1/* $NetBSD: tls_server.c,v 1.5 2012/06/09 11:32:20 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 */ 167static const char server_session_id_context[] = "Postfix/TLS"; 168 169/* get_server_session_cb - callback to retrieve session from server cache */ 170 171static 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_level >= 2) 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_level >= 2)) 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 222static 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_level >= 2) 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 245static 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_level >= 2) 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 283TLS_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; 293 294 if (props->log_level >= 2) 295 msg_info("initializing the server-side TLS engine"); 296 297 /* 298 * Load (mostly cipher related) TLS-library internal main.cf parameters. 299 */ 300 tls_param_init(); 301 302 /* 303 * Detect mismatch between compile-time headers and run-time library. 304 */ 305 tls_check_version(); 306 307 /* 308 * Initialize the OpenSSL library by the book! To start with, we must 309 * initialize the algorithms. We want cleartext error messages instead of 310 * just error codes, so we load the error_strings. 311 */ 312 SSL_load_error_strings(); 313 OpenSSL_add_ssl_algorithms(); 314 315 /* 316 * First validate the protocols. If these are invalid, we can't continue. 317 */ 318 protomask = tls_protocol_mask(props->protocols); 319 if (protomask == TLS_PROTOCOL_INVALID) { 320 /* tls_protocol_mask() logs no warning. */ 321 msg_warn("Invalid TLS protocol list \"%s\": disabling TLS support", 322 props->protocols); 323 return (0); 324 } 325 326 /* 327 * Create an application data index for SSL objects, so that we can 328 * attach TLScontext information; this information is needed inside 329 * tls_verify_certificate_callback(). 330 */ 331 if (TLScontext_index < 0) { 332 if ((TLScontext_index = SSL_get_ex_new_index(0, 0, 0, 0, 0)) < 0) { 333 msg_warn("Cannot allocate SSL application data index: " 334 "disabling TLS support"); 335 return (0); 336 } 337 } 338 339 /* 340 * If the administrator specifies an unsupported digest algorithm, fail 341 * now, rather than in the middle of a TLS handshake. 342 */ 343 if ((md_alg = EVP_get_digestbyname(props->fpt_dgst)) == 0) { 344 msg_warn("Digest algorithm \"%s\" not found: disabling TLS support", 345 props->fpt_dgst); 346 return (0); 347 } 348 349 /* 350 * Sanity check: Newer shared libraries may use larger digests. 351 */ 352 if ((md_len = EVP_MD_size(md_alg)) > EVP_MAX_MD_SIZE) { 353 msg_warn("Digest algorithm \"%s\" output size %u too large:" 354 " disabling TLS support", props->fpt_dgst, md_len); 355 return (0); 356 } 357 358 /* 359 * Initialize the PRNG (Pseudo Random Number Generator) with some seed 360 * from external and internal sources. Don't enable TLS without some real 361 * entropy. 362 */ 363 if (tls_ext_seed(var_tls_daemon_rand_bytes) < 0) { 364 msg_warn("no entropy for TLS key generation: disabling TLS support"); 365 return (0); 366 } 367 tls_int_seed(); 368 369 /* 370 * The SSL/TLS specifications require the client to send a message in the 371 * oldest specification it understands with the highest level it 372 * understands in the message. Netscape communicator can still 373 * communicate with SSLv2 servers, so it sends out a SSLv2 client hello. 374 * To deal with it, our server must be SSLv2 aware (even if we don't like 375 * SSLv2), so we need to have the SSLv23 server here. If we want to limit 376 * the protocol level, we can add an option to not use SSLv2/v3/TLSv1 377 * later. 378 */ 379 ERR_clear_error(); 380 if ((server_ctx = SSL_CTX_new(SSLv23_server_method())) == 0) { 381 msg_warn("cannot allocate server SSL_CTX: disabling TLS support"); 382 tls_print_errors(); 383 return (0); 384 } 385 386 /* 387 * See the verify callback in tls_verify.c 388 */ 389 SSL_CTX_set_verify_depth(server_ctx, props->verifydepth + 1); 390 391 /* 392 * Protocol work-arounds, OpenSSL version dependent. 393 */ 394 off |= tls_bug_bits(); 395 SSL_CTX_set_options(server_ctx, off); 396 397 /* 398 * Global protocol selection. 399 */ 400 if (protomask != 0) 401 SSL_CTX_set_options(server_ctx, 402 ((protomask & TLS_PROTOCOL_TLSv1) ? SSL_OP_NO_TLSv1 : 0L) 403 | ((protomask & TLS_PROTOCOL_TLSv1_1) ? SSL_OP_NO_TLSv1_1 : 0L) 404 | ((protomask & TLS_PROTOCOL_TLSv1_2) ? SSL_OP_NO_TLSv1_2 : 0L) 405 | ((protomask & TLS_PROTOCOL_SSLv3) ? SSL_OP_NO_SSLv3 : 0L) 406 | ((protomask & TLS_PROTOCOL_SSLv2) ? SSL_OP_NO_SSLv2 : 0L)); 407 408#if OPENSSL_VERSION_NUMBER >= 0x0090700fL 409 410 /* 411 * Some sites may want to give the client less rope. On the other hand, 412 * this could trigger inter-operability issues, the client should not 413 * offer ciphers it implements poorly, but this hasn't stopped some 414 * vendors from getting it wrong. 415 * 416 * XXX: Given OpenSSL's security history, nobody should still be using 417 * 0.9.7, let alone 0.9.6 or earlier. Warning added to TLS_README.html. 418 */ 419 if (var_tls_preempt_clist) 420 SSL_CTX_set_options(server_ctx, SSL_OP_CIPHER_SERVER_PREFERENCE); 421#endif 422 423 /* 424 * Set the call-back routine to debug handshake progress. 425 */ 426 if (props->log_level >= 2) 427 SSL_CTX_set_info_callback(server_ctx, tls_info_callback); 428 429 /* 430 * Load the CA public key certificates for both the server cert and for 431 * the verification of client certificates. As provided by OpenSSL we 432 * support two types of CA certificate handling: One possibility is to 433 * add all CA certificates to one large CAfile, the other possibility is 434 * a directory pointed to by CApath, containing separate files for each 435 * CA with softlinks named after the hash values of the certificate. The 436 * first alternative has the advantage that the file is opened and read 437 * at startup time, so that you don't have the hassle to maintain another 438 * copy of the CApath directory for chroot-jail. 439 */ 440 if (tls_set_ca_certificate_info(server_ctx, 441 props->CAfile, props->CApath) < 0) { 442 /* tls_set_ca_certificate_info() already logs a warning. */ 443 SSL_CTX_free(server_ctx); /* 200411 */ 444 return (0); 445 } 446 447 /* 448 * Load the server public key certificate and private key from file and 449 * check whether the cert matches the key. We can use RSA certificates 450 * ("cert") DSA certificates ("dcert") or ECDSA certificates ("eccert"). 451 * All three can be made available at the same time. The CA certificates 452 * for all three are handled in the same setup already finished. Which 453 * one is used depends on the cipher negotiated (that is: the first 454 * cipher listed by the client which does match the server). A client 455 * with RSA only (e.g. Netscape) will use the RSA certificate only. A 456 * client with openssl-library will use RSA first if not especially 457 * changed in the cipher setup. 458 */ 459 if (tls_set_my_certificate_key_info(server_ctx, 460 props->cert_file, 461 props->key_file, 462 props->dcert_file, 463 props->dkey_file, 464 props->eccert_file, 465 props->eckey_file) < 0) { 466 /* tls_set_my_certificate_key_info() already logs a warning. */ 467 SSL_CTX_free(server_ctx); /* 200411 */ 468 return (0); 469 } 470 471 /* 472 * According to the OpenSSL documentation, temporary RSA key is needed 473 * export ciphers are in use. We have to provide one, so well, we just do 474 * it. 475 */ 476 SSL_CTX_set_tmp_rsa_callback(server_ctx, tls_tmp_rsa_cb); 477 478 /* 479 * Diffie-Hellman key generation parameters can either be loaded from 480 * files (preferred) or taken from compiled in values. First, set the 481 * callback that will select the values when requested, then load the 482 * (possibly) available DH parameters from files. We are generous with 483 * the error handling, since we do have default values compiled in, so we 484 * will not abort but just log the error message. 485 */ 486 SSL_CTX_set_tmp_dh_callback(server_ctx, tls_tmp_dh_cb); 487 if (*props->dh1024_param_file != 0) 488 tls_set_dh_from_file(props->dh1024_param_file, 1024); 489 if (*props->dh512_param_file != 0) 490 tls_set_dh_from_file(props->dh512_param_file, 512); 491 492 /* 493 * Enable EECDH if available, errors are not fatal, we just keep going 494 * with any remaining key-exchange algorithms. 495 */ 496 (void) tls_set_eecdh_curve(server_ctx, props->eecdh_grade); 497 498 /* 499 * If we want to check client certificates, we have to indicate it in 500 * advance. By now we only allow to decide on a global basis. If we want 501 * to allow certificate based relaying, we must ask the client to provide 502 * one with SSL_VERIFY_PEER. The client now can decide, whether it 503 * provides one or not. We can enforce a failure of the negotiation with 504 * SSL_VERIFY_FAIL_IF_NO_PEER_CERT, if we do not allow a connection 505 * without one. In the "server hello" following the initialization by the 506 * "client hello" the server must provide a list of CAs it is willing to 507 * accept. Some clever clients will then select one from the list of 508 * available certificates matching these CAs. Netscape Communicator will 509 * present the list of certificates for selecting the one to be sent, or 510 * it will issue a warning, if there is no certificate matching the 511 * available CAs. 512 * 513 * With regard to the purpose of the certificate for relaying, we might like 514 * a later negotiation, maybe relaying would already be allowed for other 515 * reasons, but this would involve severe changes in the internal postfix 516 * logic, so we have to live with it the way it is. 517 */ 518 if (props->ask_ccert) 519 verify_flags = SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE; 520 SSL_CTX_set_verify(server_ctx, verify_flags, 521 tls_verify_certificate_callback); 522 if (*props->CAfile) 523 SSL_CTX_set_client_CA_list(server_ctx, 524 SSL_load_client_CA_file(props->CAfile)); 525 526 /* 527 * Initialize our own TLS server handle, before diving into the details 528 * of TLS session cache management. 529 */ 530 app_ctx = tls_alloc_app_context(server_ctx); 531 532 /* 533 * The session cache is implemented by the tlsmgr(8) server. 534 * 535 * XXX 200502 Surprise: when OpenSSL purges an entry from the in-memory 536 * cache, it also attempts to purge the entry from the on-disk cache. 537 * This is undesirable, especially when we set the in-memory cache size 538 * to 1. For this reason we don't allow OpenSSL to purge on-disk cache 539 * entries, and leave it up to the tlsmgr process instead. Found by 540 * Victor Duchovni. 541 */ 542 543 if (tls_mgr_policy(props->cache_type, &cachable) != TLS_MGR_STAT_OK) 544 cachable = 0; 545 546 if (cachable || props->set_sessid) { 547 548 /* 549 * Initialize the session cache. 550 * 551 * With a large number of concurrent smtpd(8) processes, it is not a 552 * good idea to cache multiple large session objects in each process. 553 * We set the internal cache size to 1, and don't register a 554 * "remove_cb" so as to avoid deleting good sessions from the 555 * external cache prematurely (when the internal cache is full, 556 * OpenSSL removes sessions from the external cache also)! 557 * 558 * This makes SSL_CTX_remove_session() not useful for flushing broken 559 * sessions from the external cache, so we must delete them directly 560 * (not via a callback). 561 * 562 * Set a session id context to identify to what type of server process 563 * created a session. In our case, the context is simply the name of 564 * the mail system: "Postfix/TLS". 565 */ 566 SSL_CTX_sess_set_cache_size(server_ctx, 1); 567 SSL_CTX_set_session_id_context(server_ctx, 568 (void *) &server_session_id_context, 569 sizeof(server_session_id_context)); 570 SSL_CTX_set_session_cache_mode(server_ctx, 571 SSL_SESS_CACHE_SERVER | 572 SSL_SESS_CACHE_NO_AUTO_CLEAR); 573 if (cachable) { 574 app_ctx->cache_type = mystrdup(props->cache_type); 575 576 SSL_CTX_sess_set_get_cb(server_ctx, get_server_session_cb); 577 SSL_CTX_sess_set_new_cb(server_ctx, new_server_session_cb); 578 } 579 580 /* 581 * OpenSSL ignores timed-out sessions. We need to set the internal 582 * cache timeout at least as high as the external cache timeout. This 583 * applies even if no internal cache is used. 584 */ 585 SSL_CTX_set_timeout(server_ctx, props->scache_timeout); 586 } else { 587 588 /* 589 * If we have no external cache, disable all caching. No use wasting 590 * server memory resources with sessions they are unlikely to be able 591 * to reuse. 592 */ 593 SSL_CTX_set_session_cache_mode(server_ctx, SSL_SESS_CACHE_OFF); 594 } 595 596 return (app_ctx); 597} 598 599 /* 600 * This is the actual startup routine for a new connection. We expect that 601 * the SMTP buffers are flushed and the "220 Ready to start TLS" was sent to 602 * the client, so that we can immediately start the TLS handshake process. 603 */ 604TLS_SESS_STATE *tls_server_start(const TLS_SERVER_START_PROPS *props) 605{ 606 int sts; 607 TLS_SESS_STATE *TLScontext; 608 const char *cipher_list; 609 TLS_APPL_STATE *app_ctx = props->ctx; 610 611 if (props->log_level >= 1) 612 msg_info("setting up TLS connection from %s", props->namaddr); 613 614 cipher_list = tls_set_ciphers(app_ctx, "TLS", props->cipher_grade, 615 props->cipher_exclusions); 616 if (cipher_list == 0) { 617 msg_warn("%s: %s: aborting TLS session", props->namaddr, 618 vstring_str(app_ctx->why)); 619 return (0); 620 } 621 if (props->log_level >= 2) 622 msg_info("%s: TLS cipher list \"%s\"", props->namaddr, cipher_list); 623 624 /* 625 * Allocate a new TLScontext for the new connection and get an SSL 626 * structure. Add the location of TLScontext to the SSL to later retrieve 627 * the information inside the tls_verify_certificate_callback(). 628 */ 629 TLScontext = tls_alloc_sess_context(props->log_level, props->namaddr); 630 TLScontext->cache_type = app_ctx->cache_type; 631 632 TLScontext->serverid = mystrdup(props->serverid); 633 TLScontext->am_server = 1; 634 635 TLScontext->fpt_dgst = mystrdup(props->fpt_dgst); 636 TLScontext->stream = props->stream; 637 638 ERR_clear_error(); 639 if ((TLScontext->con = (SSL *) SSL_new(app_ctx->ssl_ctx)) == 0) { 640 msg_warn("Could not allocate 'TLScontext->con' with SSL_new()"); 641 tls_print_errors(); 642 tls_free_context(TLScontext); 643 return (0); 644 } 645 if (!SSL_set_ex_data(TLScontext->con, TLScontext_index, TLScontext)) { 646 msg_warn("Could not set application data for 'TLScontext->con'"); 647 tls_print_errors(); 648 tls_free_context(TLScontext); 649 return (0); 650 } 651 652 /* 653 * Before really starting anything, try to seed the PRNG a little bit 654 * more. 655 */ 656 tls_int_seed(); 657 (void) tls_ext_seed(var_tls_daemon_rand_bytes); 658 659 /* 660 * Initialize the SSL connection to accept state. This should not be 661 * necessary anymore since 0.9.3, but the call is still in the library 662 * and maintaining compatibility never hurts. 663 */ 664 SSL_set_accept_state(TLScontext->con); 665 666 /* 667 * Connect the SSL connection with the network socket. 668 */ 669 if (SSL_set_fd(TLScontext->con, props->stream == 0 ? props->fd : 670 vstream_fileno(props->stream)) != 1) { 671 msg_info("SSL_set_fd error to %s", props->namaddr); 672 tls_print_errors(); 673 uncache_session(app_ctx->ssl_ctx, TLScontext); 674 tls_free_context(TLScontext); 675 return (0); 676 } 677 678 /* 679 * If the debug level selected is high enough, all of the data is dumped: 680 * 3 will dump the SSL negotiation, 4 will dump everything. 681 * 682 * We do have an SSL_set_fd() and now suddenly a BIO_ routine is called? 683 * Well there is a BIO below the SSL routines that is automatically 684 * created for us, so we can use it for debugging purposes. 685 */ 686 if (props->log_level >= 3) 687 BIO_set_callback(SSL_get_rbio(TLScontext->con), tls_bio_dump_cb); 688 689 /* 690 * If we don't trigger the handshake in the library, leave control over 691 * SSL_accept/read/write/etc with the application. 692 */ 693 if (props->stream == 0) 694 return (TLScontext); 695 696 /* 697 * Turn on non-blocking I/O so that we can enforce timeouts on network 698 * I/O. 699 */ 700 non_blocking(vstream_fileno(props->stream), NON_BLOCKING); 701 702 /* 703 * Start TLS negotiations. This process is a black box that invokes our 704 * call-backs for session caching and certificate verification. 705 * 706 * Error handling: If the SSL handhake fails, we print out an error message 707 * and remove all TLS state concerning this session. 708 */ 709 sts = tls_bio_accept(vstream_fileno(props->stream), props->timeout, 710 TLScontext); 711 if (sts <= 0) { 712 msg_info("SSL_accept error from %s: %d", props->namaddr, sts); 713 tls_print_errors(); 714 tls_free_context(TLScontext); 715 return (0); 716 } 717 return (tls_server_post_accept(TLScontext)); 718} 719 720/* tls_server_post_accept - post-handshake processing */ 721 722TLS_SESS_STATE *tls_server_post_accept(TLS_SESS_STATE *TLScontext) 723{ 724 const SSL_CIPHER *cipher; 725 X509 *peer; 726 char buf[CCERT_BUFSIZ]; 727 728 /* Only loglevel==4 dumps everything */ 729 if (TLScontext->log_level < 4) 730 BIO_set_callback(SSL_get_rbio(TLScontext->con), 0); 731 732 /* 733 * The caller may want to know if this session was reused or if a new 734 * session was negotiated. 735 */ 736 TLScontext->session_reused = SSL_session_reused(TLScontext->con); 737 if (TLScontext->log_level >= 2 && TLScontext->session_reused) 738 msg_info("%s: Reusing old session", TLScontext->namaddr); 739 740 /* 741 * Let's see whether a peer certificate is available and what is the 742 * actual information. We want to save it for later use. 743 */ 744 peer = SSL_get_peer_certificate(TLScontext->con); 745 if (peer != NULL) { 746 TLScontext->peer_status |= TLS_CERT_FLAG_PRESENT; 747 if (SSL_get_verify_result(TLScontext->con) == X509_V_OK) 748 TLScontext->peer_status |= TLS_CERT_FLAG_TRUSTED; 749 750 if (TLScontext->log_level >= 2) { 751 X509_NAME_oneline(X509_get_subject_name(peer), 752 buf, sizeof(buf)); 753 msg_info("subject=%s", buf); 754 X509_NAME_oneline(X509_get_issuer_name(peer), 755 buf, sizeof(buf)); 756 msg_info("issuer=%s", buf); 757 } 758 TLScontext->peer_CN = tls_peer_CN(peer, TLScontext); 759 TLScontext->issuer_CN = tls_issuer_CN(peer, TLScontext); 760 TLScontext->peer_fingerprint = 761 tls_fingerprint(peer, TLScontext->fpt_dgst); 762 763 if (TLScontext->log_level >= 1) { 764 msg_info("%s: %s: subject_CN=%s, issuer=%s, fingerprint=%s", 765 TLScontext->namaddr, 766 TLS_CERT_IS_TRUSTED(TLScontext) ? "Trusted" : "Untrusted", 767 TLScontext->peer_CN, TLScontext->issuer_CN, 768 TLScontext->peer_fingerprint); 769 } 770 X509_free(peer); 771 } else { 772 TLScontext->peer_CN = mystrdup(""); 773 TLScontext->issuer_CN = mystrdup(""); 774 TLScontext->peer_fingerprint = mystrdup(""); 775 } 776 777 /* 778 * Finally, collect information about protocol and cipher for logging 779 */ 780 TLScontext->protocol = SSL_get_version(TLScontext->con); 781 cipher = SSL_get_current_cipher(TLScontext->con); 782 TLScontext->cipher_name = SSL_CIPHER_get_name(cipher); 783 TLScontext->cipher_usebits = SSL_CIPHER_get_bits(cipher, 784 &(TLScontext->cipher_algbits)); 785 786 /* 787 * If the library triggered the SSL handshake, switch to the 788 * tls_timed_read/write() functions and make the TLScontext available to 789 * those functions. Otherwise, leave control over SSL_read/write/etc. 790 * with the application. 791 */ 792 if (TLScontext->stream != 0) 793 tls_stream_start(TLScontext->stream, TLScontext); 794 795 /* 796 * All the key facts in a single log entry. 797 */ 798 if (TLScontext->log_level >= 1) 799 msg_info("%s TLS connection established from %s: %s with cipher %s " 800 "(%d/%d bits)", !TLS_CERT_IS_PRESENT(TLScontext) ? "Anonymous" 801 : TLS_CERT_IS_TRUSTED(TLScontext) ? "Trusted" : "Untrusted", 802 TLScontext->namaddr, TLScontext->protocol, TLScontext->cipher_name, 803 TLScontext->cipher_usebits, TLScontext->cipher_algbits); 804 805 tls_int_seed(); 806 807 return (TLScontext); 808} 809 810#endif /* USE_TLS */ 811