1 /* $OpenBSD: sshconnect2.c,v 1.361 2022/09/17 10:33:18 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 int r; 100 101 if ((r = sshkey_check_rsa_length(hostkey, 102 options.required_rsa_size)) != 0) 103 fatal_r(r, "Bad server host key"); 104 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 105 xxx_conn_info) == -1) 106 fatal("Host key verification failed."); 107 return 0; 108 } 109 110 /* Returns the first item from a comma-separated algorithm list */ 111 static char * 112 first_alg(const char *algs) 113 { 114 char *ret, *cp; 115 116 ret = xstrdup(algs); 117 if ((cp = strchr(ret, ',')) != NULL) 118 *cp = '\0'; 119 return ret; 120 } 121 122 static char * 123 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 124 const struct ssh_conn_info *cinfo) 125 { 126 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 127 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 128 size_t maxlen; 129 struct hostkeys *hostkeys = NULL; 130 int ktype; 131 u_int i; 132 133 /* Find all hostkeys for this hostname */ 134 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 135 hostkeys = init_hostkeys(); 136 for (i = 0; i < options.num_user_hostfiles; i++) 137 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 138 for (i = 0; i < options.num_system_hostfiles; i++) { 139 load_hostkeys(hostkeys, hostname, 140 options.system_hostfiles[i], 0); 141 } 142 if (options.known_hosts_command != NULL) { 143 load_hostkeys_command(hostkeys, options.known_hosts_command, 144 "ORDER", cinfo, NULL, host); 145 } 146 /* 147 * If a plain public key exists that matches the type of the best 148 * preference HostkeyAlgorithms, then use the whole list as is. 149 * Note that we ignore whether the best preference algorithm is a 150 * certificate type, as sshconnect.c will downgrade certs to 151 * plain keys if necessary. 152 */ 153 best = first_alg(options.hostkeyalgorithms); 154 if (lookup_key_in_hostkeys_by_type(hostkeys, 155 sshkey_type_plain(sshkey_type_from_name(best)), 156 sshkey_ecdsa_nid_from_name(best), NULL)) { 157 debug3_f("have matching best-preference key type %s, " 158 "using HostkeyAlgorithms verbatim", best); 159 ret = xstrdup(options.hostkeyalgorithms); 160 goto out; 161 } 162 163 /* 164 * Otherwise, prefer the host key algorithms that match known keys 165 * while keeping the ordering of HostkeyAlgorithms as much as possible. 166 */ 167 oavail = avail = xstrdup(options.hostkeyalgorithms); 168 maxlen = strlen(avail) + 1; 169 first = xmalloc(maxlen); 170 last = xmalloc(maxlen); 171 *first = *last = '\0'; 172 173 #define ALG_APPEND(to, from) \ 174 do { \ 175 if (*to != '\0') \ 176 strlcat(to, ",", maxlen); \ 177 strlcat(to, from, maxlen); \ 178 } while (0) 179 180 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 181 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 182 fatal_f("unknown alg %s", alg); 183 /* 184 * If we have a @cert-authority marker in known_hosts then 185 * prefer all certificate algorithms. 186 */ 187 if (sshkey_type_is_cert(ktype) && 188 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 189 ALG_APPEND(first, alg); 190 continue; 191 } 192 /* If the key appears in known_hosts then prefer it */ 193 if (lookup_key_in_hostkeys_by_type(hostkeys, 194 sshkey_type_plain(ktype), 195 sshkey_ecdsa_nid_from_name(alg), NULL)) { 196 ALG_APPEND(first, alg); 197 continue; 198 } 199 /* Otherwise, put it last */ 200 ALG_APPEND(last, alg); 201 } 202 #undef ALG_APPEND 203 xasprintf(&ret, "%s%s%s", first, 204 (*first == '\0' || *last == '\0') ? "" : ",", last); 205 if (*first != '\0') 206 debug3_f("prefer hostkeyalgs: %s", first); 207 else 208 debug3_f("no algorithms matched; accept original"); 209 out: 210 free(best); 211 free(first); 212 free(last); 213 free(hostname); 214 free(oavail); 215 free_hostkeys(hostkeys); 216 217 return ret; 218 } 219 220 void 221 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 222 const struct ssh_conn_info *cinfo) 223 { 224 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 225 char *s, *all_key; 226 char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; 227 int r, use_known_hosts_order = 0; 228 229 xxx_host = host; 230 xxx_hostaddr = hostaddr; 231 xxx_conn_info = cinfo; 232 233 /* 234 * If the user has not specified HostkeyAlgorithms, or has only 235 * appended or removed algorithms from that list then prefer algorithms 236 * that are in the list that are supported by known_hosts keys. 237 */ 238 if (options.hostkeyalgorithms == NULL || 239 options.hostkeyalgorithms[0] == '-' || 240 options.hostkeyalgorithms[0] == '+') 241 use_known_hosts_order = 1; 242 243 /* Expand or fill in HostkeyAlgorithms */ 244 all_key = sshkey_alg_list(0, 0, 1, ','); 245 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 246 kex_default_pk_alg(), all_key)) != 0) 247 fatal_fr(r, "kex_assemble_namelist"); 248 free(all_key); 249 250 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 251 fatal_f("kex_names_cat"); 252 myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, s); 253 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 254 myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc = 255 compat_cipher_proposal(ssh, options.ciphers); 256 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 257 myproposal[PROPOSAL_COMP_ALGS_STOC] = 258 (char *)compression_alg_list(options.compression); 259 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 260 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 261 if (use_known_hosts_order) { 262 /* Query known_hosts and prefer algorithms that appear there */ 263 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 264 compat_pkalg_proposal(ssh, 265 order_hostkeyalgs(host, hostaddr, port, cinfo)); 266 } else { 267 /* Use specified HostkeyAlgorithms exactly */ 268 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 269 compat_pkalg_proposal(ssh, options.hostkeyalgorithms); 270 } 271 272 if (options.rekey_limit || options.rekey_interval) 273 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 274 options.rekey_interval); 275 276 /* start key exchange */ 277 if ((r = kex_setup(ssh, myproposal)) != 0) 278 fatal_r(r, "kex_setup"); 279 #ifdef WITH_OPENSSL 280 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 281 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 282 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 283 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 284 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 285 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 286 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 287 # ifdef OPENSSL_HAS_ECC 288 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 289 # endif 290 #endif 291 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 292 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 293 ssh->kex->verify_host_key=&verify_host_key_callback; 294 295 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 296 297 /* remove ext-info from the KEX proposals for rekeying */ 298 myproposal[PROPOSAL_KEX_ALGS] = 299 compat_kex_proposal(ssh, options.kex_algorithms); 300 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 301 fatal_r(r, "kex_prop2buf"); 302 303 #ifdef DEBUG_KEXDH 304 /* send 1st encrypted/maced/compressed message */ 305 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 306 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 307 (r = sshpkt_send(ssh)) != 0 || 308 (r = ssh_packet_write_wait(ssh)) != 0) 309 fatal_fr(r, "send packet"); 310 #endif 311 /* Free only parts of proposal that were dynamically allocated here. */ 312 free(prop_kex); 313 free(prop_enc); 314 free(prop_hostkey); 315 } 316 317 /* 318 * Authenticate user 319 */ 320 321 typedef struct cauthctxt Authctxt; 322 typedef struct cauthmethod Authmethod; 323 typedef struct identity Identity; 324 typedef struct idlist Idlist; 325 326 struct identity { 327 TAILQ_ENTRY(identity) next; 328 int agent_fd; /* >=0 if agent supports key */ 329 struct sshkey *key; /* public/private key */ 330 char *filename; /* comment for agent-only keys */ 331 int tried; 332 int isprivate; /* key points to the private key */ 333 int userprovided; 334 }; 335 TAILQ_HEAD(idlist, identity); 336 337 struct cauthctxt { 338 const char *server_user; 339 const char *local_user; 340 const char *host; 341 const char *service; 342 struct cauthmethod *method; 343 sig_atomic_t success; 344 char *authlist; 345 #ifdef GSSAPI 346 /* gssapi */ 347 gss_OID_set gss_supported_mechs; 348 u_int mech_tried; 349 #endif 350 /* pubkey */ 351 struct idlist keys; 352 int agent_fd; 353 /* hostbased */ 354 Sensitive *sensitive; 355 char *oktypes, *ktypes; 356 const char *active_ktype; 357 /* kbd-interactive */ 358 int info_req_seen; 359 int attempt_kbdint; 360 /* password */ 361 int attempt_passwd; 362 /* generic */ 363 void *methoddata; 364 }; 365 366 struct cauthmethod { 367 char *name; /* string to compare against server's list */ 368 int (*userauth)(struct ssh *ssh); 369 void (*cleanup)(struct ssh *ssh); 370 int *enabled; /* flag in option struct that enables method */ 371 int *batch_flag; /* flag in option struct that disables method */ 372 }; 373 374 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 375 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 376 static int input_userauth_success(int, u_int32_t, struct ssh *); 377 static int input_userauth_failure(int, u_int32_t, struct ssh *); 378 static int input_userauth_banner(int, u_int32_t, struct ssh *); 379 static int input_userauth_error(int, u_int32_t, struct ssh *); 380 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 381 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 382 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 383 384 static int userauth_none(struct ssh *); 385 static int userauth_pubkey(struct ssh *); 386 static int userauth_passwd(struct ssh *); 387 static int userauth_kbdint(struct ssh *); 388 static int userauth_hostbased(struct ssh *); 389 390 #ifdef GSSAPI 391 static int userauth_gssapi(struct ssh *); 392 static void userauth_gssapi_cleanup(struct ssh *); 393 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 394 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 395 static int input_gssapi_error(int, u_int32_t, struct ssh *); 396 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 397 #endif 398 399 void userauth(struct ssh *, char *); 400 401 static void pubkey_cleanup(struct ssh *); 402 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 403 static void pubkey_prepare(struct ssh *, Authctxt *); 404 static void pubkey_reset(Authctxt *); 405 static struct sshkey *load_identity_file(Identity *); 406 407 static Authmethod *authmethod_get(char *authlist); 408 static Authmethod *authmethod_lookup(const char *name); 409 static char *authmethods_get(void); 410 411 Authmethod authmethods[] = { 412 #ifdef GSSAPI 413 {"gssapi-with-mic", 414 userauth_gssapi, 415 userauth_gssapi_cleanup, 416 &options.gss_authentication, 417 NULL}, 418 #endif 419 {"hostbased", 420 userauth_hostbased, 421 NULL, 422 &options.hostbased_authentication, 423 NULL}, 424 {"publickey", 425 userauth_pubkey, 426 NULL, 427 &options.pubkey_authentication, 428 NULL}, 429 {"keyboard-interactive", 430 userauth_kbdint, 431 NULL, 432 &options.kbd_interactive_authentication, 433 &options.batch_mode}, 434 {"password", 435 userauth_passwd, 436 NULL, 437 &options.password_authentication, 438 &options.batch_mode}, 439 {"none", 440 userauth_none, 441 NULL, 442 NULL, 443 NULL}, 444 {NULL, NULL, NULL, NULL, NULL} 445 }; 446 447 void 448 ssh_userauth2(struct ssh *ssh, const char *local_user, 449 const char *server_user, char *host, Sensitive *sensitive) 450 { 451 Authctxt authctxt; 452 int r; 453 454 if (options.preferred_authentications == NULL) 455 options.preferred_authentications = authmethods_get(); 456 457 /* setup authentication context */ 458 memset(&authctxt, 0, sizeof(authctxt)); 459 authctxt.server_user = server_user; 460 authctxt.local_user = local_user; 461 authctxt.host = host; 462 authctxt.service = "ssh-connection"; /* service name */ 463 authctxt.success = 0; 464 authctxt.method = authmethod_lookup("none"); 465 authctxt.authlist = NULL; 466 authctxt.methoddata = NULL; 467 authctxt.sensitive = sensitive; 468 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 469 authctxt.info_req_seen = 0; 470 authctxt.attempt_kbdint = 0; 471 authctxt.attempt_passwd = 0; 472 #if GSSAPI 473 authctxt.gss_supported_mechs = NULL; 474 authctxt.mech_tried = 0; 475 #endif 476 authctxt.agent_fd = -1; 477 pubkey_prepare(ssh, &authctxt); 478 if (authctxt.method == NULL) { 479 fatal_f("internal error: cannot send userauth none request"); 480 } 481 482 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 483 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 484 (r = sshpkt_send(ssh)) != 0) 485 fatal_fr(r, "send packet"); 486 487 ssh->authctxt = &authctxt; 488 ssh_dispatch_init(ssh, &input_userauth_error); 489 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 490 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 491 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 492 pubkey_cleanup(ssh); 493 ssh->authctxt = NULL; 494 495 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 496 497 if (!authctxt.success) 498 fatal("Authentication failed."); 499 if (ssh_packet_connection_is_on_socket(ssh)) { 500 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 501 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 502 authctxt.method->name); 503 } else { 504 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 505 authctxt.method->name); 506 } 507 } 508 509 /* ARGSUSED */ 510 static int 511 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 512 { 513 int r; 514 515 if (ssh_packet_remaining(ssh) > 0) { 516 char *reply; 517 518 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 519 goto out; 520 debug2("service_accept: %s", reply); 521 free(reply); 522 } else { 523 debug2("buggy server: service_accept w/o service"); 524 } 525 if ((r = sshpkt_get_end(ssh)) != 0) 526 goto out; 527 debug("SSH2_MSG_SERVICE_ACCEPT received"); 528 529 /* initial userauth request */ 530 userauth_none(ssh); 531 532 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 533 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 534 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 535 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 536 r = 0; 537 out: 538 return r; 539 } 540 541 /* ARGSUSED */ 542 static int 543 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 544 { 545 return kex_input_ext_info(type, seqnr, ssh); 546 } 547 548 void 549 userauth(struct ssh *ssh, char *authlist) 550 { 551 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 552 553 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 554 authctxt->method->cleanup(ssh); 555 556 free(authctxt->methoddata); 557 authctxt->methoddata = NULL; 558 if (authlist == NULL) { 559 authlist = authctxt->authlist; 560 } else { 561 free(authctxt->authlist); 562 authctxt->authlist = authlist; 563 } 564 for (;;) { 565 Authmethod *method = authmethod_get(authlist); 566 if (method == NULL) 567 fatal("%s@%s: Permission denied (%s).", 568 authctxt->server_user, authctxt->host, authlist); 569 authctxt->method = method; 570 571 /* reset the per method handler */ 572 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 573 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 574 575 /* and try new method */ 576 if (method->userauth(ssh) != 0) { 577 debug2("we sent a %s packet, wait for reply", method->name); 578 break; 579 } else { 580 debug2("we did not send a packet, disable method"); 581 method->enabled = NULL; 582 } 583 } 584 } 585 586 /* ARGSUSED */ 587 static int 588 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 589 { 590 fatal_f("bad message during authentication: type %d", type); 591 return 0; 592 } 593 594 /* ARGSUSED */ 595 static int 596 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 597 { 598 char *msg = NULL; 599 size_t len; 600 int r; 601 602 debug3_f("entering"); 603 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 604 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 605 goto out; 606 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 607 fmprintf(stderr, "%s", msg); 608 r = 0; 609 out: 610 free(msg); 611 return r; 612 } 613 614 /* ARGSUSED */ 615 static int 616 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 617 { 618 Authctxt *authctxt = ssh->authctxt; 619 620 if (authctxt == NULL) 621 fatal_f("no authentication context"); 622 free(authctxt->authlist); 623 authctxt->authlist = NULL; 624 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 625 authctxt->method->cleanup(ssh); 626 free(authctxt->methoddata); 627 authctxt->methoddata = NULL; 628 authctxt->success = 1; /* break out */ 629 return 0; 630 } 631 632 #if 0 633 static int 634 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 635 { 636 Authctxt *authctxt = ssh->authctxt; 637 638 if (authctxt == NULL) 639 fatal_f("no authentication context"); 640 641 fatal("Unexpected authentication success during %s.", 642 authctxt->method->name); 643 return 0; 644 } 645 #endif 646 647 /* ARGSUSED */ 648 static int 649 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 650 { 651 Authctxt *authctxt = ssh->authctxt; 652 char *authlist = NULL; 653 u_char partial; 654 655 if (authctxt == NULL) 656 fatal("input_userauth_failure: no authentication context"); 657 658 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 659 sshpkt_get_u8(ssh, &partial) != 0 || 660 sshpkt_get_end(ssh) != 0) 661 goto out; 662 663 if (partial != 0) { 664 verbose("Authenticated using \"%s\" with partial success.", 665 authctxt->method->name); 666 /* reset state */ 667 pubkey_reset(authctxt); 668 } 669 debug("Authentications that can continue: %s", authlist); 670 671 userauth(ssh, authlist); 672 authlist = NULL; 673 out: 674 free(authlist); 675 return 0; 676 } 677 678 /* 679 * Format an identity for logging including filename, key type, fingerprint 680 * and location (agent, etc.). Caller must free. 681 */ 682 static char * 683 format_identity(Identity *id) 684 { 685 char *fp = NULL, *ret = NULL; 686 const char *note = ""; 687 688 if (id->key != NULL) { 689 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 690 SSH_FP_DEFAULT); 691 } 692 if (id->key) { 693 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 694 note = " token"; 695 else if (sshkey_is_sk(id->key)) 696 note = " authenticator"; 697 } 698 xasprintf(&ret, "%s %s%s%s%s%s%s", 699 id->filename, 700 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 701 fp ? fp : "", 702 id->userprovided ? " explicit" : "", note, 703 id->agent_fd != -1 ? " agent" : ""); 704 free(fp); 705 return ret; 706 } 707 708 /* ARGSUSED */ 709 static int 710 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 711 { 712 Authctxt *authctxt = ssh->authctxt; 713 struct sshkey *key = NULL; 714 Identity *id = NULL; 715 int pktype, found = 0, sent = 0; 716 size_t blen; 717 char *pkalg = NULL, *fp = NULL, *ident = NULL; 718 u_char *pkblob = NULL; 719 int r; 720 721 if (authctxt == NULL) 722 fatal("input_userauth_pk_ok: no authentication context"); 723 724 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 725 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 726 (r = sshpkt_get_end(ssh)) != 0) 727 goto done; 728 729 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 730 debug_f("server sent unknown pkalg %s", pkalg); 731 goto done; 732 } 733 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 734 debug_r(r, "no key from blob. pkalg %s", pkalg); 735 goto done; 736 } 737 if (key->type != pktype) { 738 error("input_userauth_pk_ok: type mismatch " 739 "for decoded key (received %d, expected %d)", 740 key->type, pktype); 741 goto done; 742 } 743 744 /* 745 * search keys in the reverse order, because last candidate has been 746 * moved to the end of the queue. this also avoids confusion by 747 * duplicate keys 748 */ 749 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 750 if (sshkey_equal(key, id->key)) { 751 found = 1; 752 break; 753 } 754 } 755 if (!found || id == NULL) { 756 fp = sshkey_fingerprint(key, options.fingerprint_hash, 757 SSH_FP_DEFAULT); 758 error_f("server replied with unknown key: %s %s", 759 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 760 goto done; 761 } 762 ident = format_identity(id); 763 debug("Server accepts key: %s", ident); 764 sent = sign_and_send_pubkey(ssh, id); 765 r = 0; 766 done: 767 sshkey_free(key); 768 free(ident); 769 free(fp); 770 free(pkalg); 771 free(pkblob); 772 773 /* try another method if we did not send a packet */ 774 if (r == 0 && sent == 0) 775 userauth(ssh, NULL); 776 return r; 777 } 778 779 #ifdef GSSAPI 780 static int 781 userauth_gssapi(struct ssh *ssh) 782 { 783 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 784 Gssctxt *gssctxt = NULL; 785 OM_uint32 min; 786 int r, ok = 0; 787 gss_OID mech = NULL; 788 789 /* Try one GSSAPI method at a time, rather than sending them all at 790 * once. */ 791 792 if (authctxt->gss_supported_mechs == NULL) 793 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 794 795 /* Check to see whether the mechanism is usable before we offer it */ 796 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 797 !ok) { 798 mech = &authctxt->gss_supported_mechs-> 799 elements[authctxt->mech_tried]; 800 /* My DER encoding requires length<128 */ 801 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 802 mech, authctxt->host)) { 803 ok = 1; /* Mechanism works */ 804 } else { 805 authctxt->mech_tried++; 806 } 807 } 808 809 if (!ok || mech == NULL) 810 return 0; 811 812 authctxt->methoddata=(void *)gssctxt; 813 814 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 815 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 816 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 817 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 818 (r = sshpkt_put_u32(ssh, 1)) != 0 || 819 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 820 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 821 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 822 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 823 (r = sshpkt_send(ssh)) != 0) 824 fatal_fr(r, "send packet"); 825 826 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 827 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 828 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 829 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 830 831 authctxt->mech_tried++; /* Move along to next candidate */ 832 833 return 1; 834 } 835 836 static void 837 userauth_gssapi_cleanup(struct ssh *ssh) 838 { 839 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 840 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 841 842 ssh_gssapi_delete_ctx(&gssctxt); 843 authctxt->methoddata = NULL; 844 845 free(authctxt->gss_supported_mechs); 846 authctxt->gss_supported_mechs = NULL; 847 } 848 849 static OM_uint32 850 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 851 { 852 Authctxt *authctxt = ssh->authctxt; 853 Gssctxt *gssctxt = authctxt->methoddata; 854 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 855 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 856 gss_buffer_desc gssbuf; 857 OM_uint32 status, ms, flags; 858 int r; 859 860 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 861 recv_tok, &send_tok, &flags); 862 863 if (send_tok.length > 0) { 864 u_char type = GSS_ERROR(status) ? 865 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 866 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 867 868 if ((r = sshpkt_start(ssh, type)) != 0 || 869 (r = sshpkt_put_string(ssh, send_tok.value, 870 send_tok.length)) != 0 || 871 (r = sshpkt_send(ssh)) != 0) 872 fatal_fr(r, "send %u packet", type); 873 874 gss_release_buffer(&ms, &send_tok); 875 } 876 877 if (status == GSS_S_COMPLETE) { 878 /* send either complete or MIC, depending on mechanism */ 879 if (!(flags & GSS_C_INTEG_FLAG)) { 880 if ((r = sshpkt_start(ssh, 881 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 882 (r = sshpkt_send(ssh)) != 0) 883 fatal_fr(r, "send completion"); 884 } else { 885 struct sshbuf *b; 886 887 if ((b = sshbuf_new()) == NULL) 888 fatal_f("sshbuf_new failed"); 889 ssh_gssapi_buildmic(b, authctxt->server_user, 890 authctxt->service, "gssapi-with-mic", 891 ssh->kex->session_id); 892 893 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 894 fatal_f("sshbuf_mutable_ptr failed"); 895 gssbuf.length = sshbuf_len(b); 896 897 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 898 899 if (!GSS_ERROR(status)) { 900 if ((r = sshpkt_start(ssh, 901 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 902 (r = sshpkt_put_string(ssh, mic.value, 903 mic.length)) != 0 || 904 (r = sshpkt_send(ssh)) != 0) 905 fatal_fr(r, "send MIC"); 906 } 907 908 sshbuf_free(b); 909 gss_release_buffer(&ms, &mic); 910 } 911 } 912 913 return status; 914 } 915 916 /* ARGSUSED */ 917 static int 918 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 919 { 920 Authctxt *authctxt = ssh->authctxt; 921 Gssctxt *gssctxt; 922 size_t oidlen; 923 u_char *oidv = NULL; 924 int r; 925 926 if (authctxt == NULL) 927 fatal("input_gssapi_response: no authentication context"); 928 gssctxt = authctxt->methoddata; 929 930 /* Setup our OID */ 931 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 932 goto done; 933 934 if (oidlen <= 2 || 935 oidv[0] != SSH_GSS_OIDTYPE || 936 oidv[1] != oidlen - 2) { 937 debug("Badly encoded mechanism OID received"); 938 userauth(ssh, NULL); 939 goto ok; 940 } 941 942 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 943 fatal("Server returned different OID than expected"); 944 945 if ((r = sshpkt_get_end(ssh)) != 0) 946 goto done; 947 948 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 949 /* Start again with next method on list */ 950 debug("Trying to start again"); 951 userauth(ssh, NULL); 952 goto ok; 953 } 954 ok: 955 r = 0; 956 done: 957 free(oidv); 958 return r; 959 } 960 961 /* ARGSUSED */ 962 static int 963 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 964 { 965 Authctxt *authctxt = ssh->authctxt; 966 gss_buffer_desc recv_tok; 967 u_char *p = NULL; 968 size_t len; 969 OM_uint32 status; 970 int r; 971 972 if (authctxt == NULL) 973 fatal("input_gssapi_response: no authentication context"); 974 975 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 976 (r = sshpkt_get_end(ssh)) != 0) 977 goto out; 978 979 recv_tok.value = p; 980 recv_tok.length = len; 981 status = process_gssapi_token(ssh, &recv_tok); 982 983 /* Start again with the next method in the list */ 984 if (GSS_ERROR(status)) { 985 userauth(ssh, NULL); 986 /* ok */ 987 } 988 r = 0; 989 out: 990 free(p); 991 return r; 992 } 993 994 /* ARGSUSED */ 995 static int 996 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 997 { 998 Authctxt *authctxt = ssh->authctxt; 999 Gssctxt *gssctxt; 1000 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 1001 gss_buffer_desc recv_tok; 1002 OM_uint32 ms; 1003 u_char *p = NULL; 1004 size_t len; 1005 int r; 1006 1007 if (authctxt == NULL) 1008 fatal("input_gssapi_response: no authentication context"); 1009 gssctxt = authctxt->methoddata; 1010 1011 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1012 (r = sshpkt_get_end(ssh)) != 0) { 1013 free(p); 1014 return r; 1015 } 1016 1017 /* Stick it into GSSAPI and see what it says */ 1018 recv_tok.value = p; 1019 recv_tok.length = len; 1020 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1021 &recv_tok, &send_tok, NULL); 1022 free(p); 1023 gss_release_buffer(&ms, &send_tok); 1024 1025 /* Server will be returning a failed packet after this one */ 1026 return 0; 1027 } 1028 1029 /* ARGSUSED */ 1030 static int 1031 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1032 { 1033 char *msg = NULL; 1034 char *lang = NULL; 1035 int r; 1036 1037 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1038 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1039 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1040 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1041 goto out; 1042 r = sshpkt_get_end(ssh); 1043 debug("Server GSSAPI Error:\n%s", msg); 1044 out: 1045 free(msg); 1046 free(lang); 1047 return r; 1048 } 1049 #endif /* GSSAPI */ 1050 1051 static int 1052 userauth_none(struct ssh *ssh) 1053 { 1054 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1055 int r; 1056 1057 /* initial userauth request */ 1058 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1059 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1060 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1061 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1062 (r = sshpkt_send(ssh)) != 0) 1063 fatal_fr(r, "send packet"); 1064 return 1; 1065 } 1066 1067 static int 1068 userauth_passwd(struct ssh *ssh) 1069 { 1070 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1071 char *password, *prompt = NULL; 1072 const char *host = options.host_key_alias ? options.host_key_alias : 1073 authctxt->host; 1074 int r; 1075 1076 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1077 return 0; 1078 1079 if (authctxt->attempt_passwd != 1) 1080 error("Permission denied, please try again."); 1081 1082 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1083 password = read_passphrase(prompt, 0); 1084 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1085 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1086 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1087 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1088 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1089 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1090 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1091 (r = sshpkt_send(ssh)) != 0) 1092 fatal_fr(r, "send packet"); 1093 1094 free(prompt); 1095 if (password != NULL) 1096 freezero(password, strlen(password)); 1097 1098 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1099 &input_userauth_passwd_changereq); 1100 1101 return 1; 1102 } 1103 1104 /* 1105 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1106 */ 1107 /* ARGSUSED */ 1108 static int 1109 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1110 { 1111 Authctxt *authctxt = ssh->authctxt; 1112 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1113 char prompt[256]; 1114 const char *host; 1115 int r; 1116 1117 debug2("input_userauth_passwd_changereq"); 1118 1119 if (authctxt == NULL) 1120 fatal("input_userauth_passwd_changereq: " 1121 "no authentication context"); 1122 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1123 1124 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1125 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1126 goto out; 1127 if (strlen(info) > 0) 1128 logit("%s", info); 1129 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1130 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1131 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1132 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1133 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1134 goto out; 1135 1136 snprintf(prompt, sizeof(prompt), 1137 "Enter %.30s@%.128s's old password: ", 1138 authctxt->server_user, host); 1139 password = read_passphrase(prompt, 0); 1140 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1141 goto out; 1142 1143 freezero(password, strlen(password)); 1144 password = NULL; 1145 while (password == NULL) { 1146 snprintf(prompt, sizeof(prompt), 1147 "Enter %.30s@%.128s's new password: ", 1148 authctxt->server_user, host); 1149 password = read_passphrase(prompt, RP_ALLOW_EOF); 1150 if (password == NULL) { 1151 /* bail out */ 1152 r = 0; 1153 goto out; 1154 } 1155 snprintf(prompt, sizeof(prompt), 1156 "Retype %.30s@%.128s's new password: ", 1157 authctxt->server_user, host); 1158 retype = read_passphrase(prompt, 0); 1159 if (strcmp(password, retype) != 0) { 1160 freezero(password, strlen(password)); 1161 logit("Mismatch; try again, EOF to quit."); 1162 password = NULL; 1163 } 1164 freezero(retype, strlen(retype)); 1165 } 1166 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1167 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1168 (r = sshpkt_send(ssh)) != 0) 1169 goto out; 1170 1171 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1172 &input_userauth_passwd_changereq); 1173 r = 0; 1174 out: 1175 if (password) 1176 freezero(password, strlen(password)); 1177 free(info); 1178 free(lang); 1179 return r; 1180 } 1181 1182 /* 1183 * Select an algorithm for publickey signatures. 1184 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1185 * 1186 * Call with ssh==NULL to ignore server-sig-algs extension list and 1187 * only attempt with the key's base signature type. 1188 */ 1189 static char * 1190 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1191 { 1192 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1193 const char *server_sig_algs; 1194 1195 /* 1196 * The signature algorithm will only differ from the key algorithm 1197 * for RSA keys/certs and when the server advertises support for 1198 * newer (SHA2) algorithms. 1199 */ 1200 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1201 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1202 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1203 /* Filter base key signature alg against our configuration */ 1204 return match_list(sshkey_ssh_name(key), 1205 options.pubkey_accepted_algos, NULL); 1206 } 1207 1208 /* 1209 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1210 * fails to advertise it via SSH2_MSG_EXT_INFO. 1211 */ 1212 server_sig_algs = ssh->kex->server_sig_algs; 1213 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1214 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1215 1216 /* 1217 * For RSA keys/certs, since these might have a different sig type: 1218 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1219 * that also appears in the supported signature algorithms list from 1220 * the server. 1221 */ 1222 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1223 while ((cp = strsep(&allowed, ",")) != NULL) { 1224 if (sshkey_type_from_name(cp) != key->type) 1225 continue; 1226 tmp = match_list(sshkey_sigalg_by_name(cp), 1227 server_sig_algs, NULL); 1228 if (tmp != NULL) 1229 alg = xstrdup(cp); 1230 free(tmp); 1231 if (alg != NULL) 1232 break; 1233 } 1234 free(oallowed); 1235 return alg; 1236 } 1237 1238 static int 1239 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1240 const u_char *data, size_t datalen, u_int compat, const char *alg) 1241 { 1242 struct sshkey *sign_key = NULL, *prv = NULL; 1243 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1244 struct notifier_ctx *notifier = NULL; 1245 char *fp = NULL, *pin = NULL, *prompt = NULL; 1246 1247 *sigp = NULL; 1248 *lenp = 0; 1249 1250 /* The agent supports this key. */ 1251 if (id->key != NULL && id->agent_fd != -1) { 1252 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1253 data, datalen, alg, compat); 1254 } 1255 1256 /* 1257 * We have already loaded the private key or the private key is 1258 * stored in external hardware. 1259 */ 1260 if (id->key != NULL && 1261 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1262 sign_key = id->key; 1263 is_agent = 1; 1264 } else { 1265 /* Load the private key from the file. */ 1266 if ((prv = load_identity_file(id)) == NULL) 1267 return SSH_ERR_KEY_NOT_FOUND; 1268 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1269 error_f("private key %s contents do not match public", 1270 id->filename); 1271 r = SSH_ERR_KEY_NOT_FOUND; 1272 goto out; 1273 } 1274 sign_key = prv; 1275 } 1276 retry_pin: 1277 /* Prompt for touch for non-agent FIDO keys that request UP */ 1278 if (!is_agent && sshkey_is_sk(sign_key) && 1279 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1280 /* XXX should batch mode just skip these? */ 1281 if ((fp = sshkey_fingerprint(sign_key, 1282 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1283 fatal_f("fingerprint failed"); 1284 notifier = notify_start(options.batch_mode, 1285 "Confirm user presence for key %s %s", 1286 sshkey_type(sign_key), fp); 1287 free(fp); 1288 } 1289 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1290 alg, options.sk_provider, pin, compat)) != 0) { 1291 debug_fr(r, "sshkey_sign"); 1292 if (!retried && pin == NULL && !is_agent && 1293 sshkey_is_sk(sign_key) && 1294 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1295 notify_complete(notifier, NULL); 1296 notifier = NULL; 1297 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1298 sshkey_type(sign_key), id->filename); 1299 pin = read_passphrase(prompt, 0); 1300 retried = 1; 1301 goto retry_pin; 1302 } 1303 goto out; 1304 } 1305 1306 /* 1307 * PKCS#11 tokens may not support all signature algorithms, 1308 * so check what we get back. 1309 */ 1310 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1311 debug_fr(r, "sshkey_check_sigtype"); 1312 goto out; 1313 } 1314 /* success */ 1315 r = 0; 1316 out: 1317 free(prompt); 1318 if (pin != NULL) 1319 freezero(pin, strlen(pin)); 1320 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1321 sshkey_free(prv); 1322 return r; 1323 } 1324 1325 static int 1326 id_filename_matches(Identity *id, Identity *private_id) 1327 { 1328 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1329 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1330 size_t i, slen; 1331 1332 if (strcmp(id->filename, private_id->filename) == 0) 1333 return 1; 1334 for (i = 0; suffixes[i]; i++) { 1335 slen = strlen(suffixes[i]); 1336 if (len > slen && plen == len - slen && 1337 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1338 memcmp(id->filename, private_id->filename, plen) == 0) 1339 return 1; 1340 } 1341 return 0; 1342 } 1343 1344 static int 1345 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1346 { 1347 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1348 struct sshbuf *b = NULL; 1349 Identity *private_id, *sign_id = NULL; 1350 u_char *signature = NULL; 1351 size_t slen = 0, skip = 0; 1352 int r, fallback_sigtype, sent = 0; 1353 char *alg = NULL, *fp = NULL; 1354 const char *loc = "", *method = "publickey"; 1355 int hostbound = 0; 1356 1357 /* prefer host-bound pubkey signatures if supported by server */ 1358 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1359 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1360 hostbound = 1; 1361 method = "publickey-hostbound-v00@openssh.com"; 1362 } 1363 1364 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1365 SSH_FP_DEFAULT)) == NULL) 1366 return 0; 1367 1368 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1369 1370 /* 1371 * If the key is an certificate, try to find a matching private key 1372 * and use it to complete the signature. 1373 * If no such private key exists, fall back to trying the certificate 1374 * key itself in case it has a private half already loaded. 1375 * This will try to set sign_id to the private key that will perform 1376 * the signature. 1377 */ 1378 if (sshkey_is_cert(id->key)) { 1379 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1380 if (sshkey_equal_public(id->key, private_id->key) && 1381 id->key->type != private_id->key->type) { 1382 sign_id = private_id; 1383 break; 1384 } 1385 } 1386 /* 1387 * Exact key matches are preferred, but also allow 1388 * filename matches for non-PKCS#11/agent keys that 1389 * didn't load public keys. This supports the case 1390 * of keeping just a private key file and public 1391 * certificate on disk. 1392 */ 1393 if (sign_id == NULL && 1394 !id->isprivate && id->agent_fd == -1 && 1395 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1396 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1397 if (private_id->key == NULL && 1398 id_filename_matches(id, private_id)) { 1399 sign_id = private_id; 1400 break; 1401 } 1402 } 1403 } 1404 if (sign_id != NULL) { 1405 debug2_f("using private key \"%s\"%s for " 1406 "certificate", sign_id->filename, 1407 sign_id->agent_fd != -1 ? " from agent" : ""); 1408 } else { 1409 debug_f("no separate private key for certificate " 1410 "\"%s\"", id->filename); 1411 } 1412 } 1413 1414 /* 1415 * If the above didn't select another identity to do the signing 1416 * then default to the one we started with. 1417 */ 1418 if (sign_id == NULL) 1419 sign_id = id; 1420 1421 /* assemble and sign data */ 1422 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1423 free(alg); 1424 slen = 0; 1425 signature = NULL; 1426 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1427 id->key)) == NULL) { 1428 error_f("no mutual signature supported"); 1429 goto out; 1430 } 1431 debug3_f("signing using %s %s", alg, fp); 1432 1433 sshbuf_free(b); 1434 if ((b = sshbuf_new()) == NULL) 1435 fatal_f("sshbuf_new failed"); 1436 if (ssh->compat & SSH_OLD_SESSIONID) { 1437 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1438 fatal_fr(r, "sshbuf_putb"); 1439 } else { 1440 if ((r = sshbuf_put_stringb(b, 1441 ssh->kex->session_id)) != 0) 1442 fatal_fr(r, "sshbuf_put_stringb"); 1443 } 1444 skip = sshbuf_len(b); 1445 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1446 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1447 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1448 (r = sshbuf_put_cstring(b, method)) != 0 || 1449 (r = sshbuf_put_u8(b, 1)) != 0 || 1450 (r = sshbuf_put_cstring(b, alg)) != 0 || 1451 (r = sshkey_puts(id->key, b)) != 0) { 1452 fatal_fr(r, "assemble signed data"); 1453 } 1454 if (hostbound) { 1455 if (ssh->kex->initial_hostkey == NULL) { 1456 fatal_f("internal error: initial hostkey " 1457 "not recorded"); 1458 } 1459 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1460 fatal_fr(r, "assemble %s hostkey", method); 1461 } 1462 /* generate signature */ 1463 r = identity_sign(sign_id, &signature, &slen, 1464 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1465 if (r == 0) 1466 break; 1467 else if (r == SSH_ERR_KEY_NOT_FOUND) 1468 goto out; /* soft failure */ 1469 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1470 !fallback_sigtype) { 1471 if (sign_id->agent_fd != -1) 1472 loc = "agent "; 1473 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1474 loc = "token "; 1475 logit("%skey %s %s returned incorrect signature type", 1476 loc, sshkey_type(id->key), fp); 1477 continue; 1478 } 1479 error_fr(r, "signing failed for %s \"%s\"%s", 1480 sshkey_type(sign_id->key), sign_id->filename, 1481 id->agent_fd != -1 ? " from agent" : ""); 1482 goto out; 1483 } 1484 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1485 fatal_f("no signature"); 1486 1487 /* append signature */ 1488 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1489 fatal_fr(r, "append signature"); 1490 1491 #ifdef DEBUG_PK 1492 sshbuf_dump(b, stderr); 1493 #endif 1494 /* skip session id and packet type */ 1495 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1496 fatal_fr(r, "consume"); 1497 1498 /* put remaining data from buffer into packet */ 1499 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1500 (r = sshpkt_putb(ssh, b)) != 0 || 1501 (r = sshpkt_send(ssh)) != 0) 1502 fatal_fr(r, "enqueue request"); 1503 1504 /* success */ 1505 sent = 1; 1506 1507 out: 1508 free(fp); 1509 free(alg); 1510 sshbuf_free(b); 1511 freezero(signature, slen); 1512 return sent; 1513 } 1514 1515 static int 1516 send_pubkey_test(struct ssh *ssh, Identity *id) 1517 { 1518 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1519 u_char *blob = NULL; 1520 char *alg = NULL; 1521 size_t bloblen; 1522 u_int have_sig = 0; 1523 int sent = 0, r; 1524 1525 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1526 debug_f("no mutual signature algorithm"); 1527 goto out; 1528 } 1529 1530 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1531 /* we cannot handle this key */ 1532 debug3_f("cannot handle key"); 1533 goto out; 1534 } 1535 /* register callback for USERAUTH_PK_OK message */ 1536 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1537 1538 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1539 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1540 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1541 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1542 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1543 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1544 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1545 (r = sshpkt_send(ssh)) != 0) 1546 fatal_fr(r, "send packet"); 1547 sent = 1; 1548 1549 out: 1550 free(alg); 1551 free(blob); 1552 return sent; 1553 } 1554 1555 static struct sshkey * 1556 load_identity_file(Identity *id) 1557 { 1558 struct sshkey *private = NULL; 1559 char prompt[300], *passphrase, *comment; 1560 int r, quit = 0, i; 1561 struct stat st; 1562 1563 if (stat(id->filename, &st) == -1) { 1564 do_log2(id->userprovided ? 1565 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1566 "no such identity: %s: %s", id->filename, strerror(errno)); 1567 return NULL; 1568 } 1569 snprintf(prompt, sizeof prompt, 1570 "Enter passphrase for key '%.100s': ", id->filename); 1571 for (i = 0; i <= options.number_of_password_prompts; i++) { 1572 if (i == 0) 1573 passphrase = ""; 1574 else { 1575 passphrase = read_passphrase(prompt, 0); 1576 if (*passphrase == '\0') { 1577 debug2("no passphrase given, try next key"); 1578 free(passphrase); 1579 break; 1580 } 1581 } 1582 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1583 passphrase, &private, &comment))) { 1584 case 0: 1585 break; 1586 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1587 if (options.batch_mode) { 1588 quit = 1; 1589 break; 1590 } 1591 if (i != 0) 1592 debug2("bad passphrase given, try again..."); 1593 break; 1594 case SSH_ERR_SYSTEM_ERROR: 1595 if (errno == ENOENT) { 1596 debug2_r(r, "Load key \"%s\"", id->filename); 1597 quit = 1; 1598 break; 1599 } 1600 /* FALLTHROUGH */ 1601 default: 1602 error_r(r, "Load key \"%s\"", id->filename); 1603 quit = 1; 1604 break; 1605 } 1606 if (private != NULL && sshkey_is_sk(private) && 1607 options.sk_provider == NULL) { 1608 debug("key \"%s\" is an authenticator-hosted key, " 1609 "but no provider specified", id->filename); 1610 sshkey_free(private); 1611 private = NULL; 1612 quit = 1; 1613 } 1614 if (!quit && (r = sshkey_check_rsa_length(private, 1615 options.required_rsa_size)) != 0) { 1616 debug_fr(r, "Skipping key %s", id->filename); 1617 sshkey_free(private); 1618 private = NULL; 1619 quit = 1; 1620 } 1621 if (!quit && private != NULL && id->agent_fd == -1 && 1622 !(id->key && id->isprivate)) 1623 maybe_add_key_to_agent(id->filename, private, comment, 1624 passphrase); 1625 if (i > 0) 1626 freezero(passphrase, strlen(passphrase)); 1627 free(comment); 1628 if (private != NULL || quit) 1629 break; 1630 } 1631 return private; 1632 } 1633 1634 static int 1635 key_type_allowed_by_config(struct sshkey *key) 1636 { 1637 if (match_pattern_list(sshkey_ssh_name(key), 1638 options.pubkey_accepted_algos, 0) == 1) 1639 return 1; 1640 1641 /* RSA keys/certs might be allowed by alternate signature types */ 1642 switch (key->type) { 1643 case KEY_RSA: 1644 if (match_pattern_list("rsa-sha2-512", 1645 options.pubkey_accepted_algos, 0) == 1) 1646 return 1; 1647 if (match_pattern_list("rsa-sha2-256", 1648 options.pubkey_accepted_algos, 0) == 1) 1649 return 1; 1650 break; 1651 case KEY_RSA_CERT: 1652 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1653 options.pubkey_accepted_algos, 0) == 1) 1654 return 1; 1655 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1656 options.pubkey_accepted_algos, 0) == 1) 1657 return 1; 1658 break; 1659 } 1660 return 0; 1661 } 1662 1663 /* obtain a list of keys from the agent */ 1664 static int 1665 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1666 struct ssh_identitylist **idlistp) 1667 { 1668 int r, agent_fd; 1669 struct ssh_identitylist *idlist; 1670 1671 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1672 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1673 debug_fr(r, "ssh_get_authentication_socket"); 1674 return r; 1675 } 1676 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1677 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1678 debug_f("bound agent to hostkey"); 1679 else 1680 debug2_fr(r, "ssh_agent_bind_hostkey"); 1681 1682 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1683 debug_fr(r, "ssh_fetch_identitylist"); 1684 close(agent_fd); 1685 return r; 1686 } 1687 /* success */ 1688 *agent_fdp = agent_fd; 1689 *idlistp = idlist; 1690 debug_f("agent returned %zu keys", idlist->nkeys); 1691 return 0; 1692 } 1693 1694 /* 1695 * try keys in the following order: 1696 * 1. certificates listed in the config file 1697 * 2. other input certificates 1698 * 3. agent keys that are found in the config file 1699 * 4. other agent keys 1700 * 5. keys that are only listed in the config file 1701 */ 1702 static void 1703 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1704 { 1705 struct identity *id, *id2, *tmp; 1706 struct idlist agent, files, *preferred; 1707 struct sshkey *key; 1708 int agent_fd = -1, i, r, found; 1709 size_t j; 1710 struct ssh_identitylist *idlist; 1711 char *ident; 1712 1713 TAILQ_INIT(&agent); /* keys from the agent */ 1714 TAILQ_INIT(&files); /* keys from the config file */ 1715 preferred = &authctxt->keys; 1716 TAILQ_INIT(preferred); /* preferred order of keys */ 1717 1718 /* list of keys stored in the filesystem and PKCS#11 */ 1719 for (i = 0; i < options.num_identity_files; i++) { 1720 key = options.identity_keys[i]; 1721 if (key && key->cert && 1722 key->cert->type != SSH2_CERT_TYPE_USER) { 1723 debug_f("ignoring certificate %s: not a user " 1724 "certificate", options.identity_files[i]); 1725 continue; 1726 } 1727 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1728 debug_f("ignoring authenticator-hosted key %s as no " 1729 "SecurityKeyProvider has been specified", 1730 options.identity_files[i]); 1731 continue; 1732 } 1733 options.identity_keys[i] = NULL; 1734 id = xcalloc(1, sizeof(*id)); 1735 id->agent_fd = -1; 1736 id->key = key; 1737 id->filename = xstrdup(options.identity_files[i]); 1738 id->userprovided = options.identity_file_userprovided[i]; 1739 TAILQ_INSERT_TAIL(&files, id, next); 1740 } 1741 /* list of certificates specified by user */ 1742 for (i = 0; i < options.num_certificate_files; i++) { 1743 key = options.certificates[i]; 1744 if (!sshkey_is_cert(key) || key->cert == NULL || 1745 key->cert->type != SSH2_CERT_TYPE_USER) { 1746 debug_f("ignoring certificate %s: not a user " 1747 "certificate", options.identity_files[i]); 1748 continue; 1749 } 1750 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1751 debug_f("ignoring authenticator-hosted key " 1752 "certificate %s as no " 1753 "SecurityKeyProvider has been specified", 1754 options.identity_files[i]); 1755 continue; 1756 } 1757 id = xcalloc(1, sizeof(*id)); 1758 id->agent_fd = -1; 1759 id->key = key; 1760 id->filename = xstrdup(options.certificate_files[i]); 1761 id->userprovided = options.certificate_file_userprovided[i]; 1762 TAILQ_INSERT_TAIL(preferred, id, next); 1763 } 1764 /* list of keys supported by the agent */ 1765 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1766 for (j = 0; j < idlist->nkeys; j++) { 1767 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1768 options.required_rsa_size)) != 0) { 1769 debug_fr(r, "ignoring %s agent key", 1770 sshkey_ssh_name(idlist->keys[j])); 1771 continue; 1772 } 1773 found = 0; 1774 TAILQ_FOREACH(id, &files, next) { 1775 /* 1776 * agent keys from the config file are 1777 * preferred 1778 */ 1779 if (sshkey_equal(idlist->keys[j], id->key)) { 1780 TAILQ_REMOVE(&files, id, next); 1781 TAILQ_INSERT_TAIL(preferred, id, next); 1782 id->agent_fd = agent_fd; 1783 found = 1; 1784 break; 1785 } 1786 } 1787 if (!found && !options.identities_only) { 1788 id = xcalloc(1, sizeof(*id)); 1789 /* XXX "steals" key/comment from idlist */ 1790 id->key = idlist->keys[j]; 1791 id->filename = idlist->comments[j]; 1792 idlist->keys[j] = NULL; 1793 idlist->comments[j] = NULL; 1794 id->agent_fd = agent_fd; 1795 TAILQ_INSERT_TAIL(&agent, id, next); 1796 } 1797 } 1798 ssh_free_identitylist(idlist); 1799 /* append remaining agent keys */ 1800 TAILQ_CONCAT(preferred, &agent, next); 1801 authctxt->agent_fd = agent_fd; 1802 } 1803 /* Prefer PKCS11 keys that are explicitly listed */ 1804 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1805 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1806 continue; 1807 found = 0; 1808 TAILQ_FOREACH(id2, &files, next) { 1809 if (id2->key == NULL || 1810 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1811 continue; 1812 if (sshkey_equal(id->key, id2->key)) { 1813 TAILQ_REMOVE(&files, id, next); 1814 TAILQ_INSERT_TAIL(preferred, id, next); 1815 found = 1; 1816 break; 1817 } 1818 } 1819 /* If IdentitiesOnly set and key not found then don't use it */ 1820 if (!found && options.identities_only) { 1821 TAILQ_REMOVE(&files, id, next); 1822 freezero(id, sizeof(*id)); 1823 } 1824 } 1825 /* append remaining keys from the config file */ 1826 TAILQ_CONCAT(preferred, &files, next); 1827 /* finally, filter by PubkeyAcceptedAlgorithms */ 1828 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1829 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1830 debug("Skipping %s key %s - " 1831 "corresponding algo not in PubkeyAcceptedAlgorithms", 1832 sshkey_ssh_name(id->key), id->filename); 1833 TAILQ_REMOVE(preferred, id, next); 1834 sshkey_free(id->key); 1835 free(id->filename); 1836 memset(id, 0, sizeof(*id)); 1837 continue; 1838 } 1839 } 1840 /* List the keys we plan on using */ 1841 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1842 ident = format_identity(id); 1843 debug("Will attempt key: %s", ident); 1844 free(ident); 1845 } 1846 debug2_f("done"); 1847 } 1848 1849 static void 1850 pubkey_cleanup(struct ssh *ssh) 1851 { 1852 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1853 Identity *id; 1854 1855 if (authctxt->agent_fd != -1) { 1856 ssh_close_authentication_socket(authctxt->agent_fd); 1857 authctxt->agent_fd = -1; 1858 } 1859 for (id = TAILQ_FIRST(&authctxt->keys); id; 1860 id = TAILQ_FIRST(&authctxt->keys)) { 1861 TAILQ_REMOVE(&authctxt->keys, id, next); 1862 sshkey_free(id->key); 1863 free(id->filename); 1864 free(id); 1865 } 1866 } 1867 1868 static void 1869 pubkey_reset(Authctxt *authctxt) 1870 { 1871 Identity *id; 1872 1873 TAILQ_FOREACH(id, &authctxt->keys, next) 1874 id->tried = 0; 1875 } 1876 1877 static int 1878 try_identity(struct ssh *ssh, Identity *id) 1879 { 1880 if (!id->key) 1881 return (0); 1882 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1883 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 1884 debug("Skipped %s key %s for RSA/MD5 server", 1885 sshkey_type(id->key), id->filename); 1886 return (0); 1887 } 1888 return 1; 1889 } 1890 1891 static int 1892 userauth_pubkey(struct ssh *ssh) 1893 { 1894 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1895 Identity *id; 1896 int sent = 0; 1897 char *ident; 1898 1899 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1900 if (id->tried++) 1901 return (0); 1902 /* move key to the end of the queue */ 1903 TAILQ_REMOVE(&authctxt->keys, id, next); 1904 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1905 /* 1906 * send a test message if we have the public key. for 1907 * encrypted keys we cannot do this and have to load the 1908 * private key instead 1909 */ 1910 if (id->key != NULL) { 1911 if (try_identity(ssh, id)) { 1912 ident = format_identity(id); 1913 debug("Offering public key: %s", ident); 1914 free(ident); 1915 sent = send_pubkey_test(ssh, id); 1916 } 1917 } else { 1918 debug("Trying private key: %s", id->filename); 1919 id->key = load_identity_file(id); 1920 if (id->key != NULL) { 1921 if (try_identity(ssh, id)) { 1922 id->isprivate = 1; 1923 sent = sign_and_send_pubkey(ssh, id); 1924 } 1925 sshkey_free(id->key); 1926 id->key = NULL; 1927 id->isprivate = 0; 1928 } 1929 } 1930 if (sent) 1931 return (sent); 1932 } 1933 return (0); 1934 } 1935 1936 /* 1937 * Send userauth request message specifying keyboard-interactive method. 1938 */ 1939 static int 1940 userauth_kbdint(struct ssh *ssh) 1941 { 1942 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1943 int r; 1944 1945 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1946 return 0; 1947 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1948 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1949 debug3("userauth_kbdint: disable: no info_req_seen"); 1950 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1951 return 0; 1952 } 1953 1954 debug2("userauth_kbdint"); 1955 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1956 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1957 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1958 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1959 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1960 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1961 options.kbd_interactive_devices : "")) != 0 || 1962 (r = sshpkt_send(ssh)) != 0) 1963 fatal_fr(r, "send packet"); 1964 1965 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1966 return 1; 1967 } 1968 1969 /* 1970 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1971 */ 1972 static int 1973 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1974 { 1975 Authctxt *authctxt = ssh->authctxt; 1976 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1977 char *display_prompt = NULL, *response = NULL; 1978 u_char echo = 0; 1979 u_int num_prompts, i; 1980 int r; 1981 1982 debug2_f("entering"); 1983 1984 if (authctxt == NULL) 1985 fatal_f("no authentication context"); 1986 1987 authctxt->info_req_seen = 1; 1988 1989 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1990 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1991 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1992 goto out; 1993 if (strlen(name) > 0) 1994 logit("%s", name); 1995 if (strlen(inst) > 0) 1996 logit("%s", inst); 1997 1998 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1999 goto out; 2000 /* 2001 * Begin to build info response packet based on prompts requested. 2002 * We commit to providing the correct number of responses, so if 2003 * further on we run into a problem that prevents this, we have to 2004 * be sure and clean this up and send a correct error response. 2005 */ 2006 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 2007 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 2008 goto out; 2009 2010 debug2_f("num_prompts %d", num_prompts); 2011 for (i = 0; i < num_prompts; i++) { 2012 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 2013 (r = sshpkt_get_u8(ssh, &echo)) != 0) 2014 goto out; 2015 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 2016 authctxt->server_user, options.host_key_alias ? 2017 options.host_key_alias : authctxt->host, prompt) == -1) 2018 fatal_f("asmprintf failed"); 2019 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 2020 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 2021 goto out; 2022 freezero(response, strlen(response)); 2023 free(prompt); 2024 free(display_prompt); 2025 display_prompt = response = prompt = NULL; 2026 } 2027 /* done with parsing incoming message. */ 2028 if ((r = sshpkt_get_end(ssh)) != 0 || 2029 (r = sshpkt_add_padding(ssh, 64)) != 0) 2030 goto out; 2031 r = sshpkt_send(ssh); 2032 out: 2033 if (response) 2034 freezero(response, strlen(response)); 2035 free(prompt); 2036 free(display_prompt); 2037 free(name); 2038 free(inst); 2039 free(lang); 2040 return r; 2041 } 2042 2043 static int 2044 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2045 const u_char *data, size_t datalen) 2046 { 2047 struct sshbuf *b; 2048 struct stat st; 2049 pid_t pid; 2050 int r, to[2], from[2], status; 2051 int sock = ssh_packet_get_connection_in(ssh); 2052 u_char rversion = 0, version = 2; 2053 void (*osigchld)(int); 2054 2055 *sigp = NULL; 2056 *lenp = 0; 2057 2058 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2059 error_f("not installed: %s", strerror(errno)); 2060 return -1; 2061 } 2062 if (fflush(stdout) != 0) { 2063 error_f("fflush: %s", strerror(errno)); 2064 return -1; 2065 } 2066 if (pipe(to) == -1) { 2067 error_f("pipe: %s", strerror(errno)); 2068 return -1; 2069 } 2070 if (pipe(from) == -1) { 2071 error_f("pipe: %s", strerror(errno)); 2072 return -1; 2073 } 2074 if ((pid = fork()) == -1) { 2075 error_f("fork: %s", strerror(errno)); 2076 return -1; 2077 } 2078 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2079 if (pid == 0) { 2080 close(from[0]); 2081 if (dup2(from[1], STDOUT_FILENO) == -1) 2082 fatal_f("dup2: %s", strerror(errno)); 2083 close(to[1]); 2084 if (dup2(to[0], STDIN_FILENO) == -1) 2085 fatal_f("dup2: %s", strerror(errno)); 2086 close(from[1]); 2087 close(to[0]); 2088 2089 if (dup2(sock, STDERR_FILENO + 1) == -1) 2090 fatal_f("dup2: %s", strerror(errno)); 2091 sock = STDERR_FILENO + 1; 2092 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2093 closefrom(sock + 1); 2094 2095 debug3_f("[child] pid=%ld, exec %s", 2096 (long)getpid(), _PATH_SSH_KEY_SIGN); 2097 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2098 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2099 strerror(errno)); 2100 } 2101 close(from[1]); 2102 close(to[0]); 2103 sock = STDERR_FILENO + 1; 2104 2105 if ((b = sshbuf_new()) == NULL) 2106 fatal_f("sshbuf_new failed"); 2107 /* send # of sock, data to be signed */ 2108 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2109 (r = sshbuf_put_string(b, data, datalen)) != 0) 2110 fatal_fr(r, "buffer error"); 2111 if (ssh_msg_send(to[1], version, b) == -1) 2112 fatal_f("couldn't send request"); 2113 sshbuf_reset(b); 2114 r = ssh_msg_recv(from[0], b); 2115 close(from[0]); 2116 close(to[1]); 2117 if (r < 0) { 2118 error_f("no reply"); 2119 goto fail; 2120 } 2121 2122 errno = 0; 2123 while (waitpid(pid, &status, 0) == -1) { 2124 if (errno != EINTR) { 2125 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2126 goto fail; 2127 } 2128 } 2129 if (!WIFEXITED(status)) { 2130 error_f("exited abnormally"); 2131 goto fail; 2132 } 2133 if (WEXITSTATUS(status) != 0) { 2134 error_f("exited with status %d", WEXITSTATUS(status)); 2135 goto fail; 2136 } 2137 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2138 error_fr(r, "buffer error"); 2139 goto fail; 2140 } 2141 if (rversion != version) { 2142 error_f("bad version"); 2143 goto fail; 2144 } 2145 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2146 error_fr(r, "buffer error"); 2147 fail: 2148 ssh_signal(SIGCHLD, osigchld); 2149 sshbuf_free(b); 2150 return -1; 2151 } 2152 ssh_signal(SIGCHLD, osigchld); 2153 sshbuf_free(b); 2154 2155 return 0; 2156 } 2157 2158 static int 2159 userauth_hostbased(struct ssh *ssh) 2160 { 2161 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2162 struct sshkey *private = NULL; 2163 struct sshbuf *b = NULL; 2164 u_char *sig = NULL, *keyblob = NULL; 2165 char *fp = NULL, *chost = NULL, *lname = NULL; 2166 size_t siglen = 0, keylen = 0; 2167 int i, r, success = 0; 2168 2169 if (authctxt->ktypes == NULL) { 2170 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2171 authctxt->ktypes = authctxt->oktypes; 2172 } 2173 2174 /* 2175 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2176 * trying each hostkey that matches the type in turn. 2177 */ 2178 for (;;) { 2179 if (authctxt->active_ktype == NULL) 2180 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2181 if (authctxt->active_ktype == NULL || 2182 *authctxt->active_ktype == '\0') 2183 break; 2184 debug3_f("trying key type %s", authctxt->active_ktype); 2185 2186 /* check for a useful key */ 2187 private = NULL; 2188 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2189 if (authctxt->sensitive->keys[i] == NULL || 2190 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2191 continue; 2192 if (!sshkey_match_keyname_to_sigalgs( 2193 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2194 authctxt->active_ktype)) 2195 continue; 2196 /* we take and free the key */ 2197 private = authctxt->sensitive->keys[i]; 2198 authctxt->sensitive->keys[i] = NULL; 2199 break; 2200 } 2201 /* Found one */ 2202 if (private != NULL) 2203 break; 2204 /* No more keys of this type; advance */ 2205 authctxt->active_ktype = NULL; 2206 } 2207 if (private == NULL) { 2208 free(authctxt->oktypes); 2209 authctxt->oktypes = authctxt->ktypes = NULL; 2210 authctxt->active_ktype = NULL; 2211 debug("No more client hostkeys for hostbased authentication."); 2212 goto out; 2213 } 2214 2215 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2216 SSH_FP_DEFAULT)) == NULL) { 2217 error_f("sshkey_fingerprint failed"); 2218 goto out; 2219 } 2220 debug_f("trying hostkey %s %s using sigalg %s", 2221 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2222 2223 /* figure out a name for the client host */ 2224 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2225 if (lname == NULL) { 2226 error_f("cannot get local ipaddr/name"); 2227 goto out; 2228 } 2229 2230 /* XXX sshbuf_put_stringf? */ 2231 xasprintf(&chost, "%s.", lname); 2232 debug2_f("chost %s", chost); 2233 2234 /* construct data */ 2235 if ((b = sshbuf_new()) == NULL) { 2236 error_f("sshbuf_new failed"); 2237 goto out; 2238 } 2239 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2240 error_fr(r, "sshkey_to_blob"); 2241 goto out; 2242 } 2243 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2244 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2245 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2246 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2247 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2248 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2249 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2250 (r = sshbuf_put_cstring(b, chost)) != 0 || 2251 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2252 error_fr(r, "buffer error"); 2253 goto out; 2254 } 2255 2256 #ifdef DEBUG_PK 2257 sshbuf_dump(b, stderr); 2258 #endif 2259 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2260 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2261 error("sign using hostkey %s %s failed", 2262 sshkey_ssh_name(private), fp); 2263 goto out; 2264 } 2265 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2266 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2267 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2268 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2269 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2270 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2271 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2272 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2273 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2274 (r = sshpkt_send(ssh)) != 0) { 2275 error_fr(r, "packet error"); 2276 goto out; 2277 } 2278 success = 1; 2279 2280 out: 2281 if (sig != NULL) 2282 freezero(sig, siglen); 2283 free(keyblob); 2284 free(lname); 2285 free(fp); 2286 free(chost); 2287 sshkey_free(private); 2288 sshbuf_free(b); 2289 2290 return success; 2291 } 2292 2293 /* find auth method */ 2294 2295 /* 2296 * given auth method name, if configurable options permit this method fill 2297 * in auth_ident field and return true, otherwise return false. 2298 */ 2299 static int 2300 authmethod_is_enabled(Authmethod *method) 2301 { 2302 if (method == NULL) 2303 return 0; 2304 /* return false if options indicate this method is disabled */ 2305 if (method->enabled == NULL || *method->enabled == 0) 2306 return 0; 2307 /* return false if batch mode is enabled but method needs interactive mode */ 2308 if (method->batch_flag != NULL && *method->batch_flag != 0) 2309 return 0; 2310 return 1; 2311 } 2312 2313 static Authmethod * 2314 authmethod_lookup(const char *name) 2315 { 2316 Authmethod *method = NULL; 2317 if (name != NULL) 2318 for (method = authmethods; method->name != NULL; method++) 2319 if (strcmp(name, method->name) == 0) 2320 return method; 2321 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2322 return NULL; 2323 } 2324 2325 /* XXX internal state */ 2326 static Authmethod *current = NULL; 2327 static char *supported = NULL; 2328 static char *preferred = NULL; 2329 2330 /* 2331 * Given the authentication method list sent by the server, return the 2332 * next method we should try. If the server initially sends a nil list, 2333 * use a built-in default list. 2334 */ 2335 static Authmethod * 2336 authmethod_get(char *authlist) 2337 { 2338 char *name = NULL; 2339 u_int next; 2340 2341 /* Use a suitable default if we're passed a nil list. */ 2342 if (authlist == NULL || strlen(authlist) == 0) 2343 authlist = options.preferred_authentications; 2344 2345 if (supported == NULL || strcmp(authlist, supported) != 0) { 2346 debug3("start over, passed a different list %s", authlist); 2347 free(supported); 2348 supported = xstrdup(authlist); 2349 preferred = options.preferred_authentications; 2350 debug3("preferred %s", preferred); 2351 current = NULL; 2352 } else if (current != NULL && authmethod_is_enabled(current)) 2353 return current; 2354 2355 for (;;) { 2356 if ((name = match_list(preferred, supported, &next)) == NULL) { 2357 debug("No more authentication methods to try."); 2358 current = NULL; 2359 return NULL; 2360 } 2361 preferred += next; 2362 debug3("authmethod_lookup %s", name); 2363 debug3("remaining preferred: %s", preferred); 2364 if ((current = authmethod_lookup(name)) != NULL && 2365 authmethod_is_enabled(current)) { 2366 debug3("authmethod_is_enabled %s", name); 2367 debug("Next authentication method: %s", name); 2368 free(name); 2369 return current; 2370 } 2371 free(name); 2372 } 2373 } 2374 2375 static char * 2376 authmethods_get(void) 2377 { 2378 Authmethod *method = NULL; 2379 struct sshbuf *b; 2380 char *list; 2381 int r; 2382 2383 if ((b = sshbuf_new()) == NULL) 2384 fatal_f("sshbuf_new failed"); 2385 for (method = authmethods; method->name != NULL; method++) { 2386 if (authmethod_is_enabled(method)) { 2387 if ((r = sshbuf_putf(b, "%s%s", 2388 sshbuf_len(b) ? "," : "", method->name)) != 0) 2389 fatal_fr(r, "buffer error"); 2390 } 2391 } 2392 if ((list = sshbuf_dup_string(b)) == NULL) 2393 fatal_f("sshbuf_dup_string failed"); 2394 sshbuf_free(b); 2395 return list; 2396 } 2397