1 /* $NetBSD: tls_server.c,v 1.6 2013/01/02 19:18:36 tron Exp $ */ 2 3 /*++ 4 /* NAME 5 /* tls_server 3 6 /* SUMMARY 7 /* server-side TLS engine 8 /* SYNOPSIS 9 /* #include <tls.h> 10 /* 11 /* TLS_APPL_STATE *tls_server_init(props) 12 /* const TLS_SERVER_INIT_PROPS *props; 13 /* 14 /* TLS_SESS_STATE *tls_server_start(props) 15 /* const TLS_SERVER_START_PROPS *props; 16 /* 17 /* TLS_SESS_STATE *tls_server_post_accept(TLScontext) 18 /* TLS_SESS_STATE *TLScontext; 19 /* 20 /* void tls_server_stop(app_ctx, stream, failure, TLScontext) 21 /* TLS_APPL_STATE *app_ctx; 22 /* VSTREAM *stream; 23 /* int failure; 24 /* TLS_SESS_STATE *TLScontext; 25 /* DESCRIPTION 26 /* This module is the interface between Postfix TLS servers, 27 /* the OpenSSL library, and the TLS entropy and cache manager. 28 /* 29 /* See "EVENT_DRIVEN APPLICATIONS" below for using this code 30 /* in event-driven programs. 31 /* 32 /* tls_server_init() is called once when the SMTP server 33 /* initializes. 34 /* Certificate details are also decided during this phase, 35 /* so that peer-specific behavior is not possible. 36 /* 37 /* tls_server_start() activates the TLS feature for the VSTREAM 38 /* passed as argument. We assume that network buffers are flushed 39 /* and the TLS handshake can begin immediately. 40 /* 41 /* tls_server_stop() sends the "close notify" alert via 42 /* SSL_shutdown() to the peer and resets all connection specific 43 /* TLS data. As RFC2487 does not specify a separate shutdown, it 44 /* is assumed that the underlying TCP connection is shut down 45 /* immediately afterwards. Any further writes to the channel will 46 /* be discarded, and any further reads will report end-of-file. 47 /* If the failure flag is set, no SSL_shutdown() handshake is performed. 48 /* 49 /* Once the TLS connection is initiated, information about the TLS 50 /* state is available via the TLScontext structure: 51 /* .IP TLScontext->protocol 52 /* the protocol name (SSLv2, SSLv3, TLSv1), 53 /* .IP TLScontext->cipher_name 54 /* the cipher name (e.g. RC4/MD5), 55 /* .IP TLScontext->cipher_usebits 56 /* the number of bits actually used (e.g. 40), 57 /* .IP TLScontext->cipher_algbits 58 /* the number of bits the algorithm is based on (e.g. 128). 59 /* .PP 60 /* The last two values may differ from each other when export-strength 61 /* encryption is used. 62 /* 63 /* If the peer offered a certificate, part of the certificate data are 64 /* available as: 65 /* .IP TLScontext->peer_status 66 /* A bitmask field that records the status of the peer certificate 67 /* verification. One or more of TLS_CERT_FLAG_PRESENT and 68 /* TLS_CERT_FLAG_TRUSTED. 69 /* .IP TLScontext->peer_CN 70 /* Extracted CommonName of the peer, or zero-length string 71 /* when information could not be extracted. 72 /* .IP TLScontext->issuer_CN 73 /* Extracted CommonName of the issuer, or zero-length string 74 /* when information could not be extracted. 75 /* .IP TLScontext->peer_fingerprint 76 /* Fingerprint of the certificate, or zero-length string when no peer 77 /* certificate is available. 78 /* .PP 79 /* If no peer certificate is presented the peer_status is set to 0. 80 /* EVENT_DRIVEN APPLICATIONS 81 /* .ad 82 /* .fi 83 /* Event-driven programs manage multiple I/O channels. Such 84 /* programs cannot use the synchronous VSTREAM-over-TLS 85 /* implementation that the current TLS library provides, 86 /* including tls_server_stop() and the underlying tls_stream(3) 87 /* and tls_bio_ops(3) routines. 88 /* 89 /* With the current TLS library implementation, this means 90 /* that the application is responsible for calling and retrying 91 /* SSL_accept(), SSL_read(), SSL_write() and SSL_shutdown(). 92 /* 93 /* To maintain control over TLS I/O, an event-driven server 94 /* invokes tls_server_start() with a null VSTREAM argument and 95 /* with an fd argument that specifies the I/O file descriptor. 96 /* Then, tls_server_start() performs all the necessary 97 /* preparations before the TLS handshake and returns a partially 98 /* populated TLS context. The event-driven application is then 99 /* responsible for invoking SSL_accept(), and if successful, 100 /* for invoking tls_server_post_accept() to finish the work 101 /* that was started by tls_server_start(). In case of unrecoverable 102 /* failure, tls_server_post_accept() destroys the TLS context 103 /* and returns a null pointer value. 104 /* LICENSE 105 /* .ad 106 /* .fi 107 /* This software is free. You can do with it whatever you want. 108 /* The original author kindly requests that you acknowledge 109 /* the use of his software. 110 /* AUTHOR(S) 111 /* Originally written by: 112 /* Lutz Jaenicke 113 /* BTU Cottbus 114 /* Allgemeine Elektrotechnik 115 /* Universitaetsplatz 3-4 116 /* D-03044 Cottbus, Germany 117 /* 118 /* Updated by: 119 /* Wietse Venema 120 /* IBM T.J. Watson Research 121 /* P.O. Box 704 122 /* Yorktown Heights, NY 10598, USA 123 /* 124 /* Victor Duchovni 125 /* Morgan Stanley 126 /*--*/ 127 128 /* System library. */ 129 130 #include <sys_defs.h> 131 132 #ifdef USE_TLS 133 #include <unistd.h> 134 #include <string.h> 135 136 /* Utility library. */ 137 138 #include <mymalloc.h> 139 #include <vstring.h> 140 #include <vstream.h> 141 #include <dict.h> 142 #include <stringops.h> 143 #include <msg.h> 144 #include <hex_code.h> 145 #include <iostuff.h> /* non-blocking */ 146 147 /* Global library. */ 148 149 #include <mail_params.h> 150 151 /* TLS library. */ 152 153 #include <tls_mgr.h> 154 #define TLS_INTERNAL 155 #include <tls.h> 156 157 #define STR(x) vstring_str(x) 158 #define LEN(x) VSTRING_LEN(x) 159 160 /* Application-specific. */ 161 162 /* 163 * The session_id_context indentifies the service that created a session. 164 * This information is used to distinguish between multiple TLS-based 165 * servers running on the same server. We use the name of the mail system. 166 */ 167 static const char server_session_id_context[] = "Postfix/TLS"; 168 169 /* get_server_session_cb - callback to retrieve session from server cache */ 170 171 static SSL_SESSION *get_server_session_cb(SSL *ssl, unsigned char *session_id, 172 int session_id_length, 173 int *unused_copy) 174 { 175 const char *myname = "get_server_session_cb"; 176 TLS_SESS_STATE *TLScontext; 177 VSTRING *cache_id; 178 VSTRING *session_data = vstring_alloc(2048); 179 SSL_SESSION *session = 0; 180 181 if ((TLScontext = SSL_get_ex_data(ssl, TLScontext_index)) == 0) 182 msg_panic("%s: null TLScontext in session lookup callback", myname); 183 184 #define GEN_CACHE_ID(buf, id, len, service) \ 185 do { \ 186 buf = vstring_alloc(2 * (len + strlen(service))); \ 187 hex_encode(buf, (char *) (id), (len)); \ 188 vstring_sprintf_append(buf, "&s=%s", (service)); \ 189 vstring_sprintf_append(buf, "&l=%ld", (long) SSLeay()); \ 190 } while (0) 191 192 193 GEN_CACHE_ID(cache_id, session_id, session_id_length, TLScontext->serverid); 194 195 if (TLScontext->log_mask & TLS_LOG_CACHE) 196 msg_info("%s: looking up session %s in %s cache", TLScontext->namaddr, 197 STR(cache_id), TLScontext->cache_type); 198 199 /* 200 * Load the session from cache and decode it. 201 */ 202 if (tls_mgr_lookup(TLScontext->cache_type, STR(cache_id), 203 session_data) == TLS_MGR_STAT_OK) { 204 session = tls_session_activate(STR(session_data), LEN(session_data)); 205 if (session && (TLScontext->log_mask & TLS_LOG_CACHE)) 206 msg_info("%s: reloaded session %s from %s cache", 207 TLScontext->namaddr, STR(cache_id), 208 TLScontext->cache_type); 209 } 210 211 /* 212 * Clean up. 213 */ 214 vstring_free(cache_id); 215 vstring_free(session_data); 216 217 return (session); 218 } 219 220 /* uncache_session - remove session from internal & external cache */ 221 222 static void uncache_session(SSL_CTX *ctx, TLS_SESS_STATE *TLScontext) 223 { 224 VSTRING *cache_id; 225 SSL_SESSION *session = SSL_get_session(TLScontext->con); 226 227 SSL_CTX_remove_session(ctx, session); 228 229 if (TLScontext->cache_type == 0) 230 return; 231 232 GEN_CACHE_ID(cache_id, session->session_id, session->session_id_length, 233 TLScontext->serverid); 234 235 if (TLScontext->log_mask & TLS_LOG_CACHE) 236 msg_info("%s: remove session %s from %s cache", TLScontext->namaddr, 237 STR(cache_id), TLScontext->cache_type); 238 239 tls_mgr_delete(TLScontext->cache_type, STR(cache_id)); 240 vstring_free(cache_id); 241 } 242 243 /* new_server_session_cb - callback to save session to server cache */ 244 245 static int new_server_session_cb(SSL *ssl, SSL_SESSION *session) 246 { 247 const char *myname = "new_server_session_cb"; 248 VSTRING *cache_id; 249 TLS_SESS_STATE *TLScontext; 250 VSTRING *session_data; 251 252 if ((TLScontext = SSL_get_ex_data(ssl, TLScontext_index)) == 0) 253 msg_panic("%s: null TLScontext in new session callback", myname); 254 255 GEN_CACHE_ID(cache_id, session->session_id, session->session_id_length, 256 TLScontext->serverid); 257 258 if (TLScontext->log_mask & TLS_LOG_CACHE) 259 msg_info("%s: save session %s to %s cache", TLScontext->namaddr, 260 STR(cache_id), TLScontext->cache_type); 261 262 /* 263 * Passivate and save the session state. 264 */ 265 session_data = tls_session_passivate(session); 266 if (session_data) 267 tls_mgr_update(TLScontext->cache_type, STR(cache_id), 268 STR(session_data), LEN(session_data)); 269 270 /* 271 * Clean up. 272 */ 273 if (session_data) 274 vstring_free(session_data); 275 vstring_free(cache_id); 276 SSL_SESSION_free(session); /* 200502 */ 277 278 return (1); 279 } 280 281 /* tls_server_init - initialize the server-side TLS engine */ 282 283 TLS_APPL_STATE *tls_server_init(const TLS_SERVER_INIT_PROPS *props) 284 { 285 SSL_CTX *server_ctx; 286 long off = 0; 287 int verify_flags = SSL_VERIFY_NONE; 288 int cachable; 289 int protomask; 290 TLS_APPL_STATE *app_ctx; 291 const EVP_MD *md_alg; 292 unsigned int md_len; 293 int log_mask; 294 295 /* 296 * Convert user loglevel to internal logmask. 297 */ 298 log_mask = tls_log_mask(props->log_param, props->log_level); 299 300 if (log_mask & TLS_LOG_VERBOSE) 301 msg_info("initializing the server-side TLS engine"); 302 303 /* 304 * Load (mostly cipher related) TLS-library internal main.cf parameters. 305 */ 306 tls_param_init(); 307 308 /* 309 * Detect mismatch between compile-time headers and run-time library. 310 */ 311 tls_check_version(); 312 313 /* 314 * Initialize the OpenSSL library by the book! To start with, we must 315 * initialize the algorithms. We want cleartext error messages instead of 316 * just error codes, so we load the error_strings. 317 */ 318 SSL_load_error_strings(); 319 OpenSSL_add_ssl_algorithms(); 320 321 /* 322 * First validate the protocols. If these are invalid, we can't continue. 323 */ 324 protomask = tls_protocol_mask(props->protocols); 325 if (protomask == TLS_PROTOCOL_INVALID) { 326 /* tls_protocol_mask() logs no warning. */ 327 msg_warn("Invalid TLS protocol list \"%s\": disabling TLS support", 328 props->protocols); 329 return (0); 330 } 331 332 /* 333 * Create an application data index for SSL objects, so that we can 334 * attach TLScontext information; this information is needed inside 335 * tls_verify_certificate_callback(). 336 */ 337 if (TLScontext_index < 0) { 338 if ((TLScontext_index = SSL_get_ex_new_index(0, 0, 0, 0, 0)) < 0) { 339 msg_warn("Cannot allocate SSL application data index: " 340 "disabling TLS support"); 341 return (0); 342 } 343 } 344 345 /* 346 * If the administrator specifies an unsupported digest algorithm, fail 347 * now, rather than in the middle of a TLS handshake. 348 */ 349 if ((md_alg = EVP_get_digestbyname(props->fpt_dgst)) == 0) { 350 msg_warn("Digest algorithm \"%s\" not found: disabling TLS support", 351 props->fpt_dgst); 352 return (0); 353 } 354 355 /* 356 * Sanity check: Newer shared libraries may use larger digests. 357 */ 358 if ((md_len = EVP_MD_size(md_alg)) > EVP_MAX_MD_SIZE) { 359 msg_warn("Digest algorithm \"%s\" output size %u too large:" 360 " disabling TLS support", props->fpt_dgst, md_len); 361 return (0); 362 } 363 364 /* 365 * Initialize the PRNG (Pseudo Random Number Generator) with some seed 366 * from external and internal sources. Don't enable TLS without some real 367 * entropy. 368 */ 369 if (tls_ext_seed(var_tls_daemon_rand_bytes) < 0) { 370 msg_warn("no entropy for TLS key generation: disabling TLS support"); 371 return (0); 372 } 373 tls_int_seed(); 374 375 /* 376 * The SSL/TLS specifications require the client to send a message in the 377 * oldest specification it understands with the highest level it 378 * understands in the message. Netscape communicator can still 379 * communicate with SSLv2 servers, so it sends out a SSLv2 client hello. 380 * To deal with it, our server must be SSLv2 aware (even if we don't like 381 * SSLv2), so we need to have the SSLv23 server here. If we want to limit 382 * the protocol level, we can add an option to not use SSLv2/v3/TLSv1 383 * later. 384 */ 385 ERR_clear_error(); 386 if ((server_ctx = SSL_CTX_new(SSLv23_server_method())) == 0) { 387 msg_warn("cannot allocate server SSL_CTX: disabling TLS support"); 388 tls_print_errors(); 389 return (0); 390 } 391 392 /* 393 * See the verify callback in tls_verify.c 394 */ 395 SSL_CTX_set_verify_depth(server_ctx, props->verifydepth + 1); 396 397 /* 398 * Protocol work-arounds, OpenSSL version dependent. 399 */ 400 off |= tls_bug_bits(); 401 SSL_CTX_set_options(server_ctx, off); 402 403 /* 404 * Global protocol selection. 405 */ 406 if (protomask != 0) 407 SSL_CTX_set_options(server_ctx, 408 ((protomask & TLS_PROTOCOL_TLSv1) ? SSL_OP_NO_TLSv1 : 0L) 409 | ((protomask & TLS_PROTOCOL_TLSv1_1) ? SSL_OP_NO_TLSv1_1 : 0L) 410 | ((protomask & TLS_PROTOCOL_TLSv1_2) ? SSL_OP_NO_TLSv1_2 : 0L) 411 | ((protomask & TLS_PROTOCOL_SSLv3) ? SSL_OP_NO_SSLv3 : 0L) 412 | ((protomask & TLS_PROTOCOL_SSLv2) ? SSL_OP_NO_SSLv2 : 0L)); 413 414 #if OPENSSL_VERSION_NUMBER >= 0x0090700fL 415 416 /* 417 * Some sites may want to give the client less rope. On the other hand, 418 * this could trigger inter-operability issues, the client should not 419 * offer ciphers it implements poorly, but this hasn't stopped some 420 * vendors from getting it wrong. 421 * 422 * XXX: Given OpenSSL's security history, nobody should still be using 423 * 0.9.7, let alone 0.9.6 or earlier. Warning added to TLS_README.html. 424 */ 425 if (var_tls_preempt_clist) 426 SSL_CTX_set_options(server_ctx, SSL_OP_CIPHER_SERVER_PREFERENCE); 427 #endif 428 429 /* 430 * Set the call-back routine to debug handshake progress. 431 */ 432 if (log_mask & TLS_LOG_DEBUG) 433 SSL_CTX_set_info_callback(server_ctx, tls_info_callback); 434 435 /* 436 * Load the CA public key certificates for both the server cert and for 437 * the verification of client certificates. As provided by OpenSSL we 438 * support two types of CA certificate handling: One possibility is to 439 * add all CA certificates to one large CAfile, the other possibility is 440 * a directory pointed to by CApath, containing separate files for each 441 * CA with softlinks named after the hash values of the certificate. The 442 * first alternative has the advantage that the file is opened and read 443 * at startup time, so that you don't have the hassle to maintain another 444 * copy of the CApath directory for chroot-jail. 445 */ 446 if (tls_set_ca_certificate_info(server_ctx, 447 props->CAfile, props->CApath) < 0) { 448 /* tls_set_ca_certificate_info() already logs a warning. */ 449 SSL_CTX_free(server_ctx); /* 200411 */ 450 return (0); 451 } 452 453 /* 454 * Load the server public key certificate and private key from file and 455 * check whether the cert matches the key. We can use RSA certificates 456 * ("cert") DSA certificates ("dcert") or ECDSA certificates ("eccert"). 457 * All three can be made available at the same time. The CA certificates 458 * for all three are handled in the same setup already finished. Which 459 * one is used depends on the cipher negotiated (that is: the first 460 * cipher listed by the client which does match the server). A client 461 * with RSA only (e.g. Netscape) will use the RSA certificate only. A 462 * client with openssl-library will use RSA first if not especially 463 * changed in the cipher setup. 464 */ 465 if (tls_set_my_certificate_key_info(server_ctx, 466 props->cert_file, 467 props->key_file, 468 props->dcert_file, 469 props->dkey_file, 470 props->eccert_file, 471 props->eckey_file) < 0) { 472 /* tls_set_my_certificate_key_info() already logs a warning. */ 473 SSL_CTX_free(server_ctx); /* 200411 */ 474 return (0); 475 } 476 477 /* 478 * According to OpenSSL documentation, a temporary RSA key is needed when 479 * export ciphers are in use, because the certified key cannot be 480 * directly used. 481 */ 482 SSL_CTX_set_tmp_rsa_callback(server_ctx, tls_tmp_rsa_cb); 483 484 /* 485 * Diffie-Hellman key generation parameters can either be loaded from 486 * files (preferred) or taken from compiled in values. First, set the 487 * callback that will select the values when requested, then load the 488 * (possibly) available DH parameters from files. We are generous with 489 * the error handling, since we do have default values compiled in, so we 490 * will not abort but just log the error message. 491 */ 492 SSL_CTX_set_tmp_dh_callback(server_ctx, tls_tmp_dh_cb); 493 if (*props->dh1024_param_file != 0) 494 tls_set_dh_from_file(props->dh1024_param_file, 1024); 495 if (*props->dh512_param_file != 0) 496 tls_set_dh_from_file(props->dh512_param_file, 512); 497 498 /* 499 * Enable EECDH if available, errors are not fatal, we just keep going 500 * with any remaining key-exchange algorithms. 501 */ 502 (void) tls_set_eecdh_curve(server_ctx, props->eecdh_grade); 503 504 /* 505 * If we want to check client certificates, we have to indicate it in 506 * advance. By now we only allow to decide on a global basis. If we want 507 * to allow certificate based relaying, we must ask the client to provide 508 * one with SSL_VERIFY_PEER. The client now can decide, whether it 509 * provides one or not. We can enforce a failure of the negotiation with 510 * SSL_VERIFY_FAIL_IF_NO_PEER_CERT, if we do not allow a connection 511 * without one. In the "server hello" following the initialization by the 512 * "client hello" the server must provide a list of CAs it is willing to 513 * accept. Some clever clients will then select one from the list of 514 * available certificates matching these CAs. Netscape Communicator will 515 * present the list of certificates for selecting the one to be sent, or 516 * it will issue a warning, if there is no certificate matching the 517 * available CAs. 518 * 519 * With regard to the purpose of the certificate for relaying, we might like 520 * a later negotiation, maybe relaying would already be allowed for other 521 * reasons, but this would involve severe changes in the internal postfix 522 * logic, so we have to live with it the way it is. 523 */ 524 if (props->ask_ccert) 525 verify_flags = SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE; 526 SSL_CTX_set_verify(server_ctx, verify_flags, 527 tls_verify_certificate_callback); 528 if (*props->CAfile) 529 SSL_CTX_set_client_CA_list(server_ctx, 530 SSL_load_client_CA_file(props->CAfile)); 531 532 /* 533 * Initialize our own TLS server handle, before diving into the details 534 * of TLS session cache management. 535 */ 536 app_ctx = tls_alloc_app_context(server_ctx, log_mask); 537 538 /* 539 * The session cache is implemented by the tlsmgr(8) server. 540 * 541 * XXX 200502 Surprise: when OpenSSL purges an entry from the in-memory 542 * cache, it also attempts to purge the entry from the on-disk cache. 543 * This is undesirable, especially when we set the in-memory cache size 544 * to 1. For this reason we don't allow OpenSSL to purge on-disk cache 545 * entries, and leave it up to the tlsmgr process instead. Found by 546 * Victor Duchovni. 547 */ 548 549 if (tls_mgr_policy(props->cache_type, &cachable) != TLS_MGR_STAT_OK) 550 cachable = 0; 551 552 if (cachable || props->set_sessid) { 553 554 /* 555 * Initialize the session cache. 556 * 557 * With a large number of concurrent smtpd(8) processes, it is not a 558 * good idea to cache multiple large session objects in each process. 559 * We set the internal cache size to 1, and don't register a 560 * "remove_cb" so as to avoid deleting good sessions from the 561 * external cache prematurely (when the internal cache is full, 562 * OpenSSL removes sessions from the external cache also)! 563 * 564 * This makes SSL_CTX_remove_session() not useful for flushing broken 565 * sessions from the external cache, so we must delete them directly 566 * (not via a callback). 567 * 568 * Set a session id context to identify to what type of server process 569 * created a session. In our case, the context is simply the name of 570 * the mail system: "Postfix/TLS". 571 */ 572 SSL_CTX_sess_set_cache_size(server_ctx, 1); 573 SSL_CTX_set_session_id_context(server_ctx, 574 (void *) &server_session_id_context, 575 sizeof(server_session_id_context)); 576 SSL_CTX_set_session_cache_mode(server_ctx, 577 SSL_SESS_CACHE_SERVER | 578 SSL_SESS_CACHE_NO_AUTO_CLEAR); 579 if (cachable) { 580 app_ctx->cache_type = mystrdup(props->cache_type); 581 582 SSL_CTX_sess_set_get_cb(server_ctx, get_server_session_cb); 583 SSL_CTX_sess_set_new_cb(server_ctx, new_server_session_cb); 584 } 585 586 /* 587 * OpenSSL ignores timed-out sessions. We need to set the internal 588 * cache timeout at least as high as the external cache timeout. This 589 * applies even if no internal cache is used. 590 */ 591 SSL_CTX_set_timeout(server_ctx, props->scache_timeout); 592 } else { 593 594 /* 595 * If we have no external cache, disable all caching. No use wasting 596 * server memory resources with sessions they are unlikely to be able 597 * to reuse. 598 */ 599 SSL_CTX_set_session_cache_mode(server_ctx, SSL_SESS_CACHE_OFF); 600 } 601 602 return (app_ctx); 603 } 604 605 /* 606 * This is the actual startup routine for a new connection. We expect that 607 * the SMTP buffers are flushed and the "220 Ready to start TLS" was sent to 608 * the client, so that we can immediately start the TLS handshake process. 609 */ 610 TLS_SESS_STATE *tls_server_start(const TLS_SERVER_START_PROPS *props) 611 { 612 int sts; 613 TLS_SESS_STATE *TLScontext; 614 const char *cipher_list; 615 TLS_APPL_STATE *app_ctx = props->ctx; 616 int log_mask = app_ctx->log_mask; 617 618 /* 619 * Implicitly enable logging of trust chain errors when verified certs 620 * are required. 621 */ 622 if (props->requirecert) 623 log_mask |= TLS_LOG_UNTRUSTED; 624 625 if (log_mask & TLS_LOG_VERBOSE) 626 msg_info("setting up TLS connection from %s", props->namaddr); 627 628 cipher_list = tls_set_ciphers(app_ctx, "TLS", props->cipher_grade, 629 props->cipher_exclusions); 630 if (cipher_list == 0) { 631 msg_warn("%s: %s: aborting TLS session", props->namaddr, 632 vstring_str(app_ctx->why)); 633 return (0); 634 } 635 if (log_mask & TLS_LOG_VERBOSE) 636 msg_info("%s: TLS cipher list \"%s\"", props->namaddr, cipher_list); 637 638 /* 639 * Allocate a new TLScontext for the new connection and get an SSL 640 * structure. Add the location of TLScontext to the SSL to later retrieve 641 * the information inside the tls_verify_certificate_callback(). 642 */ 643 TLScontext = tls_alloc_sess_context(log_mask, props->namaddr); 644 TLScontext->cache_type = app_ctx->cache_type; 645 646 TLScontext->serverid = mystrdup(props->serverid); 647 TLScontext->am_server = 1; 648 649 TLScontext->fpt_dgst = mystrdup(props->fpt_dgst); 650 TLScontext->stream = props->stream; 651 652 ERR_clear_error(); 653 if ((TLScontext->con = (SSL *) SSL_new(app_ctx->ssl_ctx)) == 0) { 654 msg_warn("Could not allocate 'TLScontext->con' with SSL_new()"); 655 tls_print_errors(); 656 tls_free_context(TLScontext); 657 return (0); 658 } 659 if (!SSL_set_ex_data(TLScontext->con, TLScontext_index, TLScontext)) { 660 msg_warn("Could not set application data for 'TLScontext->con'"); 661 tls_print_errors(); 662 tls_free_context(TLScontext); 663 return (0); 664 } 665 666 /* 667 * Before really starting anything, try to seed the PRNG a little bit 668 * more. 669 */ 670 tls_int_seed(); 671 (void) tls_ext_seed(var_tls_daemon_rand_bytes); 672 673 /* 674 * Initialize the SSL connection to accept state. This should not be 675 * necessary anymore since 0.9.3, but the call is still in the library 676 * and maintaining compatibility never hurts. 677 */ 678 SSL_set_accept_state(TLScontext->con); 679 680 /* 681 * Connect the SSL connection with the network socket. 682 */ 683 if (SSL_set_fd(TLScontext->con, props->stream == 0 ? props->fd : 684 vstream_fileno(props->stream)) != 1) { 685 msg_info("SSL_set_fd error to %s", props->namaddr); 686 tls_print_errors(); 687 uncache_session(app_ctx->ssl_ctx, TLScontext); 688 tls_free_context(TLScontext); 689 return (0); 690 } 691 692 /* 693 * If the debug level selected is high enough, all of the data is dumped: 694 * TLS_LOG_TLSPKTS will dump the SSL negotiation, TLS_LOG_ALLPKTS will 695 * dump everything. 696 * 697 * We do have an SSL_set_fd() and now suddenly a BIO_ routine is called? 698 * Well there is a BIO below the SSL routines that is automatically 699 * created for us, so we can use it for debugging purposes. 700 */ 701 if (log_mask & TLS_LOG_TLSPKTS) 702 BIO_set_callback(SSL_get_rbio(TLScontext->con), tls_bio_dump_cb); 703 704 /* 705 * If we don't trigger the handshake in the library, leave control over 706 * SSL_accept/read/write/etc with the application. 707 */ 708 if (props->stream == 0) 709 return (TLScontext); 710 711 /* 712 * Turn on non-blocking I/O so that we can enforce timeouts on network 713 * I/O. 714 */ 715 non_blocking(vstream_fileno(props->stream), NON_BLOCKING); 716 717 /* 718 * Start TLS negotiations. This process is a black box that invokes our 719 * call-backs for session caching and certificate verification. 720 * 721 * Error handling: If the SSL handhake fails, we print out an error message 722 * and remove all TLS state concerning this session. 723 */ 724 sts = tls_bio_accept(vstream_fileno(props->stream), props->timeout, 725 TLScontext); 726 if (sts <= 0) { 727 if (ERR_peek_error() != 0) { 728 msg_info("SSL_accept error from %s: %d", props->namaddr, sts); 729 tls_print_errors(); 730 } else if (errno != 0) { 731 msg_info("SSL_accept error from %s: %m", props->namaddr); 732 } else { 733 msg_info("SSL_accept error from %s: lost connection", 734 props->namaddr); 735 } 736 tls_free_context(TLScontext); 737 return (0); 738 } 739 return (tls_server_post_accept(TLScontext)); 740 } 741 742 /* tls_server_post_accept - post-handshake processing */ 743 744 TLS_SESS_STATE *tls_server_post_accept(TLS_SESS_STATE *TLScontext) 745 { 746 const SSL_CIPHER *cipher; 747 X509 *peer; 748 char buf[CCERT_BUFSIZ]; 749 750 /* Turn off packet dump if only dumping the handshake */ 751 if ((TLScontext->log_mask & TLS_LOG_ALLPKTS) == 0) 752 BIO_set_callback(SSL_get_rbio(TLScontext->con), 0); 753 754 /* 755 * The caller may want to know if this session was reused or if a new 756 * session was negotiated. 757 */ 758 TLScontext->session_reused = SSL_session_reused(TLScontext->con); 759 if ((TLScontext->log_mask & TLS_LOG_CACHE) && TLScontext->session_reused) 760 msg_info("%s: Reusing old session", TLScontext->namaddr); 761 762 /* 763 * Let's see whether a peer certificate is available and what is the 764 * actual information. We want to save it for later use. 765 */ 766 peer = SSL_get_peer_certificate(TLScontext->con); 767 if (peer != NULL) { 768 TLScontext->peer_status |= TLS_CERT_FLAG_PRESENT; 769 if (SSL_get_verify_result(TLScontext->con) == X509_V_OK) 770 TLScontext->peer_status |= TLS_CERT_FLAG_TRUSTED; 771 772 if (TLScontext->log_mask & TLS_LOG_VERBOSE) { 773 X509_NAME_oneline(X509_get_subject_name(peer), 774 buf, sizeof(buf)); 775 msg_info("subject=%s", buf); 776 X509_NAME_oneline(X509_get_issuer_name(peer), 777 buf, sizeof(buf)); 778 msg_info("issuer=%s", buf); 779 } 780 TLScontext->peer_CN = tls_peer_CN(peer, TLScontext); 781 TLScontext->issuer_CN = tls_issuer_CN(peer, TLScontext); 782 TLScontext->peer_fingerprint = 783 tls_fingerprint(peer, TLScontext->fpt_dgst); 784 TLScontext->peer_pkey_fprint = 785 tls_pkey_fprint(peer, TLScontext->fpt_dgst); 786 787 if (TLScontext->log_mask & (TLS_LOG_VERBOSE | TLS_LOG_PEERCERT)) { 788 msg_info("%s: subject_CN=%s, issuer=%s, fingerprint=%s" 789 ", pkey_fingerprint=%s", 790 TLScontext->namaddr, 791 TLScontext->peer_CN, TLScontext->issuer_CN, 792 TLScontext->peer_fingerprint, 793 TLScontext->peer_pkey_fprint); 794 } 795 X509_free(peer); 796 } else { 797 TLScontext->peer_CN = mystrdup(""); 798 TLScontext->issuer_CN = mystrdup(""); 799 TLScontext->peer_fingerprint = mystrdup(""); 800 } 801 802 /* 803 * Finally, collect information about protocol and cipher for logging 804 */ 805 TLScontext->protocol = SSL_get_version(TLScontext->con); 806 cipher = SSL_get_current_cipher(TLScontext->con); 807 TLScontext->cipher_name = SSL_CIPHER_get_name(cipher); 808 TLScontext->cipher_usebits = SSL_CIPHER_get_bits(cipher, 809 &(TLScontext->cipher_algbits)); 810 811 /* 812 * If the library triggered the SSL handshake, switch to the 813 * tls_timed_read/write() functions and make the TLScontext available to 814 * those functions. Otherwise, leave control over SSL_read/write/etc. 815 * with the application. 816 */ 817 if (TLScontext->stream != 0) 818 tls_stream_start(TLScontext->stream, TLScontext); 819 820 /* 821 * All the key facts in a single log entry. 822 */ 823 if (TLScontext->log_mask & TLS_LOG_SUMMARY) 824 msg_info("%s TLS connection established from %s: %s with cipher %s " 825 "(%d/%d bits)", !TLS_CERT_IS_PRESENT(TLScontext) ? "Anonymous" 826 : TLS_CERT_IS_TRUSTED(TLScontext) ? "Trusted" : "Untrusted", 827 TLScontext->namaddr, TLScontext->protocol, TLScontext->cipher_name, 828 TLScontext->cipher_usebits, TLScontext->cipher_algbits); 829 830 tls_int_seed(); 831 832 return (TLScontext); 833 } 834 835 #endif /* USE_TLS */ 836