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>
28 #ifdef EXPERIMENTAL_DANE
34 # define EXIM_OCSP_SKEW_SECONDS (300L)
35 # define EXIM_OCSP_MAX_AGE (-1L)
38 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
39 # define EXIM_HAVE_OPENSSL_TLSEXT
42 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
43 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
47 /* Structure for collecting random data for seeding. */
49 typedef struct randstuff {
54 /* Local static variables */
56 static BOOL client_verify_callback_called = FALSE;
57 static BOOL server_verify_callback_called = FALSE;
58 static const uschar *sid_ctx = US"exim";
60 /* We have three different contexts to care about.
62 Simple case: client, `client_ctx`
63 As a client, we can be doing a callout or cut-through delivery while receiving
64 a message. So we have a client context, which should have options initialised
65 from the SMTP Transport.
68 There are two cases: with and without ServerNameIndication from the client.
69 Given TLS SNI, we can be using different keys, certs and various other
70 configuration settings, because they're re-expanded with $tls_sni set. This
71 allows vhosting with TLS. This SNI is sent in the handshake.
72 A client might not send SNI, so we need a fallback, and an initial setup too.
73 So as a server, we start out using `server_ctx`.
74 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
75 `server_sni` from `server_ctx` and then initialise settings by re-expanding
79 static SSL_CTX *client_ctx = NULL;
80 static SSL_CTX *server_ctx = NULL;
81 static SSL *client_ssl = NULL;
82 static SSL *server_ssl = NULL;
84 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
85 static SSL_CTX *server_sni = NULL;
88 static char ssl_errstring[256];
90 static int ssl_session_timeout = 200;
91 static BOOL client_verify_optional = FALSE;
92 static BOOL server_verify_optional = FALSE;
94 static BOOL reexpand_tls_files_for_sni = FALSE;
97 typedef struct tls_ext_ctx_cb {
105 uschar *file_expanded;
106 OCSP_RESPONSE *response;
109 X509_STORE *verify_store; /* non-null if status requested */
110 BOOL verify_required;
115 /* these are cached from first expand */
116 uschar *server_cipher_list;
117 /* only passed down to tls_error: */
120 #ifdef EXPERIMENTAL_CERTNAMES
121 uschar * verify_cert_hostnames;
123 #ifdef EXPERIMENTAL_EVENT
124 uschar * event_action;
128 /* should figure out a cleanup of API to handle state preserved per
129 implementation, for various reasons, which can be void * in the APIs.
130 For now, we hack around it. */
131 tls_ext_ctx_cb *client_static_cbinfo = NULL;
132 tls_ext_ctx_cb *server_static_cbinfo = NULL;
135 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
136 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
139 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
140 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
143 static int tls_server_stapling_cb(SSL *s, void *arg);
147 /*************************************************
149 *************************************************/
151 /* Called from lots of places when errors occur before actually starting to do
152 the TLS handshake, that is, while the session is still in clear. Always returns
153 DEFER for a server and FAIL for a client so that most calls can use "return
154 tls_error(...)" to do this processing and then give an appropriate return. A
155 single function is used for both server and client, because it is called from
156 some shared functions.
159 prefix text to include in the logged error
160 host NULL if setting up a server;
161 the connected host if setting up a client
162 msg error message or NULL if we should ask OpenSSL
164 Returns: OK/DEFER/FAIL
168 tls_error(uschar *prefix, host_item *host, uschar *msg)
172 ERR_error_string(ERR_get_error(), ssl_errstring);
173 msg = (uschar *)ssl_errstring;
178 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
179 host->name, host->address, prefix, msg);
184 uschar *conn_info = smtp_get_connection_info();
185 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
187 /* I'd like to get separated H= here, but too hard for now */
188 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
189 conn_info, prefix, msg);
196 /*************************************************
197 * Callback to generate RSA key *
198 *************************************************/
206 Returns: pointer to generated key
210 rsa_callback(SSL *s, int export, int keylength)
213 export = export; /* Shut picky compilers up */
214 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
215 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
218 ERR_error_string(ERR_get_error(), ssl_errstring);
219 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
231 x509_store_dump_cert_s_names(X509_STORE * store)
233 STACK_OF(X509_OBJECT) * roots= store->objs;
235 static uschar name[256];
237 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
239 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
240 if(tmp_obj->type == X509_LU_X509)
242 X509 * current_cert= tmp_obj->data.x509;
243 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
244 debug_printf(" %s\n", name);
252 /*************************************************
253 * Callback for verification *
254 *************************************************/
256 /* The SSL library does certificate verification if set up to do so. This
257 callback has the current yes/no state is in "state". If verification succeeded,
258 we set up the tls_peerdn string. If verification failed, what happens depends
259 on whether the client is required to present a verifiable certificate or not.
261 If verification is optional, we change the state to yes, but still log the
262 verification error. For some reason (it really would help to have proper
263 documentation of OpenSSL), this callback function then gets called again, this
264 time with state = 1. In fact, that's useful, because we can set up the peerdn
265 value, but we must take care not to set the private verified flag on the second
268 Note: this function is not called if the client fails to present a certificate
269 when asked. We get here only if a certificate has been received. Handling of
270 optional verification for this case is done when requesting SSL to verify, by
271 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
273 May be called multiple times for different issues with a certificate, even
274 for a given "depth" in the certificate chain.
277 state current yes/no state as 1/0
278 x509ctx certificate information.
279 client TRUE for client startup, FALSE for server startup
281 Returns: 1 if verified, 0 if not
285 verify_callback(int state, X509_STORE_CTX *x509ctx,
286 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
288 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
289 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
290 static uschar txt[256];
292 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
296 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
298 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
300 tlsp->certificate_verified = FALSE;
304 tlsp->peercert = X509_dup(cert);
305 return 0; /* reject */
307 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
308 "tls_try_verify_hosts)\n");
313 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
315 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
316 { /* client, wanting stapling */
317 /* Add the server cert's signing chain as the one
318 for the verification of the OCSP stapled information. */
320 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
325 #ifdef EXPERIMENTAL_EVENT
326 if (tlsp == &tls_out && client_static_cbinfo->event_action)
328 tlsp->peercert = X509_dup(cert);
329 if (event_raise(client_static_cbinfo->event_action,
330 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
332 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
333 "depth=%d cert=%s", depth, txt);
334 tlsp->certificate_verified = FALSE;
336 return 0; /* reject */
338 X509_free(tlsp->peercert);
339 tlsp->peercert = NULL;
345 #ifdef EXPERIMENTAL_CERTNAMES
346 uschar * verify_cert_hostnames;
350 tlsp->peercert = X509_dup(cert);
352 #ifdef EXPERIMENTAL_CERTNAMES
353 if ( tlsp == &tls_out
354 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
355 /* client, wanting hostname check */
357 # if OPENSSL_VERSION_NUMBER >= 0x010100000L || OPENSSL_VERSION_NUMBER >= 0x010002000L
358 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
359 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
363 uschar * list = verify_cert_hostnames;
366 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
367 if ((rc = X509_check_host(cert, name, 0,
368 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)))
372 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
379 log_write(0, LOG_MAIN,
380 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
381 return 0; /* reject */
385 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
387 log_write(0, LOG_MAIN,
388 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
389 return 0; /* reject */
392 #endif /*EXPERIMENTAL_CERTNAMES*/
394 #ifdef EXPERIMENTAL_EVENT
395 if (tlsp == &tls_out)
397 if (event_raise(client_static_cbinfo->event_action,
398 US"tls:cert", US"0") == DEFER)
400 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
401 "depth=0 cert=%s", txt);
402 tlsp->certificate_verified = FALSE;
404 return 0; /* reject */
409 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
410 *calledp ? "" : " authenticated", txt);
411 if (!*calledp) tlsp->certificate_verified = TRUE;
415 return 1; /* accept, at least for this level */
419 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
421 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
425 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
427 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
431 #ifdef EXPERIMENTAL_DANE
433 /* This gets called *by* the dane library verify callback, which interposes
437 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
439 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
440 static uschar txt[256];
441 #ifdef EXPERIMENTAL_EVENT
442 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
445 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
447 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
448 tls_out.peerdn = txt;
449 tls_out.peercert = X509_dup(cert);
451 #ifdef EXPERIMENTAL_EVENT
452 if (client_static_cbinfo->event_action)
454 if (event_raise(client_static_cbinfo->event_action,
455 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
457 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
458 "depth=%d cert=%s", depth, txt);
459 tls_out.certificate_verified = FALSE;
460 return 0; /* reject */
464 X509_free(tls_out.peercert);
465 tls_out.peercert = NULL;
471 tls_out.dane_verified =
472 tls_out.certificate_verified = TRUE;
476 #endif /*EXPERIMENTAL_DANE*/
479 /*************************************************
480 * Information callback *
481 *************************************************/
483 /* The SSL library functions call this from time to time to indicate what they
484 are doing. We copy the string to the debugging output when TLS debugging has
496 info_callback(SSL *s, int where, int ret)
500 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
505 /*************************************************
506 * Initialize for DH *
507 *************************************************/
509 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
512 dhparam DH parameter file or fixed parameter identity string
513 host connected host, if client; NULL if server
515 Returns: TRUE if OK (nothing to set up, or setup worked)
519 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
526 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
529 if (!dhexpanded || !*dhexpanded)
530 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
531 else if (dhexpanded[0] == '/')
533 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
535 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
536 host, US strerror(errno));
542 if (Ustrcmp(dhexpanded, "none") == 0)
544 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
548 if (!(pem = std_dh_prime_named(dhexpanded)))
550 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
551 host, US strerror(errno));
554 bio = BIO_new_mem_buf(CS pem, -1);
557 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
560 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
565 /* Even if it is larger, we silently return success rather than cause things
566 * to fail out, so that a too-large DH will not knock out all TLS; it's a
567 * debatable choice. */
568 if ((8*DH_size(dh)) > tls_dh_max_bits)
571 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
572 8*DH_size(dh), tls_dh_max_bits);
576 SSL_CTX_set_tmp_dh(sctx, dh);
578 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
579 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
592 /*************************************************
593 * Load OCSP information into state *
594 *************************************************/
596 /* Called to load the server OCSP response from the given file into memory, once
597 caller has determined this is needed. Checks validity. Debugs a message
600 ASSUMES: single response, for single cert.
603 sctx the SSL_CTX* to update
604 cbinfo various parts of session state
605 expanded the filename putatively holding an OCSP response
610 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
614 OCSP_BASICRESP *basic_response;
615 OCSP_SINGLERESP *single_response;
616 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
618 unsigned long verify_flags;
619 int status, reason, i;
621 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
622 if (cbinfo->u_ocsp.server.response)
624 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
625 cbinfo->u_ocsp.server.response = NULL;
628 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
631 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
632 cbinfo->u_ocsp.server.file_expanded);
636 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
640 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
644 status = OCSP_response_status(resp);
645 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
647 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
648 OCSP_response_status_str(status), status);
652 basic_response = OCSP_response_get1_basic(resp);
656 debug_printf("OCSP response parse error: unable to extract basic response.\n");
660 store = SSL_CTX_get_cert_store(sctx);
661 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
663 /* May need to expose ability to adjust those flags?
664 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
665 OCSP_TRUSTOTHER OCSP_NOINTERN */
667 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
671 ERR_error_string(ERR_get_error(), ssl_errstring);
672 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
677 /* Here's the simplifying assumption: there's only one response, for the
678 one certificate we use, and nothing for anything else in a chain. If this
679 proves false, we need to extract a cert id from our issued cert
680 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
681 right cert in the stack and then calls OCSP_single_get0_status()).
683 I'm hoping to avoid reworking a bunch more of how we handle state here. */
684 single_response = OCSP_resp_get0(basic_response, 0);
685 if (!single_response)
688 debug_printf("Unable to get first response from OCSP basic response.\n");
692 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
693 if (status != V_OCSP_CERTSTATUS_GOOD)
695 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
696 OCSP_cert_status_str(status), status,
697 OCSP_crl_reason_str(reason), reason);
701 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
703 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
708 cbinfo->u_ocsp.server.response = resp;
712 if (running_in_test_harness)
714 extern char ** environ;
716 for (p = USS environ; *p != NULL; p++)
717 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
719 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
720 goto supply_response;
725 #endif /*!DISABLE_OCSP*/
730 /*************************************************
731 * Expand key and cert file specs *
732 *************************************************/
734 /* Called once during tls_init and possibly again during TLS setup, for a
735 new context, if Server Name Indication was used and tls_sni was seen in
736 the certificate string.
739 sctx the SSL_CTX* to update
740 cbinfo various parts of session state
742 Returns: OK/DEFER/FAIL
746 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
750 if (cbinfo->certificate == NULL)
753 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
754 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
755 Ustrstr(cbinfo->certificate, US"tls_out_sni")
757 reexpand_tls_files_for_sni = TRUE;
759 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
762 if (expanded != NULL)
764 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
765 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
766 return tls_error(string_sprintf(
767 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
771 if (cbinfo->privatekey != NULL &&
772 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
775 /* If expansion was forced to fail, key_expanded will be NULL. If the result
776 of the expansion is an empty string, ignore it also, and assume the private
777 key is in the same file as the certificate. */
779 if (expanded != NULL && *expanded != 0)
781 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
782 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
783 return tls_error(string_sprintf(
784 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
788 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
790 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
793 if (expanded != NULL && *expanded != 0)
795 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
796 if (cbinfo->u_ocsp.server.file_expanded &&
797 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
800 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
802 ocsp_load_response(sctx, cbinfo, expanded);
814 /*************************************************
815 * Callback to handle SNI *
816 *************************************************/
818 /* Called when acting as server during the TLS session setup if a Server Name
819 Indication extension was sent by the client.
821 API documentation is OpenSSL s_server.c implementation.
824 s SSL* of the current session
825 ad unknown (part of OpenSSL API) (unused)
826 arg Callback of "our" registered data
828 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
831 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
833 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
835 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
836 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
838 int old_pool = store_pool;
841 return SSL_TLSEXT_ERR_OK;
843 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
844 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
846 /* Make the extension value available for expansion */
847 store_pool = POOL_PERM;
848 tls_in.sni = string_copy(US servername);
849 store_pool = old_pool;
851 if (!reexpand_tls_files_for_sni)
852 return SSL_TLSEXT_ERR_OK;
854 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
855 not confident that memcpy wouldn't break some internal reference counting.
856 Especially since there's a references struct member, which would be off. */
858 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
860 ERR_error_string(ERR_get_error(), ssl_errstring);
861 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
862 return SSL_TLSEXT_ERR_NOACK;
865 /* Not sure how many of these are actually needed, since SSL object
866 already exists. Might even need this selfsame callback, for reneg? */
868 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
869 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
870 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
871 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
872 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
873 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
874 if (cbinfo->server_cipher_list)
875 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
877 if (cbinfo->u_ocsp.server.file)
879 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
880 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
884 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
885 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
887 /* do this after setup_certs, because this can require the certs for verifying
889 rc = tls_expand_session_files(server_sni, cbinfo);
890 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
892 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
893 return SSL_TLSEXT_ERR_NOACK;
895 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
896 SSL_set_SSL_CTX(s, server_sni);
898 return SSL_TLSEXT_ERR_OK;
900 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
907 /*************************************************
908 * Callback to handle OCSP Stapling *
909 *************************************************/
911 /* Called when acting as server during the TLS session setup if the client
912 requests OCSP information with a Certificate Status Request.
914 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
920 tls_server_stapling_cb(SSL *s, void *arg)
922 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
923 uschar *response_der;
924 int response_der_len;
927 debug_printf("Received TLS status request (OCSP stapling); %s response.",
928 cbinfo->u_ocsp.server.response ? "have" : "lack");
930 tls_in.ocsp = OCSP_NOT_RESP;
931 if (!cbinfo->u_ocsp.server.response)
932 return SSL_TLSEXT_ERR_NOACK;
935 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
937 if (response_der_len <= 0)
938 return SSL_TLSEXT_ERR_NOACK;
940 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
941 tls_in.ocsp = OCSP_VFIED;
942 return SSL_TLSEXT_ERR_OK;
947 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
949 BIO_printf(bp, "\t%s: ", str);
950 ASN1_GENERALIZEDTIME_print(bp, time);
955 tls_client_stapling_cb(SSL *s, void *arg)
957 tls_ext_ctx_cb * cbinfo = arg;
958 const unsigned char * p;
964 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
965 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
968 /* Expect this when we requested ocsp but got none */
969 if ( cbinfo->u_ocsp.client.verify_required
970 && log_extra_selector & LX_tls_cipher)
971 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
973 DEBUG(D_tls) debug_printf(" null\n");
974 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
977 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
979 tls_out.ocsp = OCSP_FAILED;
980 if (log_extra_selector & LX_tls_cipher)
981 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
983 DEBUG(D_tls) debug_printf(" parse error\n");
987 if(!(bs = OCSP_response_get1_basic(rsp)))
989 tls_out.ocsp = OCSP_FAILED;
990 if (log_extra_selector & LX_tls_cipher)
991 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
993 DEBUG(D_tls) debug_printf(" error parsing response\n");
994 OCSP_RESPONSE_free(rsp);
998 /* We'd check the nonce here if we'd put one in the request. */
999 /* However that would defeat cacheability on the server so we don't. */
1001 /* This section of code reworked from OpenSSL apps source;
1002 The OpenSSL Project retains copyright:
1003 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1008 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1010 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1012 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1014 /* Use the chain that verified the server cert to verify the stapled info */
1015 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1017 if ((i = OCSP_basic_verify(bs, NULL,
1018 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1020 tls_out.ocsp = OCSP_FAILED;
1021 if (log_extra_selector & LX_tls_cipher)
1022 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1023 BIO_printf(bp, "OCSP response verify failure\n");
1024 ERR_print_errors(bp);
1025 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1029 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1032 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1033 OCSP_SINGLERESP * single;
1035 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1037 tls_out.ocsp = OCSP_FAILED;
1038 log_write(0, LOG_MAIN, "OCSP stapling "
1039 "with multiple responses not handled");
1040 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1043 single = OCSP_resp_get0(bs, 0);
1044 status = OCSP_single_get0_status(single, &reason, &rev,
1045 &thisupd, &nextupd);
1048 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1049 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1050 if (!OCSP_check_validity(thisupd, nextupd,
1051 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1053 tls_out.ocsp = OCSP_FAILED;
1054 DEBUG(D_tls) ERR_print_errors(bp);
1055 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1056 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1060 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1061 OCSP_cert_status_str(status));
1064 case V_OCSP_CERTSTATUS_GOOD:
1065 tls_out.ocsp = OCSP_VFIED;
1068 case V_OCSP_CERTSTATUS_REVOKED:
1069 tls_out.ocsp = OCSP_FAILED;
1070 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1071 reason != -1 ? "; reason: " : "",
1072 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1073 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1074 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1077 tls_out.ocsp = OCSP_FAILED;
1078 log_write(0, LOG_MAIN,
1079 "Server certificate status unknown, in OCSP stapling");
1080 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1088 OCSP_RESPONSE_free(rsp);
1091 #endif /*!DISABLE_OCSP*/
1094 /*************************************************
1095 * Initialize for TLS *
1096 *************************************************/
1098 /* Called from both server and client code, to do preliminary initialization
1099 of the library. We allocate and return a context structure.
1102 ctxp returned SSL context
1103 host connected host, if client; NULL if server
1104 dhparam DH parameter file
1105 certificate certificate file
1106 privatekey private key
1107 ocsp_file file of stapling info (server); flag for require ocsp (client)
1108 addr address if client; NULL if server (for some randomness)
1109 cbp place to put allocated callback context
1111 Returns: OK/DEFER/FAIL
1115 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1117 #ifndef DISABLE_OCSP
1120 address_item *addr, tls_ext_ctx_cb ** cbp)
1125 tls_ext_ctx_cb * cbinfo;
1127 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1128 cbinfo->certificate = certificate;
1129 cbinfo->privatekey = privatekey;
1130 #ifndef DISABLE_OCSP
1131 if ((cbinfo->is_server = host==NULL))
1133 cbinfo->u_ocsp.server.file = ocsp_file;
1134 cbinfo->u_ocsp.server.file_expanded = NULL;
1135 cbinfo->u_ocsp.server.response = NULL;
1138 cbinfo->u_ocsp.client.verify_store = NULL;
1140 cbinfo->dhparam = dhparam;
1141 cbinfo->server_cipher_list = NULL;
1142 cbinfo->host = host;
1143 #ifdef EXPERIMENTAL_EVENT
1144 cbinfo->event_action = NULL;
1147 SSL_load_error_strings(); /* basic set up */
1148 OpenSSL_add_ssl_algorithms();
1150 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1151 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1152 list of available digests. */
1153 EVP_add_digest(EVP_sha256());
1156 /* Create a context.
1157 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1158 negotiation in the different methods; as far as I can tell, the only
1159 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1160 when OpenSSL is built without SSLv2 support.
1161 By disabling with openssl_options, we can let admins re-enable with the
1164 *ctxp = SSL_CTX_new((host == NULL)?
1165 SSLv23_server_method() : SSLv23_client_method());
1167 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1169 /* It turns out that we need to seed the random number generator this early in
1170 order to get the full complement of ciphers to work. It took me roughly a day
1171 of work to discover this by experiment.
1173 On systems that have /dev/urandom, SSL may automatically seed itself from
1174 there. Otherwise, we have to make something up as best we can. Double check
1180 gettimeofday(&r.tv, NULL);
1183 RAND_seed((uschar *)(&r), sizeof(r));
1184 RAND_seed((uschar *)big_buffer, big_buffer_size);
1185 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1188 return tls_error(US"RAND_status", host,
1189 US"unable to seed random number generator");
1192 /* Set up the information callback, which outputs if debugging is at a suitable
1195 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1197 /* Automatically re-try reads/writes after renegotiation. */
1198 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1200 /* Apply administrator-supplied work-arounds.
1201 Historically we applied just one requested option,
1202 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1203 moved to an administrator-controlled list of options to specify and
1204 grandfathered in the first one as the default value for "openssl_options".
1206 No OpenSSL version number checks: the options we accept depend upon the
1207 availability of the option value macros from OpenSSL. */
1209 okay = tls_openssl_options_parse(openssl_options, &init_options);
1211 return tls_error(US"openssl_options parsing failed", host, NULL);
1215 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1216 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1217 return tls_error(string_sprintf(
1218 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1221 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1223 /* Initialize with DH parameters if supplied */
1225 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1227 /* Set up certificate and key (and perhaps OCSP info) */
1229 rc = tls_expand_session_files(*ctxp, cbinfo);
1230 if (rc != OK) return rc;
1232 /* If we need to handle SNI, do so */
1233 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1234 if (host == NULL) /* server */
1236 # ifndef DISABLE_OCSP
1237 /* We check u_ocsp.server.file, not server.response, because we care about if
1238 the option exists, not what the current expansion might be, as SNI might
1239 change the certificate and OCSP file in use between now and the time the
1240 callback is invoked. */
1241 if (cbinfo->u_ocsp.server.file)
1243 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1244 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1247 /* We always do this, so that $tls_sni is available even if not used in
1249 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1250 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1252 # ifndef DISABLE_OCSP
1254 if(ocsp_file) /* wanting stapling */
1256 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1258 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1261 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1262 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1267 #ifdef EXPERIMENTAL_CERTNAMES
1268 cbinfo->verify_cert_hostnames = NULL;
1271 /* Set up the RSA callback */
1273 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1275 /* Finally, set the timeout, and we are done */
1277 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1278 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1288 /*************************************************
1289 * Get name of cipher in use *
1290 *************************************************/
1293 Argument: pointer to an SSL structure for the connection
1294 buffer to use for answer
1296 pointer to number of bits for cipher
1301 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1303 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1304 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1305 the accessor functions use const in the prototype. */
1306 const SSL_CIPHER *c;
1309 ver = (const uschar *)SSL_get_version(ssl);
1311 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1312 SSL_CIPHER_get_bits(c, bits);
1314 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1315 SSL_CIPHER_get_name(c), *bits);
1317 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1324 /*************************************************
1325 * Set up for verifying certificates *
1326 *************************************************/
1328 /* Called by both client and server startup
1331 sctx SSL_CTX* to initialise
1332 certs certs file or NULL
1333 crl CRL file or NULL
1334 host NULL in a server; the remote host in a client
1335 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1336 otherwise passed as FALSE
1337 cert_vfy_cb Callback function for certificate verification
1339 Returns: OK/DEFER/FAIL
1343 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1344 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1346 uschar *expcerts, *expcrl;
1348 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1351 if (expcerts != NULL && *expcerts != '\0')
1353 struct stat statbuf;
1354 if (!SSL_CTX_set_default_verify_paths(sctx))
1355 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1357 if (Ustat(expcerts, &statbuf) < 0)
1359 log_write(0, LOG_MAIN|LOG_PANIC,
1360 "failed to stat %s for certificates", expcerts);
1366 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1367 { file = NULL; dir = expcerts; }
1369 { file = expcerts; dir = NULL; }
1371 /* If a certificate file is empty, the next function fails with an
1372 unhelpful error message. If we skip it, we get the correct behaviour (no
1373 certificates are recognized, but the error message is still misleading (it
1374 says no certificate was supplied.) But this is better. */
1376 if ((file == NULL || statbuf.st_size > 0) &&
1377 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1378 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1380 /* Load the list of CAs for which we will accept certs, for sending
1381 to the client. This is only for the one-file tls_verify_certificates
1383 If a list isn't loaded into the server, but
1384 some verify locations are set, the server end appears to make
1385 a wildcard reqest for client certs.
1386 Meanwhile, the client library as deafult behaviour *ignores* the list
1387 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1388 Because of this, and that the dir variant is likely only used for
1389 the public-CA bundle (not for a private CA), not worth fixing.
1393 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1394 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1395 sk_X509_NAME_num(names));
1396 SSL_CTX_set_client_CA_list(sctx, names);
1400 /* Handle a certificate revocation list. */
1402 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1404 /* This bit of code is now the version supplied by Lars Mainka. (I have
1405 * merely reformatted it into the Exim code style.)
1407 * "From here I changed the code to add support for multiple crl's
1408 * in pem format in one file or to support hashed directory entries in
1409 * pem format instead of a file. This method now uses the library function
1410 * X509_STORE_load_locations to add the CRL location to the SSL context.
1411 * OpenSSL will then handle the verify against CA certs and CRLs by
1412 * itself in the verify callback." */
1414 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1415 if (expcrl != NULL && *expcrl != 0)
1417 struct stat statbufcrl;
1418 if (Ustat(expcrl, &statbufcrl) < 0)
1420 log_write(0, LOG_MAIN|LOG_PANIC,
1421 "failed to stat %s for certificates revocation lists", expcrl);
1426 /* is it a file or directory? */
1428 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1429 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1433 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1439 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1441 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1442 return tls_error(US"X509_STORE_load_locations", host, NULL);
1444 /* setting the flags to check against the complete crl chain */
1446 X509_STORE_set_flags(cvstore,
1447 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1451 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1453 /* If verification is optional, don't fail if no certificate */
1455 SSL_CTX_set_verify(sctx,
1456 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1465 /*************************************************
1466 * Start a TLS session in a server *
1467 *************************************************/
1469 /* This is called when Exim is running as a server, after having received
1470 the STARTTLS command. It must respond to that command, and then negotiate
1474 require_ciphers allowed ciphers
1476 Returns: OK on success
1477 DEFER for errors before the start of the negotiation
1478 FAIL for errors during the negotation; the server can't
1483 tls_server_start(const uschar *require_ciphers)
1487 tls_ext_ctx_cb *cbinfo;
1488 static uschar cipherbuf[256];
1490 /* Check for previous activation */
1492 if (tls_in.active >= 0)
1494 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1495 smtp_printf("554 Already in TLS\r\n");
1499 /* Initialize the SSL library. If it fails, it will already have logged
1502 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1503 #ifndef DISABLE_OCSP
1506 NULL, &server_static_cbinfo);
1507 if (rc != OK) return rc;
1508 cbinfo = server_static_cbinfo;
1510 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1513 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1514 were historically separated by underscores. So that I can use either form in my
1515 tests, and also for general convenience, we turn underscores into hyphens here.
1518 if (expciphers != NULL)
1520 uschar *s = expciphers;
1521 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1522 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1523 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1524 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1525 cbinfo->server_cipher_list = expciphers;
1528 /* If this is a host for which certificate verification is mandatory or
1529 optional, set up appropriately. */
1531 tls_in.certificate_verified = FALSE;
1532 #ifdef EXPERIMENTAL_DANE
1533 tls_in.dane_verified = FALSE;
1535 server_verify_callback_called = FALSE;
1537 if (verify_check_host(&tls_verify_hosts) == OK)
1539 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1540 FALSE, verify_callback_server);
1541 if (rc != OK) return rc;
1542 server_verify_optional = FALSE;
1544 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1546 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1547 TRUE, verify_callback_server);
1548 if (rc != OK) return rc;
1549 server_verify_optional = TRUE;
1552 /* Prepare for new connection */
1554 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1556 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1558 * With the SSL_clear(), we get strange interoperability bugs with
1559 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1560 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1562 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1563 * session shutdown. In this case, we have a brand new object and there's no
1564 * obvious reason to immediately clear it. I'm guessing that this was
1565 * originally added because of incomplete initialisation which the clear fixed,
1566 * in some historic release.
1569 /* Set context and tell client to go ahead, except in the case of TLS startup
1570 on connection, where outputting anything now upsets the clients and tends to
1571 make them disconnect. We need to have an explicit fflush() here, to force out
1572 the response. Other smtp_printf() calls do not need it, because in non-TLS
1573 mode, the fflush() happens when smtp_getc() is called. */
1575 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1576 if (!tls_in.on_connect)
1578 smtp_printf("220 TLS go ahead\r\n");
1582 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1583 that the OpenSSL library doesn't. */
1585 SSL_set_wfd(server_ssl, fileno(smtp_out));
1586 SSL_set_rfd(server_ssl, fileno(smtp_in));
1587 SSL_set_accept_state(server_ssl);
1589 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1591 sigalrm_seen = FALSE;
1592 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1593 rc = SSL_accept(server_ssl);
1598 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1599 if (ERR_get_error() == 0)
1600 log_write(0, LOG_MAIN,
1601 "TLS client disconnected cleanly (rejected our certificate?)");
1605 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1607 /* TLS has been set up. Adjust the input functions to read via TLS,
1608 and initialize things. */
1610 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1611 tls_in.cipher = cipherbuf;
1616 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1617 debug_printf("Shared ciphers: %s\n", buf);
1620 /* Record the certificate we presented */
1622 X509 * crt = SSL_get_certificate(server_ssl);
1623 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1626 /* Only used by the server-side tls (tls_in), including tls_getc.
1627 Client-side (tls_out) reads (seem to?) go via
1628 smtp_read_response()/ip_recv().
1629 Hence no need to duplicate for _in and _out.
1631 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1632 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1633 ssl_xfer_eof = ssl_xfer_error = 0;
1635 receive_getc = tls_getc;
1636 receive_ungetc = tls_ungetc;
1637 receive_feof = tls_feof;
1638 receive_ferror = tls_ferror;
1639 receive_smtp_buffered = tls_smtp_buffered;
1641 tls_in.active = fileno(smtp_out);
1649 tls_client_basic_ctx_init(SSL_CTX * ctx,
1650 host_item * host, smtp_transport_options_block * ob
1651 #ifdef EXPERIMENTAL_CERTNAMES
1652 , tls_ext_ctx_cb * cbinfo
1657 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1658 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1659 the specified host patterns if one of them is defined */
1661 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1662 (verify_check_host(&ob->tls_verify_hosts) == OK))
1664 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1665 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1667 client_verify_optional = FALSE;
1669 #ifdef EXPERIMENTAL_CERTNAMES
1670 if (ob->tls_verify_cert_hostnames)
1672 if (!expand_check(ob->tls_verify_cert_hostnames,
1673 US"tls_verify_cert_hostnames",
1674 &cbinfo->verify_cert_hostnames))
1676 if (cbinfo->verify_cert_hostnames)
1677 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1678 cbinfo->verify_cert_hostnames);
1682 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1684 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1685 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1687 client_verify_optional = TRUE;
1694 #ifdef EXPERIMENTAL_DANE
1696 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1700 const char * hostnames[2] = { CS host->name, NULL };
1703 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1704 return tls_error(US"hostnames load", host, NULL);
1706 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1708 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1709 ) if (rr->type == T_TLSA)
1711 uschar * p = rr->data;
1712 uint8_t usage, selector, mtype;
1713 const char * mdname;
1717 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1718 if (usage != 2 && usage != 3) continue;
1725 default: continue; /* Only match-types 0, 1, 2 are supported */
1726 case 0: mdname = NULL; break;
1727 case 1: mdname = "sha256"; break;
1728 case 2: mdname = "sha512"; break;
1732 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1735 case 0: /* action not taken */
1736 return tls_error(US"tlsa load", host, NULL);
1740 tls_out.tlsa_usage |= 1<<usage;
1746 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1749 #endif /*EXPERIMENTAL_DANE*/
1753 /*************************************************
1754 * Start a TLS session in a client *
1755 *************************************************/
1757 /* Called from the smtp transport after STARTTLS has been accepted.
1760 fd the fd of the connection
1761 host connected host (for messages)
1762 addr the first address
1763 tb transport (always smtp)
1764 tlsa_dnsa tlsa lookup, if DANE, else null
1766 Returns: OK on success
1767 FAIL otherwise - note that tls_error() will not give DEFER
1768 because this is not a server
1772 tls_client_start(int fd, host_item *host, address_item *addr,
1773 transport_instance *tb
1774 #ifdef EXPERIMENTAL_DANE
1775 , dns_answer * tlsa_dnsa
1779 smtp_transport_options_block * ob =
1780 (smtp_transport_options_block *)tb->options_block;
1781 static uschar txt[256];
1782 uschar * expciphers;
1785 static uschar cipherbuf[256];
1787 #ifndef DISABLE_OCSP
1788 BOOL request_ocsp = FALSE;
1789 BOOL require_ocsp = FALSE;
1792 #ifdef EXPERIMENTAL_DANE
1793 tls_out.tlsa_usage = 0;
1796 #ifndef DISABLE_OCSP
1798 # ifdef EXPERIMENTAL_DANE
1800 && ob->hosts_request_ocsp[0] == '*'
1801 && ob->hosts_request_ocsp[1] == '\0'
1804 /* Unchanged from default. Use a safer one under DANE */
1805 request_ocsp = TRUE;
1806 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1807 " {= {4}{$tls_out_tlsa_usage}} } "
1812 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1813 NULL, host->name, host->address, NULL) == OK))
1814 request_ocsp = TRUE;
1816 # ifdef EXPERIMENTAL_DANE
1819 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1820 NULL, host->name, host->address, NULL) == OK;
1824 rc = tls_init(&client_ctx, host, NULL,
1825 ob->tls_certificate, ob->tls_privatekey,
1826 #ifndef DISABLE_OCSP
1827 (void *)(long)request_ocsp,
1829 addr, &client_static_cbinfo);
1830 if (rc != OK) return rc;
1832 tls_out.certificate_verified = FALSE;
1833 client_verify_callback_called = FALSE;
1835 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1839 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1840 are separated by underscores. So that I can use either form in my tests, and
1841 also for general convenience, we turn underscores into hyphens here. */
1843 if (expciphers != NULL)
1845 uschar *s = expciphers;
1846 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1847 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1848 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1849 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1852 #ifdef EXPERIMENTAL_DANE
1855 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1857 if (!DANESSL_library_init())
1858 return tls_error(US"library init", host, NULL);
1859 if (DANESSL_CTX_init(client_ctx) <= 0)
1860 return tls_error(US"context init", host, NULL);
1866 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1867 #ifdef EXPERIMENTAL_CERTNAMES
1868 , client_static_cbinfo
1873 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1874 return tls_error(US"SSL_new", host, NULL);
1875 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1876 SSL_set_fd(client_ssl, fd);
1877 SSL_set_connect_state(client_ssl);
1881 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1883 if (tls_out.sni == NULL)
1885 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1887 else if (!Ustrlen(tls_out.sni))
1891 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1892 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1893 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1896 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1902 #ifdef EXPERIMENTAL_DANE
1904 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1908 #ifndef DISABLE_OCSP
1909 /* Request certificate status at connection-time. If the server
1910 does OCSP stapling we will get the callback (set in tls_init()) */
1911 # ifdef EXPERIMENTAL_DANE
1915 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1916 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1918 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1919 this means we avoid the OCSP request, we wasted the setup
1920 cost in tls_init(). */
1921 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1922 NULL, host->name, host->address, NULL) == OK;
1923 request_ocsp = require_ocsp ? TRUE
1924 : verify_check_this_host(&ob->hosts_request_ocsp,
1925 NULL, host->name, host->address, NULL) == OK;
1932 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1933 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1934 tls_out.ocsp = OCSP_NOT_RESP;
1938 #ifdef EXPERIMENTAL_EVENT
1939 client_static_cbinfo->event_action = tb->event_action;
1942 /* There doesn't seem to be a built-in timeout on connection. */
1944 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1945 sigalrm_seen = FALSE;
1946 alarm(ob->command_timeout);
1947 rc = SSL_connect(client_ssl);
1950 #ifdef EXPERIMENTAL_DANE
1952 DANESSL_cleanup(client_ssl);
1956 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1958 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1960 /* Beware anonymous ciphers which lead to server_cert being NULL */
1961 /*XXX server_cert is never freed... use X509_free() */
1962 server_cert = SSL_get_peer_certificate (client_ssl);
1965 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1966 CS txt, sizeof(txt));
1967 tls_out.peerdn = txt; /*XXX a static buffer... */
1970 tls_out.peerdn = NULL;
1972 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1973 tls_out.cipher = cipherbuf;
1975 /* Record the certificate we presented */
1977 X509 * crt = SSL_get_certificate(client_ssl);
1978 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1981 tls_out.active = fd;
1989 /*************************************************
1990 * TLS version of getc *
1991 *************************************************/
1993 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1994 it refills the buffer via the SSL reading function.
1997 Returns: the next character or EOF
1999 Only used by the server-side TLS.
2005 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2010 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2011 ssl_xfer_buffer, ssl_xfer_buffer_size);
2013 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2014 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2015 error = SSL_get_error(server_ssl, inbytes);
2018 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2019 closed down, not that the socket itself has been closed down. Revert to
2020 non-SSL handling. */
2022 if (error == SSL_ERROR_ZERO_RETURN)
2024 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2026 receive_getc = smtp_getc;
2027 receive_ungetc = smtp_ungetc;
2028 receive_feof = smtp_feof;
2029 receive_ferror = smtp_ferror;
2030 receive_smtp_buffered = smtp_buffered;
2032 SSL_free(server_ssl);
2036 tls_in.cipher = NULL;
2037 tls_in.peerdn = NULL;
2043 /* Handle genuine errors */
2045 else if (error == SSL_ERROR_SSL)
2047 ERR_error_string(ERR_get_error(), ssl_errstring);
2048 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2053 else if (error != SSL_ERROR_NONE)
2055 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2060 #ifndef DISABLE_DKIM
2061 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2063 ssl_xfer_buffer_hwm = inbytes;
2064 ssl_xfer_buffer_lwm = 0;
2067 /* Something in the buffer; return next uschar */
2069 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2074 /*************************************************
2075 * Read bytes from TLS channel *
2076 *************************************************/
2083 Returns: the number of bytes read
2084 -1 after a failed read
2086 Only used by the client-side TLS.
2090 tls_read(BOOL is_server, uschar *buff, size_t len)
2092 SSL *ssl = is_server ? server_ssl : client_ssl;
2096 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2097 buff, (unsigned int)len);
2099 inbytes = SSL_read(ssl, CS buff, len);
2100 error = SSL_get_error(ssl, inbytes);
2102 if (error == SSL_ERROR_ZERO_RETURN)
2104 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2107 else if (error != SSL_ERROR_NONE)
2119 /*************************************************
2120 * Write bytes down TLS channel *
2121 *************************************************/
2125 is_server channel specifier
2129 Returns: the number of bytes after a successful write,
2130 -1 after a failed write
2132 Used by both server-side and client-side TLS.
2136 tls_write(BOOL is_server, const uschar *buff, size_t len)
2141 SSL *ssl = is_server ? server_ssl : client_ssl;
2143 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2146 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2147 outbytes = SSL_write(ssl, CS buff, left);
2148 error = SSL_get_error(ssl, outbytes);
2149 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2153 ERR_error_string(ERR_get_error(), ssl_errstring);
2154 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2157 case SSL_ERROR_NONE:
2162 case SSL_ERROR_ZERO_RETURN:
2163 log_write(0, LOG_MAIN, "SSL channel closed on write");
2166 case SSL_ERROR_SYSCALL:
2167 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2168 sender_fullhost ? sender_fullhost : US"<unknown>",
2172 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2181 /*************************************************
2182 * Close down a TLS session *
2183 *************************************************/
2185 /* This is also called from within a delivery subprocess forked from the
2186 daemon, to shut down the TLS library, without actually doing a shutdown (which
2187 would tamper with the SSL session in the parent process).
2189 Arguments: TRUE if SSL_shutdown is to be called
2192 Used by both server-side and client-side TLS.
2196 tls_close(BOOL is_server, BOOL shutdown)
2198 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2199 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2201 if (*fdp < 0) return; /* TLS was not active */
2205 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2206 SSL_shutdown(*sslp);
2218 /*************************************************
2219 * Let tls_require_ciphers be checked at startup *
2220 *************************************************/
2222 /* The tls_require_ciphers option, if set, must be something which the
2225 Returns: NULL on success, or error message
2229 tls_validate_require_cipher(void)
2232 uschar *s, *expciphers, *err;
2234 /* this duplicates from tls_init(), we need a better "init just global
2235 state, for no specific purpose" singleton function of our own */
2237 SSL_load_error_strings();
2238 OpenSSL_add_ssl_algorithms();
2239 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2240 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2241 list of available digests. */
2242 EVP_add_digest(EVP_sha256());
2245 if (!(tls_require_ciphers && *tls_require_ciphers))
2248 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2249 return US"failed to expand tls_require_ciphers";
2251 if (!(expciphers && *expciphers))
2254 /* normalisation ripped from above */
2256 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2260 ctx = SSL_CTX_new(SSLv23_server_method());
2263 ERR_error_string(ERR_get_error(), ssl_errstring);
2264 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2268 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2270 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2272 ERR_error_string(ERR_get_error(), ssl_errstring);
2273 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2284 /*************************************************
2285 * Report the library versions. *
2286 *************************************************/
2288 /* There have historically been some issues with binary compatibility in
2289 OpenSSL libraries; if Exim (like many other applications) is built against
2290 one version of OpenSSL but the run-time linker picks up another version,
2291 it can result in serious failures, including crashing with a SIGSEGV. So
2292 report the version found by the compiler and the run-time version.
2294 Note: some OS vendors backport security fixes without changing the version
2295 number/string, and the version date remains unchanged. The _build_ date
2296 will change, so we can more usefully assist with version diagnosis by also
2297 reporting the build date.
2299 Arguments: a FILE* to print the results to
2304 tls_version_report(FILE *f)
2306 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2309 OPENSSL_VERSION_TEXT,
2310 SSLeay_version(SSLEAY_VERSION),
2311 SSLeay_version(SSLEAY_BUILT_ON));
2312 /* third line is 38 characters for the %s and the line is 73 chars long;
2313 the OpenSSL output includes a "built on: " prefix already. */
2319 /*************************************************
2320 * Random number generation *
2321 *************************************************/
2323 /* Pseudo-random number generation. The result is not expected to be
2324 cryptographically strong but not so weak that someone will shoot themselves
2325 in the foot using it as a nonce in input in some email header scheme or
2326 whatever weirdness they'll twist this into. The result should handle fork()
2327 and avoid repeating sequences. OpenSSL handles that for us.
2331 Returns a random number in range [0, max-1]
2335 vaguely_random_number(int max)
2339 static pid_t pidlast = 0;
2342 uschar smallbuf[sizeof(r)];
2348 if (pidnow != pidlast)
2350 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2351 is unique for each thread", this doesn't apparently apply across processes,
2352 so our own warning from vaguely_random_number_fallback() applies here too.
2353 Fix per PostgreSQL. */
2359 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2363 gettimeofday(&r.tv, NULL);
2366 RAND_seed((uschar *)(&r), sizeof(r));
2368 /* We're after pseudo-random, not random; if we still don't have enough data
2369 in the internal PRNG then our options are limited. We could sleep and hope
2370 for entropy to come along (prayer technique) but if the system is so depleted
2371 in the first place then something is likely to just keep taking it. Instead,
2372 we'll just take whatever little bit of pseudo-random we can still manage to
2375 needed_len = sizeof(r);
2376 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2377 asked for a number less than 10. */
2378 for (r = max, i = 0; r; ++i)
2384 /* We do not care if crypto-strong */
2385 i = RAND_pseudo_bytes(smallbuf, needed_len);
2389 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2390 return vaguely_random_number_fallback(max);
2394 for (p = smallbuf; needed_len; --needed_len, ++p)
2400 /* We don't particularly care about weighted results; if someone wants
2401 smooth distribution and cares enough then they should submit a patch then. */
2408 /*************************************************
2409 * OpenSSL option parse *
2410 *************************************************/
2412 /* Parse one option for tls_openssl_options_parse below
2415 name one option name
2416 value place to store a value for it
2417 Returns success or failure in parsing
2420 struct exim_openssl_option {
2424 /* We could use a macro to expand, but we need the ifdef and not all the
2425 options document which version they were introduced in. Policylet: include
2426 all options unless explicitly for DTLS, let the administrator choose which
2429 This list is current as of:
2431 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2433 static struct exim_openssl_option exim_openssl_options[] = {
2434 /* KEEP SORTED ALPHABETICALLY! */
2436 { US"all", SSL_OP_ALL },
2438 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2439 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2441 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2442 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2444 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2445 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2447 #ifdef SSL_OP_EPHEMERAL_RSA
2448 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2450 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2451 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2453 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2454 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2456 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2457 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2459 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2460 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2462 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2463 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2465 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2466 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2468 #ifdef SSL_OP_NO_COMPRESSION
2469 { US"no_compression", SSL_OP_NO_COMPRESSION },
2471 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2472 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2474 #ifdef SSL_OP_NO_SSLv2
2475 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2477 #ifdef SSL_OP_NO_SSLv3
2478 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2480 #ifdef SSL_OP_NO_TICKET
2481 { US"no_ticket", SSL_OP_NO_TICKET },
2483 #ifdef SSL_OP_NO_TLSv1
2484 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2486 #ifdef SSL_OP_NO_TLSv1_1
2487 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2488 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2489 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2491 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2494 #ifdef SSL_OP_NO_TLSv1_2
2495 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2497 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2498 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2500 #ifdef SSL_OP_SINGLE_DH_USE
2501 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2503 #ifdef SSL_OP_SINGLE_ECDH_USE
2504 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2506 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2507 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2509 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2510 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2512 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2513 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2515 #ifdef SSL_OP_TLS_D5_BUG
2516 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2518 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2519 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2522 static int exim_openssl_options_size =
2523 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2527 tls_openssl_one_option_parse(uschar *name, long *value)
2530 int last = exim_openssl_options_size;
2531 while (last > first)
2533 int middle = (first + last)/2;
2534 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2537 *value = exim_openssl_options[middle].value;
2551 /*************************************************
2552 * OpenSSL option parsing logic *
2553 *************************************************/
2555 /* OpenSSL has a number of compatibility options which an administrator might
2556 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2557 we look like log_selector.
2560 option_spec the administrator-supplied string of options
2561 results ptr to long storage for the options bitmap
2562 Returns success or failure
2566 tls_openssl_options_parse(uschar *option_spec, long *results)
2571 BOOL adding, item_parsed;
2574 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2575 * from default because it increases BEAST susceptibility. */
2576 #ifdef SSL_OP_NO_SSLv2
2577 result |= SSL_OP_NO_SSLv2;
2580 if (option_spec == NULL)
2586 for (s=option_spec; *s != '\0'; /**/)
2588 while (isspace(*s)) ++s;
2591 if (*s != '+' && *s != '-')
2593 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2594 "+ or - expected but found \"%s\"\n", s);
2597 adding = *s++ == '+';
2598 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2601 item_parsed = tls_openssl_one_option_parse(s, &item);
2604 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2607 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2608 adding ? "adding" : "removing", result, item, s);
2623 /* End of tls-openssl.c */