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"
122 #if GNUTLS_VERSION_NUMBER >= 0x030200
123 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
124 # define EXIM_HAVE_ALPN
129 # include <gnutls/ocsp.h>
132 # include <gnutls/dane.h>
135 #include "tls-cipher-stdname.c"
142 # ifndef DISABLE_TLS_RESUME
143 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
145 # ifdef EXIM_HAVE_TLS1_3
146 builtin_macro_create(US"_HAVE_TLS1_3");
148 # ifdef EXIM_HAVE_OCSP
149 builtin_macro_create(US"_HAVE_TLS_OCSP");
151 # ifdef SUPPORT_SRV_OCSP_STACK
152 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
154 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
155 builtin_macro_create(US"_HAVE_TLS_CA_CACHE");
157 # ifdef EXIM_HAVE_ALPN
158 builtin_macro_create(US"_HAVE_TLS_ALPN");
167 gnutls_global_set_audit_log_function()
170 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
173 /* Local static variables for GnuTLS */
175 /* Values for verify_requirement */
177 enum peer_verify_requirement
178 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
180 /* This holds most state for server or client; with this, we can set up an
181 outbound TLS-enabled connection in an ACL callout, while not stomping all
182 over the TLS variables available for expansion.
184 Some of these correspond to variables in globals.c; those variables will
185 be set to point to content in one of these instances, as appropriate for
186 the stage of the process lifetime.
188 Not handled here: global tlsp->tls_channelbinding.
191 typedef struct exim_gnutls_state {
192 gnutls_session_t session;
194 exim_tlslib_state lib_state;
195 #define x509_cred libdata0
196 #define pri_cache libdata1
198 enum peer_verify_requirement verify_requirement;
202 BOOL peer_cert_verified:1;
203 BOOL peer_dane_verified:1;
204 BOOL trigger_sni_changes:1;
205 BOOL have_set_peerdn:1;
206 BOOL xfer_eof:1; /*XXX never gets set! */
212 const struct host_item *host; /* NULL if server */
213 gnutls_x509_crt_t peercert;
216 uschar *received_sni;
218 const uschar *tls_certificate;
219 const uschar *tls_privatekey;
220 const uschar *tls_sni; /* client send only, not received */
221 const uschar *tls_verify_certificates;
222 const uschar *tls_crl;
223 const uschar *tls_require_ciphers;
225 uschar *exp_tls_certificate;
226 uschar *exp_tls_privatekey;
227 uschar *exp_tls_verify_certificates;
229 uschar *exp_tls_require_ciphers;
230 const uschar *exp_tls_verify_cert_hostnames;
231 #ifndef DISABLE_EVENT
232 uschar *event_action;
235 char * const * dane_data;
236 const int * dane_data_len;
239 tls_support *tlsp; /* set in tls_init() */
244 } exim_gnutls_state_st;
246 static const exim_gnutls_state_st exim_gnutls_state_init = {
247 /* all elements not explicitly intialised here get 0/NULL/FALSE */
252 /* Not only do we have our own APIs which don't pass around state, assuming
253 it's held in globals, GnuTLS doesn't appear to let us register callback data
254 for callbacks, or as part of the session, so we have to keep a "this is the
255 context we're currently dealing with" pointer and rely upon being
256 single-threaded to keep from processing data on an inbound TLS connection while
257 talking to another TLS connection for an outbound check. This does mean that
258 there's no way for heart-beats to be responded to, for the duration of the
260 XXX But see gnutls_session_get_ptr()
263 static exim_gnutls_state_st state_server = {
264 /* all elements not explicitly intialised here get 0/NULL/FALSE */
269 #ifndef GNUTLS_AUTO_DHPARAMS
270 /* dh_params are initialised once within the lifetime of a process using TLS;
271 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
272 don't want to repeat this. */
274 static gnutls_dh_params_t dh_server_params = NULL;
277 static int ssl_session_timeout = 7200; /* Two hours */
279 static const uschar * const exim_default_gnutls_priority = US"NORMAL";
281 /* Guard library core initialisation */
283 static BOOL exim_gnutls_base_init_done = FALSE;
286 static BOOL gnutls_buggy_ocsp = FALSE;
287 static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
290 #ifdef EXIM_HAVE_ALPN
291 static int server_seen_alpn = -1; /* count of names */
293 #ifdef EXIM_HAVE_TLS_RESUME
294 static gnutls_datum_t server_sessticket_key;
298 /* ------------------------------------------------------------------------ */
301 #define MAX_HOST_LEN 255
303 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
304 the library logging; a value less than 0 disables the calls to set up logging
305 callbacks. GNuTLS also looks for an environment variable - except not for
306 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
307 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
308 but the env var must be added to /etc/sudoers too. */
309 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
310 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
313 #ifndef EXIM_CLIENT_DH_MIN_BITS
314 # define EXIM_CLIENT_DH_MIN_BITS 1024
317 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
318 can ask for a bit-strength. Without that, we stick to the constant we had
320 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
321 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
324 #define Expand_check_tlsvar(Varname, errstr) \
325 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
327 #if GNUTLS_VERSION_NUMBER >= 0x020c00
328 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
329 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
330 # define HAVE_GNUTLS_RND
331 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
332 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
333 * isn't available sometimes, so this needs to become a conditional
334 * compilation; the sanest way to deal with this being a problem on
335 * older OSes is to block it in the Local/Makefile with this compiler
337 # ifndef AVOID_GNUTLS_PKCS11
338 # define HAVE_GNUTLS_PKCS11
339 # endif /* AVOID_GNUTLS_PKCS11 */
345 /* ------------------------------------------------------------------------ */
346 /* Callback declarations */
348 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
349 static void exim_gnutls_logger_cb(int level, const char *message);
352 static int exim_sni_handling_cb(gnutls_session_t session);
354 #ifdef EXIM_HAVE_TLS_RESUME
356 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
357 unsigned incoming, const gnutls_datum_t * msg);
361 /*************************************************
363 *************************************************/
365 /* Called from lots of places when errors occur before actually starting to do
366 the TLS handshake, that is, while the session is still in clear. Always returns
367 DEFER for a server and FAIL for a client so that most calls can use "return
368 tls_error(...)" to do this processing and then give an appropriate return. A
369 single function is used for both server and client, because it is called from
370 some shared functions.
373 prefix text to include in the logged error
374 msg additional error string (may be NULL)
375 usually obtained from gnutls_strerror()
376 host NULL if setting up a server;
377 the connected host if setting up a client
378 errstr pointer to returned error string
380 Returns: OK/DEFER/FAIL
384 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
388 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
389 return host ? FAIL : DEFER;
394 tls_error_gnu(exim_gnutls_state_st * state, const uschar *prefix, int err,
397 return tls_error(prefix,
398 state && err == GNUTLS_E_FATAL_ALERT_RECEIVED
399 ? US gnutls_alert_get_name(gnutls_alert_get(state->session))
400 : US gnutls_strerror(err),
401 state ? state->host : NULL,
406 tls_error_sys(const uschar *prefix, int err, const host_item *host,
409 return tls_error(prefix, US strerror(err), host, errstr);
413 /* ------------------------------------------------------------------------ */
419 tls_is_buggy_ocsp(void)
422 uschar maj, mid, mic;
424 s = CUS gnutls_check_version(NULL);
428 while (*s && *s != '.') s++;
436 while (*s && *s != '.') s++;
438 return mic <= (mid == 3 ? 16 : 3);
448 tls_g_init(uschar ** errstr)
451 DEBUG(D_tls) debug_printf("GnuTLS global init required\n");
453 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
454 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
455 which loads modules from a config file, which sounds good and may be wanted
456 by some sysadmin, but also means in common configurations that GNOME keyring
457 environment variables are used and so breaks for users calling mailq.
458 To prevent this, we init PKCS11 first, which is the documented approach. */
460 if (!gnutls_allow_auto_pkcs11)
461 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
462 return tls_error_gnu(NULL, US"gnutls_pkcs11_init", rc, errstr);
465 #ifndef GNUTLS_AUTO_GLOBAL_INIT
466 if ((rc = gnutls_global_init()))
467 return tls_error_gnu(NULL, US"gnutls_global_init", rc, errstr);
470 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
473 gnutls_global_set_log_function(exim_gnutls_logger_cb);
474 /* arbitrarily chosen level; bump up to 9 for more */
475 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
480 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
481 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
484 exim_gnutls_base_init_done = TRUE;
490 /* Daemon-call before each connection. Nothing to do for GnuTLS. */
493 tls_per_lib_daemon_tick(void)
497 /* Daemon one-time initialisation */
500 tls_per_lib_daemon_init(void)
502 uschar * dummy_errstr;
503 static BOOL once = FALSE;
505 if (!exim_gnutls_base_init_done)
506 tls_g_init(&dummy_errstr);
512 #ifdef EXIM_HAVE_TLS_RESUME
513 /* We are dependent on the GnuTLS implementation of the Session Ticket
514 encryption; both the strength and the key rotation period. We hope that
515 the strength at least matches that of the ciphersuite (but GnuTLS does not
518 gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
519 if (f.running_in_test_harness) ssl_session_timeout = 6;
522 tls_daemon_creds_reload();
526 /* ------------------------------------------------------------------------ */
528 /*************************************************
529 * Deal with logging errors during I/O *
530 *************************************************/
532 /* We have to get the identity of the peer from saved data.
535 state the current GnuTLS exim state container
536 rc the GnuTLS error code, or 0 if it's a local error
537 when text identifying read or write
538 text local error text when rc is 0
544 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
549 msg = rc == GNUTLS_E_FATAL_ALERT_RECEIVED
550 ? string_sprintf("A TLS fatal alert has been received: %s",
551 US gnutls_alert_get_name(gnutls_alert_get(state->session)))
552 #ifdef GNUTLS_E_PREMATURE_TERMINATION
553 : rc == GNUTLS_E_PREMATURE_TERMINATION && errno
554 ? string_sprintf("%s: syscall: %s", US gnutls_strerror(rc), strerror(errno))
556 : US gnutls_strerror(rc);
558 (void) tls_error(when, msg, state->host, &errstr);
561 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
562 state->host->name, state->host->address, errstr);
565 uschar * conn_info = smtp_get_connection_info();
566 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
567 /* I'd like to get separated H= here, but too hard for now */
568 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
575 /*************************************************
576 * Set various Exim expansion vars *
577 *************************************************/
579 #define exim_gnutls_cert_err(Label) \
582 if (rc != GNUTLS_E_SUCCESS) \
584 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
585 (Label), gnutls_strerror(rc)); \
591 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
595 rc = gnutls_x509_crt_init(crtp);
596 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
598 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
599 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
604 #undef exim_gnutls_cert_err
607 /* We set various Exim global variables from the state, once a session has
608 been established. With TLS callouts, may need to change this to stack
609 variables, or just re-call it with the server state after client callout
612 Make sure anything set here is unset in tls_getc().
616 tls_bits strength indicator
617 tls_certificate_verified bool indicator
618 tls_channelbinding for some SASL mechanisms
621 tls_peercert pointer to library internal
623 tls_sni a (UTF-8) string
624 tls_ourcert pointer to library internal
627 state the relevant exim_gnutls_state_st *
631 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
633 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
636 gnutls_datum_t channel;
638 tls_support * tlsp = state->tlsp;
640 tlsp->active.sock = state->fd_out;
641 tlsp->active.tls_ctx = state;
643 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
645 tlsp->certificate_verified = state->peer_cert_verified;
647 tlsp->dane_verified = state->peer_dane_verified;
650 /* note that tls_channelbinding is not saved to the spool file, since it's
651 only available for use for authenticators while this TLS session is running. */
653 tlsp->channelbinding = NULL;
654 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
657 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
658 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
661 /* Declare the taintedness of the binding info. On server, untainted; on
662 client, tainted - being the Finish msg from the server. */
664 old_pool = store_pool;
665 store_pool = POOL_PERM;
666 tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
668 store_pool = old_pool;
669 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
673 /* peercert is set in peer_status() */
674 tlsp->peerdn = state->peerdn;
676 /* do not corrupt sni sent by client; record sni rxd by server */
678 tlsp->sni = state->received_sni;
680 /* record our certificate */
682 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
683 gnutls_x509_crt_t crt;
685 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
692 #ifndef GNUTLS_AUTO_DHPARAMS
693 /*************************************************
694 * Setup up DH parameters *
695 *************************************************/
697 /* Generating the D-H parameters may take a long time. They only need to
698 be re-generated every so often, depending on security policy. What we do is to
699 keep these parameters in a file in the spool directory. If the file does not
700 exist, we generate them. This means that it is easy to cause a regeneration.
702 The new file is written as a temporary file and renamed, so that an incomplete
703 file is never present. If two processes both compute some new parameters, you
704 waste a bit of effort, but it doesn't seem worth messing around with locking to
707 Returns: OK/DEFER/FAIL
711 init_server_dh(uschar ** errstr)
714 unsigned int dh_bits;
715 gnutls_datum_t m = {.data = NULL, .size = 0};
716 uschar filename_buf[PATH_MAX];
717 uschar *filename = NULL;
719 uschar *exp_tls_dhparam;
720 BOOL use_file_in_spool = FALSE;
721 host_item *host = NULL; /* dummy for macros */
723 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
725 if ((rc = gnutls_dh_params_init(&dh_server_params)))
726 return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
728 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
731 if (!exp_tls_dhparam)
733 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
734 m.data = US std_dh_prime_default();
735 m.size = Ustrlen(m.data);
737 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
738 use_file_in_spool = TRUE;
739 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
741 DEBUG(D_tls) debug_printf("Requested no DH parameters\n");
744 else if (exp_tls_dhparam[0] != '/')
746 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
747 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
748 m.size = Ustrlen(m.data);
751 filename = exp_tls_dhparam;
755 if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
756 return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
757 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
761 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
762 /* If you change this constant, also change dh_param_fn_ext so that we can use a
763 different filename and ensure we have sufficient bits. */
765 if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
766 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
768 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits\n",
771 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
773 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits\n",
777 /* Some clients have hard-coded limits. */
778 if (dh_bits > tls_dh_max_bits)
781 debug_printf("tls_dh_max_bits clamping override, using %d bits instead\n",
783 dh_bits = tls_dh_max_bits;
786 if (use_file_in_spool)
788 if (!string_format(filename_buf, sizeof(filename_buf),
789 "%s/gnutls-params-%d", spool_directory, dh_bits))
790 return tls_error(US"overlong filename", NULL, NULL, errstr);
791 filename = filename_buf;
794 /* Open the cache file for reading and if successful, read it and set up the
797 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
803 if (fstat(fd, &statbuf) < 0) /* EIO */
807 return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
809 if (!S_ISREG(statbuf.st_mode))
812 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
814 if (!(fp = fdopen(fd, "rb")))
818 return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
819 saved_errno, NULL, errstr);
822 m.size = statbuf.st_size;
823 if (!(m.data = store_malloc(m.size)))
826 return tls_error_sys(US"malloc failed", errno, NULL, errstr);
828 if (!(sz = fread(m.data, m.size, 1, fp)))
833 return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
837 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
840 return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
841 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
844 /* If the file does not exist, fall through to compute new data and cache it.
845 If there was any other opening error, it is serious. */
847 else if (errno == ENOENT)
851 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
854 return tls_error(string_open_failed("\"%s\" for reading", filename),
857 /* If ret < 0, either the cache file does not exist, or the data it contains
858 is not useful. One particular case of this is when upgrading from an older
859 release of Exim in which the data was stored in a different format. We don't
860 try to be clever and support both formats; we just regenerate new data in this
866 unsigned int dh_bits_gen = dh_bits;
868 if ((PATH_MAX - Ustrlen(filename)) < 10)
869 return tls_error(US"Filename too long to generate replacement",
870 filename, NULL, errstr);
872 temp_fn = string_copy(US"exim-dh.XXXXXXX");
873 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
874 return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
875 (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
877 /* GnuTLS overshoots! If we ask for 2236, we might get 2237 or more. But
878 there's no way to ask GnuTLS how many bits there really are. We can ask
879 how many bits were used in a TLS session, but that's it! The prime itself
880 is hidden behind too much abstraction. So we ask for less, and proceed on
881 a wing and a prayer. First attempt, subtracted 3 for 2233 and got 2240. */
883 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
885 dh_bits_gen = dh_bits - 10;
887 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
892 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
894 if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
895 return tls_error_gnu(NULL, US"gnutls_dh_params_generate2", rc, errstr);
897 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
898 and I confirmed that a NULL call to get the size first is how the GnuTLS
899 sample apps handle this. */
903 if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
904 GNUTLS_X509_FMT_PEM, m.data, &sz))
905 && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
906 return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3(NULL) sizing",
909 if (!(m.data = store_malloc(m.size)))
910 return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
912 /* this will return a size 1 less than the allocation size above */
913 if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
917 return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3() real", rc, errstr);
919 m.size = sz; /* shrink by 1, probably */
921 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
924 return tls_error_sys(US"TLS cache write D-H params failed",
925 errno, NULL, errstr);
928 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
929 return tls_error_sys(US"TLS cache write D-H params final newline failed",
930 errno, NULL, errstr);
932 if ((rc = close(fd)))
933 return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
935 if (Urename(temp_fn, filename) < 0)
936 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
937 temp_fn, filename), errno, NULL, errstr);
939 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
942 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
950 /* Create and install a selfsigned certificate, for use in server mode. */
953 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
955 gnutls_x509_crt_t cert = NULL;
957 gnutls_x509_privkey_t pkey = NULL;
958 const uschar * where;
961 #ifndef SUPPORT_SELFSIGN
962 where = US"library too old";
963 rc = GNUTLS_E_NO_CERTIFICATE_FOUND;
967 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
968 where = US"initialising pkey";
969 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
971 where = US"initialising cert";
972 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
974 where = US"generating pkey"; /* Hangs on 2.12.23 */
975 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
976 #ifdef SUPPORT_PARAM_TO_PK_BITS
977 # ifndef GNUTLS_SEC_PARAM_MEDIUM
978 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
980 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
987 where = US"configuring cert";
989 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
990 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
991 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
992 || (rc = gnutls_x509_crt_set_expiration_time(cert, (long)2 * 60 * 60)) /* 2 hour */
993 || (rc = gnutls_x509_crt_set_key(cert, pkey))
995 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
996 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
997 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
998 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
999 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
1000 GNUTLS_OID_X520_COMMON_NAME, 0,
1001 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
1005 where = US"signing cert";
1006 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
1008 where = US"installing selfsign cert";
1010 if ((rc = gnutls_certificate_set_x509_key(state->lib_state.x509_cred,
1017 if (cert) gnutls_x509_crt_deinit(cert);
1018 if (pkey) gnutls_x509_privkey_deinit(pkey);
1022 rc = tls_error_gnu(state, where, rc, errstr);
1029 /* Add certificate and key, from files.
1032 Zero or negative: good. Negate value for certificate index if < 0.
1033 Greater than zero: FAIL or DEFER code.
1037 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
1038 const uschar * certfile, const uschar * keyfile, uschar ** errstr)
1040 int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
1041 CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
1043 return tls_error_gnu(state,
1044 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
1050 #if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1051 /* Load an OCSP proof from file for sending by the server. Called
1052 on getting a status-request handshake message, for earlier versions
1056 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
1057 gnutls_datum_t * ocsp_response)
1060 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
1062 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
1064 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
1066 tls_in.ocsp = OCSP_NOT_RESP;
1067 return GNUTLS_E_NO_CERTIFICATE_STATUS;
1070 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1076 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1077 /* Make a note that we saw a status-request */
1079 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
1080 const uschar * data, unsigned size)
1082 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1085 case 5: /* Status Request */
1086 DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
1087 tls_in.ocsp = OCSP_NOT_RESP;
1089 #ifdef EXIM_HAVE_ALPN
1090 case 16: /* Application Layer Protocol Notification */
1091 /* The format of "data" here doesn't seem to be documented, but appears
1092 to be a 2-byte field with a (redundant, given the "size" arg) total length
1093 then a sequence of one-byte size then string (not nul-term) names. The
1094 latter is as described in OpenSSL documentation. */
1096 DEBUG(D_tls) debug_printf("Seen ALPN extension from client (s=%u):", size);
1097 for (const uschar * s = data+2; s-data < size-1; s += *s + 1)
1100 DEBUG(D_tls) debug_printf(" '%.*s'", (int)*s, s+1);
1102 DEBUG(D_tls) debug_printf("\n");
1103 if (server_seen_alpn > 1)
1105 DEBUG(D_tls) debug_printf("TLS: too many ALPNs presented in handshake\n");
1106 return GNUTLS_E_NO_APPLICATION_PROTOCOL;
1114 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
1116 tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
1117 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1119 /* Call fn for each extension seen. 3.6.3 onwards */
1120 return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
1121 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
1125 # ifdef notdef_crashes
1126 /* Make a note that we saw a status-response */
1128 tls_server_servercerts_ext(void * ctx, unsigned tls_id,
1129 const unsigned char *data, unsigned size)
1131 /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
1132 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1133 if (FALSE && tls_id == 5) /* status_request */
1135 DEBUG(D_tls) debug_printf("Seen status_request extension\n");
1136 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1137 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1143 /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
1145 tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
1146 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1148 /* Call fn for each extension seen. 3.6.3 onwards */
1149 # ifdef notdef_crashes
1151 return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
1154 #endif /*SUPPORT_GNUTLS_EXT_RAW_PARSE*/
1156 /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
1157 "Handshake Protocol: Certificate" record.
1158 So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
1160 This is different to tls1.2 - where it is a separate record (wireshark term) / handshake message (gnutls term).
1163 #if defined(EXIM_HAVE_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1164 /* Callback for certificate-status, on server. We sent stapled OCSP. */
1166 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
1167 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1169 DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
1170 # ifdef SUPPORT_SRV_OCSP_STACK
1171 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1172 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1174 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1179 /* Callback for handshake messages, on server */
1181 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
1182 unsigned incoming, const gnutls_datum_t * msg)
1184 /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
1187 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1188 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
1189 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
1190 case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
1191 return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
1193 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
1194 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
1195 # ifdef EXIM_HAVE_TLS_RESUME
1196 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
1197 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
1206 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1208 tls_server_testharness_ocsp_fiddle(void)
1210 extern char ** environ;
1211 if (environ) for (uschar ** p = USS environ; *p; p++)
1212 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1214 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
1215 exim_testharness_disable_ocsp_validity_check = TRUE;
1220 /**************************************************
1221 * One-time init credentials for server and client *
1222 **************************************************/
1225 creds_basic_init(gnutls_certificate_credentials_t x509_cred, BOOL server)
1227 #ifdef SUPPORT_SRV_OCSP_STACK
1228 gnutls_certificate_set_flags(x509_cred, GNUTLS_CERTIFICATE_API_V2);
1230 # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1231 if (server && tls_ocsp_file)
1233 if (f.running_in_test_harness)
1234 tls_server_testharness_ocsp_fiddle();
1236 if (exim_testharness_disable_ocsp_validity_check)
1237 gnutls_certificate_set_flags(x509_cred,
1238 GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
1243 debug_printf("TLS: basic cred init, %s\n", server ? "server" : "client");
1247 creds_load_server_certs(exim_gnutls_state_st * state, const uschar * cert,
1248 const uschar * pkey, const uschar * ocsp, uschar ** errstr)
1250 const uschar * clist = cert;
1251 const uschar * klist = pkey;
1252 const uschar * olist;
1253 int csep = 0, ksep = 0, osep = 0, cnt = 0, rc;
1254 uschar * cfile, * kfile, * ofile;
1255 #ifndef DISABLE_OCSP
1256 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1257 gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
1260 if (!expand_check(ocsp, US"tls_ocsp_file", &ofile, errstr))
1265 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1267 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1268 return tls_error(US"cert/key setup: out of keys", NULL, NULL, errstr);
1269 else if ((rc = tls_add_certfile(state, NULL, cfile, kfile, errstr)) > 0)
1273 int gnutls_cert_index = -rc;
1274 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
1275 gnutls_cert_index, cfile);
1277 #ifndef DISABLE_OCSP
1280 /* Set the OCSP stapling server info */
1281 if (gnutls_buggy_ocsp)
1284 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1286 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1288 DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n",
1289 gnutls_cert_index, ofile);
1290 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1291 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1293 ocsp_fmt = GNUTLS_X509_FMT_PEM;
1296 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1298 ocsp_fmt = GNUTLS_X509_FMT_DER;
1302 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1303 state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
1305 return tls_error_gnu(state,
1306 US"gnutls_certificate_set_ocsp_status_request_file2",
1309 debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
1311 /* Arrange callbacks for OCSP request observability */
1314 gnutls_handshake_set_hook_function(state->session,
1315 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1317 state->lib_state.ocsp_hook = TRUE;
1321 # if defined(SUPPORT_SRV_OCSP_STACK)
1322 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1323 state->lib_state.x509_cred, gnutls_cert_index,
1324 server_ocsp_stapling_cb, ofile)))
1325 return tls_error_gnu(state,
1326 US"gnutls_certificate_set_ocsp_status_request_function2",
1334 debug_printf("oops; multiple OCSP files not supported\n");
1337 gnutls_certificate_set_ocsp_status_request_function(
1338 state->lib_state.x509_cred, server_ocsp_stapling_cb, ofile);
1340 # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
1343 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1345 #endif /* DISABLE_OCSP */
1351 creds_load_client_certs(exim_gnutls_state_st * state, const host_item * host,
1352 const uschar * cert, const uschar * pkey, uschar ** errstr)
1354 int rc = tls_add_certfile(state, host, cert, pkey, errstr);
1355 if (rc > 0) return rc;
1356 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1361 creds_load_cabundle(exim_gnutls_state_st * state, const uschar * bundle,
1362 const host_item * host, uschar ** errstr)
1365 struct stat statbuf;
1367 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1368 if (Ustrcmp(bundle, "system") == 0 || Ustrncmp(bundle, "system,", 7) == 0)
1369 cert_count = gnutls_certificate_set_x509_system_trust(state->lib_state.x509_cred);
1373 if (Ustat(bundle, &statbuf) < 0)
1375 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' "
1376 "(tls_verify_certificates): %s", bundle, strerror(errno));
1380 #ifndef SUPPORT_CA_DIR
1381 /* The test suite passes in /dev/null; we could check for that path explicitly,
1382 but who knows if someone has some weird FIFO which always dumps some certs, or
1383 other weirdness. The thing we really want to check is that it's not a
1384 directory, since while OpenSSL supports that, GnuTLS does not.
1385 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1386 if (S_ISDIR(statbuf.st_mode))
1388 log_write(0, LOG_MAIN|LOG_PANIC,
1389 "tls_verify_certificates \"%s\" is a directory", bundle);
1394 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1395 bundle, statbuf.st_size);
1397 if (statbuf.st_size == 0)
1400 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1406 #ifdef SUPPORT_CA_DIR
1407 (statbuf.st_mode & S_IFMT) == S_IFDIR
1409 gnutls_certificate_set_x509_trust_dir(state->lib_state.x509_cred,
1410 CS bundle, GNUTLS_X509_FMT_PEM)
1413 gnutls_certificate_set_x509_trust_file(state->lib_state.x509_cred,
1414 CS bundle, GNUTLS_X509_FMT_PEM);
1416 #ifdef SUPPORT_CA_DIR
1417 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1418 when using the directory-of-certs config model. */
1420 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1422 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1424 state->lib_state.ca_rdn_emulate = TRUE;
1429 return tls_error_gnu(state, US"setting certificate trust", cert_count, errstr);
1431 debug_printf("Added %d certificate authorities\n", cert_count);
1438 creds_load_crl(exim_gnutls_state_st * state, const uschar * crl, uschar ** errstr)
1441 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
1442 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
1443 CS crl, GNUTLS_X509_FMT_PEM)) < 0)
1444 return tls_error_gnu(state, US"gnutls_certificate_set_x509_crl_file",
1445 cert_count, errstr);
1447 DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
1453 creds_load_pristring(exim_gnutls_state_st * state, const uschar * p,
1454 const char ** errpos)
1458 p = exim_default_gnutls_priority;
1460 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1462 return gnutls_priority_init( (gnutls_priority_t *) &state->lib_state.pri_cache,
1467 tls_server_creds_init(void)
1469 uschar * dummy_errstr;
1470 unsigned lifetime = 0;
1472 state_server.lib_state = null_tls_preload;
1473 if (gnutls_certificate_allocate_credentials(
1474 (gnutls_certificate_credentials_t *) &state_server.lib_state.x509_cred))
1476 state_server.lib_state.x509_cred = NULL;
1479 creds_basic_init(state_server.lib_state.x509_cred, TRUE);
1481 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1482 /* If tls_certificate has any $ indicating expansions, it is not good.
1483 If tls_privatekey is set but has $, not good. Likewise for tls_ocsp_file.
1484 If all good (and tls_certificate set), load the cert(s). */
1486 if ( opt_set_and_noexpand(tls_certificate)
1487 # ifndef DISABLE_OCSP
1488 && opt_unset_or_noexpand(tls_ocsp_file)
1490 && opt_unset_or_noexpand(tls_privatekey))
1492 /* Set watches on the filenames. The implementation does de-duplication
1493 so we can just blindly do them all.
1496 if ( tls_set_watch(tls_certificate, TRUE)
1497 # ifndef DISABLE_OCSP
1498 && tls_set_watch(tls_ocsp_file, TRUE)
1500 && tls_set_watch(tls_privatekey, TRUE))
1502 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1503 if (creds_load_server_certs(&state_server, tls_certificate,
1504 tls_privatekey && *tls_privatekey ? tls_privatekey : tls_certificate,
1505 # ifdef DISABLE_OCSP
1510 &dummy_errstr) == 0)
1511 state_server.lib_state.conn_certs = TRUE;
1514 else if ( !tls_certificate && !tls_privatekey
1515 # ifndef DISABLE_OCSP
1519 { /* Generate & preload a selfsigned cert. No files to watch. */
1520 if ((tls_install_selfsign(&state_server, &dummy_errstr)) == OK)
1522 state_server.lib_state.conn_certs = TRUE;
1523 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1527 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1529 /* If tls_verify_certificates is non-empty and has no $, load CAs.
1530 If none was configured and we can't handle "system", treat as empty. */
1532 if ( opt_set_and_noexpand(tls_verify_certificates)
1533 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1534 && Ustrcmp(tls_verify_certificates, "system") != 0
1538 if (tls_set_watch(tls_verify_certificates, FALSE))
1540 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1541 if (creds_load_cabundle(&state_server, tls_verify_certificates,
1542 NULL, &dummy_errstr) != OK)
1544 state_server.lib_state.cabundle = TRUE;
1546 /* If CAs loaded and tls_crl is non-empty and has no $, load it */
1548 if (opt_set_and_noexpand(tls_crl))
1550 if (tls_set_watch(tls_crl, FALSE))
1552 DEBUG(D_tls) debug_printf("TLS: preloading CRL for server\n");
1553 if (creds_load_crl(&state_server, tls_crl, &dummy_errstr) != OK)
1555 state_server.lib_state.crl = TRUE;
1559 DEBUG(D_tls) debug_printf("TLS: not preloading CRL for server\n");
1563 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1564 #endif /* EXIM_HAVE_INOTIFY */
1566 /* If tls_require_ciphers is non-empty and has no $, load the
1567 ciphers priority cache. If unset, load with the default.
1568 (server-only as the client one depends on non/DANE) */
1570 if (!tls_require_ciphers || opt_set_and_noexpand(tls_require_ciphers))
1572 const char * dummy_errpos;
1573 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server: %s\n",
1574 tls_require_ciphers);
1575 if ( creds_load_pristring(&state_server, tls_require_ciphers, &dummy_errpos)
1577 state_server.lib_state.pri_string = TRUE;
1580 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1585 /* Preload whatever creds are static, onto a transport. The client can then
1586 just copy the pointer as it starts up. */
1589 tls_client_creds_init(transport_instance * t, BOOL watch)
1591 smtp_transport_options_block * ob = t->options_block;
1592 exim_gnutls_state_st tpt_dummy_state;
1593 host_item * dummy_host = (host_item *)1;
1594 uschar * dummy_errstr;
1596 if ( !exim_gnutls_base_init_done
1597 && tls_g_init(&dummy_errstr) != OK)
1600 ob->tls_preload = null_tls_preload;
1601 if (gnutls_certificate_allocate_credentials(
1602 (struct gnutls_certificate_credentials_st **)&ob->tls_preload.x509_cred))
1604 ob->tls_preload.x509_cred = NULL;
1607 creds_basic_init(ob->tls_preload.x509_cred, FALSE);
1609 tpt_dummy_state.session = NULL;
1610 tpt_dummy_state.lib_state = ob->tls_preload;
1612 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1613 if ( opt_set_and_noexpand(ob->tls_certificate)
1614 && opt_unset_or_noexpand(ob->tls_privatekey))
1617 || ( tls_set_watch(ob->tls_certificate, FALSE)
1618 && tls_set_watch(ob->tls_privatekey, FALSE)
1621 const uschar * pkey = ob->tls_privatekey;
1624 debug_printf("TLS: preloading client certs for transport '%s'\n", t->name);
1626 /* The state->lib_state.x509_cred is used for the certs load, and is the sole
1627 structure element used. So we can set up a dummy. The hoat arg only
1628 selects a retcode in case of fail, so any value */
1630 if (creds_load_client_certs(&tpt_dummy_state, dummy_host,
1631 ob->tls_certificate, pkey ? pkey : ob->tls_certificate,
1632 &dummy_errstr) == OK)
1633 ob->tls_preload.conn_certs = TRUE;
1638 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1640 /* If tls_verify_certificates is non-empty and has no $, load CAs.
1641 If none was configured and we can't handle "system", treat as empty. */
1643 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1644 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1645 && Ustrcmp(ob->tls_verify_certificates, "system") != 0
1649 if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
1652 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1653 if (creds_load_cabundle(&tpt_dummy_state, ob->tls_verify_certificates,
1654 dummy_host, &dummy_errstr) != OK)
1656 ob->tls_preload.cabundle = TRUE;
1658 if (opt_set_and_noexpand(ob->tls_crl))
1660 if (!watch || tls_set_watch(ob->tls_crl, FALSE))
1662 DEBUG(D_tls) debug_printf("TLS: preloading CRL for transport '%s'\n", t->name);
1663 if (creds_load_crl(&tpt_dummy_state, ob->tls_crl, &dummy_errstr) != OK)
1665 ob->tls_preload.crl = TRUE;
1669 DEBUG(D_tls) debug_printf("TLS: not preloading CRL, for transport '%s'\n", t->name);
1674 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1676 /* We do not preload tls_require_ciphers to to the transport as it implicitly
1677 depends on DANE or plain usage. */
1683 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1684 /* Invalidate the creds cached, by dropping the current ones.
1685 Call when we notice one of the source files has changed. */
1688 tls_server_creds_invalidate(void)
1690 if (state_server.lib_state.pri_cache)
1691 gnutls_priority_deinit(state_server.lib_state.pri_cache);
1692 state_server.lib_state.pri_cache = NULL;
1694 if (state_server.lib_state.x509_cred)
1695 gnutls_certificate_free_credentials(state_server.lib_state.x509_cred);
1696 state_server.lib_state = null_tls_preload;
1701 tls_client_creds_invalidate(transport_instance * t)
1703 smtp_transport_options_block * ob = t->options_block;
1704 if (ob->tls_preload.x509_cred)
1705 gnutls_certificate_free_credentials(ob->tls_preload.x509_cred);
1706 ob->tls_preload = null_tls_preload;
1711 /*************************************************
1712 * Variables re-expanded post-SNI *
1713 *************************************************/
1715 /* Called from both server and client code, via tls_init(), and also from
1716 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
1718 We can tell the two apart by state->received_sni being non-NULL in callback.
1720 The callback should not call us unless state->trigger_sni_changes is true,
1721 which we are responsible for setting on the first pass through.
1724 state exim_gnutls_state_st *
1725 errstr error string pointer
1727 Returns: OK/DEFER/FAIL
1731 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
1734 const host_item *host = state->host; /* macro should be reconsidered? */
1735 const uschar *saved_tls_certificate = NULL;
1736 const uschar *saved_tls_privatekey = NULL;
1737 const uschar *saved_tls_verify_certificates = NULL;
1738 const uschar *saved_tls_crl = NULL;
1741 /* We check for tls_sni *before* expansion. */
1742 if (!host) /* server */
1743 if (!state->received_sni)
1745 if ( state->tls_certificate
1746 && ( Ustrstr(state->tls_certificate, US"tls_sni")
1747 || Ustrstr(state->tls_certificate, US"tls_in_sni")
1748 || Ustrstr(state->tls_certificate, US"tls_out_sni")
1751 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI\n");
1752 state->trigger_sni_changes = TRUE;
1755 else /* SNI callback case */
1757 /* useful for debugging */
1758 saved_tls_certificate = state->exp_tls_certificate;
1759 saved_tls_privatekey = state->exp_tls_privatekey;
1760 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1761 saved_tls_crl = state->exp_tls_crl;
1764 if (!state->lib_state.x509_cred)
1766 if ((rc = gnutls_certificate_allocate_credentials(
1767 (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))
1768 return tls_error_gnu(state, US"gnutls_certificate_allocate_credentials",
1770 creds_basic_init(state->lib_state.x509_cred, !host);
1774 /* remember: Expand_check_tlsvar() is expand_check() but fiddling with
1775 state members, assuming consistent naming; and expand_check() returns
1776 false if expansion failed, unless expansion was forced to fail. */
1778 /* check if we at least have a certificate, before doing expensive
1781 if (!state->lib_state.conn_certs)
1783 if (!Expand_check_tlsvar(tls_certificate, errstr))
1786 /* certificate is mandatory in server, optional in client */
1788 if ( !state->exp_tls_certificate
1789 || !*state->exp_tls_certificate
1792 return tls_install_selfsign(state, errstr);
1794 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1796 if (state->tls_privatekey && !Expand_check_tlsvar(tls_privatekey, errstr))
1799 /* tls_privatekey is optional, defaulting to same file as certificate */
1801 if (!state->tls_privatekey || !*state->tls_privatekey)
1803 state->tls_privatekey = state->tls_certificate;
1804 state->exp_tls_privatekey = state->exp_tls_certificate;
1807 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1810 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1811 state->exp_tls_certificate, state->exp_tls_privatekey);
1813 if (state->received_sni)
1814 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1815 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1818 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1819 load = FALSE; /* avoid re-loading the same certs */
1821 else /* unload the pre-SNI certs before loading new ones */
1823 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair\n");
1824 gnutls_certificate_free_keys(state->lib_state.x509_cred);
1829 ? creds_load_client_certs(state, host, state->exp_tls_certificate,
1830 state->exp_tls_privatekey, errstr)
1831 : creds_load_server_certs(state, state->exp_tls_certificate,
1832 state->exp_tls_privatekey,
1845 debug_printf("%s certs were preloaded\n", host ? "client" : "server");
1847 if (!state->tls_privatekey) state->tls_privatekey = state->tls_certificate;
1848 state->exp_tls_certificate = US state->tls_certificate;
1849 state->exp_tls_privatekey = US state->tls_privatekey;
1851 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1852 if (state->lib_state.ocsp_hook)
1853 gnutls_handshake_set_hook_function(state->session,
1854 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1859 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1860 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1861 error message is provided. However, if we just refrain from setting anything up
1862 in that case, certificate verification fails, which seems to be the correct
1864 If none was configured and we can't handle "system", treat as empty. */
1866 if (!state->lib_state.cabundle)
1868 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1870 if (!Expand_check_tlsvar(tls_verify_certificates, errstr))
1872 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1873 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1874 state->exp_tls_verify_certificates = NULL;
1876 if (state->tls_crl && *state->tls_crl)
1877 if (!Expand_check_tlsvar(tls_crl, errstr))
1880 if (!(state->exp_tls_verify_certificates &&
1881 *state->exp_tls_verify_certificates))
1884 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1885 /* With no tls_verify_certificates, we ignore tls_crl too */
1892 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1895 rc = creds_load_cabundle(state, state->exp_tls_verify_certificates, host, errstr);
1896 if (rc != OK) return rc;
1901 debug_printf("%s CA bundle was preloaded\n", host ? "client" : "server");
1902 state->exp_tls_verify_certificates = US state->tls_verify_certificates;
1904 #ifdef SUPPORT_CA_DIR
1905 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1906 when using the directory-of-certs config model. */
1907 if (state->lib_state.ca_rdn_emulate)
1908 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1913 if (!state->lib_state.crl)
1915 if ( state->tls_crl && *state->tls_crl
1916 && state->exp_tls_crl && *state->exp_tls_crl)
1917 return creds_load_crl(state, state->exp_tls_crl, errstr);
1922 debug_printf("%s CRL was preloaded\n", host ? "client" : "server");
1923 state->exp_tls_crl = US state->tls_crl;
1932 /*************************************************
1933 * Set X.509 state variables *
1934 *************************************************/
1936 /* In GnuTLS, the registered cert/key are not replaced by a later
1937 set of a cert/key, so for SNI support we need a whole new x509_cred
1938 structure. Which means various other non-re-expanded pieces of state
1939 need to be re-set in the new struct, so the setting logic is pulled
1943 state exim_gnutls_state_st *
1944 errstr error string pointer
1946 Returns: OK/DEFER/FAIL
1950 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1953 const host_item *host = state->host; /* macro should be reconsidered? */
1955 #ifndef GNUTLS_AUTO_DHPARAMS
1956 /* Create D-H parameters, or read them from the cache file. This function does
1957 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1958 client-side params. */
1962 if (!dh_server_params)
1963 if ((rc = init_server_dh(errstr)) != OK) return rc;
1965 /* Unnecessary & discouraged with 3.6.0 or later */
1966 gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
1970 /* Link the credentials to the session. */
1972 if ((rc = gnutls_credentials_set(state->session,
1973 GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))
1974 return tls_error_gnu(state, US"gnutls_credentials_set", rc, errstr);
1979 /*************************************************
1980 * Initialize for GnuTLS *
1981 *************************************************/
1984 /* Called from both server and client code. In the case of a server, errors
1985 before actual TLS negotiation return DEFER.
1988 host connected host, if client; NULL if server
1989 ob tranport options block, if client; NULL if server
1990 require_ciphers tls_require_ciphers setting
1991 caller_state returned state-info structure
1992 errstr error string pointer
1994 Returns: OK/DEFER/FAIL
1999 const host_item *host,
2000 smtp_transport_options_block * ob,
2001 const uschar * require_ciphers,
2002 exim_gnutls_state_st **caller_state,
2006 exim_gnutls_state_st * state;
2010 if ( !exim_gnutls_base_init_done
2011 && (rc = tls_g_init(errstr)) != OK)
2016 /* For client-side sessions we allocate a context. This lets us run
2017 several in parallel. */
2019 int old_pool = store_pool;
2020 store_pool = POOL_PERM;
2021 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
2022 store_pool = old_pool;
2024 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2025 state->lib_state = ob->tls_preload;
2027 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
2028 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
2030 state->tls_certificate = ob->tls_certificate;
2031 state->tls_privatekey = ob->tls_privatekey;
2032 state->tls_sni = ob->tls_sni;
2033 state->tls_verify_certificates = ob->tls_verify_certificates;
2034 state->tls_crl = ob->tls_crl;
2038 /* Server operations always use the one state_server context. It is not
2039 shared because we have forked a fresh process for every receive. However it
2040 can get re-used for successive TLS sessions on a single TCP connection. */
2042 state = &state_server;
2044 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
2045 rc = gnutls_init(&state->session, GNUTLS_SERVER);
2047 state->tls_certificate = tls_certificate;
2048 state->tls_privatekey = tls_privatekey;
2049 state->tls_sni = NULL;
2050 state->tls_verify_certificates = tls_verify_certificates;
2051 state->tls_crl = tls_crl;
2054 return tls_error_gnu(state, US"gnutls_init", rc, errstr);
2056 state->tls_require_ciphers = require_ciphers;
2059 /* This handles the variables that might get re-expanded after TLS SNI;
2060 tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
2063 debug_printf("Expanding various TLS configuration options for session credentials\n");
2064 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
2066 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
2067 requires a new structure afterwards. */
2069 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
2071 /* set SNI in client, only */
2074 if (!expand_check(state->tls_sni, US"tls_out_sni", &state->tlsp->sni, errstr))
2076 if (state->tlsp->sni && *state->tlsp->sni)
2079 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
2080 sz = Ustrlen(state->tlsp->sni);
2081 if ((rc = gnutls_server_name_set(state->session,
2082 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
2083 return tls_error_gnu(state, US"gnutls_server_name_set", rc, errstr);
2086 else if (state->tls_sni)
2087 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
2088 "have an SNI set for a server [%s]\n", state->tls_sni);
2090 if (!state->lib_state.pri_string)
2092 const uschar * p = NULL;
2093 const char * errpos;
2095 /* This is the priority string support,
2096 http://www.gnutls.org/manual/html_node/Priority-Strings.html
2097 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
2098 This was backwards incompatible, but means Exim no longer needs to track
2099 all algorithms and provide string forms for them. */
2101 if (state->tls_require_ciphers && *state->tls_require_ciphers)
2103 if (!Expand_check_tlsvar(tls_require_ciphers, errstr))
2105 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
2107 p = state->exp_tls_require_ciphers;
2108 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
2112 if ((rc = creds_load_pristring(state, p, &errpos)))
2113 return tls_error_gnu(state, string_sprintf(
2114 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
2115 p, errpos - CS p, errpos),
2120 DEBUG(D_tls) debug_printf("cipher list preloaded\n");
2121 state->exp_tls_require_ciphers = US state->tls_require_ciphers;
2125 if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))
2126 return tls_error_gnu(state, US"gnutls_priority_set", rc, errstr);
2128 /* This also sets the server ticket expiration time to the same, and
2129 the STEK rotation time to 3x. */
2131 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
2133 /* Reduce security in favour of increased compatibility, if the admin
2134 decides to make that trade-off. */
2135 if (gnutls_compat_mode)
2137 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
2138 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
2139 gnutls_session_enable_compatibility_mode(state->session);
2141 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
2145 *caller_state = state;
2151 /*************************************************
2152 * Extract peer information *
2153 *************************************************/
2155 static const uschar *
2156 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
2157 gnutls_mac_algorithm_t mac)
2160 gnutls_kx_algorithm_t kx_i;
2161 gnutls_cipher_algorithm_t cipher_i;
2162 gnutls_mac_algorithm_t mac_i;
2165 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
2167 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
2168 return cipher_stdname(cs_id[0], cs_id[1]);
2174 /* Called from both server and client code.
2175 Only this is allowed to set state->peerdn and state->have_set_peerdn
2176 and we use that to detect double-calls.
2178 NOTE: the state blocks last while the TLS connection is up, which is fine
2179 for logging in the server side, but for the client side, we log after teardown
2180 in src/deliver.c. While the session is up, we can twist about states and
2181 repoint tls_* globals, but those variables used for logging or other variable
2182 expansion that happens _after_ delivery need to have a longer life-time.
2184 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
2185 doing this more than once per generation of a state context. We set them in
2186 the state context, and repoint tls_* to them. After the state goes away, the
2187 tls_* copies of the pointers remain valid and client delivery logging is happy.
2189 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
2193 state exim_gnutls_state_st *
2194 errstr pointer to error string
2196 Returns: OK/DEFER/FAIL
2200 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
2202 gnutls_session_t session = state->session;
2203 const gnutls_datum_t * cert_list;
2205 unsigned int cert_list_size = 0;
2206 gnutls_protocol_t protocol;
2207 gnutls_cipher_algorithm_t cipher;
2208 gnutls_kx_algorithm_t kx;
2209 gnutls_mac_algorithm_t mac;
2210 gnutls_certificate_type_t ct;
2211 gnutls_x509_crt_t crt;
2215 if (state->have_set_peerdn)
2217 state->have_set_peerdn = TRUE;
2219 state->peerdn = NULL;
2222 cipher = gnutls_cipher_get(session);
2223 protocol = gnutls_protocol_get_version(session);
2224 mac = gnutls_mac_get(session);
2226 #ifdef GNUTLS_TLS1_3
2227 protocol >= GNUTLS_TLS1_3 ? 0 :
2229 gnutls_kx_get(session);
2231 old_pool = store_pool;
2233 tls_support * tlsp = state->tlsp;
2234 store_pool = POOL_PERM;
2236 #ifdef SUPPORT_GNUTLS_SESS_DESC
2239 uschar * s = US gnutls_session_get_desc(session), c;
2241 /* Nikos M suggests we use this by preference. It returns like:
2242 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
2244 For partial back-compat, put a colon after the TLS version, replace the
2245 )-( grouping with __, replace in-group - with _ and append the :keysize. */
2247 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
2249 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
2251 tlsp->ver = string_copyn(g->s, g->ptr);
2252 for (uschar * p = US tlsp->ver; *p; p++)
2253 if (*p == '-') { *p = '\0'; break; } /* TLS1.0-PKIX -> TLS1.0 */
2255 g = string_catn(g, US":", 1);
2256 if (*s) s++; /* now on _ between groups */
2259 for (*++s && ++s; (c = *s) && c != ')'; s++)
2260 g = string_catn(g, c == '-' ? US"_" : s, 1);
2261 /* now on ) closing group */
2262 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
2263 /* now on _ between groups */
2265 g = string_catn(g, US":", 1);
2266 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
2267 state->ciphersuite = string_from_gstring(g);
2270 state->ciphersuite = string_sprintf("%s:%s:%d",
2271 gnutls_protocol_get_name(protocol),
2272 gnutls_cipher_suite_get_name(kx, cipher, mac),
2273 (int) gnutls_cipher_get_key_size(cipher) * 8);
2275 /* I don't see a way that spaces could occur, in the current GnuTLS
2276 code base, but it was a concern in the old code and perhaps older GnuTLS
2277 releases did return "TLS 1.0"; play it safe, just in case. */
2279 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
2280 tlsp->ver = string_copyn(state->ciphersuite,
2281 Ustrchr(state->ciphersuite, ':') - state->ciphersuite);
2284 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
2286 tlsp->cipher = state->ciphersuite;
2287 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
2289 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
2291 store_pool = old_pool;
2294 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
2296 if (!cert_list || cert_list_size == 0)
2298 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
2299 cert_list, cert_list_size);
2300 if (state->verify_requirement >= VERIFY_REQUIRED)
2301 return tls_error(US"certificate verification failed",
2302 US"no certificate received from peer", state->host, errstr);
2306 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
2308 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
2310 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
2311 if (state->verify_requirement >= VERIFY_REQUIRED)
2312 return tls_error(US"certificate verification not possible, unhandled type",
2313 ctn, state->host, errstr);
2317 #define exim_gnutls_peer_err(Label) \
2319 if (rc != GNUTLS_E_SUCCESS) \
2321 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
2322 (Label), gnutls_strerror(rc)); \
2323 if (state->verify_requirement >= VERIFY_REQUIRED) \
2324 return tls_error_gnu(state, (Label), rc, errstr); \
2329 rc = import_cert(&cert_list[0], &crt);
2330 exim_gnutls_peer_err(US"cert 0");
2332 state->tlsp->peercert = state->peercert = crt;
2335 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
2336 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
2338 exim_gnutls_peer_err(US"getting size for cert DN failed");
2339 return FAIL; /* should not happen */
2341 dn_buf = store_get_perm(sz, TRUE); /* tainted */
2342 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
2343 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
2345 state->peerdn = dn_buf;
2348 #undef exim_gnutls_peer_err
2354 /*************************************************
2355 * Verify peer certificate *
2356 *************************************************/
2358 /* Called from both server and client code.
2359 *Should* be using a callback registered with
2360 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
2361 the peer information, but that's too new for some OSes.
2364 state exim_gnutls_state_st *
2365 errstr where to put an error message
2368 FALSE if the session should be rejected
2369 TRUE if the cert is okay or we just don't care
2373 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
2378 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
2380 rc = peer_status(state, errstr);
2382 if (state->verify_requirement == VERIFY_NONE)
2385 if (rc != OK || !state->peerdn)
2387 verify = GNUTLS_CERT_INVALID;
2388 *errstr = US"certificate not supplied";
2394 if (state->verify_requirement == VERIFY_DANE && state->host)
2396 /* Using dane_verify_session_crt() would be easy, as it does it all for us
2397 including talking to a DNS resolver. But we want to do that bit ourselves
2398 as the testsuite intercepts and fakes its own DNS environment. */
2403 const gnutls_datum_t * certlist =
2404 gnutls_certificate_get_peers(state->session, &lsize);
2405 int usage = tls_out.tlsa_usage;
2407 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2408 /* Split the TLSA records into two sets, TA and EE selectors. Run the
2409 dane-verification separately so that we know which selector verified;
2410 then we know whether to do name-verification (needed for TA but not EE). */
2412 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
2413 { /* a mixed-usage bundle */
2418 for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
2421 dd = store_get(nrec * sizeof(uschar *), FALSE);
2422 ddl = store_get(nrec * sizeof(int), FALSE);
2425 if ((rc = dane_state_init(&s, 0)))
2428 for (usage = DANESSL_USAGE_DANE_EE;
2429 usage >= DANESSL_USAGE_DANE_TA; usage--)
2430 { /* take records with this usage */
2431 for (j = i = 0; i < nrec; i++)
2432 if (state->dane_data[i][0] == usage)
2434 dd[j] = state->dane_data[i];
2435 ddl[j++] = state->dane_data_len[i];
2442 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
2445 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
2446 gnutls_certificate_type_get(state->session),
2448 usage == DANESSL_USAGE_DANE_EE
2449 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2453 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
2455 else if (verify == 0) /* verification passed */
2463 if (rc) goto tlsa_prob;
2468 if ( (rc = dane_state_init(&s, 0))
2469 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
2471 || (rc = dane_verify_crt_raw(s, certlist, lsize,
2472 gnutls_certificate_type_get(state->session),
2474 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2475 usage == (1 << DANESSL_USAGE_DANE_EE)
2476 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2485 if (verify != 0) /* verification failed */
2488 (void) dane_verification_status_print(verify, &str, 0);
2489 *errstr = US str.data; /* don't bother to free */
2493 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2494 /* If a TA-mode TLSA record was used for verification we must additionally
2495 verify the cert name (but not the CA chain). For EE-mode, skip it. */
2497 if (usage & (1 << DANESSL_USAGE_DANE_EE))
2500 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2503 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2504 /* Assume that the name on the A-record is the one that should be matching
2505 the cert. An alternate view is that the domain part of the email address
2506 is also permissible. */
2508 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2509 CS state->host->name))
2511 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2516 #endif /*SUPPORT_DANE*/
2518 rc = gnutls_certificate_verify_peers2(state->session, &verify);
2521 /* Handle the result of verification. INVALID is set if any others are. */
2523 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
2525 state->peer_cert_verified = FALSE;
2528 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
2533 if (gnutls_certificate_verification_status_print(verify,
2534 gnutls_certificate_type_get(state->session), &txt, 0)
2535 == GNUTLS_E_SUCCESS)
2537 debug_printf("%s\n", txt.data);
2538 gnutls_free(txt.data);
2542 *errstr = verify & GNUTLS_CERT_REVOKED
2543 ? US"certificate revoked" : US"certificate invalid";
2547 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
2548 *errstr, state->peerdn ? state->peerdn : US"<unset>");
2550 if (state->verify_requirement >= VERIFY_REQUIRED)
2553 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
2558 /* Client side, check the server's certificate name versus the name on the
2559 A-record for the connection we made. What to do for server side - what name
2560 to use for client? We document that there is no such checking for server
2563 if ( state->exp_tls_verify_cert_hostnames
2564 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2565 CS state->exp_tls_verify_cert_hostnames)
2569 debug_printf("TLS certificate verification failed: cert name mismatch\n");
2570 if (state->verify_requirement >= VERIFY_REQUIRED)
2575 state->peer_cert_verified = TRUE;
2576 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
2577 state->peerdn ? state->peerdn : US"<unset>");
2581 state->tlsp->peerdn = state->peerdn;
2586 *errstr = string_sprintf("TLSA record problem: %s",
2587 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
2591 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
2598 /* ------------------------------------------------------------------------ */
2601 /* Logging function which can be registered with
2602 * gnutls_global_set_log_function()
2603 * gnutls_global_set_log_level() 0..9
2605 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2607 exim_gnutls_logger_cb(int level, const char *message)
2609 size_t len = strlen(message);
2612 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2615 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2616 message[len-1] == '\n' ? "" : "\n");
2621 /* Called after client hello, should handle SNI work.
2622 This will always set tls_sni (state->received_sni) if available,
2623 and may trigger presenting different certificates,
2624 if state->trigger_sni_changes is TRUE.
2626 Should be registered with
2627 gnutls_handshake_set_post_client_hello_function()
2629 "This callback must return 0 on success or a gnutls error code to terminate the
2632 For inability to get SNI information, we return 0.
2633 We only return non-zero if re-setup failed.
2634 Only used for server-side TLS.
2638 exim_sni_handling_cb(gnutls_session_t session)
2640 char sni_name[MAX_HOST_LEN];
2641 size_t data_len = MAX_HOST_LEN;
2642 exim_gnutls_state_st *state = &state_server;
2643 unsigned int sni_type;
2645 uschar * dummy_errstr;
2647 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2648 if (rc != GNUTLS_E_SUCCESS)
2651 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2652 debug_printf("TLS: no SNI presented in handshake\n");
2654 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2655 gnutls_strerror(rc), rc);
2659 if (sni_type != GNUTLS_NAME_DNS)
2661 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2665 /* We now have a UTF-8 string in sni_name */
2666 old_pool = store_pool;
2667 store_pool = POOL_PERM;
2668 state->received_sni = string_copy_taint(US sni_name, TRUE);
2669 store_pool = old_pool;
2671 /* We set this one now so that variable expansions below will work */
2672 state->tlsp->sni = state->received_sni;
2674 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2675 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2677 if (!state->trigger_sni_changes)
2680 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2682 /* If the setup of certs/etc failed before handshake, TLS would not have
2683 been offered. The best we can do now is abort. */
2684 return GNUTLS_E_APPLICATION_ERROR_MIN;
2687 rc = tls_set_remaining_x509(state, &dummy_errstr);
2688 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2695 #ifndef DISABLE_EVENT
2697 We use this callback to get observability and detail-level control
2698 for an exim TLS connection (either direction), raising a tls:cert event
2699 for each cert in the chain presented by the peer. Any event
2700 can deny verification.
2702 Return 0 for the handshake to continue or non-zero to terminate.
2706 verify_cb(gnutls_session_t session)
2708 const gnutls_datum_t * cert_list;
2709 unsigned int cert_list_size = 0;
2710 gnutls_x509_crt_t crt;
2713 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2715 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2716 while (cert_list_size--)
2718 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2720 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2721 cert_list_size, gnutls_strerror(rc));
2725 state->tlsp->peercert = crt;
2726 if ((yield = event_raise(state->event_action,
2727 US"tls:cert", string_sprintf("%d", cert_list_size))))
2729 log_write(0, LOG_MAIN,
2730 "SSL verify denied by event-action: depth=%d: %s",
2731 cert_list_size, yield);
2732 return 1; /* reject */
2734 state->tlsp->peercert = NULL;
2744 ddump(gnutls_datum_t * d)
2746 gstring * g = string_get((d->size+1) * 2);
2747 uschar * s = d->data;
2748 for (unsigned i = d->size; i > 0; i--, s++)
2750 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2751 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2757 post_handshake_debug(exim_gnutls_state_st * state)
2759 #ifdef SUPPORT_GNUTLS_SESS_DESC
2760 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2763 #ifdef SUPPORT_GNUTLS_KEYLOG
2764 # ifdef EXIM_HAVE_TLS1_3
2765 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2770 gnutls_datum_t c, s;
2772 /* For TLS1.2 we only want the client random and the master secret */
2773 gnutls_session_get_random(state->session, &c, &s);
2774 gnutls_session_get_master_secret(state->session, &s);
2777 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2780 debug_printf("To get keying info for TLS1.3 is hard:\n"
2781 " Set environment variable SSLKEYLOGFILE to a filename relative to the spool directory,\n"
2782 " and make sure it is writable by the Exim runtime user.\n"
2783 " Add SSLKEYLOGFILE to keep_environment in the exim config.\n"
2784 " Start Exim as root.\n"
2785 " If using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
2786 " (works for TLS1.2 also, and saves cut-paste into file).\n"
2787 " Trying to use add_environment for this will not work\n");
2792 #ifdef EXIM_HAVE_TLS_RESUME
2794 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2795 unsigned incoming, const gnutls_datum_t * msg)
2797 DEBUG(D_tls) debug_printf("newticket cb\n");
2798 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2803 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2805 /* Should the server offer session resumption? */
2806 tls_in.resumption = RESUME_SUPPORTED;
2807 if (verify_check_host(&tls_resumption_hosts) == OK)
2810 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2811 an offered resumption is unacceptable. We lose one resumption per ticket
2812 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2813 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2814 least they go out in a single packet. */
2816 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2817 &server_sessticket_key)))
2818 tls_in.resumption |= RESUME_SERVER_TICKET;
2821 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2823 /* Try to tell if we see a ticket request */
2824 gnutls_handshake_set_hook_function(state->session,
2825 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2830 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2832 if (gnutls_session_resumption_requested(state->session))
2834 /* This tells us the client sent a full ticket. We use a
2835 callback on session-ticket request, elsewhere, to tell
2836 if a client asked for a ticket. */
2838 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2839 DEBUG(D_tls) debug_printf("client requested resumption\n");
2841 if (gnutls_session_is_resumed(state->session))
2843 tls_in.resumption |= RESUME_USED;
2844 DEBUG(D_tls) debug_printf("Session resumed\n");
2847 #endif /* EXIM_HAVE_TLS_RESUME */
2850 #ifdef EXIM_HAVE_ALPN
2851 /* Expand and convert an Exim list to a gnutls_datum list. False return for fail.
2852 NULL plist return for silent no-ALPN.
2856 tls_alpn_plist(const uschar * tls_alpn, const gnutls_datum_t ** plist, unsigned * plen,
2861 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
2866 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
2871 const uschar * list = exp_alpn;
2877 while (string_nextinlist(&list, &sep, NULL, 0)) cnt++;
2879 p = store_get(sizeof(gnutls_datum_t) * cnt, is_tainted(exp_alpn));
2881 for (int i = 0; s = string_nextinlist(&list, &sep, NULL, 0); i++)
2882 { p[i].data = s; p[i].size = Ustrlen(s); }
2883 *plist = (*plen = cnt) ? p : NULL;
2889 tls_server_set_acceptable_alpns(exim_gnutls_state_st * state, uschar ** errstr)
2892 const gnutls_datum_t * plist;
2895 if (tls_alpn_plist(tls_alpn, &plist, &plen, errstr) && plist)
2897 /* This seems to be only mandatory if the client sends an ALPN extension;
2898 not trying ALPN is ok. Need to decide how to support server-side must-alpn. */
2900 server_seen_alpn = 0;
2901 if (!(rc = gnutls_alpn_set_protocols(state->session, plist, plen,
2902 GNUTLS_ALPN_MANDATORY)))
2903 gnutls_handshake_set_hook_function(state->session,
2904 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2907 debug_printf("setting alpn protocols: %s\n", US gnutls_strerror(rc));
2910 #endif /* EXIM_HAVE_ALPN */
2912 /* ------------------------------------------------------------------------ */
2913 /* Exported functions */
2918 /*************************************************
2919 * Start a TLS session in a server *
2920 *************************************************/
2922 /* This is called when Exim is running as a server, after having received
2923 the STARTTLS command. It must respond to that command, and then negotiate
2927 errstr pointer to error string
2929 Returns: OK on success
2930 DEFER for errors before the start of the negotiation
2931 FAIL for errors during the negotiation; the server can't
2936 tls_server_start(uschar ** errstr)
2939 exim_gnutls_state_st * state = NULL;
2941 /* Check for previous activation */
2942 if (tls_in.active.sock >= 0)
2944 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2945 smtp_printf("554 Already in TLS\r\n", FALSE);
2949 /* Initialize the library. If it fails, it will already have logged the error
2950 and sent an SMTP response. */
2952 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2955 #ifdef MEASURE_TIMING
2957 gettimeofday(&t0, NULL);
2960 if ((rc = tls_init(NULL, NULL,
2961 tls_require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2963 #ifdef MEASURE_TIMING
2964 report_time_since(&t0, US"server tls_init (delta)");
2968 #ifdef EXIM_HAVE_ALPN
2969 tls_server_set_acceptable_alpns(state, errstr);
2972 #ifdef EXIM_HAVE_TLS_RESUME
2973 tls_server_resume_prehandshake(state);
2976 /* If this is a host for which certificate verification is mandatory or
2977 optional, set up appropriately. */
2979 if (verify_check_host(&tls_verify_hosts) == OK)
2982 debug_printf("TLS: a client certificate will be required\n");
2983 state->verify_requirement = VERIFY_REQUIRED;
2984 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2986 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2989 debug_printf("TLS: a client certificate will be requested but not required\n");
2990 state->verify_requirement = VERIFY_OPTIONAL;
2991 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2996 debug_printf("TLS: a client certificate will not be requested\n");
2997 state->verify_requirement = VERIFY_NONE;
2998 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
3001 #ifndef DISABLE_EVENT
3004 state->event_action = event_action;
3005 gnutls_session_set_ptr(state->session, state);
3006 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
3010 /* Register SNI handling; always, even if not in tls_certificate, so that the
3011 expansion variable $tls_sni is always available. */
3013 gnutls_handshake_set_post_client_hello_function(state->session,
3014 exim_sni_handling_cb);
3016 /* Set context and tell client to go ahead, except in the case of TLS startup
3017 on connection, where outputting anything now upsets the clients and tends to
3018 make them disconnect. We need to have an explicit fflush() here, to force out
3019 the response. Other smtp_printf() calls do not need it, because in non-TLS
3020 mode, the fflush() happens when smtp_getc() is called. */
3022 if (!state->tlsp->on_connect)
3024 smtp_printf("220 TLS go ahead\r\n", FALSE);
3028 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3029 that the GnuTLS library doesn't.
3030 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
3031 to set (and clear down afterwards) up a pull-timeout callback function that does
3032 a select, so we're no better off unless avoiding signals becomes an issue. */
3034 gnutls_transport_set_ptr2(state->session,
3035 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
3036 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
3037 state->fd_in = fileno(smtp_in);
3038 state->fd_out = fileno(smtp_out);
3040 sigalrm_seen = FALSE;
3041 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3043 rc = gnutls_handshake(state->session);
3044 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3047 if (rc != GNUTLS_E_SUCCESS)
3049 /* It seems that, except in the case of a timeout, we have to close the
3050 connection right here; otherwise if the other end is running OpenSSL it hangs
3051 until the server times out. */
3055 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
3056 gnutls_db_remove_session(state->session);
3060 tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
3061 (void) gnutls_alert_send_appropriate(state->session, rc);
3062 gnutls_deinit(state->session);
3063 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3064 state->lib_state = null_tls_preload;
3066 shutdown(state->fd_out, SHUT_WR);
3067 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
3068 (void)fclose(smtp_out);
3069 (void)fclose(smtp_in);
3070 smtp_out = smtp_in = NULL;
3076 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3077 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3078 tls_in.ext_master_secret = TRUE;
3081 #ifdef EXIM_HAVE_TLS_RESUME
3082 tls_server_resume_posthandshake(state);
3085 DEBUG(D_tls) post_handshake_debug(state);
3087 #ifdef EXIM_HAVE_ALPN
3088 if (server_seen_alpn > 0)
3091 { /* The client offered ALPN. See what was negotiated. */
3092 gnutls_datum_t p = {.size = 0};
3093 int rc = gnutls_alpn_get_selected_protocol(state->session, &p);
3095 debug_printf("ALPN negotiated: %.*s\n", (int)p.size, p.data);
3097 debug_printf("getting alpn protocol: %s\n", US gnutls_strerror(rc));
3101 else if (server_seen_alpn == 0)
3102 if (verify_check_host(&hosts_require_alpn) == OK)
3104 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
3105 tls_error(US"handshake", US"ALPN required but not negotiated", NULL, errstr);
3109 DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n");
3111 DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n");
3114 /* Verify after the fact */
3116 if (!verify_certificate(state, errstr))
3118 if (state->verify_requirement != VERIFY_OPTIONAL)
3120 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
3124 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
3128 /* Sets various Exim expansion variables; always safe within server */
3130 extract_exim_vars_from_tls_state(state);
3132 /* TLS has been set up. Adjust the input functions to read via TLS,
3133 and initialize appropriately. */
3135 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3137 receive_getc = tls_getc;
3138 receive_getbuf = tls_getbuf;
3139 receive_get_cache = tls_get_cache;
3140 receive_ungetc = tls_ungetc;
3141 receive_feof = tls_feof;
3142 receive_ferror = tls_ferror;
3143 receive_smtp_buffered = tls_smtp_buffered;
3152 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
3153 smtp_transport_options_block * ob)
3155 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3157 state->exp_tls_verify_cert_hostnames =
3159 string_domain_utf8_to_alabel(host->certname, NULL);
3164 debug_printf("TLS: server cert verification includes hostname: \"%s\"\n",
3165 state->exp_tls_verify_cert_hostnames);
3173 /* Given our list of RRs from the TLSA lookup, build a lookup block in
3174 GnuTLS-DANE's preferred format. Hang it on the state str for later
3175 use in DANE verification.
3177 We point at the dnsa data not copy it, so it must remain valid until
3178 after verification is done.*/
3181 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
3185 const char ** dane_data;
3186 int * dane_data_len;
3189 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3190 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3191 ) if (rr->type == T_TLSA) i++;
3193 dane_data = store_get(i * sizeof(uschar *), FALSE);
3194 dane_data_len = store_get(i * sizeof(int), FALSE);
3197 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3198 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3199 ) if (rr->type == T_TLSA && rr->size > 3)
3201 const uschar * p = rr->data;
3202 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
3203 uint8_t usage = p[0], sel = p[1], type = p[2];
3206 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
3208 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
3209 || (sel != 0 && sel != 1)
3214 case 0: /* Full: cannot check at present */
3216 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
3218 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
3223 tls_out.tlsa_usage |= 1<<usage;
3224 dane_data[i] = CS p;
3225 dane_data_len[i++] = rr->size;
3228 if (!i) return FALSE;
3230 dane_data[i] = NULL;
3231 dane_data_len[i] = 0;
3233 state->dane_data = (char * const *)dane_data;
3234 state->dane_data_len = dane_data_len;
3241 #ifdef EXIM_HAVE_TLS_RESUME
3242 /* On the client, get any stashed session for the given IP from hints db
3243 and apply it to the ssl-connection for attempted resumption. Although
3244 there is a gnutls_session_ticket_enable_client() interface it is
3245 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
3246 by deafult". There seems to be no way to disable them, so even hosts not
3247 enabled by the transport option will be sent a ticket request. We will
3248 however avoid storing and retrieving session information. */
3251 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
3252 host_item * host, smtp_transport_options_block * ob)
3254 tlsp->resumption = RESUME_SUPPORTED;
3255 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3257 dbdata_tls_session * dt;
3259 open_db dbblock, * dbm_file;
3262 debug_printf("check for resumable session for %s\n", host->address);
3263 tlsp->host_resumable = TRUE;
3264 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3265 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
3267 /* Key for the db is the IP. We'd like to filter the retrieved session
3268 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
3270 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
3271 if (!(rc = gnutls_session_set_data(session,
3272 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
3274 DEBUG(D_tls) debug_printf("good session\n");
3275 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3277 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
3278 US gnutls_strerror(rc));
3279 dbfn_close(dbm_file);
3286 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
3288 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
3289 but this flag is not set until the second. TLS 1.3 it's the other way about.
3290 Keep both calls as the session data cannot be extracted before handshake
3293 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
3298 DEBUG(D_tls) debug_printf("server offered session ticket\n");
3299 tlsp->ticket_received = TRUE;
3300 tlsp->resumption |= RESUME_SERVER_TICKET;
3302 if (tlsp->host_resumable)
3303 if (!(rc = gnutls_session_get_data2(session, &tkt)))
3305 open_db dbblock, * dbm_file;
3306 int dlen = sizeof(dbdata_tls_session) + tkt.size;
3307 dbdata_tls_session * dt = store_get(dlen, TRUE);
3309 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
3310 memcpy(dt->session, tkt.data, tkt.size);
3311 gnutls_free(tkt.data);
3313 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3315 /* key for the db is the IP */
3316 dbfn_delete(dbm_file, host->address);
3317 dbfn_write(dbm_file, host->address, dt, dlen);
3318 dbfn_close(dbm_file);
3321 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
3325 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
3330 /* With a TLS1.3 session, the ticket(s) are not seen until
3331 the first data read is attempted. And there's often two of them.
3332 Pick them up with this callback. We are also called for 1.2
3336 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
3337 unsigned incoming, const gnutls_datum_t * msg)
3339 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
3340 tls_support * tlsp = state->tlsp;
3342 DEBUG(D_tls) debug_printf("newticket cb\n");
3344 if (!tlsp->ticket_received)
3345 tls_save_session(tlsp, sess, state->host);
3351 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
3352 tls_support * tlsp, host_item * host,
3353 smtp_transport_options_block * ob)
3355 gnutls_session_set_ptr(state->session, state);
3356 gnutls_handshake_set_hook_function(state->session,
3357 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
3359 tls_retrieve_session(tlsp, state->session, host, ob);
3363 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
3364 tls_support * tlsp, host_item * host)
3366 if (gnutls_session_is_resumed(state->session))
3368 DEBUG(D_tls) debug_printf("Session resumed\n");
3369 tlsp->resumption |= RESUME_USED;
3372 tls_save_session(tlsp, state->session, host);
3374 #endif /* !DISABLE_TLS_RESUME */
3377 /*************************************************
3378 * Start a TLS session in a client *
3379 *************************************************/
3381 /* Called from the smtp transport after STARTTLS has been accepted.
3384 cctx connection context
3385 conn_args connection details
3386 cookie datum for randomness (not used)
3387 tlsp record details of channel configuration here; must be non-NULL
3388 errstr error string pointer
3390 Returns: TRUE for success with TLS session context set in smtp context,
3395 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3396 void * cookie ARG_UNUSED,
3397 tls_support * tlsp, uschar ** errstr)
3399 host_item * host = conn_args->host; /* for msgs and option-tests */
3400 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3401 smtp_transport_options_block * ob = tb
3402 ? (smtp_transport_options_block *)tb->options_block
3403 : &smtp_transport_option_defaults;
3405 exim_gnutls_state_st * state = NULL;
3406 uschar * cipher_list = NULL;
3408 #ifndef DISABLE_OCSP
3410 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3411 BOOL request_ocsp = require_ocsp ? TRUE
3412 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3415 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
3418 /* If dane is flagged, have either request or require dane for this host, and
3419 a TLSA record found. Therefore, dane verify required. Which implies cert must
3420 be requested and supplied, dane verify must pass, and cert verify irrelevant
3421 (incl. hostnames), and (caller handled) require_tls and sni=$domain */
3423 if (conn_args->dane && ob->dane_require_tls_ciphers)
3425 /* not using Expand_check_tlsvar because not yet in state */
3426 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3427 &cipher_list, errstr))
3429 cipher_list = cipher_list && *cipher_list
3430 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
3435 cipher_list = ob->tls_require_ciphers;
3438 #ifdef MEASURE_TIMING
3440 gettimeofday(&t0, NULL);
3443 if (tls_init(host, ob, cipher_list, &state, tlsp, errstr) != OK)
3446 #ifdef MEASURE_TIMING
3447 report_time_since(&t0, US"client tls_init (delta)");
3452 #ifdef EXIM_HAVE_ALPN
3454 const gnutls_datum_t * plist;
3457 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
3460 if (gnutls_alpn_set_protocols(state->session, plist, plen, 0) != 0)
3462 tls_error(US"alpn init", NULL, state->host, errstr);
3466 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
3469 log_write(0, LOG_MAIN, "ALPN unusable with this GnuTLS library version; ignoring \"%s\"\n",
3474 int dh_min_bits = ob->tls_dh_min_bits;
3475 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
3478 debug_printf("WARNING: tls_dh_min_bits far too low,"
3479 " clamping %d up to %d\n",
3480 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
3481 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
3484 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
3485 " acceptable bits to %d\n",
3487 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
3490 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
3491 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
3492 the specified host patterns if one of them is defined */
3495 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
3498 debug_printf("TLS: server certificate DANE required\n");
3499 state->verify_requirement = VERIFY_DANE;
3500 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3504 if ( ( state->exp_tls_verify_certificates
3505 && !ob->tls_verify_hosts
3506 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
3508 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3511 tls_client_setup_hostname_checks(host, state, ob);
3513 debug_printf("TLS: server certificate verification required\n");
3514 state->verify_requirement = VERIFY_REQUIRED;
3515 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3517 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3519 tls_client_setup_hostname_checks(host, state, ob);
3521 debug_printf("TLS: server certificate verification optional\n");
3522 state->verify_requirement = VERIFY_OPTIONAL;
3523 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
3528 debug_printf("TLS: server certificate verification not required\n");
3529 state->verify_requirement = VERIFY_NONE;
3530 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
3533 #ifndef DISABLE_OCSP
3534 /* supported since GnuTLS 3.1.3 */
3537 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
3538 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
3539 NULL, 0, NULL)) != OK)
3541 tls_error_gnu(state, US"cert-status-req", rc, errstr);
3544 tlsp->ocsp = OCSP_NOT_RESP;
3548 #ifdef EXIM_HAVE_TLS_RESUME
3549 tls_client_resume_prehandshake(state, tlsp, host, ob);
3552 #ifndef DISABLE_EVENT
3553 if (tb && tb->event_action)
3555 state->event_action = tb->event_action;
3556 gnutls_session_set_ptr(state->session, state);
3557 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
3561 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
3562 state->fd_in = cctx->sock;
3563 state->fd_out = cctx->sock;
3565 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
3566 /* There doesn't seem to be a built-in timeout on connection. */
3568 sigalrm_seen = FALSE;
3569 ALARM(ob->command_timeout);
3571 rc = gnutls_handshake(state->session);
3572 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3575 if (rc != GNUTLS_E_SUCCESS)
3579 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
3580 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
3583 tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
3587 DEBUG(D_tls) post_handshake_debug(state);
3591 if (!verify_certificate(state, errstr))
3593 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
3597 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3598 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3599 tlsp->ext_master_secret = TRUE;
3602 #ifndef DISABLE_OCSP
3607 gnutls_datum_t stapling;
3608 gnutls_ocsp_resp_t resp;
3609 gnutls_datum_t printed;
3613 # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
3614 (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
3616 (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
3619 if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0
3620 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
3621 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
3624 debug_printf("%.4096s", printed.data);
3625 gnutls_free(printed.data);
3628 (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
3630 (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
3633 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
3635 tlsp->ocsp = OCSP_FAILED;
3636 tls_error(US"certificate status check failed", NULL, state->host, errstr);
3642 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
3643 tlsp->ocsp = OCSP_VFIED;
3648 #ifdef EXIM_HAVE_TLS_RESUME
3649 tls_client_resume_posthandshake(state, tlsp, host);
3652 #ifdef EXIM_HAVE_ALPN
3653 if (ob->tls_alpn) /* We requested. See what was negotiated. */
3655 gnutls_datum_t p = {.size = 0};
3657 if (gnutls_alpn_get_selected_protocol(state->session, &p) == 0)
3658 { DEBUG(D_tls) debug_printf("ALPN negotiated: '%.*s'\n", (int)p.size, p.data); }
3659 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
3661 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
3662 tls_error(US"handshake", US"ALPN required but not negotiated", state->host, errstr);
3666 DEBUG(D_tls) debug_printf("No ALPN negotiated");
3670 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
3672 extract_exim_vars_from_tls_state(state);
3674 cctx->tls_ctx = state;
3683 ct_ctx client TLS context pointer, or NULL for the one global server context
3687 tls_shutdown_wr(void * ct_ctx)
3689 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3690 tls_support * tlsp = state->tlsp;
3692 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3694 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
3696 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
3697 gnutls_bye(state->session, GNUTLS_SHUT_WR);
3700 /*************************************************
3701 * Close down a TLS session *
3702 *************************************************/
3704 /* This is also called from within a delivery subprocess forked from the
3705 daemon, to shut down the TLS library, without actually doing a shutdown (which
3706 would tamper with the TLS session in the parent process).
3709 ct_ctx client context pointer, or NULL for the one global server context
3710 do_shutdown 0 no data-flush or TLS close-alert
3711 1 if TLS close-alert is to be sent,
3712 2 if also response to be waited for (2s timeout)
3718 tls_close(void * ct_ctx, int do_shutdown)
3720 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3721 tls_support * tlsp = state->tlsp;
3723 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3727 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3728 do_shutdown > 1 ? " (with response-wait)" : "");
3730 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
3733 gnutls_bye(state->session, do_shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
3737 if (!ct_ctx) /* server */
3739 receive_getc = smtp_getc;
3740 receive_getbuf = smtp_getbuf;
3741 receive_get_cache = smtp_get_cache;
3742 receive_ungetc = smtp_ungetc;
3743 receive_feof = smtp_feof;
3744 receive_ferror = smtp_ferror;
3745 receive_smtp_buffered = smtp_buffered;
3748 gnutls_deinit(state->session);
3749 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3750 state->lib_state = null_tls_preload;
3752 tlsp->active.sock = -1;
3753 tlsp->active.tls_ctx = NULL;
3754 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3755 tlsp->channelbinding = NULL;
3758 if (state->xfer_buffer) store_free(state->xfer_buffer);
3765 tls_refill(unsigned lim)
3767 exim_gnutls_state_st * state = &state_server;
3770 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, buffersize=%u)\n",
3771 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
3773 sigalrm_seen = FALSE;
3774 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3778 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
3779 MIN(ssl_xfer_buffer_size, lim));
3780 while (inbytes == GNUTLS_E_AGAIN);
3782 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3784 if (had_command_timeout) /* set by signal handler */
3785 smtp_command_timeout_exit(); /* does not return */
3786 if (had_command_sigterm)
3787 smtp_command_sigterm_exit();
3788 if (had_data_timeout)
3789 smtp_data_timeout_exit();
3790 if (had_data_sigint)
3791 smtp_data_sigint_exit();
3793 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3794 TLS session has been closed down, not that the socket itself has been closed
3795 down. Revert to non-TLS handling. */
3799 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3800 state->xfer_error = TRUE;
3804 else if (inbytes == 0)
3806 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3807 tls_close(NULL, TLS_NO_SHUTDOWN);
3811 /* Handle genuine errors */
3813 else if (inbytes < 0)
3815 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3816 record_io_error(state, (int) inbytes, US"recv", NULL);
3817 state->xfer_error = TRUE;
3820 #ifndef DISABLE_DKIM
3821 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3823 state->xfer_buffer_hwm = (int) inbytes;
3824 state->xfer_buffer_lwm = 0;
3828 /*************************************************
3829 * TLS version of getc *
3830 *************************************************/
3832 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3833 it refills the buffer via the GnuTLS reading function.
3834 Only used by the server-side TLS.
3836 This feeds DKIM and should be used for all message-body reads.
3838 Arguments: lim Maximum amount to read/buffer
3839 Returns: the next character or EOF
3843 tls_getc(unsigned lim)
3845 exim_gnutls_state_st * state = &state_server;
3847 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3848 if (!tls_refill(lim))
3849 return state->xfer_error ? EOF : smtp_getc(lim);
3851 /* Something in the buffer; return next uschar */
3853 return state->xfer_buffer[state->xfer_buffer_lwm++];
3857 tls_getbuf(unsigned * len)
3859 exim_gnutls_state_st * state = &state_server;
3863 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3864 if (!tls_refill(*len))
3866 if (!state->xfer_error) return smtp_getbuf(len);
3871 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3873 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3874 state->xfer_buffer_lwm += size;
3883 #ifndef DISABLE_DKIM
3884 exim_gnutls_state_st * state = &state_server;
3885 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3887 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3893 tls_could_read(void)
3895 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3896 || gnutls_record_check_pending(state_server.session) > 0;
3900 /*************************************************
3901 * Read bytes from TLS channel *
3902 *************************************************/
3904 /* This does not feed DKIM, so if the caller uses this for reading message body,
3905 then the caller must feed DKIM.
3908 ct_ctx client context pointer, or NULL for the one global server context
3912 Returns: the number of bytes read
3913 -1 after a failed read, including EOF
3917 tls_read(void * ct_ctx, uschar *buff, size_t len)
3919 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3925 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3927 debug_printf("*** PROBABLY A BUG *** " \
3928 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3929 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3932 debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, len=" SIZE_T_FMT ")\n",
3933 state->session, buff, len);
3937 inbytes = gnutls_record_recv(state->session, buff, len);
3938 while (inbytes == GNUTLS_E_AGAIN);
3940 if (inbytes > 0) return inbytes;
3943 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3947 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3948 record_io_error(state, (int)inbytes, US"recv", NULL);
3957 /*************************************************
3958 * Write bytes down TLS channel *
3959 *************************************************/
3963 ct_ctx client context pointer, or NULL for the one global server context
3966 more more data expected soon
3968 Calling with len zero and more unset will flush buffered writes. The buff
3969 argument can be null for that case.
3971 Returns: the number of bytes after a successful write,
3972 -1 after a failed write
3976 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3980 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3983 if (more && !state->corked)
3985 DEBUG(D_tls) debug_printf("gnutls_record_cork(session=%p)\n", state->session);
3986 gnutls_record_cork(state->session);
3987 state->corked = TRUE;
3991 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3992 buff, left, more ? ", more" : "");
3996 DEBUG(D_tls) debug_printf("gnutls_record_send(session=%p, buffer=%p, left=" SIZE_T_FMT ")\n",
3997 state->session, buff, left);
4001 outbytes = gnutls_record_send(state->session, buff, left);
4002 while (outbytes == GNUTLS_E_AGAIN);
4004 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
4008 #ifdef GNUTLS_E_PREMATURE_TERMINATION
4009 if ( outbytes == GNUTLS_E_PREMATURE_TERMINATION && errno == ECONNRESET
4010 && !ct_ctx && f.smtp_in_quit
4012 { /* Outlook, dammit */
4013 if (LOGGING(protocol_detail))
4014 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4015 " SMTP response and TLS close\n", sender_host_address);
4017 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4018 " client reset TCP before TLS close\n", sender_host_address);
4023 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
4024 record_io_error(state, outbytes, US"send", NULL);
4030 record_io_error(state, 0, US"send", US"TLS channel closed on write");
4041 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
4047 if (!more && state->corked)
4049 DEBUG(D_tls) debug_printf("gnutls_record_uncork(session=%p)\n", state->session);
4051 /* We can't use GNUTLS_RECORD_WAIT here, as it retries on
4052 GNUTLS_E_AGAIN || GNUTLS_E_INTR, which would break our timeout set by alarm().
4053 The GNUTLS_E_AGAIN should not happen ever, as our sockets are blocking anyway.
4054 But who knows. (That all relies on the fact that GNUTLS_E_INTR and GNUTLS_E_AGAIN
4055 match the EINTR and EAGAIN errno values.) */
4056 outbytes = gnutls_record_uncork(state->session, 0);
4057 while (outbytes == GNUTLS_E_AGAIN);
4061 record_io_error(state, len, US"uncork", NULL);
4065 state->corked = FALSE;
4075 /*************************************************
4076 * Random number generation *
4077 *************************************************/
4079 /* Pseudo-random number generation. The result is not expected to be
4080 cryptographically strong but not so weak that someone will shoot themselves
4081 in the foot using it as a nonce in input in some email header scheme or
4082 whatever weirdness they'll twist this into. The result should handle fork()
4083 and avoid repeating sequences. OpenSSL handles that for us.
4087 Returns a random number in range [0, max-1]
4090 #ifdef HAVE_GNUTLS_RND
4092 vaguely_random_number(int max)
4096 uschar smallbuf[sizeof(r)];
4101 needed_len = sizeof(r);
4102 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4103 asked for a number less than 10. */
4105 for (r = max, i = 0; r; ++i)
4111 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
4114 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback\n");
4115 return vaguely_random_number_fallback(max);
4118 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4121 /* We don't particularly care about weighted results; if someone wants
4122 * smooth distribution and cares enough then they should submit a patch then. */
4125 #else /* HAVE_GNUTLS_RND */
4127 vaguely_random_number(int max)
4129 return vaguely_random_number_fallback(max);
4131 #endif /* HAVE_GNUTLS_RND */
4136 /*************************************************
4137 * Let tls_require_ciphers be checked at startup *
4138 *************************************************/
4140 /* The tls_require_ciphers option, if set, must be something which the
4143 Returns: NULL on success, or error message
4147 tls_validate_require_cipher(void)
4150 uschar *expciphers = NULL;
4151 gnutls_priority_t priority_cache;
4153 uschar * dummy_errstr;
4155 #ifdef GNUTLS_AUTO_GLOBAL_INIT
4156 # define validate_check_rc(Label) do { \
4157 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \
4158 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
4159 # define return_deinit(Label) do { return (Label); } while (0)
4161 # define validate_check_rc(Label) do { \
4162 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
4163 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
4164 # define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
4167 if (exim_gnutls_base_init_done)
4168 log_write(0, LOG_MAIN|LOG_PANIC,
4169 "already initialised GnuTLS, Exim developer bug");
4171 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
4172 if (!gnutls_allow_auto_pkcs11)
4174 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
4175 validate_check_rc(US"gnutls_pkcs11_init");
4178 #ifndef GNUTLS_AUTO_GLOBAL_INIT
4179 rc = gnutls_global_init();
4180 validate_check_rc(US"gnutls_global_init()");
4182 exim_gnutls_base_init_done = TRUE;
4184 if (!(tls_require_ciphers && *tls_require_ciphers))
4185 return_deinit(NULL);
4187 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4189 return_deinit(US"failed to expand tls_require_ciphers");
4191 if (!(expciphers && *expciphers))
4192 return_deinit(NULL);
4195 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4197 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
4198 validate_check_rc(string_sprintf(
4199 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
4200 expciphers, errpos - CS expciphers, errpos));
4202 #undef return_deinit
4203 #undef validate_check_rc
4204 #ifndef GNUTLS_AUTO_GLOBAL_INIT
4205 gnutls_global_deinit();
4214 /*************************************************
4215 * Report the library versions. *
4216 *************************************************/
4218 /* See a description in tls-openssl.c for an explanation of why this exists.
4220 Arguments: a FILE* to print the results to
4225 tls_version_report(FILE *f)
4227 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
4230 gnutls_check_version(NULL));
4233 #endif /*!MACRO_PREDEF*/
4236 /* End of tls-gnu.c */