1 /* $OpenBSD: sshconnect2.c,v 1.356 2022/02/01 23:32:51 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 static char *xxx_host; 93 static struct sockaddr *xxx_hostaddr; 94 static const struct ssh_conn_info *xxx_conn_info; 95 96 static int 97 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 98 { 99 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 100 xxx_conn_info) == -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 const struct ssh_conn_info *cinfo) 120 { 121 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 122 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 123 size_t maxlen; 124 struct hostkeys *hostkeys = NULL; 125 int ktype; 126 u_int i; 127 128 /* Find all hostkeys for this hostname */ 129 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 130 hostkeys = init_hostkeys(); 131 for (i = 0; i < options.num_user_hostfiles; i++) 132 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 133 for (i = 0; i < options.num_system_hostfiles; i++) { 134 load_hostkeys(hostkeys, hostname, 135 options.system_hostfiles[i], 0); 136 } 137 if (options.known_hosts_command != NULL) { 138 load_hostkeys_command(hostkeys, options.known_hosts_command, 139 "ORDER", cinfo, NULL, host); 140 } 141 /* 142 * If a plain public key exists that matches the type of the best 143 * preference HostkeyAlgorithms, then use the whole list as is. 144 * Note that we ignore whether the best preference algorithm is a 145 * certificate type, as sshconnect.c will downgrade certs to 146 * plain keys if necessary. 147 */ 148 best = first_alg(options.hostkeyalgorithms); 149 if (lookup_key_in_hostkeys_by_type(hostkeys, 150 sshkey_type_plain(sshkey_type_from_name(best)), 151 sshkey_ecdsa_nid_from_name(best), NULL)) { 152 debug3_f("have matching best-preference key type %s, " 153 "using HostkeyAlgorithms verbatim", best); 154 ret = xstrdup(options.hostkeyalgorithms); 155 goto out; 156 } 157 158 /* 159 * Otherwise, prefer the host key algorithms that match known keys 160 * while keeping the ordering of HostkeyAlgorithms as much as possible. 161 */ 162 oavail = avail = xstrdup(options.hostkeyalgorithms); 163 maxlen = strlen(avail) + 1; 164 first = xmalloc(maxlen); 165 last = xmalloc(maxlen); 166 *first = *last = '\0'; 167 168 #define ALG_APPEND(to, from) \ 169 do { \ 170 if (*to != '\0') \ 171 strlcat(to, ",", maxlen); \ 172 strlcat(to, from, maxlen); \ 173 } while (0) 174 175 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 176 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 177 fatal_f("unknown alg %s", alg); 178 /* 179 * If we have a @cert-authority marker in known_hosts then 180 * prefer all certificate algorithms. 181 */ 182 if (sshkey_type_is_cert(ktype) && 183 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 184 ALG_APPEND(first, alg); 185 continue; 186 } 187 /* If the key appears in known_hosts then prefer it */ 188 if (lookup_key_in_hostkeys_by_type(hostkeys, 189 sshkey_type_plain(ktype), 190 sshkey_ecdsa_nid_from_name(alg), NULL)) { 191 ALG_APPEND(first, alg); 192 continue; 193 } 194 /* Otherwise, put it last */ 195 ALG_APPEND(last, alg); 196 } 197 #undef ALG_APPEND 198 xasprintf(&ret, "%s%s%s", first, 199 (*first == '\0' || *last == '\0') ? "" : ",", last); 200 if (*first != '\0') 201 debug3_f("prefer hostkeyalgs: %s", first); 202 else 203 debug3_f("no algorithms matched; accept original"); 204 out: 205 free(best); 206 free(first); 207 free(last); 208 free(hostname); 209 free(oavail); 210 free_hostkeys(hostkeys); 211 212 return ret; 213 } 214 215 void 216 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 217 const struct ssh_conn_info *cinfo) 218 { 219 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 220 char *s, *all_key; 221 int r, use_known_hosts_order = 0; 222 223 xxx_host = host; 224 xxx_hostaddr = hostaddr; 225 xxx_conn_info = cinfo; 226 227 /* 228 * If the user has not specified HostkeyAlgorithms, or has only 229 * appended or removed algorithms from that list then prefer algorithms 230 * that are in the list that are supported by known_hosts keys. 231 */ 232 if (options.hostkeyalgorithms == NULL || 233 options.hostkeyalgorithms[0] == '-' || 234 options.hostkeyalgorithms[0] == '+') 235 use_known_hosts_order = 1; 236 237 /* Expand or fill in HostkeyAlgorithms */ 238 all_key = sshkey_alg_list(0, 0, 1, ','); 239 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 240 kex_default_pk_alg(), all_key)) != 0) 241 fatal_fr(r, "kex_assemble_namelist"); 242 free(all_key); 243 244 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 245 fatal_f("kex_names_cat"); 246 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, s); 247 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 248 compat_cipher_proposal(ssh, options.ciphers); 249 myproposal[PROPOSAL_ENC_ALGS_STOC] = 250 compat_cipher_proposal(ssh, options.ciphers); 251 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 252 myproposal[PROPOSAL_COMP_ALGS_STOC] = 253 (char *)compression_alg_list(options.compression); 254 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 255 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 256 if (use_known_hosts_order) { 257 /* Query known_hosts and prefer algorithms that appear there */ 258 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 259 compat_pkalg_proposal(ssh, 260 order_hostkeyalgs(host, hostaddr, port, cinfo)); 261 } else { 262 /* Use specified HostkeyAlgorithms exactly */ 263 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 264 compat_pkalg_proposal(ssh, options.hostkeyalgorithms); 265 } 266 267 if (options.rekey_limit || options.rekey_interval) 268 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 269 options.rekey_interval); 270 271 /* start key exchange */ 272 if ((r = kex_setup(ssh, myproposal)) != 0) 273 fatal_r(r, "kex_setup"); 274 #ifdef WITH_OPENSSL 275 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 276 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 277 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 278 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 279 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 280 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 281 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 282 # ifdef OPENSSL_HAS_ECC 283 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 284 # endif 285 #endif 286 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 287 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 288 ssh->kex->verify_host_key=&verify_host_key_callback; 289 290 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 291 292 /* remove ext-info from the KEX proposals for rekeying */ 293 myproposal[PROPOSAL_KEX_ALGS] = 294 compat_kex_proposal(ssh, options.kex_algorithms); 295 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 296 fatal_r(r, "kex_prop2buf"); 297 298 #ifdef DEBUG_KEXDH 299 /* send 1st encrypted/maced/compressed message */ 300 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 301 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 302 (r = sshpkt_send(ssh)) != 0 || 303 (r = ssh_packet_write_wait(ssh)) != 0) 304 fatal_fr(r, "send packet"); 305 #endif 306 } 307 308 /* 309 * Authenticate user 310 */ 311 312 typedef struct cauthctxt Authctxt; 313 typedef struct cauthmethod Authmethod; 314 typedef struct identity Identity; 315 typedef struct idlist Idlist; 316 317 struct identity { 318 TAILQ_ENTRY(identity) next; 319 int agent_fd; /* >=0 if agent supports key */ 320 struct sshkey *key; /* public/private key */ 321 char *filename; /* comment for agent-only keys */ 322 int tried; 323 int isprivate; /* key points to the private key */ 324 int userprovided; 325 }; 326 TAILQ_HEAD(idlist, identity); 327 328 struct cauthctxt { 329 const char *server_user; 330 const char *local_user; 331 const char *host; 332 const char *service; 333 struct cauthmethod *method; 334 sig_atomic_t success; 335 char *authlist; 336 #ifdef GSSAPI 337 /* gssapi */ 338 gss_OID_set gss_supported_mechs; 339 u_int mech_tried; 340 #endif 341 /* pubkey */ 342 struct idlist keys; 343 int agent_fd; 344 /* hostbased */ 345 Sensitive *sensitive; 346 char *oktypes, *ktypes; 347 const char *active_ktype; 348 /* kbd-interactive */ 349 int info_req_seen; 350 int attempt_kbdint; 351 /* password */ 352 int attempt_passwd; 353 /* generic */ 354 void *methoddata; 355 }; 356 357 struct cauthmethod { 358 char *name; /* string to compare against server's list */ 359 int (*userauth)(struct ssh *ssh); 360 void (*cleanup)(struct ssh *ssh); 361 int *enabled; /* flag in option struct that enables method */ 362 int *batch_flag; /* flag in option struct that disables method */ 363 }; 364 365 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 366 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 367 static int input_userauth_success(int, u_int32_t, struct ssh *); 368 static int input_userauth_failure(int, u_int32_t, struct ssh *); 369 static int input_userauth_banner(int, u_int32_t, struct ssh *); 370 static int input_userauth_error(int, u_int32_t, struct ssh *); 371 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 372 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 373 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 374 375 static int userauth_none(struct ssh *); 376 static int userauth_pubkey(struct ssh *); 377 static int userauth_passwd(struct ssh *); 378 static int userauth_kbdint(struct ssh *); 379 static int userauth_hostbased(struct ssh *); 380 381 #ifdef GSSAPI 382 static int userauth_gssapi(struct ssh *); 383 static void userauth_gssapi_cleanup(struct ssh *); 384 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 385 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 386 static int input_gssapi_error(int, u_int32_t, struct ssh *); 387 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 388 #endif 389 390 void userauth(struct ssh *, char *); 391 392 static void pubkey_cleanup(struct ssh *); 393 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 394 static void pubkey_prepare(struct ssh *, Authctxt *); 395 static void pubkey_reset(Authctxt *); 396 static struct sshkey *load_identity_file(Identity *); 397 398 static Authmethod *authmethod_get(char *authlist); 399 static Authmethod *authmethod_lookup(const char *name); 400 static char *authmethods_get(void); 401 402 Authmethod authmethods[] = { 403 #ifdef GSSAPI 404 {"gssapi-with-mic", 405 userauth_gssapi, 406 userauth_gssapi_cleanup, 407 &options.gss_authentication, 408 NULL}, 409 #endif 410 {"hostbased", 411 userauth_hostbased, 412 NULL, 413 &options.hostbased_authentication, 414 NULL}, 415 {"publickey", 416 userauth_pubkey, 417 NULL, 418 &options.pubkey_authentication, 419 NULL}, 420 {"keyboard-interactive", 421 userauth_kbdint, 422 NULL, 423 &options.kbd_interactive_authentication, 424 &options.batch_mode}, 425 {"password", 426 userauth_passwd, 427 NULL, 428 &options.password_authentication, 429 &options.batch_mode}, 430 {"none", 431 userauth_none, 432 NULL, 433 NULL, 434 NULL}, 435 {NULL, NULL, NULL, NULL, NULL} 436 }; 437 438 void 439 ssh_userauth2(struct ssh *ssh, const char *local_user, 440 const char *server_user, char *host, Sensitive *sensitive) 441 { 442 Authctxt authctxt; 443 int r; 444 445 if (options.preferred_authentications == NULL) 446 options.preferred_authentications = authmethods_get(); 447 448 /* setup authentication context */ 449 memset(&authctxt, 0, sizeof(authctxt)); 450 authctxt.server_user = server_user; 451 authctxt.local_user = local_user; 452 authctxt.host = host; 453 authctxt.service = "ssh-connection"; /* service name */ 454 authctxt.success = 0; 455 authctxt.method = authmethod_lookup("none"); 456 authctxt.authlist = NULL; 457 authctxt.methoddata = NULL; 458 authctxt.sensitive = sensitive; 459 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 460 authctxt.info_req_seen = 0; 461 authctxt.attempt_kbdint = 0; 462 authctxt.attempt_passwd = 0; 463 #if GSSAPI 464 authctxt.gss_supported_mechs = NULL; 465 authctxt.mech_tried = 0; 466 #endif 467 authctxt.agent_fd = -1; 468 pubkey_prepare(ssh, &authctxt); 469 if (authctxt.method == NULL) { 470 fatal_f("internal error: cannot send userauth none request"); 471 } 472 473 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 474 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 475 (r = sshpkt_send(ssh)) != 0) 476 fatal_fr(r, "send packet"); 477 478 ssh->authctxt = &authctxt; 479 ssh_dispatch_init(ssh, &input_userauth_error); 480 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 481 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 482 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 483 pubkey_cleanup(ssh); 484 ssh->authctxt = NULL; 485 486 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 487 488 if (!authctxt.success) 489 fatal("Authentication failed."); 490 if (ssh_packet_connection_is_on_socket(ssh)) { 491 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 492 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 493 authctxt.method->name); 494 } else { 495 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 496 authctxt.method->name); 497 } 498 } 499 500 /* ARGSUSED */ 501 static int 502 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 503 { 504 int r; 505 506 if (ssh_packet_remaining(ssh) > 0) { 507 char *reply; 508 509 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 510 goto out; 511 debug2("service_accept: %s", reply); 512 free(reply); 513 } else { 514 debug2("buggy server: service_accept w/o service"); 515 } 516 if ((r = sshpkt_get_end(ssh)) != 0) 517 goto out; 518 debug("SSH2_MSG_SERVICE_ACCEPT received"); 519 520 /* initial userauth request */ 521 userauth_none(ssh); 522 523 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 524 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 525 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 526 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 527 r = 0; 528 out: 529 return r; 530 } 531 532 /* ARGSUSED */ 533 static int 534 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 535 { 536 return kex_input_ext_info(type, seqnr, ssh); 537 } 538 539 void 540 userauth(struct ssh *ssh, char *authlist) 541 { 542 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 543 544 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 545 authctxt->method->cleanup(ssh); 546 547 free(authctxt->methoddata); 548 authctxt->methoddata = NULL; 549 if (authlist == NULL) { 550 authlist = authctxt->authlist; 551 } else { 552 free(authctxt->authlist); 553 authctxt->authlist = authlist; 554 } 555 for (;;) { 556 Authmethod *method = authmethod_get(authlist); 557 if (method == NULL) 558 fatal("%s@%s: Permission denied (%s).", 559 authctxt->server_user, authctxt->host, authlist); 560 authctxt->method = method; 561 562 /* reset the per method handler */ 563 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 564 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 565 566 /* and try new method */ 567 if (method->userauth(ssh) != 0) { 568 debug2("we sent a %s packet, wait for reply", method->name); 569 break; 570 } else { 571 debug2("we did not send a packet, disable method"); 572 method->enabled = NULL; 573 } 574 } 575 } 576 577 /* ARGSUSED */ 578 static int 579 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 580 { 581 fatal_f("bad message during authentication: type %d", type); 582 return 0; 583 } 584 585 /* ARGSUSED */ 586 static int 587 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 588 { 589 char *msg = NULL; 590 size_t len; 591 int r; 592 593 debug3_f("entering"); 594 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 595 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 596 goto out; 597 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 598 fmprintf(stderr, "%s", msg); 599 r = 0; 600 out: 601 free(msg); 602 return r; 603 } 604 605 /* ARGSUSED */ 606 static int 607 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 608 { 609 Authctxt *authctxt = ssh->authctxt; 610 611 if (authctxt == NULL) 612 fatal_f("no authentication context"); 613 free(authctxt->authlist); 614 authctxt->authlist = NULL; 615 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 616 authctxt->method->cleanup(ssh); 617 free(authctxt->methoddata); 618 authctxt->methoddata = NULL; 619 authctxt->success = 1; /* break out */ 620 return 0; 621 } 622 623 #if 0 624 static int 625 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 626 { 627 Authctxt *authctxt = ssh->authctxt; 628 629 if (authctxt == NULL) 630 fatal_f("no authentication context"); 631 632 fatal("Unexpected authentication success during %s.", 633 authctxt->method->name); 634 return 0; 635 } 636 #endif 637 638 /* ARGSUSED */ 639 static int 640 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 641 { 642 Authctxt *authctxt = ssh->authctxt; 643 char *authlist = NULL; 644 u_char partial; 645 646 if (authctxt == NULL) 647 fatal("input_userauth_failure: no authentication context"); 648 649 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 650 sshpkt_get_u8(ssh, &partial) != 0 || 651 sshpkt_get_end(ssh) != 0) 652 goto out; 653 654 if (partial != 0) { 655 verbose("Authenticated using \"%s\" with partial success.", 656 authctxt->method->name); 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 ssh->kex->session_id); 883 884 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 885 fatal_f("sshbuf_mutable_ptr failed"); 886 gssbuf.length = sshbuf_len(b); 887 888 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 889 890 if (!GSS_ERROR(status)) { 891 if ((r = sshpkt_start(ssh, 892 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 893 (r = sshpkt_put_string(ssh, mic.value, 894 mic.length)) != 0 || 895 (r = sshpkt_send(ssh)) != 0) 896 fatal_fr(r, "send MIC"); 897 } 898 899 sshbuf_free(b); 900 gss_release_buffer(&ms, &mic); 901 } 902 } 903 904 return status; 905 } 906 907 /* ARGSUSED */ 908 static int 909 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 910 { 911 Authctxt *authctxt = ssh->authctxt; 912 Gssctxt *gssctxt; 913 size_t oidlen; 914 u_char *oidv = NULL; 915 int r; 916 917 if (authctxt == NULL) 918 fatal("input_gssapi_response: no authentication context"); 919 gssctxt = authctxt->methoddata; 920 921 /* Setup our OID */ 922 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 923 goto done; 924 925 if (oidlen <= 2 || 926 oidv[0] != SSH_GSS_OIDTYPE || 927 oidv[1] != oidlen - 2) { 928 debug("Badly encoded mechanism OID received"); 929 userauth(ssh, NULL); 930 goto ok; 931 } 932 933 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 934 fatal("Server returned different OID than expected"); 935 936 if ((r = sshpkt_get_end(ssh)) != 0) 937 goto done; 938 939 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 940 /* Start again with next method on list */ 941 debug("Trying to start again"); 942 userauth(ssh, NULL); 943 goto ok; 944 } 945 ok: 946 r = 0; 947 done: 948 free(oidv); 949 return r; 950 } 951 952 /* ARGSUSED */ 953 static int 954 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 955 { 956 Authctxt *authctxt = ssh->authctxt; 957 gss_buffer_desc recv_tok; 958 u_char *p = NULL; 959 size_t len; 960 OM_uint32 status; 961 int r; 962 963 if (authctxt == NULL) 964 fatal("input_gssapi_response: no authentication context"); 965 966 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 967 (r = sshpkt_get_end(ssh)) != 0) 968 goto out; 969 970 recv_tok.value = p; 971 recv_tok.length = len; 972 status = process_gssapi_token(ssh, &recv_tok); 973 974 /* Start again with the next method in the list */ 975 if (GSS_ERROR(status)) { 976 userauth(ssh, NULL); 977 /* ok */ 978 } 979 r = 0; 980 out: 981 free(p); 982 return r; 983 } 984 985 /* ARGSUSED */ 986 static int 987 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 988 { 989 Authctxt *authctxt = ssh->authctxt; 990 Gssctxt *gssctxt; 991 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 992 gss_buffer_desc recv_tok; 993 OM_uint32 ms; 994 u_char *p = NULL; 995 size_t len; 996 int r; 997 998 if (authctxt == NULL) 999 fatal("input_gssapi_response: no authentication context"); 1000 gssctxt = authctxt->methoddata; 1001 1002 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1003 (r = sshpkt_get_end(ssh)) != 0) { 1004 free(p); 1005 return r; 1006 } 1007 1008 /* Stick it into GSSAPI and see what it says */ 1009 recv_tok.value = p; 1010 recv_tok.length = len; 1011 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1012 &recv_tok, &send_tok, NULL); 1013 free(p); 1014 gss_release_buffer(&ms, &send_tok); 1015 1016 /* Server will be returning a failed packet after this one */ 1017 return 0; 1018 } 1019 1020 /* ARGSUSED */ 1021 static int 1022 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1023 { 1024 char *msg = NULL; 1025 char *lang = NULL; 1026 int r; 1027 1028 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1029 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1030 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1031 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1032 goto out; 1033 r = sshpkt_get_end(ssh); 1034 debug("Server GSSAPI Error:\n%s", msg); 1035 out: 1036 free(msg); 1037 free(lang); 1038 return r; 1039 } 1040 #endif /* GSSAPI */ 1041 1042 static int 1043 userauth_none(struct ssh *ssh) 1044 { 1045 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1046 int r; 1047 1048 /* initial userauth request */ 1049 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1050 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1051 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1052 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1053 (r = sshpkt_send(ssh)) != 0) 1054 fatal_fr(r, "send packet"); 1055 return 1; 1056 } 1057 1058 static int 1059 userauth_passwd(struct ssh *ssh) 1060 { 1061 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1062 char *password, *prompt = NULL; 1063 const char *host = options.host_key_alias ? options.host_key_alias : 1064 authctxt->host; 1065 int r; 1066 1067 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1068 return 0; 1069 1070 if (authctxt->attempt_passwd != 1) 1071 error("Permission denied, please try again."); 1072 1073 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1074 password = read_passphrase(prompt, 0); 1075 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1076 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1077 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1078 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1079 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1080 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1081 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1082 (r = sshpkt_send(ssh)) != 0) 1083 fatal_fr(r, "send packet"); 1084 1085 free(prompt); 1086 if (password != NULL) 1087 freezero(password, strlen(password)); 1088 1089 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1090 &input_userauth_passwd_changereq); 1091 1092 return 1; 1093 } 1094 1095 /* 1096 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1097 */ 1098 /* ARGSUSED */ 1099 static int 1100 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1101 { 1102 Authctxt *authctxt = ssh->authctxt; 1103 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1104 char prompt[256]; 1105 const char *host; 1106 int r; 1107 1108 debug2("input_userauth_passwd_changereq"); 1109 1110 if (authctxt == NULL) 1111 fatal("input_userauth_passwd_changereq: " 1112 "no authentication context"); 1113 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1114 1115 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1116 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1117 goto out; 1118 if (strlen(info) > 0) 1119 logit("%s", info); 1120 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1121 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1122 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1123 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1124 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1125 goto out; 1126 1127 snprintf(prompt, sizeof(prompt), 1128 "Enter %.30s@%.128s's old password: ", 1129 authctxt->server_user, host); 1130 password = read_passphrase(prompt, 0); 1131 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1132 goto out; 1133 1134 freezero(password, strlen(password)); 1135 password = NULL; 1136 while (password == NULL) { 1137 snprintf(prompt, sizeof(prompt), 1138 "Enter %.30s@%.128s's new password: ", 1139 authctxt->server_user, host); 1140 password = read_passphrase(prompt, RP_ALLOW_EOF); 1141 if (password == NULL) { 1142 /* bail out */ 1143 r = 0; 1144 goto out; 1145 } 1146 snprintf(prompt, sizeof(prompt), 1147 "Retype %.30s@%.128s's new password: ", 1148 authctxt->server_user, host); 1149 retype = read_passphrase(prompt, 0); 1150 if (strcmp(password, retype) != 0) { 1151 freezero(password, strlen(password)); 1152 logit("Mismatch; try again, EOF to quit."); 1153 password = NULL; 1154 } 1155 freezero(retype, strlen(retype)); 1156 } 1157 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1158 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1159 (r = sshpkt_send(ssh)) != 0) 1160 goto out; 1161 1162 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1163 &input_userauth_passwd_changereq); 1164 r = 0; 1165 out: 1166 if (password) 1167 freezero(password, strlen(password)); 1168 free(info); 1169 free(lang); 1170 return r; 1171 } 1172 1173 /* 1174 * Select an algorithm for publickey signatures. 1175 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1176 * 1177 * Call with ssh==NULL to ignore server-sig-algs extension list and 1178 * only attempt with the key's base signature type. 1179 */ 1180 static char * 1181 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1182 { 1183 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1184 const char *server_sig_algs; 1185 1186 /* 1187 * The signature algorithm will only differ from the key algorithm 1188 * for RSA keys/certs and when the server advertises support for 1189 * newer (SHA2) algorithms. 1190 */ 1191 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1192 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1193 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1194 /* Filter base key signature alg against our configuration */ 1195 return match_list(sshkey_ssh_name(key), 1196 options.pubkey_accepted_algos, NULL); 1197 } 1198 1199 /* 1200 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1201 * fails to advertise it via SSH2_MSG_EXT_INFO. 1202 */ 1203 server_sig_algs = ssh->kex->server_sig_algs; 1204 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1205 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1206 1207 /* 1208 * For RSA keys/certs, since these might have a different sig type: 1209 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1210 * that also appears in the supported signature algorithms list from 1211 * the server. 1212 */ 1213 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1214 while ((cp = strsep(&allowed, ",")) != NULL) { 1215 if (sshkey_type_from_name(cp) != key->type) 1216 continue; 1217 tmp = match_list(sshkey_sigalg_by_name(cp), 1218 server_sig_algs, NULL); 1219 if (tmp != NULL) 1220 alg = xstrdup(cp); 1221 free(tmp); 1222 if (alg != NULL) 1223 break; 1224 } 1225 free(oallowed); 1226 return alg; 1227 } 1228 1229 static int 1230 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1231 const u_char *data, size_t datalen, u_int compat, const char *alg) 1232 { 1233 struct sshkey *sign_key = NULL, *prv = NULL; 1234 int retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1235 struct notifier_ctx *notifier = NULL; 1236 char *fp = NULL, *pin = NULL, *prompt = NULL; 1237 1238 *sigp = NULL; 1239 *lenp = 0; 1240 1241 /* The agent supports this key. */ 1242 if (id->key != NULL && id->agent_fd != -1) { 1243 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1244 data, datalen, alg, compat); 1245 } 1246 1247 /* 1248 * We have already loaded the private key or the private key is 1249 * stored in external hardware. 1250 */ 1251 if (id->key != NULL && 1252 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1253 sign_key = id->key; 1254 } else { 1255 /* Load the private key from the file. */ 1256 if ((prv = load_identity_file(id)) == NULL) 1257 return SSH_ERR_KEY_NOT_FOUND; 1258 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1259 error_f("private key %s contents do not match public", 1260 id->filename); 1261 r = SSH_ERR_KEY_NOT_FOUND; 1262 goto out; 1263 } 1264 sign_key = prv; 1265 if (sshkey_is_sk(sign_key)) { 1266 if ((sign_key->sk_flags & 1267 SSH_SK_USER_VERIFICATION_REQD)) { 1268 retry_pin: 1269 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1270 sshkey_type(sign_key), id->filename); 1271 pin = read_passphrase(prompt, 0); 1272 } 1273 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1274 /* XXX should batch mode just skip these? */ 1275 if ((fp = sshkey_fingerprint(sign_key, 1276 options.fingerprint_hash, 1277 SSH_FP_DEFAULT)) == NULL) 1278 fatal_f("fingerprint failed"); 1279 notifier = notify_start(options.batch_mode, 1280 "Confirm user presence for key %s %s", 1281 sshkey_type(sign_key), fp); 1282 free(fp); 1283 } 1284 } 1285 } 1286 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1287 alg, options.sk_provider, pin, compat)) != 0) { 1288 debug_fr(r, "sshkey_sign"); 1289 if (pin == NULL && !retried && sshkey_is_sk(sign_key) && 1290 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1291 notify_complete(notifier, NULL); 1292 notifier = NULL; 1293 retried = 1; 1294 goto retry_pin; 1295 } 1296 goto out; 1297 } 1298 1299 /* 1300 * PKCS#11 tokens may not support all signature algorithms, 1301 * so check what we get back. 1302 */ 1303 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1304 debug_fr(r, "sshkey_check_sigtype"); 1305 goto out; 1306 } 1307 /* success */ 1308 r = 0; 1309 out: 1310 free(prompt); 1311 if (pin != NULL) 1312 freezero(pin, strlen(pin)); 1313 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1314 sshkey_free(prv); 1315 return r; 1316 } 1317 1318 static int 1319 id_filename_matches(Identity *id, Identity *private_id) 1320 { 1321 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1322 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1323 size_t i, slen; 1324 1325 if (strcmp(id->filename, private_id->filename) == 0) 1326 return 1; 1327 for (i = 0; suffixes[i]; i++) { 1328 slen = strlen(suffixes[i]); 1329 if (len > slen && plen == len - slen && 1330 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1331 memcmp(id->filename, private_id->filename, plen) == 0) 1332 return 1; 1333 } 1334 return 0; 1335 } 1336 1337 static int 1338 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1339 { 1340 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1341 struct sshbuf *b = NULL; 1342 Identity *private_id, *sign_id = NULL; 1343 u_char *signature = NULL; 1344 size_t slen = 0, skip = 0; 1345 int r, fallback_sigtype, sent = 0; 1346 char *alg = NULL, *fp = NULL; 1347 const char *loc = "", *method = "publickey"; 1348 int hostbound = 0; 1349 1350 /* prefer host-bound pubkey signatures if supported by server */ 1351 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1352 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1353 hostbound = 1; 1354 method = "publickey-hostbound-v00@openssh.com"; 1355 } 1356 1357 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1358 SSH_FP_DEFAULT)) == NULL) 1359 return 0; 1360 1361 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1362 1363 /* 1364 * If the key is an certificate, try to find a matching private key 1365 * and use it to complete the signature. 1366 * If no such private key exists, fall back to trying the certificate 1367 * key itself in case it has a private half already loaded. 1368 * This will try to set sign_id to the private key that will perform 1369 * the signature. 1370 */ 1371 if (sshkey_is_cert(id->key)) { 1372 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1373 if (sshkey_equal_public(id->key, private_id->key) && 1374 id->key->type != private_id->key->type) { 1375 sign_id = private_id; 1376 break; 1377 } 1378 } 1379 /* 1380 * Exact key matches are preferred, but also allow 1381 * filename matches for non-PKCS#11/agent keys that 1382 * didn't load public keys. This supports the case 1383 * of keeping just a private key file and public 1384 * certificate on disk. 1385 */ 1386 if (sign_id == NULL && 1387 !id->isprivate && id->agent_fd == -1 && 1388 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1389 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1390 if (private_id->key == NULL && 1391 id_filename_matches(id, private_id)) { 1392 sign_id = private_id; 1393 break; 1394 } 1395 } 1396 } 1397 if (sign_id != NULL) { 1398 debug2_f("using private key \"%s\"%s for " 1399 "certificate", sign_id->filename, 1400 sign_id->agent_fd != -1 ? " from agent" : ""); 1401 } else { 1402 debug_f("no separate private key for certificate " 1403 "\"%s\"", id->filename); 1404 } 1405 } 1406 1407 /* 1408 * If the above didn't select another identity to do the signing 1409 * then default to the one we started with. 1410 */ 1411 if (sign_id == NULL) 1412 sign_id = id; 1413 1414 /* assemble and sign data */ 1415 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1416 free(alg); 1417 slen = 0; 1418 signature = NULL; 1419 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1420 id->key)) == NULL) { 1421 error_f("no mutual signature supported"); 1422 goto out; 1423 } 1424 debug3_f("signing using %s %s", alg, fp); 1425 1426 sshbuf_free(b); 1427 if ((b = sshbuf_new()) == NULL) 1428 fatal_f("sshbuf_new failed"); 1429 if (ssh->compat & SSH_OLD_SESSIONID) { 1430 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1431 fatal_fr(r, "sshbuf_putb"); 1432 } else { 1433 if ((r = sshbuf_put_stringb(b, 1434 ssh->kex->session_id)) != 0) 1435 fatal_fr(r, "sshbuf_put_stringb"); 1436 } 1437 skip = sshbuf_len(b); 1438 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1439 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1440 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1441 (r = sshbuf_put_cstring(b, method)) != 0 || 1442 (r = sshbuf_put_u8(b, 1)) != 0 || 1443 (r = sshbuf_put_cstring(b, alg)) != 0 || 1444 (r = sshkey_puts(id->key, b)) != 0) { 1445 fatal_fr(r, "assemble signed data"); 1446 } 1447 if (hostbound) { 1448 if (ssh->kex->initial_hostkey == NULL) { 1449 fatal_f("internal error: initial hostkey " 1450 "not recorded"); 1451 } 1452 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1453 fatal_fr(r, "assemble %s hostkey", method); 1454 } 1455 /* generate signature */ 1456 r = identity_sign(sign_id, &signature, &slen, 1457 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1458 if (r == 0) 1459 break; 1460 else if (r == SSH_ERR_KEY_NOT_FOUND) 1461 goto out; /* soft failure */ 1462 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1463 !fallback_sigtype) { 1464 if (sign_id->agent_fd != -1) 1465 loc = "agent "; 1466 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1467 loc = "token "; 1468 logit("%skey %s %s returned incorrect signature type", 1469 loc, sshkey_type(id->key), fp); 1470 continue; 1471 } 1472 error_fr(r, "signing failed for %s \"%s\"%s", 1473 sshkey_type(sign_id->key), sign_id->filename, 1474 id->agent_fd != -1 ? " from agent" : ""); 1475 goto out; 1476 } 1477 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1478 fatal_f("no signature"); 1479 1480 /* append signature */ 1481 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1482 fatal_fr(r, "append signature"); 1483 1484 #ifdef DEBUG_PK 1485 sshbuf_dump(b, stderr); 1486 #endif 1487 /* skip session id and packet type */ 1488 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1489 fatal_fr(r, "consume"); 1490 1491 /* put remaining data from buffer into packet */ 1492 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1493 (r = sshpkt_putb(ssh, b)) != 0 || 1494 (r = sshpkt_send(ssh)) != 0) 1495 fatal_fr(r, "enqueue request"); 1496 1497 /* success */ 1498 sent = 1; 1499 1500 out: 1501 free(fp); 1502 free(alg); 1503 sshbuf_free(b); 1504 freezero(signature, slen); 1505 return sent; 1506 } 1507 1508 static int 1509 send_pubkey_test(struct ssh *ssh, Identity *id) 1510 { 1511 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1512 u_char *blob = NULL; 1513 char *alg = NULL; 1514 size_t bloblen; 1515 u_int have_sig = 0; 1516 int sent = 0, r; 1517 1518 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1519 debug_f("no mutual signature algorithm"); 1520 goto out; 1521 } 1522 1523 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1524 /* we cannot handle this key */ 1525 debug3_f("cannot handle key"); 1526 goto out; 1527 } 1528 /* register callback for USERAUTH_PK_OK message */ 1529 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1530 1531 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1532 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1533 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1534 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1535 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1536 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1537 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1538 (r = sshpkt_send(ssh)) != 0) 1539 fatal_fr(r, "send packet"); 1540 sent = 1; 1541 1542 out: 1543 free(alg); 1544 free(blob); 1545 return sent; 1546 } 1547 1548 static struct sshkey * 1549 load_identity_file(Identity *id) 1550 { 1551 struct sshkey *private = NULL; 1552 char prompt[300], *passphrase, *comment; 1553 int r, quit = 0, i; 1554 struct stat st; 1555 1556 if (stat(id->filename, &st) == -1) { 1557 do_log2(id->userprovided ? 1558 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1559 "no such identity: %s: %s", id->filename, strerror(errno)); 1560 return NULL; 1561 } 1562 snprintf(prompt, sizeof prompt, 1563 "Enter passphrase for key '%.100s': ", id->filename); 1564 for (i = 0; i <= options.number_of_password_prompts; i++) { 1565 if (i == 0) 1566 passphrase = ""; 1567 else { 1568 passphrase = read_passphrase(prompt, 0); 1569 if (*passphrase == '\0') { 1570 debug2("no passphrase given, try next key"); 1571 free(passphrase); 1572 break; 1573 } 1574 } 1575 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1576 passphrase, &private, &comment))) { 1577 case 0: 1578 break; 1579 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1580 if (options.batch_mode) { 1581 quit = 1; 1582 break; 1583 } 1584 if (i != 0) 1585 debug2("bad passphrase given, try again..."); 1586 break; 1587 case SSH_ERR_SYSTEM_ERROR: 1588 if (errno == ENOENT) { 1589 debug2_r(r, "Load key \"%s\"", id->filename); 1590 quit = 1; 1591 break; 1592 } 1593 /* FALLTHROUGH */ 1594 default: 1595 error_r(r, "Load key \"%s\"", id->filename); 1596 quit = 1; 1597 break; 1598 } 1599 if (private != NULL && sshkey_is_sk(private) && 1600 options.sk_provider == NULL) { 1601 debug("key \"%s\" is an authenticator-hosted key, " 1602 "but no provider specified", id->filename); 1603 sshkey_free(private); 1604 private = NULL; 1605 quit = 1; 1606 } 1607 if (!quit && private != NULL && id->agent_fd == -1 && 1608 !(id->key && id->isprivate)) 1609 maybe_add_key_to_agent(id->filename, private, comment, 1610 passphrase); 1611 if (i > 0) 1612 freezero(passphrase, strlen(passphrase)); 1613 free(comment); 1614 if (private != NULL || quit) 1615 break; 1616 } 1617 return private; 1618 } 1619 1620 static int 1621 key_type_allowed_by_config(struct sshkey *key) 1622 { 1623 if (match_pattern_list(sshkey_ssh_name(key), 1624 options.pubkey_accepted_algos, 0) == 1) 1625 return 1; 1626 1627 /* RSA keys/certs might be allowed by alternate signature types */ 1628 switch (key->type) { 1629 case KEY_RSA: 1630 if (match_pattern_list("rsa-sha2-512", 1631 options.pubkey_accepted_algos, 0) == 1) 1632 return 1; 1633 if (match_pattern_list("rsa-sha2-256", 1634 options.pubkey_accepted_algos, 0) == 1) 1635 return 1; 1636 break; 1637 case KEY_RSA_CERT: 1638 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1639 options.pubkey_accepted_algos, 0) == 1) 1640 return 1; 1641 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1642 options.pubkey_accepted_algos, 0) == 1) 1643 return 1; 1644 break; 1645 } 1646 return 0; 1647 } 1648 1649 /* obtain a list of keys from the agent */ 1650 static int 1651 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1652 struct ssh_identitylist **idlistp) 1653 { 1654 int r, agent_fd; 1655 struct ssh_identitylist *idlist; 1656 1657 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1658 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1659 debug_fr(r, "ssh_get_authentication_socket"); 1660 return r; 1661 } 1662 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1663 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1664 debug_f("bound agent to hostkey"); 1665 else 1666 debug2_fr(r, "ssh_agent_bind_hostkey"); 1667 1668 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1669 debug_fr(r, "ssh_fetch_identitylist"); 1670 close(agent_fd); 1671 return r; 1672 } 1673 /* success */ 1674 *agent_fdp = agent_fd; 1675 *idlistp = idlist; 1676 debug_f("agent returned %zu keys", idlist->nkeys); 1677 return 0; 1678 } 1679 1680 /* 1681 * try keys in the following order: 1682 * 1. certificates listed in the config file 1683 * 2. other input certificates 1684 * 3. agent keys that are found in the config file 1685 * 4. other agent keys 1686 * 5. keys that are only listed in the config file 1687 */ 1688 static void 1689 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1690 { 1691 struct identity *id, *id2, *tmp; 1692 struct idlist agent, files, *preferred; 1693 struct sshkey *key; 1694 int agent_fd = -1, i, r, found; 1695 size_t j; 1696 struct ssh_identitylist *idlist; 1697 char *ident; 1698 1699 TAILQ_INIT(&agent); /* keys from the agent */ 1700 TAILQ_INIT(&files); /* keys from the config file */ 1701 preferred = &authctxt->keys; 1702 TAILQ_INIT(preferred); /* preferred order of keys */ 1703 1704 /* list of keys stored in the filesystem and PKCS#11 */ 1705 for (i = 0; i < options.num_identity_files; i++) { 1706 key = options.identity_keys[i]; 1707 if (key && key->cert && 1708 key->cert->type != SSH2_CERT_TYPE_USER) { 1709 debug_f("ignoring certificate %s: not a user " 1710 "certificate", options.identity_files[i]); 1711 continue; 1712 } 1713 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1714 debug_f("ignoring authenticator-hosted key %s as no " 1715 "SecurityKeyProvider has been specified", 1716 options.identity_files[i]); 1717 continue; 1718 } 1719 options.identity_keys[i] = NULL; 1720 id = xcalloc(1, sizeof(*id)); 1721 id->agent_fd = -1; 1722 id->key = key; 1723 id->filename = xstrdup(options.identity_files[i]); 1724 id->userprovided = options.identity_file_userprovided[i]; 1725 TAILQ_INSERT_TAIL(&files, id, next); 1726 } 1727 /* list of certificates specified by user */ 1728 for (i = 0; i < options.num_certificate_files; i++) { 1729 key = options.certificates[i]; 1730 if (!sshkey_is_cert(key) || key->cert == NULL || 1731 key->cert->type != SSH2_CERT_TYPE_USER) { 1732 debug_f("ignoring certificate %s: not a user " 1733 "certificate", options.identity_files[i]); 1734 continue; 1735 } 1736 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1737 debug_f("ignoring authenticator-hosted key " 1738 "certificate %s as no " 1739 "SecurityKeyProvider has been specified", 1740 options.identity_files[i]); 1741 continue; 1742 } 1743 id = xcalloc(1, sizeof(*id)); 1744 id->agent_fd = -1; 1745 id->key = key; 1746 id->filename = xstrdup(options.certificate_files[i]); 1747 id->userprovided = options.certificate_file_userprovided[i]; 1748 TAILQ_INSERT_TAIL(preferred, id, next); 1749 } 1750 /* list of keys supported by the agent */ 1751 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1752 for (j = 0; j < idlist->nkeys; j++) { 1753 found = 0; 1754 TAILQ_FOREACH(id, &files, next) { 1755 /* 1756 * agent keys from the config file are 1757 * preferred 1758 */ 1759 if (sshkey_equal(idlist->keys[j], id->key)) { 1760 TAILQ_REMOVE(&files, id, next); 1761 TAILQ_INSERT_TAIL(preferred, id, next); 1762 id->agent_fd = agent_fd; 1763 found = 1; 1764 break; 1765 } 1766 } 1767 if (!found && !options.identities_only) { 1768 id = xcalloc(1, sizeof(*id)); 1769 /* XXX "steals" key/comment from idlist */ 1770 id->key = idlist->keys[j]; 1771 id->filename = idlist->comments[j]; 1772 idlist->keys[j] = NULL; 1773 idlist->comments[j] = NULL; 1774 id->agent_fd = agent_fd; 1775 TAILQ_INSERT_TAIL(&agent, id, next); 1776 } 1777 } 1778 ssh_free_identitylist(idlist); 1779 /* append remaining agent keys */ 1780 TAILQ_CONCAT(preferred, &agent, next); 1781 authctxt->agent_fd = agent_fd; 1782 } 1783 /* Prefer PKCS11 keys that are explicitly listed */ 1784 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1785 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1786 continue; 1787 found = 0; 1788 TAILQ_FOREACH(id2, &files, next) { 1789 if (id2->key == NULL || 1790 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1791 continue; 1792 if (sshkey_equal(id->key, id2->key)) { 1793 TAILQ_REMOVE(&files, id, next); 1794 TAILQ_INSERT_TAIL(preferred, id, next); 1795 found = 1; 1796 break; 1797 } 1798 } 1799 /* If IdentitiesOnly set and key not found then don't use it */ 1800 if (!found && options.identities_only) { 1801 TAILQ_REMOVE(&files, id, next); 1802 freezero(id, sizeof(*id)); 1803 } 1804 } 1805 /* append remaining keys from the config file */ 1806 TAILQ_CONCAT(preferred, &files, next); 1807 /* finally, filter by PubkeyAcceptedAlgorithms */ 1808 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1809 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1810 debug("Skipping %s key %s - " 1811 "corresponding algo not in PubkeyAcceptedAlgorithms", 1812 sshkey_ssh_name(id->key), id->filename); 1813 TAILQ_REMOVE(preferred, id, next); 1814 sshkey_free(id->key); 1815 free(id->filename); 1816 memset(id, 0, sizeof(*id)); 1817 continue; 1818 } 1819 } 1820 /* List the keys we plan on using */ 1821 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1822 ident = format_identity(id); 1823 debug("Will attempt key: %s", ident); 1824 free(ident); 1825 } 1826 debug2_f("done"); 1827 } 1828 1829 static void 1830 pubkey_cleanup(struct ssh *ssh) 1831 { 1832 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1833 Identity *id; 1834 1835 if (authctxt->agent_fd != -1) { 1836 ssh_close_authentication_socket(authctxt->agent_fd); 1837 authctxt->agent_fd = -1; 1838 } 1839 for (id = TAILQ_FIRST(&authctxt->keys); id; 1840 id = TAILQ_FIRST(&authctxt->keys)) { 1841 TAILQ_REMOVE(&authctxt->keys, id, next); 1842 sshkey_free(id->key); 1843 free(id->filename); 1844 free(id); 1845 } 1846 } 1847 1848 static void 1849 pubkey_reset(Authctxt *authctxt) 1850 { 1851 Identity *id; 1852 1853 TAILQ_FOREACH(id, &authctxt->keys, next) 1854 id->tried = 0; 1855 } 1856 1857 static int 1858 try_identity(struct ssh *ssh, Identity *id) 1859 { 1860 if (!id->key) 1861 return (0); 1862 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1863 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 1864 debug("Skipped %s key %s for RSA/MD5 server", 1865 sshkey_type(id->key), id->filename); 1866 return (0); 1867 } 1868 return 1; 1869 } 1870 1871 static int 1872 userauth_pubkey(struct ssh *ssh) 1873 { 1874 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1875 Identity *id; 1876 int sent = 0; 1877 char *ident; 1878 1879 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1880 if (id->tried++) 1881 return (0); 1882 /* move key to the end of the queue */ 1883 TAILQ_REMOVE(&authctxt->keys, id, next); 1884 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1885 /* 1886 * send a test message if we have the public key. for 1887 * encrypted keys we cannot do this and have to load the 1888 * private key instead 1889 */ 1890 if (id->key != NULL) { 1891 if (try_identity(ssh, id)) { 1892 ident = format_identity(id); 1893 debug("Offering public key: %s", ident); 1894 free(ident); 1895 sent = send_pubkey_test(ssh, id); 1896 } 1897 } else { 1898 debug("Trying private key: %s", id->filename); 1899 id->key = load_identity_file(id); 1900 if (id->key != NULL) { 1901 if (try_identity(ssh, id)) { 1902 id->isprivate = 1; 1903 sent = sign_and_send_pubkey(ssh, id); 1904 } 1905 sshkey_free(id->key); 1906 id->key = NULL; 1907 id->isprivate = 0; 1908 } 1909 } 1910 if (sent) 1911 return (sent); 1912 } 1913 return (0); 1914 } 1915 1916 /* 1917 * Send userauth request message specifying keyboard-interactive method. 1918 */ 1919 static int 1920 userauth_kbdint(struct ssh *ssh) 1921 { 1922 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1923 int r; 1924 1925 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1926 return 0; 1927 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1928 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1929 debug3("userauth_kbdint: disable: no info_req_seen"); 1930 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1931 return 0; 1932 } 1933 1934 debug2("userauth_kbdint"); 1935 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1936 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1937 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1938 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1939 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1940 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1941 options.kbd_interactive_devices : "")) != 0 || 1942 (r = sshpkt_send(ssh)) != 0) 1943 fatal_fr(r, "send packet"); 1944 1945 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1946 return 1; 1947 } 1948 1949 /* 1950 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1951 */ 1952 static int 1953 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1954 { 1955 Authctxt *authctxt = ssh->authctxt; 1956 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1957 char *display_prompt = NULL, *response = NULL; 1958 u_char echo = 0; 1959 u_int num_prompts, i; 1960 int r; 1961 1962 debug2_f("entering"); 1963 1964 if (authctxt == NULL) 1965 fatal_f("no authentication context"); 1966 1967 authctxt->info_req_seen = 1; 1968 1969 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1970 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1971 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1972 goto out; 1973 if (strlen(name) > 0) 1974 logit("%s", name); 1975 if (strlen(inst) > 0) 1976 logit("%s", inst); 1977 1978 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1979 goto out; 1980 /* 1981 * Begin to build info response packet based on prompts requested. 1982 * We commit to providing the correct number of responses, so if 1983 * further on we run into a problem that prevents this, we have to 1984 * be sure and clean this up and send a correct error response. 1985 */ 1986 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1987 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1988 goto out; 1989 1990 debug2_f("num_prompts %d", num_prompts); 1991 for (i = 0; i < num_prompts; i++) { 1992 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1993 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1994 goto out; 1995 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1996 authctxt->server_user, options.host_key_alias ? 1997 options.host_key_alias : authctxt->host, prompt) == -1) 1998 fatal_f("asmprintf failed"); 1999 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 2000 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 2001 goto out; 2002 freezero(response, strlen(response)); 2003 free(prompt); 2004 free(display_prompt); 2005 display_prompt = response = prompt = NULL; 2006 } 2007 /* done with parsing incoming message. */ 2008 if ((r = sshpkt_get_end(ssh)) != 0 || 2009 (r = sshpkt_add_padding(ssh, 64)) != 0) 2010 goto out; 2011 r = sshpkt_send(ssh); 2012 out: 2013 if (response) 2014 freezero(response, strlen(response)); 2015 free(prompt); 2016 free(display_prompt); 2017 free(name); 2018 free(inst); 2019 free(lang); 2020 return r; 2021 } 2022 2023 static int 2024 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2025 const u_char *data, size_t datalen) 2026 { 2027 struct sshbuf *b; 2028 struct stat st; 2029 pid_t pid; 2030 int r, to[2], from[2], status; 2031 int sock = ssh_packet_get_connection_in(ssh); 2032 u_char rversion = 0, version = 2; 2033 void (*osigchld)(int); 2034 2035 *sigp = NULL; 2036 *lenp = 0; 2037 2038 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2039 error_f("not installed: %s", strerror(errno)); 2040 return -1; 2041 } 2042 if (fflush(stdout) != 0) { 2043 error_f("fflush: %s", strerror(errno)); 2044 return -1; 2045 } 2046 if (pipe(to) == -1) { 2047 error_f("pipe: %s", strerror(errno)); 2048 return -1; 2049 } 2050 if (pipe(from) == -1) { 2051 error_f("pipe: %s", strerror(errno)); 2052 return -1; 2053 } 2054 if ((pid = fork()) == -1) { 2055 error_f("fork: %s", strerror(errno)); 2056 return -1; 2057 } 2058 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2059 if (pid == 0) { 2060 close(from[0]); 2061 if (dup2(from[1], STDOUT_FILENO) == -1) 2062 fatal_f("dup2: %s", strerror(errno)); 2063 close(to[1]); 2064 if (dup2(to[0], STDIN_FILENO) == -1) 2065 fatal_f("dup2: %s", strerror(errno)); 2066 close(from[1]); 2067 close(to[0]); 2068 2069 if (dup2(sock, STDERR_FILENO + 1) == -1) 2070 fatal_f("dup2: %s", strerror(errno)); 2071 sock = STDERR_FILENO + 1; 2072 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2073 closefrom(sock + 1); 2074 2075 debug3_f("[child] pid=%ld, exec %s", 2076 (long)getpid(), _PATH_SSH_KEY_SIGN); 2077 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2078 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2079 strerror(errno)); 2080 } 2081 close(from[1]); 2082 close(to[0]); 2083 sock = STDERR_FILENO + 1; 2084 2085 if ((b = sshbuf_new()) == NULL) 2086 fatal_f("sshbuf_new failed"); 2087 /* send # of sock, data to be signed */ 2088 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2089 (r = sshbuf_put_string(b, data, datalen)) != 0) 2090 fatal_fr(r, "buffer error"); 2091 if (ssh_msg_send(to[1], version, b) == -1) 2092 fatal_f("couldn't send request"); 2093 sshbuf_reset(b); 2094 r = ssh_msg_recv(from[0], b); 2095 close(from[0]); 2096 close(to[1]); 2097 if (r < 0) { 2098 error_f("no reply"); 2099 goto fail; 2100 } 2101 2102 errno = 0; 2103 while (waitpid(pid, &status, 0) == -1) { 2104 if (errno != EINTR) { 2105 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2106 goto fail; 2107 } 2108 } 2109 if (!WIFEXITED(status)) { 2110 error_f("exited abnormally"); 2111 goto fail; 2112 } 2113 if (WEXITSTATUS(status) != 0) { 2114 error_f("exited with status %d", WEXITSTATUS(status)); 2115 goto fail; 2116 } 2117 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2118 error_fr(r, "buffer error"); 2119 goto fail; 2120 } 2121 if (rversion != version) { 2122 error_f("bad version"); 2123 goto fail; 2124 } 2125 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2126 error_fr(r, "buffer error"); 2127 fail: 2128 ssh_signal(SIGCHLD, osigchld); 2129 sshbuf_free(b); 2130 return -1; 2131 } 2132 ssh_signal(SIGCHLD, osigchld); 2133 sshbuf_free(b); 2134 2135 return 0; 2136 } 2137 2138 static int 2139 userauth_hostbased(struct ssh *ssh) 2140 { 2141 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2142 struct sshkey *private = NULL; 2143 struct sshbuf *b = NULL; 2144 u_char *sig = NULL, *keyblob = NULL; 2145 char *fp = NULL, *chost = NULL, *lname = NULL; 2146 size_t siglen = 0, keylen = 0; 2147 int i, r, success = 0; 2148 2149 if (authctxt->ktypes == NULL) { 2150 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2151 authctxt->ktypes = authctxt->oktypes; 2152 } 2153 2154 /* 2155 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2156 * trying each hostkey that matches the type in turn. 2157 */ 2158 for (;;) { 2159 if (authctxt->active_ktype == NULL) 2160 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2161 if (authctxt->active_ktype == NULL || 2162 *authctxt->active_ktype == '\0') 2163 break; 2164 debug3_f("trying key type %s", authctxt->active_ktype); 2165 2166 /* check for a useful key */ 2167 private = NULL; 2168 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2169 if (authctxt->sensitive->keys[i] == NULL || 2170 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2171 continue; 2172 if (!sshkey_match_keyname_to_sigalgs( 2173 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2174 authctxt->active_ktype)) 2175 continue; 2176 /* we take and free the key */ 2177 private = authctxt->sensitive->keys[i]; 2178 authctxt->sensitive->keys[i] = NULL; 2179 break; 2180 } 2181 /* Found one */ 2182 if (private != NULL) 2183 break; 2184 /* No more keys of this type; advance */ 2185 authctxt->active_ktype = NULL; 2186 } 2187 if (private == NULL) { 2188 free(authctxt->oktypes); 2189 authctxt->oktypes = authctxt->ktypes = NULL; 2190 authctxt->active_ktype = NULL; 2191 debug("No more client hostkeys for hostbased authentication."); 2192 goto out; 2193 } 2194 2195 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2196 SSH_FP_DEFAULT)) == NULL) { 2197 error_f("sshkey_fingerprint failed"); 2198 goto out; 2199 } 2200 debug_f("trying hostkey %s %s using sigalg %s", 2201 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2202 2203 /* figure out a name for the client host */ 2204 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2205 if (lname == NULL) { 2206 error_f("cannot get local ipaddr/name"); 2207 goto out; 2208 } 2209 2210 /* XXX sshbuf_put_stringf? */ 2211 xasprintf(&chost, "%s.", lname); 2212 debug2_f("chost %s", chost); 2213 2214 /* construct data */ 2215 if ((b = sshbuf_new()) == NULL) { 2216 error_f("sshbuf_new failed"); 2217 goto out; 2218 } 2219 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2220 error_fr(r, "sshkey_to_blob"); 2221 goto out; 2222 } 2223 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2224 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2225 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2226 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2227 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2228 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2229 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2230 (r = sshbuf_put_cstring(b, chost)) != 0 || 2231 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2232 error_fr(r, "buffer error"); 2233 goto out; 2234 } 2235 2236 #ifdef DEBUG_PK 2237 sshbuf_dump(b, stderr); 2238 #endif 2239 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2240 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2241 error("sign using hostkey %s %s failed", 2242 sshkey_ssh_name(private), fp); 2243 goto out; 2244 } 2245 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2246 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2247 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2248 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2249 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2250 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2251 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2252 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2253 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2254 (r = sshpkt_send(ssh)) != 0) { 2255 error_fr(r, "packet error"); 2256 goto out; 2257 } 2258 success = 1; 2259 2260 out: 2261 if (sig != NULL) 2262 freezero(sig, siglen); 2263 free(keyblob); 2264 free(lname); 2265 free(fp); 2266 free(chost); 2267 sshkey_free(private); 2268 sshbuf_free(b); 2269 2270 return success; 2271 } 2272 2273 /* find auth method */ 2274 2275 /* 2276 * given auth method name, if configurable options permit this method fill 2277 * in auth_ident field and return true, otherwise return false. 2278 */ 2279 static int 2280 authmethod_is_enabled(Authmethod *method) 2281 { 2282 if (method == NULL) 2283 return 0; 2284 /* return false if options indicate this method is disabled */ 2285 if (method->enabled == NULL || *method->enabled == 0) 2286 return 0; 2287 /* return false if batch mode is enabled but method needs interactive mode */ 2288 if (method->batch_flag != NULL && *method->batch_flag != 0) 2289 return 0; 2290 return 1; 2291 } 2292 2293 static Authmethod * 2294 authmethod_lookup(const char *name) 2295 { 2296 Authmethod *method = NULL; 2297 if (name != NULL) 2298 for (method = authmethods; method->name != NULL; method++) 2299 if (strcmp(name, method->name) == 0) 2300 return method; 2301 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2302 return NULL; 2303 } 2304 2305 /* XXX internal state */ 2306 static Authmethod *current = NULL; 2307 static char *supported = NULL; 2308 static char *preferred = NULL; 2309 2310 /* 2311 * Given the authentication method list sent by the server, return the 2312 * next method we should try. If the server initially sends a nil list, 2313 * use a built-in default list. 2314 */ 2315 static Authmethod * 2316 authmethod_get(char *authlist) 2317 { 2318 char *name = NULL; 2319 u_int next; 2320 2321 /* Use a suitable default if we're passed a nil list. */ 2322 if (authlist == NULL || strlen(authlist) == 0) 2323 authlist = options.preferred_authentications; 2324 2325 if (supported == NULL || strcmp(authlist, supported) != 0) { 2326 debug3("start over, passed a different list %s", authlist); 2327 free(supported); 2328 supported = xstrdup(authlist); 2329 preferred = options.preferred_authentications; 2330 debug3("preferred %s", preferred); 2331 current = NULL; 2332 } else if (current != NULL && authmethod_is_enabled(current)) 2333 return current; 2334 2335 for (;;) { 2336 if ((name = match_list(preferred, supported, &next)) == NULL) { 2337 debug("No more authentication methods to try."); 2338 current = NULL; 2339 return NULL; 2340 } 2341 preferred += next; 2342 debug3("authmethod_lookup %s", name); 2343 debug3("remaining preferred: %s", preferred); 2344 if ((current = authmethod_lookup(name)) != NULL && 2345 authmethod_is_enabled(current)) { 2346 debug3("authmethod_is_enabled %s", name); 2347 debug("Next authentication method: %s", name); 2348 free(name); 2349 return current; 2350 } 2351 free(name); 2352 } 2353 } 2354 2355 static char * 2356 authmethods_get(void) 2357 { 2358 Authmethod *method = NULL; 2359 struct sshbuf *b; 2360 char *list; 2361 int r; 2362 2363 if ((b = sshbuf_new()) == NULL) 2364 fatal_f("sshbuf_new failed"); 2365 for (method = authmethods; method->name != NULL; method++) { 2366 if (authmethod_is_enabled(method)) { 2367 if ((r = sshbuf_putf(b, "%s%s", 2368 sshbuf_len(b) ? "," : "", method->name)) != 0) 2369 fatal_fr(r, "buffer error"); 2370 } 2371 } 2372 if ((list = sshbuf_dup_string(b)) == NULL) 2373 fatal_f("sshbuf_dup_string failed"); 2374 sshbuf_free(b); 2375 return list; 2376 } 2377