c90ae1411caaa64234f826ace24af37f1e7b650f
[exim.git] / src / src / tls-gnu.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Copyright (c) Phil Pennock 2012 */
9
10 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
11 one of the available supported implementations. This file is #included into
12 tls.c when USE_GNUTLS has been set.
13
14 The code herein is a revamp of GnuTLS integration using the current APIs; the
15 original tls-gnu.c was based on a patch which was contributed by Nikos
16 Mavroyanopoulos. The revamp is partially a rewrite, partially cut&paste as
17 appropriate.
18
19 APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
20 which is not widely deployed by OS vendors. Will note issues below, which may
21 assist in updating the code in the future. Another sources of hints is
22 mod_gnutls for Apache (SNI callback registration and handling).
23
24 Keeping client and server variables more split than before and is currently
25 the norm, in anticipation of TLS in ACL callouts.
26
27 I wanted to switch to gnutls_certificate_set_verify_function() so that
28 certificate rejection could happen during handshake where it belongs, rather
29 than being dropped afterwards, but that was introduced in 2.10.0 and Debian
30 (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
31
32 (I wasn't looking for libraries quite that old, when updating to get rid of
33 compiler warnings of deprecated APIs. If it turns out that a lot of the rest
34 require current GnuTLS, then we'll drop support for the ancient libraries).
35 */
36
37 #include <gnutls/gnutls.h>
38 /* needed for cert checks in verification and DN extraction: */
39 #include <gnutls/x509.h>
40 /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
41 #include <gnutls/crypto.h>
42 /* needed to disable PKCS11 autoload unless requested */
43 #if GNUTLS_VERSION_NUMBER >= 0x020c00
44 # include <gnutls/pkcs11.h>
45 #endif
46
47 /* GnuTLS 2 vs 3
48
49 GnuTLS 3 only:
50 gnutls_global_set_audit_log_function()
51
52 Changes:
53 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
54 */
55
56 /* Local static variables for GnuTLS */
57
58 /* Values for verify_requirement */
59
60 enum peer_verify_requirement { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
61
62 /* This holds most state for server or client; with this, we can set up an
63 outbound TLS-enabled connection in an ACL callout, while not stomping all
64 over the TLS variables available for expansion.
65
66 Some of these correspond to variables in globals.c; those variables will
67 be set to point to content in one of these instances, as appropriate for
68 the stage of the process lifetime.
69
70 Not handled here: global tls_channelbinding_b64.
71 */
72
73 typedef struct exim_gnutls_state {
74 gnutls_session_t session;
75 gnutls_certificate_credentials_t x509_cred;
76 gnutls_priority_t priority_cache;
77 enum peer_verify_requirement verify_requirement;
78 int fd_in;
79 int fd_out;
80 BOOL peer_cert_verified;
81 BOOL trigger_sni_changes;
82 BOOL have_set_peerdn;
83 const struct host_item *host;
84 uschar *peerdn;
85 uschar *ciphersuite;
86 uschar *received_sni;
87
88 const uschar *tls_certificate;
89 const uschar *tls_privatekey;
90 const uschar *tls_sni; /* client send only, not received */
91 const uschar *tls_verify_certificates;
92 const uschar *tls_crl;
93 const uschar *tls_require_ciphers;
94 uschar *exp_tls_certificate;
95 uschar *exp_tls_privatekey;
96 uschar *exp_tls_sni;
97 uschar *exp_tls_verify_certificates;
98 uschar *exp_tls_crl;
99 uschar *exp_tls_require_ciphers;
100
101 tls_support *tlsp; /* set in tls_init() */
102
103 uschar *xfer_buffer;
104 int xfer_buffer_lwm;
105 int xfer_buffer_hwm;
106 int xfer_eof;
107 int xfer_error;
108 } exim_gnutls_state_st;
109
110 static const exim_gnutls_state_st exim_gnutls_state_init = {
111 NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, FALSE,
112 NULL, NULL, NULL, NULL,
113 NULL, NULL, NULL, NULL, NULL, NULL,
114 NULL, NULL, NULL, NULL, NULL, NULL,
115 NULL,
116 NULL, 0, 0, 0, 0,
117 };
118
119 /* Not only do we have our own APIs which don't pass around state, assuming
120 it's held in globals, GnuTLS doesn't appear to let us register callback data
121 for callbacks, or as part of the session, so we have to keep a "this is the
122 context we're currently dealing with" pointer and rely upon being
123 single-threaded to keep from processing data on an inbound TLS connection while
124 talking to another TLS connection for an outbound check. This does mean that
125 there's no way for heart-beats to be responded to, for the duration of the
126 second connection. */
127
128 static exim_gnutls_state_st state_server, state_client;
129
130 /* dh_params are initialised once within the lifetime of a process using TLS;
131 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
132 don't want to repeat this. */
133
134 static gnutls_dh_params_t dh_server_params = NULL;
135
136 /* No idea how this value was chosen; preserving it. Default is 3600. */
137
138 static const int ssl_session_timeout = 200;
139
140 static const char * const exim_default_gnutls_priority = "NORMAL";
141
142 /* Guard library core initialisation */
143
144 static BOOL exim_gnutls_base_init_done = FALSE;
145
146
147 /* ------------------------------------------------------------------------ */
148 /* macros */
149
150 #define MAX_HOST_LEN 255
151
152 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
153 the library logging; a value less than 0 disables the calls to set up logging
154 callbacks. */
155 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
156 #define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
157 #endif
158
159 #ifndef EXIM_CLIENT_DH_MIN_BITS
160 #define EXIM_CLIENT_DH_MIN_BITS 1024
161 #endif
162
163 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
164 can ask for a bit-strength. Without that, we stick to the constant we had
165 before, for now. */
166 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
167 #define EXIM_SERVER_DH_BITS_PRE2_12 1024
168 #endif
169
170 #define exim_gnutls_err_check(Label) do { \
171 if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0)
172
173 #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname)
174
175 #if GNUTLS_VERSION_NUMBER >= 0x020c00
176 #define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
177 #define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
178 #define HAVE_GNUTLS_RND
179 #define HAVE_GNUTLS_PKCS11
180 #endif
181
182
183
184
185 /* ------------------------------------------------------------------------ */
186 /* Callback declarations */
187
188 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
189 static void exim_gnutls_logger_cb(int level, const char *message);
190 #endif
191
192 static int exim_sni_handling_cb(gnutls_session_t session);
193
194
195
196
197 /* ------------------------------------------------------------------------ */
198 /* Static functions */
199
200 /*************************************************
201 * Handle TLS error *
202 *************************************************/
203
204 /* Called from lots of places when errors occur before actually starting to do
205 the TLS handshake, that is, while the session is still in clear. Always returns
206 DEFER for a server and FAIL for a client so that most calls can use "return
207 tls_error(...)" to do this processing and then give an appropriate return. A
208 single function is used for both server and client, because it is called from
209 some shared functions.
210
211 Argument:
212 prefix text to include in the logged error
213 msg additional error string (may be NULL)
214 usually obtained from gnutls_strerror()
215 host NULL if setting up a server;
216 the connected host if setting up a client
217
218 Returns: OK/DEFER/FAIL
219 */
220
221 static int
222 tls_error(const uschar *prefix, const char *msg, const host_item *host)
223 {
224 if (host)
225 {
226 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s",
227 host->name, host->address, prefix, msg ? ": " : "", msg ? msg : "");
228 return FAIL;
229 }
230 else
231 {
232 uschar *conn_info = smtp_get_connection_info();
233 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
234 conn_info += 5;
235 log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s",
236 conn_info, prefix, msg ? ": " : "", msg ? msg : "");
237 return DEFER;
238 }
239 }
240
241
242
243
244 /*************************************************
245 * Deal with logging errors during I/O *
246 *************************************************/
247
248 /* We have to get the identity of the peer from saved data.
249
250 Argument:
251 state the current GnuTLS exim state container
252 rc the GnuTLS error code, or 0 if it's a local error
253 when text identifying read or write
254 text local error text when ec is 0
255
256 Returns: nothing
257 */
258
259 static void
260 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
261 {
262 const char *msg;
263
264 if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
265 msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc),
266 US gnutls_alert_get_name(gnutls_alert_get(state->session)));
267 else
268 msg = gnutls_strerror(rc);
269
270 tls_error(when, msg, state->host);
271 }
272
273
274
275
276 /*************************************************
277 * Set various Exim expansion vars *
278 *************************************************/
279
280 /* We set various Exim global variables from the state, once a session has
281 been established. With TLS callouts, may need to change this to stack
282 variables, or just re-call it with the server state after client callout
283 has finished.
284
285 Make sure anything set here is inset in tls_getc().
286
287 Sets:
288 tls_active fd
289 tls_bits strength indicator
290 tls_certificate_verified bool indicator
291 tls_channelbinding_b64 for some SASL mechanisms
292 tls_cipher a string
293 tls_peerdn a string
294 tls_sni a (UTF-8) string
295
296 Argument:
297 state the relevant exim_gnutls_state_st *
298 */
299
300 static void
301 extract_exim_vars_from_tls_state(exim_gnutls_state_st *state, BOOL is_server)
302 {
303 gnutls_cipher_algorithm_t cipher;
304 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
305 int old_pool;
306 int rc;
307 gnutls_datum_t channel;
308 #endif
309
310 state->tlsp->active = state->fd_out;
311
312 cipher = gnutls_cipher_get(state->session);
313 /* returns size in "bytes" */
314 state->tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
315
316 state->tlsp->cipher = state->ciphersuite;
317
318 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
319
320 state->tlsp->certificate_verified = state->peer_cert_verified;
321
322 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
323 only available for use for authenticators while this TLS session is running. */
324
325 tls_channelbinding_b64 = NULL;
326 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
327 channel.data = NULL;
328 channel.size = 0;
329 rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel);
330 if (rc) {
331 DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc));
332 } else {
333 old_pool = store_pool;
334 store_pool = POOL_PERM;
335 tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size);
336 store_pool = old_pool;
337 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
338 }
339 #endif
340
341 state->tlsp->peerdn = state->peerdn;
342 state->tlsp->sni = state->received_sni;
343 }
344
345
346
347
348 /*************************************************
349 * Setup up DH parameters *
350 *************************************************/
351
352 /* Generating the D-H parameters may take a long time. They only need to
353 be re-generated every so often, depending on security policy. What we do is to
354 keep these parameters in a file in the spool directory. If the file does not
355 exist, we generate them. This means that it is easy to cause a regeneration.
356
357 The new file is written as a temporary file and renamed, so that an incomplete
358 file is never present. If two processes both compute some new parameters, you
359 waste a bit of effort, but it doesn't seem worth messing around with locking to
360 prevent this.
361
362 Returns: OK/DEFER/FAIL
363 */
364
365 static int
366 init_server_dh(void)
367 {
368 int fd, rc;
369 unsigned int dh_bits;
370 gnutls_datum m;
371 uschar filename_buf[PATH_MAX];
372 uschar *filename = NULL;
373 size_t sz;
374 uschar *exp_tls_dhparam;
375 BOOL use_file_in_spool = FALSE;
376 BOOL use_fixed_file = FALSE;
377 host_item *host = NULL; /* dummy for macros */
378
379 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n");
380
381 rc = gnutls_dh_params_init(&dh_server_params);
382 exim_gnutls_err_check(US"gnutls_dh_params_init");
383
384 m.data = NULL;
385 m.size = 0;
386
387 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam))
388 return DEFER;
389
390 if (!exp_tls_dhparam)
391 {
392 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
393 m.data = US std_dh_prime_default();
394 m.size = Ustrlen(m.data);
395 }
396 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
397 use_file_in_spool = TRUE;
398 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
399 {
400 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
401 return OK;
402 }
403 else if (exp_tls_dhparam[0] != '/')
404 {
405 m.data = US std_dh_prime_named(exp_tls_dhparam);
406 if (m.data == NULL)
407 return tls_error(US"No standard prime named", CS exp_tls_dhparam, NULL);
408 m.size = Ustrlen(m.data);
409 }
410 else
411 {
412 use_fixed_file = TRUE;
413 filename = exp_tls_dhparam;
414 }
415
416 if (m.data)
417 {
418 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
419 exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3");
420 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
421 return OK;
422 }
423
424 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
425 /* If you change this constant, also change dh_param_fn_ext so that we can use a
426 different filename and ensure we have sufficient bits. */
427 dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL);
428 if (!dh_bits)
429 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL);
430 DEBUG(D_tls)
431 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
432 dh_bits);
433 #else
434 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
435 DEBUG(D_tls)
436 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
437 dh_bits);
438 #endif
439
440 /* Some clients have hard-coded limits. */
441 if (dh_bits > tls_dh_max_bits)
442 {
443 DEBUG(D_tls)
444 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
445 tls_dh_max_bits);
446 dh_bits = tls_dh_max_bits;
447 }
448
449 if (use_file_in_spool)
450 {
451 if (!string_format(filename_buf, sizeof(filename_buf),
452 "%s/gnutls-params-%d", spool_directory, dh_bits))
453 return tls_error(US"overlong filename", NULL, NULL);
454 filename = filename_buf;
455 }
456
457 /* Open the cache file for reading and if successful, read it and set up the
458 parameters. */
459
460 fd = Uopen(filename, O_RDONLY, 0);
461 if (fd >= 0)
462 {
463 struct stat statbuf;
464 FILE *fp;
465 int saved_errno;
466
467 if (fstat(fd, &statbuf) < 0) /* EIO */
468 {
469 saved_errno = errno;
470 (void)close(fd);
471 return tls_error(US"TLS cache stat failed", strerror(saved_errno), NULL);
472 }
473 if (!S_ISREG(statbuf.st_mode))
474 {
475 (void)close(fd);
476 return tls_error(US"TLS cache not a file", NULL, NULL);
477 }
478 fp = fdopen(fd, "rb");
479 if (!fp)
480 {
481 saved_errno = errno;
482 (void)close(fd);
483 return tls_error(US"fdopen(TLS cache stat fd) failed",
484 strerror(saved_errno), NULL);
485 }
486
487 m.size = statbuf.st_size;
488 m.data = malloc(m.size);
489 if (m.data == NULL)
490 {
491 fclose(fp);
492 return tls_error(US"malloc failed", strerror(errno), NULL);
493 }
494 sz = fread(m.data, m.size, 1, fp);
495 if (!sz)
496 {
497 saved_errno = errno;
498 fclose(fp);
499 free(m.data);
500 return tls_error(US"fread failed", strerror(saved_errno), NULL);
501 }
502 fclose(fp);
503
504 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
505 free(m.data);
506 exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3");
507 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
508 }
509
510 /* If the file does not exist, fall through to compute new data and cache it.
511 If there was any other opening error, it is serious. */
512
513 else if (errno == ENOENT)
514 {
515 rc = -1;
516 DEBUG(D_tls)
517 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
518 }
519 else
520 return tls_error(string_open_failed(errno, "\"%s\" for reading", filename),
521 NULL, NULL);
522
523 /* If ret < 0, either the cache file does not exist, or the data it contains
524 is not useful. One particular case of this is when upgrading from an older
525 release of Exim in which the data was stored in a different format. We don't
526 try to be clever and support both formats; we just regenerate new data in this
527 case. */
528
529 if (rc < 0)
530 {
531 uschar *temp_fn;
532 unsigned int dh_bits_gen = dh_bits;
533
534 if ((PATH_MAX - Ustrlen(filename)) < 10)
535 return tls_error(US"Filename too long to generate replacement",
536 CS filename, NULL);
537
538 temp_fn = string_copy(US "%s.XXXXXXX");
539 fd = mkstemp(CS temp_fn); /* modifies temp_fn */
540 if (fd < 0)
541 return tls_error(US"Unable to open temp file", strerror(errno), NULL);
542 (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */
543
544 /* GnuTLS overshoots!
545 * If we ask for 2236, we might get 2237 or more.
546 * But there's no way to ask GnuTLS how many bits there really are.
547 * We can ask how many bits were used in a TLS session, but that's it!
548 * The prime itself is hidden behind too much abstraction.
549 * So we ask for less, and proceed on a wing and a prayer.
550 * First attempt, subtracted 3 for 2233 and got 2240.
551 */
552 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
553 {
554 dh_bits_gen = dh_bits - 10;
555 DEBUG(D_tls)
556 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
557 dh_bits_gen);
558 }
559
560 DEBUG(D_tls)
561 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
562 dh_bits_gen);
563 rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen);
564 exim_gnutls_err_check(US"gnutls_dh_params_generate2");
565
566 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
567 and I confirmed that a NULL call to get the size first is how the GnuTLS
568 sample apps handle this. */
569
570 sz = 0;
571 m.data = NULL;
572 rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
573 m.data, &sz);
574 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
575 exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing");
576 m.size = sz;
577 m.data = malloc(m.size);
578 if (m.data == NULL)
579 return tls_error(US"memory allocation failed", strerror(errno), NULL);
580 /* this will return a size 1 less than the allocation size above */
581 rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
582 m.data, &sz);
583 if (rc != GNUTLS_E_SUCCESS)
584 {
585 free(m.data);
586 exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real");
587 }
588 m.size = sz; /* shrink by 1, probably */
589
590 sz = write_to_fd_buf(fd, m.data, (size_t) m.size);
591 if (sz != m.size)
592 {
593 free(m.data);
594 return tls_error(US"TLS cache write D-H params failed",
595 strerror(errno), NULL);
596 }
597 free(m.data);
598 sz = write_to_fd_buf(fd, US"\n", 1);
599 if (sz != 1)
600 return tls_error(US"TLS cache write D-H params final newline failed",
601 strerror(errno), NULL);
602
603 rc = close(fd);
604 if (rc)
605 return tls_error(US"TLS cache write close() failed",
606 strerror(errno), NULL);
607
608 if (Urename(temp_fn, filename) < 0)
609 return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"",
610 temp_fn, filename), strerror(errno), NULL);
611
612 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
613 }
614
615 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
616 return OK;
617 }
618
619
620
621
622 /*************************************************
623 * Variables re-expanded post-SNI *
624 *************************************************/
625
626 /* Called from both server and client code, via tls_init(), and also from
627 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
628
629 We can tell the two apart by state->received_sni being non-NULL in callback.
630
631 The callback should not call us unless state->trigger_sni_changes is true,
632 which we are responsible for setting on the first pass through.
633
634 Arguments:
635 state exim_gnutls_state_st *
636
637 Returns: OK/DEFER/FAIL
638 */
639
640 static int
641 tls_expand_session_files(exim_gnutls_state_st *state)
642 {
643 struct stat statbuf;
644 int rc;
645 const host_item *host = state->host; /* macro should be reconsidered? */
646 uschar *saved_tls_certificate = NULL;
647 uschar *saved_tls_privatekey = NULL;
648 uschar *saved_tls_verify_certificates = NULL;
649 uschar *saved_tls_crl = NULL;
650 int cert_count;
651
652 /* We check for tls_sni *before* expansion. */
653 if (!state->host)
654 {
655 if (!state->received_sni)
656 {
657 if (state->tls_certificate &&
658 (Ustrstr(state->tls_certificate, US"tls_sni") ||
659 Ustrstr(state->tls_certificate, US"tls_in_sni") ||
660 Ustrstr(state->tls_certificate, US"tls_out_sni")
661 ))
662 {
663 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
664 state->trigger_sni_changes = TRUE;
665 }
666 }
667 else
668 {
669 /* useful for debugging */
670 saved_tls_certificate = state->exp_tls_certificate;
671 saved_tls_privatekey = state->exp_tls_privatekey;
672 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
673 saved_tls_crl = state->exp_tls_crl;
674 }
675 }
676
677 rc = gnutls_certificate_allocate_credentials(&state->x509_cred);
678 exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials");
679
680 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
681 state members, assuming consistent naming; and expand_check() returns
682 false if expansion failed, unless expansion was forced to fail. */
683
684 /* check if we at least have a certificate, before doing expensive
685 D-H generation. */
686
687 if (!expand_check_tlsvar(tls_certificate))
688 return DEFER;
689
690 /* certificate is mandatory in server, optional in client */
691
692 if ((state->exp_tls_certificate == NULL) ||
693 (*state->exp_tls_certificate == '\0'))
694 {
695 if (state->host == NULL)
696 return tls_error(US"no TLS server certificate is specified", NULL, NULL);
697 else
698 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
699 }
700
701 if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey))
702 return DEFER;
703
704 /* tls_privatekey is optional, defaulting to same file as certificate */
705
706 if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
707 {
708 state->tls_privatekey = state->tls_certificate;
709 state->exp_tls_privatekey = state->exp_tls_certificate;
710 }
711
712
713 if (state->exp_tls_certificate && *state->exp_tls_certificate)
714 {
715 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
716 state->exp_tls_certificate, state->exp_tls_privatekey);
717
718 if (state->received_sni)
719 {
720 if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) &&
721 (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0))
722 {
723 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
724 }
725 else
726 {
727 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
728 }
729 }
730
731 rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
732 CS state->exp_tls_certificate, CS state->exp_tls_privatekey,
733 GNUTLS_X509_FMT_PEM);
734 exim_gnutls_err_check(
735 string_sprintf("cert/key setup: cert=%s key=%s",
736 state->exp_tls_certificate, state->exp_tls_privatekey));
737 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
738 } /* tls_certificate */
739
740 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
741 provided. Experiment shows that, if the certificate file is empty, an unhelpful
742 error message is provided. However, if we just refrain from setting anything up
743 in that case, certificate verification fails, which seems to be the correct
744 behaviour. */
745
746 if (state->tls_verify_certificates && *state->tls_verify_certificates)
747 {
748 if (!expand_check_tlsvar(tls_verify_certificates))
749 return DEFER;
750 if (state->tls_crl && *state->tls_crl)
751 if (!expand_check_tlsvar(tls_crl))
752 return DEFER;
753
754 if (!(state->exp_tls_verify_certificates &&
755 *state->exp_tls_verify_certificates))
756 {
757 DEBUG(D_tls)
758 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
759 /* With no tls_verify_certificates, we ignore tls_crl too */
760 return OK;
761 }
762 }
763 else
764 {
765 DEBUG(D_tls)
766 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
767 return OK;
768 }
769
770 if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
771 {
772 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
773 "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
774 strerror(errno));
775 return DEFER;
776 }
777
778 /* The test suite passes in /dev/null; we could check for that path explicitly,
779 but who knows if someone has some weird FIFO which always dumps some certs, or
780 other weirdness. The thing we really want to check is that it's not a
781 directory, since while OpenSSL supports that, GnuTLS does not.
782 So s/!S_ISREG/S_ISDIR/ and change some messsaging ... */
783 if (S_ISDIR(statbuf.st_mode))
784 {
785 DEBUG(D_tls)
786 debug_printf("verify certificates path is a dir: \"%s\"\n",
787 state->exp_tls_verify_certificates);
788 log_write(0, LOG_MAIN|LOG_PANIC,
789 "tls_verify_certificates \"%s\" is a directory",
790 state->exp_tls_verify_certificates);
791 return DEFER;
792 }
793
794 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
795 state->exp_tls_verify_certificates, statbuf.st_size);
796
797 if (statbuf.st_size == 0)
798 {
799 DEBUG(D_tls)
800 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
801 return OK;
802 }
803
804 cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred,
805 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
806 if (cert_count < 0)
807 {
808 rc = cert_count;
809 exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file");
810 }
811 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count);
812
813 if (state->tls_crl && *state->tls_crl &&
814 state->exp_tls_crl && *state->exp_tls_crl)
815 {
816 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
817 cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
818 CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM);
819 if (cert_count < 0)
820 {
821 rc = cert_count;
822 exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file");
823 }
824 DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
825 }
826
827 return OK;
828 }
829
830
831
832
833 /*************************************************
834 * Set X.509 state variables *
835 *************************************************/
836
837 /* In GnuTLS, the registered cert/key are not replaced by a later
838 set of a cert/key, so for SNI support we need a whole new x509_cred
839 structure. Which means various other non-re-expanded pieces of state
840 need to be re-set in the new struct, so the setting logic is pulled
841 out to this.
842
843 Arguments:
844 state exim_gnutls_state_st *
845
846 Returns: OK/DEFER/FAIL
847 */
848
849 static int
850 tls_set_remaining_x509(exim_gnutls_state_st *state)
851 {
852 int rc;
853 const host_item *host = state->host; /* macro should be reconsidered? */
854
855 /* Create D-H parameters, or read them from the cache file. This function does
856 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
857 client-side params. */
858
859 if (!state->host)
860 {
861 if (!dh_server_params)
862 {
863 rc = init_server_dh();
864 if (rc != OK) return rc;
865 }
866 gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
867 }
868
869 /* Link the credentials to the session. */
870
871 rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred);
872 exim_gnutls_err_check(US"gnutls_credentials_set");
873
874 return OK;
875 }
876
877 /*************************************************
878 * Initialize for GnuTLS *
879 *************************************************/
880
881 /* Called from both server and client code. In the case of a server, errors
882 before actual TLS negotiation return DEFER.
883
884 Arguments:
885 host connected host, if client; NULL if server
886 certificate certificate file
887 privatekey private key file
888 sni TLS SNI to send, sometimes when client; else NULL
889 cas CA certs file
890 crl CRL file
891 require_ciphers tls_require_ciphers setting
892 caller_state returned state-info structure
893
894 Returns: OK/DEFER/FAIL
895 */
896
897 static int
898 tls_init(
899 const host_item *host,
900 const uschar *certificate,
901 const uschar *privatekey,
902 const uschar *sni,
903 const uschar *cas,
904 const uschar *crl,
905 const uschar *require_ciphers,
906 exim_gnutls_state_st **caller_state)
907 {
908 exim_gnutls_state_st *state;
909 int rc;
910 size_t sz;
911 const char *errpos;
912 uschar *p;
913 BOOL want_default_priorities;
914
915 if (!exim_gnutls_base_init_done)
916 {
917 DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
918
919 #ifdef HAVE_GNUTLS_PKCS11
920 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
921 which loads modules from a config file, which sounds good and may be wanted
922 by some sysadmin, but also means in common configurations that GNOME keyring
923 environment variables are used and so breaks for users calling mailq.
924 To prevent this, we init PKCS11 first, which is the documented approach. */
925 if (!gnutls_enable_pkcs11)
926 {
927 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
928 exim_gnutls_err_check(US"gnutls_pkcs11_init");
929 }
930 #endif
931
932 rc = gnutls_global_init();
933 exim_gnutls_err_check(US"gnutls_global_init");
934
935 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
936 DEBUG(D_tls)
937 {
938 gnutls_global_set_log_function(exim_gnutls_logger_cb);
939 /* arbitrarily chosen level; bump upto 9 for more */
940 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
941 }
942 #endif
943
944 exim_gnutls_base_init_done = TRUE;
945 }
946
947 if (host)
948 {
949 state = &state_client;
950 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
951 state->tlsp = &tls_out;
952 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
953 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
954 }
955 else
956 {
957 state = &state_server;
958 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
959 state->tlsp = &tls_in;
960 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
961 rc = gnutls_init(&state->session, GNUTLS_SERVER);
962 }
963 exim_gnutls_err_check(US"gnutls_init");
964
965 state->host = host;
966
967 state->tls_certificate = certificate;
968 state->tls_privatekey = privatekey;
969 state->tls_require_ciphers = require_ciphers;
970 state->tls_sni = sni;
971 state->tls_verify_certificates = cas;
972 state->tls_crl = crl;
973
974 /* This handles the variables that might get re-expanded after TLS SNI;
975 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
976
977 DEBUG(D_tls)
978 debug_printf("Expanding various TLS configuration options for session credentials.\n");
979 rc = tls_expand_session_files(state);
980 if (rc != OK) return rc;
981
982 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
983 requires a new structure afterwards. */
984
985 rc = tls_set_remaining_x509(state);
986 if (rc != OK) return rc;
987
988 /* set SNI in client, only */
989 if (host)
990 {
991 if (!expand_check(state->tlsp->sni, US"tls_out_sni", &state->exp_tls_sni))
992 return DEFER;
993 if (state->exp_tls_sni && *state->exp_tls_sni)
994 {
995 DEBUG(D_tls)
996 debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni);
997 sz = Ustrlen(state->exp_tls_sni);
998 rc = gnutls_server_name_set(state->session,
999 GNUTLS_NAME_DNS, state->exp_tls_sni, sz);
1000 exim_gnutls_err_check(US"gnutls_server_name_set");
1001 }
1002 }
1003 else if (state->tls_sni)
1004 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
1005 "have an SNI set for a client [%s]\n", state->tls_sni);
1006
1007 /* This is the priority string support,
1008 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1009 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1010 This was backwards incompatible, but means Exim no longer needs to track
1011 all algorithms and provide string forms for them. */
1012
1013 want_default_priorities = TRUE;
1014
1015 if (state->tls_require_ciphers && *state->tls_require_ciphers)
1016 {
1017 if (!expand_check_tlsvar(tls_require_ciphers))
1018 return DEFER;
1019 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
1020 {
1021 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n",
1022 state->exp_tls_require_ciphers);
1023
1024 rc = gnutls_priority_init(&state->priority_cache,
1025 CS state->exp_tls_require_ciphers, &errpos);
1026 want_default_priorities = FALSE;
1027 p = state->exp_tls_require_ciphers;
1028 }
1029 }
1030 if (want_default_priorities)
1031 {
1032 DEBUG(D_tls)
1033 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n",
1034 exim_default_gnutls_priority);
1035 rc = gnutls_priority_init(&state->priority_cache,
1036 exim_default_gnutls_priority, &errpos);
1037 p = US exim_default_gnutls_priority;
1038 }
1039
1040 exim_gnutls_err_check(string_sprintf(
1041 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1042 p, errpos - CS p, errpos));
1043
1044 rc = gnutls_priority_set(state->session, state->priority_cache);
1045 exim_gnutls_err_check(US"gnutls_priority_set");
1046
1047 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
1048
1049 /* Reduce security in favour of increased compatibility, if the admin
1050 decides to make that trade-off. */
1051 if (gnutls_compat_mode)
1052 {
1053 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1054 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
1055 gnutls_session_enable_compatibility_mode(state->session);
1056 #else
1057 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1058 #endif
1059 }
1060
1061 *caller_state = state;
1062 return OK;
1063 }
1064
1065
1066
1067
1068 /*************************************************
1069 * Extract peer information *
1070 *************************************************/
1071
1072 /* Called from both server and client code.
1073 Only this is allowed to set state->peerdn and state->have_set_peerdn
1074 and we use that to detect double-calls.
1075
1076 NOTE: the state blocks last while the TLS connection is up, which is fine
1077 for logging in the server side, but for the client side, we log after teardown
1078 in src/deliver.c. While the session is up, we can twist about states and
1079 repoint tls_* globals, but those variables used for logging or other variable
1080 expansion that happens _after_ delivery need to have a longer life-time.
1081
1082 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1083 doing this more than once per generation of a state context. We set them in
1084 the state context, and repoint tls_* to them. After the state goes away, the
1085 tls_* copies of the pointers remain valid and client delivery logging is happy.
1086
1087 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1088 don't apply.
1089
1090 Arguments:
1091 state exim_gnutls_state_st *
1092
1093 Returns: OK/DEFER/FAIL
1094 */
1095
1096 static int
1097 peer_status(exim_gnutls_state_st *state)
1098 {
1099 uschar cipherbuf[256];
1100 const gnutls_datum *cert_list;
1101 int old_pool, rc;
1102 unsigned int cert_list_size = 0;
1103 gnutls_protocol_t protocol;
1104 gnutls_cipher_algorithm_t cipher;
1105 gnutls_kx_algorithm_t kx;
1106 gnutls_mac_algorithm_t mac;
1107 gnutls_certificate_type_t ct;
1108 gnutls_x509_crt_t crt;
1109 uschar *p, *dn_buf;
1110 size_t sz;
1111
1112 if (state->have_set_peerdn)
1113 return OK;
1114 state->have_set_peerdn = TRUE;
1115
1116 state->peerdn = NULL;
1117
1118 /* tls_cipher */
1119 cipher = gnutls_cipher_get(state->session);
1120 protocol = gnutls_protocol_get_version(state->session);
1121 mac = gnutls_mac_get(state->session);
1122 kx = gnutls_kx_get(state->session);
1123
1124 string_format(cipherbuf, sizeof(cipherbuf),
1125 "%s:%s:%d",
1126 gnutls_protocol_get_name(protocol),
1127 gnutls_cipher_suite_get_name(kx, cipher, mac),
1128 (int) gnutls_cipher_get_key_size(cipher) * 8);
1129
1130 /* I don't see a way that spaces could occur, in the current GnuTLS
1131 code base, but it was a concern in the old code and perhaps older GnuTLS
1132 releases did return "TLS 1.0"; play it safe, just in case. */
1133 for (p = cipherbuf; *p != '\0'; ++p)
1134 if (isspace(*p))
1135 *p = '-';
1136 old_pool = store_pool;
1137 store_pool = POOL_PERM;
1138 state->ciphersuite = string_copy(cipherbuf);
1139 store_pool = old_pool;
1140 state->tlsp->cipher = state->ciphersuite;
1141
1142 /* tls_peerdn */
1143 cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size);
1144
1145 if (cert_list == NULL || cert_list_size == 0)
1146 {
1147 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1148 cert_list, cert_list_size);
1149 if (state->verify_requirement == VERIFY_REQUIRED)
1150 return tls_error(US"certificate verification failed",
1151 "no certificate received from peer", state->host);
1152 return OK;
1153 }
1154
1155 ct = gnutls_certificate_type_get(state->session);
1156 if (ct != GNUTLS_CRT_X509)
1157 {
1158 const char *ctn = gnutls_certificate_type_get_name(ct);
1159 DEBUG(D_tls)
1160 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
1161 if (state->verify_requirement == VERIFY_REQUIRED)
1162 return tls_error(US"certificate verification not possible, unhandled type",
1163 ctn, state->host);
1164 return OK;
1165 }
1166
1167 #define exim_gnutls_peer_err(Label) do { \
1168 if (rc != GNUTLS_E_SUCCESS) { \
1169 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", (Label), gnutls_strerror(rc)); \
1170 if (state->verify_requirement == VERIFY_REQUIRED) { return tls_error((Label), gnutls_strerror(rc), state->host); } \
1171 return OK; } } while (0)
1172
1173 rc = gnutls_x509_crt_init(&crt);
1174 exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)");
1175
1176 rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER);
1177 exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]");
1178 sz = 0;
1179 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
1180 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
1181 {
1182 exim_gnutls_peer_err(US"getting size for cert DN failed");
1183 return FAIL; /* should not happen */
1184 }
1185 dn_buf = store_get_perm(sz);
1186 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
1187 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1188 state->peerdn = dn_buf;
1189
1190 return OK;
1191 #undef exim_gnutls_peer_err
1192 }
1193
1194
1195
1196
1197 /*************************************************
1198 * Verify peer certificate *
1199 *************************************************/
1200
1201 /* Called from both server and client code.
1202 *Should* be using a callback registered with
1203 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1204 the peer information, but that's too new for some OSes.
1205
1206 Arguments:
1207 state exim_gnutls_state_st *
1208 error where to put an error message
1209
1210 Returns:
1211 FALSE if the session should be rejected
1212 TRUE if the cert is okay or we just don't care
1213 */
1214
1215 static BOOL
1216 verify_certificate(exim_gnutls_state_st *state, const char **error)
1217 {
1218 int rc;
1219 unsigned int verify;
1220
1221 *error = NULL;
1222
1223 rc = peer_status(state);
1224 if (rc != OK)
1225 {
1226 verify = GNUTLS_CERT_INVALID;
1227 *error = "not supplied";
1228 }
1229 else
1230 {
1231 rc = gnutls_certificate_verify_peers2(state->session, &verify);
1232 }
1233
1234 /* Handle the result of verification. INVALID seems to be set as well
1235 as REVOKED, but leave the test for both. */
1236
1237 if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0)
1238 {
1239 state->peer_cert_verified = FALSE;
1240 if (*error == NULL)
1241 *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid";
1242
1243 DEBUG(D_tls)
1244 debug_printf("TLS certificate verification failed (%s): peerdn=%s\n",
1245 *error, state->peerdn ? state->peerdn : US"<unset>");
1246
1247 if (state->verify_requirement == VERIFY_REQUIRED)
1248 {
1249 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
1250 return FALSE;
1251 }
1252 DEBUG(D_tls)
1253 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1254 }
1255 else
1256 {
1257 state->peer_cert_verified = TRUE;
1258 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n",
1259 state->peerdn ? state->peerdn : US"<unset>");
1260 }
1261
1262 state->tlsp->peerdn = state->peerdn;
1263
1264 return TRUE;
1265 }
1266
1267
1268
1269
1270 /* ------------------------------------------------------------------------ */
1271 /* Callbacks */
1272
1273 /* Logging function which can be registered with
1274 * gnutls_global_set_log_function()
1275 * gnutls_global_set_log_level() 0..9
1276 */
1277 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1278 static void
1279 exim_gnutls_logger_cb(int level, const char *message)
1280 {
1281 size_t len = strlen(message);
1282 if (len < 1)
1283 {
1284 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
1285 return;
1286 }
1287 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
1288 message[len-1] == '\n' ? "" : "\n");
1289 }
1290 #endif
1291
1292
1293 /* Called after client hello, should handle SNI work.
1294 This will always set tls_sni (state->received_sni) if available,
1295 and may trigger presenting different certificates,
1296 if state->trigger_sni_changes is TRUE.
1297
1298 Should be registered with
1299 gnutls_handshake_set_post_client_hello_function()
1300
1301 "This callback must return 0 on success or a gnutls error code to terminate the
1302 handshake.".
1303
1304 For inability to get SNI information, we return 0.
1305 We only return non-zero if re-setup failed.
1306 Only used for server-side TLS.
1307 */
1308
1309 static int
1310 exim_sni_handling_cb(gnutls_session_t session)
1311 {
1312 char sni_name[MAX_HOST_LEN];
1313 size_t data_len = MAX_HOST_LEN;
1314 exim_gnutls_state_st *state = &state_server;
1315 unsigned int sni_type;
1316 int rc, old_pool;
1317
1318 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
1319 if (rc != GNUTLS_E_SUCCESS)
1320 {
1321 DEBUG(D_tls) {
1322 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
1323 debug_printf("TLS: no SNI presented in handshake.\n");
1324 else
1325 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
1326 gnutls_strerror(rc), rc);
1327 };
1328 return 0;
1329 }
1330
1331 if (sni_type != GNUTLS_NAME_DNS)
1332 {
1333 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
1334 return 0;
1335 }
1336
1337 /* We now have a UTF-8 string in sni_name */
1338 old_pool = store_pool;
1339 store_pool = POOL_PERM;
1340 state->received_sni = string_copyn(US sni_name, data_len);
1341 store_pool = old_pool;
1342
1343 /* We set this one now so that variable expansions below will work */
1344 state->tlsp->sni = state->received_sni;
1345
1346 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
1347 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
1348
1349 if (!state->trigger_sni_changes)
1350 return 0;
1351
1352 rc = tls_expand_session_files(state);
1353 if (rc != OK)
1354 {
1355 /* If the setup of certs/etc failed before handshake, TLS would not have
1356 been offered. The best we can do now is abort. */
1357 return GNUTLS_E_APPLICATION_ERROR_MIN;
1358 }
1359
1360 rc = tls_set_remaining_x509(state);
1361 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
1362
1363 return 0;
1364 }
1365
1366
1367
1368
1369 /* ------------------------------------------------------------------------ */
1370 /* Exported functions */
1371
1372
1373
1374
1375 /*************************************************
1376 * Start a TLS session in a server *
1377 *************************************************/
1378
1379 /* This is called when Exim is running as a server, after having received
1380 the STARTTLS command. It must respond to that command, and then negotiate
1381 a TLS session.
1382
1383 Arguments:
1384 require_ciphers list of allowed ciphers or NULL
1385
1386 Returns: OK on success
1387 DEFER for errors before the start of the negotiation
1388 FAIL for errors during the negotation; the server can't
1389 continue running.
1390 */
1391
1392 int
1393 tls_server_start(const uschar *require_ciphers)
1394 {
1395 int rc;
1396 const char *error;
1397 exim_gnutls_state_st *state = NULL;
1398
1399 /* Check for previous activation */
1400 if (tls_in.active >= 0)
1401 {
1402 tls_error(US"STARTTLS received after TLS started", "", NULL);
1403 smtp_printf("554 Already in TLS\r\n");
1404 return FAIL;
1405 }
1406
1407 /* Initialize the library. If it fails, it will already have logged the error
1408 and sent an SMTP response. */
1409
1410 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
1411
1412 rc = tls_init(NULL, tls_certificate, tls_privatekey,
1413 NULL, tls_verify_certificates, tls_crl,
1414 require_ciphers, &state);
1415 if (rc != OK) return rc;
1416
1417 /* If this is a host for which certificate verification is mandatory or
1418 optional, set up appropriately. */
1419
1420 if (verify_check_host(&tls_verify_hosts) == OK)
1421 {
1422 DEBUG(D_tls) debug_printf("TLS: a client certificate will be required.\n");
1423 state->verify_requirement = VERIFY_REQUIRED;
1424 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
1425 }
1426 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1427 {
1428 DEBUG(D_tls) debug_printf("TLS: a client certificate will be requested but not required.\n");
1429 state->verify_requirement = VERIFY_OPTIONAL;
1430 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
1431 }
1432 else
1433 {
1434 DEBUG(D_tls) debug_printf("TLS: a client certificate will not be requested.\n");
1435 state->verify_requirement = VERIFY_NONE;
1436 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
1437 }
1438
1439 /* Register SNI handling; always, even if not in tls_certificate, so that the
1440 expansion variable $tls_sni is always available. */
1441
1442 gnutls_handshake_set_post_client_hello_function(state->session,
1443 exim_sni_handling_cb);
1444
1445 /* Set context and tell client to go ahead, except in the case of TLS startup
1446 on connection, where outputting anything now upsets the clients and tends to
1447 make them disconnect. We need to have an explicit fflush() here, to force out
1448 the response. Other smtp_printf() calls do not need it, because in non-TLS
1449 mode, the fflush() happens when smtp_getc() is called. */
1450
1451 if (!state->tlsp->on_connect)
1452 {
1453 smtp_printf("220 TLS go ahead\r\n");
1454 fflush(smtp_out); /*XXX JGH */
1455 }
1456
1457 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1458 that the GnuTLS library doesn't. */
1459
1460 gnutls_transport_set_ptr2(state->session,
1461 (gnutls_transport_ptr)fileno(smtp_in),
1462 (gnutls_transport_ptr)fileno(smtp_out));
1463 state->fd_in = fileno(smtp_in);
1464 state->fd_out = fileno(smtp_out);
1465
1466 sigalrm_seen = FALSE;
1467 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1468 do
1469 {
1470 rc = gnutls_handshake(state->session);
1471 } while ((rc == GNUTLS_E_AGAIN) ||
1472 (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen));
1473 alarm(0);
1474
1475 if (rc != GNUTLS_E_SUCCESS)
1476 {
1477 tls_error(US"gnutls_handshake",
1478 sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL);
1479 /* It seems that, except in the case of a timeout, we have to close the
1480 connection right here; otherwise if the other end is running OpenSSL it hangs
1481 until the server times out. */
1482
1483 if (!sigalrm_seen)
1484 {
1485 (void)fclose(smtp_out);
1486 (void)fclose(smtp_in);
1487 }
1488
1489 return FAIL;
1490 }
1491
1492 DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
1493
1494 /* Verify after the fact */
1495
1496 if (state->verify_requirement != VERIFY_NONE)
1497 {
1498 if (!verify_certificate(state, &error))
1499 {
1500 if (state->verify_requirement == VERIFY_OPTIONAL)
1501 {
1502 DEBUG(D_tls)
1503 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
1504 error);
1505 }
1506 else
1507 {
1508 tls_error(US"certificate verification failed", error, NULL);
1509 return FAIL;
1510 }
1511 }
1512 }
1513
1514 /* Figure out peer DN, and if authenticated, etc. */
1515
1516 rc = peer_status(state);
1517 if (rc != OK) return rc;
1518
1519 /* Sets various Exim expansion variables; always safe within server */
1520
1521 extract_exim_vars_from_tls_state(state, TRUE);
1522
1523 /* TLS has been set up. Adjust the input functions to read via TLS,
1524 and initialize appropriately. */
1525
1526 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1527
1528 receive_getc = tls_getc;
1529 receive_ungetc = tls_ungetc;
1530 receive_feof = tls_feof;
1531 receive_ferror = tls_ferror;
1532 receive_smtp_buffered = tls_smtp_buffered;
1533
1534 return OK;
1535 }
1536
1537
1538
1539
1540 /*************************************************
1541 * Start a TLS session in a client *
1542 *************************************************/
1543
1544 /* Called from the smtp transport after STARTTLS has been accepted.
1545
1546 Arguments:
1547 fd the fd of the connection
1548 host connected host (for messages)
1549 addr the first address (not used)
1550 certificate certificate file
1551 privatekey private key file
1552 sni TLS SNI to send to remote host
1553 verify_certs file for certificate verify
1554 verify_crl CRL for verify
1555 require_ciphers list of allowed ciphers or NULL
1556 dh_min_bits minimum number of bits acceptable in server's DH prime
1557 timeout startup timeout
1558
1559 Returns: OK/DEFER/FAIL (because using common functions),
1560 but for a client, DEFER and FAIL have the same meaning
1561 */
1562
1563 int
1564 tls_client_start(int fd, host_item *host,
1565 address_item *addr ARG_UNUSED,
1566 uschar *certificate, uschar *privatekey, uschar *sni,
1567 uschar *verify_certs, uschar *verify_crl,
1568 uschar *require_ciphers,
1569 #ifdef EXPERIMENTAL_OCSP
1570 uschar *require_ocsp ARG_UNUSED,
1571 #endif
1572 int dh_min_bits, int timeout)
1573 {
1574 int rc;
1575 const char *error;
1576 exim_gnutls_state_st *state = NULL;
1577
1578 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd);
1579
1580 rc = tls_init(host, certificate, privatekey,
1581 sni, verify_certs, verify_crl, require_ciphers, &state);
1582 if (rc != OK) return rc;
1583
1584 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
1585 {
1586 DEBUG(D_tls)
1587 debug_printf("WARNING: tls_dh_min_bits far too low, clamping %d up to %d\n",
1588 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
1589 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
1590 }
1591
1592 DEBUG(D_tls) debug_printf("Setting D-H prime minimum acceptable bits to %d\n",
1593 dh_min_bits);
1594 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
1595
1596 if (verify_certs == NULL)
1597 {
1598 DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n");
1599 state->verify_requirement = VERIFY_NONE;
1600 /* we still ask for it, to log it, etc */
1601 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
1602 }
1603 else
1604 {
1605 DEBUG(D_tls) debug_printf("TLS: server certificate verification required\n");
1606 state->verify_requirement = VERIFY_REQUIRED;
1607 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
1608 }
1609
1610 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd);
1611 state->fd_in = fd;
1612 state->fd_out = fd;
1613
1614 /* There doesn't seem to be a built-in timeout on connection. */
1615
1616 sigalrm_seen = FALSE;
1617 alarm(timeout);
1618 do
1619 {
1620 rc = gnutls_handshake(state->session);
1621 } while ((rc == GNUTLS_E_AGAIN) ||
1622 (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen));
1623 alarm(0);
1624
1625 if (rc != GNUTLS_E_SUCCESS)
1626 return tls_error(US"gnutls_handshake",
1627 sigalrm_seen ? "timed out" : gnutls_strerror(rc), state->host);
1628
1629 DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
1630
1631 /* Verify late */
1632
1633 if (state->verify_requirement != VERIFY_NONE &&
1634 !verify_certificate(state, &error))
1635 return tls_error(US"certificate verification failed", error, state->host);
1636
1637 /* Figure out peer DN, and if authenticated, etc. */
1638
1639 rc = peer_status(state);
1640 if (rc != OK) return rc;
1641
1642 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
1643
1644 extract_exim_vars_from_tls_state(state, FALSE);
1645
1646 return OK;
1647 }
1648
1649
1650
1651
1652 /*************************************************
1653 * Close down a TLS session *
1654 *************************************************/
1655
1656 /* This is also called from within a delivery subprocess forked from the
1657 daemon, to shut down the TLS library, without actually doing a shutdown (which
1658 would tamper with the TLS session in the parent process).
1659
1660 Arguments: TRUE if gnutls_bye is to be called
1661 Returns: nothing
1662 */
1663
1664 void
1665 tls_close(BOOL is_server, BOOL shutdown)
1666 {
1667 exim_gnutls_state_st *state = is_server ? &state_server : &state_client;
1668
1669 if (!state->tlsp || state->tlsp->active < 0) return; /* TLS was not active */
1670
1671 if (shutdown)
1672 {
1673 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n");
1674 gnutls_bye(state->session, GNUTLS_SHUT_WR);
1675 }
1676
1677 gnutls_deinit(state->session);
1678
1679 state->tlsp->active = -1;
1680 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1681
1682 if ((state_server.session == NULL) && (state_client.session == NULL))
1683 {
1684 gnutls_global_deinit();
1685 exim_gnutls_base_init_done = FALSE;
1686 }
1687
1688 }
1689
1690
1691
1692
1693 /*************************************************
1694 * TLS version of getc *
1695 *************************************************/
1696
1697 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1698 it refills the buffer via the GnuTLS reading function.
1699 Only used by the server-side TLS.
1700
1701 This feeds DKIM and should be used for all message-body reads.
1702
1703 Arguments: none
1704 Returns: the next character or EOF
1705 */
1706
1707 int
1708 tls_getc(void)
1709 {
1710 exim_gnutls_state_st *state = &state_server;
1711 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
1712 {
1713 ssize_t inbytes;
1714
1715 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
1716 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
1717
1718 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1719 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
1720 ssl_xfer_buffer_size);
1721 alarm(0);
1722
1723 /* A zero-byte return appears to mean that the TLS session has been
1724 closed down, not that the socket itself has been closed down. Revert to
1725 non-TLS handling. */
1726
1727 if (inbytes == 0)
1728 {
1729 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
1730
1731 receive_getc = smtp_getc;
1732 receive_ungetc = smtp_ungetc;
1733 receive_feof = smtp_feof;
1734 receive_ferror = smtp_ferror;
1735 receive_smtp_buffered = smtp_buffered;
1736
1737 gnutls_deinit(state->session);
1738 state->session = NULL;
1739 state->tlsp->active = -1;
1740 state->tlsp->bits = 0;
1741 state->tlsp->certificate_verified = FALSE;
1742 tls_channelbinding_b64 = NULL; /*XXX JGH */
1743 state->tlsp->cipher = NULL;
1744 state->tlsp->peerdn = NULL;
1745
1746 return smtp_getc();
1747 }
1748
1749 /* Handle genuine errors */
1750
1751 else if (inbytes < 0)
1752 {
1753 record_io_error(state, (int) inbytes, US"recv", NULL);
1754 state->xfer_error = 1;
1755 return EOF;
1756 }
1757 #ifndef DISABLE_DKIM
1758 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
1759 #endif
1760 state->xfer_buffer_hwm = (int) inbytes;
1761 state->xfer_buffer_lwm = 0;
1762 }
1763
1764 /* Something in the buffer; return next uschar */
1765
1766 return state->xfer_buffer[state->xfer_buffer_lwm++];
1767 }
1768
1769
1770
1771
1772 /*************************************************
1773 * Read bytes from TLS channel *
1774 *************************************************/
1775
1776 /* This does not feed DKIM, so if the caller uses this for reading message body,
1777 then the caller must feed DKIM.
1778
1779 Arguments:
1780 buff buffer of data
1781 len size of buffer
1782
1783 Returns: the number of bytes read
1784 -1 after a failed read
1785 */
1786
1787 int
1788 tls_read(BOOL is_server, uschar *buff, size_t len)
1789 {
1790 exim_gnutls_state_st *state = is_server ? &state_server : &state_client;
1791 ssize_t inbytes;
1792
1793 if (len > INT_MAX)
1794 len = INT_MAX;
1795
1796 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
1797 DEBUG(D_tls)
1798 debug_printf("*** PROBABLY A BUG *** " \
1799 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
1800 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
1801
1802 DEBUG(D_tls)
1803 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n",
1804 state->session, buff, len);
1805
1806 inbytes = gnutls_record_recv(state->session, buff, len);
1807 if (inbytes > 0) return inbytes;
1808 if (inbytes == 0)
1809 {
1810 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
1811 }
1812 else record_io_error(state, (int)inbytes, US"recv", NULL);
1813
1814 return -1;
1815 }
1816
1817
1818
1819
1820 /*************************************************
1821 * Write bytes down TLS channel *
1822 *************************************************/
1823
1824 /*
1825 Arguments:
1826 is_server channel specifier
1827 buff buffer of data
1828 len number of bytes
1829
1830 Returns: the number of bytes after a successful write,
1831 -1 after a failed write
1832 */
1833
1834 int
1835 tls_write(BOOL is_server, const uschar *buff, size_t len)
1836 {
1837 ssize_t outbytes;
1838 size_t left = len;
1839 exim_gnutls_state_st *state = is_server ? &state_server : &state_client;
1840
1841 DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left);
1842 while (left > 0)
1843 {
1844 DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n",
1845 buff, left);
1846 outbytes = gnutls_record_send(state->session, buff, left);
1847
1848 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
1849 if (outbytes < 0)
1850 {
1851 record_io_error(state, outbytes, US"send", NULL);
1852 return -1;
1853 }
1854 if (outbytes == 0)
1855 {
1856 record_io_error(state, 0, US"send", US"TLS channel closed on write");
1857 return -1;
1858 }
1859
1860 left -= outbytes;
1861 buff += outbytes;
1862 }
1863
1864 if (len > INT_MAX)
1865 {
1866 DEBUG(D_tls)
1867 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
1868 len);
1869 len = INT_MAX;
1870 }
1871
1872 return (int) len;
1873 }
1874
1875
1876
1877
1878 /*************************************************
1879 * Random number generation *
1880 *************************************************/
1881
1882 /* Pseudo-random number generation. The result is not expected to be
1883 cryptographically strong but not so weak that someone will shoot themselves
1884 in the foot using it as a nonce in input in some email header scheme or
1885 whatever weirdness they'll twist this into. The result should handle fork()
1886 and avoid repeating sequences. OpenSSL handles that for us.
1887
1888 Arguments:
1889 max range maximum
1890 Returns a random number in range [0, max-1]
1891 */
1892
1893 #ifdef HAVE_GNUTLS_RND
1894 int
1895 vaguely_random_number(int max)
1896 {
1897 unsigned int r;
1898 int i, needed_len;
1899 uschar *p;
1900 uschar smallbuf[sizeof(r)];
1901
1902 if (max <= 1)
1903 return 0;
1904
1905 needed_len = sizeof(r);
1906 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1907 * asked for a number less than 10. */
1908 for (r = max, i = 0; r; ++i)
1909 r >>= 1;
1910 i = (i + 7) / 8;
1911 if (i < needed_len)
1912 needed_len = i;
1913
1914 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
1915 if (i < 0)
1916 {
1917 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
1918 return vaguely_random_number_fallback(max);
1919 }
1920 r = 0;
1921 for (p = smallbuf; needed_len; --needed_len, ++p)
1922 {
1923 r *= 256;
1924 r += *p;
1925 }
1926
1927 /* We don't particularly care about weighted results; if someone wants
1928 * smooth distribution and cares enough then they should submit a patch then. */
1929 return r % max;
1930 }
1931 #else /* HAVE_GNUTLS_RND */
1932 int
1933 vaguely_random_number(int max)
1934 {
1935 return vaguely_random_number_fallback(max);
1936 }
1937 #endif /* HAVE_GNUTLS_RND */
1938
1939
1940
1941
1942 /*************************************************
1943 * Let tls_require_ciphers be checked at startup *
1944 *************************************************/
1945
1946 /* The tls_require_ciphers option, if set, must be something which the
1947 library can parse.
1948
1949 Returns: NULL on success, or error message
1950 */
1951
1952 uschar *
1953 tls_validate_require_cipher(void)
1954 {
1955 int rc;
1956 uschar *expciphers = NULL;
1957 gnutls_priority_t priority_cache;
1958 const char *errpos;
1959
1960 #define validate_check_rc(Label) do { \
1961 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
1962 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
1963 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
1964
1965 if (exim_gnutls_base_init_done)
1966 log_write(0, LOG_MAIN|LOG_PANIC,
1967 "already initialised GnuTLS, Exim developer bug");
1968
1969 #ifdef HAVE_GNUTLS_PKCS11
1970 if (!gnutls_enable_pkcs11)
1971 {
1972 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
1973 validate_check_rc(US"gnutls_pkcs11_init");
1974 }
1975 #endif
1976 rc = gnutls_global_init();
1977 validate_check_rc(US"gnutls_global_init()");
1978 exim_gnutls_base_init_done = TRUE;
1979
1980 if (!(tls_require_ciphers && *tls_require_ciphers))
1981 return_deinit(NULL);
1982
1983 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1984 return_deinit(US"failed to expand tls_require_ciphers");
1985
1986 if (!(expciphers && *expciphers))
1987 return_deinit(NULL);
1988
1989 DEBUG(D_tls)
1990 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1991
1992 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
1993 validate_check_rc(string_sprintf(
1994 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
1995 expciphers, errpos - CS expciphers, errpos));
1996
1997 #undef return_deinit
1998 #undef validate_check_rc
1999 gnutls_global_deinit();
2000
2001 return NULL;
2002 }
2003
2004
2005
2006
2007 /*************************************************
2008 * Report the library versions. *
2009 *************************************************/
2010
2011 /* See a description in tls-openssl.c for an explanation of why this exists.
2012
2013 Arguments: a FILE* to print the results to
2014 Returns: nothing
2015 */
2016
2017 void
2018 tls_version_report(FILE *f)
2019 {
2020 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
2021 " Runtime: %s\n",
2022 LIBGNUTLS_VERSION,
2023 gnutls_check_version(NULL));
2024 }
2025
2026 /* End of tls-gnu.c */