1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
9 library. It is #included into the tls.c file when that library is used. The
10 code herein is based on a patch that was originally contributed by Steve
11 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
13 No cryptographic code is included in Exim. All this module does is to call
14 functions from the OpenSSL library. */
19 #include <openssl/lhash.h>
20 #include <openssl/ssl.h>
21 #include <openssl/err.h>
22 #include <openssl/rand.h>
23 #ifdef EXPERIMENTAL_OCSP
24 #include <openssl/ocsp.h>
27 #ifdef EXPERIMENTAL_OCSP
28 #define EXIM_OCSP_SKEW_SECONDS (300L)
29 #define EXIM_OCSP_MAX_AGE (-1L)
32 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
33 #define EXIM_HAVE_OPENSSL_TLSEXT
36 /* Structure for collecting random data for seeding. */
38 typedef struct randstuff {
43 /* Local static variables */
45 static BOOL client_verify_callback_called = FALSE;
46 static BOOL server_verify_callback_called = FALSE;
47 static const uschar *sid_ctx = US"exim";
49 static SSL_CTX *client_ctx = NULL;
50 static SSL_CTX *server_ctx = NULL;
51 static SSL *client_ssl = NULL;
52 static SSL *server_ssl = NULL;
53 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
54 static SSL_CTX *client_sni = NULL;
55 static SSL_CTX *server_sni = NULL;
58 static char ssl_errstring[256];
60 static int ssl_session_timeout = 200;
61 static BOOL client_verify_optional = FALSE;
62 static BOOL server_verify_optional = FALSE;
64 static BOOL reexpand_tls_files_for_sni = FALSE;
67 typedef struct tls_ext_ctx_cb {
70 #ifdef EXPERIMENTAL_OCSP
72 uschar *ocsp_file_expanded;
73 OCSP_RESPONSE *ocsp_response;
76 /* these are cached from first expand */
77 uschar *server_cipher_list;
78 /* only passed down to tls_error: */
82 /* should figure out a cleanup of API to handle state preserved per
83 implementation, for various reasons, which can be void * in the APIs.
84 For now, we hack around it. */
85 tls_ext_ctx_cb *client_static_cbinfo = NULL;
86 tls_ext_ctx_cb *server_static_cbinfo = NULL;
89 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, BOOL client);
92 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
93 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
95 #ifdef EXPERIMENTAL_OCSP
96 static int tls_stapling_cb(SSL *s, void *arg);
100 /*************************************************
102 *************************************************/
104 /* Called from lots of places when errors occur before actually starting to do
105 the TLS handshake, that is, while the session is still in clear. Always returns
106 DEFER for a server and FAIL for a client so that most calls can use "return
107 tls_error(...)" to do this processing and then give an appropriate return. A
108 single function is used for both server and client, because it is called from
109 some shared functions.
112 prefix text to include in the logged error
113 host NULL if setting up a server;
114 the connected host if setting up a client
115 msg error message or NULL if we should ask OpenSSL
117 Returns: OK/DEFER/FAIL
121 tls_error(uschar *prefix, host_item *host, uschar *msg)
125 ERR_error_string(ERR_get_error(), ssl_errstring);
126 msg = (uschar *)ssl_errstring;
131 uschar *conn_info = smtp_get_connection_info();
132 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
134 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
135 conn_info, prefix, msg);
140 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
141 host->name, host->address, prefix, msg);
148 /*************************************************
149 * Callback to generate RSA key *
150 *************************************************/
158 Returns: pointer to generated key
162 rsa_callback(SSL *s, int export, int keylength)
165 export = export; /* Shut picky compilers up */
166 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
167 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
170 ERR_error_string(ERR_get_error(), ssl_errstring);
171 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
181 /*************************************************
182 * Callback for verification *
183 *************************************************/
185 /* The SSL library does certificate verification if set up to do so. This
186 callback has the current yes/no state is in "state". If verification succeeded,
187 we set up the tls_peerdn string. If verification failed, what happens depends
188 on whether the client is required to present a verifiable certificate or not.
190 If verification is optional, we change the state to yes, but still log the
191 verification error. For some reason (it really would help to have proper
192 documentation of OpenSSL), this callback function then gets called again, this
193 time with state = 1. In fact, that's useful, because we can set up the peerdn
194 value, but we must take care not to set the private verified flag on the second
197 Note: this function is not called if the client fails to present a certificate
198 when asked. We get here only if a certificate has been received. Handling of
199 optional verification for this case is done when requesting SSL to verify, by
200 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
203 state current yes/no state as 1/0
204 x509ctx certificate information.
205 client TRUE for client startup, FALSE for server startup
207 Returns: 1 if verified, 0 if not
211 verify_callback(int state, X509_STORE_CTX *x509ctx, BOOL client)
213 static uschar txt[256];
221 calledp= &client_verify_callback_called;
222 optionalp= &client_verify_optional;
227 calledp= &server_verify_callback_called;
228 optionalp= &server_verify_optional;
231 X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert),
232 CS txt, sizeof(txt));
236 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
237 x509ctx->error_depth,
238 X509_verify_cert_error_string(x509ctx->error),
240 tlsp->certificate_verified = FALSE;
242 if (!*optionalp) return 0; /* reject */
243 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
244 "tls_try_verify_hosts)\n");
245 return 1; /* accept */
248 if (x509ctx->error_depth != 0)
250 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n",
251 x509ctx->error_depth, txt);
255 DEBUG(D_tls) debug_printf("SSL%s peer: %s\n",
256 *calledp ? "" : " authenticated", txt);
260 if (!*calledp) tlsp->certificate_verified = TRUE;
263 return 1; /* accept */
267 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
269 return verify_callback(state, x509ctx, TRUE);
273 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
275 return verify_callback(state, x509ctx, FALSE);
280 /*************************************************
281 * Information callback *
282 *************************************************/
284 /* The SSL library functions call this from time to time to indicate what they
285 are doing. We copy the string to the debugging output when TLS debugging has
297 info_callback(SSL *s, int where, int ret)
301 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
306 /*************************************************
307 * Initialize for DH *
308 *************************************************/
310 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
313 dhparam DH parameter file or fixed parameter identity string
314 host connected host, if client; NULL if server
316 Returns: TRUE if OK (nothing to set up, or setup worked)
321 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
323 init_dh(SSL_CTX *ctx, uschar *dhparam, host_item *host)
324 >>>>>>> Dual-tls - split management of TLS into in- and out-bound connection-handling.
331 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
334 if (dhexpanded == NULL || *dhexpanded == '\0')
336 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
338 else if (dhexpanded[0] == '/')
340 bio = BIO_new_file(CS dhexpanded, "r");
343 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
344 host, US strerror(errno));
350 if (Ustrcmp(dhexpanded, "none") == 0)
352 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
356 pem = std_dh_prime_named(dhexpanded);
359 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
360 host, US strerror(errno));
363 bio = BIO_new_mem_buf(CS pem, -1);
366 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
370 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
375 /* Even if it is larger, we silently return success rather than cause things
376 * to fail out, so that a too-large DH will not knock out all TLS; it's a
377 * debatable choice. */
378 if ((8*DH_size(dh)) > tls_dh_max_bits)
381 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
382 8*DH_size(dh), tls_dh_max_bits);
386 SSL_CTX_set_tmp_dh(sctx, dh);
388 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
389 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
401 #ifdef EXPERIMENTAL_OCSP
402 /*************************************************
403 * Load OCSP information into state *
404 *************************************************/
406 /* Called to load the OCSP response from the given file into memory, once
407 caller has determined this is needed. Checks validity. Debugs a message
410 ASSUMES: single response, for single cert.
413 sctx the SSL_CTX* to update
414 cbinfo various parts of session state
415 expanded the filename putatively holding an OCSP response
420 ocsp_load_response(SSL_CTX *sctx,
421 tls_ext_ctx_cb *cbinfo,
422 const uschar *expanded)
426 OCSP_BASICRESP *basic_response;
427 OCSP_SINGLERESP *single_response;
428 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
430 unsigned long verify_flags;
431 int status, reason, i;
433 cbinfo->ocsp_file_expanded = string_copy(expanded);
434 if (cbinfo->ocsp_response)
436 OCSP_RESPONSE_free(cbinfo->ocsp_response);
437 cbinfo->ocsp_response = NULL;
440 bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb");
443 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
444 cbinfo->ocsp_file_expanded);
448 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
452 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
456 status = OCSP_response_status(resp);
457 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
459 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
460 OCSP_response_status_str(status), status);
464 basic_response = OCSP_response_get1_basic(resp);
468 debug_printf("OCSP response parse error: unable to extract basic response.\n");
472 store = SSL_CTX_get_cert_store(sctx);
473 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
475 /* May need to expose ability to adjust those flags?
476 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
477 OCSP_TRUSTOTHER OCSP_NOINTERN */
479 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
483 ERR_error_string(ERR_get_error(), ssl_errstring);
484 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
489 /* Here's the simplifying assumption: there's only one response, for the
490 one certificate we use, and nothing for anything else in a chain. If this
491 proves false, we need to extract a cert id from our issued cert
492 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
493 right cert in the stack and then calls OCSP_single_get0_status()).
495 I'm hoping to avoid reworking a bunch more of how we handle state here. */
496 single_response = OCSP_resp_get0(basic_response, 0);
497 if (!single_response)
500 debug_printf("Unable to get first response from OCSP basic response.\n");
504 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
505 /* how does this status differ from the one above? */
506 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
508 DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n",
509 OCSP_response_status_str(status), status);
513 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
515 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
519 cbinfo->ocsp_response = resp;
526 /*************************************************
527 * Expand key and cert file specs *
528 *************************************************/
530 /* Called once during tls_init and possibly againt during TLS setup, for a
531 new context, if Server Name Indication was used and tls_sni was seen in
532 the certificate string.
535 sctx the SSL_CTX* to update
536 cbinfo various parts of session state
538 Returns: OK/DEFER/FAIL
542 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
546 if (cbinfo->certificate == NULL)
549 if (Ustrstr(cbinfo->certificate, US"tls_sni"))
550 reexpand_tls_files_for_sni = TRUE;
552 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
555 if (expanded != NULL)
557 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
558 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
559 return tls_error(string_sprintf(
560 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
564 if (cbinfo->privatekey != NULL &&
565 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
568 /* If expansion was forced to fail, key_expanded will be NULL. If the result
569 of the expansion is an empty string, ignore it also, and assume the private
570 key is in the same file as the certificate. */
572 if (expanded != NULL && *expanded != 0)
574 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
575 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
576 return tls_error(string_sprintf(
577 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
580 #ifdef EXPERIMENTAL_OCSP
581 if (cbinfo->ocsp_file != NULL)
583 if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded))
586 if (expanded != NULL && *expanded != 0)
588 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
589 if (cbinfo->ocsp_file_expanded &&
590 (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0))
593 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
595 ocsp_load_response(sctx, cbinfo, expanded);
607 /*************************************************
608 * Callback to handle SNI *
609 *************************************************/
611 /* Called when acting as server during the TLS session setup if a Server Name
612 Indication extension was sent by the client.
614 API documentation is OpenSSL s_server.c implementation.
617 s SSL* of the current session
618 ad unknown (part of OpenSSL API) (unused)
619 arg Callback of "our" registered data
621 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
624 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
626 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
628 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
629 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
631 int old_pool = store_pool;
634 return SSL_TLSEXT_ERR_OK;
636 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
637 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
639 /* Make the extension value available for expansion */
640 store_pool = POOL_PERM;
641 tls_in.sni = string_copy(US servername);
642 store_pool = old_pool;
644 if (!reexpand_tls_files_for_sni)
645 return SSL_TLSEXT_ERR_OK;
647 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
648 not confident that memcpy wouldn't break some internal reference counting.
649 Especially since there's a references struct member, which would be off. */
651 server_sni = SSL_CTX_new(SSLv23_server_method());
654 ERR_error_string(ERR_get_error(), ssl_errstring);
655 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
656 return SSL_TLSEXT_ERR_NOACK;
659 /* Not sure how many of these are actually needed, since SSL object
660 already exists. Might even need this selfsame callback, for reneg? */
662 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
663 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
664 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
665 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
666 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
667 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
668 if (cbinfo->server_cipher_list)
669 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
670 #ifdef EXPERIMENTAL_OCSP
671 if (cbinfo->ocsp_file)
673 SSL_CTX_set_tlsext_status_cb(server_sni, tls_stapling_cb);
674 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
678 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, FALSE);
679 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
681 /* do this after setup_certs, because this can require the certs for verifying
683 rc = tls_expand_session_files(server_sni, cbinfo);
684 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
686 rc = init_dh(ctx_sni, cbinfo->dhparam, NULL);
687 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
689 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
690 SSL_set_SSL_CTX(s, server_sni);
692 return SSL_TLSEXT_ERR_OK;
694 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
699 #ifdef EXPERIMENTAL_OCSP
700 /*************************************************
701 * Callback to handle OCSP Stapling *
702 *************************************************/
704 /* Called when acting as server during the TLS session setup if the client
705 requests OCSP information with a Certificate Status Request.
707 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
713 tls_stapling_cb(SSL *s, void *arg)
715 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
716 uschar *response_der;
717 int response_der_len;
719 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n",
720 cbinfo->ocsp_response ? "have" : "lack");
721 if (!cbinfo->ocsp_response)
722 return SSL_TLSEXT_ERR_NOACK;
725 response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der);
726 if (response_der_len <= 0)
727 return SSL_TLSEXT_ERR_NOACK;
729 SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len);
730 return SSL_TLSEXT_ERR_OK;
733 #endif /* EXPERIMENTAL_OCSP */
738 /*************************************************
739 * Initialize for TLS *
740 *************************************************/
742 /* Called from both server and client code, to do preliminary initialization of
746 host connected host, if client; NULL if server
747 dhparam DH parameter file
748 certificate certificate file
749 privatekey private key
750 addr address if client; NULL if server (for some randomness)
752 Returns: OK/DEFER/FAIL
756 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
758 #ifdef EXPERIMENTAL_OCSP
761 address_item *addr, tls_ext_ctx_cb ** cbp)
766 tls_ext_ctx_cb *cbinfo;
768 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
769 cbinfo->certificate = certificate;
770 cbinfo->privatekey = privatekey;
771 #ifdef EXPERIMENTAL_OCSP
772 cbinfo->ocsp_file = ocsp_file;
774 cbinfo->dhparam = dhparam;
777 SSL_load_error_strings(); /* basic set up */
778 OpenSSL_add_ssl_algorithms();
780 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
781 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
782 list of available digests. */
783 EVP_add_digest(EVP_sha256());
787 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
788 negotiation in the different methods; as far as I can tell, the only
789 *_{server,client}_method which allows negotiation is SSLv23, which exists even
790 when OpenSSL is built without SSLv2 support.
791 By disabling with openssl_options, we can let admins re-enable with the
794 *ctxp = SSL_CTX_new((host == NULL)?
795 SSLv23_server_method() : SSLv23_client_method());
797 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
799 /* It turns out that we need to seed the random number generator this early in
800 order to get the full complement of ciphers to work. It took me roughly a day
801 of work to discover this by experiment.
803 On systems that have /dev/urandom, SSL may automatically seed itself from
804 there. Otherwise, we have to make something up as best we can. Double check
810 gettimeofday(&r.tv, NULL);
813 RAND_seed((uschar *)(&r), sizeof(r));
814 RAND_seed((uschar *)big_buffer, big_buffer_size);
815 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
818 return tls_error(US"RAND_status", host,
819 US"unable to seed random number generator");
822 /* Set up the information callback, which outputs if debugging is at a suitable
825 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
827 /* Automatically re-try reads/writes after renegotiation. */
828 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
830 /* Apply administrator-supplied work-arounds.
831 Historically we applied just one requested option,
832 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
833 moved to an administrator-controlled list of options to specify and
834 grandfathered in the first one as the default value for "openssl_options".
836 No OpenSSL version number checks: the options we accept depend upon the
837 availability of the option value macros from OpenSSL. */
839 okay = tls_openssl_options_parse(openssl_options, &init_options);
841 return tls_error(US"openssl_options parsing failed", host, NULL);
845 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
846 if (!(SSL_CTX_set_options(*ctxp, init_options)))
847 return tls_error(string_sprintf(
848 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
851 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
853 /* Initialize with DH parameters if supplied */
856 if (!init_dh(ctx, dhparam, host)) return DEFER;
858 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
859 >>>>>>> Dual-tls - split management of TLS into in- and out-bound connection-handling.
861 /* Set up certificate and key (and perhaps OCSP info) */
863 rc = tls_expand_session_files(*ctxp, cbinfo);
864 if (rc != OK) return rc;
866 /* If we need to handle SNI, do so */
867 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
870 #ifdef EXPERIMENTAL_OCSP
871 /* We check ocsp_file, not ocsp_response, because we care about if
872 the option exists, not what the current expansion might be, as SNI might
873 change the certificate and OCSP file in use between now and the time the
874 callback is invoked. */
875 if (cbinfo->ocsp_file)
877 SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb);
878 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
881 /* We always do this, so that $tls_sni is available even if not used in
883 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
884 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
888 /* Set up the RSA callback */
890 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
892 /* Finally, set the timeout, and we are done */
894 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
895 DEBUG(D_tls) debug_printf("Initialized TLS\n");
905 /*************************************************
906 * Get name of cipher in use *
907 *************************************************/
910 Argument: pointer to an SSL structure for the connection
911 buffer to use for answer
913 pointer to number of bits for cipher
918 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
920 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
921 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
922 the accessor functions use const in the prototype. */
926 switch (ssl->session->ssl_version)
940 #ifdef TLS1_1_VERSION
946 #ifdef TLS1_2_VERSION
956 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
957 SSL_CIPHER_get_bits(c, bits);
959 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
960 SSL_CIPHER_get_name(c), *bits);
962 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
969 /*************************************************
970 * Set up for verifying certificates *
971 *************************************************/
973 /* Called by both client and server startup
976 sctx SSL_CTX* to initialise
977 certs certs file or NULL
979 host NULL in a server; the remote host in a client
980 optional TRUE if called from a server for a host in tls_try_verify_hosts;
981 otherwise passed as FALSE
982 client TRUE if called for client startup, FALSE for server startup
984 Returns: OK/DEFER/FAIL
988 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, BOOL client)
990 uschar *expcerts, *expcrl;
992 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
995 if (expcerts != NULL)
998 if (!SSL_CTX_set_default_verify_paths(sctx))
999 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1001 if (Ustat(expcerts, &statbuf) < 0)
1003 log_write(0, LOG_MAIN|LOG_PANIC,
1004 "failed to stat %s for certificates", expcerts);
1010 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1011 { file = NULL; dir = expcerts; }
1013 { file = expcerts; dir = NULL; }
1015 /* If a certificate file is empty, the next function fails with an
1016 unhelpful error message. If we skip it, we get the correct behaviour (no
1017 certificates are recognized, but the error message is still misleading (it
1018 says no certificate was supplied.) But this is better. */
1020 if ((file == NULL || statbuf.st_size > 0) &&
1021 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1022 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1026 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
1030 /* Handle a certificate revocation list. */
1032 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1034 /* This bit of code is now the version supplied by Lars Mainka. (I have
1035 * merely reformatted it into the Exim code style.)
1037 * "From here I changed the code to add support for multiple crl's
1038 * in pem format in one file or to support hashed directory entries in
1039 * pem format instead of a file. This method now uses the library function
1040 * X509_STORE_load_locations to add the CRL location to the SSL context.
1041 * OpenSSL will then handle the verify against CA certs and CRLs by
1042 * itself in the verify callback." */
1044 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1045 if (expcrl != NULL && *expcrl != 0)
1047 struct stat statbufcrl;
1048 if (Ustat(expcrl, &statbufcrl) < 0)
1050 log_write(0, LOG_MAIN|LOG_PANIC,
1051 "failed to stat %s for certificates revocation lists", expcrl);
1056 /* is it a file or directory? */
1058 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1059 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1063 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1069 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1071 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1072 return tls_error(US"X509_STORE_load_locations", host, NULL);
1074 /* setting the flags to check against the complete crl chain */
1076 X509_STORE_set_flags(cvstore,
1077 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1081 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1083 /* If verification is optional, don't fail if no certificate */
1085 SSL_CTX_set_verify(sctx,
1086 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1087 client ? verify_callback_client : verify_callback_server);
1095 /*************************************************
1096 * Start a TLS session in a server *
1097 *************************************************/
1099 /* This is called when Exim is running as a server, after having received
1100 the STARTTLS command. It must respond to that command, and then negotiate
1104 require_ciphers allowed ciphers
1106 Returns: OK on success
1107 DEFER for errors before the start of the negotiation
1108 FAIL for errors during the negotation; the server can't
1113 tls_server_start(const uschar *require_ciphers)
1117 tls_ext_ctx_cb *cbinfo;
1118 static uschar cipherbuf[256];
1120 /* Check for previous activation */
1122 if (tls_in.active >= 0)
1124 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1125 smtp_printf("554 Already in TLS\r\n");
1129 /* Initialize the SSL library. If it fails, it will already have logged
1132 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1133 #ifdef EXPERIMENTAL_OCSP
1136 NULL, &server_static_cbinfo);
1137 if (rc != OK) return rc;
1138 cbinfo = server_static_cbinfo;
1140 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1143 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1144 were historically separated by underscores. So that I can use either form in my
1145 tests, and also for general convenience, we turn underscores into hyphens here.
1148 if (expciphers != NULL)
1150 uschar *s = expciphers;
1151 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1152 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1153 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1154 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1155 cbinfo->server_cipher_list = expciphers;
1158 /* If this is a host for which certificate verification is mandatory or
1159 optional, set up appropriately. */
1161 tls_in.certificate_verified = FALSE;
1162 server_verify_callback_called = FALSE;
1164 if (verify_check_host(&tls_verify_hosts) == OK)
1166 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, FALSE, FALSE);
1167 if (rc != OK) return rc;
1168 server_verify_optional = FALSE;
1170 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1172 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, TRUE, FALSE);
1173 if (rc != OK) return rc;
1174 server_verify_optional = TRUE;
1177 /* Prepare for new connection */
1179 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1181 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1183 * With the SSL_clear(), we get strange interoperability bugs with
1184 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1185 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1187 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1188 * session shutdown. In this case, we have a brand new object and there's no
1189 * obvious reason to immediately clear it. I'm guessing that this was
1190 * originally added because of incomplete initialisation which the clear fixed,
1191 * in some historic release.
1194 /* Set context and tell client to go ahead, except in the case of TLS startup
1195 on connection, where outputting anything now upsets the clients and tends to
1196 make them disconnect. We need to have an explicit fflush() here, to force out
1197 the response. Other smtp_printf() calls do not need it, because in non-TLS
1198 mode, the fflush() happens when smtp_getc() is called. */
1200 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1201 if (!tls_in.on_connect)
1203 smtp_printf("220 TLS go ahead\r\n");
1207 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1208 that the OpenSSL library doesn't. */
1210 SSL_set_wfd(server_ssl, fileno(smtp_out));
1211 SSL_set_rfd(server_ssl, fileno(smtp_in));
1212 SSL_set_accept_state(server_ssl);
1214 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1216 sigalrm_seen = FALSE;
1217 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1218 rc = SSL_accept(server_ssl);
1223 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1224 if (ERR_get_error() == 0)
1225 log_write(0, LOG_MAIN,
1226 "TLS client disconnected cleanly (rejected our certificate?)");
1230 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1232 /* TLS has been set up. Adjust the input functions to read via TLS,
1233 and initialize things. */
1235 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1236 tls_in.cipher = cipherbuf;
1241 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1242 debug_printf("Shared ciphers: %s\n", buf);
1246 /* Only used by the server-side tls (tls_in), including tls_getc.
1247 Client-side (tls_out) reads (seem to?) go via
1248 smtp_read_response()/ip_recv().
1249 Hence no need to duplicate for _in and _out.
1251 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1252 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1253 ssl_xfer_eof = ssl_xfer_error = 0;
1255 receive_getc = tls_getc;
1256 receive_ungetc = tls_ungetc;
1257 receive_feof = tls_feof;
1258 receive_ferror = tls_ferror;
1259 receive_smtp_buffered = tls_smtp_buffered;
1261 tls_in.active = fileno(smtp_out);
1269 /*************************************************
1270 * Start a TLS session in a client *
1271 *************************************************/
1273 /* Called from the smtp transport after STARTTLS has been accepted.
1276 fd the fd of the connection
1277 host connected host (for messages)
1278 addr the first address
1279 dhparam DH parameter file
1280 certificate certificate file
1281 privatekey private key file
1282 sni TLS SNI to send to remote host
1283 verify_certs file for certificate verify
1284 crl file containing CRL
1285 require_ciphers list of allowed ciphers
1286 dh_min_bits minimum number of bits acceptable in server's DH prime
1288 timeout startup timeout
1290 Returns: OK on success
1291 FAIL otherwise - note that tls_error() will not give DEFER
1292 because this is not a server
1296 tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
1297 uschar *certificate, uschar *privatekey, uschar *sni,
1298 uschar *verify_certs, uschar *crl,
1299 uschar *require_ciphers, int dh_min_bits ARG_UNUSED, int timeout)
1301 static uschar txt[256];
1305 static uschar cipherbuf[256];
1307 rc = tls_init(&client_ctx, host, dhparam, certificate, privatekey,
1308 #ifdef EXPERIMENTAL_OCSP
1311 addr, &client_static_cbinfo);
1312 if (rc != OK) return rc;
1314 tls_out.certificate_verified = FALSE;
1315 client_verify_callback_called = FALSE;
1317 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1320 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1321 are separated by underscores. So that I can use either form in my tests, and
1322 also for general convenience, we turn underscores into hyphens here. */
1324 if (expciphers != NULL)
1326 uschar *s = expciphers;
1327 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1328 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1329 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1330 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1333 rc = setup_certs(client_ctx, verify_certs, crl, host, FALSE, TRUE);
1334 if (rc != OK) return rc;
1336 if ((client_ssl = SSL_new(client_ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1337 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1338 SSL_set_fd(client_ssl, fd);
1339 SSL_set_connect_state(client_ssl);
1343 if (!expand_check(sni, US"tls_sni", &tls_out.sni))
1345 if (!Ustrlen(tls_out.sni))
1349 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1350 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1351 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1354 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1360 /* There doesn't seem to be a built-in timeout on connection. */
1362 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1363 sigalrm_seen = FALSE;
1365 rc = SSL_connect(client_ssl);
1369 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1371 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1373 /* Beware anonymous ciphers which lead to server_cert being NULL */
1374 server_cert = SSL_get_peer_certificate (client_ssl);
1377 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1378 CS txt, sizeof(txt));
1379 tls_out.peerdn = txt;
1382 tls_out.peerdn = NULL;
1384 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1385 tls_out.cipher = cipherbuf;
1387 tls_out.active = fd;
1395 /*************************************************
1396 * TLS version of getc *
1397 *************************************************/
1399 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1400 it refills the buffer via the SSL reading function.
1403 Returns: the next character or EOF
1405 Only used by the server-side TLS.
1411 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1416 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
1417 ssl_xfer_buffer, ssl_xfer_buffer_size);
1419 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1420 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1421 error = SSL_get_error(server_ssl, inbytes);
1424 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1425 closed down, not that the socket itself has been closed down. Revert to
1426 non-SSL handling. */
1428 if (error == SSL_ERROR_ZERO_RETURN)
1430 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1432 receive_getc = smtp_getc;
1433 receive_ungetc = smtp_ungetc;
1434 receive_feof = smtp_feof;
1435 receive_ferror = smtp_ferror;
1436 receive_smtp_buffered = smtp_buffered;
1438 SSL_free(server_ssl);
1442 tls_in.cipher = NULL;
1443 tls_in.peerdn = NULL;
1449 /* Handle genuine errors */
1451 else if (error == SSL_ERROR_SSL)
1453 ERR_error_string(ERR_get_error(), ssl_errstring);
1454 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
1459 else if (error != SSL_ERROR_NONE)
1461 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1466 #ifndef DISABLE_DKIM
1467 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1469 ssl_xfer_buffer_hwm = inbytes;
1470 ssl_xfer_buffer_lwm = 0;
1473 /* Something in the buffer; return next uschar */
1475 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1480 /*************************************************
1481 * Read bytes from TLS channel *
1482 *************************************************/
1489 Returns: the number of bytes read
1490 -1 after a failed read
1492 Only used by the client-side TLS.
1496 tls_read(uschar *buff, size_t len)
1501 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", client_ssl,
1502 buff, (unsigned int)len);
1504 inbytes = SSL_read(client_ssl, CS buff, len);
1505 error = SSL_get_error(client_ssl, inbytes);
1507 if (error == SSL_ERROR_ZERO_RETURN)
1509 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1512 else if (error != SSL_ERROR_NONE)
1524 /*************************************************
1525 * Write bytes down TLS channel *
1526 *************************************************/
1530 is_server channel specifier
1534 Returns: the number of bytes after a successful write,
1535 -1 after a failed write
1537 Used by both server-side and client-side TLS.
1541 tls_write(BOOL is_server, const uschar *buff, size_t len)
1546 SSL *ssl = is_server ? server_ssl : client_ssl;
1548 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
1551 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
1552 outbytes = SSL_write(ssl, CS buff, left);
1553 error = SSL_get_error(ssl, outbytes);
1554 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1558 ERR_error_string(ERR_get_error(), ssl_errstring);
1559 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1562 case SSL_ERROR_NONE:
1567 case SSL_ERROR_ZERO_RETURN:
1568 log_write(0, LOG_MAIN, "SSL channel closed on write");
1571 case SSL_ERROR_SYSCALL:
1572 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
1573 sender_fullhost ? sender_fullhost : US"<unknown>",
1577 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1586 /*************************************************
1587 * Close down a TLS session *
1588 *************************************************/
1590 /* This is also called from within a delivery subprocess forked from the
1591 daemon, to shut down the TLS library, without actually doing a shutdown (which
1592 would tamper with the SSL session in the parent process).
1594 Arguments: TRUE if SSL_shutdown is to be called
1597 Used by both server-side and client-side TLS.
1601 tls_close(BOOL is_server, BOOL shutdown)
1603 SSL **sslp = is_server ? &server_ssl : &client_ssl;
1605 if (*fdp < 0) return; /* TLS was not active */
1609 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
1610 SSL_shutdown(*sslp);
1622 /*************************************************
1623 * Let tls_require_ciphers be checked at startup *
1624 *************************************************/
1626 /* The tls_require_ciphers option, if set, must be something which the
1629 Returns: NULL on success, or error message
1633 tls_validate_require_cipher(void)
1636 uschar *s, *expciphers, *err;
1638 /* this duplicates from tls_init(), we need a better "init just global
1639 state, for no specific purpose" singleton function of our own */
1641 SSL_load_error_strings();
1642 OpenSSL_add_ssl_algorithms();
1643 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1644 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1645 list of available digests. */
1646 EVP_add_digest(EVP_sha256());
1649 if (!(tls_require_ciphers && *tls_require_ciphers))
1652 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1653 return US"failed to expand tls_require_ciphers";
1655 if (!(expciphers && *expciphers))
1658 /* normalisation ripped from above */
1660 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1664 ctx = SSL_CTX_new(SSLv23_server_method());
1667 ERR_error_string(ERR_get_error(), ssl_errstring);
1668 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1672 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1674 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1676 ERR_error_string(ERR_get_error(), ssl_errstring);
1677 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1688 /*************************************************
1689 * Report the library versions. *
1690 *************************************************/
1692 /* There have historically been some issues with binary compatibility in
1693 OpenSSL libraries; if Exim (like many other applications) is built against
1694 one version of OpenSSL but the run-time linker picks up another version,
1695 it can result in serious failures, including crashing with a SIGSEGV. So
1696 report the version found by the compiler and the run-time version.
1698 Arguments: a FILE* to print the results to
1703 tls_version_report(FILE *f)
1705 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1707 OPENSSL_VERSION_TEXT,
1708 SSLeay_version(SSLEAY_VERSION));
1714 /*************************************************
1715 * Random number generation *
1716 *************************************************/
1718 /* Pseudo-random number generation. The result is not expected to be
1719 cryptographically strong but not so weak that someone will shoot themselves
1720 in the foot using it as a nonce in input in some email header scheme or
1721 whatever weirdness they'll twist this into. The result should handle fork()
1722 and avoid repeating sequences. OpenSSL handles that for us.
1726 Returns a random number in range [0, max-1]
1730 vaguely_random_number(int max)
1735 uschar smallbuf[sizeof(r)];
1740 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1744 gettimeofday(&r.tv, NULL);
1747 RAND_seed((uschar *)(&r), sizeof(r));
1749 /* We're after pseudo-random, not random; if we still don't have enough data
1750 in the internal PRNG then our options are limited. We could sleep and hope
1751 for entropy to come along (prayer technique) but if the system is so depleted
1752 in the first place then something is likely to just keep taking it. Instead,
1753 we'll just take whatever little bit of pseudo-random we can still manage to
1756 needed_len = sizeof(r);
1757 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1758 asked for a number less than 10. */
1759 for (r = max, i = 0; r; ++i)
1765 /* We do not care if crypto-strong */
1766 i = RAND_pseudo_bytes(smallbuf, needed_len);
1770 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
1771 return vaguely_random_number_fallback(max);
1775 for (p = smallbuf; needed_len; --needed_len, ++p)
1781 /* We don't particularly care about weighted results; if someone wants
1782 smooth distribution and cares enough then they should submit a patch then. */
1789 /*************************************************
1790 * OpenSSL option parse *
1791 *************************************************/
1793 /* Parse one option for tls_openssl_options_parse below
1796 name one option name
1797 value place to store a value for it
1798 Returns success or failure in parsing
1801 struct exim_openssl_option {
1805 /* We could use a macro to expand, but we need the ifdef and not all the
1806 options document which version they were introduced in. Policylet: include
1807 all options unless explicitly for DTLS, let the administrator choose which
1810 This list is current as of:
1812 static struct exim_openssl_option exim_openssl_options[] = {
1813 /* KEEP SORTED ALPHABETICALLY! */
1815 { US"all", SSL_OP_ALL },
1817 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1818 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
1820 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1821 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
1823 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1824 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
1826 #ifdef SSL_OP_EPHEMERAL_RSA
1827 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
1829 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1830 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
1832 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1833 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
1835 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1836 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
1838 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1839 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
1841 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1842 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
1844 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1845 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
1847 #ifdef SSL_OP_NO_COMPRESSION
1848 { US"no_compression", SSL_OP_NO_COMPRESSION },
1850 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1851 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
1853 #ifdef SSL_OP_NO_SSLv2
1854 { US"no_sslv2", SSL_OP_NO_SSLv2 },
1856 #ifdef SSL_OP_NO_SSLv3
1857 { US"no_sslv3", SSL_OP_NO_SSLv3 },
1859 #ifdef SSL_OP_NO_TICKET
1860 { US"no_ticket", SSL_OP_NO_TICKET },
1862 #ifdef SSL_OP_NO_TLSv1
1863 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
1865 #ifdef SSL_OP_NO_TLSv1_1
1866 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1867 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1868 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1870 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
1873 #ifdef SSL_OP_NO_TLSv1_2
1874 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
1876 #ifdef SSL_OP_SINGLE_DH_USE
1877 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
1879 #ifdef SSL_OP_SINGLE_ECDH_USE
1880 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
1882 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1883 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
1885 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1886 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
1888 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1889 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
1891 #ifdef SSL_OP_TLS_D5_BUG
1892 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
1894 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1895 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
1898 static int exim_openssl_options_size =
1899 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
1903 tls_openssl_one_option_parse(uschar *name, long *value)
1906 int last = exim_openssl_options_size;
1907 while (last > first)
1909 int middle = (first + last)/2;
1910 int c = Ustrcmp(name, exim_openssl_options[middle].name);
1913 *value = exim_openssl_options[middle].value;
1927 /*************************************************
1928 * OpenSSL option parsing logic *
1929 *************************************************/
1931 /* OpenSSL has a number of compatibility options which an administrator might
1932 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
1933 we look like log_selector.
1936 option_spec the administrator-supplied string of options
1937 results ptr to long storage for the options bitmap
1938 Returns success or failure
1942 tls_openssl_options_parse(uschar *option_spec, long *results)
1947 BOOL adding, item_parsed;
1950 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
1951 * from default because it increases BEAST susceptibility. */
1952 #ifdef SSL_OP_NO_SSLv2
1953 result |= SSL_OP_NO_SSLv2;
1956 if (option_spec == NULL)
1962 for (s=option_spec; *s != '\0'; /**/)
1964 while (isspace(*s)) ++s;
1967 if (*s != '+' && *s != '-')
1969 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
1970 "+ or - expected but found \"%s\"\n", s);
1973 adding = *s++ == '+';
1974 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
1977 item_parsed = tls_openssl_one_option_parse(s, &item);
1980 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
1983 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1984 adding ? "adding" : "removing", result, item, s);
1997 /* End of tls-openssl.c */