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 #if defined(EXPERIMENTAL_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
907 /* Callback for certificate-status, on server. We sent stapled OCSP. */
909 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
910 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
912 DEBUG(D_tls) debug_printf("Sending certificate-status\n");
913 #ifdef SUPPORT_SRV_OCSP_STACK
914 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
915 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
917 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
922 /* Callback for handshake messages, on server */
924 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
925 unsigned incoming, const gnutls_datum_t * msg)
929 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
930 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
931 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
933 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
934 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
935 # ifdef EXPERIMENTAL_TLS_RESUME
936 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
937 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
946 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
948 tls_server_testharness_ocsp_fiddle(void)
950 extern char ** environ;
951 if (environ) for (uschar ** p = USS environ; *p; p++)
952 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
954 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
955 exim_testharness_disable_ocsp_validity_check = TRUE;
960 /*************************************************
961 * Variables re-expanded post-SNI *
962 *************************************************/
964 /* Called from both server and client code, via tls_init(), and also from
965 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
967 We can tell the two apart by state->received_sni being non-NULL in callback.
969 The callback should not call us unless state->trigger_sni_changes is true,
970 which we are responsible for setting on the first pass through.
973 state exim_gnutls_state_st *
974 errstr error string pointer
976 Returns: OK/DEFER/FAIL
980 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
984 const host_item *host = state->host; /* macro should be reconsidered? */
985 uschar *saved_tls_certificate = NULL;
986 uschar *saved_tls_privatekey = NULL;
987 uschar *saved_tls_verify_certificates = NULL;
988 uschar *saved_tls_crl = NULL;
991 /* We check for tls_sni *before* expansion. */
992 if (!host) /* server */
993 if (!state->received_sni)
995 if ( state->tls_certificate
996 && ( Ustrstr(state->tls_certificate, US"tls_sni")
997 || Ustrstr(state->tls_certificate, US"tls_in_sni")
998 || Ustrstr(state->tls_certificate, US"tls_out_sni")
1001 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
1002 state->trigger_sni_changes = TRUE;
1007 /* useful for debugging */
1008 saved_tls_certificate = state->exp_tls_certificate;
1009 saved_tls_privatekey = state->exp_tls_privatekey;
1010 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1011 saved_tls_crl = state->exp_tls_crl;
1014 if ((rc = gnutls_certificate_allocate_credentials(&state->x509_cred)))
1015 return tls_error_gnu(US"gnutls_certificate_allocate_credentials",
1018 #ifdef SUPPORT_SRV_OCSP_STACK
1019 gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2);
1022 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
1023 state members, assuming consistent naming; and expand_check() returns
1024 false if expansion failed, unless expansion was forced to fail. */
1026 /* check if we at least have a certificate, before doing expensive
1029 if (!expand_check_tlsvar(tls_certificate, errstr))
1032 /* certificate is mandatory in server, optional in client */
1034 if ( !state->exp_tls_certificate
1035 || !*state->exp_tls_certificate
1038 return tls_install_selfsign(state, errstr);
1040 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1042 if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr))
1045 /* tls_privatekey is optional, defaulting to same file as certificate */
1047 if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
1049 state->tls_privatekey = state->tls_certificate;
1050 state->exp_tls_privatekey = state->exp_tls_certificate;
1054 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1056 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1057 state->exp_tls_certificate, state->exp_tls_privatekey);
1059 if (state->received_sni)
1060 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1061 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1064 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1068 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
1071 if (!host) /* server */
1073 const uschar * clist = state->exp_tls_certificate;
1074 const uschar * klist = state->exp_tls_privatekey;
1075 const uschar * olist;
1076 int csep = 0, ksep = 0, osep = 0, cnt = 0;
1077 uschar * cfile, * kfile, * ofile;
1079 #ifndef DISABLE_OCSP
1080 if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr))
1085 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1087 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1088 return tls_error(US"cert/key setup: out of keys", NULL, host, errstr);
1089 else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr)))
1093 int gnutls_cert_index = -rc;
1094 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n", gnutls_cert_index, cfile);
1096 /* Set the OCSP stapling server info */
1098 #ifndef DISABLE_OCSP
1101 if (gnutls_buggy_ocsp)
1104 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1106 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1108 DEBUG(D_tls) debug_printf("OCSP response file = %s\n", ofile);
1110 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1111 if (f.running_in_test_harness) tls_server_testharness_ocsp_fiddle();
1113 if (!exim_testharness_disable_ocsp_validity_check)
1115 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1116 state->x509_cred, CCS ofile, gnutls_cert_index,
1117 GNUTLS_X509_FMT_DER)) < 0)
1118 return tls_error_gnu(
1119 US"gnutls_certificate_set_ocsp_status_request_file2",
1122 /* Arrange callbacks for OCSP request observability */
1124 gnutls_handshake_set_hook_function(state->session,
1125 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1128 # elif defined(SUPPORT_SRV_OCSP_STACK)
1129 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1130 state->x509_cred, gnutls_cert_index,
1131 server_ocsp_stapling_cb, ofile)))
1132 return tls_error_gnu(
1133 US"gnutls_certificate_set_ocsp_status_request_function2",
1141 debug_printf("oops; multiple OCSP files not supported\n");
1144 gnutls_certificate_set_ocsp_status_request_function(
1145 state->x509_cred, server_ocsp_stapling_cb, ofile);
1149 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1151 #endif /* DISABLE_OCSP */
1156 if (0 < (rc = tls_add_certfile(state, host,
1157 state->exp_tls_certificate, state->exp_tls_privatekey, errstr)))
1159 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1162 } /* tls_certificate */
1165 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1166 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1167 error message is provided. However, if we just refrain from setting anything up
1168 in that case, certificate verification fails, which seems to be the correct
1171 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1173 if (!expand_check_tlsvar(tls_verify_certificates, errstr))
1175 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1176 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1177 state->exp_tls_verify_certificates = NULL;
1179 if (state->tls_crl && *state->tls_crl)
1180 if (!expand_check_tlsvar(tls_crl, errstr))
1183 if (!(state->exp_tls_verify_certificates &&
1184 *state->exp_tls_verify_certificates))
1187 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1188 /* With no tls_verify_certificates, we ignore tls_crl too */
1195 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1199 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1200 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1201 cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
1205 if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
1207 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
1208 "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
1213 #ifndef SUPPORT_CA_DIR
1214 /* The test suite passes in /dev/null; we could check for that path explicitly,
1215 but who knows if someone has some weird FIFO which always dumps some certs, or
1216 other weirdness. The thing we really want to check is that it's not a
1217 directory, since while OpenSSL supports that, GnuTLS does not.
1218 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1219 if (S_ISDIR(statbuf.st_mode))
1222 debug_printf("verify certificates path is a dir: \"%s\"\n",
1223 state->exp_tls_verify_certificates);
1224 log_write(0, LOG_MAIN|LOG_PANIC,
1225 "tls_verify_certificates \"%s\" is a directory",
1226 state->exp_tls_verify_certificates);
1231 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1232 state->exp_tls_verify_certificates, statbuf.st_size);
1234 if (statbuf.st_size == 0)
1237 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1243 #ifdef SUPPORT_CA_DIR
1244 (statbuf.st_mode & S_IFMT) == S_IFDIR
1246 gnutls_certificate_set_x509_trust_dir(state->x509_cred,
1247 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
1250 gnutls_certificate_set_x509_trust_file(state->x509_cred,
1251 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
1253 #ifdef SUPPORT_CA_DIR
1254 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1255 when using the directory-of-certs config model. */
1257 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1258 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1263 return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr);
1265 debug_printf("Added %d certificate authorities.\n", cert_count);
1267 if (state->tls_crl && *state->tls_crl &&
1268 state->exp_tls_crl && *state->exp_tls_crl)
1270 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
1271 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
1272 CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM)) < 0)
1273 return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file",
1274 cert_count, host, errstr);
1276 DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
1285 /*************************************************
1286 * Set X.509 state variables *
1287 *************************************************/
1289 /* In GnuTLS, the registered cert/key are not replaced by a later
1290 set of a cert/key, so for SNI support we need a whole new x509_cred
1291 structure. Which means various other non-re-expanded pieces of state
1292 need to be re-set in the new struct, so the setting logic is pulled
1296 state exim_gnutls_state_st *
1297 errstr error string pointer
1299 Returns: OK/DEFER/FAIL
1303 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1306 const host_item *host = state->host; /* macro should be reconsidered? */
1308 /* Create D-H parameters, or read them from the cache file. This function does
1309 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1310 client-side params. */
1314 if (!dh_server_params)
1315 if ((rc = init_server_dh(errstr)) != OK) return rc;
1316 gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
1319 /* Link the credentials to the session. */
1321 if ((rc = gnutls_credentials_set(state->session,
1322 GNUTLS_CRD_CERTIFICATE, state->x509_cred)))
1323 return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr);
1328 /*************************************************
1329 * Initialize for GnuTLS *
1330 *************************************************/
1333 #ifndef DISABLE_OCSP
1336 tls_is_buggy_ocsp(void)
1339 uschar maj, mid, mic;
1341 s = CUS gnutls_check_version(NULL);
1345 while (*s && *s != '.') s++;
1346 mid = atoi(CCS ++s);
1353 while (*s && *s != '.') s++;
1354 mic = atoi(CCS ++s);
1355 return mic <= (mid == 3 ? 16 : 3);
1364 /* Called from both server and client code. In the case of a server, errors
1365 before actual TLS negotiation return DEFER.
1368 host connected host, if client; NULL if server
1369 certificate certificate file
1370 privatekey private key file
1371 sni TLS SNI to send, sometimes when client; else NULL
1374 require_ciphers tls_require_ciphers setting
1375 caller_state returned state-info structure
1376 errstr error string pointer
1378 Returns: OK/DEFER/FAIL
1383 const host_item *host,
1384 const uschar *certificate,
1385 const uschar *privatekey,
1389 const uschar *require_ciphers,
1390 exim_gnutls_state_st **caller_state,
1394 exim_gnutls_state_st * state;
1397 const char * errpos;
1400 if (!exim_gnutls_base_init_done)
1402 DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
1404 #ifdef HAVE_GNUTLS_PKCS11
1405 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1406 which loads modules from a config file, which sounds good and may be wanted
1407 by some sysadmin, but also means in common configurations that GNOME keyring
1408 environment variables are used and so breaks for users calling mailq.
1409 To prevent this, we init PKCS11 first, which is the documented approach. */
1410 if (!gnutls_allow_auto_pkcs11)
1411 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
1412 return tls_error_gnu(US"gnutls_pkcs11_init", rc, host, errstr);
1415 if ((rc = gnutls_global_init()))
1416 return tls_error_gnu(US"gnutls_global_init", rc, host, errstr);
1418 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1421 gnutls_global_set_log_function(exim_gnutls_logger_cb);
1422 /* arbitrarily chosen level; bump up to 9 for more */
1423 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
1427 #ifndef DISABLE_OCSP
1428 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
1429 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
1432 exim_gnutls_base_init_done = TRUE;
1437 /* For client-side sessions we allocate a context. This lets us run
1438 several in parallel. */
1439 int old_pool = store_pool;
1440 store_pool = POOL_PERM;
1441 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
1442 store_pool = old_pool;
1444 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1446 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
1447 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
1451 state = &state_server;
1452 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1454 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
1455 rc = gnutls_init(&state->session, GNUTLS_SERVER);
1458 return tls_error_gnu(US"gnutls_init", rc, host, errstr);
1462 state->tls_certificate = certificate;
1463 state->tls_privatekey = privatekey;
1464 state->tls_require_ciphers = require_ciphers;
1465 state->tls_sni = sni;
1466 state->tls_verify_certificates = cas;
1467 state->tls_crl = crl;
1469 /* This handles the variables that might get re-expanded after TLS SNI;
1470 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1473 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1474 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
1476 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1477 requires a new structure afterwards. */
1479 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
1481 /* set SNI in client, only */
1484 if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni, errstr))
1486 if (state->tlsp->sni && *state->tlsp->sni)
1489 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
1490 sz = Ustrlen(state->tlsp->sni);
1491 if ((rc = gnutls_server_name_set(state->session,
1492 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
1493 return tls_error_gnu(US"gnutls_server_name_set", rc, host, errstr);
1496 else if (state->tls_sni)
1497 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
1498 "have an SNI set for a server [%s]\n", state->tls_sni);
1500 /* This is the priority string support,
1501 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1502 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1503 This was backwards incompatible, but means Exim no longer needs to track
1504 all algorithms and provide string forms for them. */
1507 if (state->tls_require_ciphers && *state->tls_require_ciphers)
1509 if (!expand_check_tlsvar(tls_require_ciphers, errstr))
1511 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
1513 p = state->exp_tls_require_ciphers;
1514 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
1519 p = exim_default_gnutls_priority;
1521 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1524 if ((rc = gnutls_priority_init(&state->priority_cache, CCS p, &errpos)))
1525 return tls_error_gnu(string_sprintf(
1526 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1527 p, errpos - CS p, errpos),
1530 if ((rc = gnutls_priority_set(state->session, state->priority_cache)))
1531 return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr);
1533 /* This also sets the server ticket expiration time to the same, and
1534 the STEK rotation time to 3x. */
1536 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
1538 /* Reduce security in favour of increased compatibility, if the admin
1539 decides to make that trade-off. */
1540 if (gnutls_compat_mode)
1542 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1543 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
1544 gnutls_session_enable_compatibility_mode(state->session);
1546 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1550 *caller_state = state;
1556 /*************************************************
1557 * Extract peer information *
1558 *************************************************/
1560 static const uschar *
1561 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
1562 gnutls_mac_algorithm_t mac)
1565 gnutls_kx_algorithm_t kx_i;
1566 gnutls_cipher_algorithm_t cipher_i;
1567 gnutls_mac_algorithm_t mac_i;
1570 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
1572 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
1573 return cipher_stdname(cs_id[0], cs_id[1]);
1579 /* Called from both server and client code.
1580 Only this is allowed to set state->peerdn and state->have_set_peerdn
1581 and we use that to detect double-calls.
1583 NOTE: the state blocks last while the TLS connection is up, which is fine
1584 for logging in the server side, but for the client side, we log after teardown
1585 in src/deliver.c. While the session is up, we can twist about states and
1586 repoint tls_* globals, but those variables used for logging or other variable
1587 expansion that happens _after_ delivery need to have a longer life-time.
1589 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1590 doing this more than once per generation of a state context. We set them in
1591 the state context, and repoint tls_* to them. After the state goes away, the
1592 tls_* copies of the pointers remain valid and client delivery logging is happy.
1594 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1598 state exim_gnutls_state_st *
1599 errstr pointer to error string
1601 Returns: OK/DEFER/FAIL
1605 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
1607 gnutls_session_t session = state->session;
1608 const gnutls_datum_t * cert_list;
1610 unsigned int cert_list_size = 0;
1611 gnutls_protocol_t protocol;
1612 gnutls_cipher_algorithm_t cipher;
1613 gnutls_kx_algorithm_t kx;
1614 gnutls_mac_algorithm_t mac;
1615 gnutls_certificate_type_t ct;
1616 gnutls_x509_crt_t crt;
1620 if (state->have_set_peerdn)
1622 state->have_set_peerdn = TRUE;
1624 state->peerdn = NULL;
1627 cipher = gnutls_cipher_get(session);
1628 protocol = gnutls_protocol_get_version(session);
1629 mac = gnutls_mac_get(session);
1631 #ifdef GNUTLS_TLS1_3
1632 protocol >= GNUTLS_TLS1_3 ? 0 :
1634 gnutls_kx_get(session);
1636 old_pool = store_pool;
1638 tls_support * tlsp = state->tlsp;
1639 store_pool = POOL_PERM;
1641 #ifdef SUPPORT_GNUTLS_SESS_DESC
1644 uschar * s = US gnutls_session_get_desc(session), c;
1646 /* Nikos M suggests we use this by preference. It returns like:
1647 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
1649 For partial back-compat, put a colon after the TLS version, replace the
1650 )-( grouping with __, replace in-group - with _ and append the :keysize. */
1652 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
1654 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
1655 g = string_catn(g, US":", 1);
1656 if (*s) s++; /* now on _ between groups */
1659 for (*++s && ++s; (c = *s) && c != ')'; s++) g = string_catn(g, c == '-' ? US"_" : s, 1);
1660 /* now on ) closing group */
1661 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
1662 /* now on _ between groups */
1664 g = string_catn(g, US":", 1);
1665 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
1666 state->ciphersuite = string_from_gstring(g);
1669 state->ciphersuite = string_sprintf("%s:%s:%d",
1670 gnutls_protocol_get_name(protocol),
1671 gnutls_cipher_suite_get_name(kx, cipher, mac),
1672 (int) gnutls_cipher_get_key_size(cipher) * 8);
1674 /* I don't see a way that spaces could occur, in the current GnuTLS
1675 code base, but it was a concern in the old code and perhaps older GnuTLS
1676 releases did return "TLS 1.0"; play it safe, just in case. */
1678 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
1681 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
1683 tlsp->cipher = state->ciphersuite;
1684 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
1686 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
1688 store_pool = old_pool;
1691 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
1693 if (!cert_list || cert_list_size == 0)
1695 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1696 cert_list, cert_list_size);
1697 if (state->verify_requirement >= VERIFY_REQUIRED)
1698 return tls_error(US"certificate verification failed",
1699 US"no certificate received from peer", state->host, errstr);
1703 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
1705 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
1707 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
1708 if (state->verify_requirement >= VERIFY_REQUIRED)
1709 return tls_error(US"certificate verification not possible, unhandled type",
1710 ctn, state->host, errstr);
1714 #define exim_gnutls_peer_err(Label) \
1716 if (rc != GNUTLS_E_SUCCESS) \
1718 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1719 (Label), gnutls_strerror(rc)); \
1720 if (state->verify_requirement >= VERIFY_REQUIRED) \
1721 return tls_error_gnu((Label), rc, state->host, errstr); \
1726 rc = import_cert(&cert_list[0], &crt);
1727 exim_gnutls_peer_err(US"cert 0");
1729 state->tlsp->peercert = state->peercert = crt;
1732 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
1733 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
1735 exim_gnutls_peer_err(US"getting size for cert DN failed");
1736 return FAIL; /* should not happen */
1738 dn_buf = store_get_perm(sz, TRUE); /* tainted */
1739 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
1740 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1742 state->peerdn = dn_buf;
1745 #undef exim_gnutls_peer_err
1751 /*************************************************
1752 * Verify peer certificate *
1753 *************************************************/
1755 /* Called from both server and client code.
1756 *Should* be using a callback registered with
1757 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1758 the peer information, but that's too new for some OSes.
1761 state exim_gnutls_state_st *
1762 errstr where to put an error message
1765 FALSE if the session should be rejected
1766 TRUE if the cert is okay or we just don't care
1770 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
1775 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
1777 rc = peer_status(state, errstr);
1779 if (state->verify_requirement == VERIFY_NONE)
1782 if (rc != OK || !state->peerdn)
1784 verify = GNUTLS_CERT_INVALID;
1785 *errstr = US"certificate not supplied";
1791 if (state->verify_requirement == VERIFY_DANE && state->host)
1793 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1794 including talking to a DNS resolver. But we want to do that bit ourselves
1795 as the testsuite intercepts and fakes its own DNS environment. */
1800 const gnutls_datum_t * certlist =
1801 gnutls_certificate_get_peers(state->session, &lsize);
1802 int usage = tls_out.tlsa_usage;
1804 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1805 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1806 dane-verification separately so that we know which selector verified;
1807 then we know whether to do name-verification (needed for TA but not EE). */
1809 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
1810 { /* a mixed-usage bundle */
1815 for(nrec = 0; state->dane_data_len[nrec]; ) nrec++;
1818 dd = store_get(nrec * sizeof(uschar *), FALSE);
1819 ddl = store_get(nrec * sizeof(int), FALSE);
1822 if ((rc = dane_state_init(&s, 0)))
1825 for (usage = DANESSL_USAGE_DANE_EE;
1826 usage >= DANESSL_USAGE_DANE_TA; usage--)
1827 { /* take records with this usage */
1828 for (j = i = 0; i < nrec; i++)
1829 if (state->dane_data[i][0] == usage)
1831 dd[j] = state->dane_data[i];
1832 ddl[j++] = state->dane_data_len[i];
1839 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
1842 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
1843 gnutls_certificate_type_get(state->session),
1845 usage == DANESSL_USAGE_DANE_EE
1846 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1850 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
1852 else if (verify == 0) /* verification passed */
1860 if (rc) goto tlsa_prob;
1865 if ( (rc = dane_state_init(&s, 0))
1866 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
1868 || (rc = dane_verify_crt_raw(s, certlist, lsize,
1869 gnutls_certificate_type_get(state->session),
1871 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1872 usage == (1 << DANESSL_USAGE_DANE_EE)
1873 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1882 if (verify != 0) /* verification failed */
1885 (void) dane_verification_status_print(verify, &str, 0);
1886 *errstr = US str.data; /* don't bother to free */
1890 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1891 /* If a TA-mode TLSA record was used for verification we must additionally
1892 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1894 if (usage & (1 << DANESSL_USAGE_DANE_EE))
1897 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1900 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1901 /* Assume that the name on the A-record is the one that should be matching
1902 the cert. An alternate view is that the domain part of the email address
1903 is also permissible. */
1905 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1906 CS state->host->name))
1908 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1913 #endif /*SUPPORT_DANE*/
1915 rc = gnutls_certificate_verify_peers2(state->session, &verify);
1918 /* Handle the result of verification. INVALID is set if any others are. */
1920 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
1922 state->peer_cert_verified = FALSE;
1925 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
1930 if (gnutls_certificate_verification_status_print(verify,
1931 gnutls_certificate_type_get(state->session), &txt, 0)
1932 == GNUTLS_E_SUCCESS)
1934 debug_printf("%s\n", txt.data);
1935 gnutls_free(txt.data);
1939 *errstr = verify & GNUTLS_CERT_REVOKED
1940 ? US"certificate revoked" : US"certificate invalid";
1944 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1945 *errstr, state->peerdn ? state->peerdn : US"<unset>");
1947 if (state->verify_requirement >= VERIFY_REQUIRED)
1950 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1955 /* Client side, check the server's certificate name versus the name on the
1956 A-record for the connection we made. What to do for server side - what name
1957 to use for client? We document that there is no such checking for server
1960 if ( state->exp_tls_verify_cert_hostnames
1961 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1962 CS state->exp_tls_verify_cert_hostnames)
1966 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1967 if (state->verify_requirement >= VERIFY_REQUIRED)
1972 state->peer_cert_verified = TRUE;
1973 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1974 state->peerdn ? state->peerdn : US"<unset>");
1978 state->tlsp->peerdn = state->peerdn;
1983 *errstr = string_sprintf("TLSA record problem: %s",
1984 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
1988 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
1995 /* ------------------------------------------------------------------------ */
1998 /* Logging function which can be registered with
1999 * gnutls_global_set_log_function()
2000 * gnutls_global_set_log_level() 0..9
2002 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2004 exim_gnutls_logger_cb(int level, const char *message)
2006 size_t len = strlen(message);
2009 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2012 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2013 message[len-1] == '\n' ? "" : "\n");
2018 /* Called after client hello, should handle SNI work.
2019 This will always set tls_sni (state->received_sni) if available,
2020 and may trigger presenting different certificates,
2021 if state->trigger_sni_changes is TRUE.
2023 Should be registered with
2024 gnutls_handshake_set_post_client_hello_function()
2026 "This callback must return 0 on success or a gnutls error code to terminate the
2029 For inability to get SNI information, we return 0.
2030 We only return non-zero if re-setup failed.
2031 Only used for server-side TLS.
2035 exim_sni_handling_cb(gnutls_session_t session)
2037 char sni_name[MAX_HOST_LEN];
2038 size_t data_len = MAX_HOST_LEN;
2039 exim_gnutls_state_st *state = &state_server;
2040 unsigned int sni_type;
2042 uschar * dummy_errstr;
2044 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2045 if (rc != GNUTLS_E_SUCCESS)
2048 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2049 debug_printf("TLS: no SNI presented in handshake.\n");
2051 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2052 gnutls_strerror(rc), rc);
2056 if (sni_type != GNUTLS_NAME_DNS)
2058 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2062 /* We now have a UTF-8 string in sni_name */
2063 old_pool = store_pool;
2064 store_pool = POOL_PERM;
2065 state->received_sni = string_copy_taint(US sni_name, TRUE);
2066 store_pool = old_pool;
2068 /* We set this one now so that variable expansions below will work */
2069 state->tlsp->sni = state->received_sni;
2071 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2072 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2074 if (!state->trigger_sni_changes)
2077 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2079 /* If the setup of certs/etc failed before handshake, TLS would not have
2080 been offered. The best we can do now is abort. */
2081 return GNUTLS_E_APPLICATION_ERROR_MIN;
2084 rc = tls_set_remaining_x509(state, &dummy_errstr);
2085 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2092 #if !defined(DISABLE_OCSP)
2095 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
2096 gnutls_datum_t * ocsp_response)
2099 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
2101 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
2103 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
2105 tls_in.ocsp = OCSP_NOT_RESP;
2106 return GNUTLS_E_NO_CERTIFICATE_STATUS;
2109 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
2116 #ifndef DISABLE_EVENT
2118 We use this callback to get observability and detail-level control
2119 for an exim TLS connection (either direction), raising a tls:cert event
2120 for each cert in the chain presented by the peer. Any event
2121 can deny verification.
2123 Return 0 for the handshake to continue or non-zero to terminate.
2127 verify_cb(gnutls_session_t session)
2129 const gnutls_datum_t * cert_list;
2130 unsigned int cert_list_size = 0;
2131 gnutls_x509_crt_t crt;
2134 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2136 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2137 while (cert_list_size--)
2139 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2141 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2142 cert_list_size, gnutls_strerror(rc));
2146 state->tlsp->peercert = crt;
2147 if ((yield = event_raise(state->event_action,
2148 US"tls:cert", string_sprintf("%d", cert_list_size))))
2150 log_write(0, LOG_MAIN,
2151 "SSL verify denied by event-action: depth=%d: %s",
2152 cert_list_size, yield);
2153 return 1; /* reject */
2155 state->tlsp->peercert = NULL;
2165 ddump(gnutls_datum_t * d)
2167 gstring * g = string_get((d->size+1) * 2);
2168 uschar * s = d->data;
2169 for (unsigned i = d->size; i > 0; i--, s++)
2171 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2172 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2178 post_handshake_debug(exim_gnutls_state_st * state)
2180 #ifdef SUPPORT_GNUTLS_SESS_DESC
2181 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2183 #ifdef SUPPORT_GNUTLS_KEYLOG
2184 # ifdef GNUTLS_TLS1_3
2185 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2190 gnutls_datum_t c, s;
2192 /* we only want the client random and the master secret */
2193 gnutls_session_get_random(state->session, &c, &s);
2194 gnutls_session_get_master_secret(state->session, &s);
2197 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2200 debug_printf("To get keying info for TLS1.3 is hard:\n"
2201 " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
2202 " add SSLKEYLOGFILE to keep_environment in the exim config\n"
2203 " run exim as root\n"
2204 " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n");
2209 #ifdef EXPERIMENTAL_TLS_RESUME
2211 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2212 unsigned incoming, const gnutls_datum_t * msg)
2214 DEBUG(D_tls) debug_printf("newticket cb\n");
2215 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2220 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2222 /* Should the server offer session resumption? */
2223 tls_in.resumption = RESUME_SUPPORTED;
2224 if (verify_check_host(&tls_resumption_hosts) == OK)
2227 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2228 an offered resumption is unacceptable. We lose one resumption per ticket
2229 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2230 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2231 least they go out in a single packet. */
2233 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2234 &server_sessticket_key)))
2235 tls_in.resumption |= RESUME_SERVER_TICKET;
2238 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2240 /* Try to tell if we see a ticket request */
2241 gnutls_handshake_set_hook_function(state->session,
2242 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2247 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2249 if (gnutls_session_resumption_requested(state->session))
2251 /* This tells us the client sent a full ticket. We use a
2252 callback on session-ticket request, elsewhere, to tell
2253 if a client asked for a ticket. */
2255 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2256 DEBUG(D_tls) debug_printf("client requested resumption\n");
2258 if (gnutls_session_is_resumed(state->session))
2260 tls_in.resumption |= RESUME_USED;
2261 DEBUG(D_tls) debug_printf("Session resumed\n");
2265 /* ------------------------------------------------------------------------ */
2266 /* Exported functions */
2271 /*************************************************
2272 * Start a TLS session in a server *
2273 *************************************************/
2275 /* This is called when Exim is running as a server, after having received
2276 the STARTTLS command. It must respond to that command, and then negotiate
2280 require_ciphers list of allowed ciphers or NULL
2281 errstr pointer to error string
2283 Returns: OK on success
2284 DEFER for errors before the start of the negotiation
2285 FAIL for errors during the negotiation; the server can't
2290 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2293 exim_gnutls_state_st * state = NULL;
2295 /* Check for previous activation */
2296 if (tls_in.active.sock >= 0)
2298 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2299 smtp_printf("554 Already in TLS\r\n", FALSE);
2303 /* Initialize the library. If it fails, it will already have logged the error
2304 and sent an SMTP response. */
2306 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2308 if ((rc = tls_init(NULL, tls_certificate, tls_privatekey,
2309 NULL, tls_verify_certificates, tls_crl,
2310 require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2312 #ifdef EXPERIMENTAL_TLS_RESUME
2313 tls_server_resume_prehandshake(state);
2316 /* If this is a host for which certificate verification is mandatory or
2317 optional, set up appropriately. */
2319 if (verify_check_host(&tls_verify_hosts) == OK)
2322 debug_printf("TLS: a client certificate will be required.\n");
2323 state->verify_requirement = VERIFY_REQUIRED;
2324 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2326 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2329 debug_printf("TLS: a client certificate will be requested but not required.\n");
2330 state->verify_requirement = VERIFY_OPTIONAL;
2331 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2336 debug_printf("TLS: a client certificate will not be requested.\n");
2337 state->verify_requirement = VERIFY_NONE;
2338 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2341 #ifndef DISABLE_EVENT
2344 state->event_action = event_action;
2345 gnutls_session_set_ptr(state->session, state);
2346 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2350 /* Register SNI handling; always, even if not in tls_certificate, so that the
2351 expansion variable $tls_sni is always available. */
2353 gnutls_handshake_set_post_client_hello_function(state->session,
2354 exim_sni_handling_cb);
2356 /* Set context and tell client to go ahead, except in the case of TLS startup
2357 on connection, where outputting anything now upsets the clients and tends to
2358 make them disconnect. We need to have an explicit fflush() here, to force out
2359 the response. Other smtp_printf() calls do not need it, because in non-TLS
2360 mode, the fflush() happens when smtp_getc() is called. */
2362 if (!state->tlsp->on_connect)
2364 smtp_printf("220 TLS go ahead\r\n", FALSE);
2368 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2369 that the GnuTLS library doesn't.
2370 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2371 to set (and clear down afterwards) up a pull-timeout callback function that does
2372 a select, so we're no better off unless avoiding signals becomes an issue. */
2374 gnutls_transport_set_ptr2(state->session,
2375 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
2376 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
2377 state->fd_in = fileno(smtp_in);
2378 state->fd_out = fileno(smtp_out);
2380 sigalrm_seen = FALSE;
2381 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2383 rc = gnutls_handshake(state->session);
2384 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2387 if (rc != GNUTLS_E_SUCCESS)
2389 /* It seems that, except in the case of a timeout, we have to close the
2390 connection right here; otherwise if the other end is running OpenSSL it hangs
2391 until the server times out. */
2395 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
2396 gnutls_db_remove_session(state->session);
2400 tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr);
2401 (void) gnutls_alert_send_appropriate(state->session, rc);
2402 gnutls_deinit(state->session);
2403 gnutls_certificate_free_credentials(state->x509_cred);
2405 shutdown(state->fd_out, SHUT_WR);
2406 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
2407 (void)fclose(smtp_out);
2408 (void)fclose(smtp_in);
2409 smtp_out = smtp_in = NULL;
2415 #ifdef EXPERIMENTAL_TLS_RESUME
2416 tls_server_resume_posthandshake(state);
2419 DEBUG(D_tls) post_handshake_debug(state);
2421 /* Verify after the fact */
2423 if (!verify_certificate(state, errstr))
2425 if (state->verify_requirement != VERIFY_OPTIONAL)
2427 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
2431 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2435 /* Sets various Exim expansion variables; always safe within server */
2437 extract_exim_vars_from_tls_state(state);
2439 /* TLS has been set up. Adjust the input functions to read via TLS,
2440 and initialize appropriately. */
2442 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2444 receive_getc = tls_getc;
2445 receive_getbuf = tls_getbuf;
2446 receive_get_cache = tls_get_cache;
2447 receive_ungetc = tls_ungetc;
2448 receive_feof = tls_feof;
2449 receive_ferror = tls_ferror;
2450 receive_smtp_buffered = tls_smtp_buffered;
2459 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
2460 smtp_transport_options_block * ob)
2462 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2464 state->exp_tls_verify_cert_hostnames =
2466 string_domain_utf8_to_alabel(host->name, NULL);
2471 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2472 state->exp_tls_verify_cert_hostnames);
2480 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2481 GnuTLS-DANE's preferred format. Hang it on the state str for later
2482 use in DANE verification.
2484 We point at the dnsa data not copy it, so it must remain valid until
2485 after verification is done.*/
2488 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
2492 const char ** dane_data;
2493 int * dane_data_len;
2496 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2497 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2498 ) if (rr->type == T_TLSA) i++;
2500 dane_data = store_get(i * sizeof(uschar *), FALSE);
2501 dane_data_len = store_get(i * sizeof(int), FALSE);
2504 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2505 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2506 ) if (rr->type == T_TLSA && rr->size > 3)
2508 const uschar * p = rr->data;
2509 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
2510 uint8_t usage = p[0], sel = p[1], type = p[2];
2513 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
2515 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
2516 || (sel != 0 && sel != 1)
2521 case 0: /* Full: cannot check at present */
2523 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
2525 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
2530 tls_out.tlsa_usage |= 1<<usage;
2531 dane_data[i] = CS p;
2532 dane_data_len[i++] = rr->size;
2535 if (!i) return FALSE;
2537 dane_data[i] = NULL;
2538 dane_data_len[i] = 0;
2540 state->dane_data = (char * const *)dane_data;
2541 state->dane_data_len = dane_data_len;
2548 #ifdef EXPERIMENTAL_TLS_RESUME
2549 /* On the client, get any stashed session for the given IP from hints db
2550 and apply it to the ssl-connection for attempted resumption. Although
2551 there is a gnutls_session_ticket_enable_client() interface it is
2552 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
2553 by deafult". There seems to be no way to disable them, so even hosts not
2554 enabled by the transport option will be sent a ticket request. We will
2555 however avoid storing and retrieving session information. */
2558 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
2559 host_item * host, smtp_transport_options_block * ob)
2561 tlsp->resumption = RESUME_SUPPORTED;
2562 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
2564 dbdata_tls_session * dt;
2566 open_db dbblock, * dbm_file;
2569 debug_printf("check for resumable session for %s\n", host->address);
2570 tlsp->host_resumable = TRUE;
2571 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2572 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2574 /* Key for the db is the IP. We'd like to filter the retrieved session
2575 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
2577 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
2578 if (!(rc = gnutls_session_set_data(session,
2579 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
2581 DEBUG(D_tls) debug_printf("good session\n");
2582 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2584 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
2585 US gnutls_strerror(rc));
2586 dbfn_close(dbm_file);
2593 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
2595 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
2596 but this flag is not set until the second. TLS 1.3 it's the other way about.
2597 Keep both calls as the session data cannot be extracted before handshake
2600 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
2605 DEBUG(D_tls) debug_printf("server offered session ticket\n");
2606 tlsp->ticket_received = TRUE;
2607 tlsp->resumption |= RESUME_SERVER_TICKET;
2609 if (tlsp->host_resumable)
2610 if (!(rc = gnutls_session_get_data2(session, &tkt)))
2612 open_db dbblock, * dbm_file;
2613 int dlen = sizeof(dbdata_tls_session) + tkt.size;
2614 dbdata_tls_session * dt = store_get(dlen, TRUE);
2616 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
2617 memcpy(dt->session, tkt.data, tkt.size);
2618 gnutls_free(tkt.data);
2620 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
2622 /* key for the db is the IP */
2623 dbfn_delete(dbm_file, host->address);
2624 dbfn_write(dbm_file, host->address, dt, dlen);
2625 dbfn_close(dbm_file);
2628 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
2632 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
2637 /* With a TLS1.3 session, the ticket(s) are not seen until
2638 the first data read is attempted. And there's often two of them.
2639 Pick them up with this callback. We are also called for 1.2
2643 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2644 unsigned incoming, const gnutls_datum_t * msg)
2646 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
2647 tls_support * tlsp = state->tlsp;
2649 DEBUG(D_tls) debug_printf("newticket cb\n");
2651 if (!tlsp->ticket_received)
2652 tls_save_session(tlsp, sess, state->host);
2658 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
2659 tls_support * tlsp, host_item * host,
2660 smtp_transport_options_block * ob)
2662 gnutls_session_set_ptr(state->session, state);
2663 gnutls_handshake_set_hook_function(state->session,
2664 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
2666 tls_retrieve_session(tlsp, state->session, host, ob);
2670 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
2671 tls_support * tlsp, host_item * host)
2673 if (gnutls_session_is_resumed(state->session))
2675 DEBUG(D_tls) debug_printf("Session resumed\n");
2676 tlsp->resumption |= RESUME_USED;
2679 tls_save_session(tlsp, state->session, host);
2681 #endif /* EXPERIMENTAL_TLS_RESUME */
2684 /*************************************************
2685 * Start a TLS session in a client *
2686 *************************************************/
2688 /* Called from the smtp transport after STARTTLS has been accepted.
2691 cctx connection context
2692 conn_args connection details
2693 cookie datum for randomness (not used)
2694 tlsp record details of channel configuration here; must be non-NULL
2695 errstr error string pointer
2697 Returns: TRUE for success with TLS session context set in smtp context,
2702 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
2703 void * cookie ARG_UNUSED,
2704 tls_support * tlsp, uschar ** errstr)
2706 host_item * host = conn_args->host; /* for msgs and option-tests */
2707 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
2708 smtp_transport_options_block * ob = tb
2709 ? (smtp_transport_options_block *)tb->options_block
2710 : &smtp_transport_option_defaults;
2712 exim_gnutls_state_st * state = NULL;
2713 uschar * cipher_list = NULL;
2715 #ifndef DISABLE_OCSP
2717 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
2718 BOOL request_ocsp = require_ocsp ? TRUE
2719 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2722 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
2725 /* If dane is flagged, have either request or require dane for this host, and
2726 a TLSA record found. Therefore, dane verify required. Which implies cert must
2727 be requested and supplied, dane verify must pass, and cert verify irrelevant
2728 (incl. hostnames), and (caller handled) require_tls */
2730 if (conn_args->dane && ob->dane_require_tls_ciphers)
2732 /* not using expand_check_tlsvar because not yet in state */
2733 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2734 &cipher_list, errstr))
2736 cipher_list = cipher_list && *cipher_list
2737 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
2742 cipher_list = ob->tls_require_ciphers;
2744 if (tls_init(host, ob->tls_certificate, ob->tls_privatekey,
2745 ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl,
2746 cipher_list, &state, tlsp, errstr) != OK)
2750 int dh_min_bits = ob->tls_dh_min_bits;
2751 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
2754 debug_printf("WARNING: tls_dh_min_bits far too low,"
2755 " clamping %d up to %d\n",
2756 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
2757 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
2760 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
2761 " acceptable bits to %d\n",
2763 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
2766 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2767 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2768 the specified host patterns if one of them is defined */
2771 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
2774 debug_printf("TLS: server certificate DANE required.\n");
2775 state->verify_requirement = VERIFY_DANE;
2776 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2780 if ( ( state->exp_tls_verify_certificates
2781 && !ob->tls_verify_hosts
2782 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2784 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2787 tls_client_setup_hostname_checks(host, state, ob);
2789 debug_printf("TLS: server certificate verification required.\n");
2790 state->verify_requirement = VERIFY_REQUIRED;
2791 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2793 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2795 tls_client_setup_hostname_checks(host, state, ob);
2797 debug_printf("TLS: server certificate verification optional.\n");
2798 state->verify_requirement = VERIFY_OPTIONAL;
2799 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2804 debug_printf("TLS: server certificate verification not required.\n");
2805 state->verify_requirement = VERIFY_NONE;
2806 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2809 #ifndef DISABLE_OCSP
2810 /* supported since GnuTLS 3.1.3 */
2813 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
2814 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
2815 NULL, 0, NULL)) != OK)
2817 tls_error_gnu(US"cert-status-req", rc, state->host, errstr);
2820 tlsp->ocsp = OCSP_NOT_RESP;
2824 #ifdef EXPERIMENTAL_TLS_RESUME
2825 tls_client_resume_prehandshake(state, tlsp, host, ob);
2828 #ifndef DISABLE_EVENT
2829 if (tb && tb->event_action)
2831 state->event_action = tb->event_action;
2832 gnutls_session_set_ptr(state->session, state);
2833 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2837 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
2838 state->fd_in = cctx->sock;
2839 state->fd_out = cctx->sock;
2841 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
2842 /* There doesn't seem to be a built-in timeout on connection. */
2844 sigalrm_seen = FALSE;
2845 ALARM(ob->command_timeout);
2847 rc = gnutls_handshake(state->session);
2848 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2851 if (rc != GNUTLS_E_SUCCESS)
2855 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
2856 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
2859 tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr);
2863 DEBUG(D_tls) post_handshake_debug(state);
2867 if (!verify_certificate(state, errstr))
2869 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
2873 #ifndef DISABLE_OCSP
2878 gnutls_datum_t stapling;
2879 gnutls_ocsp_resp_t resp;
2880 gnutls_datum_t printed;
2881 if ( (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0
2882 && (rc= gnutls_ocsp_resp_init(&resp)) == 0
2883 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
2884 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0
2887 debug_printf("%.4096s", printed.data);
2888 gnutls_free(printed.data);
2891 (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
2894 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
2896 tlsp->ocsp = OCSP_FAILED;
2897 tls_error(US"certificate status check failed", NULL, state->host, errstr);
2903 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
2904 tlsp->ocsp = OCSP_VFIED;
2909 #ifdef EXPERIMENTAL_TLS_RESUME
2910 tls_client_resume_posthandshake(state, tlsp, host);
2913 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2915 extract_exim_vars_from_tls_state(state);
2917 cctx->tls_ctx = state;
2924 /*************************************************
2925 * Close down a TLS session *
2926 *************************************************/
2928 /* This is also called from within a delivery subprocess forked from the
2929 daemon, to shut down the TLS library, without actually doing a shutdown (which
2930 would tamper with the TLS session in the parent process).
2933 ct_ctx client context pointer, or NULL for the one global server context
2934 shutdown 1 if TLS close-alert is to be sent,
2935 2 if also response to be waited for
2941 tls_close(void * ct_ctx, int shutdown)
2943 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
2944 tls_support * tlsp = state->tlsp;
2946 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
2950 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2951 shutdown > 1 ? " (with response-wait)" : "");
2954 gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
2958 if (!ct_ctx) /* server */
2960 receive_getc = smtp_getc;
2961 receive_getbuf = smtp_getbuf;
2962 receive_get_cache = smtp_get_cache;
2963 receive_ungetc = smtp_ungetc;
2964 receive_feof = smtp_feof;
2965 receive_ferror = smtp_ferror;
2966 receive_smtp_buffered = smtp_buffered;
2969 gnutls_deinit(state->session);
2970 gnutls_certificate_free_credentials(state->x509_cred);
2972 tlsp->active.sock = -1;
2973 tlsp->active.tls_ctx = NULL;
2974 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
2975 tls_channelbinding_b64 = NULL;
2978 if (state->xfer_buffer) store_free(state->xfer_buffer);
2979 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2986 tls_refill(unsigned lim)
2988 exim_gnutls_state_st * state = &state_server;
2991 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2992 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
2994 sigalrm_seen = FALSE;
2995 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2998 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
2999 MIN(ssl_xfer_buffer_size, lim));
3000 while (inbytes == GNUTLS_E_AGAIN);
3002 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3004 if (had_command_timeout) /* set by signal handler */
3005 smtp_command_timeout_exit(); /* does not return */
3006 if (had_command_sigterm)
3007 smtp_command_sigterm_exit();
3008 if (had_data_timeout)
3009 smtp_data_timeout_exit();
3010 if (had_data_sigint)
3011 smtp_data_sigint_exit();
3013 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3014 TLS session has been closed down, not that the socket itself has been closed
3015 down. Revert to non-TLS handling. */
3019 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3020 state->xfer_error = TRUE;
3024 else if (inbytes == 0)
3026 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3027 tls_close(NULL, TLS_NO_SHUTDOWN);
3031 /* Handle genuine errors */
3033 else if (inbytes < 0)
3035 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3036 record_io_error(state, (int) inbytes, US"recv", NULL);
3037 state->xfer_error = TRUE;
3040 #ifndef DISABLE_DKIM
3041 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3043 state->xfer_buffer_hwm = (int) inbytes;
3044 state->xfer_buffer_lwm = 0;
3048 /*************************************************
3049 * TLS version of getc *
3050 *************************************************/
3052 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3053 it refills the buffer via the GnuTLS reading function.
3054 Only used by the server-side TLS.
3056 This feeds DKIM and should be used for all message-body reads.
3058 Arguments: lim Maximum amount to read/buffer
3059 Returns: the next character or EOF
3063 tls_getc(unsigned lim)
3065 exim_gnutls_state_st * state = &state_server;
3067 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3068 if (!tls_refill(lim))
3069 return state->xfer_error ? EOF : smtp_getc(lim);
3071 /* Something in the buffer; return next uschar */
3073 return state->xfer_buffer[state->xfer_buffer_lwm++];
3077 tls_getbuf(unsigned * len)
3079 exim_gnutls_state_st * state = &state_server;
3083 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3084 if (!tls_refill(*len))
3086 if (!state->xfer_error) return smtp_getbuf(len);
3091 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3093 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3094 state->xfer_buffer_lwm += size;
3103 #ifndef DISABLE_DKIM
3104 exim_gnutls_state_st * state = &state_server;
3105 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3107 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3113 tls_could_read(void)
3115 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3116 || gnutls_record_check_pending(state_server.session) > 0;
3122 /*************************************************
3123 * Read bytes from TLS channel *
3124 *************************************************/
3126 /* This does not feed DKIM, so if the caller uses this for reading message body,
3127 then the caller must feed DKIM.
3130 ct_ctx client context pointer, or NULL for the one global server context
3134 Returns: the number of bytes read
3135 -1 after a failed read, including EOF
3139 tls_read(void * ct_ctx, uschar *buff, size_t len)
3141 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3147 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3149 debug_printf("*** PROBABLY A BUG *** " \
3150 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3151 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3154 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n",
3155 state->session, buff, len);
3158 inbytes = gnutls_record_recv(state->session, buff, len);
3159 while (inbytes == GNUTLS_E_AGAIN);
3161 if (inbytes > 0) return inbytes;
3164 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3168 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3169 record_io_error(state, (int)inbytes, US"recv", NULL);
3178 /*************************************************
3179 * Write bytes down TLS channel *
3180 *************************************************/
3184 ct_ctx client context pointer, or NULL for the one global server context
3187 more more data expected soon
3189 Returns: the number of bytes after a successful write,
3190 -1 after a failed write
3194 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3198 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3200 static BOOL corked = FALSE;
3202 if (more && !corked) gnutls_record_cork(state->session);
3205 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3206 buff, left, more ? ", more" : "");
3210 DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n",
3214 outbytes = gnutls_record_send(state->session, buff, left);
3215 while (outbytes == GNUTLS_E_AGAIN);
3217 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
3220 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
3221 record_io_error(state, outbytes, US"send", NULL);
3226 record_io_error(state, 0, US"send", US"TLS channel closed on write");
3237 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
3245 if (!more) (void) gnutls_record_uncork(state->session, 0);
3256 /*************************************************
3257 * Random number generation *
3258 *************************************************/
3260 /* Pseudo-random number generation. The result is not expected to be
3261 cryptographically strong but not so weak that someone will shoot themselves
3262 in the foot using it as a nonce in input in some email header scheme or
3263 whatever weirdness they'll twist this into. The result should handle fork()
3264 and avoid repeating sequences. OpenSSL handles that for us.
3268 Returns a random number in range [0, max-1]
3271 #ifdef HAVE_GNUTLS_RND
3273 vaguely_random_number(int max)
3277 uschar smallbuf[sizeof(r)];
3282 needed_len = sizeof(r);
3283 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3284 asked for a number less than 10. */
3286 for (r = max, i = 0; r; ++i)
3292 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
3295 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
3296 return vaguely_random_number_fallback(max);
3299 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3302 /* We don't particularly care about weighted results; if someone wants
3303 * smooth distribution and cares enough then they should submit a patch then. */
3306 #else /* HAVE_GNUTLS_RND */
3308 vaguely_random_number(int max)
3310 return vaguely_random_number_fallback(max);
3312 #endif /* HAVE_GNUTLS_RND */
3317 /*************************************************
3318 * Let tls_require_ciphers be checked at startup *
3319 *************************************************/
3321 /* The tls_require_ciphers option, if set, must be something which the
3324 Returns: NULL on success, or error message
3328 tls_validate_require_cipher(void)
3331 uschar *expciphers = NULL;
3332 gnutls_priority_t priority_cache;
3334 uschar * dummy_errstr;
3336 #define validate_check_rc(Label) do { \
3337 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3338 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3339 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3341 if (exim_gnutls_base_init_done)
3342 log_write(0, LOG_MAIN|LOG_PANIC,
3343 "already initialised GnuTLS, Exim developer bug");
3345 #ifdef HAVE_GNUTLS_PKCS11
3346 if (!gnutls_allow_auto_pkcs11)
3348 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
3349 validate_check_rc(US"gnutls_pkcs11_init");
3352 rc = gnutls_global_init();
3353 validate_check_rc(US"gnutls_global_init()");
3354 exim_gnutls_base_init_done = TRUE;
3356 if (!(tls_require_ciphers && *tls_require_ciphers))
3357 return_deinit(NULL);
3359 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3361 return_deinit(US"failed to expand tls_require_ciphers");
3363 if (!(expciphers && *expciphers))
3364 return_deinit(NULL);
3367 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3369 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
3370 validate_check_rc(string_sprintf(
3371 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3372 expciphers, errpos - CS expciphers, errpos));
3374 #undef return_deinit
3375 #undef validate_check_rc
3376 gnutls_global_deinit();
3384 /*************************************************
3385 * Report the library versions. *
3386 *************************************************/
3388 /* See a description in tls-openssl.c for an explanation of why this exists.
3390 Arguments: a FILE* to print the results to
3395 tls_version_report(FILE *f)
3397 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
3400 gnutls_check_version(NULL));
3403 #endif /*!MACRO_PREDEF*/
3406 /* End of tls-gnu.c */