1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2017 */
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>
42 /* needed to disable PKCS11 autoload unless requested */
43 #if GNUTLS_VERSION_NUMBER >= 0x020c00
44 # include <gnutls/pkcs11.h>
45 # define SUPPORT_PARAM_TO_PK_BITS
47 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
48 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
51 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
52 # warning "GnuTLS library version too old; tls:cert event unsupported"
53 # define DISABLE_EVENT
55 #if GNUTLS_VERSION_NUMBER >= 0x030306
56 # define SUPPORT_CA_DIR
58 # undef SUPPORT_CA_DIR
60 #if GNUTLS_VERSION_NUMBER >= 0x030014
61 # define SUPPORT_SYSDEFAULT_CABUNDLE
63 #if GNUTLS_VERSION_NUMBER >= 0x030109
66 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
67 # define SUPPORT_SRV_OCSP_STACK
71 # include <gnutls/ocsp.h>
77 gnutls_global_set_audit_log_function()
80 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
83 /* Local static variables for GnuTLS */
85 /* Values for verify_requirement */
87 enum peer_verify_requirement
88 { VERIFY_NONE
, VERIFY_OPTIONAL
, VERIFY_REQUIRED
};
90 /* This holds most state for server or client; with this, we can set up an
91 outbound TLS-enabled connection in an ACL callout, while not stomping all
92 over the TLS variables available for expansion.
94 Some of these correspond to variables in globals.c; those variables will
95 be set to point to content in one of these instances, as appropriate for
96 the stage of the process lifetime.
98 Not handled here: global tls_channelbinding_b64.
101 typedef struct exim_gnutls_state
{
102 gnutls_session_t session
;
103 gnutls_certificate_credentials_t x509_cred
;
104 gnutls_priority_t priority_cache
;
105 enum peer_verify_requirement verify_requirement
;
108 BOOL peer_cert_verified
;
109 BOOL trigger_sni_changes
;
110 BOOL have_set_peerdn
;
111 const struct host_item
*host
;
112 gnutls_x509_crt_t peercert
;
115 uschar
*received_sni
;
117 const uschar
*tls_certificate
;
118 const uschar
*tls_privatekey
;
119 const uschar
*tls_sni
; /* client send only, not received */
120 const uschar
*tls_verify_certificates
;
121 const uschar
*tls_crl
;
122 const uschar
*tls_require_ciphers
;
124 uschar
*exp_tls_certificate
;
125 uschar
*exp_tls_privatekey
;
126 uschar
*exp_tls_verify_certificates
;
128 uschar
*exp_tls_require_ciphers
;
129 const uschar
*exp_tls_verify_cert_hostnames
;
130 #ifndef DISABLE_EVENT
131 uschar
*event_action
;
134 tls_support
*tlsp
; /* set in tls_init() */
141 } exim_gnutls_state_st
;
143 static const exim_gnutls_state_st exim_gnutls_state_init
= {
146 .priority_cache
= NULL
,
147 .verify_requirement
= VERIFY_NONE
,
150 .peer_cert_verified
= FALSE
,
151 .trigger_sni_changes
=FALSE
,
152 .have_set_peerdn
= FALSE
,
157 .received_sni
= NULL
,
159 .tls_certificate
= NULL
,
160 .tls_privatekey
= NULL
,
162 .tls_verify_certificates
= NULL
,
164 .tls_require_ciphers
=NULL
,
166 .exp_tls_certificate
= NULL
,
167 .exp_tls_privatekey
= NULL
,
168 .exp_tls_verify_certificates
= NULL
,
170 .exp_tls_require_ciphers
= NULL
,
171 .exp_tls_verify_cert_hostnames
= NULL
,
172 #ifndef DISABLE_EVENT
173 .event_action
= NULL
,
178 .xfer_buffer_lwm
= 0,
179 .xfer_buffer_hwm
= 0,
184 /* Not only do we have our own APIs which don't pass around state, assuming
185 it's held in globals, GnuTLS doesn't appear to let us register callback data
186 for callbacks, or as part of the session, so we have to keep a "this is the
187 context we're currently dealing with" pointer and rely upon being
188 single-threaded to keep from processing data on an inbound TLS connection while
189 talking to another TLS connection for an outbound check. This does mean that
190 there's no way for heart-beats to be responded to, for the duration of the
192 XXX But see gnutls_session_get_ptr()
195 static exim_gnutls_state_st state_server
, state_client
;
197 /* dh_params are initialised once within the lifetime of a process using TLS;
198 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
199 don't want to repeat this. */
201 static gnutls_dh_params_t dh_server_params
= NULL
;
203 /* No idea how this value was chosen; preserving it. Default is 3600. */
205 static const int ssl_session_timeout
= 200;
207 static const char * const exim_default_gnutls_priority
= "NORMAL";
209 /* Guard library core initialisation */
211 static BOOL exim_gnutls_base_init_done
= FALSE
;
214 static BOOL gnutls_buggy_ocsp
= FALSE
;
218 /* ------------------------------------------------------------------------ */
221 #define MAX_HOST_LEN 255
223 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
224 the library logging; a value less than 0 disables the calls to set up logging
225 callbacks. Possibly GNuTLS also looks for an environment variable
226 "GNUTLS_DEBUG_LEVEL". */
227 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
228 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
231 #ifndef EXIM_CLIENT_DH_MIN_BITS
232 # define EXIM_CLIENT_DH_MIN_BITS 1024
235 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
236 can ask for a bit-strength. Without that, we stick to the constant we had
238 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
239 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
242 #define exim_gnutls_err_check(rc, Label) do { \
243 if ((rc) != GNUTLS_E_SUCCESS) \
244 return tls_error((Label), gnutls_strerror(rc), host, errstr); \
247 #define expand_check_tlsvar(Varname, errstr) \
248 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
250 #if GNUTLS_VERSION_NUMBER >= 0x020c00
251 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
252 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
253 # define HAVE_GNUTLS_RND
254 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
255 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
256 * isn't available sometimes, so this needs to become a conditional
257 * compilation; the sanest way to deal with this being a problem on
258 * older OSes is to block it in the Local/Makefile with this compiler
260 # ifndef AVOID_GNUTLS_PKCS11
261 # define HAVE_GNUTLS_PKCS11
262 # endif /* AVOID_GNUTLS_PKCS11 */
268 /* ------------------------------------------------------------------------ */
269 /* Callback declarations */
271 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
272 static void exim_gnutls_logger_cb(int level
, const char *message
);
275 static int exim_sni_handling_cb(gnutls_session_t session
);
278 static int server_ocsp_stapling_cb(gnutls_session_t session
, void * ptr
,
279 gnutls_datum_t
* ocsp_response
);
284 /* ------------------------------------------------------------------------ */
285 /* Static functions */
287 /*************************************************
289 *************************************************/
291 /* Called from lots of places when errors occur before actually starting to do
292 the TLS handshake, that is, while the session is still in clear. Always returns
293 DEFER for a server and FAIL for a client so that most calls can use "return
294 tls_error(...)" to do this processing and then give an appropriate return. A
295 single function is used for both server and client, because it is called from
296 some shared functions.
299 prefix text to include in the logged error
300 msg additional error string (may be NULL)
301 usually obtained from gnutls_strerror()
302 host NULL if setting up a server;
303 the connected host if setting up a client
304 errstr pointer to returned error string
306 Returns: OK/DEFER/FAIL
310 tls_error(const uschar
*prefix
, const char *msg
, const host_item
*host
,
314 *errstr
= string_sprintf("(%s)%s%s", prefix
, msg
? ": " : "", msg
? msg
: "");
315 return host
? FAIL
: DEFER
;
321 /*************************************************
322 * Deal with logging errors during I/O *
323 *************************************************/
325 /* We have to get the identity of the peer from saved data.
328 state the current GnuTLS exim state container
329 rc the GnuTLS error code, or 0 if it's a local error
330 when text identifying read or write
331 text local error text when ec is 0
337 record_io_error(exim_gnutls_state_st
*state
, int rc
, uschar
*when
, uschar
*text
)
342 if (rc
== GNUTLS_E_FATAL_ALERT_RECEIVED
)
343 msg
= CS
string_sprintf("%s: %s", US
gnutls_strerror(rc
),
344 US
gnutls_alert_get_name(gnutls_alert_get(state
->session
)));
346 msg
= gnutls_strerror(rc
);
348 (void) tls_error(when
, msg
, state
->host
, &errstr
);
351 log_write(0, LOG_MAIN
, "H=%s [%s] TLS error on connection %s",
352 state
->host
->name
, state
->host
->address
, errstr
);
355 uschar
* conn_info
= smtp_get_connection_info();
356 if (Ustrncmp(conn_info
, US
"SMTP ", 5) == 0) conn_info
+= 5;
357 /* I'd like to get separated H= here, but too hard for now */
358 log_write(0, LOG_MAIN
, "TLS error on %s %s", conn_info
, errstr
);
365 /*************************************************
366 * Set various Exim expansion vars *
367 *************************************************/
369 #define exim_gnutls_cert_err(Label) \
372 if (rc != GNUTLS_E_SUCCESS) \
374 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
375 (Label), gnutls_strerror(rc)); \
381 import_cert(const gnutls_datum_t
* cert
, gnutls_x509_crt_t
* crtp
)
385 rc
= gnutls_x509_crt_init(crtp
);
386 exim_gnutls_cert_err(US
"gnutls_x509_crt_init (crt)");
388 rc
= gnutls_x509_crt_import(*crtp
, cert
, GNUTLS_X509_FMT_DER
);
389 exim_gnutls_cert_err(US
"failed to import certificate [gnutls_x509_crt_import(cert)]");
394 #undef exim_gnutls_cert_err
397 /* We set various Exim global variables from the state, once a session has
398 been established. With TLS callouts, may need to change this to stack
399 variables, or just re-call it with the server state after client callout
402 Make sure anything set here is unset in tls_getc().
406 tls_bits strength indicator
407 tls_certificate_verified bool indicator
408 tls_channelbinding_b64 for some SASL mechanisms
410 tls_peercert pointer to library internal
412 tls_sni a (UTF-8) string
413 tls_ourcert pointer to library internal
416 state the relevant exim_gnutls_state_st *
420 extract_exim_vars_from_tls_state(exim_gnutls_state_st
* state
)
422 gnutls_cipher_algorithm_t cipher
;
423 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
426 gnutls_datum_t channel
;
428 tls_support
* tlsp
= state
->tlsp
;
430 tlsp
->active
= state
->fd_out
;
432 cipher
= gnutls_cipher_get(state
->session
);
433 /* returns size in "bytes" */
434 tlsp
->bits
= gnutls_cipher_get_key_size(cipher
) * 8;
436 tlsp
->cipher
= state
->ciphersuite
;
438 DEBUG(D_tls
) debug_printf("cipher: %s\n", state
->ciphersuite
);
440 tlsp
->certificate_verified
= state
->peer_cert_verified
;
442 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
443 only available for use for authenticators while this TLS session is running. */
445 tls_channelbinding_b64
= NULL
;
446 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
449 rc
= gnutls_session_channel_binding(state
->session
, GNUTLS_CB_TLS_UNIQUE
, &channel
);
451 DEBUG(D_tls
) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc
));
453 old_pool
= store_pool
;
454 store_pool
= POOL_PERM
;
455 tls_channelbinding_b64
= b64encode(channel
.data
, (int)channel
.size
);
456 store_pool
= old_pool
;
457 DEBUG(D_tls
) debug_printf("Have channel bindings cached for possible auth usage.\n");
461 /* peercert is set in peer_status() */
462 tlsp
->peerdn
= state
->peerdn
;
463 tlsp
->sni
= state
->received_sni
;
465 /* record our certificate */
467 const gnutls_datum_t
* cert
= gnutls_certificate_get_ours(state
->session
);
468 gnutls_x509_crt_t crt
;
470 tlsp
->ourcert
= cert
&& import_cert(cert
, &crt
)==0 ? crt
: NULL
;
477 /*************************************************
478 * Setup up DH parameters *
479 *************************************************/
481 /* Generating the D-H parameters may take a long time. They only need to
482 be re-generated every so often, depending on security policy. What we do is to
483 keep these parameters in a file in the spool directory. If the file does not
484 exist, we generate them. This means that it is easy to cause a regeneration.
486 The new file is written as a temporary file and renamed, so that an incomplete
487 file is never present. If two processes both compute some new parameters, you
488 waste a bit of effort, but it doesn't seem worth messing around with locking to
491 Returns: OK/DEFER/FAIL
495 init_server_dh(uschar
** errstr
)
498 unsigned int dh_bits
;
500 uschar filename_buf
[PATH_MAX
];
501 uschar
*filename
= NULL
;
503 uschar
*exp_tls_dhparam
;
504 BOOL use_file_in_spool
= FALSE
;
505 BOOL use_fixed_file
= FALSE
;
506 host_item
*host
= NULL
; /* dummy for macros */
508 DEBUG(D_tls
) debug_printf("Initialising GnuTLS server params.\n");
510 rc
= gnutls_dh_params_init(&dh_server_params
);
511 exim_gnutls_err_check(rc
, US
"gnutls_dh_params_init");
516 if (!expand_check(tls_dhparam
, US
"tls_dhparam", &exp_tls_dhparam
, errstr
))
519 if (!exp_tls_dhparam
)
521 DEBUG(D_tls
) debug_printf("Loading default hard-coded DH params\n");
522 m
.data
= US
std_dh_prime_default();
523 m
.size
= Ustrlen(m
.data
);
525 else if (Ustrcmp(exp_tls_dhparam
, "historic") == 0)
526 use_file_in_spool
= TRUE
;
527 else if (Ustrcmp(exp_tls_dhparam
, "none") == 0)
529 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
532 else if (exp_tls_dhparam
[0] != '/')
534 if (!(m
.data
= US
std_dh_prime_named(exp_tls_dhparam
)))
535 return tls_error(US
"No standard prime named", CS exp_tls_dhparam
, NULL
, errstr
);
536 m
.size
= Ustrlen(m
.data
);
540 use_fixed_file
= TRUE
;
541 filename
= exp_tls_dhparam
;
546 rc
= gnutls_dh_params_import_pkcs3(dh_server_params
, &m
, GNUTLS_X509_FMT_PEM
);
547 exim_gnutls_err_check(rc
, US
"gnutls_dh_params_import_pkcs3");
548 DEBUG(D_tls
) debug_printf("Loaded fixed standard D-H parameters\n");
552 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
553 /* If you change this constant, also change dh_param_fn_ext so that we can use a
554 different filename and ensure we have sufficient bits. */
555 dh_bits
= gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH
, GNUTLS_SEC_PARAM_NORMAL
);
557 return tls_error(US
"gnutls_sec_param_to_pk_bits() failed", NULL
, NULL
, errstr
);
559 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
562 dh_bits
= EXIM_SERVER_DH_BITS_PRE2_12
;
564 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
568 /* Some clients have hard-coded limits. */
569 if (dh_bits
> tls_dh_max_bits
)
572 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
574 dh_bits
= tls_dh_max_bits
;
577 if (use_file_in_spool
)
579 if (!string_format(filename_buf
, sizeof(filename_buf
),
580 "%s/gnutls-params-%d", spool_directory
, dh_bits
))
581 return tls_error(US
"overlong filename", NULL
, NULL
, errstr
);
582 filename
= filename_buf
;
585 /* Open the cache file for reading and if successful, read it and set up the
588 if ((fd
= Uopen(filename
, O_RDONLY
, 0)) >= 0)
594 if (fstat(fd
, &statbuf
) < 0) /* EIO */
598 return tls_error(US
"TLS cache stat failed", strerror(saved_errno
), NULL
, errstr
);
600 if (!S_ISREG(statbuf
.st_mode
))
603 return tls_error(US
"TLS cache not a file", NULL
, NULL
, errstr
);
605 if (!(fp
= fdopen(fd
, "rb")))
609 return tls_error(US
"fdopen(TLS cache stat fd) failed",
610 strerror(saved_errno
), NULL
, errstr
);
613 m
.size
= statbuf
.st_size
;
614 if (!(m
.data
= malloc(m
.size
)))
617 return tls_error(US
"malloc failed", strerror(errno
), NULL
, errstr
);
619 if (!(sz
= fread(m
.data
, m
.size
, 1, fp
)))
624 return tls_error(US
"fread failed", strerror(saved_errno
), NULL
, errstr
);
628 rc
= gnutls_dh_params_import_pkcs3(dh_server_params
, &m
, GNUTLS_X509_FMT_PEM
);
630 exim_gnutls_err_check(rc
, US
"gnutls_dh_params_import_pkcs3");
631 DEBUG(D_tls
) debug_printf("read D-H parameters from file \"%s\"\n", filename
);
634 /* If the file does not exist, fall through to compute new data and cache it.
635 If there was any other opening error, it is serious. */
637 else if (errno
== ENOENT
)
641 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename
);
644 return tls_error(string_open_failed(errno
, "\"%s\" for reading", filename
),
647 /* If ret < 0, either the cache file does not exist, or the data it contains
648 is not useful. One particular case of this is when upgrading from an older
649 release of Exim in which the data was stored in a different format. We don't
650 try to be clever and support both formats; we just regenerate new data in this
656 unsigned int dh_bits_gen
= dh_bits
;
658 if ((PATH_MAX
- Ustrlen(filename
)) < 10)
659 return tls_error(US
"Filename too long to generate replacement",
660 CS filename
, NULL
, errstr
);
662 temp_fn
= string_copy(US
"%s.XXXXXXX");
663 if ((fd
= mkstemp(CS temp_fn
)) < 0) /* modifies temp_fn */
664 return tls_error(US
"Unable to open temp file", strerror(errno
), NULL
, errstr
);
665 (void)fchown(fd
, exim_uid
, exim_gid
); /* Probably not necessary */
667 /* GnuTLS overshoots!
668 * If we ask for 2236, we might get 2237 or more.
669 * But there's no way to ask GnuTLS how many bits there really are.
670 * We can ask how many bits were used in a TLS session, but that's it!
671 * The prime itself is hidden behind too much abstraction.
672 * So we ask for less, and proceed on a wing and a prayer.
673 * First attempt, subtracted 3 for 2233 and got 2240.
675 if (dh_bits
>= EXIM_CLIENT_DH_MIN_BITS
+ 10)
677 dh_bits_gen
= dh_bits
- 10;
679 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
684 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
686 rc
= gnutls_dh_params_generate2(dh_server_params
, dh_bits_gen
);
687 exim_gnutls_err_check(rc
, US
"gnutls_dh_params_generate2");
689 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
690 and I confirmed that a NULL call to get the size first is how the GnuTLS
691 sample apps handle this. */
695 rc
= gnutls_dh_params_export_pkcs3(dh_server_params
, GNUTLS_X509_FMT_PEM
,
697 if (rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
698 exim_gnutls_err_check(rc
, US
"gnutls_dh_params_export_pkcs3(NULL) sizing");
700 if (!(m
.data
= malloc(m
.size
)))
701 return tls_error(US
"memory allocation failed", strerror(errno
), NULL
, errstr
);
703 /* this will return a size 1 less than the allocation size above */
704 rc
= gnutls_dh_params_export_pkcs3(dh_server_params
, GNUTLS_X509_FMT_PEM
,
706 if (rc
!= GNUTLS_E_SUCCESS
)
709 exim_gnutls_err_check(rc
, US
"gnutls_dh_params_export_pkcs3() real");
711 m
.size
= sz
; /* shrink by 1, probably */
713 if ((sz
= write_to_fd_buf(fd
, m
.data
, (size_t) m
.size
)) != m
.size
)
716 return tls_error(US
"TLS cache write D-H params failed",
717 strerror(errno
), NULL
, errstr
);
720 if ((sz
= write_to_fd_buf(fd
, US
"\n", 1)) != 1)
721 return tls_error(US
"TLS cache write D-H params final newline failed",
722 strerror(errno
), NULL
, errstr
);
724 if ((rc
= close(fd
)))
725 return tls_error(US
"TLS cache write close() failed", strerror(errno
), NULL
, errstr
);
727 if (Urename(temp_fn
, filename
) < 0)
728 return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"",
729 temp_fn
, filename
), strerror(errno
), NULL
, errstr
);
731 DEBUG(D_tls
) debug_printf("wrote D-H parameters to file \"%s\"\n", filename
);
734 DEBUG(D_tls
) debug_printf("initialized server D-H parameters\n");
741 /* Create and install a selfsigned certificate, for use in server mode */
744 tls_install_selfsign(exim_gnutls_state_st
* state
, uschar
** errstr
)
746 gnutls_x509_crt_t cert
= NULL
;
748 gnutls_x509_privkey_t pkey
= NULL
;
749 const uschar
* where
;
752 where
= US
"initialising pkey";
753 if ((rc
= gnutls_x509_privkey_init(&pkey
))) goto err
;
755 where
= US
"initialising cert";
756 if ((rc
= gnutls_x509_crt_init(&cert
))) goto err
;
758 where
= US
"generating pkey";
759 if ((rc
= gnutls_x509_privkey_generate(pkey
, GNUTLS_PK_RSA
,
760 #ifdef SUPPORT_PARAM_TO_PK_BITS
761 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA
, GNUTLS_SEC_PARAM_LOW
),
768 where
= US
"configuring cert";
770 if ( (rc
= gnutls_x509_crt_set_version(cert
, 3))
771 || (rc
= gnutls_x509_crt_set_serial(cert
, &now
, sizeof(now
)))
772 || (rc
= gnutls_x509_crt_set_activation_time(cert
, now
= time(NULL
)))
773 || (rc
= gnutls_x509_crt_set_expiration_time(cert
, now
+ 60 * 60)) /* 1 hr */
774 || (rc
= gnutls_x509_crt_set_key(cert
, pkey
))
776 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
777 GNUTLS_OID_X520_COUNTRY_NAME
, 0, "UK", 2))
778 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
779 GNUTLS_OID_X520_ORGANIZATION_NAME
, 0, "Exim Developers", 15))
780 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
781 GNUTLS_OID_X520_COMMON_NAME
, 0,
782 smtp_active_hostname
, Ustrlen(smtp_active_hostname
)))
786 where
= US
"signing cert";
787 if ((rc
= gnutls_x509_crt_sign(cert
, cert
, pkey
))) goto err
;
789 where
= US
"installing selfsign cert";
791 if ((rc
= gnutls_certificate_set_x509_key(state
->x509_cred
, &cert
, 1, pkey
)))
797 if (cert
) gnutls_x509_crt_deinit(cert
);
798 if (pkey
) gnutls_x509_privkey_deinit(pkey
);
802 rc
= tls_error(where
, gnutls_strerror(rc
), NULL
, errstr
);
809 /* Add certificate and key, from files.
812 Zero or negative: good. Negate value for certificate index if < 0.
813 Greater than zero: FAIL or DEFER code.
817 tls_add_certfile(exim_gnutls_state_st
* state
, const host_item
* host
,
818 uschar
* certfile
, uschar
* keyfile
, uschar
** errstr
)
820 int rc
= gnutls_certificate_set_x509_key_file(state
->x509_cred
,
821 CS certfile
, CS keyfile
, GNUTLS_X509_FMT_PEM
);
824 string_sprintf("cert/key setup: cert=%s key=%s", certfile
, keyfile
),
825 gnutls_strerror(rc
), host
, errstr
);
830 /*************************************************
831 * Variables re-expanded post-SNI *
832 *************************************************/
834 /* Called from both server and client code, via tls_init(), and also from
835 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
837 We can tell the two apart by state->received_sni being non-NULL in callback.
839 The callback should not call us unless state->trigger_sni_changes is true,
840 which we are responsible for setting on the first pass through.
843 state exim_gnutls_state_st *
844 errstr error string pointer
846 Returns: OK/DEFER/FAIL
850 tls_expand_session_files(exim_gnutls_state_st
* state
, uschar
** errstr
)
854 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
855 uschar
*saved_tls_certificate
= NULL
;
856 uschar
*saved_tls_privatekey
= NULL
;
857 uschar
*saved_tls_verify_certificates
= NULL
;
858 uschar
*saved_tls_crl
= NULL
;
861 /* We check for tls_sni *before* expansion. */
862 if (!host
) /* server */
863 if (!state
->received_sni
)
865 if ( state
->tls_certificate
866 && ( Ustrstr(state
->tls_certificate
, US
"tls_sni")
867 || Ustrstr(state
->tls_certificate
, US
"tls_in_sni")
868 || Ustrstr(state
->tls_certificate
, US
"tls_out_sni")
871 DEBUG(D_tls
) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
872 state
->trigger_sni_changes
= TRUE
;
877 /* useful for debugging */
878 saved_tls_certificate
= state
->exp_tls_certificate
;
879 saved_tls_privatekey
= state
->exp_tls_privatekey
;
880 saved_tls_verify_certificates
= state
->exp_tls_verify_certificates
;
881 saved_tls_crl
= state
->exp_tls_crl
;
884 rc
= gnutls_certificate_allocate_credentials(&state
->x509_cred
);
885 exim_gnutls_err_check(rc
, US
"gnutls_certificate_allocate_credentials");
887 #ifdef SUPPORT_SRV_OCSP_STACK
888 gnutls_certificate_set_flags(state
->x509_cred
, GNUTLS_CERTIFICATE_API_V2
);
891 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
892 state members, assuming consistent naming; and expand_check() returns
893 false if expansion failed, unless expansion was forced to fail. */
895 /* check if we at least have a certificate, before doing expensive
898 if (!expand_check_tlsvar(tls_certificate
, errstr
))
901 /* certificate is mandatory in server, optional in client */
903 if ( !state
->exp_tls_certificate
904 || !*state
->exp_tls_certificate
907 return tls_install_selfsign(state
, errstr
);
909 DEBUG(D_tls
) debug_printf("TLS: no client certificate specified; okay\n");
911 if (state
->tls_privatekey
&& !expand_check_tlsvar(tls_privatekey
, errstr
))
914 /* tls_privatekey is optional, defaulting to same file as certificate */
916 if (state
->tls_privatekey
== NULL
|| *state
->tls_privatekey
== '\0')
918 state
->tls_privatekey
= state
->tls_certificate
;
919 state
->exp_tls_privatekey
= state
->exp_tls_certificate
;
923 if (state
->exp_tls_certificate
&& *state
->exp_tls_certificate
)
925 DEBUG(D_tls
) debug_printf("certificate file = %s\nkey file = %s\n",
926 state
->exp_tls_certificate
, state
->exp_tls_privatekey
);
928 if (state
->received_sni
)
929 if ( Ustrcmp(state
->exp_tls_certificate
, saved_tls_certificate
) == 0
930 && Ustrcmp(state
->exp_tls_privatekey
, saved_tls_privatekey
) == 0
933 DEBUG(D_tls
) debug_printf("TLS SNI: cert and key unchanged\n");
937 DEBUG(D_tls
) debug_printf("TLS SNI: have a changed cert/key pair.\n");
940 if (!host
) /* server */
942 const uschar
* clist
= state
->exp_tls_certificate
;
943 const uschar
* klist
= state
->exp_tls_privatekey
;
944 const uschar
* olist
;
945 int csep
= 0, ksep
= 0, osep
= 0, cnt
= 0;
946 uschar
* cfile
, * kfile
, * ofile
;
949 if (!expand_check(tls_ocsp_file
, US
"tls_ocsp_file", &ofile
, errstr
))
954 while (cfile
= string_nextinlist(&clist
, &csep
, NULL
, 0))
956 if (!(kfile
= string_nextinlist(&klist
, &ksep
, NULL
, 0)))
957 return tls_error(US
"cert/key setup: out of keys", NULL
, host
, errstr
);
958 else if (0 < (rc
= tls_add_certfile(state
, host
, cfile
, kfile
, errstr
)))
962 int gnutls_cert_index
= -rc
;
963 DEBUG(D_tls
) debug_printf("TLS: cert/key %s registered\n", cfile
);
965 /* Set the OCSP stapling server info */
969 if (gnutls_buggy_ocsp
)
972 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
974 else if ((ofile
= string_nextinlist(&olist
, &osep
, NULL
, 0)))
976 /* Use the full callback method for stapling just to get
977 observability. More efficient would be to read the file once only,
978 if it never changed (due to SNI). Would need restart on file update,
979 or watch datestamp. */
981 # ifdef SUPPORT_SRV_OCSP_STACK
982 rc
= gnutls_certificate_set_ocsp_status_request_function2(
983 state
->x509_cred
, gnutls_cert_index
,
984 server_ocsp_stapling_cb
, ofile
);
986 exim_gnutls_err_check(rc
,
987 US
"gnutls_certificate_set_ocsp_status_request_function2");
992 debug_printf("oops; multiple OCSP files not supported\n");
995 gnutls_certificate_set_ocsp_status_request_function(
996 state
->x509_cred
, server_ocsp_stapling_cb
, ofile
);
999 DEBUG(D_tls
) debug_printf("OCSP response file = %s\n", ofile
);
1002 DEBUG(D_tls
) debug_printf("ran out of OCSP response files in list\n");
1008 if (0 < (rc
= tls_add_certfile(state
, host
,
1009 state
->exp_tls_certificate
, state
->exp_tls_privatekey
, errstr
)))
1011 DEBUG(D_tls
) debug_printf("TLS: cert/key registered\n");
1014 } /* tls_certificate */
1017 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1018 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1019 error message is provided. However, if we just refrain from setting anything up
1020 in that case, certificate verification fails, which seems to be the correct
1023 if (state
->tls_verify_certificates
&& *state
->tls_verify_certificates
)
1025 if (!expand_check_tlsvar(tls_verify_certificates
, errstr
))
1027 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1028 if (Ustrcmp(state
->exp_tls_verify_certificates
, "system") == 0)
1029 state
->exp_tls_verify_certificates
= NULL
;
1031 if (state
->tls_crl
&& *state
->tls_crl
)
1032 if (!expand_check_tlsvar(tls_crl
, errstr
))
1035 if (!(state
->exp_tls_verify_certificates
&&
1036 *state
->exp_tls_verify_certificates
))
1039 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1040 /* With no tls_verify_certificates, we ignore tls_crl too */
1047 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1051 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1052 if (Ustrcmp(state
->exp_tls_verify_certificates
, "system") == 0)
1053 cert_count
= gnutls_certificate_set_x509_system_trust(state
->x509_cred
);
1057 if (Ustat(state
->exp_tls_verify_certificates
, &statbuf
) < 0)
1059 log_write(0, LOG_MAIN
|LOG_PANIC
, "could not stat %s "
1060 "(tls_verify_certificates): %s", state
->exp_tls_verify_certificates
,
1065 #ifndef SUPPORT_CA_DIR
1066 /* The test suite passes in /dev/null; we could check for that path explicitly,
1067 but who knows if someone has some weird FIFO which always dumps some certs, or
1068 other weirdness. The thing we really want to check is that it's not a
1069 directory, since while OpenSSL supports that, GnuTLS does not.
1070 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1071 if (S_ISDIR(statbuf
.st_mode
))
1074 debug_printf("verify certificates path is a dir: \"%s\"\n",
1075 state
->exp_tls_verify_certificates
);
1076 log_write(0, LOG_MAIN
|LOG_PANIC
,
1077 "tls_verify_certificates \"%s\" is a directory",
1078 state
->exp_tls_verify_certificates
);
1083 DEBUG(D_tls
) debug_printf("verify certificates = %s size=" OFF_T_FMT
"\n",
1084 state
->exp_tls_verify_certificates
, statbuf
.st_size
);
1086 if (statbuf
.st_size
== 0)
1089 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1095 #ifdef SUPPORT_CA_DIR
1096 (statbuf
.st_mode
& S_IFMT
) == S_IFDIR
1098 gnutls_certificate_set_x509_trust_dir(state
->x509_cred
,
1099 CS state
->exp_tls_verify_certificates
, GNUTLS_X509_FMT_PEM
)
1102 gnutls_certificate_set_x509_trust_file(state
->x509_cred
,
1103 CS state
->exp_tls_verify_certificates
, GNUTLS_X509_FMT_PEM
);
1109 exim_gnutls_err_check(rc
, US
"setting certificate trust");
1111 DEBUG(D_tls
) debug_printf("Added %d certificate authorities.\n", cert_count
);
1113 if (state
->tls_crl
&& *state
->tls_crl
&&
1114 state
->exp_tls_crl
&& *state
->exp_tls_crl
)
1116 DEBUG(D_tls
) debug_printf("loading CRL file = %s\n", state
->exp_tls_crl
);
1117 cert_count
= gnutls_certificate_set_x509_crl_file(state
->x509_cred
,
1118 CS state
->exp_tls_crl
, GNUTLS_X509_FMT_PEM
);
1122 exim_gnutls_err_check(rc
, US
"gnutls_certificate_set_x509_crl_file");
1124 DEBUG(D_tls
) debug_printf("Processed %d CRLs.\n", cert_count
);
1133 /*************************************************
1134 * Set X.509 state variables *
1135 *************************************************/
1137 /* In GnuTLS, the registered cert/key are not replaced by a later
1138 set of a cert/key, so for SNI support we need a whole new x509_cred
1139 structure. Which means various other non-re-expanded pieces of state
1140 need to be re-set in the new struct, so the setting logic is pulled
1144 state exim_gnutls_state_st *
1145 errstr error string pointer
1147 Returns: OK/DEFER/FAIL
1151 tls_set_remaining_x509(exim_gnutls_state_st
*state
, uschar
** errstr
)
1154 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
1156 /* Create D-H parameters, or read them from the cache file. This function does
1157 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1158 client-side params. */
1162 if (!dh_server_params
)
1164 rc
= init_server_dh(errstr
);
1165 if (rc
!= OK
) return rc
;
1167 gnutls_certificate_set_dh_params(state
->x509_cred
, dh_server_params
);
1170 /* Link the credentials to the session. */
1172 rc
= gnutls_credentials_set(state
->session
, GNUTLS_CRD_CERTIFICATE
, state
->x509_cred
);
1173 exim_gnutls_err_check(rc
, US
"gnutls_credentials_set");
1178 /*************************************************
1179 * Initialize for GnuTLS *
1180 *************************************************/
1183 #ifndef DISABLE_OCSP
1186 tls_is_buggy_ocsp(void)
1189 uschar maj
, mid
, mic
;
1191 s
= CUS
gnutls_check_version(NULL
);
1195 while (*s
&& *s
!= '.') s
++;
1196 mid
= atoi(CCS
++s
);
1203 while (*s
&& *s
!= '.') s
++;
1204 mic
= atoi(CCS
++s
);
1205 return mic
<= (mid
== 3 ? 16 : 3);
1214 /* Called from both server and client code. In the case of a server, errors
1215 before actual TLS negotiation return DEFER.
1218 host connected host, if client; NULL if server
1219 certificate certificate file
1220 privatekey private key file
1221 sni TLS SNI to send, sometimes when client; else NULL
1224 require_ciphers tls_require_ciphers setting
1225 caller_state returned state-info structure
1226 errstr error string pointer
1228 Returns: OK/DEFER/FAIL
1233 const host_item
*host
,
1234 const uschar
*certificate
,
1235 const uschar
*privatekey
,
1239 const uschar
*require_ciphers
,
1240 exim_gnutls_state_st
**caller_state
,
1243 exim_gnutls_state_st
*state
;
1248 BOOL want_default_priorities
;
1250 if (!exim_gnutls_base_init_done
)
1252 DEBUG(D_tls
) debug_printf("GnuTLS global init required.\n");
1254 #ifdef HAVE_GNUTLS_PKCS11
1255 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1256 which loads modules from a config file, which sounds good and may be wanted
1257 by some sysadmin, but also means in common configurations that GNOME keyring
1258 environment variables are used and so breaks for users calling mailq.
1259 To prevent this, we init PKCS11 first, which is the documented approach. */
1260 if (!gnutls_allow_auto_pkcs11
)
1262 rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
);
1263 exim_gnutls_err_check(rc
, US
"gnutls_pkcs11_init");
1267 rc
= gnutls_global_init();
1268 exim_gnutls_err_check(rc
, US
"gnutls_global_init");
1270 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1273 gnutls_global_set_log_function(exim_gnutls_logger_cb
);
1274 /* arbitrarily chosen level; bump upto 9 for more */
1275 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL
);
1279 #ifndef DISABLE_OCSP
1280 if (tls_ocsp_file
&& (gnutls_buggy_ocsp
= tls_is_buggy_ocsp()))
1281 log_write(0, LOG_MAIN
, "OCSP unusable with this GnuTLS library version");
1284 exim_gnutls_base_init_done
= TRUE
;
1289 state
= &state_client
;
1290 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1291 state
->tlsp
= &tls_out
;
1292 DEBUG(D_tls
) debug_printf("initialising GnuTLS client session\n");
1293 rc
= gnutls_init(&state
->session
, GNUTLS_CLIENT
);
1297 state
= &state_server
;
1298 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1299 state
->tlsp
= &tls_in
;
1300 DEBUG(D_tls
) debug_printf("initialising GnuTLS server session\n");
1301 rc
= gnutls_init(&state
->session
, GNUTLS_SERVER
);
1303 exim_gnutls_err_check(rc
, US
"gnutls_init");
1307 state
->tls_certificate
= certificate
;
1308 state
->tls_privatekey
= privatekey
;
1309 state
->tls_require_ciphers
= require_ciphers
;
1310 state
->tls_sni
= sni
;
1311 state
->tls_verify_certificates
= cas
;
1312 state
->tls_crl
= crl
;
1314 /* This handles the variables that might get re-expanded after TLS SNI;
1315 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1318 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1319 if ((rc
= tls_expand_session_files(state
, errstr
)) != OK
) return rc
;
1321 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1322 requires a new structure afterwards. */
1324 if ((rc
= tls_set_remaining_x509(state
, errstr
)) != OK
) return rc
;
1326 /* set SNI in client, only */
1329 if (!expand_check(sni
, US
"tls_out_sni", &state
->tlsp
->sni
, errstr
))
1331 if (state
->tlsp
->sni
&& *state
->tlsp
->sni
)
1334 debug_printf("Setting TLS client SNI to \"%s\"\n", state
->tlsp
->sni
);
1335 sz
= Ustrlen(state
->tlsp
->sni
);
1336 rc
= gnutls_server_name_set(state
->session
,
1337 GNUTLS_NAME_DNS
, state
->tlsp
->sni
, sz
);
1338 exim_gnutls_err_check(rc
, US
"gnutls_server_name_set");
1341 else if (state
->tls_sni
)
1342 DEBUG(D_tls
) debug_printf("*** PROBABLY A BUG *** " \
1343 "have an SNI set for a server [%s]\n", state
->tls_sni
);
1345 /* This is the priority string support,
1346 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1347 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1348 This was backwards incompatible, but means Exim no longer needs to track
1349 all algorithms and provide string forms for them. */
1351 want_default_priorities
= TRUE
;
1353 if (state
->tls_require_ciphers
&& *state
->tls_require_ciphers
)
1355 if (!expand_check_tlsvar(tls_require_ciphers
, errstr
))
1357 if (state
->exp_tls_require_ciphers
&& *state
->exp_tls_require_ciphers
)
1359 DEBUG(D_tls
) debug_printf("GnuTLS session cipher/priority \"%s\"\n",
1360 state
->exp_tls_require_ciphers
);
1362 rc
= gnutls_priority_init(&state
->priority_cache
,
1363 CS state
->exp_tls_require_ciphers
, &errpos
);
1364 want_default_priorities
= FALSE
;
1365 p
= state
->exp_tls_require_ciphers
;
1368 if (want_default_priorities
)
1371 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n",
1372 exim_default_gnutls_priority
);
1373 rc
= gnutls_priority_init(&state
->priority_cache
,
1374 exim_default_gnutls_priority
, &errpos
);
1375 p
= US exim_default_gnutls_priority
;
1378 exim_gnutls_err_check(rc
, string_sprintf(
1379 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1380 p
, errpos
- CS p
, errpos
));
1382 rc
= gnutls_priority_set(state
->session
, state
->priority_cache
);
1383 exim_gnutls_err_check(rc
, US
"gnutls_priority_set");
1385 gnutls_db_set_cache_expiration(state
->session
, ssl_session_timeout
);
1387 /* Reduce security in favour of increased compatibility, if the admin
1388 decides to make that trade-off. */
1389 if (gnutls_compat_mode
)
1391 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1392 DEBUG(D_tls
) debug_printf("lowering GnuTLS security, compatibility mode\n");
1393 gnutls_session_enable_compatibility_mode(state
->session
);
1395 DEBUG(D_tls
) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1399 *caller_state
= state
;
1405 /*************************************************
1406 * Extract peer information *
1407 *************************************************/
1409 /* Called from both server and client code.
1410 Only this is allowed to set state->peerdn and state->have_set_peerdn
1411 and we use that to detect double-calls.
1413 NOTE: the state blocks last while the TLS connection is up, which is fine
1414 for logging in the server side, but for the client side, we log after teardown
1415 in src/deliver.c. While the session is up, we can twist about states and
1416 repoint tls_* globals, but those variables used for logging or other variable
1417 expansion that happens _after_ delivery need to have a longer life-time.
1419 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1420 doing this more than once per generation of a state context. We set them in
1421 the state context, and repoint tls_* to them. After the state goes away, the
1422 tls_* copies of the pointers remain valid and client delivery logging is happy.
1424 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1428 state exim_gnutls_state_st *
1429 errstr pointer to error string
1431 Returns: OK/DEFER/FAIL
1435 peer_status(exim_gnutls_state_st
*state
, uschar
** errstr
)
1437 uschar cipherbuf
[256];
1438 const gnutls_datum_t
*cert_list
;
1440 unsigned int cert_list_size
= 0;
1441 gnutls_protocol_t protocol
;
1442 gnutls_cipher_algorithm_t cipher
;
1443 gnutls_kx_algorithm_t kx
;
1444 gnutls_mac_algorithm_t mac
;
1445 gnutls_certificate_type_t ct
;
1446 gnutls_x509_crt_t crt
;
1450 if (state
->have_set_peerdn
)
1452 state
->have_set_peerdn
= TRUE
;
1454 state
->peerdn
= NULL
;
1457 cipher
= gnutls_cipher_get(state
->session
);
1458 protocol
= gnutls_protocol_get_version(state
->session
);
1459 mac
= gnutls_mac_get(state
->session
);
1460 kx
= gnutls_kx_get(state
->session
);
1462 string_format(cipherbuf
, sizeof(cipherbuf
),
1464 gnutls_protocol_get_name(protocol
),
1465 gnutls_cipher_suite_get_name(kx
, cipher
, mac
),
1466 (int) gnutls_cipher_get_key_size(cipher
) * 8);
1468 /* I don't see a way that spaces could occur, in the current GnuTLS
1469 code base, but it was a concern in the old code and perhaps older GnuTLS
1470 releases did return "TLS 1.0"; play it safe, just in case. */
1471 for (p
= cipherbuf
; *p
!= '\0'; ++p
)
1474 old_pool
= store_pool
;
1475 store_pool
= POOL_PERM
;
1476 state
->ciphersuite
= string_copy(cipherbuf
);
1477 store_pool
= old_pool
;
1478 state
->tlsp
->cipher
= state
->ciphersuite
;
1481 cert_list
= gnutls_certificate_get_peers(state
->session
, &cert_list_size
);
1483 if (cert_list
== NULL
|| cert_list_size
== 0)
1485 DEBUG(D_tls
) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1486 cert_list
, cert_list_size
);
1487 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1488 return tls_error(US
"certificate verification failed",
1489 "no certificate received from peer", state
->host
, errstr
);
1493 ct
= gnutls_certificate_type_get(state
->session
);
1494 if (ct
!= GNUTLS_CRT_X509
)
1496 const char *ctn
= gnutls_certificate_type_get_name(ct
);
1498 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn
);
1499 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1500 return tls_error(US
"certificate verification not possible, unhandled type",
1501 ctn
, state
->host
, errstr
);
1505 #define exim_gnutls_peer_err(Label) \
1507 if (rc != GNUTLS_E_SUCCESS) \
1509 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1510 (Label), gnutls_strerror(rc)); \
1511 if (state->verify_requirement >= VERIFY_REQUIRED) \
1512 return tls_error((Label), gnutls_strerror(rc), state->host, errstr); \
1517 rc
= import_cert(&cert_list
[0], &crt
);
1518 exim_gnutls_peer_err(US
"cert 0");
1520 state
->tlsp
->peercert
= state
->peercert
= crt
;
1523 rc
= gnutls_x509_crt_get_dn(crt
, NULL
, &sz
);
1524 if (rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
1526 exim_gnutls_peer_err(US
"getting size for cert DN failed");
1527 return FAIL
; /* should not happen */
1529 dn_buf
= store_get_perm(sz
);
1530 rc
= gnutls_x509_crt_get_dn(crt
, CS dn_buf
, &sz
);
1531 exim_gnutls_peer_err(US
"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1533 state
->peerdn
= dn_buf
;
1536 #undef exim_gnutls_peer_err
1542 /*************************************************
1543 * Verify peer certificate *
1544 *************************************************/
1546 /* Called from both server and client code.
1547 *Should* be using a callback registered with
1548 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1549 the peer information, but that's too new for some OSes.
1552 state exim_gnutls_state_st *
1553 errstr where to put an error message
1556 FALSE if the session should be rejected
1557 TRUE if the cert is okay or we just don't care
1561 verify_certificate(exim_gnutls_state_st
*state
, uschar
** errstr
)
1564 unsigned int verify
;
1568 if ((rc
= peer_status(state
, errstr
)) != OK
)
1570 verify
= GNUTLS_CERT_INVALID
;
1571 *errstr
= US
"certificate not supplied";
1574 rc
= gnutls_certificate_verify_peers2(state
->session
, &verify
);
1576 /* Handle the result of verification. INVALID seems to be set as well
1577 as REVOKED, but leave the test for both. */
1580 verify
& (GNUTLS_CERT_INVALID
|GNUTLS_CERT_REVOKED
)
1583 state
->peer_cert_verified
= FALSE
;
1585 *errstr
= verify
& GNUTLS_CERT_REVOKED
1586 ? US
"certificate revoked" : US
"certificate invalid";
1589 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1590 *errstr
, state
->peerdn
? state
->peerdn
: US
"<unset>");
1592 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1594 gnutls_alert_send(state
->session
,
1595 GNUTLS_AL_FATAL
, GNUTLS_A_BAD_CERTIFICATE
);
1599 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1604 if (state
->exp_tls_verify_cert_hostnames
)
1607 const uschar
* list
= state
->exp_tls_verify_cert_hostnames
;
1609 while ((name
= string_nextinlist(&list
, &sep
, NULL
, 0)))
1610 if (gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
, CS name
))
1615 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1616 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1618 gnutls_alert_send(state
->session
,
1619 GNUTLS_AL_FATAL
, GNUTLS_A_BAD_CERTIFICATE
);
1625 state
->peer_cert_verified
= TRUE
;
1626 DEBUG(D_tls
) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1627 state
->peerdn
? state
->peerdn
: US
"<unset>");
1630 state
->tlsp
->peerdn
= state
->peerdn
;
1638 /* ------------------------------------------------------------------------ */
1641 /* Logging function which can be registered with
1642 * gnutls_global_set_log_function()
1643 * gnutls_global_set_log_level() 0..9
1645 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1647 exim_gnutls_logger_cb(int level
, const char *message
)
1649 size_t len
= strlen(message
);
1652 DEBUG(D_tls
) debug_printf("GnuTLS<%d> empty debug message\n", level
);
1655 DEBUG(D_tls
) debug_printf("GnuTLS<%d>: %s%s", level
, message
,
1656 message
[len
-1] == '\n' ? "" : "\n");
1661 /* Called after client hello, should handle SNI work.
1662 This will always set tls_sni (state->received_sni) if available,
1663 and may trigger presenting different certificates,
1664 if state->trigger_sni_changes is TRUE.
1666 Should be registered with
1667 gnutls_handshake_set_post_client_hello_function()
1669 "This callback must return 0 on success or a gnutls error code to terminate the
1672 For inability to get SNI information, we return 0.
1673 We only return non-zero if re-setup failed.
1674 Only used for server-side TLS.
1678 exim_sni_handling_cb(gnutls_session_t session
)
1680 char sni_name
[MAX_HOST_LEN
];
1681 size_t data_len
= MAX_HOST_LEN
;
1682 exim_gnutls_state_st
*state
= &state_server
;
1683 unsigned int sni_type
;
1685 uschar
* dummy_errstr
;
1687 rc
= gnutls_server_name_get(session
, sni_name
, &data_len
, &sni_type
, 0);
1688 if (rc
!= GNUTLS_E_SUCCESS
)
1691 if (rc
== GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
)
1692 debug_printf("TLS: no SNI presented in handshake.\n");
1694 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
1695 gnutls_strerror(rc
), rc
);
1700 if (sni_type
!= GNUTLS_NAME_DNS
)
1702 DEBUG(D_tls
) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type
);
1706 /* We now have a UTF-8 string in sni_name */
1707 old_pool
= store_pool
;
1708 store_pool
= POOL_PERM
;
1709 state
->received_sni
= string_copyn(US sni_name
, data_len
);
1710 store_pool
= old_pool
;
1712 /* We set this one now so that variable expansions below will work */
1713 state
->tlsp
->sni
= state
->received_sni
;
1715 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name
,
1716 state
->trigger_sni_changes
? "" : " (unused for certificate selection)");
1718 if (!state
->trigger_sni_changes
)
1721 if ((rc
= tls_expand_session_files(state
, &dummy_errstr
)) != OK
)
1723 /* If the setup of certs/etc failed before handshake, TLS would not have
1724 been offered. The best we can do now is abort. */
1725 return GNUTLS_E_APPLICATION_ERROR_MIN
;
1728 rc
= tls_set_remaining_x509(state
, &dummy_errstr
);
1729 if (rc
!= OK
) return GNUTLS_E_APPLICATION_ERROR_MIN
;
1736 #ifndef DISABLE_OCSP
1739 server_ocsp_stapling_cb(gnutls_session_t session
, void * ptr
,
1740 gnutls_datum_t
* ocsp_response
)
1743 DEBUG(D_tls
) debug_printf("OCSP stapling callback: %s\n", US ptr
);
1745 if ((ret
= gnutls_load_file(ptr
, ocsp_response
)) < 0)
1747 DEBUG(D_tls
) debug_printf("Failed to load ocsp stapling file %s\n",
1749 tls_in
.ocsp
= OCSP_NOT_RESP
;
1750 return GNUTLS_E_NO_CERTIFICATE_STATUS
;
1753 tls_in
.ocsp
= OCSP_VFY_NOT_TRIED
;
1760 #ifndef DISABLE_EVENT
1762 We use this callback to get observability and detail-level control
1763 for an exim TLS connection (either direction), raising a tls:cert event
1764 for each cert in the chain presented by the peer. Any event
1765 can deny verification.
1767 Return 0 for the handshake to continue or non-zero to terminate.
1771 verify_cb(gnutls_session_t session
)
1773 const gnutls_datum_t
* cert_list
;
1774 unsigned int cert_list_size
= 0;
1775 gnutls_x509_crt_t crt
;
1778 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(session
);
1780 cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
);
1782 while (cert_list_size
--)
1784 rc
= import_cert(&cert_list
[cert_list_size
], &crt
);
1785 if (rc
!= GNUTLS_E_SUCCESS
)
1787 DEBUG(D_tls
) debug_printf("TLS: peer cert problem: depth %d: %s\n",
1788 cert_list_size
, gnutls_strerror(rc
));
1792 state
->tlsp
->peercert
= crt
;
1793 if ((yield
= event_raise(state
->event_action
,
1794 US
"tls:cert", string_sprintf("%d", cert_list_size
))))
1796 log_write(0, LOG_MAIN
,
1797 "SSL verify denied by event-action: depth=%d: %s",
1798 cert_list_size
, yield
);
1799 return 1; /* reject */
1801 state
->tlsp
->peercert
= NULL
;
1811 /* ------------------------------------------------------------------------ */
1812 /* Exported functions */
1817 /*************************************************
1818 * Start a TLS session in a server *
1819 *************************************************/
1821 /* This is called when Exim is running as a server, after having received
1822 the STARTTLS command. It must respond to that command, and then negotiate
1826 require_ciphers list of allowed ciphers or NULL
1827 errstr pointer to error string
1829 Returns: OK on success
1830 DEFER for errors before the start of the negotiation
1831 FAIL for errors during the negotiation; the server can't
1836 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
1839 exim_gnutls_state_st
* state
= NULL
;
1841 /* Check for previous activation */
1842 if (tls_in
.active
>= 0)
1844 tls_error(US
"STARTTLS received after TLS started", "", NULL
, errstr
);
1845 smtp_printf("554 Already in TLS\r\n", FALSE
);
1849 /* Initialize the library. If it fails, it will already have logged the error
1850 and sent an SMTP response. */
1852 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a server\n");
1854 if ((rc
= tls_init(NULL
, tls_certificate
, tls_privatekey
,
1855 NULL
, tls_verify_certificates
, tls_crl
,
1856 require_ciphers
, &state
, errstr
)) != OK
) return rc
;
1858 /* If this is a host for which certificate verification is mandatory or
1859 optional, set up appropriately. */
1861 if (verify_check_host(&tls_verify_hosts
) == OK
)
1864 debug_printf("TLS: a client certificate will be required.\n");
1865 state
->verify_requirement
= VERIFY_REQUIRED
;
1866 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
1868 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
1871 debug_printf("TLS: a client certificate will be requested but not required.\n");
1872 state
->verify_requirement
= VERIFY_OPTIONAL
;
1873 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
1878 debug_printf("TLS: a client certificate will not be requested.\n");
1879 state
->verify_requirement
= VERIFY_NONE
;
1880 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
1883 #ifndef DISABLE_EVENT
1886 state
->event_action
= event_action
;
1887 gnutls_session_set_ptr(state
->session
, state
);
1888 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
1892 /* Register SNI handling; always, even if not in tls_certificate, so that the
1893 expansion variable $tls_sni is always available. */
1895 gnutls_handshake_set_post_client_hello_function(state
->session
,
1896 exim_sni_handling_cb
);
1898 /* Set context and tell client to go ahead, except in the case of TLS startup
1899 on connection, where outputting anything now upsets the clients and tends to
1900 make them disconnect. We need to have an explicit fflush() here, to force out
1901 the response. Other smtp_printf() calls do not need it, because in non-TLS
1902 mode, the fflush() happens when smtp_getc() is called. */
1904 if (!state
->tlsp
->on_connect
)
1906 smtp_printf("220 TLS go ahead\r\n", FALSE
);
1910 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1911 that the GnuTLS library doesn't. */
1913 gnutls_transport_set_ptr2(state
->session
,
1914 (gnutls_transport_ptr_t
)(long) fileno(smtp_in
),
1915 (gnutls_transport_ptr_t
)(long) fileno(smtp_out
));
1916 state
->fd_in
= fileno(smtp_in
);
1917 state
->fd_out
= fileno(smtp_out
);
1919 sigalrm_seen
= FALSE
;
1920 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
1922 rc
= gnutls_handshake(state
->session
);
1923 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
1926 if (rc
!= GNUTLS_E_SUCCESS
)
1928 /* It seems that, except in the case of a timeout, we have to close the
1929 connection right here; otherwise if the other end is running OpenSSL it hangs
1930 until the server times out. */
1934 tls_error(US
"gnutls_handshake", "timed out", NULL
, errstr
);
1935 gnutls_db_remove_session(state
->session
);
1939 tls_error(US
"gnutls_handshake", gnutls_strerror(rc
), NULL
, errstr
);
1940 (void) gnutls_alert_send_appropriate(state
->session
, rc
);
1941 gnutls_deinit(state
->session
);
1942 gnutls_certificate_free_credentials(state
->x509_cred
);
1944 shutdown(state
->fd_out
, SHUT_WR
);
1945 for (rc
= 1024; fgetc(smtp_in
) != EOF
&& rc
> 0; ) rc
--; /* drain skt */
1946 (void)fclose(smtp_out
);
1947 (void)fclose(smtp_in
);
1948 smtp_out
= smtp_in
= NULL
;
1954 DEBUG(D_tls
) debug_printf("gnutls_handshake was successful\n");
1956 /* Verify after the fact */
1958 if ( state
->verify_requirement
!= VERIFY_NONE
1959 && !verify_certificate(state
, errstr
))
1961 if (state
->verify_requirement
!= VERIFY_OPTIONAL
)
1963 (void) tls_error(US
"certificate verification failed", *errstr
, NULL
, errstr
);
1967 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
1971 /* Figure out peer DN, and if authenticated, etc. */
1973 if ((rc
= peer_status(state
, NULL
)) != OK
) return rc
;
1975 /* Sets various Exim expansion variables; always safe within server */
1977 extract_exim_vars_from_tls_state(state
);
1979 /* TLS has been set up. Adjust the input functions to read via TLS,
1980 and initialize appropriately. */
1982 state
->xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
1984 receive_getc
= tls_getc
;
1985 receive_getbuf
= tls_getbuf
;
1986 receive_get_cache
= tls_get_cache
;
1987 receive_ungetc
= tls_ungetc
;
1988 receive_feof
= tls_feof
;
1989 receive_ferror
= tls_ferror
;
1990 receive_smtp_buffered
= tls_smtp_buffered
;
1999 tls_client_setup_hostname_checks(host_item
* host
, exim_gnutls_state_st
* state
,
2000 smtp_transport_options_block
* ob
)
2002 if (verify_check_given_host(&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2004 state
->exp_tls_verify_cert_hostnames
=
2006 string_domain_utf8_to_alabel(host
->name
, NULL
);
2011 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2012 state
->exp_tls_verify_cert_hostnames
);
2017 /*************************************************
2018 * Start a TLS session in a client *
2019 *************************************************/
2021 /* Called from the smtp transport after STARTTLS has been accepted.
2024 fd the fd of the connection
2025 host connected host (for messages)
2026 addr the first address (not used)
2027 tb transport (always smtp)
2029 errstr error string pointer
2031 Returns: OK/DEFER/FAIL (because using common functions),
2032 but for a client, DEFER and FAIL have the same meaning
2036 tls_client_start(int fd
, host_item
*host
,
2037 address_item
*addr ARG_UNUSED
,
2038 transport_instance
* tb
,
2039 #ifdef EXPERIMENTAL_DANE
2040 dns_answer
* tlsa_dnsa ARG_UNUSED
,
2044 smtp_transport_options_block
*ob
=
2045 (smtp_transport_options_block
*)tb
->options_block
;
2047 exim_gnutls_state_st
*state
= NULL
;
2048 #ifndef DISABLE_OCSP
2050 verify_check_given_host(&ob
->hosts_require_ocsp
, host
) == OK
;
2051 BOOL request_ocsp
= require_ocsp
? TRUE
2052 : verify_check_given_host(&ob
->hosts_request_ocsp
, host
) == OK
;
2055 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a client on fd %d\n", fd
);
2057 if ((rc
= tls_init(host
, ob
->tls_certificate
, ob
->tls_privatekey
,
2058 ob
->tls_sni
, ob
->tls_verify_certificates
, ob
->tls_crl
,
2059 ob
->tls_require_ciphers
, &state
, errstr
)) != OK
)
2063 int dh_min_bits
= ob
->tls_dh_min_bits
;
2064 if (dh_min_bits
< EXIM_CLIENT_DH_MIN_MIN_BITS
)
2067 debug_printf("WARNING: tls_dh_min_bits far too low,"
2068 " clamping %d up to %d\n",
2069 dh_min_bits
, EXIM_CLIENT_DH_MIN_MIN_BITS
);
2070 dh_min_bits
= EXIM_CLIENT_DH_MIN_MIN_BITS
;
2073 DEBUG(D_tls
) debug_printf("Setting D-H prime minimum"
2074 " acceptable bits to %d\n",
2076 gnutls_dh_set_prime_bits(state
->session
, dh_min_bits
);
2079 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2080 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2081 the specified host patterns if one of them is defined */
2083 if ( ( state
->exp_tls_verify_certificates
2084 && !ob
->tls_verify_hosts
2085 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2087 || verify_check_given_host(&ob
->tls_verify_hosts
, host
) == OK
2090 tls_client_setup_hostname_checks(host
, state
, ob
);
2092 debug_printf("TLS: server certificate verification required.\n");
2093 state
->verify_requirement
= VERIFY_REQUIRED
;
2094 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2096 else if (verify_check_given_host(&ob
->tls_try_verify_hosts
, host
) == OK
)
2098 tls_client_setup_hostname_checks(host
, state
, ob
);
2100 debug_printf("TLS: server certificate verification optional.\n");
2101 state
->verify_requirement
= VERIFY_OPTIONAL
;
2102 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2107 debug_printf("TLS: server certificate verification not required.\n");
2108 state
->verify_requirement
= VERIFY_NONE
;
2109 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2112 #ifndef DISABLE_OCSP
2113 /* supported since GnuTLS 3.1.3 */
2116 DEBUG(D_tls
) debug_printf("TLS: will request OCSP stapling\n");
2117 if ((rc
= gnutls_ocsp_status_request_enable_client(state
->session
,
2118 NULL
, 0, NULL
)) != OK
)
2119 return tls_error(US
"cert-status-req",
2120 gnutls_strerror(rc
), state
->host
, errstr
);
2121 tls_out
.ocsp
= OCSP_NOT_RESP
;
2125 #ifndef DISABLE_EVENT
2126 if (tb
->event_action
)
2128 state
->event_action
= tb
->event_action
;
2129 gnutls_session_set_ptr(state
->session
, state
);
2130 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2134 gnutls_transport_set_ptr(state
->session
, (gnutls_transport_ptr_t
)(long) fd
);
2138 DEBUG(D_tls
) debug_printf("about to gnutls_handshake\n");
2139 /* There doesn't seem to be a built-in timeout on connection. */
2141 sigalrm_seen
= FALSE
;
2142 alarm(ob
->command_timeout
);
2145 rc
= gnutls_handshake(state
->session
);
2146 } while ((rc
== GNUTLS_E_AGAIN
) ||
2147 (rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
));
2150 if (rc
!= GNUTLS_E_SUCCESS
)
2153 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_USER_CANCELED
);
2154 return tls_error(US
"gnutls_handshake", "timed out", state
->host
, errstr
);
2157 return tls_error(US
"gnutls_handshake", gnutls_strerror(rc
), state
->host
, errstr
);
2159 DEBUG(D_tls
) debug_printf("gnutls_handshake was successful\n");
2163 if (state
->verify_requirement
!= VERIFY_NONE
&&
2164 !verify_certificate(state
, errstr
))
2165 return tls_error(US
"certificate verification failed", *errstr
, state
->host
, errstr
);
2167 #ifndef DISABLE_OCSP
2172 gnutls_datum_t stapling
;
2173 gnutls_ocsp_resp_t resp
;
2174 gnutls_datum_t printed
;
2175 if ( (rc
= gnutls_ocsp_status_request_get(state
->session
, &stapling
)) == 0
2176 && (rc
= gnutls_ocsp_resp_init(&resp
)) == 0
2177 && (rc
= gnutls_ocsp_resp_import(resp
, &stapling
)) == 0
2178 && (rc
= gnutls_ocsp_resp_print(resp
, GNUTLS_OCSP_PRINT_FULL
, &printed
)) == 0
2181 debug_printf("%.4096s", printed
.data
);
2182 gnutls_free(printed
.data
);
2185 (void) tls_error(US
"ocsp decode", gnutls_strerror(rc
), state
->host
, errstr
);
2188 if (gnutls_ocsp_status_request_is_checked(state
->session
, 0) == 0)
2190 tls_out
.ocsp
= OCSP_FAILED
;
2191 return tls_error(US
"certificate status check failed", NULL
, state
->host
, errstr
);
2193 DEBUG(D_tls
) debug_printf("Passed OCSP checking\n");
2194 tls_out
.ocsp
= OCSP_VFIED
;
2198 /* Figure out peer DN, and if authenticated, etc. */
2200 if ((rc
= peer_status(state
, errstr
)) != OK
)
2203 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2205 extract_exim_vars_from_tls_state(state
);
2213 /*************************************************
2214 * Close down a TLS session *
2215 *************************************************/
2217 /* This is also called from within a delivery subprocess forked from the
2218 daemon, to shut down the TLS library, without actually doing a shutdown (which
2219 would tamper with the TLS session in the parent process).
2221 Arguments: TRUE if gnutls_bye is to be called
2226 tls_close(BOOL is_server
, BOOL shutdown
)
2228 exim_gnutls_state_st
*state
= is_server
? &state_server
: &state_client
;
2230 if (!state
->tlsp
|| state
->tlsp
->active
< 0) return; /* TLS was not active */
2234 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS\n");
2235 gnutls_bye(state
->session
, GNUTLS_SHUT_WR
);
2238 gnutls_deinit(state
->session
);
2239 gnutls_certificate_free_credentials(state
->x509_cred
);
2242 state
->tlsp
->active
= -1;
2243 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
2245 if ((state_server
.session
== NULL
) && (state_client
.session
== NULL
))
2247 gnutls_global_deinit();
2248 exim_gnutls_base_init_done
= FALSE
;
2256 tls_refill(unsigned lim
)
2258 exim_gnutls_state_st
* state
= &state_server
;
2261 DEBUG(D_tls
) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2262 state
->session
, state
->xfer_buffer
, ssl_xfer_buffer_size
);
2264 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
2265 inbytes
= gnutls_record_recv(state
->session
, state
->xfer_buffer
,
2266 MIN(ssl_xfer_buffer_size
, lim
));
2269 /* Timeouts do not get this far; see command_timeout_handler().
2270 A zero-byte return appears to mean that the TLS session has been
2271 closed down, not that the socket itself has been closed down. Revert to
2272 non-TLS handling. */
2276 DEBUG(D_tls
) debug_printf("Got tls read timeout\n");
2277 state
->xfer_error
= 1;
2281 else if (inbytes
== 0)
2283 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
2285 receive_getc
= smtp_getc
;
2286 receive_getbuf
= smtp_getbuf
;
2287 receive_get_cache
= smtp_get_cache
;
2288 receive_ungetc
= smtp_ungetc
;
2289 receive_feof
= smtp_feof
;
2290 receive_ferror
= smtp_ferror
;
2291 receive_smtp_buffered
= smtp_buffered
;
2293 gnutls_deinit(state
->session
);
2294 gnutls_certificate_free_credentials(state
->x509_cred
);
2296 state
->session
= NULL
;
2297 state
->tlsp
->active
= -1;
2298 state
->tlsp
->bits
= 0;
2299 state
->tlsp
->certificate_verified
= FALSE
;
2300 tls_channelbinding_b64
= NULL
;
2301 state
->tlsp
->cipher
= NULL
;
2302 state
->tlsp
->peercert
= NULL
;
2303 state
->tlsp
->peerdn
= NULL
;
2308 /* Handle genuine errors */
2310 else if (inbytes
< 0)
2312 record_io_error(state
, (int) inbytes
, US
"recv", NULL
);
2313 state
->xfer_error
= 1;
2316 #ifndef DISABLE_DKIM
2317 dkim_exim_verify_feed(state
->xfer_buffer
, inbytes
);
2319 state
->xfer_buffer_hwm
= (int) inbytes
;
2320 state
->xfer_buffer_lwm
= 0;
2324 /*************************************************
2325 * TLS version of getc *
2326 *************************************************/
2328 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2329 it refills the buffer via the GnuTLS reading function.
2330 Only used by the server-side TLS.
2332 This feeds DKIM and should be used for all message-body reads.
2334 Arguments: lim Maximum amount to read/bufffer
2335 Returns: the next character or EOF
2339 tls_getc(unsigned lim
)
2341 exim_gnutls_state_st
* state
= &state_server
;
2343 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
2344 if (!tls_refill(lim
))
2345 return state
->xfer_error
? EOF
: smtp_getc(lim
);
2347 /* Something in the buffer; return next uschar */
2349 return state
->xfer_buffer
[state
->xfer_buffer_lwm
++];
2353 tls_getbuf(unsigned * len
)
2355 exim_gnutls_state_st
* state
= &state_server
;
2359 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
2360 if (!tls_refill(*len
))
2362 if (!state
->xfer_error
) return smtp_getbuf(len
);
2367 if ((size
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
) > *len
)
2369 buf
= &state
->xfer_buffer
[state
->xfer_buffer_lwm
];
2370 state
->xfer_buffer_lwm
+= size
;
2379 #ifndef DISABLE_DKIM
2380 exim_gnutls_state_st
* state
= &state_server
;
2381 int n
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
;
2383 dkim_exim_verify_feed(state
->xfer_buffer
+state
->xfer_buffer_lwm
, n
);
2389 tls_could_read(void)
2391 return state_server
.xfer_buffer_lwm
< state_server
.xfer_buffer_hwm
2392 || gnutls_record_check_pending(state_server
.session
) > 0;
2398 /*************************************************
2399 * Read bytes from TLS channel *
2400 *************************************************/
2402 /* This does not feed DKIM, so if the caller uses this for reading message body,
2403 then the caller must feed DKIM.
2409 Returns: the number of bytes read
2410 -1 after a failed read
2414 tls_read(BOOL is_server
, uschar
*buff
, size_t len
)
2416 exim_gnutls_state_st
*state
= is_server
? &state_server
: &state_client
;
2422 if (state
->xfer_buffer_lwm
< state
->xfer_buffer_hwm
)
2424 debug_printf("*** PROBABLY A BUG *** " \
2425 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
2426 state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
);
2429 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT
")\n",
2430 state
->session
, buff
, len
);
2432 inbytes
= gnutls_record_recv(state
->session
, buff
, len
);
2433 if (inbytes
> 0) return inbytes
;
2436 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
2438 else record_io_error(state
, (int)inbytes
, US
"recv", NULL
);
2446 /*************************************************
2447 * Write bytes down TLS channel *
2448 *************************************************/
2452 is_server channel specifier
2455 more more data expected soon
2457 Returns: the number of bytes after a successful write,
2458 -1 after a failed write
2462 tls_write(BOOL is_server
, const uschar
*buff
, size_t len
, BOOL more
)
2466 exim_gnutls_state_st
*state
= is_server
? &state_server
: &state_client
;
2468 static BOOL corked
= FALSE
;
2470 if (more
&& !corked
) gnutls_record_cork(state
->session
);
2473 DEBUG(D_tls
) debug_printf("%s(%p, " SIZE_T_FMT
"%s)\n", __FUNCTION__
,
2474 buff
, left
, more
? ", more" : "");
2478 DEBUG(D_tls
) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT
")\n",
2480 outbytes
= gnutls_record_send(state
->session
, buff
, left
);
2482 DEBUG(D_tls
) debug_printf("outbytes=" SSIZE_T_FMT
"\n", outbytes
);
2485 record_io_error(state
, outbytes
, US
"send", NULL
);
2490 record_io_error(state
, 0, US
"send", US
"TLS channel closed on write");
2501 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT
") than INT_MAX\n",
2509 if (!more
) (void) gnutls_record_uncork(state
->session
, 0);
2520 /*************************************************
2521 * Random number generation *
2522 *************************************************/
2524 /* Pseudo-random number generation. The result is not expected to be
2525 cryptographically strong but not so weak that someone will shoot themselves
2526 in the foot using it as a nonce in input in some email header scheme or
2527 whatever weirdness they'll twist this into. The result should handle fork()
2528 and avoid repeating sequences. OpenSSL handles that for us.
2532 Returns a random number in range [0, max-1]
2535 #ifdef HAVE_GNUTLS_RND
2537 vaguely_random_number(int max
)
2542 uschar smallbuf
[sizeof(r
)];
2547 needed_len
= sizeof(r
);
2548 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2549 * asked for a number less than 10. */
2550 for (r
= max
, i
= 0; r
; ++i
)
2556 i
= gnutls_rnd(GNUTLS_RND_NONCE
, smallbuf
, needed_len
);
2559 DEBUG(D_all
) debug_printf("gnutls_rnd() failed, using fallback.\n");
2560 return vaguely_random_number_fallback(max
);
2563 for (p
= smallbuf
; needed_len
; --needed_len
, ++p
)
2569 /* We don't particularly care about weighted results; if someone wants
2570 * smooth distribution and cares enough then they should submit a patch then. */
2573 #else /* HAVE_GNUTLS_RND */
2575 vaguely_random_number(int max
)
2577 return vaguely_random_number_fallback(max
);
2579 #endif /* HAVE_GNUTLS_RND */
2584 /*************************************************
2585 * Let tls_require_ciphers be checked at startup *
2586 *************************************************/
2588 /* The tls_require_ciphers option, if set, must be something which the
2591 Returns: NULL on success, or error message
2595 tls_validate_require_cipher(void)
2598 uschar
*expciphers
= NULL
;
2599 gnutls_priority_t priority_cache
;
2601 uschar
* dummy_errstr
;
2603 #define validate_check_rc(Label) do { \
2604 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
2605 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
2606 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
2608 if (exim_gnutls_base_init_done
)
2609 log_write(0, LOG_MAIN
|LOG_PANIC
,
2610 "already initialised GnuTLS, Exim developer bug");
2612 #ifdef HAVE_GNUTLS_PKCS11
2613 if (!gnutls_allow_auto_pkcs11
)
2615 rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
);
2616 validate_check_rc(US
"gnutls_pkcs11_init");
2619 rc
= gnutls_global_init();
2620 validate_check_rc(US
"gnutls_global_init()");
2621 exim_gnutls_base_init_done
= TRUE
;
2623 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
2624 return_deinit(NULL
);
2626 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
2628 return_deinit(US
"failed to expand tls_require_ciphers");
2630 if (!(expciphers
&& *expciphers
))
2631 return_deinit(NULL
);
2634 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
2636 rc
= gnutls_priority_init(&priority_cache
, CS expciphers
, &errpos
);
2637 validate_check_rc(string_sprintf(
2638 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
2639 expciphers
, errpos
- CS expciphers
, errpos
));
2641 #undef return_deinit
2642 #undef validate_check_rc
2643 gnutls_global_deinit();
2651 /*************************************************
2652 * Report the library versions. *
2653 *************************************************/
2655 /* See a description in tls-openssl.c for an explanation of why this exists.
2657 Arguments: a FILE* to print the results to
2662 tls_version_report(FILE *f
)
2664 fprintf(f
, "Library version: GnuTLS: Compile: %s\n"
2667 gnutls_check_version(NULL
));
2672 /* End of tls-gnu.c */