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 >= 0x030300
74 # define GNUTLS_AUTO_GLOBAL_INIT
76 #if GNUTLS_VERSION_NUMBER >= 0x030500
77 # define SUPPORT_GNUTLS_KEYLOG
79 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
80 # define SUPPORT_SRV_OCSP_STACK
82 #if GNUTLS_VERSION_NUMBER >= 0x030600
83 # define GNUTLS_AUTO_DHPARAMS
85 #if GNUTLS_VERSION_NUMBER >= 0x030603
86 # define EXIM_HAVE_TLS1_3
87 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
88 # define GNUTLS_OCSP_STATUS_REQUEST_GET2
92 # if GNUTLS_VERSION_NUMBER >= 0x030000
93 # define DANESSL_USAGE_DANE_TA 2
94 # define DANESSL_USAGE_DANE_EE 3
96 # error GnuTLS version too early for DANE
98 # if GNUTLS_VERSION_NUMBER < 0x999999
99 # define GNUTLS_BROKEN_DANE_VALIDATION
103 #ifdef EXPERIMENTAL_TLS_RESUME
104 # if GNUTLS_VERSION_NUMBER < 0x030603
105 # error GNUTLS version too early for session-resumption
110 # include <gnutls/ocsp.h>
113 # include <gnutls/dane.h>
116 #include "tls-cipher-stdname.c"
123 # ifdef EXPERIMENTAL_TLS_RESUME
124 builtin_macro_create_var(US
"_RESUME_DECODE", RESUME_DECODE_STRING
);
126 # ifdef EXIM_HAVE_TLS1_3
127 builtin_macro_create(US
"_HAVE_TLS1_3");
136 gnutls_global_set_audit_log_function()
139 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
142 /* Local static variables for GnuTLS */
144 /* Values for verify_requirement */
146 enum peer_verify_requirement
147 { VERIFY_NONE
, VERIFY_OPTIONAL
, VERIFY_REQUIRED
, VERIFY_DANE
};
149 /* This holds most state for server or client; with this, we can set up an
150 outbound TLS-enabled connection in an ACL callout, while not stomping all
151 over the TLS variables available for expansion.
153 Some of these correspond to variables in globals.c; those variables will
154 be set to point to content in one of these instances, as appropriate for
155 the stage of the process lifetime.
157 Not handled here: global tls_channelbinding_b64.
160 typedef struct exim_gnutls_state
{
161 gnutls_session_t session
;
162 gnutls_certificate_credentials_t x509_cred
;
163 gnutls_priority_t priority_cache
;
164 enum peer_verify_requirement verify_requirement
;
167 BOOL peer_cert_verified
;
168 BOOL peer_dane_verified
;
169 BOOL trigger_sni_changes
;
170 BOOL have_set_peerdn
;
171 const struct host_item
*host
; /* NULL if server */
172 gnutls_x509_crt_t peercert
;
175 uschar
*received_sni
;
177 const uschar
*tls_certificate
;
178 const uschar
*tls_privatekey
;
179 const uschar
*tls_sni
; /* client send only, not received */
180 const uschar
*tls_verify_certificates
;
181 const uschar
*tls_crl
;
182 const uschar
*tls_require_ciphers
;
184 uschar
*exp_tls_certificate
;
185 uschar
*exp_tls_privatekey
;
186 uschar
*exp_tls_verify_certificates
;
188 uschar
*exp_tls_require_ciphers
;
189 const uschar
*exp_tls_verify_cert_hostnames
;
190 #ifndef DISABLE_EVENT
191 uschar
*event_action
;
194 char * const * dane_data
;
195 const int * dane_data_len
;
198 tls_support
*tlsp
; /* set in tls_init() */
203 BOOL xfer_eof
; /*XXX never gets set! */
205 } exim_gnutls_state_st
;
207 static const exim_gnutls_state_st exim_gnutls_state_init
= {
208 /* all elements not explicitly intialised here get 0/NULL/FALSE */
213 /* Not only do we have our own APIs which don't pass around state, assuming
214 it's held in globals, GnuTLS doesn't appear to let us register callback data
215 for callbacks, or as part of the session, so we have to keep a "this is the
216 context we're currently dealing with" pointer and rely upon being
217 single-threaded to keep from processing data on an inbound TLS connection while
218 talking to another TLS connection for an outbound check. This does mean that
219 there's no way for heart-beats to be responded to, for the duration of the
221 XXX But see gnutls_session_get_ptr()
224 static exim_gnutls_state_st state_server
;
226 #ifndef GNUTLS_AUTO_DHPARAMS
227 /* dh_params are initialised once within the lifetime of a process using TLS;
228 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
229 don't want to repeat this. */
231 static gnutls_dh_params_t dh_server_params
= NULL
;
234 static int ssl_session_timeout
= 7200; /* Two hours */
236 static const uschar
* const exim_default_gnutls_priority
= US
"NORMAL";
238 /* Guard library core initialisation */
240 static BOOL exim_gnutls_base_init_done
= FALSE
;
243 static BOOL gnutls_buggy_ocsp
= FALSE
;
244 static BOOL exim_testharness_disable_ocsp_validity_check
= FALSE
;
247 #ifdef EXPERIMENTAL_TLS_RESUME
248 static gnutls_datum_t server_sessticket_key
;
251 /* ------------------------------------------------------------------------ */
254 #define MAX_HOST_LEN 255
256 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
257 the library logging; a value less than 0 disables the calls to set up logging
258 callbacks. GNuTLS also looks for an environment variable - except not for
259 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
260 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
261 but the env var must be added to /etc/sudoers too. */
262 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
263 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
266 #ifndef EXIM_CLIENT_DH_MIN_BITS
267 # define EXIM_CLIENT_DH_MIN_BITS 1024
270 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
271 can ask for a bit-strength. Without that, we stick to the constant we had
273 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
274 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
277 #define expand_check_tlsvar(Varname, errstr) \
278 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
280 #if GNUTLS_VERSION_NUMBER >= 0x020c00
281 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
282 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
283 # define HAVE_GNUTLS_RND
284 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
285 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
286 * isn't available sometimes, so this needs to become a conditional
287 * compilation; the sanest way to deal with this being a problem on
288 * older OSes is to block it in the Local/Makefile with this compiler
290 # ifndef AVOID_GNUTLS_PKCS11
291 # define HAVE_GNUTLS_PKCS11
292 # endif /* AVOID_GNUTLS_PKCS11 */
298 /* ------------------------------------------------------------------------ */
299 /* Callback declarations */
301 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
302 static void exim_gnutls_logger_cb(int level
, const char *message
);
305 static int exim_sni_handling_cb(gnutls_session_t session
);
307 #ifdef EXPERIMENTAL_TLS_RESUME
309 tls_server_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
310 unsigned incoming
, const gnutls_datum_t
* msg
);
314 /* Daemon one-time initialisation */
316 tls_daemon_init(void)
318 #ifdef EXPERIMENTAL_TLS_RESUME
319 /* We are dependent on the GnuTLS implementation of the Session Ticket
320 encryption; both the strength and the key rotation period. We hope that
321 the strength at least matches that of the ciphersuite (but GnuTLS does not
324 static BOOL once
= FALSE
;
327 gnutls_session_ticket_key_generate(&server_sessticket_key
); /* >= 2.10.0 */
328 if (f
.running_in_test_harness
) ssl_session_timeout
= 6;
332 /* ------------------------------------------------------------------------ */
333 /* Static functions */
335 /*************************************************
337 *************************************************/
339 /* Called from lots of places when errors occur before actually starting to do
340 the TLS handshake, that is, while the session is still in clear. Always returns
341 DEFER for a server and FAIL for a client so that most calls can use "return
342 tls_error(...)" to do this processing and then give an appropriate return. A
343 single function is used for both server and client, because it is called from
344 some shared functions.
347 prefix text to include in the logged error
348 msg additional error string (may be NULL)
349 usually obtained from gnutls_strerror()
350 host NULL if setting up a server;
351 the connected host if setting up a client
352 errstr pointer to returned error string
354 Returns: OK/DEFER/FAIL
358 tls_error(const uschar
*prefix
, const uschar
*msg
, const host_item
*host
,
362 *errstr
= string_sprintf("(%s)%s%s", prefix
, msg
? ": " : "", msg
? msg
: US
"");
363 return host
? FAIL
: DEFER
;
368 tls_error_gnu(const uschar
*prefix
, int err
, const host_item
*host
,
371 return tls_error(prefix
, US
gnutls_strerror(err
), host
, errstr
);
375 tls_error_sys(const uschar
*prefix
, int err
, const host_item
*host
,
378 return tls_error(prefix
, US
strerror(err
), host
, errstr
);
382 /*************************************************
383 * Deal with logging errors during I/O *
384 *************************************************/
386 /* We have to get the identity of the peer from saved data.
389 state the current GnuTLS exim state container
390 rc the GnuTLS error code, or 0 if it's a local error
391 when text identifying read or write
392 text local error text when rc is 0
398 record_io_error(exim_gnutls_state_st
*state
, int rc
, uschar
*when
, uschar
*text
)
403 if (rc
== GNUTLS_E_FATAL_ALERT_RECEIVED
)
404 msg
= string_sprintf("A TLS fatal alert has been received: %s",
405 US
gnutls_alert_get_name(gnutls_alert_get(state
->session
)));
407 msg
= US
gnutls_strerror(rc
);
409 (void) tls_error(when
, msg
, state
->host
, &errstr
);
412 log_write(0, LOG_MAIN
, "H=%s [%s] TLS error on connection %s",
413 state
->host
->name
, state
->host
->address
, errstr
);
416 uschar
* conn_info
= smtp_get_connection_info();
417 if (Ustrncmp(conn_info
, US
"SMTP ", 5) == 0) conn_info
+= 5;
418 /* I'd like to get separated H= here, but too hard for now */
419 log_write(0, LOG_MAIN
, "TLS error on %s %s", conn_info
, errstr
);
426 /*************************************************
427 * Set various Exim expansion vars *
428 *************************************************/
430 #define exim_gnutls_cert_err(Label) \
433 if (rc != GNUTLS_E_SUCCESS) \
435 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
436 (Label), gnutls_strerror(rc)); \
442 import_cert(const gnutls_datum_t
* cert
, gnutls_x509_crt_t
* crtp
)
446 rc
= gnutls_x509_crt_init(crtp
);
447 exim_gnutls_cert_err(US
"gnutls_x509_crt_init (crt)");
449 rc
= gnutls_x509_crt_import(*crtp
, cert
, GNUTLS_X509_FMT_DER
);
450 exim_gnutls_cert_err(US
"failed to import certificate [gnutls_x509_crt_import(cert)]");
455 #undef exim_gnutls_cert_err
458 /* We set various Exim global variables from the state, once a session has
459 been established. With TLS callouts, may need to change this to stack
460 variables, or just re-call it with the server state after client callout
463 Make sure anything set here is unset in tls_getc().
467 tls_bits strength indicator
468 tls_certificate_verified bool indicator
469 tls_channelbinding_b64 for some SASL mechanisms
471 tls_peercert pointer to library internal
473 tls_sni a (UTF-8) string
474 tls_ourcert pointer to library internal
477 state the relevant exim_gnutls_state_st *
481 extract_exim_vars_from_tls_state(exim_gnutls_state_st
* state
)
483 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
486 gnutls_datum_t channel
;
488 tls_support
* tlsp
= state
->tlsp
;
490 tlsp
->active
.sock
= state
->fd_out
;
491 tlsp
->active
.tls_ctx
= state
;
493 DEBUG(D_tls
) debug_printf("cipher: %s\n", state
->ciphersuite
);
495 tlsp
->certificate_verified
= state
->peer_cert_verified
;
497 tlsp
->dane_verified
= state
->peer_dane_verified
;
500 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
501 only available for use for authenticators while this TLS session is running. */
503 tls_channelbinding_b64
= NULL
;
504 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
507 if ((rc
= gnutls_session_channel_binding(state
->session
, GNUTLS_CB_TLS_UNIQUE
, &channel
)))
508 { DEBUG(D_tls
) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc
)); }
511 old_pool
= store_pool
;
512 store_pool
= POOL_PERM
;
513 tls_channelbinding_b64
= b64encode(CUS channel
.data
, (int)channel
.size
);
514 store_pool
= old_pool
;
515 DEBUG(D_tls
) debug_printf("Have channel bindings cached for possible auth usage.\n");
519 /* peercert is set in peer_status() */
520 tlsp
->peerdn
= state
->peerdn
;
521 tlsp
->sni
= state
->received_sni
;
523 /* record our certificate */
525 const gnutls_datum_t
* cert
= gnutls_certificate_get_ours(state
->session
);
526 gnutls_x509_crt_t crt
;
528 tlsp
->ourcert
= cert
&& import_cert(cert
, &crt
)==0 ? crt
: NULL
;
535 #ifndef GNUTLS_AUTO_DHPARAMS
536 /*************************************************
537 * Setup up DH parameters *
538 *************************************************/
540 /* Generating the D-H parameters may take a long time. They only need to
541 be re-generated every so often, depending on security policy. What we do is to
542 keep these parameters in a file in the spool directory. If the file does not
543 exist, we generate them. This means that it is easy to cause a regeneration.
545 The new file is written as a temporary file and renamed, so that an incomplete
546 file is never present. If two processes both compute some new parameters, you
547 waste a bit of effort, but it doesn't seem worth messing around with locking to
550 Returns: OK/DEFER/FAIL
554 init_server_dh(uschar
** errstr
)
557 unsigned int dh_bits
;
558 gnutls_datum_t m
= {.data
= NULL
, .size
= 0};
559 uschar filename_buf
[PATH_MAX
];
560 uschar
*filename
= NULL
;
562 uschar
*exp_tls_dhparam
;
563 BOOL use_file_in_spool
= FALSE
;
564 host_item
*host
= NULL
; /* dummy for macros */
566 DEBUG(D_tls
) debug_printf("Initialising GnuTLS server params.\n");
568 if ((rc
= gnutls_dh_params_init(&dh_server_params
)))
569 return tls_error_gnu(US
"gnutls_dh_params_init", rc
, host
, errstr
);
571 if (!expand_check(tls_dhparam
, US
"tls_dhparam", &exp_tls_dhparam
, errstr
))
574 if (!exp_tls_dhparam
)
576 DEBUG(D_tls
) debug_printf("Loading default hard-coded DH params\n");
577 m
.data
= US
std_dh_prime_default();
578 m
.size
= Ustrlen(m
.data
);
580 else if (Ustrcmp(exp_tls_dhparam
, "historic") == 0)
581 use_file_in_spool
= TRUE
;
582 else if (Ustrcmp(exp_tls_dhparam
, "none") == 0)
584 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
587 else if (exp_tls_dhparam
[0] != '/')
589 if (!(m
.data
= US
std_dh_prime_named(exp_tls_dhparam
)))
590 return tls_error(US
"No standard prime named", exp_tls_dhparam
, NULL
, errstr
);
591 m
.size
= Ustrlen(m
.data
);
594 filename
= exp_tls_dhparam
;
598 if ((rc
= gnutls_dh_params_import_pkcs3(dh_server_params
, &m
, GNUTLS_X509_FMT_PEM
)))
599 return tls_error_gnu(US
"gnutls_dh_params_import_pkcs3", rc
, host
, errstr
);
600 DEBUG(D_tls
) debug_printf("Loaded fixed standard D-H parameters\n");
604 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
605 /* If you change this constant, also change dh_param_fn_ext so that we can use a
606 different filename and ensure we have sufficient bits. */
608 if (!(dh_bits
= gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH
, GNUTLS_SEC_PARAM_NORMAL
)))
609 return tls_error(US
"gnutls_sec_param_to_pk_bits() failed", NULL
, NULL
, errstr
);
611 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
614 dh_bits
= EXIM_SERVER_DH_BITS_PRE2_12
;
616 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
620 /* Some clients have hard-coded limits. */
621 if (dh_bits
> tls_dh_max_bits
)
624 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
626 dh_bits
= tls_dh_max_bits
;
629 if (use_file_in_spool
)
631 if (!string_format(filename_buf
, sizeof(filename_buf
),
632 "%s/gnutls-params-%d", spool_directory
, dh_bits
))
633 return tls_error(US
"overlong filename", NULL
, NULL
, errstr
);
634 filename
= filename_buf
;
637 /* Open the cache file for reading and if successful, read it and set up the
640 if ((fd
= Uopen(filename
, O_RDONLY
, 0)) >= 0)
646 if (fstat(fd
, &statbuf
) < 0) /* EIO */
650 return tls_error_sys(US
"TLS cache stat failed", saved_errno
, NULL
, errstr
);
652 if (!S_ISREG(statbuf
.st_mode
))
655 return tls_error(US
"TLS cache not a file", NULL
, NULL
, errstr
);
657 if (!(fp
= fdopen(fd
, "rb")))
661 return tls_error_sys(US
"fdopen(TLS cache stat fd) failed",
662 saved_errno
, NULL
, errstr
);
665 m
.size
= statbuf
.st_size
;
666 if (!(m
.data
= store_malloc(m
.size
)))
669 return tls_error_sys(US
"malloc failed", errno
, NULL
, errstr
);
671 if (!(sz
= fread(m
.data
, m
.size
, 1, fp
)))
676 return tls_error_sys(US
"fread failed", saved_errno
, NULL
, errstr
);
680 rc
= gnutls_dh_params_import_pkcs3(dh_server_params
, &m
, GNUTLS_X509_FMT_PEM
);
683 return tls_error_gnu(US
"gnutls_dh_params_import_pkcs3", rc
, host
, errstr
);
684 DEBUG(D_tls
) debug_printf("read D-H parameters from file \"%s\"\n", filename
);
687 /* If the file does not exist, fall through to compute new data and cache it.
688 If there was any other opening error, it is serious. */
690 else if (errno
== ENOENT
)
694 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename
);
697 return tls_error(string_open_failed(errno
, "\"%s\" for reading", filename
),
700 /* If ret < 0, either the cache file does not exist, or the data it contains
701 is not useful. One particular case of this is when upgrading from an older
702 release of Exim in which the data was stored in a different format. We don't
703 try to be clever and support both formats; we just regenerate new data in this
709 unsigned int dh_bits_gen
= dh_bits
;
711 if ((PATH_MAX
- Ustrlen(filename
)) < 10)
712 return tls_error(US
"Filename too long to generate replacement",
713 filename
, NULL
, errstr
);
715 temp_fn
= string_copy(US
"%s.XXXXXXX");
716 if ((fd
= mkstemp(CS temp_fn
)) < 0) /* modifies temp_fn */
717 return tls_error_sys(US
"Unable to open temp file", errno
, NULL
, errstr
);
718 (void)exim_chown(temp_fn
, exim_uid
, exim_gid
); /* Probably not necessary */
720 /* GnuTLS overshoots! If we ask for 2236, we might get 2237 or more. But
721 there's no way to ask GnuTLS how many bits there really are. We can ask
722 how many bits were used in a TLS session, but that's it! The prime itself
723 is hidden behind too much abstraction. So we ask for less, and proceed on
724 a wing and a prayer. First attempt, subtracted 3 for 2233 and got 2240. */
726 if (dh_bits
>= EXIM_CLIENT_DH_MIN_BITS
+ 10)
728 dh_bits_gen
= dh_bits
- 10;
730 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
735 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
737 if ((rc
= gnutls_dh_params_generate2(dh_server_params
, dh_bits_gen
)))
738 return tls_error_gnu(US
"gnutls_dh_params_generate2", rc
, host
, errstr
);
740 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
741 and I confirmed that a NULL call to get the size first is how the GnuTLS
742 sample apps handle this. */
746 if ( (rc
= gnutls_dh_params_export_pkcs3(dh_server_params
,
747 GNUTLS_X509_FMT_PEM
, m
.data
, &sz
))
748 && rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
749 return tls_error_gnu(US
"gnutls_dh_params_export_pkcs3(NULL) sizing",
752 if (!(m
.data
= store_malloc(m
.size
)))
753 return tls_error_sys(US
"memory allocation failed", errno
, NULL
, errstr
);
755 /* this will return a size 1 less than the allocation size above */
756 if ((rc
= gnutls_dh_params_export_pkcs3(dh_server_params
, GNUTLS_X509_FMT_PEM
,
760 return tls_error_gnu(US
"gnutls_dh_params_export_pkcs3() real", rc
, host
, errstr
);
762 m
.size
= sz
; /* shrink by 1, probably */
764 if ((sz
= write_to_fd_buf(fd
, m
.data
, (size_t) m
.size
)) != m
.size
)
767 return tls_error_sys(US
"TLS cache write D-H params failed",
768 errno
, NULL
, errstr
);
771 if ((sz
= write_to_fd_buf(fd
, US
"\n", 1)) != 1)
772 return tls_error_sys(US
"TLS cache write D-H params final newline failed",
773 errno
, NULL
, errstr
);
775 if ((rc
= close(fd
)))
776 return tls_error_sys(US
"TLS cache write close() failed", errno
, NULL
, errstr
);
778 if (Urename(temp_fn
, filename
) < 0)
779 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
780 temp_fn
, filename
), errno
, NULL
, errstr
);
782 DEBUG(D_tls
) debug_printf("wrote D-H parameters to file \"%s\"\n", filename
);
785 DEBUG(D_tls
) debug_printf("initialized server D-H parameters\n");
793 /* Create and install a selfsigned certificate, for use in server mode */
796 tls_install_selfsign(exim_gnutls_state_st
* state
, uschar
** errstr
)
798 gnutls_x509_crt_t cert
= NULL
;
800 gnutls_x509_privkey_t pkey
= NULL
;
801 const uschar
* where
;
804 where
= US
"initialising pkey";
805 if ((rc
= gnutls_x509_privkey_init(&pkey
))) goto err
;
807 where
= US
"initialising cert";
808 if ((rc
= gnutls_x509_crt_init(&cert
))) goto err
;
810 where
= US
"generating pkey";
811 if ((rc
= gnutls_x509_privkey_generate(pkey
, GNUTLS_PK_RSA
,
812 #ifdef SUPPORT_PARAM_TO_PK_BITS
813 # ifndef GNUTLS_SEC_PARAM_MEDIUM
814 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
816 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA
, GNUTLS_SEC_PARAM_MEDIUM
),
823 where
= US
"configuring cert";
825 if ( (rc
= gnutls_x509_crt_set_version(cert
, 3))
826 || (rc
= gnutls_x509_crt_set_serial(cert
, &now
, sizeof(now
)))
827 || (rc
= gnutls_x509_crt_set_activation_time(cert
, now
= time(NULL
)))
828 || (rc
= gnutls_x509_crt_set_expiration_time(cert
, now
+ 60 * 60)) /* 1 hr */
829 || (rc
= gnutls_x509_crt_set_key(cert
, pkey
))
831 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
832 GNUTLS_OID_X520_COUNTRY_NAME
, 0, "UK", 2))
833 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
834 GNUTLS_OID_X520_ORGANIZATION_NAME
, 0, "Exim Developers", 15))
835 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
836 GNUTLS_OID_X520_COMMON_NAME
, 0,
837 smtp_active_hostname
, Ustrlen(smtp_active_hostname
)))
841 where
= US
"signing cert";
842 if ((rc
= gnutls_x509_crt_sign(cert
, cert
, pkey
))) goto err
;
844 where
= US
"installing selfsign cert";
846 if ((rc
= gnutls_certificate_set_x509_key(state
->x509_cred
, &cert
, 1, pkey
)))
852 if (cert
) gnutls_x509_crt_deinit(cert
);
853 if (pkey
) gnutls_x509_privkey_deinit(pkey
);
857 rc
= tls_error_gnu(where
, rc
, NULL
, errstr
);
864 /* Add certificate and key, from files.
867 Zero or negative: good. Negate value for certificate index if < 0.
868 Greater than zero: FAIL or DEFER code.
872 tls_add_certfile(exim_gnutls_state_st
* state
, const host_item
* host
,
873 uschar
* certfile
, uschar
* keyfile
, uschar
** errstr
)
875 int rc
= gnutls_certificate_set_x509_key_file(state
->x509_cred
,
876 CS certfile
, CS keyfile
, GNUTLS_X509_FMT_PEM
);
878 return tls_error_gnu(
879 string_sprintf("cert/key setup: cert=%s key=%s", certfile
, keyfile
),
885 #if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
886 /* Load an OCSP proof from file for sending by the server. Called
887 on getting a status-request handshake message, for earlier versions
891 server_ocsp_stapling_cb(gnutls_session_t session
, void * ptr
,
892 gnutls_datum_t
* ocsp_response
)
895 DEBUG(D_tls
) debug_printf("OCSP stapling callback: %s\n", US ptr
);
897 if ((ret
= gnutls_load_file(ptr
, ocsp_response
)) < 0)
899 DEBUG(D_tls
) debug_printf("Failed to load ocsp stapling file %s\n",
901 tls_in
.ocsp
= OCSP_NOT_RESP
;
902 return GNUTLS_E_NO_CERTIFICATE_STATUS
;
905 tls_in
.ocsp
= OCSP_VFY_NOT_TRIED
;
911 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
912 /* Make a note that we saw a status-request */
914 tls_server_clienthello_ext(void * ctx
, unsigned tls_id
,
915 const unsigned char *data
, unsigned size
)
917 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
918 if (tls_id
== 5) /* status_request */
920 DEBUG(D_tls
) debug_printf("Seen status_request extension from client\n");
921 tls_in
.ocsp
= OCSP_NOT_RESP
;
926 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
928 tls_server_clienthello_cb(gnutls_session_t session
, unsigned int htype
,
929 unsigned when
, unsigned int incoming
, const gnutls_datum_t
* msg
)
931 /* Call fn for each extension seen. 3.6.3 onwards */
932 return gnutls_ext_raw_parse(NULL
, tls_server_clienthello_ext
, msg
,
933 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO
);
937 /* Make a note that we saw a status-response */
939 tls_server_servercerts_ext(void * ctx
, unsigned tls_id
,
940 const unsigned char *data
, unsigned size
)
942 /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
943 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
944 if (FALSE
&& tls_id
== 5) /* status_request */
946 DEBUG(D_tls
) debug_printf("Seen status_request extension\n");
947 tls_in
.ocsp
= exim_testharness_disable_ocsp_validity_check
948 ? OCSP_VFY_NOT_TRIED
: OCSP_VFIED
; /* We know that GnuTLS verifies responses */
953 /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
955 tls_server_servercerts_cb(gnutls_session_t session
, unsigned int htype
,
956 unsigned when
, unsigned int incoming
, const gnutls_datum_t
* msg
)
958 /* Call fn for each extension seen. 3.6.3 onwards */
961 return gnutls_ext_raw_parse(NULL
, tls_server_servercerts_ext
, msg
, 0);
966 /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
967 "Handshake Protocol: Certificate" record.
968 So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
970 This is different to tls1.2 - where it is a separate record (wireshake term) / handshake message (gnutls term).
973 #if defined(EXPERIMENTAL_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
974 /* Callback for certificate-status, on server. We sent stapled OCSP. */
976 tls_server_certstatus_cb(gnutls_session_t session
, unsigned int htype
,
977 unsigned when
, unsigned int incoming
, const gnutls_datum_t
* msg
)
979 DEBUG(D_tls
) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
980 #ifdef SUPPORT_SRV_OCSP_STACK
981 tls_in
.ocsp
= exim_testharness_disable_ocsp_validity_check
982 ? OCSP_VFY_NOT_TRIED
: OCSP_VFIED
; /* We know that GnuTLS verifies responses */
984 tls_in
.ocsp
= OCSP_VFY_NOT_TRIED
;
989 /* Callback for handshake messages, on server */
991 tls_server_hook_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
992 unsigned incoming
, const gnutls_datum_t
* msg
)
994 /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
997 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
998 case GNUTLS_HANDSHAKE_CLIENT_HELLO
:
999 return tls_server_clienthello_cb(sess
, htype
, when
, incoming
, msg
);
1000 case GNUTLS_HANDSHAKE_CERTIFICATE_PKT
:
1001 return tls_server_servercerts_cb(sess
, htype
, when
, incoming
, msg
);
1003 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS
:
1004 return tls_server_certstatus_cb(sess
, htype
, when
, incoming
, msg
);
1005 # ifdef EXPERIMENTAL_TLS_RESUME
1006 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
:
1007 return tls_server_ticket_cb(sess
, htype
, when
, incoming
, msg
);
1016 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1018 tls_server_testharness_ocsp_fiddle(void)
1020 extern char ** environ
;
1021 if (environ
) for (uschar
** p
= USS environ
; *p
; p
++)
1022 if (Ustrncmp(*p
, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1024 DEBUG(D_tls
) debug_printf("Permitting known bad OCSP response\n");
1025 exim_testharness_disable_ocsp_validity_check
= TRUE
;
1030 /*************************************************
1031 * Variables re-expanded post-SNI *
1032 *************************************************/
1034 /* Called from both server and client code, via tls_init(), and also from
1035 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
1037 We can tell the two apart by state->received_sni being non-NULL in callback.
1039 The callback should not call us unless state->trigger_sni_changes is true,
1040 which we are responsible for setting on the first pass through.
1043 state exim_gnutls_state_st *
1044 errstr error string pointer
1046 Returns: OK/DEFER/FAIL
1050 tls_expand_session_files(exim_gnutls_state_st
* state
, uschar
** errstr
)
1052 struct stat statbuf
;
1054 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
1055 uschar
*saved_tls_certificate
= NULL
;
1056 uschar
*saved_tls_privatekey
= NULL
;
1057 uschar
*saved_tls_verify_certificates
= NULL
;
1058 uschar
*saved_tls_crl
= NULL
;
1061 /* We check for tls_sni *before* expansion. */
1062 if (!host
) /* server */
1063 if (!state
->received_sni
)
1065 if ( state
->tls_certificate
1066 && ( Ustrstr(state
->tls_certificate
, US
"tls_sni")
1067 || Ustrstr(state
->tls_certificate
, US
"tls_in_sni")
1068 || Ustrstr(state
->tls_certificate
, US
"tls_out_sni")
1071 DEBUG(D_tls
) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
1072 state
->trigger_sni_changes
= TRUE
;
1077 /* useful for debugging */
1078 saved_tls_certificate
= state
->exp_tls_certificate
;
1079 saved_tls_privatekey
= state
->exp_tls_privatekey
;
1080 saved_tls_verify_certificates
= state
->exp_tls_verify_certificates
;
1081 saved_tls_crl
= state
->exp_tls_crl
;
1084 if ((rc
= gnutls_certificate_allocate_credentials(&state
->x509_cred
)))
1085 return tls_error_gnu(US
"gnutls_certificate_allocate_credentials",
1088 #ifdef SUPPORT_SRV_OCSP_STACK
1089 gnutls_certificate_set_flags(state
->x509_cred
, GNUTLS_CERTIFICATE_API_V2
);
1091 # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1092 if (!host
&& tls_ocsp_file
)
1094 if (f
.running_in_test_harness
)
1095 tls_server_testharness_ocsp_fiddle();
1097 if (exim_testharness_disable_ocsp_validity_check
)
1098 gnutls_certificate_set_flags(state
->x509_cred
,
1099 GNUTLS_CERTIFICATE_API_V2
| GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK
);
1104 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
1105 state members, assuming consistent naming; and expand_check() returns
1106 false if expansion failed, unless expansion was forced to fail. */
1108 /* check if we at least have a certificate, before doing expensive
1111 if (!expand_check_tlsvar(tls_certificate
, errstr
))
1114 /* certificate is mandatory in server, optional in client */
1116 if ( !state
->exp_tls_certificate
1117 || !*state
->exp_tls_certificate
1120 return tls_install_selfsign(state
, errstr
);
1122 DEBUG(D_tls
) debug_printf("TLS: no client certificate specified; okay\n");
1124 if (state
->tls_privatekey
&& !expand_check_tlsvar(tls_privatekey
, errstr
))
1127 /* tls_privatekey is optional, defaulting to same file as certificate */
1129 if (!state
->tls_privatekey
|| !*state
->tls_privatekey
)
1131 state
->tls_privatekey
= state
->tls_certificate
;
1132 state
->exp_tls_privatekey
= state
->exp_tls_certificate
;
1136 if (state
->exp_tls_certificate
&& *state
->exp_tls_certificate
)
1138 DEBUG(D_tls
) debug_printf("certificate file = %s\nkey file = %s\n",
1139 state
->exp_tls_certificate
, state
->exp_tls_privatekey
);
1141 if (state
->received_sni
)
1142 if ( Ustrcmp(state
->exp_tls_certificate
, saved_tls_certificate
) == 0
1143 && Ustrcmp(state
->exp_tls_privatekey
, saved_tls_privatekey
) == 0
1146 DEBUG(D_tls
) debug_printf("TLS SNI: cert and key unchanged\n");
1150 DEBUG(D_tls
) debug_printf("TLS SNI: have a changed cert/key pair.\n");
1153 if (!host
) /* server */
1155 const uschar
* clist
= state
->exp_tls_certificate
;
1156 const uschar
* klist
= state
->exp_tls_privatekey
;
1157 const uschar
* olist
;
1158 int csep
= 0, ksep
= 0, osep
= 0, cnt
= 0;
1159 uschar
* cfile
, * kfile
, * ofile
;
1160 #ifndef DISABLE_OCSP
1161 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1162 gnutls_x509_crt_fmt_t ocsp_fmt
= GNUTLS_X509_FMT_DER
;
1165 if (!expand_check(tls_ocsp_file
, US
"tls_ocsp_file", &ofile
, errstr
))
1170 while (cfile
= string_nextinlist(&clist
, &csep
, NULL
, 0))
1172 if (!(kfile
= string_nextinlist(&klist
, &ksep
, NULL
, 0)))
1173 return tls_error(US
"cert/key setup: out of keys", NULL
, host
, errstr
);
1174 else if (0 < (rc
= tls_add_certfile(state
, host
, cfile
, kfile
, errstr
)))
1178 int gnutls_cert_index
= -rc
;
1179 DEBUG(D_tls
) debug_printf("TLS: cert/key %d %s registered\n",
1180 gnutls_cert_index
, cfile
);
1182 #ifndef DISABLE_OCSP
1185 /* Set the OCSP stapling server info */
1186 if (gnutls_buggy_ocsp
)
1189 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1191 else if ((ofile
= string_nextinlist(&olist
, &osep
, NULL
, 0)))
1193 DEBUG(D_tls
) debug_printf("OCSP response file %d = %s\n",
1194 gnutls_cert_index
, ofile
);
1195 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1196 if (Ustrncmp(ofile
, US
"PEM ", 4) == 0)
1198 ocsp_fmt
= GNUTLS_X509_FMT_PEM
;
1201 else if (Ustrncmp(ofile
, US
"DER ", 4) == 0)
1203 ocsp_fmt
= GNUTLS_X509_FMT_DER
;
1207 if ((rc
= gnutls_certificate_set_ocsp_status_request_file2(
1208 state
->x509_cred
, CCS ofile
, gnutls_cert_index
,
1210 return tls_error_gnu(
1211 US
"gnutls_certificate_set_ocsp_status_request_file2",
1214 debug_printf(" %d response%s loaded\n", rc
, rc
>1 ? "s":"");
1216 /* Arrange callbacks for OCSP request observability */
1218 gnutls_handshake_set_hook_function(state
->session
,
1219 GNUTLS_HANDSHAKE_ANY
, GNUTLS_HOOK_POST
, tls_server_hook_cb
);
1222 # if defined(SUPPORT_SRV_OCSP_STACK)
1223 if ((rc
= gnutls_certificate_set_ocsp_status_request_function2(
1224 state
->x509_cred
, gnutls_cert_index
,
1225 server_ocsp_stapling_cb
, ofile
)))
1226 return tls_error_gnu(
1227 US
"gnutls_certificate_set_ocsp_status_request_function2",
1235 debug_printf("oops; multiple OCSP files not supported\n");
1238 gnutls_certificate_set_ocsp_status_request_function(
1239 state
->x509_cred
, server_ocsp_stapling_cb
, ofile
);
1241 # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
1244 DEBUG(D_tls
) debug_printf("ran out of OCSP response files in list\n");
1246 #endif /* DISABLE_OCSP */
1251 if (0 < (rc
= tls_add_certfile(state
, host
,
1252 state
->exp_tls_certificate
, state
->exp_tls_privatekey
, errstr
)))
1254 DEBUG(D_tls
) debug_printf("TLS: cert/key registered\n");
1257 } /* tls_certificate */
1260 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1261 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1262 error message is provided. However, if we just refrain from setting anything up
1263 in that case, certificate verification fails, which seems to be the correct
1266 if (state
->tls_verify_certificates
&& *state
->tls_verify_certificates
)
1268 if (!expand_check_tlsvar(tls_verify_certificates
, errstr
))
1270 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1271 if (Ustrcmp(state
->exp_tls_verify_certificates
, "system") == 0)
1272 state
->exp_tls_verify_certificates
= NULL
;
1274 if (state
->tls_crl
&& *state
->tls_crl
)
1275 if (!expand_check_tlsvar(tls_crl
, errstr
))
1278 if (!(state
->exp_tls_verify_certificates
&&
1279 *state
->exp_tls_verify_certificates
))
1282 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1283 /* With no tls_verify_certificates, we ignore tls_crl too */
1290 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1294 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1295 if (Ustrcmp(state
->exp_tls_verify_certificates
, "system") == 0)
1296 cert_count
= gnutls_certificate_set_x509_system_trust(state
->x509_cred
);
1300 if (Ustat(state
->exp_tls_verify_certificates
, &statbuf
) < 0)
1302 log_write(0, LOG_MAIN
|LOG_PANIC
, "could not stat '%s' "
1303 "(tls_verify_certificates): %s", state
->exp_tls_verify_certificates
,
1308 #ifndef SUPPORT_CA_DIR
1309 /* The test suite passes in /dev/null; we could check for that path explicitly,
1310 but who knows if someone has some weird FIFO which always dumps some certs, or
1311 other weirdness. The thing we really want to check is that it's not a
1312 directory, since while OpenSSL supports that, GnuTLS does not.
1313 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1314 if (S_ISDIR(statbuf
.st_mode
))
1317 debug_printf("verify certificates path is a dir: \"%s\"\n",
1318 state
->exp_tls_verify_certificates
);
1319 log_write(0, LOG_MAIN
|LOG_PANIC
,
1320 "tls_verify_certificates \"%s\" is a directory",
1321 state
->exp_tls_verify_certificates
);
1326 DEBUG(D_tls
) debug_printf("verify certificates = %s size=" OFF_T_FMT
"\n",
1327 state
->exp_tls_verify_certificates
, statbuf
.st_size
);
1329 if (statbuf
.st_size
== 0)
1332 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1338 #ifdef SUPPORT_CA_DIR
1339 (statbuf
.st_mode
& S_IFMT
) == S_IFDIR
1341 gnutls_certificate_set_x509_trust_dir(state
->x509_cred
,
1342 CS state
->exp_tls_verify_certificates
, GNUTLS_X509_FMT_PEM
)
1345 gnutls_certificate_set_x509_trust_file(state
->x509_cred
,
1346 CS state
->exp_tls_verify_certificates
, GNUTLS_X509_FMT_PEM
);
1348 #ifdef SUPPORT_CA_DIR
1349 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1350 when using the directory-of-certs config model. */
1352 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
1353 gnutls_certificate_send_x509_rdn_sequence(state
->session
, 1);
1358 return tls_error_gnu(US
"setting certificate trust", cert_count
, host
, errstr
);
1360 debug_printf("Added %d certificate authorities.\n", cert_count
);
1362 if (state
->tls_crl
&& *state
->tls_crl
&&
1363 state
->exp_tls_crl
&& *state
->exp_tls_crl
)
1365 DEBUG(D_tls
) debug_printf("loading CRL file = %s\n", state
->exp_tls_crl
);
1366 if ((cert_count
= gnutls_certificate_set_x509_crl_file(state
->x509_cred
,
1367 CS state
->exp_tls_crl
, GNUTLS_X509_FMT_PEM
)) < 0)
1368 return tls_error_gnu(US
"gnutls_certificate_set_x509_crl_file",
1369 cert_count
, host
, errstr
);
1371 DEBUG(D_tls
) debug_printf("Processed %d CRLs.\n", cert_count
);
1380 /*************************************************
1381 * Set X.509 state variables *
1382 *************************************************/
1384 /* In GnuTLS, the registered cert/key are not replaced by a later
1385 set of a cert/key, so for SNI support we need a whole new x509_cred
1386 structure. Which means various other non-re-expanded pieces of state
1387 need to be re-set in the new struct, so the setting logic is pulled
1391 state exim_gnutls_state_st *
1392 errstr error string pointer
1394 Returns: OK/DEFER/FAIL
1398 tls_set_remaining_x509(exim_gnutls_state_st
*state
, uschar
** errstr
)
1401 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
1403 #ifndef GNUTLS_AUTO_DHPARAMS
1404 /* Create D-H parameters, or read them from the cache file. This function does
1405 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1406 client-side params. */
1410 if (!dh_server_params
)
1411 if ((rc
= init_server_dh(errstr
)) != OK
) return rc
;
1413 /* Unnecessary & discouraged with 3.6.0 or later */
1414 gnutls_certificate_set_dh_params(state
->x509_cred
, dh_server_params
);
1418 /* Link the credentials to the session. */
1420 if ((rc
= gnutls_credentials_set(state
->session
,
1421 GNUTLS_CRD_CERTIFICATE
, state
->x509_cred
)))
1422 return tls_error_gnu(US
"gnutls_credentials_set", rc
, host
, errstr
);
1427 /*************************************************
1428 * Initialize for GnuTLS *
1429 *************************************************/
1432 #ifndef DISABLE_OCSP
1435 tls_is_buggy_ocsp(void)
1438 uschar maj
, mid
, mic
;
1440 s
= CUS
gnutls_check_version(NULL
);
1444 while (*s
&& *s
!= '.') s
++;
1445 mid
= atoi(CCS
++s
);
1452 while (*s
&& *s
!= '.') s
++;
1453 mic
= atoi(CCS
++s
);
1454 return mic
<= (mid
== 3 ? 16 : 3);
1463 /* Called from both server and client code. In the case of a server, errors
1464 before actual TLS negotiation return DEFER.
1467 host connected host, if client; NULL if server
1468 certificate certificate file
1469 privatekey private key file
1470 sni TLS SNI to send, sometimes when client; else NULL
1473 require_ciphers tls_require_ciphers setting
1474 caller_state returned state-info structure
1475 errstr error string pointer
1477 Returns: OK/DEFER/FAIL
1482 const host_item
*host
,
1483 const uschar
*certificate
,
1484 const uschar
*privatekey
,
1488 const uschar
*require_ciphers
,
1489 exim_gnutls_state_st
**caller_state
,
1493 exim_gnutls_state_st
* state
;
1496 const char * errpos
;
1499 if (!exim_gnutls_base_init_done
)
1501 DEBUG(D_tls
) debug_printf("GnuTLS global init required.\n");
1503 #ifdef HAVE_GNUTLS_PKCS11
1504 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1505 which loads modules from a config file, which sounds good and may be wanted
1506 by some sysadmin, but also means in common configurations that GNOME keyring
1507 environment variables are used and so breaks for users calling mailq.
1508 To prevent this, we init PKCS11 first, which is the documented approach. */
1509 if (!gnutls_allow_auto_pkcs11
)
1510 if ((rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
)))
1511 return tls_error_gnu(US
"gnutls_pkcs11_init", rc
, host
, errstr
);
1514 #ifndef GNUTLS_AUTO_GLOBAL_INIT
1515 if ((rc
= gnutls_global_init()))
1516 return tls_error_gnu(US
"gnutls_global_init", rc
, host
, errstr
);
1519 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1522 gnutls_global_set_log_function(exim_gnutls_logger_cb
);
1523 /* arbitrarily chosen level; bump up to 9 for more */
1524 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL
);
1528 #ifndef DISABLE_OCSP
1529 if (tls_ocsp_file
&& (gnutls_buggy_ocsp
= tls_is_buggy_ocsp()))
1530 log_write(0, LOG_MAIN
, "OCSP unusable with this GnuTLS library version");
1533 exim_gnutls_base_init_done
= TRUE
;
1538 /* For client-side sessions we allocate a context. This lets us run
1539 several in parallel. */
1540 int old_pool
= store_pool
;
1541 store_pool
= POOL_PERM
;
1542 state
= store_get(sizeof(exim_gnutls_state_st
), FALSE
);
1543 store_pool
= old_pool
;
1545 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1547 DEBUG(D_tls
) debug_printf("initialising GnuTLS client session\n");
1548 rc
= gnutls_init(&state
->session
, GNUTLS_CLIENT
);
1552 state
= &state_server
;
1553 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1555 DEBUG(D_tls
) debug_printf("initialising GnuTLS server session\n");
1556 rc
= gnutls_init(&state
->session
, GNUTLS_SERVER
);
1559 return tls_error_gnu(US
"gnutls_init", rc
, host
, errstr
);
1563 state
->tls_certificate
= certificate
;
1564 state
->tls_privatekey
= privatekey
;
1565 state
->tls_require_ciphers
= require_ciphers
;
1566 state
->tls_sni
= sni
;
1567 state
->tls_verify_certificates
= cas
;
1568 state
->tls_crl
= crl
;
1570 /* This handles the variables that might get re-expanded after TLS SNI;
1571 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1574 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1575 if ((rc
= tls_expand_session_files(state
, errstr
)) != OK
) return rc
;
1577 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1578 requires a new structure afterwards. */
1580 if ((rc
= tls_set_remaining_x509(state
, errstr
)) != OK
) return rc
;
1582 /* set SNI in client, only */
1585 if (!expand_check(sni
, US
"tls_out_sni", &state
->tlsp
->sni
, errstr
))
1587 if (state
->tlsp
->sni
&& *state
->tlsp
->sni
)
1590 debug_printf("Setting TLS client SNI to \"%s\"\n", state
->tlsp
->sni
);
1591 sz
= Ustrlen(state
->tlsp
->sni
);
1592 if ((rc
= gnutls_server_name_set(state
->session
,
1593 GNUTLS_NAME_DNS
, state
->tlsp
->sni
, sz
)))
1594 return tls_error_gnu(US
"gnutls_server_name_set", rc
, host
, errstr
);
1597 else if (state
->tls_sni
)
1598 DEBUG(D_tls
) debug_printf("*** PROBABLY A BUG *** " \
1599 "have an SNI set for a server [%s]\n", state
->tls_sni
);
1601 /* This is the priority string support,
1602 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1603 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1604 This was backwards incompatible, but means Exim no longer needs to track
1605 all algorithms and provide string forms for them. */
1608 if (state
->tls_require_ciphers
&& *state
->tls_require_ciphers
)
1610 if (!expand_check_tlsvar(tls_require_ciphers
, errstr
))
1612 if (state
->exp_tls_require_ciphers
&& *state
->exp_tls_require_ciphers
)
1614 p
= state
->exp_tls_require_ciphers
;
1615 DEBUG(D_tls
) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p
);
1620 p
= exim_default_gnutls_priority
;
1622 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p
);
1625 if ((rc
= gnutls_priority_init(&state
->priority_cache
, CCS p
, &errpos
)))
1626 return tls_error_gnu(string_sprintf(
1627 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1628 p
, errpos
- CS p
, errpos
),
1631 if ((rc
= gnutls_priority_set(state
->session
, state
->priority_cache
)))
1632 return tls_error_gnu(US
"gnutls_priority_set", rc
, host
, errstr
);
1634 /* This also sets the server ticket expiration time to the same, and
1635 the STEK rotation time to 3x. */
1637 gnutls_db_set_cache_expiration(state
->session
, ssl_session_timeout
);
1639 /* Reduce security in favour of increased compatibility, if the admin
1640 decides to make that trade-off. */
1641 if (gnutls_compat_mode
)
1643 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1644 DEBUG(D_tls
) debug_printf("lowering GnuTLS security, compatibility mode\n");
1645 gnutls_session_enable_compatibility_mode(state
->session
);
1647 DEBUG(D_tls
) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1651 *caller_state
= state
;
1657 /*************************************************
1658 * Extract peer information *
1659 *************************************************/
1661 static const uschar
*
1662 cipher_stdname_kcm(gnutls_kx_algorithm_t kx
, gnutls_cipher_algorithm_t cipher
,
1663 gnutls_mac_algorithm_t mac
)
1666 gnutls_kx_algorithm_t kx_i
;
1667 gnutls_cipher_algorithm_t cipher_i
;
1668 gnutls_mac_algorithm_t mac_i
;
1671 gnutls_cipher_suite_info(i
, cs_id
, &kx_i
, &cipher_i
, &mac_i
, NULL
);
1673 if (kx_i
== kx
&& cipher_i
== cipher
&& mac_i
== mac
)
1674 return cipher_stdname(cs_id
[0], cs_id
[1]);
1680 /* Called from both server and client code.
1681 Only this is allowed to set state->peerdn and state->have_set_peerdn
1682 and we use that to detect double-calls.
1684 NOTE: the state blocks last while the TLS connection is up, which is fine
1685 for logging in the server side, but for the client side, we log after teardown
1686 in src/deliver.c. While the session is up, we can twist about states and
1687 repoint tls_* globals, but those variables used for logging or other variable
1688 expansion that happens _after_ delivery need to have a longer life-time.
1690 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1691 doing this more than once per generation of a state context. We set them in
1692 the state context, and repoint tls_* to them. After the state goes away, the
1693 tls_* copies of the pointers remain valid and client delivery logging is happy.
1695 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1699 state exim_gnutls_state_st *
1700 errstr pointer to error string
1702 Returns: OK/DEFER/FAIL
1706 peer_status(exim_gnutls_state_st
* state
, uschar
** errstr
)
1708 gnutls_session_t session
= state
->session
;
1709 const gnutls_datum_t
* cert_list
;
1711 unsigned int cert_list_size
= 0;
1712 gnutls_protocol_t protocol
;
1713 gnutls_cipher_algorithm_t cipher
;
1714 gnutls_kx_algorithm_t kx
;
1715 gnutls_mac_algorithm_t mac
;
1716 gnutls_certificate_type_t ct
;
1717 gnutls_x509_crt_t crt
;
1721 if (state
->have_set_peerdn
)
1723 state
->have_set_peerdn
= TRUE
;
1725 state
->peerdn
= NULL
;
1728 cipher
= gnutls_cipher_get(session
);
1729 protocol
= gnutls_protocol_get_version(session
);
1730 mac
= gnutls_mac_get(session
);
1732 #ifdef GNUTLS_TLS1_3
1733 protocol
>= GNUTLS_TLS1_3
? 0 :
1735 gnutls_kx_get(session
);
1737 old_pool
= store_pool
;
1739 tls_support
* tlsp
= state
->tlsp
;
1740 store_pool
= POOL_PERM
;
1742 #ifdef SUPPORT_GNUTLS_SESS_DESC
1745 uschar
* s
= US
gnutls_session_get_desc(session
), c
;
1747 /* Nikos M suggests we use this by preference. It returns like:
1748 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
1750 For partial back-compat, put a colon after the TLS version, replace the
1751 )-( grouping with __, replace in-group - with _ and append the :keysize. */
1753 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
1755 for (s
++; (c
= *s
) && c
!= ')'; s
++) g
= string_catn(g
, s
, 1);
1756 g
= string_catn(g
, US
":", 1);
1757 if (*s
) s
++; /* now on _ between groups */
1760 for (*++s
&& ++s
; (c
= *s
) && c
!= ')'; s
++) g
= string_catn(g
, c
== '-' ? US
"_" : s
, 1);
1761 /* now on ) closing group */
1762 if ((c
= *s
) && *++s
== '-') g
= string_catn(g
, US
"__", 2);
1763 /* now on _ between groups */
1765 g
= string_catn(g
, US
":", 1);
1766 g
= string_cat(g
, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher
) * 8));
1767 state
->ciphersuite
= string_from_gstring(g
);
1770 state
->ciphersuite
= string_sprintf("%s:%s:%d",
1771 gnutls_protocol_get_name(protocol
),
1772 gnutls_cipher_suite_get_name(kx
, cipher
, mac
),
1773 (int) gnutls_cipher_get_key_size(cipher
) * 8);
1775 /* I don't see a way that spaces could occur, in the current GnuTLS
1776 code base, but it was a concern in the old code and perhaps older GnuTLS
1777 releases did return "TLS 1.0"; play it safe, just in case. */
1779 for (uschar
* p
= state
->ciphersuite
; *p
; p
++) if (isspace(*p
)) *p
= '-';
1782 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
1784 tlsp
->cipher
= state
->ciphersuite
;
1785 tlsp
->bits
= gnutls_cipher_get_key_size(cipher
) * 8;
1787 tlsp
->cipher_stdname
= cipher_stdname_kcm(kx
, cipher
, mac
);
1789 store_pool
= old_pool
;
1792 cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
);
1794 if (!cert_list
|| cert_list_size
== 0)
1796 DEBUG(D_tls
) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1797 cert_list
, cert_list_size
);
1798 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1799 return tls_error(US
"certificate verification failed",
1800 US
"no certificate received from peer", state
->host
, errstr
);
1804 if ((ct
= gnutls_certificate_type_get(session
)) != GNUTLS_CRT_X509
)
1806 const uschar
* ctn
= US
gnutls_certificate_type_get_name(ct
);
1808 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn
);
1809 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1810 return tls_error(US
"certificate verification not possible, unhandled type",
1811 ctn
, state
->host
, errstr
);
1815 #define exim_gnutls_peer_err(Label) \
1817 if (rc != GNUTLS_E_SUCCESS) \
1819 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1820 (Label), gnutls_strerror(rc)); \
1821 if (state->verify_requirement >= VERIFY_REQUIRED) \
1822 return tls_error_gnu((Label), rc, state->host, errstr); \
1827 rc
= import_cert(&cert_list
[0], &crt
);
1828 exim_gnutls_peer_err(US
"cert 0");
1830 state
->tlsp
->peercert
= state
->peercert
= crt
;
1833 rc
= gnutls_x509_crt_get_dn(crt
, NULL
, &sz
);
1834 if (rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
1836 exim_gnutls_peer_err(US
"getting size for cert DN failed");
1837 return FAIL
; /* should not happen */
1839 dn_buf
= store_get_perm(sz
, TRUE
); /* tainted */
1840 rc
= gnutls_x509_crt_get_dn(crt
, CS dn_buf
, &sz
);
1841 exim_gnutls_peer_err(US
"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1843 state
->peerdn
= dn_buf
;
1846 #undef exim_gnutls_peer_err
1852 /*************************************************
1853 * Verify peer certificate *
1854 *************************************************/
1856 /* Called from both server and client code.
1857 *Should* be using a callback registered with
1858 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1859 the peer information, but that's too new for some OSes.
1862 state exim_gnutls_state_st *
1863 errstr where to put an error message
1866 FALSE if the session should be rejected
1867 TRUE if the cert is okay or we just don't care
1871 verify_certificate(exim_gnutls_state_st
* state
, uschar
** errstr
)
1876 DEBUG(D_tls
) debug_printf("TLS: checking peer certificate\n");
1878 rc
= peer_status(state
, errstr
);
1880 if (state
->verify_requirement
== VERIFY_NONE
)
1883 if (rc
!= OK
|| !state
->peerdn
)
1885 verify
= GNUTLS_CERT_INVALID
;
1886 *errstr
= US
"certificate not supplied";
1892 if (state
->verify_requirement
== VERIFY_DANE
&& state
->host
)
1894 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1895 including talking to a DNS resolver. But we want to do that bit ourselves
1896 as the testsuite intercepts and fakes its own DNS environment. */
1901 const gnutls_datum_t
* certlist
=
1902 gnutls_certificate_get_peers(state
->session
, &lsize
);
1903 int usage
= tls_out
.tlsa_usage
;
1905 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1906 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1907 dane-verification separately so that we know which selector verified;
1908 then we know whether to do name-verification (needed for TA but not EE). */
1910 if (usage
== ((1<<DANESSL_USAGE_DANE_TA
) | (1<<DANESSL_USAGE_DANE_EE
)))
1911 { /* a mixed-usage bundle */
1916 for(nrec
= 0; state
->dane_data_len
[nrec
]; ) nrec
++;
1919 dd
= store_get(nrec
* sizeof(uschar
*), FALSE
);
1920 ddl
= store_get(nrec
* sizeof(int), FALSE
);
1923 if ((rc
= dane_state_init(&s
, 0)))
1926 for (usage
= DANESSL_USAGE_DANE_EE
;
1927 usage
>= DANESSL_USAGE_DANE_TA
; usage
--)
1928 { /* take records with this usage */
1929 for (j
= i
= 0; i
< nrec
; i
++)
1930 if (state
->dane_data
[i
][0] == usage
)
1932 dd
[j
] = state
->dane_data
[i
];
1933 ddl
[j
++] = state
->dane_data_len
[i
];
1940 if ((rc
= dane_raw_tlsa(s
, &r
, (char * const *)dd
, ddl
, 1, 0)))
1943 if ((rc
= dane_verify_crt_raw(s
, certlist
, lsize
,
1944 gnutls_certificate_type_get(state
->session
),
1946 usage
== DANESSL_USAGE_DANE_EE
1947 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE
: 0,
1951 debug_printf("TLSA record problem: %s\n", dane_strerror(rc
));
1953 else if (verify
== 0) /* verification passed */
1961 if (rc
) goto tlsa_prob
;
1966 if ( (rc
= dane_state_init(&s
, 0))
1967 || (rc
= dane_raw_tlsa(s
, &r
, state
->dane_data
, state
->dane_data_len
,
1969 || (rc
= dane_verify_crt_raw(s
, certlist
, lsize
,
1970 gnutls_certificate_type_get(state
->session
),
1972 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1973 usage
== (1 << DANESSL_USAGE_DANE_EE
)
1974 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE
: 0,
1983 if (verify
!= 0) /* verification failed */
1986 (void) dane_verification_status_print(verify
, &str
, 0);
1987 *errstr
= US str
.data
; /* don't bother to free */
1991 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1992 /* If a TA-mode TLSA record was used for verification we must additionally
1993 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1995 if (usage
& (1 << DANESSL_USAGE_DANE_EE
))
1998 state
->peer_dane_verified
= state
->peer_cert_verified
= TRUE
;
2001 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
2002 /* Assume that the name on the A-record is the one that should be matching
2003 the cert. An alternate view is that the domain part of the email address
2004 is also permissible. */
2006 if (gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
,
2007 CS state
->host
->name
))
2009 state
->peer_dane_verified
= state
->peer_cert_verified
= TRUE
;
2014 #endif /*SUPPORT_DANE*/
2016 rc
= gnutls_certificate_verify_peers2(state
->session
, &verify
);
2019 /* Handle the result of verification. INVALID is set if any others are. */
2021 if (rc
< 0 || verify
& (GNUTLS_CERT_INVALID
|GNUTLS_CERT_REVOKED
))
2023 state
->peer_cert_verified
= FALSE
;
2026 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
2031 if (gnutls_certificate_verification_status_print(verify
,
2032 gnutls_certificate_type_get(state
->session
), &txt
, 0)
2033 == GNUTLS_E_SUCCESS
)
2035 debug_printf("%s\n", txt
.data
);
2036 gnutls_free(txt
.data
);
2040 *errstr
= verify
& GNUTLS_CERT_REVOKED
2041 ? US
"certificate revoked" : US
"certificate invalid";
2045 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
2046 *errstr
, state
->peerdn
? state
->peerdn
: US
"<unset>");
2048 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
2051 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
2056 /* Client side, check the server's certificate name versus the name on the
2057 A-record for the connection we made. What to do for server side - what name
2058 to use for client? We document that there is no such checking for server
2061 if ( state
->exp_tls_verify_cert_hostnames
2062 && !gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
,
2063 CS state
->exp_tls_verify_cert_hostnames
)
2067 debug_printf("TLS certificate verification failed: cert name mismatch\n");
2068 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
2073 state
->peer_cert_verified
= TRUE
;
2074 DEBUG(D_tls
) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
2075 state
->peerdn
? state
->peerdn
: US
"<unset>");
2079 state
->tlsp
->peerdn
= state
->peerdn
;
2084 *errstr
= string_sprintf("TLSA record problem: %s",
2085 rc
== DANE_E_REQUESTED_DATA_NOT_AVAILABLE
? "none usable" : dane_strerror(rc
));
2089 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_BAD_CERTIFICATE
);
2096 /* ------------------------------------------------------------------------ */
2099 /* Logging function which can be registered with
2100 * gnutls_global_set_log_function()
2101 * gnutls_global_set_log_level() 0..9
2103 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2105 exim_gnutls_logger_cb(int level
, const char *message
)
2107 size_t len
= strlen(message
);
2110 DEBUG(D_tls
) debug_printf("GnuTLS<%d> empty debug message\n", level
);
2113 DEBUG(D_tls
) debug_printf("GnuTLS<%d>: %s%s", level
, message
,
2114 message
[len
-1] == '\n' ? "" : "\n");
2119 /* Called after client hello, should handle SNI work.
2120 This will always set tls_sni (state->received_sni) if available,
2121 and may trigger presenting different certificates,
2122 if state->trigger_sni_changes is TRUE.
2124 Should be registered with
2125 gnutls_handshake_set_post_client_hello_function()
2127 "This callback must return 0 on success or a gnutls error code to terminate the
2130 For inability to get SNI information, we return 0.
2131 We only return non-zero if re-setup failed.
2132 Only used for server-side TLS.
2136 exim_sni_handling_cb(gnutls_session_t session
)
2138 char sni_name
[MAX_HOST_LEN
];
2139 size_t data_len
= MAX_HOST_LEN
;
2140 exim_gnutls_state_st
*state
= &state_server
;
2141 unsigned int sni_type
;
2143 uschar
* dummy_errstr
;
2145 rc
= gnutls_server_name_get(session
, sni_name
, &data_len
, &sni_type
, 0);
2146 if (rc
!= GNUTLS_E_SUCCESS
)
2149 if (rc
== GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
)
2150 debug_printf("TLS: no SNI presented in handshake.\n");
2152 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2153 gnutls_strerror(rc
), rc
);
2157 if (sni_type
!= GNUTLS_NAME_DNS
)
2159 DEBUG(D_tls
) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type
);
2163 /* We now have a UTF-8 string in sni_name */
2164 old_pool
= store_pool
;
2165 store_pool
= POOL_PERM
;
2166 state
->received_sni
= string_copy_taint(US sni_name
, TRUE
);
2167 store_pool
= old_pool
;
2169 /* We set this one now so that variable expansions below will work */
2170 state
->tlsp
->sni
= state
->received_sni
;
2172 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name
,
2173 state
->trigger_sni_changes
? "" : " (unused for certificate selection)");
2175 if (!state
->trigger_sni_changes
)
2178 if ((rc
= tls_expand_session_files(state
, &dummy_errstr
)) != OK
)
2180 /* If the setup of certs/etc failed before handshake, TLS would not have
2181 been offered. The best we can do now is abort. */
2182 return GNUTLS_E_APPLICATION_ERROR_MIN
;
2185 rc
= tls_set_remaining_x509(state
, &dummy_errstr
);
2186 if (rc
!= OK
) return GNUTLS_E_APPLICATION_ERROR_MIN
;
2193 #ifndef DISABLE_EVENT
2195 We use this callback to get observability and detail-level control
2196 for an exim TLS connection (either direction), raising a tls:cert event
2197 for each cert in the chain presented by the peer. Any event
2198 can deny verification.
2200 Return 0 for the handshake to continue or non-zero to terminate.
2204 verify_cb(gnutls_session_t session
)
2206 const gnutls_datum_t
* cert_list
;
2207 unsigned int cert_list_size
= 0;
2208 gnutls_x509_crt_t crt
;
2211 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(session
);
2213 if ((cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
)))
2214 while (cert_list_size
--)
2216 if ((rc
= import_cert(&cert_list
[cert_list_size
], &crt
)) != GNUTLS_E_SUCCESS
)
2218 DEBUG(D_tls
) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2219 cert_list_size
, gnutls_strerror(rc
));
2223 state
->tlsp
->peercert
= crt
;
2224 if ((yield
= event_raise(state
->event_action
,
2225 US
"tls:cert", string_sprintf("%d", cert_list_size
))))
2227 log_write(0, LOG_MAIN
,
2228 "SSL verify denied by event-action: depth=%d: %s",
2229 cert_list_size
, yield
);
2230 return 1; /* reject */
2232 state
->tlsp
->peercert
= NULL
;
2242 ddump(gnutls_datum_t
* d
)
2244 gstring
* g
= string_get((d
->size
+1) * 2);
2245 uschar
* s
= d
->data
;
2246 for (unsigned i
= d
->size
; i
> 0; i
--, s
++)
2248 g
= string_catn(g
, US
"0123456789abcdef" + (*s
>> 4), 1);
2249 g
= string_catn(g
, US
"0123456789abcdef" + (*s
& 0xf), 1);
2255 post_handshake_debug(exim_gnutls_state_st
* state
)
2257 #ifdef SUPPORT_GNUTLS_SESS_DESC
2258 debug_printf("%s\n", gnutls_session_get_desc(state
->session
));
2260 #ifdef SUPPORT_GNUTLS_KEYLOG
2262 # ifdef EXIM_HAVE_TLS1_3
2263 if (gnutls_protocol_get_version(state
->session
) < GNUTLS_TLS1_3
)
2268 gnutls_datum_t c
, s
;
2270 /* we only want the client random and the master secret */
2271 gnutls_session_get_random(state
->session
, &c
, &s
);
2272 gnutls_session_get_master_secret(state
->session
, &s
);
2275 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc
->ptr
, gc
->s
, (int)gs
->ptr
, gs
->s
);
2278 debug_printf("To get keying info for TLS1.3 is hard:\n"
2279 " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
2280 " add SSLKEYLOGFILE to keep_environment in the exim config\n"
2281 " run exim as root\n"
2282 " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
2283 " (works for TLS1.2 also, and saves cut-paste into file)\n");
2288 #ifdef EXPERIMENTAL_TLS_RESUME
2290 tls_server_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
2291 unsigned incoming
, const gnutls_datum_t
* msg
)
2293 DEBUG(D_tls
) debug_printf("newticket cb\n");
2294 tls_in
.resumption
|= RESUME_CLIENT_REQUESTED
;
2299 tls_server_resume_prehandshake(exim_gnutls_state_st
* state
)
2301 /* Should the server offer session resumption? */
2302 tls_in
.resumption
= RESUME_SUPPORTED
;
2303 if (verify_check_host(&tls_resumption_hosts
) == OK
)
2306 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2307 an offered resumption is unacceptable. We lose one resumption per ticket
2308 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2309 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2310 least they go out in a single packet. */
2312 if (!(rc
= gnutls_session_ticket_enable_server(state
->session
,
2313 &server_sessticket_key
)))
2314 tls_in
.resumption
|= RESUME_SERVER_TICKET
;
2317 debug_printf("enabling session tickets: %s\n", US
gnutls_strerror(rc
));
2319 /* Try to tell if we see a ticket request */
2320 gnutls_handshake_set_hook_function(state
->session
,
2321 GNUTLS_HANDSHAKE_ANY
, GNUTLS_HOOK_POST
, tls_server_hook_cb
);
2326 tls_server_resume_posthandshake(exim_gnutls_state_st
* state
)
2328 if (gnutls_session_resumption_requested(state
->session
))
2330 /* This tells us the client sent a full ticket. We use a
2331 callback on session-ticket request, elsewhere, to tell
2332 if a client asked for a ticket. */
2334 tls_in
.resumption
|= RESUME_CLIENT_SUGGESTED
;
2335 DEBUG(D_tls
) debug_printf("client requested resumption\n");
2337 if (gnutls_session_is_resumed(state
->session
))
2339 tls_in
.resumption
|= RESUME_USED
;
2340 DEBUG(D_tls
) debug_printf("Session resumed\n");
2344 /* ------------------------------------------------------------------------ */
2345 /* Exported functions */
2350 /*************************************************
2351 * Start a TLS session in a server *
2352 *************************************************/
2354 /* This is called when Exim is running as a server, after having received
2355 the STARTTLS command. It must respond to that command, and then negotiate
2359 require_ciphers list of allowed ciphers or NULL
2360 errstr pointer to error string
2362 Returns: OK on success
2363 DEFER for errors before the start of the negotiation
2364 FAIL for errors during the negotiation; the server can't
2369 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
2372 exim_gnutls_state_st
* state
= NULL
;
2374 /* Check for previous activation */
2375 if (tls_in
.active
.sock
>= 0)
2377 tls_error(US
"STARTTLS received after TLS started", US
"", NULL
, errstr
);
2378 smtp_printf("554 Already in TLS\r\n", FALSE
);
2382 /* Initialize the library. If it fails, it will already have logged the error
2383 and sent an SMTP response. */
2385 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a server\n");
2387 if ((rc
= tls_init(NULL
, tls_certificate
, tls_privatekey
,
2388 NULL
, tls_verify_certificates
, tls_crl
,
2389 require_ciphers
, &state
, &tls_in
, errstr
)) != OK
) return rc
;
2391 #ifdef EXPERIMENTAL_TLS_RESUME
2392 tls_server_resume_prehandshake(state
);
2395 /* If this is a host for which certificate verification is mandatory or
2396 optional, set up appropriately. */
2398 if (verify_check_host(&tls_verify_hosts
) == OK
)
2401 debug_printf("TLS: a client certificate will be required.\n");
2402 state
->verify_requirement
= VERIFY_REQUIRED
;
2403 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2405 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
2408 debug_printf("TLS: a client certificate will be requested but not required.\n");
2409 state
->verify_requirement
= VERIFY_OPTIONAL
;
2410 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2415 debug_printf("TLS: a client certificate will not be requested.\n");
2416 state
->verify_requirement
= VERIFY_NONE
;
2417 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2420 #ifndef DISABLE_EVENT
2423 state
->event_action
= event_action
;
2424 gnutls_session_set_ptr(state
->session
, state
);
2425 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2429 /* Register SNI handling; always, even if not in tls_certificate, so that the
2430 expansion variable $tls_sni is always available. */
2432 gnutls_handshake_set_post_client_hello_function(state
->session
,
2433 exim_sni_handling_cb
);
2435 /* Set context and tell client to go ahead, except in the case of TLS startup
2436 on connection, where outputting anything now upsets the clients and tends to
2437 make them disconnect. We need to have an explicit fflush() here, to force out
2438 the response. Other smtp_printf() calls do not need it, because in non-TLS
2439 mode, the fflush() happens when smtp_getc() is called. */
2441 if (!state
->tlsp
->on_connect
)
2443 smtp_printf("220 TLS go ahead\r\n", FALSE
);
2447 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2448 that the GnuTLS library doesn't.
2449 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2450 to set (and clear down afterwards) up a pull-timeout callback function that does
2451 a select, so we're no better off unless avoiding signals becomes an issue. */
2453 gnutls_transport_set_ptr2(state
->session
,
2454 (gnutls_transport_ptr_t
)(long) fileno(smtp_in
),
2455 (gnutls_transport_ptr_t
)(long) fileno(smtp_out
));
2456 state
->fd_in
= fileno(smtp_in
);
2457 state
->fd_out
= fileno(smtp_out
);
2459 sigalrm_seen
= FALSE
;
2460 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2462 rc
= gnutls_handshake(state
->session
);
2463 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
2466 if (rc
!= GNUTLS_E_SUCCESS
)
2468 /* It seems that, except in the case of a timeout, we have to close the
2469 connection right here; otherwise if the other end is running OpenSSL it hangs
2470 until the server times out. */
2474 tls_error(US
"gnutls_handshake", US
"timed out", NULL
, errstr
);
2475 gnutls_db_remove_session(state
->session
);
2479 tls_error_gnu(US
"gnutls_handshake", rc
, NULL
, errstr
);
2480 (void) gnutls_alert_send_appropriate(state
->session
, rc
);
2481 gnutls_deinit(state
->session
);
2482 gnutls_certificate_free_credentials(state
->x509_cred
);
2484 shutdown(state
->fd_out
, SHUT_WR
);
2485 for (int i
= 1024; fgetc(smtp_in
) != EOF
&& i
> 0; ) i
--; /* drain skt */
2486 (void)fclose(smtp_out
);
2487 (void)fclose(smtp_in
);
2488 smtp_out
= smtp_in
= NULL
;
2494 #ifdef EXPERIMENTAL_TLS_RESUME
2495 tls_server_resume_posthandshake(state
);
2498 DEBUG(D_tls
) post_handshake_debug(state
);
2500 /* Verify after the fact */
2502 if (!verify_certificate(state
, errstr
))
2504 if (state
->verify_requirement
!= VERIFY_OPTIONAL
)
2506 (void) tls_error(US
"certificate verification failed", *errstr
, NULL
, errstr
);
2510 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2514 /* Sets various Exim expansion variables; always safe within server */
2516 extract_exim_vars_from_tls_state(state
);
2518 /* TLS has been set up. Adjust the input functions to read via TLS,
2519 and initialize appropriately. */
2521 state
->xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2523 receive_getc
= tls_getc
;
2524 receive_getbuf
= tls_getbuf
;
2525 receive_get_cache
= tls_get_cache
;
2526 receive_ungetc
= tls_ungetc
;
2527 receive_feof
= tls_feof
;
2528 receive_ferror
= tls_ferror
;
2529 receive_smtp_buffered
= tls_smtp_buffered
;
2538 tls_client_setup_hostname_checks(host_item
* host
, exim_gnutls_state_st
* state
,
2539 smtp_transport_options_block
* ob
)
2541 if (verify_check_given_host(CUSS
&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2543 state
->exp_tls_verify_cert_hostnames
=
2545 string_domain_utf8_to_alabel(host
->name
, NULL
);
2550 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2551 state
->exp_tls_verify_cert_hostnames
);
2559 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2560 GnuTLS-DANE's preferred format. Hang it on the state str for later
2561 use in DANE verification.
2563 We point at the dnsa data not copy it, so it must remain valid until
2564 after verification is done.*/
2567 dane_tlsa_load(exim_gnutls_state_st
* state
, dns_answer
* dnsa
)
2571 const char ** dane_data
;
2572 int * dane_data_len
;
2575 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2576 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2577 ) if (rr
->type
== T_TLSA
) i
++;
2579 dane_data
= store_get(i
* sizeof(uschar
*), FALSE
);
2580 dane_data_len
= store_get(i
* sizeof(int), FALSE
);
2583 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2584 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2585 ) if (rr
->type
== T_TLSA
&& rr
->size
> 3)
2587 const uschar
* p
= rr
->data
;
2588 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
2589 uint8_t usage
= p
[0], sel
= p
[1], type
= p
[2];
2592 debug_printf("TLSA: %d %d %d size %d\n", usage
, sel
, type
, rr
->size
);
2594 if ( (usage
!= DANESSL_USAGE_DANE_TA
&& usage
!= DANESSL_USAGE_DANE_EE
)
2595 || (sel
!= 0 && sel
!= 1)
2600 case 0: /* Full: cannot check at present */
2602 case 1: if (rr
->size
!= 3 + 256/8) continue; /* sha2-256 */
2604 case 2: if (rr
->size
!= 3 + 512/8) continue; /* sha2-512 */
2609 tls_out
.tlsa_usage
|= 1<<usage
;
2610 dane_data
[i
] = CS p
;
2611 dane_data_len
[i
++] = rr
->size
;
2614 if (!i
) return FALSE
;
2616 dane_data
[i
] = NULL
;
2617 dane_data_len
[i
] = 0;
2619 state
->dane_data
= (char * const *)dane_data
;
2620 state
->dane_data_len
= dane_data_len
;
2627 #ifdef EXPERIMENTAL_TLS_RESUME
2628 /* On the client, get any stashed session for the given IP from hints db
2629 and apply it to the ssl-connection for attempted resumption. Although
2630 there is a gnutls_session_ticket_enable_client() interface it is
2631 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
2632 by deafult". There seems to be no way to disable them, so even hosts not
2633 enabled by the transport option will be sent a ticket request. We will
2634 however avoid storing and retrieving session information. */
2637 tls_retrieve_session(tls_support
* tlsp
, gnutls_session_t session
,
2638 host_item
* host
, smtp_transport_options_block
* ob
)
2640 tlsp
->resumption
= RESUME_SUPPORTED
;
2641 if (verify_check_given_host(CUSS
&ob
->tls_resumption_hosts
, host
) == OK
)
2643 dbdata_tls_session
* dt
;
2645 open_db dbblock
, * dbm_file
;
2648 debug_printf("check for resumable session for %s\n", host
->address
);
2649 tlsp
->host_resumable
= TRUE
;
2650 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
2651 if ((dbm_file
= dbfn_open(US
"tls", O_RDONLY
, &dbblock
, FALSE
, FALSE
)))
2653 /* Key for the db is the IP. We'd like to filter the retrieved session
2654 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
2656 if ((dt
= dbfn_read_with_length(dbm_file
, host
->address
, &len
)))
2657 if (!(rc
= gnutls_session_set_data(session
,
2658 CUS dt
->session
, (size_t)len
- sizeof(dbdata_tls_session
))))
2660 DEBUG(D_tls
) debug_printf("good session\n");
2661 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
2663 else DEBUG(D_tls
) debug_printf("setting session resumption data: %s\n",
2664 US
gnutls_strerror(rc
));
2665 dbfn_close(dbm_file
);
2672 tls_save_session(tls_support
* tlsp
, gnutls_session_t session
, const host_item
* host
)
2674 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
2675 but this flag is not set until the second. TLS 1.3 it's the other way about.
2676 Keep both calls as the session data cannot be extracted before handshake
2679 if (gnutls_session_get_flags(session
) & GNUTLS_SFLAGS_SESSION_TICKET
)
2684 DEBUG(D_tls
) debug_printf("server offered session ticket\n");
2685 tlsp
->ticket_received
= TRUE
;
2686 tlsp
->resumption
|= RESUME_SERVER_TICKET
;
2688 if (tlsp
->host_resumable
)
2689 if (!(rc
= gnutls_session_get_data2(session
, &tkt
)))
2691 open_db dbblock
, * dbm_file
;
2692 int dlen
= sizeof(dbdata_tls_session
) + tkt
.size
;
2693 dbdata_tls_session
* dt
= store_get(dlen
, TRUE
);
2695 DEBUG(D_tls
) debug_printf("session data size %u\n", (unsigned)tkt
.size
);
2696 memcpy(dt
->session
, tkt
.data
, tkt
.size
);
2697 gnutls_free(tkt
.data
);
2699 if ((dbm_file
= dbfn_open(US
"tls", O_RDWR
, &dbblock
, FALSE
, FALSE
)))
2701 /* key for the db is the IP */
2702 dbfn_delete(dbm_file
, host
->address
);
2703 dbfn_write(dbm_file
, host
->address
, dt
, dlen
);
2704 dbfn_close(dbm_file
);
2707 debug_printf("wrote session db (len %u)\n", (unsigned)dlen
);
2711 debug_printf("extract session data: %s\n", US
gnutls_strerror(rc
));
2716 /* With a TLS1.3 session, the ticket(s) are not seen until
2717 the first data read is attempted. And there's often two of them.
2718 Pick them up with this callback. We are also called for 1.2
2722 tls_client_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
2723 unsigned incoming
, const gnutls_datum_t
* msg
)
2725 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(sess
);
2726 tls_support
* tlsp
= state
->tlsp
;
2728 DEBUG(D_tls
) debug_printf("newticket cb\n");
2730 if (!tlsp
->ticket_received
)
2731 tls_save_session(tlsp
, sess
, state
->host
);
2737 tls_client_resume_prehandshake(exim_gnutls_state_st
* state
,
2738 tls_support
* tlsp
, host_item
* host
,
2739 smtp_transport_options_block
* ob
)
2741 gnutls_session_set_ptr(state
->session
, state
);
2742 gnutls_handshake_set_hook_function(state
->session
,
2743 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
, GNUTLS_HOOK_POST
, tls_client_ticket_cb
);
2745 tls_retrieve_session(tlsp
, state
->session
, host
, ob
);
2749 tls_client_resume_posthandshake(exim_gnutls_state_st
* state
,
2750 tls_support
* tlsp
, host_item
* host
)
2752 if (gnutls_session_is_resumed(state
->session
))
2754 DEBUG(D_tls
) debug_printf("Session resumed\n");
2755 tlsp
->resumption
|= RESUME_USED
;
2758 tls_save_session(tlsp
, state
->session
, host
);
2760 #endif /* EXPERIMENTAL_TLS_RESUME */
2763 /*************************************************
2764 * Start a TLS session in a client *
2765 *************************************************/
2767 /* Called from the smtp transport after STARTTLS has been accepted.
2770 cctx connection context
2771 conn_args connection details
2772 cookie datum for randomness (not used)
2773 tlsp record details of channel configuration here; must be non-NULL
2774 errstr error string pointer
2776 Returns: TRUE for success with TLS session context set in smtp context,
2781 tls_client_start(client_conn_ctx
* cctx
, smtp_connect_args
* conn_args
,
2782 void * cookie ARG_UNUSED
,
2783 tls_support
* tlsp
, uschar
** errstr
)
2785 host_item
* host
= conn_args
->host
; /* for msgs and option-tests */
2786 transport_instance
* tb
= conn_args
->tblock
; /* always smtp or NULL */
2787 smtp_transport_options_block
* ob
= tb
2788 ? (smtp_transport_options_block
*)tb
->options_block
2789 : &smtp_transport_option_defaults
;
2791 exim_gnutls_state_st
* state
= NULL
;
2792 uschar
* cipher_list
= NULL
;
2794 #ifndef DISABLE_OCSP
2796 verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
;
2797 BOOL request_ocsp
= require_ocsp
? TRUE
2798 : verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2801 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx
->sock
);
2804 /* If dane is flagged, have either request or require dane for this host, and
2805 a TLSA record found. Therefore, dane verify required. Which implies cert must
2806 be requested and supplied, dane verify must pass, and cert verify irrelevant
2807 (incl. hostnames), and (caller handled) require_tls */
2809 if (conn_args
->dane
&& ob
->dane_require_tls_ciphers
)
2811 /* not using expand_check_tlsvar because not yet in state */
2812 if (!expand_check(ob
->dane_require_tls_ciphers
, US
"dane_require_tls_ciphers",
2813 &cipher_list
, errstr
))
2815 cipher_list
= cipher_list
&& *cipher_list
2816 ? ob
->dane_require_tls_ciphers
: ob
->tls_require_ciphers
;
2821 cipher_list
= ob
->tls_require_ciphers
;
2823 if (tls_init(host
, ob
->tls_certificate
, ob
->tls_privatekey
,
2824 ob
->tls_sni
, ob
->tls_verify_certificates
, ob
->tls_crl
,
2825 cipher_list
, &state
, tlsp
, errstr
) != OK
)
2829 int dh_min_bits
= ob
->tls_dh_min_bits
;
2830 if (dh_min_bits
< EXIM_CLIENT_DH_MIN_MIN_BITS
)
2833 debug_printf("WARNING: tls_dh_min_bits far too low,"
2834 " clamping %d up to %d\n",
2835 dh_min_bits
, EXIM_CLIENT_DH_MIN_MIN_BITS
);
2836 dh_min_bits
= EXIM_CLIENT_DH_MIN_MIN_BITS
;
2839 DEBUG(D_tls
) debug_printf("Setting D-H prime minimum"
2840 " acceptable bits to %d\n",
2842 gnutls_dh_set_prime_bits(state
->session
, dh_min_bits
);
2845 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2846 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2847 the specified host patterns if one of them is defined */
2850 if (conn_args
->dane
&& dane_tlsa_load(state
, &conn_args
->tlsa_dnsa
))
2853 debug_printf("TLS: server certificate DANE required.\n");
2854 state
->verify_requirement
= VERIFY_DANE
;
2855 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2859 if ( ( state
->exp_tls_verify_certificates
2860 && !ob
->tls_verify_hosts
2861 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2863 || verify_check_given_host(CUSS
&ob
->tls_verify_hosts
, host
) == OK
2866 tls_client_setup_hostname_checks(host
, state
, ob
);
2868 debug_printf("TLS: server certificate verification required.\n");
2869 state
->verify_requirement
= VERIFY_REQUIRED
;
2870 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2872 else if (verify_check_given_host(CUSS
&ob
->tls_try_verify_hosts
, host
) == OK
)
2874 tls_client_setup_hostname_checks(host
, state
, ob
);
2876 debug_printf("TLS: server certificate verification optional.\n");
2877 state
->verify_requirement
= VERIFY_OPTIONAL
;
2878 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2883 debug_printf("TLS: server certificate verification not required.\n");
2884 state
->verify_requirement
= VERIFY_NONE
;
2885 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2888 #ifndef DISABLE_OCSP
2889 /* supported since GnuTLS 3.1.3 */
2892 DEBUG(D_tls
) debug_printf("TLS: will request OCSP stapling\n");
2893 if ((rc
= gnutls_ocsp_status_request_enable_client(state
->session
,
2894 NULL
, 0, NULL
)) != OK
)
2896 tls_error_gnu(US
"cert-status-req", rc
, state
->host
, errstr
);
2899 tlsp
->ocsp
= OCSP_NOT_RESP
;
2903 #ifdef EXPERIMENTAL_TLS_RESUME
2904 tls_client_resume_prehandshake(state
, tlsp
, host
, ob
);
2907 #ifndef DISABLE_EVENT
2908 if (tb
&& tb
->event_action
)
2910 state
->event_action
= tb
->event_action
;
2911 gnutls_session_set_ptr(state
->session
, state
);
2912 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2916 gnutls_transport_set_ptr(state
->session
, (gnutls_transport_ptr_t
)(long) cctx
->sock
);
2917 state
->fd_in
= cctx
->sock
;
2918 state
->fd_out
= cctx
->sock
;
2920 DEBUG(D_tls
) debug_printf("about to gnutls_handshake\n");
2921 /* There doesn't seem to be a built-in timeout on connection. */
2923 sigalrm_seen
= FALSE
;
2924 ALARM(ob
->command_timeout
);
2926 rc
= gnutls_handshake(state
->session
);
2927 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
2930 if (rc
!= GNUTLS_E_SUCCESS
)
2934 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_USER_CANCELED
);
2935 tls_error(US
"gnutls_handshake", US
"timed out", state
->host
, errstr
);
2938 tls_error_gnu(US
"gnutls_handshake", rc
, state
->host
, errstr
);
2942 DEBUG(D_tls
) post_handshake_debug(state
);
2946 if (!verify_certificate(state
, errstr
))
2948 tls_error(US
"certificate verification failed", *errstr
, state
->host
, errstr
);
2952 #ifndef DISABLE_OCSP
2957 gnutls_datum_t stapling
;
2958 gnutls_ocsp_resp_t resp
;
2959 gnutls_datum_t printed
;
2963 # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
2964 (rc
= gnutls_ocsp_status_request_get2(state
->session
, idx
, &stapling
)) == 0;
2966 (rc
= gnutls_ocsp_status_request_get(state
->session
, &stapling
)) == 0;
2969 if ( (rc
= gnutls_ocsp_resp_init(&resp
)) == 0
2970 && (rc
= gnutls_ocsp_resp_import(resp
, &stapling
)) == 0
2971 && (rc
= gnutls_ocsp_resp_print(resp
, GNUTLS_OCSP_PRINT_COMPACT
, &printed
)) == 0
2974 debug_printf("%.4096s", printed
.data
);
2975 gnutls_free(printed
.data
);
2978 (void) tls_error_gnu(US
"ocsp decode", rc
, state
->host
, errstr
);
2980 (void) tls_error_gnu(US
"ocsp decode", rc
, state
->host
, errstr
);
2983 if (gnutls_ocsp_status_request_is_checked(state
->session
, 0) == 0)
2985 tlsp
->ocsp
= OCSP_FAILED
;
2986 tls_error(US
"certificate status check failed", NULL
, state
->host
, errstr
);
2992 DEBUG(D_tls
) debug_printf("Passed OCSP checking\n");
2993 tlsp
->ocsp
= OCSP_VFIED
;
2998 #ifdef EXPERIMENTAL_TLS_RESUME
2999 tls_client_resume_posthandshake(state
, tlsp
, host
);
3002 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
3004 extract_exim_vars_from_tls_state(state
);
3006 cctx
->tls_ctx
= state
;
3013 /*************************************************
3014 * Close down a TLS session *
3015 *************************************************/
3017 /* This is also called from within a delivery subprocess forked from the
3018 daemon, to shut down the TLS library, without actually doing a shutdown (which
3019 would tamper with the TLS session in the parent process).
3022 ct_ctx client context pointer, or NULL for the one global server context
3023 shutdown 1 if TLS close-alert is to be sent,
3024 2 if also response to be waited for
3030 tls_close(void * ct_ctx
, int shutdown
)
3032 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3033 tls_support
* tlsp
= state
->tlsp
;
3035 if (!tlsp
|| tlsp
->active
.sock
< 0) return; /* TLS was not active */
3039 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS%s\n",
3040 shutdown
> 1 ? " (with response-wait)" : "");
3043 gnutls_bye(state
->session
, shutdown
> 1 ? GNUTLS_SHUT_RDWR
: GNUTLS_SHUT_WR
);
3047 if (!ct_ctx
) /* server */
3049 receive_getc
= smtp_getc
;
3050 receive_getbuf
= smtp_getbuf
;
3051 receive_get_cache
= smtp_get_cache
;
3052 receive_ungetc
= smtp_ungetc
;
3053 receive_feof
= smtp_feof
;
3054 receive_ferror
= smtp_ferror
;
3055 receive_smtp_buffered
= smtp_buffered
;
3058 gnutls_deinit(state
->session
);
3059 gnutls_certificate_free_credentials(state
->x509_cred
);
3061 tlsp
->active
.sock
= -1;
3062 tlsp
->active
.tls_ctx
= NULL
;
3063 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3064 tls_channelbinding_b64
= NULL
;
3067 if (state
->xfer_buffer
) store_free(state
->xfer_buffer
);
3068 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
3075 tls_refill(unsigned lim
)
3077 exim_gnutls_state_st
* state
= &state_server
;
3080 DEBUG(D_tls
) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
3081 state
->session
, state
->xfer_buffer
, ssl_xfer_buffer_size
);
3083 sigalrm_seen
= FALSE
;
3084 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
3087 inbytes
= gnutls_record_recv(state
->session
, state
->xfer_buffer
,
3088 MIN(ssl_xfer_buffer_size
, lim
));
3089 while (inbytes
== GNUTLS_E_AGAIN
);
3091 if (smtp_receive_timeout
> 0) ALARM_CLR(0);
3093 if (had_command_timeout
) /* set by signal handler */
3094 smtp_command_timeout_exit(); /* does not return */
3095 if (had_command_sigterm
)
3096 smtp_command_sigterm_exit();
3097 if (had_data_timeout
)
3098 smtp_data_timeout_exit();
3099 if (had_data_sigint
)
3100 smtp_data_sigint_exit();
3102 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3103 TLS session has been closed down, not that the socket itself has been closed
3104 down. Revert to non-TLS handling. */
3108 DEBUG(D_tls
) debug_printf("Got tls read timeout\n");
3109 state
->xfer_error
= TRUE
;
3113 else if (inbytes
== 0)
3115 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
3116 tls_close(NULL
, TLS_NO_SHUTDOWN
);
3120 /* Handle genuine errors */
3122 else if (inbytes
< 0)
3124 DEBUG(D_tls
) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__
);
3125 record_io_error(state
, (int) inbytes
, US
"recv", NULL
);
3126 state
->xfer_error
= TRUE
;
3129 #ifndef DISABLE_DKIM
3130 dkim_exim_verify_feed(state
->xfer_buffer
, inbytes
);
3132 state
->xfer_buffer_hwm
= (int) inbytes
;
3133 state
->xfer_buffer_lwm
= 0;
3137 /*************************************************
3138 * TLS version of getc *
3139 *************************************************/
3141 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3142 it refills the buffer via the GnuTLS reading function.
3143 Only used by the server-side TLS.
3145 This feeds DKIM and should be used for all message-body reads.
3147 Arguments: lim Maximum amount to read/buffer
3148 Returns: the next character or EOF
3152 tls_getc(unsigned lim
)
3154 exim_gnutls_state_st
* state
= &state_server
;
3156 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
3157 if (!tls_refill(lim
))
3158 return state
->xfer_error
? EOF
: smtp_getc(lim
);
3160 /* Something in the buffer; return next uschar */
3162 return state
->xfer_buffer
[state
->xfer_buffer_lwm
++];
3166 tls_getbuf(unsigned * len
)
3168 exim_gnutls_state_st
* state
= &state_server
;
3172 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
3173 if (!tls_refill(*len
))
3175 if (!state
->xfer_error
) return smtp_getbuf(len
);
3180 if ((size
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
) > *len
)
3182 buf
= &state
->xfer_buffer
[state
->xfer_buffer_lwm
];
3183 state
->xfer_buffer_lwm
+= size
;
3192 #ifndef DISABLE_DKIM
3193 exim_gnutls_state_st
* state
= &state_server
;
3194 int n
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
;
3196 dkim_exim_verify_feed(state
->xfer_buffer
+state
->xfer_buffer_lwm
, n
);
3202 tls_could_read(void)
3204 return state_server
.xfer_buffer_lwm
< state_server
.xfer_buffer_hwm
3205 || gnutls_record_check_pending(state_server
.session
) > 0;
3211 /*************************************************
3212 * Read bytes from TLS channel *
3213 *************************************************/
3215 /* This does not feed DKIM, so if the caller uses this for reading message body,
3216 then the caller must feed DKIM.
3219 ct_ctx client context pointer, or NULL for the one global server context
3223 Returns: the number of bytes read
3224 -1 after a failed read, including EOF
3228 tls_read(void * ct_ctx
, uschar
*buff
, size_t len
)
3230 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3236 if (state
->xfer_buffer_lwm
< state
->xfer_buffer_hwm
)
3238 debug_printf("*** PROBABLY A BUG *** " \
3239 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3240 state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
);
3243 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT
")\n",
3244 state
->session
, buff
, len
);
3247 inbytes
= gnutls_record_recv(state
->session
, buff
, len
);
3248 while (inbytes
== GNUTLS_E_AGAIN
);
3250 if (inbytes
> 0) return inbytes
;
3253 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
3257 DEBUG(D_tls
) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__
);
3258 record_io_error(state
, (int)inbytes
, US
"recv", NULL
);
3267 /*************************************************
3268 * Write bytes down TLS channel *
3269 *************************************************/
3273 ct_ctx client context pointer, or NULL for the one global server context
3276 more more data expected soon
3278 Returns: the number of bytes after a successful write,
3279 -1 after a failed write
3283 tls_write(void * ct_ctx
, const uschar
* buff
, size_t len
, BOOL more
)
3287 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3289 static BOOL corked
= FALSE
;
3291 if (more
&& !corked
) gnutls_record_cork(state
->session
);
3294 DEBUG(D_tls
) debug_printf("%s(%p, " SIZE_T_FMT
"%s)\n", __FUNCTION__
,
3295 buff
, left
, more
? ", more" : "");
3299 DEBUG(D_tls
) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT
")\n",
3303 outbytes
= gnutls_record_send(state
->session
, buff
, left
);
3304 while (outbytes
== GNUTLS_E_AGAIN
);
3306 DEBUG(D_tls
) debug_printf("outbytes=" SSIZE_T_FMT
"\n", outbytes
);
3309 DEBUG(D_tls
) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__
);
3310 record_io_error(state
, outbytes
, US
"send", NULL
);
3315 record_io_error(state
, 0, US
"send", US
"TLS channel closed on write");
3326 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT
") than INT_MAX\n",
3334 if (!more
) (void) gnutls_record_uncork(state
->session
, 0);
3345 /*************************************************
3346 * Random number generation *
3347 *************************************************/
3349 /* Pseudo-random number generation. The result is not expected to be
3350 cryptographically strong but not so weak that someone will shoot themselves
3351 in the foot using it as a nonce in input in some email header scheme or
3352 whatever weirdness they'll twist this into. The result should handle fork()
3353 and avoid repeating sequences. OpenSSL handles that for us.
3357 Returns a random number in range [0, max-1]
3360 #ifdef HAVE_GNUTLS_RND
3362 vaguely_random_number(int max
)
3366 uschar smallbuf
[sizeof(r
)];
3371 needed_len
= sizeof(r
);
3372 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3373 asked for a number less than 10. */
3375 for (r
= max
, i
= 0; r
; ++i
)
3381 i
= gnutls_rnd(GNUTLS_RND_NONCE
, smallbuf
, needed_len
);
3384 DEBUG(D_all
) debug_printf("gnutls_rnd() failed, using fallback.\n");
3385 return vaguely_random_number_fallback(max
);
3388 for (uschar
* p
= smallbuf
; needed_len
; --needed_len
, ++p
)
3391 /* We don't particularly care about weighted results; if someone wants
3392 * smooth distribution and cares enough then they should submit a patch then. */
3395 #else /* HAVE_GNUTLS_RND */
3397 vaguely_random_number(int max
)
3399 return vaguely_random_number_fallback(max
);
3401 #endif /* HAVE_GNUTLS_RND */
3406 /*************************************************
3407 * Let tls_require_ciphers be checked at startup *
3408 *************************************************/
3410 /* The tls_require_ciphers option, if set, must be something which the
3413 Returns: NULL on success, or error message
3417 tls_validate_require_cipher(void)
3420 uschar
*expciphers
= NULL
;
3421 gnutls_priority_t priority_cache
;
3423 uschar
* dummy_errstr
;
3425 #ifdef GNUTLS_AUTO_GLOBAL_INIT
3426 # define validate_check_rc(Label) do { \
3427 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \
3428 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3429 # define return_deinit(Label) do { return (Label); } while (0)
3431 # define validate_check_rc(Label) do { \
3432 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3433 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3434 # define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3437 if (exim_gnutls_base_init_done
)
3438 log_write(0, LOG_MAIN
|LOG_PANIC
,
3439 "already initialised GnuTLS, Exim developer bug");
3441 #ifdef HAVE_GNUTLS_PKCS11
3442 if (!gnutls_allow_auto_pkcs11
)
3444 rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
);
3445 validate_check_rc(US
"gnutls_pkcs11_init");
3448 #ifndef GNUTLS_AUTO_GLOBAL_INIT
3449 rc
= gnutls_global_init();
3450 validate_check_rc(US
"gnutls_global_init()");
3452 exim_gnutls_base_init_done
= TRUE
;
3454 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
3455 return_deinit(NULL
);
3457 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
3459 return_deinit(US
"failed to expand tls_require_ciphers");
3461 if (!(expciphers
&& *expciphers
))
3462 return_deinit(NULL
);
3465 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
3467 rc
= gnutls_priority_init(&priority_cache
, CS expciphers
, &errpos
);
3468 validate_check_rc(string_sprintf(
3469 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3470 expciphers
, errpos
- CS expciphers
, errpos
));
3472 #undef return_deinit
3473 #undef validate_check_rc
3474 #ifndef GNUTLS_AUTO_GLOBAL_INIT
3475 gnutls_global_deinit();
3484 /*************************************************
3485 * Report the library versions. *
3486 *************************************************/
3488 /* See a description in tls-openssl.c for an explanation of why this exists.
3490 Arguments: a FILE* to print the results to
3495 tls_version_report(FILE *f
)
3497 fprintf(f
, "Library version: GnuTLS: Compile: %s\n"
3500 gnutls_check_version(NULL
));
3503 #endif /*!MACRO_PREDEF*/
3506 /* End of tls-gnu.c */