sshconnect2.c revision 1.1.1.29
1 /* $OpenBSD: sshconnect2.c,v 1.361 2022/09/17 10:33:18 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <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 static char *xxx_host; 88 static struct sockaddr *xxx_hostaddr; 89 static const struct ssh_conn_info *xxx_conn_info; 90 91 static int 92 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 93 { 94 int r; 95 96 if ((r = sshkey_check_rsa_length(hostkey, 97 options.required_rsa_size)) != 0) 98 fatal_r(r, "Bad server host key"); 99 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 100 xxx_conn_info) == -1) 101 fatal("Host key verification failed."); 102 return 0; 103 } 104 105 /* Returns the first item from a comma-separated algorithm list */ 106 static char * 107 first_alg(const char *algs) 108 { 109 char *ret, *cp; 110 111 ret = xstrdup(algs); 112 if ((cp = strchr(ret, ',')) != NULL) 113 *cp = '\0'; 114 return ret; 115 } 116 117 static char * 118 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 119 const struct ssh_conn_info *cinfo) 120 { 121 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 122 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 123 size_t maxlen; 124 struct hostkeys *hostkeys = NULL; 125 int ktype; 126 u_int i; 127 128 /* Find all hostkeys for this hostname */ 129 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 130 hostkeys = init_hostkeys(); 131 for (i = 0; i < options.num_user_hostfiles; i++) 132 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 133 for (i = 0; i < options.num_system_hostfiles; i++) { 134 load_hostkeys(hostkeys, hostname, 135 options.system_hostfiles[i], 0); 136 } 137 if (options.known_hosts_command != NULL) { 138 load_hostkeys_command(hostkeys, options.known_hosts_command, 139 "ORDER", cinfo, NULL, host); 140 } 141 /* 142 * If a plain public key exists that matches the type of the best 143 * preference HostkeyAlgorithms, then use the whole list as is. 144 * Note that we ignore whether the best preference algorithm is a 145 * certificate type, as sshconnect.c will downgrade certs to 146 * plain keys if necessary. 147 */ 148 best = first_alg(options.hostkeyalgorithms); 149 if (lookup_key_in_hostkeys_by_type(hostkeys, 150 sshkey_type_plain(sshkey_type_from_name(best)), 151 sshkey_ecdsa_nid_from_name(best), NULL)) { 152 debug3_f("have matching best-preference key type %s, " 153 "using HostkeyAlgorithms verbatim", best); 154 ret = xstrdup(options.hostkeyalgorithms); 155 goto out; 156 } 157 158 /* 159 * Otherwise, prefer the host key algorithms that match known keys 160 * while keeping the ordering of HostkeyAlgorithms as much as possible. 161 */ 162 oavail = avail = xstrdup(options.hostkeyalgorithms); 163 maxlen = strlen(avail) + 1; 164 first = xmalloc(maxlen); 165 last = xmalloc(maxlen); 166 *first = *last = '\0'; 167 168 #define ALG_APPEND(to, from) \ 169 do { \ 170 if (*to != '\0') \ 171 strlcat(to, ",", maxlen); \ 172 strlcat(to, from, maxlen); \ 173 } while (0) 174 175 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 176 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 177 fatal_f("unknown alg %s", alg); 178 /* 179 * If we have a @cert-authority marker in known_hosts then 180 * prefer all certificate algorithms. 181 */ 182 if (sshkey_type_is_cert(ktype) && 183 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 184 ALG_APPEND(first, alg); 185 continue; 186 } 187 /* If the key appears in known_hosts then prefer it */ 188 if (lookup_key_in_hostkeys_by_type(hostkeys, 189 sshkey_type_plain(ktype), 190 sshkey_ecdsa_nid_from_name(alg), NULL)) { 191 ALG_APPEND(first, alg); 192 continue; 193 } 194 /* Otherwise, put it last */ 195 ALG_APPEND(last, alg); 196 } 197 #undef ALG_APPEND 198 xasprintf(&ret, "%s%s%s", first, 199 (*first == '\0' || *last == '\0') ? "" : ",", last); 200 if (*first != '\0') 201 debug3_f("prefer hostkeyalgs: %s", first); 202 else 203 debug3_f("no algorithms matched; accept original"); 204 out: 205 free(best); 206 free(first); 207 free(last); 208 free(hostname); 209 free(oavail); 210 free_hostkeys(hostkeys); 211 212 return ret; 213 } 214 215 void 216 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 217 const struct ssh_conn_info *cinfo) 218 { 219 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 220 char *s, *all_key; 221 char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; 222 int r, use_known_hosts_order = 0; 223 224 xxx_host = host; 225 xxx_hostaddr = hostaddr; 226 xxx_conn_info = cinfo; 227 228 /* 229 * If the user has not specified HostkeyAlgorithms, or has only 230 * appended or removed algorithms from that list then prefer algorithms 231 * that are in the list that are supported by known_hosts keys. 232 */ 233 if (options.hostkeyalgorithms == NULL || 234 options.hostkeyalgorithms[0] == '-' || 235 options.hostkeyalgorithms[0] == '+') 236 use_known_hosts_order = 1; 237 238 /* Expand or fill in HostkeyAlgorithms */ 239 all_key = sshkey_alg_list(0, 0, 1, ','); 240 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 241 kex_default_pk_alg(), all_key)) != 0) 242 fatal_fr(r, "kex_assemble_namelist"); 243 free(all_key); 244 245 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 246 fatal_f("kex_names_cat"); 247 myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, s); 248 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 249 myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc = 250 compat_cipher_proposal(ssh, options.ciphers); 251 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 252 myproposal[PROPOSAL_COMP_ALGS_STOC] = 253 (char *)compression_alg_list(options.compression); 254 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 255 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 256 if (use_known_hosts_order) { 257 /* Query known_hosts and prefer algorithms that appear there */ 258 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 259 compat_pkalg_proposal(ssh, 260 order_hostkeyalgs(host, hostaddr, port, cinfo)); 261 } else { 262 /* Use specified HostkeyAlgorithms exactly */ 263 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 264 compat_pkalg_proposal(ssh, options.hostkeyalgorithms); 265 } 266 267 if (options.rekey_limit || options.rekey_interval) 268 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 269 options.rekey_interval); 270 271 /* start key exchange */ 272 if ((r = kex_setup(ssh, myproposal)) != 0) 273 fatal_r(r, "kex_setup"); 274 #ifdef WITH_OPENSSL 275 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 276 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 277 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 278 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 279 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 280 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 281 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 282 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 283 #endif 284 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 285 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 286 ssh->kex->verify_host_key=&verify_host_key_callback; 287 288 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 289 290 /* remove ext-info from the KEX proposals for rekeying */ 291 myproposal[PROPOSAL_KEX_ALGS] = 292 compat_kex_proposal(ssh, options.kex_algorithms); 293 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 294 fatal_r(r, "kex_prop2buf"); 295 296 #ifdef DEBUG_KEXDH 297 /* send 1st encrypted/maced/compressed message */ 298 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 299 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 300 (r = sshpkt_send(ssh)) != 0 || 301 (r = ssh_packet_write_wait(ssh)) != 0) 302 fatal_fr(r, "send packet"); 303 #endif 304 /* Free only parts of proposal that were dynamically allocated here. */ 305 free(prop_kex); 306 free(prop_enc); 307 free(prop_hostkey); 308 } 309 310 /* 311 * Authenticate user 312 */ 313 314 typedef struct cauthctxt Authctxt; 315 typedef struct cauthmethod Authmethod; 316 typedef struct identity Identity; 317 typedef struct idlist Idlist; 318 319 struct identity { 320 TAILQ_ENTRY(identity) next; 321 int agent_fd; /* >=0 if agent supports key */ 322 struct sshkey *key; /* public/private key */ 323 char *filename; /* comment for agent-only keys */ 324 int tried; 325 int isprivate; /* key points to the private key */ 326 int userprovided; 327 }; 328 TAILQ_HEAD(idlist, identity); 329 330 struct cauthctxt { 331 const char *server_user; 332 const char *local_user; 333 const char *host; 334 const char *service; 335 struct cauthmethod *method; 336 sig_atomic_t success; 337 char *authlist; 338 #ifdef GSSAPI 339 /* gssapi */ 340 gss_OID_set gss_supported_mechs; 341 u_int mech_tried; 342 #endif 343 /* pubkey */ 344 struct idlist keys; 345 int agent_fd; 346 /* hostbased */ 347 Sensitive *sensitive; 348 char *oktypes, *ktypes; 349 const char *active_ktype; 350 /* kbd-interactive */ 351 int info_req_seen; 352 int attempt_kbdint; 353 /* password */ 354 int attempt_passwd; 355 /* generic */ 356 void *methoddata; 357 }; 358 359 struct cauthmethod { 360 char *name; /* string to compare against server's list */ 361 int (*userauth)(struct ssh *ssh); 362 void (*cleanup)(struct ssh *ssh); 363 int *enabled; /* flag in option struct that enables method */ 364 int *batch_flag; /* flag in option struct that disables method */ 365 }; 366 367 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 368 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 369 static int input_userauth_success(int, u_int32_t, struct ssh *); 370 static int input_userauth_failure(int, u_int32_t, struct ssh *); 371 static int input_userauth_banner(int, u_int32_t, struct ssh *); 372 static int input_userauth_error(int, u_int32_t, struct ssh *); 373 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 374 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 375 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 376 377 static int userauth_none(struct ssh *); 378 static int userauth_pubkey(struct ssh *); 379 static int userauth_passwd(struct ssh *); 380 static int userauth_kbdint(struct ssh *); 381 static int userauth_hostbased(struct ssh *); 382 383 #ifdef GSSAPI 384 static int userauth_gssapi(struct ssh *); 385 static void userauth_gssapi_cleanup(struct ssh *); 386 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 387 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 388 static int input_gssapi_error(int, u_int32_t, struct ssh *); 389 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 390 #endif 391 392 void userauth(struct ssh *, char *); 393 394 static void pubkey_cleanup(struct ssh *); 395 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 396 static void pubkey_prepare(struct ssh *, Authctxt *); 397 static void pubkey_reset(Authctxt *); 398 static struct sshkey *load_identity_file(Identity *); 399 400 static Authmethod *authmethod_get(char *authlist); 401 static Authmethod *authmethod_lookup(const char *name); 402 static char *authmethods_get(void); 403 404 Authmethod authmethods[] = { 405 #ifdef GSSAPI 406 {"gssapi-with-mic", 407 userauth_gssapi, 408 userauth_gssapi_cleanup, 409 &options.gss_authentication, 410 NULL}, 411 #endif 412 {"hostbased", 413 userauth_hostbased, 414 NULL, 415 &options.hostbased_authentication, 416 NULL}, 417 {"publickey", 418 userauth_pubkey, 419 NULL, 420 &options.pubkey_authentication, 421 NULL}, 422 {"keyboard-interactive", 423 userauth_kbdint, 424 NULL, 425 &options.kbd_interactive_authentication, 426 &options.batch_mode}, 427 {"password", 428 userauth_passwd, 429 NULL, 430 &options.password_authentication, 431 &options.batch_mode}, 432 {"none", 433 userauth_none, 434 NULL, 435 NULL, 436 NULL}, 437 {NULL, NULL, NULL, NULL, NULL} 438 }; 439 440 void 441 ssh_userauth2(struct ssh *ssh, const char *local_user, 442 const char *server_user, char *host, Sensitive *sensitive) 443 { 444 Authctxt authctxt; 445 int r; 446 447 if (options.preferred_authentications == NULL) 448 options.preferred_authentications = authmethods_get(); 449 450 /* setup authentication context */ 451 memset(&authctxt, 0, sizeof(authctxt)); 452 authctxt.server_user = server_user; 453 authctxt.local_user = local_user; 454 authctxt.host = host; 455 authctxt.service = "ssh-connection"; /* service name */ 456 authctxt.success = 0; 457 authctxt.method = authmethod_lookup("none"); 458 authctxt.authlist = NULL; 459 authctxt.methoddata = NULL; 460 authctxt.sensitive = sensitive; 461 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 462 authctxt.info_req_seen = 0; 463 authctxt.attempt_kbdint = 0; 464 authctxt.attempt_passwd = 0; 465 #if GSSAPI 466 authctxt.gss_supported_mechs = NULL; 467 authctxt.mech_tried = 0; 468 #endif 469 authctxt.agent_fd = -1; 470 pubkey_prepare(ssh, &authctxt); 471 if (authctxt.method == NULL) { 472 fatal_f("internal error: cannot send userauth none request"); 473 } 474 475 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 476 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 477 (r = sshpkt_send(ssh)) != 0) 478 fatal_fr(r, "send packet"); 479 480 ssh->authctxt = &authctxt; 481 ssh_dispatch_init(ssh, &input_userauth_error); 482 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 483 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 484 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 485 pubkey_cleanup(ssh); 486 ssh->authctxt = NULL; 487 488 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 489 490 if (!authctxt.success) 491 fatal("Authentication failed."); 492 if (ssh_packet_connection_is_on_socket(ssh)) { 493 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 494 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 495 authctxt.method->name); 496 } else { 497 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 498 authctxt.method->name); 499 } 500 } 501 502 /* ARGSUSED */ 503 static int 504 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 505 { 506 int r; 507 508 if (ssh_packet_remaining(ssh) > 0) { 509 char *reply; 510 511 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 512 goto out; 513 debug2("service_accept: %s", reply); 514 free(reply); 515 } else { 516 debug2("buggy server: service_accept w/o service"); 517 } 518 if ((r = sshpkt_get_end(ssh)) != 0) 519 goto out; 520 debug("SSH2_MSG_SERVICE_ACCEPT received"); 521 522 /* initial userauth request */ 523 userauth_none(ssh); 524 525 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 526 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 527 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 528 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 529 r = 0; 530 out: 531 return r; 532 } 533 534 /* ARGSUSED */ 535 static int 536 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 537 { 538 return kex_input_ext_info(type, seqnr, ssh); 539 } 540 541 void 542 userauth(struct ssh *ssh, char *authlist) 543 { 544 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 545 546 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 547 authctxt->method->cleanup(ssh); 548 549 free(authctxt->methoddata); 550 authctxt->methoddata = NULL; 551 if (authlist == NULL) { 552 authlist = authctxt->authlist; 553 } else { 554 free(authctxt->authlist); 555 authctxt->authlist = authlist; 556 } 557 for (;;) { 558 Authmethod *method = authmethod_get(authlist); 559 if (method == NULL) 560 fatal("%s@%s: Permission denied (%s).", 561 authctxt->server_user, authctxt->host, authlist); 562 authctxt->method = method; 563 564 /* reset the per method handler */ 565 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 566 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 567 568 /* and try new method */ 569 if (method->userauth(ssh) != 0) { 570 debug2("we sent a %s packet, wait for reply", method->name); 571 break; 572 } else { 573 debug2("we did not send a packet, disable method"); 574 method->enabled = NULL; 575 } 576 } 577 } 578 579 /* ARGSUSED */ 580 static int 581 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 582 { 583 fatal_f("bad message during authentication: type %d", type); 584 return 0; 585 } 586 587 /* ARGSUSED */ 588 static int 589 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 590 { 591 char *msg = NULL; 592 size_t len; 593 int r; 594 595 debug3_f("entering"); 596 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 597 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 598 goto out; 599 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 600 fmprintf(stderr, "%s", msg); 601 r = 0; 602 out: 603 free(msg); 604 return r; 605 } 606 607 /* ARGSUSED */ 608 static int 609 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 610 { 611 Authctxt *authctxt = ssh->authctxt; 612 613 if (authctxt == NULL) 614 fatal_f("no authentication context"); 615 free(authctxt->authlist); 616 authctxt->authlist = NULL; 617 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 618 authctxt->method->cleanup(ssh); 619 free(authctxt->methoddata); 620 authctxt->methoddata = NULL; 621 authctxt->success = 1; /* break out */ 622 return 0; 623 } 624 625 #if 0 626 static int 627 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 628 { 629 Authctxt *authctxt = ssh->authctxt; 630 631 if (authctxt == NULL) 632 fatal_f("no authentication context"); 633 634 fatal("Unexpected authentication success during %s.", 635 authctxt->method->name); 636 return 0; 637 } 638 #endif 639 640 /* ARGSUSED */ 641 static int 642 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 643 { 644 Authctxt *authctxt = ssh->authctxt; 645 char *authlist = NULL; 646 u_char partial; 647 648 if (authctxt == NULL) 649 fatal("input_userauth_failure: no authentication context"); 650 651 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 652 sshpkt_get_u8(ssh, &partial) != 0 || 653 sshpkt_get_end(ssh) != 0) 654 goto out; 655 656 if (partial != 0) { 657 verbose("Authenticated using \"%s\" with partial success.", 658 authctxt->method->name); 659 /* reset state */ 660 pubkey_reset(authctxt); 661 } 662 debug("Authentications that can continue: %s", authlist); 663 664 userauth(ssh, authlist); 665 authlist = NULL; 666 out: 667 free(authlist); 668 return 0; 669 } 670 671 /* 672 * Format an identity for logging including filename, key type, fingerprint 673 * and location (agent, etc.). Caller must free. 674 */ 675 static char * 676 format_identity(Identity *id) 677 { 678 char *fp = NULL, *ret = NULL; 679 const char *note = ""; 680 681 if (id->key != NULL) { 682 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 683 SSH_FP_DEFAULT); 684 } 685 if (id->key) { 686 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 687 note = " token"; 688 else if (sshkey_is_sk(id->key)) 689 note = " authenticator"; 690 } 691 xasprintf(&ret, "%s %s%s%s%s%s%s", 692 id->filename, 693 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 694 fp ? fp : "", 695 id->userprovided ? " explicit" : "", note, 696 id->agent_fd != -1 ? " agent" : ""); 697 free(fp); 698 return ret; 699 } 700 701 /* ARGSUSED */ 702 static int 703 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 704 { 705 Authctxt *authctxt = ssh->authctxt; 706 struct sshkey *key = NULL; 707 Identity *id = NULL; 708 int pktype, found = 0, sent = 0; 709 size_t blen; 710 char *pkalg = NULL, *fp = NULL, *ident = NULL; 711 u_char *pkblob = NULL; 712 int r; 713 714 if (authctxt == NULL) 715 fatal("input_userauth_pk_ok: no authentication context"); 716 717 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 718 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 719 (r = sshpkt_get_end(ssh)) != 0) 720 goto done; 721 722 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 723 debug_f("server sent unknown pkalg %s", pkalg); 724 goto done; 725 } 726 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 727 debug_r(r, "no key from blob. pkalg %s", pkalg); 728 goto done; 729 } 730 if (key->type != pktype) { 731 error("input_userauth_pk_ok: type mismatch " 732 "for decoded key (received %d, expected %d)", 733 key->type, pktype); 734 goto done; 735 } 736 737 /* 738 * search keys in the reverse order, because last candidate has been 739 * moved to the end of the queue. this also avoids confusion by 740 * duplicate keys 741 */ 742 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 743 if (sshkey_equal(key, id->key)) { 744 found = 1; 745 break; 746 } 747 } 748 if (!found || id == NULL) { 749 fp = sshkey_fingerprint(key, options.fingerprint_hash, 750 SSH_FP_DEFAULT); 751 error_f("server replied with unknown key: %s %s", 752 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 753 goto done; 754 } 755 ident = format_identity(id); 756 debug("Server accepts key: %s", ident); 757 sent = sign_and_send_pubkey(ssh, id); 758 r = 0; 759 done: 760 sshkey_free(key); 761 free(ident); 762 free(fp); 763 free(pkalg); 764 free(pkblob); 765 766 /* try another method if we did not send a packet */ 767 if (r == 0 && sent == 0) 768 userauth(ssh, NULL); 769 return r; 770 } 771 772 #ifdef GSSAPI 773 static int 774 userauth_gssapi(struct ssh *ssh) 775 { 776 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 777 Gssctxt *gssctxt = NULL; 778 OM_uint32 min; 779 int r, ok = 0; 780 gss_OID mech = NULL; 781 782 /* Try one GSSAPI method at a time, rather than sending them all at 783 * once. */ 784 785 if (authctxt->gss_supported_mechs == NULL) 786 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 787 788 /* Check to see whether the mechanism is usable before we offer it */ 789 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 790 !ok) { 791 mech = &authctxt->gss_supported_mechs-> 792 elements[authctxt->mech_tried]; 793 /* My DER encoding requires length<128 */ 794 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 795 mech, authctxt->host)) { 796 ok = 1; /* Mechanism works */ 797 } else { 798 authctxt->mech_tried++; 799 } 800 } 801 802 if (!ok || mech == NULL) 803 return 0; 804 805 authctxt->methoddata=(void *)gssctxt; 806 807 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 808 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 809 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 810 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 811 (r = sshpkt_put_u32(ssh, 1)) != 0 || 812 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 813 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 814 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 815 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 816 (r = sshpkt_send(ssh)) != 0) 817 fatal_fr(r, "send packet"); 818 819 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 820 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 821 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 822 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 823 824 authctxt->mech_tried++; /* Move along to next candidate */ 825 826 return 1; 827 } 828 829 static void 830 userauth_gssapi_cleanup(struct ssh *ssh) 831 { 832 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 833 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 834 835 ssh_gssapi_delete_ctx(&gssctxt); 836 authctxt->methoddata = NULL; 837 838 free(authctxt->gss_supported_mechs); 839 authctxt->gss_supported_mechs = NULL; 840 } 841 842 static OM_uint32 843 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 844 { 845 Authctxt *authctxt = ssh->authctxt; 846 Gssctxt *gssctxt = authctxt->methoddata; 847 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 848 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 849 gss_buffer_desc gssbuf; 850 OM_uint32 status, ms, flags; 851 int r; 852 853 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 854 recv_tok, &send_tok, &flags); 855 856 if (send_tok.length > 0) { 857 u_char type = GSS_ERROR(status) ? 858 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 859 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 860 861 if ((r = sshpkt_start(ssh, type)) != 0 || 862 (r = sshpkt_put_string(ssh, send_tok.value, 863 send_tok.length)) != 0 || 864 (r = sshpkt_send(ssh)) != 0) 865 fatal_fr(r, "send %u packet", type); 866 867 gss_release_buffer(&ms, &send_tok); 868 } 869 870 if (status == GSS_S_COMPLETE) { 871 /* send either complete or MIC, depending on mechanism */ 872 if (!(flags & GSS_C_INTEG_FLAG)) { 873 if ((r = sshpkt_start(ssh, 874 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 875 (r = sshpkt_send(ssh)) != 0) 876 fatal_fr(r, "send completion"); 877 } else { 878 struct sshbuf *b; 879 880 if ((b = sshbuf_new()) == NULL) 881 fatal_f("sshbuf_new failed"); 882 ssh_gssapi_buildmic(b, authctxt->server_user, 883 authctxt->service, "gssapi-with-mic", 884 ssh->kex->session_id); 885 886 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 887 fatal_f("sshbuf_mutable_ptr failed"); 888 gssbuf.length = sshbuf_len(b); 889 890 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 891 892 if (!GSS_ERROR(status)) { 893 if ((r = sshpkt_start(ssh, 894 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 895 (r = sshpkt_put_string(ssh, mic.value, 896 mic.length)) != 0 || 897 (r = sshpkt_send(ssh)) != 0) 898 fatal_fr(r, "send MIC"); 899 } 900 901 sshbuf_free(b); 902 gss_release_buffer(&ms, &mic); 903 } 904 } 905 906 return status; 907 } 908 909 /* ARGSUSED */ 910 static int 911 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 912 { 913 Authctxt *authctxt = ssh->authctxt; 914 Gssctxt *gssctxt; 915 size_t oidlen; 916 u_char *oidv = NULL; 917 int r; 918 919 if (authctxt == NULL) 920 fatal("input_gssapi_response: no authentication context"); 921 gssctxt = authctxt->methoddata; 922 923 /* Setup our OID */ 924 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 925 goto done; 926 927 if (oidlen <= 2 || 928 oidv[0] != SSH_GSS_OIDTYPE || 929 oidv[1] != oidlen - 2) { 930 debug("Badly encoded mechanism OID received"); 931 userauth(ssh, NULL); 932 goto ok; 933 } 934 935 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 936 fatal("Server returned different OID than expected"); 937 938 if ((r = sshpkt_get_end(ssh)) != 0) 939 goto done; 940 941 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 942 /* Start again with next method on list */ 943 debug("Trying to start again"); 944 userauth(ssh, NULL); 945 goto ok; 946 } 947 ok: 948 r = 0; 949 done: 950 free(oidv); 951 return r; 952 } 953 954 /* ARGSUSED */ 955 static int 956 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 957 { 958 Authctxt *authctxt = ssh->authctxt; 959 gss_buffer_desc recv_tok; 960 u_char *p = NULL; 961 size_t len; 962 OM_uint32 status; 963 int r; 964 965 if (authctxt == NULL) 966 fatal("input_gssapi_response: no authentication context"); 967 968 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 969 (r = sshpkt_get_end(ssh)) != 0) 970 goto out; 971 972 recv_tok.value = p; 973 recv_tok.length = len; 974 status = process_gssapi_token(ssh, &recv_tok); 975 976 /* Start again with the next method in the list */ 977 if (GSS_ERROR(status)) { 978 userauth(ssh, NULL); 979 /* ok */ 980 } 981 r = 0; 982 out: 983 free(p); 984 return r; 985 } 986 987 /* ARGSUSED */ 988 static int 989 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 990 { 991 Authctxt *authctxt = ssh->authctxt; 992 Gssctxt *gssctxt; 993 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 994 gss_buffer_desc recv_tok; 995 OM_uint32 ms; 996 u_char *p = NULL; 997 size_t len; 998 int r; 999 1000 if (authctxt == NULL) 1001 fatal("input_gssapi_response: no authentication context"); 1002 gssctxt = authctxt->methoddata; 1003 1004 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1005 (r = sshpkt_get_end(ssh)) != 0) { 1006 free(p); 1007 return r; 1008 } 1009 1010 /* Stick it into GSSAPI and see what it says */ 1011 recv_tok.value = p; 1012 recv_tok.length = len; 1013 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1014 &recv_tok, &send_tok, NULL); 1015 free(p); 1016 gss_release_buffer(&ms, &send_tok); 1017 1018 /* Server will be returning a failed packet after this one */ 1019 return 0; 1020 } 1021 1022 /* ARGSUSED */ 1023 static int 1024 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1025 { 1026 char *msg = NULL; 1027 char *lang = NULL; 1028 int r; 1029 1030 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1031 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1032 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1033 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1034 goto out; 1035 r = sshpkt_get_end(ssh); 1036 debug("Server GSSAPI Error:\n%s", msg); 1037 out: 1038 free(msg); 1039 free(lang); 1040 return r; 1041 } 1042 #endif /* GSSAPI */ 1043 1044 static int 1045 userauth_none(struct ssh *ssh) 1046 { 1047 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1048 int r; 1049 1050 /* initial userauth request */ 1051 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1052 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1053 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1054 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1055 (r = sshpkt_send(ssh)) != 0) 1056 fatal_fr(r, "send packet"); 1057 return 1; 1058 } 1059 1060 static int 1061 userauth_passwd(struct ssh *ssh) 1062 { 1063 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1064 char *password, *prompt = NULL; 1065 const char *host = options.host_key_alias ? options.host_key_alias : 1066 authctxt->host; 1067 int r; 1068 1069 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1070 return 0; 1071 1072 if (authctxt->attempt_passwd != 1) 1073 error("Permission denied, please try again."); 1074 1075 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1076 password = read_passphrase(prompt, 0); 1077 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1078 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1079 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1080 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1081 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1082 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1083 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1084 (r = sshpkt_send(ssh)) != 0) 1085 fatal_fr(r, "send packet"); 1086 1087 free(prompt); 1088 if (password != NULL) 1089 freezero(password, strlen(password)); 1090 1091 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1092 &input_userauth_passwd_changereq); 1093 1094 return 1; 1095 } 1096 1097 /* 1098 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1099 */ 1100 /* ARGSUSED */ 1101 static int 1102 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1103 { 1104 Authctxt *authctxt = ssh->authctxt; 1105 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1106 char prompt[256]; 1107 const char *host; 1108 int r; 1109 1110 debug2("input_userauth_passwd_changereq"); 1111 1112 if (authctxt == NULL) 1113 fatal("input_userauth_passwd_changereq: " 1114 "no authentication context"); 1115 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1116 1117 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1118 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1119 goto out; 1120 if (strlen(info) > 0) 1121 logit("%s", info); 1122 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1123 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1124 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1125 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1126 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1127 goto out; 1128 1129 snprintf(prompt, sizeof(prompt), 1130 "Enter %.30s@%.128s's old password: ", 1131 authctxt->server_user, host); 1132 password = read_passphrase(prompt, 0); 1133 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1134 goto out; 1135 1136 freezero(password, strlen(password)); 1137 password = NULL; 1138 while (password == NULL) { 1139 snprintf(prompt, sizeof(prompt), 1140 "Enter %.30s@%.128s's new password: ", 1141 authctxt->server_user, host); 1142 password = read_passphrase(prompt, RP_ALLOW_EOF); 1143 if (password == NULL) { 1144 /* bail out */ 1145 r = 0; 1146 goto out; 1147 } 1148 snprintf(prompt, sizeof(prompt), 1149 "Retype %.30s@%.128s's new password: ", 1150 authctxt->server_user, host); 1151 retype = read_passphrase(prompt, 0); 1152 if (strcmp(password, retype) != 0) { 1153 freezero(password, strlen(password)); 1154 logit("Mismatch; try again, EOF to quit."); 1155 password = NULL; 1156 } 1157 freezero(retype, strlen(retype)); 1158 } 1159 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1160 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1161 (r = sshpkt_send(ssh)) != 0) 1162 goto out; 1163 1164 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1165 &input_userauth_passwd_changereq); 1166 r = 0; 1167 out: 1168 if (password) 1169 freezero(password, strlen(password)); 1170 free(info); 1171 free(lang); 1172 return r; 1173 } 1174 1175 /* 1176 * Select an algorithm for publickey signatures. 1177 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1178 * 1179 * Call with ssh==NULL to ignore server-sig-algs extension list and 1180 * only attempt with the key's base signature type. 1181 */ 1182 static char * 1183 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1184 { 1185 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1186 const char *server_sig_algs; 1187 1188 /* 1189 * The signature algorithm will only differ from the key algorithm 1190 * for RSA keys/certs and when the server advertises support for 1191 * newer (SHA2) algorithms. 1192 */ 1193 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1194 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1195 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1196 /* Filter base key signature alg against our configuration */ 1197 return match_list(sshkey_ssh_name(key), 1198 options.pubkey_accepted_algos, NULL); 1199 } 1200 1201 /* 1202 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1203 * fails to advertise it via SSH2_MSG_EXT_INFO. 1204 */ 1205 server_sig_algs = ssh->kex->server_sig_algs; 1206 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1207 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1208 1209 /* 1210 * For RSA keys/certs, since these might have a different sig type: 1211 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1212 * that also appears in the supported signature algorithms list from 1213 * the server. 1214 */ 1215 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1216 while ((cp = strsep(&allowed, ",")) != NULL) { 1217 if (sshkey_type_from_name(cp) != key->type) 1218 continue; 1219 tmp = match_list(sshkey_sigalg_by_name(cp), 1220 server_sig_algs, NULL); 1221 if (tmp != NULL) 1222 alg = xstrdup(cp); 1223 free(tmp); 1224 if (alg != NULL) 1225 break; 1226 } 1227 free(oallowed); 1228 return alg; 1229 } 1230 1231 static int 1232 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1233 const u_char *data, size_t datalen, u_int compat, const char *alg) 1234 { 1235 struct sshkey *sign_key = NULL, *prv = NULL; 1236 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1237 struct notifier_ctx *notifier = NULL; 1238 char *fp = NULL, *pin = NULL, *prompt = NULL; 1239 1240 *sigp = NULL; 1241 *lenp = 0; 1242 1243 /* The agent supports this key. */ 1244 if (id->key != NULL && id->agent_fd != -1) { 1245 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1246 data, datalen, alg, compat); 1247 } 1248 1249 /* 1250 * We have already loaded the private key or the private key is 1251 * stored in external hardware. 1252 */ 1253 if (id->key != NULL && 1254 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1255 sign_key = id->key; 1256 is_agent = 1; 1257 } else { 1258 /* Load the private key from the file. */ 1259 if ((prv = load_identity_file(id)) == NULL) 1260 return SSH_ERR_KEY_NOT_FOUND; 1261 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1262 error_f("private key %s contents do not match public", 1263 id->filename); 1264 r = SSH_ERR_KEY_NOT_FOUND; 1265 goto out; 1266 } 1267 sign_key = prv; 1268 } 1269 retry_pin: 1270 /* Prompt for touch for non-agent FIDO keys that request UP */ 1271 if (!is_agent && sshkey_is_sk(sign_key) && 1272 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1273 /* XXX should batch mode just skip these? */ 1274 if ((fp = sshkey_fingerprint(sign_key, 1275 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1276 fatal_f("fingerprint failed"); 1277 notifier = notify_start(options.batch_mode, 1278 "Confirm user presence for key %s %s", 1279 sshkey_type(sign_key), fp); 1280 free(fp); 1281 } 1282 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1283 alg, options.sk_provider, pin, compat)) != 0) { 1284 debug_fr(r, "sshkey_sign"); 1285 if (!retried && pin == NULL && !is_agent && 1286 sshkey_is_sk(sign_key) && 1287 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1288 notify_complete(notifier, NULL); 1289 notifier = NULL; 1290 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1291 sshkey_type(sign_key), id->filename); 1292 pin = read_passphrase(prompt, 0); 1293 retried = 1; 1294 goto retry_pin; 1295 } 1296 goto out; 1297 } 1298 1299 /* 1300 * PKCS#11 tokens may not support all signature algorithms, 1301 * so check what we get back. 1302 */ 1303 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1304 debug_fr(r, "sshkey_check_sigtype"); 1305 goto out; 1306 } 1307 /* success */ 1308 r = 0; 1309 out: 1310 free(prompt); 1311 if (pin != NULL) 1312 freezero(pin, strlen(pin)); 1313 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1314 sshkey_free(prv); 1315 return r; 1316 } 1317 1318 static int 1319 id_filename_matches(Identity *id, Identity *private_id) 1320 { 1321 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1322 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1323 size_t i, slen; 1324 1325 if (strcmp(id->filename, private_id->filename) == 0) 1326 return 1; 1327 for (i = 0; suffixes[i]; i++) { 1328 slen = strlen(suffixes[i]); 1329 if (len > slen && plen == len - slen && 1330 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1331 memcmp(id->filename, private_id->filename, plen) == 0) 1332 return 1; 1333 } 1334 return 0; 1335 } 1336 1337 static int 1338 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1339 { 1340 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1341 struct sshbuf *b = NULL; 1342 Identity *private_id, *sign_id = NULL; 1343 u_char *signature = NULL; 1344 size_t slen = 0, skip = 0; 1345 int r, fallback_sigtype, sent = 0; 1346 char *alg = NULL, *fp = NULL; 1347 const char *loc = "", *method = "publickey"; 1348 int hostbound = 0; 1349 1350 /* prefer host-bound pubkey signatures if supported by server */ 1351 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1352 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1353 hostbound = 1; 1354 method = "publickey-hostbound-v00 (at) openssh.com"; 1355 } 1356 1357 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1358 SSH_FP_DEFAULT)) == NULL) 1359 return 0; 1360 1361 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1362 1363 /* 1364 * If the key is an certificate, try to find a matching private key 1365 * and use it to complete the signature. 1366 * If no such private key exists, fall back to trying the certificate 1367 * key itself in case it has a private half already loaded. 1368 * This will try to set sign_id to the private key that will perform 1369 * the signature. 1370 */ 1371 if (sshkey_is_cert(id->key)) { 1372 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1373 if (sshkey_equal_public(id->key, private_id->key) && 1374 id->key->type != private_id->key->type) { 1375 sign_id = private_id; 1376 break; 1377 } 1378 } 1379 /* 1380 * Exact key matches are preferred, but also allow 1381 * filename matches for non-PKCS#11/agent keys that 1382 * didn't load public keys. This supports the case 1383 * of keeping just a private key file and public 1384 * certificate on disk. 1385 */ 1386 if (sign_id == NULL && 1387 !id->isprivate && id->agent_fd == -1 && 1388 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1389 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1390 if (private_id->key == NULL && 1391 id_filename_matches(id, private_id)) { 1392 sign_id = private_id; 1393 break; 1394 } 1395 } 1396 } 1397 if (sign_id != NULL) { 1398 debug2_f("using private key \"%s\"%s for " 1399 "certificate", sign_id->filename, 1400 sign_id->agent_fd != -1 ? " from agent" : ""); 1401 } else { 1402 debug_f("no separate private key for certificate " 1403 "\"%s\"", id->filename); 1404 } 1405 } 1406 1407 /* 1408 * If the above didn't select another identity to do the signing 1409 * then default to the one we started with. 1410 */ 1411 if (sign_id == NULL) 1412 sign_id = id; 1413 1414 /* assemble and sign data */ 1415 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1416 free(alg); 1417 slen = 0; 1418 signature = NULL; 1419 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1420 id->key)) == NULL) { 1421 error_f("no mutual signature supported"); 1422 goto out; 1423 } 1424 debug3_f("signing using %s %s", alg, fp); 1425 1426 sshbuf_free(b); 1427 if ((b = sshbuf_new()) == NULL) 1428 fatal_f("sshbuf_new failed"); 1429 if (ssh->compat & SSH_OLD_SESSIONID) { 1430 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1431 fatal_fr(r, "sshbuf_putb"); 1432 } else { 1433 if ((r = sshbuf_put_stringb(b, 1434 ssh->kex->session_id)) != 0) 1435 fatal_fr(r, "sshbuf_put_stringb"); 1436 } 1437 skip = sshbuf_len(b); 1438 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1439 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1440 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1441 (r = sshbuf_put_cstring(b, method)) != 0 || 1442 (r = sshbuf_put_u8(b, 1)) != 0 || 1443 (r = sshbuf_put_cstring(b, alg)) != 0 || 1444 (r = sshkey_puts(id->key, b)) != 0) { 1445 fatal_fr(r, "assemble signed data"); 1446 } 1447 if (hostbound) { 1448 if (ssh->kex->initial_hostkey == NULL) { 1449 fatal_f("internal error: initial hostkey " 1450 "not recorded"); 1451 } 1452 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1453 fatal_fr(r, "assemble %s hostkey", method); 1454 } 1455 /* generate signature */ 1456 r = identity_sign(sign_id, &signature, &slen, 1457 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1458 if (r == 0) 1459 break; 1460 else if (r == SSH_ERR_KEY_NOT_FOUND) 1461 goto out; /* soft failure */ 1462 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1463 !fallback_sigtype) { 1464 if (sign_id->agent_fd != -1) 1465 loc = "agent "; 1466 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1467 loc = "token "; 1468 logit("%skey %s %s returned incorrect signature type", 1469 loc, sshkey_type(id->key), fp); 1470 continue; 1471 } 1472 error_fr(r, "signing failed for %s \"%s\"%s", 1473 sshkey_type(sign_id->key), sign_id->filename, 1474 id->agent_fd != -1 ? " from agent" : ""); 1475 goto out; 1476 } 1477 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1478 fatal_f("no signature"); 1479 1480 /* append signature */ 1481 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1482 fatal_fr(r, "append signature"); 1483 1484 #ifdef DEBUG_PK 1485 sshbuf_dump(b, stderr); 1486 #endif 1487 /* skip session id and packet type */ 1488 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1489 fatal_fr(r, "consume"); 1490 1491 /* put remaining data from buffer into packet */ 1492 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1493 (r = sshpkt_putb(ssh, b)) != 0 || 1494 (r = sshpkt_send(ssh)) != 0) 1495 fatal_fr(r, "enqueue request"); 1496 1497 /* success */ 1498 sent = 1; 1499 1500 out: 1501 free(fp); 1502 free(alg); 1503 sshbuf_free(b); 1504 freezero(signature, slen); 1505 return sent; 1506 } 1507 1508 static int 1509 send_pubkey_test(struct ssh *ssh, Identity *id) 1510 { 1511 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1512 u_char *blob = NULL; 1513 char *alg = NULL; 1514 size_t bloblen; 1515 u_int have_sig = 0; 1516 int sent = 0, r; 1517 1518 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1519 debug_f("no mutual signature algorithm"); 1520 goto out; 1521 } 1522 1523 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1524 /* we cannot handle this key */ 1525 debug3_f("cannot handle key"); 1526 goto out; 1527 } 1528 /* register callback for USERAUTH_PK_OK message */ 1529 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1530 1531 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1532 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1533 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1534 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1535 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1536 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1537 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1538 (r = sshpkt_send(ssh)) != 0) 1539 fatal_fr(r, "send packet"); 1540 sent = 1; 1541 1542 out: 1543 free(alg); 1544 free(blob); 1545 return sent; 1546 } 1547 1548 static struct sshkey * 1549 load_identity_file(Identity *id) 1550 { 1551 struct sshkey *private = NULL; 1552 char prompt[300], *passphrase, *comment; 1553 int r, quit = 0, i; 1554 struct stat st; 1555 1556 if (stat(id->filename, &st) == -1) { 1557 do_log2(id->userprovided ? 1558 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1559 "no such identity: %s: %s", id->filename, strerror(errno)); 1560 return NULL; 1561 } 1562 snprintf(prompt, sizeof prompt, 1563 "Enter passphrase for key '%.100s': ", id->filename); 1564 for (i = 0; i <= options.number_of_password_prompts; i++) { 1565 if (i == 0) 1566 passphrase = ""; 1567 else { 1568 passphrase = read_passphrase(prompt, 0); 1569 if (*passphrase == '\0') { 1570 debug2("no passphrase given, try next key"); 1571 free(passphrase); 1572 break; 1573 } 1574 } 1575 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1576 passphrase, &private, &comment))) { 1577 case 0: 1578 break; 1579 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1580 if (options.batch_mode) { 1581 quit = 1; 1582 break; 1583 } 1584 if (i != 0) 1585 debug2("bad passphrase given, try again..."); 1586 break; 1587 case SSH_ERR_SYSTEM_ERROR: 1588 if (errno == ENOENT) { 1589 debug2_r(r, "Load key \"%s\"", id->filename); 1590 quit = 1; 1591 break; 1592 } 1593 /* FALLTHROUGH */ 1594 default: 1595 error_r(r, "Load key \"%s\"", id->filename); 1596 quit = 1; 1597 break; 1598 } 1599 if (private != NULL && sshkey_is_sk(private) && 1600 options.sk_provider == NULL) { 1601 debug("key \"%s\" is an authenticator-hosted key, " 1602 "but no provider specified", id->filename); 1603 sshkey_free(private); 1604 private = NULL; 1605 quit = 1; 1606 } 1607 if (!quit && (r = sshkey_check_rsa_length(private, 1608 options.required_rsa_size)) != 0) { 1609 debug_fr(r, "Skipping key %s", id->filename); 1610 sshkey_free(private); 1611 private = NULL; 1612 quit = 1; 1613 } 1614 if (!quit && private != NULL && id->agent_fd == -1 && 1615 !(id->key && id->isprivate)) 1616 maybe_add_key_to_agent(id->filename, private, comment, 1617 passphrase); 1618 if (i > 0) 1619 freezero(passphrase, strlen(passphrase)); 1620 free(comment); 1621 if (private != NULL || quit) 1622 break; 1623 } 1624 return private; 1625 } 1626 1627 static int 1628 key_type_allowed_by_config(struct sshkey *key) 1629 { 1630 if (match_pattern_list(sshkey_ssh_name(key), 1631 options.pubkey_accepted_algos, 0) == 1) 1632 return 1; 1633 1634 /* RSA keys/certs might be allowed by alternate signature types */ 1635 switch (key->type) { 1636 case KEY_RSA: 1637 if (match_pattern_list("rsa-sha2-512", 1638 options.pubkey_accepted_algos, 0) == 1) 1639 return 1; 1640 if (match_pattern_list("rsa-sha2-256", 1641 options.pubkey_accepted_algos, 0) == 1) 1642 return 1; 1643 break; 1644 case KEY_RSA_CERT: 1645 if (match_pattern_list("rsa-sha2-512-cert-v01 (at) openssh.com", 1646 options.pubkey_accepted_algos, 0) == 1) 1647 return 1; 1648 if (match_pattern_list("rsa-sha2-256-cert-v01 (at) openssh.com", 1649 options.pubkey_accepted_algos, 0) == 1) 1650 return 1; 1651 break; 1652 } 1653 return 0; 1654 } 1655 1656 /* obtain a list of keys from the agent */ 1657 static int 1658 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1659 struct ssh_identitylist **idlistp) 1660 { 1661 int r, agent_fd; 1662 struct ssh_identitylist *idlist; 1663 1664 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1665 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1666 debug_fr(r, "ssh_get_authentication_socket"); 1667 return r; 1668 } 1669 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1670 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1671 debug_f("bound agent to hostkey"); 1672 else 1673 debug2_fr(r, "ssh_agent_bind_hostkey"); 1674 1675 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1676 debug_fr(r, "ssh_fetch_identitylist"); 1677 close(agent_fd); 1678 return r; 1679 } 1680 /* success */ 1681 *agent_fdp = agent_fd; 1682 *idlistp = idlist; 1683 debug_f("agent returned %zu keys", idlist->nkeys); 1684 return 0; 1685 } 1686 1687 /* 1688 * try keys in the following order: 1689 * 1. certificates listed in the config file 1690 * 2. other input certificates 1691 * 3. agent keys that are found in the config file 1692 * 4. other agent keys 1693 * 5. keys that are only listed in the config file 1694 */ 1695 static void 1696 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1697 { 1698 struct identity *id, *id2, *tmp; 1699 struct idlist agent, files, *preferred; 1700 struct sshkey *key; 1701 int agent_fd = -1, i, r, found; 1702 size_t j; 1703 struct ssh_identitylist *idlist; 1704 char *ident; 1705 1706 TAILQ_INIT(&agent); /* keys from the agent */ 1707 TAILQ_INIT(&files); /* keys from the config file */ 1708 preferred = &authctxt->keys; 1709 TAILQ_INIT(preferred); /* preferred order of keys */ 1710 1711 /* list of keys stored in the filesystem and PKCS#11 */ 1712 for (i = 0; i < options.num_identity_files; i++) { 1713 key = options.identity_keys[i]; 1714 if (key && key->cert && 1715 key->cert->type != SSH2_CERT_TYPE_USER) { 1716 debug_f("ignoring certificate %s: not a user " 1717 "certificate", options.identity_files[i]); 1718 continue; 1719 } 1720 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1721 debug_f("ignoring authenticator-hosted key %s as no " 1722 "SecurityKeyProvider has been specified", 1723 options.identity_files[i]); 1724 continue; 1725 } 1726 options.identity_keys[i] = NULL; 1727 id = xcalloc(1, sizeof(*id)); 1728 id->agent_fd = -1; 1729 id->key = key; 1730 id->filename = xstrdup(options.identity_files[i]); 1731 id->userprovided = options.identity_file_userprovided[i]; 1732 TAILQ_INSERT_TAIL(&files, id, next); 1733 } 1734 /* list of certificates specified by user */ 1735 for (i = 0; i < options.num_certificate_files; i++) { 1736 key = options.certificates[i]; 1737 if (!sshkey_is_cert(key) || key->cert == NULL || 1738 key->cert->type != SSH2_CERT_TYPE_USER) { 1739 debug_f("ignoring certificate %s: not a user " 1740 "certificate", options.identity_files[i]); 1741 continue; 1742 } 1743 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1744 debug_f("ignoring authenticator-hosted key " 1745 "certificate %s as no " 1746 "SecurityKeyProvider has been specified", 1747 options.identity_files[i]); 1748 continue; 1749 } 1750 id = xcalloc(1, sizeof(*id)); 1751 id->agent_fd = -1; 1752 id->key = key; 1753 id->filename = xstrdup(options.certificate_files[i]); 1754 id->userprovided = options.certificate_file_userprovided[i]; 1755 TAILQ_INSERT_TAIL(preferred, id, next); 1756 } 1757 /* list of keys supported by the agent */ 1758 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1759 for (j = 0; j < idlist->nkeys; j++) { 1760 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1761 options.required_rsa_size)) != 0) { 1762 debug_fr(r, "ignoring %s agent key", 1763 sshkey_ssh_name(idlist->keys[j])); 1764 continue; 1765 } 1766 found = 0; 1767 TAILQ_FOREACH(id, &files, next) { 1768 /* 1769 * agent keys from the config file are 1770 * preferred 1771 */ 1772 if (sshkey_equal(idlist->keys[j], id->key)) { 1773 TAILQ_REMOVE(&files, id, next); 1774 TAILQ_INSERT_TAIL(preferred, id, next); 1775 id->agent_fd = agent_fd; 1776 found = 1; 1777 break; 1778 } 1779 } 1780 if (!found && !options.identities_only) { 1781 id = xcalloc(1, sizeof(*id)); 1782 /* XXX "steals" key/comment from idlist */ 1783 id->key = idlist->keys[j]; 1784 id->filename = idlist->comments[j]; 1785 idlist->keys[j] = NULL; 1786 idlist->comments[j] = NULL; 1787 id->agent_fd = agent_fd; 1788 TAILQ_INSERT_TAIL(&agent, id, next); 1789 } 1790 } 1791 ssh_free_identitylist(idlist); 1792 /* append remaining agent keys */ 1793 TAILQ_CONCAT(preferred, &agent, next); 1794 authctxt->agent_fd = agent_fd; 1795 } 1796 /* Prefer PKCS11 keys that are explicitly listed */ 1797 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1798 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1799 continue; 1800 found = 0; 1801 TAILQ_FOREACH(id2, &files, next) { 1802 if (id2->key == NULL || 1803 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1804 continue; 1805 if (sshkey_equal(id->key, id2->key)) { 1806 TAILQ_REMOVE(&files, id, next); 1807 TAILQ_INSERT_TAIL(preferred, id, next); 1808 found = 1; 1809 break; 1810 } 1811 } 1812 /* If IdentitiesOnly set and key not found then don't use it */ 1813 if (!found && options.identities_only) { 1814 TAILQ_REMOVE(&files, id, next); 1815 freezero(id, sizeof(*id)); 1816 } 1817 } 1818 /* append remaining keys from the config file */ 1819 TAILQ_CONCAT(preferred, &files, next); 1820 /* finally, filter by PubkeyAcceptedAlgorithms */ 1821 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1822 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1823 debug("Skipping %s key %s - " 1824 "corresponding algo not in PubkeyAcceptedAlgorithms", 1825 sshkey_ssh_name(id->key), id->filename); 1826 TAILQ_REMOVE(preferred, id, next); 1827 sshkey_free(id->key); 1828 free(id->filename); 1829 memset(id, 0, sizeof(*id)); 1830 continue; 1831 } 1832 } 1833 /* List the keys we plan on using */ 1834 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1835 ident = format_identity(id); 1836 debug("Will attempt key: %s", ident); 1837 free(ident); 1838 } 1839 debug2_f("done"); 1840 } 1841 1842 static void 1843 pubkey_cleanup(struct ssh *ssh) 1844 { 1845 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1846 Identity *id; 1847 1848 if (authctxt->agent_fd != -1) { 1849 ssh_close_authentication_socket(authctxt->agent_fd); 1850 authctxt->agent_fd = -1; 1851 } 1852 for (id = TAILQ_FIRST(&authctxt->keys); id; 1853 id = TAILQ_FIRST(&authctxt->keys)) { 1854 TAILQ_REMOVE(&authctxt->keys, id, next); 1855 sshkey_free(id->key); 1856 free(id->filename); 1857 free(id); 1858 } 1859 } 1860 1861 static void 1862 pubkey_reset(Authctxt *authctxt) 1863 { 1864 Identity *id; 1865 1866 TAILQ_FOREACH(id, &authctxt->keys, next) 1867 id->tried = 0; 1868 } 1869 1870 static int 1871 try_identity(struct ssh *ssh, Identity *id) 1872 { 1873 if (!id->key) 1874 return (0); 1875 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1876 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 1877 debug("Skipped %s key %s for RSA/MD5 server", 1878 sshkey_type(id->key), id->filename); 1879 return (0); 1880 } 1881 return 1; 1882 } 1883 1884 static int 1885 userauth_pubkey(struct ssh *ssh) 1886 { 1887 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1888 Identity *id; 1889 int sent = 0; 1890 char *ident; 1891 1892 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1893 if (id->tried++) 1894 return (0); 1895 /* move key to the end of the queue */ 1896 TAILQ_REMOVE(&authctxt->keys, id, next); 1897 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1898 /* 1899 * send a test message if we have the public key. for 1900 * encrypted keys we cannot do this and have to load the 1901 * private key instead 1902 */ 1903 if (id->key != NULL) { 1904 if (try_identity(ssh, id)) { 1905 ident = format_identity(id); 1906 debug("Offering public key: %s", ident); 1907 free(ident); 1908 sent = send_pubkey_test(ssh, id); 1909 } 1910 } else { 1911 debug("Trying private key: %s", id->filename); 1912 id->key = load_identity_file(id); 1913 if (id->key != NULL) { 1914 if (try_identity(ssh, id)) { 1915 id->isprivate = 1; 1916 sent = sign_and_send_pubkey(ssh, id); 1917 } 1918 sshkey_free(id->key); 1919 id->key = NULL; 1920 id->isprivate = 0; 1921 } 1922 } 1923 if (sent) 1924 return (sent); 1925 } 1926 return (0); 1927 } 1928 1929 /* 1930 * Send userauth request message specifying keyboard-interactive method. 1931 */ 1932 static int 1933 userauth_kbdint(struct ssh *ssh) 1934 { 1935 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1936 int r; 1937 1938 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1939 return 0; 1940 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1941 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1942 debug3("userauth_kbdint: disable: no info_req_seen"); 1943 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1944 return 0; 1945 } 1946 1947 debug2("userauth_kbdint"); 1948 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1949 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1950 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1951 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1952 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1953 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1954 options.kbd_interactive_devices : "")) != 0 || 1955 (r = sshpkt_send(ssh)) != 0) 1956 fatal_fr(r, "send packet"); 1957 1958 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1959 return 1; 1960 } 1961 1962 /* 1963 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1964 */ 1965 static int 1966 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1967 { 1968 Authctxt *authctxt = ssh->authctxt; 1969 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1970 char *display_prompt = NULL, *response = NULL; 1971 u_char echo = 0; 1972 u_int num_prompts, i; 1973 int r; 1974 1975 debug2_f("entering"); 1976 1977 if (authctxt == NULL) 1978 fatal_f("no authentication context"); 1979 1980 authctxt->info_req_seen = 1; 1981 1982 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1983 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1984 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1985 goto out; 1986 if (strlen(name) > 0) 1987 logit("%s", name); 1988 if (strlen(inst) > 0) 1989 logit("%s", inst); 1990 1991 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1992 goto out; 1993 /* 1994 * Begin to build info response packet based on prompts requested. 1995 * We commit to providing the correct number of responses, so if 1996 * further on we run into a problem that prevents this, we have to 1997 * be sure and clean this up and send a correct error response. 1998 */ 1999 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 2000 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 2001 goto out; 2002 2003 debug2_f("num_prompts %d", num_prompts); 2004 for (i = 0; i < num_prompts; i++) { 2005 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 2006 (r = sshpkt_get_u8(ssh, &echo)) != 0) 2007 goto out; 2008 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 2009 authctxt->server_user, options.host_key_alias ? 2010 options.host_key_alias : authctxt->host, prompt) == -1) 2011 fatal_f("asmprintf failed"); 2012 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 2013 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 2014 goto out; 2015 freezero(response, strlen(response)); 2016 free(prompt); 2017 free(display_prompt); 2018 display_prompt = response = prompt = NULL; 2019 } 2020 /* done with parsing incoming message. */ 2021 if ((r = sshpkt_get_end(ssh)) != 0 || 2022 (r = sshpkt_add_padding(ssh, 64)) != 0) 2023 goto out; 2024 r = sshpkt_send(ssh); 2025 out: 2026 if (response) 2027 freezero(response, strlen(response)); 2028 free(prompt); 2029 free(display_prompt); 2030 free(name); 2031 free(inst); 2032 free(lang); 2033 return r; 2034 } 2035 2036 static int 2037 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2038 const u_char *data, size_t datalen) 2039 { 2040 struct sshbuf *b; 2041 struct stat st; 2042 pid_t pid; 2043 int r, to[2], from[2], status; 2044 int sock = ssh_packet_get_connection_in(ssh); 2045 u_char rversion = 0, version = 2; 2046 void (*osigchld)(int); 2047 2048 *sigp = NULL; 2049 *lenp = 0; 2050 2051 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2052 error_f("not installed: %s", strerror(errno)); 2053 return -1; 2054 } 2055 if (fflush(stdout) != 0) { 2056 error_f("fflush: %s", strerror(errno)); 2057 return -1; 2058 } 2059 if (pipe(to) == -1) { 2060 error_f("pipe: %s", strerror(errno)); 2061 return -1; 2062 } 2063 if (pipe(from) == -1) { 2064 error_f("pipe: %s", strerror(errno)); 2065 return -1; 2066 } 2067 if ((pid = fork()) == -1) { 2068 error_f("fork: %s", strerror(errno)); 2069 return -1; 2070 } 2071 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2072 if (pid == 0) { 2073 close(from[0]); 2074 if (dup2(from[1], STDOUT_FILENO) == -1) 2075 fatal_f("dup2: %s", strerror(errno)); 2076 close(to[1]); 2077 if (dup2(to[0], STDIN_FILENO) == -1) 2078 fatal_f("dup2: %s", strerror(errno)); 2079 close(from[1]); 2080 close(to[0]); 2081 2082 if (dup2(sock, STDERR_FILENO + 1) == -1) 2083 fatal_f("dup2: %s", strerror(errno)); 2084 sock = STDERR_FILENO + 1; 2085 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2086 closefrom(sock + 1); 2087 2088 debug3_f("[child] pid=%ld, exec %s", 2089 (long)getpid(), _PATH_SSH_KEY_SIGN); 2090 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2091 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2092 strerror(errno)); 2093 } 2094 close(from[1]); 2095 close(to[0]); 2096 sock = STDERR_FILENO + 1; 2097 2098 if ((b = sshbuf_new()) == NULL) 2099 fatal_f("sshbuf_new failed"); 2100 /* send # of sock, data to be signed */ 2101 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2102 (r = sshbuf_put_string(b, data, datalen)) != 0) 2103 fatal_fr(r, "buffer error"); 2104 if (ssh_msg_send(to[1], version, b) == -1) 2105 fatal_f("couldn't send request"); 2106 sshbuf_reset(b); 2107 r = ssh_msg_recv(from[0], b); 2108 close(from[0]); 2109 close(to[1]); 2110 if (r < 0) { 2111 error_f("no reply"); 2112 goto fail; 2113 } 2114 2115 errno = 0; 2116 while (waitpid(pid, &status, 0) == -1) { 2117 if (errno != EINTR) { 2118 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2119 goto fail; 2120 } 2121 } 2122 if (!WIFEXITED(status)) { 2123 error_f("exited abnormally"); 2124 goto fail; 2125 } 2126 if (WEXITSTATUS(status) != 0) { 2127 error_f("exited with status %d", WEXITSTATUS(status)); 2128 goto fail; 2129 } 2130 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2131 error_fr(r, "buffer error"); 2132 goto fail; 2133 } 2134 if (rversion != version) { 2135 error_f("bad version"); 2136 goto fail; 2137 } 2138 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2139 error_fr(r, "buffer error"); 2140 fail: 2141 ssh_signal(SIGCHLD, osigchld); 2142 sshbuf_free(b); 2143 return -1; 2144 } 2145 ssh_signal(SIGCHLD, osigchld); 2146 sshbuf_free(b); 2147 2148 return 0; 2149 } 2150 2151 static int 2152 userauth_hostbased(struct ssh *ssh) 2153 { 2154 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2155 struct sshkey *private = NULL; 2156 struct sshbuf *b = NULL; 2157 u_char *sig = NULL, *keyblob = NULL; 2158 char *fp = NULL, *chost = NULL, *lname = NULL; 2159 size_t siglen = 0, keylen = 0; 2160 int i, r, success = 0; 2161 2162 if (authctxt->ktypes == NULL) { 2163 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2164 authctxt->ktypes = authctxt->oktypes; 2165 } 2166 2167 /* 2168 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2169 * trying each hostkey that matches the type in turn. 2170 */ 2171 for (;;) { 2172 if (authctxt->active_ktype == NULL) 2173 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2174 if (authctxt->active_ktype == NULL || 2175 *authctxt->active_ktype == '\0') 2176 break; 2177 debug3_f("trying key type %s", authctxt->active_ktype); 2178 2179 /* check for a useful key */ 2180 private = NULL; 2181 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2182 if (authctxt->sensitive->keys[i] == NULL || 2183 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2184 continue; 2185 if (!sshkey_match_keyname_to_sigalgs( 2186 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2187 authctxt->active_ktype)) 2188 continue; 2189 /* we take and free the key */ 2190 private = authctxt->sensitive->keys[i]; 2191 authctxt->sensitive->keys[i] = NULL; 2192 break; 2193 } 2194 /* Found one */ 2195 if (private != NULL) 2196 break; 2197 /* No more keys of this type; advance */ 2198 authctxt->active_ktype = NULL; 2199 } 2200 if (private == NULL) { 2201 free(authctxt->oktypes); 2202 authctxt->oktypes = authctxt->ktypes = NULL; 2203 authctxt->active_ktype = NULL; 2204 debug("No more client hostkeys for hostbased authentication."); 2205 goto out; 2206 } 2207 2208 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2209 SSH_FP_DEFAULT)) == NULL) { 2210 error_f("sshkey_fingerprint failed"); 2211 goto out; 2212 } 2213 debug_f("trying hostkey %s %s using sigalg %s", 2214 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2215 2216 /* figure out a name for the client host */ 2217 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2218 if (lname == NULL) { 2219 error_f("cannot get local ipaddr/name"); 2220 goto out; 2221 } 2222 2223 /* XXX sshbuf_put_stringf? */ 2224 xasprintf(&chost, "%s.", lname); 2225 debug2_f("chost %s", chost); 2226 2227 /* construct data */ 2228 if ((b = sshbuf_new()) == NULL) { 2229 error_f("sshbuf_new failed"); 2230 goto out; 2231 } 2232 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2233 error_fr(r, "sshkey_to_blob"); 2234 goto out; 2235 } 2236 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2237 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2238 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2239 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2240 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2241 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2242 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2243 (r = sshbuf_put_cstring(b, chost)) != 0 || 2244 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2245 error_fr(r, "buffer error"); 2246 goto out; 2247 } 2248 2249 #ifdef DEBUG_PK 2250 sshbuf_dump(b, stderr); 2251 #endif 2252 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2253 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2254 error("sign using hostkey %s %s failed", 2255 sshkey_ssh_name(private), fp); 2256 goto out; 2257 } 2258 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2259 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2260 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2261 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2262 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2263 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2264 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2265 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2266 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2267 (r = sshpkt_send(ssh)) != 0) { 2268 error_fr(r, "packet error"); 2269 goto out; 2270 } 2271 success = 1; 2272 2273 out: 2274 if (sig != NULL) 2275 freezero(sig, siglen); 2276 free(keyblob); 2277 free(lname); 2278 free(fp); 2279 free(chost); 2280 sshkey_free(private); 2281 sshbuf_free(b); 2282 2283 return success; 2284 } 2285 2286 /* find auth method */ 2287 2288 /* 2289 * given auth method name, if configurable options permit this method fill 2290 * in auth_ident field and return true, otherwise return false. 2291 */ 2292 static int 2293 authmethod_is_enabled(Authmethod *method) 2294 { 2295 if (method == NULL) 2296 return 0; 2297 /* return false if options indicate this method is disabled */ 2298 if (method->enabled == NULL || *method->enabled == 0) 2299 return 0; 2300 /* return false if batch mode is enabled but method needs interactive mode */ 2301 if (method->batch_flag != NULL && *method->batch_flag != 0) 2302 return 0; 2303 return 1; 2304 } 2305 2306 static Authmethod * 2307 authmethod_lookup(const char *name) 2308 { 2309 Authmethod *method = NULL; 2310 if (name != NULL) 2311 for (method = authmethods; method->name != NULL; method++) 2312 if (strcmp(name, method->name) == 0) 2313 return method; 2314 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2315 return NULL; 2316 } 2317 2318 /* XXX internal state */ 2319 static Authmethod *current = NULL; 2320 static char *supported = NULL; 2321 static char *preferred = NULL; 2322 2323 /* 2324 * Given the authentication method list sent by the server, return the 2325 * next method we should try. If the server initially sends a nil list, 2326 * use a built-in default list. 2327 */ 2328 static Authmethod * 2329 authmethod_get(char *authlist) 2330 { 2331 char *name = NULL; 2332 u_int next; 2333 2334 /* Use a suitable default if we're passed a nil list. */ 2335 if (authlist == NULL || strlen(authlist) == 0) 2336 authlist = options.preferred_authentications; 2337 2338 if (supported == NULL || strcmp(authlist, supported) != 0) { 2339 debug3("start over, passed a different list %s", authlist); 2340 free(supported); 2341 supported = xstrdup(authlist); 2342 preferred = options.preferred_authentications; 2343 debug3("preferred %s", preferred); 2344 current = NULL; 2345 } else if (current != NULL && authmethod_is_enabled(current)) 2346 return current; 2347 2348 for (;;) { 2349 if ((name = match_list(preferred, supported, &next)) == NULL) { 2350 debug("No more authentication methods to try."); 2351 current = NULL; 2352 return NULL; 2353 } 2354 preferred += next; 2355 debug3("authmethod_lookup %s", name); 2356 debug3("remaining preferred: %s", preferred); 2357 if ((current = authmethod_lookup(name)) != NULL && 2358 authmethod_is_enabled(current)) { 2359 debug3("authmethod_is_enabled %s", name); 2360 debug("Next authentication method: %s", name); 2361 free(name); 2362 return current; 2363 } 2364 free(name); 2365 } 2366 } 2367 2368 static char * 2369 authmethods_get(void) 2370 { 2371 Authmethod *method = NULL; 2372 struct sshbuf *b; 2373 char *list; 2374 int r; 2375 2376 if ((b = sshbuf_new()) == NULL) 2377 fatal_f("sshbuf_new failed"); 2378 for (method = authmethods; method->name != NULL; method++) { 2379 if (authmethod_is_enabled(method)) { 2380 if ((r = sshbuf_putf(b, "%s%s", 2381 sshbuf_len(b) ? "," : "", method->name)) != 0) 2382 fatal_fr(r, "buffer error"); 2383 } 2384 } 2385 if ((list = sshbuf_dup_string(b)) == NULL) 2386 fatal_f("sshbuf_dup_string failed"); 2387 sshbuf_free(b); 2388 return list; 2389 } 2390
Indexes created Fri Mar 06 19:51:54 UTC 2026