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TLS authenticator
[exim.git] / src / src / tls-openssl.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2014 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Portions Copyright (c) The OpenSSL Project 1999 */
9
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.
14
15 No cryptographic code is included in Exim. All this module does is to call
16 functions from the OpenSSL library. */
17
18
19 /* Heading stuff */
20
21 #include <openssl/lhash.h>
22 #include <openssl/ssl.h>
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
25 #ifndef DISABLE_OCSP
26 # include <openssl/ocsp.h>
27 #endif
28 #ifdef EXPERIMENTAL_DANE
29 # include <danessl.h>
30 #endif
31
32
33 #ifndef DISABLE_OCSP
34 # define EXIM_OCSP_SKEW_SECONDS (300L)
35 # define EXIM_OCSP_MAX_AGE (-1L)
36 #endif
37
38 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
39 # define EXIM_HAVE_OPENSSL_TLSEXT
40 #endif
41
42 /*
43 * X509_check_host provides sane certificate hostname checking, but was added
44 * to OpenSSL late, after other projects forked off the code-base. So in
45 * addition to guarding against the base version number, beware that LibreSSL
46 * does not (at this time) support this function.
47 *
48 * If LibreSSL gains a different API, perhaps via libtls, then we'll probably
49 * opt to disentangle and ask a LibreSSL user to provide glue for a third
50 * crypto provider for libtls instead of continuing to tie the OpenSSL glue
51 * into even twistier knots. If LibreSSL gains the same API, we can just
52 * change this guard and punt the issue for a while longer.
53 */
54 #ifndef LIBRESSL_VERSION_NUMBER
55 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
56 # define EXIM_HAVE_OPENSSL_CHECKHOST
57 # endif
58 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
59 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
60 # define EXIM_HAVE_OPENSSL_CHECKHOST
61 # endif
62 #endif
63
64 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
65 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
66 # define DISABLE_OCSP
67 #endif
68
69 /* Structure for collecting random data for seeding. */
70
71 typedef struct randstuff {
72 struct timeval tv;
73 pid_t p;
74 } randstuff;
75
76 /* Local static variables */
77
78 static BOOL client_verify_callback_called = FALSE;
79 static BOOL server_verify_callback_called = FALSE;
80 static const uschar *sid_ctx = US"exim";
81
82 /* We have three different contexts to care about.
83
84 Simple case: client, `client_ctx`
85 As a client, we can be doing a callout or cut-through delivery while receiving
86 a message. So we have a client context, which should have options initialised
87 from the SMTP Transport.
88
89 Server:
90 There are two cases: with and without ServerNameIndication from the client.
91 Given TLS SNI, we can be using different keys, certs and various other
92 configuration settings, because they're re-expanded with $tls_sni set. This
93 allows vhosting with TLS. This SNI is sent in the handshake.
94 A client might not send SNI, so we need a fallback, and an initial setup too.
95 So as a server, we start out using `server_ctx`.
96 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
97 `server_sni` from `server_ctx` and then initialise settings by re-expanding
98 configuration.
99 */
100
101 static SSL_CTX *client_ctx = NULL;
102 static SSL_CTX *server_ctx = NULL;
103 static SSL *client_ssl = NULL;
104 static SSL *server_ssl = NULL;
105
106 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
107 static SSL_CTX *server_sni = NULL;
108 #endif
109
110 static char ssl_errstring[256];
111
112 static int ssl_session_timeout = 200;
113 static BOOL client_verify_optional = FALSE;
114 static BOOL server_verify_optional = FALSE;
115
116 static BOOL reexpand_tls_files_for_sni = FALSE;
117
118
119 typedef struct tls_ext_ctx_cb {
120 uschar *certificate;
121 uschar *privatekey;
122 #ifndef DISABLE_OCSP
123 BOOL is_server;
124 union {
125 struct {
126 uschar *file;
127 uschar *file_expanded;
128 OCSP_RESPONSE *response;
129 } server;
130 struct {
131 X509_STORE *verify_store; /* non-null if status requested */
132 BOOL verify_required;
133 } client;
134 } u_ocsp;
135 #endif
136 uschar *dhparam;
137 /* these are cached from first expand */
138 uschar *server_cipher_list;
139 /* only passed down to tls_error: */
140 host_item *host;
141 const uschar * verify_cert_hostnames;
142 #ifdef EXPERIMENTAL_EVENT
143 uschar * event_action;
144 #endif
145 } tls_ext_ctx_cb;
146
147 /* should figure out a cleanup of API to handle state preserved per
148 implementation, for various reasons, which can be void * in the APIs.
149 For now, we hack around it. */
150 tls_ext_ctx_cb *client_static_cbinfo = NULL;
151 tls_ext_ctx_cb *server_static_cbinfo = NULL;
152
153 static int
154 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
155 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
156
157 /* Callbacks */
158 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
159 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
160 #endif
161 #ifndef DISABLE_OCSP
162 static int tls_server_stapling_cb(SSL *s, void *arg);
163 #endif
164
165
166 /*************************************************
167 * Handle TLS error *
168 *************************************************/
169
170 /* Called from lots of places when errors occur before actually starting to do
171 the TLS handshake, that is, while the session is still in clear. Always returns
172 DEFER for a server and FAIL for a client so that most calls can use "return
173 tls_error(...)" to do this processing and then give an appropriate return. A
174 single function is used for both server and client, because it is called from
175 some shared functions.
176
177 Argument:
178 prefix text to include in the logged error
179 host NULL if setting up a server;
180 the connected host if setting up a client
181 msg error message or NULL if we should ask OpenSSL
182
183 Returns: OK/DEFER/FAIL
184 */
185
186 static int
187 tls_error(uschar * prefix, const host_item * host, uschar * msg)
188 {
189 if (!msg)
190 {
191 ERR_error_string(ERR_get_error(), ssl_errstring);
192 msg = (uschar *)ssl_errstring;
193 }
194
195 if (host)
196 {
197 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
198 host->name, host->address, prefix, msg);
199 return FAIL;
200 }
201 else
202 {
203 uschar *conn_info = smtp_get_connection_info();
204 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
205 conn_info += 5;
206 /* I'd like to get separated H= here, but too hard for now */
207 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
208 conn_info, prefix, msg);
209 return DEFER;
210 }
211 }
212
213
214
215 /*************************************************
216 * Callback to generate RSA key *
217 *************************************************/
218
219 /*
220 Arguments:
221 s SSL connection
222 export not used
223 keylength keylength
224
225 Returns: pointer to generated key
226 */
227
228 static RSA *
229 rsa_callback(SSL *s, int export, int keylength)
230 {
231 RSA *rsa_key;
232 export = export; /* Shut picky compilers up */
233 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
234 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
235 if (rsa_key == NULL)
236 {
237 ERR_error_string(ERR_get_error(), ssl_errstring);
238 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
239 ssl_errstring);
240 return NULL;
241 }
242 return rsa_key;
243 }
244
245
246
247 /* Extreme debug
248 #ifndef DISABLE_OCSP
249 void
250 x509_store_dump_cert_s_names(X509_STORE * store)
251 {
252 STACK_OF(X509_OBJECT) * roots= store->objs;
253 int i;
254 static uschar name[256];
255
256 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
257 {
258 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
259 if(tmp_obj->type == X509_LU_X509)
260 {
261 X509 * current_cert= tmp_obj->data.x509;
262 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
263 name[sizeof(name)-1] = '\0';
264 debug_printf(" %s\n", name);
265 }
266 }
267 }
268 #endif
269 */
270
271
272 #ifdef EXPERIMENTAL_EVENT
273 static int
274 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
275 BOOL *calledp, const BOOL *optionalp, const uschar * what)
276 {
277 uschar * ev;
278 uschar * yield;
279 X509 * old_cert;
280
281 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
282 if (ev)
283 {
284 old_cert = tlsp->peercert;
285 tlsp->peercert = X509_dup(cert);
286 /* NB we do not bother setting peerdn */
287 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
288 {
289 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
290 "depth=%d cert=%s: %s",
291 tlsp == &tls_out ? deliver_host_address : sender_host_address,
292 what, depth, dn, yield);
293 *calledp = TRUE;
294 if (!*optionalp)
295 {
296 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
297 return 1; /* reject (leaving peercert set) */
298 }
299 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
300 "(host in tls_try_verify_hosts)\n");
301 }
302 X509_free(tlsp->peercert);
303 tlsp->peercert = old_cert;
304 }
305 return 0;
306 }
307 #endif
308
309 /*************************************************
310 * Callback for verification *
311 *************************************************/
312
313 /* The SSL library does certificate verification if set up to do so. This
314 callback has the current yes/no state is in "state". If verification succeeded,
315 we set the certificate-verified flag. If verification failed, what happens
316 depends on whether the client is required to present a verifiable certificate
317 or not.
318
319 If verification is optional, we change the state to yes, but still log the
320 verification error. For some reason (it really would help to have proper
321 documentation of OpenSSL), this callback function then gets called again, this
322 time with state = 1. We must take care not to set the private verified flag on
323 the second time through.
324
325 Note: this function is not called if the client fails to present a certificate
326 when asked. We get here only if a certificate has been received. Handling of
327 optional verification for this case is done when requesting SSL to verify, by
328 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
329
330 May be called multiple times for different issues with a certificate, even
331 for a given "depth" in the certificate chain.
332
333 Arguments:
334 state current yes/no state as 1/0
335 x509ctx certificate information.
336 client TRUE for client startup, FALSE for server startup
337
338 Returns: 1 if verified, 0 if not
339 */
340
341 static int
342 verify_callback(int state, X509_STORE_CTX *x509ctx,
343 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
344 {
345 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
346 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
347 uschar dn[256];
348
349 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
350 dn[sizeof(dn)-1] = '\0';
351
352 if (state == 0)
353 {
354 log_write(0, LOG_MAIN, "[%s] SSL verify error: depth=%d error=%s cert=%s",
355 tlsp == &tls_out ? deliver_host_address : sender_host_address,
356 depth,
357 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
358 dn);
359 *calledp = TRUE;
360 if (!*optionalp)
361 {
362 if (!tlsp->peercert)
363 tlsp->peercert = X509_dup(cert); /* record failing cert */
364 return 0; /* reject */
365 }
366 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
367 "tls_try_verify_hosts)\n");
368 }
369
370 else if (depth != 0)
371 {
372 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
373 #ifndef DISABLE_OCSP
374 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
375 { /* client, wanting stapling */
376 /* Add the server cert's signing chain as the one
377 for the verification of the OCSP stapled information. */
378
379 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
380 cert))
381 ERR_clear_error();
382 }
383 #endif
384 #ifdef EXPERIMENTAL_EVENT
385 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
386 return 0; /* reject, with peercert set */
387 #endif
388 }
389 else
390 {
391 const uschar * verify_cert_hostnames;
392
393 if ( tlsp == &tls_out
394 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
395 /* client, wanting hostname check */
396 {
397
398 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
399 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
400 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
401 # endif
402 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
403 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
404 # endif
405 int sep = 0;
406 const uschar * list = verify_cert_hostnames;
407 uschar * name;
408 int rc;
409 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
410 if ((rc = X509_check_host(cert, name, 0,
411 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
412 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
413 NULL)))
414 {
415 if (rc < 0)
416 {
417 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
418 tlsp == &tls_out ? deliver_host_address : sender_host_address);
419 name = NULL;
420 }
421 break;
422 }
423 if (!name)
424 #else
425 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
426 #endif
427 {
428 log_write(0, LOG_MAIN,
429 "[%s] SSL verify error: certificate name mismatch: \"%s\"",
430 tlsp == &tls_out ? deliver_host_address : sender_host_address,
431 dn);
432 *calledp = TRUE;
433 if (!*optionalp)
434 {
435 if (!tlsp->peercert)
436 tlsp->peercert = X509_dup(cert); /* record failing cert */
437 return 0; /* reject */
438 }
439 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
440 "tls_try_verify_hosts)\n");
441 }
442 }
443
444 #ifdef EXPERIMENTAL_EVENT
445 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
446 return 0; /* reject, with peercert set */
447 #endif
448
449 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
450 *calledp ? "" : " authenticated", dn);
451 if (!*calledp) tlsp->certificate_verified = TRUE;
452 *calledp = TRUE;
453 }
454
455 return 1; /* accept, at least for this level */
456 }
457
458 static int
459 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
460 {
461 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
462 }
463
464 static int
465 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
466 {
467 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
468 }
469
470
471 #ifdef EXPERIMENTAL_DANE
472
473 /* This gets called *by* the dane library verify callback, which interposes
474 itself.
475 */
476 static int
477 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
478 {
479 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
480 uschar dn[256];
481 #ifdef EXPERIMENTAL_EVENT
482 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
483 BOOL dummy_called, optional = FALSE;
484 #endif
485
486 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
487 dn[sizeof(dn)-1] = '\0';
488
489 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", dn);
490
491 #ifdef EXPERIMENTAL_EVENT
492 if (verify_event(&tls_out, cert, depth, dn,
493 &dummy_called, &optional, US"DANE"))
494 return 0; /* reject, with peercert set */
495 #endif
496
497 if (state == 1)
498 tls_out.dane_verified =
499 tls_out.certificate_verified = TRUE;
500 return 1;
501 }
502
503 #endif /*EXPERIMENTAL_DANE*/
504
505
506 /*************************************************
507 * Information callback *
508 *************************************************/
509
510 /* The SSL library functions call this from time to time to indicate what they
511 are doing. We copy the string to the debugging output when TLS debugging has
512 been requested.
513
514 Arguments:
515 s the SSL connection
516 where
517 ret
518
519 Returns: nothing
520 */
521
522 static void
523 info_callback(SSL *s, int where, int ret)
524 {
525 where = where;
526 ret = ret;
527 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
528 }
529
530
531
532 /*************************************************
533 * Initialize for DH *
534 *************************************************/
535
536 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
537
538 Arguments:
539 sctx The current SSL CTX (inbound or outbound)
540 dhparam DH parameter file or fixed parameter identity string
541 host connected host, if client; NULL if server
542
543 Returns: TRUE if OK (nothing to set up, or setup worked)
544 */
545
546 static BOOL
547 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host)
548 {
549 BIO *bio;
550 DH *dh;
551 uschar *dhexpanded;
552 const char *pem;
553
554 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
555 return FALSE;
556
557 if (!dhexpanded || !*dhexpanded)
558 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
559 else if (dhexpanded[0] == '/')
560 {
561 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
562 {
563 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
564 host, US strerror(errno));
565 return FALSE;
566 }
567 }
568 else
569 {
570 if (Ustrcmp(dhexpanded, "none") == 0)
571 {
572 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
573 return TRUE;
574 }
575
576 if (!(pem = std_dh_prime_named(dhexpanded)))
577 {
578 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
579 host, US strerror(errno));
580 return FALSE;
581 }
582 bio = BIO_new_mem_buf(CS pem, -1);
583 }
584
585 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
586 {
587 BIO_free(bio);
588 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
589 host, NULL);
590 return FALSE;
591 }
592
593 /* Even if it is larger, we silently return success rather than cause things
594 * to fail out, so that a too-large DH will not knock out all TLS; it's a
595 * debatable choice. */
596 if ((8*DH_size(dh)) > tls_dh_max_bits)
597 {
598 DEBUG(D_tls)
599 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
600 8*DH_size(dh), tls_dh_max_bits);
601 }
602 else
603 {
604 SSL_CTX_set_tmp_dh(sctx, dh);
605 DEBUG(D_tls)
606 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
607 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
608 }
609
610 DH_free(dh);
611 BIO_free(bio);
612
613 return TRUE;
614 }
615
616
617
618
619 /*************************************************
620 * Initialize for ECDH *
621 *************************************************/
622
623 /* Load parameters for ECDH encryption.
624
625 For now, we stick to NIST P-256 because: it's simple and easy to configure;
626 it avoids any patent issues that might bite redistributors; despite events in
627 the news and concerns over curve choices, we're not cryptographers, we're not
628 pretending to be, and this is "good enough" to be better than no support,
629 protecting against most adversaries. Given another year or two, there might
630 be sufficient clarity about a "right" way forward to let us make an informed
631 decision, instead of a knee-jerk reaction.
632
633 Longer-term, we should look at supporting both various named curves and
634 external files generated with "openssl ecparam", much as we do for init_dh().
635 We should also support "none" as a value, to explicitly avoid initialisation.
636
637 Patches welcome.
638
639 Arguments:
640 sctx The current SSL CTX (inbound or outbound)
641 host connected host, if client; NULL if server
642
643 Returns: TRUE if OK (nothing to set up, or setup worked)
644 */
645
646 static BOOL
647 init_ecdh(SSL_CTX *sctx, host_item *host)
648 {
649 if (host) /* No ECDH setup for clients, only for servers */
650 return TRUE;
651
652 #ifndef SSL_CTX_set_tmp_ecdh
653 /* No elliptic curve API in OpenSSL, skip it */
654 DEBUG(D_tls)
655 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
656 return TRUE;
657 #else
658 # ifndef NID_X9_62_prime256v1
659 /* For now, stick to NIST P-256 to get "something" running.
660 If that's not available, bail */
661 DEBUG(D_tls)
662 debug_printf("NIST P-256 EC curve not available, skipping ECDH setup\n");
663 return TRUE;
664 # else
665 {
666 EC_KEY * ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
667 BOOL rv;
668
669 /* The "tmp" in the name here refers to setting a tempoary key
670 not to the stability of the interface. */
671
672 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) != 0))
673 {
674 DEBUG(D_tls) debug_printf("ECDH: enable NIST P-256 curve\n");
675 }
676 else
677 tls_error(US"Error enabling NIST P-256 curve", host, NULL);
678 EC_KEY_free(ecdh);
679 return rv;
680 }
681 # endif
682 #endif
683 }
684
685
686
687
688 #ifndef DISABLE_OCSP
689 /*************************************************
690 * Load OCSP information into state *
691 *************************************************/
692
693 /* Called to load the server OCSP response from the given file into memory, once
694 caller has determined this is needed. Checks validity. Debugs a message
695 if invalid.
696
697 ASSUMES: single response, for single cert.
698
699 Arguments:
700 sctx the SSL_CTX* to update
701 cbinfo various parts of session state
702 expanded the filename putatively holding an OCSP response
703
704 */
705
706 static void
707 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
708 {
709 BIO *bio;
710 OCSP_RESPONSE *resp;
711 OCSP_BASICRESP *basic_response;
712 OCSP_SINGLERESP *single_response;
713 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
714 X509_STORE *store;
715 unsigned long verify_flags;
716 int status, reason, i;
717
718 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
719 if (cbinfo->u_ocsp.server.response)
720 {
721 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
722 cbinfo->u_ocsp.server.response = NULL;
723 }
724
725 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
726 if (!bio)
727 {
728 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
729 cbinfo->u_ocsp.server.file_expanded);
730 return;
731 }
732
733 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
734 BIO_free(bio);
735 if (!resp)
736 {
737 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
738 return;
739 }
740
741 status = OCSP_response_status(resp);
742 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
743 {
744 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
745 OCSP_response_status_str(status), status);
746 goto bad;
747 }
748
749 basic_response = OCSP_response_get1_basic(resp);
750 if (!basic_response)
751 {
752 DEBUG(D_tls)
753 debug_printf("OCSP response parse error: unable to extract basic response.\n");
754 goto bad;
755 }
756
757 store = SSL_CTX_get_cert_store(sctx);
758 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
759
760 /* May need to expose ability to adjust those flags?
761 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
762 OCSP_TRUSTOTHER OCSP_NOINTERN */
763
764 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
765 if (i <= 0)
766 {
767 DEBUG(D_tls) {
768 ERR_error_string(ERR_get_error(), ssl_errstring);
769 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
770 }
771 goto bad;
772 }
773
774 /* Here's the simplifying assumption: there's only one response, for the
775 one certificate we use, and nothing for anything else in a chain. If this
776 proves false, we need to extract a cert id from our issued cert
777 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
778 right cert in the stack and then calls OCSP_single_get0_status()).
779
780 I'm hoping to avoid reworking a bunch more of how we handle state here. */
781 single_response = OCSP_resp_get0(basic_response, 0);
782 if (!single_response)
783 {
784 DEBUG(D_tls)
785 debug_printf("Unable to get first response from OCSP basic response.\n");
786 goto bad;
787 }
788
789 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
790 if (status != V_OCSP_CERTSTATUS_GOOD)
791 {
792 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
793 OCSP_cert_status_str(status), status,
794 OCSP_crl_reason_str(reason), reason);
795 goto bad;
796 }
797
798 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
799 {
800 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
801 goto bad;
802 }
803
804 supply_response:
805 cbinfo->u_ocsp.server.response = resp;
806 return;
807
808 bad:
809 if (running_in_test_harness)
810 {
811 extern char ** environ;
812 uschar ** p;
813 for (p = USS environ; *p != NULL; p++)
814 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
815 {
816 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
817 goto supply_response;
818 }
819 }
820 return;
821 }
822 #endif /*!DISABLE_OCSP*/
823
824
825
826
827 /*************************************************
828 * Expand key and cert file specs *
829 *************************************************/
830
831 /* Called once during tls_init and possibly again during TLS setup, for a
832 new context, if Server Name Indication was used and tls_sni was seen in
833 the certificate string.
834
835 Arguments:
836 sctx the SSL_CTX* to update
837 cbinfo various parts of session state
838
839 Returns: OK/DEFER/FAIL
840 */
841
842 static int
843 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
844 {
845 uschar *expanded;
846
847 if (cbinfo->certificate == NULL)
848 return OK;
849
850 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
851 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
852 Ustrstr(cbinfo->certificate, US"tls_out_sni")
853 )
854 reexpand_tls_files_for_sni = TRUE;
855
856 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
857 return DEFER;
858
859 if (expanded != NULL)
860 {
861 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
862 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
863 return tls_error(string_sprintf(
864 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
865 cbinfo->host, NULL);
866 }
867
868 if (cbinfo->privatekey != NULL &&
869 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
870 return DEFER;
871
872 /* If expansion was forced to fail, key_expanded will be NULL. If the result
873 of the expansion is an empty string, ignore it also, and assume the private
874 key is in the same file as the certificate. */
875
876 if (expanded != NULL && *expanded != 0)
877 {
878 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
879 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
880 return tls_error(string_sprintf(
881 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
882 }
883
884 #ifndef DISABLE_OCSP
885 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
886 {
887 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
888 return DEFER;
889
890 if (expanded != NULL && *expanded != 0)
891 {
892 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
893 if (cbinfo->u_ocsp.server.file_expanded &&
894 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
895 {
896 DEBUG(D_tls)
897 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
898 } else {
899 ocsp_load_response(sctx, cbinfo, expanded);
900 }
901 }
902 }
903 #endif
904
905 return OK;
906 }
907
908
909
910
911 /*************************************************
912 * Callback to handle SNI *
913 *************************************************/
914
915 /* Called when acting as server during the TLS session setup if a Server Name
916 Indication extension was sent by the client.
917
918 API documentation is OpenSSL s_server.c implementation.
919
920 Arguments:
921 s SSL* of the current session
922 ad unknown (part of OpenSSL API) (unused)
923 arg Callback of "our" registered data
924
925 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
926 */
927
928 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
929 static int
930 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
931 {
932 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
933 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
934 int rc;
935 int old_pool = store_pool;
936
937 if (!servername)
938 return SSL_TLSEXT_ERR_OK;
939
940 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
941 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
942
943 /* Make the extension value available for expansion */
944 store_pool = POOL_PERM;
945 tls_in.sni = string_copy(US servername);
946 store_pool = old_pool;
947
948 if (!reexpand_tls_files_for_sni)
949 return SSL_TLSEXT_ERR_OK;
950
951 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
952 not confident that memcpy wouldn't break some internal reference counting.
953 Especially since there's a references struct member, which would be off. */
954
955 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
956 {
957 ERR_error_string(ERR_get_error(), ssl_errstring);
958 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
959 return SSL_TLSEXT_ERR_NOACK;
960 }
961
962 /* Not sure how many of these are actually needed, since SSL object
963 already exists. Might even need this selfsame callback, for reneg? */
964
965 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
966 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
967 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
968 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
969 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
970 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
971
972 if ( !init_dh(server_sni, cbinfo->dhparam, NULL)
973 || !init_ecdh(server_sni, NULL)
974 )
975 return SSL_TLSEXT_ERR_NOACK;
976
977 if (cbinfo->server_cipher_list)
978 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
979 #ifndef DISABLE_OCSP
980 if (cbinfo->u_ocsp.server.file)
981 {
982 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
983 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
984 }
985 #endif
986
987 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
988 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
989
990 /* do this after setup_certs, because this can require the certs for verifying
991 OCSP information. */
992 if ((rc = tls_expand_session_files(server_sni, cbinfo)) != OK)
993 return SSL_TLSEXT_ERR_NOACK;
994
995 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
996 SSL_set_SSL_CTX(s, server_sni);
997
998 return SSL_TLSEXT_ERR_OK;
999 }
1000 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1001
1002
1003
1004
1005 #ifndef DISABLE_OCSP
1006
1007 /*************************************************
1008 * Callback to handle OCSP Stapling *
1009 *************************************************/
1010
1011 /* Called when acting as server during the TLS session setup if the client
1012 requests OCSP information with a Certificate Status Request.
1013
1014 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1015 project.
1016
1017 */
1018
1019 static int
1020 tls_server_stapling_cb(SSL *s, void *arg)
1021 {
1022 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1023 uschar *response_der;
1024 int response_der_len;
1025
1026 DEBUG(D_tls)
1027 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1028 cbinfo->u_ocsp.server.response ? "have" : "lack");
1029
1030 tls_in.ocsp = OCSP_NOT_RESP;
1031 if (!cbinfo->u_ocsp.server.response)
1032 return SSL_TLSEXT_ERR_NOACK;
1033
1034 response_der = NULL;
1035 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
1036 &response_der);
1037 if (response_der_len <= 0)
1038 return SSL_TLSEXT_ERR_NOACK;
1039
1040 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1041 tls_in.ocsp = OCSP_VFIED;
1042 return SSL_TLSEXT_ERR_OK;
1043 }
1044
1045
1046 static void
1047 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1048 {
1049 BIO_printf(bp, "\t%s: ", str);
1050 ASN1_GENERALIZEDTIME_print(bp, time);
1051 BIO_puts(bp, "\n");
1052 }
1053
1054 static int
1055 tls_client_stapling_cb(SSL *s, void *arg)
1056 {
1057 tls_ext_ctx_cb * cbinfo = arg;
1058 const unsigned char * p;
1059 int len;
1060 OCSP_RESPONSE * rsp;
1061 OCSP_BASICRESP * bs;
1062 int i;
1063
1064 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1065 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1066 if(!p)
1067 {
1068 /* Expect this when we requested ocsp but got none */
1069 if ( cbinfo->u_ocsp.client.verify_required
1070 && log_extra_selector & LX_tls_cipher)
1071 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1072 else
1073 DEBUG(D_tls) debug_printf(" null\n");
1074 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1075 }
1076
1077 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1078 {
1079 tls_out.ocsp = OCSP_FAILED;
1080 if (log_extra_selector & LX_tls_cipher)
1081 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1082 else
1083 DEBUG(D_tls) debug_printf(" parse error\n");
1084 return 0;
1085 }
1086
1087 if(!(bs = OCSP_response_get1_basic(rsp)))
1088 {
1089 tls_out.ocsp = OCSP_FAILED;
1090 if (log_extra_selector & LX_tls_cipher)
1091 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1092 else
1093 DEBUG(D_tls) debug_printf(" error parsing response\n");
1094 OCSP_RESPONSE_free(rsp);
1095 return 0;
1096 }
1097
1098 /* We'd check the nonce here if we'd put one in the request. */
1099 /* However that would defeat cacheability on the server so we don't. */
1100
1101 /* This section of code reworked from OpenSSL apps source;
1102 The OpenSSL Project retains copyright:
1103 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1104 */
1105 {
1106 BIO * bp = NULL;
1107 int status, reason;
1108 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1109
1110 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1111
1112 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1113
1114 /* Use the chain that verified the server cert to verify the stapled info */
1115 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1116
1117 if ((i = OCSP_basic_verify(bs, NULL,
1118 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1119 {
1120 tls_out.ocsp = OCSP_FAILED;
1121 if (log_extra_selector & LX_tls_cipher)
1122 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1123 BIO_printf(bp, "OCSP response verify failure\n");
1124 ERR_print_errors(bp);
1125 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1126 goto out;
1127 }
1128
1129 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1130
1131 {
1132 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1133 OCSP_SINGLERESP * single;
1134
1135 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1136 {
1137 tls_out.ocsp = OCSP_FAILED;
1138 log_write(0, LOG_MAIN, "OCSP stapling "
1139 "with multiple responses not handled");
1140 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1141 goto out;
1142 }
1143 single = OCSP_resp_get0(bs, 0);
1144 status = OCSP_single_get0_status(single, &reason, &rev,
1145 &thisupd, &nextupd);
1146 }
1147
1148 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1149 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1150 if (!OCSP_check_validity(thisupd, nextupd,
1151 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1152 {
1153 tls_out.ocsp = OCSP_FAILED;
1154 DEBUG(D_tls) ERR_print_errors(bp);
1155 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1156 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1157 }
1158 else
1159 {
1160 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1161 OCSP_cert_status_str(status));
1162 switch(status)
1163 {
1164 case V_OCSP_CERTSTATUS_GOOD:
1165 tls_out.ocsp = OCSP_VFIED;
1166 i = 1;
1167 break;
1168 case V_OCSP_CERTSTATUS_REVOKED:
1169 tls_out.ocsp = OCSP_FAILED;
1170 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1171 reason != -1 ? "; reason: " : "",
1172 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1173 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1174 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1175 break;
1176 default:
1177 tls_out.ocsp = OCSP_FAILED;
1178 log_write(0, LOG_MAIN,
1179 "Server certificate status unknown, in OCSP stapling");
1180 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1181 break;
1182 }
1183 }
1184 out:
1185 BIO_free(bp);
1186 }
1187
1188 OCSP_RESPONSE_free(rsp);
1189 return i;
1190 }
1191 #endif /*!DISABLE_OCSP*/
1192
1193
1194 /*************************************************
1195 * Initialize for TLS *
1196 *************************************************/
1197
1198 /* Called from both server and client code, to do preliminary initialization
1199 of the library. We allocate and return a context structure.
1200
1201 Arguments:
1202 ctxp returned SSL context
1203 host connected host, if client; NULL if server
1204 dhparam DH parameter file
1205 certificate certificate file
1206 privatekey private key
1207 ocsp_file file of stapling info (server); flag for require ocsp (client)
1208 addr address if client; NULL if server (for some randomness)
1209 cbp place to put allocated callback context
1210
1211 Returns: OK/DEFER/FAIL
1212 */
1213
1214 static int
1215 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1216 uschar *privatekey,
1217 #ifndef DISABLE_OCSP
1218 uschar *ocsp_file,
1219 #endif
1220 address_item *addr, tls_ext_ctx_cb ** cbp)
1221 {
1222 long init_options;
1223 int rc;
1224 BOOL okay;
1225 tls_ext_ctx_cb * cbinfo;
1226
1227 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1228 cbinfo->certificate = certificate;
1229 cbinfo->privatekey = privatekey;
1230 #ifndef DISABLE_OCSP
1231 if ((cbinfo->is_server = host==NULL))
1232 {
1233 cbinfo->u_ocsp.server.file = ocsp_file;
1234 cbinfo->u_ocsp.server.file_expanded = NULL;
1235 cbinfo->u_ocsp.server.response = NULL;
1236 }
1237 else
1238 cbinfo->u_ocsp.client.verify_store = NULL;
1239 #endif
1240 cbinfo->dhparam = dhparam;
1241 cbinfo->server_cipher_list = NULL;
1242 cbinfo->host = host;
1243 #ifdef EXPERIMENTAL_EVENT
1244 cbinfo->event_action = NULL;
1245 #endif
1246
1247 SSL_load_error_strings(); /* basic set up */
1248 OpenSSL_add_ssl_algorithms();
1249
1250 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1251 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1252 list of available digests. */
1253 EVP_add_digest(EVP_sha256());
1254 #endif
1255
1256 /* Create a context.
1257 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1258 negotiation in the different methods; as far as I can tell, the only
1259 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1260 when OpenSSL is built without SSLv2 support.
1261 By disabling with openssl_options, we can let admins re-enable with the
1262 existing knob. */
1263
1264 *ctxp = SSL_CTX_new((host == NULL)?
1265 SSLv23_server_method() : SSLv23_client_method());
1266
1267 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1268
1269 /* It turns out that we need to seed the random number generator this early in
1270 order to get the full complement of ciphers to work. It took me roughly a day
1271 of work to discover this by experiment.
1272
1273 On systems that have /dev/urandom, SSL may automatically seed itself from
1274 there. Otherwise, we have to make something up as best we can. Double check
1275 afterwards. */
1276
1277 if (!RAND_status())
1278 {
1279 randstuff r;
1280 gettimeofday(&r.tv, NULL);
1281 r.p = getpid();
1282
1283 RAND_seed((uschar *)(&r), sizeof(r));
1284 RAND_seed((uschar *)big_buffer, big_buffer_size);
1285 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1286
1287 if (!RAND_status())
1288 return tls_error(US"RAND_status", host,
1289 US"unable to seed random number generator");
1290 }
1291
1292 /* Set up the information callback, which outputs if debugging is at a suitable
1293 level. */
1294
1295 DEBUG(D_tls) SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1296
1297 /* Automatically re-try reads/writes after renegotiation. */
1298 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1299
1300 /* Apply administrator-supplied work-arounds.
1301 Historically we applied just one requested option,
1302 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1303 moved to an administrator-controlled list of options to specify and
1304 grandfathered in the first one as the default value for "openssl_options".
1305
1306 No OpenSSL version number checks: the options we accept depend upon the
1307 availability of the option value macros from OpenSSL. */
1308
1309 okay = tls_openssl_options_parse(openssl_options, &init_options);
1310 if (!okay)
1311 return tls_error(US"openssl_options parsing failed", host, NULL);
1312
1313 if (init_options)
1314 {
1315 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1316 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1317 return tls_error(string_sprintf(
1318 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1319 }
1320 else
1321 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1322
1323 /* Initialize with DH parameters if supplied */
1324
1325 if ( !init_dh(*ctxp, dhparam, host)
1326 || !init_ecdh(*ctxp, host)
1327 )
1328 return DEFER;
1329
1330 /* Set up certificate and key (and perhaps OCSP info) */
1331
1332 rc = tls_expand_session_files(*ctxp, cbinfo);
1333 if (rc != OK) return rc;
1334
1335 /* If we need to handle SNI, do so */
1336 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1337 if (host == NULL) /* server */
1338 {
1339 # ifndef DISABLE_OCSP
1340 /* We check u_ocsp.server.file, not server.response, because we care about if
1341 the option exists, not what the current expansion might be, as SNI might
1342 change the certificate and OCSP file in use between now and the time the
1343 callback is invoked. */
1344 if (cbinfo->u_ocsp.server.file)
1345 {
1346 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1347 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1348 }
1349 # endif
1350 /* We always do this, so that $tls_sni is available even if not used in
1351 tls_certificate */
1352 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1353 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1354 }
1355 # ifndef DISABLE_OCSP
1356 else /* client */
1357 if(ocsp_file) /* wanting stapling */
1358 {
1359 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1360 {
1361 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1362 return FAIL;
1363 }
1364 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1365 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1366 }
1367 # endif
1368 #endif
1369
1370 cbinfo->verify_cert_hostnames = NULL;
1371
1372 /* Set up the RSA callback */
1373
1374 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1375
1376 /* Finally, set the timeout, and we are done */
1377
1378 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1379 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1380
1381 *cbp = cbinfo;
1382
1383 return OK;
1384 }
1385
1386
1387
1388
1389 /*************************************************
1390 * Get name of cipher in use *
1391 *************************************************/
1392
1393 /*
1394 Argument: pointer to an SSL structure for the connection
1395 buffer to use for answer
1396 size of buffer
1397 pointer to number of bits for cipher
1398 Returns: nothing
1399 */
1400
1401 static void
1402 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1403 {
1404 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1405 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1406 the accessor functions use const in the prototype. */
1407 const SSL_CIPHER *c;
1408 const uschar *ver;
1409
1410 ver = (const uschar *)SSL_get_version(ssl);
1411
1412 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1413 SSL_CIPHER_get_bits(c, bits);
1414
1415 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1416 SSL_CIPHER_get_name(c), *bits);
1417
1418 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1419 }
1420
1421
1422 static void
1423 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1424 {
1425 /*XXX we might consider a list-of-certs variable for the cert chain.
1426 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1427 in list-handling functions, also consider the difference between the entire
1428 chain and the elements sent by the peer. */
1429
1430 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1431 if (!tlsp->peercert)
1432 tlsp->peercert = SSL_get_peer_certificate(ssl);
1433 /* Beware anonymous ciphers which lead to server_cert being NULL */
1434 if (tlsp->peercert)
1435 {
1436 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1437 peerdn[bsize-1] = '\0';
1438 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1439 }
1440 else
1441 tlsp->peerdn = NULL;
1442 }
1443
1444
1445
1446
1447
1448 /*************************************************
1449 * Set up for verifying certificates *
1450 *************************************************/
1451
1452 /* Called by both client and server startup
1453
1454 Arguments:
1455 sctx SSL_CTX* to initialise
1456 certs certs file or NULL
1457 crl CRL file or NULL
1458 host NULL in a server; the remote host in a client
1459 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1460 otherwise passed as FALSE
1461 cert_vfy_cb Callback function for certificate verification
1462
1463 Returns: OK/DEFER/FAIL
1464 */
1465
1466 static int
1467 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1468 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1469 {
1470 uschar *expcerts, *expcrl;
1471
1472 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1473 return DEFER;
1474
1475 if (expcerts != NULL && *expcerts != '\0')
1476 {
1477 if (Ustrcmp(expcerts, "system") == 0)
1478 {
1479 /* Tell the library to use its compiled-in location for the system default
1480 CA bundle, only */
1481
1482 if (!SSL_CTX_set_default_verify_paths(sctx))
1483 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1484 }
1485 else
1486 {
1487 struct stat statbuf;
1488
1489 /* Tell the library to use its compiled-in location for the system default
1490 CA bundle. Those given by the exim config are additional to these */
1491
1492 if (!SSL_CTX_set_default_verify_paths(sctx))
1493 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1494
1495 if (Ustat(expcerts, &statbuf) < 0)
1496 {
1497 log_write(0, LOG_MAIN|LOG_PANIC,
1498 "failed to stat %s for certificates", expcerts);
1499 return DEFER;
1500 }
1501 else
1502 {
1503 uschar *file, *dir;
1504 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1505 { file = NULL; dir = expcerts; }
1506 else
1507 { file = expcerts; dir = NULL; }
1508
1509 /* If a certificate file is empty, the next function fails with an
1510 unhelpful error message. If we skip it, we get the correct behaviour (no
1511 certificates are recognized, but the error message is still misleading (it
1512 says no certificate was supplied.) But this is better. */
1513
1514 if ((file == NULL || statbuf.st_size > 0) &&
1515 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1516 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1517
1518 /* Load the list of CAs for which we will accept certs, for sending
1519 to the client. This is only for the one-file tls_verify_certificates
1520 variant.
1521 If a list isn't loaded into the server, but
1522 some verify locations are set, the server end appears to make
1523 a wildcard reqest for client certs.
1524 Meanwhile, the client library as deafult behaviour *ignores* the list
1525 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1526 Because of this, and that the dir variant is likely only used for
1527 the public-CA bundle (not for a private CA), not worth fixing.
1528 */
1529 if (file != NULL)
1530 {
1531 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1532 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1533 sk_X509_NAME_num(names));
1534 SSL_CTX_set_client_CA_list(sctx, names);
1535 }
1536 }
1537 }
1538
1539 /* Handle a certificate revocation list. */
1540
1541 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1542
1543 /* This bit of code is now the version supplied by Lars Mainka. (I have
1544 * merely reformatted it into the Exim code style.)
1545
1546 * "From here I changed the code to add support for multiple crl's
1547 * in pem format in one file or to support hashed directory entries in
1548 * pem format instead of a file. This method now uses the library function
1549 * X509_STORE_load_locations to add the CRL location to the SSL context.
1550 * OpenSSL will then handle the verify against CA certs and CRLs by
1551 * itself in the verify callback." */
1552
1553 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1554 if (expcrl != NULL && *expcrl != 0)
1555 {
1556 struct stat statbufcrl;
1557 if (Ustat(expcrl, &statbufcrl) < 0)
1558 {
1559 log_write(0, LOG_MAIN|LOG_PANIC,
1560 "failed to stat %s for certificates revocation lists", expcrl);
1561 return DEFER;
1562 }
1563 else
1564 {
1565 /* is it a file or directory? */
1566 uschar *file, *dir;
1567 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1568 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1569 {
1570 file = NULL;
1571 dir = expcrl;
1572 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1573 }
1574 else
1575 {
1576 file = expcrl;
1577 dir = NULL;
1578 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1579 }
1580 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1581 return tls_error(US"X509_STORE_load_locations", host, NULL);
1582
1583 /* setting the flags to check against the complete crl chain */
1584
1585 X509_STORE_set_flags(cvstore,
1586 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1587 }
1588 }
1589
1590 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1591
1592 /* If verification is optional, don't fail if no certificate */
1593
1594 SSL_CTX_set_verify(sctx,
1595 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1596 cert_vfy_cb);
1597 }
1598
1599 return OK;
1600 }
1601
1602
1603
1604 /*************************************************
1605 * Start a TLS session in a server *
1606 *************************************************/
1607
1608 /* This is called when Exim is running as a server, after having received
1609 the STARTTLS command. It must respond to that command, and then negotiate
1610 a TLS session.
1611
1612 Arguments:
1613 require_ciphers allowed ciphers
1614
1615 Returns: OK on success
1616 DEFER for errors before the start of the negotiation
1617 FAIL for errors during the negotation; the server can't
1618 continue running.
1619 */
1620
1621 int
1622 tls_server_start(const uschar *require_ciphers)
1623 {
1624 int rc;
1625 uschar *expciphers;
1626 tls_ext_ctx_cb *cbinfo;
1627 static uschar peerdn[256];
1628 static uschar cipherbuf[256];
1629
1630 /* Check for previous activation */
1631
1632 if (tls_in.active >= 0)
1633 {
1634 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1635 smtp_printf("554 Already in TLS\r\n");
1636 return FAIL;
1637 }
1638
1639 /* Initialize the SSL library. If it fails, it will already have logged
1640 the error. */
1641
1642 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1643 #ifndef DISABLE_OCSP
1644 tls_ocsp_file,
1645 #endif
1646 NULL, &server_static_cbinfo);
1647 if (rc != OK) return rc;
1648 cbinfo = server_static_cbinfo;
1649
1650 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1651 return FAIL;
1652
1653 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1654 were historically separated by underscores. So that I can use either form in my
1655 tests, and also for general convenience, we turn underscores into hyphens here.
1656 */
1657
1658 if (expciphers != NULL)
1659 {
1660 uschar *s = expciphers;
1661 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1662 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1663 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1664 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1665 cbinfo->server_cipher_list = expciphers;
1666 }
1667
1668 /* If this is a host for which certificate verification is mandatory or
1669 optional, set up appropriately. */
1670
1671 tls_in.certificate_verified = FALSE;
1672 #ifdef EXPERIMENTAL_DANE
1673 tls_in.dane_verified = FALSE;
1674 #endif
1675 server_verify_callback_called = FALSE;
1676
1677 if (verify_check_host(&tls_verify_hosts) == OK)
1678 {
1679 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1680 FALSE, verify_callback_server);
1681 if (rc != OK) return rc;
1682 server_verify_optional = FALSE;
1683 }
1684 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1685 {
1686 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1687 TRUE, verify_callback_server);
1688 if (rc != OK) return rc;
1689 server_verify_optional = TRUE;
1690 }
1691
1692 /* Prepare for new connection */
1693
1694 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1695
1696 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1697 *
1698 * With the SSL_clear(), we get strange interoperability bugs with
1699 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1700 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1701 *
1702 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1703 * session shutdown. In this case, we have a brand new object and there's no
1704 * obvious reason to immediately clear it. I'm guessing that this was
1705 * originally added because of incomplete initialisation which the clear fixed,
1706 * in some historic release.
1707 */
1708
1709 /* Set context and tell client to go ahead, except in the case of TLS startup
1710 on connection, where outputting anything now upsets the clients and tends to
1711 make them disconnect. We need to have an explicit fflush() here, to force out
1712 the response. Other smtp_printf() calls do not need it, because in non-TLS
1713 mode, the fflush() happens when smtp_getc() is called. */
1714
1715 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1716 if (!tls_in.on_connect)
1717 {
1718 smtp_printf("220 TLS go ahead\r\n");
1719 fflush(smtp_out);
1720 }
1721
1722 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1723 that the OpenSSL library doesn't. */
1724
1725 SSL_set_wfd(server_ssl, fileno(smtp_out));
1726 SSL_set_rfd(server_ssl, fileno(smtp_in));
1727 SSL_set_accept_state(server_ssl);
1728
1729 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1730
1731 sigalrm_seen = FALSE;
1732 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1733 rc = SSL_accept(server_ssl);
1734 alarm(0);
1735
1736 if (rc <= 0)
1737 {
1738 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1739 if (ERR_get_error() == 0)
1740 log_write(0, LOG_MAIN,
1741 "TLS client disconnected cleanly (rejected our certificate?)");
1742 return FAIL;
1743 }
1744
1745 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1746
1747 /* TLS has been set up. Adjust the input functions to read via TLS,
1748 and initialize things. */
1749
1750 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
1751
1752 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1753 tls_in.cipher = cipherbuf;
1754
1755 DEBUG(D_tls)
1756 {
1757 uschar buf[2048];
1758 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1759 debug_printf("Shared ciphers: %s\n", buf);
1760 }
1761
1762 /* Record the certificate we presented */
1763 {
1764 X509 * crt = SSL_get_certificate(server_ssl);
1765 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1766 }
1767
1768 /* Only used by the server-side tls (tls_in), including tls_getc.
1769 Client-side (tls_out) reads (seem to?) go via
1770 smtp_read_response()/ip_recv().
1771 Hence no need to duplicate for _in and _out.
1772 */
1773 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1774 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1775 ssl_xfer_eof = ssl_xfer_error = 0;
1776
1777 receive_getc = tls_getc;
1778 receive_ungetc = tls_ungetc;
1779 receive_feof = tls_feof;
1780 receive_ferror = tls_ferror;
1781 receive_smtp_buffered = tls_smtp_buffered;
1782
1783 tls_in.active = fileno(smtp_out);
1784 return OK;
1785 }
1786
1787
1788
1789
1790 static int
1791 tls_client_basic_ctx_init(SSL_CTX * ctx,
1792 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
1793 )
1794 {
1795 int rc;
1796 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1797 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1798 the specified host patterns if one of them is defined */
1799
1800 if ( ( !ob->tls_verify_hosts
1801 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
1802 )
1803 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
1804 )
1805 client_verify_optional = FALSE;
1806 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1807 client_verify_optional = TRUE;
1808 else
1809 return OK;
1810
1811 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1812 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1813 return rc;
1814
1815 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1816 {
1817 cbinfo->verify_cert_hostnames =
1818 #ifdef EXPERIMENTAL_INTERNATIONAL
1819 string_domain_utf8_to_alabel(host->name, NULL);
1820 #else
1821 host->name;
1822 #endif
1823 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1824 cbinfo->verify_cert_hostnames);
1825 }
1826 return OK;
1827 }
1828
1829
1830 #ifdef EXPERIMENTAL_DANE
1831 static int
1832 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1833 {
1834 dns_record * rr;
1835 dns_scan dnss;
1836 const char * hostnames[2] = { CS host->name, NULL };
1837 int found = 0;
1838
1839 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1840 return tls_error(US"hostnames load", host, NULL);
1841
1842 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1843 rr;
1844 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1845 ) if (rr->type == T_TLSA)
1846 {
1847 uschar * p = rr->data;
1848 uint8_t usage, selector, mtype;
1849 const char * mdname;
1850
1851 usage = *p++;
1852
1853 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1854 if (usage != 2 && usage != 3) continue;
1855
1856 selector = *p++;
1857 mtype = *p++;
1858
1859 switch (mtype)
1860 {
1861 default: continue; /* Only match-types 0, 1, 2 are supported */
1862 case 0: mdname = NULL; break;
1863 case 1: mdname = "sha256"; break;
1864 case 2: mdname = "sha512"; break;
1865 }
1866
1867 found++;
1868 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1869 {
1870 default:
1871 case 0: /* action not taken */
1872 return tls_error(US"tlsa load", host, NULL);
1873 case 1: break;
1874 }
1875
1876 tls_out.tlsa_usage |= 1<<usage;
1877 }
1878
1879 if (found)
1880 return OK;
1881
1882 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1883 return DEFER;
1884 }
1885 #endif /*EXPERIMENTAL_DANE*/
1886
1887
1888
1889 /*************************************************
1890 * Start a TLS session in a client *
1891 *************************************************/
1892
1893 /* Called from the smtp transport after STARTTLS has been accepted.
1894
1895 Argument:
1896 fd the fd of the connection
1897 host connected host (for messages)
1898 addr the first address
1899 tb transport (always smtp)
1900 tlsa_dnsa tlsa lookup, if DANE, else null
1901
1902 Returns: OK on success
1903 FAIL otherwise - note that tls_error() will not give DEFER
1904 because this is not a server
1905 */
1906
1907 int
1908 tls_client_start(int fd, host_item *host, address_item *addr,
1909 transport_instance *tb
1910 #ifdef EXPERIMENTAL_DANE
1911 , dns_answer * tlsa_dnsa
1912 #endif
1913 )
1914 {
1915 smtp_transport_options_block * ob =
1916 (smtp_transport_options_block *)tb->options_block;
1917 static uschar peerdn[256];
1918 uschar * expciphers;
1919 int rc;
1920 static uschar cipherbuf[256];
1921
1922 #ifndef DISABLE_OCSP
1923 BOOL request_ocsp = FALSE;
1924 BOOL require_ocsp = FALSE;
1925 #endif
1926
1927 #ifdef EXPERIMENTAL_DANE
1928 tls_out.tlsa_usage = 0;
1929 #endif
1930
1931 #ifndef DISABLE_OCSP
1932 {
1933 # ifdef EXPERIMENTAL_DANE
1934 if ( tlsa_dnsa
1935 && ob->hosts_request_ocsp[0] == '*'
1936 && ob->hosts_request_ocsp[1] == '\0'
1937 )
1938 {
1939 /* Unchanged from default. Use a safer one under DANE */
1940 request_ocsp = TRUE;
1941 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1942 " {= {4}{$tls_out_tlsa_usage}} } "
1943 " {*}{}}";
1944 }
1945 # endif
1946
1947 if ((require_ocsp =
1948 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
1949 request_ocsp = TRUE;
1950 else
1951 # ifdef EXPERIMENTAL_DANE
1952 if (!request_ocsp)
1953 # endif
1954 request_ocsp =
1955 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1956 }
1957 #endif
1958
1959 rc = tls_init(&client_ctx, host, NULL,
1960 ob->tls_certificate, ob->tls_privatekey,
1961 #ifndef DISABLE_OCSP
1962 (void *)(long)request_ocsp,
1963 #endif
1964 addr, &client_static_cbinfo);
1965 if (rc != OK) return rc;
1966
1967 tls_out.certificate_verified = FALSE;
1968 client_verify_callback_called = FALSE;
1969
1970 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1971 &expciphers))
1972 return FAIL;
1973
1974 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1975 are separated by underscores. So that I can use either form in my tests, and
1976 also for general convenience, we turn underscores into hyphens here. */
1977
1978 if (expciphers != NULL)
1979 {
1980 uschar *s = expciphers;
1981 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1982 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1983 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1984 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1985 }
1986
1987 #ifdef EXPERIMENTAL_DANE
1988 if (tlsa_dnsa)
1989 {
1990 SSL_CTX_set_verify(client_ctx,
1991 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1992 verify_callback_client_dane);
1993
1994 if (!DANESSL_library_init())
1995 return tls_error(US"library init", host, NULL);
1996 if (DANESSL_CTX_init(client_ctx) <= 0)
1997 return tls_error(US"context init", host, NULL);
1998 }
1999 else
2000
2001 #endif
2002
2003 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
2004 != OK)
2005 return rc;
2006
2007 if ((client_ssl = SSL_new(client_ctx)) == NULL)
2008 return tls_error(US"SSL_new", host, NULL);
2009 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
2010 SSL_set_fd(client_ssl, fd);
2011 SSL_set_connect_state(client_ssl);
2012
2013 if (ob->tls_sni)
2014 {
2015 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
2016 return FAIL;
2017 if (tls_out.sni == NULL)
2018 {
2019 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2020 }
2021 else if (!Ustrlen(tls_out.sni))
2022 tls_out.sni = NULL;
2023 else
2024 {
2025 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2026 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
2027 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
2028 #else
2029 DEBUG(D_tls)
2030 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
2031 tls_out.sni);
2032 #endif
2033 }
2034 }
2035
2036 #ifdef EXPERIMENTAL_DANE
2037 if (tlsa_dnsa)
2038 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
2039 return rc;
2040 #endif
2041
2042 #ifndef DISABLE_OCSP
2043 /* Request certificate status at connection-time. If the server
2044 does OCSP stapling we will get the callback (set in tls_init()) */
2045 # ifdef EXPERIMENTAL_DANE
2046 if (request_ocsp)
2047 {
2048 const uschar * s;
2049 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2050 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2051 )
2052 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2053 this means we avoid the OCSP request, we wasted the setup
2054 cost in tls_init(). */
2055 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2056 request_ocsp = require_ocsp
2057 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2058 }
2059 }
2060 # endif
2061
2062 if (request_ocsp)
2063 {
2064 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
2065 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2066 tls_out.ocsp = OCSP_NOT_RESP;
2067 }
2068 #endif
2069
2070 #ifdef EXPERIMENTAL_EVENT
2071 client_static_cbinfo->event_action = tb->event_action;
2072 #endif
2073
2074 /* There doesn't seem to be a built-in timeout on connection. */
2075
2076 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2077 sigalrm_seen = FALSE;
2078 alarm(ob->command_timeout);
2079 rc = SSL_connect(client_ssl);
2080 alarm(0);
2081
2082 #ifdef EXPERIMENTAL_DANE
2083 if (tlsa_dnsa)
2084 DANESSL_cleanup(client_ssl);
2085 #endif
2086
2087 if (rc <= 0)
2088 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
2089
2090 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2091
2092 peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
2093
2094 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2095 tls_out.cipher = cipherbuf;
2096
2097 /* Record the certificate we presented */
2098 {
2099 X509 * crt = SSL_get_certificate(client_ssl);
2100 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2101 }
2102
2103 tls_out.active = fd;
2104 return OK;
2105 }
2106
2107
2108
2109
2110
2111 /*************************************************
2112 * TLS version of getc *
2113 *************************************************/
2114
2115 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2116 it refills the buffer via the SSL reading function.
2117
2118 Arguments: none
2119 Returns: the next character or EOF
2120
2121 Only used by the server-side TLS.
2122 */
2123
2124 int
2125 tls_getc(void)
2126 {
2127 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2128 {
2129 int error;
2130 int inbytes;
2131
2132 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2133 ssl_xfer_buffer, ssl_xfer_buffer_size);
2134
2135 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2136 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2137 error = SSL_get_error(server_ssl, inbytes);
2138 alarm(0);
2139
2140 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2141 closed down, not that the socket itself has been closed down. Revert to
2142 non-SSL handling. */
2143
2144 if (error == SSL_ERROR_ZERO_RETURN)
2145 {
2146 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2147
2148 receive_getc = smtp_getc;
2149 receive_ungetc = smtp_ungetc;
2150 receive_feof = smtp_feof;
2151 receive_ferror = smtp_ferror;
2152 receive_smtp_buffered = smtp_buffered;
2153
2154 SSL_free(server_ssl);
2155 server_ssl = NULL;
2156 tls_in.active = -1;
2157 tls_in.bits = 0;
2158 tls_in.cipher = NULL;
2159 tls_in.peerdn = NULL;
2160 tls_in.sni = NULL;
2161
2162 return smtp_getc();
2163 }
2164
2165 /* Handle genuine errors */
2166
2167 else if (error == SSL_ERROR_SSL)
2168 {
2169 ERR_error_string(ERR_get_error(), ssl_errstring);
2170 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2171 ssl_xfer_error = 1;
2172 return EOF;
2173 }
2174
2175 else if (error != SSL_ERROR_NONE)
2176 {
2177 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2178 ssl_xfer_error = 1;
2179 return EOF;
2180 }
2181
2182 #ifndef DISABLE_DKIM
2183 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2184 #endif
2185 ssl_xfer_buffer_hwm = inbytes;
2186 ssl_xfer_buffer_lwm = 0;
2187 }
2188
2189 /* Something in the buffer; return next uschar */
2190
2191 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2192 }
2193
2194
2195
2196 /*************************************************
2197 * Read bytes from TLS channel *
2198 *************************************************/
2199
2200 /*
2201 Arguments:
2202 buff buffer of data
2203 len size of buffer
2204
2205 Returns: the number of bytes read
2206 -1 after a failed read
2207
2208 Only used by the client-side TLS.
2209 */
2210
2211 int
2212 tls_read(BOOL is_server, uschar *buff, size_t len)
2213 {
2214 SSL *ssl = is_server ? server_ssl : client_ssl;
2215 int inbytes;
2216 int error;
2217
2218 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2219 buff, (unsigned int)len);
2220
2221 inbytes = SSL_read(ssl, CS buff, len);
2222 error = SSL_get_error(ssl, inbytes);
2223
2224 if (error == SSL_ERROR_ZERO_RETURN)
2225 {
2226 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2227 return -1;
2228 }
2229 else if (error != SSL_ERROR_NONE)
2230 {
2231 return -1;
2232 }
2233
2234 return inbytes;
2235 }
2236
2237
2238
2239
2240
2241 /*************************************************
2242 * Write bytes down TLS channel *
2243 *************************************************/
2244
2245 /*
2246 Arguments:
2247 is_server channel specifier
2248 buff buffer of data
2249 len number of bytes
2250
2251 Returns: the number of bytes after a successful write,
2252 -1 after a failed write
2253
2254 Used by both server-side and client-side TLS.
2255 */
2256
2257 int
2258 tls_write(BOOL is_server, const uschar *buff, size_t len)
2259 {
2260 int outbytes;
2261 int error;
2262 int left = len;
2263 SSL *ssl = is_server ? server_ssl : client_ssl;
2264
2265 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2266 while (left > 0)
2267 {
2268 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2269 outbytes = SSL_write(ssl, CS buff, left);
2270 error = SSL_get_error(ssl, outbytes);
2271 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2272 switch (error)
2273 {
2274 case SSL_ERROR_SSL:
2275 ERR_error_string(ERR_get_error(), ssl_errstring);
2276 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2277 return -1;
2278
2279 case SSL_ERROR_NONE:
2280 left -= outbytes;
2281 buff += outbytes;
2282 break;
2283
2284 case SSL_ERROR_ZERO_RETURN:
2285 log_write(0, LOG_MAIN, "SSL channel closed on write");
2286 return -1;
2287
2288 case SSL_ERROR_SYSCALL:
2289 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2290 sender_fullhost ? sender_fullhost : US"<unknown>",
2291 strerror(errno));
2292
2293 default:
2294 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2295 return -1;
2296 }
2297 }
2298 return len;
2299 }
2300
2301
2302
2303 /*************************************************
2304 * Close down a TLS session *
2305 *************************************************/
2306
2307 /* This is also called from within a delivery subprocess forked from the
2308 daemon, to shut down the TLS library, without actually doing a shutdown (which
2309 would tamper with the SSL session in the parent process).
2310
2311 Arguments: TRUE if SSL_shutdown is to be called
2312 Returns: nothing
2313
2314 Used by both server-side and client-side TLS.
2315 */
2316
2317 void
2318 tls_close(BOOL is_server, BOOL shutdown)
2319 {
2320 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2321 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2322
2323 if (*fdp < 0) return; /* TLS was not active */
2324
2325 if (shutdown)
2326 {
2327 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2328 SSL_shutdown(*sslp);
2329 }
2330
2331 SSL_free(*sslp);
2332 *sslp = NULL;
2333
2334 *fdp = -1;
2335 }
2336
2337
2338
2339
2340 /*************************************************
2341 * Let tls_require_ciphers be checked at startup *
2342 *************************************************/
2343
2344 /* The tls_require_ciphers option, if set, must be something which the
2345 library can parse.
2346
2347 Returns: NULL on success, or error message
2348 */
2349
2350 uschar *
2351 tls_validate_require_cipher(void)
2352 {
2353 SSL_CTX *ctx;
2354 uschar *s, *expciphers, *err;
2355
2356 /* this duplicates from tls_init(), we need a better "init just global
2357 state, for no specific purpose" singleton function of our own */
2358
2359 SSL_load_error_strings();
2360 OpenSSL_add_ssl_algorithms();
2361 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2362 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2363 list of available digests. */
2364 EVP_add_digest(EVP_sha256());
2365 #endif
2366
2367 if (!(tls_require_ciphers && *tls_require_ciphers))
2368 return NULL;
2369
2370 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2371 return US"failed to expand tls_require_ciphers";
2372
2373 if (!(expciphers && *expciphers))
2374 return NULL;
2375
2376 /* normalisation ripped from above */
2377 s = expciphers;
2378 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2379
2380 err = NULL;
2381
2382 ctx = SSL_CTX_new(SSLv23_server_method());
2383 if (!ctx)
2384 {
2385 ERR_error_string(ERR_get_error(), ssl_errstring);
2386 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2387 }
2388
2389 DEBUG(D_tls)
2390 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2391
2392 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2393 {
2394 ERR_error_string(ERR_get_error(), ssl_errstring);
2395 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2396 }
2397
2398 SSL_CTX_free(ctx);
2399
2400 return err;
2401 }
2402
2403
2404
2405
2406 /*************************************************
2407 * Report the library versions. *
2408 *************************************************/
2409
2410 /* There have historically been some issues with binary compatibility in
2411 OpenSSL libraries; if Exim (like many other applications) is built against
2412 one version of OpenSSL but the run-time linker picks up another version,
2413 it can result in serious failures, including crashing with a SIGSEGV. So
2414 report the version found by the compiler and the run-time version.
2415
2416 Note: some OS vendors backport security fixes without changing the version
2417 number/string, and the version date remains unchanged. The _build_ date
2418 will change, so we can more usefully assist with version diagnosis by also
2419 reporting the build date.
2420
2421 Arguments: a FILE* to print the results to
2422 Returns: nothing
2423 */
2424
2425 void
2426 tls_version_report(FILE *f)
2427 {
2428 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2429 " Runtime: %s\n"
2430 " : %s\n",
2431 OPENSSL_VERSION_TEXT,
2432 SSLeay_version(SSLEAY_VERSION),
2433 SSLeay_version(SSLEAY_BUILT_ON));
2434 /* third line is 38 characters for the %s and the line is 73 chars long;
2435 the OpenSSL output includes a "built on: " prefix already. */
2436 }
2437
2438
2439
2440
2441 /*************************************************
2442 * Random number generation *
2443 *************************************************/
2444
2445 /* Pseudo-random number generation. The result is not expected to be
2446 cryptographically strong but not so weak that someone will shoot themselves
2447 in the foot using it as a nonce in input in some email header scheme or
2448 whatever weirdness they'll twist this into. The result should handle fork()
2449 and avoid repeating sequences. OpenSSL handles that for us.
2450
2451 Arguments:
2452 max range maximum
2453 Returns a random number in range [0, max-1]
2454 */
2455
2456 int
2457 vaguely_random_number(int max)
2458 {
2459 unsigned int r;
2460 int i, needed_len;
2461 static pid_t pidlast = 0;
2462 pid_t pidnow;
2463 uschar *p;
2464 uschar smallbuf[sizeof(r)];
2465
2466 if (max <= 1)
2467 return 0;
2468
2469 pidnow = getpid();
2470 if (pidnow != pidlast)
2471 {
2472 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2473 is unique for each thread", this doesn't apparently apply across processes,
2474 so our own warning from vaguely_random_number_fallback() applies here too.
2475 Fix per PostgreSQL. */
2476 if (pidlast != 0)
2477 RAND_cleanup();
2478 pidlast = pidnow;
2479 }
2480
2481 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2482 if (!RAND_status())
2483 {
2484 randstuff r;
2485 gettimeofday(&r.tv, NULL);
2486 r.p = getpid();
2487
2488 RAND_seed((uschar *)(&r), sizeof(r));
2489 }
2490 /* We're after pseudo-random, not random; if we still don't have enough data
2491 in the internal PRNG then our options are limited. We could sleep and hope
2492 for entropy to come along (prayer technique) but if the system is so depleted
2493 in the first place then something is likely to just keep taking it. Instead,
2494 we'll just take whatever little bit of pseudo-random we can still manage to
2495 get. */
2496
2497 needed_len = sizeof(r);
2498 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2499 asked for a number less than 10. */
2500 for (r = max, i = 0; r; ++i)
2501 r >>= 1;
2502 i = (i + 7) / 8;
2503 if (i < needed_len)
2504 needed_len = i;
2505
2506 /* We do not care if crypto-strong */
2507 i = RAND_pseudo_bytes(smallbuf, needed_len);
2508 if (i < 0)
2509 {
2510 DEBUG(D_all)
2511 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2512 return vaguely_random_number_fallback(max);
2513 }
2514
2515 r = 0;
2516 for (p = smallbuf; needed_len; --needed_len, ++p)
2517 {
2518 r *= 256;
2519 r += *p;
2520 }
2521
2522 /* We don't particularly care about weighted results; if someone wants
2523 smooth distribution and cares enough then they should submit a patch then. */
2524 return r % max;
2525 }
2526
2527
2528
2529
2530 /*************************************************
2531 * OpenSSL option parse *
2532 *************************************************/
2533
2534 /* Parse one option for tls_openssl_options_parse below
2535
2536 Arguments:
2537 name one option name
2538 value place to store a value for it
2539 Returns success or failure in parsing
2540 */
2541
2542 struct exim_openssl_option {
2543 uschar *name;
2544 long value;
2545 };
2546 /* We could use a macro to expand, but we need the ifdef and not all the
2547 options document which version they were introduced in. Policylet: include
2548 all options unless explicitly for DTLS, let the administrator choose which
2549 to apply.
2550
2551 This list is current as of:
2552 ==> 1.0.1b <==
2553 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2554 */
2555 static struct exim_openssl_option exim_openssl_options[] = {
2556 /* KEEP SORTED ALPHABETICALLY! */
2557 #ifdef SSL_OP_ALL
2558 { US"all", SSL_OP_ALL },
2559 #endif
2560 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2561 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2562 #endif
2563 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2564 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2565 #endif
2566 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2567 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2568 #endif
2569 #ifdef SSL_OP_EPHEMERAL_RSA
2570 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2571 #endif
2572 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2573 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2574 #endif
2575 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2576 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2577 #endif
2578 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2579 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2580 #endif
2581 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2582 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2583 #endif
2584 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2585 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2586 #endif
2587 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2588 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2589 #endif
2590 #ifdef SSL_OP_NO_COMPRESSION
2591 { US"no_compression", SSL_OP_NO_COMPRESSION },
2592 #endif
2593 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2594 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2595 #endif
2596 #ifdef SSL_OP_NO_SSLv2
2597 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2598 #endif
2599 #ifdef SSL_OP_NO_SSLv3
2600 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2601 #endif
2602 #ifdef SSL_OP_NO_TICKET
2603 { US"no_ticket", SSL_OP_NO_TICKET },
2604 #endif
2605 #ifdef SSL_OP_NO_TLSv1
2606 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2607 #endif
2608 #ifdef SSL_OP_NO_TLSv1_1
2609 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2610 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2611 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2612 #else
2613 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2614 #endif
2615 #endif
2616 #ifdef SSL_OP_NO_TLSv1_2
2617 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2618 #endif
2619 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2620 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2621 #endif
2622 #ifdef SSL_OP_SINGLE_DH_USE
2623 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2624 #endif
2625 #ifdef SSL_OP_SINGLE_ECDH_USE
2626 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2627 #endif
2628 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2629 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2630 #endif
2631 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2632 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2633 #endif
2634 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2635 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2636 #endif
2637 #ifdef SSL_OP_TLS_D5_BUG
2638 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2639 #endif
2640 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2641 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2642 #endif
2643 };
2644 static int exim_openssl_options_size =
2645 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2646
2647
2648 static BOOL
2649 tls_openssl_one_option_parse(uschar *name, long *value)
2650 {
2651 int first = 0;
2652 int last = exim_openssl_options_size;
2653 while (last > first)
2654 {
2655 int middle = (first + last)/2;
2656 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2657 if (c == 0)
2658 {
2659 *value = exim_openssl_options[middle].value;
2660 return TRUE;
2661 }
2662 else if (c > 0)
2663 first = middle + 1;
2664 else
2665 last = middle;
2666 }
2667 return FALSE;
2668 }
2669
2670
2671
2672
2673 /*************************************************
2674 * OpenSSL option parsing logic *
2675 *************************************************/
2676
2677 /* OpenSSL has a number of compatibility options which an administrator might
2678 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2679 we look like log_selector.
2680
2681 Arguments:
2682 option_spec the administrator-supplied string of options
2683 results ptr to long storage for the options bitmap
2684 Returns success or failure
2685 */
2686
2687 BOOL
2688 tls_openssl_options_parse(uschar *option_spec, long *results)
2689 {
2690 long result, item;
2691 uschar *s, *end;
2692 uschar keep_c;
2693 BOOL adding, item_parsed;
2694
2695 result = 0L;
2696 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2697 * from default because it increases BEAST susceptibility. */
2698 #ifdef SSL_OP_NO_SSLv2
2699 result |= SSL_OP_NO_SSLv2;
2700 #endif
2701
2702 if (option_spec == NULL)
2703 {
2704 *results = result;
2705 return TRUE;
2706 }
2707
2708 for (s=option_spec; *s != '\0'; /**/)
2709 {
2710 while (isspace(*s)) ++s;
2711 if (*s == '\0')
2712 break;
2713 if (*s != '+' && *s != '-')
2714 {
2715 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2716 "+ or - expected but found \"%s\"\n", s);
2717 return FALSE;
2718 }
2719 adding = *s++ == '+';
2720 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2721 keep_c = *end;
2722 *end = '\0';
2723 item_parsed = tls_openssl_one_option_parse(s, &item);
2724 if (!item_parsed)
2725 {
2726 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2727 return FALSE;
2728 }
2729 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2730 adding ? "adding" : "removing", result, item, s);
2731 if (adding)
2732 result |= item;
2733 else
2734 result &= ~item;
2735 *end = keep_c;
2736 s = end;
2737 }
2738
2739 *results = result;
2740 return TRUE;
2741 }
2742
2743 /* vi: aw ai sw=2
2744 */
2745 /* End of tls-openssl.c */
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