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OpenSSL: Enhance connect/accept-time debug
[exim.git] / src / src / tls-openssl.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
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 SUPPORT_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 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
45 # define EXIM_HAVE_RSA_GENKEY_EX
46 #endif
47 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
48 # define EXIM_HAVE_OCSP_RESP_COUNT
49 #else
50 # define EXIM_HAVE_EPHEM_RSA_KEX
51 # define EXIM_HAVE_RAND_PSEUDO
52 #endif
53 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
54 # define EXIM_HAVE_SHA256
55 #endif
56
57 /*
58 * X509_check_host provides sane certificate hostname checking, but was added
59 * to OpenSSL late, after other projects forked off the code-base. So in
60 * addition to guarding against the base version number, beware that LibreSSL
61 * does not (at this time) support this function.
62 *
63 * If LibreSSL gains a different API, perhaps via libtls, then we'll probably
64 * opt to disentangle and ask a LibreSSL user to provide glue for a third
65 * crypto provider for libtls instead of continuing to tie the OpenSSL glue
66 * into even twistier knots. If LibreSSL gains the same API, we can just
67 * change this guard and punt the issue for a while longer.
68 */
69 #ifndef LIBRESSL_VERSION_NUMBER
70 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
71 # define EXIM_HAVE_OPENSSL_CHECKHOST
72 # define EXIM_HAVE_OPENSSL_DH_BITS
73 # define EXIM_HAVE_OPENSSL_TLS_METHOD
74 # endif
75 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
76 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
77 # define EXIM_HAVE_OPENSSL_CHECKHOST
78 # endif
79 #endif
80
81 #if !defined(LIBRESSL_VERSION_NUMBER) \
82 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
83 # if !defined(OPENSSL_NO_ECDH)
84 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
85 # define EXIM_HAVE_ECDH
86 # endif
87 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
88 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
89 # endif
90 # endif
91 #endif
92
93 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
94 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
95 # define DISABLE_OCSP
96 #endif
97
98 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
99 # include <openssl/x509v3.h>
100 #endif
101
102 /*************************************************
103 * OpenSSL option parse *
104 *************************************************/
105
106 typedef struct exim_openssl_option {
107 uschar *name;
108 long value;
109 } exim_openssl_option;
110 /* We could use a macro to expand, but we need the ifdef and not all the
111 options document which version they were introduced in. Policylet: include
112 all options unless explicitly for DTLS, let the administrator choose which
113 to apply.
114
115 This list is current as of:
116 ==> 1.0.1b <==
117 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
118 Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev
119 */
120 static exim_openssl_option exim_openssl_options[] = {
121 /* KEEP SORTED ALPHABETICALLY! */
122 #ifdef SSL_OP_ALL
123 { US"all", SSL_OP_ALL },
124 #endif
125 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
126 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
127 #endif
128 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
129 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
130 #endif
131 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
132 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
133 #endif
134 #ifdef SSL_OP_EPHEMERAL_RSA
135 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
136 #endif
137 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
138 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
139 #endif
140 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
141 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
142 #endif
143 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
144 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
145 #endif
146 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
147 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
148 #endif
149 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
150 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
151 #endif
152 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
153 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
154 #endif
155 #ifdef SSL_OP_NO_COMPRESSION
156 { US"no_compression", SSL_OP_NO_COMPRESSION },
157 #endif
158 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
159 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
160 #endif
161 #ifdef SSL_OP_NO_SSLv2
162 { US"no_sslv2", SSL_OP_NO_SSLv2 },
163 #endif
164 #ifdef SSL_OP_NO_SSLv3
165 { US"no_sslv3", SSL_OP_NO_SSLv3 },
166 #endif
167 #ifdef SSL_OP_NO_TICKET
168 { US"no_ticket", SSL_OP_NO_TICKET },
169 #endif
170 #ifdef SSL_OP_NO_TLSv1
171 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
172 #endif
173 #ifdef SSL_OP_NO_TLSv1_1
174 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
175 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
176 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
177 #else
178 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
179 #endif
180 #endif
181 #ifdef SSL_OP_NO_TLSv1_2
182 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
183 #endif
184 #ifdef SSL_OP_NO_TLSv1_3
185 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
186 #endif
187 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
188 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
189 #endif
190 #ifdef SSL_OP_SINGLE_DH_USE
191 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
192 #endif
193 #ifdef SSL_OP_SINGLE_ECDH_USE
194 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
195 #endif
196 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
197 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
198 #endif
199 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
200 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
201 #endif
202 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
203 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
204 #endif
205 #ifdef SSL_OP_TLS_D5_BUG
206 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
207 #endif
208 #ifdef SSL_OP_TLS_ROLLBACK_BUG
209 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
210 #endif
211 };
212
213 #ifndef MACRO_PREDEF
214 static int exim_openssl_options_size = nelem(exim_openssl_options);
215 #endif
216
217 #ifdef MACRO_PREDEF
218 void
219 options_tls(void)
220 {
221 struct exim_openssl_option * o;
222 uschar buf[64];
223
224 for (o = exim_openssl_options;
225 o < exim_openssl_options + nelem(exim_openssl_options); o++)
226 {
227 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
228 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
229
230 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
231 builtin_macro_create(buf);
232 }
233 }
234 #else
235
236 /******************************************************************************/
237
238 /* Structure for collecting random data for seeding. */
239
240 typedef struct randstuff {
241 struct timeval tv;
242 pid_t p;
243 } randstuff;
244
245 /* Local static variables */
246
247 static BOOL client_verify_callback_called = FALSE;
248 static BOOL server_verify_callback_called = FALSE;
249 static const uschar *sid_ctx = US"exim";
250
251 /* We have three different contexts to care about.
252
253 Simple case: client, `client_ctx`
254 As a client, we can be doing a callout or cut-through delivery while receiving
255 a message. So we have a client context, which should have options initialised
256 from the SMTP Transport. We may also concurrently want to make TLS connections
257 to utility daemons, so client-contexts are allocated and passed around in call
258 args rather than using a gobal.
259
260 Server:
261 There are two cases: with and without ServerNameIndication from the client.
262 Given TLS SNI, we can be using different keys, certs and various other
263 configuration settings, because they're re-expanded with $tls_sni set. This
264 allows vhosting with TLS. This SNI is sent in the handshake.
265 A client might not send SNI, so we need a fallback, and an initial setup too.
266 So as a server, we start out using `server_ctx`.
267 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
268 `server_sni` from `server_ctx` and then initialise settings by re-expanding
269 configuration.
270 */
271
272 typedef struct {
273 SSL_CTX * ctx;
274 SSL * ssl;
275 } exim_openssl_client_tls_ctx;
276
277 static SSL_CTX *server_ctx = NULL;
278 static SSL *server_ssl = NULL;
279
280 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
281 static SSL_CTX *server_sni = NULL;
282 #endif
283
284 static char ssl_errstring[256];
285
286 static int ssl_session_timeout = 200;
287 static BOOL client_verify_optional = FALSE;
288 static BOOL server_verify_optional = FALSE;
289
290 static BOOL reexpand_tls_files_for_sni = FALSE;
291
292
293 typedef struct tls_ext_ctx_cb {
294 uschar *certificate;
295 uschar *privatekey;
296 BOOL is_server;
297 #ifndef DISABLE_OCSP
298 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
299 union {
300 struct {
301 uschar *file;
302 uschar *file_expanded;
303 OCSP_RESPONSE *response;
304 } server;
305 struct {
306 X509_STORE *verify_store; /* non-null if status requested */
307 BOOL verify_required;
308 } client;
309 } u_ocsp;
310 #endif
311 uschar *dhparam;
312 /* these are cached from first expand */
313 uschar *server_cipher_list;
314 /* only passed down to tls_error: */
315 host_item *host;
316 const uschar * verify_cert_hostnames;
317 #ifndef DISABLE_EVENT
318 uschar * event_action;
319 #endif
320 } tls_ext_ctx_cb;
321
322 /* should figure out a cleanup of API to handle state preserved per
323 implementation, for various reasons, which can be void * in the APIs.
324 For now, we hack around it. */
325 tls_ext_ctx_cb *client_static_cbinfo = NULL;
326 tls_ext_ctx_cb *server_static_cbinfo = NULL;
327
328 static int
329 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
330 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
331
332 /* Callbacks */
333 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
334 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
335 #endif
336 #ifndef DISABLE_OCSP
337 static int tls_server_stapling_cb(SSL *s, void *arg);
338 #endif
339
340
341 /*************************************************
342 * Handle TLS error *
343 *************************************************/
344
345 /* Called from lots of places when errors occur before actually starting to do
346 the TLS handshake, that is, while the session is still in clear. Always returns
347 DEFER for a server and FAIL for a client so that most calls can use "return
348 tls_error(...)" to do this processing and then give an appropriate return. A
349 single function is used for both server and client, because it is called from
350 some shared functions.
351
352 Argument:
353 prefix text to include in the logged error
354 host NULL if setting up a server;
355 the connected host if setting up a client
356 msg error message or NULL if we should ask OpenSSL
357 errstr pointer to output error message
358
359 Returns: OK/DEFER/FAIL
360 */
361
362 static int
363 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
364 {
365 if (!msg)
366 {
367 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
368 msg = US ssl_errstring;
369 }
370
371 if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg);
372 return host ? FAIL : DEFER;
373 }
374
375
376
377 /*************************************************
378 * Callback to generate RSA key *
379 *************************************************/
380
381 /*
382 Arguments:
383 s SSL connection (not used)
384 export not used
385 keylength keylength
386
387 Returns: pointer to generated key
388 */
389
390 static RSA *
391 rsa_callback(SSL *s, int export, int keylength)
392 {
393 RSA *rsa_key;
394 #ifdef EXIM_HAVE_RSA_GENKEY_EX
395 BIGNUM *bn = BN_new();
396 #endif
397
398 export = export; /* Shut picky compilers up */
399 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
400
401 #ifdef EXIM_HAVE_RSA_GENKEY_EX
402 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
403 || !(rsa_key = RSA_new())
404 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
405 )
406 #else
407 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
408 #endif
409
410 {
411 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
412 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
413 ssl_errstring);
414 return NULL;
415 }
416 return rsa_key;
417 }
418
419
420
421 /* Extreme debug
422 #ifndef DISABLE_OCSP
423 void
424 x509_store_dump_cert_s_names(X509_STORE * store)
425 {
426 STACK_OF(X509_OBJECT) * roots= store->objs;
427 int i;
428 static uschar name[256];
429
430 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
431 {
432 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
433 if(tmp_obj->type == X509_LU_X509)
434 {
435 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
436 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
437 {
438 name[sizeof(name)-1] = '\0';
439 debug_printf(" %s\n", name);
440 }
441 }
442 }
443 }
444 #endif
445 */
446
447
448 #ifndef DISABLE_EVENT
449 static int
450 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
451 BOOL *calledp, const BOOL *optionalp, const uschar * what)
452 {
453 uschar * ev;
454 uschar * yield;
455 X509 * old_cert;
456
457 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
458 if (ev)
459 {
460 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
461 old_cert = tlsp->peercert;
462 tlsp->peercert = X509_dup(cert);
463 /* NB we do not bother setting peerdn */
464 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
465 {
466 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
467 "depth=%d cert=%s: %s",
468 tlsp == &tls_out ? deliver_host_address : sender_host_address,
469 what, depth, dn, yield);
470 *calledp = TRUE;
471 if (!*optionalp)
472 {
473 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
474 return 1; /* reject (leaving peercert set) */
475 }
476 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
477 "(host in tls_try_verify_hosts)\n");
478 }
479 X509_free(tlsp->peercert);
480 tlsp->peercert = old_cert;
481 }
482 return 0;
483 }
484 #endif
485
486 /*************************************************
487 * Callback for verification *
488 *************************************************/
489
490 /* The SSL library does certificate verification if set up to do so. This
491 callback has the current yes/no state is in "state". If verification succeeded,
492 we set the certificate-verified flag. If verification failed, what happens
493 depends on whether the client is required to present a verifiable certificate
494 or not.
495
496 If verification is optional, we change the state to yes, but still log the
497 verification error. For some reason (it really would help to have proper
498 documentation of OpenSSL), this callback function then gets called again, this
499 time with state = 1. We must take care not to set the private verified flag on
500 the second time through.
501
502 Note: this function is not called if the client fails to present a certificate
503 when asked. We get here only if a certificate has been received. Handling of
504 optional verification for this case is done when requesting SSL to verify, by
505 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
506
507 May be called multiple times for different issues with a certificate, even
508 for a given "depth" in the certificate chain.
509
510 Arguments:
511 preverify_ok current yes/no state as 1/0
512 x509ctx certificate information.
513 tlsp per-direction (client vs. server) support data
514 calledp has-been-called flag
515 optionalp verification-is-optional flag
516
517 Returns: 0 if verification should fail, otherwise 1
518 */
519
520 static int
521 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
522 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
523 {
524 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
525 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
526 uschar dn[256];
527
528 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
529 {
530 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
531 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
532 tlsp == &tls_out ? deliver_host_address : sender_host_address);
533 return 0;
534 }
535 dn[sizeof(dn)-1] = '\0';
536
537 if (preverify_ok == 0)
538 {
539 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
540 *verify_mode, sender_host_address)
541 : US"";
542 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
543 tlsp == &tls_out ? deliver_host_address : sender_host_address,
544 extra, depth,
545 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
546 *calledp = TRUE;
547 if (!*optionalp)
548 {
549 if (!tlsp->peercert)
550 tlsp->peercert = X509_dup(cert); /* record failing cert */
551 return 0; /* reject */
552 }
553 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
554 "tls_try_verify_hosts)\n");
555 }
556
557 else if (depth != 0)
558 {
559 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
560 #ifndef DISABLE_OCSP
561 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
562 { /* client, wanting stapling */
563 /* Add the server cert's signing chain as the one
564 for the verification of the OCSP stapled information. */
565
566 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
567 cert))
568 ERR_clear_error();
569 sk_X509_push(client_static_cbinfo->verify_stack, cert);
570 }
571 #endif
572 #ifndef DISABLE_EVENT
573 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
574 return 0; /* reject, with peercert set */
575 #endif
576 }
577 else
578 {
579 const uschar * verify_cert_hostnames;
580
581 if ( tlsp == &tls_out
582 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
583 /* client, wanting hostname check */
584 {
585
586 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
587 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
588 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
589 # endif
590 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
591 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
592 # endif
593 int sep = 0;
594 const uschar * list = verify_cert_hostnames;
595 uschar * name;
596 int rc;
597 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
598 if ((rc = X509_check_host(cert, CCS name, 0,
599 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
600 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
601 NULL)))
602 {
603 if (rc < 0)
604 {
605 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
606 tlsp == &tls_out ? deliver_host_address : sender_host_address);
607 name = NULL;
608 }
609 break;
610 }
611 if (!name)
612 #else
613 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
614 #endif
615 {
616 uschar * extra = verify_mode
617 ? string_sprintf(" (during %c-verify for [%s])",
618 *verify_mode, sender_host_address)
619 : US"";
620 log_write(0, LOG_MAIN,
621 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
622 tlsp == &tls_out ? deliver_host_address : sender_host_address,
623 extra, dn, verify_cert_hostnames);
624 *calledp = TRUE;
625 if (!*optionalp)
626 {
627 if (!tlsp->peercert)
628 tlsp->peercert = X509_dup(cert); /* record failing cert */
629 return 0; /* reject */
630 }
631 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
632 "tls_try_verify_hosts)\n");
633 }
634 }
635
636 #ifndef DISABLE_EVENT
637 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
638 return 0; /* reject, with peercert set */
639 #endif
640
641 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
642 *calledp ? "" : " authenticated", dn);
643 if (!*calledp) tlsp->certificate_verified = TRUE;
644 *calledp = TRUE;
645 }
646
647 return 1; /* accept, at least for this level */
648 }
649
650 static int
651 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
652 {
653 return verify_callback(preverify_ok, x509ctx, &tls_out,
654 &client_verify_callback_called, &client_verify_optional);
655 }
656
657 static int
658 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
659 {
660 return verify_callback(preverify_ok, x509ctx, &tls_in,
661 &server_verify_callback_called, &server_verify_optional);
662 }
663
664
665 #ifdef SUPPORT_DANE
666
667 /* This gets called *by* the dane library verify callback, which interposes
668 itself.
669 */
670 static int
671 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
672 {
673 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
674 uschar dn[256];
675 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
676 #ifndef DISABLE_EVENT
677 BOOL dummy_called, optional = FALSE;
678 #endif
679
680 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
681 {
682 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
683 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
684 deliver_host_address);
685 return 0;
686 }
687 dn[sizeof(dn)-1] = '\0';
688
689 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
690 preverify_ok ? "ok":"BAD", depth, dn);
691
692 #ifndef DISABLE_EVENT
693 if (verify_event(&tls_out, cert, depth, dn,
694 &dummy_called, &optional, US"DANE"))
695 return 0; /* reject, with peercert set */
696 #endif
697
698 if (preverify_ok == 1)
699 {
700 tls_out.dane_verified = tls_out.certificate_verified = TRUE;
701 #ifndef DISABLE_OCSP
702 if (client_static_cbinfo->u_ocsp.client.verify_store)
703 { /* client, wanting stapling */
704 /* Add the server cert's signing chain as the one
705 for the verification of the OCSP stapled information. */
706
707 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
708 cert))
709 ERR_clear_error();
710 sk_X509_push(client_static_cbinfo->verify_stack, cert);
711 }
712 #endif
713 }
714 else
715 {
716 int err = X509_STORE_CTX_get_error(x509ctx);
717 DEBUG(D_tls)
718 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
719 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
720 preverify_ok = 1;
721 }
722 return preverify_ok;
723 }
724
725 #endif /*SUPPORT_DANE*/
726
727
728 /*************************************************
729 * Information callback *
730 *************************************************/
731
732 /* The SSL library functions call this from time to time to indicate what they
733 are doing. We copy the string to the debugging output when TLS debugging has
734 been requested.
735
736 Arguments:
737 s the SSL connection
738 where
739 ret
740
741 Returns: nothing
742 */
743
744 static void
745 info_callback(SSL *s, int where, int ret)
746 {
747 DEBUG(D_tls)
748 {
749 const uschar * str;
750
751 if (where & SSL_ST_CONNECT)
752 str = "SSL_connect";
753 else if (where & SSL_ST_ACCEPT)
754 str = "SSL_accept";
755 else
756 str = "SSL info (undefined)";
757
758 if (where & SSL_CB_LOOP)
759 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
760 else if (where & SSL_CB_ALERT)
761 debug_printf("SSL3 alert %s:%s:%s\n",
762 str = where & SSL_CB_READ ? "read" : "write",
763 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
764 else if (where & SSL_CB_EXIT)
765 if (ret == 0)
766 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
767 else if (ret < 0)
768 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
769 else if (where & SSL_CB_HANDSHAKE_START)
770 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
771 else if (where & SSL_CB_HANDSHAKE_DONE)
772 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
773 }
774 }
775
776
777
778 /*************************************************
779 * Initialize for DH *
780 *************************************************/
781
782 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
783
784 Arguments:
785 sctx The current SSL CTX (inbound or outbound)
786 dhparam DH parameter file or fixed parameter identity string
787 host connected host, if client; NULL if server
788 errstr error string pointer
789
790 Returns: TRUE if OK (nothing to set up, or setup worked)
791 */
792
793 static BOOL
794 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
795 {
796 BIO *bio;
797 DH *dh;
798 uschar *dhexpanded;
799 const char *pem;
800 int dh_bitsize;
801
802 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
803 return FALSE;
804
805 if (!dhexpanded || !*dhexpanded)
806 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
807 else if (dhexpanded[0] == '/')
808 {
809 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
810 {
811 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
812 host, US strerror(errno), errstr);
813 return FALSE;
814 }
815 }
816 else
817 {
818 if (Ustrcmp(dhexpanded, "none") == 0)
819 {
820 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
821 return TRUE;
822 }
823
824 if (!(pem = std_dh_prime_named(dhexpanded)))
825 {
826 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
827 host, US strerror(errno), errstr);
828 return FALSE;
829 }
830 bio = BIO_new_mem_buf(CS pem, -1);
831 }
832
833 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
834 {
835 BIO_free(bio);
836 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
837 host, NULL, errstr);
838 return FALSE;
839 }
840
841 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
842 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
843 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
844 * If someone wants to dance at the edge, then they can raise the limit or use
845 * current libraries. */
846 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
847 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
848 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
849 dh_bitsize = DH_bits(dh);
850 #else
851 dh_bitsize = 8 * DH_size(dh);
852 #endif
853
854 /* Even if it is larger, we silently return success rather than cause things
855 * to fail out, so that a too-large DH will not knock out all TLS; it's a
856 * debatable choice. */
857 if (dh_bitsize > tls_dh_max_bits)
858 {
859 DEBUG(D_tls)
860 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
861 dh_bitsize, tls_dh_max_bits);
862 }
863 else
864 {
865 SSL_CTX_set_tmp_dh(sctx, dh);
866 DEBUG(D_tls)
867 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
868 dhexpanded ? dhexpanded : US"default", dh_bitsize);
869 }
870
871 DH_free(dh);
872 BIO_free(bio);
873
874 return TRUE;
875 }
876
877
878
879
880 /*************************************************
881 * Initialize for ECDH *
882 *************************************************/
883
884 /* Load parameters for ECDH encryption.
885
886 For now, we stick to NIST P-256 because: it's simple and easy to configure;
887 it avoids any patent issues that might bite redistributors; despite events in
888 the news and concerns over curve choices, we're not cryptographers, we're not
889 pretending to be, and this is "good enough" to be better than no support,
890 protecting against most adversaries. Given another year or two, there might
891 be sufficient clarity about a "right" way forward to let us make an informed
892 decision, instead of a knee-jerk reaction.
893
894 Longer-term, we should look at supporting both various named curves and
895 external files generated with "openssl ecparam", much as we do for init_dh().
896 We should also support "none" as a value, to explicitly avoid initialisation.
897
898 Patches welcome.
899
900 Arguments:
901 sctx The current SSL CTX (inbound or outbound)
902 host connected host, if client; NULL if server
903 errstr error string pointer
904
905 Returns: TRUE if OK (nothing to set up, or setup worked)
906 */
907
908 static BOOL
909 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
910 {
911 #ifdef OPENSSL_NO_ECDH
912 return TRUE;
913 #else
914
915 EC_KEY * ecdh;
916 uschar * exp_curve;
917 int nid;
918 BOOL rv;
919
920 if (host) /* No ECDH setup for clients, only for servers */
921 return TRUE;
922
923 # ifndef EXIM_HAVE_ECDH
924 DEBUG(D_tls)
925 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
926 return TRUE;
927 # else
928
929 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
930 return FALSE;
931 if (!exp_curve || !*exp_curve)
932 return TRUE;
933
934 /* "auto" needs to be handled carefully.
935 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
936 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
937 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
938 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
939 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
940 */
941 if (Ustrcmp(exp_curve, "auto") == 0)
942 {
943 #if OPENSSL_VERSION_NUMBER < 0x10002000L
944 DEBUG(D_tls) debug_printf(
945 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
946 exp_curve = US"prime256v1";
947 #else
948 # if defined SSL_CTRL_SET_ECDH_AUTO
949 DEBUG(D_tls) debug_printf(
950 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
951 SSL_CTX_set_ecdh_auto(sctx, 1);
952 return TRUE;
953 # else
954 DEBUG(D_tls) debug_printf(
955 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
956 return TRUE;
957 # endif
958 #endif
959 }
960
961 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
962 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
963 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
964 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
965 # endif
966 )
967 {
968 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
969 host, NULL, errstr);
970 return FALSE;
971 }
972
973 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
974 {
975 tls_error(US"Unable to create ec curve", host, NULL, errstr);
976 return FALSE;
977 }
978
979 /* The "tmp" in the name here refers to setting a temporary key
980 not to the stability of the interface. */
981
982 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
983 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
984 else
985 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
986
987 EC_KEY_free(ecdh);
988 return !rv;
989
990 # endif /*EXIM_HAVE_ECDH*/
991 #endif /*OPENSSL_NO_ECDH*/
992 }
993
994
995
996
997 #ifndef DISABLE_OCSP
998 /*************************************************
999 * Load OCSP information into state *
1000 *************************************************/
1001 /* Called to load the server OCSP response from the given file into memory, once
1002 caller has determined this is needed. Checks validity. Debugs a message
1003 if invalid.
1004
1005 ASSUMES: single response, for single cert.
1006
1007 Arguments:
1008 sctx the SSL_CTX* to update
1009 cbinfo various parts of session state
1010 expanded the filename putatively holding an OCSP response
1011
1012 */
1013
1014 static void
1015 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
1016 {
1017 BIO * bio;
1018 OCSP_RESPONSE * resp;
1019 OCSP_BASICRESP * basic_response;
1020 OCSP_SINGLERESP * single_response;
1021 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1022 STACK_OF(X509) * sk;
1023 unsigned long verify_flags;
1024 int status, reason, i;
1025
1026 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
1027 if (cbinfo->u_ocsp.server.response)
1028 {
1029 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
1030 cbinfo->u_ocsp.server.response = NULL;
1031 }
1032
1033 if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
1034 {
1035 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
1036 cbinfo->u_ocsp.server.file_expanded);
1037 return;
1038 }
1039
1040 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1041 BIO_free(bio);
1042 if (!resp)
1043 {
1044 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
1045 return;
1046 }
1047
1048 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1049 {
1050 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1051 OCSP_response_status_str(status), status);
1052 goto bad;
1053 }
1054
1055 if (!(basic_response = OCSP_response_get1_basic(resp)))
1056 {
1057 DEBUG(D_tls)
1058 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1059 goto bad;
1060 }
1061
1062 sk = cbinfo->verify_stack;
1063 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1064
1065 /* May need to expose ability to adjust those flags?
1066 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1067 OCSP_TRUSTOTHER OCSP_NOINTERN */
1068
1069 /* This does a full verify on the OCSP proof before we load it for serving
1070 up; possibly overkill - just date-checks might be nice enough.
1071
1072 OCSP_basic_verify takes a "store" arg, but does not
1073 use it for the chain verification, which is all we do
1074 when OCSP_NOVERIFY is set. The content from the wire
1075 "basic_response" and a cert-stack "sk" are all that is used.
1076
1077 We have a stack, loaded in setup_certs() if tls_verify_certificates
1078 was a file (not a directory, or "system"). It is unfortunate we
1079 cannot used the connection context store, as that would neatly
1080 handle the "system" case too, but there seems to be no library
1081 function for getting a stack from a store.
1082 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1083 We do not free the stack since it could be needed a second time for
1084 SNI handling.
1085
1086 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1087 be a public interface into the OpenSSL library (there's no manual entry) -
1088 But what with? We also use OCSP_basic_verify in the client stapling callback.
1089 And there we NEED it; we must verify that status... unless the
1090 library does it for us anyway? */
1091
1092 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1093 {
1094 DEBUG(D_tls)
1095 {
1096 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1097 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1098 }
1099 goto bad;
1100 }
1101
1102 /* Here's the simplifying assumption: there's only one response, for the
1103 one certificate we use, and nothing for anything else in a chain. If this
1104 proves false, we need to extract a cert id from our issued cert
1105 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1106 right cert in the stack and then calls OCSP_single_get0_status()).
1107
1108 I'm hoping to avoid reworking a bunch more of how we handle state here. */
1109
1110 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1111 {
1112 DEBUG(D_tls)
1113 debug_printf("Unable to get first response from OCSP basic response.\n");
1114 goto bad;
1115 }
1116
1117 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1118 if (status != V_OCSP_CERTSTATUS_GOOD)
1119 {
1120 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1121 OCSP_cert_status_str(status), status,
1122 OCSP_crl_reason_str(reason), reason);
1123 goto bad;
1124 }
1125
1126 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1127 {
1128 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1129 goto bad;
1130 }
1131
1132 supply_response:
1133 cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/
1134 return;
1135
1136 bad:
1137 if (f.running_in_test_harness)
1138 {
1139 extern char ** environ;
1140 uschar ** p;
1141 if (environ) for (p = USS environ; *p; p++)
1142 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1143 {
1144 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1145 goto supply_response;
1146 }
1147 }
1148 return;
1149 }
1150 #endif /*!DISABLE_OCSP*/
1151
1152
1153
1154
1155 /* Create and install a selfsigned certificate, for use in server mode */
1156
1157 static int
1158 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
1159 {
1160 X509 * x509 = NULL;
1161 EVP_PKEY * pkey;
1162 RSA * rsa;
1163 X509_NAME * name;
1164 uschar * where;
1165
1166 where = US"allocating pkey";
1167 if (!(pkey = EVP_PKEY_new()))
1168 goto err;
1169
1170 where = US"allocating cert";
1171 if (!(x509 = X509_new()))
1172 goto err;
1173
1174 where = US"generating pkey";
1175 if (!(rsa = rsa_callback(NULL, 0, 1024)))
1176 goto err;
1177
1178 where = US"assigning pkey";
1179 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1180 goto err;
1181
1182 X509_set_version(x509, 2); /* N+1 - version 3 */
1183 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1184 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1185 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1186 X509_set_pubkey(x509, pkey);
1187
1188 name = X509_get_subject_name(x509);
1189 X509_NAME_add_entry_by_txt(name, "C",
1190 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1191 X509_NAME_add_entry_by_txt(name, "O",
1192 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1193 X509_NAME_add_entry_by_txt(name, "CN",
1194 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1195 X509_set_issuer_name(x509, name);
1196
1197 where = US"signing cert";
1198 if (!X509_sign(x509, pkey, EVP_md5()))
1199 goto err;
1200
1201 where = US"installing selfsign cert";
1202 if (!SSL_CTX_use_certificate(sctx, x509))
1203 goto err;
1204
1205 where = US"installing selfsign key";
1206 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1207 goto err;
1208
1209 return OK;
1210
1211 err:
1212 (void) tls_error(where, NULL, NULL, errstr);
1213 if (x509) X509_free(x509);
1214 if (pkey) EVP_PKEY_free(pkey);
1215 return DEFER;
1216 }
1217
1218
1219
1220
1221 static int
1222 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1223 uschar ** errstr)
1224 {
1225 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file);
1226 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1227 return tls_error(string_sprintf(
1228 "SSL_CTX_use_certificate_chain_file file=%s", file),
1229 cbinfo->host, NULL, errstr);
1230 return 0;
1231 }
1232
1233 static int
1234 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1235 uschar ** errstr)
1236 {
1237 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file);
1238 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1239 return tls_error(string_sprintf(
1240 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1241 return 0;
1242 }
1243
1244
1245 /*************************************************
1246 * Expand key and cert file specs *
1247 *************************************************/
1248
1249 /* Called once during tls_init and possibly again during TLS setup, for a
1250 new context, if Server Name Indication was used and tls_sni was seen in
1251 the certificate string.
1252
1253 Arguments:
1254 sctx the SSL_CTX* to update
1255 cbinfo various parts of session state
1256 errstr error string pointer
1257
1258 Returns: OK/DEFER/FAIL
1259 */
1260
1261 static int
1262 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1263 uschar ** errstr)
1264 {
1265 uschar *expanded;
1266
1267 if (!cbinfo->certificate)
1268 {
1269 if (!cbinfo->is_server) /* client */
1270 return OK;
1271 /* server */
1272 if (tls_install_selfsign(sctx, errstr) != OK)
1273 return DEFER;
1274 }
1275 else
1276 {
1277 int err;
1278
1279 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1280 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1281 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1282 )
1283 reexpand_tls_files_for_sni = TRUE;
1284
1285 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1286 return DEFER;
1287
1288 if (expanded)
1289 if (cbinfo->is_server)
1290 {
1291 const uschar * file_list = expanded;
1292 int sep = 0;
1293 uschar * file;
1294
1295 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1296 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1297 return err;
1298 }
1299 else /* would there ever be a need for multiple client certs? */
1300 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1301 return err;
1302
1303 if (cbinfo->privatekey != NULL &&
1304 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1305 return DEFER;
1306
1307 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1308 of the expansion is an empty string, ignore it also, and assume the private
1309 key is in the same file as the certificate. */
1310
1311 if (expanded && *expanded)
1312 if (cbinfo->is_server)
1313 {
1314 const uschar * file_list = expanded;
1315 int sep = 0;
1316 uschar * file;
1317
1318 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1319 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1320 return err;
1321 }
1322 else /* would there ever be a need for multiple client certs? */
1323 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1324 return err;
1325 }
1326
1327 #ifndef DISABLE_OCSP
1328 if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
1329 {
1330 /*XXX stack*/
1331 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
1332 return DEFER;
1333
1334 if (expanded && *expanded)
1335 {
1336 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
1337 if ( cbinfo->u_ocsp.server.file_expanded
1338 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
1339 {
1340 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1341 }
1342 else
1343 ocsp_load_response(sctx, cbinfo, expanded);
1344 }
1345 }
1346 #endif
1347
1348 return OK;
1349 }
1350
1351
1352
1353
1354 /*************************************************
1355 * Callback to handle SNI *
1356 *************************************************/
1357
1358 /* Called when acting as server during the TLS session setup if a Server Name
1359 Indication extension was sent by the client.
1360
1361 API documentation is OpenSSL s_server.c implementation.
1362
1363 Arguments:
1364 s SSL* of the current session
1365 ad unknown (part of OpenSSL API) (unused)
1366 arg Callback of "our" registered data
1367
1368 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1369 */
1370
1371 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1372 static int
1373 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1374 {
1375 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1376 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1377 int rc;
1378 int old_pool = store_pool;
1379 uschar * dummy_errstr;
1380
1381 if (!servername)
1382 return SSL_TLSEXT_ERR_OK;
1383
1384 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1385 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1386
1387 /* Make the extension value available for expansion */
1388 store_pool = POOL_PERM;
1389 tls_in.sni = string_copy(US servername);
1390 store_pool = old_pool;
1391
1392 if (!reexpand_tls_files_for_sni)
1393 return SSL_TLSEXT_ERR_OK;
1394
1395 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1396 not confident that memcpy wouldn't break some internal reference counting.
1397 Especially since there's a references struct member, which would be off. */
1398
1399 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1400 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1401 #else
1402 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1403 #endif
1404 {
1405 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1406 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1407 return SSL_TLSEXT_ERR_NOACK;
1408 }
1409
1410 /* Not sure how many of these are actually needed, since SSL object
1411 already exists. Might even need this selfsame callback, for reneg? */
1412
1413 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1414 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1415 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1416 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1417 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1418 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1419
1420 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1421 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1422 )
1423 return SSL_TLSEXT_ERR_NOACK;
1424
1425 if ( cbinfo->server_cipher_list
1426 && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list))
1427 return SSL_TLSEXT_ERR_NOACK;
1428
1429 #ifndef DISABLE_OCSP
1430 if (cbinfo->u_ocsp.server.file)
1431 {
1432 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1433 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1434 }
1435 #endif
1436
1437 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1438 verify_callback_server, &dummy_errstr)) != OK)
1439 return SSL_TLSEXT_ERR_NOACK;
1440
1441 /* do this after setup_certs, because this can require the certs for verifying
1442 OCSP information. */
1443 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1444 return SSL_TLSEXT_ERR_NOACK;
1445
1446 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1447 SSL_set_SSL_CTX(s, server_sni);
1448
1449 return SSL_TLSEXT_ERR_OK;
1450 }
1451 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1452
1453
1454
1455
1456 #ifndef DISABLE_OCSP
1457
1458 /*************************************************
1459 * Callback to handle OCSP Stapling *
1460 *************************************************/
1461
1462 /* Called when acting as server during the TLS session setup if the client
1463 requests OCSP information with a Certificate Status Request.
1464
1465 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1466 project.
1467
1468 */
1469
1470 static int
1471 tls_server_stapling_cb(SSL *s, void *arg)
1472 {
1473 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1474 uschar *response_der; /*XXX blob */
1475 int response_der_len;
1476
1477 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1478 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1479 buggy in current OpenSSL; it returns the last cert loaded always rather than
1480 the one actually presented. So we can't support a stack of OCSP proofs at
1481 this time. */
1482
1483 DEBUG(D_tls)
1484 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1485 cbinfo->u_ocsp.server.response ? "have" : "lack");
1486
1487 tls_in.ocsp = OCSP_NOT_RESP;
1488 if (!cbinfo->u_ocsp.server.response)
1489 return SSL_TLSEXT_ERR_NOACK;
1490
1491 response_der = NULL;
1492 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1493 &response_der);
1494 if (response_der_len <= 0)
1495 return SSL_TLSEXT_ERR_NOACK;
1496
1497 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1498 tls_in.ocsp = OCSP_VFIED;
1499 return SSL_TLSEXT_ERR_OK;
1500 }
1501
1502
1503 static void
1504 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1505 {
1506 BIO_printf(bp, "\t%s: ", str);
1507 ASN1_GENERALIZEDTIME_print(bp, time);
1508 BIO_puts(bp, "\n");
1509 }
1510
1511 static int
1512 tls_client_stapling_cb(SSL *s, void *arg)
1513 {
1514 tls_ext_ctx_cb * cbinfo = arg;
1515 const unsigned char * p;
1516 int len;
1517 OCSP_RESPONSE * rsp;
1518 OCSP_BASICRESP * bs;
1519 int i;
1520
1521 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1522 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1523 if(!p)
1524 {
1525 /* Expect this when we requested ocsp but got none */
1526 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1527 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1528 else
1529 DEBUG(D_tls) debug_printf(" null\n");
1530 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1531 }
1532
1533 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1534 {
1535 tls_out.ocsp = OCSP_FAILED;
1536 if (LOGGING(tls_cipher))
1537 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1538 else
1539 DEBUG(D_tls) debug_printf(" parse error\n");
1540 return 0;
1541 }
1542
1543 if(!(bs = OCSP_response_get1_basic(rsp)))
1544 {
1545 tls_out.ocsp = OCSP_FAILED;
1546 if (LOGGING(tls_cipher))
1547 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1548 else
1549 DEBUG(D_tls) debug_printf(" error parsing response\n");
1550 OCSP_RESPONSE_free(rsp);
1551 return 0;
1552 }
1553
1554 /* We'd check the nonce here if we'd put one in the request. */
1555 /* However that would defeat cacheability on the server so we don't. */
1556
1557 /* This section of code reworked from OpenSSL apps source;
1558 The OpenSSL Project retains copyright:
1559 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1560 */
1561 {
1562 BIO * bp = NULL;
1563 int status, reason;
1564 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1565
1566 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1567
1568 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1569
1570 /* Use the chain that verified the server cert to verify the stapled info */
1571 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1572
1573 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1574 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1575 {
1576 tls_out.ocsp = OCSP_FAILED;
1577 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1578 "Received TLS cert status response, itself unverifiable: %s",
1579 ERR_reason_error_string(ERR_peek_error()));
1580 BIO_printf(bp, "OCSP response verify failure\n");
1581 ERR_print_errors(bp);
1582 OCSP_RESPONSE_print(bp, rsp, 0);
1583 goto failed;
1584 }
1585
1586 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1587
1588 /*XXX So we have a good stapled OCSP status. How do we know
1589 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1590 OCSP_resp_find_status() which matches on a cert id, which presumably
1591 we should use. Making an id needs OCSP_cert_id_new(), which takes
1592 issuerName, issuerKey, serialNumber. Are they all in the cert?
1593
1594 For now, carry on blindly accepting the resp. */
1595
1596 {
1597 OCSP_SINGLERESP * single;
1598
1599 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1600 if (OCSP_resp_count(bs) != 1)
1601 #else
1602 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1603 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1604 #endif
1605 {
1606 tls_out.ocsp = OCSP_FAILED;
1607 log_write(0, LOG_MAIN, "OCSP stapling "
1608 "with multiple responses not handled");
1609 goto failed;
1610 }
1611 single = OCSP_resp_get0(bs, 0);
1612 status = OCSP_single_get0_status(single, &reason, &rev,
1613 &thisupd, &nextupd);
1614 }
1615
1616 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1617 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1618 if (!OCSP_check_validity(thisupd, nextupd,
1619 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1620 {
1621 tls_out.ocsp = OCSP_FAILED;
1622 DEBUG(D_tls) ERR_print_errors(bp);
1623 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1624 }
1625 else
1626 {
1627 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1628 OCSP_cert_status_str(status));
1629 switch(status)
1630 {
1631 case V_OCSP_CERTSTATUS_GOOD:
1632 tls_out.ocsp = OCSP_VFIED;
1633 i = 1;
1634 goto good;
1635 case V_OCSP_CERTSTATUS_REVOKED:
1636 tls_out.ocsp = OCSP_FAILED;
1637 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1638 reason != -1 ? "; reason: " : "",
1639 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1640 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1641 break;
1642 default:
1643 tls_out.ocsp = OCSP_FAILED;
1644 log_write(0, LOG_MAIN,
1645 "Server certificate status unknown, in OCSP stapling");
1646 break;
1647 }
1648 }
1649 failed:
1650 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1651 good:
1652 BIO_free(bp);
1653 }
1654
1655 OCSP_RESPONSE_free(rsp);
1656 return i;
1657 }
1658 #endif /*!DISABLE_OCSP*/
1659
1660
1661 /*************************************************
1662 * Initialize for TLS *
1663 *************************************************/
1664
1665 /* Called from both server and client code, to do preliminary initialization
1666 of the library. We allocate and return a context structure.
1667
1668 Arguments:
1669 ctxp returned SSL context
1670 host connected host, if client; NULL if server
1671 dhparam DH parameter file
1672 certificate certificate file
1673 privatekey private key
1674 ocsp_file file of stapling info (server); flag for require ocsp (client)
1675 addr address if client; NULL if server (for some randomness)
1676 cbp place to put allocated callback context
1677 errstr error string pointer
1678
1679 Returns: OK/DEFER/FAIL
1680 */
1681
1682 static int
1683 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1684 uschar *privatekey,
1685 #ifndef DISABLE_OCSP
1686 uschar *ocsp_file, /*XXX stack, in server*/
1687 #endif
1688 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
1689 {
1690 SSL_CTX * ctx;
1691 long init_options;
1692 int rc;
1693 tls_ext_ctx_cb * cbinfo;
1694
1695 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1696 cbinfo->certificate = certificate;
1697 cbinfo->privatekey = privatekey;
1698 cbinfo->is_server = host==NULL;
1699 #ifndef DISABLE_OCSP
1700 cbinfo->verify_stack = NULL;
1701 if (!host)
1702 {
1703 cbinfo->u_ocsp.server.file = ocsp_file;
1704 cbinfo->u_ocsp.server.file_expanded = NULL;
1705 cbinfo->u_ocsp.server.response = NULL;
1706 }
1707 else
1708 cbinfo->u_ocsp.client.verify_store = NULL;
1709 #endif
1710 cbinfo->dhparam = dhparam;
1711 cbinfo->server_cipher_list = NULL;
1712 cbinfo->host = host;
1713 #ifndef DISABLE_EVENT
1714 cbinfo->event_action = NULL;
1715 #endif
1716
1717 SSL_load_error_strings(); /* basic set up */
1718 OpenSSL_add_ssl_algorithms();
1719
1720 #ifdef EXIM_HAVE_SHA256
1721 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1722 list of available digests. */
1723 EVP_add_digest(EVP_sha256());
1724 #endif
1725
1726 /* Create a context.
1727 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1728 negotiation in the different methods; as far as I can tell, the only
1729 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1730 when OpenSSL is built without SSLv2 support.
1731 By disabling with openssl_options, we can let admins re-enable with the
1732 existing knob. */
1733
1734 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1735 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1736 #else
1737 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1738 #endif
1739 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1740
1741 /* It turns out that we need to seed the random number generator this early in
1742 order to get the full complement of ciphers to work. It took me roughly a day
1743 of work to discover this by experiment.
1744
1745 On systems that have /dev/urandom, SSL may automatically seed itself from
1746 there. Otherwise, we have to make something up as best we can. Double check
1747 afterwards. */
1748
1749 if (!RAND_status())
1750 {
1751 randstuff r;
1752 gettimeofday(&r.tv, NULL);
1753 r.p = getpid();
1754
1755 RAND_seed(US (&r), sizeof(r));
1756 RAND_seed(US big_buffer, big_buffer_size);
1757 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1758
1759 if (!RAND_status())
1760 return tls_error(US"RAND_status", host,
1761 US"unable to seed random number generator", errstr);
1762 }
1763
1764 /* Set up the information callback, which outputs if debugging is at a suitable
1765 level. */
1766
1767 DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1768
1769 /* Automatically re-try reads/writes after renegotiation. */
1770 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1771
1772 /* Apply administrator-supplied work-arounds.
1773 Historically we applied just one requested option,
1774 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1775 moved to an administrator-controlled list of options to specify and
1776 grandfathered in the first one as the default value for "openssl_options".
1777
1778 No OpenSSL version number checks: the options we accept depend upon the
1779 availability of the option value macros from OpenSSL. */
1780
1781 if (!tls_openssl_options_parse(openssl_options, &init_options))
1782 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1783
1784 if (init_options)
1785 {
1786 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1787 if (!(SSL_CTX_set_options(ctx, init_options)))
1788 return tls_error(string_sprintf(
1789 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
1790 }
1791 else
1792 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1793
1794 /* We'd like to disable session cache unconditionally, but foolish Outlook
1795 Express clients then give up the first TLS connection and make a second one
1796 (which works). Only when there is an IMAP service on the same machine.
1797 Presumably OE is trying to use the cache for A on B. Leave it enabled for
1798 now, until we work out a decent way of presenting control to the config. It
1799 will never be used because we use a new context every time. */
1800 #ifdef notdef
1801 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
1802 #endif
1803
1804 /* Initialize with DH parameters if supplied */
1805 /* Initialize ECDH temp key parameter selection */
1806
1807 if ( !init_dh(ctx, dhparam, host, errstr)
1808 || !init_ecdh(ctx, host, errstr)
1809 )
1810 return DEFER;
1811
1812 /* Set up certificate and key (and perhaps OCSP info) */
1813
1814 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
1815 return rc;
1816
1817 /* If we need to handle SNI or OCSP, do so */
1818
1819 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1820 # ifndef DISABLE_OCSP
1821 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1822 {
1823 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1824 return FAIL;
1825 }
1826 # endif
1827
1828 if (!host) /* server */
1829 {
1830 # ifndef DISABLE_OCSP
1831 /* We check u_ocsp.server.file, not server.response, because we care about if
1832 the option exists, not what the current expansion might be, as SNI might
1833 change the certificate and OCSP file in use between now and the time the
1834 callback is invoked. */
1835 if (cbinfo->u_ocsp.server.file)
1836 {
1837 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
1838 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1839 }
1840 # endif
1841 /* We always do this, so that $tls_sni is available even if not used in
1842 tls_certificate */
1843 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
1844 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
1845 }
1846 # ifndef DISABLE_OCSP
1847 else /* client */
1848 if(ocsp_file) /* wanting stapling */
1849 {
1850 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1851 {
1852 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1853 return FAIL;
1854 }
1855 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
1856 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
1857 }
1858 # endif
1859 #endif
1860
1861 cbinfo->verify_cert_hostnames = NULL;
1862
1863 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1864 /* Set up the RSA callback */
1865 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
1866 #endif
1867
1868 /* Finally, set the timeout, and we are done */
1869
1870 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
1871 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1872
1873 *cbp = cbinfo;
1874 *ctxp = ctx;
1875
1876 return OK;
1877 }
1878
1879
1880
1881
1882 /*************************************************
1883 * Get name of cipher in use *
1884 *************************************************/
1885
1886 /*
1887 Argument: pointer to an SSL structure for the connection
1888 buffer to use for answer
1889 size of buffer
1890 pointer to number of bits for cipher
1891 Returns: nothing
1892 */
1893
1894 static void
1895 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1896 {
1897 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
1898 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1899 the accessor functions use const in the prototype. */
1900
1901 const uschar * ver = CUS SSL_get_version(ssl);
1902 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1903
1904 SSL_CIPHER_get_bits(c, bits);
1905
1906 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1907 SSL_CIPHER_get_name(c), *bits);
1908
1909 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1910 }
1911
1912
1913 static void
1914 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
1915 {
1916 /*XXX we might consider a list-of-certs variable for the cert chain.
1917 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1918 in list-handling functions, also consider the difference between the entire
1919 chain and the elements sent by the peer. */
1920
1921 tlsp->peerdn = NULL;
1922
1923 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1924 if (!tlsp->peercert)
1925 tlsp->peercert = SSL_get_peer_certificate(ssl);
1926 /* Beware anonymous ciphers which lead to server_cert being NULL */
1927 if (tlsp->peercert)
1928 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
1929 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
1930 else
1931 {
1932 peerdn[siz-1] = '\0';
1933 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1934 }
1935 }
1936
1937
1938
1939
1940
1941 /*************************************************
1942 * Set up for verifying certificates *
1943 *************************************************/
1944
1945 #ifndef DISABLE_OCSP
1946 /* Load certs from file, return TRUE on success */
1947
1948 static BOOL
1949 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1950 {
1951 BIO * bp;
1952 X509 * x;
1953
1954 while (sk_X509_num(verify_stack) > 0)
1955 X509_free(sk_X509_pop(verify_stack));
1956
1957 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1958 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1959 sk_X509_push(verify_stack, x);
1960 BIO_free(bp);
1961 return TRUE;
1962 }
1963 #endif
1964
1965
1966
1967 /* Called by both client and server startup; on the server possibly
1968 repeated after a Server Name Indication.
1969
1970 Arguments:
1971 sctx SSL_CTX* to initialise
1972 certs certs file or NULL
1973 crl CRL file or NULL
1974 host NULL in a server; the remote host in a client
1975 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1976 otherwise passed as FALSE
1977 cert_vfy_cb Callback function for certificate verification
1978 errstr error string pointer
1979
1980 Returns: OK/DEFER/FAIL
1981 */
1982
1983 static int
1984 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1985 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
1986 {
1987 uschar *expcerts, *expcrl;
1988
1989 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
1990 return DEFER;
1991 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
1992
1993 if (expcerts && *expcerts)
1994 {
1995 /* Tell the library to use its compiled-in location for the system default
1996 CA bundle. Then add the ones specified in the config, if any. */
1997
1998 if (!SSL_CTX_set_default_verify_paths(sctx))
1999 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2000
2001 if (Ustrcmp(expcerts, "system") != 0)
2002 {
2003 struct stat statbuf;
2004
2005 if (Ustat(expcerts, &statbuf) < 0)
2006 {
2007 log_write(0, LOG_MAIN|LOG_PANIC,
2008 "failed to stat %s for certificates", expcerts);
2009 return DEFER;
2010 }
2011 else
2012 {
2013 uschar *file, *dir;
2014 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2015 { file = NULL; dir = expcerts; }
2016 else
2017 {
2018 file = expcerts; dir = NULL;
2019 #ifndef DISABLE_OCSP
2020 /* In the server if we will be offering an OCSP proof, load chain from
2021 file for verifying the OCSP proof at load time. */
2022
2023 if ( !host
2024 && statbuf.st_size > 0
2025 && server_static_cbinfo->u_ocsp.server.file
2026 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
2027 )
2028 {
2029 log_write(0, LOG_MAIN|LOG_PANIC,
2030 "failed to load cert chain from %s", file);
2031 return DEFER;
2032 }
2033 #endif
2034 }
2035
2036 /* If a certificate file is empty, the next function fails with an
2037 unhelpful error message. If we skip it, we get the correct behaviour (no
2038 certificates are recognized, but the error message is still misleading (it
2039 says no certificate was supplied). But this is better. */
2040
2041 if ( (!file || statbuf.st_size > 0)
2042 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2043 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
2044
2045 /* Load the list of CAs for which we will accept certs, for sending
2046 to the client. This is only for the one-file tls_verify_certificates
2047 variant.
2048 If a list isn't loaded into the server, but
2049 some verify locations are set, the server end appears to make
2050 a wildcard request for client certs.
2051 Meanwhile, the client library as default behaviour *ignores* the list
2052 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2053 Because of this, and that the dir variant is likely only used for
2054 the public-CA bundle (not for a private CA), not worth fixing.
2055 */
2056 if (file)
2057 {
2058 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2059
2060 SSL_CTX_set_client_CA_list(sctx, names);
2061 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
2062 sk_X509_NAME_num(names));
2063 }
2064 }
2065 }
2066
2067 /* Handle a certificate revocation list. */
2068
2069 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2070
2071 /* This bit of code is now the version supplied by Lars Mainka. (I have
2072 merely reformatted it into the Exim code style.)
2073
2074 "From here I changed the code to add support for multiple crl's
2075 in pem format in one file or to support hashed directory entries in
2076 pem format instead of a file. This method now uses the library function
2077 X509_STORE_load_locations to add the CRL location to the SSL context.
2078 OpenSSL will then handle the verify against CA certs and CRLs by
2079 itself in the verify callback." */
2080
2081 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2082 if (expcrl && *expcrl)
2083 {
2084 struct stat statbufcrl;
2085 if (Ustat(expcrl, &statbufcrl) < 0)
2086 {
2087 log_write(0, LOG_MAIN|LOG_PANIC,
2088 "failed to stat %s for certificates revocation lists", expcrl);
2089 return DEFER;
2090 }
2091 else
2092 {
2093 /* is it a file or directory? */
2094 uschar *file, *dir;
2095 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2096 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2097 {
2098 file = NULL;
2099 dir = expcrl;
2100 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2101 }
2102 else
2103 {
2104 file = expcrl;
2105 dir = NULL;
2106 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2107 }
2108 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2109 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2110
2111 /* setting the flags to check against the complete crl chain */
2112
2113 X509_STORE_set_flags(cvstore,
2114 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2115 }
2116 }
2117
2118 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2119
2120 /* If verification is optional, don't fail if no certificate */
2121
2122 SSL_CTX_set_verify(sctx,
2123 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2124 cert_vfy_cb);
2125 }
2126
2127 return OK;
2128 }
2129
2130
2131
2132 /*************************************************
2133 * Start a TLS session in a server *
2134 *************************************************/
2135
2136 /* This is called when Exim is running as a server, after having received
2137 the STARTTLS command. It must respond to that command, and then negotiate
2138 a TLS session.
2139
2140 Arguments:
2141 require_ciphers allowed ciphers
2142 errstr pointer to error message
2143
2144 Returns: OK on success
2145 DEFER for errors before the start of the negotiation
2146 FAIL for errors during the negotiation; the server can't
2147 continue running.
2148 */
2149
2150 int
2151 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2152 {
2153 int rc;
2154 uschar * expciphers;
2155 tls_ext_ctx_cb * cbinfo;
2156 static uschar peerdn[256];
2157 static uschar cipherbuf[256];
2158
2159 /* Check for previous activation */
2160
2161 if (tls_in.active.sock >= 0)
2162 {
2163 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2164 smtp_printf("554 Already in TLS\r\n", FALSE);
2165 return FAIL;
2166 }
2167
2168 /* Initialize the SSL library. If it fails, it will already have logged
2169 the error. */
2170
2171 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
2172 #ifndef DISABLE_OCSP
2173 tls_ocsp_file, /*XXX stack*/
2174 #endif
2175 NULL, &server_static_cbinfo, errstr);
2176 if (rc != OK) return rc;
2177 cbinfo = server_static_cbinfo;
2178
2179 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2180 return FAIL;
2181
2182 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2183 were historically separated by underscores. So that I can use either form in my
2184 tests, and also for general convenience, we turn underscores into hyphens here.
2185
2186 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2187 for TLS 1.3 . Since we do not call it at present we get the default list:
2188 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2189 */
2190
2191 if (expciphers)
2192 {
2193 uschar * s = expciphers;
2194 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2195 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2196 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2197 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2198 cbinfo->server_cipher_list = expciphers;
2199 }
2200
2201 /* If this is a host for which certificate verification is mandatory or
2202 optional, set up appropriately. */
2203
2204 tls_in.certificate_verified = FALSE;
2205 #ifdef SUPPORT_DANE
2206 tls_in.dane_verified = FALSE;
2207 #endif
2208 server_verify_callback_called = FALSE;
2209
2210 if (verify_check_host(&tls_verify_hosts) == OK)
2211 {
2212 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2213 FALSE, verify_callback_server, errstr);
2214 if (rc != OK) return rc;
2215 server_verify_optional = FALSE;
2216 }
2217 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2218 {
2219 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2220 TRUE, verify_callback_server, errstr);
2221 if (rc != OK) return rc;
2222 server_verify_optional = TRUE;
2223 }
2224
2225 /* Prepare for new connection */
2226
2227 if (!(server_ssl = SSL_new(server_ctx)))
2228 return tls_error(US"SSL_new", NULL, NULL, errstr);
2229
2230 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2231 *
2232 * With the SSL_clear(), we get strange interoperability bugs with
2233 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2234 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2235 *
2236 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2237 * session shutdown. In this case, we have a brand new object and there's no
2238 * obvious reason to immediately clear it. I'm guessing that this was
2239 * originally added because of incomplete initialisation which the clear fixed,
2240 * in some historic release.
2241 */
2242
2243 /* Set context and tell client to go ahead, except in the case of TLS startup
2244 on connection, where outputting anything now upsets the clients and tends to
2245 make them disconnect. We need to have an explicit fflush() here, to force out
2246 the response. Other smtp_printf() calls do not need it, because in non-TLS
2247 mode, the fflush() happens when smtp_getc() is called. */
2248
2249 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2250 if (!tls_in.on_connect)
2251 {
2252 smtp_printf("220 TLS go ahead\r\n", FALSE);
2253 fflush(smtp_out);
2254 }
2255
2256 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2257 that the OpenSSL library doesn't. */
2258
2259 SSL_set_wfd(server_ssl, fileno(smtp_out));
2260 SSL_set_rfd(server_ssl, fileno(smtp_in));
2261 SSL_set_accept_state(server_ssl);
2262
2263 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2264
2265 sigalrm_seen = FALSE;
2266 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2267 rc = SSL_accept(server_ssl);
2268 alarm(0);
2269
2270 if (rc <= 0)
2271 {
2272 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2273 return FAIL;
2274 }
2275
2276 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2277
2278 /* TLS has been set up. Adjust the input functions to read via TLS,
2279 and initialize things. */
2280
2281 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2282
2283 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
2284 tls_in.cipher = cipherbuf;
2285
2286 DEBUG(D_tls)
2287 {
2288 uschar buf[2048];
2289 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
2290 debug_printf("Shared ciphers: %s\n", buf);
2291 }
2292
2293 /* Record the certificate we presented */
2294 {
2295 X509 * crt = SSL_get_certificate(server_ssl);
2296 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2297 }
2298
2299 /* Only used by the server-side tls (tls_in), including tls_getc.
2300 Client-side (tls_out) reads (seem to?) go via
2301 smtp_read_response()/ip_recv().
2302 Hence no need to duplicate for _in and _out.
2303 */
2304 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2305 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2306 ssl_xfer_eof = ssl_xfer_error = FALSE;
2307
2308 receive_getc = tls_getc;
2309 receive_getbuf = tls_getbuf;
2310 receive_get_cache = tls_get_cache;
2311 receive_ungetc = tls_ungetc;
2312 receive_feof = tls_feof;
2313 receive_ferror = tls_ferror;
2314 receive_smtp_buffered = tls_smtp_buffered;
2315
2316 tls_in.active.sock = fileno(smtp_out);
2317 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2318 return OK;
2319 }
2320
2321
2322
2323
2324 static int
2325 tls_client_basic_ctx_init(SSL_CTX * ctx,
2326 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2327 uschar ** errstr)
2328 {
2329 int rc;
2330 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2331 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2332 the specified host patterns if one of them is defined */
2333
2334 if ( ( !ob->tls_verify_hosts
2335 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2336 )
2337 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2338 )
2339 client_verify_optional = FALSE;
2340 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2341 client_verify_optional = TRUE;
2342 else
2343 return OK;
2344
2345 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2346 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2347 errstr)) != OK)
2348 return rc;
2349
2350 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2351 {
2352 cbinfo->verify_cert_hostnames =
2353 #ifdef SUPPORT_I18N
2354 string_domain_utf8_to_alabel(host->name, NULL);
2355 #else
2356 host->name;
2357 #endif
2358 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2359 cbinfo->verify_cert_hostnames);
2360 }
2361 return OK;
2362 }
2363
2364
2365 #ifdef SUPPORT_DANE
2366 static int
2367 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2368 {
2369 dns_record * rr;
2370 dns_scan dnss;
2371 const char * hostnames[2] = { CS host->name, NULL };
2372 int found = 0;
2373
2374 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2375 return tls_error(US"hostnames load", host, NULL, errstr);
2376
2377 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2378 rr;
2379 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2380 ) if (rr->type == T_TLSA && rr->size > 3)
2381 {
2382 const uschar * p = rr->data;
2383 uint8_t usage, selector, mtype;
2384 const char * mdname;
2385
2386 usage = *p++;
2387
2388 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2389 if (usage != 2 && usage != 3) continue;
2390
2391 selector = *p++;
2392 mtype = *p++;
2393
2394 switch (mtype)
2395 {
2396 default: continue; /* Only match-types 0, 1, 2 are supported */
2397 case 0: mdname = NULL; break;
2398 case 1: mdname = "sha256"; break;
2399 case 2: mdname = "sha512"; break;
2400 }
2401
2402 found++;
2403 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2404 {
2405 default:
2406 return tls_error(US"tlsa load", host, NULL, errstr);
2407 case 0: /* action not taken */
2408 case 1: break;
2409 }
2410
2411 tls_out.tlsa_usage |= 1<<usage;
2412 }
2413
2414 if (found)
2415 return OK;
2416
2417 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2418 return DEFER;
2419 }
2420 #endif /*SUPPORT_DANE*/
2421
2422
2423
2424 /*************************************************
2425 * Start a TLS session in a client *
2426 *************************************************/
2427
2428 /* Called from the smtp transport after STARTTLS has been accepted.
2429
2430 Argument:
2431 fd the fd of the connection
2432 host connected host (for messages and option-tests)
2433 addr the first address (for some randomness; can be NULL)
2434 tb transport (always smtp)
2435 tlsa_dnsa tlsa lookup, if DANE, else null
2436 tlsp record details of channel configuration here; must be non-NULL
2437 errstr error string pointer
2438
2439 Returns: Pointer to TLS session context, or NULL on error
2440 */
2441
2442 void *
2443 tls_client_start(int fd, host_item *host, address_item *addr,
2444 transport_instance * tb,
2445 #ifdef SUPPORT_DANE
2446 dns_answer * tlsa_dnsa,
2447 #endif
2448 tls_support * tlsp, uschar ** errstr)
2449 {
2450 smtp_transport_options_block * ob = tb
2451 ? (smtp_transport_options_block *)tb->options_block
2452 : &smtp_transport_option_defaults;
2453 exim_openssl_client_tls_ctx * exim_client_ctx;
2454 static uschar peerdn[256];
2455 uschar * expciphers;
2456 int rc;
2457 static uschar cipherbuf[256];
2458
2459 #ifndef DISABLE_OCSP
2460 BOOL request_ocsp = FALSE;
2461 BOOL require_ocsp = FALSE;
2462 #endif
2463
2464 rc = store_pool;
2465 store_pool = POOL_PERM;
2466 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx));
2467 store_pool = rc;
2468
2469 #ifdef SUPPORT_DANE
2470 tlsp->tlsa_usage = 0;
2471 #endif
2472
2473 #ifndef DISABLE_OCSP
2474 {
2475 # ifdef SUPPORT_DANE
2476 if ( tlsa_dnsa
2477 && ob->hosts_request_ocsp[0] == '*'
2478 && ob->hosts_request_ocsp[1] == '\0'
2479 )
2480 {
2481 /* Unchanged from default. Use a safer one under DANE */
2482 request_ocsp = TRUE;
2483 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2484 " {= {4}{$tls_out_tlsa_usage}} } "
2485 " {*}{}}";
2486 }
2487 # endif
2488
2489 if ((require_ocsp =
2490 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
2491 request_ocsp = TRUE;
2492 else
2493 # ifdef SUPPORT_DANE
2494 if (!request_ocsp)
2495 # endif
2496 request_ocsp =
2497 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2498 }
2499 #endif
2500
2501 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
2502 ob->tls_certificate, ob->tls_privatekey,
2503 #ifndef DISABLE_OCSP
2504 (void *)(long)request_ocsp,
2505 #endif
2506 addr, &client_static_cbinfo, errstr);
2507 if (rc != OK) return NULL;
2508
2509 tlsp->certificate_verified = FALSE;
2510 client_verify_callback_called = FALSE;
2511
2512 expciphers = NULL;
2513 #ifdef SUPPORT_DANE
2514 if (tlsa_dnsa)
2515 {
2516 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2517 other failures should be treated as problems. */
2518 if (ob->dane_require_tls_ciphers &&
2519 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2520 &expciphers, errstr))
2521 return NULL;
2522 if (expciphers && *expciphers == '\0')
2523 expciphers = NULL;
2524 }
2525 #endif
2526 if (!expciphers &&
2527 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2528 &expciphers, errstr))
2529 return NULL;
2530
2531 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2532 are separated by underscores. So that I can use either form in my tests, and
2533 also for general convenience, we turn underscores into hyphens here. */
2534
2535 if (expciphers)
2536 {
2537 uschar *s = expciphers;
2538 while (*s) { if (*s == '_') *s = '-'; s++; }
2539 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2540 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
2541 {
2542 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2543 return NULL;
2544 }
2545 }
2546
2547 #ifdef SUPPORT_DANE
2548 if (tlsa_dnsa)
2549 {
2550 SSL_CTX_set_verify(exim_client_ctx->ctx,
2551 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2552 verify_callback_client_dane);
2553
2554 if (!DANESSL_library_init())
2555 {
2556 tls_error(US"library init", host, NULL, errstr);
2557 return NULL;
2558 }
2559 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
2560 {
2561 tls_error(US"context init", host, NULL, errstr);
2562 return NULL;
2563 }
2564 }
2565 else
2566
2567 #endif
2568
2569 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
2570 client_static_cbinfo, errstr) != OK)
2571 return NULL;
2572
2573 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
2574 {
2575 tls_error(US"SSL_new", host, NULL, errstr);
2576 return NULL;
2577 }
2578 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
2579 SSL_set_fd(exim_client_ctx->ssl, fd);
2580 SSL_set_connect_state(exim_client_ctx->ssl);
2581
2582 if (ob->tls_sni)
2583 {
2584 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
2585 return NULL;
2586 if (!tlsp->sni)
2587 {
2588 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2589 }
2590 else if (!Ustrlen(tlsp->sni))
2591 tlsp->sni = NULL;
2592 else
2593 {
2594 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2595 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
2596 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
2597 #else
2598 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2599 tlsp->sni);
2600 #endif
2601 }
2602 }
2603
2604 #ifdef SUPPORT_DANE
2605 if (tlsa_dnsa)
2606 if (dane_tlsa_load(exim_client_ctx->ssl, host, tlsa_dnsa, errstr) != OK)
2607 return NULL;
2608 #endif
2609
2610 #ifndef DISABLE_OCSP
2611 /* Request certificate status at connection-time. If the server
2612 does OCSP stapling we will get the callback (set in tls_init()) */
2613 # ifdef SUPPORT_DANE
2614 if (request_ocsp)
2615 {
2616 const uschar * s;
2617 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2618 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2619 )
2620 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2621 this means we avoid the OCSP request, we wasted the setup
2622 cost in tls_init(). */
2623 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
2624 request_ocsp = require_ocsp
2625 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2626 }
2627 }
2628 # endif
2629
2630 if (request_ocsp)
2631 {
2632 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
2633 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2634 tlsp->ocsp = OCSP_NOT_RESP;
2635 }
2636 #endif
2637
2638 #ifndef DISABLE_EVENT
2639 client_static_cbinfo->event_action = tb ? tb->event_action : NULL;
2640 #endif
2641
2642 /* There doesn't seem to be a built-in timeout on connection. */
2643
2644 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2645 sigalrm_seen = FALSE;
2646 alarm(ob->command_timeout);
2647 rc = SSL_connect(exim_client_ctx->ssl);
2648 alarm(0);
2649
2650 #ifdef SUPPORT_DANE
2651 if (tlsa_dnsa)
2652 DANESSL_cleanup(exim_client_ctx->ssl);
2653 #endif
2654
2655 if (rc <= 0)
2656 {
2657 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
2658 return NULL;
2659 }
2660
2661 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2662
2663 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
2664
2665 construct_cipher_name(exim_client_ctx->ssl, cipherbuf, sizeof(cipherbuf), &tlsp->bits);
2666 tlsp->cipher = cipherbuf;
2667
2668 /* Record the certificate we presented */
2669 {
2670 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
2671 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
2672 }
2673
2674 tlsp->active.sock = fd;
2675 tlsp->active.tls_ctx = exim_client_ctx;
2676 return exim_client_ctx;
2677 }
2678
2679
2680
2681
2682
2683 static BOOL
2684 tls_refill(unsigned lim)
2685 {
2686 int error;
2687 int inbytes;
2688
2689 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2690 ssl_xfer_buffer, ssl_xfer_buffer_size);
2691
2692 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2693 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2694 MIN(ssl_xfer_buffer_size, lim));
2695 error = SSL_get_error(server_ssl, inbytes);
2696 if (smtp_receive_timeout > 0) alarm(0);
2697
2698 if (had_command_timeout) /* set by signal handler */
2699 smtp_command_timeout_exit(); /* does not return */
2700 if (had_command_sigterm)
2701 smtp_command_sigterm_exit();
2702 if (had_data_timeout)
2703 smtp_data_timeout_exit();
2704 if (had_data_sigint)
2705 smtp_data_sigint_exit();
2706
2707 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2708 closed down, not that the socket itself has been closed down. Revert to
2709 non-SSL handling. */
2710
2711 switch(error)
2712 {
2713 case SSL_ERROR_NONE:
2714 break;
2715
2716 case SSL_ERROR_ZERO_RETURN:
2717 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2718
2719 receive_getc = smtp_getc;
2720 receive_getbuf = smtp_getbuf;
2721 receive_get_cache = smtp_get_cache;
2722 receive_ungetc = smtp_ungetc;
2723 receive_feof = smtp_feof;
2724 receive_ferror = smtp_ferror;
2725 receive_smtp_buffered = smtp_buffered;
2726
2727 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2728 SSL_shutdown(server_ssl);
2729
2730 #ifndef DISABLE_OCSP
2731 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
2732 server_static_cbinfo->verify_stack = NULL;
2733 #endif
2734 SSL_free(server_ssl);
2735 SSL_CTX_free(server_ctx);
2736 server_ctx = NULL;
2737 server_ssl = NULL;
2738 tls_in.active.sock = -1;
2739 tls_in.active.tls_ctx = NULL;
2740 tls_in.bits = 0;
2741 tls_in.cipher = NULL;
2742 tls_in.peerdn = NULL;
2743 tls_in.sni = NULL;
2744
2745 return FALSE;
2746
2747 /* Handle genuine errors */
2748 case SSL_ERROR_SSL:
2749 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
2750 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2751 ssl_xfer_error = TRUE;
2752 return FALSE;
2753
2754 default:
2755 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2756 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
2757 debug_printf(" - syscall %s\n", strerror(errno));
2758 ssl_xfer_error = TRUE;
2759 return FALSE;
2760 }
2761
2762 #ifndef DISABLE_DKIM
2763 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2764 #endif
2765 ssl_xfer_buffer_hwm = inbytes;
2766 ssl_xfer_buffer_lwm = 0;
2767 return TRUE;
2768 }
2769
2770
2771 /*************************************************
2772 * TLS version of getc *
2773 *************************************************/
2774
2775 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2776 it refills the buffer via the SSL reading function.
2777
2778 Arguments: lim Maximum amount to read/buffer
2779 Returns: the next character or EOF
2780
2781 Only used by the server-side TLS.
2782 */
2783
2784 int
2785 tls_getc(unsigned lim)
2786 {
2787 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2788 if (!tls_refill(lim))
2789 return ssl_xfer_error ? EOF : smtp_getc(lim);
2790
2791 /* Something in the buffer; return next uschar */
2792
2793 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2794 }
2795
2796 uschar *
2797 tls_getbuf(unsigned * len)
2798 {
2799 unsigned size;
2800 uschar * buf;
2801
2802 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2803 if (!tls_refill(*len))
2804 {
2805 if (!ssl_xfer_error) return smtp_getbuf(len);
2806 *len = 0;
2807 return NULL;
2808 }
2809
2810 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
2811 size = *len;
2812 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
2813 ssl_xfer_buffer_lwm += size;
2814 *len = size;
2815 return buf;
2816 }
2817
2818
2819 void
2820 tls_get_cache()
2821 {
2822 #ifndef DISABLE_DKIM
2823 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2824 if (n > 0)
2825 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
2826 #endif
2827 }
2828
2829
2830 BOOL
2831 tls_could_read(void)
2832 {
2833 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
2834 }
2835
2836
2837 /*************************************************
2838 * Read bytes from TLS channel *
2839 *************************************************/
2840
2841 /*
2842 Arguments:
2843 ct_ctx client context pointer, or NULL for the one global server context
2844 buff buffer of data
2845 len size of buffer
2846
2847 Returns: the number of bytes read
2848 -1 after a failed read, including EOF
2849
2850 Only used by the client-side TLS.
2851 */
2852
2853 int
2854 tls_read(void * ct_ctx, uschar *buff, size_t len)
2855 {
2856 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
2857 int inbytes;
2858 int error;
2859
2860 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2861 buff, (unsigned int)len);
2862
2863 inbytes = SSL_read(ssl, CS buff, len);
2864 error = SSL_get_error(ssl, inbytes);
2865
2866 if (error == SSL_ERROR_ZERO_RETURN)
2867 {
2868 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2869 return -1;
2870 }
2871 else if (error != SSL_ERROR_NONE)
2872 return -1;
2873
2874 return inbytes;
2875 }
2876
2877
2878
2879
2880
2881 /*************************************************
2882 * Write bytes down TLS channel *
2883 *************************************************/
2884
2885 /*
2886 Arguments:
2887 ct_ctx client context pointer, or NULL for the one global server context
2888 buff buffer of data
2889 len number of bytes
2890 more further data expected soon
2891
2892 Returns: the number of bytes after a successful write,
2893 -1 after a failed write
2894
2895 Used by both server-side and client-side TLS.
2896 */
2897
2898 int
2899 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
2900 {
2901 int outbytes, error, left;
2902 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
2903 static gstring * corked = NULL;
2904
2905 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
2906 buff, (unsigned long)len, more ? ", more" : "");
2907
2908 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2909 "more" is notified. This hack is only ok if small amounts are involved AND only
2910 one stream does it, in one context (i.e. no store reset). Currently it is used
2911 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2912
2913 if (!ct_ctx && (more || corked))
2914 {
2915 corked = string_catn(corked, buff, len);
2916 if (more)
2917 return len;
2918 buff = CUS corked->s;
2919 len = corked->ptr;
2920 corked = NULL;
2921 }
2922
2923 for (left = len; left > 0;)
2924 {
2925 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
2926 outbytes = SSL_write(ssl, CS buff, left);
2927 error = SSL_get_error(ssl, outbytes);
2928 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2929 switch (error)
2930 {
2931 case SSL_ERROR_SSL:
2932 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
2933 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2934 return -1;
2935
2936 case SSL_ERROR_NONE:
2937 left -= outbytes;
2938 buff += outbytes;
2939 break;
2940
2941 case SSL_ERROR_ZERO_RETURN:
2942 log_write(0, LOG_MAIN, "SSL channel closed on write");
2943 return -1;
2944
2945 case SSL_ERROR_SYSCALL:
2946 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2947 sender_fullhost ? sender_fullhost : US"<unknown>",
2948 strerror(errno));
2949 return -1;
2950
2951 default:
2952 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2953 return -1;
2954 }
2955 }
2956 return len;
2957 }
2958
2959
2960
2961 /*************************************************
2962 * Close down a TLS session *
2963 *************************************************/
2964
2965 /* This is also called from within a delivery subprocess forked from the
2966 daemon, to shut down the TLS library, without actually doing a shutdown (which
2967 would tamper with the SSL session in the parent process).
2968
2969 Arguments:
2970 ct_ctx client TLS context pointer, or NULL for the one global server context
2971 shutdown 1 if TLS close-alert is to be sent,
2972 2 if also response to be waited for
2973
2974 Returns: nothing
2975
2976 Used by both server-side and client-side TLS.
2977 */
2978
2979 void
2980 tls_close(void * ct_ctx, int shutdown)
2981 {
2982 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
2983 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
2984 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
2985 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
2986
2987 if (*fdp < 0) return; /* TLS was not active */
2988
2989 if (shutdown)
2990 {
2991 int rc;
2992 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2993 shutdown > 1 ? " (with response-wait)" : "");
2994
2995 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
2996 && shutdown > 1)
2997 {
2998 alarm(2);
2999 rc = SSL_shutdown(*sslp); /* wait for response */
3000 alarm(0);
3001 }
3002
3003 if (rc < 0) DEBUG(D_tls)
3004 {
3005 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3006 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
3007 }
3008 }
3009
3010 #ifndef DISABLE_OCSP
3011 if (!o_ctx) /* server side */
3012 {
3013 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3014 server_static_cbinfo->verify_stack = NULL;
3015 }
3016 #endif
3017
3018 SSL_CTX_free(*ctxp);
3019 SSL_free(*sslp);
3020 *ctxp = NULL;
3021 *sslp = NULL;
3022 *fdp = -1;
3023 }
3024
3025
3026
3027
3028 /*************************************************
3029 * Let tls_require_ciphers be checked at startup *
3030 *************************************************/
3031
3032 /* The tls_require_ciphers option, if set, must be something which the
3033 library can parse.
3034
3035 Returns: NULL on success, or error message
3036 */
3037
3038 uschar *
3039 tls_validate_require_cipher(void)
3040 {
3041 SSL_CTX *ctx;
3042 uschar *s, *expciphers, *err;
3043
3044 /* this duplicates from tls_init(), we need a better "init just global
3045 state, for no specific purpose" singleton function of our own */
3046
3047 SSL_load_error_strings();
3048 OpenSSL_add_ssl_algorithms();
3049 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
3050 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
3051 list of available digests. */
3052 EVP_add_digest(EVP_sha256());
3053 #endif
3054
3055 if (!(tls_require_ciphers && *tls_require_ciphers))
3056 return NULL;
3057
3058 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3059 &err))
3060 return US"failed to expand tls_require_ciphers";
3061
3062 if (!(expciphers && *expciphers))
3063 return NULL;
3064
3065 /* normalisation ripped from above */
3066 s = expciphers;
3067 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
3068
3069 err = NULL;
3070
3071 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3072 if (!(ctx = SSL_CTX_new(TLS_server_method())))
3073 #else
3074 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
3075 #endif
3076 {
3077 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3078 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
3079 }
3080
3081 DEBUG(D_tls)
3082 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3083
3084 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
3085 {
3086 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3087 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3088 expciphers, ssl_errstring);
3089 }
3090
3091 SSL_CTX_free(ctx);
3092
3093 return err;
3094 }
3095
3096
3097
3098
3099 /*************************************************
3100 * Report the library versions. *
3101 *************************************************/
3102
3103 /* There have historically been some issues with binary compatibility in
3104 OpenSSL libraries; if Exim (like many other applications) is built against
3105 one version of OpenSSL but the run-time linker picks up another version,
3106 it can result in serious failures, including crashing with a SIGSEGV. So
3107 report the version found by the compiler and the run-time version.
3108
3109 Note: some OS vendors backport security fixes without changing the version
3110 number/string, and the version date remains unchanged. The _build_ date
3111 will change, so we can more usefully assist with version diagnosis by also
3112 reporting the build date.
3113
3114 Arguments: a FILE* to print the results to
3115 Returns: nothing
3116 */
3117
3118 void
3119 tls_version_report(FILE *f)
3120 {
3121 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
3122 " Runtime: %s\n"
3123 " : %s\n",
3124 OPENSSL_VERSION_TEXT,
3125 SSLeay_version(SSLEAY_VERSION),
3126 SSLeay_version(SSLEAY_BUILT_ON));
3127 /* third line is 38 characters for the %s and the line is 73 chars long;
3128 the OpenSSL output includes a "built on: " prefix already. */
3129 }
3130
3131
3132
3133
3134 /*************************************************
3135 * Random number generation *
3136 *************************************************/
3137
3138 /* Pseudo-random number generation. The result is not expected to be
3139 cryptographically strong but not so weak that someone will shoot themselves
3140 in the foot using it as a nonce in input in some email header scheme or
3141 whatever weirdness they'll twist this into. The result should handle fork()
3142 and avoid repeating sequences. OpenSSL handles that for us.
3143
3144 Arguments:
3145 max range maximum
3146 Returns a random number in range [0, max-1]
3147 */
3148
3149 int
3150 vaguely_random_number(int max)
3151 {
3152 unsigned int r;
3153 int i, needed_len;
3154 static pid_t pidlast = 0;
3155 pid_t pidnow;
3156 uschar *p;
3157 uschar smallbuf[sizeof(r)];
3158
3159 if (max <= 1)
3160 return 0;
3161
3162 pidnow = getpid();
3163 if (pidnow != pidlast)
3164 {
3165 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3166 is unique for each thread", this doesn't apparently apply across processes,
3167 so our own warning from vaguely_random_number_fallback() applies here too.
3168 Fix per PostgreSQL. */
3169 if (pidlast != 0)
3170 RAND_cleanup();
3171 pidlast = pidnow;
3172 }
3173
3174 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3175 if (!RAND_status())
3176 {
3177 randstuff r;
3178 gettimeofday(&r.tv, NULL);
3179 r.p = getpid();
3180
3181 RAND_seed(US (&r), sizeof(r));
3182 }
3183 /* We're after pseudo-random, not random; if we still don't have enough data
3184 in the internal PRNG then our options are limited. We could sleep and hope
3185 for entropy to come along (prayer technique) but if the system is so depleted
3186 in the first place then something is likely to just keep taking it. Instead,
3187 we'll just take whatever little bit of pseudo-random we can still manage to
3188 get. */
3189
3190 needed_len = sizeof(r);
3191 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3192 asked for a number less than 10. */
3193 for (r = max, i = 0; r; ++i)
3194 r >>= 1;
3195 i = (i + 7) / 8;
3196 if (i < needed_len)
3197 needed_len = i;
3198
3199 #ifdef EXIM_HAVE_RAND_PSEUDO
3200 /* We do not care if crypto-strong */
3201 i = RAND_pseudo_bytes(smallbuf, needed_len);
3202 #else
3203 i = RAND_bytes(smallbuf, needed_len);
3204 #endif
3205
3206 if (i < 0)
3207 {
3208 DEBUG(D_all)
3209 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3210 return vaguely_random_number_fallback(max);
3211 }
3212
3213 r = 0;
3214 for (p = smallbuf; needed_len; --needed_len, ++p)
3215 {
3216 r *= 256;
3217 r += *p;
3218 }
3219
3220 /* We don't particularly care about weighted results; if someone wants
3221 smooth distribution and cares enough then they should submit a patch then. */
3222 return r % max;
3223 }
3224
3225
3226
3227
3228 /*************************************************
3229 * OpenSSL option parse *
3230 *************************************************/
3231
3232 /* Parse one option for tls_openssl_options_parse below
3233
3234 Arguments:
3235 name one option name
3236 value place to store a value for it
3237 Returns success or failure in parsing
3238 */
3239
3240
3241
3242 static BOOL
3243 tls_openssl_one_option_parse(uschar *name, long *value)
3244 {
3245 int first = 0;
3246 int last = exim_openssl_options_size;
3247 while (last > first)
3248 {
3249 int middle = (first + last)/2;
3250 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3251 if (c == 0)
3252 {
3253 *value = exim_openssl_options[middle].value;
3254 return TRUE;
3255 }
3256 else if (c > 0)
3257 first = middle + 1;
3258 else
3259 last = middle;
3260 }
3261 return FALSE;
3262 }
3263
3264
3265
3266
3267 /*************************************************
3268 * OpenSSL option parsing logic *
3269 *************************************************/
3270
3271 /* OpenSSL has a number of compatibility options which an administrator might
3272 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3273 we look like log_selector.
3274
3275 Arguments:
3276 option_spec the administrator-supplied string of options
3277 results ptr to long storage for the options bitmap
3278 Returns success or failure
3279 */
3280
3281 BOOL
3282 tls_openssl_options_parse(uschar *option_spec, long *results)
3283 {
3284 long result, item;
3285 uschar *s, *end;
3286 uschar keep_c;
3287 BOOL adding, item_parsed;
3288
3289 result = SSL_OP_NO_TICKET;
3290 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3291 * from default because it increases BEAST susceptibility. */
3292 #ifdef SSL_OP_NO_SSLv2
3293 result |= SSL_OP_NO_SSLv2;
3294 #endif
3295 #ifdef SSL_OP_SINGLE_DH_USE
3296 result |= SSL_OP_SINGLE_DH_USE;
3297 #endif
3298
3299 if (!option_spec)
3300 {
3301 *results = result;
3302 return TRUE;
3303 }
3304
3305 for (s=option_spec; *s != '\0'; /**/)
3306 {
3307 while (isspace(*s)) ++s;
3308 if (*s == '\0')
3309 break;
3310 if (*s != '+' && *s != '-')
3311 {
3312 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3313 "+ or - expected but found \"%s\"\n", s);
3314 return FALSE;
3315 }
3316 adding = *s++ == '+';
3317 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3318 keep_c = *end;
3319 *end = '\0';
3320 item_parsed = tls_openssl_one_option_parse(s, &item);
3321 *end = keep_c;
3322 if (!item_parsed)
3323 {
3324 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3325 return FALSE;
3326 }
3327 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3328 adding ? "adding" : "removing", result, item, s);
3329 if (adding)
3330 result |= item;
3331 else
3332 result &= ~item;
3333 s = end;
3334 }
3335
3336 *results = result;
3337 return TRUE;
3338 }
3339
3340 #endif /*!MACRO_PREDEF*/
3341 /* vi: aw ai sw=2
3342 */
3343 /* End of tls-openssl.c */
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