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", (long) 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 tlsp
->verify_override
= FALSE
;
590 if (preverify_ok
== 0)
592 uschar
* extra
= verify_mode
? string_sprintf(" (during %c-verify for [%s])",
593 *verify_mode
, sender_host_address
)
595 log_write(0, LOG_MAIN
, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
596 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
598 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx
)), dn
);
603 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
604 return 0; /* reject */
606 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
607 "tls_try_verify_hosts)\n");
608 tlsp
->verify_override
= TRUE
;
613 DEBUG(D_tls
) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth
, dn
);
615 if (tlsp
== &tls_out
&& client_static_cbinfo
->u_ocsp
.client
.verify_store
)
616 { /* client, wanting stapling */
617 /* Add the server cert's signing chain as the one
618 for the verification of the OCSP stapled information. */
620 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
623 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
626 #ifndef DISABLE_EVENT
627 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
628 return 0; /* reject, with peercert set */
633 const uschar
* verify_cert_hostnames
;
635 if ( tlsp
== &tls_out
636 && ((verify_cert_hostnames
= client_static_cbinfo
->verify_cert_hostnames
)))
637 /* client, wanting hostname check */
640 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
641 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
642 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
644 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
645 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
648 const uschar
* list
= verify_cert_hostnames
;
651 while ((name
= string_nextinlist(&list
, &sep
, NULL
, 0)))
652 if ((rc
= X509_check_host(cert
, CCS name
, 0,
653 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
654 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
,
659 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
660 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
);
667 if (!tls_is_name_for_cert(verify_cert_hostnames
, cert
))
670 uschar
* extra
= verify_mode
671 ? string_sprintf(" (during %c-verify for [%s])",
672 *verify_mode
, sender_host_address
)
674 log_write(0, LOG_MAIN
,
675 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
676 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
677 extra
, dn
, verify_cert_hostnames
);
682 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
683 return 0; /* reject */
685 DEBUG(D_tls
) debug_printf("SSL verify name failure overridden (host in "
686 "tls_try_verify_hosts)\n");
687 tlsp
->verify_override
= TRUE
;
691 #ifndef DISABLE_EVENT
692 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
693 return 0; /* reject, with peercert set */
696 DEBUG(D_tls
) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
697 *calledp
? "" : " authenticated", dn
);
701 return 1; /* accept, at least for this level */
705 verify_callback_client(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
707 return verify_callback(preverify_ok
, x509ctx
, &tls_out
,
708 &client_verify_callback_called
, &client_verify_optional
);
712 verify_callback_server(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
714 return verify_callback(preverify_ok
, x509ctx
, &tls_in
,
715 &server_verify_callback_called
, &server_verify_optional
);
721 /* This gets called *by* the dane library verify callback, which interposes
725 verify_callback_client_dane(int preverify_ok
, X509_STORE_CTX
* x509ctx
)
727 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
729 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
730 #ifndef DISABLE_EVENT
731 BOOL dummy_called
, optional
= FALSE
;
734 if (!X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
)))
736 DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n");
737 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
738 deliver_host_address
);
741 dn
[sizeof(dn
)-1] = '\0';
743 DEBUG(D_tls
) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
744 preverify_ok
? "ok":"BAD", depth
, dn
);
746 #ifndef DISABLE_EVENT
747 if (verify_event(&tls_out
, cert
, depth
, dn
,
748 &dummy_called
, &optional
, US
"DANE"))
749 return 0; /* reject, with peercert set */
752 if (preverify_ok
== 1)
754 tls_out
.dane_verified
= TRUE
;
756 if (client_static_cbinfo
->u_ocsp
.client
.verify_store
)
757 { /* client, wanting stapling */
758 /* Add the server cert's signing chain as the one
759 for the verification of the OCSP stapled information. */
761 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
764 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
770 int err
= X509_STORE_CTX_get_error(x509ctx
);
772 debug_printf(" - err %d '%s'\n", err
, X509_verify_cert_error_string(err
));
773 if (err
== X509_V_ERR_APPLICATION_VERIFICATION
)
779 #endif /*SUPPORT_DANE*/
782 /*************************************************
783 * Information callback *
784 *************************************************/
786 /* The SSL library functions call this from time to time to indicate what they
787 are doing. We copy the string to the debugging output when TLS debugging has
799 info_callback(SSL
*s
, int where
, int ret
)
805 if (where
& SSL_ST_CONNECT
)
806 str
= US
"SSL_connect";
807 else if (where
& SSL_ST_ACCEPT
)
808 str
= US
"SSL_accept";
810 str
= US
"SSL info (undefined)";
812 if (where
& SSL_CB_LOOP
)
813 debug_printf("%s: %s\n", str
, SSL_state_string_long(s
));
814 else if (where
& SSL_CB_ALERT
)
815 debug_printf("SSL3 alert %s:%s:%s\n",
816 str
= where
& SSL_CB_READ
? US
"read" : US
"write",
817 SSL_alert_type_string_long(ret
), SSL_alert_desc_string_long(ret
));
818 else if (where
& SSL_CB_EXIT
)
820 debug_printf("%s: failed in %s\n", str
, SSL_state_string_long(s
));
822 debug_printf("%s: error in %s\n", str
, SSL_state_string_long(s
));
823 else if (where
& SSL_CB_HANDSHAKE_START
)
824 debug_printf("%s: hshake start: %s\n", str
, SSL_state_string_long(s
));
825 else if (where
& SSL_CB_HANDSHAKE_DONE
)
826 debug_printf("%s: hshake done: %s\n", str
, SSL_state_string_long(s
));
830 #ifdef OPENSSL_HAVE_KEYLOG_CB
832 keylog_callback(const SSL
*ssl
, const char *line
)
834 DEBUG(D_tls
) debug_printf("%.200s\n", line
);
839 #ifdef EXPERIMENTAL_TLS_RESUME
840 /* Manage the keysets used for encrypting the session tickets, on the server. */
842 typedef struct { /* Session ticket encryption key */
845 const EVP_CIPHER
* aes_cipher
;
846 uschar aes_key
[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
847 const EVP_MD
* hmac_hash
;
853 static exim_stek exim_tk
; /* current key */
854 static exim_stek exim_tk_old
; /* previous key */
859 time_t t
= time(NULL
);
863 if (exim_tk
.renew
>= t
) return;
864 exim_tk_old
= exim_tk
;
867 if (f
.running_in_test_harness
) ssl_session_timeout
= 6;
869 DEBUG(D_tls
) debug_printf("OpenSSL: %s STEK\n", exim_tk
.name
[0] ? "rotating" : "creating");
870 if (RAND_bytes(exim_tk
.aes_key
, sizeof(exim_tk
.aes_key
)) <= 0) return;
871 if (RAND_bytes(exim_tk
.hmac_key
, sizeof(exim_tk
.hmac_key
)) <= 0) return;
872 if (RAND_bytes(exim_tk
.name
+1, sizeof(exim_tk
.name
)-1) <= 0) return;
874 exim_tk
.name
[0] = 'E';
875 exim_tk
.aes_cipher
= EVP_aes_256_cbc();
876 exim_tk
.hmac_hash
= EVP_sha256();
877 exim_tk
.expire
= t
+ ssl_session_timeout
;
878 exim_tk
.renew
= t
+ ssl_session_timeout
/2;
884 if (!exim_tk
.name
[0]) return NULL
;
889 tk_find(const uschar
* name
)
891 return memcmp(name
, exim_tk
.name
, sizeof(exim_tk
.name
)) == 0 ? &exim_tk
892 : memcmp(name
, exim_tk_old
.name
, sizeof(exim_tk_old
.name
)) == 0 ? &exim_tk_old
896 /* Callback for session tickets, on server */
898 ticket_key_callback(SSL
* ssl
, uschar key_name
[16],
899 uschar
* iv
, EVP_CIPHER_CTX
* ctx
, HMAC_CTX
* hctx
, int enc
)
901 tls_support
* tlsp
= server_static_cbinfo
->tlsp
;
906 DEBUG(D_tls
) debug_printf("ticket_key_callback: create new session\n");
907 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
909 if (RAND_bytes(iv
, EVP_MAX_IV_LENGTH
) <= 0)
910 return -1; /* insufficient random */
912 if (!(key
= tk_current())) /* current key doesn't exist or isn't valid */
913 return 0; /* key couldn't be created */
914 memcpy(key_name
, key
->name
, 16);
915 DEBUG(D_tls
) debug_printf("STEK expire " TIME_T_FMT
"\n", key
->expire
- time(NULL
));
917 /*XXX will want these dependent on the ssl session strength */
918 HMAC_Init_ex(hctx
, key
->hmac_key
, sizeof(key
->hmac_key
),
919 key
->hmac_hash
, NULL
);
920 EVP_EncryptInit_ex(ctx
, key
->aes_cipher
, NULL
, key
->aes_key
, iv
);
922 DEBUG(D_tls
) debug_printf("ticket created\n");
927 time_t now
= time(NULL
);
929 DEBUG(D_tls
) debug_printf("ticket_key_callback: retrieve session\n");
930 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
932 if (!(key
= tk_find(key_name
)) || key
->expire
< now
)
936 debug_printf("ticket not usable (%s)\n", key
? "expired" : "not found");
937 if (key
) debug_printf("STEK expire " TIME_T_FMT
"\n", key
->expire
- now
);
942 HMAC_Init_ex(hctx
, key
->hmac_key
, sizeof(key
->hmac_key
),
943 key
->hmac_hash
, NULL
);
944 EVP_DecryptInit_ex(ctx
, key
->aes_cipher
, NULL
, key
->aes_key
, iv
);
946 DEBUG(D_tls
) debug_printf("ticket usable, STEK expire " TIME_T_FMT
"\n", key
->expire
- now
);
948 /* The ticket lifetime and renewal are the same as the STEK lifetime and
949 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
950 be better. To do that we'd have to encode ticket lifetime in the name as
951 we don't yet see the restored session. Could check posthandshake for TLS1.3
952 and trigger a new ticket then, but cannot do that for TLS1.2 */
953 return key
->renew
< now
? 2 : 1;
960 /*************************************************
961 * Initialize for DH *
962 *************************************************/
964 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
967 sctx The current SSL CTX (inbound or outbound)
968 dhparam DH parameter file or fixed parameter identity string
969 host connected host, if client; NULL if server
970 errstr error string pointer
972 Returns: TRUE if OK (nothing to set up, or setup worked)
976 init_dh(SSL_CTX
*sctx
, uschar
*dhparam
, const host_item
*host
, uschar
** errstr
)
984 if (!expand_check(dhparam
, US
"tls_dhparam", &dhexpanded
, errstr
))
987 if (!dhexpanded
|| !*dhexpanded
)
988 bio
= BIO_new_mem_buf(CS
std_dh_prime_default(), -1);
989 else if (dhexpanded
[0] == '/')
991 if (!(bio
= BIO_new_file(CS dhexpanded
, "r")))
993 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded
),
994 host
, US
strerror(errno
), errstr
);
1000 if (Ustrcmp(dhexpanded
, "none") == 0)
1002 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
1006 if (!(pem
= std_dh_prime_named(dhexpanded
)))
1008 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded
),
1009 host
, US
strerror(errno
), errstr
);
1012 bio
= BIO_new_mem_buf(CS pem
, -1);
1015 if (!(dh
= PEM_read_bio_DHparams(bio
, NULL
, NULL
, NULL
)))
1018 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded
),
1019 host
, NULL
, errstr
);
1023 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
1024 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
1025 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
1026 * If someone wants to dance at the edge, then they can raise the limit or use
1027 * current libraries. */
1028 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
1029 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
1030 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
1031 dh_bitsize
= DH_bits(dh
);
1033 dh_bitsize
= 8 * DH_size(dh
);
1036 /* Even if it is larger, we silently return success rather than cause things
1037 * to fail out, so that a too-large DH will not knock out all TLS; it's a
1038 * debatable choice. */
1039 if (dh_bitsize
> tls_dh_max_bits
)
1042 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
1043 dh_bitsize
, tls_dh_max_bits
);
1047 SSL_CTX_set_tmp_dh(sctx
, dh
);
1049 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
1050 dhexpanded
? dhexpanded
: US
"default", dh_bitsize
);
1062 /*************************************************
1063 * Initialize for ECDH *
1064 *************************************************/
1066 /* Load parameters for ECDH encryption.
1068 For now, we stick to NIST P-256 because: it's simple and easy to configure;
1069 it avoids any patent issues that might bite redistributors; despite events in
1070 the news and concerns over curve choices, we're not cryptographers, we're not
1071 pretending to be, and this is "good enough" to be better than no support,
1072 protecting against most adversaries. Given another year or two, there might
1073 be sufficient clarity about a "right" way forward to let us make an informed
1074 decision, instead of a knee-jerk reaction.
1076 Longer-term, we should look at supporting both various named curves and
1077 external files generated with "openssl ecparam", much as we do for init_dh().
1078 We should also support "none" as a value, to explicitly avoid initialisation.
1083 sctx The current SSL CTX (inbound or outbound)
1084 host connected host, if client; NULL if server
1085 errstr error string pointer
1087 Returns: TRUE if OK (nothing to set up, or setup worked)
1091 init_ecdh(SSL_CTX
* sctx
, host_item
* host
, uschar
** errstr
)
1093 #ifdef OPENSSL_NO_ECDH
1102 if (host
) /* No ECDH setup for clients, only for servers */
1105 # ifndef EXIM_HAVE_ECDH
1107 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
1111 if (!expand_check(tls_eccurve
, US
"tls_eccurve", &exp_curve
, errstr
))
1113 if (!exp_curve
|| !*exp_curve
)
1116 /* "auto" needs to be handled carefully.
1117 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
1118 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
1119 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
1120 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
1121 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
1123 if (Ustrcmp(exp_curve
, "auto") == 0)
1125 #if OPENSSL_VERSION_NUMBER < 0x10002000L
1126 DEBUG(D_tls
) debug_printf(
1127 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
1128 exp_curve
= US
"prime256v1";
1130 # if defined SSL_CTRL_SET_ECDH_AUTO
1131 DEBUG(D_tls
) debug_printf(
1132 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
1133 SSL_CTX_set_ecdh_auto(sctx
, 1);
1136 DEBUG(D_tls
) debug_printf(
1137 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
1143 DEBUG(D_tls
) debug_printf("ECDH: curve '%s'\n", exp_curve
);
1144 if ( (nid
= OBJ_sn2nid (CCS exp_curve
)) == NID_undef
1145 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
1146 && (nid
= EC_curve_nist2nid(CCS exp_curve
)) == NID_undef
1150 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve
),
1151 host
, NULL
, errstr
);
1155 if (!(ecdh
= EC_KEY_new_by_curve_name(nid
)))
1157 tls_error(US
"Unable to create ec curve", host
, NULL
, errstr
);
1161 /* The "tmp" in the name here refers to setting a temporary key
1162 not to the stability of the interface. */
1164 if ((rv
= SSL_CTX_set_tmp_ecdh(sctx
, ecdh
) == 0))
1165 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve
), host
, NULL
, errstr
);
1167 DEBUG(D_tls
) debug_printf("ECDH: enabled '%s' curve\n", exp_curve
);
1172 # endif /*EXIM_HAVE_ECDH*/
1173 #endif /*OPENSSL_NO_ECDH*/
1179 #ifndef DISABLE_OCSP
1180 /*************************************************
1181 * Load OCSP information into state *
1182 *************************************************/
1183 /* Called to load the server OCSP response from the given file into memory, once
1184 caller has determined this is needed. Checks validity. Debugs a message
1187 ASSUMES: single response, for single cert.
1190 sctx the SSL_CTX* to update
1191 cbinfo various parts of session state
1192 expanded the filename putatively holding an OCSP response
1197 ocsp_load_response(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
, const uschar
*expanded
)
1200 OCSP_RESPONSE
* resp
;
1201 OCSP_BASICRESP
* basic_response
;
1202 OCSP_SINGLERESP
* single_response
;
1203 ASN1_GENERALIZEDTIME
* rev
, * thisupd
, * nextupd
;
1204 STACK_OF(X509
) * sk
;
1205 unsigned long verify_flags
;
1206 int status
, reason
, i
;
1208 cbinfo
->u_ocsp
.server
.file_expanded
= string_copy(expanded
);
1209 if (cbinfo
->u_ocsp
.server
.response
)
1211 OCSP_RESPONSE_free(cbinfo
->u_ocsp
.server
.response
);
1212 cbinfo
->u_ocsp
.server
.response
= NULL
;
1215 if (!(bio
= BIO_new_file(CS cbinfo
->u_ocsp
.server
.file_expanded
, "rb")))
1217 DEBUG(D_tls
) debug_printf("Failed to open OCSP response file \"%s\"\n",
1218 cbinfo
->u_ocsp
.server
.file_expanded
);
1222 resp
= d2i_OCSP_RESPONSE_bio(bio
, NULL
);
1226 DEBUG(D_tls
) debug_printf("Error reading OCSP response.\n");
1230 if ((status
= OCSP_response_status(resp
)) != OCSP_RESPONSE_STATUS_SUCCESSFUL
)
1232 DEBUG(D_tls
) debug_printf("OCSP response not valid: %s (%d)\n",
1233 OCSP_response_status_str(status
), status
);
1237 if (!(basic_response
= OCSP_response_get1_basic(resp
)))
1240 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1244 sk
= cbinfo
->verify_stack
;
1245 verify_flags
= OCSP_NOVERIFY
; /* check sigs, but not purpose */
1247 /* May need to expose ability to adjust those flags?
1248 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1249 OCSP_TRUSTOTHER OCSP_NOINTERN */
1251 /* This does a full verify on the OCSP proof before we load it for serving
1252 up; possibly overkill - just date-checks might be nice enough.
1254 OCSP_basic_verify takes a "store" arg, but does not
1255 use it for the chain verification, which is all we do
1256 when OCSP_NOVERIFY is set. The content from the wire
1257 "basic_response" and a cert-stack "sk" are all that is used.
1259 We have a stack, loaded in setup_certs() if tls_verify_certificates
1260 was a file (not a directory, or "system"). It is unfortunate we
1261 cannot used the connection context store, as that would neatly
1262 handle the "system" case too, but there seems to be no library
1263 function for getting a stack from a store.
1264 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1265 We do not free the stack since it could be needed a second time for
1268 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1269 be a public interface into the OpenSSL library (there's no manual entry) -
1270 But what with? We also use OCSP_basic_verify in the client stapling callback.
1271 And there we NEED it; we must verify that status... unless the
1272 library does it for us anyway? */
1274 if ((i
= OCSP_basic_verify(basic_response
, sk
, NULL
, verify_flags
)) < 0)
1278 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
1279 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring
);
1284 /* Here's the simplifying assumption: there's only one response, for the
1285 one certificate we use, and nothing for anything else in a chain. If this
1286 proves false, we need to extract a cert id from our issued cert
1287 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1288 right cert in the stack and then calls OCSP_single_get0_status()).
1290 I'm hoping to avoid reworking a bunch more of how we handle state here. */
1292 if (!(single_response
= OCSP_resp_get0(basic_response
, 0)))
1295 debug_printf("Unable to get first response from OCSP basic response.\n");
1299 status
= OCSP_single_get0_status(single_response
, &reason
, &rev
, &thisupd
, &nextupd
);
1300 if (status
!= V_OCSP_CERTSTATUS_GOOD
)
1302 DEBUG(D_tls
) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1303 OCSP_cert_status_str(status
), status
,
1304 OCSP_crl_reason_str(reason
), reason
);
1308 if (!OCSP_check_validity(thisupd
, nextupd
, EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1310 DEBUG(D_tls
) debug_printf("OCSP status invalid times.\n");
1315 /*XXX stack? (these tag points are for multiple leaf-cert support for ocsp */
1316 cbinfo
->u_ocsp
.server
.response
= resp
;
1320 if (f
.running_in_test_harness
)
1322 extern char ** environ
;
1323 if (environ
) for (uschar
** p
= USS environ
; *p
; p
++)
1324 if (Ustrncmp(*p
, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1326 DEBUG(D_tls
) debug_printf("Supplying known bad OCSP response\n");
1327 goto supply_response
;
1332 #endif /*!DISABLE_OCSP*/
1337 /* Create and install a selfsigned certificate, for use in server mode */
1340 tls_install_selfsign(SSL_CTX
* sctx
, uschar
** errstr
)
1348 where
= US
"allocating pkey";
1349 if (!(pkey
= EVP_PKEY_new()))
1352 where
= US
"allocating cert";
1353 if (!(x509
= X509_new()))
1356 where
= US
"generating pkey";
1357 if (!(rsa
= rsa_callback(NULL
, 0, 2048)))
1360 where
= US
"assigning pkey";
1361 if (!EVP_PKEY_assign_RSA(pkey
, rsa
))
1364 X509_set_version(x509
, 2); /* N+1 - version 3 */
1365 ASN1_INTEGER_set(X509_get_serialNumber(x509
), 1);
1366 X509_gmtime_adj(X509_get_notBefore(x509
), 0);
1367 X509_gmtime_adj(X509_get_notAfter(x509
), (long)60 * 60); /* 1 hour */
1368 X509_set_pubkey(x509
, pkey
);
1370 name
= X509_get_subject_name(x509
);
1371 X509_NAME_add_entry_by_txt(name
, "C",
1372 MBSTRING_ASC
, CUS
"UK", -1, -1, 0);
1373 X509_NAME_add_entry_by_txt(name
, "O",
1374 MBSTRING_ASC
, CUS
"Exim Developers", -1, -1, 0);
1375 X509_NAME_add_entry_by_txt(name
, "CN",
1376 MBSTRING_ASC
, CUS smtp_active_hostname
, -1, -1, 0);
1377 X509_set_issuer_name(x509
, name
);
1379 where
= US
"signing cert";
1380 if (!X509_sign(x509
, pkey
, EVP_md5()))
1383 where
= US
"installing selfsign cert";
1384 if (!SSL_CTX_use_certificate(sctx
, x509
))
1387 where
= US
"installing selfsign key";
1388 if (!SSL_CTX_use_PrivateKey(sctx
, pkey
))
1394 (void) tls_error(where
, NULL
, NULL
, errstr
);
1395 if (x509
) X509_free(x509
);
1396 if (pkey
) EVP_PKEY_free(pkey
);
1404 tls_add_certfile(SSL_CTX
* sctx
, tls_ext_ctx_cb
* cbinfo
, uschar
* file
,
1407 DEBUG(D_tls
) debug_printf("tls_certificate file %s\n", file
);
1408 if (!SSL_CTX_use_certificate_chain_file(sctx
, CS file
))
1409 return tls_error(string_sprintf(
1410 "SSL_CTX_use_certificate_chain_file file=%s", file
),
1411 cbinfo
->host
, NULL
, errstr
);
1416 tls_add_pkeyfile(SSL_CTX
* sctx
, tls_ext_ctx_cb
* cbinfo
, uschar
* file
,
1419 DEBUG(D_tls
) debug_printf("tls_privatekey file %s\n", file
);
1420 if (!SSL_CTX_use_PrivateKey_file(sctx
, CS file
, SSL_FILETYPE_PEM
))
1421 return tls_error(string_sprintf(
1422 "SSL_CTX_use_PrivateKey_file file=%s", file
), cbinfo
->host
, NULL
, errstr
);
1427 /*************************************************
1428 * Expand key and cert file specs *
1429 *************************************************/
1431 /* Called once during tls_init and possibly again during TLS setup, for a
1432 new context, if Server Name Indication was used and tls_sni was seen in
1433 the certificate string.
1436 sctx the SSL_CTX* to update
1437 cbinfo various parts of session state
1438 errstr error string pointer
1440 Returns: OK/DEFER/FAIL
1444 tls_expand_session_files(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
,
1449 if (!cbinfo
->certificate
)
1451 if (!cbinfo
->is_server
) /* client */
1454 if (tls_install_selfsign(sctx
, errstr
) != OK
)
1461 if (Ustrstr(cbinfo
->certificate
, US
"tls_sni") ||
1462 Ustrstr(cbinfo
->certificate
, US
"tls_in_sni") ||
1463 Ustrstr(cbinfo
->certificate
, US
"tls_out_sni")
1465 reexpand_tls_files_for_sni
= TRUE
;
1467 if (!expand_check(cbinfo
->certificate
, US
"tls_certificate", &expanded
, errstr
))
1471 if (cbinfo
->is_server
)
1473 const uschar
* file_list
= expanded
;
1477 while (file
= string_nextinlist(&file_list
, &sep
, NULL
, 0))
1478 if ((err
= tls_add_certfile(sctx
, cbinfo
, file
, errstr
)))
1481 else /* would there ever be a need for multiple client certs? */
1482 if ((err
= tls_add_certfile(sctx
, cbinfo
, expanded
, errstr
)))
1485 if ( cbinfo
->privatekey
1486 && !expand_check(cbinfo
->privatekey
, US
"tls_privatekey", &expanded
, errstr
))
1489 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1490 of the expansion is an empty string, ignore it also, and assume the private
1491 key is in the same file as the certificate. */
1493 if (expanded
&& *expanded
)
1494 if (cbinfo
->is_server
)
1496 const uschar
* file_list
= expanded
;
1500 while (file
= string_nextinlist(&file_list
, &sep
, NULL
, 0))
1501 if ((err
= tls_add_pkeyfile(sctx
, cbinfo
, file
, errstr
)))
1504 else /* would there ever be a need for multiple client certs? */
1505 if ((err
= tls_add_pkeyfile(sctx
, cbinfo
, expanded
, errstr
)))
1509 #ifndef DISABLE_OCSP
1510 if (cbinfo
->is_server
&& cbinfo
->u_ocsp
.server
.file
)
1513 if (!expand_check(cbinfo
->u_ocsp
.server
.file
, US
"tls_ocsp_file", &expanded
, errstr
))
1516 if (expanded
&& *expanded
)
1518 DEBUG(D_tls
) debug_printf("tls_ocsp_file %s\n", expanded
);
1519 if ( cbinfo
->u_ocsp
.server
.file_expanded
1520 && (Ustrcmp(expanded
, cbinfo
->u_ocsp
.server
.file_expanded
) == 0))
1522 DEBUG(D_tls
) debug_printf(" - value unchanged, using existing values\n");
1525 ocsp_load_response(sctx
, cbinfo
, expanded
);
1536 /*************************************************
1537 * Callback to handle SNI *
1538 *************************************************/
1540 /* Called when acting as server during the TLS session setup if a Server Name
1541 Indication extension was sent by the client.
1543 API documentation is OpenSSL s_server.c implementation.
1546 s SSL* of the current session
1547 ad unknown (part of OpenSSL API) (unused)
1548 arg Callback of "our" registered data
1550 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1552 XXX might need to change to using ClientHello callback,
1553 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
1556 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1558 tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
)
1560 const char *servername
= SSL_get_servername(s
, TLSEXT_NAMETYPE_host_name
);
1561 tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1563 int old_pool
= store_pool
;
1564 uschar
* dummy_errstr
;
1567 return SSL_TLSEXT_ERR_OK
;
1569 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", servername
,
1570 reexpand_tls_files_for_sni
? "" : " (unused for certificate selection)");
1572 /* Make the extension value available for expansion */
1573 store_pool
= POOL_PERM
;
1574 tls_in
.sni
= string_copy_taint(US servername
, TRUE
);
1575 store_pool
= old_pool
;
1577 if (!reexpand_tls_files_for_sni
)
1578 return SSL_TLSEXT_ERR_OK
;
1580 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1581 not confident that memcpy wouldn't break some internal reference counting.
1582 Especially since there's a references struct member, which would be off. */
1584 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1585 if (!(server_sni
= SSL_CTX_new(TLS_server_method())))
1587 if (!(server_sni
= SSL_CTX_new(SSLv23_server_method())))
1590 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
1591 DEBUG(D_tls
) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring
);
1595 /* Not sure how many of these are actually needed, since SSL object
1596 already exists. Might even need this selfsame callback, for reneg? */
1598 SSL_CTX_set_info_callback(server_sni
, SSL_CTX_get_info_callback(server_ctx
));
1599 SSL_CTX_set_mode(server_sni
, SSL_CTX_get_mode(server_ctx
));
1600 SSL_CTX_set_options(server_sni
, SSL_CTX_get_options(server_ctx
));
1601 SSL_CTX_set_timeout(server_sni
, SSL_CTX_get_timeout(server_ctx
));
1602 SSL_CTX_set_tlsext_servername_callback(server_sni
, tls_servername_cb
);
1603 SSL_CTX_set_tlsext_servername_arg(server_sni
, cbinfo
);
1605 if ( !init_dh(server_sni
, cbinfo
->dhparam
, NULL
, &dummy_errstr
)
1606 || !init_ecdh(server_sni
, NULL
, &dummy_errstr
)
1610 if ( cbinfo
->server_cipher_list
1611 && !SSL_CTX_set_cipher_list(server_sni
, CS cbinfo
->server_cipher_list
))
1614 #ifndef DISABLE_OCSP
1615 if (cbinfo
->u_ocsp
.server
.file
)
1617 SSL_CTX_set_tlsext_status_cb(server_sni
, tls_server_stapling_cb
);
1618 SSL_CTX_set_tlsext_status_arg(server_sni
, cbinfo
);
1622 if ((rc
= setup_certs(server_sni
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
,
1623 verify_callback_server
, &dummy_errstr
)) != OK
)
1626 /* do this after setup_certs, because this can require the certs for verifying
1627 OCSP information. */
1628 if ((rc
= tls_expand_session_files(server_sni
, cbinfo
, &dummy_errstr
)) != OK
)
1631 DEBUG(D_tls
) debug_printf("Switching SSL context.\n");
1632 SSL_set_SSL_CTX(s
, server_sni
);
1633 return SSL_TLSEXT_ERR_OK
;
1635 bad
: return SSL_TLSEXT_ERR_ALERT_FATAL
;
1637 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1642 #ifndef DISABLE_OCSP
1644 /*************************************************
1645 * Callback to handle OCSP Stapling *
1646 *************************************************/
1648 /* Called when acting as server during the TLS session setup if the client
1649 requests OCSP information with a Certificate Status Request.
1651 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1657 tls_server_stapling_cb(SSL
*s
, void *arg
)
1659 const tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1660 uschar
*response_der
; /*XXX blob */
1661 int response_der_len
;
1663 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1664 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1665 buggy in current OpenSSL; it returns the last cert loaded always rather than
1666 the one actually presented. So we can't support a stack of OCSP proofs at
1670 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1671 cbinfo
->u_ocsp
.server
.response
? "have" : "lack");
1673 tls_in
.ocsp
= OCSP_NOT_RESP
;
1674 if (!cbinfo
->u_ocsp
.server
.response
)
1675 return SSL_TLSEXT_ERR_NOACK
;
1677 response_der
= NULL
;
1678 response_der_len
= i2d_OCSP_RESPONSE(cbinfo
->u_ocsp
.server
.response
, /*XXX stack*/
1680 if (response_der_len
<= 0)
1681 return SSL_TLSEXT_ERR_NOACK
;
1683 SSL_set_tlsext_status_ocsp_resp(server_ssl
, response_der
, response_der_len
);
1684 tls_in
.ocsp
= OCSP_VFIED
;
1685 return SSL_TLSEXT_ERR_OK
;
1690 time_print(BIO
* bp
, const char * str
, ASN1_GENERALIZEDTIME
* time
)
1692 BIO_printf(bp
, "\t%s: ", str
);
1693 ASN1_GENERALIZEDTIME_print(bp
, time
);
1698 tls_client_stapling_cb(SSL
*s
, void *arg
)
1700 tls_ext_ctx_cb
* cbinfo
= arg
;
1701 const unsigned char * p
;
1703 OCSP_RESPONSE
* rsp
;
1704 OCSP_BASICRESP
* bs
;
1707 DEBUG(D_tls
) debug_printf("Received TLS status response (OCSP stapling):");
1708 len
= SSL_get_tlsext_status_ocsp_resp(s
, &p
);
1711 /* Expect this when we requested ocsp but got none */
1712 if (cbinfo
->u_ocsp
.client
.verify_required
&& LOGGING(tls_cipher
))
1713 log_write(0, LOG_MAIN
, "Received TLS status callback, null content");
1715 DEBUG(D_tls
) debug_printf(" null\n");
1716 return cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1719 if (!(rsp
= d2i_OCSP_RESPONSE(NULL
, &p
, len
)))
1721 tls_out
.ocsp
= OCSP_FAILED
; /*XXX should use tlsp-> to permit concurrent outbound */
1722 if (LOGGING(tls_cipher
))
1723 log_write(0, LOG_MAIN
, "Received TLS cert status response, parse error");
1725 DEBUG(D_tls
) debug_printf(" parse error\n");
1729 if (!(bs
= OCSP_response_get1_basic(rsp
)))
1731 tls_out
.ocsp
= OCSP_FAILED
;
1732 if (LOGGING(tls_cipher
))
1733 log_write(0, LOG_MAIN
, "Received TLS cert status response, error parsing response");
1735 DEBUG(D_tls
) debug_printf(" error parsing response\n");
1736 OCSP_RESPONSE_free(rsp
);
1740 /* We'd check the nonce here if we'd put one in the request. */
1741 /* However that would defeat cacheability on the server so we don't. */
1743 /* This section of code reworked from OpenSSL apps source;
1744 The OpenSSL Project retains copyright:
1745 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1750 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
1752 DEBUG(D_tls
) bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
1754 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1756 /* Use the chain that verified the server cert to verify the stapled info */
1757 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1759 if ((i
= OCSP_basic_verify(bs
, cbinfo
->verify_stack
,
1760 cbinfo
->u_ocsp
.client
.verify_store
, 0)) <= 0)
1762 tls_out
.ocsp
= OCSP_FAILED
;
1763 if (LOGGING(tls_cipher
)) log_write(0, LOG_MAIN
,
1764 "Received TLS cert status response, itself unverifiable: %s",
1765 ERR_reason_error_string(ERR_peek_error()));
1766 BIO_printf(bp
, "OCSP response verify failure\n");
1767 ERR_print_errors(bp
);
1768 OCSP_RESPONSE_print(bp
, rsp
, 0);
1772 BIO_printf(bp
, "OCSP response well-formed and signed OK\n");
1774 /*XXX So we have a good stapled OCSP status. How do we know
1775 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1776 OCSP_resp_find_status() which matches on a cert id, which presumably
1777 we should use. Making an id needs OCSP_cert_id_new(), which takes
1778 issuerName, issuerKey, serialNumber. Are they all in the cert?
1780 For now, carry on blindly accepting the resp. */
1783 OCSP_SINGLERESP
* single
;
1785 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1786 if (OCSP_resp_count(bs
) != 1)
1788 STACK_OF(OCSP_SINGLERESP
) * sresp
= bs
->tbsResponseData
->responses
;
1789 if (sk_OCSP_SINGLERESP_num(sresp
) != 1)
1792 tls_out
.ocsp
= OCSP_FAILED
;
1793 log_write(0, LOG_MAIN
, "OCSP stapling "
1794 "with multiple responses not handled");
1797 single
= OCSP_resp_get0(bs
, 0);
1798 status
= OCSP_single_get0_status(single
, &reason
, &rev
,
1799 &thisupd
, &nextupd
);
1802 DEBUG(D_tls
) time_print(bp
, "This OCSP Update", thisupd
);
1803 DEBUG(D_tls
) if(nextupd
) time_print(bp
, "Next OCSP Update", nextupd
);
1804 if (!OCSP_check_validity(thisupd
, nextupd
,
1805 EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1807 tls_out
.ocsp
= OCSP_FAILED
;
1808 DEBUG(D_tls
) ERR_print_errors(bp
);
1809 log_write(0, LOG_MAIN
, "Server OSCP dates invalid");
1813 DEBUG(D_tls
) BIO_printf(bp
, "Certificate status: %s\n",
1814 OCSP_cert_status_str(status
));
1817 case V_OCSP_CERTSTATUS_GOOD
:
1818 tls_out
.ocsp
= OCSP_VFIED
;
1821 case V_OCSP_CERTSTATUS_REVOKED
:
1822 tls_out
.ocsp
= OCSP_FAILED
;
1823 log_write(0, LOG_MAIN
, "Server certificate revoked%s%s",
1824 reason
!= -1 ? "; reason: " : "",
1825 reason
!= -1 ? OCSP_crl_reason_str(reason
) : "");
1826 DEBUG(D_tls
) time_print(bp
, "Revocation Time", rev
);
1829 tls_out
.ocsp
= OCSP_FAILED
;
1830 log_write(0, LOG_MAIN
,
1831 "Server certificate status unknown, in OCSP stapling");
1836 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1841 OCSP_RESPONSE_free(rsp
);
1844 #endif /*!DISABLE_OCSP*/
1847 /*************************************************
1848 * Initialize for TLS *
1849 *************************************************/
1851 /* Called from both server and client code, to do preliminary initialization
1852 of the library. We allocate and return a context structure.
1855 ctxp returned SSL context
1856 host connected host, if client; NULL if server
1857 dhparam DH parameter file
1858 certificate certificate file
1859 privatekey private key
1860 ocsp_file file of stapling info (server); flag for require ocsp (client)
1861 addr address if client; NULL if server (for some randomness)
1862 cbp place to put allocated callback context
1863 errstr error string pointer
1865 Returns: OK/DEFER/FAIL
1869 tls_init(SSL_CTX
**ctxp
, host_item
*host
, uschar
*dhparam
, uschar
*certificate
,
1871 #ifndef DISABLE_OCSP
1872 uschar
*ocsp_file
, /*XXX stack, in server*/
1874 address_item
*addr
, tls_ext_ctx_cb
** cbp
,
1881 tls_ext_ctx_cb
* cbinfo
;
1883 cbinfo
= store_malloc(sizeof(tls_ext_ctx_cb
));
1884 cbinfo
->tlsp
= tlsp
;
1885 cbinfo
->certificate
= certificate
;
1886 cbinfo
->privatekey
= privatekey
;
1887 cbinfo
->is_server
= host
==NULL
;
1888 #ifndef DISABLE_OCSP
1889 cbinfo
->verify_stack
= NULL
;
1892 cbinfo
->u_ocsp
.server
.file
= ocsp_file
;
1893 cbinfo
->u_ocsp
.server
.file_expanded
= NULL
;
1894 cbinfo
->u_ocsp
.server
.response
= NULL
;
1897 cbinfo
->u_ocsp
.client
.verify_store
= NULL
;
1899 cbinfo
->dhparam
= dhparam
;
1900 cbinfo
->server_cipher_list
= NULL
;
1901 cbinfo
->host
= host
;
1902 #ifndef DISABLE_EVENT
1903 cbinfo
->event_action
= NULL
;
1906 #ifdef EXIM_NEED_OPENSSL_INIT
1907 SSL_load_error_strings(); /* basic set up */
1908 OpenSSL_add_ssl_algorithms();
1911 #ifdef EXIM_HAVE_SHA256
1912 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1913 list of available digests. */
1914 EVP_add_digest(EVP_sha256());
1917 /* Create a context.
1918 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1919 negotiation in the different methods; as far as I can tell, the only
1920 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1921 when OpenSSL is built without SSLv2 support.
1922 By disabling with openssl_options, we can let admins re-enable with the
1925 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1926 if (!(ctx
= SSL_CTX_new(host
? TLS_client_method() : TLS_server_method())))
1928 if (!(ctx
= SSL_CTX_new(host
? SSLv23_client_method() : SSLv23_server_method())))
1930 return tls_error(US
"SSL_CTX_new", host
, NULL
, errstr
);
1932 /* It turns out that we need to seed the random number generator this early in
1933 order to get the full complement of ciphers to work. It took me roughly a day
1934 of work to discover this by experiment.
1936 On systems that have /dev/urandom, SSL may automatically seed itself from
1937 there. Otherwise, we have to make something up as best we can. Double check
1943 gettimeofday(&r
.tv
, NULL
);
1946 RAND_seed(US (&r
), sizeof(r
));
1947 RAND_seed(US big_buffer
, big_buffer_size
);
1948 if (addr
!= NULL
) RAND_seed(US addr
, sizeof(addr
));
1951 return tls_error(US
"RAND_status", host
,
1952 US
"unable to seed random number generator", errstr
);
1955 /* Set up the information callback, which outputs if debugging is at a suitable
1960 SSL_CTX_set_info_callback(ctx
, (void (*)())info_callback
);
1961 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1962 /* this needs a debug build of OpenSSL */
1963 SSL_CTX_set_msg_callback(ctx
, (void (*)())SSL_trace
);
1965 #ifdef OPENSSL_HAVE_KEYLOG_CB
1966 SSL_CTX_set_keylog_callback(ctx
, (void (*)())keylog_callback
);
1970 /* Automatically re-try reads/writes after renegotiation. */
1971 (void) SSL_CTX_set_mode(ctx
, SSL_MODE_AUTO_RETRY
);
1973 /* Apply administrator-supplied work-arounds.
1974 Historically we applied just one requested option,
1975 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1976 moved to an administrator-controlled list of options to specify and
1977 grandfathered in the first one as the default value for "openssl_options".
1979 No OpenSSL version number checks: the options we accept depend upon the
1980 availability of the option value macros from OpenSSL. */
1982 if (!tls_openssl_options_parse(openssl_options
, &init_options
))
1983 return tls_error(US
"openssl_options parsing failed", host
, NULL
, errstr
);
1985 #ifdef EXPERIMENTAL_TLS_RESUME
1986 tlsp
->resumption
= RESUME_SUPPORTED
;
1990 #ifdef EXPERIMENTAL_TLS_RESUME
1991 /* Should the server offer session resumption? */
1992 if (!host
&& verify_check_host(&tls_resumption_hosts
) == OK
)
1994 DEBUG(D_tls
) debug_printf("tls_resumption_hosts overrides openssl_options\n");
1995 init_options
&= ~SSL_OP_NO_TICKET
;
1996 tlsp
->resumption
|= RESUME_SERVER_TICKET
; /* server will give ticket on request */
1997 tlsp
->host_resumable
= TRUE
;
2001 DEBUG(D_tls
) debug_printf("setting SSL CTX options: %#lx\n", init_options
);
2002 if (!(SSL_CTX_set_options(ctx
, init_options
)))
2003 return tls_error(string_sprintf(
2004 "SSL_CTX_set_option(%#lx)", init_options
), host
, NULL
, errstr
);
2007 DEBUG(D_tls
) debug_printf("no SSL CTX options to set\n");
2009 /* We'd like to disable session cache unconditionally, but foolish Outlook
2010 Express clients then give up the first TLS connection and make a second one
2011 (which works). Only when there is an IMAP service on the same machine.
2012 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2013 now, until we work out a decent way of presenting control to the config. It
2014 will never be used because we use a new context every time. */
2016 (void) SSL_CTX_set_session_cache_mode(ctx
, SSL_SESS_CACHE_OFF
);
2019 /* Initialize with DH parameters if supplied */
2020 /* Initialize ECDH temp key parameter selection */
2022 if ( !init_dh(ctx
, dhparam
, host
, errstr
)
2023 || !init_ecdh(ctx
, host
, errstr
)
2027 /* Set up certificate and key (and perhaps OCSP info) */
2029 if ((rc
= tls_expand_session_files(ctx
, cbinfo
, errstr
)) != OK
)
2032 /* If we need to handle SNI or OCSP, do so */
2034 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2035 # ifndef DISABLE_OCSP
2036 if (!(cbinfo
->verify_stack
= sk_X509_new_null()))
2038 DEBUG(D_tls
) debug_printf("failed to create stack for stapling verify\n");
2043 if (!host
) /* server */
2045 # ifndef DISABLE_OCSP
2046 /* We check u_ocsp.server.file, not server.response, because we care about if
2047 the option exists, not what the current expansion might be, as SNI might
2048 change the certificate and OCSP file in use between now and the time the
2049 callback is invoked. */
2050 if (cbinfo
->u_ocsp
.server
.file
)
2052 SSL_CTX_set_tlsext_status_cb(ctx
, tls_server_stapling_cb
);
2053 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
2056 /* We always do this, so that $tls_sni is available even if not used in
2058 SSL_CTX_set_tlsext_servername_callback(ctx
, tls_servername_cb
);
2059 SSL_CTX_set_tlsext_servername_arg(ctx
, cbinfo
);
2061 # ifndef DISABLE_OCSP
2063 if(ocsp_file
) /* wanting stapling */
2065 if (!(cbinfo
->u_ocsp
.client
.verify_store
= X509_STORE_new()))
2067 DEBUG(D_tls
) debug_printf("failed to create store for stapling verify\n");
2070 SSL_CTX_set_tlsext_status_cb(ctx
, tls_client_stapling_cb
);
2071 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
2076 cbinfo
->verify_cert_hostnames
= NULL
;
2078 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2079 /* Set up the RSA callback */
2080 SSL_CTX_set_tmp_rsa_callback(ctx
, rsa_callback
);
2083 /* Finally, set the session cache timeout, and we are done.
2084 The period appears to be also used for (server-generated) session tickets */
2086 SSL_CTX_set_timeout(ctx
, ssl_session_timeout
);
2087 DEBUG(D_tls
) debug_printf("Initialized TLS\n");
2098 /*************************************************
2099 * Get name of cipher in use *
2100 *************************************************/
2103 Argument: pointer to an SSL structure for the connection
2104 pointer to number of bits for cipher
2105 Returns: pointer to allocated string in perm-pool
2109 construct_cipher_name(SSL
* ssl
, int * bits
)
2111 int pool
= store_pool
;
2112 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2113 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2114 the accessor functions use const in the prototype. */
2116 const uschar
* ver
= CUS
SSL_get_version(ssl
);
2117 const SSL_CIPHER
* c
= (const SSL_CIPHER
*) SSL_get_current_cipher(ssl
);
2120 SSL_CIPHER_get_bits(c
, bits
);
2122 store_pool
= POOL_PERM
;
2123 s
= string_sprintf("%s:%s:%u", ver
, SSL_CIPHER_get_name(c
), *bits
);
2125 DEBUG(D_tls
) debug_printf("Cipher: %s\n", s
);
2130 /* Get IETF-standard name for ciphersuite.
2131 Argument: pointer to an SSL structure for the connection
2132 Returns: pointer to string
2135 static const uschar
*
2136 cipher_stdname_ssl(SSL
* ssl
)
2138 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2139 return CUS
SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl
));
2141 ushort id
= 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl
));
2142 return cipher_stdname(id
>> 8, id
& 0xff);
2148 peer_cert(SSL
* ssl
, tls_support
* tlsp
, uschar
* peerdn
, unsigned siz
)
2150 /*XXX we might consider a list-of-certs variable for the cert chain.
2151 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2152 in list-handling functions, also consider the difference between the entire
2153 chain and the elements sent by the peer. */
2155 tlsp
->peerdn
= NULL
;
2157 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2158 if (!tlsp
->peercert
)
2159 tlsp
->peercert
= SSL_get_peer_certificate(ssl
);
2160 /* Beware anonymous ciphers which lead to server_cert being NULL */
2162 if (!X509_NAME_oneline(X509_get_subject_name(tlsp
->peercert
), CS peerdn
, siz
))
2163 { DEBUG(D_tls
) debug_printf("X509_NAME_oneline() error\n"); }
2166 int oldpool
= store_pool
;
2168 peerdn
[siz
-1] = '\0'; /* paranoia */
2169 store_pool
= POOL_PERM
;
2170 tlsp
->peerdn
= string_copy(peerdn
);
2171 store_pool
= oldpool
;
2173 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2174 but they don't get called on session-resumption. So use the official
2175 interface, which uses the resumed value. Unfortunately this claims verified
2176 when it actually failed but we're in try-verify mode, due to us wanting the
2177 knowlege that it failed so needing to have the callback and forcing a
2178 permissive return. If we don't force it, the TLS startup is failed.
2179 The extra bit of information is set in verify_override in the cb, stashed
2180 for resumption next to the TLS session, and used here. */
2182 if (!tlsp
->verify_override
)
2183 tlsp
->certificate_verified
= SSL_get_verify_result(ssl
) == X509_V_OK
;
2191 /*************************************************
2192 * Set up for verifying certificates *
2193 *************************************************/
2195 #ifndef DISABLE_OCSP
2196 /* Load certs from file, return TRUE on success */
2199 chain_from_pem_file(const uschar
* file
, STACK_OF(X509
) * verify_stack
)
2204 while (sk_X509_num(verify_stack
) > 0)
2205 X509_free(sk_X509_pop(verify_stack
));
2207 if (!(bp
= BIO_new_file(CS file
, "r"))) return FALSE
;
2208 while ((x
= PEM_read_bio_X509(bp
, NULL
, 0, NULL
)))
2209 sk_X509_push(verify_stack
, x
);
2217 /* Called by both client and server startup; on the server possibly
2218 repeated after a Server Name Indication.
2221 sctx SSL_CTX* to initialise
2222 certs certs file or NULL
2223 crl CRL file or NULL
2224 host NULL in a server; the remote host in a client
2225 optional TRUE if called from a server for a host in tls_try_verify_hosts;
2226 otherwise passed as FALSE
2227 cert_vfy_cb Callback function for certificate verification
2228 errstr error string pointer
2230 Returns: OK/DEFER/FAIL
2234 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
2235 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*), uschar
** errstr
)
2237 uschar
*expcerts
, *expcrl
;
2239 if (!expand_check(certs
, US
"tls_verify_certificates", &expcerts
, errstr
))
2241 DEBUG(D_tls
) debug_printf("tls_verify_certificates: %s\n", expcerts
);
2243 if (expcerts
&& *expcerts
)
2245 /* Tell the library to use its compiled-in location for the system default
2246 CA bundle. Then add the ones specified in the config, if any. */
2248 if (!SSL_CTX_set_default_verify_paths(sctx
))
2249 return tls_error(US
"SSL_CTX_set_default_verify_paths", host
, NULL
, errstr
);
2251 if (Ustrcmp(expcerts
, "system") != 0)
2253 struct stat statbuf
;
2255 if (Ustat(expcerts
, &statbuf
) < 0)
2257 log_write(0, LOG_MAIN
|LOG_PANIC
,
2258 "failed to stat %s for certificates", expcerts
);
2264 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
2265 { file
= NULL
; dir
= expcerts
; }
2268 file
= expcerts
; dir
= NULL
;
2269 #ifndef DISABLE_OCSP
2270 /* In the server if we will be offering an OCSP proof, load chain from
2271 file for verifying the OCSP proof at load time. */
2274 && statbuf
.st_size
> 0
2275 && server_static_cbinfo
->u_ocsp
.server
.file
2276 && !chain_from_pem_file(file
, server_static_cbinfo
->verify_stack
)
2279 log_write(0, LOG_MAIN
|LOG_PANIC
,
2280 "failed to load cert chain from %s", file
);
2286 /* If a certificate file is empty, the next function fails with an
2287 unhelpful error message. If we skip it, we get the correct behaviour (no
2288 certificates are recognized, but the error message is still misleading (it
2289 says no certificate was supplied). But this is better. */
2291 if ( (!file
|| statbuf
.st_size
> 0)
2292 && !SSL_CTX_load_verify_locations(sctx
, CS file
, CS dir
))
2293 return tls_error(US
"SSL_CTX_load_verify_locations", host
, NULL
, errstr
);
2295 /* Load the list of CAs for which we will accept certs, for sending
2296 to the client. This is only for the one-file tls_verify_certificates
2298 If a list isn't loaded into the server, but some verify locations are set,
2299 the server end appears to make a wildcard request for client certs.
2300 Meanwhile, the client library as default behaviour *ignores* the list
2301 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2302 Because of this, and that the dir variant is likely only used for
2303 the public-CA bundle (not for a private CA), not worth fixing. */
2307 STACK_OF(X509_NAME
) * names
= SSL_load_client_CA_file(CS file
);
2309 SSL_CTX_set_client_CA_list(sctx
, names
);
2310 DEBUG(D_tls
) debug_printf("Added %d certificate authorities.\n",
2311 sk_X509_NAME_num(names
));
2316 /* Handle a certificate revocation list. */
2318 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2320 /* This bit of code is now the version supplied by Lars Mainka. (I have
2321 merely reformatted it into the Exim code style.)
2323 "From here I changed the code to add support for multiple crl's
2324 in pem format in one file or to support hashed directory entries in
2325 pem format instead of a file. This method now uses the library function
2326 X509_STORE_load_locations to add the CRL location to the SSL context.
2327 OpenSSL will then handle the verify against CA certs and CRLs by
2328 itself in the verify callback." */
2330 if (!expand_check(crl
, US
"tls_crl", &expcrl
, errstr
)) return DEFER
;
2331 if (expcrl
&& *expcrl
)
2333 struct stat statbufcrl
;
2334 if (Ustat(expcrl
, &statbufcrl
) < 0)
2336 log_write(0, LOG_MAIN
|LOG_PANIC
,
2337 "failed to stat %s for certificates revocation lists", expcrl
);
2342 /* is it a file or directory? */
2344 X509_STORE
*cvstore
= SSL_CTX_get_cert_store(sctx
);
2345 if ((statbufcrl
.st_mode
& S_IFMT
) == S_IFDIR
)
2349 DEBUG(D_tls
) debug_printf("SSL CRL value is a directory %s\n", dir
);
2355 DEBUG(D_tls
) debug_printf("SSL CRL value is a file %s\n", file
);
2357 if (X509_STORE_load_locations(cvstore
, CS file
, CS dir
) == 0)
2358 return tls_error(US
"X509_STORE_load_locations", host
, NULL
, errstr
);
2360 /* setting the flags to check against the complete crl chain */
2362 X509_STORE_set_flags(cvstore
,
2363 X509_V_FLAG_CRL_CHECK
|X509_V_FLAG_CRL_CHECK_ALL
);
2367 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2369 /* If verification is optional, don't fail if no certificate */
2371 SSL_CTX_set_verify(sctx
,
2372 SSL_VERIFY_PEER
| (optional
? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT
),
2381 /*************************************************
2382 * Start a TLS session in a server *
2383 *************************************************/
2385 /* This is called when Exim is running as a server, after having received
2386 the STARTTLS command. It must respond to that command, and then negotiate
2390 require_ciphers allowed ciphers
2391 errstr pointer to error message
2393 Returns: OK on success
2394 DEFER for errors before the start of the negotiation
2395 FAIL for errors during the negotiation; the server can't
2400 tls_server_start(const uschar
* require_ciphers
, uschar
** errstr
)
2403 uschar
* expciphers
;
2404 tls_ext_ctx_cb
* cbinfo
;
2405 static uschar peerdn
[256];
2407 /* Check for previous activation */
2409 if (tls_in
.active
.sock
>= 0)
2411 tls_error(US
"STARTTLS received after TLS started", NULL
, US
"", errstr
);
2412 smtp_printf("554 Already in TLS\r\n", FALSE
);
2416 /* Initialize the SSL library. If it fails, it will already have logged
2419 rc
= tls_init(&server_ctx
, NULL
, tls_dhparam
, tls_certificate
, tls_privatekey
,
2420 #ifndef DISABLE_OCSP
2421 tls_ocsp_file
, /*XXX stack*/
2423 NULL
, &server_static_cbinfo
, &tls_in
, errstr
);
2424 if (rc
!= OK
) return rc
;
2425 cbinfo
= server_static_cbinfo
;
2427 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
, errstr
))
2430 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2431 were historically separated by underscores. So that I can use either form in my
2432 tests, and also for general convenience, we turn underscores into hyphens here.
2434 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2435 for TLS 1.3 . Since we do not call it at present we get the default list:
2436 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2441 for (uschar
* s
= expciphers
; *s
; s
++ ) if (*s
== '_') *s
= '-';
2442 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2443 if (!SSL_CTX_set_cipher_list(server_ctx
, CS expciphers
))
2444 return tls_error(US
"SSL_CTX_set_cipher_list", NULL
, NULL
, errstr
);
2445 cbinfo
->server_cipher_list
= expciphers
;
2448 /* If this is a host for which certificate verification is mandatory or
2449 optional, set up appropriately. */
2451 tls_in
.certificate_verified
= FALSE
;
2453 tls_in
.dane_verified
= FALSE
;
2455 server_verify_callback_called
= FALSE
;
2457 if (verify_check_host(&tls_verify_hosts
) == OK
)
2459 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
2460 FALSE
, verify_callback_server
, errstr
);
2461 if (rc
!= OK
) return rc
;
2462 server_verify_optional
= FALSE
;
2464 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
2466 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
2467 TRUE
, verify_callback_server
, errstr
);
2468 if (rc
!= OK
) return rc
;
2469 server_verify_optional
= TRUE
;
2472 #ifdef EXPERIMENTAL_TLS_RESUME
2473 SSL_CTX_set_tlsext_ticket_key_cb(server_ctx
, ticket_key_callback
);
2474 /* despite working, appears to always return failure, so ignoring */
2476 #ifdef OPENSSL_HAVE_NUM_TICKETS
2477 # ifdef EXPERIMENTAL_TLS_RESUME
2478 SSL_CTX_set_num_tickets(server_ctx
, tls_in
.host_resumable
? 1 : 0);
2480 SSL_CTX_set_num_tickets(server_ctx
, 0); /* send no TLS1.3 stateful-tickets */
2485 /* Prepare for new connection */
2487 if (!(server_ssl
= SSL_new(server_ctx
)))
2488 return tls_error(US
"SSL_new", NULL
, NULL
, errstr
);
2490 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2492 * With the SSL_clear(), we get strange interoperability bugs with
2493 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2494 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2496 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2497 * session shutdown. In this case, we have a brand new object and there's no
2498 * obvious reason to immediately clear it. I'm guessing that this was
2499 * originally added because of incomplete initialisation which the clear fixed,
2500 * in some historic release.
2503 /* Set context and tell client to go ahead, except in the case of TLS startup
2504 on connection, where outputting anything now upsets the clients and tends to
2505 make them disconnect. We need to have an explicit fflush() here, to force out
2506 the response. Other smtp_printf() calls do not need it, because in non-TLS
2507 mode, the fflush() happens when smtp_getc() is called. */
2509 SSL_set_session_id_context(server_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
2510 if (!tls_in
.on_connect
)
2512 smtp_printf("220 TLS go ahead\r\n", FALSE
);
2516 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2517 that the OpenSSL library doesn't. */
2519 SSL_set_wfd(server_ssl
, fileno(smtp_out
));
2520 SSL_set_rfd(server_ssl
, fileno(smtp_in
));
2521 SSL_set_accept_state(server_ssl
);
2523 DEBUG(D_tls
) debug_printf("Calling SSL_accept\n");
2525 sigalrm_seen
= FALSE
;
2526 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
2527 rc
= SSL_accept(server_ssl
);
2532 (void) tls_error(US
"SSL_accept", NULL
, sigalrm_seen
? US
"timed out" : NULL
, errstr
);
2536 DEBUG(D_tls
) debug_printf("SSL_accept was successful\n");
2537 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2538 anon-authentication ciphersuite negotiated. */
2540 #ifdef EXPERIMENTAL_TLS_RESUME
2541 if (SSL_session_reused(server_ssl
))
2543 tls_in
.resumption
|= RESUME_USED
;
2544 DEBUG(D_tls
) debug_printf("Session reused\n");
2548 /* TLS has been set up. Adjust the input functions to read via TLS,
2549 and initialize things. */
2551 peer_cert(server_ssl
, &tls_in
, peerdn
, sizeof(peerdn
));
2553 tls_in
.cipher
= construct_cipher_name(server_ssl
, &tls_in
.bits
);
2554 tls_in
.cipher_stdname
= cipher_stdname_ssl(server_ssl
);
2559 if (SSL_get_shared_ciphers(server_ssl
, CS buf
, sizeof(buf
)))
2560 debug_printf("Shared ciphers: %s\n", buf
);
2562 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
2564 BIO
* bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
2565 SSL_SESSION_print_keylog(bp
, SSL_get_session(server_ssl
));
2570 #ifdef EXIM_HAVE_SESSION_TICKET
2572 SSL_SESSION
* ss
= SSL_get_session(server_ssl
);
2573 if (SSL_SESSION_has_ticket(ss
)) /* 1.1.0 */
2574 debug_printf("The session has a ticket, life %lu seconds\n",
2575 SSL_SESSION_get_ticket_lifetime_hint(ss
));
2580 /* Record the certificate we presented */
2582 X509
* crt
= SSL_get_certificate(server_ssl
);
2583 tls_in
.ourcert
= crt
? X509_dup(crt
) : NULL
;
2586 /* Only used by the server-side tls (tls_in), including tls_getc.
2587 Client-side (tls_out) reads (seem to?) go via
2588 smtp_read_response()/ip_recv().
2589 Hence no need to duplicate for _in and _out.
2591 if (!ssl_xfer_buffer
) ssl_xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2592 ssl_xfer_buffer_lwm
= ssl_xfer_buffer_hwm
= 0;
2593 ssl_xfer_eof
= ssl_xfer_error
= FALSE
;
2595 receive_getc
= tls_getc
;
2596 receive_getbuf
= tls_getbuf
;
2597 receive_get_cache
= tls_get_cache
;
2598 receive_ungetc
= tls_ungetc
;
2599 receive_feof
= tls_feof
;
2600 receive_ferror
= tls_ferror
;
2601 receive_smtp_buffered
= tls_smtp_buffered
;
2603 tls_in
.active
.sock
= fileno(smtp_out
);
2604 tls_in
.active
.tls_ctx
= NULL
; /* not using explicit ctx for server-side */
2612 tls_client_basic_ctx_init(SSL_CTX
* ctx
,
2613 host_item
* host
, smtp_transport_options_block
* ob
, tls_ext_ctx_cb
* cbinfo
,
2617 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2618 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2619 the specified host patterns if one of them is defined */
2621 if ( ( !ob
->tls_verify_hosts
2622 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2624 || verify_check_given_host(CUSS
&ob
->tls_verify_hosts
, host
) == OK
2626 client_verify_optional
= FALSE
;
2627 else if (verify_check_given_host(CUSS
&ob
->tls_try_verify_hosts
, host
) == OK
)
2628 client_verify_optional
= TRUE
;
2632 if ((rc
= setup_certs(ctx
, ob
->tls_verify_certificates
,
2633 ob
->tls_crl
, host
, client_verify_optional
, verify_callback_client
,
2637 if (verify_check_given_host(CUSS
&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2639 cbinfo
->verify_cert_hostnames
=
2641 string_domain_utf8_to_alabel(host
->name
, NULL
);
2645 DEBUG(D_tls
) debug_printf("Cert hostname to check: \"%s\"\n",
2646 cbinfo
->verify_cert_hostnames
);
2654 dane_tlsa_load(SSL
* ssl
, host_item
* host
, dns_answer
* dnsa
, uschar
** errstr
)
2657 const char * hostnames
[2] = { CS host
->name
, NULL
};
2660 if (DANESSL_init(ssl
, NULL
, hostnames
) != 1)
2661 return tls_error(US
"hostnames load", host
, NULL
, errstr
);
2663 for (dns_record
* rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
); rr
;
2664 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2665 ) if (rr
->type
== T_TLSA
&& rr
->size
> 3)
2667 const uschar
* p
= rr
->data
;
2668 uint8_t usage
, selector
, mtype
;
2669 const char * mdname
;
2673 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2674 if (usage
!= 2 && usage
!= 3) continue;
2681 default: continue; /* Only match-types 0, 1, 2 are supported */
2682 case 0: mdname
= NULL
; break;
2683 case 1: mdname
= "sha256"; break;
2684 case 2: mdname
= "sha512"; break;
2688 switch (DANESSL_add_tlsa(ssl
, usage
, selector
, mdname
, p
, rr
->size
- 3))
2691 return tls_error(US
"tlsa load", host
, NULL
, errstr
);
2692 case 0: /* action not taken */
2696 tls_out
.tlsa_usage
|= 1<<usage
;
2702 log_write(0, LOG_MAIN
, "DANE error: No usable TLSA records");
2705 #endif /*SUPPORT_DANE*/
2709 #ifdef EXPERIMENTAL_TLS_RESUME
2710 /* On the client, get any stashed session for the given IP from hints db
2711 and apply it to the ssl-connection for attempted resumption. */
2714 tls_retrieve_session(tls_support
* tlsp
, SSL
* ssl
, const uschar
* key
)
2716 tlsp
->resumption
|= RESUME_SUPPORTED
;
2717 if (tlsp
->host_resumable
)
2719 dbdata_tls_session
* dt
;
2721 open_db dbblock
, * dbm_file
;
2723 tlsp
->resumption
|= RESUME_CLIENT_REQUESTED
;
2724 DEBUG(D_tls
) debug_printf("checking for resumable session for %s\n", key
);
2725 if ((dbm_file
= dbfn_open(US
"tls", O_RDONLY
, &dbblock
, FALSE
, FALSE
)))
2727 /* key for the db is the IP */
2728 if ((dt
= dbfn_read_with_length(dbm_file
, key
, &len
)))
2730 SSL_SESSION
* ss
= NULL
;
2731 const uschar
* sess_asn1
= dt
->session
;
2733 len
-= sizeof(dbdata_tls_session
);
2734 if (!(d2i_SSL_SESSION(&ss
, &sess_asn1
, (long)len
)))
2738 ERR_error_string_n(ERR_get_error(),
2739 ssl_errstring
, sizeof(ssl_errstring
));
2740 debug_printf("decoding session: %s\n", ssl_errstring
);
2743 #ifdef EXIM_HAVE_SESSION_TICKET
2744 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss
) + dt
->time_stamp
2747 DEBUG(D_tls
) debug_printf("session expired\n");
2748 dbfn_delete(dbm_file
, key
);
2751 else if (!SSL_set_session(ssl
, ss
))
2755 ERR_error_string_n(ERR_get_error(),
2756 ssl_errstring
, sizeof(ssl_errstring
));
2757 debug_printf("applying session to ssl: %s\n", ssl_errstring
);
2762 DEBUG(D_tls
) debug_printf("good session\n");
2763 tlsp
->resumption
|= RESUME_CLIENT_SUGGESTED
;
2764 tlsp
->verify_override
= dt
->verify_override
;
2765 tlsp
->ocsp
= dt
->ocsp
;
2769 DEBUG(D_tls
) debug_printf("no session record\n");
2770 dbfn_close(dbm_file
);
2776 /* On the client, save the session for later resumption */
2779 tls_save_session_cb(SSL
* ssl
, SSL_SESSION
* ss
)
2781 tls_ext_ctx_cb
* cbinfo
= SSL_get_ex_data(ssl
, tls_exdata_idx
);
2784 DEBUG(D_tls
) debug_printf("tls_save_session_cb\n");
2786 if (!cbinfo
|| !(tlsp
= cbinfo
->tlsp
)->host_resumable
) return 0;
2788 # ifdef OPENSSL_HAVE_NUM_TICKETS
2789 if (SSL_SESSION_is_resumable(ss
)) /* 1.1.1 */
2792 int len
= i2d_SSL_SESSION(ss
, NULL
);
2793 int dlen
= sizeof(dbdata_tls_session
) + len
;
2794 dbdata_tls_session
* dt
= store_get(dlen
, TRUE
);
2795 uschar
* s
= dt
->session
;
2796 open_db dbblock
, * dbm_file
;
2798 DEBUG(D_tls
) debug_printf("session is resumable\n");
2799 tlsp
->resumption
|= RESUME_SERVER_TICKET
; /* server gave us a ticket */
2801 dt
->verify_override
= tlsp
->verify_override
;
2802 dt
->ocsp
= tlsp
->ocsp
;
2803 (void) i2d_SSL_SESSION(ss
, &s
); /* s gets bumped to end */
2805 if ((dbm_file
= dbfn_open(US
"tls", O_RDWR
, &dbblock
, FALSE
, FALSE
)))
2807 const uschar
* key
= cbinfo
->host
->address
;
2808 dbfn_delete(dbm_file
, key
);
2809 dbfn_write(dbm_file
, key
, dt
, dlen
);
2810 dbfn_close(dbm_file
);
2811 DEBUG(D_tls
) debug_printf("wrote session (len %u) to db\n",
2820 tls_client_ctx_resume_prehandshake(
2821 exim_openssl_client_tls_ctx
* exim_client_ctx
, tls_support
* tlsp
,
2822 smtp_transport_options_block
* ob
, host_item
* host
)
2824 /* Should the client request a session resumption ticket? */
2825 if (verify_check_given_host(CUSS
&ob
->tls_resumption_hosts
, host
) == OK
)
2827 tlsp
->host_resumable
= TRUE
;
2829 SSL_CTX_set_session_cache_mode(exim_client_ctx
->ctx
,
2830 SSL_SESS_CACHE_CLIENT
2831 | SSL_SESS_CACHE_NO_INTERNAL
| SSL_SESS_CACHE_NO_AUTO_CLEAR
);
2832 SSL_CTX_sess_set_new_cb(exim_client_ctx
->ctx
, tls_save_session_cb
);
2837 tls_client_ssl_resume_prehandshake(SSL
* ssl
, tls_support
* tlsp
,
2838 host_item
* host
, uschar
** errstr
)
2840 if (tlsp
->host_resumable
)
2843 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
2844 SSL_clear_options(ssl
, SSL_OP_NO_TICKET
);
2846 tls_exdata_idx
= SSL_get_ex_new_index(0, 0, 0, 0, 0);
2847 if (!SSL_set_ex_data(ssl
, tls_exdata_idx
, client_static_cbinfo
))
2849 tls_error(US
"set ex_data", host
, NULL
, errstr
);
2852 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx
, client_static_cbinfo
);
2855 tlsp
->resumption
= RESUME_SUPPORTED
;
2856 /* Pick up a previous session, saved on an old ticket */
2857 tls_retrieve_session(tlsp
, ssl
, host
->address
);
2862 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx
* exim_client_ctx
,
2865 if (SSL_session_reused(exim_client_ctx
->ssl
))
2867 DEBUG(D_tls
) debug_printf("The session was reused\n");
2868 tlsp
->resumption
|= RESUME_USED
;
2871 #endif /* EXPERIMENTAL_TLS_RESUME */
2874 /*************************************************
2875 * Start a TLS session in a client *
2876 *************************************************/
2878 /* Called from the smtp transport after STARTTLS has been accepted.
2881 cctx connection context
2882 conn_args connection details
2883 cookie datum for randomness; can be NULL
2884 tlsp record details of TLS channel configuration here; must be non-NULL
2885 errstr error string pointer
2887 Returns: TRUE for success with TLS session context set in connection context,
2892 tls_client_start(client_conn_ctx
* cctx
, smtp_connect_args
* conn_args
,
2893 void * cookie
, tls_support
* tlsp
, uschar
** errstr
)
2895 host_item
* host
= conn_args
->host
; /* for msgs and option-tests */
2896 transport_instance
* tb
= conn_args
->tblock
; /* always smtp or NULL */
2897 smtp_transport_options_block
* ob
= tb
2898 ? (smtp_transport_options_block
*)tb
->options_block
2899 : &smtp_transport_option_defaults
;
2900 exim_openssl_client_tls_ctx
* exim_client_ctx
;
2901 uschar
* expciphers
;
2903 static uschar peerdn
[256];
2905 #ifndef DISABLE_OCSP
2906 BOOL request_ocsp
= FALSE
;
2907 BOOL require_ocsp
= FALSE
;
2911 store_pool
= POOL_PERM
;
2912 exim_client_ctx
= store_get(sizeof(exim_openssl_client_tls_ctx
), FALSE
);
2913 exim_client_ctx
->corked
= NULL
;
2917 tlsp
->tlsa_usage
= 0;
2920 #ifndef DISABLE_OCSP
2922 # ifdef SUPPORT_DANE
2923 if ( conn_args
->dane
2924 && ob
->hosts_request_ocsp
[0] == '*'
2925 && ob
->hosts_request_ocsp
[1] == '\0'
2928 /* Unchanged from default. Use a safer one under DANE */
2929 request_ocsp
= TRUE
;
2930 ob
->hosts_request_ocsp
= US
"${if or { {= {0}{$tls_out_tlsa_usage}} "
2931 " {= {4}{$tls_out_tlsa_usage}} } "
2937 verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
))
2938 request_ocsp
= TRUE
;
2940 # ifdef SUPPORT_DANE
2944 verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
2948 rc
= tls_init(&exim_client_ctx
->ctx
, host
, NULL
,
2949 ob
->tls_certificate
, ob
->tls_privatekey
,
2950 #ifndef DISABLE_OCSP
2951 (void *)(long)request_ocsp
,
2953 cookie
, &client_static_cbinfo
, tlsp
, errstr
);
2954 if (rc
!= OK
) return FALSE
;
2956 tlsp
->certificate_verified
= FALSE
;
2957 client_verify_callback_called
= FALSE
;
2961 if (conn_args
->dane
)
2963 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2964 other failures should be treated as problems. */
2965 if (ob
->dane_require_tls_ciphers
&&
2966 !expand_check(ob
->dane_require_tls_ciphers
, US
"dane_require_tls_ciphers",
2967 &expciphers
, errstr
))
2969 if (expciphers
&& *expciphers
== '\0')
2974 !expand_check(ob
->tls_require_ciphers
, US
"tls_require_ciphers",
2975 &expciphers
, errstr
))
2978 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2979 are separated by underscores. So that I can use either form in my tests, and
2980 also for general convenience, we turn underscores into hyphens here. */
2984 uschar
*s
= expciphers
;
2985 while (*s
) { if (*s
== '_') *s
= '-'; s
++; }
2986 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2987 if (!SSL_CTX_set_cipher_list(exim_client_ctx
->ctx
, CS expciphers
))
2989 tls_error(US
"SSL_CTX_set_cipher_list", host
, NULL
, errstr
);
2995 if (conn_args
->dane
)
2997 SSL_CTX_set_verify(exim_client_ctx
->ctx
,
2998 SSL_VERIFY_PEER
| SSL_VERIFY_FAIL_IF_NO_PEER_CERT
,
2999 verify_callback_client_dane
);
3001 if (!DANESSL_library_init())
3003 tls_error(US
"library init", host
, NULL
, errstr
);
3006 if (DANESSL_CTX_init(exim_client_ctx
->ctx
) <= 0)
3008 tls_error(US
"context init", host
, NULL
, errstr
);
3016 if (tls_client_basic_ctx_init(exim_client_ctx
->ctx
, host
, ob
,
3017 client_static_cbinfo
, errstr
) != OK
)
3020 #ifdef EXPERIMENTAL_TLS_RESUME
3021 tls_client_ctx_resume_prehandshake(exim_client_ctx
, tlsp
, ob
, host
);
3025 if (!(exim_client_ctx
->ssl
= SSL_new(exim_client_ctx
->ctx
)))
3027 tls_error(US
"SSL_new", host
, NULL
, errstr
);
3030 SSL_set_session_id_context(exim_client_ctx
->ssl
, sid_ctx
, Ustrlen(sid_ctx
));
3032 SSL_set_fd(exim_client_ctx
->ssl
, cctx
->sock
);
3033 SSL_set_connect_state(exim_client_ctx
->ssl
);
3037 if (!expand_check(ob
->tls_sni
, US
"tls_sni", &tlsp
->sni
, errstr
))
3041 DEBUG(D_tls
) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3043 else if (!Ustrlen(tlsp
->sni
))
3047 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3048 DEBUG(D_tls
) debug_printf("Setting TLS SNI \"%s\"\n", tlsp
->sni
);
3049 SSL_set_tlsext_host_name(exim_client_ctx
->ssl
, tlsp
->sni
);
3051 log_write(0, LOG_MAIN
, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3058 if (conn_args
->dane
)
3059 if (dane_tlsa_load(exim_client_ctx
->ssl
, host
, &conn_args
->tlsa_dnsa
, errstr
) != OK
)
3063 #ifndef DISABLE_OCSP
3064 /* Request certificate status at connection-time. If the server
3065 does OCSP stapling we will get the callback (set in tls_init()) */
3066 # ifdef SUPPORT_DANE
3070 if ( ((s
= ob
->hosts_require_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
3071 || ((s
= ob
->hosts_request_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
3073 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3074 this means we avoid the OCSP request, we wasted the setup
3075 cost in tls_init(). */
3076 require_ocsp
= verify_check_given_host(CUSS
&ob
->hosts_require_ocsp
, host
) == OK
;
3077 request_ocsp
= require_ocsp
3078 || verify_check_given_host(CUSS
&ob
->hosts_request_ocsp
, host
) == OK
;
3085 SSL_set_tlsext_status_type(exim_client_ctx
->ssl
, TLSEXT_STATUSTYPE_ocsp
);
3086 client_static_cbinfo
->u_ocsp
.client
.verify_required
= require_ocsp
;
3087 tlsp
->ocsp
= OCSP_NOT_RESP
;
3091 #ifdef EXPERIMENTAL_TLS_RESUME
3092 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx
->ssl
, tlsp
, host
,
3097 #ifndef DISABLE_EVENT
3098 client_static_cbinfo
->event_action
= tb
? tb
->event_action
: NULL
;
3101 /* There doesn't seem to be a built-in timeout on connection. */
3103 DEBUG(D_tls
) debug_printf("Calling SSL_connect\n");
3104 sigalrm_seen
= FALSE
;
3105 ALARM(ob
->command_timeout
);
3106 rc
= SSL_connect(exim_client_ctx
->ssl
);
3110 if (conn_args
->dane
)
3111 DANESSL_cleanup(exim_client_ctx
->ssl
);
3116 tls_error(US
"SSL_connect", host
, sigalrm_seen
? US
"timed out" : NULL
, errstr
);
3122 debug_printf("SSL_connect succeeded\n");
3123 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3125 BIO
* bp
= BIO_new_fp(debug_file
, BIO_NOCLOSE
);
3126 SSL_SESSION_print_keylog(bp
, SSL_get_session(exim_client_ctx
->ssl
));
3132 #ifdef EXPERIMENTAL_TLS_RESUME
3133 tls_client_resume_posthandshake(exim_client_ctx
, tlsp
);
3136 peer_cert(exim_client_ctx
->ssl
, tlsp
, peerdn
, sizeof(peerdn
));
3138 tlsp
->cipher
= construct_cipher_name(exim_client_ctx
->ssl
, &tlsp
->bits
);
3139 tlsp
->cipher_stdname
= cipher_stdname_ssl(exim_client_ctx
->ssl
);
3141 /* Record the certificate we presented */
3143 X509
* crt
= SSL_get_certificate(exim_client_ctx
->ssl
);
3144 tlsp
->ourcert
= crt
? X509_dup(crt
) : NULL
;
3147 tlsp
->active
.sock
= cctx
->sock
;
3148 tlsp
->active
.tls_ctx
= exim_client_ctx
;
3149 cctx
->tls_ctx
= exim_client_ctx
;
3158 tls_refill(unsigned lim
)
3163 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl
,
3164 ssl_xfer_buffer
, ssl_xfer_buffer_size
);
3166 if (smtp_receive_timeout
> 0) ALARM(smtp_receive_timeout
);
3167 inbytes
= SSL_read(server_ssl
, CS ssl_xfer_buffer
,
3168 MIN(ssl_xfer_buffer_size
, lim
));
3169 error
= SSL_get_error(server_ssl
, inbytes
);
3170 if (smtp_receive_timeout
> 0) ALARM_CLR(0);
3172 if (had_command_timeout
) /* set by signal handler */
3173 smtp_command_timeout_exit(); /* does not return */
3174 if (had_command_sigterm
)
3175 smtp_command_sigterm_exit();
3176 if (had_data_timeout
)
3177 smtp_data_timeout_exit();
3178 if (had_data_sigint
)
3179 smtp_data_sigint_exit();
3181 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3182 closed down, not that the socket itself has been closed down. Revert to
3183 non-SSL handling. */
3187 case SSL_ERROR_NONE
:
3190 case SSL_ERROR_ZERO_RETURN
:
3191 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3193 if (SSL_get_shutdown(server_ssl
) == SSL_RECEIVED_SHUTDOWN
)
3194 SSL_shutdown(server_ssl
);
3196 tls_close(NULL
, TLS_NO_SHUTDOWN
);
3199 /* Handle genuine errors */
3201 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3202 log_write(0, LOG_MAIN
, "TLS error (SSL_read): %s", ssl_errstring
);
3203 ssl_xfer_error
= TRUE
;
3207 DEBUG(D_tls
) debug_printf("Got SSL error %d\n", error
);
3208 DEBUG(D_tls
) if (error
== SSL_ERROR_SYSCALL
)
3209 debug_printf(" - syscall %s\n", strerror(errno
));
3210 ssl_xfer_error
= TRUE
;
3214 #ifndef DISABLE_DKIM
3215 dkim_exim_verify_feed(ssl_xfer_buffer
, inbytes
);
3217 ssl_xfer_buffer_hwm
= inbytes
;
3218 ssl_xfer_buffer_lwm
= 0;
3223 /*************************************************
3224 * TLS version of getc *
3225 *************************************************/
3227 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3228 it refills the buffer via the SSL reading function.
3230 Arguments: lim Maximum amount to read/buffer
3231 Returns: the next character or EOF
3233 Only used by the server-side TLS.
3237 tls_getc(unsigned lim
)
3239 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
3240 if (!tls_refill(lim
))
3241 return ssl_xfer_error
? EOF
: smtp_getc(lim
);
3243 /* Something in the buffer; return next uschar */
3245 return ssl_xfer_buffer
[ssl_xfer_buffer_lwm
++];
3249 tls_getbuf(unsigned * len
)
3254 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
3255 if (!tls_refill(*len
))
3257 if (!ssl_xfer_error
) return smtp_getbuf(len
);
3262 if ((size
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
) > *len
)
3264 buf
= &ssl_xfer_buffer
[ssl_xfer_buffer_lwm
];
3265 ssl_xfer_buffer_lwm
+= size
;
3274 #ifndef DISABLE_DKIM
3275 int n
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
;
3277 dkim_exim_verify_feed(ssl_xfer_buffer
+ssl_xfer_buffer_lwm
, n
);
3283 tls_could_read(void)
3285 return ssl_xfer_buffer_lwm
< ssl_xfer_buffer_hwm
|| SSL_pending(server_ssl
) > 0;
3289 /*************************************************
3290 * Read bytes from TLS channel *
3291 *************************************************/
3295 ct_ctx client context pointer, or NULL for the one global server context
3299 Returns: the number of bytes read
3300 -1 after a failed read, including EOF
3302 Only used by the client-side TLS.
3306 tls_read(void * ct_ctx
, uschar
*buff
, size_t len
)
3308 SSL
* ssl
= ct_ctx
? ((exim_openssl_client_tls_ctx
*)ct_ctx
)->ssl
: server_ssl
;
3312 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl
,
3313 buff
, (unsigned int)len
);
3315 inbytes
= SSL_read(ssl
, CS buff
, len
);
3316 error
= SSL_get_error(ssl
, inbytes
);
3318 if (error
== SSL_ERROR_ZERO_RETURN
)
3320 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3323 else if (error
!= SSL_ERROR_NONE
)
3333 /*************************************************
3334 * Write bytes down TLS channel *
3335 *************************************************/
3339 ct_ctx client context pointer, or NULL for the one global server context
3342 more further data expected soon
3344 Returns: the number of bytes after a successful write,
3345 -1 after a failed write
3347 Used by both server-side and client-side TLS.
3351 tls_write(void * ct_ctx
, const uschar
*buff
, size_t len
, BOOL more
)
3354 int outbytes
, error
;
3356 ? ((exim_openssl_client_tls_ctx
*)ct_ctx
)->ssl
: server_ssl
;
3357 static gstring
* server_corked
= NULL
;
3358 gstring
** corkedp
= ct_ctx
3359 ? &((exim_openssl_client_tls_ctx
*)ct_ctx
)->corked
: &server_corked
;
3360 gstring
* corked
= *corkedp
;
3362 DEBUG(D_tls
) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__
,
3363 buff
, (unsigned long)len
, more
? ", more" : "");
3365 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
3366 "more" is notified. This hack is only ok if small amounts are involved AND only
3367 one stream does it, in one context (i.e. no store reset). Currently it is used
3368 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
3369 We support callouts done by the server process by using a separate client
3370 context for the stashed information. */
3371 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
3372 a store reset there, so use POOL_PERM. */
3373 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
3375 if ((more
|| corked
))
3377 #ifdef SUPPORT_PIPE_CONNECT
3378 int save_pool
= store_pool
;
3379 store_pool
= POOL_PERM
;
3382 corked
= string_catn(corked
, buff
, len
);
3384 #ifdef SUPPORT_PIPE_CONNECT
3385 store_pool
= save_pool
;
3393 buff
= CUS corked
->s
;
3398 for (int left
= len
; left
> 0;)
3400 DEBUG(D_tls
) debug_printf("SSL_write(%p, %p, %d)\n", ssl
, buff
, left
);
3401 outbytes
= SSL_write(ssl
, CS buff
, left
);
3402 error
= SSL_get_error(ssl
, outbytes
);
3403 DEBUG(D_tls
) debug_printf("outbytes=%d error=%d\n", outbytes
, error
);
3407 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3408 log_write(0, LOG_MAIN
, "TLS error (SSL_write): %s", ssl_errstring
);
3411 case SSL_ERROR_NONE
:
3416 case SSL_ERROR_ZERO_RETURN
:
3417 log_write(0, LOG_MAIN
, "SSL channel closed on write");
3420 case SSL_ERROR_SYSCALL
:
3421 log_write(0, LOG_MAIN
, "SSL_write: (from %s) syscall: %s",
3422 sender_fullhost
? sender_fullhost
: US
"<unknown>",
3427 log_write(0, LOG_MAIN
, "SSL_write error %d", error
);
3436 /*************************************************
3437 * Close down a TLS session *
3438 *************************************************/
3440 /* This is also called from within a delivery subprocess forked from the
3441 daemon, to shut down the TLS library, without actually doing a shutdown (which
3442 would tamper with the SSL session in the parent process).
3445 ct_ctx client TLS context pointer, or NULL for the one global server context
3446 shutdown 1 if TLS close-alert is to be sent,
3447 2 if also response to be waited for
3451 Used by both server-side and client-side TLS.
3455 tls_close(void * ct_ctx
, int shutdown
)
3457 exim_openssl_client_tls_ctx
* o_ctx
= ct_ctx
;
3458 SSL_CTX
**ctxp
= o_ctx
? &o_ctx
->ctx
: &server_ctx
;
3459 SSL
**sslp
= o_ctx
? &o_ctx
->ssl
: &server_ssl
;
3460 int *fdp
= o_ctx
? &tls_out
.active
.sock
: &tls_in
.active
.sock
;
3462 if (*fdp
< 0) return; /* TLS was not active */
3467 DEBUG(D_tls
) debug_printf("tls_close(): shutting down TLS%s\n",
3468 shutdown
> 1 ? " (with response-wait)" : "");
3470 if ( (rc
= SSL_shutdown(*sslp
)) == 0 /* send "close notify" alert */
3474 rc
= SSL_shutdown(*sslp
); /* wait for response */
3478 if (rc
< 0) DEBUG(D_tls
)
3480 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3481 debug_printf("SSL_shutdown: %s\n", ssl_errstring
);
3485 if (!o_ctx
) /* server side */
3487 #ifndef DISABLE_OCSP
3488 sk_X509_pop_free(server_static_cbinfo
->verify_stack
, X509_free
);
3489 server_static_cbinfo
->verify_stack
= NULL
;
3492 receive_getc
= smtp_getc
;
3493 receive_getbuf
= smtp_getbuf
;
3494 receive_get_cache
= smtp_get_cache
;
3495 receive_ungetc
= smtp_ungetc
;
3496 receive_feof
= smtp_feof
;
3497 receive_ferror
= smtp_ferror
;
3498 receive_smtp_buffered
= smtp_buffered
;
3499 tls_in
.active
.tls_ctx
= NULL
;
3501 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3504 SSL_CTX_free(*ctxp
);
3514 /*************************************************
3515 * Let tls_require_ciphers be checked at startup *
3516 *************************************************/
3518 /* The tls_require_ciphers option, if set, must be something which the
3521 Returns: NULL on success, or error message
3525 tls_validate_require_cipher(void)
3528 uschar
*s
, *expciphers
, *err
;
3530 /* this duplicates from tls_init(), we need a better "init just global
3531 state, for no specific purpose" singleton function of our own */
3533 #ifdef EXIM_NEED_OPENSSL_INIT
3534 SSL_load_error_strings();
3535 OpenSSL_add_ssl_algorithms();
3537 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
3538 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
3539 list of available digests. */
3540 EVP_add_digest(EVP_sha256());
3543 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
3546 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
,
3548 return US
"failed to expand tls_require_ciphers";
3550 if (!(expciphers
&& *expciphers
))
3553 /* normalisation ripped from above */
3555 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
3559 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3560 if (!(ctx
= SSL_CTX_new(TLS_server_method())))
3562 if (!(ctx
= SSL_CTX_new(SSLv23_server_method())))
3565 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3566 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring
);
3570 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
3572 if (!SSL_CTX_set_cipher_list(ctx
, CS expciphers
))
3574 ERR_error_string_n(ERR_get_error(), ssl_errstring
, sizeof(ssl_errstring
));
3575 err
= string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3576 expciphers
, ssl_errstring
);
3587 /*************************************************
3588 * Report the library versions. *
3589 *************************************************/
3591 /* There have historically been some issues with binary compatibility in
3592 OpenSSL libraries; if Exim (like many other applications) is built against
3593 one version of OpenSSL but the run-time linker picks up another version,
3594 it can result in serious failures, including crashing with a SIGSEGV. So
3595 report the version found by the compiler and the run-time version.
3597 Note: some OS vendors backport security fixes without changing the version
3598 number/string, and the version date remains unchanged. The _build_ date
3599 will change, so we can more usefully assist with version diagnosis by also
3600 reporting the build date.
3602 Arguments: a FILE* to print the results to
3607 tls_version_report(FILE *f
)
3609 fprintf(f
, "Library version: OpenSSL: Compile: %s\n"
3612 OPENSSL_VERSION_TEXT
,
3613 SSLeay_version(SSLEAY_VERSION
),
3614 SSLeay_version(SSLEAY_BUILT_ON
));
3615 /* third line is 38 characters for the %s and the line is 73 chars long;
3616 the OpenSSL output includes a "built on: " prefix already. */
3622 /*************************************************
3623 * Random number generation *
3624 *************************************************/
3626 /* Pseudo-random number generation. The result is not expected to be
3627 cryptographically strong but not so weak that someone will shoot themselves
3628 in the foot using it as a nonce in input in some email header scheme or
3629 whatever weirdness they'll twist this into. The result should handle fork()
3630 and avoid repeating sequences. OpenSSL handles that for us.
3634 Returns a random number in range [0, max-1]
3638 vaguely_random_number(int max
)
3642 static pid_t pidlast
= 0;
3644 uschar smallbuf
[sizeof(r
)];
3650 if (pidnow
!= pidlast
)
3652 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3653 is unique for each thread", this doesn't apparently apply across processes,
3654 so our own warning from vaguely_random_number_fallback() applies here too.
3655 Fix per PostgreSQL. */
3661 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3665 gettimeofday(&r
.tv
, NULL
);
3668 RAND_seed(US (&r
), sizeof(r
));
3670 /* We're after pseudo-random, not random; if we still don't have enough data
3671 in the internal PRNG then our options are limited. We could sleep and hope
3672 for entropy to come along (prayer technique) but if the system is so depleted
3673 in the first place then something is likely to just keep taking it. Instead,
3674 we'll just take whatever little bit of pseudo-random we can still manage to
3677 needed_len
= sizeof(r
);
3678 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3679 asked for a number less than 10. */
3680 for (r
= max
, i
= 0; r
; ++i
)
3686 #ifdef EXIM_HAVE_RAND_PSEUDO
3687 /* We do not care if crypto-strong */
3688 i
= RAND_pseudo_bytes(smallbuf
, needed_len
);
3690 i
= RAND_bytes(smallbuf
, needed_len
);
3696 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3697 return vaguely_random_number_fallback(max
);
3701 for (uschar
* p
= smallbuf
; needed_len
; --needed_len
, ++p
)
3704 /* We don't particularly care about weighted results; if someone wants
3705 smooth distribution and cares enough then they should submit a patch then. */
3712 /*************************************************
3713 * OpenSSL option parse *
3714 *************************************************/
3716 /* Parse one option for tls_openssl_options_parse below
3719 name one option name
3720 value place to store a value for it
3721 Returns success or failure in parsing
3727 tls_openssl_one_option_parse(uschar
*name
, long *value
)
3730 int last
= exim_openssl_options_size
;
3731 while (last
> first
)
3733 int middle
= (first
+ last
)/2;
3734 int c
= Ustrcmp(name
, exim_openssl_options
[middle
].name
);
3737 *value
= exim_openssl_options
[middle
].value
;
3751 /*************************************************
3752 * OpenSSL option parsing logic *
3753 *************************************************/
3755 /* OpenSSL has a number of compatibility options which an administrator might
3756 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3757 we look like log_selector.
3760 option_spec the administrator-supplied string of options
3761 results ptr to long storage for the options bitmap
3762 Returns success or failure
3766 tls_openssl_options_parse(uschar
*option_spec
, long *results
)
3771 BOOL adding
, item_parsed
;
3773 /* Server: send no (<= TLS1.2) session tickets */
3774 result
= SSL_OP_NO_TICKET
;
3776 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3777 * from default because it increases BEAST susceptibility. */
3778 #ifdef SSL_OP_NO_SSLv2
3779 result
|= SSL_OP_NO_SSLv2
;
3781 #ifdef SSL_OP_NO_SSLv3
3782 result
|= SSL_OP_NO_SSLv3
;
3784 #ifdef SSL_OP_SINGLE_DH_USE
3785 result
|= SSL_OP_SINGLE_DH_USE
;
3794 for (uschar
* s
= option_spec
; *s
; /**/)
3796 while (isspace(*s
)) ++s
;
3799 if (*s
!= '+' && *s
!= '-')
3801 DEBUG(D_tls
) debug_printf("malformed openssl option setting: "
3802 "+ or - expected but found \"%s\"\n", s
);
3805 adding
= *s
++ == '+';
3806 for (end
= s
; (*end
!= '\0') && !isspace(*end
); ++end
) /**/ ;
3809 item_parsed
= tls_openssl_one_option_parse(s
, &item
);
3813 DEBUG(D_tls
) debug_printf("openssl option setting unrecognised: \"%s\"\n", s
);
3816 DEBUG(D_tls
) debug_printf("openssl option, %s %8lx: %lx (%s)\n",
3817 adding
? "adding to " : "removing from", result
, item
, s
);
3829 #endif /*!MACRO_PREDEF*/
3832 /* End of tls-openssl.c */