1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2014 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Portions Copyright (c) The OpenSSL Project 1999 */
10 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11 library. It is #included into the tls.c file when that library is used. The
12 code herein is based on a patch that was originally contributed by Steve
13 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
15 No cryptographic code is included in Exim. All this module does is to call
16 functions from the OpenSSL library. */
21 #include <openssl/lhash.h>
22 #include <openssl/ssl.h>
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
26 # include <openssl/ocsp.h>
30 # define EXIM_OCSP_SKEW_SECONDS (300L)
31 # define EXIM_OCSP_MAX_AGE (-1L)
34 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
35 # define EXIM_HAVE_OPENSSL_TLSEXT
38 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
39 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
43 /* Structure for collecting random data for seeding. */
45 typedef struct randstuff {
50 /* Local static variables */
52 static BOOL client_verify_callback_called = FALSE;
53 static BOOL server_verify_callback_called = FALSE;
54 static const uschar *sid_ctx = US"exim";
56 /* We have three different contexts to care about.
58 Simple case: client, `client_ctx`
59 As a client, we can be doing a callout or cut-through delivery while receiving
60 a message. So we have a client context, which should have options initialised
61 from the SMTP Transport.
64 There are two cases: with and without ServerNameIndication from the client.
65 Given TLS SNI, we can be using different keys, certs and various other
66 configuration settings, because they're re-expanded with $tls_sni set. This
67 allows vhosting with TLS. This SNI is sent in the handshake.
68 A client might not send SNI, so we need a fallback, and an initial setup too.
69 So as a server, we start out using `server_ctx`.
70 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
71 `server_sni` from `server_ctx` and then initialise settings by re-expanding
75 static SSL_CTX *client_ctx = NULL;
76 static SSL_CTX *server_ctx = NULL;
77 static SSL *client_ssl = NULL;
78 static SSL *server_ssl = NULL;
80 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
81 static SSL_CTX *server_sni = NULL;
84 static char ssl_errstring[256];
86 static int ssl_session_timeout = 200;
87 static BOOL client_verify_optional = FALSE;
88 static BOOL server_verify_optional = FALSE;
90 static BOOL reexpand_tls_files_for_sni = FALSE;
93 typedef struct tls_ext_ctx_cb {
101 uschar *file_expanded;
102 OCSP_RESPONSE *response;
105 X509_STORE *verify_store; /* non-null if status requested */
106 BOOL verify_required;
111 /* these are cached from first expand */
112 uschar *server_cipher_list;
113 /* only passed down to tls_error: */
116 #ifdef EXPERIMENTAL_CERTNAMES
117 uschar * verify_cert_hostnames;
121 /* should figure out a cleanup of API to handle state preserved per
122 implementation, for various reasons, which can be void * in the APIs.
123 For now, we hack around it. */
124 tls_ext_ctx_cb *client_static_cbinfo = NULL;
125 tls_ext_ctx_cb *server_static_cbinfo = NULL;
128 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
129 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
132 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
133 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
136 static int tls_server_stapling_cb(SSL *s, void *arg);
140 /*************************************************
142 *************************************************/
144 /* Called from lots of places when errors occur before actually starting to do
145 the TLS handshake, that is, while the session is still in clear. Always returns
146 DEFER for a server and FAIL for a client so that most calls can use "return
147 tls_error(...)" to do this processing and then give an appropriate return. A
148 single function is used for both server and client, because it is called from
149 some shared functions.
152 prefix text to include in the logged error
153 host NULL if setting up a server;
154 the connected host if setting up a client
155 msg error message or NULL if we should ask OpenSSL
157 Returns: OK/DEFER/FAIL
161 tls_error(uschar *prefix, host_item *host, uschar *msg)
165 ERR_error_string(ERR_get_error(), ssl_errstring);
166 msg = (uschar *)ssl_errstring;
171 uschar *conn_info = smtp_get_connection_info();
172 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
174 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
175 conn_info, prefix, msg);
180 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
181 host->name, host->address, prefix, msg);
188 /*************************************************
189 * Callback to generate RSA key *
190 *************************************************/
198 Returns: pointer to generated key
202 rsa_callback(SSL *s, int export, int keylength)
205 export = export; /* Shut picky compilers up */
206 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
207 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
210 ERR_error_string(ERR_get_error(), ssl_errstring);
211 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
223 x509_store_dump_cert_s_names(X509_STORE * store)
225 STACK_OF(X509_OBJECT) * roots= store->objs;
227 static uschar name[256];
229 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
231 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
232 if(tmp_obj->type == X509_LU_X509)
234 X509 * current_cert= tmp_obj->data.x509;
235 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
236 debug_printf(" %s\n", name);
244 /*************************************************
245 * Callback for verification *
246 *************************************************/
248 /* The SSL library does certificate verification if set up to do so. This
249 callback has the current yes/no state is in "state". If verification succeeded,
250 we set up the tls_peerdn string. If verification failed, what happens depends
251 on whether the client is required to present a verifiable certificate or not.
253 If verification is optional, we change the state to yes, but still log the
254 verification error. For some reason (it really would help to have proper
255 documentation of OpenSSL), this callback function then gets called again, this
256 time with state = 1. In fact, that's useful, because we can set up the peerdn
257 value, but we must take care not to set the private verified flag on the second
260 Note: this function is not called if the client fails to present a certificate
261 when asked. We get here only if a certificate has been received. Handling of
262 optional verification for this case is done when requesting SSL to verify, by
263 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
266 state current yes/no state as 1/0
267 x509ctx certificate information.
268 client TRUE for client startup, FALSE for server startup
270 Returns: 1 if verified, 0 if not
274 verify_callback(int state, X509_STORE_CTX *x509ctx,
275 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
277 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
278 static uschar txt[256];
280 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
284 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
285 X509_STORE_CTX_get_error_depth(x509ctx),
286 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
288 tlsp->certificate_verified = FALSE;
292 tlsp->peercert = X509_dup(cert);
293 return 0; /* reject */
295 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
296 "tls_try_verify_hosts)\n");
299 else if (X509_STORE_CTX_get_error_depth(x509ctx) != 0)
301 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n",
302 X509_STORE_CTX_get_error_depth(x509ctx), txt);
304 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
305 { /* client, wanting stapling */
306 /* Add the server cert's signing chain as the one
307 for the verification of the OCSP stapled information. */
309 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
317 #ifdef EXPERIMENTAL_CERTNAMES
318 uschar * verify_cert_hostnames;
322 tlsp->peercert = X509_dup(cert);
324 #ifdef EXPERIMENTAL_CERTNAMES
325 if ( tlsp == &tls_out
326 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
327 /* client, wanting hostname check */
329 # if OPENSSL_VERSION_NUMBER >= 0x010100000L || OPENSSL_VERSION_NUMBER >= 0x010002000L
330 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
331 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
335 uschar * list = verify_cert_hostnames;
338 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
339 if ((rc = X509_check_host(cert, name, 0,
340 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)))
344 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
351 log_write(0, LOG_MAIN,
352 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
353 return 0; /* reject */
357 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
359 log_write(0, LOG_MAIN,
360 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
361 return 0; /* reject */
364 #endif /*EXPERIMENTAL_CERTNAMES*/
366 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
367 *calledp ? "" : " authenticated", txt);
368 if (!*calledp) tlsp->certificate_verified = TRUE;
372 return 1; /* accept */
376 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
378 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
382 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
384 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
388 #ifdef EXPERIMENTAL_DANE
389 /* This gets called *by* the dane library verify callback, which interposes
393 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
395 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
396 static uschar txt[256];
398 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
400 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
401 tls_out.peerdn = txt;
402 tls_out.peercert = X509_dup(cert);
405 tls_out.certificate_verified = TRUE;
411 /*************************************************
412 * Information callback *
413 *************************************************/
415 /* The SSL library functions call this from time to time to indicate what they
416 are doing. We copy the string to the debugging output when TLS debugging has
428 info_callback(SSL *s, int where, int ret)
432 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
437 /*************************************************
438 * Initialize for DH *
439 *************************************************/
441 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
444 dhparam DH parameter file or fixed parameter identity string
445 host connected host, if client; NULL if server
447 Returns: TRUE if OK (nothing to set up, or setup worked)
451 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
458 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
461 if (!dhexpanded || !*dhexpanded)
462 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
463 else if (dhexpanded[0] == '/')
465 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
467 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
468 host, US strerror(errno));
474 if (Ustrcmp(dhexpanded, "none") == 0)
476 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
480 if (!(pem = std_dh_prime_named(dhexpanded)))
482 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
483 host, US strerror(errno));
486 bio = BIO_new_mem_buf(CS pem, -1);
489 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
492 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
497 /* Even if it is larger, we silently return success rather than cause things
498 * to fail out, so that a too-large DH will not knock out all TLS; it's a
499 * debatable choice. */
500 if ((8*DH_size(dh)) > tls_dh_max_bits)
503 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
504 8*DH_size(dh), tls_dh_max_bits);
508 SSL_CTX_set_tmp_dh(sctx, dh);
510 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
511 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
524 /*************************************************
525 * Load OCSP information into state *
526 *************************************************/
528 /* Called to load the server OCSP response from the given file into memory, once
529 caller has determined this is needed. Checks validity. Debugs a message
532 ASSUMES: single response, for single cert.
535 sctx the SSL_CTX* to update
536 cbinfo various parts of session state
537 expanded the filename putatively holding an OCSP response
542 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
546 OCSP_BASICRESP *basic_response;
547 OCSP_SINGLERESP *single_response;
548 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
550 unsigned long verify_flags;
551 int status, reason, i;
553 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
554 if (cbinfo->u_ocsp.server.response)
556 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
557 cbinfo->u_ocsp.server.response = NULL;
560 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
563 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
564 cbinfo->u_ocsp.server.file_expanded);
568 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
572 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
576 status = OCSP_response_status(resp);
577 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
579 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
580 OCSP_response_status_str(status), status);
584 basic_response = OCSP_response_get1_basic(resp);
588 debug_printf("OCSP response parse error: unable to extract basic response.\n");
592 store = SSL_CTX_get_cert_store(sctx);
593 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
595 /* May need to expose ability to adjust those flags?
596 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
597 OCSP_TRUSTOTHER OCSP_NOINTERN */
599 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
603 ERR_error_string(ERR_get_error(), ssl_errstring);
604 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
609 /* Here's the simplifying assumption: there's only one response, for the
610 one certificate we use, and nothing for anything else in a chain. If this
611 proves false, we need to extract a cert id from our issued cert
612 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
613 right cert in the stack and then calls OCSP_single_get0_status()).
615 I'm hoping to avoid reworking a bunch more of how we handle state here. */
616 single_response = OCSP_resp_get0(basic_response, 0);
617 if (!single_response)
620 debug_printf("Unable to get first response from OCSP basic response.\n");
624 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
625 if (status != V_OCSP_CERTSTATUS_GOOD)
627 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
628 OCSP_cert_status_str(status), status,
629 OCSP_crl_reason_str(reason), reason);
633 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
635 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
640 cbinfo->u_ocsp.server.response = resp;
644 if (running_in_test_harness)
646 extern char ** environ;
648 for (p = USS environ; *p != NULL; p++)
649 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
651 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
652 goto supply_response;
657 #endif /*!DISABLE_OCSP*/
662 /*************************************************
663 * Expand key and cert file specs *
664 *************************************************/
666 /* Called once during tls_init and possibly again during TLS setup, for a
667 new context, if Server Name Indication was used and tls_sni was seen in
668 the certificate string.
671 sctx the SSL_CTX* to update
672 cbinfo various parts of session state
674 Returns: OK/DEFER/FAIL
678 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
682 if (cbinfo->certificate == NULL)
685 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
686 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
687 Ustrstr(cbinfo->certificate, US"tls_out_sni")
689 reexpand_tls_files_for_sni = TRUE;
691 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
694 if (expanded != NULL)
696 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
697 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
698 return tls_error(string_sprintf(
699 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
703 if (cbinfo->privatekey != NULL &&
704 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
707 /* If expansion was forced to fail, key_expanded will be NULL. If the result
708 of the expansion is an empty string, ignore it also, and assume the private
709 key is in the same file as the certificate. */
711 if (expanded != NULL && *expanded != 0)
713 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
714 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
715 return tls_error(string_sprintf(
716 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
720 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
722 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
725 if (expanded != NULL && *expanded != 0)
727 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
728 if (cbinfo->u_ocsp.server.file_expanded &&
729 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
732 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
734 ocsp_load_response(sctx, cbinfo, expanded);
746 /*************************************************
747 * Callback to handle SNI *
748 *************************************************/
750 /* Called when acting as server during the TLS session setup if a Server Name
751 Indication extension was sent by the client.
753 API documentation is OpenSSL s_server.c implementation.
756 s SSL* of the current session
757 ad unknown (part of OpenSSL API) (unused)
758 arg Callback of "our" registered data
760 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
763 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
765 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
767 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
768 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
770 int old_pool = store_pool;
773 return SSL_TLSEXT_ERR_OK;
775 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
776 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
778 /* Make the extension value available for expansion */
779 store_pool = POOL_PERM;
780 tls_in.sni = string_copy(US servername);
781 store_pool = old_pool;
783 if (!reexpand_tls_files_for_sni)
784 return SSL_TLSEXT_ERR_OK;
786 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
787 not confident that memcpy wouldn't break some internal reference counting.
788 Especially since there's a references struct member, which would be off. */
790 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
792 ERR_error_string(ERR_get_error(), ssl_errstring);
793 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
794 return SSL_TLSEXT_ERR_NOACK;
797 /* Not sure how many of these are actually needed, since SSL object
798 already exists. Might even need this selfsame callback, for reneg? */
800 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
801 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
802 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
803 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
804 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
805 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
806 if (cbinfo->server_cipher_list)
807 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
809 if (cbinfo->u_ocsp.server.file)
811 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
812 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
816 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
817 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
819 /* do this after setup_certs, because this can require the certs for verifying
821 rc = tls_expand_session_files(server_sni, cbinfo);
822 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
824 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
825 return SSL_TLSEXT_ERR_NOACK;
827 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
828 SSL_set_SSL_CTX(s, server_sni);
830 return SSL_TLSEXT_ERR_OK;
832 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
839 /*************************************************
840 * Callback to handle OCSP Stapling *
841 *************************************************/
843 /* Called when acting as server during the TLS session setup if the client
844 requests OCSP information with a Certificate Status Request.
846 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
852 tls_server_stapling_cb(SSL *s, void *arg)
854 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
855 uschar *response_der;
856 int response_der_len;
859 debug_printf("Received TLS status request (OCSP stapling); %s response.",
860 cbinfo->u_ocsp.server.response ? "have" : "lack");
862 tls_in.ocsp = OCSP_NOT_RESP;
863 if (!cbinfo->u_ocsp.server.response)
864 return SSL_TLSEXT_ERR_NOACK;
867 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
869 if (response_der_len <= 0)
870 return SSL_TLSEXT_ERR_NOACK;
872 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
873 tls_in.ocsp = OCSP_VFIED;
874 return SSL_TLSEXT_ERR_OK;
879 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
881 BIO_printf(bp, "\t%s: ", str);
882 ASN1_GENERALIZEDTIME_print(bp, time);
887 tls_client_stapling_cb(SSL *s, void *arg)
889 tls_ext_ctx_cb * cbinfo = arg;
890 const unsigned char * p;
896 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
897 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
900 /* Expect this when we requested ocsp but got none */
901 if ( cbinfo->u_ocsp.client.verify_required
902 && log_extra_selector & LX_tls_cipher)
903 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
905 DEBUG(D_tls) debug_printf(" null\n");
906 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
909 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
911 tls_out.ocsp = OCSP_FAILED;
912 if (log_extra_selector & LX_tls_cipher)
913 log_write(0, LOG_MAIN, "Received TLS status response, parse error");
915 DEBUG(D_tls) debug_printf(" parse error\n");
919 if(!(bs = OCSP_response_get1_basic(rsp)))
921 tls_out.ocsp = OCSP_FAILED;
922 if (log_extra_selector & LX_tls_cipher)
923 log_write(0, LOG_MAIN, "Received TLS status response, error parsing response");
925 DEBUG(D_tls) debug_printf(" error parsing response\n");
926 OCSP_RESPONSE_free(rsp);
930 /* We'd check the nonce here if we'd put one in the request. */
931 /* However that would defeat cacheability on the server so we don't. */
933 /* This section of code reworked from OpenSSL apps source;
934 The OpenSSL Project retains copyright:
935 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
940 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
942 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
944 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
946 /* Use the chain that verified the server cert to verify the stapled info */
947 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
949 if ((i = OCSP_basic_verify(bs, NULL,
950 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
952 tls_out.ocsp = OCSP_FAILED;
953 BIO_printf(bp, "OCSP response verify failure\n");
954 ERR_print_errors(bp);
955 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
959 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
962 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
963 OCSP_SINGLERESP * single;
965 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
967 tls_out.ocsp = OCSP_FAILED;
968 log_write(0, LOG_MAIN, "OCSP stapling "
969 "with multiple responses not handled");
970 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
973 single = OCSP_resp_get0(bs, 0);
974 status = OCSP_single_get0_status(single, &reason, &rev,
978 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
979 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
980 if (!OCSP_check_validity(thisupd, nextupd,
981 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
983 tls_out.ocsp = OCSP_FAILED;
984 DEBUG(D_tls) ERR_print_errors(bp);
985 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
986 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
990 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
991 OCSP_cert_status_str(status));
994 case V_OCSP_CERTSTATUS_GOOD:
995 tls_out.ocsp = OCSP_VFIED;
998 case V_OCSP_CERTSTATUS_REVOKED:
999 tls_out.ocsp = OCSP_FAILED;
1000 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1001 reason != -1 ? "; reason: " : "",
1002 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1003 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1004 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1007 tls_out.ocsp = OCSP_FAILED;
1008 log_write(0, LOG_MAIN,
1009 "Server certificate status unknown, in OCSP stapling");
1010 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1018 OCSP_RESPONSE_free(rsp);
1021 #endif /*!DISABLE_OCSP*/
1024 /*************************************************
1025 * Initialize for TLS *
1026 *************************************************/
1028 /* Called from both server and client code, to do preliminary initialization
1029 of the library. We allocate and return a context structure.
1032 ctxp returned SSL context
1033 host connected host, if client; NULL if server
1034 dhparam DH parameter file
1035 certificate certificate file
1036 privatekey private key
1037 ocsp_file file of stapling info (server); flag for require ocsp (client)
1038 addr address if client; NULL if server (for some randomness)
1039 cbp place to put allocated callback context
1041 Returns: OK/DEFER/FAIL
1045 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1047 #ifndef DISABLE_OCSP
1050 address_item *addr, tls_ext_ctx_cb ** cbp)
1055 tls_ext_ctx_cb *cbinfo;
1057 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1058 cbinfo->certificate = certificate;
1059 cbinfo->privatekey = privatekey;
1060 #ifndef DISABLE_OCSP
1061 if ((cbinfo->is_server = host==NULL))
1063 cbinfo->u_ocsp.server.file = ocsp_file;
1064 cbinfo->u_ocsp.server.file_expanded = NULL;
1065 cbinfo->u_ocsp.server.response = NULL;
1068 cbinfo->u_ocsp.client.verify_store = NULL;
1070 cbinfo->dhparam = dhparam;
1071 cbinfo->server_cipher_list = NULL;
1072 cbinfo->host = host;
1074 SSL_load_error_strings(); /* basic set up */
1075 OpenSSL_add_ssl_algorithms();
1077 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1078 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1079 list of available digests. */
1080 EVP_add_digest(EVP_sha256());
1083 /* Create a context.
1084 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1085 negotiation in the different methods; as far as I can tell, the only
1086 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1087 when OpenSSL is built without SSLv2 support.
1088 By disabling with openssl_options, we can let admins re-enable with the
1091 *ctxp = SSL_CTX_new((host == NULL)?
1092 SSLv23_server_method() : SSLv23_client_method());
1094 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1096 /* It turns out that we need to seed the random number generator this early in
1097 order to get the full complement of ciphers to work. It took me roughly a day
1098 of work to discover this by experiment.
1100 On systems that have /dev/urandom, SSL may automatically seed itself from
1101 there. Otherwise, we have to make something up as best we can. Double check
1107 gettimeofday(&r.tv, NULL);
1110 RAND_seed((uschar *)(&r), sizeof(r));
1111 RAND_seed((uschar *)big_buffer, big_buffer_size);
1112 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1115 return tls_error(US"RAND_status", host,
1116 US"unable to seed random number generator");
1119 /* Set up the information callback, which outputs if debugging is at a suitable
1122 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1124 /* Automatically re-try reads/writes after renegotiation. */
1125 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1127 /* Apply administrator-supplied work-arounds.
1128 Historically we applied just one requested option,
1129 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1130 moved to an administrator-controlled list of options to specify and
1131 grandfathered in the first one as the default value for "openssl_options".
1133 No OpenSSL version number checks: the options we accept depend upon the
1134 availability of the option value macros from OpenSSL. */
1136 okay = tls_openssl_options_parse(openssl_options, &init_options);
1138 return tls_error(US"openssl_options parsing failed", host, NULL);
1142 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1143 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1144 return tls_error(string_sprintf(
1145 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1148 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1150 /* Initialize with DH parameters if supplied */
1152 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1154 /* Set up certificate and key (and perhaps OCSP info) */
1156 rc = tls_expand_session_files(*ctxp, cbinfo);
1157 if (rc != OK) return rc;
1159 /* If we need to handle SNI, do so */
1160 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1161 if (host == NULL) /* server */
1163 # ifndef DISABLE_OCSP
1164 /* We check u_ocsp.server.file, not server.response, because we care about if
1165 the option exists, not what the current expansion might be, as SNI might
1166 change the certificate and OCSP file in use between now and the time the
1167 callback is invoked. */
1168 if (cbinfo->u_ocsp.server.file)
1170 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1171 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1174 /* We always do this, so that $tls_sni is available even if not used in
1176 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1177 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1179 # ifndef DISABLE_OCSP
1181 if(ocsp_file) /* wanting stapling */
1183 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1185 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1188 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1189 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1194 #ifdef EXPERIMENTAL_CERTNAMES
1195 cbinfo->verify_cert_hostnames = NULL;
1198 /* Set up the RSA callback */
1200 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1202 /* Finally, set the timeout, and we are done */
1204 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1205 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1215 /*************************************************
1216 * Get name of cipher in use *
1217 *************************************************/
1220 Argument: pointer to an SSL structure for the connection
1221 buffer to use for answer
1223 pointer to number of bits for cipher
1228 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1230 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1231 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1232 the accessor functions use const in the prototype. */
1233 const SSL_CIPHER *c;
1236 ver = (const uschar *)SSL_get_version(ssl);
1238 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1239 SSL_CIPHER_get_bits(c, bits);
1241 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1242 SSL_CIPHER_get_name(c), *bits);
1244 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1251 /*************************************************
1252 * Set up for verifying certificates *
1253 *************************************************/
1255 /* Called by both client and server startup
1258 sctx SSL_CTX* to initialise
1259 certs certs file or NULL
1260 crl CRL file or NULL
1261 host NULL in a server; the remote host in a client
1262 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1263 otherwise passed as FALSE
1264 cert_vfy_cb Callback function for certificate verification
1266 Returns: OK/DEFER/FAIL
1270 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1271 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1273 uschar *expcerts, *expcrl;
1275 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1278 if (expcerts != NULL && *expcerts != '\0')
1280 struct stat statbuf;
1281 if (!SSL_CTX_set_default_verify_paths(sctx))
1282 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1284 if (Ustat(expcerts, &statbuf) < 0)
1286 log_write(0, LOG_MAIN|LOG_PANIC,
1287 "failed to stat %s for certificates", expcerts);
1293 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1294 { file = NULL; dir = expcerts; }
1296 { file = expcerts; dir = NULL; }
1298 /* If a certificate file is empty, the next function fails with an
1299 unhelpful error message. If we skip it, we get the correct behaviour (no
1300 certificates are recognized, but the error message is still misleading (it
1301 says no certificate was supplied.) But this is better. */
1303 if ((file == NULL || statbuf.st_size > 0) &&
1304 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1305 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1309 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
1313 /* Handle a certificate revocation list. */
1315 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1317 /* This bit of code is now the version supplied by Lars Mainka. (I have
1318 * merely reformatted it into the Exim code style.)
1320 * "From here I changed the code to add support for multiple crl's
1321 * in pem format in one file or to support hashed directory entries in
1322 * pem format instead of a file. This method now uses the library function
1323 * X509_STORE_load_locations to add the CRL location to the SSL context.
1324 * OpenSSL will then handle the verify against CA certs and CRLs by
1325 * itself in the verify callback." */
1327 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1328 if (expcrl != NULL && *expcrl != 0)
1330 struct stat statbufcrl;
1331 if (Ustat(expcrl, &statbufcrl) < 0)
1333 log_write(0, LOG_MAIN|LOG_PANIC,
1334 "failed to stat %s for certificates revocation lists", expcrl);
1339 /* is it a file or directory? */
1341 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1342 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1346 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1352 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1354 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1355 return tls_error(US"X509_STORE_load_locations", host, NULL);
1357 /* setting the flags to check against the complete crl chain */
1359 X509_STORE_set_flags(cvstore,
1360 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1364 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1366 /* If verification is optional, don't fail if no certificate */
1368 SSL_CTX_set_verify(sctx,
1369 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1378 /*************************************************
1379 * Start a TLS session in a server *
1380 *************************************************/
1382 /* This is called when Exim is running as a server, after having received
1383 the STARTTLS command. It must respond to that command, and then negotiate
1387 require_ciphers allowed ciphers
1389 Returns: OK on success
1390 DEFER for errors before the start of the negotiation
1391 FAIL for errors during the negotation; the server can't
1396 tls_server_start(const uschar *require_ciphers)
1400 tls_ext_ctx_cb *cbinfo;
1401 static uschar cipherbuf[256];
1403 /* Check for previous activation */
1405 if (tls_in.active >= 0)
1407 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1408 smtp_printf("554 Already in TLS\r\n");
1412 /* Initialize the SSL library. If it fails, it will already have logged
1415 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1416 #ifndef DISABLE_OCSP
1419 NULL, &server_static_cbinfo);
1420 if (rc != OK) return rc;
1421 cbinfo = server_static_cbinfo;
1423 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1426 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1427 were historically separated by underscores. So that I can use either form in my
1428 tests, and also for general convenience, we turn underscores into hyphens here.
1431 if (expciphers != NULL)
1433 uschar *s = expciphers;
1434 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1435 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1436 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1437 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1438 cbinfo->server_cipher_list = expciphers;
1441 /* If this is a host for which certificate verification is mandatory or
1442 optional, set up appropriately. */
1444 tls_in.certificate_verified = FALSE;
1445 server_verify_callback_called = FALSE;
1447 if (verify_check_host(&tls_verify_hosts) == OK)
1449 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1450 FALSE, verify_callback_server);
1451 if (rc != OK) return rc;
1452 server_verify_optional = FALSE;
1454 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1456 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1457 TRUE, verify_callback_server);
1458 if (rc != OK) return rc;
1459 server_verify_optional = TRUE;
1462 /* Prepare for new connection */
1464 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1466 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1468 * With the SSL_clear(), we get strange interoperability bugs with
1469 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1470 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1472 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1473 * session shutdown. In this case, we have a brand new object and there's no
1474 * obvious reason to immediately clear it. I'm guessing that this was
1475 * originally added because of incomplete initialisation which the clear fixed,
1476 * in some historic release.
1479 /* Set context and tell client to go ahead, except in the case of TLS startup
1480 on connection, where outputting anything now upsets the clients and tends to
1481 make them disconnect. We need to have an explicit fflush() here, to force out
1482 the response. Other smtp_printf() calls do not need it, because in non-TLS
1483 mode, the fflush() happens when smtp_getc() is called. */
1485 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1486 if (!tls_in.on_connect)
1488 smtp_printf("220 TLS go ahead\r\n");
1492 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1493 that the OpenSSL library doesn't. */
1495 SSL_set_wfd(server_ssl, fileno(smtp_out));
1496 SSL_set_rfd(server_ssl, fileno(smtp_in));
1497 SSL_set_accept_state(server_ssl);
1499 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1501 sigalrm_seen = FALSE;
1502 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1503 rc = SSL_accept(server_ssl);
1508 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1509 if (ERR_get_error() == 0)
1510 log_write(0, LOG_MAIN,
1511 "TLS client disconnected cleanly (rejected our certificate?)");
1515 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1517 /* TLS has been set up. Adjust the input functions to read via TLS,
1518 and initialize things. */
1520 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1521 tls_in.cipher = cipherbuf;
1526 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1527 debug_printf("Shared ciphers: %s\n", buf);
1530 /* Record the certificate we presented */
1532 X509 * crt = SSL_get_certificate(server_ssl);
1533 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1536 /* Only used by the server-side tls (tls_in), including tls_getc.
1537 Client-side (tls_out) reads (seem to?) go via
1538 smtp_read_response()/ip_recv().
1539 Hence no need to duplicate for _in and _out.
1541 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1542 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1543 ssl_xfer_eof = ssl_xfer_error = 0;
1545 receive_getc = tls_getc;
1546 receive_ungetc = tls_ungetc;
1547 receive_feof = tls_feof;
1548 receive_ferror = tls_ferror;
1549 receive_smtp_buffered = tls_smtp_buffered;
1551 tls_in.active = fileno(smtp_out);
1559 tls_client_basic_ctx_init(SSL_CTX * ctx,
1560 host_item * host, smtp_transport_options_block * ob
1561 #ifdef EXPERIMENTAL_CERTNAMES
1562 , tls_ext_ctx_cb * cbinfo
1567 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1568 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1569 the specified host patterns if one of them is defined */
1571 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1572 (verify_check_host(&ob->tls_verify_hosts) == OK))
1574 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1575 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1577 client_verify_optional = FALSE;
1579 #ifdef EXPERIMENTAL_CERTNAMES
1580 if (ob->tls_verify_cert_hostnames)
1582 if (!expand_check(ob->tls_verify_cert_hostnames,
1583 US"tls_verify_cert_hostnames",
1584 &cbinfo->verify_cert_hostnames))
1586 if (cbinfo->verify_cert_hostnames)
1587 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1588 cbinfo->verify_cert_hostnames);
1592 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1594 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1595 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1597 client_verify_optional = TRUE;
1603 /*************************************************
1604 * Start a TLS session in a client *
1605 *************************************************/
1607 /* Called from the smtp transport after STARTTLS has been accepted.
1610 fd the fd of the connection
1611 host connected host (for messages)
1612 addr the first address
1613 ob smtp transport options
1615 Returns: OK on success
1616 FAIL otherwise - note that tls_error() will not give DEFER
1617 because this is not a server
1621 tls_client_start(int fd, host_item *host, address_item *addr,
1624 smtp_transport_options_block * ob = v_ob;
1625 static uschar txt[256];
1626 uschar * expciphers;
1629 static uschar cipherbuf[256];
1631 #ifndef DISABLE_OCSP
1632 BOOL request_ocsp = FALSE;
1633 BOOL require_ocsp = FALSE;
1635 #ifdef EXPERIMENTAL_DANE
1636 dns_answer tlsa_dnsa;
1641 #ifdef EXPERIMENTAL_DANE
1642 dane_required = verify_check_this_host(&ob->hosts_require_dane, NULL,
1643 host->name, host->address, NULL) == OK;
1645 if (host->dnssec == DS_YES)
1648 || verify_check_this_host(&ob->hosts_try_dane, NULL,
1649 host->name, host->address, NULL) == OK
1652 /* move this out to host.c given the similarity to dns_lookup() ? */
1654 uschar * fullname = buffer;
1656 /* TLSA lookup string */
1657 (void)sprintf(CS buffer, "_%d._tcp.%.256s", host->port,
1660 switch (rc = dns_lookup(&tlsa_dnsa, buffer, T_TLSA, &fullname))
1663 return DEFER; /* just defer this TLS'd conn */
1669 log_write(0, LOG_MAIN, "DANE error: TLSA lookup failed");
1675 if (!dns_is_secure(&tlsa_dnsa))
1677 log_write(0, LOG_MAIN, "DANE error: TLSA lookup not DNSSEC");
1685 else if (dane_required)
1687 /*XXX a shame we only find this after making tcp & smtp connection */
1688 /* move the test earlier? */
1689 log_write(0, LOG_MAIN, "DANE error: previous lookup not DNSSEC");
1693 if (!dane) /*XXX todo: enable ocsp with dane */
1696 #ifndef DISABLE_OCSP
1698 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1699 NULL, host->name, host->address, NULL) == OK;
1700 request_ocsp = require_ocsp ? TRUE
1701 : verify_check_this_host(&ob->hosts_request_ocsp,
1702 NULL, host->name, host->address, NULL) == OK;
1706 rc = tls_init(&client_ctx, host, NULL,
1707 ob->tls_certificate, ob->tls_privatekey,
1708 #ifndef DISABLE_OCSP
1709 (void *)(long)request_ocsp,
1711 addr, &client_static_cbinfo);
1712 if (rc != OK) return rc;
1714 tls_out.certificate_verified = FALSE;
1715 client_verify_callback_called = FALSE;
1717 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1721 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1722 are separated by underscores. So that I can use either form in my tests, and
1723 also for general convenience, we turn underscores into hyphens here. */
1725 if (expciphers != NULL)
1727 uschar *s = expciphers;
1728 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1729 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1730 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1731 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1734 #ifdef EXPERIMENTAL_DANE
1737 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1739 if (!DANESSL_library_init())
1740 return tls_error(US"library init", host, NULL);
1741 if (DANESSL_CTX_init(client_ctx) <= 0)
1742 return tls_error(US"context init", host, NULL);
1748 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1749 #ifdef EXPERIMENTAL_CERTNAMES
1750 , client_static_cbinfo
1755 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1756 return tls_error(US"SSL_new", host, NULL);
1757 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1758 SSL_set_fd(client_ssl, fd);
1759 SSL_set_connect_state(client_ssl);
1763 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1765 if (tls_out.sni == NULL)
1767 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1769 else if (!Ustrlen(tls_out.sni))
1773 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1774 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1775 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1778 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1784 #ifndef DISABLE_OCSP
1785 /* Request certificate status at connection-time. If the server
1786 does OCSP stapling we will get the callback (set in tls_init()) */
1789 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1790 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1791 tls_out.ocsp = OCSP_NOT_RESP;
1795 #ifdef EXPERIMENTAL_DANE
1800 uschar * hostnames[2] = { host->name, NULL };
1802 if (DANESSL_init(client_ssl, NULL, hostnames) != 1)
1803 return tls_error(US"hostnames load", host, NULL);
1805 for (rr = dns_next_rr(&tlsa_dnsa, &dnss, RESET_ANSWERS);
1807 rr = dns_next_rr(&tlsa_dnsa, &dnss, RESET_NEXT)
1808 ) if (rr->type == T_TLSA)
1810 uschar * p = rr->data;
1811 int usage, selector, mtype;
1812 const char * mdname;
1815 GETSHORT(selector, p);
1820 default: /* log bad */ return FAIL;
1821 case 0: mdname = NULL; break;
1822 case 1: mdname = "sha256"; break;
1823 case 2: mdname = "sha512"; break;
1826 switch (DANESSL_add_tlsa(client_ssl,
1827 (uint8_t) usage, (uint8_t) selector,
1828 mdname, p, rr->size - (p - rr->data)))
1831 case 0: /* action not taken */
1832 return tls_error(US"tlsa load", host, NULL);
1840 /* There doesn't seem to be a built-in timeout on connection. */
1842 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1843 sigalrm_seen = FALSE;
1844 alarm(ob->command_timeout);
1845 rc = SSL_connect(client_ssl);
1848 #ifdef EXPERIMENTAL_DANE
1850 DANESSL_cleanup(client_ssl); /*XXX earliest possible callpoint. Too early? */
1854 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1856 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1858 /* Beware anonymous ciphers which lead to server_cert being NULL */
1859 /*XXX server_cert is never freed... use X509_free() */
1860 server_cert = SSL_get_peer_certificate (client_ssl);
1863 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1864 CS txt, sizeof(txt));
1865 tls_out.peerdn = txt; /*XXX a static buffer... */
1868 tls_out.peerdn = NULL;
1870 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1871 tls_out.cipher = cipherbuf;
1873 /* Record the certificate we presented */
1875 X509 * crt = SSL_get_certificate(client_ssl);
1876 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1879 tls_out.active = fd;
1887 /*************************************************
1888 * TLS version of getc *
1889 *************************************************/
1891 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1892 it refills the buffer via the SSL reading function.
1895 Returns: the next character or EOF
1897 Only used by the server-side TLS.
1903 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1908 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
1909 ssl_xfer_buffer, ssl_xfer_buffer_size);
1911 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1912 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1913 error = SSL_get_error(server_ssl, inbytes);
1916 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1917 closed down, not that the socket itself has been closed down. Revert to
1918 non-SSL handling. */
1920 if (error == SSL_ERROR_ZERO_RETURN)
1922 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1924 receive_getc = smtp_getc;
1925 receive_ungetc = smtp_ungetc;
1926 receive_feof = smtp_feof;
1927 receive_ferror = smtp_ferror;
1928 receive_smtp_buffered = smtp_buffered;
1930 SSL_free(server_ssl);
1934 tls_in.cipher = NULL;
1935 tls_in.peerdn = NULL;
1941 /* Handle genuine errors */
1943 else if (error == SSL_ERROR_SSL)
1945 ERR_error_string(ERR_get_error(), ssl_errstring);
1946 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
1951 else if (error != SSL_ERROR_NONE)
1953 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1958 #ifndef DISABLE_DKIM
1959 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1961 ssl_xfer_buffer_hwm = inbytes;
1962 ssl_xfer_buffer_lwm = 0;
1965 /* Something in the buffer; return next uschar */
1967 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1972 /*************************************************
1973 * Read bytes from TLS channel *
1974 *************************************************/
1981 Returns: the number of bytes read
1982 -1 after a failed read
1984 Only used by the client-side TLS.
1988 tls_read(BOOL is_server, uschar *buff, size_t len)
1990 SSL *ssl = is_server ? server_ssl : client_ssl;
1994 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1995 buff, (unsigned int)len);
1997 inbytes = SSL_read(ssl, CS buff, len);
1998 error = SSL_get_error(ssl, inbytes);
2000 if (error == SSL_ERROR_ZERO_RETURN)
2002 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2005 else if (error != SSL_ERROR_NONE)
2017 /*************************************************
2018 * Write bytes down TLS channel *
2019 *************************************************/
2023 is_server channel specifier
2027 Returns: the number of bytes after a successful write,
2028 -1 after a failed write
2030 Used by both server-side and client-side TLS.
2034 tls_write(BOOL is_server, const uschar *buff, size_t len)
2039 SSL *ssl = is_server ? server_ssl : client_ssl;
2041 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2044 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2045 outbytes = SSL_write(ssl, CS buff, left);
2046 error = SSL_get_error(ssl, outbytes);
2047 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2051 ERR_error_string(ERR_get_error(), ssl_errstring);
2052 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2055 case SSL_ERROR_NONE:
2060 case SSL_ERROR_ZERO_RETURN:
2061 log_write(0, LOG_MAIN, "SSL channel closed on write");
2064 case SSL_ERROR_SYSCALL:
2065 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2066 sender_fullhost ? sender_fullhost : US"<unknown>",
2070 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2079 /*************************************************
2080 * Close down a TLS session *
2081 *************************************************/
2083 /* This is also called from within a delivery subprocess forked from the
2084 daemon, to shut down the TLS library, without actually doing a shutdown (which
2085 would tamper with the SSL session in the parent process).
2087 Arguments: TRUE if SSL_shutdown is to be called
2090 Used by both server-side and client-side TLS.
2094 tls_close(BOOL is_server, BOOL shutdown)
2096 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2097 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2099 if (*fdp < 0) return; /* TLS was not active */
2103 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2104 SSL_shutdown(*sslp);
2116 /*************************************************
2117 * Let tls_require_ciphers be checked at startup *
2118 *************************************************/
2120 /* The tls_require_ciphers option, if set, must be something which the
2123 Returns: NULL on success, or error message
2127 tls_validate_require_cipher(void)
2130 uschar *s, *expciphers, *err;
2132 /* this duplicates from tls_init(), we need a better "init just global
2133 state, for no specific purpose" singleton function of our own */
2135 SSL_load_error_strings();
2136 OpenSSL_add_ssl_algorithms();
2137 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2138 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2139 list of available digests. */
2140 EVP_add_digest(EVP_sha256());
2143 if (!(tls_require_ciphers && *tls_require_ciphers))
2146 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2147 return US"failed to expand tls_require_ciphers";
2149 if (!(expciphers && *expciphers))
2152 /* normalisation ripped from above */
2154 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2158 ctx = SSL_CTX_new(SSLv23_server_method());
2161 ERR_error_string(ERR_get_error(), ssl_errstring);
2162 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2166 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2168 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2170 ERR_error_string(ERR_get_error(), ssl_errstring);
2171 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2182 /*************************************************
2183 * Report the library versions. *
2184 *************************************************/
2186 /* There have historically been some issues with binary compatibility in
2187 OpenSSL libraries; if Exim (like many other applications) is built against
2188 one version of OpenSSL but the run-time linker picks up another version,
2189 it can result in serious failures, including crashing with a SIGSEGV. So
2190 report the version found by the compiler and the run-time version.
2192 Note: some OS vendors backport security fixes without changing the version
2193 number/string, and the version date remains unchanged. The _build_ date
2194 will change, so we can more usefully assist with version diagnosis by also
2195 reporting the build date.
2197 Arguments: a FILE* to print the results to
2202 tls_version_report(FILE *f)
2204 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2207 OPENSSL_VERSION_TEXT,
2208 SSLeay_version(SSLEAY_VERSION),
2209 SSLeay_version(SSLEAY_BUILT_ON));
2210 /* third line is 38 characters for the %s and the line is 73 chars long;
2211 the OpenSSL output includes a "built on: " prefix already. */
2217 /*************************************************
2218 * Random number generation *
2219 *************************************************/
2221 /* Pseudo-random number generation. The result is not expected to be
2222 cryptographically strong but not so weak that someone will shoot themselves
2223 in the foot using it as a nonce in input in some email header scheme or
2224 whatever weirdness they'll twist this into. The result should handle fork()
2225 and avoid repeating sequences. OpenSSL handles that for us.
2229 Returns a random number in range [0, max-1]
2233 vaguely_random_number(int max)
2237 static pid_t pidlast = 0;
2240 uschar smallbuf[sizeof(r)];
2246 if (pidnow != pidlast)
2248 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2249 is unique for each thread", this doesn't apparently apply across processes,
2250 so our own warning from vaguely_random_number_fallback() applies here too.
2251 Fix per PostgreSQL. */
2257 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2261 gettimeofday(&r.tv, NULL);
2264 RAND_seed((uschar *)(&r), sizeof(r));
2266 /* We're after pseudo-random, not random; if we still don't have enough data
2267 in the internal PRNG then our options are limited. We could sleep and hope
2268 for entropy to come along (prayer technique) but if the system is so depleted
2269 in the first place then something is likely to just keep taking it. Instead,
2270 we'll just take whatever little bit of pseudo-random we can still manage to
2273 needed_len = sizeof(r);
2274 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2275 asked for a number less than 10. */
2276 for (r = max, i = 0; r; ++i)
2282 /* We do not care if crypto-strong */
2283 i = RAND_pseudo_bytes(smallbuf, needed_len);
2287 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2288 return vaguely_random_number_fallback(max);
2292 for (p = smallbuf; needed_len; --needed_len, ++p)
2298 /* We don't particularly care about weighted results; if someone wants
2299 smooth distribution and cares enough then they should submit a patch then. */
2306 /*************************************************
2307 * OpenSSL option parse *
2308 *************************************************/
2310 /* Parse one option for tls_openssl_options_parse below
2313 name one option name
2314 value place to store a value for it
2315 Returns success or failure in parsing
2318 struct exim_openssl_option {
2322 /* We could use a macro to expand, but we need the ifdef and not all the
2323 options document which version they were introduced in. Policylet: include
2324 all options unless explicitly for DTLS, let the administrator choose which
2327 This list is current as of:
2329 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2331 static struct exim_openssl_option exim_openssl_options[] = {
2332 /* KEEP SORTED ALPHABETICALLY! */
2334 { US"all", SSL_OP_ALL },
2336 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2337 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2339 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2340 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2342 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2343 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2345 #ifdef SSL_OP_EPHEMERAL_RSA
2346 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2348 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2349 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2351 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2352 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2354 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2355 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2357 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2358 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2360 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2361 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2363 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2364 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2366 #ifdef SSL_OP_NO_COMPRESSION
2367 { US"no_compression", SSL_OP_NO_COMPRESSION },
2369 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2370 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2372 #ifdef SSL_OP_NO_SSLv2
2373 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2375 #ifdef SSL_OP_NO_SSLv3
2376 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2378 #ifdef SSL_OP_NO_TICKET
2379 { US"no_ticket", SSL_OP_NO_TICKET },
2381 #ifdef SSL_OP_NO_TLSv1
2382 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2384 #ifdef SSL_OP_NO_TLSv1_1
2385 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2386 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2387 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2389 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2392 #ifdef SSL_OP_NO_TLSv1_2
2393 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2395 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2396 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2398 #ifdef SSL_OP_SINGLE_DH_USE
2399 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2401 #ifdef SSL_OP_SINGLE_ECDH_USE
2402 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2404 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2405 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2407 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2408 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2410 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2411 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2413 #ifdef SSL_OP_TLS_D5_BUG
2414 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2416 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2417 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2420 static int exim_openssl_options_size =
2421 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2425 tls_openssl_one_option_parse(uschar *name, long *value)
2428 int last = exim_openssl_options_size;
2429 while (last > first)
2431 int middle = (first + last)/2;
2432 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2435 *value = exim_openssl_options[middle].value;
2449 /*************************************************
2450 * OpenSSL option parsing logic *
2451 *************************************************/
2453 /* OpenSSL has a number of compatibility options which an administrator might
2454 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2455 we look like log_selector.
2458 option_spec the administrator-supplied string of options
2459 results ptr to long storage for the options bitmap
2460 Returns success or failure
2464 tls_openssl_options_parse(uschar *option_spec, long *results)
2469 BOOL adding, item_parsed;
2472 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2473 * from default because it increases BEAST susceptibility. */
2474 #ifdef SSL_OP_NO_SSLv2
2475 result |= SSL_OP_NO_SSLv2;
2478 if (option_spec == NULL)
2484 for (s=option_spec; *s != '\0'; /**/)
2486 while (isspace(*s)) ++s;
2489 if (*s != '+' && *s != '-')
2491 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2492 "+ or - expected but found \"%s\"\n", s);
2495 adding = *s++ == '+';
2496 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2499 item_parsed = tls_openssl_one_option_parse(s, &item);
2502 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2505 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2506 adding ? "adding" : "removing", result, item, s);
2521 /* End of tls-openssl.c */