sshconnect2.c revision 1.1.1.24
1 /* $OpenBSD: sshconnect2.c,v 1.326 2020/09/18 05:23:03 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 <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <stdarg.h> 39 #include <signal.h> 40 #include <pwd.h> 41 #include <unistd.h> 42 #include <vis.h> 43 44 #include "xmalloc.h" 45 #include "ssh.h" 46 #include "ssh2.h" 47 #include "sshbuf.h" 48 #include "packet.h" 49 #include "compat.h" 50 #include "cipher.h" 51 #include "sshkey.h" 52 #include "kex.h" 53 #include "myproposal.h" 54 #include "sshconnect.h" 55 #include "authfile.h" 56 #include "dh.h" 57 #include "authfd.h" 58 #include "log.h" 59 #include "misc.h" 60 #include "readconf.h" 61 #include "match.h" 62 #include "dispatch.h" 63 #include "canohost.h" 64 #include "msg.h" 65 #include "pathnames.h" 66 #include "uidswap.h" 67 #include "hostfile.h" 68 #include "ssherr.h" 69 #include "utf8.h" 70 #include "ssh-sk.h" 71 #include "sk-api.h" 72 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 77 /* import */ 78 extern char *client_version_string; 79 extern char *server_version_string; 80 extern Options options; 81 82 /* 83 * SSH2 key exchange 84 */ 85 86 u_char *session_id2 = NULL; 87 u_int session_id2_len = 0; 88 89 char *xxx_host; 90 struct sockaddr *xxx_hostaddr; 91 92 static int 93 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 94 { 95 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 96 fatal("Host key verification failed."); 97 return 0; 98 } 99 100 /* Returns the first item from a comma-separated algorithm list */ 101 static char * 102 first_alg(const char *algs) 103 { 104 char *ret, *cp; 105 106 ret = xstrdup(algs); 107 if ((cp = strchr(ret, ',')) != NULL) 108 *cp = '\0'; 109 return ret; 110 } 111 112 static char * 113 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 114 { 115 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 116 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 117 size_t maxlen; 118 struct hostkeys *hostkeys = NULL; 119 int ktype; 120 u_int i; 121 122 /* Find all hostkeys for this hostname */ 123 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 124 hostkeys = init_hostkeys(); 125 for (i = 0; i < options.num_user_hostfiles; i++) 126 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 127 for (i = 0; i < options.num_system_hostfiles; i++) 128 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 129 130 /* 131 * If a plain public key exists that matches the type of the best 132 * preference HostkeyAlgorithms, then use the whole list as is. 133 * Note that we ignore whether the best preference algorithm is a 134 * certificate type, as sshconnect.c will downgrade certs to 135 * plain keys if necessary. 136 */ 137 best = first_alg(options.hostkeyalgorithms); 138 if (lookup_key_in_hostkeys_by_type(hostkeys, 139 sshkey_type_plain(sshkey_type_from_name(best)), NULL)) { 140 debug3("%s: have matching best-preference key type %s, " 141 "using HostkeyAlgorithms verbatim", __func__, best); 142 ret = xstrdup(options.hostkeyalgorithms); 143 goto out; 144 } 145 146 /* 147 * Otherwise, prefer the host key algorithms that match known keys 148 * while keeping the ordering of HostkeyAlgorithms as much as possible. 149 */ 150 oavail = avail = xstrdup(options.hostkeyalgorithms); 151 maxlen = strlen(avail) + 1; 152 first = xmalloc(maxlen); 153 last = xmalloc(maxlen); 154 *first = *last = '\0'; 155 156 #define ALG_APPEND(to, from) \ 157 do { \ 158 if (*to != '\0') \ 159 strlcat(to, ",", maxlen); \ 160 strlcat(to, from, maxlen); \ 161 } while (0) 162 163 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 164 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 165 fatal("%s: unknown alg %s", __func__, alg); 166 /* 167 * If we have a @cert-authority marker in known_hosts then 168 * prefer all certificate algorithms. 169 */ 170 if (sshkey_type_is_cert(ktype) && 171 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 172 ALG_APPEND(first, alg); 173 continue; 174 } 175 /* If the key appears in known_hosts then prefer it */ 176 if (lookup_key_in_hostkeys_by_type(hostkeys, 177 sshkey_type_plain(ktype), NULL)) { 178 ALG_APPEND(first, alg); 179 continue; 180 } 181 /* Otherwise, put it last */ 182 ALG_APPEND(last, alg); 183 } 184 #undef ALG_APPEND 185 xasprintf(&ret, "%s%s%s", first, 186 (*first == '\0' || *last == '\0') ? "" : ",", last); 187 if (*first != '\0') 188 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 189 190 out: 191 free(best); 192 free(first); 193 free(last); 194 free(hostname); 195 free(oavail); 196 free_hostkeys(hostkeys); 197 198 return ret; 199 } 200 201 void 202 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 203 { 204 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 205 char *s, *all_key; 206 int r, use_known_hosts_order = 0; 207 208 xxx_host = host; 209 xxx_hostaddr = hostaddr; 210 211 /* 212 * If the user has not specified HostkeyAlgorithms, or has only 213 * appended or removed algorithms from that list then prefer algorithms 214 * that are in the list that are supported by known_hosts keys. 215 */ 216 if (options.hostkeyalgorithms == NULL || 217 options.hostkeyalgorithms[0] == '-' || 218 options.hostkeyalgorithms[0] == '+') 219 use_known_hosts_order = 1; 220 221 /* Expand or fill in HostkeyAlgorithms */ 222 all_key = sshkey_alg_list(0, 0, 1, ','); 223 if (kex_assemble_names(&options.hostkeyalgorithms, 224 kex_default_pk_alg(), all_key) != 0) 225 fatal("%s: kex_assemble_namelist", __func__); 226 free(all_key); 227 228 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 229 fatal("%s: kex_names_cat", __func__); 230 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 231 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 232 compat_cipher_proposal(options.ciphers); 233 myproposal[PROPOSAL_ENC_ALGS_STOC] = 234 compat_cipher_proposal(options.ciphers); 235 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 236 myproposal[PROPOSAL_COMP_ALGS_STOC] = 237 (char *)compression_alg_list(options.compression); 238 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 239 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 240 if (use_known_hosts_order) { 241 /* Query known_hosts and prefer algorithms that appear there */ 242 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 243 compat_pkalg_proposal( 244 order_hostkeyalgs(host, hostaddr, port)); 245 } else { 246 /* Use specified HostkeyAlgorithms exactly */ 247 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 248 compat_pkalg_proposal(options.hostkeyalgorithms); 249 } 250 251 if (options.rekey_limit || options.rekey_interval) 252 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 253 options.rekey_interval); 254 255 /* start key exchange */ 256 if ((r = kex_setup(ssh, myproposal)) != 0) 257 fatal("kex_setup: %s", ssh_err(r)); 258 #ifdef WITH_OPENSSL 259 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 260 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 261 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 262 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 263 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 264 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 265 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 266 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 267 #endif 268 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 269 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 270 ssh->kex->verify_host_key=&verify_host_key_callback; 271 272 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 273 274 /* remove ext-info from the KEX proposals for rekeying */ 275 myproposal[PROPOSAL_KEX_ALGS] = 276 compat_kex_proposal(options.kex_algorithms); 277 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 278 fatal("kex_prop2buf: %s", ssh_err(r)); 279 280 session_id2 = ssh->kex->session_id; 281 session_id2_len = ssh->kex->session_id_len; 282 283 #ifdef DEBUG_KEXDH 284 /* send 1st encrypted/maced/compressed message */ 285 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 286 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 287 (r = sshpkt_send(ssh)) != 0 || 288 (r = ssh_packet_write_wait(ssh)) != 0) 289 fatal("%s: %s", __func__, ssh_err(r)); 290 #endif 291 } 292 293 /* 294 * Authenticate user 295 */ 296 297 typedef struct cauthctxt Authctxt; 298 typedef struct cauthmethod Authmethod; 299 typedef struct identity Identity; 300 typedef struct idlist Idlist; 301 302 struct identity { 303 TAILQ_ENTRY(identity) next; 304 int agent_fd; /* >=0 if agent supports key */ 305 struct sshkey *key; /* public/private key */ 306 char *filename; /* comment for agent-only keys */ 307 int tried; 308 int isprivate; /* key points to the private key */ 309 int userprovided; 310 }; 311 TAILQ_HEAD(idlist, identity); 312 313 struct cauthctxt { 314 const char *server_user; 315 const char *local_user; 316 const char *host; 317 const char *service; 318 struct cauthmethod *method; 319 sig_atomic_t success; 320 char *authlist; 321 #ifdef GSSAPI 322 /* gssapi */ 323 gss_OID_set gss_supported_mechs; 324 u_int mech_tried; 325 #endif 326 /* pubkey */ 327 struct idlist keys; 328 int agent_fd; 329 /* hostbased */ 330 Sensitive *sensitive; 331 char *oktypes, *ktypes; 332 const char *active_ktype; 333 /* kbd-interactive */ 334 int info_req_seen; 335 int attempt_kbdint; 336 /* password */ 337 int attempt_passwd; 338 /* generic */ 339 void *methoddata; 340 }; 341 342 struct cauthmethod { 343 char *name; /* string to compare against server's list */ 344 int (*userauth)(struct ssh *ssh); 345 void (*cleanup)(struct ssh *ssh); 346 int *enabled; /* flag in option struct that enables method */ 347 int *batch_flag; /* flag in option struct that disables method */ 348 }; 349 350 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 351 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 352 static int input_userauth_success(int, u_int32_t, struct ssh *); 353 static int input_userauth_failure(int, u_int32_t, struct ssh *); 354 static int input_userauth_banner(int, u_int32_t, struct ssh *); 355 static int input_userauth_error(int, u_int32_t, struct ssh *); 356 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 357 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 358 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 359 360 static int userauth_none(struct ssh *); 361 static int userauth_pubkey(struct ssh *); 362 static int userauth_passwd(struct ssh *); 363 static int userauth_kbdint(struct ssh *); 364 static int userauth_hostbased(struct ssh *); 365 366 #ifdef GSSAPI 367 static int userauth_gssapi(struct ssh *); 368 static void userauth_gssapi_cleanup(struct ssh *); 369 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 370 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 371 static int input_gssapi_error(int, u_int32_t, struct ssh *); 372 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 373 #endif 374 375 void userauth(struct ssh *, char *); 376 377 static void pubkey_cleanup(struct ssh *); 378 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 379 static void pubkey_prepare(Authctxt *); 380 static void pubkey_reset(Authctxt *); 381 static struct sshkey *load_identity_file(Identity *); 382 383 static Authmethod *authmethod_get(char *authlist); 384 static Authmethod *authmethod_lookup(const char *name); 385 static char *authmethods_get(void); 386 387 Authmethod authmethods[] = { 388 #ifdef GSSAPI 389 {"gssapi-with-mic", 390 userauth_gssapi, 391 userauth_gssapi_cleanup, 392 &options.gss_authentication, 393 NULL}, 394 #endif 395 {"hostbased", 396 userauth_hostbased, 397 NULL, 398 &options.hostbased_authentication, 399 NULL}, 400 {"publickey", 401 userauth_pubkey, 402 NULL, 403 &options.pubkey_authentication, 404 NULL}, 405 {"keyboard-interactive", 406 userauth_kbdint, 407 NULL, 408 &options.kbd_interactive_authentication, 409 &options.batch_mode}, 410 {"password", 411 userauth_passwd, 412 NULL, 413 &options.password_authentication, 414 &options.batch_mode}, 415 {"none", 416 userauth_none, 417 NULL, 418 NULL, 419 NULL}, 420 {NULL, NULL, NULL, NULL, NULL} 421 }; 422 423 void 424 ssh_userauth2(struct ssh *ssh, const char *local_user, 425 const char *server_user, char *host, Sensitive *sensitive) 426 { 427 Authctxt authctxt; 428 int r; 429 430 if (options.challenge_response_authentication) 431 options.kbd_interactive_authentication = 1; 432 if (options.preferred_authentications == NULL) 433 options.preferred_authentications = authmethods_get(); 434 435 /* setup authentication context */ 436 memset(&authctxt, 0, sizeof(authctxt)); 437 authctxt.server_user = server_user; 438 authctxt.local_user = local_user; 439 authctxt.host = host; 440 authctxt.service = "ssh-connection"; /* service name */ 441 authctxt.success = 0; 442 authctxt.method = authmethod_lookup("none"); 443 authctxt.authlist = NULL; 444 authctxt.methoddata = NULL; 445 authctxt.sensitive = sensitive; 446 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 447 authctxt.info_req_seen = 0; 448 authctxt.attempt_kbdint = 0; 449 authctxt.attempt_passwd = 0; 450 #if GSSAPI 451 authctxt.gss_supported_mechs = NULL; 452 authctxt.mech_tried = 0; 453 #endif 454 authctxt.agent_fd = -1; 455 pubkey_prepare(&authctxt); 456 if (authctxt.method == NULL) { 457 fatal("%s: internal error: cannot send userauth none request", 458 __func__); 459 } 460 461 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 462 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 463 (r = sshpkt_send(ssh)) != 0) 464 fatal("%s: %s", __func__, ssh_err(r)); 465 466 ssh->authctxt = &authctxt; 467 ssh_dispatch_init(ssh, &input_userauth_error); 468 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 469 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 470 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 471 pubkey_cleanup(ssh); 472 ssh->authctxt = NULL; 473 474 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 475 476 if (!authctxt.success) 477 fatal("Authentication failed."); 478 debug("Authentication succeeded (%s).", authctxt.method->name); 479 } 480 481 /* ARGSUSED */ 482 static int 483 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 484 { 485 int r; 486 487 if (ssh_packet_remaining(ssh) > 0) { 488 char *reply; 489 490 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 491 goto out; 492 debug2("service_accept: %s", reply); 493 free(reply); 494 } else { 495 debug2("buggy server: service_accept w/o service"); 496 } 497 if ((r = sshpkt_get_end(ssh)) != 0) 498 goto out; 499 debug("SSH2_MSG_SERVICE_ACCEPT received"); 500 501 /* initial userauth request */ 502 userauth_none(ssh); 503 504 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 505 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 506 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 507 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 508 r = 0; 509 out: 510 return r; 511 } 512 513 /* ARGSUSED */ 514 static int 515 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 516 { 517 return kex_input_ext_info(type, seqnr, ssh); 518 } 519 520 void 521 userauth(struct ssh *ssh, char *authlist) 522 { 523 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 524 525 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 526 authctxt->method->cleanup(ssh); 527 528 free(authctxt->methoddata); 529 authctxt->methoddata = NULL; 530 if (authlist == NULL) { 531 authlist = authctxt->authlist; 532 } else { 533 free(authctxt->authlist); 534 authctxt->authlist = authlist; 535 } 536 for (;;) { 537 Authmethod *method = authmethod_get(authlist); 538 if (method == NULL) 539 fatal("%s@%s: Permission denied (%s).", 540 authctxt->server_user, authctxt->host, authlist); 541 authctxt->method = method; 542 543 /* reset the per method handler */ 544 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 545 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 546 547 /* and try new method */ 548 if (method->userauth(ssh) != 0) { 549 debug2("we sent a %s packet, wait for reply", method->name); 550 break; 551 } else { 552 debug2("we did not send a packet, disable method"); 553 method->enabled = NULL; 554 } 555 } 556 } 557 558 /* ARGSUSED */ 559 static int 560 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 561 { 562 fatal("%s: bad message during authentication: type %d", __func__, type); 563 return 0; 564 } 565 566 /* ARGSUSED */ 567 static int 568 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 569 { 570 char *msg = NULL; 571 size_t len; 572 int r; 573 574 debug3("%s", __func__); 575 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 576 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 577 goto out; 578 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 579 fmprintf(stderr, "%s", msg); 580 r = 0; 581 out: 582 free(msg); 583 return r; 584 } 585 586 /* ARGSUSED */ 587 static int 588 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 589 { 590 Authctxt *authctxt = ssh->authctxt; 591 592 if (authctxt == NULL) 593 fatal("%s: no authentication context", __func__); 594 free(authctxt->authlist); 595 authctxt->authlist = NULL; 596 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 597 authctxt->method->cleanup(ssh); 598 free(authctxt->methoddata); 599 authctxt->methoddata = NULL; 600 authctxt->success = 1; /* break out */ 601 return 0; 602 } 603 604 #if 0 605 static int 606 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 607 { 608 Authctxt *authctxt = ssh->authctxt; 609 610 if (authctxt == NULL) 611 fatal("%s: no authentication context", __func__); 612 613 fatal("Unexpected authentication success during %s.", 614 authctxt->method->name); 615 return 0; 616 } 617 #endif 618 619 /* ARGSUSED */ 620 static int 621 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 622 { 623 Authctxt *authctxt = ssh->authctxt; 624 char *authlist = NULL; 625 u_char partial; 626 627 if (authctxt == NULL) 628 fatal("input_userauth_failure: no authentication context"); 629 630 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 631 sshpkt_get_u8(ssh, &partial) != 0 || 632 sshpkt_get_end(ssh) != 0) 633 goto out; 634 635 if (partial != 0) { 636 verbose("Authenticated with partial success."); 637 /* reset state */ 638 pubkey_reset(authctxt); 639 } 640 debug("Authentications that can continue: %s", authlist); 641 642 userauth(ssh, authlist); 643 authlist = NULL; 644 out: 645 free(authlist); 646 return 0; 647 } 648 649 /* 650 * Format an identity for logging including filename, key type, fingerprint 651 * and location (agent, etc.). Caller must free. 652 */ 653 static char * 654 format_identity(Identity *id) 655 { 656 char *fp = NULL, *ret = NULL; 657 const char *note = ""; 658 659 if (id->key != NULL) { 660 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 661 SSH_FP_DEFAULT); 662 } 663 if (id->key) { 664 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 665 note = " token"; 666 else if (sshkey_is_sk(id->key)) 667 note = " authenticator"; 668 } 669 xasprintf(&ret, "%s %s%s%s%s%s%s", 670 id->filename, 671 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 672 fp ? fp : "", 673 id->userprovided ? " explicit" : "", note, 674 id->agent_fd != -1 ? " agent" : ""); 675 free(fp); 676 return ret; 677 } 678 679 /* ARGSUSED */ 680 static int 681 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 682 { 683 Authctxt *authctxt = ssh->authctxt; 684 struct sshkey *key = NULL; 685 Identity *id = NULL; 686 int pktype, found = 0, sent = 0; 687 size_t blen; 688 char *pkalg = NULL, *fp = NULL, *ident = NULL; 689 u_char *pkblob = NULL; 690 int r; 691 692 if (authctxt == NULL) 693 fatal("input_userauth_pk_ok: no authentication context"); 694 695 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 696 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 697 (r = sshpkt_get_end(ssh)) != 0) 698 goto done; 699 700 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 701 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 702 goto done; 703 } 704 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 705 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 706 goto done; 707 } 708 if (key->type != pktype) { 709 error("input_userauth_pk_ok: type mismatch " 710 "for decoded key (received %d, expected %d)", 711 key->type, pktype); 712 goto done; 713 } 714 715 /* 716 * search keys in the reverse order, because last candidate has been 717 * moved to the end of the queue. this also avoids confusion by 718 * duplicate keys 719 */ 720 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 721 if (sshkey_equal(key, id->key)) { 722 found = 1; 723 break; 724 } 725 } 726 if (!found || id == NULL) { 727 fp = sshkey_fingerprint(key, options.fingerprint_hash, 728 SSH_FP_DEFAULT); 729 error("%s: server replied with unknown key: %s %s", __func__, 730 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 731 goto done; 732 } 733 ident = format_identity(id); 734 debug("Server accepts key: %s", ident); 735 sent = sign_and_send_pubkey(ssh, id); 736 r = 0; 737 done: 738 sshkey_free(key); 739 free(ident); 740 free(fp); 741 free(pkalg); 742 free(pkblob); 743 744 /* try another method if we did not send a packet */ 745 if (r == 0 && sent == 0) 746 userauth(ssh, NULL); 747 return r; 748 } 749 750 #ifdef GSSAPI 751 static int 752 userauth_gssapi(struct ssh *ssh) 753 { 754 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 755 Gssctxt *gssctxt = NULL; 756 OM_uint32 min; 757 int r, ok = 0; 758 gss_OID mech = NULL; 759 760 /* Try one GSSAPI method at a time, rather than sending them all at 761 * once. */ 762 763 if (authctxt->gss_supported_mechs == NULL) 764 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 765 766 /* Check to see whether the mechanism is usable before we offer it */ 767 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 768 !ok) { 769 mech = &authctxt->gss_supported_mechs-> 770 elements[authctxt->mech_tried]; 771 /* My DER encoding requires length<128 */ 772 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 773 mech, authctxt->host)) { 774 ok = 1; /* Mechanism works */ 775 } else { 776 authctxt->mech_tried++; 777 } 778 } 779 780 if (!ok || mech == NULL) 781 return 0; 782 783 authctxt->methoddata=(void *)gssctxt; 784 785 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 786 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 787 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 788 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 789 (r = sshpkt_put_u32(ssh, 1)) != 0 || 790 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 791 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 792 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 793 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 794 (r = sshpkt_send(ssh)) != 0) 795 fatal("%s: %s", __func__, ssh_err(r)); 796 797 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 798 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 799 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 800 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 801 802 authctxt->mech_tried++; /* Move along to next candidate */ 803 804 return 1; 805 } 806 807 static void 808 userauth_gssapi_cleanup(struct ssh *ssh) 809 { 810 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 811 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 812 813 ssh_gssapi_delete_ctx(&gssctxt); 814 authctxt->methoddata = NULL; 815 816 free(authctxt->gss_supported_mechs); 817 authctxt->gss_supported_mechs = NULL; 818 } 819 820 static OM_uint32 821 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 822 { 823 Authctxt *authctxt = ssh->authctxt; 824 Gssctxt *gssctxt = authctxt->methoddata; 825 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 826 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 827 gss_buffer_desc gssbuf; 828 OM_uint32 status, ms, flags; 829 int r; 830 831 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 832 recv_tok, &send_tok, &flags); 833 834 if (send_tok.length > 0) { 835 u_char type = GSS_ERROR(status) ? 836 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 837 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 838 839 if ((r = sshpkt_start(ssh, type)) != 0 || 840 (r = sshpkt_put_string(ssh, send_tok.value, 841 send_tok.length)) != 0 || 842 (r = sshpkt_send(ssh)) != 0) 843 fatal("%s: %s", __func__, ssh_err(r)); 844 845 gss_release_buffer(&ms, &send_tok); 846 } 847 848 if (status == GSS_S_COMPLETE) { 849 /* send either complete or MIC, depending on mechanism */ 850 if (!(flags & GSS_C_INTEG_FLAG)) { 851 if ((r = sshpkt_start(ssh, 852 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 853 (r = sshpkt_send(ssh)) != 0) 854 fatal("%s: %s", __func__, ssh_err(r)); 855 } else { 856 struct sshbuf *b; 857 858 if ((b = sshbuf_new()) == NULL) 859 fatal("%s: sshbuf_new failed", __func__); 860 ssh_gssapi_buildmic(b, authctxt->server_user, 861 authctxt->service, "gssapi-with-mic"); 862 863 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 864 fatal("%s: sshbuf_mutable_ptr failed", __func__); 865 gssbuf.length = sshbuf_len(b); 866 867 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 868 869 if (!GSS_ERROR(status)) { 870 if ((r = sshpkt_start(ssh, 871 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 872 (r = sshpkt_put_string(ssh, mic.value, 873 mic.length)) != 0 || 874 (r = sshpkt_send(ssh)) != 0) 875 fatal("%s: %s", __func__, ssh_err(r)); 876 } 877 878 sshbuf_free(b); 879 gss_release_buffer(&ms, &mic); 880 } 881 } 882 883 return status; 884 } 885 886 /* ARGSUSED */ 887 static int 888 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 889 { 890 Authctxt *authctxt = ssh->authctxt; 891 Gssctxt *gssctxt; 892 size_t oidlen; 893 u_char *oidv = NULL; 894 int r; 895 896 if (authctxt == NULL) 897 fatal("input_gssapi_response: no authentication context"); 898 gssctxt = authctxt->methoddata; 899 900 /* Setup our OID */ 901 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 902 goto done; 903 904 if (oidlen <= 2 || 905 oidv[0] != SSH_GSS_OIDTYPE || 906 oidv[1] != oidlen - 2) { 907 debug("Badly encoded mechanism OID received"); 908 userauth(ssh, NULL); 909 goto ok; 910 } 911 912 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 913 fatal("Server returned different OID than expected"); 914 915 if ((r = sshpkt_get_end(ssh)) != 0) 916 goto done; 917 918 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 919 /* Start again with next method on list */ 920 debug("Trying to start again"); 921 userauth(ssh, NULL); 922 goto ok; 923 } 924 ok: 925 r = 0; 926 done: 927 free(oidv); 928 return r; 929 } 930 931 /* ARGSUSED */ 932 static int 933 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 934 { 935 Authctxt *authctxt = ssh->authctxt; 936 gss_buffer_desc recv_tok; 937 u_char *p = NULL; 938 size_t len; 939 OM_uint32 status; 940 int r; 941 942 if (authctxt == NULL) 943 fatal("input_gssapi_response: no authentication context"); 944 945 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 946 (r = sshpkt_get_end(ssh)) != 0) 947 goto out; 948 949 recv_tok.value = p; 950 recv_tok.length = len; 951 status = process_gssapi_token(ssh, &recv_tok); 952 953 /* Start again with the next method in the list */ 954 if (GSS_ERROR(status)) { 955 userauth(ssh, NULL); 956 /* ok */ 957 } 958 r = 0; 959 out: 960 free(p); 961 return r; 962 } 963 964 /* ARGSUSED */ 965 static int 966 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 967 { 968 Authctxt *authctxt = ssh->authctxt; 969 Gssctxt *gssctxt; 970 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 971 gss_buffer_desc recv_tok; 972 OM_uint32 ms; 973 u_char *p = NULL; 974 size_t len; 975 int r; 976 977 if (authctxt == NULL) 978 fatal("input_gssapi_response: no authentication context"); 979 gssctxt = authctxt->methoddata; 980 981 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 982 (r = sshpkt_get_end(ssh)) != 0) { 983 free(p); 984 return r; 985 } 986 987 /* Stick it into GSSAPI and see what it says */ 988 recv_tok.value = p; 989 recv_tok.length = len; 990 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 991 &recv_tok, &send_tok, NULL); 992 free(p); 993 gss_release_buffer(&ms, &send_tok); 994 995 /* Server will be returning a failed packet after this one */ 996 return 0; 997 } 998 999 /* ARGSUSED */ 1000 static int 1001 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1002 { 1003 char *msg = NULL; 1004 char *lang = NULL; 1005 int r; 1006 1007 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1008 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1009 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1010 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1011 goto out; 1012 r = sshpkt_get_end(ssh); 1013 debug("Server GSSAPI Error:\n%s", msg); 1014 out: 1015 free(msg); 1016 free(lang); 1017 return r; 1018 } 1019 #endif /* GSSAPI */ 1020 1021 static int 1022 userauth_none(struct ssh *ssh) 1023 { 1024 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1025 int r; 1026 1027 /* initial userauth request */ 1028 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1029 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1030 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1031 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1032 (r = sshpkt_send(ssh)) != 0) 1033 fatal("%s: %s", __func__, ssh_err(r)); 1034 return 1; 1035 } 1036 1037 static int 1038 userauth_passwd(struct ssh *ssh) 1039 { 1040 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1041 char *password, *prompt = NULL; 1042 const char *host = options.host_key_alias ? options.host_key_alias : 1043 authctxt->host; 1044 int r; 1045 1046 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1047 return 0; 1048 1049 if (authctxt->attempt_passwd != 1) 1050 error("Permission denied, please try again."); 1051 1052 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1053 password = read_passphrase(prompt, 0); 1054 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1055 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1056 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1057 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1058 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1059 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1060 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1061 (r = sshpkt_send(ssh)) != 0) 1062 fatal("%s: %s", __func__, ssh_err(r)); 1063 1064 free(prompt); 1065 if (password != NULL) 1066 freezero(password, strlen(password)); 1067 1068 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1069 &input_userauth_passwd_changereq); 1070 1071 return 1; 1072 } 1073 1074 /* 1075 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1076 */ 1077 /* ARGSUSED */ 1078 static int 1079 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1080 { 1081 Authctxt *authctxt = ssh->authctxt; 1082 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1083 char prompt[256]; 1084 const char *host; 1085 int r; 1086 1087 debug2("input_userauth_passwd_changereq"); 1088 1089 if (authctxt == NULL) 1090 fatal("input_userauth_passwd_changereq: " 1091 "no authentication context"); 1092 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1093 1094 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1095 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1096 goto out; 1097 if (strlen(info) > 0) 1098 logit("%s", info); 1099 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1100 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1101 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1102 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1103 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1104 goto out; 1105 1106 snprintf(prompt, sizeof(prompt), 1107 "Enter %.30s@%.128s's old password: ", 1108 authctxt->server_user, host); 1109 password = read_passphrase(prompt, 0); 1110 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1111 goto out; 1112 1113 freezero(password, strlen(password)); 1114 password = NULL; 1115 while (password == NULL) { 1116 snprintf(prompt, sizeof(prompt), 1117 "Enter %.30s@%.128s's new password: ", 1118 authctxt->server_user, host); 1119 password = read_passphrase(prompt, RP_ALLOW_EOF); 1120 if (password == NULL) { 1121 /* bail out */ 1122 r = 0; 1123 goto out; 1124 } 1125 snprintf(prompt, sizeof(prompt), 1126 "Retype %.30s@%.128s's new password: ", 1127 authctxt->server_user, host); 1128 retype = read_passphrase(prompt, 0); 1129 if (strcmp(password, retype) != 0) { 1130 freezero(password, strlen(password)); 1131 logit("Mismatch; try again, EOF to quit."); 1132 password = NULL; 1133 } 1134 freezero(retype, strlen(retype)); 1135 } 1136 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1137 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1138 (r = sshpkt_send(ssh)) != 0) 1139 goto out; 1140 1141 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1142 &input_userauth_passwd_changereq); 1143 r = 0; 1144 out: 1145 if (password) 1146 freezero(password, strlen(password)); 1147 free(info); 1148 free(lang); 1149 return r; 1150 } 1151 1152 /* 1153 * Select an algorithm for publickey signatures. 1154 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1155 * 1156 * Call with ssh==NULL to ignore server-sig-algs extension list and 1157 * only attempt with the key's base signature type. 1158 */ 1159 static char * 1160 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1161 { 1162 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1163 1164 /* 1165 * The signature algorithm will only differ from the key algorithm 1166 * for RSA keys/certs and when the server advertises support for 1167 * newer (SHA2) algorithms. 1168 */ 1169 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1170 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1171 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1172 /* Filter base key signature alg against our configuration */ 1173 return match_list(sshkey_ssh_name(key), 1174 options.pubkey_key_types, NULL); 1175 } 1176 1177 /* 1178 * For RSA keys/certs, since these might have a different sig type: 1179 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1180 * that also appears in the supported signature algorithms list from 1181 * the server. 1182 */ 1183 oallowed = allowed = xstrdup(options.pubkey_key_types); 1184 while ((cp = strsep(&allowed, ",")) != NULL) { 1185 if (sshkey_type_from_name(cp) != key->type) 1186 continue; 1187 tmp = match_list(sshkey_sigalg_by_name(cp), 1188 ssh->kex->server_sig_algs, NULL); 1189 if (tmp != NULL) 1190 alg = xstrdup(cp); 1191 free(tmp); 1192 if (alg != NULL) 1193 break; 1194 } 1195 free(oallowed); 1196 return alg; 1197 } 1198 1199 static int 1200 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1201 const u_char *data, size_t datalen, u_int compat, const char *alg) 1202 { 1203 struct sshkey *sign_key = NULL, *prv = NULL; 1204 int r = SSH_ERR_INTERNAL_ERROR; 1205 struct notifier_ctx *notifier = NULL; 1206 char *fp = NULL, *pin = NULL, *prompt = NULL; 1207 1208 *sigp = NULL; 1209 *lenp = 0; 1210 1211 /* The agent supports this key. */ 1212 if (id->key != NULL && id->agent_fd != -1) { 1213 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1214 data, datalen, alg, compat); 1215 } 1216 1217 /* 1218 * We have already loaded the private key or the private key is 1219 * stored in external hardware. 1220 */ 1221 if (id->key != NULL && 1222 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1223 sign_key = id->key; 1224 } else { 1225 /* Load the private key from the file. */ 1226 if ((prv = load_identity_file(id)) == NULL) 1227 return SSH_ERR_KEY_NOT_FOUND; 1228 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1229 error("%s: private key %s contents do not match public", 1230 __func__, id->filename); 1231 r = SSH_ERR_KEY_NOT_FOUND; 1232 goto out; 1233 } 1234 sign_key = prv; 1235 if (sshkey_is_sk(sign_key)) { 1236 if ((sign_key->sk_flags & 1237 SSH_SK_USER_VERIFICATION_REQD)) { 1238 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1239 sshkey_type(sign_key), id->filename); 1240 pin = read_passphrase(prompt, 0); 1241 } 1242 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1243 /* XXX should batch mode just skip these? */ 1244 if ((fp = sshkey_fingerprint(sign_key, 1245 options.fingerprint_hash, 1246 SSH_FP_DEFAULT)) == NULL) 1247 fatal("%s: fingerprint", __func__); 1248 notifier = notify_start(options.batch_mode, 1249 "Confirm user presence for key %s %s", 1250 sshkey_type(sign_key), fp); 1251 free(fp); 1252 } 1253 } 1254 } 1255 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1256 alg, options.sk_provider, pin, compat)) != 0) { 1257 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1258 goto out; 1259 } 1260 /* 1261 * PKCS#11 tokens may not support all signature algorithms, 1262 * so check what we get back. 1263 */ 1264 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1265 debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r)); 1266 goto out; 1267 } 1268 /* success */ 1269 r = 0; 1270 out: 1271 free(prompt); 1272 if (pin != NULL) 1273 freezero(pin, strlen(pin)); 1274 notify_complete(notifier); 1275 sshkey_free(prv); 1276 return r; 1277 } 1278 1279 static int 1280 id_filename_matches(Identity *id, Identity *private_id) 1281 { 1282 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1283 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1284 size_t i, slen; 1285 1286 if (strcmp(id->filename, private_id->filename) == 0) 1287 return 1; 1288 for (i = 0; suffixes[i]; i++) { 1289 slen = strlen(suffixes[i]); 1290 if (len > slen && plen == len - slen && 1291 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1292 memcmp(id->filename, private_id->filename, plen) == 0) 1293 return 1; 1294 } 1295 return 0; 1296 } 1297 1298 static int 1299 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1300 { 1301 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1302 struct sshbuf *b = NULL; 1303 Identity *private_id, *sign_id = NULL; 1304 u_char *signature = NULL; 1305 size_t slen = 0, skip = 0; 1306 int r, fallback_sigtype, sent = 0; 1307 char *alg = NULL, *fp = NULL; 1308 const char *loc = ""; 1309 1310 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1311 SSH_FP_DEFAULT)) == NULL) 1312 return 0; 1313 1314 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1315 1316 /* 1317 * If the key is an certificate, try to find a matching private key 1318 * and use it to complete the signature. 1319 * If no such private key exists, fall back to trying the certificate 1320 * key itself in case it has a private half already loaded. 1321 * This will try to set sign_id to the private key that will perform 1322 * the signature. 1323 */ 1324 if (sshkey_is_cert(id->key)) { 1325 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1326 if (sshkey_equal_public(id->key, private_id->key) && 1327 id->key->type != private_id->key->type) { 1328 sign_id = private_id; 1329 break; 1330 } 1331 } 1332 /* 1333 * Exact key matches are preferred, but also allow 1334 * filename matches for non-PKCS#11/agent keys that 1335 * didn't load public keys. This supports the case 1336 * of keeping just a private key file and public 1337 * certificate on disk. 1338 */ 1339 if (sign_id == NULL && 1340 !id->isprivate && id->agent_fd == -1 && 1341 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1342 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1343 if (private_id->key == NULL && 1344 id_filename_matches(id, private_id)) { 1345 sign_id = private_id; 1346 break; 1347 } 1348 } 1349 } 1350 if (sign_id != NULL) { 1351 debug2("%s: using private key \"%s\"%s for " 1352 "certificate", __func__, id->filename, 1353 id->agent_fd != -1 ? " from agent" : ""); 1354 } else { 1355 debug("%s: no separate private key for certificate " 1356 "\"%s\"", __func__, id->filename); 1357 } 1358 } 1359 1360 /* 1361 * If the above didn't select another identity to do the signing 1362 * then default to the one we started with. 1363 */ 1364 if (sign_id == NULL) 1365 sign_id = id; 1366 1367 /* assemble and sign data */ 1368 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1369 free(alg); 1370 slen = 0; 1371 signature = NULL; 1372 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1373 id->key)) == NULL) { 1374 error("%s: no mutual signature supported", __func__); 1375 goto out; 1376 } 1377 debug3("%s: signing using %s %s", __func__, alg, fp); 1378 1379 sshbuf_free(b); 1380 if ((b = sshbuf_new()) == NULL) 1381 fatal("%s: sshbuf_new failed", __func__); 1382 if (datafellows & SSH_OLD_SESSIONID) { 1383 if ((r = sshbuf_put(b, session_id2, 1384 session_id2_len)) != 0) { 1385 fatal("%s: sshbuf_put: %s", 1386 __func__, ssh_err(r)); 1387 } 1388 } else { 1389 if ((r = sshbuf_put_string(b, session_id2, 1390 session_id2_len)) != 0) { 1391 fatal("%s: sshbuf_put_string: %s", 1392 __func__, ssh_err(r)); 1393 } 1394 } 1395 skip = sshbuf_len(b); 1396 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1397 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1398 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1399 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1400 (r = sshbuf_put_u8(b, 1)) != 0 || 1401 (r = sshbuf_put_cstring(b, alg)) != 0 || 1402 (r = sshkey_puts(id->key, b)) != 0) { 1403 fatal("%s: assemble signed data: %s", 1404 __func__, ssh_err(r)); 1405 } 1406 1407 /* generate signature */ 1408 r = identity_sign(sign_id, &signature, &slen, 1409 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1410 if (r == 0) 1411 break; 1412 else if (r == SSH_ERR_KEY_NOT_FOUND) 1413 goto out; /* soft failure */ 1414 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1415 !fallback_sigtype) { 1416 if (sign_id->agent_fd != -1) 1417 loc = "agent "; 1418 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1419 loc = "token "; 1420 logit("%skey %s %s returned incorrect signature type", 1421 loc, sshkey_type(id->key), fp); 1422 continue; 1423 } 1424 error("%s: signing failed for %s \"%s\"%s: %s", __func__, 1425 sshkey_type(sign_id->key), sign_id->filename, 1426 id->agent_fd != -1 ? " from agent" : "", ssh_err(r)); 1427 goto out; 1428 } 1429 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1430 fatal("%s: no signature", __func__); 1431 1432 /* append signature */ 1433 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1434 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1435 1436 #ifdef DEBUG_PK 1437 sshbuf_dump(b, stderr); 1438 #endif 1439 /* skip session id and packet type */ 1440 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1441 fatal("%s: consume: %s", __func__, ssh_err(r)); 1442 1443 /* put remaining data from buffer into packet */ 1444 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1445 (r = sshpkt_putb(ssh, b)) != 0 || 1446 (r = sshpkt_send(ssh)) != 0) 1447 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1448 1449 /* success */ 1450 sent = 1; 1451 1452 out: 1453 free(fp); 1454 free(alg); 1455 sshbuf_free(b); 1456 freezero(signature, slen); 1457 return sent; 1458 } 1459 1460 static int 1461 send_pubkey_test(struct ssh *ssh, Identity *id) 1462 { 1463 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1464 u_char *blob = NULL; 1465 char *alg = NULL; 1466 size_t bloblen; 1467 u_int have_sig = 0; 1468 int sent = 0, r; 1469 1470 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1471 debug("%s: no mutual signature algorithm", __func__); 1472 goto out; 1473 } 1474 1475 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1476 /* we cannot handle this key */ 1477 debug3("%s: cannot handle key", __func__); 1478 goto out; 1479 } 1480 /* register callback for USERAUTH_PK_OK message */ 1481 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1482 1483 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1484 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1485 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1486 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1487 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1488 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1489 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1490 (r = sshpkt_send(ssh)) != 0) 1491 fatal("%s: %s", __func__, ssh_err(r)); 1492 sent = 1; 1493 1494 out: 1495 free(alg); 1496 free(blob); 1497 return sent; 1498 } 1499 1500 static struct sshkey * 1501 load_identity_file(Identity *id) 1502 { 1503 struct sshkey *private = NULL; 1504 char prompt[300], *passphrase, *comment; 1505 int r, quit = 0, i; 1506 struct stat st; 1507 1508 if (stat(id->filename, &st) == -1) { 1509 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1510 id->filename, strerror(errno)); 1511 return NULL; 1512 } 1513 snprintf(prompt, sizeof prompt, 1514 "Enter passphrase for key '%.100s': ", id->filename); 1515 for (i = 0; i <= options.number_of_password_prompts; i++) { 1516 if (i == 0) 1517 passphrase = ""; 1518 else { 1519 passphrase = read_passphrase(prompt, 0); 1520 if (*passphrase == '\0') { 1521 debug2("no passphrase given, try next key"); 1522 free(passphrase); 1523 break; 1524 } 1525 } 1526 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1527 passphrase, &private, &comment))) { 1528 case 0: 1529 break; 1530 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1531 if (options.batch_mode) { 1532 quit = 1; 1533 break; 1534 } 1535 if (i != 0) 1536 debug2("bad passphrase given, try again..."); 1537 break; 1538 case SSH_ERR_SYSTEM_ERROR: 1539 if (errno == ENOENT) { 1540 debug2("Load key \"%s\": %s", 1541 id->filename, ssh_err(r)); 1542 quit = 1; 1543 break; 1544 } 1545 /* FALLTHROUGH */ 1546 default: 1547 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1548 quit = 1; 1549 break; 1550 } 1551 if (private != NULL && sshkey_is_sk(private) && 1552 options.sk_provider == NULL) { 1553 debug("key \"%s\" is an authenticator-hosted key, " 1554 "but no provider specified", id->filename); 1555 sshkey_free(private); 1556 private = NULL; 1557 quit = 1; 1558 } 1559 if (!quit && private != NULL && id->agent_fd == -1 && 1560 !(id->key && id->isprivate)) 1561 maybe_add_key_to_agent(id->filename, private, comment, 1562 passphrase); 1563 if (i > 0) 1564 freezero(passphrase, strlen(passphrase)); 1565 free(comment); 1566 if (private != NULL || quit) 1567 break; 1568 } 1569 return private; 1570 } 1571 1572 static int 1573 key_type_allowed_by_config(struct sshkey *key) 1574 { 1575 if (match_pattern_list(sshkey_ssh_name(key), 1576 options.pubkey_key_types, 0) == 1) 1577 return 1; 1578 1579 /* RSA keys/certs might be allowed by alternate signature types */ 1580 switch (key->type) { 1581 case KEY_RSA: 1582 if (match_pattern_list("rsa-sha2-512", 1583 options.pubkey_key_types, 0) == 1) 1584 return 1; 1585 if (match_pattern_list("rsa-sha2-256", 1586 options.pubkey_key_types, 0) == 1) 1587 return 1; 1588 break; 1589 case KEY_RSA_CERT: 1590 if (match_pattern_list("rsa-sha2-512-cert-v01 (at) openssh.com", 1591 options.pubkey_key_types, 0) == 1) 1592 return 1; 1593 if (match_pattern_list("rsa-sha2-256-cert-v01 (at) openssh.com", 1594 options.pubkey_key_types, 0) == 1) 1595 return 1; 1596 break; 1597 } 1598 return 0; 1599 } 1600 1601 1602 /* 1603 * try keys in the following order: 1604 * 1. certificates listed in the config file 1605 * 2. other input certificates 1606 * 3. agent keys that are found in the config file 1607 * 4. other agent keys 1608 * 5. keys that are only listed in the config file 1609 */ 1610 static void 1611 pubkey_prepare(Authctxt *authctxt) 1612 { 1613 struct identity *id, *id2, *tmp; 1614 struct idlist agent, files, *preferred; 1615 struct sshkey *key; 1616 int agent_fd = -1, i, r, found; 1617 size_t j; 1618 struct ssh_identitylist *idlist; 1619 char *ident; 1620 1621 TAILQ_INIT(&agent); /* keys from the agent */ 1622 TAILQ_INIT(&files); /* keys from the config file */ 1623 preferred = &authctxt->keys; 1624 TAILQ_INIT(preferred); /* preferred order of keys */ 1625 1626 /* list of keys stored in the filesystem and PKCS#11 */ 1627 for (i = 0; i < options.num_identity_files; i++) { 1628 key = options.identity_keys[i]; 1629 if (key && key->cert && 1630 key->cert->type != SSH2_CERT_TYPE_USER) { 1631 debug("%s: ignoring certificate %s: not a user " 1632 "certificate", __func__, 1633 options.identity_files[i]); 1634 continue; 1635 } 1636 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1637 debug("%s: ignoring authenticator-hosted key %s as no " 1638 "SecurityKeyProvider has been specified", 1639 __func__, options.identity_files[i]); 1640 continue; 1641 } 1642 options.identity_keys[i] = NULL; 1643 id = xcalloc(1, sizeof(*id)); 1644 id->agent_fd = -1; 1645 id->key = key; 1646 id->filename = xstrdup(options.identity_files[i]); 1647 id->userprovided = options.identity_file_userprovided[i]; 1648 TAILQ_INSERT_TAIL(&files, id, next); 1649 } 1650 /* list of certificates specified by user */ 1651 for (i = 0; i < options.num_certificate_files; i++) { 1652 key = options.certificates[i]; 1653 if (!sshkey_is_cert(key) || key->cert == NULL || 1654 key->cert->type != SSH2_CERT_TYPE_USER) { 1655 debug("%s: ignoring certificate %s: not a user " 1656 "certificate", __func__, 1657 options.identity_files[i]); 1658 continue; 1659 } 1660 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1661 debug("%s: ignoring authenticator-hosted key " 1662 "certificate %s as no " 1663 "SecurityKeyProvider has been specified", 1664 __func__, options.identity_files[i]); 1665 continue; 1666 } 1667 id = xcalloc(1, sizeof(*id)); 1668 id->agent_fd = -1; 1669 id->key = key; 1670 id->filename = xstrdup(options.certificate_files[i]); 1671 id->userprovided = options.certificate_file_userprovided[i]; 1672 TAILQ_INSERT_TAIL(preferred, id, next); 1673 } 1674 /* list of keys supported by the agent */ 1675 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1676 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1677 debug("%s: ssh_get_authentication_socket: %s", 1678 __func__, ssh_err(r)); 1679 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1680 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1681 debug("%s: ssh_fetch_identitylist: %s", 1682 __func__, ssh_err(r)); 1683 close(agent_fd); 1684 } else { 1685 for (j = 0; j < idlist->nkeys; j++) { 1686 found = 0; 1687 TAILQ_FOREACH(id, &files, next) { 1688 /* 1689 * agent keys from the config file are 1690 * preferred 1691 */ 1692 if (sshkey_equal(idlist->keys[j], id->key)) { 1693 TAILQ_REMOVE(&files, id, next); 1694 TAILQ_INSERT_TAIL(preferred, id, next); 1695 id->agent_fd = agent_fd; 1696 found = 1; 1697 break; 1698 } 1699 } 1700 if (!found && !options.identities_only) { 1701 id = xcalloc(1, sizeof(*id)); 1702 /* XXX "steals" key/comment from idlist */ 1703 id->key = idlist->keys[j]; 1704 id->filename = idlist->comments[j]; 1705 idlist->keys[j] = NULL; 1706 idlist->comments[j] = NULL; 1707 id->agent_fd = agent_fd; 1708 TAILQ_INSERT_TAIL(&agent, id, next); 1709 } 1710 } 1711 ssh_free_identitylist(idlist); 1712 /* append remaining agent keys */ 1713 TAILQ_CONCAT(preferred, &agent, next); 1714 authctxt->agent_fd = agent_fd; 1715 } 1716 /* Prefer PKCS11 keys that are explicitly listed */ 1717 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1718 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1719 continue; 1720 found = 0; 1721 TAILQ_FOREACH(id2, &files, next) { 1722 if (id2->key == NULL || 1723 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1724 continue; 1725 if (sshkey_equal(id->key, id2->key)) { 1726 TAILQ_REMOVE(&files, id, next); 1727 TAILQ_INSERT_TAIL(preferred, id, next); 1728 found = 1; 1729 break; 1730 } 1731 } 1732 /* If IdentitiesOnly set and key not found then don't use it */ 1733 if (!found && options.identities_only) { 1734 TAILQ_REMOVE(&files, id, next); 1735 freezero(id, sizeof(*id)); 1736 } 1737 } 1738 /* append remaining keys from the config file */ 1739 TAILQ_CONCAT(preferred, &files, next); 1740 /* finally, filter by PubkeyAcceptedKeyTypes */ 1741 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1742 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1743 debug("Skipping %s key %s - " 1744 "not in PubkeyAcceptedKeyTypes", 1745 sshkey_ssh_name(id->key), id->filename); 1746 TAILQ_REMOVE(preferred, id, next); 1747 sshkey_free(id->key); 1748 free(id->filename); 1749 memset(id, 0, sizeof(*id)); 1750 continue; 1751 } 1752 } 1753 /* List the keys we plan on using */ 1754 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1755 ident = format_identity(id); 1756 debug("Will attempt key: %s", ident); 1757 free(ident); 1758 } 1759 debug2("%s: done", __func__); 1760 } 1761 1762 static void 1763 pubkey_cleanup(struct ssh *ssh) 1764 { 1765 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1766 Identity *id; 1767 1768 if (authctxt->agent_fd != -1) { 1769 ssh_close_authentication_socket(authctxt->agent_fd); 1770 authctxt->agent_fd = -1; 1771 } 1772 for (id = TAILQ_FIRST(&authctxt->keys); id; 1773 id = TAILQ_FIRST(&authctxt->keys)) { 1774 TAILQ_REMOVE(&authctxt->keys, id, next); 1775 sshkey_free(id->key); 1776 free(id->filename); 1777 free(id); 1778 } 1779 } 1780 1781 static void 1782 pubkey_reset(Authctxt *authctxt) 1783 { 1784 Identity *id; 1785 1786 TAILQ_FOREACH(id, &authctxt->keys, next) 1787 id->tried = 0; 1788 } 1789 1790 static int 1791 try_identity(Identity *id) 1792 { 1793 if (!id->key) 1794 return (0); 1795 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1796 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1797 debug("Skipped %s key %s for RSA/MD5 server", 1798 sshkey_type(id->key), id->filename); 1799 return (0); 1800 } 1801 return 1; 1802 } 1803 1804 static int 1805 userauth_pubkey(struct ssh *ssh) 1806 { 1807 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1808 Identity *id; 1809 int sent = 0; 1810 char *ident; 1811 1812 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1813 if (id->tried++) 1814 return (0); 1815 /* move key to the end of the queue */ 1816 TAILQ_REMOVE(&authctxt->keys, id, next); 1817 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1818 /* 1819 * send a test message if we have the public key. for 1820 * encrypted keys we cannot do this and have to load the 1821 * private key instead 1822 */ 1823 if (id->key != NULL) { 1824 if (try_identity(id)) { 1825 ident = format_identity(id); 1826 debug("Offering public key: %s", ident); 1827 free(ident); 1828 sent = send_pubkey_test(ssh, id); 1829 } 1830 } else { 1831 debug("Trying private key: %s", id->filename); 1832 id->key = load_identity_file(id); 1833 if (id->key != NULL) { 1834 if (try_identity(id)) { 1835 id->isprivate = 1; 1836 sent = sign_and_send_pubkey(ssh, id); 1837 } 1838 sshkey_free(id->key); 1839 id->key = NULL; 1840 id->isprivate = 0; 1841 } 1842 } 1843 if (sent) 1844 return (sent); 1845 } 1846 return (0); 1847 } 1848 1849 /* 1850 * Send userauth request message specifying keyboard-interactive method. 1851 */ 1852 static int 1853 userauth_kbdint(struct ssh *ssh) 1854 { 1855 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1856 int r; 1857 1858 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1859 return 0; 1860 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1861 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1862 debug3("userauth_kbdint: disable: no info_req_seen"); 1863 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1864 return 0; 1865 } 1866 1867 debug2("userauth_kbdint"); 1868 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1869 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1870 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1871 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1872 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1873 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1874 options.kbd_interactive_devices : "")) != 0 || 1875 (r = sshpkt_send(ssh)) != 0) 1876 fatal("%s: %s", __func__, ssh_err(r)); 1877 1878 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1879 return 1; 1880 } 1881 1882 /* 1883 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1884 */ 1885 static int 1886 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1887 { 1888 Authctxt *authctxt = ssh->authctxt; 1889 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1890 char *response = NULL; 1891 u_char echo = 0; 1892 u_int num_prompts, i; 1893 int r; 1894 1895 debug2("input_userauth_info_req"); 1896 1897 if (authctxt == NULL) 1898 fatal("input_userauth_info_req: no authentication context"); 1899 1900 authctxt->info_req_seen = 1; 1901 1902 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1903 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1904 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1905 goto out; 1906 if (strlen(name) > 0) 1907 logit("%s", name); 1908 if (strlen(inst) > 0) 1909 logit("%s", inst); 1910 1911 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1912 goto out; 1913 /* 1914 * Begin to build info response packet based on prompts requested. 1915 * We commit to providing the correct number of responses, so if 1916 * further on we run into a problem that prevents this, we have to 1917 * be sure and clean this up and send a correct error response. 1918 */ 1919 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1920 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1921 goto out; 1922 1923 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1924 for (i = 0; i < num_prompts; i++) { 1925 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1926 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1927 goto out; 1928 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1929 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1930 goto out; 1931 freezero(response, strlen(response)); 1932 free(prompt); 1933 response = prompt = NULL; 1934 } 1935 /* done with parsing incoming message. */ 1936 if ((r = sshpkt_get_end(ssh)) != 0 || 1937 (r = sshpkt_add_padding(ssh, 64)) != 0) 1938 goto out; 1939 r = sshpkt_send(ssh); 1940 out: 1941 if (response) 1942 freezero(response, strlen(response)); 1943 free(prompt); 1944 free(name); 1945 free(inst); 1946 free(lang); 1947 return r; 1948 } 1949 1950 static int 1951 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1952 const u_char *data, size_t datalen) 1953 { 1954 struct sshbuf *b; 1955 struct stat st; 1956 pid_t pid; 1957 int r, to[2], from[2], status; 1958 int sock = ssh_packet_get_connection_in(ssh); 1959 u_char rversion = 0, version = 2; 1960 void (*osigchld)(int); 1961 1962 *sigp = NULL; 1963 *lenp = 0; 1964 1965 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1966 error("%s: not installed: %s", __func__, strerror(errno)); 1967 return -1; 1968 } 1969 if (fflush(stdout) != 0) { 1970 error("%s: fflush: %s", __func__, strerror(errno)); 1971 return -1; 1972 } 1973 if (pipe(to) == -1) { 1974 error("%s: pipe: %s", __func__, strerror(errno)); 1975 return -1; 1976 } 1977 if (pipe(from) == -1) { 1978 error("%s: pipe: %s", __func__, strerror(errno)); 1979 return -1; 1980 } 1981 if ((pid = fork()) == -1) { 1982 error("%s: fork: %s", __func__, strerror(errno)); 1983 return -1; 1984 } 1985 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1986 if (pid == 0) { 1987 close(from[0]); 1988 if (dup2(from[1], STDOUT_FILENO) == -1) 1989 fatal("%s: dup2: %s", __func__, strerror(errno)); 1990 close(to[1]); 1991 if (dup2(to[0], STDIN_FILENO) == -1) 1992 fatal("%s: dup2: %s", __func__, strerror(errno)); 1993 close(from[1]); 1994 close(to[0]); 1995 1996 if (dup2(sock, STDERR_FILENO + 1) == -1) 1997 fatal("%s: dup2: %s", __func__, strerror(errno)); 1998 sock = STDERR_FILENO + 1; 1999 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2000 closefrom(sock + 1); 2001 2002 debug3("%s: [child] pid=%ld, exec %s", 2003 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 2004 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2005 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 2006 strerror(errno)); 2007 } 2008 close(from[1]); 2009 close(to[0]); 2010 sock = STDERR_FILENO + 1; 2011 2012 if ((b = sshbuf_new()) == NULL) 2013 fatal("%s: sshbuf_new failed", __func__); 2014 /* send # of sock, data to be signed */ 2015 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2016 (r = sshbuf_put_string(b, data, datalen)) != 0) 2017 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 2018 if (ssh_msg_send(to[1], version, b) == -1) 2019 fatal("%s: couldn't send request", __func__); 2020 sshbuf_reset(b); 2021 r = ssh_msg_recv(from[0], b); 2022 close(from[0]); 2023 close(to[1]); 2024 if (r < 0) { 2025 error("%s: no reply", __func__); 2026 goto fail; 2027 } 2028 2029 errno = 0; 2030 while (waitpid(pid, &status, 0) == -1) { 2031 if (errno != EINTR) { 2032 error("%s: waitpid %ld: %s", 2033 __func__, (long)pid, strerror(errno)); 2034 goto fail; 2035 } 2036 } 2037 if (!WIFEXITED(status)) { 2038 error("%s: exited abnormally", __func__); 2039 goto fail; 2040 } 2041 if (WEXITSTATUS(status) != 0) { 2042 error("%s: exited with status %d", 2043 __func__, WEXITSTATUS(status)); 2044 goto fail; 2045 } 2046 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2047 error("%s: buffer error: %s", __func__, ssh_err(r)); 2048 goto fail; 2049 } 2050 if (rversion != version) { 2051 error("%s: bad version", __func__); 2052 goto fail; 2053 } 2054 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2055 error("%s: buffer error: %s", __func__, ssh_err(r)); 2056 fail: 2057 ssh_signal(SIGCHLD, osigchld); 2058 sshbuf_free(b); 2059 return -1; 2060 } 2061 ssh_signal(SIGCHLD, osigchld); 2062 sshbuf_free(b); 2063 2064 return 0; 2065 } 2066 2067 static int 2068 userauth_hostbased(struct ssh *ssh) 2069 { 2070 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2071 struct sshkey *private = NULL; 2072 struct sshbuf *b = NULL; 2073 u_char *sig = NULL, *keyblob = NULL; 2074 char *fp = NULL, *chost = NULL, *lname = NULL; 2075 size_t siglen = 0, keylen = 0; 2076 int i, r, success = 0; 2077 2078 if (authctxt->ktypes == NULL) { 2079 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2080 authctxt->ktypes = authctxt->oktypes; 2081 } 2082 2083 /* 2084 * Work through each listed type pattern in HostbasedKeyTypes, 2085 * trying each hostkey that matches the type in turn. 2086 */ 2087 for (;;) { 2088 if (authctxt->active_ktype == NULL) 2089 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2090 if (authctxt->active_ktype == NULL || 2091 *authctxt->active_ktype == '\0') 2092 break; 2093 debug3("%s: trying key type %s", __func__, 2094 authctxt->active_ktype); 2095 2096 /* check for a useful key */ 2097 private = NULL; 2098 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2099 if (authctxt->sensitive->keys[i] == NULL || 2100 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2101 continue; 2102 if (match_pattern_list( 2103 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2104 authctxt->active_ktype, 0) != 1) 2105 continue; 2106 /* we take and free the key */ 2107 private = authctxt->sensitive->keys[i]; 2108 authctxt->sensitive->keys[i] = NULL; 2109 break; 2110 } 2111 /* Found one */ 2112 if (private != NULL) 2113 break; 2114 /* No more keys of this type; advance */ 2115 authctxt->active_ktype = NULL; 2116 } 2117 if (private == NULL) { 2118 free(authctxt->oktypes); 2119 authctxt->oktypes = authctxt->ktypes = NULL; 2120 authctxt->active_ktype = NULL; 2121 debug("No more client hostkeys for hostbased authentication."); 2122 goto out; 2123 } 2124 2125 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2126 SSH_FP_DEFAULT)) == NULL) { 2127 error("%s: sshkey_fingerprint failed", __func__); 2128 goto out; 2129 } 2130 debug("%s: trying hostkey %s %s", 2131 __func__, sshkey_ssh_name(private), fp); 2132 2133 /* figure out a name for the client host */ 2134 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2135 if (lname == NULL) { 2136 error("%s: cannot get local ipaddr/name", __func__); 2137 goto out; 2138 } 2139 2140 /* XXX sshbuf_put_stringf? */ 2141 xasprintf(&chost, "%s.", lname); 2142 debug2("%s: chost %s", __func__, chost); 2143 2144 /* construct data */ 2145 if ((b = sshbuf_new()) == NULL) { 2146 error("%s: sshbuf_new failed", __func__); 2147 goto out; 2148 } 2149 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2150 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2151 goto out; 2152 } 2153 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2154 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2155 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2156 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2157 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2158 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2159 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2160 (r = sshbuf_put_cstring(b, chost)) != 0 || 2161 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2162 error("%s: buffer error: %s", __func__, ssh_err(r)); 2163 goto out; 2164 } 2165 2166 #ifdef DEBUG_PK 2167 sshbuf_dump(b, stderr); 2168 #endif 2169 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2170 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2171 error("sign using hostkey %s %s failed", 2172 sshkey_ssh_name(private), fp); 2173 goto out; 2174 } 2175 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2176 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2177 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2178 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2179 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2180 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2181 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2182 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2183 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2184 (r = sshpkt_send(ssh)) != 0) { 2185 error("%s: packet error: %s", __func__, ssh_err(r)); 2186 goto out; 2187 } 2188 success = 1; 2189 2190 out: 2191 if (sig != NULL) 2192 freezero(sig, siglen); 2193 free(keyblob); 2194 free(lname); 2195 free(fp); 2196 free(chost); 2197 sshkey_free(private); 2198 sshbuf_free(b); 2199 2200 return success; 2201 } 2202 2203 /* find auth method */ 2204 2205 /* 2206 * given auth method name, if configurable options permit this method fill 2207 * in auth_ident field and return true, otherwise return false. 2208 */ 2209 static int 2210 authmethod_is_enabled(Authmethod *method) 2211 { 2212 if (method == NULL) 2213 return 0; 2214 /* return false if options indicate this method is disabled */ 2215 if (method->enabled == NULL || *method->enabled == 0) 2216 return 0; 2217 /* return false if batch mode is enabled but method needs interactive mode */ 2218 if (method->batch_flag != NULL && *method->batch_flag != 0) 2219 return 0; 2220 return 1; 2221 } 2222 2223 static Authmethod * 2224 authmethod_lookup(const char *name) 2225 { 2226 Authmethod *method = NULL; 2227 if (name != NULL) 2228 for (method = authmethods; method->name != NULL; method++) 2229 if (strcmp(name, method->name) == 0) 2230 return method; 2231 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2232 return NULL; 2233 } 2234 2235 /* XXX internal state */ 2236 static Authmethod *current = NULL; 2237 static char *supported = NULL; 2238 static char *preferred = NULL; 2239 2240 /* 2241 * Given the authentication method list sent by the server, return the 2242 * next method we should try. If the server initially sends a nil list, 2243 * use a built-in default list. 2244 */ 2245 static Authmethod * 2246 authmethod_get(char *authlist) 2247 { 2248 char *name = NULL; 2249 u_int next; 2250 2251 /* Use a suitable default if we're passed a nil list. */ 2252 if (authlist == NULL || strlen(authlist) == 0) 2253 authlist = options.preferred_authentications; 2254 2255 if (supported == NULL || strcmp(authlist, supported) != 0) { 2256 debug3("start over, passed a different list %s", authlist); 2257 free(supported); 2258 supported = xstrdup(authlist); 2259 preferred = options.preferred_authentications; 2260 debug3("preferred %s", preferred); 2261 current = NULL; 2262 } else if (current != NULL && authmethod_is_enabled(current)) 2263 return current; 2264 2265 for (;;) { 2266 if ((name = match_list(preferred, supported, &next)) == NULL) { 2267 debug("No more authentication methods to try."); 2268 current = NULL; 2269 return NULL; 2270 } 2271 preferred += next; 2272 debug3("authmethod_lookup %s", name); 2273 debug3("remaining preferred: %s", preferred); 2274 if ((current = authmethod_lookup(name)) != NULL && 2275 authmethod_is_enabled(current)) { 2276 debug3("authmethod_is_enabled %s", name); 2277 debug("Next authentication method: %s", name); 2278 free(name); 2279 return current; 2280 } 2281 free(name); 2282 } 2283 } 2284 2285 static char * 2286 authmethods_get(void) 2287 { 2288 Authmethod *method = NULL; 2289 struct sshbuf *b; 2290 char *list; 2291 int r; 2292 2293 if ((b = sshbuf_new()) == NULL) 2294 fatal("%s: sshbuf_new failed", __func__); 2295 for (method = authmethods; method->name != NULL; method++) { 2296 if (authmethod_is_enabled(method)) { 2297 if ((r = sshbuf_putf(b, "%s%s", 2298 sshbuf_len(b) ? "," : "", method->name)) != 0) 2299 fatal("%s: buffer error: %s", 2300 __func__, ssh_err(r)); 2301 } 2302 } 2303 if ((list = sshbuf_dup_string(b)) == NULL) 2304 fatal("%s: sshbuf_dup_string failed", __func__); 2305 sshbuf_free(b); 2306 return list; 2307 } 2308
Indexes created Fri Mar 06 19:51:54 UTC 2026