1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Copyright (c) Phil Pennock 2012 */
10 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
11 one of the available supported implementations. This file is #included into
12 tls.c when USE_GNUTLS has been set.
14 The code herein is a revamp of GnuTLS integration using the current APIs; the
15 original tls-gnu.c was based on a patch which was contributed by Nikos
16 Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as
19 APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
20 which is not widely deployed by OS vendors. Will note issues below, which may
21 assist in updating the code in the future. Another sources of hints is
22 mod_gnutls for Apache (SNI callback registration and handling).
24 Keeping client and server variables more split than before and is currently
25 the norm, in anticipation of TLS in ACL callouts.
27 I wanted to switch to gnutls_certificate_set_verify_function() so that
28 certificate rejection could happen during handshake where it belongs, rather
29 than being dropped afterwards, but that was introduced in 2.10.0 and Debian
30 (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
32 (I wasn't looking for libraries quite that old, when updating to get rid of
33 compiler warnings of deprecated APIs. If it turns out that a lot of the rest
34 require current GnuTLS, then we'll drop support for the ancient libraries).
37 #include <gnutls/gnutls.h>
38 /* needed for cert checks in verification and DN extraction: */
39 #include <gnutls/x509.h>
40 /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
41 #include <gnutls/crypto.h>
43 /* needed to disable PKCS11 autoload unless requested */
44 #if GNUTLS_VERSION_NUMBER >= 0x020c00
45 # include <gnutls/pkcs11.h>
46 # define SUPPORT_PARAM_TO_PK_BITS
48 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
49 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
52 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
53 # warning "GnuTLS library version too old; tls:cert event unsupported"
54 # define DISABLE_EVENT
56 #if GNUTLS_VERSION_NUMBER >= 0x030306
57 # define SUPPORT_CA_DIR
59 # undef SUPPORT_CA_DIR
61 #if GNUTLS_VERSION_NUMBER >= 0x030014
62 # define SUPPORT_SYSDEFAULT_CABUNDLE
64 #if GNUTLS_VERSION_NUMBER >= 0x030104
65 # define GNUTLS_CERT_VFY_STATUS_PRINT
67 #if GNUTLS_VERSION_NUMBER >= 0x030109
70 #if GNUTLS_VERSION_NUMBER >= 0x03010a
71 # define SUPPORT_GNUTLS_SESS_DESC
73 #if GNUTLS_VERSION_NUMBER >= 0x030500
74 # define SUPPORT_GNUTLS_KEYLOG
76 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
77 # define SUPPORT_SRV_OCSP_STACK
79 #if GNUTLS_VERSION_NUMBER >= 0x030603
80 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
84 # if GNUTLS_VERSION_NUMBER >= 0x030000
85 # define DANESSL_USAGE_DANE_TA 2
86 # define DANESSL_USAGE_DANE_EE 3
88 # error GnuTLS version too early for DANE
90 # if GNUTLS_VERSION_NUMBER < 0x999999
91 # define GNUTLS_BROKEN_DANE_VALIDATION
95 #ifdef EXPERIMENTAL_TLS_RESUME
96 # if GNUTLS_VERSION_NUMBER < 0x030603
97 # error GNUTLS version too early for session-resumption
102 # include <gnutls/ocsp.h>
105 # include <gnutls/dane.h>
108 #include "tls-cipher-stdname.c"
115 # ifdef EXPERIMENTAL_TLS_RESUME
116 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
125 gnutls_global_set_audit_log_function()
128 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
131 /* Local static variables for GnuTLS */
133 /* Values for verify_requirement */
135 enum peer_verify_requirement
136 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
138 /* This holds most state for server or client; with this, we can set up an
139 outbound TLS-enabled connection in an ACL callout, while not stomping all
140 over the TLS variables available for expansion.
142 Some of these correspond to variables in globals.c; those variables will
143 be set to point to content in one of these instances, as appropriate for
144 the stage of the process lifetime.
146 Not handled here: global tls_channelbinding_b64.
149 typedef struct exim_gnutls_state {
150 gnutls_session_t session;
151 gnutls_certificate_credentials_t x509_cred;
152 gnutls_priority_t priority_cache;
153 enum peer_verify_requirement verify_requirement;
156 BOOL peer_cert_verified;
157 BOOL peer_dane_verified;
158 BOOL trigger_sni_changes;
159 BOOL have_set_peerdn;
160 const struct host_item *host; /* NULL if server */
161 gnutls_x509_crt_t peercert;
164 uschar *received_sni;
166 const uschar *tls_certificate;
167 const uschar *tls_privatekey;
168 const uschar *tls_sni; /* client send only, not received */
169 const uschar *tls_verify_certificates;
170 const uschar *tls_crl;
171 const uschar *tls_require_ciphers;
173 uschar *exp_tls_certificate;
174 uschar *exp_tls_privatekey;
175 uschar *exp_tls_verify_certificates;
177 uschar *exp_tls_require_ciphers;
178 const uschar *exp_tls_verify_cert_hostnames;
179 #ifndef DISABLE_EVENT
180 uschar *event_action;
183 char * const * dane_data;
184 const int * dane_data_len;
187 tls_support *tlsp; /* set in tls_init() */
192 BOOL xfer_eof; /*XXX never gets set! */
194 } exim_gnutls_state_st;
196 static const exim_gnutls_state_st exim_gnutls_state_init = {
197 /* all elements not explicitly intialised here get 0/NULL/FALSE */
202 /* Not only do we have our own APIs which don't pass around state, assuming
203 it's held in globals, GnuTLS doesn't appear to let us register callback data
204 for callbacks, or as part of the session, so we have to keep a "this is the
205 context we're currently dealing with" pointer and rely upon being
206 single-threaded to keep from processing data on an inbound TLS connection while
207 talking to another TLS connection for an outbound check. This does mean that
208 there's no way for heart-beats to be responded to, for the duration of the
210 XXX But see gnutls_session_get_ptr()
213 static exim_gnutls_state_st state_server;
215 /* dh_params are initialised once within the lifetime of a process using TLS;
216 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
217 don't want to repeat this. */
219 static gnutls_dh_params_t dh_server_params = NULL;
221 static int ssl_session_timeout = 7200; /* Two hours */
223 static const uschar * const exim_default_gnutls_priority = US"NORMAL";
225 /* Guard library core initialisation */
227 static BOOL exim_gnutls_base_init_done = FALSE;
230 static BOOL gnutls_buggy_ocsp = FALSE;
231 static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
234 #ifdef EXPERIMENTAL_TLS_RESUME
235 static gnutls_datum_t server_sessticket_key;
238 /* ------------------------------------------------------------------------ */
241 #define MAX_HOST_LEN 255
243 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
244 the library logging; a value less than 0 disables the calls to set up logging
245 callbacks. GNuTLS also looks for an environment variable - except not for
246 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
247 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
248 but the env var must be added to /etc/sudoers too. */
249 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
250 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
253 #ifndef EXIM_CLIENT_DH_MIN_BITS
254 # define EXIM_CLIENT_DH_MIN_BITS 1024
257 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
258 can ask for a bit-strength. Without that, we stick to the constant we had
260 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
261 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
264 #define expand_check_tlsvar(Varname, errstr) \
265 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
267 #if GNUTLS_VERSION_NUMBER >= 0x020c00
268 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
269 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
270 # define HAVE_GNUTLS_RND
271 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
272 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
273 * isn't available sometimes, so this needs to become a conditional
274 * compilation; the sanest way to deal with this being a problem on
275 * older OSes is to block it in the Local/Makefile with this compiler
277 # ifndef AVOID_GNUTLS_PKCS11
278 # define HAVE_GNUTLS_PKCS11
279 # endif /* AVOID_GNUTLS_PKCS11 */
285 /* ------------------------------------------------------------------------ */
286 /* Callback declarations */
288 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
289 static void exim_gnutls_logger_cb(int level, const char *message);
292 static int exim_sni_handling_cb(gnutls_session_t session);
294 #if !defined(DISABLE_OCSP)
295 static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
296 gnutls_datum_t * ocsp_response);
299 #ifdef EXPERIMENTAL_TLS_RESUME
301 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
302 unsigned incoming, const gnutls_datum_t * msg);
306 /* Daemon one-time initialisation */
308 tls_daemon_init(void)
310 #ifdef EXPERIMENTAL_TLS_RESUME
311 /* We are dependent on the GnuTLS implementation of the Session Ticket
312 encryption; both the strength and the key rotation period. We hope that
313 the strength at least matches that of the ciphersuite (but GnuTLS does not
316 static BOOL once = FALSE;
319 gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
320 if (f.running_in_test_harness) ssl_session_timeout = 6;
324 /* ------------------------------------------------------------------------ */
325 /* Static functions */
327 /*************************************************
329 *************************************************/
331 /* Called from lots of places when errors occur before actually starting to do
332 the TLS handshake, that is, while the session is still in clear. Always returns
333 DEFER for a server and FAIL for a client so that most calls can use "return
334 tls_error(...)" to do this processing and then give an appropriate return. A
335 single function is used for both server and client, because it is called from
336 some shared functions.
339 prefix text to include in the logged error
340 msg additional error string (may be NULL)
341 usually obtained from gnutls_strerror()
342 host NULL if setting up a server;
343 the connected host if setting up a client
344 errstr pointer to returned error string
346 Returns: OK/DEFER/FAIL
350 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
354 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
355 return host ? FAIL : DEFER;
360 tls_error_gnu(const uschar *prefix, int err, const host_item *host,
363 return tls_error(prefix, US gnutls_strerror(err), host, errstr);
367 tls_error_sys(const uschar *prefix, int err, const host_item *host,
370 return tls_error(prefix, US strerror(err), host, errstr);
374 /*************************************************
375 * Deal with logging errors during I/O *
376 *************************************************/
378 /* We have to get the identity of the peer from saved data.
381 state the current GnuTLS exim state container
382 rc the GnuTLS error code, or 0 if it's a local error
383 when text identifying read or write
384 text local error text when rc is 0
390 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
395 if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
396 msg = string_sprintf("A TLS fatal alert has been received: %s",
397 US gnutls_alert_get_name(gnutls_alert_get(state->session)));
399 msg = US gnutls_strerror(rc);
401 (void) tls_error(when, msg, state->host, &errstr);
404 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
405 state->host->name, state->host->address, errstr);
408 uschar * conn_info = smtp_get_connection_info();
409 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
410 /* I'd like to get separated H= here, but too hard for now */
411 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
418 /*************************************************
419 * Set various Exim expansion vars *
420 *************************************************/
422 #define exim_gnutls_cert_err(Label) \
425 if (rc != GNUTLS_E_SUCCESS) \
427 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
428 (Label), gnutls_strerror(rc)); \
434 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
438 rc = gnutls_x509_crt_init(crtp);
439 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
441 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
442 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
447 #undef exim_gnutls_cert_err
450 /* We set various Exim global variables from the state, once a session has
451 been established. With TLS callouts, may need to change this to stack
452 variables, or just re-call it with the server state after client callout
455 Make sure anything set here is unset in tls_getc().
459 tls_bits strength indicator
460 tls_certificate_verified bool indicator
461 tls_channelbinding_b64 for some SASL mechanisms
463 tls_peercert pointer to library internal
465 tls_sni a (UTF-8) string
466 tls_ourcert pointer to library internal
469 state the relevant exim_gnutls_state_st *
473 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
475 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
478 gnutls_datum_t channel;
480 tls_support * tlsp = state->tlsp;
482 tlsp->active.sock = state->fd_out;
483 tlsp->active.tls_ctx = state;
485 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
487 tlsp->certificate_verified = state->peer_cert_verified;
489 tlsp->dane_verified = state->peer_dane_verified;
492 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
493 only available for use for authenticators while this TLS session is running. */
495 tls_channelbinding_b64 = NULL;
496 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
499 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
500 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
503 old_pool = store_pool;
504 store_pool = POOL_PERM;
505 tls_channelbinding_b64 = b64encode(CUS channel.data, (int)channel.size);
506 store_pool = old_pool;
507 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
511 /* peercert is set in peer_status() */
512 tlsp->peerdn = state->peerdn;
513 tlsp->sni = state->received_sni;
515 /* record our certificate */
517 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
518 gnutls_x509_crt_t crt;
520 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
527 /*************************************************
528 * Setup up DH parameters *
529 *************************************************/
531 /* Generating the D-H parameters may take a long time. They only need to
532 be re-generated every so often, depending on security policy. What we do is to
533 keep these parameters in a file in the spool directory. If the file does not
534 exist, we generate them. This means that it is easy to cause a regeneration.
536 The new file is written as a temporary file and renamed, so that an incomplete
537 file is never present. If two processes both compute some new parameters, you
538 waste a bit of effort, but it doesn't seem worth messing around with locking to
541 Returns: OK/DEFER/FAIL
545 init_server_dh(uschar ** errstr)
548 unsigned int dh_bits;
550 uschar filename_buf[PATH_MAX];
551 uschar *filename = NULL;
553 uschar *exp_tls_dhparam;
554 BOOL use_file_in_spool = FALSE;
555 host_item *host = NULL; /* dummy for macros */
557 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n");
559 if ((rc = gnutls_dh_params_init(&dh_server_params)))
560 return tls_error_gnu(US"gnutls_dh_params_init", rc, host, errstr);
565 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
568 if (!exp_tls_dhparam)
570 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
571 m.data = US std_dh_prime_default();
572 m.size = Ustrlen(m.data);
574 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
575 use_file_in_spool = TRUE;
576 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
578 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
581 else if (exp_tls_dhparam[0] != '/')
583 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
584 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
585 m.size = Ustrlen(m.data);
588 filename = exp_tls_dhparam;
592 if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
593 return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
594 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
598 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
599 /* If you change this constant, also change dh_param_fn_ext so that we can use a
600 different filename and ensure we have sufficient bits. */
602 if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
603 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
605 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
608 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
610 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
614 /* Some clients have hard-coded limits. */
615 if (dh_bits > tls_dh_max_bits)
618 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
620 dh_bits = tls_dh_max_bits;
623 if (use_file_in_spool)
625 if (!string_format(filename_buf, sizeof(filename_buf),
626 "%s/gnutls-params-%d", spool_directory, dh_bits))
627 return tls_error(US"overlong filename", NULL, NULL, errstr);
628 filename = filename_buf;
631 /* Open the cache file for reading and if successful, read it and set up the
634 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
640 if (fstat(fd, &statbuf) < 0) /* EIO */
644 return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
646 if (!S_ISREG(statbuf.st_mode))
649 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
651 if (!(fp = fdopen(fd, "rb")))
655 return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
656 saved_errno, NULL, errstr);
659 m.size = statbuf.st_size;
660 if (!(m.data = store_malloc(m.size)))
663 return tls_error_sys(US"malloc failed", errno, NULL, errstr);
665 if (!(sz = fread(m.data, m.size, 1, fp)))
670 return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
674 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
677 return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
678 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
681 /* If the file does not exist, fall through to compute new data and cache it.
682 If there was any other opening error, it is serious. */
684 else if (errno == ENOENT)
688 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
691 return tls_error(string_open_failed(errno, "\"%s\" for reading", filename),
694 /* If ret < 0, either the cache file does not exist, or the data it contains
695 is not useful. One particular case of this is when upgrading from an older
696 release of Exim in which the data was stored in a different format. We don't
697 try to be clever and support both formats; we just regenerate new data in this
703 unsigned int dh_bits_gen = dh_bits;
705 if ((PATH_MAX - Ustrlen(filename)) < 10)
706 return tls_error(US"Filename too long to generate replacement",
707 filename, NULL, errstr);
709 temp_fn = string_copy(US"%s.XXXXXXX");
710 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
711 return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
712 (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
714 /* GnuTLS overshoots!
715 * If we ask for 2236, we might get 2237 or more.
716 * But there's no way to ask GnuTLS how many bits there really are.
717 * We can ask how many bits were used in a TLS session, but that's it!
718 * The prime itself is hidden behind too much abstraction.
719 * So we ask for less, and proceed on a wing and a prayer.
720 * First attempt, subtracted 3 for 2233 and got 2240.
722 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
724 dh_bits_gen = dh_bits - 10;
726 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
731 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
733 if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
734 return tls_error_gnu(US"gnutls_dh_params_generate2", rc, host, errstr);
736 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
737 and I confirmed that a NULL call to get the size first is how the GnuTLS
738 sample apps handle this. */
742 if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
743 GNUTLS_X509_FMT_PEM, m.data, &sz))
744 && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
745 return tls_error_gnu(US"gnutls_dh_params_export_pkcs3(NULL) sizing",
748 if (!(m.data = store_malloc(m.size)))
749 return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
751 /* this will return a size 1 less than the allocation size above */
752 if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
756 return tls_error_gnu(US"gnutls_dh_params_export_pkcs3() real", rc, host, errstr);
758 m.size = sz; /* shrink by 1, probably */
760 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
763 return tls_error_sys(US"TLS cache write D-H params failed",
764 errno, NULL, errstr);
767 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
768 return tls_error_sys(US"TLS cache write D-H params final newline failed",
769 errno, NULL, errstr);
771 if ((rc = close(fd)))
772 return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
774 if (Urename(temp_fn, filename) < 0)
775 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
776 temp_fn, filename), errno, NULL, errstr);
778 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
781 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
788 /* Create and install a selfsigned certificate, for use in server mode */
791 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
793 gnutls_x509_crt_t cert = NULL;
795 gnutls_x509_privkey_t pkey = NULL;
796 const uschar * where;
799 where = US"initialising pkey";
800 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
802 where = US"initialising cert";
803 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
805 where = US"generating pkey";
806 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
807 #ifdef SUPPORT_PARAM_TO_PK_BITS
808 # ifndef GNUTLS_SEC_PARAM_MEDIUM
809 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
811 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
818 where = US"configuring cert";
820 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
821 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
822 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
823 || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */
824 || (rc = gnutls_x509_crt_set_key(cert, pkey))
826 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
827 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
828 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
829 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
830 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
831 GNUTLS_OID_X520_COMMON_NAME, 0,
832 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
836 where = US"signing cert";
837 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
839 where = US"installing selfsign cert";
841 if ((rc = gnutls_certificate_set_x509_key(state->x509_cred, &cert, 1, pkey)))
847 if (cert) gnutls_x509_crt_deinit(cert);
848 if (pkey) gnutls_x509_privkey_deinit(pkey);
852 rc = tls_error_gnu(where, rc, NULL, errstr);
859 /* Add certificate and key, from files.
862 Zero or negative: good. Negate value for certificate index if < 0.
863 Greater than zero: FAIL or DEFER code.
867 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
868 uschar * certfile, uschar * keyfile, uschar ** errstr)
870 int rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
871 CS certfile, CS keyfile, GNUTLS_X509_FMT_PEM);
873 return tls_error_gnu(
874 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
880 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
881 /* Make a note that we saw a status-request */
883 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
884 const unsigned char *data, unsigned size)
886 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
887 if (tls_id == 5) /* status_request */
889 DEBUG(D_tls) debug_printf("Seen status_request extension\n");
890 tls_in.ocsp = OCSP_NOT_RESP;
895 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
897 tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
898 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
900 /* Call fn for each extension seen. 3.6.3 onwards */
901 return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
902 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
906 /* Callback for certificate-status, on server. We sent stapled OCSP. */
908 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
909 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
911 DEBUG(D_tls) debug_printf("Sending certificate-status\n");
912 #ifdef SUPPORT_SRV_OCSP_STACK
913 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
914 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
916 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
921 /* Callback for handshake messages, on server */
923 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
924 unsigned incoming, const gnutls_datum_t * msg)
928 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
929 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
930 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
932 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
933 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
934 #ifdef EXPERIMENTAL_TLS_RESUME
935 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
936 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
945 tls_server_testharness_ocsp_fiddle(void)
947 extern char ** environ;
948 if (environ) for (uschar ** p = USS environ; *p; p++)
949 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
951 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
952 exim_testharness_disable_ocsp_validity_check = TRUE;
956 /*************************************************
957 * Variables re-expanded post-SNI *
958 *************************************************/
960 /* Called from both server and client code, via tls_init(), and also from
961 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
963 We can tell the two apart by state->received_sni being non-NULL in callback.
965 The callback should not call us unless state->trigger_sni_changes is true,
966 which we are responsible for setting on the first pass through.
969 state exim_gnutls_state_st *
970 errstr error string pointer
972 Returns: OK/DEFER/FAIL
976 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
980 const host_item *host = state->host; /* macro should be reconsidered? */
981 uschar *saved_tls_certificate = NULL;
982 uschar *saved_tls_privatekey = NULL;
983 uschar *saved_tls_verify_certificates = NULL;
984 uschar *saved_tls_crl = NULL;
987 /* We check for tls_sni *before* expansion. */
988 if (!host) /* server */
989 if (!state->received_sni)
991 if ( state->tls_certificate
992 && ( Ustrstr(state->tls_certificate, US"tls_sni")
993 || Ustrstr(state->tls_certificate, US"tls_in_sni")
994 || Ustrstr(state->tls_certificate, US"tls_out_sni")
997 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
998 state->trigger_sni_changes = TRUE;
1003 /* useful for debugging */
1004 saved_tls_certificate = state->exp_tls_certificate;
1005 saved_tls_privatekey = state->exp_tls_privatekey;
1006 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1007 saved_tls_crl = state->exp_tls_crl;
1010 if ((rc = gnutls_certificate_allocate_credentials(&state->x509_cred)))
1011 return tls_error_gnu(US"gnutls_certificate_allocate_credentials",
1014 #ifdef SUPPORT_SRV_OCSP_STACK
1015 gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2);
1018 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
1019 state members, assuming consistent naming; and expand_check() returns
1020 false if expansion failed, unless expansion was forced to fail. */
1022 /* check if we at least have a certificate, before doing expensive
1025 if (!expand_check_tlsvar(tls_certificate, errstr))
1028 /* certificate is mandatory in server, optional in client */
1030 if ( !state->exp_tls_certificate
1031 || !*state->exp_tls_certificate
1034 return tls_install_selfsign(state, errstr);
1036 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1038 if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr))
1041 /* tls_privatekey is optional, defaulting to same file as certificate */
1043 if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
1045 state->tls_privatekey = state->tls_certificate;
1046 state->exp_tls_privatekey = state->exp_tls_certificate;
1050 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1052 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1053 state->exp_tls_certificate, state->exp_tls_privatekey);
1055 if (state->received_sni)
1056 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1057 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1060 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1064 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
1067 if (!host) /* server */
1069 const uschar * clist = state->exp_tls_certificate;
1070 const uschar * klist = state->exp_tls_privatekey;
1071 const uschar * olist;
1072 int csep = 0, ksep = 0, osep = 0, cnt = 0;
1073 uschar * cfile, * kfile, * ofile;
1075 #ifndef DISABLE_OCSP
1076 if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr))
1081 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1083 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1084 return tls_error(US"cert/key setup: out of keys", NULL, host, errstr);
1085 else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr)))
1089 int gnutls_cert_index = -rc;
1090 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n", gnutls_cert_index, cfile);
1092 /* Set the OCSP stapling server info */
1094 #ifndef DISABLE_OCSP
1097 if (gnutls_buggy_ocsp)
1100 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1102 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1104 DEBUG(D_tls) debug_printf("OCSP response file = %s\n", ofile);
1106 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1107 if (f.running_in_test_harness) tls_server_testharness_ocsp_fiddle();
1109 if (!exim_testharness_disable_ocsp_validity_check)
1111 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1112 state->x509_cred, CCS ofile, gnutls_cert_index,
1113 GNUTLS_X509_FMT_DER)) < 0)
1114 return tls_error_gnu(
1115 US"gnutls_certificate_set_ocsp_status_request_file2",
1118 /* Arrange callbacks for OCSP request observability */
1120 gnutls_handshake_set_hook_function(state->session,
1121 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1124 # elif defined(SUPPORT_SRV_OCSP_STACK)
1125 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1126 state->x509_cred, gnutls_cert_index,
1127 server_ocsp_stapling_cb, ofile)))
1128 return tls_error_gnu(
1129 US"gnutls_certificate_set_ocsp_status_request_function2",
1137 debug_printf("oops; multiple OCSP files not supported\n");
1140 gnutls_certificate_set_ocsp_status_request_function(
1141 state->x509_cred, server_ocsp_stapling_cb, ofile);
1145 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1147 #endif /* DISABLE_OCSP */
1152 if (0 < (rc = tls_add_certfile(state, host,
1153 state->exp_tls_certificate, state->exp_tls_privatekey, errstr)))
1155 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1158 } /* tls_certificate */
1161 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1162 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1163 error message is provided. However, if we just refrain from setting anything up
1164 in that case, certificate verification fails, which seems to be the correct
1167 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1169 if (!expand_check_tlsvar(tls_verify_certificates, errstr))
1171 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1172 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1173 state->exp_tls_verify_certificates = NULL;
1175 if (state->tls_crl && *state->tls_crl)
1176 if (!expand_check_tlsvar(tls_crl, errstr))
1179 if (!(state->exp_tls_verify_certificates &&
1180 *state->exp_tls_verify_certificates))
1183 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1184 /* With no tls_verify_certificates, we ignore tls_crl too */
1191 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1195 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1196 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1197 cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
1201 if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
1203 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
1204 "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
1209 #ifndef SUPPORT_CA_DIR
1210 /* The test suite passes in /dev/null; we could check for that path explicitly,
1211 but who knows if someone has some weird FIFO which always dumps some certs, or
1212 other weirdness. The thing we really want to check is that it's not a
1213 directory, since while OpenSSL supports that, GnuTLS does not.
1214 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1215 if (S_ISDIR(statbuf.st_mode))
1218 debug_printf("verify certificates path is a dir: \"%s\"\n",
1219 state->exp_tls_verify_certificates);
1220 log_write(0, LOG_MAIN|LOG_PANIC,
1221 "tls_verify_certificates \"%s\" is a directory",
1222 state->exp_tls_verify_certificates);
1227 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1228 state->exp_tls_verify_certificates, statbuf.st_size);
1230 if (statbuf.st_size == 0)
1233 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1239 #ifdef SUPPORT_CA_DIR
1240 (statbuf.st_mode & S_IFMT) == S_IFDIR
1242 gnutls_certificate_set_x509_trust_dir(state->x509_cred,
1243 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
1246 gnutls_certificate_set_x509_trust_file(state->x509_cred,
1247 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
1249 #ifdef SUPPORT_CA_DIR
1250 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1251 when using the directory-of-certs config model. */
1253 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1254 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1259 return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr);
1261 debug_printf("Added %d certificate authorities.\n", cert_count);
1263 if (state->tls_crl && *state->tls_crl &&
1264 state->exp_tls_crl && *state->exp_tls_crl)
1266 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
1267 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
1268 CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM)) < 0)
1269 return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file",
1270 cert_count, host, errstr);
1272 DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
1281 /*************************************************
1282 * Set X.509 state variables *
1283 *************************************************/
1285 /* In GnuTLS, the registered cert/key are not replaced by a later
1286 set of a cert/key, so for SNI support we need a whole new x509_cred
1287 structure. Which means various other non-re-expanded pieces of state
1288 need to be re-set in the new struct, so the setting logic is pulled
1292 state exim_gnutls_state_st *
1293 errstr error string pointer
1295 Returns: OK/DEFER/FAIL
1299 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1302 const host_item *host = state->host; /* macro should be reconsidered? */
1304 /* Create D-H parameters, or read them from the cache file. This function does
1305 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1306 client-side params. */
1310 if (!dh_server_params)
1311 if ((rc = init_server_dh(errstr)) != OK) return rc;
1312 gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
1315 /* Link the credentials to the session. */
1317 if ((rc = gnutls_credentials_set(state->session,
1318 GNUTLS_CRD_CERTIFICATE, state->x509_cred)))
1319 return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr);
1324 /*************************************************
1325 * Initialize for GnuTLS *
1326 *************************************************/
1329 #ifndef DISABLE_OCSP
1332 tls_is_buggy_ocsp(void)
1335 uschar maj, mid, mic;
1337 s = CUS gnutls_check_version(NULL);
1341 while (*s && *s != '.') s++;
1342 mid = atoi(CCS ++s);
1349 while (*s && *s != '.') s++;
1350 mic = atoi(CCS ++s);
1351 return mic <= (mid == 3 ? 16 : 3);
1360 /* Called from both server and client code. In the case of a server, errors
1361 before actual TLS negotiation return DEFER.
1364 host connected host, if client; NULL if server
1365 certificate certificate file
1366 privatekey private key file
1367 sni TLS SNI to send, sometimes when client; else NULL
1370 require_ciphers tls_require_ciphers setting
1371 caller_state returned state-info structure
1372 errstr error string pointer
1374 Returns: OK/DEFER/FAIL
1379 const host_item *host,
1380 const uschar *certificate,
1381 const uschar *privatekey,
1385 const uschar *require_ciphers,
1386 exim_gnutls_state_st **caller_state,
1390 exim_gnutls_state_st * state;
1393 const char * errpos;
1396 if (!exim_gnutls_base_init_done)
1398 DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
1400 #ifdef HAVE_GNUTLS_PKCS11
1401 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1402 which loads modules from a config file, which sounds good and may be wanted
1403 by some sysadmin, but also means in common configurations that GNOME keyring
1404 environment variables are used and so breaks for users calling mailq.
1405 To prevent this, we init PKCS11 first, which is the documented approach. */
1406 if (!gnutls_allow_auto_pkcs11)
1407 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
1408 return tls_error_gnu(US"gnutls_pkcs11_init", rc, host, errstr);
1411 if ((rc = gnutls_global_init()))
1412 return tls_error_gnu(US"gnutls_global_init", rc, host, errstr);
1414 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1417 gnutls_global_set_log_function(exim_gnutls_logger_cb);
1418 /* arbitrarily chosen level; bump up to 9 for more */
1419 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
1423 #ifndef DISABLE_OCSP
1424 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
1425 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
1428 exim_gnutls_base_init_done = TRUE;
1433 /* For client-side sessions we allocate a context. This lets us run
1434 several in parallel. */
1435 int old_pool = store_pool;
1436 store_pool = POOL_PERM;
1437 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
1438 store_pool = old_pool;
1440 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1442 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
1443 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
1447 state = &state_server;
1448 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1450 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
1451 rc = gnutls_init(&state->session, GNUTLS_SERVER);
1454 return tls_error_gnu(US"gnutls_init", rc, host, errstr);
1458 state->tls_certificate = certificate;
1459 state->tls_privatekey = privatekey;
1460 state->tls_require_ciphers = require_ciphers;
1461 state->tls_sni = sni;
1462 state->tls_verify_certificates = cas;
1463 state->tls_crl = crl;
1465 /* This handles the variables that might get re-expanded after TLS SNI;
1466 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1469 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1470 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
1472 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1473 requires a new structure afterwards. */
1475 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
1477 /* set SNI in client, only */
1480 if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni, errstr))
1482 if (state->tlsp->sni && *state->tlsp->sni)
1485 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
1486 sz = Ustrlen(state->tlsp->sni);
1487 if ((rc = gnutls_server_name_set(state->session,
1488 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
1489 return tls_error_gnu(US"gnutls_server_name_set", rc, host, errstr);
1492 else if (state->tls_sni)
1493 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
1494 "have an SNI set for a server [%s]\n", state->tls_sni);
1496 /* This is the priority string support,
1497 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1498 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1499 This was backwards incompatible, but means Exim no longer needs to track
1500 all algorithms and provide string forms for them. */
1503 if (state->tls_require_ciphers && *state->tls_require_ciphers)
1505 if (!expand_check_tlsvar(tls_require_ciphers, errstr))
1507 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
1509 p = state->exp_tls_require_ciphers;
1510 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
1515 p = exim_default_gnutls_priority;
1517 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1520 if ((rc = gnutls_priority_init(&state->priority_cache, CCS p, &errpos)))
1521 return tls_error_gnu(string_sprintf(
1522 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1523 p, errpos - CS p, errpos),
1526 if ((rc = gnutls_priority_set(state->session, state->priority_cache)))
1527 return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr);
1529 /* This also sets the server ticket expiration time to the same, and
1530 the STEK rotation time to 3x. */
1532 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
1534 /* Reduce security in favour of increased compatibility, if the admin
1535 decides to make that trade-off. */
1536 if (gnutls_compat_mode)
1538 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1539 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
1540 gnutls_session_enable_compatibility_mode(state->session);
1542 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1546 *caller_state = state;
1552 /*************************************************
1553 * Extract peer information *
1554 *************************************************/
1556 static const uschar *
1557 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
1558 gnutls_mac_algorithm_t mac)
1561 gnutls_kx_algorithm_t kx_i;
1562 gnutls_cipher_algorithm_t cipher_i;
1563 gnutls_mac_algorithm_t mac_i;
1566 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
1568 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
1569 return cipher_stdname(cs_id[0], cs_id[1]);
1575 /* Called from both server and client code.
1576 Only this is allowed to set state->peerdn and state->have_set_peerdn
1577 and we use that to detect double-calls.
1579 NOTE: the state blocks last while the TLS connection is up, which is fine
1580 for logging in the server side, but for the client side, we log after teardown
1581 in src/deliver.c. While the session is up, we can twist about states and
1582 repoint tls_* globals, but those variables used for logging or other variable
1583 expansion that happens _after_ delivery need to have a longer life-time.
1585 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1586 doing this more than once per generation of a state context. We set them in
1587 the state context, and repoint tls_* to them. After the state goes away, the
1588 tls_* copies of the pointers remain valid and client delivery logging is happy.
1590 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1594 state exim_gnutls_state_st *
1595 errstr pointer to error string
1597 Returns: OK/DEFER/FAIL
1601 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
1603 gnutls_session_t session = state->session;
1604 const gnutls_datum_t * cert_list;
1606 unsigned int cert_list_size = 0;
1607 gnutls_protocol_t protocol;
1608 gnutls_cipher_algorithm_t cipher;
1609 gnutls_kx_algorithm_t kx;
1610 gnutls_mac_algorithm_t mac;
1611 gnutls_certificate_type_t ct;
1612 gnutls_x509_crt_t crt;
1616 if (state->have_set_peerdn)
1618 state->have_set_peerdn = TRUE;
1620 state->peerdn = NULL;
1623 cipher = gnutls_cipher_get(session);
1624 protocol = gnutls_protocol_get_version(session);
1625 mac = gnutls_mac_get(session);
1627 #ifdef GNUTLS_TLS1_3
1628 protocol >= GNUTLS_TLS1_3 ? 0 :
1630 gnutls_kx_get(session);
1632 old_pool = store_pool;
1634 tls_support * tlsp = state->tlsp;
1635 store_pool = POOL_PERM;
1637 #ifdef SUPPORT_GNUTLS_SESS_DESC
1640 uschar * s = US gnutls_session_get_desc(session), c;
1642 /* Nikos M suggests we use this by preference. It returns like:
1643 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
1645 For partial back-compat, put a colon after the TLS version, replace the
1646 )-( grouping with __, replace in-group - with _ and append the :keysize. */
1648 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
1650 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
1651 g = string_catn(g, US":", 1);
1652 if (*s) s++; /* now on _ between groups */
1655 for (*++s && ++s; (c = *s) && c != ')'; s++) g = string_catn(g, c == '-' ? US"_" : s, 1);
1656 /* now on ) closing group */
1657 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
1658 /* now on _ between groups */
1660 g = string_catn(g, US":", 1);
1661 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
1662 state->ciphersuite = string_from_gstring(g);
1665 state->ciphersuite = string_sprintf("%s:%s:%d",
1666 gnutls_protocol_get_name(protocol),
1667 gnutls_cipher_suite_get_name(kx, cipher, mac),
1668 (int) gnutls_cipher_get_key_size(cipher) * 8);
1670 /* I don't see a way that spaces could occur, in the current GnuTLS
1671 code base, but it was a concern in the old code and perhaps older GnuTLS
1672 releases did return "TLS 1.0"; play it safe, just in case. */
1674 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
1677 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
1679 tlsp->cipher = state->ciphersuite;
1680 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
1682 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
1684 store_pool = old_pool;
1687 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
1689 if (!cert_list || cert_list_size == 0)
1691 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1692 cert_list, cert_list_size);
1693 if (state->verify_requirement >= VERIFY_REQUIRED)
1694 return tls_error(US"certificate verification failed",
1695 US"no certificate received from peer", state->host, errstr);
1699 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
1701 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
1703 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
1704 if (state->verify_requirement >= VERIFY_REQUIRED)
1705 return tls_error(US"certificate verification not possible, unhandled type",
1706 ctn, state->host, errstr);
1710 #define exim_gnutls_peer_err(Label) \
1712 if (rc != GNUTLS_E_SUCCESS) \
1714 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1715 (Label), gnutls_strerror(rc)); \
1716 if (state->verify_requirement >= VERIFY_REQUIRED) \
1717 return tls_error_gnu((Label), rc, state->host, errstr); \
1722 rc = import_cert(&cert_list[0], &crt);
1723 exim_gnutls_peer_err(US"cert 0");
1725 state->tlsp->peercert = state->peercert = crt;
1728 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
1729 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
1731 exim_gnutls_peer_err(US"getting size for cert DN failed");
1732 return FAIL; /* should not happen */
1734 dn_buf = store_get_perm(sz, TRUE); /* tainted */
1735 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
1736 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1738 state->peerdn = dn_buf;
1741 #undef exim_gnutls_peer_err
1747 /*************************************************
1748 * Verify peer certificate *
1749 *************************************************/
1751 /* Called from both server and client code.
1752 *Should* be using a callback registered with
1753 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1754 the peer information, but that's too new for some OSes.
1757 state exim_gnutls_state_st *
1758 errstr where to put an error message
1761 FALSE if the session should be rejected
1762 TRUE if the cert is okay or we just don't care
1766 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
1771 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
1773 rc = peer_status(state, errstr);
1775 if (state->verify_requirement == VERIFY_NONE)
1778 if (rc != OK || !state->peerdn)
1780 verify = GNUTLS_CERT_INVALID;
1781 *errstr = US"certificate not supplied";
1787 if (state->verify_requirement == VERIFY_DANE && state->host)
1789 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1790 including talking to a DNS resolver. But we want to do that bit ourselves
1791 as the testsuite intercepts and fakes its own DNS environment. */
1796 const gnutls_datum_t * certlist =
1797 gnutls_certificate_get_peers(state->session, &lsize);
1798 int usage = tls_out.tlsa_usage;
1800 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1801 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1802 dane-verification separately so that we know which selector verified;
1803 then we know whether to do name-verification (needed for TA but not EE). */
1805 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
1806 { /* a mixed-usage bundle */
1811 for(nrec = 0; state->dane_data_len[nrec]; ) nrec++;
1814 dd = store_get(nrec * sizeof(uschar *), FALSE);
1815 ddl = store_get(nrec * sizeof(int), FALSE);
1818 if ((rc = dane_state_init(&s, 0)))
1821 for (usage = DANESSL_USAGE_DANE_EE;
1822 usage >= DANESSL_USAGE_DANE_TA; usage--)
1823 { /* take records with this usage */
1824 for (j = i = 0; i < nrec; i++)
1825 if (state->dane_data[i][0] == usage)
1827 dd[j] = state->dane_data[i];
1828 ddl[j++] = state->dane_data_len[i];
1835 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
1838 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
1839 gnutls_certificate_type_get(state->session),
1841 usage == DANESSL_USAGE_DANE_EE
1842 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1846 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
1848 else if (verify == 0) /* verification passed */
1856 if (rc) goto tlsa_prob;
1861 if ( (rc = dane_state_init(&s, 0))
1862 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
1864 || (rc = dane_verify_crt_raw(s, certlist, lsize,
1865 gnutls_certificate_type_get(state->session),
1867 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1868 usage == (1 << DANESSL_USAGE_DANE_EE)
1869 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1878 if (verify != 0) /* verification failed */
1881 (void) dane_verification_status_print(verify, &str, 0);
1882 *errstr = US str.data; /* don't bother to free */
1886 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1887 /* If a TA-mode TLSA record was used for verification we must additionally
1888 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1890 if (usage & (1 << DANESSL_USAGE_DANE_EE))
1893 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1896 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1897 /* Assume that the name on the A-record is the one that should be matching
1898 the cert. An alternate view is that the domain part of the email address
1899 is also permissible. */
1901 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1902 CS state->host->name))
1904 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1909 #endif /*SUPPORT_DANE*/
1911 rc = gnutls_certificate_verify_peers2(state->session, &verify);
1914 /* Handle the result of verification. INVALID is set if any others are. */
1916 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
1918 state->peer_cert_verified = FALSE;
1921 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
1926 if (gnutls_certificate_verification_status_print(verify,
1927 gnutls_certificate_type_get(state->session), &txt, 0)
1928 == GNUTLS_E_SUCCESS)
1930 debug_printf("%s\n", txt.data);
1931 gnutls_free(txt.data);
1935 *errstr = verify & GNUTLS_CERT_REVOKED
1936 ? US"certificate revoked" : US"certificate invalid";
1940 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1941 *errstr, state->peerdn ? state->peerdn : US"<unset>");
1943 if (state->verify_requirement >= VERIFY_REQUIRED)
1946 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1951 /* Client side, check the server's certificate name versus the name on the
1952 A-record for the connection we made. What to do for server side - what name
1953 to use for client? We document that there is no such checking for server
1956 if ( state->exp_tls_verify_cert_hostnames
1957 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1958 CS state->exp_tls_verify_cert_hostnames)
1962 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1963 if (state->verify_requirement >= VERIFY_REQUIRED)
1968 state->peer_cert_verified = TRUE;
1969 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1970 state->peerdn ? state->peerdn : US"<unset>");
1974 state->tlsp->peerdn = state->peerdn;
1979 *errstr = string_sprintf("TLSA record problem: %s",
1980 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
1984 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
1991 /* ------------------------------------------------------------------------ */
1994 /* Logging function which can be registered with
1995 * gnutls_global_set_log_function()
1996 * gnutls_global_set_log_level() 0..9
1998 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2000 exim_gnutls_logger_cb(int level, const char *message)
2002 size_t len = strlen(message);
2005 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2008 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2009 message[len-1] == '\n' ? "" : "\n");
2014 /* Called after client hello, should handle SNI work.
2015 This will always set tls_sni (state->received_sni) if available,
2016 and may trigger presenting different certificates,
2017 if state->trigger_sni_changes is TRUE.
2019 Should be registered with
2020 gnutls_handshake_set_post_client_hello_function()
2022 "This callback must return 0 on success or a gnutls error code to terminate the
2025 For inability to get SNI information, we return 0.
2026 We only return non-zero if re-setup failed.
2027 Only used for server-side TLS.
2031 exim_sni_handling_cb(gnutls_session_t session)
2033 char sni_name[MAX_HOST_LEN];
2034 size_t data_len = MAX_HOST_LEN;
2035 exim_gnutls_state_st *state = &state_server;
2036 unsigned int sni_type;
2038 uschar * dummy_errstr;
2040 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2041 if (rc != GNUTLS_E_SUCCESS)
2044 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2045 debug_printf("TLS: no SNI presented in handshake.\n");
2047 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2048 gnutls_strerror(rc), rc);
2052 if (sni_type != GNUTLS_NAME_DNS)
2054 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2058 /* We now have a UTF-8 string in sni_name */
2059 old_pool = store_pool;
2060 store_pool = POOL_PERM;
2061 state->received_sni = string_copy_taint(US sni_name, TRUE);
2062 store_pool = old_pool;
2064 /* We set this one now so that variable expansions below will work */
2065 state->tlsp->sni = state->received_sni;
2067 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2068 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2070 if (!state->trigger_sni_changes)
2073 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2075 /* If the setup of certs/etc failed before handshake, TLS would not have
2076 been offered. The best we can do now is abort. */
2077 return GNUTLS_E_APPLICATION_ERROR_MIN;
2080 rc = tls_set_remaining_x509(state, &dummy_errstr);
2081 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2088 #if !defined(DISABLE_OCSP)
2091 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
2092 gnutls_datum_t * ocsp_response)
2095 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
2097 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
2099 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
2101 tls_in.ocsp = OCSP_NOT_RESP;
2102 return GNUTLS_E_NO_CERTIFICATE_STATUS;
2105 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
2112 #ifndef DISABLE_EVENT
2114 We use this callback to get observability and detail-level control
2115 for an exim TLS connection (either direction), raising a tls:cert event
2116 for each cert in the chain presented by the peer. Any event
2117 can deny verification.
2119 Return 0 for the handshake to continue or non-zero to terminate.
2123 verify_cb(gnutls_session_t session)
2125 const gnutls_datum_t * cert_list;
2126 unsigned int cert_list_size = 0;
2127 gnutls_x509_crt_t crt;
2130 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2132 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2133 while (cert_list_size--)
2135 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2137 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2138 cert_list_size, gnutls_strerror(rc));
2142 state->tlsp->peercert = crt;
2143 if ((yield = event_raise(state->event_action,
2144 US"tls:cert", string_sprintf("%d", cert_list_size))))
2146 log_write(0, LOG_MAIN,
2147 "SSL verify denied by event-action: depth=%d: %s",
2148 cert_list_size, yield);
2149 return 1; /* reject */
2151 state->tlsp->peercert = NULL;
2161 ddump(gnutls_datum_t * d)
2163 gstring * g = string_get((d->size+1) * 2);
2164 uschar * s = d->data;
2165 for (unsigned i = d->size; i > 0; i--, s++)
2167 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2168 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2174 post_handshake_debug(exim_gnutls_state_st * state)
2176 #ifdef SUPPORT_GNUTLS_SESS_DESC
2177 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2179 #ifdef SUPPORT_GNUTLS_KEYLOG
2180 # ifdef GNUTLS_TLS1_3
2181 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2186 gnutls_datum_t c, s;
2188 /* we only want the client random and the master secret */
2189 gnutls_session_get_random(state->session, &c, &s);
2190 gnutls_session_get_master_secret(state->session, &s);
2193 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2196 debug_printf("To get keying info for TLS1.3 is hard:\n"
2197 " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
2198 " add SSLKEYLOGFILE to keep_environment in the exim config\n"
2199 " run exim as root\n"
2200 " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n");
2205 #ifdef EXPERIMENTAL_TLS_RESUME
2207 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2208 unsigned incoming, const gnutls_datum_t * msg)
2210 DEBUG(D_tls) debug_printf("newticket cb\n");
2211 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2216 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2218 /* Should the server offer session resumption? */
2219 tls_in.resumption = RESUME_SUPPORTED;
2220 if (verify_check_host(&tls_resumption_hosts) == OK)
2223 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2224 an offered resumption is unacceptable. We lose one resumption per ticket
2225 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2226 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2227 least they go out in a single packet. */
2229 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2230 &server_sessticket_key)))
2231 tls_in.resumption |= RESUME_SERVER_TICKET;
2234 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2236 /* Try to tell if we see a ticket request */
2237 gnutls_handshake_set_hook_function(state->session,
2238 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2243 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2245 if (gnutls_session_resumption_requested(state->session))
2247 /* This tells us the client sent a full ticket. We use a
2248 callback on session-ticket request, elsewhere, to tell
2249 if a client asked for a ticket. */
2251 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2252 DEBUG(D_tls) debug_printf("client requested resumption\n");
2254 if (gnutls_session_is_resumed(state->session))
2256 tls_in.resumption |= RESUME_USED;
2257 DEBUG(D_tls) debug_printf("Session resumed\n");
2261 /* ------------------------------------------------------------------------ */
2262 /* Exported functions */
2267 /*************************************************
2268 * Start a TLS session in a server *
2269 *************************************************/
2271 /* This is called when Exim is running as a server, after having received
2272 the STARTTLS command. It must respond to that command, and then negotiate
2276 require_ciphers list of allowed ciphers or NULL
2277 errstr pointer to error string
2279 Returns: OK on success
2280 DEFER for errors before the start of the negotiation
2281 FAIL for errors during the negotiation; the server can't
2286 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2289 exim_gnutls_state_st * state = NULL;
2291 /* Check for previous activation */
2292 if (tls_in.active.sock >= 0)
2294 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2295 smtp_printf("554 Already in TLS\r\n", FALSE);
2299 /* Initialize the library. If it fails, it will already have logged the error
2300 and sent an SMTP response. */
2302 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2304 if ((rc = tls_init(NULL, tls_certificate, tls_privatekey,
2305 NULL, tls_verify_certificates, tls_crl,
2306 require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2308 #ifdef EXPERIMENTAL_TLS_RESUME
2309 tls_server_resume_prehandshake(state);
2312 /* If this is a host for which certificate verification is mandatory or
2313 optional, set up appropriately. */
2315 if (verify_check_host(&tls_verify_hosts) == OK)
2318 debug_printf("TLS: a client certificate will be required.\n");
2319 state->verify_requirement = VERIFY_REQUIRED;
2320 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2322 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2325 debug_printf("TLS: a client certificate will be requested but not required.\n");
2326 state->verify_requirement = VERIFY_OPTIONAL;
2327 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2332 debug_printf("TLS: a client certificate will not be requested.\n");
2333 state->verify_requirement = VERIFY_NONE;
2334 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2337 #ifndef DISABLE_EVENT
2340 state->event_action = event_action;
2341 gnutls_session_set_ptr(state->session, state);
2342 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2346 /* Register SNI handling; always, even if not in tls_certificate, so that the
2347 expansion variable $tls_sni is always available. */
2349 gnutls_handshake_set_post_client_hello_function(state->session,
2350 exim_sni_handling_cb);
2352 /* Set context and tell client to go ahead, except in the case of TLS startup
2353 on connection, where outputting anything now upsets the clients and tends to
2354 make them disconnect. We need to have an explicit fflush() here, to force out
2355 the response. Other smtp_printf() calls do not need it, because in non-TLS
2356 mode, the fflush() happens when smtp_getc() is called. */
2358 if (!state->tlsp->on_connect)
2360 smtp_printf("220 TLS go ahead\r\n", FALSE);
2364 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2365 that the GnuTLS library doesn't.
2366 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2367 to set (and clear down afterwards) up a pull-timeout callback function that does
2368 a select, so we're no better off unless avoiding signals becomes an issue. */
2370 gnutls_transport_set_ptr2(state->session,
2371 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
2372 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
2373 state->fd_in = fileno(smtp_in);
2374 state->fd_out = fileno(smtp_out);
2376 sigalrm_seen = FALSE;
2377 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2379 rc = gnutls_handshake(state->session);
2380 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2383 if (rc != GNUTLS_E_SUCCESS)
2385 /* It seems that, except in the case of a timeout, we have to close the
2386 connection right here; otherwise if the other end is running OpenSSL it hangs
2387 until the server times out. */
2391 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
2392 gnutls_db_remove_session(state->session);
2396 tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr);
2397 (void) gnutls_alert_send_appropriate(state->session, rc);
2398 gnutls_deinit(state->session);
2399 gnutls_certificate_free_credentials(state->x509_cred);
2401 shutdown(state->fd_out, SHUT_WR);
2402 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
2403 (void)fclose(smtp_out);
2404 (void)fclose(smtp_in);
2405 smtp_out = smtp_in = NULL;
2411 #ifdef EXPERIMENTAL_TLS_RESUME
2412 tls_server_resume_posthandshake(state);
2415 DEBUG(D_tls) post_handshake_debug(state);
2417 /* Verify after the fact */
2419 if (!verify_certificate(state, errstr))
2421 if (state->verify_requirement != VERIFY_OPTIONAL)
2423 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
2427 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2431 /* Sets various Exim expansion variables; always safe within server */
2433 extract_exim_vars_from_tls_state(state);
2435 /* TLS has been set up. Adjust the input functions to read via TLS,
2436 and initialize appropriately. */
2438 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2440 receive_getc = tls_getc;
2441 receive_getbuf = tls_getbuf;
2442 receive_get_cache = tls_get_cache;
2443 receive_ungetc = tls_ungetc;
2444 receive_feof = tls_feof;
2445 receive_ferror = tls_ferror;
2446 receive_smtp_buffered = tls_smtp_buffered;
2455 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
2456 smtp_transport_options_block * ob)
2458 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2460 state->exp_tls_verify_cert_hostnames =
2462 string_domain_utf8_to_alabel(host->name, NULL);
2467 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2468 state->exp_tls_verify_cert_hostnames);
2476 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2477 GnuTLS-DANE's preferred format. Hang it on the state str for later
2478 use in DANE verification.
2480 We point at the dnsa data not copy it, so it must remain valid until
2481 after verification is done.*/
2484 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
2488 const char ** dane_data;
2489 int * dane_data_len;
2492 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2493 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2494 ) if (rr->type == T_TLSA) i++;
2496 dane_data = store_get(i * sizeof(uschar *), FALSE);
2497 dane_data_len = store_get(i * sizeof(int), FALSE);
2500 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2501 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2502 ) if (rr->type == T_TLSA && rr->size > 3)
2504 const uschar * p = rr->data;
2505 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
2506 uint8_t usage = p[0], sel = p[1], type = p[2];
2509 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
2511 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
2512 || (sel != 0 && sel != 1)
2517 case 0: /* Full: cannot check at present */
2519 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
2521 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
2526 tls_out.tlsa_usage |= 1<<usage;
2527 dane_data[i] = CS p;
2528 dane_data_len[i++] = rr->size;
2531 if (!i) return FALSE;
2533 dane_data[i] = NULL;
2534 dane_data_len[i] = 0;
2536 state->dane_data = (char * const *)dane_data;
2537 state->dane_data_len = dane_data_len;
2544 #ifdef EXPERIMENTAL_TLS_RESUME
2545 /* On the client, get any stashed session for the given IP from hints db
2546 and apply it to the ssl-connection for attempted resumption. Although
2547 there is a gnutls_session_ticket_enable_client() interface it is
2548 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
2549 by deafult". There seems to be no way to disable them, so even hosts not
2550 enabled by the transport option will be sent a ticket request. We will
2551 however avoid storing and retrieving session information. */
2554 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
2555 host_item * host, smtp_transport_options_block * ob)
2557 tlsp->resumption = RESUME_SUPPORTED;
2558 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
2560 dbdata_tls_session * dt;
2562 open_db dbblock, * dbm_file;
2565 debug_printf("check for resumable session for %s\n", host->address);
2566 tlsp->host_resumable = TRUE;
2567 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2568 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2570 /* Key for the db is the IP. We'd like to filter the retrieved session
2571 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
2573 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
2574 if (!(rc = gnutls_session_set_data(session,
2575 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
2577 DEBUG(D_tls) debug_printf("good session\n");
2578 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2580 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
2581 US gnutls_strerror(rc));
2582 dbfn_close(dbm_file);
2589 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
2591 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
2592 but this flag is not set until the second. TLS 1.3 it's the other way about.
2593 Keep both calls as the session data cannot be extracted before handshake
2596 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
2601 DEBUG(D_tls) debug_printf("server offered session ticket\n");
2602 tlsp->ticket_received = TRUE;
2603 tlsp->resumption |= RESUME_SERVER_TICKET;
2605 if (tlsp->host_resumable)
2606 if (!(rc = gnutls_session_get_data2(session, &tkt)))
2608 open_db dbblock, * dbm_file;
2609 int dlen = sizeof(dbdata_tls_session) + tkt.size;
2610 dbdata_tls_session * dt = store_get(dlen, TRUE);
2612 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
2613 memcpy(dt->session, tkt.data, tkt.size);
2614 gnutls_free(tkt.data);
2616 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
2618 /* key for the db is the IP */
2619 dbfn_delete(dbm_file, host->address);
2620 dbfn_write(dbm_file, host->address, dt, dlen);
2621 dbfn_close(dbm_file);
2624 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
2628 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
2633 /* With a TLS1.3 session, the ticket(s) are not seen until
2634 the first data read is attempted. And there's often two of them.
2635 Pick them up with this callback. We are also called for 1.2
2639 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2640 unsigned incoming, const gnutls_datum_t * msg)
2642 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
2643 tls_support * tlsp = state->tlsp;
2645 DEBUG(D_tls) debug_printf("newticket cb\n");
2647 if (!tlsp->ticket_received)
2648 tls_save_session(tlsp, sess, state->host);
2654 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
2655 tls_support * tlsp, host_item * host,
2656 smtp_transport_options_block * ob)
2658 gnutls_session_set_ptr(state->session, state);
2659 gnutls_handshake_set_hook_function(state->session,
2660 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
2662 tls_retrieve_session(tlsp, state->session, host, ob);
2666 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
2667 tls_support * tlsp, host_item * host)
2669 if (gnutls_session_is_resumed(state->session))
2671 DEBUG(D_tls) debug_printf("Session resumed\n");
2672 tlsp->resumption |= RESUME_USED;
2675 tls_save_session(tlsp, state->session, host);
2677 #endif /* EXPERIMENTAL_TLS_RESUME */
2680 /*************************************************
2681 * Start a TLS session in a client *
2682 *************************************************/
2684 /* Called from the smtp transport after STARTTLS has been accepted.
2687 cctx connection context
2688 conn_args connection details
2689 cookie datum for randomness (not used)
2690 tlsp record details of channel configuration here; must be non-NULL
2691 errstr error string pointer
2693 Returns: TRUE for success with TLS session context set in smtp context,
2698 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
2699 void * cookie ARG_UNUSED,
2700 tls_support * tlsp, uschar ** errstr)
2702 host_item * host = conn_args->host; /* for msgs and option-tests */
2703 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
2704 smtp_transport_options_block * ob = tb
2705 ? (smtp_transport_options_block *)tb->options_block
2706 : &smtp_transport_option_defaults;
2708 exim_gnutls_state_st * state = NULL;
2709 uschar * cipher_list = NULL;
2711 #ifndef DISABLE_OCSP
2713 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
2714 BOOL request_ocsp = require_ocsp ? TRUE
2715 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2718 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
2721 /* If dane is flagged, have either request or require dane for this host, and
2722 a TLSA record found. Therefore, dane verify required. Which implies cert must
2723 be requested and supplied, dane verify must pass, and cert verify irrelevant
2724 (incl. hostnames), and (caller handled) require_tls */
2726 if (conn_args->dane && ob->dane_require_tls_ciphers)
2728 /* not using expand_check_tlsvar because not yet in state */
2729 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2730 &cipher_list, errstr))
2732 cipher_list = cipher_list && *cipher_list
2733 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
2738 cipher_list = ob->tls_require_ciphers;
2740 if (tls_init(host, ob->tls_certificate, ob->tls_privatekey,
2741 ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl,
2742 cipher_list, &state, tlsp, errstr) != OK)
2746 int dh_min_bits = ob->tls_dh_min_bits;
2747 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
2750 debug_printf("WARNING: tls_dh_min_bits far too low,"
2751 " clamping %d up to %d\n",
2752 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
2753 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
2756 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
2757 " acceptable bits to %d\n",
2759 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
2762 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2763 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2764 the specified host patterns if one of them is defined */
2767 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
2770 debug_printf("TLS: server certificate DANE required.\n");
2771 state->verify_requirement = VERIFY_DANE;
2772 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2776 if ( ( state->exp_tls_verify_certificates
2777 && !ob->tls_verify_hosts
2778 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2780 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2783 tls_client_setup_hostname_checks(host, state, ob);
2785 debug_printf("TLS: server certificate verification required.\n");
2786 state->verify_requirement = VERIFY_REQUIRED;
2787 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2789 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2791 tls_client_setup_hostname_checks(host, state, ob);
2793 debug_printf("TLS: server certificate verification optional.\n");
2794 state->verify_requirement = VERIFY_OPTIONAL;
2795 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2800 debug_printf("TLS: server certificate verification not required.\n");
2801 state->verify_requirement = VERIFY_NONE;
2802 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2805 #ifndef DISABLE_OCSP
2806 /* supported since GnuTLS 3.1.3 */
2809 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
2810 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
2811 NULL, 0, NULL)) != OK)
2813 tls_error_gnu(US"cert-status-req", rc, state->host, errstr);
2816 tlsp->ocsp = OCSP_NOT_RESP;
2820 #ifdef EXPERIMENTAL_TLS_RESUME
2821 tls_client_resume_prehandshake(state, tlsp, host, ob);
2824 #ifndef DISABLE_EVENT
2825 if (tb && tb->event_action)
2827 state->event_action = tb->event_action;
2828 gnutls_session_set_ptr(state->session, state);
2829 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2833 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
2834 state->fd_in = cctx->sock;
2835 state->fd_out = cctx->sock;
2837 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
2838 /* There doesn't seem to be a built-in timeout on connection. */
2840 sigalrm_seen = FALSE;
2841 ALARM(ob->command_timeout);
2843 rc = gnutls_handshake(state->session);
2844 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2847 if (rc != GNUTLS_E_SUCCESS)
2851 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
2852 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
2855 tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr);
2859 DEBUG(D_tls) post_handshake_debug(state);
2863 if (!verify_certificate(state, errstr))
2865 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
2869 #ifndef DISABLE_OCSP
2874 gnutls_datum_t stapling;
2875 gnutls_ocsp_resp_t resp;
2876 gnutls_datum_t printed;
2877 if ( (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0
2878 && (rc= gnutls_ocsp_resp_init(&resp)) == 0
2879 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
2880 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0
2883 debug_printf("%.4096s", printed.data);
2884 gnutls_free(printed.data);
2887 (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
2890 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
2892 tlsp->ocsp = OCSP_FAILED;
2893 tls_error(US"certificate status check failed", NULL, state->host, errstr);
2899 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
2900 tlsp->ocsp = OCSP_VFIED;
2905 #ifdef EXPERIMENTAL_TLS_RESUME
2906 tls_client_resume_posthandshake(state, tlsp, host);
2909 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2911 extract_exim_vars_from_tls_state(state);
2913 cctx->tls_ctx = state;
2920 /*************************************************
2921 * Close down a TLS session *
2922 *************************************************/
2924 /* This is also called from within a delivery subprocess forked from the
2925 daemon, to shut down the TLS library, without actually doing a shutdown (which
2926 would tamper with the TLS session in the parent process).
2929 ct_ctx client context pointer, or NULL for the one global server context
2930 shutdown 1 if TLS close-alert is to be sent,
2931 2 if also response to be waited for
2937 tls_close(void * ct_ctx, int shutdown)
2939 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
2940 tls_support * tlsp = state->tlsp;
2942 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
2946 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2947 shutdown > 1 ? " (with response-wait)" : "");
2950 gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
2954 if (!ct_ctx) /* server */
2956 receive_getc = smtp_getc;
2957 receive_getbuf = smtp_getbuf;
2958 receive_get_cache = smtp_get_cache;
2959 receive_ungetc = smtp_ungetc;
2960 receive_feof = smtp_feof;
2961 receive_ferror = smtp_ferror;
2962 receive_smtp_buffered = smtp_buffered;
2965 gnutls_deinit(state->session);
2966 gnutls_certificate_free_credentials(state->x509_cred);
2968 tlsp->active.sock = -1;
2969 tlsp->active.tls_ctx = NULL;
2970 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
2971 tls_channelbinding_b64 = NULL;
2974 if (state->xfer_buffer) store_free(state->xfer_buffer);
2975 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2982 tls_refill(unsigned lim)
2984 exim_gnutls_state_st * state = &state_server;
2987 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2988 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
2990 sigalrm_seen = FALSE;
2991 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2994 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
2995 MIN(ssl_xfer_buffer_size, lim));
2996 while (inbytes == GNUTLS_E_AGAIN);
2998 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3000 if (had_command_timeout) /* set by signal handler */
3001 smtp_command_timeout_exit(); /* does not return */
3002 if (had_command_sigterm)
3003 smtp_command_sigterm_exit();
3004 if (had_data_timeout)
3005 smtp_data_timeout_exit();
3006 if (had_data_sigint)
3007 smtp_data_sigint_exit();
3009 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3010 TLS session has been closed down, not that the socket itself has been closed
3011 down. Revert to non-TLS handling. */
3015 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3016 state->xfer_error = TRUE;
3020 else if (inbytes == 0)
3022 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3023 tls_close(NULL, TLS_NO_SHUTDOWN);
3027 /* Handle genuine errors */
3029 else if (inbytes < 0)
3031 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3032 record_io_error(state, (int) inbytes, US"recv", NULL);
3033 state->xfer_error = TRUE;
3036 #ifndef DISABLE_DKIM
3037 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3039 state->xfer_buffer_hwm = (int) inbytes;
3040 state->xfer_buffer_lwm = 0;
3044 /*************************************************
3045 * TLS version of getc *
3046 *************************************************/
3048 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3049 it refills the buffer via the GnuTLS reading function.
3050 Only used by the server-side TLS.
3052 This feeds DKIM and should be used for all message-body reads.
3054 Arguments: lim Maximum amount to read/buffer
3055 Returns: the next character or EOF
3059 tls_getc(unsigned lim)
3061 exim_gnutls_state_st * state = &state_server;
3063 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3064 if (!tls_refill(lim))
3065 return state->xfer_error ? EOF : smtp_getc(lim);
3067 /* Something in the buffer; return next uschar */
3069 return state->xfer_buffer[state->xfer_buffer_lwm++];
3073 tls_getbuf(unsigned * len)
3075 exim_gnutls_state_st * state = &state_server;
3079 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3080 if (!tls_refill(*len))
3082 if (!state->xfer_error) return smtp_getbuf(len);
3087 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3089 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3090 state->xfer_buffer_lwm += size;
3099 #ifndef DISABLE_DKIM
3100 exim_gnutls_state_st * state = &state_server;
3101 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3103 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3109 tls_could_read(void)
3111 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3112 || gnutls_record_check_pending(state_server.session) > 0;
3118 /*************************************************
3119 * Read bytes from TLS channel *
3120 *************************************************/
3122 /* This does not feed DKIM, so if the caller uses this for reading message body,
3123 then the caller must feed DKIM.
3126 ct_ctx client context pointer, or NULL for the one global server context
3130 Returns: the number of bytes read
3131 -1 after a failed read, including EOF
3135 tls_read(void * ct_ctx, uschar *buff, size_t len)
3137 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3143 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3145 debug_printf("*** PROBABLY A BUG *** " \
3146 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3147 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3150 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n",
3151 state->session, buff, len);
3154 inbytes = gnutls_record_recv(state->session, buff, len);
3155 while (inbytes == GNUTLS_E_AGAIN);
3157 if (inbytes > 0) return inbytes;
3160 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3164 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3165 record_io_error(state, (int)inbytes, US"recv", NULL);
3174 /*************************************************
3175 * Write bytes down TLS channel *
3176 *************************************************/
3180 ct_ctx client context pointer, or NULL for the one global server context
3183 more more data expected soon
3185 Returns: the number of bytes after a successful write,
3186 -1 after a failed write
3190 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3194 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3196 static BOOL corked = FALSE;
3198 if (more && !corked) gnutls_record_cork(state->session);
3201 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3202 buff, left, more ? ", more" : "");
3206 DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n",
3210 outbytes = gnutls_record_send(state->session, buff, left);
3211 while (outbytes == GNUTLS_E_AGAIN);
3213 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
3216 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
3217 record_io_error(state, outbytes, US"send", NULL);
3222 record_io_error(state, 0, US"send", US"TLS channel closed on write");
3233 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
3241 if (!more) (void) gnutls_record_uncork(state->session, 0);
3252 /*************************************************
3253 * Random number generation *
3254 *************************************************/
3256 /* Pseudo-random number generation. The result is not expected to be
3257 cryptographically strong but not so weak that someone will shoot themselves
3258 in the foot using it as a nonce in input in some email header scheme or
3259 whatever weirdness they'll twist this into. The result should handle fork()
3260 and avoid repeating sequences. OpenSSL handles that for us.
3264 Returns a random number in range [0, max-1]
3267 #ifdef HAVE_GNUTLS_RND
3269 vaguely_random_number(int max)
3273 uschar smallbuf[sizeof(r)];
3278 needed_len = sizeof(r);
3279 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3280 asked for a number less than 10. */
3282 for (r = max, i = 0; r; ++i)
3288 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
3291 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
3292 return vaguely_random_number_fallback(max);
3295 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3298 /* We don't particularly care about weighted results; if someone wants
3299 * smooth distribution and cares enough then they should submit a patch then. */
3302 #else /* HAVE_GNUTLS_RND */
3304 vaguely_random_number(int max)
3306 return vaguely_random_number_fallback(max);
3308 #endif /* HAVE_GNUTLS_RND */
3313 /*************************************************
3314 * Let tls_require_ciphers be checked at startup *
3315 *************************************************/
3317 /* The tls_require_ciphers option, if set, must be something which the
3320 Returns: NULL on success, or error message
3324 tls_validate_require_cipher(void)
3327 uschar *expciphers = NULL;
3328 gnutls_priority_t priority_cache;
3330 uschar * dummy_errstr;
3332 #define validate_check_rc(Label) do { \
3333 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3334 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3335 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3337 if (exim_gnutls_base_init_done)
3338 log_write(0, LOG_MAIN|LOG_PANIC,
3339 "already initialised GnuTLS, Exim developer bug");
3341 #ifdef HAVE_GNUTLS_PKCS11
3342 if (!gnutls_allow_auto_pkcs11)
3344 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
3345 validate_check_rc(US"gnutls_pkcs11_init");
3348 rc = gnutls_global_init();
3349 validate_check_rc(US"gnutls_global_init()");
3350 exim_gnutls_base_init_done = TRUE;
3352 if (!(tls_require_ciphers && *tls_require_ciphers))
3353 return_deinit(NULL);
3355 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3357 return_deinit(US"failed to expand tls_require_ciphers");
3359 if (!(expciphers && *expciphers))
3360 return_deinit(NULL);
3363 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3365 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
3366 validate_check_rc(string_sprintf(
3367 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3368 expciphers, errpos - CS expciphers, errpos));
3370 #undef return_deinit
3371 #undef validate_check_rc
3372 gnutls_global_deinit();
3380 /*************************************************
3381 * Report the library versions. *
3382 *************************************************/
3384 /* See a description in tls-openssl.c for an explanation of why this exists.
3386 Arguments: a FILE* to print the results to
3391 tls_version_report(FILE *f)
3393 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
3396 gnutls_check_version(NULL));
3399 #endif /*!MACRO_PREDEF*/
3402 /* End of tls-gnu.c */