1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Copyright (c) Phil Pennock 2012 */
11 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
12 one of the available supported implementations. This file is #included into
13 tls.c when USE_GNUTLS has been set.
15 The code herein is a revamp of GnuTLS integration using the current APIs; the
16 original tls-gnu.c was based on a patch which was contributed by Nikos
17 Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as
20 APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
21 which is not widely deployed by OS vendors. Will note issues below, which may
22 assist in updating the code in the future. Another sources of hints is
23 mod_gnutls for Apache (SNI callback registration and handling).
25 Keeping client and server variables more split than before and is currently
26 the norm, in anticipation of TLS in ACL callouts.
28 I wanted to switch to gnutls_certificate_set_verify_function() so that
29 certificate rejection could happen during handshake where it belongs, rather
30 than being dropped afterwards, but that was introduced in 2.10.0 and Debian
31 (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
33 (I wasn't looking for libraries quite that old, when updating to get rid of
34 compiler warnings of deprecated APIs. If it turns out that a lot of the rest
35 require current GnuTLS, then we'll drop support for the ancient libraries).
38 #include <gnutls/gnutls.h>
39 /* needed for cert checks in verification and DN extraction: */
40 #include <gnutls/x509.h>
41 /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
42 #include <gnutls/crypto.h>
44 /* needed to disable PKCS11 autoload unless requested */
45 #if GNUTLS_VERSION_NUMBER >= 0x020c00
46 # include <gnutls/pkcs11.h>
47 # define SUPPORT_PARAM_TO_PK_BITS
49 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
50 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
53 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
54 # warning "GnuTLS library version too old; tls:cert event unsupported"
55 # define DISABLE_EVENT
57 #if GNUTLS_VERSION_NUMBER >= 0x030000
58 # define SUPPORT_SELFSIGN /* Uncertain what version is first usable but 2.12.23 is not */
60 #if GNUTLS_VERSION_NUMBER >= 0x030306
61 # define SUPPORT_CA_DIR
63 # undef SUPPORT_CA_DIR
65 #if GNUTLS_VERSION_NUMBER >= 0x030014
66 # define SUPPORT_SYSDEFAULT_CABUNDLE
68 #if GNUTLS_VERSION_NUMBER >= 0x030104
69 # define GNUTLS_CERT_VFY_STATUS_PRINT
71 #if GNUTLS_VERSION_NUMBER >= 0x030109
74 #if GNUTLS_VERSION_NUMBER >= 0x03010a
75 # define SUPPORT_GNUTLS_SESS_DESC
77 #if GNUTLS_VERSION_NUMBER >= 0x030300
78 # define GNUTLS_AUTO_GLOBAL_INIT
79 # define GNUTLS_AUTO_PKCS11_MANUAL
81 #if (GNUTLS_VERSION_NUMBER >= 0x030404) \
82 || (GNUTLS_VERSION_NUMBER >= 0x030311) && (GNUTLS_VERSION_NUMBER & 0xffff00 == 0x030300)
84 # define EXIM_HAVE_OCSP
87 #if GNUTLS_VERSION_NUMBER >= 0x030500
88 # define SUPPORT_GNUTLS_KEYLOG
90 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
91 # define SUPPORT_SRV_OCSP_STACK
93 #if GNUTLS_VERSION_NUMBER >= 0x030600
94 # define GNUTLS_AUTO_DHPARAMS
96 #if GNUTLS_VERSION_NUMBER >= 0x030603
97 # define EXIM_HAVE_TLS1_3
98 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
99 # define GNUTLS_OCSP_STATUS_REQUEST_GET2
103 # if GNUTLS_VERSION_NUMBER >= 0x030000
104 # define DANESSL_USAGE_DANE_TA 2
105 # define DANESSL_USAGE_DANE_EE 3
107 # error GnuTLS version too early for DANE
109 # if GNUTLS_VERSION_NUMBER < 0x999999
110 # define GNUTLS_BROKEN_DANE_VALIDATION
114 #ifndef DISABLE_TLS_RESUME
115 # if GNUTLS_VERSION_NUMBER >= 0x030603
116 # define EXIM_HAVE_TLS_RESUME
118 # warning "GnuTLS library version too old; resumption unsupported"
122 #if GNUTLS_VERSION_NUMBER >= 0x030200
123 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
124 # define EXIM_HAVE_ALPN
129 # include <gnutls/ocsp.h>
132 # include <gnutls/dane.h>
135 #include "tls-cipher-stdname.c"
142 # ifndef DISABLE_TLS_RESUME
143 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
145 # ifdef EXIM_HAVE_TLS1_3
146 builtin_macro_create(US"_HAVE_TLS1_3");
148 # ifdef EXIM_HAVE_OCSP
149 builtin_macro_create(US"_HAVE_TLS_OCSP");
151 # ifdef SUPPORT_SRV_OCSP_STACK
152 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
154 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
155 builtin_macro_create(US"_HAVE_TLS_CA_CACHE");
157 # ifdef EXIM_HAVE_ALPN
158 builtin_macro_create(US"_HAVE_TLS_ALPN");
167 gnutls_global_set_audit_log_function()
170 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
173 /* Local static variables for GnuTLS */
175 /* Values for verify_requirement */
177 enum peer_verify_requirement
178 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
180 /* This holds most state for server or client; with this, we can set up an
181 outbound TLS-enabled connection in an ACL callout, while not stomping all
182 over the TLS variables available for expansion.
184 Some of these correspond to variables in globals.c; those variables will
185 be set to point to content in one of these instances, as appropriate for
186 the stage of the process lifetime.
188 Not handled here: global tlsp->tls_channelbinding.
191 typedef struct exim_gnutls_state {
192 gnutls_session_t session;
194 exim_tlslib_state lib_state;
195 #define x509_cred libdata0
196 #define pri_cache libdata1
198 enum peer_verify_requirement verify_requirement;
202 BOOL peer_cert_verified:1;
203 BOOL peer_dane_verified:1;
204 BOOL trigger_sni_changes:1;
205 BOOL have_set_peerdn:1;
206 BOOL xfer_eof:1; /*XXX never gets set! */
212 const struct host_item *host; /* NULL if server */
213 gnutls_x509_crt_t peercert;
216 uschar *received_sni;
218 const uschar *tls_certificate;
219 const uschar *tls_privatekey;
220 const uschar *tls_sni; /* client send only, not received */
221 const uschar *tls_verify_certificates;
222 const uschar *tls_crl;
223 const uschar *tls_require_ciphers;
225 uschar *exp_tls_certificate;
226 uschar *exp_tls_privatekey;
227 uschar *exp_tls_verify_certificates;
229 uschar *exp_tls_require_ciphers;
230 const uschar *exp_tls_verify_cert_hostnames;
231 #ifndef DISABLE_EVENT
232 uschar *event_action;
235 char * const * dane_data;
236 const int * dane_data_len;
239 tls_support *tlsp; /* set in tls_init() */
244 } exim_gnutls_state_st;
246 static const exim_gnutls_state_st exim_gnutls_state_init = {
247 /* all elements not explicitly intialised here get 0/NULL/FALSE */
252 /* Not only do we have our own APIs which don't pass around state, assuming
253 it's held in globals, GnuTLS doesn't appear to let us register callback data
254 for callbacks, or as part of the session, so we have to keep a "this is the
255 context we're currently dealing with" pointer and rely upon being
256 single-threaded to keep from processing data on an inbound TLS connection while
257 talking to another TLS connection for an outbound check. This does mean that
258 there's no way for heart-beats to be responded to, for the duration of the
260 XXX But see gnutls_session_get_ptr()
263 static exim_gnutls_state_st state_server = {
264 /* all elements not explicitly intialised here get 0/NULL/FALSE */
269 #ifndef GNUTLS_AUTO_DHPARAMS
270 /* dh_params are initialised once within the lifetime of a process using TLS;
271 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
272 don't want to repeat this. */
274 static gnutls_dh_params_t dh_server_params = NULL;
277 static int ssl_session_timeout = 7200; /* Two hours */
279 static const uschar * const exim_default_gnutls_priority = US"NORMAL";
281 /* Guard library core initialisation */
283 static BOOL exim_gnutls_base_init_done = FALSE;
286 static BOOL gnutls_buggy_ocsp = FALSE;
287 static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
290 #ifdef EXIM_HAVE_ALPN
291 static int server_seen_alpn = -1; /* count of names */
293 #ifdef EXIM_HAVE_TLS_RESUME
294 static gnutls_datum_t server_sessticket_key;
298 /* ------------------------------------------------------------------------ */
301 #define MAX_HOST_LEN 255
303 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
304 the library logging; a value less than 0 disables the calls to set up logging
305 callbacks. GNuTLS also looks for an environment variable - except not for
306 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
307 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
308 but the env var must be added to /etc/sudoers too. */
309 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
310 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
313 #ifndef EXIM_CLIENT_DH_MIN_BITS
314 # define EXIM_CLIENT_DH_MIN_BITS 1024
317 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
318 can ask for a bit-strength. Without that, we stick to the constant we had
320 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
321 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
324 #define Expand_check_tlsvar(Varname, errstr) \
325 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
327 #if GNUTLS_VERSION_NUMBER >= 0x020c00
328 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
329 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
330 # define HAVE_GNUTLS_RND
331 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
332 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
333 * isn't available sometimes, so this needs to become a conditional
334 * compilation; the sanest way to deal with this being a problem on
335 * older OSes is to block it in the Local/Makefile with this compiler
337 # ifndef AVOID_GNUTLS_PKCS11
338 # define HAVE_GNUTLS_PKCS11
339 # endif /* AVOID_GNUTLS_PKCS11 */
345 /* ------------------------------------------------------------------------ */
346 /* Callback declarations */
348 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
349 static void exim_gnutls_logger_cb(int level, const char *message);
352 static int exim_sni_handling_cb(gnutls_session_t session);
354 #ifdef EXIM_HAVE_TLS_RESUME
356 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
357 unsigned incoming, const gnutls_datum_t * msg);
361 /*************************************************
363 *************************************************/
365 /* Called from lots of places when errors occur before actually starting to do
366 the TLS handshake, that is, while the session is still in clear. Always returns
367 DEFER for a server and FAIL for a client so that most calls can use "return
368 tls_error(...)" to do this processing and then give an appropriate return. A
369 single function is used for both server and client, because it is called from
370 some shared functions.
373 prefix text to include in the logged error
374 msg additional error string (may be NULL)
375 usually obtained from gnutls_strerror()
376 host NULL if setting up a server;
377 the connected host if setting up a client
378 errstr pointer to returned error string
380 Returns: OK/DEFER/FAIL
384 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
388 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
389 return host ? FAIL : DEFER;
394 tls_error_gnu(exim_gnutls_state_st * state, const uschar *prefix, int err,
397 return tls_error(prefix,
398 state && err == GNUTLS_E_FATAL_ALERT_RECEIVED
399 ? US gnutls_alert_get_name(gnutls_alert_get(state->session))
400 : US gnutls_strerror(err),
401 state ? state->host : NULL,
406 tls_error_sys(const uschar *prefix, int err, const host_item *host,
409 return tls_error(prefix, US strerror(err), host, errstr);
413 /* ------------------------------------------------------------------------ */
419 tls_is_buggy_ocsp(void)
422 uschar maj, mid, mic;
424 s = CUS gnutls_check_version(NULL);
428 while (*s && *s != '.') s++;
436 while (*s && *s != '.') s++;
438 return mic <= (mid == 3 ? 16 : 3);
448 tls_g_init(uschar ** errstr)
451 DEBUG(D_tls) debug_printf("GnuTLS global init required\n");
453 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
454 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
455 which loads modules from a config file, which sounds good and may be wanted
456 by some sysadmin, but also means in common configurations that GNOME keyring
457 environment variables are used and so breaks for users calling mailq.
458 To prevent this, we init PKCS11 first, which is the documented approach. */
460 if (!gnutls_allow_auto_pkcs11)
461 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
462 return tls_error_gnu(NULL, US"gnutls_pkcs11_init", rc, errstr);
465 #ifndef GNUTLS_AUTO_GLOBAL_INIT
466 if ((rc = gnutls_global_init()))
467 return tls_error_gnu(NULL, US"gnutls_global_init", rc, errstr);
470 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
473 gnutls_global_set_log_function(exim_gnutls_logger_cb);
474 /* arbitrarily chosen level; bump up to 9 for more */
475 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
480 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
481 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
484 exim_gnutls_base_init_done = TRUE;
490 /* Daemon-call before each connection. Nothing to do for GnuTLS. */
493 tls_per_lib_daemon_tick(void)
497 /* Daemon one-time initialisation */
500 tls_per_lib_daemon_init(void)
502 uschar * dummy_errstr;
503 static BOOL once = FALSE;
505 if (!exim_gnutls_base_init_done)
506 tls_g_init(&dummy_errstr);
512 #ifdef EXIM_HAVE_TLS_RESUME
513 /* We are dependent on the GnuTLS implementation of the Session Ticket
514 encryption; both the strength and the key rotation period. We hope that
515 the strength at least matches that of the ciphersuite (but GnuTLS does not
518 gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
519 if (f.running_in_test_harness) ssl_session_timeout = 6;
522 tls_daemon_creds_reload();
526 /* ------------------------------------------------------------------------ */
528 /*************************************************
529 * Deal with logging errors during I/O *
530 *************************************************/
532 /* We have to get the identity of the peer from saved data.
535 state the current GnuTLS exim state container
536 rc the GnuTLS error code, or 0 if it's a local error
537 when text identifying read or write
538 text local error text when rc is 0
544 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
549 msg = rc == GNUTLS_E_FATAL_ALERT_RECEIVED
550 ? string_sprintf("A TLS fatal alert has been received: %s",
551 US gnutls_alert_get_name(gnutls_alert_get(state->session)))
552 #ifdef GNUTLS_E_PREMATURE_TERMINATION
553 : rc == GNUTLS_E_PREMATURE_TERMINATION && errno
554 ? string_sprintf("%s: syscall: %s", US gnutls_strerror(rc), strerror(errno))
556 : US gnutls_strerror(rc);
558 (void) tls_error(when, msg, state->host, &errstr);
561 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
562 state->host->name, state->host->address, errstr);
565 uschar * conn_info = smtp_get_connection_info();
566 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
567 /* I'd like to get separated H= here, but too hard for now */
568 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
575 /*************************************************
576 * Set various Exim expansion vars *
577 *************************************************/
579 #define exim_gnutls_cert_err(Label) \
582 if (rc != GNUTLS_E_SUCCESS) \
584 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
585 (Label), gnutls_strerror(rc)); \
591 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
595 rc = gnutls_x509_crt_init(crtp);
596 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
598 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
599 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
604 #undef exim_gnutls_cert_err
607 /* We set various Exim global variables from the state, once a session has
608 been established. With TLS callouts, may need to change this to stack
609 variables, or just re-call it with the server state after client callout
612 Make sure anything set here is unset in tls_getc().
616 tls_bits strength indicator
617 tls_certificate_verified bool indicator
618 tls_channelbinding for some SASL mechanisms
621 tls_peercert pointer to library internal
623 tls_sni a (UTF-8) string
624 tls_ourcert pointer to library internal
627 state the relevant exim_gnutls_state_st *
631 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
633 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
636 gnutls_datum_t channel;
638 tls_support * tlsp = state->tlsp;
640 tlsp->active.sock = state->fd_out;
641 tlsp->active.tls_ctx = state;
643 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
645 tlsp->certificate_verified = state->peer_cert_verified;
647 tlsp->dane_verified = state->peer_dane_verified;
650 /* note that tls_channelbinding is not saved to the spool file, since it's
651 only available for use for authenticators while this TLS session is running. */
653 tlsp->channelbinding = NULL;
654 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
657 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
658 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
661 /* Declare the taintedness of the binding info. On server, untainted; on
662 client, tainted - being the Finish msg from the server. */
664 old_pool = store_pool;
665 store_pool = POOL_PERM;
666 tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
668 store_pool = old_pool;
669 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
673 /* peercert is set in peer_status() */
674 tlsp->peerdn = state->peerdn;
676 /* do not corrupt sni sent by client; record sni rxd by server */
678 tlsp->sni = state->received_sni;
680 /* record our certificate */
682 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
683 gnutls_x509_crt_t crt;
685 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
692 #ifndef GNUTLS_AUTO_DHPARAMS
693 /*************************************************
694 * Setup up DH parameters *
695 *************************************************/
697 /* Generating the D-H parameters may take a long time. They only need to
698 be re-generated every so often, depending on security policy. What we do is to
699 keep these parameters in a file in the spool directory. If the file does not
700 exist, we generate them. This means that it is easy to cause a regeneration.
702 The new file is written as a temporary file and renamed, so that an incomplete
703 file is never present. If two processes both compute some new parameters, you
704 waste a bit of effort, but it doesn't seem worth messing around with locking to
707 Returns: OK/DEFER/FAIL
711 init_server_dh(uschar ** errstr)
714 unsigned int dh_bits;
715 gnutls_datum_t m = {.data = NULL, .size = 0};
716 uschar filename_buf[PATH_MAX];
717 uschar *filename = NULL;
719 uschar *exp_tls_dhparam;
720 BOOL use_file_in_spool = FALSE;
721 host_item *host = NULL; /* dummy for macros */
723 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
725 if ((rc = gnutls_dh_params_init(&dh_server_params)))
726 return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
728 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
731 if (!exp_tls_dhparam)
733 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
734 m.data = US std_dh_prime_default();
735 m.size = Ustrlen(m.data);
737 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
738 use_file_in_spool = TRUE;
739 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
741 DEBUG(D_tls) debug_printf("Requested no DH parameters\n");
744 else if (exp_tls_dhparam[0] != '/')
746 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
747 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
748 m.size = Ustrlen(m.data);
751 filename = exp_tls_dhparam;
755 if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
756 return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
757 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
761 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
762 /* If you change this constant, also change dh_param_fn_ext so that we can use a
763 different filename and ensure we have sufficient bits. */
765 if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
766 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
768 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits\n",
771 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
773 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits\n",
777 /* Some clients have hard-coded limits. */
778 if (dh_bits > tls_dh_max_bits)
781 debug_printf("tls_dh_max_bits clamping override, using %d bits instead\n",
783 dh_bits = tls_dh_max_bits;
786 if (use_file_in_spool)
788 if (!string_format(filename_buf, sizeof(filename_buf),
789 "%s/gnutls-params-%d", spool_directory, dh_bits))
790 return tls_error(US"overlong filename", NULL, NULL, errstr);
791 filename = filename_buf;
794 /* Open the cache file for reading and if successful, read it and set up the
797 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
803 if (fstat(fd, &statbuf) < 0) /* EIO */
807 return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
809 if (!S_ISREG(statbuf.st_mode))
812 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
814 if (!(fp = fdopen(fd, "rb")))
818 return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
819 saved_errno, NULL, errstr);
822 m.size = statbuf.st_size;
823 if (!(m.data = store_malloc(m.size)))
826 return tls_error_sys(US"malloc failed", errno, NULL, errstr);
828 if (!(sz = fread(m.data, m.size, 1, fp)))
833 return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
837 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
840 return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
841 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
844 /* If the file does not exist, fall through to compute new data and cache it.
845 If there was any other opening error, it is serious. */
847 else if (errno == ENOENT)
851 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
854 return tls_error(string_open_failed("\"%s\" for reading", filename),
857 /* If ret < 0, either the cache file does not exist, or the data it contains
858 is not useful. One particular case of this is when upgrading from an older
859 release of Exim in which the data was stored in a different format. We don't
860 try to be clever and support both formats; we just regenerate new data in this
866 unsigned int dh_bits_gen = dh_bits;
868 if ((PATH_MAX - Ustrlen(filename)) < 10)
869 return tls_error(US"Filename too long to generate replacement",
870 filename, NULL, errstr);
872 temp_fn = string_copy(US"exim-dh.XXXXXXX");
873 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
874 return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
875 (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
877 /* GnuTLS overshoots! If we ask for 2236, we might get 2237 or more. But
878 there's no way to ask GnuTLS how many bits there really are. We can ask
879 how many bits were used in a TLS session, but that's it! The prime itself
880 is hidden behind too much abstraction. So we ask for less, and proceed on
881 a wing and a prayer. First attempt, subtracted 3 for 2233 and got 2240. */
883 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
885 dh_bits_gen = dh_bits - 10;
887 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
892 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
894 if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
895 return tls_error_gnu(NULL, US"gnutls_dh_params_generate2", rc, errstr);
897 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
898 and I confirmed that a NULL call to get the size first is how the GnuTLS
899 sample apps handle this. */
903 if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
904 GNUTLS_X509_FMT_PEM, m.data, &sz))
905 && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
906 return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3(NULL) sizing",
909 if (!(m.data = store_malloc(m.size)))
910 return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
912 /* this will return a size 1 less than the allocation size above */
913 if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
917 return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3() real", rc, errstr);
919 m.size = sz; /* shrink by 1, probably */
921 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
924 return tls_error_sys(US"TLS cache write D-H params failed",
925 errno, NULL, errstr);
928 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
929 return tls_error_sys(US"TLS cache write D-H params final newline failed",
930 errno, NULL, errstr);
932 if ((rc = close(fd)))
933 return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
935 if (Urename(temp_fn, filename) < 0)
936 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
937 temp_fn, filename), errno, NULL, errstr);
939 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
942 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
950 /* Create and install a selfsigned certificate, for use in server mode. */
953 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
955 gnutls_x509_crt_t cert = NULL;
957 gnutls_x509_privkey_t pkey = NULL;
958 const uschar * where;
961 #ifndef SUPPORT_SELFSIGN
962 where = US"library too old";
963 rc = GNUTLS_E_NO_CERTIFICATE_FOUND;
967 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
968 where = US"initialising pkey";
969 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
971 where = US"initialising cert";
972 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
974 where = US"generating pkey"; /* Hangs on 2.12.23 */
975 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
976 #ifdef SUPPORT_PARAM_TO_PK_BITS
977 # ifndef GNUTLS_SEC_PARAM_MEDIUM
978 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
980 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
987 where = US"configuring cert";
989 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
990 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
991 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
992 || (rc = gnutls_x509_crt_set_expiration_time(cert, (long)2 * 60 * 60)) /* 2 hour */
993 || (rc = gnutls_x509_crt_set_key(cert, pkey))
995 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
996 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
997 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
998 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
999 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
1000 GNUTLS_OID_X520_COMMON_NAME, 0,
1001 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
1005 where = US"signing cert";
1006 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
1008 where = US"installing selfsign cert";
1010 if ((rc = gnutls_certificate_set_x509_key(state->lib_state.x509_cred,
1017 if (cert) gnutls_x509_crt_deinit(cert);
1018 if (pkey) gnutls_x509_privkey_deinit(pkey);
1022 rc = tls_error_gnu(state, where, rc, errstr);
1029 /* Add certificate and key, from files.
1032 Zero or negative: good. Negate value for certificate index if < 0.
1033 Greater than zero: FAIL or DEFER code.
1037 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
1038 const uschar * certfile, const uschar * keyfile, uschar ** errstr)
1040 int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
1041 CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
1043 return tls_error_gnu(state,
1044 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
1050 #if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1051 /* Load an OCSP proof from file for sending by the server. Called
1052 on getting a status-request handshake message, for earlier versions
1056 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
1057 gnutls_datum_t * ocsp_response)
1060 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
1062 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
1064 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
1066 tls_in.ocsp = OCSP_NOT_RESP;
1067 return GNUTLS_E_NO_CERTIFICATE_STATUS;
1070 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1076 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1077 /* Make a note that we saw a status-request */
1079 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
1080 const uschar * data, unsigned size)
1082 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1085 case 5: /* Status Request */
1086 DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
1087 tls_in.ocsp = OCSP_NOT_RESP;
1089 #ifdef EXIM_HAVE_ALPN
1090 case 16: /* Application Layer Protocol Notification */
1091 /* The format of "data" here doesn't seem to be documented, but appears
1092 to be a 2-byte field with a (redundant, given the "size" arg) total length
1093 then a sequence of one-byte size then string (not nul-term) names. The
1094 latter is as described in OpenSSL documentation. */
1096 DEBUG(D_tls) debug_printf("Seen ALPN extension from client (s=%u):", size);
1097 for (const uschar * s = data+2; s-data < size-1; s += *s + 1)
1100 DEBUG(D_tls) debug_printf(" '%.*s'", (int)*s, s+1);
1102 DEBUG(D_tls) debug_printf("\n");
1103 if (server_seen_alpn > 1)
1105 DEBUG(D_tls) debug_printf("TLS: too many ALPNs presented in handshake\n");
1106 return GNUTLS_E_NO_APPLICATION_PROTOCOL;
1114 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
1116 tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
1117 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1119 /* Call fn for each extension seen. 3.6.3 onwards */
1120 return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
1121 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
1125 # ifdef notdef_crashes
1126 /* Make a note that we saw a status-response */
1128 tls_server_servercerts_ext(void * ctx, unsigned tls_id,
1129 const unsigned char *data, unsigned size)
1131 /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
1132 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
1133 if (FALSE && tls_id == 5) /* status_request */
1135 DEBUG(D_tls) debug_printf("Seen status_request extension\n");
1136 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1137 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1143 /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
1145 tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
1146 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1148 /* Call fn for each extension seen. 3.6.3 onwards */
1149 # ifdef notdef_crashes
1151 return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
1154 #endif /*SUPPORT_GNUTLS_EXT_RAW_PARSE*/
1156 /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
1157 "Handshake Protocol: Certificate" record.
1158 So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
1160 This is different to tls1.2 - where it is a separate record (wireshark term) / handshake message (gnutls term).
1163 #if defined(EXIM_HAVE_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1164 /* Callback for certificate-status, on server. We sent stapled OCSP. */
1166 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
1167 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
1169 DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
1170 # ifdef SUPPORT_SRV_OCSP_STACK
1171 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
1172 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
1174 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1179 /* Callback for handshake messages, on server */
1181 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
1182 unsigned incoming, const gnutls_datum_t * msg)
1184 /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
1187 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1188 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
1189 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
1190 case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
1191 return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
1193 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
1194 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
1195 # ifdef EXIM_HAVE_TLS_RESUME
1196 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
1197 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
1206 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1208 tls_server_testharness_ocsp_fiddle(void)
1210 extern char ** environ;
1211 if (environ) for (uschar ** p = USS environ; *p; p++)
1212 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1214 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
1215 exim_testharness_disable_ocsp_validity_check = TRUE;
1220 /**************************************************
1221 * One-time init credentials for server and client *
1222 **************************************************/
1225 creds_basic_init(gnutls_certificate_credentials_t x509_cred, BOOL server)
1227 #ifdef SUPPORT_SRV_OCSP_STACK
1228 gnutls_certificate_set_flags(x509_cred, GNUTLS_CERTIFICATE_API_V2);
1230 # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1231 if (server && tls_ocsp_file)
1233 if (f.running_in_test_harness)
1234 tls_server_testharness_ocsp_fiddle();
1236 if (exim_testharness_disable_ocsp_validity_check)
1237 gnutls_certificate_set_flags(x509_cred,
1238 GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
1243 debug_printf("TLS: basic cred init, %s\n", server ? "server" : "client");
1247 creds_load_server_certs(exim_gnutls_state_st * state, const uschar * cert,
1248 const uschar * pkey, const uschar * ocsp, uschar ** errstr)
1250 const uschar * clist = cert;
1251 const uschar * klist = pkey;
1252 const uschar * olist;
1253 int csep = 0, ksep = 0, osep = 0, cnt = 0, rc;
1254 uschar * cfile, * kfile, * ofile;
1255 #ifndef DISABLE_OCSP
1256 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1257 gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
1260 if (!expand_check(ocsp, US"tls_ocsp_file", &ofile, errstr))
1265 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1267 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1268 return tls_error(US"cert/key setup: out of keys", NULL, NULL, errstr);
1269 else if ((rc = tls_add_certfile(state, NULL, cfile, kfile, errstr)) > 0)
1273 int gnutls_cert_index = -rc;
1274 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
1275 gnutls_cert_index, cfile);
1277 #ifndef DISABLE_OCSP
1280 /* Set the OCSP stapling server info */
1281 if (gnutls_buggy_ocsp)
1284 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1286 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1288 DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n",
1289 gnutls_cert_index, ofile);
1290 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1291 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1293 ocsp_fmt = GNUTLS_X509_FMT_PEM;
1296 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1298 ocsp_fmt = GNUTLS_X509_FMT_DER;
1302 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1303 state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
1305 return tls_error_gnu(state,
1306 US"gnutls_certificate_set_ocsp_status_request_file2",
1309 debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
1311 /* Arrange callbacks for OCSP request observability */
1314 gnutls_handshake_set_hook_function(state->session,
1315 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1317 state->lib_state.ocsp_hook = TRUE;
1321 # if defined(SUPPORT_SRV_OCSP_STACK)
1322 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1323 state->lib_state.x509_cred, gnutls_cert_index,
1324 server_ocsp_stapling_cb, ofile)))
1325 return tls_error_gnu(state,
1326 US"gnutls_certificate_set_ocsp_status_request_function2",
1334 debug_printf("oops; multiple OCSP files not supported\n");
1337 gnutls_certificate_set_ocsp_status_request_function(
1338 state->lib_state.x509_cred, server_ocsp_stapling_cb, ofile);
1340 # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
1343 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1345 #endif /* DISABLE_OCSP */
1351 creds_load_client_certs(exim_gnutls_state_st * state, const host_item * host,
1352 const uschar * cert, const uschar * pkey, uschar ** errstr)
1354 int rc = tls_add_certfile(state, host, cert, pkey, errstr);
1355 if (rc > 0) return rc;
1356 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1361 creds_load_cabundle(exim_gnutls_state_st * state, const uschar * bundle,
1362 const host_item * host, uschar ** errstr)
1365 struct stat statbuf;
1367 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1368 if (Ustrcmp(bundle, "system") == 0 || Ustrncmp(bundle, "system,", 7) == 0)
1369 cert_count = gnutls_certificate_set_x509_system_trust(state->lib_state.x509_cred);
1373 if (Ustat(bundle, &statbuf) < 0)
1375 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' "
1376 "(tls_verify_certificates): %s", bundle, strerror(errno));
1380 #ifndef SUPPORT_CA_DIR
1381 /* The test suite passes in /dev/null; we could check for that path explicitly,
1382 but who knows if someone has some weird FIFO which always dumps some certs, or
1383 other weirdness. The thing we really want to check is that it's not a
1384 directory, since while OpenSSL supports that, GnuTLS does not.
1385 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1386 if (S_ISDIR(statbuf.st_mode))
1388 log_write(0, LOG_MAIN|LOG_PANIC,
1389 "tls_verify_certificates \"%s\" is a directory", bundle);
1394 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1395 bundle, statbuf.st_size);
1397 if (statbuf.st_size == 0)
1400 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1406 #ifdef SUPPORT_CA_DIR
1407 (statbuf.st_mode & S_IFMT) == S_IFDIR
1409 gnutls_certificate_set_x509_trust_dir(state->lib_state.x509_cred,
1410 CS bundle, GNUTLS_X509_FMT_PEM)
1413 gnutls_certificate_set_x509_trust_file(state->lib_state.x509_cred,
1414 CS bundle, GNUTLS_X509_FMT_PEM);
1416 #ifdef SUPPORT_CA_DIR
1417 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1418 when using the directory-of-certs config model. */
1420 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1422 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1424 state->lib_state.ca_rdn_emulate = TRUE;
1429 return tls_error_gnu(state, US"setting certificate trust", cert_count, errstr);
1431 debug_printf("Added %d certificate authorities\n", cert_count);
1438 creds_load_crl(exim_gnutls_state_st * state, const uschar * crl, uschar ** errstr)
1441 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
1442 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
1443 CS crl, GNUTLS_X509_FMT_PEM)) < 0)
1444 return tls_error_gnu(state, US"gnutls_certificate_set_x509_crl_file",
1445 cert_count, errstr);
1447 DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
1453 creds_load_pristring(exim_gnutls_state_st * state, const uschar * p,
1454 const char ** errpos)
1458 p = exim_default_gnutls_priority;
1460 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1462 return gnutls_priority_init( (gnutls_priority_t *) &state->lib_state.pri_cache,
1467 tls_server_creds_init(void)
1469 uschar * dummy_errstr;
1470 unsigned lifetime = 0;
1472 state_server.lib_state = null_tls_preload;
1473 if (gnutls_certificate_allocate_credentials(
1474 (gnutls_certificate_credentials_t *) &state_server.lib_state.x509_cred))
1476 state_server.lib_state.x509_cred = NULL;
1479 creds_basic_init(state_server.lib_state.x509_cred, TRUE);
1481 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1482 /* If tls_certificate has any $ indicating expansions, it is not good.
1483 If tls_privatekey is set but has $, not good. Likewise for tls_ocsp_file.
1484 If all good (and tls_certificate set), load the cert(s). */
1486 if ( opt_set_and_noexpand(tls_certificate)
1487 # ifndef DISABLE_OCSP
1488 && opt_unset_or_noexpand(tls_ocsp_file)
1490 && opt_unset_or_noexpand(tls_privatekey))
1492 /* Set watches on the filenames. The implementation does de-duplication
1493 so we can just blindly do them all.
1496 if ( tls_set_watch(tls_certificate, TRUE)
1497 # ifndef DISABLE_OCSP
1498 && tls_set_watch(tls_ocsp_file, TRUE)
1500 && tls_set_watch(tls_privatekey, TRUE))
1502 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1503 if (creds_load_server_certs(&state_server, tls_certificate,
1504 tls_privatekey && *tls_privatekey ? tls_privatekey : tls_certificate,
1505 # ifdef DISABLE_OCSP
1510 &dummy_errstr) == 0)
1511 state_server.lib_state.conn_certs = TRUE;
1514 else if ( !tls_certificate && !tls_privatekey
1515 # ifndef DISABLE_OCSP
1519 { /* Generate & preload a selfsigned cert. No files to watch. */
1520 if ((tls_install_selfsign(&state_server, &dummy_errstr)) == OK)
1522 state_server.lib_state.conn_certs = TRUE;
1523 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1527 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1529 /* If tls_verify_certificates is non-empty and has no $, load CAs */
1531 if (opt_set_and_noexpand(tls_verify_certificates))
1533 if (tls_set_watch(tls_verify_certificates, FALSE))
1535 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1536 if (creds_load_cabundle(&state_server, tls_verify_certificates,
1537 NULL, &dummy_errstr) != OK)
1539 state_server.lib_state.cabundle = TRUE;
1541 /* If CAs loaded and tls_crl is non-empty and has no $, load it */
1543 if (opt_set_and_noexpand(tls_crl))
1545 if (tls_set_watch(tls_crl, FALSE))
1547 DEBUG(D_tls) debug_printf("TLS: preloading CRL for server\n");
1548 if (creds_load_crl(&state_server, tls_crl, &dummy_errstr) != OK)
1550 state_server.lib_state.crl = TRUE;
1554 DEBUG(D_tls) debug_printf("TLS: not preloading CRL for server\n");
1558 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1559 #endif /* EXIM_HAVE_INOTIFY */
1561 /* If tls_require_ciphers is non-empty and has no $, load the
1562 ciphers priority cache. If unset, load with the default.
1563 (server-only as the client one depends on non/DANE) */
1565 if (!tls_require_ciphers || opt_set_and_noexpand(tls_require_ciphers))
1567 const char * dummy_errpos;
1568 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server: %s\n",
1569 tls_require_ciphers);
1570 if ( creds_load_pristring(&state_server, tls_require_ciphers, &dummy_errpos)
1572 state_server.lib_state.pri_string = TRUE;
1575 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1580 /* Preload whatever creds are static, onto a transport. The client can then
1581 just copy the pointer as it starts up. */
1584 tls_client_creds_init(transport_instance * t, BOOL watch)
1586 smtp_transport_options_block * ob = t->options_block;
1587 exim_gnutls_state_st tpt_dummy_state;
1588 host_item * dummy_host = (host_item *)1;
1589 uschar * dummy_errstr;
1591 if ( !exim_gnutls_base_init_done
1592 && tls_g_init(&dummy_errstr) != OK)
1595 ob->tls_preload = null_tls_preload;
1596 if (gnutls_certificate_allocate_credentials(
1597 (struct gnutls_certificate_credentials_st **)&ob->tls_preload.x509_cred))
1599 ob->tls_preload.x509_cred = NULL;
1602 creds_basic_init(ob->tls_preload.x509_cred, FALSE);
1604 tpt_dummy_state.session = NULL;
1605 tpt_dummy_state.lib_state = ob->tls_preload;
1607 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1608 if ( opt_set_and_noexpand(ob->tls_certificate)
1609 && opt_unset_or_noexpand(ob->tls_privatekey))
1612 || ( tls_set_watch(ob->tls_certificate, FALSE)
1613 && tls_set_watch(ob->tls_privatekey, FALSE)
1616 const uschar * pkey = ob->tls_privatekey;
1619 debug_printf("TLS: preloading client certs for transport '%s'\n", t->name);
1621 /* The state->lib_state.x509_cred is used for the certs load, and is the sole
1622 structure element used. So we can set up a dummy. The hoat arg only
1623 selects a retcode in case of fail, so any value */
1625 if (creds_load_client_certs(&tpt_dummy_state, dummy_host,
1626 ob->tls_certificate, pkey ? pkey : ob->tls_certificate,
1627 &dummy_errstr) == OK)
1628 ob->tls_preload.conn_certs = TRUE;
1633 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1635 if (opt_set_and_noexpand(ob->tls_verify_certificates))
1637 if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
1640 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1641 if (creds_load_cabundle(&tpt_dummy_state, ob->tls_verify_certificates,
1642 dummy_host, &dummy_errstr) != OK)
1644 ob->tls_preload.cabundle = TRUE;
1646 if (opt_set_and_noexpand(ob->tls_crl))
1648 if (!watch || tls_set_watch(ob->tls_crl, FALSE))
1650 DEBUG(D_tls) debug_printf("TLS: preloading CRL for transport '%s'\n", t->name);
1651 if (creds_load_crl(&tpt_dummy_state, ob->tls_crl, &dummy_errstr) != OK)
1653 ob->tls_preload.crl = TRUE;
1657 DEBUG(D_tls) debug_printf("TLS: not preloading CRL, for transport '%s'\n", t->name);
1662 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1664 /* We do not preload tls_require_ciphers to to the transport as it implicitly
1665 depends on DANE or plain usage. */
1671 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1672 /* Invalidate the creds cached, by dropping the current ones.
1673 Call when we notice one of the source files has changed. */
1676 tls_server_creds_invalidate(void)
1678 if (state_server.lib_state.pri_cache)
1679 gnutls_priority_deinit(state_server.lib_state.pri_cache);
1680 state_server.lib_state.pri_cache = NULL;
1682 if (state_server.lib_state.x509_cred)
1683 gnutls_certificate_free_credentials(state_server.lib_state.x509_cred);
1684 state_server.lib_state = null_tls_preload;
1689 tls_client_creds_invalidate(transport_instance * t)
1691 smtp_transport_options_block * ob = t->options_block;
1692 if (ob->tls_preload.x509_cred)
1693 gnutls_certificate_free_credentials(ob->tls_preload.x509_cred);
1694 ob->tls_preload = null_tls_preload;
1699 /*************************************************
1700 * Variables re-expanded post-SNI *
1701 *************************************************/
1703 /* Called from both server and client code, via tls_init(), and also from
1704 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
1706 We can tell the two apart by state->received_sni being non-NULL in callback.
1708 The callback should not call us unless state->trigger_sni_changes is true,
1709 which we are responsible for setting on the first pass through.
1712 state exim_gnutls_state_st *
1713 errstr error string pointer
1715 Returns: OK/DEFER/FAIL
1719 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
1722 const host_item *host = state->host; /* macro should be reconsidered? */
1723 const uschar *saved_tls_certificate = NULL;
1724 const uschar *saved_tls_privatekey = NULL;
1725 const uschar *saved_tls_verify_certificates = NULL;
1726 const uschar *saved_tls_crl = NULL;
1729 /* We check for tls_sni *before* expansion. */
1730 if (!host) /* server */
1731 if (!state->received_sni)
1733 if ( state->tls_certificate
1734 && ( Ustrstr(state->tls_certificate, US"tls_sni")
1735 || Ustrstr(state->tls_certificate, US"tls_in_sni")
1736 || Ustrstr(state->tls_certificate, US"tls_out_sni")
1739 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI\n");
1740 state->trigger_sni_changes = TRUE;
1743 else /* SNI callback case */
1745 /* useful for debugging */
1746 saved_tls_certificate = state->exp_tls_certificate;
1747 saved_tls_privatekey = state->exp_tls_privatekey;
1748 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1749 saved_tls_crl = state->exp_tls_crl;
1752 if (!state->lib_state.x509_cred)
1754 if ((rc = gnutls_certificate_allocate_credentials(
1755 (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))
1756 return tls_error_gnu(state, US"gnutls_certificate_allocate_credentials",
1758 creds_basic_init(state->lib_state.x509_cred, !host);
1762 /* remember: Expand_check_tlsvar() is expand_check() but fiddling with
1763 state members, assuming consistent naming; and expand_check() returns
1764 false if expansion failed, unless expansion was forced to fail. */
1766 /* check if we at least have a certificate, before doing expensive
1769 if (!state->lib_state.conn_certs)
1771 if (!Expand_check_tlsvar(tls_certificate, errstr))
1774 /* certificate is mandatory in server, optional in client */
1776 if ( !state->exp_tls_certificate
1777 || !*state->exp_tls_certificate
1780 return tls_install_selfsign(state, errstr);
1782 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1784 if (state->tls_privatekey && !Expand_check_tlsvar(tls_privatekey, errstr))
1787 /* tls_privatekey is optional, defaulting to same file as certificate */
1789 if (!state->tls_privatekey || !*state->tls_privatekey)
1791 state->tls_privatekey = state->tls_certificate;
1792 state->exp_tls_privatekey = state->exp_tls_certificate;
1795 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1798 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1799 state->exp_tls_certificate, state->exp_tls_privatekey);
1801 if (state->received_sni)
1802 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1803 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1806 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1807 load = FALSE; /* avoid re-loading the same certs */
1809 else /* unload the pre-SNI certs before loading new ones */
1811 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair\n");
1812 gnutls_certificate_free_keys(state->lib_state.x509_cred);
1817 ? creds_load_client_certs(state, host, state->exp_tls_certificate,
1818 state->exp_tls_privatekey, errstr)
1819 : creds_load_server_certs(state, state->exp_tls_certificate,
1820 state->exp_tls_privatekey,
1833 debug_printf("%s certs were preloaded\n", host ? "client" : "server");
1835 if (!state->tls_privatekey) state->tls_privatekey = state->tls_certificate;
1836 state->exp_tls_certificate = US state->tls_certificate;
1837 state->exp_tls_privatekey = US state->tls_privatekey;
1839 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1840 if (state->lib_state.ocsp_hook)
1841 gnutls_handshake_set_hook_function(state->session,
1842 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1847 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1848 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1849 error message is provided. However, if we just refrain from setting anything up
1850 in that case, certificate verification fails, which seems to be the correct
1853 if (!state->lib_state.cabundle)
1855 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1857 if (!Expand_check_tlsvar(tls_verify_certificates, errstr))
1859 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1860 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1861 state->exp_tls_verify_certificates = NULL;
1863 if (state->tls_crl && *state->tls_crl)
1864 if (!Expand_check_tlsvar(tls_crl, errstr))
1867 if (!(state->exp_tls_verify_certificates &&
1868 *state->exp_tls_verify_certificates))
1871 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1872 /* With no tls_verify_certificates, we ignore tls_crl too */
1879 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1882 rc = creds_load_cabundle(state, state->exp_tls_verify_certificates, host, errstr);
1883 if (rc != OK) return rc;
1888 debug_printf("%s CA bundle was preloaded\n", host ? "client" : "server");
1889 state->exp_tls_verify_certificates = US state->tls_verify_certificates;
1891 #ifdef SUPPORT_CA_DIR
1892 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1893 when using the directory-of-certs config model. */
1894 if (state->lib_state.ca_rdn_emulate)
1895 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1900 if (!state->lib_state.crl)
1902 if ( state->tls_crl && *state->tls_crl
1903 && state->exp_tls_crl && *state->exp_tls_crl)
1904 return creds_load_crl(state, state->exp_tls_crl, errstr);
1909 debug_printf("%s CRL was preloaded\n", host ? "client" : "server");
1910 state->exp_tls_crl = US state->tls_crl;
1919 /*************************************************
1920 * Set X.509 state variables *
1921 *************************************************/
1923 /* In GnuTLS, the registered cert/key are not replaced by a later
1924 set of a cert/key, so for SNI support we need a whole new x509_cred
1925 structure. Which means various other non-re-expanded pieces of state
1926 need to be re-set in the new struct, so the setting logic is pulled
1930 state exim_gnutls_state_st *
1931 errstr error string pointer
1933 Returns: OK/DEFER/FAIL
1937 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1940 const host_item *host = state->host; /* macro should be reconsidered? */
1942 #ifndef GNUTLS_AUTO_DHPARAMS
1943 /* Create D-H parameters, or read them from the cache file. This function does
1944 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1945 client-side params. */
1949 if (!dh_server_params)
1950 if ((rc = init_server_dh(errstr)) != OK) return rc;
1952 /* Unnecessary & discouraged with 3.6.0 or later */
1953 gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
1957 /* Link the credentials to the session. */
1959 if ((rc = gnutls_credentials_set(state->session,
1960 GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))
1961 return tls_error_gnu(state, US"gnutls_credentials_set", rc, errstr);
1966 /*************************************************
1967 * Initialize for GnuTLS *
1968 *************************************************/
1971 /* Called from both server and client code. In the case of a server, errors
1972 before actual TLS negotiation return DEFER.
1975 host connected host, if client; NULL if server
1976 ob tranport options block, if client; NULL if server
1977 require_ciphers tls_require_ciphers setting
1978 caller_state returned state-info structure
1979 errstr error string pointer
1981 Returns: OK/DEFER/FAIL
1986 const host_item *host,
1987 smtp_transport_options_block * ob,
1988 const uschar * require_ciphers,
1989 exim_gnutls_state_st **caller_state,
1993 exim_gnutls_state_st * state;
1997 if ( !exim_gnutls_base_init_done
1998 && (rc = tls_g_init(errstr)) != OK)
2003 /* For client-side sessions we allocate a context. This lets us run
2004 several in parallel. */
2006 int old_pool = store_pool;
2007 store_pool = POOL_PERM;
2008 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
2009 store_pool = old_pool;
2011 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2012 state->lib_state = ob->tls_preload;
2014 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
2015 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
2017 state->tls_certificate = ob->tls_certificate;
2018 state->tls_privatekey = ob->tls_privatekey;
2019 state->tls_sni = ob->tls_sni;
2020 state->tls_verify_certificates = ob->tls_verify_certificates;
2021 state->tls_crl = ob->tls_crl;
2025 /* Server operations always use the one state_server context. It is not
2026 shared because we have forked a fresh process for every receive. However it
2027 can get re-used for successive TLS sessions on a single TCP connection. */
2029 state = &state_server;
2031 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
2032 rc = gnutls_init(&state->session, GNUTLS_SERVER);
2034 state->tls_certificate = tls_certificate;
2035 state->tls_privatekey = tls_privatekey;
2036 state->tls_sni = NULL;
2037 state->tls_verify_certificates = tls_verify_certificates;
2038 state->tls_crl = tls_crl;
2041 return tls_error_gnu(state, US"gnutls_init", rc, errstr);
2043 state->tls_require_ciphers = require_ciphers;
2046 /* This handles the variables that might get re-expanded after TLS SNI;
2047 tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
2050 debug_printf("Expanding various TLS configuration options for session credentials\n");
2051 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
2053 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
2054 requires a new structure afterwards. */
2056 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
2058 /* set SNI in client, only */
2061 if (!expand_check(state->tls_sni, US"tls_out_sni", &state->tlsp->sni, errstr))
2063 if (state->tlsp->sni && *state->tlsp->sni)
2066 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
2067 sz = Ustrlen(state->tlsp->sni);
2068 if ((rc = gnutls_server_name_set(state->session,
2069 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
2070 return tls_error_gnu(state, US"gnutls_server_name_set", rc, errstr);
2073 else if (state->tls_sni)
2074 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
2075 "have an SNI set for a server [%s]\n", state->tls_sni);
2077 if (!state->lib_state.pri_string)
2079 const uschar * p = NULL;
2080 const char * errpos;
2082 /* This is the priority string support,
2083 http://www.gnutls.org/manual/html_node/Priority-Strings.html
2084 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
2085 This was backwards incompatible, but means Exim no longer needs to track
2086 all algorithms and provide string forms for them. */
2088 if (state->tls_require_ciphers && *state->tls_require_ciphers)
2090 if (!Expand_check_tlsvar(tls_require_ciphers, errstr))
2092 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
2094 p = state->exp_tls_require_ciphers;
2095 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
2099 if ((rc = creds_load_pristring(state, p, &errpos)))
2100 return tls_error_gnu(state, string_sprintf(
2101 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
2102 p, errpos - CS p, errpos),
2107 DEBUG(D_tls) debug_printf("cipher list preloaded\n");
2108 state->exp_tls_require_ciphers = US state->tls_require_ciphers;
2112 if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))
2113 return tls_error_gnu(state, US"gnutls_priority_set", rc, errstr);
2115 /* This also sets the server ticket expiration time to the same, and
2116 the STEK rotation time to 3x. */
2118 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
2120 /* Reduce security in favour of increased compatibility, if the admin
2121 decides to make that trade-off. */
2122 if (gnutls_compat_mode)
2124 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
2125 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
2126 gnutls_session_enable_compatibility_mode(state->session);
2128 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
2132 *caller_state = state;
2138 /*************************************************
2139 * Extract peer information *
2140 *************************************************/
2142 static const uschar *
2143 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
2144 gnutls_mac_algorithm_t mac)
2147 gnutls_kx_algorithm_t kx_i;
2148 gnutls_cipher_algorithm_t cipher_i;
2149 gnutls_mac_algorithm_t mac_i;
2152 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
2154 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
2155 return cipher_stdname(cs_id[0], cs_id[1]);
2161 /* Called from both server and client code.
2162 Only this is allowed to set state->peerdn and state->have_set_peerdn
2163 and we use that to detect double-calls.
2165 NOTE: the state blocks last while the TLS connection is up, which is fine
2166 for logging in the server side, but for the client side, we log after teardown
2167 in src/deliver.c. While the session is up, we can twist about states and
2168 repoint tls_* globals, but those variables used for logging or other variable
2169 expansion that happens _after_ delivery need to have a longer life-time.
2171 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
2172 doing this more than once per generation of a state context. We set them in
2173 the state context, and repoint tls_* to them. After the state goes away, the
2174 tls_* copies of the pointers remain valid and client delivery logging is happy.
2176 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
2180 state exim_gnutls_state_st *
2181 errstr pointer to error string
2183 Returns: OK/DEFER/FAIL
2187 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
2189 gnutls_session_t session = state->session;
2190 const gnutls_datum_t * cert_list;
2192 unsigned int cert_list_size = 0;
2193 gnutls_protocol_t protocol;
2194 gnutls_cipher_algorithm_t cipher;
2195 gnutls_kx_algorithm_t kx;
2196 gnutls_mac_algorithm_t mac;
2197 gnutls_certificate_type_t ct;
2198 gnutls_x509_crt_t crt;
2202 if (state->have_set_peerdn)
2204 state->have_set_peerdn = TRUE;
2206 state->peerdn = NULL;
2209 cipher = gnutls_cipher_get(session);
2210 protocol = gnutls_protocol_get_version(session);
2211 mac = gnutls_mac_get(session);
2213 #ifdef GNUTLS_TLS1_3
2214 protocol >= GNUTLS_TLS1_3 ? 0 :
2216 gnutls_kx_get(session);
2218 old_pool = store_pool;
2220 tls_support * tlsp = state->tlsp;
2221 store_pool = POOL_PERM;
2223 #ifdef SUPPORT_GNUTLS_SESS_DESC
2226 uschar * s = US gnutls_session_get_desc(session), c;
2228 /* Nikos M suggests we use this by preference. It returns like:
2229 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
2231 For partial back-compat, put a colon after the TLS version, replace the
2232 )-( grouping with __, replace in-group - with _ and append the :keysize. */
2234 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
2236 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
2238 tlsp->ver = string_copyn(g->s, g->ptr);
2239 for (uschar * p = US tlsp->ver; *p; p++)
2240 if (*p == '-') { *p = '\0'; break; } /* TLS1.0-PKIX -> TLS1.0 */
2242 g = string_catn(g, US":", 1);
2243 if (*s) s++; /* now on _ between groups */
2246 for (*++s && ++s; (c = *s) && c != ')'; s++)
2247 g = string_catn(g, c == '-' ? US"_" : s, 1);
2248 /* now on ) closing group */
2249 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
2250 /* now on _ between groups */
2252 g = string_catn(g, US":", 1);
2253 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
2254 state->ciphersuite = string_from_gstring(g);
2257 state->ciphersuite = string_sprintf("%s:%s:%d",
2258 gnutls_protocol_get_name(protocol),
2259 gnutls_cipher_suite_get_name(kx, cipher, mac),
2260 (int) gnutls_cipher_get_key_size(cipher) * 8);
2262 /* I don't see a way that spaces could occur, in the current GnuTLS
2263 code base, but it was a concern in the old code and perhaps older GnuTLS
2264 releases did return "TLS 1.0"; play it safe, just in case. */
2266 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
2267 tlsp->ver = string_copyn(state->ciphersuite,
2268 Ustrchr(state->ciphersuite, ':') - state->ciphersuite);
2271 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
2273 tlsp->cipher = state->ciphersuite;
2274 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
2276 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
2278 store_pool = old_pool;
2281 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
2283 if (!cert_list || cert_list_size == 0)
2285 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
2286 cert_list, cert_list_size);
2287 if (state->verify_requirement >= VERIFY_REQUIRED)
2288 return tls_error(US"certificate verification failed",
2289 US"no certificate received from peer", state->host, errstr);
2293 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
2295 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
2297 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
2298 if (state->verify_requirement >= VERIFY_REQUIRED)
2299 return tls_error(US"certificate verification not possible, unhandled type",
2300 ctn, state->host, errstr);
2304 #define exim_gnutls_peer_err(Label) \
2306 if (rc != GNUTLS_E_SUCCESS) \
2308 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
2309 (Label), gnutls_strerror(rc)); \
2310 if (state->verify_requirement >= VERIFY_REQUIRED) \
2311 return tls_error_gnu(state, (Label), rc, errstr); \
2316 rc = import_cert(&cert_list[0], &crt);
2317 exim_gnutls_peer_err(US"cert 0");
2319 state->tlsp->peercert = state->peercert = crt;
2322 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
2323 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
2325 exim_gnutls_peer_err(US"getting size for cert DN failed");
2326 return FAIL; /* should not happen */
2328 dn_buf = store_get_perm(sz, TRUE); /* tainted */
2329 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
2330 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
2332 state->peerdn = dn_buf;
2335 #undef exim_gnutls_peer_err
2341 /*************************************************
2342 * Verify peer certificate *
2343 *************************************************/
2345 /* Called from both server and client code.
2346 *Should* be using a callback registered with
2347 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
2348 the peer information, but that's too new for some OSes.
2351 state exim_gnutls_state_st *
2352 errstr where to put an error message
2355 FALSE if the session should be rejected
2356 TRUE if the cert is okay or we just don't care
2360 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
2365 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
2367 rc = peer_status(state, errstr);
2369 if (state->verify_requirement == VERIFY_NONE)
2372 if (rc != OK || !state->peerdn)
2374 verify = GNUTLS_CERT_INVALID;
2375 *errstr = US"certificate not supplied";
2381 if (state->verify_requirement == VERIFY_DANE && state->host)
2383 /* Using dane_verify_session_crt() would be easy, as it does it all for us
2384 including talking to a DNS resolver. But we want to do that bit ourselves
2385 as the testsuite intercepts and fakes its own DNS environment. */
2390 const gnutls_datum_t * certlist =
2391 gnutls_certificate_get_peers(state->session, &lsize);
2392 int usage = tls_out.tlsa_usage;
2394 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2395 /* Split the TLSA records into two sets, TA and EE selectors. Run the
2396 dane-verification separately so that we know which selector verified;
2397 then we know whether to do name-verification (needed for TA but not EE). */
2399 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
2400 { /* a mixed-usage bundle */
2405 for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
2408 dd = store_get(nrec * sizeof(uschar *), FALSE);
2409 ddl = store_get(nrec * sizeof(int), FALSE);
2412 if ((rc = dane_state_init(&s, 0)))
2415 for (usage = DANESSL_USAGE_DANE_EE;
2416 usage >= DANESSL_USAGE_DANE_TA; usage--)
2417 { /* take records with this usage */
2418 for (j = i = 0; i < nrec; i++)
2419 if (state->dane_data[i][0] == usage)
2421 dd[j] = state->dane_data[i];
2422 ddl[j++] = state->dane_data_len[i];
2429 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
2432 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
2433 gnutls_certificate_type_get(state->session),
2435 usage == DANESSL_USAGE_DANE_EE
2436 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2440 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
2442 else if (verify == 0) /* verification passed */
2450 if (rc) goto tlsa_prob;
2455 if ( (rc = dane_state_init(&s, 0))
2456 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
2458 || (rc = dane_verify_crt_raw(s, certlist, lsize,
2459 gnutls_certificate_type_get(state->session),
2461 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2462 usage == (1 << DANESSL_USAGE_DANE_EE)
2463 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
2472 if (verify != 0) /* verification failed */
2475 (void) dane_verification_status_print(verify, &str, 0);
2476 *errstr = US str.data; /* don't bother to free */
2480 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2481 /* If a TA-mode TLSA record was used for verification we must additionally
2482 verify the cert name (but not the CA chain). For EE-mode, skip it. */
2484 if (usage & (1 << DANESSL_USAGE_DANE_EE))
2487 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2490 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2491 /* Assume that the name on the A-record is the one that should be matching
2492 the cert. An alternate view is that the domain part of the email address
2493 is also permissible. */
2495 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2496 CS state->host->name))
2498 state->peer_dane_verified = state->peer_cert_verified = TRUE;
2503 #endif /*SUPPORT_DANE*/
2505 rc = gnutls_certificate_verify_peers2(state->session, &verify);
2508 /* Handle the result of verification. INVALID is set if any others are. */
2510 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
2512 state->peer_cert_verified = FALSE;
2515 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
2520 if (gnutls_certificate_verification_status_print(verify,
2521 gnutls_certificate_type_get(state->session), &txt, 0)
2522 == GNUTLS_E_SUCCESS)
2524 debug_printf("%s\n", txt.data);
2525 gnutls_free(txt.data);
2529 *errstr = verify & GNUTLS_CERT_REVOKED
2530 ? US"certificate revoked" : US"certificate invalid";
2534 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
2535 *errstr, state->peerdn ? state->peerdn : US"<unset>");
2537 if (state->verify_requirement >= VERIFY_REQUIRED)
2540 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
2545 /* Client side, check the server's certificate name versus the name on the
2546 A-record for the connection we made. What to do for server side - what name
2547 to use for client? We document that there is no such checking for server
2550 if ( state->exp_tls_verify_cert_hostnames
2551 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2552 CS state->exp_tls_verify_cert_hostnames)
2556 debug_printf("TLS certificate verification failed: cert name mismatch\n");
2557 if (state->verify_requirement >= VERIFY_REQUIRED)
2562 state->peer_cert_verified = TRUE;
2563 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
2564 state->peerdn ? state->peerdn : US"<unset>");
2568 state->tlsp->peerdn = state->peerdn;
2573 *errstr = string_sprintf("TLSA record problem: %s",
2574 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
2578 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
2585 /* ------------------------------------------------------------------------ */
2588 /* Logging function which can be registered with
2589 * gnutls_global_set_log_function()
2590 * gnutls_global_set_log_level() 0..9
2592 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2594 exim_gnutls_logger_cb(int level, const char *message)
2596 size_t len = strlen(message);
2599 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2602 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2603 message[len-1] == '\n' ? "" : "\n");
2608 /* Called after client hello, should handle SNI work.
2609 This will always set tls_sni (state->received_sni) if available,
2610 and may trigger presenting different certificates,
2611 if state->trigger_sni_changes is TRUE.
2613 Should be registered with
2614 gnutls_handshake_set_post_client_hello_function()
2616 "This callback must return 0 on success or a gnutls error code to terminate the
2619 For inability to get SNI information, we return 0.
2620 We only return non-zero if re-setup failed.
2621 Only used for server-side TLS.
2625 exim_sni_handling_cb(gnutls_session_t session)
2627 char sni_name[MAX_HOST_LEN];
2628 size_t data_len = MAX_HOST_LEN;
2629 exim_gnutls_state_st *state = &state_server;
2630 unsigned int sni_type;
2632 uschar * dummy_errstr;
2634 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2635 if (rc != GNUTLS_E_SUCCESS)
2638 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2639 debug_printf("TLS: no SNI presented in handshake\n");
2641 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2642 gnutls_strerror(rc), rc);
2646 if (sni_type != GNUTLS_NAME_DNS)
2648 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2652 /* We now have a UTF-8 string in sni_name */
2653 old_pool = store_pool;
2654 store_pool = POOL_PERM;
2655 state->received_sni = string_copy_taint(US sni_name, TRUE);
2656 store_pool = old_pool;
2658 /* We set this one now so that variable expansions below will work */
2659 state->tlsp->sni = state->received_sni;
2661 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2662 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2664 if (!state->trigger_sni_changes)
2667 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2669 /* If the setup of certs/etc failed before handshake, TLS would not have
2670 been offered. The best we can do now is abort. */
2671 return GNUTLS_E_APPLICATION_ERROR_MIN;
2674 rc = tls_set_remaining_x509(state, &dummy_errstr);
2675 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2682 #ifndef DISABLE_EVENT
2684 We use this callback to get observability and detail-level control
2685 for an exim TLS connection (either direction), raising a tls:cert event
2686 for each cert in the chain presented by the peer. Any event
2687 can deny verification.
2689 Return 0 for the handshake to continue or non-zero to terminate.
2693 verify_cb(gnutls_session_t session)
2695 const gnutls_datum_t * cert_list;
2696 unsigned int cert_list_size = 0;
2697 gnutls_x509_crt_t crt;
2700 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2702 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2703 while (cert_list_size--)
2705 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2707 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2708 cert_list_size, gnutls_strerror(rc));
2712 state->tlsp->peercert = crt;
2713 if ((yield = event_raise(state->event_action,
2714 US"tls:cert", string_sprintf("%d", cert_list_size))))
2716 log_write(0, LOG_MAIN,
2717 "SSL verify denied by event-action: depth=%d: %s",
2718 cert_list_size, yield);
2719 return 1; /* reject */
2721 state->tlsp->peercert = NULL;
2731 ddump(gnutls_datum_t * d)
2733 gstring * g = string_get((d->size+1) * 2);
2734 uschar * s = d->data;
2735 for (unsigned i = d->size; i > 0; i--, s++)
2737 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2738 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2744 post_handshake_debug(exim_gnutls_state_st * state)
2746 #ifdef SUPPORT_GNUTLS_SESS_DESC
2747 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2750 #ifdef SUPPORT_GNUTLS_KEYLOG
2751 # ifdef EXIM_HAVE_TLS1_3
2752 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2757 gnutls_datum_t c, s;
2759 /* For TLS1.2 we only want the client random and the master secret */
2760 gnutls_session_get_random(state->session, &c, &s);
2761 gnutls_session_get_master_secret(state->session, &s);
2764 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2767 debug_printf("To get keying info for TLS1.3 is hard:\n"
2768 " Set environment variable SSLKEYLOGFILE to a filename relative to the spool directory,\n"
2769 " and make sure it is writable by the Exim runtime user.\n"
2770 " Add SSLKEYLOGFILE to keep_environment in the exim config.\n"
2771 " Start Exim as root.\n"
2772 " If using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
2773 " (works for TLS1.2 also, and saves cut-paste into file).\n"
2774 " Trying to use add_environment for this will not work\n");
2779 #ifdef EXIM_HAVE_TLS_RESUME
2781 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2782 unsigned incoming, const gnutls_datum_t * msg)
2784 DEBUG(D_tls) debug_printf("newticket cb\n");
2785 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2790 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2792 /* Should the server offer session resumption? */
2793 tls_in.resumption = RESUME_SUPPORTED;
2794 if (verify_check_host(&tls_resumption_hosts) == OK)
2797 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2798 an offered resumption is unacceptable. We lose one resumption per ticket
2799 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2800 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2801 least they go out in a single packet. */
2803 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2804 &server_sessticket_key)))
2805 tls_in.resumption |= RESUME_SERVER_TICKET;
2808 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2810 /* Try to tell if we see a ticket request */
2811 gnutls_handshake_set_hook_function(state->session,
2812 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2817 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2819 if (gnutls_session_resumption_requested(state->session))
2821 /* This tells us the client sent a full ticket. We use a
2822 callback on session-ticket request, elsewhere, to tell
2823 if a client asked for a ticket. */
2825 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2826 DEBUG(D_tls) debug_printf("client requested resumption\n");
2828 if (gnutls_session_is_resumed(state->session))
2830 tls_in.resumption |= RESUME_USED;
2831 DEBUG(D_tls) debug_printf("Session resumed\n");
2834 #endif /* EXIM_HAVE_TLS_RESUME */
2837 #ifdef EXIM_HAVE_ALPN
2838 /* Expand and convert an Exim list to a gnutls_datum list. False return for fail.
2839 NULL plist return for silent no-ALPN.
2843 tls_alpn_plist(const uschar * tls_alpn, const gnutls_datum_t ** plist, unsigned * plen,
2848 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
2853 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
2858 const uschar * list = exp_alpn;
2864 while (string_nextinlist(&list, &sep, NULL, 0)) cnt++;
2866 p = store_get(sizeof(gnutls_datum_t) * cnt, is_tainted(exp_alpn));
2868 for (int i = 0; s = string_nextinlist(&list, &sep, NULL, 0); i++)
2869 { p[i].data = s; p[i].size = Ustrlen(s); }
2870 *plist = (*plen = cnt) ? p : NULL;
2876 tls_server_set_acceptable_alpns(exim_gnutls_state_st * state, uschar ** errstr)
2879 const gnutls_datum_t * plist;
2882 if (tls_alpn_plist(tls_alpn, &plist, &plen, errstr) && plist)
2884 /* This seems to be only mandatory if the client sends an ALPN extension;
2885 not trying ALPN is ok. Need to decide how to support server-side must-alpn. */
2887 server_seen_alpn = 0;
2888 if (!(rc = gnutls_alpn_set_protocols(state->session, plist, plen,
2889 GNUTLS_ALPN_MANDATORY)))
2890 gnutls_handshake_set_hook_function(state->session,
2891 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2894 debug_printf("setting alpn protocols: %s\n", US gnutls_strerror(rc));
2897 #endif /* EXIM_HAVE_ALPN */
2899 /* ------------------------------------------------------------------------ */
2900 /* Exported functions */
2905 /*************************************************
2906 * Start a TLS session in a server *
2907 *************************************************/
2909 /* This is called when Exim is running as a server, after having received
2910 the STARTTLS command. It must respond to that command, and then negotiate
2914 errstr pointer to error string
2916 Returns: OK on success
2917 DEFER for errors before the start of the negotiation
2918 FAIL for errors during the negotiation; the server can't
2923 tls_server_start(uschar ** errstr)
2926 exim_gnutls_state_st * state = NULL;
2928 /* Check for previous activation */
2929 if (tls_in.active.sock >= 0)
2931 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2932 smtp_printf("554 Already in TLS\r\n", FALSE);
2936 /* Initialize the library. If it fails, it will already have logged the error
2937 and sent an SMTP response. */
2939 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2942 #ifdef MEASURE_TIMING
2944 gettimeofday(&t0, NULL);
2947 if ((rc = tls_init(NULL, NULL,
2948 tls_require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2950 #ifdef MEASURE_TIMING
2951 report_time_since(&t0, US"server tls_init (delta)");
2955 #ifdef EXIM_HAVE_ALPN
2956 tls_server_set_acceptable_alpns(state, errstr);
2959 #ifdef EXIM_HAVE_TLS_RESUME
2960 tls_server_resume_prehandshake(state);
2963 /* If this is a host for which certificate verification is mandatory or
2964 optional, set up appropriately. */
2966 if (verify_check_host(&tls_verify_hosts) == OK)
2969 debug_printf("TLS: a client certificate will be required\n");
2970 state->verify_requirement = VERIFY_REQUIRED;
2971 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2973 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2976 debug_printf("TLS: a client certificate will be requested but not required\n");
2977 state->verify_requirement = VERIFY_OPTIONAL;
2978 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2983 debug_printf("TLS: a client certificate will not be requested\n");
2984 state->verify_requirement = VERIFY_NONE;
2985 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2988 #ifndef DISABLE_EVENT
2991 state->event_action = event_action;
2992 gnutls_session_set_ptr(state->session, state);
2993 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
2997 /* Register SNI handling; always, even if not in tls_certificate, so that the
2998 expansion variable $tls_sni is always available. */
3000 gnutls_handshake_set_post_client_hello_function(state->session,
3001 exim_sni_handling_cb);
3003 /* Set context and tell client to go ahead, except in the case of TLS startup
3004 on connection, where outputting anything now upsets the clients and tends to
3005 make them disconnect. We need to have an explicit fflush() here, to force out
3006 the response. Other smtp_printf() calls do not need it, because in non-TLS
3007 mode, the fflush() happens when smtp_getc() is called. */
3009 if (!state->tlsp->on_connect)
3011 smtp_printf("220 TLS go ahead\r\n", FALSE);
3015 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3016 that the GnuTLS library doesn't.
3017 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
3018 to set (and clear down afterwards) up a pull-timeout callback function that does
3019 a select, so we're no better off unless avoiding signals becomes an issue. */
3021 gnutls_transport_set_ptr2(state->session,
3022 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
3023 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
3024 state->fd_in = fileno(smtp_in);
3025 state->fd_out = fileno(smtp_out);
3027 sigalrm_seen = FALSE;
3028 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3030 rc = gnutls_handshake(state->session);
3031 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3034 if (rc != GNUTLS_E_SUCCESS)
3036 /* It seems that, except in the case of a timeout, we have to close the
3037 connection right here; otherwise if the other end is running OpenSSL it hangs
3038 until the server times out. */
3042 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
3043 gnutls_db_remove_session(state->session);
3047 tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
3048 (void) gnutls_alert_send_appropriate(state->session, rc);
3049 gnutls_deinit(state->session);
3050 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3051 state->lib_state = null_tls_preload;
3053 shutdown(state->fd_out, SHUT_WR);
3054 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
3055 (void)fclose(smtp_out);
3056 (void)fclose(smtp_in);
3057 smtp_out = smtp_in = NULL;
3063 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3064 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3065 tls_in.ext_master_secret = TRUE;
3068 #ifdef EXIM_HAVE_TLS_RESUME
3069 tls_server_resume_posthandshake(state);
3072 DEBUG(D_tls) post_handshake_debug(state);
3074 #ifdef EXIM_HAVE_ALPN
3075 if (server_seen_alpn > 0)
3078 { /* The client offered ALPN. See what was negotiated. */
3079 gnutls_datum_t p = {.size = 0};
3080 int rc = gnutls_alpn_get_selected_protocol(state->session, &p);
3082 debug_printf("ALPN negotiated: %.*s\n", (int)p.size, p.data);
3084 debug_printf("getting alpn protocol: %s\n", US gnutls_strerror(rc));
3088 else if (server_seen_alpn == 0)
3089 if (verify_check_host(&hosts_require_alpn) == OK)
3091 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
3092 tls_error(US"handshake", US"ALPN required but not negotiated", NULL, errstr);
3096 DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n");
3098 DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n");
3101 /* Verify after the fact */
3103 if (!verify_certificate(state, errstr))
3105 if (state->verify_requirement != VERIFY_OPTIONAL)
3107 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
3111 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
3115 /* Sets various Exim expansion variables; always safe within server */
3117 extract_exim_vars_from_tls_state(state);
3119 /* TLS has been set up. Adjust the input functions to read via TLS,
3120 and initialize appropriately. */
3122 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3124 receive_getc = tls_getc;
3125 receive_getbuf = tls_getbuf;
3126 receive_get_cache = tls_get_cache;
3127 receive_ungetc = tls_ungetc;
3128 receive_feof = tls_feof;
3129 receive_ferror = tls_ferror;
3130 receive_smtp_buffered = tls_smtp_buffered;
3139 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
3140 smtp_transport_options_block * ob)
3142 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3144 state->exp_tls_verify_cert_hostnames =
3146 string_domain_utf8_to_alabel(host->certname, NULL);
3151 debug_printf("TLS: server cert verification includes hostname: \"%s\"\n",
3152 state->exp_tls_verify_cert_hostnames);
3160 /* Given our list of RRs from the TLSA lookup, build a lookup block in
3161 GnuTLS-DANE's preferred format. Hang it on the state str for later
3162 use in DANE verification.
3164 We point at the dnsa data not copy it, so it must remain valid until
3165 after verification is done.*/
3168 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
3172 const char ** dane_data;
3173 int * dane_data_len;
3176 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3177 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3178 ) if (rr->type == T_TLSA) i++;
3180 dane_data = store_get(i * sizeof(uschar *), FALSE);
3181 dane_data_len = store_get(i * sizeof(int), FALSE);
3184 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3185 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3186 ) if (rr->type == T_TLSA && rr->size > 3)
3188 const uschar * p = rr->data;
3189 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
3190 uint8_t usage = p[0], sel = p[1], type = p[2];
3193 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
3195 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
3196 || (sel != 0 && sel != 1)
3201 case 0: /* Full: cannot check at present */
3203 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
3205 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
3210 tls_out.tlsa_usage |= 1<<usage;
3211 dane_data[i] = CS p;
3212 dane_data_len[i++] = rr->size;
3215 if (!i) return FALSE;
3217 dane_data[i] = NULL;
3218 dane_data_len[i] = 0;
3220 state->dane_data = (char * const *)dane_data;
3221 state->dane_data_len = dane_data_len;
3228 #ifdef EXIM_HAVE_TLS_RESUME
3229 /* On the client, get any stashed session for the given IP from hints db
3230 and apply it to the ssl-connection for attempted resumption. Although
3231 there is a gnutls_session_ticket_enable_client() interface it is
3232 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
3233 by deafult". There seems to be no way to disable them, so even hosts not
3234 enabled by the transport option will be sent a ticket request. We will
3235 however avoid storing and retrieving session information. */
3238 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
3239 host_item * host, smtp_transport_options_block * ob)
3241 tlsp->resumption = RESUME_SUPPORTED;
3242 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3244 dbdata_tls_session * dt;
3246 open_db dbblock, * dbm_file;
3249 debug_printf("check for resumable session for %s\n", host->address);
3250 tlsp->host_resumable = TRUE;
3251 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3252 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
3254 /* Key for the db is the IP. We'd like to filter the retrieved session
3255 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
3257 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
3258 if (!(rc = gnutls_session_set_data(session,
3259 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
3261 DEBUG(D_tls) debug_printf("good session\n");
3262 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3264 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
3265 US gnutls_strerror(rc));
3266 dbfn_close(dbm_file);
3273 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
3275 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
3276 but this flag is not set until the second. TLS 1.3 it's the other way about.
3277 Keep both calls as the session data cannot be extracted before handshake
3280 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
3285 DEBUG(D_tls) debug_printf("server offered session ticket\n");
3286 tlsp->ticket_received = TRUE;
3287 tlsp->resumption |= RESUME_SERVER_TICKET;
3289 if (tlsp->host_resumable)
3290 if (!(rc = gnutls_session_get_data2(session, &tkt)))
3292 open_db dbblock, * dbm_file;
3293 int dlen = sizeof(dbdata_tls_session) + tkt.size;
3294 dbdata_tls_session * dt = store_get(dlen, TRUE);
3296 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
3297 memcpy(dt->session, tkt.data, tkt.size);
3298 gnutls_free(tkt.data);
3300 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3302 /* key for the db is the IP */
3303 dbfn_delete(dbm_file, host->address);
3304 dbfn_write(dbm_file, host->address, dt, dlen);
3305 dbfn_close(dbm_file);
3308 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
3312 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
3317 /* With a TLS1.3 session, the ticket(s) are not seen until
3318 the first data read is attempted. And there's often two of them.
3319 Pick them up with this callback. We are also called for 1.2
3323 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
3324 unsigned incoming, const gnutls_datum_t * msg)
3326 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
3327 tls_support * tlsp = state->tlsp;
3329 DEBUG(D_tls) debug_printf("newticket cb\n");
3331 if (!tlsp->ticket_received)
3332 tls_save_session(tlsp, sess, state->host);
3338 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
3339 tls_support * tlsp, host_item * host,
3340 smtp_transport_options_block * ob)
3342 gnutls_session_set_ptr(state->session, state);
3343 gnutls_handshake_set_hook_function(state->session,
3344 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
3346 tls_retrieve_session(tlsp, state->session, host, ob);
3350 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
3351 tls_support * tlsp, host_item * host)
3353 if (gnutls_session_is_resumed(state->session))
3355 DEBUG(D_tls) debug_printf("Session resumed\n");
3356 tlsp->resumption |= RESUME_USED;
3359 tls_save_session(tlsp, state->session, host);
3361 #endif /* !DISABLE_TLS_RESUME */
3364 /*************************************************
3365 * Start a TLS session in a client *
3366 *************************************************/
3368 /* Called from the smtp transport after STARTTLS has been accepted.
3371 cctx connection context
3372 conn_args connection details
3373 cookie datum for randomness (not used)
3374 tlsp record details of channel configuration here; must be non-NULL
3375 errstr error string pointer
3377 Returns: TRUE for success with TLS session context set in smtp context,
3382 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3383 void * cookie ARG_UNUSED,
3384 tls_support * tlsp, uschar ** errstr)
3386 host_item * host = conn_args->host; /* for msgs and option-tests */
3387 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3388 smtp_transport_options_block * ob = tb
3389 ? (smtp_transport_options_block *)tb->options_block
3390 : &smtp_transport_option_defaults;
3392 exim_gnutls_state_st * state = NULL;
3393 uschar * cipher_list = NULL;
3395 #ifndef DISABLE_OCSP
3397 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3398 BOOL request_ocsp = require_ocsp ? TRUE
3399 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3402 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
3405 /* If dane is flagged, have either request or require dane for this host, and
3406 a TLSA record found. Therefore, dane verify required. Which implies cert must
3407 be requested and supplied, dane verify must pass, and cert verify irrelevant
3408 (incl. hostnames), and (caller handled) require_tls and sni=$domain */
3410 if (conn_args->dane && ob->dane_require_tls_ciphers)
3412 /* not using Expand_check_tlsvar because not yet in state */
3413 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3414 &cipher_list, errstr))
3416 cipher_list = cipher_list && *cipher_list
3417 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
3422 cipher_list = ob->tls_require_ciphers;
3425 #ifdef MEASURE_TIMING
3427 gettimeofday(&t0, NULL);
3430 if (tls_init(host, ob, cipher_list, &state, tlsp, errstr) != OK)
3433 #ifdef MEASURE_TIMING
3434 report_time_since(&t0, US"client tls_init (delta)");
3439 #ifdef EXIM_HAVE_ALPN
3441 const gnutls_datum_t * plist;
3444 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
3447 if (gnutls_alpn_set_protocols(state->session, plist, plen, 0) != 0)
3449 tls_error(US"alpn init", NULL, state->host, errstr);
3453 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
3456 log_write(0, LOG_MAIN, "ALPN unusable with this GnuTLS library version; ignoring \"%s\"\n",
3461 int dh_min_bits = ob->tls_dh_min_bits;
3462 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
3465 debug_printf("WARNING: tls_dh_min_bits far too low,"
3466 " clamping %d up to %d\n",
3467 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
3468 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
3471 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
3472 " acceptable bits to %d\n",
3474 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
3477 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
3478 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
3479 the specified host patterns if one of them is defined */
3482 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
3485 debug_printf("TLS: server certificate DANE required\n");
3486 state->verify_requirement = VERIFY_DANE;
3487 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3491 if ( ( state->exp_tls_verify_certificates
3492 && !ob->tls_verify_hosts
3493 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
3495 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3498 tls_client_setup_hostname_checks(host, state, ob);
3500 debug_printf("TLS: server certificate verification required\n");
3501 state->verify_requirement = VERIFY_REQUIRED;
3502 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
3504 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3506 tls_client_setup_hostname_checks(host, state, ob);
3508 debug_printf("TLS: server certificate verification optional\n");
3509 state->verify_requirement = VERIFY_OPTIONAL;
3510 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
3515 debug_printf("TLS: server certificate verification not required\n");
3516 state->verify_requirement = VERIFY_NONE;
3517 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
3520 #ifndef DISABLE_OCSP
3521 /* supported since GnuTLS 3.1.3 */
3524 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
3525 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
3526 NULL, 0, NULL)) != OK)
3528 tls_error_gnu(state, US"cert-status-req", rc, errstr);
3531 tlsp->ocsp = OCSP_NOT_RESP;
3535 #ifdef EXIM_HAVE_TLS_RESUME
3536 tls_client_resume_prehandshake(state, tlsp, host, ob);
3539 #ifndef DISABLE_EVENT
3540 if (tb && tb->event_action)
3542 state->event_action = tb->event_action;
3543 gnutls_session_set_ptr(state->session, state);
3544 gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
3548 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
3549 state->fd_in = cctx->sock;
3550 state->fd_out = cctx->sock;
3552 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
3553 /* There doesn't seem to be a built-in timeout on connection. */
3555 sigalrm_seen = FALSE;
3556 ALARM(ob->command_timeout);
3558 rc = gnutls_handshake(state->session);
3559 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
3562 if (rc != GNUTLS_E_SUCCESS)
3566 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
3567 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
3570 tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
3574 DEBUG(D_tls) post_handshake_debug(state);
3578 if (!verify_certificate(state, errstr))
3580 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
3584 #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
3585 if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
3586 tlsp->ext_master_secret = TRUE;
3589 #ifndef DISABLE_OCSP
3594 gnutls_datum_t stapling;
3595 gnutls_ocsp_resp_t resp;
3596 gnutls_datum_t printed;
3600 # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
3601 (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
3603 (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
3606 if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0
3607 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
3608 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
3611 debug_printf("%.4096s", printed.data);
3612 gnutls_free(printed.data);
3615 (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
3617 (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
3620 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
3622 tlsp->ocsp = OCSP_FAILED;
3623 tls_error(US"certificate status check failed", NULL, state->host, errstr);
3629 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
3630 tlsp->ocsp = OCSP_VFIED;
3635 #ifdef EXIM_HAVE_TLS_RESUME
3636 tls_client_resume_posthandshake(state, tlsp, host);
3639 #ifdef EXIM_HAVE_ALPN
3640 if (ob->tls_alpn) /* We requested. See what was negotiated. */
3642 gnutls_datum_t p = {.size = 0};
3644 if (gnutls_alpn_get_selected_protocol(state->session, &p) == 0)
3645 { DEBUG(D_tls) debug_printf("ALPN negotiated: '%.*s'\n", (int)p.size, p.data); }
3646 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
3648 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
3649 tls_error(US"handshake", US"ALPN required but not negotiated", state->host, errstr);
3653 DEBUG(D_tls) debug_printf("No ALPN negotiated");
3657 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
3659 extract_exim_vars_from_tls_state(state);
3661 cctx->tls_ctx = state;
3670 ct_ctx client TLS context pointer, or NULL for the one global server context
3674 tls_shutdown_wr(void * ct_ctx)
3676 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3677 tls_support * tlsp = state->tlsp;
3679 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3681 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
3683 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
3684 gnutls_bye(state->session, GNUTLS_SHUT_WR);
3687 /*************************************************
3688 * Close down a TLS session *
3689 *************************************************/
3691 /* This is also called from within a delivery subprocess forked from the
3692 daemon, to shut down the TLS library, without actually doing a shutdown (which
3693 would tamper with the TLS session in the parent process).
3696 ct_ctx client context pointer, or NULL for the one global server context
3697 do_shutdown 0 no data-flush or TLS close-alert
3698 1 if TLS close-alert is to be sent,
3699 2 if also response to be waited for (2s timeout)
3705 tls_close(void * ct_ctx, int do_shutdown)
3707 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3708 tls_support * tlsp = state->tlsp;
3710 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3714 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3715 do_shutdown > 1 ? " (with response-wait)" : "");
3717 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
3720 gnutls_bye(state->session, do_shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
3724 if (!ct_ctx) /* server */
3726 receive_getc = smtp_getc;
3727 receive_getbuf = smtp_getbuf;
3728 receive_get_cache = smtp_get_cache;
3729 receive_ungetc = smtp_ungetc;
3730 receive_feof = smtp_feof;
3731 receive_ferror = smtp_ferror;
3732 receive_smtp_buffered = smtp_buffered;
3735 gnutls_deinit(state->session);
3736 gnutls_certificate_free_credentials(state->lib_state.x509_cred);
3737 state->lib_state = null_tls_preload;
3739 tlsp->active.sock = -1;
3740 tlsp->active.tls_ctx = NULL;
3741 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3742 tlsp->channelbinding = NULL;
3745 if (state->xfer_buffer) store_free(state->xfer_buffer);
3752 tls_refill(unsigned lim)
3754 exim_gnutls_state_st * state = &state_server;
3757 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, buffersize=%u)\n",
3758 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
3760 sigalrm_seen = FALSE;
3761 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3765 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
3766 MIN(ssl_xfer_buffer_size, lim));
3767 while (inbytes == GNUTLS_E_AGAIN);
3769 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3771 if (had_command_timeout) /* set by signal handler */
3772 smtp_command_timeout_exit(); /* does not return */
3773 if (had_command_sigterm)
3774 smtp_command_sigterm_exit();
3775 if (had_data_timeout)
3776 smtp_data_timeout_exit();
3777 if (had_data_sigint)
3778 smtp_data_sigint_exit();
3780 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3781 TLS session has been closed down, not that the socket itself has been closed
3782 down. Revert to non-TLS handling. */
3786 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3787 state->xfer_error = TRUE;
3791 else if (inbytes == 0)
3793 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3794 tls_close(NULL, TLS_NO_SHUTDOWN);
3798 /* Handle genuine errors */
3800 else if (inbytes < 0)
3802 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3803 record_io_error(state, (int) inbytes, US"recv", NULL);
3804 state->xfer_error = TRUE;
3807 #ifndef DISABLE_DKIM
3808 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3810 state->xfer_buffer_hwm = (int) inbytes;
3811 state->xfer_buffer_lwm = 0;
3815 /*************************************************
3816 * TLS version of getc *
3817 *************************************************/
3819 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3820 it refills the buffer via the GnuTLS reading function.
3821 Only used by the server-side TLS.
3823 This feeds DKIM and should be used for all message-body reads.
3825 Arguments: lim Maximum amount to read/buffer
3826 Returns: the next character or EOF
3830 tls_getc(unsigned lim)
3832 exim_gnutls_state_st * state = &state_server;
3834 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3835 if (!tls_refill(lim))
3836 return state->xfer_error ? EOF : smtp_getc(lim);
3838 /* Something in the buffer; return next uschar */
3840 return state->xfer_buffer[state->xfer_buffer_lwm++];
3844 tls_getbuf(unsigned * len)
3846 exim_gnutls_state_st * state = &state_server;
3850 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3851 if (!tls_refill(*len))
3853 if (!state->xfer_error) return smtp_getbuf(len);
3858 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3860 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3861 state->xfer_buffer_lwm += size;
3870 #ifndef DISABLE_DKIM
3871 exim_gnutls_state_st * state = &state_server;
3872 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3874 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3880 tls_could_read(void)
3882 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3883 || gnutls_record_check_pending(state_server.session) > 0;
3887 /*************************************************
3888 * Read bytes from TLS channel *
3889 *************************************************/
3891 /* This does not feed DKIM, so if the caller uses this for reading message body,
3892 then the caller must feed DKIM.
3895 ct_ctx client context pointer, or NULL for the one global server context
3899 Returns: the number of bytes read
3900 -1 after a failed read, including EOF
3904 tls_read(void * ct_ctx, uschar *buff, size_t len)
3906 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3912 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3914 debug_printf("*** PROBABLY A BUG *** " \
3915 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3916 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3919 debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, len=" SIZE_T_FMT ")\n",
3920 state->session, buff, len);
3924 inbytes = gnutls_record_recv(state->session, buff, len);
3925 while (inbytes == GNUTLS_E_AGAIN);
3927 if (inbytes > 0) return inbytes;
3930 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3934 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3935 record_io_error(state, (int)inbytes, US"recv", NULL);
3944 /*************************************************
3945 * Write bytes down TLS channel *
3946 *************************************************/
3950 ct_ctx client context pointer, or NULL for the one global server context
3953 more more data expected soon
3955 Calling with len zero and more unset will flush buffered writes. The buff
3956 argument can be null for that case.
3958 Returns: the number of bytes after a successful write,
3959 -1 after a failed write
3963 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3967 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3970 if (more && !state->corked)
3972 DEBUG(D_tls) debug_printf("gnutls_record_cork(session=%p)\n", state->session);
3973 gnutls_record_cork(state->session);
3974 state->corked = TRUE;
3978 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3979 buff, left, more ? ", more" : "");
3983 DEBUG(D_tls) debug_printf("gnutls_record_send(session=%p, buffer=%p, left=" SIZE_T_FMT ")\n",
3984 state->session, buff, left);
3988 outbytes = gnutls_record_send(state->session, buff, left);
3989 while (outbytes == GNUTLS_E_AGAIN);
3991 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
3995 #ifdef GNUTLS_E_PREMATURE_TERMINATION
3996 if ( outbytes == GNUTLS_E_PREMATURE_TERMINATION && errno == ECONNRESET
3997 && !ct_ctx && f.smtp_in_quit
3999 { /* Outlook, dammit */
4000 if (LOGGING(protocol_detail))
4001 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4002 " SMTP response and TLS close\n", sender_host_address);
4004 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4005 " client reset TCP before TLS close\n", sender_host_address);
4010 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
4011 record_io_error(state, outbytes, US"send", NULL);
4017 record_io_error(state, 0, US"send", US"TLS channel closed on write");
4028 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
4034 if (!more && state->corked)
4036 DEBUG(D_tls) debug_printf("gnutls_record_uncork(session=%p)\n", state->session);
4038 /* We can't use GNUTLS_RECORD_WAIT here, as it retries on
4039 GNUTLS_E_AGAIN || GNUTLS_E_INTR, which would break our timeout set by alarm().
4040 The GNUTLS_E_AGAIN should not happen ever, as our sockets are blocking anyway.
4041 But who knows. (That all relies on the fact that GNUTLS_E_INTR and GNUTLS_E_AGAIN
4042 match the EINTR and EAGAIN errno values.) */
4043 outbytes = gnutls_record_uncork(state->session, 0);
4044 while (outbytes == GNUTLS_E_AGAIN);
4048 record_io_error(state, len, US"uncork", NULL);
4052 state->corked = FALSE;
4062 /*************************************************
4063 * Random number generation *
4064 *************************************************/
4066 /* Pseudo-random number generation. The result is not expected to be
4067 cryptographically strong but not so weak that someone will shoot themselves
4068 in the foot using it as a nonce in input in some email header scheme or
4069 whatever weirdness they'll twist this into. The result should handle fork()
4070 and avoid repeating sequences. OpenSSL handles that for us.
4074 Returns a random number in range [0, max-1]
4077 #ifdef HAVE_GNUTLS_RND
4079 vaguely_random_number(int max)
4083 uschar smallbuf[sizeof(r)];
4088 needed_len = sizeof(r);
4089 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4090 asked for a number less than 10. */
4092 for (r = max, i = 0; r; ++i)
4098 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
4101 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback\n");
4102 return vaguely_random_number_fallback(max);
4105 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4108 /* We don't particularly care about weighted results; if someone wants
4109 * smooth distribution and cares enough then they should submit a patch then. */
4112 #else /* HAVE_GNUTLS_RND */
4114 vaguely_random_number(int max)
4116 return vaguely_random_number_fallback(max);
4118 #endif /* HAVE_GNUTLS_RND */
4123 /*************************************************
4124 * Let tls_require_ciphers be checked at startup *
4125 *************************************************/
4127 /* The tls_require_ciphers option, if set, must be something which the
4130 Returns: NULL on success, or error message
4134 tls_validate_require_cipher(void)
4137 uschar *expciphers = NULL;
4138 gnutls_priority_t priority_cache;
4140 uschar * dummy_errstr;
4142 #ifdef GNUTLS_AUTO_GLOBAL_INIT
4143 # define validate_check_rc(Label) do { \
4144 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \
4145 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
4146 # define return_deinit(Label) do { return (Label); } while (0)
4148 # define validate_check_rc(Label) do { \
4149 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
4150 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
4151 # define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
4154 if (exim_gnutls_base_init_done)
4155 log_write(0, LOG_MAIN|LOG_PANIC,
4156 "already initialised GnuTLS, Exim developer bug");
4158 #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
4159 if (!gnutls_allow_auto_pkcs11)
4161 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
4162 validate_check_rc(US"gnutls_pkcs11_init");
4165 #ifndef GNUTLS_AUTO_GLOBAL_INIT
4166 rc = gnutls_global_init();
4167 validate_check_rc(US"gnutls_global_init()");
4169 exim_gnutls_base_init_done = TRUE;
4171 if (!(tls_require_ciphers && *tls_require_ciphers))
4172 return_deinit(NULL);
4174 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4176 return_deinit(US"failed to expand tls_require_ciphers");
4178 if (!(expciphers && *expciphers))
4179 return_deinit(NULL);
4182 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4184 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
4185 validate_check_rc(string_sprintf(
4186 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
4187 expciphers, errpos - CS expciphers, errpos));
4189 #undef return_deinit
4190 #undef validate_check_rc
4191 #ifndef GNUTLS_AUTO_GLOBAL_INIT
4192 gnutls_global_deinit();
4201 /*************************************************
4202 * Report the library versions. *
4203 *************************************************/
4205 /* See a description in tls-openssl.c for an explanation of why this exists.
4207 Arguments: a FILE* to print the results to
4212 tls_version_report(FILE *f)
4214 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
4217 gnutls_check_version(NULL));
4220 #endif /*!MACRO_PREDEF*/
4223 /* End of tls-gnu.c */