1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Copyright (c) Phil Pennock 2012 */
11 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
12 one of the available supported implementations. This file is #included into
13 tls.c when USE_GNUTLS has been set.
15 The code herein is a revamp of GnuTLS integration using the current APIs; the
16 original tls-gnu.c was based on a patch which was contributed by Nikos
17 Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as
20 APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
21 which is not widely deployed by OS vendors. Will note issues below, which may
22 assist in updating the code in the future. Another sources of hints is
23 mod_gnutls for Apache (SNI callback registration and handling).
25 Keeping client and server variables more split than before and is currently
26 the norm, in anticipation of TLS in ACL callouts.
28 I wanted to switch to gnutls_certificate_set_verify_function() so that
29 certificate rejection could happen during handshake where it belongs, rather
30 than being dropped afterwards, but that was introduced in 2.10.0 and Debian
31 (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
33 (I wasn't looking for libraries quite that old, when updating to get rid of
34 compiler warnings of deprecated APIs. If it turns out that a lot of the rest
35 require current GnuTLS, then we'll drop support for the ancient libraries).
38 #include <gnutls/gnutls.h>
39 /* needed for cert checks in verification and DN extraction: */
40 #include <gnutls/x509.h>
41 /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
42 #include <gnutls/crypto.h>
44 /* needed to disable PKCS11 autoload unless requested */
45 #if GNUTLS_VERSION_NUMBER >= 0x020c00
46 # include <gnutls/pkcs11.h>
47 # define SUPPORT_PARAM_TO_PK_BITS
49 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
50 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
53 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
54 # warning "GnuTLS library version too old; tls:cert event unsupported"
55 # define DISABLE_EVENT
57 #if GNUTLS_VERSION_NUMBER >= 0x030000
58 # define SUPPORT_SELFSIGN /* Uncertain what version is first usable but 2.12.23 is not */
60 #if GNUTLS_VERSION_NUMBER >= 0x030306
61 # define SUPPORT_CA_DIR
63 # undef SUPPORT_CA_DIR
65 #if GNUTLS_VERSION_NUMBER >= 0x030014
66 # define SUPPORT_SYSDEFAULT_CABUNDLE
68 #if GNUTLS_VERSION_NUMBER >= 0x030104
69 # define GNUTLS_CERT_VFY_STATUS_PRINT
71 #if GNUTLS_VERSION_NUMBER >= 0x030109
74 #if GNUTLS_VERSION_NUMBER >= 0x03010a
75 # define SUPPORT_GNUTLS_SESS_DESC
77 #if GNUTLS_VERSION_NUMBER >= 0x030300
78 # define GNUTLS_AUTO_GLOBAL_INIT
79 # define GNUTLS_AUTO_PKCS11_MANUAL
81 #if (GNUTLS_VERSION_NUMBER >= 0x030404) \
82 || (GNUTLS_VERSION_NUMBER >= 0x030311) && (GNUTLS_VERSION_NUMBER & 0xffff00 == 0x030300)
84 # define EXIM_HAVE_OCSP
87 #if GNUTLS_VERSION_NUMBER >= 0x030500
88 # define SUPPORT_GNUTLS_KEYLOG
90 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
91 # define SUPPORT_SRV_OCSP_STACK
93 #if GNUTLS_VERSION_NUMBER >= 0x030600
94 # define GNUTLS_AUTO_DHPARAMS
96 #if GNUTLS_VERSION_NUMBER >= 0x030603
97 # define EXIM_HAVE_TLS1_3
98 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
99 # define GNUTLS_OCSP_STATUS_REQUEST_GET2
103 # if GNUTLS_VERSION_NUMBER >= 0x030000
104 # define DANESSL_USAGE_DANE_TA 2
105 # define DANESSL_USAGE_DANE_EE 3
107 # error GnuTLS version too early for DANE
109 # if GNUTLS_VERSION_NUMBER < 0x999999
110 # define GNUTLS_BROKEN_DANE_VALIDATION
114 #ifndef DISABLE_TLS_RESUME
115 # if GNUTLS_VERSION_NUMBER >= 0x030603
116 # define EXIM_HAVE_TLS_RESUME
118 # warning "GnuTLS library version too old; resumption unsupported"
123 # include <gnutls/ocsp.h>
126 # include <gnutls/dane.h>
129 #include "tls-cipher-stdname.c"
136 # ifndef DISABLE_TLS_RESUME
137 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
139 # ifdef EXIM_HAVE_TLS1_3
140 builtin_macro_create(US"_HAVE_TLS1_3");
142 # ifdef EXIM_HAVE_OCSP
143 builtin_macro_create(US"_HAVE_TLS_OCSP");
145 # ifdef SUPPORT_SRV_OCSP_STACK
146 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
148 #ifdef EXIM_HAVE_INOTIFY
149 builtin_macro_create(US"_HAVE_TLS_CA_CACHE");
158 gnutls_global_set_audit_log_function()
161 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
164 /* Local static variables for GnuTLS */
166 /* Values for verify_requirement */
168 enum peer_verify_requirement
169 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
171 /* This holds most state for server or client; with this, we can set up an
172 outbound TLS-enabled connection in an ACL callout, while not stomping all
173 over the TLS variables available for expansion.
175 Some of these correspond to variables in globals.c; those variables will
176 be set to point to content in one of these instances, as appropriate for
177 the stage of the process lifetime.
179 Not handled here: global tlsp->tls_channelbinding.
182 typedef struct exim_gnutls_state {
183 gnutls_session_t session;
185 exim_tlslib_state lib_state;
186 #define x509_cred libdata0
187 #define pri_cache libdata1
189 enum peer_verify_requirement verify_requirement;
193 BOOL peer_cert_verified:1;
194 BOOL peer_dane_verified:1;
195 BOOL trigger_sni_changes:1;
196 BOOL have_set_peerdn:1;
197 BOOL xfer_eof:1; /*XXX never gets set! */
203 const struct host_item *host; /* NULL if server */
204 gnutls_x509_crt_t peercert;
207 uschar *received_sni;
209 const uschar *tls_certificate;
210 const uschar *tls_privatekey;
211 const uschar *tls_sni; /* client send only, not received */
212 const uschar *tls_verify_certificates;
213 const uschar *tls_crl;
214 const uschar *tls_require_ciphers;
216 uschar *exp_tls_certificate;
217 uschar *exp_tls_privatekey;
218 uschar *exp_tls_verify_certificates;
220 uschar *exp_tls_require_ciphers;
221 const uschar *exp_tls_verify_cert_hostnames;
222 #ifndef DISABLE_EVENT
223 uschar *event_action;
226 char * const * dane_data;
227 const int * dane_data_len;
230 tls_support *tlsp; /* set in tls_init() */
235 } exim_gnutls_state_st;
237 static const exim_gnutls_state_st exim_gnutls_state_init = {
238 /* all elements not explicitly intialised here get 0/NULL/FALSE */
243 /* Not only do we have our own APIs which don't pass around state, assuming
244 it's held in globals, GnuTLS doesn't appear to let us register callback data
245 for callbacks, or as part of the session, so we have to keep a "this is the
246 context we're currently dealing with" pointer and rely upon being
247 single-threaded to keep from processing data on an inbound TLS connection while
248 talking to another TLS connection for an outbound check. This does mean that
249 there's no way for heart-beats to be responded to, for the duration of the
251 XXX But see gnutls_session_get_ptr()
254 static exim_gnutls_state_st state_server = {
255 /* all elements not explicitly intialised here get 0/NULL/FALSE */
260 #ifndef GNUTLS_AUTO_DHPARAMS
261 /* dh_params are initialised once within the lifetime of a process using TLS;
262 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
263 don't want to repeat this. */
265 static gnutls_dh_params_t dh_server_params = NULL;
268 static int ssl_session_timeout = 7200; /* Two hours */
270 static const uschar * const exim_default_gnutls_priority = US"NORMAL";
272 /* Guard library core initialisation */
274 static BOOL exim_gnutls_base_init_done = FALSE;
277 static BOOL gnutls_buggy_ocsp = FALSE;
278 static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
281 #ifdef EXIM_HAVE_TLS_RESUME
282 static gnutls_datum_t server_sessticket_key;
285 /* ------------------------------------------------------------------------ */
288 #define MAX_HOST_LEN 255
290 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
291 the library logging; a value less than 0 disables the calls to set up logging
292 callbacks. GNuTLS also looks for an environment variable - except not for
293 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
294 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
295 but the env var must be added to /etc/sudoers too. */
296 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
297 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
300 #ifndef EXIM_CLIENT_DH_MIN_BITS
301 # define EXIM_CLIENT_DH_MIN_BITS 1024
304 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
305 can ask for a bit-strength. Without that, we stick to the constant we had
307 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
308 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
311 #define Expand_check_tlsvar(Varname, errstr) \
312 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
314 #if GNUTLS_VERSION_NUMBER >= 0x020c00
315 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
316 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
317 # define HAVE_GNUTLS_RND
318 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
319 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
320 * isn't available sometimes, so this needs to become a conditional
321 * compilation; the sanest way to deal with this being a problem on
322 * older OSes is to block it in the Local/Makefile with this compiler
324 # ifndef AVOID_GNUTLS_PKCS11
325 # define HAVE_GNUTLS_PKCS11
326 # endif /* AVOID_GNUTLS_PKCS11 */
332 /* ------------------------------------------------------------------------ */
333 /* Callback declarations */
335 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
336 static void exim_gnutls_logger_cb(int level, const char *message);
339 static int exim_sni_handling_cb(gnutls_session_t session);
341 #ifdef EXIM_HAVE_TLS_RESUME
343 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
344 unsigned incoming, const gnutls_datum_t * msg);
348 /* ------------------------------------------------------------------------ */
354 tls_is_buggy_ocsp(void)
357 uschar maj, mid, mic;
359 s = CUS gnutls_check_version(NULL);
363 while (*s && *s != '.') s++;
371 while (*s && *s != '.') s++;
373 return mic <= (mid == 3 ? 16 : 3);
385 DEBUG(D_tls) debug_printf("GnuTLS global init required\n");
387 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
388 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
389 which loads modules from a config file, which sounds good and may be wanted
390 by some sysadmin, but also means in common configurations that GNOME keyring
391 environment variables are used and so breaks for users calling mailq.
392 To prevent this, we init PKCS11 first, which is the documented approach. */
394 if (!gnutls_allow_auto_pkcs11)
395 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
396 return tls_error_gnu(US"gnutls_pkcs11_init", rc, host, errstr);
399 #ifndef GNUTLS_AUTO_GLOBAL_INIT
400 if ((rc = gnutls_global_init()))
401 return tls_error_gnu(US"gnutls_global_init", rc, host, errstr);
404 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
407 gnutls_global_set_log_function(exim_gnutls_logger_cb);
408 /* arbitrarily chosen level; bump up to 9 for more */
409 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
414 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
415 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
418 exim_gnutls_base_init_done = TRUE;
423 /* Daemon-call before each connection. Nothing to do for GnuTLS. */
426 tls_per_lib_daemon_tick(void)
430 /* Daemon one-time initialisation */
433 tls_per_lib_daemon_init(void)
435 static BOOL once = FALSE;
437 if (!exim_gnutls_base_init_done)
444 #ifdef EXIM_HAVE_TLS_RESUME
445 /* We are dependent on the GnuTLS implementation of the Session Ticket
446 encryption; both the strength and the key rotation period. We hope that
447 the strength at least matches that of the ciphersuite (but GnuTLS does not
450 gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
451 if (f.running_in_test_harness) ssl_session_timeout = 6;
454 tls_daemon_creds_reload();
458 /* ------------------------------------------------------------------------ */
459 /* Static functions */
461 /*************************************************
463 *************************************************/
465 /* Called from lots of places when errors occur before actually starting to do
466 the TLS handshake, that is, while the session is still in clear. Always returns
467 DEFER for a server and FAIL for a client so that most calls can use "return
468 tls_error(...)" to do this processing and then give an appropriate return. A
469 single function is used for both server and client, because it is called from
470 some shared functions.
473 prefix text to include in the logged error
474 msg additional error string (may be NULL)
475 usually obtained from gnutls_strerror()
476 host NULL if setting up a server;
477 the connected host if setting up a client
478 errstr pointer to returned error string
480 Returns: OK/DEFER/FAIL
484 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
488 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
489 return host ? FAIL : DEFER;
494 tls_error_gnu(const uschar *prefix, int err, const host_item *host,
497 return tls_error(prefix, US gnutls_strerror(err), host, errstr);
501 tls_error_sys(const uschar *prefix, int err, const host_item *host,
504 return tls_error(prefix, US strerror(err), host, errstr);
508 /*************************************************
509 * Deal with logging errors during I/O *
510 *************************************************/
512 /* We have to get the identity of the peer from saved data.
515 state the current GnuTLS exim state container
516 rc the GnuTLS error code, or 0 if it's a local error
517 when text identifying read or write
518 text local error text when rc is 0
524 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
529 msg = rc == GNUTLS_E_FATAL_ALERT_RECEIVED
530 ? string_sprintf("A TLS fatal alert has been received: %s",
531 US gnutls_alert_get_name(gnutls_alert_get(state->session)))
532 #ifdef GNUTLS_E_PREMATURE_TERMINATION
533 : rc == GNUTLS_E_PREMATURE_TERMINATION && errno
534 ? string_sprintf("%s: syscall: %s", US gnutls_strerror(rc), strerror(errno))
536 : US gnutls_strerror(rc);
538 (void) tls_error(when, msg, state->host, &errstr);
541 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
542 state->host->name, state->host->address, errstr);
545 uschar * conn_info = smtp_get_connection_info();
546 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
547 /* I'd like to get separated H= here, but too hard for now */
548 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
555 /*************************************************
556 * Set various Exim expansion vars *
557 *************************************************/
559 #define exim_gnutls_cert_err(Label) \
562 if (rc != GNUTLS_E_SUCCESS) \
564 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
565 (Label), gnutls_strerror(rc)); \
571 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
575 rc = gnutls_x509_crt_init(crtp);
576 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
578 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
579 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
584 #undef exim_gnutls_cert_err
587 /* We set various Exim global variables from the state, once a session has
588 been established. With TLS callouts, may need to change this to stack
589 variables, or just re-call it with the server state after client callout
592 Make sure anything set here is unset in tls_getc().
596 tls_bits strength indicator
597 tls_certificate_verified bool indicator
598 tls_channelbinding for some SASL mechanisms
601 tls_peercert pointer to library internal
603 tls_sni a (UTF-8) string
604 tls_ourcert pointer to library internal
607 state the relevant exim_gnutls_state_st *
611 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
613 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
616 gnutls_datum_t channel;
618 tls_support * tlsp = state->tlsp;
620 tlsp->active.sock = state->fd_out;
621 tlsp->active.tls_ctx = state;
623 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
625 tlsp->certificate_verified = state->peer_cert_verified;
627 tlsp->dane_verified = state->peer_dane_verified;
630 /* note that tls_channelbinding is not saved to the spool file, since it's
631 only available for use for authenticators while this TLS session is running. */
633 tlsp->channelbinding = NULL;
634 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
637 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
638 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
641 /* Declare the taintedness of the binding info. On server, untainted; on
642 client, tainted - being the Finish msg from the server. */
644 old_pool = store_pool;
645 store_pool = POOL_PERM;
646 tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
648 store_pool = old_pool;
649 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
653 /* peercert is set in peer_status() */
654 tlsp->peerdn = state->peerdn;
656 /* do not corrupt sni sent by client; record sni rxd by server */
658 tlsp->sni = state->received_sni;
660 /* record our certificate */
662 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
663 gnutls_x509_crt_t crt;
665 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
672 #ifndef GNUTLS_AUTO_DHPARAMS
673 /*************************************************
674 * Setup up DH parameters *
675 *************************************************/
677 /* Generating the D-H parameters may take a long time. They only need to
678 be re-generated every so often, depending on security policy. What we do is to
679 keep these parameters in a file in the spool directory. If the file does not
680 exist, we generate them. This means that it is easy to cause a regeneration.
682 The new file is written as a temporary file and renamed, so that an incomplete
683 file is never present. If two processes both compute some new parameters, you
684 waste a bit of effort, but it doesn't seem worth messing around with locking to
687 Returns: OK/DEFER/FAIL
691 init_server_dh(uschar ** errstr)
694 unsigned int dh_bits;
695 gnutls_datum_t m = {.data = NULL, .size = 0};
696 uschar filename_buf[PATH_MAX];
697 uschar *filename = NULL;
699 uschar *exp_tls_dhparam;
700 BOOL use_file_in_spool = FALSE;
701 host_item *host = NULL; /* dummy for macros */
703 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
705 if ((rc = gnutls_dh_params_init(&dh_server_params)))
706 return tls_error_gnu(US"gnutls_dh_params_init", rc, host, errstr);
708 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
711 if (!exp_tls_dhparam)
713 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
714 m.data = US std_dh_prime_default();
715 m.size = Ustrlen(m.data);
717 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
718 use_file_in_spool = TRUE;
719 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
721 DEBUG(D_tls) debug_printf("Requested no DH parameters\n");
724 else if (exp_tls_dhparam[0] != '/')
726 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
727 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
728 m.size = Ustrlen(m.data);
731 filename = exp_tls_dhparam;
735 if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
736 return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
737 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
741 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
742 /* If you change this constant, also change dh_param_fn_ext so that we can use a
743 different filename and ensure we have sufficient bits. */
745 if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
746 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
748 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits\n",
751 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
753 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits\n",
757 /* Some clients have hard-coded limits. */
758 if (dh_bits > tls_dh_max_bits)
761 debug_printf("tls_dh_max_bits clamping override, using %d bits instead\n",
763 dh_bits = tls_dh_max_bits;
766 if (use_file_in_spool)
768 if (!string_format(filename_buf, sizeof(filename_buf),
769 "%s/gnutls-params-%d", spool_directory, dh_bits))
770 return tls_error(US"overlong filename", NULL, NULL, errstr);
771 filename = filename_buf;
774 /* Open the cache file for reading and if successful, read it and set up the
777 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
783 if (fstat(fd, &statbuf) < 0) /* EIO */
787 return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
789 if (!S_ISREG(statbuf.st_mode))
792 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
794 if (!(fp = fdopen(fd, "rb")))
798 return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
799 saved_errno, NULL, errstr);
802 m.size = statbuf.st_size;
803 if (!(m.data = store_malloc(m.size)))
806 return tls_error_sys(US"malloc failed", errno, NULL, errstr);
808 if (!(sz = fread(m.data, m.size, 1, fp)))
813 return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
817 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
820 return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
821 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
824 /* If the file does not exist, fall through to compute new data and cache it.
825 If there was any other opening error, it is serious. */
827 else if (errno == ENOENT)
831 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
834 return tls_error(string_open_failed("\"%s\" for reading", filename),
837 /* If ret < 0, either the cache file does not exist, or the data it contains
838 is not useful. One particular case of this is when upgrading from an older
839 release of Exim in which the data was stored in a different format. We don't
840 try to be clever and support both formats; we just regenerate new data in this
846 unsigned int dh_bits_gen = dh_bits;
848 if ((PATH_MAX - Ustrlen(filename)) < 10)
849 return tls_error(US"Filename too long to generate replacement",
850 filename, NULL, errstr);
852 temp_fn = string_copy(US"%s.XXXXXXX");
853 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
854 return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
855 (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
857 /* GnuTLS overshoots! If we ask for 2236, we might get 2237 or more. But
858 there's no way to ask GnuTLS how many bits there really are. We can ask
859 how many bits were used in a TLS session, but that's it! The prime itself
860 is hidden behind too much abstraction. So we ask for less, and proceed on
861 a wing and a prayer. First attempt, subtracted 3 for 2233 and got 2240. */
863 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
865 dh_bits_gen = dh_bits - 10;
867 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
872 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
874 if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
875 return tls_error_gnu(US"gnutls_dh_params_generate2", rc, host, errstr);
877 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
878 and I confirmed that a NULL call to get the size first is how the GnuTLS
879 sample apps handle this. */
883 if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
884 GNUTLS_X509_FMT_PEM, m.data, &sz))
885 && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
886 return tls_error_gnu(US"gnutls_dh_params_export_pkcs3(NULL) sizing",
889 if (!(m.data = store_malloc(m.size)))
890 return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
892 /* this will return a size 1 less than the allocation size above */
893 if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
897 return tls_error_gnu(US"gnutls_dh_params_export_pkcs3() real", rc, host, errstr);
899 m.size = sz; /* shrink by 1, probably */
901 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
904 return tls_error_sys(US"TLS cache write D-H params failed",
905 errno, NULL, errstr);
908 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
909 return tls_error_sys(US"TLS cache write D-H params final newline failed",
910 errno, NULL, errstr);
912 if ((rc = close(fd)))
913 return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
915 if (Urename(temp_fn, filename) < 0)
916 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
917 temp_fn, filename), errno, NULL, errstr);
919 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
922 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
930 /* Create and install a selfsigned certificate, for use in server mode */
933 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
935 gnutls_x509_crt_t cert = NULL;
937 gnutls_x509_privkey_t pkey = NULL;
938 const uschar * where;
941 #ifndef SUPPORT_SELFSIGN
942 where = US"library too old";
943 rc = GNUTLS_E_NO_CERTIFICATE_FOUND;
947 where = US"initialising pkey";
948 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
950 where = US"initialising cert";
951 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
953 where = US"generating pkey"; /* Hangs on 2.12.23 */
954 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
955 #ifdef SUPPORT_PARAM_TO_PK_BITS
956 # ifndef GNUTLS_SEC_PARAM_MEDIUM
957 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
959 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
966 where = US"configuring cert";
968 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
969 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
970 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
971 || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */
972 || (rc = gnutls_x509_crt_set_key(cert, pkey))
974 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
975 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
976 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
977 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
978 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
979 GNUTLS_OID_X520_COMMON_NAME, 0,
980 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
984 where = US"signing cert";
985 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
987 where = US"installing selfsign cert";
989 if ((rc = gnutls_certificate_set_x509_key(state->lib_state.x509_cred,
996 if (cert) gnutls_x509_crt_deinit(cert);
997 if (pkey) gnutls_x509_privkey_deinit(pkey);
1001 rc = tls_error_gnu(where, rc, NULL, errstr);
1008 /* Add certificate and key, from files.
1011 Zero or negative: good. Negate value for certificate index if < 0.
1012 Greater than zero: FAIL or DEFER code.
1016 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
1017 const uschar * certfile, const uschar * keyfile, uschar ** errstr)
1019 int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
1020 CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
1022 return tls_error_gnu(
1023 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
1029 #if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1030 /* Load an OCSP proof from file for sending by the server. Called
1031 on getting a status-request handshake message, for earlier versions
1035 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
1036 gnutls_datum_t * ocsp_response)
1039 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
1041 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
1043 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
1045 tls_in.ocsp = OCSP_NOT_RESP;
1046 return GNUTLS_E_NO_CERTIFICATE_STATUS;
1049 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1055 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1056 /* Make a note that we saw a status-request */
1058 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
1059 const unsigned char *data, unsigned size)
1061 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1062 if (tls_id == 5) /* status_request */
1064 DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
1065 tls_in.ocsp = OCSP_NOT_RESP;
1070 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
1072 tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
1073 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1075 /* Call fn for each extension seen. 3.6.3 onwards */
1076 return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
1077 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
1081 /* Make a note that we saw a status-response */
1083 tls_server_servercerts_ext(void * ctx, unsigned tls_id,
1084 const unsigned char *data, unsigned size)
1086 /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
1087 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1088 if (FALSE && tls_id == 5) /* status_request */
1090 DEBUG(D_tls) debug_printf("Seen status_request extension\n");
1091 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1092 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1097 /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
1099 tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
1100 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1102 /* Call fn for each extension seen. 3.6.3 onwards */
1105 return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
1110 /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
1111 "Handshake Protocol: Certificate" record.
1112 So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
1114 This is different to tls1.2 - where it is a separate record (wireshark term) / handshake message (gnutls term).
1117 #if defined(EXIM_HAVE_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1118 /* Callback for certificate-status, on server. We sent stapled OCSP. */
1120 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
1121 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1123 DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
1124 #ifdef SUPPORT_SRV_OCSP_STACK
1125 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1126 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1128 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1133 /* Callback for handshake messages, on server */
1135 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
1136 unsigned incoming, const gnutls_datum_t * msg)
1138 /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
1141 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1142 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
1143 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
1144 case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
1145 return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
1147 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
1148 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
1149 # ifdef EXIM_HAVE_TLS_RESUME
1150 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
1151 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
1160 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1162 tls_server_testharness_ocsp_fiddle(void)
1164 extern char ** environ;
1165 if (environ) for (uschar ** p = USS environ; *p; p++)
1166 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1168 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
1169 exim_testharness_disable_ocsp_validity_check = TRUE;
1174 /**************************************************
1175 * One-time init credentials for server and client *
1176 **************************************************/
1179 creds_basic_init(gnutls_certificate_credentials_t x509_cred, BOOL server)
1181 #ifdef SUPPORT_SRV_OCSP_STACK
1182 gnutls_certificate_set_flags(x509_cred, GNUTLS_CERTIFICATE_API_V2);
1184 # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1185 if (server && tls_ocsp_file)
1187 if (f.running_in_test_harness)
1188 tls_server_testharness_ocsp_fiddle();
1190 if (exim_testharness_disable_ocsp_validity_check)
1191 gnutls_certificate_set_flags(x509_cred,
1192 GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
1197 debug_printf("TLS: basic cred init, %s\n", server ? "server" : "client");
1201 creds_load_server_certs(exim_gnutls_state_st * state, const uschar * cert,
1202 const uschar * pkey, const uschar * ocsp, uschar ** errstr)
1204 const uschar * clist = cert;
1205 const uschar * klist = pkey;
1206 const uschar * olist;
1207 int csep = 0, ksep = 0, osep = 0, cnt = 0, rc;
1208 uschar * cfile, * kfile, * ofile;
1209 #ifndef DISABLE_OCSP
1210 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1211 gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
1214 if (!expand_check(ocsp, US"tls_ocsp_file", &ofile, errstr))
1219 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1221 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1222 return tls_error(US"cert/key setup: out of keys", NULL, NULL, errstr);
1223 else if ((rc = tls_add_certfile(state, NULL, cfile, kfile, errstr)) > 0)
1227 int gnutls_cert_index = -rc;
1228 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
1229 gnutls_cert_index, cfile);
1231 #ifndef DISABLE_OCSP
1234 /* Set the OCSP stapling server info */
1235 if (gnutls_buggy_ocsp)
1238 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1240 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1242 DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n",
1243 gnutls_cert_index, ofile);
1244 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1245 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1247 ocsp_fmt = GNUTLS_X509_FMT_PEM;
1250 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1252 ocsp_fmt = GNUTLS_X509_FMT_DER;
1256 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1257 state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
1259 return tls_error_gnu(
1260 US"gnutls_certificate_set_ocsp_status_request_file2",
1263 debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
1265 /* Arrange callbacks for OCSP request observability */
1268 gnutls_handshake_set_hook_function(state->session,
1269 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1271 state->lib_state.ocsp_hook = TRUE;
1275 # if defined(SUPPORT_SRV_OCSP_STACK)
1276 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1277 state->lib_state.x509_cred, gnutls_cert_index,
1278 server_ocsp_stapling_cb, ofile)))
1279 return tls_error_gnu(
1280 US"gnutls_certificate_set_ocsp_status_request_function2",
1288 debug_printf("oops; multiple OCSP files not supported\n");
1291 gnutls_certificate_set_ocsp_status_request_function(
1292 state->lib_state.x509_cred, server_ocsp_stapling_cb, ofile);
1294 # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
1297 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1299 #endif /* DISABLE_OCSP */
1305 creds_load_client_certs(exim_gnutls_state_st * state, const host_item * host,
1306 const uschar * cert, const uschar * pkey, uschar ** errstr)
1308 int rc = tls_add_certfile(state, host, cert, pkey, errstr);
1309 if (rc > 0) return rc;
1310 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1315 creds_load_cabundle(exim_gnutls_state_st * state, const uschar * bundle,
1316 const host_item * host, uschar ** errstr)
1319 struct stat statbuf;
1321 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1322 if (Ustrcmp(bundle, "system") == 0 || Ustrncmp(bundle, "system,", 7) == 0)
1323 cert_count = gnutls_certificate_set_x509_system_trust(state->lib_state.x509_cred);
1327 if (Ustat(bundle, &statbuf) < 0)
1329 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' "
1330 "(tls_verify_certificates): %s", bundle, strerror(errno));
1334 #ifndef SUPPORT_CA_DIR
1335 /* The test suite passes in /dev/null; we could check for that path explicitly,
1336 but who knows if someone has some weird FIFO which always dumps some certs, or
1337 other weirdness. The thing we really want to check is that it's not a
1338 directory, since while OpenSSL supports that, GnuTLS does not.
1339 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1340 if (S_ISDIR(statbuf.st_mode))
1342 log_write(0, LOG_MAIN|LOG_PANIC,
1343 "tls_verify_certificates \"%s\" is a directory", bundle);
1348 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1349 bundle, statbuf.st_size);
1351 if (statbuf.st_size == 0)
1354 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1360 #ifdef SUPPORT_CA_DIR
1361 (statbuf.st_mode & S_IFMT) == S_IFDIR
1363 gnutls_certificate_set_x509_trust_dir(state->lib_state.x509_cred,
1364 CS bundle, GNUTLS_X509_FMT_PEM)
1367 gnutls_certificate_set_x509_trust_file(state->lib_state.x509_cred,
1368 CS bundle, GNUTLS_X509_FMT_PEM);
1370 #ifdef SUPPORT_CA_DIR
1371 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1372 when using the directory-of-certs config model. */
1374 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1376 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1378 state->lib_state.ca_rdn_emulate = TRUE;
1383 return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr);
1385 debug_printf("Added %d certificate authorities\n", cert_count);
1392 creds_load_crl(exim_gnutls_state_st * state, const uschar * crl, uschar ** errstr)
1395 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
1396 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
1397 CS crl, GNUTLS_X509_FMT_PEM)) < 0)
1398 return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file",
1399 cert_count, state->host, errstr);
1401 DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
1407 creds_load_pristring(exim_gnutls_state_st * state, const uschar * p,
1408 const char ** errpos)
1412 p = exim_default_gnutls_priority;
1414 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1416 return gnutls_priority_init( (gnutls_priority_t *) &state->lib_state.pri_cache,
1421 tls_server_creds_init(void)
1423 uschar * dummy_errstr;
1425 state_server.lib_state = null_tls_preload;
1426 if (gnutls_certificate_allocate_credentials(
1427 (gnutls_certificate_credentials_t *) &state_server.lib_state.x509_cred))
1429 state_server.lib_state.x509_cred = NULL;
1432 creds_basic_init(state_server.lib_state.x509_cred, TRUE);
1434 #ifdef EXIM_HAVE_INOTIFY
1435 /* If tls_certificate has any $ indicating expansions, it is not good.
1436 If tls_privatekey is set but has $, not good. Likewise for tls_ocsp_file.
1437 If all good (and tls_certificate set), load the cert(s). Do not try
1438 to handle selfsign generation for now (tls_certificate null/empty;
1439 XXX will want to do that later though) due to the lifetime/expiry issue. */
1441 if ( opt_set_and_noexpand(tls_certificate)
1442 && opt_unset_or_noexpand(tls_privatekey)
1443 && opt_unset_or_noexpand(tls_ocsp_file))
1445 /* Set watches on the filenames. The implementation does de-duplication
1446 so we can just blindly do them all.
1449 if ( tls_set_watch(tls_certificate, TRUE)
1450 && tls_set_watch(tls_privatekey, TRUE)
1451 && tls_set_watch(tls_ocsp_file, TRUE)
1454 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1455 if (creds_load_server_certs(&state_server, tls_certificate,
1456 tls_privatekey && *tls_privatekey ? tls_privatekey : tls_certificate,
1457 tls_ocsp_file, &dummy_errstr) == 0)
1458 state_server.lib_state.conn_certs = TRUE;
1462 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1464 /* If tls_verify_certificates is non-empty and has no $, load CAs */
1466 if (opt_set_and_noexpand(tls_verify_certificates))
1468 if (tls_set_watch(tls_verify_certificates, FALSE))
1470 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1471 if (creds_load_cabundle(&state_server, tls_verify_certificates,
1472 NULL, &dummy_errstr) != OK)
1474 state_server.lib_state.cabundle = TRUE;
1476 /* If CAs loaded and tls_crl is non-empty and has no $, load it */
1478 if (opt_set_and_noexpand(tls_crl))
1480 if (tls_set_watch(tls_crl, FALSE))
1482 DEBUG(D_tls) debug_printf("TLS: preloading CRL for server\n");
1483 if (creds_load_crl(&state_server, tls_crl, &dummy_errstr) != OK)
1485 state_server.lib_state.crl = TRUE;
1489 DEBUG(D_tls) debug_printf("TLS: not preloading CRL for server\n");
1493 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1494 #endif /* EXIM_HAVE_INOTIFY */
1496 /* If tls_require_ciphers is non-empty and has no $, load the
1497 ciphers priority cache. If unset, load with the default.
1498 (server-only as the client one depends on non/DANE) */
1500 if (!tls_require_ciphers || opt_set_and_noexpand(tls_require_ciphers))
1502 const char * dummy_errpos;
1503 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server: %s\n",
1504 tls_require_ciphers);
1505 if ( creds_load_pristring(&state_server, tls_require_ciphers, &dummy_errpos)
1507 state_server.lib_state.pri_string = TRUE;
1510 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1514 /* Preload whatever creds are static, onto a transport. The client can then
1515 just copy the pointer as it starts up. */
1518 tls_client_creds_init(transport_instance * t, BOOL watch)
1520 smtp_transport_options_block * ob = t->options_block;
1521 exim_gnutls_state_st tpt_dummy_state;
1522 host_item * dummy_host = (host_item *)1;
1523 uschar * dummy_errstr;
1525 if (!exim_gnutls_base_init_done)
1528 ob->tls_preload = null_tls_preload;
1529 if (gnutls_certificate_allocate_credentials(
1530 (struct gnutls_certificate_credentials_st **)&ob->tls_preload.x509_cred))
1532 ob->tls_preload.x509_cred = NULL;
1535 creds_basic_init(ob->tls_preload.x509_cred, FALSE);
1537 tpt_dummy_state.session = NULL;
1538 tpt_dummy_state.lib_state = ob->tls_preload;
1540 #ifdef EXIM_HAVE_INOTIFY
1541 if ( opt_set_and_noexpand(ob->tls_certificate)
1542 && opt_unset_or_noexpand(ob->tls_privatekey))
1545 || ( tls_set_watch(ob->tls_certificate, FALSE)
1546 && tls_set_watch(ob->tls_privatekey, FALSE)
1549 const uschar * pkey = ob->tls_privatekey;
1552 debug_printf("TLS: preloading client certs for transport '%s'\n", t->name);
1554 /* The state->lib_state.x509_cred is used for the certs load, and is the sole
1555 structure element used. So we can set up a dummy. The hoat arg only
1556 selects a retcode in case of fail, so any value */
1558 if (creds_load_client_certs(&tpt_dummy_state, dummy_host,
1559 ob->tls_certificate, pkey ? pkey : ob->tls_certificate,
1560 &dummy_errstr) == OK)
1561 ob->tls_preload.conn_certs = TRUE;
1566 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1568 if (opt_set_and_noexpand(ob->tls_verify_certificates))
1570 if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
1573 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1574 if (creds_load_cabundle(&tpt_dummy_state, ob->tls_verify_certificates,
1575 dummy_host, &dummy_errstr) != OK)
1577 ob->tls_preload.cabundle = TRUE;
1579 if (opt_set_and_noexpand(ob->tls_crl))
1581 if (!watch || tls_set_watch(ob->tls_crl, FALSE))
1583 DEBUG(D_tls) debug_printf("TLS: preloading CRL for transport '%s'\n", t->name);
1584 if (creds_load_crl(&tpt_dummy_state, ob->tls_crl, &dummy_errstr) != OK)
1586 ob->tls_preload.crl = TRUE;
1590 DEBUG(D_tls) debug_printf("TLS: not preloading CRL, for transport '%s'\n", t->name);
1595 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1597 /* We do not preload tls_require_ciphers to to the transport as it implicitly
1598 depends on DANE or plain usage. */
1604 #ifdef EXIM_HAVE_INOTIFY
1605 /* Invalidate the creds cached, by dropping the current ones.
1606 Call when we notice one of the source files has changed. */
1609 tls_server_creds_invalidate(void)
1611 if (state_server.lib_state.pri_cache)
1612 gnutls_priority_deinit(state_server.lib_state.pri_cache);
1613 state_server.lib_state.pri_cache = NULL;
1615 if (state_server.lib_state.x509_cred)
1616 gnutls_certificate_free_credentials(state_server.lib_state.x509_cred);
1617 state_server.lib_state = null_tls_preload;
1622 tls_client_creds_invalidate(transport_instance * t)
1624 smtp_transport_options_block * ob = t->options_block;
1625 if (ob->tls_preload.x509_cred)
1626 gnutls_certificate_free_credentials(ob->tls_preload.x509_cred);
1627 ob->tls_preload = null_tls_preload;
1632 /*************************************************
1633 * Variables re-expanded post-SNI *
1634 *************************************************/
1636 /* Called from both server and client code, via tls_init(), and also from
1637 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
1639 We can tell the two apart by state->received_sni being non-NULL in callback.
1641 The callback should not call us unless state->trigger_sni_changes is true,
1642 which we are responsible for setting on the first pass through.
1645 state exim_gnutls_state_st *
1646 errstr error string pointer
1648 Returns: OK/DEFER/FAIL
1652 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
1655 const host_item *host = state->host; /* macro should be reconsidered? */
1656 const uschar *saved_tls_certificate = NULL;
1657 const uschar *saved_tls_privatekey = NULL;
1658 const uschar *saved_tls_verify_certificates = NULL;
1659 const uschar *saved_tls_crl = NULL;
1662 /* We check for tls_sni *before* expansion. */
1663 if (!host) /* server */
1664 if (!state->received_sni)
1666 if ( state->tls_certificate
1667 && ( Ustrstr(state->tls_certificate, US"tls_sni")
1668 || Ustrstr(state->tls_certificate, US"tls_in_sni")
1669 || Ustrstr(state->tls_certificate, US"tls_out_sni")
1672 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI\n");
1673 state->trigger_sni_changes = TRUE;
1676 else /* SNI callback case */
1678 /* useful for debugging */
1679 saved_tls_certificate = state->exp_tls_certificate;
1680 saved_tls_privatekey = state->exp_tls_privatekey;
1681 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1682 saved_tls_crl = state->exp_tls_crl;
1685 if (!state->lib_state.x509_cred)
1687 if ((rc = gnutls_certificate_allocate_credentials(
1688 (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))
1689 return tls_error_gnu(US"gnutls_certificate_allocate_credentials",
1691 creds_basic_init(state->lib_state.x509_cred, !host);
1695 /* remember: Expand_check_tlsvar() is expand_check() but fiddling with
1696 state members, assuming consistent naming; and expand_check() returns
1697 false if expansion failed, unless expansion was forced to fail. */
1699 /* check if we at least have a certificate, before doing expensive
1702 if (!state->lib_state.conn_certs)
1704 if (!Expand_check_tlsvar(tls_certificate, errstr))
1707 /* certificate is mandatory in server, optional in client */
1709 if ( !state->exp_tls_certificate
1710 || !*state->exp_tls_certificate
1713 return tls_install_selfsign(state, errstr);
1715 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1717 if (state->tls_privatekey && !Expand_check_tlsvar(tls_privatekey, errstr))
1720 /* tls_privatekey is optional, defaulting to same file as certificate */
1722 if (!state->tls_privatekey || !*state->tls_privatekey)
1724 state->tls_privatekey = state->tls_certificate;
1725 state->exp_tls_privatekey = state->exp_tls_certificate;
1728 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1731 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1732 state->exp_tls_certificate, state->exp_tls_privatekey);
1734 if (state->received_sni)
1735 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1736 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1739 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1740 load = FALSE; /* avoid re-loading the same certs */
1742 else /* unload the pre-SNI certs before loading new ones */
1744 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair\n");
1745 gnutls_certificate_free_keys(state->lib_state.x509_cred);
1750 ? creds_load_client_certs(state, host, state->exp_tls_certificate,
1751 state->exp_tls_privatekey, errstr)
1752 : creds_load_server_certs(state, state->exp_tls_certificate,
1753 state->exp_tls_privatekey, tls_ocsp_file, errstr)
1760 debug_printf("%s certs were preloaded\n", host ? "client" : "server");
1762 if (!state->tls_privatekey) state->tls_privatekey = state->tls_certificate;
1763 state->exp_tls_certificate = US state->tls_certificate;
1764 state->exp_tls_privatekey = US state->tls_privatekey;
1766 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1767 if (state->lib_state.ocsp_hook)
1768 gnutls_handshake_set_hook_function(state->session,
1769 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1774 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1775 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1776 error message is provided. However, if we just refrain from setting anything up
1777 in that case, certificate verification fails, which seems to be the correct
1780 if (!state->lib_state.cabundle)
1782 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1784 if (!Expand_check_tlsvar(tls_verify_certificates, errstr))
1786 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1787 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1788 state->exp_tls_verify_certificates = NULL;
1790 if (state->tls_crl && *state->tls_crl)
1791 if (!Expand_check_tlsvar(tls_crl, errstr))
1794 if (!(state->exp_tls_verify_certificates &&
1795 *state->exp_tls_verify_certificates))
1798 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1799 /* With no tls_verify_certificates, we ignore tls_crl too */
1806 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1809 rc = creds_load_cabundle(state, state->exp_tls_verify_certificates, host, errstr);
1810 if (rc != OK) return rc;
1815 debug_printf("%s CA bundle was preloaded\n", host ? "client" : "server");
1816 state->exp_tls_verify_certificates = US state->tls_verify_certificates;
1818 #ifdef SUPPORT_CA_DIR
1819 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1820 when using the directory-of-certs config model. */
1821 if (state->lib_state.ca_rdn_emulate)
1822 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1827 if (!state->lib_state.crl)
1829 if ( state->tls_crl && *state->tls_crl
1830 && state->exp_tls_crl && *state->exp_tls_crl)
1831 return creds_load_crl(state, state->exp_tls_crl, errstr);
1836 debug_printf("%s CRL was preloaded\n", host ? "client" : "server");
1837 state->exp_tls_crl = US state->tls_crl;
1846 /*************************************************
1847 * Set X.509 state variables *
1848 *************************************************/
1850 /* In GnuTLS, the registered cert/key are not replaced by a later
1851 set of a cert/key, so for SNI support we need a whole new x509_cred
1852 structure. Which means various other non-re-expanded pieces of state
1853 need to be re-set in the new struct, so the setting logic is pulled
1857 state exim_gnutls_state_st *
1858 errstr error string pointer
1860 Returns: OK/DEFER/FAIL
1864 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1867 const host_item *host = state->host; /* macro should be reconsidered? */
1869 #ifndef GNUTLS_AUTO_DHPARAMS
1870 /* Create D-H parameters, or read them from the cache file. This function does
1871 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1872 client-side params. */
1876 if (!dh_server_params)
1877 if ((rc = init_server_dh(errstr)) != OK) return rc;
1879 /* Unnecessary & discouraged with 3.6.0 or later */
1880 gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
1884 /* Link the credentials to the session. */
1886 if ((rc = gnutls_credentials_set(state->session,
1887 GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))
1888 return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr);
1893 /*************************************************
1894 * Initialize for GnuTLS *
1895 *************************************************/
1898 /* Called from both server and client code. In the case of a server, errors
1899 before actual TLS negotiation return DEFER.
1902 host connected host, if client; NULL if server
1903 ob tranport options block, if client; NULL if server
1904 require_ciphers tls_require_ciphers setting
1905 caller_state returned state-info structure
1906 errstr error string pointer
1908 Returns: OK/DEFER/FAIL
1913 const host_item *host,
1914 smtp_transport_options_block * ob,
1915 const uschar * require_ciphers,
1916 exim_gnutls_state_st **caller_state,
1920 exim_gnutls_state_st * state;
1924 if (!exim_gnutls_base_init_done)
1929 /* For client-side sessions we allocate a context. This lets us run
1930 several in parallel. */
1932 int old_pool = store_pool;
1933 store_pool = POOL_PERM;
1934 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
1935 store_pool = old_pool;
1937 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1938 state->lib_state = ob->tls_preload;
1940 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
1941 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
1943 state->tls_certificate = ob->tls_certificate;
1944 state->tls_privatekey = ob->tls_privatekey;
1945 state->tls_sni = ob->tls_sni;
1946 state->tls_verify_certificates = ob->tls_verify_certificates;
1947 state->tls_crl = ob->tls_crl;
1951 /* Server operations always use the one state_server context. It is not
1952 shared because we have forked a fresh process for every receive. However it
1953 can get re-used for successive TLS sessions on a single TCP connection. */
1955 state = &state_server;
1957 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
1958 rc = gnutls_init(&state->session, GNUTLS_SERVER);
1960 state->tls_certificate = tls_certificate;
1961 state->tls_privatekey = tls_privatekey;
1962 state->tls_sni = NULL;
1963 state->tls_verify_certificates = tls_verify_certificates;
1964 state->tls_crl = tls_crl;
1967 return tls_error_gnu(US"gnutls_init", rc, host, errstr);
1969 state->tls_require_ciphers = require_ciphers;
1972 /* This handles the variables that might get re-expanded after TLS SNI;
1973 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1976 debug_printf("Expanding various TLS configuration options for session credentials\n");
1977 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
1979 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1980 requires a new structure afterwards. */
1982 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
1984 /* set SNI in client, only */
1987 if (!expand_check(state->tls_sni, US"tls_out_sni", &state->tlsp->sni, errstr))
1989 if (state->tlsp->sni && *state->tlsp->sni)
1992 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
1993 sz = Ustrlen(state->tlsp->sni);
1994 if ((rc = gnutls_server_name_set(state->session,
1995 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
1996 return tls_error_gnu(US"gnutls_server_name_set", rc, host, errstr);
1999 else if (state->tls_sni)
2000 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
2001 "have an SNI set for a server [%s]\n", state->tls_sni);
2003 if (!state->lib_state.pri_string)
2005 const uschar * p = NULL;
2006 const char * errpos;
2008 /* This is the priority string support,
2009 http://www.gnutls.org/manual/html_node/Priority-Strings.html
2010 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
2011 This was backwards incompatible, but means Exim no longer needs to track
2012 all algorithms and provide string forms for them. */
2014 if (state->tls_require_ciphers && *state->tls_require_ciphers)
2016 if (!Expand_check_tlsvar(tls_require_ciphers, errstr))
2018 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
2020 p = state->exp_tls_require_ciphers;
2021 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
2025 if ((rc = creds_load_pristring(state, p, &errpos)))
2026 return tls_error_gnu(string_sprintf(
2027 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
2028 p, errpos - CS p, errpos),
2033 DEBUG(D_tls) debug_printf("cipher list preloaded\n");
2034 state->exp_tls_require_ciphers = US state->tls_require_ciphers;
2038 if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))
2039 return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr);
2041 /* This also sets the server ticket expiration time to the same, and
2042 the STEK rotation time to 3x. */
2044 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
2046 /* Reduce security in favour of increased compatibility, if the admin
2047 decides to make that trade-off. */
2048 if (gnutls_compat_mode)
2050 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
2051 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
2052 gnutls_session_enable_compatibility_mode(state->session);
2054 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
2058 *caller_state = state;
2064 /*************************************************
2065 * Extract peer information *
2066 *************************************************/
2068 static const uschar *
2069 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
2070 gnutls_mac_algorithm_t mac)
2073 gnutls_kx_algorithm_t kx_i;
2074 gnutls_cipher_algorithm_t cipher_i;
2075 gnutls_mac_algorithm_t mac_i;
2078 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
2080 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
2081 return cipher_stdname(cs_id[0], cs_id[1]);
2087 /* Called from both server and client code.
2088 Only this is allowed to set state->peerdn and state->have_set_peerdn
2089 and we use that to detect double-calls.
2091 NOTE: the state blocks last while the TLS connection is up, which is fine
2092 for logging in the server side, but for the client side, we log after teardown
2093 in src/deliver.c. While the session is up, we can twist about states and
2094 repoint tls_* globals, but those variables used for logging or other variable
2095 expansion that happens _after_ delivery need to have a longer life-time.
2097 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
2098 doing this more than once per generation of a state context. We set them in
2099 the state context, and repoint tls_* to them. After the state goes away, the
2100 tls_* copies of the pointers remain valid and client delivery logging is happy.
2102 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
2106 state exim_gnutls_state_st *
2107 errstr pointer to error string
2109 Returns: OK/DEFER/FAIL
2113 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
2115 gnutls_session_t session = state->session;
2116 const gnutls_datum_t * cert_list;
2118 unsigned int cert_list_size = 0;
2119 gnutls_protocol_t protocol;
2120 gnutls_cipher_algorithm_t cipher;
2121 gnutls_kx_algorithm_t kx;
2122 gnutls_mac_algorithm_t mac;
2123 gnutls_certificate_type_t ct;
2124 gnutls_x509_crt_t crt;
2128 if (state->have_set_peerdn)
2130 state->have_set_peerdn = TRUE;
2132 state->peerdn = NULL;
2135 cipher = gnutls_cipher_get(session);
2136 protocol = gnutls_protocol_get_version(session);
2137 mac = gnutls_mac_get(session);
2139 #ifdef GNUTLS_TLS1_3
2140 protocol >= GNUTLS_TLS1_3 ? 0 :
2142 gnutls_kx_get(session);
2144 old_pool = store_pool;
2146 tls_support * tlsp = state->tlsp;
2147 store_pool = POOL_PERM;
2149 #ifdef SUPPORT_GNUTLS_SESS_DESC
2152 uschar * s = US gnutls_session_get_desc(session), c;
2154 /* Nikos M suggests we use this by preference. It returns like:
2155 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
2157 For partial back-compat, put a colon after the TLS version, replace the
2158 )-( grouping with __, replace in-group - with _ and append the :keysize. */
2160 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
2162 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
2164 tlsp->ver = string_copyn(g->s, g->ptr);
2165 for (uschar * p = US tlsp->ver; *p; p++)
2166 if (*p == '-') { *p = '\0'; break; } /* TLS1.0-PKIX -> TLS1.0 */
2168 g = string_catn(g, US":", 1);
2169 if (*s) s++; /* now on _ between groups */
2172 for (*++s && ++s; (c = *s) && c != ')'; s++)
2173 g = string_catn(g, c == '-' ? US"_" : s, 1);
2174 /* now on ) closing group */
2175 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
2176 /* now on _ between groups */
2178 g = string_catn(g, US":", 1);
2179 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
2180 state->ciphersuite = string_from_gstring(g);
2183 state->ciphersuite = string_sprintf("%s:%s:%d",
2184 gnutls_protocol_get_name(protocol),
2185 gnutls_cipher_suite_get_name(kx, cipher, mac),
2186 (int) gnutls_cipher_get_key_size(cipher) * 8);
2188 /* I don't see a way that spaces could occur, in the current GnuTLS
2189 code base, but it was a concern in the old code and perhaps older GnuTLS
2190 releases did return "TLS 1.0"; play it safe, just in case. */
2192 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
2193 tlsp->ver = string_copyn(state->ciphersuite,
2194 Ustrchr(state->ciphersuite, ':') - state->ciphersuite);
2197 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
2199 tlsp->cipher = state->ciphersuite;
2200 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
2202 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
2204 store_pool = old_pool;
2207 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
2209 if (!cert_list || cert_list_size == 0)
2211 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
2212 cert_list, cert_list_size);
2213 if (state->verify_requirement >= VERIFY_REQUIRED)
2214 return tls_error(US"certificate verification failed",
2215 US"no certificate received from peer", state->host, errstr);
2219 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
2221 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
2223 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
2224 if (state->verify_requirement >= VERIFY_REQUIRED)
2225 return tls_error(US"certificate verification not possible, unhandled type",
2226 ctn, state->host, errstr);
2230 #define exim_gnutls_peer_err(Label) \
2232 if (rc != GNUTLS_E_SUCCESS) \
2234 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
2235 (Label), gnutls_strerror(rc)); \
2236 if (state->verify_requirement >= VERIFY_REQUIRED) \
2237 return tls_error_gnu((Label), rc, state->host, errstr); \
2242 rc = import_cert(&cert_list[0], &crt);
2243 exim_gnutls_peer_err(US"cert 0");
2245 state->tlsp->peercert = state->peercert = crt;
2248 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
2249 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
2251 exim_gnutls_peer_err(US"getting size for cert DN failed");
2252 return FAIL; /* should not happen */
2254 dn_buf = store_get_perm(sz, TRUE); /* tainted */
2255 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
2256 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
2258 state->peerdn = dn_buf;
2261 #undef exim_gnutls_peer_err
2267 /*************************************************
2268 * Verify peer certificate *
2269 *************************************************/
2271 /* Called from both server and client code.
2272 *Should* be using a callback registered with
2273 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
2274 the peer information, but that's too new for some OSes.
2277 state exim_gnutls_state_st *
2278 errstr where to put an error message
2281 FALSE if the session should be rejected
2282 TRUE if the cert is okay or we just don't care
2286 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
2291 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
2293 rc = peer_status(state, errstr);
2295 if (state->verify_requirement == VERIFY_NONE)
2298 if (rc != OK || !state->peerdn)
2300 verify = GNUTLS_CERT_INVALID;
2301 *errstr = US"certificate not supplied";
2307 if (state->verify_requirement == VERIFY_DANE && state->host)
2309 /* Using dane_verify_session_crt() would be easy, as it does it all for us
2310 including talking to a DNS resolver. But we want to do that bit ourselves
2311 as the testsuite intercepts and fakes its own DNS environment. */
2316 const gnutls_datum_t * certlist =
2317 gnutls_certificate_get_peers(state->session, &lsize);
2318 int usage = tls_out.tlsa_usage;
2320 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2321 /* Split the TLSA records into two sets, TA and EE selectors. Run the
2322 dane-verification separately so that we know which selector verified;
2323 then we know whether to do name-verification (needed for TA but not EE). */
2325 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
2326 { /* a mixed-usage bundle */
2331 for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
2334 dd = store_get(nrec * sizeof(uschar *), FALSE);
2335 ddl = store_get(nrec * sizeof(int), FALSE);
2338 if ((rc = dane_state_init(&s, 0)))
2341 for (usage = DANESSL_USAGE_DANE_EE;
2342 usage >= DANESSL_USAGE_DANE_TA; usage--)
2343 { /* take records with this usage */
2344 for (j = i = 0; i < nrec; i++)
2345 if (state->dane_data[i][0] == usage)
2347 dd[j] = state->dane_data[i];
2348 ddl[j++] = state->dane_data_len[i];
2355 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
2358 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
2359 gnutls_certificate_type_get(state->session),
2361 usage == DANESSL_USAGE_DANE_EE
2362 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2366 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
2368 else if (verify == 0) /* verification passed */
2376 if (rc) goto tlsa_prob;
2381 if ( (rc = dane_state_init(&s, 0))
2382 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
2384 || (rc = dane_verify_crt_raw(s, certlist, lsize,
2385 gnutls_certificate_type_get(state->session),
2387 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2388 usage == (1 << DANESSL_USAGE_DANE_EE)
2389 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2398 if (verify != 0) /* verification failed */
2401 (void) dane_verification_status_print(verify, &str, 0);
2402 *errstr = US str.data; /* don't bother to free */
2406 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2407 /* If a TA-mode TLSA record was used for verification we must additionally
2408 verify the cert name (but not the CA chain). For EE-mode, skip it. */
2410 if (usage & (1 << DANESSL_USAGE_DANE_EE))
2413 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2416 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2417 /* Assume that the name on the A-record is the one that should be matching
2418 the cert. An alternate view is that the domain part of the email address
2419 is also permissible. */
2421 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2422 CS state->host->name))
2424 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2429 #endif /*SUPPORT_DANE*/
2431 rc = gnutls_certificate_verify_peers2(state->session, &verify);
2434 /* Handle the result of verification. INVALID is set if any others are. */
2436 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
2438 state->peer_cert_verified = FALSE;
2441 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
2446 if (gnutls_certificate_verification_status_print(verify,
2447 gnutls_certificate_type_get(state->session), &txt, 0)
2448 == GNUTLS_E_SUCCESS)
2450 debug_printf("%s\n", txt.data);
2451 gnutls_free(txt.data);
2455 *errstr = verify & GNUTLS_CERT_REVOKED
2456 ? US"certificate revoked" : US"certificate invalid";
2460 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
2461 *errstr, state->peerdn ? state->peerdn : US"<unset>");
2463 if (state->verify_requirement >= VERIFY_REQUIRED)
2466 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
2471 /* Client side, check the server's certificate name versus the name on the
2472 A-record for the connection we made. What to do for server side - what name
2473 to use for client? We document that there is no such checking for server
2476 if ( state->exp_tls_verify_cert_hostnames
2477 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2478 CS state->exp_tls_verify_cert_hostnames)
2482 debug_printf("TLS certificate verification failed: cert name mismatch\n");
2483 if (state->verify_requirement >= VERIFY_REQUIRED)
2488 state->peer_cert_verified = TRUE;
2489 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
2490 state->peerdn ? state->peerdn : US"<unset>");
2494 state->tlsp->peerdn = state->peerdn;
2499 *errstr = string_sprintf("TLSA record problem: %s",
2500 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
2504 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
2511 /* ------------------------------------------------------------------------ */
2514 /* Logging function which can be registered with
2515 * gnutls_global_set_log_function()
2516 * gnutls_global_set_log_level() 0..9
2518 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2520 exim_gnutls_logger_cb(int level, const char *message)
2522 size_t len = strlen(message);
2525 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2528 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2529 message[len-1] == '\n' ? "" : "\n");
2534 /* Called after client hello, should handle SNI work.
2535 This will always set tls_sni (state->received_sni) if available,
2536 and may trigger presenting different certificates,
2537 if state->trigger_sni_changes is TRUE.
2539 Should be registered with
2540 gnutls_handshake_set_post_client_hello_function()
2542 "This callback must return 0 on success or a gnutls error code to terminate the
2545 For inability to get SNI information, we return 0.
2546 We only return non-zero if re-setup failed.
2547 Only used for server-side TLS.
2551 exim_sni_handling_cb(gnutls_session_t session)
2553 char sni_name[MAX_HOST_LEN];
2554 size_t data_len = MAX_HOST_LEN;
2555 exim_gnutls_state_st *state = &state_server;
2556 unsigned int sni_type;
2558 uschar * dummy_errstr;
2560 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2561 if (rc != GNUTLS_E_SUCCESS)
2564 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2565 debug_printf("TLS: no SNI presented in handshake\n");
2567 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2568 gnutls_strerror(rc), rc);
2572 if (sni_type != GNUTLS_NAME_DNS)
2574 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2578 /* We now have a UTF-8 string in sni_name */
2579 old_pool = store_pool;
2580 store_pool = POOL_PERM;
2581 state->received_sni = string_copy_taint(US sni_name, TRUE);
2582 store_pool = old_pool;
2584 /* We set this one now so that variable expansions below will work */
2585 state->tlsp->sni = state->received_sni;
2587 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2588 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2590 if (!state->trigger_sni_changes)
2593 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2595 /* If the setup of certs/etc failed before handshake, TLS would not have
2596 been offered. The best we can do now is abort. */
2597 return GNUTLS_E_APPLICATION_ERROR_MIN;
2600 rc = tls_set_remaining_x509(state, &dummy_errstr);
2601 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2608 #ifndef DISABLE_EVENT
2610 We use this callback to get observability and detail-level control
2611 for an exim TLS connection (either direction), raising a tls:cert event
2612 for each cert in the chain presented by the peer. Any event
2613 can deny verification.
2615 Return 0 for the handshake to continue or non-zero to terminate.
2619 verify_cb(gnutls_session_t session)
2621 const gnutls_datum_t * cert_list;
2622 unsigned int cert_list_size = 0;
2623 gnutls_x509_crt_t crt;
2626 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2628 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2629 while (cert_list_size--)
2631 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2633 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2634 cert_list_size, gnutls_strerror(rc));
2638 state->tlsp->peercert = crt;
2639 if ((yield = event_raise(state->event_action,
2640 US"tls:cert", string_sprintf("%d", cert_list_size))))
2642 log_write(0, LOG_MAIN,
2643 "SSL verify denied by event-action: depth=%d: %s",
2644 cert_list_size, yield);
2645 return 1; /* reject */
2647 state->tlsp->peercert = NULL;
2657 ddump(gnutls_datum_t * d)
2659 gstring * g = string_get((d->size+1) * 2);
2660 uschar * s = d->data;
2661 for (unsigned i = d->size; i > 0; i--, s++)
2663 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2664 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2670 post_handshake_debug(exim_gnutls_state_st * state)
2672 #ifdef SUPPORT_GNUTLS_SESS_DESC
2673 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2676 #ifdef SUPPORT_GNUTLS_KEYLOG
2677 # ifdef EXIM_HAVE_TLS1_3
2678 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2683 gnutls_datum_t c, s;
2685 /* For TLS1.2 we only want the client random and the master secret */
2686 gnutls_session_get_random(state->session, &c, &s);
2687 gnutls_session_get_master_secret(state->session, &s);
2690 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2693 debug_printf("To get keying info for TLS1.3 is hard:\n"
2694 " Set environment variable SSLKEYLOGFILE to a filename relative to the spool directory,\n"
2695 " and make sure it is writable by the Exim runtime user.\n"
2696 " Add SSLKEYLOGFILE to keep_environment in the exim config.\n"
2697 " Start Exim as root.\n"
2698 " If using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
2699 " (works for TLS1.2 also, and saves cut-paste into file).\n"
2700 " Trying to use add_environment for this will not work\n");
2705 #ifdef EXIM_HAVE_TLS_RESUME
2707 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2708 unsigned incoming, const gnutls_datum_t * msg)
2710 DEBUG(D_tls) debug_printf("newticket cb\n");
2711 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2716 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2718 /* Should the server offer session resumption? */
2719 tls_in.resumption = RESUME_SUPPORTED;
2720 if (verify_check_host(&tls_resumption_hosts) == OK)
2723 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2724 an offered resumption is unacceptable. We lose one resumption per ticket
2725 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2726 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2727 least they go out in a single packet. */
2729 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2730 &server_sessticket_key)))
2731 tls_in.resumption |= RESUME_SERVER_TICKET;
2734 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2736 /* Try to tell if we see a ticket request */
2737 gnutls_handshake_set_hook_function(state->session,
2738 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2743 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2745 if (gnutls_session_resumption_requested(state->session))
2747 /* This tells us the client sent a full ticket. We use a
2748 callback on session-ticket request, elsewhere, to tell
2749 if a client asked for a ticket. */
2751 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2752 DEBUG(D_tls) debug_printf("client requested resumption\n");
2754 if (gnutls_session_is_resumed(state->session))
2756 tls_in.resumption |= RESUME_USED;
2757 DEBUG(D_tls) debug_printf("Session resumed\n");
2761 /* ------------------------------------------------------------------------ */
2762 /* Exported functions */
2767 /*************************************************
2768 * Start a TLS session in a server *
2769 *************************************************/
2771 /* This is called when Exim is running as a server, after having received
2772 the STARTTLS command. It must respond to that command, and then negotiate
2776 errstr pointer to error string
2778 Returns: OK on success
2779 DEFER for errors before the start of the negotiation
2780 FAIL for errors during the negotiation; the server can't
2785 tls_server_start(uschar ** errstr)
2788 exim_gnutls_state_st * state = NULL;
2790 /* Check for previous activation */
2791 if (tls_in.active.sock >= 0)
2793 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2794 smtp_printf("554 Already in TLS\r\n", FALSE);
2798 /* Initialize the library. If it fails, it will already have logged the error
2799 and sent an SMTP response. */
2801 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2804 #ifdef MEASURE_TIMING
2806 gettimeofday(&t0, NULL);
2809 if ((rc = tls_init(NULL, NULL,
2810 tls_require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2812 #ifdef MEASURE_TIMING
2813 report_time_since(&t0, US"server tls_init (delta)");
2817 #ifdef EXIM_HAVE_TLS_RESUME
2818 tls_server_resume_prehandshake(state);
2821 /* If this is a host for which certificate verification is mandatory or
2822 optional, set up appropriately. */
2824 if (verify_check_host(&tls_verify_hosts) == OK)
2827 debug_printf("TLS: a client certificate will be required\n");
2828 state->verify_requirement = VERIFY_REQUIRED;
2829 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2831 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2834 debug_printf("TLS: a client certificate will be requested but not required\n");
2835 state->verify_requirement = VERIFY_OPTIONAL;
2836 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2841 debug_printf("TLS: a client certificate will not be requested\n");
2842 state->verify_requirement = VERIFY_NONE;
2843 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2846 #ifndef DISABLE_EVENT
2849 state->event_action = event_action;
2850 gnutls_session_set_ptr(state->session, state);
2851 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
2855 /* Register SNI handling; always, even if not in tls_certificate, so that the
2856 expansion variable $tls_sni is always available. */
2858 gnutls_handshake_set_post_client_hello_function(state->session,
2859 exim_sni_handling_cb);
2861 /* Set context and tell client to go ahead, except in the case of TLS startup
2862 on connection, where outputting anything now upsets the clients and tends to
2863 make them disconnect. We need to have an explicit fflush() here, to force out
2864 the response. Other smtp_printf() calls do not need it, because in non-TLS
2865 mode, the fflush() happens when smtp_getc() is called. */
2867 if (!state->tlsp->on_connect)
2869 smtp_printf("220 TLS go ahead\r\n", FALSE);
2873 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2874 that the GnuTLS library doesn't.
2875 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2876 to set (and clear down afterwards) up a pull-timeout callback function that does
2877 a select, so we're no better off unless avoiding signals becomes an issue. */
2879 gnutls_transport_set_ptr2(state->session,
2880 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
2881 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
2882 state->fd_in = fileno(smtp_in);
2883 state->fd_out = fileno(smtp_out);
2885 sigalrm_seen = FALSE;
2886 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2888 rc = gnutls_handshake(state->session);
2889 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2892 if (rc != GNUTLS_E_SUCCESS)
2894 /* It seems that, except in the case of a timeout, we have to close the
2895 connection right here; otherwise if the other end is running OpenSSL it hangs
2896 until the server times out. */
2900 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
2901 gnutls_db_remove_session(state->session);
2905 tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr);
2906 (void) gnutls_alert_send_appropriate(state->session, rc);
2907 gnutls_deinit(state->session);
2908 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
2909 state->lib_state = null_tls_preload;
2911 shutdown(state->fd_out, SHUT_WR);
2912 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
2913 (void)fclose(smtp_out);
2914 (void)fclose(smtp_in);
2915 smtp_out = smtp_in = NULL;
2921 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
2922 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
2923 tls_in.ext_master_secret = TRUE;
2926 #ifdef EXIM_HAVE_TLS_RESUME
2927 tls_server_resume_posthandshake(state);
2930 DEBUG(D_tls) post_handshake_debug(state);
2932 /* Verify after the fact */
2934 if (!verify_certificate(state, errstr))
2936 if (state->verify_requirement != VERIFY_OPTIONAL)
2938 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
2942 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2946 /* Sets various Exim expansion variables; always safe within server */
2948 extract_exim_vars_from_tls_state(state);
2950 /* TLS has been set up. Adjust the input functions to read via TLS,
2951 and initialize appropriately. */
2953 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2955 receive_getc = tls_getc;
2956 receive_getbuf = tls_getbuf;
2957 receive_get_cache = tls_get_cache;
2958 receive_ungetc = tls_ungetc;
2959 receive_feof = tls_feof;
2960 receive_ferror = tls_ferror;
2961 receive_smtp_buffered = tls_smtp_buffered;
2970 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
2971 smtp_transport_options_block * ob)
2973 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2975 state->exp_tls_verify_cert_hostnames =
2977 string_domain_utf8_to_alabel(host->certname, NULL);
2982 debug_printf("TLS: server cert verification includes hostname: \"%s\"\n",
2983 state->exp_tls_verify_cert_hostnames);
2991 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2992 GnuTLS-DANE's preferred format. Hang it on the state str for later
2993 use in DANE verification.
2995 We point at the dnsa data not copy it, so it must remain valid until
2996 after verification is done.*/
2999 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
3003 const char ** dane_data;
3004 int * dane_data_len;
3007 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3008 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3009 ) if (rr->type == T_TLSA) i++;
3011 dane_data = store_get(i * sizeof(uschar *), FALSE);
3012 dane_data_len = store_get(i * sizeof(int), FALSE);
3015 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3016 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3017 ) if (rr->type == T_TLSA && rr->size > 3)
3019 const uschar * p = rr->data;
3020 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
3021 uint8_t usage = p[0], sel = p[1], type = p[2];
3024 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
3026 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
3027 || (sel != 0 && sel != 1)
3032 case 0: /* Full: cannot check at present */
3034 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
3036 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
3041 tls_out.tlsa_usage |= 1<<usage;
3042 dane_data[i] = CS p;
3043 dane_data_len[i++] = rr->size;
3046 if (!i) return FALSE;
3048 dane_data[i] = NULL;
3049 dane_data_len[i] = 0;
3051 state->dane_data = (char * const *)dane_data;
3052 state->dane_data_len = dane_data_len;
3059 #ifdef EXIM_HAVE_TLS_RESUME
3060 /* On the client, get any stashed session for the given IP from hints db
3061 and apply it to the ssl-connection for attempted resumption. Although
3062 there is a gnutls_session_ticket_enable_client() interface it is
3063 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
3064 by deafult". There seems to be no way to disable them, so even hosts not
3065 enabled by the transport option will be sent a ticket request. We will
3066 however avoid storing and retrieving session information. */
3069 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
3070 host_item * host, smtp_transport_options_block * ob)
3072 tlsp->resumption = RESUME_SUPPORTED;
3073 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3075 dbdata_tls_session * dt;
3077 open_db dbblock, * dbm_file;
3080 debug_printf("check for resumable session for %s\n", host->address);
3081 tlsp->host_resumable = TRUE;
3082 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3083 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
3085 /* Key for the db is the IP. We'd like to filter the retrieved session
3086 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
3088 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
3089 if (!(rc = gnutls_session_set_data(session,
3090 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
3092 DEBUG(D_tls) debug_printf("good session\n");
3093 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3095 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
3096 US gnutls_strerror(rc));
3097 dbfn_close(dbm_file);
3104 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
3106 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
3107 but this flag is not set until the second. TLS 1.3 it's the other way about.
3108 Keep both calls as the session data cannot be extracted before handshake
3111 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
3116 DEBUG(D_tls) debug_printf("server offered session ticket\n");
3117 tlsp->ticket_received = TRUE;
3118 tlsp->resumption |= RESUME_SERVER_TICKET;
3120 if (tlsp->host_resumable)
3121 if (!(rc = gnutls_session_get_data2(session, &tkt)))
3123 open_db dbblock, * dbm_file;
3124 int dlen = sizeof(dbdata_tls_session) + tkt.size;
3125 dbdata_tls_session * dt = store_get(dlen, TRUE);
3127 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
3128 memcpy(dt->session, tkt.data, tkt.size);
3129 gnutls_free(tkt.data);
3131 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3133 /* key for the db is the IP */
3134 dbfn_delete(dbm_file, host->address);
3135 dbfn_write(dbm_file, host->address, dt, dlen);
3136 dbfn_close(dbm_file);
3139 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
3143 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
3148 /* With a TLS1.3 session, the ticket(s) are not seen until
3149 the first data read is attempted. And there's often two of them.
3150 Pick them up with this callback. We are also called for 1.2
3154 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
3155 unsigned incoming, const gnutls_datum_t * msg)
3157 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
3158 tls_support * tlsp = state->tlsp;
3160 DEBUG(D_tls) debug_printf("newticket cb\n");
3162 if (!tlsp->ticket_received)
3163 tls_save_session(tlsp, sess, state->host);
3169 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
3170 tls_support * tlsp, host_item * host,
3171 smtp_transport_options_block * ob)
3173 gnutls_session_set_ptr(state->session, state);
3174 gnutls_handshake_set_hook_function(state->session,
3175 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
3177 tls_retrieve_session(tlsp, state->session, host, ob);
3181 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
3182 tls_support * tlsp, host_item * host)
3184 if (gnutls_session_is_resumed(state->session))
3186 DEBUG(D_tls) debug_printf("Session resumed\n");
3187 tlsp->resumption |= RESUME_USED;
3190 tls_save_session(tlsp, state->session, host);
3192 #endif /* !DISABLE_TLS_RESUME */
3195 /*************************************************
3196 * Start a TLS session in a client *
3197 *************************************************/
3199 /* Called from the smtp transport after STARTTLS has been accepted.
3202 cctx connection context
3203 conn_args connection details
3204 cookie datum for randomness (not used)
3205 tlsp record details of channel configuration here; must be non-NULL
3206 errstr error string pointer
3208 Returns: TRUE for success with TLS session context set in smtp context,
3213 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3214 void * cookie ARG_UNUSED,
3215 tls_support * tlsp, uschar ** errstr)
3217 host_item * host = conn_args->host; /* for msgs and option-tests */
3218 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3219 smtp_transport_options_block * ob = tb
3220 ? (smtp_transport_options_block *)tb->options_block
3221 : &smtp_transport_option_defaults;
3223 exim_gnutls_state_st * state = NULL;
3224 uschar * cipher_list = NULL;
3226 #ifndef DISABLE_OCSP
3228 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3229 BOOL request_ocsp = require_ocsp ? TRUE
3230 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3233 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
3236 /* If dane is flagged, have either request or require dane for this host, and
3237 a TLSA record found. Therefore, dane verify required. Which implies cert must
3238 be requested and supplied, dane verify must pass, and cert verify irrelevant
3239 (incl. hostnames), and (caller handled) require_tls and sni=$domain */
3241 if (conn_args->dane && ob->dane_require_tls_ciphers)
3243 /* not using Expand_check_tlsvar because not yet in state */
3244 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3245 &cipher_list, errstr))
3247 cipher_list = cipher_list && *cipher_list
3248 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
3253 cipher_list = ob->tls_require_ciphers;
3256 #ifdef MEASURE_TIMING
3258 gettimeofday(&t0, NULL);
3261 if (tls_init(host, ob, cipher_list, &state, tlsp, errstr) != OK)
3264 #ifdef MEASURE_TIMING
3265 report_time_since(&t0, US"client tls_init (delta)");
3270 int dh_min_bits = ob->tls_dh_min_bits;
3271 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
3274 debug_printf("WARNING: tls_dh_min_bits far too low,"
3275 " clamping %d up to %d\n",
3276 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
3277 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
3280 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
3281 " acceptable bits to %d\n",
3283 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
3286 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
3287 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
3288 the specified host patterns if one of them is defined */
3291 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
3294 debug_printf("TLS: server certificate DANE required\n");
3295 state->verify_requirement = VERIFY_DANE;
3296 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3300 if ( ( state->exp_tls_verify_certificates
3301 && !ob->tls_verify_hosts
3302 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
3304 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3307 tls_client_setup_hostname_checks(host, state, ob);
3309 debug_printf("TLS: server certificate verification required\n");
3310 state->verify_requirement = VERIFY_REQUIRED;
3311 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3313 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3315 tls_client_setup_hostname_checks(host, state, ob);
3317 debug_printf("TLS: server certificate verification optional\n");
3318 state->verify_requirement = VERIFY_OPTIONAL;
3319 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
3324 debug_printf("TLS: server certificate verification not required\n");
3325 state->verify_requirement = VERIFY_NONE;
3326 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
3329 #ifndef DISABLE_OCSP
3330 /* supported since GnuTLS 3.1.3 */
3333 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
3334 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
3335 NULL, 0, NULL)) != OK)
3337 tls_error_gnu(US"cert-status-req", rc, state->host, errstr);
3340 tlsp->ocsp = OCSP_NOT_RESP;
3344 #ifdef EXIM_HAVE_TLS_RESUME
3345 tls_client_resume_prehandshake(state, tlsp, host, ob);
3348 #ifndef DISABLE_EVENT
3349 if (tb && tb->event_action)
3351 state->event_action = tb->event_action;
3352 gnutls_session_set_ptr(state->session, state);
3353 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
3357 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
3358 state->fd_in = cctx->sock;
3359 state->fd_out = cctx->sock;
3361 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
3362 /* There doesn't seem to be a built-in timeout on connection. */
3364 sigalrm_seen = FALSE;
3365 ALARM(ob->command_timeout);
3367 rc = gnutls_handshake(state->session);
3368 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3371 if (rc != GNUTLS_E_SUCCESS)
3375 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
3376 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
3379 tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr);
3383 DEBUG(D_tls) post_handshake_debug(state);
3387 if (!verify_certificate(state, errstr))
3389 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
3393 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3394 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3395 tlsp->ext_master_secret = TRUE;
3398 #ifndef DISABLE_OCSP
3403 gnutls_datum_t stapling;
3404 gnutls_ocsp_resp_t resp;
3405 gnutls_datum_t printed;
3409 # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
3410 (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
3412 (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
3415 if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0
3416 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
3417 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
3420 debug_printf("%.4096s", printed.data);
3421 gnutls_free(printed.data);
3424 (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
3426 (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
3429 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
3431 tlsp->ocsp = OCSP_FAILED;
3432 tls_error(US"certificate status check failed", NULL, state->host, errstr);
3438 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
3439 tlsp->ocsp = OCSP_VFIED;
3444 #ifdef EXIM_HAVE_TLS_RESUME
3445 tls_client_resume_posthandshake(state, tlsp, host);
3448 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
3450 extract_exim_vars_from_tls_state(state);
3452 cctx->tls_ctx = state;
3459 /*************************************************
3460 * Close down a TLS session *
3461 *************************************************/
3463 /* This is also called from within a delivery subprocess forked from the
3464 daemon, to shut down the TLS library, without actually doing a shutdown (which
3465 would tamper with the TLS session in the parent process).
3468 ct_ctx client context pointer, or NULL for the one global server context
3469 shutdown 1 if TLS close-alert is to be sent,
3470 2 if also response to be waited for
3476 tls_close(void * ct_ctx, int shutdown)
3478 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3479 tls_support * tlsp = state->tlsp;
3481 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3485 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3486 shutdown > 1 ? " (with response-wait)" : "");
3489 gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
3493 if (!ct_ctx) /* server */
3495 receive_getc = smtp_getc;
3496 receive_getbuf = smtp_getbuf;
3497 receive_get_cache = smtp_get_cache;
3498 receive_ungetc = smtp_ungetc;
3499 receive_feof = smtp_feof;
3500 receive_ferror = smtp_ferror;
3501 receive_smtp_buffered = smtp_buffered;
3504 gnutls_deinit(state->session);
3505 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3506 state->lib_state = null_tls_preload;
3508 tlsp->active.sock = -1;
3509 tlsp->active.tls_ctx = NULL;
3510 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3511 tlsp->channelbinding = NULL;
3514 if (state->xfer_buffer) store_free(state->xfer_buffer);
3521 tls_refill(unsigned lim)
3523 exim_gnutls_state_st * state = &state_server;
3526 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, buffersize=%u)\n",
3527 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
3529 sigalrm_seen = FALSE;
3530 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3534 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
3535 MIN(ssl_xfer_buffer_size, lim));
3536 while (inbytes == GNUTLS_E_AGAIN);
3538 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3540 if (had_command_timeout) /* set by signal handler */
3541 smtp_command_timeout_exit(); /* does not return */
3542 if (had_command_sigterm)
3543 smtp_command_sigterm_exit();
3544 if (had_data_timeout)
3545 smtp_data_timeout_exit();
3546 if (had_data_sigint)
3547 smtp_data_sigint_exit();
3549 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3550 TLS session has been closed down, not that the socket itself has been closed
3551 down. Revert to non-TLS handling. */
3555 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3556 state->xfer_error = TRUE;
3560 else if (inbytes == 0)
3562 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3563 tls_close(NULL, TLS_NO_SHUTDOWN);
3567 /* Handle genuine errors */
3569 else if (inbytes < 0)
3571 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3572 record_io_error(state, (int) inbytes, US"recv", NULL);
3573 state->xfer_error = TRUE;
3576 #ifndef DISABLE_DKIM
3577 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3579 state->xfer_buffer_hwm = (int) inbytes;
3580 state->xfer_buffer_lwm = 0;
3584 /*************************************************
3585 * TLS version of getc *
3586 *************************************************/
3588 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3589 it refills the buffer via the GnuTLS reading function.
3590 Only used by the server-side TLS.
3592 This feeds DKIM and should be used for all message-body reads.
3594 Arguments: lim Maximum amount to read/buffer
3595 Returns: the next character or EOF
3599 tls_getc(unsigned lim)
3601 exim_gnutls_state_st * state = &state_server;
3603 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3604 if (!tls_refill(lim))
3605 return state->xfer_error ? EOF : smtp_getc(lim);
3607 /* Something in the buffer; return next uschar */
3609 return state->xfer_buffer[state->xfer_buffer_lwm++];
3613 tls_getbuf(unsigned * len)
3615 exim_gnutls_state_st * state = &state_server;
3619 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3620 if (!tls_refill(*len))
3622 if (!state->xfer_error) return smtp_getbuf(len);
3627 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3629 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3630 state->xfer_buffer_lwm += size;
3639 #ifndef DISABLE_DKIM
3640 exim_gnutls_state_st * state = &state_server;
3641 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3643 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3649 tls_could_read(void)
3651 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3652 || gnutls_record_check_pending(state_server.session) > 0;
3658 /*************************************************
3659 * Read bytes from TLS channel *
3660 *************************************************/
3662 /* This does not feed DKIM, so if the caller uses this for reading message body,
3663 then the caller must feed DKIM.
3666 ct_ctx client context pointer, or NULL for the one global server context
3670 Returns: the number of bytes read
3671 -1 after a failed read, including EOF
3675 tls_read(void * ct_ctx, uschar *buff, size_t len)
3677 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3683 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3685 debug_printf("*** PROBABLY A BUG *** " \
3686 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3687 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3690 debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, len=" SIZE_T_FMT ")\n",
3691 state->session, buff, len);
3695 inbytes = gnutls_record_recv(state->session, buff, len);
3696 while (inbytes == GNUTLS_E_AGAIN);
3698 if (inbytes > 0) return inbytes;
3701 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3705 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3706 record_io_error(state, (int)inbytes, US"recv", NULL);
3715 /*************************************************
3716 * Write bytes down TLS channel *
3717 *************************************************/
3721 ct_ctx client context pointer, or NULL for the one global server context
3724 more more data expected soon
3726 Calling with len zero and more unset will flush buffered writes. The buff
3727 argument can be null for that case.
3729 Returns: the number of bytes after a successful write,
3730 -1 after a failed write
3734 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3738 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3741 if (more && !state->corked)
3743 DEBUG(D_tls) debug_printf("gnutls_record_cork(session=%p)\n", state->session);
3744 gnutls_record_cork(state->session);
3745 state->corked = TRUE;
3749 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3750 buff, left, more ? ", more" : "");
3754 DEBUG(D_tls) debug_printf("gnutls_record_send(session=%p, buffer=%p, left=" SIZE_T_FMT ")\n",
3755 state->session, buff, left);
3759 outbytes = gnutls_record_send(state->session, buff, left);
3760 while (outbytes == GNUTLS_E_AGAIN);
3762 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
3766 #ifdef GNUTLS_E_PREMATURE_TERMINATION
3767 if ( outbytes == GNUTLS_E_PREMATURE_TERMINATION && errno == ECONNRESET
3768 && !ct_ctx && f.smtp_in_quit
3770 { /* Outlook, dammit */
3771 if (LOGGING(protocol_detail))
3772 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
3773 " SMTP response and TLS close\n", sender_host_address);
3775 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
3776 " client reset TCP before TLS close\n", sender_host_address);
3781 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
3782 record_io_error(state, outbytes, US"send", NULL);
3788 record_io_error(state, 0, US"send", US"TLS channel closed on write");
3799 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
3805 if (!more && state->corked)
3807 DEBUG(D_tls) debug_printf("gnutls_record_uncork(session=%p)\n", state->session);
3809 /* We can't use GNUTLS_RECORD_WAIT here, as it retries on
3810 GNUTLS_E_AGAIN || GNUTLS_E_INTR, which would break our timeout set by alarm().
3811 The GNUTLS_E_AGAIN should not happen ever, as our sockets are blocking anyway.
3812 But who knows. (That all relies on the fact that GNUTLS_E_INTR and GNUTLS_E_AGAIN
3813 match the EINTR and EAGAIN errno values.) */
3814 outbytes = gnutls_record_uncork(state->session, 0);
3815 while (outbytes == GNUTLS_E_AGAIN);
3819 record_io_error(state, len, US"uncork", NULL);
3823 state->corked = FALSE;
3833 /*************************************************
3834 * Random number generation *
3835 *************************************************/
3837 /* Pseudo-random number generation. The result is not expected to be
3838 cryptographically strong but not so weak that someone will shoot themselves
3839 in the foot using it as a nonce in input in some email header scheme or
3840 whatever weirdness they'll twist this into. The result should handle fork()
3841 and avoid repeating sequences. OpenSSL handles that for us.
3845 Returns a random number in range [0, max-1]
3848 #ifdef HAVE_GNUTLS_RND
3850 vaguely_random_number(int max)
3854 uschar smallbuf[sizeof(r)];
3859 needed_len = sizeof(r);
3860 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3861 asked for a number less than 10. */
3863 for (r = max, i = 0; r; ++i)
3869 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
3872 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback\n");
3873 return vaguely_random_number_fallback(max);
3876 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3879 /* We don't particularly care about weighted results; if someone wants
3880 * smooth distribution and cares enough then they should submit a patch then. */
3883 #else /* HAVE_GNUTLS_RND */
3885 vaguely_random_number(int max)
3887 return vaguely_random_number_fallback(max);
3889 #endif /* HAVE_GNUTLS_RND */
3894 /*************************************************
3895 * Let tls_require_ciphers be checked at startup *
3896 *************************************************/
3898 /* The tls_require_ciphers option, if set, must be something which the
3901 Returns: NULL on success, or error message
3905 tls_validate_require_cipher(void)
3908 uschar *expciphers = NULL;
3909 gnutls_priority_t priority_cache;
3911 uschar * dummy_errstr;
3913 #ifdef GNUTLS_AUTO_GLOBAL_INIT
3914 # define validate_check_rc(Label) do { \
3915 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \
3916 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3917 # define return_deinit(Label) do { return (Label); } while (0)
3919 # define validate_check_rc(Label) do { \
3920 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3921 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3922 # define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3925 if (exim_gnutls_base_init_done)
3926 log_write(0, LOG_MAIN|LOG_PANIC,
3927 "already initialised GnuTLS, Exim developer bug");
3929 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
3930 if (!gnutls_allow_auto_pkcs11)
3932 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
3933 validate_check_rc(US"gnutls_pkcs11_init");
3936 #ifndef GNUTLS_AUTO_GLOBAL_INIT
3937 rc = gnutls_global_init();
3938 validate_check_rc(US"gnutls_global_init()");
3940 exim_gnutls_base_init_done = TRUE;
3942 if (!(tls_require_ciphers && *tls_require_ciphers))
3943 return_deinit(NULL);
3945 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3947 return_deinit(US"failed to expand tls_require_ciphers");
3949 if (!(expciphers && *expciphers))
3950 return_deinit(NULL);
3953 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3955 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
3956 validate_check_rc(string_sprintf(
3957 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3958 expciphers, errpos - CS expciphers, errpos));
3960 #undef return_deinit
3961 #undef validate_check_rc
3962 #ifndef GNUTLS_AUTO_GLOBAL_INIT
3963 gnutls_global_deinit();
3972 /*************************************************
3973 * Report the library versions. *
3974 *************************************************/
3976 /* See a description in tls-openssl.c for an explanation of why this exists.
3978 Arguments: a FILE* to print the results to
3983 tls_version_report(FILE *f)
3985 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
3988 gnutls_check_version(NULL));
3991 #endif /*!MACRO_PREDEF*/
3994 /* End of tls-gnu.c */