 /* append signature */ 1436 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1437 fatal_fr(r, "append signature"); 1438 1439 #ifdef DEBUG_PK 1440 sshbuf_dump(b, stderr); 1441 #endif 1442 /* skip session id and packet type */ 1443 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1444 fatal_fr(r, "consume"); 1445 1446 /* put remaining data from buffer into packet */ 1447 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1448 (r = sshpkt_putb(ssh, b)) != 0 || 1449 (r = sshpkt_send(ssh)) != 0) 1450 fatal_fr(r, "enqueue request"); 1451 1452 /* success */ 1453 sent = 1; 1454 1455 out: 1456 free(fp); 1457 free(alg); 1458 sshbuf_free(b); 1459 freezero(signature, slen); 1460 return sent; 1461 } 1462 1463 static int 1464 send_pubkey_test(struct ssh *ssh, Identity *id) 1465 { 1466 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1467 u_char *blob = NULL; 1468 char *alg = NULL; 1469 size_t bloblen; 1470 u_int have_sig = 0; 1471 int sent = 0, r; 1472 1473 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1474 debug_f("no mutual signature algorithm"); 1475 goto out; 1476 } 1477 1478 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1479 /* we cannot handle this key */ 1480 debug3_f("cannot handle key"); 1481 goto out; 1482 } 1483 /* register callback for USERAUTH_PK_OK message */ 1484 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1485 1486 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1487 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1488 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1489 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1490 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1491 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1492 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1493 (r = sshpkt_send(ssh)) != 0) 1494 fatal_fr(r, "send packet"); 1495 sent = 1; 1496 1497 out: 1498 free(alg); 1499 free(blob); 1500 return sent; 1501 } 1502 1503 static struct sshkey * 1504 load_identity_file(Identity *id) 1505 { 1506 struct sshkey *private = NULL; 1507 char prompt[300], *passphrase, *comment; 1508 int r, quit = 0, i; 1509 struct stat st; 1510 1511 if (stat(id->filename, &st) == -1) { 1512 do_log2(id->userprovided ? 1513 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1514 "no such identity: %s: %s", id->filename, strerror(errno)); 1515 return NULL; 1516 } 1517 snprintf(prompt, sizeof prompt, 1518 "Enter passphrase for key '%.100s': ", id->filename); 1519 for (i = 0; i <= options.number_of_password_prompts; i++) { 1520 if (i == 0) 1521 passphrase = ""; 1522 else { 1523 passphrase = read_passphrase(prompt, 0); 1524 if (*passphrase == '\0') { 1525 debug2("no passphrase given, try next key"); 1526 free(passphrase); 1527 break; 1528 } 1529 } 1530 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1531 passphrase, &private, &comment))) { 1532 case 0: 1533 break; 1534 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1535 if (options.batch_mode) { 1536 quit = 1; 1537 break; 1538 } 1539 if (i != 0) 1540 debug2("bad passphrase given, try again..."); 1541 break; 1542 case SSH_ERR_SYSTEM_ERROR: 1543 if (errno == ENOENT) { 1544 debug2_r(r, "Load key \"%s\"", id->filename); 1545 quit = 1; 1546 break; 1547 } 1548 /* FALLTHROUGH */ 1549 default: 1550 error_r(r, "Load key \"%s\"", id->filename); 1551 quit = 1; 1552 break; 1553 } 1554 if (private != NULL && sshkey_is_sk(private) && 1555 options.sk_provider == NULL) { 1556 debug("key \"%s\" is an authenticator-hosted key, " 1557 "but no provider specified", id->filename); 1558 sshkey_free(private); 1559 private = NULL; 1560 quit = 1; 1561 } 1562 if (!quit && private != NULL && id->agent_fd == -1 && 1563 !(id->key && id->isprivate)) 1564 maybe_add_key_to_agent(id->filename, private, comment, 1565 passphrase); 1566 if (i > 0) 1567 freezero(passphrase, strlen(passphrase)); 1568 free(comment); 1569 if (private != NULL || quit) 1570 break; 1571 } 1572 return private; 1573 } 1574 1575 static int 1576 key_type_allowed_by_config(struct sshkey *key) 1577 { 1578 if (match_pattern_list(sshkey_ssh_name(key), 1579 options.pubkey_key_types, 0) == 1) 1580 return 1; 1581 1582 /* RSA keys/certs might be allowed by alternate signature types */ 1583 switch (key->type) { 1584 case KEY_RSA: 1585 if (match_pattern_list("rsa-sha2-512", 1586 options.pubkey_key_types, 0) == 1) 1587 return 1; 1588 if (match_pattern_list("rsa-sha2-256", 1589 options.pubkey_key_types, 0) == 1) 1590 return 1; 1591 break; 1592 case KEY_RSA_CERT: 1593 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1594 options.pubkey_key_types, 0) == 1) 1595 return 1; 1596 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1597 options.pubkey_key_types, 0) == 1) 1598 return 1; 1599 break; 1600 } 1601 return 0; 1602 } 1603 1604 1605 /* 1606 * try keys in the following order: 1607 * 1. certificates listed in the config file 1608 * 2. other input certificates 1609 * 3. agent keys that are found in the config file 1610 * 4. other agent keys 1611 * 5. keys that are only listed in the config file 1612 */ 1613 static void 1614 pubkey_prepare(Authctxt *authctxt) 1615 { 1616 struct identity *id, *id2, *tmp; 1617 struct idlist agent, files, *preferred; 1618 struct sshkey *key; 1619 int agent_fd = -1, i, r, found; 1620 size_t j; 1621 struct ssh_identitylist *idlist; 1622 char *ident; 1623 1624 TAILQ_INIT(&agent); /* keys from the agent */ 1625 TAILQ_INIT(&files); /* keys from the config file */ 1626 preferred = &authctxt->keys; 1627 TAILQ_INIT(preferred); /* preferred order of keys */ 1628 1629 /* list of keys stored in the filesystem and PKCS#11 */ 1630 for (i = 0; i < options.num_identity_files; i++) { 1631 key = options.identity_keys[i]; 1632 if (key && key->cert && 1633 key->cert->type != SSH2_CERT_TYPE_USER) { 1634 debug_f("ignoring certificate %s: not a user " 1635 "certificate", options.identity_files[i]); 1636 continue; 1637 } 1638 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1639 debug_f("ignoring authenticator-hosted key %s as no " 1640 "SecurityKeyProvider has been specified", 1641 options.identity_files[i]); 1642 continue; 1643 } 1644 options.identity_keys[i] = NULL; 1645 id = xcalloc(1, sizeof(*id)); 1646 id->agent_fd = -1; 1647 id->key = key; 1648 id->filename = xstrdup(options.identity_files[i]); 1649 id->userprovided = options.identity_file_userprovided[i]; 1650 TAILQ_INSERT_TAIL(&files, id, next); 1651 } 1652 /* list of certificates specified by user */ 1653 for (i = 0; i < options.num_certificate_files; i++) { 1654 key = options.certificates[i]; 1655 if (!sshkey_is_cert(key) || key->cert == NULL || 1656 key->cert->type != SSH2_CERT_TYPE_USER) { 1657 debug_f("ignoring certificate %s: not a user " 1658 "certificate", options.identity_files[i]); 1659 continue; 1660 } 1661 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1662 debug_f("ignoring authenticator-hosted key " 1663 "certificate %s as no " 1664 "SecurityKeyProvider has been specified", 1665 options.identity_files[i]); 1666 continue; 1667 } 1668 id = xcalloc(1, sizeof(*id)); 1669 id->agent_fd = -1; 1670 id->key = key; 1671 id->filename = xstrdup(options.certificate_files[i]); 1672 id->userprovided = options.certificate_file_userprovided[i]; 1673 TAILQ_INSERT_TAIL(preferred, id, next); 1674 } 1675 /* list of keys supported by the agent */ 1676 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1677 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1678 debug_fr(r, "ssh_get_authentication_socket"); 1679 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1680 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1681 debug_fr(r, "ssh_fetch_identitylist"); 1682 close(agent_fd); 1683 } else { 1684 for (j = 0; j < idlist->nkeys; j++) { 1685 found = 0; 1686 TAILQ_FOREACH(id, &files, next) { 1687 /* 1688 * agent keys from the config file are 1689 * preferred 1690 */ 1691 if (sshkey_equal(idlist->keys[j], id->key)) { 1692 TAILQ_REMOVE(&files, id, next); 1693 TAILQ_INSERT_TAIL(preferred, id, next); 1694 id->agent_fd = agent_fd; 1695 found = 1; 1696 break; 1697 } 1698 } 1699 if (!found && !options.identities_only) { 1700 id = xcalloc(1, sizeof(*id)); 1701 /* XXX "steals" key/comment from idlist */ 1702 id->key = idlist->keys[j]; 1703 id->filename = idlist->comments[j]; 1704 idlist->keys[j] = NULL; 1705 idlist->comments[j] = NULL; 1706 id->agent_fd = agent_fd; 1707 TAILQ_INSERT_TAIL(&agent, id, next); 1708 } 1709 } 1710 ssh_free_identitylist(idlist); 1711 /* append remaining agent keys */ 1712 TAILQ_CONCAT(preferred, &agent, next); 1713 authctxt->agent_fd = agent_fd; 1714 } 1715 /* Prefer PKCS11 keys that are explicitly listed */ 1716 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1717 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1718 continue; 1719 found = 0; 1720 TAILQ_FOREACH(id2, &files, next) { 1721 if (id2->key == NULL || 1722 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1723 continue; 1724 if (sshkey_equal(id->key, id2->key)) { 1725 TAILQ_REMOVE(&files, id, next); 1726 TAILQ_INSERT_TAIL(preferred, id, next); 1727 found = 1; 1728 break; 1729 } 1730 } 1731 /* If IdentitiesOnly set and key not found then don't use it */ 1732 if (!found && options.identities_only) { 1733 TAILQ_REMOVE(&files, id, next); 1734 freezero(id, sizeof(*id)); 1735 } 1736 } 1737 /* append remaining keys from the config file */ 1738 TAILQ_CONCAT(preferred, &files, next); 1739 /* finally, filter by PubkeyAcceptedKeyTypes */ 1740 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1741 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1742 debug("Skipping %s key %s - " 1743 "not in PubkeyAcceptedKeyTypes", 1744 sshkey_ssh_name(id->key), id->filename); 1745 TAILQ_REMOVE(preferred, id, next); 1746 sshkey_free(id->key); 1747 free(id->filename); 1748 memset(id, 0, sizeof(*id)); 1749 continue; 1750 } 1751 } 1752 /* List the keys we plan on using */ 1753 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1754 ident = format_identity(id); 1755 debug("Will attempt key: %s", ident); 1756 free(ident); 1757 } 1758 debug2_f("done"); 1759 } 1760 1761 static void 1762 pubkey_cleanup(struct ssh *ssh) 1763 { 1764 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1765 Identity *id; 1766 1767 if (authctxt->agent_fd != -1) { 1768 ssh_close_authentication_socket(authctxt->agent_fd); 1769 authctxt->agent_fd = -1; 1770 } 1771 for (id = TAILQ_FIRST(&authctxt->keys); id; 1772 id = TAILQ_FIRST(&authctxt->keys)) { 1773 TAILQ_REMOVE(&authctxt->keys, id, next); 1774 sshkey_free(id->key); 1775 free(id->filename); 1776 free(id); 1777 } 1778 } 1779 1780 static void 1781 pubkey_reset(Authctxt *authctxt) 1782 { 1783 Identity *id; 1784 1785 TAILQ_FOREACH(id, &authctxt->keys, next) 1786 id->tried = 0; 1787 } 1788 1789 static int 1790 try_identity(Identity *id) 1791 { 1792 if (!id->key) 1793 return (0); 1794 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1795 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1796 debug("Skipped %s key %s for RSA/MD5 server", 1797 sshkey_type(id->key), id->filename); 1798 return (0); 1799 } 1800 return 1; 1801 } 1802 1803 static int 1804 userauth_pubkey(struct ssh *ssh) 1805 { 1806 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1807 Identity *id; 1808 int sent = 0; 1809 char *ident; 1810 1811 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1812 if (id->tried++) 1813 return (0); 1814 /* move key to the end of the queue */ 1815 TAILQ_REMOVE(&authctxt->keys, id, next); 1816 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1817 /* 1818 * send a test message if we have the public key. for 1819 * encrypted keys we cannot do this and have to load the 1820 * private key instead 1821 */ 1822 if (id->key != NULL) { 1823 if (try_identity(id)) { 1824 ident = format_identity(id); 1825 debug("Offering public key: %s", ident); 1826 free(ident); 1827 sent = send_pubkey_test(ssh, id); 1828 } 1829 } else { 1830 debug("Trying private key: %s", id->filename); 1831 id->key = load_identity_file(id); 1832 if (id->key != NULL) { 1833 if (try_identity(id)) { 1834 id->isprivate = 1; 1835 sent = sign_and_send_pubkey(ssh, id); 1836 } 1837 sshkey_free(id->key); 1838 id->key = NULL; 1839 id->isprivate = 0; 1840 } 1841 } 1842 if (sent) 1843 return (sent); 1844 } 1845 return (0); 1846 } 1847 1848 /* 1849 * Send userauth request message specifying keyboard-interactive method. 1850 */ 1851 static int 1852 userauth_kbdint(struct ssh *ssh) 1853 { 1854 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1855 int r; 1856 1857 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1858 return 0; 1859 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1860 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1861 debug3("userauth_kbdint: disable: no info_req_seen"); 1862 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1863 return 0; 1864 } 1865 1866 debug2("userauth_kbdint"); 1867 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1868 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1869 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1870 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1871 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1872 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1873 options.kbd_interactive_devices : "")) != 0 || 1874 (r = sshpkt_send(ssh)) != 0) 1875 fatal_fr(r, "send packet"); 1876 1877 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1878 return 1; 1879 } 1880 1881 /* 1882 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1883 */ 1884 static int 1885 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1886 { 1887 Authctxt *authctxt = ssh->authctxt; 1888 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1889 char *response = NULL; 1890 u_char echo = 0; 1891 u_int num_prompts, i; 1892 int r; 1893 1894 debug2("input_userauth_info_req"); 1895 1896 if (authctxt == NULL) 1897 fatal("input_userauth_info_req: no authentication context"); 1898 1899 authctxt->info_req_seen = 1; 1900 1901 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1902 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1903 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1904 goto out; 1905 if (strlen(name) > 0) 1906 logit("%s", name); 1907 if (strlen(inst) > 0) 1908 logit("%s", inst); 1909 1910 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1911 goto out; 1912 /* 1913 * Begin to build info response packet based on prompts requested. 1914 * We commit to providing the correct number of responses, so if 1915 * further on we run into a problem that prevents this, we have to 1916 * be sure and clean this up and send a correct error response. 1917 */ 1918 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1919 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1920 goto out; 1921 1922 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1923 for (i = 0; i < num_prompts; i++) { 1924 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1925 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1926 goto out; 1927 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1928 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1929 goto out; 1930 freezero(response, strlen(response)); 1931 free(prompt); 1932 response = prompt = NULL; 1933 } 1934 /* done with parsing incoming message. */ 1935 if ((r = sshpkt_get_end(ssh)) != 0 || 1936 (r = sshpkt_add_padding(ssh, 64)) != 0) 1937 goto out; 1938 r = sshpkt_send(ssh); 1939 out: 1940 if (response) 1941 freezero(response, strlen(response)); 1942 free(prompt); 1943 free(name); 1944 free(inst); 1945 free(lang); 1946 return r; 1947 } 1948 1949 static int 1950 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1951 const u_char *data, size_t datalen) 1952 { 1953 struct sshbuf *b; 1954 struct stat st; 1955 pid_t pid; 1956 int r, to[2], from[2], status; 1957 int sock = ssh_packet_get_connection_in(ssh); 1958 u_char rversion = 0, version = 2; 1959 void (*osigchld)(int); 1960 1961 *sigp = NULL; 1962 *lenp = 0; 1963 1964 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1965 error_f("not installed: %s", strerror(errno)); 1966 return -1; 1967 } 1968 if (fflush(stdout) != 0) { 1969 error_f("fflush: %s", strerror(errno)); 1970 return -1; 1971 } 1972 if (pipe(to) == -1) { 1973 error_f("pipe: %s", strerror(errno)); 1974 return -1; 1975 } 1976 if (pipe(from) == -1) { 1977 error_f("pipe: %s", strerror(errno)); 1978 return -1; 1979 } 1980 if ((pid = fork()) == -1) { 1981 error_f("fork: %s", strerror(errno)); 1982 return -1; 1983 } 1984 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1985 if (pid == 0) { 1986 close(from[0]); 1987 if (dup2(from[1], STDOUT_FILENO) == -1) 1988 fatal_f("dup2: %s", strerror(errno)); 1989 close(to[1]); 1990 if (dup2(to[0], STDIN_FILENO) == -1) 1991 fatal_f("dup2: %s", strerror(errno)); 1992 close(from[1]); 1993 close(to[0]); 1994 1995 if (dup2(sock, STDERR_FILENO + 1) == -1) 1996 fatal_f("dup2: %s", strerror(errno)); 1997 sock = STDERR_FILENO + 1; 1998 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 1999 closefrom(sock + 1); 2000 2001 debug3_f("[child] pid=%ld, exec %s", 2002 (long)getpid(), _PATH_SSH_KEY_SIGN); 2003 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2004 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2005 strerror(errno)); 2006 } 2007 close(from[1]); 2008 close(to[0]); 2009 sock = STDERR_FILENO + 1; 2010 2011 if ((b = sshbuf_new()) == NULL) 2012 fatal_f("sshbuf_new failed"); 2013 /* send # of sock, data to be signed */ 2014 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2015 (r = sshbuf_put_string(b, data, datalen)) != 0) 2016 fatal_fr(r, "buffer error"); 2017 if (ssh_msg_send(to[1], version, b) == -1) 2018 fatal_f("couldn't send request"); 2019 sshbuf_reset(b); 2020 r = ssh_msg_recv(from[0], b); 2021 close(from[0]); 2022 close(to[1]); 2023 if (r < 0) { 2024 error_f("no reply"); 2025 goto fail; 2026 } 2027 2028 errno = 0; 2029 while (waitpid(pid, &status, 0) == -1) { 2030 if (errno != EINTR) { 2031 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2032 goto fail; 2033 } 2034 } 2035 if (!WIFEXITED(status)) { 2036 error_f("exited abnormally"); 2037 goto fail; 2038 } 2039 if (WEXITSTATUS(status) != 0) { 2040 error_f("exited with status %d", WEXITSTATUS(status)); 2041 goto fail; 2042 } 2043 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2044 error_fr(r, "buffer error"); 2045 goto fail; 2046 } 2047 if (rversion != version) { 2048 error_f("bad version"); 2049 goto fail; 2050 } 2051 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2052 error_fr(r, "buffer error"); 2053 fail: 2054 ssh_signal(SIGCHLD, osigchld); 2055 sshbuf_free(b); 2056 return -1; 2057 } 2058 ssh_signal(SIGCHLD, osigchld); 2059 sshbuf_free(b); 2060 2061 return 0; 2062 } 2063 2064 static int 2065 userauth_hostbased(struct ssh *ssh) 2066 { 2067 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2068 struct sshkey *private = NULL; 2069 struct sshbuf *b = NULL; 2070 u_char *sig = NULL, *keyblob = NULL; 2071 char *fp = NULL, *chost = NULL, *lname = NULL; 2072 size_t siglen = 0, keylen = 0; 2073 int i, r, success = 0; 2074 2075 if (authctxt->ktypes == NULL) { 2076 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2077 authctxt->ktypes = authctxt->oktypes; 2078 } 2079 2080 /* 2081 * Work through each listed type pattern in HostbasedKeyTypes, 2082 * trying each hostkey that matches the type in turn. 2083 */ 2084 for (;;) { 2085 if (authctxt->active_ktype == NULL) 2086 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2087 if (authctxt->active_ktype == NULL || 2088 *authctxt->active_ktype == '\0') 2089 break; 2090 debug3_f("trying key type %s", authctxt->active_ktype); 2091 2092 /* check for a useful key */ 2093 private = NULL; 2094 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2095 if (authctxt->sensitive->keys[i] == NULL || 2096 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2097 continue; 2098 if (match_pattern_list( 2099 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2100 authctxt->active_ktype, 0) != 1) 2101 continue; 2102 /* we take and free the key */ 2103 private = authctxt->sensitive->keys[i]; 2104 authctxt->sensitive->keys[i] = NULL; 2105 break; 2106 } 2107 /* Found one */ 2108 if (private != NULL) 2109 break; 2110 /* No more keys of this type; advance */ 2111 authctxt->active_ktype = NULL; 2112 } 2113 if (private == NULL) { 2114 free(authctxt->oktypes); 2115 authctxt->oktypes = authctxt->ktypes = NULL; 2116 authctxt->active_ktype = NULL; 2117 debug("No more client hostkeys for hostbased authentication."); 2118 goto out; 2119 } 2120 2121 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2122 SSH_FP_DEFAULT)) == NULL) { 2123 error_f("sshkey_fingerprint failed"); 2124 goto out; 2125 } 2126 debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp); 2127 2128 /* figure out a name for the client host */ 2129 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2130 if (lname == NULL) { 2131 error_f("cannot get local ipaddr/name"); 2132 goto out; 2133 } 2134 2135 /* XXX sshbuf_put_stringf? */ 2136 xasprintf(&chost, "%s.", lname); 2137 debug2_f("chost %s", chost); 2138 2139 /* construct data */ 2140 if ((b = sshbuf_new()) == NULL) { 2141 error_f("sshbuf_new failed"); 2142 goto out; 2143 } 2144 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2145 error_fr(r, "sshkey_to_blob"); 2146 goto out; 2147 } 2148 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2149 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2150 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2151 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2152 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2153 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2154 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2155 (r = sshbuf_put_cstring(b, chost)) != 0 || 2156 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2157 error_fr(r, "buffer error"); 2158 goto out; 2159 } 2160 2161 #ifdef DEBUG_PK 2162 sshbuf_dump(b, stderr); 2163 #endif 2164 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2165 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2166 error("sign using hostkey %s %s failed", 2167 sshkey_ssh_name(private), fp); 2168 goto out; 2169 } 2170 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2171 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2172 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2173 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2174 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2175 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2176 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2177 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2178 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2179 (r = sshpkt_send(ssh)) != 0) { 2180 error_fr(r, "packet error"); 2181 goto out; 2182 } 2183 success = 1; 2184 2185 out: 2186 if (sig != NULL) 2187 freezero(sig, siglen); 2188 free(keyblob); 2189 free(lname); 2190 free(fp); 2191 free(chost); 2192 sshkey_free(private); 2193 sshbuf_free(b); 2194 2195 return success; 2196 } 2197 2198 /* find auth method */ 2199 2200 /* 2201 * given auth method name, if configurable options permit this method fill 2202 * in auth_ident field and return true, otherwise return false. 2203 */ 2204 static int 2205 authmethod_is_enabled(Authmethod *method) 2206 { 2207 if (method == NULL) 2208 return 0; 2209 /* return false if options indicate this method is disabled */ 2210 if (method->enabled == NULL || *method->enabled == 0) 2211 return 0; 2212 /* return false if batch mode is enabled but method needs interactive mode */ 2213 if (method->batch_flag != NULL && *method->batch_flag != 0) 2214 return 0; 2215 return 1; 2216 } 2217 2218 static Authmethod * 2219 authmethod_lookup(const char *name) 2220 { 2221 Authmethod *method = NULL; 2222 if (name != NULL) 2223 for (method = authmethods; method->name != NULL; method++) 2224 if (strcmp(name, method->name) == 0) 2225 return method; 2226 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2227 return NULL; 2228 } 2229 2230 /* XXX internal state */ 2231 static Authmethod *current = NULL; 2232 static char *supported = NULL; 2233 static char *preferred = NULL; 2234 2235 /* 2236 * Given the authentication method list sent by the server, return the 2237 * next method we should try. If the server initially sends a nil list, 2238 * use a built-in default list. 2239 */ 2240 static Authmethod * 2241 authmethod_get(char *authlist) 2242 { 2243 char *name = NULL; 2244 u_int next; 2245 2246 /* Use a suitable default if we're passed a nil list. */ 2247 if (authlist == NULL || strlen(authlist) == 0) 2248 authlist = options.preferred_authentications; 2249 2250 if (supported == NULL || strcmp(authlist, supported) != 0) { 2251 debug3("start over, passed a different list %s", authlist); 2252 free(supported); 2253 supported = xstrdup(authlist); 2254 preferred = options.preferred_authentications; 2255 debug3("preferred %s", preferred); 2256 current = NULL; 2257 } else if (current != NULL && authmethod_is_enabled(current)) 2258 return current; 2259 2260 for (;;) { 2261 if ((name = match_list(preferred, supported, &next)) == NULL) { 2262 debug("No more authentication methods to try."); 2263 current = NULL; 2264 return NULL; 2265 } 2266 preferred += next; 2267 debug3("authmethod_lookup %s", name); 2268 debug3("remaining preferred: %s", preferred); 2269 if ((current = authmethod_lookup(name)) != NULL && 2270 authmethod_is_enabled(current)) { 2271 debug3("authmethod_is_enabled %s", name); 2272 debug("Next authentication method: %s", name); 2273 free(name); 2274 return current; 2275 } 2276 free(name); 2277 } 2278 } 2279 2280 static char * 2281 authmethods_get(void) 2282 { 2283 Authmethod *method = NULL; 2284 struct sshbuf *b; 2285 char *list; 2286 int r; 2287 2288 if ((b = sshbuf_new()) == NULL) 2289 fatal_f("sshbuf_new failed"); 2290 for (method = authmethods; method->name != NULL; method++) { 2291 if (authmethod_is_enabled(method)) { 2292 if ((r = sshbuf_putf(b, "%s%s", 2293 sshbuf_len(b) ? "," : "", method->name)) != 0) 2294 fatal_fr(r, "buffer error"); 2295 } 2296 } 2297 if ((list = sshbuf_dup_string(b)) == NULL) 2298 fatal_f("sshbuf_dup_string failed"); 2299 sshbuf_free(b); 2300 return list; 2301 } 2302