1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
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
73 # define EXIM_HAVE_OPENSSL_KEYLOG
74 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
75 # define EXIM_HAVE_SESSION_TICKET
76 # define EXIM_HAVE_OPESSL_TRACE
78 # define EXIM_NEED_OPENSSL_INIT
80 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
81 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
82 # define EXIM_HAVE_OPENSSL_CHECKHOST
86 #if !defined(LIBRESSL_VERSION_NUMBER) \
87 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
88 # if !defined(OPENSSL_NO_ECDH)
89 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
90 # define EXIM_HAVE_ECDH
92 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
93 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
98 #ifndef LIBRESSL_VERSION_NUMBER
99 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
100 # define OPENSSL_HAVE_KEYLOG_CB
101 # define OPENSSL_HAVE_NUM_TICKETS
102 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
106 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
107 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
108 # define DISABLE_OCSP
111 #ifdef EXPERIMENTAL_TLS_RESUME
112 # if OPENSSL_VERSION_NUMBER < 0x0101010L
113 # error OpenSSL version too old for session-resumption
117 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
118 # include <openssl/x509v3.h>
121 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
122 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
123 # define SSL_CIPHER_get_id(c) (c->id)
125 # ifndef MACRO_PREDEF
126 # include "tls-cipher-stdname.c"
130 /*************************************************
131 * OpenSSL option parse *
132 *************************************************/
134 typedef struct exim_openssl_option
{
137 } exim_openssl_option
;
138 /* We could use a macro to expand, but we need the ifdef and not all the
139 options document which version they were introduced in. Policylet: include
140 all options unless explicitly for DTLS, let the administrator choose which
143 This list is current as of:
145 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
146 Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev
148 static exim_openssl_option exim_openssl_options
[] = {
149 /* KEEP SORTED ALPHABETICALLY! */
151 { US
"all", SSL_OP_ALL
},
153 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
154 { US
"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
},
156 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
157 { US
"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE
},
159 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
160 { US
"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
},
162 #ifdef SSL_OP_EPHEMERAL_RSA
163 { US
"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA
},
165 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
166 { US
"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT
},
168 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
169 { US
"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
},
171 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
172 { US
"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG
},
174 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
175 { US
"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING
},
177 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
178 { US
"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG
},
180 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
181 { US
"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
},
183 #ifdef SSL_OP_NO_COMPRESSION
184 { US
"no_compression", SSL_OP_NO_COMPRESSION
},
186 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
187 { US
"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
},
189 #ifdef SSL_OP_NO_SSLv2
190 { US
"no_sslv2", SSL_OP_NO_SSLv2
},
192 #ifdef SSL_OP_NO_SSLv3
193 { US
"no_sslv3", SSL_OP_NO_SSLv3
},
195 #ifdef SSL_OP_NO_TICKET
196 { US
"no_ticket", SSL_OP_NO_TICKET
},
198 #ifdef SSL_OP_NO_TLSv1
199 { US
"no_tlsv1", SSL_OP_NO_TLSv1
},
201 #ifdef SSL_OP_NO_TLSv1_1
202 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
203 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
204 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
206 { US
"no_tlsv1_1", SSL_OP_NO_TLSv1_1
},
209 #ifdef SSL_OP_NO_TLSv1_2
210 { US
"no_tlsv1_2", SSL_OP_NO_TLSv1_2
},
212 #ifdef SSL_OP_NO_TLSv1_3
213 { US
"no_tlsv1_3", SSL_OP_NO_TLSv1_3
},
215 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
216 { US
"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG
},
218 #ifdef SSL_OP_SINGLE_DH_USE
219 { US
"single_dh_use", SSL_OP_SINGLE_DH_USE
},
221 #ifdef SSL_OP_SINGLE_ECDH_USE
222 { US
"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE
},
224 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
225 { US
"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG
},
227 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
228 { US
"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
},
230 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
231 { US
"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG
},
233 #ifdef SSL_OP_TLS_D5_BUG
234 { US
"tls_d5_bug", SSL_OP_TLS_D5_BUG
},
236 #ifdef SSL_OP_TLS_ROLLBACK_BUG
237 { US
"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG
},
242 static int exim_openssl_options_size
= nelem(exim_openssl_options
);
251 for (struct exim_openssl_option
* o
= exim_openssl_options
;
252 o
< exim_openssl_options
+ nelem(exim_openssl_options
); o
++)
254 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
255 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
257 spf(buf
, sizeof(buf
), US
"_OPT_OPENSSL_%T_X", o
->name
);
258 builtin_macro_create(buf
);
261 # ifdef EXPERIMENTAL_TLS_RESUME
262 builtin_macro_create_var(US
"_RESUME_DECODE", RESUME_DECODE_STRING
);
267 /******************************************************************************/
269 /* Structure for collecting random data for seeding. */
271 typedef struct randstuff
{
276 /* Local static variables */
278 static BOOL client_verify_callback_called
= FALSE
;
279 static BOOL server_verify_callback_called
= FALSE
;
280 static const uschar
*sid_ctx
= US
"exim";
282 /* We have three different contexts to care about.
284 Simple case: client, `client_ctx`
285 As a client, we can be doing a callout or cut-through delivery while receiving
286 a message. So we have a client context, which should have options initialised
287 from the SMTP Transport. We may also concurrently want to make TLS connections
288 to utility daemons, so client-contexts are allocated and passed around in call
289 args rather than using a gobal.
292 There are two cases: with and without ServerNameIndication from the client.
293 Given TLS SNI, we can be using different keys, certs and various other
294 configuration settings, because they're re-expanded with $tls_sni set. This
295 allows vhosting with TLS. This SNI is sent in the handshake.
296 A client might not send SNI, so we need a fallback, and an initial setup too.
297 So as a server, we start out using `server_ctx`.
298 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
299 `server_sni` from `server_ctx` and then initialise settings by re-expanding
307 } exim_openssl_client_tls_ctx
;
309 static SSL_CTX
*server_ctx
= NULL
;
310 static SSL
*server_ssl
= NULL
;
312 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
313 static SSL_CTX
*server_sni
= NULL
;
316 static char ssl_errstring
[256];
318 static int ssl_session_timeout
= 7200; /* Two hours */
319 static BOOL client_verify_optional
= FALSE
;
320 static BOOL server_verify_optional
= FALSE
;
322 static BOOL reexpand_tls_files_for_sni
= FALSE
;
325 typedef struct tls_ext_ctx_cb
{
331 STACK_OF(X509
) *verify_stack
; /* chain for verifying the proof */
335 uschar
*file_expanded
;
336 OCSP_RESPONSE
*response
;
339 X509_STORE
*verify_store
; /* non-null if status requested */
340 BOOL verify_required
;
345 /* these are cached from first expand */
346 uschar
*server_cipher_list
;
347 /* only passed down to tls_error: */
349 const uschar
* verify_cert_hostnames
;
350 #ifndef DISABLE_EVENT
351 uschar
* event_action
;
355 /* should figure out a cleanup of API to handle state preserved per
356 implementation, for various reasons, which can be void * in the APIs.
357 For now, we hack around it. */
358 tls_ext_ctx_cb
*client_static_cbinfo
= NULL
; /*XXX should not use static; multiple concurrent clients! */
359 tls_ext_ctx_cb
*server_static_cbinfo
= NULL
;
362 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
363 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*), uschar
** errstr
);
366 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
367 static int tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
);
370 static int tls_server_stapling_cb(SSL
*s
, void *arg
);
375 /* Daemon-called, before every connection, key create/rotate */
376 #ifdef EXPERIMENTAL_TLS_RESUME
377 static void tk_init(void);
378 static int tls_exdata_idx
= -1;
382 tls_daemon_init(void)
384 #ifdef EXPERIMENTAL_TLS_RESUME
391 /*************************************************
393 *************************************************/
395 /* Called from lots of places when errors occur before actually starting to do
396 the TLS handshake, that is, while the session is still in clear. Always returns
397 DEFER for a server and FAIL for a client so that most calls can use "return
398 tls_error(...)" to do this processing and then give an appropriate return. A
399 single function is used for both server and client, because it is called from
400 some shared functions.
403 prefix text to include in the logged error
404 host NULL if setting up a server;
405 the connected host if setting up a client
406 msg error message or NULL if we should ask OpenSSL
407 errstr pointer to output error message
409 Returns: OK/DEFER/FAIL
413 tls_error(uschar
* prefix
, const host_item
* host
, uschar
* msg
, uschar
** errstr
)
417 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
418 msg
= US ssl_errstring
;
421 msg
= string_sprintf("(%s): %s", prefix
, msg
);
422 DEBUG(D_tls
) debug_printf("TLS error '%s'\n", msg
);
423 if (errstr
) *errstr
= msg
;
424 return host
? FAIL
: DEFER
;
429 /*************************************************
430 * Callback to generate RSA key *
431 *************************************************/
435 s SSL connection (not used)
439 Returns: pointer to generated key
443 rsa_callback(SSL
*s
, int export
, int keylength
)
446 #ifdef EXIM_HAVE_RSA_GENKEY_EX
447 BIGNUM
*bn
= BN_new();
450 export
= export
; /* Shut picky compilers up */
451 DEBUG(D_tls
) debug_printf("Generating %d bit RSA key...\n", keylength
);
453 #ifdef EXIM_HAVE_RSA_GENKEY_EX
454 if ( !BN_set_word(bn
, (unsigned long)RSA_F4
)
455 || !(rsa_key
= RSA_new())
456 || !RSA_generate_key_ex(rsa_key
, keylength
, bn
, NULL
)
459 if (!(rsa_key
= RSA_generate_key(keylength
, RSA_F4
, NULL
, NULL
)))
463 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
464 log_write(0, LOG_MAIN
|LOG_PANIC
, "TLS error (RSA_generate_key): %s",
476 x509_store_dump_cert_s_names(X509_STORE * store)
478 STACK_OF(X509_OBJECT) * roots= store->objs;
479 static uschar name[256];
481 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
483 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
484 if(tmp_obj->type == X509_LU_X509)
486 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
487 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
489 name[sizeof(name)-1] = '\0';
490 debug_printf(" %s\n", name);
499 #ifndef DISABLE_EVENT
501 verify_event(tls_support
* tlsp
, X509
* cert
, int depth
, const uschar
* dn
,
502 BOOL
*calledp
, const BOOL
*optionalp
, const uschar
* what
)
508 ev
= tlsp
== &tls_out
? client_static_cbinfo
->event_action
: event_action
;
511 DEBUG(D_tls
) debug_printf("verify_event: %s %d\n", what
, depth
);
512 old_cert
= tlsp
->peercert
;
513 tlsp
->peercert
= X509_dup(cert
);
514 /* NB we do not bother setting peerdn */
515 if ((yield
= event_raise(ev
, US
"tls:cert", string_sprintf("%d", depth
))))
517 log_write(0, LOG_MAIN
, "[%s] %s verify denied by event-action: "
518 "depth=%d cert=%s: %s",
519 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
520 what
, depth
, dn
, yield
);
524 if (old_cert
) tlsp
->peercert
= old_cert
; /* restore 1st failing cert */
525 return 1; /* reject (leaving peercert set) */
527 DEBUG(D_tls
) debug_printf("Event-action verify failure overridden "
528 "(host in tls_try_verify_hosts)\n");
529 tlsp
->verify_override
= TRUE
;
531 X509_free(tlsp
->peercert
);
532 tlsp
->peercert
= old_cert
;
538 /*************************************************
539 * Callback for verification *
540 *************************************************/
542 /* The SSL library does certificate verification if set up to do so. This
543 callback has the current yes/no state is in "state". If verification succeeded,
544 we set the certificate-verified flag. If verification failed, what happens
545 depends on whether the client is required to present a verifiable certificate
548 If verification is optional, we change the state to yes, but still log the
549 verification error. For some reason (it really would help to have proper
550 documentation of OpenSSL), this callback function then gets called again, this
551 time with state = 1. We must take care not to set the private verified flag on
552 the second time through.
554 Note: this function is not called if the client fails to present a certificate
555 when asked. We get here only if a certificate has been received. Handling of
556 optional verification for this case is done when requesting SSL to verify, by
557 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
559 May be called multiple times for different issues with a certificate, even
560 for a given "depth" in the certificate chain.
563 preverify_ok current yes/no state as 1/0
564 x509ctx certificate information.
565 tlsp per-direction (client vs. server) support data
566 calledp has-been-called flag
567 optionalp verification-is-optional flag
569 Returns: 0 if verification should fail, otherwise 1
573 verify_callback(int preverify_ok
, X509_STORE_CTX
* x509ctx
,
574 tls_support
* tlsp
, BOOL
* calledp
, BOOL
* optionalp
)
576 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
577 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
580 if (!X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
)))
582 DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n");
583 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
584 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
);
587 dn
[sizeof(dn
)-1] = '\0';
589 if (preverify_ok
== 0)
591 uschar
* extra
= verify_mode
? string_sprintf(" (during %c-verify for [%s])",
592 *verify_mode
, sender_host_address
)
594 log_write(0, LOG_MAIN
, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
595 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
597 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx
)), dn
);
602 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
603 return 0; /* reject */
605 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
606 "tls_try_verify_hosts)\n");
607 tlsp
->verify_override
= TRUE
;
612 DEBUG(D_tls
) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth
, dn
);
614 if (tlsp
== &tls_out
&& client_static_cbinfo
->u_ocsp
.client
.verify_store
)
615 { /* client, wanting stapling */
616 /* Add the server cert's signing chain as the one
617 for the verification of the OCSP stapled information. */
619 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
622 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
625 #ifndef DISABLE_EVENT
626 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
627 return 0; /* reject, with peercert set */
632 const uschar
* verify_cert_hostnames
;
634 if ( tlsp
== &tls_out
635 && ((verify_cert_hostnames
= client_static_cbinfo
->verify_cert_hostnames
)))
636 /* client, wanting hostname check */
639 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
640 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
641 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
643 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
644 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
647 const uschar
* list
= verify_cert_hostnames
;
650 while ((name
= string_nextinlist(&list
, &sep
, NULL
, 0)))
651 if ((rc
= X509_check_host(cert
, CCS name
, 0,
652 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
653 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
,
658 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
659 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
);
666 if (!tls_is_name_for_cert(verify_cert_hostnames
, cert
))
669 uschar
* extra
= verify_mode
670 ? string_sprintf(" (during %c-verify for [%s])",
671 *verify_mode
, sender_host_address
)
673 log_write(0, LOG_MAIN
,
674 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
675 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
676 extra
, dn
, verify_cert_hostnames
);
681 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
682 return 0; /* reject */
684 DEBUG(D_tls
) debug_printf("SSL verify name failure overridden (host in "
685 "tls_try_verify_hosts)\n");
686 tlsp
->verify_override
= TRUE
;
690 #ifndef DISABLE_EVENT
691 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
692 return 0; /* reject, with peercert set */
695 DEBUG(D_tls
) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
696 *calledp
? "" : " authenticated", dn
);
700 return 1; /* accept, at least for this level */
704 verify_callback_client(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
706 return verify_callback(preverify_ok
, x509ctx
, &tls_out
,
707 &client_verify_callback_called
, &client_verify_optional
);
711 verify_callback_server(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
713 return verify_callback(preverify_ok
, x509ctx
, &tls_in
,
714 &server_verify_callback_called
, &server_verify_optional
);
720 /* This gets called *by* the dane library verify callback, which interposes
724 verify_callback_client_dane(int preverify_ok
, X509_STORE_CTX
* x509ctx
)
726 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
728 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
729 #ifndef DISABLE_EVENT
730 BOOL dummy_called
, optional
= FALSE
;
733 if (!X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
)))
735 DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n");
736 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
737 deliver_host_address
);
740 dn
[sizeof(dn
)-1] = '\0';
742 DEBUG(D_tls
) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
743 preverify_ok
? "ok":"BAD", depth
, dn
);
745 #ifndef DISABLE_EVENT
746 if (verify_event(&tls_out
, cert
, depth
, dn
,
747 &dummy_called
, &optional
, US
"DANE"))
748 return 0; /* reject, with peercert set */
751 if (preverify_ok
== 1)
753 tls_out
.dane_verified
= TRUE
;
755 if (client_static_cbinfo
->u_ocsp
.client
.verify_store
)
756 { /* client, wanting stapling */
757 /* Add the server cert's signing chain as the one
758 for the verification of the OCSP stapled information. */
760 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
763 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
769 int err
= X509_STORE_CTX_get_error(x509ctx
);
771 debug_printf(" - err %d '%s'\n", err
, X509_verify_cert_error_string(err
));
772 if (err
== X509_V_ERR_APPLICATION_VERIFICATION
)
778 #endif /*SUPPORT_DANE*/
781 /*************************************************
782 * Information callback *
783 *************************************************/
785 /* The SSL library functions call this from time to time to indicate what they
786 are doing. We copy the string to the debugging output when TLS debugging has
798 info_callback(SSL
*s
, int where
, int ret
)
804 if (where
& SSL_ST_CONNECT
)
805 str
= US
"SSL_connect";
806 else if (where
& SSL_ST_ACCEPT
)
807 str
= US
"SSL_accept";
809 str
= US
"SSL info (undefined)";
811 if (where
& SSL_CB_LOOP
)
812 debug_printf("%s: %s\n", str
, SSL_state_string_long(s
));
813 else if (where
& SSL_CB_ALERT
)
814 debug_printf("SSL3 alert %s:%s:%s\n",
815 str
= where
& SSL_CB_READ
? US
"read" : US
"write",
816 SSL_alert_type_string_long(ret
), SSL_alert_desc_string_long(ret
));
817 else if (where
& SSL_CB_EXIT
)
819 debug_printf("%s: failed in %s\n", str
, SSL_state_string_long(s
));
821 debug_printf("%s: error in %s\n", str
, SSL_state_string_long(s
));
822 else if (where
& SSL_CB_HANDSHAKE_START
)
823 debug_printf("%s: hshake start: %s\n", str
, SSL_state_string_long(s
));
824 else if (where
& SSL_CB_HANDSHAKE_DONE
)
825 debug_printf("%s: hshake done: %s\n", str
, SSL_state_string_long(s
));
829 #ifdef OPENSSL_HAVE_KEYLOG_CB
831 keylog_callback(const SSL
*ssl
, const char *line
)
833 DEBUG(D_tls
) debug_printf("%.200s\n", line
);
838 #ifdef EXPERIMENTAL_TLS_RESUME
839 /* Manage the keysets used for encrypting the session tickets, on the server. */
841 typedef struct { /* Session ticket encryption key */
844 const EVP_CIPHER
* aes_cipher
;
845 uschar aes_key
[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
846 const EVP_MD
* hmac_hash
;
852 static exim_stek exim_tk
; /* current key */
853 static exim_stek exim_tk_old
; /* previous key */
858 time_t t
= time(NULL
);
862 if (exim_tk
.renew
>= t
) return;
863 exim_tk_old
= exim_tk
;
866 if (f
.running_in_test_harness
) ssl_session_timeout
= 6;
868 DEBUG(D_tls
) debug_printf("OpenSSL: %s STEK\n", exim_tk
.name
[0] ? "rotating" : "creating");
869 if (RAND_bytes(exim_tk
.aes_key
, sizeof(exim_tk
.aes_key
)) <= 0) return;
870 if (RAND_bytes(exim_tk
.hmac_key
, sizeof(exim_tk
.hmac_key
)) <= 0) return;
871 if (RAND_bytes(exim_tk
.name
+1, sizeof(exim_tk
.name
)-1) <= 0) return;
873 exim_tk
.name
[0] = 'E';
874 exim_tk
.aes_cipher
= EVP_aes_256_cbc();
875 exim_tk
.hmac_hash
= EVP_sha256();
876 exim_tk
.expire
= t
+ ssl_session_timeout
;
877 exim_tk
.renew
= t
+ ssl_session_timeout
/2;
883 if (!exim_tk
.name
[0]) return NULL
;
888 tk_find(const uschar
* name
)
890 return memcmp(name
, exim_tk
.name
, sizeof(exim_tk
.name
)) == 0 ? &exim_tk
891 : memcmp(name
, exim_tk_old
.name
, sizeof(exim_tk_old
.name
)) == 0 ? &exim_tk_old
895 /* Callback for session tickets, on server */
897 ticket_key_callback(SSL
* ssl
, uschar key_name
[16],
898 uschar
* iv
, EVP_CIPHER_CTX
* ctx
, HMAC_CTX
* hctx
, int enc
)
900 tls_support
* tlsp
= server_static_cbinfo
->tlsp
;
905 DEBUG(D_tls
) debug_printf("ticket_key_callback: create new session\n");
906 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
908 if (RAND_bytes(iv
, EVP_MAX_IV_LENGTH
) <= 0)
909 return -1; /* insufficient random */
911 if (!(key
= tk_current())) /* current key doesn't exist or isn't valid */
912 return 0; /* key couldn't be created */
913 memcpy(key_name
, key
->name
, 16);
914 DEBUG(D_tls
) debug_printf("STEK expire %ld\n", key
->expire
- time(NULL
));
916 /*XXX will want these dependent on the ssl session strength */
917 HMAC_Init_ex(hctx
, key
->hmac_key
, sizeof(key
->hmac_key
),
918 key
->hmac_hash
, NULL
);
919 EVP_EncryptInit_ex(ctx
, key
->aes_cipher
, NULL
, key
->aes_key
, iv
);
921 DEBUG(D_tls
) debug_printf("ticket created\n");
926 time_t now
= time(NULL
);
928 DEBUG(D_tls
) debug_printf("ticket_key_callback: retrieve session\n");
929 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
931 if (!(key
= tk_find(key_name
)) || key
->expire
< now
)
935 debug_printf("ticket not usable (%s)\n", key
? "expired" : "not found");
936 if (key
) debug_printf("STEK expire %ld\n", key
->expire
- now
);
941 HMAC_Init_ex(hctx
, key
->hmac_key
, sizeof(key
->hmac_key
),
942 key
->hmac_hash
, NULL
);
943 EVP_DecryptInit_ex(ctx
, key
->aes_cipher
, NULL
, key
->aes_key
, iv
);
945 DEBUG(D_tls
) debug_printf("ticket usable, STEK expire %ld\n", key
->expire
- now
);
947 /* The ticket lifetime and renewal are the same as the STEK lifetime and
948 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
949 be better. To do that we'd have to encode ticket lifetime in the name as
950 we don't yet see the restored session. Could check posthandshake for TLS1.3
951 and trigger a new ticket then, but cannot do that for TLS1.2 */
952 return key
->renew
< now
? 2 : 1;
959 /*************************************************
960 * Initialize for DH *
961 *************************************************/
963 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
966 sctx The current SSL CTX (inbound or outbound)
967 dhparam DH parameter file or fixed parameter identity string
968 host connected host, if client; NULL if server
969 errstr error string pointer
971 Returns: TRUE if OK (nothing to set up, or setup worked)
975 init_dh(SSL_CTX
*sctx
, uschar
*dhparam
, const host_item
*host
, uschar
** errstr
)
983 if (!expand_check(dhparam
, US
"tls_dhparam", &dhexpanded
, errstr
))
986 if (!dhexpanded
|| !*dhexpanded
)
987 bio
= BIO_new_mem_buf(CS
std_dh_prime_default(), -1);
988 else if (dhexpanded
[0] == '/')
990 if (!(bio
= BIO_new_file(CS dhexpanded
, "r")))
992 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded
),
993 host
, US
strerror(errno
), errstr
);
999 if (Ustrcmp(dhexpanded
, "none") == 0)
1001 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
1005 if (!(pem
= std_dh_prime_named(dhexpanded
)))
1007 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded
),
1008 host
, US
strerror(errno
), errstr
);
1011 bio
= BIO_new_mem_buf(CS pem
, -1);
1014 if (!(dh
= PEM_read_bio_DHparams(bio
, NULL
, NULL
, NULL
)))
1017 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded
),
1018 host
, NULL
, errstr
);
1022 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
1023 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
1024 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
1025 * If someone wants to dance at the edge, then they can raise the limit or use
1026 * current libraries. */
1027 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
1028 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
1029 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
1030 dh_bitsize
= DH_bits(dh
);
1032 dh_bitsize
= 8 * DH_size(dh
);
1035 /* Even if it is larger, we silently return success rather than cause things
1036 * to fail out, so that a too-large DH will not knock out all TLS; it's a
1037 * debatable choice. */
1038 if (dh_bitsize
> tls_dh_max_bits
)
1041 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
1042 dh_bitsize
, tls_dh_max_bits
);
1046 SSL_CTX_set_tmp_dh(sctx
, dh
);
1048 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
1049 dhexpanded
? dhexpanded
: US
"default", dh_bitsize
);
1061 /*************************************************
1062 * Initialize for ECDH *
1063 *************************************************/
1065 /* Load parameters for ECDH encryption.
1067 For now, we stick to NIST P-256 because: it's simple and easy to configure;
1068 it avoids any patent issues that might bite redistributors; despite events in
1069 the news and concerns over curve choices, we're not cryptographers, we're not
1070 pretending to be, and this is "good enough" to be better than no support,
1071 protecting against most adversaries. Given another year or two, there might
1072 be sufficient clarity about a "right" way forward to let us make an informed
1073 decision, instead of a knee-jerk reaction.
1075 Longer-term, we should look at supporting both various named curves and
1076 external files generated with "openssl ecparam", much as we do for init_dh().
1077 We should also support "none" as a value, to explicitly avoid initialisation.
1082 sctx The current SSL CTX (inbound or outbound)
1083 host connected host, if client; NULL if server
1084 errstr error string pointer
1086 Returns: TRUE if OK (nothing to set up, or setup worked)
1090 init_ecdh(SSL_CTX
* sctx
, host_item
* host
, uschar
** errstr
)
1092 #ifdef OPENSSL_NO_ECDH
1101 if (host
) /* No ECDH setup for clients, only for servers */
1104 # ifndef EXIM_HAVE_ECDH
1106 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
1110 if (!expand_check(tls_eccurve
, US
"tls_eccurve", &exp_curve
, errstr
))
1112 if (!exp_curve
|| !*exp_curve
)
1115 /* "auto" needs to be handled carefully.
1116 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
1117 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
1118 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
1119 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
1120 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
1122 if (Ustrcmp(exp_curve
, "auto") == 0)
1124 #if OPENSSL_VERSION_NUMBER < 0x10002000L
1125 DEBUG(D_tls
) debug_printf(
1126 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
1127 exp_curve
= US
"prime256v1";
1129 # if defined SSL_CTRL_SET_ECDH_AUTO
1130 DEBUG(D_tls
) debug_printf(
1131 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
1132 SSL_CTX_set_ecdh_auto(sctx
, 1);
1135 DEBUG(D_tls
) debug_printf(
1136 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
1142 DEBUG(D_tls
) debug_printf("ECDH: curve '%s'\n", exp_curve
);
1143 if ( (nid
= OBJ_sn2nid (CCS exp_curve
)) == NID_undef
1144 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
1145 && (nid
= EC_curve_nist2nid(CCS exp_curve
)) == NID_undef
1149 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve
),
1150 host
, NULL
, errstr
);
1154 if (!(ecdh
= EC_KEY_new_by_curve_name(nid
)))
1156 tls_error(US
"Unable to create ec curve", host
, NULL
, errstr
);
1160 /* The "tmp" in the name here refers to setting a temporary key
1161 not to the stability of the interface. */
1163 if ((rv
= SSL_CTX_set_tmp_ecdh(sctx
, ecdh
) == 0))
1164 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve
), host
, NULL
, errstr
);
1166 DEBUG(D_tls
) debug_printf("ECDH: enabled '%s' curve\n", exp_curve
);
1171 # endif /*EXIM_HAVE_ECDH*/
1172 #endif /*OPENSSL_NO_ECDH*/
1178 #ifndef DISABLE_OCSP
1179 /*************************************************
1180 * Load OCSP information into state *
1181 *************************************************/
1182 /* Called to load the server OCSP response from the given file into memory, once
1183 caller has determined this is needed. Checks validity. Debugs a message
1186 ASSUMES: single response, for single cert.
1189 sctx the SSL_CTX* to update
1190 cbinfo various parts of session state
1191 expanded the filename putatively holding an OCSP response
1196 ocsp_load_response(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
, const uschar
*expanded
)
1199 OCSP_RESPONSE
* resp
;
1200 OCSP_BASICRESP
* basic_response
;
1201 OCSP_SINGLERESP
* single_response
;
1202 ASN1_GENERALIZEDTIME
* rev
, * thisupd
, * nextupd
;
1203 STACK_OF(X509
) * sk
;
1204 unsigned long verify_flags
;
1205 int status
, reason
, i
;
1207 cbinfo
->u_ocsp
.server
.file_expanded
= string_copy(expanded
);
1208 if (cbinfo
->u_ocsp
.server
.response
)
1210 OCSP_RESPONSE_free(cbinfo
->u_ocsp
.server
.response
);
1211 cbinfo
->u_ocsp
.server
.response
= NULL
;
1214 if (!(bio
= BIO_new_file(CS cbinfo
->u_ocsp
.server
.file_expanded
, "rb")))
1216 DEBUG(D_tls
) debug_printf("Failed to open OCSP response file \"%s\"\n",
1217 cbinfo
->u_ocsp
.server
.file_expanded
);
1221 resp
= d2i_OCSP_RESPONSE_bio(bio
, NULL
);
1225 DEBUG(D_tls
) debug_printf("Error reading OCSP response.\n");
1229 if ((status
= OCSP_response_status(resp
)) != OCSP_RESPONSE_STATUS_SUCCESSFUL
)
1231 DEBUG(D_tls
) debug_printf("OCSP response not valid: %s (%d)\n",
1232 OCSP_response_status_str(status
), status
);
1236 if (!(basic_response
= OCSP_response_get1_basic(resp
)))
1239 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1243 sk
= cbinfo
->verify_stack
;
1244 verify_flags
= OCSP_NOVERIFY
; /* check sigs, but not purpose */
1246 /* May need to expose ability to adjust those flags?
1247 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1248 OCSP_TRUSTOTHER OCSP_NOINTERN */
1250 /* This does a full verify on the OCSP proof before we load it for serving
1251 up; possibly overkill - just date-checks might be nice enough.
1253 OCSP_basic_verify takes a "store" arg, but does not
1254 use it for the chain verification, which is all we do
1255 when OCSP_NOVERIFY is set. The content from the wire
1256 "basic_response" and a cert-stack "sk" are all that is used.
1258 We have a stack, loaded in setup_certs() if tls_verify_certificates
1259 was a file (not a directory, or "system"). It is unfortunate we
1260 cannot used the connection context store, as that would neatly
1261 handle the "system" case too, but there seems to be no library
1262 function for getting a stack from a store.
1263 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1264 We do not free the stack since it could be needed a second time for
1267 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1268 be a public interface into the OpenSSL library (there's no manual entry) -
1269 But what with? We also use OCSP_basic_verify in the client stapling callback.
1270 And there we NEED it; we must verify that status... unless the
1271 library does it for us anyway? */
1273 if ((i
= OCSP_basic_verify(basic_response
, sk
, NULL
, verify_flags
)) < 0)
1277 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
1278 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring
);
1283 /* Here's the simplifying assumption: there's only one response, for the
1284 one certificate we use, and nothing for anything else in a chain. If this
1285 proves false, we need to extract a cert id from our issued cert
1286 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1287 right cert in the stack and then calls OCSP_single_get0_status()).
1289 I'm hoping to avoid reworking a bunch more of how we handle state here. */
1291 if (!(single_response
= OCSP_resp_get0(basic_response
, 0)))
1294 debug_printf("Unable to get first response from OCSP basic response.\n");
1298 status
= OCSP_single_get0_status(single_response
, &reason
, &rev
, &thisupd
, &nextupd
);
1299 if (status
!= V_OCSP_CERTSTATUS_GOOD
)
1301 DEBUG(D_tls
) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1302 OCSP_cert_status_str(status
), status
,
1303 OCSP_crl_reason_str(reason
), reason
);
1307 if (!OCSP_check_validity(thisupd
, nextupd
, EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1309 DEBUG(D_tls
) debug_printf("OCSP status invalid times.\n");
1314 cbinfo
->u_ocsp
.server
.response
= resp
; /*XXX stack?*/
1318 if (f
.running_in_test_harness
)
1320 extern char ** environ
;
1321 if (environ
) for (uschar
** p
= USS environ
; *p
; p
++)
1322 if (Ustrncmp(*p
, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1324 DEBUG(D_tls
) debug_printf("Supplying known bad OCSP response\n");
1325 goto supply_response
;
1330 #endif /*!DISABLE_OCSP*/
1335 /* Create and install a selfsigned certificate, for use in server mode */
1338 tls_install_selfsign(SSL_CTX
* sctx
, uschar
** errstr
)
1346 where
= US
"allocating pkey";
1347 if (!(pkey
= EVP_PKEY_new()))
1350 where
= US
"allocating cert";
1351 if (!(x509
= X509_new()))
1354 where
= US
"generating pkey";
1355 if (!(rsa
= rsa_callback(NULL
, 0, 2048)))
1358 where
= US
"assigning pkey";
1359 if (!EVP_PKEY_assign_RSA(pkey
, rsa
))
1362 X509_set_version(x509
, 2); /* N+1 - version 3 */
1363 ASN1_INTEGER_set(X509_get_serialNumber(x509
), 1);
1364 X509_gmtime_adj(X509_get_notBefore(x509
), 0);
1365 X509_gmtime_adj(X509_get_notAfter(x509
), (long)60 * 60); /* 1 hour */
1366 X509_set_pubkey(x509
, pkey
);
1368 name
= X509_get_subject_name(x509
);
1369 X509_NAME_add_entry_by_txt(name
, "C",
1370 MBSTRING_ASC
, CUS
"UK", -1, -1, 0);
1371 X509_NAME_add_entry_by_txt(name
, "O",
1372 MBSTRING_ASC
, CUS
"Exim Developers", -1, -1, 0);
1373 X509_NAME_add_entry_by_txt(name
, "CN",
1374 MBSTRING_ASC
, CUS smtp_active_hostname
, -1, -1, 0);
1375 X509_set_issuer_name(x509
, name
);
1377 where
= US
"signing cert";
1378 if (!X509_sign(x509
, pkey
, EVP_md5()))
1381 where
= US
"installing selfsign cert";
1382 if (!SSL_CTX_use_certificate(sctx
, x509
))
1385 where
= US
"installing selfsign key";
1386 if (!SSL_CTX_use_PrivateKey(sctx
, pkey
))
1392 (void) tls_error(where
, NULL
, NULL
, errstr
);
1393 if (x509
) X509_free(x509
);
1394 if (pkey
) EVP_PKEY_free(pkey
);
1402 tls_add_certfile(SSL_CTX
* sctx
, tls_ext_ctx_cb
* cbinfo
, uschar
* file
,
1405 DEBUG(D_tls
) debug_printf("tls_certificate file %s\n", file
);
1406 if (!SSL_CTX_use_certificate_chain_file(sctx
, CS file
))
1407 return tls_error(string_sprintf(
1408 "SSL_CTX_use_certificate_chain_file file=%s", file
),
1409 cbinfo
->host
, NULL
, errstr
);
1414 tls_add_pkeyfile(SSL_CTX
* sctx
, tls_ext_ctx_cb
* cbinfo
, uschar
* file
,
1417 DEBUG(D_tls
) debug_printf("tls_privatekey file %s\n", file
);
1418 if (!SSL_CTX_use_PrivateKey_file(sctx
, CS file
, SSL_FILETYPE_PEM
))
1419 return tls_error(string_sprintf(
1420 "SSL_CTX_use_PrivateKey_file file=%s", file
), cbinfo
->host
, NULL
, errstr
);
1425 /*************************************************
1426 * Expand key and cert file specs *
1427 *************************************************/
1429 /* Called once during tls_init and possibly again during TLS setup, for a
1430 new context, if Server Name Indication was used and tls_sni was seen in
1431 the certificate string.
1434 sctx the SSL_CTX* to update
1435 cbinfo various parts of session state
1436 errstr error string pointer
1438 Returns: OK/DEFER/FAIL
1442 tls_expand_session_files(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
,
1447 if (!cbinfo
->certificate
)
1449 if (!cbinfo
->is_server
) /* client */
1452 if (tls_install_selfsign(sctx
, errstr
) != OK
)
1459 if (Ustrstr(cbinfo
->certificate
, US
"tls_sni") ||
1460 Ustrstr(cbinfo
->certificate
, US
"tls_in_sni") ||
1461 Ustrstr(cbinfo
->certificate
, US
"tls_out_sni")
1463 reexpand_tls_files_for_sni
= TRUE
;
1465 if (!expand_check(cbinfo
->certificate
, US
"tls_certificate", &expanded
, errstr
))
1469 if (cbinfo
->is_server
)
1471 const uschar
* file_list
= expanded
;
1475 while (file
= string_nextinlist(&file_list
, &sep
, NULL
, 0))
1476 if ((err
= tls_add_certfile(sctx
, cbinfo
, file
, errstr
)))
1479 else /* would there ever be a need for multiple client certs? */
1480 if ((err
= tls_add_certfile(sctx
, cbinfo
, expanded
, errstr
)))
1483 if ( cbinfo
->privatekey
1484 && !expand_check(cbinfo
->privatekey
, US
"tls_privatekey", &expanded
, errstr
))
1487 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1488 of the expansion is an empty string, ignore it also, and assume the private
1489 key is in the same file as the certificate. */
1491 if (expanded
&& *expanded
)
1492 if (cbinfo
->is_server
)
1494 const uschar
* file_list
= expanded
;
1498 while (file
= string_nextinlist(&file_list
, &sep
, NULL
, 0))
1499 if ((err
= tls_add_pkeyfile(sctx
, cbinfo
, file
, errstr
)))
1502 else /* would there ever be a need for multiple client certs? */
1503 if ((err
= tls_add_pkeyfile(sctx
, cbinfo
, expanded
, errstr
)))
1507 #ifndef DISABLE_OCSP
1508 if (cbinfo
->is_server
&& cbinfo
->u_ocsp
.server
.file
)
1511 if (!expand_check(cbinfo
->u_ocsp
.server
.file
, US
"tls_ocsp_file", &expanded
, errstr
))
1514 if (expanded
&& *expanded
)
1516 DEBUG(D_tls
) debug_printf("tls_ocsp_file %s\n", expanded
);
1517 if ( cbinfo
->u_ocsp
.server
.file_expanded
1518 && (Ustrcmp(expanded
, cbinfo
->u_ocsp
.server
.file_expanded
) == 0))
1520 DEBUG(D_tls
) debug_printf(" - value unchanged, using existing values\n");
1523 ocsp_load_response(sctx
, cbinfo
, expanded
);
1534 /*************************************************
1535 * Callback to handle SNI *
1536 *************************************************/
1538 /* Called when acting as server during the TLS session setup if a Server Name
1539 Indication extension was sent by the client.
1541 API documentation is OpenSSL s_server.c implementation.
1544 s SSL* of the current session
1545 ad unknown (part of OpenSSL API) (unused)
1546 arg Callback of "our" registered data
1548 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1550 XXX might need to change to using ClientHello callback,
1551 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
1554 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1556 tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
)
1558 const char *servername
= SSL_get_servername(s
, TLSEXT_NAMETYPE_host_name
);
1559 tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1561 int old_pool
= store_pool
;
1562 uschar
* dummy_errstr
;
1565 return SSL_TLSEXT_ERR_OK
;
1567 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", servername
,
1568 reexpand_tls_files_for_sni
? "" : " (unused for certificate selection)");
1570 /* Make the extension value available for expansion */
1571 store_pool
= POOL_PERM
;
1572 tls_in
.sni
= string_copy(US servername
);
1573 store_pool
= old_pool
;
1575 if (!reexpand_tls_files_for_sni
)
1576 return SSL_TLSEXT_ERR_OK
;
1578 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1579 not confident that memcpy wouldn't break some internal reference counting.
1580 Especially since there's a references struct member, which would be off. */
1582 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1583 if (!(server_sni
= SSL_CTX_new(TLS_server_method())))
1585 if (!(server_sni
= SSL_CTX_new(SSLv23_server_method())))
1588 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
1589 DEBUG(D_tls
) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring
);
1593 /* Not sure how many of these are actually needed, since SSL object
1594 already exists. Might even need this selfsame callback, for reneg? */
1596 SSL_CTX_set_info_callback(server_sni
, SSL_CTX_get_info_callback(server_ctx
));
1597 SSL_CTX_set_mode(server_sni
, SSL_CTX_get_mode(server_ctx
));
1598 SSL_CTX_set_options(server_sni
, SSL_CTX_get_options(server_ctx
));
1599 SSL_CTX_set_timeout(server_sni
, SSL_CTX_get_timeout(server_ctx
));
1600 SSL_CTX_set_tlsext_servername_callback(server_sni
, tls_servername_cb
);
1601 SSL_CTX_set_tlsext_servername_arg(server_sni
, cbinfo
);
1603 if ( !init_dh(server_sni
, cbinfo
->dhparam
, NULL
, &dummy_errstr
)
1604 || !init_ecdh(server_sni
, NULL
, &dummy_errstr
)
1608 if ( cbinfo
->server_cipher_list
1609 && !SSL_CTX_set_cipher_list(server_sni
, CS cbinfo
->server_cipher_list
))
1612 #ifndef DISABLE_OCSP
1613 if (cbinfo
->u_ocsp
.server
.file
)
1615 SSL_CTX_set_tlsext_status_cb(server_sni
, tls_server_stapling_cb
);
1616 SSL_CTX_set_tlsext_status_arg(server_sni
, cbinfo
);
1620 if ((rc
= setup_certs(server_sni
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
,
1621 verify_callback_server
, &dummy_errstr
)) != OK
)
1624 /* do this after setup_certs, because this can require the certs for verifying
1625 OCSP information. */
1626 if ((rc
= tls_expand_session_files(server_sni
, cbinfo
, &dummy_errstr
)) != OK
)
1629 DEBUG(D_tls
) debug_printf("Switching SSL context.\n");
1630 SSL_set_SSL_CTX(s
, server_sni
);
1631 return SSL_TLSEXT_ERR_OK
;
1633 bad
: return SSL_TLSEXT_ERR_ALERT_FATAL
;
1635 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1640 #ifndef DISABLE_OCSP
1642 /*************************************************
1643 * Callback to handle OCSP Stapling *
1644 *************************************************/
1646 /* Called when acting as server during the TLS session setup if the client
1647 requests OCSP information with a Certificate Status Request.
1649 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1655 tls_server_stapling_cb(SSL
*s
, void *arg
)
1657 const tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1658 uschar
*response_der
; /*XXX blob */
1659 int response_der_len
;
1661 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1662 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1663 buggy in current OpenSSL; it returns the last cert loaded always rather than
1664 the one actually presented. So we can't support a stack of OCSP proofs at
1668 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1669 cbinfo
->u_ocsp
.server
.response
? "have" : "lack");
1671 tls_in
.ocsp
= OCSP_NOT_RESP
;
1672 if (!cbinfo
->u_ocsp
.server
.response
)
1673 return SSL_TLSEXT_ERR_NOACK
;
1675 response_der
= NULL
;
1676 response_der_len
= i2d_OCSP_RESPONSE(cbinfo
->u_ocsp
.server
.response
, /*XXX stack*/
1678 if (response_der_len
<= 0)
1679 return SSL_TLSEXT_ERR_NOACK
;
1681 SSL_set_tlsext_status_ocsp_resp(server_ssl
, response_der
, response_der_len
);
1682 tls_in
.ocsp
= OCSP_VFIED
;
1683 return SSL_TLSEXT_ERR_OK
;
1688 time_print(BIO
* bp
, const char * str
, ASN1_GENERALIZEDTIME
* time
)
1690 BIO_printf(bp
, "\t%s: ", str
);
1691 ASN1_GENERALIZEDTIME_print(bp
, time
);
1696 tls_client_stapling_cb(SSL
*s
, void *arg
)
1698 tls_ext_ctx_cb
* cbinfo
= arg
;
1699 const unsigned char * p
;
1701 OCSP_RESPONSE
* rsp
;
1702 OCSP_BASICRESP
* bs
;
1705 DEBUG(D_tls
) debug_printf("Received TLS status response (OCSP stapling):");
1706 len
= SSL_get_tlsext_status_ocsp_resp(s
, &p
);
1709 /* Expect this when we requested ocsp but got none */
1710 if (cbinfo
->u_ocsp
.client
.verify_required
&& LOGGING(tls_cipher
))
1711 log_write(0, LOG_MAIN
, "Received TLS status callback, null content");
1713 DEBUG(D_tls
) debug_printf(" null\n");
1714 return cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1717 if(!(rsp
= d2i_OCSP_RESPONSE(NULL
, &p
, len
)))
1719 tls_out
.ocsp
= OCSP_FAILED
;
1720 if (LOGGING(tls_cipher
))
1721 log_write(0, LOG_MAIN
, "Received TLS cert status response, parse error");
1723 DEBUG(D_tls
) debug_printf(" parse error\n");
1727 if(!(bs
= OCSP_response_get1_basic(rsp
)))
1729 tls_out
.ocsp
= OCSP_FAILED
;
1730 if (LOGGING(tls_cipher
))
1731 log_write(0, LOG_MAIN
, "Received TLS cert status response, error parsing response");
1733 DEBUG(D_tls
) debug_printf(" error parsing response\n");
1734 OCSP_RESPONSE_free(rsp
);
1738 /* We'd check the nonce here if we'd put one in the request. */
1739 /* However that would defeat cacheability on the server so we don't. */
1741 /* This section of code reworked from OpenSSL apps source;
1742 The OpenSSL Project retains copyright:
1743 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1748 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
1750 DEBUG(D_tls
) bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
1752 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1754 /* Use the chain that verified the server cert to verify the stapled info */
1755 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1757 if ((i
= OCSP_basic_verify(bs
, cbinfo
->verify_stack
,
1758 cbinfo
->u_ocsp
.client
.verify_store
, 0)) <= 0)
1760 tls_out
.ocsp
= OCSP_FAILED
;
1761 if (LOGGING(tls_cipher
)) log_write(0, LOG_MAIN
,
1762 "Received TLS cert status response, itself unverifiable: %s",
1763 ERR_reason_error_string(ERR_peek_error()));
1764 BIO_printf(bp
, "OCSP response verify failure\n");
1765 ERR_print_errors(bp
);
1766 OCSP_RESPONSE_print(bp
, rsp
, 0);
1770 BIO_printf(bp
, "OCSP response well-formed and signed OK\n");
1772 /*XXX So we have a good stapled OCSP status. How do we know
1773 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1774 OCSP_resp_find_status() which matches on a cert id, which presumably
1775 we should use. Making an id needs OCSP_cert_id_new(), which takes
1776 issuerName, issuerKey, serialNumber. Are they all in the cert?
1778 For now, carry on blindly accepting the resp. */
1781 OCSP_SINGLERESP
* single
;
1783 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1784 if (OCSP_resp_count(bs
) != 1)
1786 STACK_OF(OCSP_SINGLERESP
) * sresp
= bs
->tbsResponseData
->responses
;
1787 if (sk_OCSP_SINGLERESP_num(sresp
) != 1)
1790 tls_out
.ocsp
= OCSP_FAILED
;
1791 log_write(0, LOG_MAIN
, "OCSP stapling "
1792 "with multiple responses not handled");
1795 single
= OCSP_resp_get0(bs
, 0);
1796 status
= OCSP_single_get0_status(single
, &reason
, &rev
,
1797 &thisupd
, &nextupd
);
1800 DEBUG(D_tls
) time_print(bp
, "This OCSP Update", thisupd
);
1801 DEBUG(D_tls
) if(nextupd
) time_print(bp
, "Next OCSP Update", nextupd
);
1802 if (!OCSP_check_validity(thisupd
, nextupd
,
1803 EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1805 tls_out
.ocsp
= OCSP_FAILED
;
1806 DEBUG(D_tls
) ERR_print_errors(bp
);
1807 log_write(0, LOG_MAIN
, "Server OSCP dates invalid");
1811 DEBUG(D_tls
) BIO_printf(bp
, "Certificate status: %s\n",
1812 OCSP_cert_status_str(status
));
1815 case V_OCSP_CERTSTATUS_GOOD
:
1816 tls_out
.ocsp
= OCSP_VFIED
;
1819 case V_OCSP_CERTSTATUS_REVOKED
:
1820 tls_out
.ocsp
= OCSP_FAILED
;
1821 log_write(0, LOG_MAIN
, "Server certificate revoked%s%s",
1822 reason
!= -1 ? "; reason: " : "",
1823 reason
!= -1 ? OCSP_crl_reason_str(reason
) : "");
1824 DEBUG(D_tls
) time_print(bp
, "Revocation Time", rev
);
1827 tls_out
.ocsp
= OCSP_FAILED
;
1828 log_write(0, LOG_MAIN
,
1829 "Server certificate status unknown, in OCSP stapling");
1834 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1839 OCSP_RESPONSE_free(rsp
);
1842 #endif /*!DISABLE_OCSP*/
1845 /*************************************************
1846 * Initialize for TLS *
1847 *************************************************/
1849 /* Called from both server and client code, to do preliminary initialization
1850 of the library. We allocate and return a context structure.
1853 ctxp returned SSL context
1854 host connected host, if client; NULL if server
1855 dhparam DH parameter file
1856 certificate certificate file
1857 privatekey private key
1858 ocsp_file file of stapling info (server); flag for require ocsp (client)
1859 addr address if client; NULL if server (for some randomness)
1860 cbp place to put allocated callback context
1861 errstr error string pointer
1863 Returns: OK/DEFER/FAIL
1867 tls_init(SSL_CTX
**ctxp
, host_item
*host
, uschar
*dhparam
, uschar
*certificate
,
1869 #ifndef DISABLE_OCSP
1870 uschar
*ocsp_file
, /*XXX stack, in server*/
1872 address_item
*addr
, tls_ext_ctx_cb
** cbp
,
1879 tls_ext_ctx_cb
* cbinfo
;
1881 cbinfo
= store_malloc(sizeof(tls_ext_ctx_cb
));
1882 cbinfo
->tlsp
= tlsp
;
1883 cbinfo
->certificate
= certificate
;
1884 cbinfo
->privatekey
= privatekey
;
1885 cbinfo
->is_server
= host
==NULL
;
1886 #ifndef DISABLE_OCSP
1887 cbinfo
->verify_stack
= NULL
;
1890 cbinfo
->u_ocsp
.server
.file
= ocsp_file
;
1891 cbinfo
->u_ocsp
.server
.file_expanded
= NULL
;
1892 cbinfo
->u_ocsp
.server
.response
= NULL
;
1895 cbinfo
->u_ocsp
.client
.verify_store
= NULL
;
1897 cbinfo
->dhparam
= dhparam
;
1898 cbinfo
->server_cipher_list
= NULL
;
1899 cbinfo
->host
= host
;
1900 #ifndef DISABLE_EVENT
1901 cbinfo
->event_action
= NULL
;
1904 #ifdef EXIM_NEED_OPENSSL_INIT
1905 SSL_load_error_strings(); /* basic set up */
1906 OpenSSL_add_ssl_algorithms();
1909 #ifdef EXIM_HAVE_SHA256
1910 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1911 list of available digests. */
1912 EVP_add_digest(EVP_sha256());
1915 /* Create a context.
1916 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1917 negotiation in the different methods; as far as I can tell, the only
1918 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1919 when OpenSSL is built without SSLv2 support.
1920 By disabling with openssl_options, we can let admins re-enable with the
1923 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1924 if (!(ctx
= SSL_CTX_new(host
? TLS_client_method() : TLS_server_method())))
1926 if (!(ctx
= SSL_CTX_new(host
? SSLv23_client_method() : SSLv23_server_method())))
1928 return tls_error(US
"SSL_CTX_new", host
, NULL
, errstr
);
1930 /* It turns out that we need to seed the random number generator this early in
1931 order to get the full complement of ciphers to work. It took me roughly a day
1932 of work to discover this by experiment.
1934 On systems that have /dev/urandom, SSL may automatically seed itself from
1935 there. Otherwise, we have to make something up as best we can. Double check
1941 gettimeofday(&r
.tv
, NULL
);
1944 RAND_seed(US (&r
), sizeof(r
));
1945 RAND_seed(US big_buffer
, big_buffer_size
);
1946 if (addr
!= NULL
) RAND_seed(US addr
, sizeof(addr
));
1949 return tls_error(US
"RAND_status", host
,
1950 US
"unable to seed random number generator", errstr
);
1953 /* Set up the information callback, which outputs if debugging is at a suitable
1958 SSL_CTX_set_info_callback(ctx
, (void (*)())info_callback
);
1959 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1960 /* this needs a debug build of OpenSSL */
1961 SSL_CTX_set_msg_callback(ctx
, (void (*)())SSL_trace
);
1963 #ifdef OPENSSL_HAVE_KEYLOG_CB
1964 SSL_CTX_set_keylog_callback(ctx
, (void (*)())keylog_callback
);
1968 /* Automatically re-try reads/writes after renegotiation. */
1969 (void) SSL_CTX_set_mode(ctx
, SSL_MODE_AUTO_RETRY
);
1971 /* Apply administrator-supplied work-arounds.
1972 Historically we applied just one requested option,
1973 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1974 moved to an administrator-controlled list of options to specify and
1975 grandfathered in the first one as the default value for "openssl_options".
1977 No OpenSSL version number checks: the options we accept depend upon the
1978 availability of the option value macros from OpenSSL. */
1980 if (!tls_openssl_options_parse(openssl_options
, &init_options
))
1981 return tls_error(US
"openssl_options parsing failed", host
, NULL
, errstr
);
1983 #ifdef EXPERIMENTAL_TLS_RESUME
1984 tlsp
->resumption
= RESUME_SUPPORTED
;
1988 #ifdef EXPERIMENTAL_TLS_RESUME
1989 /* Should the server offer session resumption? */
1990 if (!host
&& verify_check_host(&tls_resumption_hosts
) == OK
)
1992 DEBUG(D_tls
) debug_printf("tls_resumption_hosts overrides openssl_options\n");
1993 init_options
&= ~SSL_OP_NO_TICKET
;
1994 tlsp
->resumption
|= RESUME_SERVER_TICKET
; /* server will give ticket on request */
1995 tlsp
->host_resumable
= TRUE
;
1999 DEBUG(D_tls
) debug_printf("setting SSL CTX options: %#lx\n", init_options
);
2000 if (!(SSL_CTX_set_options(ctx
, init_options
)))
2001 return tls_error(string_sprintf(
2002 "SSL_CTX_set_option(%#lx)", init_options
), host
, NULL
, errstr
);
2005 DEBUG(D_tls
) debug_printf("no SSL CTX options to set\n");
2007 /* We'd like to disable session cache unconditionally, but foolish Outlook
2008 Express clients then give up the first TLS connection and make a second one
2009 (which works). Only when there is an IMAP service on the same machine.
2010 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2011 now, until we work out a decent way of presenting control to the config. It
2012 will never be used because we use a new context every time. */
2014 (void) SSL_CTX_set_session_cache_mode(ctx
, SSL_SESS_CACHE_OFF
);
2017 /* Initialize with DH parameters if supplied */
2018 /* Initialize ECDH temp key parameter selection */
2020 if ( !init_dh(ctx
, dhparam
, host
, errstr
)
2021 || !init_ecdh(ctx
, host
, errstr
)
2025 /* Set up certificate and key (and perhaps OCSP info) */
2027 if ((rc
= tls_expand_session_files(ctx
, cbinfo
, errstr
)) != OK
)
2030 /* If we need to handle SNI or OCSP, do so */
2032 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2033 # ifndef DISABLE_OCSP
2034 if (!(cbinfo
->verify_stack
= sk_X509_new_null()))
2036 DEBUG(D_tls
) debug_printf("failed to create stack for stapling verify\n");
2041 if (!host
) /* server */
2043 # ifndef DISABLE_OCSP
2044 /* We check u_ocsp.server.file, not server.response, because we care about if
2045 the option exists, not what the current expansion might be, as SNI might
2046 change the certificate and OCSP file in use between now and the time the
2047 callback is invoked. */
2048 if (cbinfo
->u_ocsp
.server
.file
)
2050 SSL_CTX_set_tlsext_status_cb(ctx
, tls_server_stapling_cb
);
2051 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
2054 /* We always do this, so that $tls_sni is available even if not used in
2056 SSL_CTX_set_tlsext_servername_callback(ctx
, tls_servername_cb
);
2057 SSL_CTX_set_tlsext_servername_arg(ctx
, cbinfo
);
2059 # ifndef DISABLE_OCSP
2061 if(ocsp_file
) /* wanting stapling */
2063 if (!(cbinfo
->u_ocsp
.client
.verify_store
= X509_STORE_new()))
2065 DEBUG(D_tls
) debug_printf("failed to create store for stapling verify\n");
2068 SSL_CTX_set_tlsext_status_cb(ctx
, tls_client_stapling_cb
);
2069 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
2074 cbinfo
->verify_cert_hostnames
= NULL
;
2076 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2077 /* Set up the RSA callback */
2078 SSL_CTX_set_tmp_rsa_callback(ctx
, rsa_callback
);
2081 /* Finally, set the session cache timeout, and we are done.
2082 The period appears to be also used for (server-generated) session tickets */
2084 SSL_CTX_set_timeout(ctx
, ssl_session_timeout
);
2085 DEBUG(D_tls
) debug_printf("Initialized TLS\n");
2096 /*************************************************
2097 * Get name of cipher in use *
2098 *************************************************/
2101 Argument: pointer to an SSL structure for the connection
2102 pointer to number of bits for cipher
2103 Returns: pointer to allocated string in perm-pool
2107 construct_cipher_name(SSL
* ssl
, int * bits
)
2109 int pool
= store_pool
;
2110 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2111 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2112 the accessor functions use const in the prototype. */
2114 const uschar
* ver
= CUS
SSL_get_version(ssl
);
2115 const SSL_CIPHER
* c
= (const SSL_CIPHER
*) SSL_get_current_cipher(ssl
);
2118 SSL_CIPHER_get_bits(c
, bits
);
2120 store_pool
= POOL_PERM
;
2121 s
= string_sprintf("%s:%s:%u", ver
, SSL_CIPHER_get_name(c
), *bits
);
2123 DEBUG(D_tls
) debug_printf("Cipher: %s\n", s
);
2128 /* Get IETF-standard name for ciphersuite.
2129 Argument: pointer to an SSL structure for the connection
2130 Returns: pointer to string
2133 static const uschar
*
2134 cipher_stdname_ssl(SSL
* ssl
)
2136 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2137 return CUS
SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl
));
2139 ushort id
= 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl
));
2140 return cipher_stdname(id
>> 8, id
& 0xff);
2146 peer_cert(SSL
* ssl
, tls_support
* tlsp
, uschar
* peerdn
, unsigned siz
)
2148 /*XXX we might consider a list-of-certs variable for the cert chain.
2149 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2150 in list-handling functions, also consider the difference between the entire
2151 chain and the elements sent by the peer. */
2153 tlsp
->peerdn
= NULL
;
2155 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2156 if (!tlsp
->peercert
)
2157 tlsp
->peercert
= SSL_get_peer_certificate(ssl
);
2158 /* Beware anonymous ciphers which lead to server_cert being NULL */
2160 if (!X509_NAME_oneline(X509_get_subject_name(tlsp
->peercert
), CS peerdn
, siz
))
2161 { DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n"); }
2164 int oldpool
= store_pool
;
2166 peerdn
[siz
-1] = '\0'; /* paranoia */
2167 store_pool
= POOL_PERM
;
2168 tlsp
->peerdn
= string_copy(peerdn
);
2169 store_pool
= oldpool
;
2171 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2172 but they don't get called on session-resumption. So use the official
2173 interface, which uses the resumed value. Unfortunately this claims verified
2174 when it actually failed but we're in try-verify mode, due to us wanting the
2175 knowlege that it failed so needing to have the callback and forcing a
2176 permissive return. If we don't force it, the TLS startup is failed.
2177 Hence the verify_override bodge - though still a problem for resumption. */
2179 if (!tlsp
->verify_override
)
2180 tlsp
->certificate_verified
= SSL_get_verify_result(ssl
) == X509_V_OK
;
2188 /*************************************************
2189 * Set up for verifying certificates *
2190 *************************************************/
2192 #ifndef DISABLE_OCSP
2193 /* Load certs from file, return TRUE on success */
2196 chain_from_pem_file(const uschar
* file
, STACK_OF(X509
) * verify_stack
)
2201 while (sk_X509_num(verify_stack
) > 0)
2202 X509_free(sk_X509_pop(verify_stack
));
2204 if (!(bp
= BIO_new_file(CS file
, "r"))) return FALSE
;
2205 while ((x
= PEM_read_bio_X509(bp
, NULL
, 0, NULL
)))
2206 sk_X509_push(verify_stack
, x
);
2214 /* Called by both client and server startup; on the server possibly
2215 repeated after a Server Name Indication.
2218 sctx SSL_CTX* to initialise
2219 certs certs file or NULL
2220 crl CRL file or NULL
2221 host NULL in a server; the remote host in a client
2222 optional TRUE if called from a server for a host in tls_try_verify_hosts;
2223 otherwise passed as FALSE
2224 cert_vfy_cb Callback function for certificate verification
2225 errstr error string pointer
2227 Returns: OK/DEFER/FAIL
2231 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
2232 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*), uschar
** errstr
)
2234 uschar
*expcerts
, *expcrl
;
2236 if (!expand_check(certs
, US
"tls_verify_certificates", &expcerts
, errstr
))
2238 DEBUG(D_tls
) debug_printf("tls_verify_certificates: %s\n", expcerts
);
2240 if (expcerts
&& *expcerts
)
2242 /* Tell the library to use its compiled-in location for the system default
2243 CA bundle. Then add the ones specified in the config, if any. */
2245 if (!SSL_CTX_set_default_verify_paths(sctx
))
2246 return tls_error(US
"SSL_CTX_set_default_verify_paths", host
, NULL
, errstr
);
2248 if (Ustrcmp(expcerts
, "system") != 0)
2250 struct stat statbuf
;
2252 if (Ustat(expcerts
, &statbuf
) < 0)
2254 log_write(0, LOG_MAIN
|LOG_PANIC
,
2255 "failed to stat %s for certificates", expcerts
);
2261 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
2262 { file
= NULL
; dir
= expcerts
; }
2265 file
= expcerts
; dir
= NULL
;
2266 #ifndef DISABLE_OCSP
2267 /* In the server if we will be offering an OCSP proof, load chain from
2268 file for verifying the OCSP proof at load time. */
2271 && statbuf
.st_size
> 0
2272 && server_static_cbinfo
->u_ocsp
.server
.file
2273 && !chain_from_pem_file(file
, server_static_cbinfo
->verify_stack
)
2276 log_write(0, LOG_MAIN
|LOG_PANIC
,
2277 "failed to load cert chain from %s", file
);
2283 /* If a certificate file is empty, the next function fails with an
2284 unhelpful error message. If we skip it, we get the correct behaviour (no
2285 certificates are recognized, but the error message is still misleading (it
2286 says no certificate was supplied). But this is better. */
2288 if ( (!file
|| statbuf
.st_size
> 0)
2289 && !SSL_CTX_load_verify_locations(sctx
, CS file
, CS dir
))
2290 return tls_error(US
"SSL_CTX_load_verify_locations", host
, NULL
, errstr
);
2292 /* Load the list of CAs for which we will accept certs, for sending
2293 to the client. This is only for the one-file tls_verify_certificates
2295 If a list isn't loaded into the server, but some verify locations are set,
2296 the server end appears to make a wildcard request for client certs.
2297 Meanwhile, the client library as default behaviour *ignores* the list
2298 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2299 Because of this, and that the dir variant is likely only used for
2300 the public-CA bundle (not for a private CA), not worth fixing. */
2304 STACK_OF(X509_NAME
) * names
= SSL_load_client_CA_file(CS file
);
2306 SSL_CTX_set_client_CA_list(sctx
, names
);
2307 DEBUG(D_tls
) debug_printf("Added %d certificate authorities.\n",
2308 sk_X509_NAME_num(names
));
2313 /* Handle a certificate revocation list. */
2315 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2317 /* This bit of code is now the version supplied by Lars Mainka. (I have
2318 merely reformatted it into the Exim code style.)
2320 "From here I changed the code to add support for multiple crl's
2321 in pem format in one file or to support hashed directory entries in
2322 pem format instead of a file. This method now uses the library function
2323 X509_STORE_load_locations to add the CRL location to the SSL context.
2324 OpenSSL will then handle the verify against CA certs and CRLs by
2325 itself in the verify callback." */
2327 if (!expand_check(crl
, US
"tls_crl", &expcrl
, errstr
)) return DEFER
;
2328 if (expcrl
&& *expcrl
)
2330 struct stat statbufcrl
;
2331 if (Ustat(expcrl
, &statbufcrl
) < 0)
2333 log_write(0, LOG_MAIN
|LOG_PANIC
,
2334 "failed to stat %s for certificates revocation lists", expcrl
);
2339 /* is it a file or directory? */
2341 X509_STORE
*cvstore
= SSL_CTX_get_cert_store(sctx
);
2342 if ((statbufcrl
.st_mode
& S_IFMT
) == S_IFDIR
)
2346 DEBUG(D_tls
) debug_printf("SSL CRL value is a directory %s\n", dir
);
2352 DEBUG(D_tls
) debug_printf("SSL CRL value is a file %s\n", file
);
2354 if (X509_STORE_load_locations(cvstore
, CS file
, CS dir
) == 0)
2355 return tls_error(US
"X509_STORE_load_locations", host
, NULL
, errstr
);
2357 /* setting the flags to check against the complete crl chain */
2359 X509_STORE_set_flags(cvstore
,
2360 X509_V_FLAG_CRL_CHECK
|X509_V_FLAG_CRL_CHECK_ALL
);
2364 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2366 /* If verification is optional, don't fail if no certificate */
2368 SSL_CTX_set_verify(sctx
,
2369 SSL_VERIFY_PEER
| (optional
? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT
),
2378 /*************************************************
2379 * Start a TLS session in a server *
2380 *************************************************/
2382 /* This is called when Exim is running as a server, after having received
2383 the STARTTLS command. It must respond to that command, and then negotiate
2387 require_ciphers allowed ciphers
2388 errstr pointer to error message
2390 Returns: OK on success
2391 DEFER for errors before the start of the negotiation
2392 FAIL for errors during the negotiation; the server can't
2397 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
2400 uschar
* expciphers
;
2401 tls_ext_ctx_cb
* cbinfo
;
2402 static uschar peerdn
[256];
2404 /* Check for previous activation */
2406 if (tls_in
.active
.sock
>= 0)
2408 tls_error(US
"STARTTLS received after TLS started", NULL
, US
"", errstr
);
2409 smtp_printf("554 Already in TLS\r\n", FALSE
);
2413 /* Initialize the SSL library. If it fails, it will already have logged
2416 rc
= tls_init(&server_ctx
, NULL
, tls_dhparam
, tls_certificate
, tls_privatekey
,
2417 #ifndef DISABLE_OCSP
2418 tls_ocsp_file
, /*XXX stack*/
2420 NULL
, &server_static_cbinfo
, &tls_in
, errstr
);
2421 if (rc
!= OK
) return rc
;
2422 cbinfo
= server_static_cbinfo
;
2424 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
, errstr
))
2427 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2428 were historically separated by underscores. So that I can use either form in my
2429 tests, and also for general convenience, we turn underscores into hyphens here.
2431 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2432 for TLS 1.3 . Since we do not call it at present we get the default list:
2433 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2438 for (uschar
* s
= expciphers
; *s
; s
++ ) if (*s
== '_') *s
= '-';
2439 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2440 if (!SSL_CTX_set_cipher_list(server_ctx
, CS expciphers
))
2441 return tls_error(US
"SSL_CTX_set_cipher_list", NULL
, NULL
, errstr
);
2442 cbinfo
->server_cipher_list
= expciphers
;
2445 /* If this is a host for which certificate verification is mandatory or
2446 optional, set up appropriately. */
2448 tls_in
.certificate_verified
= FALSE
;
2450 tls_in
.dane_verified
= FALSE
;
2452 server_verify_callback_called
= FALSE
;
2454 if (verify_check_host(&tls_verify_hosts
) == OK
)
2456 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
2457 FALSE
, verify_callback_server
, errstr
);
2458 if (rc
!= OK
) return rc
;
2459 server_verify_optional
= FALSE
;
2461 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
2463 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
2464 TRUE
, verify_callback_server
, errstr
);
2465 if (rc
!= OK
) return rc
;
2466 server_verify_optional
= TRUE
;
2469 #ifdef EXPERIMENTAL_TLS_RESUME
2470 SSL_CTX_set_tlsext_ticket_key_cb(server_ctx
, ticket_key_callback
);
2471 /* despite working, appears to always return failure, so ignoring */
2473 #ifdef OPENSSL_HAVE_NUM_TICKETS
2474 # ifdef EXPERIMENTAL_TLS_RESUME
2475 SSL_CTX_set_num_tickets(server_ctx
, tls_in
.host_resumable
? 1 : 0);
2477 SSL_CTX_set_num_tickets(server_ctx
, 0); /* send no TLS1.3 stateful-tickets */
2482 /* Prepare for new connection */
2484 if (!(server_ssl
= SSL_new(server_ctx
)))
2485 return tls_error(US
"SSL_new", NULL
, NULL
, errstr
);
2487 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2489 * With the SSL_clear(), we get strange interoperability bugs with
2490 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2491 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2493 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2494 * session shutdown. In this case, we have a brand new object and there's no
2495 * obvious reason to immediately clear it. I'm guessing that this was
2496 * originally added because of incomplete initialisation which the clear fixed,
2497 * in some historic release.
2500 /* Set context and tell client to go ahead, except in the case of TLS startup
2501 on connection, where outputting anything now upsets the clients and tends to
2502 make them disconnect. We need to have an explicit fflush() here, to force out
2503 the response. Other smtp_printf() calls do not need it, because in non-TLS
2504 mode, the fflush() happens when smtp_getc() is called. */
2506 SSL_set_session_id_context(server_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
2507 if (!tls_in
.on_connect
)
2509 smtp_printf("220 TLS go ahead\r\n", FALSE
);
2513 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2514 that the OpenSSL library doesn't. */
2516 SSL_set_wfd(server_ssl
, fileno(smtp_out
));
2517 SSL_set_rfd(server_ssl
, fileno(smtp_in
));
2518 SSL_set_accept_state(server_ssl
);
2520 DEBUG(D_tls
) debug_printf("Calling SSL_accept\n");
2522 sigalrm_seen
= FALSE
;
2523 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2524 rc
= SSL_accept(server_ssl
);
2529 (void) tls_error(US
"SSL_accept", NULL
, sigalrm_seen
? US
"timed out" : NULL
, errstr
);
2533 DEBUG(D_tls
) debug_printf("SSL_accept was successful\n");
2534 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2535 anon-authentication ciphersuite negotiated. */
2537 #ifdef EXPERIMENTAL_TLS_RESUME
2538 if (SSL_session_reused(server_ssl
))
2540 tls_in
.resumption
|= RESUME_USED
;
2541 DEBUG(D_tls
) debug_printf("Session reused\n");
2545 /* TLS has been set up. Adjust the input functions to read via TLS,
2546 and initialize things. */
2548 peer_cert(server_ssl
, &tls_in
, peerdn
, sizeof(peerdn
));
2550 tls_in
.cipher
= construct_cipher_name(server_ssl
, &tls_in
.bits
);
2551 tls_in
.cipher_stdname
= cipher_stdname_ssl(server_ssl
);
2556 if (SSL_get_shared_ciphers(server_ssl
, CS buf
, sizeof(buf
)))
2557 debug_printf("Shared ciphers: %s\n", buf
);
2559 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
2561 BIO
* bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
2562 SSL_SESSION_print_keylog(bp
, SSL_get_session(server_ssl
));
2567 #ifdef EXIM_HAVE_SESSION_TICKET
2569 SSL_SESSION
* ss
= SSL_get_session(server_ssl
);
2570 if (SSL_SESSION_has_ticket(ss
)) /* 1.1.0 */
2571 debug_printf("The session has a ticket, life %lu seconds\n",
2572 SSL_SESSION_get_ticket_lifetime_hint(ss
));
2577 /* Record the certificate we presented */
2579 X509
* crt
= SSL_get_certificate(server_ssl
);
2580 tls_in
.ourcert
= crt
? X509_dup(crt
) : NULL
;
2583 /* Only used by the server-side tls (tls_in), including tls_getc.
2584 Client-side (tls_out) reads (seem to?) go via
2585 smtp_read_response()/ip_recv().
2586 Hence no need to duplicate for _in and _out.
2588 if (!ssl_xfer_buffer
) ssl_xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2589 ssl_xfer_buffer_lwm
= ssl_xfer_buffer_hwm
= 0;
2590 ssl_xfer_eof
= ssl_xfer_error
= FALSE
;
2592 receive_getc
= tls_getc
;
2593 receive_getbuf
= tls_getbuf
;
2594 receive_get_cache
= tls_get_cache
;
2595 receive_ungetc
= tls_ungetc
;
2596 receive_feof
= tls_feof
;
2597 receive_ferror
= tls_ferror
;
2598 receive_smtp_buffered
= tls_smtp_buffered
;
2600 tls_in
.active
.sock
= fileno(smtp_out
);
2601 tls_in
.active
.tls_ctx
= NULL
; /* not using explicit ctx for server-side */
2609 tls_client_basic_ctx_init(SSL_CTX
* ctx
,
2610 host_item
* host
, smtp_transport_options_block
* ob
, tls_ext_ctx_cb
* cbinfo
,
2614 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2615 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2616 the specified host patterns if one of them is defined */
2618 if ( ( !ob
->tls_verify_hosts
2619 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2621 || verify_check_given_host(CUSS
&ob
->tls_verify_hosts
, host
) == OK
2623 client_verify_optional
= FALSE
;
2624 else if (verify_check_given_host(CUSS
&ob
->tls_try_verify_hosts
, host
) == OK
)
2625 client_verify_optional
= TRUE
;
2629 if ((rc
= setup_certs(ctx
, ob
->tls_verify_certificates
,
2630 ob
->tls_crl
, host
, client_verify_optional
, verify_callback_client
,
2634 if (verify_check_given_host(CUSS
&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2636 cbinfo
->verify_cert_hostnames
=
2638 string_domain_utf8_to_alabel(host
->name
, NULL
);
2642 DEBUG(D_tls
) debug_printf("Cert hostname to check: \"%s\"\n",
2643 cbinfo
->verify_cert_hostnames
);
2651 dane_tlsa_load(SSL
* ssl
, host_item
* host
, dns_answer
* dnsa
, uschar
** errstr
)
2654 const char * hostnames
[2] = { CS host
->name
, NULL
};
2657 if (DANESSL_init(ssl
, NULL
, hostnames
) != 1)
2658 return tls_error(US
"hostnames load", host
, NULL
, errstr
);
2660 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2661 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2662 ) if (rr
->type
== T_TLSA
&& rr
->size
> 3)
2664 const uschar
* p
= rr
->data
;
2665 uint8_t usage
, selector
, mtype
;
2666 const char * mdname
;
2670 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2671 if (usage
!= 2 && usage
!= 3) continue;
2678 default: continue; /* Only match-types 0, 1, 2 are supported */
2679 case 0: mdname
= NULL
; break;
2680 case 1: mdname
= "sha256"; break;
2681 case 2: mdname
= "sha512"; break;
2685 switch (DANESSL_add_tlsa(ssl
, usage
, selector
, mdname
, p
, rr
->size
- 3))
2688 return tls_error(US
"tlsa load", host
, NULL
, errstr
);
2689 case 0: /* action not taken */
2693 tls_out
.tlsa_usage
|= 1<<usage
;
2699 log_write(0, LOG_MAIN
, "DANE error: No usable TLSA records");
2702 #endif /*SUPPORT_DANE*/
2706 #ifdef EXPERIMENTAL_TLS_RESUME
2707 /* On the client, get any stashed session for the given IP from hints db
2708 and apply it to the ssl-connection for attempted resumption. */
2711 tls_retrieve_session(tls_support
* tlsp
, SSL
* ssl
, const uschar
* key
)
2713 tlsp
->resumption
|= RESUME_SUPPORTED
;
2714 if (tlsp
->host_resumable
)
2716 dbdata_tls_session
* dt
;
2718 open_db dbblock
, * dbm_file
;
2720 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
2721 DEBUG(D_tls
) debug_printf("checking for resumable session for %s\n", key
);
2722 if ((dbm_file
= dbfn_open(US
"tls", O_RDONLY
, &dbblock
, FALSE
, FALSE
)))
2724 /* key for the db is the IP */
2725 if ((dt
= dbfn_read_with_length(dbm_file
, key
, &len
)))
2727 SSL_SESSION
* ss
= NULL
;
2728 const uschar
* sess_asn1
= dt
->session
;
2730 len
-= sizeof(dbdata_tls_session
);
2731 if (!(d2i_SSL_SESSION(&ss
, &sess_asn1
, (long)len
)))
2735 ERR_error_string_n(ERR_get_error(),
2736 ssl_errstring
, sizeof(ssl_errstring
));
2737 debug_printf("decoding session: %s\n", ssl_errstring
);
2740 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss
) + dt
->time_stamp
2743 DEBUG(D_tls
) debug_printf("session expired\n");
2744 dbfn_delete(dbm_file
, key
);
2746 else if (!SSL_set_session(ssl
, ss
))
2750 ERR_error_string_n(ERR_get_error(),
2751 ssl_errstring
, sizeof(ssl_errstring
));
2752 debug_printf("applying session to ssl: %s\n", ssl_errstring
);
2757 DEBUG(D_tls
) debug_printf("good session\n");
2758 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
2762 DEBUG(D_tls
) debug_printf("no session record\n");
2763 dbfn_close(dbm_file
);
2769 /* On the client, save the session for later resumption */
2772 tls_save_session_cb(SSL
* ssl
, SSL_SESSION
* ss
)
2774 tls_ext_ctx_cb
* cbinfo
= SSL_get_ex_data(ssl
, tls_exdata_idx
);
2777 DEBUG(D_tls
) debug_printf("tls_save_session_cb\n");
2779 if (!cbinfo
|| !(tlsp
= cbinfo
->tlsp
)->host_resumable
) return 0;
2781 # ifdef OPENSSL_HAVE_NUM_TICKETS
2782 if (SSL_SESSION_is_resumable(ss
)) /* 1.1.1 */
2785 int len
= i2d_SSL_SESSION(ss
, NULL
);
2786 int dlen
= sizeof(dbdata_tls_session
) + len
;
2787 dbdata_tls_session
* dt
= store_get(dlen
);
2788 uschar
* s
= dt
->session
;
2789 open_db dbblock
, * dbm_file
;
2791 DEBUG(D_tls
) debug_printf("session is resumable\n");
2792 tlsp
->resumption
|= RESUME_SERVER_TICKET
; /* server gave us a ticket */
2794 len
= i2d_SSL_SESSION(ss
, &s
); /* s gets bumped to end */
2796 if ((dbm_file
= dbfn_open(US
"tls", O_RDWR
, &dbblock
, FALSE
, FALSE
)))
2798 const uschar
* key
= cbinfo
->host
->address
;
2799 dbfn_delete(dbm_file
, key
);
2800 dbfn_write(dbm_file
, key
, dt
, dlen
);
2801 dbfn_close(dbm_file
);
2802 DEBUG(D_tls
) debug_printf("wrote session (len %u) to db\n",
2811 tls_client_ctx_resume_prehandshake(
2812 exim_openssl_client_tls_ctx
* exim_client_ctx
, tls_support
* tlsp
,
2813 smtp_transport_options_block
* ob
, host_item
* host
)
2815 /* Should the client request a session resumption ticket? */
2816 if (verify_check_given_host(CUSS
&ob
->tls_resumption_hosts
, host
) == OK
)
2818 tlsp
->host_resumable
= TRUE
;
2820 SSL_CTX_set_session_cache_mode(exim_client_ctx
->ctx
,
2821 SSL_SESS_CACHE_CLIENT
2822 | SSL_SESS_CACHE_NO_INTERNAL
| SSL_SESS_CACHE_NO_AUTO_CLEAR
);
2823 SSL_CTX_sess_set_new_cb(exim_client_ctx
->ctx
, tls_save_session_cb
);
2828 tls_client_ssl_resume_prehandshake(SSL
* ssl
, tls_support
* tlsp
,
2829 host_item
* host
, uschar
** errstr
)
2831 if (tlsp
->host_resumable
)
2834 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
2835 SSL_clear_options(ssl
, SSL_OP_NO_TICKET
);
2837 tls_exdata_idx
= SSL_get_ex_new_index(0, 0, 0, 0, 0);
2838 if (!SSL_set_ex_data(ssl
, tls_exdata_idx
, client_static_cbinfo
))
2840 tls_error(US
"set ex_data", host
, NULL
, errstr
);
2843 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx
, client_static_cbinfo
);
2846 tlsp
->resumption
= RESUME_SUPPORTED
;
2847 /* Pick up a previous session, saved on an old ticket */
2848 tls_retrieve_session(tlsp
, ssl
, host
->address
);
2853 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx
* exim_client_ctx
,
2856 if (SSL_session_reused(exim_client_ctx
->ssl
))
2858 DEBUG(D_tls
) debug_printf("The session was reused\n");
2859 tlsp
->resumption
|= RESUME_USED
;
2862 #endif /* EXPERIMENTAL_TLS_RESUME */
2865 /*************************************************
2866 * Start a TLS session in a client *
2867 *************************************************/
2869 /* Called from the smtp transport after STARTTLS has been accepted.
2872 cctx connection context
2873 conn_args connection details
2874 cookie datum for randomness; can be NULL
2875 tlsp record details of TLS channel configuration here; must be non-NULL
2876 errstr error string pointer
2878 Returns: TRUE for success with TLS session context set in connection context,
2883 tls_client_start(client_conn_ctx
* cctx
, smtp_connect_args
* conn_args
,
2884 void * cookie
, tls_support
* tlsp
, uschar
** errstr
)
2886 host_item
* host
= conn_args
->host
; /* for msgs and option-tests */
2887 transport_instance
* tb
= conn_args
->tblock
; /* always smtp or NULL */
2888 smtp_transport_options_block
* ob
= tb
2889 ? (smtp_transport_options_block
*)tb
->options_block
2890 : &smtp_transport_option_defaults
;
2891 exim_openssl_client_tls_ctx
* exim_client_ctx
;
2892 uschar
* expciphers
;
2894 static uschar peerdn
[256];
2896 #ifndef DISABLE_OCSP
2897 BOOL request_ocsp
= FALSE
;
2898 BOOL require_ocsp
= FALSE
;
2902 store_pool
= POOL_PERM
;
2903 exim_client_ctx
= store_get(sizeof(exim_openssl_client_tls_ctx
));
2904 exim_client_ctx
->corked
= NULL
;
2908 tlsp
->tlsa_usage
= 0;
2911 #ifndef DISABLE_OCSP
2913 # ifdef SUPPORT_DANE
2914 if ( conn_args
->dane
2915 && ob
->hosts_request_ocsp
[0] == '*'
2916 && ob
->hosts_request_ocsp
[1] == '\0'
2919 /* Unchanged from default. Use a safer one under DANE */
2920 request_ocsp
= TRUE
;
2921 ob
->hosts_request_ocsp
= US
"${if or { {= {0}{$tls_out_tlsa_usage}} "
2922 " {= {4}{$tls_out_tlsa_usage}} } "
2928 verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
))
2929 request_ocsp
= TRUE
;
2931 # ifdef SUPPORT_DANE
2935 verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2939 rc
= tls_init(&exim_client_ctx
->ctx
, host
, NULL
,
2940 ob
->tls_certificate
, ob
->tls_privatekey
,
2941 #ifndef DISABLE_OCSP
2942 (void *)(long)request_ocsp
,
2944 cookie
, &client_static_cbinfo
, tlsp
, errstr
);
2945 if (rc
!= OK
) return FALSE
;
2947 tlsp
->certificate_verified
= FALSE
;
2948 client_verify_callback_called
= FALSE
;
2952 if (conn_args
->dane
)
2954 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2955 other failures should be treated as problems. */
2956 if (ob
->dane_require_tls_ciphers
&&
2957 !expand_check(ob
->dane_require_tls_ciphers
, US
"dane_require_tls_ciphers",
2958 &expciphers
, errstr
))
2960 if (expciphers
&& *expciphers
== '\0')
2965 !expand_check(ob
->tls_require_ciphers
, US
"tls_require_ciphers",
2966 &expciphers
, errstr
))
2969 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2970 are separated by underscores. So that I can use either form in my tests, and
2971 also for general convenience, we turn underscores into hyphens here. */
2975 uschar
*s
= expciphers
;
2976 while (*s
) { if (*s
== '_') *s
= '-'; s
++; }
2977 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2978 if (!SSL_CTX_set_cipher_list(exim_client_ctx
->ctx
, CS expciphers
))
2980 tls_error(US
"SSL_CTX_set_cipher_list", host
, NULL
, errstr
);
2986 if (conn_args
->dane
)
2988 SSL_CTX_set_verify(exim_client_ctx
->ctx
,
2989 SSL_VERIFY_PEER
| SSL_VERIFY_FAIL_IF_NO_PEER_CERT
,
2990 verify_callback_client_dane
);
2992 if (!DANESSL_library_init())
2994 tls_error(US
"library init", host
, NULL
, errstr
);
2997 if (DANESSL_CTX_init(exim_client_ctx
->ctx
) <= 0)
2999 tls_error(US
"context init", host
, NULL
, errstr
);
3007 if (tls_client_basic_ctx_init(exim_client_ctx
->ctx
, host
, ob
,
3008 client_static_cbinfo
, errstr
) != OK
)
3011 #ifdef EXPERIMENTAL_TLS_RESUME
3012 tls_client_ctx_resume_prehandshake(exim_client_ctx
, tlsp
, ob
, host
);
3016 if (!(exim_client_ctx
->ssl
= SSL_new(exim_client_ctx
->ctx
)))
3018 tls_error(US
"SSL_new", host
, NULL
, errstr
);
3021 SSL_set_session_id_context(exim_client_ctx
->ssl
, sid_ctx
, Ustrlen(sid_ctx
));
3023 #ifdef EXPERIMENTAL_TLS_RESUME
3024 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx
->ssl
, tlsp
, host
,
3029 SSL_set_fd(exim_client_ctx
->ssl
, cctx
->sock
);
3030 SSL_set_connect_state(exim_client_ctx
->ssl
);
3034 if (!expand_check(ob
->tls_sni
, US
"tls_sni", &tlsp
->sni
, errstr
))
3038 DEBUG(D_tls
) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3040 else if (!Ustrlen(tlsp
->sni
))
3044 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3045 DEBUG(D_tls
) debug_printf("Setting TLS SNI \"%s\"\n", tlsp
->sni
);
3046 SSL_set_tlsext_host_name(exim_client_ctx
->ssl
, tlsp
->sni
);
3048 log_write(0, LOG_MAIN
, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3055 if (conn_args
->dane
)
3056 if (dane_tlsa_load(exim_client_ctx
->ssl
, host
, &conn_args
->tlsa_dnsa
, errstr
) != OK
)
3060 #ifndef DISABLE_OCSP
3061 /* Request certificate status at connection-time. If the server
3062 does OCSP stapling we will get the callback (set in tls_init()) */
3063 # ifdef SUPPORT_DANE
3067 if ( ((s
= ob
->hosts_require_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
3068 || ((s
= ob
->hosts_request_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
3070 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3071 this means we avoid the OCSP request, we wasted the setup
3072 cost in tls_init(). */
3073 require_ocsp
= verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
;
3074 request_ocsp
= require_ocsp
3075 || verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
3082 SSL_set_tlsext_status_type(exim_client_ctx
->ssl
, TLSEXT_STATUSTYPE_ocsp
);
3083 client_static_cbinfo
->u_ocsp
.client
.verify_required
= require_ocsp
;
3084 tlsp
->ocsp
= OCSP_NOT_RESP
;
3088 #ifndef DISABLE_EVENT
3089 client_static_cbinfo
->event_action
= tb
? tb
->event_action
: NULL
;
3092 /* There doesn't seem to be a built-in timeout on connection. */
3094 DEBUG(D_tls
) debug_printf("Calling SSL_connect\n");
3095 sigalrm_seen
= FALSE
;
3096 ALARM(ob
->command_timeout
);
3097 rc
= SSL_connect(exim_client_ctx
->ssl
);
3101 if (conn_args
->dane
)
3102 DANESSL_cleanup(exim_client_ctx
->ssl
);
3107 tls_error(US
"SSL_connect", host
, sigalrm_seen
? US
"timed out" : NULL
, errstr
);
3113 debug_printf("SSL_connect succeeded\n");
3114 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3116 BIO
* bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
3117 SSL_SESSION_print_keylog(bp
, SSL_get_session(exim_client_ctx
->ssl
));
3123 #ifdef EXPERIMENTAL_TLS_RESUME
3124 tls_client_resume_posthandshake(exim_client_ctx
, tlsp
);
3127 peer_cert(exim_client_ctx
->ssl
, tlsp
, peerdn
, sizeof(peerdn
));
3129 tlsp
->cipher
= construct_cipher_name(exim_client_ctx
->ssl
, &tlsp
->bits
);
3130 tlsp
->cipher_stdname
= cipher_stdname_ssl(exim_client_ctx
->ssl
);
3132 /* Record the certificate we presented */
3134 X509
* crt
= SSL_get_certificate(exim_client_ctx
->ssl
);
3135 tlsp
->ourcert
= crt
? X509_dup(crt
) : NULL
;
3138 tlsp
->active
.sock
= cctx
->sock
;
3139 tlsp
->active
.tls_ctx
= exim_client_ctx
;
3140 cctx
->tls_ctx
= exim_client_ctx
;
3149 tls_refill(unsigned lim
)
3154 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl
,
3155 ssl_xfer_buffer
, ssl_xfer_buffer_size
);
3157 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
3158 inbytes
= SSL_read(server_ssl
, CS ssl_xfer_buffer
,
3159 MIN(ssl_xfer_buffer_size
, lim
));
3160 error
= SSL_get_error(server_ssl
, inbytes
);
3161 if (smtp_receive_timeout
> 0) ALARM_CLR(0);
3163 if (had_command_timeout
) /* set by signal handler */
3164 smtp_command_timeout_exit(); /* does not return */
3165 if (had_command_sigterm
)
3166 smtp_command_sigterm_exit();
3167 if (had_data_timeout
)
3168 smtp_data_timeout_exit();
3169 if (had_data_sigint
)
3170 smtp_data_sigint_exit();
3172 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3173 closed down, not that the socket itself has been closed down. Revert to
3174 non-SSL handling. */
3178 case SSL_ERROR_NONE
:
3181 case SSL_ERROR_ZERO_RETURN
:
3182 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3184 receive_getc
= smtp_getc
;
3185 receive_getbuf
= smtp_getbuf
;
3186 receive_get_cache
= smtp_get_cache
;
3187 receive_ungetc
= smtp_ungetc
;
3188 receive_feof
= smtp_feof
;
3189 receive_ferror
= smtp_ferror
;
3190 receive_smtp_buffered
= smtp_buffered
;
3192 if (SSL_get_shutdown(server_ssl
) == SSL_RECEIVED_SHUTDOWN
)
3193 SSL_shutdown(server_ssl
);
3195 #ifndef DISABLE_OCSP
3196 sk_X509_pop_free(server_static_cbinfo
->verify_stack
, X509_free
);
3197 server_static_cbinfo
->verify_stack
= NULL
;
3199 SSL_free(server_ssl
);
3200 SSL_CTX_free(server_ctx
);
3203 tls_in
.active
.sock
= -1;
3204 tls_in
.active
.tls_ctx
= NULL
;
3206 tls_in
.cipher
= NULL
;
3207 tls_in
.peerdn
= NULL
;
3212 /* Handle genuine errors */
3214 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3215 log_write(0, LOG_MAIN
, "TLS error (SSL_read): %s", ssl_errstring
);
3216 ssl_xfer_error
= TRUE
;
3220 DEBUG(D_tls
) debug_printf("Got SSL error %d\n", error
);
3221 DEBUG(D_tls
) if (error
== SSL_ERROR_SYSCALL
)
3222 debug_printf(" - syscall %s\n", strerror(errno
));
3223 ssl_xfer_error
= TRUE
;
3227 #ifndef DISABLE_DKIM
3228 dkim_exim_verify_feed(ssl_xfer_buffer
, inbytes
);
3230 ssl_xfer_buffer_hwm
= inbytes
;
3231 ssl_xfer_buffer_lwm
= 0;
3236 /*************************************************
3237 * TLS version of getc *
3238 *************************************************/
3240 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3241 it refills the buffer via the SSL reading function.
3243 Arguments: lim Maximum amount to read/buffer
3244 Returns: the next character or EOF
3246 Only used by the server-side TLS.
3250 tls_getc(unsigned lim
)
3252 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
3253 if (!tls_refill(lim
))
3254 return ssl_xfer_error
? EOF
: smtp_getc(lim
);
3256 /* Something in the buffer; return next uschar */
3258 return ssl_xfer_buffer
[ssl_xfer_buffer_lwm
++];
3262 tls_getbuf(unsigned * len
)
3267 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
3268 if (!tls_refill(*len
))
3270 if (!ssl_xfer_error
) return smtp_getbuf(len
);
3275 if ((size
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
) > *len
)
3277 buf
= &ssl_xfer_buffer
[ssl_xfer_buffer_lwm
];
3278 ssl_xfer_buffer_lwm
+= size
;
3287 #ifndef DISABLE_DKIM
3288 int n
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
;
3290 dkim_exim_verify_feed(ssl_xfer_buffer
+ssl_xfer_buffer_lwm
, n
);
3296 tls_could_read(void)
3298 return ssl_xfer_buffer_lwm
< ssl_xfer_buffer_hwm
|| SSL_pending(server_ssl
) > 0;
3302 /*************************************************
3303 * Read bytes from TLS channel *
3304 *************************************************/
3308 ct_ctx client context pointer, or NULL for the one global server context
3312 Returns: the number of bytes read
3313 -1 after a failed read, including EOF
3315 Only used by the client-side TLS.
3319 tls_read(void * ct_ctx
, uschar
*buff
, size_t len
)
3321 SSL
* ssl
= ct_ctx
? ((exim_openssl_client_tls_ctx
*)ct_ctx
)->ssl
: server_ssl
;
3325 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl
,
3326 buff
, (unsigned int)len
);
3328 inbytes
= SSL_read(ssl
, CS buff
, len
);
3329 error
= SSL_get_error(ssl
, inbytes
);
3331 if (error
== SSL_ERROR_ZERO_RETURN
)
3333 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3336 else if (error
!= SSL_ERROR_NONE
)
3346 /*************************************************
3347 * Write bytes down TLS channel *
3348 *************************************************/
3352 ct_ctx client context pointer, or NULL for the one global server context
3355 more further data expected soon
3357 Returns: the number of bytes after a successful write,
3358 -1 after a failed write
3360 Used by both server-side and client-side TLS.
3364 tls_write(void * ct_ctx
, const uschar
*buff
, size_t len
, BOOL more
)
3367 int outbytes
, error
;
3369 ? ((exim_openssl_client_tls_ctx
*)ct_ctx
)->ssl
: server_ssl
;
3370 static gstring
* server_corked
= NULL
;
3371 gstring
** corkedp
= ct_ctx
3372 ? &((exim_openssl_client_tls_ctx
*)ct_ctx
)->corked
: &server_corked
;
3373 gstring
* corked
= *corkedp
;
3375 DEBUG(D_tls
) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__
,
3376 buff
, (unsigned long)len
, more
? ", more" : "");
3378 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
3379 "more" is notified. This hack is only ok if small amounts are involved AND only
3380 one stream does it, in one context (i.e. no store reset). Currently it is used
3381 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
3382 We support callouts done by the server process by using a separate client
3383 context for the stashed information. */
3384 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
3385 a store reset there, so use POOL_PERM. */
3386 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
3388 if ((more
|| corked
))
3390 #ifdef EXPERIMENTAL_PIPE_CONNECT
3391 int save_pool
= store_pool
;
3392 store_pool
= POOL_PERM
;
3395 corked
= string_catn(corked
, buff
, len
);
3397 #ifdef EXPERIMENTAL_PIPE_CONNECT
3398 store_pool
= save_pool
;
3406 buff
= CUS corked
->s
;
3411 for (int left
= len
; left
> 0;)
3413 DEBUG(D_tls
) debug_printf("SSL_write(%p, %p, %d)\n", ssl
, buff
, left
);
3414 outbytes
= SSL_write(ssl
, CS buff
, left
);
3415 error
= SSL_get_error(ssl
, outbytes
);
3416 DEBUG(D_tls
) debug_printf("outbytes=%d error=%d\n", outbytes
, error
);
3420 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3421 log_write(0, LOG_MAIN
, "TLS error (SSL_write): %s", ssl_errstring
);
3424 case SSL_ERROR_NONE
:
3429 case SSL_ERROR_ZERO_RETURN
:
3430 log_write(0, LOG_MAIN
, "SSL channel closed on write");
3433 case SSL_ERROR_SYSCALL
:
3434 log_write(0, LOG_MAIN
, "SSL_write: (from %s) syscall: %s",
3435 sender_fullhost
? sender_fullhost
: US
"<unknown>",
3440 log_write(0, LOG_MAIN
, "SSL_write error %d", error
);
3449 /*************************************************
3450 * Close down a TLS session *
3451 *************************************************/
3453 /* This is also called from within a delivery subprocess forked from the
3454 daemon, to shut down the TLS library, without actually doing a shutdown (which
3455 would tamper with the SSL session in the parent process).
3458 ct_ctx client TLS context pointer, or NULL for the one global server context
3459 shutdown 1 if TLS close-alert is to be sent,
3460 2 if also response to be waited for
3464 Used by both server-side and client-side TLS.
3468 tls_close(void * ct_ctx
, int shutdown
)
3470 exim_openssl_client_tls_ctx
* o_ctx
= ct_ctx
;
3471 SSL_CTX
**ctxp
= o_ctx
? &o_ctx
->ctx
: &server_ctx
;
3472 SSL
**sslp
= o_ctx
? &o_ctx
->ssl
: &server_ssl
;
3473 int *fdp
= o_ctx
? &tls_out
.active
.sock
: &tls_in
.active
.sock
;
3475 if (*fdp
< 0) return; /* TLS was not active */
3480 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS%s\n",
3481 shutdown
> 1 ? " (with response-wait)" : "");
3483 if ( (rc
= SSL_shutdown(*sslp
)) == 0 /* send "close notify" alert */
3487 rc
= SSL_shutdown(*sslp
); /* wait for response */
3491 if (rc
< 0) DEBUG(D_tls
)
3493 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3494 debug_printf("SSL_shutdown: %s\n", ssl_errstring
);
3498 #ifndef DISABLE_OCSP
3499 if (!o_ctx
) /* server side */
3501 sk_X509_pop_free(server_static_cbinfo
->verify_stack
, X509_free
);
3502 server_static_cbinfo
->verify_stack
= NULL
;
3506 SSL_CTX_free(*ctxp
);
3516 /*************************************************
3517 * Let tls_require_ciphers be checked at startup *
3518 *************************************************/
3520 /* The tls_require_ciphers option, if set, must be something which the
3523 Returns: NULL on success, or error message
3527 tls_validate_require_cipher(void)
3530 uschar
*s
, *expciphers
, *err
;
3532 /* this duplicates from tls_init(), we need a better "init just global
3533 state, for no specific purpose" singleton function of our own */
3535 #ifdef EXIM_NEED_OPENSSL_INIT
3536 SSL_load_error_strings();
3537 OpenSSL_add_ssl_algorithms();
3539 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
3540 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
3541 list of available digests. */
3542 EVP_add_digest(EVP_sha256());
3545 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
3548 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
3550 return US
"failed to expand tls_require_ciphers";
3552 if (!(expciphers
&& *expciphers
))
3555 /* normalisation ripped from above */
3557 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
3561 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3562 if (!(ctx
= SSL_CTX_new(TLS_server_method())))
3564 if (!(ctx
= SSL_CTX_new(SSLv23_server_method())))
3567 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3568 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring
);
3572 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
3574 if (!SSL_CTX_set_cipher_list(ctx
, CS expciphers
))
3576 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3577 err
= string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3578 expciphers
, ssl_errstring
);
3589 /*************************************************
3590 * Report the library versions. *
3591 *************************************************/
3593 /* There have historically been some issues with binary compatibility in
3594 OpenSSL libraries; if Exim (like many other applications) is built against
3595 one version of OpenSSL but the run-time linker picks up another version,
3596 it can result in serious failures, including crashing with a SIGSEGV. So
3597 report the version found by the compiler and the run-time version.
3599 Note: some OS vendors backport security fixes without changing the version
3600 number/string, and the version date remains unchanged. The _build_ date
3601 will change, so we can more usefully assist with version diagnosis by also
3602 reporting the build date.
3604 Arguments: a FILE* to print the results to
3609 tls_version_report(FILE *f
)
3611 fprintf(f
, "Library version: OpenSSL: Compile: %s\n"
3614 OPENSSL_VERSION_TEXT
,
3615 SSLeay_version(SSLEAY_VERSION
),
3616 SSLeay_version(SSLEAY_BUILT_ON
));
3617 /* third line is 38 characters for the %s and the line is 73 chars long;
3618 the OpenSSL output includes a "built on: " prefix already. */
3624 /*************************************************
3625 * Random number generation *
3626 *************************************************/
3628 /* Pseudo-random number generation. The result is not expected to be
3629 cryptographically strong but not so weak that someone will shoot themselves
3630 in the foot using it as a nonce in input in some email header scheme or
3631 whatever weirdness they'll twist this into. The result should handle fork()
3632 and avoid repeating sequences. OpenSSL handles that for us.
3636 Returns a random number in range [0, max-1]
3640 vaguely_random_number(int max
)
3644 static pid_t pidlast
= 0;
3646 uschar smallbuf
[sizeof(r
)];
3652 if (pidnow
!= pidlast
)
3654 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3655 is unique for each thread", this doesn't apparently apply across processes,
3656 so our own warning from vaguely_random_number_fallback() applies here too.
3657 Fix per PostgreSQL. */
3663 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3667 gettimeofday(&r
.tv
, NULL
);
3670 RAND_seed(US (&r
), sizeof(r
));
3672 /* We're after pseudo-random, not random; if we still don't have enough data
3673 in the internal PRNG then our options are limited. We could sleep and hope
3674 for entropy to come along (prayer technique) but if the system is so depleted
3675 in the first place then something is likely to just keep taking it. Instead,
3676 we'll just take whatever little bit of pseudo-random we can still manage to
3679 needed_len
= sizeof(r
);
3680 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3681 asked for a number less than 10. */
3682 for (r
= max
, i
= 0; r
; ++i
)
3688 #ifdef EXIM_HAVE_RAND_PSEUDO
3689 /* We do not care if crypto-strong */
3690 i
= RAND_pseudo_bytes(smallbuf
, needed_len
);
3692 i
= RAND_bytes(smallbuf
, needed_len
);
3698 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3699 return vaguely_random_number_fallback(max
);
3703 for (uschar
* p
= smallbuf
; needed_len
; --needed_len
, ++p
)
3706 /* We don't particularly care about weighted results; if someone wants
3707 smooth distribution and cares enough then they should submit a patch then. */
3714 /*************************************************
3715 * OpenSSL option parse *
3716 *************************************************/
3718 /* Parse one option for tls_openssl_options_parse below
3721 name one option name
3722 value place to store a value for it
3723 Returns success or failure in parsing
3729 tls_openssl_one_option_parse(uschar
*name
, long *value
)
3732 int last
= exim_openssl_options_size
;
3733 while (last
> first
)
3735 int middle
= (first
+ last
)/2;
3736 int c
= Ustrcmp(name
, exim_openssl_options
[middle
].name
);
3739 *value
= exim_openssl_options
[middle
].value
;
3753 /*************************************************
3754 * OpenSSL option parsing logic *
3755 *************************************************/
3757 /* OpenSSL has a number of compatibility options which an administrator might
3758 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3759 we look like log_selector.
3762 option_spec the administrator-supplied string of options
3763 results ptr to long storage for the options bitmap
3764 Returns success or failure
3768 tls_openssl_options_parse(uschar
*option_spec
, long *results
)
3773 BOOL adding
, item_parsed
;
3775 /* Server: send no (<= TLS1.2) session tickets */
3776 result
= SSL_OP_NO_TICKET
;
3778 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3779 * from default because it increases BEAST susceptibility. */
3780 #ifdef SSL_OP_NO_SSLv2
3781 result
|= SSL_OP_NO_SSLv2
;
3783 #ifdef SSL_OP_NO_SSLv3
3784 result
|= SSL_OP_NO_SSLv3
;
3786 #ifdef SSL_OP_SINGLE_DH_USE
3787 result
|= SSL_OP_SINGLE_DH_USE
;
3796 for (uschar
* s
= option_spec
; *s
; /**/)
3798 while (isspace(*s
)) ++s
;
3801 if (*s
!= '+' && *s
!= '-')
3803 DEBUG(D_tls
) debug_printf("malformed openssl option setting: "
3804 "+ or - expected but found \"%s\"\n", s
);
3807 adding
= *s
++ == '+';
3808 for (end
= s
; (*end
!= '\0') && !isspace(*end
); ++end
) /**/ ;
3811 item_parsed
= tls_openssl_one_option_parse(s
, &item
);
3815 DEBUG(D_tls
) debug_printf("openssl option setting unrecognised: \"%s\"\n", s
);
3818 DEBUG(D_tls
) debug_printf("openssl option, %s %8lx: %lx (%s)\n",
3819 adding
? "adding to " : "removing from", result
, item
, s
);
3831 #endif /*!MACRO_PREDEF*/
3834 /* End of tls-openssl.c */