1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Copyright (c) Phil Pennock 2012 */
10 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
11 one of the available supported implementations. This file is #included into
12 tls.c when USE_GNUTLS has been set.
14 The code herein is a revamp of GnuTLS integration using the current APIs; the
15 original tls-gnu.c was based on a patch which was contributed by Nikos
16 Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as
19 APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
20 which is not widely deployed by OS vendors. Will note issues below, which may
21 assist in updating the code in the future. Another sources of hints is
22 mod_gnutls for Apache (SNI callback registration and handling).
24 Keeping client and server variables more split than before and is currently
25 the norm, in anticipation of TLS in ACL callouts.
27 I wanted to switch to gnutls_certificate_set_verify_function() so that
28 certificate rejection could happen during handshake where it belongs, rather
29 than being dropped afterwards, but that was introduced in 2.10.0 and Debian
30 (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
32 (I wasn't looking for libraries quite that old, when updating to get rid of
33 compiler warnings of deprecated APIs. If it turns out that a lot of the rest
34 require current GnuTLS, then we'll drop support for the ancient libraries).
37 #include <gnutls/gnutls.h>
38 /* needed for cert checks in verification and DN extraction: */
39 #include <gnutls/x509.h>
40 /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
41 #include <gnutls/crypto.h>
43 /* needed to disable PKCS11 autoload unless requested */
44 #if GNUTLS_VERSION_NUMBER >= 0x020c00
45 # include <gnutls/pkcs11.h>
46 # define SUPPORT_PARAM_TO_PK_BITS
48 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
49 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
52 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
53 # warning "GnuTLS library version too old; tls:cert event unsupported"
54 # define DISABLE_EVENT
56 #if GNUTLS_VERSION_NUMBER >= 0x030306
57 # define SUPPORT_CA_DIR
59 # undef SUPPORT_CA_DIR
61 #if GNUTLS_VERSION_NUMBER >= 0x030014
62 # define SUPPORT_SYSDEFAULT_CABUNDLE
64 #if GNUTLS_VERSION_NUMBER >= 0x030104
65 # define GNUTLS_CERT_VFY_STATUS_PRINT
67 #if GNUTLS_VERSION_NUMBER >= 0x030109
70 #if GNUTLS_VERSION_NUMBER >= 0x03010a
71 # define SUPPORT_GNUTLS_SESS_DESC
73 #if GNUTLS_VERSION_NUMBER >= 0x030500
74 # define SUPPORT_GNUTLS_KEYLOG
76 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
77 # define SUPPORT_SRV_OCSP_STACK
81 # if GNUTLS_VERSION_NUMBER >= 0x030000
82 # define DANESSL_USAGE_DANE_TA 2
83 # define DANESSL_USAGE_DANE_EE 3
85 # error GnuTLS version too early for DANE
87 # if GNUTLS_VERSION_NUMBER < 0x999999
88 # define GNUTLS_BROKEN_DANE_VALIDATION
92 #ifdef EXPERIMENTAL_TLS_RESUME
93 # if GNUTLS_VERSION_NUMBER < 0x030603
94 # error GNUTLS version too early for session-resumption
99 # include <gnutls/ocsp.h>
102 # include <gnutls/dane.h>
105 #include "tls-cipher-stdname.c"
112 # ifdef EXPERIMENTAL_TLS_RESUME
113 builtin_macro_create_var(US
"_RESUME_DECODE", RESUME_DECODE_STRING
);
122 gnutls_global_set_audit_log_function()
125 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
128 /* Local static variables for GnuTLS */
130 /* Values for verify_requirement */
132 enum peer_verify_requirement
133 { VERIFY_NONE
, VERIFY_OPTIONAL
, VERIFY_REQUIRED
, VERIFY_DANE
};
135 /* This holds most state for server or client; with this, we can set up an
136 outbound TLS-enabled connection in an ACL callout, while not stomping all
137 over the TLS variables available for expansion.
139 Some of these correspond to variables in globals.c; those variables will
140 be set to point to content in one of these instances, as appropriate for
141 the stage of the process lifetime.
143 Not handled here: global tls_channelbinding_b64.
146 typedef struct exim_gnutls_state
{
147 gnutls_session_t session
;
148 gnutls_certificate_credentials_t x509_cred
;
149 gnutls_priority_t priority_cache
;
150 enum peer_verify_requirement verify_requirement
;
153 BOOL peer_cert_verified
;
154 BOOL peer_dane_verified
;
155 BOOL trigger_sni_changes
;
156 BOOL have_set_peerdn
;
157 const struct host_item
*host
; /* NULL if server */
158 gnutls_x509_crt_t peercert
;
161 uschar
*received_sni
;
163 const uschar
*tls_certificate
;
164 const uschar
*tls_privatekey
;
165 const uschar
*tls_sni
; /* client send only, not received */
166 const uschar
*tls_verify_certificates
;
167 const uschar
*tls_crl
;
168 const uschar
*tls_require_ciphers
;
170 uschar
*exp_tls_certificate
;
171 uschar
*exp_tls_privatekey
;
172 uschar
*exp_tls_verify_certificates
;
174 uschar
*exp_tls_require_ciphers
;
175 const uschar
*exp_tls_verify_cert_hostnames
;
176 #ifndef DISABLE_EVENT
177 uschar
*event_action
;
180 char * const * dane_data
;
181 const int * dane_data_len
;
184 tls_support
*tlsp
; /* set in tls_init() */
189 BOOL xfer_eof
; /*XXX never gets set! */
191 } exim_gnutls_state_st
;
193 static const exim_gnutls_state_st exim_gnutls_state_init
= {
194 /* all elements not explicitly intialised here get 0/NULL/FALSE */
199 /* Not only do we have our own APIs which don't pass around state, assuming
200 it's held in globals, GnuTLS doesn't appear to let us register callback data
201 for callbacks, or as part of the session, so we have to keep a "this is the
202 context we're currently dealing with" pointer and rely upon being
203 single-threaded to keep from processing data on an inbound TLS connection while
204 talking to another TLS connection for an outbound check. This does mean that
205 there's no way for heart-beats to be responded to, for the duration of the
207 XXX But see gnutls_session_get_ptr()
210 static exim_gnutls_state_st state_server
;
212 /* dh_params are initialised once within the lifetime of a process using TLS;
213 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
214 don't want to repeat this. */
216 static gnutls_dh_params_t dh_server_params
= NULL
;
218 static int ssl_session_timeout
= 7200; /* Two hours */
220 static const uschar
* const exim_default_gnutls_priority
= US
"NORMAL";
222 /* Guard library core initialisation */
224 static BOOL exim_gnutls_base_init_done
= FALSE
;
227 static BOOL gnutls_buggy_ocsp
= FALSE
;
230 #ifdef EXPERIMENTAL_TLS_RESUME
231 static gnutls_datum_t server_sessticket_key
;
234 /* ------------------------------------------------------------------------ */
237 #define MAX_HOST_LEN 255
239 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
240 the library logging; a value less than 0 disables the calls to set up logging
241 callbacks. GNuTLS also looks for an environment variable - except not for
242 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
243 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
244 but the env var must be added to /etc/sudoers too. */
245 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
246 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
249 #ifndef EXIM_CLIENT_DH_MIN_BITS
250 # define EXIM_CLIENT_DH_MIN_BITS 1024
253 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
254 can ask for a bit-strength. Without that, we stick to the constant we had
256 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
257 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
260 #define expand_check_tlsvar(Varname, errstr) \
261 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
263 #if GNUTLS_VERSION_NUMBER >= 0x020c00
264 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
265 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
266 # define HAVE_GNUTLS_RND
267 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
268 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
269 * isn't available sometimes, so this needs to become a conditional
270 * compilation; the sanest way to deal with this being a problem on
271 * older OSes is to block it in the Local/Makefile with this compiler
273 # ifndef AVOID_GNUTLS_PKCS11
274 # define HAVE_GNUTLS_PKCS11
275 # endif /* AVOID_GNUTLS_PKCS11 */
281 /* ------------------------------------------------------------------------ */
282 /* Callback declarations */
284 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
285 static void exim_gnutls_logger_cb(int level
, const char *message
);
288 static int exim_sni_handling_cb(gnutls_session_t session
);
291 static int server_ocsp_stapling_cb(gnutls_session_t session
, void * ptr
,
292 gnutls_datum_t
* ocsp_response
);
297 /* Daemon one-time initialisation */
299 tls_daemon_init(void)
301 #ifdef EXPERIMENTAL_TLS_RESUME
302 /* We are dependent on the GnuTLS implementation of the Session Ticket
303 encryption; both the strength and the key rotation period. We hope that
304 the strength at least matches that of the ciphersuite (but GnuTLS does not
307 static BOOL once
= FALSE
;
310 gnutls_session_ticket_key_generate(&server_sessticket_key
); /* >= 2.10.0 */
311 if (f
.running_in_test_harness
) ssl_session_timeout
= 6;
315 /* ------------------------------------------------------------------------ */
316 /* Static functions */
318 /*************************************************
320 *************************************************/
322 /* Called from lots of places when errors occur before actually starting to do
323 the TLS handshake, that is, while the session is still in clear. Always returns
324 DEFER for a server and FAIL for a client so that most calls can use "return
325 tls_error(...)" to do this processing and then give an appropriate return. A
326 single function is used for both server and client, because it is called from
327 some shared functions.
330 prefix text to include in the logged error
331 msg additional error string (may be NULL)
332 usually obtained from gnutls_strerror()
333 host NULL if setting up a server;
334 the connected host if setting up a client
335 errstr pointer to returned error string
337 Returns: OK/DEFER/FAIL
341 tls_error(const uschar
*prefix
, const uschar
*msg
, const host_item
*host
,
345 *errstr
= string_sprintf("(%s)%s%s", prefix
, msg
? ": " : "", msg
? msg
: US
"");
346 return host
? FAIL
: DEFER
;
351 tls_error_gnu(const uschar
*prefix
, int err
, const host_item
*host
,
354 return tls_error(prefix
, US
gnutls_strerror(err
), host
, errstr
);
358 tls_error_sys(const uschar
*prefix
, int err
, const host_item
*host
,
361 return tls_error(prefix
, US
strerror(err
), host
, errstr
);
365 /*************************************************
366 * Deal with logging errors during I/O *
367 *************************************************/
369 /* We have to get the identity of the peer from saved data.
372 state the current GnuTLS exim state container
373 rc the GnuTLS error code, or 0 if it's a local error
374 when text identifying read or write
375 text local error text when rc is 0
381 record_io_error(exim_gnutls_state_st
*state
, int rc
, uschar
*when
, uschar
*text
)
386 if (rc
== GNUTLS_E_FATAL_ALERT_RECEIVED
)
387 msg
= string_sprintf("A TLS fatal alert has been received: %s",
388 US
gnutls_alert_get_name(gnutls_alert_get(state
->session
)));
390 msg
= US
gnutls_strerror(rc
);
392 (void) tls_error(when
, msg
, state
->host
, &errstr
);
395 log_write(0, LOG_MAIN
, "H=%s [%s] TLS error on connection %s",
396 state
->host
->name
, state
->host
->address
, errstr
);
399 uschar
* conn_info
= smtp_get_connection_info();
400 if (Ustrncmp(conn_info
, US
"SMTP ", 5) == 0) conn_info
+= 5;
401 /* I'd like to get separated H= here, but too hard for now */
402 log_write(0, LOG_MAIN
, "TLS error on %s %s", conn_info
, errstr
);
409 /*************************************************
410 * Set various Exim expansion vars *
411 *************************************************/
413 #define exim_gnutls_cert_err(Label) \
416 if (rc != GNUTLS_E_SUCCESS) \
418 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
419 (Label), gnutls_strerror(rc)); \
425 import_cert(const gnutls_datum_t
* cert
, gnutls_x509_crt_t
* crtp
)
429 rc
= gnutls_x509_crt_init(crtp
);
430 exim_gnutls_cert_err(US
"gnutls_x509_crt_init (crt)");
432 rc
= gnutls_x509_crt_import(*crtp
, cert
, GNUTLS_X509_FMT_DER
);
433 exim_gnutls_cert_err(US
"failed to import certificate [gnutls_x509_crt_import(cert)]");
438 #undef exim_gnutls_cert_err
441 /* We set various Exim global variables from the state, once a session has
442 been established. With TLS callouts, may need to change this to stack
443 variables, or just re-call it with the server state after client callout
446 Make sure anything set here is unset in tls_getc().
450 tls_bits strength indicator
451 tls_certificate_verified bool indicator
452 tls_channelbinding_b64 for some SASL mechanisms
454 tls_peercert pointer to library internal
456 tls_sni a (UTF-8) string
457 tls_ourcert pointer to library internal
460 state the relevant exim_gnutls_state_st *
464 extract_exim_vars_from_tls_state(exim_gnutls_state_st
* state
)
466 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
469 gnutls_datum_t channel
;
471 tls_support
* tlsp
= state
->tlsp
;
473 tlsp
->active
.sock
= state
->fd_out
;
474 tlsp
->active
.tls_ctx
= state
;
476 DEBUG(D_tls
) debug_printf("cipher: %s\n", state
->ciphersuite
);
478 tlsp
->certificate_verified
= state
->peer_cert_verified
;
480 tlsp
->dane_verified
= state
->peer_dane_verified
;
483 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
484 only available for use for authenticators while this TLS session is running. */
486 tls_channelbinding_b64
= NULL
;
487 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
490 if ((rc
= gnutls_session_channel_binding(state
->session
, GNUTLS_CB_TLS_UNIQUE
, &channel
)))
491 { DEBUG(D_tls
) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc
)); }
494 old_pool
= store_pool
;
495 store_pool
= POOL_PERM
;
496 tls_channelbinding_b64
= b64encode(CUS channel
.data
, (int)channel
.size
);
497 store_pool
= old_pool
;
498 DEBUG(D_tls
) debug_printf("Have channel bindings cached for possible auth usage.\n");
502 /* peercert is set in peer_status() */
503 tlsp
->peerdn
= state
->peerdn
;
504 tlsp
->sni
= state
->received_sni
;
506 /* record our certificate */
508 const gnutls_datum_t
* cert
= gnutls_certificate_get_ours(state
->session
);
509 gnutls_x509_crt_t crt
;
511 tlsp
->ourcert
= cert
&& import_cert(cert
, &crt
)==0 ? crt
: NULL
;
518 /*************************************************
519 * Setup up DH parameters *
520 *************************************************/
522 /* Generating the D-H parameters may take a long time. They only need to
523 be re-generated every so often, depending on security policy. What we do is to
524 keep these parameters in a file in the spool directory. If the file does not
525 exist, we generate them. This means that it is easy to cause a regeneration.
527 The new file is written as a temporary file and renamed, so that an incomplete
528 file is never present. If two processes both compute some new parameters, you
529 waste a bit of effort, but it doesn't seem worth messing around with locking to
532 Returns: OK/DEFER/FAIL
536 init_server_dh(uschar
** errstr
)
539 unsigned int dh_bits
;
541 uschar filename_buf
[PATH_MAX
];
542 uschar
*filename
= NULL
;
544 uschar
*exp_tls_dhparam
;
545 BOOL use_file_in_spool
= FALSE
;
546 host_item
*host
= NULL
; /* dummy for macros */
548 DEBUG(D_tls
) debug_printf("Initialising GnuTLS server params.\n");
550 if ((rc
= gnutls_dh_params_init(&dh_server_params
)))
551 return tls_error_gnu(US
"gnutls_dh_params_init", rc
, host
, errstr
);
556 if (!expand_check(tls_dhparam
, US
"tls_dhparam", &exp_tls_dhparam
, errstr
))
559 if (!exp_tls_dhparam
)
561 DEBUG(D_tls
) debug_printf("Loading default hard-coded DH params\n");
562 m
.data
= US
std_dh_prime_default();
563 m
.size
= Ustrlen(m
.data
);
565 else if (Ustrcmp(exp_tls_dhparam
, "historic") == 0)
566 use_file_in_spool
= TRUE
;
567 else if (Ustrcmp(exp_tls_dhparam
, "none") == 0)
569 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
572 else if (exp_tls_dhparam
[0] != '/')
574 if (!(m
.data
= US
std_dh_prime_named(exp_tls_dhparam
)))
575 return tls_error(US
"No standard prime named", exp_tls_dhparam
, NULL
, errstr
);
576 m
.size
= Ustrlen(m
.data
);
579 filename
= exp_tls_dhparam
;
583 if ((rc
= gnutls_dh_params_import_pkcs3(dh_server_params
, &m
, GNUTLS_X509_FMT_PEM
)))
584 return tls_error_gnu(US
"gnutls_dh_params_import_pkcs3", rc
, host
, errstr
);
585 DEBUG(D_tls
) debug_printf("Loaded fixed standard D-H parameters\n");
589 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
590 /* If you change this constant, also change dh_param_fn_ext so that we can use a
591 different filename and ensure we have sufficient bits. */
593 if (!(dh_bits
= gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH
, GNUTLS_SEC_PARAM_NORMAL
)))
594 return tls_error(US
"gnutls_sec_param_to_pk_bits() failed", NULL
, NULL
, errstr
);
596 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
599 dh_bits
= EXIM_SERVER_DH_BITS_PRE2_12
;
601 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
605 /* Some clients have hard-coded limits. */
606 if (dh_bits
> tls_dh_max_bits
)
609 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
611 dh_bits
= tls_dh_max_bits
;
614 if (use_file_in_spool
)
616 if (!string_format(filename_buf
, sizeof(filename_buf
),
617 "%s/gnutls-params-%d", spool_directory
, dh_bits
))
618 return tls_error(US
"overlong filename", NULL
, NULL
, errstr
);
619 filename
= filename_buf
;
622 /* Open the cache file for reading and if successful, read it and set up the
625 if ((fd
= Uopen(filename
, O_RDONLY
, 0)) >= 0)
631 if (fstat(fd
, &statbuf
) < 0) /* EIO */
635 return tls_error_sys(US
"TLS cache stat failed", saved_errno
, NULL
, errstr
);
637 if (!S_ISREG(statbuf
.st_mode
))
640 return tls_error(US
"TLS cache not a file", NULL
, NULL
, errstr
);
642 if (!(fp
= fdopen(fd
, "rb")))
646 return tls_error_sys(US
"fdopen(TLS cache stat fd) failed",
647 saved_errno
, NULL
, errstr
);
650 m
.size
= statbuf
.st_size
;
651 if (!(m
.data
= store_malloc(m
.size
)))
654 return tls_error_sys(US
"malloc failed", errno
, NULL
, errstr
);
656 if (!(sz
= fread(m
.data
, m
.size
, 1, fp
)))
661 return tls_error_sys(US
"fread failed", saved_errno
, NULL
, errstr
);
665 rc
= gnutls_dh_params_import_pkcs3(dh_server_params
, &m
, GNUTLS_X509_FMT_PEM
);
668 return tls_error_gnu(US
"gnutls_dh_params_import_pkcs3", rc
, host
, errstr
);
669 DEBUG(D_tls
) debug_printf("read D-H parameters from file \"%s\"\n", filename
);
672 /* If the file does not exist, fall through to compute new data and cache it.
673 If there was any other opening error, it is serious. */
675 else if (errno
== ENOENT
)
679 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename
);
682 return tls_error(string_open_failed(errno
, "\"%s\" for reading", filename
),
685 /* If ret < 0, either the cache file does not exist, or the data it contains
686 is not useful. One particular case of this is when upgrading from an older
687 release of Exim in which the data was stored in a different format. We don't
688 try to be clever and support both formats; we just regenerate new data in this
694 unsigned int dh_bits_gen
= dh_bits
;
696 if ((PATH_MAX
- Ustrlen(filename
)) < 10)
697 return tls_error(US
"Filename too long to generate replacement",
698 filename
, NULL
, errstr
);
700 temp_fn
= string_copy(US
"%s.XXXXXXX");
701 if ((fd
= mkstemp(CS temp_fn
)) < 0) /* modifies temp_fn */
702 return tls_error_sys(US
"Unable to open temp file", errno
, NULL
, errstr
);
703 (void)exim_chown(temp_fn
, exim_uid
, exim_gid
); /* Probably not necessary */
705 /* GnuTLS overshoots!
706 * If we ask for 2236, we might get 2237 or more.
707 * But there's no way to ask GnuTLS how many bits there really are.
708 * We can ask how many bits were used in a TLS session, but that's it!
709 * The prime itself is hidden behind too much abstraction.
710 * So we ask for less, and proceed on a wing and a prayer.
711 * First attempt, subtracted 3 for 2233 and got 2240.
713 if (dh_bits
>= EXIM_CLIENT_DH_MIN_BITS
+ 10)
715 dh_bits_gen
= dh_bits
- 10;
717 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
722 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
724 if ((rc
= gnutls_dh_params_generate2(dh_server_params
, dh_bits_gen
)))
725 return tls_error_gnu(US
"gnutls_dh_params_generate2", rc
, host
, errstr
);
727 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
728 and I confirmed that a NULL call to get the size first is how the GnuTLS
729 sample apps handle this. */
733 if ( (rc
= gnutls_dh_params_export_pkcs3(dh_server_params
,
734 GNUTLS_X509_FMT_PEM
, m
.data
, &sz
))
735 && rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
736 return tls_error_gnu(US
"gnutls_dh_params_export_pkcs3(NULL) sizing",
739 if (!(m
.data
= store_malloc(m
.size
)))
740 return tls_error_sys(US
"memory allocation failed", errno
, NULL
, errstr
);
742 /* this will return a size 1 less than the allocation size above */
743 if ((rc
= gnutls_dh_params_export_pkcs3(dh_server_params
, GNUTLS_X509_FMT_PEM
,
747 return tls_error_gnu(US
"gnutls_dh_params_export_pkcs3() real", rc
, host
, errstr
);
749 m
.size
= sz
; /* shrink by 1, probably */
751 if ((sz
= write_to_fd_buf(fd
, m
.data
, (size_t) m
.size
)) != m
.size
)
754 return tls_error_sys(US
"TLS cache write D-H params failed",
755 errno
, NULL
, errstr
);
758 if ((sz
= write_to_fd_buf(fd
, US
"\n", 1)) != 1)
759 return tls_error_sys(US
"TLS cache write D-H params final newline failed",
760 errno
, NULL
, errstr
);
762 if ((rc
= close(fd
)))
763 return tls_error_sys(US
"TLS cache write close() failed", errno
, NULL
, errstr
);
765 if (Urename(temp_fn
, filename
) < 0)
766 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
767 temp_fn
, filename
), errno
, NULL
, errstr
);
769 DEBUG(D_tls
) debug_printf("wrote D-H parameters to file \"%s\"\n", filename
);
772 DEBUG(D_tls
) debug_printf("initialized server D-H parameters\n");
779 /* Create and install a selfsigned certificate, for use in server mode */
782 tls_install_selfsign(exim_gnutls_state_st
* state
, uschar
** errstr
)
784 gnutls_x509_crt_t cert
= NULL
;
786 gnutls_x509_privkey_t pkey
= NULL
;
787 const uschar
* where
;
790 where
= US
"initialising pkey";
791 if ((rc
= gnutls_x509_privkey_init(&pkey
))) goto err
;
793 where
= US
"initialising cert";
794 if ((rc
= gnutls_x509_crt_init(&cert
))) goto err
;
796 where
= US
"generating pkey";
797 if ((rc
= gnutls_x509_privkey_generate(pkey
, GNUTLS_PK_RSA
,
798 #ifdef SUPPORT_PARAM_TO_PK_BITS
799 # ifndef GNUTLS_SEC_PARAM_MEDIUM
800 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
802 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA
, GNUTLS_SEC_PARAM_MEDIUM
),
809 where
= US
"configuring cert";
811 if ( (rc
= gnutls_x509_crt_set_version(cert
, 3))
812 || (rc
= gnutls_x509_crt_set_serial(cert
, &now
, sizeof(now
)))
813 || (rc
= gnutls_x509_crt_set_activation_time(cert
, now
= time(NULL
)))
814 || (rc
= gnutls_x509_crt_set_expiration_time(cert
, now
+ 60 * 60)) /* 1 hr */
815 || (rc
= gnutls_x509_crt_set_key(cert
, pkey
))
817 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
818 GNUTLS_OID_X520_COUNTRY_NAME
, 0, "UK", 2))
819 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
820 GNUTLS_OID_X520_ORGANIZATION_NAME
, 0, "Exim Developers", 15))
821 || (rc
= gnutls_x509_crt_set_dn_by_oid(cert
,
822 GNUTLS_OID_X520_COMMON_NAME
, 0,
823 smtp_active_hostname
, Ustrlen(smtp_active_hostname
)))
827 where
= US
"signing cert";
828 if ((rc
= gnutls_x509_crt_sign(cert
, cert
, pkey
))) goto err
;
830 where
= US
"installing selfsign cert";
832 if ((rc
= gnutls_certificate_set_x509_key(state
->x509_cred
, &cert
, 1, pkey
)))
838 if (cert
) gnutls_x509_crt_deinit(cert
);
839 if (pkey
) gnutls_x509_privkey_deinit(pkey
);
843 rc
= tls_error_gnu(where
, rc
, NULL
, errstr
);
850 /* Add certificate and key, from files.
853 Zero or negative: good. Negate value for certificate index if < 0.
854 Greater than zero: FAIL or DEFER code.
858 tls_add_certfile(exim_gnutls_state_st
* state
, const host_item
* host
,
859 uschar
* certfile
, uschar
* keyfile
, uschar
** errstr
)
861 int rc
= gnutls_certificate_set_x509_key_file(state
->x509_cred
,
862 CS certfile
, CS keyfile
, GNUTLS_X509_FMT_PEM
);
864 return tls_error_gnu(
865 string_sprintf("cert/key setup: cert=%s key=%s", certfile
, keyfile
),
871 /*************************************************
872 * Variables re-expanded post-SNI *
873 *************************************************/
875 /* Called from both server and client code, via tls_init(), and also from
876 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
878 We can tell the two apart by state->received_sni being non-NULL in callback.
880 The callback should not call us unless state->trigger_sni_changes is true,
881 which we are responsible for setting on the first pass through.
884 state exim_gnutls_state_st *
885 errstr error string pointer
887 Returns: OK/DEFER/FAIL
891 tls_expand_session_files(exim_gnutls_state_st
* state
, uschar
** errstr
)
895 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
896 uschar
*saved_tls_certificate
= NULL
;
897 uschar
*saved_tls_privatekey
= NULL
;
898 uschar
*saved_tls_verify_certificates
= NULL
;
899 uschar
*saved_tls_crl
= NULL
;
902 /* We check for tls_sni *before* expansion. */
903 if (!host
) /* server */
904 if (!state
->received_sni
)
906 if ( state
->tls_certificate
907 && ( Ustrstr(state
->tls_certificate
, US
"tls_sni")
908 || Ustrstr(state
->tls_certificate
, US
"tls_in_sni")
909 || Ustrstr(state
->tls_certificate
, US
"tls_out_sni")
912 DEBUG(D_tls
) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
913 state
->trigger_sni_changes
= TRUE
;
918 /* useful for debugging */
919 saved_tls_certificate
= state
->exp_tls_certificate
;
920 saved_tls_privatekey
= state
->exp_tls_privatekey
;
921 saved_tls_verify_certificates
= state
->exp_tls_verify_certificates
;
922 saved_tls_crl
= state
->exp_tls_crl
;
925 if ((rc
= gnutls_certificate_allocate_credentials(&state
->x509_cred
)))
926 return tls_error_gnu(US
"gnutls_certificate_allocate_credentials",
929 #ifdef SUPPORT_SRV_OCSP_STACK
930 gnutls_certificate_set_flags(state
->x509_cred
, GNUTLS_CERTIFICATE_API_V2
);
933 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
934 state members, assuming consistent naming; and expand_check() returns
935 false if expansion failed, unless expansion was forced to fail. */
937 /* check if we at least have a certificate, before doing expensive
940 if (!expand_check_tlsvar(tls_certificate
, errstr
))
943 /* certificate is mandatory in server, optional in client */
945 if ( !state
->exp_tls_certificate
946 || !*state
->exp_tls_certificate
949 return tls_install_selfsign(state
, errstr
);
951 DEBUG(D_tls
) debug_printf("TLS: no client certificate specified; okay\n");
953 if (state
->tls_privatekey
&& !expand_check_tlsvar(tls_privatekey
, errstr
))
956 /* tls_privatekey is optional, defaulting to same file as certificate */
958 if (state
->tls_privatekey
== NULL
|| *state
->tls_privatekey
== '\0')
960 state
->tls_privatekey
= state
->tls_certificate
;
961 state
->exp_tls_privatekey
= state
->exp_tls_certificate
;
965 if (state
->exp_tls_certificate
&& *state
->exp_tls_certificate
)
967 DEBUG(D_tls
) debug_printf("certificate file = %s\nkey file = %s\n",
968 state
->exp_tls_certificate
, state
->exp_tls_privatekey
);
970 if (state
->received_sni
)
971 if ( Ustrcmp(state
->exp_tls_certificate
, saved_tls_certificate
) == 0
972 && Ustrcmp(state
->exp_tls_privatekey
, saved_tls_privatekey
) == 0
975 DEBUG(D_tls
) debug_printf("TLS SNI: cert and key unchanged\n");
979 DEBUG(D_tls
) debug_printf("TLS SNI: have a changed cert/key pair.\n");
982 if (!host
) /* server */
984 const uschar
* clist
= state
->exp_tls_certificate
;
985 const uschar
* klist
= state
->exp_tls_privatekey
;
986 const uschar
* olist
;
987 int csep
= 0, ksep
= 0, osep
= 0, cnt
= 0;
988 uschar
* cfile
, * kfile
, * ofile
;
991 if (!expand_check(tls_ocsp_file
, US
"tls_ocsp_file", &ofile
, errstr
))
996 while (cfile
= string_nextinlist(&clist
, &csep
, NULL
, 0))
998 if (!(kfile
= string_nextinlist(&klist
, &ksep
, NULL
, 0)))
999 return tls_error(US
"cert/key setup: out of keys", NULL
, host
, errstr
);
1000 else if (0 < (rc
= tls_add_certfile(state
, host
, cfile
, kfile
, errstr
)))
1004 int gnutls_cert_index
= -rc
;
1005 DEBUG(D_tls
) debug_printf("TLS: cert/key %s registered\n", cfile
);
1007 /* Set the OCSP stapling server info */
1009 #ifndef DISABLE_OCSP
1011 if (gnutls_buggy_ocsp
)
1014 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1016 else if ((ofile
= string_nextinlist(&olist
, &osep
, NULL
, 0)))
1018 /* Use the full callback method for stapling just to get
1019 observability. More efficient would be to read the file once only,
1020 if it never changed (due to SNI). Would need restart on file update,
1021 or watch datestamp. */
1023 # ifdef SUPPORT_SRV_OCSP_STACK
1024 if ((rc
= gnutls_certificate_set_ocsp_status_request_function2(
1025 state
->x509_cred
, gnutls_cert_index
,
1026 server_ocsp_stapling_cb
, ofile
)))
1027 return tls_error_gnu(
1028 US
"gnutls_certificate_set_ocsp_status_request_function2",
1034 debug_printf("oops; multiple OCSP files not supported\n");
1037 gnutls_certificate_set_ocsp_status_request_function(
1038 state
->x509_cred
, server_ocsp_stapling_cb
, ofile
);
1041 DEBUG(D_tls
) debug_printf("OCSP response file = %s\n", ofile
);
1044 DEBUG(D_tls
) debug_printf("ran out of OCSP response files in list\n");
1050 if (0 < (rc
= tls_add_certfile(state
, host
,
1051 state
->exp_tls_certificate
, state
->exp_tls_privatekey
, errstr
)))
1053 DEBUG(D_tls
) debug_printf("TLS: cert/key registered\n");
1056 } /* tls_certificate */
1059 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1060 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1061 error message is provided. However, if we just refrain from setting anything up
1062 in that case, certificate verification fails, which seems to be the correct
1065 if (state
->tls_verify_certificates
&& *state
->tls_verify_certificates
)
1067 if (!expand_check_tlsvar(tls_verify_certificates
, errstr
))
1069 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1070 if (Ustrcmp(state
->exp_tls_verify_certificates
, "system") == 0)
1071 state
->exp_tls_verify_certificates
= NULL
;
1073 if (state
->tls_crl
&& *state
->tls_crl
)
1074 if (!expand_check_tlsvar(tls_crl
, errstr
))
1077 if (!(state
->exp_tls_verify_certificates
&&
1078 *state
->exp_tls_verify_certificates
))
1081 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1082 /* With no tls_verify_certificates, we ignore tls_crl too */
1089 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1093 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1094 if (Ustrcmp(state
->exp_tls_verify_certificates
, "system") == 0)
1095 cert_count
= gnutls_certificate_set_x509_system_trust(state
->x509_cred
);
1099 if (Ustat(state
->exp_tls_verify_certificates
, &statbuf
) < 0)
1101 log_write(0, LOG_MAIN
|LOG_PANIC
, "could not stat %s "
1102 "(tls_verify_certificates): %s", state
->exp_tls_verify_certificates
,
1107 #ifndef SUPPORT_CA_DIR
1108 /* The test suite passes in /dev/null; we could check for that path explicitly,
1109 but who knows if someone has some weird FIFO which always dumps some certs, or
1110 other weirdness. The thing we really want to check is that it's not a
1111 directory, since while OpenSSL supports that, GnuTLS does not.
1112 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1113 if (S_ISDIR(statbuf
.st_mode
))
1116 debug_printf("verify certificates path is a dir: \"%s\"\n",
1117 state
->exp_tls_verify_certificates
);
1118 log_write(0, LOG_MAIN
|LOG_PANIC
,
1119 "tls_verify_certificates \"%s\" is a directory",
1120 state
->exp_tls_verify_certificates
);
1125 DEBUG(D_tls
) debug_printf("verify certificates = %s size=" OFF_T_FMT
"\n",
1126 state
->exp_tls_verify_certificates
, statbuf
.st_size
);
1128 if (statbuf
.st_size
== 0)
1131 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1137 #ifdef SUPPORT_CA_DIR
1138 (statbuf
.st_mode
& S_IFMT
) == S_IFDIR
1140 gnutls_certificate_set_x509_trust_dir(state
->x509_cred
,
1141 CS state
->exp_tls_verify_certificates
, GNUTLS_X509_FMT_PEM
)
1144 gnutls_certificate_set_x509_trust_file(state
->x509_cred
,
1145 CS state
->exp_tls_verify_certificates
, GNUTLS_X509_FMT_PEM
);
1147 #ifdef SUPPORT_CA_DIR
1148 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1149 when using the directory-of-certs config model. */
1151 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
1152 gnutls_certificate_send_x509_rdn_sequence(state
->session
, 1);
1157 return tls_error_gnu(US
"setting certificate trust", cert_count
, host
, errstr
);
1159 debug_printf("Added %d certificate authorities.\n", cert_count
);
1161 if (state
->tls_crl
&& *state
->tls_crl
&&
1162 state
->exp_tls_crl
&& *state
->exp_tls_crl
)
1164 DEBUG(D_tls
) debug_printf("loading CRL file = %s\n", state
->exp_tls_crl
);
1165 if ((cert_count
= gnutls_certificate_set_x509_crl_file(state
->x509_cred
,
1166 CS state
->exp_tls_crl
, GNUTLS_X509_FMT_PEM
)) < 0)
1167 return tls_error_gnu(US
"gnutls_certificate_set_x509_crl_file",
1168 cert_count
, host
, errstr
);
1170 DEBUG(D_tls
) debug_printf("Processed %d CRLs.\n", cert_count
);
1179 /*************************************************
1180 * Set X.509 state variables *
1181 *************************************************/
1183 /* In GnuTLS, the registered cert/key are not replaced by a later
1184 set of a cert/key, so for SNI support we need a whole new x509_cred
1185 structure. Which means various other non-re-expanded pieces of state
1186 need to be re-set in the new struct, so the setting logic is pulled
1190 state exim_gnutls_state_st *
1191 errstr error string pointer
1193 Returns: OK/DEFER/FAIL
1197 tls_set_remaining_x509(exim_gnutls_state_st
*state
, uschar
** errstr
)
1200 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
1202 /* Create D-H parameters, or read them from the cache file. This function does
1203 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1204 client-side params. */
1208 if (!dh_server_params
)
1209 if ((rc
= init_server_dh(errstr
)) != OK
) return rc
;
1210 gnutls_certificate_set_dh_params(state
->x509_cred
, dh_server_params
);
1213 /* Link the credentials to the session. */
1215 if ((rc
= gnutls_credentials_set(state
->session
,
1216 GNUTLS_CRD_CERTIFICATE
, state
->x509_cred
)))
1217 return tls_error_gnu(US
"gnutls_credentials_set", rc
, host
, errstr
);
1222 /*************************************************
1223 * Initialize for GnuTLS *
1224 *************************************************/
1227 #ifndef DISABLE_OCSP
1230 tls_is_buggy_ocsp(void)
1233 uschar maj
, mid
, mic
;
1235 s
= CUS
gnutls_check_version(NULL
);
1239 while (*s
&& *s
!= '.') s
++;
1240 mid
= atoi(CCS
++s
);
1247 while (*s
&& *s
!= '.') s
++;
1248 mic
= atoi(CCS
++s
);
1249 return mic
<= (mid
== 3 ? 16 : 3);
1258 /* Called from both server and client code. In the case of a server, errors
1259 before actual TLS negotiation return DEFER.
1262 host connected host, if client; NULL if server
1263 certificate certificate file
1264 privatekey private key file
1265 sni TLS SNI to send, sometimes when client; else NULL
1268 require_ciphers tls_require_ciphers setting
1269 caller_state returned state-info structure
1270 errstr error string pointer
1272 Returns: OK/DEFER/FAIL
1277 const host_item
*host
,
1278 const uschar
*certificate
,
1279 const uschar
*privatekey
,
1283 const uschar
*require_ciphers
,
1284 exim_gnutls_state_st
**caller_state
,
1288 exim_gnutls_state_st
* state
;
1291 const char * errpos
;
1294 if (!exim_gnutls_base_init_done
)
1296 DEBUG(D_tls
) debug_printf("GnuTLS global init required.\n");
1298 #ifdef HAVE_GNUTLS_PKCS11
1299 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1300 which loads modules from a config file, which sounds good and may be wanted
1301 by some sysadmin, but also means in common configurations that GNOME keyring
1302 environment variables are used and so breaks for users calling mailq.
1303 To prevent this, we init PKCS11 first, which is the documented approach. */
1304 if (!gnutls_allow_auto_pkcs11
)
1305 if ((rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
)))
1306 return tls_error_gnu(US
"gnutls_pkcs11_init", rc
, host
, errstr
);
1309 if ((rc
= gnutls_global_init()))
1310 return tls_error_gnu(US
"gnutls_global_init", rc
, host
, errstr
);
1312 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1315 gnutls_global_set_log_function(exim_gnutls_logger_cb
);
1316 /* arbitrarily chosen level; bump up to 9 for more */
1317 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL
);
1321 #ifndef DISABLE_OCSP
1322 if (tls_ocsp_file
&& (gnutls_buggy_ocsp
= tls_is_buggy_ocsp()))
1323 log_write(0, LOG_MAIN
, "OCSP unusable with this GnuTLS library version");
1326 exim_gnutls_base_init_done
= TRUE
;
1331 /* For client-side sessions we allocate a context. This lets us run
1332 several in parallel. */
1333 int old_pool
= store_pool
;
1334 store_pool
= POOL_PERM
;
1335 state
= store_get(sizeof(exim_gnutls_state_st
), FALSE
);
1336 store_pool
= old_pool
;
1338 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1340 DEBUG(D_tls
) debug_printf("initialising GnuTLS client session\n");
1341 rc
= gnutls_init(&state
->session
, GNUTLS_CLIENT
);
1345 state
= &state_server
;
1346 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1348 DEBUG(D_tls
) debug_printf("initialising GnuTLS server session\n");
1349 rc
= gnutls_init(&state
->session
, GNUTLS_SERVER
);
1352 return tls_error_gnu(US
"gnutls_init", rc
, host
, errstr
);
1356 state
->tls_certificate
= certificate
;
1357 state
->tls_privatekey
= privatekey
;
1358 state
->tls_require_ciphers
= require_ciphers
;
1359 state
->tls_sni
= sni
;
1360 state
->tls_verify_certificates
= cas
;
1361 state
->tls_crl
= crl
;
1363 /* This handles the variables that might get re-expanded after TLS SNI;
1364 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1367 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1368 if ((rc
= tls_expand_session_files(state
, errstr
)) != OK
) return rc
;
1370 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1371 requires a new structure afterwards. */
1373 if ((rc
= tls_set_remaining_x509(state
, errstr
)) != OK
) return rc
;
1375 /* set SNI in client, only */
1378 if (!expand_check(sni
, US
"tls_out_sni", &state
->tlsp
->sni
, errstr
))
1380 if (state
->tlsp
->sni
&& *state
->tlsp
->sni
)
1383 debug_printf("Setting TLS client SNI to \"%s\"\n", state
->tlsp
->sni
);
1384 sz
= Ustrlen(state
->tlsp
->sni
);
1385 if ((rc
= gnutls_server_name_set(state
->session
,
1386 GNUTLS_NAME_DNS
, state
->tlsp
->sni
, sz
)))
1387 return tls_error_gnu(US
"gnutls_server_name_set", rc
, host
, errstr
);
1390 else if (state
->tls_sni
)
1391 DEBUG(D_tls
) debug_printf("*** PROBABLY A BUG *** " \
1392 "have an SNI set for a server [%s]\n", state
->tls_sni
);
1394 /* This is the priority string support,
1395 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1396 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1397 This was backwards incompatible, but means Exim no longer needs to track
1398 all algorithms and provide string forms for them. */
1401 if (state
->tls_require_ciphers
&& *state
->tls_require_ciphers
)
1403 if (!expand_check_tlsvar(tls_require_ciphers
, errstr
))
1405 if (state
->exp_tls_require_ciphers
&& *state
->exp_tls_require_ciphers
)
1407 p
= state
->exp_tls_require_ciphers
;
1408 DEBUG(D_tls
) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p
);
1413 p
= exim_default_gnutls_priority
;
1415 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p
);
1418 if ((rc
= gnutls_priority_init(&state
->priority_cache
, CCS p
, &errpos
)))
1419 return tls_error_gnu(string_sprintf(
1420 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1421 p
, errpos
- CS p
, errpos
),
1424 if ((rc
= gnutls_priority_set(state
->session
, state
->priority_cache
)))
1425 return tls_error_gnu(US
"gnutls_priority_set", rc
, host
, errstr
);
1427 /* This also sets the server ticket expiration time to the same, and
1428 the STEK rotation time to 3x. */
1430 gnutls_db_set_cache_expiration(state
->session
, ssl_session_timeout
);
1432 /* Reduce security in favour of increased compatibility, if the admin
1433 decides to make that trade-off. */
1434 if (gnutls_compat_mode
)
1436 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1437 DEBUG(D_tls
) debug_printf("lowering GnuTLS security, compatibility mode\n");
1438 gnutls_session_enable_compatibility_mode(state
->session
);
1440 DEBUG(D_tls
) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1444 *caller_state
= state
;
1450 /*************************************************
1451 * Extract peer information *
1452 *************************************************/
1454 static const uschar
*
1455 cipher_stdname_kcm(gnutls_kx_algorithm_t kx
, gnutls_cipher_algorithm_t cipher
,
1456 gnutls_mac_algorithm_t mac
)
1459 gnutls_kx_algorithm_t kx_i
;
1460 gnutls_cipher_algorithm_t cipher_i
;
1461 gnutls_mac_algorithm_t mac_i
;
1464 gnutls_cipher_suite_info(i
, cs_id
, &kx_i
, &cipher_i
, &mac_i
, NULL
);
1466 if (kx_i
== kx
&& cipher_i
== cipher
&& mac_i
== mac
)
1467 return cipher_stdname(cs_id
[0], cs_id
[1]);
1473 /* Called from both server and client code.
1474 Only this is allowed to set state->peerdn and state->have_set_peerdn
1475 and we use that to detect double-calls.
1477 NOTE: the state blocks last while the TLS connection is up, which is fine
1478 for logging in the server side, but for the client side, we log after teardown
1479 in src/deliver.c. While the session is up, we can twist about states and
1480 repoint tls_* globals, but those variables used for logging or other variable
1481 expansion that happens _after_ delivery need to have a longer life-time.
1483 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1484 doing this more than once per generation of a state context. We set them in
1485 the state context, and repoint tls_* to them. After the state goes away, the
1486 tls_* copies of the pointers remain valid and client delivery logging is happy.
1488 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1492 state exim_gnutls_state_st *
1493 errstr pointer to error string
1495 Returns: OK/DEFER/FAIL
1499 peer_status(exim_gnutls_state_st
* state
, uschar
** errstr
)
1501 gnutls_session_t session
= state
->session
;
1502 const gnutls_datum_t
* cert_list
;
1504 unsigned int cert_list_size
= 0;
1505 gnutls_protocol_t protocol
;
1506 gnutls_cipher_algorithm_t cipher
;
1507 gnutls_kx_algorithm_t kx
;
1508 gnutls_mac_algorithm_t mac
;
1509 gnutls_certificate_type_t ct
;
1510 gnutls_x509_crt_t crt
;
1514 if (state
->have_set_peerdn
)
1516 state
->have_set_peerdn
= TRUE
;
1518 state
->peerdn
= NULL
;
1521 cipher
= gnutls_cipher_get(session
);
1522 protocol
= gnutls_protocol_get_version(session
);
1523 mac
= gnutls_mac_get(session
);
1525 #ifdef GNUTLS_TLS1_3
1526 protocol
>= GNUTLS_TLS1_3
? 0 :
1528 gnutls_kx_get(session
);
1530 old_pool
= store_pool
;
1532 tls_support
* tlsp
= state
->tlsp
;
1533 store_pool
= POOL_PERM
;
1535 #ifdef SUPPORT_GNUTLS_SESS_DESC
1538 uschar
* s
= US
gnutls_session_get_desc(session
), c
;
1540 /* Nikos M suggests we use this by preference. It returns like:
1541 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
1543 For partial back-compat, put a colon after the TLS version, replace the
1544 )-( grouping with __, replace in-group - with _ and append the :keysize. */
1546 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
1548 for (s
++; (c
= *s
) && c
!= ')'; s
++) g
= string_catn(g
, s
, 1);
1549 g
= string_catn(g
, US
":", 1);
1550 if (*s
) s
++; /* now on _ between groups */
1553 for (*++s
&& ++s
; (c
= *s
) && c
!= ')'; s
++) g
= string_catn(g
, c
== '-' ? US
"_" : s
, 1);
1554 /* now on ) closing group */
1555 if ((c
= *s
) && *++s
== '-') g
= string_catn(g
, US
"__", 2);
1556 /* now on _ between groups */
1558 g
= string_catn(g
, US
":", 1);
1559 g
= string_cat(g
, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher
) * 8));
1560 state
->ciphersuite
= string_from_gstring(g
);
1563 state
->ciphersuite
= string_sprintf("%s:%s:%d",
1564 gnutls_protocol_get_name(protocol
),
1565 gnutls_cipher_suite_get_name(kx
, cipher
, mac
),
1566 (int) gnutls_cipher_get_key_size(cipher
) * 8);
1568 /* I don't see a way that spaces could occur, in the current GnuTLS
1569 code base, but it was a concern in the old code and perhaps older GnuTLS
1570 releases did return "TLS 1.0"; play it safe, just in case. */
1572 for (uschar
* p
= state
->ciphersuite
; *p
; p
++) if (isspace(*p
)) *p
= '-';
1575 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
1577 tlsp
->cipher
= state
->ciphersuite
;
1578 tlsp
->bits
= gnutls_cipher_get_key_size(cipher
) * 8;
1580 tlsp
->cipher_stdname
= cipher_stdname_kcm(kx
, cipher
, mac
);
1582 store_pool
= old_pool
;
1585 cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
);
1587 if (!cert_list
|| cert_list_size
== 0)
1589 DEBUG(D_tls
) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1590 cert_list
, cert_list_size
);
1591 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1592 return tls_error(US
"certificate verification failed",
1593 US
"no certificate received from peer", state
->host
, errstr
);
1597 if ((ct
= gnutls_certificate_type_get(session
)) != GNUTLS_CRT_X509
)
1599 const uschar
* ctn
= US
gnutls_certificate_type_get_name(ct
);
1601 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn
);
1602 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1603 return tls_error(US
"certificate verification not possible, unhandled type",
1604 ctn
, state
->host
, errstr
);
1608 #define exim_gnutls_peer_err(Label) \
1610 if (rc != GNUTLS_E_SUCCESS) \
1612 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1613 (Label), gnutls_strerror(rc)); \
1614 if (state->verify_requirement >= VERIFY_REQUIRED) \
1615 return tls_error_gnu((Label), rc, state->host, errstr); \
1620 rc
= import_cert(&cert_list
[0], &crt
);
1621 exim_gnutls_peer_err(US
"cert 0");
1623 state
->tlsp
->peercert
= state
->peercert
= crt
;
1626 rc
= gnutls_x509_crt_get_dn(crt
, NULL
, &sz
);
1627 if (rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
1629 exim_gnutls_peer_err(US
"getting size for cert DN failed");
1630 return FAIL
; /* should not happen */
1632 dn_buf
= store_get_perm(sz
, TRUE
); /* tainted */
1633 rc
= gnutls_x509_crt_get_dn(crt
, CS dn_buf
, &sz
);
1634 exim_gnutls_peer_err(US
"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1636 state
->peerdn
= dn_buf
;
1639 #undef exim_gnutls_peer_err
1645 /*************************************************
1646 * Verify peer certificate *
1647 *************************************************/
1649 /* Called from both server and client code.
1650 *Should* be using a callback registered with
1651 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1652 the peer information, but that's too new for some OSes.
1655 state exim_gnutls_state_st *
1656 errstr where to put an error message
1659 FALSE if the session should be rejected
1660 TRUE if the cert is okay or we just don't care
1664 verify_certificate(exim_gnutls_state_st
* state
, uschar
** errstr
)
1669 DEBUG(D_tls
) debug_printf("TLS: checking peer certificate\n");
1671 rc
= peer_status(state
, errstr
);
1673 if (state
->verify_requirement
== VERIFY_NONE
)
1676 if (rc
!= OK
|| !state
->peerdn
)
1678 verify
= GNUTLS_CERT_INVALID
;
1679 *errstr
= US
"certificate not supplied";
1685 if (state
->verify_requirement
== VERIFY_DANE
&& state
->host
)
1687 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1688 including talking to a DNS resolver. But we want to do that bit ourselves
1689 as the testsuite intercepts and fakes its own DNS environment. */
1694 const gnutls_datum_t
* certlist
=
1695 gnutls_certificate_get_peers(state
->session
, &lsize
);
1696 int usage
= tls_out
.tlsa_usage
;
1698 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1699 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1700 dane-verification separately so that we know which selector verified;
1701 then we know whether to do name-verification (needed for TA but not EE). */
1703 if (usage
== ((1<<DANESSL_USAGE_DANE_TA
) | (1<<DANESSL_USAGE_DANE_EE
)))
1704 { /* a mixed-usage bundle */
1709 for(nrec
= 0; state
->dane_data_len
[nrec
]; ) nrec
++;
1712 dd
= store_get(nrec
* sizeof(uschar
*), FALSE
);
1713 ddl
= store_get(nrec
* sizeof(int), FALSE
);
1716 if ((rc
= dane_state_init(&s
, 0)))
1719 for (usage
= DANESSL_USAGE_DANE_EE
;
1720 usage
>= DANESSL_USAGE_DANE_TA
; usage
--)
1721 { /* take records with this usage */
1722 for (j
= i
= 0; i
< nrec
; i
++)
1723 if (state
->dane_data
[i
][0] == usage
)
1725 dd
[j
] = state
->dane_data
[i
];
1726 ddl
[j
++] = state
->dane_data_len
[i
];
1733 if ((rc
= dane_raw_tlsa(s
, &r
, (char * const *)dd
, ddl
, 1, 0)))
1736 if ((rc
= dane_verify_crt_raw(s
, certlist
, lsize
,
1737 gnutls_certificate_type_get(state
->session
),
1739 usage
== DANESSL_USAGE_DANE_EE
1740 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE
: 0,
1744 debug_printf("TLSA record problem: %s\n", dane_strerror(rc
));
1746 else if (verify
== 0) /* verification passed */
1754 if (rc
) goto tlsa_prob
;
1759 if ( (rc
= dane_state_init(&s
, 0))
1760 || (rc
= dane_raw_tlsa(s
, &r
, state
->dane_data
, state
->dane_data_len
,
1762 || (rc
= dane_verify_crt_raw(s
, certlist
, lsize
,
1763 gnutls_certificate_type_get(state
->session
),
1765 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1766 usage
== (1 << DANESSL_USAGE_DANE_EE
)
1767 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE
: 0,
1776 if (verify
!= 0) /* verification failed */
1779 (void) dane_verification_status_print(verify
, &str
, 0);
1780 *errstr
= US str
.data
; /* don't bother to free */
1784 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1785 /* If a TA-mode TLSA record was used for verification we must additionally
1786 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1788 if (usage
& (1 << DANESSL_USAGE_DANE_EE
))
1791 state
->peer_dane_verified
= state
->peer_cert_verified
= TRUE
;
1794 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1795 /* Assume that the name on the A-record is the one that should be matching
1796 the cert. An alternate view is that the domain part of the email address
1797 is also permissible. */
1799 if (gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
,
1800 CS state
->host
->name
))
1802 state
->peer_dane_verified
= state
->peer_cert_verified
= TRUE
;
1807 #endif /*SUPPORT_DANE*/
1809 rc
= gnutls_certificate_verify_peers2(state
->session
, &verify
);
1812 /* Handle the result of verification. INVALID is set if any others are. */
1814 if (rc
< 0 || verify
& (GNUTLS_CERT_INVALID
|GNUTLS_CERT_REVOKED
))
1816 state
->peer_cert_verified
= FALSE
;
1819 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
1824 if (gnutls_certificate_verification_status_print(verify
,
1825 gnutls_certificate_type_get(state
->session
), &txt
, 0)
1826 == GNUTLS_E_SUCCESS
)
1828 debug_printf("%s\n", txt
.data
);
1829 gnutls_free(txt
.data
);
1833 *errstr
= verify
& GNUTLS_CERT_REVOKED
1834 ? US
"certificate revoked" : US
"certificate invalid";
1838 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1839 *errstr
, state
->peerdn
? state
->peerdn
: US
"<unset>");
1841 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1844 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1849 /* Client side, check the server's certificate name versus the name on the
1850 A-record for the connection we made. What to do for server side - what name
1851 to use for client? We document that there is no such checking for server
1854 if ( state
->exp_tls_verify_cert_hostnames
1855 && !gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
,
1856 CS state
->exp_tls_verify_cert_hostnames
)
1860 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1861 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1866 state
->peer_cert_verified
= TRUE
;
1867 DEBUG(D_tls
) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1868 state
->peerdn
? state
->peerdn
: US
"<unset>");
1872 state
->tlsp
->peerdn
= state
->peerdn
;
1877 *errstr
= string_sprintf("TLSA record problem: %s",
1878 rc
== DANE_E_REQUESTED_DATA_NOT_AVAILABLE
? "none usable" : dane_strerror(rc
));
1882 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_BAD_CERTIFICATE
);
1889 /* ------------------------------------------------------------------------ */
1892 /* Logging function which can be registered with
1893 * gnutls_global_set_log_function()
1894 * gnutls_global_set_log_level() 0..9
1896 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1898 exim_gnutls_logger_cb(int level
, const char *message
)
1900 size_t len
= strlen(message
);
1903 DEBUG(D_tls
) debug_printf("GnuTLS<%d> empty debug message\n", level
);
1906 DEBUG(D_tls
) debug_printf("GnuTLS<%d>: %s%s", level
, message
,
1907 message
[len
-1] == '\n' ? "" : "\n");
1912 /* Called after client hello, should handle SNI work.
1913 This will always set tls_sni (state->received_sni) if available,
1914 and may trigger presenting different certificates,
1915 if state->trigger_sni_changes is TRUE.
1917 Should be registered with
1918 gnutls_handshake_set_post_client_hello_function()
1920 "This callback must return 0 on success or a gnutls error code to terminate the
1923 For inability to get SNI information, we return 0.
1924 We only return non-zero if re-setup failed.
1925 Only used for server-side TLS.
1929 exim_sni_handling_cb(gnutls_session_t session
)
1931 char sni_name
[MAX_HOST_LEN
];
1932 size_t data_len
= MAX_HOST_LEN
;
1933 exim_gnutls_state_st
*state
= &state_server
;
1934 unsigned int sni_type
;
1936 uschar
* dummy_errstr
;
1938 rc
= gnutls_server_name_get(session
, sni_name
, &data_len
, &sni_type
, 0);
1939 if (rc
!= GNUTLS_E_SUCCESS
)
1942 if (rc
== GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
)
1943 debug_printf("TLS: no SNI presented in handshake.\n");
1945 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
1946 gnutls_strerror(rc
), rc
);
1950 if (sni_type
!= GNUTLS_NAME_DNS
)
1952 DEBUG(D_tls
) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type
);
1956 /* We now have a UTF-8 string in sni_name */
1957 old_pool
= store_pool
;
1958 store_pool
= POOL_PERM
;
1959 state
->received_sni
= string_copy_taint(US sni_name
, TRUE
);
1960 store_pool
= old_pool
;
1962 /* We set this one now so that variable expansions below will work */
1963 state
->tlsp
->sni
= state
->received_sni
;
1965 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name
,
1966 state
->trigger_sni_changes
? "" : " (unused for certificate selection)");
1968 if (!state
->trigger_sni_changes
)
1971 if ((rc
= tls_expand_session_files(state
, &dummy_errstr
)) != OK
)
1973 /* If the setup of certs/etc failed before handshake, TLS would not have
1974 been offered. The best we can do now is abort. */
1975 return GNUTLS_E_APPLICATION_ERROR_MIN
;
1978 rc
= tls_set_remaining_x509(state
, &dummy_errstr
);
1979 if (rc
!= OK
) return GNUTLS_E_APPLICATION_ERROR_MIN
;
1986 #ifndef DISABLE_OCSP
1989 server_ocsp_stapling_cb(gnutls_session_t session
, void * ptr
,
1990 gnutls_datum_t
* ocsp_response
)
1993 DEBUG(D_tls
) debug_printf("OCSP stapling callback: %s\n", US ptr
);
1995 if ((ret
= gnutls_load_file(ptr
, ocsp_response
)) < 0)
1997 DEBUG(D_tls
) debug_printf("Failed to load ocsp stapling file %s\n",
1999 tls_in
.ocsp
= OCSP_NOT_RESP
;
2000 return GNUTLS_E_NO_CERTIFICATE_STATUS
;
2003 tls_in
.ocsp
= OCSP_VFY_NOT_TRIED
;
2010 #ifndef DISABLE_EVENT
2012 We use this callback to get observability and detail-level control
2013 for an exim TLS connection (either direction), raising a tls:cert event
2014 for each cert in the chain presented by the peer. Any event
2015 can deny verification.
2017 Return 0 for the handshake to continue or non-zero to terminate.
2021 verify_cb(gnutls_session_t session
)
2023 const gnutls_datum_t
* cert_list
;
2024 unsigned int cert_list_size
= 0;
2025 gnutls_x509_crt_t crt
;
2028 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(session
);
2030 if ((cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
)))
2031 while (cert_list_size
--)
2033 if ((rc
= import_cert(&cert_list
[cert_list_size
], &crt
)) != GNUTLS_E_SUCCESS
)
2035 DEBUG(D_tls
) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2036 cert_list_size
, gnutls_strerror(rc
));
2040 state
->tlsp
->peercert
= crt
;
2041 if ((yield
= event_raise(state
->event_action
,
2042 US
"tls:cert", string_sprintf("%d", cert_list_size
))))
2044 log_write(0, LOG_MAIN
,
2045 "SSL verify denied by event-action: depth=%d: %s",
2046 cert_list_size
, yield
);
2047 return 1; /* reject */
2049 state
->tlsp
->peercert
= NULL
;
2059 ddump(gnutls_datum_t
* d
)
2061 gstring
* g
= string_get((d
->size
+1) * 2);
2062 uschar
* s
= d
->data
;
2063 for (unsigned i
= d
->size
; i
> 0; i
--, s
++)
2065 g
= string_catn(g
, US
"0123456789abcdef" + (*s
>> 4), 1);
2066 g
= string_catn(g
, US
"0123456789abcdef" + (*s
& 0xf), 1);
2072 post_handshake_debug(exim_gnutls_state_st
* state
)
2074 #ifdef SUPPORT_GNUTLS_SESS_DESC
2075 debug_printf("%s\n", gnutls_session_get_desc(state
->session
));
2077 #ifdef SUPPORT_GNUTLS_KEYLOG
2078 # ifdef GNUTLS_TLS1_3
2079 if (gnutls_protocol_get_version(state
->session
) < GNUTLS_TLS1_3
)
2084 gnutls_datum_t c
, s
;
2086 /* we only want the client random and the master secret */
2087 gnutls_session_get_random(state
->session
, &c
, &s
);
2088 gnutls_session_get_master_secret(state
->session
, &s
);
2091 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc
->ptr
, gc
->s
, (int)gs
->ptr
, gs
->s
);
2094 debug_printf("To get keying info for TLS1.3 is hard:\n"
2095 " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
2096 " add SSLKEYLOGFILE to keep_environment in the exim config\n"
2097 " run exim as root\n"
2098 " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n");
2103 #ifdef EXPERIMENTAL_TLS_RESUME
2105 tls_server_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
2106 unsigned incoming
, const gnutls_datum_t
* msg
)
2108 DEBUG(D_tls
) debug_printf("newticket cb\n");
2109 tls_in
.resumption
|= RESUME_CLIENT_REQUESTED
;
2114 tls_server_resume_prehandshake(exim_gnutls_state_st
* state
)
2116 /* Should the server offer session resumption? */
2117 tls_in
.resumption
= RESUME_SUPPORTED
;
2118 if (verify_check_host(&tls_resumption_hosts
) == OK
)
2121 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2122 an offered resumption is unacceptable. We lose one resumption per ticket
2123 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2124 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2125 least they go out in a single packet. */
2127 if (!(rc
= gnutls_session_ticket_enable_server(state
->session
,
2128 &server_sessticket_key
)))
2129 tls_in
.resumption
|= RESUME_SERVER_TICKET
;
2132 debug_printf("enabling session tickets: %s\n", US
gnutls_strerror(rc
));
2134 /* Try to tell if we see a ticket request */
2135 gnutls_handshake_set_hook_function(state
->session
,
2136 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
, GNUTLS_HOOK_POST
, tls_server_ticket_cb
);
2141 tls_server_resume_posthandshake(exim_gnutls_state_st
* state
)
2143 if (gnutls_session_resumption_requested(state
->session
))
2145 /* This tells us the client sent a full ticket. We use a
2146 callback on session-ticket request, elsewhere, to tell
2147 if a client asked for a ticket. */
2149 tls_in
.resumption
|= RESUME_CLIENT_SUGGESTED
;
2150 DEBUG(D_tls
) debug_printf("client requested resumption\n");
2152 if (gnutls_session_is_resumed(state
->session
))
2154 tls_in
.resumption
|= RESUME_USED
;
2155 DEBUG(D_tls
) debug_printf("Session resumed\n");
2159 /* ------------------------------------------------------------------------ */
2160 /* Exported functions */
2165 /*************************************************
2166 * Start a TLS session in a server *
2167 *************************************************/
2169 /* This is called when Exim is running as a server, after having received
2170 the STARTTLS command. It must respond to that command, and then negotiate
2174 require_ciphers list of allowed ciphers or NULL
2175 errstr pointer to error string
2177 Returns: OK on success
2178 DEFER for errors before the start of the negotiation
2179 FAIL for errors during the negotiation; the server can't
2184 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
2187 exim_gnutls_state_st
* state
= NULL
;
2189 /* Check for previous activation */
2190 if (tls_in
.active
.sock
>= 0)
2192 tls_error(US
"STARTTLS received after TLS started", US
"", NULL
, errstr
);
2193 smtp_printf("554 Already in TLS\r\n", FALSE
);
2197 /* Initialize the library. If it fails, it will already have logged the error
2198 and sent an SMTP response. */
2200 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a server\n");
2202 if ((rc
= tls_init(NULL
, tls_certificate
, tls_privatekey
,
2203 NULL
, tls_verify_certificates
, tls_crl
,
2204 require_ciphers
, &state
, &tls_in
, errstr
)) != OK
) return rc
;
2206 #ifdef EXPERIMENTAL_TLS_RESUME
2207 tls_server_resume_prehandshake(state
);
2210 /* If this is a host for which certificate verification is mandatory or
2211 optional, set up appropriately. */
2213 if (verify_check_host(&tls_verify_hosts
) == OK
)
2216 debug_printf("TLS: a client certificate will be required.\n");
2217 state
->verify_requirement
= VERIFY_REQUIRED
;
2218 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2220 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
2223 debug_printf("TLS: a client certificate will be requested but not required.\n");
2224 state
->verify_requirement
= VERIFY_OPTIONAL
;
2225 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2230 debug_printf("TLS: a client certificate will not be requested.\n");
2231 state
->verify_requirement
= VERIFY_NONE
;
2232 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2235 #ifndef DISABLE_EVENT
2238 state
->event_action
= event_action
;
2239 gnutls_session_set_ptr(state
->session
, state
);
2240 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2244 /* Register SNI handling; always, even if not in tls_certificate, so that the
2245 expansion variable $tls_sni is always available. */
2247 gnutls_handshake_set_post_client_hello_function(state
->session
,
2248 exim_sni_handling_cb
);
2250 /* Set context and tell client to go ahead, except in the case of TLS startup
2251 on connection, where outputting anything now upsets the clients and tends to
2252 make them disconnect. We need to have an explicit fflush() here, to force out
2253 the response. Other smtp_printf() calls do not need it, because in non-TLS
2254 mode, the fflush() happens when smtp_getc() is called. */
2256 if (!state
->tlsp
->on_connect
)
2258 smtp_printf("220 TLS go ahead\r\n", FALSE
);
2262 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2263 that the GnuTLS library doesn't.
2264 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2265 to set (and clear down afterwards) up a pull-timeout callback function that does
2266 a select, so we're no better off unless avoiding signals becomes an issue. */
2268 gnutls_transport_set_ptr2(state
->session
,
2269 (gnutls_transport_ptr_t
)(long) fileno(smtp_in
),
2270 (gnutls_transport_ptr_t
)(long) fileno(smtp_out
));
2271 state
->fd_in
= fileno(smtp_in
);
2272 state
->fd_out
= fileno(smtp_out
);
2274 sigalrm_seen
= FALSE
;
2275 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2277 rc
= gnutls_handshake(state
->session
);
2278 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
2281 if (rc
!= GNUTLS_E_SUCCESS
)
2283 /* It seems that, except in the case of a timeout, we have to close the
2284 connection right here; otherwise if the other end is running OpenSSL it hangs
2285 until the server times out. */
2289 tls_error(US
"gnutls_handshake", US
"timed out", NULL
, errstr
);
2290 gnutls_db_remove_session(state
->session
);
2294 tls_error_gnu(US
"gnutls_handshake", rc
, NULL
, errstr
);
2295 (void) gnutls_alert_send_appropriate(state
->session
, rc
);
2296 gnutls_deinit(state
->session
);
2297 gnutls_certificate_free_credentials(state
->x509_cred
);
2299 shutdown(state
->fd_out
, SHUT_WR
);
2300 for (int i
= 1024; fgetc(smtp_in
) != EOF
&& i
> 0; ) i
--; /* drain skt */
2301 (void)fclose(smtp_out
);
2302 (void)fclose(smtp_in
);
2303 smtp_out
= smtp_in
= NULL
;
2309 #ifdef EXPERIMENTAL_TLS_RESUME
2310 tls_server_resume_posthandshake(state
);
2313 DEBUG(D_tls
) post_handshake_debug(state
);
2315 /* Verify after the fact */
2317 if (!verify_certificate(state
, errstr
))
2319 if (state
->verify_requirement
!= VERIFY_OPTIONAL
)
2321 (void) tls_error(US
"certificate verification failed", *errstr
, NULL
, errstr
);
2325 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2329 /* Sets various Exim expansion variables; always safe within server */
2331 extract_exim_vars_from_tls_state(state
);
2333 /* TLS has been set up. Adjust the input functions to read via TLS,
2334 and initialize appropriately. */
2336 state
->xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2338 receive_getc
= tls_getc
;
2339 receive_getbuf
= tls_getbuf
;
2340 receive_get_cache
= tls_get_cache
;
2341 receive_ungetc
= tls_ungetc
;
2342 receive_feof
= tls_feof
;
2343 receive_ferror
= tls_ferror
;
2344 receive_smtp_buffered
= tls_smtp_buffered
;
2353 tls_client_setup_hostname_checks(host_item
* host
, exim_gnutls_state_st
* state
,
2354 smtp_transport_options_block
* ob
)
2356 if (verify_check_given_host(CUSS
&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2358 state
->exp_tls_verify_cert_hostnames
=
2360 string_domain_utf8_to_alabel(host
->name
, NULL
);
2365 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2366 state
->exp_tls_verify_cert_hostnames
);
2374 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2375 GnuTLS-DANE's preferred format. Hang it on the state str for later
2376 use in DANE verification.
2378 We point at the dnsa data not copy it, so it must remain valid until
2379 after verification is done.*/
2382 dane_tlsa_load(exim_gnutls_state_st
* state
, dns_answer
* dnsa
)
2386 const char ** dane_data
;
2387 int * dane_data_len
;
2390 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2391 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2392 ) if (rr
->type
== T_TLSA
) i
++;
2394 dane_data
= store_get(i
* sizeof(uschar
*), FALSE
);
2395 dane_data_len
= store_get(i
* sizeof(int), FALSE
);
2398 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2399 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2400 ) if (rr
->type
== T_TLSA
&& rr
->size
> 3)
2402 const uschar
* p
= rr
->data
;
2403 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
2404 uint8_t usage
= p
[0], sel
= p
[1], type
= p
[2];
2407 debug_printf("TLSA: %d %d %d size %d\n", usage
, sel
, type
, rr
->size
);
2409 if ( (usage
!= DANESSL_USAGE_DANE_TA
&& usage
!= DANESSL_USAGE_DANE_EE
)
2410 || (sel
!= 0 && sel
!= 1)
2415 case 0: /* Full: cannot check at present */
2417 case 1: if (rr
->size
!= 3 + 256/8) continue; /* sha2-256 */
2419 case 2: if (rr
->size
!= 3 + 512/8) continue; /* sha2-512 */
2424 tls_out
.tlsa_usage
|= 1<<usage
;
2425 dane_data
[i
] = CS p
;
2426 dane_data_len
[i
++] = rr
->size
;
2429 if (!i
) return FALSE
;
2431 dane_data
[i
] = NULL
;
2432 dane_data_len
[i
] = 0;
2434 state
->dane_data
= (char * const *)dane_data
;
2435 state
->dane_data_len
= dane_data_len
;
2442 #ifdef EXPERIMENTAL_TLS_RESUME
2443 /* On the client, get any stashed session for the given IP from hints db
2444 and apply it to the ssl-connection for attempted resumption. Although
2445 there is a gnutls_session_ticket_enable_client() interface it is
2446 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
2447 by deafult". There seems to be no way to disable them, so even hosts not
2448 enabled by the transport option will be sent a ticket request. We will
2449 however avoid storing and retrieving session information. */
2452 tls_retrieve_session(tls_support
* tlsp
, gnutls_session_t session
,
2453 host_item
* host
, smtp_transport_options_block
* ob
)
2455 tlsp
->resumption
= RESUME_SUPPORTED
;
2456 if (verify_check_given_host(CUSS
&ob
->tls_resumption_hosts
, host
) == OK
)
2458 dbdata_tls_session
* dt
;
2460 open_db dbblock
, * dbm_file
;
2463 debug_printf("check for resumable session for %s\n", host
->address
);
2464 tlsp
->host_resumable
= TRUE
;
2465 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
2466 if ((dbm_file
= dbfn_open(US
"tls", O_RDONLY
, &dbblock
, FALSE
, FALSE
)))
2468 /* Key for the db is the IP. We'd like to filter the retrieved session
2469 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
2471 if ((dt
= dbfn_read_with_length(dbm_file
, host
->address
, &len
)))
2472 if (!(rc
= gnutls_session_set_data(session
,
2473 CUS dt
->session
, (size_t)len
- sizeof(dbdata_tls_session
))))
2475 DEBUG(D_tls
) debug_printf("good session\n");
2476 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
2478 else DEBUG(D_tls
) debug_printf("setting session resumption data: %s\n",
2479 US
gnutls_strerror(rc
));
2480 dbfn_close(dbm_file
);
2487 tls_save_session(tls_support
* tlsp
, gnutls_session_t session
, const host_item
* host
)
2489 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
2490 but this flag is not set until the second. TLS 1.3 it's the other way about.
2491 Keep both calls as the session data cannot be extracted before handshake
2494 if (gnutls_session_get_flags(session
) & GNUTLS_SFLAGS_SESSION_TICKET
)
2499 DEBUG(D_tls
) debug_printf("server offered session ticket\n");
2500 tlsp
->ticket_received
= TRUE
;
2501 tlsp
->resumption
|= RESUME_SERVER_TICKET
;
2503 if (tlsp
->host_resumable
)
2504 if (!(rc
= gnutls_session_get_data2(session
, &tkt
)))
2506 open_db dbblock
, * dbm_file
;
2507 int dlen
= sizeof(dbdata_tls_session
) + tkt
.size
;
2508 dbdata_tls_session
* dt
= store_get(dlen
, TRUE
);
2510 DEBUG(D_tls
) debug_printf("session data size %u\n", (unsigned)tkt
.size
);
2511 memcpy(dt
->session
, tkt
.data
, tkt
.size
);
2512 gnutls_free(tkt
.data
);
2514 if ((dbm_file
= dbfn_open(US
"tls", O_RDWR
, &dbblock
, FALSE
, FALSE
)))
2516 /* key for the db is the IP */
2517 dbfn_delete(dbm_file
, host
->address
);
2518 dbfn_write(dbm_file
, host
->address
, dt
, dlen
);
2519 dbfn_close(dbm_file
);
2522 debug_printf("wrote session db (len %u)\n", (unsigned)dlen
);
2526 debug_printf("extract session data: %s\n", US
gnutls_strerror(rc
));
2531 /* With a TLS1.3 session, the ticket(s) are not seen until
2532 the first data read is attempted. And there's often two of them.
2533 Pick them up with this callback. We are also called for 1.2
2537 tls_client_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
2538 unsigned incoming
, const gnutls_datum_t
* msg
)
2540 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(sess
);
2541 tls_support
* tlsp
= state
->tlsp
;
2543 DEBUG(D_tls
) debug_printf("newticket cb\n");
2545 if (!tlsp
->ticket_received
)
2546 tls_save_session(tlsp
, sess
, state
->host
);
2552 tls_client_resume_prehandshake(exim_gnutls_state_st
* state
,
2553 tls_support
* tlsp
, host_item
* host
,
2554 smtp_transport_options_block
* ob
)
2556 gnutls_session_set_ptr(state
->session
, state
);
2557 gnutls_handshake_set_hook_function(state
->session
,
2558 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
, GNUTLS_HOOK_POST
, tls_client_ticket_cb
);
2560 tls_retrieve_session(tlsp
, state
->session
, host
, ob
);
2564 tls_client_resume_posthandshake(exim_gnutls_state_st
* state
,
2565 tls_support
* tlsp
, host_item
* host
)
2567 if (gnutls_session_is_resumed(state
->session
))
2569 DEBUG(D_tls
) debug_printf("Session resumed\n");
2570 tlsp
->resumption
|= RESUME_USED
;
2573 tls_save_session(tlsp
, state
->session
, host
);
2575 #endif /* EXPERIMENTAL_TLS_RESUME */
2578 /*************************************************
2579 * Start a TLS session in a client *
2580 *************************************************/
2582 /* Called from the smtp transport after STARTTLS has been accepted.
2585 cctx connection context
2586 conn_args connection details
2587 cookie datum for randomness (not used)
2588 tlsp record details of channel configuration here; must be non-NULL
2589 errstr error string pointer
2591 Returns: TRUE for success with TLS session context set in smtp context,
2596 tls_client_start(client_conn_ctx
* cctx
, smtp_connect_args
* conn_args
,
2597 void * cookie ARG_UNUSED
,
2598 tls_support
* tlsp
, uschar
** errstr
)
2600 host_item
* host
= conn_args
->host
; /* for msgs and option-tests */
2601 transport_instance
* tb
= conn_args
->tblock
; /* always smtp or NULL */
2602 smtp_transport_options_block
* ob
= tb
2603 ? (smtp_transport_options_block
*)tb
->options_block
2604 : &smtp_transport_option_defaults
;
2606 exim_gnutls_state_st
* state
= NULL
;
2607 uschar
* cipher_list
= NULL
;
2609 #ifndef DISABLE_OCSP
2611 verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
;
2612 BOOL request_ocsp
= require_ocsp
? TRUE
2613 : verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2616 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx
->sock
);
2619 /* If dane is flagged, have either request or require dane for this host, and
2620 a TLSA record found. Therefore, dane verify required. Which implies cert must
2621 be requested and supplied, dane verify must pass, and cert verify irrelevant
2622 (incl. hostnames), and (caller handled) require_tls */
2624 if (conn_args
->dane
&& ob
->dane_require_tls_ciphers
)
2626 /* not using expand_check_tlsvar because not yet in state */
2627 if (!expand_check(ob
->dane_require_tls_ciphers
, US
"dane_require_tls_ciphers",
2628 &cipher_list
, errstr
))
2630 cipher_list
= cipher_list
&& *cipher_list
2631 ? ob
->dane_require_tls_ciphers
: ob
->tls_require_ciphers
;
2636 cipher_list
= ob
->tls_require_ciphers
;
2638 if (tls_init(host
, ob
->tls_certificate
, ob
->tls_privatekey
,
2639 ob
->tls_sni
, ob
->tls_verify_certificates
, ob
->tls_crl
,
2640 cipher_list
, &state
, tlsp
, errstr
) != OK
)
2644 int dh_min_bits
= ob
->tls_dh_min_bits
;
2645 if (dh_min_bits
< EXIM_CLIENT_DH_MIN_MIN_BITS
)
2648 debug_printf("WARNING: tls_dh_min_bits far too low,"
2649 " clamping %d up to %d\n",
2650 dh_min_bits
, EXIM_CLIENT_DH_MIN_MIN_BITS
);
2651 dh_min_bits
= EXIM_CLIENT_DH_MIN_MIN_BITS
;
2654 DEBUG(D_tls
) debug_printf("Setting D-H prime minimum"
2655 " acceptable bits to %d\n",
2657 gnutls_dh_set_prime_bits(state
->session
, dh_min_bits
);
2660 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2661 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2662 the specified host patterns if one of them is defined */
2665 if (conn_args
->dane
&& dane_tlsa_load(state
, &conn_args
->tlsa_dnsa
))
2668 debug_printf("TLS: server certificate DANE required.\n");
2669 state
->verify_requirement
= VERIFY_DANE
;
2670 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2674 if ( ( state
->exp_tls_verify_certificates
2675 && !ob
->tls_verify_hosts
2676 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2678 || verify_check_given_host(CUSS
&ob
->tls_verify_hosts
, host
) == OK
2681 tls_client_setup_hostname_checks(host
, state
, ob
);
2683 debug_printf("TLS: server certificate verification required.\n");
2684 state
->verify_requirement
= VERIFY_REQUIRED
;
2685 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2687 else if (verify_check_given_host(CUSS
&ob
->tls_try_verify_hosts
, host
) == OK
)
2689 tls_client_setup_hostname_checks(host
, state
, ob
);
2691 debug_printf("TLS: server certificate verification optional.\n");
2692 state
->verify_requirement
= VERIFY_OPTIONAL
;
2693 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2698 debug_printf("TLS: server certificate verification not required.\n");
2699 state
->verify_requirement
= VERIFY_NONE
;
2700 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2703 #ifndef DISABLE_OCSP
2704 /* supported since GnuTLS 3.1.3 */
2707 DEBUG(D_tls
) debug_printf("TLS: will request OCSP stapling\n");
2708 if ((rc
= gnutls_ocsp_status_request_enable_client(state
->session
,
2709 NULL
, 0, NULL
)) != OK
)
2711 tls_error_gnu(US
"cert-status-req", rc
, state
->host
, errstr
);
2714 tlsp
->ocsp
= OCSP_NOT_RESP
;
2718 #ifdef EXPERIMENTAL_TLS_RESUME
2719 tls_client_resume_prehandshake(state
, tlsp
, host
, ob
);
2722 #ifndef DISABLE_EVENT
2723 if (tb
&& tb
->event_action
)
2725 state
->event_action
= tb
->event_action
;
2726 gnutls_session_set_ptr(state
->session
, state
);
2727 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2731 gnutls_transport_set_ptr(state
->session
, (gnutls_transport_ptr_t
)(long) cctx
->sock
);
2732 state
->fd_in
= cctx
->sock
;
2733 state
->fd_out
= cctx
->sock
;
2735 DEBUG(D_tls
) debug_printf("about to gnutls_handshake\n");
2736 /* There doesn't seem to be a built-in timeout on connection. */
2738 sigalrm_seen
= FALSE
;
2739 ALARM(ob
->command_timeout
);
2741 rc
= gnutls_handshake(state
->session
);
2742 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
2745 if (rc
!= GNUTLS_E_SUCCESS
)
2749 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_USER_CANCELED
);
2750 tls_error(US
"gnutls_handshake", US
"timed out", state
->host
, errstr
);
2753 tls_error_gnu(US
"gnutls_handshake", rc
, state
->host
, errstr
);
2757 DEBUG(D_tls
) post_handshake_debug(state
);
2761 if (!verify_certificate(state
, errstr
))
2763 tls_error(US
"certificate verification failed", *errstr
, state
->host
, errstr
);
2767 #ifndef DISABLE_OCSP
2772 gnutls_datum_t stapling
;
2773 gnutls_ocsp_resp_t resp
;
2774 gnutls_datum_t printed
;
2775 if ( (rc
= gnutls_ocsp_status_request_get(state
->session
, &stapling
)) == 0
2776 && (rc
= gnutls_ocsp_resp_init(&resp
)) == 0
2777 && (rc
= gnutls_ocsp_resp_import(resp
, &stapling
)) == 0
2778 && (rc
= gnutls_ocsp_resp_print(resp
, GNUTLS_OCSP_PRINT_FULL
, &printed
)) == 0
2781 debug_printf("%.4096s", printed
.data
);
2782 gnutls_free(printed
.data
);
2785 (void) tls_error_gnu(US
"ocsp decode", rc
, state
->host
, errstr
);
2788 if (gnutls_ocsp_status_request_is_checked(state
->session
, 0) == 0)
2790 tlsp
->ocsp
= OCSP_FAILED
;
2791 tls_error(US
"certificate status check failed", NULL
, state
->host
, errstr
);
2797 DEBUG(D_tls
) debug_printf("Passed OCSP checking\n");
2798 tlsp
->ocsp
= OCSP_VFIED
;
2803 #ifdef EXPERIMENTAL_TLS_RESUME
2804 tls_client_resume_posthandshake(state
, tlsp
, host
);
2807 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2809 extract_exim_vars_from_tls_state(state
);
2811 cctx
->tls_ctx
= state
;
2818 /*************************************************
2819 * Close down a TLS session *
2820 *************************************************/
2822 /* This is also called from within a delivery subprocess forked from the
2823 daemon, to shut down the TLS library, without actually doing a shutdown (which
2824 would tamper with the TLS session in the parent process).
2827 ct_ctx client context pointer, or NULL for the one global server context
2828 shutdown 1 if TLS close-alert is to be sent,
2829 2 if also response to be waited for
2835 tls_close(void * ct_ctx
, int shutdown
)
2837 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
2838 tls_support
* tlsp
= state
->tlsp
;
2840 if (!tlsp
|| tlsp
->active
.sock
< 0) return; /* TLS was not active */
2844 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS%s\n",
2845 shutdown
> 1 ? " (with response-wait)" : "");
2848 gnutls_bye(state
->session
, shutdown
> 1 ? GNUTLS_SHUT_RDWR
: GNUTLS_SHUT_WR
);
2852 if (!ct_ctx
) /* server */
2854 receive_getc
= smtp_getc
;
2855 receive_getbuf
= smtp_getbuf
;
2856 receive_get_cache
= smtp_get_cache
;
2857 receive_ungetc
= smtp_ungetc
;
2858 receive_feof
= smtp_feof
;
2859 receive_ferror
= smtp_ferror
;
2860 receive_smtp_buffered
= smtp_buffered
;
2863 gnutls_deinit(state
->session
);
2864 gnutls_certificate_free_credentials(state
->x509_cred
);
2866 tlsp
->active
.sock
= -1;
2867 tlsp
->active
.tls_ctx
= NULL
;
2868 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
2869 tls_channelbinding_b64
= NULL
;
2872 if (state
->xfer_buffer
) store_free(state
->xfer_buffer
);
2873 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
2880 tls_refill(unsigned lim
)
2882 exim_gnutls_state_st
* state
= &state_server
;
2885 DEBUG(D_tls
) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2886 state
->session
, state
->xfer_buffer
, ssl_xfer_buffer_size
);
2888 sigalrm_seen
= FALSE
;
2889 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2892 inbytes
= gnutls_record_recv(state
->session
, state
->xfer_buffer
,
2893 MIN(ssl_xfer_buffer_size
, lim
));
2894 while (inbytes
== GNUTLS_E_AGAIN
);
2896 if (smtp_receive_timeout
> 0) ALARM_CLR(0);
2898 if (had_command_timeout
) /* set by signal handler */
2899 smtp_command_timeout_exit(); /* does not return */
2900 if (had_command_sigterm
)
2901 smtp_command_sigterm_exit();
2902 if (had_data_timeout
)
2903 smtp_data_timeout_exit();
2904 if (had_data_sigint
)
2905 smtp_data_sigint_exit();
2907 /* Timeouts do not get this far. A zero-byte return appears to mean that the
2908 TLS session has been closed down, not that the socket itself has been closed
2909 down. Revert to non-TLS handling. */
2913 DEBUG(D_tls
) debug_printf("Got tls read timeout\n");
2914 state
->xfer_error
= TRUE
;
2918 else if (inbytes
== 0)
2920 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
2921 tls_close(NULL
, TLS_NO_SHUTDOWN
);
2925 /* Handle genuine errors */
2927 else if (inbytes
< 0)
2929 DEBUG(D_tls
) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__
);
2930 record_io_error(state
, (int) inbytes
, US
"recv", NULL
);
2931 state
->xfer_error
= TRUE
;
2934 #ifndef DISABLE_DKIM
2935 dkim_exim_verify_feed(state
->xfer_buffer
, inbytes
);
2937 state
->xfer_buffer_hwm
= (int) inbytes
;
2938 state
->xfer_buffer_lwm
= 0;
2942 /*************************************************
2943 * TLS version of getc *
2944 *************************************************/
2946 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2947 it refills the buffer via the GnuTLS reading function.
2948 Only used by the server-side TLS.
2950 This feeds DKIM and should be used for all message-body reads.
2952 Arguments: lim Maximum amount to read/buffer
2953 Returns: the next character or EOF
2957 tls_getc(unsigned lim
)
2959 exim_gnutls_state_st
* state
= &state_server
;
2961 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
2962 if (!tls_refill(lim
))
2963 return state
->xfer_error
? EOF
: smtp_getc(lim
);
2965 /* Something in the buffer; return next uschar */
2967 return state
->xfer_buffer
[state
->xfer_buffer_lwm
++];
2971 tls_getbuf(unsigned * len
)
2973 exim_gnutls_state_st
* state
= &state_server
;
2977 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
2978 if (!tls_refill(*len
))
2980 if (!state
->xfer_error
) return smtp_getbuf(len
);
2985 if ((size
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
) > *len
)
2987 buf
= &state
->xfer_buffer
[state
->xfer_buffer_lwm
];
2988 state
->xfer_buffer_lwm
+= size
;
2997 #ifndef DISABLE_DKIM
2998 exim_gnutls_state_st
* state
= &state_server
;
2999 int n
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
;
3001 dkim_exim_verify_feed(state
->xfer_buffer
+state
->xfer_buffer_lwm
, n
);
3007 tls_could_read(void)
3009 return state_server
.xfer_buffer_lwm
< state_server
.xfer_buffer_hwm
3010 || gnutls_record_check_pending(state_server
.session
) > 0;
3016 /*************************************************
3017 * Read bytes from TLS channel *
3018 *************************************************/
3020 /* This does not feed DKIM, so if the caller uses this for reading message body,
3021 then the caller must feed DKIM.
3024 ct_ctx client context pointer, or NULL for the one global server context
3028 Returns: the number of bytes read
3029 -1 after a failed read, including EOF
3033 tls_read(void * ct_ctx
, uschar
*buff
, size_t len
)
3035 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3041 if (state
->xfer_buffer_lwm
< state
->xfer_buffer_hwm
)
3043 debug_printf("*** PROBABLY A BUG *** " \
3044 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3045 state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
);
3048 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT
")\n",
3049 state
->session
, buff
, len
);
3052 inbytes
= gnutls_record_recv(state
->session
, buff
, len
);
3053 while (inbytes
== GNUTLS_E_AGAIN
);
3055 if (inbytes
> 0) return inbytes
;
3058 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
3062 DEBUG(D_tls
) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__
);
3063 record_io_error(state
, (int)inbytes
, US
"recv", NULL
);
3072 /*************************************************
3073 * Write bytes down TLS channel *
3074 *************************************************/
3078 ct_ctx client context pointer, or NULL for the one global server context
3081 more more data expected soon
3083 Returns: the number of bytes after a successful write,
3084 -1 after a failed write
3088 tls_write(void * ct_ctx
, const uschar
* buff
, size_t len
, BOOL more
)
3092 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3094 static BOOL corked
= FALSE
;
3096 if (more
&& !corked
) gnutls_record_cork(state
->session
);
3099 DEBUG(D_tls
) debug_printf("%s(%p, " SIZE_T_FMT
"%s)\n", __FUNCTION__
,
3100 buff
, left
, more
? ", more" : "");
3104 DEBUG(D_tls
) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT
")\n",
3108 outbytes
= gnutls_record_send(state
->session
, buff
, left
);
3109 while (outbytes
== GNUTLS_E_AGAIN
);
3111 DEBUG(D_tls
) debug_printf("outbytes=" SSIZE_T_FMT
"\n", outbytes
);
3114 DEBUG(D_tls
) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__
);
3115 record_io_error(state
, outbytes
, US
"send", NULL
);
3120 record_io_error(state
, 0, US
"send", US
"TLS channel closed on write");
3131 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT
") than INT_MAX\n",
3139 if (!more
) (void) gnutls_record_uncork(state
->session
, 0);
3150 /*************************************************
3151 * Random number generation *
3152 *************************************************/
3154 /* Pseudo-random number generation. The result is not expected to be
3155 cryptographically strong but not so weak that someone will shoot themselves
3156 in the foot using it as a nonce in input in some email header scheme or
3157 whatever weirdness they'll twist this into. The result should handle fork()
3158 and avoid repeating sequences. OpenSSL handles that for us.
3162 Returns a random number in range [0, max-1]
3165 #ifdef HAVE_GNUTLS_RND
3167 vaguely_random_number(int max
)
3171 uschar smallbuf
[sizeof(r
)];
3176 needed_len
= sizeof(r
);
3177 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3178 asked for a number less than 10. */
3180 for (r
= max
, i
= 0; r
; ++i
)
3186 i
= gnutls_rnd(GNUTLS_RND_NONCE
, smallbuf
, needed_len
);
3189 DEBUG(D_all
) debug_printf("gnutls_rnd() failed, using fallback.\n");
3190 return vaguely_random_number_fallback(max
);
3193 for (uschar
* p
= smallbuf
; needed_len
; --needed_len
, ++p
)
3196 /* We don't particularly care about weighted results; if someone wants
3197 * smooth distribution and cares enough then they should submit a patch then. */
3200 #else /* HAVE_GNUTLS_RND */
3202 vaguely_random_number(int max
)
3204 return vaguely_random_number_fallback(max
);
3206 #endif /* HAVE_GNUTLS_RND */
3211 /*************************************************
3212 * Let tls_require_ciphers be checked at startup *
3213 *************************************************/
3215 /* The tls_require_ciphers option, if set, must be something which the
3218 Returns: NULL on success, or error message
3222 tls_validate_require_cipher(void)
3225 uschar
*expciphers
= NULL
;
3226 gnutls_priority_t priority_cache
;
3228 uschar
* dummy_errstr
;
3230 #define validate_check_rc(Label) do { \
3231 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3232 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3233 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3235 if (exim_gnutls_base_init_done
)
3236 log_write(0, LOG_MAIN
|LOG_PANIC
,
3237 "already initialised GnuTLS, Exim developer bug");
3239 #ifdef HAVE_GNUTLS_PKCS11
3240 if (!gnutls_allow_auto_pkcs11
)
3242 rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
);
3243 validate_check_rc(US
"gnutls_pkcs11_init");
3246 rc
= gnutls_global_init();
3247 validate_check_rc(US
"gnutls_global_init()");
3248 exim_gnutls_base_init_done
= TRUE
;
3250 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
3251 return_deinit(NULL
);
3253 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
3255 return_deinit(US
"failed to expand tls_require_ciphers");
3257 if (!(expciphers
&& *expciphers
))
3258 return_deinit(NULL
);
3261 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
3263 rc
= gnutls_priority_init(&priority_cache
, CS expciphers
, &errpos
);
3264 validate_check_rc(string_sprintf(
3265 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3266 expciphers
, errpos
- CS expciphers
, errpos
));
3268 #undef return_deinit
3269 #undef validate_check_rc
3270 gnutls_global_deinit();
3278 /*************************************************
3279 * Report the library versions. *
3280 *************************************************/
3282 /* See a description in tls-openssl.c for an explanation of why this exists.
3284 Arguments: a FILE* to print the results to
3289 tls_version_report(FILE *f
)
3291 fprintf(f
, "Library version: GnuTLS: Compile: %s\n"
3294 gnutls_check_version(NULL
));
3297 #endif /*!MACRO_PREDEF*/
3300 /* End of tls-gnu.c */