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 /* Portions Copyright (c) The OpenSSL Project 1999 */
10 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11 library. It is #included into the tls.c file when that library is used. The
12 code herein is based on a patch that was originally contributed by Steve
13 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
15 No cryptographic code is included in Exim. All this module does is to call
16 functions from the OpenSSL library. */
21 #include <openssl/lhash.h>
22 #include <openssl/ssl.h>
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
25 #ifndef OPENSSL_NO_ECDH
26 # include <openssl/ec.h>
29 # include <openssl/ocsp.h>
37 # define EXIM_OCSP_SKEW_SECONDS (300L)
38 # define EXIM_OCSP_MAX_AGE (-1L)
41 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
42 # define EXIM_HAVE_OPENSSL_TLSEXT
44 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
45 # define EXIM_HAVE_RSA_GENKEY_EX
47 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
48 # define EXIM_HAVE_OCSP_RESP_COUNT
50 # define EXIM_HAVE_EPHEM_RSA_KEX
51 # define EXIM_HAVE_RAND_PSEUDO
53 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
54 # define EXIM_HAVE_SHA256
57 /* X509_check_host provides sane certificate hostname checking, but was added
58 to OpenSSL late, after other projects forked off the code-base. So in
59 addition to guarding against the base version number, beware that LibreSSL
60 does not (at this time) support this function.
62 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
63 opt to disentangle and ask a LibreSSL user to provide glue for a third
64 crypto provider for libtls instead of continuing to tie the OpenSSL glue
65 into even twistier knots. If LibreSSL gains the same API, we can just
66 change this guard and punt the issue for a while longer. */
68 #ifndef LIBRESSL_VERSION_NUMBER
69 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
70 # define EXIM_HAVE_OPENSSL_CHECKHOST
71 # define EXIM_HAVE_OPENSSL_DH_BITS
72 # define EXIM_HAVE_OPENSSL_TLS_METHOD
74 # define EXIM_NEED_OPENSSL_INIT
76 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
77 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
78 # define EXIM_HAVE_OPENSSL_CHECKHOST
82 #if !defined(LIBRESSL_VERSION_NUMBER) \
83 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
84 # if !defined(OPENSSL_NO_ECDH)
85 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
86 # define EXIM_HAVE_ECDH
88 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
89 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
94 #ifndef LIBRESSL_VERSION_NUMBER
95 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
96 # define OPENSSL_HAVE_KEYLOG_CB
97 # define OPENSSL_HAVE_NUM_TICKETS
101 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
102 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
103 # define DISABLE_OCSP
106 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
107 # include <openssl/x509v3.h>
110 /*************************************************
111 * OpenSSL option parse *
112 *************************************************/
114 typedef struct exim_openssl_option
{
117 } exim_openssl_option
;
118 /* We could use a macro to expand, but we need the ifdef and not all the
119 options document which version they were introduced in. Policylet: include
120 all options unless explicitly for DTLS, let the administrator choose which
123 This list is current as of:
125 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
126 Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev
128 static exim_openssl_option exim_openssl_options
[] = {
129 /* KEEP SORTED ALPHABETICALLY! */
131 { US
"all", SSL_OP_ALL
},
133 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
134 { US
"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
},
136 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
137 { US
"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE
},
139 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
140 { US
"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
},
142 #ifdef SSL_OP_EPHEMERAL_RSA
143 { US
"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA
},
145 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
146 { US
"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT
},
148 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
149 { US
"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
},
151 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
152 { US
"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG
},
154 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
155 { US
"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING
},
157 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
158 { US
"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG
},
160 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
161 { US
"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
},
163 #ifdef SSL_OP_NO_COMPRESSION
164 { US
"no_compression", SSL_OP_NO_COMPRESSION
},
166 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
167 { US
"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
},
169 #ifdef SSL_OP_NO_SSLv2
170 { US
"no_sslv2", SSL_OP_NO_SSLv2
},
172 #ifdef SSL_OP_NO_SSLv3
173 { US
"no_sslv3", SSL_OP_NO_SSLv3
},
175 #ifdef SSL_OP_NO_TICKET
176 { US
"no_ticket", SSL_OP_NO_TICKET
},
178 #ifdef SSL_OP_NO_TLSv1
179 { US
"no_tlsv1", SSL_OP_NO_TLSv1
},
181 #ifdef SSL_OP_NO_TLSv1_1
182 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
183 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
184 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
186 { US
"no_tlsv1_1", SSL_OP_NO_TLSv1_1
},
189 #ifdef SSL_OP_NO_TLSv1_2
190 { US
"no_tlsv1_2", SSL_OP_NO_TLSv1_2
},
192 #ifdef SSL_OP_NO_TLSv1_3
193 { US
"no_tlsv1_3", SSL_OP_NO_TLSv1_3
},
195 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
196 { US
"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG
},
198 #ifdef SSL_OP_SINGLE_DH_USE
199 { US
"single_dh_use", SSL_OP_SINGLE_DH_USE
},
201 #ifdef SSL_OP_SINGLE_ECDH_USE
202 { US
"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE
},
204 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
205 { US
"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG
},
207 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
208 { US
"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
},
210 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
211 { US
"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG
},
213 #ifdef SSL_OP_TLS_D5_BUG
214 { US
"tls_d5_bug", SSL_OP_TLS_D5_BUG
},
216 #ifdef SSL_OP_TLS_ROLLBACK_BUG
217 { US
"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG
},
222 static int exim_openssl_options_size
= nelem(exim_openssl_options
);
231 for (struct exim_openssl_option
* o
= exim_openssl_options
;
232 o
< exim_openssl_options
+ nelem(exim_openssl_options
); o
++)
234 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
235 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
237 spf(buf
, sizeof(buf
), US
"_OPT_OPENSSL_%T_X", o
->name
);
238 builtin_macro_create(buf
);
243 /******************************************************************************/
245 /* Structure for collecting random data for seeding. */
247 typedef struct randstuff
{
252 /* Local static variables */
254 static BOOL client_verify_callback_called
= FALSE
;
255 static BOOL server_verify_callback_called
= FALSE
;
256 static const uschar
*sid_ctx
= US
"exim";
258 /* We have three different contexts to care about.
260 Simple case: client, `client_ctx`
261 As a client, we can be doing a callout or cut-through delivery while receiving
262 a message. So we have a client context, which should have options initialised
263 from the SMTP Transport. We may also concurrently want to make TLS connections
264 to utility daemons, so client-contexts are allocated and passed around in call
265 args rather than using a gobal.
268 There are two cases: with and without ServerNameIndication from the client.
269 Given TLS SNI, we can be using different keys, certs and various other
270 configuration settings, because they're re-expanded with $tls_sni set. This
271 allows vhosting with TLS. This SNI is sent in the handshake.
272 A client might not send SNI, so we need a fallback, and an initial setup too.
273 So as a server, we start out using `server_ctx`.
274 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
275 `server_sni` from `server_ctx` and then initialise settings by re-expanding
282 } exim_openssl_client_tls_ctx
;
284 static SSL_CTX
*server_ctx
= NULL
;
285 static SSL
*server_ssl
= NULL
;
287 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
288 static SSL_CTX
*server_sni
= NULL
;
291 static char ssl_errstring
[256];
293 static int ssl_session_timeout
= 200;
294 static BOOL client_verify_optional
= FALSE
;
295 static BOOL server_verify_optional
= FALSE
;
297 static BOOL reexpand_tls_files_for_sni
= FALSE
;
300 typedef struct tls_ext_ctx_cb
{
305 STACK_OF(X509
) *verify_stack
; /* chain for verifying the proof */
309 uschar
*file_expanded
;
310 OCSP_RESPONSE
*response
;
313 X509_STORE
*verify_store
; /* non-null if status requested */
314 BOOL verify_required
;
319 /* these are cached from first expand */
320 uschar
*server_cipher_list
;
321 /* only passed down to tls_error: */
323 const uschar
* verify_cert_hostnames
;
324 #ifndef DISABLE_EVENT
325 uschar
* event_action
;
329 /* should figure out a cleanup of API to handle state preserved per
330 implementation, for various reasons, which can be void * in the APIs.
331 For now, we hack around it. */
332 tls_ext_ctx_cb
*client_static_cbinfo
= NULL
;
333 tls_ext_ctx_cb
*server_static_cbinfo
= NULL
;
336 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
337 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*), uschar
** errstr
);
340 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
341 static int tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
);
344 static int tls_server_stapling_cb(SSL
*s
, void *arg
);
348 /*************************************************
350 *************************************************/
352 /* Called from lots of places when errors occur before actually starting to do
353 the TLS handshake, that is, while the session is still in clear. Always returns
354 DEFER for a server and FAIL for a client so that most calls can use "return
355 tls_error(...)" to do this processing and then give an appropriate return. A
356 single function is used for both server and client, because it is called from
357 some shared functions.
360 prefix text to include in the logged error
361 host NULL if setting up a server;
362 the connected host if setting up a client
363 msg error message or NULL if we should ask OpenSSL
364 errstr pointer to output error message
366 Returns: OK/DEFER/FAIL
370 tls_error(uschar
* prefix
, const host_item
* host
, uschar
* msg
, uschar
** errstr
)
374 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
375 msg
= US ssl_errstring
;
378 msg
= string_sprintf("(%s): %s", prefix
, msg
);
379 DEBUG(D_tls
) debug_printf("TLS error '%s'\n", msg
);
380 if (errstr
) *errstr
= msg
;
381 return host
? FAIL
: DEFER
;
386 /*************************************************
387 * Callback to generate RSA key *
388 *************************************************/
392 s SSL connection (not used)
396 Returns: pointer to generated key
400 rsa_callback(SSL
*s
, int export
, int keylength
)
403 #ifdef EXIM_HAVE_RSA_GENKEY_EX
404 BIGNUM
*bn
= BN_new();
407 export
= export
; /* Shut picky compilers up */
408 DEBUG(D_tls
) debug_printf("Generating %d bit RSA key...\n", keylength
);
410 #ifdef EXIM_HAVE_RSA_GENKEY_EX
411 if ( !BN_set_word(bn
, (unsigned long)RSA_F4
)
412 || !(rsa_key
= RSA_new())
413 || !RSA_generate_key_ex(rsa_key
, keylength
, bn
, NULL
)
416 if (!(rsa_key
= RSA_generate_key(keylength
, RSA_F4
, NULL
, NULL
)))
420 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
421 log_write(0, LOG_MAIN
|LOG_PANIC
, "TLS error (RSA_generate_key): %s",
433 x509_store_dump_cert_s_names(X509_STORE * store)
435 STACK_OF(X509_OBJECT) * roots= store->objs;
436 static uschar name[256];
438 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
440 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
441 if(tmp_obj->type == X509_LU_X509)
443 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
444 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
446 name[sizeof(name)-1] = '\0';
447 debug_printf(" %s\n", name);
456 #ifndef DISABLE_EVENT
458 verify_event(tls_support
* tlsp
, X509
* cert
, int depth
, const uschar
* dn
,
459 BOOL
*calledp
, const BOOL
*optionalp
, const uschar
* what
)
465 ev
= tlsp
== &tls_out
? client_static_cbinfo
->event_action
: event_action
;
468 DEBUG(D_tls
) debug_printf("verify_event: %s %d\n", what
, depth
);
469 old_cert
= tlsp
->peercert
;
470 tlsp
->peercert
= X509_dup(cert
);
471 /* NB we do not bother setting peerdn */
472 if ((yield
= event_raise(ev
, US
"tls:cert", string_sprintf("%d", depth
))))
474 log_write(0, LOG_MAIN
, "[%s] %s verify denied by event-action: "
475 "depth=%d cert=%s: %s",
476 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
477 what
, depth
, dn
, yield
);
481 if (old_cert
) tlsp
->peercert
= old_cert
; /* restore 1st failing cert */
482 return 1; /* reject (leaving peercert set) */
484 DEBUG(D_tls
) debug_printf("Event-action verify failure overridden "
485 "(host in tls_try_verify_hosts)\n");
487 X509_free(tlsp
->peercert
);
488 tlsp
->peercert
= old_cert
;
494 /*************************************************
495 * Callback for verification *
496 *************************************************/
498 /* The SSL library does certificate verification if set up to do so. This
499 callback has the current yes/no state is in "state". If verification succeeded,
500 we set the certificate-verified flag. If verification failed, what happens
501 depends on whether the client is required to present a verifiable certificate
504 If verification is optional, we change the state to yes, but still log the
505 verification error. For some reason (it really would help to have proper
506 documentation of OpenSSL), this callback function then gets called again, this
507 time with state = 1. We must take care not to set the private verified flag on
508 the second time through.
510 Note: this function is not called if the client fails to present a certificate
511 when asked. We get here only if a certificate has been received. Handling of
512 optional verification for this case is done when requesting SSL to verify, by
513 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
515 May be called multiple times for different issues with a certificate, even
516 for a given "depth" in the certificate chain.
519 preverify_ok current yes/no state as 1/0
520 x509ctx certificate information.
521 tlsp per-direction (client vs. server) support data
522 calledp has-been-called flag
523 optionalp verification-is-optional flag
525 Returns: 0 if verification should fail, otherwise 1
529 verify_callback(int preverify_ok
, X509_STORE_CTX
* x509ctx
,
530 tls_support
* tlsp
, BOOL
* calledp
, BOOL
* optionalp
)
532 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
533 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
536 if (!X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
)))
538 DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n");
539 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
540 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
);
543 dn
[sizeof(dn
)-1] = '\0';
545 if (preverify_ok
== 0)
547 uschar
* extra
= verify_mode
? string_sprintf(" (during %c-verify for [%s])",
548 *verify_mode
, sender_host_address
)
550 log_write(0, LOG_MAIN
, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
551 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
553 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx
)), dn
);
558 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
559 return 0; /* reject */
561 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
562 "tls_try_verify_hosts)\n");
567 DEBUG(D_tls
) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth
, dn
);
569 if (tlsp
== &tls_out
&& client_static_cbinfo
->u_ocsp
.client
.verify_store
)
570 { /* client, wanting stapling */
571 /* Add the server cert's signing chain as the one
572 for the verification of the OCSP stapled information. */
574 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
577 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
580 #ifndef DISABLE_EVENT
581 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
582 return 0; /* reject, with peercert set */
587 const uschar
* verify_cert_hostnames
;
589 if ( tlsp
== &tls_out
590 && ((verify_cert_hostnames
= client_static_cbinfo
->verify_cert_hostnames
)))
591 /* client, wanting hostname check */
594 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
595 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
596 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
598 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
599 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
602 const uschar
* list
= verify_cert_hostnames
;
605 while ((name
= string_nextinlist(&list
, &sep
, NULL
, 0)))
606 if ((rc
= X509_check_host(cert
, CCS name
, 0,
607 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
608 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
,
613 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
614 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
);
621 if (!tls_is_name_for_cert(verify_cert_hostnames
, cert
))
624 uschar
* extra
= verify_mode
625 ? string_sprintf(" (during %c-verify for [%s])",
626 *verify_mode
, sender_host_address
)
628 log_write(0, LOG_MAIN
,
629 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
630 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
631 extra
, dn
, verify_cert_hostnames
);
636 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
637 return 0; /* reject */
639 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
640 "tls_try_verify_hosts)\n");
644 #ifndef DISABLE_EVENT
645 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
646 return 0; /* reject, with peercert set */
649 DEBUG(D_tls
) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
650 *calledp
? "" : " authenticated", dn
);
651 if (!*calledp
) tlsp
->certificate_verified
= TRUE
;
655 return 1; /* accept, at least for this level */
659 verify_callback_client(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
661 return verify_callback(preverify_ok
, x509ctx
, &tls_out
,
662 &client_verify_callback_called
, &client_verify_optional
);
666 verify_callback_server(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
668 return verify_callback(preverify_ok
, x509ctx
, &tls_in
,
669 &server_verify_callback_called
, &server_verify_optional
);
675 /* This gets called *by* the dane library verify callback, which interposes
679 verify_callback_client_dane(int preverify_ok
, X509_STORE_CTX
* x509ctx
)
681 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
683 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
684 #ifndef DISABLE_EVENT
685 BOOL dummy_called
, optional
= FALSE
;
688 if (!X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
)))
690 DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n");
691 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
692 deliver_host_address
);
695 dn
[sizeof(dn
)-1] = '\0';
697 DEBUG(D_tls
) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
698 preverify_ok
? "ok":"BAD", depth
, dn
);
700 #ifndef DISABLE_EVENT
701 if (verify_event(&tls_out
, cert
, depth
, dn
,
702 &dummy_called
, &optional
, US
"DANE"))
703 return 0; /* reject, with peercert set */
706 if (preverify_ok
== 1)
708 tls_out
.dane_verified
= tls_out
.certificate_verified
= TRUE
;
710 if (client_static_cbinfo
->u_ocsp
.client
.verify_store
)
711 { /* client, wanting stapling */
712 /* Add the server cert's signing chain as the one
713 for the verification of the OCSP stapled information. */
715 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
718 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
724 int err
= X509_STORE_CTX_get_error(x509ctx
);
726 debug_printf(" - err %d '%s'\n", err
, X509_verify_cert_error_string(err
));
727 if (err
== X509_V_ERR_APPLICATION_VERIFICATION
)
733 #endif /*SUPPORT_DANE*/
736 /*************************************************
737 * Information callback *
738 *************************************************/
740 /* The SSL library functions call this from time to time to indicate what they
741 are doing. We copy the string to the debugging output when TLS debugging has
753 info_callback(SSL
*s
, int where
, int ret
)
759 if (where
& SSL_ST_CONNECT
)
760 str
= US
"SSL_connect";
761 else if (where
& SSL_ST_ACCEPT
)
762 str
= US
"SSL_accept";
764 str
= US
"SSL info (undefined)";
766 if (where
& SSL_CB_LOOP
)
767 debug_printf("%s: %s\n", str
, SSL_state_string_long(s
));
768 else if (where
& SSL_CB_ALERT
)
769 debug_printf("SSL3 alert %s:%s:%s\n",
770 str
= where
& SSL_CB_READ
? US
"read" : US
"write",
771 SSL_alert_type_string_long(ret
), SSL_alert_desc_string_long(ret
));
772 else if (where
& SSL_CB_EXIT
)
774 debug_printf("%s: failed in %s\n", str
, SSL_state_string_long(s
));
776 debug_printf("%s: error in %s\n", str
, SSL_state_string_long(s
));
777 else if (where
& SSL_CB_HANDSHAKE_START
)
778 debug_printf("%s: hshake start: %s\n", str
, SSL_state_string_long(s
));
779 else if (where
& SSL_CB_HANDSHAKE_DONE
)
780 debug_printf("%s: hshake done: %s\n", str
, SSL_state_string_long(s
));
785 keylog_callback(const SSL
*ssl
, const char *line
)
787 DEBUG(D_tls
) debug_printf("%.200s\n", line
);
792 /*************************************************
793 * Initialize for DH *
794 *************************************************/
796 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
799 sctx The current SSL CTX (inbound or outbound)
800 dhparam DH parameter file or fixed parameter identity string
801 host connected host, if client; NULL if server
802 errstr error string pointer
804 Returns: TRUE if OK (nothing to set up, or setup worked)
808 init_dh(SSL_CTX
*sctx
, uschar
*dhparam
, const host_item
*host
, uschar
** errstr
)
816 if (!expand_check(dhparam
, US
"tls_dhparam", &dhexpanded
, errstr
))
819 if (!dhexpanded
|| !*dhexpanded
)
820 bio
= BIO_new_mem_buf(CS
std_dh_prime_default(), -1);
821 else if (dhexpanded
[0] == '/')
823 if (!(bio
= BIO_new_file(CS dhexpanded
, "r")))
825 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded
),
826 host
, US
strerror(errno
), errstr
);
832 if (Ustrcmp(dhexpanded
, "none") == 0)
834 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
838 if (!(pem
= std_dh_prime_named(dhexpanded
)))
840 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded
),
841 host
, US
strerror(errno
), errstr
);
844 bio
= BIO_new_mem_buf(CS pem
, -1);
847 if (!(dh
= PEM_read_bio_DHparams(bio
, NULL
, NULL
, NULL
)))
850 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded
),
855 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
856 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
857 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
858 * If someone wants to dance at the edge, then they can raise the limit or use
859 * current libraries. */
860 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
861 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
862 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
863 dh_bitsize
= DH_bits(dh
);
865 dh_bitsize
= 8 * DH_size(dh
);
868 /* Even if it is larger, we silently return success rather than cause things
869 * to fail out, so that a too-large DH will not knock out all TLS; it's a
870 * debatable choice. */
871 if (dh_bitsize
> tls_dh_max_bits
)
874 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
875 dh_bitsize
, tls_dh_max_bits
);
879 SSL_CTX_set_tmp_dh(sctx
, dh
);
881 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
882 dhexpanded
? dhexpanded
: US
"default", dh_bitsize
);
894 /*************************************************
895 * Initialize for ECDH *
896 *************************************************/
898 /* Load parameters for ECDH encryption.
900 For now, we stick to NIST P-256 because: it's simple and easy to configure;
901 it avoids any patent issues that might bite redistributors; despite events in
902 the news and concerns over curve choices, we're not cryptographers, we're not
903 pretending to be, and this is "good enough" to be better than no support,
904 protecting against most adversaries. Given another year or two, there might
905 be sufficient clarity about a "right" way forward to let us make an informed
906 decision, instead of a knee-jerk reaction.
908 Longer-term, we should look at supporting both various named curves and
909 external files generated with "openssl ecparam", much as we do for init_dh().
910 We should also support "none" as a value, to explicitly avoid initialisation.
915 sctx The current SSL CTX (inbound or outbound)
916 host connected host, if client; NULL if server
917 errstr error string pointer
919 Returns: TRUE if OK (nothing to set up, or setup worked)
923 init_ecdh(SSL_CTX
* sctx
, host_item
* host
, uschar
** errstr
)
925 #ifdef OPENSSL_NO_ECDH
934 if (host
) /* No ECDH setup for clients, only for servers */
937 # ifndef EXIM_HAVE_ECDH
939 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
943 if (!expand_check(tls_eccurve
, US
"tls_eccurve", &exp_curve
, errstr
))
945 if (!exp_curve
|| !*exp_curve
)
948 /* "auto" needs to be handled carefully.
949 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
950 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
951 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
952 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
953 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
955 if (Ustrcmp(exp_curve
, "auto") == 0)
957 #if OPENSSL_VERSION_NUMBER < 0x10002000L
958 DEBUG(D_tls
) debug_printf(
959 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
960 exp_curve
= US
"prime256v1";
962 # if defined SSL_CTRL_SET_ECDH_AUTO
963 DEBUG(D_tls
) debug_printf(
964 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
965 SSL_CTX_set_ecdh_auto(sctx
, 1);
968 DEBUG(D_tls
) debug_printf(
969 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
975 DEBUG(D_tls
) debug_printf("ECDH: curve '%s'\n", exp_curve
);
976 if ( (nid
= OBJ_sn2nid (CCS exp_curve
)) == NID_undef
977 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
978 && (nid
= EC_curve_nist2nid(CCS exp_curve
)) == NID_undef
982 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve
),
987 if (!(ecdh
= EC_KEY_new_by_curve_name(nid
)))
989 tls_error(US
"Unable to create ec curve", host
, NULL
, errstr
);
993 /* The "tmp" in the name here refers to setting a temporary key
994 not to the stability of the interface. */
996 if ((rv
= SSL_CTX_set_tmp_ecdh(sctx
, ecdh
) == 0))
997 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve
), host
, NULL
, errstr
);
999 DEBUG(D_tls
) debug_printf("ECDH: enabled '%s' curve\n", exp_curve
);
1004 # endif /*EXIM_HAVE_ECDH*/
1005 #endif /*OPENSSL_NO_ECDH*/
1011 #ifndef DISABLE_OCSP
1012 /*************************************************
1013 * Load OCSP information into state *
1014 *************************************************/
1015 /* Called to load the server OCSP response from the given file into memory, once
1016 caller has determined this is needed. Checks validity. Debugs a message
1019 ASSUMES: single response, for single cert.
1022 sctx the SSL_CTX* to update
1023 cbinfo various parts of session state
1024 expanded the filename putatively holding an OCSP response
1029 ocsp_load_response(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
, const uschar
*expanded
)
1032 OCSP_RESPONSE
* resp
;
1033 OCSP_BASICRESP
* basic_response
;
1034 OCSP_SINGLERESP
* single_response
;
1035 ASN1_GENERALIZEDTIME
* rev
, * thisupd
, * nextupd
;
1036 STACK_OF(X509
) * sk
;
1037 unsigned long verify_flags
;
1038 int status
, reason
, i
;
1040 cbinfo
->u_ocsp
.server
.file_expanded
= string_copy(expanded
);
1041 if (cbinfo
->u_ocsp
.server
.response
)
1043 OCSP_RESPONSE_free(cbinfo
->u_ocsp
.server
.response
);
1044 cbinfo
->u_ocsp
.server
.response
= NULL
;
1047 if (!(bio
= BIO_new_file(CS cbinfo
->u_ocsp
.server
.file_expanded
, "rb")))
1049 DEBUG(D_tls
) debug_printf("Failed to open OCSP response file \"%s\"\n",
1050 cbinfo
->u_ocsp
.server
.file_expanded
);
1054 resp
= d2i_OCSP_RESPONSE_bio(bio
, NULL
);
1058 DEBUG(D_tls
) debug_printf("Error reading OCSP response.\n");
1062 if ((status
= OCSP_response_status(resp
)) != OCSP_RESPONSE_STATUS_SUCCESSFUL
)
1064 DEBUG(D_tls
) debug_printf("OCSP response not valid: %s (%d)\n",
1065 OCSP_response_status_str(status
), status
);
1069 if (!(basic_response
= OCSP_response_get1_basic(resp
)))
1072 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1076 sk
= cbinfo
->verify_stack
;
1077 verify_flags
= OCSP_NOVERIFY
; /* check sigs, but not purpose */
1079 /* May need to expose ability to adjust those flags?
1080 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1081 OCSP_TRUSTOTHER OCSP_NOINTERN */
1083 /* This does a full verify on the OCSP proof before we load it for serving
1084 up; possibly overkill - just date-checks might be nice enough.
1086 OCSP_basic_verify takes a "store" arg, but does not
1087 use it for the chain verification, which is all we do
1088 when OCSP_NOVERIFY is set. The content from the wire
1089 "basic_response" and a cert-stack "sk" are all that is used.
1091 We have a stack, loaded in setup_certs() if tls_verify_certificates
1092 was a file (not a directory, or "system"). It is unfortunate we
1093 cannot used the connection context store, as that would neatly
1094 handle the "system" case too, but there seems to be no library
1095 function for getting a stack from a store.
1096 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1097 We do not free the stack since it could be needed a second time for
1100 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1101 be a public interface into the OpenSSL library (there's no manual entry) -
1102 But what with? We also use OCSP_basic_verify in the client stapling callback.
1103 And there we NEED it; we must verify that status... unless the
1104 library does it for us anyway? */
1106 if ((i
= OCSP_basic_verify(basic_response
, sk
, NULL
, verify_flags
)) < 0)
1110 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
1111 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring
);
1116 /* Here's the simplifying assumption: there's only one response, for the
1117 one certificate we use, and nothing for anything else in a chain. If this
1118 proves false, we need to extract a cert id from our issued cert
1119 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1120 right cert in the stack and then calls OCSP_single_get0_status()).
1122 I'm hoping to avoid reworking a bunch more of how we handle state here. */
1124 if (!(single_response
= OCSP_resp_get0(basic_response
, 0)))
1127 debug_printf("Unable to get first response from OCSP basic response.\n");
1131 status
= OCSP_single_get0_status(single_response
, &reason
, &rev
, &thisupd
, &nextupd
);
1132 if (status
!= V_OCSP_CERTSTATUS_GOOD
)
1134 DEBUG(D_tls
) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1135 OCSP_cert_status_str(status
), status
,
1136 OCSP_crl_reason_str(reason
), reason
);
1140 if (!OCSP_check_validity(thisupd
, nextupd
, EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1142 DEBUG(D_tls
) debug_printf("OCSP status invalid times.\n");
1147 cbinfo
->u_ocsp
.server
.response
= resp
; /*XXX stack?*/
1151 if (f
.running_in_test_harness
)
1153 extern char ** environ
;
1154 if (environ
) for (uschar
** p
= USS environ
; *p
; p
++)
1155 if (Ustrncmp(*p
, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1157 DEBUG(D_tls
) debug_printf("Supplying known bad OCSP response\n");
1158 goto supply_response
;
1163 #endif /*!DISABLE_OCSP*/
1168 /* Create and install a selfsigned certificate, for use in server mode */
1171 tls_install_selfsign(SSL_CTX
* sctx
, uschar
** errstr
)
1179 where
= US
"allocating pkey";
1180 if (!(pkey
= EVP_PKEY_new()))
1183 where
= US
"allocating cert";
1184 if (!(x509
= X509_new()))
1187 where
= US
"generating pkey";
1188 if (!(rsa
= rsa_callback(NULL
, 0, 2048)))
1191 where
= US
"assigning pkey";
1192 if (!EVP_PKEY_assign_RSA(pkey
, rsa
))
1195 X509_set_version(x509
, 2); /* N+1 - version 3 */
1196 ASN1_INTEGER_set(X509_get_serialNumber(x509
), 1);
1197 X509_gmtime_adj(X509_get_notBefore(x509
), 0);
1198 X509_gmtime_adj(X509_get_notAfter(x509
), (long)60 * 60); /* 1 hour */
1199 X509_set_pubkey(x509
, pkey
);
1201 name
= X509_get_subject_name(x509
);
1202 X509_NAME_add_entry_by_txt(name
, "C",
1203 MBSTRING_ASC
, CUS
"UK", -1, -1, 0);
1204 X509_NAME_add_entry_by_txt(name
, "O",
1205 MBSTRING_ASC
, CUS
"Exim Developers", -1, -1, 0);
1206 X509_NAME_add_entry_by_txt(name
, "CN",
1207 MBSTRING_ASC
, CUS smtp_active_hostname
, -1, -1, 0);
1208 X509_set_issuer_name(x509
, name
);
1210 where
= US
"signing cert";
1211 if (!X509_sign(x509
, pkey
, EVP_md5()))
1214 where
= US
"installing selfsign cert";
1215 if (!SSL_CTX_use_certificate(sctx
, x509
))
1218 where
= US
"installing selfsign key";
1219 if (!SSL_CTX_use_PrivateKey(sctx
, pkey
))
1225 (void) tls_error(where
, NULL
, NULL
, errstr
);
1226 if (x509
) X509_free(x509
);
1227 if (pkey
) EVP_PKEY_free(pkey
);
1235 tls_add_certfile(SSL_CTX
* sctx
, tls_ext_ctx_cb
* cbinfo
, uschar
* file
,
1238 DEBUG(D_tls
) debug_printf("tls_certificate file %s\n", file
);
1239 if (!SSL_CTX_use_certificate_chain_file(sctx
, CS file
))
1240 return tls_error(string_sprintf(
1241 "SSL_CTX_use_certificate_chain_file file=%s", file
),
1242 cbinfo
->host
, NULL
, errstr
);
1247 tls_add_pkeyfile(SSL_CTX
* sctx
, tls_ext_ctx_cb
* cbinfo
, uschar
* file
,
1250 DEBUG(D_tls
) debug_printf("tls_privatekey file %s\n", file
);
1251 if (!SSL_CTX_use_PrivateKey_file(sctx
, CS file
, SSL_FILETYPE_PEM
))
1252 return tls_error(string_sprintf(
1253 "SSL_CTX_use_PrivateKey_file file=%s", file
), cbinfo
->host
, NULL
, errstr
);
1258 /*************************************************
1259 * Expand key and cert file specs *
1260 *************************************************/
1262 /* Called once during tls_init and possibly again during TLS setup, for a
1263 new context, if Server Name Indication was used and tls_sni was seen in
1264 the certificate string.
1267 sctx the SSL_CTX* to update
1268 cbinfo various parts of session state
1269 errstr error string pointer
1271 Returns: OK/DEFER/FAIL
1275 tls_expand_session_files(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
,
1280 if (!cbinfo
->certificate
)
1282 if (!cbinfo
->is_server
) /* client */
1285 if (tls_install_selfsign(sctx
, errstr
) != OK
)
1292 if (Ustrstr(cbinfo
->certificate
, US
"tls_sni") ||
1293 Ustrstr(cbinfo
->certificate
, US
"tls_in_sni") ||
1294 Ustrstr(cbinfo
->certificate
, US
"tls_out_sni")
1296 reexpand_tls_files_for_sni
= TRUE
;
1298 if (!expand_check(cbinfo
->certificate
, US
"tls_certificate", &expanded
, errstr
))
1302 if (cbinfo
->is_server
)
1304 const uschar
* file_list
= expanded
;
1308 while (file
= string_nextinlist(&file_list
, &sep
, NULL
, 0))
1309 if ((err
= tls_add_certfile(sctx
, cbinfo
, file
, errstr
)))
1312 else /* would there ever be a need for multiple client certs? */
1313 if ((err
= tls_add_certfile(sctx
, cbinfo
, expanded
, errstr
)))
1316 if ( cbinfo
->privatekey
1317 && !expand_check(cbinfo
->privatekey
, US
"tls_privatekey", &expanded
, errstr
))
1320 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1321 of the expansion is an empty string, ignore it also, and assume the private
1322 key is in the same file as the certificate. */
1324 if (expanded
&& *expanded
)
1325 if (cbinfo
->is_server
)
1327 const uschar
* file_list
= expanded
;
1331 while (file
= string_nextinlist(&file_list
, &sep
, NULL
, 0))
1332 if ((err
= tls_add_pkeyfile(sctx
, cbinfo
, file
, errstr
)))
1335 else /* would there ever be a need for multiple client certs? */
1336 if ((err
= tls_add_pkeyfile(sctx
, cbinfo
, expanded
, errstr
)))
1340 #ifndef DISABLE_OCSP
1341 if (cbinfo
->is_server
&& cbinfo
->u_ocsp
.server
.file
)
1344 if (!expand_check(cbinfo
->u_ocsp
.server
.file
, US
"tls_ocsp_file", &expanded
, errstr
))
1347 if (expanded
&& *expanded
)
1349 DEBUG(D_tls
) debug_printf("tls_ocsp_file %s\n", expanded
);
1350 if ( cbinfo
->u_ocsp
.server
.file_expanded
1351 && (Ustrcmp(expanded
, cbinfo
->u_ocsp
.server
.file_expanded
) == 0))
1353 DEBUG(D_tls
) debug_printf(" - value unchanged, using existing values\n");
1356 ocsp_load_response(sctx
, cbinfo
, expanded
);
1367 /*************************************************
1368 * Callback to handle SNI *
1369 *************************************************/
1371 /* Called when acting as server during the TLS session setup if a Server Name
1372 Indication extension was sent by the client.
1374 API documentation is OpenSSL s_server.c implementation.
1377 s SSL* of the current session
1378 ad unknown (part of OpenSSL API) (unused)
1379 arg Callback of "our" registered data
1381 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1384 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1386 tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
)
1388 const char *servername
= SSL_get_servername(s
, TLSEXT_NAMETYPE_host_name
);
1389 tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1391 int old_pool
= store_pool
;
1392 uschar
* dummy_errstr
;
1395 return SSL_TLSEXT_ERR_OK
;
1397 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", servername
,
1398 reexpand_tls_files_for_sni
? "" : " (unused for certificate selection)");
1400 /* Make the extension value available for expansion */
1401 store_pool
= POOL_PERM
;
1402 tls_in
.sni
= string_copy(US servername
);
1403 store_pool
= old_pool
;
1405 if (!reexpand_tls_files_for_sni
)
1406 return SSL_TLSEXT_ERR_OK
;
1408 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1409 not confident that memcpy wouldn't break some internal reference counting.
1410 Especially since there's a references struct member, which would be off. */
1412 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1413 if (!(server_sni
= SSL_CTX_new(TLS_server_method())))
1415 if (!(server_sni
= SSL_CTX_new(SSLv23_server_method())))
1418 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
1419 DEBUG(D_tls
) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring
);
1423 /* Not sure how many of these are actually needed, since SSL object
1424 already exists. Might even need this selfsame callback, for reneg? */
1426 SSL_CTX_set_info_callback(server_sni
, SSL_CTX_get_info_callback(server_ctx
));
1427 SSL_CTX_set_mode(server_sni
, SSL_CTX_get_mode(server_ctx
));
1428 SSL_CTX_set_options(server_sni
, SSL_CTX_get_options(server_ctx
));
1429 SSL_CTX_set_timeout(server_sni
, SSL_CTX_get_timeout(server_ctx
));
1430 SSL_CTX_set_tlsext_servername_callback(server_sni
, tls_servername_cb
);
1431 SSL_CTX_set_tlsext_servername_arg(server_sni
, cbinfo
);
1433 if ( !init_dh(server_sni
, cbinfo
->dhparam
, NULL
, &dummy_errstr
)
1434 || !init_ecdh(server_sni
, NULL
, &dummy_errstr
)
1438 if ( cbinfo
->server_cipher_list
1439 && !SSL_CTX_set_cipher_list(server_sni
, CS cbinfo
->server_cipher_list
))
1442 #ifndef DISABLE_OCSP
1443 if (cbinfo
->u_ocsp
.server
.file
)
1445 SSL_CTX_set_tlsext_status_cb(server_sni
, tls_server_stapling_cb
);
1446 SSL_CTX_set_tlsext_status_arg(server_sni
, cbinfo
);
1450 if ((rc
= setup_certs(server_sni
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
,
1451 verify_callback_server
, &dummy_errstr
)) != OK
)
1454 /* do this after setup_certs, because this can require the certs for verifying
1455 OCSP information. */
1456 if ((rc
= tls_expand_session_files(server_sni
, cbinfo
, &dummy_errstr
)) != OK
)
1459 DEBUG(D_tls
) debug_printf("Switching SSL context.\n");
1460 SSL_set_SSL_CTX(s
, server_sni
);
1461 return SSL_TLSEXT_ERR_OK
;
1463 bad
: return SSL_TLSEXT_ERR_ALERT_FATAL
;
1465 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1470 #ifndef DISABLE_OCSP
1472 /*************************************************
1473 * Callback to handle OCSP Stapling *
1474 *************************************************/
1476 /* Called when acting as server during the TLS session setup if the client
1477 requests OCSP information with a Certificate Status Request.
1479 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1485 tls_server_stapling_cb(SSL
*s
, void *arg
)
1487 const tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1488 uschar
*response_der
; /*XXX blob */
1489 int response_der_len
;
1491 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1492 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1493 buggy in current OpenSSL; it returns the last cert loaded always rather than
1494 the one actually presented. So we can't support a stack of OCSP proofs at
1498 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1499 cbinfo
->u_ocsp
.server
.response
? "have" : "lack");
1501 tls_in
.ocsp
= OCSP_NOT_RESP
;
1502 if (!cbinfo
->u_ocsp
.server
.response
)
1503 return SSL_TLSEXT_ERR_NOACK
;
1505 response_der
= NULL
;
1506 response_der_len
= i2d_OCSP_RESPONSE(cbinfo
->u_ocsp
.server
.response
, /*XXX stack*/
1508 if (response_der_len
<= 0)
1509 return SSL_TLSEXT_ERR_NOACK
;
1511 SSL_set_tlsext_status_ocsp_resp(server_ssl
, response_der
, response_der_len
);
1512 tls_in
.ocsp
= OCSP_VFIED
;
1513 return SSL_TLSEXT_ERR_OK
;
1518 time_print(BIO
* bp
, const char * str
, ASN1_GENERALIZEDTIME
* time
)
1520 BIO_printf(bp
, "\t%s: ", str
);
1521 ASN1_GENERALIZEDTIME_print(bp
, time
);
1526 tls_client_stapling_cb(SSL
*s
, void *arg
)
1528 tls_ext_ctx_cb
* cbinfo
= arg
;
1529 const unsigned char * p
;
1531 OCSP_RESPONSE
* rsp
;
1532 OCSP_BASICRESP
* bs
;
1535 DEBUG(D_tls
) debug_printf("Received TLS status response (OCSP stapling):");
1536 len
= SSL_get_tlsext_status_ocsp_resp(s
, &p
);
1539 /* Expect this when we requested ocsp but got none */
1540 if (cbinfo
->u_ocsp
.client
.verify_required
&& LOGGING(tls_cipher
))
1541 log_write(0, LOG_MAIN
, "Received TLS status callback, null content");
1543 DEBUG(D_tls
) debug_printf(" null\n");
1544 return cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1547 if(!(rsp
= d2i_OCSP_RESPONSE(NULL
, &p
, len
)))
1549 tls_out
.ocsp
= OCSP_FAILED
;
1550 if (LOGGING(tls_cipher
))
1551 log_write(0, LOG_MAIN
, "Received TLS cert status response, parse error");
1553 DEBUG(D_tls
) debug_printf(" parse error\n");
1557 if(!(bs
= OCSP_response_get1_basic(rsp
)))
1559 tls_out
.ocsp
= OCSP_FAILED
;
1560 if (LOGGING(tls_cipher
))
1561 log_write(0, LOG_MAIN
, "Received TLS cert status response, error parsing response");
1563 DEBUG(D_tls
) debug_printf(" error parsing response\n");
1564 OCSP_RESPONSE_free(rsp
);
1568 /* We'd check the nonce here if we'd put one in the request. */
1569 /* However that would defeat cacheability on the server so we don't. */
1571 /* This section of code reworked from OpenSSL apps source;
1572 The OpenSSL Project retains copyright:
1573 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1578 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
1580 DEBUG(D_tls
) bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
1582 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1584 /* Use the chain that verified the server cert to verify the stapled info */
1585 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1587 if ((i
= OCSP_basic_verify(bs
, cbinfo
->verify_stack
,
1588 cbinfo
->u_ocsp
.client
.verify_store
, 0)) <= 0)
1590 tls_out
.ocsp
= OCSP_FAILED
;
1591 if (LOGGING(tls_cipher
)) log_write(0, LOG_MAIN
,
1592 "Received TLS cert status response, itself unverifiable: %s",
1593 ERR_reason_error_string(ERR_peek_error()));
1594 BIO_printf(bp
, "OCSP response verify failure\n");
1595 ERR_print_errors(bp
);
1596 OCSP_RESPONSE_print(bp
, rsp
, 0);
1600 BIO_printf(bp
, "OCSP response well-formed and signed OK\n");
1602 /*XXX So we have a good stapled OCSP status. How do we know
1603 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1604 OCSP_resp_find_status() which matches on a cert id, which presumably
1605 we should use. Making an id needs OCSP_cert_id_new(), which takes
1606 issuerName, issuerKey, serialNumber. Are they all in the cert?
1608 For now, carry on blindly accepting the resp. */
1611 OCSP_SINGLERESP
* single
;
1613 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1614 if (OCSP_resp_count(bs
) != 1)
1616 STACK_OF(OCSP_SINGLERESP
) * sresp
= bs
->tbsResponseData
->responses
;
1617 if (sk_OCSP_SINGLERESP_num(sresp
) != 1)
1620 tls_out
.ocsp
= OCSP_FAILED
;
1621 log_write(0, LOG_MAIN
, "OCSP stapling "
1622 "with multiple responses not handled");
1625 single
= OCSP_resp_get0(bs
, 0);
1626 status
= OCSP_single_get0_status(single
, &reason
, &rev
,
1627 &thisupd
, &nextupd
);
1630 DEBUG(D_tls
) time_print(bp
, "This OCSP Update", thisupd
);
1631 DEBUG(D_tls
) if(nextupd
) time_print(bp
, "Next OCSP Update", nextupd
);
1632 if (!OCSP_check_validity(thisupd
, nextupd
,
1633 EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1635 tls_out
.ocsp
= OCSP_FAILED
;
1636 DEBUG(D_tls
) ERR_print_errors(bp
);
1637 log_write(0, LOG_MAIN
, "Server OSCP dates invalid");
1641 DEBUG(D_tls
) BIO_printf(bp
, "Certificate status: %s\n",
1642 OCSP_cert_status_str(status
));
1645 case V_OCSP_CERTSTATUS_GOOD
:
1646 tls_out
.ocsp
= OCSP_VFIED
;
1649 case V_OCSP_CERTSTATUS_REVOKED
:
1650 tls_out
.ocsp
= OCSP_FAILED
;
1651 log_write(0, LOG_MAIN
, "Server certificate revoked%s%s",
1652 reason
!= -1 ? "; reason: " : "",
1653 reason
!= -1 ? OCSP_crl_reason_str(reason
) : "");
1654 DEBUG(D_tls
) time_print(bp
, "Revocation Time", rev
);
1657 tls_out
.ocsp
= OCSP_FAILED
;
1658 log_write(0, LOG_MAIN
,
1659 "Server certificate status unknown, in OCSP stapling");
1664 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1669 OCSP_RESPONSE_free(rsp
);
1672 #endif /*!DISABLE_OCSP*/
1675 /*************************************************
1676 * Initialize for TLS *
1677 *************************************************/
1679 /* Called from both server and client code, to do preliminary initialization
1680 of the library. We allocate and return a context structure.
1683 ctxp returned SSL context
1684 host connected host, if client; NULL if server
1685 dhparam DH parameter file
1686 certificate certificate file
1687 privatekey private key
1688 ocsp_file file of stapling info (server); flag for require ocsp (client)
1689 addr address if client; NULL if server (for some randomness)
1690 cbp place to put allocated callback context
1691 errstr error string pointer
1693 Returns: OK/DEFER/FAIL
1697 tls_init(SSL_CTX
**ctxp
, host_item
*host
, uschar
*dhparam
, uschar
*certificate
,
1699 #ifndef DISABLE_OCSP
1700 uschar
*ocsp_file
, /*XXX stack, in server*/
1702 address_item
*addr
, tls_ext_ctx_cb
** cbp
, uschar
** errstr
)
1707 tls_ext_ctx_cb
* cbinfo
;
1709 cbinfo
= store_malloc(sizeof(tls_ext_ctx_cb
));
1710 cbinfo
->certificate
= certificate
;
1711 cbinfo
->privatekey
= privatekey
;
1712 cbinfo
->is_server
= host
==NULL
;
1713 #ifndef DISABLE_OCSP
1714 cbinfo
->verify_stack
= NULL
;
1717 cbinfo
->u_ocsp
.server
.file
= ocsp_file
;
1718 cbinfo
->u_ocsp
.server
.file_expanded
= NULL
;
1719 cbinfo
->u_ocsp
.server
.response
= NULL
;
1722 cbinfo
->u_ocsp
.client
.verify_store
= NULL
;
1724 cbinfo
->dhparam
= dhparam
;
1725 cbinfo
->server_cipher_list
= NULL
;
1726 cbinfo
->host
= host
;
1727 #ifndef DISABLE_EVENT
1728 cbinfo
->event_action
= NULL
;
1731 #ifdef EXIM_NEED_OPENSSL_INIT
1732 SSL_load_error_strings(); /* basic set up */
1733 OpenSSL_add_ssl_algorithms();
1736 #ifdef EXIM_HAVE_SHA256
1737 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1738 list of available digests. */
1739 EVP_add_digest(EVP_sha256());
1742 /* Create a context.
1743 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1744 negotiation in the different methods; as far as I can tell, the only
1745 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1746 when OpenSSL is built without SSLv2 support.
1747 By disabling with openssl_options, we can let admins re-enable with the
1750 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1751 if (!(ctx
= SSL_CTX_new(host
? TLS_client_method() : TLS_server_method())))
1753 if (!(ctx
= SSL_CTX_new(host
? SSLv23_client_method() : SSLv23_server_method())))
1755 return tls_error(US
"SSL_CTX_new", host
, NULL
, errstr
);
1757 /* It turns out that we need to seed the random number generator this early in
1758 order to get the full complement of ciphers to work. It took me roughly a day
1759 of work to discover this by experiment.
1761 On systems that have /dev/urandom, SSL may automatically seed itself from
1762 there. Otherwise, we have to make something up as best we can. Double check
1768 gettimeofday(&r
.tv
, NULL
);
1771 RAND_seed(US (&r
), sizeof(r
));
1772 RAND_seed(US big_buffer
, big_buffer_size
);
1773 if (addr
!= NULL
) RAND_seed(US addr
, sizeof(addr
));
1776 return tls_error(US
"RAND_status", host
,
1777 US
"unable to seed random number generator", errstr
);
1780 /* Set up the information callback, which outputs if debugging is at a suitable
1783 DEBUG(D_tls
) SSL_CTX_set_info_callback(ctx
, (void (*)())info_callback
);
1784 #ifdef OPENSSL_HAVE_KEYLOG_CB
1785 DEBUG(D_tls
) SSL_CTX_set_keylog_callback(ctx
, (void (*)())keylog_callback
);
1788 /* Automatically re-try reads/writes after renegotiation. */
1789 (void) SSL_CTX_set_mode(ctx
, SSL_MODE_AUTO_RETRY
);
1791 /* Apply administrator-supplied work-arounds.
1792 Historically we applied just one requested option,
1793 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1794 moved to an administrator-controlled list of options to specify and
1795 grandfathered in the first one as the default value for "openssl_options".
1797 No OpenSSL version number checks: the options we accept depend upon the
1798 availability of the option value macros from OpenSSL. */
1800 if (!tls_openssl_options_parse(openssl_options
, &init_options
))
1801 return tls_error(US
"openssl_options parsing failed", host
, NULL
, errstr
);
1805 DEBUG(D_tls
) debug_printf("setting SSL CTX options: %#lx\n", init_options
);
1806 if (!(SSL_CTX_set_options(ctx
, init_options
)))
1807 return tls_error(string_sprintf(
1808 "SSL_CTX_set_option(%#lx)", init_options
), host
, NULL
, errstr
);
1811 DEBUG(D_tls
) debug_printf("no SSL CTX options to set\n");
1813 #ifdef OPENSSL_HAVE_NUM_TICKETS
1814 SSL_CTX_set_num_tickets(ctx
, 0); /* send no TLS1.3 stateful-tickets */
1817 /* We'd like to disable session cache unconditionally, but foolish Outlook
1818 Express clients then give up the first TLS connection and make a second one
1819 (which works). Only when there is an IMAP service on the same machine.
1820 Presumably OE is trying to use the cache for A on B. Leave it enabled for
1821 now, until we work out a decent way of presenting control to the config. It
1822 will never be used because we use a new context every time. */
1824 (void) SSL_CTX_set_session_cache_mode(ctx
, SSL_SESS_CACHE_OFF
);
1827 /* Initialize with DH parameters if supplied */
1828 /* Initialize ECDH temp key parameter selection */
1830 if ( !init_dh(ctx
, dhparam
, host
, errstr
)
1831 || !init_ecdh(ctx
, host
, errstr
)
1835 /* Set up certificate and key (and perhaps OCSP info) */
1837 if ((rc
= tls_expand_session_files(ctx
, cbinfo
, errstr
)) != OK
)
1840 /* If we need to handle SNI or OCSP, do so */
1842 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1843 # ifndef DISABLE_OCSP
1844 if (!(cbinfo
->verify_stack
= sk_X509_new_null()))
1846 DEBUG(D_tls
) debug_printf("failed to create stack for stapling verify\n");
1851 if (!host
) /* server */
1853 # ifndef DISABLE_OCSP
1854 /* We check u_ocsp.server.file, not server.response, because we care about if
1855 the option exists, not what the current expansion might be, as SNI might
1856 change the certificate and OCSP file in use between now and the time the
1857 callback is invoked. */
1858 if (cbinfo
->u_ocsp
.server
.file
)
1860 SSL_CTX_set_tlsext_status_cb(ctx
, tls_server_stapling_cb
);
1861 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
1864 /* We always do this, so that $tls_sni is available even if not used in
1866 SSL_CTX_set_tlsext_servername_callback(ctx
, tls_servername_cb
);
1867 SSL_CTX_set_tlsext_servername_arg(ctx
, cbinfo
);
1869 # ifndef DISABLE_OCSP
1871 if(ocsp_file
) /* wanting stapling */
1873 if (!(cbinfo
->u_ocsp
.client
.verify_store
= X509_STORE_new()))
1875 DEBUG(D_tls
) debug_printf("failed to create store for stapling verify\n");
1878 SSL_CTX_set_tlsext_status_cb(ctx
, tls_client_stapling_cb
);
1879 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
1884 cbinfo
->verify_cert_hostnames
= NULL
;
1886 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1887 /* Set up the RSA callback */
1888 SSL_CTX_set_tmp_rsa_callback(ctx
, rsa_callback
);
1891 /* Finally, set the timeout, and we are done */
1893 SSL_CTX_set_timeout(ctx
, ssl_session_timeout
);
1894 DEBUG(D_tls
) debug_printf("Initialized TLS\n");
1905 /*************************************************
1906 * Get name of cipher in use *
1907 *************************************************/
1910 Argument: pointer to an SSL structure for the connection
1911 buffer to use for answer
1913 pointer to number of bits for cipher
1918 construct_cipher_name(SSL
*ssl
, uschar
*cipherbuf
, int bsize
, int *bits
)
1920 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
1921 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1922 the accessor functions use const in the prototype. */
1924 const uschar
* ver
= CUS
SSL_get_version(ssl
);
1925 const SSL_CIPHER
* c
= (const SSL_CIPHER
*) SSL_get_current_cipher(ssl
);
1927 SSL_CIPHER_get_bits(c
, bits
);
1929 string_format(cipherbuf
, bsize
, "%s:%s:%u", ver
,
1930 SSL_CIPHER_get_name(c
), *bits
);
1932 DEBUG(D_tls
) debug_printf("Cipher: %s\n", cipherbuf
);
1937 peer_cert(SSL
* ssl
, tls_support
* tlsp
, uschar
* peerdn
, unsigned siz
)
1939 /*XXX we might consider a list-of-certs variable for the cert chain.
1940 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1941 in list-handling functions, also consider the difference between the entire
1942 chain and the elements sent by the peer. */
1944 tlsp
->peerdn
= NULL
;
1946 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1947 if (!tlsp
->peercert
)
1948 tlsp
->peercert
= SSL_get_peer_certificate(ssl
);
1949 /* Beware anonymous ciphers which lead to server_cert being NULL */
1951 if (!X509_NAME_oneline(X509_get_subject_name(tlsp
->peercert
), CS peerdn
, siz
))
1952 { DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n"); }
1955 peerdn
[siz
-1] = '\0';
1956 tlsp
->peerdn
= peerdn
; /*XXX a static buffer... */
1964 /*************************************************
1965 * Set up for verifying certificates *
1966 *************************************************/
1968 #ifndef DISABLE_OCSP
1969 /* Load certs from file, return TRUE on success */
1972 chain_from_pem_file(const uschar
* file
, STACK_OF(X509
) * verify_stack
)
1977 while (sk_X509_num(verify_stack
) > 0)
1978 X509_free(sk_X509_pop(verify_stack
));
1980 if (!(bp
= BIO_new_file(CS file
, "r"))) return FALSE
;
1981 while ((x
= PEM_read_bio_X509(bp
, NULL
, 0, NULL
)))
1982 sk_X509_push(verify_stack
, x
);
1990 /* Called by both client and server startup; on the server possibly
1991 repeated after a Server Name Indication.
1994 sctx SSL_CTX* to initialise
1995 certs certs file or NULL
1996 crl CRL file or NULL
1997 host NULL in a server; the remote host in a client
1998 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1999 otherwise passed as FALSE
2000 cert_vfy_cb Callback function for certificate verification
2001 errstr error string pointer
2003 Returns: OK/DEFER/FAIL
2007 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
2008 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*), uschar
** errstr
)
2010 uschar
*expcerts
, *expcrl
;
2012 if (!expand_check(certs
, US
"tls_verify_certificates", &expcerts
, errstr
))
2014 DEBUG(D_tls
) debug_printf("tls_verify_certificates: %s\n", expcerts
);
2016 if (expcerts
&& *expcerts
)
2018 /* Tell the library to use its compiled-in location for the system default
2019 CA bundle. Then add the ones specified in the config, if any. */
2021 if (!SSL_CTX_set_default_verify_paths(sctx
))
2022 return tls_error(US
"SSL_CTX_set_default_verify_paths", host
, NULL
, errstr
);
2024 if (Ustrcmp(expcerts
, "system") != 0)
2026 struct stat statbuf
;
2028 if (Ustat(expcerts
, &statbuf
) < 0)
2030 log_write(0, LOG_MAIN
|LOG_PANIC
,
2031 "failed to stat %s for certificates", expcerts
);
2037 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
2038 { file
= NULL
; dir
= expcerts
; }
2041 file
= expcerts
; dir
= NULL
;
2042 #ifndef DISABLE_OCSP
2043 /* In the server if we will be offering an OCSP proof, load chain from
2044 file for verifying the OCSP proof at load time. */
2047 && statbuf
.st_size
> 0
2048 && server_static_cbinfo
->u_ocsp
.server
.file
2049 && !chain_from_pem_file(file
, server_static_cbinfo
->verify_stack
)
2052 log_write(0, LOG_MAIN
|LOG_PANIC
,
2053 "failed to load cert chain from %s", file
);
2059 /* If a certificate file is empty, the next function fails with an
2060 unhelpful error message. If we skip it, we get the correct behaviour (no
2061 certificates are recognized, but the error message is still misleading (it
2062 says no certificate was supplied). But this is better. */
2064 if ( (!file
|| statbuf
.st_size
> 0)
2065 && !SSL_CTX_load_verify_locations(sctx
, CS file
, CS dir
))
2066 return tls_error(US
"SSL_CTX_load_verify_locations", host
, NULL
, errstr
);
2068 /* Load the list of CAs for which we will accept certs, for sending
2069 to the client. This is only for the one-file tls_verify_certificates
2071 If a list isn't loaded into the server, but some verify locations are set,
2072 the server end appears to make a wildcard request for client certs.
2073 Meanwhile, the client library as default behaviour *ignores* the list
2074 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2075 Because of this, and that the dir variant is likely only used for
2076 the public-CA bundle (not for a private CA), not worth fixing. */
2080 STACK_OF(X509_NAME
) * names
= SSL_load_client_CA_file(CS file
);
2082 SSL_CTX_set_client_CA_list(sctx
, names
);
2083 DEBUG(D_tls
) debug_printf("Added %d certificate authorities.\n",
2084 sk_X509_NAME_num(names
));
2089 /* Handle a certificate revocation list. */
2091 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2093 /* This bit of code is now the version supplied by Lars Mainka. (I have
2094 merely reformatted it into the Exim code style.)
2096 "From here I changed the code to add support for multiple crl's
2097 in pem format in one file or to support hashed directory entries in
2098 pem format instead of a file. This method now uses the library function
2099 X509_STORE_load_locations to add the CRL location to the SSL context.
2100 OpenSSL will then handle the verify against CA certs and CRLs by
2101 itself in the verify callback." */
2103 if (!expand_check(crl
, US
"tls_crl", &expcrl
, errstr
)) return DEFER
;
2104 if (expcrl
&& *expcrl
)
2106 struct stat statbufcrl
;
2107 if (Ustat(expcrl
, &statbufcrl
) < 0)
2109 log_write(0, LOG_MAIN
|LOG_PANIC
,
2110 "failed to stat %s for certificates revocation lists", expcrl
);
2115 /* is it a file or directory? */
2117 X509_STORE
*cvstore
= SSL_CTX_get_cert_store(sctx
);
2118 if ((statbufcrl
.st_mode
& S_IFMT
) == S_IFDIR
)
2122 DEBUG(D_tls
) debug_printf("SSL CRL value is a directory %s\n", dir
);
2128 DEBUG(D_tls
) debug_printf("SSL CRL value is a file %s\n", file
);
2130 if (X509_STORE_load_locations(cvstore
, CS file
, CS dir
) == 0)
2131 return tls_error(US
"X509_STORE_load_locations", host
, NULL
, errstr
);
2133 /* setting the flags to check against the complete crl chain */
2135 X509_STORE_set_flags(cvstore
,
2136 X509_V_FLAG_CRL_CHECK
|X509_V_FLAG_CRL_CHECK_ALL
);
2140 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2142 /* If verification is optional, don't fail if no certificate */
2144 SSL_CTX_set_verify(sctx
,
2145 SSL_VERIFY_PEER
| (optional
? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT
),
2154 /*************************************************
2155 * Start a TLS session in a server *
2156 *************************************************/
2158 /* This is called when Exim is running as a server, after having received
2159 the STARTTLS command. It must respond to that command, and then negotiate
2163 require_ciphers allowed ciphers
2164 errstr pointer to error message
2166 Returns: OK on success
2167 DEFER for errors before the start of the negotiation
2168 FAIL for errors during the negotiation; the server can't
2173 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
2176 uschar
* expciphers
;
2177 tls_ext_ctx_cb
* cbinfo
;
2178 static uschar peerdn
[256];
2179 static uschar cipherbuf
[256];
2181 /* Check for previous activation */
2183 if (tls_in
.active
.sock
>= 0)
2185 tls_error(US
"STARTTLS received after TLS started", NULL
, US
"", errstr
);
2186 smtp_printf("554 Already in TLS\r\n", FALSE
);
2190 /* Initialize the SSL library. If it fails, it will already have logged
2193 rc
= tls_init(&server_ctx
, NULL
, tls_dhparam
, tls_certificate
, tls_privatekey
,
2194 #ifndef DISABLE_OCSP
2195 tls_ocsp_file
, /*XXX stack*/
2197 NULL
, &server_static_cbinfo
, errstr
);
2198 if (rc
!= OK
) return rc
;
2199 cbinfo
= server_static_cbinfo
;
2201 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
, errstr
))
2204 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2205 were historically separated by underscores. So that I can use either form in my
2206 tests, and also for general convenience, we turn underscores into hyphens here.
2208 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2209 for TLS 1.3 . Since we do not call it at present we get the default list:
2210 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2215 uschar
* s
= expciphers
;
2216 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
2217 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2218 if (!SSL_CTX_set_cipher_list(server_ctx
, CS expciphers
))
2219 return tls_error(US
"SSL_CTX_set_cipher_list", NULL
, NULL
, errstr
);
2220 cbinfo
->server_cipher_list
= expciphers
;
2223 /* If this is a host for which certificate verification is mandatory or
2224 optional, set up appropriately. */
2226 tls_in
.certificate_verified
= FALSE
;
2228 tls_in
.dane_verified
= FALSE
;
2230 server_verify_callback_called
= FALSE
;
2232 if (verify_check_host(&tls_verify_hosts
) == OK
)
2234 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
2235 FALSE
, verify_callback_server
, errstr
);
2236 if (rc
!= OK
) return rc
;
2237 server_verify_optional
= FALSE
;
2239 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
2241 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
2242 TRUE
, verify_callback_server
, errstr
);
2243 if (rc
!= OK
) return rc
;
2244 server_verify_optional
= TRUE
;
2247 /* Prepare for new connection */
2249 if (!(server_ssl
= SSL_new(server_ctx
)))
2250 return tls_error(US
"SSL_new", NULL
, NULL
, errstr
);
2252 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2254 * With the SSL_clear(), we get strange interoperability bugs with
2255 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2256 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2258 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2259 * session shutdown. In this case, we have a brand new object and there's no
2260 * obvious reason to immediately clear it. I'm guessing that this was
2261 * originally added because of incomplete initialisation which the clear fixed,
2262 * in some historic release.
2265 /* Set context and tell client to go ahead, except in the case of TLS startup
2266 on connection, where outputting anything now upsets the clients and tends to
2267 make them disconnect. We need to have an explicit fflush() here, to force out
2268 the response. Other smtp_printf() calls do not need it, because in non-TLS
2269 mode, the fflush() happens when smtp_getc() is called. */
2271 SSL_set_session_id_context(server_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
2272 if (!tls_in
.on_connect
)
2274 smtp_printf("220 TLS go ahead\r\n", FALSE
);
2278 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2279 that the OpenSSL library doesn't. */
2281 SSL_set_wfd(server_ssl
, fileno(smtp_out
));
2282 SSL_set_rfd(server_ssl
, fileno(smtp_in
));
2283 SSL_set_accept_state(server_ssl
);
2285 DEBUG(D_tls
) debug_printf("Calling SSL_accept\n");
2287 sigalrm_seen
= FALSE
;
2288 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2289 rc
= SSL_accept(server_ssl
);
2294 (void) tls_error(US
"SSL_accept", NULL
, sigalrm_seen
? US
"timed out" : NULL
, errstr
);
2298 DEBUG(D_tls
) debug_printf("SSL_accept was successful\n");
2299 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2300 anon-authentication ciphersuite negociated. */
2302 /* TLS has been set up. Adjust the input functions to read via TLS,
2303 and initialize things. */
2305 peer_cert(server_ssl
, &tls_in
, peerdn
, sizeof(peerdn
));
2307 construct_cipher_name(server_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_in
.bits
);
2308 tls_in
.cipher
= cipherbuf
;
2313 if (SSL_get_shared_ciphers(server_ssl
, CS buf
, sizeof(buf
)) != NULL
)
2314 debug_printf("Shared ciphers: %s\n", buf
);
2317 /* Record the certificate we presented */
2319 X509
* crt
= SSL_get_certificate(server_ssl
);
2320 tls_in
.ourcert
= crt
? X509_dup(crt
) : NULL
;
2323 /* Only used by the server-side tls (tls_in), including tls_getc.
2324 Client-side (tls_out) reads (seem to?) go via
2325 smtp_read_response()/ip_recv().
2326 Hence no need to duplicate for _in and _out.
2328 if (!ssl_xfer_buffer
) ssl_xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2329 ssl_xfer_buffer_lwm
= ssl_xfer_buffer_hwm
= 0;
2330 ssl_xfer_eof
= ssl_xfer_error
= FALSE
;
2332 receive_getc
= tls_getc
;
2333 receive_getbuf
= tls_getbuf
;
2334 receive_get_cache
= tls_get_cache
;
2335 receive_ungetc
= tls_ungetc
;
2336 receive_feof
= tls_feof
;
2337 receive_ferror
= tls_ferror
;
2338 receive_smtp_buffered
= tls_smtp_buffered
;
2340 tls_in
.active
.sock
= fileno(smtp_out
);
2341 tls_in
.active
.tls_ctx
= NULL
; /* not using explicit ctx for server-side */
2349 tls_client_basic_ctx_init(SSL_CTX
* ctx
,
2350 host_item
* host
, smtp_transport_options_block
* ob
, tls_ext_ctx_cb
* cbinfo
,
2354 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2355 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2356 the specified host patterns if one of them is defined */
2358 if ( ( !ob
->tls_verify_hosts
2359 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2361 || verify_check_given_host(CUSS
&ob
->tls_verify_hosts
, host
) == OK
2363 client_verify_optional
= FALSE
;
2364 else if (verify_check_given_host(CUSS
&ob
->tls_try_verify_hosts
, host
) == OK
)
2365 client_verify_optional
= TRUE
;
2369 if ((rc
= setup_certs(ctx
, ob
->tls_verify_certificates
,
2370 ob
->tls_crl
, host
, client_verify_optional
, verify_callback_client
,
2374 if (verify_check_given_host(CUSS
&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2376 cbinfo
->verify_cert_hostnames
=
2378 string_domain_utf8_to_alabel(host
->name
, NULL
);
2382 DEBUG(D_tls
) debug_printf("Cert hostname to check: \"%s\"\n",
2383 cbinfo
->verify_cert_hostnames
);
2391 dane_tlsa_load(SSL
* ssl
, host_item
* host
, dns_answer
* dnsa
, uschar
** errstr
)
2394 const char * hostnames
[2] = { CS host
->name
, NULL
};
2397 if (DANESSL_init(ssl
, NULL
, hostnames
) != 1)
2398 return tls_error(US
"hostnames load", host
, NULL
, errstr
);
2400 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2401 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2402 ) if (rr
->type
== T_TLSA
&& rr
->size
> 3)
2404 const uschar
* p
= rr
->data
;
2405 uint8_t usage
, selector
, mtype
;
2406 const char * mdname
;
2410 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2411 if (usage
!= 2 && usage
!= 3) continue;
2418 default: continue; /* Only match-types 0, 1, 2 are supported */
2419 case 0: mdname
= NULL
; break;
2420 case 1: mdname
= "sha256"; break;
2421 case 2: mdname
= "sha512"; break;
2425 switch (DANESSL_add_tlsa(ssl
, usage
, selector
, mdname
, p
, rr
->size
- 3))
2428 return tls_error(US
"tlsa load", host
, NULL
, errstr
);
2429 case 0: /* action not taken */
2433 tls_out
.tlsa_usage
|= 1<<usage
;
2439 log_write(0, LOG_MAIN
, "DANE error: No usable TLSA records");
2442 #endif /*SUPPORT_DANE*/
2446 /*************************************************
2447 * Start a TLS session in a client *
2448 *************************************************/
2450 /* Called from the smtp transport after STARTTLS has been accepted.
2453 fd the fd of the connection
2454 host connected host (for messages and option-tests)
2455 addr the first address (for some randomness; can be NULL)
2456 tb transport (always smtp)
2457 tlsa_dnsa tlsa lookup, if DANE, else null
2458 tlsp record details of channel configuration here; must be non-NULL
2459 errstr error string pointer
2461 Returns: Pointer to TLS session context, or NULL on error
2465 tls_client_start(int fd
, host_item
*host
, address_item
*addr
,
2466 transport_instance
* tb
,
2468 dns_answer
* tlsa_dnsa
,
2470 tls_support
* tlsp
, uschar
** errstr
)
2472 smtp_transport_options_block
* ob
= tb
2473 ? (smtp_transport_options_block
*)tb
->options_block
2474 : &smtp_transport_option_defaults
;
2475 exim_openssl_client_tls_ctx
* exim_client_ctx
;
2476 static uschar peerdn
[256];
2477 uschar
* expciphers
;
2479 static uschar cipherbuf
[256];
2481 #ifndef DISABLE_OCSP
2482 BOOL request_ocsp
= FALSE
;
2483 BOOL require_ocsp
= FALSE
;
2487 store_pool
= POOL_PERM
;
2488 exim_client_ctx
= store_get(sizeof(exim_openssl_client_tls_ctx
));
2492 tlsp
->tlsa_usage
= 0;
2495 #ifndef DISABLE_OCSP
2497 # ifdef SUPPORT_DANE
2499 && ob
->hosts_request_ocsp
[0] == '*'
2500 && ob
->hosts_request_ocsp
[1] == '\0'
2503 /* Unchanged from default. Use a safer one under DANE */
2504 request_ocsp
= TRUE
;
2505 ob
->hosts_request_ocsp
= US
"${if or { {= {0}{$tls_out_tlsa_usage}} "
2506 " {= {4}{$tls_out_tlsa_usage}} } "
2512 verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
))
2513 request_ocsp
= TRUE
;
2515 # ifdef SUPPORT_DANE
2519 verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2523 rc
= tls_init(&exim_client_ctx
->ctx
, host
, NULL
,
2524 ob
->tls_certificate
, ob
->tls_privatekey
,
2525 #ifndef DISABLE_OCSP
2526 (void *)(long)request_ocsp
,
2528 addr
, &client_static_cbinfo
, errstr
);
2529 if (rc
!= OK
) return NULL
;
2531 tlsp
->certificate_verified
= FALSE
;
2532 client_verify_callback_called
= FALSE
;
2538 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2539 other failures should be treated as problems. */
2540 if (ob
->dane_require_tls_ciphers
&&
2541 !expand_check(ob
->dane_require_tls_ciphers
, US
"dane_require_tls_ciphers",
2542 &expciphers
, errstr
))
2544 if (expciphers
&& *expciphers
== '\0')
2549 !expand_check(ob
->tls_require_ciphers
, US
"tls_require_ciphers",
2550 &expciphers
, errstr
))
2553 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2554 are separated by underscores. So that I can use either form in my tests, and
2555 also for general convenience, we turn underscores into hyphens here. */
2559 uschar
*s
= expciphers
;
2560 while (*s
) { if (*s
== '_') *s
= '-'; s
++; }
2561 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2562 if (!SSL_CTX_set_cipher_list(exim_client_ctx
->ctx
, CS expciphers
))
2564 tls_error(US
"SSL_CTX_set_cipher_list", host
, NULL
, errstr
);
2572 SSL_CTX_set_verify(exim_client_ctx
->ctx
,
2573 SSL_VERIFY_PEER
| SSL_VERIFY_FAIL_IF_NO_PEER_CERT
,
2574 verify_callback_client_dane
);
2576 if (!DANESSL_library_init())
2578 tls_error(US
"library init", host
, NULL
, errstr
);
2581 if (DANESSL_CTX_init(exim_client_ctx
->ctx
) <= 0)
2583 tls_error(US
"context init", host
, NULL
, errstr
);
2591 if (tls_client_basic_ctx_init(exim_client_ctx
->ctx
, host
, ob
,
2592 client_static_cbinfo
, errstr
) != OK
)
2595 if (!(exim_client_ctx
->ssl
= SSL_new(exim_client_ctx
->ctx
)))
2597 tls_error(US
"SSL_new", host
, NULL
, errstr
);
2600 SSL_set_session_id_context(exim_client_ctx
->ssl
, sid_ctx
, Ustrlen(sid_ctx
));
2601 SSL_set_fd(exim_client_ctx
->ssl
, fd
);
2602 SSL_set_connect_state(exim_client_ctx
->ssl
);
2606 if (!expand_check(ob
->tls_sni
, US
"tls_sni", &tlsp
->sni
, errstr
))
2610 DEBUG(D_tls
) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2612 else if (!Ustrlen(tlsp
->sni
))
2616 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2617 DEBUG(D_tls
) debug_printf("Setting TLS SNI \"%s\"\n", tlsp
->sni
);
2618 SSL_set_tlsext_host_name(exim_client_ctx
->ssl
, tlsp
->sni
);
2620 log_write(0, LOG_MAIN
, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2628 if (dane_tlsa_load(exim_client_ctx
->ssl
, host
, tlsa_dnsa
, errstr
) != OK
)
2632 #ifndef DISABLE_OCSP
2633 /* Request certificate status at connection-time. If the server
2634 does OCSP stapling we will get the callback (set in tls_init()) */
2635 # ifdef SUPPORT_DANE
2639 if ( ((s
= ob
->hosts_require_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
2640 || ((s
= ob
->hosts_request_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
2642 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2643 this means we avoid the OCSP request, we wasted the setup
2644 cost in tls_init(). */
2645 require_ocsp
= verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
;
2646 request_ocsp
= require_ocsp
2647 || verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2654 SSL_set_tlsext_status_type(exim_client_ctx
->ssl
, TLSEXT_STATUSTYPE_ocsp
);
2655 client_static_cbinfo
->u_ocsp
.client
.verify_required
= require_ocsp
;
2656 tlsp
->ocsp
= OCSP_NOT_RESP
;
2660 #ifndef DISABLE_EVENT
2661 client_static_cbinfo
->event_action
= tb
? tb
->event_action
: NULL
;
2664 /* There doesn't seem to be a built-in timeout on connection. */
2666 DEBUG(D_tls
) debug_printf("Calling SSL_connect\n");
2667 sigalrm_seen
= FALSE
;
2668 ALARM(ob
->command_timeout
);
2669 rc
= SSL_connect(exim_client_ctx
->ssl
);
2674 DANESSL_cleanup(exim_client_ctx
->ssl
);
2679 tls_error(US
"SSL_connect", host
, sigalrm_seen
? US
"timed out" : NULL
, errstr
);
2683 DEBUG(D_tls
) debug_printf("SSL_connect succeeded\n");
2685 peer_cert(exim_client_ctx
->ssl
, tlsp
, peerdn
, sizeof(peerdn
));
2687 construct_cipher_name(exim_client_ctx
->ssl
, cipherbuf
, sizeof(cipherbuf
), &tlsp
->bits
);
2688 tlsp
->cipher
= cipherbuf
;
2690 /* Record the certificate we presented */
2692 X509
* crt
= SSL_get_certificate(exim_client_ctx
->ssl
);
2693 tlsp
->ourcert
= crt
? X509_dup(crt
) : NULL
;
2696 tlsp
->active
.sock
= fd
;
2697 tlsp
->active
.tls_ctx
= exim_client_ctx
;
2698 return exim_client_ctx
;
2706 tls_refill(unsigned lim
)
2711 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl
,
2712 ssl_xfer_buffer
, ssl_xfer_buffer_size
);
2714 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2715 inbytes
= SSL_read(server_ssl
, CS ssl_xfer_buffer
,
2716 MIN(ssl_xfer_buffer_size
, lim
));
2717 error
= SSL_get_error(server_ssl
, inbytes
);
2718 if (smtp_receive_timeout
> 0) ALARM_CLR(0);
2720 if (had_command_timeout
) /* set by signal handler */
2721 smtp_command_timeout_exit(); /* does not return */
2722 if (had_command_sigterm
)
2723 smtp_command_sigterm_exit();
2724 if (had_data_timeout
)
2725 smtp_data_timeout_exit();
2726 if (had_data_sigint
)
2727 smtp_data_sigint_exit();
2729 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2730 closed down, not that the socket itself has been closed down. Revert to
2731 non-SSL handling. */
2735 case SSL_ERROR_NONE
:
2738 case SSL_ERROR_ZERO_RETURN
:
2739 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2741 receive_getc
= smtp_getc
;
2742 receive_getbuf
= smtp_getbuf
;
2743 receive_get_cache
= smtp_get_cache
;
2744 receive_ungetc
= smtp_ungetc
;
2745 receive_feof
= smtp_feof
;
2746 receive_ferror
= smtp_ferror
;
2747 receive_smtp_buffered
= smtp_buffered
;
2749 if (SSL_get_shutdown(server_ssl
) == SSL_RECEIVED_SHUTDOWN
)
2750 SSL_shutdown(server_ssl
);
2752 #ifndef DISABLE_OCSP
2753 sk_X509_pop_free(server_static_cbinfo
->verify_stack
, X509_free
);
2754 server_static_cbinfo
->verify_stack
= NULL
;
2756 SSL_free(server_ssl
);
2757 SSL_CTX_free(server_ctx
);
2760 tls_in
.active
.sock
= -1;
2761 tls_in
.active
.tls_ctx
= NULL
;
2763 tls_in
.cipher
= NULL
;
2764 tls_in
.peerdn
= NULL
;
2769 /* Handle genuine errors */
2771 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
2772 log_write(0, LOG_MAIN
, "TLS error (SSL_read): %s", ssl_errstring
);
2773 ssl_xfer_error
= TRUE
;
2777 DEBUG(D_tls
) debug_printf("Got SSL error %d\n", error
);
2778 DEBUG(D_tls
) if (error
== SSL_ERROR_SYSCALL
)
2779 debug_printf(" - syscall %s\n", strerror(errno
));
2780 ssl_xfer_error
= TRUE
;
2784 #ifndef DISABLE_DKIM
2785 dkim_exim_verify_feed(ssl_xfer_buffer
, inbytes
);
2787 ssl_xfer_buffer_hwm
= inbytes
;
2788 ssl_xfer_buffer_lwm
= 0;
2793 /*************************************************
2794 * TLS version of getc *
2795 *************************************************/
2797 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2798 it refills the buffer via the SSL reading function.
2800 Arguments: lim Maximum amount to read/buffer
2801 Returns: the next character or EOF
2803 Only used by the server-side TLS.
2807 tls_getc(unsigned lim
)
2809 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
2810 if (!tls_refill(lim
))
2811 return ssl_xfer_error
? EOF
: smtp_getc(lim
);
2813 /* Something in the buffer; return next uschar */
2815 return ssl_xfer_buffer
[ssl_xfer_buffer_lwm
++];
2819 tls_getbuf(unsigned * len
)
2824 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
2825 if (!tls_refill(*len
))
2827 if (!ssl_xfer_error
) return smtp_getbuf(len
);
2832 if ((size
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
) > *len
)
2834 buf
= &ssl_xfer_buffer
[ssl_xfer_buffer_lwm
];
2835 ssl_xfer_buffer_lwm
+= size
;
2844 #ifndef DISABLE_DKIM
2845 int n
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
;
2847 dkim_exim_verify_feed(ssl_xfer_buffer
+ssl_xfer_buffer_lwm
, n
);
2853 tls_could_read(void)
2855 return ssl_xfer_buffer_lwm
< ssl_xfer_buffer_hwm
|| SSL_pending(server_ssl
) > 0;
2859 /*************************************************
2860 * Read bytes from TLS channel *
2861 *************************************************/
2865 ct_ctx client context pointer, or NULL for the one global server context
2869 Returns: the number of bytes read
2870 -1 after a failed read, including EOF
2872 Only used by the client-side TLS.
2876 tls_read(void * ct_ctx
, uschar
*buff
, size_t len
)
2878 SSL
* ssl
= ct_ctx
? ((exim_openssl_client_tls_ctx
*)ct_ctx
)->ssl
: server_ssl
;
2882 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl
,
2883 buff
, (unsigned int)len
);
2885 inbytes
= SSL_read(ssl
, CS buff
, len
);
2886 error
= SSL_get_error(ssl
, inbytes
);
2888 if (error
== SSL_ERROR_ZERO_RETURN
)
2890 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2893 else if (error
!= SSL_ERROR_NONE
)
2903 /*************************************************
2904 * Write bytes down TLS channel *
2905 *************************************************/
2909 ct_ctx client context pointer, or NULL for the one global server context
2912 more further data expected soon
2914 Returns: the number of bytes after a successful write,
2915 -1 after a failed write
2917 Used by both server-side and client-side TLS.
2921 tls_write(void * ct_ctx
, const uschar
*buff
, size_t len
, BOOL more
)
2924 int outbytes
, error
;
2925 SSL
* ssl
= ct_ctx
? ((exim_openssl_client_tls_ctx
*)ct_ctx
)->ssl
: server_ssl
;
2926 static gstring
* corked
= NULL
;
2928 DEBUG(D_tls
) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__
,
2929 buff
, (unsigned long)len
, more
? ", more" : "");
2931 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
2932 "more" is notified. This hack is only ok if small amounts are involved AND only
2933 one stream does it, in one context (i.e. no store reset). Currently it is used
2934 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */
2935 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
2936 a store reset there, so use POOL_PERM. */
2937 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
2939 if ((more
|| corked
))
2941 #ifdef EXPERIMENTAL_PIPE_CONNECT
2942 int save_pool
= store_pool
;
2943 store_pool
= POOL_PERM
;
2946 corked
= string_catn(corked
, buff
, len
);
2948 #ifdef EXPERIMENTAL_PIPE_CONNECT
2949 store_pool
= save_pool
;
2954 buff
= CUS corked
->s
;
2959 for (int left
= len
; left
> 0;)
2961 DEBUG(D_tls
) debug_printf("SSL_write(%p, %p, %d)\n", ssl
, buff
, left
);
2962 outbytes
= SSL_write(ssl
, CS buff
, left
);
2963 error
= SSL_get_error(ssl
, outbytes
);
2964 DEBUG(D_tls
) debug_printf("outbytes=%d error=%d\n", outbytes
, error
);
2968 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
2969 log_write(0, LOG_MAIN
, "TLS error (SSL_write): %s", ssl_errstring
);
2972 case SSL_ERROR_NONE
:
2977 case SSL_ERROR_ZERO_RETURN
:
2978 log_write(0, LOG_MAIN
, "SSL channel closed on write");
2981 case SSL_ERROR_SYSCALL
:
2982 log_write(0, LOG_MAIN
, "SSL_write: (from %s) syscall: %s",
2983 sender_fullhost
? sender_fullhost
: US
"<unknown>",
2988 log_write(0, LOG_MAIN
, "SSL_write error %d", error
);
2997 /*************************************************
2998 * Close down a TLS session *
2999 *************************************************/
3001 /* This is also called from within a delivery subprocess forked from the
3002 daemon, to shut down the TLS library, without actually doing a shutdown (which
3003 would tamper with the SSL session in the parent process).
3006 ct_ctx client TLS context pointer, or NULL for the one global server context
3007 shutdown 1 if TLS close-alert is to be sent,
3008 2 if also response to be waited for
3012 Used by both server-side and client-side TLS.
3016 tls_close(void * ct_ctx
, int shutdown
)
3018 exim_openssl_client_tls_ctx
* o_ctx
= ct_ctx
;
3019 SSL_CTX
**ctxp
= o_ctx
? &o_ctx
->ctx
: &server_ctx
;
3020 SSL
**sslp
= o_ctx
? &o_ctx
->ssl
: &server_ssl
;
3021 int *fdp
= o_ctx
? &tls_out
.active
.sock
: &tls_in
.active
.sock
;
3023 if (*fdp
< 0) return; /* TLS was not active */
3028 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS%s\n",
3029 shutdown
> 1 ? " (with response-wait)" : "");
3031 if ( (rc
= SSL_shutdown(*sslp
)) == 0 /* send "close notify" alert */
3035 rc
= SSL_shutdown(*sslp
); /* wait for response */
3039 if (rc
< 0) DEBUG(D_tls
)
3041 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3042 debug_printf("SSL_shutdown: %s\n", ssl_errstring
);
3046 #ifndef DISABLE_OCSP
3047 if (!o_ctx
) /* server side */
3049 sk_X509_pop_free(server_static_cbinfo
->verify_stack
, X509_free
);
3050 server_static_cbinfo
->verify_stack
= NULL
;
3054 SSL_CTX_free(*ctxp
);
3064 /*************************************************
3065 * Let tls_require_ciphers be checked at startup *
3066 *************************************************/
3068 /* The tls_require_ciphers option, if set, must be something which the
3071 Returns: NULL on success, or error message
3075 tls_validate_require_cipher(void)
3078 uschar
*s
, *expciphers
, *err
;
3080 /* this duplicates from tls_init(), we need a better "init just global
3081 state, for no specific purpose" singleton function of our own */
3083 #ifdef EXIM_NEED_OPENSSL_INIT
3084 SSL_load_error_strings();
3085 OpenSSL_add_ssl_algorithms();
3087 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
3088 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
3089 list of available digests. */
3090 EVP_add_digest(EVP_sha256());
3093 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
3096 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
3098 return US
"failed to expand tls_require_ciphers";
3100 if (!(expciphers
&& *expciphers
))
3103 /* normalisation ripped from above */
3105 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
3109 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3110 if (!(ctx
= SSL_CTX_new(TLS_server_method())))
3112 if (!(ctx
= SSL_CTX_new(SSLv23_server_method())))
3115 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3116 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring
);
3120 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
3122 if (!SSL_CTX_set_cipher_list(ctx
, CS expciphers
))
3124 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3125 err
= string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3126 expciphers
, ssl_errstring
);
3137 /*************************************************
3138 * Report the library versions. *
3139 *************************************************/
3141 /* There have historically been some issues with binary compatibility in
3142 OpenSSL libraries; if Exim (like many other applications) is built against
3143 one version of OpenSSL but the run-time linker picks up another version,
3144 it can result in serious failures, including crashing with a SIGSEGV. So
3145 report the version found by the compiler and the run-time version.
3147 Note: some OS vendors backport security fixes without changing the version
3148 number/string, and the version date remains unchanged. The _build_ date
3149 will change, so we can more usefully assist with version diagnosis by also
3150 reporting the build date.
3152 Arguments: a FILE* to print the results to
3157 tls_version_report(FILE *f
)
3159 fprintf(f
, "Library version: OpenSSL: Compile: %s\n"
3162 OPENSSL_VERSION_TEXT
,
3163 SSLeay_version(SSLEAY_VERSION
),
3164 SSLeay_version(SSLEAY_BUILT_ON
));
3165 /* third line is 38 characters for the %s and the line is 73 chars long;
3166 the OpenSSL output includes a "built on: " prefix already. */
3172 /*************************************************
3173 * Random number generation *
3174 *************************************************/
3176 /* Pseudo-random number generation. The result is not expected to be
3177 cryptographically strong but not so weak that someone will shoot themselves
3178 in the foot using it as a nonce in input in some email header scheme or
3179 whatever weirdness they'll twist this into. The result should handle fork()
3180 and avoid repeating sequences. OpenSSL handles that for us.
3184 Returns a random number in range [0, max-1]
3188 vaguely_random_number(int max
)
3192 static pid_t pidlast
= 0;
3194 uschar smallbuf
[sizeof(r
)];
3200 if (pidnow
!= pidlast
)
3202 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3203 is unique for each thread", this doesn't apparently apply across processes,
3204 so our own warning from vaguely_random_number_fallback() applies here too.
3205 Fix per PostgreSQL. */
3211 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3215 gettimeofday(&r
.tv
, NULL
);
3218 RAND_seed(US (&r
), sizeof(r
));
3220 /* We're after pseudo-random, not random; if we still don't have enough data
3221 in the internal PRNG then our options are limited. We could sleep and hope
3222 for entropy to come along (prayer technique) but if the system is so depleted
3223 in the first place then something is likely to just keep taking it. Instead,
3224 we'll just take whatever little bit of pseudo-random we can still manage to
3227 needed_len
= sizeof(r
);
3228 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3229 asked for a number less than 10. */
3230 for (r
= max
, i
= 0; r
; ++i
)
3236 #ifdef EXIM_HAVE_RAND_PSEUDO
3237 /* We do not care if crypto-strong */
3238 i
= RAND_pseudo_bytes(smallbuf
, needed_len
);
3240 i
= RAND_bytes(smallbuf
, needed_len
);
3246 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3247 return vaguely_random_number_fallback(max
);
3251 for (uschar
* p
= smallbuf
; needed_len
; --needed_len
, ++p
)
3254 /* We don't particularly care about weighted results; if someone wants
3255 smooth distribution and cares enough then they should submit a patch then. */
3262 /*************************************************
3263 * OpenSSL option parse *
3264 *************************************************/
3266 /* Parse one option for tls_openssl_options_parse below
3269 name one option name
3270 value place to store a value for it
3271 Returns success or failure in parsing
3277 tls_openssl_one_option_parse(uschar
*name
, long *value
)
3280 int last
= exim_openssl_options_size
;
3281 while (last
> first
)
3283 int middle
= (first
+ last
)/2;
3284 int c
= Ustrcmp(name
, exim_openssl_options
[middle
].name
);
3287 *value
= exim_openssl_options
[middle
].value
;
3301 /*************************************************
3302 * OpenSSL option parsing logic *
3303 *************************************************/
3305 /* OpenSSL has a number of compatibility options which an administrator might
3306 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3307 we look like log_selector.
3310 option_spec the administrator-supplied string of options
3311 results ptr to long storage for the options bitmap
3312 Returns success or failure
3316 tls_openssl_options_parse(uschar
*option_spec
, long *results
)
3321 BOOL adding
, item_parsed
;
3323 result
= SSL_OP_NO_TICKET
;
3324 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3325 * from default because it increases BEAST susceptibility. */
3326 #ifdef SSL_OP_NO_SSLv2
3327 result
|= SSL_OP_NO_SSLv2
;
3329 #ifdef SSL_OP_SINGLE_DH_USE
3330 result
|= SSL_OP_SINGLE_DH_USE
;
3339 for (uschar
* s
= option_spec
; *s
!= '\0'; /**/)
3341 while (isspace(*s
)) ++s
;
3344 if (*s
!= '+' && *s
!= '-')
3346 DEBUG(D_tls
) debug_printf("malformed openssl option setting: "
3347 "+ or - expected but found \"%s\"\n", s
);
3350 adding
= *s
++ == '+';
3351 for (end
= s
; (*end
!= '\0') && !isspace(*end
); ++end
) /**/ ;
3354 item_parsed
= tls_openssl_one_option_parse(s
, &item
);
3358 DEBUG(D_tls
) debug_printf("openssl option setting unrecognised: \"%s\"\n", s
);
3361 DEBUG(D_tls
) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
3362 adding
? "adding" : "removing", result
, item
, s
);
3374 #endif /*!MACRO_PREDEF*/
3377 /* End of tls-openssl.c */