1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
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>
25 #ifndef OPENSSL_NO_ECDH
26 # include <openssl/ec.h>
29 # include <openssl/ocsp.h>
37 # define EXIM_OCSP_SKEW_SECONDS (300L)
38 # define EXIM_OCSP_MAX_AGE (-1L)
41 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
42 # define EXIM_HAVE_OPENSSL_TLSEXT
44 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
45 # define EXIM_HAVE_RSA_GENKEY_EX
47 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
48 # define EXIM_HAVE_OCSP_RESP_COUNT
50 # define EXIM_HAVE_EPHEM_RSA_KEX
51 # define EXIM_HAVE_RAND_PSEUDO
53 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
54 # define EXIM_HAVE_SHA256 /*MMMM*/
58 * X509_check_host provides sane certificate hostname checking, but was added
59 * to OpenSSL late, after other projects forked off the code-base. So in
60 * addition to guarding against the base version number, beware that LibreSSL
61 * does not (at this time) support this function.
63 * If LibreSSL gains a different API, perhaps via libtls, then we'll probably
64 * opt to disentangle and ask a LibreSSL user to provide glue for a third
65 * crypto provider for libtls instead of continuing to tie the OpenSSL glue
66 * into even twistier knots. If LibreSSL gains the same API, we can just
67 * change this guard and punt the issue for a while longer.
69 #ifndef LIBRESSL_VERSION_NUMBER
70 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
71 # define EXIM_HAVE_OPENSSL_CHECKHOST
72 # define EXIM_HAVE_OPENSSL_DH_BITS
73 # define EXIM_HAVE_OPENSSL_TLS_METHOD
75 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
76 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
77 # define EXIM_HAVE_OPENSSL_CHECKHOST
81 #if !defined(LIBRESSL_VERSION_NUMBER) \
82 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
83 # if !defined(OPENSSL_NO_ECDH)
84 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
85 # define EXIM_HAVE_ECDH /*MMMM*/
87 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
88 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
93 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
94 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
98 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
99 # include <openssl/x509v3.h>
102 /* Structure for collecting random data for seeding. */
104 typedef struct randstuff {
109 /* Local static variables */
111 static BOOL client_verify_callback_called = FALSE;
112 static BOOL server_verify_callback_called = FALSE;
113 static const uschar *sid_ctx = US"exim";
115 /* We have three different contexts to care about.
117 Simple case: client, `client_ctx`
118 As a client, we can be doing a callout or cut-through delivery while receiving
119 a message. So we have a client context, which should have options initialised
120 from the SMTP Transport. We may also concurrently want to make TLS connections
121 to utility daemons, so client-contexts are allocated and passed around in call
122 args rather than using a gobal.
125 There are two cases: with and without ServerNameIndication from the client.
126 Given TLS SNI, we can be using different keys, certs and various other
127 configuration settings, because they're re-expanded with $tls_sni set. This
128 allows vhosting with TLS. This SNI is sent in the handshake.
129 A client might not send SNI, so we need a fallback, and an initial setup too.
130 So as a server, we start out using `server_ctx`.
131 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
132 `server_sni` from `server_ctx` and then initialise settings by re-expanding
139 } exim_openssl_client_tls_ctx;
141 static SSL_CTX *server_ctx = NULL;
142 static SSL *server_ssl = NULL;
144 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
145 static SSL_CTX *server_sni = NULL;
148 static char ssl_errstring[256];
150 static int ssl_session_timeout = 200;
151 static BOOL client_verify_optional = FALSE;
152 static BOOL server_verify_optional = FALSE;
154 static BOOL reexpand_tls_files_for_sni = FALSE;
157 typedef struct tls_ext_ctx_cb {
162 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
166 uschar *file_expanded;
167 OCSP_RESPONSE *response;
170 X509_STORE *verify_store; /* non-null if status requested */
171 BOOL verify_required;
176 /* these are cached from first expand */
177 uschar *server_cipher_list;
178 /* only passed down to tls_error: */
180 const uschar * verify_cert_hostnames;
181 #ifndef DISABLE_EVENT
182 uschar * event_action;
186 /* should figure out a cleanup of API to handle state preserved per
187 implementation, for various reasons, which can be void * in the APIs.
188 For now, we hack around it. */
189 tls_ext_ctx_cb *client_static_cbinfo = NULL;
190 tls_ext_ctx_cb *server_static_cbinfo = NULL;
193 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
194 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
197 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
198 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
201 static int tls_server_stapling_cb(SSL *s, void *arg);
205 /*************************************************
207 *************************************************/
209 /* Called from lots of places when errors occur before actually starting to do
210 the TLS handshake, that is, while the session is still in clear. Always returns
211 DEFER for a server and FAIL for a client so that most calls can use "return
212 tls_error(...)" to do this processing and then give an appropriate return. A
213 single function is used for both server and client, because it is called from
214 some shared functions.
217 prefix text to include in the logged error
218 host NULL if setting up a server;
219 the connected host if setting up a client
220 msg error message or NULL if we should ask OpenSSL
221 errstr pointer to output error message
223 Returns: OK/DEFER/FAIL
227 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
231 ERR_error_string(ERR_get_error(), ssl_errstring);
232 msg = US ssl_errstring;
235 if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg);
236 return host ? FAIL : DEFER;
241 /*************************************************
242 * Callback to generate RSA key *
243 *************************************************/
247 s SSL connection (not used)
251 Returns: pointer to generated key
255 rsa_callback(SSL *s, int export, int keylength)
258 #ifdef EXIM_HAVE_RSA_GENKEY_EX
259 BIGNUM *bn = BN_new();
262 export = export; /* Shut picky compilers up */
263 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
265 #ifdef EXIM_HAVE_RSA_GENKEY_EX
266 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
267 || !(rsa_key = RSA_new())
268 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
271 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
275 ERR_error_string(ERR_get_error(), ssl_errstring);
276 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
288 x509_store_dump_cert_s_names(X509_STORE * store)
290 STACK_OF(X509_OBJECT) * roots= store->objs;
292 static uschar name[256];
294 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
296 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
297 if(tmp_obj->type == X509_LU_X509)
299 X509 * current_cert= tmp_obj->data.x509;
300 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
301 name[sizeof(name)-1] = '\0';
302 debug_printf(" %s\n", name);
310 #ifndef DISABLE_EVENT
312 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
313 BOOL *calledp, const BOOL *optionalp, const uschar * what)
319 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
322 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
323 old_cert = tlsp->peercert;
324 tlsp->peercert = X509_dup(cert);
325 /* NB we do not bother setting peerdn */
326 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
328 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
329 "depth=%d cert=%s: %s",
330 tlsp == &tls_out ? deliver_host_address : sender_host_address,
331 what, depth, dn, yield);
335 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
336 return 1; /* reject (leaving peercert set) */
338 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
339 "(host in tls_try_verify_hosts)\n");
341 X509_free(tlsp->peercert);
342 tlsp->peercert = old_cert;
348 /*************************************************
349 * Callback for verification *
350 *************************************************/
352 /* The SSL library does certificate verification if set up to do so. This
353 callback has the current yes/no state is in "state". If verification succeeded,
354 we set the certificate-verified flag. If verification failed, what happens
355 depends on whether the client is required to present a verifiable certificate
358 If verification is optional, we change the state to yes, but still log the
359 verification error. For some reason (it really would help to have proper
360 documentation of OpenSSL), this callback function then gets called again, this
361 time with state = 1. We must take care not to set the private verified flag on
362 the second time through.
364 Note: this function is not called if the client fails to present a certificate
365 when asked. We get here only if a certificate has been received. Handling of
366 optional verification for this case is done when requesting SSL to verify, by
367 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
369 May be called multiple times for different issues with a certificate, even
370 for a given "depth" in the certificate chain.
373 preverify_ok current yes/no state as 1/0
374 x509ctx certificate information.
375 tlsp per-direction (client vs. server) support data
376 calledp has-been-called flag
377 optionalp verification-is-optional flag
379 Returns: 0 if verification should fail, otherwise 1
383 verify_callback(int preverify_ok, X509_STORE_CTX *x509ctx,
384 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
386 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
387 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
390 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
391 dn[sizeof(dn)-1] = '\0';
393 if (preverify_ok == 0)
395 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
396 *verify_mode, sender_host_address)
398 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
399 tlsp == &tls_out ? deliver_host_address : sender_host_address,
401 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
406 tlsp->peercert = X509_dup(cert); /* record failing cert */
407 return 0; /* reject */
409 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
410 "tls_try_verify_hosts)\n");
415 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
417 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
418 { /* client, wanting stapling */
419 /* Add the server cert's signing chain as the one
420 for the verification of the OCSP stapled information. */
422 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
425 sk_X509_push(client_static_cbinfo->verify_stack, cert);
428 #ifndef DISABLE_EVENT
429 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
430 return 0; /* reject, with peercert set */
435 const uschar * verify_cert_hostnames;
437 if ( tlsp == &tls_out
438 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
439 /* client, wanting hostname check */
442 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
443 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
444 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
446 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
447 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
450 const uschar * list = verify_cert_hostnames;
453 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
454 if ((rc = X509_check_host(cert, CCS name, 0,
455 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
456 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
461 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
462 tlsp == &tls_out ? deliver_host_address : sender_host_address);
469 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
472 uschar * extra = verify_mode
473 ? string_sprintf(" (during %c-verify for [%s])",
474 *verify_mode, sender_host_address)
476 log_write(0, LOG_MAIN,
477 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
478 tlsp == &tls_out ? deliver_host_address : sender_host_address,
479 extra, dn, verify_cert_hostnames);
484 tlsp->peercert = X509_dup(cert); /* record failing cert */
485 return 0; /* reject */
487 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
488 "tls_try_verify_hosts)\n");
492 #ifndef DISABLE_EVENT
493 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
494 return 0; /* reject, with peercert set */
497 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
498 *calledp ? "" : " authenticated", dn);
499 if (!*calledp) tlsp->certificate_verified = TRUE;
503 return 1; /* accept, at least for this level */
507 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
509 return verify_callback(preverify_ok, x509ctx, &tls_out,
510 &client_verify_callback_called, &client_verify_optional);
514 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
516 return verify_callback(preverify_ok, x509ctx, &tls_in,
517 &server_verify_callback_called, &server_verify_optional);
523 /* This gets called *by* the dane library verify callback, which interposes
527 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
529 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
531 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
532 #ifndef DISABLE_EVENT
533 BOOL dummy_called, optional = FALSE;
536 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
537 dn[sizeof(dn)-1] = '\0';
539 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
540 preverify_ok ? "ok":"BAD", depth, dn);
542 #ifndef DISABLE_EVENT
543 if (verify_event(&tls_out, cert, depth, dn,
544 &dummy_called, &optional, US"DANE"))
545 return 0; /* reject, with peercert set */
548 if (preverify_ok == 1)
550 tls_out.dane_verified = tls_out.certificate_verified = TRUE;
552 if (client_static_cbinfo->u_ocsp.client.verify_store)
553 { /* client, wanting stapling */
554 /* Add the server cert's signing chain as the one
555 for the verification of the OCSP stapled information. */
557 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
560 sk_X509_push(client_static_cbinfo->verify_stack, cert);
566 int err = X509_STORE_CTX_get_error(x509ctx);
568 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
569 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
575 #endif /*SUPPORT_DANE*/
578 /*************************************************
579 * Information callback *
580 *************************************************/
582 /* The SSL library functions call this from time to time to indicate what they
583 are doing. We copy the string to the debugging output when TLS debugging has
595 info_callback(SSL *s, int where, int ret)
599 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
604 /*************************************************
605 * Initialize for DH *
606 *************************************************/
608 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
611 sctx The current SSL CTX (inbound or outbound)
612 dhparam DH parameter file or fixed parameter identity string
613 host connected host, if client; NULL if server
614 errstr error string pointer
616 Returns: TRUE if OK (nothing to set up, or setup worked)
620 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
628 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
631 if (!dhexpanded || !*dhexpanded)
632 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
633 else if (dhexpanded[0] == '/')
635 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
637 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
638 host, US strerror(errno), errstr);
644 if (Ustrcmp(dhexpanded, "none") == 0)
646 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
650 if (!(pem = std_dh_prime_named(dhexpanded)))
652 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
653 host, US strerror(errno), errstr);
656 bio = BIO_new_mem_buf(CS pem, -1);
659 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
662 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
667 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
668 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
669 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
670 * If someone wants to dance at the edge, then they can raise the limit or use
671 * current libraries. */
672 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
673 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
674 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
675 dh_bitsize = DH_bits(dh);
677 dh_bitsize = 8 * DH_size(dh);
680 /* Even if it is larger, we silently return success rather than cause things
681 * to fail out, so that a too-large DH will not knock out all TLS; it's a
682 * debatable choice. */
683 if (dh_bitsize > tls_dh_max_bits)
686 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
687 dh_bitsize, tls_dh_max_bits);
691 SSL_CTX_set_tmp_dh(sctx, dh);
693 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
694 dhexpanded ? dhexpanded : US"default", dh_bitsize);
706 /*************************************************
707 * Initialize for ECDH *
708 *************************************************/
710 /* Load parameters for ECDH encryption.
712 For now, we stick to NIST P-256 because: it's simple and easy to configure;
713 it avoids any patent issues that might bite redistributors; despite events in
714 the news and concerns over curve choices, we're not cryptographers, we're not
715 pretending to be, and this is "good enough" to be better than no support,
716 protecting against most adversaries. Given another year or two, there might
717 be sufficient clarity about a "right" way forward to let us make an informed
718 decision, instead of a knee-jerk reaction.
720 Longer-term, we should look at supporting both various named curves and
721 external files generated with "openssl ecparam", much as we do for init_dh().
722 We should also support "none" as a value, to explicitly avoid initialisation.
727 sctx The current SSL CTX (inbound or outbound)
728 host connected host, if client; NULL if server
729 errstr error string pointer
731 Returns: TRUE if OK (nothing to set up, or setup worked)
735 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
737 #ifdef OPENSSL_NO_ECDH
746 if (host) /* No ECDH setup for clients, only for servers */
749 # ifndef EXIM_HAVE_ECDH
751 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
755 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
757 if (!exp_curve || !*exp_curve)
760 /* "auto" needs to be handled carefully.
761 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
762 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
763 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
764 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
765 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
767 if (Ustrcmp(exp_curve, "auto") == 0)
769 #if OPENSSL_VERSION_NUMBER < 0x10002000L
770 DEBUG(D_tls) debug_printf(
771 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
772 exp_curve = US"prime256v1";
774 # if defined SSL_CTRL_SET_ECDH_AUTO
775 DEBUG(D_tls) debug_printf(
776 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
777 SSL_CTX_set_ecdh_auto(sctx, 1);
780 DEBUG(D_tls) debug_printf(
781 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
787 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
788 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
789 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
790 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
794 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
799 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
801 tls_error(US"Unable to create ec curve", host, NULL, errstr);
805 /* The "tmp" in the name here refers to setting a temporary key
806 not to the stability of the interface. */
808 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
809 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
811 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
816 # endif /*EXIM_HAVE_ECDH*/
817 #endif /*OPENSSL_NO_ECDH*/
824 /*************************************************
825 * Load OCSP information into state *
826 *************************************************/
827 /* Called to load the server OCSP response from the given file into memory, once
828 caller has determined this is needed. Checks validity. Debugs a message
831 ASSUMES: single response, for single cert.
834 sctx the SSL_CTX* to update
835 cbinfo various parts of session state
836 expanded the filename putatively holding an OCSP response
841 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
844 OCSP_RESPONSE * resp;
845 OCSP_BASICRESP * basic_response;
846 OCSP_SINGLERESP * single_response;
847 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
849 unsigned long verify_flags;
850 int status, reason, i;
852 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
853 if (cbinfo->u_ocsp.server.response)
855 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
856 cbinfo->u_ocsp.server.response = NULL;
859 if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
861 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
862 cbinfo->u_ocsp.server.file_expanded);
866 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
870 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
874 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
876 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
877 OCSP_response_status_str(status), status);
881 if (!(basic_response = OCSP_response_get1_basic(resp)))
884 debug_printf("OCSP response parse error: unable to extract basic response.\n");
888 sk = cbinfo->verify_stack;
889 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
891 /* May need to expose ability to adjust those flags?
892 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
893 OCSP_TRUSTOTHER OCSP_NOINTERN */
895 /* This does a full verify on the OCSP proof before we load it for serving
896 up; possibly overkill - just date-checks might be nice enough.
898 OCSP_basic_verify takes a "store" arg, but does not
899 use it for the chain verification, which is all we do
900 when OCSP_NOVERIFY is set. The content from the wire
901 "basic_response" and a cert-stack "sk" are all that is used.
903 We have a stack, loaded in setup_certs() if tls_verify_certificates
904 was a file (not a directory, or "system"). It is unfortunate we
905 cannot used the connection context store, as that would neatly
906 handle the "system" case too, but there seems to be no library
907 function for getting a stack from a store.
908 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
909 We do not free the stack since it could be needed a second time for
912 Separately we might try to replace using OCSP_basic_verify() - which seems to not
913 be a public interface into the OpenSSL library (there's no manual entry) -
914 But what with? We also use OCSP_basic_verify in the client stapling callback.
915 And there we NEED it; we must verify that status... unless the
916 library does it for us anyway? */
918 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
922 ERR_error_string(ERR_get_error(), ssl_errstring);
923 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
928 /* Here's the simplifying assumption: there's only one response, for the
929 one certificate we use, and nothing for anything else in a chain. If this
930 proves false, we need to extract a cert id from our issued cert
931 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
932 right cert in the stack and then calls OCSP_single_get0_status()).
934 I'm hoping to avoid reworking a bunch more of how we handle state here. */
936 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
939 debug_printf("Unable to get first response from OCSP basic response.\n");
943 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
944 if (status != V_OCSP_CERTSTATUS_GOOD)
946 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
947 OCSP_cert_status_str(status), status,
948 OCSP_crl_reason_str(reason), reason);
952 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
954 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
959 cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/
963 if (running_in_test_harness)
965 extern char ** environ;
967 if (environ) for (p = USS environ; *p; p++)
968 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
970 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
971 goto supply_response;
976 #endif /*!DISABLE_OCSP*/
981 /* Create and install a selfsigned certificate, for use in server mode */
984 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
992 where = US"allocating pkey";
993 if (!(pkey = EVP_PKEY_new()))
996 where = US"allocating cert";
997 if (!(x509 = X509_new()))
1000 where = US"generating pkey";
1001 if (!(rsa = rsa_callback(NULL, 0, 1024)))
1004 where = US"assigning pkey";
1005 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1008 X509_set_version(x509, 2); /* N+1 - version 3 */
1009 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1010 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1011 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1012 X509_set_pubkey(x509, pkey);
1014 name = X509_get_subject_name(x509);
1015 X509_NAME_add_entry_by_txt(name, "C",
1016 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1017 X509_NAME_add_entry_by_txt(name, "O",
1018 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1019 X509_NAME_add_entry_by_txt(name, "CN",
1020 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1021 X509_set_issuer_name(x509, name);
1023 where = US"signing cert";
1024 if (!X509_sign(x509, pkey, EVP_md5()))
1027 where = US"installing selfsign cert";
1028 if (!SSL_CTX_use_certificate(sctx, x509))
1031 where = US"installing selfsign key";
1032 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1038 (void) tls_error(where, NULL, NULL, errstr);
1039 if (x509) X509_free(x509);
1040 if (pkey) EVP_PKEY_free(pkey);
1048 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1051 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file);
1052 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1053 return tls_error(string_sprintf(
1054 "SSL_CTX_use_certificate_chain_file file=%s", file),
1055 cbinfo->host, NULL, errstr);
1060 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1063 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file);
1064 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1065 return tls_error(string_sprintf(
1066 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1071 /*************************************************
1072 * Expand key and cert file specs *
1073 *************************************************/
1075 /* Called once during tls_init and possibly again during TLS setup, for a
1076 new context, if Server Name Indication was used and tls_sni was seen in
1077 the certificate string.
1080 sctx the SSL_CTX* to update
1081 cbinfo various parts of session state
1082 errstr error string pointer
1084 Returns: OK/DEFER/FAIL
1088 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1093 if (!cbinfo->certificate)
1095 if (!cbinfo->is_server) /* client */
1098 if (tls_install_selfsign(sctx, errstr) != OK)
1105 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1106 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1107 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1109 reexpand_tls_files_for_sni = TRUE;
1111 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1115 if (cbinfo->is_server)
1117 const uschar * file_list = expanded;
1121 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1122 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1125 else /* would there ever be a need for multiple client certs? */
1126 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1129 if (cbinfo->privatekey != NULL &&
1130 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1133 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1134 of the expansion is an empty string, ignore it also, and assume the private
1135 key is in the same file as the certificate. */
1137 if (expanded && *expanded)
1138 if (cbinfo->is_server)
1140 const uschar * file_list = expanded;
1144 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1145 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1148 else /* would there ever be a need for multiple client certs? */
1149 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1153 #ifndef DISABLE_OCSP
1154 if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
1157 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
1160 if (expanded && *expanded)
1162 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
1163 if ( cbinfo->u_ocsp.server.file_expanded
1164 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
1166 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1169 ocsp_load_response(sctx, cbinfo, expanded);
1180 /*************************************************
1181 * Callback to handle SNI *
1182 *************************************************/
1184 /* Called when acting as server during the TLS session setup if a Server Name
1185 Indication extension was sent by the client.
1187 API documentation is OpenSSL s_server.c implementation.
1190 s SSL* of the current session
1191 ad unknown (part of OpenSSL API) (unused)
1192 arg Callback of "our" registered data
1194 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1197 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1199 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1201 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1202 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1204 int old_pool = store_pool;
1205 uschar * dummy_errstr;
1208 return SSL_TLSEXT_ERR_OK;
1210 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1211 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1213 /* Make the extension value available for expansion */
1214 store_pool = POOL_PERM;
1215 tls_in.sni = string_copy(US servername);
1216 store_pool = old_pool;
1218 if (!reexpand_tls_files_for_sni)
1219 return SSL_TLSEXT_ERR_OK;
1221 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1222 not confident that memcpy wouldn't break some internal reference counting.
1223 Especially since there's a references struct member, which would be off. */
1225 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1226 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1228 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1231 ERR_error_string(ERR_get_error(), ssl_errstring);
1232 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1233 return SSL_TLSEXT_ERR_NOACK;
1236 /* Not sure how many of these are actually needed, since SSL object
1237 already exists. Might even need this selfsame callback, for reneg? */
1239 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1240 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1241 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1242 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1243 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1244 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1246 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1247 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1249 return SSL_TLSEXT_ERR_NOACK;
1251 if (cbinfo->server_cipher_list)
1252 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
1253 #ifndef DISABLE_OCSP
1254 if (cbinfo->u_ocsp.server.file)
1256 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1257 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1261 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1262 verify_callback_server, &dummy_errstr)) != OK)
1263 return SSL_TLSEXT_ERR_NOACK;
1265 /* do this after setup_certs, because this can require the certs for verifying
1266 OCSP information. */
1267 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1268 return SSL_TLSEXT_ERR_NOACK;
1270 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1271 SSL_set_SSL_CTX(s, server_sni);
1273 return SSL_TLSEXT_ERR_OK;
1275 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1280 #ifndef DISABLE_OCSP
1282 /*************************************************
1283 * Callback to handle OCSP Stapling *
1284 *************************************************/
1286 /* Called when acting as server during the TLS session setup if the client
1287 requests OCSP information with a Certificate Status Request.
1289 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1295 tls_server_stapling_cb(SSL *s, void *arg)
1297 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1298 uschar *response_der; /*XXX blob */
1299 int response_der_len;
1301 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1302 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1303 buggy in current OpenSSL; it returns the last cert loaded always rather than
1304 the one actually presented. So we can't support a stack of OCSP proofs at
1308 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1309 cbinfo->u_ocsp.server.response ? "have" : "lack");
1311 tls_in.ocsp = OCSP_NOT_RESP;
1312 if (!cbinfo->u_ocsp.server.response)
1313 return SSL_TLSEXT_ERR_NOACK;
1315 response_der = NULL;
1316 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1318 if (response_der_len <= 0)
1319 return SSL_TLSEXT_ERR_NOACK;
1321 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1322 tls_in.ocsp = OCSP_VFIED;
1323 return SSL_TLSEXT_ERR_OK;
1328 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1330 BIO_printf(bp, "\t%s: ", str);
1331 ASN1_GENERALIZEDTIME_print(bp, time);
1336 tls_client_stapling_cb(SSL *s, void *arg)
1338 tls_ext_ctx_cb * cbinfo = arg;
1339 const unsigned char * p;
1341 OCSP_RESPONSE * rsp;
1342 OCSP_BASICRESP * bs;
1345 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1346 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1349 /* Expect this when we requested ocsp but got none */
1350 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1351 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1353 DEBUG(D_tls) debug_printf(" null\n");
1354 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1357 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1359 tls_out.ocsp = OCSP_FAILED;
1360 if (LOGGING(tls_cipher))
1361 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1363 DEBUG(D_tls) debug_printf(" parse error\n");
1367 if(!(bs = OCSP_response_get1_basic(rsp)))
1369 tls_out.ocsp = OCSP_FAILED;
1370 if (LOGGING(tls_cipher))
1371 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1373 DEBUG(D_tls) debug_printf(" error parsing response\n");
1374 OCSP_RESPONSE_free(rsp);
1378 /* We'd check the nonce here if we'd put one in the request. */
1379 /* However that would defeat cacheability on the server so we don't. */
1381 /* This section of code reworked from OpenSSL apps source;
1382 The OpenSSL Project retains copyright:
1383 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1388 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1390 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1392 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1394 /* Use the chain that verified the server cert to verify the stapled info */
1395 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1397 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1398 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1400 tls_out.ocsp = OCSP_FAILED;
1401 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1402 "Received TLS cert status response, itself unverifiable: %s",
1403 ERR_reason_error_string(ERR_peek_error()));
1404 BIO_printf(bp, "OCSP response verify failure\n");
1405 ERR_print_errors(bp);
1406 OCSP_RESPONSE_print(bp, rsp, 0);
1410 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1412 /*XXX So we have a good stapled OCSP status. How do we know
1413 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1414 OCSP_resp_find_status() which matches on a cert id, which presumably
1415 we should use. Making an id needs OCSP_cert_id_new(), which takes
1416 issuerName, issuerKey, serialNumber. Are they all in the cert?
1418 For now, carry on blindly accepting the resp. */
1421 OCSP_SINGLERESP * single;
1423 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1424 if (OCSP_resp_count(bs) != 1)
1426 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1427 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1430 tls_out.ocsp = OCSP_FAILED;
1431 log_write(0, LOG_MAIN, "OCSP stapling "
1432 "with multiple responses not handled");
1435 single = OCSP_resp_get0(bs, 0);
1436 status = OCSP_single_get0_status(single, &reason, &rev,
1437 &thisupd, &nextupd);
1440 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1441 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1442 if (!OCSP_check_validity(thisupd, nextupd,
1443 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1445 tls_out.ocsp = OCSP_FAILED;
1446 DEBUG(D_tls) ERR_print_errors(bp);
1447 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1451 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1452 OCSP_cert_status_str(status));
1455 case V_OCSP_CERTSTATUS_GOOD:
1456 tls_out.ocsp = OCSP_VFIED;
1459 case V_OCSP_CERTSTATUS_REVOKED:
1460 tls_out.ocsp = OCSP_FAILED;
1461 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1462 reason != -1 ? "; reason: " : "",
1463 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1464 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1467 tls_out.ocsp = OCSP_FAILED;
1468 log_write(0, LOG_MAIN,
1469 "Server certificate status unknown, in OCSP stapling");
1474 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1479 OCSP_RESPONSE_free(rsp);
1482 #endif /*!DISABLE_OCSP*/
1485 /*************************************************
1486 * Initialize for TLS *
1487 *************************************************/
1489 /* Called from both server and client code, to do preliminary initialization
1490 of the library. We allocate and return a context structure.
1493 ctxp returned SSL context
1494 host connected host, if client; NULL if server
1495 dhparam DH parameter file
1496 certificate certificate file
1497 privatekey private key
1498 ocsp_file file of stapling info (server); flag for require ocsp (client)
1499 addr address if client; NULL if server (for some randomness)
1500 cbp place to put allocated callback context
1501 errstr error string pointer
1503 Returns: OK/DEFER/FAIL
1507 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1509 #ifndef DISABLE_OCSP
1510 uschar *ocsp_file, /*XXX stack, in server*/
1512 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
1517 tls_ext_ctx_cb * cbinfo;
1519 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1520 cbinfo->certificate = certificate;
1521 cbinfo->privatekey = privatekey;
1522 cbinfo->is_server = host==NULL;
1523 #ifndef DISABLE_OCSP
1524 cbinfo->verify_stack = NULL;
1527 cbinfo->u_ocsp.server.file = ocsp_file;
1528 cbinfo->u_ocsp.server.file_expanded = NULL;
1529 cbinfo->u_ocsp.server.response = NULL;
1532 cbinfo->u_ocsp.client.verify_store = NULL;
1534 cbinfo->dhparam = dhparam;
1535 cbinfo->server_cipher_list = NULL;
1536 cbinfo->host = host;
1537 #ifndef DISABLE_EVENT
1538 cbinfo->event_action = NULL;
1541 SSL_load_error_strings(); /* basic set up */
1542 OpenSSL_add_ssl_algorithms();
1544 #ifdef EXIM_HAVE_SHA256
1545 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1546 list of available digests. */
1547 EVP_add_digest(EVP_sha256());
1550 /* Create a context.
1551 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1552 negotiation in the different methods; as far as I can tell, the only
1553 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1554 when OpenSSL is built without SSLv2 support.
1555 By disabling with openssl_options, we can let admins re-enable with the
1558 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1559 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1561 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1563 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1565 /* It turns out that we need to seed the random number generator this early in
1566 order to get the full complement of ciphers to work. It took me roughly a day
1567 of work to discover this by experiment.
1569 On systems that have /dev/urandom, SSL may automatically seed itself from
1570 there. Otherwise, we have to make something up as best we can. Double check
1576 gettimeofday(&r.tv, NULL);
1579 RAND_seed(US (&r), sizeof(r));
1580 RAND_seed(US big_buffer, big_buffer_size);
1581 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1584 return tls_error(US"RAND_status", host,
1585 US"unable to seed random number generator", errstr);
1588 /* Set up the information callback, which outputs if debugging is at a suitable
1591 DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1593 /* Automatically re-try reads/writes after renegotiation. */
1594 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1596 /* Apply administrator-supplied work-arounds.
1597 Historically we applied just one requested option,
1598 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1599 moved to an administrator-controlled list of options to specify and
1600 grandfathered in the first one as the default value for "openssl_options".
1602 No OpenSSL version number checks: the options we accept depend upon the
1603 availability of the option value macros from OpenSSL. */
1605 if (!tls_openssl_options_parse(openssl_options, &init_options))
1606 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1610 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1611 if (!(SSL_CTX_set_options(ctx, init_options)))
1612 return tls_error(string_sprintf(
1613 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
1616 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1618 /* We'd like to disable session cache unconditionally, but foolish Outlook
1619 Express clients then give up the first TLS connection and make a second one
1620 (which works). Only when there is an IMAP service on the same machine.
1621 Presumably OE is trying to use the cache for A on B. Leave it enabled for
1622 now, until we work out a decent way of presenting control to the config. It
1623 will never be used because we use a new context every time. */
1625 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
1628 /* Initialize with DH parameters if supplied */
1629 /* Initialize ECDH temp key parameter selection */
1631 if ( !init_dh(ctx, dhparam, host, errstr)
1632 || !init_ecdh(ctx, host, errstr)
1636 /* Set up certificate and key (and perhaps OCSP info) */
1638 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
1641 /* If we need to handle SNI or OCSP, do so */
1643 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1644 # ifndef DISABLE_OCSP
1645 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1647 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1652 if (!host) /* server */
1654 # ifndef DISABLE_OCSP
1655 /* We check u_ocsp.server.file, not server.response, because we care about if
1656 the option exists, not what the current expansion might be, as SNI might
1657 change the certificate and OCSP file in use between now and the time the
1658 callback is invoked. */
1659 if (cbinfo->u_ocsp.server.file)
1661 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
1662 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1665 /* We always do this, so that $tls_sni is available even if not used in
1667 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
1668 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
1670 # ifndef DISABLE_OCSP
1672 if(ocsp_file) /* wanting stapling */
1674 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1676 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1679 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
1680 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1685 cbinfo->verify_cert_hostnames = NULL;
1687 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1688 /* Set up the RSA callback */
1689 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
1692 /* Finally, set the timeout, and we are done */
1694 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
1695 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1706 /*************************************************
1707 * Get name of cipher in use *
1708 *************************************************/
1711 Argument: pointer to an SSL structure for the connection
1712 buffer to use for answer
1714 pointer to number of bits for cipher
1719 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1721 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
1722 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1723 the accessor functions use const in the prototype. */
1725 const uschar * ver = CUS SSL_get_version(ssl);
1726 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1728 SSL_CIPHER_get_bits(c, bits);
1730 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1731 SSL_CIPHER_get_name(c), *bits);
1733 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1738 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1740 /*XXX we might consider a list-of-certs variable for the cert chain.
1741 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1742 in list-handling functions, also consider the difference between the entire
1743 chain and the elements sent by the peer. */
1745 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1746 if (!tlsp->peercert)
1747 tlsp->peercert = SSL_get_peer_certificate(ssl);
1748 /* Beware anonymous ciphers which lead to server_cert being NULL */
1751 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1752 peerdn[bsize-1] = '\0';
1753 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1756 tlsp->peerdn = NULL;
1763 /*************************************************
1764 * Set up for verifying certificates *
1765 *************************************************/
1767 #ifndef DISABLE_OCSP
1768 /* Load certs from file, return TRUE on success */
1771 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1776 while (sk_X509_num(verify_stack) > 0)
1777 X509_free(sk_X509_pop(verify_stack));
1779 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1780 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1781 sk_X509_push(verify_stack, x);
1789 /* Called by both client and server startup; on the server possibly
1790 repeated after a Server Name Indication.
1793 sctx SSL_CTX* to initialise
1794 certs certs file or NULL
1795 crl CRL file or NULL
1796 host NULL in a server; the remote host in a client
1797 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1798 otherwise passed as FALSE
1799 cert_vfy_cb Callback function for certificate verification
1800 errstr error string pointer
1802 Returns: OK/DEFER/FAIL
1806 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1807 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
1809 uschar *expcerts, *expcrl;
1811 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
1813 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
1815 if (expcerts && *expcerts)
1817 /* Tell the library to use its compiled-in location for the system default
1818 CA bundle. Then add the ones specified in the config, if any. */
1820 if (!SSL_CTX_set_default_verify_paths(sctx))
1821 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
1823 if (Ustrcmp(expcerts, "system") != 0)
1825 struct stat statbuf;
1827 if (Ustat(expcerts, &statbuf) < 0)
1829 log_write(0, LOG_MAIN|LOG_PANIC,
1830 "failed to stat %s for certificates", expcerts);
1836 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1837 { file = NULL; dir = expcerts; }
1840 file = expcerts; dir = NULL;
1841 #ifndef DISABLE_OCSP
1842 /* In the server if we will be offering an OCSP proof, load chain from
1843 file for verifying the OCSP proof at load time. */
1846 && statbuf.st_size > 0
1847 && server_static_cbinfo->u_ocsp.server.file
1848 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
1851 log_write(0, LOG_MAIN|LOG_PANIC,
1852 "failed to load cert chain from %s", file);
1858 /* If a certificate file is empty, the next function fails with an
1859 unhelpful error message. If we skip it, we get the correct behaviour (no
1860 certificates are recognized, but the error message is still misleading (it
1861 says no certificate was supplied). But this is better. */
1863 if ( (!file || statbuf.st_size > 0)
1864 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1865 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
1867 /* Load the list of CAs for which we will accept certs, for sending
1868 to the client. This is only for the one-file tls_verify_certificates
1870 If a list isn't loaded into the server, but
1871 some verify locations are set, the server end appears to make
1872 a wildcard request for client certs.
1873 Meanwhile, the client library as default behaviour *ignores* the list
1874 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1875 Because of this, and that the dir variant is likely only used for
1876 the public-CA bundle (not for a private CA), not worth fixing.
1880 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1882 SSL_CTX_set_client_CA_list(sctx, names);
1883 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1884 sk_X509_NAME_num(names));
1889 /* Handle a certificate revocation list. */
1891 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1893 /* This bit of code is now the version supplied by Lars Mainka. (I have
1894 merely reformatted it into the Exim code style.)
1896 "From here I changed the code to add support for multiple crl's
1897 in pem format in one file or to support hashed directory entries in
1898 pem format instead of a file. This method now uses the library function
1899 X509_STORE_load_locations to add the CRL location to the SSL context.
1900 OpenSSL will then handle the verify against CA certs and CRLs by
1901 itself in the verify callback." */
1903 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
1904 if (expcrl && *expcrl)
1906 struct stat statbufcrl;
1907 if (Ustat(expcrl, &statbufcrl) < 0)
1909 log_write(0, LOG_MAIN|LOG_PANIC,
1910 "failed to stat %s for certificates revocation lists", expcrl);
1915 /* is it a file or directory? */
1917 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1918 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1922 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1928 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1930 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1931 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
1933 /* setting the flags to check against the complete crl chain */
1935 X509_STORE_set_flags(cvstore,
1936 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1940 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1942 /* If verification is optional, don't fail if no certificate */
1944 SSL_CTX_set_verify(sctx,
1945 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1954 /*************************************************
1955 * Start a TLS session in a server *
1956 *************************************************/
1958 /* This is called when Exim is running as a server, after having received
1959 the STARTTLS command. It must respond to that command, and then negotiate
1963 require_ciphers allowed ciphers
1964 errstr pointer to error message
1966 Returns: OK on success
1967 DEFER for errors before the start of the negotiation
1968 FAIL for errors during the negotiation; the server can't
1973 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
1976 uschar * expciphers;
1977 tls_ext_ctx_cb * cbinfo;
1978 static uschar peerdn[256];
1979 static uschar cipherbuf[256];
1981 /* Check for previous activation */
1983 if (tls_in.active.sock >= 0)
1985 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
1986 smtp_printf("554 Already in TLS\r\n", FALSE);
1990 /* Initialize the SSL library. If it fails, it will already have logged
1993 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1994 #ifndef DISABLE_OCSP
1995 tls_ocsp_file, /*XXX stack*/
1997 NULL, &server_static_cbinfo, errstr);
1998 if (rc != OK) return rc;
1999 cbinfo = server_static_cbinfo;
2001 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2004 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2005 were historically separated by underscores. So that I can use either form in my
2006 tests, and also for general convenience, we turn underscores into hyphens here.
2008 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2009 for TLS 1.3 . Since we do not call it at present we get the default list:
2010 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2015 uschar * s = expciphers;
2016 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2017 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2018 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2019 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2020 cbinfo->server_cipher_list = expciphers;
2023 /* If this is a host for which certificate verification is mandatory or
2024 optional, set up appropriately. */
2026 tls_in.certificate_verified = FALSE;
2028 tls_in.dane_verified = FALSE;
2030 server_verify_callback_called = FALSE;
2032 if (verify_check_host(&tls_verify_hosts) == OK)
2034 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2035 FALSE, verify_callback_server, errstr);
2036 if (rc != OK) return rc;
2037 server_verify_optional = FALSE;
2039 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2041 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2042 TRUE, verify_callback_server, errstr);
2043 if (rc != OK) return rc;
2044 server_verify_optional = TRUE;
2047 /* Prepare for new connection */
2049 if (!(server_ssl = SSL_new(server_ctx)))
2050 return tls_error(US"SSL_new", NULL, NULL, errstr);
2052 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2054 * With the SSL_clear(), we get strange interoperability bugs with
2055 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2056 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2058 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2059 * session shutdown. In this case, we have a brand new object and there's no
2060 * obvious reason to immediately clear it. I'm guessing that this was
2061 * originally added because of incomplete initialisation which the clear fixed,
2062 * in some historic release.
2065 /* Set context and tell client to go ahead, except in the case of TLS startup
2066 on connection, where outputting anything now upsets the clients and tends to
2067 make them disconnect. We need to have an explicit fflush() here, to force out
2068 the response. Other smtp_printf() calls do not need it, because in non-TLS
2069 mode, the fflush() happens when smtp_getc() is called. */
2071 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2072 if (!tls_in.on_connect)
2074 smtp_printf("220 TLS go ahead\r\n", FALSE);
2078 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2079 that the OpenSSL library doesn't. */
2081 SSL_set_wfd(server_ssl, fileno(smtp_out));
2082 SSL_set_rfd(server_ssl, fileno(smtp_in));
2083 SSL_set_accept_state(server_ssl);
2085 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2087 sigalrm_seen = FALSE;
2088 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2089 rc = SSL_accept(server_ssl);
2094 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2098 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2100 /* TLS has been set up. Adjust the input functions to read via TLS,
2101 and initialize things. */
2103 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2105 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
2106 tls_in.cipher = cipherbuf;
2111 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
2112 debug_printf("Shared ciphers: %s\n", buf);
2115 /* Record the certificate we presented */
2117 X509 * crt = SSL_get_certificate(server_ssl);
2118 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2121 /* Only used by the server-side tls (tls_in), including tls_getc.
2122 Client-side (tls_out) reads (seem to?) go via
2123 smtp_read_response()/ip_recv().
2124 Hence no need to duplicate for _in and _out.
2126 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2127 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2128 ssl_xfer_eof = ssl_xfer_error = FALSE;
2130 receive_getc = tls_getc;
2131 receive_getbuf = tls_getbuf;
2132 receive_get_cache = tls_get_cache;
2133 receive_ungetc = tls_ungetc;
2134 receive_feof = tls_feof;
2135 receive_ferror = tls_ferror;
2136 receive_smtp_buffered = tls_smtp_buffered;
2138 tls_in.active.sock = fileno(smtp_out);
2139 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2147 tls_client_basic_ctx_init(SSL_CTX * ctx,
2148 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2152 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2153 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2154 the specified host patterns if one of them is defined */
2156 if ( ( !ob->tls_verify_hosts
2157 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2159 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
2161 client_verify_optional = FALSE;
2162 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
2163 client_verify_optional = TRUE;
2167 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2168 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2172 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
2174 cbinfo->verify_cert_hostnames =
2176 string_domain_utf8_to_alabel(host->name, NULL);
2180 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2181 cbinfo->verify_cert_hostnames);
2189 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2193 const char * hostnames[2] = { CS host->name, NULL };
2196 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2197 return tls_error(US"hostnames load", host, NULL, errstr);
2199 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2201 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2202 ) if (rr->type == T_TLSA)
2204 const uschar * p = rr->data;
2205 uint8_t usage, selector, mtype;
2206 const char * mdname;
2210 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2211 if (usage != 2 && usage != 3) continue;
2218 default: continue; /* Only match-types 0, 1, 2 are supported */
2219 case 0: mdname = NULL; break;
2220 case 1: mdname = "sha256"; break;
2221 case 2: mdname = "sha512"; break;
2225 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2228 return tls_error(US"tlsa load", host, NULL, errstr);
2229 case 0: /* action not taken */
2233 tls_out.tlsa_usage |= 1<<usage;
2239 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2242 #endif /*SUPPORT_DANE*/
2246 /*************************************************
2247 * Start a TLS session in a client *
2248 *************************************************/
2250 /* Called from the smtp transport after STARTTLS has been accepted.
2253 fd the fd of the connection
2254 host connected host (for messages)
2255 addr the first address
2256 tb transport (always smtp)
2257 tlsa_dnsa tlsa lookup, if DANE, else null
2258 tlsp record details of channel configuration
2259 errstr error string pointer
2261 Returns: Pointer to TLS session context, or NULL on error
2265 tls_client_start(int fd, host_item *host, address_item *addr,
2266 transport_instance * tb,
2268 dns_answer * tlsa_dnsa,
2270 tls_support * tlsp, uschar ** errstr)
2272 smtp_transport_options_block * ob =
2273 (smtp_transport_options_block *)tb->options_block;
2274 exim_openssl_client_tls_ctx * exim_client_ctx;
2275 static uschar peerdn[256];
2276 uschar * expciphers;
2278 static uschar cipherbuf[256];
2280 #ifndef DISABLE_OCSP
2281 BOOL request_ocsp = FALSE;
2282 BOOL require_ocsp = FALSE;
2286 store_pool = POOL_PERM;
2287 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx));
2291 tlsp->tlsa_usage = 0;
2294 #ifndef DISABLE_OCSP
2296 # ifdef SUPPORT_DANE
2298 && ob->hosts_request_ocsp[0] == '*'
2299 && ob->hosts_request_ocsp[1] == '\0'
2302 /* Unchanged from default. Use a safer one under DANE */
2303 request_ocsp = TRUE;
2304 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2305 " {= {4}{$tls_out_tlsa_usage}} } "
2311 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
2312 request_ocsp = TRUE;
2314 # ifdef SUPPORT_DANE
2318 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2322 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
2323 ob->tls_certificate, ob->tls_privatekey,
2324 #ifndef DISABLE_OCSP
2325 (void *)(long)request_ocsp,
2327 addr, &client_static_cbinfo, errstr);
2328 if (rc != OK) return NULL;
2330 tlsp->certificate_verified = FALSE;
2331 client_verify_callback_called = FALSE;
2337 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2338 other failures should be treated as problems. */
2339 if (ob->dane_require_tls_ciphers &&
2340 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2341 &expciphers, errstr))
2343 if (expciphers && *expciphers == '\0')
2348 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2349 &expciphers, errstr))
2352 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2353 are separated by underscores. So that I can use either form in my tests, and
2354 also for general convenience, we turn underscores into hyphens here. */
2358 uschar *s = expciphers;
2359 while (*s) { if (*s == '_') *s = '-'; s++; }
2360 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2361 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
2363 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2371 SSL_CTX_set_verify(exim_client_ctx->ctx,
2372 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2373 verify_callback_client_dane);
2375 if (!DANESSL_library_init())
2377 tls_error(US"library init", host, NULL, errstr);
2380 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
2382 tls_error(US"context init", host, NULL, errstr);
2390 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
2391 client_static_cbinfo, errstr) != OK)
2394 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
2396 tls_error(US"SSL_new", host, NULL, errstr);
2399 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
2400 SSL_set_fd(exim_client_ctx->ssl, fd);
2401 SSL_set_connect_state(exim_client_ctx->ssl);
2405 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
2409 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2411 else if (!Ustrlen(tlsp->sni))
2415 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2416 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
2417 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
2419 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2427 if (dane_tlsa_load(exim_client_ctx->ssl, host, tlsa_dnsa, errstr) != OK)
2431 #ifndef DISABLE_OCSP
2432 /* Request certificate status at connection-time. If the server
2433 does OCSP stapling we will get the callback (set in tls_init()) */
2434 # ifdef SUPPORT_DANE
2438 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2439 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2441 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2442 this means we avoid the OCSP request, we wasted the setup
2443 cost in tls_init(). */
2444 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2445 request_ocsp = require_ocsp
2446 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2453 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
2454 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2455 tlsp->ocsp = OCSP_NOT_RESP;
2459 #ifndef DISABLE_EVENT
2460 client_static_cbinfo->event_action = tb->event_action;
2463 /* There doesn't seem to be a built-in timeout on connection. */
2465 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2466 sigalrm_seen = FALSE;
2467 alarm(ob->command_timeout);
2468 rc = SSL_connect(exim_client_ctx->ssl);
2473 DANESSL_cleanup(exim_client_ctx->ssl);
2478 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
2482 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2484 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
2486 construct_cipher_name(exim_client_ctx->ssl, cipherbuf, sizeof(cipherbuf), &tlsp->bits);
2487 tlsp->cipher = cipherbuf;
2489 /* Record the certificate we presented */
2491 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
2492 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
2495 tlsp->active.sock = fd;
2496 tlsp->active.tls_ctx = exim_client_ctx;
2497 return exim_client_ctx;
2505 tls_refill(unsigned lim)
2510 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2511 ssl_xfer_buffer, ssl_xfer_buffer_size);
2513 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2514 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2515 MIN(ssl_xfer_buffer_size, lim));
2516 error = SSL_get_error(server_ssl, inbytes);
2517 if (smtp_receive_timeout > 0) alarm(0);
2519 if (had_command_timeout) /* set by signal handler */
2520 smtp_command_timeout_exit(); /* does not return */
2521 if (had_command_sigterm)
2522 smtp_command_sigterm_exit();
2523 if (had_data_timeout)
2524 smtp_data_timeout_exit();
2525 if (had_data_sigint)
2526 smtp_data_sigint_exit();
2528 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2529 closed down, not that the socket itself has been closed down. Revert to
2530 non-SSL handling. */
2534 case SSL_ERROR_NONE:
2537 case SSL_ERROR_ZERO_RETURN:
2538 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2540 receive_getc = smtp_getc;
2541 receive_getbuf = smtp_getbuf;
2542 receive_get_cache = smtp_get_cache;
2543 receive_ungetc = smtp_ungetc;
2544 receive_feof = smtp_feof;
2545 receive_ferror = smtp_ferror;
2546 receive_smtp_buffered = smtp_buffered;
2548 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2549 SSL_shutdown(server_ssl);
2551 #ifndef DISABLE_OCSP
2552 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2553 server_static_cbinfo->verify_stack = NULL;
2555 SSL_free(server_ssl);
2556 SSL_CTX_free(server_ctx);
2559 tls_in.active.sock = -1;
2560 tls_in.active.tls_ctx = NULL;
2562 tls_in.cipher = NULL;
2563 tls_in.peerdn = NULL;
2568 /* Handle genuine errors */
2570 ERR_error_string(ERR_get_error(), ssl_errstring);
2571 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2572 ssl_xfer_error = TRUE;
2576 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2577 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
2578 debug_printf(" - syscall %s\n", strerror(errno));
2579 ssl_xfer_error = TRUE;
2583 #ifndef DISABLE_DKIM
2584 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2586 ssl_xfer_buffer_hwm = inbytes;
2587 ssl_xfer_buffer_lwm = 0;
2592 /*************************************************
2593 * TLS version of getc *
2594 *************************************************/
2596 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2597 it refills the buffer via the SSL reading function.
2599 Arguments: lim Maximum amount to read/buffer
2600 Returns: the next character or EOF
2602 Only used by the server-side TLS.
2606 tls_getc(unsigned lim)
2608 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2609 if (!tls_refill(lim))
2610 return ssl_xfer_error ? EOF : smtp_getc(lim);
2612 /* Something in the buffer; return next uschar */
2614 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2618 tls_getbuf(unsigned * len)
2623 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2624 if (!tls_refill(*len))
2626 if (!ssl_xfer_error) return smtp_getbuf(len);
2631 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
2633 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
2634 ssl_xfer_buffer_lwm += size;
2643 #ifndef DISABLE_DKIM
2644 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2646 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
2652 tls_could_read(void)
2654 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
2658 /*************************************************
2659 * Read bytes from TLS channel *
2660 *************************************************/
2664 ct_ctx client context pointer, or NULL for the one global server context
2668 Returns: the number of bytes read
2669 -1 after a failed read
2671 Only used by the client-side TLS.
2675 tls_read(void * ct_ctx, uschar *buff, size_t len)
2677 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
2681 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2682 buff, (unsigned int)len);
2684 inbytes = SSL_read(ssl, CS buff, len);
2685 error = SSL_get_error(ssl, inbytes);
2687 if (error == SSL_ERROR_ZERO_RETURN)
2689 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2692 else if (error != SSL_ERROR_NONE)
2702 /*************************************************
2703 * Write bytes down TLS channel *
2704 *************************************************/
2708 ct_ctx client context pointer, or NULL for the one global server context
2711 more further data expected soon
2713 Returns: the number of bytes after a successful write,
2714 -1 after a failed write
2716 Used by both server-side and client-side TLS.
2720 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
2722 int outbytes, error, left;
2723 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
2724 static gstring * corked = NULL;
2726 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
2727 buff, (unsigned long)len, more ? ", more" : "");
2729 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2730 "more" is notified. This hack is only ok if small amounts are involved AND only
2731 one stream does it, in one context (i.e. no store reset). Currently it is used
2732 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2734 if (!ct_ctx && (more || corked))
2736 corked = string_catn(corked, buff, len);
2739 buff = CUS corked->s;
2744 for (left = len; left > 0;)
2746 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
2747 outbytes = SSL_write(ssl, CS buff, left);
2748 error = SSL_get_error(ssl, outbytes);
2749 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2753 ERR_error_string(ERR_get_error(), ssl_errstring);
2754 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2757 case SSL_ERROR_NONE:
2762 case SSL_ERROR_ZERO_RETURN:
2763 log_write(0, LOG_MAIN, "SSL channel closed on write");
2766 case SSL_ERROR_SYSCALL:
2767 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2768 sender_fullhost ? sender_fullhost : US"<unknown>",
2773 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2782 /*************************************************
2783 * Close down a TLS session *
2784 *************************************************/
2786 /* This is also called from within a delivery subprocess forked from the
2787 daemon, to shut down the TLS library, without actually doing a shutdown (which
2788 would tamper with the SSL session in the parent process).
2791 ct_ctx client TLS context pointer, or NULL for the one global server context
2792 shutdown 1 if TLS close-alert is to be sent,
2793 2 if also response to be waited for
2797 Used by both server-side and client-side TLS.
2801 tls_close(void * ct_ctx, int shutdown)
2803 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
2804 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
2805 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
2806 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
2808 if (*fdp < 0) return; /* TLS was not active */
2813 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2814 shutdown > 1 ? " (with response-wait)" : "");
2816 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
2820 rc = SSL_shutdown(*sslp); /* wait for response */
2824 if (rc < 0) DEBUG(D_tls)
2826 ERR_error_string(ERR_get_error(), ssl_errstring);
2827 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
2831 #ifndef DISABLE_OCSP
2832 if (!o_ctx) /* server side */
2834 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2835 server_static_cbinfo->verify_stack = NULL;
2839 SSL_CTX_free(*ctxp);
2849 /*************************************************
2850 * Let tls_require_ciphers be checked at startup *
2851 *************************************************/
2853 /* The tls_require_ciphers option, if set, must be something which the
2856 Returns: NULL on success, or error message
2860 tls_validate_require_cipher(void)
2863 uschar *s, *expciphers, *err;
2865 /* this duplicates from tls_init(), we need a better "init just global
2866 state, for no specific purpose" singleton function of our own */
2868 SSL_load_error_strings();
2869 OpenSSL_add_ssl_algorithms();
2870 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2871 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2872 list of available digests. */
2873 EVP_add_digest(EVP_sha256());
2876 if (!(tls_require_ciphers && *tls_require_ciphers))
2879 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
2881 return US"failed to expand tls_require_ciphers";
2883 if (!(expciphers && *expciphers))
2886 /* normalisation ripped from above */
2888 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2892 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
2893 if (!(ctx = SSL_CTX_new(TLS_server_method())))
2895 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
2898 ERR_error_string(ERR_get_error(), ssl_errstring);
2899 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2903 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2905 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2907 ERR_error_string(ERR_get_error(), ssl_errstring);
2908 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
2909 expciphers, ssl_errstring);
2920 /*************************************************
2921 * Report the library versions. *
2922 *************************************************/
2924 /* There have historically been some issues with binary compatibility in
2925 OpenSSL libraries; if Exim (like many other applications) is built against
2926 one version of OpenSSL but the run-time linker picks up another version,
2927 it can result in serious failures, including crashing with a SIGSEGV. So
2928 report the version found by the compiler and the run-time version.
2930 Note: some OS vendors backport security fixes without changing the version
2931 number/string, and the version date remains unchanged. The _build_ date
2932 will change, so we can more usefully assist with version diagnosis by also
2933 reporting the build date.
2935 Arguments: a FILE* to print the results to
2940 tls_version_report(FILE *f)
2942 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2945 OPENSSL_VERSION_TEXT,
2946 SSLeay_version(SSLEAY_VERSION),
2947 SSLeay_version(SSLEAY_BUILT_ON));
2948 /* third line is 38 characters for the %s and the line is 73 chars long;
2949 the OpenSSL output includes a "built on: " prefix already. */
2955 /*************************************************
2956 * Random number generation *
2957 *************************************************/
2959 /* Pseudo-random number generation. The result is not expected to be
2960 cryptographically strong but not so weak that someone will shoot themselves
2961 in the foot using it as a nonce in input in some email header scheme or
2962 whatever weirdness they'll twist this into. The result should handle fork()
2963 and avoid repeating sequences. OpenSSL handles that for us.
2967 Returns a random number in range [0, max-1]
2971 vaguely_random_number(int max)
2975 static pid_t pidlast = 0;
2978 uschar smallbuf[sizeof(r)];
2984 if (pidnow != pidlast)
2986 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2987 is unique for each thread", this doesn't apparently apply across processes,
2988 so our own warning from vaguely_random_number_fallback() applies here too.
2989 Fix per PostgreSQL. */
2995 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2999 gettimeofday(&r.tv, NULL);
3002 RAND_seed(US (&r), sizeof(r));
3004 /* We're after pseudo-random, not random; if we still don't have enough data
3005 in the internal PRNG then our options are limited. We could sleep and hope
3006 for entropy to come along (prayer technique) but if the system is so depleted
3007 in the first place then something is likely to just keep taking it. Instead,
3008 we'll just take whatever little bit of pseudo-random we can still manage to
3011 needed_len = sizeof(r);
3012 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3013 asked for a number less than 10. */
3014 for (r = max, i = 0; r; ++i)
3020 #ifdef EXIM_HAVE_RAND_PSEUDO
3021 /* We do not care if crypto-strong */
3022 i = RAND_pseudo_bytes(smallbuf, needed_len);
3024 i = RAND_bytes(smallbuf, needed_len);
3030 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3031 return vaguely_random_number_fallback(max);
3035 for (p = smallbuf; needed_len; --needed_len, ++p)
3041 /* We don't particularly care about weighted results; if someone wants
3042 smooth distribution and cares enough then they should submit a patch then. */
3049 /*************************************************
3050 * OpenSSL option parse *
3051 *************************************************/
3053 /* Parse one option for tls_openssl_options_parse below
3056 name one option name
3057 value place to store a value for it
3058 Returns success or failure in parsing
3061 struct exim_openssl_option {
3065 /* We could use a macro to expand, but we need the ifdef and not all the
3066 options document which version they were introduced in. Policylet: include
3067 all options unless explicitly for DTLS, let the administrator choose which
3070 This list is current as of:
3072 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
3074 static struct exim_openssl_option exim_openssl_options[] = {
3075 /* KEEP SORTED ALPHABETICALLY! */
3077 { US"all", SSL_OP_ALL },
3079 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
3080 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
3082 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
3083 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
3085 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
3086 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
3088 #ifdef SSL_OP_EPHEMERAL_RSA
3089 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
3091 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
3092 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
3094 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
3095 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
3097 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
3098 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
3100 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
3101 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
3103 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
3104 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
3106 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
3107 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
3109 #ifdef SSL_OP_NO_COMPRESSION
3110 { US"no_compression", SSL_OP_NO_COMPRESSION },
3112 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
3113 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
3115 #ifdef SSL_OP_NO_SSLv2
3116 { US"no_sslv2", SSL_OP_NO_SSLv2 },
3118 #ifdef SSL_OP_NO_SSLv3
3119 { US"no_sslv3", SSL_OP_NO_SSLv3 },
3121 #ifdef SSL_OP_NO_TICKET
3122 { US"no_ticket", SSL_OP_NO_TICKET },
3124 #ifdef SSL_OP_NO_TLSv1
3125 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
3127 #ifdef SSL_OP_NO_TLSv1_1
3128 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
3129 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
3130 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
3132 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
3135 #ifdef SSL_OP_NO_TLSv1_2
3136 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
3138 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
3139 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
3141 #ifdef SSL_OP_SINGLE_DH_USE
3142 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
3144 #ifdef SSL_OP_SINGLE_ECDH_USE
3145 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
3147 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
3148 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
3150 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
3151 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
3153 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
3154 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
3156 #ifdef SSL_OP_TLS_D5_BUG
3157 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
3159 #ifdef SSL_OP_TLS_ROLLBACK_BUG
3160 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
3163 static int exim_openssl_options_size =
3164 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
3168 tls_openssl_one_option_parse(uschar *name, long *value)
3171 int last = exim_openssl_options_size;
3172 while (last > first)
3174 int middle = (first + last)/2;
3175 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3178 *value = exim_openssl_options[middle].value;
3192 /*************************************************
3193 * OpenSSL option parsing logic *
3194 *************************************************/
3196 /* OpenSSL has a number of compatibility options which an administrator might
3197 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3198 we look like log_selector.
3201 option_spec the administrator-supplied string of options
3202 results ptr to long storage for the options bitmap
3203 Returns success or failure
3207 tls_openssl_options_parse(uschar *option_spec, long *results)
3212 BOOL adding, item_parsed;
3214 result = SSL_OP_NO_TICKET;
3215 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3216 * from default because it increases BEAST susceptibility. */
3217 #ifdef SSL_OP_NO_SSLv2
3218 result |= SSL_OP_NO_SSLv2;
3220 #ifdef SSL_OP_SINGLE_DH_USE
3221 result |= SSL_OP_SINGLE_DH_USE;
3230 for (s=option_spec; *s != '\0'; /**/)
3232 while (isspace(*s)) ++s;
3235 if (*s != '+' && *s != '-')
3237 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3238 "+ or - expected but found \"%s\"\n", s);
3241 adding = *s++ == '+';
3242 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3245 item_parsed = tls_openssl_one_option_parse(s, &item);
3249 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3252 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3253 adding ? "adding" : "removing", result, item, s);
3267 /* End of tls-openssl.c */