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_TPDA
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 uschar *conn_info = smtp_get_connection_info();
179 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
181 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
182 conn_info, prefix, msg);
187 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
188 host->name, host->address, prefix, msg);
195 /*************************************************
196 * Callback to generate RSA key *
197 *************************************************/
205 Returns: pointer to generated key
209 rsa_callback(SSL *s, int export, int keylength)
212 export = export; /* Shut picky compilers up */
213 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
214 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
217 ERR_error_string(ERR_get_error(), ssl_errstring);
218 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
230 x509_store_dump_cert_s_names(X509_STORE * store)
232 STACK_OF(X509_OBJECT) * roots= store->objs;
234 static uschar name[256];
236 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
238 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
239 if(tmp_obj->type == X509_LU_X509)
241 X509 * current_cert= tmp_obj->data.x509;
242 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
243 debug_printf(" %s\n", name);
251 /*************************************************
252 * Callback for verification *
253 *************************************************/
255 /* The SSL library does certificate verification if set up to do so. This
256 callback has the current yes/no state is in "state". If verification succeeded,
257 we set up the tls_peerdn string. If verification failed, what happens depends
258 on whether the client is required to present a verifiable certificate or not.
260 If verification is optional, we change the state to yes, but still log the
261 verification error. For some reason (it really would help to have proper
262 documentation of OpenSSL), this callback function then gets called again, this
263 time with state = 1. In fact, that's useful, because we can set up the peerdn
264 value, but we must take care not to set the private verified flag on the second
267 Note: this function is not called if the client fails to present a certificate
268 when asked. We get here only if a certificate has been received. Handling of
269 optional verification for this case is done when requesting SSL to verify, by
270 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
272 May be called multiple times for different issues with a certificate, even
273 for a given "depth" in the certificate chain.
276 state current yes/no state as 1/0
277 x509ctx certificate information.
278 client TRUE for client startup, FALSE for server startup
280 Returns: 1 if verified, 0 if not
284 verify_callback(int state, X509_STORE_CTX *x509ctx,
285 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
287 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
288 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
289 static uschar txt[256];
291 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
295 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
297 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
299 tlsp->certificate_verified = FALSE;
303 tlsp->peercert = X509_dup(cert);
304 return 0; /* reject */
306 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
307 "tls_try_verify_hosts)\n");
312 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
314 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
315 { /* client, wanting stapling */
316 /* Add the server cert's signing chain as the one
317 for the verification of the OCSP stapled information. */
319 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
324 #ifdef EXPERIMENTAL_TPDA
325 if (tlsp == &tls_out && client_static_cbinfo->event_action)
327 tlsp->peercert = X509_dup(cert);
328 if (tpda_raise_event(client_static_cbinfo->event_action,
329 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
331 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
332 "depth=%d cert=%s", depth, txt);
333 tlsp->certificate_verified = FALSE;
335 return 0; /* reject */
337 X509_free(tlsp->peercert);
338 tlsp->peercert = NULL;
344 #ifdef EXPERIMENTAL_CERTNAMES
345 uschar * verify_cert_hostnames;
349 tlsp->peercert = X509_dup(cert);
351 #ifdef EXPERIMENTAL_CERTNAMES
352 if ( tlsp == &tls_out
353 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
354 /* client, wanting hostname check */
356 # if OPENSSL_VERSION_NUMBER >= 0x010100000L || OPENSSL_VERSION_NUMBER >= 0x010002000L
357 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
358 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
362 uschar * list = verify_cert_hostnames;
365 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
366 if ((rc = X509_check_host(cert, name, 0,
367 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)))
371 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
378 log_write(0, LOG_MAIN,
379 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
380 return 0; /* reject */
384 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
386 log_write(0, LOG_MAIN,
387 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
388 return 0; /* reject */
391 #endif /*EXPERIMENTAL_CERTNAMES*/
393 #ifdef EXPERIMENTAL_TPDA
394 if (tlsp == &tls_out)
396 if (tpda_raise_event(client_static_cbinfo->event_action,
397 US"tls:cert", US"0") == DEFER)
399 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
400 "depth=0 cert=%s", txt);
401 tlsp->certificate_verified = FALSE;
403 return 0; /* reject */
408 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
409 *calledp ? "" : " authenticated", txt);
410 if (!*calledp) tlsp->certificate_verified = TRUE;
414 return 1; /* accept, at least for this level */
418 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
420 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
424 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
426 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
430 #ifdef EXPERIMENTAL_DANE
432 /* This gets called *by* the dane library verify callback, which interposes
436 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
438 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
439 static uschar txt[256];
441 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
443 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
444 tls_out.peerdn = txt;
445 tls_out.peercert = X509_dup(cert);
448 tls_out.dane_verified =
449 tls_out.certificate_verified = TRUE;
453 #endif /*EXPERIMENTAL_DANE*/
456 /*************************************************
457 * Information callback *
458 *************************************************/
460 /* The SSL library functions call this from time to time to indicate what they
461 are doing. We copy the string to the debugging output when TLS debugging has
473 info_callback(SSL *s, int where, int ret)
477 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
482 /*************************************************
483 * Initialize for DH *
484 *************************************************/
486 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
489 dhparam DH parameter file or fixed parameter identity string
490 host connected host, if client; NULL if server
492 Returns: TRUE if OK (nothing to set up, or setup worked)
496 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
503 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
506 if (!dhexpanded || !*dhexpanded)
507 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
508 else if (dhexpanded[0] == '/')
510 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
512 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
513 host, US strerror(errno));
519 if (Ustrcmp(dhexpanded, "none") == 0)
521 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
525 if (!(pem = std_dh_prime_named(dhexpanded)))
527 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
528 host, US strerror(errno));
531 bio = BIO_new_mem_buf(CS pem, -1);
534 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
537 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
542 /* Even if it is larger, we silently return success rather than cause things
543 * to fail out, so that a too-large DH will not knock out all TLS; it's a
544 * debatable choice. */
545 if ((8*DH_size(dh)) > tls_dh_max_bits)
548 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
549 8*DH_size(dh), tls_dh_max_bits);
553 SSL_CTX_set_tmp_dh(sctx, dh);
555 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
556 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
569 /*************************************************
570 * Load OCSP information into state *
571 *************************************************/
573 /* Called to load the server OCSP response from the given file into memory, once
574 caller has determined this is needed. Checks validity. Debugs a message
577 ASSUMES: single response, for single cert.
580 sctx the SSL_CTX* to update
581 cbinfo various parts of session state
582 expanded the filename putatively holding an OCSP response
587 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
591 OCSP_BASICRESP *basic_response;
592 OCSP_SINGLERESP *single_response;
593 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
595 unsigned long verify_flags;
596 int status, reason, i;
598 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
599 if (cbinfo->u_ocsp.server.response)
601 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
602 cbinfo->u_ocsp.server.response = NULL;
605 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
608 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
609 cbinfo->u_ocsp.server.file_expanded);
613 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
617 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
621 status = OCSP_response_status(resp);
622 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
624 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
625 OCSP_response_status_str(status), status);
629 basic_response = OCSP_response_get1_basic(resp);
633 debug_printf("OCSP response parse error: unable to extract basic response.\n");
637 store = SSL_CTX_get_cert_store(sctx);
638 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
640 /* May need to expose ability to adjust those flags?
641 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
642 OCSP_TRUSTOTHER OCSP_NOINTERN */
644 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
648 ERR_error_string(ERR_get_error(), ssl_errstring);
649 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
654 /* Here's the simplifying assumption: there's only one response, for the
655 one certificate we use, and nothing for anything else in a chain. If this
656 proves false, we need to extract a cert id from our issued cert
657 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
658 right cert in the stack and then calls OCSP_single_get0_status()).
660 I'm hoping to avoid reworking a bunch more of how we handle state here. */
661 single_response = OCSP_resp_get0(basic_response, 0);
662 if (!single_response)
665 debug_printf("Unable to get first response from OCSP basic response.\n");
669 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
670 if (status != V_OCSP_CERTSTATUS_GOOD)
672 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
673 OCSP_cert_status_str(status), status,
674 OCSP_crl_reason_str(reason), reason);
678 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
680 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
685 cbinfo->u_ocsp.server.response = resp;
689 if (running_in_test_harness)
691 extern char ** environ;
693 for (p = USS environ; *p != NULL; p++)
694 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
696 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
697 goto supply_response;
702 #endif /*!DISABLE_OCSP*/
707 /*************************************************
708 * Expand key and cert file specs *
709 *************************************************/
711 /* Called once during tls_init and possibly again during TLS setup, for a
712 new context, if Server Name Indication was used and tls_sni was seen in
713 the certificate string.
716 sctx the SSL_CTX* to update
717 cbinfo various parts of session state
719 Returns: OK/DEFER/FAIL
723 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
727 if (cbinfo->certificate == NULL)
730 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
731 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
732 Ustrstr(cbinfo->certificate, US"tls_out_sni")
734 reexpand_tls_files_for_sni = TRUE;
736 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
739 if (expanded != NULL)
741 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
742 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
743 return tls_error(string_sprintf(
744 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
748 if (cbinfo->privatekey != NULL &&
749 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
752 /* If expansion was forced to fail, key_expanded will be NULL. If the result
753 of the expansion is an empty string, ignore it also, and assume the private
754 key is in the same file as the certificate. */
756 if (expanded != NULL && *expanded != 0)
758 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
759 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
760 return tls_error(string_sprintf(
761 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
765 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
767 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
770 if (expanded != NULL && *expanded != 0)
772 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
773 if (cbinfo->u_ocsp.server.file_expanded &&
774 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
777 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
779 ocsp_load_response(sctx, cbinfo, expanded);
791 /*************************************************
792 * Callback to handle SNI *
793 *************************************************/
795 /* Called when acting as server during the TLS session setup if a Server Name
796 Indication extension was sent by the client.
798 API documentation is OpenSSL s_server.c implementation.
801 s SSL* of the current session
802 ad unknown (part of OpenSSL API) (unused)
803 arg Callback of "our" registered data
805 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
808 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
810 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
812 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
813 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
815 int old_pool = store_pool;
818 return SSL_TLSEXT_ERR_OK;
820 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
821 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
823 /* Make the extension value available for expansion */
824 store_pool = POOL_PERM;
825 tls_in.sni = string_copy(US servername);
826 store_pool = old_pool;
828 if (!reexpand_tls_files_for_sni)
829 return SSL_TLSEXT_ERR_OK;
831 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
832 not confident that memcpy wouldn't break some internal reference counting.
833 Especially since there's a references struct member, which would be off. */
835 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
837 ERR_error_string(ERR_get_error(), ssl_errstring);
838 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
839 return SSL_TLSEXT_ERR_NOACK;
842 /* Not sure how many of these are actually needed, since SSL object
843 already exists. Might even need this selfsame callback, for reneg? */
845 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
846 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
847 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
848 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
849 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
850 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
851 if (cbinfo->server_cipher_list)
852 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
854 if (cbinfo->u_ocsp.server.file)
856 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
857 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
861 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
862 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
864 /* do this after setup_certs, because this can require the certs for verifying
866 rc = tls_expand_session_files(server_sni, cbinfo);
867 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
869 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
870 return SSL_TLSEXT_ERR_NOACK;
872 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
873 SSL_set_SSL_CTX(s, server_sni);
875 return SSL_TLSEXT_ERR_OK;
877 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
884 /*************************************************
885 * Callback to handle OCSP Stapling *
886 *************************************************/
888 /* Called when acting as server during the TLS session setup if the client
889 requests OCSP information with a Certificate Status Request.
891 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
897 tls_server_stapling_cb(SSL *s, void *arg)
899 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
900 uschar *response_der;
901 int response_der_len;
904 debug_printf("Received TLS status request (OCSP stapling); %s response.",
905 cbinfo->u_ocsp.server.response ? "have" : "lack");
907 tls_in.ocsp = OCSP_NOT_RESP;
908 if (!cbinfo->u_ocsp.server.response)
909 return SSL_TLSEXT_ERR_NOACK;
912 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
914 if (response_der_len <= 0)
915 return SSL_TLSEXT_ERR_NOACK;
917 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
918 tls_in.ocsp = OCSP_VFIED;
919 return SSL_TLSEXT_ERR_OK;
924 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
926 BIO_printf(bp, "\t%s: ", str);
927 ASN1_GENERALIZEDTIME_print(bp, time);
932 tls_client_stapling_cb(SSL *s, void *arg)
934 tls_ext_ctx_cb * cbinfo = arg;
935 const unsigned char * p;
941 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
942 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
945 /* Expect this when we requested ocsp but got none */
946 if ( cbinfo->u_ocsp.client.verify_required
947 && log_extra_selector & LX_tls_cipher)
948 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
950 DEBUG(D_tls) debug_printf(" null\n");
951 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
954 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
956 tls_out.ocsp = OCSP_FAILED;
957 if (log_extra_selector & LX_tls_cipher)
958 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
960 DEBUG(D_tls) debug_printf(" parse error\n");
964 if(!(bs = OCSP_response_get1_basic(rsp)))
966 tls_out.ocsp = OCSP_FAILED;
967 if (log_extra_selector & LX_tls_cipher)
968 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
970 DEBUG(D_tls) debug_printf(" error parsing response\n");
971 OCSP_RESPONSE_free(rsp);
975 /* We'd check the nonce here if we'd put one in the request. */
976 /* However that would defeat cacheability on the server so we don't. */
978 /* This section of code reworked from OpenSSL apps source;
979 The OpenSSL Project retains copyright:
980 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
985 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
987 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
989 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
991 /* Use the chain that verified the server cert to verify the stapled info */
992 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
994 if ((i = OCSP_basic_verify(bs, NULL,
995 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
997 tls_out.ocsp = OCSP_FAILED;
998 if (log_extra_selector & LX_tls_cipher)
999 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1000 BIO_printf(bp, "OCSP response verify failure\n");
1001 ERR_print_errors(bp);
1002 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1006 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1009 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1010 OCSP_SINGLERESP * single;
1012 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1014 tls_out.ocsp = OCSP_FAILED;
1015 log_write(0, LOG_MAIN, "OCSP stapling "
1016 "with multiple responses not handled");
1017 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1020 single = OCSP_resp_get0(bs, 0);
1021 status = OCSP_single_get0_status(single, &reason, &rev,
1022 &thisupd, &nextupd);
1025 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1026 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1027 if (!OCSP_check_validity(thisupd, nextupd,
1028 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1030 tls_out.ocsp = OCSP_FAILED;
1031 DEBUG(D_tls) ERR_print_errors(bp);
1032 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1033 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1037 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1038 OCSP_cert_status_str(status));
1041 case V_OCSP_CERTSTATUS_GOOD:
1042 tls_out.ocsp = OCSP_VFIED;
1045 case V_OCSP_CERTSTATUS_REVOKED:
1046 tls_out.ocsp = OCSP_FAILED;
1047 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1048 reason != -1 ? "; reason: " : "",
1049 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1050 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1051 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1054 tls_out.ocsp = OCSP_FAILED;
1055 log_write(0, LOG_MAIN,
1056 "Server certificate status unknown, in OCSP stapling");
1057 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1065 OCSP_RESPONSE_free(rsp);
1068 #endif /*!DISABLE_OCSP*/
1071 /*************************************************
1072 * Initialize for TLS *
1073 *************************************************/
1075 /* Called from both server and client code, to do preliminary initialization
1076 of the library. We allocate and return a context structure.
1079 ctxp returned SSL context
1080 host connected host, if client; NULL if server
1081 dhparam DH parameter file
1082 certificate certificate file
1083 privatekey private key
1084 ocsp_file file of stapling info (server); flag for require ocsp (client)
1085 addr address if client; NULL if server (for some randomness)
1086 cbp place to put allocated callback context
1088 Returns: OK/DEFER/FAIL
1092 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1094 #ifndef DISABLE_OCSP
1097 address_item *addr, tls_ext_ctx_cb ** cbp)
1102 tls_ext_ctx_cb * cbinfo;
1104 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1105 cbinfo->certificate = certificate;
1106 cbinfo->privatekey = privatekey;
1107 #ifndef DISABLE_OCSP
1108 if ((cbinfo->is_server = host==NULL))
1110 cbinfo->u_ocsp.server.file = ocsp_file;
1111 cbinfo->u_ocsp.server.file_expanded = NULL;
1112 cbinfo->u_ocsp.server.response = NULL;
1115 cbinfo->u_ocsp.client.verify_store = NULL;
1117 cbinfo->dhparam = dhparam;
1118 cbinfo->server_cipher_list = NULL;
1119 cbinfo->host = host;
1120 #ifdef EXPERIMENTAL_TPDA
1121 cbinfo->event_action = NULL;
1124 SSL_load_error_strings(); /* basic set up */
1125 OpenSSL_add_ssl_algorithms();
1127 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1128 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1129 list of available digests. */
1130 EVP_add_digest(EVP_sha256());
1133 /* Create a context.
1134 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1135 negotiation in the different methods; as far as I can tell, the only
1136 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1137 when OpenSSL is built without SSLv2 support.
1138 By disabling with openssl_options, we can let admins re-enable with the
1141 *ctxp = SSL_CTX_new((host == NULL)?
1142 SSLv23_server_method() : SSLv23_client_method());
1144 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1146 /* It turns out that we need to seed the random number generator this early in
1147 order to get the full complement of ciphers to work. It took me roughly a day
1148 of work to discover this by experiment.
1150 On systems that have /dev/urandom, SSL may automatically seed itself from
1151 there. Otherwise, we have to make something up as best we can. Double check
1157 gettimeofday(&r.tv, NULL);
1160 RAND_seed((uschar *)(&r), sizeof(r));
1161 RAND_seed((uschar *)big_buffer, big_buffer_size);
1162 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1165 return tls_error(US"RAND_status", host,
1166 US"unable to seed random number generator");
1169 /* Set up the information callback, which outputs if debugging is at a suitable
1172 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1174 /* Automatically re-try reads/writes after renegotiation. */
1175 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1177 /* Apply administrator-supplied work-arounds.
1178 Historically we applied just one requested option,
1179 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1180 moved to an administrator-controlled list of options to specify and
1181 grandfathered in the first one as the default value for "openssl_options".
1183 No OpenSSL version number checks: the options we accept depend upon the
1184 availability of the option value macros from OpenSSL. */
1186 okay = tls_openssl_options_parse(openssl_options, &init_options);
1188 return tls_error(US"openssl_options parsing failed", host, NULL);
1192 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1193 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1194 return tls_error(string_sprintf(
1195 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1198 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1200 /* Initialize with DH parameters if supplied */
1202 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1204 /* Set up certificate and key (and perhaps OCSP info) */
1206 rc = tls_expand_session_files(*ctxp, cbinfo);
1207 if (rc != OK) return rc;
1209 /* If we need to handle SNI, do so */
1210 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1211 if (host == NULL) /* server */
1213 # ifndef DISABLE_OCSP
1214 /* We check u_ocsp.server.file, not server.response, because we care about if
1215 the option exists, not what the current expansion might be, as SNI might
1216 change the certificate and OCSP file in use between now and the time the
1217 callback is invoked. */
1218 if (cbinfo->u_ocsp.server.file)
1220 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1221 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1224 /* We always do this, so that $tls_sni is available even if not used in
1226 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1227 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1229 # ifndef DISABLE_OCSP
1231 if(ocsp_file) /* wanting stapling */
1233 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1235 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1238 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1239 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1244 #ifdef EXPERIMENTAL_CERTNAMES
1245 cbinfo->verify_cert_hostnames = NULL;
1248 /* Set up the RSA callback */
1250 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1252 /* Finally, set the timeout, and we are done */
1254 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1255 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1265 /*************************************************
1266 * Get name of cipher in use *
1267 *************************************************/
1270 Argument: pointer to an SSL structure for the connection
1271 buffer to use for answer
1273 pointer to number of bits for cipher
1278 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1280 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1281 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1282 the accessor functions use const in the prototype. */
1283 const SSL_CIPHER *c;
1286 ver = (const uschar *)SSL_get_version(ssl);
1288 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1289 SSL_CIPHER_get_bits(c, bits);
1291 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1292 SSL_CIPHER_get_name(c), *bits);
1294 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1301 /*************************************************
1302 * Set up for verifying certificates *
1303 *************************************************/
1305 /* Called by both client and server startup
1308 sctx SSL_CTX* to initialise
1309 certs certs file or NULL
1310 crl CRL file or NULL
1311 host NULL in a server; the remote host in a client
1312 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1313 otherwise passed as FALSE
1314 cert_vfy_cb Callback function for certificate verification
1316 Returns: OK/DEFER/FAIL
1320 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1321 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1323 uschar *expcerts, *expcrl;
1325 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1328 if (expcerts != NULL && *expcerts != '\0')
1330 struct stat statbuf;
1331 if (!SSL_CTX_set_default_verify_paths(sctx))
1332 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1334 if (Ustat(expcerts, &statbuf) < 0)
1336 log_write(0, LOG_MAIN|LOG_PANIC,
1337 "failed to stat %s for certificates", expcerts);
1343 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1344 { file = NULL; dir = expcerts; }
1346 { file = expcerts; dir = NULL; }
1348 /* If a certificate file is empty, the next function fails with an
1349 unhelpful error message. If we skip it, we get the correct behaviour (no
1350 certificates are recognized, but the error message is still misleading (it
1351 says no certificate was supplied.) But this is better. */
1353 if ((file == NULL || statbuf.st_size > 0) &&
1354 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1355 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1359 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
1363 /* Handle a certificate revocation list. */
1365 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1367 /* This bit of code is now the version supplied by Lars Mainka. (I have
1368 * merely reformatted it into the Exim code style.)
1370 * "From here I changed the code to add support for multiple crl's
1371 * in pem format in one file or to support hashed directory entries in
1372 * pem format instead of a file. This method now uses the library function
1373 * X509_STORE_load_locations to add the CRL location to the SSL context.
1374 * OpenSSL will then handle the verify against CA certs and CRLs by
1375 * itself in the verify callback." */
1377 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1378 if (expcrl != NULL && *expcrl != 0)
1380 struct stat statbufcrl;
1381 if (Ustat(expcrl, &statbufcrl) < 0)
1383 log_write(0, LOG_MAIN|LOG_PANIC,
1384 "failed to stat %s for certificates revocation lists", expcrl);
1389 /* is it a file or directory? */
1391 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1392 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1396 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1402 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1404 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1405 return tls_error(US"X509_STORE_load_locations", host, NULL);
1407 /* setting the flags to check against the complete crl chain */
1409 X509_STORE_set_flags(cvstore,
1410 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1414 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1416 /* If verification is optional, don't fail if no certificate */
1418 SSL_CTX_set_verify(sctx,
1419 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1428 /*************************************************
1429 * Start a TLS session in a server *
1430 *************************************************/
1432 /* This is called when Exim is running as a server, after having received
1433 the STARTTLS command. It must respond to that command, and then negotiate
1437 require_ciphers allowed ciphers
1439 Returns: OK on success
1440 DEFER for errors before the start of the negotiation
1441 FAIL for errors during the negotation; the server can't
1446 tls_server_start(const uschar *require_ciphers)
1450 tls_ext_ctx_cb *cbinfo;
1451 static uschar cipherbuf[256];
1453 /* Check for previous activation */
1455 if (tls_in.active >= 0)
1457 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1458 smtp_printf("554 Already in TLS\r\n");
1462 /* Initialize the SSL library. If it fails, it will already have logged
1465 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1466 #ifndef DISABLE_OCSP
1469 NULL, &server_static_cbinfo);
1470 if (rc != OK) return rc;
1471 cbinfo = server_static_cbinfo;
1473 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1476 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1477 were historically separated by underscores. So that I can use either form in my
1478 tests, and also for general convenience, we turn underscores into hyphens here.
1481 if (expciphers != NULL)
1483 uschar *s = expciphers;
1484 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1485 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1486 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1487 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1488 cbinfo->server_cipher_list = expciphers;
1491 /* If this is a host for which certificate verification is mandatory or
1492 optional, set up appropriately. */
1494 tls_in.certificate_verified = FALSE;
1495 #ifdef EXPERIMENTAL_DANE
1496 tls_in.dane_verified = FALSE;
1498 server_verify_callback_called = FALSE;
1500 if (verify_check_host(&tls_verify_hosts) == OK)
1502 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1503 FALSE, verify_callback_server);
1504 if (rc != OK) return rc;
1505 server_verify_optional = FALSE;
1507 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1509 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1510 TRUE, verify_callback_server);
1511 if (rc != OK) return rc;
1512 server_verify_optional = TRUE;
1515 /* Prepare for new connection */
1517 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1519 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1521 * With the SSL_clear(), we get strange interoperability bugs with
1522 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1523 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1525 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1526 * session shutdown. In this case, we have a brand new object and there's no
1527 * obvious reason to immediately clear it. I'm guessing that this was
1528 * originally added because of incomplete initialisation which the clear fixed,
1529 * in some historic release.
1532 /* Set context and tell client to go ahead, except in the case of TLS startup
1533 on connection, where outputting anything now upsets the clients and tends to
1534 make them disconnect. We need to have an explicit fflush() here, to force out
1535 the response. Other smtp_printf() calls do not need it, because in non-TLS
1536 mode, the fflush() happens when smtp_getc() is called. */
1538 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1539 if (!tls_in.on_connect)
1541 smtp_printf("220 TLS go ahead\r\n");
1545 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1546 that the OpenSSL library doesn't. */
1548 SSL_set_wfd(server_ssl, fileno(smtp_out));
1549 SSL_set_rfd(server_ssl, fileno(smtp_in));
1550 SSL_set_accept_state(server_ssl);
1552 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1554 sigalrm_seen = FALSE;
1555 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1556 rc = SSL_accept(server_ssl);
1561 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1562 if (ERR_get_error() == 0)
1563 log_write(0, LOG_MAIN,
1564 "TLS client disconnected cleanly (rejected our certificate?)");
1568 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1570 /* TLS has been set up. Adjust the input functions to read via TLS,
1571 and initialize things. */
1573 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1574 tls_in.cipher = cipherbuf;
1579 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1580 debug_printf("Shared ciphers: %s\n", buf);
1583 /* Record the certificate we presented */
1585 X509 * crt = SSL_get_certificate(server_ssl);
1586 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1589 /* Only used by the server-side tls (tls_in), including tls_getc.
1590 Client-side (tls_out) reads (seem to?) go via
1591 smtp_read_response()/ip_recv().
1592 Hence no need to duplicate for _in and _out.
1594 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1595 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1596 ssl_xfer_eof = ssl_xfer_error = 0;
1598 receive_getc = tls_getc;
1599 receive_ungetc = tls_ungetc;
1600 receive_feof = tls_feof;
1601 receive_ferror = tls_ferror;
1602 receive_smtp_buffered = tls_smtp_buffered;
1604 tls_in.active = fileno(smtp_out);
1612 tls_client_basic_ctx_init(SSL_CTX * ctx,
1613 host_item * host, smtp_transport_options_block * ob
1614 #ifdef EXPERIMENTAL_CERTNAMES
1615 , tls_ext_ctx_cb * cbinfo
1620 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1621 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1622 the specified host patterns if one of them is defined */
1624 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1625 (verify_check_host(&ob->tls_verify_hosts) == OK))
1627 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1628 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1630 client_verify_optional = FALSE;
1632 #ifdef EXPERIMENTAL_CERTNAMES
1633 if (ob->tls_verify_cert_hostnames)
1635 if (!expand_check(ob->tls_verify_cert_hostnames,
1636 US"tls_verify_cert_hostnames",
1637 &cbinfo->verify_cert_hostnames))
1639 if (cbinfo->verify_cert_hostnames)
1640 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1641 cbinfo->verify_cert_hostnames);
1645 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1647 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1648 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1650 client_verify_optional = TRUE;
1657 #ifdef EXPERIMENTAL_DANE
1659 tlsa_lookup(host_item * host, dns_answer * dnsa,
1660 BOOL dane_required, BOOL * dane)
1662 /* move this out to host.c given the similarity to dns_lookup() ? */
1664 uschar * fullname = buffer;
1666 /* TLSA lookup string */
1667 (void)sprintf(CS buffer, "_%d._tcp.%.256s", host->port, host->name);
1669 switch (dns_lookup(dnsa, buffer, T_TLSA, &fullname))
1672 return DEFER; /* just defer this TLS'd conn */
1678 log_write(0, LOG_MAIN, "DANE error: TLSA lookup failed");
1684 if (!dns_is_secure(dnsa))
1686 log_write(0, LOG_MAIN, "DANE error: TLSA lookup not DNSSEC");
1697 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1701 const char * hostnames[2] = { CS host->name, NULL };
1704 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1705 return tls_error(US"hostnames load", host, NULL);
1707 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1709 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1710 ) if (rr->type == T_TLSA)
1712 uschar * p = rr->data;
1713 uint8_t usage, selector, mtype;
1714 const char * mdname;
1724 log_write(0, LOG_MAIN,
1725 "DANE error: TLSA record w/bad mtype 0x%x", mtype);
1727 case 0: mdname = NULL; break;
1728 case 1: mdname = "sha256"; break;
1729 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 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)
1765 Returns: OK on success
1766 FAIL otherwise - note that tls_error() will not give DEFER
1767 because this is not a server
1771 tls_client_start(int fd, host_item *host, address_item *addr,
1772 transport_instance *tb)
1774 smtp_transport_options_block * ob =
1775 (smtp_transport_options_block *)tb->options_block;
1776 static uschar txt[256];
1777 uschar * expciphers;
1780 static uschar cipherbuf[256];
1782 #ifndef DISABLE_OCSP
1783 BOOL request_ocsp = FALSE;
1784 BOOL require_ocsp = FALSE;
1786 #ifdef EXPERIMENTAL_DANE
1787 dns_answer tlsa_dnsa;
1792 #ifdef EXPERIMENTAL_DANE
1793 tls_out.dane_verified = FALSE;
1794 tls_out.tlsa_usage = 0;
1795 dane_required = verify_check_this_host(&ob->hosts_require_dane, NULL,
1796 host->name, host->address, NULL) == OK;
1798 if (host->dnssec == DS_YES)
1801 || verify_check_this_host(&ob->hosts_try_dane, NULL,
1802 host->name, host->address, NULL) == OK
1804 if ((rc = tlsa_lookup(host, &tlsa_dnsa, dane_required, &dane)) != OK)
1807 else if (dane_required)
1809 /*XXX a shame we only find this after making tcp & smtp connection */
1810 /* move the test earlier? */
1811 log_write(0, LOG_MAIN, "DANE error: previous lookup not DNSSEC");
1816 #ifndef DISABLE_OCSP
1818 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1819 NULL, host->name, host->address, NULL) == OK))
1820 request_ocsp = TRUE;
1823 # ifdef EXPERIMENTAL_DANE
1825 && ob->hosts_request_ocsp[0] == '*'
1826 && ob->hosts_request_ocsp[1] == '\0'
1829 /* Unchanged from default. Use a safer one under DANE */
1830 request_ocsp = TRUE;
1831 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1832 " {= {4}{$tls_out_tlsa_usage}} } "
1837 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1838 NULL, host->name, host->address, NULL) == OK;
1843 rc = tls_init(&client_ctx, host, NULL,
1844 ob->tls_certificate, ob->tls_privatekey,
1845 #ifndef DISABLE_OCSP
1846 (void *)(long)request_ocsp,
1848 addr, &client_static_cbinfo);
1849 if (rc != OK) return rc;
1851 tls_out.certificate_verified = FALSE;
1852 client_verify_callback_called = FALSE;
1854 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1858 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1859 are separated by underscores. So that I can use either form in my tests, and
1860 also for general convenience, we turn underscores into hyphens here. */
1862 if (expciphers != NULL)
1864 uschar *s = expciphers;
1865 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1866 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1867 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1868 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1871 #ifdef EXPERIMENTAL_DANE
1874 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1876 if (!DANESSL_library_init())
1877 return tls_error(US"library init", host, NULL);
1878 if (DANESSL_CTX_init(client_ctx) <= 0)
1879 return tls_error(US"context init", host, NULL);
1885 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1886 #ifdef EXPERIMENTAL_CERTNAMES
1887 , client_static_cbinfo
1892 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1893 return tls_error(US"SSL_new", host, NULL);
1894 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1895 SSL_set_fd(client_ssl, fd);
1896 SSL_set_connect_state(client_ssl);
1900 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1902 if (tls_out.sni == NULL)
1904 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1906 else if (!Ustrlen(tls_out.sni))
1910 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1911 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1912 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1915 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1921 #ifdef EXPERIMENTAL_DANE
1923 if ((rc = dane_tlsa_load(client_ssl, host, &tlsa_dnsa)) != OK)
1927 #ifndef DISABLE_OCSP
1928 /* Request certificate status at connection-time. If the server
1929 does OCSP stapling we will get the callback (set in tls_init()) */
1930 # ifdef EXPERIMENTAL_DANE
1934 if ( (s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")
1935 || (s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")
1937 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1938 this means we avoid the OCSP request, we wasted the setup
1939 cost in tls_init(). */
1940 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1941 NULL, host->name, host->address, NULL) == OK;
1942 request_ocsp = require_ocsp ? TRUE
1943 : verify_check_this_host(&ob->hosts_request_ocsp,
1944 NULL, host->name, host->address, NULL) == OK;
1951 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1952 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1953 tls_out.ocsp = OCSP_NOT_RESP;
1957 #ifdef EXPERIMENTAL_TPDA
1958 client_static_cbinfo->event_action = tb->tpda_event_action;
1961 /* There doesn't seem to be a built-in timeout on connection. */
1963 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1964 sigalrm_seen = FALSE;
1965 alarm(ob->command_timeout);
1966 rc = SSL_connect(client_ssl);
1969 #ifdef EXPERIMENTAL_DANE
1971 DANESSL_cleanup(client_ssl);
1975 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1977 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1979 /* Beware anonymous ciphers which lead to server_cert being NULL */
1980 /*XXX server_cert is never freed... use X509_free() */
1981 server_cert = SSL_get_peer_certificate (client_ssl);
1984 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1985 CS txt, sizeof(txt));
1986 tls_out.peerdn = txt; /*XXX a static buffer... */
1989 tls_out.peerdn = NULL;
1991 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1992 tls_out.cipher = cipherbuf;
1994 /* Record the certificate we presented */
1996 X509 * crt = SSL_get_certificate(client_ssl);
1997 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2000 tls_out.active = fd;
2008 /*************************************************
2009 * TLS version of getc *
2010 *************************************************/
2012 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2013 it refills the buffer via the SSL reading function.
2016 Returns: the next character or EOF
2018 Only used by the server-side TLS.
2024 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2029 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2030 ssl_xfer_buffer, ssl_xfer_buffer_size);
2032 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2033 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2034 error = SSL_get_error(server_ssl, inbytes);
2037 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2038 closed down, not that the socket itself has been closed down. Revert to
2039 non-SSL handling. */
2041 if (error == SSL_ERROR_ZERO_RETURN)
2043 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2045 receive_getc = smtp_getc;
2046 receive_ungetc = smtp_ungetc;
2047 receive_feof = smtp_feof;
2048 receive_ferror = smtp_ferror;
2049 receive_smtp_buffered = smtp_buffered;
2051 SSL_free(server_ssl);
2055 tls_in.cipher = NULL;
2056 tls_in.peerdn = NULL;
2062 /* Handle genuine errors */
2064 else if (error == SSL_ERROR_SSL)
2066 ERR_error_string(ERR_get_error(), ssl_errstring);
2067 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2072 else if (error != SSL_ERROR_NONE)
2074 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2079 #ifndef DISABLE_DKIM
2080 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2082 ssl_xfer_buffer_hwm = inbytes;
2083 ssl_xfer_buffer_lwm = 0;
2086 /* Something in the buffer; return next uschar */
2088 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2093 /*************************************************
2094 * Read bytes from TLS channel *
2095 *************************************************/
2102 Returns: the number of bytes read
2103 -1 after a failed read
2105 Only used by the client-side TLS.
2109 tls_read(BOOL is_server, uschar *buff, size_t len)
2111 SSL *ssl = is_server ? server_ssl : client_ssl;
2115 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2116 buff, (unsigned int)len);
2118 inbytes = SSL_read(ssl, CS buff, len);
2119 error = SSL_get_error(ssl, inbytes);
2121 if (error == SSL_ERROR_ZERO_RETURN)
2123 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2126 else if (error != SSL_ERROR_NONE)
2138 /*************************************************
2139 * Write bytes down TLS channel *
2140 *************************************************/
2144 is_server channel specifier
2148 Returns: the number of bytes after a successful write,
2149 -1 after a failed write
2151 Used by both server-side and client-side TLS.
2155 tls_write(BOOL is_server, const uschar *buff, size_t len)
2160 SSL *ssl = is_server ? server_ssl : client_ssl;
2162 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2165 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2166 outbytes = SSL_write(ssl, CS buff, left);
2167 error = SSL_get_error(ssl, outbytes);
2168 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2172 ERR_error_string(ERR_get_error(), ssl_errstring);
2173 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2176 case SSL_ERROR_NONE:
2181 case SSL_ERROR_ZERO_RETURN:
2182 log_write(0, LOG_MAIN, "SSL channel closed on write");
2185 case SSL_ERROR_SYSCALL:
2186 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2187 sender_fullhost ? sender_fullhost : US"<unknown>",
2191 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2200 /*************************************************
2201 * Close down a TLS session *
2202 *************************************************/
2204 /* This is also called from within a delivery subprocess forked from the
2205 daemon, to shut down the TLS library, without actually doing a shutdown (which
2206 would tamper with the SSL session in the parent process).
2208 Arguments: TRUE if SSL_shutdown is to be called
2211 Used by both server-side and client-side TLS.
2215 tls_close(BOOL is_server, BOOL shutdown)
2217 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2218 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2220 if (*fdp < 0) return; /* TLS was not active */
2224 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2225 SSL_shutdown(*sslp);
2237 /*************************************************
2238 * Let tls_require_ciphers be checked at startup *
2239 *************************************************/
2241 /* The tls_require_ciphers option, if set, must be something which the
2244 Returns: NULL on success, or error message
2248 tls_validate_require_cipher(void)
2251 uschar *s, *expciphers, *err;
2253 /* this duplicates from tls_init(), we need a better "init just global
2254 state, for no specific purpose" singleton function of our own */
2256 SSL_load_error_strings();
2257 OpenSSL_add_ssl_algorithms();
2258 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2259 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2260 list of available digests. */
2261 EVP_add_digest(EVP_sha256());
2264 if (!(tls_require_ciphers && *tls_require_ciphers))
2267 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2268 return US"failed to expand tls_require_ciphers";
2270 if (!(expciphers && *expciphers))
2273 /* normalisation ripped from above */
2275 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2279 ctx = SSL_CTX_new(SSLv23_server_method());
2282 ERR_error_string(ERR_get_error(), ssl_errstring);
2283 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2287 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2289 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2291 ERR_error_string(ERR_get_error(), ssl_errstring);
2292 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2303 /*************************************************
2304 * Report the library versions. *
2305 *************************************************/
2307 /* There have historically been some issues with binary compatibility in
2308 OpenSSL libraries; if Exim (like many other applications) is built against
2309 one version of OpenSSL but the run-time linker picks up another version,
2310 it can result in serious failures, including crashing with a SIGSEGV. So
2311 report the version found by the compiler and the run-time version.
2313 Note: some OS vendors backport security fixes without changing the version
2314 number/string, and the version date remains unchanged. The _build_ date
2315 will change, so we can more usefully assist with version diagnosis by also
2316 reporting the build date.
2318 Arguments: a FILE* to print the results to
2323 tls_version_report(FILE *f)
2325 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2328 OPENSSL_VERSION_TEXT,
2329 SSLeay_version(SSLEAY_VERSION),
2330 SSLeay_version(SSLEAY_BUILT_ON));
2331 /* third line is 38 characters for the %s and the line is 73 chars long;
2332 the OpenSSL output includes a "built on: " prefix already. */
2338 /*************************************************
2339 * Random number generation *
2340 *************************************************/
2342 /* Pseudo-random number generation. The result is not expected to be
2343 cryptographically strong but not so weak that someone will shoot themselves
2344 in the foot using it as a nonce in input in some email header scheme or
2345 whatever weirdness they'll twist this into. The result should handle fork()
2346 and avoid repeating sequences. OpenSSL handles that for us.
2350 Returns a random number in range [0, max-1]
2354 vaguely_random_number(int max)
2358 static pid_t pidlast = 0;
2361 uschar smallbuf[sizeof(r)];
2367 if (pidnow != pidlast)
2369 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2370 is unique for each thread", this doesn't apparently apply across processes,
2371 so our own warning from vaguely_random_number_fallback() applies here too.
2372 Fix per PostgreSQL. */
2378 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2382 gettimeofday(&r.tv, NULL);
2385 RAND_seed((uschar *)(&r), sizeof(r));
2387 /* We're after pseudo-random, not random; if we still don't have enough data
2388 in the internal PRNG then our options are limited. We could sleep and hope
2389 for entropy to come along (prayer technique) but if the system is so depleted
2390 in the first place then something is likely to just keep taking it. Instead,
2391 we'll just take whatever little bit of pseudo-random we can still manage to
2394 needed_len = sizeof(r);
2395 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2396 asked for a number less than 10. */
2397 for (r = max, i = 0; r; ++i)
2403 /* We do not care if crypto-strong */
2404 i = RAND_pseudo_bytes(smallbuf, needed_len);
2408 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2409 return vaguely_random_number_fallback(max);
2413 for (p = smallbuf; needed_len; --needed_len, ++p)
2419 /* We don't particularly care about weighted results; if someone wants
2420 smooth distribution and cares enough then they should submit a patch then. */
2427 /*************************************************
2428 * OpenSSL option parse *
2429 *************************************************/
2431 /* Parse one option for tls_openssl_options_parse below
2434 name one option name
2435 value place to store a value for it
2436 Returns success or failure in parsing
2439 struct exim_openssl_option {
2443 /* We could use a macro to expand, but we need the ifdef and not all the
2444 options document which version they were introduced in. Policylet: include
2445 all options unless explicitly for DTLS, let the administrator choose which
2448 This list is current as of:
2450 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2452 static struct exim_openssl_option exim_openssl_options[] = {
2453 /* KEEP SORTED ALPHABETICALLY! */
2455 { US"all", SSL_OP_ALL },
2457 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2458 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2460 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2461 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2463 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2464 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2466 #ifdef SSL_OP_EPHEMERAL_RSA
2467 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2469 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2470 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2472 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2473 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2475 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2476 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2478 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2479 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2481 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2482 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2484 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2485 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2487 #ifdef SSL_OP_NO_COMPRESSION
2488 { US"no_compression", SSL_OP_NO_COMPRESSION },
2490 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2491 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2493 #ifdef SSL_OP_NO_SSLv2
2494 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2496 #ifdef SSL_OP_NO_SSLv3
2497 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2499 #ifdef SSL_OP_NO_TICKET
2500 { US"no_ticket", SSL_OP_NO_TICKET },
2502 #ifdef SSL_OP_NO_TLSv1
2503 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2505 #ifdef SSL_OP_NO_TLSv1_1
2506 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2507 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2508 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2510 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2513 #ifdef SSL_OP_NO_TLSv1_2
2514 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2516 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2517 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2519 #ifdef SSL_OP_SINGLE_DH_USE
2520 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2522 #ifdef SSL_OP_SINGLE_ECDH_USE
2523 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2525 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2526 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2528 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2529 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2531 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2532 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2534 #ifdef SSL_OP_TLS_D5_BUG
2535 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2537 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2538 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2541 static int exim_openssl_options_size =
2542 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2546 tls_openssl_one_option_parse(uschar *name, long *value)
2549 int last = exim_openssl_options_size;
2550 while (last > first)
2552 int middle = (first + last)/2;
2553 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2556 *value = exim_openssl_options[middle].value;
2570 /*************************************************
2571 * OpenSSL option parsing logic *
2572 *************************************************/
2574 /* OpenSSL has a number of compatibility options which an administrator might
2575 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2576 we look like log_selector.
2579 option_spec the administrator-supplied string of options
2580 results ptr to long storage for the options bitmap
2581 Returns success or failure
2585 tls_openssl_options_parse(uschar *option_spec, long *results)
2590 BOOL adding, item_parsed;
2593 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2594 * from default because it increases BEAST susceptibility. */
2595 #ifdef SSL_OP_NO_SSLv2
2596 result |= SSL_OP_NO_SSLv2;
2599 if (option_spec == NULL)
2605 for (s=option_spec; *s != '\0'; /**/)
2607 while (isspace(*s)) ++s;
2610 if (*s != '+' && *s != '-')
2612 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2613 "+ or - expected but found \"%s\"\n", s);
2616 adding = *s++ == '+';
2617 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2620 item_parsed = tls_openssl_one_option_parse(s, &item);
2623 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2626 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2627 adding ? "adding" : "removing", result, item, s);
2642 /* End of tls-openssl.c */