Fix memory leak during multi-message reception using STARTTLS
[exim.git] / src / src / tls-openssl.c
CommitLineData
059ec3d9
PH
1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
f9ba5e22 5/* Copyright (c) University of Cambridge 1995 - 2018 */
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
c0635b6d 31#ifdef SUPPORT_DANE
05e796ad 32# include "danessl.h"
85098ee7
JH
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)
260958d6 54# define EXIM_HAVE_SHA256 /*MMMM*/
c8dfb21d 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
8420742d 72# define EXIM_HAVE_OPENSSL_DH_BITS
34e3241d
PP
73# endif
74# if OPENSSL_VERSION_NUMBER >= 0x010000000L \
2dfb468b 75 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
34e3241d
PP
76# define EXIM_HAVE_OPENSSL_CHECKHOST
77# endif
11aa88b0 78#endif
10ca4f1c 79
11aa88b0
RA
80#if !defined(LIBRESSL_VERSION_NUMBER) \
81 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
10ca4f1c
JH
82# if !defined(OPENSSL_NO_ECDH)
83# if OPENSSL_VERSION_NUMBER >= 0x0090800fL
260958d6 84# define EXIM_HAVE_ECDH /*MMMM*/
10ca4f1c
JH
85# endif
86# if OPENSSL_VERSION_NUMBER >= 0x10002000L
10ca4f1c
JH
87# define EXIM_HAVE_OPENSSL_EC_NIST2NID
88# endif
89# endif
2dfb468b 90#endif
3bcbbbe2 91
67791ce4
JH
92#if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
93# warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
94# define DISABLE_OCSP
95#endif
96
a6510420
JH
97#ifdef EXIM_HAVE_OPENSSL_CHECKHOST
98# include <openssl/x509v3.h>
99#endif
100
059ec3d9
PH
101/* Structure for collecting random data for seeding. */
102
103typedef struct randstuff {
9e3331ea
TK
104 struct timeval tv;
105 pid_t p;
059ec3d9
PH
106} randstuff;
107
108/* Local static variables */
109
a2ff477a
JH
110static BOOL client_verify_callback_called = FALSE;
111static BOOL server_verify_callback_called = FALSE;
059ec3d9
PH
112static const uschar *sid_ctx = US"exim";
113
d4f09789
PP
114/* We have three different contexts to care about.
115
116Simple case: client, `client_ctx`
117 As a client, we can be doing a callout or cut-through delivery while receiving
118 a message. So we have a client context, which should have options initialised
119 from the SMTP Transport.
120
121Server:
122 There are two cases: with and without ServerNameIndication from the client.
123 Given TLS SNI, we can be using different keys, certs and various other
124 configuration settings, because they're re-expanded with $tls_sni set. This
125 allows vhosting with TLS. This SNI is sent in the handshake.
126 A client might not send SNI, so we need a fallback, and an initial setup too.
127 So as a server, we start out using `server_ctx`.
128 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
129 `server_sni` from `server_ctx` and then initialise settings by re-expanding
130 configuration.
131*/
132
817d9f57
JH
133static SSL_CTX *client_ctx = NULL;
134static SSL_CTX *server_ctx = NULL;
135static SSL *client_ssl = NULL;
136static SSL *server_ssl = NULL;
389ca47a 137
35731706 138#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57 139static SSL_CTX *server_sni = NULL;
35731706 140#endif
059ec3d9
PH
141
142static char ssl_errstring[256];
143
144static int ssl_session_timeout = 200;
a2ff477a
JH
145static BOOL client_verify_optional = FALSE;
146static BOOL server_verify_optional = FALSE;
059ec3d9 147
f5d78688 148static BOOL reexpand_tls_files_for_sni = FALSE;
059ec3d9
PH
149
150
7be682ca
PP
151typedef struct tls_ext_ctx_cb {
152 uschar *certificate;
153 uschar *privatekey;
f5d78688 154 BOOL is_server;
a6510420 155#ifndef DISABLE_OCSP
c3033f13 156 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
f5d78688
JH
157 union {
158 struct {
159 uschar *file;
160 uschar *file_expanded;
161 OCSP_RESPONSE *response;
162 } server;
163 struct {
44662487
JH
164 X509_STORE *verify_store; /* non-null if status requested */
165 BOOL verify_required;
f5d78688
JH
166 } client;
167 } u_ocsp;
3f7eeb86 168#endif
7be682ca
PP
169 uschar *dhparam;
170 /* these are cached from first expand */
171 uschar *server_cipher_list;
172 /* only passed down to tls_error: */
173 host_item *host;
55414b25 174 const uschar * verify_cert_hostnames;
0cbf2b82 175#ifndef DISABLE_EVENT
a7538db1
JH
176 uschar * event_action;
177#endif
7be682ca
PP
178} tls_ext_ctx_cb;
179
180/* should figure out a cleanup of API to handle state preserved per
181implementation, for various reasons, which can be void * in the APIs.
182For now, we hack around it. */
817d9f57
JH
183tls_ext_ctx_cb *client_static_cbinfo = NULL;
184tls_ext_ctx_cb *server_static_cbinfo = NULL;
7be682ca
PP
185
186static int
983207c1 187setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
cf0c6164 188 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
059ec3d9 189
3f7eeb86 190/* Callbacks */
3bcbbbe2 191#ifdef EXIM_HAVE_OPENSSL_TLSEXT
3f7eeb86 192static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
3bcbbbe2 193#endif
f2de3a33 194#ifndef DISABLE_OCSP
f5d78688 195static int tls_server_stapling_cb(SSL *s, void *arg);
3f7eeb86
PP
196#endif
197
059ec3d9
PH
198
199/*************************************************
200* Handle TLS error *
201*************************************************/
202
203/* Called from lots of places when errors occur before actually starting to do
204the TLS handshake, that is, while the session is still in clear. Always returns
205DEFER for a server and FAIL for a client so that most calls can use "return
206tls_error(...)" to do this processing and then give an appropriate return. A
207single function is used for both server and client, because it is called from
208some shared functions.
209
210Argument:
211 prefix text to include in the logged error
212 host NULL if setting up a server;
213 the connected host if setting up a client
7199e1ee 214 msg error message or NULL if we should ask OpenSSL
cf0c6164 215 errstr pointer to output error message
059ec3d9
PH
216
217Returns: OK/DEFER/FAIL
218*/
219
220static int
cf0c6164 221tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
059ec3d9 222{
c562fd30 223if (!msg)
7199e1ee
TF
224 {
225 ERR_error_string(ERR_get_error(), ssl_errstring);
cf0c6164 226 msg = US ssl_errstring;
7199e1ee
TF
227 }
228
cf0c6164
JH
229if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg);
230return host ? FAIL : DEFER;
059ec3d9
PH
231}
232
233
234
235/*************************************************
236* Callback to generate RSA key *
237*************************************************/
238
239/*
240Arguments:
3ae79556 241 s SSL connection (not used)
059ec3d9
PH
242 export not used
243 keylength keylength
244
245Returns: pointer to generated key
246*/
247
248static RSA *
249rsa_callback(SSL *s, int export, int keylength)
250{
251RSA *rsa_key;
c8dfb21d
JH
252#ifdef EXIM_HAVE_RSA_GENKEY_EX
253BIGNUM *bn = BN_new();
254#endif
255
059ec3d9
PH
256export = export; /* Shut picky compilers up */
257DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
c8dfb21d
JH
258
259#ifdef EXIM_HAVE_RSA_GENKEY_EX
260if ( !BN_set_word(bn, (unsigned long)RSA_F4)
f2cb6292 261 || !(rsa_key = RSA_new())
c8dfb21d
JH
262 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
263 )
264#else
23bb6982 265if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
c8dfb21d
JH
266#endif
267
059ec3d9
PH
268 {
269 ERR_error_string(ERR_get_error(), ssl_errstring);
270 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
271 ssl_errstring);
272 return NULL;
273 }
274return rsa_key;
275}
276
277
278
f5d78688 279/* Extreme debug
f2de3a33 280#ifndef DISABLE_OCSP
f5d78688
JH
281void
282x509_store_dump_cert_s_names(X509_STORE * store)
283{
284STACK_OF(X509_OBJECT) * roots= store->objs;
285int i;
286static uschar name[256];
287
288for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
289 {
290 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
291 if(tmp_obj->type == X509_LU_X509)
292 {
293 X509 * current_cert= tmp_obj->data.x509;
294 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
f69979cf 295 name[sizeof(name)-1] = '\0';
f5d78688
JH
296 debug_printf(" %s\n", name);
297 }
298 }
299}
300#endif
301*/
302
059ec3d9 303
0cbf2b82 304#ifndef DISABLE_EVENT
f69979cf
JH
305static int
306verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
307 BOOL *calledp, const BOOL *optionalp, const uschar * what)
308{
309uschar * ev;
310uschar * yield;
311X509 * old_cert;
312
313ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
314if (ev)
315 {
aaba7d03 316 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
f69979cf
JH
317 old_cert = tlsp->peercert;
318 tlsp->peercert = X509_dup(cert);
319 /* NB we do not bother setting peerdn */
320 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
321 {
322 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
323 "depth=%d cert=%s: %s",
324 tlsp == &tls_out ? deliver_host_address : sender_host_address,
325 what, depth, dn, yield);
326 *calledp = TRUE;
327 if (!*optionalp)
328 {
329 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
330 return 1; /* reject (leaving peercert set) */
331 }
332 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
333 "(host in tls_try_verify_hosts)\n");
334 }
335 X509_free(tlsp->peercert);
336 tlsp->peercert = old_cert;
337 }
338return 0;
339}
340#endif
341
059ec3d9
PH
342/*************************************************
343* Callback for verification *
344*************************************************/
345
346/* The SSL library does certificate verification if set up to do so. This
347callback has the current yes/no state is in "state". If verification succeeded,
f69979cf
JH
348we set the certificate-verified flag. If verification failed, what happens
349depends on whether the client is required to present a verifiable certificate
350or not.
059ec3d9
PH
351
352If verification is optional, we change the state to yes, but still log the
353verification error. For some reason (it really would help to have proper
354documentation of OpenSSL), this callback function then gets called again, this
f69979cf
JH
355time with state = 1. We must take care not to set the private verified flag on
356the second time through.
059ec3d9
PH
357
358Note: this function is not called if the client fails to present a certificate
359when asked. We get here only if a certificate has been received. Handling of
360optional verification for this case is done when requesting SSL to verify, by
361setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
362
a7538db1
JH
363May be called multiple times for different issues with a certificate, even
364for a given "depth" in the certificate chain.
365
059ec3d9 366Arguments:
f2f2c91b
JH
367 preverify_ok current yes/no state as 1/0
368 x509ctx certificate information.
369 tlsp per-direction (client vs. server) support data
370 calledp has-been-called flag
371 optionalp verification-is-optional flag
059ec3d9 372
f2f2c91b 373Returns: 0 if verification should fail, otherwise 1
059ec3d9
PH
374*/
375
376static int
f2f2c91b 377verify_callback(int preverify_ok, X509_STORE_CTX *x509ctx,
421aff85 378 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
059ec3d9 379{
421aff85 380X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
a7538db1 381int depth = X509_STORE_CTX_get_error_depth(x509ctx);
f69979cf 382uschar dn[256];
059ec3d9 383
f69979cf
JH
384X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
385dn[sizeof(dn)-1] = '\0';
059ec3d9 386
f2f2c91b 387if (preverify_ok == 0)
059ec3d9 388 {
f77197ae
JH
389 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
390 *verify_mode, sender_host_address)
391 : US"";
392 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
393 tlsp == &tls_out ? deliver_host_address : sender_host_address,
394 extra, depth,
395 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
a2ff477a 396 *calledp = TRUE;
9d1c15ef
JH
397 if (!*optionalp)
398 {
f69979cf
JH
399 if (!tlsp->peercert)
400 tlsp->peercert = X509_dup(cert); /* record failing cert */
401 return 0; /* reject */
9d1c15ef 402 }
059ec3d9
PH
403 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
404 "tls_try_verify_hosts)\n");
059ec3d9
PH
405 }
406
a7538db1 407else if (depth != 0)
059ec3d9 408 {
f69979cf 409 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
f2de3a33 410#ifndef DISABLE_OCSP
f5d78688
JH
411 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
412 { /* client, wanting stapling */
413 /* Add the server cert's signing chain as the one
414 for the verification of the OCSP stapled information. */
94431adb 415
f5d78688 416 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
421aff85 417 cert))
f5d78688 418 ERR_clear_error();
c3033f13 419 sk_X509_push(client_static_cbinfo->verify_stack, cert);
f5d78688
JH
420 }
421#endif
0cbf2b82 422#ifndef DISABLE_EVENT
f69979cf
JH
423 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
424 return 0; /* reject, with peercert set */
a7538db1 425#endif
059ec3d9
PH
426 }
427else
428 {
55414b25 429 const uschar * verify_cert_hostnames;
e51c7be2 430
e51c7be2
JH
431 if ( tlsp == &tls_out
432 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
433 /* client, wanting hostname check */
e51c7be2 434 {
f69979cf 435
740f36d4 436#ifdef EXIM_HAVE_OPENSSL_CHECKHOST
f69979cf
JH
437# ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
438# define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
439# endif
440# ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
441# define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
442# endif
e51c7be2 443 int sep = 0;
55414b25 444 const uschar * list = verify_cert_hostnames;
e51c7be2 445 uschar * name;
d8e7834a
JH
446 int rc;
447 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
f40d5be3 448 if ((rc = X509_check_host(cert, CCS name, 0,
8d692470 449 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
740f36d4
JH
450 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
451 NULL)))
d8e7834a
JH
452 {
453 if (rc < 0)
454 {
93a6fce2 455 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
f77197ae 456 tlsp == &tls_out ? deliver_host_address : sender_host_address);
d8e7834a
JH
457 name = NULL;
458 }
e51c7be2 459 break;
d8e7834a 460 }
e51c7be2 461 if (!name)
f69979cf 462#else
e51c7be2 463 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
f69979cf 464#endif
e51c7be2 465 {
f77197ae
JH
466 uschar * extra = verify_mode
467 ? string_sprintf(" (during %c-verify for [%s])",
468 *verify_mode, sender_host_address)
469 : US"";
e51c7be2 470 log_write(0, LOG_MAIN,
f77197ae
JH
471 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
472 tlsp == &tls_out ? deliver_host_address : sender_host_address,
473 extra, dn, verify_cert_hostnames);
a3ef7310
JH
474 *calledp = TRUE;
475 if (!*optionalp)
f69979cf
JH
476 {
477 if (!tlsp->peercert)
478 tlsp->peercert = X509_dup(cert); /* record failing cert */
479 return 0; /* reject */
480 }
a3ef7310
JH
481 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
482 "tls_try_verify_hosts)\n");
e51c7be2 483 }
f69979cf 484 }
e51c7be2 485
0cbf2b82 486#ifndef DISABLE_EVENT
f69979cf
JH
487 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
488 return 0; /* reject, with peercert set */
e51c7be2
JH
489#endif
490
93dcb1c2 491 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
f69979cf 492 *calledp ? "" : " authenticated", dn);
93dcb1c2
JH
493 if (!*calledp) tlsp->certificate_verified = TRUE;
494 *calledp = TRUE;
059ec3d9
PH
495 }
496
a7538db1 497return 1; /* accept, at least for this level */
059ec3d9
PH
498}
499
a2ff477a 500static int
f2f2c91b 501verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
a2ff477a 502{
f2f2c91b
JH
503return verify_callback(preverify_ok, x509ctx, &tls_out,
504 &client_verify_callback_called, &client_verify_optional);
a2ff477a
JH
505}
506
507static int
f2f2c91b 508verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
a2ff477a 509{
f2f2c91b
JH
510return verify_callback(preverify_ok, x509ctx, &tls_in,
511 &server_verify_callback_called, &server_verify_optional);
a2ff477a
JH
512}
513
059ec3d9 514
c0635b6d 515#ifdef SUPPORT_DANE
53a7196b 516
e5cccda9
JH
517/* This gets called *by* the dane library verify callback, which interposes
518itself.
519*/
520static int
f2f2c91b 521verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
e5cccda9
JH
522{
523X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
f69979cf 524uschar dn[256];
83b27293 525int depth = X509_STORE_CTX_get_error_depth(x509ctx);
5c75db2e 526#ifndef DISABLE_EVENT
f69979cf 527BOOL dummy_called, optional = FALSE;
83b27293 528#endif
e5cccda9 529
f69979cf
JH
530X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
531dn[sizeof(dn)-1] = '\0';
e5cccda9 532
f2f2c91b
JH
533DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
534 preverify_ok ? "ok":"BAD", depth, dn);
e5cccda9 535
0cbf2b82 536#ifndef DISABLE_EVENT
f69979cf
JH
537 if (verify_event(&tls_out, cert, depth, dn,
538 &dummy_called, &optional, US"DANE"))
539 return 0; /* reject, with peercert set */
83b27293
JH
540#endif
541
f2f2c91b 542if (preverify_ok == 1)
6fbf3599
JH
543 {
544 tls_out.dane_verified = tls_out.certificate_verified = TRUE;
545#ifndef DISABLE_OCSP
546 if (client_static_cbinfo->u_ocsp.client.verify_store)
547 { /* client, wanting stapling */
548 /* Add the server cert's signing chain as the one
549 for the verification of the OCSP stapled information. */
550
551 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
552 cert))
553 ERR_clear_error();
554 sk_X509_push(client_static_cbinfo->verify_stack, cert);
555 }
556#endif
557 }
f2f2c91b
JH
558else
559 {
560 int err = X509_STORE_CTX_get_error(x509ctx);
561 DEBUG(D_tls)
562 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
3c51463e 563 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
f2f2c91b
JH
564 preverify_ok = 1;
565 }
566return preverify_ok;
e5cccda9 567}
53a7196b 568
c0635b6d 569#endif /*SUPPORT_DANE*/
e5cccda9 570
059ec3d9
PH
571
572/*************************************************
573* Information callback *
574*************************************************/
575
576/* The SSL library functions call this from time to time to indicate what they
7be682ca
PP
577are doing. We copy the string to the debugging output when TLS debugging has
578been requested.
059ec3d9
PH
579
580Arguments:
581 s the SSL connection
582 where
583 ret
584
585Returns: nothing
586*/
587
588static void
589info_callback(SSL *s, int where, int ret)
590{
591where = where;
592ret = ret;
593DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
594}
595
596
597
598/*************************************************
599* Initialize for DH *
600*************************************************/
601
602/* If dhparam is set, expand it, and load up the parameters for DH encryption.
603
604Arguments:
038597d2 605 sctx The current SSL CTX (inbound or outbound)
a799883d 606 dhparam DH parameter file or fixed parameter identity string
7199e1ee 607 host connected host, if client; NULL if server
cf0c6164 608 errstr error string pointer
059ec3d9
PH
609
610Returns: TRUE if OK (nothing to set up, or setup worked)
611*/
612
613static BOOL
cf0c6164 614init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
059ec3d9 615{
059ec3d9
PH
616BIO *bio;
617DH *dh;
618uschar *dhexpanded;
a799883d 619const char *pem;
6600985a 620int dh_bitsize;
059ec3d9 621
cf0c6164 622if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
059ec3d9
PH
623 return FALSE;
624
0df4ab80 625if (!dhexpanded || !*dhexpanded)
a799883d 626 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
a799883d 627else if (dhexpanded[0] == '/')
059ec3d9 628 {
0df4ab80 629 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
059ec3d9 630 {
7199e1ee 631 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
cf0c6164 632 host, US strerror(errno), errstr);
a799883d 633 return FALSE;
059ec3d9 634 }
a799883d
PP
635 }
636else
637 {
638 if (Ustrcmp(dhexpanded, "none") == 0)
059ec3d9 639 {
a799883d
PP
640 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
641 return TRUE;
059ec3d9 642 }
a799883d 643
0df4ab80 644 if (!(pem = std_dh_prime_named(dhexpanded)))
a799883d
PP
645 {
646 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
cf0c6164 647 host, US strerror(errno), errstr);
a799883d
PP
648 return FALSE;
649 }
650 bio = BIO_new_mem_buf(CS pem, -1);
651 }
652
0df4ab80 653if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
a799883d 654 {
059ec3d9 655 BIO_free(bio);
a799883d 656 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
cf0c6164 657 host, NULL, errstr);
a799883d
PP
658 return FALSE;
659 }
660
6600985a
PP
661/* note: our default limit of 2236 is not a multiple of 8; the limit comes from
662 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
663 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
664 * If someone wants to dance at the edge, then they can raise the limit or use
665 * current libraries. */
666#ifdef EXIM_HAVE_OPENSSL_DH_BITS
667/* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
668 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
669dh_bitsize = DH_bits(dh);
670#else
671dh_bitsize = 8 * DH_size(dh);
672#endif
673
a799883d
PP
674/* Even if it is larger, we silently return success rather than cause things
675 * to fail out, so that a too-large DH will not knock out all TLS; it's a
676 * debatable choice. */
6600985a 677if (dh_bitsize > tls_dh_max_bits)
a799883d
PP
678 {
679 DEBUG(D_tls)
170f4904 680 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
6600985a 681 dh_bitsize, tls_dh_max_bits);
a799883d
PP
682 }
683else
684 {
685 SSL_CTX_set_tmp_dh(sctx, dh);
686 DEBUG(D_tls)
687 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
6600985a 688 dhexpanded ? dhexpanded : US"default", dh_bitsize);
059ec3d9
PH
689 }
690
a799883d
PP
691DH_free(dh);
692BIO_free(bio);
693
694return TRUE;
059ec3d9
PH
695}
696
697
698
699
038597d2
PP
700/*************************************************
701* Initialize for ECDH *
702*************************************************/
703
704/* Load parameters for ECDH encryption.
705
706For now, we stick to NIST P-256 because: it's simple and easy to configure;
707it avoids any patent issues that might bite redistributors; despite events in
708the news and concerns over curve choices, we're not cryptographers, we're not
709pretending to be, and this is "good enough" to be better than no support,
710protecting against most adversaries. Given another year or two, there might
711be sufficient clarity about a "right" way forward to let us make an informed
712decision, instead of a knee-jerk reaction.
713
714Longer-term, we should look at supporting both various named curves and
715external files generated with "openssl ecparam", much as we do for init_dh().
716We should also support "none" as a value, to explicitly avoid initialisation.
717
718Patches welcome.
719
720Arguments:
721 sctx The current SSL CTX (inbound or outbound)
722 host connected host, if client; NULL if server
cf0c6164 723 errstr error string pointer
038597d2
PP
724
725Returns: TRUE if OK (nothing to set up, or setup worked)
726*/
727
728static BOOL
cf0c6164 729init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
038597d2 730{
63f0dbe0
JH
731#ifdef OPENSSL_NO_ECDH
732return TRUE;
733#else
734
10ca4f1c
JH
735EC_KEY * ecdh;
736uschar * exp_curve;
737int nid;
738BOOL rv;
739
038597d2
PP
740if (host) /* No ECDH setup for clients, only for servers */
741 return TRUE;
742
10ca4f1c 743# ifndef EXIM_HAVE_ECDH
038597d2
PP
744DEBUG(D_tls)
745 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
746return TRUE;
038597d2 747# else
10ca4f1c 748
cf0c6164 749if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
10ca4f1c
JH
750 return FALSE;
751if (!exp_curve || !*exp_curve)
752 return TRUE;
753
8e53a4fc 754/* "auto" needs to be handled carefully.
4c04137d 755 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
8e53a4fc 756 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
4c04137d 757 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
8e53a4fc
HSHR
758 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
759 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
760 */
10ca4f1c 761if (Ustrcmp(exp_curve, "auto") == 0)
038597d2 762 {
8e53a4fc 763#if OPENSSL_VERSION_NUMBER < 0x10002000L
10ca4f1c 764 DEBUG(D_tls) debug_printf(
8e53a4fc 765 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
78a3bbd5 766 exp_curve = US"prime256v1";
8e53a4fc
HSHR
767#else
768# if defined SSL_CTRL_SET_ECDH_AUTO
769 DEBUG(D_tls) debug_printf(
770 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
10ca4f1c
JH
771 SSL_CTX_set_ecdh_auto(sctx, 1);
772 return TRUE;
8e53a4fc
HSHR
773# else
774 DEBUG(D_tls) debug_printf(
775 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
776 return TRUE;
777# endif
778#endif
10ca4f1c 779 }
038597d2 780
10ca4f1c
JH
781DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
782if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
783# ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
784 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
785# endif
786 )
787 {
cf0c6164
JH
788 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
789 host, NULL, errstr);
10ca4f1c
JH
790 return FALSE;
791 }
038597d2 792
10ca4f1c
JH
793if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
794 {
cf0c6164 795 tls_error(US"Unable to create ec curve", host, NULL, errstr);
10ca4f1c 796 return FALSE;
038597d2 797 }
10ca4f1c
JH
798
799/* The "tmp" in the name here refers to setting a temporary key
800not to the stability of the interface. */
801
802if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
cf0c6164 803 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
10ca4f1c
JH
804else
805 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
806
807EC_KEY_free(ecdh);
808return !rv;
809
810# endif /*EXIM_HAVE_ECDH*/
811#endif /*OPENSSL_NO_ECDH*/
038597d2
PP
812}
813
814
815
816
f2de3a33 817#ifndef DISABLE_OCSP
3f7eeb86
PP
818/*************************************************
819* Load OCSP information into state *
820*************************************************/
f5d78688 821/* Called to load the server OCSP response from the given file into memory, once
3f7eeb86
PP
822caller has determined this is needed. Checks validity. Debugs a message
823if invalid.
824
825ASSUMES: single response, for single cert.
826
827Arguments:
828 sctx the SSL_CTX* to update
829 cbinfo various parts of session state
830 expanded the filename putatively holding an OCSP response
831
832*/
833
834static void
f5d78688 835ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
3f7eeb86 836{
ee5b1e28
JH
837BIO * bio;
838OCSP_RESPONSE * resp;
839OCSP_BASICRESP * basic_response;
840OCSP_SINGLERESP * single_response;
841ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
ee5b1e28 842STACK_OF(X509) * sk;
3f7eeb86
PP
843unsigned long verify_flags;
844int status, reason, i;
845
f5d78688
JH
846cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
847if (cbinfo->u_ocsp.server.response)
3f7eeb86 848 {
f5d78688
JH
849 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
850 cbinfo->u_ocsp.server.response = NULL;
3f7eeb86
PP
851 }
852
ee5b1e28 853if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
3f7eeb86
PP
854 {
855 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
f5d78688 856 cbinfo->u_ocsp.server.file_expanded);
3f7eeb86
PP
857 return;
858 }
859
860resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
861BIO_free(bio);
862if (!resp)
863 {
864 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
865 return;
866 }
867
ee5b1e28 868if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
3f7eeb86
PP
869 {
870 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
871 OCSP_response_status_str(status), status);
f5d78688 872 goto bad;
3f7eeb86
PP
873 }
874
ee5b1e28 875if (!(basic_response = OCSP_response_get1_basic(resp)))
3f7eeb86
PP
876 {
877 DEBUG(D_tls)
878 debug_printf("OCSP response parse error: unable to extract basic response.\n");
f5d78688 879 goto bad;
3f7eeb86
PP
880 }
881
c3033f13 882sk = cbinfo->verify_stack;
3f7eeb86
PP
883verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
884
885/* May need to expose ability to adjust those flags?
886OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
887OCSP_TRUSTOTHER OCSP_NOINTERN */
888
4c04137d 889/* This does a full verify on the OCSP proof before we load it for serving
ee5b1e28
JH
890up; possibly overkill - just date-checks might be nice enough.
891
892OCSP_basic_verify takes a "store" arg, but does not
893use it for the chain verification, which is all we do
894when OCSP_NOVERIFY is set. The content from the wire
895"basic_response" and a cert-stack "sk" are all that is used.
896
c3033f13
JH
897We have a stack, loaded in setup_certs() if tls_verify_certificates
898was a file (not a directory, or "system"). It is unfortunate we
899cannot used the connection context store, as that would neatly
900handle the "system" case too, but there seems to be no library
901function for getting a stack from a store.
e3555426 902[ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
c3033f13
JH
903We do not free the stack since it could be needed a second time for
904SNI handling.
905
4c04137d 906Separately we might try to replace using OCSP_basic_verify() - which seems to not
ee5b1e28
JH
907be a public interface into the OpenSSL library (there's no manual entry) -
908But what with? We also use OCSP_basic_verify in the client stapling callback.
4c04137d 909And there we NEED it; we must verify that status... unless the
ee5b1e28
JH
910library does it for us anyway? */
911
912if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
3f7eeb86 913 {
ee5b1e28
JH
914 DEBUG(D_tls)
915 {
3f7eeb86
PP
916 ERR_error_string(ERR_get_error(), ssl_errstring);
917 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
f5d78688
JH
918 }
919 goto bad;
3f7eeb86
PP
920 }
921
922/* Here's the simplifying assumption: there's only one response, for the
923one certificate we use, and nothing for anything else in a chain. If this
924proves false, we need to extract a cert id from our issued cert
925(tls_certificate) and use that for OCSP_resp_find_status() (which finds the
926right cert in the stack and then calls OCSP_single_get0_status()).
927
928I'm hoping to avoid reworking a bunch more of how we handle state here. */
ee5b1e28
JH
929
930if (!(single_response = OCSP_resp_get0(basic_response, 0)))
3f7eeb86
PP
931 {
932 DEBUG(D_tls)
933 debug_printf("Unable to get first response from OCSP basic response.\n");
f5d78688 934 goto bad;
3f7eeb86
PP
935 }
936
937status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
f5d78688 938if (status != V_OCSP_CERTSTATUS_GOOD)
3f7eeb86 939 {
f5d78688
JH
940 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
941 OCSP_cert_status_str(status), status,
942 OCSP_crl_reason_str(reason), reason);
943 goto bad;
3f7eeb86
PP
944 }
945
946if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
947 {
948 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
f5d78688 949 goto bad;
3f7eeb86
PP
950 }
951
f5d78688 952supply_response:
47195144 953 cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/
f5d78688
JH
954return;
955
956bad:
018058b2
JH
957 if (running_in_test_harness)
958 {
959 extern char ** environ;
960 uschar ** p;
47195144 961 if (environ) for (p = USS environ; *p; p++)
018058b2
JH
962 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
963 {
964 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
965 goto supply_response;
966 }
967 }
f5d78688 968return;
3f7eeb86 969}
f2de3a33 970#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
971
972
973
974
23bb6982
JH
975/* Create and install a selfsigned certificate, for use in server mode */
976
977static int
cf0c6164 978tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
23bb6982
JH
979{
980X509 * x509 = NULL;
981EVP_PKEY * pkey;
982RSA * rsa;
983X509_NAME * name;
984uschar * where;
985
986where = US"allocating pkey";
987if (!(pkey = EVP_PKEY_new()))
988 goto err;
989
990where = US"allocating cert";
991if (!(x509 = X509_new()))
992 goto err;
993
994where = US"generating pkey";
3ae79556 995if (!(rsa = rsa_callback(NULL, 0, 1024)))
23bb6982
JH
996 goto err;
997
4c04137d 998where = US"assigning pkey";
23bb6982
JH
999if (!EVP_PKEY_assign_RSA(pkey, rsa))
1000 goto err;
1001
1002X509_set_version(x509, 2); /* N+1 - version 3 */
1003ASN1_INTEGER_set(X509_get_serialNumber(x509), 0);
1004X509_gmtime_adj(X509_get_notBefore(x509), 0);
1005X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1006X509_set_pubkey(x509, pkey);
1007
1008name = X509_get_subject_name(x509);
1009X509_NAME_add_entry_by_txt(name, "C",
4dc2379a 1010 MBSTRING_ASC, CUS "UK", -1, -1, 0);
23bb6982 1011X509_NAME_add_entry_by_txt(name, "O",
4dc2379a 1012 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
23bb6982 1013X509_NAME_add_entry_by_txt(name, "CN",
4dc2379a 1014 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
23bb6982
JH
1015X509_set_issuer_name(x509, name);
1016
1017where = US"signing cert";
1018if (!X509_sign(x509, pkey, EVP_md5()))
1019 goto err;
1020
1021where = US"installing selfsign cert";
1022if (!SSL_CTX_use_certificate(sctx, x509))
1023 goto err;
1024
1025where = US"installing selfsign key";
1026if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1027 goto err;
1028
1029return OK;
1030
1031err:
cf0c6164 1032 (void) tls_error(where, NULL, NULL, errstr);
23bb6982
JH
1033 if (x509) X509_free(x509);
1034 if (pkey) EVP_PKEY_free(pkey);
1035 return DEFER;
1036}
1037
1038
1039
1040
ba86e143
JH
1041static int
1042tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1043 uschar ** errstr)
1044{
1045DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file);
1046if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1047 return tls_error(string_sprintf(
1048 "SSL_CTX_use_certificate_chain_file file=%s", file),
1049 cbinfo->host, NULL, errstr);
1050return 0;
1051}
1052
1053static int
1054tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1055 uschar ** errstr)
1056{
1057DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file);
1058if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1059 return tls_error(string_sprintf(
1060 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1061return 0;
1062}
1063
1064
059ec3d9 1065/*************************************************
7be682ca
PP
1066* Expand key and cert file specs *
1067*************************************************/
1068
f5d78688 1069/* Called once during tls_init and possibly again during TLS setup, for a
7be682ca
PP
1070new context, if Server Name Indication was used and tls_sni was seen in
1071the certificate string.
1072
1073Arguments:
1074 sctx the SSL_CTX* to update
1075 cbinfo various parts of session state
cf0c6164 1076 errstr error string pointer
7be682ca
PP
1077
1078Returns: OK/DEFER/FAIL
1079*/
1080
1081static int
cf0c6164
JH
1082tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1083 uschar ** errstr)
7be682ca
PP
1084{
1085uschar *expanded;
1086
23bb6982 1087if (!cbinfo->certificate)
7be682ca 1088 {
ba86e143 1089 if (!cbinfo->is_server) /* client */
23bb6982
JH
1090 return OK;
1091 /* server */
cf0c6164 1092 if (tls_install_selfsign(sctx, errstr) != OK)
23bb6982 1093 return DEFER;
7be682ca 1094 }
23bb6982
JH
1095else
1096 {
ba86e143
JH
1097 int err;
1098
23bb6982
JH
1099 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1100 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1101 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1102 )
1103 reexpand_tls_files_for_sni = TRUE;
7be682ca 1104
cf0c6164 1105 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
23bb6982
JH
1106 return DEFER;
1107
ba86e143
JH
1108 if (expanded)
1109 if (cbinfo->is_server)
1110 {
1111 const uschar * file_list = expanded;
1112 int sep = 0;
1113 uschar * file;
1114
1115 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1116 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1117 return err;
1118 }
1119 else /* would there ever be a need for multiple client certs? */
1120 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1121 return err;
7be682ca 1122
23bb6982 1123 if (cbinfo->privatekey != NULL &&
cf0c6164 1124 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
23bb6982 1125 return DEFER;
7be682ca 1126
23bb6982
JH
1127 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1128 of the expansion is an empty string, ignore it also, and assume the private
1129 key is in the same file as the certificate. */
1130
1131 if (expanded && *expanded)
ba86e143
JH
1132 if (cbinfo->is_server)
1133 {
1134 const uschar * file_list = expanded;
1135 int sep = 0;
1136 uschar * file;
1137
1138 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1139 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1140 return err;
1141 }
1142 else /* would there ever be a need for multiple client certs? */
1143 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1144 return err;
7be682ca
PP
1145 }
1146
f2de3a33 1147#ifndef DISABLE_OCSP
f40d5be3 1148if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
3f7eeb86 1149 {
47195144 1150 /*XXX stack*/
cf0c6164 1151 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
3f7eeb86
PP
1152 return DEFER;
1153
f40d5be3 1154 if (expanded && *expanded)
3f7eeb86
PP
1155 {
1156 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
f40d5be3
JH
1157 if ( cbinfo->u_ocsp.server.file_expanded
1158 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
3f7eeb86 1159 {
f40d5be3
JH
1160 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1161 }
1162 else
f40d5be3 1163 ocsp_load_response(sctx, cbinfo, expanded);
3f7eeb86
PP
1164 }
1165 }
1166#endif
1167
7be682ca
PP
1168return OK;
1169}
1170
1171
1172
1173
1174/*************************************************
1175* Callback to handle SNI *
1176*************************************************/
1177
1178/* Called when acting as server during the TLS session setup if a Server Name
1179Indication extension was sent by the client.
1180
1181API documentation is OpenSSL s_server.c implementation.
1182
1183Arguments:
1184 s SSL* of the current session
1185 ad unknown (part of OpenSSL API) (unused)
1186 arg Callback of "our" registered data
1187
1188Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1189*/
1190
3bcbbbe2 1191#ifdef EXIM_HAVE_OPENSSL_TLSEXT
7be682ca 1192static int
7be682ca
PP
1193tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1194{
1195const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
3f7eeb86 1196tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
7be682ca 1197int rc;
3f0945ff 1198int old_pool = store_pool;
cf0c6164 1199uschar * dummy_errstr;
7be682ca
PP
1200
1201if (!servername)
1202 return SSL_TLSEXT_ERR_OK;
1203
3f0945ff 1204DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
7be682ca
PP
1205 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1206
1207/* Make the extension value available for expansion */
3f0945ff 1208store_pool = POOL_PERM;
817d9f57 1209tls_in.sni = string_copy(US servername);
3f0945ff 1210store_pool = old_pool;
7be682ca
PP
1211
1212if (!reexpand_tls_files_for_sni)
1213 return SSL_TLSEXT_ERR_OK;
1214
1215/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1216not confident that memcpy wouldn't break some internal reference counting.
1217Especially since there's a references struct member, which would be off. */
1218
0df4ab80 1219if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
7be682ca
PP
1220 {
1221 ERR_error_string(ERR_get_error(), ssl_errstring);
1222 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1223 return SSL_TLSEXT_ERR_NOACK;
1224 }
1225
1226/* Not sure how many of these are actually needed, since SSL object
1227already exists. Might even need this selfsame callback, for reneg? */
1228
817d9f57
JH
1229SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1230SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1231SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1232SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1233SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1234SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
038597d2 1235
cf0c6164
JH
1236if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1237 || !init_ecdh(server_sni, NULL, &dummy_errstr)
038597d2
PP
1238 )
1239 return SSL_TLSEXT_ERR_NOACK;
1240
7be682ca 1241if (cbinfo->server_cipher_list)
817d9f57 1242 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
f2de3a33 1243#ifndef DISABLE_OCSP
f5d78688 1244if (cbinfo->u_ocsp.server.file)
3f7eeb86 1245 {
f5d78688 1246 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
14c7b357 1247 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
3f7eeb86
PP
1248 }
1249#endif
7be682ca 1250
c3033f13 1251if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
cf0c6164 1252 verify_callback_server, &dummy_errstr)) != OK)
c3033f13 1253 return SSL_TLSEXT_ERR_NOACK;
7be682ca 1254
3f7eeb86
PP
1255/* do this after setup_certs, because this can require the certs for verifying
1256OCSP information. */
cf0c6164 1257if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
0df4ab80 1258 return SSL_TLSEXT_ERR_NOACK;
a799883d 1259
7be682ca 1260DEBUG(D_tls) debug_printf("Switching SSL context.\n");
817d9f57 1261SSL_set_SSL_CTX(s, server_sni);
7be682ca
PP
1262
1263return SSL_TLSEXT_ERR_OK;
1264}
3bcbbbe2 1265#endif /* EXIM_HAVE_OPENSSL_TLSEXT */
7be682ca
PP
1266
1267
1268
1269
f2de3a33 1270#ifndef DISABLE_OCSP
f5d78688 1271
3f7eeb86
PP
1272/*************************************************
1273* Callback to handle OCSP Stapling *
1274*************************************************/
1275
1276/* Called when acting as server during the TLS session setup if the client
1277requests OCSP information with a Certificate Status Request.
1278
1279Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1280project.
1281
1282*/
1283
1284static int
f5d78688 1285tls_server_stapling_cb(SSL *s, void *arg)
3f7eeb86
PP
1286{
1287const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
47195144 1288uschar *response_der; /*XXX blob */
3f7eeb86
PP
1289int response_der_len;
1290
47195144
JH
1291/*XXX stack: use SSL_get_certificate() to see which cert; from that work
1292out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1293buggy in current OpenSSL; it returns the last cert loaded always rather than
1294the one actually presented. So we can't support a stack of OCSP proofs at
1295this time. */
1296
af4a1bca 1297DEBUG(D_tls)
b3ef41c9 1298 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
f5d78688
JH
1299 cbinfo->u_ocsp.server.response ? "have" : "lack");
1300
44662487 1301tls_in.ocsp = OCSP_NOT_RESP;
f5d78688 1302if (!cbinfo->u_ocsp.server.response)
3f7eeb86
PP
1303 return SSL_TLSEXT_ERR_NOACK;
1304
1305response_der = NULL;
47195144 1306response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
44662487 1307 &response_der);
3f7eeb86
PP
1308if (response_der_len <= 0)
1309 return SSL_TLSEXT_ERR_NOACK;
1310
5e55c7a9 1311SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
44662487 1312tls_in.ocsp = OCSP_VFIED;
3f7eeb86
PP
1313return SSL_TLSEXT_ERR_OK;
1314}
1315
3f7eeb86 1316
f5d78688
JH
1317static void
1318time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1319{
1320BIO_printf(bp, "\t%s: ", str);
1321ASN1_GENERALIZEDTIME_print(bp, time);
1322BIO_puts(bp, "\n");
1323}
1324
1325static int
1326tls_client_stapling_cb(SSL *s, void *arg)
1327{
1328tls_ext_ctx_cb * cbinfo = arg;
1329const unsigned char * p;
1330int len;
1331OCSP_RESPONSE * rsp;
1332OCSP_BASICRESP * bs;
1333int i;
1334
1335DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1336len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1337if(!p)
1338 {
44662487 1339 /* Expect this when we requested ocsp but got none */
6c6d6e48 1340 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
44662487 1341 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
f5d78688
JH
1342 else
1343 DEBUG(D_tls) debug_printf(" null\n");
44662487 1344 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688 1345 }
018058b2 1346
f5d78688
JH
1347if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1348 {
018058b2 1349 tls_out.ocsp = OCSP_FAILED;
6c6d6e48 1350 if (LOGGING(tls_cipher))
1eca31ca 1351 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
f5d78688
JH
1352 else
1353 DEBUG(D_tls) debug_printf(" parse error\n");
1354 return 0;
1355 }
1356
1357if(!(bs = OCSP_response_get1_basic(rsp)))
1358 {
018058b2 1359 tls_out.ocsp = OCSP_FAILED;
6c6d6e48 1360 if (LOGGING(tls_cipher))
1eca31ca 1361 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
f5d78688
JH
1362 else
1363 DEBUG(D_tls) debug_printf(" error parsing response\n");
1364 OCSP_RESPONSE_free(rsp);
1365 return 0;
1366 }
1367
1368/* We'd check the nonce here if we'd put one in the request. */
1369/* However that would defeat cacheability on the server so we don't. */
1370
f5d78688
JH
1371/* This section of code reworked from OpenSSL apps source;
1372 The OpenSSL Project retains copyright:
1373 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1374*/
1375 {
1376 BIO * bp = NULL;
f5d78688
JH
1377 int status, reason;
1378 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1379
57887ecc 1380 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
f5d78688
JH
1381
1382 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1383
1384 /* Use the chain that verified the server cert to verify the stapled info */
1385 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1386
c3033f13 1387 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
44662487 1388 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
f5d78688 1389 {
018058b2 1390 tls_out.ocsp = OCSP_FAILED;
57887ecc
JH
1391 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1392 "Received TLS cert status response, itself unverifiable: %s",
1393 ERR_reason_error_string(ERR_peek_error()));
f5d78688
JH
1394 BIO_printf(bp, "OCSP response verify failure\n");
1395 ERR_print_errors(bp);
57887ecc 1396 OCSP_RESPONSE_print(bp, rsp, 0);
c8dfb21d 1397 goto failed;
f5d78688
JH
1398 }
1399
1400 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1401
c8dfb21d
JH
1402 /*XXX So we have a good stapled OCSP status. How do we know
1403 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1404 OCSP_resp_find_status() which matches on a cert id, which presumably
1405 we should use. Making an id needs OCSP_cert_id_new(), which takes
1406 issuerName, issuerKey, serialNumber. Are they all in the cert?
1407
1408 For now, carry on blindly accepting the resp. */
1409
f5d78688 1410 {
f5d78688
JH
1411 OCSP_SINGLERESP * single;
1412
c8dfb21d
JH
1413#ifdef EXIM_HAVE_OCSP_RESP_COUNT
1414 if (OCSP_resp_count(bs) != 1)
1415#else
1416 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
f5d78688 1417 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
c8dfb21d 1418#endif
f5d78688 1419 {
018058b2 1420 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1421 log_write(0, LOG_MAIN, "OCSP stapling "
1422 "with multiple responses not handled");
c8dfb21d 1423 goto failed;
f5d78688
JH
1424 }
1425 single = OCSP_resp_get0(bs, 0);
44662487
JH
1426 status = OCSP_single_get0_status(single, &reason, &rev,
1427 &thisupd, &nextupd);
f5d78688
JH
1428 }
1429
f5d78688
JH
1430 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1431 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
44662487
JH
1432 if (!OCSP_check_validity(thisupd, nextupd,
1433 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
f5d78688 1434 {
018058b2 1435 tls_out.ocsp = OCSP_FAILED;
f5d78688
JH
1436 DEBUG(D_tls) ERR_print_errors(bp);
1437 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
f5d78688 1438 }
44662487 1439 else
f5d78688 1440 {
44662487
JH
1441 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1442 OCSP_cert_status_str(status));
1443 switch(status)
1444 {
1445 case V_OCSP_CERTSTATUS_GOOD:
44662487 1446 tls_out.ocsp = OCSP_VFIED;
018058b2 1447 i = 1;
c8dfb21d 1448 goto good;
44662487 1449 case V_OCSP_CERTSTATUS_REVOKED:
018058b2 1450 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1451 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1452 reason != -1 ? "; reason: " : "",
1453 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1454 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
44662487
JH
1455 break;
1456 default:
018058b2 1457 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1458 log_write(0, LOG_MAIN,
1459 "Server certificate status unknown, in OCSP stapling");
44662487
JH
1460 break;
1461 }
f5d78688 1462 }
c8dfb21d
JH
1463 failed:
1464 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1465 good:
f5d78688
JH
1466 BIO_free(bp);
1467 }
1468
1469OCSP_RESPONSE_free(rsp);
1470return i;
1471}
f2de3a33 1472#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
1473
1474
7be682ca 1475/*************************************************
059ec3d9
PH
1476* Initialize for TLS *
1477*************************************************/
1478
e51c7be2
JH
1479/* Called from both server and client code, to do preliminary initialization
1480of the library. We allocate and return a context structure.
059ec3d9
PH
1481
1482Arguments:
946ecbe0 1483 ctxp returned SSL context
059ec3d9
PH
1484 host connected host, if client; NULL if server
1485 dhparam DH parameter file
1486 certificate certificate file
1487 privatekey private key
f5d78688 1488 ocsp_file file of stapling info (server); flag for require ocsp (client)
059ec3d9 1489 addr address if client; NULL if server (for some randomness)
946ecbe0 1490 cbp place to put allocated callback context
cf0c6164 1491 errstr error string pointer
059ec3d9
PH
1492
1493Returns: OK/DEFER/FAIL
1494*/
1495
1496static int
817d9f57 1497tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
3f7eeb86 1498 uschar *privatekey,
f2de3a33 1499#ifndef DISABLE_OCSP
47195144 1500 uschar *ocsp_file, /*XXX stack, in server*/
3f7eeb86 1501#endif
cf0c6164 1502 address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr)
059ec3d9 1503{
7006ee24 1504SSL_CTX * ctx;
77bb000f 1505long init_options;
7be682ca 1506int rc;
a7538db1 1507tls_ext_ctx_cb * cbinfo;
7be682ca
PP
1508
1509cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1510cbinfo->certificate = certificate;
1511cbinfo->privatekey = privatekey;
a6510420 1512cbinfo->is_server = host==NULL;
f2de3a33 1513#ifndef DISABLE_OCSP
c3033f13 1514cbinfo->verify_stack = NULL;
a6510420 1515if (!host)
f5d78688
JH
1516 {
1517 cbinfo->u_ocsp.server.file = ocsp_file;
1518 cbinfo->u_ocsp.server.file_expanded = NULL;
1519 cbinfo->u_ocsp.server.response = NULL;
1520 }
1521else
1522 cbinfo->u_ocsp.client.verify_store = NULL;
3f7eeb86 1523#endif
7be682ca 1524cbinfo->dhparam = dhparam;
0df4ab80 1525cbinfo->server_cipher_list = NULL;
7be682ca 1526cbinfo->host = host;
0cbf2b82 1527#ifndef DISABLE_EVENT
a7538db1
JH
1528cbinfo->event_action = NULL;
1529#endif
77bb000f 1530
059ec3d9
PH
1531SSL_load_error_strings(); /* basic set up */
1532OpenSSL_add_ssl_algorithms();
1533
c8dfb21d 1534#ifdef EXIM_HAVE_SHA256
77bb000f 1535/* SHA256 is becoming ever more popular. This makes sure it gets added to the
a0475b69
TK
1536list of available digests. */
1537EVP_add_digest(EVP_sha256());
cf1ef1a9 1538#endif
a0475b69 1539
f0f5a555
PP
1540/* Create a context.
1541The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1542negotiation in the different methods; as far as I can tell, the only
1543*_{server,client}_method which allows negotiation is SSLv23, which exists even
1544when OpenSSL is built without SSLv2 support.
1545By disabling with openssl_options, we can let admins re-enable with the
1546existing knob. */
059ec3d9 1547
7006ee24
JH
1548if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1549 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
059ec3d9
PH
1550
1551/* It turns out that we need to seed the random number generator this early in
1552order to get the full complement of ciphers to work. It took me roughly a day
1553of work to discover this by experiment.
1554
1555On systems that have /dev/urandom, SSL may automatically seed itself from
1556there. Otherwise, we have to make something up as best we can. Double check
1557afterwards. */
1558
1559if (!RAND_status())
1560 {
1561 randstuff r;
9e3331ea 1562 gettimeofday(&r.tv, NULL);
059ec3d9
PH
1563 r.p = getpid();
1564
5903c6ff
JH
1565 RAND_seed(US (&r), sizeof(r));
1566 RAND_seed(US big_buffer, big_buffer_size);
1567 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
059ec3d9
PH
1568
1569 if (!RAND_status())
7199e1ee 1570 return tls_error(US"RAND_status", host,
cf0c6164 1571 US"unable to seed random number generator", errstr);
059ec3d9
PH
1572 }
1573
1574/* Set up the information callback, which outputs if debugging is at a suitable
1575level. */
1576
7006ee24 1577DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
059ec3d9 1578
c80c5570 1579/* Automatically re-try reads/writes after renegotiation. */
7006ee24 1580(void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
c80c5570 1581
77bb000f
PP
1582/* Apply administrator-supplied work-arounds.
1583Historically we applied just one requested option,
1584SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1585moved to an administrator-controlled list of options to specify and
1586grandfathered in the first one as the default value for "openssl_options".
059ec3d9 1587
77bb000f
PP
1588No OpenSSL version number checks: the options we accept depend upon the
1589availability of the option value macros from OpenSSL. */
059ec3d9 1590
7006ee24 1591if (!tls_openssl_options_parse(openssl_options, &init_options))
cf0c6164 1592 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
77bb000f
PP
1593
1594if (init_options)
1595 {
1596 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
7006ee24 1597 if (!(SSL_CTX_set_options(ctx, init_options)))
77bb000f 1598 return tls_error(string_sprintf(
cf0c6164 1599 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
77bb000f
PP
1600 }
1601else
1602 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
059ec3d9 1603
7006ee24
JH
1604/* Disable session cache unconditionally */
1605
1606(void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
1607
059ec3d9 1608/* Initialize with DH parameters if supplied */
10ca4f1c 1609/* Initialize ECDH temp key parameter selection */
059ec3d9 1610
7006ee24
JH
1611if ( !init_dh(ctx, dhparam, host, errstr)
1612 || !init_ecdh(ctx, host, errstr)
038597d2
PP
1613 )
1614 return DEFER;
059ec3d9 1615
3f7eeb86 1616/* Set up certificate and key (and perhaps OCSP info) */
059ec3d9 1617
7006ee24 1618if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
23bb6982 1619 return rc;
c91535f3 1620
c3033f13
JH
1621/* If we need to handle SNI or OCSP, do so */
1622
3bcbbbe2 1623#ifdef EXIM_HAVE_OPENSSL_TLSEXT
c3033f13
JH
1624# ifndef DISABLE_OCSP
1625 if (!(cbinfo->verify_stack = sk_X509_new_null()))
1626 {
1627 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
1628 return FAIL;
1629 }
1630# endif
1631
f5d78688 1632if (host == NULL) /* server */
3f0945ff 1633 {
f2de3a33 1634# ifndef DISABLE_OCSP
f5d78688 1635 /* We check u_ocsp.server.file, not server.response, because we care about if
3f7eeb86
PP
1636 the option exists, not what the current expansion might be, as SNI might
1637 change the certificate and OCSP file in use between now and the time the
1638 callback is invoked. */
f5d78688 1639 if (cbinfo->u_ocsp.server.file)
3f7eeb86 1640 {
7006ee24
JH
1641 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
1642 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
3f7eeb86 1643 }
f5d78688 1644# endif
3f0945ff
PP
1645 /* We always do this, so that $tls_sni is available even if not used in
1646 tls_certificate */
7006ee24
JH
1647 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
1648 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
3f0945ff 1649 }
f2de3a33 1650# ifndef DISABLE_OCSP
f5d78688
JH
1651else /* client */
1652 if(ocsp_file) /* wanting stapling */
1653 {
1654 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1655 {
1656 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1657 return FAIL;
1658 }
7006ee24
JH
1659 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
1660 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
f5d78688
JH
1661 }
1662# endif
7be682ca 1663#endif
059ec3d9 1664
e51c7be2 1665cbinfo->verify_cert_hostnames = NULL;
e51c7be2 1666
c8dfb21d 1667#ifdef EXIM_HAVE_EPHEM_RSA_KEX
059ec3d9 1668/* Set up the RSA callback */
7006ee24 1669SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
c8dfb21d 1670#endif
059ec3d9
PH
1671
1672/* Finally, set the timeout, and we are done */
1673
7006ee24 1674SSL_CTX_set_timeout(ctx, ssl_session_timeout);
059ec3d9 1675DEBUG(D_tls) debug_printf("Initialized TLS\n");
7be682ca 1676
817d9f57 1677*cbp = cbinfo;
7006ee24 1678*ctxp = ctx;
7be682ca 1679
059ec3d9
PH
1680return OK;
1681}
1682
1683
1684
1685
1686/*************************************************
1687* Get name of cipher in use *
1688*************************************************/
1689
817d9f57 1690/*
059ec3d9 1691Argument: pointer to an SSL structure for the connection
817d9f57
JH
1692 buffer to use for answer
1693 size of buffer
1694 pointer to number of bits for cipher
059ec3d9
PH
1695Returns: nothing
1696*/
1697
1698static void
817d9f57 1699construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
059ec3d9 1700{
57b3a7f5
PP
1701/* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1702yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1703the accessor functions use const in the prototype. */
1704const SSL_CIPHER *c;
d9784128 1705const uschar *ver;
059ec3d9 1706
d9784128 1707ver = (const uschar *)SSL_get_version(ssl);
059ec3d9 1708
57b3a7f5 1709c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1710SSL_CIPHER_get_bits(c, bits);
059ec3d9 1711
817d9f57
JH
1712string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1713 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1714
1715DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1716}
1717
1718
f69979cf
JH
1719static void
1720peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1721{
1722/*XXX we might consider a list-of-certs variable for the cert chain.
1723SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1724in list-handling functions, also consider the difference between the entire
1725chain and the elements sent by the peer. */
1726
1727/* Will have already noted peercert on a verify fail; possibly not the leaf */
1728if (!tlsp->peercert)
1729 tlsp->peercert = SSL_get_peer_certificate(ssl);
1730/* Beware anonymous ciphers which lead to server_cert being NULL */
1731if (tlsp->peercert)
1732 {
1733 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1734 peerdn[bsize-1] = '\0';
1735 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1736 }
1737else
1738 tlsp->peerdn = NULL;
1739}
1740
1741
059ec3d9
PH
1742
1743
1744
1745/*************************************************
1746* Set up for verifying certificates *
1747*************************************************/
1748
c3033f13
JH
1749/* Load certs from file, return TRUE on success */
1750
1751static BOOL
1752chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
1753{
1754BIO * bp;
1755X509 * x;
1756
1757if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
1758while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
1759 sk_X509_push(verify_stack, x);
1760BIO_free(bp);
1761return TRUE;
1762}
1763
1764
1765
059ec3d9
PH
1766/* Called by both client and server startup
1767
1768Arguments:
7be682ca 1769 sctx SSL_CTX* to initialise
059ec3d9
PH
1770 certs certs file or NULL
1771 crl CRL file or NULL
1772 host NULL in a server; the remote host in a client
1773 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1774 otherwise passed as FALSE
983207c1 1775 cert_vfy_cb Callback function for certificate verification
cf0c6164 1776 errstr error string pointer
059ec3d9
PH
1777
1778Returns: OK/DEFER/FAIL
1779*/
1780
1781static int
983207c1 1782setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
cf0c6164 1783 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
059ec3d9
PH
1784{
1785uschar *expcerts, *expcrl;
1786
cf0c6164 1787if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
059ec3d9 1788 return DEFER;
57cc2785 1789DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
059ec3d9 1790
10a831a3 1791if (expcerts && *expcerts)
059ec3d9 1792 {
10a831a3
JH
1793 /* Tell the library to use its compiled-in location for the system default
1794 CA bundle. Then add the ones specified in the config, if any. */
cb1d7830 1795
10a831a3 1796 if (!SSL_CTX_set_default_verify_paths(sctx))
cf0c6164 1797 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
10a831a3
JH
1798
1799 if (Ustrcmp(expcerts, "system") != 0)
059ec3d9 1800 {
cb1d7830
JH
1801 struct stat statbuf;
1802
cb1d7830
JH
1803 if (Ustat(expcerts, &statbuf) < 0)
1804 {
1805 log_write(0, LOG_MAIN|LOG_PANIC,
1806 "failed to stat %s for certificates", expcerts);
1807 return DEFER;
1808 }
059ec3d9 1809 else
059ec3d9 1810 {
cb1d7830
JH
1811 uschar *file, *dir;
1812 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1813 { file = NULL; dir = expcerts; }
1814 else
c3033f13
JH
1815 {
1816 file = expcerts; dir = NULL;
1817#ifndef DISABLE_OCSP
1818 /* In the server if we will be offering an OCSP proof, load chain from
1819 file for verifying the OCSP proof at load time. */
1820
1821 if ( !host
1822 && statbuf.st_size > 0
1823 && server_static_cbinfo->u_ocsp.server.file
1824 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
1825 )
1826 {
1827 log_write(0, LOG_MAIN|LOG_PANIC,
57887ecc 1828 "failed to load cert chain from %s", file);
c3033f13
JH
1829 return DEFER;
1830 }
1831#endif
1832 }
cb1d7830
JH
1833
1834 /* If a certificate file is empty, the next function fails with an
1835 unhelpful error message. If we skip it, we get the correct behaviour (no
1836 certificates are recognized, but the error message is still misleading (it
c3033f13 1837 says no certificate was supplied). But this is better. */
cb1d7830 1838
f2f2c91b
JH
1839 if ( (!file || statbuf.st_size > 0)
1840 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
cf0c6164 1841 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
cb1d7830
JH
1842
1843 /* Load the list of CAs for which we will accept certs, for sending
1844 to the client. This is only for the one-file tls_verify_certificates
1845 variant.
1846 If a list isn't loaded into the server, but
1847 some verify locations are set, the server end appears to make
4c04137d 1848 a wildcard request for client certs.
10a831a3 1849 Meanwhile, the client library as default behaviour *ignores* the list
cb1d7830
JH
1850 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1851 Because of this, and that the dir variant is likely only used for
1852 the public-CA bundle (not for a private CA), not worth fixing.
1853 */
f2f2c91b 1854 if (file)
cb1d7830
JH
1855 {
1856 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
f2f2c91b
JH
1857
1858 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
cb1d7830
JH
1859 sk_X509_NAME_num(names));
1860 SSL_CTX_set_client_CA_list(sctx, names);
1861 }
059ec3d9
PH
1862 }
1863 }
1864
1865 /* Handle a certificate revocation list. */
1866
10a831a3 1867#if OPENSSL_VERSION_NUMBER > 0x00907000L
059ec3d9 1868
8b417f2c 1869 /* This bit of code is now the version supplied by Lars Mainka. (I have
10a831a3 1870 merely reformatted it into the Exim code style.)
8b417f2c 1871
10a831a3
JH
1872 "From here I changed the code to add support for multiple crl's
1873 in pem format in one file or to support hashed directory entries in
1874 pem format instead of a file. This method now uses the library function
1875 X509_STORE_load_locations to add the CRL location to the SSL context.
1876 OpenSSL will then handle the verify against CA certs and CRLs by
1877 itself in the verify callback." */
8b417f2c 1878
cf0c6164 1879 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
10a831a3 1880 if (expcrl && *expcrl)
059ec3d9 1881 {
8b417f2c
PH
1882 struct stat statbufcrl;
1883 if (Ustat(expcrl, &statbufcrl) < 0)
1884 {
1885 log_write(0, LOG_MAIN|LOG_PANIC,
1886 "failed to stat %s for certificates revocation lists", expcrl);
1887 return DEFER;
1888 }
1889 else
059ec3d9 1890 {
8b417f2c
PH
1891 /* is it a file or directory? */
1892 uschar *file, *dir;
7be682ca 1893 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1894 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1895 {
8b417f2c
PH
1896 file = NULL;
1897 dir = expcrl;
1898 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1899 }
1900 else
1901 {
8b417f2c
PH
1902 file = expcrl;
1903 dir = NULL;
1904 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1905 }
8b417f2c 1906 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
cf0c6164 1907 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
8b417f2c
PH
1908
1909 /* setting the flags to check against the complete crl chain */
1910
1911 X509_STORE_set_flags(cvstore,
1912 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1913 }
059ec3d9
PH
1914 }
1915
10a831a3 1916#endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
059ec3d9
PH
1917
1918 /* If verification is optional, don't fail if no certificate */
1919
7be682ca 1920 SSL_CTX_set_verify(sctx,
059ec3d9 1921 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1922 cert_vfy_cb);
059ec3d9
PH
1923 }
1924
1925return OK;
1926}
1927
1928
1929
1930/*************************************************
1931* Start a TLS session in a server *
1932*************************************************/
1933
1934/* This is called when Exim is running as a server, after having received
1935the STARTTLS command. It must respond to that command, and then negotiate
1936a TLS session.
1937
1938Arguments:
1939 require_ciphers allowed ciphers
cf0c6164 1940 errstr pointer to error message
059ec3d9
PH
1941
1942Returns: OK on success
1943 DEFER for errors before the start of the negotiation
4c04137d 1944 FAIL for errors during the negotiation; the server can't
059ec3d9
PH
1945 continue running.
1946*/
1947
1948int
cf0c6164 1949tls_server_start(const uschar * require_ciphers, uschar ** errstr)
059ec3d9
PH
1950{
1951int rc;
cf0c6164
JH
1952uschar * expciphers;
1953tls_ext_ctx_cb * cbinfo;
f69979cf 1954static uschar peerdn[256];
817d9f57 1955static uschar cipherbuf[256];
059ec3d9
PH
1956
1957/* Check for previous activation */
1958
817d9f57 1959if (tls_in.active >= 0)
059ec3d9 1960 {
cf0c6164 1961 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
925ac8e4 1962 smtp_printf("554 Already in TLS\r\n", FALSE);
059ec3d9
PH
1963 return FAIL;
1964 }
1965
1966/* Initialize the SSL library. If it fails, it will already have logged
1967the error. */
1968
817d9f57 1969rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
f2de3a33 1970#ifndef DISABLE_OCSP
47195144 1971 tls_ocsp_file, /*XXX stack*/
3f7eeb86 1972#endif
cf0c6164 1973 NULL, &server_static_cbinfo, errstr);
059ec3d9 1974if (rc != OK) return rc;
817d9f57 1975cbinfo = server_static_cbinfo;
059ec3d9 1976
cf0c6164 1977if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
059ec3d9
PH
1978 return FAIL;
1979
1980/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1981were historically separated by underscores. So that I can use either form in my
1982tests, and also for general convenience, we turn underscores into hyphens here.
1983*/
059ec3d9 1984
c3033f13 1985if (expciphers)
059ec3d9 1986 {
c3033f13 1987 uschar * s = expciphers;
059ec3d9
PH
1988 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1989 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1990 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
cf0c6164 1991 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
7be682ca 1992 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1993 }
1994
1995/* If this is a host for which certificate verification is mandatory or
1996optional, set up appropriately. */
1997
817d9f57 1998tls_in.certificate_verified = FALSE;
c0635b6d 1999#ifdef SUPPORT_DANE
53a7196b
JH
2000tls_in.dane_verified = FALSE;
2001#endif
a2ff477a 2002server_verify_callback_called = FALSE;
059ec3d9
PH
2003
2004if (verify_check_host(&tls_verify_hosts) == OK)
2005 {
983207c1 2006 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
cf0c6164 2007 FALSE, verify_callback_server, errstr);
059ec3d9 2008 if (rc != OK) return rc;
a2ff477a 2009 server_verify_optional = FALSE;
059ec3d9
PH
2010 }
2011else if (verify_check_host(&tls_try_verify_hosts) == OK)
2012 {
983207c1 2013 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
cf0c6164 2014 TRUE, verify_callback_server, errstr);
059ec3d9 2015 if (rc != OK) return rc;
a2ff477a 2016 server_verify_optional = TRUE;
059ec3d9
PH
2017 }
2018
2019/* Prepare for new connection */
2020
cf0c6164
JH
2021if (!(server_ssl = SSL_new(server_ctx)))
2022 return tls_error(US"SSL_new", NULL, NULL, errstr);
da3ad30d
PP
2023
2024/* Warning: we used to SSL_clear(ssl) here, it was removed.
2025 *
2026 * With the SSL_clear(), we get strange interoperability bugs with
2027 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2028 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2029 *
2030 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2031 * session shutdown. In this case, we have a brand new object and there's no
2032 * obvious reason to immediately clear it. I'm guessing that this was
2033 * originally added because of incomplete initialisation which the clear fixed,
2034 * in some historic release.
2035 */
059ec3d9
PH
2036
2037/* Set context and tell client to go ahead, except in the case of TLS startup
2038on connection, where outputting anything now upsets the clients and tends to
2039make them disconnect. We need to have an explicit fflush() here, to force out
2040the response. Other smtp_printf() calls do not need it, because in non-TLS
2041mode, the fflush() happens when smtp_getc() is called. */
2042
817d9f57
JH
2043SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2044if (!tls_in.on_connect)
059ec3d9 2045 {
925ac8e4 2046 smtp_printf("220 TLS go ahead\r\n", FALSE);
059ec3d9
PH
2047 fflush(smtp_out);
2048 }
2049
2050/* Now negotiate the TLS session. We put our own timer on it, since it seems
2051that the OpenSSL library doesn't. */
2052
817d9f57
JH
2053SSL_set_wfd(server_ssl, fileno(smtp_out));
2054SSL_set_rfd(server_ssl, fileno(smtp_in));
2055SSL_set_accept_state(server_ssl);
059ec3d9
PH
2056
2057DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2058
2059sigalrm_seen = FALSE;
2060if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 2061rc = SSL_accept(server_ssl);
059ec3d9
PH
2062alarm(0);
2063
2064if (rc <= 0)
2065 {
cf0c6164 2066 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
059ec3d9
PH
2067 return FAIL;
2068 }
2069
2070DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2071
2072/* TLS has been set up. Adjust the input functions to read via TLS,
2073and initialize things. */
2074
f69979cf
JH
2075peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2076
817d9f57
JH
2077construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
2078tls_in.cipher = cipherbuf;
059ec3d9
PH
2079
2080DEBUG(D_tls)
2081 {
2082 uschar buf[2048];
817d9f57 2083 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
2084 debug_printf("Shared ciphers: %s\n", buf);
2085 }
2086
9d1c15ef
JH
2087/* Record the certificate we presented */
2088 {
2089 X509 * crt = SSL_get_certificate(server_ssl);
2090 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2091 }
059ec3d9 2092
817d9f57
JH
2093/* Only used by the server-side tls (tls_in), including tls_getc.
2094 Client-side (tls_out) reads (seem to?) go via
2095 smtp_read_response()/ip_recv().
2096 Hence no need to duplicate for _in and _out.
2097 */
b808677c 2098if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
059ec3d9
PH
2099ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2100ssl_xfer_eof = ssl_xfer_error = 0;
2101
2102receive_getc = tls_getc;
0d81dabc 2103receive_getbuf = tls_getbuf;
584e96c6 2104receive_get_cache = tls_get_cache;
059ec3d9
PH
2105receive_ungetc = tls_ungetc;
2106receive_feof = tls_feof;
2107receive_ferror = tls_ferror;
58eb016e 2108receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 2109
817d9f57 2110tls_in.active = fileno(smtp_out);
059ec3d9
PH
2111return OK;
2112}
2113
2114
2115
2116
043b1248
JH
2117static int
2118tls_client_basic_ctx_init(SSL_CTX * ctx,
cf0c6164
JH
2119 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2120 uschar ** errstr)
043b1248
JH
2121{
2122int rc;
94431adb 2123/* stick to the old behaviour for compatibility if tls_verify_certificates is
043b1248
JH
2124 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2125 the specified host patterns if one of them is defined */
2126
610ff438
JH
2127if ( ( !ob->tls_verify_hosts
2128 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2129 )
5130845b 2130 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
aa2a70ba 2131 )
043b1248 2132 client_verify_optional = FALSE;
5130845b 2133else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
aa2a70ba
JH
2134 client_verify_optional = TRUE;
2135else
2136 return OK;
2137
2138if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
cf0c6164
JH
2139 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2140 errstr)) != OK)
aa2a70ba 2141 return rc;
043b1248 2142
5130845b 2143if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
043b1248 2144 {
4af0d74a 2145 cbinfo->verify_cert_hostnames =
8c5d388a 2146#ifdef SUPPORT_I18N
4af0d74a
JH
2147 string_domain_utf8_to_alabel(host->name, NULL);
2148#else
2149 host->name;
2150#endif
aa2a70ba
JH
2151 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2152 cbinfo->verify_cert_hostnames);
043b1248 2153 }
043b1248
JH
2154return OK;
2155}
059ec3d9 2156
fde080a4 2157
c0635b6d 2158#ifdef SUPPORT_DANE
fde080a4 2159static int
cf0c6164 2160dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
fde080a4
JH
2161{
2162dns_record * rr;
2163dns_scan dnss;
2164const char * hostnames[2] = { CS host->name, NULL };
2165int found = 0;
2166
2167if (DANESSL_init(ssl, NULL, hostnames) != 1)
cf0c6164 2168 return tls_error(US"hostnames load", host, NULL, errstr);
fde080a4
JH
2169
2170for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
2171 rr;
2172 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2173 ) if (rr->type == T_TLSA)
2174 {
c3033f13 2175 const uschar * p = rr->data;
fde080a4
JH
2176 uint8_t usage, selector, mtype;
2177 const char * mdname;
2178
fde080a4 2179 usage = *p++;
133d2546
JH
2180
2181 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2182 if (usage != 2 && usage != 3) continue;
2183
fde080a4
JH
2184 selector = *p++;
2185 mtype = *p++;
2186
2187 switch (mtype)
2188 {
133d2546
JH
2189 default: continue; /* Only match-types 0, 1, 2 are supported */
2190 case 0: mdname = NULL; break;
2191 case 1: mdname = "sha256"; break;
2192 case 2: mdname = "sha512"; break;
fde080a4
JH
2193 }
2194
133d2546 2195 found++;
fde080a4
JH
2196 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2197 {
2198 default:
cf0c6164 2199 return tls_error(US"tlsa load", host, NULL, errstr);
c035b645 2200 case 0: /* action not taken */
fde080a4
JH
2201 case 1: break;
2202 }
594706ea
JH
2203
2204 tls_out.tlsa_usage |= 1<<usage;
fde080a4
JH
2205 }
2206
2207if (found)
2208 return OK;
2209
133d2546 2210log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
6ebd79ec 2211return DEFER;
fde080a4 2212}
c0635b6d 2213#endif /*SUPPORT_DANE*/
fde080a4
JH
2214
2215
2216
059ec3d9
PH
2217/*************************************************
2218* Start a TLS session in a client *
2219*************************************************/
2220
2221/* Called from the smtp transport after STARTTLS has been accepted.
2222
2223Argument:
2224 fd the fd of the connection
2225 host connected host (for messages)
83da1223 2226 addr the first address
a7538db1 2227 tb transport (always smtp)
0e66b3b6 2228 tlsa_dnsa tlsa lookup, if DANE, else null
cf0c6164 2229 errstr error string pointer
059ec3d9
PH
2230
2231Returns: OK on success
2232 FAIL otherwise - note that tls_error() will not give DEFER
2233 because this is not a server
2234*/
2235
2236int
f5d78688 2237tls_client_start(int fd, host_item *host, address_item *addr,
cf0c6164 2238 transport_instance * tb,
c0635b6d 2239#ifdef SUPPORT_DANE
cf0c6164 2240 dns_answer * tlsa_dnsa,
0e66b3b6 2241#endif
cf0c6164 2242 uschar ** errstr)
059ec3d9 2243{
a7538db1
JH
2244smtp_transport_options_block * ob =
2245 (smtp_transport_options_block *)tb->options_block;
f69979cf 2246static uschar peerdn[256];
868f5672 2247uschar * expciphers;
059ec3d9 2248int rc;
817d9f57 2249static uschar cipherbuf[256];
043b1248
JH
2250
2251#ifndef DISABLE_OCSP
043b1248 2252BOOL request_ocsp = FALSE;
6634ac8d 2253BOOL require_ocsp = FALSE;
043b1248 2254#endif
043b1248 2255
c0635b6d 2256#ifdef SUPPORT_DANE
594706ea 2257tls_out.tlsa_usage = 0;
043b1248
JH
2258#endif
2259
f2de3a33 2260#ifndef DISABLE_OCSP
043b1248 2261 {
c0635b6d 2262# ifdef SUPPORT_DANE
4f59c424
JH
2263 if ( tlsa_dnsa
2264 && ob->hosts_request_ocsp[0] == '*'
2265 && ob->hosts_request_ocsp[1] == '\0'
2266 )
2267 {
2268 /* Unchanged from default. Use a safer one under DANE */
2269 request_ocsp = TRUE;
2270 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2271 " {= {4}{$tls_out_tlsa_usage}} } "
2272 " {*}{}}";
2273 }
2274# endif
2275
5130845b
JH
2276 if ((require_ocsp =
2277 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
fca41d5a
JH
2278 request_ocsp = TRUE;
2279 else
c0635b6d 2280# ifdef SUPPORT_DANE
4f59c424 2281 if (!request_ocsp)
fca41d5a 2282# endif
5130845b
JH
2283 request_ocsp =
2284 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
043b1248 2285 }
f5d78688 2286#endif
059ec3d9 2287
65867078
JH
2288rc = tls_init(&client_ctx, host, NULL,
2289 ob->tls_certificate, ob->tls_privatekey,
f2de3a33 2290#ifndef DISABLE_OCSP
44662487 2291 (void *)(long)request_ocsp,
3f7eeb86 2292#endif
cf0c6164 2293 addr, &client_static_cbinfo, errstr);
059ec3d9
PH
2294if (rc != OK) return rc;
2295
817d9f57 2296tls_out.certificate_verified = FALSE;
a2ff477a 2297client_verify_callback_called = FALSE;
059ec3d9 2298
65867078 2299if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
cf0c6164 2300 &expciphers, errstr))
059ec3d9
PH
2301 return FAIL;
2302
2303/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2304are separated by underscores. So that I can use either form in my tests, and
2305also for general convenience, we turn underscores into hyphens here. */
2306
cf0c6164 2307if (expciphers)
059ec3d9
PH
2308 {
2309 uschar *s = expciphers;
cf0c6164 2310 while (*s) { if (*s == '_') *s = '-'; s++; }
059ec3d9 2311 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 2312 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
cf0c6164 2313 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
059ec3d9
PH
2314 }
2315
c0635b6d 2316#ifdef SUPPORT_DANE
0e66b3b6 2317if (tlsa_dnsa)
a63be306 2318 {
02af313d
JH
2319 SSL_CTX_set_verify(client_ctx,
2320 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2321 verify_callback_client_dane);
e5cccda9 2322
043b1248 2323 if (!DANESSL_library_init())
cf0c6164 2324 return tls_error(US"library init", host, NULL, errstr);
043b1248 2325 if (DANESSL_CTX_init(client_ctx) <= 0)
cf0c6164 2326 return tls_error(US"context init", host, NULL, errstr);
043b1248
JH
2327 }
2328else
e51c7be2 2329
043b1248
JH
2330#endif
2331
cf0c6164
JH
2332 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob,
2333 client_static_cbinfo, errstr)) != OK)
65867078 2334 return rc;
059ec3d9 2335
65867078 2336if ((client_ssl = SSL_new(client_ctx)) == NULL)
cf0c6164 2337 return tls_error(US"SSL_new", host, NULL, errstr);
817d9f57
JH
2338SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
2339SSL_set_fd(client_ssl, fd);
2340SSL_set_connect_state(client_ssl);
059ec3d9 2341
65867078 2342if (ob->tls_sni)
3f0945ff 2343 {
cf0c6164 2344 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni, errstr))
3f0945ff 2345 return FAIL;
cf0c6164 2346 if (!tls_out.sni)
2c9a0e86
PP
2347 {
2348 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2349 }
ec4b68e5 2350 else if (!Ustrlen(tls_out.sni))
817d9f57 2351 tls_out.sni = NULL;
3f0945ff
PP
2352 else
2353 {
35731706 2354#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
2355 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
2356 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706 2357#else
66802652 2358 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
02d9264f 2359 tls_out.sni);
35731706 2360#endif
3f0945ff
PP
2361 }
2362 }
2363
c0635b6d 2364#ifdef SUPPORT_DANE
0e66b3b6 2365if (tlsa_dnsa)
cf0c6164 2366 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa, errstr)) != OK)
594706ea
JH
2367 return rc;
2368#endif
2369
f2de3a33 2370#ifndef DISABLE_OCSP
f5d78688
JH
2371/* Request certificate status at connection-time. If the server
2372does OCSP stapling we will get the callback (set in tls_init()) */
c0635b6d 2373# ifdef SUPPORT_DANE
44662487
JH
2374if (request_ocsp)
2375 {
594706ea 2376 const uschar * s;
41afb5cb
JH
2377 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
2378 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
594706ea
JH
2379 )
2380 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2381 this means we avoid the OCSP request, we wasted the setup
2382 cost in tls_init(). */
5130845b
JH
2383 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
2384 request_ocsp = require_ocsp
2385 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
594706ea
JH
2386 }
2387 }
b50c8b84
JH
2388# endif
2389
594706ea
JH
2390if (request_ocsp)
2391 {
f5d78688 2392 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
44662487
JH
2393 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
2394 tls_out.ocsp = OCSP_NOT_RESP;
2395 }
f5d78688
JH
2396#endif
2397
0cbf2b82 2398#ifndef DISABLE_EVENT
774ef2d7 2399client_static_cbinfo->event_action = tb->event_action;
a7538db1 2400#endif
043b1248 2401
059ec3d9
PH
2402/* There doesn't seem to be a built-in timeout on connection. */
2403
2404DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
2405sigalrm_seen = FALSE;
65867078 2406alarm(ob->command_timeout);
817d9f57 2407rc = SSL_connect(client_ssl);
059ec3d9
PH
2408alarm(0);
2409
c0635b6d 2410#ifdef SUPPORT_DANE
0e66b3b6 2411if (tlsa_dnsa)
fde080a4 2412 DANESSL_cleanup(client_ssl);
043b1248
JH
2413#endif
2414
059ec3d9 2415if (rc <= 0)
cf0c6164
JH
2416 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL,
2417 errstr);
059ec3d9
PH
2418
2419DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2420
f69979cf 2421peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
059ec3d9 2422
817d9f57
JH
2423construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2424tls_out.cipher = cipherbuf;
059ec3d9 2425
9d1c15ef
JH
2426/* Record the certificate we presented */
2427 {
2428 X509 * crt = SSL_get_certificate(client_ssl);
2429 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2430 }
2431
817d9f57 2432tls_out.active = fd;
059ec3d9
PH
2433return OK;
2434}
2435
2436
2437
2438
2439
0d81dabc
JH
2440static BOOL
2441tls_refill(unsigned lim)
2442{
2443int error;
2444int inbytes;
2445
2446DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2447 ssl_xfer_buffer, ssl_xfer_buffer_size);
2448
2449if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2450inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
2451 MIN(ssl_xfer_buffer_size, lim));
2452error = SSL_get_error(server_ssl, inbytes);
2453alarm(0);
2454
2455/* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2456closed down, not that the socket itself has been closed down. Revert to
2457non-SSL handling. */
2458
2459if (error == SSL_ERROR_ZERO_RETURN)
2460 {
2461 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2462
2463 receive_getc = smtp_getc;
2464 receive_getbuf = smtp_getbuf;
2465 receive_get_cache = smtp_get_cache;
2466 receive_ungetc = smtp_ungetc;
2467 receive_feof = smtp_feof;
2468 receive_ferror = smtp_ferror;
2469 receive_smtp_buffered = smtp_buffered;
2470
2471 SSL_free(server_ssl);
2472 server_ssl = NULL;
2473 tls_in.active = -1;
2474 tls_in.bits = 0;
2475 tls_in.cipher = NULL;
2476 tls_in.peerdn = NULL;
2477 tls_in.sni = NULL;
2478
2479 return FALSE;
2480 }
2481
2482/* Handle genuine errors */
2483
2484else if (error == SSL_ERROR_SSL)
2485 {
2486 ERR_error_string(ERR_get_error(), ssl_errstring);
2487 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2488 ssl_xfer_error = 1;
2489 return FALSE;
2490 }
2491
2492else if (error != SSL_ERROR_NONE)
2493 {
2494 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2495 ssl_xfer_error = 1;
2496 return FALSE;
2497 }
2498
2499#ifndef DISABLE_DKIM
2500dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2501#endif
2502ssl_xfer_buffer_hwm = inbytes;
2503ssl_xfer_buffer_lwm = 0;
2504return TRUE;
2505}
2506
2507
059ec3d9
PH
2508/*************************************************
2509* TLS version of getc *
2510*************************************************/
2511
2512/* This gets the next byte from the TLS input buffer. If the buffer is empty,
2513it refills the buffer via the SSL reading function.
2514
bd8fbe36 2515Arguments: lim Maximum amount to read/buffer
059ec3d9 2516Returns: the next character or EOF
817d9f57
JH
2517
2518Only used by the server-side TLS.
059ec3d9
PH
2519*/
2520
2521int
bd8fbe36 2522tls_getc(unsigned lim)
059ec3d9
PH
2523{
2524if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
0d81dabc
JH
2525 if (!tls_refill(lim))
2526 return ssl_xfer_error ? EOF : smtp_getc(lim);
059ec3d9 2527
0d81dabc 2528/* Something in the buffer; return next uschar */
059ec3d9 2529
0d81dabc
JH
2530return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2531}
059ec3d9 2532
0d81dabc
JH
2533uschar *
2534tls_getbuf(unsigned * len)
2535{
2536unsigned size;
2537uschar * buf;
ba084640 2538
0d81dabc
JH
2539if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2540 if (!tls_refill(*len))
059ec3d9 2541 {
0d81dabc
JH
2542 if (!ssl_xfer_error) return smtp_getbuf(len);
2543 *len = 0;
2544 return NULL;
059ec3d9 2545 }
c80c5570 2546
0d81dabc
JH
2547if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
2548 size = *len;
2549buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
2550ssl_xfer_buffer_lwm += size;
2551*len = size;
2552return buf;
059ec3d9
PH
2553}
2554
0d81dabc 2555
584e96c6
JH
2556void
2557tls_get_cache()
2558{
9960d1e5 2559#ifndef DISABLE_DKIM
584e96c6
JH
2560int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
2561if (n > 0)
2562 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
584e96c6 2563#endif
9960d1e5 2564}
584e96c6 2565
059ec3d9 2566
925ac8e4
JH
2567BOOL
2568tls_could_read(void)
2569{
a5ffa9b4 2570return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
925ac8e4
JH
2571}
2572
059ec3d9
PH
2573
2574/*************************************************
2575* Read bytes from TLS channel *
2576*************************************************/
2577
2578/*
2579Arguments:
2580 buff buffer of data
2581 len size of buffer
2582
2583Returns: the number of bytes read
2584 -1 after a failed read
817d9f57
JH
2585
2586Only used by the client-side TLS.
059ec3d9
PH
2587*/
2588
2589int
389ca47a 2590tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 2591{
389ca47a 2592SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
2593int inbytes;
2594int error;
2595
389ca47a 2596DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 2597 buff, (unsigned int)len);
059ec3d9 2598
389ca47a
JH
2599inbytes = SSL_read(ssl, CS buff, len);
2600error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
2601
2602if (error == SSL_ERROR_ZERO_RETURN)
2603 {
2604 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2605 return -1;
2606 }
2607else if (error != SSL_ERROR_NONE)
059ec3d9 2608 return -1;
059ec3d9
PH
2609
2610return inbytes;
2611}
2612
2613
2614
2615
2616
2617/*************************************************
2618* Write bytes down TLS channel *
2619*************************************************/
2620
2621/*
2622Arguments:
817d9f57 2623 is_server channel specifier
059ec3d9
PH
2624 buff buffer of data
2625 len number of bytes
925ac8e4 2626 more further data expected soon
059ec3d9
PH
2627
2628Returns: the number of bytes after a successful write,
2629 -1 after a failed write
817d9f57
JH
2630
2631Used by both server-side and client-side TLS.
059ec3d9
PH
2632*/
2633
2634int
925ac8e4 2635tls_write(BOOL is_server, const uschar *buff, size_t len, BOOL more)
059ec3d9 2636{
a5ffa9b4 2637int outbytes, error, left;
817d9f57 2638SSL *ssl = is_server ? server_ssl : client_ssl;
acec9514 2639static gstring * corked = NULL;
a5ffa9b4 2640
ef698bf6 2641DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
b93be52e 2642 buff, (unsigned long)len, more ? ", more" : "");
a5ffa9b4
JH
2643
2644/* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2645"more" is notified. This hack is only ok if small amounts are involved AND only
2646one stream does it, in one context (i.e. no store reset). Currently it is used
2647for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2648
2649if (is_server && (more || corked))
2650 {
acec9514 2651 corked = string_catn(corked, buff, len);
a5ffa9b4
JH
2652 if (more)
2653 return len;
acec9514
JH
2654 buff = CUS corked->s;
2655 len = corked->ptr;
2656 corked = NULL;
a5ffa9b4 2657 }
059ec3d9 2658
a5ffa9b4 2659for (left = len; left > 0;)
059ec3d9 2660 {
c80c5570 2661 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
2662 outbytes = SSL_write(ssl, CS buff, left);
2663 error = SSL_get_error(ssl, outbytes);
2664 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2665 switch (error)
2666 {
2667 case SSL_ERROR_SSL:
96f5fe4c
JH
2668 ERR_error_string(ERR_get_error(), ssl_errstring);
2669 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2670 return -1;
059ec3d9
PH
2671
2672 case SSL_ERROR_NONE:
96f5fe4c
JH
2673 left -= outbytes;
2674 buff += outbytes;
2675 break;
059ec3d9
PH
2676
2677 case SSL_ERROR_ZERO_RETURN:
96f5fe4c
JH
2678 log_write(0, LOG_MAIN, "SSL channel closed on write");
2679 return -1;
059ec3d9 2680
817d9f57 2681 case SSL_ERROR_SYSCALL:
96f5fe4c
JH
2682 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2683 sender_fullhost ? sender_fullhost : US"<unknown>",
2684 strerror(errno));
2685 return -1;
817d9f57 2686
059ec3d9 2687 default:
96f5fe4c
JH
2688 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2689 return -1;
059ec3d9
PH
2690 }
2691 }
2692return len;
2693}
2694
2695
2696
2697/*************************************************
2698* Close down a TLS session *
2699*************************************************/
2700
2701/* This is also called from within a delivery subprocess forked from the
2702daemon, to shut down the TLS library, without actually doing a shutdown (which
2703would tamper with the SSL session in the parent process).
2704
2705Arguments: TRUE if SSL_shutdown is to be called
2706Returns: nothing
817d9f57
JH
2707
2708Used by both server-side and client-side TLS.
059ec3d9
PH
2709*/
2710
2711void
817d9f57 2712tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 2713{
817d9f57 2714SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 2715int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
2716
2717if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
2718
2719if (shutdown)
2720 {
ec8b777a 2721 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 2722 SSL_shutdown(*sslp);
059ec3d9
PH
2723 }
2724
817d9f57
JH
2725SSL_free(*sslp);
2726*sslp = NULL;
059ec3d9 2727
817d9f57 2728*fdp = -1;
059ec3d9
PH
2729}
2730
36f12725
NM
2731
2732
2733
2734/*************************************************
3375e053
PP
2735* Let tls_require_ciphers be checked at startup *
2736*************************************************/
2737
2738/* The tls_require_ciphers option, if set, must be something which the
2739library can parse.
2740
2741Returns: NULL on success, or error message
2742*/
2743
2744uschar *
2745tls_validate_require_cipher(void)
2746{
2747SSL_CTX *ctx;
2748uschar *s, *expciphers, *err;
2749
2750/* this duplicates from tls_init(), we need a better "init just global
2751state, for no specific purpose" singleton function of our own */
2752
2753SSL_load_error_strings();
2754OpenSSL_add_ssl_algorithms();
2755#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2756/* SHA256 is becoming ever more popular. This makes sure it gets added to the
2757list of available digests. */
2758EVP_add_digest(EVP_sha256());
2759#endif
2760
2761if (!(tls_require_ciphers && *tls_require_ciphers))
2762 return NULL;
2763
cf0c6164
JH
2764if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
2765 &err))
3375e053
PP
2766 return US"failed to expand tls_require_ciphers";
2767
2768if (!(expciphers && *expciphers))
2769 return NULL;
2770
2771/* normalisation ripped from above */
2772s = expciphers;
2773while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2774
2775err = NULL;
2776
2777ctx = SSL_CTX_new(SSLv23_server_method());
2778if (!ctx)
2779 {
2780 ERR_error_string(ERR_get_error(), ssl_errstring);
2781 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2782 }
2783
2784DEBUG(D_tls)
2785 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2786
2787if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2788 {
2789 ERR_error_string(ERR_get_error(), ssl_errstring);
cf0c6164
JH
2790 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
2791 expciphers, ssl_errstring);
3375e053
PP
2792 }
2793
2794SSL_CTX_free(ctx);
2795
2796return err;
2797}
2798
2799
2800
2801
2802/*************************************************
36f12725
NM
2803* Report the library versions. *
2804*************************************************/
2805
2806/* There have historically been some issues with binary compatibility in
2807OpenSSL libraries; if Exim (like many other applications) is built against
2808one version of OpenSSL but the run-time linker picks up another version,
2809it can result in serious failures, including crashing with a SIGSEGV. So
2810report the version found by the compiler and the run-time version.
2811
f64a1e23
PP
2812Note: some OS vendors backport security fixes without changing the version
2813number/string, and the version date remains unchanged. The _build_ date
2814will change, so we can more usefully assist with version diagnosis by also
2815reporting the build date.
2816
36f12725
NM
2817Arguments: a FILE* to print the results to
2818Returns: nothing
2819*/
2820
2821void
2822tls_version_report(FILE *f)
2823{
754a0503 2824fprintf(f, "Library version: OpenSSL: Compile: %s\n"
f64a1e23
PP
2825 " Runtime: %s\n"
2826 " : %s\n",
754a0503 2827 OPENSSL_VERSION_TEXT,
f64a1e23
PP
2828 SSLeay_version(SSLEAY_VERSION),
2829 SSLeay_version(SSLEAY_BUILT_ON));
2830/* third line is 38 characters for the %s and the line is 73 chars long;
2831the OpenSSL output includes a "built on: " prefix already. */
36f12725
NM
2832}
2833
9e3331ea
TK
2834
2835
2836
2837/*************************************************
17c76198 2838* Random number generation *
9e3331ea
TK
2839*************************************************/
2840
2841/* Pseudo-random number generation. The result is not expected to be
2842cryptographically strong but not so weak that someone will shoot themselves
2843in the foot using it as a nonce in input in some email header scheme or
2844whatever weirdness they'll twist this into. The result should handle fork()
2845and avoid repeating sequences. OpenSSL handles that for us.
2846
2847Arguments:
2848 max range maximum
2849Returns a random number in range [0, max-1]
2850*/
2851
2852int
17c76198 2853vaguely_random_number(int max)
9e3331ea
TK
2854{
2855unsigned int r;
2856int i, needed_len;
de6135a0
PP
2857static pid_t pidlast = 0;
2858pid_t pidnow;
9e3331ea
TK
2859uschar *p;
2860uschar smallbuf[sizeof(r)];
2861
2862if (max <= 1)
2863 return 0;
2864
de6135a0
PP
2865pidnow = getpid();
2866if (pidnow != pidlast)
2867 {
2868 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2869 is unique for each thread", this doesn't apparently apply across processes,
2870 so our own warning from vaguely_random_number_fallback() applies here too.
2871 Fix per PostgreSQL. */
2872 if (pidlast != 0)
2873 RAND_cleanup();
2874 pidlast = pidnow;
2875 }
2876
9e3331ea
TK
2877/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2878if (!RAND_status())
2879 {
2880 randstuff r;
2881 gettimeofday(&r.tv, NULL);
2882 r.p = getpid();
2883
5903c6ff 2884 RAND_seed(US (&r), sizeof(r));
9e3331ea
TK
2885 }
2886/* We're after pseudo-random, not random; if we still don't have enough data
2887in the internal PRNG then our options are limited. We could sleep and hope
2888for entropy to come along (prayer technique) but if the system is so depleted
2889in the first place then something is likely to just keep taking it. Instead,
2890we'll just take whatever little bit of pseudo-random we can still manage to
2891get. */
2892
2893needed_len = sizeof(r);
2894/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2895asked for a number less than 10. */
2896for (r = max, i = 0; r; ++i)
2897 r >>= 1;
2898i = (i + 7) / 8;
2899if (i < needed_len)
2900 needed_len = i;
2901
c8dfb21d 2902#ifdef EXIM_HAVE_RAND_PSEUDO
9e3331ea 2903/* We do not care if crypto-strong */
17c76198 2904i = RAND_pseudo_bytes(smallbuf, needed_len);
c8dfb21d
JH
2905#else
2906i = RAND_bytes(smallbuf, needed_len);
2907#endif
2908
17c76198
PP
2909if (i < 0)
2910 {
2911 DEBUG(D_all)
2912 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2913 return vaguely_random_number_fallback(max);
2914 }
2915
9e3331ea
TK
2916r = 0;
2917for (p = smallbuf; needed_len; --needed_len, ++p)
2918 {
2919 r *= 256;
2920 r += *p;
2921 }
2922
2923/* We don't particularly care about weighted results; if someone wants
2924smooth distribution and cares enough then they should submit a patch then. */
2925return r % max;
2926}
2927
77bb000f
PP
2928
2929
2930
2931/*************************************************
2932* OpenSSL option parse *
2933*************************************************/
2934
2935/* Parse one option for tls_openssl_options_parse below
2936
2937Arguments:
2938 name one option name
2939 value place to store a value for it
2940Returns success or failure in parsing
2941*/
2942
2943struct exim_openssl_option {
2944 uschar *name;
2945 long value;
2946};
2947/* We could use a macro to expand, but we need the ifdef and not all the
2948options document which version they were introduced in. Policylet: include
2949all options unless explicitly for DTLS, let the administrator choose which
2950to apply.
2951
2952This list is current as of:
e2fbf4a2
PP
2953 ==> 1.0.1b <==
2954Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2955*/
77bb000f
PP
2956static struct exim_openssl_option exim_openssl_options[] = {
2957/* KEEP SORTED ALPHABETICALLY! */
2958#ifdef SSL_OP_ALL
73a46702 2959 { US"all", SSL_OP_ALL },
77bb000f
PP
2960#endif
2961#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2962 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2963#endif
2964#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2965 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2966#endif
2967#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2968 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2969#endif
2970#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2971 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2972#endif
2973#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2974 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2975#endif
2976#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2977 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2978#endif
2979#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2980 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2981#endif
2982#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2983 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2984#endif
2985#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2986 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2987#endif
2988#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2989 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2990#endif
c80c5570
PP
2991#ifdef SSL_OP_NO_COMPRESSION
2992 { US"no_compression", SSL_OP_NO_COMPRESSION },
2993#endif
77bb000f 2994#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2995 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2996#endif
c0c7b2da
PP
2997#ifdef SSL_OP_NO_SSLv2
2998 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2999#endif
3000#ifdef SSL_OP_NO_SSLv3
3001 { US"no_sslv3", SSL_OP_NO_SSLv3 },
3002#endif
3003#ifdef SSL_OP_NO_TICKET
3004 { US"no_ticket", SSL_OP_NO_TICKET },
3005#endif
3006#ifdef SSL_OP_NO_TLSv1
3007 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
3008#endif
c80c5570
PP
3009#ifdef SSL_OP_NO_TLSv1_1
3010#if SSL_OP_NO_TLSv1_1 == 0x00000400L
3011 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
3012#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
3013#else
3014 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
3015#endif
3016#endif
3017#ifdef SSL_OP_NO_TLSv1_2
3018 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
3019#endif
e2fbf4a2
PP
3020#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
3021 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
3022#endif
77bb000f 3023#ifdef SSL_OP_SINGLE_DH_USE
73a46702 3024 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
3025#endif
3026#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 3027 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
3028#endif
3029#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 3030 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
3031#endif
3032#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 3033 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
3034#endif
3035#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 3036 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
3037#endif
3038#ifdef SSL_OP_TLS_D5_BUG
73a46702 3039 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
3040#endif
3041#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 3042 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
3043#endif
3044};
3045static int exim_openssl_options_size =
3046 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
3047
c80c5570 3048
77bb000f
PP
3049static BOOL
3050tls_openssl_one_option_parse(uschar *name, long *value)
3051{
3052int first = 0;
3053int last = exim_openssl_options_size;
3054while (last > first)
3055 {
3056 int middle = (first + last)/2;
3057 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3058 if (c == 0)
3059 {
3060 *value = exim_openssl_options[middle].value;
3061 return TRUE;
3062 }
3063 else if (c > 0)
3064 first = middle + 1;
3065 else
3066 last = middle;
3067 }
3068return FALSE;
3069}
3070
3071
3072
3073
3074/*************************************************
3075* OpenSSL option parsing logic *
3076*************************************************/
3077
3078/* OpenSSL has a number of compatibility options which an administrator might
3079reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3080we look like log_selector.
3081
3082Arguments:
3083 option_spec the administrator-supplied string of options
3084 results ptr to long storage for the options bitmap
3085Returns success or failure
3086*/
3087
3088BOOL
3089tls_openssl_options_parse(uschar *option_spec, long *results)
3090{
3091long result, item;
3092uschar *s, *end;
3093uschar keep_c;
3094BOOL adding, item_parsed;
3095
7006ee24 3096result = SSL_OP_NO_TICKET;
b1770b6e 3097/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 3098 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
3099#ifdef SSL_OP_NO_SSLv2
3100result |= SSL_OP_NO_SSLv2;
3101#endif
a57b6200
JH
3102#ifdef SSL_OP_SINGLE_DH_USE
3103result |= SSL_OP_SINGLE_DH_USE;
3104#endif
77bb000f 3105
7006ee24 3106if (!option_spec)
77bb000f
PP
3107 {
3108 *results = result;
3109 return TRUE;
3110 }
3111
3112for (s=option_spec; *s != '\0'; /**/)
3113 {
3114 while (isspace(*s)) ++s;
3115 if (*s == '\0')
3116 break;
3117 if (*s != '+' && *s != '-')
3118 {
3119 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 3120 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
3121 return FALSE;
3122 }
3123 adding = *s++ == '+';
3124 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3125 keep_c = *end;
3126 *end = '\0';
3127 item_parsed = tls_openssl_one_option_parse(s, &item);
96f5fe4c 3128 *end = keep_c;
77bb000f
PP
3129 if (!item_parsed)
3130 {
0e944a0d 3131 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
3132 return FALSE;
3133 }
3134 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3135 adding ? "adding" : "removing", result, item, s);
3136 if (adding)
3137 result |= item;
3138 else
3139 result &= ~item;
77bb000f
PP
3140 s = end;
3141 }
3142
3143*results = result;
3144return TRUE;
3145}
3146
9d1c15ef
JH
3147/* vi: aw ai sw=2
3148*/
059ec3d9 3149/* End of tls-openssl.c */