98762fd624999ab482a72eb8592aa8ed320589e8
[exim.git] / src / src / tls-openssl.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
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 OPENSSL_NO_ECDH
26 # include <openssl/ec.h>
27 #endif
28 #ifndef DISABLE_OCSP
29 # include <openssl/ocsp.h>
30 #endif
31 #ifdef EXPERIMENTAL_DANE
32 # include <danessl.h>
33 #endif
34
35
36 #ifndef DISABLE_OCSP
37 # define EXIM_OCSP_SKEW_SECONDS (300L)
38 # define EXIM_OCSP_MAX_AGE (-1L)
39 #endif
40
41 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
42 # define EXIM_HAVE_OPENSSL_TLSEXT
43 #endif
44
45 /*
46 * X509_check_host provides sane certificate hostname checking, but was added
47 * to OpenSSL late, after other projects forked off the code-base. So in
48 * addition to guarding against the base version number, beware that LibreSSL
49 * does not (at this time) support this function.
50 *
51 * If LibreSSL gains a different API, perhaps via libtls, then we'll probably
52 * opt to disentangle and ask a LibreSSL user to provide glue for a third
53 * crypto provider for libtls instead of continuing to tie the OpenSSL glue
54 * into even twistier knots. If LibreSSL gains the same API, we can just
55 * change this guard and punt the issue for a while longer.
56 */
57 #ifndef LIBRESSL_VERSION_NUMBER
58 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
59 # define EXIM_HAVE_OPENSSL_CHECKHOST
60 # endif
61 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
62 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
63 # define EXIM_HAVE_OPENSSL_CHECKHOST
64 # endif
65
66 # if !defined(OPENSSL_NO_ECDH)
67 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
68 # define EXIM_HAVE_ECDH
69 # endif
70 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
71 # define EXIM_HAVE_OPENSSL_ECDH_AUTO
72 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
73 # endif
74 # endif
75 #endif
76
77 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
78 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
79 # define DISABLE_OCSP
80 #endif
81
82 /* Structure for collecting random data for seeding. */
83
84 typedef struct randstuff {
85 struct timeval tv;
86 pid_t p;
87 } randstuff;
88
89 /* Local static variables */
90
91 static BOOL client_verify_callback_called = FALSE;
92 static BOOL server_verify_callback_called = FALSE;
93 static const uschar *sid_ctx = US"exim";
94
95 /* We have three different contexts to care about.
96
97 Simple case: client, `client_ctx`
98 As a client, we can be doing a callout or cut-through delivery while receiving
99 a message. So we have a client context, which should have options initialised
100 from the SMTP Transport.
101
102 Server:
103 There are two cases: with and without ServerNameIndication from the client.
104 Given TLS SNI, we can be using different keys, certs and various other
105 configuration settings, because they're re-expanded with $tls_sni set. This
106 allows vhosting with TLS. This SNI is sent in the handshake.
107 A client might not send SNI, so we need a fallback, and an initial setup too.
108 So as a server, we start out using `server_ctx`.
109 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
110 `server_sni` from `server_ctx` and then initialise settings by re-expanding
111 configuration.
112 */
113
114 static SSL_CTX *client_ctx = NULL;
115 static SSL_CTX *server_ctx = NULL;
116 static SSL *client_ssl = NULL;
117 static SSL *server_ssl = NULL;
118
119 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
120 static SSL_CTX *server_sni = NULL;
121 #endif
122
123 static char ssl_errstring[256];
124
125 static int ssl_session_timeout = 200;
126 static BOOL client_verify_optional = FALSE;
127 static BOOL server_verify_optional = FALSE;
128
129 static BOOL reexpand_tls_files_for_sni = FALSE;
130
131
132 typedef struct tls_ext_ctx_cb {
133 uschar *certificate;
134 uschar *privatekey;
135 #ifndef DISABLE_OCSP
136 BOOL is_server;
137 union {
138 struct {
139 uschar *file;
140 uschar *file_expanded;
141 OCSP_RESPONSE *response;
142 } server;
143 struct {
144 X509_STORE *verify_store; /* non-null if status requested */
145 BOOL verify_required;
146 } client;
147 } u_ocsp;
148 #endif
149 uschar *dhparam;
150 /* these are cached from first expand */
151 uschar *server_cipher_list;
152 /* only passed down to tls_error: */
153 host_item *host;
154 const uschar * verify_cert_hostnames;
155 #ifndef DISABLE_EVENT
156 uschar * event_action;
157 #endif
158 } tls_ext_ctx_cb;
159
160 /* should figure out a cleanup of API to handle state preserved per
161 implementation, for various reasons, which can be void * in the APIs.
162 For now, we hack around it. */
163 tls_ext_ctx_cb *client_static_cbinfo = NULL;
164 tls_ext_ctx_cb *server_static_cbinfo = NULL;
165
166 static int
167 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
168 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
169
170 /* Callbacks */
171 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
172 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
173 #endif
174 #ifndef DISABLE_OCSP
175 static int tls_server_stapling_cb(SSL *s, void *arg);
176 #endif
177
178
179 /*************************************************
180 * Handle TLS error *
181 *************************************************/
182
183 /* Called from lots of places when errors occur before actually starting to do
184 the TLS handshake, that is, while the session is still in clear. Always returns
185 DEFER for a server and FAIL for a client so that most calls can use "return
186 tls_error(...)" to do this processing and then give an appropriate return. A
187 single function is used for both server and client, because it is called from
188 some shared functions.
189
190 Argument:
191 prefix text to include in the logged error
192 host NULL if setting up a server;
193 the connected host if setting up a client
194 msg error message or NULL if we should ask OpenSSL
195
196 Returns: OK/DEFER/FAIL
197 */
198
199 static int
200 tls_error(uschar * prefix, const host_item * host, uschar * msg)
201 {
202 if (!msg)
203 {
204 ERR_error_string(ERR_get_error(), ssl_errstring);
205 msg = (uschar *)ssl_errstring;
206 }
207
208 if (host)
209 {
210 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
211 host->name, host->address, prefix, msg);
212 return FAIL;
213 }
214 else
215 {
216 uschar *conn_info = smtp_get_connection_info();
217 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
218 conn_info += 5;
219 /* I'd like to get separated H= here, but too hard for now */
220 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
221 conn_info, prefix, msg);
222 return DEFER;
223 }
224 }
225
226
227
228 /*************************************************
229 * Callback to generate RSA key *
230 *************************************************/
231
232 /*
233 Arguments:
234 s SSL connection
235 export not used
236 keylength keylength
237
238 Returns: pointer to generated key
239 */
240
241 static RSA *
242 rsa_callback(SSL *s, int export, int keylength)
243 {
244 RSA *rsa_key;
245 export = export; /* Shut picky compilers up */
246 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
247 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
248 if (rsa_key == NULL)
249 {
250 ERR_error_string(ERR_get_error(), ssl_errstring);
251 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
252 ssl_errstring);
253 return NULL;
254 }
255 return rsa_key;
256 }
257
258
259
260 /* Extreme debug
261 #ifndef DISABLE_OCSP
262 void
263 x509_store_dump_cert_s_names(X509_STORE * store)
264 {
265 STACK_OF(X509_OBJECT) * roots= store->objs;
266 int i;
267 static uschar name[256];
268
269 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
270 {
271 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
272 if(tmp_obj->type == X509_LU_X509)
273 {
274 X509 * current_cert= tmp_obj->data.x509;
275 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
276 name[sizeof(name)-1] = '\0';
277 debug_printf(" %s\n", name);
278 }
279 }
280 }
281 #endif
282 */
283
284
285 #ifndef DISABLE_EVENT
286 static int
287 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
288 BOOL *calledp, const BOOL *optionalp, const uschar * what)
289 {
290 uschar * ev;
291 uschar * yield;
292 X509 * old_cert;
293
294 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
295 if (ev)
296 {
297 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
298 old_cert = tlsp->peercert;
299 tlsp->peercert = X509_dup(cert);
300 /* NB we do not bother setting peerdn */
301 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
302 {
303 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
304 "depth=%d cert=%s: %s",
305 tlsp == &tls_out ? deliver_host_address : sender_host_address,
306 what, depth, dn, yield);
307 *calledp = TRUE;
308 if (!*optionalp)
309 {
310 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
311 return 1; /* reject (leaving peercert set) */
312 }
313 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
314 "(host in tls_try_verify_hosts)\n");
315 }
316 X509_free(tlsp->peercert);
317 tlsp->peercert = old_cert;
318 }
319 return 0;
320 }
321 #endif
322
323 /*************************************************
324 * Callback for verification *
325 *************************************************/
326
327 /* The SSL library does certificate verification if set up to do so. This
328 callback has the current yes/no state is in "state". If verification succeeded,
329 we set the certificate-verified flag. If verification failed, what happens
330 depends on whether the client is required to present a verifiable certificate
331 or not.
332
333 If verification is optional, we change the state to yes, but still log the
334 verification error. For some reason (it really would help to have proper
335 documentation of OpenSSL), this callback function then gets called again, this
336 time with state = 1. We must take care not to set the private verified flag on
337 the second time through.
338
339 Note: this function is not called if the client fails to present a certificate
340 when asked. We get here only if a certificate has been received. Handling of
341 optional verification for this case is done when requesting SSL to verify, by
342 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
343
344 May be called multiple times for different issues with a certificate, even
345 for a given "depth" in the certificate chain.
346
347 Arguments:
348 preverify_ok current yes/no state as 1/0
349 x509ctx certificate information.
350 tlsp per-direction (client vs. server) support data
351 calledp has-been-called flag
352 optionalp verification-is-optional flag
353
354 Returns: 0 if verification should fail, otherwise 1
355 */
356
357 static int
358 verify_callback(int preverify_ok, X509_STORE_CTX *x509ctx,
359 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
360 {
361 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
362 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
363 uschar dn[256];
364
365 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
366 dn[sizeof(dn)-1] = '\0';
367
368 if (preverify_ok == 0)
369 {
370 log_write(0, LOG_MAIN, "[%s] SSL verify error: depth=%d error=%s cert=%s",
371 tlsp == &tls_out ? deliver_host_address : sender_host_address,
372 depth,
373 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
374 dn);
375 *calledp = TRUE;
376 if (!*optionalp)
377 {
378 if (!tlsp->peercert)
379 tlsp->peercert = X509_dup(cert); /* record failing cert */
380 return 0; /* reject */
381 }
382 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
383 "tls_try_verify_hosts)\n");
384 }
385
386 else if (depth != 0)
387 {
388 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
389 #ifndef DISABLE_OCSP
390 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
391 { /* client, wanting stapling */
392 /* Add the server cert's signing chain as the one
393 for the verification of the OCSP stapled information. */
394
395 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
396 cert))
397 ERR_clear_error();
398 }
399 #endif
400 #ifndef DISABLE_EVENT
401 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
402 return 0; /* reject, with peercert set */
403 #endif
404 }
405 else
406 {
407 const uschar * verify_cert_hostnames;
408
409 if ( tlsp == &tls_out
410 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
411 /* client, wanting hostname check */
412 {
413
414 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
415 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
416 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
417 # endif
418 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
419 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
420 # endif
421 int sep = 0;
422 const uschar * list = verify_cert_hostnames;
423 uschar * name;
424 int rc;
425 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
426 if ((rc = X509_check_host(cert, CCS name, 0,
427 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
428 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
429 NULL)))
430 {
431 if (rc < 0)
432 {
433 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
434 tlsp == &tls_out ? deliver_host_address : sender_host_address);
435 name = NULL;
436 }
437 break;
438 }
439 if (!name)
440 #else
441 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
442 #endif
443 {
444 log_write(0, LOG_MAIN,
445 "[%s] SSL verify error: certificate name mismatch: \"%s\"",
446 tlsp == &tls_out ? deliver_host_address : sender_host_address,
447 dn);
448 *calledp = TRUE;
449 if (!*optionalp)
450 {
451 if (!tlsp->peercert)
452 tlsp->peercert = X509_dup(cert); /* record failing cert */
453 return 0; /* reject */
454 }
455 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
456 "tls_try_verify_hosts)\n");
457 }
458 }
459
460 #ifndef DISABLE_EVENT
461 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
462 return 0; /* reject, with peercert set */
463 #endif
464
465 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
466 *calledp ? "" : " authenticated", dn);
467 if (!*calledp) tlsp->certificate_verified = TRUE;
468 *calledp = TRUE;
469 }
470
471 return 1; /* accept, at least for this level */
472 }
473
474 static int
475 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
476 {
477 return verify_callback(preverify_ok, x509ctx, &tls_out,
478 &client_verify_callback_called, &client_verify_optional);
479 }
480
481 static int
482 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
483 {
484 return verify_callback(preverify_ok, x509ctx, &tls_in,
485 &server_verify_callback_called, &server_verify_optional);
486 }
487
488
489 #ifdef EXPERIMENTAL_DANE
490
491 /* This gets called *by* the dane library verify callback, which interposes
492 itself.
493 */
494 static int
495 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
496 {
497 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
498 uschar dn[256];
499 #ifndef DISABLE_EVENT
500 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
501 BOOL dummy_called, optional = FALSE;
502 #endif
503
504 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
505 dn[sizeof(dn)-1] = '\0';
506
507 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
508 preverify_ok ? "ok":"BAD", depth, dn);
509
510 #ifndef DISABLE_EVENT
511 if (verify_event(&tls_out, cert, depth, dn,
512 &dummy_called, &optional, US"DANE"))
513 return 0; /* reject, with peercert set */
514 #endif
515
516 if (preverify_ok == 1)
517 tls_out.dane_verified =
518 tls_out.certificate_verified = TRUE;
519 else
520 {
521 int err = X509_STORE_CTX_get_error(x509ctx);
522 DEBUG(D_tls)
523 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
524 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
525 preverify_ok = 1;
526 }
527 return preverify_ok;
528 }
529
530 #endif /*EXPERIMENTAL_DANE*/
531
532
533 /*************************************************
534 * Information callback *
535 *************************************************/
536
537 /* The SSL library functions call this from time to time to indicate what they
538 are doing. We copy the string to the debugging output when TLS debugging has
539 been requested.
540
541 Arguments:
542 s the SSL connection
543 where
544 ret
545
546 Returns: nothing
547 */
548
549 static void
550 info_callback(SSL *s, int where, int ret)
551 {
552 where = where;
553 ret = ret;
554 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
555 }
556
557
558
559 /*************************************************
560 * Initialize for DH *
561 *************************************************/
562
563 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
564
565 Arguments:
566 sctx The current SSL CTX (inbound or outbound)
567 dhparam DH parameter file or fixed parameter identity string
568 host connected host, if client; NULL if server
569
570 Returns: TRUE if OK (nothing to set up, or setup worked)
571 */
572
573 static BOOL
574 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host)
575 {
576 BIO *bio;
577 DH *dh;
578 uschar *dhexpanded;
579 const char *pem;
580
581 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
582 return FALSE;
583
584 if (!dhexpanded || !*dhexpanded)
585 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
586 else if (dhexpanded[0] == '/')
587 {
588 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
589 {
590 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
591 host, US strerror(errno));
592 return FALSE;
593 }
594 }
595 else
596 {
597 if (Ustrcmp(dhexpanded, "none") == 0)
598 {
599 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
600 return TRUE;
601 }
602
603 if (!(pem = std_dh_prime_named(dhexpanded)))
604 {
605 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
606 host, US strerror(errno));
607 return FALSE;
608 }
609 bio = BIO_new_mem_buf(CS pem, -1);
610 }
611
612 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
613 {
614 BIO_free(bio);
615 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
616 host, NULL);
617 return FALSE;
618 }
619
620 /* Even if it is larger, we silently return success rather than cause things
621 * to fail out, so that a too-large DH will not knock out all TLS; it's a
622 * debatable choice. */
623 if ((8*DH_size(dh)) > tls_dh_max_bits)
624 {
625 DEBUG(D_tls)
626 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
627 8*DH_size(dh), tls_dh_max_bits);
628 }
629 else
630 {
631 SSL_CTX_set_tmp_dh(sctx, dh);
632 DEBUG(D_tls)
633 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
634 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
635 }
636
637 DH_free(dh);
638 BIO_free(bio);
639
640 return TRUE;
641 }
642
643
644
645
646 /*************************************************
647 * Initialize for ECDH *
648 *************************************************/
649
650 /* Load parameters for ECDH encryption.
651
652 For now, we stick to NIST P-256 because: it's simple and easy to configure;
653 it avoids any patent issues that might bite redistributors; despite events in
654 the news and concerns over curve choices, we're not cryptographers, we're not
655 pretending to be, and this is "good enough" to be better than no support,
656 protecting against most adversaries. Given another year or two, there might
657 be sufficient clarity about a "right" way forward to let us make an informed
658 decision, instead of a knee-jerk reaction.
659
660 Longer-term, we should look at supporting both various named curves and
661 external files generated with "openssl ecparam", much as we do for init_dh().
662 We should also support "none" as a value, to explicitly avoid initialisation.
663
664 Patches welcome.
665
666 Arguments:
667 sctx The current SSL CTX (inbound or outbound)
668 host connected host, if client; NULL if server
669
670 Returns: TRUE if OK (nothing to set up, or setup worked)
671 */
672
673 static BOOL
674 init_ecdh(SSL_CTX * sctx, host_item * host)
675 {
676 #ifdef OPENSSL_NO_ECDH
677 return TRUE;
678 #else
679
680 EC_KEY * ecdh;
681 uschar * exp_curve;
682 int nid;
683 BOOL rv;
684
685 if (host) /* No ECDH setup for clients, only for servers */
686 return TRUE;
687
688 # ifndef EXIM_HAVE_ECDH
689 DEBUG(D_tls)
690 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
691 return TRUE;
692 # else
693
694 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve))
695 return FALSE;
696 if (!exp_curve || !*exp_curve)
697 return TRUE;
698
699 # ifdef EXIM_HAVE_OPENSSL_ECDH_AUTO
700 /* check if new enough library to support auto ECDH temp key parameter selection */
701 if (Ustrcmp(exp_curve, "auto") == 0)
702 {
703 DEBUG(D_tls) debug_printf(
704 "ECDH temp key parameter settings: OpenSSL 1.2+ autoselection\n");
705 SSL_CTX_set_ecdh_auto(sctx, 1);
706 return TRUE;
707 }
708 # endif
709
710 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
711 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
712 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
713 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
714 # endif
715 )
716 {
717 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'",
718 exp_curve),
719 host, NULL);
720 return FALSE;
721 }
722
723 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
724 {
725 tls_error(US"Unable to create ec curve", host, NULL);
726 return FALSE;
727 }
728
729 /* The "tmp" in the name here refers to setting a temporary key
730 not to the stability of the interface. */
731
732 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
733 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL);
734 else
735 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
736
737 EC_KEY_free(ecdh);
738 return !rv;
739
740 # endif /*EXIM_HAVE_ECDH*/
741 #endif /*OPENSSL_NO_ECDH*/
742 }
743
744
745
746
747 #ifndef DISABLE_OCSP
748 /*************************************************
749 * Load OCSP information into state *
750 *************************************************/
751
752 /* Called to load the server OCSP response from the given file into memory, once
753 caller has determined this is needed. Checks validity. Debugs a message
754 if invalid.
755
756 ASSUMES: single response, for single cert.
757
758 Arguments:
759 sctx the SSL_CTX* to update
760 cbinfo various parts of session state
761 expanded the filename putatively holding an OCSP response
762
763 */
764
765 static void
766 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
767 {
768 BIO *bio;
769 OCSP_RESPONSE *resp;
770 OCSP_BASICRESP *basic_response;
771 OCSP_SINGLERESP *single_response;
772 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
773 X509_STORE *store;
774 unsigned long verify_flags;
775 int status, reason, i;
776
777 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
778 if (cbinfo->u_ocsp.server.response)
779 {
780 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
781 cbinfo->u_ocsp.server.response = NULL;
782 }
783
784 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
785 if (!bio)
786 {
787 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
788 cbinfo->u_ocsp.server.file_expanded);
789 return;
790 }
791
792 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
793 BIO_free(bio);
794 if (!resp)
795 {
796 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
797 return;
798 }
799
800 status = OCSP_response_status(resp);
801 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
802 {
803 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
804 OCSP_response_status_str(status), status);
805 goto bad;
806 }
807
808 basic_response = OCSP_response_get1_basic(resp);
809 if (!basic_response)
810 {
811 DEBUG(D_tls)
812 debug_printf("OCSP response parse error: unable to extract basic response.\n");
813 goto bad;
814 }
815
816 store = SSL_CTX_get_cert_store(sctx);
817 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
818
819 /* May need to expose ability to adjust those flags?
820 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
821 OCSP_TRUSTOTHER OCSP_NOINTERN */
822
823 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
824 if (i <= 0)
825 {
826 DEBUG(D_tls) {
827 ERR_error_string(ERR_get_error(), ssl_errstring);
828 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
829 }
830 goto bad;
831 }
832
833 /* Here's the simplifying assumption: there's only one response, for the
834 one certificate we use, and nothing for anything else in a chain. If this
835 proves false, we need to extract a cert id from our issued cert
836 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
837 right cert in the stack and then calls OCSP_single_get0_status()).
838
839 I'm hoping to avoid reworking a bunch more of how we handle state here. */
840 single_response = OCSP_resp_get0(basic_response, 0);
841 if (!single_response)
842 {
843 DEBUG(D_tls)
844 debug_printf("Unable to get first response from OCSP basic response.\n");
845 goto bad;
846 }
847
848 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
849 if (status != V_OCSP_CERTSTATUS_GOOD)
850 {
851 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
852 OCSP_cert_status_str(status), status,
853 OCSP_crl_reason_str(reason), reason);
854 goto bad;
855 }
856
857 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
858 {
859 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
860 goto bad;
861 }
862
863 supply_response:
864 cbinfo->u_ocsp.server.response = resp;
865 return;
866
867 bad:
868 if (running_in_test_harness)
869 {
870 extern char ** environ;
871 uschar ** p;
872 for (p = USS environ; *p != NULL; p++)
873 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
874 {
875 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
876 goto supply_response;
877 }
878 }
879 return;
880 }
881 #endif /*!DISABLE_OCSP*/
882
883
884
885
886 /*************************************************
887 * Expand key and cert file specs *
888 *************************************************/
889
890 /* Called once during tls_init and possibly again during TLS setup, for a
891 new context, if Server Name Indication was used and tls_sni was seen in
892 the certificate string.
893
894 Arguments:
895 sctx the SSL_CTX* to update
896 cbinfo various parts of session state
897
898 Returns: OK/DEFER/FAIL
899 */
900
901 static int
902 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
903 {
904 uschar *expanded;
905
906 if (cbinfo->certificate == NULL)
907 return OK;
908
909 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
910 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
911 Ustrstr(cbinfo->certificate, US"tls_out_sni")
912 )
913 reexpand_tls_files_for_sni = TRUE;
914
915 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
916 return DEFER;
917
918 if (expanded != NULL)
919 {
920 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
921 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
922 return tls_error(string_sprintf(
923 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
924 cbinfo->host, NULL);
925 }
926
927 if (cbinfo->privatekey != NULL &&
928 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
929 return DEFER;
930
931 /* If expansion was forced to fail, key_expanded will be NULL. If the result
932 of the expansion is an empty string, ignore it also, and assume the private
933 key is in the same file as the certificate. */
934
935 if (expanded && *expanded)
936 {
937 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
938 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
939 return tls_error(string_sprintf(
940 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
941 }
942
943 #ifndef DISABLE_OCSP
944 if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
945 {
946 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
947 return DEFER;
948
949 if (expanded && *expanded)
950 {
951 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
952 if ( cbinfo->u_ocsp.server.file_expanded
953 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
954 {
955 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
956 }
957 else
958 {
959 ocsp_load_response(sctx, cbinfo, expanded);
960 }
961 }
962 }
963 #endif
964
965 return OK;
966 }
967
968
969
970
971 /*************************************************
972 * Callback to handle SNI *
973 *************************************************/
974
975 /* Called when acting as server during the TLS session setup if a Server Name
976 Indication extension was sent by the client.
977
978 API documentation is OpenSSL s_server.c implementation.
979
980 Arguments:
981 s SSL* of the current session
982 ad unknown (part of OpenSSL API) (unused)
983 arg Callback of "our" registered data
984
985 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
986 */
987
988 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
989 static int
990 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
991 {
992 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
993 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
994 int rc;
995 int old_pool = store_pool;
996
997 if (!servername)
998 return SSL_TLSEXT_ERR_OK;
999
1000 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1001 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1002
1003 /* Make the extension value available for expansion */
1004 store_pool = POOL_PERM;
1005 tls_in.sni = string_copy(US servername);
1006 store_pool = old_pool;
1007
1008 if (!reexpand_tls_files_for_sni)
1009 return SSL_TLSEXT_ERR_OK;
1010
1011 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1012 not confident that memcpy wouldn't break some internal reference counting.
1013 Especially since there's a references struct member, which would be off. */
1014
1015 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1016 {
1017 ERR_error_string(ERR_get_error(), ssl_errstring);
1018 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1019 return SSL_TLSEXT_ERR_NOACK;
1020 }
1021
1022 /* Not sure how many of these are actually needed, since SSL object
1023 already exists. Might even need this selfsame callback, for reneg? */
1024
1025 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1026 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1027 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1028 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1029 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1030 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1031
1032 if ( !init_dh(server_sni, cbinfo->dhparam, NULL)
1033 || !init_ecdh(server_sni, NULL)
1034 )
1035 return SSL_TLSEXT_ERR_NOACK;
1036
1037 if (cbinfo->server_cipher_list)
1038 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
1039 #ifndef DISABLE_OCSP
1040 if (cbinfo->u_ocsp.server.file)
1041 {
1042 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1043 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1044 }
1045 #endif
1046
1047 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
1048 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
1049
1050 /* do this after setup_certs, because this can require the certs for verifying
1051 OCSP information. */
1052 if ((rc = tls_expand_session_files(server_sni, cbinfo)) != OK)
1053 return SSL_TLSEXT_ERR_NOACK;
1054
1055 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1056 SSL_set_SSL_CTX(s, server_sni);
1057
1058 return SSL_TLSEXT_ERR_OK;
1059 }
1060 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1061
1062
1063
1064
1065 #ifndef DISABLE_OCSP
1066
1067 /*************************************************
1068 * Callback to handle OCSP Stapling *
1069 *************************************************/
1070
1071 /* Called when acting as server during the TLS session setup if the client
1072 requests OCSP information with a Certificate Status Request.
1073
1074 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1075 project.
1076
1077 */
1078
1079 static int
1080 tls_server_stapling_cb(SSL *s, void *arg)
1081 {
1082 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1083 uschar *response_der;
1084 int response_der_len;
1085
1086 DEBUG(D_tls)
1087 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1088 cbinfo->u_ocsp.server.response ? "have" : "lack");
1089
1090 tls_in.ocsp = OCSP_NOT_RESP;
1091 if (!cbinfo->u_ocsp.server.response)
1092 return SSL_TLSEXT_ERR_NOACK;
1093
1094 response_der = NULL;
1095 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
1096 &response_der);
1097 if (response_der_len <= 0)
1098 return SSL_TLSEXT_ERR_NOACK;
1099
1100 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1101 tls_in.ocsp = OCSP_VFIED;
1102 return SSL_TLSEXT_ERR_OK;
1103 }
1104
1105
1106 static void
1107 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1108 {
1109 BIO_printf(bp, "\t%s: ", str);
1110 ASN1_GENERALIZEDTIME_print(bp, time);
1111 BIO_puts(bp, "\n");
1112 }
1113
1114 static int
1115 tls_client_stapling_cb(SSL *s, void *arg)
1116 {
1117 tls_ext_ctx_cb * cbinfo = arg;
1118 const unsigned char * p;
1119 int len;
1120 OCSP_RESPONSE * rsp;
1121 OCSP_BASICRESP * bs;
1122 int i;
1123
1124 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1125 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1126 if(!p)
1127 {
1128 /* Expect this when we requested ocsp but got none */
1129 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1130 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1131 else
1132 DEBUG(D_tls) debug_printf(" null\n");
1133 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1134 }
1135
1136 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1137 {
1138 tls_out.ocsp = OCSP_FAILED;
1139 if (LOGGING(tls_cipher))
1140 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1141 else
1142 DEBUG(D_tls) debug_printf(" parse error\n");
1143 return 0;
1144 }
1145
1146 if(!(bs = OCSP_response_get1_basic(rsp)))
1147 {
1148 tls_out.ocsp = OCSP_FAILED;
1149 if (LOGGING(tls_cipher))
1150 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1151 else
1152 DEBUG(D_tls) debug_printf(" error parsing response\n");
1153 OCSP_RESPONSE_free(rsp);
1154 return 0;
1155 }
1156
1157 /* We'd check the nonce here if we'd put one in the request. */
1158 /* However that would defeat cacheability on the server so we don't. */
1159
1160 /* This section of code reworked from OpenSSL apps source;
1161 The OpenSSL Project retains copyright:
1162 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1163 */
1164 {
1165 BIO * bp = NULL;
1166 int status, reason;
1167 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1168
1169 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1170
1171 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1172
1173 /* Use the chain that verified the server cert to verify the stapled info */
1174 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1175
1176 if ((i = OCSP_basic_verify(bs, NULL,
1177 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1178 {
1179 tls_out.ocsp = OCSP_FAILED;
1180 if (LOGGING(tls_cipher))
1181 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1182 BIO_printf(bp, "OCSP response verify failure\n");
1183 ERR_print_errors(bp);
1184 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1185 goto out;
1186 }
1187
1188 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1189
1190 {
1191 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1192 OCSP_SINGLERESP * single;
1193
1194 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1195 {
1196 tls_out.ocsp = OCSP_FAILED;
1197 log_write(0, LOG_MAIN, "OCSP stapling "
1198 "with multiple responses not handled");
1199 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1200 goto out;
1201 }
1202 single = OCSP_resp_get0(bs, 0);
1203 status = OCSP_single_get0_status(single, &reason, &rev,
1204 &thisupd, &nextupd);
1205 }
1206
1207 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1208 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1209 if (!OCSP_check_validity(thisupd, nextupd,
1210 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1211 {
1212 tls_out.ocsp = OCSP_FAILED;
1213 DEBUG(D_tls) ERR_print_errors(bp);
1214 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1215 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1216 }
1217 else
1218 {
1219 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1220 OCSP_cert_status_str(status));
1221 switch(status)
1222 {
1223 case V_OCSP_CERTSTATUS_GOOD:
1224 tls_out.ocsp = OCSP_VFIED;
1225 i = 1;
1226 break;
1227 case V_OCSP_CERTSTATUS_REVOKED:
1228 tls_out.ocsp = OCSP_FAILED;
1229 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1230 reason != -1 ? "; reason: " : "",
1231 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1232 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1233 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1234 break;
1235 default:
1236 tls_out.ocsp = OCSP_FAILED;
1237 log_write(0, LOG_MAIN,
1238 "Server certificate status unknown, in OCSP stapling");
1239 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1240 break;
1241 }
1242 }
1243 out:
1244 BIO_free(bp);
1245 }
1246
1247 OCSP_RESPONSE_free(rsp);
1248 return i;
1249 }
1250 #endif /*!DISABLE_OCSP*/
1251
1252
1253 /*************************************************
1254 * Initialize for TLS *
1255 *************************************************/
1256
1257 /* Called from both server and client code, to do preliminary initialization
1258 of the library. We allocate and return a context structure.
1259
1260 Arguments:
1261 ctxp returned SSL context
1262 host connected host, if client; NULL if server
1263 dhparam DH parameter file
1264 certificate certificate file
1265 privatekey private key
1266 ocsp_file file of stapling info (server); flag for require ocsp (client)
1267 addr address if client; NULL if server (for some randomness)
1268 cbp place to put allocated callback context
1269
1270 Returns: OK/DEFER/FAIL
1271 */
1272
1273 static int
1274 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1275 uschar *privatekey,
1276 #ifndef DISABLE_OCSP
1277 uschar *ocsp_file,
1278 #endif
1279 address_item *addr, tls_ext_ctx_cb ** cbp)
1280 {
1281 long init_options;
1282 int rc;
1283 BOOL okay;
1284 tls_ext_ctx_cb * cbinfo;
1285
1286 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1287 cbinfo->certificate = certificate;
1288 cbinfo->privatekey = privatekey;
1289 #ifndef DISABLE_OCSP
1290 if ((cbinfo->is_server = host==NULL))
1291 {
1292 cbinfo->u_ocsp.server.file = ocsp_file;
1293 cbinfo->u_ocsp.server.file_expanded = NULL;
1294 cbinfo->u_ocsp.server.response = NULL;
1295 }
1296 else
1297 cbinfo->u_ocsp.client.verify_store = NULL;
1298 #endif
1299 cbinfo->dhparam = dhparam;
1300 cbinfo->server_cipher_list = NULL;
1301 cbinfo->host = host;
1302 #ifndef DISABLE_EVENT
1303 cbinfo->event_action = NULL;
1304 #endif
1305
1306 SSL_load_error_strings(); /* basic set up */
1307 OpenSSL_add_ssl_algorithms();
1308
1309 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1310 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1311 list of available digests. */
1312 EVP_add_digest(EVP_sha256());
1313 #endif
1314
1315 /* Create a context.
1316 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1317 negotiation in the different methods; as far as I can tell, the only
1318 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1319 when OpenSSL is built without SSLv2 support.
1320 By disabling with openssl_options, we can let admins re-enable with the
1321 existing knob. */
1322
1323 *ctxp = SSL_CTX_new((host == NULL)?
1324 SSLv23_server_method() : SSLv23_client_method());
1325
1326 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1327
1328 /* It turns out that we need to seed the random number generator this early in
1329 order to get the full complement of ciphers to work. It took me roughly a day
1330 of work to discover this by experiment.
1331
1332 On systems that have /dev/urandom, SSL may automatically seed itself from
1333 there. Otherwise, we have to make something up as best we can. Double check
1334 afterwards. */
1335
1336 if (!RAND_status())
1337 {
1338 randstuff r;
1339 gettimeofday(&r.tv, NULL);
1340 r.p = getpid();
1341
1342 RAND_seed((uschar *)(&r), sizeof(r));
1343 RAND_seed((uschar *)big_buffer, big_buffer_size);
1344 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1345
1346 if (!RAND_status())
1347 return tls_error(US"RAND_status", host,
1348 US"unable to seed random number generator");
1349 }
1350
1351 /* Set up the information callback, which outputs if debugging is at a suitable
1352 level. */
1353
1354 DEBUG(D_tls) SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1355
1356 /* Automatically re-try reads/writes after renegotiation. */
1357 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1358
1359 /* Apply administrator-supplied work-arounds.
1360 Historically we applied just one requested option,
1361 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1362 moved to an administrator-controlled list of options to specify and
1363 grandfathered in the first one as the default value for "openssl_options".
1364
1365 No OpenSSL version number checks: the options we accept depend upon the
1366 availability of the option value macros from OpenSSL. */
1367
1368 okay = tls_openssl_options_parse(openssl_options, &init_options);
1369 if (!okay)
1370 return tls_error(US"openssl_options parsing failed", host, NULL);
1371
1372 if (init_options)
1373 {
1374 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1375 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1376 return tls_error(string_sprintf(
1377 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1378 }
1379 else
1380 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1381
1382 /* Initialize with DH parameters if supplied */
1383 /* Initialize ECDH temp key parameter selection */
1384
1385 if ( !init_dh(*ctxp, dhparam, host)
1386 || !init_ecdh(*ctxp, host)
1387 )
1388 return DEFER;
1389
1390 /* Set up certificate and key (and perhaps OCSP info) */
1391
1392 rc = tls_expand_session_files(*ctxp, cbinfo);
1393 if (rc != OK) return rc;
1394
1395 /* If we need to handle SNI, do so */
1396 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1397 if (host == NULL) /* server */
1398 {
1399 # ifndef DISABLE_OCSP
1400 /* We check u_ocsp.server.file, not server.response, because we care about if
1401 the option exists, not what the current expansion might be, as SNI might
1402 change the certificate and OCSP file in use between now and the time the
1403 callback is invoked. */
1404 if (cbinfo->u_ocsp.server.file)
1405 {
1406 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1407 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1408 }
1409 # endif
1410 /* We always do this, so that $tls_sni is available even if not used in
1411 tls_certificate */
1412 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1413 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1414 }
1415 # ifndef DISABLE_OCSP
1416 else /* client */
1417 if(ocsp_file) /* wanting stapling */
1418 {
1419 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1420 {
1421 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1422 return FAIL;
1423 }
1424 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1425 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1426 }
1427 # endif
1428 #endif
1429
1430 cbinfo->verify_cert_hostnames = NULL;
1431
1432 /* Set up the RSA callback */
1433
1434 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1435
1436 /* Finally, set the timeout, and we are done */
1437
1438 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1439 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1440
1441 *cbp = cbinfo;
1442
1443 return OK;
1444 }
1445
1446
1447
1448
1449 /*************************************************
1450 * Get name of cipher in use *
1451 *************************************************/
1452
1453 /*
1454 Argument: pointer to an SSL structure for the connection
1455 buffer to use for answer
1456 size of buffer
1457 pointer to number of bits for cipher
1458 Returns: nothing
1459 */
1460
1461 static void
1462 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1463 {
1464 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1465 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1466 the accessor functions use const in the prototype. */
1467 const SSL_CIPHER *c;
1468 const uschar *ver;
1469
1470 ver = (const uschar *)SSL_get_version(ssl);
1471
1472 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1473 SSL_CIPHER_get_bits(c, bits);
1474
1475 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1476 SSL_CIPHER_get_name(c), *bits);
1477
1478 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1479 }
1480
1481
1482 static void
1483 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1484 {
1485 /*XXX we might consider a list-of-certs variable for the cert chain.
1486 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1487 in list-handling functions, also consider the difference between the entire
1488 chain and the elements sent by the peer. */
1489
1490 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1491 if (!tlsp->peercert)
1492 tlsp->peercert = SSL_get_peer_certificate(ssl);
1493 /* Beware anonymous ciphers which lead to server_cert being NULL */
1494 if (tlsp->peercert)
1495 {
1496 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1497 peerdn[bsize-1] = '\0';
1498 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1499 }
1500 else
1501 tlsp->peerdn = NULL;
1502 }
1503
1504
1505
1506
1507
1508 /*************************************************
1509 * Set up for verifying certificates *
1510 *************************************************/
1511
1512 /* Called by both client and server startup
1513
1514 Arguments:
1515 sctx SSL_CTX* to initialise
1516 certs certs file or NULL
1517 crl CRL file or NULL
1518 host NULL in a server; the remote host in a client
1519 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1520 otherwise passed as FALSE
1521 cert_vfy_cb Callback function for certificate verification
1522
1523 Returns: OK/DEFER/FAIL
1524 */
1525
1526 static int
1527 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1528 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1529 {
1530 uschar *expcerts, *expcrl;
1531
1532 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1533 return DEFER;
1534
1535 if (expcerts && *expcerts)
1536 {
1537 /* Tell the library to use its compiled-in location for the system default
1538 CA bundle. Then add the ones specified in the config, if any. */
1539
1540 if (!SSL_CTX_set_default_verify_paths(sctx))
1541 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1542
1543 if (Ustrcmp(expcerts, "system") != 0)
1544 {
1545 struct stat statbuf;
1546
1547 if (Ustat(expcerts, &statbuf) < 0)
1548 {
1549 log_write(0, LOG_MAIN|LOG_PANIC,
1550 "failed to stat %s for certificates", expcerts);
1551 return DEFER;
1552 }
1553 else
1554 {
1555 uschar *file, *dir;
1556 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1557 { file = NULL; dir = expcerts; }
1558 else
1559 { file = expcerts; dir = NULL; }
1560
1561 /* If a certificate file is empty, the next function fails with an
1562 unhelpful error message. If we skip it, we get the correct behaviour (no
1563 certificates are recognized, but the error message is still misleading (it
1564 says no certificate was supplied.) But this is better. */
1565
1566 if ( (!file || statbuf.st_size > 0)
1567 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1568 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1569
1570 /* Load the list of CAs for which we will accept certs, for sending
1571 to the client. This is only for the one-file tls_verify_certificates
1572 variant.
1573 If a list isn't loaded into the server, but
1574 some verify locations are set, the server end appears to make
1575 a wildcard reqest for client certs.
1576 Meanwhile, the client library as default behaviour *ignores* the list
1577 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1578 Because of this, and that the dir variant is likely only used for
1579 the public-CA bundle (not for a private CA), not worth fixing.
1580 */
1581 if (file)
1582 {
1583 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1584
1585 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1586 sk_X509_NAME_num(names));
1587 SSL_CTX_set_client_CA_list(sctx, names);
1588 }
1589 }
1590 }
1591
1592 /* Handle a certificate revocation list. */
1593
1594 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1595
1596 /* This bit of code is now the version supplied by Lars Mainka. (I have
1597 merely reformatted it into the Exim code style.)
1598
1599 "From here I changed the code to add support for multiple crl's
1600 in pem format in one file or to support hashed directory entries in
1601 pem format instead of a file. This method now uses the library function
1602 X509_STORE_load_locations to add the CRL location to the SSL context.
1603 OpenSSL will then handle the verify against CA certs and CRLs by
1604 itself in the verify callback." */
1605
1606 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1607 if (expcrl && *expcrl)
1608 {
1609 struct stat statbufcrl;
1610 if (Ustat(expcrl, &statbufcrl) < 0)
1611 {
1612 log_write(0, LOG_MAIN|LOG_PANIC,
1613 "failed to stat %s for certificates revocation lists", expcrl);
1614 return DEFER;
1615 }
1616 else
1617 {
1618 /* is it a file or directory? */
1619 uschar *file, *dir;
1620 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1621 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1622 {
1623 file = NULL;
1624 dir = expcrl;
1625 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1626 }
1627 else
1628 {
1629 file = expcrl;
1630 dir = NULL;
1631 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1632 }
1633 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1634 return tls_error(US"X509_STORE_load_locations", host, NULL);
1635
1636 /* setting the flags to check against the complete crl chain */
1637
1638 X509_STORE_set_flags(cvstore,
1639 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1640 }
1641 }
1642
1643 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1644
1645 /* If verification is optional, don't fail if no certificate */
1646
1647 SSL_CTX_set_verify(sctx,
1648 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1649 cert_vfy_cb);
1650 }
1651
1652 return OK;
1653 }
1654
1655
1656
1657 /*************************************************
1658 * Start a TLS session in a server *
1659 *************************************************/
1660
1661 /* This is called when Exim is running as a server, after having received
1662 the STARTTLS command. It must respond to that command, and then negotiate
1663 a TLS session.
1664
1665 Arguments:
1666 require_ciphers allowed ciphers
1667
1668 Returns: OK on success
1669 DEFER for errors before the start of the negotiation
1670 FAIL for errors during the negotation; the server can't
1671 continue running.
1672 */
1673
1674 int
1675 tls_server_start(const uschar *require_ciphers)
1676 {
1677 int rc;
1678 uschar *expciphers;
1679 tls_ext_ctx_cb *cbinfo;
1680 static uschar peerdn[256];
1681 static uschar cipherbuf[256];
1682
1683 /* Check for previous activation */
1684
1685 if (tls_in.active >= 0)
1686 {
1687 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1688 smtp_printf("554 Already in TLS\r\n");
1689 return FAIL;
1690 }
1691
1692 /* Initialize the SSL library. If it fails, it will already have logged
1693 the error. */
1694
1695 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1696 #ifndef DISABLE_OCSP
1697 tls_ocsp_file,
1698 #endif
1699 NULL, &server_static_cbinfo);
1700 if (rc != OK) return rc;
1701 cbinfo = server_static_cbinfo;
1702
1703 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1704 return FAIL;
1705
1706 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1707 were historically separated by underscores. So that I can use either form in my
1708 tests, and also for general convenience, we turn underscores into hyphens here.
1709 */
1710
1711 if (expciphers != NULL)
1712 {
1713 uschar *s = expciphers;
1714 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1715 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1716 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1717 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1718 cbinfo->server_cipher_list = expciphers;
1719 }
1720
1721 /* If this is a host for which certificate verification is mandatory or
1722 optional, set up appropriately. */
1723
1724 tls_in.certificate_verified = FALSE;
1725 #ifdef EXPERIMENTAL_DANE
1726 tls_in.dane_verified = FALSE;
1727 #endif
1728 server_verify_callback_called = FALSE;
1729
1730 if (verify_check_host(&tls_verify_hosts) == OK)
1731 {
1732 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1733 FALSE, verify_callback_server);
1734 if (rc != OK) return rc;
1735 server_verify_optional = FALSE;
1736 }
1737 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1738 {
1739 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1740 TRUE, verify_callback_server);
1741 if (rc != OK) return rc;
1742 server_verify_optional = TRUE;
1743 }
1744
1745 /* Prepare for new connection */
1746
1747 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1748
1749 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1750 *
1751 * With the SSL_clear(), we get strange interoperability bugs with
1752 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1753 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1754 *
1755 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1756 * session shutdown. In this case, we have a brand new object and there's no
1757 * obvious reason to immediately clear it. I'm guessing that this was
1758 * originally added because of incomplete initialisation which the clear fixed,
1759 * in some historic release.
1760 */
1761
1762 /* Set context and tell client to go ahead, except in the case of TLS startup
1763 on connection, where outputting anything now upsets the clients and tends to
1764 make them disconnect. We need to have an explicit fflush() here, to force out
1765 the response. Other smtp_printf() calls do not need it, because in non-TLS
1766 mode, the fflush() happens when smtp_getc() is called. */
1767
1768 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1769 if (!tls_in.on_connect)
1770 {
1771 smtp_printf("220 TLS go ahead\r\n");
1772 fflush(smtp_out);
1773 }
1774
1775 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1776 that the OpenSSL library doesn't. */
1777
1778 SSL_set_wfd(server_ssl, fileno(smtp_out));
1779 SSL_set_rfd(server_ssl, fileno(smtp_in));
1780 SSL_set_accept_state(server_ssl);
1781
1782 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1783
1784 sigalrm_seen = FALSE;
1785 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1786 rc = SSL_accept(server_ssl);
1787 alarm(0);
1788
1789 if (rc <= 0)
1790 {
1791 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1792 if (ERR_get_error() == 0)
1793 log_write(0, LOG_MAIN,
1794 "TLS client disconnected cleanly (rejected our certificate?)");
1795 return FAIL;
1796 }
1797
1798 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1799
1800 /* TLS has been set up. Adjust the input functions to read via TLS,
1801 and initialize things. */
1802
1803 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
1804
1805 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1806 tls_in.cipher = cipherbuf;
1807
1808 DEBUG(D_tls)
1809 {
1810 uschar buf[2048];
1811 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1812 debug_printf("Shared ciphers: %s\n", buf);
1813 }
1814
1815 /* Record the certificate we presented */
1816 {
1817 X509 * crt = SSL_get_certificate(server_ssl);
1818 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1819 }
1820
1821 /* Only used by the server-side tls (tls_in), including tls_getc.
1822 Client-side (tls_out) reads (seem to?) go via
1823 smtp_read_response()/ip_recv().
1824 Hence no need to duplicate for _in and _out.
1825 */
1826 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1827 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1828 ssl_xfer_eof = ssl_xfer_error = 0;
1829
1830 receive_getc = tls_getc;
1831 receive_ungetc = tls_ungetc;
1832 receive_feof = tls_feof;
1833 receive_ferror = tls_ferror;
1834 receive_smtp_buffered = tls_smtp_buffered;
1835
1836 tls_in.active = fileno(smtp_out);
1837 return OK;
1838 }
1839
1840
1841
1842
1843 static int
1844 tls_client_basic_ctx_init(SSL_CTX * ctx,
1845 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
1846 )
1847 {
1848 int rc;
1849 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1850 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1851 the specified host patterns if one of them is defined */
1852
1853 if ( ( !ob->tls_verify_hosts
1854 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
1855 )
1856 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
1857 )
1858 client_verify_optional = FALSE;
1859 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1860 client_verify_optional = TRUE;
1861 else
1862 return OK;
1863
1864 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1865 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1866 return rc;
1867
1868 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1869 {
1870 cbinfo->verify_cert_hostnames =
1871 #ifdef SUPPORT_I18N
1872 string_domain_utf8_to_alabel(host->name, NULL);
1873 #else
1874 host->name;
1875 #endif
1876 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1877 cbinfo->verify_cert_hostnames);
1878 }
1879 return OK;
1880 }
1881
1882
1883 #ifdef EXPERIMENTAL_DANE
1884 static int
1885 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1886 {
1887 dns_record * rr;
1888 dns_scan dnss;
1889 const char * hostnames[2] = { CS host->name, NULL };
1890 int found = 0;
1891
1892 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1893 return tls_error(US"hostnames load", host, NULL);
1894
1895 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1896 rr;
1897 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1898 ) if (rr->type == T_TLSA)
1899 {
1900 uschar * p = rr->data;
1901 uint8_t usage, selector, mtype;
1902 const char * mdname;
1903
1904 usage = *p++;
1905
1906 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1907 if (usage != 2 && usage != 3) continue;
1908
1909 selector = *p++;
1910 mtype = *p++;
1911
1912 switch (mtype)
1913 {
1914 default: continue; /* Only match-types 0, 1, 2 are supported */
1915 case 0: mdname = NULL; break;
1916 case 1: mdname = "sha256"; break;
1917 case 2: mdname = "sha512"; break;
1918 }
1919
1920 found++;
1921 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1922 {
1923 default:
1924 case 0: /* action not taken */
1925 return tls_error(US"tlsa load", host, NULL);
1926 case 1: break;
1927 }
1928
1929 tls_out.tlsa_usage |= 1<<usage;
1930 }
1931
1932 if (found)
1933 return OK;
1934
1935 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1936 return DEFER;
1937 }
1938 #endif /*EXPERIMENTAL_DANE*/
1939
1940
1941
1942 /*************************************************
1943 * Start a TLS session in a client *
1944 *************************************************/
1945
1946 /* Called from the smtp transport after STARTTLS has been accepted.
1947
1948 Argument:
1949 fd the fd of the connection
1950 host connected host (for messages)
1951 addr the first address
1952 tb transport (always smtp)
1953 tlsa_dnsa tlsa lookup, if DANE, else null
1954
1955 Returns: OK on success
1956 FAIL otherwise - note that tls_error() will not give DEFER
1957 because this is not a server
1958 */
1959
1960 int
1961 tls_client_start(int fd, host_item *host, address_item *addr,
1962 transport_instance *tb
1963 #ifdef EXPERIMENTAL_DANE
1964 , dns_answer * tlsa_dnsa
1965 #endif
1966 )
1967 {
1968 smtp_transport_options_block * ob =
1969 (smtp_transport_options_block *)tb->options_block;
1970 static uschar peerdn[256];
1971 uschar * expciphers;
1972 int rc;
1973 static uschar cipherbuf[256];
1974
1975 #ifndef DISABLE_OCSP
1976 BOOL request_ocsp = FALSE;
1977 BOOL require_ocsp = FALSE;
1978 #endif
1979
1980 #ifdef EXPERIMENTAL_DANE
1981 tls_out.tlsa_usage = 0;
1982 #endif
1983
1984 #ifndef DISABLE_OCSP
1985 {
1986 # ifdef EXPERIMENTAL_DANE
1987 if ( tlsa_dnsa
1988 && ob->hosts_request_ocsp[0] == '*'
1989 && ob->hosts_request_ocsp[1] == '\0'
1990 )
1991 {
1992 /* Unchanged from default. Use a safer one under DANE */
1993 request_ocsp = TRUE;
1994 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1995 " {= {4}{$tls_out_tlsa_usage}} } "
1996 " {*}{}}";
1997 }
1998 # endif
1999
2000 if ((require_ocsp =
2001 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
2002 request_ocsp = TRUE;
2003 else
2004 # ifdef EXPERIMENTAL_DANE
2005 if (!request_ocsp)
2006 # endif
2007 request_ocsp =
2008 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2009 }
2010 #endif
2011
2012 rc = tls_init(&client_ctx, host, NULL,
2013 ob->tls_certificate, ob->tls_privatekey,
2014 #ifndef DISABLE_OCSP
2015 (void *)(long)request_ocsp,
2016 #endif
2017 addr, &client_static_cbinfo);
2018 if (rc != OK) return rc;
2019
2020 tls_out.certificate_verified = FALSE;
2021 client_verify_callback_called = FALSE;
2022
2023 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2024 &expciphers))
2025 return FAIL;
2026
2027 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2028 are separated by underscores. So that I can use either form in my tests, and
2029 also for general convenience, we turn underscores into hyphens here. */
2030
2031 if (expciphers != NULL)
2032 {
2033 uschar *s = expciphers;
2034 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2035 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2036 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
2037 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
2038 }
2039
2040 #ifdef EXPERIMENTAL_DANE
2041 if (tlsa_dnsa)
2042 {
2043 SSL_CTX_set_verify(client_ctx,
2044 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2045 verify_callback_client_dane);
2046
2047 if (!DANESSL_library_init())
2048 return tls_error(US"library init", host, NULL);
2049 if (DANESSL_CTX_init(client_ctx) <= 0)
2050 return tls_error(US"context init", host, NULL);
2051 }
2052 else
2053
2054 #endif
2055
2056 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
2057 != OK)
2058 return rc;
2059
2060 if ((client_ssl = SSL_new(client_ctx)) == NULL)
2061 return tls_error(US"SSL_new", host, NULL);
2062 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
2063 SSL_set_fd(client_ssl, fd);
2064 SSL_set_connect_state(client_ssl);
2065
2066 if (ob->tls_sni)
2067 {
2068 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
2069 return FAIL;
2070 if (tls_out.sni == NULL)
2071 {
2072 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2073 }
2074 else if (!Ustrlen(tls_out.sni))
2075 tls_out.sni = NULL;
2076 else
2077 {
2078 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2079 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
2080 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
2081 #else
2082 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2083 tls_out.sni);
2084 #endif
2085 }
2086 }
2087
2088 #ifdef EXPERIMENTAL_DANE
2089 if (tlsa_dnsa)
2090 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
2091 return rc;
2092 #endif
2093
2094 #ifndef DISABLE_OCSP
2095 /* Request certificate status at connection-time. If the server
2096 does OCSP stapling we will get the callback (set in tls_init()) */
2097 # ifdef EXPERIMENTAL_DANE
2098 if (request_ocsp)
2099 {
2100 const uschar * s;
2101 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2102 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2103 )
2104 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2105 this means we avoid the OCSP request, we wasted the setup
2106 cost in tls_init(). */
2107 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2108 request_ocsp = require_ocsp
2109 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
2110 }
2111 }
2112 # endif
2113
2114 if (request_ocsp)
2115 {
2116 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
2117 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2118 tls_out.ocsp = OCSP_NOT_RESP;
2119 }
2120 #endif
2121
2122 #ifndef DISABLE_EVENT
2123 client_static_cbinfo->event_action = tb->event_action;
2124 #endif
2125
2126 /* There doesn't seem to be a built-in timeout on connection. */
2127
2128 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2129 sigalrm_seen = FALSE;
2130 alarm(ob->command_timeout);
2131 rc = SSL_connect(client_ssl);
2132 alarm(0);
2133
2134 #ifdef EXPERIMENTAL_DANE
2135 if (tlsa_dnsa)
2136 DANESSL_cleanup(client_ssl);
2137 #endif
2138
2139 if (rc <= 0)
2140 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
2141
2142 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2143
2144 peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
2145
2146 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2147 tls_out.cipher = cipherbuf;
2148
2149 /* Record the certificate we presented */
2150 {
2151 X509 * crt = SSL_get_certificate(client_ssl);
2152 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2153 }
2154
2155 tls_out.active = fd;
2156 return OK;
2157 }
2158
2159
2160
2161
2162
2163 /*************************************************
2164 * TLS version of getc *
2165 *************************************************/
2166
2167 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2168 it refills the buffer via the SSL reading function.
2169
2170 Arguments: none
2171 Returns: the next character or EOF
2172
2173 Only used by the server-side TLS.
2174 */
2175
2176 int
2177 tls_getc(void)
2178 {
2179 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2180 {
2181 int error;
2182 int inbytes;
2183
2184 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2185 ssl_xfer_buffer, ssl_xfer_buffer_size);
2186
2187 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2188 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2189 error = SSL_get_error(server_ssl, inbytes);
2190 alarm(0);
2191
2192 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2193 closed down, not that the socket itself has been closed down. Revert to
2194 non-SSL handling. */
2195
2196 if (error == SSL_ERROR_ZERO_RETURN)
2197 {
2198 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2199
2200 receive_getc = smtp_getc;
2201 receive_ungetc = smtp_ungetc;
2202 receive_feof = smtp_feof;
2203 receive_ferror = smtp_ferror;
2204 receive_smtp_buffered = smtp_buffered;
2205
2206 SSL_free(server_ssl);
2207 server_ssl = NULL;
2208 tls_in.active = -1;
2209 tls_in.bits = 0;
2210 tls_in.cipher = NULL;
2211 tls_in.peerdn = NULL;
2212 tls_in.sni = NULL;
2213
2214 return smtp_getc();
2215 }
2216
2217 /* Handle genuine errors */
2218
2219 else if (error == SSL_ERROR_SSL)
2220 {
2221 ERR_error_string(ERR_get_error(), ssl_errstring);
2222 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2223 ssl_xfer_error = 1;
2224 return EOF;
2225 }
2226
2227 else if (error != SSL_ERROR_NONE)
2228 {
2229 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2230 ssl_xfer_error = 1;
2231 return EOF;
2232 }
2233
2234 #ifndef DISABLE_DKIM
2235 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2236 #endif
2237 ssl_xfer_buffer_hwm = inbytes;
2238 ssl_xfer_buffer_lwm = 0;
2239 }
2240
2241 /* Something in the buffer; return next uschar */
2242
2243 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2244 }
2245
2246
2247
2248 /*************************************************
2249 * Read bytes from TLS channel *
2250 *************************************************/
2251
2252 /*
2253 Arguments:
2254 buff buffer of data
2255 len size of buffer
2256
2257 Returns: the number of bytes read
2258 -1 after a failed read
2259
2260 Only used by the client-side TLS.
2261 */
2262
2263 int
2264 tls_read(BOOL is_server, uschar *buff, size_t len)
2265 {
2266 SSL *ssl = is_server ? server_ssl : client_ssl;
2267 int inbytes;
2268 int error;
2269
2270 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2271 buff, (unsigned int)len);
2272
2273 inbytes = SSL_read(ssl, CS buff, len);
2274 error = SSL_get_error(ssl, inbytes);
2275
2276 if (error == SSL_ERROR_ZERO_RETURN)
2277 {
2278 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2279 return -1;
2280 }
2281 else if (error != SSL_ERROR_NONE)
2282 {
2283 return -1;
2284 }
2285
2286 return inbytes;
2287 }
2288
2289
2290
2291
2292
2293 /*************************************************
2294 * Write bytes down TLS channel *
2295 *************************************************/
2296
2297 /*
2298 Arguments:
2299 is_server channel specifier
2300 buff buffer of data
2301 len number of bytes
2302
2303 Returns: the number of bytes after a successful write,
2304 -1 after a failed write
2305
2306 Used by both server-side and client-side TLS.
2307 */
2308
2309 int
2310 tls_write(BOOL is_server, const uschar *buff, size_t len)
2311 {
2312 int outbytes;
2313 int error;
2314 int left = len;
2315 SSL *ssl = is_server ? server_ssl : client_ssl;
2316
2317 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2318 while (left > 0)
2319 {
2320 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2321 outbytes = SSL_write(ssl, CS buff, left);
2322 error = SSL_get_error(ssl, outbytes);
2323 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2324 switch (error)
2325 {
2326 case SSL_ERROR_SSL:
2327 ERR_error_string(ERR_get_error(), ssl_errstring);
2328 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2329 return -1;
2330
2331 case SSL_ERROR_NONE:
2332 left -= outbytes;
2333 buff += outbytes;
2334 break;
2335
2336 case SSL_ERROR_ZERO_RETURN:
2337 log_write(0, LOG_MAIN, "SSL channel closed on write");
2338 return -1;
2339
2340 case SSL_ERROR_SYSCALL:
2341 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2342 sender_fullhost ? sender_fullhost : US"<unknown>",
2343 strerror(errno));
2344
2345 default:
2346 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2347 return -1;
2348 }
2349 }
2350 return len;
2351 }
2352
2353
2354
2355 /*************************************************
2356 * Close down a TLS session *
2357 *************************************************/
2358
2359 /* This is also called from within a delivery subprocess forked from the
2360 daemon, to shut down the TLS library, without actually doing a shutdown (which
2361 would tamper with the SSL session in the parent process).
2362
2363 Arguments: TRUE if SSL_shutdown is to be called
2364 Returns: nothing
2365
2366 Used by both server-side and client-side TLS.
2367 */
2368
2369 void
2370 tls_close(BOOL is_server, BOOL shutdown)
2371 {
2372 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2373 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2374
2375 if (*fdp < 0) return; /* TLS was not active */
2376
2377 if (shutdown)
2378 {
2379 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2380 SSL_shutdown(*sslp);
2381 }
2382
2383 SSL_free(*sslp);
2384 *sslp = NULL;
2385
2386 *fdp = -1;
2387 }
2388
2389
2390
2391
2392 /*************************************************
2393 * Let tls_require_ciphers be checked at startup *
2394 *************************************************/
2395
2396 /* The tls_require_ciphers option, if set, must be something which the
2397 library can parse.
2398
2399 Returns: NULL on success, or error message
2400 */
2401
2402 uschar *
2403 tls_validate_require_cipher(void)
2404 {
2405 SSL_CTX *ctx;
2406 uschar *s, *expciphers, *err;
2407
2408 /* this duplicates from tls_init(), we need a better "init just global
2409 state, for no specific purpose" singleton function of our own */
2410
2411 SSL_load_error_strings();
2412 OpenSSL_add_ssl_algorithms();
2413 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2414 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2415 list of available digests. */
2416 EVP_add_digest(EVP_sha256());
2417 #endif
2418
2419 if (!(tls_require_ciphers && *tls_require_ciphers))
2420 return NULL;
2421
2422 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2423 return US"failed to expand tls_require_ciphers";
2424
2425 if (!(expciphers && *expciphers))
2426 return NULL;
2427
2428 /* normalisation ripped from above */
2429 s = expciphers;
2430 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2431
2432 err = NULL;
2433
2434 ctx = SSL_CTX_new(SSLv23_server_method());
2435 if (!ctx)
2436 {
2437 ERR_error_string(ERR_get_error(), ssl_errstring);
2438 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2439 }
2440
2441 DEBUG(D_tls)
2442 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2443
2444 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2445 {
2446 ERR_error_string(ERR_get_error(), ssl_errstring);
2447 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2448 }
2449
2450 SSL_CTX_free(ctx);
2451
2452 return err;
2453 }
2454
2455
2456
2457
2458 /*************************************************
2459 * Report the library versions. *
2460 *************************************************/
2461
2462 /* There have historically been some issues with binary compatibility in
2463 OpenSSL libraries; if Exim (like many other applications) is built against
2464 one version of OpenSSL but the run-time linker picks up another version,
2465 it can result in serious failures, including crashing with a SIGSEGV. So
2466 report the version found by the compiler and the run-time version.
2467
2468 Note: some OS vendors backport security fixes without changing the version
2469 number/string, and the version date remains unchanged. The _build_ date
2470 will change, so we can more usefully assist with version diagnosis by also
2471 reporting the build date.
2472
2473 Arguments: a FILE* to print the results to
2474 Returns: nothing
2475 */
2476
2477 void
2478 tls_version_report(FILE *f)
2479 {
2480 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2481 " Runtime: %s\n"
2482 " : %s\n",
2483 OPENSSL_VERSION_TEXT,
2484 SSLeay_version(SSLEAY_VERSION),
2485 SSLeay_version(SSLEAY_BUILT_ON));
2486 /* third line is 38 characters for the %s and the line is 73 chars long;
2487 the OpenSSL output includes a "built on: " prefix already. */
2488 }
2489
2490
2491
2492
2493 /*************************************************
2494 * Random number generation *
2495 *************************************************/
2496
2497 /* Pseudo-random number generation. The result is not expected to be
2498 cryptographically strong but not so weak that someone will shoot themselves
2499 in the foot using it as a nonce in input in some email header scheme or
2500 whatever weirdness they'll twist this into. The result should handle fork()
2501 and avoid repeating sequences. OpenSSL handles that for us.
2502
2503 Arguments:
2504 max range maximum
2505 Returns a random number in range [0, max-1]
2506 */
2507
2508 int
2509 vaguely_random_number(int max)
2510 {
2511 unsigned int r;
2512 int i, needed_len;
2513 static pid_t pidlast = 0;
2514 pid_t pidnow;
2515 uschar *p;
2516 uschar smallbuf[sizeof(r)];
2517
2518 if (max <= 1)
2519 return 0;
2520
2521 pidnow = getpid();
2522 if (pidnow != pidlast)
2523 {
2524 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2525 is unique for each thread", this doesn't apparently apply across processes,
2526 so our own warning from vaguely_random_number_fallback() applies here too.
2527 Fix per PostgreSQL. */
2528 if (pidlast != 0)
2529 RAND_cleanup();
2530 pidlast = pidnow;
2531 }
2532
2533 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2534 if (!RAND_status())
2535 {
2536 randstuff r;
2537 gettimeofday(&r.tv, NULL);
2538 r.p = getpid();
2539
2540 RAND_seed((uschar *)(&r), sizeof(r));
2541 }
2542 /* We're after pseudo-random, not random; if we still don't have enough data
2543 in the internal PRNG then our options are limited. We could sleep and hope
2544 for entropy to come along (prayer technique) but if the system is so depleted
2545 in the first place then something is likely to just keep taking it. Instead,
2546 we'll just take whatever little bit of pseudo-random we can still manage to
2547 get. */
2548
2549 needed_len = sizeof(r);
2550 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2551 asked for a number less than 10. */
2552 for (r = max, i = 0; r; ++i)
2553 r >>= 1;
2554 i = (i + 7) / 8;
2555 if (i < needed_len)
2556 needed_len = i;
2557
2558 /* We do not care if crypto-strong */
2559 i = RAND_pseudo_bytes(smallbuf, needed_len);
2560 if (i < 0)
2561 {
2562 DEBUG(D_all)
2563 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2564 return vaguely_random_number_fallback(max);
2565 }
2566
2567 r = 0;
2568 for (p = smallbuf; needed_len; --needed_len, ++p)
2569 {
2570 r *= 256;
2571 r += *p;
2572 }
2573
2574 /* We don't particularly care about weighted results; if someone wants
2575 smooth distribution and cares enough then they should submit a patch then. */
2576 return r % max;
2577 }
2578
2579
2580
2581
2582 /*************************************************
2583 * OpenSSL option parse *
2584 *************************************************/
2585
2586 /* Parse one option for tls_openssl_options_parse below
2587
2588 Arguments:
2589 name one option name
2590 value place to store a value for it
2591 Returns success or failure in parsing
2592 */
2593
2594 struct exim_openssl_option {
2595 uschar *name;
2596 long value;
2597 };
2598 /* We could use a macro to expand, but we need the ifdef and not all the
2599 options document which version they were introduced in. Policylet: include
2600 all options unless explicitly for DTLS, let the administrator choose which
2601 to apply.
2602
2603 This list is current as of:
2604 ==> 1.0.1b <==
2605 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2606 */
2607 static struct exim_openssl_option exim_openssl_options[] = {
2608 /* KEEP SORTED ALPHABETICALLY! */
2609 #ifdef SSL_OP_ALL
2610 { US"all", SSL_OP_ALL },
2611 #endif
2612 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2613 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2614 #endif
2615 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2616 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2617 #endif
2618 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2619 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2620 #endif
2621 #ifdef SSL_OP_EPHEMERAL_RSA
2622 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2623 #endif
2624 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2625 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2626 #endif
2627 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2628 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2629 #endif
2630 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2631 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2632 #endif
2633 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2634 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2635 #endif
2636 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2637 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2638 #endif
2639 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2640 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2641 #endif
2642 #ifdef SSL_OP_NO_COMPRESSION
2643 { US"no_compression", SSL_OP_NO_COMPRESSION },
2644 #endif
2645 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2646 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2647 #endif
2648 #ifdef SSL_OP_NO_SSLv2
2649 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2650 #endif
2651 #ifdef SSL_OP_NO_SSLv3
2652 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2653 #endif
2654 #ifdef SSL_OP_NO_TICKET
2655 { US"no_ticket", SSL_OP_NO_TICKET },
2656 #endif
2657 #ifdef SSL_OP_NO_TLSv1
2658 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2659 #endif
2660 #ifdef SSL_OP_NO_TLSv1_1
2661 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2662 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2663 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2664 #else
2665 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2666 #endif
2667 #endif
2668 #ifdef SSL_OP_NO_TLSv1_2
2669 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2670 #endif
2671 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2672 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2673 #endif
2674 #ifdef SSL_OP_SINGLE_DH_USE
2675 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2676 #endif
2677 #ifdef SSL_OP_SINGLE_ECDH_USE
2678 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2679 #endif
2680 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2681 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2682 #endif
2683 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2684 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2685 #endif
2686 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2687 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2688 #endif
2689 #ifdef SSL_OP_TLS_D5_BUG
2690 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2691 #endif
2692 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2693 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2694 #endif
2695 };
2696 static int exim_openssl_options_size =
2697 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2698
2699
2700 static BOOL
2701 tls_openssl_one_option_parse(uschar *name, long *value)
2702 {
2703 int first = 0;
2704 int last = exim_openssl_options_size;
2705 while (last > first)
2706 {
2707 int middle = (first + last)/2;
2708 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2709 if (c == 0)
2710 {
2711 *value = exim_openssl_options[middle].value;
2712 return TRUE;
2713 }
2714 else if (c > 0)
2715 first = middle + 1;
2716 else
2717 last = middle;
2718 }
2719 return FALSE;
2720 }
2721
2722
2723
2724
2725 /*************************************************
2726 * OpenSSL option parsing logic *
2727 *************************************************/
2728
2729 /* OpenSSL has a number of compatibility options which an administrator might
2730 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2731 we look like log_selector.
2732
2733 Arguments:
2734 option_spec the administrator-supplied string of options
2735 results ptr to long storage for the options bitmap
2736 Returns success or failure
2737 */
2738
2739 BOOL
2740 tls_openssl_options_parse(uschar *option_spec, long *results)
2741 {
2742 long result, item;
2743 uschar *s, *end;
2744 uschar keep_c;
2745 BOOL adding, item_parsed;
2746
2747 result = 0L;
2748 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2749 * from default because it increases BEAST susceptibility. */
2750 #ifdef SSL_OP_NO_SSLv2
2751 result |= SSL_OP_NO_SSLv2;
2752 #endif
2753 #ifdef SSL_OP_SINGLE_DH_USE
2754 result |= SSL_OP_SINGLE_DH_USE;
2755 #endif
2756
2757 if (option_spec == NULL)
2758 {
2759 *results = result;
2760 return TRUE;
2761 }
2762
2763 for (s=option_spec; *s != '\0'; /**/)
2764 {
2765 while (isspace(*s)) ++s;
2766 if (*s == '\0')
2767 break;
2768 if (*s != '+' && *s != '-')
2769 {
2770 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2771 "+ or - expected but found \"%s\"\n", s);
2772 return FALSE;
2773 }
2774 adding = *s++ == '+';
2775 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2776 keep_c = *end;
2777 *end = '\0';
2778 item_parsed = tls_openssl_one_option_parse(s, &item);
2779 if (!item_parsed)
2780 {
2781 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2782 return FALSE;
2783 }
2784 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2785 adding ? "adding" : "removing", result, item, s);
2786 if (adding)
2787 result |= item;
2788 else
2789 result &= ~item;
2790 *end = keep_c;
2791 s = end;
2792 }
2793
2794 *results = result;
2795 return TRUE;
2796 }
2797
2798 /* vi: aw ai sw=2
2799 */
2800 /* End of tls-openssl.c */