1 /* $OpenBSD: sshconnect2.c,v 1.340 2020/12/29 00:59:15 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 <limits.h> 36 #include <netdb.h> 37 #include <stdio.h> 38 #include <string.h> 39 #include <stdarg.h> 40 #include <signal.h> 41 #include <pwd.h> 42 #include <unistd.h> 43 #include <vis.h> 44 45 #include "xmalloc.h" 46 #include "ssh.h" 47 #include "ssh2.h" 48 #include "sshbuf.h" 49 #include "packet.h" 50 #include "compat.h" 51 #include "cipher.h" 52 #include "sshkey.h" 53 #include "kex.h" 54 #include "myproposal.h" 55 #include "sshconnect.h" 56 #include "authfile.h" 57 #include "dh.h" 58 #include "authfd.h" 59 #include "log.h" 60 #include "misc.h" 61 #include "readconf.h" 62 #include "match.h" 63 #include "dispatch.h" 64 #include "canohost.h" 65 #include "msg.h" 66 #include "pathnames.h" 67 #include "uidswap.h" 68 #include "hostfile.h" 69 #include "ssherr.h" 70 #include "utf8.h" 71 #include "ssh-sk.h" 72 #include "sk-api.h" 73 74 #ifdef GSSAPI 75 #include "ssh-gss.h" 76 #endif 77 78 /* import */ 79 extern char *client_version_string; 80 extern char *server_version_string; 81 extern Options options; 82 83 /* 84 * SSH2 key exchange 85 */ 86 87 u_char *session_id2 = NULL; 88 u_int session_id2_len = 0; 89 90 static char *xxx_host; 91 static struct sockaddr *xxx_hostaddr; 92 static const struct ssh_conn_info *xxx_conn_info; 93 94 static int 95 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 96 { 97 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 98 xxx_conn_info) == -1) 99 fatal("Host key verification failed."); 100 return 0; 101 } 102 103 /* Returns the first item from a comma-separated algorithm list */ 104 static char * 105 first_alg(const char *algs) 106 { 107 char *ret, *cp; 108 109 ret = xstrdup(algs); 110 if ((cp = strchr(ret, ',')) != NULL) 111 *cp = '\0'; 112 return ret; 113 } 114 115 static char * 116 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 117 const struct ssh_conn_info *cinfo) 118 { 119 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 120 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 121 size_t maxlen; 122 struct hostkeys *hostkeys = NULL; 123 int ktype; 124 u_int i; 125 126 /* Find all hostkeys for this hostname */ 127 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 128 hostkeys = init_hostkeys(); 129 for (i = 0; i < options.num_user_hostfiles; i++) 130 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 131 for (i = 0; i < options.num_system_hostfiles; i++) { 132 load_hostkeys(hostkeys, hostname, 133 options.system_hostfiles[i], 0); 134 } 135 if (options.known_hosts_command != NULL) { 136 load_hostkeys_command(hostkeys, options.known_hosts_command, 137 "ORDER", cinfo, NULL, host); 138 } 139 /* 140 * If a plain public key exists that matches the type of the best 141 * preference HostkeyAlgorithms, then use the whole list as is. 142 * Note that we ignore whether the best preference algorithm is a 143 * certificate type, as sshconnect.c will downgrade certs to 144 * plain keys if necessary. 145 */ 146 best = first_alg(options.hostkeyalgorithms); 147 if (lookup_key_in_hostkeys_by_type(hostkeys, 148 sshkey_type_plain(sshkey_type_from_name(best)), 149 sshkey_ecdsa_nid_from_name(best), NULL)) { 150 debug3_f("have matching best-preference key type %s, " 151 "using HostkeyAlgorithms verbatim", best); 152 ret = xstrdup(options.hostkeyalgorithms); 153 goto out; 154 } 155 156 /* 157 * Otherwise, prefer the host key algorithms that match known keys 158 * while keeping the ordering of HostkeyAlgorithms as much as possible. 159 */ 160 oavail = avail = xstrdup(options.hostkeyalgorithms); 161 maxlen = strlen(avail) + 1; 162 first = xmalloc(maxlen); 163 last = xmalloc(maxlen); 164 *first = *last = '\0'; 165 166 #define ALG_APPEND(to, from) \ 167 do { \ 168 if (*to != '\0') \ 169 strlcat(to, ",", maxlen); \ 170 strlcat(to, from, maxlen); \ 171 } while (0) 172 173 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 174 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 175 fatal_f("unknown alg %s", alg); 176 /* 177 * If we have a @cert-authority marker in known_hosts then 178 * prefer all certificate algorithms. 179 */ 180 if (sshkey_type_is_cert(ktype) && 181 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 182 ALG_APPEND(first, alg); 183 continue; 184 } 185 /* If the key appears in known_hosts then prefer it */ 186 if (lookup_key_in_hostkeys_by_type(hostkeys, 187 sshkey_type_plain(ktype), 188 sshkey_ecdsa_nid_from_name(alg), NULL)) { 189 ALG_APPEND(first, alg); 190 continue; 191 } 192 /* Otherwise, put it last */ 193 ALG_APPEND(last, alg); 194 } 195 #undef ALG_APPEND 196 xasprintf(&ret, "%s%s%s", first, 197 (*first == '\0' || *last == '\0') ? "" : ",", last); 198 if (*first != '\0') 199 debug3_f("prefer hostkeyalgs: %s", first); 200 else 201 debug3_f("no algorithms matched; accept original"); 202 out: 203 free(best); 204 free(first); 205 free(last); 206 free(hostname); 207 free(oavail); 208 free_hostkeys(hostkeys); 209 210 return ret; 211 } 212 213 void 214 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 215 const struct ssh_conn_info *cinfo) 216 { 217 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 218 char *s, *all_key; 219 int r, use_known_hosts_order = 0; 220 221 xxx_host = host; 222 xxx_hostaddr = hostaddr; 223 xxx_conn_info = cinfo; 224 225 /* 226 * If the user has not specified HostkeyAlgorithms, or has only 227 * appended or removed algorithms from that list then prefer algorithms 228 * that are in the list that are supported by known_hosts keys. 229 */ 230 if (options.hostkeyalgorithms == NULL || 231 options.hostkeyalgorithms[0] == '-' || 232 options.hostkeyalgorithms[0] == '+') 233 use_known_hosts_order = 1; 234 235 /* Expand or fill in HostkeyAlgorithms */ 236 all_key = sshkey_alg_list(0, 0, 1, ','); 237 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 238 kex_default_pk_alg(), all_key)) != 0) 239 fatal_fr(r, "kex_assemble_namelist"); 240 free(all_key); 241 242 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 243 fatal_f("kex_names_cat"); 244 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 245 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 246 compat_cipher_proposal(options.ciphers); 247 myproposal[PROPOSAL_ENC_ALGS_STOC] = 248 compat_cipher_proposal(options.ciphers); 249 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 250 myproposal[PROPOSAL_COMP_ALGS_STOC] = 251 (char *)compression_alg_list(options.compression); 252 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 253 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 254 if (use_known_hosts_order) { 255 /* Query known_hosts and prefer algorithms that appear there */ 256 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 257 compat_pkalg_proposal( 258 order_hostkeyalgs(host, hostaddr, port, cinfo)); 259 } else { 260 /* Use specified HostkeyAlgorithms exactly */ 261 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 262 compat_pkalg_proposal(options.hostkeyalgorithms); 263 } 264 265 if (options.rekey_limit || options.rekey_interval) 266 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 267 options.rekey_interval); 268 269 /* start key exchange */ 270 if ((r = kex_setup(ssh, myproposal)) != 0) 271 fatal_r(r, "kex_setup"); 272 #ifdef WITH_OPENSSL 273 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 274 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 275 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 276 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 277 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 278 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 279 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 280 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 281 #endif 282 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 283 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 284 ssh->kex->verify_host_key=&verify_host_key_callback; 285 286 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 287 288 /* remove ext-info from the KEX proposals for rekeying */ 289 myproposal[PROPOSAL_KEX_ALGS] = 290 compat_kex_proposal(options.kex_algorithms); 291 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 292 fatal_r(r, "kex_prop2buf"); 293 294 session_id2 = ssh->kex->session_id; 295 session_id2_len = ssh->kex->session_id_len; 296 297 #ifdef DEBUG_KEXDH 298 /* send 1st encrypted/maced/compressed message */ 299 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 300 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 301 (r = sshpkt_send(ssh)) != 0 || 302 (r = ssh_packet_write_wait(ssh)) != 0) 303 fatal_fr(r, "send packet"); 304 #endif 305 } 306 307 /* 308 * Authenticate user 309 */ 310 311 typedef struct cauthctxt Authctxt; 312 typedef struct cauthmethod Authmethod; 313 typedef struct identity Identity; 314 typedef struct idlist Idlist; 315 316 struct identity { 317 TAILQ_ENTRY(identity) next; 318 int agent_fd; /* >=0 if agent supports key */ 319 struct sshkey *key; /* public/private key */ 320 char *filename; /* comment for agent-only keys */ 321 int tried; 322 int isprivate; /* key points to the private key */ 323 int userprovided; 324 }; 325 TAILQ_HEAD(idlist, identity); 326 327 struct cauthctxt { 328 const char *server_user; 329 const char *local_user; 330 const char *host; 331 const char *service; 332 struct cauthmethod *method; 333 sig_atomic_t success; 334 char *authlist; 335 #ifdef GSSAPI 336 /* gssapi */ 337 gss_OID_set gss_supported_mechs; 338 u_int mech_tried; 339 #endif 340 /* pubkey */ 341 struct idlist keys; 342 int agent_fd; 343 /* hostbased */ 344 Sensitive *sensitive; 345 char *oktypes, *ktypes; 346 const char *active_ktype; 347 /* kbd-interactive */ 348 int info_req_seen; 349 int attempt_kbdint; 350 /* password */ 351 int attempt_passwd; 352 /* generic */ 353 void *methoddata; 354 }; 355 356 struct cauthmethod { 357 char *name; /* string to compare against server's list */ 358 int (*userauth)(struct ssh *ssh); 359 void (*cleanup)(struct ssh *ssh); 360 int *enabled; /* flag in option struct that enables method */ 361 int *batch_flag; /* flag in option struct that disables method */ 362 }; 363 364 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 365 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 366 static int input_userauth_success(int, u_int32_t, struct ssh *); 367 static int input_userauth_failure(int, u_int32_t, struct ssh *); 368 static int input_userauth_banner(int, u_int32_t, struct ssh *); 369 static int input_userauth_error(int, u_int32_t, struct ssh *); 370 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 371 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 372 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 373 374 static int userauth_none(struct ssh *); 375 static int userauth_pubkey(struct ssh *); 376 static int userauth_passwd(struct ssh *); 377 static int userauth_kbdint(struct ssh *); 378 static int userauth_hostbased(struct ssh *); 379 380 #ifdef GSSAPI 381 static int userauth_gssapi(struct ssh *); 382 static void userauth_gssapi_cleanup(struct ssh *); 383 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 384 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 385 static int input_gssapi_error(int, u_int32_t, struct ssh *); 386 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 387 #endif 388 389 void userauth(struct ssh *, char *); 390 391 static void pubkey_cleanup(struct ssh *); 392 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 393 static void pubkey_prepare(Authctxt *); 394 static void pubkey_reset(Authctxt *); 395 static struct sshkey *load_identity_file(Identity *); 396 397 static Authmethod *authmethod_get(char *authlist); 398 static Authmethod *authmethod_lookup(const char *name); 399 static char *authmethods_get(void); 400 401 Authmethod authmethods[] = { 402 #ifdef GSSAPI 403 {"gssapi-with-mic", 404 userauth_gssapi, 405 userauth_gssapi_cleanup, 406 &options.gss_authentication, 407 NULL}, 408 #endif 409 {"hostbased", 410 userauth_hostbased, 411 NULL, 412 &options.hostbased_authentication, 413 NULL}, 414 {"publickey", 415 userauth_pubkey, 416 NULL, 417 &options.pubkey_authentication, 418 NULL}, 419 {"keyboard-interactive", 420 userauth_kbdint, 421 NULL, 422 &options.kbd_interactive_authentication, 423 &options.batch_mode}, 424 {"password", 425 userauth_passwd, 426 NULL, 427 &options.password_authentication, 428 &options.batch_mode}, 429 {"none", 430 userauth_none, 431 NULL, 432 NULL, 433 NULL}, 434 {NULL, NULL, NULL, NULL, NULL} 435 }; 436 437 void 438 ssh_userauth2(struct ssh *ssh, const char *local_user, 439 const char *server_user, char *host, Sensitive *sensitive) 440 { 441 Authctxt authctxt; 442 int r; 443 444 if (options.challenge_response_authentication) 445 options.kbd_interactive_authentication = 1; 446 if (options.preferred_authentications == NULL) 447 options.preferred_authentications = authmethods_get(); 448 449 /* setup authentication context */ 450 memset(&authctxt, 0, sizeof(authctxt)); 451 authctxt.server_user = server_user; 452 authctxt.local_user = local_user; 453 authctxt.host = host; 454 authctxt.service = "ssh-connection"; /* service name */ 455 authctxt.success = 0; 456 authctxt.method = authmethod_lookup("none"); 457 authctxt.authlist = NULL; 458 authctxt.methoddata = NULL; 459 authctxt.sensitive = sensitive; 460 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 461 authctxt.info_req_seen = 0; 462 authctxt.attempt_kbdint = 0; 463 authctxt.attempt_passwd = 0; 464 #if GSSAPI 465 authctxt.gss_supported_mechs = NULL; 466 authctxt.mech_tried = 0; 467 #endif 468 authctxt.agent_fd = -1; 469 pubkey_prepare(&authctxt); 470 if (authctxt.method == NULL) { 471 fatal_f("internal error: cannot send userauth none request"); 472 } 473 474 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 475 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 476 (r = sshpkt_send(ssh)) != 0) 477 fatal_fr(r, "send packet"); 478 479 ssh->authctxt = &authctxt; 480 ssh_dispatch_init(ssh, &input_userauth_error); 481 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 482 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 483 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 484 pubkey_cleanup(ssh); 485 ssh->authctxt = NULL; 486 487 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 488 489 if (!authctxt.success) 490 fatal("Authentication failed."); 491 debug("Authentication succeeded (%s).", authctxt.method->name); 492 } 493 494 /* ARGSUSED */ 495 static int 496 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 497 { 498 int r; 499 500 if (ssh_packet_remaining(ssh) > 0) { 501 char *reply; 502 503 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 504 goto out; 505 debug2("service_accept: %s", reply); 506 free(reply); 507 } else { 508 debug2("buggy server: service_accept w/o service"); 509 } 510 if ((r = sshpkt_get_end(ssh)) != 0) 511 goto out; 512 debug("SSH2_MSG_SERVICE_ACCEPT received"); 513 514 /* initial userauth request */ 515 userauth_none(ssh); 516 517 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 519 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 520 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 521 r = 0; 522 out: 523 return r; 524 } 525 526 /* ARGSUSED */ 527 static int 528 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 529 { 530 return kex_input_ext_info(type, seqnr, ssh); 531 } 532 533 void 534 userauth(struct ssh *ssh, char *authlist) 535 { 536 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 537 538 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 539 authctxt->method->cleanup(ssh); 540 541 free(authctxt->methoddata); 542 authctxt->methoddata = NULL; 543 if (authlist == NULL) { 544 authlist = authctxt->authlist; 545 } else { 546 free(authctxt->authlist); 547 authctxt->authlist = authlist; 548 } 549 for (;;) { 550 Authmethod *method = authmethod_get(authlist); 551 if (method == NULL) 552 fatal("%s@%s: Permission denied (%s).", 553 authctxt->server_user, authctxt->host, authlist); 554 authctxt->method = method; 555 556 /* reset the per method handler */ 557 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 558 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 559 560 /* and try new method */ 561 if (method->userauth(ssh) != 0) { 562 debug2("we sent a %s packet, wait for reply", method->name); 563 break; 564 } else { 565 debug2("we did not send a packet, disable method"); 566 method->enabled = NULL; 567 } 568 } 569 } 570 571 /* ARGSUSED */ 572 static int 573 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 574 { 575 fatal_f("bad message during authentication: type %d", type); 576 return 0; 577 } 578 579 /* ARGSUSED */ 580 static int 581 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 582 { 583 char *msg = NULL; 584 size_t len; 585 int r; 586 587 debug3_f("entering"); 588 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 589 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 590 goto out; 591 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 592 fmprintf(stderr, "%s", msg); 593 r = 0; 594 out: 595 free(msg); 596 return r; 597 } 598 599 /* ARGSUSED */ 600 static int 601 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 602 { 603 Authctxt *authctxt = ssh->authctxt; 604 605 if (authctxt == NULL) 606 fatal_f("no authentication context"); 607 free(authctxt->authlist); 608 authctxt->authlist = NULL; 609 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 610 authctxt->method->cleanup(ssh); 611 free(authctxt->methoddata); 612 authctxt->methoddata = NULL; 613 authctxt->success = 1; /* break out */ 614 return 0; 615 } 616 617 #if 0 618 static int 619 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 620 { 621 Authctxt *authctxt = ssh->authctxt; 622 623 if (authctxt == NULL) 624 fatal_f("no authentication context"); 625 626 fatal("Unexpected authentication success during %s.", 627 authctxt->method->name); 628 return 0; 629 } 630 #endif 631 632 /* ARGSUSED */ 633 static int 634 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 635 { 636 Authctxt *authctxt = ssh->authctxt; 637 char *authlist = NULL; 638 u_char partial; 639 640 if (authctxt == NULL) 641 fatal("input_userauth_failure: no authentication context"); 642 643 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 644 sshpkt_get_u8(ssh, &partial) != 0 || 645 sshpkt_get_end(ssh) != 0) 646 goto out; 647 648 if (partial != 0) { 649 verbose("Authenticated with partial success."); 650 /* reset state */ 651 pubkey_reset(authctxt); 652 } 653 debug("Authentications that can continue: %s", authlist); 654 655 userauth(ssh, authlist); 656 authlist = NULL; 657 out: 658 free(authlist); 659 return 0; 660 } 661 662 /* 663 * Format an identity for logging including filename, key type, fingerprint 664 * and location (agent, etc.). Caller must free. 665 */ 666 static char * 667 format_identity(Identity *id) 668 { 669 char *fp = NULL, *ret = NULL; 670 const char *note = ""; 671 672 if (id->key != NULL) { 673 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 674 SSH_FP_DEFAULT); 675 } 676 if (id->key) { 677 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 678 note = " token"; 679 else if (sshkey_is_sk(id->key)) 680 note = " authenticator"; 681 } 682 xasprintf(&ret, "%s %s%s%s%s%s%s", 683 id->filename, 684 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 685 fp ? fp : "", 686 id->userprovided ? " explicit" : "", note, 687 id->agent_fd != -1 ? " agent" : ""); 688 free(fp); 689 return ret; 690 } 691 692 /* ARGSUSED */ 693 static int 694 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 695 { 696 Authctxt *authctxt = ssh->authctxt; 697 struct sshkey *key = NULL; 698 Identity *id = NULL; 699 int pktype, found = 0, sent = 0; 700 size_t blen; 701 char *pkalg = NULL, *fp = NULL, *ident = NULL; 702 u_char *pkblob = NULL; 703 int r; 704 705 if (authctxt == NULL) 706 fatal("input_userauth_pk_ok: no authentication context"); 707 708 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 709 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 710 (r = sshpkt_get_end(ssh)) != 0) 711 goto done; 712 713 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 714 debug_f("server sent unknown pkalg %s", pkalg); 715 goto done; 716 } 717 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 718 debug_r(r, "no key from blob. pkalg %s", pkalg); 719 goto done; 720 } 721 if (key->type != pktype) { 722 error("input_userauth_pk_ok: type mismatch " 723 "for decoded key (received %d, expected %d)", 724 key->type, pktype); 725 goto done; 726 } 727 728 /* 729 * search keys in the reverse order, because last candidate has been 730 * moved to the end of the queue. this also avoids confusion by 731 * duplicate keys 732 */ 733 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 734 if (sshkey_equal(key, id->key)) { 735 found = 1; 736 break; 737 } 738 } 739 if (!found || id == NULL) { 740 fp = sshkey_fingerprint(key, options.fingerprint_hash, 741 SSH_FP_DEFAULT); 742 error_f("server replied with unknown key: %s %s", 743 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 744 goto done; 745 } 746 ident = format_identity(id); 747 debug("Server accepts key: %s", ident); 748 sent = sign_and_send_pubkey(ssh, id); 749 r = 0; 750 done: 751 sshkey_free(key); 752 free(ident); 753 free(fp); 754 free(pkalg); 755 free(pkblob); 756 757 /* try another method if we did not send a packet */ 758 if (r == 0 && sent == 0) 759 userauth(ssh, NULL); 760 return r; 761 } 762 763 #ifdef GSSAPI 764 static int 765 userauth_gssapi(struct ssh *ssh) 766 { 767 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 768 Gssctxt *gssctxt = NULL; 769 OM_uint32 min; 770 int r, ok = 0; 771 gss_OID mech = NULL; 772 773 /* Try one GSSAPI method at a time, rather than sending them all at 774 * once. */ 775 776 if (authctxt->gss_supported_mechs == NULL) 777 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 778 779 /* Check to see whether the mechanism is usable before we offer it */ 780 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 781 !ok) { 782 mech = &authctxt->gss_supported_mechs-> 783 elements[authctxt->mech_tried]; 784 /* My DER encoding requires length<128 */ 785 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 786 mech, authctxt->host)) { 787 ok = 1; /* Mechanism works */ 788 } else { 789 authctxt->mech_tried++; 790 } 791 } 792 793 if (!ok || mech == NULL) 794 return 0; 795 796 authctxt->methoddata=(void *)gssctxt; 797 798 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 799 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 800 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 801 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 802 (r = sshpkt_put_u32(ssh, 1)) != 0 || 803 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 804 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 805 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 806 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 807 (r = sshpkt_send(ssh)) != 0) 808 fatal_fr(r, "send packet"); 809 810 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 811 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 812 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 813 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 814 815 authctxt->mech_tried++; /* Move along to next candidate */ 816 817 return 1; 818 } 819 820 static void 821 userauth_gssapi_cleanup(struct ssh *ssh) 822 { 823 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 824 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 825 826 ssh_gssapi_delete_ctx(&gssctxt); 827 authctxt->methoddata = NULL; 828 829 free(authctxt->gss_supported_mechs); 830 authctxt->gss_supported_mechs = NULL; 831 } 832 833 static OM_uint32 834 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 835 { 836 Authctxt *authctxt = ssh->authctxt; 837 Gssctxt *gssctxt = authctxt->methoddata; 838 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 839 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 840 gss_buffer_desc gssbuf; 841 OM_uint32 status, ms, flags; 842 int r; 843 844 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 845 recv_tok, &send_tok, &flags); 846 847 if (send_tok.length > 0) { 848 u_char type = GSS_ERROR(status) ? 849 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 850 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 851 852 if ((r = sshpkt_start(ssh, type)) != 0 || 853 (r = sshpkt_put_string(ssh, send_tok.value, 854 send_tok.length)) != 0 || 855 (r = sshpkt_send(ssh)) != 0) 856 fatal_fr(r, "send %u packet", type); 857 858 gss_release_buffer(&ms, &send_tok); 859 } 860 861 if (status == GSS_S_COMPLETE) { 862 /* send either complete or MIC, depending on mechanism */ 863 if (!(flags & GSS_C_INTEG_FLAG)) { 864 if ((r = sshpkt_start(ssh, 865 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 866 (r = sshpkt_send(ssh)) != 0) 867 fatal_fr(r, "send completion"); 868 } else { 869 struct sshbuf *b; 870 871 if ((b = sshbuf_new()) == NULL) 872 fatal_f("sshbuf_new failed"); 873 ssh_gssapi_buildmic(b, authctxt->server_user, 874 authctxt->service, "gssapi-with-mic"); 875 876 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 877 fatal_f("sshbuf_mutable_ptr failed"); 878 gssbuf.length = sshbuf_len(b); 879 880 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 881 882 if (!GSS_ERROR(status)) { 883 if ((r = sshpkt_start(ssh, 884 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 885 (r = sshpkt_put_string(ssh, mic.value, 886 mic.length)) != 0 || 887 (r = sshpkt_send(ssh)) != 0) 888 fatal_fr(r, "send MIC"); 889 } 890 891 sshbuf_free(b); 892 gss_release_buffer(&ms, &mic); 893 } 894 } 895 896 return status; 897 } 898 899 /* ARGSUSED */ 900 static int 901 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 902 { 903 Authctxt *authctxt = ssh->authctxt; 904 Gssctxt *gssctxt; 905 size_t oidlen; 906 u_char *oidv = NULL; 907 int r; 908 909 if (authctxt == NULL) 910 fatal("input_gssapi_response: no authentication context"); 911 gssctxt = authctxt->methoddata; 912 913 /* Setup our OID */ 914 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 915 goto done; 916 917 if (oidlen <= 2 || 918 oidv[0] != SSH_GSS_OIDTYPE || 919 oidv[1] != oidlen - 2) { 920 debug("Badly encoded mechanism OID received"); 921 userauth(ssh, NULL); 922 goto ok; 923 } 924 925 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 926 fatal("Server returned different OID than expected"); 927 928 if ((r = sshpkt_get_end(ssh)) != 0) 929 goto done; 930 931 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 932 /* Start again with next method on list */ 933 debug("Trying to start again"); 934 userauth(ssh, NULL); 935 goto ok; 936 } 937 ok: 938 r = 0; 939 done: 940 free(oidv); 941 return r; 942 } 943 944 /* ARGSUSED */ 945 static int 946 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 947 { 948 Authctxt *authctxt = ssh->authctxt; 949 gss_buffer_desc recv_tok; 950 u_char *p = NULL; 951 size_t len; 952 OM_uint32 status; 953 int r; 954 955 if (authctxt == NULL) 956 fatal("input_gssapi_response: no authentication context"); 957 958 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 959 (r = sshpkt_get_end(ssh)) != 0) 960 goto out; 961 962 recv_tok.value = p; 963 recv_tok.length = len; 964 status = process_gssapi_token(ssh, &recv_tok); 965 966 /* Start again with the next method in the list */ 967 if (GSS_ERROR(status)) { 968 userauth(ssh, NULL); 969 /* ok */ 970 } 971 r = 0; 972 out: 973 free(p); 974 return r; 975 } 976 977 /* ARGSUSED */ 978 static int 979 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 980 { 981 Authctxt *authctxt = ssh->authctxt; 982 Gssctxt *gssctxt; 983 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 984 gss_buffer_desc recv_tok; 985 OM_uint32 ms; 986 u_char *p = NULL; 987 size_t len; 988 int r; 989 990 if (authctxt == NULL) 991 fatal("input_gssapi_response: no authentication context"); 992 gssctxt = authctxt->methoddata; 993 994 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 995 (r = sshpkt_get_end(ssh)) != 0) { 996 free(p); 997 return r; 998 } 999 1000 /* Stick it into GSSAPI and see what it says */ 1001 recv_tok.value = p; 1002 recv_tok.length = len; 1003 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1004 &recv_tok, &send_tok, NULL); 1005 free(p); 1006 gss_release_buffer(&ms, &send_tok); 1007 1008 /* Server will be returning a failed packet after this one */ 1009 return 0; 1010 } 1011 1012 /* ARGSUSED */ 1013 static int 1014 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1015 { 1016 char *msg = NULL; 1017 char *lang = NULL; 1018 int r; 1019 1020 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1021 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1022 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1023 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1024 goto out; 1025 r = sshpkt_get_end(ssh); 1026 debug("Server GSSAPI Error:\n%s", msg); 1027 out: 1028 free(msg); 1029 free(lang); 1030 return r; 1031 } 1032 #endif /* GSSAPI */ 1033 1034 static int 1035 userauth_none(struct ssh *ssh) 1036 { 1037 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1038 int r; 1039 1040 /* initial userauth request */ 1041 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1042 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1043 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1044 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1045 (r = sshpkt_send(ssh)) != 0) 1046 fatal_fr(r, "send packet"); 1047 return 1; 1048 } 1049 1050 static int 1051 userauth_passwd(struct ssh *ssh) 1052 { 1053 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1054 char *password, *prompt = NULL; 1055 const char *host = options.host_key_alias ? options.host_key_alias : 1056 authctxt->host; 1057 int r; 1058 1059 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1060 return 0; 1061 1062 if (authctxt->attempt_passwd != 1) 1063 error("Permission denied, please try again."); 1064 1065 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1066 password = read_passphrase(prompt, 0); 1067 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1068 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1069 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1070 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1071 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1072 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1073 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1074 (r = sshpkt_send(ssh)) != 0) 1075 fatal_fr(r, "send packet"); 1076 1077 free(prompt); 1078 if (password != NULL) 1079 freezero(password, strlen(password)); 1080 1081 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1082 &input_userauth_passwd_changereq); 1083 1084 return 1; 1085 } 1086 1087 /* 1088 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1089 */ 1090 /* ARGSUSED */ 1091 static int 1092 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1093 { 1094 Authctxt *authctxt = ssh->authctxt; 1095 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1096 char prompt[256]; 1097 const char *host; 1098 int r; 1099 1100 debug2("input_userauth_passwd_changereq"); 1101 1102 if (authctxt == NULL) 1103 fatal("input_userauth_passwd_changereq: " 1104 "no authentication context"); 1105 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1106 1107 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1108 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1109 goto out; 1110 if (strlen(info) > 0) 1111 logit("%s", info); 1112 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1113 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1114 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1115 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1116 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1117 goto out; 1118 1119 snprintf(prompt, sizeof(prompt), 1120 "Enter %.30s@%.128s's old password: ", 1121 authctxt->server_user, host); 1122 password = read_passphrase(prompt, 0); 1123 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1124 goto out; 1125 1126 freezero(password, strlen(password)); 1127 password = NULL; 1128 while (password == NULL) { 1129 snprintf(prompt, sizeof(prompt), 1130 "Enter %.30s@%.128s's new password: ", 1131 authctxt->server_user, host); 1132 password = read_passphrase(prompt, RP_ALLOW_EOF); 1133 if (password == NULL) { 1134 /* bail out */ 1135 r = 0; 1136 goto out; 1137 } 1138 snprintf(prompt, sizeof(prompt), 1139 "Retype %.30s@%.128s's new password: ", 1140 authctxt->server_user, host); 1141 retype = read_passphrase(prompt, 0); 1142 if (strcmp(password, retype) != 0) { 1143 freezero(password, strlen(password)); 1144 logit("Mismatch; try again, EOF to quit."); 1145 password = NULL; 1146 } 1147 freezero(retype, strlen(retype)); 1148 } 1149 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1150 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1151 (r = sshpkt_send(ssh)) != 0) 1152 goto out; 1153 1154 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1155 &input_userauth_passwd_changereq); 1156 r = 0; 1157 out: 1158 if (password) 1159 freezero(password, strlen(password)); 1160 free(info); 1161 free(lang); 1162 return r; 1163 } 1164 1165 /* 1166 * Select an algorithm for publickey signatures. 1167 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1168 * 1169 * Call with ssh==NULL to ignore server-sig-algs extension list and 1170 * only attempt with the key's base signature type. 1171 */ 1172 static char * 1173 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1174 { 1175 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1176 1177 /* 1178 * The signature algorithm will only differ from the key algorithm 1179 * for RSA keys/certs and when the server advertises support for 1180 * newer (SHA2) algorithms. 1181 */ 1182 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1183 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1184 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1185 /* Filter base key signature alg against our configuration */ 1186 return match_list(sshkey_ssh_name(key), 1187 options.pubkey_key_types, NULL); 1188 } 1189 1190 /* 1191 * For RSA keys/certs, since these might have a different sig type: 1192 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1193 * that also appears in the supported signature algorithms list from 1194 * the server. 1195 */ 1196 oallowed = allowed = xstrdup(options.pubkey_key_types); 1197 while ((cp = strsep(&allowed, ",")) != NULL) { 1198 if (sshkey_type_from_name(cp) != key->type) 1199 continue; 1200 tmp = match_list(sshkey_sigalg_by_name(cp), 1201 ssh->kex->server_sig_algs, NULL); 1202 if (tmp != NULL) 1203 alg = xstrdup(cp); 1204 free(tmp); 1205 if (alg != NULL) 1206 break; 1207 } 1208 free(oallowed); 1209 return alg; 1210 } 1211 1212 static int 1213 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1214 const u_char *data, size_t datalen, u_int compat, const char *alg) 1215 { 1216 struct sshkey *sign_key = NULL, *prv = NULL; 1217 int r = SSH_ERR_INTERNAL_ERROR; 1218 struct notifier_ctx *notifier = NULL; 1219 char *fp = NULL, *pin = NULL, *prompt = NULL; 1220 1221 *sigp = NULL; 1222 *lenp = 0; 1223 1224 /* The agent supports this key. */ 1225 if (id->key != NULL && id->agent_fd != -1) { 1226 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1227 data, datalen, alg, compat); 1228 } 1229 1230 /* 1231 * We have already loaded the private key or the private key is 1232 * stored in external hardware. 1233 */ 1234 if (id->key != NULL && 1235 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1236 sign_key = id->key; 1237 } else { 1238 /* Load the private key from the file. */ 1239 if ((prv = load_identity_file(id)) == NULL) 1240 return SSH_ERR_KEY_NOT_FOUND; 1241 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1242 error_f("private key %s contents do not match public", 1243 id->filename); 1244 r = SSH_ERR_KEY_NOT_FOUND; 1245 goto out; 1246 } 1247 sign_key = prv; 1248 if (sshkey_is_sk(sign_key)) { 1249 if ((sign_key->sk_flags & 1250 SSH_SK_USER_VERIFICATION_REQD)) { 1251 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1252 sshkey_type(sign_key), id->filename); 1253 pin = read_passphrase(prompt, 0); 1254 } 1255 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1256 /* XXX should batch mode just skip these? */ 1257 if ((fp = sshkey_fingerprint(sign_key, 1258 options.fingerprint_hash, 1259 SSH_FP_DEFAULT)) == NULL) 1260 fatal_f("fingerprint failed"); 1261 notifier = notify_start(options.batch_mode, 1262 "Confirm user presence for key %s %s", 1263 sshkey_type(sign_key), fp); 1264 free(fp); 1265 } 1266 } 1267 } 1268 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1269 alg, options.sk_provider, pin, compat)) != 0) { 1270 debug_fr(r, "sshkey_sign"); 1271 goto out; 1272 } 1273 /* 1274 * PKCS#11 tokens may not support all signature algorithms, 1275 * so check what we get back. 1276 */ 1277 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1278 debug_fr(r, "sshkey_check_sigtype"); 1279 goto out; 1280 } 1281 /* success */ 1282 r = 0; 1283 out: 1284 free(prompt); 1285 if (pin != NULL) 1286 freezero(pin, strlen(pin)); 1287 notify_complete(notifier, "User presence confirmed"); 1288 sshkey_free(prv); 1289 return r; 1290 } 1291 1292 static int 1293 id_filename_matches(Identity *id, Identity *private_id) 1294 { 1295 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1296 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1297 size_t i, slen; 1298 1299 if (strcmp(id->filename, private_id->filename) == 0) 1300 return 1; 1301 for (i = 0; suffixes[i]; i++) { 1302 slen = strlen(suffixes[i]); 1303 if (len > slen && plen == len - slen && 1304 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1305 memcmp(id->filename, private_id->filename, plen) == 0) 1306 return 1; 1307 } 1308 return 0; 1309 } 1310 1311 static int 1312 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1313 { 1314 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1315 struct sshbuf *b = NULL; 1316 Identity *private_id, *sign_id = NULL; 1317 u_char *signature = NULL; 1318 size_t slen = 0, skip = 0; 1319 int r, fallback_sigtype, sent = 0; 1320 char *alg = NULL, *fp = NULL; 1321 const char *loc = ""; 1322 1323 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1324 SSH_FP_DEFAULT)) == NULL) 1325 return 0; 1326 1327 debug3_f("%s %s", sshkey_type(id->key), fp); 1328 1329 /* 1330 * If the key is an certificate, try to find a matching private key 1331 * and use it to complete the signature. 1332 * If no such private key exists, fall back to trying the certificate 1333 * key itself in case it has a private half already loaded. 1334 * This will try to set sign_id to the private key that will perform 1335 * the signature. 1336 */ 1337 if (sshkey_is_cert(id->key)) { 1338 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1339 if (sshkey_equal_public(id->key, private_id->key) && 1340 id->key->type != private_id->key->type) { 1341 sign_id = private_id; 1342 break; 1343 } 1344 } 1345 /* 1346 * Exact key matches are preferred, but also allow 1347 * filename matches for non-PKCS#11/agent keys that 1348 * didn't load public keys. This supports the case 1349 * of keeping just a private key file and public 1350 * certificate on disk. 1351 */ 1352 if (sign_id == NULL && 1353 !id->isprivate && id->agent_fd == -1 && 1354 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1355 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1356 if (private_id->key == NULL && 1357 id_filename_matches(id, private_id)) { 1358 sign_id = private_id; 1359 break; 1360 } 1361 } 1362 } 1363 if (sign_id != NULL) { 1364 debug2_f("using private key \"%s\"%s for " 1365 "certificate", id->filename, 1366 id->agent_fd != -1 ? " from agent" : ""); 1367 } else { 1368 debug_f("no separate private key for certificate " 1369 "\"%s\"", id->filename); 1370 } 1371 } 1372 1373 /* 1374 * If the above didn't select another identity to do the signing 1375 * then default to the one we started with. 1376 */ 1377 if (sign_id == NULL) 1378 sign_id = id; 1379 1380 /* assemble and sign data */ 1381 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1382 free(alg); 1383 slen = 0; 1384 signature = NULL; 1385 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1386 id->key)) == NULL) { 1387 error_f("no mutual signature supported"); 1388 goto out; 1389 } 1390 debug3_f("signing using %s %s", alg, fp); 1391 1392 sshbuf_free(b); 1393 if ((b = sshbuf_new()) == NULL) 1394 fatal_f("sshbuf_new failed"); 1395 if (datafellows & SSH_OLD_SESSIONID) { 1396 if ((r = sshbuf_put(b, session_id2, 1397 session_id2_len)) != 0) 1398 fatal_fr(r, "sshbuf_put"); 1399 } else { 1400 if ((r = sshbuf_put_string(b, session_id2, 1401 session_id2_len)) != 0) 1402 fatal_fr(r, "sshbuf_put_string"); 1403 } 1404 skip = sshbuf_len(b); 1405 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1406 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1407 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1408 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1409 (r = sshbuf_put_u8(b, 1)) != 0 || 1410 (r = sshbuf_put_cstring(b, alg)) != 0 || 1411 (r = sshkey_puts(id->key, b)) != 0) { 1412 fatal_fr(r, "assemble signed data"); 1413 } 1414 1415 /* generate signature */ 1416 r = identity_sign(sign_id, &signature, &slen, 1417 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1418 if (r == 0) 1419 break; 1420 else if (r == SSH_ERR_KEY_NOT_FOUND) 1421 goto out; /* soft failure */ 1422 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1423 !fallback_sigtype) { 1424 if (sign_id->agent_fd != -1) 1425 loc = "agent "; 1426 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1427 loc = "token "; 1428 logit("%skey %s %s returned incorrect signature type", 1429 loc, sshkey_type(id->key), fp); 1430 continue; 1431 } 1432 error_fr(r, "signing failed for %s \"%s\"%s", 1433 sshkey_type(sign_id->key), sign_id->filename, 1434 id->agent_fd != -1 ? " from agent" : ""); 1435 goto out; 1436 } 1437 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1438 fatal_f("no signature"); 1439 1440 /* append signature */ 1441 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1442 fatal_fr(r, "append signature"); 1443 1444 #ifdef DEBUG_PK 1445 sshbuf_dump(b, stderr); 1446 #endif 1447 /* skip session id and packet type */ 1448 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1449 fatal_fr(r, "consume"); 1450 1451 /* put remaining data from buffer into packet */ 1452 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1453 (r = sshpkt_putb(ssh, b)) != 0 || 1454 (r = sshpkt_send(ssh)) != 0) 1455 fatal_fr(r, "enqueue request"); 1456 1457 /* success */ 1458 sent = 1; 1459 1460 out: 1461 free(fp); 1462 free(alg); 1463 sshbuf_free(b); 1464 freezero(signature, slen); 1465 return sent; 1466 } 1467 1468 static int 1469 send_pubkey_test(struct ssh *ssh, Identity *id) 1470 { 1471 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1472 u_char *blob = NULL; 1473 char *alg = NULL; 1474 size_t bloblen; 1475 u_int have_sig = 0; 1476 int sent = 0, r; 1477 1478 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1479 debug_f("no mutual signature algorithm"); 1480 goto out; 1481 } 1482 1483 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1484 /* we cannot handle this key */ 1485 debug3_f("cannot handle key"); 1486 goto out; 1487 } 1488 /* register callback for USERAUTH_PK_OK message */ 1489 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1490 1491 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1492 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1493 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1494 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1495 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1496 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1497 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1498 (r = sshpkt_send(ssh)) != 0) 1499 fatal_fr(r, "send packet"); 1500 sent = 1; 1501 1502 out: 1503 free(alg); 1504 free(blob); 1505 return sent; 1506 } 1507 1508 static struct sshkey * 1509 load_identity_file(Identity *id) 1510 { 1511 struct sshkey *private = NULL; 1512 char prompt[300], *passphrase, *comment; 1513 int r, quit = 0, i; 1514 struct stat st; 1515 1516 if (stat(id->filename, &st) == -1) { 1517 do_log2(id->userprovided ? 1518 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1519 "no such identity: %s: %s", id->filename, strerror(errno)); 1520 return NULL; 1521 } 1522 snprintf(prompt, sizeof prompt, 1523 "Enter passphrase for key '%.100s': ", id->filename); 1524 for (i = 0; i <= options.number_of_password_prompts; i++) { 1525 if (i == 0) 1526 passphrase = ""; 1527 else { 1528 passphrase = read_passphrase(prompt, 0); 1529 if (*passphrase == '\0') { 1530 debug2("no passphrase given, try next key"); 1531 free(passphrase); 1532 break; 1533 } 1534 } 1535 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1536 passphrase, &private, &comment))) { 1537 case 0: 1538 break; 1539 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1540 if (options.batch_mode) { 1541 quit = 1; 1542 break; 1543 } 1544 if (i != 0) 1545 debug2("bad passphrase given, try again..."); 1546 break; 1547 case SSH_ERR_SYSTEM_ERROR: 1548 if (errno == ENOENT) { 1549 debug2_r(r, "Load key \"%s\"", id->filename); 1550 quit = 1; 1551 break; 1552 } 1553 /* FALLTHROUGH */ 1554 default: 1555 error_r(r, "Load key \"%s\"", id->filename); 1556 quit = 1; 1557 break; 1558 } 1559 if (private != NULL && sshkey_is_sk(private) && 1560 options.sk_provider == NULL) { 1561 debug("key \"%s\" is an authenticator-hosted key, " 1562 "but no provider specified", id->filename); 1563 sshkey_free(private); 1564 private = NULL; 1565 quit = 1; 1566 } 1567 if (!quit && private != NULL && id->agent_fd == -1 && 1568 !(id->key && id->isprivate)) 1569 maybe_add_key_to_agent(id->filename, private, comment, 1570 passphrase); 1571 if (i > 0) 1572 freezero(passphrase, strlen(passphrase)); 1573 free(comment); 1574 if (private != NULL || quit) 1575 break; 1576 } 1577 return private; 1578 } 1579 1580 static int 1581 key_type_allowed_by_config(struct sshkey *key) 1582 { 1583 if (match_pattern_list(sshkey_ssh_name(key), 1584 options.pubkey_key_types, 0) == 1) 1585 return 1; 1586 1587 /* RSA keys/certs might be allowed by alternate signature types */ 1588 switch (key->type) { 1589 case KEY_RSA: 1590 if (match_pattern_list("rsa-sha2-512", 1591 options.pubkey_key_types, 0) == 1) 1592 return 1; 1593 if (match_pattern_list("rsa-sha2-256", 1594 options.pubkey_key_types, 0) == 1) 1595 return 1; 1596 break; 1597 case KEY_RSA_CERT: 1598 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1599 options.pubkey_key_types, 0) == 1) 1600 return 1; 1601 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1602 options.pubkey_key_types, 0) == 1) 1603 return 1; 1604 break; 1605 } 1606 return 0; 1607 } 1608 1609 1610 /* 1611 * try keys in the following order: 1612 * 1. certificates listed in the config file 1613 * 2. other input certificates 1614 * 3. agent keys that are found in the config file 1615 * 4. other agent keys 1616 * 5. keys that are only listed in the config file 1617 */ 1618 static void 1619 pubkey_prepare(Authctxt *authctxt) 1620 { 1621 struct identity *id, *id2, *tmp; 1622 struct idlist agent, files, *preferred; 1623 struct sshkey *key; 1624 int agent_fd = -1, i, r, found; 1625 size_t j; 1626 struct ssh_identitylist *idlist; 1627 char *ident; 1628 1629 TAILQ_INIT(&agent); /* keys from the agent */ 1630 TAILQ_INIT(&files); /* keys from the config file */ 1631 preferred = &authctxt->keys; 1632 TAILQ_INIT(preferred); /* preferred order of keys */ 1633 1634 /* list of keys stored in the filesystem and PKCS#11 */ 1635 for (i = 0; i < options.num_identity_files; i++) { 1636 key = options.identity_keys[i]; 1637 if (key && key->cert && 1638 key->cert->type != SSH2_CERT_TYPE_USER) { 1639 debug_f("ignoring certificate %s: not a user " 1640 "certificate", options.identity_files[i]); 1641 continue; 1642 } 1643 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1644 debug_f("ignoring authenticator-hosted key %s as no " 1645 "SecurityKeyProvider has been specified", 1646 options.identity_files[i]); 1647 continue; 1648 } 1649 options.identity_keys[i] = NULL; 1650 id = xcalloc(1, sizeof(*id)); 1651 id->agent_fd = -1; 1652 id->key = key; 1653 id->filename = xstrdup(options.identity_files[i]); 1654 id->userprovided = options.identity_file_userprovided[i]; 1655 TAILQ_INSERT_TAIL(&files, id, next); 1656 } 1657 /* list of certificates specified by user */ 1658 for (i = 0; i < options.num_certificate_files; i++) { 1659 key = options.certificates[i]; 1660 if (!sshkey_is_cert(key) || key->cert == NULL || 1661 key->cert->type != SSH2_CERT_TYPE_USER) { 1662 debug_f("ignoring certificate %s: not a user " 1663 "certificate", options.identity_files[i]); 1664 continue; 1665 } 1666 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1667 debug_f("ignoring authenticator-hosted key " 1668 "certificate %s as no " 1669 "SecurityKeyProvider has been specified", 1670 options.identity_files[i]); 1671 continue; 1672 } 1673 id = xcalloc(1, sizeof(*id)); 1674 id->agent_fd = -1; 1675 id->key = key; 1676 id->filename = xstrdup(options.certificate_files[i]); 1677 id->userprovided = options.certificate_file_userprovided[i]; 1678 TAILQ_INSERT_TAIL(preferred, id, next); 1679 } 1680 /* list of keys supported by the agent */ 1681 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1682 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1683 debug_fr(r, "ssh_get_authentication_socket"); 1684 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1685 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1686 debug_fr(r, "ssh_fetch_identitylist"); 1687 close(agent_fd); 1688 } else { 1689 for (j = 0; j < idlist->nkeys; j++) { 1690 found = 0; 1691 TAILQ_FOREACH(id, &files, next) { 1692 /* 1693 * agent keys from the config file are 1694 * preferred 1695 */ 1696 if (sshkey_equal(idlist->keys[j], id->key)) { 1697 TAILQ_REMOVE(&files, id, next); 1698 TAILQ_INSERT_TAIL(preferred, id, next); 1699 id->agent_fd = agent_fd; 1700 found = 1; 1701 break; 1702 } 1703 } 1704 if (!found && !options.identities_only) { 1705 id = xcalloc(1, sizeof(*id)); 1706 /* XXX "steals" key/comment from idlist */ 1707 id->key = idlist->keys[j]; 1708 id->filename = idlist->comments[j]; 1709 idlist->keys[j] = NULL; 1710 idlist->comments[j] = NULL; 1711 id->agent_fd = agent_fd; 1712 TAILQ_INSERT_TAIL(&agent, id, next); 1713 } 1714 } 1715 ssh_free_identitylist(idlist); 1716 /* append remaining agent keys */ 1717 TAILQ_CONCAT(preferred, &agent, next); 1718 authctxt->agent_fd = agent_fd; 1719 } 1720 /* Prefer PKCS11 keys that are explicitly listed */ 1721 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1722 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1723 continue; 1724 found = 0; 1725 TAILQ_FOREACH(id2, &files, next) { 1726 if (id2->key == NULL || 1727 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1728 continue; 1729 if (sshkey_equal(id->key, id2->key)) { 1730 TAILQ_REMOVE(&files, id, next); 1731 TAILQ_INSERT_TAIL(preferred, id, next); 1732 found = 1; 1733 break; 1734 } 1735 } 1736 /* If IdentitiesOnly set and key not found then don't use it */ 1737 if (!found && options.identities_only) { 1738 TAILQ_REMOVE(&files, id, next); 1739 freezero(id, sizeof(*id)); 1740 } 1741 } 1742 /* append remaining keys from the config file */ 1743 TAILQ_CONCAT(preferred, &files, next); 1744 /* finally, filter by PubkeyAcceptedKeyTypes */ 1745 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1746 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1747 debug("Skipping %s key %s - " 1748 "not in PubkeyAcceptedKeyTypes", 1749 sshkey_ssh_name(id->key), id->filename); 1750 TAILQ_REMOVE(preferred, id, next); 1751 sshkey_free(id->key); 1752 free(id->filename); 1753 memset(id, 0, sizeof(*id)); 1754 continue; 1755 } 1756 } 1757 /* List the keys we plan on using */ 1758 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1759 ident = format_identity(id); 1760 debug("Will attempt key: %s", ident); 1761 free(ident); 1762 } 1763 debug2_f("done"); 1764 } 1765 1766 static void 1767 pubkey_cleanup(struct ssh *ssh) 1768 { 1769 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1770 Identity *id; 1771 1772 if (authctxt->agent_fd != -1) { 1773 ssh_close_authentication_socket(authctxt->agent_fd); 1774 authctxt->agent_fd = -1; 1775 } 1776 for (id = TAILQ_FIRST(&authctxt->keys); id; 1777 id = TAILQ_FIRST(&authctxt->keys)) { 1778 TAILQ_REMOVE(&authctxt->keys, id, next); 1779 sshkey_free(id->key); 1780 free(id->filename); 1781 free(id); 1782 } 1783 } 1784 1785 static void 1786 pubkey_reset(Authctxt *authctxt) 1787 { 1788 Identity *id; 1789 1790 TAILQ_FOREACH(id, &authctxt->keys, next) 1791 id->tried = 0; 1792 } 1793 1794 static int 1795 try_identity(Identity *id) 1796 { 1797 if (!id->key) 1798 return (0); 1799 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1800 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1801 debug("Skipped %s key %s for RSA/MD5 server", 1802 sshkey_type(id->key), id->filename); 1803 return (0); 1804 } 1805 return 1; 1806 } 1807 1808 static int 1809 userauth_pubkey(struct ssh *ssh) 1810 { 1811 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1812 Identity *id; 1813 int sent = 0; 1814 char *ident; 1815 1816 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1817 if (id->tried++) 1818 return (0); 1819 /* move key to the end of the queue */ 1820 TAILQ_REMOVE(&authctxt->keys, id, next); 1821 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1822 /* 1823 * send a test message if we have the public key. for 1824 * encrypted keys we cannot do this and have to load the 1825 * private key instead 1826 */ 1827 if (id->key != NULL) { 1828 if (try_identity(id)) { 1829 ident = format_identity(id); 1830 debug("Offering public key: %s", ident); 1831 free(ident); 1832 sent = send_pubkey_test(ssh, id); 1833 } 1834 } else { 1835 debug("Trying private key: %s", id->filename); 1836 id->key = load_identity_file(id); 1837 if (id->key != NULL) { 1838 if (try_identity(id)) { 1839 id->isprivate = 1; 1840 sent = sign_and_send_pubkey(ssh, id); 1841 } 1842 sshkey_free(id->key); 1843 id->key = NULL; 1844 id->isprivate = 0; 1845 } 1846 } 1847 if (sent) 1848 return (sent); 1849 } 1850 return (0); 1851 } 1852 1853 /* 1854 * Send userauth request message specifying keyboard-interactive method. 1855 */ 1856 static int 1857 userauth_kbdint(struct ssh *ssh) 1858 { 1859 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1860 int r; 1861 1862 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1863 return 0; 1864 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1865 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1866 debug3("userauth_kbdint: disable: no info_req_seen"); 1867 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1868 return 0; 1869 } 1870 1871 debug2("userauth_kbdint"); 1872 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1873 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1874 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1875 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1876 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1877 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1878 options.kbd_interactive_devices : "")) != 0 || 1879 (r = sshpkt_send(ssh)) != 0) 1880 fatal_fr(r, "send packet"); 1881 1882 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1883 return 1; 1884 } 1885 1886 /* 1887 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1888 */ 1889 static int 1890 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1891 { 1892 Authctxt *authctxt = ssh->authctxt; 1893 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1894 char *display_prompt = NULL, *response = NULL; 1895 u_char echo = 0; 1896 u_int num_prompts, i; 1897 int r; 1898 1899 debug2_f("entering"); 1900 1901 if (authctxt == NULL) 1902 fatal_f("no authentication context"); 1903 1904 authctxt->info_req_seen = 1; 1905 1906 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1907 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1908 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1909 goto out; 1910 if (strlen(name) > 0) 1911 logit("%s", name); 1912 if (strlen(inst) > 0) 1913 logit("%s", inst); 1914 1915 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1916 goto out; 1917 /* 1918 * Begin to build info response packet based on prompts requested. 1919 * We commit to providing the correct number of responses, so if 1920 * further on we run into a problem that prevents this, we have to 1921 * be sure and clean this up and send a correct error response. 1922 */ 1923 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1924 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1925 goto out; 1926 1927 debug2_f("num_prompts %d", num_prompts); 1928 for (i = 0; i < num_prompts; i++) { 1929 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1930 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1931 goto out; 1932 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1933 authctxt->server_user, options.host_key_alias ? 1934 options.host_key_alias : authctxt->host, prompt) == -1) 1935 fatal_f("asmprintf failed"); 1936 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1937 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1938 goto out; 1939 freezero(response, strlen(response)); 1940 free(prompt); 1941 free(display_prompt); 1942 display_prompt = response = prompt = NULL; 1943 } 1944 /* done with parsing incoming message. */ 1945 if ((r = sshpkt_get_end(ssh)) != 0 || 1946 (r = sshpkt_add_padding(ssh, 64)) != 0) 1947 goto out; 1948 r = sshpkt_send(ssh); 1949 out: 1950 if (response) 1951 freezero(response, strlen(response)); 1952 free(prompt); 1953 free(display_prompt); 1954 free(name); 1955 free(inst); 1956 free(lang); 1957 return r; 1958 } 1959 1960 static int 1961 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1962 const u_char *data, size_t datalen) 1963 { 1964 struct sshbuf *b; 1965 struct stat st; 1966 pid_t pid; 1967 int r, to[2], from[2], status; 1968 int sock = ssh_packet_get_connection_in(ssh); 1969 u_char rversion = 0, version = 2; 1970 void (*osigchld)(int); 1971 1972 *sigp = NULL; 1973 *lenp = 0; 1974 1975 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1976 error_f("not installed: %s", strerror(errno)); 1977 return -1; 1978 } 1979 if (fflush(stdout) != 0) { 1980 error_f("fflush: %s", strerror(errno)); 1981 return -1; 1982 } 1983 if (pipe(to) == -1) { 1984 error_f("pipe: %s", strerror(errno)); 1985 return -1; 1986 } 1987 if (pipe(from) == -1) { 1988 error_f("pipe: %s", strerror(errno)); 1989 return -1; 1990 } 1991 if ((pid = fork()) == -1) { 1992 error_f("fork: %s", strerror(errno)); 1993 return -1; 1994 } 1995 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1996 if (pid == 0) { 1997 close(from[0]); 1998 if (dup2(from[1], STDOUT_FILENO) == -1) 1999 fatal_f("dup2: %s", strerror(errno)); 2000 close(to[1]); 2001 if (dup2(to[0], STDIN_FILENO) == -1) 2002 fatal_f("dup2: %s", strerror(errno)); 2003 close(from[1]); 2004 close(to[0]); 2005 2006 if (dup2(sock, STDERR_FILENO + 1) == -1) 2007 fatal_f("dup2: %s", strerror(errno)); 2008 sock = STDERR_FILENO + 1; 2009 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2010 closefrom(sock + 1); 2011 2012 debug3_f("[child] pid=%ld, exec %s", 2013 (long)getpid(), _PATH_SSH_KEY_SIGN); 2014 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2015 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2016 strerror(errno)); 2017 } 2018 close(from[1]); 2019 close(to[0]); 2020 sock = STDERR_FILENO + 1; 2021 2022 if ((b = sshbuf_new()) == NULL) 2023 fatal_f("sshbuf_new failed"); 2024 /* send # of sock, data to be signed */ 2025 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2026 (r = sshbuf_put_string(b, data, datalen)) != 0) 2027 fatal_fr(r, "buffer error"); 2028 if (ssh_msg_send(to[1], version, b) == -1) 2029 fatal_f("couldn't send request"); 2030 sshbuf_reset(b); 2031 r = ssh_msg_recv(from[0], b); 2032 close(from[0]); 2033 close(to[1]); 2034 if (r < 0) { 2035 error_f("no reply"); 2036 goto fail; 2037 } 2038 2039 errno = 0; 2040 while (waitpid(pid, &status, 0) == -1) { 2041 if (errno != EINTR) { 2042 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2043 goto fail; 2044 } 2045 } 2046 if (!WIFEXITED(status)) { 2047 error_f("exited abnormally"); 2048 goto fail; 2049 } 2050 if (WEXITSTATUS(status) != 0) { 2051 error_f("exited with status %d", WEXITSTATUS(status)); 2052 goto fail; 2053 } 2054 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2055 error_fr(r, "buffer error"); 2056 goto fail; 2057 } 2058 if (rversion != version) { 2059 error_f("bad version"); 2060 goto fail; 2061 } 2062 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2063 error_fr(r, "buffer error"); 2064 fail: 2065 ssh_signal(SIGCHLD, osigchld); 2066 sshbuf_free(b); 2067 return -1; 2068 } 2069 ssh_signal(SIGCHLD, osigchld); 2070 sshbuf_free(b); 2071 2072 return 0; 2073 } 2074 2075 static int 2076 userauth_hostbased(struct ssh *ssh) 2077 { 2078 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2079 struct sshkey *private = NULL; 2080 struct sshbuf *b = NULL; 2081 u_char *sig = NULL, *keyblob = NULL; 2082 char *fp = NULL, *chost = NULL, *lname = NULL; 2083 size_t siglen = 0, keylen = 0; 2084 int i, r, success = 0; 2085 2086 if (authctxt->ktypes == NULL) { 2087 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2088 authctxt->ktypes = authctxt->oktypes; 2089 } 2090 2091 /* 2092 * Work through each listed type pattern in HostbasedKeyTypes, 2093 * trying each hostkey that matches the type in turn. 2094 */ 2095 for (;;) { 2096 if (authctxt->active_ktype == NULL) 2097 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2098 if (authctxt->active_ktype == NULL || 2099 *authctxt->active_ktype == '\0') 2100 break; 2101 debug3_f("trying key type %s", authctxt->active_ktype); 2102 2103 /* check for a useful key */ 2104 private = NULL; 2105 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2106 if (authctxt->sensitive->keys[i] == NULL || 2107 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2108 continue; 2109 if (match_pattern_list( 2110 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2111 authctxt->active_ktype, 0) != 1) 2112 continue; 2113 /* we take and free the key */ 2114 private = authctxt->sensitive->keys[i]; 2115 authctxt->sensitive->keys[i] = NULL; 2116 break; 2117 } 2118 /* Found one */ 2119 if (private != NULL) 2120 break; 2121 /* No more keys of this type; advance */ 2122 authctxt->active_ktype = NULL; 2123 } 2124 if (private == NULL) { 2125 free(authctxt->oktypes); 2126 authctxt->oktypes = authctxt->ktypes = NULL; 2127 authctxt->active_ktype = NULL; 2128 debug("No more client hostkeys for hostbased authentication."); 2129 goto out; 2130 } 2131 2132 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2133 SSH_FP_DEFAULT)) == NULL) { 2134 error_f("sshkey_fingerprint failed"); 2135 goto out; 2136 } 2137 debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp); 2138 2139 /* figure out a name for the client host */ 2140 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2141 if (lname == NULL) { 2142 error_f("cannot get local ipaddr/name"); 2143 goto out; 2144 } 2145 2146 /* XXX sshbuf_put_stringf? */ 2147 xasprintf(&chost, "%s.", lname); 2148 debug2_f("chost %s", chost); 2149 2150 /* construct data */ 2151 if ((b = sshbuf_new()) == NULL) { 2152 error_f("sshbuf_new failed"); 2153 goto out; 2154 } 2155 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2156 error_fr(r, "sshkey_to_blob"); 2157 goto out; 2158 } 2159 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2160 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2161 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2162 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2163 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2164 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2165 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2166 (r = sshbuf_put_cstring(b, chost)) != 0 || 2167 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2168 error_fr(r, "buffer error"); 2169 goto out; 2170 } 2171 2172 #ifdef DEBUG_PK 2173 sshbuf_dump(b, stderr); 2174 #endif 2175 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2176 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2177 error("sign using hostkey %s %s failed", 2178 sshkey_ssh_name(private), fp); 2179 goto out; 2180 } 2181 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2182 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2183 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2184 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2185 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2186 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2187 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2188 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2189 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2190 (r = sshpkt_send(ssh)) != 0) { 2191 error_fr(r, "packet error"); 2192 goto out; 2193 } 2194 success = 1; 2195 2196 out: 2197 if (sig != NULL) 2198 freezero(sig, siglen); 2199 free(keyblob); 2200 free(lname); 2201 free(fp); 2202 free(chost); 2203 sshkey_free(private); 2204 sshbuf_free(b); 2205 2206 return success; 2207 } 2208 2209 /* find auth method */ 2210 2211 /* 2212 * given auth method name, if configurable options permit this method fill 2213 * in auth_ident field and return true, otherwise return false. 2214 */ 2215 static int 2216 authmethod_is_enabled(Authmethod *method) 2217 { 2218 if (method == NULL) 2219 return 0; 2220 /* return false if options indicate this method is disabled */ 2221 if (method->enabled == NULL || *method->enabled == 0) 2222 return 0; 2223 /* return false if batch mode is enabled but method needs interactive mode */ 2224 if (method->batch_flag != NULL && *method->batch_flag != 0) 2225 return 0; 2226 return 1; 2227 } 2228 2229 static Authmethod * 2230 authmethod_lookup(const char *name) 2231 { 2232 Authmethod *method = NULL; 2233 if (name != NULL) 2234 for (method = authmethods; method->name != NULL; method++) 2235 if (strcmp(name, method->name) == 0) 2236 return method; 2237 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2238 return NULL; 2239 } 2240 2241 /* XXX internal state */ 2242 static Authmethod *current = NULL; 2243 static char *supported = NULL; 2244 static char *preferred = NULL; 2245 2246 /* 2247 * Given the authentication method list sent by the server, return the 2248 * next method we should try. If the server initially sends a nil list, 2249 * use a built-in default list. 2250 */ 2251 static Authmethod * 2252 authmethod_get(char *authlist) 2253 { 2254 char *name = NULL; 2255 u_int next; 2256 2257 /* Use a suitable default if we're passed a nil list. */ 2258 if (authlist == NULL || strlen(authlist) == 0) 2259 authlist = options.preferred_authentications; 2260 2261 if (supported == NULL || strcmp(authlist, supported) != 0) { 2262 debug3("start over, passed a different list %s", authlist); 2263 free(supported); 2264 supported = xstrdup(authlist); 2265 preferred = options.preferred_authentications; 2266 debug3("preferred %s", preferred); 2267 current = NULL; 2268 } else if (current != NULL && authmethod_is_enabled(current)) 2269 return current; 2270 2271 for (;;) { 2272 if ((name = match_list(preferred, supported, &next)) == NULL) { 2273 debug("No more authentication methods to try."); 2274 current = NULL; 2275 return NULL; 2276 } 2277 preferred += next; 2278 debug3("authmethod_lookup %s", name); 2279 debug3("remaining preferred: %s", preferred); 2280 if ((current = authmethod_lookup(name)) != NULL && 2281 authmethod_is_enabled(current)) { 2282 debug3("authmethod_is_enabled %s", name); 2283 debug("Next authentication method: %s", name); 2284 free(name); 2285 return current; 2286 } 2287 free(name); 2288 } 2289 } 2290 2291 static char * 2292 authmethods_get(void) 2293 { 2294 Authmethod *method = NULL; 2295 struct sshbuf *b; 2296 char *list; 2297 int r; 2298 2299 if ((b = sshbuf_new()) == NULL) 2300 fatal_f("sshbuf_new failed"); 2301 for (method = authmethods; method->name != NULL; method++) { 2302 if (authmethod_is_enabled(method)) { 2303 if ((r = sshbuf_putf(b, "%s%s", 2304 sshbuf_len(b) ? "," : "", method->name)) != 0) 2305 fatal_fr(r, "buffer error"); 2306 } 2307 } 2308 if ((list = sshbuf_dup_string(b)) == NULL) 2309 fatal_f("sshbuf_dup_string failed"); 2310 sshbuf_free(b); 2311 return list; 2312 } 2313