Make dmarc code c89 compliant
[exim.git] / src / src / tls-openssl.c
CommitLineData
059ec3d9
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
bc338899 5/* Copyright (c) University of Cambridge 1995 - 2013 */
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6/* See the file NOTICE for conditions of use and distribution. */
7
f5d78688
JH
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>
3f7eeb86
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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PP
34#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
35#define EXIM_HAVE_OPENSSL_TLSEXT
36#endif
37
059ec3d9
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38/* Structure for collecting random data for seeding. */
39
40typedef struct randstuff {
9e3331ea
TK
41 struct timeval tv;
42 pid_t p;
059ec3d9
PH
43} randstuff;
44
45/* Local static variables */
46
a2ff477a
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47static BOOL client_verify_callback_called = FALSE;
48static BOOL server_verify_callback_called = FALSE;
059ec3d9
PH
49static const uschar *sid_ctx = US"exim";
50
d4f09789
PP
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
817d9f57
JH
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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JH
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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JH
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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PP
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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PP
116
117static int
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JH
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{
7199e1ee
TF
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)
7199e1ee
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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PH
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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PH
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
f5d78688
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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)
059ec3d9
PH
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;
279 if (!*optionalp) return 0; /* reject */
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280 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
281 "tls_try_verify_hosts)\n");
282 return 1; /* accept */
283 }
284
285if (x509ctx->error_depth != 0)
286 {
287 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n",
288 x509ctx->error_depth, txt);
f5d78688
JH
289#ifdef EXPERIMENTAL_OCSP
290 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
291 { /* client, wanting stapling */
292 /* Add the server cert's signing chain as the one
293 for the verification of the OCSP stapled information. */
294
295 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
296 x509ctx->current_cert))
297 ERR_clear_error();
298 }
299#endif
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300 }
301else
302 {
303 DEBUG(D_tls) debug_printf("SSL%s peer: %s\n",
a2ff477a
JH
304 *calledp ? "" : " authenticated", txt);
305 tlsp->peerdn = txt;
059ec3d9
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306 }
307
f5d78688
JH
308/*XXX JGH: this looks bogus - we set "verified" first time through, which
309will be for the root CS cert (calls work down the chain). Why should it
310not be on the last call, where we're setting peerdn?
983207c1
JH
311
312To test: set up a chain anchored by a good root-CA but with a bad server cert.
313Does certificate_verified get set?
f5d78688 314*/
a2ff477a
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315if (!*calledp) tlsp->certificate_verified = TRUE;
316*calledp = TRUE;
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317
318return 1; /* accept */
319}
320
a2ff477a
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321static int
322verify_callback_client(int state, X509_STORE_CTX *x509ctx)
323{
f5d78688 324return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
a2ff477a
JH
325}
326
327static int
328verify_callback_server(int state, X509_STORE_CTX *x509ctx)
329{
f5d78688 330return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
a2ff477a
JH
331}
332
059ec3d9
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333
334
335/*************************************************
336* Information callback *
337*************************************************/
338
339/* The SSL library functions call this from time to time to indicate what they
7be682ca
PP
340are doing. We copy the string to the debugging output when TLS debugging has
341been requested.
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342
343Arguments:
344 s the SSL connection
345 where
346 ret
347
348Returns: nothing
349*/
350
351static void
352info_callback(SSL *s, int where, int ret)
353{
354where = where;
355ret = ret;
356DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
357}
358
359
360
361/*************************************************
362* Initialize for DH *
363*************************************************/
364
365/* If dhparam is set, expand it, and load up the parameters for DH encryption.
366
367Arguments:
a799883d 368 dhparam DH parameter file or fixed parameter identity string
7199e1ee 369 host connected host, if client; NULL if server
059ec3d9
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370
371Returns: TRUE if OK (nothing to set up, or setup worked)
372*/
373
374static BOOL
a799883d 375init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
059ec3d9 376{
059ec3d9
PH
377BIO *bio;
378DH *dh;
379uschar *dhexpanded;
a799883d 380const char *pem;
059ec3d9
PH
381
382if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
383 return FALSE;
384
a799883d 385if (dhexpanded == NULL || *dhexpanded == '\0')
059ec3d9 386 {
a799883d 387 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
059ec3d9 388 }
a799883d 389else if (dhexpanded[0] == '/')
059ec3d9 390 {
a799883d
PP
391 bio = BIO_new_file(CS dhexpanded, "r");
392 if (bio == NULL)
059ec3d9 393 {
7199e1ee 394 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
a799883d
PP
395 host, US strerror(errno));
396 return FALSE;
059ec3d9 397 }
a799883d
PP
398 }
399else
400 {
401 if (Ustrcmp(dhexpanded, "none") == 0)
059ec3d9 402 {
a799883d
PP
403 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
404 return TRUE;
059ec3d9 405 }
a799883d
PP
406
407 pem = std_dh_prime_named(dhexpanded);
408 if (!pem)
409 {
410 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
411 host, US strerror(errno));
412 return FALSE;
413 }
414 bio = BIO_new_mem_buf(CS pem, -1);
415 }
416
417dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
418if (dh == NULL)
419 {
059ec3d9 420 BIO_free(bio);
a799883d
PP
421 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
422 host, NULL);
423 return FALSE;
424 }
425
426/* Even if it is larger, we silently return success rather than cause things
427 * to fail out, so that a too-large DH will not knock out all TLS; it's a
428 * debatable choice. */
429if ((8*DH_size(dh)) > tls_dh_max_bits)
430 {
431 DEBUG(D_tls)
432 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
433 8*DH_size(dh), tls_dh_max_bits);
434 }
435else
436 {
437 SSL_CTX_set_tmp_dh(sctx, dh);
438 DEBUG(D_tls)
439 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
440 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
059ec3d9
PH
441 }
442
a799883d
PP
443DH_free(dh);
444BIO_free(bio);
445
446return TRUE;
059ec3d9
PH
447}
448
449
450
451
3f7eeb86
PP
452#ifdef EXPERIMENTAL_OCSP
453/*************************************************
454* Load OCSP information into state *
455*************************************************/
456
f5d78688 457/* Called to load the server OCSP response from the given file into memory, once
3f7eeb86
PP
458caller has determined this is needed. Checks validity. Debugs a message
459if invalid.
460
461ASSUMES: single response, for single cert.
462
463Arguments:
464 sctx the SSL_CTX* to update
465 cbinfo various parts of session state
466 expanded the filename putatively holding an OCSP response
467
468*/
469
470static void
f5d78688 471ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
3f7eeb86
PP
472{
473BIO *bio;
474OCSP_RESPONSE *resp;
475OCSP_BASICRESP *basic_response;
476OCSP_SINGLERESP *single_response;
477ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
478X509_STORE *store;
479unsigned long verify_flags;
480int status, reason, i;
481
f5d78688
JH
482cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
483if (cbinfo->u_ocsp.server.response)
3f7eeb86 484 {
f5d78688
JH
485 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
486 cbinfo->u_ocsp.server.response = NULL;
3f7eeb86
PP
487 }
488
f5d78688 489bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
3f7eeb86
PP
490if (!bio)
491 {
492 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
f5d78688 493 cbinfo->u_ocsp.server.file_expanded);
3f7eeb86
PP
494 return;
495 }
496
497resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
498BIO_free(bio);
499if (!resp)
500 {
501 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
502 return;
503 }
504
505status = OCSP_response_status(resp);
506if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
507 {
508 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
509 OCSP_response_status_str(status), status);
f5d78688 510 goto bad;
3f7eeb86
PP
511 }
512
513basic_response = OCSP_response_get1_basic(resp);
514if (!basic_response)
515 {
516 DEBUG(D_tls)
517 debug_printf("OCSP response parse error: unable to extract basic response.\n");
f5d78688 518 goto bad;
3f7eeb86
PP
519 }
520
521store = SSL_CTX_get_cert_store(sctx);
522verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
523
524/* May need to expose ability to adjust those flags?
525OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
526OCSP_TRUSTOTHER OCSP_NOINTERN */
527
528i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
529if (i <= 0)
530 {
531 DEBUG(D_tls) {
532 ERR_error_string(ERR_get_error(), ssl_errstring);
533 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
f5d78688
JH
534 }
535 goto bad;
3f7eeb86
PP
536 }
537
538/* Here's the simplifying assumption: there's only one response, for the
539one certificate we use, and nothing for anything else in a chain. If this
540proves false, we need to extract a cert id from our issued cert
541(tls_certificate) and use that for OCSP_resp_find_status() (which finds the
542right cert in the stack and then calls OCSP_single_get0_status()).
543
544I'm hoping to avoid reworking a bunch more of how we handle state here. */
545single_response = OCSP_resp_get0(basic_response, 0);
546if (!single_response)
547 {
548 DEBUG(D_tls)
549 debug_printf("Unable to get first response from OCSP basic response.\n");
f5d78688 550 goto bad;
3f7eeb86
PP
551 }
552
553status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
f5d78688 554if (status != V_OCSP_CERTSTATUS_GOOD)
3f7eeb86 555 {
f5d78688
JH
556 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
557 OCSP_cert_status_str(status), status,
558 OCSP_crl_reason_str(reason), reason);
559 goto bad;
3f7eeb86
PP
560 }
561
562if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
563 {
564 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
f5d78688 565 goto bad;
3f7eeb86
PP
566 }
567
f5d78688
JH
568supply_response:
569cbinfo->u_ocsp.server.response = resp;
570return;
571
572bad:
573if (running_in_test_harness)
574 {
575 extern char ** environ;
576 uschar ** p;
577 for (p = USS environ; *p != NULL; p++)
578 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
579 {
580 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
581 goto supply_response;
582 }
583 }
584return;
3f7eeb86 585}
f5d78688 586#endif /*EXPERIMENTAL_OCSP*/
3f7eeb86
PP
587
588
589
590
059ec3d9 591/*************************************************
7be682ca
PP
592* Expand key and cert file specs *
593*************************************************/
594
f5d78688 595/* Called once during tls_init and possibly again during TLS setup, for a
7be682ca
PP
596new context, if Server Name Indication was used and tls_sni was seen in
597the certificate string.
598
599Arguments:
600 sctx the SSL_CTX* to update
601 cbinfo various parts of session state
602
603Returns: OK/DEFER/FAIL
604*/
605
606static int
3f7eeb86 607tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
7be682ca
PP
608{
609uschar *expanded;
610
611if (cbinfo->certificate == NULL)
612 return OK;
613
d9b2312b
JH
614if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
615 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
616 Ustrstr(cbinfo->certificate, US"tls_out_sni")
617 )
7be682ca
PP
618 reexpand_tls_files_for_sni = TRUE;
619
620if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
621 return DEFER;
622
623if (expanded != NULL)
624 {
625 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
626 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
627 return tls_error(string_sprintf(
628 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
629 cbinfo->host, NULL);
630 }
631
632if (cbinfo->privatekey != NULL &&
633 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
634 return DEFER;
635
636/* If expansion was forced to fail, key_expanded will be NULL. If the result
637of the expansion is an empty string, ignore it also, and assume the private
638key is in the same file as the certificate. */
639
640if (expanded != NULL && *expanded != 0)
641 {
642 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
643 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
644 return tls_error(string_sprintf(
645 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
646 }
647
3f7eeb86 648#ifdef EXPERIMENTAL_OCSP
f5d78688 649if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
3f7eeb86 650 {
f5d78688 651 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
3f7eeb86
PP
652 return DEFER;
653
654 if (expanded != NULL && *expanded != 0)
655 {
656 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
f5d78688
JH
657 if (cbinfo->u_ocsp.server.file_expanded &&
658 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
3f7eeb86
PP
659 {
660 DEBUG(D_tls)
661 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
662 } else {
663 ocsp_load_response(sctx, cbinfo, expanded);
664 }
665 }
666 }
667#endif
668
7be682ca
PP
669return OK;
670}
671
672
673
674
675/*************************************************
676* Callback to handle SNI *
677*************************************************/
678
679/* Called when acting as server during the TLS session setup if a Server Name
680Indication extension was sent by the client.
681
682API documentation is OpenSSL s_server.c implementation.
683
684Arguments:
685 s SSL* of the current session
686 ad unknown (part of OpenSSL API) (unused)
687 arg Callback of "our" registered data
688
689Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
690*/
691
3bcbbbe2 692#ifdef EXIM_HAVE_OPENSSL_TLSEXT
7be682ca 693static int
7be682ca
PP
694tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
695{
696const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
3f7eeb86 697tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
7be682ca 698int rc;
3f0945ff 699int old_pool = store_pool;
7be682ca
PP
700
701if (!servername)
702 return SSL_TLSEXT_ERR_OK;
703
3f0945ff 704DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
7be682ca
PP
705 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
706
707/* Make the extension value available for expansion */
3f0945ff 708store_pool = POOL_PERM;
817d9f57 709tls_in.sni = string_copy(US servername);
3f0945ff 710store_pool = old_pool;
7be682ca
PP
711
712if (!reexpand_tls_files_for_sni)
713 return SSL_TLSEXT_ERR_OK;
714
715/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
716not confident that memcpy wouldn't break some internal reference counting.
717Especially since there's a references struct member, which would be off. */
718
817d9f57
JH
719server_sni = SSL_CTX_new(SSLv23_server_method());
720if (!server_sni)
7be682ca
PP
721 {
722 ERR_error_string(ERR_get_error(), ssl_errstring);
723 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
724 return SSL_TLSEXT_ERR_NOACK;
725 }
726
727/* Not sure how many of these are actually needed, since SSL object
728already exists. Might even need this selfsame callback, for reneg? */
729
817d9f57
JH
730SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
731SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
732SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
733SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
734SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
735SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
7be682ca 736if (cbinfo->server_cipher_list)
817d9f57 737 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
3f7eeb86 738#ifdef EXPERIMENTAL_OCSP
f5d78688 739if (cbinfo->u_ocsp.server.file)
3f7eeb86 740 {
f5d78688 741 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
14c7b357 742 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
3f7eeb86
PP
743 }
744#endif
7be682ca 745
983207c1 746rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
7be682ca
PP
747if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
748
3f7eeb86
PP
749/* do this after setup_certs, because this can require the certs for verifying
750OCSP information. */
817d9f57 751rc = tls_expand_session_files(server_sni, cbinfo);
7be682ca
PP
752if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
753
389ca47a 754rc = init_dh(server_sni, cbinfo->dhparam, NULL);
a799883d
PP
755if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
756
7be682ca 757DEBUG(D_tls) debug_printf("Switching SSL context.\n");
817d9f57 758SSL_set_SSL_CTX(s, server_sni);
7be682ca
PP
759
760return SSL_TLSEXT_ERR_OK;
761}
3bcbbbe2 762#endif /* EXIM_HAVE_OPENSSL_TLSEXT */
7be682ca
PP
763
764
765
766
3f7eeb86 767#ifdef EXPERIMENTAL_OCSP
f5d78688 768
3f7eeb86
PP
769/*************************************************
770* Callback to handle OCSP Stapling *
771*************************************************/
772
773/* Called when acting as server during the TLS session setup if the client
774requests OCSP information with a Certificate Status Request.
775
776Documentation via openssl s_server.c and the Apache patch from the OpenSSL
777project.
778
779*/
780
781static int
f5d78688 782tls_server_stapling_cb(SSL *s, void *arg)
3f7eeb86
PP
783{
784const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
785uschar *response_der;
786int response_der_len;
787
f5d78688
JH
788if (log_extra_selector & LX_tls_cipher)
789 log_write(0, LOG_MAIN, "[%s] Recieved OCSP stapling req;%s responding",
790 sender_host_address, cbinfo->u_ocsp.server.response ? "":" not");
791else
792 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.",
793 cbinfo->u_ocsp.server.response ? "have" : "lack");
794
795if (!cbinfo->u_ocsp.server.response)
3f7eeb86
PP
796 return SSL_TLSEXT_ERR_NOACK;
797
798response_der = NULL;
f5d78688 799response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, &response_der);
3f7eeb86
PP
800if (response_der_len <= 0)
801 return SSL_TLSEXT_ERR_NOACK;
802
5e55c7a9 803SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
3f7eeb86
PP
804return SSL_TLSEXT_ERR_OK;
805}
806
3f7eeb86 807
f5d78688
JH
808static void
809time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
810{
811BIO_printf(bp, "\t%s: ", str);
812ASN1_GENERALIZEDTIME_print(bp, time);
813BIO_puts(bp, "\n");
814}
815
816static int
817tls_client_stapling_cb(SSL *s, void *arg)
818{
819tls_ext_ctx_cb * cbinfo = arg;
820const unsigned char * p;
821int len;
822OCSP_RESPONSE * rsp;
823OCSP_BASICRESP * bs;
824int i;
825
826DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
827len = SSL_get_tlsext_status_ocsp_resp(s, &p);
828if(!p)
829 {
830 if (log_extra_selector & LX_tls_cipher)
831 log_write(0, LOG_MAIN, "Received TLS status response, null content");
832 else
833 DEBUG(D_tls) debug_printf(" null\n");
834 return 0; /* This is the fail case for require-ocsp; none from server */
835 }
836if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
837 {
838 if (log_extra_selector & LX_tls_cipher)
839 log_write(0, LOG_MAIN, "Received TLS status response, parse error");
840 else
841 DEBUG(D_tls) debug_printf(" parse error\n");
842 return 0;
843 }
844
845if(!(bs = OCSP_response_get1_basic(rsp)))
846 {
847 if (log_extra_selector & LX_tls_cipher)
848 log_write(0, LOG_MAIN, "Received TLS status response, error parsing response");
849 else
850 DEBUG(D_tls) debug_printf(" error parsing response\n");
851 OCSP_RESPONSE_free(rsp);
852 return 0;
853 }
854
855/* We'd check the nonce here if we'd put one in the request. */
856/* However that would defeat cacheability on the server so we don't. */
857
858
859/* This section of code reworked from OpenSSL apps source;
860 The OpenSSL Project retains copyright:
861 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
862*/
863 {
864 BIO * bp = NULL;
865 OCSP_CERTID *id;
866 int status, reason;
867 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
868
869 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
870
871 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
872
873 /* Use the chain that verified the server cert to verify the stapled info */
874 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
875
876 if ((i = OCSP_basic_verify(bs, NULL, cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
877 {
878 BIO_printf(bp, "OCSP response verify failure\n");
879 ERR_print_errors(bp);
880 i = 0;
881 goto out;
882 }
883
884 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
885
886 {
887 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
888 OCSP_SINGLERESP * single;
889
890 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
891 {
892 log_write(0, LOG_MAIN, "OCSP stapling with multiple responses not handled");
893 goto out;
894 }
895 single = OCSP_resp_get0(bs, 0);
896 status = OCSP_single_get0_status(single, &reason, &rev, &thisupd, &nextupd);
897 }
898
899 i = 0;
900 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
901 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
902 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
903 {
904 DEBUG(D_tls) ERR_print_errors(bp);
905 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
906 goto out;
907 }
908
909 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", OCSP_cert_status_str(status));
910 switch(status)
911 {
912 case V_OCSP_CERTSTATUS_GOOD:
913 i = 1;
914 break;
915 case V_OCSP_CERTSTATUS_REVOKED:
916 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
917 reason != -1 ? "; reason: " : "", reason != -1 ? OCSP_crl_reason_str(reason) : "");
918 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
919 i = 0;
920 break;
921 default:
922 log_write(0, LOG_MAIN, "Server certificate status unknown, in OCSP stapling");
923 i = 0;
924 break;
925 }
926 out:
927 BIO_free(bp);
928 }
929
930OCSP_RESPONSE_free(rsp);
931return i;
932}
933#endif /*EXPERIMENTAL_OCSP*/
3f7eeb86
PP
934
935
936
7be682ca 937/*************************************************
059ec3d9
PH
938* Initialize for TLS *
939*************************************************/
940
941/* Called from both server and client code, to do preliminary initialization of
942the library.
943
944Arguments:
945 host connected host, if client; NULL if server
946 dhparam DH parameter file
947 certificate certificate file
948 privatekey private key
f5d78688 949 ocsp_file file of stapling info (server); flag for require ocsp (client)
059ec3d9
PH
950 addr address if client; NULL if server (for some randomness)
951
952Returns: OK/DEFER/FAIL
953*/
954
955static int
817d9f57 956tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
3f7eeb86
PP
957 uschar *privatekey,
958#ifdef EXPERIMENTAL_OCSP
959 uschar *ocsp_file,
960#endif
817d9f57 961 address_item *addr, tls_ext_ctx_cb ** cbp)
059ec3d9 962{
77bb000f 963long init_options;
7be682ca 964int rc;
77bb000f 965BOOL okay;
7be682ca
PP
966tls_ext_ctx_cb *cbinfo;
967
968cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
969cbinfo->certificate = certificate;
970cbinfo->privatekey = privatekey;
3f7eeb86 971#ifdef EXPERIMENTAL_OCSP
f5d78688
JH
972if ((cbinfo->is_server = host==NULL))
973 {
974 cbinfo->u_ocsp.server.file = ocsp_file;
975 cbinfo->u_ocsp.server.file_expanded = NULL;
976 cbinfo->u_ocsp.server.response = NULL;
977 }
978else
979 cbinfo->u_ocsp.client.verify_store = NULL;
3f7eeb86 980#endif
7be682ca
PP
981cbinfo->dhparam = dhparam;
982cbinfo->host = host;
77bb000f 983
059ec3d9
PH
984SSL_load_error_strings(); /* basic set up */
985OpenSSL_add_ssl_algorithms();
986
388d6564 987#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
77bb000f 988/* SHA256 is becoming ever more popular. This makes sure it gets added to the
a0475b69
TK
989list of available digests. */
990EVP_add_digest(EVP_sha256());
cf1ef1a9 991#endif
a0475b69 992
f0f5a555
PP
993/* Create a context.
994The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
995negotiation in the different methods; as far as I can tell, the only
996*_{server,client}_method which allows negotiation is SSLv23, which exists even
997when OpenSSL is built without SSLv2 support.
998By disabling with openssl_options, we can let admins re-enable with the
999existing knob. */
059ec3d9 1000
817d9f57 1001*ctxp = SSL_CTX_new((host == NULL)?
059ec3d9
PH
1002 SSLv23_server_method() : SSLv23_client_method());
1003
817d9f57 1004if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
059ec3d9
PH
1005
1006/* It turns out that we need to seed the random number generator this early in
1007order to get the full complement of ciphers to work. It took me roughly a day
1008of work to discover this by experiment.
1009
1010On systems that have /dev/urandom, SSL may automatically seed itself from
1011there. Otherwise, we have to make something up as best we can. Double check
1012afterwards. */
1013
1014if (!RAND_status())
1015 {
1016 randstuff r;
9e3331ea 1017 gettimeofday(&r.tv, NULL);
059ec3d9
PH
1018 r.p = getpid();
1019
1020 RAND_seed((uschar *)(&r), sizeof(r));
1021 RAND_seed((uschar *)big_buffer, big_buffer_size);
1022 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1023
1024 if (!RAND_status())
7199e1ee 1025 return tls_error(US"RAND_status", host,
5ca6d115 1026 US"unable to seed random number generator");
059ec3d9
PH
1027 }
1028
1029/* Set up the information callback, which outputs if debugging is at a suitable
1030level. */
1031
817d9f57 1032SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
059ec3d9 1033
c80c5570 1034/* Automatically re-try reads/writes after renegotiation. */
817d9f57 1035(void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
c80c5570 1036
77bb000f
PP
1037/* Apply administrator-supplied work-arounds.
1038Historically we applied just one requested option,
1039SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1040moved to an administrator-controlled list of options to specify and
1041grandfathered in the first one as the default value for "openssl_options".
059ec3d9 1042
77bb000f
PP
1043No OpenSSL version number checks: the options we accept depend upon the
1044availability of the option value macros from OpenSSL. */
059ec3d9 1045
77bb000f
PP
1046okay = tls_openssl_options_parse(openssl_options, &init_options);
1047if (!okay)
73a46702 1048 return tls_error(US"openssl_options parsing failed", host, NULL);
77bb000f
PP
1049
1050if (init_options)
1051 {
1052 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
817d9f57 1053 if (!(SSL_CTX_set_options(*ctxp, init_options)))
77bb000f
PP
1054 return tls_error(string_sprintf(
1055 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1056 }
1057else
1058 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
059ec3d9
PH
1059
1060/* Initialize with DH parameters if supplied */
1061
817d9f57 1062if (!init_dh(*ctxp, dhparam, host)) return DEFER;
059ec3d9 1063
3f7eeb86 1064/* Set up certificate and key (and perhaps OCSP info) */
059ec3d9 1065
817d9f57 1066rc = tls_expand_session_files(*ctxp, cbinfo);
7be682ca 1067if (rc != OK) return rc;
c91535f3 1068
7be682ca 1069/* If we need to handle SNI, do so */
3bcbbbe2 1070#ifdef EXIM_HAVE_OPENSSL_TLSEXT
f5d78688 1071if (host == NULL) /* server */
3f0945ff 1072 {
f5d78688
JH
1073# ifdef EXPERIMENTAL_OCSP
1074 /* We check u_ocsp.server.file, not server.response, because we care about if
3f7eeb86
PP
1075 the option exists, not what the current expansion might be, as SNI might
1076 change the certificate and OCSP file in use between now and the time the
1077 callback is invoked. */
f5d78688 1078 if (cbinfo->u_ocsp.server.file)
3f7eeb86 1079 {
f5d78688 1080 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
5e55c7a9 1081 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
3f7eeb86 1082 }
f5d78688 1083# endif
3f0945ff
PP
1084 /* We always do this, so that $tls_sni is available even if not used in
1085 tls_certificate */
817d9f57
JH
1086 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1087 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
3f0945ff 1088 }
f5d78688
JH
1089# ifdef EXPERIMENTAL_OCSP
1090else /* client */
1091 if(ocsp_file) /* wanting stapling */
1092 {
1093 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1094 {
1095 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1096 return FAIL;
1097 }
1098 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1099 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1100 }
1101# endif
7be682ca 1102#endif
059ec3d9
PH
1103
1104/* Set up the RSA callback */
1105
817d9f57 1106SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
059ec3d9
PH
1107
1108/* Finally, set the timeout, and we are done */
1109
817d9f57 1110SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
059ec3d9 1111DEBUG(D_tls) debug_printf("Initialized TLS\n");
7be682ca 1112
817d9f57 1113*cbp = cbinfo;
7be682ca 1114
059ec3d9
PH
1115return OK;
1116}
1117
1118
1119
1120
1121/*************************************************
1122* Get name of cipher in use *
1123*************************************************/
1124
817d9f57 1125/*
059ec3d9 1126Argument: pointer to an SSL structure for the connection
817d9f57
JH
1127 buffer to use for answer
1128 size of buffer
1129 pointer to number of bits for cipher
059ec3d9
PH
1130Returns: nothing
1131*/
1132
1133static void
817d9f57 1134construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
059ec3d9 1135{
57b3a7f5
PP
1136/* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1137yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1138the accessor functions use const in the prototype. */
1139const SSL_CIPHER *c;
d9784128 1140const uschar *ver;
059ec3d9 1141
d9784128 1142ver = (const uschar *)SSL_get_version(ssl);
059ec3d9 1143
57b3a7f5 1144c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1145SSL_CIPHER_get_bits(c, bits);
059ec3d9 1146
817d9f57
JH
1147string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1148 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1149
1150DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1151}
1152
1153
1154
1155
1156
1157/*************************************************
1158* Set up for verifying certificates *
1159*************************************************/
1160
1161/* Called by both client and server startup
1162
1163Arguments:
7be682ca 1164 sctx SSL_CTX* to initialise
059ec3d9
PH
1165 certs certs file or NULL
1166 crl CRL file or NULL
1167 host NULL in a server; the remote host in a client
1168 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1169 otherwise passed as FALSE
983207c1 1170 cert_vfy_cb Callback function for certificate verification
059ec3d9
PH
1171
1172Returns: OK/DEFER/FAIL
1173*/
1174
1175static int
983207c1
JH
1176setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1177 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
059ec3d9
PH
1178{
1179uschar *expcerts, *expcrl;
1180
1181if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1182 return DEFER;
1183
26e72755 1184if (expcerts != NULL && *expcerts != '\0')
059ec3d9
PH
1185 {
1186 struct stat statbuf;
7be682ca 1187 if (!SSL_CTX_set_default_verify_paths(sctx))
7199e1ee 1188 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
059ec3d9
PH
1189
1190 if (Ustat(expcerts, &statbuf) < 0)
1191 {
1192 log_write(0, LOG_MAIN|LOG_PANIC,
1193 "failed to stat %s for certificates", expcerts);
1194 return DEFER;
1195 }
1196 else
1197 {
1198 uschar *file, *dir;
1199 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1200 { file = NULL; dir = expcerts; }
1201 else
1202 { file = expcerts; dir = NULL; }
1203
1204 /* If a certificate file is empty, the next function fails with an
1205 unhelpful error message. If we skip it, we get the correct behaviour (no
1206 certificates are recognized, but the error message is still misleading (it
1207 says no certificate was supplied.) But this is better. */
1208
1209 if ((file == NULL || statbuf.st_size > 0) &&
7be682ca 1210 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
7199e1ee 1211 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
059ec3d9
PH
1212
1213 if (file != NULL)
1214 {
7be682ca 1215 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
059ec3d9
PH
1216 }
1217 }
1218
1219 /* Handle a certificate revocation list. */
1220
1221 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1222
8b417f2c
PH
1223 /* This bit of code is now the version supplied by Lars Mainka. (I have
1224 * merely reformatted it into the Exim code style.)
1225
1226 * "From here I changed the code to add support for multiple crl's
1227 * in pem format in one file or to support hashed directory entries in
1228 * pem format instead of a file. This method now uses the library function
1229 * X509_STORE_load_locations to add the CRL location to the SSL context.
1230 * OpenSSL will then handle the verify against CA certs and CRLs by
1231 * itself in the verify callback." */
1232
059ec3d9
PH
1233 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1234 if (expcrl != NULL && *expcrl != 0)
1235 {
8b417f2c
PH
1236 struct stat statbufcrl;
1237 if (Ustat(expcrl, &statbufcrl) < 0)
1238 {
1239 log_write(0, LOG_MAIN|LOG_PANIC,
1240 "failed to stat %s for certificates revocation lists", expcrl);
1241 return DEFER;
1242 }
1243 else
059ec3d9 1244 {
8b417f2c
PH
1245 /* is it a file or directory? */
1246 uschar *file, *dir;
7be682ca 1247 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1248 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1249 {
8b417f2c
PH
1250 file = NULL;
1251 dir = expcrl;
1252 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1253 }
1254 else
1255 {
8b417f2c
PH
1256 file = expcrl;
1257 dir = NULL;
1258 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1259 }
8b417f2c 1260 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
7199e1ee 1261 return tls_error(US"X509_STORE_load_locations", host, NULL);
8b417f2c
PH
1262
1263 /* setting the flags to check against the complete crl chain */
1264
1265 X509_STORE_set_flags(cvstore,
1266 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1267 }
059ec3d9
PH
1268 }
1269
1270 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1271
1272 /* If verification is optional, don't fail if no certificate */
1273
7be682ca 1274 SSL_CTX_set_verify(sctx,
059ec3d9 1275 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1276 cert_vfy_cb);
059ec3d9
PH
1277 }
1278
1279return OK;
1280}
1281
1282
1283
1284/*************************************************
1285* Start a TLS session in a server *
1286*************************************************/
1287
1288/* This is called when Exim is running as a server, after having received
1289the STARTTLS command. It must respond to that command, and then negotiate
1290a TLS session.
1291
1292Arguments:
1293 require_ciphers allowed ciphers
1294
1295Returns: OK on success
1296 DEFER for errors before the start of the negotiation
1297 FAIL for errors during the negotation; the server can't
1298 continue running.
1299*/
1300
1301int
17c76198 1302tls_server_start(const uschar *require_ciphers)
059ec3d9
PH
1303{
1304int rc;
1305uschar *expciphers;
7be682ca 1306tls_ext_ctx_cb *cbinfo;
817d9f57 1307static uschar cipherbuf[256];
059ec3d9
PH
1308
1309/* Check for previous activation */
1310
817d9f57 1311if (tls_in.active >= 0)
059ec3d9 1312 {
5ca6d115 1313 tls_error(US"STARTTLS received after TLS started", NULL, US"");
059ec3d9
PH
1314 smtp_printf("554 Already in TLS\r\n");
1315 return FAIL;
1316 }
1317
1318/* Initialize the SSL library. If it fails, it will already have logged
1319the error. */
1320
817d9f57 1321rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
3f7eeb86
PP
1322#ifdef EXPERIMENTAL_OCSP
1323 tls_ocsp_file,
1324#endif
817d9f57 1325 NULL, &server_static_cbinfo);
059ec3d9 1326if (rc != OK) return rc;
817d9f57 1327cbinfo = server_static_cbinfo;
059ec3d9
PH
1328
1329if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1330 return FAIL;
1331
1332/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1333were historically separated by underscores. So that I can use either form in my
1334tests, and also for general convenience, we turn underscores into hyphens here.
1335*/
059ec3d9
PH
1336
1337if (expciphers != NULL)
1338 {
1339 uschar *s = expciphers;
1340 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1341 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1342 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
7199e1ee 1343 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
7be682ca 1344 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1345 }
1346
1347/* If this is a host for which certificate verification is mandatory or
1348optional, set up appropriately. */
1349
817d9f57 1350tls_in.certificate_verified = FALSE;
a2ff477a 1351server_verify_callback_called = FALSE;
059ec3d9
PH
1352
1353if (verify_check_host(&tls_verify_hosts) == OK)
1354 {
983207c1
JH
1355 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1356 FALSE, verify_callback_server);
059ec3d9 1357 if (rc != OK) return rc;
a2ff477a 1358 server_verify_optional = FALSE;
059ec3d9
PH
1359 }
1360else if (verify_check_host(&tls_try_verify_hosts) == OK)
1361 {
983207c1
JH
1362 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1363 TRUE, verify_callback_server);
059ec3d9 1364 if (rc != OK) return rc;
a2ff477a 1365 server_verify_optional = TRUE;
059ec3d9
PH
1366 }
1367
1368/* Prepare for new connection */
1369
817d9f57 1370if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
da3ad30d
PP
1371
1372/* Warning: we used to SSL_clear(ssl) here, it was removed.
1373 *
1374 * With the SSL_clear(), we get strange interoperability bugs with
1375 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1376 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1377 *
1378 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1379 * session shutdown. In this case, we have a brand new object and there's no
1380 * obvious reason to immediately clear it. I'm guessing that this was
1381 * originally added because of incomplete initialisation which the clear fixed,
1382 * in some historic release.
1383 */
059ec3d9
PH
1384
1385/* Set context and tell client to go ahead, except in the case of TLS startup
1386on connection, where outputting anything now upsets the clients and tends to
1387make them disconnect. We need to have an explicit fflush() here, to force out
1388the response. Other smtp_printf() calls do not need it, because in non-TLS
1389mode, the fflush() happens when smtp_getc() is called. */
1390
817d9f57
JH
1391SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1392if (!tls_in.on_connect)
059ec3d9
PH
1393 {
1394 smtp_printf("220 TLS go ahead\r\n");
1395 fflush(smtp_out);
1396 }
1397
1398/* Now negotiate the TLS session. We put our own timer on it, since it seems
1399that the OpenSSL library doesn't. */
1400
817d9f57
JH
1401SSL_set_wfd(server_ssl, fileno(smtp_out));
1402SSL_set_rfd(server_ssl, fileno(smtp_in));
1403SSL_set_accept_state(server_ssl);
059ec3d9
PH
1404
1405DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1406
1407sigalrm_seen = FALSE;
1408if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 1409rc = SSL_accept(server_ssl);
059ec3d9
PH
1410alarm(0);
1411
1412if (rc <= 0)
1413 {
7199e1ee 1414 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
77bb000f
PP
1415 if (ERR_get_error() == 0)
1416 log_write(0, LOG_MAIN,
a053d125 1417 "TLS client disconnected cleanly (rejected our certificate?)");
059ec3d9
PH
1418 return FAIL;
1419 }
1420
1421DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1422
1423/* TLS has been set up. Adjust the input functions to read via TLS,
1424and initialize things. */
1425
817d9f57
JH
1426construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1427tls_in.cipher = cipherbuf;
059ec3d9
PH
1428
1429DEBUG(D_tls)
1430 {
1431 uschar buf[2048];
817d9f57 1432 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
1433 debug_printf("Shared ciphers: %s\n", buf);
1434 }
1435
1436
817d9f57
JH
1437/* Only used by the server-side tls (tls_in), including tls_getc.
1438 Client-side (tls_out) reads (seem to?) go via
1439 smtp_read_response()/ip_recv().
1440 Hence no need to duplicate for _in and _out.
1441 */
059ec3d9
PH
1442ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1443ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1444ssl_xfer_eof = ssl_xfer_error = 0;
1445
1446receive_getc = tls_getc;
1447receive_ungetc = tls_ungetc;
1448receive_feof = tls_feof;
1449receive_ferror = tls_ferror;
58eb016e 1450receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 1451
817d9f57 1452tls_in.active = fileno(smtp_out);
059ec3d9
PH
1453return OK;
1454}
1455
1456
1457
1458
1459
1460/*************************************************
1461* Start a TLS session in a client *
1462*************************************************/
1463
1464/* Called from the smtp transport after STARTTLS has been accepted.
1465
1466Argument:
1467 fd the fd of the connection
1468 host connected host (for messages)
83da1223 1469 addr the first address
059ec3d9
PH
1470 certificate certificate file
1471 privatekey private key file
3f0945ff 1472 sni TLS SNI to send to remote host
059ec3d9
PH
1473 verify_certs file for certificate verify
1474 crl file containing CRL
1475 require_ciphers list of allowed ciphers
54c90be1
PP
1476 dh_min_bits minimum number of bits acceptable in server's DH prime
1477 (unused in OpenSSL)
83da1223 1478 timeout startup timeout
a63be306
WB
1479 verify_hosts mandatory client verification
1480 try_verify_hosts optional client verification
059ec3d9
PH
1481
1482Returns: OK on success
1483 FAIL otherwise - note that tls_error() will not give DEFER
1484 because this is not a server
1485*/
1486
1487int
f5d78688 1488tls_client_start(int fd, host_item *host, address_item *addr,
3f0945ff
PP
1489 uschar *certificate, uschar *privatekey, uschar *sni,
1490 uschar *verify_certs, uschar *crl,
f5d78688
JH
1491 uschar *require_ciphers,
1492#ifdef EXPERIMENTAL_OCSP
1493 uschar *hosts_require_ocsp,
1494#endif
a63be306
WB
1495 int dh_min_bits ARG_UNUSED, int timeout,
1496 uschar *verify_hosts, uschar *try_verify_hosts)
059ec3d9
PH
1497{
1498static uschar txt[256];
1499uschar *expciphers;
1500X509* server_cert;
1501int rc;
817d9f57 1502static uschar cipherbuf[256];
f5d78688
JH
1503#ifdef EXPERIMENTAL_OCSP
1504BOOL require_ocsp = verify_check_this_host(&hosts_require_ocsp,
1505 NULL, host->name, host->address, NULL) == OK;
1506#endif
059ec3d9 1507
f5d78688 1508rc = tls_init(&client_ctx, host, NULL, certificate, privatekey,
3f7eeb86 1509#ifdef EXPERIMENTAL_OCSP
f5d78688 1510 require_ocsp ? US"" : NULL,
3f7eeb86 1511#endif
817d9f57 1512 addr, &client_static_cbinfo);
059ec3d9
PH
1513if (rc != OK) return rc;
1514
817d9f57 1515tls_out.certificate_verified = FALSE;
a2ff477a 1516client_verify_callback_called = FALSE;
059ec3d9
PH
1517
1518if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1519 return FAIL;
1520
1521/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1522are separated by underscores. So that I can use either form in my tests, and
1523also for general convenience, we turn underscores into hyphens here. */
1524
1525if (expciphers != NULL)
1526 {
1527 uschar *s = expciphers;
1528 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1529 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1530 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
7199e1ee 1531 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
059ec3d9
PH
1532 }
1533
a63be306
WB
1534/* stick to the old behaviour for compatibility if tls_verify_certificates is
1535 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1536 the specified host patterns if one of them is defined */
1537if (((verify_hosts == NULL) && (try_verify_hosts == NULL)) ||
1538 (verify_check_host(&verify_hosts) == OK))
1539 {
1540 rc = setup_certs(client_ctx, verify_certs, crl, host, FALSE, verify_callback_client);
1541 if (rc != OK) return rc;
1542 client_verify_optional = FALSE;
1543 }
1544else if (verify_check_host(&try_verify_hosts) == OK)
1545 {
1546 rc = setup_certs(client_ctx, verify_certs, crl, host, TRUE, verify_callback_client);
1547 if (rc != OK) return rc;
1548 client_verify_optional = TRUE;
1549 }
059ec3d9 1550
817d9f57
JH
1551if ((client_ssl = SSL_new(client_ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1552SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1553SSL_set_fd(client_ssl, fd);
1554SSL_set_connect_state(client_ssl);
059ec3d9 1555
3f0945ff
PP
1556if (sni)
1557 {
817d9f57 1558 if (!expand_check(sni, US"tls_sni", &tls_out.sni))
3f0945ff 1559 return FAIL;
ec4b68e5 1560 if (tls_out.sni == NULL)
2c9a0e86
PP
1561 {
1562 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1563 }
ec4b68e5 1564 else if (!Ustrlen(tls_out.sni))
817d9f57 1565 tls_out.sni = NULL;
3f0945ff
PP
1566 else
1567 {
35731706 1568#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
1569 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1570 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706
PP
1571#else
1572 DEBUG(D_tls)
1573 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
02d9264f 1574 tls_out.sni);
35731706 1575#endif
3f0945ff
PP
1576 }
1577 }
1578
f5d78688
JH
1579#ifdef EXPERIMENTAL_OCSP
1580/* Request certificate status at connection-time. If the server
1581does OCSP stapling we will get the callback (set in tls_init()) */
1582if (require_ocsp)
1583 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1584#endif
1585
059ec3d9
PH
1586/* There doesn't seem to be a built-in timeout on connection. */
1587
1588DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1589sigalrm_seen = FALSE;
1590alarm(timeout);
817d9f57 1591rc = SSL_connect(client_ssl);
059ec3d9
PH
1592alarm(0);
1593
1594if (rc <= 0)
7199e1ee 1595 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
059ec3d9
PH
1596
1597DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1598
453a6645 1599/* Beware anonymous ciphers which lead to server_cert being NULL */
817d9f57 1600server_cert = SSL_get_peer_certificate (client_ssl);
453a6645
PP
1601if (server_cert)
1602 {
817d9f57 1603 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
453a6645 1604 CS txt, sizeof(txt));
817d9f57 1605 tls_out.peerdn = txt;
453a6645
PP
1606 }
1607else
817d9f57 1608 tls_out.peerdn = NULL;
059ec3d9 1609
817d9f57
JH
1610construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1611tls_out.cipher = cipherbuf;
059ec3d9 1612
817d9f57 1613tls_out.active = fd;
059ec3d9
PH
1614return OK;
1615}
1616
1617
1618
1619
1620
1621/*************************************************
1622* TLS version of getc *
1623*************************************************/
1624
1625/* This gets the next byte from the TLS input buffer. If the buffer is empty,
1626it refills the buffer via the SSL reading function.
1627
1628Arguments: none
1629Returns: the next character or EOF
817d9f57
JH
1630
1631Only used by the server-side TLS.
059ec3d9
PH
1632*/
1633
1634int
1635tls_getc(void)
1636{
1637if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1638 {
1639 int error;
1640 int inbytes;
1641
817d9f57 1642 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
c80c5570 1643 ssl_xfer_buffer, ssl_xfer_buffer_size);
059ec3d9
PH
1644
1645 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57
JH
1646 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1647 error = SSL_get_error(server_ssl, inbytes);
059ec3d9
PH
1648 alarm(0);
1649
1650 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1651 closed down, not that the socket itself has been closed down. Revert to
1652 non-SSL handling. */
1653
1654 if (error == SSL_ERROR_ZERO_RETURN)
1655 {
1656 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1657
1658 receive_getc = smtp_getc;
1659 receive_ungetc = smtp_ungetc;
1660 receive_feof = smtp_feof;
1661 receive_ferror = smtp_ferror;
58eb016e 1662 receive_smtp_buffered = smtp_buffered;
059ec3d9 1663
817d9f57
JH
1664 SSL_free(server_ssl);
1665 server_ssl = NULL;
1666 tls_in.active = -1;
1667 tls_in.bits = 0;
1668 tls_in.cipher = NULL;
1669 tls_in.peerdn = NULL;
1670 tls_in.sni = NULL;
059ec3d9
PH
1671
1672 return smtp_getc();
1673 }
1674
1675 /* Handle genuine errors */
1676
ba084640
PP
1677 else if (error == SSL_ERROR_SSL)
1678 {
1679 ERR_error_string(ERR_get_error(), ssl_errstring);
89dd51cd 1680 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
ba084640
PP
1681 ssl_xfer_error = 1;
1682 return EOF;
1683 }
1684
059ec3d9
PH
1685 else if (error != SSL_ERROR_NONE)
1686 {
1687 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1688 ssl_xfer_error = 1;
1689 return EOF;
1690 }
c80c5570 1691
80a47a2c
TK
1692#ifndef DISABLE_DKIM
1693 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1694#endif
059ec3d9
PH
1695 ssl_xfer_buffer_hwm = inbytes;
1696 ssl_xfer_buffer_lwm = 0;
1697 }
1698
1699/* Something in the buffer; return next uschar */
1700
1701return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1702}
1703
1704
1705
1706/*************************************************
1707* Read bytes from TLS channel *
1708*************************************************/
1709
1710/*
1711Arguments:
1712 buff buffer of data
1713 len size of buffer
1714
1715Returns: the number of bytes read
1716 -1 after a failed read
817d9f57
JH
1717
1718Only used by the client-side TLS.
059ec3d9
PH
1719*/
1720
1721int
389ca47a 1722tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 1723{
389ca47a 1724SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
1725int inbytes;
1726int error;
1727
389ca47a 1728DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 1729 buff, (unsigned int)len);
059ec3d9 1730
389ca47a
JH
1731inbytes = SSL_read(ssl, CS buff, len);
1732error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
1733
1734if (error == SSL_ERROR_ZERO_RETURN)
1735 {
1736 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1737 return -1;
1738 }
1739else if (error != SSL_ERROR_NONE)
1740 {
1741 return -1;
1742 }
1743
1744return inbytes;
1745}
1746
1747
1748
1749
1750
1751/*************************************************
1752* Write bytes down TLS channel *
1753*************************************************/
1754
1755/*
1756Arguments:
817d9f57 1757 is_server channel specifier
059ec3d9
PH
1758 buff buffer of data
1759 len number of bytes
1760
1761Returns: the number of bytes after a successful write,
1762 -1 after a failed write
817d9f57
JH
1763
1764Used by both server-side and client-side TLS.
059ec3d9
PH
1765*/
1766
1767int
817d9f57 1768tls_write(BOOL is_server, const uschar *buff, size_t len)
059ec3d9
PH
1769{
1770int outbytes;
1771int error;
1772int left = len;
817d9f57 1773SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9 1774
c80c5570 1775DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
059ec3d9
PH
1776while (left > 0)
1777 {
c80c5570 1778 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
1779 outbytes = SSL_write(ssl, CS buff, left);
1780 error = SSL_get_error(ssl, outbytes);
1781 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1782 switch (error)
1783 {
1784 case SSL_ERROR_SSL:
1785 ERR_error_string(ERR_get_error(), ssl_errstring);
1786 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1787 return -1;
1788
1789 case SSL_ERROR_NONE:
1790 left -= outbytes;
1791 buff += outbytes;
1792 break;
1793
1794 case SSL_ERROR_ZERO_RETURN:
1795 log_write(0, LOG_MAIN, "SSL channel closed on write");
1796 return -1;
1797
817d9f57
JH
1798 case SSL_ERROR_SYSCALL:
1799 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
1800 sender_fullhost ? sender_fullhost : US"<unknown>",
1801 strerror(errno));
1802
059ec3d9
PH
1803 default:
1804 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1805 return -1;
1806 }
1807 }
1808return len;
1809}
1810
1811
1812
1813/*************************************************
1814* Close down a TLS session *
1815*************************************************/
1816
1817/* This is also called from within a delivery subprocess forked from the
1818daemon, to shut down the TLS library, without actually doing a shutdown (which
1819would tamper with the SSL session in the parent process).
1820
1821Arguments: TRUE if SSL_shutdown is to be called
1822Returns: nothing
817d9f57
JH
1823
1824Used by both server-side and client-side TLS.
059ec3d9
PH
1825*/
1826
1827void
817d9f57 1828tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 1829{
817d9f57 1830SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 1831int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
1832
1833if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
1834
1835if (shutdown)
1836 {
1837 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 1838 SSL_shutdown(*sslp);
059ec3d9
PH
1839 }
1840
817d9f57
JH
1841SSL_free(*sslp);
1842*sslp = NULL;
059ec3d9 1843
817d9f57 1844*fdp = -1;
059ec3d9
PH
1845}
1846
36f12725
NM
1847
1848
1849
1850/*************************************************
3375e053
PP
1851* Let tls_require_ciphers be checked at startup *
1852*************************************************/
1853
1854/* The tls_require_ciphers option, if set, must be something which the
1855library can parse.
1856
1857Returns: NULL on success, or error message
1858*/
1859
1860uschar *
1861tls_validate_require_cipher(void)
1862{
1863SSL_CTX *ctx;
1864uschar *s, *expciphers, *err;
1865
1866/* this duplicates from tls_init(), we need a better "init just global
1867state, for no specific purpose" singleton function of our own */
1868
1869SSL_load_error_strings();
1870OpenSSL_add_ssl_algorithms();
1871#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1872/* SHA256 is becoming ever more popular. This makes sure it gets added to the
1873list of available digests. */
1874EVP_add_digest(EVP_sha256());
1875#endif
1876
1877if (!(tls_require_ciphers && *tls_require_ciphers))
1878 return NULL;
1879
1880if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1881 return US"failed to expand tls_require_ciphers";
1882
1883if (!(expciphers && *expciphers))
1884 return NULL;
1885
1886/* normalisation ripped from above */
1887s = expciphers;
1888while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1889
1890err = NULL;
1891
1892ctx = SSL_CTX_new(SSLv23_server_method());
1893if (!ctx)
1894 {
1895 ERR_error_string(ERR_get_error(), ssl_errstring);
1896 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1897 }
1898
1899DEBUG(D_tls)
1900 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1901
1902if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1903 {
1904 ERR_error_string(ERR_get_error(), ssl_errstring);
1905 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1906 }
1907
1908SSL_CTX_free(ctx);
1909
1910return err;
1911}
1912
1913
1914
1915
1916/*************************************************
36f12725
NM
1917* Report the library versions. *
1918*************************************************/
1919
1920/* There have historically been some issues with binary compatibility in
1921OpenSSL libraries; if Exim (like many other applications) is built against
1922one version of OpenSSL but the run-time linker picks up another version,
1923it can result in serious failures, including crashing with a SIGSEGV. So
1924report the version found by the compiler and the run-time version.
1925
1926Arguments: a FILE* to print the results to
1927Returns: nothing
1928*/
1929
1930void
1931tls_version_report(FILE *f)
1932{
754a0503
PP
1933fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1934 " Runtime: %s\n",
1935 OPENSSL_VERSION_TEXT,
1936 SSLeay_version(SSLEAY_VERSION));
36f12725
NM
1937}
1938
9e3331ea
TK
1939
1940
1941
1942/*************************************************
17c76198 1943* Random number generation *
9e3331ea
TK
1944*************************************************/
1945
1946/* Pseudo-random number generation. The result is not expected to be
1947cryptographically strong but not so weak that someone will shoot themselves
1948in the foot using it as a nonce in input in some email header scheme or
1949whatever weirdness they'll twist this into. The result should handle fork()
1950and avoid repeating sequences. OpenSSL handles that for us.
1951
1952Arguments:
1953 max range maximum
1954Returns a random number in range [0, max-1]
1955*/
1956
1957int
17c76198 1958vaguely_random_number(int max)
9e3331ea
TK
1959{
1960unsigned int r;
1961int i, needed_len;
de6135a0
PP
1962static pid_t pidlast = 0;
1963pid_t pidnow;
9e3331ea
TK
1964uschar *p;
1965uschar smallbuf[sizeof(r)];
1966
1967if (max <= 1)
1968 return 0;
1969
de6135a0
PP
1970pidnow = getpid();
1971if (pidnow != pidlast)
1972 {
1973 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
1974 is unique for each thread", this doesn't apparently apply across processes,
1975 so our own warning from vaguely_random_number_fallback() applies here too.
1976 Fix per PostgreSQL. */
1977 if (pidlast != 0)
1978 RAND_cleanup();
1979 pidlast = pidnow;
1980 }
1981
9e3331ea
TK
1982/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1983if (!RAND_status())
1984 {
1985 randstuff r;
1986 gettimeofday(&r.tv, NULL);
1987 r.p = getpid();
1988
1989 RAND_seed((uschar *)(&r), sizeof(r));
1990 }
1991/* We're after pseudo-random, not random; if we still don't have enough data
1992in the internal PRNG then our options are limited. We could sleep and hope
1993for entropy to come along (prayer technique) but if the system is so depleted
1994in the first place then something is likely to just keep taking it. Instead,
1995we'll just take whatever little bit of pseudo-random we can still manage to
1996get. */
1997
1998needed_len = sizeof(r);
1999/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2000asked for a number less than 10. */
2001for (r = max, i = 0; r; ++i)
2002 r >>= 1;
2003i = (i + 7) / 8;
2004if (i < needed_len)
2005 needed_len = i;
2006
2007/* We do not care if crypto-strong */
17c76198
PP
2008i = RAND_pseudo_bytes(smallbuf, needed_len);
2009if (i < 0)
2010 {
2011 DEBUG(D_all)
2012 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2013 return vaguely_random_number_fallback(max);
2014 }
2015
9e3331ea
TK
2016r = 0;
2017for (p = smallbuf; needed_len; --needed_len, ++p)
2018 {
2019 r *= 256;
2020 r += *p;
2021 }
2022
2023/* We don't particularly care about weighted results; if someone wants
2024smooth distribution and cares enough then they should submit a patch then. */
2025return r % max;
2026}
2027
77bb000f
PP
2028
2029
2030
2031/*************************************************
2032* OpenSSL option parse *
2033*************************************************/
2034
2035/* Parse one option for tls_openssl_options_parse below
2036
2037Arguments:
2038 name one option name
2039 value place to store a value for it
2040Returns success or failure in parsing
2041*/
2042
2043struct exim_openssl_option {
2044 uschar *name;
2045 long value;
2046};
2047/* We could use a macro to expand, but we need the ifdef and not all the
2048options document which version they were introduced in. Policylet: include
2049all options unless explicitly for DTLS, let the administrator choose which
2050to apply.
2051
2052This list is current as of:
e2fbf4a2
PP
2053 ==> 1.0.1b <==
2054Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2055*/
77bb000f
PP
2056static struct exim_openssl_option exim_openssl_options[] = {
2057/* KEEP SORTED ALPHABETICALLY! */
2058#ifdef SSL_OP_ALL
73a46702 2059 { US"all", SSL_OP_ALL },
77bb000f
PP
2060#endif
2061#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2062 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2063#endif
2064#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2065 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2066#endif
2067#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2068 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2069#endif
2070#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2071 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2072#endif
2073#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2074 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2075#endif
2076#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2077 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2078#endif
2079#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2080 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2081#endif
2082#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2083 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2084#endif
2085#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2086 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2087#endif
2088#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2089 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2090#endif
c80c5570
PP
2091#ifdef SSL_OP_NO_COMPRESSION
2092 { US"no_compression", SSL_OP_NO_COMPRESSION },
2093#endif
77bb000f 2094#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2095 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2096#endif
c0c7b2da
PP
2097#ifdef SSL_OP_NO_SSLv2
2098 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2099#endif
2100#ifdef SSL_OP_NO_SSLv3
2101 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2102#endif
2103#ifdef SSL_OP_NO_TICKET
2104 { US"no_ticket", SSL_OP_NO_TICKET },
2105#endif
2106#ifdef SSL_OP_NO_TLSv1
2107 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2108#endif
c80c5570
PP
2109#ifdef SSL_OP_NO_TLSv1_1
2110#if SSL_OP_NO_TLSv1_1 == 0x00000400L
2111 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2112#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2113#else
2114 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2115#endif
2116#endif
2117#ifdef SSL_OP_NO_TLSv1_2
2118 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2119#endif
e2fbf4a2
PP
2120#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2121 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2122#endif
77bb000f 2123#ifdef SSL_OP_SINGLE_DH_USE
73a46702 2124 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
2125#endif
2126#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 2127 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
2128#endif
2129#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 2130 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
2131#endif
2132#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 2133 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
2134#endif
2135#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 2136 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
2137#endif
2138#ifdef SSL_OP_TLS_D5_BUG
73a46702 2139 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
2140#endif
2141#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 2142 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
2143#endif
2144};
2145static int exim_openssl_options_size =
2146 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2147
c80c5570 2148
77bb000f
PP
2149static BOOL
2150tls_openssl_one_option_parse(uschar *name, long *value)
2151{
2152int first = 0;
2153int last = exim_openssl_options_size;
2154while (last > first)
2155 {
2156 int middle = (first + last)/2;
2157 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2158 if (c == 0)
2159 {
2160 *value = exim_openssl_options[middle].value;
2161 return TRUE;
2162 }
2163 else if (c > 0)
2164 first = middle + 1;
2165 else
2166 last = middle;
2167 }
2168return FALSE;
2169}
2170
2171
2172
2173
2174/*************************************************
2175* OpenSSL option parsing logic *
2176*************************************************/
2177
2178/* OpenSSL has a number of compatibility options which an administrator might
2179reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2180we look like log_selector.
2181
2182Arguments:
2183 option_spec the administrator-supplied string of options
2184 results ptr to long storage for the options bitmap
2185Returns success or failure
2186*/
2187
2188BOOL
2189tls_openssl_options_parse(uschar *option_spec, long *results)
2190{
2191long result, item;
2192uschar *s, *end;
2193uschar keep_c;
2194BOOL adding, item_parsed;
2195
0e944a0d 2196result = 0L;
b1770b6e 2197/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 2198 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
2199#ifdef SSL_OP_NO_SSLv2
2200result |= SSL_OP_NO_SSLv2;
2201#endif
77bb000f
PP
2202
2203if (option_spec == NULL)
2204 {
2205 *results = result;
2206 return TRUE;
2207 }
2208
2209for (s=option_spec; *s != '\0'; /**/)
2210 {
2211 while (isspace(*s)) ++s;
2212 if (*s == '\0')
2213 break;
2214 if (*s != '+' && *s != '-')
2215 {
2216 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 2217 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
2218 return FALSE;
2219 }
2220 adding = *s++ == '+';
2221 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2222 keep_c = *end;
2223 *end = '\0';
2224 item_parsed = tls_openssl_one_option_parse(s, &item);
2225 if (!item_parsed)
2226 {
0e944a0d 2227 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
2228 return FALSE;
2229 }
2230 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2231 adding ? "adding" : "removing", result, item, s);
2232 if (adding)
2233 result |= item;
2234 else
2235 result &= ~item;
2236 *end = keep_c;
2237 s = end;
2238 }
2239
2240*results = result;
2241return TRUE;
2242}
2243
059ec3d9 2244/* End of tls-openssl.c */