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");
164 gnutls_global_set_audit_log_function()
167 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
170 /* Local static variables for GnuTLS */
172 /* Values for verify_requirement */
174 enum peer_verify_requirement
175 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
177 /* This holds most state for server or client; with this, we can set up an
178 outbound TLS-enabled connection in an ACL callout, while not stomping all
179 over the TLS variables available for expansion.
181 Some of these correspond to variables in globals.c; those variables will
182 be set to point to content in one of these instances, as appropriate for
183 the stage of the process lifetime.
185 Not handled here: global tlsp->tls_channelbinding.
188 typedef struct exim_gnutls_state {
189 gnutls_session_t session;
191 exim_tlslib_state lib_state;
192 #define x509_cred libdata0
193 #define pri_cache libdata1
195 enum peer_verify_requirement verify_requirement;
199 BOOL peer_cert_verified:1;
200 BOOL peer_dane_verified:1;
201 BOOL trigger_sni_changes:1;
202 BOOL have_set_peerdn:1;
203 BOOL xfer_eof:1; /*XXX never gets set! */
209 const struct host_item *host; /* NULL if server */
210 gnutls_x509_crt_t peercert;
213 uschar *received_sni;
215 const uschar *tls_certificate;
216 const uschar *tls_privatekey;
217 const uschar *tls_sni; /* client send only, not received */
218 const uschar *tls_verify_certificates;
219 const uschar *tls_crl;
220 const uschar *tls_require_ciphers;
222 uschar *exp_tls_certificate;
223 uschar *exp_tls_privatekey;
224 uschar *exp_tls_verify_certificates;
226 uschar *exp_tls_require_ciphers;
227 const uschar *exp_tls_verify_cert_hostnames;
228 #ifndef DISABLE_EVENT
229 uschar *event_action;
232 char * const * dane_data;
233 const int * dane_data_len;
236 tls_support *tlsp; /* set in tls_init() */
241 } exim_gnutls_state_st;
243 static const exim_gnutls_state_st exim_gnutls_state_init = {
244 /* all elements not explicitly intialised here get 0/NULL/FALSE */
249 /* Not only do we have our own APIs which don't pass around state, assuming
250 it's held in globals, GnuTLS doesn't appear to let us register callback data
251 for callbacks, or as part of the session, so we have to keep a "this is the
252 context we're currently dealing with" pointer and rely upon being
253 single-threaded to keep from processing data on an inbound TLS connection while
254 talking to another TLS connection for an outbound check. This does mean that
255 there's no way for heart-beats to be responded to, for the duration of the
257 XXX But see gnutls_session_get_ptr()
260 static exim_gnutls_state_st state_server = {
261 /* all elements not explicitly intialised here get 0/NULL/FALSE */
266 #ifndef GNUTLS_AUTO_DHPARAMS
267 /* dh_params are initialised once within the lifetime of a process using TLS;
268 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
269 don't want to repeat this. */
271 static gnutls_dh_params_t dh_server_params = NULL;
274 static int ssl_session_timeout = 7200; /* Two hours */
276 static const uschar * const exim_default_gnutls_priority = US"NORMAL";
278 /* Guard library core initialisation */
280 static BOOL exim_gnutls_base_init_done = FALSE;
283 static BOOL gnutls_buggy_ocsp = FALSE;
284 static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
287 #ifdef EXIM_HAVE_ALPN
288 static int server_seen_alpn = -1; /* count of names */
290 #ifdef EXIM_HAVE_TLS_RESUME
291 static gnutls_datum_t server_sessticket_key;
295 /* ------------------------------------------------------------------------ */
298 #define MAX_HOST_LEN 255
300 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
301 the library logging; a value less than 0 disables the calls to set up logging
302 callbacks. GNuTLS also looks for an environment variable - except not for
303 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
304 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
305 but the env var must be added to /etc/sudoers too. */
306 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
307 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
310 #ifndef EXIM_CLIENT_DH_MIN_BITS
311 # define EXIM_CLIENT_DH_MIN_BITS 1024
314 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
315 can ask for a bit-strength. Without that, we stick to the constant we had
317 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
318 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
321 #define Expand_check_tlsvar(Varname, errstr) \
322 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
324 #if GNUTLS_VERSION_NUMBER >= 0x020c00
325 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
326 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
327 # define HAVE_GNUTLS_RND
328 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
329 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
330 * isn't available sometimes, so this needs to become a conditional
331 * compilation; the sanest way to deal with this being a problem on
332 * older OSes is to block it in the Local/Makefile with this compiler
334 # ifndef AVOID_GNUTLS_PKCS11
335 # define HAVE_GNUTLS_PKCS11
336 # endif /* AVOID_GNUTLS_PKCS11 */
342 /* ------------------------------------------------------------------------ */
343 /* Callback declarations */
345 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
346 static void exim_gnutls_logger_cb(int level, const char *message);
349 static int exim_sni_handling_cb(gnutls_session_t session);
351 #ifdef EXIM_HAVE_TLS_RESUME
353 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
354 unsigned incoming, const gnutls_datum_t * msg);
358 /*************************************************
360 *************************************************/
362 /* Called from lots of places when errors occur before actually starting to do
363 the TLS handshake, that is, while the session is still in clear. Always returns
364 DEFER for a server and FAIL for a client so that most calls can use "return
365 tls_error(...)" to do this processing and then give an appropriate return. A
366 single function is used for both server and client, because it is called from
367 some shared functions.
370 prefix text to include in the logged error
371 msg additional error string (may be NULL)
372 usually obtained from gnutls_strerror()
373 host NULL if setting up a server;
374 the connected host if setting up a client
375 errstr pointer to returned error string
377 Returns: OK/DEFER/FAIL
381 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
385 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
386 return host ? FAIL : DEFER;
391 tls_error_gnu(exim_gnutls_state_st * state, const uschar *prefix, int err,
394 return tls_error(prefix,
395 state && err == GNUTLS_E_FATAL_ALERT_RECEIVED
396 ? US gnutls_alert_get_name(gnutls_alert_get(state->session))
397 : US gnutls_strerror(err),
398 state ? state->host : NULL,
403 tls_error_sys(const uschar *prefix, int err, const host_item *host,
406 return tls_error(prefix, US strerror(err), host, errstr);
410 /* ------------------------------------------------------------------------ */
416 tls_is_buggy_ocsp(void)
419 uschar maj, mid, mic;
421 s = CUS gnutls_check_version(NULL);
425 while (*s && *s != '.') s++;
433 while (*s && *s != '.') s++;
435 return mic <= (mid == 3 ? 16 : 3);
445 tls_g_init(uschar ** errstr)
448 DEBUG(D_tls) debug_printf("GnuTLS global init required\n");
450 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
451 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
452 which loads modules from a config file, which sounds good and may be wanted
453 by some sysadmin, but also means in common configurations that GNOME keyring
454 environment variables are used and so breaks for users calling mailq.
455 To prevent this, we init PKCS11 first, which is the documented approach. */
457 if (!gnutls_allow_auto_pkcs11)
458 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
459 return tls_error_gnu(NULL, US"gnutls_pkcs11_init", rc, errstr);
462 #ifndef GNUTLS_AUTO_GLOBAL_INIT
463 if ((rc = gnutls_global_init()))
464 return tls_error_gnu(NULL, US"gnutls_global_init", rc, errstr);
467 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
470 gnutls_global_set_log_function(exim_gnutls_logger_cb);
471 /* arbitrarily chosen level; bump up to 9 for more */
472 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
477 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
478 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
481 exim_gnutls_base_init_done = TRUE;
487 /* Daemon-call before each connection. Nothing to do for GnuTLS. */
490 tls_per_lib_daemon_tick(void)
494 /* Daemon one-time initialisation */
497 tls_per_lib_daemon_init(void)
499 uschar * dummy_errstr;
500 static BOOL once = FALSE;
502 if (!exim_gnutls_base_init_done)
503 tls_g_init(&dummy_errstr);
509 #ifdef EXIM_HAVE_TLS_RESUME
510 /* We are dependent on the GnuTLS implementation of the Session Ticket
511 encryption; both the strength and the key rotation period. We hope that
512 the strength at least matches that of the ciphersuite (but GnuTLS does not
515 gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
516 if (f.running_in_test_harness) ssl_session_timeout = 6;
519 tls_daemon_creds_reload();
523 /* ------------------------------------------------------------------------ */
525 /*************************************************
526 * Deal with logging errors during I/O *
527 *************************************************/
529 /* We have to get the identity of the peer from saved data.
532 state the current GnuTLS exim state container
533 rc the GnuTLS error code, or 0 if it's a local error
534 when text identifying read or write
535 text local error text when rc is 0
541 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
546 msg = rc == GNUTLS_E_FATAL_ALERT_RECEIVED
547 ? string_sprintf("A TLS fatal alert has been received: %s",
548 US gnutls_alert_get_name(gnutls_alert_get(state->session)))
549 #ifdef GNUTLS_E_PREMATURE_TERMINATION
550 : rc == GNUTLS_E_PREMATURE_TERMINATION && errno
551 ? string_sprintf("%s: syscall: %s", US gnutls_strerror(rc), strerror(errno))
553 : US gnutls_strerror(rc);
555 (void) tls_error(when, msg, state->host, &errstr);
558 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
559 state->host->name, state->host->address, errstr);
562 uschar * conn_info = smtp_get_connection_info();
563 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
564 /* I'd like to get separated H= here, but too hard for now */
565 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
572 /*************************************************
573 * Set various Exim expansion vars *
574 *************************************************/
576 #define exim_gnutls_cert_err(Label) \
579 if (rc != GNUTLS_E_SUCCESS) \
581 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
582 (Label), gnutls_strerror(rc)); \
588 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
592 rc = gnutls_x509_crt_init(crtp);
593 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
595 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
596 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
601 #undef exim_gnutls_cert_err
604 /* We set various Exim global variables from the state, once a session has
605 been established. With TLS callouts, may need to change this to stack
606 variables, or just re-call it with the server state after client callout
609 Make sure anything set here is unset in tls_getc().
613 tls_bits strength indicator
614 tls_certificate_verified bool indicator
615 tls_channelbinding for some SASL mechanisms
618 tls_peercert pointer to library internal
620 tls_sni a (UTF-8) string
621 tls_ourcert pointer to library internal
624 state the relevant exim_gnutls_state_st *
628 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
630 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
633 gnutls_datum_t channel;
635 tls_support * tlsp = state->tlsp;
637 tlsp->active.sock = state->fd_out;
638 tlsp->active.tls_ctx = state;
640 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
642 tlsp->certificate_verified = state->peer_cert_verified;
644 tlsp->dane_verified = state->peer_dane_verified;
647 /* note that tls_channelbinding is not saved to the spool file, since it's
648 only available for use for authenticators while this TLS session is running. */
650 tlsp->channelbinding = NULL;
651 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
654 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
655 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
658 /* Declare the taintedness of the binding info. On server, untainted; on
659 client, tainted - being the Finish msg from the server. */
661 old_pool = store_pool;
662 store_pool = POOL_PERM;
663 tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
665 store_pool = old_pool;
666 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
670 /* peercert is set in peer_status() */
671 tlsp->peerdn = state->peerdn;
673 /* do not corrupt sni sent by client; record sni rxd by server */
675 tlsp->sni = state->received_sni;
677 /* record our certificate */
679 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
680 gnutls_x509_crt_t crt;
682 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
689 #ifndef GNUTLS_AUTO_DHPARAMS
690 /*************************************************
691 * Setup up DH parameters *
692 *************************************************/
694 /* Generating the D-H parameters may take a long time. They only need to
695 be re-generated every so often, depending on security policy. What we do is to
696 keep these parameters in a file in the spool directory. If the file does not
697 exist, we generate them. This means that it is easy to cause a regeneration.
699 The new file is written as a temporary file and renamed, so that an incomplete
700 file is never present. If two processes both compute some new parameters, you
701 waste a bit of effort, but it doesn't seem worth messing around with locking to
704 Returns: OK/DEFER/FAIL
708 init_server_dh(uschar ** errstr)
711 unsigned int dh_bits;
712 gnutls_datum_t m = {.data = NULL, .size = 0};
713 uschar filename_buf[PATH_MAX];
714 uschar *filename = NULL;
716 uschar *exp_tls_dhparam;
717 BOOL use_file_in_spool = FALSE;
718 host_item *host = NULL; /* dummy for macros */
720 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
722 if ((rc = gnutls_dh_params_init(&dh_server_params)))
723 return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
725 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
728 if (!exp_tls_dhparam)
730 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
731 m.data = US std_dh_prime_default();
732 m.size = Ustrlen(m.data);
734 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
735 use_file_in_spool = TRUE;
736 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
738 DEBUG(D_tls) debug_printf("Requested no DH parameters\n");
741 else if (exp_tls_dhparam[0] != '/')
743 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
744 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
745 m.size = Ustrlen(m.data);
748 filename = exp_tls_dhparam;
752 if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
753 return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
754 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
758 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
759 /* If you change this constant, also change dh_param_fn_ext so that we can use a
760 different filename and ensure we have sufficient bits. */
762 if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
763 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
765 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits\n",
768 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
770 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits\n",
774 /* Some clients have hard-coded limits. */
775 if (dh_bits > tls_dh_max_bits)
778 debug_printf("tls_dh_max_bits clamping override, using %d bits instead\n",
780 dh_bits = tls_dh_max_bits;
783 if (use_file_in_spool)
785 if (!string_format(filename_buf, sizeof(filename_buf),
786 "%s/gnutls-params-%d", spool_directory, dh_bits))
787 return tls_error(US"overlong filename", NULL, NULL, errstr);
788 filename = filename_buf;
791 /* Open the cache file for reading and if successful, read it and set up the
794 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
800 if (fstat(fd, &statbuf) < 0) /* EIO */
804 return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
806 if (!S_ISREG(statbuf.st_mode))
809 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
811 if (!(fp = fdopen(fd, "rb")))
815 return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
816 saved_errno, NULL, errstr);
819 m.size = statbuf.st_size;
820 if (!(m.data = store_malloc(m.size)))
823 return tls_error_sys(US"malloc failed", errno, NULL, errstr);
825 if (!(sz = fread(m.data, m.size, 1, fp)))
830 return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
834 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
837 return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
838 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
841 /* If the file does not exist, fall through to compute new data and cache it.
842 If there was any other opening error, it is serious. */
844 else if (errno == ENOENT)
848 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
851 return tls_error(string_open_failed("\"%s\" for reading", filename),
854 /* If ret < 0, either the cache file does not exist, or the data it contains
855 is not useful. One particular case of this is when upgrading from an older
856 release of Exim in which the data was stored in a different format. We don't
857 try to be clever and support both formats; we just regenerate new data in this
863 unsigned int dh_bits_gen = dh_bits;
865 if ((PATH_MAX - Ustrlen(filename)) < 10)
866 return tls_error(US"Filename too long to generate replacement",
867 filename, NULL, errstr);
869 temp_fn = string_copy(US"exim-dh.XXXXXXX");
870 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
871 return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
872 (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
874 /* GnuTLS overshoots! If we ask for 2236, we might get 2237 or more. But
875 there's no way to ask GnuTLS how many bits there really are. We can ask
876 how many bits were used in a TLS session, but that's it! The prime itself
877 is hidden behind too much abstraction. So we ask for less, and proceed on
878 a wing and a prayer. First attempt, subtracted 3 for 2233 and got 2240. */
880 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
882 dh_bits_gen = dh_bits - 10;
884 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
889 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
891 if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
892 return tls_error_gnu(NULL, US"gnutls_dh_params_generate2", rc, errstr);
894 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
895 and I confirmed that a NULL call to get the size first is how the GnuTLS
896 sample apps handle this. */
900 if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
901 GNUTLS_X509_FMT_PEM, m.data, &sz))
902 && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
903 return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3(NULL) sizing",
906 if (!(m.data = store_malloc(m.size)))
907 return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
909 /* this will return a size 1 less than the allocation size above */
910 if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
914 return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3() real", rc, errstr);
916 m.size = sz; /* shrink by 1, probably */
918 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
921 return tls_error_sys(US"TLS cache write D-H params failed",
922 errno, NULL, errstr);
925 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
926 return tls_error_sys(US"TLS cache write D-H params final newline failed",
927 errno, NULL, errstr);
929 if ((rc = close(fd)))
930 return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
932 if (Urename(temp_fn, filename) < 0)
933 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
934 temp_fn, filename), errno, NULL, errstr);
936 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
939 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
947 /* Create and install a selfsigned certificate, for use in server mode. */
950 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
952 gnutls_x509_crt_t cert = NULL;
954 gnutls_x509_privkey_t pkey = NULL;
955 const uschar * where;
958 #ifndef SUPPORT_SELFSIGN
959 where = US"library too old";
960 rc = GNUTLS_E_NO_CERTIFICATE_FOUND;
964 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
965 where = US"initialising pkey";
966 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
968 where = US"initialising cert";
969 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
971 where = US"generating pkey"; /* Hangs on 2.12.23 */
972 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
973 #ifdef SUPPORT_PARAM_TO_PK_BITS
974 # ifndef GNUTLS_SEC_PARAM_MEDIUM
975 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
977 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
984 where = US"configuring cert";
986 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
987 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
988 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
989 || (rc = gnutls_x509_crt_set_expiration_time(cert, (long)2 * 60 * 60)) /* 2 hour */
990 || (rc = gnutls_x509_crt_set_key(cert, pkey))
992 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
993 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
994 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
995 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
996 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
997 GNUTLS_OID_X520_COMMON_NAME, 0,
998 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
1002 where = US"signing cert";
1003 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
1005 where = US"installing selfsign cert";
1007 if ((rc = gnutls_certificate_set_x509_key(state->lib_state.x509_cred,
1014 if (cert) gnutls_x509_crt_deinit(cert);
1015 if (pkey) gnutls_x509_privkey_deinit(pkey);
1019 rc = tls_error_gnu(state, where, rc, errstr);
1026 /* Add certificate and key, from files.
1029 Zero or negative: good. Negate value for certificate index if < 0.
1030 Greater than zero: FAIL or DEFER code.
1034 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
1035 const uschar * certfile, const uschar * keyfile, uschar ** errstr)
1037 int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
1038 CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
1040 return tls_error_gnu(state,
1041 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
1047 #if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1048 /* Load an OCSP proof from file for sending by the server. Called
1049 on getting a status-request handshake message, for earlier versions
1053 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
1054 gnutls_datum_t * ocsp_response)
1057 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
1059 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
1061 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
1063 tls_in.ocsp = OCSP_NOT_RESP;
1064 return GNUTLS_E_NO_CERTIFICATE_STATUS;
1067 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1073 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1074 /* Make a note that we saw a status-request */
1076 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
1077 const uschar * data, unsigned size)
1079 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1082 case 5: /* Status Request */
1083 DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
1084 tls_in.ocsp = OCSP_NOT_RESP;
1086 #ifdef EXIM_HAVE_ALPN
1087 case 16: /* Application Layer Protocol Notification */
1088 /* The format of "data" here doesn't seem to be documented, but appears
1089 to be a 2-byte field with a (redundant, given the "size" arg) total length
1090 then a sequence of one-byte size then string (not nul-term) names. The
1091 latter is as described in OpenSSL documentation. */
1093 DEBUG(D_tls) debug_printf("Seen ALPN extension from client (s=%u):", size);
1094 for (const uschar * s = data+2; s-data < size-1; s += *s + 1)
1097 DEBUG(D_tls) debug_printf(" '%.*s'", (int)*s, s+1);
1099 DEBUG(D_tls) debug_printf("\n");
1100 if (server_seen_alpn > 1)
1102 DEBUG(D_tls) debug_printf("TLS: too many ALPNs presented in handshake\n");
1103 return GNUTLS_E_NO_APPLICATION_PROTOCOL;
1111 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
1113 tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
1114 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1116 /* Call fn for each extension seen. 3.6.3 onwards */
1117 return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
1118 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
1122 # ifdef notdef_crashes
1123 /* Make a note that we saw a status-response */
1125 tls_server_servercerts_ext(void * ctx, unsigned tls_id,
1126 const unsigned char *data, unsigned size)
1128 /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
1129 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1130 if (FALSE && tls_id == 5) /* status_request */
1132 DEBUG(D_tls) debug_printf("Seen status_request extension\n");
1133 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1134 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1140 /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
1142 tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
1143 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1145 /* Call fn for each extension seen. 3.6.3 onwards */
1146 # ifdef notdef_crashes
1148 return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
1151 #endif /*SUPPORT_GNUTLS_EXT_RAW_PARSE*/
1153 /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
1154 "Handshake Protocol: Certificate" record.
1155 So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
1157 This is different to tls1.2 - where it is a separate record (wireshark term) / handshake message (gnutls term).
1160 #if defined(EXIM_HAVE_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1161 /* Callback for certificate-status, on server. We sent stapled OCSP. */
1163 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
1164 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1166 DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
1167 # ifdef SUPPORT_SRV_OCSP_STACK
1168 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1169 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1171 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1176 /* Callback for handshake messages, on server */
1178 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
1179 unsigned incoming, const gnutls_datum_t * msg)
1181 /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
1184 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1185 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
1186 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
1187 case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
1188 return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
1190 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
1191 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
1192 # ifdef EXIM_HAVE_TLS_RESUME
1193 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
1194 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
1203 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1205 tls_server_testharness_ocsp_fiddle(void)
1207 extern char ** environ;
1208 if (environ) for (uschar ** p = USS environ; *p; p++)
1209 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1211 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
1212 exim_testharness_disable_ocsp_validity_check = TRUE;
1217 /**************************************************
1218 * One-time init credentials for server and client *
1219 **************************************************/
1222 creds_basic_init(gnutls_certificate_credentials_t x509_cred, BOOL server)
1224 #ifdef SUPPORT_SRV_OCSP_STACK
1225 gnutls_certificate_set_flags(x509_cred, GNUTLS_CERTIFICATE_API_V2);
1227 # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1228 if (server && tls_ocsp_file)
1230 if (f.running_in_test_harness)
1231 tls_server_testharness_ocsp_fiddle();
1233 if (exim_testharness_disable_ocsp_validity_check)
1234 gnutls_certificate_set_flags(x509_cred,
1235 GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
1240 debug_printf("TLS: basic cred init, %s\n", server ? "server" : "client");
1244 creds_load_server_certs(exim_gnutls_state_st * state, const uschar * cert,
1245 const uschar * pkey, const uschar * ocsp, uschar ** errstr)
1247 const uschar * clist = cert;
1248 const uschar * klist = pkey;
1249 const uschar * olist;
1250 int csep = 0, ksep = 0, osep = 0, cnt = 0, rc;
1251 uschar * cfile, * kfile, * ofile;
1252 #ifndef DISABLE_OCSP
1253 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1254 gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
1257 if (!expand_check(ocsp, US"tls_ocsp_file", &ofile, errstr))
1262 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1264 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1265 return tls_error(US"cert/key setup: out of keys", NULL, NULL, errstr);
1266 else if ((rc = tls_add_certfile(state, NULL, cfile, kfile, errstr)) > 0)
1270 int gnutls_cert_index = -rc;
1271 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
1272 gnutls_cert_index, cfile);
1274 #ifndef DISABLE_OCSP
1277 /* Set the OCSP stapling server info */
1278 if (gnutls_buggy_ocsp)
1281 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1283 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1285 DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n",
1286 gnutls_cert_index, ofile);
1287 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1288 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1290 ocsp_fmt = GNUTLS_X509_FMT_PEM;
1293 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1295 ocsp_fmt = GNUTLS_X509_FMT_DER;
1299 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1300 state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
1302 return tls_error_gnu(state,
1303 US"gnutls_certificate_set_ocsp_status_request_file2",
1306 debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
1308 /* Arrange callbacks for OCSP request observability */
1311 gnutls_handshake_set_hook_function(state->session,
1312 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1314 state->lib_state.ocsp_hook = TRUE;
1318 # if defined(SUPPORT_SRV_OCSP_STACK)
1319 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1320 state->lib_state.x509_cred, gnutls_cert_index,
1321 server_ocsp_stapling_cb, ofile)))
1322 return tls_error_gnu(state,
1323 US"gnutls_certificate_set_ocsp_status_request_function2",
1331 debug_printf("oops; multiple OCSP files not supported\n");
1334 gnutls_certificate_set_ocsp_status_request_function(
1335 state->lib_state.x509_cred, server_ocsp_stapling_cb, ofile);
1337 # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
1340 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1342 #endif /* DISABLE_OCSP */
1348 creds_load_client_certs(exim_gnutls_state_st * state, const host_item * host,
1349 const uschar * cert, const uschar * pkey, uschar ** errstr)
1351 int rc = tls_add_certfile(state, host, cert, pkey, errstr);
1352 if (rc > 0) return rc;
1353 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1358 creds_load_cabundle(exim_gnutls_state_st * state, const uschar * bundle,
1359 const host_item * host, uschar ** errstr)
1362 struct stat statbuf;
1364 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1365 if (Ustrcmp(bundle, "system") == 0 || Ustrncmp(bundle, "system,", 7) == 0)
1366 cert_count = gnutls_certificate_set_x509_system_trust(state->lib_state.x509_cred);
1370 if (Ustat(bundle, &statbuf) < 0)
1372 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' "
1373 "(tls_verify_certificates): %s", bundle, strerror(errno));
1377 #ifndef SUPPORT_CA_DIR
1378 /* The test suite passes in /dev/null; we could check for that path explicitly,
1379 but who knows if someone has some weird FIFO which always dumps some certs, or
1380 other weirdness. The thing we really want to check is that it's not a
1381 directory, since while OpenSSL supports that, GnuTLS does not.
1382 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1383 if (S_ISDIR(statbuf.st_mode))
1385 log_write(0, LOG_MAIN|LOG_PANIC,
1386 "tls_verify_certificates \"%s\" is a directory", bundle);
1391 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1392 bundle, statbuf.st_size);
1394 if (statbuf.st_size == 0)
1397 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1403 #ifdef SUPPORT_CA_DIR
1404 (statbuf.st_mode & S_IFMT) == S_IFDIR
1406 gnutls_certificate_set_x509_trust_dir(state->lib_state.x509_cred,
1407 CS bundle, GNUTLS_X509_FMT_PEM)
1410 gnutls_certificate_set_x509_trust_file(state->lib_state.x509_cred,
1411 CS bundle, GNUTLS_X509_FMT_PEM);
1413 #ifdef SUPPORT_CA_DIR
1414 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1415 when using the directory-of-certs config model. */
1417 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1419 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1421 state->lib_state.ca_rdn_emulate = TRUE;
1426 return tls_error_gnu(state, US"setting certificate trust", cert_count, errstr);
1428 debug_printf("Added %d certificate authorities\n", cert_count);
1435 creds_load_crl(exim_gnutls_state_st * state, const uschar * crl, uschar ** errstr)
1438 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
1439 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
1440 CS crl, GNUTLS_X509_FMT_PEM)) < 0)
1441 return tls_error_gnu(state, US"gnutls_certificate_set_x509_crl_file",
1442 cert_count, errstr);
1444 DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
1450 creds_load_pristring(exim_gnutls_state_st * state, const uschar * p,
1451 const char ** errpos)
1455 p = exim_default_gnutls_priority;
1457 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1459 return gnutls_priority_init( (gnutls_priority_t *) &state->lib_state.pri_cache,
1464 tls_server_creds_init(void)
1466 uschar * dummy_errstr;
1467 unsigned lifetime = 0;
1469 state_server.lib_state = null_tls_preload;
1470 if (gnutls_certificate_allocate_credentials(
1471 (gnutls_certificate_credentials_t *) &state_server.lib_state.x509_cred))
1473 state_server.lib_state.x509_cred = NULL;
1476 creds_basic_init(state_server.lib_state.x509_cred, TRUE);
1478 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1479 /* If tls_certificate has any $ indicating expansions, it is not good.
1480 If tls_privatekey is set but has $, not good. Likewise for tls_ocsp_file.
1481 If all good (and tls_certificate set), load the cert(s). */
1483 if ( opt_set_and_noexpand(tls_certificate)
1484 # ifndef DISABLE_OCSP
1485 && opt_unset_or_noexpand(tls_ocsp_file)
1487 && opt_unset_or_noexpand(tls_privatekey))
1489 /* Set watches on the filenames. The implementation does de-duplication
1490 so we can just blindly do them all.
1493 if ( tls_set_watch(tls_certificate, TRUE)
1494 # ifndef DISABLE_OCSP
1495 && tls_set_watch(tls_ocsp_file, TRUE)
1497 && tls_set_watch(tls_privatekey, TRUE))
1499 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1500 if (creds_load_server_certs(&state_server, tls_certificate,
1501 tls_privatekey && *tls_privatekey ? tls_privatekey : tls_certificate,
1502 # ifdef DISABLE_OCSP
1507 &dummy_errstr) == 0)
1508 state_server.lib_state.conn_certs = TRUE;
1511 else if ( !tls_certificate && !tls_privatekey
1512 # ifndef DISABLE_OCSP
1516 { /* Generate & preload a selfsigned cert. No files to watch. */
1517 if ((tls_install_selfsign(&state_server, &dummy_errstr)) == OK)
1519 state_server.lib_state.conn_certs = TRUE;
1520 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1524 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1526 /* If tls_verify_certificates is non-empty and has no $, load CAs */
1528 if (opt_set_and_noexpand(tls_verify_certificates))
1530 if (tls_set_watch(tls_verify_certificates, FALSE))
1532 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1533 if (creds_load_cabundle(&state_server, tls_verify_certificates,
1534 NULL, &dummy_errstr) != OK)
1536 state_server.lib_state.cabundle = TRUE;
1538 /* If CAs loaded and tls_crl is non-empty and has no $, load it */
1540 if (opt_set_and_noexpand(tls_crl))
1542 if (tls_set_watch(tls_crl, FALSE))
1544 DEBUG(D_tls) debug_printf("TLS: preloading CRL for server\n");
1545 if (creds_load_crl(&state_server, tls_crl, &dummy_errstr) != OK)
1547 state_server.lib_state.crl = TRUE;
1551 DEBUG(D_tls) debug_printf("TLS: not preloading CRL for server\n");
1555 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1556 #endif /* EXIM_HAVE_INOTIFY */
1558 /* If tls_require_ciphers is non-empty and has no $, load the
1559 ciphers priority cache. If unset, load with the default.
1560 (server-only as the client one depends on non/DANE) */
1562 if (!tls_require_ciphers || opt_set_and_noexpand(tls_require_ciphers))
1564 const char * dummy_errpos;
1565 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server: %s\n",
1566 tls_require_ciphers);
1567 if ( creds_load_pristring(&state_server, tls_require_ciphers, &dummy_errpos)
1569 state_server.lib_state.pri_string = TRUE;
1572 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1577 /* Preload whatever creds are static, onto a transport. The client can then
1578 just copy the pointer as it starts up. */
1581 tls_client_creds_init(transport_instance * t, BOOL watch)
1583 smtp_transport_options_block * ob = t->options_block;
1584 exim_gnutls_state_st tpt_dummy_state;
1585 host_item * dummy_host = (host_item *)1;
1586 uschar * dummy_errstr;
1588 if ( !exim_gnutls_base_init_done
1589 && tls_g_init(&dummy_errstr) != OK)
1592 ob->tls_preload = null_tls_preload;
1593 if (gnutls_certificate_allocate_credentials(
1594 (struct gnutls_certificate_credentials_st **)&ob->tls_preload.x509_cred))
1596 ob->tls_preload.x509_cred = NULL;
1599 creds_basic_init(ob->tls_preload.x509_cred, FALSE);
1601 tpt_dummy_state.session = NULL;
1602 tpt_dummy_state.lib_state = ob->tls_preload;
1604 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1605 if ( opt_set_and_noexpand(ob->tls_certificate)
1606 && opt_unset_or_noexpand(ob->tls_privatekey))
1609 || ( tls_set_watch(ob->tls_certificate, FALSE)
1610 && tls_set_watch(ob->tls_privatekey, FALSE)
1613 const uschar * pkey = ob->tls_privatekey;
1616 debug_printf("TLS: preloading client certs for transport '%s'\n", t->name);
1618 /* The state->lib_state.x509_cred is used for the certs load, and is the sole
1619 structure element used. So we can set up a dummy. The hoat arg only
1620 selects a retcode in case of fail, so any value */
1622 if (creds_load_client_certs(&tpt_dummy_state, dummy_host,
1623 ob->tls_certificate, pkey ? pkey : ob->tls_certificate,
1624 &dummy_errstr) == OK)
1625 ob->tls_preload.conn_certs = TRUE;
1630 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1632 if (opt_set_and_noexpand(ob->tls_verify_certificates))
1634 if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
1637 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1638 if (creds_load_cabundle(&tpt_dummy_state, ob->tls_verify_certificates,
1639 dummy_host, &dummy_errstr) != OK)
1641 ob->tls_preload.cabundle = TRUE;
1643 if (opt_set_and_noexpand(ob->tls_crl))
1645 if (!watch || tls_set_watch(ob->tls_crl, FALSE))
1647 DEBUG(D_tls) debug_printf("TLS: preloading CRL for transport '%s'\n", t->name);
1648 if (creds_load_crl(&tpt_dummy_state, ob->tls_crl, &dummy_errstr) != OK)
1650 ob->tls_preload.crl = TRUE;
1654 DEBUG(D_tls) debug_printf("TLS: not preloading CRL, for transport '%s'\n", t->name);
1659 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1661 /* We do not preload tls_require_ciphers to to the transport as it implicitly
1662 depends on DANE or plain usage. */
1668 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1669 /* Invalidate the creds cached, by dropping the current ones.
1670 Call when we notice one of the source files has changed. */
1673 tls_server_creds_invalidate(void)
1675 if (state_server.lib_state.pri_cache)
1676 gnutls_priority_deinit(state_server.lib_state.pri_cache);
1677 state_server.lib_state.pri_cache = NULL;
1679 if (state_server.lib_state.x509_cred)
1680 gnutls_certificate_free_credentials(state_server.lib_state.x509_cred);
1681 state_server.lib_state = null_tls_preload;
1686 tls_client_creds_invalidate(transport_instance * t)
1688 smtp_transport_options_block * ob = t->options_block;
1689 if (ob->tls_preload.x509_cred)
1690 gnutls_certificate_free_credentials(ob->tls_preload.x509_cred);
1691 ob->tls_preload = null_tls_preload;
1696 /*************************************************
1697 * Variables re-expanded post-SNI *
1698 *************************************************/
1700 /* Called from both server and client code, via tls_init(), and also from
1701 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
1703 We can tell the two apart by state->received_sni being non-NULL in callback.
1705 The callback should not call us unless state->trigger_sni_changes is true,
1706 which we are responsible for setting on the first pass through.
1709 state exim_gnutls_state_st *
1710 errstr error string pointer
1712 Returns: OK/DEFER/FAIL
1716 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
1719 const host_item *host = state->host; /* macro should be reconsidered? */
1720 const uschar *saved_tls_certificate = NULL;
1721 const uschar *saved_tls_privatekey = NULL;
1722 const uschar *saved_tls_verify_certificates = NULL;
1723 const uschar *saved_tls_crl = NULL;
1726 /* We check for tls_sni *before* expansion. */
1727 if (!host) /* server */
1728 if (!state->received_sni)
1730 if ( state->tls_certificate
1731 && ( Ustrstr(state->tls_certificate, US"tls_sni")
1732 || Ustrstr(state->tls_certificate, US"tls_in_sni")
1733 || Ustrstr(state->tls_certificate, US"tls_out_sni")
1736 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI\n");
1737 state->trigger_sni_changes = TRUE;
1740 else /* SNI callback case */
1742 /* useful for debugging */
1743 saved_tls_certificate = state->exp_tls_certificate;
1744 saved_tls_privatekey = state->exp_tls_privatekey;
1745 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1746 saved_tls_crl = state->exp_tls_crl;
1749 if (!state->lib_state.x509_cred)
1751 if ((rc = gnutls_certificate_allocate_credentials(
1752 (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))
1753 return tls_error_gnu(state, US"gnutls_certificate_allocate_credentials",
1755 creds_basic_init(state->lib_state.x509_cred, !host);
1759 /* remember: Expand_check_tlsvar() is expand_check() but fiddling with
1760 state members, assuming consistent naming; and expand_check() returns
1761 false if expansion failed, unless expansion was forced to fail. */
1763 /* check if we at least have a certificate, before doing expensive
1766 if (!state->lib_state.conn_certs)
1768 if (!Expand_check_tlsvar(tls_certificate, errstr))
1771 /* certificate is mandatory in server, optional in client */
1773 if ( !state->exp_tls_certificate
1774 || !*state->exp_tls_certificate
1777 return tls_install_selfsign(state, errstr);
1779 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1781 if (state->tls_privatekey && !Expand_check_tlsvar(tls_privatekey, errstr))
1784 /* tls_privatekey is optional, defaulting to same file as certificate */
1786 if (!state->tls_privatekey || !*state->tls_privatekey)
1788 state->tls_privatekey = state->tls_certificate;
1789 state->exp_tls_privatekey = state->exp_tls_certificate;
1792 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1795 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1796 state->exp_tls_certificate, state->exp_tls_privatekey);
1798 if (state->received_sni)
1799 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1800 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1803 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1804 load = FALSE; /* avoid re-loading the same certs */
1806 else /* unload the pre-SNI certs before loading new ones */
1808 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair\n");
1809 gnutls_certificate_free_keys(state->lib_state.x509_cred);
1814 ? creds_load_client_certs(state, host, state->exp_tls_certificate,
1815 state->exp_tls_privatekey, errstr)
1816 : creds_load_server_certs(state, state->exp_tls_certificate,
1817 state->exp_tls_privatekey,
1830 debug_printf("%s certs were preloaded\n", host ? "client" : "server");
1832 if (!state->tls_privatekey) state->tls_privatekey = state->tls_certificate;
1833 state->exp_tls_certificate = US state->tls_certificate;
1834 state->exp_tls_privatekey = US state->tls_privatekey;
1836 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1837 if (state->lib_state.ocsp_hook)
1838 gnutls_handshake_set_hook_function(state->session,
1839 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1844 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1845 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1846 error message is provided. However, if we just refrain from setting anything up
1847 in that case, certificate verification fails, which seems to be the correct
1850 if (!state->lib_state.cabundle)
1852 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1854 if (!Expand_check_tlsvar(tls_verify_certificates, errstr))
1856 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1857 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1858 state->exp_tls_verify_certificates = NULL;
1860 if (state->tls_crl && *state->tls_crl)
1861 if (!Expand_check_tlsvar(tls_crl, errstr))
1864 if (!(state->exp_tls_verify_certificates &&
1865 *state->exp_tls_verify_certificates))
1868 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1869 /* With no tls_verify_certificates, we ignore tls_crl too */
1876 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1879 rc = creds_load_cabundle(state, state->exp_tls_verify_certificates, host, errstr);
1880 if (rc != OK) return rc;
1885 debug_printf("%s CA bundle was preloaded\n", host ? "client" : "server");
1886 state->exp_tls_verify_certificates = US state->tls_verify_certificates;
1888 #ifdef SUPPORT_CA_DIR
1889 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1890 when using the directory-of-certs config model. */
1891 if (state->lib_state.ca_rdn_emulate)
1892 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1897 if (!state->lib_state.crl)
1899 if ( state->tls_crl && *state->tls_crl
1900 && state->exp_tls_crl && *state->exp_tls_crl)
1901 return creds_load_crl(state, state->exp_tls_crl, errstr);
1906 debug_printf("%s CRL was preloaded\n", host ? "client" : "server");
1907 state->exp_tls_crl = US state->tls_crl;
1916 /*************************************************
1917 * Set X.509 state variables *
1918 *************************************************/
1920 /* In GnuTLS, the registered cert/key are not replaced by a later
1921 set of a cert/key, so for SNI support we need a whole new x509_cred
1922 structure. Which means various other non-re-expanded pieces of state
1923 need to be re-set in the new struct, so the setting logic is pulled
1927 state exim_gnutls_state_st *
1928 errstr error string pointer
1930 Returns: OK/DEFER/FAIL
1934 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1937 const host_item *host = state->host; /* macro should be reconsidered? */
1939 #ifndef GNUTLS_AUTO_DHPARAMS
1940 /* Create D-H parameters, or read them from the cache file. This function does
1941 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1942 client-side params. */
1946 if (!dh_server_params)
1947 if ((rc = init_server_dh(errstr)) != OK) return rc;
1949 /* Unnecessary & discouraged with 3.6.0 or later */
1950 gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
1954 /* Link the credentials to the session. */
1956 if ((rc = gnutls_credentials_set(state->session,
1957 GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))
1958 return tls_error_gnu(state, US"gnutls_credentials_set", rc, errstr);
1963 /*************************************************
1964 * Initialize for GnuTLS *
1965 *************************************************/
1968 /* Called from both server and client code. In the case of a server, errors
1969 before actual TLS negotiation return DEFER.
1972 host connected host, if client; NULL if server
1973 ob tranport options block, if client; NULL if server
1974 require_ciphers tls_require_ciphers setting
1975 caller_state returned state-info structure
1976 errstr error string pointer
1978 Returns: OK/DEFER/FAIL
1983 const host_item *host,
1984 smtp_transport_options_block * ob,
1985 const uschar * require_ciphers,
1986 exim_gnutls_state_st **caller_state,
1990 exim_gnutls_state_st * state;
1994 if ( !exim_gnutls_base_init_done
1995 && (rc = tls_g_init(errstr)) != OK)
2000 /* For client-side sessions we allocate a context. This lets us run
2001 several in parallel. */
2003 int old_pool = store_pool;
2004 store_pool = POOL_PERM;
2005 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
2006 store_pool = old_pool;
2008 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2009 state->lib_state = ob->tls_preload;
2011 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
2012 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
2014 state->tls_certificate = ob->tls_certificate;
2015 state->tls_privatekey = ob->tls_privatekey;
2016 state->tls_sni = ob->tls_sni;
2017 state->tls_verify_certificates = ob->tls_verify_certificates;
2018 state->tls_crl = ob->tls_crl;
2022 /* Server operations always use the one state_server context. It is not
2023 shared because we have forked a fresh process for every receive. However it
2024 can get re-used for successive TLS sessions on a single TCP connection. */
2026 state = &state_server;
2028 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
2029 rc = gnutls_init(&state->session, GNUTLS_SERVER);
2031 state->tls_certificate = tls_certificate;
2032 state->tls_privatekey = tls_privatekey;
2033 state->tls_sni = NULL;
2034 state->tls_verify_certificates = tls_verify_certificates;
2035 state->tls_crl = tls_crl;
2038 return tls_error_gnu(state, US"gnutls_init", rc, errstr);
2040 state->tls_require_ciphers = require_ciphers;
2043 /* This handles the variables that might get re-expanded after TLS SNI;
2044 tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
2047 debug_printf("Expanding various TLS configuration options for session credentials\n");
2048 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
2050 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
2051 requires a new structure afterwards. */
2053 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
2055 /* set SNI in client, only */
2058 if (!expand_check(state->tls_sni, US"tls_out_sni", &state->tlsp->sni, errstr))
2060 if (state->tlsp->sni && *state->tlsp->sni)
2063 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
2064 sz = Ustrlen(state->tlsp->sni);
2065 if ((rc = gnutls_server_name_set(state->session,
2066 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
2067 return tls_error_gnu(state, US"gnutls_server_name_set", rc, errstr);
2070 else if (state->tls_sni)
2071 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
2072 "have an SNI set for a server [%s]\n", state->tls_sni);
2074 if (!state->lib_state.pri_string)
2076 const uschar * p = NULL;
2077 const char * errpos;
2079 /* This is the priority string support,
2080 http://www.gnutls.org/manual/html_node/Priority-Strings.html
2081 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
2082 This was backwards incompatible, but means Exim no longer needs to track
2083 all algorithms and provide string forms for them. */
2085 if (state->tls_require_ciphers && *state->tls_require_ciphers)
2087 if (!Expand_check_tlsvar(tls_require_ciphers, errstr))
2089 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
2091 p = state->exp_tls_require_ciphers;
2092 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
2096 if ((rc = creds_load_pristring(state, p, &errpos)))
2097 return tls_error_gnu(state, string_sprintf(
2098 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
2099 p, errpos - CS p, errpos),
2104 DEBUG(D_tls) debug_printf("cipher list preloaded\n");
2105 state->exp_tls_require_ciphers = US state->tls_require_ciphers;
2109 if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))
2110 return tls_error_gnu(state, US"gnutls_priority_set", rc, errstr);
2112 /* This also sets the server ticket expiration time to the same, and
2113 the STEK rotation time to 3x. */
2115 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
2117 /* Reduce security in favour of increased compatibility, if the admin
2118 decides to make that trade-off. */
2119 if (gnutls_compat_mode)
2121 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
2122 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
2123 gnutls_session_enable_compatibility_mode(state->session);
2125 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
2129 *caller_state = state;
2135 /*************************************************
2136 * Extract peer information *
2137 *************************************************/
2139 static const uschar *
2140 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
2141 gnutls_mac_algorithm_t mac)
2144 gnutls_kx_algorithm_t kx_i;
2145 gnutls_cipher_algorithm_t cipher_i;
2146 gnutls_mac_algorithm_t mac_i;
2149 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
2151 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
2152 return cipher_stdname(cs_id[0], cs_id[1]);
2158 /* Called from both server and client code.
2159 Only this is allowed to set state->peerdn and state->have_set_peerdn
2160 and we use that to detect double-calls.
2162 NOTE: the state blocks last while the TLS connection is up, which is fine
2163 for logging in the server side, but for the client side, we log after teardown
2164 in src/deliver.c. While the session is up, we can twist about states and
2165 repoint tls_* globals, but those variables used for logging or other variable
2166 expansion that happens _after_ delivery need to have a longer life-time.
2168 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
2169 doing this more than once per generation of a state context. We set them in
2170 the state context, and repoint tls_* to them. After the state goes away, the
2171 tls_* copies of the pointers remain valid and client delivery logging is happy.
2173 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
2177 state exim_gnutls_state_st *
2178 errstr pointer to error string
2180 Returns: OK/DEFER/FAIL
2184 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
2186 gnutls_session_t session = state->session;
2187 const gnutls_datum_t * cert_list;
2189 unsigned int cert_list_size = 0;
2190 gnutls_protocol_t protocol;
2191 gnutls_cipher_algorithm_t cipher;
2192 gnutls_kx_algorithm_t kx;
2193 gnutls_mac_algorithm_t mac;
2194 gnutls_certificate_type_t ct;
2195 gnutls_x509_crt_t crt;
2199 if (state->have_set_peerdn)
2201 state->have_set_peerdn = TRUE;
2203 state->peerdn = NULL;
2206 cipher = gnutls_cipher_get(session);
2207 protocol = gnutls_protocol_get_version(session);
2208 mac = gnutls_mac_get(session);
2210 #ifdef GNUTLS_TLS1_3
2211 protocol >= GNUTLS_TLS1_3 ? 0 :
2213 gnutls_kx_get(session);
2215 old_pool = store_pool;
2217 tls_support * tlsp = state->tlsp;
2218 store_pool = POOL_PERM;
2220 #ifdef SUPPORT_GNUTLS_SESS_DESC
2223 uschar * s = US gnutls_session_get_desc(session), c;
2225 /* Nikos M suggests we use this by preference. It returns like:
2226 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
2228 For partial back-compat, put a colon after the TLS version, replace the
2229 )-( grouping with __, replace in-group - with _ and append the :keysize. */
2231 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
2233 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
2235 tlsp->ver = string_copyn(g->s, g->ptr);
2236 for (uschar * p = US tlsp->ver; *p; p++)
2237 if (*p == '-') { *p = '\0'; break; } /* TLS1.0-PKIX -> TLS1.0 */
2239 g = string_catn(g, US":", 1);
2240 if (*s) s++; /* now on _ between groups */
2243 for (*++s && ++s; (c = *s) && c != ')'; s++)
2244 g = string_catn(g, c == '-' ? US"_" : s, 1);
2245 /* now on ) closing group */
2246 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
2247 /* now on _ between groups */
2249 g = string_catn(g, US":", 1);
2250 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
2251 state->ciphersuite = string_from_gstring(g);
2254 state->ciphersuite = string_sprintf("%s:%s:%d",
2255 gnutls_protocol_get_name(protocol),
2256 gnutls_cipher_suite_get_name(kx, cipher, mac),
2257 (int) gnutls_cipher_get_key_size(cipher) * 8);
2259 /* I don't see a way that spaces could occur, in the current GnuTLS
2260 code base, but it was a concern in the old code and perhaps older GnuTLS
2261 releases did return "TLS 1.0"; play it safe, just in case. */
2263 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
2264 tlsp->ver = string_copyn(state->ciphersuite,
2265 Ustrchr(state->ciphersuite, ':') - state->ciphersuite);
2268 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
2270 tlsp->cipher = state->ciphersuite;
2271 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
2273 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
2275 store_pool = old_pool;
2278 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
2280 if (!cert_list || cert_list_size == 0)
2282 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
2283 cert_list, cert_list_size);
2284 if (state->verify_requirement >= VERIFY_REQUIRED)
2285 return tls_error(US"certificate verification failed",
2286 US"no certificate received from peer", state->host, errstr);
2290 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
2292 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
2294 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
2295 if (state->verify_requirement >= VERIFY_REQUIRED)
2296 return tls_error(US"certificate verification not possible, unhandled type",
2297 ctn, state->host, errstr);
2301 #define exim_gnutls_peer_err(Label) \
2303 if (rc != GNUTLS_E_SUCCESS) \
2305 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
2306 (Label), gnutls_strerror(rc)); \
2307 if (state->verify_requirement >= VERIFY_REQUIRED) \
2308 return tls_error_gnu(state, (Label), rc, errstr); \
2313 rc = import_cert(&cert_list[0], &crt);
2314 exim_gnutls_peer_err(US"cert 0");
2316 state->tlsp->peercert = state->peercert = crt;
2319 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
2320 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
2322 exim_gnutls_peer_err(US"getting size for cert DN failed");
2323 return FAIL; /* should not happen */
2325 dn_buf = store_get_perm(sz, TRUE); /* tainted */
2326 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
2327 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
2329 state->peerdn = dn_buf;
2332 #undef exim_gnutls_peer_err
2338 /*************************************************
2339 * Verify peer certificate *
2340 *************************************************/
2342 /* Called from both server and client code.
2343 *Should* be using a callback registered with
2344 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
2345 the peer information, but that's too new for some OSes.
2348 state exim_gnutls_state_st *
2349 errstr where to put an error message
2352 FALSE if the session should be rejected
2353 TRUE if the cert is okay or we just don't care
2357 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
2362 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
2364 rc = peer_status(state, errstr);
2366 if (state->verify_requirement == VERIFY_NONE)
2369 if (rc != OK || !state->peerdn)
2371 verify = GNUTLS_CERT_INVALID;
2372 *errstr = US"certificate not supplied";
2378 if (state->verify_requirement == VERIFY_DANE && state->host)
2380 /* Using dane_verify_session_crt() would be easy, as it does it all for us
2381 including talking to a DNS resolver. But we want to do that bit ourselves
2382 as the testsuite intercepts and fakes its own DNS environment. */
2387 const gnutls_datum_t * certlist =
2388 gnutls_certificate_get_peers(state->session, &lsize);
2389 int usage = tls_out.tlsa_usage;
2391 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2392 /* Split the TLSA records into two sets, TA and EE selectors. Run the
2393 dane-verification separately so that we know which selector verified;
2394 then we know whether to do name-verification (needed for TA but not EE). */
2396 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
2397 { /* a mixed-usage bundle */
2402 for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
2405 dd = store_get(nrec * sizeof(uschar *), FALSE);
2406 ddl = store_get(nrec * sizeof(int), FALSE);
2409 if ((rc = dane_state_init(&s, 0)))
2412 for (usage = DANESSL_USAGE_DANE_EE;
2413 usage >= DANESSL_USAGE_DANE_TA; usage--)
2414 { /* take records with this usage */
2415 for (j = i = 0; i < nrec; i++)
2416 if (state->dane_data[i][0] == usage)
2418 dd[j] = state->dane_data[i];
2419 ddl[j++] = state->dane_data_len[i];
2426 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
2429 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
2430 gnutls_certificate_type_get(state->session),
2432 usage == DANESSL_USAGE_DANE_EE
2433 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2437 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
2439 else if (verify == 0) /* verification passed */
2447 if (rc) goto tlsa_prob;
2452 if ( (rc = dane_state_init(&s, 0))
2453 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
2455 || (rc = dane_verify_crt_raw(s, certlist, lsize,
2456 gnutls_certificate_type_get(state->session),
2458 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2459 usage == (1 << DANESSL_USAGE_DANE_EE)
2460 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2469 if (verify != 0) /* verification failed */
2472 (void) dane_verification_status_print(verify, &str, 0);
2473 *errstr = US str.data; /* don't bother to free */
2477 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2478 /* If a TA-mode TLSA record was used for verification we must additionally
2479 verify the cert name (but not the CA chain). For EE-mode, skip it. */
2481 if (usage & (1 << DANESSL_USAGE_DANE_EE))
2484 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2487 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2488 /* Assume that the name on the A-record is the one that should be matching
2489 the cert. An alternate view is that the domain part of the email address
2490 is also permissible. */
2492 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2493 CS state->host->name))
2495 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2500 #endif /*SUPPORT_DANE*/
2502 rc = gnutls_certificate_verify_peers2(state->session, &verify);
2505 /* Handle the result of verification. INVALID is set if any others are. */
2507 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
2509 state->peer_cert_verified = FALSE;
2512 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
2517 if (gnutls_certificate_verification_status_print(verify,
2518 gnutls_certificate_type_get(state->session), &txt, 0)
2519 == GNUTLS_E_SUCCESS)
2521 debug_printf("%s\n", txt.data);
2522 gnutls_free(txt.data);
2526 *errstr = verify & GNUTLS_CERT_REVOKED
2527 ? US"certificate revoked" : US"certificate invalid";
2531 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
2532 *errstr, state->peerdn ? state->peerdn : US"<unset>");
2534 if (state->verify_requirement >= VERIFY_REQUIRED)
2537 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
2542 /* Client side, check the server's certificate name versus the name on the
2543 A-record for the connection we made. What to do for server side - what name
2544 to use for client? We document that there is no such checking for server
2547 if ( state->exp_tls_verify_cert_hostnames
2548 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2549 CS state->exp_tls_verify_cert_hostnames)
2553 debug_printf("TLS certificate verification failed: cert name mismatch\n");
2554 if (state->verify_requirement >= VERIFY_REQUIRED)
2559 state->peer_cert_verified = TRUE;
2560 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
2561 state->peerdn ? state->peerdn : US"<unset>");
2565 state->tlsp->peerdn = state->peerdn;
2570 *errstr = string_sprintf("TLSA record problem: %s",
2571 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
2575 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
2582 /* ------------------------------------------------------------------------ */
2585 /* Logging function which can be registered with
2586 * gnutls_global_set_log_function()
2587 * gnutls_global_set_log_level() 0..9
2589 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2591 exim_gnutls_logger_cb(int level, const char *message)
2593 size_t len = strlen(message);
2596 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2599 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2600 message[len-1] == '\n' ? "" : "\n");
2605 /* Called after client hello, should handle SNI work.
2606 This will always set tls_sni (state->received_sni) if available,
2607 and may trigger presenting different certificates,
2608 if state->trigger_sni_changes is TRUE.
2610 Should be registered with
2611 gnutls_handshake_set_post_client_hello_function()
2613 "This callback must return 0 on success or a gnutls error code to terminate the
2616 For inability to get SNI information, we return 0.
2617 We only return non-zero if re-setup failed.
2618 Only used for server-side TLS.
2622 exim_sni_handling_cb(gnutls_session_t session)
2624 char sni_name[MAX_HOST_LEN];
2625 size_t data_len = MAX_HOST_LEN;
2626 exim_gnutls_state_st *state = &state_server;
2627 unsigned int sni_type;
2629 uschar * dummy_errstr;
2631 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2632 if (rc != GNUTLS_E_SUCCESS)
2635 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2636 debug_printf("TLS: no SNI presented in handshake\n");
2638 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2639 gnutls_strerror(rc), rc);
2643 if (sni_type != GNUTLS_NAME_DNS)
2645 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2649 /* We now have a UTF-8 string in sni_name */
2650 old_pool = store_pool;
2651 store_pool = POOL_PERM;
2652 state->received_sni = string_copy_taint(US sni_name, TRUE);
2653 store_pool = old_pool;
2655 /* We set this one now so that variable expansions below will work */
2656 state->tlsp->sni = state->received_sni;
2658 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2659 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2661 if (!state->trigger_sni_changes)
2664 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2666 /* If the setup of certs/etc failed before handshake, TLS would not have
2667 been offered. The best we can do now is abort. */
2668 return GNUTLS_E_APPLICATION_ERROR_MIN;
2671 rc = tls_set_remaining_x509(state, &dummy_errstr);
2672 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2679 #ifndef DISABLE_EVENT
2681 We use this callback to get observability and detail-level control
2682 for an exim TLS connection (either direction), raising a tls:cert event
2683 for each cert in the chain presented by the peer. Any event
2684 can deny verification.
2686 Return 0 for the handshake to continue or non-zero to terminate.
2690 verify_cb(gnutls_session_t session)
2692 const gnutls_datum_t * cert_list;
2693 unsigned int cert_list_size = 0;
2694 gnutls_x509_crt_t crt;
2697 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2699 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2700 while (cert_list_size--)
2702 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2704 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2705 cert_list_size, gnutls_strerror(rc));
2709 state->tlsp->peercert = crt;
2710 if ((yield = event_raise(state->event_action,
2711 US"tls:cert", string_sprintf("%d", cert_list_size))))
2713 log_write(0, LOG_MAIN,
2714 "SSL verify denied by event-action: depth=%d: %s",
2715 cert_list_size, yield);
2716 return 1; /* reject */
2718 state->tlsp->peercert = NULL;
2728 ddump(gnutls_datum_t * d)
2730 gstring * g = string_get((d->size+1) * 2);
2731 uschar * s = d->data;
2732 for (unsigned i = d->size; i > 0; i--, s++)
2734 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2735 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2741 post_handshake_debug(exim_gnutls_state_st * state)
2743 #ifdef SUPPORT_GNUTLS_SESS_DESC
2744 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2747 #ifdef SUPPORT_GNUTLS_KEYLOG
2748 # ifdef EXIM_HAVE_TLS1_3
2749 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2754 gnutls_datum_t c, s;
2756 /* For TLS1.2 we only want the client random and the master secret */
2757 gnutls_session_get_random(state->session, &c, &s);
2758 gnutls_session_get_master_secret(state->session, &s);
2761 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2764 debug_printf("To get keying info for TLS1.3 is hard:\n"
2765 " Set environment variable SSLKEYLOGFILE to a filename relative to the spool directory,\n"
2766 " and make sure it is writable by the Exim runtime user.\n"
2767 " Add SSLKEYLOGFILE to keep_environment in the exim config.\n"
2768 " Start Exim as root.\n"
2769 " If using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
2770 " (works for TLS1.2 also, and saves cut-paste into file).\n"
2771 " Trying to use add_environment for this will not work\n");
2776 #ifdef EXIM_HAVE_TLS_RESUME
2778 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2779 unsigned incoming, const gnutls_datum_t * msg)
2781 DEBUG(D_tls) debug_printf("newticket cb\n");
2782 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2787 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2789 /* Should the server offer session resumption? */
2790 tls_in.resumption = RESUME_SUPPORTED;
2791 if (verify_check_host(&tls_resumption_hosts) == OK)
2794 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2795 an offered resumption is unacceptable. We lose one resumption per ticket
2796 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2797 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2798 least they go out in a single packet. */
2800 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2801 &server_sessticket_key)))
2802 tls_in.resumption |= RESUME_SERVER_TICKET;
2805 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2807 /* Try to tell if we see a ticket request */
2808 gnutls_handshake_set_hook_function(state->session,
2809 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2814 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2816 if (gnutls_session_resumption_requested(state->session))
2818 /* This tells us the client sent a full ticket. We use a
2819 callback on session-ticket request, elsewhere, to tell
2820 if a client asked for a ticket. */
2822 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2823 DEBUG(D_tls) debug_printf("client requested resumption\n");
2825 if (gnutls_session_is_resumed(state->session))
2827 tls_in.resumption |= RESUME_USED;
2828 DEBUG(D_tls) debug_printf("Session resumed\n");
2831 #endif /* EXIM_HAVE_TLS_RESUME */
2834 #ifdef EXIM_HAVE_ALPN
2835 /* Expand and convert an Exim list to a gnutls_datum list. False return for fail.
2836 NULL plist return for silent no-ALPN.
2840 tls_alpn_plist(const uschar * tls_alpn, const gnutls_datum_t ** plist, unsigned * plen,
2845 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
2850 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
2855 const uschar * list = exp_alpn;
2861 while (string_nextinlist(&list, &sep, NULL, 0)) cnt++;
2863 p = store_get(sizeof(gnutls_datum_t) * cnt, is_tainted(exp_alpn));
2865 for (int i = 0; s = string_nextinlist(&list, &sep, NULL, 0); i++)
2866 { p[i].data = s; p[i].size = Ustrlen(s); }
2867 *plist = (*plen = cnt) ? p : NULL;
2873 tls_server_set_acceptable_alpns(exim_gnutls_state_st * state, uschar ** errstr)
2876 const gnutls_datum_t * plist;
2879 if (tls_alpn_plist(tls_alpn, &plist, &plen, errstr) && plist)
2881 /* This seems to be only mandatory if the client sends an ALPN extension;
2882 not trying ALPN is ok. Need to decide how to support server-side must-alpn. */
2884 server_seen_alpn = 0;
2885 if (!(rc = gnutls_alpn_set_protocols(state->session, plist, plen,
2886 GNUTLS_ALPN_MANDATORY)))
2887 gnutls_handshake_set_hook_function(state->session,
2888 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2891 debug_printf("setting alpn protocols: %s\n", US gnutls_strerror(rc));
2894 #endif /* EXIM_HAVE_ALPN */
2896 /* ------------------------------------------------------------------------ */
2897 /* Exported functions */
2902 /*************************************************
2903 * Start a TLS session in a server *
2904 *************************************************/
2906 /* This is called when Exim is running as a server, after having received
2907 the STARTTLS command. It must respond to that command, and then negotiate
2911 errstr pointer to error string
2913 Returns: OK on success
2914 DEFER for errors before the start of the negotiation
2915 FAIL for errors during the negotiation; the server can't
2920 tls_server_start(uschar ** errstr)
2923 exim_gnutls_state_st * state = NULL;
2925 /* Check for previous activation */
2926 if (tls_in.active.sock >= 0)
2928 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2929 smtp_printf("554 Already in TLS\r\n", FALSE);
2933 /* Initialize the library. If it fails, it will already have logged the error
2934 and sent an SMTP response. */
2936 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2939 #ifdef MEASURE_TIMING
2941 gettimeofday(&t0, NULL);
2944 if ((rc = tls_init(NULL, NULL,
2945 tls_require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2947 #ifdef MEASURE_TIMING
2948 report_time_since(&t0, US"server tls_init (delta)");
2952 #ifdef EXIM_HAVE_ALPN
2953 tls_server_set_acceptable_alpns(state, errstr);
2956 #ifdef EXIM_HAVE_TLS_RESUME
2957 tls_server_resume_prehandshake(state);
2960 /* If this is a host for which certificate verification is mandatory or
2961 optional, set up appropriately. */
2963 if (verify_check_host(&tls_verify_hosts) == OK)
2966 debug_printf("TLS: a client certificate will be required\n");
2967 state->verify_requirement = VERIFY_REQUIRED;
2968 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2970 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2973 debug_printf("TLS: a client certificate will be requested but not required\n");
2974 state->verify_requirement = VERIFY_OPTIONAL;
2975 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2980 debug_printf("TLS: a client certificate will not be requested\n");
2981 state->verify_requirement = VERIFY_NONE;
2982 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2985 #ifndef DISABLE_EVENT
2988 state->event_action = event_action;
2989 gnutls_session_set_ptr(state->session, state);
2990 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
2994 /* Register SNI handling; always, even if not in tls_certificate, so that the
2995 expansion variable $tls_sni is always available. */
2997 gnutls_handshake_set_post_client_hello_function(state->session,
2998 exim_sni_handling_cb);
3000 /* Set context and tell client to go ahead, except in the case of TLS startup
3001 on connection, where outputting anything now upsets the clients and tends to
3002 make them disconnect. We need to have an explicit fflush() here, to force out
3003 the response. Other smtp_printf() calls do not need it, because in non-TLS
3004 mode, the fflush() happens when smtp_getc() is called. */
3006 if (!state->tlsp->on_connect)
3008 smtp_printf("220 TLS go ahead\r\n", FALSE);
3012 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3013 that the GnuTLS library doesn't.
3014 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
3015 to set (and clear down afterwards) up a pull-timeout callback function that does
3016 a select, so we're no better off unless avoiding signals becomes an issue. */
3018 gnutls_transport_set_ptr2(state->session,
3019 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
3020 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
3021 state->fd_in = fileno(smtp_in);
3022 state->fd_out = fileno(smtp_out);
3024 sigalrm_seen = FALSE;
3025 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3027 rc = gnutls_handshake(state->session);
3028 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3031 if (rc != GNUTLS_E_SUCCESS)
3033 /* It seems that, except in the case of a timeout, we have to close the
3034 connection right here; otherwise if the other end is running OpenSSL it hangs
3035 until the server times out. */
3039 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
3040 gnutls_db_remove_session(state->session);
3044 tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
3045 (void) gnutls_alert_send_appropriate(state->session, rc);
3046 gnutls_deinit(state->session);
3047 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3048 state->lib_state = null_tls_preload;
3050 shutdown(state->fd_out, SHUT_WR);
3051 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
3052 (void)fclose(smtp_out);
3053 (void)fclose(smtp_in);
3054 smtp_out = smtp_in = NULL;
3060 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3061 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3062 tls_in.ext_master_secret = TRUE;
3065 #ifdef EXIM_HAVE_TLS_RESUME
3066 tls_server_resume_posthandshake(state);
3069 DEBUG(D_tls) post_handshake_debug(state);
3071 #ifdef EXIM_HAVE_ALPN
3072 if (server_seen_alpn > 0)
3075 { /* The client offered ALPN. See what was negotiated. */
3076 gnutls_datum_t p = {.size = 0};
3077 int rc = gnutls_alpn_get_selected_protocol(state->session, &p);
3079 debug_printf("ALPN negotiated: %.*s\n", (int)p.size, p.data);
3081 debug_printf("getting alpn protocol: %s\n", US gnutls_strerror(rc));
3085 else if (server_seen_alpn == 0)
3086 if (verify_check_host(&hosts_require_alpn) == OK)
3088 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
3089 tls_error(US"handshake", US"ALPN required but not negotiated", NULL, errstr);
3093 DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n");
3095 DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n");
3098 /* Verify after the fact */
3100 if (!verify_certificate(state, errstr))
3102 if (state->verify_requirement != VERIFY_OPTIONAL)
3104 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
3108 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
3112 /* Sets various Exim expansion variables; always safe within server */
3114 extract_exim_vars_from_tls_state(state);
3116 /* TLS has been set up. Adjust the input functions to read via TLS,
3117 and initialize appropriately. */
3119 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3121 receive_getc = tls_getc;
3122 receive_getbuf = tls_getbuf;
3123 receive_get_cache = tls_get_cache;
3124 receive_ungetc = tls_ungetc;
3125 receive_feof = tls_feof;
3126 receive_ferror = tls_ferror;
3127 receive_smtp_buffered = tls_smtp_buffered;
3136 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
3137 smtp_transport_options_block * ob)
3139 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3141 state->exp_tls_verify_cert_hostnames =
3143 string_domain_utf8_to_alabel(host->certname, NULL);
3148 debug_printf("TLS: server cert verification includes hostname: \"%s\"\n",
3149 state->exp_tls_verify_cert_hostnames);
3157 /* Given our list of RRs from the TLSA lookup, build a lookup block in
3158 GnuTLS-DANE's preferred format. Hang it on the state str for later
3159 use in DANE verification.
3161 We point at the dnsa data not copy it, so it must remain valid until
3162 after verification is done.*/
3165 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
3169 const char ** dane_data;
3170 int * dane_data_len;
3173 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3174 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3175 ) if (rr->type == T_TLSA) i++;
3177 dane_data = store_get(i * sizeof(uschar *), FALSE);
3178 dane_data_len = store_get(i * sizeof(int), FALSE);
3181 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3182 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3183 ) if (rr->type == T_TLSA && rr->size > 3)
3185 const uschar * p = rr->data;
3186 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
3187 uint8_t usage = p[0], sel = p[1], type = p[2];
3190 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
3192 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
3193 || (sel != 0 && sel != 1)
3198 case 0: /* Full: cannot check at present */
3200 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
3202 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
3207 tls_out.tlsa_usage |= 1<<usage;
3208 dane_data[i] = CS p;
3209 dane_data_len[i++] = rr->size;
3212 if (!i) return FALSE;
3214 dane_data[i] = NULL;
3215 dane_data_len[i] = 0;
3217 state->dane_data = (char * const *)dane_data;
3218 state->dane_data_len = dane_data_len;
3225 #ifdef EXIM_HAVE_TLS_RESUME
3226 /* On the client, get any stashed session for the given IP from hints db
3227 and apply it to the ssl-connection for attempted resumption. Although
3228 there is a gnutls_session_ticket_enable_client() interface it is
3229 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
3230 by deafult". There seems to be no way to disable them, so even hosts not
3231 enabled by the transport option will be sent a ticket request. We will
3232 however avoid storing and retrieving session information. */
3235 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
3236 host_item * host, smtp_transport_options_block * ob)
3238 tlsp->resumption = RESUME_SUPPORTED;
3239 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3241 dbdata_tls_session * dt;
3243 open_db dbblock, * dbm_file;
3246 debug_printf("check for resumable session for %s\n", host->address);
3247 tlsp->host_resumable = TRUE;
3248 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3249 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
3251 /* Key for the db is the IP. We'd like to filter the retrieved session
3252 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
3254 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
3255 if (!(rc = gnutls_session_set_data(session,
3256 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
3258 DEBUG(D_tls) debug_printf("good session\n");
3259 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3261 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
3262 US gnutls_strerror(rc));
3263 dbfn_close(dbm_file);
3270 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
3272 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
3273 but this flag is not set until the second. TLS 1.3 it's the other way about.
3274 Keep both calls as the session data cannot be extracted before handshake
3277 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
3282 DEBUG(D_tls) debug_printf("server offered session ticket\n");
3283 tlsp->ticket_received = TRUE;
3284 tlsp->resumption |= RESUME_SERVER_TICKET;
3286 if (tlsp->host_resumable)
3287 if (!(rc = gnutls_session_get_data2(session, &tkt)))
3289 open_db dbblock, * dbm_file;
3290 int dlen = sizeof(dbdata_tls_session) + tkt.size;
3291 dbdata_tls_session * dt = store_get(dlen, TRUE);
3293 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
3294 memcpy(dt->session, tkt.data, tkt.size);
3295 gnutls_free(tkt.data);
3297 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3299 /* key for the db is the IP */
3300 dbfn_delete(dbm_file, host->address);
3301 dbfn_write(dbm_file, host->address, dt, dlen);
3302 dbfn_close(dbm_file);
3305 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
3309 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
3314 /* With a TLS1.3 session, the ticket(s) are not seen until
3315 the first data read is attempted. And there's often two of them.
3316 Pick them up with this callback. We are also called for 1.2
3320 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
3321 unsigned incoming, const gnutls_datum_t * msg)
3323 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
3324 tls_support * tlsp = state->tlsp;
3326 DEBUG(D_tls) debug_printf("newticket cb\n");
3328 if (!tlsp->ticket_received)
3329 tls_save_session(tlsp, sess, state->host);
3335 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
3336 tls_support * tlsp, host_item * host,
3337 smtp_transport_options_block * ob)
3339 gnutls_session_set_ptr(state->session, state);
3340 gnutls_handshake_set_hook_function(state->session,
3341 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
3343 tls_retrieve_session(tlsp, state->session, host, ob);
3347 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
3348 tls_support * tlsp, host_item * host)
3350 if (gnutls_session_is_resumed(state->session))
3352 DEBUG(D_tls) debug_printf("Session resumed\n");
3353 tlsp->resumption |= RESUME_USED;
3356 tls_save_session(tlsp, state->session, host);
3358 #endif /* !DISABLE_TLS_RESUME */
3361 /*************************************************
3362 * Start a TLS session in a client *
3363 *************************************************/
3365 /* Called from the smtp transport after STARTTLS has been accepted.
3368 cctx connection context
3369 conn_args connection details
3370 cookie datum for randomness (not used)
3371 tlsp record details of channel configuration here; must be non-NULL
3372 errstr error string pointer
3374 Returns: TRUE for success with TLS session context set in smtp context,
3379 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3380 void * cookie ARG_UNUSED,
3381 tls_support * tlsp, uschar ** errstr)
3383 host_item * host = conn_args->host; /* for msgs and option-tests */
3384 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3385 smtp_transport_options_block * ob = tb
3386 ? (smtp_transport_options_block *)tb->options_block
3387 : &smtp_transport_option_defaults;
3389 exim_gnutls_state_st * state = NULL;
3390 uschar * cipher_list = NULL;
3392 #ifndef DISABLE_OCSP
3394 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3395 BOOL request_ocsp = require_ocsp ? TRUE
3396 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3399 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
3402 /* If dane is flagged, have either request or require dane for this host, and
3403 a TLSA record found. Therefore, dane verify required. Which implies cert must
3404 be requested and supplied, dane verify must pass, and cert verify irrelevant
3405 (incl. hostnames), and (caller handled) require_tls and sni=$domain */
3407 if (conn_args->dane && ob->dane_require_tls_ciphers)
3409 /* not using Expand_check_tlsvar because not yet in state */
3410 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3411 &cipher_list, errstr))
3413 cipher_list = cipher_list && *cipher_list
3414 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
3419 cipher_list = ob->tls_require_ciphers;
3422 #ifdef MEASURE_TIMING
3424 gettimeofday(&t0, NULL);
3427 if (tls_init(host, ob, cipher_list, &state, tlsp, errstr) != OK)
3430 #ifdef MEASURE_TIMING
3431 report_time_since(&t0, US"client tls_init (delta)");
3436 #ifdef EXIM_HAVE_ALPN
3438 const gnutls_datum_t * plist;
3441 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
3444 if (gnutls_alpn_set_protocols(state->session, plist, plen, 0) != 0)
3446 tls_error(US"alpn init", NULL, state->host, errstr);
3450 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
3453 log_write(0, LOG_MAIN, "ALPN unusable with this GnuTLS library version; ignoring \"%s\"\n",
3458 int dh_min_bits = ob->tls_dh_min_bits;
3459 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
3462 debug_printf("WARNING: tls_dh_min_bits far too low,"
3463 " clamping %d up to %d\n",
3464 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
3465 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
3468 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
3469 " acceptable bits to %d\n",
3471 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
3474 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
3475 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
3476 the specified host patterns if one of them is defined */
3479 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
3482 debug_printf("TLS: server certificate DANE required\n");
3483 state->verify_requirement = VERIFY_DANE;
3484 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3488 if ( ( state->exp_tls_verify_certificates
3489 && !ob->tls_verify_hosts
3490 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
3492 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3495 tls_client_setup_hostname_checks(host, state, ob);
3497 debug_printf("TLS: server certificate verification required\n");
3498 state->verify_requirement = VERIFY_REQUIRED;
3499 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3501 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3503 tls_client_setup_hostname_checks(host, state, ob);
3505 debug_printf("TLS: server certificate verification optional\n");
3506 state->verify_requirement = VERIFY_OPTIONAL;
3507 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
3512 debug_printf("TLS: server certificate verification not required\n");
3513 state->verify_requirement = VERIFY_NONE;
3514 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
3517 #ifndef DISABLE_OCSP
3518 /* supported since GnuTLS 3.1.3 */
3521 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
3522 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
3523 NULL, 0, NULL)) != OK)
3525 tls_error_gnu(state, US"cert-status-req", rc, errstr);
3528 tlsp->ocsp = OCSP_NOT_RESP;
3532 #ifdef EXIM_HAVE_TLS_RESUME
3533 tls_client_resume_prehandshake(state, tlsp, host, ob);
3536 #ifndef DISABLE_EVENT
3537 if (tb && tb->event_action)
3539 state->event_action = tb->event_action;
3540 gnutls_session_set_ptr(state->session, state);
3541 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
3545 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
3546 state->fd_in = cctx->sock;
3547 state->fd_out = cctx->sock;
3549 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
3550 /* There doesn't seem to be a built-in timeout on connection. */
3552 sigalrm_seen = FALSE;
3553 ALARM(ob->command_timeout);
3555 rc = gnutls_handshake(state->session);
3556 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3559 if (rc != GNUTLS_E_SUCCESS)
3563 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
3564 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
3567 tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
3571 DEBUG(D_tls) post_handshake_debug(state);
3575 if (!verify_certificate(state, errstr))
3577 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
3581 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3582 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3583 tlsp->ext_master_secret = TRUE;
3586 #ifndef DISABLE_OCSP
3591 gnutls_datum_t stapling;
3592 gnutls_ocsp_resp_t resp;
3593 gnutls_datum_t printed;
3597 # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
3598 (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
3600 (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
3603 if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0
3604 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
3605 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
3608 debug_printf("%.4096s", printed.data);
3609 gnutls_free(printed.data);
3612 (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
3614 (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
3617 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
3619 tlsp->ocsp = OCSP_FAILED;
3620 tls_error(US"certificate status check failed", NULL, state->host, errstr);
3626 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
3627 tlsp->ocsp = OCSP_VFIED;
3632 #ifdef EXIM_HAVE_TLS_RESUME
3633 tls_client_resume_posthandshake(state, tlsp, host);
3636 #ifdef EXIM_HAVE_ALPN
3637 if (ob->tls_alpn) /* We requested. See what was negotiated. */
3639 gnutls_datum_t p = {.size = 0};
3641 if (gnutls_alpn_get_selected_protocol(state->session, &p) == 0)
3642 { DEBUG(D_tls) debug_printf("ALPN negotiated: '%.*s'\n", (int)p.size, p.data); }
3643 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
3645 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
3646 tls_error(US"handshake", US"ALPN required but not negotiated", state->host, errstr);
3650 DEBUG(D_tls) debug_printf("No ALPN negotiated");
3654 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
3656 extract_exim_vars_from_tls_state(state);
3658 cctx->tls_ctx = state;
3667 ct_ctx client TLS context pointer, or NULL for the one global server context
3671 tls_shutdown_wr(void * ct_ctx)
3673 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3674 tls_support * tlsp = state->tlsp;
3676 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3678 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
3680 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
3681 gnutls_bye(state->session, GNUTLS_SHUT_WR);
3684 /*************************************************
3685 * Close down a TLS session *
3686 *************************************************/
3688 /* This is also called from within a delivery subprocess forked from the
3689 daemon, to shut down the TLS library, without actually doing a shutdown (which
3690 would tamper with the TLS session in the parent process).
3693 ct_ctx client context pointer, or NULL for the one global server context
3694 do_shutdown 0 no data-flush or TLS close-alert
3695 1 if TLS close-alert is to be sent,
3696 2 if also response to be waited for (2s timeout)
3702 tls_close(void * ct_ctx, int do_shutdown)
3704 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3705 tls_support * tlsp = state->tlsp;
3707 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3711 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3712 do_shutdown > 1 ? " (with response-wait)" : "");
3714 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
3717 gnutls_bye(state->session, do_shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
3721 if (!ct_ctx) /* server */
3723 receive_getc = smtp_getc;
3724 receive_getbuf = smtp_getbuf;
3725 receive_get_cache = smtp_get_cache;
3726 receive_ungetc = smtp_ungetc;
3727 receive_feof = smtp_feof;
3728 receive_ferror = smtp_ferror;
3729 receive_smtp_buffered = smtp_buffered;
3732 gnutls_deinit(state->session);
3733 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3734 state->lib_state = null_tls_preload;
3736 tlsp->active.sock = -1;
3737 tlsp->active.tls_ctx = NULL;
3738 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3739 tlsp->channelbinding = NULL;
3742 if (state->xfer_buffer) store_free(state->xfer_buffer);
3749 tls_refill(unsigned lim)
3751 exim_gnutls_state_st * state = &state_server;
3754 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, buffersize=%u)\n",
3755 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
3757 sigalrm_seen = FALSE;
3758 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3762 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
3763 MIN(ssl_xfer_buffer_size, lim));
3764 while (inbytes == GNUTLS_E_AGAIN);
3766 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3768 if (had_command_timeout) /* set by signal handler */
3769 smtp_command_timeout_exit(); /* does not return */
3770 if (had_command_sigterm)
3771 smtp_command_sigterm_exit();
3772 if (had_data_timeout)
3773 smtp_data_timeout_exit();
3774 if (had_data_sigint)
3775 smtp_data_sigint_exit();
3777 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3778 TLS session has been closed down, not that the socket itself has been closed
3779 down. Revert to non-TLS handling. */
3783 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3784 state->xfer_error = TRUE;
3788 else if (inbytes == 0)
3790 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3791 tls_close(NULL, TLS_NO_SHUTDOWN);
3795 /* Handle genuine errors */
3797 else if (inbytes < 0)
3799 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3800 record_io_error(state, (int) inbytes, US"recv", NULL);
3801 state->xfer_error = TRUE;
3804 #ifndef DISABLE_DKIM
3805 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3807 state->xfer_buffer_hwm = (int) inbytes;
3808 state->xfer_buffer_lwm = 0;
3812 /*************************************************
3813 * TLS version of getc *
3814 *************************************************/
3816 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3817 it refills the buffer via the GnuTLS reading function.
3818 Only used by the server-side TLS.
3820 This feeds DKIM and should be used for all message-body reads.
3822 Arguments: lim Maximum amount to read/buffer
3823 Returns: the next character or EOF
3827 tls_getc(unsigned lim)
3829 exim_gnutls_state_st * state = &state_server;
3831 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3832 if (!tls_refill(lim))
3833 return state->xfer_error ? EOF : smtp_getc(lim);
3835 /* Something in the buffer; return next uschar */
3837 return state->xfer_buffer[state->xfer_buffer_lwm++];
3841 tls_getbuf(unsigned * len)
3843 exim_gnutls_state_st * state = &state_server;
3847 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3848 if (!tls_refill(*len))
3850 if (!state->xfer_error) return smtp_getbuf(len);
3855 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3857 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3858 state->xfer_buffer_lwm += size;
3867 #ifndef DISABLE_DKIM
3868 exim_gnutls_state_st * state = &state_server;
3869 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3871 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3877 tls_could_read(void)
3879 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3880 || gnutls_record_check_pending(state_server.session) > 0;
3884 /*************************************************
3885 * Read bytes from TLS channel *
3886 *************************************************/
3888 /* This does not feed DKIM, so if the caller uses this for reading message body,
3889 then the caller must feed DKIM.
3892 ct_ctx client context pointer, or NULL for the one global server context
3896 Returns: the number of bytes read
3897 -1 after a failed read, including EOF
3901 tls_read(void * ct_ctx, uschar *buff, size_t len)
3903 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3909 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3911 debug_printf("*** PROBABLY A BUG *** " \
3912 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3913 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3916 debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, len=" SIZE_T_FMT ")\n",
3917 state->session, buff, len);
3921 inbytes = gnutls_record_recv(state->session, buff, len);
3922 while (inbytes == GNUTLS_E_AGAIN);
3924 if (inbytes > 0) return inbytes;
3927 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3931 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3932 record_io_error(state, (int)inbytes, US"recv", NULL);
3941 /*************************************************
3942 * Write bytes down TLS channel *
3943 *************************************************/
3947 ct_ctx client context pointer, or NULL for the one global server context
3950 more more data expected soon
3952 Calling with len zero and more unset will flush buffered writes. The buff
3953 argument can be null for that case.
3955 Returns: the number of bytes after a successful write,
3956 -1 after a failed write
3960 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3964 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3967 if (more && !state->corked)
3969 DEBUG(D_tls) debug_printf("gnutls_record_cork(session=%p)\n", state->session);
3970 gnutls_record_cork(state->session);
3971 state->corked = TRUE;
3975 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3976 buff, left, more ? ", more" : "");
3980 DEBUG(D_tls) debug_printf("gnutls_record_send(session=%p, buffer=%p, left=" SIZE_T_FMT ")\n",
3981 state->session, buff, left);
3985 outbytes = gnutls_record_send(state->session, buff, left);
3986 while (outbytes == GNUTLS_E_AGAIN);
3988 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
3992 #ifdef GNUTLS_E_PREMATURE_TERMINATION
3993 if ( outbytes == GNUTLS_E_PREMATURE_TERMINATION && errno == ECONNRESET
3994 && !ct_ctx && f.smtp_in_quit
3996 { /* Outlook, dammit */
3997 if (LOGGING(protocol_detail))
3998 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
3999 " SMTP response and TLS close\n", sender_host_address);
4001 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4002 " client reset TCP before TLS close\n", sender_host_address);
4007 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
4008 record_io_error(state, outbytes, US"send", NULL);
4014 record_io_error(state, 0, US"send", US"TLS channel closed on write");
4025 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
4031 if (!more && state->corked)
4033 DEBUG(D_tls) debug_printf("gnutls_record_uncork(session=%p)\n", state->session);
4035 /* We can't use GNUTLS_RECORD_WAIT here, as it retries on
4036 GNUTLS_E_AGAIN || GNUTLS_E_INTR, which would break our timeout set by alarm().
4037 The GNUTLS_E_AGAIN should not happen ever, as our sockets are blocking anyway.
4038 But who knows. (That all relies on the fact that GNUTLS_E_INTR and GNUTLS_E_AGAIN
4039 match the EINTR and EAGAIN errno values.) */
4040 outbytes = gnutls_record_uncork(state->session, 0);
4041 while (outbytes == GNUTLS_E_AGAIN);
4045 record_io_error(state, len, US"uncork", NULL);
4049 state->corked = FALSE;
4059 /*************************************************
4060 * Random number generation *
4061 *************************************************/
4063 /* Pseudo-random number generation. The result is not expected to be
4064 cryptographically strong but not so weak that someone will shoot themselves
4065 in the foot using it as a nonce in input in some email header scheme or
4066 whatever weirdness they'll twist this into. The result should handle fork()
4067 and avoid repeating sequences. OpenSSL handles that for us.
4071 Returns a random number in range [0, max-1]
4074 #ifdef HAVE_GNUTLS_RND
4076 vaguely_random_number(int max)
4080 uschar smallbuf[sizeof(r)];
4085 needed_len = sizeof(r);
4086 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4087 asked for a number less than 10. */
4089 for (r = max, i = 0; r; ++i)
4095 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
4098 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback\n");
4099 return vaguely_random_number_fallback(max);
4102 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4105 /* We don't particularly care about weighted results; if someone wants
4106 * smooth distribution and cares enough then they should submit a patch then. */
4109 #else /* HAVE_GNUTLS_RND */
4111 vaguely_random_number(int max)
4113 return vaguely_random_number_fallback(max);
4115 #endif /* HAVE_GNUTLS_RND */
4120 /*************************************************
4121 * Let tls_require_ciphers be checked at startup *
4122 *************************************************/
4124 /* The tls_require_ciphers option, if set, must be something which the
4127 Returns: NULL on success, or error message
4131 tls_validate_require_cipher(void)
4134 uschar *expciphers = NULL;
4135 gnutls_priority_t priority_cache;
4137 uschar * dummy_errstr;
4139 #ifdef GNUTLS_AUTO_GLOBAL_INIT
4140 # define validate_check_rc(Label) do { \
4141 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \
4142 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
4143 # define return_deinit(Label) do { return (Label); } while (0)
4145 # define validate_check_rc(Label) do { \
4146 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
4147 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
4148 # define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
4151 if (exim_gnutls_base_init_done)
4152 log_write(0, LOG_MAIN|LOG_PANIC,
4153 "already initialised GnuTLS, Exim developer bug");
4155 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
4156 if (!gnutls_allow_auto_pkcs11)
4158 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
4159 validate_check_rc(US"gnutls_pkcs11_init");
4162 #ifndef GNUTLS_AUTO_GLOBAL_INIT
4163 rc = gnutls_global_init();
4164 validate_check_rc(US"gnutls_global_init()");
4166 exim_gnutls_base_init_done = TRUE;
4168 if (!(tls_require_ciphers && *tls_require_ciphers))
4169 return_deinit(NULL);
4171 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4173 return_deinit(US"failed to expand tls_require_ciphers");
4175 if (!(expciphers && *expciphers))
4176 return_deinit(NULL);
4179 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4181 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
4182 validate_check_rc(string_sprintf(
4183 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
4184 expciphers, errpos - CS expciphers, errpos));
4186 #undef return_deinit
4187 #undef validate_check_rc
4188 #ifndef GNUTLS_AUTO_GLOBAL_INIT
4189 gnutls_global_deinit();
4198 /*************************************************
4199 * Report the library versions. *
4200 *************************************************/
4202 /* See a description in tls-openssl.c for an explanation of why this exists.
4204 Arguments: a FILE* to print the results to
4209 tls_version_report(FILE *f)
4211 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
4214 gnutls_check_version(NULL));
4217 #endif /*!MACRO_PREDEF*/
4220 /* End of tls-gnu.c */