Docs: fix definition of msg:fail:delivery event
[exim.git] / src / src / tls-openssl.c
CommitLineData
059ec3d9
PH
1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
d4e5e70b 5/* Copyright (c) University of Cambridge 1995 - 2017 */
059ec3d9
PH
6/* See the file NOTICE for conditions of use and distribution. */
7
f5d78688
JH
8/* Portions Copyright (c) The OpenSSL Project 1999 */
9
059ec3d9
PH
10/* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11library. It is #included into the tls.c file when that library is used. The
12code herein is based on a patch that was originally contributed by Steve
13Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
14
15No cryptographic code is included in Exim. All this module does is to call
16functions 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>
10ca4f1c
JH
25#ifndef OPENSSL_NO_ECDH
26# include <openssl/ec.h>
27#endif
f2de3a33 28#ifndef DISABLE_OCSP
e51c7be2 29# include <openssl/ocsp.h>
3f7eeb86 30#endif
85098ee7
JH
31#ifdef EXPERIMENTAL_DANE
32# include <danessl.h>
33#endif
34
3f7eeb86 35
f2de3a33
JH
36#ifndef DISABLE_OCSP
37# define EXIM_OCSP_SKEW_SECONDS (300L)
38# define EXIM_OCSP_MAX_AGE (-1L)
3f7eeb86 39#endif
059ec3d9 40
3bcbbbe2 41#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
e51c7be2 42# define EXIM_HAVE_OPENSSL_TLSEXT
3bcbbbe2 43#endif
c8dfb21d
JH
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
34e3241d
PP
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# endif
73# if OPENSSL_VERSION_NUMBER >= 0x010000000L \
2dfb468b 74 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
34e3241d
PP
75# define EXIM_HAVE_OPENSSL_CHECKHOST
76# endif
11aa88b0 77#endif
10ca4f1c 78
11aa88b0
RA
79#if !defined(LIBRESSL_VERSION_NUMBER) \
80 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
10ca4f1c
JH
81# if !defined(OPENSSL_NO_ECDH)
82# if OPENSSL_VERSION_NUMBER >= 0x0090800fL
83# define EXIM_HAVE_ECDH
84# endif
85# if OPENSSL_VERSION_NUMBER >= 0x10002000L
10ca4f1c
JH
86# define EXIM_HAVE_OPENSSL_EC_NIST2NID
87# endif
88# endif
2dfb468b 89#endif
3bcbbbe2 90
67791ce4
JH
91#if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
92# warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
93# define DISABLE_OCSP
94#endif
95
059ec3d9
PH
96/* Structure for collecting random data for seeding. */
97
98typedef struct randstuff {
9e3331ea
TK
99 struct timeval tv;
100 pid_t p;
059ec3d9
PH
101} randstuff;
102
103/* Local static variables */
104
a2ff477a
JH
105static BOOL client_verify_callback_called = FALSE;
106static BOOL server_verify_callback_called = FALSE;
059ec3d9
PH
107static const uschar *sid_ctx = US"exim";
108
d4f09789
PP
109/* We have three different contexts to care about.
110
111Simple case: client, `client_ctx`
112 As a client, we can be doing a callout or cut-through delivery while receiving
113 a message. So we have a client context, which should have options initialised
114 from the SMTP Transport.
115
116Server:
117 There are two cases: with and without ServerNameIndication from the client.
118 Given TLS SNI, we can be using different keys, certs and various other
119 configuration settings, because they're re-expanded with $tls_sni set. This
120 allows vhosting with TLS. This SNI is sent in the handshake.
121 A client might not send SNI, so we need a fallback, and an initial setup too.
122 So as a server, we start out using `server_ctx`.
123 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
124 `server_sni` from `server_ctx` and then initialise settings by re-expanding
125 configuration.
126*/
127
817d9f57
JH
128static SSL_CTX *client_ctx = NULL;
129static SSL_CTX *server_ctx = NULL;
130static SSL *client_ssl = NULL;
131static SSL *server_ssl = NULL;
389ca47a 132
35731706 133#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57 134static SSL_CTX *server_sni = NULL;
35731706 135#endif
059ec3d9
PH
136
137static char ssl_errstring[256];
138
139static int ssl_session_timeout = 200;
a2ff477a
JH
140static BOOL client_verify_optional = FALSE;
141static BOOL server_verify_optional = FALSE;
059ec3d9 142
f5d78688 143static BOOL reexpand_tls_files_for_sni = FALSE;
059ec3d9
PH
144
145
7be682ca
PP
146typedef struct tls_ext_ctx_cb {
147 uschar *certificate;
148 uschar *privatekey;
f2de3a33 149#ifndef DISABLE_OCSP
f5d78688 150 BOOL is_server;
c3033f13 151 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
f5d78688
JH
152 union {
153 struct {
154 uschar *file;
155 uschar *file_expanded;
156 OCSP_RESPONSE *response;
157 } server;
158 struct {
44662487
JH
159 X509_STORE *verify_store; /* non-null if status requested */
160 BOOL verify_required;
f5d78688
JH
161 } client;
162 } u_ocsp;
3f7eeb86 163#endif
7be682ca
PP
164 uschar *dhparam;
165 /* these are cached from first expand */
166 uschar *server_cipher_list;
167 /* only passed down to tls_error: */
168 host_item *host;
55414b25 169 const uschar * verify_cert_hostnames;
0cbf2b82 170#ifndef DISABLE_EVENT
a7538db1
JH
171 uschar * event_action;
172#endif
7be682ca
PP
173} tls_ext_ctx_cb;
174
175/* should figure out a cleanup of API to handle state preserved per
176implementation, for various reasons, which can be void * in the APIs.
177For now, we hack around it. */
817d9f57
JH
178tls_ext_ctx_cb *client_static_cbinfo = NULL;
179tls_ext_ctx_cb *server_static_cbinfo = NULL;
7be682ca
PP
180
181static int
983207c1 182setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
cf0c6164 183 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
059ec3d9 184
3f7eeb86 185/* Callbacks */
3bcbbbe2 186#ifdef EXIM_HAVE_OPENSSL_TLSEXT
3f7eeb86 187static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
3bcbbbe2 188#endif
f2de3a33 189#ifndef DISABLE_OCSP
f5d78688 190static int tls_server_stapling_cb(SSL *s, void *arg);
3f7eeb86
PP
191#endif
192
059ec3d9
PH
193
194/*************************************************
195* Handle TLS error *
196*************************************************/
197
198/* Called from lots of places when errors occur before actually starting to do
199the TLS handshake, that is, while the session is still in clear. Always returns
200DEFER for a server and FAIL for a client so that most calls can use "return
201tls_error(...)" to do this processing and then give an appropriate return. A
202single function is used for both server and client, because it is called from
203some shared functions.
204
205Argument:
206 prefix text to include in the logged error
207 host NULL if setting up a server;
208 the connected host if setting up a client
7199e1ee 209 msg error message or NULL if we should ask OpenSSL
cf0c6164 210 errstr pointer to output error message
059ec3d9
PH
211
212Returns: OK/DEFER/FAIL
213*/
214
215static int
cf0c6164 216tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
059ec3d9 217{
c562fd30 218if (!msg)
7199e1ee
TF
219 {
220 ERR_error_string(ERR_get_error(), ssl_errstring);
cf0c6164 221 msg = US ssl_errstring;
7199e1ee
TF
222 }
223
cf0c6164
JH
224if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg);
225return host ? FAIL : DEFER;
059ec3d9
PH
226}
227
228
229
c8dfb21d 230#ifdef EXIM_HAVE_EPHEM_RSA_KEX
059ec3d9
PH
231/*************************************************
232* Callback to generate RSA key *
233*************************************************/
234
235/*
236Arguments:
237 s SSL connection
238 export not used
239 keylength keylength
240
241Returns: pointer to generated key
242*/
243
244static RSA *
245rsa_callback(SSL *s, int export, int keylength)
246{
247RSA *rsa_key;
c8dfb21d
JH
248#ifdef EXIM_HAVE_RSA_GENKEY_EX
249BIGNUM *bn = BN_new();
250#endif
251
059ec3d9
PH
252export = export; /* Shut picky compilers up */
253DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
c8dfb21d
JH
254
255#ifdef EXIM_HAVE_RSA_GENKEY_EX
256if ( !BN_set_word(bn, (unsigned long)RSA_F4)
f2cb6292 257 || !(rsa_key = RSA_new())
c8dfb21d
JH
258 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
259 )
260#else
23bb6982 261if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
c8dfb21d
JH
262#endif
263
059ec3d9
PH
264 {
265 ERR_error_string(ERR_get_error(), ssl_errstring);
266 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
267 ssl_errstring);
268 return NULL;
269 }
270return rsa_key;
271}
c8dfb21d 272#endif
059ec3d9
PH
273
274
275
f5d78688 276/* Extreme debug
f2de3a33 277#ifndef DISABLE_OCSP
f5d78688
JH
278void
279x509_store_dump_cert_s_names(X509_STORE * store)
280{
281STACK_OF(X509_OBJECT) * roots= store->objs;
282int i;
283static uschar name[256];
284
285for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
286 {
287 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
288 if(tmp_obj->type == X509_LU_X509)
289 {
290 X509 * current_cert= tmp_obj->data.x509;
291 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
f69979cf 292 name[sizeof(name)-1] = '\0';
f5d78688
JH
293 debug_printf(" %s\n", name);
294 }
295 }
296}
297#endif
298*/
299
059ec3d9 300
0cbf2b82 301#ifndef DISABLE_EVENT
f69979cf
JH
302static int
303verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
304 BOOL *calledp, const BOOL *optionalp, const uschar * what)
305{
306uschar * ev;
307uschar * yield;
308X509 * old_cert;
309
310ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
311if (ev)
312 {
aaba7d03 313 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
f69979cf
JH
314 old_cert = tlsp->peercert;
315 tlsp->peercert = X509_dup(cert);
316 /* NB we do not bother setting peerdn */
317 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
318 {
319 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
320 "depth=%d cert=%s: %s",
321 tlsp == &tls_out ? deliver_host_address : sender_host_address,
322 what, depth, dn, yield);
323 *calledp = TRUE;
324 if (!*optionalp)
325 {
326 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
327 return 1; /* reject (leaving peercert set) */
328 }
329 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
330 "(host in tls_try_verify_hosts)\n");
331 }
332 X509_free(tlsp->peercert);
333 tlsp->peercert = old_cert;
334 }
335return 0;
336}
337#endif
338
059ec3d9
PH
339/*************************************************
340* Callback for verification *
341*************************************************/
342
343/* The SSL library does certificate verification if set up to do so. This
344callback has the current yes/no state is in "state". If verification succeeded,
f69979cf
JH
345we set the certificate-verified flag. If verification failed, what happens
346depends on whether the client is required to present a verifiable certificate
347or not.
059ec3d9
PH
348
349If verification is optional, we change the state to yes, but still log the
350verification error. For some reason (it really would help to have proper
351documentation of OpenSSL), this callback function then gets called again, this
f69979cf
JH
352time with state = 1. We must take care not to set the private verified flag on
353the second time through.
059ec3d9
PH
354
355Note: this function is not called if the client fails to present a certificate
356when asked. We get here only if a certificate has been received. Handling of
357optional verification for this case is done when requesting SSL to verify, by
358setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
359
a7538db1
JH
360May be called multiple times for different issues with a certificate, even
361for a given "depth" in the certificate chain.
362
059ec3d9 363Arguments:
f2f2c91b
JH
364 preverify_ok current yes/no state as 1/0
365 x509ctx certificate information.
366 tlsp per-direction (client vs. server) support data
367 calledp has-been-called flag
368 optionalp verification-is-optional flag
059ec3d9 369
f2f2c91b 370Returns: 0 if verification should fail, otherwise 1
059ec3d9
PH
371*/
372
373static int
f2f2c91b 374verify_callback(int preverify_ok, X509_STORE_CTX *x509ctx,
421aff85 375 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
059ec3d9 376{
421aff85 377X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
a7538db1 378int depth = X509_STORE_CTX_get_error_depth(x509ctx);
f69979cf 379uschar dn[256];
059ec3d9 380
f69979cf
JH
381X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
382dn[sizeof(dn)-1] = '\0';
059ec3d9 383
f2f2c91b 384if (preverify_ok == 0)
059ec3d9 385 {
4c01d6ab
JH
386 log_write(0, LOG_MAIN, "[%s] SSL verify error: depth=%d error=%s cert=%s",
387 tlsp == &tls_out ? deliver_host_address : sender_host_address,
a7538db1 388 depth,
421aff85 389 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
f69979cf 390 dn);
a2ff477a 391 *calledp = TRUE;
9d1c15ef
JH
392 if (!*optionalp)
393 {
f69979cf
JH
394 if (!tlsp->peercert)
395 tlsp->peercert = X509_dup(cert); /* record failing cert */
396 return 0; /* reject */
9d1c15ef 397 }
059ec3d9
PH
398 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
399 "tls_try_verify_hosts)\n");
059ec3d9
PH
400 }
401
a7538db1 402else if (depth != 0)
059ec3d9 403 {
f69979cf 404 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
f2de3a33 405#ifndef DISABLE_OCSP
f5d78688
JH
406 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
407 { /* client, wanting stapling */
408 /* Add the server cert's signing chain as the one
409 for the verification of the OCSP stapled information. */
94431adb 410
f5d78688 411 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
421aff85 412 cert))
f5d78688 413 ERR_clear_error();
c3033f13 414 sk_X509_push(client_static_cbinfo->verify_stack, cert);
f5d78688
JH
415 }
416#endif
0cbf2b82 417#ifndef DISABLE_EVENT
f69979cf
JH
418 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
419 return 0; /* reject, with peercert set */
a7538db1 420#endif
059ec3d9
PH
421 }
422else
423 {
55414b25 424 const uschar * verify_cert_hostnames;
e51c7be2 425
e51c7be2
JH
426 if ( tlsp == &tls_out
427 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
428 /* client, wanting hostname check */
e51c7be2 429 {
f69979cf 430
740f36d4 431#ifdef EXIM_HAVE_OPENSSL_CHECKHOST
f69979cf
JH
432# ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
433# define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
434# endif
435# ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
436# define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
437# endif
e51c7be2 438 int sep = 0;
55414b25 439 const uschar * list = verify_cert_hostnames;
e51c7be2 440 uschar * name;
d8e7834a
JH
441 int rc;
442 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
f40d5be3 443 if ((rc = X509_check_host(cert, CCS name, 0,
8d692470 444 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
740f36d4
JH
445 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
446 NULL)))
d8e7834a
JH
447 {
448 if (rc < 0)
449 {
93a6fce2 450 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
8cfd0f7b 451 deliver_host_address);
d8e7834a
JH
452 name = NULL;
453 }
e51c7be2 454 break;
d8e7834a 455 }
e51c7be2 456 if (!name)
f69979cf 457#else
e51c7be2 458 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
f69979cf 459#endif
e51c7be2
JH
460 {
461 log_write(0, LOG_MAIN,
b999c483
JH
462 "[%s] SSL verify error: certificate name mismatch: "
463 "DN=\"%s\" H=\"%s\"",
464 deliver_host_address, dn, verify_cert_hostnames);
a3ef7310
JH
465 *calledp = TRUE;
466 if (!*optionalp)
f69979cf
JH
467 {
468 if (!tlsp->peercert)
469 tlsp->peercert = X509_dup(cert); /* record failing cert */
470 return 0; /* reject */
471 }
a3ef7310
JH
472 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
473 "tls_try_verify_hosts)\n");
e51c7be2 474 }
f69979cf 475 }
e51c7be2 476
0cbf2b82 477#ifndef DISABLE_EVENT
f69979cf
JH
478 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
479 return 0; /* reject, with peercert set */
e51c7be2
JH
480#endif
481
93dcb1c2 482 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
f69979cf 483 *calledp ? "" : " authenticated", dn);
93dcb1c2
JH
484 if (!*calledp) tlsp->certificate_verified = TRUE;
485 *calledp = TRUE;
059ec3d9
PH
486 }
487
a7538db1 488return 1; /* accept, at least for this level */
059ec3d9
PH
489}
490
a2ff477a 491static int
f2f2c91b 492verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
a2ff477a 493{
f2f2c91b
JH
494return verify_callback(preverify_ok, x509ctx, &tls_out,
495 &client_verify_callback_called, &client_verify_optional);
a2ff477a
JH
496}
497
498static int
f2f2c91b 499verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
a2ff477a 500{
f2f2c91b
JH
501return verify_callback(preverify_ok, x509ctx, &tls_in,
502 &server_verify_callback_called, &server_verify_optional);
a2ff477a
JH
503}
504
059ec3d9 505
e5cccda9 506#ifdef EXPERIMENTAL_DANE
53a7196b 507
e5cccda9
JH
508/* This gets called *by* the dane library verify callback, which interposes
509itself.
510*/
511static int
f2f2c91b 512verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
e5cccda9
JH
513{
514X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
f69979cf 515uschar dn[256];
83b27293 516int depth = X509_STORE_CTX_get_error_depth(x509ctx);
5c75db2e 517#ifndef DISABLE_EVENT
f69979cf 518BOOL dummy_called, optional = FALSE;
83b27293 519#endif
e5cccda9 520
f69979cf
JH
521X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
522dn[sizeof(dn)-1] = '\0';
e5cccda9 523
f2f2c91b
JH
524DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
525 preverify_ok ? "ok":"BAD", depth, dn);
e5cccda9 526
0cbf2b82 527#ifndef DISABLE_EVENT
f69979cf
JH
528 if (verify_event(&tls_out, cert, depth, dn,
529 &dummy_called, &optional, US"DANE"))
530 return 0; /* reject, with peercert set */
83b27293
JH
531#endif
532
f2f2c91b 533if (preverify_ok == 1)
53a7196b 534 tls_out.dane_verified =
e5cccda9 535 tls_out.certificate_verified = TRUE;
f2f2c91b
JH
536else
537 {
538 int err = X509_STORE_CTX_get_error(x509ctx);
539 DEBUG(D_tls)
540 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
3c51463e 541 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
f2f2c91b
JH
542 preverify_ok = 1;
543 }
544return preverify_ok;
e5cccda9 545}
53a7196b
JH
546
547#endif /*EXPERIMENTAL_DANE*/
e5cccda9 548
059ec3d9
PH
549
550/*************************************************
551* Information callback *
552*************************************************/
553
554/* The SSL library functions call this from time to time to indicate what they
7be682ca
PP
555are doing. We copy the string to the debugging output when TLS debugging has
556been requested.
059ec3d9
PH
557
558Arguments:
559 s the SSL connection
560 where
561 ret
562
563Returns: nothing
564*/
565
566static void
567info_callback(SSL *s, int where, int ret)
568{
569where = where;
570ret = ret;
571DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
572}
573
574
575
576/*************************************************
577* Initialize for DH *
578*************************************************/
579
580/* If dhparam is set, expand it, and load up the parameters for DH encryption.
581
582Arguments:
038597d2 583 sctx The current SSL CTX (inbound or outbound)
a799883d 584 dhparam DH parameter file or fixed parameter identity string
7199e1ee 585 host connected host, if client; NULL if server
cf0c6164 586 errstr error string pointer
059ec3d9
PH
587
588Returns: TRUE if OK (nothing to set up, or setup worked)
589*/
590
591static BOOL
cf0c6164 592init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
059ec3d9 593{
059ec3d9
PH
594BIO *bio;
595DH *dh;
596uschar *dhexpanded;
a799883d 597const char *pem;
059ec3d9 598
cf0c6164 599if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
059ec3d9
PH
600 return FALSE;
601
0df4ab80 602if (!dhexpanded || !*dhexpanded)
a799883d 603 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
a799883d 604else if (dhexpanded[0] == '/')
059ec3d9 605 {
0df4ab80 606 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
059ec3d9 607 {
7199e1ee 608 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
cf0c6164 609 host, US strerror(errno), errstr);
a799883d 610 return FALSE;
059ec3d9 611 }
a799883d
PP
612 }
613else
614 {
615 if (Ustrcmp(dhexpanded, "none") == 0)
059ec3d9 616 {
a799883d
PP
617 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
618 return TRUE;
059ec3d9 619 }
a799883d 620
0df4ab80 621 if (!(pem = std_dh_prime_named(dhexpanded)))
a799883d
PP
622 {
623 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
cf0c6164 624 host, US strerror(errno), errstr);
a799883d
PP
625 return FALSE;
626 }
627 bio = BIO_new_mem_buf(CS pem, -1);
628 }
629
0df4ab80 630if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
a799883d 631 {
059ec3d9 632 BIO_free(bio);
a799883d 633 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
cf0c6164 634 host, NULL, errstr);
a799883d
PP
635 return FALSE;
636 }
637
638/* Even if it is larger, we silently return success rather than cause things
639 * to fail out, so that a too-large DH will not knock out all TLS; it's a
640 * debatable choice. */
641if ((8*DH_size(dh)) > tls_dh_max_bits)
642 {
643 DEBUG(D_tls)
644 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
645 8*DH_size(dh), tls_dh_max_bits);
646 }
647else
648 {
649 SSL_CTX_set_tmp_dh(sctx, dh);
650 DEBUG(D_tls)
651 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
652 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
059ec3d9
PH
653 }
654
a799883d
PP
655DH_free(dh);
656BIO_free(bio);
657
658return TRUE;
059ec3d9
PH
659}
660
661
662
663
038597d2
PP
664/*************************************************
665* Initialize for ECDH *
666*************************************************/
667
668/* Load parameters for ECDH encryption.
669
670For now, we stick to NIST P-256 because: it's simple and easy to configure;
671it avoids any patent issues that might bite redistributors; despite events in
672the news and concerns over curve choices, we're not cryptographers, we're not
673pretending to be, and this is "good enough" to be better than no support,
674protecting against most adversaries. Given another year or two, there might
675be sufficient clarity about a "right" way forward to let us make an informed
676decision, instead of a knee-jerk reaction.
677
678Longer-term, we should look at supporting both various named curves and
679external files generated with "openssl ecparam", much as we do for init_dh().
680We should also support "none" as a value, to explicitly avoid initialisation.
681
682Patches welcome.
683
684Arguments:
685 sctx The current SSL CTX (inbound or outbound)
686 host connected host, if client; NULL if server
cf0c6164 687 errstr error string pointer
038597d2
PP
688
689Returns: TRUE if OK (nothing to set up, or setup worked)
690*/
691
692static BOOL
cf0c6164 693init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
038597d2 694{
63f0dbe0
JH
695#ifdef OPENSSL_NO_ECDH
696return TRUE;
697#else
698
10ca4f1c
JH
699EC_KEY * ecdh;
700uschar * exp_curve;
701int nid;
702BOOL rv;
703
038597d2
PP
704if (host) /* No ECDH setup for clients, only for servers */
705 return TRUE;
706
10ca4f1c 707# ifndef EXIM_HAVE_ECDH
038597d2
PP
708DEBUG(D_tls)
709 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
710return TRUE;
038597d2 711# else
10ca4f1c 712
cf0c6164 713if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
10ca4f1c
JH
714 return FALSE;
715if (!exp_curve || !*exp_curve)
716 return TRUE;
717
8e53a4fc 718/* "auto" needs to be handled carefully.
4c04137d 719 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
8e53a4fc 720 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
4c04137d 721 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
8e53a4fc
HSHR
722 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
723 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
724 */
10ca4f1c 725if (Ustrcmp(exp_curve, "auto") == 0)
038597d2 726 {
8e53a4fc 727#if OPENSSL_VERSION_NUMBER < 0x10002000L
10ca4f1c 728 DEBUG(D_tls) debug_printf(
8e53a4fc
HSHR
729 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
730 exp_curve = "prime256v1";
731#else
732# if defined SSL_CTRL_SET_ECDH_AUTO
733 DEBUG(D_tls) debug_printf(
734 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
10ca4f1c
JH
735 SSL_CTX_set_ecdh_auto(sctx, 1);
736 return TRUE;
8e53a4fc
HSHR
737# else
738 DEBUG(D_tls) debug_printf(
739 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
740 return TRUE;
741# endif
742#endif
10ca4f1c 743 }
038597d2 744
10ca4f1c
JH
745DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
746if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
747# ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
748 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
749# endif
750 )
751 {
cf0c6164
JH
752 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
753 host, NULL, errstr);
10ca4f1c
JH
754 return FALSE;
755 }
038597d2 756
10ca4f1c
JH
757if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
758 {
cf0c6164 759 tls_error(US"Unable to create ec curve", host, NULL, errstr);
10ca4f1c 760 return FALSE;
038597d2 761 }
10ca4f1c
JH
762
763/* The "tmp" in the name here refers to setting a temporary key
764not to the stability of the interface. */
765
766if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
cf0c6164 767 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
10ca4f1c
JH
768else
769 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
770
771EC_KEY_free(ecdh);
772return !rv;
773
774# endif /*EXIM_HAVE_ECDH*/
775#endif /*OPENSSL_NO_ECDH*/
038597d2
PP
776}
777
778
779
780
f2de3a33 781#ifndef DISABLE_OCSP
3f7eeb86
PP
782/*************************************************
783* Load OCSP information into state *
784*************************************************/
f5d78688 785/* Called to load the server OCSP response from the given file into memory, once
3f7eeb86
PP
786caller has determined this is needed. Checks validity. Debugs a message
787if invalid.
788
789ASSUMES: single response, for single cert.
790
791Arguments:
792 sctx the SSL_CTX* to update
793 cbinfo various parts of session state
794 expanded the filename putatively holding an OCSP response
795
796*/
797
798static void
f5d78688 799ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
3f7eeb86 800{
ee5b1e28
JH
801BIO * bio;
802OCSP_RESPONSE * resp;
803OCSP_BASICRESP * basic_response;
804OCSP_SINGLERESP * single_response;
805ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
ee5b1e28 806STACK_OF(X509) * sk;
3f7eeb86
PP
807unsigned long verify_flags;
808int status, reason, i;
809
f5d78688
JH
810cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
811if (cbinfo->u_ocsp.server.response)
3f7eeb86 812 {
f5d78688
JH
813 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
814 cbinfo->u_ocsp.server.response = NULL;
3f7eeb86
PP
815 }
816
ee5b1e28 817if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
3f7eeb86
PP
818 {
819 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
f5d78688 820 cbinfo->u_ocsp.server.file_expanded);
3f7eeb86
PP
821 return;
822 }
823
824resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
825BIO_free(bio);
826if (!resp)
827 {
828 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
829 return;
830 }
831
ee5b1e28 832if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
3f7eeb86
PP
833 {
834 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
835 OCSP_response_status_str(status), status);
f5d78688 836 goto bad;
3f7eeb86
PP
837 }
838
ee5b1e28 839if (!(basic_response = OCSP_response_get1_basic(resp)))
3f7eeb86
PP
840 {
841 DEBUG(D_tls)
842 debug_printf("OCSP response parse error: unable to extract basic response.\n");
f5d78688 843 goto bad;
3f7eeb86
PP
844 }
845
c3033f13 846sk = cbinfo->verify_stack;
3f7eeb86
PP
847verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
848
849/* May need to expose ability to adjust those flags?
850OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
851OCSP_TRUSTOTHER OCSP_NOINTERN */
852
4c04137d 853/* This does a full verify on the OCSP proof before we load it for serving
ee5b1e28
JH
854up; possibly overkill - just date-checks might be nice enough.
855
856OCSP_basic_verify takes a "store" arg, but does not
857use it for the chain verification, which is all we do
858when OCSP_NOVERIFY is set. The content from the wire
859"basic_response" and a cert-stack "sk" are all that is used.
860
c3033f13
JH
861We have a stack, loaded in setup_certs() if tls_verify_certificates
862was a file (not a directory, or "system"). It is unfortunate we
863cannot used the connection context store, as that would neatly
864handle the "system" case too, but there seems to be no library
865function for getting a stack from a store.
e3555426 866[ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
c3033f13
JH
867We do not free the stack since it could be needed a second time for
868SNI handling.
869
4c04137d 870Separately we might try to replace using OCSP_basic_verify() - which seems to not
ee5b1e28
JH
871be a public interface into the OpenSSL library (there's no manual entry) -
872But what with? We also use OCSP_basic_verify in the client stapling callback.
4c04137d 873And there we NEED it; we must verify that status... unless the
ee5b1e28
JH
874library does it for us anyway? */
875
876if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
3f7eeb86 877 {
ee5b1e28
JH
878 DEBUG(D_tls)
879 {
3f7eeb86
PP
880 ERR_error_string(ERR_get_error(), ssl_errstring);
881 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
f5d78688
JH
882 }
883 goto bad;
3f7eeb86
PP
884 }
885
886/* Here's the simplifying assumption: there's only one response, for the
887one certificate we use, and nothing for anything else in a chain. If this
888proves false, we need to extract a cert id from our issued cert
889(tls_certificate) and use that for OCSP_resp_find_status() (which finds the
890right cert in the stack and then calls OCSP_single_get0_status()).
891
892I'm hoping to avoid reworking a bunch more of how we handle state here. */
ee5b1e28
JH
893
894if (!(single_response = OCSP_resp_get0(basic_response, 0)))
3f7eeb86
PP
895 {
896 DEBUG(D_tls)
897 debug_printf("Unable to get first response from OCSP basic response.\n");
f5d78688 898 goto bad;
3f7eeb86
PP
899 }
900
901status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
f5d78688 902if (status != V_OCSP_CERTSTATUS_GOOD)
3f7eeb86 903 {
f5d78688
JH
904 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
905 OCSP_cert_status_str(status), status,
906 OCSP_crl_reason_str(reason), reason);
907 goto bad;
3f7eeb86
PP
908 }
909
910if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
911 {
912 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
f5d78688 913 goto bad;
3f7eeb86
PP
914 }
915
f5d78688 916supply_response:
018058b2 917 cbinfo->u_ocsp.server.response = resp;
f5d78688
JH
918return;
919
920bad:
018058b2
JH
921 if (running_in_test_harness)
922 {
923 extern char ** environ;
924 uschar ** p;
bc3c7bb7 925 if (environ) for (p = USS environ; *p != NULL; p++)
018058b2
JH
926 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
927 {
928 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
929 goto supply_response;
930 }
931 }
f5d78688 932return;
3f7eeb86 933}
f2de3a33 934#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
935
936
937
938
23bb6982
JH
939/* Create and install a selfsigned certificate, for use in server mode */
940
941static int
cf0c6164 942tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
23bb6982
JH
943{
944X509 * x509 = NULL;
945EVP_PKEY * pkey;
946RSA * rsa;
947X509_NAME * name;
948uschar * where;
949
950where = US"allocating pkey";
951if (!(pkey = EVP_PKEY_new()))
952 goto err;
953
954where = US"allocating cert";
955if (!(x509 = X509_new()))
956 goto err;
957
958where = US"generating pkey";
959 /* deprecated, use RSA_generate_key_ex() */
960if (!(rsa = RSA_generate_key(1024, RSA_F4, NULL, NULL)))
961 goto err;
962
4c04137d 963where = US"assigning pkey";
23bb6982
JH
964if (!EVP_PKEY_assign_RSA(pkey, rsa))
965 goto err;
966
967X509_set_version(x509, 2); /* N+1 - version 3 */
968ASN1_INTEGER_set(X509_get_serialNumber(x509), 0);
969X509_gmtime_adj(X509_get_notBefore(x509), 0);
970X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
971X509_set_pubkey(x509, pkey);
972
973name = X509_get_subject_name(x509);
974X509_NAME_add_entry_by_txt(name, "C",
4dc2379a 975 MBSTRING_ASC, CUS "UK", -1, -1, 0);
23bb6982 976X509_NAME_add_entry_by_txt(name, "O",
4dc2379a 977 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
23bb6982 978X509_NAME_add_entry_by_txt(name, "CN",
4dc2379a 979 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
23bb6982
JH
980X509_set_issuer_name(x509, name);
981
982where = US"signing cert";
983if (!X509_sign(x509, pkey, EVP_md5()))
984 goto err;
985
986where = US"installing selfsign cert";
987if (!SSL_CTX_use_certificate(sctx, x509))
988 goto err;
989
990where = US"installing selfsign key";
991if (!SSL_CTX_use_PrivateKey(sctx, pkey))
992 goto err;
993
994return OK;
995
996err:
cf0c6164 997 (void) tls_error(where, NULL, NULL, errstr);
23bb6982
JH
998 if (x509) X509_free(x509);
999 if (pkey) EVP_PKEY_free(pkey);
1000 return DEFER;
1001}
1002
1003
1004
1005
059ec3d9 1006/*************************************************
7be682ca
PP
1007* Expand key and cert file specs *
1008*************************************************/
1009
f5d78688 1010/* Called once during tls_init and possibly again during TLS setup, for a
7be682ca
PP
1011new context, if Server Name Indication was used and tls_sni was seen in
1012the certificate string.
1013
1014Arguments:
1015 sctx the SSL_CTX* to update
1016 cbinfo various parts of session state
cf0c6164 1017 errstr error string pointer
7be682ca
PP
1018
1019Returns: OK/DEFER/FAIL
1020*/
1021
1022static int
cf0c6164
JH
1023tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1024 uschar ** errstr)
7be682ca
PP
1025{
1026uschar *expanded;
1027
23bb6982 1028if (!cbinfo->certificate)
7be682ca 1029 {
23bb6982
JH
1030 if (cbinfo->host) /* client */
1031 return OK;
1032 /* server */
cf0c6164 1033 if (tls_install_selfsign(sctx, errstr) != OK)
23bb6982 1034 return DEFER;
7be682ca 1035 }
23bb6982
JH
1036else
1037 {
1038 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1039 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1040 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1041 )
1042 reexpand_tls_files_for_sni = TRUE;
7be682ca 1043
cf0c6164 1044 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
23bb6982
JH
1045 return DEFER;
1046
1047 if (expanded != NULL)
1048 {
1049 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
1050 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
1051 return tls_error(string_sprintf(
1052 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
cf0c6164 1053 cbinfo->host, NULL, errstr);
23bb6982 1054 }
7be682ca 1055
23bb6982 1056 if (cbinfo->privatekey != NULL &&
cf0c6164 1057 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
23bb6982 1058 return DEFER;
7be682ca 1059
23bb6982
JH
1060 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1061 of the expansion is an empty string, ignore it also, and assume the private
1062 key is in the same file as the certificate. */
1063
1064 if (expanded && *expanded)
1065 {
1066 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
1067 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
1068 return tls_error(string_sprintf(
cf0c6164 1069 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL, errstr);
23bb6982 1070 }
7be682ca
PP
1071 }
1072
f2de3a33 1073#ifndef DISABLE_OCSP
f40d5be3 1074if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
3f7eeb86 1075 {
cf0c6164 1076 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
3f7eeb86
PP
1077 return DEFER;
1078
f40d5be3 1079 if (expanded && *expanded)
3f7eeb86
PP
1080 {
1081 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
f40d5be3
JH
1082 if ( cbinfo->u_ocsp.server.file_expanded
1083 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
3f7eeb86 1084 {
f40d5be3
JH
1085 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1086 }
1087 else
f40d5be3 1088 ocsp_load_response(sctx, cbinfo, expanded);
3f7eeb86
PP
1089 }
1090 }
1091#endif
1092
7be682ca
PP
1093return OK;
1094}
1095
1096
1097
1098
1099/*************************************************
1100* Callback to handle SNI *
1101*************************************************/
1102
1103/* Called when acting as server during the TLS session setup if a Server Name
1104Indication extension was sent by the client.
1105
1106API documentation is OpenSSL s_server.c implementation.
1107
1108Arguments:
1109 s SSL* of the current session
1110 ad unknown (part of OpenSSL API) (unused)
1111 arg Callback of "our" registered data
1112
1113Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1114*/
1115
3bcbbbe2 1116#ifdef EXIM_HAVE_OPENSSL_TLSEXT
7be682ca 1117static int
7be682ca
PP
1118tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1119{
1120const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
3f7eeb86 1121tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
7be682ca 1122int rc;
3f0945ff 1123int old_pool = store_pool;
cf0c6164 1124uschar * dummy_errstr;
7be682ca
PP
1125
1126if (!servername)
1127 return SSL_TLSEXT_ERR_OK;
1128
3f0945ff 1129DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
7be682ca
PP
1130 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1131
1132/* Make the extension value available for expansion */
3f0945ff 1133store_pool = POOL_PERM;
817d9f57 1134tls_in.sni = string_copy(US servername);
3f0945ff 1135store_pool = old_pool;
7be682ca
PP
1136
1137if (!reexpand_tls_files_for_sni)
1138 return SSL_TLSEXT_ERR_OK;
1139
1140/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1141not confident that memcpy wouldn't break some internal reference counting.
1142Especially since there's a references struct member, which would be off. */
1143
0df4ab80 1144if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
7be682ca
PP
1145 {
1146 ERR_error_string(ERR_get_error(), ssl_errstring);
1147 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1148 return SSL_TLSEXT_ERR_NOACK;
1149 }
1150
1151/* Not sure how many of these are actually needed, since SSL object
1152already exists. Might even need this selfsame callback, for reneg? */
1153
817d9f57
JH
1154SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1155SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1156SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1157SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1158SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1159SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
038597d2 1160
cf0c6164
JH
1161if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1162 || !init_ecdh(server_sni, NULL, &dummy_errstr)
038597d2
PP
1163 )
1164 return SSL_TLSEXT_ERR_NOACK;
1165
7be682ca 1166if (cbinfo->server_cipher_list)
817d9f57 1167 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
f2de3a33 1168#ifndef DISABLE_OCSP
f5d78688 1169if (cbinfo->u_ocsp.server.file)
3f7eeb86 1170 {
f5d78688 1171 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
14c7b357 1172 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
3f7eeb86
PP
1173 }
1174#endif
7be682ca 1175
c3033f13 1176if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
cf0c6164 1177 verify_callback_server, &dummy_errstr)) != OK)
c3033f13 1178 return SSL_TLSEXT_ERR_NOACK;
7be682ca 1179
3f7eeb86
PP
1180/* do this after setup_certs, because this can require the certs for verifying
1181OCSP information. */
cf0c6164 1182if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
0df4ab80 1183 return SSL_TLSEXT_ERR_NOACK;
a799883d 1184
7be682ca 1185DEBUG(D_tls) debug_printf("Switching SSL context.\n");
817d9f57 1186SSL_set_SSL_CTX(s, server_sni);
7be682ca
PP
1187
1188return SSL_TLSEXT_ERR_OK;
1189}
3bcbbbe2 1190#endif /* EXIM_HAVE_OPENSSL_TLSEXT */
7be682ca
PP
1191
1192
1193
1194
f2de3a33 1195#ifndef DISABLE_OCSP
f5d78688 1196
3f7eeb86
PP
1197/*************************************************
1198* Callback to handle OCSP Stapling *
1199*************************************************/
1200
1201/* Called when acting as server during the TLS session setup if the client
1202requests OCSP information with a Certificate Status Request.
1203
1204Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1205project.
1206
1207*/
1208
1209static int
f5d78688 1210tls_server_stapling_cb(SSL *s, void *arg)
3f7eeb86
PP
1211{
1212const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1213uschar *response_der;
1214int response_der_len;
1215
af4a1bca 1216DEBUG(D_tls)
b3ef41c9 1217 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
f5d78688
JH
1218 cbinfo->u_ocsp.server.response ? "have" : "lack");
1219
44662487 1220tls_in.ocsp = OCSP_NOT_RESP;
f5d78688 1221if (!cbinfo->u_ocsp.server.response)
3f7eeb86
PP
1222 return SSL_TLSEXT_ERR_NOACK;
1223
1224response_der = NULL;
44662487
JH
1225response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
1226 &response_der);
3f7eeb86
PP
1227if (response_der_len <= 0)
1228 return SSL_TLSEXT_ERR_NOACK;
1229
5e55c7a9 1230SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
44662487 1231tls_in.ocsp = OCSP_VFIED;
3f7eeb86
PP
1232return SSL_TLSEXT_ERR_OK;
1233}
1234
3f7eeb86 1235
f5d78688
JH
1236static void
1237time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1238{
1239BIO_printf(bp, "\t%s: ", str);
1240ASN1_GENERALIZEDTIME_print(bp, time);
1241BIO_puts(bp, "\n");
1242}
1243
1244static int
1245tls_client_stapling_cb(SSL *s, void *arg)
1246{
1247tls_ext_ctx_cb * cbinfo = arg;
1248const unsigned char * p;
1249int len;
1250OCSP_RESPONSE * rsp;
1251OCSP_BASICRESP * bs;
1252int i;
1253
1254DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1255len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1256if(!p)
1257 {
44662487 1258 /* Expect this when we requested ocsp but got none */
6c6d6e48 1259 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
44662487 1260 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
f5d78688
JH
1261 else
1262 DEBUG(D_tls) debug_printf(" null\n");
44662487 1263 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688 1264 }
018058b2 1265
f5d78688
JH
1266if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1267 {
018058b2 1268 tls_out.ocsp = OCSP_FAILED;
6c6d6e48 1269 if (LOGGING(tls_cipher))
1eca31ca 1270 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
f5d78688
JH
1271 else
1272 DEBUG(D_tls) debug_printf(" parse error\n");
1273 return 0;
1274 }
1275
1276if(!(bs = OCSP_response_get1_basic(rsp)))
1277 {
018058b2 1278 tls_out.ocsp = OCSP_FAILED;
6c6d6e48 1279 if (LOGGING(tls_cipher))
1eca31ca 1280 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
f5d78688
JH
1281 else
1282 DEBUG(D_tls) debug_printf(" error parsing response\n");
1283 OCSP_RESPONSE_free(rsp);
1284 return 0;
1285 }
1286
1287/* We'd check the nonce here if we'd put one in the request. */
1288/* However that would defeat cacheability on the server so we don't. */
1289
f5d78688
JH
1290/* This section of code reworked from OpenSSL apps source;
1291 The OpenSSL Project retains copyright:
1292 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1293*/
1294 {
1295 BIO * bp = NULL;
f5d78688
JH
1296 int status, reason;
1297 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1298
1299 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1300
1301 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1302
1303 /* Use the chain that verified the server cert to verify the stapled info */
1304 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1305
c3033f13 1306 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
44662487 1307 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
f5d78688 1308 {
018058b2 1309 tls_out.ocsp = OCSP_FAILED;
6c6d6e48 1310 if (LOGGING(tls_cipher))
1eca31ca 1311 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
f5d78688
JH
1312 BIO_printf(bp, "OCSP response verify failure\n");
1313 ERR_print_errors(bp);
c8dfb21d 1314 goto failed;
f5d78688
JH
1315 }
1316
1317 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1318
c8dfb21d
JH
1319 /*XXX So we have a good stapled OCSP status. How do we know
1320 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1321 OCSP_resp_find_status() which matches on a cert id, which presumably
1322 we should use. Making an id needs OCSP_cert_id_new(), which takes
1323 issuerName, issuerKey, serialNumber. Are they all in the cert?
1324
1325 For now, carry on blindly accepting the resp. */
1326
f5d78688 1327 {
f5d78688
JH
1328 OCSP_SINGLERESP * single;
1329
c8dfb21d
JH
1330#ifdef EXIM_HAVE_OCSP_RESP_COUNT
1331 if (OCSP_resp_count(bs) != 1)
1332#else
1333 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
f5d78688 1334 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
c8dfb21d 1335#endif
f5d78688 1336 {
018058b2 1337 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1338 log_write(0, LOG_MAIN, "OCSP stapling "
1339 "with multiple responses not handled");
c8dfb21d 1340 goto failed;
f5d78688
JH
1341 }
1342 single = OCSP_resp_get0(bs, 0);
44662487
JH
1343 status = OCSP_single_get0_status(single, &reason, &rev,
1344 &thisupd, &nextupd);
f5d78688
JH
1345 }
1346
f5d78688
JH
1347 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1348 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
44662487
JH
1349 if (!OCSP_check_validity(thisupd, nextupd,
1350 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
f5d78688 1351 {
018058b2 1352 tls_out.ocsp = OCSP_FAILED;
f5d78688
JH
1353 DEBUG(D_tls) ERR_print_errors(bp);
1354 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
f5d78688 1355 }
44662487 1356 else
f5d78688 1357 {
44662487
JH
1358 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1359 OCSP_cert_status_str(status));
1360 switch(status)
1361 {
1362 case V_OCSP_CERTSTATUS_GOOD:
44662487 1363 tls_out.ocsp = OCSP_VFIED;
018058b2 1364 i = 1;
c8dfb21d 1365 goto good;
44662487 1366 case V_OCSP_CERTSTATUS_REVOKED:
018058b2 1367 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1368 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1369 reason != -1 ? "; reason: " : "",
1370 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1371 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
44662487
JH
1372 break;
1373 default:
018058b2 1374 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1375 log_write(0, LOG_MAIN,
1376 "Server certificate status unknown, in OCSP stapling");
44662487
JH
1377 break;
1378 }
f5d78688 1379 }
c8dfb21d
JH
1380 failed:
1381 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1382 good:
f5d78688
JH
1383 BIO_free(bp);
1384 }
1385
1386OCSP_RESPONSE_free(rsp);
1387return i;
1388}
f2de3a33 1389#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
1390
1391
7be682ca 1392/*************************************************
059ec3d9
PH
1393* Initialize for TLS *
1394*************************************************/
1395
e51c7be2
JH
1396/* Called from both server and client code, to do preliminary initialization
1397of the library. We allocate and return a context structure.
059ec3d9
PH
1398
1399Arguments:
946ecbe0 1400 ctxp returned SSL context
059ec3d9
PH
1401 host connected host, if client; NULL if server
1402 dhparam DH parameter file
1403 certificate certificate file
1404 privatekey private key
f5d78688 1405 ocsp_file file of stapling info (server); flag for require ocsp (client)
059ec3d9 1406 addr address if client; NULL if server (for some randomness)
946ecbe0 1407 cbp place to put allocated callback context
cf0c6164 1408 errstr error string pointer
059ec3d9
PH
1409
1410Returns: OK/DEFER/FAIL
1411*/
1412
1413static int
817d9f57 1414tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
3f7eeb86 1415 uschar *privatekey,
f2de3a33 1416#ifndef DISABLE_OCSP
3f7eeb86
PP
1417 uschar *ocsp_file,
1418#endif
cf0c6164 1419 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
059ec3d9 1420{
77bb000f 1421long init_options;
7be682ca 1422int rc;
77bb000f 1423BOOL okay;
a7538db1 1424tls_ext_ctx_cb * cbinfo;
7be682ca
PP
1425
1426cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1427cbinfo->certificate = certificate;
1428cbinfo->privatekey = privatekey;
f2de3a33 1429#ifndef DISABLE_OCSP
c3033f13 1430cbinfo->verify_stack = NULL;
f5d78688
JH
1431if ((cbinfo->is_server = host==NULL))
1432 {
1433 cbinfo->u_ocsp.server.file = ocsp_file;
1434 cbinfo->u_ocsp.server.file_expanded = NULL;
1435 cbinfo->u_ocsp.server.response = NULL;
1436 }
1437else
1438 cbinfo->u_ocsp.client.verify_store = NULL;
3f7eeb86 1439#endif
7be682ca 1440cbinfo->dhparam = dhparam;
0df4ab80 1441cbinfo->server_cipher_list = NULL;
7be682ca 1442cbinfo->host = host;
0cbf2b82 1443#ifndef DISABLE_EVENT
a7538db1
JH
1444cbinfo->event_action = NULL;
1445#endif
77bb000f 1446
059ec3d9
PH
1447SSL_load_error_strings(); /* basic set up */
1448OpenSSL_add_ssl_algorithms();
1449
c8dfb21d 1450#ifdef EXIM_HAVE_SHA256
77bb000f 1451/* SHA256 is becoming ever more popular. This makes sure it gets added to the
a0475b69
TK
1452list of available digests. */
1453EVP_add_digest(EVP_sha256());
cf1ef1a9 1454#endif
a0475b69 1455
f0f5a555
PP
1456/* Create a context.
1457The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1458negotiation in the different methods; as far as I can tell, the only
1459*_{server,client}_method which allows negotiation is SSLv23, which exists even
1460when OpenSSL is built without SSLv2 support.
1461By disabling with openssl_options, we can let admins re-enable with the
1462existing knob. */
059ec3d9 1463
c8dfb21d 1464*ctxp = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method());
059ec3d9 1465
cf0c6164 1466if (!*ctxp) return tls_error(US"SSL_CTX_new", host, NULL, errstr);
059ec3d9
PH
1467
1468/* It turns out that we need to seed the random number generator this early in
1469order to get the full complement of ciphers to work. It took me roughly a day
1470of work to discover this by experiment.
1471
1472On systems that have /dev/urandom, SSL may automatically seed itself from
1473there. Otherwise, we have to make something up as best we can. Double check
1474afterwards. */
1475
1476if (!RAND_status())
1477 {
1478 randstuff r;
9e3331ea 1479 gettimeofday(&r.tv, NULL);
059ec3d9
PH
1480 r.p = getpid();
1481
1482 RAND_seed((uschar *)(&r), sizeof(r));
1483 RAND_seed((uschar *)big_buffer, big_buffer_size);
1484 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1485
1486 if (!RAND_status())
7199e1ee 1487 return tls_error(US"RAND_status", host,
cf0c6164 1488 US"unable to seed random number generator", errstr);
059ec3d9
PH
1489 }
1490
1491/* Set up the information callback, which outputs if debugging is at a suitable
1492level. */
1493
f69979cf 1494DEBUG(D_tls) SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
059ec3d9 1495
c80c5570 1496/* Automatically re-try reads/writes after renegotiation. */
817d9f57 1497(void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
c80c5570 1498
77bb000f
PP
1499/* Apply administrator-supplied work-arounds.
1500Historically we applied just one requested option,
1501SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1502moved to an administrator-controlled list of options to specify and
1503grandfathered in the first one as the default value for "openssl_options".
059ec3d9 1504
77bb000f
PP
1505No OpenSSL version number checks: the options we accept depend upon the
1506availability of the option value macros from OpenSSL. */
059ec3d9 1507
77bb000f
PP
1508okay = tls_openssl_options_parse(openssl_options, &init_options);
1509if (!okay)
cf0c6164 1510 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
77bb000f
PP
1511
1512if (init_options)
1513 {
1514 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
817d9f57 1515 if (!(SSL_CTX_set_options(*ctxp, init_options)))
77bb000f 1516 return tls_error(string_sprintf(
cf0c6164 1517 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
77bb000f
PP
1518 }
1519else
1520 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
059ec3d9
PH
1521
1522/* Initialize with DH parameters if supplied */
10ca4f1c 1523/* Initialize ECDH temp key parameter selection */
059ec3d9 1524
cf0c6164
JH
1525if ( !init_dh(*ctxp, dhparam, host, errstr)
1526 || !init_ecdh(*ctxp, host, errstr)
038597d2
PP
1527 )
1528 return DEFER;
059ec3d9 1529
3f7eeb86 1530/* Set up certificate and key (and perhaps OCSP info) */
059ec3d9 1531
cf0c6164 1532if ((rc = tls_expand_session_files(*ctxp, cbinfo, errstr)) != OK)
23bb6982 1533 return rc;
c91535f3 1534
c3033f13
JH
1535/* If we need to handle SNI or OCSP, do so */
1536
3bcbbbe2 1537#ifdef EXIM_HAVE_OPENSSL_TLSEXT
c3033f13
JH
1538# ifndef DISABLE_OCSP
1539 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1540 {
1541 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1542 return FAIL;
1543 }
1544# endif
1545
f5d78688 1546if (host == NULL) /* server */
3f0945ff 1547 {
f2de3a33 1548# ifndef DISABLE_OCSP
f5d78688 1549 /* We check u_ocsp.server.file, not server.response, because we care about if
3f7eeb86
PP
1550 the option exists, not what the current expansion might be, as SNI might
1551 change the certificate and OCSP file in use between now and the time the
1552 callback is invoked. */
f5d78688 1553 if (cbinfo->u_ocsp.server.file)
3f7eeb86 1554 {
f5d78688 1555 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
5e55c7a9 1556 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
3f7eeb86 1557 }
f5d78688 1558# endif
3f0945ff
PP
1559 /* We always do this, so that $tls_sni is available even if not used in
1560 tls_certificate */
817d9f57
JH
1561 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1562 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
3f0945ff 1563 }
f2de3a33 1564# ifndef DISABLE_OCSP
f5d78688
JH
1565else /* client */
1566 if(ocsp_file) /* wanting stapling */
1567 {
1568 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1569 {
1570 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1571 return FAIL;
1572 }
1573 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1574 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1575 }
1576# endif
7be682ca 1577#endif
059ec3d9 1578
e51c7be2 1579cbinfo->verify_cert_hostnames = NULL;
e51c7be2 1580
c8dfb21d 1581#ifdef EXIM_HAVE_EPHEM_RSA_KEX
059ec3d9 1582/* Set up the RSA callback */
817d9f57 1583SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
c8dfb21d 1584#endif
059ec3d9
PH
1585
1586/* Finally, set the timeout, and we are done */
1587
817d9f57 1588SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
059ec3d9 1589DEBUG(D_tls) debug_printf("Initialized TLS\n");
7be682ca 1590
817d9f57 1591*cbp = cbinfo;
7be682ca 1592
059ec3d9
PH
1593return OK;
1594}
1595
1596
1597
1598
1599/*************************************************
1600* Get name of cipher in use *
1601*************************************************/
1602
817d9f57 1603/*
059ec3d9 1604Argument: pointer to an SSL structure for the connection
817d9f57
JH
1605 buffer to use for answer
1606 size of buffer
1607 pointer to number of bits for cipher
059ec3d9
PH
1608Returns: nothing
1609*/
1610
1611static void
817d9f57 1612construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
059ec3d9 1613{
57b3a7f5
PP
1614/* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1615yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1616the accessor functions use const in the prototype. */
1617const SSL_CIPHER *c;
d9784128 1618const uschar *ver;
059ec3d9 1619
d9784128 1620ver = (const uschar *)SSL_get_version(ssl);
059ec3d9 1621
57b3a7f5 1622c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1623SSL_CIPHER_get_bits(c, bits);
059ec3d9 1624
817d9f57
JH
1625string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1626 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1627
1628DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1629}
1630
1631
f69979cf
JH
1632static void
1633peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1634{
1635/*XXX we might consider a list-of-certs variable for the cert chain.
1636SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1637in list-handling functions, also consider the difference between the entire
1638chain and the elements sent by the peer. */
1639
1640/* Will have already noted peercert on a verify fail; possibly not the leaf */
1641if (!tlsp->peercert)
1642 tlsp->peercert = SSL_get_peer_certificate(ssl);
1643/* Beware anonymous ciphers which lead to server_cert being NULL */
1644if (tlsp->peercert)
1645 {
1646 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1647 peerdn[bsize-1] = '\0';
1648 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1649 }
1650else
1651 tlsp->peerdn = NULL;
1652}
1653
1654
059ec3d9
PH
1655
1656
1657
1658/*************************************************
1659* Set up for verifying certificates *
1660*************************************************/
1661
c3033f13
JH
1662/* Load certs from file, return TRUE on success */
1663
1664static BOOL
1665chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1666{
1667BIO * bp;
1668X509 * x;
1669
1670if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1671while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1672 sk_X509_push(verify_stack, x);
1673BIO_free(bp);
1674return TRUE;
1675}
1676
1677
1678
059ec3d9
PH
1679/* Called by both client and server startup
1680
1681Arguments:
7be682ca 1682 sctx SSL_CTX* to initialise
059ec3d9
PH
1683 certs certs file or NULL
1684 crl CRL file or NULL
1685 host NULL in a server; the remote host in a client
1686 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1687 otherwise passed as FALSE
983207c1 1688 cert_vfy_cb Callback function for certificate verification
cf0c6164 1689 errstr error string pointer
059ec3d9
PH
1690
1691Returns: OK/DEFER/FAIL
1692*/
1693
1694static int
983207c1 1695setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
cf0c6164 1696 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
059ec3d9
PH
1697{
1698uschar *expcerts, *expcrl;
1699
cf0c6164 1700if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
059ec3d9 1701 return DEFER;
57cc2785 1702DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
059ec3d9 1703
10a831a3 1704if (expcerts && *expcerts)
059ec3d9 1705 {
10a831a3
JH
1706 /* Tell the library to use its compiled-in location for the system default
1707 CA bundle. Then add the ones specified in the config, if any. */
cb1d7830 1708
10a831a3 1709 if (!SSL_CTX_set_default_verify_paths(sctx))
cf0c6164 1710 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
10a831a3
JH
1711
1712 if (Ustrcmp(expcerts, "system") != 0)
059ec3d9 1713 {
cb1d7830
JH
1714 struct stat statbuf;
1715
cb1d7830
JH
1716 if (Ustat(expcerts, &statbuf) < 0)
1717 {
1718 log_write(0, LOG_MAIN|LOG_PANIC,
1719 "failed to stat %s for certificates", expcerts);
1720 return DEFER;
1721 }
059ec3d9 1722 else
059ec3d9 1723 {
cb1d7830
JH
1724 uschar *file, *dir;
1725 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1726 { file = NULL; dir = expcerts; }
1727 else
c3033f13
JH
1728 {
1729 file = expcerts; dir = NULL;
1730#ifndef DISABLE_OCSP
1731 /* In the server if we will be offering an OCSP proof, load chain from
1732 file for verifying the OCSP proof at load time. */
1733
1734 if ( !host
1735 && statbuf.st_size > 0
1736 && server_static_cbinfo->u_ocsp.server.file
1737 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
1738 )
1739 {
1740 log_write(0, LOG_MAIN|LOG_PANIC,
1741 "failed to load cert hain from %s", file);
1742 return DEFER;
1743 }
1744#endif
1745 }
cb1d7830
JH
1746
1747 /* If a certificate file is empty, the next function fails with an
1748 unhelpful error message. If we skip it, we get the correct behaviour (no
1749 certificates are recognized, but the error message is still misleading (it
c3033f13 1750 says no certificate was supplied). But this is better. */
cb1d7830 1751
f2f2c91b
JH
1752 if ( (!file || statbuf.st_size > 0)
1753 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
cf0c6164 1754 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
cb1d7830
JH
1755
1756 /* Load the list of CAs for which we will accept certs, for sending
1757 to the client. This is only for the one-file tls_verify_certificates
1758 variant.
1759 If a list isn't loaded into the server, but
1760 some verify locations are set, the server end appears to make
4c04137d 1761 a wildcard request for client certs.
10a831a3 1762 Meanwhile, the client library as default behaviour *ignores* the list
cb1d7830
JH
1763 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1764 Because of this, and that the dir variant is likely only used for
1765 the public-CA bundle (not for a private CA), not worth fixing.
1766 */
f2f2c91b 1767 if (file)
cb1d7830
JH
1768 {
1769 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
f2f2c91b
JH
1770
1771 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
cb1d7830
JH
1772 sk_X509_NAME_num(names));
1773 SSL_CTX_set_client_CA_list(sctx, names);
1774 }
059ec3d9
PH
1775 }
1776 }
1777
1778 /* Handle a certificate revocation list. */
1779
10a831a3 1780#if OPENSSL_VERSION_NUMBER > 0x00907000L
059ec3d9 1781
8b417f2c 1782 /* This bit of code is now the version supplied by Lars Mainka. (I have
10a831a3 1783 merely reformatted it into the Exim code style.)
8b417f2c 1784
10a831a3
JH
1785 "From here I changed the code to add support for multiple crl's
1786 in pem format in one file or to support hashed directory entries in
1787 pem format instead of a file. This method now uses the library function
1788 X509_STORE_load_locations to add the CRL location to the SSL context.
1789 OpenSSL will then handle the verify against CA certs and CRLs by
1790 itself in the verify callback." */
8b417f2c 1791
cf0c6164 1792 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
10a831a3 1793 if (expcrl && *expcrl)
059ec3d9 1794 {
8b417f2c
PH
1795 struct stat statbufcrl;
1796 if (Ustat(expcrl, &statbufcrl) < 0)
1797 {
1798 log_write(0, LOG_MAIN|LOG_PANIC,
1799 "failed to stat %s for certificates revocation lists", expcrl);
1800 return DEFER;
1801 }
1802 else
059ec3d9 1803 {
8b417f2c
PH
1804 /* is it a file or directory? */
1805 uschar *file, *dir;
7be682ca 1806 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1807 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1808 {
8b417f2c
PH
1809 file = NULL;
1810 dir = expcrl;
1811 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1812 }
1813 else
1814 {
8b417f2c
PH
1815 file = expcrl;
1816 dir = NULL;
1817 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1818 }
8b417f2c 1819 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
cf0c6164 1820 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
8b417f2c
PH
1821
1822 /* setting the flags to check against the complete crl chain */
1823
1824 X509_STORE_set_flags(cvstore,
1825 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1826 }
059ec3d9
PH
1827 }
1828
10a831a3 1829#endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
059ec3d9
PH
1830
1831 /* If verification is optional, don't fail if no certificate */
1832
7be682ca 1833 SSL_CTX_set_verify(sctx,
059ec3d9 1834 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1835 cert_vfy_cb);
059ec3d9
PH
1836 }
1837
1838return OK;
1839}
1840
1841
1842
1843/*************************************************
1844* Start a TLS session in a server *
1845*************************************************/
1846
1847/* This is called when Exim is running as a server, after having received
1848the STARTTLS command. It must respond to that command, and then negotiate
1849a TLS session.
1850
1851Arguments:
1852 require_ciphers allowed ciphers
cf0c6164 1853 errstr pointer to error message
059ec3d9
PH
1854
1855Returns: OK on success
1856 DEFER for errors before the start of the negotiation
4c04137d 1857 FAIL for errors during the negotiation; the server can't
059ec3d9
PH
1858 continue running.
1859*/
1860
1861int
cf0c6164 1862tls_server_start(const uschar * require_ciphers, uschar ** errstr)
059ec3d9
PH
1863{
1864int rc;
cf0c6164
JH
1865uschar * expciphers;
1866tls_ext_ctx_cb * cbinfo;
f69979cf 1867static uschar peerdn[256];
817d9f57 1868static uschar cipherbuf[256];
059ec3d9
PH
1869
1870/* Check for previous activation */
1871
817d9f57 1872if (tls_in.active >= 0)
059ec3d9 1873 {
cf0c6164 1874 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
059ec3d9
PH
1875 smtp_printf("554 Already in TLS\r\n");
1876 return FAIL;
1877 }
1878
1879/* Initialize the SSL library. If it fails, it will already have logged
1880the error. */
1881
817d9f57 1882rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
f2de3a33 1883#ifndef DISABLE_OCSP
3f7eeb86
PP
1884 tls_ocsp_file,
1885#endif
cf0c6164 1886 NULL, &server_static_cbinfo, errstr);
059ec3d9 1887if (rc != OK) return rc;
817d9f57 1888cbinfo = server_static_cbinfo;
059ec3d9 1889
cf0c6164 1890if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
059ec3d9
PH
1891 return FAIL;
1892
1893/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1894were historically separated by underscores. So that I can use either form in my
1895tests, and also for general convenience, we turn underscores into hyphens here.
1896*/
059ec3d9 1897
c3033f13 1898if (expciphers)
059ec3d9 1899 {
c3033f13 1900 uschar * s = expciphers;
059ec3d9
PH
1901 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1902 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1903 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
cf0c6164 1904 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
7be682ca 1905 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1906 }
1907
1908/* If this is a host for which certificate verification is mandatory or
1909optional, set up appropriately. */
1910
817d9f57 1911tls_in.certificate_verified = FALSE;
53a7196b
JH
1912#ifdef EXPERIMENTAL_DANE
1913tls_in.dane_verified = FALSE;
1914#endif
a2ff477a 1915server_verify_callback_called = FALSE;
059ec3d9
PH
1916
1917if (verify_check_host(&tls_verify_hosts) == OK)
1918 {
983207c1 1919 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
cf0c6164 1920 FALSE, verify_callback_server, errstr);
059ec3d9 1921 if (rc != OK) return rc;
a2ff477a 1922 server_verify_optional = FALSE;
059ec3d9
PH
1923 }
1924else if (verify_check_host(&tls_try_verify_hosts) == OK)
1925 {
983207c1 1926 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
cf0c6164 1927 TRUE, verify_callback_server, errstr);
059ec3d9 1928 if (rc != OK) return rc;
a2ff477a 1929 server_verify_optional = TRUE;
059ec3d9
PH
1930 }
1931
1932/* Prepare for new connection */
1933
cf0c6164
JH
1934if (!(server_ssl = SSL_new(server_ctx)))
1935 return tls_error(US"SSL_new", NULL, NULL, errstr);
da3ad30d
PP
1936
1937/* Warning: we used to SSL_clear(ssl) here, it was removed.
1938 *
1939 * With the SSL_clear(), we get strange interoperability bugs with
1940 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1941 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1942 *
1943 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1944 * session shutdown. In this case, we have a brand new object and there's no
1945 * obvious reason to immediately clear it. I'm guessing that this was
1946 * originally added because of incomplete initialisation which the clear fixed,
1947 * in some historic release.
1948 */
059ec3d9
PH
1949
1950/* Set context and tell client to go ahead, except in the case of TLS startup
1951on connection, where outputting anything now upsets the clients and tends to
1952make them disconnect. We need to have an explicit fflush() here, to force out
1953the response. Other smtp_printf() calls do not need it, because in non-TLS
1954mode, the fflush() happens when smtp_getc() is called. */
1955
817d9f57
JH
1956SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1957if (!tls_in.on_connect)
059ec3d9
PH
1958 {
1959 smtp_printf("220 TLS go ahead\r\n");
1960 fflush(smtp_out);
1961 }
1962
1963/* Now negotiate the TLS session. We put our own timer on it, since it seems
1964that the OpenSSL library doesn't. */
1965
817d9f57
JH
1966SSL_set_wfd(server_ssl, fileno(smtp_out));
1967SSL_set_rfd(server_ssl, fileno(smtp_in));
1968SSL_set_accept_state(server_ssl);
059ec3d9
PH
1969
1970DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1971
1972sigalrm_seen = FALSE;
1973if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 1974rc = SSL_accept(server_ssl);
059ec3d9
PH
1975alarm(0);
1976
1977if (rc <= 0)
1978 {
cf0c6164 1979 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
059ec3d9
PH
1980 return FAIL;
1981 }
1982
1983DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1984
1985/* TLS has been set up. Adjust the input functions to read via TLS,
1986and initialize things. */
1987
f69979cf
JH
1988peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
1989
817d9f57
JH
1990construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1991tls_in.cipher = cipherbuf;
059ec3d9
PH
1992
1993DEBUG(D_tls)
1994 {
1995 uschar buf[2048];
817d9f57 1996 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
1997 debug_printf("Shared ciphers: %s\n", buf);
1998 }
1999
9d1c15ef
JH
2000/* Record the certificate we presented */
2001 {
2002 X509 * crt = SSL_get_certificate(server_ssl);
2003 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2004 }
059ec3d9 2005
817d9f57
JH
2006/* Only used by the server-side tls (tls_in), including tls_getc.
2007 Client-side (tls_out) reads (seem to?) go via
2008 smtp_read_response()/ip_recv().
2009 Hence no need to duplicate for _in and _out.
2010 */
059ec3d9
PH
2011ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2012ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2013ssl_xfer_eof = ssl_xfer_error = 0;
2014
2015receive_getc = tls_getc;
584e96c6 2016receive_get_cache = tls_get_cache;
059ec3d9
PH
2017receive_ungetc = tls_ungetc;
2018receive_feof = tls_feof;
2019receive_ferror = tls_ferror;
58eb016e 2020receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 2021
817d9f57 2022tls_in.active = fileno(smtp_out);
059ec3d9
PH
2023return OK;
2024}
2025
2026
2027
2028
043b1248
JH
2029static int
2030tls_client_basic_ctx_init(SSL_CTX * ctx,
cf0c6164
JH
2031 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2032 uschar ** errstr)
043b1248
JH
2033{
2034int rc;
94431adb 2035/* stick to the old behaviour for compatibility if tls_verify_certificates is
043b1248
JH
2036 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2037 the specified host patterns if one of them is defined */
2038
610ff438
JH
2039if ( ( !ob->tls_verify_hosts
2040 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2041 )
5130845b 2042 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
aa2a70ba 2043 )
043b1248 2044 client_verify_optional = FALSE;
5130845b 2045else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
aa2a70ba
JH
2046 client_verify_optional = TRUE;
2047else
2048 return OK;
2049
2050if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
cf0c6164
JH
2051 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2052 errstr)) != OK)
aa2a70ba 2053 return rc;
043b1248 2054
5130845b 2055if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
043b1248 2056 {
4af0d74a 2057 cbinfo->verify_cert_hostnames =
8c5d388a 2058#ifdef SUPPORT_I18N
4af0d74a
JH
2059 string_domain_utf8_to_alabel(host->name, NULL);
2060#else
2061 host->name;
2062#endif
aa2a70ba
JH
2063 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2064 cbinfo->verify_cert_hostnames);
043b1248 2065 }
043b1248
JH
2066return OK;
2067}
059ec3d9 2068
fde080a4
JH
2069
2070#ifdef EXPERIMENTAL_DANE
2071static int
cf0c6164 2072dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
fde080a4
JH
2073{
2074dns_record * rr;
2075dns_scan dnss;
2076const char * hostnames[2] = { CS host->name, NULL };
2077int found = 0;
2078
2079if (DANESSL_init(ssl, NULL, hostnames) != 1)
cf0c6164 2080 return tls_error(US"hostnames load", host, NULL, errstr);
fde080a4
JH
2081
2082for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2083 rr;
2084 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2085 ) if (rr->type == T_TLSA)
2086 {
c3033f13 2087 const uschar * p = rr->data;
fde080a4
JH
2088 uint8_t usage, selector, mtype;
2089 const char * mdname;
2090
fde080a4 2091 usage = *p++;
133d2546
JH
2092
2093 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2094 if (usage != 2 && usage != 3) continue;
2095
fde080a4
JH
2096 selector = *p++;
2097 mtype = *p++;
2098
2099 switch (mtype)
2100 {
133d2546
JH
2101 default: continue; /* Only match-types 0, 1, 2 are supported */
2102 case 0: mdname = NULL; break;
2103 case 1: mdname = "sha256"; break;
2104 case 2: mdname = "sha512"; break;
fde080a4
JH
2105 }
2106
133d2546 2107 found++;
fde080a4
JH
2108 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2109 {
2110 default:
cf0c6164 2111 return tls_error(US"tlsa load", host, NULL, errstr);
c035b645 2112 case 0: /* action not taken */
fde080a4
JH
2113 case 1: break;
2114 }
594706ea
JH
2115
2116 tls_out.tlsa_usage |= 1<<usage;
fde080a4
JH
2117 }
2118
2119if (found)
2120 return OK;
2121
133d2546 2122log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
6ebd79ec 2123return DEFER;
fde080a4
JH
2124}
2125#endif /*EXPERIMENTAL_DANE*/
2126
2127
2128
059ec3d9
PH
2129/*************************************************
2130* Start a TLS session in a client *
2131*************************************************/
2132
2133/* Called from the smtp transport after STARTTLS has been accepted.
2134
2135Argument:
2136 fd the fd of the connection
2137 host connected host (for messages)
83da1223 2138 addr the first address
a7538db1 2139 tb transport (always smtp)
0e66b3b6 2140 tlsa_dnsa tlsa lookup, if DANE, else null
cf0c6164 2141 errstr error string pointer
059ec3d9
PH
2142
2143Returns: OK on success
2144 FAIL otherwise - note that tls_error() will not give DEFER
2145 because this is not a server
2146*/
2147
2148int
f5d78688 2149tls_client_start(int fd, host_item *host, address_item *addr,
cf0c6164 2150 transport_instance * tb,
0e66b3b6 2151#ifdef EXPERIMENTAL_DANE
cf0c6164 2152 dns_answer * tlsa_dnsa,
0e66b3b6 2153#endif
cf0c6164 2154 uschar ** errstr)
059ec3d9 2155{
a7538db1
JH
2156smtp_transport_options_block * ob =
2157 (smtp_transport_options_block *)tb->options_block;
f69979cf 2158static uschar peerdn[256];
868f5672 2159uschar * expciphers;
059ec3d9 2160int rc;
817d9f57 2161static uschar cipherbuf[256];
043b1248
JH
2162
2163#ifndef DISABLE_OCSP
043b1248 2164BOOL request_ocsp = FALSE;
6634ac8d 2165BOOL require_ocsp = FALSE;
043b1248 2166#endif
043b1248
JH
2167
2168#ifdef EXPERIMENTAL_DANE
594706ea 2169tls_out.tlsa_usage = 0;
043b1248
JH
2170#endif
2171
f2de3a33 2172#ifndef DISABLE_OCSP
043b1248 2173 {
4f59c424
JH
2174# ifdef EXPERIMENTAL_DANE
2175 if ( tlsa_dnsa
2176 && ob->hosts_request_ocsp[0] == '*'
2177 && ob->hosts_request_ocsp[1] == '\0'
2178 )
2179 {
2180 /* Unchanged from default. Use a safer one under DANE */
2181 request_ocsp = TRUE;
2182 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2183 " {= {4}{$tls_out_tlsa_usage}} } "
2184 " {*}{}}";
2185 }
2186# endif
2187
5130845b
JH
2188 if ((require_ocsp =
2189 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
fca41d5a
JH
2190 request_ocsp = TRUE;
2191 else
fca41d5a 2192# ifdef EXPERIMENTAL_DANE
4f59c424 2193 if (!request_ocsp)
fca41d5a 2194# endif
5130845b
JH
2195 request_ocsp =
2196 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
043b1248 2197 }
f5d78688 2198#endif
059ec3d9 2199
65867078
JH
2200rc = tls_init(&client_ctx, host, NULL,
2201 ob->tls_certificate, ob->tls_privatekey,
f2de3a33 2202#ifndef DISABLE_OCSP
44662487 2203 (void *)(long)request_ocsp,
3f7eeb86 2204#endif
cf0c6164 2205 addr, &client_static_cbinfo, errstr);
059ec3d9
PH
2206if (rc != OK) return rc;
2207
817d9f57 2208tls_out.certificate_verified = FALSE;
a2ff477a 2209client_verify_callback_called = FALSE;
059ec3d9 2210
65867078 2211if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
cf0c6164 2212 &expciphers, errstr))
059ec3d9
PH
2213 return FAIL;
2214
2215/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2216are separated by underscores. So that I can use either form in my tests, and
2217also for general convenience, we turn underscores into hyphens here. */
2218
cf0c6164 2219if (expciphers)
059ec3d9
PH
2220 {
2221 uschar *s = expciphers;
cf0c6164 2222 while (*s) { if (*s == '_') *s = '-'; s++; }
059ec3d9 2223 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 2224 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
cf0c6164 2225 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
059ec3d9
PH
2226 }
2227
043b1248 2228#ifdef EXPERIMENTAL_DANE
0e66b3b6 2229if (tlsa_dnsa)
a63be306 2230 {
02af313d
JH
2231 SSL_CTX_set_verify(client_ctx,
2232 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2233 verify_callback_client_dane);
e5cccda9 2234
043b1248 2235 if (!DANESSL_library_init())
cf0c6164 2236 return tls_error(US"library init", host, NULL, errstr);
043b1248 2237 if (DANESSL_CTX_init(client_ctx) <= 0)
cf0c6164 2238 return tls_error(US"context init", host, NULL, errstr);
043b1248
JH
2239 }
2240else
e51c7be2 2241
043b1248
JH
2242#endif
2243
cf0c6164
JH
2244 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob,
2245 client_static_cbinfo, errstr)) != OK)
65867078 2246 return rc;
059ec3d9 2247
65867078 2248if ((client_ssl = SSL_new(client_ctx)) == NULL)
cf0c6164 2249 return tls_error(US"SSL_new", host, NULL, errstr);
817d9f57
JH
2250SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
2251SSL_set_fd(client_ssl, fd);
2252SSL_set_connect_state(client_ssl);
059ec3d9 2253
65867078 2254if (ob->tls_sni)
3f0945ff 2255 {
cf0c6164 2256 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni, errstr))
3f0945ff 2257 return FAIL;
cf0c6164 2258 if (!tls_out.sni)
2c9a0e86
PP
2259 {
2260 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2261 }
ec4b68e5 2262 else if (!Ustrlen(tls_out.sni))
817d9f57 2263 tls_out.sni = NULL;
3f0945ff
PP
2264 else
2265 {
35731706 2266#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
2267 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
2268 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706 2269#else
66802652 2270 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
02d9264f 2271 tls_out.sni);
35731706 2272#endif
3f0945ff
PP
2273 }
2274 }
2275
594706ea 2276#ifdef EXPERIMENTAL_DANE
0e66b3b6 2277if (tlsa_dnsa)
cf0c6164 2278 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa, errstr)) != OK)
594706ea
JH
2279 return rc;
2280#endif
2281
f2de3a33 2282#ifndef DISABLE_OCSP
f5d78688
JH
2283/* Request certificate status at connection-time. If the server
2284does OCSP stapling we will get the callback (set in tls_init()) */
b50c8b84 2285# ifdef EXPERIMENTAL_DANE
44662487
JH
2286if (request_ocsp)
2287 {
594706ea 2288 const uschar * s;
41afb5cb
JH
2289 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2290 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
594706ea
JH
2291 )
2292 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2293 this means we avoid the OCSP request, we wasted the setup
2294 cost in tls_init(). */
5130845b
JH
2295 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2296 request_ocsp = require_ocsp
2297 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
594706ea
JH
2298 }
2299 }
b50c8b84
JH
2300# endif
2301
594706ea
JH
2302if (request_ocsp)
2303 {
f5d78688 2304 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
44662487
JH
2305 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2306 tls_out.ocsp = OCSP_NOT_RESP;
2307 }
f5d78688
JH
2308#endif
2309
0cbf2b82 2310#ifndef DISABLE_EVENT
774ef2d7 2311client_static_cbinfo->event_action = tb->event_action;
a7538db1 2312#endif
043b1248 2313
059ec3d9
PH
2314/* There doesn't seem to be a built-in timeout on connection. */
2315
2316DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2317sigalrm_seen = FALSE;
65867078 2318alarm(ob->command_timeout);
817d9f57 2319rc = SSL_connect(client_ssl);
059ec3d9
PH
2320alarm(0);
2321
043b1248 2322#ifdef EXPERIMENTAL_DANE
0e66b3b6 2323if (tlsa_dnsa)
fde080a4 2324 DANESSL_cleanup(client_ssl);
043b1248
JH
2325#endif
2326
059ec3d9 2327if (rc <= 0)
cf0c6164
JH
2328 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL,
2329 errstr);
059ec3d9
PH
2330
2331DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2332
f69979cf 2333peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
059ec3d9 2334
817d9f57
JH
2335construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2336tls_out.cipher = cipherbuf;
059ec3d9 2337
9d1c15ef
JH
2338/* Record the certificate we presented */
2339 {
2340 X509 * crt = SSL_get_certificate(client_ssl);
2341 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2342 }
2343
817d9f57 2344tls_out.active = fd;
059ec3d9
PH
2345return OK;
2346}
2347
2348
2349
2350
2351
2352/*************************************************
2353* TLS version of getc *
2354*************************************************/
2355
2356/* This gets the next byte from the TLS input buffer. If the buffer is empty,
2357it refills the buffer via the SSL reading function.
2358
bd8fbe36 2359Arguments: lim Maximum amount to read/buffer
059ec3d9 2360Returns: the next character or EOF
817d9f57
JH
2361
2362Only used by the server-side TLS.
059ec3d9
PH
2363*/
2364
2365int
bd8fbe36 2366tls_getc(unsigned lim)
059ec3d9
PH
2367{
2368if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2369 {
2370 int error;
2371 int inbytes;
2372
817d9f57 2373 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
c80c5570 2374 ssl_xfer_buffer, ssl_xfer_buffer_size);
059ec3d9
PH
2375
2376 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
bd8fbe36
JH
2377 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2378 MIN(ssl_xfer_buffer_size, lim));
817d9f57 2379 error = SSL_get_error(server_ssl, inbytes);
059ec3d9
PH
2380 alarm(0);
2381
2382 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2383 closed down, not that the socket itself has been closed down. Revert to
2384 non-SSL handling. */
2385
2386 if (error == SSL_ERROR_ZERO_RETURN)
2387 {
2388 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2389
2390 receive_getc = smtp_getc;
584e96c6 2391 receive_get_cache = smtp_get_cache;
059ec3d9
PH
2392 receive_ungetc = smtp_ungetc;
2393 receive_feof = smtp_feof;
2394 receive_ferror = smtp_ferror;
58eb016e 2395 receive_smtp_buffered = smtp_buffered;
059ec3d9 2396
817d9f57
JH
2397 SSL_free(server_ssl);
2398 server_ssl = NULL;
2399 tls_in.active = -1;
2400 tls_in.bits = 0;
2401 tls_in.cipher = NULL;
2402 tls_in.peerdn = NULL;
2403 tls_in.sni = NULL;
059ec3d9 2404
bd8fbe36 2405 return smtp_getc(lim);
059ec3d9
PH
2406 }
2407
2408 /* Handle genuine errors */
2409
ba084640
PP
2410 else if (error == SSL_ERROR_SSL)
2411 {
2412 ERR_error_string(ERR_get_error(), ssl_errstring);
89dd51cd 2413 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
ba084640
PP
2414 ssl_xfer_error = 1;
2415 return EOF;
2416 }
2417
059ec3d9
PH
2418 else if (error != SSL_ERROR_NONE)
2419 {
2420 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2421 ssl_xfer_error = 1;
2422 return EOF;
2423 }
c80c5570 2424
80a47a2c
TK
2425#ifndef DISABLE_DKIM
2426 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2427#endif
059ec3d9
PH
2428 ssl_xfer_buffer_hwm = inbytes;
2429 ssl_xfer_buffer_lwm = 0;
2430 }
2431
2432/* Something in the buffer; return next uschar */
2433
2434return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2435}
2436
584e96c6
JH
2437void
2438tls_get_cache()
2439{
9960d1e5 2440#ifndef DISABLE_DKIM
584e96c6
JH
2441int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2442if (n > 0)
2443 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
584e96c6 2444#endif
9960d1e5 2445}
584e96c6 2446
059ec3d9
PH
2447
2448
2449/*************************************************
2450* Read bytes from TLS channel *
2451*************************************************/
2452
2453/*
2454Arguments:
2455 buff buffer of data
2456 len size of buffer
2457
2458Returns: the number of bytes read
2459 -1 after a failed read
817d9f57
JH
2460
2461Only used by the client-side TLS.
059ec3d9
PH
2462*/
2463
2464int
389ca47a 2465tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 2466{
389ca47a 2467SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
2468int inbytes;
2469int error;
2470
389ca47a 2471DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 2472 buff, (unsigned int)len);
059ec3d9 2473
389ca47a
JH
2474inbytes = SSL_read(ssl, CS buff, len);
2475error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
2476
2477if (error == SSL_ERROR_ZERO_RETURN)
2478 {
2479 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2480 return -1;
2481 }
2482else if (error != SSL_ERROR_NONE)
059ec3d9 2483 return -1;
059ec3d9
PH
2484
2485return inbytes;
2486}
2487
2488
2489
2490
2491
2492/*************************************************
2493* Write bytes down TLS channel *
2494*************************************************/
2495
2496/*
2497Arguments:
817d9f57 2498 is_server channel specifier
059ec3d9
PH
2499 buff buffer of data
2500 len number of bytes
2501
2502Returns: the number of bytes after a successful write,
2503 -1 after a failed write
817d9f57
JH
2504
2505Used by both server-side and client-side TLS.
059ec3d9
PH
2506*/
2507
2508int
817d9f57 2509tls_write(BOOL is_server, const uschar *buff, size_t len)
059ec3d9
PH
2510{
2511int outbytes;
2512int error;
2513int left = len;
817d9f57 2514SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9 2515
c80c5570 2516DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
059ec3d9
PH
2517while (left > 0)
2518 {
c80c5570 2519 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
2520 outbytes = SSL_write(ssl, CS buff, left);
2521 error = SSL_get_error(ssl, outbytes);
2522 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2523 switch (error)
2524 {
2525 case SSL_ERROR_SSL:
96f5fe4c
JH
2526 ERR_error_string(ERR_get_error(), ssl_errstring);
2527 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2528 return -1;
059ec3d9
PH
2529
2530 case SSL_ERROR_NONE:
96f5fe4c
JH
2531 left -= outbytes;
2532 buff += outbytes;
2533 break;
059ec3d9
PH
2534
2535 case SSL_ERROR_ZERO_RETURN:
96f5fe4c
JH
2536 log_write(0, LOG_MAIN, "SSL channel closed on write");
2537 return -1;
059ec3d9 2538
817d9f57 2539 case SSL_ERROR_SYSCALL:
96f5fe4c
JH
2540 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2541 sender_fullhost ? sender_fullhost : US"<unknown>",
2542 strerror(errno));
2543 return -1;
817d9f57 2544
059ec3d9 2545 default:
96f5fe4c
JH
2546 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2547 return -1;
059ec3d9
PH
2548 }
2549 }
2550return len;
2551}
2552
2553
2554
2555/*************************************************
2556* Close down a TLS session *
2557*************************************************/
2558
2559/* This is also called from within a delivery subprocess forked from the
2560daemon, to shut down the TLS library, without actually doing a shutdown (which
2561would tamper with the SSL session in the parent process).
2562
2563Arguments: TRUE if SSL_shutdown is to be called
2564Returns: nothing
817d9f57
JH
2565
2566Used by both server-side and client-side TLS.
059ec3d9
PH
2567*/
2568
2569void
817d9f57 2570tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 2571{
817d9f57 2572SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 2573int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
2574
2575if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
2576
2577if (shutdown)
2578 {
ec8b777a 2579 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 2580 SSL_shutdown(*sslp);
059ec3d9
PH
2581 }
2582
817d9f57
JH
2583SSL_free(*sslp);
2584*sslp = NULL;
059ec3d9 2585
817d9f57 2586*fdp = -1;
059ec3d9
PH
2587}
2588
36f12725
NM
2589
2590
2591
2592/*************************************************
3375e053
PP
2593* Let tls_require_ciphers be checked at startup *
2594*************************************************/
2595
2596/* The tls_require_ciphers option, if set, must be something which the
2597library can parse.
2598
2599Returns: NULL on success, or error message
2600*/
2601
2602uschar *
2603tls_validate_require_cipher(void)
2604{
2605SSL_CTX *ctx;
2606uschar *s, *expciphers, *err;
2607
2608/* this duplicates from tls_init(), we need a better "init just global
2609state, for no specific purpose" singleton function of our own */
2610
2611SSL_load_error_strings();
2612OpenSSL_add_ssl_algorithms();
2613#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2614/* SHA256 is becoming ever more popular. This makes sure it gets added to the
2615list of available digests. */
2616EVP_add_digest(EVP_sha256());
2617#endif
2618
2619if (!(tls_require_ciphers && *tls_require_ciphers))
2620 return NULL;
2621
cf0c6164
JH
2622if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
2623 &err))
3375e053
PP
2624 return US"failed to expand tls_require_ciphers";
2625
2626if (!(expciphers && *expciphers))
2627 return NULL;
2628
2629/* normalisation ripped from above */
2630s = expciphers;
2631while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2632
2633err = NULL;
2634
2635ctx = SSL_CTX_new(SSLv23_server_method());
2636if (!ctx)
2637 {
2638 ERR_error_string(ERR_get_error(), ssl_errstring);
2639 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2640 }
2641
2642DEBUG(D_tls)
2643 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2644
2645if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2646 {
2647 ERR_error_string(ERR_get_error(), ssl_errstring);
cf0c6164
JH
2648 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
2649 expciphers, ssl_errstring);
3375e053
PP
2650 }
2651
2652SSL_CTX_free(ctx);
2653
2654return err;
2655}
2656
2657
2658
2659
2660/*************************************************
36f12725
NM
2661* Report the library versions. *
2662*************************************************/
2663
2664/* There have historically been some issues with binary compatibility in
2665OpenSSL libraries; if Exim (like many other applications) is built against
2666one version of OpenSSL but the run-time linker picks up another version,
2667it can result in serious failures, including crashing with a SIGSEGV. So
2668report the version found by the compiler and the run-time version.
2669
f64a1e23
PP
2670Note: some OS vendors backport security fixes without changing the version
2671number/string, and the version date remains unchanged. The _build_ date
2672will change, so we can more usefully assist with version diagnosis by also
2673reporting the build date.
2674
36f12725
NM
2675Arguments: a FILE* to print the results to
2676Returns: nothing
2677*/
2678
2679void
2680tls_version_report(FILE *f)
2681{
754a0503 2682fprintf(f, "Library version: OpenSSL: Compile: %s\n"
f64a1e23
PP
2683 " Runtime: %s\n"
2684 " : %s\n",
754a0503 2685 OPENSSL_VERSION_TEXT,
f64a1e23
PP
2686 SSLeay_version(SSLEAY_VERSION),
2687 SSLeay_version(SSLEAY_BUILT_ON));
2688/* third line is 38 characters for the %s and the line is 73 chars long;
2689the OpenSSL output includes a "built on: " prefix already. */
36f12725
NM
2690}
2691
9e3331ea
TK
2692
2693
2694
2695/*************************************************
17c76198 2696* Random number generation *
9e3331ea
TK
2697*************************************************/
2698
2699/* Pseudo-random number generation. The result is not expected to be
2700cryptographically strong but not so weak that someone will shoot themselves
2701in the foot using it as a nonce in input in some email header scheme or
2702whatever weirdness they'll twist this into. The result should handle fork()
2703and avoid repeating sequences. OpenSSL handles that for us.
2704
2705Arguments:
2706 max range maximum
2707Returns a random number in range [0, max-1]
2708*/
2709
2710int
17c76198 2711vaguely_random_number(int max)
9e3331ea
TK
2712{
2713unsigned int r;
2714int i, needed_len;
de6135a0
PP
2715static pid_t pidlast = 0;
2716pid_t pidnow;
9e3331ea
TK
2717uschar *p;
2718uschar smallbuf[sizeof(r)];
2719
2720if (max <= 1)
2721 return 0;
2722
de6135a0
PP
2723pidnow = getpid();
2724if (pidnow != pidlast)
2725 {
2726 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2727 is unique for each thread", this doesn't apparently apply across processes,
2728 so our own warning from vaguely_random_number_fallback() applies here too.
2729 Fix per PostgreSQL. */
2730 if (pidlast != 0)
2731 RAND_cleanup();
2732 pidlast = pidnow;
2733 }
2734
9e3331ea
TK
2735/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2736if (!RAND_status())
2737 {
2738 randstuff r;
2739 gettimeofday(&r.tv, NULL);
2740 r.p = getpid();
2741
2742 RAND_seed((uschar *)(&r), sizeof(r));
2743 }
2744/* We're after pseudo-random, not random; if we still don't have enough data
2745in the internal PRNG then our options are limited. We could sleep and hope
2746for entropy to come along (prayer technique) but if the system is so depleted
2747in the first place then something is likely to just keep taking it. Instead,
2748we'll just take whatever little bit of pseudo-random we can still manage to
2749get. */
2750
2751needed_len = sizeof(r);
2752/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2753asked for a number less than 10. */
2754for (r = max, i = 0; r; ++i)
2755 r >>= 1;
2756i = (i + 7) / 8;
2757if (i < needed_len)
2758 needed_len = i;
2759
c8dfb21d 2760#ifdef EXIM_HAVE_RAND_PSEUDO
9e3331ea 2761/* We do not care if crypto-strong */
17c76198 2762i = RAND_pseudo_bytes(smallbuf, needed_len);
c8dfb21d
JH
2763#else
2764i = RAND_bytes(smallbuf, needed_len);
2765#endif
2766
17c76198
PP
2767if (i < 0)
2768 {
2769 DEBUG(D_all)
2770 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2771 return vaguely_random_number_fallback(max);
2772 }
2773
9e3331ea
TK
2774r = 0;
2775for (p = smallbuf; needed_len; --needed_len, ++p)
2776 {
2777 r *= 256;
2778 r += *p;
2779 }
2780
2781/* We don't particularly care about weighted results; if someone wants
2782smooth distribution and cares enough then they should submit a patch then. */
2783return r % max;
2784}
2785
77bb000f
PP
2786
2787
2788
2789/*************************************************
2790* OpenSSL option parse *
2791*************************************************/
2792
2793/* Parse one option for tls_openssl_options_parse below
2794
2795Arguments:
2796 name one option name
2797 value place to store a value for it
2798Returns success or failure in parsing
2799*/
2800
2801struct exim_openssl_option {
2802 uschar *name;
2803 long value;
2804};
2805/* We could use a macro to expand, but we need the ifdef and not all the
2806options document which version they were introduced in. Policylet: include
2807all options unless explicitly for DTLS, let the administrator choose which
2808to apply.
2809
2810This list is current as of:
e2fbf4a2
PP
2811 ==> 1.0.1b <==
2812Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2813*/
77bb000f
PP
2814static struct exim_openssl_option exim_openssl_options[] = {
2815/* KEEP SORTED ALPHABETICALLY! */
2816#ifdef SSL_OP_ALL
73a46702 2817 { US"all", SSL_OP_ALL },
77bb000f
PP
2818#endif
2819#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2820 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2821#endif
2822#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2823 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2824#endif
2825#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2826 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2827#endif
2828#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2829 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2830#endif
2831#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2832 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2833#endif
2834#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2835 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2836#endif
2837#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2838 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2839#endif
2840#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2841 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2842#endif
2843#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2844 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2845#endif
2846#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2847 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2848#endif
c80c5570
PP
2849#ifdef SSL_OP_NO_COMPRESSION
2850 { US"no_compression", SSL_OP_NO_COMPRESSION },
2851#endif
77bb000f 2852#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2853 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2854#endif
c0c7b2da
PP
2855#ifdef SSL_OP_NO_SSLv2
2856 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2857#endif
2858#ifdef SSL_OP_NO_SSLv3
2859 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2860#endif
2861#ifdef SSL_OP_NO_TICKET
2862 { US"no_ticket", SSL_OP_NO_TICKET },
2863#endif
2864#ifdef SSL_OP_NO_TLSv1
2865 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2866#endif
c80c5570
PP
2867#ifdef SSL_OP_NO_TLSv1_1
2868#if SSL_OP_NO_TLSv1_1 == 0x00000400L
2869 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2870#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2871#else
2872 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2873#endif
2874#endif
2875#ifdef SSL_OP_NO_TLSv1_2
2876 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2877#endif
e2fbf4a2
PP
2878#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2879 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2880#endif
77bb000f 2881#ifdef SSL_OP_SINGLE_DH_USE
73a46702 2882 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
2883#endif
2884#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 2885 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
2886#endif
2887#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 2888 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
2889#endif
2890#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 2891 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
2892#endif
2893#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 2894 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
2895#endif
2896#ifdef SSL_OP_TLS_D5_BUG
73a46702 2897 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
2898#endif
2899#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 2900 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
2901#endif
2902};
2903static int exim_openssl_options_size =
2904 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2905
c80c5570 2906
77bb000f
PP
2907static BOOL
2908tls_openssl_one_option_parse(uschar *name, long *value)
2909{
2910int first = 0;
2911int last = exim_openssl_options_size;
2912while (last > first)
2913 {
2914 int middle = (first + last)/2;
2915 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2916 if (c == 0)
2917 {
2918 *value = exim_openssl_options[middle].value;
2919 return TRUE;
2920 }
2921 else if (c > 0)
2922 first = middle + 1;
2923 else
2924 last = middle;
2925 }
2926return FALSE;
2927}
2928
2929
2930
2931
2932/*************************************************
2933* OpenSSL option parsing logic *
2934*************************************************/
2935
2936/* OpenSSL has a number of compatibility options which an administrator might
2937reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2938we look like log_selector.
2939
2940Arguments:
2941 option_spec the administrator-supplied string of options
2942 results ptr to long storage for the options bitmap
2943Returns success or failure
2944*/
2945
2946BOOL
2947tls_openssl_options_parse(uschar *option_spec, long *results)
2948{
2949long result, item;
2950uschar *s, *end;
2951uschar keep_c;
2952BOOL adding, item_parsed;
2953
0e944a0d 2954result = 0L;
b1770b6e 2955/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 2956 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
2957#ifdef SSL_OP_NO_SSLv2
2958result |= SSL_OP_NO_SSLv2;
2959#endif
a57b6200
JH
2960#ifdef SSL_OP_SINGLE_DH_USE
2961result |= SSL_OP_SINGLE_DH_USE;
2962#endif
77bb000f
PP
2963
2964if (option_spec == NULL)
2965 {
2966 *results = result;
2967 return TRUE;
2968 }
2969
2970for (s=option_spec; *s != '\0'; /**/)
2971 {
2972 while (isspace(*s)) ++s;
2973 if (*s == '\0')
2974 break;
2975 if (*s != '+' && *s != '-')
2976 {
2977 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 2978 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
2979 return FALSE;
2980 }
2981 adding = *s++ == '+';
2982 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2983 keep_c = *end;
2984 *end = '\0';
2985 item_parsed = tls_openssl_one_option_parse(s, &item);
96f5fe4c 2986 *end = keep_c;
77bb000f
PP
2987 if (!item_parsed)
2988 {
0e944a0d 2989 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
2990 return FALSE;
2991 }
2992 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2993 adding ? "adding" : "removing", result, item, s);
2994 if (adding)
2995 result |= item;
2996 else
2997 result &= ~item;
77bb000f
PP
2998 s = end;
2999 }
3000
3001*results = result;
3002return TRUE;
3003}
3004
9d1c15ef
JH
3005/* vi: aw ai sw=2
3006*/
059ec3d9 3007/* End of tls-openssl.c */