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.
123 There are two cases: with and without ServerNameIndication from the client.
124 Given TLS SNI, we can be using different keys, certs and various other
125 configuration settings, because they're re-expanded with $tls_sni set. This
126 allows vhosting with TLS. This SNI is sent in the handshake.
127 A client might not send SNI, so we need a fallback, and an initial setup too.
128 So as a server, we start out using `server_ctx`.
129 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
130 `server_sni` from `server_ctx` and then initialise settings by re-expanding
134 static SSL_CTX *client_ctx = NULL;
135 static SSL_CTX *server_ctx = NULL;
136 static SSL *client_ssl = NULL;
137 static SSL *server_ssl = NULL;
139 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
140 static SSL_CTX *server_sni = NULL;
143 static char ssl_errstring[256];
145 static int ssl_session_timeout = 200;
146 static BOOL client_verify_optional = FALSE;
147 static BOOL server_verify_optional = FALSE;
149 static BOOL reexpand_tls_files_for_sni = FALSE;
152 typedef struct tls_ext_ctx_cb {
157 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
161 uschar *file_expanded;
162 OCSP_RESPONSE *response;
165 X509_STORE *verify_store; /* non-null if status requested */
166 BOOL verify_required;
171 /* these are cached from first expand */
172 uschar *server_cipher_list;
173 /* only passed down to tls_error: */
175 const uschar * verify_cert_hostnames;
176 #ifndef DISABLE_EVENT
177 uschar * event_action;
181 /* should figure out a cleanup of API to handle state preserved per
182 implementation, for various reasons, which can be void * in the APIs.
183 For now, we hack around it. */
184 tls_ext_ctx_cb *client_static_cbinfo = NULL;
185 tls_ext_ctx_cb *server_static_cbinfo = NULL;
188 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
189 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
192 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
193 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
196 static int tls_server_stapling_cb(SSL *s, void *arg);
200 /*************************************************
202 *************************************************/
204 /* Called from lots of places when errors occur before actually starting to do
205 the TLS handshake, that is, while the session is still in clear. Always returns
206 DEFER for a server and FAIL for a client so that most calls can use "return
207 tls_error(...)" to do this processing and then give an appropriate return. A
208 single function is used for both server and client, because it is called from
209 some shared functions.
212 prefix text to include in the logged error
213 host NULL if setting up a server;
214 the connected host if setting up a client
215 msg error message or NULL if we should ask OpenSSL
216 errstr pointer to output error message
218 Returns: OK/DEFER/FAIL
222 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
226 ERR_error_string(ERR_get_error(), ssl_errstring);
227 msg = US ssl_errstring;
230 if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg);
231 return host ? FAIL : DEFER;
236 /*************************************************
237 * Callback to generate RSA key *
238 *************************************************/
242 s SSL connection (not used)
246 Returns: pointer to generated key
250 rsa_callback(SSL *s, int export, int keylength)
253 #ifdef EXIM_HAVE_RSA_GENKEY_EX
254 BIGNUM *bn = BN_new();
257 export = export; /* Shut picky compilers up */
258 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
260 #ifdef EXIM_HAVE_RSA_GENKEY_EX
261 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
262 || !(rsa_key = RSA_new())
263 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
266 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
270 ERR_error_string(ERR_get_error(), ssl_errstring);
271 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
283 x509_store_dump_cert_s_names(X509_STORE * store)
285 STACK_OF(X509_OBJECT) * roots= store->objs;
287 static uschar name[256];
289 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
291 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
292 if(tmp_obj->type == X509_LU_X509)
294 X509 * current_cert= tmp_obj->data.x509;
295 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
296 name[sizeof(name)-1] = '\0';
297 debug_printf(" %s\n", name);
305 #ifndef DISABLE_EVENT
307 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
308 BOOL *calledp, const BOOL *optionalp, const uschar * what)
314 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
317 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
318 old_cert = tlsp->peercert;
319 tlsp->peercert = X509_dup(cert);
320 /* NB we do not bother setting peerdn */
321 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
323 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
324 "depth=%d cert=%s: %s",
325 tlsp == &tls_out ? deliver_host_address : sender_host_address,
326 what, depth, dn, yield);
330 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
331 return 1; /* reject (leaving peercert set) */
333 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
334 "(host in tls_try_verify_hosts)\n");
336 X509_free(tlsp->peercert);
337 tlsp->peercert = old_cert;
343 /*************************************************
344 * Callback for verification *
345 *************************************************/
347 /* The SSL library does certificate verification if set up to do so. This
348 callback has the current yes/no state is in "state". If verification succeeded,
349 we set the certificate-verified flag. If verification failed, what happens
350 depends on whether the client is required to present a verifiable certificate
353 If verification is optional, we change the state to yes, but still log the
354 verification error. For some reason (it really would help to have proper
355 documentation of OpenSSL), this callback function then gets called again, this
356 time with state = 1. We must take care not to set the private verified flag on
357 the second time through.
359 Note: this function is not called if the client fails to present a certificate
360 when asked. We get here only if a certificate has been received. Handling of
361 optional verification for this case is done when requesting SSL to verify, by
362 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
364 May be called multiple times for different issues with a certificate, even
365 for a given "depth" in the certificate chain.
368 preverify_ok current yes/no state as 1/0
369 x509ctx certificate information.
370 tlsp per-direction (client vs. server) support data
371 calledp has-been-called flag
372 optionalp verification-is-optional flag
374 Returns: 0 if verification should fail, otherwise 1
378 verify_callback(int preverify_ok, X509_STORE_CTX *x509ctx,
379 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
381 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
382 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
385 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
386 dn[sizeof(dn)-1] = '\0';
388 if (preverify_ok == 0)
390 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
391 *verify_mode, sender_host_address)
393 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
394 tlsp == &tls_out ? deliver_host_address : sender_host_address,
396 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
401 tlsp->peercert = X509_dup(cert); /* record failing cert */
402 return 0; /* reject */
404 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
405 "tls_try_verify_hosts)\n");
410 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
412 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
413 { /* client, wanting stapling */
414 /* Add the server cert's signing chain as the one
415 for the verification of the OCSP stapled information. */
417 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
420 sk_X509_push(client_static_cbinfo->verify_stack, cert);
423 #ifndef DISABLE_EVENT
424 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
425 return 0; /* reject, with peercert set */
430 const uschar * verify_cert_hostnames;
432 if ( tlsp == &tls_out
433 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
434 /* client, wanting hostname check */
437 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
438 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
439 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
441 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
442 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
445 const uschar * list = verify_cert_hostnames;
448 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
449 if ((rc = X509_check_host(cert, CCS name, 0,
450 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
451 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
456 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
457 tlsp == &tls_out ? deliver_host_address : sender_host_address);
464 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
467 uschar * extra = verify_mode
468 ? string_sprintf(" (during %c-verify for [%s])",
469 *verify_mode, sender_host_address)
471 log_write(0, LOG_MAIN,
472 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
473 tlsp == &tls_out ? deliver_host_address : sender_host_address,
474 extra, dn, verify_cert_hostnames);
479 tlsp->peercert = X509_dup(cert); /* record failing cert */
480 return 0; /* reject */
482 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
483 "tls_try_verify_hosts)\n");
487 #ifndef DISABLE_EVENT
488 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
489 return 0; /* reject, with peercert set */
492 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
493 *calledp ? "" : " authenticated", dn);
494 if (!*calledp) tlsp->certificate_verified = TRUE;
498 return 1; /* accept, at least for this level */
502 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
504 return verify_callback(preverify_ok, x509ctx, &tls_out,
505 &client_verify_callback_called, &client_verify_optional);
509 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
511 return verify_callback(preverify_ok, x509ctx, &tls_in,
512 &server_verify_callback_called, &server_verify_optional);
518 /* This gets called *by* the dane library verify callback, which interposes
522 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
524 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
526 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
527 #ifndef DISABLE_EVENT
528 BOOL dummy_called, optional = FALSE;
531 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
532 dn[sizeof(dn)-1] = '\0';
534 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
535 preverify_ok ? "ok":"BAD", depth, dn);
537 #ifndef DISABLE_EVENT
538 if (verify_event(&tls_out, cert, depth, dn,
539 &dummy_called, &optional, US"DANE"))
540 return 0; /* reject, with peercert set */
543 if (preverify_ok == 1)
545 tls_out.dane_verified = tls_out.certificate_verified = TRUE;
547 if (client_static_cbinfo->u_ocsp.client.verify_store)
548 { /* client, wanting stapling */
549 /* Add the server cert's signing chain as the one
550 for the verification of the OCSP stapled information. */
552 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
555 sk_X509_push(client_static_cbinfo->verify_stack, cert);
561 int err = X509_STORE_CTX_get_error(x509ctx);
563 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
564 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
570 #endif /*SUPPORT_DANE*/
573 /*************************************************
574 * Information callback *
575 *************************************************/
577 /* The SSL library functions call this from time to time to indicate what they
578 are doing. We copy the string to the debugging output when TLS debugging has
590 info_callback(SSL *s, int where, int ret)
594 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
599 /*************************************************
600 * Initialize for DH *
601 *************************************************/
603 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
606 sctx The current SSL CTX (inbound or outbound)
607 dhparam DH parameter file or fixed parameter identity string
608 host connected host, if client; NULL if server
609 errstr error string pointer
611 Returns: TRUE if OK (nothing to set up, or setup worked)
615 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
623 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
626 if (!dhexpanded || !*dhexpanded)
627 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
628 else if (dhexpanded[0] == '/')
630 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
632 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
633 host, US strerror(errno), errstr);
639 if (Ustrcmp(dhexpanded, "none") == 0)
641 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
645 if (!(pem = std_dh_prime_named(dhexpanded)))
647 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
648 host, US strerror(errno), errstr);
651 bio = BIO_new_mem_buf(CS pem, -1);
654 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
657 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
662 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
663 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
664 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
665 * If someone wants to dance at the edge, then they can raise the limit or use
666 * current libraries. */
667 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
668 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
669 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
670 dh_bitsize = DH_bits(dh);
672 dh_bitsize = 8 * DH_size(dh);
675 /* Even if it is larger, we silently return success rather than cause things
676 * to fail out, so that a too-large DH will not knock out all TLS; it's a
677 * debatable choice. */
678 if (dh_bitsize > tls_dh_max_bits)
681 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
682 dh_bitsize, tls_dh_max_bits);
686 SSL_CTX_set_tmp_dh(sctx, dh);
688 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
689 dhexpanded ? dhexpanded : US"default", dh_bitsize);
701 /*************************************************
702 * Initialize for ECDH *
703 *************************************************/
705 /* Load parameters for ECDH encryption.
707 For now, we stick to NIST P-256 because: it's simple and easy to configure;
708 it avoids any patent issues that might bite redistributors; despite events in
709 the news and concerns over curve choices, we're not cryptographers, we're not
710 pretending to be, and this is "good enough" to be better than no support,
711 protecting against most adversaries. Given another year or two, there might
712 be sufficient clarity about a "right" way forward to let us make an informed
713 decision, instead of a knee-jerk reaction.
715 Longer-term, we should look at supporting both various named curves and
716 external files generated with "openssl ecparam", much as we do for init_dh().
717 We should also support "none" as a value, to explicitly avoid initialisation.
722 sctx The current SSL CTX (inbound or outbound)
723 host connected host, if client; NULL if server
724 errstr error string pointer
726 Returns: TRUE if OK (nothing to set up, or setup worked)
730 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
732 #ifdef OPENSSL_NO_ECDH
741 if (host) /* No ECDH setup for clients, only for servers */
744 # ifndef EXIM_HAVE_ECDH
746 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
750 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
752 if (!exp_curve || !*exp_curve)
755 /* "auto" needs to be handled carefully.
756 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
757 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
758 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
759 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
760 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
762 if (Ustrcmp(exp_curve, "auto") == 0)
764 #if OPENSSL_VERSION_NUMBER < 0x10002000L
765 DEBUG(D_tls) debug_printf(
766 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
767 exp_curve = US"prime256v1";
769 # if defined SSL_CTRL_SET_ECDH_AUTO
770 DEBUG(D_tls) debug_printf(
771 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
772 SSL_CTX_set_ecdh_auto(sctx, 1);
775 DEBUG(D_tls) debug_printf(
776 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
782 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
783 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
784 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
785 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
789 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
794 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
796 tls_error(US"Unable to create ec curve", host, NULL, errstr);
800 /* The "tmp" in the name here refers to setting a temporary key
801 not to the stability of the interface. */
803 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
804 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
806 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
811 # endif /*EXIM_HAVE_ECDH*/
812 #endif /*OPENSSL_NO_ECDH*/
819 /*************************************************
820 * Load OCSP information into state *
821 *************************************************/
822 /* Called to load the server OCSP response from the given file into memory, once
823 caller has determined this is needed. Checks validity. Debugs a message
826 ASSUMES: single response, for single cert.
829 sctx the SSL_CTX* to update
830 cbinfo various parts of session state
831 expanded the filename putatively holding an OCSP response
836 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
839 OCSP_RESPONSE * resp;
840 OCSP_BASICRESP * basic_response;
841 OCSP_SINGLERESP * single_response;
842 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
844 unsigned long verify_flags;
845 int status, reason, i;
847 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
848 if (cbinfo->u_ocsp.server.response)
850 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
851 cbinfo->u_ocsp.server.response = NULL;
854 if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
856 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
857 cbinfo->u_ocsp.server.file_expanded);
861 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
865 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
869 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
871 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
872 OCSP_response_status_str(status), status);
876 if (!(basic_response = OCSP_response_get1_basic(resp)))
879 debug_printf("OCSP response parse error: unable to extract basic response.\n");
883 sk = cbinfo->verify_stack;
884 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
886 /* May need to expose ability to adjust those flags?
887 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
888 OCSP_TRUSTOTHER OCSP_NOINTERN */
890 /* This does a full verify on the OCSP proof before we load it for serving
891 up; possibly overkill - just date-checks might be nice enough.
893 OCSP_basic_verify takes a "store" arg, but does not
894 use it for the chain verification, which is all we do
895 when OCSP_NOVERIFY is set. The content from the wire
896 "basic_response" and a cert-stack "sk" are all that is used.
898 We have a stack, loaded in setup_certs() if tls_verify_certificates
899 was a file (not a directory, or "system"). It is unfortunate we
900 cannot used the connection context store, as that would neatly
901 handle the "system" case too, but there seems to be no library
902 function for getting a stack from a store.
903 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
904 We do not free the stack since it could be needed a second time for
907 Separately we might try to replace using OCSP_basic_verify() - which seems to not
908 be a public interface into the OpenSSL library (there's no manual entry) -
909 But what with? We also use OCSP_basic_verify in the client stapling callback.
910 And there we NEED it; we must verify that status... unless the
911 library does it for us anyway? */
913 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
917 ERR_error_string(ERR_get_error(), ssl_errstring);
918 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
923 /* Here's the simplifying assumption: there's only one response, for the
924 one certificate we use, and nothing for anything else in a chain. If this
925 proves false, we need to extract a cert id from our issued cert
926 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
927 right cert in the stack and then calls OCSP_single_get0_status()).
929 I'm hoping to avoid reworking a bunch more of how we handle state here. */
931 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
934 debug_printf("Unable to get first response from OCSP basic response.\n");
938 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
939 if (status != V_OCSP_CERTSTATUS_GOOD)
941 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
942 OCSP_cert_status_str(status), status,
943 OCSP_crl_reason_str(reason), reason);
947 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
949 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
954 cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/
958 if (running_in_test_harness)
960 extern char ** environ;
962 if (environ) for (p = USS environ; *p; p++)
963 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
965 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
966 goto supply_response;
971 #endif /*!DISABLE_OCSP*/
976 /* Create and install a selfsigned certificate, for use in server mode */
979 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
987 where = US"allocating pkey";
988 if (!(pkey = EVP_PKEY_new()))
991 where = US"allocating cert";
992 if (!(x509 = X509_new()))
995 where = US"generating pkey";
996 if (!(rsa = rsa_callback(NULL, 0, 1024)))
999 where = US"assigning pkey";
1000 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1003 X509_set_version(x509, 2); /* N+1 - version 3 */
1004 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1005 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1006 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1007 X509_set_pubkey(x509, pkey);
1009 name = X509_get_subject_name(x509);
1010 X509_NAME_add_entry_by_txt(name, "C",
1011 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1012 X509_NAME_add_entry_by_txt(name, "O",
1013 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1014 X509_NAME_add_entry_by_txt(name, "CN",
1015 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1016 X509_set_issuer_name(x509, name);
1018 where = US"signing cert";
1019 if (!X509_sign(x509, pkey, EVP_md5()))
1022 where = US"installing selfsign cert";
1023 if (!SSL_CTX_use_certificate(sctx, x509))
1026 where = US"installing selfsign key";
1027 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1033 (void) tls_error(where, NULL, NULL, errstr);
1034 if (x509) X509_free(x509);
1035 if (pkey) EVP_PKEY_free(pkey);
1043 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1046 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file);
1047 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1048 return tls_error(string_sprintf(
1049 "SSL_CTX_use_certificate_chain_file file=%s", file),
1050 cbinfo->host, NULL, errstr);
1055 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1058 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file);
1059 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1060 return tls_error(string_sprintf(
1061 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1066 /*************************************************
1067 * Expand key and cert file specs *
1068 *************************************************/
1070 /* Called once during tls_init and possibly again during TLS setup, for a
1071 new context, if Server Name Indication was used and tls_sni was seen in
1072 the certificate string.
1075 sctx the SSL_CTX* to update
1076 cbinfo various parts of session state
1077 errstr error string pointer
1079 Returns: OK/DEFER/FAIL
1083 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1088 if (!cbinfo->certificate)
1090 if (!cbinfo->is_server) /* client */
1093 if (tls_install_selfsign(sctx, errstr) != OK)
1100 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1101 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1102 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1104 reexpand_tls_files_for_sni = TRUE;
1106 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1110 if (cbinfo->is_server)
1112 const uschar * file_list = expanded;
1116 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1117 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1120 else /* would there ever be a need for multiple client certs? */
1121 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1124 if (cbinfo->privatekey != NULL &&
1125 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1128 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1129 of the expansion is an empty string, ignore it also, and assume the private
1130 key is in the same file as the certificate. */
1132 if (expanded && *expanded)
1133 if (cbinfo->is_server)
1135 const uschar * file_list = expanded;
1139 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1140 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1143 else /* would there ever be a need for multiple client certs? */
1144 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1148 #ifndef DISABLE_OCSP
1149 if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
1152 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
1155 if (expanded && *expanded)
1157 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
1158 if ( cbinfo->u_ocsp.server.file_expanded
1159 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
1161 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1164 ocsp_load_response(sctx, cbinfo, expanded);
1175 /*************************************************
1176 * Callback to handle SNI *
1177 *************************************************/
1179 /* Called when acting as server during the TLS session setup if a Server Name
1180 Indication extension was sent by the client.
1182 API documentation is OpenSSL s_server.c implementation.
1185 s SSL* of the current session
1186 ad unknown (part of OpenSSL API) (unused)
1187 arg Callback of "our" registered data
1189 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1192 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1194 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1196 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1197 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1199 int old_pool = store_pool;
1200 uschar * dummy_errstr;
1203 return SSL_TLSEXT_ERR_OK;
1205 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1206 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1208 /* Make the extension value available for expansion */
1209 store_pool = POOL_PERM;
1210 tls_in.sni = string_copy(US servername);
1211 store_pool = old_pool;
1213 if (!reexpand_tls_files_for_sni)
1214 return SSL_TLSEXT_ERR_OK;
1216 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1217 not confident that memcpy wouldn't break some internal reference counting.
1218 Especially since there's a references struct member, which would be off. */
1220 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1221 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1223 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1226 ERR_error_string(ERR_get_error(), ssl_errstring);
1227 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1228 return SSL_TLSEXT_ERR_NOACK;
1231 /* Not sure how many of these are actually needed, since SSL object
1232 already exists. Might even need this selfsame callback, for reneg? */
1234 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1235 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1236 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1237 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1238 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1239 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1241 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1242 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1244 return SSL_TLSEXT_ERR_NOACK;
1246 if (cbinfo->server_cipher_list)
1247 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
1248 #ifndef DISABLE_OCSP
1249 if (cbinfo->u_ocsp.server.file)
1251 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1252 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1256 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1257 verify_callback_server, &dummy_errstr)) != OK)
1258 return SSL_TLSEXT_ERR_NOACK;
1260 /* do this after setup_certs, because this can require the certs for verifying
1261 OCSP information. */
1262 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1263 return SSL_TLSEXT_ERR_NOACK;
1265 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1266 SSL_set_SSL_CTX(s, server_sni);
1268 return SSL_TLSEXT_ERR_OK;
1270 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1275 #ifndef DISABLE_OCSP
1277 /*************************************************
1278 * Callback to handle OCSP Stapling *
1279 *************************************************/
1281 /* Called when acting as server during the TLS session setup if the client
1282 requests OCSP information with a Certificate Status Request.
1284 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1290 tls_server_stapling_cb(SSL *s, void *arg)
1292 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1293 uschar *response_der; /*XXX blob */
1294 int response_der_len;
1296 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1297 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1298 buggy in current OpenSSL; it returns the last cert loaded always rather than
1299 the one actually presented. So we can't support a stack of OCSP proofs at
1303 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1304 cbinfo->u_ocsp.server.response ? "have" : "lack");
1306 tls_in.ocsp = OCSP_NOT_RESP;
1307 if (!cbinfo->u_ocsp.server.response)
1308 return SSL_TLSEXT_ERR_NOACK;
1310 response_der = NULL;
1311 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1313 if (response_der_len <= 0)
1314 return SSL_TLSEXT_ERR_NOACK;
1316 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1317 tls_in.ocsp = OCSP_VFIED;
1318 return SSL_TLSEXT_ERR_OK;
1323 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1325 BIO_printf(bp, "\t%s: ", str);
1326 ASN1_GENERALIZEDTIME_print(bp, time);
1331 tls_client_stapling_cb(SSL *s, void *arg)
1333 tls_ext_ctx_cb * cbinfo = arg;
1334 const unsigned char * p;
1336 OCSP_RESPONSE * rsp;
1337 OCSP_BASICRESP * bs;
1340 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1341 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1344 /* Expect this when we requested ocsp but got none */
1345 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1346 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1348 DEBUG(D_tls) debug_printf(" null\n");
1349 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1352 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1354 tls_out.ocsp = OCSP_FAILED;
1355 if (LOGGING(tls_cipher))
1356 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1358 DEBUG(D_tls) debug_printf(" parse error\n");
1362 if(!(bs = OCSP_response_get1_basic(rsp)))
1364 tls_out.ocsp = OCSP_FAILED;
1365 if (LOGGING(tls_cipher))
1366 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1368 DEBUG(D_tls) debug_printf(" error parsing response\n");
1369 OCSP_RESPONSE_free(rsp);
1373 /* We'd check the nonce here if we'd put one in the request. */
1374 /* However that would defeat cacheability on the server so we don't. */
1376 /* This section of code reworked from OpenSSL apps source;
1377 The OpenSSL Project retains copyright:
1378 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1383 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1385 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1387 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1389 /* Use the chain that verified the server cert to verify the stapled info */
1390 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1392 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1393 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1395 tls_out.ocsp = OCSP_FAILED;
1396 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1397 "Received TLS cert status response, itself unverifiable: %s",
1398 ERR_reason_error_string(ERR_peek_error()));
1399 BIO_printf(bp, "OCSP response verify failure\n");
1400 ERR_print_errors(bp);
1401 OCSP_RESPONSE_print(bp, rsp, 0);
1405 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1407 /*XXX So we have a good stapled OCSP status. How do we know
1408 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1409 OCSP_resp_find_status() which matches on a cert id, which presumably
1410 we should use. Making an id needs OCSP_cert_id_new(), which takes
1411 issuerName, issuerKey, serialNumber. Are they all in the cert?
1413 For now, carry on blindly accepting the resp. */
1416 OCSP_SINGLERESP * single;
1418 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1419 if (OCSP_resp_count(bs) != 1)
1421 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1422 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1425 tls_out.ocsp = OCSP_FAILED;
1426 log_write(0, LOG_MAIN, "OCSP stapling "
1427 "with multiple responses not handled");
1430 single = OCSP_resp_get0(bs, 0);
1431 status = OCSP_single_get0_status(single, &reason, &rev,
1432 &thisupd, &nextupd);
1435 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1436 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1437 if (!OCSP_check_validity(thisupd, nextupd,
1438 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1440 tls_out.ocsp = OCSP_FAILED;
1441 DEBUG(D_tls) ERR_print_errors(bp);
1442 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1446 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1447 OCSP_cert_status_str(status));
1450 case V_OCSP_CERTSTATUS_GOOD:
1451 tls_out.ocsp = OCSP_VFIED;
1454 case V_OCSP_CERTSTATUS_REVOKED:
1455 tls_out.ocsp = OCSP_FAILED;
1456 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1457 reason != -1 ? "; reason: " : "",
1458 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1459 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1462 tls_out.ocsp = OCSP_FAILED;
1463 log_write(0, LOG_MAIN,
1464 "Server certificate status unknown, in OCSP stapling");
1469 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1474 OCSP_RESPONSE_free(rsp);
1477 #endif /*!DISABLE_OCSP*/
1480 /*************************************************
1481 * Initialize for TLS *
1482 *************************************************/
1484 /* Called from both server and client code, to do preliminary initialization
1485 of the library. We allocate and return a context structure.
1488 ctxp returned SSL context
1489 host connected host, if client; NULL if server
1490 dhparam DH parameter file
1491 certificate certificate file
1492 privatekey private key
1493 ocsp_file file of stapling info (server); flag for require ocsp (client)
1494 addr address if client; NULL if server (for some randomness)
1495 cbp place to put allocated callback context
1496 errstr error string pointer
1498 Returns: OK/DEFER/FAIL
1502 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1504 #ifndef DISABLE_OCSP
1505 uschar *ocsp_file, /*XXX stack, in server*/
1507 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
1512 tls_ext_ctx_cb * cbinfo;
1514 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1515 cbinfo->certificate = certificate;
1516 cbinfo->privatekey = privatekey;
1517 cbinfo->is_server = host==NULL;
1518 #ifndef DISABLE_OCSP
1519 cbinfo->verify_stack = NULL;
1522 cbinfo->u_ocsp.server.file = ocsp_file;
1523 cbinfo->u_ocsp.server.file_expanded = NULL;
1524 cbinfo->u_ocsp.server.response = NULL;
1527 cbinfo->u_ocsp.client.verify_store = NULL;
1529 cbinfo->dhparam = dhparam;
1530 cbinfo->server_cipher_list = NULL;
1531 cbinfo->host = host;
1532 #ifndef DISABLE_EVENT
1533 cbinfo->event_action = NULL;
1536 SSL_load_error_strings(); /* basic set up */
1537 OpenSSL_add_ssl_algorithms();
1539 #ifdef EXIM_HAVE_SHA256
1540 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1541 list of available digests. */
1542 EVP_add_digest(EVP_sha256());
1545 /* Create a context.
1546 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1547 negotiation in the different methods; as far as I can tell, the only
1548 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1549 when OpenSSL is built without SSLv2 support.
1550 By disabling with openssl_options, we can let admins re-enable with the
1553 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1554 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1556 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1558 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1560 /* It turns out that we need to seed the random number generator this early in
1561 order to get the full complement of ciphers to work. It took me roughly a day
1562 of work to discover this by experiment.
1564 On systems that have /dev/urandom, SSL may automatically seed itself from
1565 there. Otherwise, we have to make something up as best we can. Double check
1571 gettimeofday(&r.tv, NULL);
1574 RAND_seed(US (&r), sizeof(r));
1575 RAND_seed(US big_buffer, big_buffer_size);
1576 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1579 return tls_error(US"RAND_status", host,
1580 US"unable to seed random number generator", errstr);
1583 /* Set up the information callback, which outputs if debugging is at a suitable
1586 DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1588 /* Automatically re-try reads/writes after renegotiation. */
1589 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1591 /* Apply administrator-supplied work-arounds.
1592 Historically we applied just one requested option,
1593 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1594 moved to an administrator-controlled list of options to specify and
1595 grandfathered in the first one as the default value for "openssl_options".
1597 No OpenSSL version number checks: the options we accept depend upon the
1598 availability of the option value macros from OpenSSL. */
1600 if (!tls_openssl_options_parse(openssl_options, &init_options))
1601 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1605 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1606 if (!(SSL_CTX_set_options(ctx, init_options)))
1607 return tls_error(string_sprintf(
1608 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
1611 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1613 /* We'd like to disable session cache unconditionally, but foolish Outlook
1614 Express clients then give up the first TLS connection and make a second one
1615 (which works). Only when there is an IMAP service on the same machine.
1616 Presumably OE is trying to use the cache for A on B. Leave it enabled for
1617 now, until we work out a decent way of presenting control to the config. It
1618 will never be used because we use a new context every time. */
1620 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
1623 /* Initialize with DH parameters if supplied */
1624 /* Initialize ECDH temp key parameter selection */
1626 if ( !init_dh(ctx, dhparam, host, errstr)
1627 || !init_ecdh(ctx, host, errstr)
1631 /* Set up certificate and key (and perhaps OCSP info) */
1633 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
1636 /* If we need to handle SNI or OCSP, do so */
1638 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1639 # ifndef DISABLE_OCSP
1640 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1642 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1647 if (!host) /* server */
1649 # ifndef DISABLE_OCSP
1650 /* We check u_ocsp.server.file, not server.response, because we care about if
1651 the option exists, not what the current expansion might be, as SNI might
1652 change the certificate and OCSP file in use between now and the time the
1653 callback is invoked. */
1654 if (cbinfo->u_ocsp.server.file)
1656 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
1657 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1660 /* We always do this, so that $tls_sni is available even if not used in
1662 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
1663 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
1665 # ifndef DISABLE_OCSP
1667 if(ocsp_file) /* wanting stapling */
1669 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1671 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1674 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
1675 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1680 cbinfo->verify_cert_hostnames = NULL;
1682 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1683 /* Set up the RSA callback */
1684 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
1687 /* Finally, set the timeout, and we are done */
1689 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
1690 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1701 /*************************************************
1702 * Get name of cipher in use *
1703 *************************************************/
1706 Argument: pointer to an SSL structure for the connection
1707 buffer to use for answer
1709 pointer to number of bits for cipher
1714 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1716 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
1717 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1718 the accessor functions use const in the prototype. */
1720 const uschar * ver = CUS SSL_get_version(ssl);
1721 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1723 SSL_CIPHER_get_bits(c, bits);
1725 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1726 SSL_CIPHER_get_name(c), *bits);
1728 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1733 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1735 /*XXX we might consider a list-of-certs variable for the cert chain.
1736 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1737 in list-handling functions, also consider the difference between the entire
1738 chain and the elements sent by the peer. */
1740 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1741 if (!tlsp->peercert)
1742 tlsp->peercert = SSL_get_peer_certificate(ssl);
1743 /* Beware anonymous ciphers which lead to server_cert being NULL */
1746 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1747 peerdn[bsize-1] = '\0';
1748 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1751 tlsp->peerdn = NULL;
1758 /*************************************************
1759 * Set up for verifying certificates *
1760 *************************************************/
1762 #ifndef DISABLE_OCSP
1763 /* Load certs from file, return TRUE on success */
1766 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1771 while (sk_X509_num(verify_stack) > 0)
1772 X509_free(sk_X509_pop(verify_stack));
1774 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1775 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1776 sk_X509_push(verify_stack, x);
1784 /* Called by both client and server startup; on the server possibly
1785 repeated after a Server Name Indication.
1788 sctx SSL_CTX* to initialise
1789 certs certs file or NULL
1790 crl CRL file or NULL
1791 host NULL in a server; the remote host in a client
1792 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1793 otherwise passed as FALSE
1794 cert_vfy_cb Callback function for certificate verification
1795 errstr error string pointer
1797 Returns: OK/DEFER/FAIL
1801 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1802 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
1804 uschar *expcerts, *expcrl;
1806 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
1808 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
1810 if (expcerts && *expcerts)
1812 /* Tell the library to use its compiled-in location for the system default
1813 CA bundle. Then add the ones specified in the config, if any. */
1815 if (!SSL_CTX_set_default_verify_paths(sctx))
1816 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
1818 if (Ustrcmp(expcerts, "system") != 0)
1820 struct stat statbuf;
1822 if (Ustat(expcerts, &statbuf) < 0)
1824 log_write(0, LOG_MAIN|LOG_PANIC,
1825 "failed to stat %s for certificates", expcerts);
1831 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1832 { file = NULL; dir = expcerts; }
1835 file = expcerts; dir = NULL;
1836 #ifndef DISABLE_OCSP
1837 /* In the server if we will be offering an OCSP proof, load chain from
1838 file for verifying the OCSP proof at load time. */
1841 && statbuf.st_size > 0
1842 && server_static_cbinfo->u_ocsp.server.file
1843 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
1846 log_write(0, LOG_MAIN|LOG_PANIC,
1847 "failed to load cert chain from %s", file);
1853 /* If a certificate file is empty, the next function fails with an
1854 unhelpful error message. If we skip it, we get the correct behaviour (no
1855 certificates are recognized, but the error message is still misleading (it
1856 says no certificate was supplied). But this is better. */
1858 if ( (!file || statbuf.st_size > 0)
1859 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1860 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
1862 /* Load the list of CAs for which we will accept certs, for sending
1863 to the client. This is only for the one-file tls_verify_certificates
1865 If a list isn't loaded into the server, but
1866 some verify locations are set, the server end appears to make
1867 a wildcard request for client certs.
1868 Meanwhile, the client library as default behaviour *ignores* the list
1869 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1870 Because of this, and that the dir variant is likely only used for
1871 the public-CA bundle (not for a private CA), not worth fixing.
1875 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1877 SSL_CTX_set_client_CA_list(sctx, names);
1878 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1879 sk_X509_NAME_num(names));
1884 /* Handle a certificate revocation list. */
1886 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1888 /* This bit of code is now the version supplied by Lars Mainka. (I have
1889 merely reformatted it into the Exim code style.)
1891 "From here I changed the code to add support for multiple crl's
1892 in pem format in one file or to support hashed directory entries in
1893 pem format instead of a file. This method now uses the library function
1894 X509_STORE_load_locations to add the CRL location to the SSL context.
1895 OpenSSL will then handle the verify against CA certs and CRLs by
1896 itself in the verify callback." */
1898 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
1899 if (expcrl && *expcrl)
1901 struct stat statbufcrl;
1902 if (Ustat(expcrl, &statbufcrl) < 0)
1904 log_write(0, LOG_MAIN|LOG_PANIC,
1905 "failed to stat %s for certificates revocation lists", expcrl);
1910 /* is it a file or directory? */
1912 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1913 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1917 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1923 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1925 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1926 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
1928 /* setting the flags to check against the complete crl chain */
1930 X509_STORE_set_flags(cvstore,
1931 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1935 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1937 /* If verification is optional, don't fail if no certificate */
1939 SSL_CTX_set_verify(sctx,
1940 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1949 /*************************************************
1950 * Start a TLS session in a server *
1951 *************************************************/
1953 /* This is called when Exim is running as a server, after having received
1954 the STARTTLS command. It must respond to that command, and then negotiate
1958 require_ciphers allowed ciphers
1959 errstr pointer to error message
1961 Returns: OK on success
1962 DEFER for errors before the start of the negotiation
1963 FAIL for errors during the negotiation; the server can't
1968 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
1971 uschar * expciphers;
1972 tls_ext_ctx_cb * cbinfo;
1973 static uschar peerdn[256];
1974 static uschar cipherbuf[256];
1976 /* Check for previous activation */
1978 if (tls_in.active >= 0)
1980 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
1981 smtp_printf("554 Already in TLS\r\n", FALSE);
1985 /* Initialize the SSL library. If it fails, it will already have logged
1988 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1989 #ifndef DISABLE_OCSP
1990 tls_ocsp_file, /*XXX stack*/
1992 NULL, &server_static_cbinfo, errstr);
1993 if (rc != OK) return rc;
1994 cbinfo = server_static_cbinfo;
1996 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
1999 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2000 were historically separated by underscores. So that I can use either form in my
2001 tests, and also for general convenience, we turn underscores into hyphens here.
2006 uschar * s = expciphers;
2007 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2008 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2009 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2010 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2011 cbinfo->server_cipher_list = expciphers;
2014 /* If this is a host for which certificate verification is mandatory or
2015 optional, set up appropriately. */
2017 tls_in.certificate_verified = FALSE;
2019 tls_in.dane_verified = FALSE;
2021 server_verify_callback_called = FALSE;
2023 if (verify_check_host(&tls_verify_hosts) == OK)
2025 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2026 FALSE, verify_callback_server, errstr);
2027 if (rc != OK) return rc;
2028 server_verify_optional = FALSE;
2030 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2032 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2033 TRUE, verify_callback_server, errstr);
2034 if (rc != OK) return rc;
2035 server_verify_optional = TRUE;
2038 /* Prepare for new connection */
2040 if (!(server_ssl = SSL_new(server_ctx)))
2041 return tls_error(US"SSL_new", NULL, NULL, errstr);
2043 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2045 * With the SSL_clear(), we get strange interoperability bugs with
2046 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2047 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2049 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2050 * session shutdown. In this case, we have a brand new object and there's no
2051 * obvious reason to immediately clear it. I'm guessing that this was
2052 * originally added because of incomplete initialisation which the clear fixed,
2053 * in some historic release.
2056 /* Set context and tell client to go ahead, except in the case of TLS startup
2057 on connection, where outputting anything now upsets the clients and tends to
2058 make them disconnect. We need to have an explicit fflush() here, to force out
2059 the response. Other smtp_printf() calls do not need it, because in non-TLS
2060 mode, the fflush() happens when smtp_getc() is called. */
2062 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2063 if (!tls_in.on_connect)
2065 smtp_printf("220 TLS go ahead\r\n", FALSE);
2069 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2070 that the OpenSSL library doesn't. */
2072 SSL_set_wfd(server_ssl, fileno(smtp_out));
2073 SSL_set_rfd(server_ssl, fileno(smtp_in));
2074 SSL_set_accept_state(server_ssl);
2076 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2078 sigalrm_seen = FALSE;
2079 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2080 rc = SSL_accept(server_ssl);
2085 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2089 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2091 /* TLS has been set up. Adjust the input functions to read via TLS,
2092 and initialize things. */
2094 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2096 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
2097 tls_in.cipher = cipherbuf;
2102 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
2103 debug_printf("Shared ciphers: %s\n", buf);
2106 /* Record the certificate we presented */
2108 X509 * crt = SSL_get_certificate(server_ssl);
2109 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2112 /* Only used by the server-side tls (tls_in), including tls_getc.
2113 Client-side (tls_out) reads (seem to?) go via
2114 smtp_read_response()/ip_recv().
2115 Hence no need to duplicate for _in and _out.
2117 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2118 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2119 ssl_xfer_eof = ssl_xfer_error = FALSE;
2121 receive_getc = tls_getc;
2122 receive_getbuf = tls_getbuf;
2123 receive_get_cache = tls_get_cache;
2124 receive_ungetc = tls_ungetc;
2125 receive_feof = tls_feof;
2126 receive_ferror = tls_ferror;
2127 receive_smtp_buffered = tls_smtp_buffered;
2129 tls_in.active = fileno(smtp_out);
2137 tls_client_basic_ctx_init(SSL_CTX * ctx,
2138 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2142 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2143 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2144 the specified host patterns if one of them is defined */
2146 if ( ( !ob->tls_verify_hosts
2147 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2149 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
2151 client_verify_optional = FALSE;
2152 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
2153 client_verify_optional = TRUE;
2157 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2158 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2162 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
2164 cbinfo->verify_cert_hostnames =
2166 string_domain_utf8_to_alabel(host->name, NULL);
2170 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2171 cbinfo->verify_cert_hostnames);
2179 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2183 const char * hostnames[2] = { CS host->name, NULL };
2186 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2187 return tls_error(US"hostnames load", host, NULL, errstr);
2189 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2191 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2192 ) if (rr->type == T_TLSA)
2194 const uschar * p = rr->data;
2195 uint8_t usage, selector, mtype;
2196 const char * mdname;
2200 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2201 if (usage != 2 && usage != 3) continue;
2208 default: continue; /* Only match-types 0, 1, 2 are supported */
2209 case 0: mdname = NULL; break;
2210 case 1: mdname = "sha256"; break;
2211 case 2: mdname = "sha512"; break;
2215 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2218 return tls_error(US"tlsa load", host, NULL, errstr);
2219 case 0: /* action not taken */
2223 tls_out.tlsa_usage |= 1<<usage;
2229 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2232 #endif /*SUPPORT_DANE*/
2236 /*************************************************
2237 * Start a TLS session in a client *
2238 *************************************************/
2240 /* Called from the smtp transport after STARTTLS has been accepted.
2243 fd the fd of the connection
2244 host connected host (for messages)
2245 addr the first address
2246 tb transport (always smtp)
2247 tlsa_dnsa tlsa lookup, if DANE, else null
2248 errstr error string pointer
2250 Returns: OK on success
2251 FAIL otherwise - note that tls_error() will not give DEFER
2252 because this is not a server
2256 tls_client_start(int fd, host_item *host, address_item *addr,
2257 transport_instance * tb,
2259 dns_answer * tlsa_dnsa,
2263 smtp_transport_options_block * ob =
2264 (smtp_transport_options_block *)tb->options_block;
2265 static uschar peerdn[256];
2266 uschar * expciphers;
2268 static uschar cipherbuf[256];
2270 #ifndef DISABLE_OCSP
2271 BOOL request_ocsp = FALSE;
2272 BOOL require_ocsp = FALSE;
2276 tls_out.tlsa_usage = 0;
2279 #ifndef DISABLE_OCSP
2281 # ifdef SUPPORT_DANE
2283 && ob->hosts_request_ocsp[0] == '*'
2284 && ob->hosts_request_ocsp[1] == '\0'
2287 /* Unchanged from default. Use a safer one under DANE */
2288 request_ocsp = TRUE;
2289 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2290 " {= {4}{$tls_out_tlsa_usage}} } "
2296 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
2297 request_ocsp = TRUE;
2299 # ifdef SUPPORT_DANE
2303 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2307 rc = tls_init(&client_ctx, host, NULL,
2308 ob->tls_certificate, ob->tls_privatekey,
2309 #ifndef DISABLE_OCSP
2310 (void *)(long)request_ocsp,
2312 addr, &client_static_cbinfo, errstr);
2313 if (rc != OK) return rc;
2315 tls_out.certificate_verified = FALSE;
2316 client_verify_callback_called = FALSE;
2322 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2323 other failures should be treated as problems. */
2324 if (ob->dane_require_tls_ciphers &&
2325 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2326 &expciphers, errstr))
2328 if (expciphers && *expciphers == '\0')
2333 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2334 &expciphers, errstr))
2337 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2338 are separated by underscores. So that I can use either form in my tests, and
2339 also for general convenience, we turn underscores into hyphens here. */
2343 uschar *s = expciphers;
2344 while (*s) { if (*s == '_') *s = '-'; s++; }
2345 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2346 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
2347 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2353 SSL_CTX_set_verify(client_ctx,
2354 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2355 verify_callback_client_dane);
2357 if (!DANESSL_library_init())
2358 return tls_error(US"library init", host, NULL, errstr);
2359 if (DANESSL_CTX_init(client_ctx) <= 0)
2360 return tls_error(US"context init", host, NULL, errstr);
2366 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob,
2367 client_static_cbinfo, errstr)) != OK)
2370 if (!(client_ssl = SSL_new(client_ctx)))
2371 return tls_error(US"SSL_new", host, NULL, errstr);
2372 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
2373 SSL_set_fd(client_ssl, fd);
2374 SSL_set_connect_state(client_ssl);
2378 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni, errstr))
2382 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2384 else if (!Ustrlen(tls_out.sni))
2388 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2389 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
2390 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
2392 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2400 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa, errstr)) != OK)
2404 #ifndef DISABLE_OCSP
2405 /* Request certificate status at connection-time. If the server
2406 does OCSP stapling we will get the callback (set in tls_init()) */
2407 # ifdef SUPPORT_DANE
2411 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2412 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2414 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2415 this means we avoid the OCSP request, we wasted the setup
2416 cost in tls_init(). */
2417 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2418 request_ocsp = require_ocsp
2419 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2426 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
2427 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2428 tls_out.ocsp = OCSP_NOT_RESP;
2432 #ifndef DISABLE_EVENT
2433 client_static_cbinfo->event_action = tb->event_action;
2436 /* There doesn't seem to be a built-in timeout on connection. */
2438 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2439 sigalrm_seen = FALSE;
2440 alarm(ob->command_timeout);
2441 rc = SSL_connect(client_ssl);
2446 DANESSL_cleanup(client_ssl);
2450 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL,
2453 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2455 peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
2457 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2458 tls_out.cipher = cipherbuf;
2460 /* Record the certificate we presented */
2462 X509 * crt = SSL_get_certificate(client_ssl);
2463 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2466 tls_out.active = fd;
2475 tls_refill(unsigned lim)
2480 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2481 ssl_xfer_buffer, ssl_xfer_buffer_size);
2483 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2484 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2485 MIN(ssl_xfer_buffer_size, lim));
2486 error = SSL_get_error(server_ssl, inbytes);
2487 if (smtp_receive_timeout > 0) alarm(0);
2489 if (had_command_timeout) /* set by signal handler */
2490 smtp_command_timeout_exit(); /* does not return */
2491 if (had_command_sigterm)
2492 smtp_command_sigterm_exit();
2493 if (had_data_timeout)
2494 smtp_data_timeout_exit();
2495 if (had_data_sigint)
2496 smtp_data_sigint_exit();
2498 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2499 closed down, not that the socket itself has been closed down. Revert to
2500 non-SSL handling. */
2502 if (error == SSL_ERROR_ZERO_RETURN)
2504 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2506 receive_getc = smtp_getc;
2507 receive_getbuf = smtp_getbuf;
2508 receive_get_cache = smtp_get_cache;
2509 receive_ungetc = smtp_ungetc;
2510 receive_feof = smtp_feof;
2511 receive_ferror = smtp_ferror;
2512 receive_smtp_buffered = smtp_buffered;
2514 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2515 SSL_shutdown(server_ssl);
2517 #ifndef DISABLE_OCSP
2518 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2519 server_static_cbinfo->verify_stack = NULL;
2521 SSL_free(server_ssl);
2522 SSL_CTX_free(server_ctx);
2527 tls_in.cipher = NULL;
2528 tls_in.peerdn = NULL;
2534 /* Handle genuine errors */
2536 else if (error == SSL_ERROR_SSL)
2538 ERR_error_string(ERR_get_error(), ssl_errstring);
2539 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2540 ssl_xfer_error = TRUE;
2544 else if (error != SSL_ERROR_NONE)
2546 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2547 ssl_xfer_error = TRUE;
2551 #ifndef DISABLE_DKIM
2552 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2554 ssl_xfer_buffer_hwm = inbytes;
2555 ssl_xfer_buffer_lwm = 0;
2560 /*************************************************
2561 * TLS version of getc *
2562 *************************************************/
2564 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2565 it refills the buffer via the SSL reading function.
2567 Arguments: lim Maximum amount to read/buffer
2568 Returns: the next character or EOF
2570 Only used by the server-side TLS.
2574 tls_getc(unsigned lim)
2576 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2577 if (!tls_refill(lim))
2578 return ssl_xfer_error ? EOF : smtp_getc(lim);
2580 /* Something in the buffer; return next uschar */
2582 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2586 tls_getbuf(unsigned * len)
2591 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2592 if (!tls_refill(*len))
2594 if (!ssl_xfer_error) return smtp_getbuf(len);
2599 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
2601 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
2602 ssl_xfer_buffer_lwm += size;
2611 #ifndef DISABLE_DKIM
2612 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2614 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
2620 tls_could_read(void)
2622 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
2626 /*************************************************
2627 * Read bytes from TLS channel *
2628 *************************************************/
2635 Returns: the number of bytes read
2636 -1 after a failed read
2638 Only used by the client-side TLS.
2642 tls_read(BOOL is_server, uschar *buff, size_t len)
2644 SSL *ssl = is_server ? server_ssl : client_ssl;
2648 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2649 buff, (unsigned int)len);
2651 inbytes = SSL_read(ssl, CS buff, len);
2652 error = SSL_get_error(ssl, inbytes);
2654 if (error == SSL_ERROR_ZERO_RETURN)
2656 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2659 else if (error != SSL_ERROR_NONE)
2669 /*************************************************
2670 * Write bytes down TLS channel *
2671 *************************************************/
2675 is_server channel specifier
2678 more further data expected soon
2680 Returns: the number of bytes after a successful write,
2681 -1 after a failed write
2683 Used by both server-side and client-side TLS.
2687 tls_write(BOOL is_server, const uschar *buff, size_t len, BOOL more)
2689 int outbytes, error, left;
2690 SSL *ssl = is_server ? server_ssl : client_ssl;
2691 static gstring * corked = NULL;
2693 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
2694 buff, (unsigned long)len, more ? ", more" : "");
2696 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2697 "more" is notified. This hack is only ok if small amounts are involved AND only
2698 one stream does it, in one context (i.e. no store reset). Currently it is used
2699 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2701 if (is_server && (more || corked))
2703 corked = string_catn(corked, buff, len);
2706 buff = CUS corked->s;
2711 for (left = len; left > 0;)
2713 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2714 outbytes = SSL_write(ssl, CS buff, left);
2715 error = SSL_get_error(ssl, outbytes);
2716 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2720 ERR_error_string(ERR_get_error(), ssl_errstring);
2721 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2724 case SSL_ERROR_NONE:
2729 case SSL_ERROR_ZERO_RETURN:
2730 log_write(0, LOG_MAIN, "SSL channel closed on write");
2733 case SSL_ERROR_SYSCALL:
2734 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2735 sender_fullhost ? sender_fullhost : US"<unknown>",
2740 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2749 /*************************************************
2750 * Close down a TLS session *
2751 *************************************************/
2753 /* This is also called from within a delivery subprocess forked from the
2754 daemon, to shut down the TLS library, without actually doing a shutdown (which
2755 would tamper with the SSL session in the parent process).
2758 shutdown 1 if TLS close-alert is to be sent,
2759 2 if also response to be waited for
2763 Used by both server-side and client-side TLS.
2767 tls_close(BOOL is_server, int shutdown)
2769 SSL_CTX **ctxp = is_server ? &server_ctx : &client_ctx;
2770 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2771 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2773 if (*fdp < 0) return; /* TLS was not active */
2778 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2779 shutdown > 1 ? " (with response-wait)" : "");
2781 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
2785 rc = SSL_shutdown(*sslp); /* wait for response */
2789 if (rc < 0) DEBUG(D_tls)
2791 ERR_error_string(ERR_get_error(), ssl_errstring);
2792 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
2796 #ifndef DISABLE_OCSP
2799 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2800 server_static_cbinfo->verify_stack = NULL;
2804 SSL_CTX_free(*ctxp);
2814 /*************************************************
2815 * Let tls_require_ciphers be checked at startup *
2816 *************************************************/
2818 /* The tls_require_ciphers option, if set, must be something which the
2821 Returns: NULL on success, or error message
2825 tls_validate_require_cipher(void)
2828 uschar *s, *expciphers, *err;
2830 /* this duplicates from tls_init(), we need a better "init just global
2831 state, for no specific purpose" singleton function of our own */
2833 SSL_load_error_strings();
2834 OpenSSL_add_ssl_algorithms();
2835 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2836 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2837 list of available digests. */
2838 EVP_add_digest(EVP_sha256());
2841 if (!(tls_require_ciphers && *tls_require_ciphers))
2844 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
2846 return US"failed to expand tls_require_ciphers";
2848 if (!(expciphers && *expciphers))
2851 /* normalisation ripped from above */
2853 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2857 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
2858 if (!(ctx = SSL_CTX_new(TLS_server_method())))
2860 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
2863 ERR_error_string(ERR_get_error(), ssl_errstring);
2864 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2868 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2870 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2872 ERR_error_string(ERR_get_error(), ssl_errstring);
2873 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
2874 expciphers, ssl_errstring);
2885 /*************************************************
2886 * Report the library versions. *
2887 *************************************************/
2889 /* There have historically been some issues with binary compatibility in
2890 OpenSSL libraries; if Exim (like many other applications) is built against
2891 one version of OpenSSL but the run-time linker picks up another version,
2892 it can result in serious failures, including crashing with a SIGSEGV. So
2893 report the version found by the compiler and the run-time version.
2895 Note: some OS vendors backport security fixes without changing the version
2896 number/string, and the version date remains unchanged. The _build_ date
2897 will change, so we can more usefully assist with version diagnosis by also
2898 reporting the build date.
2900 Arguments: a FILE* to print the results to
2905 tls_version_report(FILE *f)
2907 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2910 OPENSSL_VERSION_TEXT,
2911 SSLeay_version(SSLEAY_VERSION),
2912 SSLeay_version(SSLEAY_BUILT_ON));
2913 /* third line is 38 characters for the %s and the line is 73 chars long;
2914 the OpenSSL output includes a "built on: " prefix already. */
2920 /*************************************************
2921 * Random number generation *
2922 *************************************************/
2924 /* Pseudo-random number generation. The result is not expected to be
2925 cryptographically strong but not so weak that someone will shoot themselves
2926 in the foot using it as a nonce in input in some email header scheme or
2927 whatever weirdness they'll twist this into. The result should handle fork()
2928 and avoid repeating sequences. OpenSSL handles that for us.
2932 Returns a random number in range [0, max-1]
2936 vaguely_random_number(int max)
2940 static pid_t pidlast = 0;
2943 uschar smallbuf[sizeof(r)];
2949 if (pidnow != pidlast)
2951 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2952 is unique for each thread", this doesn't apparently apply across processes,
2953 so our own warning from vaguely_random_number_fallback() applies here too.
2954 Fix per PostgreSQL. */
2960 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2964 gettimeofday(&r.tv, NULL);
2967 RAND_seed(US (&r), sizeof(r));
2969 /* We're after pseudo-random, not random; if we still don't have enough data
2970 in the internal PRNG then our options are limited. We could sleep and hope
2971 for entropy to come along (prayer technique) but if the system is so depleted
2972 in the first place then something is likely to just keep taking it. Instead,
2973 we'll just take whatever little bit of pseudo-random we can still manage to
2976 needed_len = sizeof(r);
2977 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2978 asked for a number less than 10. */
2979 for (r = max, i = 0; r; ++i)
2985 #ifdef EXIM_HAVE_RAND_PSEUDO
2986 /* We do not care if crypto-strong */
2987 i = RAND_pseudo_bytes(smallbuf, needed_len);
2989 i = RAND_bytes(smallbuf, needed_len);
2995 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2996 return vaguely_random_number_fallback(max);
3000 for (p = smallbuf; needed_len; --needed_len, ++p)
3006 /* We don't particularly care about weighted results; if someone wants
3007 smooth distribution and cares enough then they should submit a patch then. */
3014 /*************************************************
3015 * OpenSSL option parse *
3016 *************************************************/
3018 /* Parse one option for tls_openssl_options_parse below
3021 name one option name
3022 value place to store a value for it
3023 Returns success or failure in parsing
3026 struct exim_openssl_option {
3030 /* We could use a macro to expand, but we need the ifdef and not all the
3031 options document which version they were introduced in. Policylet: include
3032 all options unless explicitly for DTLS, let the administrator choose which
3035 This list is current as of:
3037 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
3039 static struct exim_openssl_option exim_openssl_options[] = {
3040 /* KEEP SORTED ALPHABETICALLY! */
3042 { US"all", SSL_OP_ALL },
3044 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
3045 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
3047 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
3048 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
3050 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
3051 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
3053 #ifdef SSL_OP_EPHEMERAL_RSA
3054 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
3056 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
3057 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
3059 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
3060 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
3062 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
3063 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
3065 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
3066 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
3068 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
3069 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
3071 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
3072 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
3074 #ifdef SSL_OP_NO_COMPRESSION
3075 { US"no_compression", SSL_OP_NO_COMPRESSION },
3077 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
3078 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
3080 #ifdef SSL_OP_NO_SSLv2
3081 { US"no_sslv2", SSL_OP_NO_SSLv2 },
3083 #ifdef SSL_OP_NO_SSLv3
3084 { US"no_sslv3", SSL_OP_NO_SSLv3 },
3086 #ifdef SSL_OP_NO_TICKET
3087 { US"no_ticket", SSL_OP_NO_TICKET },
3089 #ifdef SSL_OP_NO_TLSv1
3090 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
3092 #ifdef SSL_OP_NO_TLSv1_1
3093 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
3094 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
3095 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
3097 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
3100 #ifdef SSL_OP_NO_TLSv1_2
3101 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
3103 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
3104 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
3106 #ifdef SSL_OP_SINGLE_DH_USE
3107 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
3109 #ifdef SSL_OP_SINGLE_ECDH_USE
3110 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
3112 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
3113 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
3115 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
3116 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
3118 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
3119 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
3121 #ifdef SSL_OP_TLS_D5_BUG
3122 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
3124 #ifdef SSL_OP_TLS_ROLLBACK_BUG
3125 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
3128 static int exim_openssl_options_size =
3129 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
3133 tls_openssl_one_option_parse(uschar *name, long *value)
3136 int last = exim_openssl_options_size;
3137 while (last > first)
3139 int middle = (first + last)/2;
3140 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3143 *value = exim_openssl_options[middle].value;
3157 /*************************************************
3158 * OpenSSL option parsing logic *
3159 *************************************************/
3161 /* OpenSSL has a number of compatibility options which an administrator might
3162 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3163 we look like log_selector.
3166 option_spec the administrator-supplied string of options
3167 results ptr to long storage for the options bitmap
3168 Returns success or failure
3172 tls_openssl_options_parse(uschar *option_spec, long *results)
3177 BOOL adding, item_parsed;
3179 result = SSL_OP_NO_TICKET;
3180 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3181 * from default because it increases BEAST susceptibility. */
3182 #ifdef SSL_OP_NO_SSLv2
3183 result |= SSL_OP_NO_SSLv2;
3185 #ifdef SSL_OP_SINGLE_DH_USE
3186 result |= SSL_OP_SINGLE_DH_USE;
3195 for (s=option_spec; *s != '\0'; /**/)
3197 while (isspace(*s)) ++s;
3200 if (*s != '+' && *s != '-')
3202 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3203 "+ or - expected but found \"%s\"\n", s);
3206 adding = *s++ == '+';
3207 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3210 item_parsed = tls_openssl_one_option_parse(s, &item);
3214 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3217 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3218 adding ? "adding" : "removing", result, item, s);
3232 /* End of tls-openssl.c */