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 (f.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 return SSL_TLSEXT_ERR_NOACK;
1255 #ifndef DISABLE_OCSP
1256 if (cbinfo->u_ocsp.server.file)
1258 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1259 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1263 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1264 verify_callback_server, &dummy_errstr)) != OK)
1265 return SSL_TLSEXT_ERR_NOACK;
1267 /* do this after setup_certs, because this can require the certs for verifying
1268 OCSP information. */
1269 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1270 return SSL_TLSEXT_ERR_NOACK;
1272 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1273 SSL_set_SSL_CTX(s, server_sni);
1275 return SSL_TLSEXT_ERR_OK;
1277 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1282 #ifndef DISABLE_OCSP
1284 /*************************************************
1285 * Callback to handle OCSP Stapling *
1286 *************************************************/
1288 /* Called when acting as server during the TLS session setup if the client
1289 requests OCSP information with a Certificate Status Request.
1291 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1297 tls_server_stapling_cb(SSL *s, void *arg)
1299 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1300 uschar *response_der; /*XXX blob */
1301 int response_der_len;
1303 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1304 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1305 buggy in current OpenSSL; it returns the last cert loaded always rather than
1306 the one actually presented. So we can't support a stack of OCSP proofs at
1310 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1311 cbinfo->u_ocsp.server.response ? "have" : "lack");
1313 tls_in.ocsp = OCSP_NOT_RESP;
1314 if (!cbinfo->u_ocsp.server.response)
1315 return SSL_TLSEXT_ERR_NOACK;
1317 response_der = NULL;
1318 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1320 if (response_der_len <= 0)
1321 return SSL_TLSEXT_ERR_NOACK;
1323 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1324 tls_in.ocsp = OCSP_VFIED;
1325 return SSL_TLSEXT_ERR_OK;
1330 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1332 BIO_printf(bp, "\t%s: ", str);
1333 ASN1_GENERALIZEDTIME_print(bp, time);
1338 tls_client_stapling_cb(SSL *s, void *arg)
1340 tls_ext_ctx_cb * cbinfo = arg;
1341 const unsigned char * p;
1343 OCSP_RESPONSE * rsp;
1344 OCSP_BASICRESP * bs;
1347 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1348 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1351 /* Expect this when we requested ocsp but got none */
1352 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1353 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1355 DEBUG(D_tls) debug_printf(" null\n");
1356 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1359 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1361 tls_out.ocsp = OCSP_FAILED;
1362 if (LOGGING(tls_cipher))
1363 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1365 DEBUG(D_tls) debug_printf(" parse error\n");
1369 if(!(bs = OCSP_response_get1_basic(rsp)))
1371 tls_out.ocsp = OCSP_FAILED;
1372 if (LOGGING(tls_cipher))
1373 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1375 DEBUG(D_tls) debug_printf(" error parsing response\n");
1376 OCSP_RESPONSE_free(rsp);
1380 /* We'd check the nonce here if we'd put one in the request. */
1381 /* However that would defeat cacheability on the server so we don't. */
1383 /* This section of code reworked from OpenSSL apps source;
1384 The OpenSSL Project retains copyright:
1385 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1390 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1392 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1394 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1396 /* Use the chain that verified the server cert to verify the stapled info */
1397 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1399 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1400 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1402 tls_out.ocsp = OCSP_FAILED;
1403 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1404 "Received TLS cert status response, itself unverifiable: %s",
1405 ERR_reason_error_string(ERR_peek_error()));
1406 BIO_printf(bp, "OCSP response verify failure\n");
1407 ERR_print_errors(bp);
1408 OCSP_RESPONSE_print(bp, rsp, 0);
1412 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1414 /*XXX So we have a good stapled OCSP status. How do we know
1415 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1416 OCSP_resp_find_status() which matches on a cert id, which presumably
1417 we should use. Making an id needs OCSP_cert_id_new(), which takes
1418 issuerName, issuerKey, serialNumber. Are they all in the cert?
1420 For now, carry on blindly accepting the resp. */
1423 OCSP_SINGLERESP * single;
1425 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1426 if (OCSP_resp_count(bs) != 1)
1428 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1429 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1432 tls_out.ocsp = OCSP_FAILED;
1433 log_write(0, LOG_MAIN, "OCSP stapling "
1434 "with multiple responses not handled");
1437 single = OCSP_resp_get0(bs, 0);
1438 status = OCSP_single_get0_status(single, &reason, &rev,
1439 &thisupd, &nextupd);
1442 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1443 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1444 if (!OCSP_check_validity(thisupd, nextupd,
1445 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1447 tls_out.ocsp = OCSP_FAILED;
1448 DEBUG(D_tls) ERR_print_errors(bp);
1449 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1453 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1454 OCSP_cert_status_str(status));
1457 case V_OCSP_CERTSTATUS_GOOD:
1458 tls_out.ocsp = OCSP_VFIED;
1461 case V_OCSP_CERTSTATUS_REVOKED:
1462 tls_out.ocsp = OCSP_FAILED;
1463 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1464 reason != -1 ? "; reason: " : "",
1465 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1466 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1469 tls_out.ocsp = OCSP_FAILED;
1470 log_write(0, LOG_MAIN,
1471 "Server certificate status unknown, in OCSP stapling");
1476 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1481 OCSP_RESPONSE_free(rsp);
1484 #endif /*!DISABLE_OCSP*/
1487 /*************************************************
1488 * Initialize for TLS *
1489 *************************************************/
1491 /* Called from both server and client code, to do preliminary initialization
1492 of the library. We allocate and return a context structure.
1495 ctxp returned SSL context
1496 host connected host, if client; NULL if server
1497 dhparam DH parameter file
1498 certificate certificate file
1499 privatekey private key
1500 ocsp_file file of stapling info (server); flag for require ocsp (client)
1501 addr address if client; NULL if server (for some randomness)
1502 cbp place to put allocated callback context
1503 errstr error string pointer
1505 Returns: OK/DEFER/FAIL
1509 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1511 #ifndef DISABLE_OCSP
1512 uschar *ocsp_file, /*XXX stack, in server*/
1514 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
1519 tls_ext_ctx_cb * cbinfo;
1521 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1522 cbinfo->certificate = certificate;
1523 cbinfo->privatekey = privatekey;
1524 cbinfo->is_server = host==NULL;
1525 #ifndef DISABLE_OCSP
1526 cbinfo->verify_stack = NULL;
1529 cbinfo->u_ocsp.server.file = ocsp_file;
1530 cbinfo->u_ocsp.server.file_expanded = NULL;
1531 cbinfo->u_ocsp.server.response = NULL;
1534 cbinfo->u_ocsp.client.verify_store = NULL;
1536 cbinfo->dhparam = dhparam;
1537 cbinfo->server_cipher_list = NULL;
1538 cbinfo->host = host;
1539 #ifndef DISABLE_EVENT
1540 cbinfo->event_action = NULL;
1543 SSL_load_error_strings(); /* basic set up */
1544 OpenSSL_add_ssl_algorithms();
1546 #ifdef EXIM_HAVE_SHA256
1547 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1548 list of available digests. */
1549 EVP_add_digest(EVP_sha256());
1552 /* Create a context.
1553 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1554 negotiation in the different methods; as far as I can tell, the only
1555 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1556 when OpenSSL is built without SSLv2 support.
1557 By disabling with openssl_options, we can let admins re-enable with the
1560 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1561 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1563 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1565 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1567 /* It turns out that we need to seed the random number generator this early in
1568 order to get the full complement of ciphers to work. It took me roughly a day
1569 of work to discover this by experiment.
1571 On systems that have /dev/urandom, SSL may automatically seed itself from
1572 there. Otherwise, we have to make something up as best we can. Double check
1578 gettimeofday(&r.tv, NULL);
1581 RAND_seed(US (&r), sizeof(r));
1582 RAND_seed(US big_buffer, big_buffer_size);
1583 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1586 return tls_error(US"RAND_status", host,
1587 US"unable to seed random number generator", errstr);
1590 /* Set up the information callback, which outputs if debugging is at a suitable
1593 DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1595 /* Automatically re-try reads/writes after renegotiation. */
1596 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1598 /* Apply administrator-supplied work-arounds.
1599 Historically we applied just one requested option,
1600 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1601 moved to an administrator-controlled list of options to specify and
1602 grandfathered in the first one as the default value for "openssl_options".
1604 No OpenSSL version number checks: the options we accept depend upon the
1605 availability of the option value macros from OpenSSL. */
1607 if (!tls_openssl_options_parse(openssl_options, &init_options))
1608 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1612 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1613 if (!(SSL_CTX_set_options(ctx, init_options)))
1614 return tls_error(string_sprintf(
1615 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
1618 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1620 /* We'd like to disable session cache unconditionally, but foolish Outlook
1621 Express clients then give up the first TLS connection and make a second one
1622 (which works). Only when there is an IMAP service on the same machine.
1623 Presumably OE is trying to use the cache for A on B. Leave it enabled for
1624 now, until we work out a decent way of presenting control to the config. It
1625 will never be used because we use a new context every time. */
1627 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
1630 /* Initialize with DH parameters if supplied */
1631 /* Initialize ECDH temp key parameter selection */
1633 if ( !init_dh(ctx, dhparam, host, errstr)
1634 || !init_ecdh(ctx, host, errstr)
1638 /* Set up certificate and key (and perhaps OCSP info) */
1640 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
1643 /* If we need to handle SNI or OCSP, do so */
1645 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1646 # ifndef DISABLE_OCSP
1647 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1649 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1654 if (!host) /* server */
1656 # ifndef DISABLE_OCSP
1657 /* We check u_ocsp.server.file, not server.response, because we care about if
1658 the option exists, not what the current expansion might be, as SNI might
1659 change the certificate and OCSP file in use between now and the time the
1660 callback is invoked. */
1661 if (cbinfo->u_ocsp.server.file)
1663 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
1664 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1667 /* We always do this, so that $tls_sni is available even if not used in
1669 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
1670 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
1672 # ifndef DISABLE_OCSP
1674 if(ocsp_file) /* wanting stapling */
1676 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1678 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1681 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
1682 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1687 cbinfo->verify_cert_hostnames = NULL;
1689 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1690 /* Set up the RSA callback */
1691 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
1694 /* Finally, set the timeout, and we are done */
1696 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
1697 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1708 /*************************************************
1709 * Get name of cipher in use *
1710 *************************************************/
1713 Argument: pointer to an SSL structure for the connection
1714 buffer to use for answer
1716 pointer to number of bits for cipher
1721 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1723 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
1724 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1725 the accessor functions use const in the prototype. */
1727 const uschar * ver = CUS SSL_get_version(ssl);
1728 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1730 SSL_CIPHER_get_bits(c, bits);
1732 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1733 SSL_CIPHER_get_name(c), *bits);
1735 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1740 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1742 /*XXX we might consider a list-of-certs variable for the cert chain.
1743 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1744 in list-handling functions, also consider the difference between the entire
1745 chain and the elements sent by the peer. */
1747 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1748 if (!tlsp->peercert)
1749 tlsp->peercert = SSL_get_peer_certificate(ssl);
1750 /* Beware anonymous ciphers which lead to server_cert being NULL */
1753 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1754 peerdn[bsize-1] = '\0';
1755 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1758 tlsp->peerdn = NULL;
1765 /*************************************************
1766 * Set up for verifying certificates *
1767 *************************************************/
1769 #ifndef DISABLE_OCSP
1770 /* Load certs from file, return TRUE on success */
1773 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1778 while (sk_X509_num(verify_stack) > 0)
1779 X509_free(sk_X509_pop(verify_stack));
1781 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1782 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1783 sk_X509_push(verify_stack, x);
1791 /* Called by both client and server startup; on the server possibly
1792 repeated after a Server Name Indication.
1795 sctx SSL_CTX* to initialise
1796 certs certs file or NULL
1797 crl CRL file or NULL
1798 host NULL in a server; the remote host in a client
1799 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1800 otherwise passed as FALSE
1801 cert_vfy_cb Callback function for certificate verification
1802 errstr error string pointer
1804 Returns: OK/DEFER/FAIL
1808 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1809 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
1811 uschar *expcerts, *expcrl;
1813 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
1815 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
1817 if (expcerts && *expcerts)
1819 /* Tell the library to use its compiled-in location for the system default
1820 CA bundle. Then add the ones specified in the config, if any. */
1822 if (!SSL_CTX_set_default_verify_paths(sctx))
1823 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
1825 if (Ustrcmp(expcerts, "system") != 0)
1827 struct stat statbuf;
1829 if (Ustat(expcerts, &statbuf) < 0)
1831 log_write(0, LOG_MAIN|LOG_PANIC,
1832 "failed to stat %s for certificates", expcerts);
1838 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1839 { file = NULL; dir = expcerts; }
1842 file = expcerts; dir = NULL;
1843 #ifndef DISABLE_OCSP
1844 /* In the server if we will be offering an OCSP proof, load chain from
1845 file for verifying the OCSP proof at load time. */
1848 && statbuf.st_size > 0
1849 && server_static_cbinfo->u_ocsp.server.file
1850 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
1853 log_write(0, LOG_MAIN|LOG_PANIC,
1854 "failed to load cert chain from %s", file);
1860 /* If a certificate file is empty, the next function fails with an
1861 unhelpful error message. If we skip it, we get the correct behaviour (no
1862 certificates are recognized, but the error message is still misleading (it
1863 says no certificate was supplied). But this is better. */
1865 if ( (!file || statbuf.st_size > 0)
1866 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1867 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
1869 /* Load the list of CAs for which we will accept certs, for sending
1870 to the client. This is only for the one-file tls_verify_certificates
1872 If a list isn't loaded into the server, but
1873 some verify locations are set, the server end appears to make
1874 a wildcard request for client certs.
1875 Meanwhile, the client library as default behaviour *ignores* the list
1876 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1877 Because of this, and that the dir variant is likely only used for
1878 the public-CA bundle (not for a private CA), not worth fixing.
1882 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1884 SSL_CTX_set_client_CA_list(sctx, names);
1885 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1886 sk_X509_NAME_num(names));
1891 /* Handle a certificate revocation list. */
1893 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1895 /* This bit of code is now the version supplied by Lars Mainka. (I have
1896 merely reformatted it into the Exim code style.)
1898 "From here I changed the code to add support for multiple crl's
1899 in pem format in one file or to support hashed directory entries in
1900 pem format instead of a file. This method now uses the library function
1901 X509_STORE_load_locations to add the CRL location to the SSL context.
1902 OpenSSL will then handle the verify against CA certs and CRLs by
1903 itself in the verify callback." */
1905 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
1906 if (expcrl && *expcrl)
1908 struct stat statbufcrl;
1909 if (Ustat(expcrl, &statbufcrl) < 0)
1911 log_write(0, LOG_MAIN|LOG_PANIC,
1912 "failed to stat %s for certificates revocation lists", expcrl);
1917 /* is it a file or directory? */
1919 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1920 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1924 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1930 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1932 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1933 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
1935 /* setting the flags to check against the complete crl chain */
1937 X509_STORE_set_flags(cvstore,
1938 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1942 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1944 /* If verification is optional, don't fail if no certificate */
1946 SSL_CTX_set_verify(sctx,
1947 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1956 /*************************************************
1957 * Start a TLS session in a server *
1958 *************************************************/
1960 /* This is called when Exim is running as a server, after having received
1961 the STARTTLS command. It must respond to that command, and then negotiate
1965 require_ciphers allowed ciphers
1966 errstr pointer to error message
1968 Returns: OK on success
1969 DEFER for errors before the start of the negotiation
1970 FAIL for errors during the negotiation; the server can't
1975 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
1978 uschar * expciphers;
1979 tls_ext_ctx_cb * cbinfo;
1980 static uschar peerdn[256];
1981 static uschar cipherbuf[256];
1983 /* Check for previous activation */
1985 if (tls_in.active.sock >= 0)
1987 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
1988 smtp_printf("554 Already in TLS\r\n", FALSE);
1992 /* Initialize the SSL library. If it fails, it will already have logged
1995 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1996 #ifndef DISABLE_OCSP
1997 tls_ocsp_file, /*XXX stack*/
1999 NULL, &server_static_cbinfo, errstr);
2000 if (rc != OK) return rc;
2001 cbinfo = server_static_cbinfo;
2003 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2006 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2007 were historically separated by underscores. So that I can use either form in my
2008 tests, and also for general convenience, we turn underscores into hyphens here.
2010 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2011 for TLS 1.3 . Since we do not call it at present we get the default list:
2012 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2017 uschar * s = expciphers;
2018 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2019 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2020 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2021 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2022 cbinfo->server_cipher_list = expciphers;
2025 /* If this is a host for which certificate verification is mandatory or
2026 optional, set up appropriately. */
2028 tls_in.certificate_verified = FALSE;
2030 tls_in.dane_verified = FALSE;
2032 server_verify_callback_called = FALSE;
2034 if (verify_check_host(&tls_verify_hosts) == OK)
2036 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2037 FALSE, verify_callback_server, errstr);
2038 if (rc != OK) return rc;
2039 server_verify_optional = FALSE;
2041 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2043 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2044 TRUE, verify_callback_server, errstr);
2045 if (rc != OK) return rc;
2046 server_verify_optional = TRUE;
2049 /* Prepare for new connection */
2051 if (!(server_ssl = SSL_new(server_ctx)))
2052 return tls_error(US"SSL_new", NULL, NULL, errstr);
2054 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2056 * With the SSL_clear(), we get strange interoperability bugs with
2057 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2058 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2060 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2061 * session shutdown. In this case, we have a brand new object and there's no
2062 * obvious reason to immediately clear it. I'm guessing that this was
2063 * originally added because of incomplete initialisation which the clear fixed,
2064 * in some historic release.
2067 /* Set context and tell client to go ahead, except in the case of TLS startup
2068 on connection, where outputting anything now upsets the clients and tends to
2069 make them disconnect. We need to have an explicit fflush() here, to force out
2070 the response. Other smtp_printf() calls do not need it, because in non-TLS
2071 mode, the fflush() happens when smtp_getc() is called. */
2073 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2074 if (!tls_in.on_connect)
2076 smtp_printf("220 TLS go ahead\r\n", FALSE);
2080 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2081 that the OpenSSL library doesn't. */
2083 SSL_set_wfd(server_ssl, fileno(smtp_out));
2084 SSL_set_rfd(server_ssl, fileno(smtp_in));
2085 SSL_set_accept_state(server_ssl);
2087 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2089 sigalrm_seen = FALSE;
2090 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2091 rc = SSL_accept(server_ssl);
2096 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2100 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2102 /* TLS has been set up. Adjust the input functions to read via TLS,
2103 and initialize things. */
2105 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2107 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
2108 tls_in.cipher = cipherbuf;
2113 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
2114 debug_printf("Shared ciphers: %s\n", buf);
2117 /* Record the certificate we presented */
2119 X509 * crt = SSL_get_certificate(server_ssl);
2120 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2123 /* Only used by the server-side tls (tls_in), including tls_getc.
2124 Client-side (tls_out) reads (seem to?) go via
2125 smtp_read_response()/ip_recv().
2126 Hence no need to duplicate for _in and _out.
2128 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2129 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2130 ssl_xfer_eof = ssl_xfer_error = FALSE;
2132 receive_getc = tls_getc;
2133 receive_getbuf = tls_getbuf;
2134 receive_get_cache = tls_get_cache;
2135 receive_ungetc = tls_ungetc;
2136 receive_feof = tls_feof;
2137 receive_ferror = tls_ferror;
2138 receive_smtp_buffered = tls_smtp_buffered;
2140 tls_in.active.sock = fileno(smtp_out);
2141 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2149 tls_client_basic_ctx_init(SSL_CTX * ctx,
2150 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2154 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2155 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2156 the specified host patterns if one of them is defined */
2158 if ( ( !ob->tls_verify_hosts
2159 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2161 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2163 client_verify_optional = FALSE;
2164 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2165 client_verify_optional = TRUE;
2169 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2170 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2174 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2176 cbinfo->verify_cert_hostnames =
2178 string_domain_utf8_to_alabel(host->name, NULL);
2182 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2183 cbinfo->verify_cert_hostnames);
2191 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2195 const char * hostnames[2] = { CS host->name, NULL };
2198 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2199 return tls_error(US"hostnames load", host, NULL, errstr);
2201 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2203 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2204 ) if (rr->type == T_TLSA)
2206 const uschar * p = rr->data;
2207 uint8_t usage, selector, mtype;
2208 const char * mdname;
2212 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2213 if (usage != 2 && usage != 3) continue;
2220 default: continue; /* Only match-types 0, 1, 2 are supported */
2221 case 0: mdname = NULL; break;
2222 case 1: mdname = "sha256"; break;
2223 case 2: mdname = "sha512"; break;
2227 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2230 return tls_error(US"tlsa load", host, NULL, errstr);
2231 case 0: /* action not taken */
2235 tls_out.tlsa_usage |= 1<<usage;
2241 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2244 #endif /*SUPPORT_DANE*/
2248 /*************************************************
2249 * Start a TLS session in a client *
2250 *************************************************/
2252 /* Called from the smtp transport after STARTTLS has been accepted.
2255 fd the fd of the connection
2256 host connected host (for messages and option-tests)
2257 addr the first address (for some randomness; can be NULL)
2258 tb transport (always smtp)
2259 tlsa_dnsa tlsa lookup, if DANE, else null
2260 tlsp record details of channel configuration here; must be non-NULL
2261 errstr error string pointer
2263 Returns: Pointer to TLS session context, or NULL on error
2267 tls_client_start(int fd, host_item *host, address_item *addr,
2268 transport_instance * tb,
2270 dns_answer * tlsa_dnsa,
2272 tls_support * tlsp, uschar ** errstr)
2274 smtp_transport_options_block * ob = tb
2275 ? (smtp_transport_options_block *)tb->options_block
2276 : &smtp_transport_option_defaults;
2277 exim_openssl_client_tls_ctx * exim_client_ctx;
2278 static uschar peerdn[256];
2279 uschar * expciphers;
2281 static uschar cipherbuf[256];
2283 #ifndef DISABLE_OCSP
2284 BOOL request_ocsp = FALSE;
2285 BOOL require_ocsp = FALSE;
2289 store_pool = POOL_PERM;
2290 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx));
2294 tlsp->tlsa_usage = 0;
2297 #ifndef DISABLE_OCSP
2299 # ifdef SUPPORT_DANE
2301 && ob->hosts_request_ocsp[0] == '*'
2302 && ob->hosts_request_ocsp[1] == '\0'
2305 /* Unchanged from default. Use a safer one under DANE */
2306 request_ocsp = TRUE;
2307 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2308 " {= {4}{$tls_out_tlsa_usage}} } "
2314 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
2315 request_ocsp = TRUE;
2317 # ifdef SUPPORT_DANE
2321 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2325 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
2326 ob->tls_certificate, ob->tls_privatekey,
2327 #ifndef DISABLE_OCSP
2328 (void *)(long)request_ocsp,
2330 addr, &client_static_cbinfo, errstr);
2331 if (rc != OK) return NULL;
2333 tlsp->certificate_verified = FALSE;
2334 client_verify_callback_called = FALSE;
2340 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2341 other failures should be treated as problems. */
2342 if (ob->dane_require_tls_ciphers &&
2343 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2344 &expciphers, errstr))
2346 if (expciphers && *expciphers == '\0')
2351 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2352 &expciphers, errstr))
2355 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2356 are separated by underscores. So that I can use either form in my tests, and
2357 also for general convenience, we turn underscores into hyphens here. */
2361 uschar *s = expciphers;
2362 while (*s) { if (*s == '_') *s = '-'; s++; }
2363 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2364 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
2366 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2374 SSL_CTX_set_verify(exim_client_ctx->ctx,
2375 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2376 verify_callback_client_dane);
2378 if (!DANESSL_library_init())
2380 tls_error(US"library init", host, NULL, errstr);
2383 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
2385 tls_error(US"context init", host, NULL, errstr);
2393 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
2394 client_static_cbinfo, errstr) != OK)
2397 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
2399 tls_error(US"SSL_new", host, NULL, errstr);
2402 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
2403 SSL_set_fd(exim_client_ctx->ssl, fd);
2404 SSL_set_connect_state(exim_client_ctx->ssl);
2408 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
2412 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2414 else if (!Ustrlen(tlsp->sni))
2418 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2419 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
2420 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
2422 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2430 if (dane_tlsa_load(exim_client_ctx->ssl, host, tlsa_dnsa, errstr) != OK)
2434 #ifndef DISABLE_OCSP
2435 /* Request certificate status at connection-time. If the server
2436 does OCSP stapling we will get the callback (set in tls_init()) */
2437 # ifdef SUPPORT_DANE
2441 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2442 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2444 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2445 this means we avoid the OCSP request, we wasted the setup
2446 cost in tls_init(). */
2447 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
2448 request_ocsp = require_ocsp
2449 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2456 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
2457 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2458 tlsp->ocsp = OCSP_NOT_RESP;
2462 #ifndef DISABLE_EVENT
2463 client_static_cbinfo->event_action = tb ? tb->event_action : NULL;
2466 /* There doesn't seem to be a built-in timeout on connection. */
2468 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2469 sigalrm_seen = FALSE;
2470 alarm(ob->command_timeout);
2471 rc = SSL_connect(exim_client_ctx->ssl);
2476 DANESSL_cleanup(exim_client_ctx->ssl);
2481 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
2485 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2487 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
2489 construct_cipher_name(exim_client_ctx->ssl, cipherbuf, sizeof(cipherbuf), &tlsp->bits);
2490 tlsp->cipher = cipherbuf;
2492 /* Record the certificate we presented */
2494 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
2495 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
2498 tlsp->active.sock = fd;
2499 tlsp->active.tls_ctx = exim_client_ctx;
2500 return exim_client_ctx;
2508 tls_refill(unsigned lim)
2513 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2514 ssl_xfer_buffer, ssl_xfer_buffer_size);
2516 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2517 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2518 MIN(ssl_xfer_buffer_size, lim));
2519 error = SSL_get_error(server_ssl, inbytes);
2520 if (smtp_receive_timeout > 0) alarm(0);
2522 if (had_command_timeout) /* set by signal handler */
2523 smtp_command_timeout_exit(); /* does not return */
2524 if (had_command_sigterm)
2525 smtp_command_sigterm_exit();
2526 if (had_data_timeout)
2527 smtp_data_timeout_exit();
2528 if (had_data_sigint)
2529 smtp_data_sigint_exit();
2531 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2532 closed down, not that the socket itself has been closed down. Revert to
2533 non-SSL handling. */
2537 case SSL_ERROR_NONE:
2540 case SSL_ERROR_ZERO_RETURN:
2541 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2543 receive_getc = smtp_getc;
2544 receive_getbuf = smtp_getbuf;
2545 receive_get_cache = smtp_get_cache;
2546 receive_ungetc = smtp_ungetc;
2547 receive_feof = smtp_feof;
2548 receive_ferror = smtp_ferror;
2549 receive_smtp_buffered = smtp_buffered;
2551 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2552 SSL_shutdown(server_ssl);
2554 #ifndef DISABLE_OCSP
2555 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2556 server_static_cbinfo->verify_stack = NULL;
2558 SSL_free(server_ssl);
2559 SSL_CTX_free(server_ctx);
2562 tls_in.active.sock = -1;
2563 tls_in.active.tls_ctx = NULL;
2565 tls_in.cipher = NULL;
2566 tls_in.peerdn = NULL;
2571 /* Handle genuine errors */
2573 ERR_error_string(ERR_get_error(), ssl_errstring);
2574 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2575 ssl_xfer_error = TRUE;
2579 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2580 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
2581 debug_printf(" - syscall %s\n", strerror(errno));
2582 ssl_xfer_error = TRUE;
2586 #ifndef DISABLE_DKIM
2587 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2589 ssl_xfer_buffer_hwm = inbytes;
2590 ssl_xfer_buffer_lwm = 0;
2595 /*************************************************
2596 * TLS version of getc *
2597 *************************************************/
2599 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2600 it refills the buffer via the SSL reading function.
2602 Arguments: lim Maximum amount to read/buffer
2603 Returns: the next character or EOF
2605 Only used by the server-side TLS.
2609 tls_getc(unsigned lim)
2611 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2612 if (!tls_refill(lim))
2613 return ssl_xfer_error ? EOF : smtp_getc(lim);
2615 /* Something in the buffer; return next uschar */
2617 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2621 tls_getbuf(unsigned * len)
2626 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2627 if (!tls_refill(*len))
2629 if (!ssl_xfer_error) return smtp_getbuf(len);
2634 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
2636 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
2637 ssl_xfer_buffer_lwm += size;
2646 #ifndef DISABLE_DKIM
2647 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2649 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
2655 tls_could_read(void)
2657 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
2661 /*************************************************
2662 * Read bytes from TLS channel *
2663 *************************************************/
2667 ct_ctx client context pointer, or NULL for the one global server context
2671 Returns: the number of bytes read
2672 -1 after a failed read, including EOF
2674 Only used by the client-side TLS.
2678 tls_read(void * ct_ctx, uschar *buff, size_t len)
2680 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
2684 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2685 buff, (unsigned int)len);
2687 inbytes = SSL_read(ssl, CS buff, len);
2688 error = SSL_get_error(ssl, inbytes);
2690 if (error == SSL_ERROR_ZERO_RETURN)
2692 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2695 else if (error != SSL_ERROR_NONE)
2705 /*************************************************
2706 * Write bytes down TLS channel *
2707 *************************************************/
2711 ct_ctx client context pointer, or NULL for the one global server context
2714 more further data expected soon
2716 Returns: the number of bytes after a successful write,
2717 -1 after a failed write
2719 Used by both server-side and client-side TLS.
2723 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
2725 int outbytes, error, left;
2726 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
2727 static gstring * corked = NULL;
2729 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
2730 buff, (unsigned long)len, more ? ", more" : "");
2732 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2733 "more" is notified. This hack is only ok if small amounts are involved AND only
2734 one stream does it, in one context (i.e. no store reset). Currently it is used
2735 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2737 if (!ct_ctx && (more || corked))
2739 corked = string_catn(corked, buff, len);
2742 buff = CUS corked->s;
2747 for (left = len; left > 0;)
2749 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
2750 outbytes = SSL_write(ssl, CS buff, left);
2751 error = SSL_get_error(ssl, outbytes);
2752 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2756 ERR_error_string(ERR_get_error(), ssl_errstring);
2757 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2760 case SSL_ERROR_NONE:
2765 case SSL_ERROR_ZERO_RETURN:
2766 log_write(0, LOG_MAIN, "SSL channel closed on write");
2769 case SSL_ERROR_SYSCALL:
2770 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2771 sender_fullhost ? sender_fullhost : US"<unknown>",
2776 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2785 /*************************************************
2786 * Close down a TLS session *
2787 *************************************************/
2789 /* This is also called from within a delivery subprocess forked from the
2790 daemon, to shut down the TLS library, without actually doing a shutdown (which
2791 would tamper with the SSL session in the parent process).
2794 ct_ctx client TLS context pointer, or NULL for the one global server context
2795 shutdown 1 if TLS close-alert is to be sent,
2796 2 if also response to be waited for
2800 Used by both server-side and client-side TLS.
2804 tls_close(void * ct_ctx, int shutdown)
2806 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
2807 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
2808 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
2809 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
2811 if (*fdp < 0) return; /* TLS was not active */
2816 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2817 shutdown > 1 ? " (with response-wait)" : "");
2819 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
2823 rc = SSL_shutdown(*sslp); /* wait for response */
2827 if (rc < 0) DEBUG(D_tls)
2829 ERR_error_string(ERR_get_error(), ssl_errstring);
2830 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
2834 #ifndef DISABLE_OCSP
2835 if (!o_ctx) /* server side */
2837 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2838 server_static_cbinfo->verify_stack = NULL;
2842 SSL_CTX_free(*ctxp);
2852 /*************************************************
2853 * Let tls_require_ciphers be checked at startup *
2854 *************************************************/
2856 /* The tls_require_ciphers option, if set, must be something which the
2859 Returns: NULL on success, or error message
2863 tls_validate_require_cipher(void)
2866 uschar *s, *expciphers, *err;
2868 /* this duplicates from tls_init(), we need a better "init just global
2869 state, for no specific purpose" singleton function of our own */
2871 SSL_load_error_strings();
2872 OpenSSL_add_ssl_algorithms();
2873 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2874 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2875 list of available digests. */
2876 EVP_add_digest(EVP_sha256());
2879 if (!(tls_require_ciphers && *tls_require_ciphers))
2882 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
2884 return US"failed to expand tls_require_ciphers";
2886 if (!(expciphers && *expciphers))
2889 /* normalisation ripped from above */
2891 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2895 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
2896 if (!(ctx = SSL_CTX_new(TLS_server_method())))
2898 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
2901 ERR_error_string(ERR_get_error(), ssl_errstring);
2902 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2906 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2908 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2910 ERR_error_string(ERR_get_error(), ssl_errstring);
2911 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
2912 expciphers, ssl_errstring);
2923 /*************************************************
2924 * Report the library versions. *
2925 *************************************************/
2927 /* There have historically been some issues with binary compatibility in
2928 OpenSSL libraries; if Exim (like many other applications) is built against
2929 one version of OpenSSL but the run-time linker picks up another version,
2930 it can result in serious failures, including crashing with a SIGSEGV. So
2931 report the version found by the compiler and the run-time version.
2933 Note: some OS vendors backport security fixes without changing the version
2934 number/string, and the version date remains unchanged. The _build_ date
2935 will change, so we can more usefully assist with version diagnosis by also
2936 reporting the build date.
2938 Arguments: a FILE* to print the results to
2943 tls_version_report(FILE *f)
2945 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2948 OPENSSL_VERSION_TEXT,
2949 SSLeay_version(SSLEAY_VERSION),
2950 SSLeay_version(SSLEAY_BUILT_ON));
2951 /* third line is 38 characters for the %s and the line is 73 chars long;
2952 the OpenSSL output includes a "built on: " prefix already. */
2958 /*************************************************
2959 * Random number generation *
2960 *************************************************/
2962 /* Pseudo-random number generation. The result is not expected to be
2963 cryptographically strong but not so weak that someone will shoot themselves
2964 in the foot using it as a nonce in input in some email header scheme or
2965 whatever weirdness they'll twist this into. The result should handle fork()
2966 and avoid repeating sequences. OpenSSL handles that for us.
2970 Returns a random number in range [0, max-1]
2974 vaguely_random_number(int max)
2978 static pid_t pidlast = 0;
2981 uschar smallbuf[sizeof(r)];
2987 if (pidnow != pidlast)
2989 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2990 is unique for each thread", this doesn't apparently apply across processes,
2991 so our own warning from vaguely_random_number_fallback() applies here too.
2992 Fix per PostgreSQL. */
2998 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3002 gettimeofday(&r.tv, NULL);
3005 RAND_seed(US (&r), sizeof(r));
3007 /* We're after pseudo-random, not random; if we still don't have enough data
3008 in the internal PRNG then our options are limited. We could sleep and hope
3009 for entropy to come along (prayer technique) but if the system is so depleted
3010 in the first place then something is likely to just keep taking it. Instead,
3011 we'll just take whatever little bit of pseudo-random we can still manage to
3014 needed_len = sizeof(r);
3015 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3016 asked for a number less than 10. */
3017 for (r = max, i = 0; r; ++i)
3023 #ifdef EXIM_HAVE_RAND_PSEUDO
3024 /* We do not care if crypto-strong */
3025 i = RAND_pseudo_bytes(smallbuf, needed_len);
3027 i = RAND_bytes(smallbuf, needed_len);
3033 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3034 return vaguely_random_number_fallback(max);
3038 for (p = smallbuf; needed_len; --needed_len, ++p)
3044 /* We don't particularly care about weighted results; if someone wants
3045 smooth distribution and cares enough then they should submit a patch then. */
3052 /*************************************************
3053 * OpenSSL option parse *
3054 *************************************************/
3056 /* Parse one option for tls_openssl_options_parse below
3059 name one option name
3060 value place to store a value for it
3061 Returns success or failure in parsing
3064 struct exim_openssl_option {
3068 /* We could use a macro to expand, but we need the ifdef and not all the
3069 options document which version they were introduced in. Policylet: include
3070 all options unless explicitly for DTLS, let the administrator choose which
3073 This list is current as of:
3075 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
3077 static struct exim_openssl_option exim_openssl_options[] = {
3078 /* KEEP SORTED ALPHABETICALLY! */
3080 { US"all", SSL_OP_ALL },
3082 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
3083 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
3085 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
3086 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
3088 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
3089 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
3091 #ifdef SSL_OP_EPHEMERAL_RSA
3092 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
3094 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
3095 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
3097 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
3098 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
3100 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
3101 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
3103 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
3104 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
3106 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
3107 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
3109 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
3110 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
3112 #ifdef SSL_OP_NO_COMPRESSION
3113 { US"no_compression", SSL_OP_NO_COMPRESSION },
3115 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
3116 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
3118 #ifdef SSL_OP_NO_SSLv2
3119 { US"no_sslv2", SSL_OP_NO_SSLv2 },
3121 #ifdef SSL_OP_NO_SSLv3
3122 { US"no_sslv3", SSL_OP_NO_SSLv3 },
3124 #ifdef SSL_OP_NO_TICKET
3125 { US"no_ticket", SSL_OP_NO_TICKET },
3127 #ifdef SSL_OP_NO_TLSv1
3128 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
3130 #ifdef SSL_OP_NO_TLSv1_1
3131 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
3132 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
3133 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
3135 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
3138 #ifdef SSL_OP_NO_TLSv1_2
3139 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
3141 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
3142 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
3144 #ifdef SSL_OP_SINGLE_DH_USE
3145 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
3147 #ifdef SSL_OP_SINGLE_ECDH_USE
3148 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
3150 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
3151 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
3153 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
3154 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
3156 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
3157 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
3159 #ifdef SSL_OP_TLS_D5_BUG
3160 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
3162 #ifdef SSL_OP_TLS_ROLLBACK_BUG
3163 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
3166 static int exim_openssl_options_size =
3167 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
3171 tls_openssl_one_option_parse(uschar *name, long *value)
3174 int last = exim_openssl_options_size;
3175 while (last > first)
3177 int middle = (first + last)/2;
3178 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3181 *value = exim_openssl_options[middle].value;
3195 /*************************************************
3196 * OpenSSL option parsing logic *
3197 *************************************************/
3199 /* OpenSSL has a number of compatibility options which an administrator might
3200 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3201 we look like log_selector.
3204 option_spec the administrator-supplied string of options
3205 results ptr to long storage for the options bitmap
3206 Returns success or failure
3210 tls_openssl_options_parse(uschar *option_spec, long *results)
3215 BOOL adding, item_parsed;
3217 result = SSL_OP_NO_TICKET;
3218 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3219 * from default because it increases BEAST susceptibility. */
3220 #ifdef SSL_OP_NO_SSLv2
3221 result |= SSL_OP_NO_SSLv2;
3223 #ifdef SSL_OP_SINGLE_DH_USE
3224 result |= SSL_OP_SINGLE_DH_USE;
3233 for (s=option_spec; *s != '\0'; /**/)
3235 while (isspace(*s)) ++s;
3238 if (*s != '+' && *s != '-')
3240 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3241 "+ or - expected but found \"%s\"\n", s);
3244 adding = *s++ == '+';
3245 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3248 item_parsed = tls_openssl_one_option_parse(s, &item);
3252 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3255 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3256 adding ? "adding" : "removing", result, item, s);
3270 /* End of tls-openssl.c */