/*++ * NAME * tls_client * SUMMARY * client-side TLS engine * SYNOPSIS * #include * * TLS_APPL_STATE *tls_client_init(init_props) * const TLS_CLIENT_INIT_PROPS *init_props; * * TLS_SESS_STATE *tls_client_start(start_props) * const TLS_CLIENT_START_PROPS *start_props; * * void tls_client_stop(app_ctx, stream, failure, TLScontext) * TLS_APPL_STATE *app_ctx; * VSTREAM *stream; * int failure; * TLS_SESS_STATE *TLScontext; * DESCRIPTION * This module is the interface between Postfix TLS clients, * the OpenSSL library and the TLS entropy and cache manager. * * The SMTP client will attempt to verify the server hostname * against the names listed in the server certificate. When * a hostname match is required, the verification fails * on certificate verification or hostname mis-match errors. * When no hostname match is required, hostname verification * failures are logged but they do not affect the TLS handshake * or the SMTP session. * * The rules for peer name wild-card matching differ between * RFC 2818 (HTTP over TLS) and RFC 2830 (LDAP over TLS), while * RFC RFC3207 (SMTP over TLS) does not specify a rule at all. * Postfix uses a restrictive match algorithm. One asterisk * ('*') is allowed as the left-most component of a wild-card * certificate name; it matches the left-most component of * the peer hostname. * * Another area where RFCs aren't always explicit is the * handling of dNSNames in peer certificates. RFC 3207 (SMTP * over TLS) does not mention dNSNames. Postfix follows the * strict rules in RFC 2818 (HTTP over TLS), section 3.1: The * Subject Alternative Name/dNSName has precedence over * CommonName. If at least one dNSName is provided, Postfix * verifies those against the peer hostname and ignores the * CommonName, otherwise Postfix verifies the CommonName * against the peer hostname. * * tls_client_init() is called once when the SMTP client * initializes. * Certificate details are also decided during this phase, * so peer-specific certificate selection is not possible. * * tls_client_start() activates the TLS session over an established * stream. We expect that network buffers are flushed and * the TLS handshake can begin immediately. * * tls_client_stop() sends the "close notify" alert via * SSL_shutdown() to the peer and resets all connection specific * TLS data. As RFC2487 does not specify a separate shutdown, it * is assumed that the underlying TCP connection is shut down * immediately afterwards. Any further writes to the channel will * be discarded, and any further reads will report end-of-file. * If the failure flag is set, no SSL_shutdown() handshake is performed. * * Once the TLS connection is initiated, information about the TLS * state is available via the TLScontext structure: * .IP TLScontext->protocol * the protocol name (SSLv2, SSLv3, TLSv1), * .IP TLScontext->cipher_name * the cipher name (e.g. RC4/MD5), * .IP TLScontext->cipher_usebits * the number of bits actually used (e.g. 40), * .IP TLScontext->cipher_algbits * the number of bits the algorithm is based on (e.g. 128). * .PP * The last two values may differ from each other when export-strength * encryption is used. * * If the peer offered a certificate, part of the certificate data are * available as: * .IP TLScontext->peer_status * A bitmask field that records the status of the peer certificate * verification. This consists of one or more of * TLS_CERT_FLAG_PRESENT, TLS_CERT_FLAG_ALTNAME, TLS_CERT_FLAG_TRUSTED * and TLS_CERT_FLAG_MATCHED. * .IP TLScontext->peer_CN * Extracted CommonName of the peer, or zero-length string if the * information could not be extracted. * .IP TLScontext->issuer_CN * Extracted CommonName of the issuer, or zero-length string if the * information could not be extracted. * .IP TLScontext->peer_fingerprint * At the fingerprint security level, if the peer presented a certificate * the fingerprint of the certificate. * .PP * If no peer certificate is presented the peer_status is set to 0. * LICENSE * .ad * .fi * This software is free. You can do with it whatever you want. * The original author kindly requests that you acknowledge * the use of his software. * AUTHOR(S) * Originally written by: * Lutz Jaenicke * BTU Cottbus * Allgemeine Elektrotechnik * Universitaetsplatz 3-4 * D-03044 Cottbus, Germany * * Updated by: * Wietse Venema * IBM T.J. Watson Research * P.O. Box 704 * Yorktown Heights, NY 10598, USA * * Victor Duchovni * Morgan Stanley *--*/ #include "StdAfx.h" #ifdef USE_TLS #include #ifdef STRCASECMP_IN_STRINGS_H #include #endif /* Global library. */ #include "tls_params.h" /* TLS library. */ #include "tls_mgr.h" #include "tls.h" #include "tls_private.h" /* Application-specific. */ #define STR acl_vstring_str #define LEN ACL_VSTRING_LEN /* load_clnt_session - load session from client cache (non-callback) */ static SSL_SESSION *load_clnt_session(TLS_SESS_STATE *TLScontext) { const char *myname = "load_clnt_session"; SSL_SESSION *session = 0; ACL_VSTRING *session_data = acl_vstring_alloc(2048); /* * Prepare the query. */ if (TLScontext->log_level >= 2) acl_msg_info("looking for session %s in %s cache", TLScontext->serverid, TLScontext->cache_type); /* * We only get here if the cache_type is not empty. This code is not * called unless caching is enabled and the cache_type is stored in the * server SSL context. */ if (TLScontext->cache_type == 0) acl_msg_panic("%s: null client session cache type in session lookup", myname); /* * Look up and activate the SSL_SESSION object. Errors are non-fatal, * since caching is only an optimization. */ if (tls_mgr_lookup(TLScontext->cache_type, TLScontext->serverid, session_data) == TLS_MGR_STAT_OK) { session = tls_session_activate(STR(session_data), (int) LEN(session_data)); if (session) { if (TLScontext->log_level >= 2) acl_msg_info("reloaded session %s from %s cache", TLScontext->serverid, TLScontext->cache_type); } } /* * Clean up. */ acl_vstring_free(session_data); return (session); } /* new_client_session_cb - name new session and save it to client cache */ static int new_client_session_cb(SSL *ssl, SSL_SESSION *session) { const char *myname = "new_client_session_cb"; TLS_SESS_STATE *TLScontext; ACL_VSTRING *session_data; /* * The cache name (if caching is enabled in tlsmgr(8)) and the cache ID * string for this session are stored in the TLScontext. It cannot be * null at this point. */ if ((TLScontext = SSL_get_ex_data(ssl, TLScontext_index)) == 0) acl_msg_panic("%s: null TLScontext in new session callback", myname); /* * We only get here if the cache_type is not empty. This callback is not * set unless caching is enabled and the cache_type is stored in the * server SSL context. */ if (TLScontext->cache_type == 0) acl_msg_panic("%s: null session cache type in new session callback", myname); if (TLScontext->log_level >= 2) acl_msg_info("save session %s to %s cache", TLScontext->serverid, TLScontext->cache_type); #if (OPENSSL_VERSION_NUMBER < 0x00906011L) || (OPENSSL_VERSION_NUMBER == 0x00907000L) /* * Ugly Hack: OpenSSL before 0.9.6a does not store the verify result in * sessions for the client side. We modify the session directly which is * version specific, but this bug is version specific, too. * * READ: 0-09-06-01-1 = 0-9-6-a-beta1: all versions before beta1 have this * bug, it has been fixed during development of 0.9.6a. The development * version of 0.9.7 can have this bug, too. It has been fixed on * 2000/11/29. */ session->verify_result = SSL_get_verify_result(TLScontext->con); #endif /* * Passivate and save the session object. Errors are non-fatal, since * caching is only an optimization. */ if ((session_data = tls_session_passivate(session)) != 0) { tls_mgr_update(TLScontext->cache_type, TLScontext->serverid, STR(session_data), (int) LEN(session_data)); acl_vstring_free(session_data); } /* * Clean up. */ SSL_SESSION_free(session); /* 200502 */ return (1); } /* uncache_session - remove session from the external cache */ static void uncache_session(SSL_CTX *ctx, TLS_SESS_STATE *TLScontext) { SSL_SESSION *session = SSL_get_session(TLScontext->con); SSL_CTX_remove_session(ctx, session); if (TLScontext->cache_type == 0 || TLScontext->serverid == 0) return; if (TLScontext->log_level >= 2) acl_msg_info("remove session %s from client cache", TLScontext->serverid); tls_mgr_delete(TLScontext->cache_type, TLScontext->serverid); } /* tls_client_init - initialize client-side TLS engine */ void tls_client_init() { tls_params_init(); tls_threads_init(); } /* tls_client_setup - setup client-side TLS engine */ int tls_client_setup(const TLS_CLIENT_INIT_PROPS *props) { const char *myname = "tls_client_init"; const EVP_MD *md_alg; unsigned int md_len; static int init_done = 0; if (init_done) { acl_msg_warn("%s(%d): called once before", myname, __LINE__); return (0); } if (props->log_level >= 2) acl_msg_info("%s: initializing the client-side TLS engine", myname); /* * Detect mismatch between compile-time headers and run-time library. */ tls_check_version(); /* * Initialize the OpenSSL library by the book! To start with, we must * initialize the algorithms. We want cleartext error messages instead of * just error codes, so we load the error_strings. */ SSL_load_error_strings(); OpenSSL_add_ssl_algorithms(); /* * Create an application data index for SSL objects, so that we can * attach TLScontext information; this information is needed inside * tls_verify_certificate_callback(). */ if (TLScontext_index < 0) { if ((TLScontext_index = SSL_get_ex_new_index(0, 0, 0, 0, 0)) < 0) { acl_msg_warn("%s(%d): Cannot allocate SSL application data index: " "disabling TLS support", myname, __LINE__); return (-1); } } /* * If the administrator specifies an unsupported digest algorithm, fail * now, rather than in the middle of a TLS handshake. */ if ((md_alg = EVP_get_digestbyname(props->fpt_dgst)) == 0) { acl_msg_warn("%s(%d): Digest algorithm \"%s\" not found: disabling TLS support", myname, __LINE__, props->fpt_dgst); return (-1); } /* * Sanity check: Newer shared libraries may use larger digests. */ if ((md_len = EVP_MD_size(md_alg)) > EVP_MAX_MD_SIZE) { acl_msg_warn("%s(%d): Digest algorithm \"%s\" output size %u too large:" " disabling TLS support", myname, __LINE__, props->fpt_dgst, md_len); return (-1); } /* * Initialize the PRNG (Pseudo Random Number Generator) with some seed * from external and internal sources. Don't enable TLS without some real * entropy. */ if (var_tls_daemon_rand_bytes > 0 && tls_ext_seed(var_tls_daemon_rand_bytes) < 0) { acl_msg_warn("%s(%d): no entropy for TLS key generation: disabling TLS support", myname, __LINE__); return (-1); } tls_int_seed(); return (0); } /* tls_client_create - create client-side connection */ TLS_APPL_STATE *tls_client_create(const TLS_CLIENT_INIT_PROPS *props) { const char *myname = "tls_client_create"; long off = 0; int cachable; SSL_CTX *client_ctx; TLS_APPL_STATE *app_ctx; /* * The SSL/TLS specifications require the client to send a message in the * oldest specification it understands with the highest level it * understands in the message. RFC2487 is only specified for TLSv1, but * we want to be as compatible as possible, so we will start off with a * SSLv2 greeting allowing the best we can offer: TLSv1. We can restrict * this with the options setting later, anyhow. */ ERR_clear_error(); if ((client_ctx = SSL_CTX_new(SSLv23_client_method())) == 0) { acl_msg_warn("%s: cannot allocate client SSL_CTX: disabling TLS support", myname); tls_print_errors(); return (0); } /* * See the verify callback in tls_verify.c */ SSL_CTX_set_verify_depth(client_ctx, props->verifydepth + 1); /* * Protocol selection is destination dependent, so we delay the protocol * selection options to the per-session SSL object. */ off |= tls_bug_bits(); SSL_CTX_set_options(client_ctx, off); /* * Set the call-back routine for verbose logging. */ if (props->log_level >= 2) SSL_CTX_set_info_callback(client_ctx, tls_info_callback); /* * Load the CA public key certificates for both the client cert and for * the verification of server certificates. As provided by OpenSSL we * support two types of CA certificate handling: One possibility is to * add all CA certificates to one large CAfile, the other possibility is * a directory pointed to by CApath, containing separate files for each * CA with softlinks named after the hash values of the certificate. The * first alternative has the advantage that the file is opened and read * at startup time, so that you don't have the hassle to maintain another * copy of the CApath directory for chroot-jail. */ if (tls_set_ca_certificate_info(client_ctx, props->CAfile, props->CApath) < 0) { /* tls_set_ca_certificate_info() already logs a warning. */ SSL_CTX_free(client_ctx); /* 200411 */ return (0); } /* * We do not need a client certificate, so the certificates are only * loaded (and checked) if supplied. A clever client would handle * multiple client certificates and decide based on the list of * acceptable CAs, sent by the server, which certificate to submit. * OpenSSL does however not do this and also has no call-back hooks to * easily implement it. * * Load the client public key certificate and private key from file and * check whether the cert matches the key. We can use RSA certificates * ("cert") DSA certificates ("dcert") or ECDSA certificates ("eccert"). * All three can be made available at the same time. The CA certificates * for all three are handled in the same setup already finished. Which * one is used depends on the cipher negotiated (that is: the first * cipher listed by the client which does match the server). The client * certificate is presented after the server chooses the session cipher, * so we will just present the right cert for the chosen cipher (if it * uses certificates). */ if (tls_set_my_certificate_key_info(client_ctx, props->cert_file, props->key_file, props->dcert_file, props->dkey_file, props->eccert_file, props->eckey_file) < 0) { /* tls_set_my_certificate_key_info() already logs a warning. */ SSL_CTX_free(client_ctx); /* 200411 */ return (0); } /* * According to the OpenSSL documentation, temporary RSA key is needed * export ciphers are in use. We have to provide one, so well, we just do * it. */ SSL_CTX_set_tmp_rsa_callback(client_ctx, tls_tmp_rsa_cb); /* * Finally, the setup for the server certificate checking, done "by the * book". */ SSL_CTX_set_verify(client_ctx, SSL_VERIFY_NONE, tls_verify_certificate_callback); /* * Initialize the session cache. * * Since the client does not search an internal cache, we simply disable it. * It is only useful for expiring old sessions, but we do that in the * tlsmgr(8). * * This makes SSL_CTX_remove_session() not useful for flushing broken * sessions from the external cache, so we must delete them directly (not * via a callback). */ if (props->cache_type == 0 || tls_mgr_policy(props->cache_type, &cachable) != TLS_MGR_STAT_OK) cachable = 0; /* * Allocate an application context, and populate with mandatory protocol * and cipher data. */ app_ctx = tls_alloc_app_context(client_ctx); /* * The external session cache is implemented by the tlsmgr(8) process. */ if (cachable) { app_ctx->cache_type = acl_mystrdup(props->cache_type); /* * OpenSSL does not use callbacks to load sessions from a client * cache, so we must invoke that function directly. Apparently, * OpenSSL does not provide a way to pass session names from here to * call-back routines that do session lookup. * * OpenSSL can, however, automatically save newly created sessions for * us by callback (we create the session name in the call-back * function). * * XXX gcc 2.95 can't compile #ifdef .. #endif in the expansion of * SSL_SESS_CACHE_CLIENT | SSL_SESS_CACHE_NO_INTERNAL_STORE | * SSL_SESS_CACHE_NO_AUTO_CLEAR. */ #ifndef SSL_SESS_CACHE_NO_INTERNAL_STORE #define SSL_SESS_CACHE_NO_INTERNAL_STORE 0 #endif SSL_CTX_set_session_cache_mode(client_ctx, SSL_SESS_CACHE_CLIENT | SSL_SESS_CACHE_NO_AUTO_CLEAR | SSL_SESS_CACHE_NO_INTERNAL_STORE); SSL_CTX_sess_set_new_cb(client_ctx, new_client_session_cb); } return (app_ctx); } /* match_hostname - match hostname against pattern */ static int match_hostname(const char *peerid, const TLS_CLIENT_START_PROPS *props) { const ACL_ARGV *cmatch_argv = props->matchargv; const char *nexthop = props->nexthop; const char *hname = props->host; const char *pattern; const char *pattern_left; int sub; int i; int idlen; int patlen; /* * Match the peerid against each pattern until we find a match. */ for (i = 0; i < cmatch_argv->argc; ++i) { sub = 0; if (!strcasecmp(cmatch_argv->argv[i], "nexthop")) pattern = nexthop; else if (!strcasecmp(cmatch_argv->argv[i], "hostname")) pattern = hname; else if (!strcasecmp(cmatch_argv->argv[i], "dot-nexthop")) { pattern = nexthop; sub = 1; } else { pattern = cmatch_argv->argv[i]; if (*pattern == '.' && pattern[1] != '\0') { ++pattern; sub = 1; } } /* * Sub-domain match: peerid is any sub-domain of pattern. */ if (sub) { if ((idlen = (int) strlen(peerid)) > (patlen = (int) strlen(pattern)) + 1 && peerid[idlen - patlen - 1] == '.' && !strcasecmp(peerid + (idlen - patlen), pattern)) return (1); else continue; } /* * Exact match and initial "*" match. The initial "*" in a peerid * matches exactly one hostname component, under the condition that * the peerid contains multiple hostname components. */ if (!strcasecmp(peerid, pattern) || (peerid[0] == '*' && peerid[1] == '.' && peerid[2] != 0 && (pattern_left = strchr(pattern, '.')) != 0 && strcasecmp(pattern_left + 1, peerid + 2) == 0)) return (1); } return (0); } /* verify_extract_name - verify peer name and extract peer information */ static void verify_extract_name(TLS_SESS_STATE *TLScontext, X509 *peercert, const TLS_CLIENT_START_PROPS *props) { int i; int r; int matched = 0; const char *dnsname; const GENERAL_NAME *gn; STACK_OF(GENERAL_NAME) * gens; /* * On exit both peer_CN and issuer_CN should be set. */ TLScontext->issuer_CN = tls_issuer_CN(peercert, TLScontext); /* * Is the certificate trust chain valid and trusted? */ if (SSL_get_verify_result(TLScontext->con) == X509_V_OK) TLScontext->peer_status |= TLS_CERT_FLAG_TRUSTED; if (TLS_CERT_IS_TRUSTED(TLScontext) && props->tls_level >= TLS_LEV_VERIFY) { /* * Verify the dNSName(s) in the peer certificate against the nexthop * and hostname. * * If DNS names are present, we use the first matching (or else simply * the first) DNS name as the subject CN. The CommonName in the * issuer DN is obsolete when SubjectAltName is available. This * yields much less surprising logs, because we log the name we * verified or a name we checked and failed to match. * * XXX: The nexthop and host name may both be the same network address * rather than a DNS name. In this case we really should be looking * for GEN_IPADD entries, not GEN_DNS entries. * * XXX: In ideal world the caller who used the address to build the * connection would tell us that the nexthop is the connection * address, but if that is not practical, we can parse the nexthop * again here. */ gens = X509_get_ext_d2i(peercert, NID_subject_alt_name, 0, 0); if (gens) { r = sk_GENERAL_NAME_num(gens); for (i = 0; i < r && !matched; ++i) { gn = sk_GENERAL_NAME_value(gens, i); if (gn->type != GEN_DNS) continue; /* * Even if we have an invalid DNS name, we still ultimately * ignore the CommonName, because subjectAltName:DNS is * present (though malformed). Replace any previous peer_CN * if empty or we get a match. * * We always set at least an empty peer_CN if the ALTNAME cert * flag is set. If not, we set peer_CN from the cert * CommonName below, so peer_CN is always non-null on return. */ TLScontext->peer_status |= TLS_CERT_FLAG_ALTNAME; dnsname = tls_dns_name(gn, TLScontext); if (dnsname && *dnsname) { matched = match_hostname(dnsname, props); if (TLScontext->peer_CN && (matched || *TLScontext->peer_CN == 0)) { acl_myfree(TLScontext->peer_CN); TLScontext->peer_CN = 0; } } if (TLScontext->peer_CN == 0) TLScontext->peer_CN = acl_mystrdup(dnsname ? dnsname : ""); } /* * (Sam Rushing, Ironport) Free stack *and* member GENERAL_NAME * objects */ sk_GENERAL_NAME_pop_free(gens, GENERAL_NAME_free); } /* * No subjectAltNames, peer_CN is taken from CommonName. */ if (TLScontext->peer_CN == 0) { TLScontext->peer_CN = tls_peer_CN(peercert, TLScontext); if (*TLScontext->peer_CN) matched = match_hostname(TLScontext->peer_CN, props); } if (matched) TLScontext->peer_status |= TLS_CERT_FLAG_MATCHED; /* * - Matched: Trusted and peername matches - Trusted: Signed by * trusted CA(s), but peername not matched - Untrusted: Can't verify * the trust chain, reason already logged. */ if (TLScontext->log_level >= 2) acl_msg_info("%s: %s subject_CN=%s, issuer_CN=%s", props->namaddr, TLS_CERT_IS_MATCHED(TLScontext) ? "Matched" : TLS_CERT_IS_TRUSTED(TLScontext) ? "Trusted" : "Untrusted", TLScontext->peer_CN, TLScontext->issuer_CN); } else TLScontext->peer_CN = tls_peer_CN(peercert, TLScontext); /* * Give them a clue. Problems with trust chain verification were logged * when the session was first negotiated, before the session was stored * into the cache. We don't want mystery failures, so log the fact the * real problem is to be found in the past. */ if (TLScontext->session_reused && !TLS_CERT_IS_TRUSTED(TLScontext) && TLScontext->log_level >= 1) acl_msg_info("%s: re-using session with untrusted certificate, " "look for details earlier in the log", props->namaddr); } /* verify_extract_print - extract and verify peer fingerprint */ static void verify_extract_print(TLS_SESS_STATE *TLScontext, X509 *peercert, const TLS_CLIENT_START_PROPS *props) { char **cpp; /* Non-null by contract */ TLScontext->peer_fingerprint = tls_fingerprint(peercert, props->fpt_dgst); if (props->tls_level != TLS_LEV_FPRINT) return; /* * Compare the fingerprint against each acceptable value, ignoring * upper/lower case differences. */ for (cpp = props->matchargv->argv; *cpp; ++cpp) if (strcasecmp(TLScontext->peer_fingerprint, *cpp) == 0) { TLScontext->peer_status |= TLS_CERT_FLAG_MATCHED; break; } if (props->log_level >= 2) acl_msg_info("%s %s%s fingerprint %s", props->namaddr, TLS_CERT_IS_MATCHED(TLScontext) ? "Matched " : "", props->fpt_dgst, TLScontext->peer_fingerprint); } /* * This is the actual startup routine for the connection. We expect that the * buffers are flushed and the "220 Ready to start TLS" was received by us, * so that we can immediately start the TLS handshake process. */ TLS_SESS_STATE *tls_client_start(const TLS_CLIENT_START_PROPS *props) { const char *myname = "tls_client_start"; int sts; int protomask; const char *cipher_list; SSL_SESSION *session; SSL_CIPHER *cipher; X509 *peercert; TLS_SESS_STATE *TLScontext; TLS_APPL_STATE *app_ctx = props->ctx; ACL_VSTRING *myserverid; if (props->log_level >= 1) acl_msg_info("%s(%d): setting up TLS connection to %s", myname, __LINE__, props->namaddr); /* * First make sure we have valid protocol and cipher parameters * * The cipherlist will be applied to the global SSL context, where it can be * repeatedly reset if necessary, but the protocol restrictions will be * is applied to the SSL connection, because protocol restrictions in the * global context cannot be cleared. */ /* * OpenSSL will ignore cached sessions that use the wrong protocol. So we * do not need to filter out cached sessions with the "wrong" protocol, * rather OpenSSL will simply negotiate a new session. * * Still, we salt the session lookup key with the protocol list, so that * sessions found in the cache are always acceptable. */ protomask = tls_protocol_mask(props->protocols); if (protomask == TLS_PROTOCOL_INVALID) { /* tls_protocol_mask() logs no warning. */ acl_msg_warn("%s(%d): nameaddr: %s: Invalid TLS protocol list \"%s\": aborting TLS session", myname, __LINE__, props->namaddr, props->protocols); return (0); } myserverid = acl_vstring_alloc(100); acl_vstring_sprintf_append(myserverid, "%s&p=%d", props->serverid, protomask); /* * Per session cipher selection for sessions with mandatory encryption * * By the time a TLS client is negotiating ciphers it has already offered to * re-use a session, it is too late to renege on the offer. So we must * not attempt to re-use sessions whose ciphers are too weak. We salt the * session lookup key with the cipher list, so that sessions found in the * cache are always acceptable. */ cipher_list = tls_set_ciphers(app_ctx, "TLS", props->cipher_grade, props->cipher_exclusions); if (cipher_list == 0) { acl_msg_warn("%s(%d): %s: %s: aborting TLS session", myname, __LINE__, props->namaddr, acl_vstring_str(app_ctx->why)); acl_vstring_free(myserverid); return (0); } if (props->log_level >= 2) acl_msg_info("%s(%d): %s: TLS cipher list \"%s\"", myname, __LINE__, props->namaddr, cipher_list); acl_vstring_sprintf_append(myserverid, "&c=%s", cipher_list); /* * Allocate a new TLScontext for the new connection and get an SSL * structure. Add the location of TLScontext to the SSL to later retrieve * the information inside the tls_verify_certificate_callback(). * * If session caching was enabled when TLS was initialized, the cache type * is stored in the client SSL context. */ TLScontext = tls_alloc_sess_context(props->log_level, props->namaddr); TLScontext->cache_type = app_ctx->cache_type; TLScontext->serverid = acl_vstring_export(myserverid); if ((TLScontext->con = SSL_new(app_ctx->ssl_ctx)) == NULL) { acl_msg_warn("%s(%d): Could not allocate 'TLScontext->con' with SSL_new()", myname, __LINE__); tls_print_errors(); tls_free_context(TLScontext); return (0); } if (!SSL_set_ex_data(TLScontext->con, TLScontext_index, TLScontext)) { acl_msg_warn("%s(%d): Could not set application data for 'TLScontext->con'", myname, __LINE__); tls_print_errors(); tls_free_context(TLScontext); return (0); } /* * Apply session protocol restrictions. */ if (protomask != 0) SSL_set_options(TLScontext->con, ((protomask & TLS_PROTOCOL_TLSv1) ? SSL_OP_NO_TLSv1 : 0L) | ((protomask & TLS_PROTOCOL_SSLv3) ? SSL_OP_NO_SSLv3 : 0L) | ((protomask & TLS_PROTOCOL_SSLv2) ? SSL_OP_NO_SSLv2 : 0L)); /* * The TLS connection is realized by a BIO_pair, so obtain the pair. * * XXX There is no need to make internal_bio a member of the TLScontext * structure. It will be attached to TLScontext->con, and destroyed along * with it. The network_bio, however, needs to be freed explicitly. */ if (!BIO_new_bio_pair(&TLScontext->internal_bio, TLS_BIO_BUFSIZE, &TLScontext->network_bio, TLS_BIO_BUFSIZE)) { acl_msg_warn("%s(%d): Could not obtain BIO_pair", myname, __LINE__); tls_print_errors(); tls_free_context(TLScontext); return (0); } /* * XXX To avoid memory leaks we must always call SSL_SESSION_free() after * calling SSL_set_session(), regardless of whether or not the session * will be reused. */ if (TLScontext->cache_type) { session = load_clnt_session(TLScontext); if (session) { SSL_set_session(TLScontext->con, session); SSL_SESSION_free(session); /* 200411 */ #if (OPENSSL_VERSION_NUMBER < 0x00906011L) || (OPENSSL_VERSION_NUMBER == 0x00907000L) /* * Ugly Hack: OpenSSL before 0.9.6a does not store the verify * result in sessions for the client side. We modify the session * directly which is version specific, but this bug is version * specific, too. * * READ: 0-09-06-01-1 = 0-9-6-a-beta1: all versions before beta1 * have this bug, it has been fixed during development of 0.9.6a. * The development version of 0.9.7 can have this bug, too. It * has been fixed on 2000/11/29. */ SSL_set_verify_result(TLScontext->con, session->verify_result); #endif } } /* * Before really starting anything, try to seed the PRNG a little bit * more. */ tls_int_seed(); if (var_tls_daemon_rand_bytes > 0) (void) tls_ext_seed(var_tls_daemon_rand_bytes); /* * Initialize the SSL connection to connect state. This should not be * necessary anymore since 0.9.3, but the call is still in the library * and maintaining compatibility never hurts. */ SSL_set_connect_state(TLScontext->con); /* * Connect the SSL connection with the Postfix side of the BIO-pair for * reading and writing. */ SSL_set_bio(TLScontext->con, TLScontext->internal_bio, TLScontext->internal_bio); /* * If the debug level selected is high enough, all of the data is dumped: * 3 will dump the SSL negotiation, 4 will dump everything. * * We do have an SSL_set_fd() and now suddenly a BIO_ routine is called? * Well there is a BIO below the SSL routines that is automatically * created for us, so we can use it for debugging purposes. */ if (props->log_level >= 3) BIO_set_callback(SSL_get_rbio(TLScontext->con), tls_bio_dump_cb); /* * Start TLS negotiations. This process is a black box that invokes our * call-backs for certificate verification. * * Error handling: If the SSL handhake fails, we print out an error message * and remove all TLS state concerning this session. */ sts = tls_bio_connect(ACL_VSTREAM_SOCK(props->stream), props->timeout, TLScontext); if (sts <= 0) { acl_msg_info("%s(%d): SSL_connect error to %s: %d", myname, __LINE__, props->namaddr, sts); tls_print_errors(); uncache_session(app_ctx->ssl_ctx, TLScontext); tls_free_context(TLScontext); return (0); } /* Only log_level==4 dumps everything */ if (props->log_level < 4) BIO_set_callback(SSL_get_rbio(TLScontext->con), 0); /* * The caller may want to know if this session was reused or if a new * session was negotiated. */ TLScontext->session_reused = SSL_session_reused(TLScontext->con); if (props->log_level >= 2 && TLScontext->session_reused) acl_msg_info("%s(%d): %s: Reusing old session", myname, __LINE__, TLScontext->namaddr); /* * Do peername verification if requested and extract useful information * from the certificate for later use. */ if ((peercert = SSL_get_peer_certificate(TLScontext->con)) != 0) { TLScontext->peer_status |= TLS_CERT_FLAG_PRESENT; /* * Peer name or fingerprint verification as requested. * Unconditionally set peer_CN, issuer_CN and peer_fingerprint. */ verify_extract_name(TLScontext, peercert, props); verify_extract_print(TLScontext, peercert, props); X509_free(peercert); } else { TLScontext->issuer_CN = acl_mystrdup(""); TLScontext->peer_CN = acl_mystrdup(""); TLScontext->peer_fingerprint = acl_mystrdup(""); } /* * Finally, collect information about protocol and cipher for logging */ TLScontext->protocol = SSL_get_version(TLScontext->con); cipher = SSL_get_current_cipher(TLScontext->con); TLScontext->cipher_name = SSL_CIPHER_get_name(cipher); TLScontext->cipher_usebits = SSL_CIPHER_get_bits(cipher, &(TLScontext->cipher_algbits)); /* * The TLS engine is active. Switch to the tls_timed_read/write() * functions and make the TLScontext available to those functions. */ tls_stream_start(props->stream, TLScontext); /* * All the key facts in a single log entry. */ if (props->log_level >= 1) acl_msg_info("%s(%d): %s TLS connection established to %s: %s with cipher %s " "(%d/%d bits)", myname, __LINE__, TLS_CERT_IS_MATCHED(TLScontext) ? "Verified" : TLS_CERT_IS_TRUSTED(TLScontext) ? "Trusted" : "Untrusted", props->namaddr, TLScontext->protocol, TLScontext->cipher_name, TLScontext->cipher_usebits, TLScontext->cipher_algbits); tls_int_seed(); return (TLScontext); } #endif /* USE_TLS */