1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Copyright (c) Phil Pennock 2012 */
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.
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
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).
24 Keeping client and server variables more split than before and is currently
25 the norm, in anticipation of TLS in ACL callouts.
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.
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).
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 # define SUPPORT_PARAM_TO_PK_BITS
47 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
48 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
51 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
52 # warning "GnuTLS library version too old; tls:cert event unsupported"
53 # define DISABLE_EVENT
55 #if GNUTLS_VERSION_NUMBER >= 0x030306
56 # define SUPPORT_CA_DIR
58 # undef SUPPORT_CA_DIR
60 #if GNUTLS_VERSION_NUMBER >= 0x030014
61 # define SUPPORT_SYSDEFAULT_CABUNDLE
65 # include <gnutls/ocsp.h>
71 gnutls_global_set_audit_log_function()
74 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
77 /* Local static variables for GnuTLS */
79 /* Values for verify_requirement */
81 enum peer_verify_requirement
82 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
84 /* This holds most state for server or client; with this, we can set up an
85 outbound TLS-enabled connection in an ACL callout, while not stomping all
86 over the TLS variables available for expansion.
88 Some of these correspond to variables in globals.c; those variables will
89 be set to point to content in one of these instances, as appropriate for
90 the stage of the process lifetime.
92 Not handled here: global tls_channelbinding_b64.
95 typedef struct exim_gnutls_state {
96 gnutls_session_t session;
97 gnutls_certificate_credentials_t x509_cred;
98 gnutls_priority_t priority_cache;
99 enum peer_verify_requirement verify_requirement;
102 BOOL peer_cert_verified;
103 BOOL trigger_sni_changes;
104 BOOL have_set_peerdn;
105 const struct host_item *host;
106 gnutls_x509_crt_t peercert;
109 uschar *received_sni;
111 const uschar *tls_certificate;
112 const uschar *tls_privatekey;
113 const uschar *tls_sni; /* client send only, not received */
114 const uschar *tls_verify_certificates;
115 const uschar *tls_crl;
116 const uschar *tls_require_ciphers;
118 uschar *exp_tls_certificate;
119 uschar *exp_tls_privatekey;
120 uschar *exp_tls_verify_certificates;
122 uschar *exp_tls_require_ciphers;
123 uschar *exp_tls_ocsp_file;
124 const uschar *exp_tls_verify_cert_hostnames;
125 #ifndef DISABLE_EVENT
126 uschar *event_action;
129 tls_support *tlsp; /* set in tls_init() */
136 } exim_gnutls_state_st;
138 static const exim_gnutls_state_st exim_gnutls_state_init = {
139 NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, FALSE,
140 NULL, NULL, NULL, NULL,
141 NULL, NULL, NULL, NULL, NULL, NULL,
142 NULL, NULL, NULL, NULL, NULL, NULL, NULL,
144 #ifndef DISABLE_EVENT
151 /* Not only do we have our own APIs which don't pass around state, assuming
152 it's held in globals, GnuTLS doesn't appear to let us register callback data
153 for callbacks, or as part of the session, so we have to keep a "this is the
154 context we're currently dealing with" pointer and rely upon being
155 single-threaded to keep from processing data on an inbound TLS connection while
156 talking to another TLS connection for an outbound check. This does mean that
157 there's no way for heart-beats to be responded to, for the duration of the
159 XXX But see gnutls_session_get_ptr()
162 static exim_gnutls_state_st state_server, state_client;
164 /* dh_params are initialised once within the lifetime of a process using TLS;
165 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
166 don't want to repeat this. */
168 static gnutls_dh_params_t dh_server_params = NULL;
170 /* No idea how this value was chosen; preserving it. Default is 3600. */
172 static const int ssl_session_timeout = 200;
174 static const char * const exim_default_gnutls_priority = "NORMAL";
176 /* Guard library core initialisation */
178 static BOOL exim_gnutls_base_init_done = FALSE;
181 static BOOL gnutls_buggy_ocsp = FALSE;
185 /* ------------------------------------------------------------------------ */
188 #define MAX_HOST_LEN 255
190 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
191 the library logging; a value less than 0 disables the calls to set up logging
193 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
194 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
197 #ifndef EXIM_CLIENT_DH_MIN_BITS
198 # define EXIM_CLIENT_DH_MIN_BITS 1024
201 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
202 can ask for a bit-strength. Without that, we stick to the constant we had
204 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
205 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
208 #define exim_gnutls_err_check(Label) do { \
209 if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0)
211 #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname)
213 #if GNUTLS_VERSION_NUMBER >= 0x020c00
214 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
215 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
216 # define HAVE_GNUTLS_RND
217 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
218 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
219 * isn't available sometimes, so this needs to become a conditional
220 * compilation; the sanest way to deal with this being a problem on
221 * older OSes is to block it in the Local/Makefile with this compiler
223 # ifndef AVOID_GNUTLS_PKCS11
224 # define HAVE_GNUTLS_PKCS11
225 # endif /* AVOID_GNUTLS_PKCS11 */
231 /* ------------------------------------------------------------------------ */
232 /* Callback declarations */
234 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
235 static void exim_gnutls_logger_cb(int level, const char *message);
238 static int exim_sni_handling_cb(gnutls_session_t session);
241 static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
242 gnutls_datum_t * ocsp_response);
247 /* ------------------------------------------------------------------------ */
248 /* Static functions */
250 /*************************************************
252 *************************************************/
254 /* Called from lots of places when errors occur before actually starting to do
255 the TLS handshake, that is, while the session is still in clear. Always returns
256 DEFER for a server and FAIL for a client so that most calls can use "return
257 tls_error(...)" to do this processing and then give an appropriate return. A
258 single function is used for both server and client, because it is called from
259 some shared functions.
262 prefix text to include in the logged error
263 msg additional error string (may be NULL)
264 usually obtained from gnutls_strerror()
265 host NULL if setting up a server;
266 the connected host if setting up a client
268 Returns: OK/DEFER/FAIL
272 tls_error(const uschar *prefix, const char *msg, const host_item *host)
276 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s)%s%s",
277 host->name, host->address, prefix, msg ? ": " : "", msg ? msg : "");
282 uschar *conn_info = smtp_get_connection_info();
283 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
285 /* I'd like to get separated H= here, but too hard for now */
286 log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s",
287 conn_info, prefix, msg ? ": " : "", msg ? msg : "");
295 /*************************************************
296 * Deal with logging errors during I/O *
297 *************************************************/
299 /* We have to get the identity of the peer from saved data.
302 state the current GnuTLS exim state container
303 rc the GnuTLS error code, or 0 if it's a local error
304 when text identifying read or write
305 text local error text when ec is 0
311 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
315 if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
316 msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc),
317 US gnutls_alert_get_name(gnutls_alert_get(state->session)));
319 msg = gnutls_strerror(rc);
321 tls_error(when, msg, state->host);
327 /*************************************************
328 * Set various Exim expansion vars *
329 *************************************************/
331 #define exim_gnutls_cert_err(Label) \
334 if (rc != GNUTLS_E_SUCCESS) \
336 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
337 (Label), gnutls_strerror(rc)); \
343 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
347 rc = gnutls_x509_crt_init(crtp);
348 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
350 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
351 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
356 #undef exim_gnutls_cert_err
359 /* We set various Exim global variables from the state, once a session has
360 been established. With TLS callouts, may need to change this to stack
361 variables, or just re-call it with the server state after client callout
364 Make sure anything set here is unset in tls_getc().
368 tls_bits strength indicator
369 tls_certificate_verified bool indicator
370 tls_channelbinding_b64 for some SASL mechanisms
372 tls_peercert pointer to library internal
374 tls_sni a (UTF-8) string
375 tls_ourcert pointer to library internal
378 state the relevant exim_gnutls_state_st *
382 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
384 gnutls_cipher_algorithm_t cipher;
385 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
388 gnutls_datum_t channel;
390 tls_support * tlsp = state->tlsp;
392 tlsp->active = state->fd_out;
394 cipher = gnutls_cipher_get(state->session);
395 /* returns size in "bytes" */
396 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
398 tlsp->cipher = state->ciphersuite;
400 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
402 tlsp->certificate_verified = state->peer_cert_verified;
404 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
405 only available for use for authenticators while this TLS session is running. */
407 tls_channelbinding_b64 = NULL;
408 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
411 rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel);
413 DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc));
415 old_pool = store_pool;
416 store_pool = POOL_PERM;
417 tls_channelbinding_b64 = b64encode(channel.data, (int)channel.size);
418 store_pool = old_pool;
419 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
423 /* peercert is set in peer_status() */
424 tlsp->peerdn = state->peerdn;
425 tlsp->sni = state->received_sni;
427 /* record our certificate */
429 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
430 gnutls_x509_crt_t crt;
432 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
439 /*************************************************
440 * Setup up DH parameters *
441 *************************************************/
443 /* Generating the D-H parameters may take a long time. They only need to
444 be re-generated every so often, depending on security policy. What we do is to
445 keep these parameters in a file in the spool directory. If the file does not
446 exist, we generate them. This means that it is easy to cause a regeneration.
448 The new file is written as a temporary file and renamed, so that an incomplete
449 file is never present. If two processes both compute some new parameters, you
450 waste a bit of effort, but it doesn't seem worth messing around with locking to
453 Returns: OK/DEFER/FAIL
460 unsigned int dh_bits;
462 uschar filename_buf[PATH_MAX];
463 uschar *filename = NULL;
465 uschar *exp_tls_dhparam;
466 BOOL use_file_in_spool = FALSE;
467 BOOL use_fixed_file = FALSE;
468 host_item *host = NULL; /* dummy for macros */
470 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n");
472 rc = gnutls_dh_params_init(&dh_server_params);
473 exim_gnutls_err_check(US"gnutls_dh_params_init");
478 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam))
481 if (!exp_tls_dhparam)
483 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
484 m.data = US std_dh_prime_default();
485 m.size = Ustrlen(m.data);
487 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
488 use_file_in_spool = TRUE;
489 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
491 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
494 else if (exp_tls_dhparam[0] != '/')
496 m.data = US std_dh_prime_named(exp_tls_dhparam);
498 return tls_error(US"No standard prime named", CS exp_tls_dhparam, NULL);
499 m.size = Ustrlen(m.data);
503 use_fixed_file = TRUE;
504 filename = exp_tls_dhparam;
509 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
510 exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3");
511 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
515 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
516 /* If you change this constant, also change dh_param_fn_ext so that we can use a
517 different filename and ensure we have sufficient bits. */
518 dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL);
520 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL);
522 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
525 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
527 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
531 /* Some clients have hard-coded limits. */
532 if (dh_bits > tls_dh_max_bits)
535 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
537 dh_bits = tls_dh_max_bits;
540 if (use_file_in_spool)
542 if (!string_format(filename_buf, sizeof(filename_buf),
543 "%s/gnutls-params-%d", spool_directory, dh_bits))
544 return tls_error(US"overlong filename", NULL, NULL);
545 filename = filename_buf;
548 /* Open the cache file for reading and if successful, read it and set up the
551 fd = Uopen(filename, O_RDONLY, 0);
558 if (fstat(fd, &statbuf) < 0) /* EIO */
562 return tls_error(US"TLS cache stat failed", strerror(saved_errno), NULL);
564 if (!S_ISREG(statbuf.st_mode))
567 return tls_error(US"TLS cache not a file", NULL, NULL);
569 if (!(fp = fdopen(fd, "rb")))
573 return tls_error(US"fdopen(TLS cache stat fd) failed",
574 strerror(saved_errno), NULL);
577 m.size = statbuf.st_size;
578 if (!(m.data = malloc(m.size)))
581 return tls_error(US"malloc failed", strerror(errno), NULL);
583 if (!(sz = fread(m.data, m.size, 1, fp)))
588 return tls_error(US"fread failed", strerror(saved_errno), NULL);
592 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
594 exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3");
595 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
598 /* If the file does not exist, fall through to compute new data and cache it.
599 If there was any other opening error, it is serious. */
601 else if (errno == ENOENT)
605 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
608 return tls_error(string_open_failed(errno, "\"%s\" for reading", filename),
611 /* If ret < 0, either the cache file does not exist, or the data it contains
612 is not useful. One particular case of this is when upgrading from an older
613 release of Exim in which the data was stored in a different format. We don't
614 try to be clever and support both formats; we just regenerate new data in this
620 unsigned int dh_bits_gen = dh_bits;
622 if ((PATH_MAX - Ustrlen(filename)) < 10)
623 return tls_error(US"Filename too long to generate replacement",
626 temp_fn = string_copy(US "%s.XXXXXXX");
627 fd = mkstemp(CS temp_fn); /* modifies temp_fn */
629 return tls_error(US"Unable to open temp file", strerror(errno), NULL);
630 (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */
632 /* GnuTLS overshoots!
633 * If we ask for 2236, we might get 2237 or more.
634 * But there's no way to ask GnuTLS how many bits there really are.
635 * We can ask how many bits were used in a TLS session, but that's it!
636 * The prime itself is hidden behind too much abstraction.
637 * So we ask for less, and proceed on a wing and a prayer.
638 * First attempt, subtracted 3 for 2233 and got 2240.
640 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
642 dh_bits_gen = dh_bits - 10;
644 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
649 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
651 rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen);
652 exim_gnutls_err_check(US"gnutls_dh_params_generate2");
654 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
655 and I confirmed that a NULL call to get the size first is how the GnuTLS
656 sample apps handle this. */
660 rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
662 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
663 exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing");
665 if (!(m.data = malloc(m.size)))
666 return tls_error(US"memory allocation failed", strerror(errno), NULL);
668 /* this will return a size 1 less than the allocation size above */
669 rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
671 if (rc != GNUTLS_E_SUCCESS)
674 exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real");
676 m.size = sz; /* shrink by 1, probably */
678 sz = write_to_fd_buf(fd, m.data, (size_t) m.size);
682 return tls_error(US"TLS cache write D-H params failed",
683 strerror(errno), NULL);
686 sz = write_to_fd_buf(fd, US"\n", 1);
688 return tls_error(US"TLS cache write D-H params final newline failed",
689 strerror(errno), NULL);
693 return tls_error(US"TLS cache write close() failed",
694 strerror(errno), NULL);
696 if (Urename(temp_fn, filename) < 0)
697 return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"",
698 temp_fn, filename), strerror(errno), NULL);
700 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
703 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
710 /* Create and install a selfsigned certificate, for use in server mode */
713 tls_install_selfsign(exim_gnutls_state_st * state)
715 gnutls_x509_crt_t cert = NULL;
717 gnutls_x509_privkey_t pkey = NULL;
718 const uschar * where;
721 where = US"initialising pkey";
722 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
724 where = US"initialising cert";
725 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
727 where = US"generating pkey";
728 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
729 #ifdef SUPPORT_PARAM_TO_PK_BITS
730 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_LOW),
737 where = US"configuring cert";
739 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
740 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
741 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
742 || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */
743 || (rc = gnutls_x509_crt_set_key(cert, pkey))
745 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
746 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
747 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
748 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
749 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
750 GNUTLS_OID_X520_COMMON_NAME, 0,
751 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
755 where = US"signing cert";
756 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
758 where = US"installing selfsign cert";
760 if ((rc = gnutls_certificate_set_x509_key(state->x509_cred, &cert, 1, pkey)))
766 if (cert) gnutls_x509_crt_deinit(cert);
767 if (pkey) gnutls_x509_privkey_deinit(pkey);
771 rc = tls_error(where, gnutls_strerror(rc), NULL);
778 /*************************************************
779 * Variables re-expanded post-SNI *
780 *************************************************/
782 /* Called from both server and client code, via tls_init(), and also from
783 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
785 We can tell the two apart by state->received_sni being non-NULL in callback.
787 The callback should not call us unless state->trigger_sni_changes is true,
788 which we are responsible for setting on the first pass through.
791 state exim_gnutls_state_st *
793 Returns: OK/DEFER/FAIL
797 tls_expand_session_files(exim_gnutls_state_st *state)
801 const host_item *host = state->host; /* macro should be reconsidered? */
802 uschar *saved_tls_certificate = NULL;
803 uschar *saved_tls_privatekey = NULL;
804 uschar *saved_tls_verify_certificates = NULL;
805 uschar *saved_tls_crl = NULL;
808 /* We check for tls_sni *before* expansion. */
809 if (!host) /* server */
810 if (!state->received_sni)
812 if (state->tls_certificate &&
813 (Ustrstr(state->tls_certificate, US"tls_sni") ||
814 Ustrstr(state->tls_certificate, US"tls_in_sni") ||
815 Ustrstr(state->tls_certificate, US"tls_out_sni")
818 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
819 state->trigger_sni_changes = TRUE;
824 /* useful for debugging */
825 saved_tls_certificate = state->exp_tls_certificate;
826 saved_tls_privatekey = state->exp_tls_privatekey;
827 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
828 saved_tls_crl = state->exp_tls_crl;
831 rc = gnutls_certificate_allocate_credentials(&state->x509_cred);
832 exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials");
834 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
835 state members, assuming consistent naming; and expand_check() returns
836 false if expansion failed, unless expansion was forced to fail. */
838 /* check if we at least have a certificate, before doing expensive
841 if (!expand_check_tlsvar(tls_certificate))
844 /* certificate is mandatory in server, optional in client */
846 if ( !state->exp_tls_certificate
847 || !*state->exp_tls_certificate
850 return tls_install_selfsign(state);
852 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
854 if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey))
857 /* tls_privatekey is optional, defaulting to same file as certificate */
859 if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
861 state->tls_privatekey = state->tls_certificate;
862 state->exp_tls_privatekey = state->exp_tls_certificate;
866 if (state->exp_tls_certificate && *state->exp_tls_certificate)
868 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
869 state->exp_tls_certificate, state->exp_tls_privatekey);
871 if (state->received_sni)
872 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
873 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
876 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
880 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
883 rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
884 CS state->exp_tls_certificate, CS state->exp_tls_privatekey,
885 GNUTLS_X509_FMT_PEM);
886 exim_gnutls_err_check(
887 string_sprintf("cert/key setup: cert=%s key=%s",
888 state->exp_tls_certificate, state->exp_tls_privatekey));
889 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
890 } /* tls_certificate */
893 /* Set the OCSP stapling server info */
896 if ( !host /* server */
900 if (gnutls_buggy_ocsp)
902 DEBUG(D_tls) debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
906 if (!expand_check(tls_ocsp_file, US"tls_ocsp_file",
907 &state->exp_tls_ocsp_file))
910 /* Use the full callback method for stapling just to get observability.
911 More efficient would be to read the file once only, if it never changed
912 (due to SNI). Would need restart on file update, or watch datestamp. */
914 gnutls_certificate_set_ocsp_status_request_function(state->x509_cred,
915 server_ocsp_stapling_cb, state->exp_tls_ocsp_file);
917 DEBUG(D_tls) debug_printf("OCSP response file = %s\n", state->exp_tls_ocsp_file);
923 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
924 provided. Experiment shows that, if the certificate file is empty, an unhelpful
925 error message is provided. However, if we just refrain from setting anything up
926 in that case, certificate verification fails, which seems to be the correct
929 if (state->tls_verify_certificates && *state->tls_verify_certificates)
931 if (!expand_check_tlsvar(tls_verify_certificates))
933 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
934 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
935 state->exp_tls_verify_certificates = NULL;
937 if (state->tls_crl && *state->tls_crl)
938 if (!expand_check_tlsvar(tls_crl))
941 if (!(state->exp_tls_verify_certificates &&
942 *state->exp_tls_verify_certificates))
945 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
946 /* With no tls_verify_certificates, we ignore tls_crl too */
953 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
957 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
958 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
959 cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
963 if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
965 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
966 "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
971 #ifndef SUPPORT_CA_DIR
972 /* The test suite passes in /dev/null; we could check for that path explicitly,
973 but who knows if someone has some weird FIFO which always dumps some certs, or
974 other weirdness. The thing we really want to check is that it's not a
975 directory, since while OpenSSL supports that, GnuTLS does not.
976 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
977 if (S_ISDIR(statbuf.st_mode))
980 debug_printf("verify certificates path is a dir: \"%s\"\n",
981 state->exp_tls_verify_certificates);
982 log_write(0, LOG_MAIN|LOG_PANIC,
983 "tls_verify_certificates \"%s\" is a directory",
984 state->exp_tls_verify_certificates);
989 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
990 state->exp_tls_verify_certificates, statbuf.st_size);
992 if (statbuf.st_size == 0)
995 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1001 #ifdef SUPPORT_CA_DIR
1002 (statbuf.st_mode & S_IFMT) == S_IFDIR
1004 gnutls_certificate_set_x509_trust_dir(state->x509_cred,
1005 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
1008 gnutls_certificate_set_x509_trust_file(state->x509_cred,
1009 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
1015 exim_gnutls_err_check(US"setting certificate trust");
1017 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count);
1019 if (state->tls_crl && *state->tls_crl &&
1020 state->exp_tls_crl && *state->exp_tls_crl)
1022 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
1023 cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
1024 CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM);
1028 exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file");
1030 DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
1039 /*************************************************
1040 * Set X.509 state variables *
1041 *************************************************/
1043 /* In GnuTLS, the registered cert/key are not replaced by a later
1044 set of a cert/key, so for SNI support we need a whole new x509_cred
1045 structure. Which means various other non-re-expanded pieces of state
1046 need to be re-set in the new struct, so the setting logic is pulled
1050 state exim_gnutls_state_st *
1052 Returns: OK/DEFER/FAIL
1056 tls_set_remaining_x509(exim_gnutls_state_st *state)
1059 const host_item *host = state->host; /* macro should be reconsidered? */
1061 /* Create D-H parameters, or read them from the cache file. This function does
1062 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1063 client-side params. */
1067 if (!dh_server_params)
1069 rc = init_server_dh();
1070 if (rc != OK) return rc;
1072 gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
1075 /* Link the credentials to the session. */
1077 rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred);
1078 exim_gnutls_err_check(US"gnutls_credentials_set");
1083 /*************************************************
1084 * Initialize for GnuTLS *
1085 *************************************************/
1088 #ifndef DISABLE_OCSP
1091 tls_is_buggy_ocsp(void)
1094 uschar maj, mid, mic;
1096 s = CUS gnutls_check_version(NULL);
1100 while (*s && *s != '.') s++;
1101 mid = atoi(CCS ++s);
1108 while (*s && *s != '.') s++;
1109 mic = atoi(CCS ++s);
1110 return mic <= (mid == 3 ? 16 : 3);
1119 /* Called from both server and client code. In the case of a server, errors
1120 before actual TLS negotiation return DEFER.
1123 host connected host, if client; NULL if server
1124 certificate certificate file
1125 privatekey private key file
1126 sni TLS SNI to send, sometimes when client; else NULL
1129 require_ciphers tls_require_ciphers setting
1130 caller_state returned state-info structure
1132 Returns: OK/DEFER/FAIL
1137 const host_item *host,
1138 const uschar *certificate,
1139 const uschar *privatekey,
1143 const uschar *require_ciphers,
1144 exim_gnutls_state_st **caller_state)
1146 exim_gnutls_state_st *state;
1151 BOOL want_default_priorities;
1153 if (!exim_gnutls_base_init_done)
1155 DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
1157 #ifdef HAVE_GNUTLS_PKCS11
1158 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1159 which loads modules from a config file, which sounds good and may be wanted
1160 by some sysadmin, but also means in common configurations that GNOME keyring
1161 environment variables are used and so breaks for users calling mailq.
1162 To prevent this, we init PKCS11 first, which is the documented approach. */
1163 if (!gnutls_allow_auto_pkcs11)
1165 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
1166 exim_gnutls_err_check(US"gnutls_pkcs11_init");
1170 rc = gnutls_global_init();
1171 exim_gnutls_err_check(US"gnutls_global_init");
1173 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1176 gnutls_global_set_log_function(exim_gnutls_logger_cb);
1177 /* arbitrarily chosen level; bump upto 9 for more */
1178 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
1182 #ifndef DISABLE_OCSP
1183 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
1184 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
1187 exim_gnutls_base_init_done = TRUE;
1192 state = &state_client;
1193 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1194 state->tlsp = &tls_out;
1195 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
1196 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
1200 state = &state_server;
1201 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1202 state->tlsp = &tls_in;
1203 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
1204 rc = gnutls_init(&state->session, GNUTLS_SERVER);
1206 exim_gnutls_err_check(US"gnutls_init");
1210 state->tls_certificate = certificate;
1211 state->tls_privatekey = privatekey;
1212 state->tls_require_ciphers = require_ciphers;
1213 state->tls_sni = sni;
1214 state->tls_verify_certificates = cas;
1215 state->tls_crl = crl;
1217 /* This handles the variables that might get re-expanded after TLS SNI;
1218 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1221 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1222 rc = tls_expand_session_files(state);
1223 if (rc != OK) return rc;
1225 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1226 requires a new structure afterwards. */
1228 rc = tls_set_remaining_x509(state);
1229 if (rc != OK) return rc;
1231 /* set SNI in client, only */
1234 if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni))
1236 if (state->tlsp->sni && *state->tlsp->sni)
1239 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
1240 sz = Ustrlen(state->tlsp->sni);
1241 rc = gnutls_server_name_set(state->session,
1242 GNUTLS_NAME_DNS, state->tlsp->sni, sz);
1243 exim_gnutls_err_check(US"gnutls_server_name_set");
1246 else if (state->tls_sni)
1247 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
1248 "have an SNI set for a client [%s]\n", state->tls_sni);
1250 /* This is the priority string support,
1251 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1252 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1253 This was backwards incompatible, but means Exim no longer needs to track
1254 all algorithms and provide string forms for them. */
1256 want_default_priorities = TRUE;
1258 if (state->tls_require_ciphers && *state->tls_require_ciphers)
1260 if (!expand_check_tlsvar(tls_require_ciphers))
1262 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
1264 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n",
1265 state->exp_tls_require_ciphers);
1267 rc = gnutls_priority_init(&state->priority_cache,
1268 CS state->exp_tls_require_ciphers, &errpos);
1269 want_default_priorities = FALSE;
1270 p = state->exp_tls_require_ciphers;
1273 if (want_default_priorities)
1276 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n",
1277 exim_default_gnutls_priority);
1278 rc = gnutls_priority_init(&state->priority_cache,
1279 exim_default_gnutls_priority, &errpos);
1280 p = US exim_default_gnutls_priority;
1283 exim_gnutls_err_check(string_sprintf(
1284 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1285 p, errpos - CS p, errpos));
1287 rc = gnutls_priority_set(state->session, state->priority_cache);
1288 exim_gnutls_err_check(US"gnutls_priority_set");
1290 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
1292 /* Reduce security in favour of increased compatibility, if the admin
1293 decides to make that trade-off. */
1294 if (gnutls_compat_mode)
1296 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1297 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
1298 gnutls_session_enable_compatibility_mode(state->session);
1300 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1304 *caller_state = state;
1310 /*************************************************
1311 * Extract peer information *
1312 *************************************************/
1314 /* Called from both server and client code.
1315 Only this is allowed to set state->peerdn and state->have_set_peerdn
1316 and we use that to detect double-calls.
1318 NOTE: the state blocks last while the TLS connection is up, which is fine
1319 for logging in the server side, but for the client side, we log after teardown
1320 in src/deliver.c. While the session is up, we can twist about states and
1321 repoint tls_* globals, but those variables used for logging or other variable
1322 expansion that happens _after_ delivery need to have a longer life-time.
1324 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1325 doing this more than once per generation of a state context. We set them in
1326 the state context, and repoint tls_* to them. After the state goes away, the
1327 tls_* copies of the pointers remain valid and client delivery logging is happy.
1329 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1333 state exim_gnutls_state_st *
1335 Returns: OK/DEFER/FAIL
1339 peer_status(exim_gnutls_state_st *state)
1341 uschar cipherbuf[256];
1342 const gnutls_datum_t *cert_list;
1344 unsigned int cert_list_size = 0;
1345 gnutls_protocol_t protocol;
1346 gnutls_cipher_algorithm_t cipher;
1347 gnutls_kx_algorithm_t kx;
1348 gnutls_mac_algorithm_t mac;
1349 gnutls_certificate_type_t ct;
1350 gnutls_x509_crt_t crt;
1354 if (state->have_set_peerdn)
1356 state->have_set_peerdn = TRUE;
1358 state->peerdn = NULL;
1361 cipher = gnutls_cipher_get(state->session);
1362 protocol = gnutls_protocol_get_version(state->session);
1363 mac = gnutls_mac_get(state->session);
1364 kx = gnutls_kx_get(state->session);
1366 string_format(cipherbuf, sizeof(cipherbuf),
1368 gnutls_protocol_get_name(protocol),
1369 gnutls_cipher_suite_get_name(kx, cipher, mac),
1370 (int) gnutls_cipher_get_key_size(cipher) * 8);
1372 /* I don't see a way that spaces could occur, in the current GnuTLS
1373 code base, but it was a concern in the old code and perhaps older GnuTLS
1374 releases did return "TLS 1.0"; play it safe, just in case. */
1375 for (p = cipherbuf; *p != '\0'; ++p)
1378 old_pool = store_pool;
1379 store_pool = POOL_PERM;
1380 state->ciphersuite = string_copy(cipherbuf);
1381 store_pool = old_pool;
1382 state->tlsp->cipher = state->ciphersuite;
1385 cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size);
1387 if (cert_list == NULL || cert_list_size == 0)
1389 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1390 cert_list, cert_list_size);
1391 if (state->verify_requirement >= VERIFY_REQUIRED)
1392 return tls_error(US"certificate verification failed",
1393 "no certificate received from peer", state->host);
1397 ct = gnutls_certificate_type_get(state->session);
1398 if (ct != GNUTLS_CRT_X509)
1400 const char *ctn = gnutls_certificate_type_get_name(ct);
1402 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
1403 if (state->verify_requirement >= VERIFY_REQUIRED)
1404 return tls_error(US"certificate verification not possible, unhandled type",
1409 #define exim_gnutls_peer_err(Label) \
1411 if (rc != GNUTLS_E_SUCCESS) \
1413 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1414 (Label), gnutls_strerror(rc)); \
1415 if (state->verify_requirement >= VERIFY_REQUIRED) \
1416 return tls_error((Label), gnutls_strerror(rc), state->host); \
1421 rc = import_cert(&cert_list[0], &crt);
1422 exim_gnutls_peer_err(US"cert 0");
1424 state->tlsp->peercert = state->peercert = crt;
1427 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
1428 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
1430 exim_gnutls_peer_err(US"getting size for cert DN failed");
1431 return FAIL; /* should not happen */
1433 dn_buf = store_get_perm(sz);
1434 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
1435 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1437 state->peerdn = dn_buf;
1440 #undef exim_gnutls_peer_err
1446 /*************************************************
1447 * Verify peer certificate *
1448 *************************************************/
1450 /* Called from both server and client code.
1451 *Should* be using a callback registered with
1452 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1453 the peer information, but that's too new for some OSes.
1456 state exim_gnutls_state_st *
1457 error where to put an error message
1460 FALSE if the session should be rejected
1461 TRUE if the cert is okay or we just don't care
1465 verify_certificate(exim_gnutls_state_st *state, const char **error)
1468 unsigned int verify;
1472 if ((rc = peer_status(state)) != OK)
1474 verify = GNUTLS_CERT_INVALID;
1475 *error = "certificate not supplied";
1478 rc = gnutls_certificate_verify_peers2(state->session, &verify);
1480 /* Handle the result of verification. INVALID seems to be set as well
1481 as REVOKED, but leave the test for both. */
1484 verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)
1487 state->peer_cert_verified = FALSE;
1489 *error = verify & GNUTLS_CERT_REVOKED
1490 ? "certificate revoked" : "certificate invalid";
1493 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1494 *error, state->peerdn ? state->peerdn : US"<unset>");
1496 if (state->verify_requirement >= VERIFY_REQUIRED)
1498 gnutls_alert_send(state->session,
1499 GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
1503 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1508 if (state->exp_tls_verify_cert_hostnames)
1511 const uschar * list = state->exp_tls_verify_cert_hostnames;
1513 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1514 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert, CS name))
1519 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1520 if (state->verify_requirement >= VERIFY_REQUIRED)
1522 gnutls_alert_send(state->session,
1523 GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
1529 state->peer_cert_verified = TRUE;
1530 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1531 state->peerdn ? state->peerdn : US"<unset>");
1534 state->tlsp->peerdn = state->peerdn;
1542 /* ------------------------------------------------------------------------ */
1545 /* Logging function which can be registered with
1546 * gnutls_global_set_log_function()
1547 * gnutls_global_set_log_level() 0..9
1549 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1551 exim_gnutls_logger_cb(int level, const char *message)
1553 size_t len = strlen(message);
1556 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
1559 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
1560 message[len-1] == '\n' ? "" : "\n");
1565 /* Called after client hello, should handle SNI work.
1566 This will always set tls_sni (state->received_sni) if available,
1567 and may trigger presenting different certificates,
1568 if state->trigger_sni_changes is TRUE.
1570 Should be registered with
1571 gnutls_handshake_set_post_client_hello_function()
1573 "This callback must return 0 on success or a gnutls error code to terminate the
1576 For inability to get SNI information, we return 0.
1577 We only return non-zero if re-setup failed.
1578 Only used for server-side TLS.
1582 exim_sni_handling_cb(gnutls_session_t session)
1584 char sni_name[MAX_HOST_LEN];
1585 size_t data_len = MAX_HOST_LEN;
1586 exim_gnutls_state_st *state = &state_server;
1587 unsigned int sni_type;
1590 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
1591 if (rc != GNUTLS_E_SUCCESS)
1594 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
1595 debug_printf("TLS: no SNI presented in handshake.\n");
1597 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
1598 gnutls_strerror(rc), rc);
1603 if (sni_type != GNUTLS_NAME_DNS)
1605 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
1609 /* We now have a UTF-8 string in sni_name */
1610 old_pool = store_pool;
1611 store_pool = POOL_PERM;
1612 state->received_sni = string_copyn(US sni_name, data_len);
1613 store_pool = old_pool;
1615 /* We set this one now so that variable expansions below will work */
1616 state->tlsp->sni = state->received_sni;
1618 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
1619 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
1621 if (!state->trigger_sni_changes)
1624 rc = tls_expand_session_files(state);
1627 /* If the setup of certs/etc failed before handshake, TLS would not have
1628 been offered. The best we can do now is abort. */
1629 return GNUTLS_E_APPLICATION_ERROR_MIN;
1632 rc = tls_set_remaining_x509(state);
1633 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
1640 #ifndef DISABLE_OCSP
1643 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
1644 gnutls_datum_t * ocsp_response)
1648 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
1650 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
1652 tls_in.ocsp = OCSP_NOT_RESP;
1653 return GNUTLS_E_NO_CERTIFICATE_STATUS;
1656 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1663 #ifndef DISABLE_EVENT
1665 We use this callback to get observability and detail-level control
1666 for an exim TLS connection (either direction), raising a tls:cert event
1667 for each cert in the chain presented by the peer. Any event
1668 can deny verification.
1670 Return 0 for the handshake to continue or non-zero to terminate.
1674 verify_cb(gnutls_session_t session)
1676 const gnutls_datum_t * cert_list;
1677 unsigned int cert_list_size = 0;
1678 gnutls_x509_crt_t crt;
1681 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
1683 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
1685 while (cert_list_size--)
1687 rc = import_cert(&cert_list[cert_list_size], &crt);
1688 if (rc != GNUTLS_E_SUCCESS)
1690 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
1691 cert_list_size, gnutls_strerror(rc));
1695 state->tlsp->peercert = crt;
1696 if ((yield = event_raise(state->event_action,
1697 US"tls:cert", string_sprintf("%d", cert_list_size))))
1699 log_write(0, LOG_MAIN,
1700 "SSL verify denied by event-action: depth=%d: %s",
1701 cert_list_size, yield);
1702 return 1; /* reject */
1704 state->tlsp->peercert = NULL;
1714 /* ------------------------------------------------------------------------ */
1715 /* Exported functions */
1720 /*************************************************
1721 * Start a TLS session in a server *
1722 *************************************************/
1724 /* This is called when Exim is running as a server, after having received
1725 the STARTTLS command. It must respond to that command, and then negotiate
1729 require_ciphers list of allowed ciphers or NULL
1731 Returns: OK on success
1732 DEFER for errors before the start of the negotiation
1733 FAIL for errors during the negotation; the server can't
1738 tls_server_start(const uschar *require_ciphers)
1742 exim_gnutls_state_st *state = NULL;
1744 /* Check for previous activation */
1745 if (tls_in.active >= 0)
1747 tls_error(US"STARTTLS received after TLS started", "", NULL);
1748 smtp_printf("554 Already in TLS\r\n");
1752 /* Initialize the library. If it fails, it will already have logged the error
1753 and sent an SMTP response. */
1755 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
1757 rc = tls_init(NULL, tls_certificate, tls_privatekey,
1758 NULL, tls_verify_certificates, tls_crl,
1759 require_ciphers, &state);
1760 if (rc != OK) return rc;
1762 /* If this is a host for which certificate verification is mandatory or
1763 optional, set up appropriately. */
1765 if (verify_check_host(&tls_verify_hosts) == OK)
1768 debug_printf("TLS: a client certificate will be required.\n");
1769 state->verify_requirement = VERIFY_REQUIRED;
1770 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
1772 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1775 debug_printf("TLS: a client certificate will be requested but not required.\n");
1776 state->verify_requirement = VERIFY_OPTIONAL;
1777 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
1782 debug_printf("TLS: a client certificate will not be requested.\n");
1783 state->verify_requirement = VERIFY_NONE;
1784 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
1787 #ifndef DISABLE_EVENT
1790 state->event_action = event_action;
1791 gnutls_session_set_ptr(state->session, state);
1792 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
1796 /* Register SNI handling; always, even if not in tls_certificate, so that the
1797 expansion variable $tls_sni is always available. */
1799 gnutls_handshake_set_post_client_hello_function(state->session,
1800 exim_sni_handling_cb);
1802 /* Set context and tell client to go ahead, except in the case of TLS startup
1803 on connection, where outputting anything now upsets the clients and tends to
1804 make them disconnect. We need to have an explicit fflush() here, to force out
1805 the response. Other smtp_printf() calls do not need it, because in non-TLS
1806 mode, the fflush() happens when smtp_getc() is called. */
1808 if (!state->tlsp->on_connect)
1810 smtp_printf("220 TLS go ahead\r\n");
1814 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1815 that the GnuTLS library doesn't. */
1817 gnutls_transport_set_ptr2(state->session,
1818 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
1819 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
1820 state->fd_in = fileno(smtp_in);
1821 state->fd_out = fileno(smtp_out);
1823 sigalrm_seen = FALSE;
1824 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1826 rc = gnutls_handshake(state->session);
1827 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
1830 if (rc != GNUTLS_E_SUCCESS)
1832 /* It seems that, except in the case of a timeout, we have to close the
1833 connection right here; otherwise if the other end is running OpenSSL it hangs
1834 until the server times out. */
1837 tls_error(US"gnutls_handshake", "timed out", NULL);
1840 tls_error(US"gnutls_handshake", gnutls_strerror(rc), NULL);
1841 gnutls_alert_send_appropriate(state->session, rc);
1843 shutdown(fileno(smtp_out), SHUT_WR);
1844 for (rc = 1024; fgetc(smtp_in) != EOF && rc > 0; ) rc--; /* drain skt */
1845 (void)fclose(smtp_out);
1846 (void)fclose(smtp_in);
1847 smtp_out = smtp_in = NULL;
1853 DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
1855 /* Verify after the fact */
1857 if ( state->verify_requirement != VERIFY_NONE
1858 && !verify_certificate(state, &error))
1860 if (state->verify_requirement != VERIFY_OPTIONAL)
1862 tls_error(US"certificate verification failed", error, NULL);
1866 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
1870 /* Figure out peer DN, and if authenticated, etc. */
1872 if ((rc = peer_status(state)) != OK) return rc;
1874 /* Sets various Exim expansion variables; always safe within server */
1876 extract_exim_vars_from_tls_state(state);
1878 /* TLS has been set up. Adjust the input functions to read via TLS,
1879 and initialize appropriately. */
1881 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1883 receive_getc = tls_getc;
1884 receive_get_cache = tls_get_cache;
1885 receive_ungetc = tls_ungetc;
1886 receive_feof = tls_feof;
1887 receive_ferror = tls_ferror;
1888 receive_smtp_buffered = tls_smtp_buffered;
1897 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
1898 smtp_transport_options_block * ob)
1900 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1902 state->exp_tls_verify_cert_hostnames =
1904 string_domain_utf8_to_alabel(host->name, NULL);
1909 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
1910 state->exp_tls_verify_cert_hostnames);
1915 /*************************************************
1916 * Start a TLS session in a client *
1917 *************************************************/
1919 /* Called from the smtp transport after STARTTLS has been accepted.
1922 fd the fd of the connection
1923 host connected host (for messages)
1924 addr the first address (not used)
1925 tb transport (always smtp)
1927 Returns: OK/DEFER/FAIL (because using common functions),
1928 but for a client, DEFER and FAIL have the same meaning
1932 tls_client_start(int fd, host_item *host,
1933 address_item *addr ARG_UNUSED,
1934 transport_instance *tb
1935 #ifdef EXPERIMENTAL_DANE
1936 , dns_answer * unused_tlsa_dnsa
1940 smtp_transport_options_block *ob =
1941 (smtp_transport_options_block *)tb->options_block;
1944 exim_gnutls_state_st *state = NULL;
1945 #ifndef DISABLE_OCSP
1947 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
1948 BOOL request_ocsp = require_ocsp ? TRUE
1949 : verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1952 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd);
1954 if ((rc = tls_init(host, ob->tls_certificate, ob->tls_privatekey,
1955 ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl,
1956 ob->tls_require_ciphers, &state)) != OK)
1960 int dh_min_bits = ob->tls_dh_min_bits;
1961 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
1964 debug_printf("WARNING: tls_dh_min_bits far too low,"
1965 " clamping %d up to %d\n",
1966 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
1967 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
1970 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
1971 " acceptable bits to %d\n",
1973 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
1976 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
1977 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
1978 the specified host patterns if one of them is defined */
1980 if ( ( state->exp_tls_verify_certificates
1981 && !ob->tls_verify_hosts
1982 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
1984 || verify_check_given_host(&ob->tls_verify_hosts, host) == OK
1987 tls_client_setup_hostname_checks(host, state, ob);
1989 debug_printf("TLS: server certificate verification required.\n");
1990 state->verify_requirement = VERIFY_REQUIRED;
1991 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
1993 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1995 tls_client_setup_hostname_checks(host, state, ob);
1997 debug_printf("TLS: server certificate verification optional.\n");
1998 state->verify_requirement = VERIFY_OPTIONAL;
1999 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2004 debug_printf("TLS: server certificate verification not required.\n");
2005 state->verify_requirement = VERIFY_NONE;
2006 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2009 #ifndef DISABLE_OCSP
2010 /* supported since GnuTLS 3.1.3 */
2013 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
2014 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
2015 NULL, 0, NULL)) != OK)
2016 return tls_error(US"cert-status-req",
2017 gnutls_strerror(rc), state->host);
2018 tls_out.ocsp = OCSP_NOT_RESP;
2022 #ifndef DISABLE_EVENT
2023 if (tb->event_action)
2025 state->event_action = tb->event_action;
2026 gnutls_session_set_ptr(state->session, state);
2027 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2031 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) fd);
2035 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
2036 /* There doesn't seem to be a built-in timeout on connection. */
2038 sigalrm_seen = FALSE;
2039 alarm(ob->command_timeout);
2042 rc = gnutls_handshake(state->session);
2043 } while ((rc == GNUTLS_E_AGAIN) ||
2044 (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen));
2047 if (rc != GNUTLS_E_SUCCESS)
2050 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
2051 return tls_error(US"gnutls_handshake", "timed out", state->host);
2054 return tls_error(US"gnutls_handshake", gnutls_strerror(rc), state->host);
2056 DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
2060 if (state->verify_requirement != VERIFY_NONE &&
2061 !verify_certificate(state, &error))
2062 return tls_error(US"certificate verification failed", error, state->host);
2064 #ifndef DISABLE_OCSP
2069 gnutls_datum_t stapling;
2070 gnutls_ocsp_resp_t resp;
2071 gnutls_datum_t printed;
2072 if ( (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0
2073 && (rc= gnutls_ocsp_resp_init(&resp)) == 0
2074 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
2075 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0
2078 debug_printf("%.4096s", printed.data);
2079 gnutls_free(printed.data);
2082 (void) tls_error(US"ocsp decode", gnutls_strerror(rc), state->host);
2085 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
2087 tls_out.ocsp = OCSP_FAILED;
2088 return tls_error(US"certificate status check failed", NULL, state->host);
2090 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
2091 tls_out.ocsp = OCSP_VFIED;
2095 /* Figure out peer DN, and if authenticated, etc. */
2097 if ((rc = peer_status(state)) != OK)
2100 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2102 extract_exim_vars_from_tls_state(state);
2110 /*************************************************
2111 * Close down a TLS session *
2112 *************************************************/
2114 /* This is also called from within a delivery subprocess forked from the
2115 daemon, to shut down the TLS library, without actually doing a shutdown (which
2116 would tamper with the TLS session in the parent process).
2118 Arguments: TRUE if gnutls_bye is to be called
2123 tls_close(BOOL is_server, BOOL shutdown)
2125 exim_gnutls_state_st *state = is_server ? &state_server : &state_client;
2127 if (!state->tlsp || state->tlsp->active < 0) return; /* TLS was not active */
2131 DEBUG(D_tls) debug_printf("tls_close() from '%s': shutting down TLS\n");
2132 gnutls_bye(state->session, GNUTLS_SHUT_WR);
2135 gnutls_deinit(state->session);
2137 state->tlsp->active = -1;
2138 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2140 if ((state_server.session == NULL) && (state_client.session == NULL))
2142 gnutls_global_deinit();
2143 exim_gnutls_base_init_done = FALSE;
2151 /*************************************************
2152 * TLS version of getc *
2153 *************************************************/
2155 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2156 it refills the buffer via the GnuTLS reading function.
2157 Only used by the server-side TLS.
2159 This feeds DKIM and should be used for all message-body reads.
2162 Returns: the next character or EOF
2168 exim_gnutls_state_st *state = &state_server;
2169 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
2173 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2174 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
2176 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2177 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
2178 ssl_xfer_buffer_size);
2181 /* Timeouts do not get this far; see command_timeout_handler().
2182 A zero-byte return appears to mean that the TLS session has been
2183 closed down, not that the socket itself has been closed down. Revert to
2184 non-TLS handling. */
2188 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
2189 state->xfer_error = 1;
2193 else if (inbytes == 0)
2195 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
2197 receive_getc = smtp_getc;
2198 receive_get_cache = smtp_get_cache;
2199 receive_ungetc = smtp_ungetc;
2200 receive_feof = smtp_feof;
2201 receive_ferror = smtp_ferror;
2202 receive_smtp_buffered = smtp_buffered;
2204 gnutls_deinit(state->session);
2205 state->session = NULL;
2206 state->tlsp->active = -1;
2207 state->tlsp->bits = 0;
2208 state->tlsp->certificate_verified = FALSE;
2209 tls_channelbinding_b64 = NULL;
2210 state->tlsp->cipher = NULL;
2211 state->tlsp->peercert = NULL;
2212 state->tlsp->peerdn = NULL;
2217 /* Handle genuine errors */
2219 else if (inbytes < 0)
2221 record_io_error(state, (int) inbytes, US"recv", NULL);
2222 state->xfer_error = 1;
2225 #ifndef DISABLE_DKIM
2226 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
2228 state->xfer_buffer_hwm = (int) inbytes;
2229 state->xfer_buffer_lwm = 0;
2232 /* Something in the buffer; return next uschar */
2234 return state->xfer_buffer[state->xfer_buffer_lwm++];
2240 #ifndef DISABLE_DKIM
2241 exim_gnutls_state_st * state = &state_server;
2242 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
2244 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
2251 /*************************************************
2252 * Read bytes from TLS channel *
2253 *************************************************/
2255 /* This does not feed DKIM, so if the caller uses this for reading message body,
2256 then the caller must feed DKIM.
2262 Returns: the number of bytes read
2263 -1 after a failed read
2267 tls_read(BOOL is_server, uschar *buff, size_t len)
2269 exim_gnutls_state_st *state = is_server ? &state_server : &state_client;
2275 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
2277 debug_printf("*** PROBABLY A BUG *** " \
2278 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
2279 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
2282 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n",
2283 state->session, buff, len);
2285 inbytes = gnutls_record_recv(state->session, buff, len);
2286 if (inbytes > 0) return inbytes;
2289 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
2291 else record_io_error(state, (int)inbytes, US"recv", NULL);
2299 /*************************************************
2300 * Write bytes down TLS channel *
2301 *************************************************/
2305 is_server channel specifier
2309 Returns: the number of bytes after a successful write,
2310 -1 after a failed write
2314 tls_write(BOOL is_server, const uschar *buff, size_t len)
2318 exim_gnutls_state_st *state = is_server ? &state_server : &state_client;
2320 DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left);
2323 DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n",
2325 outbytes = gnutls_record_send(state->session, buff, left);
2327 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
2330 record_io_error(state, outbytes, US"send", NULL);
2335 record_io_error(state, 0, US"send", US"TLS channel closed on write");
2346 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
2357 /*************************************************
2358 * Random number generation *
2359 *************************************************/
2361 /* Pseudo-random number generation. The result is not expected to be
2362 cryptographically strong but not so weak that someone will shoot themselves
2363 in the foot using it as a nonce in input in some email header scheme or
2364 whatever weirdness they'll twist this into. The result should handle fork()
2365 and avoid repeating sequences. OpenSSL handles that for us.
2369 Returns a random number in range [0, max-1]
2372 #ifdef HAVE_GNUTLS_RND
2374 vaguely_random_number(int max)
2379 uschar smallbuf[sizeof(r)];
2384 needed_len = sizeof(r);
2385 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2386 * asked for a number less than 10. */
2387 for (r = max, i = 0; r; ++i)
2393 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
2396 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
2397 return vaguely_random_number_fallback(max);
2400 for (p = smallbuf; needed_len; --needed_len, ++p)
2406 /* We don't particularly care about weighted results; if someone wants
2407 * smooth distribution and cares enough then they should submit a patch then. */
2410 #else /* HAVE_GNUTLS_RND */
2412 vaguely_random_number(int max)
2414 return vaguely_random_number_fallback(max);
2416 #endif /* HAVE_GNUTLS_RND */
2421 /*************************************************
2422 * Let tls_require_ciphers be checked at startup *
2423 *************************************************/
2425 /* The tls_require_ciphers option, if set, must be something which the
2428 Returns: NULL on success, or error message
2432 tls_validate_require_cipher(void)
2435 uschar *expciphers = NULL;
2436 gnutls_priority_t priority_cache;
2439 #define validate_check_rc(Label) do { \
2440 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
2441 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
2442 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
2444 if (exim_gnutls_base_init_done)
2445 log_write(0, LOG_MAIN|LOG_PANIC,
2446 "already initialised GnuTLS, Exim developer bug");
2448 #ifdef HAVE_GNUTLS_PKCS11
2449 if (!gnutls_allow_auto_pkcs11)
2451 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
2452 validate_check_rc(US"gnutls_pkcs11_init");
2455 rc = gnutls_global_init();
2456 validate_check_rc(US"gnutls_global_init()");
2457 exim_gnutls_base_init_done = TRUE;
2459 if (!(tls_require_ciphers && *tls_require_ciphers))
2460 return_deinit(NULL);
2462 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2463 return_deinit(US"failed to expand tls_require_ciphers");
2465 if (!(expciphers && *expciphers))
2466 return_deinit(NULL);
2469 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2471 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
2472 validate_check_rc(string_sprintf(
2473 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
2474 expciphers, errpos - CS expciphers, errpos));
2476 #undef return_deinit
2477 #undef validate_check_rc
2478 gnutls_global_deinit();
2486 /*************************************************
2487 * Report the library versions. *
2488 *************************************************/
2490 /* See a description in tls-openssl.c for an explanation of why this exists.
2492 Arguments: a FILE* to print the results to
2497 tls_version_report(FILE *f)
2499 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
2502 gnutls_check_version(NULL));
2507 /* End of tls-gnu.c */