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
81 # if GNUTLS_VERSION_NUMBER >= 0x030000
82 # define DANESSL_USAGE_DANE_TA 2
83 # define DANESSL_USAGE_DANE_EE 3
85 # error GnuTLS version too early for DANE
87 # if GNUTLS_VERSION_NUMBER < 0x999999
88 # define GNUTLS_BROKEN_DANE_VALIDATION
93 # include <gnutls/ocsp.h>
96 # include <gnutls/dane.h>
99 #include "tls-cipher-stdname.c"
105 gnutls_global_set_audit_log_function()
108 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
111 /* Local static variables for GnuTLS */
113 /* Values for verify_requirement */
115 enum peer_verify_requirement
116 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
118 /* This holds most state for server or client; with this, we can set up an
119 outbound TLS-enabled connection in an ACL callout, while not stomping all
120 over the TLS variables available for expansion.
122 Some of these correspond to variables in globals.c; those variables will
123 be set to point to content in one of these instances, as appropriate for
124 the stage of the process lifetime.
126 Not handled here: global tls_channelbinding_b64.
129 typedef struct exim_gnutls_state {
130 gnutls_session_t session;
131 gnutls_certificate_credentials_t x509_cred;
132 gnutls_priority_t priority_cache;
133 enum peer_verify_requirement verify_requirement;
136 BOOL peer_cert_verified;
137 BOOL peer_dane_verified;
138 BOOL trigger_sni_changes;
139 BOOL have_set_peerdn;
140 const struct host_item *host; /* NULL if server */
141 gnutls_x509_crt_t peercert;
144 uschar *received_sni;
146 const uschar *tls_certificate;
147 const uschar *tls_privatekey;
148 const uschar *tls_sni; /* client send only, not received */
149 const uschar *tls_verify_certificates;
150 const uschar *tls_crl;
151 const uschar *tls_require_ciphers;
153 uschar *exp_tls_certificate;
154 uschar *exp_tls_privatekey;
155 uschar *exp_tls_verify_certificates;
157 uschar *exp_tls_require_ciphers;
158 const uschar *exp_tls_verify_cert_hostnames;
159 #ifndef DISABLE_EVENT
160 uschar *event_action;
163 char * const * dane_data;
164 const int * dane_data_len;
167 tls_support *tlsp; /* set in tls_init() */
172 BOOL xfer_eof; /*XXX never gets set! */
174 } exim_gnutls_state_st;
176 static const exim_gnutls_state_st exim_gnutls_state_init = {
179 .priority_cache = NULL,
180 .verify_requirement = VERIFY_NONE,
183 .peer_cert_verified = FALSE,
184 .peer_dane_verified = FALSE,
185 .trigger_sni_changes =FALSE,
186 .have_set_peerdn = FALSE,
191 .received_sni = NULL,
193 .tls_certificate = NULL,
194 .tls_privatekey = NULL,
196 .tls_verify_certificates = NULL,
198 .tls_require_ciphers =NULL,
200 .exp_tls_certificate = NULL,
201 .exp_tls_privatekey = NULL,
202 .exp_tls_verify_certificates = NULL,
204 .exp_tls_require_ciphers = NULL,
205 .exp_tls_verify_cert_hostnames = NULL,
206 #ifndef DISABLE_EVENT
207 .event_action = NULL,
212 .xfer_buffer_lwm = 0,
213 .xfer_buffer_hwm = 0,
218 /* Not only do we have our own APIs which don't pass around state, assuming
219 it's held in globals, GnuTLS doesn't appear to let us register callback data
220 for callbacks, or as part of the session, so we have to keep a "this is the
221 context we're currently dealing with" pointer and rely upon being
222 single-threaded to keep from processing data on an inbound TLS connection while
223 talking to another TLS connection for an outbound check. This does mean that
224 there's no way for heart-beats to be responded to, for the duration of the
226 XXX But see gnutls_session_get_ptr()
229 static exim_gnutls_state_st state_server;
231 /* dh_params are initialised once within the lifetime of a process using TLS;
232 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
233 don't want to repeat this. */
235 static gnutls_dh_params_t dh_server_params = NULL;
237 /* No idea how this value was chosen; preserving it. Default is 3600. */
239 static const int ssl_session_timeout = 200;
241 static const char * const exim_default_gnutls_priority = "NORMAL";
243 /* Guard library core initialisation */
245 static BOOL exim_gnutls_base_init_done = FALSE;
248 static BOOL gnutls_buggy_ocsp = FALSE;
252 /* ------------------------------------------------------------------------ */
255 #define MAX_HOST_LEN 255
257 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
258 the library logging; a value less than 0 disables the calls to set up logging
259 callbacks. Possibly GNuTLS also looks for an environment variable
260 "GNUTLS_DEBUG_LEVEL". */
261 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
262 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
265 #ifndef EXIM_CLIENT_DH_MIN_BITS
266 # define EXIM_CLIENT_DH_MIN_BITS 1024
269 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
270 can ask for a bit-strength. Without that, we stick to the constant we had
272 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
273 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
276 #define exim_gnutls_err_check(rc, Label) do { \
277 if ((rc) != GNUTLS_E_SUCCESS) \
278 return tls_error((Label), US gnutls_strerror(rc), host, errstr); \
281 #define expand_check_tlsvar(Varname, errstr) \
282 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
284 #if GNUTLS_VERSION_NUMBER >= 0x020c00
285 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
286 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
287 # define HAVE_GNUTLS_RND
288 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
289 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
290 * isn't available sometimes, so this needs to become a conditional
291 * compilation; the sanest way to deal with this being a problem on
292 * older OSes is to block it in the Local/Makefile with this compiler
294 # ifndef AVOID_GNUTLS_PKCS11
295 # define HAVE_GNUTLS_PKCS11
296 # endif /* AVOID_GNUTLS_PKCS11 */
302 /* ------------------------------------------------------------------------ */
303 /* Callback declarations */
305 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
306 static void exim_gnutls_logger_cb(int level, const char *message);
309 static int exim_sni_handling_cb(gnutls_session_t session);
312 static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
313 gnutls_datum_t * ocsp_response);
318 /* ------------------------------------------------------------------------ */
319 /* Static functions */
321 /*************************************************
323 *************************************************/
325 /* Called from lots of places when errors occur before actually starting to do
326 the TLS handshake, that is, while the session is still in clear. Always returns
327 DEFER for a server and FAIL for a client so that most calls can use "return
328 tls_error(...)" to do this processing and then give an appropriate return. A
329 single function is used for both server and client, because it is called from
330 some shared functions.
333 prefix text to include in the logged error
334 msg additional error string (may be NULL)
335 usually obtained from gnutls_strerror()
336 host NULL if setting up a server;
337 the connected host if setting up a client
338 errstr pointer to returned error string
340 Returns: OK/DEFER/FAIL
344 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
348 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
349 return host ? FAIL : DEFER;
355 /*************************************************
356 * Deal with logging errors during I/O *
357 *************************************************/
359 /* We have to get the identity of the peer from saved data.
362 state the current GnuTLS exim state container
363 rc the GnuTLS error code, or 0 if it's a local error
364 when text identifying read or write
365 text local error text when ec is 0
371 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
376 if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
377 msg = string_sprintf("%s: %s", US gnutls_strerror(rc),
378 US gnutls_alert_get_name(gnutls_alert_get(state->session)));
380 msg = US gnutls_strerror(rc);
382 (void) tls_error(when, msg, state->host, &errstr);
385 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
386 state->host->name, state->host->address, errstr);
389 uschar * conn_info = smtp_get_connection_info();
390 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
391 /* I'd like to get separated H= here, but too hard for now */
392 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
399 /*************************************************
400 * Set various Exim expansion vars *
401 *************************************************/
403 #define exim_gnutls_cert_err(Label) \
406 if (rc != GNUTLS_E_SUCCESS) \
408 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
409 (Label), gnutls_strerror(rc)); \
415 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
419 rc = gnutls_x509_crt_init(crtp);
420 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
422 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
423 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
428 #undef exim_gnutls_cert_err
431 /* We set various Exim global variables from the state, once a session has
432 been established. With TLS callouts, may need to change this to stack
433 variables, or just re-call it with the server state after client callout
436 Make sure anything set here is unset in tls_getc().
440 tls_bits strength indicator
441 tls_certificate_verified bool indicator
442 tls_channelbinding_b64 for some SASL mechanisms
444 tls_peercert pointer to library internal
446 tls_sni a (UTF-8) string
447 tls_ourcert pointer to library internal
450 state the relevant exim_gnutls_state_st *
454 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
456 gnutls_cipher_algorithm_t cipher;
457 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
460 gnutls_datum_t channel;
462 tls_support * tlsp = state->tlsp;
464 tlsp->active.sock = state->fd_out;
465 tlsp->active.tls_ctx = state;
467 cipher = gnutls_cipher_get(state->session);
468 /* returns size in "bytes" */
469 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
471 tlsp->cipher = state->ciphersuite;
473 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
475 tlsp->certificate_verified = state->peer_cert_verified;
477 tlsp->dane_verified = state->peer_dane_verified;
480 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
481 only available for use for authenticators while this TLS session is running. */
483 tls_channelbinding_b64 = NULL;
484 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
487 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
488 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
491 old_pool = store_pool;
492 store_pool = POOL_PERM;
493 tls_channelbinding_b64 = b64encode(CUS channel.data, (int)channel.size);
494 store_pool = old_pool;
495 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
499 /* peercert is set in peer_status() */
500 tlsp->peerdn = state->peerdn;
501 tlsp->sni = state->received_sni;
503 /* record our certificate */
505 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
506 gnutls_x509_crt_t crt;
508 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
515 /*************************************************
516 * Setup up DH parameters *
517 *************************************************/
519 /* Generating the D-H parameters may take a long time. They only need to
520 be re-generated every so often, depending on security policy. What we do is to
521 keep these parameters in a file in the spool directory. If the file does not
522 exist, we generate them. This means that it is easy to cause a regeneration.
524 The new file is written as a temporary file and renamed, so that an incomplete
525 file is never present. If two processes both compute some new parameters, you
526 waste a bit of effort, but it doesn't seem worth messing around with locking to
529 Returns: OK/DEFER/FAIL
533 init_server_dh(uschar ** errstr)
536 unsigned int dh_bits;
538 uschar filename_buf[PATH_MAX];
539 uschar *filename = NULL;
541 uschar *exp_tls_dhparam;
542 BOOL use_file_in_spool = FALSE;
543 BOOL use_fixed_file = FALSE;
544 host_item *host = NULL; /* dummy for macros */
546 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n");
548 rc = gnutls_dh_params_init(&dh_server_params);
549 exim_gnutls_err_check(rc, US"gnutls_dh_params_init");
554 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
557 if (!exp_tls_dhparam)
559 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
560 m.data = US std_dh_prime_default();
561 m.size = Ustrlen(m.data);
563 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
564 use_file_in_spool = TRUE;
565 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
567 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
570 else if (exp_tls_dhparam[0] != '/')
572 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
573 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
574 m.size = Ustrlen(m.data);
578 use_fixed_file = TRUE;
579 filename = exp_tls_dhparam;
584 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
585 exim_gnutls_err_check(rc, US"gnutls_dh_params_import_pkcs3");
586 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
590 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
591 /* If you change this constant, also change dh_param_fn_ext so that we can use a
592 different filename and ensure we have sufficient bits. */
593 dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL);
595 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
597 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
600 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
602 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
606 /* Some clients have hard-coded limits. */
607 if (dh_bits > tls_dh_max_bits)
610 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
612 dh_bits = tls_dh_max_bits;
615 if (use_file_in_spool)
617 if (!string_format(filename_buf, sizeof(filename_buf),
618 "%s/gnutls-params-%d", spool_directory, dh_bits))
619 return tls_error(US"overlong filename", NULL, NULL, errstr);
620 filename = filename_buf;
623 /* Open the cache file for reading and if successful, read it and set up the
626 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
632 if (fstat(fd, &statbuf) < 0) /* EIO */
636 return tls_error(US"TLS cache stat failed", US strerror(saved_errno), NULL, errstr);
638 if (!S_ISREG(statbuf.st_mode))
641 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
643 if (!(fp = fdopen(fd, "rb")))
647 return tls_error(US"fdopen(TLS cache stat fd) failed",
648 US strerror(saved_errno), NULL, errstr);
651 m.size = statbuf.st_size;
652 if (!(m.data = malloc(m.size)))
655 return tls_error(US"malloc failed", US strerror(errno), NULL, errstr);
657 if (!(sz = fread(m.data, m.size, 1, fp)))
662 return tls_error(US"fread failed", US strerror(saved_errno), NULL, errstr);
666 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
668 exim_gnutls_err_check(rc, US"gnutls_dh_params_import_pkcs3");
669 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
672 /* If the file does not exist, fall through to compute new data and cache it.
673 If there was any other opening error, it is serious. */
675 else if (errno == ENOENT)
679 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
682 return tls_error(string_open_failed(errno, "\"%s\" for reading", filename),
685 /* If ret < 0, either the cache file does not exist, or the data it contains
686 is not useful. One particular case of this is when upgrading from an older
687 release of Exim in which the data was stored in a different format. We don't
688 try to be clever and support both formats; we just regenerate new data in this
694 unsigned int dh_bits_gen = dh_bits;
696 if ((PATH_MAX - Ustrlen(filename)) < 10)
697 return tls_error(US"Filename too long to generate replacement",
698 filename, NULL, errstr);
700 temp_fn = string_copy(US"%s.XXXXXXX");
701 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
702 return tls_error(US"Unable to open temp file", US strerror(errno), NULL, errstr);
703 (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */
705 /* GnuTLS overshoots!
706 * If we ask for 2236, we might get 2237 or more.
707 * But there's no way to ask GnuTLS how many bits there really are.
708 * We can ask how many bits were used in a TLS session, but that's it!
709 * The prime itself is hidden behind too much abstraction.
710 * So we ask for less, and proceed on a wing and a prayer.
711 * First attempt, subtracted 3 for 2233 and got 2240.
713 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
715 dh_bits_gen = dh_bits - 10;
717 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
722 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
724 rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen);
725 exim_gnutls_err_check(rc, US"gnutls_dh_params_generate2");
727 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
728 and I confirmed that a NULL call to get the size first is how the GnuTLS
729 sample apps handle this. */
733 rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
735 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
736 exim_gnutls_err_check(rc, US"gnutls_dh_params_export_pkcs3(NULL) sizing");
738 if (!(m.data = malloc(m.size)))
739 return tls_error(US"memory allocation failed", US strerror(errno), NULL, errstr);
741 /* this will return a size 1 less than the allocation size above */
742 rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
744 if (rc != GNUTLS_E_SUCCESS)
747 exim_gnutls_err_check(rc, US"gnutls_dh_params_export_pkcs3() real");
749 m.size = sz; /* shrink by 1, probably */
751 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
754 return tls_error(US"TLS cache write D-H params failed",
755 US strerror(errno), NULL, errstr);
758 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
759 return tls_error(US"TLS cache write D-H params final newline failed",
760 US strerror(errno), NULL, errstr);
762 if ((rc = close(fd)))
763 return tls_error(US"TLS cache write close() failed", US strerror(errno), NULL, errstr);
765 if (Urename(temp_fn, filename) < 0)
766 return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"",
767 temp_fn, filename), US strerror(errno), NULL, errstr);
769 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
772 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
779 /* Create and install a selfsigned certificate, for use in server mode */
782 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
784 gnutls_x509_crt_t cert = NULL;
786 gnutls_x509_privkey_t pkey = NULL;
787 const uschar * where;
790 where = US"initialising pkey";
791 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
793 where = US"initialising cert";
794 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
796 where = US"generating pkey";
797 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
798 #ifdef SUPPORT_PARAM_TO_PK_BITS
799 # ifndef GNUTLS_SEC_PARAM_MEDIUM
800 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
802 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
809 where = US"configuring cert";
811 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
812 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
813 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
814 || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */
815 || (rc = gnutls_x509_crt_set_key(cert, pkey))
817 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
818 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
819 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
820 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
821 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
822 GNUTLS_OID_X520_COMMON_NAME, 0,
823 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
827 where = US"signing cert";
828 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
830 where = US"installing selfsign cert";
832 if ((rc = gnutls_certificate_set_x509_key(state->x509_cred, &cert, 1, pkey)))
838 if (cert) gnutls_x509_crt_deinit(cert);
839 if (pkey) gnutls_x509_privkey_deinit(pkey);
843 rc = tls_error(where, US gnutls_strerror(rc), NULL, errstr);
850 /* Add certificate and key, from files.
853 Zero or negative: good. Negate value for certificate index if < 0.
854 Greater than zero: FAIL or DEFER code.
858 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
859 uschar * certfile, uschar * keyfile, uschar ** errstr)
861 int rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
862 CS certfile, CS keyfile, GNUTLS_X509_FMT_PEM);
865 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
866 US gnutls_strerror(rc), host, errstr);
871 /*************************************************
872 * Variables re-expanded post-SNI *
873 *************************************************/
875 /* Called from both server and client code, via tls_init(), and also from
876 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
878 We can tell the two apart by state->received_sni being non-NULL in callback.
880 The callback should not call us unless state->trigger_sni_changes is true,
881 which we are responsible for setting on the first pass through.
884 state exim_gnutls_state_st *
885 errstr error string pointer
887 Returns: OK/DEFER/FAIL
891 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
895 const host_item *host = state->host; /* macro should be reconsidered? */
896 uschar *saved_tls_certificate = NULL;
897 uschar *saved_tls_privatekey = NULL;
898 uschar *saved_tls_verify_certificates = NULL;
899 uschar *saved_tls_crl = NULL;
902 /* We check for tls_sni *before* expansion. */
903 if (!host) /* server */
904 if (!state->received_sni)
906 if ( state->tls_certificate
907 && ( Ustrstr(state->tls_certificate, US"tls_sni")
908 || Ustrstr(state->tls_certificate, US"tls_in_sni")
909 || Ustrstr(state->tls_certificate, US"tls_out_sni")
912 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
913 state->trigger_sni_changes = TRUE;
918 /* useful for debugging */
919 saved_tls_certificate = state->exp_tls_certificate;
920 saved_tls_privatekey = state->exp_tls_privatekey;
921 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
922 saved_tls_crl = state->exp_tls_crl;
925 rc = gnutls_certificate_allocate_credentials(&state->x509_cred);
926 exim_gnutls_err_check(rc, US"gnutls_certificate_allocate_credentials");
928 #ifdef SUPPORT_SRV_OCSP_STACK
929 gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2);
932 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
933 state members, assuming consistent naming; and expand_check() returns
934 false if expansion failed, unless expansion was forced to fail. */
936 /* check if we at least have a certificate, before doing expensive
939 if (!expand_check_tlsvar(tls_certificate, errstr))
942 /* certificate is mandatory in server, optional in client */
944 if ( !state->exp_tls_certificate
945 || !*state->exp_tls_certificate
948 return tls_install_selfsign(state, errstr);
950 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
952 if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr))
955 /* tls_privatekey is optional, defaulting to same file as certificate */
957 if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
959 state->tls_privatekey = state->tls_certificate;
960 state->exp_tls_privatekey = state->exp_tls_certificate;
964 if (state->exp_tls_certificate && *state->exp_tls_certificate)
966 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
967 state->exp_tls_certificate, state->exp_tls_privatekey);
969 if (state->received_sni)
970 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
971 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
974 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
978 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
981 if (!host) /* server */
983 const uschar * clist = state->exp_tls_certificate;
984 const uschar * klist = state->exp_tls_privatekey;
985 const uschar * olist;
986 int csep = 0, ksep = 0, osep = 0, cnt = 0;
987 uschar * cfile, * kfile, * ofile;
990 if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr))
995 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
997 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
998 return tls_error(US"cert/key setup: out of keys", NULL, host, errstr);
999 else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr)))
1003 int gnutls_cert_index = -rc;
1004 DEBUG(D_tls) debug_printf("TLS: cert/key %s registered\n", cfile);
1006 /* Set the OCSP stapling server info */
1008 #ifndef DISABLE_OCSP
1010 if (gnutls_buggy_ocsp)
1013 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1015 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1017 /* Use the full callback method for stapling just to get
1018 observability. More efficient would be to read the file once only,
1019 if it never changed (due to SNI). Would need restart on file update,
1020 or watch datestamp. */
1022 # ifdef SUPPORT_SRV_OCSP_STACK
1023 rc = gnutls_certificate_set_ocsp_status_request_function2(
1024 state->x509_cred, gnutls_cert_index,
1025 server_ocsp_stapling_cb, ofile);
1027 exim_gnutls_err_check(rc,
1028 US"gnutls_certificate_set_ocsp_status_request_function2");
1033 debug_printf("oops; multiple OCSP files not supported\n");
1036 gnutls_certificate_set_ocsp_status_request_function(
1037 state->x509_cred, server_ocsp_stapling_cb, ofile);
1040 DEBUG(D_tls) debug_printf("OCSP response file = %s\n", ofile);
1043 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1049 if (0 < (rc = tls_add_certfile(state, host,
1050 state->exp_tls_certificate, state->exp_tls_privatekey, errstr)))
1052 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1055 } /* tls_certificate */
1058 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1059 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1060 error message is provided. However, if we just refrain from setting anything up
1061 in that case, certificate verification fails, which seems to be the correct
1064 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1066 if (!expand_check_tlsvar(tls_verify_certificates, errstr))
1068 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1069 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1070 state->exp_tls_verify_certificates = NULL;
1072 if (state->tls_crl && *state->tls_crl)
1073 if (!expand_check_tlsvar(tls_crl, errstr))
1076 if (!(state->exp_tls_verify_certificates &&
1077 *state->exp_tls_verify_certificates))
1080 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1081 /* With no tls_verify_certificates, we ignore tls_crl too */
1088 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1092 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1093 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1094 cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
1098 if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
1100 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
1101 "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
1106 #ifndef SUPPORT_CA_DIR
1107 /* The test suite passes in /dev/null; we could check for that path explicitly,
1108 but who knows if someone has some weird FIFO which always dumps some certs, or
1109 other weirdness. The thing we really want to check is that it's not a
1110 directory, since while OpenSSL supports that, GnuTLS does not.
1111 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1112 if (S_ISDIR(statbuf.st_mode))
1115 debug_printf("verify certificates path is a dir: \"%s\"\n",
1116 state->exp_tls_verify_certificates);
1117 log_write(0, LOG_MAIN|LOG_PANIC,
1118 "tls_verify_certificates \"%s\" is a directory",
1119 state->exp_tls_verify_certificates);
1124 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1125 state->exp_tls_verify_certificates, statbuf.st_size);
1127 if (statbuf.st_size == 0)
1130 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1136 #ifdef SUPPORT_CA_DIR
1137 (statbuf.st_mode & S_IFMT) == S_IFDIR
1139 gnutls_certificate_set_x509_trust_dir(state->x509_cred,
1140 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
1143 gnutls_certificate_set_x509_trust_file(state->x509_cred,
1144 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
1150 exim_gnutls_err_check(rc, US"setting certificate trust");
1152 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count);
1154 if (state->tls_crl && *state->tls_crl &&
1155 state->exp_tls_crl && *state->exp_tls_crl)
1157 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
1158 cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
1159 CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM);
1163 exim_gnutls_err_check(rc, US"gnutls_certificate_set_x509_crl_file");
1165 DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
1174 /*************************************************
1175 * Set X.509 state variables *
1176 *************************************************/
1178 /* In GnuTLS, the registered cert/key are not replaced by a later
1179 set of a cert/key, so for SNI support we need a whole new x509_cred
1180 structure. Which means various other non-re-expanded pieces of state
1181 need to be re-set in the new struct, so the setting logic is pulled
1185 state exim_gnutls_state_st *
1186 errstr error string pointer
1188 Returns: OK/DEFER/FAIL
1192 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1195 const host_item *host = state->host; /* macro should be reconsidered? */
1197 /* Create D-H parameters, or read them from the cache file. This function does
1198 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1199 client-side params. */
1203 if (!dh_server_params)
1205 rc = init_server_dh(errstr);
1206 if (rc != OK) return rc;
1208 gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
1211 /* Link the credentials to the session. */
1213 rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred);
1214 exim_gnutls_err_check(rc, US"gnutls_credentials_set");
1219 /*************************************************
1220 * Initialize for GnuTLS *
1221 *************************************************/
1224 #ifndef DISABLE_OCSP
1227 tls_is_buggy_ocsp(void)
1230 uschar maj, mid, mic;
1232 s = CUS gnutls_check_version(NULL);
1236 while (*s && *s != '.') s++;
1237 mid = atoi(CCS ++s);
1244 while (*s && *s != '.') s++;
1245 mic = atoi(CCS ++s);
1246 return mic <= (mid == 3 ? 16 : 3);
1255 /* Called from both server and client code. In the case of a server, errors
1256 before actual TLS negotiation return DEFER.
1259 host connected host, if client; NULL if server
1260 certificate certificate file
1261 privatekey private key file
1262 sni TLS SNI to send, sometimes when client; else NULL
1265 require_ciphers tls_require_ciphers setting
1266 caller_state returned state-info structure
1267 errstr error string pointer
1269 Returns: OK/DEFER/FAIL
1274 const host_item *host,
1275 const uschar *certificate,
1276 const uschar *privatekey,
1280 const uschar *require_ciphers,
1281 exim_gnutls_state_st **caller_state,
1285 exim_gnutls_state_st *state;
1290 BOOL want_default_priorities;
1292 if (!exim_gnutls_base_init_done)
1294 DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
1296 #ifdef HAVE_GNUTLS_PKCS11
1297 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1298 which loads modules from a config file, which sounds good and may be wanted
1299 by some sysadmin, but also means in common configurations that GNOME keyring
1300 environment variables are used and so breaks for users calling mailq.
1301 To prevent this, we init PKCS11 first, which is the documented approach. */
1302 if (!gnutls_allow_auto_pkcs11)
1304 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
1305 exim_gnutls_err_check(rc, US"gnutls_pkcs11_init");
1309 rc = gnutls_global_init();
1310 exim_gnutls_err_check(rc, US"gnutls_global_init");
1312 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1315 gnutls_global_set_log_function(exim_gnutls_logger_cb);
1316 /* arbitrarily chosen level; bump up to 9 for more */
1317 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
1321 #ifndef DISABLE_OCSP
1322 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
1323 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
1326 exim_gnutls_base_init_done = TRUE;
1331 /* For client-side sessions we allocate a context. This lets us run
1332 several in parallel. */
1333 int old_pool = store_pool;
1334 store_pool = POOL_PERM;
1335 state = store_get(sizeof(exim_gnutls_state_st));
1336 store_pool = old_pool;
1338 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1340 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
1341 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
1345 state = &state_server;
1346 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1348 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
1349 rc = gnutls_init(&state->session, GNUTLS_SERVER);
1351 exim_gnutls_err_check(rc, US"gnutls_init");
1355 state->tls_certificate = certificate;
1356 state->tls_privatekey = privatekey;
1357 state->tls_require_ciphers = require_ciphers;
1358 state->tls_sni = sni;
1359 state->tls_verify_certificates = cas;
1360 state->tls_crl = crl;
1362 /* This handles the variables that might get re-expanded after TLS SNI;
1363 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1366 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1367 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
1369 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1370 requires a new structure afterwards. */
1372 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
1374 /* set SNI in client, only */
1377 if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni, errstr))
1379 if (state->tlsp->sni && *state->tlsp->sni)
1382 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
1383 sz = Ustrlen(state->tlsp->sni);
1384 rc = gnutls_server_name_set(state->session,
1385 GNUTLS_NAME_DNS, state->tlsp->sni, sz);
1386 exim_gnutls_err_check(rc, US"gnutls_server_name_set");
1389 else if (state->tls_sni)
1390 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
1391 "have an SNI set for a server [%s]\n", state->tls_sni);
1393 /* This is the priority string support,
1394 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1395 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1396 This was backwards incompatible, but means Exim no longer needs to track
1397 all algorithms and provide string forms for them. */
1399 want_default_priorities = TRUE;
1401 if (state->tls_require_ciphers && *state->tls_require_ciphers)
1403 if (!expand_check_tlsvar(tls_require_ciphers, errstr))
1405 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
1407 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n",
1408 state->exp_tls_require_ciphers);
1410 rc = gnutls_priority_init(&state->priority_cache,
1411 CS state->exp_tls_require_ciphers, &errpos);
1412 want_default_priorities = FALSE;
1413 p = state->exp_tls_require_ciphers;
1416 if (want_default_priorities)
1419 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n",
1420 exim_default_gnutls_priority);
1421 rc = gnutls_priority_init(&state->priority_cache,
1422 exim_default_gnutls_priority, &errpos);
1423 p = US exim_default_gnutls_priority;
1426 exim_gnutls_err_check(rc, string_sprintf(
1427 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1428 p, errpos - CS p, errpos));
1430 rc = gnutls_priority_set(state->session, state->priority_cache);
1431 exim_gnutls_err_check(rc, US"gnutls_priority_set");
1433 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
1435 /* Reduce security in favour of increased compatibility, if the admin
1436 decides to make that trade-off. */
1437 if (gnutls_compat_mode)
1439 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1440 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
1441 gnutls_session_enable_compatibility_mode(state->session);
1443 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1447 *caller_state = state;
1453 /*************************************************
1454 * Extract peer information *
1455 *************************************************/
1457 static const uschar *
1458 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
1459 gnutls_mac_algorithm_t mac)
1462 gnutls_kx_algorithm_t kx_i;
1463 gnutls_cipher_algorithm_t cipher_i;
1464 gnutls_mac_algorithm_t mac_i;
1467 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
1469 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
1470 return cipher_stdname(cs_id[0], cs_id[1]);
1476 /* Called from both server and client code.
1477 Only this is allowed to set state->peerdn and state->have_set_peerdn
1478 and we use that to detect double-calls.
1480 NOTE: the state blocks last while the TLS connection is up, which is fine
1481 for logging in the server side, but for the client side, we log after teardown
1482 in src/deliver.c. While the session is up, we can twist about states and
1483 repoint tls_* globals, but those variables used for logging or other variable
1484 expansion that happens _after_ delivery need to have a longer life-time.
1486 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1487 doing this more than once per generation of a state context. We set them in
1488 the state context, and repoint tls_* to them. After the state goes away, the
1489 tls_* copies of the pointers remain valid and client delivery logging is happy.
1491 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1495 state exim_gnutls_state_st *
1496 errstr pointer to error string
1498 Returns: OK/DEFER/FAIL
1502 peer_status(exim_gnutls_state_st *state, uschar ** errstr)
1504 const gnutls_datum_t *cert_list;
1506 unsigned int cert_list_size = 0;
1507 gnutls_protocol_t protocol;
1508 gnutls_cipher_algorithm_t cipher;
1509 gnutls_kx_algorithm_t kx;
1510 gnutls_mac_algorithm_t mac;
1511 gnutls_certificate_type_t ct;
1512 gnutls_x509_crt_t crt;
1516 if (state->have_set_peerdn)
1518 state->have_set_peerdn = TRUE;
1520 state->peerdn = NULL;
1523 cipher = gnutls_cipher_get(state->session);
1524 protocol = gnutls_protocol_get_version(state->session);
1525 mac = gnutls_mac_get(state->session);
1526 kx = gnutls_kx_get(state->session);
1528 old_pool = store_pool;
1530 store_pool = POOL_PERM;
1531 state->ciphersuite = string_sprintf("%s:%s:%d",
1532 gnutls_protocol_get_name(protocol),
1533 gnutls_cipher_suite_get_name(kx, cipher, mac),
1534 (int) gnutls_cipher_get_key_size(cipher) * 8);
1536 /* I don't see a way that spaces could occur, in the current GnuTLS
1537 code base, but it was a concern in the old code and perhaps older GnuTLS
1538 releases did return "TLS 1.0"; play it safe, just in case. */
1540 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
1541 state->tlsp->cipher = state->ciphersuite;
1543 state->tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
1545 store_pool = old_pool;
1548 cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size);
1550 if (!cert_list || cert_list_size == 0)
1552 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1553 cert_list, cert_list_size);
1554 if (state->verify_requirement >= VERIFY_REQUIRED)
1555 return tls_error(US"certificate verification failed",
1556 US"no certificate received from peer", state->host, errstr);
1560 ct = gnutls_certificate_type_get(state->session);
1561 if (ct != GNUTLS_CRT_X509)
1563 const uschar *ctn = US gnutls_certificate_type_get_name(ct);
1565 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
1566 if (state->verify_requirement >= VERIFY_REQUIRED)
1567 return tls_error(US"certificate verification not possible, unhandled type",
1568 ctn, state->host, errstr);
1572 #define exim_gnutls_peer_err(Label) \
1574 if (rc != GNUTLS_E_SUCCESS) \
1576 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1577 (Label), gnutls_strerror(rc)); \
1578 if (state->verify_requirement >= VERIFY_REQUIRED) \
1579 return tls_error((Label), US gnutls_strerror(rc), state->host, errstr); \
1584 rc = import_cert(&cert_list[0], &crt);
1585 exim_gnutls_peer_err(US"cert 0");
1587 state->tlsp->peercert = state->peercert = crt;
1590 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
1591 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
1593 exim_gnutls_peer_err(US"getting size for cert DN failed");
1594 return FAIL; /* should not happen */
1596 dn_buf = store_get_perm(sz);
1597 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
1598 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1600 state->peerdn = dn_buf;
1603 #undef exim_gnutls_peer_err
1609 /*************************************************
1610 * Verify peer certificate *
1611 *************************************************/
1613 /* Called from both server and client code.
1614 *Should* be using a callback registered with
1615 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1616 the peer information, but that's too new for some OSes.
1619 state exim_gnutls_state_st *
1620 errstr where to put an error message
1623 FALSE if the session should be rejected
1624 TRUE if the cert is okay or we just don't care
1628 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
1633 if (state->verify_requirement == VERIFY_NONE)
1636 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
1639 if ((rc = peer_status(state, errstr)) != OK)
1641 verify = GNUTLS_CERT_INVALID;
1642 *errstr = US"certificate not supplied";
1648 if (state->verify_requirement == VERIFY_DANE && state->host)
1650 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1651 including talking to a DNS resolver. But we want to do that bit ourselves
1652 as the testsuite intercepts and fakes its own DNS environment. */
1657 const gnutls_datum_t * certlist =
1658 gnutls_certificate_get_peers(state->session, &lsize);
1659 int usage = tls_out.tlsa_usage;
1661 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1662 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1663 dane-verification separately so that we know which selector verified;
1664 then we know whether to do name-verification (needed for TA but not EE). */
1666 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
1667 { /* a mixed-usage bundle */
1672 for(nrec = 0; state->dane_data_len[nrec]; ) nrec++;
1675 dd = store_get(nrec * sizeof(uschar *));
1676 ddl = store_get(nrec * sizeof(int));
1679 if ((rc = dane_state_init(&s, 0)))
1682 for (usage = DANESSL_USAGE_DANE_EE;
1683 usage >= DANESSL_USAGE_DANE_TA; usage--)
1684 { /* take records with this usage */
1685 for (j = i = 0; i < nrec; i++)
1686 if (state->dane_data[i][0] == usage)
1688 dd[j] = state->dane_data[i];
1689 ddl[j++] = state->dane_data_len[i];
1696 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
1699 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
1700 gnutls_certificate_type_get(state->session),
1702 usage == DANESSL_USAGE_DANE_EE
1703 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1707 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
1709 else if (verify == 0) /* verification passed */
1717 if (rc) goto tlsa_prob;
1722 if ( (rc = dane_state_init(&s, 0))
1723 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
1725 || (rc = dane_verify_crt_raw(s, certlist, lsize,
1726 gnutls_certificate_type_get(state->session),
1728 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1729 usage == (1 << DANESSL_USAGE_DANE_EE)
1730 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1739 if (verify != 0) /* verification failed */
1742 (void) dane_verification_status_print(verify, &str, 0);
1743 *errstr = US str.data; /* don't bother to free */
1747 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1748 /* If a TA-mode TLSA record was used for verification we must additionally
1749 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1751 if (usage & (1 << DANESSL_USAGE_DANE_EE))
1754 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1757 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1758 /* Assume that the name on the A-record is the one that should be matching
1759 the cert. An alternate view is that the domain part of the email address
1760 is also permissible. */
1762 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1763 CS state->host->name))
1765 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1770 #endif /*SUPPORT_DANE*/
1772 rc = gnutls_certificate_verify_peers2(state->session, &verify);
1775 /* Handle the result of verification. INVALID is set if any others are. */
1777 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
1779 state->peer_cert_verified = FALSE;
1782 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
1787 if (gnutls_certificate_verification_status_print(verify,
1788 gnutls_certificate_type_get(state->session), &txt, 0)
1789 == GNUTLS_E_SUCCESS)
1791 debug_printf("%s\n", txt.data);
1792 gnutls_free(txt.data);
1796 *errstr = verify & GNUTLS_CERT_REVOKED
1797 ? US"certificate revoked" : US"certificate invalid";
1801 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1802 *errstr, state->peerdn ? state->peerdn : US"<unset>");
1804 if (state->verify_requirement >= VERIFY_REQUIRED)
1807 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1812 /* Client side, check the server's certificate name versus the name on the
1813 A-record for the connection we made. What to do for server side - what name
1814 to use for client? We document that there is no such checking for server
1817 if ( state->exp_tls_verify_cert_hostnames
1818 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1819 CS state->exp_tls_verify_cert_hostnames)
1823 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1824 if (state->verify_requirement >= VERIFY_REQUIRED)
1829 state->peer_cert_verified = TRUE;
1830 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1831 state->peerdn ? state->peerdn : US"<unset>");
1835 state->tlsp->peerdn = state->peerdn;
1840 *errstr = string_sprintf("TLSA record problem: %s",
1841 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
1845 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
1852 /* ------------------------------------------------------------------------ */
1855 /* Logging function which can be registered with
1856 * gnutls_global_set_log_function()
1857 * gnutls_global_set_log_level() 0..9
1859 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1861 exim_gnutls_logger_cb(int level, const char *message)
1863 size_t len = strlen(message);
1866 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
1869 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
1870 message[len-1] == '\n' ? "" : "\n");
1875 /* Called after client hello, should handle SNI work.
1876 This will always set tls_sni (state->received_sni) if available,
1877 and may trigger presenting different certificates,
1878 if state->trigger_sni_changes is TRUE.
1880 Should be registered with
1881 gnutls_handshake_set_post_client_hello_function()
1883 "This callback must return 0 on success or a gnutls error code to terminate the
1886 For inability to get SNI information, we return 0.
1887 We only return non-zero if re-setup failed.
1888 Only used for server-side TLS.
1892 exim_sni_handling_cb(gnutls_session_t session)
1894 char sni_name[MAX_HOST_LEN];
1895 size_t data_len = MAX_HOST_LEN;
1896 exim_gnutls_state_st *state = &state_server;
1897 unsigned int sni_type;
1899 uschar * dummy_errstr;
1901 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
1902 if (rc != GNUTLS_E_SUCCESS)
1905 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
1906 debug_printf("TLS: no SNI presented in handshake.\n");
1908 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
1909 gnutls_strerror(rc), rc);
1914 if (sni_type != GNUTLS_NAME_DNS)
1916 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
1920 /* We now have a UTF-8 string in sni_name */
1921 old_pool = store_pool;
1922 store_pool = POOL_PERM;
1923 state->received_sni = string_copyn(US sni_name, data_len);
1924 store_pool = old_pool;
1926 /* We set this one now so that variable expansions below will work */
1927 state->tlsp->sni = state->received_sni;
1929 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
1930 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
1932 if (!state->trigger_sni_changes)
1935 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
1937 /* If the setup of certs/etc failed before handshake, TLS would not have
1938 been offered. The best we can do now is abort. */
1939 return GNUTLS_E_APPLICATION_ERROR_MIN;
1942 rc = tls_set_remaining_x509(state, &dummy_errstr);
1943 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
1950 #ifndef DISABLE_OCSP
1953 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
1954 gnutls_datum_t * ocsp_response)
1957 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
1959 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
1961 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
1963 tls_in.ocsp = OCSP_NOT_RESP;
1964 return GNUTLS_E_NO_CERTIFICATE_STATUS;
1967 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
1974 #ifndef DISABLE_EVENT
1976 We use this callback to get observability and detail-level control
1977 for an exim TLS connection (either direction), raising a tls:cert event
1978 for each cert in the chain presented by the peer. Any event
1979 can deny verification.
1981 Return 0 for the handshake to continue or non-zero to terminate.
1985 verify_cb(gnutls_session_t session)
1987 const gnutls_datum_t * cert_list;
1988 unsigned int cert_list_size = 0;
1989 gnutls_x509_crt_t crt;
1992 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
1994 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
1995 while (cert_list_size--)
1997 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
1999 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2000 cert_list_size, gnutls_strerror(rc));
2004 state->tlsp->peercert = crt;
2005 if ((yield = event_raise(state->event_action,
2006 US"tls:cert", string_sprintf("%d", cert_list_size))))
2008 log_write(0, LOG_MAIN,
2009 "SSL verify denied by event-action: depth=%d: %s",
2010 cert_list_size, yield);
2011 return 1; /* reject */
2013 state->tlsp->peercert = NULL;
2023 ddump(gnutls_datum_t * d)
2025 gstring * g = string_get((d->size+1) * 2);
2026 uschar * s = d->data;
2027 for (unsigned i = d->size; i > 0; i--, s++)
2029 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2030 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2035 /* ------------------------------------------------------------------------ */
2036 /* Exported functions */
2041 /*************************************************
2042 * Start a TLS session in a server *
2043 *************************************************/
2045 /* This is called when Exim is running as a server, after having received
2046 the STARTTLS command. It must respond to that command, and then negotiate
2050 require_ciphers list of allowed ciphers or NULL
2051 errstr pointer to error string
2053 Returns: OK on success
2054 DEFER for errors before the start of the negotiation
2055 FAIL for errors during the negotiation; the server can't
2060 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2063 exim_gnutls_state_st * state = NULL;
2065 /* Check for previous activation */
2066 if (tls_in.active.sock >= 0)
2068 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2069 smtp_printf("554 Already in TLS\r\n", FALSE);
2073 /* Initialize the library. If it fails, it will already have logged the error
2074 and sent an SMTP response. */
2076 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2078 if ((rc = tls_init(NULL, tls_certificate, tls_privatekey,
2079 NULL, tls_verify_certificates, tls_crl,
2080 require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2082 /* If this is a host for which certificate verification is mandatory or
2083 optional, set up appropriately. */
2085 if (verify_check_host(&tls_verify_hosts) == OK)
2088 debug_printf("TLS: a client certificate will be required.\n");
2089 state->verify_requirement = VERIFY_REQUIRED;
2090 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2092 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2095 debug_printf("TLS: a client certificate will be requested but not required.\n");
2096 state->verify_requirement = VERIFY_OPTIONAL;
2097 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2102 debug_printf("TLS: a client certificate will not be requested.\n");
2103 state->verify_requirement = VERIFY_NONE;
2104 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2107 #ifndef DISABLE_EVENT
2110 state->event_action = event_action;
2111 gnutls_session_set_ptr(state->session, state);
2112 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2116 /* Register SNI handling; always, even if not in tls_certificate, so that the
2117 expansion variable $tls_sni is always available. */
2119 gnutls_handshake_set_post_client_hello_function(state->session,
2120 exim_sni_handling_cb);
2122 /* Set context and tell client to go ahead, except in the case of TLS startup
2123 on connection, where outputting anything now upsets the clients and tends to
2124 make them disconnect. We need to have an explicit fflush() here, to force out
2125 the response. Other smtp_printf() calls do not need it, because in non-TLS
2126 mode, the fflush() happens when smtp_getc() is called. */
2128 if (!state->tlsp->on_connect)
2130 smtp_printf("220 TLS go ahead\r\n", FALSE);
2134 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2135 that the GnuTLS library doesn't.
2136 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2137 to set (and clear down afterwards) up a pull-timeout callback function that does
2138 a select, so we're no better off unless avoiding signals becomes an issue. */
2140 gnutls_transport_set_ptr2(state->session,
2141 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
2142 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
2143 state->fd_in = fileno(smtp_in);
2144 state->fd_out = fileno(smtp_out);
2146 sigalrm_seen = FALSE;
2147 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2149 rc = gnutls_handshake(state->session);
2150 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2153 if (rc != GNUTLS_E_SUCCESS)
2155 /* It seems that, except in the case of a timeout, we have to close the
2156 connection right here; otherwise if the other end is running OpenSSL it hangs
2157 until the server times out. */
2161 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
2162 gnutls_db_remove_session(state->session);
2166 tls_error(US"gnutls_handshake", US gnutls_strerror(rc), NULL, errstr);
2167 (void) gnutls_alert_send_appropriate(state->session, rc);
2168 gnutls_deinit(state->session);
2169 gnutls_certificate_free_credentials(state->x509_cred);
2171 shutdown(state->fd_out, SHUT_WR);
2172 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
2173 (void)fclose(smtp_out);
2174 (void)fclose(smtp_in);
2175 smtp_out = smtp_in = NULL;
2183 debug_printf("gnutls_handshake was successful\n");
2184 #ifdef SUPPORT_GNUTLS_SESS_DESC
2185 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2187 #ifdef SUPPORT_GNUTLS_KEYLOG
2189 gnutls_datum_t c, s;
2191 gnutls_session_get_random(state->session, &c, &s);
2192 gnutls_session_get_master_secret(state->session, &s);
2195 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2200 /* Verify after the fact */
2202 if (!verify_certificate(state, errstr))
2204 if (state->verify_requirement != VERIFY_OPTIONAL)
2206 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
2210 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2214 /* Figure out peer DN, and if authenticated, etc. */
2216 if ((rc = peer_status(state, NULL)) != OK) return rc;
2218 /* Sets various Exim expansion variables; always safe within server */
2220 extract_exim_vars_from_tls_state(state);
2222 /* TLS has been set up. Adjust the input functions to read via TLS,
2223 and initialize appropriately. */
2225 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2227 receive_getc = tls_getc;
2228 receive_getbuf = tls_getbuf;
2229 receive_get_cache = tls_get_cache;
2230 receive_ungetc = tls_ungetc;
2231 receive_feof = tls_feof;
2232 receive_ferror = tls_ferror;
2233 receive_smtp_buffered = tls_smtp_buffered;
2242 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
2243 smtp_transport_options_block * ob)
2245 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2247 state->exp_tls_verify_cert_hostnames =
2249 string_domain_utf8_to_alabel(host->name, NULL);
2254 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2255 state->exp_tls_verify_cert_hostnames);
2263 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2264 GnuTLS-DANE's preferred format. Hang it on the state str for later
2265 use in DANE verification.
2267 We point at the dnsa data not copy it, so it must remain valid until
2268 after verification is done.*/
2271 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
2275 const char ** dane_data;
2276 int * dane_data_len;
2279 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2280 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2281 ) if (rr->type == T_TLSA) i++;
2283 dane_data = store_get(i * sizeof(uschar *));
2284 dane_data_len = store_get(i * sizeof(int));
2287 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2288 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2289 ) if (rr->type == T_TLSA && rr->size > 3)
2291 const uschar * p = rr->data;
2292 uint8_t usage = p[0], sel = p[1], type = p[2];
2295 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
2297 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
2298 || (sel != 0 && sel != 1)
2303 case 0: /* Full: cannot check at present */
2305 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
2307 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
2312 tls_out.tlsa_usage |= 1<<usage;
2313 dane_data[i] = CS p;
2314 dane_data_len[i++] = rr->size;
2317 if (!i) return FALSE;
2319 dane_data[i] = NULL;
2320 dane_data_len[i] = 0;
2322 state->dane_data = (char * const *)dane_data;
2323 state->dane_data_len = dane_data_len;
2330 /*************************************************
2331 * Start a TLS session in a client *
2332 *************************************************/
2334 /* Called from the smtp transport after STARTTLS has been accepted.
2337 fd the fd of the connection
2338 host connected host (for messages and option-tests)
2339 addr the first address (not used)
2340 tb transport (always smtp)
2341 tlsa_dnsa non-NULL, either request or require dane for this host, and
2342 a TLSA record found. Therefore, dane verify required.
2343 Which implies cert must be requested and supplied, dane
2344 verify must pass, and cert verify irrelevant (incl.
2345 hostnames), and (caller handled) require_tls
2346 tlsp record details of channel configuration
2347 errstr error string pointer
2349 Returns: Pointer to TLS session context, or NULL on error
2353 tls_client_start(int fd, host_item *host,
2354 address_item *addr ARG_UNUSED,
2355 transport_instance * tb,
2357 dns_answer * tlsa_dnsa,
2359 tls_support * tlsp, uschar ** errstr)
2361 smtp_transport_options_block *ob = tb
2362 ? (smtp_transport_options_block *)tb->options_block
2363 : &smtp_transport_option_defaults;
2365 exim_gnutls_state_st * state = NULL;
2366 uschar *cipher_list = NULL;
2368 #ifndef DISABLE_OCSP
2370 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
2371 BOOL request_ocsp = require_ocsp ? TRUE
2372 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2375 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd);
2378 if (tlsa_dnsa && ob->dane_require_tls_ciphers)
2380 /* not using expand_check_tlsvar because not yet in state */
2381 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2382 &cipher_list, errstr))
2384 cipher_list = cipher_list && *cipher_list
2385 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
2390 cipher_list = ob->tls_require_ciphers;
2392 if (tls_init(host, ob->tls_certificate, ob->tls_privatekey,
2393 ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl,
2394 cipher_list, &state, tlsp, errstr) != OK)
2398 int dh_min_bits = ob->tls_dh_min_bits;
2399 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
2402 debug_printf("WARNING: tls_dh_min_bits far too low,"
2403 " clamping %d up to %d\n",
2404 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
2405 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
2408 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
2409 " acceptable bits to %d\n",
2411 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
2414 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2415 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2416 the specified host patterns if one of them is defined */
2419 if (tlsa_dnsa && dane_tlsa_load(state, tlsa_dnsa))
2422 debug_printf("TLS: server certificate DANE required.\n");
2423 state->verify_requirement = VERIFY_DANE;
2424 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2428 if ( ( state->exp_tls_verify_certificates
2429 && !ob->tls_verify_hosts
2430 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2432 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2435 tls_client_setup_hostname_checks(host, state, ob);
2437 debug_printf("TLS: server certificate verification required.\n");
2438 state->verify_requirement = VERIFY_REQUIRED;
2439 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2441 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2443 tls_client_setup_hostname_checks(host, state, ob);
2445 debug_printf("TLS: server certificate verification optional.\n");
2446 state->verify_requirement = VERIFY_OPTIONAL;
2447 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2452 debug_printf("TLS: server certificate verification not required.\n");
2453 state->verify_requirement = VERIFY_NONE;
2454 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2457 #ifndef DISABLE_OCSP
2458 /* supported since GnuTLS 3.1.3 */
2461 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
2462 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
2463 NULL, 0, NULL)) != OK)
2465 tls_error(US"cert-status-req", US gnutls_strerror(rc), state->host, errstr);
2468 tlsp->ocsp = OCSP_NOT_RESP;
2472 #ifndef DISABLE_EVENT
2473 if (tb && tb->event_action)
2475 state->event_action = tb->event_action;
2476 gnutls_session_set_ptr(state->session, state);
2477 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2481 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) fd);
2485 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
2486 /* There doesn't seem to be a built-in timeout on connection. */
2488 sigalrm_seen = FALSE;
2489 ALARM(ob->command_timeout);
2491 rc = gnutls_handshake(state->session);
2492 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2495 if (rc != GNUTLS_E_SUCCESS)
2499 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
2500 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
2503 tls_error(US"gnutls_handshake", US gnutls_strerror(rc), state->host, errstr);
2509 debug_printf("gnutls_handshake was successful\n");
2510 #ifdef SUPPORT_GNUTLS_SESS_DESC
2511 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2513 #ifdef SUPPORT_GNUTLS_KEYLOG
2515 gnutls_datum_t c, s;
2517 gnutls_session_get_random(state->session, &c, &s);
2518 gnutls_session_get_master_secret(state->session, &s);
2521 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2528 if (!verify_certificate(state, errstr))
2530 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
2534 #ifndef DISABLE_OCSP
2539 gnutls_datum_t stapling;
2540 gnutls_ocsp_resp_t resp;
2541 gnutls_datum_t printed;
2542 if ( (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0
2543 && (rc= gnutls_ocsp_resp_init(&resp)) == 0
2544 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
2545 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0
2548 debug_printf("%.4096s", printed.data);
2549 gnutls_free(printed.data);
2552 (void) tls_error(US"ocsp decode", US gnutls_strerror(rc), state->host, errstr);
2555 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
2557 tlsp->ocsp = OCSP_FAILED;
2558 tls_error(US"certificate status check failed", NULL, state->host, errstr);
2561 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
2562 tlsp->ocsp = OCSP_VFIED;
2566 /* Figure out peer DN, and if authenticated, etc. */
2568 if (peer_status(state, errstr) != OK)
2571 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2573 extract_exim_vars_from_tls_state(state);
2581 /*************************************************
2582 * Close down a TLS session *
2583 *************************************************/
2585 /* This is also called from within a delivery subprocess forked from the
2586 daemon, to shut down the TLS library, without actually doing a shutdown (which
2587 would tamper with the TLS session in the parent process).
2590 ct_ctx client context pointer, or NULL for the one global server context
2591 shutdown 1 if TLS close-alert is to be sent,
2592 2 if also response to be waited for
2598 tls_close(void * ct_ctx, int shutdown)
2600 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
2602 if (!state->tlsp || state->tlsp->active.sock < 0) return; /* TLS was not active */
2606 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
2607 shutdown > 1 ? " (with response-wait)" : "");
2610 gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
2614 gnutls_deinit(state->session);
2615 gnutls_certificate_free_credentials(state->x509_cred);
2618 state->tlsp->active.sock = -1;
2619 state->tlsp->active.tls_ctx = NULL;
2620 if (state->xfer_buffer) store_free(state->xfer_buffer);
2621 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
2628 tls_refill(unsigned lim)
2630 exim_gnutls_state_st * state = &state_server;
2633 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2634 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
2636 sigalrm_seen = FALSE;
2637 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2640 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
2641 MIN(ssl_xfer_buffer_size, lim));
2642 while (inbytes == GNUTLS_E_AGAIN);
2644 if (smtp_receive_timeout > 0) ALARM_CLR(0);
2646 if (had_command_timeout) /* set by signal handler */
2647 smtp_command_timeout_exit(); /* does not return */
2648 if (had_command_sigterm)
2649 smtp_command_sigterm_exit();
2650 if (had_data_timeout)
2651 smtp_data_timeout_exit();
2652 if (had_data_sigint)
2653 smtp_data_sigint_exit();
2655 /* Timeouts do not get this far. A zero-byte return appears to mean that the
2656 TLS session has been closed down, not that the socket itself has been closed
2657 down. Revert to non-TLS handling. */
2661 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
2662 state->xfer_error = TRUE;
2666 else if (inbytes == 0)
2668 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
2670 receive_getc = smtp_getc;
2671 receive_getbuf = smtp_getbuf;
2672 receive_get_cache = smtp_get_cache;
2673 receive_ungetc = smtp_ungetc;
2674 receive_feof = smtp_feof;
2675 receive_ferror = smtp_ferror;
2676 receive_smtp_buffered = smtp_buffered;
2678 gnutls_deinit(state->session);
2679 gnutls_certificate_free_credentials(state->x509_cred);
2681 state->session = NULL;
2682 state->tlsp->active.sock = -1;
2683 state->tlsp->active.tls_ctx = NULL;
2684 state->tlsp->bits = 0;
2685 state->tlsp->certificate_verified = FALSE;
2686 tls_channelbinding_b64 = NULL;
2687 state->tlsp->cipher = NULL;
2688 state->tlsp->peercert = NULL;
2689 state->tlsp->peerdn = NULL;
2694 /* Handle genuine errors */
2696 else if (inbytes < 0)
2698 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv(\n", __FUNCTION__);
2699 record_io_error(state, (int) inbytes, US"recv", NULL);
2700 state->xfer_error = TRUE;
2703 #ifndef DISABLE_DKIM
2704 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
2706 state->xfer_buffer_hwm = (int) inbytes;
2707 state->xfer_buffer_lwm = 0;
2711 /*************************************************
2712 * TLS version of getc *
2713 *************************************************/
2715 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2716 it refills the buffer via the GnuTLS reading function.
2717 Only used by the server-side TLS.
2719 This feeds DKIM and should be used for all message-body reads.
2721 Arguments: lim Maximum amount to read/buffer
2722 Returns: the next character or EOF
2726 tls_getc(unsigned lim)
2728 exim_gnutls_state_st * state = &state_server;
2730 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
2731 if (!tls_refill(lim))
2732 return state->xfer_error ? EOF : smtp_getc(lim);
2734 /* Something in the buffer; return next uschar */
2736 return state->xfer_buffer[state->xfer_buffer_lwm++];
2740 tls_getbuf(unsigned * len)
2742 exim_gnutls_state_st * state = &state_server;
2746 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
2747 if (!tls_refill(*len))
2749 if (!state->xfer_error) return smtp_getbuf(len);
2754 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
2756 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
2757 state->xfer_buffer_lwm += size;
2766 #ifndef DISABLE_DKIM
2767 exim_gnutls_state_st * state = &state_server;
2768 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
2770 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
2776 tls_could_read(void)
2778 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
2779 || gnutls_record_check_pending(state_server.session) > 0;
2785 /*************************************************
2786 * Read bytes from TLS channel *
2787 *************************************************/
2789 /* This does not feed DKIM, so if the caller uses this for reading message body,
2790 then the caller must feed DKIM.
2793 ct_ctx client context pointer, or NULL for the one global server context
2797 Returns: the number of bytes read
2798 -1 after a failed read, including EOF
2802 tls_read(void * ct_ctx, uschar *buff, size_t len)
2804 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
2810 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
2812 debug_printf("*** PROBABLY A BUG *** " \
2813 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
2814 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
2817 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n",
2818 state->session, buff, len);
2821 inbytes = gnutls_record_recv(state->session, buff, len);
2822 while (inbytes == GNUTLS_E_AGAIN);
2824 if (inbytes > 0) return inbytes;
2827 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
2831 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv(\n", __FUNCTION__);
2832 record_io_error(state, (int)inbytes, US"recv", NULL);
2841 /*************************************************
2842 * Write bytes down TLS channel *
2843 *************************************************/
2847 ct_ctx client context pointer, or NULL for the one global server context
2850 more more data expected soon
2852 Returns: the number of bytes after a successful write,
2853 -1 after a failed write
2857 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
2861 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
2863 static BOOL corked = FALSE;
2865 if (more && !corked) gnutls_record_cork(state->session);
2868 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
2869 buff, left, more ? ", more" : "");
2873 DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n",
2877 outbytes = gnutls_record_send(state->session, buff, left);
2878 while (outbytes == GNUTLS_E_AGAIN);
2880 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
2883 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
2884 record_io_error(state, outbytes, US"send", NULL);
2889 record_io_error(state, 0, US"send", US"TLS channel closed on write");
2900 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
2908 if (!more) (void) gnutls_record_uncork(state->session, 0);
2919 /*************************************************
2920 * Random number generation *
2921 *************************************************/
2923 /* Pseudo-random number generation. The result is not expected to be
2924 cryptographically strong but not so weak that someone will shoot themselves
2925 in the foot using it as a nonce in input in some email header scheme or
2926 whatever weirdness they'll twist this into. The result should handle fork()
2927 and avoid repeating sequences. OpenSSL handles that for us.
2931 Returns a random number in range [0, max-1]
2934 #ifdef HAVE_GNUTLS_RND
2936 vaguely_random_number(int max)
2940 uschar smallbuf[sizeof(r)];
2945 needed_len = sizeof(r);
2946 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2947 asked for a number less than 10. */
2949 for (r = max, i = 0; r; ++i)
2955 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
2958 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
2959 return vaguely_random_number_fallback(max);
2962 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
2965 /* We don't particularly care about weighted results; if someone wants
2966 * smooth distribution and cares enough then they should submit a patch then. */
2969 #else /* HAVE_GNUTLS_RND */
2971 vaguely_random_number(int max)
2973 return vaguely_random_number_fallback(max);
2975 #endif /* HAVE_GNUTLS_RND */
2980 /*************************************************
2981 * Let tls_require_ciphers be checked at startup *
2982 *************************************************/
2984 /* The tls_require_ciphers option, if set, must be something which the
2987 Returns: NULL on success, or error message
2991 tls_validate_require_cipher(void)
2994 uschar *expciphers = NULL;
2995 gnutls_priority_t priority_cache;
2997 uschar * dummy_errstr;
2999 #define validate_check_rc(Label) do { \
3000 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3001 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3002 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3004 if (exim_gnutls_base_init_done)
3005 log_write(0, LOG_MAIN|LOG_PANIC,
3006 "already initialised GnuTLS, Exim developer bug");
3008 #ifdef HAVE_GNUTLS_PKCS11
3009 if (!gnutls_allow_auto_pkcs11)
3011 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
3012 validate_check_rc(US"gnutls_pkcs11_init");
3015 rc = gnutls_global_init();
3016 validate_check_rc(US"gnutls_global_init()");
3017 exim_gnutls_base_init_done = TRUE;
3019 if (!(tls_require_ciphers && *tls_require_ciphers))
3020 return_deinit(NULL);
3022 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3024 return_deinit(US"failed to expand tls_require_ciphers");
3026 if (!(expciphers && *expciphers))
3027 return_deinit(NULL);
3030 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3032 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
3033 validate_check_rc(string_sprintf(
3034 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3035 expciphers, errpos - CS expciphers, errpos));
3037 #undef return_deinit
3038 #undef validate_check_rc
3039 gnutls_global_deinit();
3047 /*************************************************
3048 * Report the library versions. *
3049 *************************************************/
3051 /* See a description in tls-openssl.c for an explanation of why this exists.
3053 Arguments: a FILE* to print the results to
3058 tls_version_report(FILE *f)
3060 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
3063 gnutls_check_version(NULL));
3068 /* End of tls-gnu.c */