Extractors for subject-alternate-name, ocsp-uri, crl-uri return list. Bug 1358
[exim.git] / src / src / tls-openssl.c
CommitLineData
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
5a66c31b 5/* Copyright (c) University of Cambridge 1995 - 2014 */
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6/* See the file NOTICE for conditions of use and distribution. */
7
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8/* Portions Copyright (c) The OpenSSL Project 1999 */
9
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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>
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PP
25#ifdef EXPERIMENTAL_OCSP
26#include <openssl/ocsp.h>
27#endif
28
29#ifdef EXPERIMENTAL_OCSP
30#define EXIM_OCSP_SKEW_SECONDS (300L)
31#define EXIM_OCSP_MAX_AGE (-1L)
32#endif
059ec3d9 33
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34#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
35#define EXIM_HAVE_OPENSSL_TLSEXT
36#endif
37
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38/* Structure for collecting random data for seeding. */
39
40typedef struct randstuff {
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41 struct timeval tv;
42 pid_t p;
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43} randstuff;
44
45/* Local static variables */
46
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47static BOOL client_verify_callback_called = FALSE;
48static BOOL server_verify_callback_called = FALSE;
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49static const uschar *sid_ctx = US"exim";
50
d4f09789
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51/* We have three different contexts to care about.
52
53Simple case: client, `client_ctx`
54 As a client, we can be doing a callout or cut-through delivery while receiving
55 a message. So we have a client context, which should have options initialised
56 from the SMTP Transport.
57
58Server:
59 There are two cases: with and without ServerNameIndication from the client.
60 Given TLS SNI, we can be using different keys, certs and various other
61 configuration settings, because they're re-expanded with $tls_sni set. This
62 allows vhosting with TLS. This SNI is sent in the handshake.
63 A client might not send SNI, so we need a fallback, and an initial setup too.
64 So as a server, we start out using `server_ctx`.
65 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
66 `server_sni` from `server_ctx` and then initialise settings by re-expanding
67 configuration.
68*/
69
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70static SSL_CTX *client_ctx = NULL;
71static SSL_CTX *server_ctx = NULL;
72static SSL *client_ssl = NULL;
73static SSL *server_ssl = NULL;
389ca47a 74
35731706 75#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57 76static SSL_CTX *server_sni = NULL;
35731706 77#endif
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78
79static char ssl_errstring[256];
80
81static int ssl_session_timeout = 200;
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82static BOOL client_verify_optional = FALSE;
83static BOOL server_verify_optional = FALSE;
059ec3d9 84
f5d78688 85static BOOL reexpand_tls_files_for_sni = FALSE;
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86
87
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88typedef struct tls_ext_ctx_cb {
89 uschar *certificate;
90 uschar *privatekey;
3f7eeb86 91#ifdef EXPERIMENTAL_OCSP
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92 BOOL is_server;
93 union {
94 struct {
95 uschar *file;
96 uschar *file_expanded;
97 OCSP_RESPONSE *response;
98 } server;
99 struct {
100 X509_STORE *verify_store;
101 } client;
102 } u_ocsp;
3f7eeb86 103#endif
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104 uschar *dhparam;
105 /* these are cached from first expand */
106 uschar *server_cipher_list;
107 /* only passed down to tls_error: */
108 host_item *host;
109} tls_ext_ctx_cb;
110
111/* should figure out a cleanup of API to handle state preserved per
112implementation, for various reasons, which can be void * in the APIs.
113For now, we hack around it. */
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114tls_ext_ctx_cb *client_static_cbinfo = NULL;
115tls_ext_ctx_cb *server_static_cbinfo = NULL;
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116
117static int
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118setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
119 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
059ec3d9 120
3f7eeb86 121/* Callbacks */
3bcbbbe2 122#ifdef EXIM_HAVE_OPENSSL_TLSEXT
3f7eeb86 123static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
3bcbbbe2 124#endif
3f7eeb86 125#ifdef EXPERIMENTAL_OCSP
f5d78688 126static int tls_server_stapling_cb(SSL *s, void *arg);
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127#endif
128
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129
130/*************************************************
131* Handle TLS error *
132*************************************************/
133
134/* Called from lots of places when errors occur before actually starting to do
135the TLS handshake, that is, while the session is still in clear. Always returns
136DEFER for a server and FAIL for a client so that most calls can use "return
137tls_error(...)" to do this processing and then give an appropriate return. A
138single function is used for both server and client, because it is called from
139some shared functions.
140
141Argument:
142 prefix text to include in the logged error
143 host NULL if setting up a server;
144 the connected host if setting up a client
7199e1ee 145 msg error message or NULL if we should ask OpenSSL
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146
147Returns: OK/DEFER/FAIL
148*/
149
150static int
7199e1ee 151tls_error(uschar *prefix, host_item *host, uschar *msg)
059ec3d9 152{
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153if (msg == NULL)
154 {
155 ERR_error_string(ERR_get_error(), ssl_errstring);
5ca6d115 156 msg = (uschar *)ssl_errstring;
7199e1ee
TF
157 }
158
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159if (host == NULL)
160 {
7199e1ee 161 uschar *conn_info = smtp_get_connection_info();
5ca6d115 162 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
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TF
163 conn_info += 5;
164 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
165 conn_info, prefix, msg);
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166 return DEFER;
167 }
168else
169 {
170 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
7199e1ee 171 host->name, host->address, prefix, msg);
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172 return FAIL;
173 }
174}
175
176
177
178/*************************************************
179* Callback to generate RSA key *
180*************************************************/
181
182/*
183Arguments:
184 s SSL connection
185 export not used
186 keylength keylength
187
188Returns: pointer to generated key
189*/
190
191static RSA *
192rsa_callback(SSL *s, int export, int keylength)
193{
194RSA *rsa_key;
195export = export; /* Shut picky compilers up */
196DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
197rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
198if (rsa_key == NULL)
199 {
200 ERR_error_string(ERR_get_error(), ssl_errstring);
201 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
202 ssl_errstring);
203 return NULL;
204 }
205return rsa_key;
206}
207
208
209
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210/* Extreme debug
211#if defined(EXPERIMENTAL_OCSP)
212void
213x509_store_dump_cert_s_names(X509_STORE * store)
214{
215STACK_OF(X509_OBJECT) * roots= store->objs;
216int i;
217static uschar name[256];
218
219for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
220 {
221 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
222 if(tmp_obj->type == X509_LU_X509)
223 {
224 X509 * current_cert= tmp_obj->data.x509;
225 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
226 debug_printf(" %s\n", name);
227 }
228 }
229}
230#endif
231*/
232
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233
234/*************************************************
235* Callback for verification *
236*************************************************/
237
238/* The SSL library does certificate verification if set up to do so. This
239callback has the current yes/no state is in "state". If verification succeeded,
240we set up the tls_peerdn string. If verification failed, what happens depends
241on whether the client is required to present a verifiable certificate or not.
242
243If verification is optional, we change the state to yes, but still log the
244verification error. For some reason (it really would help to have proper
245documentation of OpenSSL), this callback function then gets called again, this
246time with state = 1. In fact, that's useful, because we can set up the peerdn
247value, but we must take care not to set the private verified flag on the second
248time through.
249
250Note: this function is not called if the client fails to present a certificate
251when asked. We get here only if a certificate has been received. Handling of
252optional verification for this case is done when requesting SSL to verify, by
253setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
254
255Arguments:
256 state current yes/no state as 1/0
257 x509ctx certificate information.
a2ff477a 258 client TRUE for client startup, FALSE for server startup
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259
260Returns: 1 if verified, 0 if not
261*/
262
263static int
f5d78688 264verify_callback(int state, X509_STORE_CTX *x509ctx, tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
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265{
266static uschar txt[256];
267
268X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert),
269 CS txt, sizeof(txt));
270
271if (state == 0)
272 {
273 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
274 x509ctx->error_depth,
275 X509_verify_cert_error_string(x509ctx->error),
276 txt);
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277 tlsp->certificate_verified = FALSE;
278 *calledp = TRUE;
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279 if (!*optionalp)
280 {
281 tlsp->peercert = X509_dup(x509ctx->current_cert);
282 return 0; /* reject */
283 }
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284 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
285 "tls_try_verify_hosts)\n");
286 return 1; /* accept */
287 }
288
289if (x509ctx->error_depth != 0)
290 {
291 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n",
292 x509ctx->error_depth, txt);
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293#ifdef EXPERIMENTAL_OCSP
294 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
295 { /* client, wanting stapling */
296 /* Add the server cert's signing chain as the one
297 for the verification of the OCSP stapled information. */
298
299 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
300 x509ctx->current_cert))
301 ERR_clear_error();
302 }
303#endif
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304 }
305else
306 {
307 DEBUG(D_tls) debug_printf("SSL%s peer: %s\n",
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308 *calledp ? "" : " authenticated", txt);
309 tlsp->peerdn = txt;
9d1c15ef 310 tlsp->peercert = X509_dup(x509ctx->current_cert);
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311 }
312
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313/*XXX JGH: this looks bogus - we set "verified" first time through, which
314will be for the root CS cert (calls work down the chain). Why should it
315not be on the last call, where we're setting peerdn?
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316
317To test: set up a chain anchored by a good root-CA but with a bad server cert.
318Does certificate_verified get set?
f5d78688 319*/
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320if (!*calledp) tlsp->certificate_verified = TRUE;
321*calledp = TRUE;
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322
323return 1; /* accept */
324}
325
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326static int
327verify_callback_client(int state, X509_STORE_CTX *x509ctx)
328{
f5d78688 329return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
a2ff477a
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330}
331
332static int
333verify_callback_server(int state, X509_STORE_CTX *x509ctx)
334{
f5d78688 335return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
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336}
337
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338
339
340/*************************************************
341* Information callback *
342*************************************************/
343
344/* The SSL library functions call this from time to time to indicate what they
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345are doing. We copy the string to the debugging output when TLS debugging has
346been requested.
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347
348Arguments:
349 s the SSL connection
350 where
351 ret
352
353Returns: nothing
354*/
355
356static void
357info_callback(SSL *s, int where, int ret)
358{
359where = where;
360ret = ret;
361DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
362}
363
364
365
366/*************************************************
367* Initialize for DH *
368*************************************************/
369
370/* If dhparam is set, expand it, and load up the parameters for DH encryption.
371
372Arguments:
a799883d 373 dhparam DH parameter file or fixed parameter identity string
7199e1ee 374 host connected host, if client; NULL if server
059ec3d9
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375
376Returns: TRUE if OK (nothing to set up, or setup worked)
377*/
378
379static BOOL
a799883d 380init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
059ec3d9 381{
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382BIO *bio;
383DH *dh;
384uschar *dhexpanded;
a799883d 385const char *pem;
059ec3d9
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386
387if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
388 return FALSE;
389
a799883d 390if (dhexpanded == NULL || *dhexpanded == '\0')
059ec3d9 391 {
a799883d 392 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
059ec3d9 393 }
a799883d 394else if (dhexpanded[0] == '/')
059ec3d9 395 {
a799883d
PP
396 bio = BIO_new_file(CS dhexpanded, "r");
397 if (bio == NULL)
059ec3d9 398 {
7199e1ee 399 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
a799883d
PP
400 host, US strerror(errno));
401 return FALSE;
059ec3d9 402 }
a799883d
PP
403 }
404else
405 {
406 if (Ustrcmp(dhexpanded, "none") == 0)
059ec3d9 407 {
a799883d
PP
408 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
409 return TRUE;
059ec3d9 410 }
a799883d
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411
412 pem = std_dh_prime_named(dhexpanded);
413 if (!pem)
414 {
415 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
416 host, US strerror(errno));
417 return FALSE;
418 }
419 bio = BIO_new_mem_buf(CS pem, -1);
420 }
421
422dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
423if (dh == NULL)
424 {
059ec3d9 425 BIO_free(bio);
a799883d
PP
426 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
427 host, NULL);
428 return FALSE;
429 }
430
431/* Even if it is larger, we silently return success rather than cause things
432 * to fail out, so that a too-large DH will not knock out all TLS; it's a
433 * debatable choice. */
434if ((8*DH_size(dh)) > tls_dh_max_bits)
435 {
436 DEBUG(D_tls)
437 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
438 8*DH_size(dh), tls_dh_max_bits);
439 }
440else
441 {
442 SSL_CTX_set_tmp_dh(sctx, dh);
443 DEBUG(D_tls)
444 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
445 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
059ec3d9
PH
446 }
447
a799883d
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448DH_free(dh);
449BIO_free(bio);
450
451return TRUE;
059ec3d9
PH
452}
453
454
455
456
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457#ifdef EXPERIMENTAL_OCSP
458/*************************************************
459* Load OCSP information into state *
460*************************************************/
461
f5d78688 462/* Called to load the server OCSP response from the given file into memory, once
3f7eeb86
PP
463caller has determined this is needed. Checks validity. Debugs a message
464if invalid.
465
466ASSUMES: single response, for single cert.
467
468Arguments:
469 sctx the SSL_CTX* to update
470 cbinfo various parts of session state
471 expanded the filename putatively holding an OCSP response
472
473*/
474
475static void
f5d78688 476ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
3f7eeb86
PP
477{
478BIO *bio;
479OCSP_RESPONSE *resp;
480OCSP_BASICRESP *basic_response;
481OCSP_SINGLERESP *single_response;
482ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
483X509_STORE *store;
484unsigned long verify_flags;
485int status, reason, i;
486
f5d78688
JH
487cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
488if (cbinfo->u_ocsp.server.response)
3f7eeb86 489 {
f5d78688
JH
490 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
491 cbinfo->u_ocsp.server.response = NULL;
3f7eeb86
PP
492 }
493
f5d78688 494bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
3f7eeb86
PP
495if (!bio)
496 {
497 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
f5d78688 498 cbinfo->u_ocsp.server.file_expanded);
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PP
499 return;
500 }
501
502resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
503BIO_free(bio);
504if (!resp)
505 {
506 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
507 return;
508 }
509
510status = OCSP_response_status(resp);
511if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
512 {
513 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
514 OCSP_response_status_str(status), status);
f5d78688 515 goto bad;
3f7eeb86
PP
516 }
517
518basic_response = OCSP_response_get1_basic(resp);
519if (!basic_response)
520 {
521 DEBUG(D_tls)
522 debug_printf("OCSP response parse error: unable to extract basic response.\n");
f5d78688 523 goto bad;
3f7eeb86
PP
524 }
525
526store = SSL_CTX_get_cert_store(sctx);
527verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
528
529/* May need to expose ability to adjust those flags?
530OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
531OCSP_TRUSTOTHER OCSP_NOINTERN */
532
533i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
534if (i <= 0)
535 {
536 DEBUG(D_tls) {
537 ERR_error_string(ERR_get_error(), ssl_errstring);
538 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
f5d78688
JH
539 }
540 goto bad;
3f7eeb86
PP
541 }
542
543/* Here's the simplifying assumption: there's only one response, for the
544one certificate we use, and nothing for anything else in a chain. If this
545proves false, we need to extract a cert id from our issued cert
546(tls_certificate) and use that for OCSP_resp_find_status() (which finds the
547right cert in the stack and then calls OCSP_single_get0_status()).
548
549I'm hoping to avoid reworking a bunch more of how we handle state here. */
550single_response = OCSP_resp_get0(basic_response, 0);
551if (!single_response)
552 {
553 DEBUG(D_tls)
554 debug_printf("Unable to get first response from OCSP basic response.\n");
f5d78688 555 goto bad;
3f7eeb86
PP
556 }
557
558status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
f5d78688 559if (status != V_OCSP_CERTSTATUS_GOOD)
3f7eeb86 560 {
f5d78688
JH
561 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
562 OCSP_cert_status_str(status), status,
563 OCSP_crl_reason_str(reason), reason);
564 goto bad;
3f7eeb86
PP
565 }
566
567if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
568 {
569 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
f5d78688 570 goto bad;
3f7eeb86
PP
571 }
572
f5d78688
JH
573supply_response:
574cbinfo->u_ocsp.server.response = resp;
575return;
576
577bad:
578if (running_in_test_harness)
579 {
580 extern char ** environ;
581 uschar ** p;
582 for (p = USS environ; *p != NULL; p++)
583 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
584 {
585 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
586 goto supply_response;
587 }
588 }
589return;
3f7eeb86 590}
f5d78688 591#endif /*EXPERIMENTAL_OCSP*/
3f7eeb86
PP
592
593
594
595
059ec3d9 596/*************************************************
7be682ca
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597* Expand key and cert file specs *
598*************************************************/
599
f5d78688 600/* Called once during tls_init and possibly again during TLS setup, for a
7be682ca
PP
601new context, if Server Name Indication was used and tls_sni was seen in
602the certificate string.
603
604Arguments:
605 sctx the SSL_CTX* to update
606 cbinfo various parts of session state
607
608Returns: OK/DEFER/FAIL
609*/
610
611static int
3f7eeb86 612tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
7be682ca
PP
613{
614uschar *expanded;
615
616if (cbinfo->certificate == NULL)
617 return OK;
618
d9b2312b
JH
619if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
620 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
621 Ustrstr(cbinfo->certificate, US"tls_out_sni")
622 )
7be682ca
PP
623 reexpand_tls_files_for_sni = TRUE;
624
625if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
626 return DEFER;
627
628if (expanded != NULL)
629 {
630 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
631 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
632 return tls_error(string_sprintf(
633 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
634 cbinfo->host, NULL);
635 }
636
637if (cbinfo->privatekey != NULL &&
638 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
639 return DEFER;
640
641/* If expansion was forced to fail, key_expanded will be NULL. If the result
642of the expansion is an empty string, ignore it also, and assume the private
643key is in the same file as the certificate. */
644
645if (expanded != NULL && *expanded != 0)
646 {
647 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
648 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
649 return tls_error(string_sprintf(
650 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
651 }
652
3f7eeb86 653#ifdef EXPERIMENTAL_OCSP
f5d78688 654if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
3f7eeb86 655 {
f5d78688 656 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
3f7eeb86
PP
657 return DEFER;
658
659 if (expanded != NULL && *expanded != 0)
660 {
661 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
f5d78688
JH
662 if (cbinfo->u_ocsp.server.file_expanded &&
663 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
3f7eeb86
PP
664 {
665 DEBUG(D_tls)
666 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
667 } else {
668 ocsp_load_response(sctx, cbinfo, expanded);
669 }
670 }
671 }
672#endif
673
7be682ca
PP
674return OK;
675}
676
677
678
679
680/*************************************************
681* Callback to handle SNI *
682*************************************************/
683
684/* Called when acting as server during the TLS session setup if a Server Name
685Indication extension was sent by the client.
686
687API documentation is OpenSSL s_server.c implementation.
688
689Arguments:
690 s SSL* of the current session
691 ad unknown (part of OpenSSL API) (unused)
692 arg Callback of "our" registered data
693
694Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
695*/
696
3bcbbbe2 697#ifdef EXIM_HAVE_OPENSSL_TLSEXT
7be682ca 698static int
7be682ca
PP
699tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
700{
701const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
3f7eeb86 702tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
7be682ca 703int rc;
3f0945ff 704int old_pool = store_pool;
7be682ca
PP
705
706if (!servername)
707 return SSL_TLSEXT_ERR_OK;
708
3f0945ff 709DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
7be682ca
PP
710 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
711
712/* Make the extension value available for expansion */
3f0945ff 713store_pool = POOL_PERM;
817d9f57 714tls_in.sni = string_copy(US servername);
3f0945ff 715store_pool = old_pool;
7be682ca
PP
716
717if (!reexpand_tls_files_for_sni)
718 return SSL_TLSEXT_ERR_OK;
719
720/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
721not confident that memcpy wouldn't break some internal reference counting.
722Especially since there's a references struct member, which would be off. */
723
817d9f57
JH
724server_sni = SSL_CTX_new(SSLv23_server_method());
725if (!server_sni)
7be682ca
PP
726 {
727 ERR_error_string(ERR_get_error(), ssl_errstring);
728 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
729 return SSL_TLSEXT_ERR_NOACK;
730 }
731
732/* Not sure how many of these are actually needed, since SSL object
733already exists. Might even need this selfsame callback, for reneg? */
734
817d9f57
JH
735SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
736SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
737SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
738SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
739SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
740SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
7be682ca 741if (cbinfo->server_cipher_list)
817d9f57 742 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
3f7eeb86 743#ifdef EXPERIMENTAL_OCSP
f5d78688 744if (cbinfo->u_ocsp.server.file)
3f7eeb86 745 {
f5d78688 746 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
14c7b357 747 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
3f7eeb86
PP
748 }
749#endif
7be682ca 750
983207c1 751rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
7be682ca
PP
752if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
753
3f7eeb86
PP
754/* do this after setup_certs, because this can require the certs for verifying
755OCSP information. */
817d9f57 756rc = tls_expand_session_files(server_sni, cbinfo);
7be682ca
PP
757if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
758
389ca47a 759rc = init_dh(server_sni, cbinfo->dhparam, NULL);
a799883d
PP
760if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
761
7be682ca 762DEBUG(D_tls) debug_printf("Switching SSL context.\n");
817d9f57 763SSL_set_SSL_CTX(s, server_sni);
7be682ca
PP
764
765return SSL_TLSEXT_ERR_OK;
766}
3bcbbbe2 767#endif /* EXIM_HAVE_OPENSSL_TLSEXT */
7be682ca
PP
768
769
770
771
3f7eeb86 772#ifdef EXPERIMENTAL_OCSP
f5d78688 773
3f7eeb86
PP
774/*************************************************
775* Callback to handle OCSP Stapling *
776*************************************************/
777
778/* Called when acting as server during the TLS session setup if the client
779requests OCSP information with a Certificate Status Request.
780
781Documentation via openssl s_server.c and the Apache patch from the OpenSSL
782project.
783
784*/
785
786static int
f5d78688 787tls_server_stapling_cb(SSL *s, void *arg)
3f7eeb86
PP
788{
789const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
790uschar *response_der;
791int response_der_len;
792
f5d78688
JH
793if (log_extra_selector & LX_tls_cipher)
794 log_write(0, LOG_MAIN, "[%s] Recieved OCSP stapling req;%s responding",
795 sender_host_address, cbinfo->u_ocsp.server.response ? "":" not");
796else
797 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.",
798 cbinfo->u_ocsp.server.response ? "have" : "lack");
799
800if (!cbinfo->u_ocsp.server.response)
3f7eeb86
PP
801 return SSL_TLSEXT_ERR_NOACK;
802
803response_der = NULL;
f5d78688 804response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, &response_der);
3f7eeb86
PP
805if (response_der_len <= 0)
806 return SSL_TLSEXT_ERR_NOACK;
807
5e55c7a9 808SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
3f7eeb86
PP
809return SSL_TLSEXT_ERR_OK;
810}
811
3f7eeb86 812
f5d78688
JH
813static void
814time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
815{
816BIO_printf(bp, "\t%s: ", str);
817ASN1_GENERALIZEDTIME_print(bp, time);
818BIO_puts(bp, "\n");
819}
820
821static int
822tls_client_stapling_cb(SSL *s, void *arg)
823{
824tls_ext_ctx_cb * cbinfo = arg;
825const unsigned char * p;
826int len;
827OCSP_RESPONSE * rsp;
828OCSP_BASICRESP * bs;
829int i;
830
831DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
832len = SSL_get_tlsext_status_ocsp_resp(s, &p);
833if(!p)
834 {
835 if (log_extra_selector & LX_tls_cipher)
836 log_write(0, LOG_MAIN, "Received TLS status response, null content");
837 else
838 DEBUG(D_tls) debug_printf(" null\n");
839 return 0; /* This is the fail case for require-ocsp; none from server */
840 }
841if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
842 {
843 if (log_extra_selector & LX_tls_cipher)
844 log_write(0, LOG_MAIN, "Received TLS status response, parse error");
845 else
846 DEBUG(D_tls) debug_printf(" parse error\n");
847 return 0;
848 }
849
850if(!(bs = OCSP_response_get1_basic(rsp)))
851 {
852 if (log_extra_selector & LX_tls_cipher)
853 log_write(0, LOG_MAIN, "Received TLS status response, error parsing response");
854 else
855 DEBUG(D_tls) debug_printf(" error parsing response\n");
856 OCSP_RESPONSE_free(rsp);
857 return 0;
858 }
859
860/* We'd check the nonce here if we'd put one in the request. */
861/* However that would defeat cacheability on the server so we don't. */
862
863
864/* This section of code reworked from OpenSSL apps source;
865 The OpenSSL Project retains copyright:
866 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
867*/
868 {
869 BIO * bp = NULL;
870 OCSP_CERTID *id;
871 int status, reason;
872 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
873
874 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
875
876 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
877
878 /* Use the chain that verified the server cert to verify the stapled info */
879 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
880
881 if ((i = OCSP_basic_verify(bs, NULL, cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
882 {
883 BIO_printf(bp, "OCSP response verify failure\n");
884 ERR_print_errors(bp);
885 i = 0;
886 goto out;
887 }
888
889 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
890
891 {
892 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
893 OCSP_SINGLERESP * single;
894
895 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
896 {
897 log_write(0, LOG_MAIN, "OCSP stapling with multiple responses not handled");
898 goto out;
899 }
900 single = OCSP_resp_get0(bs, 0);
901 status = OCSP_single_get0_status(single, &reason, &rev, &thisupd, &nextupd);
902 }
903
904 i = 0;
905 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
906 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
907 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
908 {
909 DEBUG(D_tls) ERR_print_errors(bp);
910 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
911 goto out;
912 }
913
914 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", OCSP_cert_status_str(status));
915 switch(status)
916 {
917 case V_OCSP_CERTSTATUS_GOOD:
918 i = 1;
919 break;
920 case V_OCSP_CERTSTATUS_REVOKED:
921 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
922 reason != -1 ? "; reason: " : "", reason != -1 ? OCSP_crl_reason_str(reason) : "");
923 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
924 i = 0;
925 break;
926 default:
927 log_write(0, LOG_MAIN, "Server certificate status unknown, in OCSP stapling");
928 i = 0;
929 break;
930 }
931 out:
932 BIO_free(bp);
933 }
934
935OCSP_RESPONSE_free(rsp);
936return i;
937}
938#endif /*EXPERIMENTAL_OCSP*/
3f7eeb86
PP
939
940
941
7be682ca 942/*************************************************
059ec3d9
PH
943* Initialize for TLS *
944*************************************************/
945
946/* Called from both server and client code, to do preliminary initialization of
947the library.
948
949Arguments:
950 host connected host, if client; NULL if server
951 dhparam DH parameter file
952 certificate certificate file
953 privatekey private key
f5d78688 954 ocsp_file file of stapling info (server); flag for require ocsp (client)
059ec3d9
PH
955 addr address if client; NULL if server (for some randomness)
956
957Returns: OK/DEFER/FAIL
958*/
959
960static int
817d9f57 961tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
3f7eeb86
PP
962 uschar *privatekey,
963#ifdef EXPERIMENTAL_OCSP
964 uschar *ocsp_file,
965#endif
817d9f57 966 address_item *addr, tls_ext_ctx_cb ** cbp)
059ec3d9 967{
77bb000f 968long init_options;
7be682ca 969int rc;
77bb000f 970BOOL okay;
7be682ca
PP
971tls_ext_ctx_cb *cbinfo;
972
973cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
974cbinfo->certificate = certificate;
975cbinfo->privatekey = privatekey;
3f7eeb86 976#ifdef EXPERIMENTAL_OCSP
f5d78688
JH
977if ((cbinfo->is_server = host==NULL))
978 {
979 cbinfo->u_ocsp.server.file = ocsp_file;
980 cbinfo->u_ocsp.server.file_expanded = NULL;
981 cbinfo->u_ocsp.server.response = NULL;
982 }
983else
984 cbinfo->u_ocsp.client.verify_store = NULL;
3f7eeb86 985#endif
7be682ca
PP
986cbinfo->dhparam = dhparam;
987cbinfo->host = host;
77bb000f 988
059ec3d9
PH
989SSL_load_error_strings(); /* basic set up */
990OpenSSL_add_ssl_algorithms();
991
388d6564 992#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
77bb000f 993/* SHA256 is becoming ever more popular. This makes sure it gets added to the
a0475b69
TK
994list of available digests. */
995EVP_add_digest(EVP_sha256());
cf1ef1a9 996#endif
a0475b69 997
f0f5a555
PP
998/* Create a context.
999The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1000negotiation in the different methods; as far as I can tell, the only
1001*_{server,client}_method which allows negotiation is SSLv23, which exists even
1002when OpenSSL is built without SSLv2 support.
1003By disabling with openssl_options, we can let admins re-enable with the
1004existing knob. */
059ec3d9 1005
817d9f57 1006*ctxp = SSL_CTX_new((host == NULL)?
059ec3d9
PH
1007 SSLv23_server_method() : SSLv23_client_method());
1008
817d9f57 1009if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
059ec3d9
PH
1010
1011/* It turns out that we need to seed the random number generator this early in
1012order to get the full complement of ciphers to work. It took me roughly a day
1013of work to discover this by experiment.
1014
1015On systems that have /dev/urandom, SSL may automatically seed itself from
1016there. Otherwise, we have to make something up as best we can. Double check
1017afterwards. */
1018
1019if (!RAND_status())
1020 {
1021 randstuff r;
9e3331ea 1022 gettimeofday(&r.tv, NULL);
059ec3d9
PH
1023 r.p = getpid();
1024
1025 RAND_seed((uschar *)(&r), sizeof(r));
1026 RAND_seed((uschar *)big_buffer, big_buffer_size);
1027 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1028
1029 if (!RAND_status())
7199e1ee 1030 return tls_error(US"RAND_status", host,
5ca6d115 1031 US"unable to seed random number generator");
059ec3d9
PH
1032 }
1033
1034/* Set up the information callback, which outputs if debugging is at a suitable
1035level. */
1036
817d9f57 1037SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
059ec3d9 1038
c80c5570 1039/* Automatically re-try reads/writes after renegotiation. */
817d9f57 1040(void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
c80c5570 1041
77bb000f
PP
1042/* Apply administrator-supplied work-arounds.
1043Historically we applied just one requested option,
1044SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1045moved to an administrator-controlled list of options to specify and
1046grandfathered in the first one as the default value for "openssl_options".
059ec3d9 1047
77bb000f
PP
1048No OpenSSL version number checks: the options we accept depend upon the
1049availability of the option value macros from OpenSSL. */
059ec3d9 1050
77bb000f
PP
1051okay = tls_openssl_options_parse(openssl_options, &init_options);
1052if (!okay)
73a46702 1053 return tls_error(US"openssl_options parsing failed", host, NULL);
77bb000f
PP
1054
1055if (init_options)
1056 {
1057 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
817d9f57 1058 if (!(SSL_CTX_set_options(*ctxp, init_options)))
77bb000f
PP
1059 return tls_error(string_sprintf(
1060 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1061 }
1062else
1063 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
059ec3d9
PH
1064
1065/* Initialize with DH parameters if supplied */
1066
817d9f57 1067if (!init_dh(*ctxp, dhparam, host)) return DEFER;
059ec3d9 1068
3f7eeb86 1069/* Set up certificate and key (and perhaps OCSP info) */
059ec3d9 1070
817d9f57 1071rc = tls_expand_session_files(*ctxp, cbinfo);
7be682ca 1072if (rc != OK) return rc;
c91535f3 1073
7be682ca 1074/* If we need to handle SNI, do so */
3bcbbbe2 1075#ifdef EXIM_HAVE_OPENSSL_TLSEXT
f5d78688 1076if (host == NULL) /* server */
3f0945ff 1077 {
f5d78688
JH
1078# ifdef EXPERIMENTAL_OCSP
1079 /* We check u_ocsp.server.file, not server.response, because we care about if
3f7eeb86
PP
1080 the option exists, not what the current expansion might be, as SNI might
1081 change the certificate and OCSP file in use between now and the time the
1082 callback is invoked. */
f5d78688 1083 if (cbinfo->u_ocsp.server.file)
3f7eeb86 1084 {
f5d78688 1085 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
5e55c7a9 1086 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
3f7eeb86 1087 }
f5d78688 1088# endif
3f0945ff
PP
1089 /* We always do this, so that $tls_sni is available even if not used in
1090 tls_certificate */
817d9f57
JH
1091 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1092 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
3f0945ff 1093 }
f5d78688
JH
1094# ifdef EXPERIMENTAL_OCSP
1095else /* client */
1096 if(ocsp_file) /* wanting stapling */
1097 {
1098 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1099 {
1100 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1101 return FAIL;
1102 }
1103 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1104 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1105 }
1106# endif
7be682ca 1107#endif
059ec3d9
PH
1108
1109/* Set up the RSA callback */
1110
817d9f57 1111SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
059ec3d9
PH
1112
1113/* Finally, set the timeout, and we are done */
1114
817d9f57 1115SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
059ec3d9 1116DEBUG(D_tls) debug_printf("Initialized TLS\n");
7be682ca 1117
817d9f57 1118*cbp = cbinfo;
7be682ca 1119
059ec3d9
PH
1120return OK;
1121}
1122
1123
1124
1125
1126/*************************************************
1127* Get name of cipher in use *
1128*************************************************/
1129
817d9f57 1130/*
059ec3d9 1131Argument: pointer to an SSL structure for the connection
817d9f57
JH
1132 buffer to use for answer
1133 size of buffer
1134 pointer to number of bits for cipher
059ec3d9
PH
1135Returns: nothing
1136*/
1137
1138static void
817d9f57 1139construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
059ec3d9 1140{
57b3a7f5
PP
1141/* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1142yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1143the accessor functions use const in the prototype. */
1144const SSL_CIPHER *c;
d9784128 1145const uschar *ver;
059ec3d9 1146
d9784128 1147ver = (const uschar *)SSL_get_version(ssl);
059ec3d9 1148
57b3a7f5 1149c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1150SSL_CIPHER_get_bits(c, bits);
059ec3d9 1151
817d9f57
JH
1152string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1153 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1154
1155DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1156}
1157
1158
1159
1160
1161
1162/*************************************************
1163* Set up for verifying certificates *
1164*************************************************/
1165
1166/* Called by both client and server startup
1167
1168Arguments:
7be682ca 1169 sctx SSL_CTX* to initialise
059ec3d9
PH
1170 certs certs file or NULL
1171 crl CRL file or NULL
1172 host NULL in a server; the remote host in a client
1173 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1174 otherwise passed as FALSE
983207c1 1175 cert_vfy_cb Callback function for certificate verification
059ec3d9
PH
1176
1177Returns: OK/DEFER/FAIL
1178*/
1179
1180static int
983207c1
JH
1181setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1182 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
059ec3d9
PH
1183{
1184uschar *expcerts, *expcrl;
1185
1186if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1187 return DEFER;
1188
26e72755 1189if (expcerts != NULL && *expcerts != '\0')
059ec3d9
PH
1190 {
1191 struct stat statbuf;
7be682ca 1192 if (!SSL_CTX_set_default_verify_paths(sctx))
7199e1ee 1193 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
059ec3d9
PH
1194
1195 if (Ustat(expcerts, &statbuf) < 0)
1196 {
1197 log_write(0, LOG_MAIN|LOG_PANIC,
1198 "failed to stat %s for certificates", expcerts);
1199 return DEFER;
1200 }
1201 else
1202 {
1203 uschar *file, *dir;
1204 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1205 { file = NULL; dir = expcerts; }
1206 else
1207 { file = expcerts; dir = NULL; }
1208
1209 /* If a certificate file is empty, the next function fails with an
1210 unhelpful error message. If we skip it, we get the correct behaviour (no
1211 certificates are recognized, but the error message is still misleading (it
1212 says no certificate was supplied.) But this is better. */
1213
1214 if ((file == NULL || statbuf.st_size > 0) &&
7be682ca 1215 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
7199e1ee 1216 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
059ec3d9
PH
1217
1218 if (file != NULL)
1219 {
7be682ca 1220 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
059ec3d9
PH
1221 }
1222 }
1223
1224 /* Handle a certificate revocation list. */
1225
1226 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1227
8b417f2c
PH
1228 /* This bit of code is now the version supplied by Lars Mainka. (I have
1229 * merely reformatted it into the Exim code style.)
1230
1231 * "From here I changed the code to add support for multiple crl's
1232 * in pem format in one file or to support hashed directory entries in
1233 * pem format instead of a file. This method now uses the library function
1234 * X509_STORE_load_locations to add the CRL location to the SSL context.
1235 * OpenSSL will then handle the verify against CA certs and CRLs by
1236 * itself in the verify callback." */
1237
059ec3d9
PH
1238 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1239 if (expcrl != NULL && *expcrl != 0)
1240 {
8b417f2c
PH
1241 struct stat statbufcrl;
1242 if (Ustat(expcrl, &statbufcrl) < 0)
1243 {
1244 log_write(0, LOG_MAIN|LOG_PANIC,
1245 "failed to stat %s for certificates revocation lists", expcrl);
1246 return DEFER;
1247 }
1248 else
059ec3d9 1249 {
8b417f2c
PH
1250 /* is it a file or directory? */
1251 uschar *file, *dir;
7be682ca 1252 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1253 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1254 {
8b417f2c
PH
1255 file = NULL;
1256 dir = expcrl;
1257 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1258 }
1259 else
1260 {
8b417f2c
PH
1261 file = expcrl;
1262 dir = NULL;
1263 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1264 }
8b417f2c 1265 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
7199e1ee 1266 return tls_error(US"X509_STORE_load_locations", host, NULL);
8b417f2c
PH
1267
1268 /* setting the flags to check against the complete crl chain */
1269
1270 X509_STORE_set_flags(cvstore,
1271 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1272 }
059ec3d9
PH
1273 }
1274
1275 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1276
1277 /* If verification is optional, don't fail if no certificate */
1278
7be682ca 1279 SSL_CTX_set_verify(sctx,
059ec3d9 1280 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1281 cert_vfy_cb);
059ec3d9
PH
1282 }
1283
1284return OK;
1285}
1286
1287
1288
1289/*************************************************
1290* Start a TLS session in a server *
1291*************************************************/
1292
1293/* This is called when Exim is running as a server, after having received
1294the STARTTLS command. It must respond to that command, and then negotiate
1295a TLS session.
1296
1297Arguments:
1298 require_ciphers allowed ciphers
1299
1300Returns: OK on success
1301 DEFER for errors before the start of the negotiation
1302 FAIL for errors during the negotation; the server can't
1303 continue running.
1304*/
1305
1306int
17c76198 1307tls_server_start(const uschar *require_ciphers)
059ec3d9
PH
1308{
1309int rc;
1310uschar *expciphers;
7be682ca 1311tls_ext_ctx_cb *cbinfo;
817d9f57 1312static uschar cipherbuf[256];
059ec3d9
PH
1313
1314/* Check for previous activation */
1315
817d9f57 1316if (tls_in.active >= 0)
059ec3d9 1317 {
5ca6d115 1318 tls_error(US"STARTTLS received after TLS started", NULL, US"");
059ec3d9
PH
1319 smtp_printf("554 Already in TLS\r\n");
1320 return FAIL;
1321 }
1322
1323/* Initialize the SSL library. If it fails, it will already have logged
1324the error. */
1325
817d9f57 1326rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
3f7eeb86
PP
1327#ifdef EXPERIMENTAL_OCSP
1328 tls_ocsp_file,
1329#endif
817d9f57 1330 NULL, &server_static_cbinfo);
059ec3d9 1331if (rc != OK) return rc;
817d9f57 1332cbinfo = server_static_cbinfo;
059ec3d9
PH
1333
1334if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1335 return FAIL;
1336
1337/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1338were historically separated by underscores. So that I can use either form in my
1339tests, and also for general convenience, we turn underscores into hyphens here.
1340*/
059ec3d9
PH
1341
1342if (expciphers != NULL)
1343 {
1344 uschar *s = expciphers;
1345 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1346 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1347 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
7199e1ee 1348 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
7be682ca 1349 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1350 }
1351
1352/* If this is a host for which certificate verification is mandatory or
1353optional, set up appropriately. */
1354
817d9f57 1355tls_in.certificate_verified = FALSE;
a2ff477a 1356server_verify_callback_called = FALSE;
059ec3d9
PH
1357
1358if (verify_check_host(&tls_verify_hosts) == OK)
1359 {
983207c1
JH
1360 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1361 FALSE, verify_callback_server);
059ec3d9 1362 if (rc != OK) return rc;
a2ff477a 1363 server_verify_optional = FALSE;
059ec3d9
PH
1364 }
1365else if (verify_check_host(&tls_try_verify_hosts) == OK)
1366 {
983207c1
JH
1367 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1368 TRUE, verify_callback_server);
059ec3d9 1369 if (rc != OK) return rc;
a2ff477a 1370 server_verify_optional = TRUE;
059ec3d9
PH
1371 }
1372
1373/* Prepare for new connection */
1374
817d9f57 1375if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
da3ad30d
PP
1376
1377/* Warning: we used to SSL_clear(ssl) here, it was removed.
1378 *
1379 * With the SSL_clear(), we get strange interoperability bugs with
1380 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1381 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1382 *
1383 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1384 * session shutdown. In this case, we have a brand new object and there's no
1385 * obvious reason to immediately clear it. I'm guessing that this was
1386 * originally added because of incomplete initialisation which the clear fixed,
1387 * in some historic release.
1388 */
059ec3d9
PH
1389
1390/* Set context and tell client to go ahead, except in the case of TLS startup
1391on connection, where outputting anything now upsets the clients and tends to
1392make them disconnect. We need to have an explicit fflush() here, to force out
1393the response. Other smtp_printf() calls do not need it, because in non-TLS
1394mode, the fflush() happens when smtp_getc() is called. */
1395
817d9f57
JH
1396SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1397if (!tls_in.on_connect)
059ec3d9
PH
1398 {
1399 smtp_printf("220 TLS go ahead\r\n");
1400 fflush(smtp_out);
1401 }
1402
1403/* Now negotiate the TLS session. We put our own timer on it, since it seems
1404that the OpenSSL library doesn't. */
1405
817d9f57
JH
1406SSL_set_wfd(server_ssl, fileno(smtp_out));
1407SSL_set_rfd(server_ssl, fileno(smtp_in));
1408SSL_set_accept_state(server_ssl);
059ec3d9
PH
1409
1410DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1411
1412sigalrm_seen = FALSE;
1413if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 1414rc = SSL_accept(server_ssl);
059ec3d9
PH
1415alarm(0);
1416
1417if (rc <= 0)
1418 {
7199e1ee 1419 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
77bb000f
PP
1420 if (ERR_get_error() == 0)
1421 log_write(0, LOG_MAIN,
a053d125 1422 "TLS client disconnected cleanly (rejected our certificate?)");
059ec3d9
PH
1423 return FAIL;
1424 }
1425
1426DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1427
1428/* TLS has been set up. Adjust the input functions to read via TLS,
1429and initialize things. */
1430
817d9f57
JH
1431construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1432tls_in.cipher = cipherbuf;
059ec3d9
PH
1433
1434DEBUG(D_tls)
1435 {
1436 uschar buf[2048];
817d9f57 1437 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
1438 debug_printf("Shared ciphers: %s\n", buf);
1439 }
1440
9d1c15ef
JH
1441/* Record the certificate we presented */
1442 {
1443 X509 * crt = SSL_get_certificate(server_ssl);
1444 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1445 }
059ec3d9 1446
817d9f57
JH
1447/* Only used by the server-side tls (tls_in), including tls_getc.
1448 Client-side (tls_out) reads (seem to?) go via
1449 smtp_read_response()/ip_recv().
1450 Hence no need to duplicate for _in and _out.
1451 */
059ec3d9
PH
1452ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1453ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1454ssl_xfer_eof = ssl_xfer_error = 0;
1455
1456receive_getc = tls_getc;
1457receive_ungetc = tls_ungetc;
1458receive_feof = tls_feof;
1459receive_ferror = tls_ferror;
58eb016e 1460receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 1461
817d9f57 1462tls_in.active = fileno(smtp_out);
059ec3d9
PH
1463return OK;
1464}
1465
1466
1467
1468
1469
1470/*************************************************
1471* Start a TLS session in a client *
1472*************************************************/
1473
1474/* Called from the smtp transport after STARTTLS has been accepted.
1475
1476Argument:
1477 fd the fd of the connection
1478 host connected host (for messages)
83da1223 1479 addr the first address
059ec3d9
PH
1480 certificate certificate file
1481 privatekey private key file
3f0945ff 1482 sni TLS SNI to send to remote host
059ec3d9
PH
1483 verify_certs file for certificate verify
1484 crl file containing CRL
1485 require_ciphers list of allowed ciphers
54c90be1
PP
1486 dh_min_bits minimum number of bits acceptable in server's DH prime
1487 (unused in OpenSSL)
83da1223 1488 timeout startup timeout
a63be306
WB
1489 verify_hosts mandatory client verification
1490 try_verify_hosts optional client verification
059ec3d9
PH
1491
1492Returns: OK on success
1493 FAIL otherwise - note that tls_error() will not give DEFER
1494 because this is not a server
1495*/
1496
1497int
f5d78688 1498tls_client_start(int fd, host_item *host, address_item *addr,
3f0945ff
PP
1499 uschar *certificate, uschar *privatekey, uschar *sni,
1500 uschar *verify_certs, uschar *crl,
f5d78688
JH
1501 uschar *require_ciphers,
1502#ifdef EXPERIMENTAL_OCSP
1503 uschar *hosts_require_ocsp,
1504#endif
a63be306
WB
1505 int dh_min_bits ARG_UNUSED, int timeout,
1506 uschar *verify_hosts, uschar *try_verify_hosts)
059ec3d9
PH
1507{
1508static uschar txt[256];
1509uschar *expciphers;
1510X509* server_cert;
1511int rc;
817d9f57 1512static uschar cipherbuf[256];
f5d78688
JH
1513#ifdef EXPERIMENTAL_OCSP
1514BOOL require_ocsp = verify_check_this_host(&hosts_require_ocsp,
1515 NULL, host->name, host->address, NULL) == OK;
1516#endif
059ec3d9 1517
f5d78688 1518rc = tls_init(&client_ctx, host, NULL, certificate, privatekey,
3f7eeb86 1519#ifdef EXPERIMENTAL_OCSP
f5d78688 1520 require_ocsp ? US"" : NULL,
3f7eeb86 1521#endif
817d9f57 1522 addr, &client_static_cbinfo);
059ec3d9
PH
1523if (rc != OK) return rc;
1524
817d9f57 1525tls_out.certificate_verified = FALSE;
a2ff477a 1526client_verify_callback_called = FALSE;
059ec3d9
PH
1527
1528if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1529 return FAIL;
1530
1531/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1532are separated by underscores. So that I can use either form in my tests, and
1533also for general convenience, we turn underscores into hyphens here. */
1534
1535if (expciphers != NULL)
1536 {
1537 uschar *s = expciphers;
1538 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1539 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1540 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
7199e1ee 1541 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
059ec3d9
PH
1542 }
1543
a63be306
WB
1544/* stick to the old behaviour for compatibility if tls_verify_certificates is
1545 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1546 the specified host patterns if one of them is defined */
1547if (((verify_hosts == NULL) && (try_verify_hosts == NULL)) ||
1548 (verify_check_host(&verify_hosts) == OK))
1549 {
1550 rc = setup_certs(client_ctx, verify_certs, crl, host, FALSE, verify_callback_client);
1551 if (rc != OK) return rc;
1552 client_verify_optional = FALSE;
1553 }
1554else if (verify_check_host(&try_verify_hosts) == OK)
1555 {
1556 rc = setup_certs(client_ctx, verify_certs, crl, host, TRUE, verify_callback_client);
1557 if (rc != OK) return rc;
1558 client_verify_optional = TRUE;
1559 }
059ec3d9 1560
817d9f57
JH
1561if ((client_ssl = SSL_new(client_ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1562SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1563SSL_set_fd(client_ssl, fd);
1564SSL_set_connect_state(client_ssl);
059ec3d9 1565
3f0945ff
PP
1566if (sni)
1567 {
817d9f57 1568 if (!expand_check(sni, US"tls_sni", &tls_out.sni))
3f0945ff 1569 return FAIL;
ec4b68e5 1570 if (tls_out.sni == NULL)
2c9a0e86
PP
1571 {
1572 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1573 }
ec4b68e5 1574 else if (!Ustrlen(tls_out.sni))
817d9f57 1575 tls_out.sni = NULL;
3f0945ff
PP
1576 else
1577 {
35731706 1578#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
1579 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1580 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706
PP
1581#else
1582 DEBUG(D_tls)
1583 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
02d9264f 1584 tls_out.sni);
35731706 1585#endif
3f0945ff
PP
1586 }
1587 }
1588
f5d78688
JH
1589#ifdef EXPERIMENTAL_OCSP
1590/* Request certificate status at connection-time. If the server
1591does OCSP stapling we will get the callback (set in tls_init()) */
1592if (require_ocsp)
1593 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1594#endif
1595
059ec3d9
PH
1596/* There doesn't seem to be a built-in timeout on connection. */
1597
1598DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1599sigalrm_seen = FALSE;
1600alarm(timeout);
817d9f57 1601rc = SSL_connect(client_ssl);
059ec3d9
PH
1602alarm(0);
1603
1604if (rc <= 0)
7199e1ee 1605 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
059ec3d9
PH
1606
1607DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1608
453a6645 1609/* Beware anonymous ciphers which lead to server_cert being NULL */
9d1c15ef 1610/*XXX server_cert is never freed... use X509_free() */
817d9f57 1611server_cert = SSL_get_peer_certificate (client_ssl);
453a6645
PP
1612if (server_cert)
1613 {
817d9f57 1614 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
453a6645 1615 CS txt, sizeof(txt));
9d1c15ef 1616 tls_out.peerdn = txt; /*XXX a static buffer... */
453a6645
PP
1617 }
1618else
817d9f57 1619 tls_out.peerdn = NULL;
059ec3d9 1620
817d9f57
JH
1621construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1622tls_out.cipher = cipherbuf;
059ec3d9 1623
9d1c15ef
JH
1624/* Record the certificate we presented */
1625 {
1626 X509 * crt = SSL_get_certificate(client_ssl);
1627 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1628 }
1629
817d9f57 1630tls_out.active = fd;
059ec3d9
PH
1631return OK;
1632}
1633
1634
1635
1636
1637
1638/*************************************************
1639* TLS version of getc *
1640*************************************************/
1641
1642/* This gets the next byte from the TLS input buffer. If the buffer is empty,
1643it refills the buffer via the SSL reading function.
1644
1645Arguments: none
1646Returns: the next character or EOF
817d9f57
JH
1647
1648Only used by the server-side TLS.
059ec3d9
PH
1649*/
1650
1651int
1652tls_getc(void)
1653{
1654if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1655 {
1656 int error;
1657 int inbytes;
1658
817d9f57 1659 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
c80c5570 1660 ssl_xfer_buffer, ssl_xfer_buffer_size);
059ec3d9
PH
1661
1662 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57
JH
1663 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1664 error = SSL_get_error(server_ssl, inbytes);
059ec3d9
PH
1665 alarm(0);
1666
1667 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1668 closed down, not that the socket itself has been closed down. Revert to
1669 non-SSL handling. */
1670
1671 if (error == SSL_ERROR_ZERO_RETURN)
1672 {
1673 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1674
1675 receive_getc = smtp_getc;
1676 receive_ungetc = smtp_ungetc;
1677 receive_feof = smtp_feof;
1678 receive_ferror = smtp_ferror;
58eb016e 1679 receive_smtp_buffered = smtp_buffered;
059ec3d9 1680
817d9f57
JH
1681 SSL_free(server_ssl);
1682 server_ssl = NULL;
1683 tls_in.active = -1;
1684 tls_in.bits = 0;
1685 tls_in.cipher = NULL;
1686 tls_in.peerdn = NULL;
1687 tls_in.sni = NULL;
059ec3d9
PH
1688
1689 return smtp_getc();
1690 }
1691
1692 /* Handle genuine errors */
1693
ba084640
PP
1694 else if (error == SSL_ERROR_SSL)
1695 {
1696 ERR_error_string(ERR_get_error(), ssl_errstring);
89dd51cd 1697 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
ba084640
PP
1698 ssl_xfer_error = 1;
1699 return EOF;
1700 }
1701
059ec3d9
PH
1702 else if (error != SSL_ERROR_NONE)
1703 {
1704 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1705 ssl_xfer_error = 1;
1706 return EOF;
1707 }
c80c5570 1708
80a47a2c
TK
1709#ifndef DISABLE_DKIM
1710 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1711#endif
059ec3d9
PH
1712 ssl_xfer_buffer_hwm = inbytes;
1713 ssl_xfer_buffer_lwm = 0;
1714 }
1715
1716/* Something in the buffer; return next uschar */
1717
1718return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1719}
1720
1721
1722
1723/*************************************************
1724* Read bytes from TLS channel *
1725*************************************************/
1726
1727/*
1728Arguments:
1729 buff buffer of data
1730 len size of buffer
1731
1732Returns: the number of bytes read
1733 -1 after a failed read
817d9f57
JH
1734
1735Only used by the client-side TLS.
059ec3d9
PH
1736*/
1737
1738int
389ca47a 1739tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 1740{
389ca47a 1741SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
1742int inbytes;
1743int error;
1744
389ca47a 1745DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 1746 buff, (unsigned int)len);
059ec3d9 1747
389ca47a
JH
1748inbytes = SSL_read(ssl, CS buff, len);
1749error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
1750
1751if (error == SSL_ERROR_ZERO_RETURN)
1752 {
1753 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1754 return -1;
1755 }
1756else if (error != SSL_ERROR_NONE)
1757 {
1758 return -1;
1759 }
1760
1761return inbytes;
1762}
1763
1764
1765
1766
1767
1768/*************************************************
1769* Write bytes down TLS channel *
1770*************************************************/
1771
1772/*
1773Arguments:
817d9f57 1774 is_server channel specifier
059ec3d9
PH
1775 buff buffer of data
1776 len number of bytes
1777
1778Returns: the number of bytes after a successful write,
1779 -1 after a failed write
817d9f57
JH
1780
1781Used by both server-side and client-side TLS.
059ec3d9
PH
1782*/
1783
1784int
817d9f57 1785tls_write(BOOL is_server, const uschar *buff, size_t len)
059ec3d9
PH
1786{
1787int outbytes;
1788int error;
1789int left = len;
817d9f57 1790SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9 1791
c80c5570 1792DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
059ec3d9
PH
1793while (left > 0)
1794 {
c80c5570 1795 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
1796 outbytes = SSL_write(ssl, CS buff, left);
1797 error = SSL_get_error(ssl, outbytes);
1798 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1799 switch (error)
1800 {
1801 case SSL_ERROR_SSL:
1802 ERR_error_string(ERR_get_error(), ssl_errstring);
1803 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1804 return -1;
1805
1806 case SSL_ERROR_NONE:
1807 left -= outbytes;
1808 buff += outbytes;
1809 break;
1810
1811 case SSL_ERROR_ZERO_RETURN:
1812 log_write(0, LOG_MAIN, "SSL channel closed on write");
1813 return -1;
1814
817d9f57
JH
1815 case SSL_ERROR_SYSCALL:
1816 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
1817 sender_fullhost ? sender_fullhost : US"<unknown>",
1818 strerror(errno));
1819
059ec3d9
PH
1820 default:
1821 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1822 return -1;
1823 }
1824 }
1825return len;
1826}
1827
1828
1829
1830/*************************************************
1831* Close down a TLS session *
1832*************************************************/
1833
1834/* This is also called from within a delivery subprocess forked from the
1835daemon, to shut down the TLS library, without actually doing a shutdown (which
1836would tamper with the SSL session in the parent process).
1837
1838Arguments: TRUE if SSL_shutdown is to be called
1839Returns: nothing
817d9f57
JH
1840
1841Used by both server-side and client-side TLS.
059ec3d9
PH
1842*/
1843
1844void
817d9f57 1845tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 1846{
817d9f57 1847SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 1848int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
1849
1850if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
1851
1852if (shutdown)
1853 {
1854 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 1855 SSL_shutdown(*sslp);
059ec3d9
PH
1856 }
1857
817d9f57
JH
1858SSL_free(*sslp);
1859*sslp = NULL;
059ec3d9 1860
817d9f57 1861*fdp = -1;
059ec3d9
PH
1862}
1863
36f12725
NM
1864
1865
1866
1867/*************************************************
3375e053
PP
1868* Let tls_require_ciphers be checked at startup *
1869*************************************************/
1870
1871/* The tls_require_ciphers option, if set, must be something which the
1872library can parse.
1873
1874Returns: NULL on success, or error message
1875*/
1876
1877uschar *
1878tls_validate_require_cipher(void)
1879{
1880SSL_CTX *ctx;
1881uschar *s, *expciphers, *err;
1882
1883/* this duplicates from tls_init(), we need a better "init just global
1884state, for no specific purpose" singleton function of our own */
1885
1886SSL_load_error_strings();
1887OpenSSL_add_ssl_algorithms();
1888#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1889/* SHA256 is becoming ever more popular. This makes sure it gets added to the
1890list of available digests. */
1891EVP_add_digest(EVP_sha256());
1892#endif
1893
1894if (!(tls_require_ciphers && *tls_require_ciphers))
1895 return NULL;
1896
1897if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1898 return US"failed to expand tls_require_ciphers";
1899
1900if (!(expciphers && *expciphers))
1901 return NULL;
1902
1903/* normalisation ripped from above */
1904s = expciphers;
1905while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1906
1907err = NULL;
1908
1909ctx = SSL_CTX_new(SSLv23_server_method());
1910if (!ctx)
1911 {
1912 ERR_error_string(ERR_get_error(), ssl_errstring);
1913 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1914 }
1915
1916DEBUG(D_tls)
1917 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1918
1919if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1920 {
1921 ERR_error_string(ERR_get_error(), ssl_errstring);
1922 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1923 }
1924
1925SSL_CTX_free(ctx);
1926
1927return err;
1928}
1929
1930
1931
1932
1933/*************************************************
36f12725
NM
1934* Report the library versions. *
1935*************************************************/
1936
1937/* There have historically been some issues with binary compatibility in
1938OpenSSL libraries; if Exim (like many other applications) is built against
1939one version of OpenSSL but the run-time linker picks up another version,
1940it can result in serious failures, including crashing with a SIGSEGV. So
1941report the version found by the compiler and the run-time version.
1942
f64a1e23
PP
1943Note: some OS vendors backport security fixes without changing the version
1944number/string, and the version date remains unchanged. The _build_ date
1945will change, so we can more usefully assist with version diagnosis by also
1946reporting the build date.
1947
36f12725
NM
1948Arguments: a FILE* to print the results to
1949Returns: nothing
1950*/
1951
1952void
1953tls_version_report(FILE *f)
1954{
754a0503 1955fprintf(f, "Library version: OpenSSL: Compile: %s\n"
f64a1e23
PP
1956 " Runtime: %s\n"
1957 " : %s\n",
754a0503 1958 OPENSSL_VERSION_TEXT,
f64a1e23
PP
1959 SSLeay_version(SSLEAY_VERSION),
1960 SSLeay_version(SSLEAY_BUILT_ON));
1961/* third line is 38 characters for the %s and the line is 73 chars long;
1962the OpenSSL output includes a "built on: " prefix already. */
36f12725
NM
1963}
1964
9e3331ea
TK
1965
1966
1967
1968/*************************************************
17c76198 1969* Random number generation *
9e3331ea
TK
1970*************************************************/
1971
1972/* Pseudo-random number generation. The result is not expected to be
1973cryptographically strong but not so weak that someone will shoot themselves
1974in the foot using it as a nonce in input in some email header scheme or
1975whatever weirdness they'll twist this into. The result should handle fork()
1976and avoid repeating sequences. OpenSSL handles that for us.
1977
1978Arguments:
1979 max range maximum
1980Returns a random number in range [0, max-1]
1981*/
1982
1983int
17c76198 1984vaguely_random_number(int max)
9e3331ea
TK
1985{
1986unsigned int r;
1987int i, needed_len;
de6135a0
PP
1988static pid_t pidlast = 0;
1989pid_t pidnow;
9e3331ea
TK
1990uschar *p;
1991uschar smallbuf[sizeof(r)];
1992
1993if (max <= 1)
1994 return 0;
1995
de6135a0
PP
1996pidnow = getpid();
1997if (pidnow != pidlast)
1998 {
1999 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2000 is unique for each thread", this doesn't apparently apply across processes,
2001 so our own warning from vaguely_random_number_fallback() applies here too.
2002 Fix per PostgreSQL. */
2003 if (pidlast != 0)
2004 RAND_cleanup();
2005 pidlast = pidnow;
2006 }
2007
9e3331ea
TK
2008/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2009if (!RAND_status())
2010 {
2011 randstuff r;
2012 gettimeofday(&r.tv, NULL);
2013 r.p = getpid();
2014
2015 RAND_seed((uschar *)(&r), sizeof(r));
2016 }
2017/* We're after pseudo-random, not random; if we still don't have enough data
2018in the internal PRNG then our options are limited. We could sleep and hope
2019for entropy to come along (prayer technique) but if the system is so depleted
2020in the first place then something is likely to just keep taking it. Instead,
2021we'll just take whatever little bit of pseudo-random we can still manage to
2022get. */
2023
2024needed_len = sizeof(r);
2025/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2026asked for a number less than 10. */
2027for (r = max, i = 0; r; ++i)
2028 r >>= 1;
2029i = (i + 7) / 8;
2030if (i < needed_len)
2031 needed_len = i;
2032
2033/* We do not care if crypto-strong */
17c76198
PP
2034i = RAND_pseudo_bytes(smallbuf, needed_len);
2035if (i < 0)
2036 {
2037 DEBUG(D_all)
2038 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2039 return vaguely_random_number_fallback(max);
2040 }
2041
9e3331ea
TK
2042r = 0;
2043for (p = smallbuf; needed_len; --needed_len, ++p)
2044 {
2045 r *= 256;
2046 r += *p;
2047 }
2048
2049/* We don't particularly care about weighted results; if someone wants
2050smooth distribution and cares enough then they should submit a patch then. */
2051return r % max;
2052}
2053
77bb000f
PP
2054
2055
2056
2057/*************************************************
2058* OpenSSL option parse *
2059*************************************************/
2060
2061/* Parse one option for tls_openssl_options_parse below
2062
2063Arguments:
2064 name one option name
2065 value place to store a value for it
2066Returns success or failure in parsing
2067*/
2068
2069struct exim_openssl_option {
2070 uschar *name;
2071 long value;
2072};
2073/* We could use a macro to expand, but we need the ifdef and not all the
2074options document which version they were introduced in. Policylet: include
2075all options unless explicitly for DTLS, let the administrator choose which
2076to apply.
2077
2078This list is current as of:
e2fbf4a2
PP
2079 ==> 1.0.1b <==
2080Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2081*/
77bb000f
PP
2082static struct exim_openssl_option exim_openssl_options[] = {
2083/* KEEP SORTED ALPHABETICALLY! */
2084#ifdef SSL_OP_ALL
73a46702 2085 { US"all", SSL_OP_ALL },
77bb000f
PP
2086#endif
2087#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2088 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2089#endif
2090#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2091 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2092#endif
2093#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2094 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2095#endif
2096#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2097 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2098#endif
2099#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2100 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2101#endif
2102#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2103 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2104#endif
2105#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2106 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2107#endif
2108#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2109 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2110#endif
2111#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2112 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2113#endif
2114#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2115 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2116#endif
c80c5570
PP
2117#ifdef SSL_OP_NO_COMPRESSION
2118 { US"no_compression", SSL_OP_NO_COMPRESSION },
2119#endif
77bb000f 2120#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2121 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2122#endif
c0c7b2da
PP
2123#ifdef SSL_OP_NO_SSLv2
2124 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2125#endif
2126#ifdef SSL_OP_NO_SSLv3
2127 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2128#endif
2129#ifdef SSL_OP_NO_TICKET
2130 { US"no_ticket", SSL_OP_NO_TICKET },
2131#endif
2132#ifdef SSL_OP_NO_TLSv1
2133 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2134#endif
c80c5570
PP
2135#ifdef SSL_OP_NO_TLSv1_1
2136#if SSL_OP_NO_TLSv1_1 == 0x00000400L
2137 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2138#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2139#else
2140 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2141#endif
2142#endif
2143#ifdef SSL_OP_NO_TLSv1_2
2144 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2145#endif
e2fbf4a2
PP
2146#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2147 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2148#endif
77bb000f 2149#ifdef SSL_OP_SINGLE_DH_USE
73a46702 2150 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
2151#endif
2152#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 2153 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
2154#endif
2155#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 2156 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
2157#endif
2158#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 2159 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
2160#endif
2161#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 2162 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
2163#endif
2164#ifdef SSL_OP_TLS_D5_BUG
73a46702 2165 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
2166#endif
2167#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 2168 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
2169#endif
2170};
2171static int exim_openssl_options_size =
2172 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2173
c80c5570 2174
77bb000f
PP
2175static BOOL
2176tls_openssl_one_option_parse(uschar *name, long *value)
2177{
2178int first = 0;
2179int last = exim_openssl_options_size;
2180while (last > first)
2181 {
2182 int middle = (first + last)/2;
2183 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2184 if (c == 0)
2185 {
2186 *value = exim_openssl_options[middle].value;
2187 return TRUE;
2188 }
2189 else if (c > 0)
2190 first = middle + 1;
2191 else
2192 last = middle;
2193 }
2194return FALSE;
2195}
2196
2197
2198
2199
2200/*************************************************
2201* OpenSSL option parsing logic *
2202*************************************************/
2203
2204/* OpenSSL has a number of compatibility options which an administrator might
2205reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2206we look like log_selector.
2207
2208Arguments:
2209 option_spec the administrator-supplied string of options
2210 results ptr to long storage for the options bitmap
2211Returns success or failure
2212*/
2213
2214BOOL
2215tls_openssl_options_parse(uschar *option_spec, long *results)
2216{
2217long result, item;
2218uschar *s, *end;
2219uschar keep_c;
2220BOOL adding, item_parsed;
2221
0e944a0d 2222result = 0L;
b1770b6e 2223/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 2224 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
2225#ifdef SSL_OP_NO_SSLv2
2226result |= SSL_OP_NO_SSLv2;
2227#endif
77bb000f
PP
2228
2229if (option_spec == NULL)
2230 {
2231 *results = result;
2232 return TRUE;
2233 }
2234
2235for (s=option_spec; *s != '\0'; /**/)
2236 {
2237 while (isspace(*s)) ++s;
2238 if (*s == '\0')
2239 break;
2240 if (*s != '+' && *s != '-')
2241 {
2242 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 2243 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
2244 return FALSE;
2245 }
2246 adding = *s++ == '+';
2247 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2248 keep_c = *end;
2249 *end = '\0';
2250 item_parsed = tls_openssl_one_option_parse(s, &item);
2251 if (!item_parsed)
2252 {
0e944a0d 2253 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
2254 return FALSE;
2255 }
2256 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2257 adding ? "adding" : "removing", result, item, s);
2258 if (adding)
2259 result |= item;
2260 else
2261 result &= ~item;
2262 *end = keep_c;
2263 s = end;
2264 }
2265
2266*results = result;
2267return TRUE;
2268}
2269
9d1c15ef
JH
2270/* vi: aw ai sw=2
2271*/
059ec3d9 2272/* End of tls-openssl.c */