sshconnect2.c revision 1.1.1.27
1 /* $OpenBSD: sshconnect2.c,v 1.351 2021/07/23 05:24:02 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 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 95 xxx_conn_info) == -1) 96 fatal("Host key verification failed."); 97 return 0; 98 } 99 100 /* Returns the first item from a comma-separated algorithm list */ 101 static char * 102 first_alg(const char *algs) 103 { 104 char *ret, *cp; 105 106 ret = xstrdup(algs); 107 if ((cp = strchr(ret, ',')) != NULL) 108 *cp = '\0'; 109 return ret; 110 } 111 112 static char * 113 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 114 const struct ssh_conn_info *cinfo) 115 { 116 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 117 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 118 size_t maxlen; 119 struct hostkeys *hostkeys = NULL; 120 int ktype; 121 u_int i; 122 123 /* Find all hostkeys for this hostname */ 124 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 125 hostkeys = init_hostkeys(); 126 for (i = 0; i < options.num_user_hostfiles; i++) 127 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 128 for (i = 0; i < options.num_system_hostfiles; i++) { 129 load_hostkeys(hostkeys, hostname, 130 options.system_hostfiles[i], 0); 131 } 132 if (options.known_hosts_command != NULL) { 133 load_hostkeys_command(hostkeys, options.known_hosts_command, 134 "ORDER", cinfo, NULL, host); 135 } 136 /* 137 * If a plain public key exists that matches the type of the best 138 * preference HostkeyAlgorithms, then use the whole list as is. 139 * Note that we ignore whether the best preference algorithm is a 140 * certificate type, as sshconnect.c will downgrade certs to 141 * plain keys if necessary. 142 */ 143 best = first_alg(options.hostkeyalgorithms); 144 if (lookup_key_in_hostkeys_by_type(hostkeys, 145 sshkey_type_plain(sshkey_type_from_name(best)), 146 sshkey_ecdsa_nid_from_name(best), NULL)) { 147 debug3_f("have matching best-preference key type %s, " 148 "using HostkeyAlgorithms verbatim", best); 149 ret = xstrdup(options.hostkeyalgorithms); 150 goto out; 151 } 152 153 /* 154 * Otherwise, prefer the host key algorithms that match known keys 155 * while keeping the ordering of HostkeyAlgorithms as much as possible. 156 */ 157 oavail = avail = xstrdup(options.hostkeyalgorithms); 158 maxlen = strlen(avail) + 1; 159 first = xmalloc(maxlen); 160 last = xmalloc(maxlen); 161 *first = *last = '\0'; 162 163 #define ALG_APPEND(to, from) \ 164 do { \ 165 if (*to != '\0') \ 166 strlcat(to, ",", maxlen); \ 167 strlcat(to, from, maxlen); \ 168 } while (0) 169 170 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 171 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 172 fatal_f("unknown alg %s", alg); 173 /* 174 * If we have a @cert-authority marker in known_hosts then 175 * prefer all certificate algorithms. 176 */ 177 if (sshkey_type_is_cert(ktype) && 178 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 179 ALG_APPEND(first, alg); 180 continue; 181 } 182 /* If the key appears in known_hosts then prefer it */ 183 if (lookup_key_in_hostkeys_by_type(hostkeys, 184 sshkey_type_plain(ktype), 185 sshkey_ecdsa_nid_from_name(alg), NULL)) { 186 ALG_APPEND(first, alg); 187 continue; 188 } 189 /* Otherwise, put it last */ 190 ALG_APPEND(last, alg); 191 } 192 #undef ALG_APPEND 193 xasprintf(&ret, "%s%s%s", first, 194 (*first == '\0' || *last == '\0') ? "" : ",", last); 195 if (*first != '\0') 196 debug3_f("prefer hostkeyalgs: %s", first); 197 else 198 debug3_f("no algorithms matched; accept original"); 199 out: 200 free(best); 201 free(first); 202 free(last); 203 free(hostname); 204 free(oavail); 205 free_hostkeys(hostkeys); 206 207 return ret; 208 } 209 210 void 211 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 212 const struct ssh_conn_info *cinfo) 213 { 214 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 215 char *s, *all_key; 216 int r, use_known_hosts_order = 0; 217 218 xxx_host = host; 219 xxx_hostaddr = hostaddr; 220 xxx_conn_info = cinfo; 221 222 /* 223 * If the user has not specified HostkeyAlgorithms, or has only 224 * appended or removed algorithms from that list then prefer algorithms 225 * that are in the list that are supported by known_hosts keys. 226 */ 227 if (options.hostkeyalgorithms == NULL || 228 options.hostkeyalgorithms[0] == '-' || 229 options.hostkeyalgorithms[0] == '+') 230 use_known_hosts_order = 1; 231 232 /* Expand or fill in HostkeyAlgorithms */ 233 all_key = sshkey_alg_list(0, 0, 1, ','); 234 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 235 kex_default_pk_alg(), all_key)) != 0) 236 fatal_fr(r, "kex_assemble_namelist"); 237 free(all_key); 238 239 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 240 fatal_f("kex_names_cat"); 241 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, s); 242 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 243 compat_cipher_proposal(ssh, options.ciphers); 244 myproposal[PROPOSAL_ENC_ALGS_STOC] = 245 compat_cipher_proposal(ssh, options.ciphers); 246 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 247 myproposal[PROPOSAL_COMP_ALGS_STOC] = 248 (char *)compression_alg_list(options.compression); 249 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 250 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 251 if (use_known_hosts_order) { 252 /* Query known_hosts and prefer algorithms that appear there */ 253 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 254 compat_pkalg_proposal(ssh, 255 order_hostkeyalgs(host, hostaddr, port, cinfo)); 256 } else { 257 /* Use specified HostkeyAlgorithms exactly */ 258 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 259 compat_pkalg_proposal(ssh, options.hostkeyalgorithms); 260 } 261 262 if (options.rekey_limit || options.rekey_interval) 263 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 264 options.rekey_interval); 265 266 /* start key exchange */ 267 if ((r = kex_setup(ssh, myproposal)) != 0) 268 fatal_r(r, "kex_setup"); 269 #ifdef WITH_OPENSSL 270 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 271 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 272 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 273 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 274 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 275 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 276 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 277 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 278 #endif 279 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 280 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 281 ssh->kex->verify_host_key=&verify_host_key_callback; 282 283 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 284 285 /* remove ext-info from the KEX proposals for rekeying */ 286 myproposal[PROPOSAL_KEX_ALGS] = 287 compat_kex_proposal(ssh, options.kex_algorithms); 288 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 289 fatal_r(r, "kex_prop2buf"); 290 291 #ifdef DEBUG_KEXDH 292 /* send 1st encrypted/maced/compressed message */ 293 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 294 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 295 (r = sshpkt_send(ssh)) != 0 || 296 (r = ssh_packet_write_wait(ssh)) != 0) 297 fatal_fr(r, "send packet"); 298 #endif 299 } 300 301 /* 302 * Authenticate user 303 */ 304 305 typedef struct cauthctxt Authctxt; 306 typedef struct cauthmethod Authmethod; 307 typedef struct identity Identity; 308 typedef struct idlist Idlist; 309 310 struct identity { 311 TAILQ_ENTRY(identity) next; 312 int agent_fd; /* >=0 if agent supports key */ 313 struct sshkey *key; /* public/private key */ 314 char *filename; /* comment for agent-only keys */ 315 int tried; 316 int isprivate; /* key points to the private key */ 317 int userprovided; 318 }; 319 TAILQ_HEAD(idlist, identity); 320 321 struct cauthctxt { 322 const char *server_user; 323 const char *local_user; 324 const char *host; 325 const char *service; 326 struct cauthmethod *method; 327 sig_atomic_t success; 328 char *authlist; 329 #ifdef GSSAPI 330 /* gssapi */ 331 gss_OID_set gss_supported_mechs; 332 u_int mech_tried; 333 #endif 334 /* pubkey */ 335 struct idlist keys; 336 int agent_fd; 337 /* hostbased */ 338 Sensitive *sensitive; 339 char *oktypes, *ktypes; 340 const char *active_ktype; 341 /* kbd-interactive */ 342 int info_req_seen; 343 int attempt_kbdint; 344 /* password */ 345 int attempt_passwd; 346 /* generic */ 347 void *methoddata; 348 }; 349 350 struct cauthmethod { 351 char *name; /* string to compare against server's list */ 352 int (*userauth)(struct ssh *ssh); 353 void (*cleanup)(struct ssh *ssh); 354 int *enabled; /* flag in option struct that enables method */ 355 int *batch_flag; /* flag in option struct that disables method */ 356 }; 357 358 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 359 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 360 static int input_userauth_success(int, u_int32_t, struct ssh *); 361 static int input_userauth_failure(int, u_int32_t, struct ssh *); 362 static int input_userauth_banner(int, u_int32_t, struct ssh *); 363 static int input_userauth_error(int, u_int32_t, struct ssh *); 364 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 365 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 366 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 367 368 static int userauth_none(struct ssh *); 369 static int userauth_pubkey(struct ssh *); 370 static int userauth_passwd(struct ssh *); 371 static int userauth_kbdint(struct ssh *); 372 static int userauth_hostbased(struct ssh *); 373 374 #ifdef GSSAPI 375 static int userauth_gssapi(struct ssh *); 376 static void userauth_gssapi_cleanup(struct ssh *); 377 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 378 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 379 static int input_gssapi_error(int, u_int32_t, struct ssh *); 380 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 381 #endif 382 383 void userauth(struct ssh *, char *); 384 385 static void pubkey_cleanup(struct ssh *); 386 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 387 static void pubkey_prepare(Authctxt *); 388 static void pubkey_reset(Authctxt *); 389 static struct sshkey *load_identity_file(Identity *); 390 391 static Authmethod *authmethod_get(char *authlist); 392 static Authmethod *authmethod_lookup(const char *name); 393 static char *authmethods_get(void); 394 395 Authmethod authmethods[] = { 396 #ifdef GSSAPI 397 {"gssapi-with-mic", 398 userauth_gssapi, 399 userauth_gssapi_cleanup, 400 &options.gss_authentication, 401 NULL}, 402 #endif 403 {"hostbased", 404 userauth_hostbased, 405 NULL, 406 &options.hostbased_authentication, 407 NULL}, 408 {"publickey", 409 userauth_pubkey, 410 NULL, 411 &options.pubkey_authentication, 412 NULL}, 413 {"keyboard-interactive", 414 userauth_kbdint, 415 NULL, 416 &options.kbd_interactive_authentication, 417 &options.batch_mode}, 418 {"password", 419 userauth_passwd, 420 NULL, 421 &options.password_authentication, 422 &options.batch_mode}, 423 {"none", 424 userauth_none, 425 NULL, 426 NULL, 427 NULL}, 428 {NULL, NULL, NULL, NULL, NULL} 429 }; 430 431 void 432 ssh_userauth2(struct ssh *ssh, const char *local_user, 433 const char *server_user, char *host, Sensitive *sensitive) 434 { 435 Authctxt authctxt; 436 int r; 437 438 if (options.preferred_authentications == NULL) 439 options.preferred_authentications = authmethods_get(); 440 441 /* setup authentication context */ 442 memset(&authctxt, 0, sizeof(authctxt)); 443 authctxt.server_user = server_user; 444 authctxt.local_user = local_user; 445 authctxt.host = host; 446 authctxt.service = "ssh-connection"; /* service name */ 447 authctxt.success = 0; 448 authctxt.method = authmethod_lookup("none"); 449 authctxt.authlist = NULL; 450 authctxt.methoddata = NULL; 451 authctxt.sensitive = sensitive; 452 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 453 authctxt.info_req_seen = 0; 454 authctxt.attempt_kbdint = 0; 455 authctxt.attempt_passwd = 0; 456 #if GSSAPI 457 authctxt.gss_supported_mechs = NULL; 458 authctxt.mech_tried = 0; 459 #endif 460 authctxt.agent_fd = -1; 461 pubkey_prepare(&authctxt); 462 if (authctxt.method == NULL) { 463 fatal_f("internal error: cannot send userauth none request"); 464 } 465 466 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 467 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 468 (r = sshpkt_send(ssh)) != 0) 469 fatal_fr(r, "send packet"); 470 471 ssh->authctxt = &authctxt; 472 ssh_dispatch_init(ssh, &input_userauth_error); 473 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 474 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 475 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 476 pubkey_cleanup(ssh); 477 ssh->authctxt = NULL; 478 479 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 480 481 if (!authctxt.success) 482 fatal("Authentication failed."); 483 if (ssh_packet_connection_is_on_socket(ssh)) { 484 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 485 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 486 authctxt.method->name); 487 } else { 488 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 489 authctxt.method->name); 490 } 491 } 492 493 /* ARGSUSED */ 494 static int 495 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 496 { 497 int r; 498 499 if (ssh_packet_remaining(ssh) > 0) { 500 char *reply; 501 502 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 503 goto out; 504 debug2("service_accept: %s", reply); 505 free(reply); 506 } else { 507 debug2("buggy server: service_accept w/o service"); 508 } 509 if ((r = sshpkt_get_end(ssh)) != 0) 510 goto out; 511 debug("SSH2_MSG_SERVICE_ACCEPT received"); 512 513 /* initial userauth request */ 514 userauth_none(ssh); 515 516 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 517 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 519 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 520 r = 0; 521 out: 522 return r; 523 } 524 525 /* ARGSUSED */ 526 static int 527 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 528 { 529 return kex_input_ext_info(type, seqnr, ssh); 530 } 531 532 void 533 userauth(struct ssh *ssh, char *authlist) 534 { 535 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 536 537 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 538 authctxt->method->cleanup(ssh); 539 540 free(authctxt->methoddata); 541 authctxt->methoddata = NULL; 542 if (authlist == NULL) { 543 authlist = authctxt->authlist; 544 } else { 545 free(authctxt->authlist); 546 authctxt->authlist = authlist; 547 } 548 for (;;) { 549 Authmethod *method = authmethod_get(authlist); 550 if (method == NULL) 551 fatal("%s@%s: Permission denied (%s).", 552 authctxt->server_user, authctxt->host, authlist); 553 authctxt->method = method; 554 555 /* reset the per method handler */ 556 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 557 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 558 559 /* and try new method */ 560 if (method->userauth(ssh) != 0) { 561 debug2("we sent a %s packet, wait for reply", method->name); 562 break; 563 } else { 564 debug2("we did not send a packet, disable method"); 565 method->enabled = NULL; 566 } 567 } 568 } 569 570 /* ARGSUSED */ 571 static int 572 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 573 { 574 fatal_f("bad message during authentication: type %d", type); 575 return 0; 576 } 577 578 /* ARGSUSED */ 579 static int 580 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 581 { 582 char *msg = NULL; 583 size_t len; 584 int r; 585 586 debug3_f("entering"); 587 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 588 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 589 goto out; 590 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 591 fmprintf(stderr, "%s", msg); 592 r = 0; 593 out: 594 free(msg); 595 return r; 596 } 597 598 /* ARGSUSED */ 599 static int 600 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 601 { 602 Authctxt *authctxt = ssh->authctxt; 603 604 if (authctxt == NULL) 605 fatal_f("no authentication context"); 606 free(authctxt->authlist); 607 authctxt->authlist = NULL; 608 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 609 authctxt->method->cleanup(ssh); 610 free(authctxt->methoddata); 611 authctxt->methoddata = NULL; 612 authctxt->success = 1; /* break out */ 613 return 0; 614 } 615 616 #if 0 617 static int 618 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 619 { 620 Authctxt *authctxt = ssh->authctxt; 621 622 if (authctxt == NULL) 623 fatal_f("no authentication context"); 624 625 fatal("Unexpected authentication success during %s.", 626 authctxt->method->name); 627 return 0; 628 } 629 #endif 630 631 /* ARGSUSED */ 632 static int 633 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 634 { 635 Authctxt *authctxt = ssh->authctxt; 636 char *authlist = NULL; 637 u_char partial; 638 639 if (authctxt == NULL) 640 fatal("input_userauth_failure: no authentication context"); 641 642 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 643 sshpkt_get_u8(ssh, &partial) != 0 || 644 sshpkt_get_end(ssh) != 0) 645 goto out; 646 647 if (partial != 0) { 648 verbose("Authenticated using \"%s\" with partial success.", 649 authctxt->method->name); 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 ssh->kex->session_id); 876 877 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 878 fatal_f("sshbuf_mutable_ptr failed"); 879 gssbuf.length = sshbuf_len(b); 880 881 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 882 883 if (!GSS_ERROR(status)) { 884 if ((r = sshpkt_start(ssh, 885 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 886 (r = sshpkt_put_string(ssh, mic.value, 887 mic.length)) != 0 || 888 (r = sshpkt_send(ssh)) != 0) 889 fatal_fr(r, "send MIC"); 890 } 891 892 sshbuf_free(b); 893 gss_release_buffer(&ms, &mic); 894 } 895 } 896 897 return status; 898 } 899 900 /* ARGSUSED */ 901 static int 902 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 903 { 904 Authctxt *authctxt = ssh->authctxt; 905 Gssctxt *gssctxt; 906 size_t oidlen; 907 u_char *oidv = NULL; 908 int r; 909 910 if (authctxt == NULL) 911 fatal("input_gssapi_response: no authentication context"); 912 gssctxt = authctxt->methoddata; 913 914 /* Setup our OID */ 915 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 916 goto done; 917 918 if (oidlen <= 2 || 919 oidv[0] != SSH_GSS_OIDTYPE || 920 oidv[1] != oidlen - 2) { 921 debug("Badly encoded mechanism OID received"); 922 userauth(ssh, NULL); 923 goto ok; 924 } 925 926 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 927 fatal("Server returned different OID than expected"); 928 929 if ((r = sshpkt_get_end(ssh)) != 0) 930 goto done; 931 932 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 933 /* Start again with next method on list */ 934 debug("Trying to start again"); 935 userauth(ssh, NULL); 936 goto ok; 937 } 938 ok: 939 r = 0; 940 done: 941 free(oidv); 942 return r; 943 } 944 945 /* ARGSUSED */ 946 static int 947 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 948 { 949 Authctxt *authctxt = ssh->authctxt; 950 gss_buffer_desc recv_tok; 951 u_char *p = NULL; 952 size_t len; 953 OM_uint32 status; 954 int r; 955 956 if (authctxt == NULL) 957 fatal("input_gssapi_response: no authentication context"); 958 959 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 960 (r = sshpkt_get_end(ssh)) != 0) 961 goto out; 962 963 recv_tok.value = p; 964 recv_tok.length = len; 965 status = process_gssapi_token(ssh, &recv_tok); 966 967 /* Start again with the next method in the list */ 968 if (GSS_ERROR(status)) { 969 userauth(ssh, NULL); 970 /* ok */ 971 } 972 r = 0; 973 out: 974 free(p); 975 return r; 976 } 977 978 /* ARGSUSED */ 979 static int 980 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 981 { 982 Authctxt *authctxt = ssh->authctxt; 983 Gssctxt *gssctxt; 984 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 985 gss_buffer_desc recv_tok; 986 OM_uint32 ms; 987 u_char *p = NULL; 988 size_t len; 989 int r; 990 991 if (authctxt == NULL) 992 fatal("input_gssapi_response: no authentication context"); 993 gssctxt = authctxt->methoddata; 994 995 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 996 (r = sshpkt_get_end(ssh)) != 0) { 997 free(p); 998 return r; 999 } 1000 1001 /* Stick it into GSSAPI and see what it says */ 1002 recv_tok.value = p; 1003 recv_tok.length = len; 1004 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1005 &recv_tok, &send_tok, NULL); 1006 free(p); 1007 gss_release_buffer(&ms, &send_tok); 1008 1009 /* Server will be returning a failed packet after this one */ 1010 return 0; 1011 } 1012 1013 /* ARGSUSED */ 1014 static int 1015 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1016 { 1017 char *msg = NULL; 1018 char *lang = NULL; 1019 int r; 1020 1021 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1022 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1023 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1024 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1025 goto out; 1026 r = sshpkt_get_end(ssh); 1027 debug("Server GSSAPI Error:\n%s", msg); 1028 out: 1029 free(msg); 1030 free(lang); 1031 return r; 1032 } 1033 #endif /* GSSAPI */ 1034 1035 static int 1036 userauth_none(struct ssh *ssh) 1037 { 1038 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1039 int r; 1040 1041 /* initial userauth request */ 1042 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1043 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1044 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1045 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1046 (r = sshpkt_send(ssh)) != 0) 1047 fatal_fr(r, "send packet"); 1048 return 1; 1049 } 1050 1051 static int 1052 userauth_passwd(struct ssh *ssh) 1053 { 1054 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1055 char *password, *prompt = NULL; 1056 const char *host = options.host_key_alias ? options.host_key_alias : 1057 authctxt->host; 1058 int r; 1059 1060 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1061 return 0; 1062 1063 if (authctxt->attempt_passwd != 1) 1064 error("Permission denied, please try again."); 1065 1066 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1067 password = read_passphrase(prompt, 0); 1068 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1069 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1070 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1071 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1072 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1073 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1074 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1075 (r = sshpkt_send(ssh)) != 0) 1076 fatal_fr(r, "send packet"); 1077 1078 free(prompt); 1079 if (password != NULL) 1080 freezero(password, strlen(password)); 1081 1082 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1083 &input_userauth_passwd_changereq); 1084 1085 return 1; 1086 } 1087 1088 /* 1089 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1090 */ 1091 /* ARGSUSED */ 1092 static int 1093 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1094 { 1095 Authctxt *authctxt = ssh->authctxt; 1096 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1097 char prompt[256]; 1098 const char *host; 1099 int r; 1100 1101 debug2("input_userauth_passwd_changereq"); 1102 1103 if (authctxt == NULL) 1104 fatal("input_userauth_passwd_changereq: " 1105 "no authentication context"); 1106 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1107 1108 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1109 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1110 goto out; 1111 if (strlen(info) > 0) 1112 logit("%s", info); 1113 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1114 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1115 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1116 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1117 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1118 goto out; 1119 1120 snprintf(prompt, sizeof(prompt), 1121 "Enter %.30s@%.128s's old password: ", 1122 authctxt->server_user, host); 1123 password = read_passphrase(prompt, 0); 1124 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1125 goto out; 1126 1127 freezero(password, strlen(password)); 1128 password = NULL; 1129 while (password == NULL) { 1130 snprintf(prompt, sizeof(prompt), 1131 "Enter %.30s@%.128s's new password: ", 1132 authctxt->server_user, host); 1133 password = read_passphrase(prompt, RP_ALLOW_EOF); 1134 if (password == NULL) { 1135 /* bail out */ 1136 r = 0; 1137 goto out; 1138 } 1139 snprintf(prompt, sizeof(prompt), 1140 "Retype %.30s@%.128s's new password: ", 1141 authctxt->server_user, host); 1142 retype = read_passphrase(prompt, 0); 1143 if (strcmp(password, retype) != 0) { 1144 freezero(password, strlen(password)); 1145 logit("Mismatch; try again, EOF to quit."); 1146 password = NULL; 1147 } 1148 freezero(retype, strlen(retype)); 1149 } 1150 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1151 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1152 (r = sshpkt_send(ssh)) != 0) 1153 goto out; 1154 1155 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1156 &input_userauth_passwd_changereq); 1157 r = 0; 1158 out: 1159 if (password) 1160 freezero(password, strlen(password)); 1161 free(info); 1162 free(lang); 1163 return r; 1164 } 1165 1166 /* 1167 * Select an algorithm for publickey signatures. 1168 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1169 * 1170 * Call with ssh==NULL to ignore server-sig-algs extension list and 1171 * only attempt with the key's base signature type. 1172 */ 1173 static char * 1174 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1175 { 1176 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1177 const char *server_sig_algs; 1178 1179 /* 1180 * The signature algorithm will only differ from the key algorithm 1181 * for RSA keys/certs and when the server advertises support for 1182 * newer (SHA2) algorithms. 1183 */ 1184 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1185 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1186 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1187 /* Filter base key signature alg against our configuration */ 1188 return match_list(sshkey_ssh_name(key), 1189 options.pubkey_accepted_algos, NULL); 1190 } 1191 1192 /* 1193 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1194 * fails to advertise it via SSH2_MSG_EXT_INFO. 1195 */ 1196 server_sig_algs = ssh->kex->server_sig_algs; 1197 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1198 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1199 1200 /* 1201 * For RSA keys/certs, since these might have a different sig type: 1202 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1203 * that also appears in the supported signature algorithms list from 1204 * the server. 1205 */ 1206 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1207 while ((cp = strsep(&allowed, ",")) != NULL) { 1208 if (sshkey_type_from_name(cp) != key->type) 1209 continue; 1210 tmp = match_list(sshkey_sigalg_by_name(cp), 1211 server_sig_algs, NULL); 1212 if (tmp != NULL) 1213 alg = xstrdup(cp); 1214 free(tmp); 1215 if (alg != NULL) 1216 break; 1217 } 1218 free(oallowed); 1219 return alg; 1220 } 1221 1222 static int 1223 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1224 const u_char *data, size_t datalen, u_int compat, const char *alg) 1225 { 1226 struct sshkey *sign_key = NULL, *prv = NULL; 1227 int retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1228 struct notifier_ctx *notifier = NULL; 1229 char *fp = NULL, *pin = NULL, *prompt = NULL; 1230 1231 *sigp = NULL; 1232 *lenp = 0; 1233 1234 /* The agent supports this key. */ 1235 if (id->key != NULL && id->agent_fd != -1) { 1236 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1237 data, datalen, alg, compat); 1238 } 1239 1240 /* 1241 * We have already loaded the private key or the private key is 1242 * stored in external hardware. 1243 */ 1244 if (id->key != NULL && 1245 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1246 sign_key = id->key; 1247 } else { 1248 /* Load the private key from the file. */ 1249 if ((prv = load_identity_file(id)) == NULL) 1250 return SSH_ERR_KEY_NOT_FOUND; 1251 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1252 error_f("private key %s contents do not match public", 1253 id->filename); 1254 r = SSH_ERR_KEY_NOT_FOUND; 1255 goto out; 1256 } 1257 sign_key = prv; 1258 if (sshkey_is_sk(sign_key)) { 1259 if ((sign_key->sk_flags & 1260 SSH_SK_USER_VERIFICATION_REQD)) { 1261 retry_pin: 1262 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1263 sshkey_type(sign_key), id->filename); 1264 pin = read_passphrase(prompt, 0); 1265 } 1266 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1267 /* XXX should batch mode just skip these? */ 1268 if ((fp = sshkey_fingerprint(sign_key, 1269 options.fingerprint_hash, 1270 SSH_FP_DEFAULT)) == NULL) 1271 fatal_f("fingerprint failed"); 1272 notifier = notify_start(options.batch_mode, 1273 "Confirm user presence for key %s %s", 1274 sshkey_type(sign_key), fp); 1275 free(fp); 1276 } 1277 } 1278 } 1279 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1280 alg, options.sk_provider, pin, compat)) != 0) { 1281 debug_fr(r, "sshkey_sign"); 1282 if (pin == NULL && !retried && sshkey_is_sk(sign_key) && 1283 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1284 notify_complete(notifier, NULL); 1285 notifier = NULL; 1286 retried = 1; 1287 goto retry_pin; 1288 } 1289 goto out; 1290 } 1291 1292 /* 1293 * PKCS#11 tokens may not support all signature algorithms, 1294 * so check what we get back. 1295 */ 1296 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1297 debug_fr(r, "sshkey_check_sigtype"); 1298 goto out; 1299 } 1300 /* success */ 1301 r = 0; 1302 out: 1303 free(prompt); 1304 if (pin != NULL) 1305 freezero(pin, strlen(pin)); 1306 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1307 sshkey_free(prv); 1308 return r; 1309 } 1310 1311 static int 1312 id_filename_matches(Identity *id, Identity *private_id) 1313 { 1314 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1315 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1316 size_t i, slen; 1317 1318 if (strcmp(id->filename, private_id->filename) == 0) 1319 return 1; 1320 for (i = 0; suffixes[i]; i++) { 1321 slen = strlen(suffixes[i]); 1322 if (len > slen && plen == len - slen && 1323 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1324 memcmp(id->filename, private_id->filename, plen) == 0) 1325 return 1; 1326 } 1327 return 0; 1328 } 1329 1330 static int 1331 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1332 { 1333 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1334 struct sshbuf *b = NULL; 1335 Identity *private_id, *sign_id = NULL; 1336 u_char *signature = NULL; 1337 size_t slen = 0, skip = 0; 1338 int r, fallback_sigtype, sent = 0; 1339 char *alg = NULL, *fp = NULL; 1340 const char *loc = ""; 1341 1342 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1343 SSH_FP_DEFAULT)) == NULL) 1344 return 0; 1345 1346 debug3_f("%s %s", sshkey_type(id->key), fp); 1347 1348 /* 1349 * If the key is an certificate, try to find a matching private key 1350 * and use it to complete the signature. 1351 * If no such private key exists, fall back to trying the certificate 1352 * key itself in case it has a private half already loaded. 1353 * This will try to set sign_id to the private key that will perform 1354 * the signature. 1355 */ 1356 if (sshkey_is_cert(id->key)) { 1357 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1358 if (sshkey_equal_public(id->key, private_id->key) && 1359 id->key->type != private_id->key->type) { 1360 sign_id = private_id; 1361 break; 1362 } 1363 } 1364 /* 1365 * Exact key matches are preferred, but also allow 1366 * filename matches for non-PKCS#11/agent keys that 1367 * didn't load public keys. This supports the case 1368 * of keeping just a private key file and public 1369 * certificate on disk. 1370 */ 1371 if (sign_id == NULL && 1372 !id->isprivate && id->agent_fd == -1 && 1373 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1374 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1375 if (private_id->key == NULL && 1376 id_filename_matches(id, private_id)) { 1377 sign_id = private_id; 1378 break; 1379 } 1380 } 1381 } 1382 if (sign_id != NULL) { 1383 debug2_f("using private key \"%s\"%s for " 1384 "certificate", sign_id->filename, 1385 sign_id->agent_fd != -1 ? " from agent" : ""); 1386 } else { 1387 debug_f("no separate private key for certificate " 1388 "\"%s\"", id->filename); 1389 } 1390 } 1391 1392 /* 1393 * If the above didn't select another identity to do the signing 1394 * then default to the one we started with. 1395 */ 1396 if (sign_id == NULL) 1397 sign_id = id; 1398 1399 /* assemble and sign data */ 1400 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1401 free(alg); 1402 slen = 0; 1403 signature = NULL; 1404 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1405 id->key)) == NULL) { 1406 error_f("no mutual signature supported"); 1407 goto out; 1408 } 1409 debug3_f("signing using %s %s", alg, fp); 1410 1411 sshbuf_free(b); 1412 if ((b = sshbuf_new()) == NULL) 1413 fatal_f("sshbuf_new failed"); 1414 if (ssh->compat & SSH_OLD_SESSIONID) { 1415 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1416 fatal_fr(r, "sshbuf_putb"); 1417 } else { 1418 if ((r = sshbuf_put_stringb(b, 1419 ssh->kex->session_id)) != 0) 1420 fatal_fr(r, "sshbuf_put_stringb"); 1421 } 1422 skip = sshbuf_len(b); 1423 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1424 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1425 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1426 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1427 (r = sshbuf_put_u8(b, 1)) != 0 || 1428 (r = sshbuf_put_cstring(b, alg)) != 0 || 1429 (r = sshkey_puts(id->key, b)) != 0) { 1430 fatal_fr(r, "assemble signed data"); 1431 } 1432 1433 /* generate signature */ 1434 r = identity_sign(sign_id, &signature, &slen, 1435 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1436 if (r == 0) 1437 break; 1438 else if (r == SSH_ERR_KEY_NOT_FOUND) 1439 goto out; /* soft failure */ 1440 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1441 !fallback_sigtype) { 1442 if (sign_id->agent_fd != -1) 1443 loc = "agent "; 1444 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1445 loc = "token "; 1446 logit("%skey %s %s returned incorrect signature type", 1447 loc, sshkey_type(id->key), fp); 1448 continue; 1449 } 1450 error_fr(r, "signing failed for %s \"%s\"%s", 1451 sshkey_type(sign_id->key), sign_id->filename, 1452 id->agent_fd != -1 ? " from agent" : ""); 1453 goto out; 1454 } 1455 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1456 fatal_f("no signature"); 1457 1458 /* append signature */ 1459 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1460 fatal_fr(r, "append signature"); 1461 1462 #ifdef DEBUG_PK 1463 sshbuf_dump(b, stderr); 1464 #endif 1465 /* skip session id and packet type */ 1466 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1467 fatal_fr(r, "consume"); 1468 1469 /* put remaining data from buffer into packet */ 1470 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1471 (r = sshpkt_putb(ssh, b)) != 0 || 1472 (r = sshpkt_send(ssh)) != 0) 1473 fatal_fr(r, "enqueue request"); 1474 1475 /* success */ 1476 sent = 1; 1477 1478 out: 1479 free(fp); 1480 free(alg); 1481 sshbuf_free(b); 1482 freezero(signature, slen); 1483 return sent; 1484 } 1485 1486 static int 1487 send_pubkey_test(struct ssh *ssh, Identity *id) 1488 { 1489 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1490 u_char *blob = NULL; 1491 char *alg = NULL; 1492 size_t bloblen; 1493 u_int have_sig = 0; 1494 int sent = 0, r; 1495 1496 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1497 debug_f("no mutual signature algorithm"); 1498 goto out; 1499 } 1500 1501 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1502 /* we cannot handle this key */ 1503 debug3_f("cannot handle key"); 1504 goto out; 1505 } 1506 /* register callback for USERAUTH_PK_OK message */ 1507 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1508 1509 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1510 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1511 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1512 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1513 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1514 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1515 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1516 (r = sshpkt_send(ssh)) != 0) 1517 fatal_fr(r, "send packet"); 1518 sent = 1; 1519 1520 out: 1521 free(alg); 1522 free(blob); 1523 return sent; 1524 } 1525 1526 static struct sshkey * 1527 load_identity_file(Identity *id) 1528 { 1529 struct sshkey *private = NULL; 1530 char prompt[300], *passphrase, *comment; 1531 int r, quit = 0, i; 1532 struct stat st; 1533 1534 if (stat(id->filename, &st) == -1) { 1535 do_log2(id->userprovided ? 1536 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1537 "no such identity: %s: %s", id->filename, strerror(errno)); 1538 return NULL; 1539 } 1540 snprintf(prompt, sizeof prompt, 1541 "Enter passphrase for key '%.100s': ", id->filename); 1542 for (i = 0; i <= options.number_of_password_prompts; i++) { 1543 if (i == 0) 1544 passphrase = ""; 1545 else { 1546 passphrase = read_passphrase(prompt, 0); 1547 if (*passphrase == '\0') { 1548 debug2("no passphrase given, try next key"); 1549 free(passphrase); 1550 break; 1551 } 1552 } 1553 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1554 passphrase, &private, &comment))) { 1555 case 0: 1556 break; 1557 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1558 if (options.batch_mode) { 1559 quit = 1; 1560 break; 1561 } 1562 if (i != 0) 1563 debug2("bad passphrase given, try again..."); 1564 break; 1565 case SSH_ERR_SYSTEM_ERROR: 1566 if (errno == ENOENT) { 1567 debug2_r(r, "Load key \"%s\"", id->filename); 1568 quit = 1; 1569 break; 1570 } 1571 /* FALLTHROUGH */ 1572 default: 1573 error_r(r, "Load key \"%s\"", id->filename); 1574 quit = 1; 1575 break; 1576 } 1577 if (private != NULL && sshkey_is_sk(private) && 1578 options.sk_provider == NULL) { 1579 debug("key \"%s\" is an authenticator-hosted key, " 1580 "but no provider specified", id->filename); 1581 sshkey_free(private); 1582 private = NULL; 1583 quit = 1; 1584 } 1585 if (!quit && private != NULL && id->agent_fd == -1 && 1586 !(id->key && id->isprivate)) 1587 maybe_add_key_to_agent(id->filename, private, comment, 1588 passphrase); 1589 if (i > 0) 1590 freezero(passphrase, strlen(passphrase)); 1591 free(comment); 1592 if (private != NULL || quit) 1593 break; 1594 } 1595 return private; 1596 } 1597 1598 static int 1599 key_type_allowed_by_config(struct sshkey *key) 1600 { 1601 if (match_pattern_list(sshkey_ssh_name(key), 1602 options.pubkey_accepted_algos, 0) == 1) 1603 return 1; 1604 1605 /* RSA keys/certs might be allowed by alternate signature types */ 1606 switch (key->type) { 1607 case KEY_RSA: 1608 if (match_pattern_list("rsa-sha2-512", 1609 options.pubkey_accepted_algos, 0) == 1) 1610 return 1; 1611 if (match_pattern_list("rsa-sha2-256", 1612 options.pubkey_accepted_algos, 0) == 1) 1613 return 1; 1614 break; 1615 case KEY_RSA_CERT: 1616 if (match_pattern_list("rsa-sha2-512-cert-v01 (at) openssh.com", 1617 options.pubkey_accepted_algos, 0) == 1) 1618 return 1; 1619 if (match_pattern_list("rsa-sha2-256-cert-v01 (at) openssh.com", 1620 options.pubkey_accepted_algos, 0) == 1) 1621 return 1; 1622 break; 1623 } 1624 return 0; 1625 } 1626 1627 1628 /* 1629 * try keys in the following order: 1630 * 1. certificates listed in the config file 1631 * 2. other input certificates 1632 * 3. agent keys that are found in the config file 1633 * 4. other agent keys 1634 * 5. keys that are only listed in the config file 1635 */ 1636 static void 1637 pubkey_prepare(Authctxt *authctxt) 1638 { 1639 struct identity *id, *id2, *tmp; 1640 struct idlist agent, files, *preferred; 1641 struct sshkey *key; 1642 int agent_fd = -1, i, r, found; 1643 size_t j; 1644 struct ssh_identitylist *idlist; 1645 char *ident; 1646 1647 TAILQ_INIT(&agent); /* keys from the agent */ 1648 TAILQ_INIT(&files); /* keys from the config file */ 1649 preferred = &authctxt->keys; 1650 TAILQ_INIT(preferred); /* preferred order of keys */ 1651 1652 /* list of keys stored in the filesystem and PKCS#11 */ 1653 for (i = 0; i < options.num_identity_files; i++) { 1654 key = options.identity_keys[i]; 1655 if (key && key->cert && 1656 key->cert->type != SSH2_CERT_TYPE_USER) { 1657 debug_f("ignoring certificate %s: not a user " 1658 "certificate", options.identity_files[i]); 1659 continue; 1660 } 1661 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1662 debug_f("ignoring authenticator-hosted key %s as no " 1663 "SecurityKeyProvider has been specified", 1664 options.identity_files[i]); 1665 continue; 1666 } 1667 options.identity_keys[i] = NULL; 1668 id = xcalloc(1, sizeof(*id)); 1669 id->agent_fd = -1; 1670 id->key = key; 1671 id->filename = xstrdup(options.identity_files[i]); 1672 id->userprovided = options.identity_file_userprovided[i]; 1673 TAILQ_INSERT_TAIL(&files, id, next); 1674 } 1675 /* list of certificates specified by user */ 1676 for (i = 0; i < options.num_certificate_files; i++) { 1677 key = options.certificates[i]; 1678 if (!sshkey_is_cert(key) || key->cert == NULL || 1679 key->cert->type != SSH2_CERT_TYPE_USER) { 1680 debug_f("ignoring certificate %s: not a user " 1681 "certificate", options.identity_files[i]); 1682 continue; 1683 } 1684 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1685 debug_f("ignoring authenticator-hosted key " 1686 "certificate %s as no " 1687 "SecurityKeyProvider has been specified", 1688 options.identity_files[i]); 1689 continue; 1690 } 1691 id = xcalloc(1, sizeof(*id)); 1692 id->agent_fd = -1; 1693 id->key = key; 1694 id->filename = xstrdup(options.certificate_files[i]); 1695 id->userprovided = options.certificate_file_userprovided[i]; 1696 TAILQ_INSERT_TAIL(preferred, id, next); 1697 } 1698 /* list of keys supported by the agent */ 1699 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1700 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1701 debug_fr(r, "ssh_get_authentication_socket"); 1702 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1703 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1704 debug_fr(r, "ssh_fetch_identitylist"); 1705 close(agent_fd); 1706 } else { 1707 for (j = 0; j < idlist->nkeys; j++) { 1708 found = 0; 1709 TAILQ_FOREACH(id, &files, next) { 1710 /* 1711 * agent keys from the config file are 1712 * preferred 1713 */ 1714 if (sshkey_equal(idlist->keys[j], id->key)) { 1715 TAILQ_REMOVE(&files, id, next); 1716 TAILQ_INSERT_TAIL(preferred, id, next); 1717 id->agent_fd = agent_fd; 1718 found = 1; 1719 break; 1720 } 1721 } 1722 if (!found && !options.identities_only) { 1723 id = xcalloc(1, sizeof(*id)); 1724 /* XXX "steals" key/comment from idlist */ 1725 id->key = idlist->keys[j]; 1726 id->filename = idlist->comments[j]; 1727 idlist->keys[j] = NULL; 1728 idlist->comments[j] = NULL; 1729 id->agent_fd = agent_fd; 1730 TAILQ_INSERT_TAIL(&agent, id, next); 1731 } 1732 } 1733 ssh_free_identitylist(idlist); 1734 /* append remaining agent keys */ 1735 TAILQ_CONCAT(preferred, &agent, next); 1736 authctxt->agent_fd = agent_fd; 1737 } 1738 /* Prefer PKCS11 keys that are explicitly listed */ 1739 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1740 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1741 continue; 1742 found = 0; 1743 TAILQ_FOREACH(id2, &files, next) { 1744 if (id2->key == NULL || 1745 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1746 continue; 1747 if (sshkey_equal(id->key, id2->key)) { 1748 TAILQ_REMOVE(&files, id, next); 1749 TAILQ_INSERT_TAIL(preferred, id, next); 1750 found = 1; 1751 break; 1752 } 1753 } 1754 /* If IdentitiesOnly set and key not found then don't use it */ 1755 if (!found && options.identities_only) { 1756 TAILQ_REMOVE(&files, id, next); 1757 freezero(id, sizeof(*id)); 1758 } 1759 } 1760 /* append remaining keys from the config file */ 1761 TAILQ_CONCAT(preferred, &files, next); 1762 /* finally, filter by PubkeyAcceptedAlgorithms */ 1763 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1764 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1765 debug("Skipping %s key %s - " 1766 "corresponding algo not in PubkeyAcceptedAlgorithms", 1767 sshkey_ssh_name(id->key), id->filename); 1768 TAILQ_REMOVE(preferred, id, next); 1769 sshkey_free(id->key); 1770 free(id->filename); 1771 memset(id, 0, sizeof(*id)); 1772 continue; 1773 } 1774 } 1775 /* List the keys we plan on using */ 1776 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1777 ident = format_identity(id); 1778 debug("Will attempt key: %s", ident); 1779 free(ident); 1780 } 1781 debug2_f("done"); 1782 } 1783 1784 static void 1785 pubkey_cleanup(struct ssh *ssh) 1786 { 1787 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1788 Identity *id; 1789 1790 if (authctxt->agent_fd != -1) { 1791 ssh_close_authentication_socket(authctxt->agent_fd); 1792 authctxt->agent_fd = -1; 1793 } 1794 for (id = TAILQ_FIRST(&authctxt->keys); id; 1795 id = TAILQ_FIRST(&authctxt->keys)) { 1796 TAILQ_REMOVE(&authctxt->keys, id, next); 1797 sshkey_free(id->key); 1798 free(id->filename); 1799 free(id); 1800 } 1801 } 1802 1803 static void 1804 pubkey_reset(Authctxt *authctxt) 1805 { 1806 Identity *id; 1807 1808 TAILQ_FOREACH(id, &authctxt->keys, next) 1809 id->tried = 0; 1810 } 1811 1812 static int 1813 try_identity(struct ssh *ssh, Identity *id) 1814 { 1815 if (!id->key) 1816 return (0); 1817 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1818 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 1819 debug("Skipped %s key %s for RSA/MD5 server", 1820 sshkey_type(id->key), id->filename); 1821 return (0); 1822 } 1823 return 1; 1824 } 1825 1826 static int 1827 userauth_pubkey(struct ssh *ssh) 1828 { 1829 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1830 Identity *id; 1831 int sent = 0; 1832 char *ident; 1833 1834 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1835 if (id->tried++) 1836 return (0); 1837 /* move key to the end of the queue */ 1838 TAILQ_REMOVE(&authctxt->keys, id, next); 1839 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1840 /* 1841 * send a test message if we have the public key. for 1842 * encrypted keys we cannot do this and have to load the 1843 * private key instead 1844 */ 1845 if (id->key != NULL) { 1846 if (try_identity(ssh, id)) { 1847 ident = format_identity(id); 1848 debug("Offering public key: %s", ident); 1849 free(ident); 1850 sent = send_pubkey_test(ssh, id); 1851 } 1852 } else { 1853 debug("Trying private key: %s", id->filename); 1854 id->key = load_identity_file(id); 1855 if (id->key != NULL) { 1856 if (try_identity(ssh, id)) { 1857 id->isprivate = 1; 1858 sent = sign_and_send_pubkey(ssh, id); 1859 } 1860 sshkey_free(id->key); 1861 id->key = NULL; 1862 id->isprivate = 0; 1863 } 1864 } 1865 if (sent) 1866 return (sent); 1867 } 1868 return (0); 1869 } 1870 1871 /* 1872 * Send userauth request message specifying keyboard-interactive method. 1873 */ 1874 static int 1875 userauth_kbdint(struct ssh *ssh) 1876 { 1877 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1878 int r; 1879 1880 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1881 return 0; 1882 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1883 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1884 debug3("userauth_kbdint: disable: no info_req_seen"); 1885 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1886 return 0; 1887 } 1888 1889 debug2("userauth_kbdint"); 1890 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1891 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1892 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1893 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1894 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1895 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1896 options.kbd_interactive_devices : "")) != 0 || 1897 (r = sshpkt_send(ssh)) != 0) 1898 fatal_fr(r, "send packet"); 1899 1900 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1901 return 1; 1902 } 1903 1904 /* 1905 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1906 */ 1907 static int 1908 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1909 { 1910 Authctxt *authctxt = ssh->authctxt; 1911 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1912 char *display_prompt = NULL, *response = NULL; 1913 u_char echo = 0; 1914 u_int num_prompts, i; 1915 int r; 1916 1917 debug2_f("entering"); 1918 1919 if (authctxt == NULL) 1920 fatal_f("no authentication context"); 1921 1922 authctxt->info_req_seen = 1; 1923 1924 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1925 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1926 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1927 goto out; 1928 if (strlen(name) > 0) 1929 logit("%s", name); 1930 if (strlen(inst) > 0) 1931 logit("%s", inst); 1932 1933 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1934 goto out; 1935 /* 1936 * Begin to build info response packet based on prompts requested. 1937 * We commit to providing the correct number of responses, so if 1938 * further on we run into a problem that prevents this, we have to 1939 * be sure and clean this up and send a correct error response. 1940 */ 1941 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1942 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1943 goto out; 1944 1945 debug2_f("num_prompts %d", num_prompts); 1946 for (i = 0; i < num_prompts; i++) { 1947 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1948 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1949 goto out; 1950 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1951 authctxt->server_user, options.host_key_alias ? 1952 options.host_key_alias : authctxt->host, prompt) == -1) 1953 fatal_f("asmprintf failed"); 1954 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1955 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1956 goto out; 1957 freezero(response, strlen(response)); 1958 free(prompt); 1959 free(display_prompt); 1960 display_prompt = response = prompt = NULL; 1961 } 1962 /* done with parsing incoming message. */ 1963 if ((r = sshpkt_get_end(ssh)) != 0 || 1964 (r = sshpkt_add_padding(ssh, 64)) != 0) 1965 goto out; 1966 r = sshpkt_send(ssh); 1967 out: 1968 if (response) 1969 freezero(response, strlen(response)); 1970 free(prompt); 1971 free(display_prompt); 1972 free(name); 1973 free(inst); 1974 free(lang); 1975 return r; 1976 } 1977 1978 static int 1979 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1980 const u_char *data, size_t datalen) 1981 { 1982 struct sshbuf *b; 1983 struct stat st; 1984 pid_t pid; 1985 int r, to[2], from[2], status; 1986 int sock = ssh_packet_get_connection_in(ssh); 1987 u_char rversion = 0, version = 2; 1988 void (*osigchld)(int); 1989 1990 *sigp = NULL; 1991 *lenp = 0; 1992 1993 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1994 error_f("not installed: %s", strerror(errno)); 1995 return -1; 1996 } 1997 if (fflush(stdout) != 0) { 1998 error_f("fflush: %s", strerror(errno)); 1999 return -1; 2000 } 2001 if (pipe(to) == -1) { 2002 error_f("pipe: %s", strerror(errno)); 2003 return -1; 2004 } 2005 if (pipe(from) == -1) { 2006 error_f("pipe: %s", strerror(errno)); 2007 return -1; 2008 } 2009 if ((pid = fork()) == -1) { 2010 error_f("fork: %s", strerror(errno)); 2011 return -1; 2012 } 2013 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2014 if (pid == 0) { 2015 close(from[0]); 2016 if (dup2(from[1], STDOUT_FILENO) == -1) 2017 fatal_f("dup2: %s", strerror(errno)); 2018 close(to[1]); 2019 if (dup2(to[0], STDIN_FILENO) == -1) 2020 fatal_f("dup2: %s", strerror(errno)); 2021 close(from[1]); 2022 close(to[0]); 2023 2024 if (dup2(sock, STDERR_FILENO + 1) == -1) 2025 fatal_f("dup2: %s", strerror(errno)); 2026 sock = STDERR_FILENO + 1; 2027 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2028 closefrom(sock + 1); 2029 2030 debug3_f("[child] pid=%ld, exec %s", 2031 (long)getpid(), _PATH_SSH_KEY_SIGN); 2032 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2033 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2034 strerror(errno)); 2035 } 2036 close(from[1]); 2037 close(to[0]); 2038 sock = STDERR_FILENO + 1; 2039 2040 if ((b = sshbuf_new()) == NULL) 2041 fatal_f("sshbuf_new failed"); 2042 /* send # of sock, data to be signed */ 2043 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2044 (r = sshbuf_put_string(b, data, datalen)) != 0) 2045 fatal_fr(r, "buffer error"); 2046 if (ssh_msg_send(to[1], version, b) == -1) 2047 fatal_f("couldn't send request"); 2048 sshbuf_reset(b); 2049 r = ssh_msg_recv(from[0], b); 2050 close(from[0]); 2051 close(to[1]); 2052 if (r < 0) { 2053 error_f("no reply"); 2054 goto fail; 2055 } 2056 2057 errno = 0; 2058 while (waitpid(pid, &status, 0) == -1) { 2059 if (errno != EINTR) { 2060 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2061 goto fail; 2062 } 2063 } 2064 if (!WIFEXITED(status)) { 2065 error_f("exited abnormally"); 2066 goto fail; 2067 } 2068 if (WEXITSTATUS(status) != 0) { 2069 error_f("exited with status %d", WEXITSTATUS(status)); 2070 goto fail; 2071 } 2072 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2073 error_fr(r, "buffer error"); 2074 goto fail; 2075 } 2076 if (rversion != version) { 2077 error_f("bad version"); 2078 goto fail; 2079 } 2080 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2081 error_fr(r, "buffer error"); 2082 fail: 2083 ssh_signal(SIGCHLD, osigchld); 2084 sshbuf_free(b); 2085 return -1; 2086 } 2087 ssh_signal(SIGCHLD, osigchld); 2088 sshbuf_free(b); 2089 2090 return 0; 2091 } 2092 2093 static int 2094 userauth_hostbased(struct ssh *ssh) 2095 { 2096 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2097 struct sshkey *private = NULL; 2098 struct sshbuf *b = NULL; 2099 u_char *sig = NULL, *keyblob = NULL; 2100 char *fp = NULL, *chost = NULL, *lname = NULL; 2101 size_t siglen = 0, keylen = 0; 2102 int i, r, success = 0; 2103 2104 if (authctxt->ktypes == NULL) { 2105 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2106 authctxt->ktypes = authctxt->oktypes; 2107 } 2108 2109 /* 2110 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2111 * trying each hostkey that matches the type in turn. 2112 */ 2113 for (;;) { 2114 if (authctxt->active_ktype == NULL) 2115 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2116 if (authctxt->active_ktype == NULL || 2117 *authctxt->active_ktype == '\0') 2118 break; 2119 debug3_f("trying key type %s", authctxt->active_ktype); 2120 2121 /* check for a useful key */ 2122 private = NULL; 2123 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2124 if (authctxt->sensitive->keys[i] == NULL || 2125 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2126 continue; 2127 if (match_pattern_list( 2128 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2129 authctxt->active_ktype, 0) != 1) 2130 continue; 2131 /* we take and free the key */ 2132 private = authctxt->sensitive->keys[i]; 2133 authctxt->sensitive->keys[i] = NULL; 2134 break; 2135 } 2136 /* Found one */ 2137 if (private != NULL) 2138 break; 2139 /* No more keys of this type; advance */ 2140 authctxt->active_ktype = NULL; 2141 } 2142 if (private == NULL) { 2143 free(authctxt->oktypes); 2144 authctxt->oktypes = authctxt->ktypes = NULL; 2145 authctxt->active_ktype = NULL; 2146 debug("No more client hostkeys for hostbased authentication."); 2147 goto out; 2148 } 2149 2150 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2151 SSH_FP_DEFAULT)) == NULL) { 2152 error_f("sshkey_fingerprint failed"); 2153 goto out; 2154 } 2155 debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp); 2156 2157 /* figure out a name for the client host */ 2158 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2159 if (lname == NULL) { 2160 error_f("cannot get local ipaddr/name"); 2161 goto out; 2162 } 2163 2164 /* XXX sshbuf_put_stringf? */ 2165 xasprintf(&chost, "%s.", lname); 2166 debug2_f("chost %s", chost); 2167 2168 /* construct data */ 2169 if ((b = sshbuf_new()) == NULL) { 2170 error_f("sshbuf_new failed"); 2171 goto out; 2172 } 2173 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2174 error_fr(r, "sshkey_to_blob"); 2175 goto out; 2176 } 2177 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2178 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2179 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2180 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2181 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2182 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2183 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2184 (r = sshbuf_put_cstring(b, chost)) != 0 || 2185 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2186 error_fr(r, "buffer error"); 2187 goto out; 2188 } 2189 2190 #ifdef DEBUG_PK 2191 sshbuf_dump(b, stderr); 2192 #endif 2193 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2194 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2195 error("sign using hostkey %s %s failed", 2196 sshkey_ssh_name(private), fp); 2197 goto out; 2198 } 2199 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2200 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2201 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2202 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2203 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2204 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2205 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2206 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2207 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2208 (r = sshpkt_send(ssh)) != 0) { 2209 error_fr(r, "packet error"); 2210 goto out; 2211 } 2212 success = 1; 2213 2214 out: 2215 if (sig != NULL) 2216 freezero(sig, siglen); 2217 free(keyblob); 2218 free(lname); 2219 free(fp); 2220 free(chost); 2221 sshkey_free(private); 2222 sshbuf_free(b); 2223 2224 return success; 2225 } 2226 2227 /* find auth method */ 2228 2229 /* 2230 * given auth method name, if configurable options permit this method fill 2231 * in auth_ident field and return true, otherwise return false. 2232 */ 2233 static int 2234 authmethod_is_enabled(Authmethod *method) 2235 { 2236 if (method == NULL) 2237 return 0; 2238 /* return false if options indicate this method is disabled */ 2239 if (method->enabled == NULL || *method->enabled == 0) 2240 return 0; 2241 /* return false if batch mode is enabled but method needs interactive mode */ 2242 if (method->batch_flag != NULL && *method->batch_flag != 0) 2243 return 0; 2244 return 1; 2245 } 2246 2247 static Authmethod * 2248 authmethod_lookup(const char *name) 2249 { 2250 Authmethod *method = NULL; 2251 if (name != NULL) 2252 for (method = authmethods; method->name != NULL; method++) 2253 if (strcmp(name, method->name) == 0) 2254 return method; 2255 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2256 return NULL; 2257 } 2258 2259 /* XXX internal state */ 2260 static Authmethod *current = NULL; 2261 static char *supported = NULL; 2262 static char *preferred = NULL; 2263 2264 /* 2265 * Given the authentication method list sent by the server, return the 2266 * next method we should try. If the server initially sends a nil list, 2267 * use a built-in default list. 2268 */ 2269 static Authmethod * 2270 authmethod_get(char *authlist) 2271 { 2272 char *name = NULL; 2273 u_int next; 2274 2275 /* Use a suitable default if we're passed a nil list. */ 2276 if (authlist == NULL || strlen(authlist) == 0) 2277 authlist = options.preferred_authentications; 2278 2279 if (supported == NULL || strcmp(authlist, supported) != 0) { 2280 debug3("start over, passed a different list %s", authlist); 2281 free(supported); 2282 supported = xstrdup(authlist); 2283 preferred = options.preferred_authentications; 2284 debug3("preferred %s", preferred); 2285 current = NULL; 2286 } else if (current != NULL && authmethod_is_enabled(current)) 2287 return current; 2288 2289 for (;;) { 2290 if ((name = match_list(preferred, supported, &next)) == NULL) { 2291 debug("No more authentication methods to try."); 2292 current = NULL; 2293 return NULL; 2294 } 2295 preferred += next; 2296 debug3("authmethod_lookup %s", name); 2297 debug3("remaining preferred: %s", preferred); 2298 if ((current = authmethod_lookup(name)) != NULL && 2299 authmethod_is_enabled(current)) { 2300 debug3("authmethod_is_enabled %s", name); 2301 debug("Next authentication method: %s", name); 2302 free(name); 2303 return current; 2304 } 2305 free(name); 2306 } 2307 } 2308 2309 static char * 2310 authmethods_get(void) 2311 { 2312 Authmethod *method = NULL; 2313 struct sshbuf *b; 2314 char *list; 2315 int r; 2316 2317 if ((b = sshbuf_new()) == NULL) 2318 fatal_f("sshbuf_new failed"); 2319 for (method = authmethods; method->name != NULL; method++) { 2320 if (authmethod_is_enabled(method)) { 2321 if ((r = sshbuf_putf(b, "%s%s", 2322 sshbuf_len(b) ? "," : "", method->name)) != 0) 2323 fatal_fr(r, "buffer error"); 2324 } 2325 } 2326 if ((list = sshbuf_dup_string(b)) == NULL) 2327 fatal_f("sshbuf_dup_string failed"); 2328 sshbuf_free(b); 2329 return list; 2330 } 2331
Indexes created Fri Mar 06 19:51:54 UTC 2026