Support safari_ecdhe_ecdsa_bug for openssl_options
[exim.git] / src / src / tls-openssl.c
CommitLineData
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
c4ceed07 5/* Copyright (c) University of Cambridge 1995 - 2012 */
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6/* See the file NOTICE for conditions of use and distribution. */
7
f5d78688
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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>
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
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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;
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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;
059ec3d9
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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
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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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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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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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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
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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;
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",
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JH
304 *calledp ? "" : " authenticated", txt);
305 tlsp->peerdn = txt;
059ec3d9
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306 }
307
f5d78688
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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*/
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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
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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
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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;
059ec3d9 1140uschar *ver;
059ec3d9
PH
1141
1142switch (ssl->session->ssl_version)
1143 {
1144 case SSL2_VERSION:
1145 ver = US"SSLv2";
1146 break;
1147
1148 case SSL3_VERSION:
1149 ver = US"SSLv3";
1150 break;
1151
1152 case TLS1_VERSION:
1153 ver = US"TLSv1";
1154 break;
1155
c80c5570
PP
1156#ifdef TLS1_1_VERSION
1157 case TLS1_1_VERSION:
1158 ver = US"TLSv1.1";
1159 break;
1160#endif
1161
1162#ifdef TLS1_2_VERSION
1163 case TLS1_2_VERSION:
1164 ver = US"TLSv1.2";
1165 break;
1166#endif
1167
059ec3d9
PH
1168 default:
1169 ver = US"UNKNOWN";
1170 }
1171
57b3a7f5 1172c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1173SSL_CIPHER_get_bits(c, bits);
059ec3d9 1174
817d9f57
JH
1175string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1176 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1177
1178DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1179}
1180
1181
1182
1183
1184
1185/*************************************************
1186* Set up for verifying certificates *
1187*************************************************/
1188
1189/* Called by both client and server startup
1190
1191Arguments:
7be682ca 1192 sctx SSL_CTX* to initialise
059ec3d9
PH
1193 certs certs file or NULL
1194 crl CRL file or NULL
1195 host NULL in a server; the remote host in a client
1196 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1197 otherwise passed as FALSE
983207c1 1198 cert_vfy_cb Callback function for certificate verification
059ec3d9
PH
1199
1200Returns: OK/DEFER/FAIL
1201*/
1202
1203static int
983207c1
JH
1204setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1205 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
059ec3d9
PH
1206{
1207uschar *expcerts, *expcrl;
1208
1209if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1210 return DEFER;
1211
26e72755 1212if (expcerts != NULL && *expcerts != '\0')
059ec3d9
PH
1213 {
1214 struct stat statbuf;
7be682ca 1215 if (!SSL_CTX_set_default_verify_paths(sctx))
7199e1ee 1216 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
059ec3d9
PH
1217
1218 if (Ustat(expcerts, &statbuf) < 0)
1219 {
1220 log_write(0, LOG_MAIN|LOG_PANIC,
1221 "failed to stat %s for certificates", expcerts);
1222 return DEFER;
1223 }
1224 else
1225 {
1226 uschar *file, *dir;
1227 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1228 { file = NULL; dir = expcerts; }
1229 else
1230 { file = expcerts; dir = NULL; }
1231
1232 /* If a certificate file is empty, the next function fails with an
1233 unhelpful error message. If we skip it, we get the correct behaviour (no
1234 certificates are recognized, but the error message is still misleading (it
1235 says no certificate was supplied.) But this is better. */
1236
1237 if ((file == NULL || statbuf.st_size > 0) &&
7be682ca 1238 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
7199e1ee 1239 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
059ec3d9
PH
1240
1241 if (file != NULL)
1242 {
7be682ca 1243 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
059ec3d9
PH
1244 }
1245 }
1246
1247 /* Handle a certificate revocation list. */
1248
1249 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1250
8b417f2c
PH
1251 /* This bit of code is now the version supplied by Lars Mainka. (I have
1252 * merely reformatted it into the Exim code style.)
1253
1254 * "From here I changed the code to add support for multiple crl's
1255 * in pem format in one file or to support hashed directory entries in
1256 * pem format instead of a file. This method now uses the library function
1257 * X509_STORE_load_locations to add the CRL location to the SSL context.
1258 * OpenSSL will then handle the verify against CA certs and CRLs by
1259 * itself in the verify callback." */
1260
059ec3d9
PH
1261 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1262 if (expcrl != NULL && *expcrl != 0)
1263 {
8b417f2c
PH
1264 struct stat statbufcrl;
1265 if (Ustat(expcrl, &statbufcrl) < 0)
1266 {
1267 log_write(0, LOG_MAIN|LOG_PANIC,
1268 "failed to stat %s for certificates revocation lists", expcrl);
1269 return DEFER;
1270 }
1271 else
059ec3d9 1272 {
8b417f2c
PH
1273 /* is it a file or directory? */
1274 uschar *file, *dir;
7be682ca 1275 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1276 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1277 {
8b417f2c
PH
1278 file = NULL;
1279 dir = expcrl;
1280 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1281 }
1282 else
1283 {
8b417f2c
PH
1284 file = expcrl;
1285 dir = NULL;
1286 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1287 }
8b417f2c 1288 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
7199e1ee 1289 return tls_error(US"X509_STORE_load_locations", host, NULL);
8b417f2c
PH
1290
1291 /* setting the flags to check against the complete crl chain */
1292
1293 X509_STORE_set_flags(cvstore,
1294 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1295 }
059ec3d9
PH
1296 }
1297
1298 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1299
1300 /* If verification is optional, don't fail if no certificate */
1301
7be682ca 1302 SSL_CTX_set_verify(sctx,
059ec3d9 1303 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1304 cert_vfy_cb);
059ec3d9
PH
1305 }
1306
1307return OK;
1308}
1309
1310
1311
1312/*************************************************
1313* Start a TLS session in a server *
1314*************************************************/
1315
1316/* This is called when Exim is running as a server, after having received
1317the STARTTLS command. It must respond to that command, and then negotiate
1318a TLS session.
1319
1320Arguments:
1321 require_ciphers allowed ciphers
1322
1323Returns: OK on success
1324 DEFER for errors before the start of the negotiation
1325 FAIL for errors during the negotation; the server can't
1326 continue running.
1327*/
1328
1329int
17c76198 1330tls_server_start(const uschar *require_ciphers)
059ec3d9
PH
1331{
1332int rc;
1333uschar *expciphers;
7be682ca 1334tls_ext_ctx_cb *cbinfo;
817d9f57 1335static uschar cipherbuf[256];
059ec3d9
PH
1336
1337/* Check for previous activation */
1338
817d9f57 1339if (tls_in.active >= 0)
059ec3d9 1340 {
5ca6d115 1341 tls_error(US"STARTTLS received after TLS started", NULL, US"");
059ec3d9
PH
1342 smtp_printf("554 Already in TLS\r\n");
1343 return FAIL;
1344 }
1345
1346/* Initialize the SSL library. If it fails, it will already have logged
1347the error. */
1348
817d9f57 1349rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
3f7eeb86
PP
1350#ifdef EXPERIMENTAL_OCSP
1351 tls_ocsp_file,
1352#endif
817d9f57 1353 NULL, &server_static_cbinfo);
059ec3d9 1354if (rc != OK) return rc;
817d9f57 1355cbinfo = server_static_cbinfo;
059ec3d9
PH
1356
1357if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1358 return FAIL;
1359
1360/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1361were historically separated by underscores. So that I can use either form in my
1362tests, and also for general convenience, we turn underscores into hyphens here.
1363*/
059ec3d9
PH
1364
1365if (expciphers != NULL)
1366 {
1367 uschar *s = expciphers;
1368 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1369 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1370 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
7199e1ee 1371 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
7be682ca 1372 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1373 }
1374
1375/* If this is a host for which certificate verification is mandatory or
1376optional, set up appropriately. */
1377
817d9f57 1378tls_in.certificate_verified = FALSE;
a2ff477a 1379server_verify_callback_called = FALSE;
059ec3d9
PH
1380
1381if (verify_check_host(&tls_verify_hosts) == OK)
1382 {
983207c1
JH
1383 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1384 FALSE, verify_callback_server);
059ec3d9 1385 if (rc != OK) return rc;
a2ff477a 1386 server_verify_optional = FALSE;
059ec3d9
PH
1387 }
1388else if (verify_check_host(&tls_try_verify_hosts) == OK)
1389 {
983207c1
JH
1390 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1391 TRUE, verify_callback_server);
059ec3d9 1392 if (rc != OK) return rc;
a2ff477a 1393 server_verify_optional = TRUE;
059ec3d9
PH
1394 }
1395
1396/* Prepare for new connection */
1397
817d9f57 1398if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
da3ad30d
PP
1399
1400/* Warning: we used to SSL_clear(ssl) here, it was removed.
1401 *
1402 * With the SSL_clear(), we get strange interoperability bugs with
1403 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1404 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1405 *
1406 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1407 * session shutdown. In this case, we have a brand new object and there's no
1408 * obvious reason to immediately clear it. I'm guessing that this was
1409 * originally added because of incomplete initialisation which the clear fixed,
1410 * in some historic release.
1411 */
059ec3d9
PH
1412
1413/* Set context and tell client to go ahead, except in the case of TLS startup
1414on connection, where outputting anything now upsets the clients and tends to
1415make them disconnect. We need to have an explicit fflush() here, to force out
1416the response. Other smtp_printf() calls do not need it, because in non-TLS
1417mode, the fflush() happens when smtp_getc() is called. */
1418
817d9f57
JH
1419SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1420if (!tls_in.on_connect)
059ec3d9
PH
1421 {
1422 smtp_printf("220 TLS go ahead\r\n");
1423 fflush(smtp_out);
1424 }
1425
1426/* Now negotiate the TLS session. We put our own timer on it, since it seems
1427that the OpenSSL library doesn't. */
1428
817d9f57
JH
1429SSL_set_wfd(server_ssl, fileno(smtp_out));
1430SSL_set_rfd(server_ssl, fileno(smtp_in));
1431SSL_set_accept_state(server_ssl);
059ec3d9
PH
1432
1433DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1434
1435sigalrm_seen = FALSE;
1436if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 1437rc = SSL_accept(server_ssl);
059ec3d9
PH
1438alarm(0);
1439
1440if (rc <= 0)
1441 {
7199e1ee 1442 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
77bb000f
PP
1443 if (ERR_get_error() == 0)
1444 log_write(0, LOG_MAIN,
a053d125 1445 "TLS client disconnected cleanly (rejected our certificate?)");
059ec3d9
PH
1446 return FAIL;
1447 }
1448
1449DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1450
1451/* TLS has been set up. Adjust the input functions to read via TLS,
1452and initialize things. */
1453
817d9f57
JH
1454construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1455tls_in.cipher = cipherbuf;
059ec3d9
PH
1456
1457DEBUG(D_tls)
1458 {
1459 uschar buf[2048];
817d9f57 1460 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
1461 debug_printf("Shared ciphers: %s\n", buf);
1462 }
1463
1464
817d9f57
JH
1465/* Only used by the server-side tls (tls_in), including tls_getc.
1466 Client-side (tls_out) reads (seem to?) go via
1467 smtp_read_response()/ip_recv().
1468 Hence no need to duplicate for _in and _out.
1469 */
059ec3d9
PH
1470ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1471ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1472ssl_xfer_eof = ssl_xfer_error = 0;
1473
1474receive_getc = tls_getc;
1475receive_ungetc = tls_ungetc;
1476receive_feof = tls_feof;
1477receive_ferror = tls_ferror;
58eb016e 1478receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 1479
817d9f57 1480tls_in.active = fileno(smtp_out);
059ec3d9
PH
1481return OK;
1482}
1483
1484
1485
1486
1487
1488/*************************************************
1489* Start a TLS session in a client *
1490*************************************************/
1491
1492/* Called from the smtp transport after STARTTLS has been accepted.
1493
1494Argument:
1495 fd the fd of the connection
1496 host connected host (for messages)
83da1223 1497 addr the first address
059ec3d9
PH
1498 certificate certificate file
1499 privatekey private key file
3f0945ff 1500 sni TLS SNI to send to remote host
059ec3d9
PH
1501 verify_certs file for certificate verify
1502 crl file containing CRL
1503 require_ciphers list of allowed ciphers
54c90be1
PP
1504 dh_min_bits minimum number of bits acceptable in server's DH prime
1505 (unused in OpenSSL)
83da1223 1506 timeout startup timeout
059ec3d9
PH
1507
1508Returns: OK on success
1509 FAIL otherwise - note that tls_error() will not give DEFER
1510 because this is not a server
1511*/
1512
1513int
f5d78688 1514tls_client_start(int fd, host_item *host, address_item *addr,
3f0945ff
PP
1515 uschar *certificate, uschar *privatekey, uschar *sni,
1516 uschar *verify_certs, uschar *crl,
f5d78688
JH
1517 uschar *require_ciphers,
1518#ifdef EXPERIMENTAL_OCSP
1519 uschar *hosts_require_ocsp,
1520#endif
1521 int dh_min_bits ARG_UNUSED, int timeout)
059ec3d9
PH
1522{
1523static uschar txt[256];
1524uschar *expciphers;
1525X509* server_cert;
1526int rc;
817d9f57 1527static uschar cipherbuf[256];
f5d78688
JH
1528#ifdef EXPERIMENTAL_OCSP
1529BOOL require_ocsp = verify_check_this_host(&hosts_require_ocsp,
1530 NULL, host->name, host->address, NULL) == OK;
1531#endif
059ec3d9 1532
f5d78688 1533rc = tls_init(&client_ctx, host, NULL, certificate, privatekey,
3f7eeb86 1534#ifdef EXPERIMENTAL_OCSP
f5d78688 1535 require_ocsp ? US"" : NULL,
3f7eeb86 1536#endif
817d9f57 1537 addr, &client_static_cbinfo);
059ec3d9
PH
1538if (rc != OK) return rc;
1539
817d9f57 1540tls_out.certificate_verified = FALSE;
a2ff477a 1541client_verify_callback_called = FALSE;
059ec3d9
PH
1542
1543if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1544 return FAIL;
1545
1546/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1547are separated by underscores. So that I can use either form in my tests, and
1548also for general convenience, we turn underscores into hyphens here. */
1549
1550if (expciphers != NULL)
1551 {
1552 uschar *s = expciphers;
1553 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1554 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1555 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
7199e1ee 1556 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
059ec3d9
PH
1557 }
1558
983207c1 1559rc = setup_certs(client_ctx, verify_certs, crl, host, FALSE, verify_callback_client);
059ec3d9
PH
1560if (rc != OK) return rc;
1561
817d9f57
JH
1562if ((client_ssl = SSL_new(client_ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1563SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1564SSL_set_fd(client_ssl, fd);
1565SSL_set_connect_state(client_ssl);
059ec3d9 1566
3f0945ff
PP
1567if (sni)
1568 {
817d9f57 1569 if (!expand_check(sni, US"tls_sni", &tls_out.sni))
3f0945ff 1570 return FAIL;
ec4b68e5 1571 if (tls_out.sni == NULL)
2c9a0e86
PP
1572 {
1573 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1574 }
ec4b68e5 1575 else if (!Ustrlen(tls_out.sni))
817d9f57 1576 tls_out.sni = NULL;
3f0945ff
PP
1577 else
1578 {
35731706 1579#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
1580 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1581 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706
PP
1582#else
1583 DEBUG(D_tls)
1584 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
02d9264f 1585 tls_out.sni);
35731706 1586#endif
3f0945ff
PP
1587 }
1588 }
1589
f5d78688
JH
1590#ifdef EXPERIMENTAL_OCSP
1591/* Request certificate status at connection-time. If the server
1592does OCSP stapling we will get the callback (set in tls_init()) */
1593if (require_ocsp)
1594 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1595#endif
1596
059ec3d9
PH
1597/* There doesn't seem to be a built-in timeout on connection. */
1598
1599DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1600sigalrm_seen = FALSE;
1601alarm(timeout);
817d9f57 1602rc = SSL_connect(client_ssl);
059ec3d9
PH
1603alarm(0);
1604
1605if (rc <= 0)
7199e1ee 1606 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
059ec3d9
PH
1607
1608DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1609
453a6645 1610/* Beware anonymous ciphers which lead to server_cert being NULL */
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));
817d9f57 1616 tls_out.peerdn = txt;
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
817d9f57 1624tls_out.active = fd;
059ec3d9
PH
1625return OK;
1626}
1627
1628
1629
1630
1631
1632/*************************************************
1633* TLS version of getc *
1634*************************************************/
1635
1636/* This gets the next byte from the TLS input buffer. If the buffer is empty,
1637it refills the buffer via the SSL reading function.
1638
1639Arguments: none
1640Returns: the next character or EOF
817d9f57
JH
1641
1642Only used by the server-side TLS.
059ec3d9
PH
1643*/
1644
1645int
1646tls_getc(void)
1647{
1648if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1649 {
1650 int error;
1651 int inbytes;
1652
817d9f57 1653 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
c80c5570 1654 ssl_xfer_buffer, ssl_xfer_buffer_size);
059ec3d9
PH
1655
1656 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57
JH
1657 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1658 error = SSL_get_error(server_ssl, inbytes);
059ec3d9
PH
1659 alarm(0);
1660
1661 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1662 closed down, not that the socket itself has been closed down. Revert to
1663 non-SSL handling. */
1664
1665 if (error == SSL_ERROR_ZERO_RETURN)
1666 {
1667 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1668
1669 receive_getc = smtp_getc;
1670 receive_ungetc = smtp_ungetc;
1671 receive_feof = smtp_feof;
1672 receive_ferror = smtp_ferror;
58eb016e 1673 receive_smtp_buffered = smtp_buffered;
059ec3d9 1674
817d9f57
JH
1675 SSL_free(server_ssl);
1676 server_ssl = NULL;
1677 tls_in.active = -1;
1678 tls_in.bits = 0;
1679 tls_in.cipher = NULL;
1680 tls_in.peerdn = NULL;
1681 tls_in.sni = NULL;
059ec3d9
PH
1682
1683 return smtp_getc();
1684 }
1685
1686 /* Handle genuine errors */
1687
ba084640
PP
1688 else if (error == SSL_ERROR_SSL)
1689 {
1690 ERR_error_string(ERR_get_error(), ssl_errstring);
89dd51cd 1691 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
ba084640
PP
1692 ssl_xfer_error = 1;
1693 return EOF;
1694 }
1695
059ec3d9
PH
1696 else if (error != SSL_ERROR_NONE)
1697 {
1698 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1699 ssl_xfer_error = 1;
1700 return EOF;
1701 }
c80c5570 1702
80a47a2c
TK
1703#ifndef DISABLE_DKIM
1704 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1705#endif
059ec3d9
PH
1706 ssl_xfer_buffer_hwm = inbytes;
1707 ssl_xfer_buffer_lwm = 0;
1708 }
1709
1710/* Something in the buffer; return next uschar */
1711
1712return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1713}
1714
1715
1716
1717/*************************************************
1718* Read bytes from TLS channel *
1719*************************************************/
1720
1721/*
1722Arguments:
1723 buff buffer of data
1724 len size of buffer
1725
1726Returns: the number of bytes read
1727 -1 after a failed read
817d9f57
JH
1728
1729Only used by the client-side TLS.
059ec3d9
PH
1730*/
1731
1732int
389ca47a 1733tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 1734{
389ca47a 1735SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
1736int inbytes;
1737int error;
1738
389ca47a 1739DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 1740 buff, (unsigned int)len);
059ec3d9 1741
389ca47a
JH
1742inbytes = SSL_read(ssl, CS buff, len);
1743error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
1744
1745if (error == SSL_ERROR_ZERO_RETURN)
1746 {
1747 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1748 return -1;
1749 }
1750else if (error != SSL_ERROR_NONE)
1751 {
1752 return -1;
1753 }
1754
1755return inbytes;
1756}
1757
1758
1759
1760
1761
1762/*************************************************
1763* Write bytes down TLS channel *
1764*************************************************/
1765
1766/*
1767Arguments:
817d9f57 1768 is_server channel specifier
059ec3d9
PH
1769 buff buffer of data
1770 len number of bytes
1771
1772Returns: the number of bytes after a successful write,
1773 -1 after a failed write
817d9f57
JH
1774
1775Used by both server-side and client-side TLS.
059ec3d9
PH
1776*/
1777
1778int
817d9f57 1779tls_write(BOOL is_server, const uschar *buff, size_t len)
059ec3d9
PH
1780{
1781int outbytes;
1782int error;
1783int left = len;
817d9f57 1784SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9 1785
c80c5570 1786DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
059ec3d9
PH
1787while (left > 0)
1788 {
c80c5570 1789 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
1790 outbytes = SSL_write(ssl, CS buff, left);
1791 error = SSL_get_error(ssl, outbytes);
1792 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1793 switch (error)
1794 {
1795 case SSL_ERROR_SSL:
1796 ERR_error_string(ERR_get_error(), ssl_errstring);
1797 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1798 return -1;
1799
1800 case SSL_ERROR_NONE:
1801 left -= outbytes;
1802 buff += outbytes;
1803 break;
1804
1805 case SSL_ERROR_ZERO_RETURN:
1806 log_write(0, LOG_MAIN, "SSL channel closed on write");
1807 return -1;
1808
817d9f57
JH
1809 case SSL_ERROR_SYSCALL:
1810 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
1811 sender_fullhost ? sender_fullhost : US"<unknown>",
1812 strerror(errno));
1813
059ec3d9
PH
1814 default:
1815 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1816 return -1;
1817 }
1818 }
1819return len;
1820}
1821
1822
1823
1824/*************************************************
1825* Close down a TLS session *
1826*************************************************/
1827
1828/* This is also called from within a delivery subprocess forked from the
1829daemon, to shut down the TLS library, without actually doing a shutdown (which
1830would tamper with the SSL session in the parent process).
1831
1832Arguments: TRUE if SSL_shutdown is to be called
1833Returns: nothing
817d9f57
JH
1834
1835Used by both server-side and client-side TLS.
059ec3d9
PH
1836*/
1837
1838void
817d9f57 1839tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 1840{
817d9f57 1841SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 1842int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
1843
1844if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
1845
1846if (shutdown)
1847 {
1848 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 1849 SSL_shutdown(*sslp);
059ec3d9
PH
1850 }
1851
817d9f57
JH
1852SSL_free(*sslp);
1853*sslp = NULL;
059ec3d9 1854
817d9f57 1855*fdp = -1;
059ec3d9
PH
1856}
1857
36f12725
NM
1858
1859
1860
1861/*************************************************
3375e053
PP
1862* Let tls_require_ciphers be checked at startup *
1863*************************************************/
1864
1865/* The tls_require_ciphers option, if set, must be something which the
1866library can parse.
1867
1868Returns: NULL on success, or error message
1869*/
1870
1871uschar *
1872tls_validate_require_cipher(void)
1873{
1874SSL_CTX *ctx;
1875uschar *s, *expciphers, *err;
1876
1877/* this duplicates from tls_init(), we need a better "init just global
1878state, for no specific purpose" singleton function of our own */
1879
1880SSL_load_error_strings();
1881OpenSSL_add_ssl_algorithms();
1882#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1883/* SHA256 is becoming ever more popular. This makes sure it gets added to the
1884list of available digests. */
1885EVP_add_digest(EVP_sha256());
1886#endif
1887
1888if (!(tls_require_ciphers && *tls_require_ciphers))
1889 return NULL;
1890
1891if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1892 return US"failed to expand tls_require_ciphers";
1893
1894if (!(expciphers && *expciphers))
1895 return NULL;
1896
1897/* normalisation ripped from above */
1898s = expciphers;
1899while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1900
1901err = NULL;
1902
1903ctx = SSL_CTX_new(SSLv23_server_method());
1904if (!ctx)
1905 {
1906 ERR_error_string(ERR_get_error(), ssl_errstring);
1907 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1908 }
1909
1910DEBUG(D_tls)
1911 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1912
1913if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1914 {
1915 ERR_error_string(ERR_get_error(), ssl_errstring);
1916 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1917 }
1918
1919SSL_CTX_free(ctx);
1920
1921return err;
1922}
1923
1924
1925
1926
1927/*************************************************
36f12725
NM
1928* Report the library versions. *
1929*************************************************/
1930
1931/* There have historically been some issues with binary compatibility in
1932OpenSSL libraries; if Exim (like many other applications) is built against
1933one version of OpenSSL but the run-time linker picks up another version,
1934it can result in serious failures, including crashing with a SIGSEGV. So
1935report the version found by the compiler and the run-time version.
1936
1937Arguments: a FILE* to print the results to
1938Returns: nothing
1939*/
1940
1941void
1942tls_version_report(FILE *f)
1943{
754a0503
PP
1944fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1945 " Runtime: %s\n",
1946 OPENSSL_VERSION_TEXT,
1947 SSLeay_version(SSLEAY_VERSION));
36f12725
NM
1948}
1949
9e3331ea
TK
1950
1951
1952
1953/*************************************************
17c76198 1954* Random number generation *
9e3331ea
TK
1955*************************************************/
1956
1957/* Pseudo-random number generation. The result is not expected to be
1958cryptographically strong but not so weak that someone will shoot themselves
1959in the foot using it as a nonce in input in some email header scheme or
1960whatever weirdness they'll twist this into. The result should handle fork()
1961and avoid repeating sequences. OpenSSL handles that for us.
1962
1963Arguments:
1964 max range maximum
1965Returns a random number in range [0, max-1]
1966*/
1967
1968int
17c76198 1969vaguely_random_number(int max)
9e3331ea
TK
1970{
1971unsigned int r;
1972int i, needed_len;
de6135a0
PP
1973static pid_t pidlast = 0;
1974pid_t pidnow;
9e3331ea
TK
1975uschar *p;
1976uschar smallbuf[sizeof(r)];
1977
1978if (max <= 1)
1979 return 0;
1980
de6135a0
PP
1981pidnow = getpid();
1982if (pidnow != pidlast)
1983 {
1984 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
1985 is unique for each thread", this doesn't apparently apply across processes,
1986 so our own warning from vaguely_random_number_fallback() applies here too.
1987 Fix per PostgreSQL. */
1988 if (pidlast != 0)
1989 RAND_cleanup();
1990 pidlast = pidnow;
1991 }
1992
9e3331ea
TK
1993/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1994if (!RAND_status())
1995 {
1996 randstuff r;
1997 gettimeofday(&r.tv, NULL);
1998 r.p = getpid();
1999
2000 RAND_seed((uschar *)(&r), sizeof(r));
2001 }
2002/* We're after pseudo-random, not random; if we still don't have enough data
2003in the internal PRNG then our options are limited. We could sleep and hope
2004for entropy to come along (prayer technique) but if the system is so depleted
2005in the first place then something is likely to just keep taking it. Instead,
2006we'll just take whatever little bit of pseudo-random we can still manage to
2007get. */
2008
2009needed_len = sizeof(r);
2010/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2011asked for a number less than 10. */
2012for (r = max, i = 0; r; ++i)
2013 r >>= 1;
2014i = (i + 7) / 8;
2015if (i < needed_len)
2016 needed_len = i;
2017
2018/* We do not care if crypto-strong */
17c76198
PP
2019i = RAND_pseudo_bytes(smallbuf, needed_len);
2020if (i < 0)
2021 {
2022 DEBUG(D_all)
2023 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2024 return vaguely_random_number_fallback(max);
2025 }
2026
9e3331ea
TK
2027r = 0;
2028for (p = smallbuf; needed_len; --needed_len, ++p)
2029 {
2030 r *= 256;
2031 r += *p;
2032 }
2033
2034/* We don't particularly care about weighted results; if someone wants
2035smooth distribution and cares enough then they should submit a patch then. */
2036return r % max;
2037}
2038
77bb000f
PP
2039
2040
2041
2042/*************************************************
2043* OpenSSL option parse *
2044*************************************************/
2045
2046/* Parse one option for tls_openssl_options_parse below
2047
2048Arguments:
2049 name one option name
2050 value place to store a value for it
2051Returns success or failure in parsing
2052*/
2053
2054struct exim_openssl_option {
2055 uschar *name;
2056 long value;
2057};
2058/* We could use a macro to expand, but we need the ifdef and not all the
2059options document which version they were introduced in. Policylet: include
2060all options unless explicitly for DTLS, let the administrator choose which
2061to apply.
2062
2063This list is current as of:
e2fbf4a2
PP
2064 ==> 1.0.1b <==
2065Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2066*/
77bb000f
PP
2067static struct exim_openssl_option exim_openssl_options[] = {
2068/* KEEP SORTED ALPHABETICALLY! */
2069#ifdef SSL_OP_ALL
73a46702 2070 { US"all", SSL_OP_ALL },
77bb000f
PP
2071#endif
2072#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2073 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2074#endif
2075#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2076 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2077#endif
2078#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2079 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2080#endif
2081#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2082 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2083#endif
2084#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2085 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2086#endif
2087#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2088 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2089#endif
2090#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2091 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2092#endif
2093#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2094 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2095#endif
2096#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2097 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2098#endif
2099#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2100 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2101#endif
c80c5570
PP
2102#ifdef SSL_OP_NO_COMPRESSION
2103 { US"no_compression", SSL_OP_NO_COMPRESSION },
2104#endif
77bb000f 2105#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2106 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2107#endif
c0c7b2da
PP
2108#ifdef SSL_OP_NO_SSLv2
2109 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2110#endif
2111#ifdef SSL_OP_NO_SSLv3
2112 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2113#endif
2114#ifdef SSL_OP_NO_TICKET
2115 { US"no_ticket", SSL_OP_NO_TICKET },
2116#endif
2117#ifdef SSL_OP_NO_TLSv1
2118 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2119#endif
c80c5570
PP
2120#ifdef SSL_OP_NO_TLSv1_1
2121#if SSL_OP_NO_TLSv1_1 == 0x00000400L
2122 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2123#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2124#else
2125 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2126#endif
2127#endif
2128#ifdef SSL_OP_NO_TLSv1_2
2129 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2130#endif
e2fbf4a2
PP
2131#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2132 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2133#endif
77bb000f 2134#ifdef SSL_OP_SINGLE_DH_USE
73a46702 2135 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
2136#endif
2137#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 2138 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
2139#endif
2140#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 2141 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
2142#endif
2143#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 2144 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
2145#endif
2146#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 2147 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
2148#endif
2149#ifdef SSL_OP_TLS_D5_BUG
73a46702 2150 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
2151#endif
2152#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 2153 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
2154#endif
2155};
2156static int exim_openssl_options_size =
2157 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2158
c80c5570 2159
77bb000f
PP
2160static BOOL
2161tls_openssl_one_option_parse(uschar *name, long *value)
2162{
2163int first = 0;
2164int last = exim_openssl_options_size;
2165while (last > first)
2166 {
2167 int middle = (first + last)/2;
2168 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2169 if (c == 0)
2170 {
2171 *value = exim_openssl_options[middle].value;
2172 return TRUE;
2173 }
2174 else if (c > 0)
2175 first = middle + 1;
2176 else
2177 last = middle;
2178 }
2179return FALSE;
2180}
2181
2182
2183
2184
2185/*************************************************
2186* OpenSSL option parsing logic *
2187*************************************************/
2188
2189/* OpenSSL has a number of compatibility options which an administrator might
2190reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2191we look like log_selector.
2192
2193Arguments:
2194 option_spec the administrator-supplied string of options
2195 results ptr to long storage for the options bitmap
2196Returns success or failure
2197*/
2198
2199BOOL
2200tls_openssl_options_parse(uschar *option_spec, long *results)
2201{
2202long result, item;
2203uschar *s, *end;
2204uschar keep_c;
2205BOOL adding, item_parsed;
2206
0e944a0d 2207result = 0L;
b1770b6e 2208/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 2209 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
2210#ifdef SSL_OP_NO_SSLv2
2211result |= SSL_OP_NO_SSLv2;
2212#endif
77bb000f
PP
2213
2214if (option_spec == NULL)
2215 {
2216 *results = result;
2217 return TRUE;
2218 }
2219
2220for (s=option_spec; *s != '\0'; /**/)
2221 {
2222 while (isspace(*s)) ++s;
2223 if (*s == '\0')
2224 break;
2225 if (*s != '+' && *s != '-')
2226 {
2227 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 2228 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
2229 return FALSE;
2230 }
2231 adding = *s++ == '+';
2232 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2233 keep_c = *end;
2234 *end = '\0';
2235 item_parsed = tls_openssl_one_option_parse(s, &item);
2236 if (!item_parsed)
2237 {
0e944a0d 2238 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
2239 return FALSE;
2240 }
2241 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2242 adding ? "adding" : "removing", result, item, s);
2243 if (adding)
2244 result |= item;
2245 else
2246 result &= ~item;
2247 *end = keep_c;
2248 s = end;
2249 }
2250
2251*results = result;
2252return TRUE;
2253}
2254
059ec3d9 2255/* End of tls-openssl.c */