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
74 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
75 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
76 # define EXIM_HAVE_OPENSSL_CHECKHOST
80 #if !defined(LIBRESSL_VERSION_NUMBER) \
81 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
82 # if !defined(OPENSSL_NO_ECDH)
83 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
84 # define EXIM_HAVE_ECDH /*MMMM*/
86 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
87 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
92 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
93 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
97 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
98 # include <openssl/x509v3.h>
101 /* Structure for collecting random data for seeding. */
103 typedef struct randstuff {
108 /* Local static variables */
110 static BOOL client_verify_callback_called = FALSE;
111 static BOOL server_verify_callback_called = FALSE;
112 static const uschar *sid_ctx = US"exim";
114 /* We have three different contexts to care about.
116 Simple case: client, `client_ctx`
117 As a client, we can be doing a callout or cut-through delivery while receiving
118 a message. So we have a client context, which should have options initialised
119 from the SMTP Transport.
122 There are two cases: with and without ServerNameIndication from the client.
123 Given TLS SNI, we can be using different keys, certs and various other
124 configuration settings, because they're re-expanded with $tls_sni set. This
125 allows vhosting with TLS. This SNI is sent in the handshake.
126 A client might not send SNI, so we need a fallback, and an initial setup too.
127 So as a server, we start out using `server_ctx`.
128 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
129 `server_sni` from `server_ctx` and then initialise settings by re-expanding
133 static SSL_CTX *client_ctx = NULL;
134 static SSL_CTX *server_ctx = NULL;
135 static SSL *client_ssl = NULL;
136 static SSL *server_ssl = NULL;
138 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
139 static SSL_CTX *server_sni = NULL;
142 static char ssl_errstring[256];
144 static int ssl_session_timeout = 200;
145 static BOOL client_verify_optional = FALSE;
146 static BOOL server_verify_optional = FALSE;
148 static BOOL reexpand_tls_files_for_sni = FALSE;
151 typedef struct tls_ext_ctx_cb {
155 STACK_OF(X509_NAME) * acceptable_certnames;
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), 0);
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 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1222 ERR_error_string(ERR_get_error(), ssl_errstring);
1223 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1224 return SSL_TLSEXT_ERR_NOACK;
1227 /* Not sure how many of these are actually needed, since SSL object
1228 already exists. Might even need this selfsame callback, for reneg? */
1230 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1231 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1232 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1233 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1234 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1235 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1237 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1238 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1240 return SSL_TLSEXT_ERR_NOACK;
1242 if (cbinfo->server_cipher_list)
1243 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
1244 #ifndef DISABLE_OCSP
1245 if (cbinfo->u_ocsp.server.file)
1247 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1248 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1252 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1253 verify_callback_server, &dummy_errstr)) != OK)
1254 return SSL_TLSEXT_ERR_NOACK;
1256 /* do this after setup_certs, because this can require the certs for verifying
1257 OCSP information. */
1258 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1259 return SSL_TLSEXT_ERR_NOACK;
1261 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1262 SSL_set_SSL_CTX(s, server_sni);
1264 return SSL_TLSEXT_ERR_OK;
1266 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1271 #ifndef DISABLE_OCSP
1273 /*************************************************
1274 * Callback to handle OCSP Stapling *
1275 *************************************************/
1277 /* Called when acting as server during the TLS session setup if the client
1278 requests OCSP information with a Certificate Status Request.
1280 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1286 tls_server_stapling_cb(SSL *s, void *arg)
1288 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1289 uschar *response_der; /*XXX blob */
1290 int response_der_len;
1292 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1293 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1294 buggy in current OpenSSL; it returns the last cert loaded always rather than
1295 the one actually presented. So we can't support a stack of OCSP proofs at
1299 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1300 cbinfo->u_ocsp.server.response ? "have" : "lack");
1302 tls_in.ocsp = OCSP_NOT_RESP;
1303 if (!cbinfo->u_ocsp.server.response)
1304 return SSL_TLSEXT_ERR_NOACK;
1306 response_der = NULL;
1307 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1309 if (response_der_len <= 0)
1310 return SSL_TLSEXT_ERR_NOACK;
1312 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1313 tls_in.ocsp = OCSP_VFIED;
1314 return SSL_TLSEXT_ERR_OK;
1319 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1321 BIO_printf(bp, "\t%s: ", str);
1322 ASN1_GENERALIZEDTIME_print(bp, time);
1327 tls_client_stapling_cb(SSL *s, void *arg)
1329 tls_ext_ctx_cb * cbinfo = arg;
1330 const unsigned char * p;
1332 OCSP_RESPONSE * rsp;
1333 OCSP_BASICRESP * bs;
1336 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1337 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1340 /* Expect this when we requested ocsp but got none */
1341 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1342 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1344 DEBUG(D_tls) debug_printf(" null\n");
1345 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1348 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1350 tls_out.ocsp = OCSP_FAILED;
1351 if (LOGGING(tls_cipher))
1352 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1354 DEBUG(D_tls) debug_printf(" parse error\n");
1358 if(!(bs = OCSP_response_get1_basic(rsp)))
1360 tls_out.ocsp = OCSP_FAILED;
1361 if (LOGGING(tls_cipher))
1362 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1364 DEBUG(D_tls) debug_printf(" error parsing response\n");
1365 OCSP_RESPONSE_free(rsp);
1369 /* We'd check the nonce here if we'd put one in the request. */
1370 /* However that would defeat cacheability on the server so we don't. */
1372 /* This section of code reworked from OpenSSL apps source;
1373 The OpenSSL Project retains copyright:
1374 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1379 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1381 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1383 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1385 /* Use the chain that verified the server cert to verify the stapled info */
1386 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1388 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1389 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1391 tls_out.ocsp = OCSP_FAILED;
1392 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1393 "Received TLS cert status response, itself unverifiable: %s",
1394 ERR_reason_error_string(ERR_peek_error()));
1395 BIO_printf(bp, "OCSP response verify failure\n");
1396 ERR_print_errors(bp);
1397 OCSP_RESPONSE_print(bp, rsp, 0);
1401 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1403 /*XXX So we have a good stapled OCSP status. How do we know
1404 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1405 OCSP_resp_find_status() which matches on a cert id, which presumably
1406 we should use. Making an id needs OCSP_cert_id_new(), which takes
1407 issuerName, issuerKey, serialNumber. Are they all in the cert?
1409 For now, carry on blindly accepting the resp. */
1412 OCSP_SINGLERESP * single;
1414 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1415 if (OCSP_resp_count(bs) != 1)
1417 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1418 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1421 tls_out.ocsp = OCSP_FAILED;
1422 log_write(0, LOG_MAIN, "OCSP stapling "
1423 "with multiple responses not handled");
1426 single = OCSP_resp_get0(bs, 0);
1427 status = OCSP_single_get0_status(single, &reason, &rev,
1428 &thisupd, &nextupd);
1431 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1432 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1433 if (!OCSP_check_validity(thisupd, nextupd,
1434 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1436 tls_out.ocsp = OCSP_FAILED;
1437 DEBUG(D_tls) ERR_print_errors(bp);
1438 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1442 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1443 OCSP_cert_status_str(status));
1446 case V_OCSP_CERTSTATUS_GOOD:
1447 tls_out.ocsp = OCSP_VFIED;
1450 case V_OCSP_CERTSTATUS_REVOKED:
1451 tls_out.ocsp = OCSP_FAILED;
1452 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1453 reason != -1 ? "; reason: " : "",
1454 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1455 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1458 tls_out.ocsp = OCSP_FAILED;
1459 log_write(0, LOG_MAIN,
1460 "Server certificate status unknown, in OCSP stapling");
1465 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1470 OCSP_RESPONSE_free(rsp);
1473 #endif /*!DISABLE_OCSP*/
1476 /*************************************************
1477 * Initialize for TLS *
1478 *************************************************/
1480 /* Called from both server and client code, to do preliminary initialization
1481 of the library. We allocate and return a context structure.
1484 ctxp returned SSL context
1485 host connected host, if client; NULL if server
1486 dhparam DH parameter file
1487 certificate certificate file
1488 privatekey private key
1489 ocsp_file file of stapling info (server); flag for require ocsp (client)
1490 addr address if client; NULL if server (for some randomness)
1491 cbp place to put allocated callback context
1492 errstr error string pointer
1494 Returns: OK/DEFER/FAIL
1498 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1500 #ifndef DISABLE_OCSP
1501 uschar *ocsp_file, /*XXX stack, in server*/
1503 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
1508 tls_ext_ctx_cb * cbinfo;
1510 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1511 cbinfo->certificate = certificate;
1512 cbinfo->privatekey = privatekey;
1513 cbinfo->is_server = host==NULL;
1514 cbinfo->acceptable_certnames = NULL;
1515 #ifndef DISABLE_OCSP
1516 cbinfo->verify_stack = NULL;
1519 cbinfo->u_ocsp.server.file = ocsp_file;
1520 cbinfo->u_ocsp.server.file_expanded = NULL;
1521 cbinfo->u_ocsp.server.response = NULL;
1524 cbinfo->u_ocsp.client.verify_store = NULL;
1526 cbinfo->dhparam = dhparam;
1527 cbinfo->server_cipher_list = NULL;
1528 cbinfo->host = host;
1529 #ifndef DISABLE_EVENT
1530 cbinfo->event_action = NULL;
1533 SSL_load_error_strings(); /* basic set up */
1534 OpenSSL_add_ssl_algorithms();
1536 #ifdef EXIM_HAVE_SHA256
1537 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1538 list of available digests. */
1539 EVP_add_digest(EVP_sha256());
1542 /* Create a context.
1543 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1544 negotiation in the different methods; as far as I can tell, the only
1545 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1546 when OpenSSL is built without SSLv2 support.
1547 By disabling with openssl_options, we can let admins re-enable with the
1550 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1551 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1553 /* It turns out that we need to seed the random number generator this early in
1554 order to get the full complement of ciphers to work. It took me roughly a day
1555 of work to discover this by experiment.
1557 On systems that have /dev/urandom, SSL may automatically seed itself from
1558 there. Otherwise, we have to make something up as best we can. Double check
1564 gettimeofday(&r.tv, NULL);
1567 RAND_seed(US (&r), sizeof(r));
1568 RAND_seed(US big_buffer, big_buffer_size);
1569 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1572 return tls_error(US"RAND_status", host,
1573 US"unable to seed random number generator", errstr);
1576 /* Set up the information callback, which outputs if debugging is at a suitable
1579 DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1581 /* Automatically re-try reads/writes after renegotiation. */
1582 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1584 /* Apply administrator-supplied work-arounds.
1585 Historically we applied just one requested option,
1586 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1587 moved to an administrator-controlled list of options to specify and
1588 grandfathered in the first one as the default value for "openssl_options".
1590 No OpenSSL version number checks: the options we accept depend upon the
1591 availability of the option value macros from OpenSSL. */
1593 if (!tls_openssl_options_parse(openssl_options, &init_options))
1594 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1598 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1599 if (!(SSL_CTX_set_options(ctx, init_options)))
1600 return tls_error(string_sprintf(
1601 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
1604 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1606 /* Disable session cache unconditionally */
1608 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
1610 /* Initialize with DH parameters if supplied */
1611 /* Initialize ECDH temp key parameter selection */
1613 if ( !init_dh(ctx, dhparam, host, errstr)
1614 || !init_ecdh(ctx, host, errstr)
1618 /* Set up certificate and key (and perhaps OCSP info) */
1620 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
1623 /* If we need to handle SNI or OCSP, do so */
1625 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1626 # ifndef DISABLE_OCSP
1627 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1629 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1634 if (host == NULL) /* server */
1636 # ifndef DISABLE_OCSP
1637 /* We check u_ocsp.server.file, not server.response, because we care about if
1638 the option exists, not what the current expansion might be, as SNI might
1639 change the certificate and OCSP file in use between now and the time the
1640 callback is invoked. */
1641 if (cbinfo->u_ocsp.server.file)
1643 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
1644 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1647 /* We always do this, so that $tls_sni is available even if not used in
1649 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
1650 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
1652 # ifndef DISABLE_OCSP
1654 if(ocsp_file) /* wanting stapling */
1656 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1658 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1661 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
1662 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1667 cbinfo->verify_cert_hostnames = NULL;
1669 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1670 /* Set up the RSA callback */
1671 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
1674 /* Finally, set the timeout, and we are done */
1676 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
1677 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1688 /*************************************************
1689 * Get name of cipher in use *
1690 *************************************************/
1693 Argument: pointer to an SSL structure for the connection
1694 buffer to use for answer
1696 pointer to number of bits for cipher
1701 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1703 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1704 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1705 the accessor functions use const in the prototype. */
1706 const SSL_CIPHER *c;
1709 ver = (const uschar *)SSL_get_version(ssl);
1711 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1712 SSL_CIPHER_get_bits(c, bits);
1714 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1715 SSL_CIPHER_get_name(c), *bits);
1717 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1722 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1724 /*XXX we might consider a list-of-certs variable for the cert chain.
1725 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1726 in list-handling functions, also consider the difference between the entire
1727 chain and the elements sent by the peer. */
1729 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1730 if (!tlsp->peercert)
1731 tlsp->peercert = SSL_get_peer_certificate(ssl);
1732 /* Beware anonymous ciphers which lead to server_cert being NULL */
1735 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1736 peerdn[bsize-1] = '\0';
1737 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1740 tlsp->peerdn = NULL;
1747 /*************************************************
1748 * Set up for verifying certificates *
1749 *************************************************/
1751 /* Load certs from file, return TRUE on success */
1754 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1759 while (sk_X509_num(verify_stack) > 0)
1760 X509_free(sk_X509_pop(verify_stack));
1762 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1763 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1764 sk_X509_push(verify_stack, x);
1771 /* Called by both client and server startup; on the server possibly
1772 repeated after a Server Name Indication.
1775 sctx SSL_CTX* to initialise
1776 certs certs file or NULL
1777 crl CRL file or NULL
1778 host NULL in a server; the remote host in a client
1779 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1780 otherwise passed as FALSE
1781 cert_vfy_cb Callback function for certificate verification
1782 errstr error string pointer
1784 Returns: OK/DEFER/FAIL
1788 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1789 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
1791 uschar *expcerts, *expcrl;
1793 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
1795 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
1797 if (expcerts && *expcerts)
1799 /* Tell the library to use its compiled-in location for the system default
1800 CA bundle. Then add the ones specified in the config, if any. */
1802 if (!SSL_CTX_set_default_verify_paths(sctx))
1803 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
1805 if (Ustrcmp(expcerts, "system") != 0)
1807 struct stat statbuf;
1809 if (Ustat(expcerts, &statbuf) < 0)
1811 log_write(0, LOG_MAIN|LOG_PANIC,
1812 "failed to stat %s for certificates", expcerts);
1818 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1819 { file = NULL; dir = expcerts; }
1822 /*XXX somewhere down here we leak memory per-STARTTLS, on a multi-message conn, server-side */
1823 file = expcerts; dir = NULL;
1824 #ifndef DISABLE_OCSP
1825 /* In the server if we will be offering an OCSP proof, load chain from
1826 file for verifying the OCSP proof at load time. */
1829 && statbuf.st_size > 0
1830 && server_static_cbinfo->u_ocsp.server.file
1831 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
1834 log_write(0, LOG_MAIN|LOG_PANIC,
1835 "failed to load cert chain from %s", file);
1841 /* If a certificate file is empty, the next function fails with an
1842 unhelpful error message. If we skip it, we get the correct behaviour (no
1843 certificates are recognized, but the error message is still misleading (it
1844 says no certificate was supplied). But this is better. */
1846 if ( (!file || statbuf.st_size > 0)
1847 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1848 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
1850 /* Load the list of CAs for which we will accept certs, for sending
1851 to the client. This is only for the one-file tls_verify_certificates
1853 If a list isn't loaded into the server, but
1854 some verify locations are set, the server end appears to make
1855 a wildcard request for client certs.
1856 Meanwhile, the client library as default behaviour *ignores* the list
1857 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1858 Because of this, and that the dir variant is likely only used for
1859 the public-CA bundle (not for a private CA), not worth fixing.
1863 tls_ext_ctx_cb * cbinfo = host
1864 ? client_static_cbinfo : server_static_cbinfo;
1865 STACK_OF(X509_NAME) * names;
1867 if ((names = cbinfo->acceptable_certnames))
1869 sk_X509_NAME_pop_free(names, X509_NAME_free);
1870 cbinfo->acceptable_certnames = NULL;
1872 names = SSL_load_client_CA_file(CS file);
1874 SSL_CTX_set_client_CA_list(sctx, names);
1875 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1876 sk_X509_NAME_num(names));
1877 cbinfo->acceptable_certnames = names;
1882 /* Handle a certificate revocation list. */
1884 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1886 /* This bit of code is now the version supplied by Lars Mainka. (I have
1887 merely reformatted it into the Exim code style.)
1889 "From here I changed the code to add support for multiple crl's
1890 in pem format in one file or to support hashed directory entries in
1891 pem format instead of a file. This method now uses the library function
1892 X509_STORE_load_locations to add the CRL location to the SSL context.
1893 OpenSSL will then handle the verify against CA certs and CRLs by
1894 itself in the verify callback." */
1896 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
1897 if (expcrl && *expcrl)
1899 struct stat statbufcrl;
1900 if (Ustat(expcrl, &statbufcrl) < 0)
1902 log_write(0, LOG_MAIN|LOG_PANIC,
1903 "failed to stat %s for certificates revocation lists", expcrl);
1908 /* is it a file or directory? */
1910 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1911 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1915 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1921 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1923 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1924 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
1926 /* setting the flags to check against the complete crl chain */
1928 X509_STORE_set_flags(cvstore,
1929 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1933 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1935 /* If verification is optional, don't fail if no certificate */
1937 SSL_CTX_set_verify(sctx,
1938 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1947 /*************************************************
1948 * Start a TLS session in a server *
1949 *************************************************/
1951 /* This is called when Exim is running as a server, after having received
1952 the STARTTLS command. It must respond to that command, and then negotiate
1956 require_ciphers allowed ciphers
1957 errstr pointer to error message
1959 Returns: OK on success
1960 DEFER for errors before the start of the negotiation
1961 FAIL for errors during the negotiation; the server can't
1966 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
1969 uschar * expciphers;
1970 tls_ext_ctx_cb * cbinfo;
1971 static uschar peerdn[256];
1972 static uschar cipherbuf[256];
1974 /* Check for previous activation */
1976 if (tls_in.active >= 0)
1978 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
1979 smtp_printf("554 Already in TLS\r\n", FALSE);
1983 /* Initialize the SSL library. If it fails, it will already have logged
1986 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1987 #ifndef DISABLE_OCSP
1988 tls_ocsp_file, /*XXX stack*/
1990 NULL, &server_static_cbinfo, errstr);
1991 if (rc != OK) return rc;
1992 cbinfo = server_static_cbinfo;
1994 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
1997 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1998 were historically separated by underscores. So that I can use either form in my
1999 tests, and also for general convenience, we turn underscores into hyphens here.
2004 uschar * s = expciphers;
2005 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2006 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2007 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2008 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2009 cbinfo->server_cipher_list = expciphers;
2012 /* If this is a host for which certificate verification is mandatory or
2013 optional, set up appropriately. */
2015 tls_in.certificate_verified = FALSE;
2017 tls_in.dane_verified = FALSE;
2019 server_verify_callback_called = FALSE;
2021 if (verify_check_host(&tls_verify_hosts) == OK)
2023 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2024 FALSE, verify_callback_server, errstr);
2025 if (rc != OK) return rc;
2026 server_verify_optional = FALSE;
2028 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2030 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2031 TRUE, verify_callback_server, errstr);
2032 if (rc != OK) return rc;
2033 server_verify_optional = TRUE;
2036 /* Prepare for new connection */
2038 if (!(server_ssl = SSL_new(server_ctx)))
2039 return tls_error(US"SSL_new", NULL, NULL, errstr);
2041 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2043 * With the SSL_clear(), we get strange interoperability bugs with
2044 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2045 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2047 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2048 * session shutdown. In this case, we have a brand new object and there's no
2049 * obvious reason to immediately clear it. I'm guessing that this was
2050 * originally added because of incomplete initialisation which the clear fixed,
2051 * in some historic release.
2054 /* Set context and tell client to go ahead, except in the case of TLS startup
2055 on connection, where outputting anything now upsets the clients and tends to
2056 make them disconnect. We need to have an explicit fflush() here, to force out
2057 the response. Other smtp_printf() calls do not need it, because in non-TLS
2058 mode, the fflush() happens when smtp_getc() is called. */
2060 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2061 if (!tls_in.on_connect)
2063 smtp_printf("220 TLS go ahead\r\n", FALSE);
2067 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2068 that the OpenSSL library doesn't. */
2070 SSL_set_wfd(server_ssl, fileno(smtp_out));
2071 SSL_set_rfd(server_ssl, fileno(smtp_in));
2072 SSL_set_accept_state(server_ssl);
2074 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2076 sigalrm_seen = FALSE;
2077 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2078 rc = SSL_accept(server_ssl);
2083 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2087 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2089 /* TLS has been set up. Adjust the input functions to read via TLS,
2090 and initialize things. */
2092 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2094 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
2095 tls_in.cipher = cipherbuf;
2100 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
2101 debug_printf("Shared ciphers: %s\n", buf);
2104 /* Record the certificate we presented */
2106 X509 * crt = SSL_get_certificate(server_ssl);
2107 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2110 /* Only used by the server-side tls (tls_in), including tls_getc.
2111 Client-side (tls_out) reads (seem to?) go via
2112 smtp_read_response()/ip_recv().
2113 Hence no need to duplicate for _in and _out.
2115 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2116 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2117 ssl_xfer_eof = ssl_xfer_error = 0;
2119 receive_getc = tls_getc;
2120 receive_getbuf = tls_getbuf;
2121 receive_get_cache = tls_get_cache;
2122 receive_ungetc = tls_ungetc;
2123 receive_feof = tls_feof;
2124 receive_ferror = tls_ferror;
2125 receive_smtp_buffered = tls_smtp_buffered;
2127 tls_in.active = fileno(smtp_out);
2135 tls_client_basic_ctx_init(SSL_CTX * ctx,
2136 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2140 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2141 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2142 the specified host patterns if one of them is defined */
2144 if ( ( !ob->tls_verify_hosts
2145 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2147 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
2149 client_verify_optional = FALSE;
2150 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
2151 client_verify_optional = TRUE;
2155 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2156 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2160 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
2162 cbinfo->verify_cert_hostnames =
2164 string_domain_utf8_to_alabel(host->name, NULL);
2168 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2169 cbinfo->verify_cert_hostnames);
2177 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2181 const char * hostnames[2] = { CS host->name, NULL };
2184 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2185 return tls_error(US"hostnames load", host, NULL, errstr);
2187 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2189 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2190 ) if (rr->type == T_TLSA)
2192 const uschar * p = rr->data;
2193 uint8_t usage, selector, mtype;
2194 const char * mdname;
2198 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2199 if (usage != 2 && usage != 3) continue;
2206 default: continue; /* Only match-types 0, 1, 2 are supported */
2207 case 0: mdname = NULL; break;
2208 case 1: mdname = "sha256"; break;
2209 case 2: mdname = "sha512"; break;
2213 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2216 return tls_error(US"tlsa load", host, NULL, errstr);
2217 case 0: /* action not taken */
2221 tls_out.tlsa_usage |= 1<<usage;
2227 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2230 #endif /*SUPPORT_DANE*/
2234 /*************************************************
2235 * Start a TLS session in a client *
2236 *************************************************/
2238 /* Called from the smtp transport after STARTTLS has been accepted.
2241 fd the fd of the connection
2242 host connected host (for messages)
2243 addr the first address
2244 tb transport (always smtp)
2245 tlsa_dnsa tlsa lookup, if DANE, else null
2246 errstr error string pointer
2248 Returns: OK on success
2249 FAIL otherwise - note that tls_error() will not give DEFER
2250 because this is not a server
2254 tls_client_start(int fd, host_item *host, address_item *addr,
2255 transport_instance * tb,
2257 dns_answer * tlsa_dnsa,
2261 smtp_transport_options_block * ob =
2262 (smtp_transport_options_block *)tb->options_block;
2263 static uschar peerdn[256];
2264 uschar * expciphers;
2266 static uschar cipherbuf[256];
2268 #ifndef DISABLE_OCSP
2269 BOOL request_ocsp = FALSE;
2270 BOOL require_ocsp = FALSE;
2274 tls_out.tlsa_usage = 0;
2277 #ifndef DISABLE_OCSP
2279 # ifdef SUPPORT_DANE
2281 && ob->hosts_request_ocsp[0] == '*'
2282 && ob->hosts_request_ocsp[1] == '\0'
2285 /* Unchanged from default. Use a safer one under DANE */
2286 request_ocsp = TRUE;
2287 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2288 " {= {4}{$tls_out_tlsa_usage}} } "
2294 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
2295 request_ocsp = TRUE;
2297 # ifdef SUPPORT_DANE
2301 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2305 rc = tls_init(&client_ctx, host, NULL,
2306 ob->tls_certificate, ob->tls_privatekey,
2307 #ifndef DISABLE_OCSP
2308 (void *)(long)request_ocsp,
2310 addr, &client_static_cbinfo, errstr);
2311 if (rc != OK) return rc;
2313 tls_out.certificate_verified = FALSE;
2314 client_verify_callback_called = FALSE;
2316 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2317 &expciphers, errstr))
2320 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2321 are separated by underscores. So that I can use either form in my tests, and
2322 also for general convenience, we turn underscores into hyphens here. */
2326 uschar *s = expciphers;
2327 while (*s) { if (*s == '_') *s = '-'; s++; }
2328 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2329 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
2330 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2336 SSL_CTX_set_verify(client_ctx,
2337 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2338 verify_callback_client_dane);
2340 if (!DANESSL_library_init())
2341 return tls_error(US"library init", host, NULL, errstr);
2342 if (DANESSL_CTX_init(client_ctx) <= 0)
2343 return tls_error(US"context init", host, NULL, errstr);
2349 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob,
2350 client_static_cbinfo, errstr)) != OK)
2353 if ((client_ssl = SSL_new(client_ctx)) == NULL)
2354 return tls_error(US"SSL_new", host, NULL, errstr);
2355 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
2356 SSL_set_fd(client_ssl, fd);
2357 SSL_set_connect_state(client_ssl);
2361 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni, errstr))
2365 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2367 else if (!Ustrlen(tls_out.sni))
2371 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2372 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
2373 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
2375 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2383 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa, errstr)) != OK)
2387 #ifndef DISABLE_OCSP
2388 /* Request certificate status at connection-time. If the server
2389 does OCSP stapling we will get the callback (set in tls_init()) */
2390 # ifdef SUPPORT_DANE
2394 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2395 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2397 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2398 this means we avoid the OCSP request, we wasted the setup
2399 cost in tls_init(). */
2400 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2401 request_ocsp = require_ocsp
2402 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2409 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
2410 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2411 tls_out.ocsp = OCSP_NOT_RESP;
2415 #ifndef DISABLE_EVENT
2416 client_static_cbinfo->event_action = tb->event_action;
2419 /* There doesn't seem to be a built-in timeout on connection. */
2421 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2422 sigalrm_seen = FALSE;
2423 alarm(ob->command_timeout);
2424 rc = SSL_connect(client_ssl);
2429 DANESSL_cleanup(client_ssl);
2433 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL,
2436 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2438 peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
2440 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2441 tls_out.cipher = cipherbuf;
2443 /* Record the certificate we presented */
2445 X509 * crt = SSL_get_certificate(client_ssl);
2446 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2449 tls_out.active = fd;
2458 tls_refill(unsigned lim)
2463 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2464 ssl_xfer_buffer, ssl_xfer_buffer_size);
2466 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2467 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2468 MIN(ssl_xfer_buffer_size, lim));
2469 error = SSL_get_error(server_ssl, inbytes);
2472 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2473 closed down, not that the socket itself has been closed down. Revert to
2474 non-SSL handling. */
2476 if (error == SSL_ERROR_ZERO_RETURN)
2478 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2480 receive_getc = smtp_getc;
2481 receive_getbuf = smtp_getbuf;
2482 receive_get_cache = smtp_get_cache;
2483 receive_ungetc = smtp_ungetc;
2484 receive_feof = smtp_feof;
2485 receive_ferror = smtp_ferror;
2486 receive_smtp_buffered = smtp_buffered;
2488 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2489 SSL_shutdown(server_ssl);
2491 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2492 sk_X509_NAME_pop_free(server_static_cbinfo->acceptable_certnames, X509_NAME_free);
2493 SSL_free(server_ssl);
2494 SSL_CTX_free(server_ctx);
2495 server_static_cbinfo->verify_stack = NULL;
2496 server_static_cbinfo->acceptable_certnames = NULL;
2501 tls_in.cipher = NULL;
2502 tls_in.peerdn = NULL;
2508 /* Handle genuine errors */
2510 else if (error == SSL_ERROR_SSL)
2512 ERR_error_string(ERR_get_error(), ssl_errstring);
2513 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2518 else if (error != SSL_ERROR_NONE)
2520 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2525 #ifndef DISABLE_DKIM
2526 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2528 ssl_xfer_buffer_hwm = inbytes;
2529 ssl_xfer_buffer_lwm = 0;
2534 /*************************************************
2535 * TLS version of getc *
2536 *************************************************/
2538 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2539 it refills the buffer via the SSL reading function.
2541 Arguments: lim Maximum amount to read/buffer
2542 Returns: the next character or EOF
2544 Only used by the server-side TLS.
2548 tls_getc(unsigned lim)
2550 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2551 if (!tls_refill(lim))
2552 return ssl_xfer_error ? EOF : smtp_getc(lim);
2554 /* Something in the buffer; return next uschar */
2556 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2560 tls_getbuf(unsigned * len)
2565 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2566 if (!tls_refill(*len))
2568 if (!ssl_xfer_error) return smtp_getbuf(len);
2573 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
2575 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
2576 ssl_xfer_buffer_lwm += size;
2585 #ifndef DISABLE_DKIM
2586 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2588 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
2594 tls_could_read(void)
2596 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
2600 /*************************************************
2601 * Read bytes from TLS channel *
2602 *************************************************/
2609 Returns: the number of bytes read
2610 -1 after a failed read
2612 Only used by the client-side TLS.
2616 tls_read(BOOL is_server, uschar *buff, size_t len)
2618 SSL *ssl = is_server ? server_ssl : client_ssl;
2622 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2623 buff, (unsigned int)len);
2625 inbytes = SSL_read(ssl, CS buff, len);
2626 error = SSL_get_error(ssl, inbytes);
2628 if (error == SSL_ERROR_ZERO_RETURN)
2630 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2633 else if (error != SSL_ERROR_NONE)
2643 /*************************************************
2644 * Write bytes down TLS channel *
2645 *************************************************/
2649 is_server channel specifier
2652 more further data expected soon
2654 Returns: the number of bytes after a successful write,
2655 -1 after a failed write
2657 Used by both server-side and client-side TLS.
2661 tls_write(BOOL is_server, const uschar *buff, size_t len, BOOL more)
2663 int outbytes, error, left;
2664 SSL *ssl = is_server ? server_ssl : client_ssl;
2665 static gstring * corked = NULL;
2667 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
2668 buff, (unsigned long)len, more ? ", more" : "");
2670 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2671 "more" is notified. This hack is only ok if small amounts are involved AND only
2672 one stream does it, in one context (i.e. no store reset). Currently it is used
2673 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2675 if (is_server && (more || corked))
2677 corked = string_catn(corked, buff, len);
2680 buff = CUS corked->s;
2685 for (left = len; left > 0;)
2687 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2688 outbytes = SSL_write(ssl, CS buff, left);
2689 error = SSL_get_error(ssl, outbytes);
2690 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2694 ERR_error_string(ERR_get_error(), ssl_errstring);
2695 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2698 case SSL_ERROR_NONE:
2703 case SSL_ERROR_ZERO_RETURN:
2704 log_write(0, LOG_MAIN, "SSL channel closed on write");
2707 case SSL_ERROR_SYSCALL:
2708 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2709 sender_fullhost ? sender_fullhost : US"<unknown>",
2714 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2723 /*************************************************
2724 * Close down a TLS session *
2725 *************************************************/
2727 /* This is also called from within a delivery subprocess forked from the
2728 daemon, to shut down the TLS library, without actually doing a shutdown (which
2729 would tamper with the SSL session in the parent process).
2732 shutdown 1 if TLS close-alert is to be sent,
2733 2 if also response to be waited for
2737 Used by both server-side and client-side TLS.
2741 tls_close(BOOL is_server, int shutdown)
2743 SSL_CTX **ctxp = is_server ? &server_ctx : &client_ctx;
2744 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2745 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2747 if (*fdp < 0) return; /* TLS was not active */
2752 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2753 shutdown > 1 ? " (with response-wait)" : "");
2755 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
2759 rc = SSL_shutdown(*sslp); /* wait for response */
2763 if (rc < 0) DEBUG(D_tls)
2765 ERR_error_string(ERR_get_error(), ssl_errstring);
2766 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
2772 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2773 sk_X509_NAME_pop_free(server_static_cbinfo->acceptable_certnames,
2775 server_static_cbinfo->verify_stack = NULL;
2776 server_static_cbinfo->acceptable_certnames = NULL;
2779 SSL_CTX_free(*ctxp);
2789 /*************************************************
2790 * Let tls_require_ciphers be checked at startup *
2791 *************************************************/
2793 /* The tls_require_ciphers option, if set, must be something which the
2796 Returns: NULL on success, or error message
2800 tls_validate_require_cipher(void)
2803 uschar *s, *expciphers, *err;
2805 /* this duplicates from tls_init(), we need a better "init just global
2806 state, for no specific purpose" singleton function of our own */
2808 SSL_load_error_strings();
2809 OpenSSL_add_ssl_algorithms();
2810 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2811 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2812 list of available digests. */
2813 EVP_add_digest(EVP_sha256());
2816 if (!(tls_require_ciphers && *tls_require_ciphers))
2819 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
2821 return US"failed to expand tls_require_ciphers";
2823 if (!(expciphers && *expciphers))
2826 /* normalisation ripped from above */
2828 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2832 ctx = SSL_CTX_new(SSLv23_server_method());
2835 ERR_error_string(ERR_get_error(), ssl_errstring);
2836 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2840 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2842 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2844 ERR_error_string(ERR_get_error(), ssl_errstring);
2845 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
2846 expciphers, ssl_errstring);
2857 /*************************************************
2858 * Report the library versions. *
2859 *************************************************/
2861 /* There have historically been some issues with binary compatibility in
2862 OpenSSL libraries; if Exim (like many other applications) is built against
2863 one version of OpenSSL but the run-time linker picks up another version,
2864 it can result in serious failures, including crashing with a SIGSEGV. So
2865 report the version found by the compiler and the run-time version.
2867 Note: some OS vendors backport security fixes without changing the version
2868 number/string, and the version date remains unchanged. The _build_ date
2869 will change, so we can more usefully assist with version diagnosis by also
2870 reporting the build date.
2872 Arguments: a FILE* to print the results to
2877 tls_version_report(FILE *f)
2879 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2882 OPENSSL_VERSION_TEXT,
2883 SSLeay_version(SSLEAY_VERSION),
2884 SSLeay_version(SSLEAY_BUILT_ON));
2885 /* third line is 38 characters for the %s and the line is 73 chars long;
2886 the OpenSSL output includes a "built on: " prefix already. */
2892 /*************************************************
2893 * Random number generation *
2894 *************************************************/
2896 /* Pseudo-random number generation. The result is not expected to be
2897 cryptographically strong but not so weak that someone will shoot themselves
2898 in the foot using it as a nonce in input in some email header scheme or
2899 whatever weirdness they'll twist this into. The result should handle fork()
2900 and avoid repeating sequences. OpenSSL handles that for us.
2904 Returns a random number in range [0, max-1]
2908 vaguely_random_number(int max)
2912 static pid_t pidlast = 0;
2915 uschar smallbuf[sizeof(r)];
2921 if (pidnow != pidlast)
2923 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2924 is unique for each thread", this doesn't apparently apply across processes,
2925 so our own warning from vaguely_random_number_fallback() applies here too.
2926 Fix per PostgreSQL. */
2932 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2936 gettimeofday(&r.tv, NULL);
2939 RAND_seed(US (&r), sizeof(r));
2941 /* We're after pseudo-random, not random; if we still don't have enough data
2942 in the internal PRNG then our options are limited. We could sleep and hope
2943 for entropy to come along (prayer technique) but if the system is so depleted
2944 in the first place then something is likely to just keep taking it. Instead,
2945 we'll just take whatever little bit of pseudo-random we can still manage to
2948 needed_len = sizeof(r);
2949 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2950 asked for a number less than 10. */
2951 for (r = max, i = 0; r; ++i)
2957 #ifdef EXIM_HAVE_RAND_PSEUDO
2958 /* We do not care if crypto-strong */
2959 i = RAND_pseudo_bytes(smallbuf, needed_len);
2961 i = RAND_bytes(smallbuf, needed_len);
2967 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2968 return vaguely_random_number_fallback(max);
2972 for (p = smallbuf; needed_len; --needed_len, ++p)
2978 /* We don't particularly care about weighted results; if someone wants
2979 smooth distribution and cares enough then they should submit a patch then. */
2986 /*************************************************
2987 * OpenSSL option parse *
2988 *************************************************/
2990 /* Parse one option for tls_openssl_options_parse below
2993 name one option name
2994 value place to store a value for it
2995 Returns success or failure in parsing
2998 struct exim_openssl_option {
3002 /* We could use a macro to expand, but we need the ifdef and not all the
3003 options document which version they were introduced in. Policylet: include
3004 all options unless explicitly for DTLS, let the administrator choose which
3007 This list is current as of:
3009 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
3011 static struct exim_openssl_option exim_openssl_options[] = {
3012 /* KEEP SORTED ALPHABETICALLY! */
3014 { US"all", SSL_OP_ALL },
3016 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
3017 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
3019 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
3020 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
3022 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
3023 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
3025 #ifdef SSL_OP_EPHEMERAL_RSA
3026 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
3028 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
3029 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
3031 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
3032 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
3034 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
3035 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
3037 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
3038 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
3040 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
3041 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
3043 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
3044 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
3046 #ifdef SSL_OP_NO_COMPRESSION
3047 { US"no_compression", SSL_OP_NO_COMPRESSION },
3049 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
3050 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
3052 #ifdef SSL_OP_NO_SSLv2
3053 { US"no_sslv2", SSL_OP_NO_SSLv2 },
3055 #ifdef SSL_OP_NO_SSLv3
3056 { US"no_sslv3", SSL_OP_NO_SSLv3 },
3058 #ifdef SSL_OP_NO_TICKET
3059 { US"no_ticket", SSL_OP_NO_TICKET },
3061 #ifdef SSL_OP_NO_TLSv1
3062 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
3064 #ifdef SSL_OP_NO_TLSv1_1
3065 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
3066 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
3067 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
3069 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
3072 #ifdef SSL_OP_NO_TLSv1_2
3073 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
3075 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
3076 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
3078 #ifdef SSL_OP_SINGLE_DH_USE
3079 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
3081 #ifdef SSL_OP_SINGLE_ECDH_USE
3082 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
3084 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
3085 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
3087 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
3088 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
3090 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
3091 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
3093 #ifdef SSL_OP_TLS_D5_BUG
3094 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
3096 #ifdef SSL_OP_TLS_ROLLBACK_BUG
3097 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
3100 static int exim_openssl_options_size =
3101 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
3105 tls_openssl_one_option_parse(uschar *name, long *value)
3108 int last = exim_openssl_options_size;
3109 while (last > first)
3111 int middle = (first + last)/2;
3112 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3115 *value = exim_openssl_options[middle].value;
3129 /*************************************************
3130 * OpenSSL option parsing logic *
3131 *************************************************/
3133 /* OpenSSL has a number of compatibility options which an administrator might
3134 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3135 we look like log_selector.
3138 option_spec the administrator-supplied string of options
3139 results ptr to long storage for the options bitmap
3140 Returns success or failure
3144 tls_openssl_options_parse(uschar *option_spec, long *results)
3149 BOOL adding, item_parsed;
3151 result = SSL_OP_NO_TICKET;
3152 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3153 * from default because it increases BEAST susceptibility. */
3154 #ifdef SSL_OP_NO_SSLv2
3155 result |= SSL_OP_NO_SSLv2;
3157 #ifdef SSL_OP_SINGLE_DH_USE
3158 result |= SSL_OP_SINGLE_DH_USE;
3167 for (s=option_spec; *s != '\0'; /**/)
3169 while (isspace(*s)) ++s;
3172 if (*s != '+' && *s != '-')
3174 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3175 "+ or - expected but found \"%s\"\n", s);
3178 adding = *s++ == '+';
3179 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3182 item_parsed = tls_openssl_one_option_parse(s, &item);
3186 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3189 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3190 adding ? "adding" : "removing", result, item, s);
3204 /* End of tls-openssl.c */