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
= 3600; /* One hour */
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
= 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
= 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
);
1149 return tls_error_gnu(US
"setting certificate trust", cert_count
, host
, errstr
);
1151 debug_printf("Added %d certificate authorities.\n", cert_count
);
1153 if (state
->tls_crl
&& *state
->tls_crl
&&
1154 state
->exp_tls_crl
&& *state
->exp_tls_crl
)
1156 DEBUG(D_tls
) debug_printf("loading CRL file = %s\n", state
->exp_tls_crl
);
1157 if ((cert_count
= gnutls_certificate_set_x509_crl_file(state
->x509_cred
,
1158 CS state
->exp_tls_crl
, GNUTLS_X509_FMT_PEM
)) < 0)
1159 return tls_error_gnu(US
"gnutls_certificate_set_x509_crl_file",
1160 cert_count
, host
, errstr
);
1162 DEBUG(D_tls
) debug_printf("Processed %d CRLs.\n", cert_count
);
1171 /*************************************************
1172 * Set X.509 state variables *
1173 *************************************************/
1175 /* In GnuTLS, the registered cert/key are not replaced by a later
1176 set of a cert/key, so for SNI support we need a whole new x509_cred
1177 structure. Which means various other non-re-expanded pieces of state
1178 need to be re-set in the new struct, so the setting logic is pulled
1182 state exim_gnutls_state_st *
1183 errstr error string pointer
1185 Returns: OK/DEFER/FAIL
1189 tls_set_remaining_x509(exim_gnutls_state_st
*state
, uschar
** errstr
)
1192 const host_item
*host
= state
->host
; /* macro should be reconsidered? */
1194 /* Create D-H parameters, or read them from the cache file. This function does
1195 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1196 client-side params. */
1200 if (!dh_server_params
)
1201 if ((rc
= init_server_dh(errstr
)) != OK
) return rc
;
1202 gnutls_certificate_set_dh_params(state
->x509_cred
, dh_server_params
);
1205 /* Link the credentials to the session. */
1207 if ((rc
= gnutls_credentials_set(state
->session
,
1208 GNUTLS_CRD_CERTIFICATE
, state
->x509_cred
)))
1209 return tls_error_gnu(US
"gnutls_credentials_set", rc
, host
, errstr
);
1214 /*************************************************
1215 * Initialize for GnuTLS *
1216 *************************************************/
1219 #ifndef DISABLE_OCSP
1222 tls_is_buggy_ocsp(void)
1225 uschar maj
, mid
, mic
;
1227 s
= CUS
gnutls_check_version(NULL
);
1231 while (*s
&& *s
!= '.') s
++;
1232 mid
= atoi(CCS
++s
);
1239 while (*s
&& *s
!= '.') s
++;
1240 mic
= atoi(CCS
++s
);
1241 return mic
<= (mid
== 3 ? 16 : 3);
1250 /* Called from both server and client code. In the case of a server, errors
1251 before actual TLS negotiation return DEFER.
1254 host connected host, if client; NULL if server
1255 certificate certificate file
1256 privatekey private key file
1257 sni TLS SNI to send, sometimes when client; else NULL
1260 require_ciphers tls_require_ciphers setting
1261 caller_state returned state-info structure
1262 errstr error string pointer
1264 Returns: OK/DEFER/FAIL
1269 const host_item
*host
,
1270 const uschar
*certificate
,
1271 const uschar
*privatekey
,
1275 const uschar
*require_ciphers
,
1276 exim_gnutls_state_st
**caller_state
,
1280 exim_gnutls_state_st
* state
;
1283 const char * errpos
;
1286 if (!exim_gnutls_base_init_done
)
1288 DEBUG(D_tls
) debug_printf("GnuTLS global init required.\n");
1290 #ifdef HAVE_GNUTLS_PKCS11
1291 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1292 which loads modules from a config file, which sounds good and may be wanted
1293 by some sysadmin, but also means in common configurations that GNOME keyring
1294 environment variables are used and so breaks for users calling mailq.
1295 To prevent this, we init PKCS11 first, which is the documented approach. */
1296 if (!gnutls_allow_auto_pkcs11
)
1297 if ((rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
)))
1298 return tls_error_gnu(US
"gnutls_pkcs11_init", rc
, host
, errstr
);
1301 if ((rc
= gnutls_global_init()))
1302 return tls_error_gnu(US
"gnutls_global_init", rc
, host
, errstr
);
1304 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1307 gnutls_global_set_log_function(exim_gnutls_logger_cb
);
1308 /* arbitrarily chosen level; bump up to 9 for more */
1309 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL
);
1313 #ifndef DISABLE_OCSP
1314 if (tls_ocsp_file
&& (gnutls_buggy_ocsp
= tls_is_buggy_ocsp()))
1315 log_write(0, LOG_MAIN
, "OCSP unusable with this GnuTLS library version");
1318 exim_gnutls_base_init_done
= TRUE
;
1323 /* For client-side sessions we allocate a context. This lets us run
1324 several in parallel. */
1325 int old_pool
= store_pool
;
1326 store_pool
= POOL_PERM
;
1327 state
= store_get(sizeof(exim_gnutls_state_st
));
1328 store_pool
= old_pool
;
1330 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1332 DEBUG(D_tls
) debug_printf("initialising GnuTLS client session\n");
1333 rc
= gnutls_init(&state
->session
, GNUTLS_CLIENT
);
1337 state
= &state_server
;
1338 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
1340 DEBUG(D_tls
) debug_printf("initialising GnuTLS server session\n");
1341 rc
= gnutls_init(&state
->session
, GNUTLS_SERVER
);
1344 return tls_error_gnu(US
"gnutls_init", rc
, host
, errstr
);
1348 state
->tls_certificate
= certificate
;
1349 state
->tls_privatekey
= privatekey
;
1350 state
->tls_require_ciphers
= require_ciphers
;
1351 state
->tls_sni
= sni
;
1352 state
->tls_verify_certificates
= cas
;
1353 state
->tls_crl
= crl
;
1355 /* This handles the variables that might get re-expanded after TLS SNI;
1356 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1359 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1360 if ((rc
= tls_expand_session_files(state
, errstr
)) != OK
) return rc
;
1362 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1363 requires a new structure afterwards. */
1365 if ((rc
= tls_set_remaining_x509(state
, errstr
)) != OK
) return rc
;
1367 /* set SNI in client, only */
1370 if (!expand_check(sni
, US
"tls_out_sni", &state
->tlsp
->sni
, errstr
))
1372 if (state
->tlsp
->sni
&& *state
->tlsp
->sni
)
1375 debug_printf("Setting TLS client SNI to \"%s\"\n", state
->tlsp
->sni
);
1376 sz
= Ustrlen(state
->tlsp
->sni
);
1377 if ((rc
= gnutls_server_name_set(state
->session
,
1378 GNUTLS_NAME_DNS
, state
->tlsp
->sni
, sz
)))
1379 return tls_error_gnu(US
"gnutls_server_name_set", rc
, host
, errstr
);
1382 else if (state
->tls_sni
)
1383 DEBUG(D_tls
) debug_printf("*** PROBABLY A BUG *** " \
1384 "have an SNI set for a server [%s]\n", state
->tls_sni
);
1386 /* This is the priority string support,
1387 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1388 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1389 This was backwards incompatible, but means Exim no longer needs to track
1390 all algorithms and provide string forms for them. */
1393 if (state
->tls_require_ciphers
&& *state
->tls_require_ciphers
)
1395 if (!expand_check_tlsvar(tls_require_ciphers
, errstr
))
1397 if (state
->exp_tls_require_ciphers
&& *state
->exp_tls_require_ciphers
)
1399 p
= state
->exp_tls_require_ciphers
;
1400 DEBUG(D_tls
) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p
);
1405 p
= exim_default_gnutls_priority
;
1407 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p
);
1410 if ((rc
= gnutls_priority_init(&state
->priority_cache
, CCS p
, &errpos
)))
1411 return tls_error_gnu(string_sprintf(
1412 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1413 p
, errpos
- CS p
, errpos
),
1416 if ((rc
= gnutls_priority_set(state
->session
, state
->priority_cache
)))
1417 return tls_error_gnu(US
"gnutls_priority_set", rc
, host
, errstr
);
1419 /* This also sets the server ticket expiration time to the same, and
1420 the STEK rotation time to 3x. */
1422 gnutls_db_set_cache_expiration(state
->session
, ssl_session_timeout
);
1424 /* Reduce security in favour of increased compatibility, if the admin
1425 decides to make that trade-off. */
1426 if (gnutls_compat_mode
)
1428 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1429 DEBUG(D_tls
) debug_printf("lowering GnuTLS security, compatibility mode\n");
1430 gnutls_session_enable_compatibility_mode(state
->session
);
1432 DEBUG(D_tls
) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1436 *caller_state
= state
;
1442 /*************************************************
1443 * Extract peer information *
1444 *************************************************/
1446 static const uschar
*
1447 cipher_stdname_kcm(gnutls_kx_algorithm_t kx
, gnutls_cipher_algorithm_t cipher
,
1448 gnutls_mac_algorithm_t mac
)
1451 gnutls_kx_algorithm_t kx_i
;
1452 gnutls_cipher_algorithm_t cipher_i
;
1453 gnutls_mac_algorithm_t mac_i
;
1456 gnutls_cipher_suite_info(i
, cs_id
, &kx_i
, &cipher_i
, &mac_i
, NULL
);
1458 if (kx_i
== kx
&& cipher_i
== cipher
&& mac_i
== mac
)
1459 return cipher_stdname(cs_id
[0], cs_id
[1]);
1465 /* Called from both server and client code.
1466 Only this is allowed to set state->peerdn and state->have_set_peerdn
1467 and we use that to detect double-calls.
1469 NOTE: the state blocks last while the TLS connection is up, which is fine
1470 for logging in the server side, but for the client side, we log after teardown
1471 in src/deliver.c. While the session is up, we can twist about states and
1472 repoint tls_* globals, but those variables used for logging or other variable
1473 expansion that happens _after_ delivery need to have a longer life-time.
1475 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1476 doing this more than once per generation of a state context. We set them in
1477 the state context, and repoint tls_* to them. After the state goes away, the
1478 tls_* copies of the pointers remain valid and client delivery logging is happy.
1480 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1484 state exim_gnutls_state_st *
1485 errstr pointer to error string
1487 Returns: OK/DEFER/FAIL
1491 peer_status(exim_gnutls_state_st
* state
, uschar
** errstr
)
1493 gnutls_session_t session
= state
->session
;
1494 const gnutls_datum_t
* cert_list
;
1496 unsigned int cert_list_size
= 0;
1497 gnutls_protocol_t protocol
;
1498 gnutls_cipher_algorithm_t cipher
;
1499 gnutls_kx_algorithm_t kx
;
1500 gnutls_mac_algorithm_t mac
;
1501 gnutls_certificate_type_t ct
;
1502 gnutls_x509_crt_t crt
;
1506 if (state
->have_set_peerdn
)
1508 state
->have_set_peerdn
= TRUE
;
1510 state
->peerdn
= NULL
;
1513 cipher
= gnutls_cipher_get(session
);
1514 protocol
= gnutls_protocol_get_version(session
);
1515 mac
= gnutls_mac_get(session
);
1517 #ifdef GNUTLS_TLS1_3
1518 protocol
>= GNUTLS_TLS1_3
? 0 :
1520 gnutls_kx_get(session
);
1522 old_pool
= store_pool
;
1524 tls_support
* tlsp
= state
->tlsp
;
1525 store_pool
= POOL_PERM
;
1527 #ifdef SUPPORT_GNUTLS_SESS_DESC
1530 uschar
* s
= US
gnutls_session_get_desc(session
), c
;
1532 /* Nikos M suggests we use this by preference. It returns like:
1533 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
1535 For partial back-compat, put a colon after the TLS version, replace the
1536 )-( grouping with __, replace in-group - with _ and append the :keysize. */
1538 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
1540 for (s
++; (c
= *s
) && c
!= ')'; s
++) g
= string_catn(g
, s
, 1);
1541 g
= string_catn(g
, US
":", 1);
1542 if (*s
) s
++; /* now on _ between groups */
1545 for (*++s
&& ++s
; (c
= *s
) && c
!= ')'; s
++) g
= string_catn(g
, c
== '-' ? US
"_" : s
, 1);
1546 /* now on ) closing group */
1547 if ((c
= *s
) && *++s
== '-') g
= string_catn(g
, US
"__", 2);
1548 /* now on _ between groups */
1550 g
= string_catn(g
, US
":", 1);
1551 g
= string_cat(g
, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher
) * 8));
1552 state
->ciphersuite
= string_from_gstring(g
);
1555 state
->ciphersuite
= string_sprintf("%s:%s:%d",
1556 gnutls_protocol_get_name(protocol
),
1557 gnutls_cipher_suite_get_name(kx
, cipher
, mac
),
1558 (int) gnutls_cipher_get_key_size(cipher
) * 8);
1560 /* I don't see a way that spaces could occur, in the current GnuTLS
1561 code base, but it was a concern in the old code and perhaps older GnuTLS
1562 releases did return "TLS 1.0"; play it safe, just in case. */
1564 for (uschar
* p
= state
->ciphersuite
; *p
; p
++) if (isspace(*p
)) *p
= '-';
1567 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
1569 tlsp
->cipher
= state
->ciphersuite
;
1570 tlsp
->bits
= gnutls_cipher_get_key_size(cipher
) * 8;
1572 tlsp
->cipher_stdname
= cipher_stdname_kcm(kx
, cipher
, mac
);
1574 store_pool
= old_pool
;
1577 cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
);
1579 if (!cert_list
|| cert_list_size
== 0)
1581 DEBUG(D_tls
) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1582 cert_list
, cert_list_size
);
1583 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1584 return tls_error(US
"certificate verification failed",
1585 US
"no certificate received from peer", state
->host
, errstr
);
1589 if ((ct
= gnutls_certificate_type_get(session
)) != GNUTLS_CRT_X509
)
1591 const uschar
* ctn
= US
gnutls_certificate_type_get_name(ct
);
1593 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn
);
1594 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1595 return tls_error(US
"certificate verification not possible, unhandled type",
1596 ctn
, state
->host
, errstr
);
1600 #define exim_gnutls_peer_err(Label) \
1602 if (rc != GNUTLS_E_SUCCESS) \
1604 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1605 (Label), gnutls_strerror(rc)); \
1606 if (state->verify_requirement >= VERIFY_REQUIRED) \
1607 return tls_error_gnu((Label), rc, state->host, errstr); \
1612 rc
= import_cert(&cert_list
[0], &crt
);
1613 exim_gnutls_peer_err(US
"cert 0");
1615 state
->tlsp
->peercert
= state
->peercert
= crt
;
1618 rc
= gnutls_x509_crt_get_dn(crt
, NULL
, &sz
);
1619 if (rc
!= GNUTLS_E_SHORT_MEMORY_BUFFER
)
1621 exim_gnutls_peer_err(US
"getting size for cert DN failed");
1622 return FAIL
; /* should not happen */
1624 dn_buf
= store_get_perm(sz
);
1625 rc
= gnutls_x509_crt_get_dn(crt
, CS dn_buf
, &sz
);
1626 exim_gnutls_peer_err(US
"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1628 state
->peerdn
= dn_buf
;
1631 #undef exim_gnutls_peer_err
1637 /*************************************************
1638 * Verify peer certificate *
1639 *************************************************/
1641 /* Called from both server and client code.
1642 *Should* be using a callback registered with
1643 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1644 the peer information, but that's too new for some OSes.
1647 state exim_gnutls_state_st *
1648 errstr where to put an error message
1651 FALSE if the session should be rejected
1652 TRUE if the cert is okay or we just don't care
1656 verify_certificate(exim_gnutls_state_st
* state
, uschar
** errstr
)
1661 DEBUG(D_tls
) debug_printf("TLS: checking peer certificate\n");
1663 rc
= peer_status(state
, errstr
);
1665 if (state
->verify_requirement
== VERIFY_NONE
)
1668 if (rc
!= OK
|| !state
->peerdn
)
1670 verify
= GNUTLS_CERT_INVALID
;
1671 *errstr
= US
"certificate not supplied";
1677 if (state
->verify_requirement
== VERIFY_DANE
&& state
->host
)
1679 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1680 including talking to a DNS resolver. But we want to do that bit ourselves
1681 as the testsuite intercepts and fakes its own DNS environment. */
1686 const gnutls_datum_t
* certlist
=
1687 gnutls_certificate_get_peers(state
->session
, &lsize
);
1688 int usage
= tls_out
.tlsa_usage
;
1690 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1691 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1692 dane-verification separately so that we know which selector verified;
1693 then we know whether to do name-verification (needed for TA but not EE). */
1695 if (usage
== ((1<<DANESSL_USAGE_DANE_TA
) | (1<<DANESSL_USAGE_DANE_EE
)))
1696 { /* a mixed-usage bundle */
1701 for(nrec
= 0; state
->dane_data_len
[nrec
]; ) nrec
++;
1704 dd
= store_get(nrec
* sizeof(uschar
*));
1705 ddl
= store_get(nrec
* sizeof(int));
1708 if ((rc
= dane_state_init(&s
, 0)))
1711 for (usage
= DANESSL_USAGE_DANE_EE
;
1712 usage
>= DANESSL_USAGE_DANE_TA
; usage
--)
1713 { /* take records with this usage */
1714 for (j
= i
= 0; i
< nrec
; i
++)
1715 if (state
->dane_data
[i
][0] == usage
)
1717 dd
[j
] = state
->dane_data
[i
];
1718 ddl
[j
++] = state
->dane_data_len
[i
];
1725 if ((rc
= dane_raw_tlsa(s
, &r
, (char * const *)dd
, ddl
, 1, 0)))
1728 if ((rc
= dane_verify_crt_raw(s
, certlist
, lsize
,
1729 gnutls_certificate_type_get(state
->session
),
1731 usage
== DANESSL_USAGE_DANE_EE
1732 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE
: 0,
1736 debug_printf("TLSA record problem: %s\n", dane_strerror(rc
));
1738 else if (verify
== 0) /* verification passed */
1746 if (rc
) goto tlsa_prob
;
1751 if ( (rc
= dane_state_init(&s
, 0))
1752 || (rc
= dane_raw_tlsa(s
, &r
, state
->dane_data
, state
->dane_data_len
,
1754 || (rc
= dane_verify_crt_raw(s
, certlist
, lsize
,
1755 gnutls_certificate_type_get(state
->session
),
1757 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1758 usage
== (1 << DANESSL_USAGE_DANE_EE
)
1759 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE
: 0,
1768 if (verify
!= 0) /* verification failed */
1771 (void) dane_verification_status_print(verify
, &str
, 0);
1772 *errstr
= US str
.data
; /* don't bother to free */
1776 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1777 /* If a TA-mode TLSA record was used for verification we must additionally
1778 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1780 if (usage
& (1 << DANESSL_USAGE_DANE_EE
))
1783 state
->peer_dane_verified
= state
->peer_cert_verified
= TRUE
;
1786 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1787 /* Assume that the name on the A-record is the one that should be matching
1788 the cert. An alternate view is that the domain part of the email address
1789 is also permissible. */
1791 if (gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
,
1792 CS state
->host
->name
))
1794 state
->peer_dane_verified
= state
->peer_cert_verified
= TRUE
;
1799 #endif /*SUPPORT_DANE*/
1801 rc
= gnutls_certificate_verify_peers2(state
->session
, &verify
);
1804 /* Handle the result of verification. INVALID is set if any others are. */
1806 if (rc
< 0 || verify
& (GNUTLS_CERT_INVALID
|GNUTLS_CERT_REVOKED
))
1808 state
->peer_cert_verified
= FALSE
;
1811 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
1816 if (gnutls_certificate_verification_status_print(verify
,
1817 gnutls_certificate_type_get(state
->session
), &txt
, 0)
1818 == GNUTLS_E_SUCCESS
)
1820 debug_printf("%s\n", txt
.data
);
1821 gnutls_free(txt
.data
);
1825 *errstr
= verify
& GNUTLS_CERT_REVOKED
1826 ? US
"certificate revoked" : US
"certificate invalid";
1830 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
1831 *errstr
, state
->peerdn
? state
->peerdn
: US
"<unset>");
1833 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1836 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
1841 /* Client side, check the server's certificate name versus the name on the
1842 A-record for the connection we made. What to do for server side - what name
1843 to use for client? We document that there is no such checking for server
1846 if ( state
->exp_tls_verify_cert_hostnames
1847 && !gnutls_x509_crt_check_hostname(state
->tlsp
->peercert
,
1848 CS state
->exp_tls_verify_cert_hostnames
)
1852 debug_printf("TLS certificate verification failed: cert name mismatch\n");
1853 if (state
->verify_requirement
>= VERIFY_REQUIRED
)
1858 state
->peer_cert_verified
= TRUE
;
1859 DEBUG(D_tls
) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
1860 state
->peerdn
? state
->peerdn
: US
"<unset>");
1864 state
->tlsp
->peerdn
= state
->peerdn
;
1869 *errstr
= string_sprintf("TLSA record problem: %s",
1870 rc
== DANE_E_REQUESTED_DATA_NOT_AVAILABLE
? "none usable" : dane_strerror(rc
));
1874 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_BAD_CERTIFICATE
);
1881 /* ------------------------------------------------------------------------ */
1884 /* Logging function which can be registered with
1885 * gnutls_global_set_log_function()
1886 * gnutls_global_set_log_level() 0..9
1888 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1890 exim_gnutls_logger_cb(int level
, const char *message
)
1892 size_t len
= strlen(message
);
1895 DEBUG(D_tls
) debug_printf("GnuTLS<%d> empty debug message\n", level
);
1898 DEBUG(D_tls
) debug_printf("GnuTLS<%d>: %s%s", level
, message
,
1899 message
[len
-1] == '\n' ? "" : "\n");
1904 /* Called after client hello, should handle SNI work.
1905 This will always set tls_sni (state->received_sni) if available,
1906 and may trigger presenting different certificates,
1907 if state->trigger_sni_changes is TRUE.
1909 Should be registered with
1910 gnutls_handshake_set_post_client_hello_function()
1912 "This callback must return 0 on success or a gnutls error code to terminate the
1915 For inability to get SNI information, we return 0.
1916 We only return non-zero if re-setup failed.
1917 Only used for server-side TLS.
1921 exim_sni_handling_cb(gnutls_session_t session
)
1923 char sni_name
[MAX_HOST_LEN
];
1924 size_t data_len
= MAX_HOST_LEN
;
1925 exim_gnutls_state_st
*state
= &state_server
;
1926 unsigned int sni_type
;
1928 uschar
* dummy_errstr
;
1930 rc
= gnutls_server_name_get(session
, sni_name
, &data_len
, &sni_type
, 0);
1931 if (rc
!= GNUTLS_E_SUCCESS
)
1934 if (rc
== GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
)
1935 debug_printf("TLS: no SNI presented in handshake.\n");
1937 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
1938 gnutls_strerror(rc
), rc
);
1943 if (sni_type
!= GNUTLS_NAME_DNS
)
1945 DEBUG(D_tls
) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type
);
1949 /* We now have a UTF-8 string in sni_name */
1950 old_pool
= store_pool
;
1951 store_pool
= POOL_PERM
;
1952 state
->received_sni
= string_copyn(US sni_name
, data_len
);
1953 store_pool
= old_pool
;
1955 /* We set this one now so that variable expansions below will work */
1956 state
->tlsp
->sni
= state
->received_sni
;
1958 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name
,
1959 state
->trigger_sni_changes
? "" : " (unused for certificate selection)");
1961 if (!state
->trigger_sni_changes
)
1964 if ((rc
= tls_expand_session_files(state
, &dummy_errstr
)) != OK
)
1966 /* If the setup of certs/etc failed before handshake, TLS would not have
1967 been offered. The best we can do now is abort. */
1968 return GNUTLS_E_APPLICATION_ERROR_MIN
;
1971 rc
= tls_set_remaining_x509(state
, &dummy_errstr
);
1972 if (rc
!= OK
) return GNUTLS_E_APPLICATION_ERROR_MIN
;
1979 #ifndef DISABLE_OCSP
1982 server_ocsp_stapling_cb(gnutls_session_t session
, void * ptr
,
1983 gnutls_datum_t
* ocsp_response
)
1986 DEBUG(D_tls
) debug_printf("OCSP stapling callback: %s\n", US ptr
);
1988 if ((ret
= gnutls_load_file(ptr
, ocsp_response
)) < 0)
1990 DEBUG(D_tls
) debug_printf("Failed to load ocsp stapling file %s\n",
1992 tls_in
.ocsp
= OCSP_NOT_RESP
;
1993 return GNUTLS_E_NO_CERTIFICATE_STATUS
;
1996 tls_in
.ocsp
= OCSP_VFY_NOT_TRIED
;
2003 #ifndef DISABLE_EVENT
2005 We use this callback to get observability and detail-level control
2006 for an exim TLS connection (either direction), raising a tls:cert event
2007 for each cert in the chain presented by the peer. Any event
2008 can deny verification.
2010 Return 0 for the handshake to continue or non-zero to terminate.
2014 verify_cb(gnutls_session_t session
)
2016 const gnutls_datum_t
* cert_list
;
2017 unsigned int cert_list_size
= 0;
2018 gnutls_x509_crt_t crt
;
2021 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(session
);
2023 if ((cert_list
= gnutls_certificate_get_peers(session
, &cert_list_size
)))
2024 while (cert_list_size
--)
2026 if ((rc
= import_cert(&cert_list
[cert_list_size
], &crt
)) != GNUTLS_E_SUCCESS
)
2028 DEBUG(D_tls
) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2029 cert_list_size
, gnutls_strerror(rc
));
2033 state
->tlsp
->peercert
= crt
;
2034 if ((yield
= event_raise(state
->event_action
,
2035 US
"tls:cert", string_sprintf("%d", cert_list_size
))))
2037 log_write(0, LOG_MAIN
,
2038 "SSL verify denied by event-action: depth=%d: %s",
2039 cert_list_size
, yield
);
2040 return 1; /* reject */
2042 state
->tlsp
->peercert
= NULL
;
2052 ddump(gnutls_datum_t
* d
)
2054 gstring
* g
= string_get((d
->size
+1) * 2);
2055 uschar
* s
= d
->data
;
2056 for (unsigned i
= d
->size
; i
> 0; i
--, s
++)
2058 g
= string_catn(g
, US
"0123456789abcdef" + (*s
>> 4), 1);
2059 g
= string_catn(g
, US
"0123456789abcdef" + (*s
& 0xf), 1);
2065 post_handshake_debug(exim_gnutls_state_st
* state
)
2067 #ifdef SUPPORT_GNUTLS_SESS_DESC
2068 debug_printf("%s\n", gnutls_session_get_desc(state
->session
));
2070 #ifdef SUPPORT_GNUTLS_KEYLOG
2071 # ifdef GNUTLS_TLS1_3
2072 if (gnutls_protocol_get_version(state
->session
) < GNUTLS_TLS1_3
)
2077 gnutls_datum_t c
, s
;
2079 /* we only want the client random and the master secret */
2080 gnutls_session_get_random(state
->session
, &c
, &s
);
2081 gnutls_session_get_master_secret(state
->session
, &s
);
2084 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc
->ptr
, gc
->s
, (int)gs
->ptr
, gs
->s
);
2087 debug_printf("To get keying info for TLS1.3 is hard:\n"
2088 " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
2089 " add SSLKEYLOGFILE to keep_environment in the exim config\n"
2090 " run exim as root\n"
2091 " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n");
2096 #ifdef EXPERIMENTAL_TLS_RESUME
2098 tls_server_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
2099 unsigned incoming
, const gnutls_datum_t
* msg
)
2101 DEBUG(D_tls
) debug_printf("newticket cb\n");
2102 tls_in
.resumption
|= RESUME_CLIENT_REQUESTED
;
2107 tls_server_resume_prehandshake(exim_gnutls_state_st
* state
)
2109 /* Should the server offer session resumption? */
2110 tls_in
.resumption
= RESUME_SUPPORTED
;
2111 if (verify_check_host(&tls_resumption_hosts
) == OK
)
2114 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2115 an offered resumption is unacceptable. We lose one resumption per ticket
2116 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2117 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2118 least they go out in a single packet. */
2120 if (!(rc
= gnutls_session_ticket_enable_server(state
->session
,
2121 &server_sessticket_key
)))
2122 tls_in
.resumption
|= RESUME_SERVER_TICKET
;
2125 debug_printf("enabling session tickets: %s\n", US
gnutls_strerror(rc
));
2127 /* Try to tell if we see a ticket request */
2128 gnutls_handshake_set_hook_function(state
->session
,
2129 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
, GNUTLS_HOOK_POST
, tls_server_ticket_cb
);
2134 tls_server_resume_posthandshake(exim_gnutls_state_st
* state
)
2136 if (gnutls_session_resumption_requested(state
->session
))
2138 /* This tells us the client sent a full ticket. We use a
2139 callback on session-ticket request, elsewhere, to tell
2140 if a client asked for a ticket. */
2142 tls_in
.resumption
|= RESUME_CLIENT_SUGGESTED
;
2143 DEBUG(D_tls
) debug_printf("client requested resumption\n");
2145 if (gnutls_session_is_resumed(state
->session
))
2147 tls_in
.resumption
|= RESUME_USED
;
2148 DEBUG(D_tls
) debug_printf("Session resumed\n");
2152 /* ------------------------------------------------------------------------ */
2153 /* Exported functions */
2158 /*************************************************
2159 * Start a TLS session in a server *
2160 *************************************************/
2162 /* This is called when Exim is running as a server, after having received
2163 the STARTTLS command. It must respond to that command, and then negotiate
2167 require_ciphers list of allowed ciphers or NULL
2168 errstr pointer to error string
2170 Returns: OK on success
2171 DEFER for errors before the start of the negotiation
2172 FAIL for errors during the negotiation; the server can't
2177 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
2180 exim_gnutls_state_st
* state
= NULL
;
2182 /* Check for previous activation */
2183 if (tls_in
.active
.sock
>= 0)
2185 tls_error(US
"STARTTLS received after TLS started", US
"", NULL
, errstr
);
2186 smtp_printf("554 Already in TLS\r\n", FALSE
);
2190 /* Initialize the library. If it fails, it will already have logged the error
2191 and sent an SMTP response. */
2193 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a server\n");
2195 if ((rc
= tls_init(NULL
, tls_certificate
, tls_privatekey
,
2196 NULL
, tls_verify_certificates
, tls_crl
,
2197 require_ciphers
, &state
, &tls_in
, errstr
)) != OK
) return rc
;
2199 #ifdef EXPERIMENTAL_TLS_RESUME
2200 tls_server_resume_prehandshake(state
);
2203 /* If this is a host for which certificate verification is mandatory or
2204 optional, set up appropriately. */
2206 if (verify_check_host(&tls_verify_hosts
) == OK
)
2209 debug_printf("TLS: a client certificate will be required.\n");
2210 state
->verify_requirement
= VERIFY_REQUIRED
;
2211 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2213 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
2216 debug_printf("TLS: a client certificate will be requested but not required.\n");
2217 state
->verify_requirement
= VERIFY_OPTIONAL
;
2218 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2223 debug_printf("TLS: a client certificate will not be requested.\n");
2224 state
->verify_requirement
= VERIFY_NONE
;
2225 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2228 #ifndef DISABLE_EVENT
2231 state
->event_action
= event_action
;
2232 gnutls_session_set_ptr(state
->session
, state
);
2233 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2237 /* Register SNI handling; always, even if not in tls_certificate, so that the
2238 expansion variable $tls_sni is always available. */
2240 gnutls_handshake_set_post_client_hello_function(state
->session
,
2241 exim_sni_handling_cb
);
2243 /* Set context and tell client to go ahead, except in the case of TLS startup
2244 on connection, where outputting anything now upsets the clients and tends to
2245 make them disconnect. We need to have an explicit fflush() here, to force out
2246 the response. Other smtp_printf() calls do not need it, because in non-TLS
2247 mode, the fflush() happens when smtp_getc() is called. */
2249 if (!state
->tlsp
->on_connect
)
2251 smtp_printf("220 TLS go ahead\r\n", FALSE
);
2255 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2256 that the GnuTLS library doesn't.
2257 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2258 to set (and clear down afterwards) up a pull-timeout callback function that does
2259 a select, so we're no better off unless avoiding signals becomes an issue. */
2261 gnutls_transport_set_ptr2(state
->session
,
2262 (gnutls_transport_ptr_t
)(long) fileno(smtp_in
),
2263 (gnutls_transport_ptr_t
)(long) fileno(smtp_out
));
2264 state
->fd_in
= fileno(smtp_in
);
2265 state
->fd_out
= fileno(smtp_out
);
2267 sigalrm_seen
= FALSE
;
2268 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2270 rc
= gnutls_handshake(state
->session
);
2271 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
2274 if (rc
!= GNUTLS_E_SUCCESS
)
2276 /* It seems that, except in the case of a timeout, we have to close the
2277 connection right here; otherwise if the other end is running OpenSSL it hangs
2278 until the server times out. */
2282 tls_error(US
"gnutls_handshake", US
"timed out", NULL
, errstr
);
2283 gnutls_db_remove_session(state
->session
);
2287 tls_error_gnu(US
"gnutls_handshake", rc
, NULL
, errstr
);
2288 (void) gnutls_alert_send_appropriate(state
->session
, rc
);
2289 gnutls_deinit(state
->session
);
2290 gnutls_certificate_free_credentials(state
->x509_cred
);
2292 shutdown(state
->fd_out
, SHUT_WR
);
2293 for (int i
= 1024; fgetc(smtp_in
) != EOF
&& i
> 0; ) i
--; /* drain skt */
2294 (void)fclose(smtp_out
);
2295 (void)fclose(smtp_in
);
2296 smtp_out
= smtp_in
= NULL
;
2302 #ifdef EXPERIMENTAL_TLS_RESUME
2303 tls_server_resume_posthandshake(state
);
2306 DEBUG(D_tls
) post_handshake_debug(state
);
2308 /* Verify after the fact */
2310 if (!verify_certificate(state
, errstr
))
2312 if (state
->verify_requirement
!= VERIFY_OPTIONAL
)
2314 (void) tls_error(US
"certificate verification failed", *errstr
, NULL
, errstr
);
2318 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2322 /* Sets various Exim expansion variables; always safe within server */
2324 extract_exim_vars_from_tls_state(state
);
2326 /* TLS has been set up. Adjust the input functions to read via TLS,
2327 and initialize appropriately. */
2329 state
->xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2331 receive_getc
= tls_getc
;
2332 receive_getbuf
= tls_getbuf
;
2333 receive_get_cache
= tls_get_cache
;
2334 receive_ungetc
= tls_ungetc
;
2335 receive_feof
= tls_feof
;
2336 receive_ferror
= tls_ferror
;
2337 receive_smtp_buffered
= tls_smtp_buffered
;
2346 tls_client_setup_hostname_checks(host_item
* host
, exim_gnutls_state_st
* state
,
2347 smtp_transport_options_block
* ob
)
2349 if (verify_check_given_host(CUSS
&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2351 state
->exp_tls_verify_cert_hostnames
=
2353 string_domain_utf8_to_alabel(host
->name
, NULL
);
2358 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2359 state
->exp_tls_verify_cert_hostnames
);
2367 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2368 GnuTLS-DANE's preferred format. Hang it on the state str for later
2369 use in DANE verification.
2371 We point at the dnsa data not copy it, so it must remain valid until
2372 after verification is done.*/
2375 dane_tlsa_load(exim_gnutls_state_st
* state
, dns_answer
* dnsa
)
2379 const char ** dane_data
;
2380 int * dane_data_len
;
2383 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2384 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2385 ) if (rr
->type
== T_TLSA
) i
++;
2387 dane_data
= store_get(i
* sizeof(uschar
*));
2388 dane_data_len
= store_get(i
* sizeof(int));
2391 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2392 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2393 ) if (rr
->type
== T_TLSA
&& rr
->size
> 3)
2395 const uschar
* p
= rr
->data
;
2396 uint8_t usage
= p
[0], sel
= p
[1], type
= p
[2];
2399 debug_printf("TLSA: %d %d %d size %d\n", usage
, sel
, type
, rr
->size
);
2401 if ( (usage
!= DANESSL_USAGE_DANE_TA
&& usage
!= DANESSL_USAGE_DANE_EE
)
2402 || (sel
!= 0 && sel
!= 1)
2407 case 0: /* Full: cannot check at present */
2409 case 1: if (rr
->size
!= 3 + 256/8) continue; /* sha2-256 */
2411 case 2: if (rr
->size
!= 3 + 512/8) continue; /* sha2-512 */
2416 tls_out
.tlsa_usage
|= 1<<usage
;
2417 dane_data
[i
] = CS p
;
2418 dane_data_len
[i
++] = rr
->size
;
2421 if (!i
) return FALSE
;
2423 dane_data
[i
] = NULL
;
2424 dane_data_len
[i
] = 0;
2426 state
->dane_data
= (char * const *)dane_data
;
2427 state
->dane_data_len
= dane_data_len
;
2434 #ifdef EXPERIMENTAL_TLS_RESUME
2435 /* On the client, get any stashed session for the given IP from hints db
2436 and apply it to the ssl-connection for attempted resumption. Although
2437 there is a gnutls_session_ticket_enable_client() interface it is
2438 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
2439 by deafult". There seems to be no way to disable them, so even hosts not
2440 enabled by the transport option will be sent a ticket request. We will
2441 however avoid storing and retrieving session information. */
2444 tls_retrieve_session(tls_support
* tlsp
, gnutls_session_t session
,
2445 host_item
* host
, smtp_transport_options_block
* ob
)
2447 tlsp
->resumption
= RESUME_SUPPORTED
;
2448 if (verify_check_given_host(CUSS
&ob
->tls_resumption_hosts
, host
) == OK
)
2450 dbdata_tls_session
* dt
;
2452 open_db dbblock
, * dbm_file
;
2455 debug_printf("check for resumable session for %s\n", host
->address
);
2456 tlsp
->host_resumable
= TRUE
;
2457 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
2458 if ((dbm_file
= dbfn_open(US
"tls", O_RDONLY
, &dbblock
, FALSE
, FALSE
)))
2460 /* key for the db is the IP */
2461 if ((dt
= dbfn_read_with_length(dbm_file
, host
->address
, &len
)))
2462 if (!(rc
= gnutls_session_set_data(session
,
2463 CUS dt
->session
, (size_t)len
- sizeof(dbdata_tls_session
))))
2465 DEBUG(D_tls
) debug_printf("good session\n");
2466 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
2468 else DEBUG(D_tls
) debug_printf("setting session resumption data: %s\n",
2469 US
gnutls_strerror(rc
));
2470 dbfn_close(dbm_file
);
2477 tls_save_session(tls_support
* tlsp
, gnutls_session_t session
, const host_item
* host
)
2479 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
2480 but this flag is not set until the second. TLS 1.3 it's the other way about.
2481 Keep both calls as the session data cannot be extracted before handshake
2484 if (gnutls_session_get_flags(session
) & GNUTLS_SFLAGS_SESSION_TICKET
)
2489 DEBUG(D_tls
) debug_printf("server offered session ticket\n");
2490 tlsp
->ticket_received
= TRUE
;
2491 tlsp
->resumption
|= RESUME_SERVER_TICKET
;
2493 if (tlsp
->host_resumable
)
2494 if (!(rc
= gnutls_session_get_data2(session
, &tkt
)))
2496 open_db dbblock
, * dbm_file
;
2497 int dlen
= sizeof(dbdata_tls_session
) + tkt
.size
;
2498 dbdata_tls_session
* dt
= store_get(dlen
);
2500 DEBUG(D_tls
) debug_printf("session data size %u\n", (unsigned)tkt
.size
);
2501 memcpy(dt
->session
, tkt
.data
, tkt
.size
);
2502 gnutls_free(tkt
.data
);
2504 if ((dbm_file
= dbfn_open(US
"tls", O_RDWR
, &dbblock
, FALSE
, FALSE
)))
2506 /* key for the db is the IP */
2507 dbfn_delete(dbm_file
, host
->address
);
2508 dbfn_write(dbm_file
, host
->address
, dt
, dlen
);
2509 dbfn_close(dbm_file
);
2512 debug_printf("wrote session db (len %u)\n", (unsigned)dlen
);
2516 debug_printf("extract session data: %s\n", US
gnutls_strerror(rc
));
2521 /* With a TLS1.3 session, the ticket(s) are not seen until
2522 the first data read is attempted. And there's often two of them.
2523 Pick them up with this callback. We are also called for 1.2
2527 tls_client_ticket_cb(gnutls_session_t sess
, u_int htype
, unsigned when
,
2528 unsigned incoming
, const gnutls_datum_t
* msg
)
2530 exim_gnutls_state_st
* state
= gnutls_session_get_ptr(sess
);
2531 tls_support
* tlsp
= state
->tlsp
;
2533 DEBUG(D_tls
) debug_printf("newticket cb\n");
2535 if (!tlsp
->ticket_received
)
2536 tls_save_session(tlsp
, sess
, state
->host
);
2542 tls_client_resume_prehandshake(exim_gnutls_state_st
* state
,
2543 tls_support
* tlsp
, host_item
* host
,
2544 smtp_transport_options_block
* ob
)
2546 gnutls_session_set_ptr(state
->session
, state
);
2547 gnutls_handshake_set_hook_function(state
->session
,
2548 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
, GNUTLS_HOOK_POST
, tls_client_ticket_cb
);
2550 tls_retrieve_session(tlsp
, state
->session
, host
, ob
);
2554 tls_client_resume_posthandshake(exim_gnutls_state_st
* state
,
2555 tls_support
* tlsp
, host_item
* host
)
2557 if (gnutls_session_is_resumed(state
->session
))
2559 DEBUG(D_tls
) debug_printf("Session resumed\n");
2560 tlsp
->resumption
|= RESUME_USED
;
2563 tls_save_session(tlsp
, state
->session
, host
);
2565 #endif /* EXPERIMENTAL_TLS_RESUME */
2568 /*************************************************
2569 * Start a TLS session in a client *
2570 *************************************************/
2572 /* Called from the smtp transport after STARTTLS has been accepted.
2575 cctx connection context
2576 conn_args connection details
2577 cookie datum for randomness (not used)
2578 tlsp record details of channel configuration here; must be non-NULL
2579 errstr error string pointer
2581 Returns: TRUE for success with TLS session context set in smtp context,
2586 tls_client_start(client_conn_ctx
* cctx
, smtp_connect_args
* conn_args
,
2587 void * cookie ARG_UNUSED
,
2588 tls_support
* tlsp
, uschar
** errstr
)
2590 host_item
* host
= conn_args
->host
; /* for msgs and option-tests */
2591 transport_instance
* tb
= conn_args
->tblock
; /* always smtp or NULL */
2592 smtp_transport_options_block
* ob
= tb
2593 ? (smtp_transport_options_block
*)tb
->options_block
2594 : &smtp_transport_option_defaults
;
2596 exim_gnutls_state_st
* state
= NULL
;
2597 uschar
* cipher_list
= NULL
;
2599 #ifndef DISABLE_OCSP
2601 verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
;
2602 BOOL request_ocsp
= require_ocsp
? TRUE
2603 : verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2606 DEBUG(D_tls
) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx
->sock
);
2609 /* If dane is flagged, have either request or require dane for this host, and
2610 a TLSA record found. Therefore, dane verify required. Which implies cert must
2611 be requested and supplied, dane verify must pass, and cert verify irrelevant
2612 (incl. hostnames), and (caller handled) require_tls */
2614 if (conn_args
->dane
&& ob
->dane_require_tls_ciphers
)
2616 /* not using expand_check_tlsvar because not yet in state */
2617 if (!expand_check(ob
->dane_require_tls_ciphers
, US
"dane_require_tls_ciphers",
2618 &cipher_list
, errstr
))
2620 cipher_list
= cipher_list
&& *cipher_list
2621 ? ob
->dane_require_tls_ciphers
: ob
->tls_require_ciphers
;
2626 cipher_list
= ob
->tls_require_ciphers
;
2628 if (tls_init(host
, ob
->tls_certificate
, ob
->tls_privatekey
,
2629 ob
->tls_sni
, ob
->tls_verify_certificates
, ob
->tls_crl
,
2630 cipher_list
, &state
, tlsp
, errstr
) != OK
)
2634 int dh_min_bits
= ob
->tls_dh_min_bits
;
2635 if (dh_min_bits
< EXIM_CLIENT_DH_MIN_MIN_BITS
)
2638 debug_printf("WARNING: tls_dh_min_bits far too low,"
2639 " clamping %d up to %d\n",
2640 dh_min_bits
, EXIM_CLIENT_DH_MIN_MIN_BITS
);
2641 dh_min_bits
= EXIM_CLIENT_DH_MIN_MIN_BITS
;
2644 DEBUG(D_tls
) debug_printf("Setting D-H prime minimum"
2645 " acceptable bits to %d\n",
2647 gnutls_dh_set_prime_bits(state
->session
, dh_min_bits
);
2650 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2651 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2652 the specified host patterns if one of them is defined */
2655 if (conn_args
->dane
&& dane_tlsa_load(state
, &conn_args
->tlsa_dnsa
))
2658 debug_printf("TLS: server certificate DANE required.\n");
2659 state
->verify_requirement
= VERIFY_DANE
;
2660 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2664 if ( ( state
->exp_tls_verify_certificates
2665 && !ob
->tls_verify_hosts
2666 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2668 || verify_check_given_host(CUSS
&ob
->tls_verify_hosts
, host
) == OK
2671 tls_client_setup_hostname_checks(host
, state
, ob
);
2673 debug_printf("TLS: server certificate verification required.\n");
2674 state
->verify_requirement
= VERIFY_REQUIRED
;
2675 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUIRE
);
2677 else if (verify_check_given_host(CUSS
&ob
->tls_try_verify_hosts
, host
) == OK
)
2679 tls_client_setup_hostname_checks(host
, state
, ob
);
2681 debug_printf("TLS: server certificate verification optional.\n");
2682 state
->verify_requirement
= VERIFY_OPTIONAL
;
2683 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_REQUEST
);
2688 debug_printf("TLS: server certificate verification not required.\n");
2689 state
->verify_requirement
= VERIFY_NONE
;
2690 gnutls_certificate_server_set_request(state
->session
, GNUTLS_CERT_IGNORE
);
2693 #ifndef DISABLE_OCSP
2694 /* supported since GnuTLS 3.1.3 */
2697 DEBUG(D_tls
) debug_printf("TLS: will request OCSP stapling\n");
2698 if ((rc
= gnutls_ocsp_status_request_enable_client(state
->session
,
2699 NULL
, 0, NULL
)) != OK
)
2701 tls_error_gnu(US
"cert-status-req", rc
, state
->host
, errstr
);
2704 tlsp
->ocsp
= OCSP_NOT_RESP
;
2708 #ifdef EXPERIMENTAL_TLS_RESUME
2709 tls_client_resume_prehandshake(state
, tlsp
, host
, ob
);
2712 #ifndef DISABLE_EVENT
2713 if (tb
&& tb
->event_action
)
2715 state
->event_action
= tb
->event_action
;
2716 gnutls_session_set_ptr(state
->session
, state
);
2717 gnutls_certificate_set_verify_function(state
->x509_cred
, verify_cb
);
2721 gnutls_transport_set_ptr(state
->session
, (gnutls_transport_ptr_t
)(long) cctx
->sock
);
2722 state
->fd_in
= cctx
->sock
;
2723 state
->fd_out
= cctx
->sock
;
2725 DEBUG(D_tls
) debug_printf("about to gnutls_handshake\n");
2726 /* There doesn't seem to be a built-in timeout on connection. */
2728 sigalrm_seen
= FALSE
;
2729 ALARM(ob
->command_timeout
);
2731 rc
= gnutls_handshake(state
->session
);
2732 while (rc
== GNUTLS_E_AGAIN
|| rc
== GNUTLS_E_INTERRUPTED
&& !sigalrm_seen
);
2735 if (rc
!= GNUTLS_E_SUCCESS
)
2739 gnutls_alert_send(state
->session
, GNUTLS_AL_FATAL
, GNUTLS_A_USER_CANCELED
);
2740 tls_error(US
"gnutls_handshake", US
"timed out", state
->host
, errstr
);
2743 tls_error_gnu(US
"gnutls_handshake", rc
, state
->host
, errstr
);
2747 DEBUG(D_tls
) post_handshake_debug(state
);
2751 if (!verify_certificate(state
, errstr
))
2753 tls_error(US
"certificate verification failed", *errstr
, state
->host
, errstr
);
2757 #ifndef DISABLE_OCSP
2762 gnutls_datum_t stapling
;
2763 gnutls_ocsp_resp_t resp
;
2764 gnutls_datum_t printed
;
2765 if ( (rc
= gnutls_ocsp_status_request_get(state
->session
, &stapling
)) == 0
2766 && (rc
= gnutls_ocsp_resp_init(&resp
)) == 0
2767 && (rc
= gnutls_ocsp_resp_import(resp
, &stapling
)) == 0
2768 && (rc
= gnutls_ocsp_resp_print(resp
, GNUTLS_OCSP_PRINT_FULL
, &printed
)) == 0
2771 debug_printf("%.4096s", printed
.data
);
2772 gnutls_free(printed
.data
);
2775 (void) tls_error_gnu(US
"ocsp decode", rc
, state
->host
, errstr
);
2778 if (gnutls_ocsp_status_request_is_checked(state
->session
, 0) == 0)
2780 tlsp
->ocsp
= OCSP_FAILED
;
2781 tls_error(US
"certificate status check failed", NULL
, state
->host
, errstr
);
2784 DEBUG(D_tls
) debug_printf("Passed OCSP checking\n");
2785 tlsp
->ocsp
= OCSP_VFIED
;
2789 #ifdef EXPERIMENTAL_TLS_RESUME
2790 tls_client_resume_posthandshake(state
, tlsp
, host
);
2793 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2795 extract_exim_vars_from_tls_state(state
);
2797 cctx
->tls_ctx
= state
;
2804 /*************************************************
2805 * Close down a TLS session *
2806 *************************************************/
2808 /* This is also called from within a delivery subprocess forked from the
2809 daemon, to shut down the TLS library, without actually doing a shutdown (which
2810 would tamper with the TLS session in the parent process).
2813 ct_ctx client context pointer, or NULL for the one global server context
2814 shutdown 1 if TLS close-alert is to be sent,
2815 2 if also response to be waited for
2821 tls_close(void * ct_ctx
, int shutdown
)
2823 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
2825 if (!state
->tlsp
|| state
->tlsp
->active
.sock
< 0) return; /* TLS was not active */
2829 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS%s\n",
2830 shutdown
> 1 ? " (with response-wait)" : "");
2833 gnutls_bye(state
->session
, shutdown
> 1 ? GNUTLS_SHUT_RDWR
: GNUTLS_SHUT_WR
);
2837 gnutls_deinit(state
->session
);
2838 gnutls_certificate_free_credentials(state
->x509_cred
);
2841 state
->tlsp
->active
.sock
= -1;
2842 state
->tlsp
->active
.tls_ctx
= NULL
;
2843 if (state
->xfer_buffer
) store_free(state
->xfer_buffer
);
2844 memcpy(state
, &exim_gnutls_state_init
, sizeof(exim_gnutls_state_init
));
2851 tls_refill(unsigned lim
)
2853 exim_gnutls_state_st
* state
= &state_server
;
2856 DEBUG(D_tls
) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
2857 state
->session
, state
->xfer_buffer
, ssl_xfer_buffer_size
);
2859 sigalrm_seen
= FALSE
;
2860 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2863 inbytes
= gnutls_record_recv(state
->session
, state
->xfer_buffer
,
2864 MIN(ssl_xfer_buffer_size
, lim
));
2865 while (inbytes
== GNUTLS_E_AGAIN
);
2867 if (smtp_receive_timeout
> 0) ALARM_CLR(0);
2869 if (had_command_timeout
) /* set by signal handler */
2870 smtp_command_timeout_exit(); /* does not return */
2871 if (had_command_sigterm
)
2872 smtp_command_sigterm_exit();
2873 if (had_data_timeout
)
2874 smtp_data_timeout_exit();
2875 if (had_data_sigint
)
2876 smtp_data_sigint_exit();
2878 /* Timeouts do not get this far. A zero-byte return appears to mean that the
2879 TLS session has been closed down, not that the socket itself has been closed
2880 down. Revert to non-TLS handling. */
2884 DEBUG(D_tls
) debug_printf("Got tls read timeout\n");
2885 state
->xfer_error
= TRUE
;
2889 else if (inbytes
== 0)
2891 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
2893 receive_getc
= smtp_getc
;
2894 receive_getbuf
= smtp_getbuf
;
2895 receive_get_cache
= smtp_get_cache
;
2896 receive_ungetc
= smtp_ungetc
;
2897 receive_feof
= smtp_feof
;
2898 receive_ferror
= smtp_ferror
;
2899 receive_smtp_buffered
= smtp_buffered
;
2901 gnutls_deinit(state
->session
);
2902 gnutls_certificate_free_credentials(state
->x509_cred
);
2904 state
->session
= NULL
;
2905 state
->tlsp
->active
.sock
= -1;
2906 state
->tlsp
->active
.tls_ctx
= NULL
;
2907 state
->tlsp
->bits
= 0;
2908 state
->tlsp
->certificate_verified
= FALSE
;
2909 tls_channelbinding_b64
= NULL
;
2910 state
->tlsp
->cipher
= NULL
;
2911 state
->tlsp
->peercert
= NULL
;
2912 state
->tlsp
->peerdn
= NULL
;
2917 /* Handle genuine errors */
2919 else if (inbytes
< 0)
2921 DEBUG(D_tls
) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__
);
2922 record_io_error(state
, (int) inbytes
, US
"recv", NULL
);
2923 state
->xfer_error
= TRUE
;
2926 #ifndef DISABLE_DKIM
2927 dkim_exim_verify_feed(state
->xfer_buffer
, inbytes
);
2929 state
->xfer_buffer_hwm
= (int) inbytes
;
2930 state
->xfer_buffer_lwm
= 0;
2934 /*************************************************
2935 * TLS version of getc *
2936 *************************************************/
2938 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2939 it refills the buffer via the GnuTLS reading function.
2940 Only used by the server-side TLS.
2942 This feeds DKIM and should be used for all message-body reads.
2944 Arguments: lim Maximum amount to read/buffer
2945 Returns: the next character or EOF
2949 tls_getc(unsigned lim
)
2951 exim_gnutls_state_st
* state
= &state_server
;
2953 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
2954 if (!tls_refill(lim
))
2955 return state
->xfer_error
? EOF
: smtp_getc(lim
);
2957 /* Something in the buffer; return next uschar */
2959 return state
->xfer_buffer
[state
->xfer_buffer_lwm
++];
2963 tls_getbuf(unsigned * len
)
2965 exim_gnutls_state_st
* state
= &state_server
;
2969 if (state
->xfer_buffer_lwm
>= state
->xfer_buffer_hwm
)
2970 if (!tls_refill(*len
))
2972 if (!state
->xfer_error
) return smtp_getbuf(len
);
2977 if ((size
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
) > *len
)
2979 buf
= &state
->xfer_buffer
[state
->xfer_buffer_lwm
];
2980 state
->xfer_buffer_lwm
+= size
;
2989 #ifndef DISABLE_DKIM
2990 exim_gnutls_state_st
* state
= &state_server
;
2991 int n
= state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
;
2993 dkim_exim_verify_feed(state
->xfer_buffer
+state
->xfer_buffer_lwm
, n
);
2999 tls_could_read(void)
3001 return state_server
.xfer_buffer_lwm
< state_server
.xfer_buffer_hwm
3002 || gnutls_record_check_pending(state_server
.session
) > 0;
3008 /*************************************************
3009 * Read bytes from TLS channel *
3010 *************************************************/
3012 /* This does not feed DKIM, so if the caller uses this for reading message body,
3013 then the caller must feed DKIM.
3016 ct_ctx client context pointer, or NULL for the one global server context
3020 Returns: the number of bytes read
3021 -1 after a failed read, including EOF
3025 tls_read(void * ct_ctx
, uschar
*buff
, size_t len
)
3027 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3033 if (state
->xfer_buffer_lwm
< state
->xfer_buffer_hwm
)
3035 debug_printf("*** PROBABLY A BUG *** " \
3036 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3037 state
->xfer_buffer_hwm
- state
->xfer_buffer_lwm
);
3040 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT
")\n",
3041 state
->session
, buff
, len
);
3044 inbytes
= gnutls_record_recv(state
->session
, buff
, len
);
3045 while (inbytes
== GNUTLS_E_AGAIN
);
3047 if (inbytes
> 0) return inbytes
;
3050 DEBUG(D_tls
) debug_printf("Got TLS_EOF\n");
3054 DEBUG(D_tls
) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__
);
3055 record_io_error(state
, (int)inbytes
, US
"recv", NULL
);
3064 /*************************************************
3065 * Write bytes down TLS channel *
3066 *************************************************/
3070 ct_ctx client context pointer, or NULL for the one global server context
3073 more more data expected soon
3075 Returns: the number of bytes after a successful write,
3076 -1 after a failed write
3080 tls_write(void * ct_ctx
, const uschar
* buff
, size_t len
, BOOL more
)
3084 exim_gnutls_state_st
* state
= ct_ctx
? ct_ctx
: &state_server
;
3086 static BOOL corked
= FALSE
;
3088 if (more
&& !corked
) gnutls_record_cork(state
->session
);
3091 DEBUG(D_tls
) debug_printf("%s(%p, " SIZE_T_FMT
"%s)\n", __FUNCTION__
,
3092 buff
, left
, more
? ", more" : "");
3096 DEBUG(D_tls
) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT
")\n",
3100 outbytes
= gnutls_record_send(state
->session
, buff
, left
);
3101 while (outbytes
== GNUTLS_E_AGAIN
);
3103 DEBUG(D_tls
) debug_printf("outbytes=" SSIZE_T_FMT
"\n", outbytes
);
3106 DEBUG(D_tls
) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__
);
3107 record_io_error(state
, outbytes
, US
"send", NULL
);
3112 record_io_error(state
, 0, US
"send", US
"TLS channel closed on write");
3123 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT
") than INT_MAX\n",
3131 if (!more
) (void) gnutls_record_uncork(state
->session
, 0);
3142 /*************************************************
3143 * Random number generation *
3144 *************************************************/
3146 /* Pseudo-random number generation. The result is not expected to be
3147 cryptographically strong but not so weak that someone will shoot themselves
3148 in the foot using it as a nonce in input in some email header scheme or
3149 whatever weirdness they'll twist this into. The result should handle fork()
3150 and avoid repeating sequences. OpenSSL handles that for us.
3154 Returns a random number in range [0, max-1]
3157 #ifdef HAVE_GNUTLS_RND
3159 vaguely_random_number(int max
)
3163 uschar smallbuf
[sizeof(r
)];
3168 needed_len
= sizeof(r
);
3169 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3170 asked for a number less than 10. */
3172 for (r
= max
, i
= 0; r
; ++i
)
3178 i
= gnutls_rnd(GNUTLS_RND_NONCE
, smallbuf
, needed_len
);
3181 DEBUG(D_all
) debug_printf("gnutls_rnd() failed, using fallback.\n");
3182 return vaguely_random_number_fallback(max
);
3185 for (uschar
* p
= smallbuf
; needed_len
; --needed_len
, ++p
)
3188 /* We don't particularly care about weighted results; if someone wants
3189 * smooth distribution and cares enough then they should submit a patch then. */
3192 #else /* HAVE_GNUTLS_RND */
3194 vaguely_random_number(int max
)
3196 return vaguely_random_number_fallback(max
);
3198 #endif /* HAVE_GNUTLS_RND */
3203 /*************************************************
3204 * Let tls_require_ciphers be checked at startup *
3205 *************************************************/
3207 /* The tls_require_ciphers option, if set, must be something which the
3210 Returns: NULL on success, or error message
3214 tls_validate_require_cipher(void)
3217 uschar
*expciphers
= NULL
;
3218 gnutls_priority_t priority_cache
;
3220 uschar
* dummy_errstr
;
3222 #define validate_check_rc(Label) do { \
3223 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3224 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3225 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3227 if (exim_gnutls_base_init_done
)
3228 log_write(0, LOG_MAIN
|LOG_PANIC
,
3229 "already initialised GnuTLS, Exim developer bug");
3231 #ifdef HAVE_GNUTLS_PKCS11
3232 if (!gnutls_allow_auto_pkcs11
)
3234 rc
= gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL
, NULL
);
3235 validate_check_rc(US
"gnutls_pkcs11_init");
3238 rc
= gnutls_global_init();
3239 validate_check_rc(US
"gnutls_global_init()");
3240 exim_gnutls_base_init_done
= TRUE
;
3242 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
3243 return_deinit(NULL
);
3245 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
3247 return_deinit(US
"failed to expand tls_require_ciphers");
3249 if (!(expciphers
&& *expciphers
))
3250 return_deinit(NULL
);
3253 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
3255 rc
= gnutls_priority_init(&priority_cache
, CS expciphers
, &errpos
);
3256 validate_check_rc(string_sprintf(
3257 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3258 expciphers
, errpos
- CS expciphers
, errpos
));
3260 #undef return_deinit
3261 #undef validate_check_rc
3262 gnutls_global_deinit();
3270 /*************************************************
3271 * Report the library versions. *
3272 *************************************************/
3274 /* See a description in tls-openssl.c for an explanation of why this exists.
3276 Arguments: a FILE* to print the results to
3281 tls_version_report(FILE *f
)
3283 fprintf(f
, "Library version: GnuTLS: Compile: %s\n"
3286 gnutls_check_version(NULL
));
3289 #endif /*!MACRO_PREDEF*/
3292 /* End of tls-gnu.c */