1 /* $NetBSD: sshconnect2.c,v 1.40 2021/04/19 14:40:15 christos Exp $ */ 2 /* $OpenBSD: sshconnect2.c,v 1.347 2021/04/03 06:18:41 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2000 Markus Friedl. All rights reserved. 6 * Copyright (c) 2008 Damien Miller. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include "includes.h" 30 __RCSID("$NetBSD: sshconnect2.c,v 1.40 2021/04/19 14:40:15 christos Exp $"); 31 #include <sys/types.h> 32 #include <sys/socket.h> 33 #include <sys/wait.h> 34 #include <sys/queue.h> 35 #include <sys/stat.h> 36 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <limits.h> 40 #include <netdb.h> 41 #include <stdio.h> 42 #include <string.h> 43 #include <stdarg.h> 44 #include <signal.h> 45 #include <pwd.h> 46 #include <unistd.h> 47 #include <vis.h> 48 49 #ifdef KRB5 50 #include <krb5.h> 51 #endif 52 53 #include "xmalloc.h" 54 #include "ssh.h" 55 #include "ssh2.h" 56 #include "sshbuf.h" 57 #include "packet.h" 58 #include "compat.h" 59 #include "cipher.h" 60 #include "sshkey.h" 61 #include "kex.h" 62 #include "myproposal.h" 63 #include "sshconnect.h" 64 #include "authfile.h" 65 #include "dh.h" 66 #include "authfd.h" 67 #include "log.h" 68 #include "misc.h" 69 #include "readconf.h" 70 #include "match.h" 71 #include "dispatch.h" 72 #include "canohost.h" 73 #include "msg.h" 74 #include "pathnames.h" 75 #include "uidswap.h" 76 #include "hostfile.h" 77 #include "ssherr.h" 78 #include "utf8.h" 79 #include "ssh-sk.h" 80 #include "sk-api.h" 81 /* XXX */ 82 const char *auth_get_canonical_hostname(struct ssh *, int); 83 84 #ifdef GSSAPI 85 #include "ssh-gss.h" 86 #endif 87 #ifdef KRB5 88 static int userauth_kerberos(struct ssh *); 89 #endif 90 91 /* import */ 92 extern char *client_version_string; 93 extern char *server_version_string; 94 extern Options options; 95 96 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */ 97 /* if it is set then prevent the switch to the null cipher */ 98 99 extern int tty_flag; 100 101 /* 102 * SSH2 key exchange 103 */ 104 105 static char *xxx_host; 106 static struct sockaddr *xxx_hostaddr; 107 static const struct ssh_conn_info *xxx_conn_info; 108 109 static int 110 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 111 { 112 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 113 xxx_conn_info) == -1) 114 fatal("Host key verification failed."); 115 return 0; 116 } 117 118 /* Returns the first item from a comma-separated algorithm list */ 119 static char * 120 first_alg(const char *algs) 121 { 122 char *ret, *cp; 123 124 ret = xstrdup(algs); 125 if ((cp = strchr(ret, ',')) != NULL) 126 *cp = '\0'; 127 return ret; 128 } 129 130 static char * 131 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 132 const struct ssh_conn_info *cinfo) 133 { 134 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 135 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 136 size_t maxlen; 137 struct hostkeys *hostkeys = NULL; 138 int ktype; 139 u_int i; 140 141 /* Find all hostkeys for this hostname */ 142 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 143 hostkeys = init_hostkeys(); 144 for (i = 0; i < options.num_user_hostfiles; i++) 145 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 146 for (i = 0; i < options.num_system_hostfiles; i++) { 147 load_hostkeys(hostkeys, hostname, 148 options.system_hostfiles[i], 0); 149 } 150 if (options.known_hosts_command != NULL) { 151 load_hostkeys_command(hostkeys, options.known_hosts_command, 152 "ORDER", cinfo, NULL, host); 153 } 154 /* 155 * If a plain public key exists that matches the type of the best 156 * preference HostkeyAlgorithms, then use the whole list as is. 157 * Note that we ignore whether the best preference algorithm is a 158 * certificate type, as sshconnect.c will downgrade certs to 159 * plain keys if necessary. 160 */ 161 best = first_alg(options.hostkeyalgorithms); 162 if (lookup_key_in_hostkeys_by_type(hostkeys, 163 sshkey_type_plain(sshkey_type_from_name(best)), 164 sshkey_ecdsa_nid_from_name(best), NULL)) { 165 debug3_f("have matching best-preference key type %s, " 166 "using HostkeyAlgorithms verbatim", best); 167 ret = xstrdup(options.hostkeyalgorithms); 168 goto out; 169 } 170 171 /* 172 * Otherwise, prefer the host key algorithms that match known keys 173 * while keeping the ordering of HostkeyAlgorithms as much as possible. 174 */ 175 oavail = avail = xstrdup(options.hostkeyalgorithms); 176 maxlen = strlen(avail) + 1; 177 first = xmalloc(maxlen); 178 last = xmalloc(maxlen); 179 *first = *last = '\0'; 180 181 #define ALG_APPEND(to, from) \ 182 do { \ 183 if (*to != '\0') \ 184 strlcat(to, ",", maxlen); \ 185 strlcat(to, from, maxlen); \ 186 } while (0) 187 188 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 189 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 190 fatal_f("unknown alg %s", alg); 191 /* 192 * If we have a @cert-authority marker in known_hosts then 193 * prefer all certificate algorithms. 194 */ 195 if (sshkey_type_is_cert(ktype) && 196 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 197 ALG_APPEND(first, alg); 198 continue; 199 } 200 /* If the key appears in known_hosts then prefer it */ 201 if (lookup_key_in_hostkeys_by_type(hostkeys, 202 sshkey_type_plain(ktype), 203 sshkey_ecdsa_nid_from_name(alg), NULL)) { 204 ALG_APPEND(first, alg); 205 continue; 206 } 207 /* Otherwise, put it last */ 208 ALG_APPEND(last, alg); 209 } 210 #undef ALG_APPEND 211 xasprintf(&ret, "%s%s%s", first, 212 (*first == '\0' || *last == '\0') ? "" : ",", last); 213 if (*first != '\0') 214 debug3_f("prefer hostkeyalgs: %s", first); 215 else 216 debug3_f("no algorithms matched; accept original"); 217 out: 218 free(best); 219 free(first); 220 free(last); 221 free(hostname); 222 free(oavail); 223 free_hostkeys(hostkeys); 224 225 return ret; 226 } 227 228 void 229 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 230 const struct ssh_conn_info *cinfo) 231 { 232 const char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 233 char *s, *all_key; 234 int r, use_known_hosts_order = 0; 235 236 xxx_host = host; 237 xxx_hostaddr = hostaddr; 238 xxx_conn_info = cinfo; 239 240 /* 241 * If the user has not specified HostkeyAlgorithms, or has only 242 * appended or removed algorithms from that list then prefer algorithms 243 * that are in the list that are supported by known_hosts keys. 244 */ 245 if (options.hostkeyalgorithms == NULL || 246 options.hostkeyalgorithms[0] == '-' || 247 options.hostkeyalgorithms[0] == '+') 248 use_known_hosts_order = 1; 249 250 /* Expand or fill in HostkeyAlgorithms */ 251 all_key = sshkey_alg_list(0, 0, 1, ','); 252 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 253 kex_default_pk_alg(), all_key)) != 0) 254 fatal_fr(r, "kex_assemble_namelist"); 255 free(all_key); 256 257 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 258 fatal_f("kex_names_cat"); 259 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, s); 260 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 261 compat_cipher_proposal(ssh, options.ciphers); 262 myproposal[PROPOSAL_ENC_ALGS_STOC] = 263 compat_cipher_proposal(ssh, options.ciphers); 264 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 265 myproposal[PROPOSAL_COMP_ALGS_STOC] = 266 (const char *)compression_alg_list(options.compression); 267 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 268 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 269 if (use_known_hosts_order) { 270 /* Query known_hosts and prefer algorithms that appear there */ 271 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 272 compat_pkalg_proposal(ssh, 273 order_hostkeyalgs(host, hostaddr, port, cinfo)); 274 } else { 275 /* Use specified HostkeyAlgorithms exactly */ 276 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 277 compat_pkalg_proposal(ssh, options.hostkeyalgorithms); 278 } 279 280 if (options.rekey_limit || options.rekey_interval) 281 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 282 options.rekey_interval); 283 284 /* start key exchange */ 285 if ((r = kex_setup(ssh, myproposal)) != 0) 286 fatal_r(r, "kex_setup"); 287 #ifdef WITH_OPENSSL 288 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 289 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 290 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 291 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 292 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 293 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 294 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 295 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 296 #endif 297 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 298 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 299 ssh->kex->verify_host_key=&verify_host_key_callback; 300 301 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 302 303 /* remove ext-info from the KEX proposals for rekeying */ 304 myproposal[PROPOSAL_KEX_ALGS] = 305 compat_kex_proposal(ssh, options.kex_algorithms); 306 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 307 fatal_r(r, "kex_prop2buf"); 308 309 #ifdef DEBUG_KEXDH 310 /* send 1st encrypted/maced/compressed message */ 311 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 312 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 313 (r = sshpkt_send(ssh)) != 0 || 314 (r = ssh_packet_write_wait(ssh)) < 0) 315 fatal_fr(r, "send packet"); 316 #endif 317 } 318 319 /* 320 * Authenticate user 321 */ 322 323 typedef struct cauthctxt Authctxt; 324 typedef struct cauthmethod Authmethod; 325 typedef struct identity Identity; 326 typedef struct idlist Idlist; 327 328 struct identity { 329 TAILQ_ENTRY(identity) next; 330 int agent_fd; /* >=0 if agent supports key */ 331 struct sshkey *key; /* public/private key */ 332 char *filename; /* comment for agent-only keys */ 333 int tried; 334 int isprivate; /* key points to the private key */ 335 int userprovided; 336 }; 337 TAILQ_HEAD(idlist, identity); 338 339 struct cauthctxt { 340 const char *server_user; 341 const char *local_user; 342 const char *host; 343 const char *service; 344 struct cauthmethod *method; 345 sig_atomic_t success; 346 char *authlist; 347 #ifdef GSSAPI 348 /* gssapi */ 349 gss_OID_set gss_supported_mechs; 350 u_int mech_tried; 351 #endif 352 /* pubkey */ 353 struct idlist keys; 354 int agent_fd; 355 /* hostbased */ 356 Sensitive *sensitive; 357 char *oktypes, *ktypes; 358 const char *active_ktype; 359 /* kbd-interactive */ 360 int info_req_seen; 361 int attempt_kbdint; 362 /* password */ 363 int attempt_passwd; 364 /* generic */ 365 void *methoddata; 366 }; 367 368 struct cauthmethod { 369 const char *name; /* string to compare against server's list */ 370 int (*userauth)(struct ssh *ssh); 371 void (*cleanup)(struct ssh *ssh); 372 int *enabled; /* flag in option struct that enables method */ 373 int *batch_flag; /* flag in option struct that disables method */ 374 }; 375 376 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 377 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 378 static int input_userauth_success(int, u_int32_t, struct ssh *); 379 static int input_userauth_failure(int, u_int32_t, struct ssh *); 380 static int input_userauth_banner(int, u_int32_t, struct ssh *); 381 static int input_userauth_error(int, u_int32_t, struct ssh *); 382 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 383 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 384 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 385 386 static int userauth_none(struct ssh *); 387 static int userauth_pubkey(struct ssh *); 388 static int userauth_passwd(struct ssh *); 389 static int userauth_kbdint(struct ssh *); 390 static int userauth_hostbased(struct ssh *); 391 392 #ifdef GSSAPI 393 static int userauth_gssapi(struct ssh *); 394 static void userauth_gssapi_cleanup(struct ssh *); 395 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 396 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 397 static int input_gssapi_error(int, u_int32_t, struct ssh *); 398 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 399 #endif 400 401 void userauth(struct ssh *, char *); 402 403 static void pubkey_cleanup(struct ssh *); 404 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 405 static void pubkey_prepare(Authctxt *); 406 static void pubkey_reset(Authctxt *); 407 static struct sshkey *load_identity_file(Identity *); 408 409 static Authmethod *authmethod_get(char *authlist); 410 static Authmethod *authmethod_lookup(const char *name); 411 static char *authmethods_get(void); 412 413 Authmethod authmethods[] = { 414 #ifdef GSSAPI 415 {"gssapi-with-mic", 416 userauth_gssapi, 417 userauth_gssapi_cleanup, 418 &options.gss_authentication, 419 NULL}, 420 #endif 421 {"hostbased", 422 userauth_hostbased, 423 NULL, 424 &options.hostbased_authentication, 425 NULL}, 426 #if KRB5 427 {"kerberos-2@ssh.com", 428 userauth_kerberos, 429 NULL, 430 &options.kerberos_authentication, 431 NULL}, 432 #endif 433 {"publickey", 434 userauth_pubkey, 435 NULL, 436 &options.pubkey_authentication, 437 NULL}, 438 {"keyboard-interactive", 439 userauth_kbdint, 440 NULL, 441 &options.kbd_interactive_authentication, 442 &options.batch_mode}, 443 {"password", 444 userauth_passwd, 445 NULL, 446 &options.password_authentication, 447 &options.batch_mode}, 448 {"none", 449 userauth_none, 450 NULL, 451 NULL, 452 NULL}, 453 {NULL, NULL, NULL, NULL, NULL} 454 }; 455 456 void 457 ssh_userauth2(struct ssh *ssh, const char *local_user, 458 const char *server_user, char *host, Sensitive *sensitive) 459 { 460 Authctxt authctxt; 461 int r; 462 463 if (options.challenge_response_authentication) 464 options.kbd_interactive_authentication = 1; 465 if (options.preferred_authentications == NULL) 466 options.preferred_authentications = authmethods_get(); 467 468 /* setup authentication context */ 469 memset(&authctxt, 0, sizeof(authctxt)); 470 authctxt.server_user = server_user; 471 authctxt.local_user = local_user; 472 authctxt.host = host; 473 authctxt.service = "ssh-connection"; /* service name */ 474 authctxt.success = 0; 475 authctxt.method = authmethod_lookup("none"); 476 authctxt.authlist = NULL; 477 authctxt.methoddata = NULL; 478 authctxt.sensitive = sensitive; 479 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 480 authctxt.info_req_seen = 0; 481 authctxt.attempt_kbdint = 0; 482 authctxt.attempt_passwd = 0; 483 #if GSSAPI 484 authctxt.gss_supported_mechs = NULL; 485 authctxt.mech_tried = 0; 486 #endif 487 authctxt.agent_fd = -1; 488 pubkey_prepare(&authctxt); 489 if (authctxt.method == NULL) { 490 fatal_f("internal error: cannot send userauth none request"); 491 } 492 493 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 494 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 495 (r = sshpkt_send(ssh)) != 0) 496 fatal_fr(r, "send packet"); 497 498 ssh->authctxt = &authctxt; 499 ssh_dispatch_init(ssh, &input_userauth_error); 500 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 501 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 502 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 503 pubkey_cleanup(ssh); 504 ssh->authctxt = NULL; 505 506 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 507 508 /* if the user wants to use the none cipher do it */ 509 /* post authentication and only if the right conditions are met */ 510 /* both of the NONE commands must be true and there must be no */ 511 /* tty allocated */ 512 if ((options.none_switch == 1) && (options.none_enabled == 1)) 513 { 514 if (tty_flag) /* no null on tty sessions */ 515 { 516 /* requested NONE cipher when in a tty */ 517 debug("Cannot switch to NONE cipher with tty allocated"); 518 fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n"); 519 } 520 } 521 if (!authctxt.success) 522 fatal("Authentication failed."); 523 524 debug("Authentication succeeded (%s).", authctxt.method->name); 525 } 526 527 /* ARGSUSED */ 528 static int 529 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 530 { 531 int r; 532 533 if (ssh_packet_remaining(ssh) > 0) { 534 char *reply; 535 536 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 537 goto out; 538 debug2("service_accept: %s", reply); 539 free(reply); 540 } else { 541 debug2("buggy server: service_accept w/o service"); 542 } 543 if ((r = sshpkt_get_end(ssh)) != 0) 544 goto out; 545 debug("SSH2_MSG_SERVICE_ACCEPT received"); 546 547 /* initial userauth request */ 548 userauth_none(ssh); 549 550 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 551 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 552 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 553 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 554 r = 0; 555 out: 556 return r; 557 } 558 559 /* ARGSUSED */ 560 static int 561 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 562 { 563 return kex_input_ext_info(type, seqnr, ssh); 564 } 565 566 void 567 userauth(struct ssh *ssh, char *authlist) 568 { 569 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 570 571 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 572 authctxt->method->cleanup(ssh); 573 574 free(authctxt->methoddata); 575 authctxt->methoddata = NULL; 576 if (authlist == NULL) { 577 authlist = authctxt->authlist; 578 } else { 579 free(authctxt->authlist); 580 authctxt->authlist = authlist; 581 } 582 for (;;) { 583 Authmethod *method = authmethod_get(authlist); 584 if (method == NULL) 585 fatal("%s@%s: Permission denied (%s).", 586 authctxt->server_user, authctxt->host, authlist); 587 authctxt->method = method; 588 589 /* reset the per method handler */ 590 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 591 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 592 593 /* and try new method */ 594 if (method->userauth(ssh) != 0) { 595 debug2("we sent a %s packet, wait for reply", method->name); 596 break; 597 } else { 598 debug2("we did not send a packet, disable method"); 599 method->enabled = NULL; 600 } 601 } 602 } 603 604 /* ARGSUSED */ 605 static int 606 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 607 { 608 fatal_f("bad message during authentication: type %d", type); 609 return 0; 610 } 611 612 /* ARGSUSED */ 613 static int 614 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 615 { 616 char *msg = NULL; 617 size_t len; 618 int r; 619 620 debug3_f("entering"); 621 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 622 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 623 goto out; 624 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 625 fmprintf(stderr, "%s", msg); 626 r = 0; 627 out: 628 free(msg); 629 return r; 630 } 631 632 /* ARGSUSED */ 633 static int 634 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 635 { 636 Authctxt *authctxt = ssh->authctxt; 637 638 if (authctxt == NULL) 639 fatal_f("no authentication context"); 640 free(authctxt->authlist); 641 authctxt->authlist = NULL; 642 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 643 authctxt->method->cleanup(ssh); 644 free(authctxt->methoddata); 645 authctxt->methoddata = NULL; 646 authctxt->success = 1; /* break out */ 647 return 0; 648 } 649 650 #if 0 651 static int 652 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 653 { 654 Authctxt *authctxt = ssh->authctxt; 655 656 if (authctxt == NULL) 657 fatal_f("no authentication context"); 658 659 fatal("Unexpected authentication success during %s.", 660 authctxt->method->name); 661 return 0; 662 } 663 #endif 664 665 /* ARGSUSED */ 666 static int 667 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 668 { 669 Authctxt *authctxt = ssh->authctxt; 670 char *authlist = NULL; 671 u_char partial; 672 673 if (authctxt == NULL) 674 fatal("input_userauth_failure: no authentication context"); 675 676 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 677 sshpkt_get_u8(ssh, &partial) != 0 || 678 sshpkt_get_end(ssh) != 0) 679 goto out; 680 681 if (partial != 0) { 682 verbose("Authenticated with partial success."); 683 /* reset state */ 684 pubkey_reset(authctxt); 685 } 686 debug("Authentications that can continue: %s", authlist); 687 688 userauth(ssh, authlist); 689 authlist = NULL; 690 out: 691 free(authlist); 692 return 0; 693 } 694 695 /* 696 * Format an identity for logging including filename, key type, fingerprint 697 * and location (agent, etc.). Caller must free. 698 */ 699 static char * 700 format_identity(Identity *id) 701 { 702 char *fp = NULL, *ret = NULL; 703 const char *note = ""; 704 705 if (id->key != NULL) { 706 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 707 SSH_FP_DEFAULT); 708 } 709 if (id->key) { 710 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 711 note = " token"; 712 else if (sshkey_is_sk(id->key)) 713 note = " authenticator"; 714 } 715 xasprintf(&ret, "%s %s%s%s%s%s%s", 716 id->filename, 717 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 718 fp ? fp : "", 719 id->userprovided ? " explicit" : "", note, 720 id->agent_fd != -1 ? " agent" : ""); 721 free(fp); 722 return ret; 723 } 724 725 /* ARGSUSED */ 726 static int 727 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 728 { 729 Authctxt *authctxt = ssh->authctxt; 730 struct sshkey *key = NULL; 731 Identity *id = NULL; 732 int pktype, found = 0, sent = 0; 733 size_t blen; 734 char *pkalg = NULL, *fp = NULL, *ident = NULL; 735 u_char *pkblob = NULL; 736 int r; 737 738 if (authctxt == NULL) 739 fatal("input_userauth_pk_ok: no authentication context"); 740 741 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 742 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 743 (r = sshpkt_get_end(ssh)) != 0) 744 goto done; 745 746 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 747 debug_f("server sent unknown pkalg %s", pkalg); 748 goto done; 749 } 750 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 751 debug_r(r, "no key from blob. pkalg %s", pkalg); 752 goto done; 753 } 754 if (key->type != pktype) { 755 error("input_userauth_pk_ok: type mismatch " 756 "for decoded key (received %d, expected %d)", 757 key->type, pktype); 758 goto done; 759 } 760 761 /* 762 * search keys in the reverse order, because last candidate has been 763 * moved to the end of the queue. this also avoids confusion by 764 * duplicate keys 765 */ 766 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 767 if (sshkey_equal(key, id->key)) { 768 found = 1; 769 break; 770 } 771 } 772 if (!found || id == NULL) { 773 fp = sshkey_fingerprint(key, options.fingerprint_hash, 774 SSH_FP_DEFAULT); 775 error_f("server replied with unknown key: %s %s", 776 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 777 goto done; 778 } 779 ident = format_identity(id); 780 debug("Server accepts key: %s", ident); 781 sent = sign_and_send_pubkey(ssh, id); 782 r = 0; 783 done: 784 sshkey_free(key); 785 free(ident); 786 free(fp); 787 free(pkalg); 788 free(pkblob); 789 790 /* try another method if we did not send a packet */ 791 if (r == 0 && sent == 0) 792 userauth(ssh, NULL); 793 return r; 794 } 795 796 #ifdef GSSAPI 797 static int 798 userauth_gssapi(struct ssh *ssh) 799 { 800 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 801 Gssctxt *gssctxt = NULL; 802 OM_uint32 min; 803 int r, ok = 0; 804 gss_OID mech = NULL; 805 806 /* Try one GSSAPI method at a time, rather than sending them all at 807 * once. */ 808 809 if (authctxt->gss_supported_mechs == NULL) 810 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 811 812 /* Check to see whether the mechanism is usable before we offer it */ 813 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 814 !ok) { 815 mech = &authctxt->gss_supported_mechs-> 816 elements[authctxt->mech_tried]; 817 /* My DER encoding requires length<128 */ 818 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 819 mech, authctxt->host)) { 820 ok = 1; /* Mechanism works */ 821 } else { 822 authctxt->mech_tried++; 823 } 824 } 825 826 if (!ok || mech == NULL) 827 return 0; 828 829 authctxt->methoddata=(void *)gssctxt; 830 831 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 832 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 833 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 834 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 835 (r = sshpkt_put_u32(ssh, 1)) != 0 || 836 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 837 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 838 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 839 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 840 (r = sshpkt_send(ssh)) != 0) 841 fatal_fr(r, "send packet"); 842 843 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 844 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 845 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 846 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 847 848 authctxt->mech_tried++; /* Move along to next candidate */ 849 850 return 1; 851 } 852 853 static void 854 userauth_gssapi_cleanup(struct ssh *ssh) 855 { 856 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 857 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 858 859 ssh_gssapi_delete_ctx(&gssctxt); 860 authctxt->methoddata = NULL; 861 862 free(authctxt->gss_supported_mechs); 863 authctxt->gss_supported_mechs = NULL; 864 } 865 866 static OM_uint32 867 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 868 { 869 Authctxt *authctxt = ssh->authctxt; 870 Gssctxt *gssctxt = authctxt->methoddata; 871 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 872 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 873 gss_buffer_desc gssbuf; 874 OM_uint32 status, ms, flags; 875 int r; 876 877 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 878 recv_tok, &send_tok, &flags); 879 880 if (send_tok.length > 0) { 881 u_char type = GSS_ERROR(status) ? 882 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 883 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 884 885 if ((r = sshpkt_start(ssh, type)) != 0 || 886 (r = sshpkt_put_string(ssh, send_tok.value, 887 send_tok.length)) != 0 || 888 (r = sshpkt_send(ssh)) != 0) 889 fatal_fr(r, "send %u packet", type); 890 891 gss_release_buffer(&ms, &send_tok); 892 } 893 894 if (status == GSS_S_COMPLETE) { 895 /* send either complete or MIC, depending on mechanism */ 896 if (!(flags & GSS_C_INTEG_FLAG)) { 897 if ((r = sshpkt_start(ssh, 898 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 899 (r = sshpkt_send(ssh)) != 0) 900 fatal_fr(r, "send completion"); 901 } else { 902 struct sshbuf *b; 903 904 if ((b = sshbuf_new()) == NULL) 905 fatal_f("sshbuf_new failed"); 906 ssh_gssapi_buildmic(b, authctxt->server_user, 907 authctxt->service, "gssapi-with-mic", 908 ssh->kex->session_id); 909 910 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 911 fatal_f("sshbuf_mutable_ptr failed"); 912 gssbuf.length = sshbuf_len(b); 913 914 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 915 916 if (!GSS_ERROR(status)) { 917 if ((r = sshpkt_start(ssh, 918 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 919 (r = sshpkt_put_string(ssh, mic.value, 920 mic.length)) != 0 || 921 (r = sshpkt_send(ssh)) != 0) 922 fatal_fr(r, "send MIC"); 923 } 924 925 sshbuf_free(b); 926 gss_release_buffer(&ms, &mic); 927 } 928 } 929 930 return status; 931 } 932 933 /* ARGSUSED */ 934 static int 935 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 936 { 937 Authctxt *authctxt = ssh->authctxt; 938 Gssctxt *gssctxt; 939 size_t oidlen; 940 u_char *oidv = NULL; 941 int r; 942 943 if (authctxt == NULL) 944 fatal("input_gssapi_response: no authentication context"); 945 gssctxt = authctxt->methoddata; 946 947 /* Setup our OID */ 948 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 949 goto done; 950 951 if (oidlen <= 2 || 952 oidv[0] != SSH_GSS_OIDTYPE || 953 oidv[1] != oidlen - 2) { 954 debug("Badly encoded mechanism OID received"); 955 userauth(ssh, NULL); 956 goto ok; 957 } 958 959 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 960 fatal("Server returned different OID than expected"); 961 962 if ((r = sshpkt_get_end(ssh)) != 0) 963 goto done; 964 965 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 966 /* Start again with next method on list */ 967 debug("Trying to start again"); 968 userauth(ssh, NULL); 969 goto ok; 970 } 971 ok: 972 r = 0; 973 done: 974 free(oidv); 975 return r; 976 } 977 978 /* ARGSUSED */ 979 static int 980 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 981 { 982 Authctxt *authctxt = ssh->authctxt; 983 gss_buffer_desc recv_tok; 984 u_char *p = NULL; 985 size_t len; 986 OM_uint32 status; 987 int r; 988 989 if (authctxt == NULL) 990 fatal("input_gssapi_response: no authentication context"); 991 992 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 993 (r = sshpkt_get_end(ssh)) != 0) 994 goto out; 995 996 recv_tok.value = p; 997 recv_tok.length = len; 998 status = process_gssapi_token(ssh, &recv_tok); 999 1000 /* Start again with the next method in the list */ 1001 if (GSS_ERROR(status)) { 1002 userauth(ssh, NULL); 1003 /* ok */ 1004 } 1005 r = 0; 1006 out: 1007 free(p); 1008 return r; 1009 } 1010 1011 /* ARGSUSED */ 1012 static int 1013 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 1014 { 1015 Authctxt *authctxt = ssh->authctxt; 1016 Gssctxt *gssctxt; 1017 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 1018 gss_buffer_desc recv_tok; 1019 OM_uint32 ms; 1020 u_char *p = NULL; 1021 size_t len; 1022 int r; 1023 1024 if (authctxt == NULL) 1025 fatal("input_gssapi_response: no authentication context"); 1026 gssctxt = authctxt->methoddata; 1027 1028 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1029 (r = sshpkt_get_end(ssh)) != 0) { 1030 free(p); 1031 return r; 1032 } 1033 1034 /* Stick it into GSSAPI and see what it says */ 1035 recv_tok.value = p; 1036 recv_tok.length = len; 1037 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1038 &recv_tok, &send_tok, NULL); 1039 free(p); 1040 gss_release_buffer(&ms, &send_tok); 1041 1042 /* Server will be returning a failed packet after this one */ 1043 return 0; 1044 } 1045 1046 /* ARGSUSED */ 1047 static int 1048 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1049 { 1050 char *msg = NULL; 1051 char *lang = NULL; 1052 int r; 1053 1054 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1055 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1056 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1057 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1058 goto out; 1059 r = sshpkt_get_end(ssh); 1060 debug("Server GSSAPI Error:\n%s", msg); 1061 out: 1062 free(msg); 1063 free(lang); 1064 return r; 1065 } 1066 #endif /* GSSAPI */ 1067 1068 static int 1069 userauth_none(struct ssh *ssh) 1070 { 1071 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1072 int r; 1073 1074 /* initial userauth request */ 1075 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1076 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1077 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1078 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1079 (r = sshpkt_send(ssh)) != 0) 1080 fatal_fr(r, "send packet"); 1081 return 1; 1082 } 1083 1084 static int 1085 userauth_passwd(struct ssh *ssh) 1086 { 1087 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1088 char *password, *prompt = NULL; 1089 const char *host = options.host_key_alias ? options.host_key_alias : 1090 authctxt->host; 1091 int r; 1092 1093 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1094 return 0; 1095 1096 if (authctxt->attempt_passwd != 1) 1097 error("Permission denied, please try again."); 1098 1099 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1100 password = read_passphrase(prompt, 0); 1101 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1102 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1103 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1104 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1105 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1106 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1107 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1108 (r = sshpkt_send(ssh)) != 0) 1109 fatal_fr(r, "send packet"); 1110 1111 free(prompt); 1112 if (password != NULL) 1113 freezero(password, strlen(password)); 1114 1115 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1116 &input_userauth_passwd_changereq); 1117 1118 return 1; 1119 } 1120 1121 /* 1122 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1123 */ 1124 /* ARGSUSED */ 1125 static int 1126 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1127 { 1128 Authctxt *authctxt = ssh->authctxt; 1129 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1130 char prompt[256]; 1131 const char *host; 1132 int r; 1133 1134 debug2("input_userauth_passwd_changereq"); 1135 1136 if (authctxt == NULL) 1137 fatal("input_userauth_passwd_changereq: " 1138 "no authentication context"); 1139 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1140 1141 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1142 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1143 goto out; 1144 if (strlen(info) > 0) 1145 logit("%s", info); 1146 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1147 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1148 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1149 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1150 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1151 goto out; 1152 1153 snprintf(prompt, sizeof(prompt), 1154 "Enter %.30s@%.128s's old password: ", 1155 authctxt->server_user, host); 1156 password = read_passphrase(prompt, 0); 1157 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1158 goto out; 1159 1160 freezero(password, strlen(password)); 1161 password = NULL; 1162 while (password == NULL) { 1163 snprintf(prompt, sizeof(prompt), 1164 "Enter %.30s@%.128s's new password: ", 1165 authctxt->server_user, host); 1166 password = read_passphrase(prompt, RP_ALLOW_EOF); 1167 if (password == NULL) { 1168 /* bail out */ 1169 r = 0; 1170 goto out; 1171 } 1172 snprintf(prompt, sizeof(prompt), 1173 "Retype %.30s@%.128s's new password: ", 1174 authctxt->server_user, host); 1175 retype = read_passphrase(prompt, 0); 1176 if (strcmp(password, retype) != 0) { 1177 freezero(password, strlen(password)); 1178 logit("Mismatch; try again, EOF to quit."); 1179 password = NULL; 1180 } 1181 freezero(retype, strlen(retype)); 1182 } 1183 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1184 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1185 (r = sshpkt_send(ssh)) != 0) 1186 goto out; 1187 1188 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1189 &input_userauth_passwd_changereq); 1190 r = 0; 1191 out: 1192 if (password) 1193 freezero(password, strlen(password)); 1194 free(info); 1195 free(lang); 1196 return r; 1197 } 1198 1199 /* 1200 * Select an algorithm for publickey signatures. 1201 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1202 * 1203 * Call with ssh==NULL to ignore server-sig-algs extension list and 1204 * only attempt with the key's base signature type. 1205 */ 1206 static char * 1207 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1208 { 1209 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1210 1211 /* 1212 * The signature algorithm will only differ from the key algorithm 1213 * for RSA keys/certs and when the server advertises support for 1214 * newer (SHA2) algorithms. 1215 */ 1216 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1217 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1218 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1219 /* Filter base key signature alg against our configuration */ 1220 return match_list(sshkey_ssh_name(key), 1221 options.pubkey_accepted_algos, NULL); 1222 } 1223 1224 /* 1225 * For RSA keys/certs, since these might have a different sig type: 1226 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1227 * that also appears in the supported signature algorithms list from 1228 * the server. 1229 */ 1230 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1231 while ((cp = strsep(&allowed, ",")) != NULL) { 1232 if (sshkey_type_from_name(cp) != key->type) 1233 continue; 1234 tmp = match_list(sshkey_sigalg_by_name(cp), 1235 ssh->kex->server_sig_algs, NULL); 1236 if (tmp != NULL) 1237 alg = xstrdup(cp); 1238 free(tmp); 1239 if (alg != NULL) 1240 break; 1241 } 1242 free(oallowed); 1243 return alg; 1244 } 1245 1246 static int 1247 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1248 const u_char *data, size_t datalen, u_int compat, const char *alg) 1249 { 1250 struct sshkey *sign_key = NULL, *prv = NULL; 1251 int retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1252 struct notifier_ctx *notifier = NULL; 1253 char *fp = NULL, *pin = NULL, *prompt = NULL; 1254 1255 *sigp = NULL; 1256 *lenp = 0; 1257 1258 /* The agent supports this key. */ 1259 if (id->key != NULL && id->agent_fd != -1) { 1260 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1261 data, datalen, alg, compat); 1262 } 1263 1264 /* 1265 * We have already loaded the private key or the private key is 1266 * stored in external hardware. 1267 */ 1268 if (id->key != NULL && 1269 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1270 sign_key = id->key; 1271 } else { 1272 /* Load the private key from the file. */ 1273 if ((prv = load_identity_file(id)) == NULL) 1274 return SSH_ERR_KEY_NOT_FOUND; 1275 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1276 error_f("private key %s contents do not match public", 1277 id->filename); 1278 r = SSH_ERR_KEY_NOT_FOUND; 1279 goto out; 1280 } 1281 sign_key = prv; 1282 if (sshkey_is_sk(sign_key)) { 1283 if ((sign_key->sk_flags & 1284 SSH_SK_USER_VERIFICATION_REQD)) { 1285 retry_pin: 1286 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1287 sshkey_type(sign_key), id->filename); 1288 pin = read_passphrase(prompt, 0); 1289 } 1290 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1291 /* XXX should batch mode just skip these? */ 1292 if ((fp = sshkey_fingerprint(sign_key, 1293 options.fingerprint_hash, 1294 SSH_FP_DEFAULT)) == NULL) 1295 fatal_f("fingerprint failed"); 1296 notifier = notify_start(options.batch_mode, 1297 "Confirm user presence for key %s %s", 1298 sshkey_type(sign_key), fp); 1299 free(fp); 1300 } 1301 } 1302 } 1303 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1304 alg, options.sk_provider, pin, compat)) != 0) { 1305 debug_fr(r, "sshkey_sign"); 1306 if (pin == NULL && !retried && sshkey_is_sk(sign_key) && 1307 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1308 notify_complete(notifier, NULL); 1309 notifier = NULL; 1310 retried = 1; 1311 goto retry_pin; 1312 } 1313 goto out; 1314 } 1315 1316 /* 1317 * PKCS#11 tokens may not support all signature algorithms, 1318 * so check what we get back. 1319 */ 1320 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1321 debug_fr(r, "sshkey_check_sigtype"); 1322 goto out; 1323 } 1324 /* success */ 1325 r = 0; 1326 out: 1327 free(prompt); 1328 if (pin != NULL) 1329 freezero(pin, strlen(pin)); 1330 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1331 sshkey_free(prv); 1332 return r; 1333 } 1334 1335 static int 1336 id_filename_matches(Identity *id, Identity *private_id) 1337 { 1338 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1339 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1340 size_t i, slen; 1341 1342 if (strcmp(id->filename, private_id->filename) == 0) 1343 return 1; 1344 for (i = 0; suffixes[i]; i++) { 1345 slen = strlen(suffixes[i]); 1346 if (len > slen && plen == len - slen && 1347 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1348 memcmp(id->filename, private_id->filename, plen) == 0) 1349 return 1; 1350 } 1351 return 0; 1352 } 1353 1354 static int 1355 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1356 { 1357 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1358 struct sshbuf *b = NULL; 1359 Identity *private_id, *sign_id = NULL; 1360 u_char *signature = NULL; 1361 size_t slen = 0, skip = 0; 1362 int r, fallback_sigtype, sent = 0; 1363 char *alg = NULL, *fp = NULL; 1364 const char *loc = ""; 1365 1366 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1367 SSH_FP_DEFAULT)) == NULL) 1368 return 0; 1369 1370 debug3_f("%s %s", sshkey_type(id->key), fp); 1371 1372 /* 1373 * If the key is an certificate, try to find a matching private key 1374 * and use it to complete the signature. 1375 * If no such private key exists, fall back to trying the certificate 1376 * key itself in case it has a private half already loaded. 1377 * This will try to set sign_id to the private key that will perform 1378 * the signature. 1379 */ 1380 if (sshkey_is_cert(id->key)) { 1381 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1382 if (sshkey_equal_public(id->key, private_id->key) && 1383 id->key->type != private_id->key->type) { 1384 sign_id = private_id; 1385 break; 1386 } 1387 } 1388 /* 1389 * Exact key matches are preferred, but also allow 1390 * filename matches for non-PKCS#11/agent keys that 1391 * didn't load public keys. This supports the case 1392 * of keeping just a private key file and public 1393 * certificate on disk. 1394 */ 1395 if (sign_id == NULL && 1396 !id->isprivate && id->agent_fd == -1 && 1397 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1398 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1399 if (private_id->key == NULL && 1400 id_filename_matches(id, private_id)) { 1401 sign_id = private_id; 1402 break; 1403 } 1404 } 1405 } 1406 if (sign_id != NULL) { 1407 debug2_f("using private key \"%s\"%s for " 1408 "certificate", id->filename, 1409 id->agent_fd != -1 ? " from agent" : ""); 1410 } else { 1411 debug_f("no separate private key for certificate " 1412 "\"%s\"", id->filename); 1413 } 1414 } 1415 1416 /* 1417 * If the above didn't select another identity to do the signing 1418 * then default to the one we started with. 1419 */ 1420 if (sign_id == NULL) 1421 sign_id = id; 1422 1423 /* assemble and sign data */ 1424 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1425 free(alg); 1426 slen = 0; 1427 signature = NULL; 1428 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1429 id->key)) == NULL) { 1430 error_f("no mutual signature supported"); 1431 goto out; 1432 } 1433 debug3_f("signing using %s %s", alg, fp); 1434 1435 sshbuf_free(b); 1436 if ((b = sshbuf_new()) == NULL) 1437 fatal_f("sshbuf_new failed"); 1438 if (ssh->compat & SSH_OLD_SESSIONID) { 1439 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1440 fatal_fr(r, "sshbuf_putb"); 1441 } else { 1442 if ((r = sshbuf_put_stringb(b, 1443 ssh->kex->session_id)) != 0) 1444 fatal_fr(r, "sshbuf_put_stringb"); 1445 } 1446 skip = sshbuf_len(b); 1447 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1448 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1449 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1450 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1451 (r = sshbuf_put_u8(b, 1)) != 0 || 1452 (r = sshbuf_put_cstring(b, alg)) != 0 || 1453 (r = sshkey_puts(id->key, b)) != 0) { 1454 fatal_fr(r, "assemble signed data"); 1455 } 1456 1457 /* generate signature */ 1458 r = identity_sign(sign_id, &signature, &slen, 1459 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1460 if (r == 0) 1461 break; 1462 else if (r == SSH_ERR_KEY_NOT_FOUND) 1463 goto out; /* soft failure */ 1464 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1465 !fallback_sigtype) { 1466 if (sign_id->agent_fd != -1) 1467 loc = "agent "; 1468 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1469 loc = "token "; 1470 logit("%skey %s %s returned incorrect signature type", 1471 loc, sshkey_type(id->key), fp); 1472 continue; 1473 } 1474 error_fr(r, "signing failed for %s \"%s\"%s", 1475 sshkey_type(sign_id->key), sign_id->filename, 1476 id->agent_fd != -1 ? " from agent" : ""); 1477 goto out; 1478 } 1479 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1480 fatal_f("no signature"); 1481 1482 /* append signature */ 1483 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1484 fatal_fr(r, "append signature"); 1485 1486 #ifdef DEBUG_PK 1487 sshbuf_dump(b, stderr); 1488 #endif 1489 /* skip session id and packet type */ 1490 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1491 fatal_fr(r, "consume"); 1492 1493 /* put remaining data from buffer into packet */ 1494 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1495 (r = sshpkt_putb(ssh, b)) != 0 || 1496 (r = sshpkt_send(ssh)) != 0) 1497 fatal_fr(r, "enqueue request"); 1498 1499 /* success */ 1500 sent = 1; 1501 1502 out: 1503 free(fp); 1504 free(alg); 1505 sshbuf_free(b); 1506 freezero(signature, slen); 1507 return sent; 1508 } 1509 1510 static int 1511 send_pubkey_test(struct ssh *ssh, Identity *id) 1512 { 1513 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1514 u_char *blob = NULL; 1515 char *alg = NULL; 1516 size_t bloblen; 1517 u_int have_sig = 0; 1518 int sent = 0, r; 1519 1520 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1521 debug_f("no mutual signature algorithm"); 1522 goto out; 1523 } 1524 1525 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1526 /* we cannot handle this key */ 1527 debug3_f("cannot handle key"); 1528 goto out; 1529 } 1530 /* register callback for USERAUTH_PK_OK message */ 1531 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1532 1533 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1534 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1535 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1536 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1537 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1538 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1539 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1540 (r = sshpkt_send(ssh)) != 0) 1541 fatal_fr(r, "send packet"); 1542 sent = 1; 1543 1544 out: 1545 free(alg); 1546 free(blob); 1547 return sent; 1548 } 1549 1550 static struct sshkey * 1551 load_identity_file(Identity *id) 1552 { 1553 struct sshkey *private = NULL; 1554 char prompt[300], *passphrase, *comment; 1555 int r, quit = 0, i; 1556 struct stat st; 1557 1558 if (stat(id->filename, &st) == -1) { 1559 do_log2(id->userprovided ? 1560 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1561 "no such identity: %s: %s", id->filename, strerror(errno)); 1562 return NULL; 1563 } 1564 snprintf(prompt, sizeof prompt, 1565 "Enter passphrase for key '%.100s': ", id->filename); 1566 for (i = 0; i <= options.number_of_password_prompts; i++) { 1567 if (i == 0) 1568 passphrase = xstrdup(""); 1569 else { 1570 passphrase = read_passphrase(prompt, 0); 1571 if (*passphrase == '\0') { 1572 debug2("no passphrase given, try next key"); 1573 free(passphrase); 1574 break; 1575 } 1576 } 1577 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1578 passphrase, &private, &comment))) { 1579 case 0: 1580 break; 1581 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1582 if (options.batch_mode) { 1583 quit = 1; 1584 break; 1585 } 1586 if (i != 0) 1587 debug2("bad passphrase given, try again..."); 1588 break; 1589 case SSH_ERR_SYSTEM_ERROR: 1590 if (errno == ENOENT) { 1591 debug2_r(r, "Load key \"%s\"", id->filename); 1592 quit = 1; 1593 break; 1594 } 1595 /* FALLTHROUGH */ 1596 default: 1597 error_r(r, "Load key \"%s\"", id->filename); 1598 quit = 1; 1599 break; 1600 } 1601 if (private != NULL && sshkey_is_sk(private) && 1602 options.sk_provider == NULL) { 1603 debug("key \"%s\" is an authenticator-hosted key, " 1604 "but no provider specified", id->filename); 1605 sshkey_free(private); 1606 private = NULL; 1607 quit = 1; 1608 } 1609 if (!quit && private != NULL && id->agent_fd == -1 && 1610 !(id->key && id->isprivate)) 1611 maybe_add_key_to_agent(id->filename, private, comment, 1612 passphrase); 1613 if (i > 0) 1614 freezero(passphrase, strlen(passphrase)); 1615 free(comment); 1616 if (private != NULL || quit) 1617 break; 1618 } 1619 return private; 1620 } 1621 1622 static int 1623 key_type_allowed_by_config(struct sshkey *key) 1624 { 1625 if (match_pattern_list(sshkey_ssh_name(key), 1626 options.pubkey_accepted_algos, 0) == 1) 1627 return 1; 1628 1629 /* RSA keys/certs might be allowed by alternate signature types */ 1630 switch (key->type) { 1631 case KEY_RSA: 1632 if (match_pattern_list("rsa-sha2-512", 1633 options.pubkey_accepted_algos, 0) == 1) 1634 return 1; 1635 if (match_pattern_list("rsa-sha2-256", 1636 options.pubkey_accepted_algos, 0) == 1) 1637 return 1; 1638 break; 1639 case KEY_RSA_CERT: 1640 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1641 options.pubkey_accepted_algos, 0) == 1) 1642 return 1; 1643 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1644 options.pubkey_accepted_algos, 0) == 1) 1645 return 1; 1646 break; 1647 } 1648 return 0; 1649 } 1650 1651 1652 /* 1653 * try keys in the following order: 1654 * 1. certificates listed in the config file 1655 * 2. other input certificates 1656 * 3. agent keys that are found in the config file 1657 * 4. other agent keys 1658 * 5. keys that are only listed in the config file 1659 */ 1660 static void 1661 pubkey_prepare(Authctxt *authctxt) 1662 { 1663 struct identity *id, *id2, *tmp; 1664 struct idlist agent, files, *preferred; 1665 struct sshkey *key; 1666 int agent_fd = -1, i, r, found; 1667 size_t j; 1668 struct ssh_identitylist *idlist; 1669 char *ident; 1670 1671 TAILQ_INIT(&agent); /* keys from the agent */ 1672 TAILQ_INIT(&files); /* keys from the config file */ 1673 preferred = &authctxt->keys; 1674 TAILQ_INIT(preferred); /* preferred order of keys */ 1675 1676 /* list of keys stored in the filesystem and PKCS#11 */ 1677 for (i = 0; i < options.num_identity_files; i++) { 1678 key = options.identity_keys[i]; 1679 if (key && key->cert && 1680 key->cert->type != SSH2_CERT_TYPE_USER) { 1681 debug_f("ignoring certificate %s: not a user " 1682 "certificate", options.identity_files[i]); 1683 continue; 1684 } 1685 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1686 debug_f("ignoring authenticator-hosted key %s as no " 1687 "SecurityKeyProvider has been specified", 1688 options.identity_files[i]); 1689 continue; 1690 } 1691 options.identity_keys[i] = NULL; 1692 id = xcalloc(1, sizeof(*id)); 1693 id->agent_fd = -1; 1694 id->key = key; 1695 id->filename = xstrdup(options.identity_files[i]); 1696 id->userprovided = options.identity_file_userprovided[i]; 1697 TAILQ_INSERT_TAIL(&files, id, next); 1698 } 1699 /* list of certificates specified by user */ 1700 for (i = 0; i < options.num_certificate_files; i++) { 1701 key = options.certificates[i]; 1702 if (!sshkey_is_cert(key) || key->cert == NULL || 1703 key->cert->type != SSH2_CERT_TYPE_USER) { 1704 debug_f("ignoring certificate %s: not a user " 1705 "certificate", options.identity_files[i]); 1706 continue; 1707 } 1708 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1709 debug_f("ignoring authenticator-hosted key " 1710 "certificate %s as no " 1711 "SecurityKeyProvider has been specified", 1712 options.identity_files[i]); 1713 continue; 1714 } 1715 id = xcalloc(1, sizeof(*id)); 1716 id->agent_fd = -1; 1717 id->key = key; 1718 id->filename = xstrdup(options.certificate_files[i]); 1719 id->userprovided = options.certificate_file_userprovided[i]; 1720 TAILQ_INSERT_TAIL(preferred, id, next); 1721 } 1722 /* list of keys supported by the agent */ 1723 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1724 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1725 debug_fr(r, "ssh_get_authentication_socket"); 1726 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1727 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1728 debug_fr(r, "ssh_fetch_identitylist"); 1729 close(agent_fd); 1730 } else { 1731 for (j = 0; j < idlist->nkeys; j++) { 1732 found = 0; 1733 TAILQ_FOREACH(id, &files, next) { 1734 /* 1735 * agent keys from the config file are 1736 * preferred 1737 */ 1738 if (sshkey_equal(idlist->keys[j], id->key)) { 1739 TAILQ_REMOVE(&files, id, next); 1740 TAILQ_INSERT_TAIL(preferred, id, next); 1741 id->agent_fd = agent_fd; 1742 found = 1; 1743 break; 1744 } 1745 } 1746 if (!found && !options.identities_only) { 1747 id = xcalloc(1, sizeof(*id)); 1748 /* XXX "steals" key/comment from idlist */ 1749 id->key = idlist->keys[j]; 1750 id->filename = idlist->comments[j]; 1751 idlist->keys[j] = NULL; 1752 idlist->comments[j] = NULL; 1753 id->agent_fd = agent_fd; 1754 TAILQ_INSERT_TAIL(&agent, id, next); 1755 } 1756 } 1757 ssh_free_identitylist(idlist); 1758 /* append remaining agent keys */ 1759 TAILQ_CONCAT(preferred, &agent, next); 1760 authctxt->agent_fd = agent_fd; 1761 } 1762 /* Prefer PKCS11 keys that are explicitly listed */ 1763 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1764 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1765 continue; 1766 found = 0; 1767 TAILQ_FOREACH(id2, &files, next) { 1768 if (id2->key == NULL || 1769 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1770 continue; 1771 if (sshkey_equal(id->key, id2->key)) { 1772 TAILQ_REMOVE(&files, id, next); 1773 TAILQ_INSERT_TAIL(preferred, id, next); 1774 found = 1; 1775 break; 1776 } 1777 } 1778 /* If IdentitiesOnly set and key not found then don't use it */ 1779 if (!found && options.identities_only) { 1780 TAILQ_REMOVE(&files, id, next); 1781 freezero(id, sizeof(*id)); 1782 } 1783 } 1784 /* append remaining keys from the config file */ 1785 TAILQ_CONCAT(preferred, &files, next); 1786 /* finally, filter by PubkeyAcceptedAlgorithms */ 1787 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1788 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1789 debug("Skipping %s key %s - " 1790 "corresponding algo not in PubkeyAcceptedAlgorithms", 1791 sshkey_ssh_name(id->key), id->filename); 1792 TAILQ_REMOVE(preferred, id, next); 1793 sshkey_free(id->key); 1794 free(id->filename); 1795 memset(id, 0, sizeof(*id)); 1796 continue; 1797 } 1798 } 1799 /* List the keys we plan on using */ 1800 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1801 ident = format_identity(id); 1802 debug("Will attempt key: %s", ident); 1803 free(ident); 1804 } 1805 debug2_f("done"); 1806 } 1807 1808 static void 1809 pubkey_cleanup(struct ssh *ssh) 1810 { 1811 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1812 Identity *id; 1813 1814 if (authctxt->agent_fd != -1) { 1815 ssh_close_authentication_socket(authctxt->agent_fd); 1816 authctxt->agent_fd = -1; 1817 } 1818 for (id = TAILQ_FIRST(&authctxt->keys); id; 1819 id = TAILQ_FIRST(&authctxt->keys)) { 1820 TAILQ_REMOVE(&authctxt->keys, id, next); 1821 sshkey_free(id->key); 1822 free(id->filename); 1823 free(id); 1824 } 1825 } 1826 1827 static void 1828 pubkey_reset(Authctxt *authctxt) 1829 { 1830 Identity *id; 1831 1832 TAILQ_FOREACH(id, &authctxt->keys, next) 1833 id->tried = 0; 1834 } 1835 1836 static int 1837 try_identity(struct ssh *ssh, Identity *id) 1838 { 1839 if (!id->key) 1840 return (0); 1841 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1842 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 1843 debug("Skipped %s key %s for RSA/MD5 server", 1844 sshkey_type(id->key), id->filename); 1845 return (0); 1846 } 1847 return 1; 1848 } 1849 1850 static int 1851 userauth_pubkey(struct ssh *ssh) 1852 { 1853 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1854 Identity *id; 1855 int sent = 0; 1856 char *ident; 1857 1858 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1859 if (id->tried++) 1860 return (0); 1861 /* move key to the end of the queue */ 1862 TAILQ_REMOVE(&authctxt->keys, id, next); 1863 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1864 /* 1865 * send a test message if we have the public key. for 1866 * encrypted keys we cannot do this and have to load the 1867 * private key instead 1868 */ 1869 if (id->key != NULL) { 1870 if (try_identity(ssh, id)) { 1871 ident = format_identity(id); 1872 debug("Offering public key: %s", ident); 1873 free(ident); 1874 sent = send_pubkey_test(ssh, id); 1875 } 1876 } else { 1877 debug("Trying private key: %s", id->filename); 1878 id->key = load_identity_file(id); 1879 if (id->key != NULL) { 1880 if (try_identity(ssh, id)) { 1881 id->isprivate = 1; 1882 sent = sign_and_send_pubkey(ssh, id); 1883 } 1884 sshkey_free(id->key); 1885 id->key = NULL; 1886 id->isprivate = 0; 1887 } 1888 } 1889 if (sent) 1890 return (sent); 1891 } 1892 return (0); 1893 } 1894 1895 /* 1896 * Send userauth request message specifying keyboard-interactive method. 1897 */ 1898 static int 1899 userauth_kbdint(struct ssh *ssh) 1900 { 1901 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1902 int r; 1903 1904 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1905 return 0; 1906 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1907 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1908 debug3("userauth_kbdint: disable: no info_req_seen"); 1909 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1910 return 0; 1911 } 1912 1913 debug2("userauth_kbdint"); 1914 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1915 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1916 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1917 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1918 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1919 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1920 options.kbd_interactive_devices : "")) != 0 || 1921 (r = sshpkt_send(ssh)) != 0) 1922 fatal_fr(r, "send packet"); 1923 1924 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1925 return 1; 1926 } 1927 1928 /* 1929 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1930 */ 1931 static int 1932 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1933 { 1934 Authctxt *authctxt = ssh->authctxt; 1935 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1936 char *display_prompt = NULL, *response = NULL; 1937 u_char echo = 0; 1938 u_int num_prompts, i; 1939 int r; 1940 1941 debug2_f("entering"); 1942 1943 if (authctxt == NULL) 1944 fatal_f("no authentication context"); 1945 1946 authctxt->info_req_seen = 1; 1947 1948 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1949 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1950 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1951 goto out; 1952 if (strlen(name) > 0) 1953 logit("%s", name); 1954 if (strlen(inst) > 0) 1955 logit("%s", inst); 1956 1957 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1958 goto out; 1959 /* 1960 * Begin to build info response packet based on prompts requested. 1961 * We commit to providing the correct number of responses, so if 1962 * further on we run into a problem that prevents this, we have to 1963 * be sure and clean this up and send a correct error response. 1964 */ 1965 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1966 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1967 goto out; 1968 1969 debug2_f("num_prompts %d", num_prompts); 1970 for (i = 0; i < num_prompts; i++) { 1971 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1972 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1973 goto out; 1974 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1975 authctxt->server_user, options.host_key_alias ? 1976 options.host_key_alias : authctxt->host, prompt) == -1) 1977 fatal_f("asmprintf failed"); 1978 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1979 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1980 goto out; 1981 freezero(response, strlen(response)); 1982 free(prompt); 1983 free(display_prompt); 1984 display_prompt = response = prompt = NULL; 1985 } 1986 /* done with parsing incoming message. */ 1987 if ((r = sshpkt_get_end(ssh)) != 0 || 1988 (r = sshpkt_add_padding(ssh, 64)) != 0) 1989 goto out; 1990 r = sshpkt_send(ssh); 1991 out: 1992 if (response) 1993 freezero(response, strlen(response)); 1994 free(prompt); 1995 free(display_prompt); 1996 free(name); 1997 free(inst); 1998 free(lang); 1999 return r; 2000 } 2001 2002 static int 2003 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2004 const u_char *data, size_t datalen) 2005 { 2006 struct sshbuf *b; 2007 struct stat st; 2008 pid_t pid; 2009 int r, to[2], from[2], status; 2010 int sock = ssh_packet_get_connection_in(ssh); 2011 u_char rversion = 0, version = 2; 2012 void (*osigchld)(int); 2013 2014 *sigp = NULL; 2015 *lenp = 0; 2016 2017 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2018 error_f("not installed: %s", strerror(errno)); 2019 return -1; 2020 } 2021 if (fflush(stdout) != 0) { 2022 error_f("fflush: %s", strerror(errno)); 2023 return -1; 2024 } 2025 if (pipe(to) == -1) { 2026 error_f("pipe: %s", strerror(errno)); 2027 return -1; 2028 } 2029 if (pipe(from) == -1) { 2030 error_f("pipe: %s", strerror(errno)); 2031 return -1; 2032 } 2033 if ((pid = fork()) == -1) { 2034 error_f("fork: %s", strerror(errno)); 2035 return -1; 2036 } 2037 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2038 if (pid == 0) { 2039 close(from[0]); 2040 if (dup2(from[1], STDOUT_FILENO) == -1) 2041 fatal_f("dup2: %s", strerror(errno)); 2042 close(to[1]); 2043 if (dup2(to[0], STDIN_FILENO) == -1) 2044 fatal_f("dup2: %s", strerror(errno)); 2045 close(from[1]); 2046 close(to[0]); 2047 if (dup2(sock, STDERR_FILENO + 1) == -1) 2048 fatal_f("dup2: %s", strerror(errno)); 2049 sock = STDERR_FILENO + 1; 2050 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2051 closefrom(sock + 1); 2052 2053 debug3_f("[child] pid=%ld, exec %s", 2054 (long)getpid(), _PATH_SSH_KEY_SIGN); 2055 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2056 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2057 strerror(errno)); 2058 } 2059 close(from[1]); 2060 close(to[0]); 2061 sock = STDERR_FILENO + 1; 2062 2063 if ((b = sshbuf_new()) == NULL) 2064 fatal_f("sshbuf_new failed"); 2065 /* send # of sock, data to be signed */ 2066 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2067 (r = sshbuf_put_string(b, data, datalen)) != 0) 2068 fatal_fr(r, "buffer error"); 2069 if (ssh_msg_send(to[1], version, b) == -1) 2070 fatal_f("couldn't send request"); 2071 sshbuf_reset(b); 2072 r = ssh_msg_recv(from[0], b); 2073 close(from[0]); 2074 close(to[1]); 2075 if (r < 0) { 2076 error_f("no reply"); 2077 goto fail; 2078 } 2079 2080 errno = 0; 2081 while (waitpid(pid, &status, 0) == -1) { 2082 if (errno != EINTR) { 2083 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2084 goto fail; 2085 } 2086 } 2087 if (!WIFEXITED(status)) { 2088 error_f("exited abnormally"); 2089 goto fail; 2090 } 2091 if (WEXITSTATUS(status) != 0) { 2092 error_f("exited with status %d", WEXITSTATUS(status)); 2093 goto fail; 2094 } 2095 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2096 error_fr(r, "buffer error"); 2097 goto fail; 2098 } 2099 if (rversion != version) { 2100 error_f("bad version"); 2101 goto fail; 2102 } 2103 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2104 error_fr(r, "buffer error"); 2105 fail: 2106 ssh_signal(SIGCHLD, osigchld); 2107 sshbuf_free(b); 2108 return -1; 2109 } 2110 ssh_signal(SIGCHLD, osigchld); 2111 sshbuf_free(b); 2112 2113 return 0; 2114 } 2115 2116 static int 2117 userauth_hostbased(struct ssh *ssh) 2118 { 2119 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2120 struct sshkey *private = NULL; 2121 struct sshbuf *b = NULL; 2122 u_char *sig = NULL, *keyblob = NULL; 2123 char *fp = NULL, *chost = NULL, *lname = NULL; 2124 size_t siglen = 0, keylen = 0; 2125 int i, r, success = 0; 2126 2127 if (authctxt->ktypes == NULL) { 2128 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2129 authctxt->ktypes = authctxt->oktypes; 2130 } 2131 2132 /* 2133 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2134 * trying each hostkey that matches the type in turn. 2135 */ 2136 for (;;) { 2137 if (authctxt->active_ktype == NULL) 2138 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2139 if (authctxt->active_ktype == NULL || 2140 *authctxt->active_ktype == '\0') 2141 break; 2142 debug3_f("trying key type %s", authctxt->active_ktype); 2143 2144 /* check for a useful key */ 2145 private = NULL; 2146 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2147 if (authctxt->sensitive->keys[i] == NULL || 2148 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2149 continue; 2150 if (match_pattern_list( 2151 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2152 authctxt->active_ktype, 0) != 1) 2153 continue; 2154 /* we take and free the key */ 2155 private = authctxt->sensitive->keys[i]; 2156 authctxt->sensitive->keys[i] = NULL; 2157 break; 2158 } 2159 /* Found one */ 2160 if (private != NULL) 2161 break; 2162 /* No more keys of this type; advance */ 2163 authctxt->active_ktype = NULL; 2164 } 2165 if (private == NULL) { 2166 free(authctxt->oktypes); 2167 authctxt->oktypes = authctxt->ktypes = NULL; 2168 authctxt->active_ktype = NULL; 2169 debug("No more client hostkeys for hostbased authentication."); 2170 goto out; 2171 } 2172 2173 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2174 SSH_FP_DEFAULT)) == NULL) { 2175 error_f("sshkey_fingerprint failed"); 2176 goto out; 2177 } 2178 debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp); 2179 2180 /* figure out a name for the client host */ 2181 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2182 if (lname == NULL) { 2183 error_f("cannot get local ipaddr/name"); 2184 goto out; 2185 } 2186 2187 /* XXX sshbuf_put_stringf? */ 2188 xasprintf(&chost, "%s.", lname); 2189 debug2_f("chost %s", chost); 2190 2191 /* construct data */ 2192 if ((b = sshbuf_new()) == NULL) { 2193 error_f("sshbuf_new failed"); 2194 goto out; 2195 } 2196 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2197 error_fr(r, "sshkey_to_blob"); 2198 goto out; 2199 } 2200 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2201 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2202 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2203 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2204 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2205 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2206 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2207 (r = sshbuf_put_cstring(b, chost)) != 0 || 2208 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2209 error_fr(r, "buffer error"); 2210 goto out; 2211 } 2212 2213 #ifdef DEBUG_PK 2214 sshbuf_dump(b, stderr); 2215 #endif 2216 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2217 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2218 error("sign using hostkey %s %s failed", 2219 sshkey_ssh_name(private), fp); 2220 goto out; 2221 } 2222 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2223 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2224 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2225 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2226 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2227 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2228 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2229 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2230 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2231 (r = sshpkt_send(ssh)) != 0) { 2232 error_fr(r, "packet error"); 2233 goto out; 2234 } 2235 success = 1; 2236 2237 out: 2238 if (sig != NULL) 2239 freezero(sig, siglen); 2240 free(keyblob); 2241 free(lname); 2242 free(fp); 2243 free(chost); 2244 sshkey_free(private); 2245 sshbuf_free(b); 2246 2247 return success; 2248 } 2249 2250 #if KRB5 2251 static int 2252 ssh_krb5_helper(struct ssh *ssh, krb5_data *ap) 2253 { 2254 krb5_context xcontext = NULL; /* XXX share with ssh1 */ 2255 krb5_auth_context xauth_context = NULL; 2256 2257 krb5_context *context; 2258 krb5_auth_context *auth_context; 2259 krb5_error_code problem; 2260 const char *tkfile; 2261 struct stat buf; 2262 krb5_ccache ccache = NULL; 2263 const char *remotehost; 2264 int ret; 2265 const char *errtxt; 2266 2267 memset(ap, 0, sizeof(*ap)); 2268 2269 context = &xcontext; 2270 auth_context = &xauth_context; 2271 2272 problem = krb5_init_context(context); 2273 if (problem) { 2274 debug("Kerberos v5: krb5_init_context failed"); 2275 ret = 0; 2276 goto out; 2277 } 2278 2279 tkfile = krb5_cc_default_name(*context); 2280 if (strncmp(tkfile, "FILE:", 5) == 0) 2281 tkfile += 5; 2282 2283 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 2284 debug("Kerberos v5: could not get default ccache (permission denied)."); 2285 ret = 0; 2286 goto out; 2287 } 2288 2289 problem = krb5_cc_default(*context, &ccache); 2290 if (problem) { 2291 errtxt = krb5_get_error_message(*context, problem); 2292 if (errtxt != NULL) { 2293 debug("Kerberos v5: krb5_cc_default failed: %s", 2294 errtxt); 2295 krb5_free_error_message(*context, errtxt); 2296 } else 2297 debug("Kerberos v5: krb5_cc_default failed: %d", 2298 problem); 2299 ret = 0; 2300 goto out; 2301 } 2302 2303 remotehost = auth_get_canonical_hostname(ssh, 1); 2304 2305 problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED, 2306 "host", remotehost, NULL, ccache, ap); 2307 if (problem) { 2308 errtxt = krb5_get_error_message(*context, problem); 2309 if (errtxt != NULL) { 2310 debug("Kerberos v5: krb5_mk_req failed: %s", errtxt); 2311 krb5_free_error_message(*context, errtxt); 2312 } else 2313 debug("Kerberos v5: krb5_mk_req failed: %d", problem); 2314 ret = 0; 2315 goto out; 2316 } 2317 ret = 1; 2318 2319 out: 2320 if (ccache != NULL) 2321 krb5_cc_close(*context, ccache); 2322 if (*auth_context) 2323 krb5_auth_con_free(*context, *auth_context); 2324 if (*context) 2325 krb5_free_context(*context); 2326 return (ret); 2327 } 2328 2329 static int 2330 userauth_kerberos(struct ssh *ssh) 2331 { 2332 krb5_data ap; 2333 int r; 2334 Authctxt *authctxt = ssh->authctxt; 2335 2336 if (ssh_krb5_helper(ssh, &ap) == 0) 2337 return (0); 2338 2339 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2340 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2341 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2342 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2343 (r = sshpkt_put_string(ssh, ap.data, ap.length)) != 0 || 2344 (r = sshpkt_send(ssh)) != 0 || 2345 (r = ssh_packet_write_wait(ssh)) < 0) 2346 fatal("%s: %s", __func__, ssh_err(r)); 2347 2348 krb5_data_free(&ap); 2349 return (1); 2350 } 2351 #endif 2352 2353 /* find auth method */ 2354 2355 /* 2356 * given auth method name, if configurable options permit this method fill 2357 * in auth_ident field and return true, otherwise return false. 2358 */ 2359 static int 2360 authmethod_is_enabled(Authmethod *method) 2361 { 2362 if (method == NULL) 2363 return 0; 2364 /* return false if options indicate this method is disabled */ 2365 if (method->enabled == NULL || *method->enabled == 0) 2366 return 0; 2367 /* return false if batch mode is enabled but method needs interactive mode */ 2368 if (method->batch_flag != NULL && *method->batch_flag != 0) 2369 return 0; 2370 return 1; 2371 } 2372 2373 static Authmethod * 2374 authmethod_lookup(const char *name) 2375 { 2376 Authmethod *method = NULL; 2377 if (name != NULL) 2378 for (method = authmethods; method->name != NULL; method++) 2379 if (strcmp(name, method->name) == 0) 2380 return method; 2381 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2382 return NULL; 2383 } 2384 2385 /* XXX internal state */ 2386 static Authmethod *current = NULL; 2387 static char *supported = NULL; 2388 static char *preferred = NULL; 2389 2390 /* 2391 * Given the authentication method list sent by the server, return the 2392 * next method we should try. If the server initially sends a nil list, 2393 * use a built-in default list. 2394 */ 2395 static Authmethod * 2396 authmethod_get(char *authlist) 2397 { 2398 char *name = NULL; 2399 u_int next; 2400 2401 /* Use a suitable default if we're passed a nil list. */ 2402 if (authlist == NULL || strlen(authlist) == 0) 2403 authlist = options.preferred_authentications; 2404 2405 if (supported == NULL || strcmp(authlist, supported) != 0) { 2406 debug3("start over, passed a different list %s", authlist); 2407 free(supported); 2408 supported = xstrdup(authlist); 2409 preferred = options.preferred_authentications; 2410 debug3("preferred %s", preferred); 2411 current = NULL; 2412 } else if (current != NULL && authmethod_is_enabled(current)) 2413 return current; 2414 2415 for (;;) { 2416 if ((name = match_list(preferred, supported, &next)) == NULL) { 2417 debug("No more authentication methods to try."); 2418 current = NULL; 2419 return NULL; 2420 } 2421 preferred += next; 2422 debug3("authmethod_lookup %s", name); 2423 debug3("remaining preferred: %s", preferred); 2424 if ((current = authmethod_lookup(name)) != NULL && 2425 authmethod_is_enabled(current)) { 2426 debug3("authmethod_is_enabled %s", name); 2427 debug("Next authentication method: %s", name); 2428 free(name); 2429 return current; 2430 } 2431 free(name); 2432 } 2433 } 2434 2435 static char * 2436 authmethods_get(void) 2437 { 2438 Authmethod *method = NULL; 2439 struct sshbuf *b; 2440 char *list; 2441 int r; 2442 2443 if ((b = sshbuf_new()) == NULL) 2444 fatal_f("sshbuf_new failed"); 2445 for (method = authmethods; method->name != NULL; method++) { 2446 if (authmethod_is_enabled(method)) { 2447 if ((r = sshbuf_putf(b, "%s%s", 2448 sshbuf_len(b) ? "," : "", method->name)) != 0) 2449 fatal_fr(r, "buffer error"); 2450 } 2451 } 2452 if ((list = sshbuf_dup_string(b)) == NULL) 2453 fatal_f("sshbuf_dup_string failed"); 2454 sshbuf_free(b); 2455 return list; 2456 } 2457